JP2004240411A - Antiglare film, method of manufacturing the same, and display device equipped the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antiglare film which prevents the occurrence of a discoloring and the degradation in visibility by diffraction of light while maintaining an excellent antiglare function, a method for manufacturing the same, and a display device equipped with the same. <P>SOLUTION: The antiglare film has ruggedness formed on its surface. When the specular reflectivity of the light made incident at an angle of 5 to 30° from the normal direction of the antiglare film to a specular reflection direction is defined as R(0) and the reflectivity of the incident light to a direction inclined by ≥30° from the specular reflection direction toward the antiglare film side as R(≥30), R(0) is ≤1% and R(≥30)/R(0) is ≤0.01. That is, when ruggedness formed on the surface of the antiglare film is arranged with the proper dispersion (disorder) satisfying specific conditions, the specular reflectivity of the incident light made incident on the antiglare film from the prescribed angle to the specular reflection direction and the ratio of the reflectivity of the incident light to a direction inclined by the prescribed angle or more from the specular reflection direction to the film side and the specular reflectivity are thereby made to fall onto specific ranges. The antiglare function of the antiglare film is consequently improved and the occurrence of the discoloring and the degradation in visibility by the diffraction of the light are thus sufficiently prevented. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an anti-glare (anti-glare) film, a method for manufacturing the same, and a display device provided with the anti-glare film.

  In an image display device such as a liquid crystal display, a plasma display panel, a CRT display, and an organic EL display, the visibility is significantly impaired when external light is reflected on the display surface. In order to prevent such reflection of external light, televisions and personal computers that place importance on image quality, video cameras and digital cameras used outdoors with strong external light, and mobile phones that perform display using reflected light 2. Description of the Related Art In telephones and the like, conventionally, a film layer for preventing reflection of external light has been provided on the surface of an image display device. This film layer consists of a film that has been subjected to an anti-reflection treatment using interference by an optical multilayer film, and an anti-glare treatment that scatters incident light to blur the reflected image by forming fine irregularities on the surface. The film is roughly divided into those consisting of a film subjected to Among them, the former antireflection film has a problem that the cost is high because a multilayer film having a uniform optical film thickness must be formed. On the other hand, the latter antiglare film is widely used for applications such as large personal computers and monitors because it can be manufactured relatively inexpensively.

  Conventionally, such an anti-glare film has, for example, applied a solvent in which a filler is dispersed on a base sheet, and adjusts the coating thickness to expose the filler to the surface of the coating film, thereby forming random irregularities on the sheet. And the like.

  However, the anti-glare film produced by such a method is difficult to obtain the intended irregularities because the arrangement and shape of the irregularities are affected by the dispersion state and the application state of the filler in the solvent. There is a problem that the anti-glare function cannot be sufficiently obtained. Furthermore, when such a conventional anti-glare film is disposed on the surface of an image display device, the entire display surface becomes whitish due to scattered light, and the display becomes cloudy. there were.

  On the other hand, in a microlens array plate used for a liquid crystal display or the like, generally, irregularly shaped lenses are regularly arranged, and JP-A-9-21903 (Patent Document 1) discloses an adjacent minute lens. A microlens array plate having a shape that is alternately and repeatedly arranged so as not to contact each other is described. However, even in the case of an anti-glare film in which irregularities with such a regular arrangement are formed on the film, light diffraction reflecting the uniform distribution of the distances of the irregularities occurs, and the film looks rainbow-colored. There is a problem that the visibility of the surface is reduced.

JP-A-9-21903

  The present invention has been made in view of the above-mentioned problems of the related art, and has an excellent antiglare function, and has sufficiently prevented the occurrence of white tint and a decrease in visibility due to diffraction of light. It is an object of the present invention to provide a film, a method for manufacturing the film, and a display device including the antiglare film.

  The present inventors have conducted intensive studies to achieve the above object, and as a result, in an antiglare film having unevenness on the surface, the unevenness has a moderate variation (disorder) satisfying specific conditions. By being disposed, the specular reflectance in the specular reflection direction with respect to the incident light incident from the predetermined angle with respect to the antiglare film, and in the direction inclined at a predetermined angle or more toward the film from the specular direction. The ratio between the reflectance for the incident light and the regular reflectance is in a specific range, thereby improving the anti-glare function of the anti-glare film, and reducing the visibility due to the occurrence of whitish or light diffraction. Have been found to be sufficiently prevented, and the present invention has been completed.

  That is, the anti-glare film of the present invention is an anti-glare film having irregularities on its surface, and is suitable for incident light incident at any angle of 5 to 30 ° from the normal direction of the anti-glare film. When the regular reflectance in the reflection direction is R (0) and the reflectance for the incident light in a direction inclined by 30 ° or more from the regular reflection direction toward the antiglare film is R (30 or more), (0) is 1% or less, and the value of R (30 or more) / R (0) is 0.001 or less. By satisfying such conditions, it is possible to obtain an anti-glare film having an excellent anti-glare function and sufficiently preventing the occurrence of white tint and the reduction in visibility due to light diffraction.

  The antiglare film of the present invention preferably has a 60 ° reflection sharpness of 200% or less. By satisfying such conditions, an excellent antiglare function tends to be obtained.

Further, the anti-glare film of the present invention, on the surface of the anti-glare film, a unit cell having a plurality of irregularities is arranged so as to have a translational symmetry with the irregularities in other unit cells, the unit In the cell, when the average value of the shortest distance between the vertices of the irregularities is m ₁ and the standard deviation of the shortest distance is σ ₁ , the value of σ ₁ / m ₁ is represented by the following formula:
0.05 ≦ σ ₁ / m ₁ ≦ 0.3
It is preferable that the following condition is satisfied. By forming the irregularities on the anti-glare film so as to satisfy such a condition, the above-described reflection characteristics are obtained, and while having an excellent anti-glare function, the occurrence of whitish tint and the distance of the irregularities are obtained. Tend to be able to sufficiently prevent a decrease in visibility due to light diffraction reflecting the distribution of the light.

  The method for producing an antiglare film of the present invention includes the steps of: performing a gradation exposure on a photoresist formed on a base material; and performing an exposure process to form irregularities on the photoresist by performing a development process. After electroforming a metal on a resist, an electroforming step of preparing a metal plate on which the uneven shape is transferred by peeling the metal from the photoresist, and forming the uneven shape on a film using the metal plate And a transfer step of transferring. According to such a manufacturing method, it is possible to easily and reliably manufacture the antiglare film of the present invention having the above-described uneven arrangement and the above-described reflection characteristics.

  Further, another method for producing an anti-glare film according to the present invention includes a step of exposing a photoresist formed on a base material to gradation exposure, and then performing a developing process to form irregularities on the photoresist. And electroforming a metal on the photoresist, and then electroforming a metal plate on which the irregularities are transferred by peeling the metal from the photoresist, and winding the metal plate around a roll surface. A manufacturing method characterized by comprising: a roll producing step of producing an embossing roll having the irregularities on its surface, and a transferring step of continuously transferring the irregularities onto a film using the embossing roll. is there. According to such a manufacturing method, there is a tendency that the anti-glare film of the present invention having the above-mentioned arrangement of unevenness and having the above-mentioned reflection characteristics can be manufactured more easily and reliably.

Further, in the transfer step, a unit cell having a plurality of irregularities is arranged so as to have translational symmetry with the irregularities in other unit cells, and in the unit cell, between the vertices of the irregularities. When the average value of the shortest distance is m ₁ and the standard deviation of the shortest distance is σ ₁ , the value of σ ₁ / m ₁ is represented by the following formula:
0.05 ≦ σ ₁ / m ₁ ≦ 0.3
It is preferable to form irregularities on the surface of the film so as to satisfy the above condition. Thereby, the anti-glare film of the present invention having the above-described reflection characteristics tends to be easily and reliably manufactured.

Further, the gradation exposure in the exposure step is performed by performing proximity exposure on the photoresist through a photomask of at least two gradations, and the distance between the photomask and the photoresist is set to L ( μm), and when the outer dimension of the transmitting portion of the photomask is D (μm), the proximity exposure is represented by the following formula:
1.3 ≦ L / D ² ≦ 2.8
Or at least through a multi-tone photomask with respect to the photoresist, or the intensity of the exposure light source can be changed at least depending on the location with respect to the photoresist. It is preferably performed via a spatial light modulator. By performing the gradation exposure in this manner, the anti-glare film of the present invention having the above-described arrangement of the unevenness and having the above-described reflection characteristics tends to be easily and reliably manufactured.

  Further, a display device of the present invention is a display device provided with the above-described antiglare film. Such a display device can obtain high visibility by the excellent anti-glare function of the anti-glare film of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, while having excellent anti-glare function, it is provided with an anti-glare film and a method of manufacturing the anti-glare film, in which the occurrence of whitish tint and the decrease in visibility due to light diffraction are sufficiently prevented, and the anti-glare film Display device can be obtained.

  Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

  FIG. 1 is a schematic diagram showing a light incident direction and a reflection direction with respect to the antiglare film of the present invention. The anti-glare film of the present invention has a specular reflectance R of the reflected light 5 in the specular reflection direction with respect to the incident light 4 incident at any angle θ of 5 to 30 ° with respect to the normal 2 of the anti-glare film 1. In the case of (0), R (0) needs to be 1% or less, and more preferably 0.7% or less. If the specular reflectance R (0) of the anti-glare film exceeds 1%, a sufficient anti-glare function cannot be obtained, and visibility deteriorates.

  FIG. 2 shows the relationship between the angle of inclination of the reflected light 5 with respect to the incident light 4 incident at an angle θ with respect to the normal 2 of the antiglare film 1 from the normal to the antiglare film and the log reflectance. It is a graph. As shown in this graph, the regular reflectance R (0) is generally the peak of the reflectance with respect to the incident light 4 incident at an angle θ, and the reflectance tends to decrease as the angle deviates from the regular reflection direction. In the antiglare film of the present invention, the reflectance for the incident light 4 in the direction inclined by 30 ° or more from the regular reflection direction to the film side in the plane 3 including the normal line 2 and the incident light 4 is R (30 or more). In this case, the value of R (30 or more) / R (0) needs to be 0.001 or less, more preferably 0.0005 or less, and even more preferably 0.0001 or less. If the value of R (30 or more) / R (0) exceeds 0.001, the anti-glare film may be washed out or the light may be diffracted, resulting in reduced visibility. For example, even when black is displayed on the display surface in a state where the antiglare film is installed on the forefront of the display device, light from the surroundings is picked up and the display surface becomes entirely white. In addition, R (30) in FIG. 1 and FIG. 2 is a value corresponding to the incident light 4 of the reflected light 6 in the direction inclined by 30 ° from the regular reflection direction to the film side in the plane 3 including the normal 2 and the incident light 4. The reflectance is shown.

  In measuring the reflectance of the antiglare film of the present invention, it is necessary to accurately measure the reflectance of 0.001% or less, and thus a detector having a wide dynamic range is required. As such a detector, for example, a commercially available optical power meter or the like can be used. An aperture is provided in front of the detector of the optical power meter so that the angle of view of the anti-glare film is 2 °. The measurement can be performed using a variable angle photometer. In addition, visible light of 380 to 780 nm can be used as incident light, and a halogen lamp or the like can be used as a light source. Further, in the case of a transparent antiglare film having a smooth back surface, the influence of reflection from the back surface of the antiglare film may adversely affect the measurement. For example, the antiglare film may be adhered to a black acrylic plate using an adhesive or glycerin. It is preferable to measure only the reflectance of the outermost surface of the antiglare film by optically contacting with a liquid such as the above.

  Further, the antiglare film of the present invention needs to have irregularities formed on the surface. The unevenness is composed of a convex portion and / or a concave portion, and the ratio of the area between the uneven portion and the flat portion on the surface of the antiglare film, the shape of the unevenness, and the like satisfy the above-described conditions for the reflectance of the antiglare film. The ratio is not particularly limited as long as the ratio is small, but the ratio of the area of the flat portion on the surface of the antiglare film is preferably small. The ratio of the area of the flat portion to the entire area of the antiglare film viewed from the front is preferably 30% or less, and more preferably 20%. If the ratio of the area of the flat portion exceeds 30%, the specular reflection component becomes strong, and the antiglare function tends to decrease. Also, the outer shape of the unevenness as viewed from the front of the anti-glare film is defined by the intersection of the surface parallel to the anti-glare film surface and the unevenness at the average value of the height of the unevenness, and as the contour of such an intersection line Examples of the shape include circular, elliptical, polygonal (rectangular, triangular, hexagonal, etc.) and irregular shapes in which these shapes are connected, and circular, oval, or irregular shapes in which these shapes are connected. Preferably, it is shaped. The average value of the outer dimensions of the irregularities is preferably 1 to 50 μm, more preferably 5 to 20 μm. Further, the ratio of the average value of the steps of the irregularities to the average value of the external dimensions of the irregularities (step / exterior dimension) is preferably 0.01 to 0.2, and more preferably 0.05 to 0.1. More preferred. In addition, the said outer dimension means the diameter when the outer shape is circular, and shall mean twice the average distance from the position of the center of gravity to the outer circumference when the outer shape is an ellipse or polygon. . Further, in the antiglare film of the present invention, it is not necessary that all the irregularities have a uniform shape, and the antiglare film may have irregularities having different outer shapes and dimensions.

  The antiglare film of the present invention preferably has a 60 ° reflection sharpness of 200% or less, more preferably 180% or less. When the 60 ° reflection sharpness exceeds 200%, a sufficient antiglare function cannot be obtained, and the visibility tends to be reduced.

  The 60 ° reflection sharpness of the antiglare film in the present invention can be determined in accordance with the method for measuring image sharpness by a reflection method described in JIS K 7105. However, the incident angle of the incident light determined by the above measurement method is 60 °, and the sum of image clarity measured using four types of optical combs having an optical comb width of 2 mm, 1 mm, 0.5 mm, and 0.125 mm. (Up to 400%) was defined as the 60 ° reflection sharpness of the antiglare film of the present invention.

  Next, the arrangement of unevenness in the antiglare film of the present invention will be described.

The anti-glare film of the present invention has, on its surface, a unit cell having a plurality of irregularities, arranged so as to have translational symmetry with the irregularities in other unit cells, and in the unit cells, When the average value of the shortest distance between the vertices of the irregularities is m ₁ and the standard deviation of the shortest distance is σ ₁ , the value of σ ₁ / m ₁ is represented by the following formula:
0.05 ≦ σ ₁ / m ₁ ≦ 0.3
It is preferable that the following condition is satisfied.

  Here, the unit cell having the plurality of irregularities is a specific region including the plurality of irregularities on the surface of the anti-glare film, and in the anti-glare film of the present invention, such a unit cell is used for another unit. They are arranged to have translational symmetry with the unevenness in the cell. Further, in the antiglare film of the present invention, as an example of a state where the unit cells are arranged so as to have translational symmetry, the coordinates of the center of gravity of each unit cell are square lattice, rectangular lattice, and oblique lattice. And a state arranged in a lattice such as a hexagonal lattice. By arranging the unit cells so as to have translational symmetry, the reflection characteristics as described above are obtained, and while having an excellent anti-glare function, the unit cells are visually recognized due to generation of whitish tint and light diffraction. There is a tendency that an antiglare film in which a decrease in the properties is sufficiently prevented is obtained, and the production of the antiglare film also tends to be easy. In the anti-glare film of the present invention, the unit cells may be arranged with higher-order symmetry than translation symmetry.

The value of σ ₁ / m _{1 in} the unit cell can be obtained as follows. That is, first, the coordinates of the vertices of the convex portion or the concave portion on the surface of the anti-glare film are respectively obtained, and the vertex coordinate distance between the adjacent convex portions or between the adjacent concave portions is the shortest vertex coordinate distance, and Defined as the shortest distance between Next, the shortest distance defined in this way is obtained for all the convex portions or concave portions present in the unit cell, and the average value m ₁ and the standard deviation σ ₁ are calculated, and the above σ ₁ / the value of m ₁ can be obtained.

In the antiglare film of the present invention, the value of σ ₁ / m ₁ determined in the unit cell is represented by the following formula:
0.05 ≦ σ ₁ / m ₁ ≦ 0.3
It is preferable that the following condition is satisfied. The lower limit of this σ ₁ / m ₁ is preferably 0.05, but more preferably 0.07, while the upper limit is preferably 0.3. More preferably, it is 25. When the value of σ ₁ / m ₁ is less than 0.05, it is difficult to obtain the above-described reflection characteristics, and in particular, diffraction of light reflecting the distribution of the distance between the concave and convex vertices occurs, resulting in anti-glare. Since the film looks like rainbow colors, the visibility tends to decrease. When the value of σ ₁ / m ₁ exceeds 0.3, it is difficult to obtain the above-described reflection characteristics, and in particular, the anti-glare function cannot be sufficiently obtained, or the anti-glare film is washed out. Visibility tends to decrease.

The average value m ₁ of the shortest distance between uneven vertices in the above unit cell is preferably 200μm or less, more preferably 100μm or less. When m ₁ exceeds 200 μm, the interval between the concavities and convexities is too large and the area of the flat portion is increased, so that the specular reflection component is increased, and it is difficult to obtain the above-described reflection characteristics, and a sufficient anti-glare function is obtained. There is no tendency.

  Since the distribution of the shortest distance between the concave and convex vertices as described above is a statistical amount, it is preferable that the population has a certain size. In the antiglare film of the present invention, the number of irregularities in the unit cell is preferably 20 or more, and more preferably 50 or more. If the number of irregularities is less than 20, the period of the unit cell is shortened, light diffraction reflecting the period of the unit cell occurs, and the antiglare film looks rainbow-colored. Visibility tends to decrease.

  The unit cells in the anti-glare film of the present invention are preferably arranged with translational symmetry on the anti-glare film surface as described above. It is preferable that the period be equal to or longer than the coherence distance. In addition, in order to avoid moire caused by the display device, it is more preferable that the period be larger than the pixel pitch of the display device and not a multiple of the pixel pitch. On the other hand, if the period is too large, the burden on the production and design of irregularities increases, so a specific preferable period is 50 to 10,000 μm in a range satisfying the above preferable conditions, More preferably, it is 100 to 5,000 μm. By having a cycle that satisfies such conditions, there is a tendency that it is possible to sufficiently prevent the visibility of the display surface from lowering due to light diffraction or moire.

  In the anti-glare film of the present invention, that the unit cells are arranged with translational symmetry, the confirmation of the period, for example, a method of observing the surface of the anti-glare film with an optical microscope or the like, Light from a light source such as a coherent laser can be expanded to a beam spot having a period equal to or more than the period of translational symmetry and irradiated on the antiglare film, and the diffraction pattern can be confirmed by a method of observing a diffraction pattern due to the arrangement of irregularities.

Further, it is preferable that the anti-glare film of the present invention is further arranged with an appropriate variation in the unevenness at the boundary between the unit cells as described above. That is, for the irregularities in two adjacent unit cells, the average value m ₂ of the shortest distance between the vertices of the irregularities and the standard deviation σ ₂ of the shortest distance are calculated, and the value of σ ₂ / m ₂ is calculated. Then, the value of σ ₂ / m ₂ is calculated by the following equation:
0.05 ≦ σ ₂ / m ₂ ≦ 0.3
It is preferable that the following condition is satisfied. By determining the value of σ ₂ / m ₂ in two adjacent unit cells in this manner, it is possible to confirm whether or not the arrangement of the unevenness at the boundary between the unit cells is arranged with an appropriate variation. it can. The lower limit of σ ₂ / m ₂ is preferably 0.05, more preferably 0.07, while the upper limit is preferably 0.3, but 0.25. Is more preferable. When the value of σ ₂ / m ₂ is less than 0.05, it is difficult to obtain the above-described reflection characteristics, and in particular, light diffraction reflecting the distribution of the distance between the concave and convex vertices occurs, and the anti-glare property is obtained. Since the film looks like rainbow colors, the visibility tends to decrease. On the other hand, when the value of σ ₂ / m ₂ exceeds 0.3, it is difficult to obtain the above-described reflection characteristics, and in particular, the anti-glare function cannot be sufficiently obtained, or the anti-glare film may be washed out. Visibility tends to decrease.

  Next, a method for producing the anti-glare film of the present invention, which is suitable as a method for obtaining the anti-glare film of the present invention as described above, will be described.

  The method for producing an antiglare film of the present invention includes the steps of: performing a gradation exposure on a photoresist formed on a base material; and performing an exposure process to form irregularities on the photoresist by performing a development process. An electroforming step of preparing a metal plate having the irregularities by stripping the metal from the photoresist after electroforming a metal on the resist, and transferring the irregularities onto a film using the metal plate And a step.

  In the exposure step according to the method for producing an antiglare film of the present invention, first, a photoresist is formed on a substrate to produce a substrate with a photoresist. Here, as the base material, a commonly used base material can be used without particular limitation, for example, an inorganic transparent base material such as glass, quartz, and alumina, and a metal base material such as copper and stainless steel. Etc. can be used. The photoresist is not particularly limited as long as it is a material having photosensitivity.For example, a novolak resin, an acrylic resin, a copolymer of styrene and acrylic acid, a polymer of hydroxystyrene, polyvinyl phenol, poly α A conventionally known positive resist composition obtained by dissolving an alkali-soluble resin such as methylvinylphenol and a quinonediazide group-containing compound in an organic solvent; and a photosensitive composition containing an alkali-soluble resin, a photoacid generator, a crosslinking agent and a dye. A conventionally known negative resist composition obtained by dissolving a reactive resin in an organic solvent can be used.

  The thickness of the photoresist film formed on the substrate may be appropriately adjusted depending on the thickness or shape of the unevenness to be formed on the antiglare film surface of the present invention, and may be equal to or the same as the thickness of the target unevenness. It is preferable to form the film a little thicker. The specific range of the film thickness is preferably equal to or more than the thickness of the target unevenness and equal to or less than the thickness of the target unevenness + 5 μm.

  The method of forming a photoresist on a substrate is not particularly limited, and for example, a film can be formed by a spin coating method, a dip coating method, a roll coating method, or the like. In addition, after film formation, in order to remove a solvent contained in the photoresist, it is preferable to perform prebaking at 60 to 120 ° C. for about 0.5 to 10 minutes using a hot plate, an oven, or the like. The temperature and time of the pre-bake can be appropriately adjusted depending on the type of the photoresist, the sensitivity required for the photoresist, and the like.

  Next, gradation exposure is performed on the photoresist formed on the substrate thus manufactured. The method of performing this gradation exposure can be performed by a conventionally known gradation exposure method, but a method of performing proximity exposure on a photoresist through at least a two-tone photomask, It can be performed by either a method of performing gradation exposure through a mask or a method of performing gradation exposure through a spatial light modulation element that can change the light intensity of an exposure light source at least depending on a location. preferable. Hereinafter, the gradation exposure performed by these methods will be described.

  First, a method of performing proximity exposure on a photoresist through a photomask of at least two gradations will be described. The two-tone photomask used here is a portion that transmits light from the exposure light source and has a transmittance of 100% or close to that portion on a glass or other substrate that is transparent to the exposure light source. , A photomask in which a portion for shielding light from an exposure light source and having a transmittance of 0% or close thereto is formed. Specifically, for example, a metal mask in which a metal such as Cr is formed as a light-shielding portion on a substrate transparent to an exposure light source, an emulsion mask in which a light-shielding portion is formed by exposing an emulsion or the like, and the like are used. No.

  By using such a two-tone photomask and arranging it at an interval from the photoresist surface and performing proximity exposure, light diffraction occurs at the edge of the mask pattern of the photomask, and the photomask The image is blurred, and a continuous light amount distribution is generated from the transmission part to the light shielding part of the photomask. Since the photoresist is exposed according to the distribution of the amount of light exposed by the proximity exposure, when the photoresist is developed, the remaining film of the photoresist changes according to the amount of irradiation, and the developed photoresist surface has a mask pattern and an exposure amount. The unevenness is formed according to. Further, in such an exposure step, an optical system such as a lens system or a mechanical unit such as a mask alignment system may be interposed between the exposure light source and the photoresist within a range that does not impair the above-described operation. Good.

Furthermore, when proximity exposure is performed using the two-tone photomask, the distance between the photomask and the photoresist is L (μm), and the outer dimension of the transmission part of the photomask is D (μm). , The proximity exposure is the following formula:
1.3 ≦ L / D ² ≦ 2.8
Is preferably performed. The reason can be explained as follows. That is, the behavior of light passing through a fine opening is described by Fresnel diffraction and Fraunhofer diffraction, and the spread of an image of light passing through the opening is determined by the distance (L) between the opening and the screen, the opening size (D), and the light. Varies according to the index (L / D ² · λ) consisting of the wavelength λ of When the distance between the opening and the screen is short, the shape of the opening is transferred onto the screen. However, as the distance between the opening and the screen increases, the light becomes diffused with the optical axis as the center. Therefore, when the value of L / D ² is less than 1.3, the exposure image formed on the photoresist reflects the opening pattern on the photomask, and the energy distribution is steep corresponding to the opening shape. Therefore, through holes are easily formed in the photoresist, and the light scattering function of the obtained antiglare film tends to decrease. On the other hand, when the value of L / D ² exceeds 2.8, light diffracted by the photomask is diffused, and it tends to be difficult to form a pattern on the photoresist surface. That is, when the value of L / D ^{2 is in} the range of 1.3 or more and 2.8 or less, there is a tendency that an exposure image suitable as the antiglare film of the present invention can be formed.

  Next, a method of performing a gradation exposure on a photoresist through at least a multi-gradation photomask will be described. The multi-tone photomask used here is a photomask in which the transmittance varies in multiple stages or continuously depending on the location, unlike the two-tone photomask described above. As such a multi-tone photomask, for example, using a high-resolution photomask drawing apparatus such as an electron beam drawing apparatus, a light-shielding portion and a transmission portion each having a size sufficiently smaller than the wavelength of the exposure light are provided. Method of expressing a gradation by the area ratio of the part and the transmissive part to make a gradation mask, mask blanks in which a substance whose transmittance changes when exposed to a high energy beam such as an electron beam or laser is dispersed in a transparent medium In addition, a method in which a high-energy beam whose intensity is changed depending on the location and irradiating the same is used as a gradation mask in which the transmittance is continuously changed, and a method of irradiating light having sensitivity like an emulsion. By forming a material whose optical density changes according to the amount on a transparent substrate, changing the amount of light, exposing the emulsion, and using the optical density changed depending on the location as a gradation mask, etc. Also obtained It can be used.

  By performing gradation exposure using such a multi-gradation photomask, light corresponding to the gradation of the photomask is exposed to the photoresist. Asperities will be formed on the photoresist. Further, in such an exposure step, an optical system such as a lens system or a mechanical unit such as a mask alignment system may be interposed between the exposure light source and the photoresist within a range that does not impair the above-described operation. Good.

  Next, a method of performing gradation exposure on a photoresist through a spatial light modulator capable of changing the light intensity of an exposure light source at least depending on the location will be described. A spatial light modulation element capable of changing the light intensity of an exposure light source depending on the location used here can spatially change the intensity of light transmitted through the element or light reflected by the element. For example, a light modulation element including a large number of pixels, such as a liquid crystal element or a digital micromirror element (DMD), may be used. When the above liquid crystal element is used as a spatial light modulation element, the transmittance can be set for each pixel of the liquid crystal element including a plurality of pixels, so that the spatially uniform intensity distribution from the exposure light source is obtained. Is transmitted through the liquid crystal element, an intensity distribution of the exposure light corresponding to the transmittance of the pixel of the liquid crystal element can be obtained, and a spatial intensity distribution of the exposure light applied to the photoresist is generated. Will be. That is, when the photoresist is developed, the thickness of the photoresist changes in accordance with the intensity of the exposed exposure light, so that it is possible to form irregularities on the surface of the photoresist. When the DMD is used as a spatial light modulator, light may be reflected in the direction of the photoresist due to the inclination angle of the micro mirror, or may be reflected in a direction other than the photoresist. By changing the light reflection time for each pixel, the substantial reflectance per unit time can be changed for each pixel. That is, by reflecting light having a spatially uniform intensity distribution from the exposure light source by the DMD, it is possible to obtain an intensity distribution of the exposure light according to the time during which the micromirror is tilted. A spatial intensity distribution of the exposure light to be irradiated is generated. That is, when the photoresist is developed, the thickness of the photoresist changes in accordance with the intensity of the exposed exposure light, so that it is possible to form irregularities on the surface of the photoresist. The spatial light modulator capable of changing the light intensity of the exposure light source depending on the place used in the exposure step of the present invention is not limited to the liquid crystal element and the DMD as described above. By using a spatial light modulator that can create a spatial intensity distribution of light from a light source, it is possible to create an intensity distribution of exposure light to a photoresist based on the principle described above, and develop the photoresist. Since the film thickness distribution at the time of the etching can be changed, it is possible to form the surface unevenness of the photoresist.

  In the method for manufacturing an antiglare film of the present invention, a proximity exposure method using a two-tone photomask as described above, a tone exposure method using a multi-tone photomask, and a tone exposure method using a spatial light modulation element A substrate having irregularities formed on a photoresist by the method described above is used as an original plate, and finally, the irregularities are continuously transferred onto the film to produce an antiglare film having the desired irregularities. Therefore, it is necessary to design a mask pattern in order to make a photomask for producing an original plate, and this mask pattern is formed so that the arrangement of irregularities necessary for the antiglare film of the present invention as described above is obtained. Need to design. Designing such a mask pattern over the entire surface of a photomask is a very labor-intensive operation, and the load on the mask drawing machine increases due to the large data volume of the mask pattern. In view of the capabilities of this, it is possible in principle but impractical. In the method of performing gradation exposure using a spatial light modulation element when producing an original plate, it is necessary to provide data so that light modulated by the spatial light modulation element has a desired spatial distribution. The labor for generating is large.

  In the method for manufacturing an anti-glare film of the present invention, in order to avoid such problems, a mask pattern corresponding to a unit cell having a plurality of irregularities according to the anti-glare film of the present invention as described above is designed, and this mask is used. The pattern is arranged to have translational symmetry. Here, as an example of a state in which the mask patterns are arranged so as to have translational symmetry, the barycentric coordinates of each mask pattern are in a lattice shape such as a square lattice shape, a rectangular lattice shape, an oblique lattice shape, a hexagonal lattice shape, or the like. Can be listed. This can reduce the trouble of designing the mask pattern of the entire photomask, which is industrially advantageous.

The exposure light source used in the exposure step according to the present invention is not particularly limited as long as it is a light source capable of exposing a photoresist. For example, g-rays and h-rays from a light source such as a high-pressure mercury lamp or an ultra-high-pressure mercury lamp are used. The exposure step can be performed using ultraviolet light or visible light having a wavelength such as i-line or the like, or a laser having an oscillation wavelength near the mercury emission line as a light source. The amount of light to be exposed varies depending on the shape of the target unevenness, the type of photoresist, and the like, and cannot be specified unconditionally. However, it is preferably about 50 to 2000 mJ / cm ² . Further, the exposure time can be appropriately adjusted according to the exposure light source and the required light quantity.

  In the exposure step according to the present invention, the photoresist is subjected to gradation exposure as described above, and then subjected to a development process to form irregularities on the photoresist. In this developing process, for example, the exposed photoresist formed on the substrate is immersed in a developing solution corresponding to the type of the photoresist, and the exposed portion is exposed in the case of a positive resist, and the non-exposed portion is exposed in the case of a negative resist. This is a process for forming irregularities on the photoresist by removing the surface. In addition, as the developing solution, a conventionally known developing solution can be appropriately selected and used according to a photoresist to be used. Further, it is preferable to rinse the photoresist with pure water or the like after development, and it is also preferable to perform post-baking by heating for about 0.5 to 30 minutes in an oven or a hot plate heated to 100 to 200 ° C. Thus, the solvent and moisture in the photoresist can be removed, and the adhesion to the substrate can be improved. The temperature and time of the post-baking can be appropriately adjusted depending on the type of the photoresist and the like.

  In the method for producing an antiglare film of the present invention, after performing the exposure step as described above, a metal is formed on a photoresist by electroforming, and the metal is peeled from the photoresist to produce a metal plate having irregularities. Perform a casting process.

  As the metal used in the electroforming, a metal conventionally used in the electroforming can be used without particular limitation, for example, nickel, nickel-phosphorus alloy, iron-nickel alloy, chromium, chromium alloy and the like. Can be used. The thickness of the metal formed on the photoresist by electroforming is not particularly limited, but is preferably about 0.05 to 3 mm in terms of durability and the like.

  In addition, when performing electroforming directly on the photoresist, it is necessary to make the photoresist conductive before performing the electroforming, and a conventionally known conductive treatment, for example, deposition or sputtering of a metal film having a thickness of 1 μm or less is performed. It can be made conductive by a method such as forming the film, a method using electroless plating, or the like.

  If it is not desired to perform electroforming directly on the photoresist, for example, after transferring the shape of the photoresist to a resin, the resin may be subjected to the above-described conductive treatment and electroforming. After the metal is electroformed on the photoresist in this way, the metal is peeled off from the photoresist to obtain a metal plate having irregularities.

  In the method for producing an antiglare film of the present invention, after performing the electroforming step as described above, a transfer step of transferring the concavo-convex shape onto the film using the obtained metal plate is performed.

  The film used in the transfer step may be made of a single material or a laminate of a plurality of members, but is preferably a laminate of a plurality of members. Hereinafter, a film formed by laminating a plurality of members will be described.

  A film formed by laminating a plurality of members includes, for example, a film in which a thin resin layer is formed on a base sheet made of a thermoplastic resin or an inorganic material, and a transfer process is performed by transferring irregularities to the resin layer. It can be carried out. The sheet used as the base material is polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polymethyl methacrylate, polyarylate, cellulose acetate, cellulose acetate, cellulose acetate, ethylene vinyl alcohol copolymer, norbornene-ethylene copolymer (Mitsui Petrochemical Co., Ltd.) Co., Ltd., trade name: APEL, etc., norbornene-containing resin (Nippon Synthetic Rubber Co., Ltd., trade name: ARTON, etc.), amorphous polyolefin (Nippon Zeon Co., Ltd., trade name: ZEONEX, etc.), optical Thermoplastic resin such as polyester resin (manufactured by Kanebo Co., trade name: O-PET), acryl-butadiene-styrene copolymer (manufactured by Toray Industries, Inc., trade name: Toyolac transparent grade, etc.) is formed into a sheet shape. And inorganic materials such as glass and metal into a sheet Things, and the like.

  On the other hand, examples of the thin resin layer formed on the base sheet include a layer made of a thermoplastic resin, a radiation-curable resin composition, or the like. As the thermoplastic resin, the thermoplastic resins exemplified as the material used for the base material can be used as the resin layer. Examples of the radiation-curable resin composition include radiation-curable resin compositions for various coatings such as hard coats, and radiation-curable resin compositions such as UV inks and EB inks. The compounding raw material of such a radiation-curable resin composition can be adjusted by mixing various monofunctional or polyfunctional (meth) acrylates and the like, and if necessary, a photopolymerization initiator, a sensitizer, and an oxidizing agent. Additives such as inhibitors can be blended. Further, instead of the above (meth) acrylate composition, a composition comprising an epoxy or oxetane compound and a cationic photopolymerization initiator can be used.

  Examples of the monofunctional (meth) acrylate include isobornyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, butoxyethyl acrylate, lauryl acrylate, stearyl acrylate, benzyl acrylate, hexyl diglycol acrylate, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenoxyethyl acrylate, dicyclopentadiene acrylate, polyethylene glycol acrylate, polypropylene glycol acrylate, nonylphenoxyethyl cellosolve acrylate, and the like. As the polyfunctional (meth) acrylate, For example, polyethylene glycol diacrylate, ne Polyfunctional (meth) acrylates such as pentyl glycol diacrylate, trimethylolpropane triacrylate and pentaerythritol triacrylate, and polyfunctional (meth) acrylate oligomers such as oligourethane (meth) acrylate and oligoester (meth) acrylate No. These monofunctional and polyfunctional (meth) acrylates can be used alone or in combination of two or more.

  Examples of the photopolymerization initiator compounded as required include benzophenone, acetophenone, benzoin, benzoin isobutyl ether, benzoin isopropyl ether, benzoin ethyl ether, 4,4′-bis (dimethylamino) benzophenone, benzyldimethyl Ketal, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,2′-diisopropylthioxanthone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane Examples thereof include 1-one, 2,4,6-trimethylbenzoylphenyl diphosphine oxide, and these can be used alone or in combination of two or more.

  Further, the radiation-curable resin composition can be diluted with various solvents as needed for the purpose of adjusting viscosity and improving coatability. As such a diluting solvent, various general organic solvents can be used. For example, alcohol compounds such as methanol, ethanol, 1-propanol and 2-propanol, acetone, ketone compounds such as methyl ethyl ketone, ethyl acetate, Examples include ester compounds such as propyl acetate and butyl acetate, and aromatic compounds such as toluene and xylene, and these can be used alone or in combination of two or more.

  In the transfer step according to the method for manufacturing the antiglare film of the present invention, as a method of transferring the irregularities formed on the metal plate onto the film as described above, a general transfer method can be used, for example, A method of pouring the radiation-curable resin composition or the like into irregularities of a metal plate, irradiating ultraviolet rays or electron beams to cure the resin composition, and transferring the irregularities to the surface of the resin composition, or as described above. By transferring a suitable thermoplastic resin to a temperature higher than the Tg or softening point of the resin and then pressing the same against the surface of the metal plate, the transfer step can be performed by a method of transferring an uneven shape onto the surface of the resin. When the size of the irregularities on the surface of the metal plate and the average distance between the irregularities are small, it is preferable to use a radiation-curable resin composition having a lower viscosity than a thermoplastic resin. Although the transfer step can be performed by such a conventionally known method, in the method for manufacturing an antiglare film of the present invention, before performing the transfer step, a metal plate having irregularities is wound around the surface of a roll. It is preferable to perform a roll producing step of producing an embossing roll having irregularities on the surface by applying the embossing roll, and it is preferable to perform a transferring step by continuously transferring the irregularities onto the film using the embossing roll. By using such a method, it is possible to continuously and efficiently transfer an uneven shape to a film having a large area, and to obtain high productivity.

  The method for manufacturing an anti-glare film of the present invention includes the above-described exposure step, electroforming step, and transfer step, thereby having the unevenness arrangement as described above and having the reflection characteristics. The antiglare film of the invention can be easily and reliably manufactured.

  The anti-glare film obtained by the present invention can be used by installing it on the surface of a display device such as a liquid crystal display, a plasma display panel, a CRT display, and an organic EL display. For installation on a display device, for example, the anti-glare film of the present invention may be directly bonded to the surface of the display device, or in the case of a liquid crystal display or the like, first bonded to a polarizing plate, and then this is bonded to the surface of the display device. You may make it stick to. The display device provided with such an antiglare film of the present invention can scatter the incident light due to the unevenness of the surface of the antiglare film, blur the reflected image, and obtain excellent visibility.

  Hereinafter, the present invention will be described more specifically based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

(Example 1)
First, 75 circular openings having a diameter of 9 μm (= D) are placed in an area of 127 μm × 127 μm square, the average value m ₁ of the shortest distance between the center coordinates of each opening is 14.7 μm, and the standard deviation σ of the shortest distance ₁ was set to 1.049. This was arranged as a unit cell over the entire area of 80 mm × 80 mm at a period of 127 μm to produce a 6-inch square two-tone photomask.

Next, a positive photoresist (PR13, trade name, manufactured by Tokyo Ohka Co., Ltd.) was spin-coated on the glass substrate to a thickness of about 1.1 μm. The obtained glass substrate with a photoresist was placed on a hot plate heated to 110 ° C. for 60 seconds and prebaked. The above photomask is held on this photoresist so that the exposure gap becomes 180 μm (= L), and the light of the g, h, and i multilines of the ultra-high pressure mercury lamp as the exposure light source becomes 150 mJ / cm ^{2 in} h-line conversion. And the proximity exposure was performed. At this time, the value of L / D ² was 2.22.

  The exposed glass substrate with photoresist was immersed in a 0.5% aqueous potassium hydroxide solution at 23 ° C. for 80 seconds, developed, and rinsed with pure water. Thereafter, by heating in an oven heated to 200 ° C. for 18 minutes, a photoresist having unevenness on the surface was obtained.

  On the photoresist thus obtained, a nickel film was formed by an evaporation method, and the photoresist was subjected to a conductive treatment. Next, a nickel film is formed on this photoresist by electroforming so as to have a thickness of about 0.3 mm, and a nickel film having a thickness of 0.2 mm is formed on the back surface of the nickel film with the nickel film adhered on the photoresist. It was polished to become. The polished nickel film was peeled off from the photoresist to obtain a metal plate having an uneven surface.

  As the material for the film, 50 parts by weight of UF8001 (trade name, manufactured by Kyoeisha Chemical Co., Ltd., oligourethane acrylate), 50 parts by weight of IBXA (trade name, manufactured by Kyoeisha Chemical Co., Ltd., isobornyl acrylate), and Irgacure 184 (trade name) And Ciba Specialty Chemicals Co., Ltd.) were mixed to obtain an ultraviolet curable resin composition (hereinafter referred to as UV resin).

The UV resin thus obtained was poured onto the irregularities of the metal plate so as to have a thickness of about 7 μm, and the surface was covered with a PET film having a thickness of 80 μm. After irradiating this with a high-pressure mercury lamp so that the light amount becomes 200 mJ / cm ² to cure the UV resin, the PET film is peeled off from the metal plate together with the UV resin, and the UV resin and the PET film having irregularities on the surface are removed. Was obtained.

The obtained antiglare film was irradiated with light having a wavelength of 543.5 nm from a He-Ne laser, and a diffraction pattern was observed. The corresponding period from the angle from the zero-order light spot up to 1 order light spots was calculated, 14.7Myuemu next was the average value m ₁ of the shortest distance between the convex apexes of the antiglare film surface was used It was equal to the average value of the shortest distance of the opening of the photomask. Further, 1.049 next was the standard deviation sigma _1, consistent with a standard deviation of the minimum distance of the opening of the photomask used. The value of σ ₁ / m ₁ calculated from these was 0.07. Also, when the corresponding period was calculated from the angle of the diffraction spot which looks like a square lattice, it was 127 μm, which coincided with the period of the unit cell of the photomask used.

(Comparative Example 1)
An AG6 film (manufactured by Sumitomo Chemical Co., Ltd.) was prepared as an antiglare film. Irregularities of AG6 film surface has a irregular placement throughout the film surface, the average value m ₁ of the shortest distance between the convex apexes is 8.8 .mu.m, the standard deviation sigma ₁ is 2.87, sigma the value of ₁ / _{m 1} was 0.326.

[Measurement of reflectance]
The reflectance profiles of the antiglare films obtained in Example 1 and Comparative Example 1 were measured as follows. That is, an optical power meter (optical power meter ML9001, manufactured by Anritsu Corporation) is used as a detector, an aperture is provided in front of the detector, and measurement is performed using a goniophotometer in which an angle at which a sample is viewed becomes 2 °. Was done. The reflectance was measured using a halogen lamp (SPH-100, manufactured by Chuo Seiki Co., Ltd.) as a light source, and using a condensing optical system with a focal length of 300 mm, placing 15 mm light at a distance of 300 mm at the exit of the condensing optical system. The light was condensed to 2.5 mmφ on the sample placed. With respect to the reflectance, the light amount when the optical power meter detected the light through a 5 mmφ aperture disposed 165 mm away from the sample without setting anything at the sample position was defined as 100%. Thereafter, the anti-glare films obtained in Example 1 and Comparative Example 1 were attached as samples, the angle of incident light from a light source on the anti-glare film was set to 15 °, and the detector provided with the aperture was used as an anti-glare film. , And the angle dependence of the reflectance was measured to obtain a reflectance profile. FIG. 3 shows the obtained reflectance profile. Further, a reflectance profile when the angle of the incident light from the light source to the antiglare film was set to 30 ° was obtained in the same manner as in the above measurement method. FIG. 4 shows the obtained reflectance profile.

  From the obtained measurement results, the reflectance when the angle of the incident light from the light source to the antiglare film was set to 15 ° was the specular reflection in the specular reflection direction for the incident light in the antiglare film of Example 1. The reflectance R (0) is 0.42%, the reflectance R (30) in the direction inclined 30 ° from the regular reflection direction toward the film is 0.00013%, and the value of R (30) / R (0) is obtained. Was 0.00031. In the anti-glare film of Comparative Example 1, the regular reflectance R (0) in the regular reflection direction with respect to the incident light was 0.23%, and the reflectance R (0) in the direction inclined by 30 ° from the regular reflection direction to the film side. 30) was 0.00048%, and the value of R (30) / R (0) was 0.0069. In the anti-glare films of Example 1 and Comparative Example 1, the reflectance R (30 or more) with respect to incident light in a direction inclined by 30 ° or more toward the film from the specular reflection direction is as shown in FIG. R (30) or less.

  When the angle of the incident light from the light source to the anti-glare film is set to 30 °, the reflectance of the anti-glare film of Example 1 in the specular reflection direction R (0) in the specular reflection direction with respect to the incident light Is 0.48%, the reflectance R (30) in the direction inclined by 30 ° to the film side from the regular reflection direction is 0.0001% or less, which is below the detection limit, and the value of R (30) / R (0) Was 0.0002 or less. In the anti-glare film of Comparative Example 1, the specular reflectance R (0) in the specular direction with respect to the incident light was 0.25%, and the reflectivity R (0) in the direction inclined by 30 ° from the specular direction to the film side. 30) was 0.00212%, and the value of R (30) / R (0) was 0.0085. In the anti-glare films of Example 1 and Comparative Example 1, the reflectance R (30 or more) with respect to incident light in a direction inclined by 30 ° or more from the specular reflection direction to the film side is as shown in FIG. R (30) or less.

[Measurement of 60 ° reflection sharpness]
The anti-glare film obtained in Example 1 and Comparative Example 1 was evaluated for its 60 ° reflection clarity by applying a black vinyl tape to the back surface of the anti-glare film and suppressing reflection from the back surface, using ICM- manufactured by Suga Test Instruments Co., Ltd. It was measured using 1DP. As a result, the 60 ° reflection sharpness was 114.3% for the antiglare film of Example 1 and 24.0% for the antiglare film of Comparative Example 1.

[Measurement of total light transmittance and haze]
The total light transmittance and haze of the antiglare films obtained in Example 1 and Comparative Example 1 were measured using a haze computer (HGM-2DP, manufactured by Suga Test Instruments Co., Ltd.). As a result, the total light transmittance of the antiglare film of Example 1 was 82.1% and the haze was 17.7%, and the total light transmittance of the antiglare film of Comparative Example 1 was 88.3% and the haze was It was 24.9%.

[Evaluation of anti-glare function]
The anti-glare films obtained in Example 1 and Comparative Example 1 were stuck on a black acrylic plate with an adhesive, and illuminated with a tubular fluorescent lamp (manufactured by Otsuka Electronics Co., Ltd., model ENV-B type). The luminance of the light reflected from the antiglare film was measured using a luminance meter (BM7, manufactured by Topcon Corporation, 2 ° visual field) installed in the linear direction. The luminance was measured by adjusting the incident angle of light by changing the height of the tubular fluorescent lamp so that the incident angle to the antiglare film became 10 °, 15 °, 20 °, and 30 °. The brightness of the reflected light of the antiglare film with respect to the light at the incident angle was measured. As a result, in the antiglare film of Example 1, the reflected light luminance for each incident angle was 61.4 cd / m ² , 15.6 cd / m ² , 7.9 cd / m ² , and 7.3 cd / m ² . there were. Further, in the antiglare film of Comparative Example 1, respectively reflected light intensity for each angle of ^{incidence, 74.2cd / m 2, 60.1cd /} m 2, 47.2cd / m 2, 33.2cd / m 2 met Was. As is apparent from the results, the reflected light luminance of the anti-glare film of Example 1 was lower than that of the anti-glare film of Comparative Example 1 with respect to the light incident from any angle. It was confirmed that the glare function was excellent. Further, in the anti-glare film of Example 1, the reflected light luminance sharply decreases as the incident angle of light increases, and the difference from the reflected light luminance of the anti-glare film of Comparative Example 1 increases. From this, it was confirmed that the anti-glare film of Example 1 had a reduced occurrence of white tint due to scattered light, as compared with the anti-glare film of Comparative Example 1. The occurrence of this discoloration was further confirmed by the following visual evaluation.

[Evaluation of light brown and light diffraction]
The anti-glare films obtained in Example 1 and Comparative Example 1 were stuck together on a black acrylic plate with an adhesive, and a bright room (two 40W-type straight tube fluorescent lamps were grouped and arranged every 3 m) In an office environment), the light from a pair of fluorescent lamps was arranged so that the incident angle was 30 °, and visually observed by a tester from the normal direction of the anti-glare film. The film only appeared slightly whiter than the surrounding black acrylic plate, but the antiglare film of Comparative Example 1 looked white and cloudy as compared to the surrounding black acrylic plate. From the result of this visual evaluation, it was confirmed that the anti-glare film of Example 1 had reduced occurrence of whitish tint and improved visibility compared to the anti-glare film of Comparative Example 1. .

  In addition, when the tester observed a decrease in visibility due to light diffraction by the same visual evaluation method, the anti-glare film of Example 1 slightly showed a rainbow color which was considered to be due to light diffraction. No decrease in visibility was observed. On the other hand, in the antiglare film of Comparative Example 1, a rainbow color, which is considered to be due to light diffraction, was observed, and a decrease in visibility was recognized.

[Visibility evaluation when pasted to display device]
The anti-glare films obtained in Example 1 and Comparative Example 1 were bonded to a polarizing plate, and bonded to the surface of a liquid crystal display, to produce a display device provided with the anti-glare film of the present invention. The same image is displayed on these display devices, and the angle of incidence of light from a set of fluorescent lamps in a bright room (office environment in which two 40W-type straight tube fluorescent lamps are grouped and arranged every 3 m) is set. When the display device was arranged so as to be at 30 ° and the tester visually checked the antiglare property from the normal direction of the display device, the display device provided with the antiglare film of Example 1 showed a display image. No reduction in visibility was observed and sufficient anti-glare properties were confirmed. However, in the display device provided with the anti-glare film of Comparative Example 1, reflection of external light occurred and visibility of the displayed image was lowered. Was.

  As is evident from the above results, the anti-glare film of the present invention (Example 1) exhibits an excellent anti-glare function as compared with the anti-glare film of Comparative Example 1, and has visibility due to discoloration and light diffraction. It has been confirmed that the decrease in the temperature was sufficiently prevented.

FIG. 3 is a schematic diagram illustrating a light incident direction and a reflection direction with respect to the antiglare film of the present invention. 5 is a graph showing the relationship between the angle of inclination of the reflected light with respect to the incident light incident at an angle θ with respect to the normal to the antiglare film and the log reflectivity from the normal to the antiglare film in the reflection direction. 4 is a graph showing the results of a reflectance profile for light incident at an angle of 15 ° with respect to the antiglare films obtained in Example 1 and Comparative Example 1. 5 is a graph showing a result of a reflectance profile with respect to light incident at an angle of 30 ° with respect to the antiglare films obtained in Example 1 and Comparative Example 1.

Explanation of reference numerals

  DESCRIPTION OF SYMBOLS 1 ... Anti-glare film, 2 ... Normal line of anti-glare film, 3 ... Surface containing normal line and incident light, 4 ... Incident light, 5 ... Reflected light in the regular reflection direction , 6... Reflected light in a direction inclined by 30 ° to the film side from the regular reflection direction.

Claims (10)

An antiglare film having irregularities formed on its surface,
The specular reflectance in the specular direction with respect to the incident light incident at any angle of 5 to 30 ° from the normal direction of the antiglare film is R (0),
When the reflectance for the incident light in a direction inclined by 30 ° or more from the regular reflection direction to the antiglare film side is R (30 or more),
An antiglare film, wherein R (0) is 1% or less and R (30 or more) / R (0) is 0.001 or less.   2. The anti-glare film according to claim 1, wherein the 60 [deg.] Reflection sharpness is 200% or less. On the surface of the anti-glare film, a unit cell having a plurality of irregularities is arranged so as to have a translational symmetry with the irregularities in other unit cells,
In the unit cell, when the average value of the shortest distance between the vertices of the irregularities is m ₁ and the standard deviation of the shortest distance is σ ₁ , the value of σ ₁ / m ₁ is represented by the following formula:
0.05 ≦ σ ₁ / m ₁ ≦ 0.3
The anti-glare film according to claim 1 or 2, wherein the following condition is satisfied. After performing gradation exposure on the photoresist formed on the base material, an exposure step of forming irregularities on the photoresist by performing a development process,
After electroforming a metal on the photoresist, an electroforming step of producing a metal plate to which the irregularities are transferred by peeling the metal from the photoresist,
A transfer step of transferring the uneven shape onto a film using the metal plate,
A method for producing an antiglare film, comprising: After performing gradation exposure on the photoresist formed on the base material, an exposure step of forming irregularities on the photoresist by performing a development process,
After electroforming a metal on the photoresist, an electroforming step of producing a metal plate to which the irregularities are transferred by peeling the metal from the photoresist,
Roll production step of winding the metal plate around the surface of the roll to produce an embossed roll having the irregularities on the surface,
A transfer step of continuously transferring the uneven shape onto the film using the embossing roll,
A method for producing an antiglare film, comprising: In the transfer step, a unit cell having a plurality of irregularities is arranged so as to have translational symmetry with the irregularities in other unit cells, and, in the unit cell, a shortest distance between vertices of the irregularities. Is the average value of m ₁ and the standard deviation of the shortest distance is σ ₁ , the value of σ ₁ / m ₁ is represented by the following formula:
0.05 ≦ σ ₁ / m ₁ ≦ 0.3
The method for producing an antiglare film according to claim 4, wherein irregularities are formed on the surface of the film so as to satisfy the following condition. The gradation exposure in the exposure step is performed by performing proximity exposure on the photoresist through a photomask of at least two gradations,
When the distance between the photomask and the photoresist is L (μm), and the outer dimension of the transmission part of the photomask is D (μm), the proximity exposure is represented by the following formula:
1.3 ≦ L / D ² ≦ 2.8
The method for producing an antiglare film according to any one of claims 4 to 6, wherein the method is performed.   The anti-glare according to any one of claims 4 to 6, wherein the gradation exposure in the exposing step is performed on the photoresist through at least a multi-gradation photomask. Film production method.   7. The method according to claim 4, wherein the gradation exposure in the exposing step is performed via a spatial light modulation element capable of changing the light intensity of an exposure light source at least depending on a location on the photoresist. The method for producing an anti-glare film according to any one of the above.   A display device comprising the anti-glare film according to claim 1.

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