TWI650234B - Optical laminate, polarizing plate and display device - Google Patents

Abstract

The present invention provides an optical laminate that can maintain anti-glare property and contrast and suppress flicker even when applied to a high-definition image display panel. The optical layered body of the present invention is an optical layered body formed by laminating at least one or more optical functional layers on a light-transmitting substrate, and is characterized in that an uneven shape is formed on at least one surface of the optical functional layer ; The optical functional layer having the uneven shape contains at least a resin component, two kinds of inorganic fine particles and resin particles; the optical laminate has an internal haze X and a total haze Y satisfying the following conditional expressions (1) to (4): Y>X. . . (1)

Y≦X+17. . . (2)

Y≦57. . . (3)

19≦X≦40. . . (4)

The sharpness of the penetrating image using an optical comb with a width of 0.5mm is 10 to 50%; when the surface roughness shape of the outermost surface of the optical functional layer is measured by optical interference, the area of the portion with a roughness height of 0.4 μm or more is determined Less than 3.5% of the area.

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.

The anti-glare film uses an uneven structure on the surface to scatter external light, thereby exerting anti-glare properties. The uneven structure on the surface of the anti-glare film is formed by agglomerating particles in the resin layer on the outermost surface.

In addition to anti-glare properties, anti-glare films also require functions such as anti-sparkling property and high contrast. In the past, by adjusting the shape, particle size, refractive index, coating properties (viscosity), coating process, etc. of particles (fillers), the uneven structure of the surface (external scattering) and internal scattering were optimized and further improved. Anti-glare, flicker resistance, high contrast. However, there is a trade-off relationship between anti-glare, flicker resistance and high contrast.

By using a filler with a large particle size, increasing the amount of filler added, and enhancing the aggregation of the filler, the anti-glare property is improved. In this case, although the number of irregularities is increased and the size of the irregularities is increased, the anti-glare property can be improved, but due to the increase of the lens effect, the flicker resistance is deteriorated.

Although the internal scattering is increased by using a filler with a large refractive index difference from the resin or increasing the amount of filler added, the flicker resistance is improved , But the contrast will decrease due to the increase in diffused light. In addition, although the surface irregularities are made finer, that is, the average length Sm of the irregularities is reduced, the flicker resistance can also be improved, but it becomes a low-quality anti-glare property in which the white tone is conspicuous.

By reducing the internal scattering, although the contrast can be improved, the scintillation resistance will be deteriorated. In addition, although the low-reflection layer must be provided to improve the contrast, it will become a multi-layer structure and become disadvantageous in terms of cost.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 10-20103

Due to the high definition of liquid crystal panels in recent years, when the conventional anti-glare film maintains anti-glare properties and contrast as before, flicker may occur. On the other hand, in order to improve the flicker resistance, it is necessary to sacrifice anti-glare and contrast.

Therefore, an object of the present invention is to provide an optical laminate that can maintain flare resistance and contrast while suppressing flicker while being applied to an image display panel, particularly a high-definition image display panel of 200ppi or more, and use the same Polarizer and image display device.

The present invention relates to an optical laminate formed by laminating at least one or more optical functional layers on a translucent substrate. A concave-convex shape is formed on at least one surface of the optical functional layer, and the optical functional layer having a concave-convex shape contains at least a resin component, two kinds of inorganic fine particles, and resin particles The optical laminate has an internal haze X and a total haze Y satisfying the following conditional expressions (1) to (4): Y>X. . . (1)

Y≦X+17. . . (2)

Y≦57. . . (3)

19≦X≦40. . . (4)

When the sharpness of the penetrating image of the optical comb with a width of 0.5 mm is 10 to 50%, and the surface roughness shape of the outermost surface of the optical functional layer is measured by the optical interference method, the area of the portion with a roughness height of 0.4 μm or more is determined Less than 3.5% of the area.

According to the present invention, an optical laminate capable of maintaining anti-glare properties and contrast while suppressing flicker even when applied to a high-definition image display panel of 200ppi or more, and a polarizing plate and image display using the same Device.

1‧‧‧Translucent substrate

2‧‧‧Optical function layer

3. 5, 6, 8 ‧‧‧ transparent substrate

4, 7‧‧‧ Polarized layer

11, 12‧‧‧ Polarizer

13‧‧‧ LCD cell

14‧‧‧Backlight unit

100‧‧‧Optical laminate

110‧‧‧ Polarizer

120‧‧‧Display device

FIG. 1 is a graph plotting the relationship between the amount of resin particles (organic filler) described in Table 1 and the internal haze of the obtained optical laminate.

FIG. 2 is a graph plotting the addition amount of resin particles and the addition amount of colloidal silica in Examples 1 to 12 and Comparative Examples 1 to 17 shown in Table 2. FIG.

FIG. 3 is a diagram showing the irregularities on the surface of the optical functional layer of the optical laminate in Example 2. FIG.

FIG. 4 is a diagram showing the uneven shape of the optical functional layer surface of the optical laminate of Comparative Example 6. FIG.

FIG. 5 is a graph showing the area ratio distribution of the height of the unevenness on the surface of the optical functional layer of Example 2 and Comparative Example 6. FIG.

Figure 6 is an enlarged view within the dotted frame shown in Figure 5.

FIG. 7 is a cross-sectional STEM image of the optical functional layer of the optical laminate of Example 2. FIG.

FIG. 8 is a cross-sectional STEM image of the optical functional layer of the optical laminate of Comparative Example 6. FIG.

Fig. 9 is a cross-sectional view showing a schematic configuration of an optical laminate in the embodiment.

Fig. 10 is a cross-sectional view showing a schematic configuration of the polarizing plate of the embodiment.

Fig. 11 is a cross-sectional view showing a schematic configuration of the display device of the embodiment.

[Forms for carrying out the invention]

Fig. 9 is a cross-sectional view showing a schematic configuration of an optical laminate in the embodiment. The optical laminate 100 of the embodiment includes a translucent base 1 and at least one optical functional layer 2 laminated on the translucent base 1. Fine irregularities are formed on the surface of the optical functional layer 2. The unevenness scatters external light, so that the optical functional layer 2 can exert anti-glare properties.

As the light-transmitting substrate, polyethylene terephthalate (PET), triacetyl cellulose (TAC), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA) can be suitably used , Polycarbonate (PC), poly Acetylene imine (PI), polyethylene (PE), polypropylene (PP), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), cyclic olefin copolymer (COC), norbornene-containing resin, polyether ash , Cellophane, aromatic polyamide and other resin films.

The total light transmittance (JIS K7105) of the translucent substrate is preferably 80% or more, and more preferably 90% or more. In addition, considering the productivity and handleability of the optical laminate, the thickness of the light-transmitting substrate is preferably 1 to 700 μm, and more preferably 25 to 250 μm.

In order to improve the adhesion with the optical functional layer, it is preferable to perform surface modification treatment on the translucent base. Examples of the surface modification treatment include alkali treatment, corona treatment, plasma treatment, machine treatment, coating of surfactants or silane coupling agents, and silicon vapor deposition.

The optical functional layer contains base resin, resin particles (organic filler), and two kinds of inorganic fine particles. The optical functional layer is formed by applying a resin composition mixed with a base resin, resin particles, and two types of inorganic fine particles to a light-transmitting substrate and hardening the coating film. The base resin is irradiated with free radiation or Hardened by ultraviolet light.

Hereinafter, the constituent components of the resin composition for forming the optical functional layer will be described.

As the base resin, a resin hardened by irradiating free radiation or ultraviolet rays can be used.

As a resin material that is hardened by irradiating free radiation, a radically polymerizable functional group having an acryl group, a methacryl group, acryl group, a methacryl group, or epoxy can be used alone or in combination. Monomers, oligomers, and prepolymers of cationic polymerizable functional groups such as alkyl groups, vinyl ether groups, and oxetane groups. As a monomer, Exemplary: methyl acrylate, methyl methacrylate, methoxy polyethyl methacrylate, cyclohexyl methacrylate, phenoxy ethyl methacrylate, ethylene glycol dimethacrylate, Dipentaerythritol hexaacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, etc. Examples of oligomers and prepolymers include polyester acrylate, polyurethane acrylate, multifunctional urethane acrylate, epoxy acrylate, polyether acrylate, and alkyd acrylate. (alkyd acrylate), melamine acrylate, silicone acrylate and other acrylate compounds; unsaturated polyester, butylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, bisphenol A Epoxy compounds such as diglycidyl ether or various alicyclic epoxy; 3-ethyl-3-hydroxymethyloxetane, 1,4-bis{[(3-ethyl-3- Oxetane compounds such as oxetane) methoxy] methyl} benzene, di[1-ethyl(3-oxetanyl)] methyl ether and the like.

The above-mentioned resin material can be hardened by irradiation of ultraviolet rays on condition that the photopolymerization initiator is added. As a photopolymerization initiator, acetophenone series, benzophenone series, 9-oxysulfide can be used alone or in combination System, benzoin, benzoin methyl ether and other free-radical polymerization initiators; aromatic diazonium salts, aromatic cerium salts, aromatic iodonium salts, metallocene catalyst compounds and other cationic polymerization initiators.

The resin particles (organic filler) added to the optical functional layer aggregate in the base resin to form a fine uneven structure on the surface of the optical functional layer. As the resin particles, acrylic resin, polystyrene resin, styrene-acrylic copolymer, polyethylene resin, epoxy resin, silicone resin, polyvinylidene fluoride, polyvinylidene fluoride resin, etc. can be used Translucent resin material. The refractive index of the resin particle material is preferably 1.40 to 1.75.

The refractive index n _{f of the} resin particles and the refractive index n _{z of the} base resin preferably satisfy the following condition (α), and more preferably satisfy the following condition (β).

|n _z -n _f |≧0.025. . . (α)

|n _z -n _f |≧0.035. . . (β)

When the refractive index n _z of the resin material as the base material and the refractive index n _{f of the} resin particles do not satisfy the condition (α), in order to obtain the expected internal haze, it is necessary to increase the amount of the resin particles added, and the image sharpness will change difference.

The average particle diameter of the resin particles is preferably 0.3 to 10.0 μm, and more preferably 1.0 to 7.0 μm. When the average particle diameter of the resin particles is less than 0.3 μm, the anti-glare property decreases. On the other hand, if the average particle diameter of the resin particles exceeds 10.0 μm, the area ratio of the height of the irregularities on the surface of the optical functional layer cannot be controlled, and the scintillation resistance deteriorates.

The first inorganic fine particles and the second inorganic fine particles are added to the base resin of the optical functional layer as two types of inorganic fine particles.

As the first inorganic fine particles, colloidal silica, alumina, and zinc oxide can be used alone or in combination. By adding the first inorganic fine particles, the excessive aggregation of the resin particles can be suppressed, and the uneven structure formed on the surface of the optical functional layer can be made uniform, that is, the local unevenness can be suppressed from increasing. By adding the first inorganic fine particles, the anti-glare property and high contrast can be maintained while improving the flicker resistance.

The first inorganic fine particles are preferably inorganic nanoparticles having an average particle diameter of 10 to 100 nm. Using colloidal silica as the first inorganic fine particles In this case, the average particle diameter is more preferably about 20 nm, and when alumina or zinc oxide is used as the first inorganic fine particles, the average particle diameter is more preferably about 40 nm. The added amount of the first inorganic fine particles is preferably 0.05 to 10%, and more preferably 0.1 to 5.0% with respect to the total weight of the resin composition for forming an optical functional layer. If the added amount of the first inorganic fine particles is out of this range, the area ratio of the height of the irregularities on the surface of the optical functional layer cannot be controlled, and the scintillation resistance deteriorates.

The second inorganic fine particles are preferably inorganic nanoparticles having an average particle diameter of 10 to 200 nm. The added amount of the second inorganic fine particles is preferably 0.1 to 5.0%. As the second inorganic fine particles, swelling clay can be used. As long as the swelling clay has a cation exchange capability, a solvent is injected into the layers of the swelling clay to swell, and it may be natural or synthetic (including substitutions and derivatives). Also, it may be a mixture of natural products and synthetic products. Examples of the bentonite clay include mica, synthetic mica, vermiculite, microcrystalline kaolinite, iron microcrystalline kaolinite, aluminum bentonite, magnesium bentonite, lithium bentonite, magnesia saponite, iron bentonite, and maltol Sodalite, ilerite, bernesite, layered titanate, bentonite, synthetic bentonite, etc. These swelling clays can be used alone or in combination.

As the second inorganic fine particles, layered organic clay is more preferable. In the present invention, the layered organic clay refers to a layer in which organic onium ions are introduced into the swellable clay. The organic onium ion is not particularly limited as long as it can be organicized using the cation exchangeability of the swelling clay. As the second inorganic fine particles, for example, synthetic bentonite (layered organic clay mineral) can be used. Synthetic bentonite functions as a tackifier that increases the viscosity of the resin composition for forming an optical function layer. Add synthetic bentonite as a thickener to suppress the precipitation of resin particles and first inorganic fine particles , And contributes to the formation of the uneven structure on the surface of the optical function layer.

In addition, when the first inorganic fine particles and the second inorganic fine particles are used in combination, the first inorganic fine particles and the second inorganic fine particles form an aggregate in the optical functional layer. The aggregate suppresses the aggregation of the resin particles, and flattens the unevenness of the concave-convex shape on the surface of the optical functional layer, thereby making the scattering of light on the surface of the optical functional layer uniform and improving the scintillation resistance.

Moreover, a leveling agent may be added to the resin composition for optical function layer formation. The leveling agent has the surface of the coating film aligned to the drying process, which makes the surface tension of the coating film uniform, so as to reduce the function of surface defects of the coating film.

In addition, an organic solvent may be appropriately added to the resin composition for forming an optical functional layer. Examples of organic solvents include alcohol-based, ester-based, ketone-based, ether-based, and aromatic hydrocarbons.

The film thickness of the optical function layer is preferably 1.0 to 12.0 μm, and more preferably 3.0 to 10.0 μm. When the film thickness of the optical functional layer is less than 1 μm, the curing failure may occur due to the inhibition of oxygen, and the scratch resistance of the optical functional layer is likely to be reduced. On the other hand, if the film thickness of the optical function layer exceeds 12.0 μm, curl due to curing shrinkage of the base resin layer becomes large, which is not good.

In addition, the thickness of the optical function layer is preferably 110 to 300% of the average particle diameter of the resin particles, and more preferably 120 to 250%. When the film thickness of the optical functional layer is less than 110% of the average particle diameter of the resin particles, it becomes a low-quality anti-glare property in which the white tone is conspicuous. On the other hand, if the film thickness of the optical function layer exceeds 300% of the average particle diameter of the resin particles, the anti-glare property is insufficient, which is not good.

In addition, in the optical layered body of this embodiment, the internal haze X and the total haze Y simultaneously satisfy the following conditions (1) to (4).

Y>X. . . (1)

Y≦X+17. . . (2)

Y≦57. . . (3)

19≦X≦40. . . (4)

When the internal haze X does not satisfy the conditional expression (4) and is less than 19%, the flicker resistance is insufficient. On the other hand, when the internal haze X does not satisfy the conditional expression (4) and exceeds 40%, the contrast deteriorates.

The internal haze X preferably satisfies the following conditional expression (4)'. When the internal haze X satisfies the conditional expression (4)', the flicker resistance and contrast can be improved both ways.

25≦X≦35. . . (4)’

In addition, when the total haze Y does not satisfy the conditional expression (3) and exceeds 57%, the unevenness of the surface of the optical functional layer is large, and the flicker resistance is insufficient.

The sharpness of the penetrating image of the optical layered body of the present embodiment is preferably 10 to 50%, and more preferably 15 to 45%, measured using an optical comb with a width of 0.5 mm. When the sharpness of the penetration image is less than 10%, the flicker resistance becomes poor. On the other hand, if the sharpness of the penetration image exceeds 50%, the anti-glare property deteriorates.

When the unevenness shape of the surface of the optical functional layer of the present embodiment is measured by the optical interference method, the area of the portion where the unevenness height is 0.4 μm or more is 3.5% or less. If the surface of the concave-convex structure of the optical functional layer has a concave-convex height of 0.4 μm or more and the area exceeds 3.5%, a large number of local concave-convex parts will be distributed in large amounts. In the case of an anti-glare film of an image display device of 200 ppi or more, the flicker resistance deteriorates.

In the past, in order to suppress the aggregation of excess fillers, methods of adjusting the viscosity of the coating, methods of increasing the solid content of the coating at the time of coating, and methods of using a solvent with a fast volatilization rate to suppress convection during drying were used. In this case, there is a problem that a planar failure such as uneven coating is likely to occur. On the other hand, as described in the above embodiment, if the method of adding two kinds of inorganic fine particles does not affect the coating physical properties or the drying speed, the coating suitability can be maintained and the flicker resistance can be improved.

Fig. 10 is a cross-sectional view showing a schematic configuration of the polarizing plate of the embodiment. The polarizing plate 110 includes an optical laminate 100 and a polarizing film 11. As shown in FIG. 9, the optical layered body 100 is provided with a polarizing film (polarizing base) 11 on the surface of the translucent base 1 where the optical functional layer 2 is not provided. The polarizing film 11 is formed by sequentially laminating a transparent substrate 3, a polarizing layer 4 and a transparent substrate 5. The materials of the transparent substrates 3 and 5 and the polarizing layer 4 are not particularly limited. Generally, the materials used for the polarizing film can be appropriately used.

Fig. 11 is a cross-sectional view showing a schematic configuration of the display device of the embodiment. The display device 120 is a device for sequentially laminating the optical laminate 100, the polarizing film 11, the liquid crystal cell 13, the polarizing film (polarizing substrate) 12, and the backlight unit 14. The polarizing film 12 is a thin film in which a transparent substrate 6, a polarizing layer 7 and a transparent substrate 8 are laminated in this order. The materials of the transparent substrates 6 and 8 and the polarizing layer 7 are not particularly limited, and generally the materials used for the polarizing film can be appropriately used. The liquid crystal cell 13 includes a liquid crystal panel in which liquid crystal molecules are sealed between a pair of transparent substrates with transparent electrodes, and a color filter, which is A device that changes the alignment of liquid crystal molecules in response to a voltage applied between transparent electrodes, thereby controlling the light transmittance of each image number to form an image. The backlight unit 14 includes a light source and a light diffusion plate (neither is shown), which is a lighting device that diffuses light emitted from the light source uniformly and then exits from the exit surface.

In addition, the display device 120 shown in FIG. 11 may further include a diffusion film, a thin film, a brightness enhancement film, a phase difference film for compensating the phase difference between the liquid crystal cell and the polarizing plate, and a touch sensor.

The optical layered body of the present embodiment may include at least one of a refractive index adjustment layer such as a low refractive index layer, an antistatic layer, and an antifouling layer in addition to the optical functional layer that suppresses flicker.

The low-refractive-index layer is provided on the optical functional layer that controls scintillation, and it is a functional layer for reducing the reflectivity by reducing the refractive index of the surface. Low refractive index layer, can be coated with free radiation curable materials including polyester acrylate monomers, epoxy acrylate monomers, urethane acrylate monomers, polyol acrylate monomers and polymerization The coating liquid of the initiator is formed by curing the coating film by polymerization. Low-refractive-index microparticles containing low-refractive materials such as LiF, MgF, 3NaF‧AlF or AlF (refractive index are all 1.4), or Na ₃ AlF ₆ (cryolite, refractive index 1.33) can be dispersed as low-refractive particles in low-refractive particles Refractive index layer. In addition, particles having voids inside the particles can be suitably used as the low-refractive-index fine particles. For particles with voids inside the particles, the void part can be used as the refractive index of air (≒1), so low-refractive-index particles with very low refractive index can be formed. Specifically, the refractive index can be reduced by using low-refractive-index silica particles with voids inside.

The antistatic layer can be Monomers, epoxy acrylate monomers, urethane acrylate monomers, polyol acrylate monomers, and other free radiation hardening materials, polymerization initiators, and antistatic agents It is formed by hardening through polymerization. As the antistatic agent, for example, metal oxide-based fine particles such as antimony-doped tin oxide (ATO), tin-doped indium oxide (ITO), or the like, a polymer conductive composition, or a quaternary ammonium salt can be used. The antistatic layer may be provided on the outermost surface of the optical layered body, or between the optical functional layer for controlling flicker and the translucent substrate.

The antifouling layer is provided on the outermost surface of the optical layered body and improves the antifouling property by imparting water repellency and/or oil repellency to the optical layered body. The anti-fouling layer can be carried out by applying silicon oxide, fluorine-containing silane compound, fluoroalkyl silazane, fluoroalkyl silazane, fluorine-containing silicon-based compound, silane coupling agent containing perfluoropolyether group, etc. It is formed by dry coating or wet coating.

In addition to the above low refractive index layer, antistatic layer, antifouling layer, or after the low refractive index layer, antistatic layer, antifouling layer is provided, at least one infrared absorption layer, ultraviolet absorption layer, color Correction layer, etc.

[Example]

Hereinafter, examples of the optical laminate according to the embodiment will be described.

(Manufacturing method of optical laminate)

As a light-transmitting substrate, a triacetyl cellulose film with a thickness of 40 μm was used. After coating the following coating liquid for forming an optical functional layer on a light-transmitting substrate and drying it (solvent volatilization), the coating film is cured by polymerization, This forms an optical function layer.

[Coating Liquid for Forming Optical Functional Layer]

‧Base resin: UV/EB curable resin Light Acrylate PE-3A (pentaerythritol triacrylate, manufactured by Kyoeisha Chemical Co., Ltd.), refractive index 1.52

‧Resin filler:

<Examples 1 to 10, Comparative Examples 1 to 17>

Cross-linked styrene monodisperse particles SX350H (manufactured by Soken Chemical Co., Ltd.) Average particle diameter 3.5 μm, refractive index 1.595

<Example 11>

Styrene monodisperse filler SSX302ABE (manufactured by Sekisui Chemical Products Co., Ltd.) average particle diameter 2.0 μm, refractive index 1.595

<Example 12>

Cross-linked styrene monodisperse particles SX500H (manufactured by Soken Chemical Co., Ltd.) Average particle diameter 5.0 μm, refractive index 1.595

‧Colloidal silica: ORGANOSILICA SOL MEK-ST (manufactured by Nissan Chemical Industry Co., Ltd.)

‧Synthetic bentonite: Lucentite SAN (manufactured by Co-op Chemical Co., Ltd.)

‧Fluorine leveling agent: MEGAFAC F-471 (made by DIC Corporation) 0.1%

‧Solvent: Toluene

In addition, the amounts of resin particles (organic filler), first inorganic fine particles (colloidal silica) and second inorganic fine particles (synthetic bentonite) added to the coating solution for forming the optical functional layer are based on the following examples and The description of the comparative example will be described later. In addition, the added amount of each component is a ratio (mass %) of the total solid content of the coating liquid for forming an optical functional layer. Here, the total solid content of the coating liquid for forming an optical functional layer refers to components other than the solvent. Therefore, "the mixing ratio (mass %) of the resin particles, the first inorganic fine particles, and the second inorganic fine particles in the total solid content of the coating liquid for forming an optical functional layer" and "the cured film of the coating liquid for forming an optical functional layer" The content ratio (mass %) of the resin particles, the first inorganic fine particles, and the second inorganic fine particles in the optical functional layer is equal.

The measuring methods of the surface roughness of the optical laminate, the clarity of the transmitted image, the haze value, and the film thickness are as follows.

[Surface roughness]

The arithmetic average roughness Ra, the maximum height Rz, and the average length RSm of the curve elements are measured in accordance with JIS B0601:2001 using a surface roughness tester (Surfcorder SE1700α, manufactured by Kosaka Research Institute Co., Ltd.). The average angle of inclination was calculated based on ASEM95, and the average angle of inclination measured using the above-mentioned surface roughness measuring device was calculated, and the average angle of inclination was calculated according to the following formula.

Average tilt angle = arctan (average tilt)

[Breakthrough image sharpness]

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

[Haze value]

The haze value is measured in accordance with JIS K7105 using a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.). Here, the light The haze value of the layered film is regarded as the total haze. In addition, subtract the "haze value of the transparent sheet with adhesive" from "the haze value measured by attaching the transparent sheet with adhesive to the surface of the optical laminated film provided with fine unevenness" Value as internal haze. In addition, an acrylic adhesive material (thickness 10 μm) was applied to a polyethylene terephthalate film (thickness 38 μm) as a transparent sheet with an adhesive material.

[Film thickness]

The film thickness of the optical functional layer was measured using a linear gauge (D-10HS, manufactured by Ozaki Manufacturing Co., Ltd.).

(Relationship between resin particles and internal haze)

First, in order to obtain an internal haze (19 to 40%) in which both the scintillation resistance and the comparison are good, the necessary addition amount of the resin particles (organic filler) was investigated. A resin coating solution in which resin particles and two kinds of inorganic fine particles were added in the amounts described in Table 1 was prepared, and an optical laminate was produced according to the above-mentioned production method. The internal haze of the manufactured optical laminate is obtained.

Table 1 shows the amount of resin particles and two types of inorganic fine particles added and the internal haze value of the obtained optical laminate.

Figure 1 shows the relationship between the added amount of the resin particles (organic filler) described in Table 1 and the internal haze of the obtained optical laminate Make a plot of the points. The straight line shown in Figure 1 is the regression line obtained from the trace points.

It can be seen from the regression line shown in Figure 1 that when the refractive index difference between the base resin and the resin particles is 0.075, in order to make the internal haze value 19 to 40%, as long as the addition amount of the resin particles is 7 to 15% is enough.

(Examples 1-12, Comparative Examples 1-17)

Next, using the coating liquid for forming an optical functional layer in which resin particles and two types of inorganic fine particles were added in the amounts described in Table 2, optical laminates of Examples 1 to 12 and Comparative Examples 1 to 17 were prepared.

By the above test method, the haze value, the sharpness of the transmitted image and the film thickness of the optical laminates of Examples 1 to 12 and Comparative Examples 1 to 17 were measured.

(Evaluation methods and evaluation criteria of flicker resistance)

The scintillation resistance was evaluated in the following manner: the optical laminates of each example and each comparative example were bonded to the screen surface of a liquid crystal display (made by iPad3 (3rd generation) Apple Inc, 264ppi) via a transparent adhesive layer After going up, the liquid crystal display is put into a green display state, and when the liquid crystal display is observed from a place 50 cm vertically away from the center of the screen surface under a dark room, any 100 persons are visually judged whether to flicker. As a result of the evaluation, a person who did not feel flickering had 70 or more people as "○", 30 people or more and less than 70 people as "△", and less than 30 people as "×".

(Evaluation method and evaluation criteria of anti-glare property)

The anti-glare property was evaluated in the following manner: after the optical laminates of each example and each comparative example were laminated on a black acrylic plate (made by Sumitex 960 Sumitomo Chemical Co., Ltd.) via a transparent adhesive layer, the Photos When viewing at a distance of 50 cm vertically from the center of the black acrylic plate at a temperature of 250 lx, any 100 persons were allowed to visually determine whether their image (face) was reflected on the black acrylic plate. As a result of the evaluation, the case where 70 or more people did not feel reflected was "○", the case where 30 or more people and less than 70 people was "△", and the case where less than 30 people were "×".

(Evaluation method and evaluation standard of luminance ratio)

Luminance ratio, after bonding the optical laminate of each example and each comparative example and the translucent substrate to the screen surface of a liquid crystal display (iPad3 (3rd generation) Apple Inc, 264ppi) via a transparent adhesive layer The liquid crystal display was put into a white display state, and the luminance was measured in a dark room from a place 70 cm vertically from the center of the screen surface with a spectroradiometer (manufactured by SU-UL1R TOPCON Co., Ltd.). The brightness of the light-transmitting substrate is regarded as 100%, and the case of 93% or more is "○", and the case of less than 93% is "X".

Table 2 shows the amount of resin particles and two types of inorganic fine particles added, the total haze of the obtained optical laminate, the internal haze, the measured values of the clarity of the transmitted image and the thickness of the film, flicker resistance, anti-glare and brightness Than the evaluation results.

The total haze (Y) and internal haze (X) of the optical laminates of Examples 1 to 12 all satisfy the above conditional expressions (1) to (4), and the internal haze (X) is in the range of 19 to 40% Inside. In addition, the sharpness of the penetrating image is in a better range of 15-45%. Therefore, the optical laminates of Examples 1 to 12 have good flicker resistance, anti-glare properties and brightness ratio.

In contrast, in the optical laminates of Comparative Examples 1 and 2, the internal haze was less than 19%, so the scintillation resistance was insufficient. In addition, in the optical laminate of Comparative Example 2, the clarity of the transmitted image exceeds 50%, so the anti-glare property is also insufficient.

In the optical laminates of Comparative Examples 4, 5, 7, 8 and Comparative Examples 10 to 12, the sharpness of the transmitted image exceeded 50%, so the anti-glare property was insufficient.

In the optical laminates of Comparative Examples 13 to 17, the amount of resin particles was increased, so that the internal haze exceeded 40%, and the brightness ratio was insufficient. In addition, in the optical laminates of Comparative Examples 13 to 16, the total haze exceeded 57%, the surface unevenness was large, and the scintillation resistance was insufficient. In addition, in the optical laminates of Comparative Examples 13 to 15, even if the clarity of the transmitted image is less than 10%, the scintillation resistance deteriorates.

The optical laminates of Comparative Examples 3, 6 and 9 without colloidal silica as the first inorganic fine particles, although the haze value and the sharpness of the penetration image both satisfy the above-mentioned preferred range, are comparable to high-definition image display devices ( 264ppi) When combined, the flicker resistance deteriorates. This is because the concavo-convex structure formed on the surface of the optical functional layer of the optical laminates of Comparative Examples 3, 6 and 9 has an area where the adjacent concavo-convex height is 0.4 μm or more exceeds 3.5%. The detailed explanation on this point is as follows.

Figure 2 shows Examples 1 to 12 and Comparative Example 1 shown in Table 2. A graph showing the amount of resin particles and colloidal silica added in ~17. In FIG. 2, Examples 1 to 12 are plotted with black dots, and Comparative Examples 1 to 17 are plotted with X marks.

As shown in FIG. 2, it can be confirmed that the addition amount of the resin particles and the addition amount of colloidal silica in Examples 1 to 12 are the areas below the straight line shown by the solid line in FIG. 2 (where, except (On the horizontal axis), and when the amount of the resin particles added is in the range of 7 to 15%, even when used as an anti-glare film for high-definition image display devices of 200 ppi or more, flicker resistance and anti-glare properties And comparison can also get excellent performance. That is, it can be seen that when the content of the resin particles in the resin composition for forming an optical functional layer is A (%) and the content of colloidal silica is B (%), the following conditional expressions (5) and (6) are simultaneously satisfied In the case of, flicker resistance, anti-glare properties and contrast are all excellent. The following conditional expression (5) is a straight line passing through both the trace points of the addition amount of the resin particles and the addition amount of the colloidal silica in Examples 4 and 10. In addition, the following conditional expression (6), as described in FIG. 1, is a necessary condition for setting the internal haze value to be in the range of 19 to 40% in the configuration of this embodiment.

0<B≦0.375A-2.44. . . (5)

7.0≦A≦15.0. . . (6)

It can be seen from the results in Table 2 that, if conditional expressions (5) and (6) are not satisfied at the same time, any of the performances of flicker resistance, anti-glare, and comparison deteriorates, so it is not suitable for high-definition image display devices of 200 ppi or more Use of anti-glare film.

(The uneven shape of the surface of the optical function layer)

Here, the uneven shape on the surface of the optical functional layer will be described.

Table 3 shows the measured values of the surface roughness of the optical laminates of Examples 2 to 4 and Comparative Example 6.

FIG. 3 is a diagram showing the uneven shape of the surface of the optical functional layer of the optical laminate of Example 2, and FIG. 4 is a diagram showing the uneven shape of the surface of the optical functional layer of the optical laminate of Comparative Example 6. FIG.

Figures 3 and 4 use a non-contact surface-layer cross-sectional shape measurement system (measurement device: VertScanR3300FL-Lite-AC, analysis software: VertScan4, manufactured by Ryoka Systems Co., Ltd.) to measure the optical functional layer by optical interference The shape of the irregularities on the surface, and the measurement results are output as a three-dimensional image. Table 4 shows the measurement conditions of the measurement system.

As shown in Table 3, the arithmetic average roughness Ra, the maximum height Rz, and the average length RSm of the contour curve elements measured according to JIS B0601:2001, and the average inclination angle measured according to ASEM95, in Examples 2 to 4 and Comparative Examples The 6 are not considered to be particularly significant differences. However, if the surface irregularities of the optical functional layers of the optical laminates of Examples 2 to 4 and Comparative Example 6 are measured by optical interference, there is a difference in the distribution of the irregularities. The concave-convex shape of the surface of the optical functional layer of Example 2 shown in FIG. 3 is larger than the concave-convex shape of the surface of the optical functional layer of Comparative Example 6 shown in FIG. 4 (in FIG. 3 And the darker areas in Figure 4).

FIG. 5 is a graph showing the area ratio distribution of the unevenness height on the surface of the optical functional layer of Examples 2, 3 and Comparative Example 6, and FIG. 6 is an enlarged view in the dotted frame shown in FIG. 5.

The graphs shown in Figures 5 and 6 are created using the load curve analysis function of the above-mentioned non-contact surface and layer profile measurement system. Here, the height of the unevenness means the difference in height between the concave portion and the convex portion in a direction perpendicular to the measurement surface based on the average level (height 0) of the entire height of the unevenness of the measurement surface. In addition, the area ratio of the height of unevenness means the ratio of the area above the predetermined height of unevenness relative to the measured area.

It can be seen from FIGS. 5 and 6 that in Examples 2 and 3 in which colloidal silica was added as the first inorganic fine particles in the coating solution for forming the optical functional layer, compared with Comparative Example 6 in which colloidal silica was not added, the unevenness was high Relatively smaller. In addition, in Example 2 and Comparative Example 6, the area ratio of the unevenness of the optical functional layer of Example 2 is smaller than the area ratio of Comparative Example 6 regardless of the height of the unevenness. Also, Example 2 and the ratio Compared with Example 6, it was confirmed that there is a difference in the area ratio of the region having a roughness height of 0.4 μm or more. That is, I think that Example 2 can improve the flicker resistance by forming the uneven shape on the surface of the optical functional layer so that the area ratio of the area with the uneven height of 0.4 μm or more is 3.5% or less. On the contrary, I think that Comparative Example 6 has formed a large number of parts where the area ratio of the region with a bump height of 0.4 μm or more exceeds 3.5%, and the bump height as shown in FIG. 4 is relatively large. The measured value is not much different from Example 2, but the flicker resistance is deteriorated.

FIG. 7 is a cross-sectional STEM image of the optical functional layer of the optical laminate of Example 2 and FIG. 8 is a cross-sectional STEM image of the optical functional layer of the optical laminate of Comparative Example 6. FIG.

From the cross-sectional STEM image shown in FIG. 7, it can be confirmed that in the optical functional layer of Example 2, colloidal silica and synthetic bentonite form an aggregate. On the other hand, as shown in FIG. 8, the optical functional layer of Comparative Example 6 does not contain colloidal silica, so the aggregate as shown in FIG. 7 is not formed. The aggregate of colloidal silica and synthetic bentonite formed in the optical laminate of Example 2 is larger than the aggregate of synthetic bentonite present in the optical functional layer in Comparative Example 6, so the effect of suppressing the aggregation of resin particles is high .

As described above, it can be confirmed that the optical laminates of Examples 1 to 12, even when used as an anti-glare film of a high-definition image display device of 200 ppi or more, all of the flicker resistance, anti-glare property and contrast are available Play excellent performance.

[Industry availability]

The optical laminate of the present invention can be used as an anti-glare film for high-definition (for example, 200 ppi or more) image display devices.

Claims (8)

An optical layered body is an optical layered body formed by laminating at least one or more optical functional layers on a light-transmitting substrate, and is characterized in that a concave-convex shape is formed on at least one surface of the optical functional layer; The concave-convex optical functional layer contains at least a resin component hardened by the irradiation of free radiation or ultraviolet rays, resin particles aggregated in the resin component to form a fine concave-convex structure on the surface of the optical functional layer, and the excessiveness of the resin particles is suppressed The aggregated first inorganic fine particles and the second inorganic fine particles having cation exchange capacity and swelled by the introduction of the solvent; the amount of the first inorganic fine particles and the amount of the second inorganic fine particles are both 0.1 to 5.0%; the The optical laminate has an internal haze X and a total haze Y satisfying the following conditional expressions (1) to (4): Y>X‧‧‧(1) Y≦X+17‧‧‧(2) Y≦57‧ ‧‧(3) 19≦X≦40‧‧‧‧(4) The sharpness of the penetrating image using an optical comb with a width of 0.5mm is 10~50%; the content ratio of the resin particles in the optical function layer A(%) The content ratio B (%) of the first inorganic fine particles satisfies the following conditional expressions (5) and (6): 0<B≦0.375A-2.44‧‧‧‧(5) 7.0≦A≦15.0‧‧‧( 6) In the case of measuring the concave-convex shape on the outermost surface of the optical functional layer by optical interference, the area of the portion having a concave-convex height of 0.4 μm or more is 3.5% or less of the measurement area. The optical laminate according to claim 1, wherein the first inorganic fine particles contained in the optical functional layer are at least one selected from the group consisting of colloidal silica, alumina, and zinc oxide. The optical laminate according to claim 1 or 2, wherein the second inorganic fine particles contained in the optical functional layer are swelling clay. The optical laminate according to claim 1, wherein the optical functional layer includes one or more optical functional layers mainly composed of a radiation-curable resin composition. The optical laminate according to claim 1, wherein the first inorganic fine particles and the second inorganic fine particles contained in the optical functional layer form an aggregate. 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 is characterized in that it is formed by laminating a polarizing substrate on the translucent substrate constituting the optical layered body according to claim 1. A display device characterized by having an optical laminate as in claim 1.