WO2016103685A1

WO2016103685A1 - Optical laminate, polarizing plate, and display device

Info

Publication number: WO2016103685A1
Application number: PCT/JP2015/006400
Authority: WO
Inventors: 直樹芹澤; 隆之中西
Original assignee: 株式会社トッパンＴｏｍｏｅｇａｗａオプティカルフィルム
Priority date: 2014-12-26
Filing date: 2015-12-22
Publication date: 2016-06-30
Also published as: CN107111012A; TW201630743A; KR102443498B1; KR20170100555A; KR20220083841A; TWI650234B; JP6698552B2; KR102520205B1; CN107111012B; KR20230052311A; JPWO2016103685A1

Abstract

Provided is an optical laminate capable of suppressing glare and maintaining contrast and anti-glare properties even when applied to a high-definition image display panel. The optical laminate has at least one optically functional layer laminated onto a light-transmissive base. An optically functional layer has at least one irregularly profiled surface. An optically functional layer with an irregularly profiled surface contains at least a resin component, two types of inorganic fine particles, and resin particles. The optical laminate has an internal haze X and a total haze Y that satisfy the following conditional expressions (1) - (4): Y > X ∙∙∙ (1) Y ≤ X + 17 ∙∙∙ (2) Y ≤ 57 ∙∙∙ (3) 19 ≤ X ≤ 40 ∙∙∙ (4) The optical laminate has transmitted image clarity of 10 - 50 % when using an optical comb with a width of 0.5 mm. When measuring the surface roughness of the outermost surface of the optically functional layer using optical interferometry, the area having a roughness height of 0.4 µm or more occupies 3.5 % or less of the measured area.

Description

Optical laminate, polarizing plate and display device

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

Anti-glare film exhibits anti-glare properties by scattering external light with its surface uneven structure. The uneven structure on the surface of the antiglare film is formed by aggregating particles in the outermost resin layer.

Anti-glare films are required to have functions such as glare resistance and high contrast in addition to anti-glare properties. Conventionally, by adjusting the particle shape (filler) shape, particle size, refractive index, paint physical properties (viscosity), coating process, etc., the surface uneven structure (external scattering) and internal scattering are optimized to achieve anti-glare properties. Improvement of glare resistance and high contrast has been attempted. However, anti-glare properties, glare resistance, and high contrast are in a trade-off relationship.

Antiglare property is enhanced by using a filler with a large particle size, increasing the amount of filler added, and strengthening the filler aggregation. In this case, the antiglare property is enhanced by increasing the number of irregularities and the size of the irregularities, but the glare resistance deteriorates due to an increase in the lens effect.

The glare resistance is improved due to the increase in internal scattering due to the use of a filler having a large refractive index difference from the resin and the increase in the amount of filler added, but the contrast decreases because the diffused light increases. Further, by reducing the surface roughness, that is, by reducing the uneven average length Sm, the antiglare property is improved, but the antiglare property having a low white quality is noticeable.

Contrast improves by reducing internal scattering, but glare resistance deteriorates. In addition, although the contrast is improved by providing a low reflection layer, it is disadvantageous in terms of cost because of the multilayer structure.

Japanese Patent Laid-Open No. 10-20103

Due to the recent high definition of liquid crystal panels, glare will occur if the existing antiglare film maintains the antiglare and contrast as usual. On the other hand, in order to improve the glare resistance, it is necessary to sacrifice the antiglare property and contrast.

Therefore, the present invention provides an optical laminate capable of suppressing glare while maintaining antiglare properties and contrast when applied to an image display panel, particularly a high-definition image display panel of 200 ppi or more, and the same. An object is to provide a polarizing plate and an image display device used.

The present invention relates to an optical laminate in which at least one optical functional layer is laminated on a translucent substrate. A concave / convex shape is formed on at least one surface of the optical functional layer of the optical layered body, and the optical functional layer having the concave / convex shape contains at least a resin component, two types of inorganic fine particles, and resin particles. The laminate has an internal haze X that satisfies the following conditional expressions (1) to (4), and a total haze Y:
Y> X (1)
Y ≦ X + 17 (2)
Y ≦ 57 (3)
19 ≦ X ≦ 40 (4)
The transmitted image definition using an optical comb with a width of 0.5 mm is 10 to 50%, and when the surface unevenness shape of the outermost surface of the optical functional layer is measured by the optical interference method, the unevenness height is 0.4 μm or more. The area of a certain part is 3.5% or less of the measurement area.

ADVANTAGE OF THE INVENTION According to this invention, even when applied to a high-definition image display panel of 200 ppi or more, an optical laminate that can suppress glare while maintaining antiglare properties and contrast, and a polarizing plate and an image display using the same Equipment can be provided.

FIG. 1 is a graph plotting the relationship between the amount of resin particles (organic filler) added 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. 3 is a diagram illustrating the uneven shape on the surface of the optical functional layer of the optical laminate according to the second embodiment. FIG. 4 is a view showing the uneven shape of the optical functional layer surface of the optical layered body according to Comparative Example 6. FIG. 5 is a graph showing the distribution of the area ratio of the uneven height on the surface of the optical functional layer according to Example 2 and Comparative Example 6. FIG. 6 is an enlarged view in a broken-line frame shown in FIG. FIG. 7 is a cross-sectional STEM photograph of the optical functional layer of the optical layered body according to Example 2. FIG. 8 is a cross-sectional STEM photograph of the optical functional layer of the optical laminate according to Comparative Example 6. FIG. 9 is a cross-sectional view illustrating a schematic configuration of the optical layered body according to the embodiment. FIG. 10 is a cross-sectional view illustrating a schematic configuration of the polarizing plate according to the embodiment. FIG. 11 is a cross-sectional view illustrating a schematic configuration of the display device according to the embodiment.

FIG. 9 is a cross-sectional view showing a schematic configuration of the optical laminate according to the embodiment. The optical laminate 100 according to the embodiment includes a translucent substrate 1 and at least one optical functional layer 2 laminated on the translucent substrate 1. Fine irregularities are formed on the surface of the optical functional layer 2. The optical function layer 2 exhibits anti-glare properties by irregularly reflecting the diplomacy by the unevenness.

As the translucent substrate, polyethylene terephthalate (PET), triacetyl cellulose (TAC), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polycarbonate (PC), polyimide (PI), polyethylene (PE), polypropylene Various resin films such as (PP), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), cycloolefin copolymer (COC), norbornene resin, polyethersulfone, cellophane, and aromatic polyamide can be suitably used. .

The total light transmittance (JIS K7105) of the translucent substrate is preferably 80% or more, and more preferably 90% or more. The thickness of the translucent substrate is preferably 1 to 700 μm and more preferably 25 to 250 μm in consideration of the productivity and handling properties of the optical laminate.

The translucent substrate is preferably subjected to a surface modification treatment in order to improve adhesion with the optical functional layer. Examples of the surface modification treatment include alkali treatment, corona treatment, plasma treatment, sputtering treatment, application of a surfactant and a silane coupling agent, Si deposition, and the like.

The optical functional layer contains a base resin, resin particles (organic filler), and two types of inorganic fine particles. The optical functional layer is formed by applying a base resin that is cured by irradiation with ionizing radiation or ultraviolet rays, a resin composition in which resin particles and two kinds of inorganic fine particles are mixed, to a translucent substrate, and curing the coating film. Formed by.

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

As the base resin, a resin that can be cured by irradiation with ionizing radiation or ultraviolet rays can be used.

Resin materials that are cured by irradiation with ionizing radiation include radical polymerizable functional groups such as acryloyl group, methacryloyl group, acryloyloxy group, and methacryloyloxy group, and cationic polymerizable functional groups such as epoxy group, vinyl ether group, and oxetane group. Monomers, oligomers and prepolymers can be used alone or in admixture. Examples of the monomer include methyl acrylate, methyl methacrylate, methoxypolyethylene methacrylate, cyclohexyl methacrylate, phenoxyethyl methacrylate, ethylene glycol dimethacrylate, dipentaerythritol hexaacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate and the like. As oligomers and prepolymers, polyester acrylate, polyurethane acrylate, polyfunctional urethane acrylate, epoxy acrylate, polyether acrylate, acrylate compounds such as alkit acrylate, melamine acrylate, silicone acrylate, unsaturated polyester, tetramethylene glycol diglycidyl ether, 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- Oxeta such as ethyl-3-oxetanyl) methoxy] methyl} benzene, di [1-ethyl (3-oxetanyl)] methyl ether The compounds can be exemplified.

The above-described resin material can be cured by irradiation with ultraviolet rays under the condition that a photopolymerization initiator is added. Photopolymerization initiators include radical polymerization initiators such as acetophenone, benzophenone, thioxanthone, benzoin, and benzoin methyl ether, and cationic polymerization starts such as aromatic diazonium salts, aromatic sulfonium salts, aromatic iodonium salts, and metallocene compounds. The agents can be used alone or in combination.

Resin particles (organic filler) added to the optical functional layer aggregate in the base resin to form a fine concavo-convex structure on the surface of the optical functional layer. As the resin particles, those made of a light-transmitting resin material such as acrylic resin, polystyrene resin, styrene-acrylic copolymer, polyethylene resin, epoxy resin, silicone resin, polyvinylidene fluoride, and polyvinyl fluoride resin can be used. The refractive index of the resin particle material is preferably 1.40 to 1.75.

Further, the refractive index n _f of the resin particles and the refractive index _nz 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)

And refractive index n _z of a resin material as a base material, the refractive index of the resin particles and n _f, is not satisfied conditions (alpha), increasing the amount of resin particles to obtain the desired internal haze Necessary, and image sharpness deteriorates.

The average particle size 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 antiglare property is lowered. On the other hand, when the average particle diameter of the resin particles exceeds 10.0 μm, the area ratio of the uneven height on the surface of the optical functional layer cannot be controlled, and the glare resistance is deteriorated.

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

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, 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, locally increasing unevenness can be suppressed. By adding the first inorganic fine particles, the glare resistance can be improved while maintaining the antiglare property and the high contrast.

The first inorganic fine particles are preferably inorganic nanoparticles having an average particle size of 10 to 100 nm. When colloidal silica is used as the first inorganic fine particles, the average particle size is more preferably about 20 nm. When alumina or zinc oxide is used as the first inorganic fine particles, the average particle size is about 40 nm. More preferably. The amount of the first inorganic fine particles added is preferably 0.05 to 10%, 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 addition amount of the first inorganic fine particles is out of this range, the area ratio of the uneven height on the surface of the optical functional layer cannot be controlled, and the glare resistance deteriorates.

The second inorganic fine particles are preferably inorganic nanoparticles having an average particle diameter of 10 to 200 nm. The addition amount of the second inorganic fine particles is preferably 0.1 to 5.0%. As the second inorganic fine particles, swellable clay can be used. The swellable clay is not particularly limited as long as it has a cation exchange capacity and swells by taking in a solvent between the layers of the swellable clay, even if it is a natural product, it is a synthetic product (including substitution products and derivatives). May be. Moreover, the mixture of a natural product and a synthetic product may be sufficient. Examples of the swellable clay include mica, synthetic mica, vermiculite, montmorillonite, iron montmorillonite, beidellite, saponite, hectorite, stevensite, nontronite, magadiite, isallite, kanemite, layered titanic acid, smectite, and synthetic smectite. Etc. These swellable clays may 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 an organic onium ion introduced between the layers of the swellable clay. The organic onium ion is not limited as long as it can be organicized using the cation exchange property of the swellable clay. As the second inorganic fine particle, for example, synthetic smectite (layered organic clay mineral) can be used. Synthetic smectite functions as a thickener that increases the viscosity of the optical functional layer forming resin composition. Addition of the synthetic smectite as a thickener suppresses the sedimentation of the resin particles and the first inorganic fine particles, and contributes to the formation of an uneven structure on the surface of the optical functional layer.

Further, 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 aggregates in the optical functional layer. This agglomerate suppresses the aggregation of resin particles, and the unevenness height of the uneven shape on the surface of the optical functional layer is leveled, so that the scattering of light on the surface of the optical functional layer is made uniform and the glare resistance is improved. it can.

Further, a leveling agent may be added to the resin composition for forming the optical functional layer. The leveling agent has a function of being oriented on the surface of the coating film in the drying process, uniforming the surface tension of the coating film, and reducing surface defects of the coating film.

Furthermore, an organic solvent may be appropriately added to the resin composition for forming the optical functional layer. Examples of the organic solvent include alcohols, esters, ketones, ethers, and aromatic hydrocarbons.

The film thickness of the optical functional 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, curing failure due to oxygen inhibition occurs, and the scratch resistance of the optical functional layer tends to be lowered. On the other hand, when the film thickness of the optical functional layer exceeds 12.0 μm, curling due to curing shrinkage of the base resin layer becomes strong, which is not preferable.

Further, the film thickness of the optical functional layer is preferably 110 to 300%, more preferably 120 to 250% of the average particle diameter of the resin particles. When the film thickness of the optical functional layer is less than 110% of the average particle diameter of the resin particles, the antiglare property with low whiteness and outstanding quality is obtained. On the other hand, when the film thickness of the optical functional layer exceeds 300% of the average particle diameter of the resin particles, the antiglare property is insufficient, which is not preferable.

In the optical laminate according to this embodiment, the internal haze X and the total haze Y satisfy the following conditions (1) to (4) at the same time.
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 glare 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.

It is more preferable that the internal haze X satisfies the following conditional expression (4) ′. When the internal haze X satisfies the conditional expression (4) ′, both the glare resistance and the contrast can be further improved.
25 ≦ X ≦ 35 (4) ′

Further, when the total haze Y does not satisfy the conditional expression (3) and exceeds 57%, the surface of the optical functional layer has large irregularities and the glare resistance is insufficient.

The transmitted image definition of the optical laminate according to this embodiment is preferably 10 to 50%, more preferably 15 to 45%, as measured using a 0.5 mm wide optical comb. . When the transmitted image definition is less than 10%, the glare resistance is deteriorated. On the other hand, when the transmitted image clarity exceeds 50%, the antiglare property deteriorates.

When the uneven shape on the surface of the optical functional layer according to the present embodiment is measured by the optical interference method, the area of the portion where the uneven height is 0.4 μm or more is 3.5% or less. Of the concavo-convex structure on the surface of the optical functional layer, when the area of the concavo-convex height of 0.4 μm or more exceeds 3.5%, a large portion of locally concavo-convex parts is distributed, so that 200 ppi or higher image display When an optical laminate is used as the antiglare film of the device, the glare resistance is deteriorated.

Conventionally, in order to suppress excessive filler agglomeration, the method of adjusting the viscosity of paint, the method of increasing the concentration of paint solids during coating, and the use of a solvent with a high volatilization rate to suppress convection during drying Although methods have been adopted, there is a problem that surface failures such as coating unevenness tend to occur when these methods are adopted. On the other hand, as described in the above embodiment, since the method of adding two kinds of inorganic fine particles does not affect the physical properties of the paint and the drying speed, the glare resistance is maintained while maintaining the coating suitability. Can be improved.

FIG. 10 is a cross-sectional view showing a schematic configuration of the polarizing plate according to the embodiment. The polarizing plate 110 includes the optical laminate 100 and the polarizing film 11. The optical laminated body 100 is as shown in FIG. 9, and a polarizing film (polarizing substrate) 11 is provided on the surface of the translucent substrate 1 on which the optical functional layer 2 is not provided. The polarizing film 11 is obtained by laminating a transparent substrate 3, a polarizing layer 4, and a transparent substrate 5 in this order. The materials for the transparent substrates 3 and 5 and the polarizing layer 4 are not particularly limited, and those usually used for polarizing films can be used as appropriate.

FIG. 11 is a cross-sectional view illustrating a schematic configuration of the display device according to the embodiment. The display device 120 is obtained by 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 in this order. The polarizing film 12 is obtained by laminating a transparent substrate 6, a polarizing layer 7, and a transparent substrate 8 in this order. The materials of the

transparent substrates

6 and 8 and the polarizing layer 7 are not particularly limited, and those usually used for a 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 having transparent electrodes, and a color filter, and changes the orientation of the liquid crystal molecules according to the voltage applied between the transparent electrodes. By controlling the light transmittance, the light transmittance of each pixel is controlled to form an image. The backlight unit 14 includes a light source and a light diffusing plate (both not shown), and is an illumination device that uniformly diffuses light emitted from the light source and emits it from the emission surface.

Note that the display device 120 illustrated in FIG. 11 may further include a diffusion film, a prism sheet, a brightness enhancement film, a retardation film for compensating for a retardation of a liquid crystal cell or a polarizing plate, and a touch sensor.

The optical layered body according to the present embodiment further includes at least one layer of a refractive index adjusting layer such as a low refractive index layer, an antistatic layer, and an antifouling layer in addition to the optical functional layer for suppressing glare. Also good.

The low refractive index layer is a functional layer that is provided on the optical functional layer that suppresses glare and reduces the reflectance by reducing the refractive index of the surface. The low refractive index layer is formed by applying a coating solution containing an ionizing radiation curable material such as polyester acrylate monomer, epoxy acrylate monomer, urethane acrylate monomer, polyol acrylate monomer and a polymerization initiator, and polymerizing the coating film. It can be formed by curing. For the low refractive index layer, the low refractive particles include LiF, MgF, 3NaF.AlF or AlF (all with a refractive index of 1.4), or Na ₃ AlF ₆ (cryolite, with a refractive index of 1.33). Low refractive index fine particles made of a low refractive material such as the above may be dispersed. 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 voids can be made to have a refractive index of air (≈1), so that they can be low refractive index particles having 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 monomer, an epoxy acrylate monomer, a urethane acrylate monomer, a polyol acrylate monomer, a polymerization initiator, and an antistatic agent. It can be formed by curing by polymerization. Examples of the antistatic agent include antimony-doped tin oxide (ATO), metal oxide fine particles such as tin-doped indium oxide (ITO), polymer-type conductive compositions, and quaternary ammonium salts. Can be used. The antistatic layer may be provided on the outermost surface of the optical layered body, or may be provided between the optical functional layer that suppresses glare and the translucent substrate.

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

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

Hereinafter, examples in which the optical layered body according to the embodiment is specifically implemented will be described.

(Method for producing optical laminate)
A 40 μm thick triacetyl cellulose film was used as the translucent substrate. An optical functional layer was formed by applying the following coating solution for forming an optical functional layer on a translucent substrate, drying (volatilizing the solvent), and curing the coating film by polymerization.

[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 size 3.5 μm, refractive index 1.595
<Example 11>
Styrene monodisperse filler SSX302ABE (manufactured by Sekisui Plastics Co., Ltd.) Average particle size 2.0 μm, refractive index 1.595
<Example 12>
Cross-linked styrene monodisperse particles SX500H (manufactured by Soken Chemical Co., Ltd.) Average particle size 5.0 μm, refractive index 1.595
Colloidal silica: Organosilica sol MEK-ST (manufactured by Nissan Chemical Industries, Ltd.)
・ Synthetic smectite: Lucentite SAN (Coop Chemical Co., Ltd.)
・ Fluorine-based leveling agent: MegaFuck F-471 (manufactured by DIC Corporation) 0.1%
・ Solvent: Toluene

The addition amount of the resin particles (organic filler), the first inorganic fine particles (colloidal silica) and the second inorganic fine particles (synthetic smectite) to the coating solution for forming the optical functional layer is the same as in the following examples and comparative examples. It will be described later in the description. Moreover, the addition amount of each component is the ratio (mass%) which occupies for the total solid content mass of the coating liquid for optical function layer formation. Here, the total solid content of the coating solution for forming an optical functional layer refers to a component excluding the solvent. Therefore, the blending 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 the optical functional layer, and the cured film of the coating liquid for forming the optical functional layer The content ratio (% by mass) of the resin particles, the first inorganic fine particles, and the second inorganic fine particles in the optical functional layer is the same.

The method for measuring the surface roughness, transmitted image definition, haze value, and film thickness of the optical laminate is as follows.

[Surface roughness]
The arithmetic average roughness Ra, the maximum height Rz, and the average length RSm of the contour curve elements were measured according to JIS B0601: 2001 using a surface roughness measuring instrument (Surfcoder SE1700α, manufactured by Kosaka Laboratory Ltd.). The average inclination angle was determined according to ASEM95 using the surface roughness measuring instrument as described above, and the average inclination angle was calculated according to the following equation.
Average inclination angle = arctan (average inclination)

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

[Haze value]
The haze value was measured using a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K7105. Here, the haze value of the optical laminated film was defined as the total haze. In addition, the value obtained by subtracting the haze value of the transparent sheet with adhesive from the haze value measured by pasting the transparent sheet with adhesive on the surface provided with the fine uneven shape of the optical laminated film was defined as the internal haze. . In addition, as the transparent sheet with an adhesive material, a polyethylene terephthalate film (thickness 38 μm) coated with an acrylic adhesive material (thickness 10 μm) was used.

[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, the amount of resin particles (organic filler) added to obtain an internal haze (19 to 40%) that improves both glare resistance and contrast was examined. A resin coating solution in which resin particles and two kinds of inorganic fine particles were added in the addition amounts shown in Table 1 was prepared, and an optical laminate was produced according to the production method described above. The internal haze of the produced optical laminate was determined.

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.

FIG. 1 is a graph plotting the relationship between the amount of resin particles (organic filler) added in Table 1 and the internal haze of the obtained optical laminate. The straight line shown in FIG. 1 is a regression line obtained from the plot.

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

(Examples 1 to 12, Comparative Examples 1 to 17)
Next, optical laminates according to Examples 1 to 12 and Comparative Examples 1 to 17 were used by using a coating liquid for forming an optical functional layer in which resin particles and two types of inorganic fine particles were added in the addition amounts shown in Table 2. Was made.

For each of the produced optical laminates according to Examples 1 to 12 and Comparative Examples 1 to 17, the haze value, transmitted image definition, and film thickness were measured by the test methods described above.

(Evaluation method and evaluation criteria for glare resistance)
The glare resistance is determined by bonding the optical layered body of each example and each comparative example to the screen surface of a liquid crystal monitor (iPad3 (3rd generation) Apple Inc., 264 ppi) through a transparent adhesive layer. The monitor was put in a green display state, and the presence or absence of glare when the liquid crystal monitor was viewed from a place 50 cm vertically away from the center of the screen surface in a dark room was evaluated by visual judgment of 100 arbitrary persons. The evaluation results were “◯” when the number of people who did not feel glare was 70 or more, “Δ” when the number was 30 or more and less than 70, and “X” when the number was less than 30.

(Anti-glare evaluation method and evaluation criteria)
Anti-glare property is 50 cm vertically from the center of the black acrylic plate after the optical laminates of the examples and comparative examples are bonded to a black acrylic plate (Sumipex 960, manufactured by Sumitomo Chemical Co., Ltd.) via a transparent adhesive layer. The presence / absence of reflection of his / her image (face) on a black acrylic plate when viewed from a distant place under the condition of illuminance of 250 lx was evaluated by visual judgment of arbitrary 100 people. The evaluation result was “◯” when the number of people who did not feel the reflection was 70 or more, “△” when the number was 30 or more and less than 70, and “X” when the number was less than 30.

(Brightness ratio evaluation method and evaluation criteria)
The brightness ratio is obtained by bonding the optical layered body of each example and each comparative example and the translucent substrate to the screen surface of a liquid crystal monitor (iPad3 (3rd generation) Apple Inc., 264 ppi) through a transparent adhesive layer. After that, the liquid crystal monitor was set to a white display state, and the luminance was measured with a spectroradiometer (SU-UL1R manufactured by Topcon Co., Ltd.) from a location 70 cm away from the center of the screen surface in a dark room. When the luminance of the translucent substrate is 100%, the case of 93% or more is “◯”, and the case of less than 93% is “x”.

In Table 2, the addition amount of resin particles and two kinds of inorganic fine particles, the total haze, internal haze, transmitted image definition and film thickness of the obtained optical laminate, glare resistance, antiglare and The evaluation result of luminance ratio is shown.

The total haze (Y) and internal haze (X) of the optical laminates according to Examples 1 to 12 satisfy all the conditional expressions (1) to (4) described above, and the internal haze (X) is 19 to 40%. It was in the range. Further, the transmitted image definition was more preferably in the range of 15 to 45%. Therefore, the optical laminates according to Examples 1 to 12 were good in all of the glare resistance, antiglare property and luminance ratio.

On the other hand, in the optical laminates according to Comparative Examples 1 and 2, the internal haze was less than 19%, and thus the glare resistance was insufficient. Moreover, in the optical laminated body which concerns on the comparative example 2, since the transmitted image clarity exceeded 50%, anti-glare property was also inadequate.

In the optical laminates according to Comparative Examples 4, 5, 7, and 8 and Comparative Examples 10 to 12, the antiglare property was insufficient because the transmitted image clarity exceeded 50%.

In the optical laminates according to Comparative Examples 13 to 17, the internal haze exceeded 40% due to the increase in the amount of resin particles added, and the luminance ratio was insufficient in all cases. In addition, in the optical laminates according to Comparative Examples 13 to 16, the total haze exceeded 57%, the surface unevenness was large, and the glare resistance was insufficient. Further, in the optical laminates according to Comparative Examples 13 to 15, the glare resistance deteriorated even when the transmitted image definition was less than 10%.

The optical laminates according to Comparative Examples 3, 6 and 9 in which colloidal silica is not added as the first inorganic fine particles, although both the haze value and the transmitted image definition satisfy the above-described preferable ranges. When combined with a high-definition image display device (264 ppi), the glare resistance deteriorated. This is because, in the uneven structure formed on the surface of the optical functional layer of the optical laminate according to Comparative Examples 3, 6, and 9, the area of the adjacent uneven height of 0.4 μm or more exceeds 3.5%. It depends on. Details of this point will be described later.

FIG. 2 is a graph plotting the amount of resin particles added and the amount of colloidal silica added in Examples 1 to 12 and Comparative Examples 1 to 17 shown in Table 2. In FIG. 2, Examples 1 to 12 are plotted with black circles, and Comparative Examples 1 to 17 are plotted with crosses.

As shown in FIG. 2, the plots of the addition amount of resin particles and the addition amount of colloidal silica in Examples 1 to 12 are regions below the straight line shown in FIG. 2 (except on the horizontal axis). In addition, when the addition amount of the resin particles is within a range of 7 to 15%, even when used as an antiglare film for a high-definition image display device of 200 ppi or more, the antiglare and antiglare properties It was confirmed that excellent performance can be obtained with all the contrast. That is, when the resin particle content in the optical functional layer forming resin composition is A (%) and the colloidal silica content is B (%), the following conditional expressions (5) and (6) are satisfied. When satisfied at the same time, it was found to be excellent in all of glare resistance, antiglare property and contrast. The following conditional expression (5) is a straight line that passes through both the addition amount of the resin particles and the plot of the addition amount of colloidal silica in Examples 4 and 10. Further, the following conditional expression (6) is a necessary condition for setting the internal haze value within the range of 19 to 40% in the configuration of the present embodiment as described with reference to FIG.
0 <B ≦ 0.375A-2.44 (5)
7.0 ≦ A ≦ 15.0 (6)

As can be seen from the results in Table 2, when the conditional expressions (5) and (6) are not satisfied at the same time, any one of glare resistance, antiglare property, and contrast deteriorates, and thus a high-definition image display device of 200 ppi or more It was not suitable for use as an antiglare film.

(Uneven shape on the surface of the optical functional 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 according to Examples 2 to 4 and Comparative Example 6.

FIG. 3 is a view showing the uneven shape on the surface of the optical functional layer of the optical laminate according to Example 2, and FIG. 4 is a view showing the uneven shape on the surface of the optical functional layer of the optical laminate according to Comparative Example 6. is there.

3 and 4 show an optical function using a non-contact surface / layer cross-sectional shape measurement system (measuring device: Bartscan R3300FL-Lite-AC, analysis software: VertScan4, manufactured by Ryoka System Co., Ltd.) using an optical interference method. The uneven shape of the layer surface is measured, and the measurement result is 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, the average length RSm of the contour curve element, the average inclination angle measured according to ASEM95, measured according to JIS B0601: 2001, are compared with those in Examples 2 to 4. There is no particularly significant difference from Example 6. However, when the concavo-convex shape of the optical functional layer surface of the optical laminates according to Examples 2 to 4 and Comparative Example 6 is measured by the optical interference method, the distribution of the concavo-convex shape is different. Compared with the concavo-convex shape on the surface of the optical functional layer according to Comparative Example 6 shown in FIG. 4, the concavo-convex shape on the surface of the optical functional layer according to Example 2 shown in FIG. In FIG. 4, there are fewer dark spots).

FIG. 5 is a graph showing the distribution of the area ratio of the uneven height on the surface of the optical function layer according to Examples 2 and 3 and Comparative Example 6, and FIG. 6 is an enlarged view within the broken line frame shown in FIG. is there.

The graphs shown in FIG. 5 and FIG. 6 are created using the load curve analysis function of the non-contact surface / layer cross-sectional shape measurement system described above. Here, the uneven height refers to the level difference between the concave and convex portions in the direction orthogonal to the measurement surface, based on the average level (height 0) of all the uneven heights on the measurement surface. Further, the area ratio of the uneven height refers to the ratio of a region having a predetermined uneven height or more to the measurement area.

As can be seen from FIGS. 5 and 6, in Examples 2 and 3 in which colloidal silica was added as the first inorganic fine particles to the coating solution for forming an optical functional layer, compared to Comparative Example 6 in which no colloidal silica was added, The uneven height is relatively small. In addition, when Example 2 and Comparative Example 6 are compared, in the uneven shape of the optical functional layer according to Example 2, any uneven surface area ratio is smaller than the area ratio in Comparative Example 6. It was. Further, when Example 2 and Comparative Example 6 were compared, a difference was particularly recognized in the area ratio of the region where the unevenness height was 0.4 μm or more. That is, in Example 2, the anti-glare property was improved by forming the concavo-convex shape on the surface of the optical functional layer so that the area ratio of the region having the concavo-convex height of 0.4 μm or more was 3.5% or less. It is thought that. On the contrary, in Comparative Example 6, the area ratio of the region having the unevenness height of 0.4 μm or more exceeds 3.5%, and many portions with relatively large unevenness heights as shown in FIG. 4 are formed. Therefore, although the measured value of the general surface roughness is not so different from that of Example 2, it is considered that the glare resistance is deteriorated.

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

From the cross-sectional STEM photograph shown in FIG. 7, it can be confirmed that colloidal silica and synthetic smectite form aggregates in the optical functional layer according to Example 2. On the other hand, as shown in FIG. 8, since the optical functional layer according to Comparative Example 6 does not contain colloidal silica, aggregates as shown in FIG. 7 are not formed. Since the aggregate of colloidal silica and synthetic smectite formed in the optical laminate according to Example 2 is larger than the aggregate of synthetic smectite present in the optical functional layer according to Comparative Example 6, the aggregation of resin particles is suppressed. High effect.

As described above, even when the optical laminates according to Examples 1 to 12 are used as an antiglare film for a high-definition image display device of 200 ppi or more, they have a glare resistance, an antiglare resistance and a contrast. It was confirmed that excellent performance can be exhibited in all.

The optical laminate according to the present invention can be used as an antiglare film for use in a high-definition (for example, 200 ppi or more) image display device.

DESCRIPTION OF SYMBOLS 1 Translucent base | substrate 2 Optical

functional layer

3, 5, 6, 8 Transparent base material 4, 7

Polarizing layer

11, 12 Polarizing plate 13 Liquid crystal cell 14 Backlight unit 100 Optical laminated body 110 Polarizing plate 120 Display apparatus

Claims

An optical laminate in which at least one optical functional layer is laminated on a translucent substrate,
An uneven shape is formed on at least one surface of the optical functional layer,
The optical functional layer having the concavo-convex shape contains at least a resin component, two types of inorganic fine particles, and resin particles,
The optical laminate has an internal haze X that satisfies the following conditional expressions (1) to (4), and a total haze Y:
Y> X (1)
Y ≦ X + 17 (2)
Y ≦ 57 (3)
19 ≦ X ≦ 40 (4)
Transmission image definition using an optical comb with a width of 0.5 mm is 10 to 50%,
When the surface unevenness shape of the outermost surface of the optical functional layer is measured by a light interference method, the area of the portion where the unevenness height is 0.4 μm or more is 3.5% or less of the measurement area, Optical laminate.
The optical laminate according to claim 1, wherein the two types of inorganic fine particles contained in the optical functional layer are inorganic nanoparticles and swellable clay.
The content ratio A (%) of the resin particles in the optical functional layer and the content ratio B (%) of the inorganic nanoparticles satisfy the following conditional expressions (5) and (6): The optical laminate according to claim 2.
0 <B ≦ 0.375A-2.44 (5)
7.0 ≦ A ≦ 15.0 (6)
2. The optical laminate according to claim 1, wherein the optical functional layer is composed of one or more optical functional layers mainly composed of a radiation curable resin composition.
The optical laminate according to claim 1, wherein the two types of inorganic fine particles contained in the optical functional layer form an aggregate.
The optical laminate according to claim 1, further comprising at least one of a refractive index adjusting layer, an antistatic layer, and an antifouling layer.
A polarizing plate, wherein a polarizing substrate is laminated on the translucent substrate constituting the optical layered body according to claim 1.
A display device comprising the optical laminate according to claim 1.