Optical thin films and display devices using them

Abstract

This invention provides an optical thin film that enables display devices to achieve low reflectivity, high brightness, and thinness, as well as a display device using the same, and a composition for forming an ultraviolet absorbing layer used in the manufacture of the optical thin film. An optical thin film is characterized by comprising: a transparent substrate; a coloring layer deposited on one side of the transparent substrate and containing a pigment; and a functional layer deposited on the coloring layer; wherein the pigment contains a first color material with a maximum absorption wavelength in the range of 470-530 nm and a second color material with a maximum absorption wavelength in the range of 560-620 nm, the functional layer comprises an ultraviolet absorbing layer with an ultraviolet shading rate of 85% or more, and its surface has a pencil hardness of H or higher under a 500g load.

Description

Technical Field

[0001] This invention relates to an optical thin film, a display device using the optical thin film, and a composition for forming an ultraviolet absorbing layer for manufacturing the optical thin film. Prior Technology

[0002] Display devices, whether indoors or outdoors, are mostly used in environments with external light incident on them. External light incident on a display device is reflected off its surface, and this reflected image mixes with the displayed image, thus degrading display quality. Therefore, display devices must be equipped with anti-reflective capabilities, and to improve display quality, high-performance anti-reflective functions are required.

[0003] Generally, anti-reflective properties can be achieved by forming a low-refractive-index layer on the surface of a display device. Furthermore, to further enhance the anti-reflective performance, it is known to provide a high-refractive-index layer, or both a medium-refractive-index layer and a high-refractive-index layer, and form a low-refractive-index layer on the outermost surface.

[0004] Furthermore, there is a problem: external light incident on the display device is reflected by components inside the display device (e.g., electrodes, phosphors, color filters), and the reflected light is emitted again from the display surface, thus reducing the display quality. To address this problem, it is known that a method can be used to reduce the incident light into the display device and the reflected light inside by placing a circular polarizer on the display surface side (e.g., see Patent Document 1).

[0005] Furthermore, display devices generally require high color purity. Color purity refers to the breadth of colors a display device can display, also known as the color reproduction range. Therefore, high color purity means a wide color reproduction range and good color reproduction. Regarding the improvement of color reproduction, it is known that: color separation is performed using color filters for the white light source of the display panel, or color filters are used to correct the monochromatic light source, thereby narrowing the half-width at half-maximum (HWHM). [Previous Technical Documents] [Patent Literature]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2013-251376 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] In display devices that use circular polarizers to provide anti-reflective properties, the light emitted from the display panel is also absorbed by the polarizer. If absorption by thin films and other materials outside the polarizer is also considered, the transmittance of light emitted from the display panel is less than 50%, resulting in a significant reduction in brightness. The luminous intensity of the display panel must be increased to compensate for the reduced brightness, but this may lead to a decrease in the lifespan of the light-emitting elements. Furthermore, the thickness of the circular polarizer itself makes it difficult to achieve a thinner form factor.

[0009] Furthermore, improving the color reproduction of display devices requires thickening of color filters and increasing the concentration of color materials, which leads to problems such as deterioration of pixel shape and viewing angle characteristics, resulting in a decrease in display quality.

[0010] Therefore, the object of the present invention is to provide an optical thin film, a display device using the optical thin film, and a composition for forming an ultraviolet absorption layer for manufacturing the optical thin film, wherein the optical thin film can achieve low reflectivity, high brightness, thin film, and improved color reproduction of the display device. [Methods used to solve problems]

[0011] The optical thin film of the present invention is characterized by comprising: a transparent substrate; a coloring layer deposited on one side of the transparent substrate and containing a pigment; and a functional layer deposited on the coloring layer. The pigment comprises: a first colorant having a maximum absorption wavelength in the range of 470-530 nm and a half-width at half-maximum (WHM) of the absorption spectrum of 15-45 nm; and a second colorant having a maximum absorption wavelength in the range of 560-620 nm and a WHM of the absorption spectrum of 15-55 nm; the functional layer comprises an ultraviolet absorbing layer having an ultraviolet shielding rate of 85% or higher according to JIS L 1925, and its surface having a pencil hardness of H or higher under a 500g load.

[0012] Furthermore, the display device of the present invention includes the aforementioned optical thin film.

[0013] Furthermore, the composition for forming the ultraviolet absorption layer of the present invention is an ultraviolet absorption layer for forming an optical thin film, the optical thin film comprising: a transparent substrate; a coloring layer deposited on one side of the transparent substrate and containing a pigment; and a functional layer deposited on the coloring layer; the pigment comprising: a first color material having a maximum absorption wavelength in the range of 470-530 nm and a half-width at half-maximum (WHM) of the absorption spectrum of 15-45 nm; and a second color material having a maximum absorption wavelength in the range of 560-620 nm and a WHM of the absorption spectrum of 15-55 nm; the functional layer comprising an ultraviolet absorption layer having an ultraviolet shielding rate of 85% or more according to JIS L 1925, and the surface having a pencil hardness of H or more under a 500g load. The composition for forming the ultraviolet absorption layer is characterized by containing at least an active energy line curing resin, a photopolymerizable compound, an ultraviolet absorber, and a solvent. The absorption wavelength range of the photopolymerization initiator in the ultraviolet region is different from that of the ultraviolet absorber in the ultraviolet region. The absorption wavelength range of the ultraviolet absorber in the ultraviolet region is in the range of 290~370nm. [Effects of the Invention]

[0014] According to the present invention, an optical thin film, a display device using the optical thin film, and a composition for forming an ultraviolet absorption layer for manufacturing the optical thin film are provided. The optical thin film can achieve low reflectivity, high brightness, thinness, and improved color reproduction of the display device. Simple Explanation of the Diagram

[0015] Figure 1 is a cross-sectional view showing the schematic configuration of the display device in the first embodiment. Figure 2 is a cross-sectional view showing the schematic configuration of the display device in the second embodiment. Figure 3 is a cross-sectional view showing the schematic configuration of the display device in the third embodiment. Figure 4 is a cross-sectional view showing the schematic configuration of the display device in the fourth embodiment. Figure 5 is a cross-sectional view showing the schematic configuration of the display device in the fifth embodiment. Figure 6 shows the spectrum of a light source used to evaluate its transmission characteristics. Figure 7 shows the spectrum of a light source used to evaluate color reproduction. Implementation

[0016] [The form in which the invention is carried out]

[0017] Figures 1 to 5 are cross-sectional views showing the schematic configuration of the display device in embodiments 1 to 5, respectively. The upper side in Figures 1 to 5 corresponds to the viewing side when viewing the displayed image of the display device.

[0018] The details are described below. The optical films 11-15 shown in Figures 1-5 include a coloring layer 21 containing a pigment that absorbs light in a specific wavelength range. The coloring layer 21 functions to absorb a portion of the external light incident on the optical films 11-15 and a portion of the external light reflected from the display panel 10, thereby reducing the reflected light. However, if the pigment contained in the coloring layer 21 has low lightfastness and is photo-oxidized by ultraviolet light contained in the external light, the light absorption may decrease. Therefore, in this invention, an ultraviolet absorption layer that absorbs ultraviolet light is provided in a functional layer closer to the observation side than the coloring layer 21, thereby suppressing the deterioration (fading) of the coloring layer 21 caused by incident ultraviolet light.

[0019] The display device 1 shown in Figure 1 includes a display panel 10 and an optical film 11 disposed on the display surface side of the display panel 10. The display panel 10 is a display panel with a light source, especially in the case of self-emissive panels such as organic EL panels or micro light-emitting diode (Micro LED) panels, which may have metal electrodes or reflective components. The optical film 11 includes: a transparent substrate 20; a coloring layer 21 deposited on one side of the transparent substrate 20; a hard coating layer 22; and a low refractive index layer 23, which is a functional layer deposited on the coloring layer 21. In the optical film 11, the low refractive index layer 23 forms the outermost surface of the viewing side of the display device 1, and the other side of the transparent substrate 20 is superimposed on the display panel 10 with the display surface side facing the display panel 10. The refractive index of the low refractive index layer 23 is lower than the refractive index of the hard coating layer 22, and the hard coating layer 22 and the low refractive index layer 23 together form an anti-reflective layer. The hard coating 22 and the low-refractive-index layer 23 reduce the reflection of external light by interfering with and canceling out the reflected light reflected from the interlayer within the optical thin film 11. In the example of Figure 1, the hard coating 22 contains an ultraviolet absorber, thereby functioning as an ultraviolet absorbing layer. However, the low-refractive-index layer 23 can also be used as an ultraviolet absorbing layer instead of the hard coating 22, or both the hard coating 22 and the low-refractive-index layer 23 can be used as ultraviolet absorbing layers.

[0020] The display device 2 shown in Figure 2 includes a display panel 10 and an optical film 12 disposed on the display surface side of the display panel 10. The optical film 12 includes: a transparent substrate 20; a coloring layer 21 deposited on one side of the transparent substrate 20; and an anti-glare layer 24, which is a functional layer deposited on the coloring layer 21. In the optical film 12, the anti-glare layer 24 forms the outermost surface of the viewing side of the display device 2, and the other side of the transparent substrate 20 is overlapped onto the display panel 10 facing the display surface side. The anti-glare layer 24 is an optical functional layer used to control the reflection of external light. It scatters external light through fine irregularities formed on its surface, thereby reducing the amount of external light entering the device. In the example of Figure 2, the anti-glare layer 24 contains an ultraviolet absorber, thereby functioning as an ultraviolet absorption layer.

[0021] The display device 3 shown in Figure 3 includes a display panel 10 and an optical film 13 disposed on the display surface side of the display panel 10. The optical film 13 includes: a transparent substrate 20; a coloring layer 21 deposited on one side of the transparent substrate 20; a hard coating layer 22; and an anti-glare layer 25, which is a functional layer deposited on the coloring layer 21. In the optical film 13, the anti-glare layer 25 is the outermost surface of the viewing side of the display device 2, and the other side of the transparent substrate 20 is overlapped on the display panel 10 facing the display surface side of the display panel 10. The anti-glare layer 25 is an optical functional layer used to control the reflection of external light. It scatters external light by forming fine unevenness on the surface, thereby reducing the amount of external light entering. Furthermore, the refractive index of the anti-glare layer 25 is lower than that of the hard coating layer 22, and the hard coating layer 22 and the anti-glare layer 25 together constitute an anti-reflection layer. In the example of Figure 3, the hard coating layer 22 contains an ultraviolet absorber, thereby functioning as an ultraviolet absorption layer. However, the anti-glare layer 25 can also be used as an ultraviolet absorption layer instead of the hard coating layer 22, or the hard coating layer 22 can also have the anti-glare layer 25 as an ultraviolet absorption layer.

[0022] The display device 4 shown in Figure 4 includes a display panel 10 and an optical film 14 disposed on the display surface side of the display panel 10. The optical film 14 includes: a transparent substrate 20; a coloring layer 21 deposited on one side of the transparent substrate 20; and an anti-glare layer 24 and a low refractive index layer 23, which are functional layers deposited on the coloring layer 21. In the optical film 14, the low refractive index layer 23 forms the outermost surface of the viewing side of the display device 2, and the other side of the transparent substrate 20 is superimposed on the display panel 10 facing the display surface side of the display panel 10. The anti-glare layer 24 is an optical functional layer used to control the reflection of external light. It scatters external light by forming fine irregularities on the surface, thereby reducing the amount of external light entering. Furthermore, the refractive index of the low refractive index layer 23 is lower than that of the anti-glare layer 24, and the anti-glare layer 24 and the low refractive index layer 23 together constitute an anti-reflection layer. In the example of Figure 4, the anti-glare layer 24 contains an ultraviolet absorber, thereby functioning as an ultraviolet absorption layer. However, the low refractive index layer 23 can also be used as an ultraviolet absorption layer to replace the anti-glare layer 24, or the anti-glare layer 24 and the low refractive index layer 23 can be used as ultraviolet absorption layers.

[0023] Preferably, the optical thin film of the present invention further comprises an oxygen barrier layer having oxygen barrier properties within a functional layer located closer to the visual recognition side than the coloring layer 21. As an example, the configuration formed by further adding an oxygen barrier layer to the optical thin film 11 shown in FIG. 1 is shown in FIG. 5.

[0024] The display device 5 shown in Figure 5 includes a display panel 10 and an optical film 15 disposed on the display surface side of the display panel 10. The optical film 15 includes: a transparent substrate 20; a coloring layer 21 deposited on one side of the transparent substrate 20; and an oxygen barrier layer 26, a hard coating layer 22, and a low refractive index layer 23, which serve as functional layers deposited on the coloring layer 21. In the optical film 15, the low refractive index layer 23 forms the outermost surface of the viewing side of the display device 1, and the other side of the transparent substrate 20 is overlapped on the display panel 10 facing the display surface side of the display panel 10. Similar to the first embodiment, the hard coating layer 22 and the low refractive index layer 23 constitute an anti-reflective layer that controls the reflection of external light. In the example of Figure 5, the hard coating layer 22 contains an ultraviolet absorber, thereby functioning as an ultraviolet absorbing layer. However, the low refractive index layer 23 can also be used as an ultraviolet absorbing layer instead of the hard coating layer 22, or the hard coating layer 22 can also have the low refractive index layer 23 as an ultraviolet absorbing layer.

[0025] Optical films 11-15 have a pencil hardness of H or higher under a 500g load. Films with a pencil hardness less than H are not suitable for use as reflective control films applied to the surface of display devices.

[0026] Furthermore, optical films 11-15 can be adhered to the display surface of the display panel 10 through an adhesive layer not shown in the figure.

[0027] The following describes the details of each layer of the optical thin films 11 to 15.

[0028] <Transparent substrate> The transparent substrate 20 is a thin film used as the substrate for optical thin films 11-15, and is formed from a material with excellent visible light transmittance. Materials forming the transparent substrate 20 can include polyethylene, polyolefins such as polypropylene, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyacrylates such as polymethyl methacrylate, polyamides such as nylon 6 and nylon 66, polyimide, polyarylate, polycarbonate, triacetyl cellulose, polyacrylate, polyvinyl alcohol, polyvinyl chloride, cyclic olefin copolymers, resins containing norbornene, polyether ether, polyurethane, and inorganic glass. Thin films made of polyethylene terephthalate are particularly suitable. The thickness of the transparent substrate 20 is not particularly limited, but is preferably 10-100 μm.

[0029] <shading layer> The coloring layer 21 is a layer used to reduce light penetrating the optical films 11-15 and reflected light that is reflected and then emitted again after being reflected by the metal electrode components or reflective components of the display panel 10. It contains pigments for selectively absorbing wavelengths of visible light. In this embodiment, the coloring layer 21 contains a first color material and a second color material as pigments. The maximum absorption wavelength of the first color material is in the range of 470-530 nm, and the full width at half maximum (FWHM) of the absorption spectrum is 15-45 nm. The maximum absorption wavelength of the second color material is in the range of 560-620 nm, and the FWHM of the absorption spectrum is 15-55 nm. By using the first and second color materials containing the above-mentioned absorption characteristics as the first and second color materials contained in the coloring layer 21, visible light in the wavelength range with relatively low luminous intensity emitted by the display panel 10 can be absorbed by the coloring layer 21.

[0030] Although an anti-reflective layer or an anti-glare layer is provided as a functional layer on the surface of the optical films 11-15 attached to the display devices 1-5, a portion of the external light incident on the display devices 1-5 penetrates the optical functional layer and reaches the display panel 10, where it is reflected by the metal electrode components or reflective components of the display panel 10. The light reflected from inside the display devices 1-3 can impair the contrast and visual recognizability of the displayed image on the display panel 10. Therefore, previously, circular polarizers were used to reduce reflected light on the surface of the display panel 10. In this embodiment, the optical films 11-15 absorb a portion of the incident light that penetrates the optical functional layer using a pigment-containing coloring layer 21, instead of using a circular polarizer to reduce reflected light. A portion of the remaining incident light not absorbed by the coloring layer 21 is reflected by the display panel 10, but the coloring layer 21 further absorbs a portion of the reflected light. This significantly reduces the internal reflectivity of external light. The absorption wavelength range of the pigment contained in the color layer 21 does not overlap with the maximum wavelength of the light emitted from the display panel 10, thus suppressing the reduction in the intensity of the light emitted from the display panel 10.

[0031] The thickness of the coloring layer 21 is not particularly limited, but is preferably 0.5 to 10 μm. If the thickness of the coloring layer 21 is less than 0.5 μm, the pigment concentration in the coloring layer 21 may be insufficient, resulting in insufficient light absorption. If the pigment concentration is increased to ensure light absorption when the thickness of the coloring layer 21 is less than 0.5 μm, the appearance will be abnormal, which is undesirable. On the other hand, if the thickness of the coloring layer 21 exceeds 10 μm, it will be detrimental to the thinning of the optical films 11 to 15, which is also undesirable.

[0032] As the pigment contained in the coloring layer 21, dyes, pigments, nano-metals, etc., can be used, but it is preferable to use a color material containing the following compounds: selected from one or more compounds and their metal complexes containing any one of the following structures: porphyrin, anthocyanin, phthalocyanine, azo, anthocyanin, squaric acid cyanine, coumarin, polyene, tetra-diporphyrin, pyrromethene, and indigo. Metal complexes containing porphyrin, pyrromethene, phthalocyanine, or squaric acid cyanine structures are particularly preferred.

[0033] Furthermore, in addition to the two color materials mentioned above, the color layer 21 may also contain a third color material with a maximum absorption wavelength in the range of 650~900nm. However, the third color material is a pigment whose maximum absorption wavelength is different from the maximum emission wavelength of the display panel 10. By containing the third color material in the color layer 21, the reflection of external light can be further reduced.

[0034] Hard coating The hard coating 22 is a layer used to impart hardness to optical films 11, 13, and 15. It can be formed by coating a hard coating forming composition containing at least an active energy line curing resin, a photopolymerization initiator, and a solvent, and then curing it. The thickness of the hard coating 22 is not particularly limited, but is preferably 2 to 10 μm. If the thickness of the hard coating 22 is less than 2 μm, the hardness of the hard coating 22 may be insufficient. If the thickness of the hard coating 22 exceeds 10 μm, it is not conducive to the thinning of optical films 11, 13, and 15, and is therefore undesirable. However, the film thickness of the hard coating 22 can be appropriately set according to the required surface hardness and overall thickness of the optical film. Furthermore, for the purpose of adjusting the refractive index or imparting hardness, the hard coating 22 may also contain metal oxide microparticles. By incorporating metal oxide microparticles into the hard coating 22 to increase its refractive index, it can form an anti-reflective layer together with the low refractive index layer 23 described below.

[0035] Active energy line curable resins are resins that polymerize and harden when exposed to active energy lines such as ultraviolet light or electron beams. For example, monofunctional, difunctional, or trifunctional (meth)acrylate monomers can be used. Furthermore, in this specification, "(meth)acrylate" is a collective term for both acrylate and methacrylate, and "(meth)acryl" is a collective term for both acrylonitrile and methacryl.

[0036] Examples of monofunctional (meth)acrylate compounds include: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tributyl (meth)acrylate, glycidyl (meth)acrylate, acrylonitrile, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isocamphene (meth)acrylate, etc. Isodecyl acrylate, dodecyl acrylate, tridecyl acrylate, hexadecyl acrylate, octadecyl acrylate, benzyl acrylate, 2-ethoxyethyl acrylate, 3-methoxybutyl acrylate, ethyl carbitol acrylate, meth acrylate, ethylene oxide modified meth acrylate, phenoxy acrylate, ethylene oxide modified phenoxy (meth) acrylate, propylene oxide modified phenoxy (meth) acrylate Acrylic esters, nonylphenol (meth) acrylates, ethylene oxide-modified nonylphenol (meth) acrylates, propylene oxide-modified nonylphenol (meth) acrylates, methoxydiethylene glycol (meth) acrylates, methoxypolyethylene glycol (meth) acrylates, methoxypropylene glycol (meth) acrylates, 2-(meth)acrylic acid acrylate, 2-hydroxy-3-phenoxypropyl phthalate, hydrogenated 2-(meth)acrylic acid acrylate, hydrogenated 2-(meth)acrylic acid acrylate (Meth)propenyl acrylate, hexahydrohydrogenated 2-(meth)propenyl acrylate, tetrahydrohydrogenated 2-(meth)propenyl acrylate, dimethylamine ethyl acrylate, trifluoroethyl acrylate, tetrafluoropropyl acrylate, hexafluoropropyl acrylate, octafluoropropyl acrylate, and adamantane derivatives of mono(meth)acrylates derived from 2-adamantane and adamantanediol, such as adamantane acrylates with a monovalent form.

[0037] Examples of difunctional (meth)acrylate compounds include: ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, butanediol dimethacrylate, hexanediol dimethacrylate, nonanediol dimethacrylate, ethylene glycol dimethacrylate oxyethylene oxide, ethylene glycol dimethacrylate propionate, diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, tripropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, ethylene glycol neopentyl glycol dimethacrylate, tripropylene glycol dimethacrylate, hydroxytrimethylacetic acid neopentyl glycol dimethacrylate, and other dimethacrylates.

[0038] Examples of trifunctional or higher (meth)acrylate compounds include: trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane trimethacrylate, propoxylated trimethylolpropane trimethacrylate, trimethylolpropane trimethacrylate, tri-2-hydroxyethyl triisocyanate trimethacrylate, glycerol trimethacrylate, neopentyltetrol trimethacrylate, dinepentyltetrol trimethacrylate, di-trimethylolpropane trimethacrylate, and other trifunctional (meth)acrylates. Compounds; and polyfunctional (meth)acrylate compounds with three or more functions, such as neopentyl tetroxide tetra(meth)acrylate, di-trimethylolpropane tetra(meth)acrylate, di-neopentyl tetroxide penta(meth)acrylate, di-trimethylolpropane penta(meth)acrylate, di-neopentyl tetroxide hexa(meth)acrylate, and di-trimethylolpropane hexa(meth)acrylate; and polyfunctional (meth)acrylate compounds formed by replacing a portion of these (meth)acrylates with alkyl groups or ε-caprolactones.

[0039] Furthermore, urethane (meth)acrylates can also be used as active energy line curing resins. Examples of urethane (meth)acrylates include those obtained by reacting a hydroxyl-containing (meth)acrylate monomer with an isocyanate monomer or prepolymer and a polyester polyol.

[0040] Examples of methacrylates include: neopentyl tert-acrylate hexamethylene diisocyanate methacrylate prepolymer, dinepentyl tert-acrylate hexamethylene diisocyanate methacrylate prepolymer, neopentyl tert-acrylate toluene diisocyanate methacrylate prepolymer, dinepentyl tert-acrylate toluene diisocyanate methacrylate prepolymer, neopentyl tert-acrylate isophorone diisocyanate methacrylate prepolymer, and dinepentyl tert-acrylate isophorone diisocyanate methacrylate prepolymer.

[0041] The aforementioned active energy line curable resin can be used in one form or in combination of two or more. Furthermore, the aforementioned active energy line curable resin and hard coating forming composition can be a monomer or a partially polymerized oligomer.

[0042] As photopolymerization initiators for compositions used in hard coating formation, examples include 2,2-ethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, dibenzoxyl, benzoin, benzoin methyl ether, benzoin ethyl ether, p-chlorobenzophenone, p-methoxybenzophenone, milchnerone, acetophenone, 2-chlorothiaxanone, etc. One of these can be used alone, or two or more can be used in combination.

[0043] Furthermore, solvents used in compositions for hard coating formation include: ethers such as dibutyl ether, dimethoxymethane, dimethoxyethylene, diethoxyethylene, propylene oxide, 1,4-dimethyl ether, 1,3-dioxolane, 1,3,5-trimethyl ether, tetrahydrofuran, anisole, and phenethyl ether; ketones such as acetone, methyl ethyl ketone, diethyl ketone, diacetone, diisobutyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and methylcyclohexanone; esters such as ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, n-pentyl acetate, and γ-butyrolactone; and selenosulfone derivatives such as methyl selenosulfone, selenosulfone, butyl selenosulfone, and selenosulfone acetate. These can be used alone or in combination of two or more.

[0044] Furthermore, to adjust the refractive index or impart hardness, the composition for forming a hard coating may also contain metal oxide microparticles. Examples of metal oxide microparticles include: zirconium oxide, titanium oxide, niobium oxide, antimony trioxide, antimony pentoxide, tin oxide, indium oxide, indium tin oxide, and zinc oxide.

[0045] Furthermore, the composition for forming the hard coating may also contain any of the following: silicon oxides, fluorinated silane compounds, fluoroalkyl silazanes, fluoroalkyl silanes, fluorinated silicon compounds, or silane coupling agents containing perfluoropolyether groups, which impart water-repellent and / or oil-repellent properties to improve stain resistance.

[0046] As other additives, leveling agents, defoamers, antioxidants, light stabilizers, photosensitizers, conductive materials, etc., can also be added to the composition for hard coating formation.

[0047] Anti-glare layer Anti-glare layers 24 and 25 have finely textured surfaces that scatter external light, thereby reducing the amount of external light entering the layer. Anti-glare layers 24 and 25 can be formed by coating an anti-glare layer forming composition containing an active energy line curable resin and, as needed, organic microparticles and / or inorganic microparticles, and then curing it. The active energy line curable resin used as the anti-glare layer forming composition can be the one described in hard coating layer 22. The film thickness of anti-glare layer 24 is not particularly limited, but is preferably 1 to 10 μm.

[0048] The organic microparticles used in the composition of the anti-glare layer are mainly materials that form fine irregularities on the surfaces of the anti-glare layers 24 and 25 to impart the function of diffusing external light. As organic microparticles, resin particles composed of light-transmitting resin materials such as acrylic resin, polystyrene resin, styrene-(meth)acrylate copolymer, polyethylene resin, epoxy resin, polysiloxane resin, polyvinylidene fluoride, and polydifluoroethylene resin can be used. To adjust the refractive index or the dispersibility of the resin particles, two or more resin particles of different materials (refractive indices) can also be mixed and used.

[0049] The inorganic microparticles used in the composition of the anti-glare layer are mainly materials used to adjust the sedimentation or aggregation of organic microparticles in the anti-glare layers 24 and 25. As inorganic microparticles, silica microparticles, metal oxide microparticles, and various mineral microparticles can be used. For example, colloidal silica or silica microparticles surface-modified with reactive functional groups such as (meth)acrylic acid can be used. For example, alumina, zinc oxide, tin oxide, antimony oxide, indium oxide, titanium dioxide, and zirconium dioxide can be used. For example, mica, synthetic mica, vermiculite, microcrystalline kaolinite, iron microcrystalline kaolinite, bentonite, aluminum bentonite, magnesium bentonite, lithium bentonite, talc, iron bentonite, sodium silicate, illite, sodium silicate hydrous, layered titanate, bentonite, and synthetic bentonite can be used. Mineral microparticles can be either natural or synthetic (including substituted compounds and derivatives), or a mixture of both. Layered organoclay is preferred among the mineral microparticles. Layered organoclay refers to clay formed by introducing organonium ions into the interlayer of bentonite. There are no restrictions on the organonium ions as long as they can be organically converted using the cation exchange capacity of bentonite. When using layered organoclay minerals as mineral microparticles, the aforementioned synthetic bentonite is suitable. Synthetic bentonite has the functions of increasing the viscosity of the coating liquid for forming the anti-glare layer, inhibiting the sedimentation of resin particles and inorganic microparticles, and adjusting the surface irregularities of the optical functional layer.

[0050] The composition for forming the anti-glare layer may also contain any of the following: silicon oxide, fluorinated silane compound, fluoroalkyl silazane, fluoroalkyl silane, fluorinated silicone compound, or silane coupling agent containing perfluoropolyether group. These materials can improve stain resistance by imparting water-repellent and / or oil-repellent properties to the anti-glare layer.

[0051] Anti-glare layers 24 and 25 can also be formed by unevenly distributing the material, resulting in layers with relatively high refractive index and relatively low refractive index sequentially stacked from the side of the colored layer 21. For example, anti-glare layers 24 and 25 formed by unevenly distributing the material can be formed by coating a composition containing a low-refractive-index material and a high-refractive-index material containing surface-modified silica microparticles or hollow silica microparticles, and then separating them by utilizing the difference in their surface free energies. When anti-glare layers 24 and 25 are formed as a phase-separated double layer, it is preferable that the refractive index of the layer with relatively high refractive index on the side of the colored layer 21 is 1.50 to 2.40, and the refractive index of the layer with relatively low refractive index on the surface side of the optical thin film 12 is 1.20 to 1.55.

[0052] <Low Refractive Index Layer> The low-refractive-index layer 23 can be formed by coating a low-refractive-index layer forming composition containing at least an active energy line curing resin and then curing it. The active energy line curing resin used in the low-refractive-index layer forming composition can be the one described in the hard coating layer 22. Microparticles such as LiF, MgF₂, 3NaF·AlF₃, AlF, and Na₃AlF₆, or silica microparticles, can also be incorporated into the low-refractive-index layer forming composition to adjust the refractive index. Furthermore, using porous silica microparticles or hollow silica microparticles, which have internal voids, is very effective for lowering the refractive index of the low-refractive-index layer. Additionally, photopolymerization initiators, solvents, and other additives described in the hard coating layer 22 can be appropriately incorporated into the low-refractive-index layer forming composition. The refractive index of the low-refractive-index layer 23 is preferably 1.20 to 1.55. Furthermore, the thickness of the low refractive index layer 23 is not particularly limited, but is preferably 40 nm to 1 μm.

[0053] The low refractive index layer 23 may also contain any of the following: silicon oxide, fluorinated silane compound, fluoroalkyl silazane, fluoroalkyl silane, fluorinated silicon compound, or silane coupling agent containing perfluoropolyether group. These materials can improve stain resistance by imparting water-repellent and / or oil-repellent properties to the low refractive index layer 23.

[0054] <Ultraviolet Absorption Layer> In the optical films 11-15 of the embodiments, in order to suppress the degradation of the pigment contained in the coloring layer 21, at least one ultraviolet absorbing layer having an ultraviolet absorber is provided on the functional layer deposited on the upper layer of the coloring layer 21. The ultraviolet shading rate of the ultraviolet absorbing layer is preferably 85% or more. Here, the ultraviolet shading rate is the value measured according to JIS L 1925 and can be calculated by the following formula. Ultraviolet (UV) shielding rate (%) = 100 - Average transmittance of UV rays with wavelengths of 290~400nm (%)

[0055] The ultraviolet absorbing layer can be formed by depositing any layer on the coloring layer 21 using a composition for forming an ultraviolet absorbing layer containing an ultraviolet absorber. In the examples of Figures 1 to 5, any one or more of the hard coating layer 22, the low refractive index layer 23, the anti-glare layers 24 and 25, and the oxygen barrier layer 26 contain an ultraviolet absorber, thereby performing the function of an ultraviolet absorbing layer.

[0056] As ultraviolet absorbers, compounds such as benzophenone, benzotriazole, triazine, anilide oxalate, and cyanoacrylate compounds can be used. The ultraviolet absorber is incorporated to suppress the degradation of the pigment contained in the coloring layer 21; therefore, it is used that absorbs light in the ultraviolet region at wavelengths that cause degradation of the pigment contained in the coloring layer 21. However, when curing the composition containing the ultraviolet absorber, if the ultraviolet absorption of the ultraviolet absorber is excessive, the curing of the composition becomes insufficient, resulting in insufficient surface hardness of the obtained optical film. Therefore, in this invention, by using an ultraviolet absorber with an absorption wavelength range in the ultraviolet region that differs from the absorption wavelength range of the photopolymerization initiator in the ultraviolet region, curing resistance when the ultraviolet absorber is present is suppressed. The absorption wavelength range of the ultraviolet absorber in the ultraviolet region is preferably in the range of 290-370 nm. When the absorption wavelength range of the ultraviolet absorber contained in any layer constituting the ultraviolet absorbing layer is set to this range, an oxyphosphine-based photopolymerization initiator with an absorption wavelength range different from this wavelength range can be used appropriately. Examples of oxyphosphine-based photopolymerization initiators include diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide or phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide. By making the absorption wavelength range of the ultraviolet absorber different from that of the photopolymerization initiator, the curing resistance during the formation of the ultraviolet absorbing layer containing the ultraviolet absorber can be suppressed, and the deterioration of the pigment contained in the coloring layer 21 after curing due to ultraviolet radiation can be suppressed.

[0057] To further suppress the degradation of the pigment contained in the coloring layer 21, the following configuration may be adopted.

[0058] <Oxygen barrier layer> The oxygen barrier layer 26 disposed on the optical thin film 15 in the fifth embodiment has an oxygen permeability of 10 cc / (m²·day·atm) or less, more preferably 5 cc / (m²·day·atm) or less, and even more preferably 1 cc / (m²·day·atm) or less. The oxygen barrier properties of the oxygen barrier layer 26 can suppress the oxidative degradation (fading) of the colorant contained in the coloring layer 21. The forming material of the oxygen barrier layer 26 preferably contains polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), vinylidene chloride, silicone resin, etc., and materials such as MAXIVE (registered trademark) manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC., EVAL manufactured by Kuraray Co., Ltd., Saran Latex and Saran Resin from Asahi Kasei Corporation can be used. Furthermore, the thickness of the oxygen barrier layer 26 is not particularly limited, as long as it is a thickness that achieves the desired oxygen barrier properties.

[0059] Furthermore, inorganic particles (particles composed of inorganic compounds) can also be dispersed in the oxygen barrier layer 26. These inorganic particles further reduce oxygen permeability and inhibit the oxidative degradation (fading) of the coloring layer 21. The size and content of the inorganic particles are not particularly limited, but can be appropriately set according to the thickness of the oxygen barrier layer 26. The size (maximum length) of the inorganic particles dispersed in the oxygen barrier layer 26 is preferably smaller than the thickness of the oxygen barrier layer 26; the smaller the better. In addition, the size of the inorganic particles dispersed in the oxygen barrier layer 26 can be uniform or non-uniform. Specifically, examples of inorganic particles dispersed in the oxygen barrier layer 26 include: silicon dioxide particles, aluminum oxide particles, silver particles, copper particles, titanium particles, zirconium dioxide particles, and tin particles.

[0060] The oxygen barrier layer 26 only needs to be deposited on the observer side, above the coloring layer 21. Furthermore, in the second embodiment of the optical thin film 12, an oxygen barrier layer can be further provided between the coloring layer 21 and the anti-glare layer 24. Furthermore, in the third embodiment of the optical thin film 13, an oxygen barrier layer can be further provided between the coloring layer 21 and the hard coating layer 22, or between the hard coating layer 22 and the anti-glare layer 25. Furthermore, in the fourth embodiment of the optical thin film 14, an oxygen barrier layer can be further provided between the coloring layer 21 and the anti-glare layer 24. By further providing an oxygen barrier layer, similar to the third embodiment, fading caused by pigment oxidation can be further suppressed.

[0061] <Contents for coloring layer formation> The aforementioned coloring layer 21 can be formed by coating a coloring layer forming composition containing an active energy line curing resin, a photopolymerization initiator, a pigment, a solvent, and additives to be blended as needed onto a transparent substrate 20 and then curing the coating. The active energy line curing resin, photopolymerization initiator, and solvent used in the coloring layer forming composition can be those described in the hard coating layer 22. Furthermore, as the pigment, a first color material and a second color material having the aforementioned absorption characteristics can also be used, and a third color material having the aforementioned absorption characteristics can be further blended as needed. As the additive, at least one of a free radical scavenger, a singlet oxygen quencher, and a peroxide decomposer can be used.

[0062] Free radical scavengers inhibit auto-oxidation by capturing free radicals generated during pigment oxidation and degradation, thus suppressing pigment deterioration (fading). Using hindered amine light stabilizers with a molecular weight of 2000 or higher as free radical scavengers yields superior fading inhibition. Low molecular weight free radical scavengers are more volatile, resulting in fewer molecules remaining in the colored layer and hindering sufficient fading inhibition. Suitable materials for use as free radical scavengers include, for example, Chimasorb 2020FDL and Chimasorb 944FDL from BASF, Tinuvin 622, and LA-63P from ADEKA.

[0063] Singlet oxygen quenchers function by deactivating highly reactive singlet oxygen, which readily causes pigment oxidation and deterioration (fading), thereby inhibiting pigment oxidation and deterioration (fading). Examples of singlet oxygen quenchers include transition metal complexes, pigments, amines, phenols, and sulfides. Particularly suitable materials are dialkyl phosphates, dialkyl dithiocarbamates, or transition metal complexes of benzene dithiophenol or similar dithiophenols. Nickel, copper, or cobalt can be used as the central metal.

[0064] Peroxide decomposing agents decompose the peroxides produced during pigment oxidation and deterioration, thereby stopping the auto-oxidation cycle and inhibiting pigment deterioration (fading). Phosphorus-based antioxidants and sulfur-based antioxidants can be used as peroxide decomposing agents.

[0065] Examples of phosphorus-based antioxidants include: 2,2'-methylenebis(4,6-di-tertiary-butyl-1-phenoxy)(2-ethylhexyloxy)phosphine, 3,9-bis(2,6-di-tertiary-butyl-4-methylphenoxy)-2,4,8,10-tetraoxazaspiro-3,9-diphosazaspiro[5.5]undecane, and 6-[3-(3-tertiary-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tertiary-butyldibenzo[d,f][1,3,2]dioxazine, etc.

[0066] Examples of sulfur-based antioxidants include: 2,2-bis({[3-(dodecylthio)propionic acid]oxy}methyl)-1,3-propanediyl-bis[3-(dodecylthio)propionate], 2-mercaptobenzimidazole, dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearate-3,3'-thiodipropionate, neopentyltetroxide-tetra(3-laurylthiopropionate), and 2-mercaptobenzothiazole.

[0067] As explained above, the optical films 11-15 of the present invention have, on one side of the transparent substrate 20, a coloring layer 21 containing a pigment with visible light absorption properties, and a functional layer containing an ultraviolet absorption layer. A portion of the external light incident on the optical films 11-15 is absorbed by the coloring layer 21 during its incidence on the display panel 10 and during its reflection from the display panel 10 and subsequent re-emission from the optical films 11-15, thus reducing the intensity of the reflected external light. This improves the contrast and visual recognizability of the displayed images on the display devices 1-5. Furthermore, by including an ultraviolet absorber in any of the functional layers constituting a layer above the coloring layer 21, pigment fading can be suppressed, thereby maintaining the display performance of the display devices 1-5.

[0068] Furthermore, when using the optical films 11-15 of the present invention, the transmittance of visible light of the optical film can be made to be 50% or more by selecting and doping the pigments. Therefore, the luminous intensity of the display panel 10 is not increased, and the brightness of the display device 1 can be improved compared to the conventional configuration using a circular polarizer. Also, since it is not necessary to increase the luminous intensity of the display panel 10 to improve brightness, the durability of the display panel 10 can be improved. Furthermore, the function of blocking visible light, as in the conventional circular polarizer, can be achieved by the thin film of the coloring layer 21, thus enabling a thinner display device 1-5 compared to the case of using a circular polarizer.

[0069] This invention can also be applied to compositions for forming ultraviolet (UV) absorbing layers, which are used to protect pigmented coloring layers. The composition for forming UV absorbing layers contains at least an active energy line curing resin, a photopolymerizable compound, a UV absorber, and a solvent. The UV absorber is selected from those whose absorption wavelength range differs from that of the photopolymerization initiator in the UV region and is in the range of 290-370 nm. By using this composition, a UV absorbing layer capable of inhibiting UV-induced degradation (fading) of the coloring layer can be formed.

[0070] In addition, an antifouling layer can be provided on the outermost surface of the optical thin film in each of the above embodiments. The antifouling layer improves the antifouling performance by imparting water-repellent and / or oil-repellent properties to the optical laminate, and can be formed by dry coating or wet coating of silicon oxides, fluorinated silane compounds, fluoroalkyl silazanes, fluoroalkyl silanes, fluorinated silicone compounds, silane coupling agents containing perfluoropolyether groups, etc.

[0071] Furthermore, an antistatic layer can also be provided on the optical thin film of each of the above embodiments. The antistatic layer can be formed by coating a coating liquid containing ionizing radiation-curing materials such as polyester acrylate monomers, epoxy acrylate monomers, urethane acrylate monomers, and polyol acrylate monomers, a polymerization initiator, and an antistatic agent, and then curing it by polymerization. As an antistatic agent, for example, antimony-doped tin oxide (ATO), tin-doped indium oxide (ITO), or other metal oxide microparticles, polymeric conductive components, quaternary ammonium salts, etc., can be used. The antistatic layer can be provided on the outermost surface of the optical laminate, or between the optical functional layer and the transparent substrate. Alternatively, the antistatic layer can be formed by incorporating an antistatic agent into any of the aforementioned functional layers. When an antistatic layer is provided, the surface resistivity of the optical thin film is preferably 1.0 × 10⁶ to 1.0 × 10¹² (Ω / cm).

[0072] Furthermore, in the optical thin films of embodiments 1, 4, and 5 above, a medium refractive index layer can be further provided to improve the performance of the antireflective layer. In this case, each layer can be sequentially deposited from the transparent substrate side in the order of medium refractive index layer, high refractive index layer (the layer that functions as a high refractive index layer), and low refractive index layer. The medium refractive index layer can be formed by coating a medium refractive index layer forming composition containing at least an active energy line curing resin onto a transparent substrate and then curing it. The active energy line curing resin used as the low refractive index layer forming composition can be the one described in the hard coating section. To adjust the refractive index, metal microparticles such as zirconium oxide, titanium oxide, niobium oxide, antimony trioxide, antimony pentoxide, tin oxide, indium oxide, indium tin oxide, and zinc oxide can also be incorporated into the medium refractive index layer forming composition. Furthermore, photopolymerization initiators, solvents, and other additives described in the hard coating section can also be appropriately incorporated into the medium refractive index layer forming composition.

[0073] Furthermore, in the optical thin film of the second embodiment described above, in order to improve the anti-reflection performance and display quality, an anti-reflection layer comprising a high refractive index layer and a low refractive index layer may be further provided on the anti-glare layer. [Example]

[0074] The following describes an embodiment. However, the present invention is not limited to the following embodiments.

[0075] In the following examples and comparative examples, optical thin films 1 to 14 with the layers shown in Tables 1A, 1B, and 2 were fabricated, and the characteristics of the fabricated thin films were evaluated. Furthermore, the display device characteristics of the organic EL display panel using optical thin films 1 to 14 were confirmed by simulation.

[0076] [Table 1A] Example 1 Example 2 Example 3 Example 4 Optical thin films Optical thin film 1 Optical thin film 2 Optical thin film 3 Optical thin film 4 Functional layer 1 Low refractive index layer 1 - Low refractive index layer 1 Low refractive index layer 1 Functional layer 2 Hard coating 1 Anti-glare layer 1 Hard coating 1 Hard coating 1 Functional layer 3 - - - - Color layer Color layer 1 Color layer 1 Color layer 2 Color layer 3 Substrate TAC TAC TAC TAC

[0077] [Table 1B] Example 5 Example 6 Example 7 Example 8 Optical thin films Optical thin film 5 Optical thin film 6 Optical thin film 8 Optical thin film 9 Functional layer 1 Low refractive index layer 1 Low refractive index layer 1 Low refractive index layer 1 - Functional layer 2 Hard coating 1 Hard coating 1 Hard coating 1 Hard coating 1 Functional layer 3 oxygen barrier layer 1 - - - Color layer Color layer 1 Color layer 6 Color layer 5 Color layer 1 Substrate TAC TAC TAC TAC

[0078] [Table 2] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Optical thin films Optical thin film 10 Optical thin film 11 Optical thin film 12 Optical thin film 13 Optical thin film 14 Functional layer 1 Low refractive index layer 1 Low refractive index layer 1 Low refractive index layer 1 - Low refractive index layer 1 Functional layer 2 Hard coating 2 Hard coating 2 Hard coating 3 Hard coating 2 Hard coating 2 Functional layer 3 - - - - - Color layer Color layer 1 Color layer 4 Color layer 1 Color layer 1 - Substrate TAC TAC TAC TAC TAC

[0079] <Fabrication of Optical Thin Films> The following explains the formation method of each layer.

[0080] [Formation of the coloring layer] (Materials used in the composition for forming the coloring layer) The following materials are used as components for forming a color layer. In addition, the maximum absorption wavelength and full width at half maximum (FWHM) of the colorant are calculated as characteristic values ​​in the hardened coating by using spectral transmittance. ･1st color material: Dye-1 is a pyrrole-methylene cobalt complex dye as shown in Formula 1 below (maximum absorption wavelength 493 nm, full width at half maximum 26 nm). ･Second color material: Dye-2 is a tetraazaporphyrin copper complex dye (manufactured by Yamada Chemical Co., Ltd., FDG-007, maximum absorption wavelength 595nm, full width at half maximum 22nm). Dye-3 is a tetrazaporphyrin copper complex dye (PD-311S manufactured by Yamamoto Chemical Co., Ltd., with a maximum absorption wavelength of 586 nm and a full width at half maximum (FWHM) of 22 nm). ･Third color material: Dye-4 is a copper phthalocyanine complex dye (manufactured by Yamada Chemical Co., Ltd., FDN-002, with a maximum absorption wavelength of 800nm). ·additive: Hindered amine light stabilizer Chimassorb 944FDL (manufactured by BASF JAPAN, molecular weight 2000~3100) Hindered amine light stabilizer Tinuvin 249 (manufactured by BASF JAPAN, molecular weight 482) Singlet oxygen quencher D1781 (manufactured by Tokyo Chemical Industry Co., Ltd.) • Ultraviolet absorber: Tinuvin479 (manufactured by BASF JAPAN, maximum absorption wavelength 322nm) LA-36 (manufactured by ADEKA, maximum absorption wavelengths 310nm and 350nm) • Active energy line curing resin: UA-306H (manufactured by Kyoeisha Chemical Co., Ltd., neopentyl terephthalate triacrylate hexamethylene diisocyanate carbamate prepolymer) DPHA (Dipentaerythritol Hexaacrylate) PETA (neoprene tetraacrylate) • Initiator: Omnirad TPO (manufactured by IGM Resing BV, absorption peak wavelength 275nm, 379nm) Solvent: MEK (Methyl Ethyl Ketone) Methyl acetate

[0081] (Chemistry 1)

[0082] (Formation of the coloring layer) As a transparent substrate, a 60 μm thick triacetyl cellulose film was used. The coloring layer composition shown in Table 3 was coated onto one side of the transparent substrate and dried in an oven at 80°C for 60 seconds. Subsequently, the coating was cured by ultraviolet irradiation with an irradiation linearity of 150 mJ / cm² (manufactured by Fusion UV Systems Japan KK, light source H bulb), forming coloring layers 1 to 6 with a cured film thickness of 5.0 μm. Furthermore, the addition amount was by mass ratio.

[0083] [Table 3] Color layer 1 Color layer 2 Color layer 3 Color layer 4 Color layer 5 Color layer 6 color material 1st color material Dye-1 Added amount 0.2% 0.2% 0.2% 0.2% 0.2% 0.2% 2nd color material Dye-2 / Dye-3 ratio 60 / 40 Added amount 0.5% 0.5% 0.5% 0.5% 0.5% 0.4% 3rd color material - - - - - Dye-4 Added amount - - - - - 1.3% additive type - Chimassorb 944FDL Chimassorb 944FDL / D1781 - Tinuvin 249 Chimassorb 944FDL / D1781 ratio - 100 67 / 33 - 100 67 / 33 Added amount - 1.4% 2.2% - 1.4% 3.2% UV absorber type - Tinuvin 479 / LA36 - - ratio - 40 / 60 - - Added amount - 3.20% - - Active energy line hardening resin type UA-306H / DPHA / PETA ratio 70 / 20 / 10 Added amount 44.7% 43.3% 42.5% 41.5% 43.3% 40.3% Photopolymerization initiator type Omnirad TPO Added amount 4.6% solvent type MEK / methyl acetate ratio 50 / 50 Added amount 50%

[0084] [Form of Functional Layers] • Oxygen barrier layer composition: PVA117 (manufactured by KURARAY) 80% aqueous solution

[0085] (Formation of an oxygen barrier layer) The above-mentioned composition for forming oxygen barrier layer is applied onto the coloring layer and dried to form oxygen barrier layer 1 of Table 1B with an oxygen permeability of 1cc / m²·day·atm.

[0086] (Composition for forming hard coating) The following materials are used as components for forming hard coatings. • Ultraviolet absorber: Tinuvin479 (manufactured by BASF JAPAN, maximum absorption wavelength 322nm) LA-36 (manufactured by ADEKA, maximum absorption wavelengths 310nm and 350nm) • Active energy line curing resin: UA-306H (manufactured by Kyoeisha Chemical Co., Ltd., neopentyl terephthalate triacrylate hexamethylene diisocyanate carbamate prepolymer) DPHA (Dipentaerythritol Hexaacrylate) PETA (neoprene tetraacrylate) • Initiator: Omnirad TPO (manufactured by IGM Resins BV, absorption peak wavelength 275nm, 379nm) Omnirad 184 (manufactured by IGM Resins BV, peak absorption wavelength 243nm, 331nm) Solvent: MEK (Methyl Ethyl Ketone) Methyl acetate

[0087] (Hard coating formation) The hard coating composition shown in Table 4 was applied to a colored layer or a transparent substrate and dried in an oven at 80°C for 60 seconds. Then, the coating was hardened by irradiation with ultraviolet light at a linear intensity of 150 mJ / cm² using a UV irradiation device (manufactured by Fusion UV Systems Japan KK, light source H bulb), forming hard coatings 1-3 of Tables 1A, 1B and 2 with a hardened film thickness of 5.0 μm.

[0088] [Table 4] Hard coating 1 Hard coating 2 Hard coating 3 UV absorber type Tinuvin479 / LA36 - Tinuvin479 / LA36 ratio 40 / 60 - 40 / 60 Added amount 3.2% - 3.2% Active energy line hardening resin type UA-306H / DPHA / PETA ratio 70 / 20 / 10 Added amount 42.2% 45.4% 42.2% Photopolymerization initiator type Omnirad TPO Omnirad 184 Added amount 4.6% solvent type MEK / methyl acetate ratio 50 / 50 Added amount 50.0%

[0089] (Composition for forming anti-glare layer) The following materials are used as components for forming the anti-glare layer. • Ultraviolet absorber: Tinuvin479 (manufactured by BASF JAPAN, maximum absorption wavelength 322nm) LA-36 (manufactured by ADEKA, maximum absorption wavelengths 310nm and 350nm) • Active energy line curing resin: LIGHT ACRYLATE PE-3A (manufactured by Kyoei Chemical Co., Ltd., refractive index 1.52) Photopolymerization initiator: Omnirad TPO (manufactured by IGM Resins BV, absorption peak wavelength 275nm, 379nm) • Resin particles: Styrene-methyl methacrylate copolymer particles (refractive index 1.515, average particle size 2.0 μm) Inorganic microparticles 1: Synthetic bentonite Inorganic microparticles 2: Alumina nanoparticles, average particle size 40nm Solvent Toluene Isopropanol

[0090] (Formation of the anti-glare layer) On the colored layer, the composition for forming the anti-glare layer 1 shown in Table 5 is applied to the layer composition in Table 1A, and dried in an oven at 80°C for 60 seconds. Then, the coating is hardened by irradiation with ultraviolet light at a linear intensity of 150 mJ / cm2 using an ultraviolet irradiation device (manufactured by Fusion UV Systems Japan KK, light source H bulb), forming the anti-glare layer 1 of Table 1A with a hardened film thickness of 5.0 μm.

[0091] [Table 5] Anti-glare layer 1 UV absorber type Tinuvin479 / LA36 ratio 40 / 60 Added amount 3.20% Active energy line hardening resin type PE-3A Added amount 40.5% Organic microparticles type Styrene-methyl methacrylate copolymer particles Added amount 0.5% Inorganic microparticles type Synthetic bentonite / alumina nanoparticles ratio 20 / 80 Added amount 1.25% Photopolymerization initiator type Omnirad TPO Added amount 4.55% solvent type Toluene / Isopropanol ratio 30 / 70 Added amount 50%

[0092] (Composition for forming low refractive index layers) The following materials are used as components for forming the low refractive index layer 1. • Refractive index adjuster: Porous silica microparticle dispersion (average particle size 75 nm, solid content 20%, solvent methyl isobutyl ketone) 8.5 parts by weight • Antifouling agent: OPTOOL AR-110 (manufactured by Daikin Industries, Ltd., 15% solids, solvent methyl isobutyl ketone) 5.6 parts by weight • Active energy line curing resin: 0.4 parts by weight of neopentyltetraol triacrylate • Initiator: Omnirad 184 (manufactured by IGM Resins BV) 0.07 parts by weight Leveling agent: RS-77 (manufactured by DIC) 1.7 parts by weight Solvent: 83.73 parts by weight of methyl isobutyl ketone

[0093] (Formation of a low-refractive-index layer) The composition for forming the low refractive index layer 1 of the above composition was coated onto the hard coating and dried in an oven at 80°C for 60 seconds. Then, the coating was hardened by irradiation with ultraviolet light using an ultraviolet irradiation device (Fusion UV Systems Japan KK, light source H bulb) at an irradiation linearity of 200 mJ / cm2, forming the low refractive index layers of Table 1A, Table 1B and Table 2 with a hardened film thickness of 100 nm.

[0094] [Thin Film Property Evaluation] (UV shielding rate) Using cellophane tape according to the JIS-K5600 adhesion test, the ultraviolet absorption layer formed on the colored layer of the obtained optical film was peeled off from the colored layer. Using an automatic spectrophotometer (Hitachi, Ltd., U-4100), with the adhesive tape as a reference, the transmittance of a single layer of ultraviolet absorption layer was measured, the average transmittance of the ultraviolet region (290~400nm) was calculated, and the ultraviolet shielding rate shown in Equation (1) was calculated. Equation (1) UV shielding rate (%) = 100 - Average transmittance (%) in the UV region (290~400nm)

[0095] (Pencil Hardness Test) For the surface of optical thin films, a Clemen scratch hardness tester (TESTER SANGYO Co., Ltd., HA-301) was used according to JIS-K5400-1990. A pencil (Mitsubishi Pencil Co., Ltd. UNI, pencil hardness H) with a 500g load was used for testing. The appearance changes caused by the damage were visually evaluated. Cases where no damage was observed were marked as ○, and cases where damage was observed were marked as ×.

[0096] (Lightfastness test) The reliability test of the optical thin film containing the obtained colored layer was conducted using a xenon weathering tester (Suga Test Instrument Co. Ltd., X75). The test was performed for 120 hours under xenon lamp illuminance of 60 W / cm² (300~400 nm), internal temperature of 45°C, and humidity of 50% RH. Transmittance was measured before and after the test using an automatic spectrophotometer (Hitachi, Ltd., U-4100). The transmittance difference ΔTλ1 (representing the minimum transmittance before the test at wavelength λ1 in the wavelength range of 470~530 nm), the transmittance difference ΔTλ2 (representing the minimum transmittance before the test at wavelength λ2 in the wavelength range of 560~620 nm), and the color difference ΔEab of the C light source before and after the test were calculated. A transmittance difference and color difference close to zero are preferred, with ΔEab ≤ 5 being more desirable.

[0097] [Display Device Characteristic Evaluation] (Penetration characteristics) The transmittance of the optical thin film was measured using an automatic spectrophotometer (Hitachi, Ltd., U-4100), and the light efficiency passing through the optical thin film during white display was calculated using this transmittance as an evaluation of the white display transmittance characteristics. As a benchmark, the spectral efficiency of the white display output when transmitting through the white organic EL light source and color filter shown in Figure 6 was set to 100.

[0098] (reflective properties) The transmittance of the optical thin film was measured using an automatic spectrophotometer (manufactured by Hitachi, Ltd., U-4100). The reflectance of the display panel was taken as 40%, the surface reflectance R when the low refractive index layer or anti-glare layer on the optical thin film was placed on the outermost layer of the observation side was taken as 1%, and the surface reflectance R when it was not placed was taken as 4%. The interface reflection and surface reflection in other layers were not considered. When the reflection value of the display device to the D65 light source in the state without the optical thin film was set to 100, the relative reflection value was calculated according to formula (2) and used as the evaluation of the reflection characteristics of the display device.

[0099] (Color reproduction) The transmittance of the optical thin film was measured using an automatic spectrophotometer (Hitachi, Ltd., U-4100). Furthermore, light from a white EL light source, as shown in Figure 6, was incident on a color filter, and the red, green, and blue display spectra output through the color filter (Figure 7) were measured. The NTSC ratio was calculated from the measured transmittance and the CIE 1931 chromaticity values ​​derived from the red, green, and blue display spectra in Figure 7. The NTSC ratio was used as an indicator of color reproducibility for evaluation.

[0100] Tables 6A, 6B, and 7 show the results of ultraviolet shielding rate, pencil hardness, and lightfastness tests of the ultraviolet absorption layer as characteristic evaluations of optical thin films, and also show the white display transmission characteristics, display device reflection characteristics, and color reproduction as characteristic evaluations of display devices.

[0101] As shown in Tables 6A, 6B, and 7, the reflectivity of display devices with a color layer is significantly reduced. Furthermore, while the transmittance of the circular polarizer is halved, the luminance efficiency of display devices with a color layer is still excellent, as indicated by the evaluation values ​​for white display transmittance characteristics, and color reproduction is also improved.

[0102] Furthermore, by placing the ultraviolet absorption function, as in Comparative Example 2, on top of the coloring layer instead of within it, the lightfastness of the coloring layer is significantly improved. Moreover, by using a laminated oxygen barrier layer and incorporating a high-molecular-weight hindered amine light stabilizer as a free radical scavenger and a nickel dithiocarbamate complex as a singlet oxygen quencher within the coloring layer, the lightfastness is further improved.

[0103] Furthermore, the ultraviolet-absorbing layer can also possess hardness by offsetting the absorption wavelength bands of the ultraviolet absorber and the photopolymerization initiator.

[0104] [Table 6A] Example 1 Example 2 Example 3 Example 4 UV absorption layer Hard coating 1 Anti-glare layer 1 Hard coating 1 Hard coating 1 UV shielding rate 90.5% 90.4% 90.5% 90.5% Pencil hardness ○ ○ ○ ○ Lightfastness of the coloring layer ⊿Tλ1 21.8 21.4 13.1 11.1 ⊿Tλ2 7.5 7.0 6.8 5.8 ⊿Eab 4.8 4.7 3.1 2.9 White display transparency characteristics 62.7 62.9 63.0 62.5 Comparative Example 5 69% 69% 69% 68% Reflective characteristics of display devices 15.2 15.1 15.5 15.1 Comparative Example 5 45% 45% 46% 45% Color reproduction NTSC ratio 98.6% 98.4% 98.4% 98.9%

[0105] [Table 6B] Example 5 Example 6 Example 7 Example 8 UV absorption layer Hard coating 1 Hard coating 1 Hard coating 1 Hard coating 1 UV shielding rate 90.5% 90.5% 90.5% 90.5% Pencil hardness ○ ○ ○ ○ Lightfastness of the coloring layer ⊿Tλ1 5.9 12.0 20.8 21.9 ⊿Tλ2 6.3 6.0 6.4 7.6 ⊿Eab 1.4 3.2 4.8 4.8 White display transparency characteristics 62.3 59.1 63.7 61.4 Comparative Example 5 68% 65% 70% 67% Reflective characteristics of display devices 15.0 13.6 15.6 16.6 Comparative Example 5 44% 40% 46% 49% Color reproduction NTSC ratio 98.6% 97.9% 98.2% 98.5%

[0106] [Table 7] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 UV absorption layer - - Hard coating 3 - - UV shielding rate - - 90.5% - - Pencil hardness ○ ○ × ○ ○ Lightfastness of the coloring layer ⊿Tλ1 43.0 49.1 21.5 43.1 - ⊿Tλ2 49.7 29.5 12.0 49.5 - ⊿Eab 13.7 10.6 4.4 13.8 - White display transparency characteristics 63.0 62.3 62.5 61.7 91.4 Comparative Example 5 69% 68% 68% 68% 100% Reflective characteristics of display devices 15.4 15.1 15.7 16.8 33.8 Comparative Example 5 46% 45% 46% 50% 100% Color reproduction NTSC ratio 98.5% 98.6% 98.6% 98.5% 91.7% [Potential for industrial application]

[0107] This invention can be applied to optical thin films used in display devices.

[0108] 1,2,3,4,5: Display devices 10: Display Panel 11, 12, 13, 14, 15: Optical thin films 20: Transparent substrate 21: Shading layer 22: Hard coating 23: Low Refractive Index Layer 24, 25: Anti-glare layer 26: Oxygen barrier layer

Claims

1. An optical thin film, characterized by comprising: a transparent substrate; a coloring layer deposited on one side of the transparent substrate and containing a pigment; and a functional layer deposited on the coloring layer; wherein the pigment comprises: a first colorant having a maximum absorption wavelength in the range of 470–530 nm and a half-width at half-maximum (WHM) of the absorption spectrum of 15–45 nm; and a second colorant having a maximum absorption wavelength in the range of 560–620 nm and a WHM of the absorption spectrum of 15–55 nm; the functional layer comprising an ultraviolet absorbing layer having an ultraviolet shielding rate of 85% or higher according to JIS L 1925, and its surface having a pencil hardness of H or higher under a 500g load.

2. The optical thin film of claim 1, wherein the colored layer contains one or more of a free radical scavenger, a peroxide decomposer, and a singlet oxygen quencher.

3. The optical film of claim 2, wherein the free radical scavenger is a hindered amine light stabilizer with a molecular weight of 2000 or more.

4. The optical thin film of claim 2, wherein the singlet oxygen quencher is a dialkyl phosphate, a dialkyl dithiocarbamate, or a transition metal complex of benzodithiophenol.

5. The optical film of any one of claims 1 to 4, wherein the functional layer comprises an oxygen barrier layer having an oxygen permeability of less than 10 cc / m2·day·atm.

6. The optical film of any one of claims 1 to 4, wherein the ultraviolet absorbing layer comprises a hardened film containing a composition of an energy line hardening compound, a photopolymerization initiator and an ultraviolet absorber, wherein the absorption wavelength range of the photopolymerization initiator in the ultraviolet region is different from that of the ultraviolet absorber in the ultraviolet region, and the absorption wavelength range of the ultraviolet absorber in the ultraviolet region is in the range of 290 to 370 nm.

7. An optical thin film as claimed in any one of claims 1 to 4, wherein the functional layer comprises, from the side of the colored layer, the ultraviolet absorbing layer and a low refractive index layer with a refractive index lower than that of the ultraviolet absorbing layer.

8. The optical film of any one of claims 1 to 4, wherein the functional layer comprises, from the side of the colored layer, the ultraviolet absorption layer and the anti-glare layer in sequence.

9. The optical film of any one of claims 1 to 4, wherein the ultraviolet absorbing layer is an anti-glare layer containing an ultraviolet absorber.

10. An optical film as claimed in any one of claims 1 to 4, wherein the functional layer, from the side of the colored layer, sequentially comprises the ultraviolet absorbing layer and a low refractive index layer with a refractive index lower than that of the ultraviolet absorbing layer, the ultraviolet absorbing layer being an anti-glare layer containing an ultraviolet absorber.

11. An optical thin film as claimed in any one of claims 1 to 4, wherein the pigment contained in the coloring layer contains one or more compounds selected from the group consisting of compounds having any one of porphyrin, anthocyanin, phthalocyanine, azo, anthocyanin, squaric acid cyanide, coumarin, polyene, quinone, tetra-diporphyrin, pyrromethene, and indigo structures, and their metal complexes.

12. The optical film of any one of claims 1 to 4, wherein the pigment further comprises a third color material with a maximum absorption wavelength in the range of 650 to 900 nm.

13. A display device comprising an optical thin film as claimed in any one of claims 1 to 12.

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