JP4100350B2 - Method for producing antiglare film - Google Patents

Description

  The present invention relates to a method for producing an antiglare film suitably used for optical applications such as a polarizing film in an image display device. Specifically, the present invention relates to a method suitable for producing an antiglare film effective for obtaining a specific reflection profile.

  In an image display device such as a liquid crystal display device, when external light is reflected on the image display surface, the visibility is remarkably impaired. Reflective liquid crystal display devices such as TVs and personal computers that emphasize image quality, video cameras and digital cameras that are used outdoors with strong external light, and mobile phones that display using reflected light In such applications, the surface of the display device is generally treated to prevent such reflection. Reflection prevention processing is broadly divided into antireflection processing using interference by an optical multilayer film and so-called anti-glare processing that scatters incident light by forming fine irregularities on the surface and blurs the reflection image. . The former non-reflective treatment is costly because it is necessary to form a multilayer film having a uniform optical film thickness. On the other hand, since the latter anti-glare process can be realized at a relatively low cost, it is used for applications such as large personal computers and monitors.

  For example, an anti-glare film can be coated with a UV curable resin with a filler dispersed on a transparent substrate, dried, and then irradiated with UV to cure the resin, forming random irregularities on the film surface. It is manufactured by the method of doing.

  On the other hand, in JP-A-6-16851 (Patent Document 1) and JP-A-7-124969 (Patent Document 2), a transparent substrate having an ultraviolet curable resin layer on a film provided with an uneven shape in advance. A method is disclosed in which UV light is irradiated to the ultraviolet curable resin layer in a state in which is adhered to the ultraviolet curable resin layer side to transfer the uneven shape to the ultraviolet curable resin. However, Patent Document 1 only discloses a film on which a resin composition composed of a filler and a binder is applied on a base film as a film provided with an uneven shape in advance, and Patent Document 2 discloses a filler. There are only disclosed a method of stretching a film internally added with and a method of subsequent sandblasting the film.

  Japanese Patent Laid-Open No. 2002-365410 (Patent Document 3) discloses an optical film having fine irregularities formed on the surface, and a light beam is applied to the surface of the film from a direction of −10 ° with respect to the normal. An antiglare film is disclosed in which the profile of reflected light when incident and only the reflected light from the surface is observed satisfies a specific relationship.

JP-A-6-16851 (Claim 1, paragraph 0036) JP 7-124969 A (Claim 1, paragraph 0017) JP 2002-365410 A (Claim 1)

  Conventionally known anti-glare treatment films, particularly anti-glare films obtained by dispersing fillers, were unable to form irregularities of a desired size at desired locations. In addition, since the fillers are randomly arranged by coating, a density distribution of the fillers, and consequently, a density distribution of unevenness formed on the surface is generated. Further, in industrial production, filler aggregation is likely to occur, and unevenness may occur due to the aggregation. Furthermore, the same problem has occurred in the method in which the film having unevenness obtained as described above is used as an original and the shape is transferred to another film.

  On the other hand, in an anti-glare film used for an image display device, it is preferable that there are a plurality of irregularities in one pixel. Therefore, the size of each irregularity is smaller than the size of the pixel of the image display device to be applied. There is a need to. In addition, it is necessary to design the shape and arrangement of the unevenness so that the reflection of light by the unevenness of such size is optimal. In this case, the geometrical optical due to the shape of each unevenness is reflected on the reflected light. It is necessary to take into account the wave optical elements such as interference and diffraction of light due to the small size of the element and the unevenness. For example, in an anti-glare film that can be applied to an image display device such as a liquid crystal display device or a plasma display panel, when unevenness of the same size is randomly arranged in several μm to several tens of μm, the size of the unevenness is small. Interference and diffraction due to the same occur, and as a result, there arises a problem that the reflected light due to the unevenness of the surface looks like a rainbow color or the reflected light looks strong at a certain reflection angle.

  In Japanese Patent Application No. 2004-4308 (priority claim: Japanese Patent Application No. 2003-8744), the inventors of the present invention have a step of forming irregularities on a photoresist formed on a substrate by photolithography, and the obtained photoresist. After electroforming metal on the uneven surface of the film, peeling the metal from the photoresist and transferring the uneven shape on the photoresist to the metal, and using the uneven metal plate as a mold, The method of manufacturing the anti-glare film which has an unevenness | corrugation on the surface through the process to transfer is proposed.

  An object of the present invention is to provide a method capable of producing an antiglare film having excellent optical properties by controlling the unevenness formed on the surface. As a result of further research based on the method proposed in the above-mentioned Japanese Patent Application No. 2004-4308 for such purposes, the present inventor devised a photomask in the step of forming irregularities by photolithography, The inventors have found that a high-performance antiglare film can be obtained, and have completed the present invention.

  That is, according to the present invention, a lithography process for forming irregularities by photolithography on a photoresist film formed on a base material, and electroforming metal on the irregular surface of the obtained photoresist film to form the irregularities. After the transfer to the metal, the metal plate on which the concavo-convex shape is transferred is peeled from the photoresist film to produce a mold, and the metal plate thus transferred with the concavo-convex shape is used as a die. A method for producing an antiglare film having irregularities on the surface, the method comprising: producing an irregular film for transferring the irregular shape of the surface to the surface of the film, wherein the lithography step has at least two types of patterns having different sizes A method is provided that is performed by exposing a photoresist film through a photomask and then developing.

  In this method, the photomask is advantageously patterned so that the ratio of the largest pattern diameter to the smallest pattern diameter is 1.1 to 2 times. The photomask is advantageously formed with patterns so that the ratio of the total area occupied by at least two types 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 arranged at a distance from the surface of the photoresist film. Further, in this exposure, the distance between the photomask and the photoresist film surface is L (μm), the average diameter of the photomask pattern is D (μm), and the value of L / D ² is 1.3 or more and 2.8 or less. It is advantageous to carry out under such conditions.

  The photomask can be formed by arranging a plurality of unit cells having a predetermined area so that translational symmetry is maintained. In addition, when using a metal plate to which the concavo-convex shape is transferred as a mold and transferring the concavo-convex shape onto the surface of the film, the metal plate is wound around the surface of the roll so that the concavo-convex surface is on the outside. It can also attach to an uneven | corrugated film preparation process.

  According to the present invention, an antiglare film having excellent optical properties can be produced with good productivity and good reproducibility.

  Hereinafter, the present invention will be described in detail. In the present invention, a lithography process for forming irregularities by photolithography on a photoresist film formed on a substrate, and electroforming metal on the irregular surface of the obtained photoresist film, and transferring the irregularities to the metal. After that, an electroformed mold manufacturing process for producing a mold by peeling the metal plate with the concavo-convex shape transferred from the photoresist film, and using the metal plate with the concavo-convex shape transferred as a mold, An anti-glare film is manufactured through the uneven | corrugated film preparation process which transcribe | transfers a shape to the surface of a film. These steps will be described with reference to FIG. In FIG. 1, the steps shown in (A), (B) and (C) correspond to the above-mentioned lithography step as a whole, and the steps shown in (D) and (E) as a whole are the above-mentioned electroforming mold manufacturing steps. And the steps shown in (F) and (G) correspond to the above uneven film manufacturing step as a whole.

  First, as shown in FIG. 1A, a photoresist film 12 is formed on the surface of a substrate 11 for forming a photoresist film. The base material 11 used here can be used without particular limitation as long as the surface is flat and the photoresist film adheres appropriately. For example, inorganic transparent base materials such as glass, quartz, and alumina, and metal base materials such as copper and stainless steel can be used. The photoresist applied on the substrate 11 may be any photo-sensitive photoresist having an appropriate resolution, and the exposed portion becomes soluble in the developer and removed after development. Either a resist or a negative photoresist in which an exposed portion is cured and becomes insoluble in a developer, and an unexposed portion is removed by development can be used. For example, a novolac resin, an acrylic resin, a copolymer of styrene and acrylic acid, an alkali-soluble resin such as polyvinylphenol or poly (α-methylvinylphenol), and a photosensitive compound such as a quinonediazide group-containing compound. Examples include a positive photoresist composition dissolved in an organic solvent, and a negative photoresist composition prepared by dissolving a photosensitive resin containing an alkali-soluble resin, a photoacid generator, a crosslinking agent, etc. in an organic solvent. It is done. However, in the subsequent exposure, a positive photoresist is preferred in order to cause light diffraction at the edge portion by proximity exposure and to form a rounded recess by subsequent development. The example shown below with reference to FIG. 1 is a case where a positive photoresist is used.

  The thickness of the photoresist film 12 formed on the substrate 11 may be appropriately adjusted depending on the depth and shape of the unevenness to be formed on the surface of the antiglare film, and is equivalent to the desired unevenness depth, or It is preferable to form a film slightly thicker than that. As a specific range of the film thickness, it is preferable to be not less than the depth of the target unevenness and not more than the depth of the target unevenness + 5 μm or less.

  In order to form the photoresist film 12 on the substrate 11, a known appropriate coating method such as a spin coating method, a dip coating method, or a roll coating method can be employed. After film formation, pre-baking is usually performed in order to remove the solvent contained in the photoresist. The pre-baking is performed, for example, using a hot plate or an oven at a temperature of about 60 to 120 ° C. for about 0.5 to 10 minutes. The pre-baking temperature and time can be appropriately adjusted depending on the type of photoresist and the sensitivity required for the photoresist.

  The photoresist film 12 thus formed on the substrate 11 is then subjected to gradation exposure through a two-gradation photomask 14 as shown in FIG. 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 the exposure light source, and a transmissive portion having a transmittance of 100% or close to it, and exposure. It is a portion that shields light from the light source and has a light shielding portion with a transmittance of 0% or close thereto. Specifically, for example, a metal mask in which a metal such as chromium is formed as a light-shielding portion on a substrate transparent to the exposure light source, or an emulsion mask in which a light-shielding portion is formed by exposing an emulsion or the like. .

  The light source used for exposure is not particularly limited as long as it can sensitize the photoresist film 12, and an appropriate light source is used according to the type of the photoresist. For example, using a high-pressure mercury lamp or an ultrahigh-pressure mercury lamp as a light source, using near ultraviolet rays such as g-line, h-line, and i-line, or using laser light having a transmission wavelength close to the emission line of these mercury can do. At the time of exposure, an optical member such as a lens system or a mechanical member such as a mask alignment system may be interposed between the exposure light source and the photoresist film as long as the effects of the present invention are not impaired. .

  The photoresist film 12 thus subjected to gradation exposure is then subjected to a development process, and a photoresist film 13 having irregularities is obtained as shown in FIG. In the development process, for example, the exposed photoresist film 12 formed on the substrate 11 is brought into contact with a developer corresponding to the type thereof, and in the case of a positive type photoresist, the exposed portion is removed to remove the photoresist. Unevenness is formed on the film 12. The developer can be appropriately selected from conventionally known ones according to the type of the photoresist. After the development, it is usually rinsed with water and further post-baked. By post-baking, the strength of the remaining photoresist film can be improved and the adhesion to the substrate 11 can be improved. In the case of a positive type photoresist, this post-bake also acts to deactivate the photosensitivity of the unexposed residual film portion. The post-baking is performed, for example, using an oven or a hot plate at a temperature of about 100 to 200 ° C. for a time of about 0.5 to 30 minutes.

  Next, as shown in FIG. 1D, the metal film 17 is electroformed on the photoresist film 13 with the irregularities formed thereon, and the irregularities on the surface of the photoresist film 13 are transferred to the electroformed metal 17. . The metal used for electroforming may be conventionally used in the field of electroplating, and examples thereof include nickel, nickel-phosphorus alloy, iron-nickel alloy, chromium, and chromium alloy. 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 from the viewpoint of durability. When electroforming directly on the photoresist film 13, it is necessary to make the surface of the photoresist film 13 conductive before electroforming. For example, a metal film having a thickness of 1 μm or less is deposited or evaporated. It can be performed by a method of forming by sputtering or the like or a method of electroless plating. When 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 formed by transferring the concave shape on the photoresist film 13 to the metal 17. When it is desired to transfer the same material to the metal 17 to form a concave shape, for example, after transferring the concave / convex shape formed on the photoresist film 13 to the resin, the concave / convex surface of the resin is transferred by the method described above. A method of conducting a conductive treatment and electroforming the same can be employed.

  The metal plate 17 to which the unevenness from the photoresist film 13 has been transferred is then peeled off from the photoresist film 13, or when the unevenness of the photoresist film 13 is transferred to a resin and electroformed there The metal plate 18 having irregularities formed on the surface as shown in FIG.

  The metal plate 18 with the unevenness formed on the surface thus obtained is used as a mold, and the unevenness formed on the surface is transferred to the surface of the film 20 to obtain an antiglare film. In the example shown in FIGS. 1F and 1G, an ultraviolet curable resin 22 is applied on the transparent substrate film 21, and the ultraviolet curable resin 22 side is adhered to the uneven surface of the mold 18. In this state, the ultraviolet curable resin 22 is cured by irradiating ultraviolet rays from the transparent substrate film 21 side, and the layer of the ultraviolet curable resin 22 having irregularities is formed on the transparent substrate film 21. A film 20 is obtained. Not only in this example, but also by a method in which a thermoplastic transparent resin film is pressed against the mold 18 in a heated state and shaped, an antiglare film having irregularities formed on the surface can be obtained.

  When the ultraviolet curable resin 22 is applied on the transparent base film 21 and the unevenness is transferred to the ultraviolet curable resin 22 side as shown in the example shown in FIGS. As the curable resin, any commercially available resin can be used. For example, polyfunctional acrylates such as trimethylolpropane triacrylate and pentaerythritol tetraacrylate are used alone or in admixture of two or more thereof, and “Irgacure 907”, “Irgacure 184” (above, Ciba A product obtained by mixing a photopolymerization initiator such as “Specialty Chemicals” or “Lucirin TPO” (BASF) can be used as an 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 is adopted, any thermoplastic transparent resin film can be used as long as it is substantially transparent. For example, a solvent cast film or an extruded film of a thermoplastic resin such as amorphous cyclic polyolefin using a monomer of polymethyl methacrylate, polycarbonate, polyethylene terephthalate, triacetyl cellulose, or norbornene compound is used. be able to. These transparent resin films can also be used as the transparent base film 21 when the ultraviolet curable resin described above is used.

  In the present invention, the photomask 14 having at least two types of patterns having different sizes is used in the lithography process, particularly in the exposure process shown in FIG. The pattern here is an individual transmission part (opening) or light shielding part having a size sufficiently larger than at least the wavelength of exposure light. That is, a transmission portion and a light shielding portion having a size that is the same level as or smaller than the wavelength of the exposure light and that is sufficiently smaller than the wavelength of the exposure light using a high-resolution photomask drawing device such as an electron beam drawing device. It does not indicate a transmission part or a light shielding part that is sufficiently smaller than the wavelength of the exposure light in the case of providing a gradation mask by expressing the gradation by the area ratio between the transmission part and the light shielding part. In the present invention, the size of a pattern is defined as the diameter of a circle that gives the same area as the area of the pattern.

  When a two-tone photomask having a pattern of the same size is used, the shape of the unevenness formed on the photoresist film by photolithography has substantially the same size. As described above, in consideration of the size of pixels in an image display device such as a liquid crystal display device or a plasma display panel, when the patterns formed on the photoresist film are almost the same size, the unevenness is formed by electroforming. Even after the transfer to the plate and the unevenness of the metal plate to the film, the unevenness on the film is almost the same size. It tends to appear colored.

  In the present invention, since photolithography is performed using a photomask having a pattern with a different size, the shape formed on the photoresist film has various sizes. Are less likely to occur, and the phenomenon that the reflection of colored light due to surface irregularities or the reflectance of light of a specific wavelength at a specific angle increases is reduced.

  In this photomask, if the difference in pattern size is too small, the unevenness formed on the photoresist film becomes almost the same size, and the effect intended by the present invention is not sufficiently exhibited, If the difference in pattern size is too large, the density of the place where the pattern is present and the place where the pattern is absent on the photomask becomes too large, and it tends to be difficult to achieve uniform anti-glare properties. Therefore, the size of the pattern formed on the photomask should be 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. preferable. The pattern size ratio is preferably 1.2 times or more and 1.5 times or less, and more preferably 1.3 times or less. Each pattern preferably has a diameter in the range of 1 to 50 μm depending on the display device to which the target antiglare film is applied, and more preferably 5 μm or more and 30 μm or less. More preferably.

  It is preferable that the total area of the patterns having different sizes on the photomask is not so different between the patterns. That is, for example, when a pattern X having a certain size and a pattern Y having a different size are mixed, the ratio of the total area of the pattern X to the total area of the pattern Y is in the range of about 0.7 to 1.3. It is preferable that When three or more types of patterns having different sizes are mixed, it is only necessary to satisfy such a relationship between any two types of patterns. It is more preferable to satisfy this relationship.

  Further, as shown in FIG. 1B, it is preferable to perform proximity exposure by arranging a two-tone photomask 14 at a slight distance from the surface of the photoresist film 12. Proximity exposure means that the photomask 14 is brought close to the photoresist film 12 as described above, but is not closely contacted, and is arranged and exposed at a slight interval. Proximity exposure using such a two-tone photomask 14 causes diffraction of light at the edge portion of the mask pattern of the photomask 14 as schematically shown in FIG. The image of the photomask 14 is blurred, and the light beam 15 that has passed through the transmission part spreads over the back surface of the light shielding part, resulting in a continuous light quantity distribution. Then, since the photoresist film 12 is exposed in accordance with the distribution of the light quantity subjected to the proximity exposure, the subsequent development changes the remaining photoresist film thickness in accordance with the irradiation light quantity, and the surface of the photoresist film 12 after development. Asperities are formed according to the mask pattern, the exposure amount, the distance between the photomask and the photoresist film (referred to as “exposure gap” or “proximity gap”), and the like.

In performing proximity exposure using the 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 photomask pattern is D (μm) In addition, it is preferable to perform exposure under conditions such that the value of L / D ² is 1.3 or more and 2.8 or less, that is, conditions that satisfy the following expression (1).

1.3 ≦ L / D ² ≦ 2.8 (1)

The relationship between the distance L between the photomask and the photoresist film and the average diameter D of the photomask pattern will be described with reference to FIG. 2 which is an enlarged view of part of FIG. As shown in this figure, the interval between the photomask 14 and the surface of the photoresist film 12 is L. In the present invention, since a photomask having at least two types of patterns having different sizes is used, for example, assuming that the photomask 14 has three types of patterns, the diameters of the respective patterns are set to D ₁ , D ₂ and D ₃ The average diameter D of the patterns is a weighted average that takes into account the size and number of each of these different types of patterns. In the case of having three types of patterns with diameters D ₁ , D ₂ and D ₃ as shown in FIG. 2, the total number of patterns in the entire photomask or unit area is N ₁ , N ₂ and N _{When the} number is ₃ , the average diameter D is calculated by the following equation (2).

Now, the spread of the image of the light that has passed through the minute opening changes according to the index (L / D ² · λ) consisting of the distance L between the opening and the photoresist film, the opening dimension D, and the wavelength λ of the light. However, when the gap between the opening and the photoresist film is small, the shape of the opening is transferred almost as it is onto the photoresist film, whereas as the gap between the opening and the photoresist film increases, the photoresist film The diffused light around the optical axis is irradiated on the top. 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 sharply corresponding to the opening shape. Therefore, through holes are easily formed in the photoresist film, and the light scattering function of the antiglare film obtained therefrom tends to be lowered. On the other hand, if the value of L / D ² is too large, the light diffracted by the photomask diffuses, and it tends to be difficult to form a pattern on the surface of the photoresist film. It has been confirmed by experiments that a generally good exposure image can be formed if the value of L / D ^{2 is in} the range of 1.3 to 2.8.

  In the description with reference to FIG. 1, according to (A) to (E), the photoresist film 12 is subjected to gradation exposure and developed to form a concavo-convex pattern, and finally on the film. The antiglare film 20 having the uneven shape transferred continuously is produced. For this reason, it is necessary to design a mask pattern in order to produce the original photomask 14. Designing such a mask pattern over the entire surface of the photomask 14 is a very time-consuming work, and since the data capacity of the mask pattern increases, the burden on the mask drawing machine also increases. Considering the ability of a computer, although it is possible in principle, it is not always realistic. Therefore, it is advantageous to design a mask pattern that constitutes a unit cell having a predetermined area, and to arrange a plurality of such unit cells so as to maintain translational symmetry so that a photomask covering the entire surface of the photoresist film 12 is obtained. It is. By adopting such a method, it is possible to reduce time and effort for designing the mask pattern of the photomask 14 as a whole, which is industrially advantageous. Here, the translational symmetry means that the unit cells are arranged in a certain direction such as front and rear, right and left direction or diagonal direction. As an example of a state in which the mask pattern is arranged so as to maintain translational symmetry, the barycentric coordinates of each unit cell are arranged in a lattice shape such as a square lattice shape, a rectangular lattice shape, an oblique lattice shape, or a hexagonal lattice shape. State.

  In a photomask having at least two types of patterns having different sizes, at least two types of patterns may be used, and the upper limit of the types is not particularly limited. However, as the number of types of patterns increases, the data capacity for designing a mask pattern also increases. Therefore, in practice, it is preferable to appropriately select the pattern type from the range of about 2, 3, 4 and 5 types according to the target performance.

  In addition, the metal plate (mold) 18 with the irregularities formed as described above is wound around a roll, or the mold 18 is wound around in a state where a plurality of such molds 18 are arranged on the roll surface as necessary. A method is also suitable in which an embossed roll having irregularities is prepared and the irregular shape is continuously transferred to the film surface using the embossed roll. By adopting such a method, the concavo-convex shape can be continuously and efficiently transferred to a film having a large area, and high productivity can be ensured.

  As described above, exposure is performed through a photomask having at least two types of patterns having different sizes, and irregularities are formed by photolithography to be developed, and a metal mold is produced by electroforming metal thereon, By the method of transferring irregularities on the film surface using the mold, an antiglare film having fine irregularities formed on the surface, good antiglare performance and excellent optical characteristics can be produced. At this time, the antiglare performance and optical characteristics can be controlled by appropriately selecting conditions such as a photomask pattern, exposure amount, and exposure gap.

  In the present invention, a method of producing a mold having fine irregularities by combining the formation of irregularities by photolithography and electroforming of metal thereon, and transferring the irregularities to the surface of the film using the mold. Since it was adopted, an antiglare film having a uniform distribution of unevenness that affects antiglare properties and exhibiting high performance can be produced with good productivity. Specifically, for example, the reflectance (regular reflectance) in the regular reflection direction with respect to incident light incident at an angle of 5 to 30 ° from the normal direction of the antiglare film is R (0), and regular reflection is performed. When the reflectance with respect to incident light at an angle θ inclined from the direction toward the antiglare film side is R (θ), the reflection profile in which the θ dependence of R (θ) is plotted is monotonously reduced. Easy to get.

  The concept of this reflection profile measurement is shown in FIG. That is, the regular reflection direction means that when the light beam 30 is incident at an angle ψ with respect to the normal direction 25 of the antiglare film 20, the incident light direction 30 within a plane 26 including the normal 25 and the incident light direction 30. Means the direction of the light 32 reflected at an angle ψ in the opposite direction. ψ is an incident angle, which is also a regular reflection angle, but strictly speaking, the sign is reversed. The reflectance in the regular reflection direction 32 with respect to the incident light from the incident light direction 30 is the regular reflectance R (0). When the incident angle ψ is arbitrarily set between 5 ° and 30 °, the angle from the regular reflection direction 32 to the anti-glare film 20 side in the plane 26 including the film normal direction 25 and the incident light direction 30 The reflectance with respect to the incident light is measured in the direction 34 inclined by θ, and this is defined as R (θ). When the inclination angle θ is changed between 0 ° (that is, the regular reflection direction) and 90 ° −ψ (that is, the direction parallel to the film surface), the reflectance R (θ) is measured and plotted for each inclination angle θ. Generally, R (θ) when θ = 0 °, that is, R (0) is maximized. In the graph of the reflectivity R (θ) with respect to the tilt angle θ, the method of the present invention gives a profile in which the θ dependency of R (θ) is monotonously reduced as schematically shown in FIG. Easy to get.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples,% representing the content or amount used is based on weight unless otherwise specified.

Example 1
233,624, 196,085, and 158,627 circular openings with diameters of 8 μm, 9 μm, and 10 μm are arranged in a 10 mm × 10 mm square region, and the distance between the center coordinates of the closest openings The unit cell was designed so that the average value of was 15 μm. A two-tone photomask was prepared in which the unit cells were arranged in a square grid pattern with a period of 10 mm over the entire area of 100 mm × 100 mm on a 6-inch square (about 152 mm square) quartz substrate. The average diameter of the openings in this photomask is calculated as 8.9 μm from the above equation (2).

On the other hand, “P70BK” (trade name) manufactured by Tokyo Ohka Kogyo Co., Ltd., which is a positive-type photoresist mixed with a black pigment on a 100 mm × 100 mm square glass substrate, has a film thickness of about 1 after pre-baking. It was spin-coated so as to have a thickness of 1 μm. The obtained glass substrate with a photoresist film was placed on a hot plate heated to 85 ° C. for 120 seconds, and prebaked. On this photoresist film, the above-mentioned photomask is held so that the exposure gap becomes 120 μm, and through the photomask, a multi-line of g-line, h-line and i-line from an ultra-high pressure mercury lamp which is an exposure light source Proximity exposure was performed by irradiating light so as to obtain an exposure light amount of 240 mJ / cm ^{2 in} terms of g-line. The relationship L / D ² between the exposure gap L and the average diameter D of the opening at this time is calculated as 1.51. The exposed glass substrate with a photoresist film was developed by immersing in a 0.5% aqueous potassium hydroxide solution at 23 ° C. for 80 seconds, and then rinsed with pure water. Then, the photoresist layer in which the unevenness | corrugation was formed on the surface was obtained by heating for 20 minutes in the oven heated at 180 degreeC, and post-baking.

  A nickel film was formed on the concavo-convex surface of the photoresist layer with concavo-convex thus obtained by vapor deposition, and the photoresist layer surface was subjected to a conductive treatment. Next, a nickel film was formed on the conductive surface so as to have a thickness of about 0.3 mm by electroforming. With the nickel film adhered to the uneven surface of the photoresist layer, the back surface of the nickel film was ground and further polished to a thickness of 0.2 mm. The nickel film after polishing was peeled off from the photoresist layer to produce a nickel plate having a large number of irregularities on the surface.

Separately, a photocurable resin composition “Grandic 806T” (trade name) manufactured by Dainippon Ink & Chemicals, Inc. was dissolved in ethyl acetate to prepare a 50% concentration coating solution. This coating solution was applied onto an 80 μm thick triacetylcellulose (TAC) film so that the coating thickness after drying was 5 μm, and dried for 3 minutes in a drier set at 60 ° C. The dried film was brought into close contact with the uneven surface of the nickel plate having unevenness on the surface produced above by pressing with a rubber roll so that the photocurable resin composition layer was on the nickel plate side. In this state, light from a high-pressure mercury lamp having an intensity of 20 mW / cm ² was irradiated from the TAC film side so that the amount of light in terms of h-line was 200 mJ / cm ² to cure the photocurable resin composition layer. Thereafter, the TAC film was peeled off from the nickel plate together with the cured resin to obtain a transparent antiglare film comprising a laminate of the cured resin having irregularities on the surface and the TAC film.

  When the reflected light from the obtained antiglare film was observed visually, the reflected light was not colored.

  The antiglare film produced according to the present invention has a uniform quality even in a large area by arbitrarily controlling the size and shape of the pattern in the photomask used for photolithography and controlling the exposure conditions at that time. Thus, the antiglare performance and optical properties are excellent. Therefore, this antiglare film is useful for enhancing the antiglare performance of various display devices including liquid crystal display devices.

It is a cross-sectional schematic diagram which shows an example of the manufacturing method of the anti-glare film by this invention for every process. It is a cross-sectional schematic diagram which expands and shows a part of FIG. 1 (B). It is a perspective view for demonstrating the relationship between a regular reflectance and the reflectance to angle (theta) inclined toward the film side from the regular reflection direction. When R (0) is the reflectance at an angle θ inclined from the regular reflection direction to the film side and R (θ) is R (0), R (0) is the maximum. , Θ is a schematic graph showing a state of monotonously decreasing as θ increases.

Explanation of symbols

11 ... Substrate for forming a photoresist film,
12 …… Photoresist film,
13: Photoresist film with irregularities formed,
14 …… Photomask,
15 …… Exposure flux after passing through photomask,
17 …… Electroformed metal,
18 …… Mold with concavo-convex transferred,
20 ... Anti-glare film or its precursor,
21 …… Transparent substrate film,
22: UV curable resin or cured product thereof,
25 …… Normal direction of anti-glare film,
26 …… A surface including the normal line of the antiglare film and the direction of incident light,
30: Incident ray direction,
32 …… Specular reflection direction,
34... Direction inclined by angle θ from the regular reflection direction to the antiglare film side,
ψ ......... incident angle (= regular reflection angle),
θ: The angle of inclination from the regular reflection direction to the antiglare film side.

Claims (5)

A lithography step of forming irregularities by photolithography on the surface of the photoresist film formed on the substrate;
An electroforming mold in which a metal is electroformed on the concavo-convex surface of the obtained photoresist film and the concavo-convex shape is transferred to the metal, and then the metal plate to which the concavo-convex shape is transferred is peeled from the photoresist film to produce a mold. Mold making process;
A method for producing an antiglare film having irregularities on the surface, comprising using a metal plate to which the irregularities are transferred in this way as a mold, and an irregularity film forming step for transferring the irregularities on the surface to the surface of the film,
The lithography step may have at least two kinds of patterns different sizes, a pattern such that the ratio of the diameter of the largest pattern to the diameter of the smallest pattern becomes 2 times or less than 1.1 times is formed Producing an anti-glare film , wherein the photo resist film is exposed by proximity exposure through a photo mask and spaced apart from the surface of the photo resist film, and then developed. Method. 2. The method according to claim 1, wherein the photomask has a pattern formed so that a ratio of a total area occupied by at least two types of patterns having different sizes is in a range of 0.7 to 1.3 . Conditions where L / D ² is 1.3 or more and 2.8 or less, where L (μm) is the distance between the photomask and the photoresist film surface, and D (μm) is the average diameter of the photomask pattern. The method according to claim 1 or 2 , wherein the exposure is carried out in step (1). 4. The method according to claim 1 , wherein the photomask is configured by arranging a plurality of unit cells each having a predetermined area so that translational symmetry is maintained . The method according to any one of claims 1 to 4, wherein the metal plate to which the concavo-convex shape is transferred is wound around the surface of the roll and subjected to the concavo-convex film production step .

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