JP6674371B2 - Optical laminate, polarizing plate and display device - Google Patents

Description

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

  On the outermost surface of a liquid crystal display, an organic EL display, or the like, a functional film having an antiglare property is provided in order to improve the visibility of an image. The anti-glare film has a fine uneven structure on the surface, and suppresses the regular reflection of external light by diffusing surface reflected light, thereby preventing external light from being reflected.

  As a method of forming a functional film having fine irregularities on the surface, a coating liquid containing a binder such as an ultraviolet curable resin and fine particles (filler) is applied on a light-transmitting substrate to form a coating film. In general, a method of irradiating the coating film with ultraviolet rays to cure the coating film is used, and the anti-glare property and other properties are adjusted by the particle diameter and the amount of fine particles added (for example, see Patent Documents 1 and 2). Further, as described in Patent Document 3, it is also possible to form unevenness on the surface by a random aggregation structure.

JP 2002-196117 A JP 2008-158536 A Japanese Patent No. 5802043

  The conventional anti-glare film has a strong white appearance and a rough texture when black display is performed on a display, and has a low quality appearance.

  Therefore, the present invention provides a high-quality optical laminate having anti-glare properties, less roughness, and capable of providing a moist and deep black display, and a polarizing plate and an image display device using the same. The purpose is to:

The present invention relates to an optical laminate in which at least one optical functional layer is laminated on a light-transmitting substrate, wherein the optical functional layer contains at least a base resin and two types of inorganic fine particles, The two types of inorganic fine particles are synthetic smectite and alumina, and the surface of the optical function layer on the side opposite to the light- transmitting substrate has irregularities, and a transmission image using an optical comb having a width of 0.5 mm. a sharpness 82-95%, unevenness was measured by an optical interference method, the product of the average area and the arithmetic average height Sa of the convex portion of the outermost surface of the optical function layer is 10～33Myuemu ^3, uneven The shape is characterized in that the average inclination angle θa is 0.10 to 0.211 °. Here, the average area of the convex portion is, when the surface passing through the average level of the apex of the convex portion and the lowest point of the concave portion present on the outermost surface of the optical function layer is the average surface, the convex portion in the average surface Is the average value of the cross-sectional area.

  Further, a polarizing plate and an image display device according to the present invention include the above optical laminate.

  According to the present invention, it is possible to provide a high-quality optical laminate having antiglare properties, less roughness, and capable of providing a moist and deep black display, and a polarizing plate and an image display device using the same.

Sectional view showing a schematic configuration of an optical laminate according to an embodiment. Sectional view showing a schematic configuration of a polarizing plate according to an embodiment. Sectional view showing a schematic configuration of a display device according to an embodiment. Graph in which the relationship between the particle size of the filler and the amount added in Examples and Comparative Examples is plotted

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of the optical laminate according to the embodiment. The optical laminate 100 according to the embodiment includes a light-transmitting substrate 1 and at least one optical function layer 2 laminated on the light-transmitting substrate 1. Fine irregularities are formed on the surface of the optical function layer 2. The irregularities reflect diplomacy irregularly, so that the optical function layer 2 exhibits an antiglare property.

  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-containing 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. Further, the thickness of the light-transmitting substrate is preferably 1 to 700 μm, more preferably 25 to 250 μm, in consideration of the productivity and the handling properties of the optical laminate.

  The translucent substrate is preferably subjected to a surface modification treatment in order to improve the 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 or a silane coupling agent, Si deposition, and the like.

  The optical functional layer is formed by applying a coating liquid containing at least a base resin curable by irradiation with ionizing radiation or ultraviolet rays and inorganic fine particles to a translucent substrate and curing the coating film. Resin particles (filler) may be further added to the coating liquid for forming the optical functional layer.

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

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

  Examples of the resin material that is 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 as a mixture. Examples of the monomer include methyl acrylate, methyl methacrylate, methoxypolyethylene methacrylate, cyclohexyl methacrylate, phenoxyethyl methacrylate, ethylene glycol dimethacrylate, dipentaerythritol hexaacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate. Oligomers and prepolymers include acrylate compounds such as polyester acrylate, polyurethane acrylate, polyfunctional urethane acrylate, epoxy acrylate, polyether acrylate, 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-mentioned resin material can be cured by irradiation with ultraviolet light, provided that a photopolymerization initiator is added. Examples of the photopolymerization initiator include radical polymerization initiators such as acetophenone-based, benzophenone-based, thioxanthone-based, benzoin, and benzoin-methylether, and cationic polymerization initiators such as aromatic diazonium salts, aromatic sulfonium salts, aromatic iodonium salts, and metallocene compounds. The agents can be used alone or in combination.

  The inorganic fine particles added to the base resin of the optical function layer are preferably inorganic nanoparticles having an average particle diameter of 10 to 200 nm. The addition amount of the inorganic fine particles is preferably from 0.1 to 5.0%.

  As the inorganic fine particles, for example, swellable clay can be used. The swellable clay may have any cation exchange ability and swell by taking in a solvent between layers of the swellable clay, and may be a natural product or a synthetic product (including a substituted product and a derivative). You may. Further, a mixture of a natural product and a synthetic product may be used. Examples of the swelling clay include mica, synthetic mica, vermiculite, montmorillonite, iron montmorillonite, beidellite, saponite, hectorite, stevensite, nontronite, magadiite, islarite, kanemite, layered titanic acid, smectite, synthetic smectite And the like. One of these swellable clays may be used, or a plurality of them may be used as a mixture. Further, colloidal silica, alumina, and zinc oxide may be used alone or as a mixture as the inorganic fine particles. In addition to the swellable clay described above, one or more of colloidal silica, alumina, and zinc oxide may be used in combination.

  As the inorganic fine particles, a layered organic clay is more preferable. In the present invention, the layered organic clay refers to a material obtained by introducing an organic onium ion between layers of a swellable clay. The organic onium ion is not limited as long as it can be organized by utilizing the cation exchange property of the swellable clay. As the inorganic fine particles, for example, synthetic smectite (layered organic clay mineral) can be used. Synthetic smectite functions as a thickener for increasing the viscosity of the resin composition for forming an optical functional layer. The addition of a synthetic smectite as a thickener suppresses the sedimentation of the resin particles and the inorganic fine particles, and contributes to the formation of the uneven structure on the surface of the optical functional layer.

  The resin particles (fillers) aggregate in the base resin to form a fine uneven structure on the surface of the optical function layer. Without blending the resin particles, by forming a random aggregation structure in the optical functional layer, it is also possible to impart a concavo-convex structure required for antiglare expression, but by including the resin particles in the optical functional layer, The size and number of the irregularities on the surface of the optical function layer can be easily adjusted. The resin particles are made of a translucent resin material such as an acrylic resin, a polystyrene resin, a styrene- (meth) acrylate copolymer, a polyethylene resin, an epoxy resin, a silicone resin, a polyvinylidene fluoride, and a polyfluoroethylene resin. Anything can be used. The material of the resin particles preferably has a refractive index of 1.40 to 1.75. In order to adjust the refractive index and the dispersion of the resin particles, two or more types of resin particles having different materials (refractive index) may be mixed and used.

When resin particles are used, the average particle diameter A (μm) and the content ratio B (%) of the resin particles in the optical function layer satisfy the following conditional expression (1).
0 <B ≦ −2.33A + 9.67 (where A> 0) (1)
If the average particle size A and the content ratio B of the resin particles do not satisfy this condition, the product of the later-described average inclination angle, the average area of the projections, and the arithmetic average height Sa is out of the preferable range, and The feeling and the whiteness at the time of black display become strong, and the appearance quality of the optical laminate decreases.

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

  Further, an organic solvent may be appropriately added to the resin composition for forming an optical functional layer. Examples of the organic solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, butanol, isopropyl alcohol (IPA), and isobutanol; ketones such as acetone, methyl ethyl ketone (MEK), cyclohexanone, and methyl isobutyl ketone (MIBK). Ketone alcohols such as diacetone alcohol; aromatic hydrocarbons such as benzene, toluene and xylene; glycols such as ethylene glycol, propylene glycol and hexylene glycol; ethylcellosolve, butylcellosolve, ethylcarbitol; Glycol ethers such as butyl carbitol, diethyl cellosolve, diethyl carbitol, propylene glycol monomethyl ether; N-methylpyrrolidone, dimethylformamide, milk Methyl, ethyl lactate, methyl acetate, ethyl acetate, esters such as amyl acetate; dimethyl ether, and diethyl ether; of such water, can be used as a mixture of two or more.

  The thickness of the optical functional layer is preferably from 1.0 to 10.0 μm, and more preferably from 3.0 to 7.0 μm. When the thickness of the optical functional layer is less than 1 μm, poor curing due to oxygen inhibition occurs, and the scratch resistance of the optical functional layer tends to decrease. On the other hand, if the thickness of the optical functional layer exceeds 10.0 μm, the curl due to curing shrinkage of the base resin layer is undesirably increased.

  In the optical laminate according to the present embodiment, the transmitted image clarity measured using an optical comb having a width of 0.5 mm is 70 to 95%. The transmitted image definition is a parameter related to the antiglare property. In the optical laminate according to the present embodiment, when the value of the transmitted image clarity is within this range, good antiglare properties that do not impair visibility are obtained. If the transmitted image clarity is less than 70%, excessive anti-glare properties are obtained, and visibility deteriorates. On the other hand, if the transmitted image definition exceeds 95%, the antiglare property cannot be sufficiently obtained.

In the optical laminate according to the present embodiment, the product of the average area of the convex portions on the outermost surface of the optical function layer measured by the optical interference method and the arithmetic average height Sa is 10 to 35 μm ³ . Here, the convex portion refers to a portion higher than this average surface when the average surface passing through the average level of the vertexes of all the convex portions and the lowest point of the concave portion present on the measurement surface is used as a reference. The average area of the portion is an average value of the cross-sectional area of the convex portion on the average surface . The arithmetic average height Sa is a value measured in accordance with ISO 25178, and is a parameter obtained by expanding the arithmetic average roughness Ra in the plane direction. Represents the average of the absolute values of the deviations. The product of the average area of the projections and the arithmetic average height Sa corresponds to an approximate value of the average volume of the projections present on the average surface when each projection is modeled as a column. The product of the average area of the convex portions and the arithmetic average height Sa is an index indicating the size of the convex portions present on the average surface, and correlates with the smoothness (low roughness) of the optical functional layer surface. This is a parameter that has potential. The smoothness becomes better as the product of the average area of the projections and the arithmetic average height Sa is smaller, and the roughness becomes larger as the product becomes larger. In the present embodiment, when the product of the average area of the projections and the arithmetic average height Sa is less than 10 μm ³ , the size of the projections formed on the surface of the optical functional layer is too small, and the smoothness is good. However, sufficient antiglare property cannot be obtained. On the other hand, when the product of the average area of the projections and the arithmetic average height Sa exceeds 35 μm ³ , the size of the projections formed on the surface of the optical function layer is too large, and the roughness is increased.

In addition, the average inclination angle θa of the uneven shape on the surface of the optical function layer according to the present embodiment is 0.10 to 0.40 °. The average inclination angle is an average value of an angle formed by a straight line connecting the vertex of the convex portion and the lowest point of the concave portion adjacent to the convex portion with respect to the average surface, and is defined by θa = tan ⁻¹ Δa. It is. Δa is, in general, the roughness profile is measured using a stylus-type surface roughness meter, and in the roughness curve of the concave-convex cross section obtained by the measurement, the peak of the convex portion within the reference length L and this This is a value obtained by dividing the sum of absolute values of the difference between the lowest point of the concave portion adjacent to the convex portion and the reference length L. In the present invention, the conventional value of Δa is extended in the surface direction, and The value was calculated using all the protrusions and recesses in the measurement plane measured by the interference method. The average inclination angle θa is a parameter correlated with blackness. The blackness increases as the average inclination angle decreases, and the whiteness increases as the average inclination angle increases. In the present embodiment, when the average inclination angle θa is less than 0.10 °, the blackness at the time of black display becomes strong, but the antiglare property is sufficient because the size of the convex portion formed on the optical function layer surface is too small. Can not be obtained. On the other hand, when the average inclination angle θa exceeds 0.40 °, whiteness becomes strong when black is displayed on the display.

  Further, in the optical laminate according to the present embodiment, it is preferable that a random aggregation structure is formed in the optical functional layer. The random aggregation structure is such that a first phase containing a relatively large amount of a resin component and a second phase containing a relatively large amount of an inorganic component are three-dimensionally intertwined, and the second phase is It refers to a structure unevenly distributed around fine particles (resin particles). By forming a random aggregation structure in the optical function layer, fine irregularities can be reduced, so that antiglare properties and blackness during black display can be improved. The random aggregation structure can be formed by, for example, a method described in Japanese Patent No. 5802043.

  FIG. 2 is a cross-sectional view illustrating 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 laminate 100 is the one shown in FIG. 1, and a polarizing film (polarizing substrate) 11 is provided on a surface of the translucent substrate 1 on which the optical functional layer 2 is not provided. The polarizing film 11 is obtained by, for example, laminating a transparent substrate 3, a polarizing layer 4, and a transparent substrate 5 in this order. The materials of the transparent substrates 3 and 5 and the polarizing layer 4 are not particularly limited, and those usually used for a polarizing film can be appropriately used.

  FIG. 3 is a cross-sectional view illustrating a schematic configuration of the display device according to the embodiment. The display device 120 includes an optical laminate 100, a polarizing film 11, a liquid crystal cell 13, a polarizing film (polarizing substrate) 12, and a backlight unit 14 stacked in this order. The polarizing film 12, for example, 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 a voltage applied between the transparent electrodes. This is an apparatus that forms an image by controlling the light transmittance of each pixel. The backlight unit 14 is a lighting device that includes a light source and a light diffusing plate (neither is shown), and uniformly diffuses light emitted from the light source and emits the light from the emission surface.

  The display device 120 shown in FIG. 3 may further include a diffusion film, a prism sheet, a brightness enhancement film, a retardation film for compensating a retardation of a liquid crystal cell or a polarizing plate, and a touch sensor.

  The optical laminate according to the present embodiment has 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 that suppresses glare. Is also good.

The low-refractive-index layer is a functional layer provided on the optical functional layer to reduce the refractive index of the surface to reduce the reflectance. For the low refractive index layer, a coating liquid containing an ionizing radiation-curable material such as a polyester acrylate-based monomer, an epoxy acrylate-based monomer, a urethane acrylate-based monomer, a polyol acrylate-based monomer, and a polymerization initiator is applied, and the coating film is polymerized. It can be formed by curing. In the low-refractive-index layer, as low-refractive particles, LiF, MgF, 3NaF.AlF or AlF (all of which have a refractive index of 1.4) or Na ₃ AlF ₆ (cryolites, refractive index of 1.33) Low refractive index fine particles made of a low refractive material such as In addition, as the low refractive index fine particles, particles having voids inside the particles can be suitably used. In the case of particles having voids inside the particles, the voids can be made to have the 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 reduced by using low refractive index silica particles having voids therein.

  The antistatic layer, a polyester acrylate-based monomer, epoxy acrylate-based monomer, urethane acrylate-based monomer, ionizing radiation-curable materials such as polyol acrylate-based monomer, a polymerization initiator, and applying a coating liquid containing an antistatic agent, It can be formed by curing by polymerization. Examples of the antistatic agent include metal oxide-based fine particles such as antimony-doped tin oxide (ATO) and 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 laminate, or may be provided between the optical functional layer and the light transmitting 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 a silicon oxide, a fluorine-containing silane compound, a fluoroalkylsilazane, a fluoroalkylsilane, a fluorine-containing silicon-based compound, a perfluoropolyether group-containing silane coupling agent, or the like. .

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

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

(Method for producing optical laminate)
A coating solution for forming an optical functional layer containing the following materials was prepared, and the prepared coating solution was applied to a 40 μm-thick triacetyl cellulose film (light-transmitting substrate). After the coating film was dried (the solvent was volatilized), the coating film was irradiated with ultraviolet rays and light-cured to obtain optical laminates according to Examples and Comparative Examples.

[Materials used for coating liquid for forming optical functional layer]
The amount of each component added is a ratio (% by mass) in the total solid content (100 parts by mass) of the coating liquid for forming an optical functional layer. The addition amount of the base resin was adjusted according to the addition amount of the resin particles so that the total solid content was 100 parts by mass.
-Base resin: UV / EB curable resin Light acrylate PE-3A (pentaerythritol triacrylate, manufactured by Kyoeisha Chemical Co., Ltd.), refractive index 1.52
87.7 to 92.7 parts by massResin particles (filler): styrene-methyl methacrylate copolymer particles, refractive index 1.515, average particle size and amount added are as described in Table 1. Inorganic fine particles 1: Synthetic smectite 0.5 parts by mass, inorganic fine particles 2: alumina nanoparticles, average particle size 40 nm 2.0 parts by mass, photopolymerization initiator: Irgacure 184 (manufactured by BASF Japan) 4.8 parts by mass. And isopropyl alcohol at a ratio of 16:37.

  The transmission image clarity, the average inclination angle, the average area of the convex portions existing on the surface of the optical functional layer, and the arithmetic average height Sa of the optical laminates according to the examples and the comparative examples were measured by the following methods.

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

[Product of average inclination angle θa, average area of convex portions, and arithmetic average height Sa]
Optical interference method using the non-contact surface / layer cross-sectional shape measurement system (Measuring device: Bertscan R3300FL-Lite-AC, analysis software: VertScan4, manufactured by Ryoka Systems Inc.) , And the measured data was analyzed by the analysis software of the apparatus. The average inclination angle θa was calculated based on the data of the entire measurement area using the inclination angle analysis function of the analysis software. Further, the average area and the arithmetic average height Sa of the convex portions were calculated using the particle analysis function of the analysis software.

  The smoothness and darkness were evaluated according to the following evaluation methods.

[Evaluation method and evaluation criteria for smoothness and darkness]
The optical laminates of Examples and Comparative Examples were attached to a black acrylic plate (Sumipex 960, manufactured by Sumitomo Chemical Co., Ltd.) via a transparent adhesive layer. The light of a fluorescent lamp was reflected on the black acrylic plate, the surface of the optical laminate was observed vertically from a position 50 cm away from the center of the black acrylic plate, and the smoothness and blackness were evaluated by a sensory evaluation on a 5-point scale. The evaluation points of the 20 testers were averaged, and the value obtained by rounding the average value in increments of 0.5 was used as the evaluation score. When the evaluation score was 4 or more, it was determined that the smoothness or blackness was good.
<Evaluation criteria for smoothness>
5: Smooth texture with no roughness 4: Slightly smooth texture with little roughness 3: Texture with roughness and no smoothness 2: Slightly rough 1: Slightly rough <Evaluation of blackness Criteria>
5: There is almost no diffuse reflection on the surface of the optical laminate, and there is little moist and deep color. Whitish color 2: slightly whitish 1: strong whitish

  Table 1 shows the particle size and the amount of the filler used in the coating liquid for forming an optical functional layer according to the examples and the comparative examples, the coating film thickness of the coating liquid, the transmitted image clarity, the average inclination angle θa, and the convex portions. And the evaluation results of the product of the average area and the arithmetic average height Sa, the smoothness, and the darkness are collectively shown.

  In addition, the addition amount of the filler shown in Table 1 is a ratio (% by mass) in the total solid content mass 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 a component excluding a solvent. Therefore, the mixing ratio (% by mass) of the resin particles and the inorganic fine particles in the total solid content of the coating liquid for forming an optical functional layer, and the resin particles in the optical functional layer which is a cured film of the coating liquid for forming an optical functional layer And the content (% by mass) of the inorganic fine particles.

As shown in Table 1, in the optical laminates according to Examples 1 to 7, the transmitted image clarity measured using an optical comb having a width of 0.5 mm was in the range of 70 to 95%, and the average of the convex portions was obtained. When the product of the area and the arithmetic average height Sa is within the range of 10 to 35 μm ³ and the average inclination angle θa is within the range of 0.10 to 0.40 °, good antiglare properties are exhibited. In addition, it was confirmed that an optical laminated body capable of displaying a moist, deep black display with no smoothness and roughness was realized. Furthermore, from the optical laminated bodies according to Examples 2 to 7, the average inclination angle θa is 0.16 or more and 0.40 or less, and the product of the convex average area and the arithmetic average height Sa is 10 or more and 30 or less. As a result, high smoothness and moist black display can be realized at the same time. Furthermore, from the optical laminated bodies according to Examples 5 to 7, the average inclination angle θa is 0.27 or more and 0.40 or less, and the product of the convex average area and the arithmetic average height Sa is 10 or more and 25 or less. As a result, higher smoothness and a moist black display can be realized at the same time, so that it was confirmed that this was more preferable.

On the other hand, in Comparative Examples 1 to 5, the average inclination angle θa exceeded 0.40 °, and the product of the average area of the convex portions and the arithmetic average height Sa also exceeded 35 μm ³ , so that roughness was noticeable, Whiteness during black display has increased.

  FIG. 4 is a graph in which the relationship between the particle size of the filler and the amount added is plotted in Examples and Comparative Examples. In the graph of FIG. 4, black circles are plots of the example, and crosses are plots of the comparative example. In Example 1 in which no filler was added, both the particle size A of the filler and the amount B of the filler were plotted as zero.

As shown in FIG. 4, in the optical laminates according to Examples 1 to 7, the particle size (average particle size) and the addition amount of the filler in the convex portion are within a certain range (the region below the broken line in FIG. 4). In some cases, the average inclination angle, the product of the average area of the protrusions and the arithmetic average height Sa fall within the preferred range described above, and as a result, the smoothness of the surface and the blackness of black display may be improved. all right. Specifically, when a filler is added, the particle size A (average particle size; μm) of the filler and the amount (%) of the filler added may satisfy the following condition (1).
0 <B ≦ −2.33A + 9.67 (where A> 0) (1)

Further, from Examples 2 to 7 in FIG. 4 and Table 1, the particle diameter A (average particle diameter; μm) and the addition amount B (%) of the filler in the convex portion are within a certain range satisfying the following condition (2). (In the region between the double dashed line and the single dashed line in FIG. 4), the average inclination angle, the product of the average area of the projections and the arithmetic average height Sa fall within the more preferable range described above, It has been found that it exhibits anti-glare properties and can simultaneously realize a high smoothness and a moist and deep black display.
-2.33A + 4.00≤B≤-2.33A + 9.67 (however, A> 0)
... (2)

Further, from Examples 5 to 7 in FIG. 4 and Table 1, a certain range in which the particle size A (average particle size; μm) and the added amount B (%) of the filler in the convex portion satisfy the following condition (3): 4 (in the range of not less than the double dashed line and not more than the single dashed line in FIG. 4 and in the range of 0.5 ≦ B ≦ 5 and 1.5 ≦ A ≦ 3.5), the average inclination angle and the convexity The product of the average area and the arithmetic average height Sa is within the above-described more preferable range, exhibits excellent anti-glare properties, and has the most preferable effect of simultaneously realizing higher smoothness and moist deep black display. I found that.
0.5 ≦ B ≦ −2.33A + 9.67 ≦ 5 (1.5 ≦ A ≦ 3.5)
... (3)

  As described above, according to the optical laminate of the present invention, the transmission image clarity, the average inclination angle θa, and the product of the average area of the convex portions and the arithmetic average height Sa are all within the above-described ranges. , It was confirmed that a smooth, moist and deep black display was possible while having antiglare properties.

  The optical laminate according to the present invention can be used as an antiglare film used for an image display device such as a liquid crystal display or an organic EL display. The optical laminate according to the present invention has an antiglare property, has less roughness, and enables a moist and deep black display, and is therefore particularly suitable as an antiglare film used for a television.

REFERENCE SIGNS LIST 1 translucent substrate 2 optical function layer 3, 5, 6, 8 transparent substrate 4, 7 polarizing layer 11, 12 polarizing plate 13 liquid crystal cell 14 backlight unit 100 optical laminate 110 polarizing plate 120 display device

Claims (7)

An optical laminate in which at least one or more optical functional layers are laminated on a light-transmitting substrate,
The optical functional layer contains at least a base resin and two types of inorganic fine particles, and the two types of inorganic fine particles are synthetic smectite and alumina,
An uneven shape is formed on the surface of the optical function layer opposite to the light- transmitting substrate side ,
The transmitted image clarity using an optical comb having a width of 0.5 mm is 82 to 95%,
The uneven shape was measured by an optical interference method, the product of the average area and the arithmetic average height Sa of the convex portion of the outermost surface of the optical function layer is 10～33Myuemu ^3,
The optical laminate , wherein the uneven shape has an average inclination angle θa of 0.10 to 0.211 °.
Here, the average area of the convex portion, when the surface passing through the average level of the vertex of the convex portion and the lowest point of the concave portion present on the outermost surface of the optical function layer, the average surface, It is an average value of the cross-sectional area of the convex portion.   The optical laminate according to claim 1, wherein the optical functional layer has a random aggregation structure. 3. The optical device according to claim 1, wherein the average particle size A (μm) and the content ratio B (%) of the resin particles in the optical function layer satisfy the following conditional expression (1). 4. Laminate.
0 <B ≦ −2.33A + 9.67 (where A> 0) (1)   The optical laminate according to any one of claims 1 to 3, wherein the optical functional layer comprises one or more layers formed of a cured film of a radiation-curable resin composition.   The optical laminate according to claim 1, further comprising at least one of a refractive index adjustment layer, an antistatic layer, and an antifouling layer.   A polarizing plate, comprising: a polarizing substrate laminated on the light-transmitting substrate constituting the optical laminate according to claim 1.   A display device comprising the optical laminate according to claim 1.

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