KR20190005972A - Optical laminate, polarizing plate and display device - Google Patents

Abstract

The present invention provides an optical laminate suitable for use as a high-quality antireflective film capable of exhibiting a deep black display with less rough feeling, and a polarizing plate and an image display device using the same. Wherein at least one surface of the optical functional layer is provided with a concavoconvex shape and the transmission image clarity using a 0.5 mm wide optical comb is 70 to 95% , The product of the average area of the convex portions of the outermost surface of the optical function layer and the arithmetic average height Sa measured by the optical interference method is 4.7 to 44.0 탆 ³ and the average inclination angle 慮 a is 0.124 to 0.349 ° will be.

Description

Optical laminate, polarizing plate and display device

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

A functional film having antifogging property is provided on the outermost surface of a liquid crystal display or an organic EL display in order to improve the visibility of the image. The anti-glare film has a fine concavo-convex structure on its surface and diffuses the reflected light on the surface, thereby suppressing the regular reflection of the external light and preventing the external light from being reflected.

As a method of forming a functional film having a fine concavo-convex shape on the surface, a coating film containing a binder such as an ultraviolet curing resin and a fine particle (filler) is coated on a translucent substrate to form a coating film, The curing is generally carried out, and the dispersibility and various other characteristics can be adjusted according to the particle diameter and the addition amount of the fine particles (for example, see Patent Documents 1 and 2).

Japanese Patent Application Laid-Open No. 2002-196117 Japanese Patent Application Laid-Open No. 2008-158536

The conventional light-gauge film had a strong white appearance (white rice) of appearance when black was displayed on the display, and had a rough texture, resulting in a low-quality appearance.

Therefore, it is an object of the present invention to provide a high-quality optical laminate which is capable of displaying a deep black display with a flashing property, less rough feeling and gloss, and a polarizing plate and an image display device using the same.

The present invention relates to an optical laminate comprising at least one optical function layer laminated on a light transmitting substrate, wherein at least one surface of the optical function layer has a concavoconvex shape, and the transparent image clarity using an optical comb having a width of 0.5 mm Is 70 to 95%, the product of the average area of the convex portions of the outermost surface of the optical functional layer and the arithmetic average height Sa measured by the optical interference method is 4.7 to 44.0 탆 ³ , and the average tilt angle? A is 0.124 to 0.349 It is characterized by.

Further, the polarizing plate and the image display apparatus according to the present invention comprise the optical laminate.

According to the present invention, it is possible to provide a high-quality optical laminate capable of displaying a deep black color having a flashing property, less rough feeling, and gloss, and a polarizing plate and an image display device using the same.

1 is a cross-sectional view showing a schematic structure of an optical laminate according to an embodiment.
2 is a cross-sectional view showing a schematic configuration of a polarizing plate according to an embodiment.
3 is a cross-sectional view showing a schematic structure of a display device according to the embodiment.
4 is a graph plotting the relationship between the product of the average area of the convex portion and the arithmetic mean height Sa and the evaluation score of smoothness.
5 is a graph plotting the relationship between the average inclination angle and the evaluation score of black rice.
6 is a graph plotting the relationship between the average area of the convex portion and the product of the arithmetic average height Sa and the average inclination angle.

1 is a cross-sectional view showing a schematic structure of an optical laminate according to an 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. [ On the surface of the optical function layer 2, fine irregularities are formed. This irregularity causes irregular reflection of external light, so that the optical function layer 2 exhibits flicker.

Examples of the translucent base include polyethylene terephthalate (PET), triacetylcellulose (TAC), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polycarbonate (PC), polyimide (PI) (Polypropylene), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), cycloolefin copolymer (COC), norbornene-containing resin, polyether sulfone, cellophane, aromatic polyamide The film can be suitably used.

The total light transmittance (JIS K7105) of the translucent base is preferably 80% or more, more preferably 90% or more. The thickness of the light transmitting substrate is preferably 1 to 700 占 퐉, more preferably 25 to 250 占 퐉, in consideration of the productivity and handleability of the optical stacked body.

The light transmitting substrate is preferably subjected to a surface modification treatment to improve the adhesion with the optical functional layer. Examples of the surface modification treatment include an alkali treatment, a corona treatment, a plasma treatment, a sputtering treatment, a coating of a surfactant or a silane coupling agent, and a Si deposition.

The optical function layer contains a base resin, resin particles, and inorganic fine particles. The optical functional layer is formed by applying a coating liquid containing a base resin, a resin particle, and inorganic fine particles, which is cured by irradiation with ionizing radiation or ultraviolet rays, to a light-transmitting substrate and curing the coating film.

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

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

Examples of the resin material to be cured by irradiation with ionizing radiation include radical polymerizable functional groups such as acryloyl group, methacryloyl group, acryloyloxy group and methacryloyloxy group, and epoxy group, vinyl ether group and oxetane group Monomers, oligomers and prepolymers having cationic polymerizable functional groups may be used singly or in combination. Examples of the monomer include monomers such as methyl acrylate, methyl methacrylate, methoxypolyethylene methacrylate, cyclohexyl methacrylate, phenoxyethyl methacrylate, ethylene glycol dimethacrylate, dipentaerythritol hexaacrylate, trimethylolpropane tri Methacrylate, pentaerythritol triacrylate, and the like. Examples of oligomers and prepolymers include acrylate compounds such as polyester acrylate, polyurethane acrylate, polyfunctional urethane acrylate, epoxy acrylate, polyether acrylate, alkyd acrylate, melamine acrylate, and silicone acrylate; unsaturated poly Epoxy compounds such as ester, tetramethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, bisphenol A diglycidyl ether and various alicyclic epoxies, 3-ethyl- (3-ethyl-3-oxetanyl) methoxy] methyl} benzene, di [1-ethyl (3-oxetanyl)] methyl ether, etc. Oxetane compounds can be exemplified.

The resin material described above can be cured by irradiation with ultraviolet rays under the condition of the addition of a photopolymerization initiator. Examples of the photopolymerization initiator include radical polymerization initiators such as acetophenone, benzophenone, thioxanthone, benzoin and benzoin methyl ether, aromatic diazonium salts, aromatic sulfonium salts, aromatic iodonium salts and metallocene compounds The cationic polymerization initiator may be used singly or in combination.

The resin particles 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, those containing a light transmitting resin material such as an acrylic resin, a polystyrene resin, a styrene- (meth) acrylic acid ester copolymer, a polyethylene resin, an epoxy resin, a silicone resin, a polyvinylidene fluoride, have. The material refractive index of the resin particle is preferably 1.40 to 1.75. In order to adjust the refractive index or the dispersion of the resin particles, two or more kinds of resin particles having different materials (refractive indexes) may be mixed and used.

The average particle diameter of the resin particles is preferably 0.3 to 10.0 mu m, more preferably 1.0 to 7.0 mu m. When the average particle diameter of the resin particles is less than 0.3 占 퐉, the dispersibility is not sufficiently obtained. On the other hand, when the average particle diameter of the resin particles exceeds 10.0 mu m, the product of the average area of the convex portions and the arithmetic average height Sa becomes large, and the rough feeling becomes strong.

In the optical laminate according to the present embodiment, the content of the resin particles in the solid content of the optical function layer is 0.1 to 10.0%. When the content of the resin particles is less than 0.1%, the unevenness of the surface of the optical function layer is reduced, and the retardation is deteriorated. On the other hand, if the content of the resin particles exceeds 10.0%, the product of the average area of the convex portions and the arithmetic average height Sa becomes large, and the rough feeling becomes strong.

The inorganic fine particles added to the base resin of the optical functional 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 0.1 to 5.0%.

As the inorganic fine particles, for example, swellable clay can be used. The swellable clay may be a natural substance or a compound (including a substituent and a derivative), provided that it has a cation exchange capacity and swells by introducing a solvent between the layers of the swellable clay. It may also be a mixture of a natural product and a compound. As the swelling clay, there may be mentioned, for example, mica, synthetic mica, vermiculite, montmorillonite, iron montmorillonite, beellite, saponite, hectorite, stevensite, nontronite, magadiite, ailerite, , Smectite, and synthetic smectite. These swelling clays may be used either singly or in combination. As the inorganic fine particles, colloidal silica, alumina and zinc oxide may be used singly or in combination. In addition to the above-mentioned swelling clay, at least one 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 an organic onium ion introduced between the layers of the swellable clay. The organic onium ion is not limited as long as it can organize by utilizing the cation exchangeability of the swellable clay. As the inorganic fine particles, for example, synthetic smectite (layered organic clay mineral) can be used. The synthetic smectite functions as a thickener for increasing the viscosity of the resin composition for forming an optical functional layer. The addition of the synthetic smectite as a thickening agent suppresses the settling 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.

A leveling agent may be added to the resin composition for forming an optical functional layer. The leveling agent is oriented on the surface of the coating film in the drying process to uniformize the surface tension of the coating film and to reduce the surface defects of the coating film.

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; Glycol ethers such as ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, diethyl cellosolve, diethyl carbitol and propylene glycol monomethyl ether; Esters such as N-methylpyrrolidone, dimethylformamide, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate and amyl acetate; Ethers such as dimethyl ether and diethyl ether; Water, and the like, or a mixture of two or more thereof.

The film thickness of the optical function layer is preferably 1.0 to 10.0 mu m, more preferably 3.0 to 7.0 mu m. When the film thickness of the optical function layer is less than 1 탆, curing defects due to oxygen inhibition are generated and the scratch resistance of the optical function layer is likely to be lowered. On the other hand, if the film thickness of the optical function layer exceeds 10.0 탆, curling due to curing shrinkage of the base resin layer becomes strong, which is not preferable.

The transmission image clarity of the optical laminate according to the present embodiment is 70 to 95% as measured by using an optical comb having a width of 0.5 mm. If the transmission phase sharpness is less than 70%, the resultant is excessively dispersible and the visibility deteriorates. On the other hand, when the transmission phase sharpness exceeds 95%, the retardation is not 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 mean height Sa is 4.7 to 44.0 mu m < ^{3 &} gt ;. Here, the convex portion refers to a portion higher than the average surface passing through the average level passing through the vertexes of the convex portions and the lowermost point of the concave portions existing on the measurement surface, and the average area of the convex portions indicates the arithmetic average height Sa Sectional area average value of the convex portions. The arithmetic average height Sa is a value measured in accordance with ISO 25178, and is a parameter obtained by extending the arithmetic average roughness Ra in the plane direction. The product of the average area of the convex portions and the arithmetic average height Sa is an approximate value of the average volume of the convex portions existing on the average surface when each convex portion is modeled as a main body. The product of the average area of the convex portions and the arithmetic mean height Sa is an index indicating the size of convex portions existing on the average surface and is a parameter having a correlation with the smoothness and roughness of the surface of the optical function layer. When the product of the average area of the convex portions and the arithmetic mean height Sa is less than 4.7 mu m < ^{3 &} gt ;, the size of the convex portions formed on the surface of the optical function layer is too small. On the other hand, when the product of the average area of the convex portions and the arithmetic mean height Sa exceeds 44.0 mu m < ^{3 &} gt ;, the size of the convex portion formed on the surface of the optical function layer becomes too large and the rough feeling becomes strong.

The average inclination angle &thetas; a of the concavo-convex shape of the surface of the optical function layer according to the present embodiment is 0.124 to 0.349 DEG. The average inclination angle is an average value of angles formed by a straight line connecting the apex of the convex portion and the lowermost point of the concave portion adjacent to the convex portion with respect to the average surface, and is a value defined by? A = tan ^{- 1} ? A. In general,? A is a roughness curve of a concavo-convex section obtained by measuring the roughness profile using a contact-type surface roughness meter, and the peak of the convex portion in the reference length L and the lowest point of the concave portion adjacent to the convex portion The sum of the absolute values of the differences is divided by the reference length L. However, in the present invention, the value of the conventional? A is extended in the plane direction and calculated using all the convex portions and concave portions in the measurement plane measured by the optical interference method I took one value. When the average inclination angle &thetas; a is less than 0.124 DEG, the size of the convex portion formed on the surface of the optical function layer is too small, and therefore, sufficient anti-scattering property can not be obtained. On the other hand, when the average inclination angle &thetas; a is more than 0.349 DEG, the white rice becomes strong when the display is displayed in black.

The present inventors have newly found that the product of the transmission phase sharpness, the average area of the convex portion and the arithmetic average height Sa and the average inclination angle are parameters related to the flicker resistance, the smoothness (less rough feeling) and the black feeling (black rice) I got it. As described above, when the value of the transmission phase clarity is within a specific range, good diffusibility without deteriorating the visibility is obtained. In addition, the smaller the product of the average area of the convex portion and the arithmetic mean height Sa, the better the smoothing feeling, and the rougher the feeling is, the larger the sense of roughness increases (see FIG. The average inclination angle becomes smaller as the black rice becomes stronger, and the white rice increases as the size increases (see FIG. 5 to be described later). The present invention realizes a high-quality optical laminated body capable of achieving a deep black display with a good antiglare property, a less rough feeling, and a glossy appearance by selecting the above three parameters related to flame retardancy, smoothness and black rice .

Further, it is preferable that a random aggregation structure is formed in the optical function layer. The random agglomerate structure is a structure in which a first phase containing a relatively large amount of resin components and a second phase containing a relatively large amount of inorganic components exist in a three-dimensionally entangled state, and a second phase is present around the fine particles (resin particles) Lt; / RTI > structure. Since a random aggregation structure is formed in the optical function layer, fine irregularities can be reduced, and therefore, the blackness at the time of black display can be improved. The random flocculation structure can be formed, for example, by the method described in Japanese Patent No. 5802043.

2 is a cross-sectional view showing a schematic configuration of a polarizing plate according to an embodiment. The polarizing plate 110 includes an optical laminate 100 and a polarizing film 11. The optical laminate 100 is shown in Fig. 1, and a polarizing film (polarizing film) 11 is provided on the side of the light transmitting substrate 1 on which the optical function layer 2 is not provided. The polarizing film 11 is, for example, a transparent substrate 3, a polarizing layer 4, and a transparent substrate 5 laminated in this order. The materials of the transparent substrates 3 and 5 and the polarizing layer 4 are not particularly limited, and those commonly used for polarizing films can be suitably used.

3 is a cross-sectional view showing a schematic configuration of a display device according to the embodiment. The display device 120 includes the optical laminate 100, the polarizing film 11, the liquid crystal cell 13, the polarizing film (polarizing film) 12, and the backlight unit 14 in this order It is. The polarizing film 12 is, for example, a transparent substrate 6, a polarizing layer 7, and a transparent substrate 8 laminated in this order. The materials of the transparent substrates 6 and 8 and the polarizing layer 7 are not particularly limited, and those commonly used for polarizing films can be suitably 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. By changing the orientation of the liquid crystal molecules according to the voltage applied between the transparent electrodes, And controls the light transmittance of the pixel to form an image. The backlight unit 14 includes a light source and a light diffusing plate (both not shown), and is an illuminating device that uniformly diffuses the light emitted from the light source and emits the light from the emitting surface.

The display device 120 shown in Fig. 3 may further include a diffusion film, a prism sheet, a brightness enhancement film, a phase difference film for compensating a phase difference between the liquid crystal cell and the polarizing plate, and a touch sensor.

The optical laminate according to the present embodiment may further include 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 function layer for suppressing glare.

The low refractive index layer is a functional layer provided on the optical function layer and for reducing the reflectance by lowering the refractive index of the surface. The low refractive index layer is formed by applying a coating liquid containing an ionizing radiation curable material such as a polyester acrylate monomer, an epoxy acrylate monomer, a urethane acrylate monomer, a polyol acrylate monomer, etc. and a polymerization initiator, And then curing it. The low refractive index layer may be formed by dispersing low refractive index fine particles containing a low refractive index material such as LiF, MgF, 3NaF · AlF or AlF (all having a refractive index of 1.4) or Na ₃ AlF ₆ (cryoprocess, refractive index of 1.33) do. As the low refractive index fine particles, particles having voids inside the particles can be suitably used. In the case of a particle having a void in the particle, since the void portion can be made to have the refractive index (≒ 1) of air, low refractive index particles having a very low refractive index can be obtained. Specifically, by using low refractive index silica particles having voids in the interior thereof, the refractive index can be lowered.

The antistatic layer is formed by applying 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, Or the like. Examples of the antistatic agent include metal oxide fine particles such as antimony doped tin oxide (ATO) and tin-doped indium oxide (ITO), polymeric conductive compositions, quaternary ammonium salts, and the like. The antistatic layer may be provided on the outermost surface of the optical laminate, or between the optical functional layer and the light transmitting substrate.

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

At least one layer such as an infrared absorbing layer, an ultraviolet absorbing layer, and a color compensating layer may be formed in addition to the low refractive index layer, the antistatic layer and the antifouling layer, or in addition to the low refractive index layer, the antistatic layer and the antifouling layer.

Example

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

(Production method of optical laminate)

A coating liquid for forming an optical functional layer was prepared by mixing the materials shown below in the ratios shown in Table 1, and the adjusted coating liquid was applied to a triacetyl cellulose film (translucent substrate) having a thickness of 40 占 퐉. After the coating film was dried (solvent was volatilized), the coating film was irradiated with ultraviolet rays to be photo-cured to obtain optical laminated bodies according to Examples and Comparative Examples. The symbol " - " in Table 1 indicates that the corresponding material is not blended.

[Materials to be used for coating liquid for optical functional layer formation]

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

Resin particles: styrene-methyl methacrylate copolymer particles, refractive index 1.515, average particle diameter 2.0 占 퐉 or 3.5 占 퐉

· Inorganic fine particles 1: Synthetic smectite

· Inorganic fine particles 2: Alumina nanoparticles, average particle diameter 40 nm

Photopolymerization initiator: Irgacure 184 (manufactured by BASF Japan)

Solvent: Mixed solvent obtained by mixing toluene and isopropyl alcohol in a ratio of 16:37

The transmission phase clarity, the average inclination angle, the average area of the convex portions existing on the surface of the optical function layer and the arithmetic average height Sa of the optical laminate relating to Examples and Comparative Examples were measured by the following methods.

[Transmission Phase Sharpness]

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

[The product of the average inclination angle? A, the average area of the convex portion and the arithmetic average height Sa]

The concavo-convex shape of the outermost surface of the optically functional layer was measured by a light interference method using a noncontact surface / layer sectional shape measuring system (measuring device: Bertscan R3300FL-Lite-AC, analysis software VertScan4, manufactured by Rikagakusha K.K.) , And the measurement data was analyzed by the analysis software of the apparatus. The average inclination angle &thetas; a was calculated based on the data of the entire measurement area by using the inclination angle analysis function of the analysis software. The average area of the convex portion and the arithmetic mean height Sa were calculated using the particle analysis function of the analysis software.

The flame retardancy, film thickness condition, smoothness and black rice were evaluated according to the following evaluation methods.

[Evaluation method and evaluation criteria of smoothness and black rice]

The optical laminate of Examples and Comparative Examples was bonded to a black acrylic plate (SumiPex 960, made by Sumitomo Chemical Co., Ltd.) via a transparent adhesive layer. The surface of the optical laminate was observed at a position spaced 50 cm vertically from the center of the black acrylic plate by irradiating the light of a fluorescent lamp onto the black acrylic plate. The smoothness and the black rice were evaluated in five stages by sensory evaluation. The evaluation scores of 20 testees were averaged, and the average value was rounded to 0.5 intervals to give an evaluation score. When the evaluation score was 4 or more, it was judged that the feeling of smoothness or black rice was good.

<Evaluation Criteria of Smoothness>

5: No rough feeling, smooth texture

4: Less rough texture, a little smooth texture

3: Texture with rough texture and no smoothness

2: Rough feeling is slightly strong

1: Strong roughness

<Evaluation standards of black rice>

5: There is almost no diffuse reflection on the surface of the optical laminate, and a shiny deep color

4: Less diffused reflection on the surface of the optical laminate, shiny color

3: There is a slight diffuse reflection on the surface of the optical laminate,

2: strong white rice

1: strong white rice

Table 1 shows the composition of the coating composition for forming an optical functional layer used in Examples and Comparative Examples, the coating film thickness of the coating liquid, the transmission phase sharpness, the average inclination angle? A, the average area of the convex portion, And the evaluation results of black rice are summarized and shown.

The addition ratios of the respective components shown in Table 1 are the ratios (mass%) in the total solids mass of the coating solution for optical functional layer formation. Here, the total solid content of the coating liquid for forming an optical functional layer refers to a component excluding the solvent. Therefore, the mixing ratio (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 content ratio (mass%) of the resin particles and inorganic fine particles in the optical functional layer as the cured film of the optical functional layer- (Mass%) are equivalent.

Fig. 4 is a graph plotting the relationship between the average area of the convex portion and the arithmetic average height Sa and the evaluation score of smoothness. Fig. 5 is a graph plotting the relationship between the average inclination angle and the evaluation score of black rice. In the graphs of Figs. 4 and 5, values of all the examples and comparative examples shown in Table 1 are plotted.

4, the product of the average area of the convex portion and the arithmetic mean height Sa (that is, the convex portion volume approximate value of the average size) has a negative correlation with the evaluation score of smoothness, and the correlation is very high. It is also understood from FIG. 5 that there is a very high negative correlation between the average inclination angle and the evaluation score of black rice.

6 is a graph plotting the relationship between the average area of the convex portion and the product of the arithmetic average height Sa and the average inclination angle. In the graph of Fig. 6, the black circles are the plots of the embodiment, and the x marks are the plots of the comparative example.

As shown in Fig. 6, in the optical laminate of Examples 1 to 13, when the product of the average area of the convex portions and the arithmetic mean height Sa and the average inclination angle are in a constant range (In the range surrounded by the broken line in Fig. 6), it is understood that the surface smoothness and the black rice can be improved. More specifically, when the product of the average area of the convex portions and the arithmetic average height Sa is 4.7 to 44.0 탆 ³ and the average inclination angle 慮 a is 0.124 to 0.349,, there is no rough feeling, Can be realized.

As shown in Table 1, in the optical laminate of Examples 1 to 13, the transmission phase sharpness is 70 to 95%, the product of the average area of the convex portion and the arithmetic average height Sa and the average inclination angle? , It was confirmed that it is possible to display a deep black display having smoothness and gloss, even though it has a repulsive property.

On the other hand, in Comparative Examples 1 and 7 to 13, since the average inclination angle? A exceeded the upper limit (0.349 °) described above, the scattering of light on the surface of the optical function layer became excessive and the optical laminate .

In Comparative Examples 1, 2, 4, 5, 9, and 10, since the product of the average area of the convex portions and the arithmetic mean height Sa exceeds the upper limit value (44.0 탆 ³ ) described above, The size of the portion became large, and the optical laminate having rough feeling was obtained.

In Comparative Example 3, since the average inclination angle? A was lower than the lower limit (0.124 占 mentioned above, and the product of the average area of the convex portions and the arithmetic mean height Sa was less than the above lower limit value (4.7 占 퐉 ³ ) And black rice were all overvalued. However, since the size of the convex portion was too small, the transmission image clarity exceeded 95% and the retardation was insufficient. Similarly, in Comparative Example 4, since the product of the average area of the convex portions and the arithmetic mean height Sa is less than the above lower limit value (4.7 탆 ³ ), the size of the convex portions is too small, the transmission image clarity exceeds 95% It was insufficient.

The optical laminate according to the present invention can be used as an antiglare film for use in an image display device such as a liquid crystal display or an organic EL display. The optical laminate according to the present invention is suitable as an antiglare film particularly used in televisions because it has flame retardance, less rough feeling, and enables deep black display with gloss.

1: Transparent gas
2: optically functional layer
3, 5, 6, 8: transparent substrate
4, 7: Polarizing layer
11, 12: Polarizer
13: liquid crystal cell
14: Backlight unit
100: Optical laminate
110: polarizer
120: display device

Claims (6)

An optical laminate comprising at least one optical function layer laminated on a light transmitting substrate,
A concavo-convex shape is formed on at least one surface of the optical function layer,
The transmission image clarity using an optical comb having a width of 0.5 mm is 70 to 95%
The product of the average area of the convexes on the outermost surface of the optical function layer and the arithmetic average height Sa measured by the optical interference method is 4.7 to 44.0 탆 ³ ,
Wherein the average inclination angle? A is 0.124 to 0.349 °. The optical laminate according to claim 1, wherein the optical functional layer forms a random aggregation structure. The optical laminate according to claim 1 or 2, wherein the optical functional layer comprises at least one layer including a cured film of the radiation curable resin composition. 4. The optical laminate according to any one of claims 1 to 3, further comprising at least one of a refractive index adjusting layer, an antistatic layer and an antifouling layer. A polarizing plate characterized in that a polarizing body is laminated on the light transmitting substrate constituting the optical laminate according to any one of claims 1 to 4. A display device comprising the optical laminate according to any one of claims 1 to 4.

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