TWI684797B - Optical laminate, polarizing plate, and display apparatus - Google Patents

Abstract

Provided is an optical laminate, and a polarizing plate and a display device using the same. The optical laminate system has excellent durability, suppressed rainbow spots and high visibility, and can be made thin. The optical laminate 1 is one in which an undercoat layer 3 and an anti-glare layer 4 having a concave-convex shape on the surface are sequentially provided on at least one surface of the transparent substrate 2. The transparent base material 2 contains polyethylene terephthalate, the in-plane retardation amount is 600 nm or less, and the thickness direction retardation amount is 3000 nm or more.

Description

Optical laminate, polarizing plate and display device

The present invention relates to an optical laminate suitable for an anti-glare film, and a polarizing plate and display device using the same.

In display members such as liquid crystal display panels and touch panels, optical laminates such as optical laminates, antireflection films, and antiglare films are used. As a transparent substrate constituting an optical laminate, a cellulose ester-based film such as cellulose triacetate, which is excellent in transparency and optical isotropy, has hitherto been used. However, the cellulose ester-based film has durability, especially moisture resistance and The shortcoming of insufficient heat resistance. Therefore, various reviews have been conducted to use polyethylene terephthalate (PET) films instead of cellulose ester-based films as transparent substrates. The PET film has the advantages of being excellent in transparency, moisture resistance, heat resistance, and mechanical strength and being inexpensive.

However, because polyethylene terephthalate has an aromatic ring in its molecular structure, birefringence occurs in the plane of the PET film. If an optical laminate using a PET film as a transparent substrate is laminated on a polarizing film On the top, there will be uneven color like rainbow (hereinafter referred to as "rainbow spot").

As a technique for eliminating rainbow spots generated when PET is used as a transparent substrate, for example, there is the one described in Japanese Patent No. 5556926. In Japanese Patent No. 5556926, the use of a polyester base material with an in-plane retardation (Re) of 3000 nm or more improves rainbow spots when used in a display device.

As the thickness and weight of display devices have decreased in recent years, the optical laminate is required to be thinner, and the transparent substrate used in the optical laminate is required to be thinner. However, if the in-plane retardation amount of the PET film is increased as described in Japanese Patent No. 5556926 in order to suppress the rainbow spots generated when the PET film is used, the thickness of the PET film must also increase. That is, when a PET film with a high retardation amount is used as a transparent substrate, it becomes difficult to reduce the thickness.

Therefore, an object of the present invention is to provide an optical laminate, and a polarizing plate and a display device using the same. The optical laminate system has excellent durability, suppressed rainbow spots and high visibility, and can be made thin.

The optical laminate of the present invention is provided with an undercoat layer on at least one surface of a transparent substrate containing polyethylene terephthalate with an in-plane retardation of 600 nm or less and a thickness direction retardation of 3000 nm or more , And the anti-glare layer with a concave-convex shape on the surface, the haze of the optical laminate is 0.5 to 50%.

In addition, the polarizing plate of the present invention is characterized in that a polarizing substrate is laminated on the transparent base material constituting the optical laminate.

In addition, the display device of the present invention is characterized by including the above-mentioned optical laminate.

According to the present invention, it is possible to provide an optical laminate, a polarizing plate and a display device using the optical laminate system. The optical laminate system has excellent durability, suppressed rainbow spots and interference fringes and high visibility, and can be made thin.

These and other objects, features, situations, and effects of the present invention will become more apparent from the following detailed description by referring to the accompanying drawings.

1‧‧‧ optical laminate

2‧‧‧Transparent substrate

3‧‧‧ Primer coating

4‧‧‧Anti-glare layer

6‧‧‧Functional layer

FIG. 1 is a cross-sectional view schematically showing an example of the optical laminate in the embodiment.

2 is a cross-sectional view schematically showing another example of the optical layered body of the embodiment.

Fig. 1 is a schematic cross-sectional view of an optical laminate according to an embodiment.

The optical layered body 1 is one in which a primer layer 3 and an anti-glare layer 4 are sequentially stacked on one side of a transparent substrate 2.

(Transparent substrate)

The transparent substrate 2 is a thin film that becomes the base of the optical laminate 1. The thickness of the transparent substrate 2 is preferably 12-40 μm. If the thickness of the transparent substrate 2 is less than 12 μm, the transparent substrate 2 becomes too thin, and the hardness of the antiglare layer 4 and the strength of the optical laminate 1 decrease. On the other hand, if the thickness of the transparent base material 2 exceeds 40 μm, the optical laminate 1 becomes thick, and therefore it does not contribute to the thinning of the display member using the optical laminate 1.

As the transparent substrate 2, a polyethylene terephthalate film (PET film) having an in-plane retardation amount (Re) of 600 nm or less and a thickness direction retardation amount (Rth) of 3000 nm or more is used. By using a PET film with an in-plane retardation amount and a thickness direction retardation amount within this range, it is possible to suppress rainbows when the optical laminate 1 is superimposed on a polarizing plate, or when a polarizer is provided on the optical laminate 1 And the thin film of the transparent substrate 2 can be realized. When the in-plane retardation exceeds 600 nm, the thickness of the transparent substrate 2 is thicker than the 40 μm described above, which is not preferable. In addition, when the retardation in the thickness direction is less than 3000 nm, the hardness of the anti-glare layer 4 when constituting the optical laminate 1 decreases, which is not preferable. The upper limit of the amount of retardation in the thickness direction of the transparent substrate 2 is not particularly limited, but it is preferably 8000 nm or less.

In addition, since the PET film is low in moisture permeability (water vapor barrier property), transparency, heat resistance, and mechanical strength, it can be used as a transparent substrate 2 to improve the durability of the optical laminate 1. In addition, PET film is cheap, so it is also advantageous in terms of manufacturing cost. The polyvinyl alcohol (PVA) film used in the polarizing plate is highly hygroscopic and swells due to moisture absorption and changes in size. Therefore, in order to protect it from moisture, a protective film is generally laminated on both sides. Since the optical laminate 1 of the present embodiment uses a PET film having water vapor barrier properties (low moisture permeability) as the transparent substrate 2, it is particularly suitable as a protective film for polarizing plates.

In addition, in order to improve the adhesion to the undercoat layer 3 and the anti-glare layer 4, the transparent substrate 2 may be subjected to surface modification treatment. Examples of the surface modification treatment include alkali treatment, corona treatment, plasma treatment, sputtering treatment, coating of surfactants, silane coupling agents, and the like, and Si vapor deposition.

(Undercoat)

The undercoat layer 3 has a function as an easy adhesion layer that improves the adhesion of the anti-glare layer 4 to the transparent substrate 2. The undercoat layer 3 is formed by, for example, applying a composition for forming an undercoat layer containing at least an active energy ray-curable resin to the surface of the transparent substrate 2 and hardening it. The thickness of the undercoat layer 3 is preferably 40 to 120 nm.

(Anti-glare layer)

The surface of the anti-glare layer 4 has a fine uneven shape, and mainly provides the optical laminate 1 with anti-glare properties. The anti-glare layer 4 can be formed on the surface of the undercoat layer 3 by hardening an anti-glare layer forming composition containing active energy ray-curable resin and fine particles, for example. The thickness of the anti-glare layer 4 is preferably 1-20 μm. If the thickness of the anti-glare layer 4 is less than 1 μm, the hardness of the anti-glare layer 4 is insufficient. On the other hand, if the thickness of the anti-glare layer 4 exceeds 20 μm, the thickness of the optical laminate 1 becomes thicker, and thus it does not contribute to the thinning of the display member using the optical laminate 1.

The active energy ray-curable resin used for the undercoat layer 3 and the anti-glare layer 4 is a resin that is polymerized and cured by irradiation with active energy rays such as ionizing radiation, ultraviolet rays, etc. For example, monofunctional, bifunctional, or 3 can be used More than functional (meth)acrylate monomer. In addition, in this specification, "(meth)acrylate" is a general term of both acrylate and methacrylate, "(meth)acryloyl" is both acryl and methacryl Collectively.

As a resin material that is hardened by the irradiation of ionizing radiation, it can be used alone or in combination: it has a radical polymerizable functional group such as an acryloyl group, methacryloyl group, acryloyloxy group, and methacryloyloxy group. Monomers, oligomers, and prepolymers of cationic polymerizable functional groups such as epoxy groups, vinyl ether groups, and oxetane groups. Examples of monomers include methyl acrylate, methyl methacrylate, methoxypolyvinyl methacrylate, cyclohexyl methacrylate, phenoxyethyl methacrylate, and ethylene glycol dimethacrylate. Ester, dipentaerythritol hexaacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, etc. Examples of oligomers and prepolymers include polyester acrylates, polyurethane acrylates, polyfunctional urethane acrylates, epoxy acrylates, polyether acrylates, and alkyd acrylates. , Acrylate compounds such as melamine acrylate, silicone acrylate, unsaturated polyester, tetramethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, bisphenol A di Epoxy compounds such as glycidyl ether, various alicyclic epoxy compounds, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis{[(3-ethyl-3-oxo Heterocyclic compounds such as heterocyclobutyl)methoxy]methyl}benzene and di[1-ethyl(3-oxetanyl)]methyl ether.

系、苯偶姻、苯偶姻甲基醚等的自由基聚合引發劑、芳香族重氮鹽、芳香族鋶鹽、芳香族錪鹽、茂金屬化合物等的陽離子聚合引發劑。 The above-mentioned resin material can be hardened by irradiating ultraviolet rays on condition that the photopolymerization initiator is added. As a photopolymerization initiator, it can be used alone or in combination: acetophenone series, benzophenone series, oxygen sulfur

System, benzoin, benzoin methyl ether and other free radical polymerization initiators, aromatic diazonium salts, aromatic cerium salts, aromatic iodonium salts, metallocene compounds and other cationic polymerization initiators.

The fine particles contained in the anti-glare layer 4 are substances added to form a fine uneven structure on the surface to exhibit anti-glare properties, and various inorganic fine particles and organic fine particles (fillers) can be used. However, the fine particles are not essential substances, and the fine particles can be omitted if they can be formed on the surface of the anti-glare layer 4 with a fine uneven shape required to exhibit anti-glare properties.

When inorganic fine particles are used as the fine particles added to the anti-glare layer 4, inorganic nano particles having an average particle diameter of 10 to 200 nm are preferred. The amount of inorganic fine particles added is preferably 0.1 to 5.0%.

As the inorganic fine particles, for example, swelling clay can be used. If the swelling clay has a cation exchange ability and a solvent is introduced into the layers of the swelling clay to swell, it may be natural or synthetic (including substitutions and derivatives). In addition, it may be a mixture of natural products and synthetic products. Examples of the swelling clay include mica, synthetic mica, vermiculite, montmorillonite, iron montmorillonite, beidellite, saponite, hectorite, attapulgite, attapulgite, and sodium maltosilicate Stone, illite, bernerite, layered titanate, bentonite, synthetic bentonite, etc. These swelling clays may be used alone or in combination. In addition, colloidal silica, alumina, and zinc oxide may be used alone or as a mixture of inorganic fine particles. In addition to the above-mentioned swelling clay, one or more kinds of colloidal silica, alumina, and zinc oxide may be used in combination.

As the inorganic fine particles, layered organic clay is more preferable. In the present invention, the layered organic clay refers to a substance that introduces organic onium ions into the layers of the swelling clay. The organic onium ion is not limited as long as it can utilize the cation exchangeability of the swelling clay to organicize. As the inorganic fine particles, for example, synthetic bentonite (layered organic clay mineral) can be used. Synthetic bentonite has a function as a thickener that increases the viscosity of the antiglare layer forming composition. The addition of synthetic bentonite as a thickener suppresses the precipitation of resin particles and inorganic fine particles, and contributes to the formation of the uneven structure on the surface of the anti-glare layer.

When using organic fine particles (filler) as the fine particles added to the anti-glare layer 4, it is possible to use acrylic resin, polystyrene resin, styrene-(meth)acrylate copolymer, polyethylene resin, epoxy resin , Silicone resin, polyvinylidene fluoride, polyvinyl fluoride resin and other light-transmissive resin material resin particles. In order to adjust the refractive index and the dispersion of the resin particles, two or more types of resin particles with different materials (refractive index) may be mixed and used. The resin particles (filler) are aggregated in the base resin (binder resin), and a fine uneven structure is formed on the surface of the anti-glare layer. Although it is also possible to impart a concave-convex structure required to exhibit anti-glare properties by forming a random aggregation structure in the anti-glare layer without blending resin particles, it is easy to adjust the anti-glare by including the resin particles in the anti-glare layer The size and number of irregularities on the surface of the layer.

烷、1,3-二氧環戊烷、1,3,5-三

、四氫呋喃、苯甲醚及苯乙醚、聚乙二醇甲基醚等的醚類；或丙酮、甲基乙基酮、二乙基酮、二丙基酮、二異丁基酮、甲基異丁基酮、環戊酮、環己酮、及甲基環己酮等的酮類；或甲酸乙酯、甲酸丙酯、甲酸正戊酯、 乙酸甲酯、乙酸乙酯、丙酸甲酯、丙酸乙酯、乙酸正戊酯、及γ-丁內酯等的酯類；另外，甲基賽路蘇、賽路蘇、丁基賽路蘇、賽路蘇乙酸酯等的賽路蘇類。它們可以單獨或合併2種以上使用。 In addition, a suitable solvent may be added to the composition for forming an undercoat layer or the composition for forming an anti-glare layer. Examples of the solvent include dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-bis

Alkanes, 1,3-dioxolane, 1,3,5-tris

, Tetrahydrofuran, anisole, phenyl ether, polyethylene glycol methyl ether and other ethers; or acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, methyl iso Ketones such as butyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone; or ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, Esters such as ethyl propionate, n-pentyl acetate, and γ-butyrolactone; in addition, cycloxol such as methyl thiolxyl, cyloxulan, butyl cyloxulan, cyloxol acetate, etc. class. These can be used individually or in combination of 2 or more types.

In addition, in the composition for forming an undercoat layer or the composition for forming an anti-glare layer, an antifouling agent, a surface adjusting agent, a leveling agent, a refractive index adjusting agent, a light sensitizer, Additives for conductive materials.

The optical layered body 1 of the present embodiment can be formed by applying a coating solution of the above-mentioned composition for forming an undercoat layer on at least one side of the transparent substrate 2 by a wet-coating method using a roll-to-roll method After irradiating the coating film with active energy rays such as electron rays and ultraviolet rays to harden the active energy ray-curable resin, the undercoat layer 3 is coated with the above-mentioned anti-glare layer forming composition by a wet coating method. The solution irradiates the coating film with active energy rays such as electron rays and ultraviolet rays to harden the active energy ray-curable resin. As the wet coating method, a flow coating method, a spray coating method, a roll coating method, a gravure roll coating method, an air doctor coating method (air doctor coating method), a blade coating method, a wire blade coating method, a knife coating can be used Known methods such as a method, a reverse coating method, a transfer roll coating method, a microgravure coating method, a kiss coating method, a casting coating method, a slit nozzle coating method, a calender coating method, and a die coating method. In addition, in the case where the coating film is cured by irradiating ultraviolet rays, in the case of irradiating ultraviolet rays, a high-pressure mercury lamp, a halogen lamp, a xenon lamp, a fusion lamp, or the like can be used. The ultraviolet radiation dose is usually about 100 to 800 mJ/cm ² .

Since the optical laminate 1 of the present embodiment uses a PET film as the transparent substrate 2, it has lower moisture permeability and is superior in water vapor barrier properties than cellulose acetate films such as triacetate cellulose. In addition, since the PET film is also excellent in heat resistance and mechanical strength, it can be used as a transparent substrate 2 to improve the durability of the optical laminate 1. In addition, since PET films are high in transparency and inexpensive, they are suitable as optical laminates for image display devices and the like.

Generally speaking, if an optical laminate using a PET film as the transparent substrate 2 is used in an image display device, rainbow spots due to the birefringence of PET itself are likely to occur. This rainbow spot becomes a factor that reduces the visibility of the image display device. However, in the optical laminate 1 of the present embodiment, by using a PET film having an in-plane retardation amount of 600 nm or less and a thickness direction retardation amount of 3000 nm or more as the transparent substrate 2, the generation of rainbow spots can be suppressed. It is possible to suppress interference fringes caused by a difference in refractive index with the anti-glare layer 4.

(Other modifications)

In the optical laminate 1 of the above embodiment, at least one other functional layer 6 such as a refractive index adjustment layer, an antistatic layer, and an antifouling layer may be provided on the antiglare layer 4 having irregularities on the surface.

2 is a cross-sectional view showing an example of an optical laminate 1 in which a low-refractive-index layer as a functional layer 6 is further provided on the anti-glare layer 4. The low refractive index layer is a refractive index adjustment layer for reducing the reflectance by reducing the refractive index of the surface. The low refractive index layer can be formed by coating ionization including polyester acrylate monomers, epoxy acrylate monomers, urethane acrylate monomers, polyol acrylate monomers, etc. The coating liquid of the radiation hardening material and the polymerization initiator hardens the coating film by polymerization. Can be used as low refractive particles including LiF, MgF, 3NaF. Low-refractive-index fine particles of low-refractive materials such as AlF or AlF (all having a refractive index of 1.4) or Na ₃ AlF ₆ (cryolite, refractive index of 1.33) are dispersed in the low-refractive-index layer. In addition, as the low-refractive-index fine particles, particles having voids inside the particles can be suitably used. In the case of particles having voids inside the particles, the void portion can be set to the refractive index of air (≒1), so it can be used as a low-refractive-index particle having a very low refractive index. Specifically, by using low-refractive-index silicon oxide particles having voids inside, the refractive index can be reduced.

The antistatic layer can be formed by applying ionizing radiation including polyester acrylate monomers, epoxy acrylate monomers, urethane acrylate monomers, polyol acrylate monomers, etc. The coating liquid of the curable material, the polymerization initiator, and the antistatic agent is cured by polymerization. As the antistatic agent, for example, metal oxide-based fine particles such as antimony-doped tin oxide (ATO), tin-doped indium oxide (ITO), polymer-type conductive composition, quaternary ammonium salt, etc. can be used. . The antistatic layer may be provided on the outermost surface of the optical laminate, or may be provided between the anti-glare layer and the translucent base.

The antifouling layer is provided on the outermost surface of the optical laminate, and the antifouling property is improved by imparting water repellency and/or oil repellency to the optical laminate. The antifouling layer can be dry-coated by applying silicon oxide, fluorine-containing silane compound, fluoroalkylsilazane, fluoroalkylsilane, fluorine-containing silicon compound, perfluoropolyether-containing silane coupling agent, etc. Or wet coating to form.

At least one of infrared absorption layer, ultraviolet absorption layer, color correction layer, etc. may be provided instead of the above-mentioned low refractive index layer, antistatic layer, antifouling layer, or in addition to the low refractive index layer, antistatic layer, antifouling Outside the layer, at least one layer of an infrared absorption layer, an ultraviolet absorption layer, a color correction layer, and the like may be provided.

In addition, in the optical laminate 1 of the present embodiment, it is preferable to form a random aggregation structure in the anti-glare layer 4.

The random agglomeration structure refers to a structure in which a first phase containing a relatively large amount of resin components (a binder component) and a second phase system containing a relatively large amount of inorganic components exist in three-dimensional disorder, and the second phase system Unevenly distributed around the fine particles (resin particles). By forming the random aggregation structure in the anti-glare layer 4, fine irregularities can be reduced, and therefore the anti-glare property and the blackness during black display can be improved. The random aggregation structure can be formed by, for example, the method described in Japanese Patent No. 5802043.

In addition, when a random aggregation structure is formed in the anti-glare layer 4, at least one layer of the aforementioned low refractive index layer, antistatic layer, anti-fouling layer, infrared absorption layer, and ultraviolet rays may be provided on the anti-glare layer 4 Functional layer 6 such as an absorption layer and a color correction layer.

Furthermore, the optical laminate 1 of the present embodiment can be used to configure a polarizing plate. Specifically, a polarizing film is formed by adsorbing iodine and a dye and aligning the PVA film, and attaching the optical layered body 1 of the present embodiment as a protective film on both sides of the polarizing film to form a polarizing plate. Alternatively, a polarizing layer can be formed by providing a polarizing layer on the other surface (the surface on which the anti-glare layer 4 is not provided) of the transparent base material 2 of the optical laminate 1 shown in FIG. 1 by a known method. In this case, the optical laminate 1 or other protective film may be further laminated on the polarizing layer. The polarizing layer can be formed by aligning the PVA film with iodine and dye, for example

In addition, the optical laminate 1 of the present embodiment can be used in combination with a liquid crystal panel or the like to constitute a display device. Examples of the configuration of the display device include those in which the optical layered body 1, polarizing plate, liquid crystal panel, polarizing plate, and backlight unit of the present embodiment are laminated in this order from the observation side. In addition, a touch sensor can be further laminated to form a display device with a touch sensor.

In addition, the optical layered body 1 of the present embodiment can be used as an optical layered body used in a display device such as a smartphone, tablet computer, notebook computer, etc., or a display device (touch panel) with a touch sensor. As the optical laminate, in addition to the optical laminate, the above-mentioned polarizing plate, anti-reflection film, anti-glare film, etc. may be mentioned. Specifically, the optical laminate 1 of the present embodiment can be used as a film provided on the outermost surface of a display panel such as a liquid crystal display device or a film provided on the outermost surface of a touch panel of an external or in-cell type. Or in a touch panel assembled by a direct bonding method or an air gap method, it is used as an intermediate film provided between the touch sensor and the display panel.

In addition, in the present embodiment, an example in which the undercoat layer 3 and the anti-glare layer 4 are provided on one side of the transparent base material 2 has been described. However, the undercoat layer 3 and the anti-glare layer may be provided on both sides of the transparent base material 2 4 Optical laminate.

[Example]

In the following, an embodiment of the present invention will be described. In addition, in the following Examples and Comparative Examples, an optical laminate in which an undercoat layer and an anti-glare layer are provided on a transparent substrate is prepared, but the optical laminate of the present invention is not limited to the three-layer film.

<Composition for forming undercoat layer>

The following materials were mixed to prepare a composition for forming an undercoat layer.

. Base resin

Trade name: UF8001G (non-yellowing type oligomeric urethane acrylate), Gongrongshe Chemical Co., Ltd. 0.85 parts by mass

. Polymerization initiator

Trade name: Irgacure (registered trademark) 184 (1-hydroxycyclohexyl phenyl ketone), BASF 0.04 parts by mass

. Solvent

<Composition for forming anti-glare layer>

The following materials were mixed to prepare compositions 1 to 4 for forming an anti-glare layer.

[Coating solution 1 for forming anti-glare layer]

. Base resin: UV/EB curable resin LIGHT-ACRYLATE PE-3A (pentaerythritol triacrylate, manufactured by Kyoeisha Chemical Co., Ltd.), refractive index 1.52 91.7 parts by mass

Moreover, the mixed solvent which mixed toluene and isopropyl alcohol in the ratio of 16:37 was used as a solvent.

[Coating solution 2 for forming antiglare layer]

Moreover, the mixed solvent which mixed toluene and isopropyl alcohol in the ratio of 16:37 was used as a solvent.

[Coating solution 3 for forming anti-glare layer]

In addition, toluene is used as a solvent.

[Coating solution 4 for forming antiglare layer]

In addition, toluene is used as a solvent.

<transparent substrate>

In Examples 1 to 7, Comparative Examples 1, 2 and 4, polyethylene terephthalate having the thickness, in-plane retardation (Re) and thickness direction retardation (Rth) shown in Table 1 ( PET) as a transparent substrate. In addition, in Comparative Example 3, a cellulose triacetate (TAC) film having a thickness shown in Table 1 was used as a transparent substrate.

<Preparation of optical laminate> (Examples 1 to 4, Comparative Examples 1, 2 and 4)

On one side of the transparent substrate, the coating liquid of the undercoat layer forming composition was applied and dried by a bar coating method, and then a metal halide lamp was used to irradiate ultraviolet rays at an irradiation dose of 200 mJ/m ² to harden the coating film. To form a primer layer. In addition, the application amount of the coating liquid for the undercoat layer forming composition is adjusted so that the thickness of the cured film becomes 40 nm.

Next, on the formed undercoat layer, the coating solution of the anti-glare layer forming composition 1 described above was applied and dried by a bar coating method, and then a metal halide lamp was used to irradiate ultraviolet rays at an irradiation dose of 200 mJ/m ² . Harden the coating to form an anti-glare layer. The coating amount of the antiglare layer forming composition 1 was adjusted so that the thickness of the cured film became the value shown in Table 1.

(Example 5)

An optical laminate was produced by the same method as Example 1 except that the coating liquid 2 for forming an anti-glare layer was used instead of the coating liquid 1 for forming an anti-glare layer.

(Example 6)

An optical laminate was produced by the same method as Example 1 except that the coating liquid 3 for forming an anti-glare layer was used instead of the coating liquid 1 for forming an anti-glare layer.

(Example 7)

An optical laminate was produced by the same method as Example 1 except that the coating liquid 4 for forming an anti-glare layer was used instead of the coating liquid 1 for forming an anti-glare layer.

(Comparative example 3)

On one side of the transparent substrate, without forming an undercoat layer, the coating solution of the above-mentioned anti-glare layer forming composition 1 was applied and dried by a bar coating method, and then a metal halide lamp was used to irradiate the light at 200 mJ/ m ^{2 is} irradiated with ultraviolet rays to harden the coating film to form an anti-glare layer. The coating amount of the antiglare layer forming composition coating liquid was adjusted so that the thickness of the cured film became the value shown in Table 1.

The optical laminates obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were evaluated for haze, clarity of transmitted image, pencil hardness, degree of rainbow spots, and moisture permeability. The evaluation method and evaluation criteria are as follows.

<haze>

The haze was measured according to JIS K7105 using a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.).

<Transparent image sharpness>

The transmission image sharpness was measured with an optical comb width of 0.5 mm using a sharpness measuring instrument (ICM-1T, manufactured by Suga Tester Co., Ltd.) according to JIS K7105.

<pencil hardness>

Based on JIS K5600 (4.9 N load), a pencil scratch tester (HA-301, Tester Industries Co., Ltd.) was used to measure the pencil hardness of the hard coat surface. When the measured pencil hardness is 2H or more, it is determined that the surface hardness is sufficient.

<rainbow spot>

The optical laminate of each example and each comparative example was overlaid on the surface of a display (manufactured by Sony Corporation, LCD TV model: KDL-46F5), and the optical laminate was visually observed from the front with the display displaying images. The following criteria were used to evaluate the degree of rainbow spots.

◎: No rainbow spots were observed.

○: Although slight rainbow spots were observed, they were sufficiently suppressed.

△: Rainbow spots were observed.

×: Rainbow spots are clearly observed.

<Moisture permeability (water vapor permeability)>

For the optical laminates of the examples and the comparative examples, the water vapor permeability in an environment with a temperature of 40° C. and a relative humidity of 90% RH was measured according to JIS-Z208. The measured water vapor permeability is 80g/m ² . In the case of day or less, it is determined that the water vapor barrier property is sufficient.

The materials and physical properties of the transparent substrates used in the optical laminates of Examples 1 to 7 and Comparative Examples 1 to 4 are also shown together with the haze, clarity of transmitted images, pencil hardness, degree of rainbow spots, and moisture permeability. Evaluation value.

The optical laminates of Examples 1 to 7 can sufficiently suppress rainbow spots to the extent that the visibility of the image is not impaired. In addition, it was confirmed that the optical laminate systems of Examples 1 to 7 were also excellent in water vapor barrier properties and surface hardness, and were excellent in durability.

On the other hand, the optical laminate of Comparative Example 1 uses a PET film with a retardation in the thickness direction of less than 3000 nm as a transparent substrate, so the surface hardness of the anti-glare layer is reduced.

The in-plane retardation of the optical laminate system PET film of Comparative Example 2 exceeds 600 nm, so rainbow spots cannot be sufficiently suppressed.

The optical layering system of Comparative Example 3 uses cellulose triacetate as a transparent substrate, and therefore has low water vapor barrier properties.

The optical laminate of Comparative Example 4 uses a PET film with a high retardation amount (the in-plane retardation amount and the retardation amount in the thickness direction is about 10,000 nm) as a transparent substrate. Therefore, although the rainbow spots are suppressed, compared with Examples 1 to 7, The transparent substrate becomes thicker. From this, it was confirmed that the optical laminate of Comparative Example 4 is not suitable for thinning.

In this way, it was confirmed that, according to the present invention, it is possible to provide an optical laminate having excellent durability, suppressed rainbow spots and high visibility, and achieving a thinner optical laminate.

The optical layered body of the present invention can be used as an anti-glare film for suppressing reflection of external light. In particular, it can be suitably used as an image display device as a base material of a polarizing plate and a protective film of the polarizing plate.

The present invention has been described in detail above, and the foregoing description is merely an illustration of the present invention in all points, and is not intended to limit the scope thereof. It is self-evident that various improvements and modifications can be made without departing from the scope of the present invention.

1‧‧‧ optical laminate

2‧‧‧Transparent substrate

3‧‧‧ Primer coating

4‧‧‧Anti-glare layer

Claims (7)

An optical layered body is provided with an undercoat layer on at least one surface of a transparent substrate containing polyethylene terephthalate with an in-plane retardation of 600 nm or less and a thickness direction retardation of 3000 nm or more. And the surface has an uneven shape anti-glare layer. The optical laminate according to claim 1, wherein the haze of the optical laminate is 0.5-50%. The optical laminate according to claim 1, wherein the anti-glare layer has a pencil hardness of 2H or more. The optical laminate according to claim 1, wherein the anti-glare layer includes one or more anti-glare layers containing a radiation-curable resin as a main component. The optical layered body according to claim 1, further comprising at least one layer among a refractive index adjustment layer, an antistatic layer, and an antifouling layer. A polarizing plate characterized by laminating a polarizing substrate on the transparent base material constituting the optical laminate according to any one of claims 1 to 5. A display device characterized by comprising the optical laminate according to any one of claims 1 to 5.

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