JP2016033617A - Antireflection article and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antireflection article with a moth-eye structure, and reduces reflection due to internal reflection compared to the conventional one.SOLUTION: There is provided an antireflection article 1 that has micro projections 5 arranged tightly close to each other, the interval between the adjacent micro projections 5 being equal to or less than the minimum wavelength of a wavelength band of a magnetic wave for preventing reflection, where the micro projections 5 are held on the surface of a substrate 2 made of a transparent film material via an intermediate holding layer 4, and the intermediate holding layer 4 includes, on the substrate side, a light diffusion layer 4B including light diffusion particles.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an antireflection article for preventing reflection by closely arranging a large number of minute protrusions at intervals equal to or shorter than the shortest wavelength of an electromagnetic wave wavelength band for preventing reflection.

  In recent years, regarding an antireflection film, which is a film-shaped antireflection article, there has been proposed a method for preventing reflection by arranging a large number of microprotrusions closely on the surface of a transparent substrate (transparent film) (patent) References 1-3). This method utilizes the principle of a so-called moth-eye structure, and the refractive index for incident light is continuously changed in the thickness direction of the substrate, whereby a discontinuous interface of refractive index is obtained. Is eliminated to prevent reflection.

  In the antireflection article according to this moth-eye structure, the microprojections are closely arranged so that the distance d between adjacent microprojections is equal to or less than the shortest wavelength Λmin (d ≦ Λmin) of the wavelength band of the electromagnetic wave to prevent reflection. The Moreover, each microprotrusion is produced so that a cross-sectional area may become small gradually toward the front end side from a transparent base material so that it may be planted on a transparent base material.

  Further, Patent Document 4 discloses a configuration in which the base portion of the microprojection is formed so as to exhibit undulation with a period larger than that of the microprojection with respect to this type of antireflection article. Further, this Patent Document 4 discloses a configuration in which this type of antireflection article is created by creating minute protrusions on the surface of a substrate by a molding process using a molding resin.

  By the way, when the conventional antireflection film is attached to the panel surface of the image display panel, the reflection on the outermost surface can be reduced, thereby reducing the reflection or the like and improving the visibility of the display screen. However, in the image display panel, for example, there is a boundary where the refractive index changes abruptly, such as the boundary between the glass substrate on the exit surface side constituting the liquid crystal cell and the film material. The light is reflected. As a result, even when an antireflection film is attached, there is a problem that reflection occurs due to the internal reflection and the quality of the display screen is impaired.

Japanese Patent Laid-Open No. 50-70040 Special Table 2003-531962 Japanese Patent No. 4632589 Japanese Patent No. 4794351

  The present invention has been made in view of such a situation, and an object of the present invention is to further reduce reflection due to internal reflection with respect to an antireflection article having a moth-eye structure as compared with the conventional art.

  The present inventor has intensively studied to solve the above-mentioned problems, and arrived at the idea that a light diffusing layer provided with light diffusing particles is provided in the vicinity of the boundary that causes the problematic internal reflection. It came to complete.

    Specifically, the present invention provides the following.

(1) In an antireflection article in which microprotrusions are closely arranged, and an interval between the adjacent microprotrusions is equal to or less than the shortest wavelength of the wavelength band of electromagnetic waves for antireflection,
The microprotrusions are held on the surface of the substrate by a transparent film material through an intermediate holding layer,
An antireflection article comprising a light diffusing layer comprising light diffusing particles on the substrate side of the intermediate holding layer.

  According to (1), the internal reflection light can be scattered at a location close to the generation source, and the internal reflection light can be efficiently scattered to reduce reflection due to internal reflection. In addition, since the reflection of light is reduced by the light diffusion layer and the moth-eye structure is formed on the surface, even if the internal reflection light is sufficiently scattered by the light diffusion layer, the resulting scattered light Scattering at the outermost surface can be sufficiently reduced. Thereby, a large amount of light diffusing particles in the light diffusing layer can be mixed to effectively reduce the reflection due to internal reflection, and the whiteness of the display screen due to the haze value deterioration can be effectively avoided.

(2) In (1),
The intermediate holding layer is
A resin layer for shaping to be subjected to a shaping treatment of the microprotrusions provided with the light diffusing particles,
In the molding resin layer, the inter-particle distance of the light diffusing particles is relatively shortened on the base material side to form the light diffusing layer,
In the molding resin layer, an antireflection structure in which a light-transmitting layer that suppresses scattering of transmitted light is formed on the microprotrusion side in which the distance between the light diffusion particles is relatively long on the microprotrusion side. Goods.

  According to (2), an intermediate holding layer is produced by segregation of light diffusing particles mixed in the shaping resin layer, or by laminating a light diffusing layer and a light transmitting layer of the same or different resins, and internal reflection It is possible to further reduce the reflection due to.

(3) In (1) or (2),
An antireflective article in which a substrate-side intermediate holding layer is further provided between the light diffusion layer and the substrate.

  According to (3), antireflection articles are constructed by applying various material layers capable of strengthening the adhesion between the base material and the shaping resin layer, and reflection by internal reflection has been conventionally achieved. Compared to this, it can be further reduced.

(4) In (1),
The intermediate holding layer is
It is a laminate of the substrate side intermediate holding layer and the microprojection side intermediate holding layer,
The antireflection article in which the light diffusion particles are mixed into the base-side intermediate holding layer and the light-diffusing layer is formed by the base-side intermediate holding layer.

  According to (4), when the base material side intermediate holding layer is configured by applying various material layers capable of strengthening the adhesion between the base material and the shaping resin layer, the base material side A light diffusing layer can be formed by mixing light diffusing particles into the intermediate holding layer.

  (5) An antireflection article in which the antireflection article according to any one of (1) to (4) is laminated and integrated with a linear polarizing plate.

  According to (5), the base material related to the fine protrusions can be shared with the base material related to the linearly polarizing plate to simplify the configuration.

  (6) An image display device in which the antireflection article according to any one of (1) to (4) is arranged on the panel surface of the image display panel.

  According to (6), in the image display device in which the antireflection article having the moth-eye structure is arranged, reflection due to internal reflection can be further reduced as compared with the conventional case.

  With respect to the antireflection article having the moth-eye structure, reflection due to internal reflection can be further reduced as compared with the conventional case.

1 is a conceptual perspective view showing an antireflection article according to a first embodiment of the present invention. It is a figure which shows the detail of the multimodal microprotrusion which concerns on the antireflection article | item of FIG. It is a photograph of multimodal microprotrusions. It is a figure where it uses for description of an adjacent protrusion. It is a figure where it uses for description of the maximum point. It is a figure which shows a Delaunay figure. It is a frequency distribution diagram used for measurement of the distance between adjacent protrusions. It is a frequency distribution diagram used for description of the height of the minute protrusions. It is a frequency distribution diagram used for description of the distribution of the height of the microprojections. It is a graph which shows the measurement result of distribution of the height of a microprotrusion. It is a figure which shows the manufacturing process of the antireflection article | item of FIG. It is a figure which shows the roll plate which concerns on the reflection preventing article of FIG. It is a figure which shows the preparation processes of the roll plate of FIG. It is a figure where it uses for detailed description of an anodizing process and an etching process. It is a conceptual perspective view which shows the reflection preventing article which concerns on 2nd Embodiment of this invention. It is a figure which shows the measurement result of an Example. It is a figure which shows the example in case an envelope surface exhibits a wave | undulation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, a microprotrusion having a plurality of vertices will be referred to as a multimodal microprotrusion, and a microprotrusion having only one apex will be referred to as a unimodal microprotrusion. Further, in the following, when simply referred to as a microprojection, both a single-peak microprojection and a multimodal microprojection are included.

[First Embodiment]
FIG. 1 is a diagram (conceptual perspective view) showing an image display apparatus according to a first embodiment of the present invention. The image display device 100 is a liquid crystal display device, and a backlight device 101 and a liquid crystal display panel 102 are sequentially arranged. Here, the backlight device 101 can widely apply various configurations such as an edge light type and a direct-light type. The liquid crystal display panel 102 is configured by sandwiching a liquid crystal cell 103 between linearly polarizing plates 104 and 105. The liquid crystal cell 103 is formed by sandwiching a liquid crystal layer 110 made of a liquid crystal material between glass substrates 111 and 112 on which transparent electrodes are formed. In the image display device 100, the antireflection film 1 that is a film-like antireflection article is disposed on the emission surface of the liquid crystal display panel 102.

  Here, the linearly polarizing plates 104 and 105 sandwich an optical functional layer (a so-called polarizer) 106 that functions as a linearly polarizing plate by the base materials 107 and 108 that are transparent film materials that function as protective layers, respectively. It is formed. In this embodiment, of the linearly polarizing plates 104 and 105, the outgoing surface side linear polarizing plate 105 is configured such that the outgoing surface side base material 108 also serves as the base material 2 of the antireflection film 1. Thus, the antireflection film 1 is manufactured integrally with the linearly polarizing plate, thereby simplifying the overall configuration and reducing the overall thickness. The antireflection film 1 may be prepared separately from the linear polarizing plate.

  Here, the antireflection film 1 is produced by closely arranging a large number of minute protrusions 5, 5 </ b> A, and 5 </ b> B on the surface of the substrate 2 in the shape (form) of a transparent film. Here, the base material 2 is, for example, a cellulose resin such as TAC (Triacetylcellulose), an acrylic resin such as PMMA (polymethyl methacrylate), a polyester resin such as PET (Polyethylene terephthalate), or PP (polypropylene). Polyolefin resins such as PVC, vinyl resins such as PVC (polyvinyl chloride), and various transparent resin films such as PC (polycarbonate) can be applied. When the antireflection film 1 is used for an image display device, TAC or acrylic is preferably used for the base material 2.

  The antireflection film 1 is an uncured resin layer (a so-called shaping resin layer, which is also referred to as a receiving layer as appropriate) 4 on the base material 2 to be a fine uneven receiving layer composed of a group of minute protrusions. Then, the receiving layer 4 is subjected to a molding treatment and hardened, whereby the fine protrusions are placed in close contact with the surface of the substrate 2. In this embodiment, an acrylate ultraviolet curable resin, which is one of the molding resins used for the molding process, is applied to the receptor layer 4, and the receptor layer 4 is formed on the substrate 2 by the ultraviolet curable resin layer. It is formed. The antireflection film 1 is produced so that the refractive index gradually changes in the thickness direction due to the uneven shape by the fine protrusions, and reduces reflection of incident light in a wide wavelength range by the principle of the moth-eye structure. Further, as a result, the antireflection film 1 is formed with a microprojection layer 5X formed by closely arranging the microprojections 5, and an intermediate holding layer that holds the microprojection layer 5X on the substrate 2 is shaped by the receiving layer 4. It will be constituted by the resin layer for use.

  In addition, the antireflection film 1 is formed on the substrate 2 side of the intermediate holding layer, if necessary, an underlayer (base material side intermediate holding layer) that reinforces the adhesion of the receiving layer 4 that is the intermediate holding layer. Is done. As such an intermediate holding layer, various material layers capable of strengthening the adhesion between the base material 2 and the resin material related to the receiving layer 4 can be widely applied. For example, an ultraviolet curable resin or a thermosetting resin can be used. Applied. When an ultraviolet curable resin is used, a half-cure treatment is often applied. Here, if the refractive index difference between the substrate side intermediate holding layer and the microprojection side intermediate holding layer is large, the interlayer reflection between the substrate side intermediate holding layer and the microprojection side intermediate holding layer becomes large. A small value is preferable, and the difference in refractive index is preferably smaller than 0.03. Further, when a transparent film material such as a PET film is applied to the base material 2, an adhesive force is further strengthened on the base material side of the base material side intermediate support layer by providing a base material side intermediate support layer. In addition, an easy adhesion layer having a refractive index adjusted so as to reduce interface reflection is provided.

  Further, in this embodiment, the light diffusing particles 8 are mixed in the ultraviolet curable resin used for producing the receiving layer 4. Here, the light diffusing particles 8 are produced in the antireflection article with a size that is sufficiently larger than the shortest wavelength to be used for antireflection and capable of scattering the transmitted light. Each stage has a larger size. More specifically, the light diffusing particles have a particle size of 2 μm or more and 10 μm or less.

  Further, in this embodiment, as shown in a partially enlarged manner by reference numeral A, in the intermediate holding layer by the receiving layer 4, the light diffusing particles 8 are segregated to the substrate 2 side, that is, the substrate 2 side. Then, the inter-particle distance of the light diffusing particles is relatively short, and the inter-particle distance is gradually increased as the distance from the substrate 2 is increased, and the inter-particle distance is relatively increased on the microprotrusion 5 side. Thereby, in this embodiment, in this intermediate | middle holding layer, the light-diffusion layer 4B provided with the light-diffusion particle is produced in the side close | similar to the base material 2. FIG. Further, the intermediate holding layer is constituted by the shaping resin layer provided for the shaping treatment of the microprojections provided with the light diffusing particles 8, and the light diffusing particles 8 are formed on the substrate 2 side in the shaping resin layer. The light diffusing layer 4B is formed by relatively shortening the inter-particle distance, and the inter-particle distance of the light diffusing particles is relatively increased on the microprojection 5 side to suppress the scattering of transmitted light. Is formed. In this embodiment, by producing the light diffusion layer 4B and the light transmission layer 4A by segregation of the light diffusion particles 8 in this way, the distance between the particles gradually increases as the distance from the substrate 2 increases. 4B and the light transmission layer 4A are configured so that the boundary between them cannot be clearly grasped, but as indicated by the symbol B, it is configured so that the boundary between the light diffusion layer 4B and the light transmission layer 4A can be clearly understood. May be. In addition, when comprised in this way, after coating the coating liquid which concerns on the light-diffusion layer 4B, it is in the light transmissive layer 4A in which the light-diffusion particle | grains by the same or different resin material as the light-diffusion layer 4B are not mixed. After coating the coating liquid, or after coating and curing the coating liquid related to the light diffusion layer 4B, light diffusion particles made of the same or different resin material as the light diffusion layer 4B are mixed. By applying the coating liquid related to the light transmissive layer 4A that is not present, the light diffusing layer B and the light transmissive layer 4A can be laminated.

  When the light diffusing layer 4B is provided in this way, the light diffusing layer 4B can scatter the internal reflected light on the side closer to the source of the internal reflected light, thereby efficiently scattering the internal reflected light. Reflection due to internal reflection can be reduced. In addition, since the reflection of light is reduced by the light diffusion layer and the moth-eye structure is formed on the surface, even if the internal reflection light is sufficiently scattered by the light diffusion layer, the resulting scattered light Reflection and scattering at the outermost surface can be reduced. Thereby, a large amount of light diffusing particles in the light diffusing layer can be mixed to effectively reduce the reflection due to internal reflection, and the whiteness of the display screen due to the haze value deterioration can be effectively avoided.

  More specifically, according to the result of the experiment, a film material provided with a light diffusion layer having a haze value of 38%, 42%, and 59% is applied to the base material 2 to produce a microprojection to produce an antireflection film. When fabricated, the haze values were 20%, 25%, and 30%, respectively, and it was confirmed that the haze value was remarkably reduced by providing the minute protrusions 5. Such a decrease in haze value is caused by the fact that the diffused light diffused by the light diffusing layer is reflected or diffused on the surface of the film material when no microprotrusions are provided. Compared with the haze value, the haze value actually measured as a film material is increased, but when a minute protrusion is arranged, the reflection and diffusion on the surface are reduced, thereby reducing the internal haze value. It is considered that a haze value with a value approximately equal to is measured by the film material. As a result, reflections due to internal reflection can be efficiently reduced, and furthermore, the phenomenon such as whiteness of the display screen due to prevention of reflection due to diffusion of the internal reflection light can be sufficiently suppressed in practice. it can. In the experiment using these film materials, the front reflectance by arranging the minute protrusions is 0.18%, and even if the internal reflected light is scattered, the reflectance is sufficiently reduced by the moth-eye structure. It was confirmed that it was possible. When the internally reflected light is diffused in this way, it is possible to sufficiently suppress the display screen glare that occurs when a film material having a moth-eye structure is arranged on the panel surface of the image display panel.

  Here, in order to ensure the effect of reducing the reflection due to such internal reflection, it is necessary to sufficiently scatter the internal reflection light. However, if the degree of scattering is too large, the display screen becomes white. By being observed, the visibility deteriorates on the contrary. Therefore, the light diffusion particles 8 are added to the light diffusion layer 4B in a weight ratio of 20% to 50%. Even if the addition amount is set in this way, if the light diffusion layer 4B is thin, the transmitted light cannot be sufficiently diffused, and reflection occurs, whereas the thickness of the light diffusion layer 4B is When it is thick, the transmitted light is too diffused. Accordingly, in this embodiment, the intermediate holding layer 4 is configured with a thickness of 5 μm or more and 50 μm or less. In the configuration indicated by the symbol B, the light diffusion layer 4B is configured with a thickness of 5 μm or more and 50 μm or less. For light diffusing particles, various materials such as acrylic and styrene resin materials having different refractive indices with respect to the resin material constituting the receiving layer, and white materials typified by silica are widely used. be able to.

  By producing the light diffusion layer 4B in this manner, the antireflection film 1 is produced with a haze value of 10 or more and 50 or less without providing the optical functional layer 106 and the base material 108 related to the linearly polarizing plate. The The haze value is preferably 20 or more and 40 or less. When the haze value is low, the effect of blurring reflection of internal reflection is weak, and when the haze value is high, whitishness becomes conspicuous.

[Shape of microprojection]
The antireflection film 1 is set so that monomodal microprotrusions and multimodal microprotrusions 5A, 5B are mixed. Here, the multimodal microprotrusions 5A and 5B are microprotrusions having a plurality of apexes, and the single-peak microprotrusions are microprotrusions having only one apex. Thereby, in this embodiment, the scratch resistance of the antireflection article is improved.

  That is, FIG. 2 is a diagram for explaining the multimodal microprotrusions 5A and 5B and the single-peak microprotrusions. Note that FIG. 2 is a diagram schematically showing for easy understanding, and FIG. 2A is a diagram showing a cross section by a broken line connecting the vertices of continuous minute protrusions. 2 (b) and 2 (c), the xy direction is the in-plane direction of the substrate 2, and the z direction is the height direction of the microprojections.

  In the antireflection film 1, many microprotrusions 5 are gradually cut in a cross-sectional area (a plane perpendicular to the height direction (a plane parallel to the XY plane in FIG. 2)) toward the apex away from the substrate 2. The cross-sectional area) is reduced, and one vertex is produced. However, in some cases, as if a plurality of microprotrusions were combined, a groove g was formed at the tip, and the apex was two (5A), the apex was three (5B), Furthermore, there can be one having four or more vertices (not shown). The shape of the unimodal microprotrusions 5 can be approximated by a round shape at the top, such as a paraboloid of revolution, or a sharp shape at the apex, such as a cone. On the other hand, the shape of the multimodal microprotrusions 5A and 5B is approximately approximated by a shape in which a groove-shaped recess is cut in the vicinity of the top of the single-peak microprotrusion 5 and the top is divided into a plurality of peaks.

  The multimodal microprotrusions having a plurality of vertices are relatively thicker at the hem than the unimodal microprotrusions, compared to the multimodal microprotrusions. Long perimeter. Thereby, it can be said that the multimodal microprotrusions are superior in mechanical strength to the single-peak microprotrusions. As a result, when multi-peaked microprojections having a plurality of vertices are present, the anti-reflective article has improved scratch resistance compared to the case of using only single-peaked microprojections. Specifically, when external force is applied to the anti-reflective article, the external force is distributed and received at more vertices than when only single-peaked microprotrusions are received. Can be made difficult to damage, thereby reducing local deterioration of the antireflection function and further reducing the occurrence of poor appearance. Moreover, even if a microprotrusion is damaged, the area of the damaged portion can be reduced. In addition, the multi-peak microprojections are higher than the multi-peak micro-projections and lower body parts than the multi-peak micro-projections by first receiving each external force and sacrificing damage. It is possible to prevent wear of small protrusions. This also reduces local deterioration of the antireflection function and further reduces the occurrence of appearance defects.

  Needless to say, although the multimodal microprotrusions can improve the scratch resistance due to their presence, if they do not exist sufficiently, the effect of improving the scratch resistance cannot be fully exhibited. From such a viewpoint, it is desirable that the ratio of the number of multimodal microprotrusions in all the microprotrusions existing on the surface be 10% or more. In particular, in order to sufficiently exhibit the effect of improving the scratch resistance by the multimodal microprotrusions, the ratio of the multimodal microprotrusions is desired to be 30% or more, preferably 50% or more. Further, since the difficulty of managing the manufacturing process increases as the ratio of the multimodal microprotrusions increases, the ratio is preferably 90% or less, more preferably 80% or less. In addition, by setting the existence ratio of the single-peaked microprotrusions in this manner, sticking can be made difficult to occur, and as a result, deterioration of characteristics due to sticking can be effectively avoided. Furthermore, when unimodal microprojections are mixed with multimodal microprojections, the reflectance can be reduced over a wide wavelength band, as with unimodal microprojections with different aspect ratios. it can.

  The aspect ratio is defined as H / W, which is a ratio obtained by dividing the height H of the minute protrusions by the diameter W (also referred to as width or thickness) at the bottom of the valley. Here, the diameter at the bottom of the valley coincides with the diameter (at the bottom) of the column if the shape of the microprotrusion near the bottom of the valley is a column. If the shape of the vicinity of the valley bottom of the microprojection is not a cylinder and the diameter of the bottom surface obtained by crossing the virtual plane connecting the valley bottom and the microprojection differs depending on the in-plane direction, the maximum value is set to the microprojection. Of the diameter. For example, when the bottom shape of the microprojection is an ellipse, the diameter is the major axis. In addition, when the bottom surface shape of the minute protrusion is a polygon, the diameter is the maximum diagonal length. In addition, when the width of the bottom of the valley (region consisting of the minimum point of the height) is smaller than the diameter and 20% or less, the average value (H / W) ave of the aspect ratio H / W of each microprotrusion is In terms of design, it can be substantially regarded as Have / dave.

  FIG. 3 is a photograph showing a plurality of minute protrusions at the apex, FIG. 3 (a) is based on AFM, and FIGS. 3 (b) and 3 (c) are based on SEM. In FIG. 3 (a), a groove g and a microprotrusion having three vertices and a microprotrusion having a groove g and two vertices (two-peaked multimodal microprotrusions) can be seen. In FIG. 3 (c), the groove g and the microprotrusions having four vertices (four-peaked multimodal microprotrusions) and the groove g and the microprotrusions having two vertices can be seen. One can see microprojections with three vertices (three-peak multimodal microprojections), groove g and microprojections with two vertices.

[Distance between adjacent protrusions]
The minute protrusions produced on the antireflection film 1 are closely arranged so that the distance d between adjacent minute protrusions is equal to or less than the shortest wavelength Λmin (d ≦ Λmin) of the wavelength band of the electromagnetic wave for preventing reflection. In this embodiment, since the main purpose is to improve visibility by arranging the image display panel, the shortest wavelength is set to the shortest wavelength (380 nm) in the visible light region in consideration of individual differences and viewing conditions. The distance d is set to 100 to 300 nm in consideration of variation. The adjacent minute protrusions related to the distance d are so-called adjacent minute protrusions, which are in contact with the hem portions of the minute protrusions, which are the base portions on the base 2 side. In the antireflection film 1, the minute protrusions are closely arranged so that when a line segment is formed so as to sequentially follow the valley portions between the minute protrusions, a large number of polygonal regions surrounding each minute protrusion are connected in plan view. Thus, a mesh-like pattern is produced. The adjacent minute protrusions related to the distance d are protrusions that share a part of the line segments constituting the mesh pattern.

  The minute protrusions are defined in more detail as follows. In the antireflection by the moth-eye structure, the effective refractive index at the interface between the transparent substrate surface and the adjacent medium is continuously changed in the thickness direction to prevent reflection. It is necessary to satisfy the following conditions. With respect to the protrusion interval, which is one of these conditions, when the minute protrusions are regularly arranged at a constant period as disclosed in, for example, Japanese Patent Application Laid-Open No. 50-70040 and Japanese Patent No. 4632589, the adjacent spaces are adjacent to each other. The interval d between the minute projections to be performed is the projection arrangement period P (d = P). Thus, when the longest wavelength in the visible light band is λmax and the shortest wavelength is λmin, the minimum necessary condition that can exhibit the antireflection effect at the longest wavelength in the visible light band is Λmin = λmax. P ≦ λmax, and the necessary and sufficient condition that can exhibit the antireflection effect for all wavelengths in the visible light band is Λmin = λmin, and therefore P ≦ λmin.

  The wavelengths λmax and λmin may have some width depending on observation conditions, light intensity (luminance), individual differences, and the like, but are typically λmax = 780 nm and λmin = 380 nm. A preferable condition that can more reliably exhibit the antireflection effect for all wavelengths in the visible light band is d ≦ 300 nm, and a more preferable condition is an oblique direction (at least 45 degrees with respect to the normal of the surface of the substrate 2). D ≦ 200 nm from the viewpoint of reducing the cloudiness when viewed from an angle direction. Note that the lower limit value of the period d is usually d ≧ 50 nm, preferably d ≧ 100 nm, for reasons such as the expression of the antireflection effect and the securing of the isotropic (low angle dependency) of the reflectance. On the other hand, the height H of the protrusion is set to H ≧ 0.2 × λmax = 156 nm (assuming λmax = 780 nm) from the viewpoint of exhibiting a sufficient antireflection effect.

  However, when the minute protrusions are irregularly arranged as in this embodiment, the distance d between the adjacent minute protrusions varies. More specifically, as shown in FIG. 4, when the microprojections are not regularly arranged at a constant period when viewed from the normal direction of the front or back surface of the substrate, the repetition period P of the protrusions In some cases, the distance d between adjacent protrusions cannot be defined, and even the concept of adjacent protrusions is suspicious. Therefore, in such a case, it is calculated as follows.

  (1) That is, first, an in-plane arrangement (projection arrangement) of projections using an atomic force microscope (Atomic Force Microscope (hereinafter referred to as AFM)) or a scanning electron microscope (hereinafter referred to as SEM). ) Is detected. FIG. 4 is an enlarged photograph actually obtained by an atomic force microscope. Since the AFM data is accompanied by the in-plane distribution data of the height of the microprojections, this photo can be said to be a photo showing the in-plane distribution of height by luminance.

  (2) Subsequently, the maximum point of the height of each protrusion (hereinafter simply referred to as the maximum point) is detected from the obtained in-plane arrangement. Here, the maximum point means a point where the height is maximum (maximum value) compared to any point in the vicinity thereof. As a method for obtaining the maximum point, (a) a method for obtaining the maximum point by sequentially comparing the plane coordinates on the enlarged photograph of the planar view shape and the height data obtained from the corresponding cross-sectional shape, (b) Various methods such as a method of obtaining a local maximum point by image processing of a planar view enlarged photograph obtained by converting the height distribution data in the plane coordinates on the base material obtained by AFM into a two-dimensional image can be applied. 4 is an enlarged photograph (corresponding to the image density is high) by AFM, and FIG. 5 is a diagram showing a detection result of the maximum point by processing of image data related to the enlarged photograph shown in FIG. In the figure, each point indicated by a black dot is the maximum point of each protrusion. In this process, image data is processed in advance by a low-pass filter having a Gaussian characteristic of 4.5 × 4.5 pixels, thereby preventing erroneous detection of the maximum point due to noise. Further, a maximum point was obtained in units of 1 nm (= 1 pixel) by sequentially scanning a filter for detecting a maximum value of 8 pixels × 8 pixels.

  (3) Next, a Delaunay diagram (Delaunary Diagram) having the detected maximum point as a generating point is created. Here, Delaunay diagram is obtained by dividing the Voronoi region adjacent to the Voronoi region when the Voronoi division is performed with each local maximum as the generating point, and connecting the adjacent generating points with line segments. This is a net-like figure made up of triangular aggregates. Each triangle is called a Delaunay triangle, and a side of each triangle (a line segment connecting adjacent generating points) is called a Delaunay line. FIG. 6 is a diagram in which the Delaunay diagram (represented by white line segments) obtained from FIG. 5 is superimposed on the original image of FIG. The Delaunay diagram has a dual relationship with the Voronoi diagram. Voronoi division means that a plane is divided by a net-like figure made up of a closed polygon aggregate defined by perpendicular bisectors of line segments (Droney lines) connecting between adjacent generating points. A network figure obtained by Voronoi division is a Voronoi diagram, and each closed region is a Voronoi region.

  (4) Next, the frequency distribution of the line segment length of each Delaunay line, that is, the frequency distribution of the distance between adjacent maximum points (hereinafter referred to as the distance between adjacent protrusions) is obtained. FIG. 7 is a histogram of the frequency distribution created from the Delaunay diagram of FIG. In addition, as shown by reference numerals 5A and 5B in FIG. 4, when a concave portion such as a groove exists at the top of the protrusion, or when the top is divided into a plurality of peaks, from the obtained frequency distribution, A frequency distribution is created by removing data resulting from a fine structure having a concave portion at the top of the protrusion and a fine structure in which the top is split into a plurality of peaks, and selecting only the data of the protrusion main body itself.

  Specifically, in the fine structure in which there is a concave portion on the top of the protrusion, or in the fine structure related to a multi-peak microprotrusion in which the top is divided into a plurality of peaks, the single peak property that does not have such a fine structure From the numerical range in the case of a microprotrusion, the distance between adjacent maximum points is clearly greatly different. Thus, by removing the corresponding data using this feature, only the data of the projection body itself is selected and the frequency distribution is detected. More specifically, for example, about 5 to 20 adjacent single-peak microprojections are selected from an enlarged photograph of the microprojections (group) as shown in FIG. A value that deviates in a direction that is clearly smaller than the numerical range obtained by sampling this value (usually the value is ½ or less of the average distance between adjacent maximum points obtained by sampling) Frequency distribution is detected. In the example of FIG. 7, data having a distance between adjacent maximal points of 56 nm or less (the leftmost small mountain indicated by the arrow A) is excluded. FIG. 5 shows a frequency distribution before performing such exclusion processing. Incidentally, such exclusion processing may be executed by setting the above-described maximum inspection filter.

(5) The average value d _AVG and the standard deviation σ are obtained from the frequency distribution of the distance d between adjacent protrusions thus obtained. Here, when the frequency distribution obtained in this way is regarded as a normal distribution and the average value d _AVG and the standard deviation σ are obtained, the average value d _AVG = 158 nm and the standard deviation σ = 38 nm are obtained in the example of FIG. As a result, the maximum value of the distance d between adjacent protrusions is set to dmax = d _AVG + 2σ, and in this example, dmax = 234 nm.

The same method is applied to define the height of the protrusion. In this case, a relative height difference of each local maximum point position from a specific reference position is acquired from the local maximum point obtained by the above (2), and is histogrammed. FIG. 8 is a diagram showing a histogram of the frequency distribution of the protrusion height H with the protrusion root position obtained in this way as a reference (height 0). The average value _HAVG of the protrusion height and the standard deviation σ are obtained from the frequency distribution based on the histogram. Here in the example of FIG. 8, the mean value _H AVG = 178 nm, the standard deviation sigma = 30 nm. Thus in this example, the height of the projections is an average value _H AVG = 178 nm. In the histogram of the protrusion height H shown in FIG. 8, in the case of a multi-peak microprotrusion, the plurality of data is mixed for one protrusion because of having a plurality of vertices. Therefore, in this case, the frequency distribution is obtained by adopting the vertex having the highest height from among the plurality of vertices belonging to the same microprotrusion as the protuberance. Moreover, when all the peaks which share a collar part are the same height, let it be the height of this microprotrusion with the same height.

  In addition, the reference position when measuring the height of the protrusion described above is based on the valley bottom (minimum point of height) between the adjacent minute protrusions as a reference of height 0. However, as will be described later, for example, when the height of the valley bottom has ridges with a period larger than the distance between adjacent projections of the microprojections, if the height of the valley bottom itself varies depending on the location, (1) The average value of the height of each valley bottom measured from the front surface or the back surface of the base material 2 is calculated within an area sufficient for the average value to be collected. (2) Next, a surface having the height of the average value and parallel to the front surface or the back surface of the substrate 2 is considered as a reference surface. (3) Then, the height of each microprotrusion from the reference surface is calculated by setting the reference surface to a height of 0 again.

If the protrusions are irregularly arranged, when this way the maximum value of the adjacent protrusions distance obtained by dmax = d AVG ₊ 2σ, average H _AVG height of projections are arranged regularly It has been found necessary to satisfy the above conditions. Specifically, the condition of the distance between the microprotrusions that exhibits the antireflection effect is dmax ≦ Λmin. The minimum necessary condition that can exhibit the antireflection effect at the longest wavelength in the visible light band is Λmin = λmax, and therefore dmax ≦ λmax, and the antireflection effect can be achieved for all wavelengths in the visible light band. The necessary and sufficient condition is Λmin = λmin, and therefore dmax ≦ λmin. A preferable condition that can more reliably exhibit the antireflection effect for all wavelengths in the visible light band is dmax ≦ 300 nm, and a more preferable condition is dmax ≦ 200 nm. Also, dmax ≧ 50 nm is usually satisfied and dmax ≧ 100 nm is preferable because of the antireflection effect and ensuring the isotropic (low angle dependency) of the reflectance. The height of the protrusion is set to _HAVG ≧ 0.2 × λmax = 156 nm (assuming λmax = 780 nm) in order to exhibit a sufficient antireflection effect. However, from the viewpoint of ensuring the antireflection function to a practically sufficient level, the average inter-protrusion distance dave may be set so that dave ≦ λmin.

4 to 8, dmax = 234 nm ≦ λmax = 780 nm, and it can be seen that the antireflection effect can be sufficiently achieved by satisfying the condition of dmax ≦ λmax. In addition, since the shortest wavelength λmin in the visible light band is 380 nm, it can be seen that the sufficient condition dmax ≦ λmin for exhibiting the antireflection effect in all visible light wavelength bands is also satisfied. Since dave ≦ dmax, it can be seen that the condition of dave ≦ λmin is also satisfied. When the average protrusion the height _H AVG = 178 nm Also, the average projection height _{H AVG} ≧ 0.2 × λmax = _156nm becomes (as the longest wavelength .lambda.max = 780 nm in the visible light wavelength band), realizing a sufficient antireflection effect It can be seen that the conditions regarding the height of the protrusions to satisfy are also satisfied. Note since the standard deviation sigma = 30 _nm, since the relationship between the _{H AVG -σ = 148nm <0.2 ×} λmax = 156nm is satisfied, statistically, more than 50% of the total protrusions, 84% or less It can be seen that the condition of the height of the protrusion (178 nm or more) is satisfied. In addition, from the observation result by AFM and SEM and the analysis result of the height distribution of the microprojections, the multi-peak microprojections tend to be generated more frequently in the microprojections having a higher height than the microprojections having a relatively low height. It has been found.

  Note that the measurement results in FIGS. 7 and 8 described above are measurement results for explaining the distance between adjacent protrusions, and are different from the measurement results according to this embodiment.

[Height distribution]
Here, the multi-peak microprotrusions formed on the antireflection article need to be formed so as to satisfy the following conditions in order to improve the antireflection function for the incident light in the visible light region described above. There is.

FIG. 9 is a diagram illustrating an example of the frequency distribution of the height h of the fine protrusions formed on the antireflection article. As shown in FIG. 9, the average value of the heights in the frequency distribution of the height h of the microprojections is m, the standard deviation is σ, the region of h <m−σ is the low altitude region of the microprojections, and m− When the region of σ ≦ h ≦ m + σ is a medium altitude region and the region of m + σ <h is a high altitude region, the number Nm of multimodal microprojections in each region and the total number of microprojections in the entire frequency distribution It is fabricated so that the ratio to Nt satisfies the following relationships (a) and (b).
(A) Nm / Nt in the middle altitude region> Nm / Nt in the low altitude region
(B) Nm / Nt in middle altitude region> Nm / Nt in high altitude region

  FIG. 10 is a diagram showing the measurement results of the height of the antireflection article according to this embodiment. In FIG. 13, the average value of the heights of the microprojections is m = 145.7 nm, and the standard deviation is σ = 22.1 nm. Here, in the frequency distribution of the height h of the microprotrusions, the low altitude region is h <m−σ = 123.6 nm, and the middle altitude region is m−σ = 13.6 nm ≦ h ≦ m + σ = 167.8 nm. Thus, the high altitude region is h> m + σ = 167.8 nm.

  The total number Nt of microprojections in the entire frequency distribution is 263. Further, since the number Nm of multi-modal microprotrusions in the middle altitude region is 23, Nm / Nt in the middle altitude region is 0.087. Since the number Nm of multimodal microprotrusions in the low altitude region is two, Nm / Nt in the low altitude region is 0.008. Since the number Nm of multi-modal microprotrusions in the high altitude region is 5, Nm / Nt in the high altitude region is 0.019.

Therefore, the antireflection article of the present example has the above-described relationships (a) and (b), that is,
(A) Nm / Nt in the middle altitude region = 0.087> Nm / Nt = 0.008 in the low altitude region
(B) Nm / Nt = 0.087 in the medium altitude region> Nm / Nt = 0.19 in the high altitude region
Satisfied.

  Thus, the ratio (Nm / Nt) of the number of multi-protrusion microprojections (Nm) in the medium altitude region to the total number of microprojections (Nt) in the frequency distribution is higher than the ratio of the low altitude region and the high altitude region. By forming multi-peak microprojections so as to be large, the reflectance with respect to incident light in the visible light region can be reduced, and the antireflection article can have a broad antireflection function.

  In addition, this anti-reflective article has an average value of almost the same height for multi-peak microprojections (two and three vertices are indicated by two peaks and three peaks, respectively) in such a height distribution. Therefore, the viewing angle characteristic is limited and rainbow unevenness due to optical interference is suppressed, and a screen that is low in reflection and visually favorable for the viewer can be created. In addition, the scratch resistance of the multimodal microprotrusions can be improved efficiently.

  Further, by adopting the above-described configuration, the anti-reflection article has a small ratio of multi-peak microprojections distributed in microprojections having a high height (180 nm or more), and a large ratio of single-peak microprojections. Even if other objects come into frictional contact with the microprojections, the high unimodal microprotrusions come into contact first, and contact with the multimodal microprojections that mainly improve the antireflection function. Can be suppressed.

  Note that the characteristics of these multimodal microprotrusions are unique characteristics of the multimodal microprotrusions produced by the microholes having the corresponding shapes of the shaping mold, and Japanese Patent Application Laid-Open No. 2012-037670. This is a feature that cannot be obtained by the multi-modal microprotrusions caused by the resin filling failure disclosed in the publication. That is, the multi-peak microprotrusions due to poor filling of the resin are produced by not sufficiently filling the fine holes that are originally produced as single-peak microprotrusions, so that there is a gap between the vertices. Therefore, it is difficult to sufficiently improve the scratch resistance, and it is also difficult to improve the optical characteristics as described above.

  In addition, in the multi-peak microprojections due to poor filling, there is a disadvantage that the reproducibility is poor, and thus a uniform product cannot be mass-produced, whereas the multi-peak micro-projections according to this embodiment are High reproducibility can be ensured by a so-called mold. In addition, as described in detail for the above-described embodiments, the height distribution of multimodal microprojections can be controlled, whereas such control is difficult for poorly filled multimodal microprojections. .

〔Manufacturing process〕
FIG. 11 is a diagram showing a manufacturing process of the antireflection film 1. In the manufacturing process 10, in the resin supply process, an uncured and liquid acrylate ultraviolet curable resin that forms the receiving layer 4 is applied to the base material 2 in the form of a strip film by the die 11. In addition, about application | coating of these coating liquids, not only the case by the die | dye 11 but various methods are applicable. Subsequently, in the manufacturing process 10, the coating liquid related to the receiving layer 4 is subjected to a leveling process and a drying process. In this embodiment, in this leveling process, the side on which the coating liquid is applied is the upper side of the substrate 2 so that the light diffusing particles 8 are segregated by gravity to form the light diffusing layer 4B and the light transmitting layer 4A. The process is set such that the amount of the solvent related to the coating liquid and the time of the leveling process are set. Subsequently, in this step, the pressing roller 14 presses and presses the base material 2 against the peripheral side surface of the roll plate 13 which is a mold for shaping the antireflection article, whereby the base material 2 is liquid in an uncured state. The UV curable resin is brought into close contact, and the UV curable resin is sufficiently filled in the concave portions having fine irregularities formed on the peripheral side surface of the roll plate 13. In this state, in this manufacturing process, the ultraviolet curable resin is cured by irradiation with ultraviolet rays, and thereby a microprojection group is produced on the surface of the substrate 2. In this manufacturing process, the substrate 2 is peeled off from the roll plate 13 through the peeling roller 15 together with the cured ultraviolet curable resin. In the manufacturing process 10, an adhesive layer or the like is formed on the substrate 2 as necessary, and then cut into a desired size to produce the antireflection film 1. Thereby, the antireflection film 1 is mass-produced efficiently by sequentially molding the fine shape produced on the peripheral side surface of the roll plate 13 which is a mold for molding on the long base material 2 made of a roll material. The In addition, as shown with the code | symbol B in FIG. 1, when producing the light-diffusion layer 4B and the light transmissive layer 4A by lamination | stacking, the process of apply | coating a coating liquid is provided, respectively, and the hardening process is added as needed. Is done. Further, when the base-side intermediate holding layer is disposed, a step of applying the coating liquid according to the base-side intermediate holding layer and drying or curing it is provided before the coating liquid is applied by the die 11. It is done. Moreover, when providing an easily bonding layer, the process of producing an easily bonding layer in the base material 2 in advance is provided.

  After producing the microprotrusions 5 on one surface of the substrate 2 in this way, the manufacturing process includes a step of saponifying the other surface of the substrate 2, and then sequentially providing the optical functional layer 106 and the substrate 107, As a result, the substrate 2 is also used and integrated with the linear polarizing plate.

[Roll plate making process]
FIG. 12 is a perspective view showing the configuration of the roll plate 13. In the roll plate 13, a fine concavo-convex shape is produced on the peripheral side surface of the base material, which is a cylindrical metal material, by repetition of anodizing treatment and etching treatment, and this fine concavo-convex shape is formed on the substrate 2. The For this reason, as for the roll plate 13, a columnar or cylindrical member in which a high purity aluminum layer is provided at least on the peripheral side surface is applied to the base material. More specifically, in this embodiment, a hollow stainless steel pipe is applied to the base material, and a high-purity aluminum layer has a curved shape corresponding to the envelope surface 9 of the valley bottom, either directly or through various intermediate layers. Provided. In addition, it may replace with a stainless steel pipe and may apply pipe materials, such as copper and aluminum. In the roll plate 13, fine holes are densely formed on the peripheral side surface of the base material by repeating the anodizing treatment and the etching treatment, and the fine holes are dug, and the diameter of the roll plate 13 increases as it approaches the opening. The concavo-convex shape is produced by gradually increasing the diameter of the fine holes. As a result, the roll plate 13 is closely formed with fine holes whose diameter gradually decreases in the depth direction, and the diameter of the antireflection film 1 gradually decreases as it approaches the top corresponding to the fine holes. A fine concavo-convex shape is produced by a large number of fine protrusions.

  FIG. 13 is a diagram showing a manufacturing process of the roll plate 13. In this manufacturing process, the peripheral side surface of the base material is made into a super mirror surface by an electrolytic composite polishing method that combines electrolytic elution action and abrasion action by abrasive grains (electrolytic polishing).

  In the aluminum layer forming step, aluminum is sputtered on the peripheral side surface of the base material to produce a high purity aluminum layer. Subsequently, in this process, the base material is processed by alternately repeating the anodic oxidation processes A1,..., AN, and the etching processes E1,.

  More specifically, in this manufacturing process, in the anodic oxidation process A1,..., AN, a fine hole is produced on the peripheral side surface of the base material by an anodic oxidation method, and the produced fine hole is further dug. Here, in the anodic oxidation step, various methods applied to the anodic oxidation of aluminum can be widely applied, for example, when a carbon rod, a stainless steel plate, or the like is used for the negative electrode. Further, as the solution, various neutral and acidic solutions can be used, and more specifically, for example, sulfuric acid aqueous solution, oxalic acid aqueous solution, phosphoric acid aqueous solution and the like can be used. In the manufacturing steps A1,..., AN, the fine holes are formed in shapes corresponding to the target depth and the shape of the fine protrusions, respectively, by managing the liquid temperature, the applied voltage, the time for anodization, and the like.

  In the subsequent etching step E1,..., EN, the base material is immersed in an etching solution, the hole diameter of the fine hole produced and dug in the anodizing step A1,. These fine holes are shaped so that the hole diameter becomes smaller and smoother. As the etching solution, various etching solutions that are applied to this type of treatment can be widely applied. More specifically, for example, a sulfuric acid aqueous solution, an oxalic acid aqueous solution, a phosphoric acid aqueous solution, or the like can be used. As a result, in this manufacturing process, the anodizing process and the etching process are alternately performed a plurality of times, so that fine holes for forming are formed on the peripheral side surface of the base material. The anodizing solution itself such as an oxalic acid aqueous solution used in the anodizing treatment functions as an etching solution if it is brought into contact with the base material without applying a voltage. Therefore, the anodizing treatment solution and the etching solution are the same solution, and the anodizing treatment is performed by sequentially applying a predetermined voltage for a predetermined time while the base material is immersed in a bath containing the same solution, and no voltage is applied. Etching can also be performed by immersing in a predetermined time.

[Details of anodizing and etching]
FIG. 14 is a diagram showing in detail the anodic oxidation process and the etching process in FIG. 13 in the case where such single-peak microprojections and multi-peak microprojections are mixed. Here, the applied voltage of the anodizing treatment is proportional to the pitch of the fine holes to be produced. In practice, however, the pitch of the fine holes varies depending on the grain boundaries of aluminum used for processing. However, in FIG. 14, it is assumed that there is no such variation, and that the fine holes are formed by regular arrangement. 14A to 14E are a plan view and a corresponding cross-sectional view cut out along the line aa, respectively, of the fine hole produced by each step.

  First, in this embodiment, after performing the first anodizing process with the low applied voltage V1, the etching process (hereinafter, referred to as the first process as appropriate) is performed, whereby FIG. As shown, a fine hole f1 with a basic pitch according to this low applied voltage V1 is produced. Here, the first anodic oxidation treatment is to produce a trigger for the subsequent anodic oxidation on the surface of the aluminum layer. In this case, the etching process in the first step may be omitted as necessary.

  Subsequently, in this embodiment, the second anodic oxidation process is performed with the applied voltage V2 (V2> V1) higher than that during the first anodic oxidation, and then the etching process is performed (hereinafter referred to as a second process as appropriate). ). Here, in this case, as shown in FIG. 14 (b), the applied voltage related to the second anodizing treatment among the fine holes f1 produced by the first anodizing treatment by increasing the applied voltage. Only the fine hole corresponding to the voltage is dug in the depth direction (indicated by reference numeral f2) and etched. Accordingly, if the applied voltage is varied in two steps, for example, fine holes having different depth distributions can be mixed in the second step.

  Subsequently, in this embodiment, the third anodic oxidation process is performed with the applied voltage V3 (V3> V2) higher than that during the second anodic oxidation, and then the etching process is performed (hereinafter referred to as a third process as appropriate). (FIG. 14 (c)). Here, the third step is a step for producing fine holes having different pitches. Therefore, in this step, the applied voltage is gradually increased from the applied voltage V2 in the second anodic oxidation step. Here, when the increase in the applied voltage is executed discretely (stepwise), the height distribution of the microprotrusions can be set discretely, and microholes having different depth distributions can be mixed. Further, when the increase in the applied voltage is continuously changed, the depth distribution can be set to a normal distribution.

  Further, in this third step, the application time of the specific voltage related to the anodic oxidation and the time of the etching process are set longer than those in the first and second steps, so that the first step, The fine holes f1 and f2 formed in the two steps are combined with the fine holes f1 and f2 so as to form a substantially flat fine hole at the bottom.

  Subsequently, in this embodiment, after performing the fourth anodic oxidation process with the applied voltage V4 (V4> V3) higher than that in the third anodic oxidation, the etching process is performed (hereinafter, referred to as a fourth process as appropriate). (FIG. 14D). Here, the fourth step is a step for producing a fine hole with a pitch according to a target interprotrusion interval, and the applied voltage V4 is a voltage corresponding to this pitch. In this fourth step, by increasing the applied voltage, a part of the fine hole dug deeply in the third step is further dug further, and the dug fine hole becomes a unimodal microprotrusion. The corresponding fine hole f4 is obtained.

  Subsequently, in this embodiment, the fifth anodic oxidation process is performed by the applied voltage V1 in the first process, and then the etching process is performed (FIG. 14E). Here, in the fifth step, a fine hole whose bottom surface is flattened by the third step and is not affected by the anodizing treatment of the fourth step, a fine hole is formed on the bottom surface. A plurality of microholes f5 for multi-peak protrusions are formed. Here, by adjusting the magnitude of the applied voltage V1 in the fifth step, the number of fine holes f5 formed on the bottom surface can be increased or decreased.

  In this series of steps, the fine holes f1 and f2 having different depths produced in the first and second steps are dug in the third step to produce a substantially flat microprojection f3 on the bottom surface. In the fourth step, a fine hole related to the single-peaked microprojection is formed, and in the fifth step, the bottom surface of the microprojection f3 having a flat bottom surface is processed to form a microhole related to the single-peaked microprojection. By controlling the applied voltage, the processing time, the etching processing time, etc. of the anodizing treatment according to these first to fourth steps, the depth of the fine hole produced in each step is controlled. By doing so, it is possible to control the height distribution of the microprojections and the height distribution of the multimodal microprojections. Needless to say, these first to fifth steps may be omitted, repeated, or integrated as necessary.

  In this embodiment, the height distribution is set to a normal distribution characteristic as described above, so that the anodizing step and the etching step are repeated five times, and the applied voltage in the first anodizing step is V1. The voltage applied in the second, third, fourth, and fifth anodic oxidation steps was 2V1, 3.5V1, 5V1, and V1, respectively. The anodizing treatment was performed for 100 seconds using an oxalic acid aqueous solution having a concentration of 0.02M. In the etching step, an etching process was performed for 45 seconds using an aqueous oxalic acid solution having a concentration of 0.02M, and then an etching process was performed for 110 seconds using an aqueous solution of phosphoric acid having a concentration of 1.0M.

  According to the above configuration, reflection due to internal reflection can be prevented by providing the light diffusion layer 4B on the base 2 side of the intermediate holding layer.

  Further, the intermediate holding layer is constituted by a molding resin layer provided with light diffusing particles, and in this molding resin layer, the distance between the particles of the light diffusing particles is relatively short on the substrate side. By forming a light diffusion layer, the distance between the particles of the light diffusion particles is relatively long on the microprojection side, and a light transmission layer is formed, thereby segregating the light diffusion particles mixed in the shaping resin layer. Or by laminating a light diffusing layer and a light transmitting layer of the same or different resin, an intermediate holding layer can be produced, and reflection due to internal reflection can be further reduced as compared with the conventional case.

  Various material layers that can reinforce the adhesion between the base material and the shaping resin layer by further providing a base material side intermediate holding layer between the light diffusion layer and the base material are applied. Thus, an antireflection film can be formed, and reflection due to internal reflection can be further reduced as compared with the conventional case.

  Moreover, by integrating such an antireflection film with a linear polarizing plate, the base material related to the minute protrusions can be shared with the base material related to the linear polarizing plate, thereby simplifying the configuration.

[Second Embodiment]
FIG. 15 is a diagram showing an antireflection article according to a second embodiment of the present invention in comparison with FIG. In this antireflection article 21, light diffusing particles are mixed into the base layer 7 (base material side intermediate holding layer) instead of the receiving layer (microprojection side intermediate holding layer) 6 of the intermediate holding layer 4. Instead, the underlayer 7 functions as a light diffusion layer. The antireflection article 21 is configured in the same manner as the antireflection film 1 according to the first embodiment except that the configuration regarding the light diffusion layer is different.

  As a result, in this antireflection article 21, the particle size and mixing amount of the light diffusing particles related to the light diffusing layer are set to be the same as those of the antireflection film 1 according to the first embodiment, and the receiving layer is formed by the base layer 7. 6 μm and 30 μm in thickness so that the adhesion between the substrate 6 and the substrate 2 can be sufficiently secured, and the underlayer 7 functions sufficiently as a light diffusion layer to prevent reflection due to internal reflection. More preferably, the thickness is 5 μm or more and 15 μm or less.

  When the intermediate holding layer is a laminate of the base material side intermediate holding layer and the microprojection side intermediate holding layer as in the second embodiment, light diffusion particles are mixed into the base material side intermediate holding layer. Even when the light diffusion layer is formed, the same effect as that of the first embodiment can be obtained. In this case, when the base material side intermediate holding layer is configured by applying various material layers capable of strengthening the adhesion between the base material and the shaping resin layer, the base material side intermediate holding layer is used. A light diffusing layer can be formed by mixing light diffusing particles into the glass.

  In addition, by constructing the antireflection film in this way and integrating the antireflection film with the linear polarizing plate, the base material related to the microprojections is shared with the base material related to the linear polarizing plate, thereby simplifying the configuration. Can be

[Results of comparative study]
FIG. 16 is a chart showing the examination results of the examples. In FIG. 16, the comparative example is a configuration in which the mixing of the light diffusing particles is stopped in the configuration of the first embodiment described above, and the light diffusing layer is not provided. More specifically, in the comparative example, a TAC film having a thickness of 80 μm was applied to the substrate 2. Further, pentaerythritol triacrylate or isophorone diisocyanate was diluted with a solvent to prepare a coating solution, and a base layer having a thickness of 1 μm was prepared by applying, drying and curing the coating solution. In addition, a 70 wt% and 30 wt% mixture of polyethylene glycol diacrylate and pentaerythritol triacrylate, or a 70 wt% and 30 wt% mixture of polyethylene glycol diacrylate and hexamethylene diisocyanate is diluted with a solvent to form a silicone oil-based polymerizability. A receptor layer was prepared with a thickness of 40 to 50 μm by preparing a coating solution for the receptor layer related to the resin, and applying the coating solution, drying, and shaping to produce microprojections.

  Therefore, in this comparative example, only the microprojection layer was produced, and the haze value by only this microprojection layer was 0.50, and the reflectance was 0.14%.

  In addition, Example 1, Example 2, and Example 3 are the configurations of the first embodiment described above. In the configuration of Comparative Example 1, the light diffusing particles are mixed by mixing the light diffusing fine particles into the coating liquid of the receiving layer. It is the structure which produced the light-diffusion layer by segregation. In Examples 1 to 3, the weight ratios of the light diffusing particles and the resin in the coating solution are set to 10%, 15%, and 20%, respectively, and thereby the haze values of only the light diffusing layer are 38.0 and 42, respectively. 0.0, 59.0%. In addition, the haze value of only this light-diffusion layer measured the hardening of the receiving layer, without performing a shaping process. In addition, the light diffusion particle mixed was based on acrylic resin, and the particle size was 2 μm to 6 μm.

  In the comparative example, a reflection with a sharp outline was observed due to internal reflection, and deterioration of the display screen was perceived by this reflection. However, in the first to third embodiments, even if the reflection cannot be completely prevented, the reflected object and its outline are observed in a blurred manner, and the deterioration of the quality due to the reflection is thereby greatly reduced. It was confirmed. In FIG. 16, this evaluation is indicated by “small”.

  Note that the degree of blurring of the object and the contour can be adjusted by the refractive index difference between the light diffusing fine particles and the resin around them, the size of the light diffusing fine particles, the P / V ratio, the thickness of the light diffusing layer, and the like. . When the haze value is too strong, the screen is observed with whiteness, but in the range of Examples 1-3, the reflection can be sufficiently reduced, and these Examples 1-3 are most suitable. The configuration differs depending on the preference of the user, and the range of the first to third embodiments is a range depending on the user.

  In the evaluation results shown in FIG. 16, a sufficiently small value is obtained for the haze value, and a sufficiently large value is obtained for the transmittance. It turns out that there is no problem. Further, it can be seen that even if the reflectance is 0.4% or less, it is possible to sufficiently prevent reflection of a front object due to reflection on the outermost surface.

  Thus, it can be seen that the reflection can be sufficiently reduced according to these embodiments.

[Other Embodiments]
The specific configuration suitable for the implementation of the present invention has been described in detail above. However, the present invention can be variously modified from the configuration of the above-described embodiment without departing from the spirit of the present invention, and further the conventional configuration. Can be combined.

  That is, in the above-described embodiment, the case where the base layer or the like is sequentially formed on the base material has been described. However, the present invention is not limited to this, and various production methods can be widely applied. It may be set so that the microprojections are produced integrally with the material, and the base material itself functions as a light diffusion layer by mixing light diffusion particles into the resin material according to this molding.

  Moreover, although the above-mentioned embodiment described the case where the anti-reflective article by a film shape was produced by the shaping process using a roll plate, this invention is not limited to this, The transparent base material which concerns on the shape of an anti-reflective article Depending on the shape, for example, when creating an antireflection article by processing a sheet using a shaping mold with a specific curved shape, such as a flat plate, the process related to the shaping process, the mold is the antireflection article It can change suitably according to the shape of the transparent base material which concerns on a shape.

  In the above-described embodiment, the case where an acrylate-based ultraviolet curable resin is applied to the shaping resin has been described. However, the present invention is not limited thereto, and various ultraviolet curable resins such as epoxy-based and polyester-based resins, or Also when using various materials such as acrylate-based, epoxy-based, polyester-based electron beam curable resins, urethane-based, epoxy-based, polysiloxane-based thermosetting resins, and various types of curing resins Can be widely applied.

Further, in the above-described embodiment, as shown in FIG. 1, the minute projection groups 5, 5A, 5B,... Are formed only on one surface of the base material 2 (directly or through another layer). However, the present invention is not limited to such a form. The microprojection groups 5, 5A, 5B,... May be formed on both surfaces of the substrate 2 (directly or via other layers).
Although not shown, in the antireflection film 1 of the present invention as shown in FIG. 1 and the like, the surface opposite to the surface on which the microprojections are formed of the substrate 2 (the lower surface of the substrate 2 in FIG. 1). Various adhesive layers are formed on the adhesive layer, and a release film (release paper) is laminated on the surface of the adhesive layer so as to be peelable. In such a form, the release film is peeled off to expose the adhesive layer, and the antireflection film 1 of the present invention can be laminated and laminated on the desired surface of the desired article by the adhesive layer. The antireflection performance can be easily imparted to a desired article. As the adhesive, various types of known adhesive forms such as a pressure-sensitive adhesive (pressure-sensitive adhesive), a two-component curable adhesive, an ultraviolet curable adhesive, a thermosetting adhesive, and a hot melt adhesive can be used. .

  Although not shown, in the antireflection film 1 of the present invention as shown in FIG. 1 etc., the microprojections 5, 5 A, 5 B,... The protective film may be peeled and removed at an appropriate time after carrying, carrying, buying and selling, post-processing or construction. In such a form, it is possible to prevent the antireflection performance from being deteriorated due to damage or contamination of the microprojection group during storage, transportation and the like.

  In the above-described embodiment, as shown in FIG. 1 and FIG. 2A, the surface connecting valley bottoms (minimum points of height) between adjacent minute protrusions is a flat surface having a constant height. However, the present invention is not limited to this, and as shown in FIG. 17, the envelope surface connecting the valley bottoms between the microprotrusions undulates with a period D (that is, D> λmax) equal to or longer than the longest wavelength λmax of the visible light band. It is good also as a structure. In addition, the periodic undulation is only in one direction (for example, the X direction) on the XY plane (see FIG. 2) parallel to the front and back surfaces of the substrate 2 and at a constant height in the direction (for example, the Y direction). There may be waviness or both directions in the XY plane (X direction and Y direction) may have undulations. The uneven surface 9 wavy with a period D satisfying D> λmax is superimposed on a microprojection group consisting of a large number of microprojections, so that the reflected light remaining without being completely prevented from being reflected by the microprojection group is scattered and remains. Reflected light, particularly specularly reflected light, can be made more difficult to visually recognize, and the antireflection effect can be further improved.

In addition, when the period D of the uneven surface 9 has a distribution that is not constant over the front surface, the frequency distribution of the distance between the protrusions is obtained for the uneven surface, and the average value is D _AVG and the standard deviation is Σ. When
D _MIN = D _AVG -2Σ
Designed as an alternative to period D with a minimum inter-protrusion distance defined as That is, conditions that can sufficiently exhibit the scattering effect of the reflected light of the microprojections are as follows:
D _MIN > λmax
It is. Usually, D or D _MIN is 1 to 200 μm, preferably 10 to 100 μm.
An example of a specific manufacturing method for forming a concavo-convex microprotrusion group having an uneven surface 9 in which the envelope surface connecting the valley bottoms of the microprotrusions is D (or D _MIN )> λmax is as follows. is there. That is, in the manufacturing process of the roll plate 13, a concavo-convex shape corresponding to the concavo-convex shape of the concavo-convex surface 9 is formed on the surface of a cylindrical (or columnar) base material by sandblasting or mat (matte) plating. Next, an appropriate intermediate layer is formed directly or if necessary on the uneven surface, and then an aluminum layer is laminated. Thereafter, an aluminum layer formed with a surface shape corresponding to the uneven surface is subjected to anodizing treatment and etching treatment in the same manner as in the above embodiment to form a microprojection group including microprojections 5, 5A, 5B. To do.

  Further, in the above-described embodiment, the case where the fine hole is produced by repeating the anodizing treatment and the etching treatment has been described. However, the present invention is not limited to this, and the case where the fine hole is produced by applying a photolithography technique. Can also be widely applied.

  In the above-described embodiment, the case where the antireflection article is arranged on the panel surface of the image display panel has been described. However, the present invention is not limited to this. The present invention can be widely applied to the case where it is arranged on the surface. In this case, in the cosmetic film material, it is possible to prevent reflection due to internal reflection, so that the makeup film that is extremely matte, the decorative film that does not impair the grain pattern, etc. relating to makeup as seen from various directions, etc. Can be provided.

  Moreover, although the above-mentioned embodiment described the case where the anti-reflective article by a film shape is arrange | positioned to the image display panel which concerns on an anti-reflective film, this invention is applicable not only to this but to various uses. Specifically, it should be applied to applications that are placed on the back surface (image display panel side) of the surface side member such as a touch panel, various window materials, various optical filters, etc. installed on the screen of the image display panel through a gap. Can do.

  In addition, it is arranged on the glass plate surface (external side) used for the store show window and product display box of the store, the display window and display box of the exhibition of the museum, or both of the front and back surfaces (product or display side). May be. In this case, it is possible to improve the visibility for customers and spectators of products, artworks, etc. by preventing light reflection on the surface of the glass plate.

  Further, the present invention can be widely applied to the case where the lens or prism is used on various optical devices such as glasses, a telescope, a camera, a video camera, a gun sighting mirror (sniper scope), binoculars, a periscope, and the like. In this case, the visibility by preventing light reflection on the lens or prism surface can be improved. Furthermore, it can also be applied to the case where it is arranged on the surface of a printed part (characters, photos, drawings, etc.) of a book to prevent light reflection on the surface of characters and the like and improve the visibility of characters and the like. In addition, it should be placed on the surface of signs (posters, posters, various other stores, streets, exterior walls, etc.) (road guidance, maps, smoking cessation, entrances, emergency exits, no entry, etc.) to improve visibility. Can do. In addition, a light entrance surface of a window material for a lighting fixture using an incandescent bulb, light emitting diode, fluorescent lamp, mercury lamp, EL (electroluminescence), etc. By arranging it on the side, it is possible to prevent the light reflection of the light incident surface of the window material, reduce the reflection loss of the light source light, and improve the light utilization efficiency. Furthermore, it can arrange | position on the display window surface (display observer side) of a timepiece and other various measuring devices, the light reflection of these display window surfaces can be prevented, and visibility can be improved.

  Furthermore, it is placed on the inside, outside, or both sides of the windows of the cockpits (driver's cabs, wheelhouses) of vehicles such as automobiles, railway vehicles, ships, and aircraft to prevent reflection of indoor and outdoor light from the windows. Thus, it is possible to improve the visibility of the outside world of the driver (driver, driver). Furthermore, it can be arranged on the surface of a night vision device lens or window material used for crime prevention monitoring, gun sighting, astronomical observation, etc. to improve visibility at night and in the dark.

  Furthermore, the surface of the transparent substrate (window glass, etc.) that constitutes windows, doors, partitions, wall surfaces, etc. of buildings such as houses, stores, offices, schools, hospitals, etc. (inside, outside, or both sides) It is possible to improve the visibility of the outside world or the daylighting efficiency. Furthermore, it can arrange | position on the surface of a greenhouse, the transparent sheet | seat of an agricultural greenhouse, or a transparent board (window material), and can improve the sunlight lighting efficiency. Furthermore, it can arrange | position on the solar cell surface and can improve the utilization efficiency (power generation efficiency) of sunlight.

  Further, it can be widely applied to an opaque portion other than a transparent portion in order to prevent the reflection widely.

  Furthermore, in the above-described embodiment, the wavelength band of the electromagnetic wave for preventing reflection is exclusively the visible light band (all or part of the visible light band), but the present invention is not limited to this, and the electromagnetic wave for preventing reflection. May be set to a wavelength band other than visible light rays such as infrared rays and ultraviolet rays. In that case, the shortest wavelength Λmin in the wavelength band of the electromagnetic wave may be set to the shortest wavelength in which the antireflection effect in the wavelength band of infrared rays, ultraviolet rays, etc. is desired in each conditional expression. For example, when it is desired to prevent reflection in the infrared band where the shortest wavelength Λmin is 850 nm, the distance d between adjacent protrusions (or its maximum value dmax) may be designed to be 850 nm or less, for example, d (dmax) = 800 nm. . In this case, an antireflection effect cannot be expected in the visible light band (380 to 780 nm), and an antireflection article exhibiting an antireflection effect for infrared rays having a wavelength of 850 nm or more can be obtained.

  In the various exemplary embodiments described above, when the film-shaped antireflection article of the present invention is disposed on the front surface, back surface, or both front and back surfaces of a transparent substrate such as a glass plate, it is disposed and covered over the entire surface of the transparent substrate. In addition, it can be arranged only in a partial area. As an example of this, for example, for a single window glass, a film-shaped antireflection article is attached to the indoor side surface only with an adhesive in a square area at the center, and an antireflection article is provided in the other areas. The case where it does not stick can be mentioned. In the case where the antireflection article is arranged only in a partial area of the transparent substrate, it is easy to visually recognize the presence of the transparent substrate without special display or a collision prevention fence, etc. The effect of reducing the risk of collision and injury, and the effect that both the prevention of peeping indoors (indoors) and the transparency of the transparent substrate (in the region where the antireflection article is disposed) can be achieved.

1,21 Antireflection article 2,107,108 Base material 4,6 Intermediate holding layer, receiving layer (molding resin layer)
5, 5A, 5B Microprojections 5X Microprojection layer 7 Underlayer 8 Light diffusion particles 10 Manufacturing process 11 Die 13 Roll plate 14, 15 Roller 100 Image display device 101 Backlight device 102 Image display panel 103 Liquid crystal cell 104, 105 Linearly polarized light Plate 106 Optical functional layer g Groove

Claims (6)

In the antireflection article in which the microprotrusions are closely arranged and the interval between the adjacent microprotrusions is equal to or less than the shortest wavelength of the wavelength band of the electromagnetic wave to prevent reflection,
The microprotrusions are held on the surface of the substrate by a transparent film material through an intermediate holding layer,
An antireflection article comprising a light diffusing layer comprising light diffusing particles on the substrate side of the intermediate holding layer. The intermediate holding layer is
A resin layer for shaping to be subjected to a shaping treatment of the microprotrusions provided with the light diffusing particles,
In the molding resin layer, the inter-particle distance of the light diffusing particles is relatively shortened on the base material side to form the light diffusing layer,
2. The reflection according to claim 1, wherein in the shaping resin layer, a light transmission layer that suppresses scattering of transmitted light is formed by relatively increasing a distance between the light diffusion particles on the minute protrusion side. Prevention article. The antireflection article according to claim 1, wherein a base material side intermediate holding layer is further provided between the light diffusion layer and the base material. The intermediate holding layer is
It is a laminate of the substrate side intermediate holding layer and the microprojection side intermediate holding layer,
The antireflection article according to claim 1, wherein the light diffusion particles are mixed into the base-side intermediate holding layer and the light-diffusing layer is formed by the base-side intermediate holding layer. The antireflection article according to any one of claims 1 to 4, wherein the antireflection article is laminated and integrated with a linear polarizing plate.   The image display apparatus which has arrange | positioned the antireflection article | item in any one of Claims 1-4 on the panel surface of an image display panel.