JP6764635B2 - Anti-reflective articles and image display devices - Google Patents

Description

The present invention relates to an antireflection article for antireflection by closely arranging a large number of microprojections at intervals equal to or less than the shortest wavelength of the wavelength band of electromagnetic waves for antireflection.

In recent years, with respect to an antireflection film which is a film-shaped antireflection article, a method for preventing reflection by arranging a large number of microprojections closely on the surface of a transparent base material (transparent film) has been proposed (patent Refer to Documents 1 to 3). This method utilizes the principle of the so-called moth eye structure, in which the refractive index for incident light is continuously changed in the thickness direction of the substrate, thereby discontinuous interface of the refractive index. Is intended to prevent reflection.

In the antireflection article related 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) in the wavelength band of the electromagnetic wave for antireflection. To. Further, each microprojection is produced so as to be planted on a transparent base material and the cross-sectional area gradually decreases (tapered) toward the tip side of the transparent base material.

Further, Patent Document 4 discloses a configuration in which a base portion of a microprojection is created so as to exhibit a swell with a period larger than that of the microprojection formation cycle for this type of antireflection article. Further, Patent Document 4 discloses a configuration in which microprojections are formed on the surface of a base material by a shaping process using a shaping resin to prepare an antireflection article of this type.

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, so that the reflection and the like can be reduced and the visibility of the display screen can be improved. However, in the image display panel, for example, there is a boundary in which the refractive index changes abruptly, such as the boundary between the glass substrate on the exit surface side and the film material constituting the liquid crystal cell, and the boundary is foreign. Light is reflected. As a result, even when the antireflection film is attached, there is a problem that reflection occurs due to this internal reflection and the quality of the display screen is impaired.

Japanese Unexamined Patent Publication 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 the reflection due to internal reflection of an antireflection article having a moth-eye structure as compared with the conventional case.

The present inventor has repeated diligent research in order to solve the above problems, and has come up with the idea of providing a light diffusing layer provided with light diffusing particles in the vicinity of a boundary that causes a problematic internal reflection. Has been completed.

Specifically, the present invention provides the following.

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

According to (1), the internally reflected light can be scattered at a location close to the source, and the internally reflected light can be efficiently scattered to reduce the reflection due to the internal reflection. Further, even if the internally reflected light is sufficiently scattered by the light diffusing layer by forming the moth-eye structure on the surface by reducing the reflection by the light diffusing layer, the scattered light generated as a result Scattering on the outermost surface can be sufficiently reduced. As a result, a large amount of light diffusing particles related to the light diffusing layer are mixed to efficiently reduce reflection due to internal reflection, and whiteness of the display screen due to deterioration of the haze value can be effectively avoided.

(2) In (1)
The intermediate holding layer
A molding resin layer provided with the light diffusing particles and used for the shaping treatment of the microprojections.
In the shaping resin layer, the distance between the light diffusing particles is relatively short on the base material side to form the light diffusing layer.
In the shaping resin layer, the distance between the particles of the light diffusing particles is relatively long on the microprojection side, and an antireflection layer is formed on the microprojection side to suppress scattering of transmitted light. Goods.

According to (2), an intermediate holding layer is produced by segregation of light diffusing particles mixed in the molding resin layer, or by laminating a light diffusing layer and a light transmitting layer with the same or different resin, and internal reflection is performed. It is possible to further reduce the reflection caused by the image as compared with the conventional case.

(3) In (1) or (2)
An antireflection article in which an intermediate holding layer on the base material side is further provided between the light diffusion layer and the base material.

According to (3), various material layers capable of strengthening the adhesion between the base material and the resin layer for shaping are applied to form an antireflection article, and reflection due to internal reflection is conventionally performed. In comparison, it can be further reduced.

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

According to (4), when various material layers capable of strengthening the adhesion between the base material and the molding resin layer are applied to form the base material side intermediate holding layer, the base material side is formed. 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 microprojections can be shared with the base material related to the linear 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), with respect to the image display device in which the antireflection article having the moth-eye structure is arranged, the reflection due to the internal reflection can be further reduced as compared with the conventional case.

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

It is a conceptual perspective view which shows the antireflection article which concerns on 1st Embodiment of this invention. It is a figure which shows the detail of the multimodal microprojection which concerns on the antireflection article of FIG. It is a photograph of multimodal microprojections. It is a figure which provides the explanation of the adjacent protrusion. It is a figure which provides the explanation of the maximum point. It is a figure which shows the Delaunay figure. It is a frequency distribution map used for measuring the distance between adjacent protrusions. It is a frequency distribution map used for the explanation of the height of a microprojection. It is a frequency distribution diagram which is used to explain the distribution of the height of a microprojection. It is a chart which shows the measurement result of the height distribution of a microprojection. It is a figure which shows the manufacturing process of the antireflection article of FIG. It is a figure which shows the roll plate which concerns on the antireflection article of FIG. It is a figure which shows the manufacturing process of the roll plate of FIG. It is a figure which provides the detailed description of anodizing treatment and etching treatment. It is a conceptual perspective view which shows the antireflection 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 of the case where the envelope surface exhibits a swell.

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

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

Here, the linear polarizing plates 104 and 105 sandwich an optical functional layer (so-called polarizer) 106 that functions as a linear polarizing plate by the base materials 107 and 108, which are transparent film materials that function as protective layers, respectively. It is formed. In this embodiment, among these linear polarizing plates 104 and 105, in the exit surface side linear polarizing plate 105, the exit surface side base material 108 is configured to also serve as the base material 2 of the antireflection film 1. Therefore, the antireflection film 1 is manufactured integrally with the linear polarizing plate, whereby the overall configuration can be simplified and the overall thickness can be reduced. The antireflection film 1 may be manufactured separately from the linear polarizing plate.

Here, the antireflection film 1 is produced by closely arranging a large number of microprojections 5, 5A, and 5B on the surface of the base material 2 in the shape (form) of the transparent film. Here, the base material 2 is, for example, a cellulose-based resin such as TAC (Triacetylcellulose), an acrylic resin such as PMMA (polymethylmethacrylate), a polyester-based resin such as PET (Polyethylene terephthalate), and PP (polypropylene). Polyester resin such as PVC (polyvinyl chloride), vinyl resin such as PVC (polycarbonate), and various transparent resin films such as PC (Polycarbonate) can be applied. When the antireflection film 1 is used in an image display device, TAC or acrylic is preferably used as the base material 2.

The antireflection film 1 is an uncured resin layer (a so-called shaping resin layer, which is also appropriately referred to as a receiving layer) which is a receiving layer having a fine uneven shape composed of microprojections on the base material 2. Is formed, and the receiving layer 4 is shaped and cured, whereby microprojections are closely arranged on the surface of the base material 2. In this embodiment, an acrylate-based ultraviolet curable resin, which is one of the shaping resins to be subjected to the shaping treatment, is applied to the receiving layer 4, and the receiving layer 4 is formed on the base material 2 by the ultraviolet curable resin layer. It is formed. The antireflection film 1 is manufactured so that the refractive index gradually changes in the thickness direction due to the uneven shape due to the minute protrusions, and the reflection of incident light is reduced in a wide wavelength range by the principle of the moth-eye structure. Further, in the antireflection film 1, the microprojection layer 5X is formed by the close arrangement of the microprojections 5, and the intermediate holding layer that holds the microprojection layer 5X on the base material 2 is shaped by the receiving layer 4. It will be composed of a resin layer for use.

In the antireflection film 1, if necessary, the base layer (which is the base material side intermediate holding layer) for strengthening the adhesion of the receiving layer 4 which is the intermediate holding layer is formed on the base material 2 side of the intermediate holding layer. Will be 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, and for example, an ultraviolet curable resin or a thermosetting resin can be used. Applies. When an ultraviolet curable resin is used, half-cure treatment or the like is often applied. Here, if the difference in refractive index between the intermediate holding layer on the base material side and the intermediate holding layer on the microprojection side is large, the interlayer reflection between the intermediate holding layer on the base material side and the intermediate holding layer on the microprojection side becomes large, so this difference in refractive index is as much as possible. It is preferably small, and the difference in refractive index is preferably smaller than 0.03. Further, when a transparent film material such as PET film is applied to the base material 2, an intermediate holding layer on the base material side is provided, and the adhesive force is further strengthened on the base material side of the intermediate holding layer on the base material side. In addition, an easy-adhesion layer whose refractive index is adjusted so as to reduce interfacial 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 sufficiently larger than the shortest wavelength used for antireflection and capable of scattering transmitted light, and as a result, the root portion of the microprojection 5 is formed. It is composed of larger sizes in each stage. More specifically, the light diffusing particles are composed of a particle size of 2 μm or more and 10 μm or less.

Further, in this embodiment, as shown by being partially enlarged by reference numeral A, in the intermediate holding layer formed by the receiving layer 4, the light diffusing particles 8 are segregated toward the base material 2, that is, the base material 2 side. The interparticle distance of the light diffusing particles is relatively short, the interparticle distance gradually increases as the distance from the base material 2 increases, and the interparticle distance becomes relatively long on the microprojection 5 side. As a result, in this embodiment, in this intermediate holding layer, a light diffusing layer 4B having light diffusing particles is produced on the side close to the base material 2. Further, the intermediate holding layer is formed by the shaping resin layer to be subjected to 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 inter-particle distance is relatively short to form the light diffusing layer 4B, and the inter-particle distance of the light diffusing particles is relatively long on the microprojection 5 side to suppress the scattering of transmitted light. Is formed. By producing the light diffusing layer 4B and the light transmitting layer 4A by segregation of the light diffusing particles 8 in this way, in this embodiment, the distance between the particles gradually increases as the distance from the base material 2 increases, and the light diffusing layer Although the boundary between 4B and the light transmitting layer 4A is configured so as not to be clearly grasped, as indicated by reference numeral B, the boundary between the light diffusing layer 4B and the light transmitting layer 4A is configured to be clearly grasped. You may. In the case of such a configuration, after applying the coating liquid according to the light diffusing layer 4B, the light transmitting layer 4A is not mixed with the light diffusing particles made of the same or different resin material as the light diffusing layer 4B. By applying the coating liquid, or after applying the coating liquid related to the light diffusing layer 4B and curing it, light diffusing particles made of the same or different resin material as the light diffusing layer 4B are mixed. By applying the coating liquid according to the non-light transmitting layer 4A, the light diffusing layer B and the light transmitting layer 4A can be laminated and produced.

When the light diffusion layer 4B is provided in this way, the internally reflected light can be scattered on the side close to the source of the internally reflected light by the light diffusion layer 4B, so that the internally reflected light can be efficiently scattered. Reflection due to internal reflection can be reduced. Further, even if the internally reflected light is sufficiently scattered by the light diffusion layer due to the moth-eye structure formed on the surface by reducing the reflection by the light diffusion layer, the scattered light generated as a result It is possible to reduce reflection and scattering on the outermost surface. As a result, a large amount of light diffusing particles related to the light diffusing layer are mixed to efficiently reduce reflection due to internal reflection, and whiteness of the display screen due to deterioration of the haze value can be effectively avoided.

More specifically, according to the results of the experiment, a film material having a haze value of 38%, 42%, and 59%, respectively, was applied to the base material 2 to produce microprojections to obtain an antireflection film. As a result, the haze values were 20%, 25%, and 30%, respectively, and it was confirmed that the haze value was remarkably reduced by providing the microprojections 5. Such a decrease in the haze value is caused by the diffused light diffused by the light diffusing layer being reflected or diffused on the surface of the film material when the microprojections are not provided, thereby causing the inside of the light diffusing layer. While the haze value actually measured as a film material is larger than the haze value, when microprojections are arranged, the reflection and diffusion on such a surface are reduced, so that the internal haze value is increased. It is considered that the haze value with a value substantially equal to is measured by the film material. As a result, the reflection due to internal reflection can be efficiently reduced, and the phenomenon that the display screen becomes whitish due to the prevention of reflection by the diffusion of the internally reflected light can be sufficiently suppressed in practical use. it can. In the experiments using these film materials, the front reflectance by arranging the minute protrusions was 0.18% in each case, and even if the internally reflected light was scattered, the reflectance was sufficiently reduced by the moth-eye structure. It was confirmed that it could be done. When the internally reflected light is diffused in this way, the glare of the display screen generated by arranging the film material having a moth-eye structure on the panel surface of the image display panel can be sufficiently suppressed.

Here, in order to secure the effect of reducing reflection due to such internal reflection, it is necessary to sufficiently scatter the internally reflected light, but if the degree of scattering is too large, the display screen becomes whitish. By being observed, the visibility is rather deteriorated. Therefore, the light diffusing particles 8 are added in an amount of 20% or more and 50% or less based on the weight ratio with respect to the light diffusing layer 4B. Further, even if the addition amount is set in this way, when the thickness of the light diffusing layer 4B is thin, the transmitted light cannot be sufficiently diffused and reflection occurs, whereas the thickness of the light diffusing layer 4B is large. If it is thick, the transmitted light will be diffused too much. Thereby, in this embodiment, the intermediate holding layer 4 is composed of a thickness of 5 μm or more and 50 μm or less. In the configuration indicated by reference numeral B, the light diffusion layer 4B has a thickness of 5 μm or more and 50 μm or less. Further, for the light diffusing particles, various materials such as acrylic and styrene resin materials having different refractive indexes and white materials typified by silica are widely applied to the resin materials constituting the receiving layer. be able to.

By producing the light diffusing layer 4B in this way, 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. To. The haze value is preferably 20 or more and 40 or less. When the haze value is low, the effect of blurring the reflection of internal reflection is weak, and when the haze value is high, whitishness becomes conspicuous.

[Shape of microprojections]
In the antireflection film 1, monomodal microprojections and multimodal microprojections 5A and 5B are set to coexist. Here, the multimodal microprojections 5A and 5B are microprojections having a plurality of vertices, and the monomodal microprojections are microprojections having only one apex. Thereby, in this embodiment, the scratch resistance of the antireflection article is improved.

That is, FIG. 2 is a diagram provided for explaining the multimodal microprojections 5A and 5B and the monomodal microprojections. Note that FIG. 2 is a diagram schematically shown for ease of understanding, and FIG. 2 (a) is a diagram showing a cross section taken along a polygonal line connecting the vertices of continuous microprojections. In FIGS. 2B and 2C, the xy direction is the in-plane direction of the base material 2, and the z direction is the height direction of the microprojections.

In the antireflection film 1, many microprojections 5 are gradually cut along a cross-sectional area (a plane orthogonal to the height direction (a plane parallel to the XY plane in FIG. 2) toward the apex away from the base material 2). The cross-sectional area of) becomes smaller, and one vertex is produced. However, some of them have a groove g formed at the tip portion and have two vertices (5A) and three vertices (5B) as if a plurality of microprojections were combined. Further, those having four or more vertices (not shown) can exist. The shape of the unimodal microprojection 5 can be roughly approximated by a round shape at the top such as a rotating paraboloid or a pointed shape at the apex such as a cone. On the other hand, the shapes of the multimodal microprojections 5A and 5B are roughly approximated by cutting a groove-shaped recess in the vicinity of the top of the monomodal microprojections 5 and dividing the top into a plurality of peaks.

The multimodal microprojection having a plurality of such vertices has a relatively thicker hem with respect to the dimension near the apex as compared with the monomodal microprojection, and is compared with the multimodal microprojection. The circumference is long. Therefore, it can be said that the multimodal microprojections are superior in mechanical strength to the monomodal microprojections. As a result, when there are multimodal microprojections having a plurality of vertices, the antireflection article has improved scratch resistance as compared with the case where only monomodal microprojections are used. Specifically, when an external force is applied to the antireflection article, the external force is distributed and received at more vertices than when only the monomodal microprojections are applied, so that the external force applied to each apex is reduced and the microprojections are microprojections. Can be made less likely to be damaged, thereby reducing local deterioration of the antireflection function and further reducing the occurrence of poor appearance. Further, even if the microprojection is damaged, the area of the damaged portion can be reduced. Further, the multimodal microprojections are lower than the peaks of the multimodal microprojections and higher than the multimodal microprojections by first receiving the external force by each peak portion and causing sacrificial damage. It is possible to prevent the wear of low-pitched microprojections. This also reduces the local deterioration of the antireflection function and further reduces the occurrence of poor appearance.

It is needless to say that the multimodal microprojections can improve the scratch resistance due to their presence, but if they are not sufficiently present, the effect of improving the scratch resistance cannot be sufficiently exhibited. From this point of view, it is desirable that the ratio of the number of multimodal microprojections in all the microprojections existing on the surface is 10% or more. In particular, in order to sufficiently exert the effect of improving the scratch resistance of the multimodal microprojections, it is desirable that the ratio of the multimodal microprojections is 30% or more, preferably 50% or more. Further, since the difficulty of controlling the manufacturing process increases as the ratio of the multimodal microprojections increases, the ratio is preferably 90% or less, more preferably 80% or less. Further, by setting the abundance ratio of the unimodal microprojections in this way, sticking can be made less likely to occur, and as a result, deterioration of the characteristics due to sticking can be effectively avoided. Further, when the monomodal microprojections and the multimodal microprojections are mixed, the reflectance can be reduced in a wide wavelength band as in the case where the monomodal microprojections having different aspect ratios are mixed. it can.

The aspect ratio is defined as H / W, which is the ratio obtained by dividing the height H of the minute protrusions by the diameter W (which can also be called width or thickness) at the valley bottom. Here, the diameter at the valley bottom coincides with the diameter (of the bottom surface) of the cylinder if the shape of the microprojection near the valley bottom is a cylinder. If the shape near 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 bottoms and the microprojection differs depending on the in-plane direction, the maximum value is set to the microprojection. The diameter of. For example, when the bottom surface shape of the microprojection is elliptical, the diameter is the major axis thereof. When the bottom surface of the microprojection is polygonal, the diameter is the maximum diagonal length. Further, when the width of the valley bottom (the region consisting of the minimum points of the height) is smaller than the diameter and is 20% or less, the average value (H / W) ave of the aspect ratio H / W of each microprojection is. In terms of design, it can be regarded as Have / Dave.

FIG. 3 is a photograph showing a plurality of microprojections with a plurality of vertices, FIG. 3 (a) is by AFM, and FIGS. 3 (b) and 3 (c) are by SEM. In FIG. 3 (a), a groove g and a microprojection having three vertices, and a groove g and a microprojection having two vertices (two-peak multimodal microprojections) can be seen, and FIG. 3 (b) Can be seen in the groove g and the microprojections having four vertices (multimodal microprojections with four peaks), and the groove g and the microprojections having two vertices. Microprojections with three vertices (three-peak multimodal microprojections), grooves g and microprojections with two vertices can be seen.

[Distance between adjacent protrusions]
The microprojections produced on the antireflection film 1 are closely arranged so that the distance d between adjacent microprojections is equal to or less than the shortest wavelength Λmin (d ≦ Λmin) in the wavelength band of the electromagnetic wave for which antireflection is to be achieved. In this embodiment, since the main purpose is to arrange it on the image display panel to improve visibility, this shortest wavelength is set to the shortest wavelength (380 nm) in the visible light region in consideration of individual differences and viewing conditions. The interval d is set to 100 to 300 nm in consideration of variation. Further, the adjacent microprojections related to this interval d are so-called adjacent microprojections, and are protrusions in which the hem portion of the microprojections, which is the base portion on the base material 2 side, is in contact. In the antireflection film 1, the microprojections are closely arranged, and when a line segment is created by sequentially tracing the valleys between the microprojections, a large number of polygonal regions surrounding the microprojections are connected in a plan view. A mesh-like pattern will be produced. The adjacent microprojections related to the interval d are projections that share a part of the line segments constituting this mesh-like pattern.

The microprojections are defined in more detail as follows. Anti-reflection by the moth-eye structure is intended to prevent reflection by continuously changing the effective refractive index at the interface between the surface of the transparent base material and the medium adjacent to it in the thickness direction. It is necessary to satisfy the conditions of. Regarding the distance between protrusions, which is one of these conditions, when the minute protrusions are regularly arranged at regular intervals, as disclosed in Japanese Patent Application Laid-Open No. 50-70040, Japanese Patent No. 4632589, etc., they are adjacent to each other. The interval d of the microprojections to be formed is the period P (d = P) of the projection arrangement. As a result, when the longest wavelength of the visible light band is λmax and the shortest wavelength is λmin, the minimum necessary condition for achieving the antireflection effect at the longest wavelength of the visible light band is Λmin = λmax. Since P ≦ λmax and the necessary and sufficient condition for exhibiting the antireflection effect for all wavelengths in the visible light band is Λmin = λmin, P ≦ λmin.

The wavelengths λmax and λmin may have some width depending on the observation conditions, light intensity (luminance), individual differences, etc., but are standardly set to λmax = 780 nm and λmin = 380 nm. A preferable condition in which the antireflection effect for all wavelengths in the visible light band can be more reliably achieved is d ≦ 300 nm, and a more preferable condition is an oblique direction (45 degrees or more with respect to the normal of the surface of the base material 2). D ≦ 200 nm from the viewpoint of reducing the white turbidity when viewed from (the direction forming the angle). The lower limit of the period d is usually d ≧ 50 nm, preferably d ≧ 100 nm, for the reason of exhibiting the antireflection effect and ensuring the isotropic property (low angle dependence) 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 microprojections are irregularly arranged as in this embodiment, the distance d between adjacent microprojections will vary. More specifically, as shown in FIG. 4, when the microprojections are not regularly arranged at regular intervals when viewed in a plan view from the normal direction of the front surface or the back surface of the base material, the repetition period P of the projections P. Depending on the situation, the distance d between adjacent protrusions cannot be specified, and even the concept of adjacent protrusions becomes questionable. Therefore, in such a case, it is calculated as follows.

(1) That is, first, an in-plane arrangement of protrusions (projection arrangement) using an atomic force microscope (Atomic Force Microscope (hereinafter referred to as AFM)) or a scanning electron microscope (Scanning Electron Microscope (hereinafter referred to as SEM)). (Plan view shape) is detected. Note that 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 microprojection group, it can be said that this photograph shows the in-plane distribution of the height by the brightness.

(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 whose height is larger (maximum value) than any point in the vicinity thereof. As a method of obtaining the maximum point, (a) a method of sequentially comparing the plane coordinates on the enlarged photograph of the plan view shape and the height data obtained from the corresponding cross-sectional shape, and (b). Various methods can be applied, such as a method of obtaining the maximum point by image processing of a plan view magnified photograph obtained by converting the height distribution data in the plane coordinates on the substrate obtained by AFM into a two-dimensional image. FIG. 4 is an enlarged photograph by AFM (the image density corresponds to the height), and FIG. 5 is a diagram showing the detection result of the maximum point by processing the image data related to the enlarged photograph shown in FIG. The points indicated by black dots in the figure are the maximum points of each protrusion. In this processing, image data was processed in advance by a low-pass filter having a Gaussian characteristic of 4.5 × 4.5 pixels, thereby preventing erroneous detection of a maximum point due to noise. Further, the maximum point was obtained in units of 1 nm (= 1 pixel) by sequentially scanning a filter for detecting the maximum value with 8 pixels × 8 pixels.

(3) Next, a Delaunay diagram (Delaunay Diagram) having the detected maximum point as a mother point is prepared. Here, the Delaunay diagram is obtained by defining the Voronoi regions adjacent to each other as adjacent matrix points and connecting the adjacent matrix points with a line segment when the Voronoi division is performed with each maximum point as the matrix point. It is a net-like figure composed of an aggregate of triangles. Each triangle is called a Dronay triangle, and the sides of each triangle (the line segment connecting adjacent mother points) are called the Dronay line. FIG. 6 is a diagram in which the Delaunay diagram (a diagram represented by a white line segment) obtained from FIG. 5 is superimposed on the original image according to FIG. The Delaunay diagram has a dual relationship with the Voronoi diagram. Voronoi division refers to dividing a plane by a network figure consisting of a collection of closed polygons defined by perpendicular bisectors of line segments (Dronoi lines) connecting adjacent matrix points. The 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 Dronay 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 prepared from the Delaunay diagram of FIG. As shown by reference numerals 5A and 5B in FIG. 4, when a recess such as a groove is present at the top of the protrusion, or when the top is divided into a plurality of peaks, such a recess is obtained from the obtained frequency distribution. Data due to the microstructure in which a recess exists at the top of the protrusion and the microstructure in which the top is divided into a plurality of peaks are removed, and only the data of the protrusion body itself is selected to create a frequency distribution.

Specifically, in the microstructure in which a recess exists at the top of the protrusion and the microstructure related to the multimodal microprojection in which the top is divided into a plurality of peaks, the microstructure does not have such a microstructure. From the numerical range in the case of minute protrusions, the distance between adjacent maximum points is clearly significantly different. As a result, by utilizing this feature and removing the corresponding data, only the data of the protrusion body itself is selected and the frequency distribution is detected. More specifically, for example, from the enlarged photograph of the microprojections (groups) shown in FIG. 4 in a plan view, about 5 to 20 unimodal microprojections adjacent to each other are selected, and the distance between the adjacent maximum points is selected. The value of is sampled, and the value clearly deviates from the numerical range obtained by sampling (usually, the value is 1/2 or less of the mean distance between adjacent maximum points obtained by sampling). The frequency distribution is detected by excluding the data). In the example of FIG. 7, data having a distance between adjacent maximum points of 56 nm or less (the leftmost hill indicated by arrow A) is excluded. Note that FIG. 5 shows a frequency distribution before such an exclusion process is performed. Incidentally, such an exclusion process may be executed by setting the filter for maximum inspection described above.

(5) The mean 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 mean value d _AVG and the standard deviation σ are obtained, in the example of FIG. 7, the mean value d _AVG = 158 nm and the standard deviation σ = 38 nm. As a result, the maximum value of the distance d between adjacent protrusions is dmax = d _AVG + 2σ, and in this example, dmax = 234 nm.

The height of the protrusion is defined by applying the same method. In this case, the difference in relative height of each maximum point position from a specific reference position is acquired from the maximum point obtained in (2) above and made into a histogram. FIG. 8 is a diagram showing a histogram of the frequency distribution of the protrusion height H with the protrusion base position obtained in this way as a reference (height 0). From the frequency distribution based on this histogram, the average value _HAVG of the protrusion height and the standard deviation σ are obtained. 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 the multimodal microprojection, since the plurality of vertices are provided, these plurality of data are mixed for one projection. Therefore, in this case, the highest apex among the plurality of vertices belonging to the same microprojection at the foot is adopted as the protrusion height of the microprojection to obtain the frequency distribution. When all the peaks sharing the foot are at the same height, the same height is used as the height of the microprojections.

As the reference position when measuring the height of the above-mentioned protrusions, the valley bottom (minimum point of height) between the adjacent minute protrusions is used as the reference for the height of 0. However, as will be described later, for example, when the height of the valley bottom has swells at a period larger than the distance between adjacent protrusions of the microprojections, and the height of the valley bottom itself differs depending on the location, (1) First, The average value of the heights of the valley bottoms measured from the front surface or the back surface of the base material 2 is calculated within the area where the average value is sufficient for convergence. (2) Next, a surface having a height of the average value and parallel to the front surface or the back surface of the base material 2 is considered as a reference surface. (3) After that, the height of each microprojection from the reference plane is calculated by setting the reference plane to the height of 0 again.

When the protrusions are arranged irregularly, the maximum value dmax = d _AVG + 2σ of the distance between adjacent protrusions obtained in this way and the average value H _AVG of the heights of the protrusions are regularly arranged. It was found that it is necessary to satisfy the above conditions. Specifically, the condition of the distance between the microprojections that exhibits the antireflection effect is dmax ≦ Λmin. At a minimum, the minimum necessary condition that can exert the antireflection effect at the longest wavelength of the visible light band is Λmin = λmax, so dmax ≤ λmax, and the antireflection effect can be exerted for all wavelengths of the visible light band. Since the necessary and sufficient condition is Λmin = λmin, dmax ≦ λmin. A preferable condition for more reliably achieving the antireflection effect for all wavelengths in the visible light band is dmax ≦ 300 nm, and a more preferable condition is dmax ≦ 200 nm. Further, for the reason of exhibiting the antireflection effect and ensuring the isotropic property (low angle dependence) of the reflectance, dmax ≧ 50 nm is usually set, and dmax ≧ 100 nm is preferably set. 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-projection distance dave may be set to dave ≦ λmin.

Incidentally, when described by the examples of FIGS. 4 to 8, dmax = 234 nm ≦ λmax = 780 nm, and it can be seen that the antireflection effect can be sufficiently exhibited by satisfying the condition of dmax ≦ λmax. Further, 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 the entire wavelength band of visible light is also satisfied. Further, since dave ≦ dmax, it can be seen that the condition of dave ≦ λmin is also satisfied. Further, since the average protrusion height H _AVG = 178 nm, the average protrusion height H _AVG ≧ 0.2 × λmax = 156 nm (assuming the longest wavelength λmax = 780 nm in the visible light wavelength band), and a sufficient antireflection effect is realized. It can be seen that the conditions regarding the height of the protrusions for this 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 relating to the height of the protrusion (178 nm or more) is satisfied. From the observation results by AFM and SEM and the analysis result of the height distribution of the microprojections, the multimodal microprojections tend to occur more in the microprojections with higher height than in the microprojections with relatively low height. It has been found.

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

[Height distribution]
Here, the multimodal microprojections 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 related to the above-mentioned visible light region. There is.

FIG. 9 is a diagram showing an example of a frequency distribution of the height h of the microprojections formed on the antireflection article. As shown in FIG. 9, the mean 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 the middle altitude region and the region of m + σ <h is the high altitude region, the number of multimodal microprojections in each region is Nm and the total number of microprojections in the entire frequency distribution. It is prepared so that the ratio with 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 the medium altitude region> Nm / Nt in the high altitude region

FIG. 10 is a diagram showing a measurement result 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 thereof is σ = 22.1 nm. Here, in the frequency distribution of the height h of the microprojections, the low altitude region has h <m-σ = 123.6 nm, and the medium altitude region has m-σ = 123.6 nm ≦ h ≦ m + σ = 167.8 nm. Therefore, 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 the multimodal microprojections in the medium altitude region is 23, the Nm / Nt in the medium altitude region is 0.087. Since the number Nm of the multimodal microprojections in the low altitude region is two, the Nm / Nt in the low altitude region is 0.008. Since the number Nm of the multimodal microprojections in the high altitude region is 5, the Nm / Nt in the high altitude region is 0.019.

Therefore, the antireflection article of this embodiment has the relationship of (a) and (b) described above, that is,
(A) Nm / Nt = 0.087 in the medium altitude region> Nm / Nt = 0.008 in the low altitude region
(B) Nm / Nt = 0.087 in the medium altitude region> Nm / Nt = 0.019 in the high altitude region
To be satisfied.

Thus, the ratio (Nm / Nt) of the number of multimodal microprojections (Nm) in the medium-altitude region to the total number of microprojections (Nt) in the frequency distribution is larger than the ratio of the low-altitude region and the high-altitude region. By forming multimodal microprojections so as to be large, the reflectance for incident light in the visible light region can be reduced, and the antireflection function of the antireflection article can be widened.

In addition, in such a height distribution, this antireflection article also has a substantially average height of multimodal microprojections (two and three peaks are indicated by two peaks and three peaks, respectively). Since the normal distribution can be made to match, the viewing angle characteristics can be limited, rainbow unevenness due to optical interference can be suppressed, and a screen with low reflection and visually favorable for the viewer can be created. In addition, the scratch resistance of the multimodal microprojections can be efficiently improved.

Further, by adopting the above configuration, the antireflection article has a small ratio of multimodal microprojections distributed in high-height (180 nm or more) microprojections and a large proportion of monomodal microprojections. Even if another object makes frictional contact with the microprojections, the tall monomodal microprojections will come into contact first, and will come into contact with the multimodal microprojections that mainly improve the antireflection function. It can be suppressed from being stored.

It should be noted that the characteristics of these multimodal microprojections are unique characteristics of the multimodal microprojections produced by the microholes having the corresponding shapes of the molding die, and are unique to JP2012-307670. This is a feature that cannot be obtained by the multimodal microprojections caused by poor filling of the resin disclosed in the publication. That is, the multimodal microprojections due to poor resin filling are produced by not sufficiently filling the micropores originally produced as monomodal microprojections with resin, so that the distance between the vertices is large. It is extremely minute, and it is difficult to sufficiently improve the scratch resistance, and it is also difficult to improve the optical characteristics as described above.

In addition, the multimodal microprojections due to poor filling have poor reproducibility, which makes it impossible to mass-produce uniform products. On the other hand, the multimodal microprojections according to this embodiment have a drawback. High reproducibility can be ensured by the so-called mold. Further, as described in detail in the above-described embodiment, the height distribution of the multimodal microprojections can be controlled, whereas such control is difficult for the multimodal microprojections with poor filling. ..

〔Manufacturing process〕
FIG. 11 is a diagram showing a manufacturing process of the antireflection film 1. In this manufacturing step 10, in the resin supply step, an uncured and liquid acrylate-based ultraviolet curable resin constituting the receiving layer 4 is applied to the base material 2 in the form of a strip film by the die 11. It should be noted that various methods can be applied to the application of these coating liquids, not limited to the case of using the die 11. Subsequently, in this manufacturing step 10, the coating liquid related to the receiving layer 4 is leveled and dried. In this embodiment, in this leveling process, the side to which the coating liquid is applied is the upper side of the base material 2 so that the light diffusing particles 8 can be segregated by gravity to form the light diffusing layer 4B and the light transmitting layer 4A. The process is set so as to be, and the amount of solvent related to the coating liquid and the time of the leveling process are set. Subsequently, in this step, the base material 2 is pressed and pressed against the peripheral side surface of the roll plate 13, which is a mold for shaping the antireflection article, by the pressing roller 14, whereby the base material 2 is uncured and liquid. The ultraviolet curable resin is brought into close contact with the roll plate 13, and the fine uneven concave portions formed on the peripheral side surface of the roll plate 13 are sufficiently filled with the ultraviolet curable resin. In this manufacturing process, in this state, the ultraviolet curable resin is cured by irradiation with ultraviolet rays, whereby microprojections are produced on the surface of the base material 2. In this manufacturing step, the base material 2 is subsequently peeled from the roll plate 13 via the peeling roller 15 together with the cured ultraviolet curable resin. In the manufacturing step 10, an adhesive layer or the like is formed on the base material 2 as needed, and then cut into a desired size to produce an antireflection film 1. As a result, the antireflection film 1 is efficiently mass-produced by sequentially molding the fine shape formed on the peripheral side surface of the roll plate 13, which is a molding die, onto the long base material 2 made of a roll material. To. As shown by reference numeral B in FIG. 1, when the light diffusing layer 4B and the light transmitting layer 4A are manufactured by laminating, a step of applying a coating liquid is provided for each, and a curing step is added as necessary. Will be done. When the base material side intermediate holding layer is arranged, a step of applying the coating liquid related to the base material side intermediate holding layer and drying or curing is provided before the coating liquid is applied by the die 11. Be done. Further, when the easy-adhesion layer is provided, a step of forming the easy-adhesion layer on the base material 2 is provided in advance.

After the microprojections 5 are produced on one surface of the base material 2 in this manner, in the manufacturing process, the other surface of the base material 2 is saponified, and then the optical functional layer 106 and the base material 107 are sequentially provided. As a result, the base material 2 is also used and integrated with the linear polarizing plate.

[Roll plate manufacturing process]
FIG. 12 is a perspective view showing the configuration of the roll plate 13. In the roll plate 13, a fine uneven shape is formed on the peripheral side surface of the base material, which is a cylindrical metal material, by repeating anodizing treatment and etching treatment, and this fine uneven shape is formed on the base material 2. To. Therefore, in the roll plate 13, a cylindrical or cylindrical member provided with a high-purity aluminum layer on at least 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 metal, and the high-purity aluminum layer is provided by the curved shape corresponding to the envelope surface 9 at the valley bottom, either directly or through various intermediate layers. Provided. Instead of the stainless steel pipe, a pipe material such as copper or aluminum may be applied. 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 becomes larger as it approaches the opening. A concave-convex shape is created by gradually expanding the hole diameter of the fine holes. As a result, the roll plate 13 is densely formed with fine holes whose hole diameter gradually decreases in the depth direction, and the antireflection film 1 has a diameter gradually decreasing as it approaches the top corresponding to these fine holes. A fine uneven shape is produced by a large number of minute 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 metal is made into a super mirror surface by an electrolytic composite polishing method that combines an electrolytic elution action and an abrasion action by abrasive grains (electropolishing).

In the aluminum layer forming step, aluminum is sputtered on the peripheral side surface of the base material to prepare a high-purity aluminum layer. Subsequently, in this step, the base metal is processed by alternately repeating the anodizing steps A1, ..., AN, the etching steps E1, ..., EN to prepare the roll plate 13.

More specifically, in this manufacturing process, in the anodizing steps A1, ..., AN, fine holes are formed on the peripheral side surface of the base metal by the anodizing method, and the prepared fine holes are further dug. Here, in the anodizing step, various methods applied to anodizing aluminum can be widely applied, for example, when a carbon rod, a stainless plate material, or the like is used for the negative electrode. As the solution, various neutral and acidic solutions can be used, and more specifically, for example, a sulfuric acid aqueous solution, a oxalic acid aqueous solution, and a phosphoric acid aqueous solution can be used. In the manufacturing steps A1, ..., AN, by controlling the liquid temperature, the applied voltage, the time for anodizing, etc., the fine holes are made into the desired depth and the shape corresponding to the fine protrusion shape, respectively.

In the subsequent etching steps E1, ..., EN, the base material is immersed in an etching solution, and the hole diameters of the fine holes produced and dug by the anodic oxidation steps A1, ..., AN are enlarged by etching and directed toward the depth direction. These fine holes are shaped so that they are smooth and the hole diameter gradually decreases. As the etching solution, various etching solutions applied to this kind of treatment can be widely applied, and more specifically, for example, a sulfuric acid aqueous solution, an oxalic acid aqueous solution, a phosphoric acid aqueous solution and the like can be used. As a result, in this manufacturing process, the anodizing treatment and the etching treatment are alternately performed a plurality of times to prepare fine holes to be used for shaping on the peripheral side surface of the base material. The anodizing solution itself, such as the oxalic acid aqueous solution used in the anodizing process, functions as an etching solution when it is brought into contact with the base material without applying a voltage. Therefore, the anodic oxidation treatment liquid and the etching liquid are made the same liquid, and the anodic oxidation treatment is performed by sequentially applying a predetermined voltage for a predetermined time while the base material is immersed in the tank containing the same liquid, and no voltage is applied. It is also possible to perform the etching process by immersing in the above for a predetermined time.

[Details of anodizing and etching]
FIG. 14 is a diagram showing in detail the anodizing treatment and the etching treatment in FIG. 13 in the case where such monomodal microprojections and multimodal microprojections are mixed. Here, the applied voltage of the anodizing treatment and the pitch of the prepared fine holes are in a proportional relationship. However, in practice, the pitch of the fine holes varies depending on the grain boundaries of the aluminum used for the treatment. However, in FIG. 14, it will be described that there is no such variation and that the fine holes are produced in a regular arrangement. 14 (a) to 14 (e) are a plan view of the fine holes produced by each step and a corresponding cross-sectional view cut out along the line aa.

Here, first, in this embodiment, after performing the first anodizing treatment with a low applied voltage V1, an etching treatment (hereinafter, appropriately referred to as a first step) is performed, whereby FIG. 14 (a) shows. As shown, a fine hole f1 having a basic pitch related to this low applied voltage V1 is produced. Here, this first anodizing treatment creates a trigger for subsequent anodizing on the surface of the aluminum layer. In this case, the etching process of the first step may be omitted if necessary.

Subsequently, in this embodiment, the second anodizing treatment is executed at an applied voltage V2 (V2> V1) higher than that at the time of the first anodizing, and then the etching treatment is executed (hereinafter, appropriately referred to as a second step). ). Here, in this case, as shown in FIG. 14B, among the fine holes f1 produced by the first anodic oxidation treatment by increasing the applied voltage, the application related to the second anodic oxidation treatment is applied. Only the fine holes corresponding to the voltage are dug in the depth direction (indicated by reference numeral f2) and etched. As a result, by this second step, for example, if the applied voltage is changed in two steps, it is possible to mix fine holes having different depth distributions.

Subsequently, in this embodiment, the third anodizing treatment is executed at an applied voltage V3 (V3> V2) higher than that at the time of the second anodizing, and then the etching treatment is executed (hereinafter, appropriately referred to as a third step). ) (Fig. 14 (c)). Here, this 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 anodizing step. Here, if this increase in the applied voltage is performed discretely (stepwise), the height distribution of the microprojections can be set discretely, and microholes having different depth distributions can be mixed. Further, by continuously changing the increase in the applied voltage, the depth distribution can be set to a normal distribution.

Further, in this third step, the application time of the specific voltage related to anodic oxidation and the etching processing time are set longer than those in the first and second steps, whereby the first step and the first step are set as indicated by reference numeral f3. As if swallowing the fine holes f1 and f2 produced in the two steps, the fine holes f1 and f2 are combined to form a substantially flat microhole at the bottom.

Subsequently, in this embodiment, the fourth anodizing treatment is executed at an applied voltage V4 (V4> V3) higher than that at the time of the third anodizing, and then the etching treatment is executed (hereinafter, appropriately referred to as a fourth step). ) (Fig. 14 (d)). Here, the fourth step is a step for forming fine holes by a pitch according to a target inter-projection spacing, whereby 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 holes that were greatly dug in the third step is further dug, and the dug fine holes become monomodal microprojections. It becomes the corresponding fine hole f4.

Subsequently, in this embodiment, the fifth anodizing treatment is executed by the applied voltage V1 in the first step, and then the etching treatment is executed (FIG. 14 (e)). Here, in the fifth step, the fine holes whose bottom surface is made flat by the third step and which are not affected by the anodizing treatment in the fourth step have fine holes on the bottom surface. A plurality of microholes f5 for multi-peak projections 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.

Here, in this series of steps, the microholes f1 and f2 having different depths produced in the first and second steps are dug in the third step to produce microprojections f3 having a substantially flat bottom surface. In the fourth step, the microholes related to the unimodal microprojections are produced, and in the fifth step, the bottom surface of the microprojections f3 having a flat bottom surface is processed to produce the microholes related to the monomodal microprojections. By doing so, the applied voltage of the anodic oxidation treatment, the treatment time, the treatment time of the etching treatment, etc. related to the first to fourth steps are controlled to control the depth of the fine holes produced in each step. By doing so, the height distribution of the microprojections and the height distribution of the multimodal microprojections can be controlled. Needless to say, these first to fifth steps may be omitted, repeated, or integrated as necessary.

In this embodiment, the height distribution has the characteristics of the normal distribution as described above, so that the anodic oxidation step and the etching step are repeated 5 times, and the applied voltage of the first anodic oxidation step is V1. (It is a constant voltage in the range of 15V to 35V), and the applied voltages of the second, third, fourth, and fifth anodic oxidation steps were 2V1, 3.5V1, 5V1, and V1, respectively. The anodizing treatment was carried out for 100 seconds using an aqueous oxalic acid solution having a concentration of 0.02 M. In the etching step, an etching treatment was performed for 45 seconds using an aqueous oxalic acid solution having a concentration of 0.02 M, and then an etching treatment was performed for 110 seconds using an aqueous phosphoric acid solution having a concentration of 1.0 M.

According to the above configuration, by providing the light diffusion layer 4B on the base material 2 side of the intermediate holding layer, it is possible to prevent reflection due to internal reflection.

Further, the intermediate holding layer is composed of a shaping resin layer provided with light diffusing particles, so that the distance between the particles of the light diffusing particles is relatively short on the substrate side in this shaping resin layer. By forming a light-diffusing layer and forming a light-transmitting layer in which the distance between the light-diffusing particles is relatively long on the microprojection side, segregation of the light-diffusing particles mixed in the molding resin layer is performed. By laminating a light diffusing layer and a light transmitting layer made of the same or different resins, an intermediate holding layer can be produced, and reflection due to internal reflection can be further reduced as compared with the conventional case.

Further, by further providing an intermediate holding layer on the base material side between the light diffusion layer and the base material, various material layers capable of strengthening the adhesion between the base material and the molding resin layer are applied. As a result, the antireflection film can be formed to further reduce the reflection due to internal reflection as compared with the conventional case.

Further, by integrating such an antireflection film with the linear polarizing plate, the base material related to the microprojections can be shared with the base material related to the linear polarizing plate, and the configuration can be simplified.

[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 in 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, whereby the receiving layer 6 Instead, the base layer 7 functions as a light diffusing 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 relating to the light diffusion layer is different.

As a result, in the antireflection article 21, the particle size and the 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. The thickness is 1 μm or more and 30 μm or less so that the adhesion between 6 and the base material 2 can be sufficiently secured, and the base layer 7 functions sufficiently as a light diffusion layer to prevent reflection due to internal reflection. More preferably, it is produced by 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, the light diffusing particles are mixed in the base material side intermediate holding layer. Even if the light diffusion layer is formed, the same effect as that of the first embodiment can be obtained. Further, in this case, when the base material side intermediate holding layer is formed 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 formed. A light diffusing layer can be formed by mixing the light diffusing particles into the light diffusing particles.

Further, by forming the antireflection film in this way and integrating the antireflection film with the linear polarizing plate, the base material related to the microprojections can be shared with the base material related to the linear polarizing plate to simplify the configuration. Can be transformed into.

[Comparison results]
FIG. 16 is a chart showing the examination results of the examples. In FIG. 16, the comparative example is the 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 base material 2. Further, pentaerythritol triacrylate or isophorone diisocyanate was diluted with a solvent to prepare a coating liquid, and a base layer having a thickness of 1 μm was prepared by applying, drying and curing the coating liquid. Further, a mixture of polyethylene glycol diacrylate and pentaerythritol triacrylate at 70 wt% and 30 wt% or a mixture of polyethylene glycol diacrylate and hexamethylene diisocyanate at 70 wt% and 30 wt% is diluted with a solvent to make the silicone oil-based polymerizable. A coating liquid for the receiving layer related to the resin was prepared, and the coating liquid was coated, dried, and shaped to produce microprojections, whereby the receiving layer was prepared with a thickness of 40 to 50 μm.

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

Further, Examples 1, 2 and 3 are the configurations of the first embodiment described above, and in the configuration of Comparative Example 1, the light diffusing fine particles are mixed with the coating liquid of the receiving layer to form the light diffusing particles. This is a configuration in which a light diffusion layer is produced by segregation. In Examples 1 to 3, the weight ratios of the light diffusing particles and the resin in the coating liquid were set to 10%, 15%, and 20%, respectively, so that the haze values of only the light diffusing layer were 38.0 and 42. It was set to 0.0 and 59.0%. The haze value of only the light diffusion layer was measured by curing the receiving layer without any shaping treatment. The mixed light diffusing particles were made of an acrylic resin and had a particle size of 2 μm to 6 μm.

In the comparative example, a reflection with a sharp outline was observed due to internal reflection, and the deterioration of the quality of the display screen was perceived by this reflection. However, in Examples 1 to 3, even if the reflection cannot be completely prevented, the reflected object and its outline are observed to be blurred, whereby the deterioration of the quality due to the reflection is remarkably reduced. It was confirmed that. In FIG. 16, this evaluation is indicated by “small”.

The degree of blurring of the object and the contour can be adjusted by the difference in refractive index 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. .. If the haze value is too strong, the screen is observed to be whitish, but in the range of Examples 1 to 3, the reflection can be sufficiently reduced, and these Examples 1 to 3 are the most suitable. The configuration is different depending on the preference of the user, and the range of Examples 1 to 3 is a range depending on the user.

In the evaluation result according to FIG. 16, a sufficiently small value was obtained for the haze value, and a sufficiently large value was obtained for the transmittance, which was practically used. 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 the reflection of the front object due to the reflection on the outermost surface.

From these, it can be seen that the reflection can be sufficiently reduced according to these examples.

[Other Embodiments]
Although the specific configuration suitable for carrying out the present invention has been described in detail above, the present invention has variously modified the configurations of the above-described embodiments as long as the gist of the present invention is not deviated. Can be combined.

That is, in the above-described embodiment, the case where the base layer or the like is sequentially prepared on the base material has been described, but the present invention is not limited to this, and various preparation methods can be widely applied, for example, the base layer is formed by extrusion molding. The microprojections may be formed integrally with the material, and the light diffusing particles may be mixed with the resin material involved in this molding so that the base material itself functions as a light diffusing layer.

Further, in the above-described embodiment, the case where the antireflection article having a film shape is produced by the molding process using the roll plate has been described, but the present invention is not limited to this, and the transparent base material according to the shape of the antireflection article is used. Depending on the shape, for example, when an antireflection article is produced by processing a flat plate or a sheet using a molding die having a specific curved surface shape, the process related to the shaping process, the mold is an antireflection article. It can be appropriately changed according to the shape of the transparent base material according to the shape.

Further, in the above-described embodiment, the case where an acrylate-based ultraviolet curable resin is applied to the shaping resin has been described, but the present invention is not limited to this, and various ultraviolet curable resins such as epoxy-based and polyester-based resins, or Even when various materials such as electron beam curable resins such as acrylate, epoxy and polyester, thermosetting resins such as urethane, epoxy and polysiloxane, and various curing forms of shaping resins are used. It can be widely applied.

Further, in the above-described embodiment, as shown in FIG. 1, microprojection groups 5, 5A, 5B, ... Are formed only on one surface of the base material 2 (directly or via another layer). However, the present invention is not limited to such a form. The microprojection groups 5, 5A, 5B, ... May be formed on both sides of the base material 2 (directly or via another layer).
Further, although not shown, in the antireflection film 1 of the present invention as shown in FIG. 1 and the like, the surface of the base material 2 opposite to the surface on which the microprojection group is formed (the lower side surface of the base material 2 in FIG. 1). It is also possible to form an adhesive processed product in which various adhesive layers are formed on the surface of the adhesive layer, and a release film (release paper) is releasably laminated on the surface of the adhesive layer. In such a form, the release film can be peeled off to expose the adhesive layer, and the antireflection film 1 of the present invention can be laminated and laminated on a desired surface of a desired article by the adhesive layer. , It is possible to easily impart antireflection performance to a desired article. As the adhesive, various known adhesive forms such as an adhesive (pressure sensitive adhesive), a two-component curable adhesive, an ultraviolet curable adhesive, a heat curable adhesive, and a heat melting type adhesive can be used. ..

Further, although not shown, in the antireflection film 1 of the present invention as shown in FIG. 1 and the like, the microprojection groups 5, 5A, 5B, ... It is also possible to carry out transportation, sale, post-processing or construction, and then peel off and remove the protective film in a timely manner. In such a form, it is possible to prevent the microprojections from being damaged or contaminated during storage, transportation, etc., and the antireflection performance from being deteriorated.

Further, in the above-described embodiment, as shown in FIGS. 1 and 2A, the surface connecting the valley bottoms (minimum points of height) between the adjacent microprojections was a plane having a constant height. The present invention is not limited to this, and as shown in FIG. 17, the envelope surface connecting the valley bottoms between the microprojections has a period D (that is, D> λmax) of the longest wavelength λmax or more in the visible light band. May be configured. Further, the periodic swell has a constant height in only one direction (for example, the X direction) in the XY plane (see FIG. 2) parallel to the front and back surfaces of the base material 2 and in a direction orthogonal to this (for example, the Y direction). It may be present, or it may have undulations in both directions (X direction and Y direction) in the XY plane. By superimposing the uneven surface 9 undulating at the period D satisfying D> λmax on the microprojection group consisting of a large number of microprojections, the reflected light that cannot be completely prevented from being reflected by the microprojection group is scattered and remains. The reflected light, particularly the specularly reflected light, is made more difficult to see, and thus the antireflection effect can be further improved.

When the period D of the uneven surface 9 is not constant over the front surface and has a distribution, the frequency distribution of the distance between the convex portions is obtained for the uneven surface, the average value is _DAVG , and the standard deviation is Σ. When
D _MIN = D _AVG- 2Σ
Designed as an alternative to period D with the minimum distance between adjacent protrusions defined as. That is, the condition for sufficiently exerting the scattering effect of the residual reflected light of the microprojection group is
D _MIN > λmax
Is. Generally, D or D _MIN is 1 to 200 μm, preferably 10 to 100 μm.
The following is an example of a specific manufacturing method for forming a group of fine microprojections in which the envelope surface shape in which the valley bottoms of each microprojection are connected forms an uneven surface 9 having D (or D _MIN )> λmax. 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 the cylindrical (or columnar) -shaped base material by sandblasting or matte (matte) plating. Next, an appropriate intermediate layer is formed directly or if necessary on the uneven surface, and then an aluminum layer is laminated. After that, the aluminum layer having a surface shape corresponding to the uneven surface is subjected to anodizing treatment and etching treatment in the same manner as in the above-described embodiment to form a microprojection group including microprojections 5, 5A and 5B. To do.

Further, in the above-described embodiment, the case where the fine holes are formed by repeating the anodizing treatment and the etching treatment has been described, but the present invention is not limited to this, and the case where the fine holes are formed by applying the photolithography method. It can also be widely applied to.

Further, 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, but the present invention is not limited to this, and for example, a decorative film material arranged on the surface of a wall material, a furniture material, or the like. It can also be widely applied when it is placed on the surface of. In this case, in the cosmetic film material, by preventing reflection due to internal reflection, an extremely matte decorative film, a decorative film in which the wood grain pattern related to makeup is not impaired when viewed from various directions, etc. Can be provided.

Further, in the above-described embodiment, the case where the antireflection article having a film shape is arranged on the image display panel related to the antireflection film has been described, but the present invention is not limited to this, and can be applied to various uses. Specifically, it is applied to the application of placing on the back surface (image display panel side) of the front surface side member by a touch panel, various window materials, various optical filters, etc., which are installed on the screen of the image display panel through a gap. Can be done.

In addition, it should be placed on the front surface (outside world side) of the glass plate used for the show window and product display box of the store, the exhibition window and display box of the museum exhibit, or on both the front and back surfaces (side of the product or exhibit). You may. In this case, it is possible to improve the visibility of products, fine arts, etc. to customers and spectators by preventing light reflection on the surface of the glass plate.

It can also be widely applied to the surface of a lens or prism used in various optical devices such as eyeglasses, telescopes, cameras, video cameras, gun sights (sniper scopes), binoculars, and periscopes. In this case, visibility can be improved by preventing light reflection on the surface of the lens or prism. Further, it can be applied to the case of arranging it on the surface of a printed portion (characters, photographs, figures, etc.) of a book to prevent light reflection on the surface of the characters and improve the visibility of the characters and the like. In addition, place it on the surface of signboards, posters, and other various displays (direction guidance, maps, or non-smoking, entrances, emergency exits, off-limits, etc.) on various storefronts, streets, outer walls, etc. to improve their visibility. Can be done. Furthermore, the light entry surface of the window material (in some cases, also serves as a diffuser plate, condensing lens, optical filter, etc.) of a lighting fixture using an incandescent lamp, a light emitting diode, a light lamp, a mercury lamp, an EL (electric field emission), etc. By arranging it on the side, it is possible to prevent light reflection on the light entering surface of the window material, reduce the reflection loss of the light source light, and improve the light utilization efficiency. Further, it can be arranged on the display window surface (display observer side) of a clock or other various measuring instruments to prevent light reflection on the display window surface and improve visibility.

Furthermore, it is placed on the indoor side, outdoor side, or both sides of the window of the cockpit (driver's cab, wheelhouse) of vehicles such as automobiles, railroad vehicles, ships, and aircraft to prevent reflection of indoor and outdoor light in the window. As a result, the visibility of the outside world of the driver (driver, steering wheel) can be improved. Furthermore, by arranging it on the lens or window material surface of a night-vision device used for monitoring crime prevention, aiming a gun, astronomical observation, etc., visibility at night and in the dark can be improved.

Furthermore, the surface of transparent substrates (window glass, etc.) that make up windows, doors, partitions, walls, etc. of buildings such as houses, stores, offices, schools, and hospitals (indoor side, outdoor side, and both sides). It can be placed on the surface of the window to improve the visibility of the outside world or the lighting efficiency. Furthermore, it can be placed on the surface of a transparent sheet or a transparent plate (window material) of a greenhouse or an agricultural greenhouse to improve the efficiency of sunlight collection. Furthermore, it can be arranged on the surface of the solar cell to improve the utilization efficiency of sunlight (power generation efficiency).

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

Furthermore, in the above-described embodiment, the wavelength band of the electromagnetic wave for anti-reflection is exclusively the visible light band (entire or partial band), but the present invention is not limited to this, and the electromagnetic wave for anti-reflection is not limited to this. The wavelength band of may be set to a wavelength band other than visible light such as infrared rays and ultraviolet rays. In that case, in each of the above conditional expressions, the shortest wavelength Λmin in the wavelength band of the electromagnetic wave may be set to the shortest wavelength at which the antireflection effect in the wavelength band such as infrared rays and ultraviolet rays is desired. For example, when it is desired to prevent reflection in the infrared band having the shortest wavelength Λmin of 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, the antireflection effect cannot be expected in the visible light band (380 to 780 nm), and an antireflection article having an antireflection effect on infrared rays having a wavelength of 850 nm or more can be obtained.

In the various embodiments illustrated above, when the film-like antireflection article of the present invention is arranged on the front surface, the back surface, or both front and back surfaces of a transparent substrate such as a glass plate, the film-like antireflection article of the present invention is arranged and covered over the entire surface of the transparent substrate. Besides, it can be arranged only in a part of the area. As an example of this, for example, for one window glass, a film-like antireflection article is attached only to the indoor surface in a square area in the central portion thereof, and an antireflection article is attached to the other area. The case where it is not attached can be mentioned. In the case where the antireflection article is placed only in a part of the transparent substrate, the presence of the transparent substrate can be easily visually recognized by a person on the transparent substrate without installing a special display or a collision prevention fence. The effect of reducing the risk of collision and injury, and the effect of preventing peeping indoors (indoors) and the transparency of the transparent substrate (in the area where the antireflection article is arranged) can be achieved at the same time.

1,21 Anti-reflective article 2,107,108 Base material 4,6 Intermediate holding layer, receiving layer (resin layer for shaping)
5, 5A, 5B Microprojection 5X Microprojection layer 7 Underlayer 8 Light diffusing 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 (8)

In an antireflection article in which the microprojections are closely arranged and the distance between the adjacent microprojections is equal to or less than the shortest wavelength of the wavelength band of the electromagnetic wave for antireflection.
The microprojections
It is held on the surface of the base material by the transparent film material via the intermediate holding layer,
It is composed of multimodal microprojections with multiple vertices and monomodal microprojections with one vertex.
The intermediate holding layer
It is a laminate of the base material side intermediate holding layer and the microprojection side intermediate holding layer.
The intermediate holding layer on the base material side is mixed with light diffusing particles to form a light diffusing layer .
The light diffusing particles have a particle size of 2 μm or more and 10 μm or less.
The light diffusing particles are added in an amount of 20% or more and 50% or less by weight with respect to the light diffusing layer.
The light diffusion layer has a thickness of 5 μm or more and 50 μm or less.
The antireflection article formed such that the intermediate holding layer on the microprojection side does not contain the light diffusing particles. Let h be the height of the microprojections, m be the mean value in the frequency distribution of this height h, and σ be the standard deviation.
The region of h <m-σ is defined as the low altitude region.
The region of m-σ ≤ h ≤ m + σ is defined as the medium altitude region.
The region of m + σ <h is defined as the high altitude region.
The ratio of the number Nm of the multimodal microprojections in each region to the total number Nt of the microprojections in the entire frequency distribution is
Nm / Nt in the middle altitude region> Nm / Nt in the low altitude region, and
Nm / Nt in the medium altitude region> Nm / Nt in the high altitude region
To satisfy the relationship,
The antireflection article according to claim 1. The ratio of the number of multimodal microprojections to the total number of microprojections is 10% or more.
The antireflection article according to claim 1 or 2. The ratio of the number of multimodal microprojections to the total number of microprojections is 90% or less.
The antireflection article according to any one of claims 1 to 3, wherein the antireflection article is characterized. The amount of the light diffusing particles added to the light diffusing layer shall be 20% or more and 50% or less by weight with respect to the light diffusing layer.
The antireflection article according to any one of claims 1 to 4, wherein the antireflection article is characterized. Haze value is 10 or more and 50 or less
The antireflection article according to any one of claims 1 to 5, wherein the antireflection article is characterized. An antireflection article in which the antireflection article according to any one of claims 1 to 6 is laminated and integrated with a linear polarizing plate. An image display device in which the antireflection article according to any one of claims 1 to 6 is arranged on a panel surface of an image display panel.