JP7121479B2 - Optical laminate, polarizing plate and display device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical laminate suitable for an antiglare film, and a polarizing plate and a display device using the same.

Optical laminates such as optical laminates, antireflection films, and antiglare films are used for display members such as liquid crystal display panels and touch panels. Cellulose ester films such as triacetyl cellulose, which are excellent in transparency and optical isotropy, have hitherto been widely used as transparent substrates constituting optical laminates. In particular, it has the drawback of insufficient moisture resistance and heat resistance. Therefore, various studies have been made to use a polyethylene terephthalate (PET) film as a transparent substrate in place of the cellulose ester film. A PET film has the advantage of being excellent in transparency, moisture resistance, heat resistance and mechanical strength, and being inexpensive.

However, since polyethylene terephthalate has an aromatic ring in its molecular structure, birefringence occurs in the plane of the PET film. Rainbow-like color unevenness (hereinafter referred to as "nijimura") occurs.

For example, Japanese Patent Laid-Open No. 2002-100001 discloses a technique for eliminating rainbow-like unevenness that occurs when PET is used as a transparent base material. In Patent Document 1, by using a polyester base material having an in-plane retardation (Re) of 3000 nm or more, the rainbow-like unevenness in the display device is improved.

Japanese Patent No. 5556926

In recent years, as display devices have become thinner and lighter, there has been a demand for thinner optical laminates, and attempts have been made to reduce the thickness of transparent substrates used in optical laminates. However, if the in-plane retardation of the PET film is increased as described in Patent Literature 1 in order to suppress rainbow-like irregularities that occur when the PET film is used, the thickness of the PET film inevitably increases. That is, when a PET film with high retardation is used as the transparent base material, it becomes difficult to reduce the thickness.

Therefore, an object of the present invention is to provide an optical laminate that is excellent in durability, suppresses iridescence, has high visibility, and can be made thinner, as well as a polarizing plate and a display device using the same. and

The optical laminate according to the present invention comprises a transparent substrate made of polyethylene terephthalate and having an in-plane retardation of 600 nm or less and a thickness direction retardation of 3000 nm or more. An antiglare layer is provided in this order, and the antiglare layer consists of a cured film of a composition containing an active energy ray-curable resin, resin particles, synthetic smectite, and alumina nanoparticles, and the thickness of the transparent base material is 12 to 40 μm, the thickness of the primer layer is 40 to 120 nm, the thickness of the antiglare layer is 1 to 20 μm, and the haze of the optical laminate is 23.2 to 44.3%.

A polarizing plate according to the present invention is characterized in that a polarizing substrate is laminated on a transparent substrate constituting the optical laminate.

Further, a display device according to the present invention is characterized by including the above-described optical layered body.

ADVANTAGE OF THE INVENTION According to this invention, the optical laminated body which is excellent in durability, and has high visibility by suppressing rainbow unevenness and an interference fringe, and which can be made thin, and a polarizing plate and a display apparatus using the same can be provided.

A cross-sectional view schematically showing an example of an optical layered body according to an embodiment. Sectional view schematically showing another example of the optical layered body according to the embodiment

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

The optical laminate 1 is obtained by laminating a primer layer 3 and an antiglare layer 4 on one surface of a transparent substrate 2 in this order.

(Transparent substrate)
The transparent base material 2 is a film that serves as the base of the optical laminate 1 . The thickness of the transparent substrate 2 is preferably 12-40 μm. When the thickness of the transparent base material 2 is less than 12 μm, the transparent base material 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 layered body 1 becomes thick, so that it cannot contribute to the thinning of the display member using the optical layered body 1 .

As the transparent substrate 2, a polyethylene terephthalate film (PET film) having an in-plane retardation (Re) of 600 nm or less and a thickness direction retardation (Rth) of 3000 nm or more is used. By using a PET film whose in-plane retardation and thickness direction retardation are within this range, it is possible to suppress rainbow-like unevenness when the optical layered body 1 is stacked on a polarizing plate or when a polarizer is provided on the optical layered body 1. Moreover, thinning of the transparent substrate 2 can be realized. If the in-plane retardation exceeds 600 nm, the thickness of the transparent substrate 2 becomes thicker than 40 μm, which is not preferable. Further, if the retardation in the thickness direction is less than 3000 nm, the hardness of the antiglare layer 4 when the optical layered body 1 is formed is lowered, which is not preferable. Although the upper limit of the retardation in the thickness direction of the transparent substrate 2 is not particularly limited, it is preferably 8000 nm or less.

In addition, since the PET film is excellent in low moisture permeability (water vapor barrier property), transparency, heat resistance and mechanical strength, the durability of the optical layered body 1 can be improved by using it as the transparent substrate 2 . Moreover, since the PET film is inexpensive, it is also advantageous in terms of manufacturing costs. Polyvinyl alcohol (PVA) film used in polarizing plates is highly hygroscopic, and when it absorbs moisture, it expands and changes its dimensions. is. Since the optical laminate 1 according to 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, the transparent substrate 2 may be subjected to a surface modification treatment in order to improve adhesion with the primer layer 3 and the antiglare layer 4 . Examples of surface modification treatment include alkali treatment, corona treatment, plasma treatment, sputtering treatment, application of surfactants, silane coupling agents, and the like, and Si vapor deposition.

(primer layer)
The primer layer 3 functions as an easy-adhesion layer that improves the adhesion of the antiglare layer 4 to the transparent substrate 2 . The primer layer 3 is formed, for example, by applying a primer layer-forming composition containing at least an active energy ray-curable resin to the surface of the transparent substrate 2 and curing the composition. The thickness of the primer layer 3 is preferably 40-120 nm.

(Antiglare layer)
The antiglare layer 4 is a layer that has fine irregularities on its surface and mainly imparts antiglare properties to the optical layered body 1 . The antiglare layer 4 can be formed, for example, by curing a composition for forming an antiglare layer containing an active energy ray-curable resin and fine particles on the surface of the primer layer 3 . The thickness of the antiglare layer 4 is preferably 1 to 20 μm. When the thickness of the antiglare layer 4 is less than 1 μm, the hardness of the antiglare layer 4 is insufficient. On the other hand, when the thickness of the antiglare layer 4 exceeds 20 μm, the thickness of the optical layered body 1 is too large to contribute to the thinning of the display member using the optical layered body 1 .

The active energy ray-curable resin used for the primer layer 3 and the antiglare layer 4 is a resin that is polymerized and cured by irradiation with active energy rays such as ionizing radiation and ultraviolet rays. The above (meth)acrylate monomers can be used. In this specification, "(meth)acrylate" is a generic term for both acrylate and methacrylate, and "(meth)acryloyl" is a generic term for both acryloyl and methacryloyl.

Resin materials that are cured by irradiation with ionizing radiation include radically polymerizable functional groups such as acryloyl groups, methacryloyl groups, acryloyloxy groups, and methacryloyloxy groups, and cationic polymerizable functional groups such as epoxy groups, vinyl ether groups, and oxetane groups. monomers, oligomers and prepolymers having Examples of monomers include methyl acrylate, methyl methacrylate, methoxypolyethylene methacrylate, cyclohexyl methacrylate, phenoxyethyl methacrylate, ethylene glycol dimethacrylate, dipentaerythritol hexaacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate. Oligomers and prepolymers include acrylate compounds such as polyester acrylates, polyurethane acrylates, polyfunctional urethane acrylates, epoxy acrylates, polyether acrylates, alkyd acrylates, melamine acrylates and silicone acrylates, unsaturated polyesters, tetramethylene glycol diglycidyl ethers, Epoxy compounds such as propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, bisphenol A diglycidyl ether and various alicyclic epoxies, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis{[(3- Examples include oxetane compounds such as ethyl-3-oxetanyl)methoxy]methyl}benzene and di[1-ethyl(3-oxetanyl)]methyl ether.

The above-described resin material can be cured by irradiation with ultraviolet light provided that a photopolymerization initiator is added. Photopolymerization initiators include radical polymerization initiators such as acetophenone, benzophenone, thioxanthone, benzoin, and benzoin methyl ether; cationic polymerization initiators such as aromatic diazonium salts, aromatic sulfonium salts, aromatic iodonium salts, and metallocene compounds. Agents can be used alone or in admixture.

The fine particles contained in the antiglare layer 4 are added to form a fine uneven structure on the surface to exhibit antiglare properties, and various inorganic fine particles and organic fine particles (fillers) can be used. However, the fine particles are not necessarily required, and the fine particles may be omitted as long as the surface of the antiglare layer 4 can be formed with fine irregularities necessary for developing the antiglare property.

When inorganic fine particles are used as the fine particles added to the antiglare layer 4, inorganic nanoparticles having an average particle size of 10 to 200 nm are preferable. 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. The swelling clay may be any material as long as it has a cation exchange ability and swells by taking in a solvent between the layers of the swelling clay. may It may also be a mixture of a natural product and a synthetic product. Examples of swelling clay include mica, synthetic mica, vermiculite, montmorillonite, ferrous montmorillonite, beidellite, saponite, hectorite, stevensite, nontronite, magadiite, ailarite, kanemite, layered titanate, smectite, synthetic smectite. etc. can be mentioned. These swelling clays may be used singly or in combination. In addition, colloidal silica, alumina, and zinc oxide may be used singly or in combination as inorganic fine particles. In addition to the swelling clay described above, one or more of colloidal silica, alumina and zinc oxide may be used in combination.

Layered organic clay is more preferable as the inorganic fine particles. In the present invention, the layered organic clay refers to a swelling clay in which an organic onium ion is introduced between layers. The organic onium ion is not limited as long as it can be organized by utilizing the cation exchange property of the swelling clay. As the inorganic fine particles, for example, synthetic smectite (layered organic clay mineral) can be used. The synthetic smectite functions as a thickening agent that increases the viscosity of the composition for forming an antiglare layer. Addition of synthetic smectite as a thickener suppresses sedimentation of resin particles and inorganic fine particles and contributes to the formation of an uneven structure on the surface of the antiglare layer.

When organic fine particles (filler) are used as fine particles added to the antiglare layer 4, acrylic resin, polystyrene resin, styrene-(meth)acrylic acid ester copolymer, polyethylene resin, epoxy resin, silicone resin, polyvinylidene fluoride, Resin particles made of a translucent resin material such as polyfluoroethylene resin can be used. In order to adjust the refractive index and the dispersion of the resin particles, two or more kinds of resin particles having different materials (refractive indexes) may be mixed and used. The resin particles (filler) aggregate in the base resin (binder resin) to form a fine uneven structure on the surface of the antiglare layer. By forming a random aggregation structure in the antiglare layer without blending the resin particles, it is possible to impart an uneven structure necessary for exhibiting the antiglare property. It becomes easy to adjust the size and number of uneven shapes on the surface of the antiglare layer.

In addition, a solvent may be appropriately added to the composition for forming the primer layer or the composition for forming the antiglare layer. Examples of solvents include dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane, tetrahydrofuran, anisole and phenetole, polyethylene glycol. ethers such as methyl ether; ketones such as acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone; and ethyl formate, propyl formate, n-formate. Examples include esters such as pentyl, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, n-pentyl acetate, and γ-butyrolactone, and cellosolves such as methyl cellosolve, cellosolve, butyl cellosolve, and cellosolve acetate. You may use these individually or in combination of 2 or more types.

In addition, to the composition for forming the primer layer or the composition for forming the antiglare layer, an antifouling agent, a surface preparation agent, a leveling agent, a refractive index adjustment agent, a photosensitizer, a conductive material, etc. are added as necessary. You can add medicine.

The optical layered body 1 according to the present embodiment is produced by applying a coating liquid of the above-described primer layer-forming composition to at least one surface of the transparent substrate 2 by a roll-to-roll method by a wet coating method. After curing the active energy ray-curable resin by irradiating it with an active energy ray such as an electron beam or ultraviolet rays, the coating liquid of the antiglare layer forming composition described above is applied onto the primer layer 3 by a wet coating method. Then, it can be formed by irradiating the coating film with an active energy ray such as an electron beam or an ultraviolet ray to cure the active energy ray-curable resin. Wet coating methods include flow coating method, spray coating method, roll coating method, gravure roll coating method, air doctor coating method, blade coating method, wire doctor coating method, knife coating method, reverse coating method, transfer roll coating method, Known methods such as microgravure coating, kiss coating, cast coating, slot orifice coating, calender coating and die coating can be employed. When the coating film is cured by ultraviolet irradiation, a high-pressure mercury lamp, halogen lamp, xenon lamp, fusion lamp, or the like can be used in the case of ultraviolet irradiation. The amount of ultraviolet irradiation is usually about 100 to 800 mJ/cm ² .

Since the optical layered body 1 according to the present embodiment uses a PET film as the transparent substrate 2, it has a lower moisture permeability and an excellent water vapor barrier property as compared with an acetylcellulose film such as triacetylcellulose. Moreover, since the PET film is excellent in heat resistance and mechanical strength, the durability of the optical laminate 1 can be improved by using it as the transparent substrate 2 . In addition, since PET film has high transparency and is inexpensive, it is suitable as an optical laminate used for image display devices and the like.

In general, when an optical laminate having a PET film as the transparent substrate 2 is used in an image display device, rainbow-like irregularities are likely to occur due to the birefringence of the PET itself. This rainbow unevenness is a factor that lowers the visibility of the image display device. However, in the optical layered body 1 according to the present embodiment, by using a PET film having an in-plane retardation of 600 nm or less and a thickness direction retardation of 3000 nm or more as the transparent substrate 2, the generation of rainbow spots can be suppressed. can be done. Interference fringes caused by a refractive index difference with the surface treatment layer 4 can be suppressed.

(Other modifications)
In the optical laminate 1 according to the above embodiment, at least one other functional layer 6 such as a refractive index adjusting layer, an antistatic layer, or an antifouling layer is provided on the antiglare layer 4 having an uneven surface. Also good.

FIG. 2 is a cross-sectional view showing an example of an optical laminate 1 in which a low refractive index layer is further provided as a functional layer 6 on the antiglare layer 4. As shown in FIG. The low refractive index layer is a refractive index adjustment layer for reducing the reflectance by lowering the refractive index of the surface. The low refractive index layer is formed by applying a coating liquid containing an ionizing radiation-curable material such as a polyester acrylate-based monomer, an epoxy acrylate-based monomer, a urethane acrylate-based monomer, or a polyol acrylate-based monomer and a polymerization initiator, and polymerizing the coating film. It can be cured and formed. In the low refractive index layer, low refractive particles include LiF, MgF, 3NaF.AlF or AlF (all of which have a refractive index of 1.4), or Na ₃ AlF ₆ (cryolite, refractive index of 1.33). You may disperse|distribute the low-refractive-index microparticles|fine-particles which consist of low refractive materials, such as. Also, as the low refractive index fine particles, particles having voids inside the particles can be preferably used. Particles having voids inside the particles can have the refractive index of air (≈1) in the void portions, so that the particles can be low refractive index particles with a very low refractive index. Specifically, the refractive index can be lowered by using low refractive index silica particles having voids inside.

The antistatic layer is coated with a coating liquid containing an ionizing radiation-curable material such as a polyester acrylate-based monomer, an epoxy acrylate-based monomer, a urethane acrylate-based monomer, or a polyol acrylate-based monomer, a polymerization initiator, and an antistatic agent. It can be formed by curing through polymerization. Examples of antistatic agents include metal oxide-based fine particles such as antimony-doped tin oxide (ATO) and tin-doped indium oxide (ITO), polymeric conductive compositions, quaternary ammonium salts, and the like. Available. The antistatic layer may be provided on the outermost surface of the optical laminate, or may be provided between the antiglare layer and the translucent substrate.

The antifouling layer is provided on the outermost surface of the optical layered body, and enhances the antifouling property by imparting water repellency and/or oil repellency to the optical layered body. The antifouling layer can be formed by dry coating or wet coating silicon oxide, fluorine-containing silane compound, fluoroalkylsilazane, fluoroalkylsilane, fluorine-containing silicon compound, perfluoropolyether group-containing silane coupling agent, or the like. .

Instead of the above-described low refractive index layer, antistatic layer, antifouling layer, or in addition to the low refractive index layer, antistatic layer, antifouling layer, at least an infrared absorbing layer, an ultraviolet absorbing layer, a color correction layer, etc. One layer may be provided.

Moreover, in the optical layered body 1 according to the present embodiment, it is preferable that the antiglare layer 4 has a random aggregation structure.

The random aggregation structure is a three-dimensionally complicated first phase containing a relatively large amount of resin components (binder components) and a second phase containing a relatively large amount of inorganic components. It refers to a structure in which two phases are unevenly distributed around fine particles (resin particles). By forming a random aggregation structure in the antiglare layer 4, fine unevenness can be reduced, so that antiglare properties and blackness during black display can be improved. A random aggregate structure can be formed, for example, by the method described in Japanese Patent No. 5802043.

Further, even when a random aggregate structure is formed in the antiglare layer 4, the above-described low refractive index layer, antistatic layer, antifouling layer, infrared absorption layer, ultraviolet absorption layer, color At least one functional layer 6 such as a correction layer may be provided.

A polarizing plate may be configured using the optical layered body 1 according to the present embodiment. Specifically, a polarizing film is formed by adsorbing and orienting iodine or a dye on a PVA film, and a polarizing plate is formed by laminating the optical layered body 1 according to the present embodiment as a protective film on both sides of the polarizing film. Configurable. Alternatively, a polarizing plate is constructed by providing a polarizing layer by a known method on the other surface of the transparent substrate 2 (the surface on which the antiglare layer 4 is not provided) of the optical laminate 1 shown in FIG. Also good. In this case, the optical layered body 1 or another protective film may be laminated on the polarizing layer. The polarizing layer can be formed, for example, by adsorbing and orienting iodine or a dye on a PVA film.

Further, the optical layered body 1 according to this embodiment can be used in combination with a liquid crystal panel or the like to configure a display device. As an example of the configuration of the display device, there is a structure in which the optical layered body 1 according to the present embodiment, a polarizing plate, a liquid crystal panel, a polarizing plate, and a backlight unit are laminated in this order from the viewing side. Further, a touch sensor can be laminated to configure a display device with a touch sensor.

Further, the optical layered body 1 according to the present embodiment can be used as an optical layered body used for display devices such as smartphones, tablet computers, and notebook computers, and display devices with a touch sensor (touch panels). Examples of the optical layered body include the above-mentioned polarizing plate, antireflection film, antiglare property, etc., in addition to the optical layered body. Specifically, the optical laminate 1 according to 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 as a film provided on the outermost surface of an on-cell or in-cell touch panel. Alternatively, it can be used as an intermediate film provided between a touch sensor and a display panel in a touch panel assembled by a direct bonding method or an air gap method.

Further, in the present embodiment, an example in which the primer layer 3 and the antiglare layer 4 are provided on one side of the transparent base material 2 has been described, but the primer layer 3 and the antiglare layer 4 are provided on both sides of the transparent base material 2. An optical laminate may be constructed.

EXAMPLES Examples in which the present invention is specifically carried out will be described below. In the following examples and comparative examples, optical laminates were produced by providing a primer layer and an antiglare layer on a transparent base material, but the optical laminate according to the present invention was made only of this three-layer film. It is not limited.

<Composition for Primer Layer Formation>
A composition for forming a primer layer was prepared by mixing the following materials.
・Base resin Product name: UF8001G (non-yellowing type oligourethane acrylate), Kyoeisha Chemical Co., Ltd. 0.85 parts by mass ・Polymerization initiator Product name: Irgacure (registered trademark) 184 (1-hydroxycyclohexylphenyl ketone), BASF 0.04 parts by mass Solvent Methyl ethyl ketone (MEK) 17.46 parts by mass Polyethylene glycol monomethyl ether (PGME) 11.64 parts by mass

<Composition for Forming Antiglare Layer>
Antiglare layer-forming compositions 1 to 4 were prepared by mixing the following materials.

[ Composition 1 for forming antiglare 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 Resin particles (filler): polystyrene particles, average particle size 2.0 μm, refractive index 1.595
1.0 parts by mass Inorganic fine particles 1: Synthetic smectite 0.5 parts by mass Inorganic fine particles 2: Alumina nanoparticles, average particle size 40 nm 2.0 parts by mass Photopolymerization initiator: Irgacure 184 (manufactured by BASF Japan) 4. 8 parts by mass As a solvent, a mixed solvent in which toluene and isopropyl alcohol were mixed at a ratio of 16:37 was used.

[ Composition 2 for forming antiglare 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 Resin particles (filler): styrene-methyl methacrylate copolymer particles, average particle size 2.0 μm, refractive index 1.515
1.0 parts by mass Inorganic fine particles 1: Synthetic smectite 0.5 parts by mass Inorganic fine particles 2: Alumina nanoparticles, average particle size 40 nm 2.0 parts by mass Photopolymerization initiator: Irgacure 184 (manufactured by BASF Japan) 4. 8 parts by mass As a solvent, a mixed solvent in which toluene and isopropyl alcohol were mixed at a ratio of 16:37 was used.

[ Composition 3 for forming antiglare layer]
・ Base resin: UV / EB curable resin Light acrylate PE-3A (pentaerythritol triacrylate, manufactured by Kyoeisha Chemical Co., Ltd.), refractive index 1.52
82.4 parts by mass Resin particles (filler): styrene-methyl methacrylate copolymer particles, average particle size 3.35 μm, refractive index 1.565
10.0 parts by mass Inorganic fine particles 1: Synthetic smectite 1.8 parts by mass Inorganic fine particles 2: Alumina nanoparticles, average particle size 40 nm 1.0 parts by mass Photopolymerization initiator: Irgacure 184 (manufactured by BASF Japan) 4. 8 parts by mass Toluene was used as the solvent.

[Antiglare layer-forming composition 4]
・ Base resin: UV / EB curable resin Light acrylate PE-3A (pentaerythritol triacrylate, manufactured by Kyoeisha Chemical Co., Ltd.), refractive index 1.52
82.4 parts by mass Resin particles (filler): polystyrene particles, average particle size 3.5 μm, refractive index 1.595
10.0 parts by mass Inorganic fine particles 1: Synthetic smectite 1.8 parts by mass Inorganic fine particles 2: Alumina nanoparticles, average particle size 40 nm 1.0 parts by mass Photopolymerization initiator: Irgacure 184 (manufactured by BASF Japan) 4. 8 parts by mass Toluene was used as the solvent.

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

<Preparation of optical laminate>
(Examples 1 to 4, Comparative Examples 1, 2 and 4)
A coating solution of the primer layer-forming composition described above is applied to one surface of a transparent substrate by a bar coating method, dried, and then irradiated with ultraviolet rays at an irradiation dose of 200 mJ/m ² using a metal halide lamp to form a coating film. was cured to form a primer layer. The coating amount of the coating solution of the primer layer-forming composition was adjusted so that the thickness of the cured film was 40 nm.

Next, on the formed primer layer, the coating liquid of the antiglare layer forming composition 1 is applied by a bar coating method and dried, and then irradiated with ultraviolet rays at an irradiation dose of 200 mJ / m ² using a metal halide lamp. Then, the coating film was cured to form an antiglare layer. The coating amount of the antiglare layer-forming composition 1 was adjusted so that the thickness of the cured film would be the value shown in Table 1.

(Example 5)
An optical laminate was produced in the same manner as in Example 1, except that Antiglare layer-forming composition 2 was used instead of Antiglare layer-forming composition 1 in Example 1.

(Example 6)
An optical layered body was produced in the same manner as in Example 1, except that Antiglare layer-forming composition 3 was used instead of Antiglare layer-forming composition 1 in Example 1.

(Example 7)
An optical layered body was produced in the same manner as in Example 1, except that Antiglare layer-forming composition 4 was used instead of Antiglare layer-forming composition 1 in Example 1.

(Comparative Example 3)
On one side of the transparent substrate, without forming a primer layer, the coating liquid of the antiglare layer-forming composition 1 was applied by a bar coating method, dried, and then irradiated with a metal halide lamp at a dose of 200 mJ/. The coating film was cured by irradiating ultraviolet rays at m ² to form an antiglare layer. The coating amount of the coating liquid of the antiglare layer-forming composition was adjusted so that the thickness of the cured film would be the value shown in Table 1.

The optical layered bodies obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were evaluated for haze, transmitted image definition, pencil hardness, degree of iridescence, and moisture permeability. The evaluation method and evaluation criteria are as follows.

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

<Clearness of transmitted image>
The transmission image definition was measured according to JIS K7105 using an image clarity measuring instrument (ICM-1T, manufactured by Suga Test Instruments Co., Ltd.) with an optical comb width of 0.5 mm.

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

<Nijimura>
The optical layered body according to each example name and each comparative example is superimposed on the surface of a display (manufactured by Sony Corporation, liquid crystal television model number: KDL-46F5), and an image is displayed on the display, and the optical layered body is viewed from the front. , and the degree of rainbow spots was evaluated according to the following criteria.
A: Rainbow spots are not observed.
◯: Rainbow spots are slightly observed, but are sufficiently suppressed.
Δ: Nijimura is observed.
x: Rainbow spots are conspicuously observed.

<Moisture Permeability (Water Vapor Permeability)>
For the optical layered bodies according to each example and each comparative example, the water vapor permeability was measured in accordance with JIS-Z208 in an environment of a temperature of 40° C. and a relative humidity of 90% RH. When the measured water vapor permeability was 80 g/m ² ·day or less, it was determined that the water vapor barrier property was 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, as well as evaluation values of haze, transmitted image definition, pencil hardness, degree of iridescence, and moisture permeability were evaluated. Also shown.

In the optical laminates according to Examples 1 to 7, rainbow unevenness was sufficiently suppressed to the extent that visibility of images was not impaired. Further, it was confirmed that the optical layered bodies according to Examples 1 to 7 were excellent in water vapor barrier property and surface hardness, and excellent in durability.

On the other hand, in the optical layered body according to Comparative Example 1, the surface hardness of the antiglare layer was lowered because the PET film having a retardation in the thickness direction of less than 3000 nm was used as the transparent substrate.

In the optical layered body according to Comparative Example 2, since the in-plane retardation of the PET film exceeded 600 nm, rainbow-like unevenness could not be sufficiently suppressed.

The optical layered body according to Comparative Example 3 had low water vapor barrier properties because triacetyl cellulose was used for the transparent substrate.

In the optical laminate according to Comparative Example 4, a PET film with high retardation (in-plane retardation and thickness direction retardation of about 10000 nm) was used as the transparent base material, so that rainbows were suppressed, but compared to Examples 1 to 7. The thickness of the transparent substrate is increased. Therefore, it was confirmed that the optical layered body according to Comparative Example 2 is not suitable for thinning.

As described above, it was confirmed that the present invention can provide an optical laminate that is excellent in durability, suppresses rainbow unevenness, has high visibility, and can be made thinner.

The optical laminate according to the present invention can be used as an antiglare film that suppresses reflection of external light, and can be suitably used in image display devices as a base material for polarizing plates or as a protective film for polarizing plates.

REFERENCE SIGNS LIST 1 optical laminate 2 transparent substrate 3 primer layer 4 antiglare layer 6 functional layer

Claims (6)

A transparent substrate made of polyethylene terephthalate and having an in-plane retardation of 600 nm or less and a thickness direction retardation of 3000 nm or more is provided with a primer layer and an antiglare layer having an uneven surface in this order on at least one surface,
wherein the antiglare layer is a cured film of a composition containing an active energy ray-curable resin, resin particles, synthetic smectite, and alumina nanoparticles;
The transparent base material has a thickness of 12 to 40 μm,
The primer layer has a thickness of 40 to 120 nm,
The antiglare layer has a thickness of 1 to 20 μm,
An optical laminate having a haze of 23.2 to 44.3%. 2. The optical laminate according to claim 1, wherein the antiglare layer has a pencil hardness of 2H or more. 3. The optical laminate according to claim 1, wherein the antiglare layer comprises one or more antiglare layers containing a radiation-curable resin as a main component. 4. The optical laminate according to any one of claims 1 to 3, further comprising at least one layer selected from a refractive index adjusting layer, an antistatic layer and an antifouling layer. A polarizing plate comprising a polarizing substrate laminated on the transparent substrate constituting the optical laminate according to any one of claims 1 to 4. A display device comprising the optical laminate according to any one of claims 1 to 4.

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