KR101189305B1 - Method for Manufacturing Anti-glare Film - Google Patents

Abstract

The present invention provides an anti-glare film and a method of manufacturing the same, which realize the reduction of the glare of the screen without sacrificing anti-glare property, and provide an image display device having excellent visibility by using the same.
As an anti-glare film in which fine irregularities are formed on the surface, the area higher than the average height of the unevenness is convex, and the area lower than the average height of the unevenness is concave, and the projection area of the individual convex or the projection area of the concave is determined to obtain a predetermined area. by obtaining the frequency of the convex ttoeun recess, also when calculating the frequency of the apparent surface area by the predetermined area by the area × frequency, and displays the frequency of the apparent surface area of the obtained convex or concave as a bar graph, the peak value is 300 ㎛ ² The anti-glare film 20 which appears in the following position and whose half value width of the peak is 60 micrometer <^2> or less is provided. This anti-glare film 20 is arrange | positioned at the visual recognition side of image display means, such as a liquid crystal panel, and an image display apparatus is comprised.
A lithography step of forming irregularities in the photoresist film 12 formed on the substrate 11 by photolithography, and electroforming the metal 17 on the uneven surface of the obtained photoresist film to form an uneven shape. After the transfer to (17), the metal plate 17 to which the uneven shape has been transferred is peeled from the photoresist film 13 and the die 18 is manufactured. ) Is used as a mold and the anti-glare film 20 having unevenness on the surface is subjected to the uneven film manufacturing process of transferring the uneven shape of the surface to the surface of the film 20. This is performed by exposing and subsequently developing the photoresist film 12 through the photomask 14 having two or more kinds of patterns.

Description

Method for manufacturing anti-glare film {Method for Manufacturing Anti-glare Film}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antiglare film suitably used for optical applications such as a polarizing film in an image display device. Particularly, even when applied to an image display device with high precision, it is difficult to cause sparkling and the like, and to ensure high visibility. It relates to an anti-glare film that can be. The present invention also relates to an image display device using such an antiglare film.

Moreover, this invention relates to the manufacturing method of the anti-glare film used suitably for optical uses, such as a polarizing film in an image display apparatus. Specifically, it relates to a preferred method for making antiglare films effective for obtaining a particular reflection profile.

In an image display device including a liquid crystal display device, visibility is remarkably impaired when external light is projected onto the image display surface. Applications such as televisions and personal computers, which focus on image quality, video cameras and digital cameras used outdoors with strong external light, and reflection type liquid crystal displays such as mobile phones that display using reflected light. It is a typical example that the treatment for preventing such projection is performed on the surface of the display device. Projection prevention processing is roughly divided into antireflection processing using interference by an optical multilayer film, and so-called anti-glare processing that scatters incident light by blurring incident light by forming fine irregularities on the surface. The former non-reflective treatment needs to form a multilayer film having a uniform optical film thickness, and thus has a problem of being expensive. On the other hand, the latter antiglare treatment can be realized at a relatively low cost, and therefore, it is used for a large personal computer, a monitor, or the like.

The anti-glare film is, for example, coated with a UV curable resin in which a filler is dispersed on a transparent substrate, dried, and then irradiated with UV light to cure the resin to form random irregularities on the film surface. It is manufactured by. And many proposals to provide anti-glare property by forming fine unevenness | corrugation on the surface of the film used for an image display apparatus until now are made | formed. For example, Japanese Patent Laid-Open No. 2003-4903 discloses an antiglare film having an antiglare layer on a transparent support and having concave and convex on its surface, wherein an antiglare film having an area of a cut surface of each concave is 1, OO μm ² or less. The ultraviolet-ray curable resin which disperse | distributed the particle | grains of the average particle diameter of 0.2-10 micrometers was apply | coated on this transparent support body, and ultraviolet-cured to produce the anti-glare film which has the said unevenness | corrugation here.

On the other hand, in Japanese Unexamined Patent Application Publication No. 6-16851 and Japanese Unexamined Patent Application Publication No. 7-124969, a transparent base material having an ultraviolet curable resin layer is in close contact with a film to which a concave-convex shape is given in advance on the ultraviolet curable resin layer side. The method of irradiating an ultraviolet-ray to this ultraviolet curable resin layer and transferring an uneven | corrugated shape to ultraviolet curable resin is disclosed. However, as a film to which the uneven | corrugated shape was previously given, Unexamined-Japanese-Patent No. 6-16851 discloses only apply | coating the resin composition containing a filler and a binder on a base film, Unexamined-Japanese-Patent No. 7-124969. It only discloses the method of extending | stretching the film which added the filler internally, and the method of sandblasting a film afterwards.

Japanese Unexamined Patent Application Publication No. 2002-365410 discloses an optical film having fine irregularities formed on a surface thereof, wherein when light is incident on the surface of the film in the direction of -10 ° with respect to the normal line, only the reflected light on the surface is observed. An antiglare film is disclosed in which a profile of reflected light satisfies a specific relationship.

Japanese Unexamined Patent Publication No. 2003-177207 assumes that a multi-layered antireflection layer is provided on the uneven surface, but an uneven surface having an average height Rc of the contour curve element of 0.1 to 30 µm is formed. Of O.01 mm ² An antireflection film having a resin layer having a number of convex portions of sugar of 1 to 1000, wherein a parallel plane having an inclination angle of 0 to 5 ° with respect to the antireflection film surface of the uneven surface occupies 15 to 100%, and 15 to 100 of the parallel plane. The antireflection film in which% is formed in the convex part is disclosed. Although this patent document uses the mat shaping film in order to form such an unevenness | corrugation, the specific manufacturing method of this mat shaping film is not shown.

In the conventionally known anti-glare film, in particular, the anti-glare film obtained by dispersing the filler, since the filler is randomly disposed upon application, the density distribution of the filler, and furthermore, the density distribution of irregularities formed on the surface has occurred. Also. In industrial production, agglomeration of a filler is likely to occur, and staining and the like may occur due to this.

When using such a conventional anti-glare film in combination with a high-precision liquid crystal panel, although the cause is not clear, it was difficult to say that a display looked shiny and sufficient visibility was obtained. In order to make the density distribution of unevenness | corrugation small, what is necessary is just to reduce the compounding quantity of a filler, but in this case, sufficient anti-glare property is not obtained. On the other hand, when the compounding quantity of a filler is too large, anti-glare property is obtained, but there existed a problem that opacity became high and contrast was low.

On the other hand, as an anti-glare film used for an image display apparatus, since it is preferable that a some unevenness | corrugation exists in one pixel, the magnitude | size of each unevenness | corrugation needs to be made smaller than the size of the pixel of the image display apparatus to apply. And it is necessary to design the shape and arrangement of the unevenness so that the reflection of the light by the unevenness of this size is optimal, but at that time, the size of the geometrical optical element and unevenness by the shape of the unevenness in the reflected light It is necessary to consider wave optical elements such as light interference or diffraction due to small things. For example, in an antiglare film that can correspond to an image display device such as a liquid crystal display device or a plasma display panel, in the case where irregularities having the same size are randomly arranged from several micrometers to several tens of micrometers, the size of the unevenness is the same. This results in interference or diffraction due to this, which results in a problem that the reflected light due to irregularities on the surface appears to be iridescent, or the reflected light is strongly visible at a certain reflection angle.

The inventors of Japanese Patent Application No. 2004-4308 (Priority claim: Japanese Patent Application No. 2003-8744) provide a step of forming irregularities by photolithography on a photoresist formed on a substrate, and a metal on the uneven surface of the obtained photoresist. After casting, the metal is peeled from the photoresist to transfer the concave-convex shape on the photoresist to the metal, and the concave-convex portion metal plate is used as a mold, and the concave-convex surface is transferred to the film surface. The method of manufacturing an anti-glare film is proposed.

This invention is made | formed in view of such a phenomenon, The objective is to provide the anti-glare film which realized the reduction of the glare of a screen, without sacrificing anti-glare property. It is still another object of the present invention to provide an image display apparatus which is excellent in visibility without glare of a screen by using such an antiglare film.

Still another object of the present invention is to provide a method of controlling the irregularities formed on the surface and producing an antiglare film having excellent optical characteristics.

As a result of earnestly researching for this purpose, the present inventors have found that the density distribution of unevenness in the unevenly formed film has a great influence on the performance of the sparkling, and found that a high-performance antiglare film can be obtained by controlling it appropriately. Further, various studies have been added to complete the present invention. Further, based on the method proposed in Japanese Patent Application No. 2004-4308, it was found that a high-performance anti-glare film is obtained by studying a photomask in a step of forming irregularities by photolithography.

That is, according to the present invention, fine unevenness is formed on the surface, convex in the area higher than the average height of the unevenness, concave in the area lower than the average height of the unevenness, and the projection area of each convex or the projected area of the concave is obtained, The peak value when the frequency of the apparent area of the convex or concave obtained by calculating the frequency of the convex or concave for each predetermined area and calculating the frequency of the apparent area for each of the predetermined area based on the area x frequency. Appears at a position of 300 μm ² or less, and an antiglare film having a half width of the peak of 60 μm ² or less is provided.

As for the said peak value, it is more preferable to appear in the position of 150 micrometer <^2> or less. In addition, it is preferable to make the half value width of the said peak larger than 10 micrometer <^2> .

It is advantageous that such anti-glare film has a reflectance of 0.001% or less in the direction twisted by 20 degrees from the specular reflection angle. In addition, it is advantageous to make the 45 ° reflection clarity measured by the optical body of 1.0 mm the width | variety of a dark part and a ridge | curd become 50% or less. In addition, it is advantageous that the total value of the transmission clarity measured using four kinds of optical bodies having the widths of the dark portions and the rolls of 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm is 200% or more. It is advantageous that such an antiglare film also has an opacity of 15% or less.

Moreover, according to this invention, the image display apparatus using this anti-glare film is also provided, This image display apparatus is equipped with said any anti-glare film and image display means, The anti-glare film is arrange | positioned at the visual recognition side of an image display means. will be.

According to the present invention, a lithography step of forming irregularities on the photoresist film formed on the substrate by photolithography, and electroforming a metal on the uneven surface of the obtained photoresist film to transfer the uneven shape to the metal. The electroforming die manufacturing process which peels the metal plate in which the uneven shape was transferred from the photoresist film, and manufactures a metal mold | die, and transfers the uneven shape of the surface to the surface of a film using the metal plate in which the uneven shape was transferred in this way as a metal mold | die. As a method for producing an antiglare film having irregularities on the surface including an uneven film manufacturing step, the lithography step is provided by exposing and subsequently developing a photoresist film through a photomask having two or more kinds of patterns having different sizes.

In this method, it is advantageous that the photomask is formed such that the ratio of the diameter of the largest pattern to the diameter of the smallest pattern is 1.1 to 2 times. In addition, it is advantageous that the photomask has a pattern formed such that the ratio of the total area occupied by two or more kinds of patterns having different sizes is in the range of 0.7 to 1.3.

The exposure through the photomask is preferably performed by proximity exposure in which the photomask is disposed at intervals on the surface of the photoresist film. The exposure is performed under the condition that the distance between the photomask and the surface of the photoresist film is L (µm), the average diameter of the pattern of the photomask is D (µm), and the value of L / D ² is 1.3 or more and 2.8 or less. It is advantageous.

The photomask can be configured by arranging a plurality of unit cells having a predetermined area so as to maintain translational symmetry. In addition, when using the metal plate to which the uneven | corrugated shape was transferred as a metal mold | die, and transfers the uneven | corrugated shape to the surface of a film, you may wind up this metal plate on the surface of a roll so that the uneven surface may become an outer side, and an uneven film manufacturing process may be performed.

The anti-glare film of this invention controls the surface unevenness suitably, and when it is used for image display apparatuses, such as a liquid crystal display device, especially an image display apparatus with high precision, generation | occurrence | production of the phenomenon which hinders visibility, such as a glitter, is effective. Since it is possible to prevent this, it is possible to provide an image having excellent anti-glare effect and high visibility. In particular, such an effect becomes more remarkable by controlling also the optical characteristic of a film.

Moreover, according to this invention, the anti-glare film excellent in the optical characteristic can be manufactured productively and reproducibly.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows the outline of the surface shape of an anti-glare film.
FIG. 2 is a three-dimensional contour diagram showing the height of each point with respect to the surface of the portion having the antiglare film. FIG.
FIG. 3 is a two-dimensional contour diagram each showing a region (convex) higher than the average height in white and a region lower than the average height in black with respect to the surface of the portion having the antiglare film.
Fig. 4 is an example of a bar graph showing the frequency of the appearance of individual convexities or concave observed on the surface of the antiglare film, with the horizontal axis representing the area (unit is µm ² ) and the vertical axis representing the convexity or concave of the area. Frequency (unit is number).
FIG. 5 is an example of a bar graph showing the vertical axis as the area × frequency (unit: μm ² ) from the data of FIG. 4.
FIG. 6 is a diagram showing a method for obtaining a half width of a peak in a bar graph of a convex or concave apparent area, and is a bar graph showing an enlarged section in which the horizontal axis of FIG. 5 is 0 to 200 μm ² .
FIG. 7: shows the example of the manufacturing method of the anti-glare film concerning this invention for every process in a longitudinal cross-sectional schematic diagram.
It is a cross-sectional schematic diagram which expands and shows a part of FIG. 7 (B).
It is a perspective view for demonstrating the relationship between a specular reflectance and the reflectance by the angle (theta) inclined to the film side in the specular reflection direction.
FIG. 10 shows that the specular reflectance for incident light is R (0). When the reflectance at an angle θ inclined to the film side in the specular reflection direction is R (θ), R (θ) maximizes R (0). , it is a typical graph showing the form of monotonous decrease with increasing θ.
FIG. 11 is a perspective view for explaining the specular reflection angle and the reflectance in the direction twisted by 20 °.
12 is an enlarged view in which height information is converted to gray scales and displayed for a range of about 480 μm × about 640 μm in length of the antiglare film obtained in Example 1, and the right side shows a scale indicating height to be.
FIG. 13 is a bar graph showing the frequency with respect to the area of the occurrence of individual convexities or concave observed on the surface of the antiglare film obtained in Example 1. FIG.
FIG. 14 is a bar graph showing the vertical axis as area × frequency (unit is μm ² ) from the data of FIG. 13.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail, referring an accompanying drawing suitably. 1 is a perspective view which shows the outline of the surface of an anti-glare film. FIG. 2 is a three-dimensional contour diagram showing the height of each point with respect to the surface of the portion having the antiglare film. FIG. FIG. 3 is a two-dimensional contour diagram showing regions (convex) higher than the average height in white and regions (concave) lower than the average height in black, respectively, on the surface of the portion where the antiglare film is present. 4 is an example of a bar graph showing the frequency of the occurrence of individual convexities or concave observed on the surface of the antiglare film. 5 is an example of a bar graph showing the vertical axis as the area × frequency from the data of FIG. 4. FIG. 6 is a diagram showing a method for obtaining a half width of a peak in a bar graph of a convex or concave apparent area, wherein the abscissa in FIG. 5 is enlarged between 0 and 200 μm 2. FIG. 7: shows the example of the manufacturing method of the anti-glare film which concerns on this invention for every process in a longitudinal cross-sectional schematic diagram. It is a cross-sectional schematic diagram which expands and shows a part of FIG. 7 (B). It is a perspective view for demonstrating the relationship between a specular reflectance and the reflectance by the angle (theta) inclined to the film side in the specular reflection direction. FIG. 10 shows that R (O) is a specular reflectance for incident light, and R (θ) is maximized at R (0) when the reflectance at an angle θ inclined to the film side in the specular reflection direction is R (θ). , it is a typical graph showing the monotonous decrease with increasing θ. FIG. 11 is a perspective view for explaining the specular reflection angle and the reflectance in the direction twisted by 20 °. FIG. 12 is an enlarged view in which height information is converted to gray scales in a range of about 480 μm × about 640 μm in length of the antiglare film obtained in Example 1 to be described later, and the right horizontal line is a gray scale indicating height. FIG. 13 is a bar graph showing the frequency of the occurrence of individual convexities or concave observed on the surface of the antiglare film obtained in Example 1 in the same manner. 14 is a bar graph showing the vertical axis in terms of area x frequency from the data in FIG. 13.

With reference to FIG. 1, the anti-glare film of this invention is demonstrated. This anti-glare film 20 is formed with fine unevennesses (3) and (4) on its surface, and this itself is not different from the conventionally known anti-glare film. In FIG. 1, the surface (called main plane) of the average height of a film is shown by code | symbol (1), the projection surface is shown by code | symbol (2), respectively, and the rectangular coordinates in a film plane are shown by (x, y). In addition, the part (convex) 3 higher than average height is shown by the solid line, and the part (concave) 4 lower than average height is shown by the broken line, respectively.

In the present invention, the area higher than the average height of the unevenness is concave, the area lower than the average height of the unevenness is concave, the area of each convexity or the area of the concave is determined, and the frequency of this convexity or concave is determined for each predetermined area. Furthermore, when the frequency of the apparent area is calculated for each of the predetermined areas based on the area × frequency, and the frequency of the apparent area of the convex or concave obtained is represented by a bar graph, the peak value appears at a position of 300 μm ² or less. The half width of the peak is set to 60 µm ² or less.

In this bar graph, the larger the area value at which the peak value appears, the rougher the irregularities. The convex or concave having an area of 300 μm ² corresponds to a circle having a radius of about 10 μm, and in the case where a large number of such large convex or concave exists, that is, the peak value in the bar graph described above is greater than 300 μm ^2. If it appears, the sparkle becomes large and the visibility is impaired. It is further preferable that the peak value when the frequency of the apparent area of the convex or concave is represented by a bar graph is displayed at a position of 200 µm ² or less, and 150 µm ² or less, particularly 100 µm ² or less. In addition, the half value width of the peak which shows when the frequency of the convex or concave apparent area is shown by the bar graph corresponds to the distribution of the convex or concave apparent area per unit area.

As an anti-glare film obtained by disperse | distributing a conventional anti-glare film, especially a filler, the unevenness | corrugation of the part in which the filler was disperse | distributed well, and the dispersion state of a filler is bad, and the unevenness | corrugation of the aggregated part can be seen. In this state, simply counting only the number of unevennesses generally causes a large number of small unevennesses in the area where the filler is dispersed well, while extremely small number of unevennesses due to the aggregation of the fillers. By the way, when observing with an optical microscope, a stylus film thickness gauge, etc., the big unevenness | corrugation of the area by which the filler aggregated is remarkably observed. Regarding optical characteristics such as glitter, it is considered that the contribution of large irregularities of such an area is large, and an evaluation method considering the area of irregularities is necessary. Therefore, in this invention, the surface structure of an anti-glare film is prescribed | regulated by the distribution of the apparent area of convex or concave in consideration of the uneven | corrugated area.

About the anti-glare film of this invention, the method of obtaining the distribution of the apparent area of the convex or concave in the surface, and what it means is demonstrated below. First, in the arbitrary area | region of a film surface, the height of each point which comprises this film surface is measured, and the average value of the height in the whole measurement area is calculated | required. The convex area is defined as a convex region where the height is higher than the average value.

An example of the height distribution of the unevenness | corrugation of an anti-glare film is shown to FIG. 2 and FIG. FIG. 2 is a three-dimensional contour diagram showing the height of each point on the antiglare film surface for any horizontal resolution. On the other hand, in Fig. 3, the heights of the points obtained in the same manner as in Fig. 2 are averaged, and the collection of points higher than the average value, that is, the convex area referred to in the present invention is white, and the collection of points lower than the average value It is the two-dimensional contour diagram which showed the recessed area | region shown in invention in black, respectively. For example, each area is calculated | required following the convex area shown by white in FIG. Here, since the convex and the concave are considered to appear almost symmetrical in the height direction, respectively, the respective areas can be obtained in this way with respect to either the convex or the concave. It is more preferable that both the convex region and the concave region satisfy the requirements defined in the present invention. In addition, an area is calculated | required as a projection area rather than the surface area which convex or concave makes. In addition, in FIG.2 and FIG.3, only the some unevenness | corrugation is shown in order to make it easy to understand, In practice, the height of a surface is calculated | required in the area | region containing many unevenness | corrugation, and the average value of the height in front of the area | region is calculated | required of many convex or concave Find the area.

Fig. 4 is an example of a graph (bar graph) of the number distribution showing the number of individual convexities or concaves obtained in this manner for each predetermined area. Moreover, the product of the area | region and frequency of an area is taken from the frequency value for each predetermined area obtained in order to calculate an apparent area, and let it be the frequency of an apparent area. FIG. 5 is an example of a graph (bar graph) of the number distribution showing the frequency of the apparent area obtained from the graph of FIG. 4 in this manner for each predetermined area.

As shown in Fig. 4, as a bar graph showing the number (frequency) of convexity or concave with respect to the area, there are many convexities or concaves having a small area, and small convexities or concave with a large area are seen, but the optical properties have an area. The contribution by large convex or concave is large. Therefore, in the present invention, the frequency is multiplied by the area to find the frequency of the apparent area, and the distribution of the apparent area is obtained from the bar graph depicting it. In this specification, the full width at half maximum (also called full width at half maximum) in the bar graph of the apparent area thus obtained will be referred to as distribution of the apparent area. The method for obtaining the distribution of such apparent areas is described in more detail below.

The height of the film surface in which the unevenness | corrugation was formed can be calculated | required from the three-dimensional shape of the surface roughness measured using a non-contact three-dimensional surface shape and a roughness measuring instrument, an atomic force microscope (AFM), a laser confocal microscope, etc. The horizontal resolution required for the measuring device is at least 5 µm or less, preferably 2 µm or less, and the vertical resolution is 0.1 µm or less, preferably 0.01 µm or less. As a non-contact three-dimensional surface shape and roughness measuring instrument suitable for this measurement, the "New View 5000" series etc. which are available from Zygo Co., Ltd. in Japan as a product of an American company (Zygo Corporation) are mentioned. The larger the measurement area is, the more preferably at least 100 μm × 100 μm, preferably 400 μm × 400 μm or more.

Specifically, by using the above-described measuring device or the like, as shown in FIG. 2, data of heights corresponding to the respective x and y coordinates of the lattice determined by the horizontal resolution of the measuring machine can be obtained. The average value of all height data is taken, and the area | region higher than an average value is considered convex, and the area | region lower than an average value is regarded as concave. The irregularities thus obtained are converted into two digitized images, and the area of the convex or concave is calculated using image processing software. The image processing software is not particularly limited as long as the number of the convex or concave pixels can be counted. However, in the examples shown in FIGS. 4 and 5 and the embodiments described later, NIH image is used as the image processing software. The number of pixels of each part corresponding to the convex or concave of one image was counted to obtain an area. NIH image is image processing software developed by the National Institute of Health (NIH) in the United States, and named NIH image using the name of the development agency.

Next, the area is divided into equal parts so that the area between the maximum area and the minimum area obtained by the image processing can be divided into 10 to 100 equal parts, and the number of the convex or concave corresponding to the area between the divided adjacent areas is calculated. Find the frequency. If the division of the area is too thin, the frequency becomes too discrete to obtain a distribution. On the contrary, if the division of the area is too large, it is not preferable because the frequency is roughly visible. In the example shown to FIG. 4 and FIG. 5, and the Example mentioned later, area was divided by 10 micrometer <^2> space | interval. That is, in FIG.4 and FIG.5, the area of a horizontal axis is shown by 10 micrometer <^2> space | interval, and writing "O" in the first division part means O micrometer ² or less, and the next division part is from O micrometer ² The area up to 10 micrometer <^2> , and the division part of the part which is "50" after that means the area from 40 micrometer <^2> to 50 micrometer <^2> . The same applies to the following Figs. 6, 10 and 11 showing the bar graph.

In addition, in order to obtain the distribution of the apparent area, the product of the average value of each adjacent area and the number (frequency) of the convex or concave belonging to the section is taken as the frequency of the apparent area. For example, when the area is divided by 10 μm ² intervals, the frequency of the apparent area is 25 μm ² × assuming that the number of convexities or concaves between 5 μm ² and 30 μm ² (median value of 25 μm ² ) is five. 5 pieces = 125 micrometer <^2> . A bar graph of the apparent area is created by showing the frequency of the obtained apparent area with respect to the area value. The half width of the peak of this bar graph was defined as the distribution of the apparent area of unevenness. Peak value in the histogram of the "area × frequency" of the area column of "area × frequency" maximum value of which, that is, the example of Figure 5 say 20 ㎛ ² × 30 ㎛ ² in the histogram obtained as described above It is a value appearing in the area division part between.

Here, a method for obtaining the half width of the peak in the bar graph will be described based on FIG. 6. FIG. 6 enlarges the bar graph of FIG. 5 with respect to the horizontal axis of 0-200 micrometer <^2> . In addition, the point which shows the largest value of a vertical axis (area X frequency) in the whole measurement range is called the point P which shows a peak value. A straight line parallel to the abscissa through the point C that bisects the peak line segment PB, assuming that the point A intersects the straight line A at the point P, and intersects the straight line of the area x frequency = 0 of the abscissa. Tooth line) and the area spacing between the minimum and maximum values at which it intersects the bar graph is called half width WH. 6, when the bar graph descending at the point P representing the peak value rises again before reaching the half value of the peak value, or when the bar graph becomes less than the half value of the peak value and rises again and exceeds the half value of the peak value. The bar graph does not exceed the half value of the peak value again, and finally, the points U and V exceeding the half value are determined, and the half value width WH is determined with the width between the UVs. In determining the full width at half maximum, WH, the minimum at which the half-line intersects the bar graph is the minimum of the facet segment represented by the bar column, and the maximum at the half-line intersects the bar graph is the maximum value of the area segment represented by the bar column. do. That is, in the example shown in FIG. 6, since the half-line crosses last with the bar column which shows the area between 10 micrometers ² and 20 micrometers ² on the small area, the value of the point U is set to 10 micrometers ² In addition, since the half line intersects the bar column which shows the area between 140 micrometers ² and 150 micrometers ² on the large area, the value of the point V is set to 150 micrometers ² , Therefore, the half width WH of this example is 140 M ² (= 150-10).

In the bar graph for the area of "area x frequency" obtained as described above, if the half width of the peak is 0, the convex or concave area is concentrated at one point. On the other hand, when this half value width becomes large, it means that the distribution of the apparent area of each unevenness | corrugation is large. The smaller this half-value width, the narrower the distribution of the apparent area of each unevenness.

When the distribution of the apparent area is wide, it was found that the cause is not clear, but the sparkle increases, corresponding to the convex or concave of the large apparent and the convex or concave of the small apparent. In addition, when the apparent area distribution is narrow, it is evident that the shimmer decreases when combined with the high-precision panel in response to the relatively identical areas of the convex or concave areas. When the half width of the peak in the distribution of the apparent area, that is, the frequency of the above-mentioned apparent area exceeds 100 µm ² , the sparkling becomes large and the visibility is significantly reduced. On the other hand, if the distribution of the apparent area (half width of the peak) is 60 µm ² or less, the sparkling is hardly observed and good visibility can be obtained. So, in particular in order to increase the visibility of the highly precise display device, it is important to the distribution (full width at half maximum of the peak) of the apparent surface area to 100 ㎛ ² or less, and preferably such that the full width at half maximum is the 6O ㎛ ² below. The half value width of the peak in the bar graph which shows the frequency of an apparent area becomes like this. More preferably, it is 50 micrometer <^2> or less. However, when the unevenness is regularly parallel and the half width is 0, the interference line is conspicuous, and when the half width is 10 µm ² or less, this tendency starts to appear. Therefore, it is preferable that the apparent area of the convex or concave has a certain degree of distribution, and it is preferable that the above half-value width is larger than 10 µm ² .

Although the film which has the surface shape specified by this invention can be manufactured by arbitrary methods, For example, the method of pressing and shape | molding a thermoplastic transparent resin film by heating to the embossing mold which has an appropriate surface shape, and the said embossing mold To a transparent base material coated with ultraviolet curable resin on the ultraviolet curable resin coated surface, and can be produced by a method of irradiating and curing ultraviolet rays in that state.

As a manufacturing method of an embossing mold, the method which combined the formation of the unevenness | corrugation by photolithography and the electroforming (electroplating) of a metal to it is mentioned as a preferable thing, for example. Specifically, a photoresist film is formed on the substrate, and gray scale exposure is performed thereon, followed by development, thereby forming irregularities on the photoresist film, and electroforming a metal on the photoresist film on which the irregularities are formed. By peeling a metal from a photoresist film, the metal plate in which the uneven | corrugated shape was transcribe | transferred, ie, the embossing mold is manufactured. Using this embossing mold, a method of pushing a thermoplastic transparent resin film into this embossing mold in a heated state or a transparent base material coated with an ultraviolet curable resin is brought into close contact with the embossing mold on the ultraviolet curable resin coating surface to irradiate ultraviolet rays in that state. To obtain an antiglare film in which a predetermined surface shape is shaped by a method of curing an ultraviolet curable resin.

Thus, the example of the method of manufacturing an embossing mold by a combination of photolithography and electroforming, and using it to manufacture an anti-glare film is demonstrated by FIG. First, as shown in Fig. 7A, a photoresist film 12 is formed on the surface of the substrate 11 for forming a photoresist film. The base material 11 used here may be one whose surface is flat and which a photoresist film adheres suitably, For example, inorganic transparent base materials, such as glass, quartz, and alumina, metal base materials, such as copper and stainless copper, are mentioned, for example. Can be. In addition, the photoresist applied on the base material 11 may have photosensitivity, and may have an appropriate resolution, and a positive photoresist or an exposed portion which is exposed after the development of the exposed portion becomes soluble in the developing solution and removed after development is hardened. All of the negative photoresist which becomes insoluble in and removes an unexposed part by development can be used. For example, photosensitive compounds such as novolak resins, acrylic resins, copolymers of styrene and acrylic acid, alkali-soluble resins such as polyvinylphenol and poly (o-methylvinylphenol), and quinonediazide group-containing compounds may be used in the organic solvent. And a negative photoresist composition obtained by dissolving a positive photoresist composition obtained by dissolving, a photosensitive resin containing an alkali-soluble resin, a photoacid generator, a crosslinking agent, and the like in an organic solvent. However, in order to cause diffraction of light to an edge part by proximity exposure in a subsequent exposure process, and to form a rounded recessed part by subsequent development, a positive photoresist is preferable. An example shown below with reference to FIG. 7 is a case where a positive photoresist is used.

The thickness of the photoresist film 12 formed on the base material 11 can be appropriately adjusted according to the depth, shape, etc. of the unevenness to be formed on the surface of the antiglare film, and is equal to or slightly less than the desired depth of the unevenness. It is preferable to form thickly. As a specific film thickness range, it is preferable that it is more than the depth of the unevenness | corrugation made into the objective, and the depth of the unevenness | corrugation made into the objective +5 micrometer or less.

In order to form the photoresist film 12 on the base material 11, a well-known suitable coating method, such as a spin coating method, a dip coating method, a roll coating method, can be used, for example. After the film is formed, prebaking is usually performed to remove the solvent contained in the photoresist. Prebaking is carried out for a time of about 0.5 to 10 minutes at a temperature of about 60 to 120 ℃ using, for example, a hot plate or an oven. The temperature and time of prebaking can be suitably adjusted according to the kind of photoresist, the sensitivity required for a photoresist, etc.

In this way, the photoresist film 12 formed on the substrate 11 is subsequently subjected to gradation exposure as shown in Fig. 7B. In FIG. 7B, an example in which gradation exposure is performed through a two-tone photomask 14 is disclosed. A two-tone photomask is a portion that transmits light from an exposure light source on a substrate made of glass, quartz, or the like that is transparent to an exposure light source, and is a portion that shields light from the exposure light source and a transmission portion having a transmittance of 100% or less. The light-shielding part whose transmittance | permeability is 0% or near is formed. Specifically, the metal mask in which metals, such as chromium, etc. were formed as a light shielding part on the transparent substrate with respect to an exposure light source, the emulsion mask etc. in which the light shielding part was formed by exposing an oil etc. are mentioned.

Such two-tone photomasks 14 are arranged at intervals slightly on the surface of the photoresist film 12 as shown in Fig. 7B, and exposing the substrate. Proximity exposure means exposing the photomask 14 to the photoresist film 12 so as to be spaced apart from each other without being in close contact. By performing proximity exposure using such a two-tone photomask 14, light diffraction occurs at the edge portion of the mask pattern of the photomask 14, the image of the photomask 14 is blurred, and the light beam 15 passing through the transmission portion. ) Shows magnification over the rear surface of the light shielding portion, and continuous light quantity distribution occurs. Since the photoresist film 12 is exposed to light depending on the distribution of the amount of light exposed to the proximity light, the remaining photoresist film is changed in accordance with the amount of irradiation light by the subsequent development, and the mask pattern is formed on the surface of the photoresist film 12 after development. Unevenness is formed according to the exposure amount, the distance between the photomask and the photoresist film (called an exposure gap or the "proxy meti gap") and the like. At this time, only one type of opening diameter of the photomask may be used, but it is also effective to form a photomask by combining a plurality of types of opening diameters, for example, two or three types.

Although FIG. 7B shows an example of performing grayscale exposure by exposing the proximity using a two-tone photomask 14, an exposure light source according to a method and a place of performing grayscale exposure through a multi-tone photomask. The same effect can also be obtained by a method of performing gradation exposure through a spatial light modulation element capable of changing the light intensity of the light.

A multi-gradation photomask is a photomask in which the transmittance varies in multiple stages or continuously depending on the place, unlike the above-described two-gradation photomasks. As such a multi-gradation photomask, for example, a high-resolution photomask drawing apparatus such as an electron beam drawing apparatus is used, and a light shielding portion and a transmission portion having a size sufficiently smaller than the wavelength of the exposure light are provided, and the light shielding portion and the transmission portion and The gray scale is expressed by the ratio of the area, and the mask blanks are formed by dispersing a material whose photosensitivity is changed by high energy, such as an electron beam or a laser beam, in a transparent medium. By continuously changing the transmittance, having a photosensitive property such as an emulsion, and forming a material whose optical density varies according to the amount of light to be irradiated on the substrate, and changing the amount of light to expose the material, and changing the optical density according to the place. The thing etc. which were changed can be used.

On the other hand, a spatial light modulation device capable of varying the light intensity of an exposure light source according to a place is one capable of spatially changing the intensity of light transmitted through the device or light reflected by the device, for example, a liquid crystal device or a digital device. And an optical modulation device in which a plurality of pixels including a micro mirror device (DMD) and the like are arranged. In the case where the liquid crystal element is used as the spatial light modulation element, the transmittance can be set for each pixel of the liquid crystal element constituting the plurality of pixels, thereby allowing the liquid crystal element to pass light having a spatially uniform intensity distribution from the exposure light source. The intensity distribution of the exposure according to the transmittance of the pixel of the element can be obtained, and the spatial intensity distribution of the exposure light irradiated to the photoresist film is produced. In addition, when DMD is used as the spatial light modulation element, the angle of inclination of the micromirror changes the reflection of light in the direction of the photoresist film and the reflection in the direction other than the photoresist film, but in the direction of the photoresist film. By changing the reflecting time for each pixel, the actual reflectance per unit time can be changed for each pixel. That is, by reflecting the light having a spatially uniform intensity distribution from the exposure light source into the DMD, the intensity distribution of the exposure light according to the time the micromirror is inclined can be obtained, and the spatial intensity distribution of the exposure light irradiated onto the photoresist film is Will occur.

The light source used for the exposure may be a photoresist film 12, and a suitable light source is used according to the type of photoresist. For example, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, or the like may be used as a light source, and may use near-ultraviolet rays such as g-rays, h-rays, and i-rays, or a laser beam having a transmission wavelength at a wavelength close to those of mercury. . During exposure, an optical member such as a lens system, a mechanical member such as a mask alignment, or the like may be interposed between the exposure light source and the photoresist film within a range that does not impair the effect of the present invention.

The photoresist film 12 subjected to gradation exposure in this manner is then subjected to a developing process, and as shown in FIG. 7C, a photoresist film 13 having irregularities is obtained. For example, the developing treatment is performed by contacting the developed photoresist film 12 formed on the substrate 11 with a developer according to the kind thereof, and in the case of a positive photoresist, by removing the exposed portion on the photoresist film 12. To form. The developer may be appropriately selected and used according to the type of photoresist from conventionally known ones. After development, rinsing with water and post-baking are usually carried out. By post-baking, the intensity | strength of a residual photoresist film can be improved, and adhesiveness with the board | substrate 11 can be improved. This postbaking also acts to deactivate the photosensitivity of the unexposed residual film portion. Post-baking is performed for about 0.5 to 30 minutes at the temperature of about 100-200 degreeC using oven, a hotplate, etc., for example.

In this way, the photoresist film 13 in which the unevenness | corrugation was formed was subsequently electroformed with the metal 17, and the unevenness | corrugation of the surface of the photoresist film 13 was electroformed as shown in FIG.7 (D). ) Is transferred to. The metal used for electroforming may be what is conventionally used in the field of electroplating, For example, nickel, nickel-phosphorus alloy, iron-nickel alloy, chromium, chromium alloy, etc. are mentioned. The thickness of the metal 17 formed on the photoresist film 13 by electroforming is not particularly limited, but is preferably about 0.05 to 3 mm in view of durability. In the case of performing electroforming directly on the photoresist film 13, it is necessary to conduct the surface of the photoresist film 13 before electroforming, and this conducting treatment is performed by, for example, forming a metal film having a thickness of 1 m or less. It may be performed by a method of forming by vapor deposition, sputtering, or the like, a method by electroless plating, or the like. In the case where it is not desired to perform electroforming directly on the photoresist film 13, for example, the concave shape on the photoresist film 13 is not transferred to the metal 17 to form a convex shape, but the photoresist film 13 is formed. In the case where the same concave shape of the phase is to be transferred to the metal 17 to be concave, for example, the concave-convex shape formed on the photoresist film 13 is transferred to the resin, and then the concave-convex surface of the resin is described above. The electroconductive process can be performed by the method as mentioned above, and the method of electroforming can be used there.

The metal plate 17 to which the unevenness of the photoresist film 13 having unevenness is transferred is then peeled from the photoresist film 13 or the unevenness of the photoresist film 13 is transferred to the resin thereafter. In the case of electroforming, the metal sheet is peeled off from the resin to form a metal plate having an uneven surface formed on the surface, that is, an embossed mold 18 as shown in Fig. 7E.

Using the metal mold | die 18 which is the embossing mold obtained in this way, the unevenness | corrugation formed in the surface is transferred onto a film, and an anti-glare film is obtained. In the example shown to FIG.7 (F) and (G), the ultraviolet curable resin 22 is apply | coated on the transparent base film 21, and it adheres to the embossing mold 18 from the ultraviolet curable resin 22 side, The anti-glare film 20 in which the ultraviolet-ray was irradiated from the transparent base film 21 side, hardened | cured ultraviolet curable resin 22, and the layer of the ultraviolet curable resin 22 which has unevenness | corrugation on the transparent base film 21 was formed. Is supposed to get As described above, not only this example but also the antiglare film having irregularities formed on the surface can be obtained by the method of pressing and shaping the thermoplastic transparent resin film by pressing the embossed mold 18 in the form of heating.

When the ultraviolet curable resin 22 is apply | coated on the transparent base film 21, and an unevenness | corrugation is transferred to the ultraviolet curable resin 22 side like the example shown to FIG.7 (F) and (G), an ultraviolet-ray As curable resin, any commercially available thing can be used. For example, polyfunctional acrylates, such as a trimethylol propane triacrylate and pentaerythritol tetraacrylate, are used individually or in mixture of 2 or more types, and it is "Irugacure 907" and "Iruga" What mix | blended photoinitiators, such as Cure 184 "(above, Chiba Specialty Chemicals Co., Ltd.)," Lucirine TPO "(made by BASF Corporation), can be made into ultraviolet curable resin.

On the other hand, when a thermoplastic transparent resin film is used and the method of shaping the unevenness of the mold 18 therein is used, any of the thermoplastic transparent resin films can be used as long as it is substantially transparent. For example, polymethyl methacryl A solvent cast film, an extruded film, etc. of thermoplastic resins, such as an amorphous cyclic polyolefin which uses as a monomer the rate, polycarbonate, polyethylene terephthalate, a triacetyl cellulose, and a norbornene-type compound, can be used. This transparent resin film can also be the transparent base film 21 at the time of using the ultraviolet curable resin demonstrated above.

In the present invention, a photomask 14 having two or more types of patterns having different sizes is used in the lithography step, particularly the exposure step shown in Fig. 7B. The pattern here is at least an individual transmission part (opening) or a light shielding part having a sufficiently large size compared to the wavelength of the exposure light. That is, using a high-resolution photomask drawing device such as an electron beam drawing device, such as an electron beam drawing device, a transmissive part and a light shielding part having a size sufficiently smaller than the wavelength of the exposure light are provided to provide an area ratio of the transmissive part and the light shielding part. It does not refer to the transmissive portion or the light shielding portion sufficiently smaller than the wavelength of the exposure light in the case of expressing the gradation to make the gradation mask. In addition, in the present invention, the diameter of the circle providing the same area as the area of the pattern is referred to as the size of the pattern.

When using the thing of the pattern of the same magnitude | size as a two-tone photomask, the shape of the unevenness | corrugation formed on the photoresist film by photolithography becomes what has almost the same size. As described above, in consideration of the size of the pixel in an image display device such as a liquid crystal display device or a plasma display panel, when the pattern formed on the photoresist film is almost the same size, the unevenness is applied to the metal plate by electroforming. Since the unevenness on the film is about the same size even after the transfer and the unevenness of the metal plate are transferred to the film, the reflected light based on the unevenness of the surface tends to be colored in rainbow colors by interference or diffraction of the reflected light.

In the present invention, since photolithography is performed using photomasks having patterns of different sizes, the shape formed on the photoresist film is various in size, and the interference and diffraction of the reflected light as described above are difficult to occur. The phenomenon such as coloring of reflected light due to unevenness or increase in reflectance of light of a specific wavelength at a specific angle is reduced.

In this photomask, if the difference in the size of the pattern is too small, the unevenness formed on the photoresist film becomes almost the same size, and the effect intended in the present invention is hardly exhibited sufficiently. On the other hand, if the difference in the size of the pattern is too large, the photo There exists a tendency for the density of the part with a pattern and a part without a pattern to become too large on the mask, and to make it hard to achieve uniform anti-glare property. Therefore, the size of the pattern formed on the photomask is preferably such that the ratio of the maximum size (diameter) to the minimum size (diameter) is 1.1 times or more and 2 times or less. The ratio of the magnitude | size of this pattern becomes like this. Preferably it is 1.2 times or more, 1.5 times or less, More preferably, it is 1.3 times or less. It is preferable to make each pattern into the range of 1-50 micrometers in diameter according to the display apparatus to which the target anti-glare film is applied, and it is more preferable to set it as 5 micrometers or more and 30 micrometers or less.

It is preferable that the total area on the photomasks of the patterns of different sizes does not vary too much between the respective patterns. That is, for example, when the pattern X of a certain size and the pattern Y of a different size are mixed, it is preferable that the ratio of the total area of the pattern X and the total area of the pattern Y is in the range of about 0.7 to 1.3. When three or more types of patterns having different sizes are mixed, such a relationship may be satisfied between any two types therebetween, but it is more preferable to satisfy these relationships among respective patterns having different sizes.

As shown in Fig. 7B, it is preferable to arrange the photomask 14 of two gradations on the surface of the photoresist film 12 at intervals to perform proximity exposure. As described above, the proximity exposure means that the photomask 14 is placed close to the photoresist film 12, but is not exposed to the photomask 14 so as to be disposed at a slight interval. By performing proximity exposure using such a two-tone photomask 14, as shown schematically in FIG. 7B, light diffraction occurs at the edge portion of the mask pattern of the photomask 14, and the photomask 14 ), The light beam 15 passing through the transmission part shows magnification over the back surface of the light shielding part, and continuous light quantity distribution occurs. Since the photoresist film 12 is exposed to light depending on the distribution of the amount of light exposed to the proximity light, the remaining thickness of the photoresist film changes depending on the amount of irradiation light by the subsequent development, and thus the surface of the photoresist film 12 after development. Unevenness is formed in the mask pattern, the exposure amount, and the gap between the photomask and the photoresist film (called an "exposure gap" or "proxyty gap").

In performing exposure using a two-tone photomask as described above, when the distance between the photomask and the photoresist film is L (µm) and the average diameter of the pattern of the photomask is D (µm), L to / D ² value of the conditions that 1.3 or 2.8 or less, that is, it is preferable to perform the exposure under the same conditions as those that satisfy the equation (1).

The relationship between the space | interval L of a photomask and a photoresist film, and the average diameter D of the pattern of a photomask is demonstrated based on FIG. 8 which expanded part of FIG. 7 (B). As shown in this figure, the distance between the photomask 14 and the surface of the photoresist film 12 is L. FIG. In the present invention, since photomasks having two or more kinds of patterns having different sizes are used, for example, the photomask 14 has three kinds of patterns, and the diameter of each pattern is D ₁ , D _2. And D ₃ . The average diameter D of a pattern is made into the weighted average which added the magnitude | size and each number of each of these different types of patterns. In the case of having three types of patterns having diameters D ₁ , D _2, and D ₃ as shown in FIG. 8, the number of each pattern in the entire photomask or the unit area is N ₁ , N ₂ , and N _3. The average diameter D is calculated by the following equation.

By the way, the magnification of the image of the light passing through the fine opening varies depending on the index (L / D ² .lambda) including the distance L between the opening and the photoresist film, the opening dimension D, and the wavelength of the light. When the distance between the film and the film is small, the shape of the opening is almost transferred onto the photoresist film. As the distance between the opening and the photoresist film is increased, the diffused light centered on the optical axis is radiated onto the photoresist film. do. Therefore, if the value of L / D ² is too small, the exposure image formed on the photoresist film reflects the opening pattern on the photomask, and the energy distribution also changes abruptly in correspondence to the opening shape. This tends to be formed, and there exists a tendency for the scattering function of the light of the anti-glare film obtained therefrom to fall. On the other hand, the greater the value of L / D ² too, is discarded light is diffused diffraction in the photomask, the pattern tends to be formed in the photoresist film surface is difficult. It was confirmed by experiment that if the value of L / D ² is in the range of 1.3 or more and 2.8 or less, an approximately good exposure image can be formed.

In addition, in the above description, according to FIG.7 (A)-(E), it develops by performing gradation exposure on the photoresist film 12, and makes into the original what formed the unevenness, and finally it is continuous on a film The antiglare film 20 to which the uneven shape is transferred is produced. Therefore, in order to make the photomask 14 for original plates, it is necessary to design a mask pattern, but this mask pattern is designed so that the shape prescribed | regulated by this invention may be obtained. Designing such a mask pattern over the entire surface of the photomask 14 is very cumbersome and because the data capacity of the mask pattern is large, the burden on the mask writer also increases, which in principle is possible but not necessarily practical. none. Therefore, it is advantageous to design a mask pattern constituting a unit cell including a predetermined area, and arrange a plurality of such unit cells so that translational symmetry is maintained, so as to form a photomask that covers the entire surface of the photoresist film 12. Do. By using such a method, the time for designing the mask pattern as the entire photomask 14 can be reduced, which is industrially advantageous. Here, the translational symmetry means that the unit cells are arranged side by side in a constant direction such as front and rear, left and right directions or inclined directions. As an example of the state in which the mask pattern was arrange | positioned so that translational symmetry may be maintained, the state in which the center coordinates of each unit cell were arrange | positioned in grid form, such as a square lattice, a rectangular lattice, a square lattice, a hexagonal lattice, is mentioned.

In the photomask having two or more kinds of patterns having different sizes, the kinds of patterns may be two or more kinds, and the upper limit of the kinds is not particularly limited. However, as the type of patterns increases, the data capacity for designing a mask pattern also increases. Therefore, it is preferable to select a kind of pattern suitably according to the target performance in the range of two types, three types, four types, and about 5 types practically.

In addition, as mentioned above, the metal plate in which the unevenness | corrugation was formed, ie, the embossing mold 18, was wound up on a roll, or the embossing roll which has an unevenness | corrugation on the surface by winding in such a state that the said embossing mold 18 was arranged on the roll surface of several sheets as needed. The method of manufacturing and continuously transferring an uneven | corrugated shape to a film surface using this embossing roll is also preferable. By using this method, the uneven shape can be continuously and efficiently transferred to a large-area film, and high productivity can be obtained.

As described above, unevenness is formed by photolithography which is exposed and developed through a photomask having two or more kinds of patterns having different sizes, and a metal is produced by electroforming thereon to form a mold. Fine irregularities are formed on the surface by the method of transferring the unevenness to the antireflection, and thus an antiglare film having good antiglare performance and excellent optical characteristics can be produced. At this time, antiglare performance and optical characteristics can be controlled by appropriately selecting conditions such as a pattern of the photomask, an exposure amount, an exposure gap, and the like.

In the present invention, since a mold having fine unevenness is manufactured by combining the formation of unevenness by photolithography and electroforming of metal thereon, a method of transferring unevenness to the surface of the film using the die is used. The anti-glare film which has an uneven distribution which affects anti-glare property is uniform, and shows high performance can be manufactured with favorable productivity. Specifically, for example, the reflectance (the specular reflectance) in the specular reflection direction with respect to the incident light incident at any angle of 5 to 30 ° in the normal direction of the antiglare film is set to R (0), and the specular film is formed on the specular film side in the specular reflection direction. When the reflectance with respect to the incident light at the inclined angle θ is R (θ), it is easily obtained that the reflection profile showing the θ dependency of R (θ) is monotonically reduced.

The concept of this reflection profile measurement is shown in FIG. That is, the specular reflection direction is in the plane 26 including the normal 25 and the incident light beam direction 30 when the light beam 30 is incident at an angle ψ with respect to the normal direction 25 of the antiglare film 20. Refers to the direction of light 32 reflecting at an angle ψ in a direction opposite to the incident light beam direction 30. ψ is the angle of incidence and the specular reflection angle, but the sign is strictly opposite. The reflectance in the specular reflection direction 32 with respect to the incident light from the incident light direction 30 becomes the specular reflectance R (0). And when the incidence angle ψ is arbitrarily set between 5 ° and 30 °, in the plane 26 including the film normal direction 25 and the incident light direction 30, the antiglare film (from the specular reflection direction 32) In the direction 34 in which only the angle θ is inclined toward the 20) side, the reflectance of the incident light is measured, and this is called R (θ). When the inclination angle θ is changed from 0 ° (ie, the specular reflection direction) to 90 ° -ψ (ie, the direction parallel to the film plane) to measure and show the reflectance R (θ) for each inclination angle θ, generally θ = 0 ° R (θ) at the time, that is, R (0) is the maximum. In the graph of the reflectance R (θ) with respect to the inclination angle θ. As shown schematically in FIG. 10, it is easily obtained by the method of the present invention to provide a profile in which the θ dependency of R (θ) is monotonically decreasing.

The glare of the antiglare film can be evaluated by placing an antiglare film on a high-precision liquid crystal panel, illuminating the liquid crystal panel and the antiglare film with light from a backlight, and visually inspecting the panel surface. The more precise the liquid crystal panel used for evaluating the glitter, the more likely it is to see the glitter. The precision of the panel is preferably 150 ppi (pixel per inch) or more, more preferably 170 ppi or more.

It is preferable that the anti-glare film of this invention is 0.001% or less in the reflectance in the direction twisted 20 degrees from a regular reflection angle. As shown in FIG. 11, the direction twisted by 20 degree from a specular reflection angle means the direction 9 in which the inclination-angle (theta) corresponds to 20 degrees in said FIG. 9, and twisted 20 degrees from the specular reflection direction (8). The direction (9) twisted 20 ° from the specular reflection angle appears conical about the specular reflection direction (8), but the reflectance from the specular reflection angle to the direction twisted 20 ° is determined by the normal (5) and the incident light beam direction (6). The reflectance in the direction twisted 20 degrees to the film side in the containing plane 7 is meant.

Moreover, it is preferable that this anti-glare film is 50% or less of 45 degree reflection sharpness measured using the optical body of 1.0 mm of a dark part and a roll. 45 degree reflection sharpness can be calculated | required by the measuring method of the image sharpness by the reflection method prescribed | regulated to JISK7105. The incident direction and the reflection direction of light to the test piece at the time of a measurement shall be 45 degrees according to this JIS specification. In JIS, four types are defined, in which the ratio of the width of the dark portion to the wrist is 1: 1 and the width is 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm as the optical body, but is defined in the present specification and claims. The 45 ° reflection clarity is a value obtained when an optical body having a width of 1.0 mm and a dark portion is used.

Moreover, it is preferable that the total value of the transmission clarity measured with the four types of optical bodies whose width | variety of a dark part and a roll is 0.125mm, 0.5mm, 1.0mm, and 2.0mm of this anti-glare film is 200% or more. The transmission sharpness can also be determined in accordance with the method for measuring image sharpness by the transmission method specified in JIS K 7105. The direction of incidence of light on the test piece is a vertical direction in accordance with the provisions of this JIS. In this case, the image sharpness by the transmission method is measured about each of the four types of optical bodies described above, and their total value is defined as the total value of the above-mentioned transmission sharpness.

Moreover, it is preferable that the opacity of the anti-glare film of this invention is 15% or less. Opacity can be calculated | required by the method prescribed | regulated to JISK7105. The opacity value is a value expressed by (diffusion transmittance / total light transmittance) × 100 (%). As the antiglare film of the present invention, the opacity value measured by this method is generally 20% or less, but it is preferable that the opacity value is 15% or less, and even more preferably 10% or less. If the opacity value is too high, when the anti-glare film is applied to a display device, particularly a liquid crystal display device, low contrast light that is emitted in a direction inclined from the normal, in particular, in a direction inclined at 60 ° or more due to the viewing angle characteristic of the liquid crystal display device Since scattering is observed in the front direction, the contrast is reduced when viewed from the front.

Since the anti-glare film of this invention comprised as mentioned above is excellent in an anti-glare effect and the glitter when combined with a high-definition display panel improves favorably, it becomes excellent in visibility when attached to an image display apparatus. When an image display apparatus is a liquid crystal display, this anti-glare film can be made into a polarizing film. That is, the polarizing film generally has a shape in which a protective film is laminated on at least one side of a polarizer including a polyvinyl alcohol-based resin film in which an iodine or a dichroic dye is adsorbed and oriented, but on one side of such a polarizing film, When the anti-glare film provided with the unevenness is bonded, it becomes an anti-glare polarizing film. In addition, an anti-glare polarizing film can also be obtained by using the optical film provided with the anti-glare irregularities as described above as a protective film and an anti-glare layer, and bonding the uneven surface to the one side of the polarizer so that the uneven surface becomes the outer side. . Moreover, in the polarizing film in which the protective film was laminated | stacked, it can also be set as the anti-glare polarizing film by providing the anti-glare unevenness | corrugation as mentioned above to the surface of this single-sided protective film.

The image display apparatus of this invention arrange | positions the anti-glare film which has a specific surface shape as above-mentioned in image display means. Here, the image display means includes a liquid crystal cell in which a liquid crystal is enclosed between upper and lower substrates, and a liquid crystal panel which displays an image by changing the alignment state of the liquid crystal by applying voltage is representative of other plasma display panels and organic light emitting (EL ) Or an organic light emitting diode (O-LED) display, a cathode ray tube (CRT) display, and the like. And an image display apparatus is comprised by arrange | positioning the said anti-glare film on the visual recognition side rather than an image display means. At this time, it is arrange | positioned so that the uneven surface of an anti-glare film may become an outer side (viewing side). The anti-glare film may be directly bonded to the surface of the image display means, and when the liquid crystal panel is used as the image display means, for example, as described above, it may be bonded to the surface of the liquid crystal panel through the polarizing film. Thus, the image display apparatus provided with the anti-glare film of this invention can scatter an incident light by the unevenness | corrugation of the surface which an anti-glare film has, and can blur a projection image, and will provide the outstanding visibility.

<Examples>

Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited by these Examples. In the examples,% indicating content to the amount used is based on weight unless otherwise specified. In addition, the evaluation and the measuring method of the anti-glare film in the following examples are as follows.

(Measurement of surface shape and calculation of the apparent area of convex or concave)

The surface shape was measured about the area | region of about 480 micrometers x 640 micrometers of an anti-glare film using the non-contact three-dimensional surface shape roughness measuring machine "New View 5010" (made by Zygo Corporation). The meter has a horizontal resolution of 1.18 μm and a vertical resolution of 0.1 nm. The average value of all obtained height data is taken, and the area higher than the average height (convex) and the area lower than the average height (concave) are converted into two numerical images by the image processing software "NIH image", and the individual convex or The area of concave was calculated | required. Dividing the individual area data obtained by 10 ㎛ ² and was determined the frequency (number) of each per 10 ㎛ ^2. Next, by multiplying the frequency of each one 10 ㎛ ² area, the average area was calculated the rate of surface area of the each 10 ㎛ ^2. The frequency of the obtained exterior area was shown with respect to the area value, and the graph (bar graph) of the distribution of the tap water of the exterior area was created. From this bar graph, the half width of the peak, that is, the distribution of the appearance area was determined.

(Measurement of Reflectance of Anti-glare Film)

In the inclined surface of the antiglare film, the light of the parallelized halogen lamp light source is condensed and irradiated so as to have a solid angle of 3.4 ° in a direction inclined at 30 ° to the film main normal, and in a plane including the film main normal and the irradiation direction. The angle change of the reflectance was measured. The 3292 03 optical power sensor and the 3292 optical power meter by Yokogawa Denki Co., Ltd. were used for the measurement of reflectance.

(Measurement of opacity)

It measured according to JIS K 7105. The sample was used for the measurement after bonding to the glass substrate so that it might become an uneven surface, using the optically transparent adhesive agent in order to prevent curvature.

(Measurement of Reflective Sharpness and Transparency Sharpness)

It measured according to JIS R 7105. When measuring the transmission clarity, in order to prevent the bending of the sample, it was bonded to a glass substrate using an optically transparent adhesive and then provided for the measurement. When measuring the reflection clarity, the same glass-bonded sample was used as the measurement of the transmission clarity, but in order to prevent reflection on the glass surface, a black polymethyl methacrylate plate having a thickness of 2 mm was added to the glass surface of the glass plate with the antiglare film. It adhere | attached and adhere | attached, and in this state, light was incident on the sample (anti-glare film) side, and it measured.

&Lt; Example 1 >

In an area of 10 mm x 10 mm, the diameter is 8 µm, 9 µm And a unit cell in which three circular openings of 10 µm are randomly arranged in total, and the average value of the shortest distances between the center coordinates of each of the openings is 12.0 µm. This unit cell prepared a two-tone photomask arranged at 10 mm intervals on the entire surface of an area of 100 mm x 100 mm on a 6 inch square (about 152 mm angle) quartz substrate.

On the other hand, "P70BK" manufactured by Tokyo Okagyo Co., Ltd., a photoresist in which black pigments were mixed positively on a 100 mm x 100 mm glass substrate, was spin-coated so as to have a thickness of about 1.1 m after prebaking. The glass substrate with a photoresist film thus obtained was placed on a hot plate set at 85 ° C. for 120 seconds, and prebaking was performed. On this photoresist film, the photomask prepared above is maintained so that an exposure gap may be 120 micrometers, and g line | wire, h line | wire, and i line | wire multi-line light from an ultrahigh pressure mercury lamp which is an exposure light source are exposed through the photomask to g line | wire. Irradiation was carried out so that it might become 240 mJ / cm <^{2> in} conversion, and proximity exposure was performed. The glass substrate with a photoresist film after exposure was developed by the 23 degreeC 0.5% potassium hydroxide aqueous solution, and then rinsed with pure water. Then, the resin layer in which many recessed parts were formed in the surface was heated (post-baked) for 20 minutes in oven heated at 180 degreeC.

The nickel film was formed on the resin layer with recesses obtained in this way by the vapor deposition method, and the conductive process of the surface of the resin layer was performed. Next, the nickel film was formed in this electrically conductive process surface so that it might become thickness of about 0.3 mm by electroforming. The back surface of the nickel film was ground and polished in such a state that the nickel film adhered on the resin layer with recesses, and the film thickness was 0.15 mm. The nickel film after grinding | polishing was peeled from the resin layer with recesses, and the nickel plate which has many protrusions on the surface was manufactured.

Furthermore, the ultraviolet-curable resin "GRANDIC PC 806T2" made by Dainippon Ink & Chemical Co., Ltd. was melt | dissolved in ethyl acetate so that it might become 50% concentration, and the coating liquid was produced. This coating liquid was applied on a triacetyl cellulose film so that the film thickness after drying might be about 5 micrometers, and it dried for 3 minutes in 60 degreeC oven. In addition, after pressing the rubber roll so that the convex surface of the nickel plate with protrusions prepared above is in contact with the application surface of the ultraviolet curable resin, the light of the electroless type UV lamp on the triacetyl cellulose film side is 100 mJ in the amount of h-line conversion light. The ultraviolet curable resin was cured by irradiating to / cm ² . The triacetyl cellulose film was peeled off from the nickel plate for every cured resin, and the transparent anti-glare film containing the laminated body of the cured resin which has unevenness | corrugation on the surface, and a triacetyl cellulose film was obtained.

The surface shape of this anti-glare film was measured in the area | region of about 480 micrometers x 640 micrometers by the non-contact three-dimensional surface shape and roughness measuring instrument "New View 5010" made by Zygo Corporation mentioned above. And the height information of this anti-glare film was converted into grayscale, and displayed, and the data shown in FIG. 12 was obtained. Moreover, the area of each recess was calculated | required from this height information by the method mentioned above, and the bar graph of the recessed area shown in FIG. 13 was obtained. The maximum value of the concave area observed at this time was about 584 µm ² and the minimum was about 5 µm ² , and the interval between the areas during bar graph preparation was 10 µm ² . Next, the frequency x area was computed by the method mentioned above, and the bar graph of the apparent area shown in FIG. 14 was obtained. In this bar graph, a peak (maximum value) was observed at the divided portion between 40 μm ² and 50 μm ² . When the peak half value width was determined by the bar graph of the apparent area shown in FIG. 14, the peak half width was 30 µm ² , which was smaller than 100 µm ² . Therefore, this film has a small distribution of the apparent area of irregularities.

The obtained anti-glare film was placed on a high-precision liquid crystal panel of 200 ppi, and illuminated by backlight from the back, the glare was checked and evaluated visually, and no glare was observed. Moreover, the reflectance of the reflection direction of this anti-glare film in the normal reflection direction was 0.92%, and the reflectance of the direction twisted 20 degrees to the film side from the regular reflection angle was 0.00025%.

The triacetyl cellulose surface of this anti-glare film was bonded to glass, the opacity was measured, and the reflection sharpness at the time of 45 degrees incidence using the optical body of 1.0 mm in the width | variety of a dark part and a wrist was measured. As a result, it was confirmed that opacity was 8.0%, reflection clarity was 44.5%, and had low opacity and high projection prevention ability. In addition, the transmissive clarity using the optical body of 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm of the width | variety of a dark part and a lance was measured about the anti-glare film of the state bonded to glass similarly, and these four types were the following values, respectively. The total value of the transmission sharpness of was 297.4%, and it was confirmed that it has high sharpness.

0.125 mm optics: Transmission clarity 70.5%

0.5 mm optics: Transmission clarity 75.0%

1.0 mm optics: Transmission clarity 75.6%

2.0 mm optics: Transmission clarity 76.3%

----------------------------------

Total 297.4%

The above evaluation and measurement data in Example 1 are summarized in Table 1.

<Example 2>

In an area of 10 mm x 10 mm, three kinds of circular openings having a diameter of 8 µm, 9 µm, and 10 µm are randomly arranged in total, 588,069, and the average value of the shortest distances between the center coordinates of each opening is 11.6 µm. An anti-glare film was produced in the same manner as in Example 1 except that the prepared unit cells used two-tone photomasks arranged at 10 mm intervals on the entire surface of 100 mm × 100 mm area. When the distribution of the apparent area of the concave formed on the surface of the obtained film was evaluated, the peak (maximum value) of "area x frequency" was 60 µm ² and It observed in the division part between 70 micrometer <^2> , and the half value width of the peak was 30 micrometer <^2> . In addition, when the glistening was visually confirmed in the same manner as in Example 1, the glistening was not observed. In addition, the other optical characteristics of this anti-glare film are as showing in Table 1.

&Lt; Comparative Example 1 &

With respect to the antiglare film "AG6" sold by Sumitomo Kagaku Kogyo Co., Ltd., the distribution of the apparent area of the convex formed on the surface was evaluated in the same manner as in Example 1, and the peaks were 20 µm ² and 30 µm ² . It observed in the division part in between, The half width of the peak was 140 micrometer <^2> . In addition, when the glare was visually evaluated in the same manner as in Example 1, the glare was observed and difficult to see. Other optical characteristics of this anti-glare film are as showing in Table 1.

Comparative Example 2

With respect to the antiglare film "GH5" sold by Sumitomo Kagaku Kogyo Co., Ltd., the distribution of the apparent area of the convex formed on the surface was evaluated in the same manner as in Example 1, and the peaks were 10 µm ² and 20 µm ² . It was observed in the divided part between and the half width of the peak was larger than 300 micrometer <^2> . In addition, when the naked eye evaluated the sparkle, the sparkle was observed and difficult to see. Other optical characteristics of this anti-glare film are as showing in Table 1.

Apparent area distribution Optical properties Visual evaluation peak Half width 20 ° twisted
reflectivity Opacity Reflection Transmission sharpness glitter Example 1 40-50 μm ² 30 μm ² 0.00025% 8.0% 44.5% 297.4% ○ Example 2 60 ~ 70 ㎛ ² 30 μm ² 0.00019% 5.9% 21.8% 311.0% ○ Comparative Example 1 20 ~ 30 ㎛ ² 140 μm ² 0.00670% 32.4% 4.7% 31.7% × Comparative Example 2 10-20 μm ² > 300 μm ² 0.00046% 49.4% 4.4% 57.4% ×

Note: Transparency sharpness is a total of four types.

<Example 3>

233,624, 196,085 and 158,627 circular openings each having a diameter of 8 µm, 9 µm and 10 µm are arranged in a 10 mm by 10 mm angle region, and the average value of the distances between the center coordinates of the nearest openings is 15 µm. The unit cell was designed to be. This unit cell prepared a two-tone photomask arranged in a square lattice at 10 mm intervals over a 100 mm x 100 mm area front on a quartz substrate having one side 6 inches (one side about 152 mm). The average diameter of the opening portion in this photomask is calculated to be 8.9 μm by the above expression (2).

On the other hand, the film thickness after prebaking "P70BK" (brand name) by Tokyo Ogyo Co., Ltd. which is a photoresist in which black pigment was mixed positively on the glass substrate of 100 mm x 100 mm square is about 1.1 micrometers. Spin coating was made. The obtained glass substrate with a photoresist film was put on the hotplate heated at 85 degreeC for 120 second, and prebaking was performed. The photomask is maintained on the photoresist film so that the exposure gap is 120 µm, and the g-line, h-line, and i-line multi-line light from the ultra-high pressure mercury lamp, which is an exposure light source, is converted into g-line through the photomask. Irradiance was performed by irradiating so that the exposure light amount of 240 mJ / cm <^2> may be sufficient. The relationship L / D ² between the exposure gap L at this time and the average diameter D of the opening portion is calculated to be 1.51. The glass substrate with a photoresist film after exposure was immersed in 23 degreeC 0.5% potassium hydroxide aqueous solution for 80 second, developed, and then rinsed with pure water. Then, the photoresist layer in which the unevenness | corrugation was formed in the surface was obtained by heating for 20 minutes and post-baking in oven heated at 180 degreeC.

The nickel film was formed on the uneven surface of the obtained photoresist layer with unevenness | corrugation by the vapor deposition method, and the electroconductive process of the surface of the photoresist layer was performed. Next, a nickel film was formed on this conductive surface so as to have a thickness of about 0.3 mm by electroforming. The surface of the nickel film was ground and polished in such a state that the nickel film adhered to the uneven surface of the photoresist layer so that the film thickness was 0.2 mm. The nickel film after polishing was peeled from the photoresist layer to prepare a nickel plate having a large number of irregularities on the surface.

Separately, the photocurable resin composition "Grandic 806T" (trade name) manufactured by Dainippon Ink Chemical Industries, Ltd. was dissolved in ethyl acetate to prepare a coating solution having a concentration of 50%. This coating liquid was applied onto a triacetyl cellulose (TAC) film having a thickness of 80 µm so that the coating thickness after drying was 5 µm, and dried for 3 minutes in a dryer set at 60 ° C. The film after drying was pressed by the rubber roll so that the photocurable resin composition layer might become the nickel plate side to the uneven surface of the nickel plate which has an unevenness | corrugation on the surface produced above. In this state, the light from the high-pressure mercury lamp of 20 mW / cm ² intensity | strength was irradiated so that it might become 200 mJ / cm <^2> by h line conversion light quantity, and the photocurable resin composition layer was hardened on the TAC film side. Thereafter, the TAC film was peeled off from the nickel plate for each cured resin to obtain a transparent antiglare film including a laminate of a cured resin having irregularities on the surface and a TAC film.

When the reflected light by the obtained anti-glare film was visually observed, coloring of the reflected light was not confirmed.

The antiglare film of the present invention is particularly useful for increasing the visibility of image display devices including liquid crystal displays.

The anti-glare film produced by the above method arbitrarily controls the size and shape of the pattern in the photomask used for photolithography, and also controls the exposure conditions at that time. The characteristic becomes excellent. Therefore, this anti-glare film is useful for improving the anti-glare performance of various display devices including a liquid crystal display device.

1 main plane of antiglare film,
2 projection surface of film,
3 convex (area higher than the average height) of the film surface,
4 concave of the film surface (area lower than the average height),
5 The main law of film,
6 incident light directions,
7 the surface containing the main normal and the incident light direction of the film,
8 specular reflection direction,
9 20 ° twisted from the specular angle,
ψ incident angle (= specular reflection angle),
11 substrate for forming photoresist film,
12 photoresist film,
13 photoresist film formed with irregularities,
14 photomask,
15 luminous flux after passing through the photomask,
17 electric molded metal,
18 embossing moulds,
20 antiglare film,
21 transparent substrate film,
22 ultraviolet curable resins or cured products thereof,
25 normal direction of the antiglare film,
26 the plane containing the normal and the incident light direction of the antiglare film,
30 incident beam directions,
32 specular reflection direction,
34 direction inclined by the angle θ from the specular reflection direction to the antiglare film,
ψ incident angle (= specular reflection angle),
angle of inclination from the specular reflection direction to the antiglare film side.

Claims (7)

A lithography step of forming irregularities on the photoresist film formed on the substrate by photolithography;
An electroforming mold manufacturing process of electroforming a metal on the concave-convex surface of the obtained photoresist film, transferring the concave-convex shape to a metal, and then peeling a metal plate on which the concave-convex shape is transferred from the photoresist film to manufacture a mold; ,
As a manufacturing method of the anti-glare film which has an unevenness | corrugation on the surface using the metal plate which uneven | corrugated shape was transferred in this way as a metal mold | die, and including the uneven | corrugated film manufacturing process which transfers the uneven | corrugated shape of the surface to the surface of a film,
The lithographic process is performed by exposing a photoresist film through a photomask having two or more patterns having different diameters of the transmissive portion or the light shielding portion in the mask, and then developing the antiglare film. The method according to claim 1, wherein the photomask is formed with a pattern such that the ratio of the diameter of the largest pattern to the diameter of the smallest pattern is 1.1 to 2 times. The photomask of claim 1 or 2, wherein the photomask is formed such that a ratio between the total areas occupied by each of the transmissive portions or the light shielding portions forming two or more patterns having different diameters of the transmissive portions or the light shielding portions is in a range of 0.7 to 1.3. That way. The method according to claim 1 or 2, wherein the exposure through the photomask is performed by proximity exposure in which the photomask is spaced apart from the surface of the photoresist film. The method according to claim 4, wherein the distance between the photomask and the surface of the photoresist film is L (μm), the average diameter of the pattern of the photomask is D (μm), and the value of L / D ² is 1.3 or more and 2.8 or less. A method of performing exposure under conditions. The method according to claim 1 or 2, wherein the photomask is configured by arranging a plurality of unit cells arranged in a predetermined area such that translational symmetry is maintained. The method of Claim 1 WHEREIN: The method of winding up the metal plate which the uneven | corrugated shape was transcribe | transferred on the surface of a roll, and sending it to a uneven | corrugated film manufacturing process.

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