JP5196352B2 - Method for producing antiglare film, method for producing antiglare film and mold - Google Patents

Description

  The present invention relates to a method for producing an antiglare (antiglare) film and an antiglare film obtained by the production method. Moreover, this invention relates to the manufacturing method of the metal mold | die suitably used for the gradation pattern used for the manufacturing method of the said anti-glare film, and the manufacturing method of the said anti-glare film.

  In an image display device such as a liquid crystal display, a plasma display panel, a cathode ray tube (CRT) display, an organic electroluminescence (EL) display, and the like, when external light is reflected on the display surface, visibility is significantly impaired. Conventionally, in order to prevent such reflection of external light, display is performed using a television or personal computer that emphasizes image quality, a video camera or digital camera that is used outdoors with strong external light, and reflected light. In a cellular phone or the like, a film layer for preventing reflection of external light is provided on the surface of an image display device. This film layer consists of a film that has been subjected to anti-reflection treatment using interference by the optical multilayer film, and anti-glare treatment that scatters incident light by blurring the incident light by forming fine irregularities on the surface. It is divided roughly into the thing which consists of the film which was given. The former non-reflective film is costly because it is necessary to form a multilayer film having a uniform optical film thickness. On the other hand, since the latter anti-glare film can be manufactured at a relatively low cost, it is widely used in applications such as large personal computers and monitors.

  Conventionally, such an antiglare film is based on random surface irregularities by, for example, applying a resin solution in which fine particles are dispersed on a substrate sheet while adjusting the film thickness and exposing the fine particles to the coating film surface. It is manufactured by a method of forming on a material sheet. However, the antiglare film manufactured using a resin solution in which such fine particles are dispersed has an influence on the arrangement and shape of surface irregularities depending on the dispersion state and application state of the fine particles in the resin solution. It is difficult to obtain surface irregularities as described above, and when the haze of the antiglare film is set low, there is a problem that a sufficient antiglare effect cannot be obtained. Furthermore, when such a conventional anti-glare film is disposed on the surface of the image display device, the entire display surface becomes whitish due to scattered light, and the display becomes cloudy, so-called “whiteness” is likely to occur. There was a problem. Also, with the recent high definition of image display devices, the pixels of the image display device and the surface uneven shape of the antiglare film interfere with each other, and as a result, a luminance distribution occurs and the display surface becomes difficult to see. There was also a problem that the “glare” phenomenon was likely to occur. In order to eliminate glare, there is an attempt to scatter light by providing a refractive index difference between the binder resin and the fine particles dispersed therein, but such an antiglare film is disposed on the surface of the image display device. In some cases, there is a problem that the contrast tends to be lowered due to light scattering at the interface between the fine particles and the binder resin.

  On the other hand, there is also an attempt to develop anti-glare properties only by fine irregularities formed on the surface of the transparent resin layer without containing fine particles. For example, in Japanese Patent Laid-Open No. 2002-189106 (Patent Document 1), a three-dimensional 10-point average roughness on a transparent resin film and an average distance between adjacent convex portions on a three-dimensional roughness reference surface are described. Further, an antiglare film is disclosed in which a cured product layer of an ionizing radiation curable resin layer having fine surface irregularities each satisfying a predetermined value is laminated. This antiglare film is manufactured by curing the ionizing radiation curable resin in a state where the ionizing radiation curable resin is sandwiched between the embossing mold and the transparent resin film. However, even with the antiglare film disclosed in Patent Document 1, it has been difficult to achieve a sufficient antiglare effect, suppression of whitening, high contrast, and suppression of glare.

  As a method for producing a film having fine irregularities formed on the surface, a method of transferring the irregular shape of a roll having an irregular surface to the film is known. As a method for producing a roll having such a concavo-convex surface, for example, in JP-A-6-34961 (Patent Document 2), a cylindrical body is made using a metal or the like, and electronic engraving, etching, sandblasting, or the like is performed on the surface. A method of forming irregularities by the above method is disclosed. Japanese Patent Application Laid-Open No. 2004-29240 (Patent Document 3) discloses a method for producing an embossing roll by the bead shot method, and Japanese Patent Application Laid-Open No. 2004-90187 (Patent Document 4). There has been disclosed a method for producing an embossing roll through a step of forming a metal plating layer on the surface, a step of mirror polishing the surface of the metal plating layer, and a step of peening if necessary.

  However, in such a state that the surface of the embossing roll is subjected to blasting treatment, the uneven diameter distribution caused by the particle size distribution of the blast particles is generated, and the depth of the dent obtained by blasting can be controlled. It was difficult to obtain an uneven shape excellent in antiglare function with good reproducibility.

  Further, Patent Document 1 described above describes that a concavo-convex surface is formed by a sandblasting method or a bead shot method, preferably using a roller having a chromium plating on the surface of iron. Furthermore, it is preferable to use the mold surface with such irregularities after applying chrome plating for the purpose of improving durability during use, thereby making it harder and preventing corrosion. There is also a statement that it is possible. On the other hand, in each Example of Unexamined-Japanese-Patent No. 2004-45471 (patent document 5) and Unexamined-Japanese-Patent No. 2004-45472 (patent document 6), the iron core surface is chromium-plated and liquid sandblasting of # 250 is performed. After that, it is described that chrome plating is performed again to form a fine uneven shape on the surface.

  However, in such an embossing roll manufacturing method, since blasting and shots are performed on chromium plating with high hardness, it is difficult to form unevenness, and it is difficult to precisely control the shape of the formed unevenness. It was.

  Japanese Patent Application Laid-Open No. 2000-284106 (Patent Document 7) describes performing an etching process and / or a thin film laminating process after subjecting a base material to sandblasting. Japanese Patent Application Laid-Open No. 2006-53371 (Patent Document 8) describes that an electroless nickel plating is performed after a substrate is polished and sandblasted. Japanese Patent Application Laid-Open No. 2007-188792 (Patent Document 9) discloses that an embossed plate is produced by performing copper plating or nickel plating on a substrate, polishing, sandblasting, and then performing chromium plating. It is described. Furthermore, Japanese Patent Application Laid-Open No. 2007-237541 (Patent Document 10) discloses that after copper plating or nickel plating, polishing, sand blasting, etching or copper plating, and chromium plating are performed. To produce an embossed plate. In these production methods using sandblasting, it is difficult to form the surface uneven shape in a precisely controlled state, so that a relatively large uneven shape having a period of 50 μm or more is also produced in the surface uneven shape. As a result, there is a problem that the so-called glare that the large uneven shape and the pixels of the image display device interfere with each other and a luminance distribution is generated and the display surface is difficult to see is likely to occur.

JP 2002-189106 A JP-A-6-34961 JP 2004-29240 A JP 2004-90187 A JP 2004-45471 A JP 2004-45472 A JP 2000-284106 A JP 2006-53371 A JP 2007-188792 A JP 2007-237541 A

  It is an object of the present invention to exhibit excellent anti-glare performance when applied to an image display device while having low haze, and to prevent deterioration in visibility due to whitishness, and to achieve high definition. Even when applied to an image display device, it is to provide a method for producing an antiglare film capable of expressing high contrast without causing glare, and an antiglare film obtained by the production method. Moreover, the other objective of this invention is to provide the manufacturing method of the metal mold | die suitably used for the gradation pattern used for the manufacturing method of the said anti-glare film, and the manufacturing method of the said anti-glare film.

The present invention relates to a method for producing an antiglare film including a step of forming an uneven surface on a transparent substrate using a gradation pattern. The gradation pattern has a minimum length of one side of 15 mm or more, and the energy spectrum of the gradation pattern shows a maximum value within a spatial frequency range of 0.025 to 0.125 μm ⁻¹ . In the method for producing an antiglare film of the present invention, the concavo-convex surface formed on the transparent substrate has a repetitive structure of concavo-convex surface units (concavo-convex surface units) composed of concave portions and convex portions corresponding to the gradation of the gradation pattern. A structure in which a plurality of these are repeatedly arranged.

  In the method for producing an antiglare film of the present invention, image data created by a computer can be preferably used as the gradation pattern. The image data as the gradation pattern is preferably binarized into white and black. In the case where the gradation pattern is image data binarized into white and black, the concave / convex surface unit is composed of a concave portion and a convex portion corresponding to the gradation of the binarized image data. Any one of the concave portion or the convex portion constituting the concave / convex surface unit corresponds to a white region of the binarized image data.

  The step of forming the concavo-convex surface on the transparent substrate includes a step of producing a mold having an uneven surface using the gradation pattern and transferring the uneven surface of the mold onto the transparent substrate. Is preferred.

  Moreover, this invention provides the manufacturing method of the metal mold | die suitably used for the manufacturing method of the anti-glare film of the said invention. The method for producing a mold of the present invention includes a first plating process for performing copper plating or nickel plating on a surface of a mold base, a polishing process for polishing a surface plated by the first plating process, A photosensitive resin film forming step of forming a photosensitive resin film on the coated surface, an exposure step of exposing the gradation pattern on the photosensitive resin film, and developing the photosensitive resin film exposed to the gradation pattern A developing process, a first etching process that performs etching using the developed photosensitive resin film as a mask and forms irregularities on the polished plated surface, and a photosensitive resin film peeling process that peels the photosensitive resin film And a second plating step of performing chromium plating on the formed uneven surface.

  The mold manufacturing method of the present invention includes a second etching step in which the uneven shape of the uneven surface formed by the first etching step is blunted by an etching process between the photosensitive resin film peeling step and the second plating step. It is preferable to include.

  It is preferable that the concavo-convex surface formed with the chromium plating formed in the second plating step is the concavo-convex surface of the mold transferred onto the transparent substrate. That is, it is preferable to use the concavo-convex surface subjected to chromium plating as the concavo-convex surface of the mold transferred onto the transparent substrate without providing a step of polishing the surface after the second plating step.

  The chromium plating layer formed by chromium plating in the second plating step preferably has a thickness of 1 to 10 μm.

Furthermore, the present invention provides the antiglare film obtained by the method for producing an antiglare film of the present invention, and the minimum length of one side used in the method for producing the antiglare film of the present invention, and In addition, the present invention relates to a gradation pattern that exhibits a maximum value in an energy spectrum within a spatial frequency range of 0.025 to 0.125 μm ⁻¹ . The gradation pattern of the present invention is preferably image data binarized into white and black.

  According to the present invention, when applied to an image display device while having a low haze, it exhibits excellent anti-glare performance, and can prevent deterioration in visibility due to whitishness, and also has high definition. Even when applied to an image display device, an antiglare film that exhibits high contrast without causing glare can be produced with good reproducibility.

It is a figure which expands and shows a part of example of the gradation pattern preferably used for the manufacturing method of the glare-proof film of this invention, and is the gradation pattern used in the case of metal mold | die preparation of Example 1 and Example 3. It is a figure which expands and shows a part. It is a figure which shows typically a preferable example of the first half part of the manufacturing method of the metal mold | die of this invention. It is a figure which shows typically a preferable example of the second half part of the manufacturing method of the metal mold | die of this invention. It is a figure which shows typically the state which side etching advances in a 1st etching process. It is a figure which shows typically the state where the uneven surface formed by the 1st etching process dulls by the 2nd etching process. It is a figure which expands and shows a part of gradation pattern used in the case of metal mold | die preparation of Example 2. FIG. It is a figure which expands and shows a part of gradation pattern used in the case of metal mold | die preparation of Comparative Examples 1-3. It is a figure which expands and shows a part of gradation pattern used in the case of metal mold | die preparation of the comparative example 4. It is a figure which expands and shows a part of gradation pattern used in the case of metal mold | die preparation of the comparative example 5. It is a figure which expands and shows a part of gradation pattern used in the case of metal mold | die preparation of the comparative example 6. FIG. It is a figure which expands and shows a part of gradation pattern used in the case of metal mold | die preparation of the comparative example 7. Example 1 is a diagram showing a cross section taken along f _x = 0 Example 2 is calculated from the gradation pattern used for the energy spectrum ^{_{G 2 (f x, f y}} ).

<Method for producing antiglare film>
Hereinafter, preferred embodiments of the present invention will be described in detail. The manufacturing method of the anti-glare film of this invention is characterized by including the process of forming a fine uneven surface (fine uneven surface) on a transparent base material using a specific gradation pattern. Here, the “gradation pattern” is typically image data composed of a gradation of 2 gradations or 3 gradations or more created by a computer, which is used to form a fine uneven surface of an antiglare film. However, it can also include data (such as matrix data) that can be uniquely converted to the image data. Examples of data that can be uniquely converted to image data include data in which only the coordinates and gradations of each pixel are stored. Forming concave and convex surface units corresponding to one gradation pattern on the transparent substrate by forming concave and convex portions on the transparent substrate so as to correspond to the gradation of such gradation pattern Is possible. In the method for producing an antiglare film of the present invention, the fine uneven surface formed on the transparent substrate can have a repeated structure of uneven surface units in which two or more uneven surface units are closely and repeatedly arranged.

(Gradation pattern)
In the present invention, as the gradation pattern, a pattern having a minimum side length of 15 mm or more and a maximum value in the energy spectrum in the range of the spatial frequency of 0.025 to 0.125 μm ⁻¹ is used. . Based on such a gradation pattern, by forming a fine uneven surface on a transparent substrate, it exhibits excellent anti-glare performance when applied to an image display device while being low haze, and is also white It is possible to provide an antiglare film that can prevent a reduction in visibility and can exhibit high contrast without causing glare even when applied to a high-definition image display device. .

That is, by using a gradation pattern having a maximum value in the range of the spatial frequency of 0.025 to 0.125 μm ^{−1 in} the energy spectrum, a fine uneven surface showing a specific spatial frequency distribution, more specifically, 10 It is possible to accurately form a fine concavo-convex surface including a surface shape having a period of ˜50 μm as a main component, thereby sufficiently suppressing glare while exhibiting a sufficient anti-glare effect (such as an anti-reflection effect). can do. When the fine uneven surface of the antiglare film contains a long-period component exceeding 50 μm, it tends to cause glare when placed on the surface of a high-definition image display device, and contains only a short-period component less than 10 μm. There is a tendency that the antiglare effect such as the antireflection effect is insufficient on the fine uneven surface.

  Also, in the antiglare film produced by repeatedly arranging the uneven surface units corresponding to a certain pattern to form a fine uneven surface, interference color due to interference with external light can be seen or placed on the surface of the image display device However, according to the present invention, the minimum length of one side of the gradation pattern is set to 15 mm or more. An antiglare film that can effectively prevent the occurrence of moire can be obtained. Note that even if the minimum length of one side of the gradation pattern is less than 15 mm, interference color and moire may not occur. However, if the minimum length of one side of the gradation pattern is less than 10 mm, the interference color In order to prevent the occurrence of interference colors and moire with certainty, the minimum length of one side of the gradation pattern is preferably set to 15 mm or more.

Furthermore, when forming a fine uneven surface by repeatedly arranging uneven surface units corresponding to a certain pattern, when the surface of the anti-glare film is observed by applying external light, the repetitive pattern (for example, square based on a square pattern) There is a concern that when a fine concavo-convex surface is formed by closely and repeatedly arranging the concavo-convex surface units, a lattice-like line forming a boundary line of each concavo-convex surface unit is observed, but the minimum length of one side By using a gradation pattern having a maximum value within a range of 15 mm or more and an energy spectrum within a spatial frequency range of 0.025 to 0.125 μm ⁻¹ , such a repetitive pattern is not observed. An extremely excellent antiglare film can be obtained.

  Here, the “minimum length of one side” of the gradation pattern means the length of the shortest side among the sides constituting the outline of the gradation pattern. The outer shape of the gradation pattern is not particularly limited as long as the minimum length of one side is 15 mm or more, and examples thereof include a polygon having a side of 15 mm or more, such as a triangle, a quadrangle, and a hexagon. It is preferable that the gradation pattern has an outer shape that can be densely filled without forming a region where the pattern is not arranged when a plurality of patterns are repeatedly arranged adjacently on a plane. Thereby, when forming a fine uneven | corrugated surface on a transparent base material using a gradation pattern, it can prevent that the area | region where an unevenness | corrugation is not formed arises. From this point of view, the outer shape of the gradation pattern is preferably a polygon rather than a circular curve. When the outer shape of the gradation pattern is a polygon such as a triangle, a quadrangle, or a hexagon, the length of each side may be the same or a different length. The minimum length of one side of the gradation pattern is preferably 16 mm or more, and more preferably 20 mm or more. The upper limit of the length of the minimum side of the gradation pattern is not particularly limited, but is preferably 300 mm or less from the viewpoint of suppressing an increase in calculation load when image data is created by a computer.

Next, the energy spectrum of the gradation pattern will be described. As described above, the gradation pattern used in the present invention has a maximum value in the energy spectrum within the range of the spatial frequency of 0.025 to 0.125 μm ⁻¹ . By forming a fine uneven surface based on the gradation pattern showing such spatial frequency characteristics, it has excellent anti-glare performance and visibility with suppressed glare, whitish, interference color, moire and repeated patterns An excellent antiglare film can be obtained.

In the case where the gradation pattern is image data, the energy spectrum of the gradation pattern is obtained by converting the gradation pattern data into a gray scale of 256 gradations, and then converting the gradation of the gradation pattern data into a two-dimensional function g (x , it expressed in y), resulting two-dimensional function g (x, y) Fourier transform to two-dimensional function G (f _x, calculates the f _y), the resulting two-dimensional function G (f _x, f _y ) is obtained by squaring. Here, x and y represent orthogonal coordinates in the gradation pattern data plane (for example, the x direction is the horizontal direction of the gradation pattern as the image data, and the y direction is the vertical direction of the gradation pattern as the image data. there), respectively f _x and f _y, x-direction spatial frequency represents the spatial frequency in the y direction. Actually, the two-dimensional function g (x, y) indicating the gradation of the image data is a discrete function because the gradation for each pixel is obtained as a set of discrete data points. Therefore, to calculate the discrete function G (f _x, f _y) by a discrete Fourier transform defined by equation (1), discrete function G (f _x, f _y) energy spectrum by squaring the is obtained. Here, π in the formula (1) is a circular ratio, and i is an imaginary unit. M is the number of pixels in the x direction, N is the number of pixels in the y direction, l is an integer from −M / 2 to M / 2, and m is from −N / 2 to N / 2. It is an integer. Furthermore, Delta] f _x and Delta] f _y is the spatial frequency intervals of the x and y directions, is defined by equation (2) and (3). In the expressions (2) and (3), Δx and Δy are horizontal resolutions in the x-axis direction and the y-axis direction, respectively. When the gradation pattern is image data, Δx and Δy are equal to the length of one pixel in the x-axis direction and the length in the y-axis direction, respectively. That is, when a gradation pattern is created as 6400 dpi image data, Δx = Δy = 4 μm, and when a gradation pattern is created as 12800 dpi image data, Δx = Δy = 2 μm.

The gradation pattern is image data, as described below, to create the base as a pattern arranged dots randomly number, or which, energy spectrum ^{_{G 2 (f x, f y}} ) , the horizontal, vertical, the heights f _x, f _y, the energy spectrum ^{_{G 2 (f x, f y}} ) when expressed in three-dimensional graph to become symmetric point about the origin of f _x = 0 and f _y = 0 . Thus, "spatial frequency showing the maximum value of the energy spectrum" in the present invention, the energy spectrum ^{_{G 2 (f x, f y}} ) in FIG. (Horizontal axis showing a section of f _x = 0 of, be a spatial frequency f _y And a spatial frequency obtained from a two-dimensional graph in which the vertical axis is an energy spectrum. In this two-dimensional graph, the spatial frequency f _y of the horizontal axis, since the energy spectrum is symmetrical with regard f _y = 0, can be the absolute value of the spatial frequency f _y.

In the present invention, the term "energy spectrum exhibits a maximum in the range of spatial frequencies 0.025～0.125Myuemu ^-1", the energy spectrum _{^{G 2 (f x, f y}} ) in f _x = 0 of In the diagram showing the cross section, the energy spectrum includes a plurality of maximum values, and one or more of these maximum values are included in the spatial frequency range of 0.025 to 0.125 μm ⁻¹ .

FIG. 1 is an example of a gradation pattern (specifically, a gradation pattern used in the mold production of Example 1 and Example 3) preferably used in the method for producing an antiglare film of the present invention. It is a figure which expands and shows a part. In the present invention, the specific pattern shape of the gradation pattern is such that the minimum side length is 15 mm or more, and the energy spectrum has a maximum value within the spatial frequency range of 0.025 to 0.125 μm ^−1. However, the pattern may be a pattern in which a large number of dots (white areas in FIG. 1) are randomly arranged as shown in FIG. 1, for example. The gradation pattern shown in FIG. 1 is two-gradation image data binarized into white and black (image resolution: 12800 dpi), and one kind of dot having a dot diameter (dot diameter) of 16 μm. Are arranged at random. This gradation pattern is a square with a side of 20 mm, and the energy spectrum shows a maximum value at a spatial frequency of 0.046 μm ⁻¹ .

When creating a gradation pattern by arranging a large number of such dots at random, a large number of dots having one type of dot diameter may be arranged at random, or a large number of dots having a plurality of types of dot diameters. May be arranged at random. The average dot diameter of dots (average value of dot diameters of all dots in the pattern) is not particularly limited, but is preferably 6 to 30 μm. When the average dot diameter is less than 6 μm or more than 30 μm, the energy spectrum may not show a maximum value within the spatial frequency range of 0.025 to 0.125 μm ⁻¹ .

  In the case where the gradation pattern is image data, as a means for randomly drawing a large number of dots, for example, a pseudo-random number sequence R [b] taking values from 0 to 1 for an image having a width WX and a height WY. For example, a method of generating a large number of dots having an x coordinate of WX × R [2 × a−1] and a y coordinate of WY × R [2 × a] is generated. Here, both a and b are natural numbers. As a method for generating the pseudo random number sequence, any pseudo random number generation method can be used as long as it has a sufficient period length corresponding to the number of dots to be distributed, such as a linear congruential method, Xorshift or Mersenne twister. Alternatively, the first pattern in which dots are randomly arranged may be created by hardware that generates a random number by thermal noise or the like, not limited to a pseudorandom number.

  Further, the gradation pattern used in the present invention may be pattern data obtained by performing a specific operation on pattern data formed by arranging a large number of the dots at random. As such an operation, for example, (i) an operation of applying a high-pass filter that removes a low spatial frequency component having a spatial frequency equal to or lower than a specific lower limit value B, and (ii) lower than a specific lower limit value B ′. A low spatial frequency component consisting of a spatial frequency and a high spatial frequency component consisting of a spatial frequency exceeding a specific upper limit value T ′ are removed, and the spatial frequency consists of a specific range from the lower limit value B ′ to the upper limit value T ′. For example, an operation of applying a bandpass filter for extracting a spatial frequency component can be given.

According to the gradation pattern obtained by applying the high-pass filter of (i) above, the low spatial frequency component is removed from the spatial frequency component that can be included in a pattern in which a large number of dots are randomly arranged. However, it becomes more difficult to form a fine uneven surface having a thickness of more than 50 μm, and glare can be prevented more effectively. The lower limit B can be set within a range of 0.02 to 0.05 μm ⁻¹ , for example.

Further, according to the gradation pattern obtained by applying the bandpass filter of (ii) above, from the spatial frequency component that can be included in the pattern in which a large number of dots are randomly arranged, the low spatial frequency component and the high spatial frequency Since the components are removed, a fine uneven surface with a period exceeding 50 μm is less likely to be formed, and it is possible to prevent glare more effectively, and the uneven surface is formed on the transparent substrate using a gradation pattern. Processing reproducibility at the time of forming can be improved. The lower limit B ′ is, for example, 0.01 μm ⁻¹ or more, preferably 0.02 μm ⁻¹ or more. The upper limit value T ′ is preferably 1 / (D × 2) μm ⁻¹ or less. Here, D (μm) is a resolution of a processing apparatus used when forming a concavo-convex surface on a transparent substrate (for example, a laser in a case where a resist is exposed using a laser drawing apparatus to form a concavo-convex surface. Spot diameter).

When creating a gradation pattern by arranging a large number of dots at random, or when applying a high-pass filter or band-pass filter to this, the dot diameter, dot density, lower limit B of the high-pass filter, band-pass filter By appropriately controlling the lower limit value B ′, the upper limit value T ′, and the like, it is possible to obtain a gradation pattern in which the energy spectrum exhibits a maximum value within the spatial frequency range of 0.025 to 0.125 μm ⁻¹ . The dot density (ratio of the area in which dots are drawn relative to the entire gradation pattern area) is preferably 20 to 80%, and more preferably 40 to 70%.

  In the case where the step of forming the uneven surface on the transparent substrate includes a resist work using a laser drawing apparatus or the like, the gradation pattern used in the method for producing an antiglare film of the present invention is white and black. It is preferable that the image data is binarized. This is because, for example, in the case where a resist work using a laser drawing apparatus or the like is included, the concave / convex shape is usually formed by, for example, binary of whether or not the laser is irradiated. For image data of three or more gradations, it is possible to easily convert the image data into binarized image data by setting an appropriate threshold value in consideration of the ratio of the exposure area in the resist work or the like.

(Formation of uneven surface using gradation pattern)
In the manufacturing method of the anti-glare film of this invention, a fine uneven surface is formed on a transparent base material using the above-mentioned gradation pattern. The fine uneven surface to be formed is composed of concave and convex portions corresponding to the gradation of the gradation pattern. In the case where the gradation pattern is image data binarized into white and black, either the concave portion or the convex portion constituting the fine uneven surface corresponds to the white area of the binarized image data. . Further, in the present invention, the fine uneven surface formed on the transparent substrate is formed by repeatedly and closely arranging uneven surface units composed of recesses and protrusions corresponding to the gradation of one gradation pattern. It may be a fine uneven surface having a repeating structure. The fine uneven surface having such a repetitive structure can be formed by using pattern data created by repeatedly arranging two or more gradation patterns as image data, or the fine unevenness corresponding to one gradation pattern. It can also be formed by successively and repeatedly forming the surface (uneven surface unit). Further, a mask corresponding to one gradation pattern can be produced, a plurality of the masks can be repeatedly arranged, and the entire surface can be formed through a mask as described later.

  Specific examples of the method for forming a fine uneven surface on a transparent substrate using the gradation pattern include a printing method, a pattern exposure method, and an embossing method. In the printing method, for example, the above-described gradation pattern is printed on a transparent substrate by flexographic printing, screen printing, inkjet printing, or the like using a photocurable resin or a thermosetting resin, and then dried, or The antiglare film of the present invention can be produced by curing with actinic rays or heating. In the pattern exposure method, after applying a photocurable resin on a transparent substrate, direct exposure with a laser using the above-described gradation pattern, or entire exposure through a mask having the above-described gradation pattern. Thus, the antiglare film of the present invention can be produced by performing pattern exposure, developing as necessary, and curing by actinic rays or heating. Further, in the embossing method, a mold having a fine uneven surface is manufactured using the gradation pattern described above, the uneven surface of the manufactured mold is transferred onto a transparent substrate, and then the transparent substrate on which the uneven surface is transferred. By removing the material from the mold, the antiglare film of the present invention can be produced. Here, the antiglare film of the present invention is preferably produced by an embossing method from the viewpoint of producing a fine uneven surface with good accuracy and reproducibility.

  Examples of the embossing method include a UV embossing method using a photocurable resin and a hot embossing method using a thermoplastic resin. Among these, the UV embossing method is preferable from the viewpoint of productivity.

  The UV embossing method forms a photocurable resin layer on the surface of a transparent substrate, and cures the photocurable resin layer while pressing the photocurable resin layer against the uneven surface of the mold so that the uneven surface of the mold is a photocurable resin. It is a method of transferring to a layer. Specifically, an ultraviolet curable resin is applied onto a transparent substrate, and the ultraviolet curable resin is irradiated with ultraviolet rays from the transparent substrate side while the coated ultraviolet curable resin is in close contact with the uneven surface of the mold. The mold resin is cured, and then the shape of the mold is transferred to the ultraviolet curable resin by peeling the transparent substrate on which the cured ultraviolet curable resin layer is formed from the mold.

  When the UV embossing method is used, the transparent substrate may be a substantially optically transparent film. For example, a triacetyl cellulose film, a polyethylene terephthalate film, a polymethyl methacrylate film, a polycarbonate film, or a norbornene compound is used as a monomer. And a resin film such as a solvent cast film of thermoplastic resin such as amorphous cyclic polyolefin and an extruded film.

  The type of the ultraviolet curable resin in the case of using the UV embossing method is not particularly limited, and a commercially available appropriate one can be used. It is also possible to use a resin that can be cured by visible light having a wavelength longer than that of ultraviolet rays by combining an ultraviolet curable resin with an appropriately selected photoinitiator. Specifically, polyfunctional acrylates such as trimethylolpropane triacrylate and pentaerythritol tetraacrylate are used alone or in admixture of two or more thereof, and Irgacure 907 (manufactured by Ciba Specialty Chemicals) ), Irgacure 184 (manufactured by Ciba Specialty Chemicals), and a photopolymerization initiator such as Lucillin TPO (manufactured by BASF) can be suitably used.

  On the other hand, the hot embossing method is a method in which a transparent base material made of a thermoplastic resin is pressed against a mold in a heated state, and the surface uneven shape of the mold is transferred to the transparent base material. The transparent base material used in the hot embossing method may be any material as long as it is substantially transparent. For example, polymethyl methacrylate, polycarbonate, polyethylene terephthalate, triacetyl cellulose, norbornene compounds are used as monomers. A solvent cast film or an extruded film of a thermoplastic resin such as amorphous cyclic polyolefin can be used. These transparent resin films can also be suitably used as a transparent substrate for applying the ultraviolet curable resin in the UV embossing method described above.

<Method for producing mold for producing antiglare film>
Below, the manufacturing method of the metal mold | die which can be used suitably for the manufacturing method of the anti-glare film of this invention is demonstrated. FIG. 2 is a view schematically showing a preferred example of the first half of the mold manufacturing method of the present invention. In FIG. 2, the cross section of the metal mold | die in each process is shown typically. The mold manufacturing method of the present invention includes [1] a first plating step, [2] a polishing step, [3] a photosensitive resin film forming step, [4] an exposure step, and [5] a development step. [6] Basically includes a first etching step, [7] a photosensitive resin film peeling step, and [8] a second plating step. Hereafter, each process of the manufacturing method of the metal mold | die of this invention is demonstrated in detail, referring FIG.

[1] First Plating Step In the mold manufacturing method of the present invention, first, copper plating or nickel plating is applied to the surface of the substrate used for the mold. Thus, by performing copper plating or nickel plating on the surface of the mold base, it is possible to improve the adhesion and gloss of chromium plating in the subsequent second plating step. In other words, when chrome plating is applied to the surface of iron or the like, or when chrome plating is applied again after forming irregularities on the chrome plating surface by the sandblasting method or the bead shot method, the surface tends to be rough and fine cracks occur. This makes it difficult to control the uneven shape on the surface of the mold. On the other hand, such inconvenience can be eliminated by first performing copper plating or nickel plating on the substrate surface. This is because copper plating or nickel plating has a high covering property and a strong smoothing action, so that a flat and glossy surface is formed by filling minute irregularities and nests of the mold base. is there. Due to the characteristics of these copper plating or nickel plating, even if chromium plating is applied in the second plating step described later, the roughness of the chromium plating surface that seems to be caused by minute irregularities and nests existing on the base material is eliminated. In addition, the occurrence of fine cracks is reduced due to the high coverage of copper plating or nickel plating.

  The copper or nickel used in the first plating step may be a pure metal, or may be an alloy mainly composed of copper or an alloy mainly composed of nickel. “Copper” means to include copper and copper alloy, and “nickel” means to include nickel and nickel alloy. Copper plating and nickel plating may be performed by electrolytic plating or electroless plating, respectively, but electrolytic plating is usually employed.

  When copper plating or nickel plating is performed, if the plating layer is too thin, the influence of the underlying surface cannot be completely eliminated. Therefore, the thickness is preferably 50 μm or more. Although the upper limit of the plating layer thickness is not critical, the upper limit of the plating layer thickness is preferably about 500 μm in view of cost and the like.

  In the metal mold manufacturing method of the present invention, examples of the metal material suitably used for forming the metal mold substrate include aluminum and iron from the viewpoint of cost. From the viewpoint of handling convenience, it is more preferable to use lightweight aluminum. The aluminum and iron here may be pure metals, respectively, or may be an alloy mainly composed of aluminum or iron.

  Moreover, the shape of the mold base material may be an appropriate shape conventionally employed in the field, and may be, for example, a plate-like shape, a columnar shape, or a cylindrical roll. If a mold is produced using a roll-shaped substrate, there is an advantage that the antiglare film can be produced in a continuous roll shape.

[2] Polishing Step In the subsequent polishing step, the surface of the substrate that has been subjected to copper plating or nickel plating in the first plating step described above is polished. It is preferable that the base material surface is grind | polished in the state close | similar to a mirror surface through the said process. This is because metal plates and metal rolls that serve as base materials are often subjected to machining such as cutting and grinding in order to achieve the desired accuracy, and as a result, machine marks remain on the base material surface. This is because even if copper plating or nickel plating is applied, those processed marks may remain, and the surface may not be completely smooth in the plated state. That is, even if a process described later is performed on the surface where such deep processed marks remain, unevenness such as processed marks may be deeper than the unevenness formed after each process is performed. Such effects may remain, and when an antiglare film is produced using such a mold, the optical characteristics may be unexpectedly affected. In FIG. 2 (a), a plate-shaped mold substrate 7 is subjected to copper plating or nickel plating on the surface in the first plating step (for the copper plating or nickel plating layer formed in this step). Further, a state in which the surface 8 is mirror-polished by a polishing process is schematically shown.

  There is no particular limitation on the method for polishing the surface of the substrate on which copper plating or nickel plating has been applied, and any of mechanical polishing, electrolytic polishing, and chemical polishing can be used. Examples of the mechanical polishing method include super finishing, lapping, fluid polishing, and buff polishing. As for the surface roughness after polishing, the center line average roughness Ra in accordance with the provisions of JIS B 0601 is preferably 0.1 μm or less, and more preferably 0.05 μm or less. If the centerline average roughness Ra after polishing is greater than 0.1 μm, the final unevenness of the mold surface may remain affected by the surface roughness after polishing. In addition, the lower limit of the center line average roughness Ra is not particularly limited, and there is no limit in particular because there is a natural limit from the viewpoint of processing time and processing cost.

[3] Photosensitive resin film forming step In the subsequent photosensitive resin film forming step, the photosensitive resin was dissolved in the solvent on the polished surface 8 of the mold substrate 7 that was mirror-polished by the polishing step described above. A photosensitive resin film is formed by applying as a solution, heating and drying. FIG. 2B schematically shows a state where the photosensitive resin film 9 is formed on the polished surface 8 of the mold base 7.

  A conventionally known photosensitive resin can be used as the photosensitive resin. Examples of the negative photosensitive resin having a property of curing the photosensitive part include, for example, a monomer or prepolymer of an acrylate ester having an acrylic group or a methacrylic group in the molecule, a mixture of bisazide and a diene rubber, polyvinyl Cinnamate compounds and the like can be used. Further, as a positive photosensitive resin having such a property that a photosensitive part is eluted by development and only an unexposed part remains, for example, a phenol resin type or a novolac resin type can be used. Moreover, you may mix | blend various additives, such as a sensitizer, a development accelerator, an adhesiveness modifier, and a coating property improving agent, with a photosensitive resin as needed.

  When these photosensitive resins are applied to the polished surface 8 of the mold base 7, it is preferable to dilute and apply in an appropriate solvent in order to form a good coating film. As the solvent, cellosolve solvents, propylene glycol solvents, ester solvents, alcohol solvents, ketone solvents, highly polar solvents, and the like can be used.

  As a method for applying the photosensitive resin solution, known methods such as meniscus coating, fountain coating, dip coating, spin coating, roll coating, wire bar coating, air knife coating, blade coating, and curtain coating may be used. it can. The thickness of the coating film is preferably in the range of 1 to 6 μm after drying.

[4] Exposure Step In the subsequent exposure step, the gradation pattern described above is exposed on the photosensitive resin film 9 formed in the photosensitive resin film formation step described above. The light source used in the exposure process may be appropriately selected according to the photosensitive wavelength and sensitivity of the coated photosensitive resin. For example, the g-line (wavelength: 436 nm) of the high-pressure mercury lamp, the h-line (wavelength: 405 nm) of the high-pressure mercury lamp. ), I line (wavelength: 365 nm) of high pressure mercury lamp, semiconductor laser (wavelength: 830 nm, 532 nm, 488 nm, 405 nm, etc.), YAG laser (wavelength: 1064 nm), KrF excimer laser (wavelength: 248 nm), ArF excimer laser (wavelength) 193 nm), F2 excimer laser (wavelength: 157 nm), or the like.

  In order to form the surface uneven shape with high accuracy in the mold manufacturing method of the present invention, it is preferable to expose the gradation pattern on the photosensitive resin film in a precisely controlled manner in the exposure step. In the mold manufacturing method of the present invention, in order to accurately expose the gradation pattern on the photosensitive resin film, a laser controlled by a computer based on the gradation pattern which is image data created by a computer. It is preferable to draw a pattern on the photosensitive resin film with a laser beam emitted from the head. When performing such laser drawing, a laser drawing apparatus for making a printing plate can be used. Examples of such a laser drawing apparatus include Laser Stream FX (manufactured by Sink Laboratory Co., Ltd.) and the like.

  FIG. 2C schematically shows a state in which the pattern is exposed on the photosensitive resin film 9. When the photosensitive resin film is formed of a negative photosensitive resin, the exposed region 10 undergoes a crosslinking reaction of the resin by exposure, and the solubility in a developing solution described later decreases. Therefore, the unexposed area 11 in the developing process is dissolved by the developer, and only the exposed area 10 remains on the substrate surface as a mask. On the other hand, in the case where the photosensitive resin film is formed of a positive photosensitive resin, the exposed region 10 is cut by bonding of the resin by exposure, and the solubility in a developer described later increases. Therefore, the area 10 exposed in the development process is dissolved by the developer, and only the unexposed area 11 remains on the substrate surface as a mask.

[5] Development Step In the subsequent development step, when a negative photosensitive resin is used for the photosensitive resin film 9, the unexposed region 11 is dissolved by the developer, and only the exposed region 10 is gold. It remains on the mold substrate and acts as a mask in the subsequent first etching step. On the other hand, when a positive photosensitive resin is used for the photosensitive resin film 9, only the exposed region 10 is dissolved by the developer, and the unexposed region 11 remains on the mold substrate. It acts as a mask in the subsequent first etching step.

  A conventionally well-known thing can be used about the developing solution used for a image development process. For example, inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, primary amines such as ethylamine and n-propylamine, diethylamine, di-n-butylamine and the like Secondary amines, tertiary amines such as triethylamine, methyldiethylamine, alcohol amines such as dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethylhydroxyethylammonium hydroxide, etc. Examples include alkaline aqueous solutions such as quaternary ammonium salts, cyclic amines such as pyrrole and piperidine; and organic solvents such as xylene and toluene.

  The development method in the development step is not particularly limited, and methods such as immersion development, spray development, brush development, and ultrasonic development can be used.

  FIG. 2D schematically shows a state in which development processing is performed using a negative photosensitive resin for the photosensitive resin film 9. In FIG. 2C, the unexposed area 11 is dissolved by the developing solution, and only the exposed area 10 becomes the remaining mask 12 on the substrate surface. FIG. 2E schematically shows a state where development processing is performed using a positive photosensitive resin for the photosensitive resin film 9. In FIG. 2C, the exposed area 10 is dissolved by the developer, and only the unexposed area 11 becomes the remaining mask 12 on the substrate surface.

[6] First Etching Step In the subsequent first etching step, the mold base is mainly used in a portion where there is no mask, using the photosensitive resin film remaining on the mold base surface after the development step as a mask. The material is etched to form irregularities on the polished plated surface. FIG. 3 is a diagram schematically showing a preferred example of the latter half of the method for producing a mold of the present invention. FIG. 3A schematically shows a state in which the mold base 7 in the portion 13 where no mask is mainly etched by the first etching step. The mold base 7 below the mask 12 is not etched from the mold base surface, but etching from the portion 13 without the mask proceeds with the progress of etching. Therefore, in the vicinity of the boundary between the mask 12 and the portion 13 without the mask, the mold base 7 under the mask 12 is also etched. In the vicinity of the boundary between the mask 12 and the portion 13 without the mask, the die base material 7 below the mask 12 is also etched, which is hereinafter referred to as side etching. FIG. 4 schematically shows the progress of side etching. The dotted line 14 in FIG. 4 shows the surface of the mold base material that changes with the progress of etching in stages.

The etching process in the first etching step is usually performed using a ferric chloride (FeCl ₃ ) solution, a cupric chloride (CuCl ₂ ) solution, an alkali etching solution (Cu (NH ₃ ) ₄ Cl ₂ ), etc. Although it is performed by corroding the surface, a strong acid such as hydrochloric acid or sulfuric acid can be used, or reverse electrolytic etching by applying a potential opposite to that during electrolytic plating can also be used. The concave shape formed on the mold base material when the etching process is performed differs depending on the type of the base metal, the type of the photosensitive resin film, the etching technique, and the like. In the following cases, the etching is performed isotropically from the metal surface in contact with the etching solution. The etching amount here is the thickness of the base material to be cut by etching.

  The etching amount in the first etching step is preferably 1 to 50 μm. When the etching amount is less than 1 μm, the unevenness shape is hardly formed on the metal surface, and the die is almost flat, so that the antiglare property is not exhibited. In addition, when the etching amount exceeds 50 μm, the height difference of the concavo-convex shape formed on the metal surface becomes large, and in the image display device to which the antiglare film produced using the obtained mold is applied, it is white. There is a risk of injury. The etching process in the first etching step may be performed by one etching process, or the etching process may be performed twice or more. In the case where the etching process is performed twice or more, the total etching amount in the two or more etching processes is preferably 1 to 50 μm.

[7] Photosensitive resin film peeling step In the subsequent photosensitive resin film peeling step, the remaining photosensitive resin film used as a mask in the first etching step is completely dissolved and removed. In the photosensitive resin film peeling step, the photosensitive resin film is dissolved using a peeling solution. As the stripper, the same developer as that described above can be used. When a negative photosensitive resin film is used by changing pH, temperature, concentration, immersion time, etc., the exposed portion is exposed. When the positive photosensitive resin film is used, the photosensitive resin film in the non-exposed portion is completely dissolved and removed. There is no particular limitation on the peeling method in the photosensitive resin film peeling step, and methods such as immersion development, spray development, brush development, and ultrasonic development can be used.

  FIG. 3B schematically shows a state where the photosensitive resin film used as the mask 12 in the first etching process is completely dissolved and removed by the photosensitive resin film peeling process. The first surface irregularities 15 are formed on the surface of the mold substrate by etching using the mask 12 made of a photosensitive resin film.

[8] Second plating step Subsequently, the surface unevenness shape is blunted by performing chromium plating on the formed uneven surface (first surface unevenness shape 15). In FIG. 3 (c), by forming the chromium plating layer 16 on the first surface uneven shape 15 formed by the etching process of the first etching step, the unevenness is duller than the first surface uneven shape 15. The state where the surface (the surface 17 of chrome plating) is formed is shown.

In the present invention, chrome plating is employed which has a glossy surface, a high hardness, a low coefficient of friction, and good release properties on the surface of a flat plate or a roll. The type of chrome plating is not particularly limited, but it is preferable to use a chrome plating that expresses a good gloss, so-called gloss chrome plating or decorative chrome plating. Chromium plating is usually performed by electrolysis, and an aqueous solution containing chromic anhydride (CrO ₃ ) and a small amount of sulfuric acid is used as the plating bath. By adjusting the current density and electrolysis time, the thickness of the chromium plating can be controlled.

  JP-A-2002-189106, JP-A-2004-45472, JP-A-2004-90187, and the like disclosed above employ chrome plating. Depending on the type of chrome plating, the surface is often roughened after plating, or many fine cracks due to chrome plating often occur, and as a result, the optical properties of the antiglare film obtained using the mold are undesirable. Proceed with A mold having a rough plated surface is not suitable for producing an antiglare film. This is because the plating surface is generally polished after chrome plating in order to eliminate roughness, but as described later, polishing of the surface after plating is not preferable in the present invention. In the present invention, by applying copper plating or nickel plating to the base metal, such an inconvenience easily caused by chromium plating is solved.

  In the second plating step, it is not preferable to perform plating other than chromium plating. This is because plating other than chromium has low hardness and wear resistance, so that the durability as a mold is lowered, and unevenness is worn away during use or the mold is damaged. In an antiglare film obtained from such a mold, there is a high possibility that a sufficient antiglare function cannot be obtained, and there is a high possibility that defects will occur on the film.

  Further, the surface polishing after plating as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2004-90187 is also not preferable in the present invention. That is, it is preferable to use the concavo-convex surface subjected to chrome plating as the concavo-convex surface of the mold transferred onto the transparent substrate without providing a step of polishing the surface after the second plating step. By polishing, a flat part is generated on the outermost surface, which may lead to deterioration of optical characteristics, and since shape control factors increase, shape control with good reproducibility becomes difficult. Depending on the reason.

  In this way, in the mold manufacturing method of the present invention, a chrome plating is applied to the surface on which the fine surface irregularities are formed, whereby a mold having an irregular surface and a higher surface hardness can be obtained. . The bluntness of the irregularities at this time varies depending on the type of the base metal, the size and depth of the irregularities obtained from the first etching process, and the type and thickness of the plating. The greatest factor in controlling is the plating thickness. If the thickness of the chrome plating is thin, the effect of dulling the surface shape of the unevenness obtained before the chrome plating process is insufficient, and the optical characteristics of the antiglare film obtained by transferring the uneven shape onto a transparent substrate Is not so good. On the other hand, when the plating thickness is too thick, productivity is deteriorated and a projection-like plating defect called a nodule is generated, which is not preferable. Therefore, the thickness of the chrome plating is preferably in the range of 1 to 10 μm, and more preferably in the range of 3 to 6 μm.

  The chromium plating layer formed in the second plating step is preferably formed to have a Vickers hardness of 800 or more, and more preferably 1000 or more. When the Vickers hardness of the chrome plating layer is less than 800, the durability when using the mold is reduced, and the decrease in hardness due to chrome plating is due to abnormalities in the plating bath composition, electrolysis conditions, etc. during the plating process. This is because the possibility of occurrence is high, and the possibility of undesirably affecting the occurrence of defects is also high.

  Moreover, in the manufacturing method of the metal mold | die of this invention, the uneven | corrugated surface formed by the 1st etching process is etched between the above-mentioned [7] photosensitive resin film peeling process and [8] 2nd plating process. It is preferable to include the 2nd etching process blunted by. In the second etching process, the first surface irregularities 15 formed by the first etching process using the photosensitive resin film as a mask are blunted by an etching process. By this second etching process, there is no portion with a steep surface inclination in the first surface irregularity shape 15 formed by the first etching process, and the optical characteristics of the antiglare film manufactured using the obtained mold are reduced. It changes in the preferred direction. In FIG. 5, the first surface irregularity shape 15 of the mold base 7 is blunted by the second etching process, the portion having a steep surface inclination is blunted, and the second surface irregularity having a gentle surface inclination is obtained. The state where the shape 18 is formed is shown.

Similarly to the first etching step, the etching process in the second etching step is usually ferric chloride (FeCl ₃ ) solution, cupric chloride (CuCl ₂ ) solution, alkaline etching solution (Cu (NH ₃ ) ₄ Cl ₂ ) or the like, and by corroding the surface, strong acid such as hydrochloric acid or sulfuric acid can be used, or reverse electrolytic etching by applying a potential opposite to that during electrolytic plating can also be used. The bluntness of the unevenness after the etching process varies depending on the type of the underlying metal, the etching technique, and the size and depth of the unevenness obtained by the first etching process. The largest factor in controlling the amount is the etching amount. The etching amount here is also the thickness of the base material to be cut by etching, as in the first etching step. When the etching amount is small, the effect of dulling the surface shape of the unevenness obtained by the first etching process is insufficient, and the optical characteristics of the antiglare film obtained by transferring the uneven shape onto the transparent substrate are not so much. It doesn't get better. On the other hand, when the etching amount is too large, the uneven shape is almost lost and the die is almost flat, so that the antiglare property is not exhibited. Therefore, the etching amount is preferably in the range of 1 to 50 μm, and more preferably in the range of 4 to 20 μm. Similarly to the first etching process, the etching process in the second etching process may be performed by one etching process, or the etching process may be performed twice or more. In the case where the etching process is performed twice or more, the total etching amount in the two or more etching processes is preferably 1 to 50 μm.

  By using the mold obtained by the mold manufacturing method of the present invention, the fine uneven surface shape is accurately controlled and formed, so that sufficient anti-glare property is exhibited and whitish does not occur. Even when it is arranged on the surface of the image display device, glare does not occur, and an antiglare film showing high contrast can be obtained. Furthermore, it is possible to obtain an antiglare film in which the occurrence of interference colors, moire and repeated patterns are effectively suppressed.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

[1] Measurement of spatial frequency indicating maximum value of energy spectrum of gradation pattern The created gradation pattern data is converted to grayscale image data of 256 gradations at 12800 dpi, and gradation is converted into a two-dimensional discrete function g (x, y). The resulting two-dimensional discrete function g (x, y) and by discrete Fourier transform, two-dimensional function G (f _x, f _y) was determined. Two-dimensional function G (f _x, f _y) a two-dimensional function ^{_{G 2 (f x, f y}} ) of energy spectrum was calculated by squaring, G ² (0 is a cross-sectional curve of f _x = 0, f _y ) [A two-dimensional graph in which the horizontal axis is the spatial frequency fy and the vertical axis is the energy spectrum), the spatial frequency indicating the maximum value of the energy spectrum was obtained. Here, in the “spatial frequency indicating the maximum value of the energy spectrum” shown in Table 1 below, the spatial frequency having the smallest absolute value among a plurality of maximum values existing at positions other than the position of the spatial frequency f _y = 0 μm ^−1. The spatial frequency corresponding to the maximum value indicating the maximum value is described. The horizontal resolution of the pattern used for the calculation was set to 2 μm for both Δx and Δy. The calculation range was 1000 μm × 1000 μm.

[2] Measurement of haze of antiglare film The haze of the antiglare film was measured by a method defined in JIS K7136. Specifically, haze was measured using a haze meter HM-150 type (manufactured by Murakami Color Research Laboratory) compliant with this standard. In order to prevent the anti-glare film from warping, it was subjected to measurement after being bonded to a glass substrate using an optically transparent pressure-sensitive adhesive so that the uneven surface becomes the surface. In general, when haze increases, an image becomes dark when applied to an image display device, and as a result, front contrast tends to decrease. Therefore, a lower haze is preferable.

[3] Evaluation of anti-glare performance of anti-glare film (Repeated pattern, interference color, reflection, visual evaluation of whitishness)
In order to prevent reflection from the back surface of the antiglare film, the antiglare film is bonded to the black acrylic resin plate so that the uneven surface becomes the surface, and visually observed from the uneven surface side in a bright room with a fluorescent lamp. Then, the presence or absence of repeated patterns, the presence or absence of interference colors, the presence or absence of reflection of a fluorescent lamp, and the presence or absence of whitishness were evaluated visually. Repetitive patterns, interference colors, reflections, and whitishness were evaluated according to the following criteria in three stages of 1 to 3, respectively.

Repeat pattern 1: No repeat pattern is observed.
2: A repetitive pattern is observed a little.

3: Repeated pattern is clearly observed.
Interference color 1: No interference color is observed.

2: A little interference color is observed.
3: Interference color is clearly observed.

Reflection 1: Reflection is not observed.
2: Reflection is slightly observed.

3: Reflection is clearly observed.
Whiteness 1: No whiteness is observed.

2: A little whitish is observed.
3: The whitish is clearly observed.

(Evaluation of glare and moire)
The polarizing plates on both the front and back sides were peeled off from a commercially available liquid crystal television (LC-32GH3 (manufactured by Sharp Corporation). Instead of these original polarizing plates, the polarizing plate Sumikaran SRDB31E (Sumitomo Chemical Co., Ltd.) was used on both the back side and the display side. )) Is bonded via an adhesive so that each absorption axis coincides with the absorption axis of the original polarizing plate, and on the display surface side polarizing plate, the antiglare shown in the following examples The film was pasted through an adhesive so that the uneven surface became the surface, and in this state, by visually observing from a position about 30 cm away from the sample, the degree of glare and moire was determined in the following three steps. It was evaluated by.

Glare 1: No glare is observed.
2: A little glare is observed.

3: Glare is clearly observed.
Moire 1: Moire is not observed.

2: Moire is slightly observed.
3: Moire is clearly observed.

<Example 1>
An aluminum roll having a diameter of 200 mm (A5056 according to JIS) was prepared by applying copper ballad plating to the surface. Copper ballad plating consists of a copper plating layer / thin silver plating layer / surface copper plating layer, and the thickness of the entire plating layer was set to be about 200 μm. The copper plating surface was mirror-polished, and a photosensitive resin was applied to the polished copper plating surface and dried to form a photosensitive resin film. Next, pattern data obtained by continuously and repeatedly arranging a plurality of gradation pattern data shown in FIG. 1 was exposed on a photosensitive resin film with a laser beam and developed. Laser light exposure and development were performed using Laser Stream FX (manufactured by Sink Laboratories). A positive photosensitive resin was used for the photosensitive resin film. The gradation pattern data shown in FIG. 1 is a pattern in which a large number of dots having a dot diameter (dot diameter) of 16 μm are randomly arranged, and the energy spectrum has a maximum value at a spatial frequency of 0.046 μm ⁻¹ . The gradation pattern data shown in FIG. 1 was created as a square with a side of 20 mm.

  Then, the 1st etching process was performed with the cupric chloride liquid. The etching amount at that time was set to 3 μm. The photosensitive resin film was removed from the roll after the first etching treatment, and the second etching treatment was performed again with cupric chloride solution. The etching amount at that time was set to 10 μm. Then, the chrome plating process was performed and the metal mold | die A was produced. At this time, the chromium plating thickness was set to 4 μm.

A photocurable resin composition GRANDIC 806T (manufactured by Dainippon Ink & Chemicals, Inc.) is dissolved in ethyl acetate to obtain a 50% strength by weight solution. Chemical name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) was added in an amount of 5 parts by weight per 100 parts by weight of the curable resin component to prepare a coating solution. This coating solution was applied onto a triacetyl cellulose (TAC) film having a thickness of 80 μm so that the coating thickness after drying was 10 μm, and was dried in a dryer set at 60 ° C. for 3 minutes. The film after drying was brought into close contact with the concavo-convex surface of the mold A obtained previously with a rubber roll so that the photocurable resin composition layer was on the mold side. In this state, light from a high-pressure mercury lamp with an intensity of 20 mW / cm ² was irradiated from the TAC film side so that the amount of light in terms of h-line was 200 mJ / cm ² to cure the photocurable resin composition layer. Thereafter, the TAC film was peeled from the mold together with the cured resin, and a transparent anti-glare film A composed of a laminate of the cured resin having irregularities on the surface and the TAC film was produced.

<Example 2>
The gray scale pattern shown in FIG. 6 is used as the gray scale pattern exposed by the laser beam, and the first etching process and the second etching process are performed with the etching amounts shown in Table 1 as in Example 1. Similarly, a mold B was obtained. An antiglare film B was produced in the same manner as in Example 1 except that the obtained mold B was used. The gradation pattern data shown in FIG. 6 is a pattern in which a large number of dots having a dot diameter of 12 μm are randomly arranged, and the energy spectrum has a maximum value at a spatial frequency of 0.056 μm ⁻¹ . The gradation pattern data shown in FIG. 6 was created as a square with a side of 100 mm.

<Example 3>
Etching amount described in Table 1 using the same gradation pattern as that used in Example 1 except that the pattern data was created as a square having a side length of 16 mm as a gradation pattern to be exposed by laser light. A mold C was obtained in the same manner as in Example 1 except that the first etching process and the second etching process were performed. An antiglare film C was produced in the same manner as in Example 1 except that the obtained mold C was used.

<Comparative Example 1 and Comparative Example 2>
As the gradation pattern exposed by the laser beam, the gradation pattern data shown in FIG. 7 created as a square having a side length of 20 mm is used, and the first etching process and the second etching are performed with the etching amounts shown in Table 1. A mold D and a mold E were obtained in the same manner as in Example 1 except that the etching process was performed. An antiglare film D and an antiglare film E were produced in the same manner as in Example 1 except that the obtained mold D and mold E were used. The gradation pattern data shown in FIG. 7 is a pattern in which a large number of dots having a dot diameter of 36 μm are randomly arranged, and the energy spectrum has a maximum value at a spatial frequency of 0.017 μm ⁻¹ . The energy spectrum of the gradation pattern data shown in FIG. 7 does not have a maximum value in the spatial frequency range of 0.025 to 0.125 μm ⁻¹ .

<Comparative Example 3>
A mold F was obtained in the same manner as in Comparative Example 1 except that the gradation pattern data shown in FIG. 7 created as a square having a side length of 10 mm was used as the gradation pattern exposed by the laser beam. . An antiglare film F was produced in the same manner as in Comparative Example 1 except that the obtained mold F was used.

<Comparative Examples 4-7>
As the gradation pattern to be exposed by laser light, the gradation patterns shown in FIGS. 8 to 11 were used, respectively, except that the first etching process and the second etching process were performed with the etching amounts shown in Table 1. In the same manner as in Example 1, molds G to J were obtained. Antiglare films G to J were produced in the same manner as in Example 1 except that the obtained molds G to J were used. The gradation pattern data shown in FIG. 8 is a pattern in which a large number of dots having a dot diameter of 16 μm are randomly arranged, and the energy spectrum has a maximum value at a spatial frequency of 0.056 μm ⁻¹ . The gradation pattern data shown in FIG. 8 was created as a square with a side of 10 mm. The gradation pattern data shown in FIG. 9 is a pattern in which a large number of three types of dots having a dot diameter of 14 μm, 18 μm, and 22 μm are randomly arranged, and the energy spectrum has a maximum value at a spatial frequency of 0.042 μm ⁻¹ . The gradation pattern data shown in FIG. 9 was created as a square with a side of 2 mm. The gradation pattern data shown in FIG. 10 is a pattern in which a large number of dots with a dot diameter of 20 μm are randomly arranged, and the energy spectrum has a maximum value at a spatial frequency of 0.033 μm ⁻¹ . Further, the gradation pattern data shown in FIG. 10 was created as a square having a side of 1 mm. The gradation pattern data shown in FIG. 11 is a pattern in which a large number of dots having a dot diameter of 22 μm are randomly arranged, and the energy spectrum has a maximum value at a spatial frequency of 0.033 μm ⁻¹ . The gradation pattern data shown in FIG. 11 was created as a square having a side of 1 mm.

Spatial frequency (as described above) indicating the etching amount of the first etching process and the second etching process when the molds A to J are manufactured, the dot diameter of the gradation pattern used for the manufacture, and the maximum value of the energy spectrum The spatial frequency described in this column is the spatial frequency f _y = 0 μm ^{− in} G ² (0, f _y ), which is a cross-sectional curve of f _x = 0 of the energy spectrum G ² (f _x , f _y ). Among a plurality of local maximum values other than position ¹ , the absolute value is the local frequency at which the absolute value indicates the local maximum, and the shape of the gradation pattern and the minimum length of one side Are summarized in Table 1. Further, FIG. 12, Example 1 illustrates a cross section taken along f _x = 0 Example 2 is calculated from the gradation pattern used for the energy spectrum ^{_{G 2 (f x, f y}} ). Figures horizontal axis of FIG. 12 shows the absolute value of the spatial frequency f _y.

  Moreover, in Table 2, the measurement result of the haze of the obtained anti-glare film and the evaluation result of anti-glare performance are shown.

From the evaluation results in Table 2, the antiglare films A to C of Examples 1 to 3 obtained by the production method of the present invention have a minimum length of one side of 15 mm or more, and the energy spectrum has a spatial frequency of 0. Since a mold is produced using a gradation pattern having a maximum value within a range of .025 to 0.125 μm ⁻¹ , and the uneven surface of the obtained mold is transferred to form a fine uneven surface, It can be seen that the anti-glare film has excellent visibility, and is excellent in anti-reflection performance, and has no visibility of glare, whitish, repeated patterns, interference colors, and moire. Moreover, since the anti-glare films A to C exhibit good anti-glare performance while having low haze, it is possible to provide an image display device that exhibits excellent anti-glare properties but exhibits high contrast. .

On the other hand, in the anti-glare films D and E of Comparative Examples 1 and 2, since the minimum length of one side of the used gradation pattern was 20 mm, interference color and moire did not occur, but the energy spectrum was spatial. to show no maximum in the range of frequencies 0.025~0.125μm ^-1, the effect of suppressing glare and Shirochake is not sufficient. In addition, by using a gradation pattern whose energy spectrum does not show a maximum value within the above range, a repetitive pattern (a grid-like line constituting the contour of the uneven surface unit corresponding to the repetitively arranged gradation pattern) Was observed.

Further, in the antiglare films F to J of Comparative Examples 3 to 7, since the minimum side length of the used gradation pattern is 1 to 10 mm, the energy spectrum has a spatial frequency of 0.025 to 0.125 μm ^−. Even in the case where the maximum value was exhibited within the range of ¹ , a repetitive pattern was observed. In addition, in the antiglare films H to J of Comparative Examples 5 to 7 in which the minimum side length of the used gradation pattern was less than 10 mm, interference colors and moire were also observed. Further, in the antiglare film F of Comparative Example 3, the glare was observed because the energy spectrum of the gradation pattern used did not show a maximum value within the spatial frequency range of 0.025 to 0.125 μm ⁻¹ . .

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  7 substrate for mold, 8 surface of substrate polished by polishing process, 9 photosensitive resin film, 10 photosensitive resin film exposed in exposure process, 11 photosensitive resin film not exposed in exposure process, 12 mask , 13 Location without mask, 14 Surface formed stepwise by etching, 15 Substrate surface after first etching step (first surface irregular shape), 16 Chromium plating layer, 17 Chromium plating surface, 18th 2 Substrate surface after the etching step (second surface irregular shape).

Claims (10)

Including a step of forming an uneven surface on a transparent substrate using a gradation pattern;
The gradation pattern has a minimum length of one side of 15 mm or more, and the energy spectrum of the gradation pattern exhibits a maximum value within a spatial frequency range of 0.025 to 0.125 μm ⁻¹ .
The method for producing an antiglare film, wherein the concavo-convex surface is composed of a repetitive structure of concavo-convex surface units composed of concave portions and convex portions corresponding to the gradation of the gradation pattern. The gradation pattern is image data binarized into white and black,
2. The method for producing an antiglare film according to claim 1, wherein any one of a concave portion and a convex portion constituting the uneven surface unit corresponds to a white region of the binarized image data.   The step of forming the concavo-convex surface on the transparent substrate includes a step of producing a mold having a concavo-convex surface using the gradation pattern and transferring the concavo-convex surface of the mold onto the transparent substrate. The manufacturing method of the anti-glare film of Claim 1 or 2. A method for producing the mold according to claim 3,
A first plating step of performing copper plating or nickel plating on the surface of the mold base;
A polishing step of polishing the surface plated by the first plating step;
A photosensitive resin film forming step of forming a photosensitive resin film on the polished surface;
An exposure step of exposing the gradation pattern on the photosensitive resin film;
A developing step of developing the photosensitive resin film exposed to the gradation pattern;
A first etching step of performing an etching process using the developed photosensitive resin film as a mask and forming irregularities on the polished plated surface;
A photosensitive resin film peeling step for peeling the photosensitive resin film;
A second plating step of applying chromium plating to the formed uneven surface;
A method for manufacturing a mold, including:   The manufacturing method of the metal mold | die of Claim 4 including the 2nd etching process of blunting the uneven | corrugated shape of the formed uneven surface by an etching process between the said photosensitive resin film peeling process and the said 2nd plating process. .   The mold manufacturing method according to claim 4 or 5, wherein the concavo-convex surface formed with chromium plating in the second plating step is a concavo-convex surface of a mold transferred onto the transparent substrate.   The manufacturing method of the metal mold | die in any one of Claims 4-6 in which the chromium plating layer formed by the chromium plating in a said 2nd plating process has a thickness of 1-10 micrometers.   The anti-glare film manufactured by the manufacturing method in any one of Claims 1-3. It is a gradation pattern used for the manufacturing method of the anti-glare film according to claim 1,
A gradation pattern in which the minimum length of one side is 15 mm or more and the energy spectrum shows a maximum value in the range of the spatial frequency of 0.025 to 0.125 μm ⁻¹ .   The gradation pattern according to claim 9, which is image data binarized into white and black.

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