JP6212844B2 - Optical film, polarizing plate, liquid crystal panel, and image display device - Google Patents

Description

  The present invention relates to an optical film, a polarizing plate, a liquid crystal panel, and an image display device.

  An image display surface of an image display device such as a liquid crystal display (LCD), a cathode ray tube display device (CRT), a plasma display (PDP), an electroluminescence display (ELD), a field emission display (FED) or the like is usually free of external light. An antireflection film provided with an antireflection layer on the outermost surface for suppressing reflection and an antiglare film provided with unevenness on the outermost surface are provided.

  The antireflection film mainly comprises a light-transmitting substrate, a hard coat layer provided on the light-transmitting substrate, and a low refractive index layer provided as an antireflection layer provided on the hard coat layer. I have. The antireflection film reduces reflected light itself by canceling out light reflected on the surface of the low refractive index layer and light reflected on the interface between the low refractive index layer and the hard coat layer. In such an antireflection film, the light reflected at the interface between the light transmissive substrate and the hard coat layer due to the difference in refractive index between the light transmissive substrate and the hard coat layer, and the low refractive index layer There is a problem in that the light reflected at the interface between the hard coat layer and the hard coat layer interferes to generate an iridescent uneven pattern called interference fringes.

  For such problems, when forming the hard coat layer on the light transmissive substrate, the components of the composition for the hard coat layer are infiltrated into the upper portion of the light transmissive substrate, so that the hard layer in the light transmissive substrate is hardened. Near the interface with the coating layer, a mixed region is formed in which the components of the light-transmitting substrate and the components of the hard coating layer are mixed, and the mixed region reduces the refractive index difference between the light-transmitting substrate and the hard coating layer. Thus, a technique that can prevent the occurrence of interference fringes has been developed (see, for example, Patent Document 1).

  However, in the antireflection film, since the surface of the hard coat layer is flat, it is necessary to form a mixed region having a sufficient thickness in order to prevent the occurrence of interference fringes. In addition, when a mixed region having a sufficient thickness is formed, the mixed region is relatively soft, so that the desired hardness cannot be obtained in the antireflection film unless the hard coat layer on the mixed region is thickened. is there. Therefore, it is necessary to apply the hard coat layer composition thickly on the light-transmitting substrate, and there is a problem that the manufacturing cost increases.

  On the other hand, the anti-glare film includes a light-transmitting substrate and an anti-glare layer provided on the light-transmitting substrate, and the surface of the anti-glare layer has fine particles contained in the anti-glare layer. The resulting unevenness is formed (see, for example, Patent Document 2). According to the antiglare film, external light can be diffusely reflected by the irregularities on the surface of the antiglare layer. It is also possible to impart hard coat properties to the antiglare layer by a binder resin that supports fine particles. In the antiglare film, the interference fringes can be made invisible due to the irregularities on the surface of the antiglare layer, so that it is not necessary to provide a mixed region and the thickness of the antiglare layer is made thinner than the hard coat layer of the antireflection film. be able to.

  However, in recent years, it has been required to add brightness to an image observed through an antiglare film. Under such a tendency, the surface of the antiglare layer is gently smoothed while securing the antiglare property, and an antiglare film having a haze of 5% or less is also becoming popular. As a result, the trouble that an interference fringe is visually recognized also arises in the anti-glare film.

  Further, as a recent trend, for example, as disclosed in Patent Document 3, it is possible to eliminate the problem of nitrite by adjusting the retardation, so that not only an optically isotropic substrate but also an optically anisotropic substrate can be used as a light-transmitting substrate for an antiglare film. Isotropic substrates have also been used. As will be described later, such an optically anisotropic base material has high solvent resistance and is difficult to permeate the solvent. Therefore, it is difficult to mix the components of the light-transmitting base material and the hard coat layer. For this reason, it has become impossible to apply interference fringe countermeasures using mixed regions to all transmissive substrates. In the first place, the countermeasure against interference fringes using the mixed region is not preferable in that the cost increases as described above.

JP 2003-131007 A JP 2011-81118 A JP2011-107198A

  The present invention has been made in consideration of the above points. In an optical film having a birefringent light-transmitting substrate and an antiglare layer in the plane, an image observed through the optical film can be obtained. It is an object to make it possible to impart shine and to suppress the occurrence of azimuth and interference fringes.

The optical film according to the present invention comprises:
A light transmissive substrate having birefringence in the surface;
An antiglare layer provided on the light-transmitting substrate, and an optical film comprising:
The light transmissive substrate has a retardation of 3000 nm or more,
The transmission definition measured using an optical comb having a width of 0.125 is 85% or less, and the haze is 5% or less.

  In the optical film according to the present invention, the antiglare layer may include a binder resin, organic fine particles, and inorganic fine particles, and the inorganic fine particles may be densely distributed in the binder resin.

  In the optical film according to the present invention, the aggregates of the inorganic fine particles may be densely distributed around the organic fine particles.

In the optical film according to the present invention, the light transmissive substrate has a refractive index (n _x ) in a slow axis direction that is the direction in which the refractive index is the largest in the plane of the light transmissive substrate, and the slow axis. the difference between the fast-axis refractive index of the direction perpendicular to the direction _{(n y) (n x -n} y) may be 0.05 to 0.20.

  The optical film according to the present invention further includes a low refractive index layer provided adjacent to the antiglare layer and having a refractive index lower than that of the antiglare layer, and the low refractive index layer is formed of the optical film. You may make it make the surface.

  In the optical film according to the present invention, the light-transmitting substrate may be a polyester substrate.

The polarizing plate according to the present invention is
Any of the optical films according to the invention described above;
A polarizing element provided on the side opposite to the side on which the antiglare layer is provided in the light transmissive substrate of the optical film.

  The liquid crystal display panel according to the present invention includes either the optical film according to the present invention described above or the polarizing plate according to the present invention described above.

  The image display device according to the present invention includes either the optical film according to the present invention described above or the polarizing plate according to the present invention described above.

The method for producing an optical film according to the present invention includes:
A light transmissive substrate having birefringence in the surface;
A method for producing an optical film comprising an antiglare layer provided on the light transmissive substrate,
The retardation of the light transmissive substrate is set to 3000 nm or more,
The transmission clarity measured using a 0.125 width optical comb is set to 85% or less and the haze is set to 5% or less.

The method for designing an optical film according to the present invention includes:
A light transmissive substrate having birefringence in the surface;
A method of designing an optical film comprising an antiglare layer provided on the light transmissive substrate,
The retardation of the light transmissive substrate is set to 3000 nm or more,
The transmission clarity measured using a 0.125 width optical comb is set to 85% or less and the haze is set to 5% or less.

  ADVANTAGE OF THE INVENTION According to this invention, a brightness can be provided to the image observed through an optical film, and generation | occurrence | production of a nitrile and an interference fringe can be suppressed effectively.

FIG. 1 is a diagram showing a layer configuration of the optical film according to the first embodiment. FIG. 2 is a diagram for explaining a method of measuring θa. FIG. 3 is an electron micrograph showing an example of a cross section of the optical film according to the first embodiment actually produced. FIG. 4 is a diagram illustrating a modification of the layer configuration of the optical film according to the first embodiment. FIG. 5 is a schematic diagram showing how the transmission clarity of the optical film according to the first embodiment is measured by a transmission clarity measurement device. FIG. 6 is a schematic configuration diagram of a polarizing plate according to the first embodiment. FIG. 7 is a schematic configuration diagram of the liquid crystal panel according to the first embodiment. FIG. 8 is a schematic configuration diagram of a liquid crystal display which is an example of the image display apparatus according to the first embodiment. FIG. 9 is a schematic configuration diagram of an optical film according to the second embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. Note that, in the drawings attached to the present specification, except for the photograph of FIG. 3, for the sake of convenience of illustration and understanding, the scale and the vertical / horizontal dimension ratio are appropriately changed and exaggerated from those of the actual ones.

(First embodiment)
First, an optical film according to a first embodiment of the present invention, a polarizing plate including the optical film, a liquid crystal display panel, and an image forming apparatus will be described with reference mainly to FIGS. In the present specification, terms such as “film”, “sheet”, and “plate” are not distinguished from each other only based on the difference in names. Therefore, for example, “film” is a concept including a member that can also be called a sheet or a plate. As a specific example, the “optical film” includes members called “optical sheet”, “optical plate”, and the like.

≪Optical film≫
As shown in FIG. 1, the optical film 10 has at least a light-transmitting base material 11 having birefringence in a plane and an antiglare layer 12 provided on the light-transmitting base material 11. doing. The light transmissive substrate 11 has a retardation Re of 3000 nm or more. The surface of the antiglare layer 12 is formed as an uneven surface 12A. And the transmission clarity of the optical film 10 measured using the 0.125 width | variety optical comb is 85% or less, and the haze of the optical film 10 is 5% or less. According to such an optical film 10, the generation of interference fringes can be effectively prevented, as will be described later.

  In the optical film 10 shown in FIG. 1, the adhesion for improving the adhesion between the light transmissive substrate 11 and the antiglare layer 12 between the light transmissive substrate 11 and the antiglare layer 12. A property improving layer 13 is provided. Moreover, in order to improve the adhesiveness at the time of joining the optical film 10 to another member, as shown by a two-dot chain line in FIG. 1, on the side opposite to the adhesive improvement layer 13 of the light transmissive substrate 11, A second adhesion improving layer 14 may be provided.

<Light transmissive substrate>
The light transmissive substrate 11 is an optically anisotropic substrate having visible light transmittance. The light transmissive substrate 11 has at least an in-plane birefringence. As will be described in detail later, such a light-transmitting substrate 11 is generally excellent in terms of mechanical properties, transparency, stability to heat, etc., and extremely advantageous in terms of cost.

  However, when such an optically anisotropic light-transmitting substrate 11 is superimposed on a display device such as a liquid crystal display panel that forms an image by the light of one linearly polarized light component, it is observed as a color pattern called Nijimura. An uneven pattern occurs. In order to cope with this nidimra, the light transmissive substrate 11 has a retardation of 3000 nm or more. If it is a light-transmitting base material having a retardation of 3000 nm or more, even if the light-transmitting base material is incorporated in an image display device, it is possible to effectively suppress the occurrence of nitrimula in the display image of the image display device. Although the details of the mechanism that can make Nijimura invisible are unclear, by giving a high retardation to the light-transmitting substrate 11, the light that caused Nizimura has a more continuous spectral distribution, As a result, it is expected that it will no longer be visually recognized as unevenness exhibiting a unique color.

  In addition, by using such a light transmissive substrate 11 having a high retardation, the following effects can be obtained which are superior to those of an optically isotropic substrate such as a triacetyl cellulose substrate that has been widely used heretofore. . When an optically isotropic substrate is superimposed on a display device such as a liquid crystal display panel that forms an image with light of one linearly polarized light component, an observer wearing polarized glasses represented by sunglasses Depending on the direction of the absorption axis, there is a problem that the image on the image display device cannot be observed brightly, and further that the image on the image display device cannot be observed. On the other hand, when using the optically anisotropic light-transmitting substrate 11, in particular, the light-transmitting substrate 11 having a high retardation of 3000 nm or more, the polarization is compared with the case of using the optically isotropic substrate. The image could be observed brighter regardless of the direction of the absorption axis of the glasses. In such a phenomenon, the polarization state of the image light projected from the display device is disturbed by the optically anisotropic light-transmitting substrate 11, particularly, the light-transmitting substrate 11 having a high retardation of 3000 nm or more. It is estimated that In recent years, the usage environment of display devices has rapidly diversified, and is widely applied to, for example, portable devices and devices used outdoors. With such diversification of usage modes of the display device, it is expected that a situation in which the observer observes the display device with the polarized glasses attached will occur more frequently. The application to the optical film 10 of the transparent base material 11, especially the light-transmissive base material 11 of the high retardation of 3000 nm or more is very useful.

  The retardation is an index that represents the degree of in-plane birefringence. From the viewpoint of preventing azimuth and thinning, it is more preferably 6000 nm or more and 25000 nm or less, and further preferably 8000 nm or more and 20000 nm or less.

Retardation Re (unit: nm) is the refractive index (n _x ) in the direction having the highest refractive index (slow axis direction) in the plane of the light-transmitting substrate, and the direction orthogonal to the slow axis direction (fast phase) Using the refractive index (n _y ) in the axial direction and the thickness d (unit: nm) of the light-transmitting substrate, it is expressed by the following formula (1).
_{Re = (n x -n y)} × d ... (1)

Retardation can be set to a measured value by setting the measurement angle to 0 ° and the measurement wavelength to 548.2 nm using, for example, KOBRA-WR manufactured by Oji Scientific Instruments. The retardation can also be obtained by the following method. First, using two polarizing plates, determined the orientation direction of the light-transmitting substrate, the refractive index of the two axes orthogonal to the orientation axis (n _{x, n y)} of an Abbe refractometer (NAR-4T manufactured by Atago Co., Ltd.) Here, an axis showing a larger refractive index is defined as a slow axis. Further, the thickness of the light-transmitting substrate is measured using, for example, an electric micrometer (manufactured by Anritsu). Then, by using the refractive index obtained, refractive index difference _(n x _-n y) _{(hereinafter,} the n x -n _y referred to as [Delta] n) was calculated, the refractive index difference [Delta] n and the light-transmitting substrate The retardation can be obtained by the product of the thickness d (nm).

  From the viewpoint of setting the retardation of the light transmissive substrate 11 to 3000 nm or more, the refractive index difference Δn is preferably 0.05 to 0.20. When the refractive index difference Δn is less than 0.05, the thickness necessary for obtaining the retardation value described above may be increased. On the other hand, if the refractive index difference Δn exceeds 0.20, it is necessary to make the draw ratio excessively high, so that tearing, tearing, etc. are likely to occur, and the practicality as an industrial material may be significantly reduced. More preferably, the lower limit of the refractive index difference Δn is 0.07, and the upper limit of the refractive index difference Δn is 0.15. In addition, when refractive index difference (DELTA) n exceeds 0.15, depending on the kind of the light transmissive base material 11, durability of the light transmissive base material 11 in a moisture-heat resistance test may be inferior. From the viewpoint of ensuring excellent durability in the heat and humidity resistance test, a more preferable upper limit of the refractive index difference Δn is 0.12.

As the refractive indices _{n x} in the slow axis direction of the light-transmitting substrate 11 is preferably 1.60 to 1.80, more preferable lower limit is 1.65, more preferable upper limit is 1.75 is there. As the refractive index _{n y} in the fast axis direction of the light transmitting substrate 11 is preferably 1.50 to 1.70, more preferable lower limit is 1.55, more preferable upper limit is 1.65 is there. By the refractive index n _y in the refractive indices n _x and the fast axis direction in the slow axis direction of the light transmitting substrate 11 is in the above range, and is satisfied the relationship of the above-mentioned refractive index difference [Delta] n, more preferably The inhibitory effect of Nijimura can be obtained.

  The thickness of the light-transmitting substrate 11 is not particularly limited, but can usually be 5 μm or more and 1000 μm or less, and the lower limit of the thickness of the light-transmitting substrate 11 is preferably 15 μm or more from the viewpoint of handling properties. 25 μm or more is more preferable. The upper limit of the thickness of the light transmissive substrate 11 is preferably 80 μm or less from the viewpoint of thinning.

  When a polyester substrate having a retardation of 3000 nm or more is used as the light transmissive substrate 11, the thickness of the polyester substrate is preferably 15 μm or more and 500 μm or less. When the thickness is less than 15 μm, the retardation of the polyester base material cannot be increased to 3000 nm or more, the anisotropy of mechanical properties becomes remarkable, and tearing, tearing, etc. are likely to occur, and the practicality as an industrial material is significantly reduced. There is. On the other hand, when it exceeds 500 μm, the flexibility specific to the polymer film is lowered, and the practicality as an industrial material may be lowered. The minimum with more preferable thickness of the said polyester base material is 50 micrometers, a more preferable upper limit is 400 micrometers, and a still more preferable upper limit is 300 micrometers.

  The light-transmitting substrate 11 is not particularly limited as long as it has a retardation of 3000 nm or more, and examples thereof include an acrylic substrate, a polyester substrate, a polycarbonate substrate, and a cycloolefin polymer substrate. Among these, a polyester base material is preferable from the viewpoint of cost and mechanical strength.

  Examples of the acrylic base material include a poly (meth) methyl acrylate base material, a poly (meth) ethyl acrylate base material, and a (meth) methyl acrylate- (meth) butyl acrylate copolymer base material. .

  Examples of the polyester base material include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), and polyethylene-2,6-naphthalate.

  The polyester used for the polyester substrate may be a copolymer of the above-mentioned polyester, and the polyester is the main component (for example, a component of 80 mol% or more), and a small proportion (for example, 20 mol% or less) It may be blended with a kind of resin. Polyethylene terephthalate or polyethylene-2,6-naphthalate is particularly preferable as the polyester because of good balance between mechanical properties and optical properties. In particular, polyethylene terephthalate is preferable because it is highly versatile and easily available. In the present invention, an optical film capable of producing a liquid crystal display device with high display quality can be obtained even if the film is extremely versatile, such as polyethylene terephthalate. Furthermore, polyethylene terephthalate is excellent in transparency, heat or mechanical properties, can be controlled by stretching, has a large intrinsic birefringence, and can obtain a large retardation relatively easily even when the film thickness is small.

  For example, as a method of obtaining a polyester base material having a retardation of 3000 nm or more, a polyester such as polyethylene terephthalate is melted, and the unstretched polyester extruded and formed into a sheet shape is transversal using a tenter or the like at a temperature equal to or higher than the glass transition temperature. A method of performing a heat treatment after stretching is mentioned. The transverse stretching temperature is preferably 80 to 130 ° C, more preferably 90 to 120 ° C. Further, the transverse draw ratio is preferably 2.5 to 6.0 times, more preferably 3.0 to 5.5 times. When the transverse draw ratio exceeds 6.0 times, the transparency of the resulting polyester base material tends to be lowered, and when the draw ratio is less than 2.5 times, the draw tension becomes small. The birefringence of the material is reduced, and the film thickness for obtaining the desired retardation is increased. Further, when the polyester base material is extruded into a sheet shape, stretching in the flow direction (machine direction), that is, longitudinal stretching may be performed. In this case, from the viewpoint of stably ensuring the value of the refractive index difference Δn within the above-described preferred range, the longitudinal stretching preferably has a stretching ratio of 2 times or less. Instead of longitudinal stretching during extrusion molding, longitudinal stretching may be performed after lateral stretching of the unstretched polyester is performed under the above conditions. Moreover, as processing temperature at the time of the said heat processing, 100-250 degreeC is preferable, More preferably, it is 180-245 degreeC.

  Examples of the method for controlling the retardation of the polyester substrate produced by the above-described method to 3000 nm or more include a method of appropriately setting the draw ratio, the drawing temperature, and the film thickness of the produced polyester substrate. Specifically, for example, the higher the stretching ratio, the lower the stretching temperature, and the thicker the film, the easier it is to obtain high retardation. The lower the stretching ratio, the higher the stretching temperature, and the film thickness. The thinner, the easier it is to obtain low retardation.

  Examples of the polycarbonate substrate include aromatic polycarbonate substrates based on bisphenols (bisphenol A and the like), aliphatic polycarbonate substrates such as diethylene glycol bisallyl carbonate, and the like.

  As a cycloolefin polymer base material, the base material which consists of polymers, such as a norbornene-type monomer and a monocyclic cycloolefin monomer, is mentioned, for example.

  The refractive index of the light transmissive substrate 11 can be 1.40 or more and 1.80 or less. In this case, the “refractive index of the light transmissive substrate” means an average refractive index.

  Further, the light transmissive substrate 11 may be subjected to a surface treatment such as a saponification treatment, a glow discharge treatment, a corona discharge treatment, an ultraviolet (UV) treatment, and a flame treatment without departing from the spirit of the present invention.

<Adhesion improvement layer>
As described above, the adhesion improving layer 13 is a layer for improving the adhesion between the light-transmitting substrate 11 and the antiglare layer 12, and can be composed of the same material as the known primer layer. It is. Specifically, the resin contained in the adhesion improving layer 13 is, for example, polyurethane resin, polyester resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer, acrylic resin, polyvinyl alcohol. Resin, polyvinyl acetal resin, copolymer of ethylene and vinyl acetate or acrylic acid, copolymer of ethylene and styrene and / or butadiene, thermoplastic resin such as olefin resin and / or modified resin thereof, light It can be composed of at least one of a polymer of a polymerizable compound and a thermosetting resin such as an epoxy resin.

  The photopolymerizable compound has at least one photopolymerizable functional group. In the present specification, the “photopolymerizable functional group” is a functional group capable of undergoing a polymerization reaction by light irradiation. Examples of the photopolymerizable functional group include ethylenic double bonds such as a (meth) acryloyl group, a vinyl group, and an allyl group. The “(meth) acryloyl group” means to include both “acryloyl group” and “methacryloyl group”. The light irradiated when polymerizing the photopolymerizable compound includes visible light and ionizing radiation such as ultraviolet rays, X-rays, electron beams, α rays, β rays, and γ rays.

  Examples of the photopolymerizable compound include a photopolymerizable monomer, a photopolymerizable oligomer, and a photopolymerizable polymer, and these can be appropriately adjusted and used. As the photopolymerizable compound, a combination of a photopolymerizable monomer and a photopolymerizable oligomer or photopolymerizable polymer is preferable.

  When the adhesion improving layer 13 is formed using a photopolymerizable compound, a polymerization initiator capable of initiating polymerization of the photopolymerizable compound is added to the adhesion improving layer 13. Is preferred. Thereby, when hardening the adhesive improvement layer 13, the adhesive improvement layer 13 and the glare-proof layer 12 can be bridge | crosslinked firmly.

  The thickness of the adhesion improving layer 13 can be 30 nm or more and 10 μm or less. When the thickness of the adhesion improving layer 13 is less than 30 nm, the uniformity of the adhesion improving layer 13 is lowered. The upper limit of the thickness of the adhesion improving layer 13 is not particularly set in terms of the function of the adhesion improving layer 13, but is preferably set to 1 μm or less for industrial reasons.

  In addition, the thickness (at the time of hardening) of the adhesive improvement layer 13 is measured values of arbitrary 10 points obtained by observing the cross section of the adhesive improvement layer 13 with an electron microscope (SEM, TEM, STEM), for example. As an average value (nm). When the adhesion improving layer 13 is very thin, it can be measured by recording what was observed at a high magnification as a photograph and further enlarging it. When enlarged, a layer interface line that is very thin enough to be clearly recognized as a boundary line becomes a thick line. In that case, what is necessary is just to measure the center part which divided the thick line width into 2 equally as a boundary line.

  The refractive index of the adhesion improving layer 13 can be 1.40 or more and 1.80 or less. The refractive index of the adhesion improving layer 13 can be measured by an Abbe refractometer (NAR-4T manufactured by Atago Co., Ltd.) or an ellipsometer after forming a single layer of the adhesion improving layer 13. In addition, as a method for measuring the refractive index after becoming an optical film, the cured film of each layer is scraped off with a cutter or the like to prepare a powder sample, and JISK7142 (2008) B method (for powder or granular transparent material) Becke method (using a Cargill reagent with a known refractive index, placing the powdered sample on a glass slide, dropping the reagent on the sample, and immersing the sample in the reagent. And a method in which the refractive index of the reagent is such that the bright line (Becke line) generated in the sample outline cannot be visually observed due to the difference in refractive index between the sample and the reagent.

  In addition, when the 2nd adhesive improvement layer 14 is provided in the optical film 10, it considers the adhesiveness with the other member joined to the optical film 10, and is carried out similarly to the adhesive improvement layer 13 mentioned above. Thus, the second adhesion improving layer 14 can be formed.

<Anti-glare layer>
The antiglare layer 12 has an uneven surface 12A as a surface on the side opposite to the light transmissive substrate 11 side (adhesion improving layer 13 side). The antiglare layer 12 imparts an antiglare function to the optical film 10 mainly due to the uneven surface 12A.

In the uneven surface 12A of the antiglare layer 12, the average interval Sm of the unevenness constituting the uneven surface 12A, the average inclination angle θa of the unevenness constituting the uneven surface 12A, the arithmetic average roughness Ra of the unevenness constituting the uneven surface 12A, and It is preferable that the ten-point average roughness Rz of the unevenness constituting the uneven surface 12A satisfies the following condition.
(Condition a1)
50 μm <Sm <600 μm
0.1 ° <θa <1.5 °
0.02 μm <Ra <0.25 μm
0.30 μm <Rz <2.00 μm
When the average interval Sm, the average inclination angle θa, the arithmetic average roughness Ra, and the ten-point average roughness Rz satisfy the above condition a1, only the edge portion of the captured image is sharpened while preventing excessive diffusion. By making it invisible, antiglare property can be secured. That is, when the condition a1 is satisfied, it is possible to avoid excessive diffusion and effectively prevent the generation of stray light, and to secure an appropriate amount of regular transmitted light. Thereby, the contrast in a bright room and a dark room can be improved effectively, providing the brightness of an image | video. Such characteristics are also referred to as blackness in this specification. On the other hand, if θa, Ra, and Rz are less than the lower limit of condition a1, reflection of external light may not be sufficiently suppressed. Also, if θa, Ra, Rz exceeds the upper limit of condition a1, the brightness of the image decreases due to the decrease in the regular transmission component, the bright room contrast decreases due to the increase in diffuse reflection of external light, and stray light from the transmitted image light The increase in the number can cause a problem that the dark room contrast decreases. In particular, when Sm exceeds the upper limit of the condition a1, there is a possibility that a problem that the fineness of the video cannot be reproduced occurs.

Moreover, in the uneven surface 12A of the antiglare layer 12, it is more preferable that the average interval Sm, the average inclination angle θa, the arithmetic average roughness Ra, and the ten-point average roughness Rz satisfy the following condition a2.
(Condition a2)
100 μm <Sm <400 μm
0.1 ° <θa <1.2 °
0.02 μm <Ra <0.15 μm
0.30 μm <Rz <1.20 μm
When the condition a2 is satisfied, reflection by external light can be more effectively prevented, and excellent blackness can be obtained.

In addition, in the uneven surface 12A of the antiglare layer 12, it is more preferable that the average interval Sm, the average inclination angle θa, the arithmetic average roughness Ra, and the ten-point average roughness Rz satisfy the following condition a3.
(Condition a3)
120 μm <Sm <300 μm
0.1 ° <θa <0.5 °
0.02 μm <Ra <0.12 μm
0.30 μm <Rz <0.80 μm
When the condition a3 is satisfied, reflection prevention due to external light and blackness in a state where the image display device is in black display are further improved.

Note that the definitions of “Sm”, “Ra”, and “Rz” conform to JIS B0601-1994. The definition of “θa” is in accordance with the surface roughness measuring instrument: SE-3400 / Kosaka Laboratory Co., Ltd. instruction manual (revised 1995.07.20). Specifically, as shown in FIG. 2, the heights h ₁ , h ₂ ,..., H _n existing within the reference length L are expressed by the following formula (2). .
θa = tan ⁻¹ {(h ₁ + h ₂ + h ₃ +... + h _n ) (2)

The average interval Sm, average inclination angle θa, arithmetic average roughness Ra, and ten-point average roughness Rz for the uneven surface 12A of the antiglare layer 12 are, for example, a surface roughness measuring instrument (model number: SE-3400 / Co., Ltd.). The value obtained by measurement under the following measurement conditions can be used.
1) Stylus of surface roughness detector (trade name SE2555N (2μ standard) manufactured by Kosaka Laboratory Ltd.)
・ Tip radius of curvature 2μm, apex angle 90 degrees, material diamond 2) Measurement conditions of surface roughness measuring instrument ・ Reference length (cutoff value λc of roughness curve): 2.5 mm
Evaluation length (reference length (cutoff value λc) × 5): 12.5 mm
・ Feeding speed of stylus: 0.5mm / s
・ Preliminary length: (cutoff value λc) × 2
・ Vertical magnification: 2000 times ・ Horizontal magnification: 10 times

  The antiglare layer 12 may be provided with some other function other than the antiglare property. As an example, functions such as hard coat properties, antistatic properties, and antifouling properties can be imparted. Here, the “hard coat property” is a layer for improving the scratch resistance of the optical film, and specifically, a pencil hardness test (4. JIS K5600-5-4 (1999)). It has a hardness of “H” or higher at 9N load).

  The thickness of the antiglare layer 12 is preferably 2.0 μm or more and 7.0 μm or less. If the thickness of the anti-glare layer 12 is within this range, when the anti-glare layer 12 has hard coat properties, the anti-glare layer 12 is provided with sufficient hardness while realizing the thinning of the anti-glare layer 12. Can do. By realizing a sufficient thinning of the antiglare layer 12, it is possible to suppress the occurrence of cracking and curling of the antiglare layer 12. In addition, the thickness of the glare-proof layer 12 can be measured by cross-sectional microscope observation. The lower limit of the thickness of the antiglare layer 12 is more preferably 3 μm or more, and the upper limit is more preferably 5 μm or less.

  The antiglare layer 12 having the uneven surface 12A is, for example, (1) applying a composition for an antiglare layer containing fine particles and a photopolymerizable compound to be a binder resin after polymerization to a light transmissive substrate or an adhesion improving layer. Method, (2) Applying composition for anti-glare layer to light-transmitting substrate or adhesion improving layer, and then embossing mold having anti-concave groove on the surface into anti-glare layer composition Method, or (3) A composition for an antiglare layer in which disk-shaped particles having a concavo-convex shape corresponding to a concavo-convex surface are dispersed is applied to a light-transmitting substrate or an adhesion improving layer, and the disk-shaped particles Can be formed by, for example, a method of arranging the layers on the surface of the antiglare layer. Among these, the method (1) is preferable because of easy production.

  In the above method (1), when the photopolymerizable compound is polymerized (crosslinked) to become a binder resin, the photopolymerizable compound undergoes curing shrinkage in the portion where fine particles are not present, and thus shrinks as a whole. To do. On the other hand, in the portion where the fine particles are present, since the fine particles do not cause curing shrinkage, only the photopolymerizable compounds existing above and below the fine particles cause curing shrinkage. Thereby, since the film thickness of the anti-glare layer is thicker in the part where the fine particles are present than in the part where the fine particles are not present, the surface of the anti-glare layer becomes uneven. Therefore, an antiglare layer having an uneven surface can be formed by appropriately selecting the type and particle size of the fine particles and the type of the photopolymerizable compound and adjusting the coating film forming conditions.

  The antiglare layer 12 shown in FIG. 3 is an example of an antiglare layer produced by the method (1). In particular, the antiglare layer 12 includes both organic fine particles 12c and inorganic fine particles 12d as fine particles dispersed in the binder resin 12b. And the anti-glare layer 12 originates in distribution in the anti-glare layer 12 of the organic fine particle 12c and the inorganic fine particle 12d, and the case where the uneven | corrugated shape of the anti-glare layer surface is formed with a single fine particle (for example, organic fine particle) In comparison, it has a smoother uneven shape. As a result, in the antiglare layer 12 shown in FIG. 3, the above-described condition a3 regarding “Sm”, “θa”, “Ra”, and “Rz” is satisfied, and the antiglare property and the hard coat property are maintained. The film can be made thin, and the generation of surface glare can be sufficiently suppressed to achieve excellent blackness.

  Hereinafter, as an example of the antiglare layer 12, the antiglare layer shown in FIG.

  The antiglare layer 12 shown in FIG. 3 has a binder resin 12b, and organic fine particles 12c and inorganic fine particles 12d dispersed in the binder resin 12b. Most of the inorganic fine particles 12d are dispersed in the binder resin 12b as aggregates. As shown in FIG. 3, the inorganic fine particles 12d are distributed roughly in the binder resin 12b. In other words, the inorganic fine particles 12d are unevenly distributed in the binder resin 12b.

  In addition, the inorganic fine particles 12d are “distributed densely” in the anti-glare layer 12 is a region where the inorganic fine particles 12d are densely distributed (region where a large number of inorganic fine particles are present) and an inorganic material. This means that there are a plurality of regions in which the fine particles 12d are roughly distributed (regions in which almost no inorganic fine particles are present). More specifically, the normal direction of the anti-glare layer in a region where the aggregates of the inorganic fine particles 12d are densely distributed (electron microscope (transmission type such as TEM, STEM, etc. is preferable) at a magnification of 10,000 times. When an arbitrary cross section is observed, the area ratio of the aggregates of inorganic fine particles in the observation area of 2 μm square is 5% or more) and the area where the inorganic fine particles are roughly distributed (electron microscope (TEM) In addition, when an arbitrary cross section in the normal direction of the antiglare layer is observed under the condition of 10,000 times magnification under the condition of a transmission type such as STEM), the area ratio of the inorganic fine particles in the observation area of 2 μm square is 1%. A region that is less than or equal to). That is, the inorganic fine particles 12d are non-uniformly dispersed in the binder resin 12b.

  Whether or not such inorganic fine particles 12d are densely distributed can be easily determined by using an electron microscope observation in a cross section along the normal direction of the antiglare layer 12. In the cross section of the antiglare layer 12 shown in FIG. 3, the portions observed in black spots are the inorganic fine particles 12 d existing as aggregates. From the photograph in FIG. 3, it can be clearly confirmed that the inorganic fine particles 12 d are dispersed non-uniformly in the antiglare layer 12. The area ratio of the inorganic fine particles 12d can be calculated using, for example, image analysis software.

  As described above, in the antiglare layer 12 shown in FIG. 3, the aggregates of the inorganic fine particles 12d are distributed roughly in the binder resin 12b. As shown in FIG. 3, a part of the inorganic fine particles 12d is densely distributed around the organic fine particles 12c. That is, as shown in FIG. 3, a part of the aggregate of the inorganic fine particles 12d is densely present around the organic fine particles 12c, and the other part of the aggregate of the inorganic fine particles 12d is other than the periphery of the organic fine particles 12c. It is densely present in the area. As shown in FIG. 3, the state in which the aggregates of the inorganic fine particles 12d are densely distributed around the organic fine particles 12c can be easily confirmed by observing the cross section of the antiglare layer 12 with an electron microscope. According to the electron microscope observation of the cross section of the antiglare layer 12, the aggregate of the inorganic fine particles 12c densely distributed around the organic fine particles 12 is not only the cross section passing through the center of the organic fine particles 12c but also the center of the organic fine particles 12c. Even in the cross section deviated from, it is densely distributed.

  Note that “the inorganic fine particles are densely distributed around the organic fine particles” means that the normal direction of the antiglare layer is 20,000 times with an electron microscope (transmission type such as TEM or STEM is preferable). When the cross section along the line is observed, the area ratio of the inorganic fine particles 12d in the circumferential region surrounding the organic fine particles 12c within the range of 200 nm from the outer periphery of the observed organic fine particles is 10% or more. means. The area ratio of the inorganic fine particles 12d can be calculated using, for example, image analysis software.

  In the antiglare layer 12, the aggregates of the inorganic fine particles 12d densely distributed around the organic fine particles 12c are attached to the surface of the organic fine particles 12c and / or impregnated in the organic fine particles 12c (hereinafter referred to as the following). It is preferable that the aggregate of the inorganic fine particles 12d is also attached to the surface of the organic fine particles 12c). Since the aggregate of the inorganic fine particles 12d adheres to the surface of the organic fine particles 12c, a cohesive force acts between the inorganic fine particles 12d attached to the surfaces of the different organic fine particles 12c. Using this cohesive force, different organic fine particles 12c can be collected. For this reason, even if there is little addition amount of the organic fine particle 12c, the uneven | corrugated shape which has sufficient anti-glare property can be formed. The collection of the organic fine particles 12c means that the organic fine particles 12c are not completely in close contact with each other, but the distance between the organic fine particles 12c closest to the cross-sectional observation of the antiglare layer is the average of the particles. It means a case where the particle diameter is smaller than the particle diameter, or a case where a plurality of aggregates of the inorganic fine particles 12d are continuously connected between the organic fine particles. Aggregates of the inorganic fine particles 12d adhered to the surface of the organic fine particles 12c can be easily confirmed by observing the cross section of the antiglare layer 12 with an electron microscope.

  An example of a method for attaching the aggregate of the inorganic fine particles 12d to the surface of the organic fine particles 12c is a method of hydrophilizing the surface of the organic fine particles 12c. Moreover, as a method of impregnating a part of the inorganic fine particles 12d constituting the aggregate of the inorganic fine particles 12d from the surface to the inside of the organic fine particles 12c, for example, when forming the antiglare layer 12, the organic fine particles 12c Examples thereof include a method for lowering the degree of crosslinking and a method for using a solvent capable of swelling the organic fine particles 12c in the composition for an antiglare layer.

  It is preferable that the organic fine particles 12c have adhesion of aggregates of the inorganic fine particles 12d more uniformly on almost the entire surface thereof. The ratio of the aggregates of the inorganic fine particles 12d adhering to the surface of the organic fine particles 12c to the aggregates of the inorganic fine particles 12d densely distributed around the organic fine particles 12c is the transmission type such as an electron microscope (TEM, STEM, etc.). Is preferable) when the cross section along the normal direction of the antiglare layer is observed under the condition of magnification of 20,000 times, the circumference surrounding the organic fine particles 12c within the range of 200 nm from the outer circumference of the organic fine particles to be observed Of the aggregates of the inorganic fine particles in the region, the area ratio is preferably 50% or more. When it is 50% or more, the effect of collecting the organic fine particles in the antiglare layer is sufficiently exerted, and the unevenness exhibiting sufficient antiglare performance can be stably formed on the uneven surface 12A.

  When a part of the inorganic fine particles 12d constituting the aggregate of the inorganic fine particles 12d is impregnated on the surface of the organic fine particles 12c, the aggregate of the inorganic fine particles 12d is within a depth of 500 nm from the surface of the organic fine particles 12c. It is preferable to impregnate. When the impregnation of the inorganic fine particles 12d into the organic fine particles 12c does not exceed 500 nm, the above-described gentle uneven shape, that is, the thin film can be formed while maintaining the antiglare property, and the generation of surface glare and blurring can be achieved. The uneven shape that can sufficiently suppress the occurrence can be formed on the uneven surface 12A of the antiglare layer 12. Further, when the impregnation of the organic fine particles 12c with the inorganic fine particles 12d does not exceed 500 nm, it is not necessary to swell the organic fine particles 12c excessively, and the viscosity of the composition for the antiglare layer for forming the antiglare layer 12 is sufficient. The thickness of the coating film of the composition for an antiglare layer applied on the light transmissive substrate 11 or the adhesion improving layer 13 can be effectively made uniform.

  In the antiglare layer 12 shown in FIG. 3, the binder resin 12b contains aggregates of organic fine particles 12d and organic fine particles 12c in a specific state as described above. As a result, the antiglare layer 12 in the obtained optical film 10 has a smoother shape with a gentler slope of the convex portion than the concave and convex shape formed by a single fine particle or an aggregate thereof. As a result, the optical film 10 can improve the contrast while maintaining the antiglare property. Since the slope of the convex portion of the uneven surface 12A becomes gentle and has a smooth shape, the antiglare layer 12 functions so that only the edge portion of the image reflected on the surface of the antiglare layer 12 is not clearly visible. Furthermore, according to the anti-glare layer 12 having such an uneven surface 12A, large diffusion can be eliminated, so that the generation of stray light can be effectively prevented. In addition, since the amount of light that is transmitted normally can be appropriately secured, the image can be given shine, and the contrast in the bright room and the dark room can be greatly improved.

  Next, an example of a method for producing the antiglare layer shown in FIG. 3 will be described. In the following, a composition for an antiglare layer containing fine particles and a photopolymerizable compound that becomes a binder resin after polymerization is applied to an adhesion improving layer on a light-transmitting substrate, and then the coating film is cured and adhered. An antiglare layer is formed on the property improving layer.

  In particular, in the method described below, the composition for an antiglare layer contains a predetermined amount of a solvent having a high polarity and a high volatilization rate together with a photopolymerizable compound that forms inorganic fine particles, organic fine particles, and a binder resin. Yes. As a result of extensive research conducted by the present inventors, when such an antiglare layer composition is used, organic fine particles and inorganic fine particles are dispersed in the binder resin in the above-described manner, resulting in antiglare properties. It has been found that an uneven surface can be formed on the anti-glare layer 12 that can be thinned while being maintained, and that can sufficiently suppress generation of surface glare and have excellent blackness.

In the following explanation, first, each component contained in the composition for the antiglare layer will be described, then, a method for adjusting the composition for the antiglare layer will be described, and then the composition for the antiglare layer will be used. A method for producing the antiglare layer will be described. The inorganic fine particles contained in the antiglare layer include various known fine particles such as silica (SiO ₂ ) fine particles, alumina fine particles, titania fine particles, tin oxide fine particles, antimony-doped tin oxide (abbreviation: ATO) fine particles, and zinc oxide fine particles. Although fine particles can be used, in the following specific example, an example in which silica (SiO ₂ ) fine particles are used as the inorganic fine particles contained in the antiglare layer will be described.

  First, the solvent contained in the antiglare layer composition will be described.

  The composition for an antiglare layer contains a solvent having a high polarity and a high volatilization rate. According to the solvent having a high polarity and a high volatilization rate, it is possible to prevent the silica fine particles from being excessively aggregated in the composition for the antiglare layer. On the other hand, when the antiglare layer composition is applied onto the light-transmitting substrate or the adhesion improving layer to form a coating film, and then the coating film is dried, the polarity is high and the volatilization occurs. A fast solvent will volatilize before other solvents. As a result, the composition in the coating film is modified, and as a result, aggregates of silica fine particles gather around the organic fine particles in the coating film, and the silica fine particles are formed in regions other than the periphery of the organic fine particles in the coating film. Aggregates also gather together. As a result, in the coating film, it is possible to form a state where the aggregates of silica fine particles are dense and densely distributed around the organic fine particles.

  The solvent having a high polarity and a high volatilization rate is 20% by mass or more of the total solvent contained in the composition for the antiglare layer. If it is less than 20% by mass, an aggregate of silica fine particles is produced in the composition for the antiglare layer. As a result, a desired uneven shape cannot be formed on the surface of the antiglare layer, and precipitation due to aggregation of fine particles may occur in the composition for the antiglare layer. The solvent having a high polarity and a high volatilization rate is preferably 50% by mass or less based on the total amount of the solvent contained in the antiglare layer composition. If the content exceeds 50% by mass, a solvent having a high polarity and a high volatilization rate tends to remain when the coating film is dried, so that silica fine particles and organic fine particles are preferably distributed in the coating film. May not be possible.

In the present specification, “a solvent having a high polarity” means a solvent having a solubility parameter of 10 [(cal / cm ³ ) ^1/2 ] or more, and “a solvent having a high volatilization rate” means relative evaporation. It means a solvent having a speed of 150 or more. Therefore, the “solvent having a high polarity and a high volatilization rate” means a solvent satisfying the requirements of both the “solvent having a high polarity” and the “solvent having a high volatilization rate”. In the present specification, the solubility parameter is calculated by the method of Fedors. The Fedors method is described, for example, in “SP Value Basics / Applications and Calculation Methods” (Hideki Yamamoto, published by Information Technology Corporation, 2005). In the Fedors method, the solubility parameter is calculated by the following equation (3).
Solubility parameter = [ΣE _coh / ΣV] ² (3)
In the above formula (3), _Ecoh is the cohesive energy density, and V is the molar molecular volume. Based on E _coh and V determined for each atomic group, the solubility parameter can be calculated by obtaining Σ _Ecoh and ΣV, which is the sum of E _coh and V. Moreover, in this specification, the said relative evaporation rate means a relative evaporation rate when the evaporation rate of n-butyl acetate is set to 100, and is an evaporation rate measured in accordance with ASTM D3539-87. Calculated by equation (4). Specifically, the evaporation time of n-butyl acetate and the evaporation time of each solvent in dry air at 25 ° C. are measured and calculated.
Relative evaporation rate =
(Time required for 90% by weight of n-butyl acetate to evaporate) /
(Time required for 90% by weight of measurement solvent to evaporate) × 100 (4)

  Preferable examples of the solvent having a high polarity and a high volatilization rate include ethanol and isopropyl alcohol. Of these, isopropyl alcohol is more preferably used.

  Other solvents contained in the antiglare layer composition include, for example, ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, etc.) , Alicyclic hydrocarbons (cyclohexane, etc.), aromatic hydrocarbons (toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), alcohol (Butanol, cyclohexanol, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates, sulfoxides (dimethylsulfoxide, etc.), amides (dimethylformamide, dimethylacetamide, etc.), etc., and mixtures thereof So It may be.

  Next, silica fine particles as inorganic fine particles will be described.

  In the composition for an antiglare layer, the silica fine particles may form an aggregate described later, but are preferably dispersed uniformly. When the coating film formed by applying the composition for the antiglare layer is dried, it is preferable that the silica fine particle distribution in the coating film is coarse and dense, and is densely distributed around the organic fine particles. If the aggregate of the silica fine particles is not uniformly dispersed in the composition for the antiglare layer, the aggregation of the silica fine particles proceeds excessively in the composition for the antiglare layer. When the aggregation proceeds excessively, a huge aggregate of silica fine particles is generated, and it becomes impossible to form an antiglare layer having a desired smooth uneven shape.

  Silica fine particles can thicken the composition for an antiglare layer. For this reason, sedimentation of the organic fine particles contained in the composition for the antiglare layer can be suppressed by containing the silica fine particles. That is, it is presumed that the silica fine particles have a function of promoting the formation of a predetermined distribution of the organic fine particles and the aggregates of the silica fine particles in the antiglare layer and a function of improving the pot life of the composition for the antiglare layer.

  The silica fine particles are preferably surface-treated. When the silica fine particles are surface-treated, the degree of coarse distribution of the silica fine particles in the antiglare layer can be suitably controlled. In addition, when the silica fine particles are surface-treated, the effect of gathering around the organic fine particles can be controlled within an appropriate range. Further, the chemical resistance and saponification resistance of the silica fine particles themselves can be improved.

  Examples of the surface treatment of the silica fine particles include a method of treating the silica fine particles with a silane coupling agent having octylsilane. Here, normally, hydroxyl groups are present on the surface of the silica fine particles, but the surface treatment reduces the hydroxyl groups on the surface of the silica fine particles, thereby reducing the specific surface area of the silica fine particles. As a result, the silica fine particles can be prevented from agglomerating excessively, and the above-described effects are exhibited.

  The silica fine particles are preferably made of amorphous silica. When the silica fine particles are made of crystalline silica, the lattice defects contained in the crystal structure may increase the Lewis acidity of the silica fine particles, making it impossible to control excessive aggregation of the silica fine particles described above.

  As described above, in the composition for an antiglare layer, the silica fine particles may form an aggregate, but are preferably dispersed uniformly. On the other hand, when the antiglare layer is formed, the aggregates of the silica fine particles are preferably distributed densely and further densely distributed around the organic fine particles. If the aggregate of the silica fine particles is not uniformly dispersed in the composition for the antiglare layer, the aggregation of the silica fine particles proceeds excessively in the composition for the antiglare layer. This is because, when the aggregation proceeds excessively, a huge aggregate of silica fine particles is generated, and an antiglare layer having a desired smooth uneven shape cannot be formed. As already described, the concavo-convex shape formed on the concavo-convex surface of the antiglare layer is a single fine particle because the aggregate of silica fine particles is contained in the specific distribution state described above in the antiglare layer. Compared to the uneven shape formed on the surface of the antiglare layer by an aggregate (for example, organic fine particles, etc.) or an aggregate of single particles (for example, an aggregate of silica fine particles), the convex portion has a gentle slope and a smooth shape. It becomes.

As such silica fine particles, fumed silica is preferably used, for example, because it itself tends to aggregate and easily form aggregates. Fumed silica is amorphous silica having a particle size of 200 nm or less prepared by a dry method, and can be obtained by reacting a volatile compound containing silicon in a gas phase. Specific examples include those produced by hydrolyzing a silicon compound such as silicon tetrachloride (SiCl ₄ ) in a flame of oxygen and hydrogen. Examples of commercially available fumed silica fine particles include AEROSIL R805 manufactured by Nippon Aerosil Co., Ltd.

  Although the fumed silica fine particles form aggregates, the aggregates of the fumed silica fine particles are not dense aggregates in the composition for an antiglare layer, and are sufficiently sparse such as cocoon-like or string-like. Some agglomerates are formed. For this reason, the agglomerates of fumed silica fine particles are easily and uniformly crushed when the photopolymerizable compound which becomes the binder resin after curing undergoes curing shrinkage. Thereby, desired uneven | corrugated shape can be provided to an uneven surface.

  Although it does not specifically limit as content of a silica particle, It is preferable that it is the quantity used as 0.1-5.0 mass% in the anti-glare layer formed. When the content of the silica fine particles is 0.1% by mass or more, a dense distribution can be sufficiently formed around the organic fine particles. When the content of silica fine particles exceeds 5.0 mass%, the problem of white blur may occur. A more preferable lower limit is 0.5% by mass, and a more preferable upper limit is 3.0% by mass.

  The silica fine particles preferably have an average primary particle diameter of 1 to 100 nm. If it is less than 1 nm, a dense distribution may not be sufficiently formed around the organic fine particles, and if it exceeds 100 nm, a dense distribution may not be sufficiently formed around the organic fine particles. A more preferred lower limit is 5 nm, and a more preferred upper limit is 50 nm. The average primary particle diameter of the silica fine particles is a value measured using an image processing software from an image of a cross-sectional electron microscope (TEM, STEM, etc., and preferably a magnification of 50,000 times or more). .

  Moreover, the aggregate of silica fine particles forms a structure in which the above-described silica fine particles are arranged in a bead shape in the antiglare layer to be formed. By forming an aggregate in which the silica fine particles are arranged in a bead shape in the antiglare layer, the surface uneven shape of the antiglare layer can be suitably made smooth. The structure in which the silica fine particles are connected in a bead shape is, for example, a structure in which silica fine particles are continuously connected in a straight line (linear structure), a structure in which a plurality of the linear structures are intertwined, or a silica in a linear structure. Any structure such as a branched structure having one or more side chains in which a plurality of fine particles are continuously formed can be mentioned.

  The aggregate of silica fine particles preferably has an average particle diameter of 100 nm to 1 μm. If the thickness is less than 100 nm, a dense distribution may not be sufficiently formed around the organic fine particles, and if it exceeds 1 μm, a dense distribution may not be sufficiently formed around the organic fine particles. Light is diffused by the aggregate, and the dark room contrast of the image display device using the manufactured optical film may be inferior. The more preferable lower limit of the average particle diameter of the aggregate is 200 nm, and the more preferable upper limit is 800 nm. The average particle size of the aggregates of silica fine particles was selected from a 5 μm square region containing a large amount of aggregates of silica fine particles based on observation of the antiglare layer by a cross-sectional electron microscope (about 10,000 to 20,000 times). The particle diameters of the aggregates of silica fine particles in the region are measured, and the particle diameters of the aggregates of the top 10 silica fine particles are averaged. The “particle diameter of the aggregate of silica fine particles” is 2 so that the distance between the two straight lines becomes maximum when the cross section of the silica fine particle aggregate is sandwiched between any two parallel straight lines. It is measured as the distance between straight lines in a combination of straight lines. Further, the particle diameter of such an aggregate of silica fine particles may be calculated using image analysis software.

  Next, the organic fine particles contained in the antiglare layer composition will be described.

  The organic fine particles mainly form an uneven shape on the uneven surface of the antiglare layer to be formed. The organic fine particles are preferably fine particles having a relatively uniform particle diameter. In addition, it is preferable that the silica fine particles form an aggregate in the antiglare layer as described above, and are distributed coarsely. In the antiglare layer, the silica particle is an aggregate having a relatively large variation in particle diameter. It is preferable. The anti-glare layer formed by using the anti-glare layer composition contains organic fine particles having a uniform particle size because the anti-glare layer composition contains two kinds of fine particles having such a particle size relationship. Therefore, it is easy to form a structure in which silica fine particles having a large variation in particle diameter are included, and the above-described smooth uneven shape can be suitably formed on the uneven surface of the antiglare layer.

  Here, with respect to organic fine particles, “fine particles having a relatively uniform particle size” means that when the average particle size by weight average is MV, the cumulative 25% diameter is d25, and the cumulative 75% diameter is d75 (d75− d25) It means the case where / MV is 0.25 or less. In addition, regarding the organic fine particles, “particles having a relatively large variation in particle diameter” means that the above (d75−d25) / MV exceeds 0.25. Here, the cumulative 25% diameter refers to the particle diameter when counted from particles having a small particle diameter in the particle size distribution and reaches 25% by mass, and the cumulative 75% diameter is similarly counted to 75. The particle diameter when it becomes mass%. The average particle diameter, the cumulative 25% diameter and the cumulative 75% diameter of the fine particles by weight average can be measured as the weight average diameter by the Coulter counter method.

  The organic fine particles and silica fine particles are preferably spherical in shape in a single particle state. Since the organic fine particles and the single particles of the silica fine particles are spherical, a high-contrast display image can be obtained when an optical film including an antiglare layer is applied to an image display device. In addition, the above “spherical” includes, for example, a true spherical shape, an elliptical spherical shape and the like, and has a meaning excluding so-called indefinite shape.

  The organic fine particles are fine particles that mainly form the surface unevenness shape of the antiglare layer, and are fine particles whose refractive index and particle size can be easily controlled. By including such organic fine particles, it becomes easy to control the size of the uneven shape of the uneven surface formed in the antiglare layer and the refractive index of the antiglare layer, and control of antiglare properties and generation of surface glare and white blurring Can be suppressed.

  The organic fine particles are fine particles made of at least one material selected from the group consisting of acrylic resin, polystyrene resin, styrene-acrylic copolymer resin, polyethylene resin, epoxy resin, silicone resin, polyvinylidene fluoride resin, and polyfluorinated ethylene resin. It is preferable that Of these, styrene-acrylic copolymer fine particles are preferably used as the organic fine particles.

  The organic fine particles are preferably subjected to a surface hydrophilization treatment. Since the organic fine particles are subjected to a surface hydrophilization treatment, the affinity with the silica fine particles is increased. Thereby, silica fine particles are easily distributed around the organic fine particles in the formed antiglare layer. The hydrophilic treatment of the organic fine particles is not particularly limited, and a known method can be adopted. For example, a method of copolymerizing a monomer having a functional group such as a carboxylic acid group or a hydroxyl group on the surface of the organic fine particles can be employed.

  Normally, the organic fine particles subjected to the surface hydrophilization treatment cannot be gently gathered in the antiglare layer, so that a sufficient uneven shape cannot be formed on the surface of the antiglare layer and the antiglare performance is inferior. It will be. However, in the antiglare layer shown in FIG. 3, the silica fine particles form aggregates and are contained densely in the antiglare layer, and the silica fine particle aggregates are densely distributed around the organic fine particles. . For this reason, in the antiglare layer, the arrangement of the organic fine particles subjected to the surface hydrophilization treatment is controlled, and the uneven surface of the antiglare layer can be formed into a desired uneven shape.

  The content of the organic fine particles is preferably an amount of 0.5 to 10.0% by mass in the formed antiglare layer. When the content of the organic fine particles is less than 0.5% by mass, the antiglare performance of the formed antiglare layer may be insufficient. When the content of the organic fine particles exceeds 10.0% by mass, a problem of white blurring may occur in the formed antiglare layer. Also, when the manufactured optical film is used in an image display device, a display image is displayed. The contrast may be inferior. The more preferable lower limit of the content of the organic fine particles in the antiglare layer is 1.0% by mass, and the more preferable upper limit of the content of the organic fine particles in the antiglare layer is 8.0% by mass.

  Moreover, although the magnitude | size of organic fine particle is suitably determined according to the thickness etc. of the glare-proof layer formed, it is preferable that an average particle diameter is 0.3-5.0 micrometers, for example. If the average particle size of the organic fine particles is less than 0.3 μm, the dispersibility of the organic fine particles may not be controlled. When the average particle diameter of the organic fine particles exceeds 5.0 μm, the uneven shape on the surface of the antiglare layer to be formed becomes large, which may cause a problem of surface glare. A more preferable lower limit of the average particle diameter of the organic fine particles is 1.0 μm, and a more preferable upper limit of the average particle diameter of the organic fine particles is 3.0 μm. Moreover, it is preferable that the average particle diameter of organic fine particles is 20 to 60% with respect to the thickness of the anti-glare layer formed. If the ratio of the average particle diameter of the organic fine particles to the thickness of the antiglare layer exceeds 60%, the organic fine particles may protrude to the outermost surface of the antiglare layer, and the unevenness caused by the organic fine particles may be sharp. There is. When the ratio of the average particle diameter of the organic fine particles to the thickness of the antiglare layer is less than 20%, a sufficient uneven shape cannot be formed on the surface of the antiglare layer, and the antiglare performance of the formed antiglare layer is not good. May be sufficient.

  The average particle diameter of the organic fine particles can be measured as a weight average diameter by a Coulter counter method when the organic fine particles are measured alone. On the other hand, the average particle diameter of the organic fine particles in the formed antiglare layer is obtained as an average value of the maximum diameters of 10 particles in the transmission optical microscope observation of the antiglare layer. Alternatively, if it is not suitable, the diffusing particles 30 that are observed as an almost the same particle size of the same kind in the electron microscope (transmission type such as TEM, STEM, etc.) observation of the cross section passing through the vicinity of the particle center. This is a value calculated as an average value by selecting the individual particles (increasing the number of n because it is unknown which part of the particle is a cross section) and measuring the maximum particle diameter of the cross section. Since both are determined from the image, the image may be calculated by image analysis software.

  Next, the photopolymerizable compound contained in the antiglare layer composition will be described.

  The binder resin is obtained by polymerizing (crosslinking) a photopolymerizable compound by light irradiation. For this reason, the composition for anti-glare layers contains a photopolymerizable compound. The photopolymerizable compound has at least one photopolymerizable functional group. The definition of “photopolymerizable functional group” is the same as described in the column of the adhesion improving layer 13.

  Examples of the photopolymerizable compound include a photopolymerizable monomer, a photopolymerizable oligomer, and a photopolymerizable polymer, and these can be appropriately adjusted and used. As the photopolymerizable compound, a combination of a photopolymerizable monomer and a photopolymerizable oligomer or photopolymerizable polymer is preferable.

  The photopolymerizable monomer has a weight average molecular weight of less than 1000. The photopolymerizable monomer is preferably a polyfunctional monomer having two or more photopolymerizable functional groups (that is, bifunctional). In the present specification, the “weight average molecular weight” is a value obtained by dissolving in a solvent such as THF and converting to polystyrene by a conventionally known gel permeation chromatography (GPC) method. The photopolymerizable oligomer has a weight average molecular weight of more than 1000 and 10,000 or less. The photopolymerizable oligomer is preferably a bifunctional or higher polyfunctional oligomer. The photopolymerizable polymer has a weight average molecular weight exceeding 10,000, and the weight average molecular weight is preferably 10,000 or more and 80,000 or less, and more preferably 10,000 or more and 40,000 or less. When the weight average molecular weight exceeds 80,000, the viscosity is high, so that the coating suitability is lowered, and the appearance of the obtained optical laminate may be deteriorated.

  As the photopolymerizable monomer, a polyfunctional acrylate monomer having no hydroxyl group in the molecule is preferably used as a main material. The phrase “mainly composed of a polyfunctional acrylate monomer having no hydroxyl group in the molecule” means that the content of the polyfunctional acrylate monomer having no hydroxyl group in the molecule is the largest in the photopolymerizable monomer. Since the polyfunctional acrylate monomer containing no hydroxyl group in the molecule is a hydrophobic monomer, the binder resin contained in the antiglare layer formed using the composition for antiglare layer is preferably a hydrophobic resin. . When the binder resin is mainly composed of a hydrophilic resin having a hydroxyl group, the above-mentioned highly polar solvent (for example, isopropyl alcohol) is difficult to evaporate, and silica fine particles are difficult to adhere to and / or impregnate organic fine particles. In this case, agglomeration proceeds only with the silica fine particles, and there is a risk of forming convex portions on the surface of the anti-glare layer that worsen surface glare.

  Examples of the polyfunctional acrylate monomer having no hydroxyl group in the molecule include pentaerythritol tetraacrylate (PETTA), 1,6-hexanediol diacrylate (HDDA), dipropylene glycol diacrylate (DPGDA), and tripropylene glycol diacrylate. (TPGDA), PO-modified neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate (TMPTA), trimethylolpropane ethoxytriacrylate, dipentaerythritol hexaacrylate (DPHA), pentaerythritol ethoxytetraacrylate , Ditrimethylolpropane tetraacrylate and the like. Of these, dipentaerythritol hexaacrylate (DPHA) and pentaerythritol tetraacrylate (PETTA) are preferably used.

  The other photopolymerizable monomer that may be contained in the antiglare layer composition is preferably a transparent monomer. For example, an ionizing radiation curable resin that is cured by ultraviolet rays or electron beams is ultraviolet rays or electron beams. It is preferable that it is hardened | cured by irradiation. In the present specification, “resin” is a concept including monomers, oligomers and the like unless otherwise specified.

  Examples of the ionizing radiation curable resin include compounds having one or more unsaturated bonds such as compounds having an acrylate functional group. Examples of the compound having one unsaturated bond include ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N-vinylpyrrolidone and the like. Examples of the compound having two or more unsaturated bonds include trimethylolpropane tri (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipentaerythritol. Hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) ) Acrylate, dipentaerythritol penta (meth) acrylate, tripentaerythritol octa (meth) acrylate, tetrapentaerythritol deca (meta Acrylate, isocyanuric acid tri (meth) acrylate, isocyanuric acid di (meth) acrylate, polyester tri (meth) acrylate, polyester di (meth) acrylate, bisphenol di (meth) acrylate, diglycerin tetra (meth) acrylate, adamantyl di ( Examples include polyfunctional compounds such as (meth) acrylate, isobornyl di (meth) acrylate, dicyclopentane di (meth) acrylate, and tricyclodecane di (meth) acrylate. In the present specification, “(meth) acrylate” refers to methacrylate and acrylate. In the present invention, as the ionizing radiation curable resin, a compound obtained by modifying the above-described compound with PO, EO or the like can also be used.

  In addition to the above compounds, relatively low molecular weight polyester resins having unsaturated double bonds, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. It can be used as an ionizing radiation curable resin.

  The ionizing radiation curable resin should be used in combination with a solvent-drying resin (such as a thermoplastic resin that can be used as a coating only by drying the solvent added to adjust the solid content during coating). You can also. By using the solvent-drying resin in combination, film defects on the coating surface of the coating liquid can be effectively prevented when the antiglare layer is formed. The solvent dry resin that can be used in combination with the ionizing radiation curable resin is not particularly limited, and a thermoplastic resin can be generally used. The thermoplastic resin is not particularly limited. For example, styrene resin, (meth) acrylic resin, vinyl acetate resin, vinyl ether resin, halogen-containing resin, alicyclic olefin resin, polycarbonate resin, polyester resin Polyamide resins, cellulose derivatives, silicone resins and rubber or elastomers can be used. The thermoplastic resin is preferably amorphous and soluble in an organic solvent (particularly a common solvent capable of dissolving a plurality of polymers and curable compounds). In particular, from the viewpoints of film forming properties, transparency and weather resistance, styrene resins, (meth) acrylic resins, alicyclic olefin resins, polyester resins, cellulose derivatives (cellulose esters, etc.) and the like are preferable.

  Moreover, the composition for anti-glare layers may contain a thermosetting resin. The thermosetting resin is not particularly limited. For example, phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, melamine-urea cocondensation resin Silicon resin, polysiloxane resin, or the like can be used.

  It is preferable that the composition for anti-glare layers further contains a photopolymerization initiator. The photopolymerization initiator is not particularly limited, and known ones can be used. Specific examples include, for example, acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime esters, thioxanthones, propiophenones. , Benzyls, benzoins, acylphosphine oxides. In addition, it is preferable to use a mixture of photosensitizers, and specific examples thereof include n-butylamine, triethylamine, poly-n-butylphosphine, and the like.

  As the photopolymerization initiator, in the case where the photopolymerizable monomer component of the photopolymerizable compound forming the binder resin is a resin system having a radical polymerizable unsaturated group, acetophenones, benzophenones, thioxanthones, benzoin, benzoin methyl Ether or the like is preferably used alone or in combination. When the monomer component of the binder resin is a resin system having a cationic polymerizable functional group, the photopolymerization initiator may be an aromatic diazonium salt, aromatic sulfonium salt, aromatic iodonium salt, metallocene compound, benzoin sulfonate ester. Etc. are preferably used alone or as a mixture.

  It is preferable that content of the said photoinitiator in the composition for glare-proof layers is 0.5-10.0 mass parts with respect to 100 mass parts of monomer components of the photopolymerizable compound which a binder resin makes. If it is less than 0.5 part by mass, the hard coat performance of the antiglare layer to be formed may be insufficient, and if it exceeds 10.0 parts by mass, there is also a possibility of inhibiting curing. It is not preferable.

  Although it does not specifically limit as a content rate (solid content) of the raw material in the composition for glare-proof layers, Usually, it is preferable to set it as 5-70 mass%, especially 25-60 mass%.

  The antiglare layer composition includes conventionally known dispersants, surfactants, antistatic agents, silanes depending on purposes such as increasing the hardness of the antiglare layer, suppressing cure shrinkage, and controlling the refractive index. Coupling agent, thickener, anti-coloring agent, coloring agent (pigment, dye), antifoaming agent, leveling agent, flame retardant, UV absorber, adhesion-imparting agent, polymerization inhibitor, antioxidant, surface modifier Further, an easy lubricant or the like may be added. Examples of the leveling agent include silicone oils, fluorine-based surfactants, and the like, preferably fluorine-based surfactants containing a perfluoroalkyl group, and the formed antiglare layer has a Benard cell structure. It is preferable because of avoidance. When a resin composition containing a solvent is applied and dried, a surface tension difference or the like is generated between the coating film surface and the inner surface in the coating film, thereby causing many convections in the coating film. The structure generated by this convection is called a Benard cell structure, and causes a problem such as the skin and coating defects in the formed antiglare layer. In addition, the Benard cell structure may cause the surface of the antiglare layer to be excessively uneven, resulting in blurring and surface glare. When the leveling agent as described above is used, this convection can be prevented, so that not only a concavo-convex film having no defects or unevenness can be obtained, but also the concavo-convex shape can be easily adjusted.

  Moreover, the composition for anti-glare layers may mix and use a photosensitizer, As a specific example, n-butylamine, a triethylamine, poly-n-butylphosphine etc. are mentioned, for example.

  The above is description of the component contained in the composition for glare-proof layers, and the adjustment method of the composition for glare-proof layers is demonstrated next.

  The method for preparing the composition for an antiglare layer described here is a light that forms organic fine particles and a binder resin in a solvent containing 20% by mass or more of a solvent having a high polarity and a high volatilization rate. A step of adding a polymerizable monomer to prepare a mixture, and a step of adding silica fine particles to the obtained mixture.

  The method for preparing the mixture by mixing the organic fine particles, the photopolymerizable monomer and the solvent is not particularly limited, and may be carried out using a known apparatus such as a paint shaker, a bead mill, a kneader, a disper, or a mixer. it can. In the step of adjusting the mixture, the above-described photopolymerization initiator and other dispersants may be further added. Moreover, the solid content in the mixture prepared in the step of adjusting the mixture is not particularly limited, but is preferably 10 to 90% by mass, and more preferably 30 to 80% by mass.

  Examples of the method of adding silica fine particles to the mixture include a method of adding silica fine particles dispersed in a solvent. At this time, the solvent in which the silica fine particles are dispersed need not contain the above-described solvent having a high polarity and a high volatilization rate. That is, by appropriately adjusting the amount of the solvent in which the silica fine particles are dispersed, the content and solid content of the solvent having a high polarity and a high volatilization rate in the composition for the antiglare layer obtained through this step are as described above. It is preferable to do. Examples of a method for preparing a composition for an antiglare layer by adding silica fine particles dispersed in a solvent to the above mixture include the same methods as those for preparing the above mixture.

  As described above, from the viewpoint of producing the antiglare layer shown in FIG. 3, the silica fine particles are preferably surface-treated, and the organic fine particles are preferably surface-hydrophilized. The surface treatment of the silica fine particles and the surface hydrophilization treatment of the organic fine particles facilitate the aggregation of the silica fine particles and the organic fine particles. Therefore, the silica fine particles and the organic fine particles are aggregated in the composition for the antiglare layer, and further, sedimentation may occur. However, the solvent for the antiglare layer composition described here contains a predetermined amount of a solvent having a high polarity and a high volatilization rate. A solvent having a high polarity and a high volatilization rate has a property of making it difficult to cause aggregation of silica fine particles and organic fine particles. In addition, in the adjustment method described here, silica fine particles are added after organic fine particles are dispersed in a solvent containing a solvent having a high polarity and a high volatilization rate. For this reason, the silica fine particles and the organic fine particles in the prepared anti-glare layer composition are less likely to aggregate, and the silica fine particles and the organic fine particles can be uniformly dispersed in the anti-glare layer composition.

  Next, a method for producing an optical film by forming an antiglare layer on a light-transmitting substrate and an adhesion improving layer using the composition for an antiglare layer adjusted as described above will be described.

  The manufacturing method of the optical film demonstrated here is the process of apply | coating the composition for glare-proof layers on the adhesive improvement layer laminated | stacked on the transparent base material, and the process of forming a coating film, and the process of drying a coating film And a step of curing the dried coating film. In addition, what was already demonstrated can be used for a light transmissive base material and an adhesive improvement layer.

  In the step of forming the coating film, the method for applying the antiglare layer composition on the adhesion improving layer is not particularly limited, and examples thereof include spin coating, dipping, spraying, die coating, and bar coating. Known methods such as a coating method, a roll coater method, a meniscus coater method, a flexographic printing method, a screen printing method, and a speed coater method can be used. The application amount of the antiglare layer composition is not particularly limited, and is appropriately adjusted according to the thickness of the target antiglare layer. In addition, in the coating film formed by this process, it is preferable that the aggregate of silica fine particles and the organic fine particles described above are in a state of being uniformly dispersed.

  In the step of drying the coating film, the method for drying the coating film is not particularly limited, and for example, any conventionally known method can be used. Here, the coating film contains a predetermined amount of the above-described solvent having high polarity and high drying speed. Therefore, when the coating film is dried, the solvent having a high polarity and a high drying rate out of the solvents contained in the coating film is first volatilized. As described above, the solvent having a high polarity and a high drying rate has a property of making it difficult to cause aggregation of the silica fine particles and the organic fine particles. Therefore, when the coating film is dried, the composition having a high polarity and a high drying rate is volatilized first, whereby the composition at the time of forming the coating film is modified. As a result, aggregates of silica fine particles are gathered around the organic fine particles in the coating film, and aggregates of the silica fine particles are gathered together, so that the aggregates of the silica fine particles are in a dense state and around the organic fine particles. A densely distributed state can be formed.

  By selecting the solvent relative evaporation rate, solid content concentration, coating amount, coating solution temperature, drying temperature, drying air speed, drying time, solvent atmosphere concentration in the drying zone, etc., the aggregate of organic fine particles and silica fine particles Can be adjusted. In particular, a method of adjusting the distribution state of the aggregates of organic fine particles and silica fine particles by selecting drying conditions is simple and preferable. Specifically, the drying temperature is preferably 30 to 120 ° C., and the drying wind speed is preferably 0.2 to 50 m / s, and the organic fine particles are obtained by performing drying treatment appropriately adjusted within this range once or plural times. In addition, the distribution state of the aggregates of silica fine particles can be adjusted to a desired state.

  In the step of curing the coating film, a method of curing the coating film includes a method of irradiating the dried coating film with ionizing radiation. Examples of the irradiation method of ionizing radiation include a method using a light source such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc lamp, a black light fluorescent lamp, and a metal halide lamp. Moreover, as a wavelength of an ultraviolet-ray, the wavelength range of 190-380 nm can be used. Specific examples of the electron beam source include various electron beam accelerators such as a cockcroft-wald type, a bandegraft type, a resonant transformer type, an insulated core transformer type, a linear type, a dynamitron type, and a high frequency type.

  As described above, the above-described antiglare layer shown in FIG. 3 is formed on the adhesion improving layer laminated on the light-transmitting substrate, and an optical film is obtained. In the antiglare layer of the obtained optical film, the inorganic fine particles are densely distributed in the binder resin and are densely distributed around the organic fine particles. And, due to the distribution of such organic fine particles and inorganic fine particles, the antiglare layer has a smooth shape in which the slope of the convex portion becomes gentler than the uneven shape formed by a single fine particle or an aggregate thereof. Become. As a result, the optical film 10 can improve the contrast while maintaining the antiglare property. Since the slope of the convex portion of the concave and convex surface is gentle and has a smooth shape, the antiglare layer functions so that only the edge portion of the image reflected on the surface of the antiglare layer is not clearly visible. Furthermore, according to the antiglare layer having such an uneven surface, it is possible to eliminate a large diffusion, so that the generation of stray light can be effectively prevented. In addition, since the amount of light that is transmitted normally can be appropriately secured, the image can be given shine, and the contrast in the bright room and the dark room can be greatly improved.

  By the way, although the details of the reason why the slope of the convex portion becomes gentle due to the distribution of the organic fine particles and the inorganic fine particles described above are unknown, it is presumed that the cause is as follows. In general, when the coating film formed by applying the antiglare layer composition is dried to evaporate the solvent, if the viscosity of the coating film is low, the binder resin tends to follow the shape of the organic fine particles. Furthermore, the volume of the binder resin shrinks when cured, but the organic fine particles do not shrink. Therefore, only the binder resin contracts, so that the convex portion formed on the surface corresponding to the organic fine particles tends to have a steep slope. However, if the aggregates of silica fine particles are densely distributed around the organic fine particles, the viscosity of the coating film increases in a region around the organic fine particles. Therefore, around the organic fine particles in which the silica fine particles are densely distributed, the binder resin hardly follows the shape of the organic fine particles when the coating film is dried, and the binder in that region (consists of the binder resin and the silica fine particles). ) Is difficult to cure and shrink, and as a result, the convex portion formed on the surface corresponding to the organic fine particles tends to have a gentle inclination. For this reason, it is presumed that the inclination angle of the concavo-convex shape (convex portion) formed on the surface of the antiglare layer by the organic fine particles becomes gentler than the inclination angle of the concavo-convex shape (convex portion) formed by the fine particles alone. The

  As already described, the antiglare layer 12 in FIG. 3 in which the organic fine particles 12c and the inorganic fine particles 12d are dispersed in the binder resin 12b is an example of the antiglare layer. Accordingly, the antiglare layer included in the optical film 10 is not limited to the antiglare layer configured as a single layer, and may be an antiglare layer configured of a plurality of layers.

  The antiglare layer 17 shown in FIG. 4 has a base uneven layer 18 and a surface adjustment layer 19 provided on the base uneven layer 18. The foundation uneven layer 18 is a layer having an uneven surface. On the other hand, the surface adjustment layer 19 is a layer for adjusting the surface shape of the base uneven layer 18 to a more appropriate uneven shape. That is, in the antiglare layer 17 shown in FIG. 4, the uneven surface of the antiglare layer 17 is provided by a method different from the antiglare layer 12 shown in FIG. 17A can be formed in gentle irregularities, and the image observed through the optical film can be given brightness and teri like the antiglare layer 12 shown in FIG. In the example shown in FIG. 4, the underlying concavo-convex layer 18 has a binder resin 18 a and fine particles 18 b dispersed in the binder resin 18 a. Concavities and convexities resulting from the presence of the fine particles 18 b are formed on the surface of the underlying uneven layer 18. On the other hand, the surface adjustment layer 19 does not contain fine particles for expressing the light diffusing function, and the surface adjustment layer 19 is formed on the surface of the base uneven layer 18 so as to smooth the unevenness formed on the surface of the base uneven layer 18. Is formed. Such an underlying concavo-convex layer 18 and the surface adjustment layer 19 may be provided with some other function other than the antiglare property. In particular, since the surface adjustment layer 19 does not contain light diffusing fine particles, and the surface adjustment layer 19 is disposed on the viewer side, various functions are suitably imparted to the surface adjustment layer 19. Can do. As an example, the antistatic agent of the optical film 10 can be imparted by adding an antistatic agent to the surface adjustment layer 19.

  4 is similar to the above-described antiglare layer 12 in FIG. 3, for example, (1) Composition for underlying uneven layer including a photopolymerizable compound that becomes a binder resin after polymerization and fine particles. (2) Applying the composition for the base uneven layer to the light transmitting substrate or the adhesion improving layer, and then forming a groove having an uneven surface on the surface. A method for embossing a mold having a substrate with a concave / convex layer, or (3) a composition for a base concave / convex layer in which disk-like particles having a concavo-convex shape corresponding to the concave / convex surface are dispersed, It can be formed by a method of applying to the material or the adhesion improving layer and arranging the disk-like particles on the surface of the underlying uneven layer. Among these, the method (1) is preferable because of easy production. On the other hand, the surface adjustment layer 19 is, for example, (1) a method of applying a composition for a surface adjustment layer containing a photopolymerizable compound that forms a surface adjustment layer after polymerization to a base uneven layer, and (2) a composition for a surface adjustment layer. It can be formed by a method of applying an object to the underlying uneven layer and then embossing the surface adjustment layer composition with a mold having a groove having a reverse surface of the uneven surface on the surface. Among these, the method (1) is preferable because of easy production.

  The photopolymerizable compound, solvent, fine particles, and other additives that form the binder resin included in the composition for the base uneven layer and the composition for the surface adjustment layer form the antiglare layer 12 in FIG. 3 described above. For the same material. However, it is not necessary that the solvent contained in the composition for the base uneven layer and the composition for the surface adjustment layer contains a solvent having a high polarity and a high volatilization rate. In addition, the photopolymerizable compound contained in the composition for the base concavo-convex layer and the composition for the surface adjustment layer does not need to be mainly composed of a polyfunctional acrylate monomer that does not contain a hydroxyl group in the molecule. Further, unlike the composition for producing the antiglare layer 12 of FIG. 3, the composition for the underlying uneven layer does not need to contain both organic fine particles and inorganic fine particles.

  The degree of unevenness of the underlying uneven layer formed is controlled by adjusting the content and particle size of the fine particles contained in the underlying uneven layer composition, the viscosity of the underlying uneven layer composition, the drying conditions of the underlying uneven layer composition, etc. Can be controlled. Further, by adjusting the viscosity of the composition for the surface adjustment layer, the drying conditions of the composition for the surface adjustment layer, etc., the unevenness of the surface adjustment layer formed on the uneven surface of the underlying uneven layer, that is, the antiglare layer 17 The degree of unevenness can be controlled. As a result, the uneven surface 17A of the antiglare layer 17 in FIG. 4 satisfies the above-described conditions a1 to a3, and the optical film 10 including the antiglare layer 17 improves the contrast while maintaining the antiglare property. be able to. Since the convex portion of the concavo-convex surface 17A of the anti-glare layer 17 in FIG. 4 has a gentle slope and has a smooth shape, the anti-glare layer cannot clearly see only the edge portion of the image reflected on the surface of the anti-glare layer. To function. Furthermore, according to the anti-glare layer 17 having such an uneven surface, as in the anti-glare layer 12 of FIG. 3, it is possible to eliminate a large diffusion, so that the generation of stray light can be effectively prevented. In addition, since the amount of light that is transmitted normally can be appropriately secured, the image can be given shine, and the contrast in the bright room and the dark room can be greatly improved.

≪Physical properties of optical film≫
(Total light transmittance)
The optical film 10 preferably has a total light transmittance of 85% or more. When the total light transmittance is 85% or more, color reproducibility and visibility can be further improved when the optical film 10 is mounted on the surface of the image display device. The total light transmittance is more preferably 90% or more. The total light transmittance can be measured by a method based on JIS K7361 using a haze meter (manufactured by Murakami Color Research Laboratory, product number: HM-150).

(Haze)
The optical film preferably has a haze of 5% or less, and more preferably 4% or less. When the haze is 5% or less, the cloudiness can be effectively suppressed, and a surface glossiness is further imparted. Further, when the optical film is placed on the image display surface when the haze is 5% or less, the sharpness of the image is ensured, and the observer can observe an image with excellent visibility. As a result of extensive research by the present inventors, an optical film including the antiglare layer shown in FIG. 3 in which organic fine particles and inorganic fine particles are contained in a binder resin, and the antiglare layer shown in FIG. In the optical film containing the haze, the haze could be 4% or less. Further, even if the haze is 0%, it can have an antiglare property if it has a diffused light intensity at an angle of 1.0 degree or more and less than 2.5 degree. According to such an optical film, it was possible to add brightness to the image and to greatly improve the contrast in the bright room and the dark room. On the other hand, from the viewpoint of sufficiently suppressing surface glare, the haze is preferably 3% or more. In addition, haze can be measured by the method based on JISK7136 using a haze meter (the product number; HM-150 made by Murakami Color Research Laboratory).

(Transparency definition)
The transmission clarity of the optical film measured using an optical comb having a width of 0.125 mm is preferably 85% or less, and the transmission clarity of the optical film is more preferably 80% or less. On the other hand, from the viewpoint of preventing surface glare, it is preferable that the transmission clarity of the optical film measured using an optical comb having a width of 0.125 mm is (numerical value) 60% or more. Moreover, the total value of the transmission clarity of the optical film measured using the 0.125 mm wide optical comb, the 0.5 mm wide optical comb, the 1.0 mm wide optical comb, and the 2.0 mm wide optical comb, respectively. 260% or more is preferable. If the total value of the transmission clarity of the optical film measured using 0.125 mm width, 0.5 mm width, 1.0 mm width and 2.0 mm width optical combs is less than 260%, the glossiness may be impaired. Because there is. The transmission definition can be measured by a transmission definition measuring device based on the image definition transmission method of JIS K7105. As such a measuring apparatus, Suga Test Instruments Co., Ltd. image clarity measuring device ICM-1T etc. are mentioned.

As shown in FIG. 5, the transmission definition device 100 includes a light source 101, a slit 102, a lens 103, a lens 104, an optical comb 105, and a light receiver 106. The transmitted sharpness measuring device 100 converts light emitted from the light source 101 and passing through the slit 102 into parallel light by the lens 103, and irradiates the parallel light to the optical film 10 from a surface opposite to the uneven surface 12A. The light emitted from the irregular surface 12A of the optical film 10 is condensed by the lens 104, and the light that has passed through the optical comb 105 is received by the light receiver 106. Based on the amount of light received by the light receiver 106. Thus, the transmission definition C is calculated by the following equation (5). In formula (a), M is the highest wave height and m is the lowest wave height.
C (%) = {(M−m) / (M + m)} × 100 (5)
The optical comb 105 is movable along the longitudinal direction of the optical comb 105, and has a dark part and a bright part. The ratio of the width of the dark part and the bright part of the optical comb 105 is 1: 1. Here, in JIS K7105, as optical combs, four types of optical combs having a width of a bright part and a dark part of 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm are defined. For this reason, in the present invention, the transmission clarity of the optical film is evaluated using an optical comb having a width of 0.125 mm.

  As a result of extensive research conducted by the present inventors, it was possible to effectively suppress the occurrence of interference fringes on the optical film when the transmission clarity was 85% or less. Further, in the optical film including the antiglare layer shown in FIG. 3 in which organic fine particles and inorganic fine particles are contained in the binder resin, and the optical film including the antiglare layer shown in FIG. 4, the haze is 5%. Even in the following cases, it is confirmed that the transmission sharpness can be 80% or less, and in this optical film having the transmission sharpness of 80% or less, generation of interference fringes can be extremely effectively prevented. It was.

  In general, when the surface of the optical film is a concavo-convex surface, the diffuse transmitted light component increases as compared to a flat surface. If the diffuse transmitted light is present to a certain extent, the rainbow colors generated by the interference are mixed and reach the observer, so that they are no longer recognized as interference fringes. That is, conventionally, the degree of diffusivity of an optical film is considered to be a factor governing the appearance of interference fringes, and an index that is directly expressed as the degree of diffusivity, for example, haze or Invisible interference fringes have been studied by adjusting the surface roughness.

  On the other hand, the transmission definition varies greatly even with a slight change in diffusivity. For this reason, the transmission sharpness can be an index indicating the presence or absence of diffusibility of an optical film that a human observes visually, such as an optical film for a display device, for example, but the degree of diffusivity of an optical film that a human observes visually It could not be an indicator of That is, the transmitted sharpness has been conventionally used exclusively as an index representing, for example, the sharpness of an image formed by transmitted light in the characteristic evaluation of an optical film that is visually observed by a human.

  In addition, among the four optical combs stipulated in JIS K7105, the optical comb having the bright part and the dark part width of 0.125 mm has the narrowest distance between the bright part and the dark part, and is caused by a slight change in the optical path of the transmitted light. However, the measurement results will change. Conventionally, such fluctuations in measurement results are not handled as accurate characteristics evaluation results of optical films, but rather, evaluation methods that lack reliability in optical film characteristics evaluation using 0.125 mm wide optical combs. I was in trouble. Therefore, although defined in JIS, the transmission sharpness measured using an optical comb having a width of 0.125 mm is an optical film that is actually commercially available, particularly an optical film that is visually observed by humans. On the other hand, it has not been practically used. Measurements using 0.125 mm wide optical combs have only been used for characterization of commercially available optical films, in combination with measurements using optical combs of different widths.

  In view of the above background, the effect of invisible interference fringes produced by setting the transmission clarity of an optical film measured using an optical comb having a width of 0.125 mm to 85% or less is the conventional technique. It can be said that it is a remarkable effect that exceeds the range that can be predicted in light of the level.

  As demonstrated by the results in Examples described later, the inventors of the present invention, if the transmission clarity of an optical film measured using an optical comb having a width of 0.125 mm is 85% or less, Although it has been confirmed that the generation of interference fringes on the optical film itself can be effectively suppressed, the details of the mechanism by which such a phenomenon occurs are not clear at present. However, it is estimated that an optical phenomenon in which interference fringes that can be observed on the optical film itself as a target here can occur under very limited conditions is a cause. This estimation will be described below, but the present invention is not limited to this estimation.

  Here, the interference fringes of the optical film to be invisible are the light reflected by the uneven surface of the antiglare layer, the interface between the antiglare layer and the adhesion improving layer, the adhesion improving layer, and the light transmissive substrate. It occurs due to interference with light reflected at the interface between the two. The difference in refractive index at the interface between the antiglare layer and the adhesion improving layer and the interface between the adhesion improving layer and the light-transmitting substrate is very small, and the reflectance at the interface is very low. For this reason, the amount of light reflected at the interface between the antiglare layer and the adhesion improving layer or at the interface between the adhesion improving layer and the light transmissive substrate is extremely small. It is estimated that the interference fringes can be sufficiently invisible by a slight change of the optical path in the optical film because one of the lights forming the interference fringes to be invisible is such a small amount of light. Is done. For this reason, it is speculated that the transmission clarity of an optical film measured using an optical comb having a width of 0.125 mm can be a very important factor in making the interference fringes observed on the optical film invisible. Is done. In other words, the generation of interference fringes on the optical film by imparting to the optical film the ability to change the optical path with respect to the transmitted light with a transmission sharpness of 85% or less measured using an optical comb having a width of 0.125 mm. It is estimated that can be effectively suppressed.

  In view of the above, the interference fringes observed on the optical film are not necessarily eliminated by adjusting the haze and roughness of the optical film, which causes a characteristic change that can be perceived by human eyes. Will be able to. Therefore, the interference fringe countermeasure using the transmission sharpness measured using an optical comb having a width of 0.125 mm as an index is limited to an optical film for which suppression of white turbidity is desired, typically haze is limited to 5% or less. It can be said that it is extremely useful as a countermeasure against interference fringes for optical films.

In addition, the adhesion improving layer is designed to improve the adhesion between the light-transmitting substrate and the antiglare layer. In general, the refractive index of the adhesion improving layer is designed to reduce the reflectance at the interface between the adhesion improving layer and the antiglare layer and at the interface between the adhesion improving layer and the light-transmitting substrate. Is done. Therefore, the optical film in which the adhesion improving layer is provided between the light transmissive substrate and the antiglare layer, particularly the average refractive index n ₂ in the surface of the adhesion improving layer is in the surface of the light transmissive substrate. In the optical film (n ₁ <n ₂ <n ₃ or n ₃ <n ₂ <n ₁ ) between the average refractive index n ₁ and the average refractive index n ₃ in the plane of the antiglare layer, Interference fringes are visible only under more limited conditions. From this point, the countermeasure against interference fringes using the transmission sharpness measured using an optical comb having a width of 0.125 mm as an index is an optical in which an adhesion improving layer is provided between the light-transmitting substrate and the antiglare layer. It can be said that it is very suitable for film. The average refractive index n ₁ in the plane of the light-transmitting substrate, the average refractive index n ₂ in the plane of the adhesion improving layer, and the average refractive index n ₃ in the plane of the antiglare layer are Abbe refractometers ( It can be measured using NAR-4T manufactured by Atago Co., Ltd. or “Ellipsometer M150” manufactured by JASCO Corporation.

  By the way, when the present inventors experimented, the Newton ring generated due to the incomplete optical contact state of the two optical films is invisible even if the transmission clarity of each optical film is 85% or less. could not. In order to make this Newton ring sufficiently invisible, it was necessary to impart a strong diffusibility to the optical film up to a haze exceeding 5%. Newton's ring is caused by interference between reflected light at the interface between one optical film and the gap formed between two optical films and reflected light at the interface between the gap and the other optical film. This phenomenon occurs. That is, each light that causes a Newton ring is reflected light at an interface formed between the gap and a relatively high refractive index difference. Therefore, compared with the interference fringes of the optical film to be invisible in the present case, the amount of each light that causes Newton's ring is remarkably increased, for example, from several times to several tens of times. The result of this experiment conducted by the present inventors is also consistent with the above-described estimation mechanism regarding countermeasures against interference fringes using the transmission clarity measured using an optical comb having a width of 0.125 mm as an index.

  Moreover, when the present inventors confirmed by experiment, in the optical film from which a haze becomes 5% or less, a strong correlation was not found between haze and a transmission clarity. More specifically, a phenomenon occurs in which the measured value of haze does not change significantly even when the measured value of transmission clarity varies. This phenomenon became more prominent as the width of the optical comb used for measuring the transmission definition was reduced. That is, in the optical film having a haze of 5% or less, the correlation between the transmission clarity measured using an optical comb having a width of 0.125 mm and the haze value was very weak. Such experimental results show that the transmission sharpness, particularly the transmission sharpness measured using an optical comb having a width of 0.125 mm, cannot be evaluated by the haze that has been used as an index for countermeasures against interference fringes. It shows that it is evaluating. This point does not conflict with the above-described estimation mechanism related to countermeasures against interference fringes using the transmission sharpness measured with an optical comb having a width of 0.125 mm as an index, but rather matches, and further has a width of 0.125 mm. This clearly supports the remarkableness of the effect of invisible interference fringes produced by setting the transmission sharpness of the optical film measured with the optical comb of 85% or less.

  In addition, the present inventors have confirmed that the interference fringe invisible effect produced by setting the transmission clarity of the optical film measured using an optical comb having a width of 0.125 mm to 85% or less, It appeared more remarkably in the optical film including the antiglare layer shown in FIG. 3 in which organic fine particles and inorganic fine particles were contained in the binder resin, and the optical film including the antiglare layer shown in FIG. That is, the countermeasure against interference fringes using the transmission sharpness measured using an optical comb having a width of 0.125 mm as an index is the antiglare layer shown in FIG. 3 in which organic fine particles and inorganic fine particles are contained in a binder resin. It can be said that it is very suitable for the optical film containing. Although the detailed reason about this point is unknown, it is estimated that the following points are the cause.

  First, as described above, in the antiglare layer shown in FIG. 3 in which organic fine particles and inorganic fine particles are contained in the binder resin, the uneven surface of the antiglare layer becomes gentle within a range where the antiglare property can be exhibited. As a result, brightness is imparted to the image. One factor that may cause such a gently changing uneven surface to be formed is inorganic fine particles that are coarsely dispersed in the binder resin. It is considered that the inorganic fine particles are distributed around the organic fine particles to moderate unevenness caused by the organic fine particles. The gentle unevenness caused by the organic fine particles exhibits sufficient anti-glare properties and can impart brightness to the image. Further, the inorganic fine particles are dispersed roughly in the binder resin even in a region other than the periphery of the organic fine particles, and form irregularities that do not affect the measurement result of haze. Such an optical path change due to minute unevenness is mainly a small deviation angle, not a haze or transmission sharpness measured using a larger width optical comb, but an optical comb having a width of 0.125 mm. It can be evaluated more accurately by the transmission sharpness using. As a result, the optical film including the antiglare layer containing the organic fine particles and the inorganic fine particles in the binder resin is measured using the 0.125 mm wide optical comb without greatly affecting the measured value of haze described above. It is speculated that the transmission clarity of the optical film can be reduced, and that the above-described interference fringe invisibility effect can be effectively exhibited.

  Further, in the optical film 10 shown in FIG. 4, as in the optical film shown in FIG. 3, the concavo-convex surface of the antiglare layer becomes gentle as long as the antiglare property can be exhibited. As a result, the optical film including the antiglare layer having the base uneven layer and the surface adjustment layer is measured using the above-described 0.125 mm wide optical comb without greatly affecting the measured value of haze. It is presumed that the transmission sharpness can be reduced and the interference fringe invisible effect described above can be effectively exhibited.

  As described above, according to the optical film of the present embodiment, the transmission clarity of the optical film measured using a 0.125-width optical comb is 85% or less, and the haze of the optical film is 5 %, The cloudiness is not observed, and the generation of interference fringes can be effectively suppressed. Moreover, according to the optical film according to the present embodiment, it is possible to effectively suppress the generation of interference fringes while eliminating the need for a mixed region, which is advantageous in terms of cost.

≪Polarizing plate≫
The optical film 10 can be used by being incorporated into a polarizing plate, for example. FIG. 6 is a schematic configuration diagram of a polarizing plate incorporating the optical film according to the present embodiment. As shown in FIG. 6, the polarizing plate 20 includes an optical film 10, a polarizing element 21, and a protective film 22. The polarizing element 21 is formed on the surface opposite to the surface on which the antiglare layer 12 is formed in the light transmissive substrate 11. The protective film 22 is provided on the surface opposite to the surface on which the optical film 10 of the polarizing element 21 is provided. The protective film 22 may be a retardation film.

  Examples of the polarizing element 21 include a polyvinyl alcohol film, a polyvinyl formal film, a polyvinyl acetal film, an ethylene-vinyl acetate copolymer saponified film, which are dyed and stretched with iodine or the like. When laminating the optical film 10 and the polarizing element 21, it is preferable to saponify the light-transmitting substrate 11 in advance. By performing the saponification treatment, the adhesiveness is improved and an antistatic effect can be obtained.

≪LCD panel≫
The optical film 10 and the polarizing plate 20 can be used by being incorporated in a liquid crystal panel. FIG. 7 is a schematic configuration diagram of a liquid crystal panel incorporating the optical film according to the present embodiment.

  The liquid crystal panel shown in FIG. 7 includes a protective film 31, such as a triacetyl cellulose film (TAC film), a polarizing element 32, a retardation film 33, an adhesive, from the light source side (backlight unit side) to the viewer side. The layer 34, the liquid crystal cell 35, the adhesive layer 36, the retardation film 37, the polarizing element 21, and the optical film 10 are laminated in this order. In the liquid crystal cell 35, a liquid crystal layer, an alignment film, an electrode layer, a color filter, and the like are disposed between two glass substrates.

  Examples of the retardation films 33 and 37 include a triacetyl cellulose film and a cycloolefin polymer film. The retardation film 37 may be the same as the protective film 22. Examples of the adhesive constituting the adhesive layers 34 and 36 include a pressure sensitive adhesive (PSA).

≪Image display device≫
The optical film 10, the polarizing plate 20, and the liquid crystal panel 30 can be used by being incorporated in an image display device. Examples of the image display device include a liquid crystal display (LCD), a cathode ray tube display device (CRT), a plasma display (PDP), an electroluminescence display (ELD), a field emission display (FED), a touch panel, a tablet PC, and electronic paper. Can be mentioned. FIG. 8 is a schematic configuration diagram of a liquid crystal display which is an example of an image display device incorporating the optical film according to the present embodiment.

  The image display device 40 shown in FIG. 8 is a liquid crystal display. The image display device 40 includes a backlight unit 41 and a liquid crystal panel 30 including the optical film 10 disposed on the viewer side with respect to the backlight unit 41. A known backlight unit can be used as the backlight unit 41.

(Second Embodiment)
Hereinafter, an optical film according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 9 is a schematic configuration diagram of an optical film according to the present embodiment.

≪Optical film≫
As shown in FIG. 9, the optical film 50 has at least a light-transmitting substrate 51 having birefringence in the plane and an antiglare layer 52 provided on the light-transmitting substrate 11. doing. The light transmissive substrate 51 has a retardation Re of 3000 nm or more. The surface of the antiglare layer 52 is formed as an uneven surface 52A. And the transmission clarity of the optical film 50 measured using the 0.125 width optical comb is 85% or less, and the haze of the optical film 50 is 5% or less. According to such an optical film 50, the generation of interference fringes can be effectively prevented as in the optical film 10 described in the first embodiment.

  In the optical film 50 shown in FIG. 9, adhesion between the light transmissive substrate 51 and the antiglare layer 52 for improving the adhesion between the light transmissive substrate 51 and the antiglare layer 52. A property improving layer 53 is provided. Further, in order to improve the adhesion when the optical film 50 is bonded to another member, as shown by a two-dot chain line in FIG. 9, on the side opposite to the adhesion improving layer 53 of the light transmissive substrate 51, A second adhesion improving layer 54 may be provided.

  The optical film 50 has a low refractive index layer 55 provided on the uneven surface 52 </ b> A of the antiglare layer 52. The surface of the low refractive index layer 55 opposite to the antiglare layer 52 side is formed as an uneven surface 55A. The uneven surface 55A of the low refractive index layer 55 has an uneven shape similar to the uneven surface 52A of the antiglare layer 52 or an uneven shape in which the uneven surface 52A of the antiglare layer 52 is slightly smooth. The uneven surface 55 </ b> A forms the surface of the optical film 50 on the viewer side. In the second embodiment, the average interval Sm, the average inclination angle θa, the arithmetic average roughness Ra, and the ten-point average roughness Rz for the uneven surface 55A are the unevenness of the antiglare layer 12 in the first embodiment. It is preferable that the conditions a1, a2 and a3 described for the surface 12A are satisfied for the same reason as described in the first embodiment.

  The optical film 50 in the second embodiment is different from the optical film 10 in the first embodiment in that the low refractive index layer 55 is provided, and in other points, the optical film 50 in the first embodiment. The optical film 10 can be configured similarly. That is, the light-transmitting substrate 51, the antiglare layer 52, the adhesion improving layer 53, and the second adhesion improving layer 54 of the optical film 50 in the second embodiment are the same as the optical film 10 in the first embodiment. The light-transmitting substrate 11, the antiglare layer 12, the adhesion improving layer 13, and the second adhesion improving layer 14 can be similarly configured. Therefore, the low refractive index layer 55 will be mainly described below.

(Low refractive index layer)
The low refractive index layer 55 is for reducing the reflectance when external light (for example, a fluorescent lamp, natural light, etc.) is reflected on the surface of the optical film 50. The low refractive index layer 55 has a lower refractive index than the antiglare layer 53. Specifically, for example, the low refractive index preferably has a refractive index of 1.45 or less, and more preferably has a refractive index of 1.42 or less.

The thickness of the low-refractive index layer 55 is not limited, but may be set appropriately from the range of about 30 nm to 1 μm. The thickness d _A (nm) of the low refractive index layer 55 preferably satisfies the following formula (6).
d _A = m × λ / (4 × n _A ) (6)
In the above formula, nA represents the refractive index of the low refractive index layer, m represents a positive odd number, preferably 1, and λ is a wavelength, preferably a value in the range of 480 nm to 580 nm.

The low refractive index layer 55 preferably satisfies the following formula (7) from the viewpoint of reducing the reflectance.
120 <n _A × d _A <145 (7)

  The effect can be obtained with a single layer of the low refractive index layer, but it is also possible to appropriately provide two or more low refractive index layers for the purpose of adjusting a lower minimum reflectance or a higher minimum reflectance. When two or more low refractive index layers are provided, it is preferable to provide a difference in the refractive index and thickness of each low refractive index layer.

  The low refractive index layer 55 preferably includes 1) a resin containing low refractive index particles such as silica and magnesium fluoride, 2) a fluorine-based resin which is a low refractive index resin, and 3) silica or magnesium fluoride. Fluorine resin, 4) A thin film of a low refractive index material such as silica or magnesium fluoride, etc. can be used. As for the resin other than the fluorine resin, the same resin as the binder resin constituting the antiglare layer described above can be used.

  Further, the silica is preferably hollow silica fine particles, and such hollow silica fine particles can be produced by, for example, a production method described in Examples of JP-A-2005-099778.

  As the fluorine-based resin, a polymerizable compound containing at least a fluorine atom in the molecule or a polymer thereof can be used. Although it does not specifically limit as a polymeric compound, For example, what has hardening reactive groups, such as a photopolymerizable functional group and a thermosetting polar group, is preferable. Moreover, the compound which has these reactive groups simultaneously may be sufficient. In contrast to this polymerizable compound, a polymer has no reactive groups as described above.

  As the photopolymerizable compound, fluorine-containing monomers having an ethylenically unsaturated bond can be widely used. More specifically, to illustrate fluoroolefins (eg, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluorobutadiene, perfluoro-2,2-dimethyl-1,3-dioxole, etc.) Can do. As those having a (meth) acryloyloxy group, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3,3-pentafluoropropyl (meth) acrylate, 2- (perfluorobutyl) ) Ethyl (meth) acrylate, 2- (perfluorohexyl) ethyl (meth) acrylate, 2- (perfluorooctyl) ethyl (meth) acrylate, 2- (perfluorodecyl) ethyl (meth) acrylate, α-trifluoro (Meth) acrylate compounds having a fluorine atom in the molecule, such as methyl methacrylate and α-trifluoroethyl methacrylate; a C 1-14 fluoroalkyl group having at least 3 fluorine atoms in the molecule, fluoro A cycloalkyl group or a fluoroalkylene group and at least two (medium There are also fluorine-containing polyfunctional (meth) acrylic acid ester compounds having an acryloyloxy group.

  Preferable examples of the thermosetting polar group include hydrogen bond forming groups such as a hydroxyl group, a carboxyl group, an amino group, and an epoxy group. These are excellent not only in adhesion to the coating film but also in affinity with inorganic ultrafine particles such as silica. Examples of the polymerizable compound having a thermosetting polar group include 4-fluoroethylene-perfluoroalkyl vinyl ether copolymer; fluoroethylene-hydrocarbon vinyl ether copolymer; epoxy, polyurethane, cellulose, phenol, polyimide, and the like. Examples include fluorine-modified products of each resin.

  The polymerizable compound having both the photopolymerizable functional group and the thermosetting polar group includes acrylic or methacrylic acid moieties and fully fluorinated alkyl, alkenyl, aryl esters, fully or partially fluorinated vinyl ethers, fully or partially. Examples thereof include fluorinated vinyl esters, fully or partially fluorinated vinyl ketones, and the like.

  Examples of the fluorine-based resin include the following. Polymer of monomer or monomer mixture containing at least one fluorine-containing (meth) acrylate compound of a polymerizable compound having an ionizing radiation curable group; at least one fluorine-containing (meth) acrylate compound; and methyl (meth) Copolymers with (meth) acrylate compounds that do not contain fluorine atoms in the molecule such as acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; fluoroethylene , Fluorine-containing compounds such as vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, 3,3,3-trifluoropropylene, 1,1,2-trichloro-3,3,3-trifluoropropylene, hexafluoropropylene Monomer homopolymer or Copolymer such as. Silicone-containing vinylidene fluoride copolymers obtained by adding a silicone component to these copolymers can also be used. The silicone components in this case include (poly) dimethylsiloxane, (poly) diethylsiloxane, (poly) diphenylsiloxane, (poly) methylphenylsiloxane, alkyl-modified (poly) dimethylsiloxane, azo group-containing (poly) dimethylsiloxane, Dimethyl silicone, phenylmethyl silicone, alkyl / aralkyl modified silicone, fluorosilicone, polyether modified silicone, fatty acid ester modified silicone, methyl hydrogen silicone, silanol group containing silicone, alkoxy group containing silicone, phenol group containing silicone, methacryl modified silicone, acrylic Modified silicone, amino modified silicone, carboxylic acid modified silicone, carbinol modified silicone, epoxy modified silicone, mercapto modified silicone Over emissions, fluorine-modified silicones, polyether-modified silicone and the like. Among these, those having a dimethylsiloxane structure are preferable.

  Furthermore, non-polymers or polymers composed of the following compounds can also be used as the fluororesin. That is, a fluorine-containing compound having at least one isocyanate group in the molecule is reacted with a compound having at least one functional group in the molecule that reacts with an isocyanate group such as an amino group, a hydroxyl group, or a carboxyl group. Compound obtained: a compound obtained by reacting a fluorine-containing polyol such as fluorine-containing polyether polyol, fluorine-containing alkyl polyol, fluorine-containing polyester polyol, fluorine-containing ε-caprolactone-modified polyol with a compound having an isocyanate group Can be used.

  Moreover, each binder resin as described in the said glare-proof layer 12 can also be mixed and used with the polymeric compound and polymer which have the above-mentioned fluorine atom. Furthermore, various additives and solvents can be used as appropriate in order to improve the curing agent for curing reactive groups and the like, to improve the coating property, and to impart antifouling properties.

  In the formation of the low refractive index layer 55, the viscosity of the composition for a low refractive index layer obtained by adding the above-described material is 0.5 to 5 mPa · s (25 ° C.), preferably 0. It is preferable to set it as the thing of the range of 7-3 mPa * s (25 degreeC). An antireflection layer excellent in visible light can be realized, a uniform thin film with no coating unevenness can be formed, and a low refractive index layer particularly excellent in adhesion can be formed.

  The curing means for the low refractive index layer composition may be the same as that described for the antiglare layer 12 described above. When a heating means is used for the curing treatment, it is preferable to add a thermal polymerization initiator that generates, for example, a radical by heating to start polymerization of the polymerizable compound, to the fluororesin composition.

  According to the optical film 50 according to the present embodiment, the transmission clarity of the optical film measured using an optical comb having a width of 0.125 is 85% or less, and the haze of the optical film is 5% or less. Thus, no cloudiness is observed and the generation of interference fringes can be effectively suppressed. Moreover, according to the optical film according to the present embodiment, it is possible to effectively suppress the generation of interference fringes while eliminating the need for a mixed region, which is advantageous in terms of cost.

  In order to describe the present invention in detail, examples will be described below, but the present invention is not limited to these descriptions.

<Preparation of composition for antiglare layer>
First, each component was mix | blended so that it might become a composition shown below, and the compositions 1 for anti-glare layers were obtained.

(Anti-glare layer composition 1)
Organic fine particles (hydrophilic treatment acrylic-styrene copolymer particles, average particle size 2.0 μm, refractive index 1.55, manufactured by Sekisui Plastics Co., Ltd.): 3 parts by mass Fumed silica (octylsilane treatment, average particles Diameter 12 nm, manufactured by Nippon Aerosil Co., Ltd .: 1 part by mass, dipentaerythritol hexaacrylate (DPHA) (Product name: DPHA, manufactured by Daicel Cytec Co., Ltd.): 70 parts by mass, urethane acrylate (Product name: UV1700B, Nippon Synthetic Chemical Co., Ltd.) Manufactured, weight average molecular weight 2000, functional group number 10): 30 parts by mass / polymerization initiator (Irgacure 184, manufactured by BASF Japan): 5 parts by mass / polyether-modified silicone (product name: TSF4460, Momentive Performance Materials) Manufactured): 0.025 parts by mass, toluene: 75 parts by mass, isopropyl alcohol Cole: 60 parts by mass / methyl isobutyl ketone: 15 parts by mass The fumed silica is treated with octyl silane (treatment for hydrophobizing octyl silane by replacing silanol groups on the surface of the fumed silica with octyl silyl groups). It was what was done.

(Anti-glare layer composition 2)
Organic fine particles (hydrophilic treatment acrylic-styrene copolymer particles, average particle size 2.0 μm, refractive index 1.55, manufactured by Sekisui Plastics Co., Ltd.): 3 parts by mass Fumed silica (octylsilane treatment, average particles Diameter: 12 nm, manufactured by Nippon Aerosil Co., Ltd .: 0.5 parts by mass, dipentaerythritol hexaacrylate (DPHA) (Product name: DPHA, manufactured by Daicel Cytec Co., Ltd.): 70 parts by mass, urethane acrylate (Product name: UV1700B, Nippon Gosei Co., Ltd.) Chemical company, weight average molecular weight 2000, functional group number 10): 30 parts by mass / polymerization initiator (Irgacure 184, manufactured by BASF Japan): 5 parts by mass / polyether modified silicone (product name: TSF4460, Momentive Performance Material) Product): 0.025 parts by mass, toluene: 75 parts by mass, isopropyl Alcohol: 60 parts by mass Methyl isobutyl ketone: 15 parts by weight

(Anti-glare layer composition 3)
Organic fine particles (hydrophilic treatment acrylic-styrene copolymer particles, average particle size 2.0 μm, refractive index 1.55, manufactured by Sekisui Plastics Co., Ltd.): 6 parts by mass Fumed silica (octylsilane treatment, average particles Diameter 12 nm, manufactured by Nippon Aerosil Co., Ltd .: 1 part by mass, dipentaerythritol hexaacrylate (DPHA) (Product name: DPHA, manufactured by Daicel Cytec Co., Ltd.): 70 parts by mass, urethane acrylate (Product name: UV1700B, Nippon Synthetic Chemical Co., Ltd.) Manufactured, weight average molecular weight 2000, functional group number 10): 30 parts by mass / polymerization initiator (Irgacure 184, manufactured by BASF Japan): 5 parts by mass / polyether-modified silicone (product name: TSF4460, Momentive Performance Materials) Manufactured): 0.025 parts by mass, toluene: 75 parts by mass, isopropyl alcohol Call: 60 parts by mass Methyl isobutyl ketone: 15 parts by weight

(Anti-glare layer composition 4)
Organic fine particles (hydrophilic treatment acrylic-styrene copolymer particles, average particle size 2.0 μm, refractive index 1.55, manufactured by Sekisui Plastics Co., Ltd.): 3 parts by mass Fumed silica (octylsilane treatment, average particles Diameter 12 nm, manufactured by Nippon Aerosil Co., Ltd .: 0.1 parts by mass, dipentaerythritol hexaacrylate (DPHA) (Product name: DPHA, manufactured by Daicel Cytec Co., Ltd.): 70 parts by mass, urethane acrylate (Product name: UV1700B, Nippon Synthetic Co., Ltd.) Chemical company, weight average molecular weight 2000, functional group number 10): 30 parts by mass / polymerization initiator (Irgacure 184, manufactured by BASF Japan): 5 parts by mass / polyether modified silicone (product name: TSF4460, Momentive Performance Material) Product): 0.025 parts by mass, toluene: 75 parts by mass, isopropyl Alcohol: 60 parts by mass Methyl isobutyl ketone: 15 parts by weight

(Anti-glare layer composition 5)
Organic fine particles (non-hydrophilic treatment acrylic-styrene copolymer particles, average particle diameter 2.0 μm, refractive index 1.55, manufactured by Sekisui Plastics Co., Ltd.): 8 parts by mass Dipentaerythritol hexaacrylate (DPHA) ( Product name: DPHA, manufactured by Daicel Cytec Co., Ltd .: 90 parts by mass, urethane acrylate (Product name: UV1700B, manufactured by Nippon Synthetic Chemical Co., Ltd., weight average molecular weight 2000, functional group number 10): 10 parts by mass, polymerization initiator (Irgacure 184) , Manufactured by BASF Japan Ltd.): 5 parts by mass. Polyether-modified silicone (Product name: TSF4460, manufactured by Momentive Performance Materials): 0.025 parts by mass. Toluene: 80 parts by mass. Methyl isobutyl ketone: 70 parts by mass.

(Anti-glare layer-underlying uneven layer composition)
Organic fine particles (hydrophilic treatment acrylic-styrene copolymer particles, average particle size 5.0 μm, refractive index 1.53, manufactured by Sekisui Plastics Co., Ltd.): 15 parts by mass Amorphous silica (average particle size 1.5 μm , Manufactured by Tosoh Silica Co., Ltd.): 5 parts by mass, dipentaerythritol hexaacrylate (DPHA) (product name: DPHA, manufactured by Daicel Cytec): 90 parts by mass, 10 parts by mass of PMMA polymer (molecular weight 75000, Mitsubishi Rayon), polymerization Initiator (Irgacure 184, manufactured by BASF Japan): 5 parts by mass, polyether-modified silicone (Product name: TSF4460, manufactured by Momentive Performance Materials): 0.025 parts by mass, toluene: 80 parts by mass, methyl isobutyl Ketone: 70 parts by mass

(Anti-glare layer-surface adjustment layer composition)
Dipentaerythritol hexaacrylate (DPHA) (Product name: DPHA, manufactured by Daicel Cytec): 90 parts by mass PMMA polymer (molecular weight 75000, Mitsubishi Rayon) 10 parts by mass Polymerization initiator (Irgacure 184, manufactured by BASF Japan) ): 5 parts by mass-polyether-modified silicone (Product name: TSF4460, manufactured by Momentive Performance Materials): 0.025 parts by mass-Toluene: 80 parts by mass-Methyl isobutyl ketone: 70 parts by mass

<Preparation of composition for adhesion improving layer>
Each component was mix | blended so that it might become a composition shown below, and the composition for adhesive improvement layers was obtained.
(Adhesion improving layer composition)
-Aqueous dispersion of polyester resin (solid content 60%): 28.0 parts by mass-Water: 72.0 parts by mass

<Example 1>
The polyethylene terephthalate material was melted at 290 ° C., extruded through a film-forming die, into a sheet form, closely adhered onto a water-cooled and cooled rotating quenching drum, and cooled to produce an unstretched film. This unstretched film was preheated at 120 ° C. for 1 minute with a biaxial stretching test apparatus (manufactured by Toyo Seiki Co., Ltd.), then stretched at 120 ° C. at a stretch ratio of 4.5 times, and then improved in adhesiveness on one side. The layer composition was uniformly applied with a roll coater. Then, the coating film was dried at 95 ° C., the performed stretching at stretching ratio 1.5 times in the direction of 90 degrees to the stretch direction, n x _(refractive index in a slow axis of the optically-transparent substrate) 1.70, n _y (refractive index at the fast axis of the light-transmitting substrate) is 1.60, the thickness is 80 μm, the retardation is 8000 nm, and the film thickness of the adhesion improving layer is 100 nm to obtain a polyethylene terephthalate substrate It was. Next, the antiglare layer composition 1 was applied on the formed adhesion improving layer to form a coating film.

Next, the formed coating film is dried at 70 ° C. for 2 minutes to evaporate the solvent in the coating film, and the accumulated light amount is 100 mJ / cm ² under a nitrogen atmosphere (oxygen concentration of 200 ppm or less). The antiglare layer having a thickness (at the time of curing) of 4 μm was formed by curing the coating film by irradiation. Thus, an optical film according to Example 1 was produced.

<Example 2>
In Example 2, an optical film was produced in the same manner as in Example 1 except that the antiglare layer composition 2 was used instead of the antiglare layer composition 1.

<Example 3>
In Example 3, an optical film was produced in the same manner as in Example 1 except that the thickness of the antiglare layer (at the time of curing) was 4.5 μm.

<Example 4>
In Example 4, an optical film was produced in the same manner as in Example 1 except that the antiglare layer composition 3 was used instead of the antiglare layer composition 1.

<Example 5>
In Example 5, a polyethylene terephthalate base material was prepared in the same manner as in Example 1, and then a base uneven layer composition was applied instead of the antiglare layer composition 1 to form a coating film. Next, the formed coating film was dried at 70 ° C. for 2 minutes to evaporate the solvent in the coating film, and the accumulated light amount was 30 mJ / cm ² under a nitrogen atmosphere (oxygen concentration of 200 ppm or less). The base uneven layer having a thickness (at the time of curing) of 3 μm was formed by irradiating the coating film to cure.

Furthermore, the composition for surface adjustment layers was apply | coated on the formed foundation | substrate uneven | corrugated layer, and the coating film was formed. Next, the formed coating film is dried at 70 ° C. for 2 minutes to evaporate the solvent in the coating film, and the accumulated light amount is 100 mJ / cm ² under a nitrogen atmosphere (oxygen concentration of 200 ppm or less). The surface adjustment layer having a thickness (at the time of curing) of 3 μm was formed by curing the coating film by irradiation. Thus, an optical film according to Example 5 was obtained.

<Example 6>
In Example 6, by adjusting the extrusion amount and the draw ratio at the time of the polyethylene terephthalate substrate formed, _{n x} is 1.69, _{n y} is 1.61, a thickness of 44 .mu.m, retardation polyethylene terephthalate substrate of 3500nm An optical film was produced in the same manner as in Example 1 except that the polyethylene terephthalate substrate was used.

<Comparative Example 1>
In Comparative Example 1, an optical film was produced in the same manner as in Example 1 except that the composition 4 for antiglare layer was used instead of the composition 1 for antiglare layer.

<Comparative example 2>
In Comparative Example 2, an optical film was produced in the same manner as in Example 1 except that the antiglare layer composition 5 was used instead of the antiglare layer composition 1.

<Comparative Example 3>
In Comparative Example 3, by adjusting the extrusion amount and the draw ratio at the time of the polyethylene terephthalate substrate formed, _{n x} is 1.67, _{n y} is 1.63, a thickness of 63 .mu.m, retardation polyethylene terephthalate substrate of 2500nm An optical film was produced in the same manner as in Example 1 except that the polyethylene terephthalate substrate was used.

<Measurement of retardation of light transmissive substrate>
The retardation of the light transmissive substrate used in Examples 1 to 5 and Comparative Examples 1 to 3 was measured as follows. First, a light transmitting substrate after stretching, using two polarizing plates, determined the orientation direction of the film, the refractive index for the wavelength 590nm of the two axes orthogonal to the orientation axis (n _x, n _y ) was determined by an Abbe refractometer (NAR-4T manufactured by Atago Co., Ltd.). Here, an axis showing a larger refractive index is defined as a slow axis. The film thickness d (nm) was measured using an electric micrometer (manufactured by Anritsu), and the unit was converted to nm. Then, the refractive index difference between _(n x -n _y), than the product of the thickness of the film d (nm), was determined retardation. The measurement results of retardation are shown in the “Re” column of Table 1. The measurement results of the refractive index difference _(n x -n _y) shown in the column "Δn" in Table 1.

<Measurement of transmission clarity and haze>
The transmission definition was measured in accordance with JIS K7105 by setting the image clarity measuring device ICM-1T (manufactured by Suga Test Instruments Co., Ltd.) to transmission measurement. The haze was measured with a haze meter HM-150 (Murakami Color Research Laboratory Co., Ltd.) according to JIS K7136. The transmission sharpness measured using an optical comb of 0.125 mm is shown in the column of “Clarity 0.125 mm” in Table 1. The total value of the transmission sharpness of the optical film measured using 0.125 mm width, 0.5 mm width, 1.0 mm width and 2.0 mm width optical combs, respectively, is shown in the column “Total Sharpness” in Table 1. Shown in The measurement result of haze is shown in the “Haze” column of Table 1.

<Nizimura evaluation>
Each optical film obtained in the examples and comparative examples was placed on the observer-side polarizing element of an LED backlight liquid crystal monitor (FLATRON IPS226V (manufactured by LG Electronics Japan)) to prepare a liquid crystal display device. The angle between the slow axis of the polyethylene terephthalate substrate and the absorption axis of the polarizing element on the viewer side of the liquid crystal monitor was set to 45 °. In the dark and bright places (illuminance around the LCD monitor 400 lux), the display image is observed visually and through polarized sunglasses from the front and oblique directions (about 50 degrees), and the presence or absence of nidimra is evaluated according to the following criteria. did. Observation through polarized sunglasses is a much stricter evaluation method than visual observation. The observation is performed by 10 people, and the largest number of evaluations are the observation results.
A: Nijimura was not observed through polarized sunglasses.
◯: Nizimura was observed through polarized sunglasses, but it was thin, no azimuth was observed visually, and it was at a level of no problem in practical use.
Δ: Nizimura was observed through polarized sunglasses, and Nizimura was observed very thin by visual observation.
X: Nizimura was strongly observed through polarized sunglasses, and Nizimura was also observed visually.
The evaluation results of Nijimura are shown in the column “Nizimura” in Table 1.

<Interference fringe observation evaluation>
Black for preventing back surface reflection through a transparent adhesive on the surface opposite to the surface on which the hard coat layer is formed in the polyethylene terephthalate substrate of each optical film obtained in Examples and Comparative Examples. An acrylic plate was attached, each optical film was irradiated with light from the hard coat layer side, and visually observed. As a light source, an interference fringe inspection lamp (sodium lamp) manufactured by Funatech was used. The occurrence of interference fringes was evaluated according to the following criteria.
(Double-circle): The interference fringe was not confirmed.
A: Interference fringes were slightly confirmed, but at a level that was not problematic for practical use.
X: Interference fringes were clearly confirmed.
The evaluation result of interference fringes is shown in the column of “interference fringes” in Table 1.

(Blackness)
The polarizing plate on the outermost surface of the liquid crystal television “KDL-40X2500” manufactured by Sony Corporation was peeled off, and a polarizing plate without surface coating was attached. Next, the antireflection film obtained thereon is transparent adhesive film for optical film (total light transmittance 91% or more, haze 0.3% or less, film thickness 20 to 20 so that the antiglare layer side becomes the outermost surface. A 50 μm product such as MHM series (manufactured by Niei Engineering Co., Ltd.) was applied. Place the LCD TV in a room with an illuminance of approximately 1,000 Lx, display the DVD “Media Phantom” by Media Factory, and place it about 1.5 to 2.0 meters away from the LCD TV Sensory evaluation was performed on the following items by 15 subjects viewing the video from various angles. The evaluation criteria are as follows. When displaying a moving image, the determination was made based on whether or not the image had a high contrast, a three-dimensional effect, and an image that had teri and shine, and felt a dynamic feeling.
◎: Three-dimensional feeling and dynamic feeling were all ◯: One of the three-dimensional feeling or dynamic feeling was ◯ and the other was △: Three-dimensional feeling and dynamic feeling were all △: Three-dimensional feeling Alternatively, at least one of the lively feelings was x, and the three-dimensional feeling and the lively feeling were evaluated according to the following criteria.
(Three-dimensional effect)
○: 10 or more people who answered good △: 5 to 9 people who answered good ×: 4 or less people who answered good (dynamic feeling)
○: 10 or more people who answered good △: 5 to 9 people who answered good ×: 4 or less people who answered that it was good It is shown in the column.

As shown in Table 1, the optical film of Comparative Example 1 is inferior in the evaluation of interference fringes because the transmission clarity of an optical comb having a width of 0.125 exceeds 85%. Moreover, since the haze exceeds 5%, the optical film of Comparative Example 2 is inferior in blackness. Moreover, since the retardation of the optical film of Comparative Example 3 was less than 3000 nm, it was inferior to Nizimura evaluation. On the other hand, the optical films according to the examples were good in any evaluation.

DESCRIPTION OF SYMBOLS 10 Optical film 11 Light transmission base material 12 Anti-glare layer 12A Irregular surface 12b Binder resin 12c Organic fine particle 12d Inorganic fine particle 13 Adhesion improvement layer, 1st adhesion improvement layer 14 Adhesion improvement layer, 2nd adhesion improvement layer 20 Polarizing plate 21 Polarizing element 30 Liquid crystal panel 40 Image display device 50 Optical film 51 Light transmissive substrate 52 Antiglare layer 53 Adhesion improving layer, first adhesion improving layer

Claims (7)

A light transmissive substrate having birefringence in the surface;
An antiglare layer provided on the light-transmitting substrate, and an optical film comprising:
The light transmissive substrate has a retardation of 3000 nm or more,
Transmission visibility is measured using an optical comb of 0.125 width is 85% or less 60%, and state, and are haze of 5% or less,
The antiglare layer includes a binder resin, organic fine particles, and inorganic fine particles,
The inorganic fine particles are coarsely distributed in the binder resin,
Aggregates of the inorganic fine particles are densely distributed around the organic fine particles,
A part of the inorganic fine particles constituting the aggregate of the inorganic fine particles is impregnated on the surface of the organic fine particles, and the aggregate of the inorganic fine particles is impregnated to a depth of 500 nm from the surface of the organic fine particles. An optical film. The light transmissive substrate has a refractive index (n _x ) in the slow axis direction which is the direction in which the refractive index in the plane of the light transmissive substrate is the largest, and a direction orthogonal to the slow axis direction. fast axis direction of the refractive index difference between the _{(n y) (n x -n} y) is 0.05 to 0.20, optical film according to claim 1. A low refractive index layer provided adjacent to the antiglare layer and having a lower refractive index than the antiglare layer;
The low refractive index layer forming the surface of the optical film, the optical film according to claim 1 or 2. The optical film according to any one of claims 1 to 3 , wherein the light-transmitting substrate is a polyester substrate. The optical film according to any one of claims 1 to 4 ,
A polarizing plate comprising: a polarizing element provided on a side opposite to a side where the antiglare layer is provided in the light transmissive substrate of the optical film. A liquid crystal display panel provided with the optical film as described in any one of Claims 1-4 , or the polarizing plate of Claim 5 . An image display apparatus provided with the optical film as described in any one of Claims 1-4 , or the polarizing plate of Claim 5 .