JP5261598B1 - Antireflection article, image display device, and mold for manufacturing antireflection article - Google Patents

Abstract

An anti-reflection article having a moth-eye structure is improved in scratch resistance.
In the antireflection article 1 in which microprotrusions are closely arranged and the interval between adjacent microprotrusions is equal to or less than the shortest wavelength of the wavelength band of electromagnetic waves to prevent reflection, a part of the microprotrusions is A convex projection group 5 comprising a top microprojection 51 and a plurality of peripheral microprojections 52 formed around the top microprojection 51 and having a height higher than the top microprojection 51 is configured. It is set as the anti-reflective article 1 which is.
[Selection] Figure 10

Description

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

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

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

  By the way, the antireflection article according to this kind of moth-eye structure has a problem that the scratch resistance is still insufficient in practice. That is, for example, when an anti-reflective article is brought into contact with another object, the anti-reflective function is locally deteriorated, and a white turbidity, a flaw or the like is generated at the contact portion, resulting in poor appearance.

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

  The present invention has been made in view of such a situation, and an object of the present invention is to improve the scratch resistance of an antireflection article having a moth-eye structure as compared with the conventional art.

  The present inventor has conducted extensive research to solve the above-described problems, and is formed with one top microprojection and a periphery of the top microprojection, and a plurality of heights lower than the top microprojection. The idea of providing a convex projection group consisting of peripheral peripheral projections was completed, and the present invention was completed. In the following, a microprotrusion having only one apex with respect to the same collar as shown in FIG. 10 is referred to as a single-peak microprotrusion. On the other hand, a microprotrusion having two or more vertices with respect to the same heel as shown in FIG. 11 is called a multimodal microprotrusion. Moreover, each convex part which forms each vertex which concerns on a multimodal microprotrusion and a monomodal microprotrusion is called a peak suitably.

    Specifically, the present invention provides the following.

(1) In an antireflection article in which microprotrusions are closely arranged, and an interval between the adjacent microprotrusions is equal to or less than the shortest wavelength of the wavelength band of electromagnetic waves for antireflection,
At least a part of the microprotrusions includes one top microprojection and a plurality of peripheral microprojections formed adjacent to the periphery of the top microprotrusion and having a height lower than that of the top microprotrusion. Convex projections are formed.

  According to (1), a plurality of peripheral micro-projections having a lower height are provided adjacent to the periphery of one top micro-projection to form a convex projection group. When an impact force is applied due to contact or the like, the top microprotrusions absorb the impact in a concentrated manner, so that a plurality of adjacent peripheral microprotrusions can be prevented from being damaged by the impact. Total loss can be prevented. Thereby, local deterioration of the antireflection function can be reduced, and the occurrence of appearance defects can be further reduced.

  (2) In (1), the fine projections constituting one convex projection group vary in height within a standard deviation range of 10 nm or more and 50 nm or less.

  According to (2), it is possible to more reliably avoid contact of peripheral minute protrusions with various member surfaces. Thereby, it is possible to prevent the entire loss of the fine protrusions within a certain range more reliably.

  (3) In (1) or (2), the plurality of peripheral microprojections are reduced in height as they move away from the top microprojections.

  According to (3), the convex-shaped projection group consisting of a plurality of micro-projections exhibits the operational effect equivalent to a single micro-projection in the so-called moth-eye structure as a whole. As a result, it is possible to obtain a sufficient antireflection effect while reducing local deterioration of the antireflection function and occurrence of poor appearance as compared with the case where only substantially uniform microprojections exist.

  (4) In any one of (1) to (3), it is a part of a curved surface including each vertex of the microprotrusions and becomes wider from the apex of the top microprotrusions toward the lower end. In the envelope surface of the convex protrusion group which is a bell-shaped curved surface, the maximum distance between the lower end portions of the envelope surface is 780 nm or less.

  According to (4), the convex-shaped protrusion group which consists of a some microprotrusion acts similarly to the single microprotrusion which comprises a moth-eye structure as the whole group, and can show | play an antireflection effect.

  (5) In (4), the maximum distance between the lower end portions is 380 nm or less.

  According to (5), the convex projection group composed of a plurality of micro-projections acts as a single micro-projection constituting the moth-eye structure as a whole, and for all wavelengths of light in the visible light band. Can exhibit an antireflection effect.

(6) In any one of (1) to (5), at least a part of the microprojections is
It is a minute projection having a plurality of vertices.

  According to (6), by providing a microprotrusion with superior mechanical strength compared to a unimodal microprotrusion, when an impact force is applied, compared to the case of only a unimodal microprotrusion. Thus, it is possible to prevent the protrusions from being damaged, thereby reducing local deterioration of the antireflection function and further reducing the appearance defects. Further, even if the microprojection is damaged, the area of the damaged portion can be reduced. This can also reduce the local deterioration of the antireflection function and further reduce the appearance failure.

  (7) In any one of (1) to (6), a ratio of the minute protrusions constituting the convex protrusion group among the minute protrusions is 10% or more.

  According to (7), the effect of reducing the local deterioration of the antireflection function and the occurrence of poor appearance due to the provision of the convex protrusion group described above is more stably expressed.

  (8) In the image display device, the antireflection article according to any one of (1) to (7) is disposed on the light exit surface of the image display panel.

  According to (8), it is possible to provide an image display device using an antireflection article with improved scratch resistance.

(9) A mold for manufacturing an antireflection article for use in manufacturing an antireflection article,
The antireflective article is
The microprotrusions are closely placed,
The interval between the adjacent minute protrusions is equal to or less than the shortest wavelength of the wavelength band of the electromagnetic wave for preventing reflection,
A convex shape comprising a part of the microprotrusions and a plurality of peripheral microprotrusions formed adjacent to the periphery of the top microprotrusions and having a height lower than that of the top microprotrusions. A group of protrusions,
The mold for manufacturing the antireflection article is:
Micropores corresponding to the microprotrusions were produced in close contact.

  According to (9), in the anti-reflective article manufactured with the mold, the convex projection group is provided on the anti-reflective article. It is possible to prevent the protrusions from being damaged, thereby reducing local deterioration of the antireflection function and further reducing the occurrence of poor appearance. This can also reduce local deterioration of the antireflection function and further reduce the occurrence of poor appearance.

  With respect to the antireflection article according to the moth-eye structure, it is possible to improve the scratch resistance as compared with the conventional art.

1 is a conceptual perspective view showing an antireflection article according to a first embodiment of the present invention. It is a figure where it uses for description of an adjacent protrusion. It is a figure where it uses for description of the maximum point. It is a figure which shows a Delaunay figure. It is a frequency distribution diagram used for measurement of the distance between adjacent protrusions. It is a frequency distribution figure with which it uses for description of minute height. It is a figure which shows the manufacturing process of the antireflection article | item of FIG. It is a figure which shows the roll plate which concerns on the reflection preventing article of FIG. It is a figure which shows the preparation process of the roll plate of FIG. It is a figure where it uses for description of a microprotrusion and a convex-shaped protrusion group. It is a figure where it uses for description of the microprotrusion which has multiple apexes. It is a figure which shows the AFM cross-sectional profile of a microprotrusion and a convex microprotrusion group. It is a conceptual sectional view showing the form in which the envelope surface of the valley bottom of the microprojection exhibits an uneven surface (waviness).

[First Embodiment]
FIG. 1 is a diagram (conceptual perspective view) showing an antireflection article according to a first embodiment of the present invention. This antireflection article 1 is an antireflection film whose overall shape is formed by a film shape. In the image display apparatus according to this embodiment, the antireflection article 1 is held by being attached to the front side surface of the image display panel, and the reflection of external light such as sunlight and electric light on the screen is reduced by the antireflection article 1. And improve visibility. The anti-reflective article is not limited to a flat film shape, but may be a flat sheet shape or a flat plate shape (referred to as a film, a sheet, or a plate in the order of relatively thin thickness). Also, instead of a flat shape, a curved shape, a three-dimensional film shape, a sheet shape, or a plate shape can be used, and various types of lenses, prisms, and other three-dimensional shapes can be used depending on the application. Can be adopted as appropriate.

  Here, the antireflection article 1 is produced by closely arranging a large number of minute protrusions on the surface of the substrate 2 made of a transparent film. In the present specification, a plurality of closely arranged microprotrusions are collectively referred to as a microprotrusion group. Here, the base material 2 is, for example, cellulose resin such as TAC (Triacetyl cellulose), acrylic resin such as PMMA (polymethyl methacrylate), polyester resin such as PET (Polyethylene terephthalate), PP (polypropylene), and the like. Polyolefin resins such as PVC, vinyl resins such as PVC (polyvinyl chloride), and various transparent resin films such as PC (Polycarbonate) can be applied. As described above, the shape of the antireflection article is not limited to the film shape, and various shapes can be adopted, so that the base material 2 can be used in addition to these materials according to the shape of the antireflection article. For example, glass such as soda glass, potash glass, lead glass, ceramics such as PLZT, various transparent inorganic materials such as quartz, meteorite, and the like can be applied.

  The antireflective article 1 is a layer made of an uncured ultraviolet curable resin (hereinafter referred to as an ultraviolet curable resin layer 4, Alternatively, the receiving layer 4 is formed, and the receiving layer 4 is cured in a state in which the shaping surface of the shaping mold is in contact with the surface of the receiving layer 4, thereby forming microprojections on the surface of the substrate 2. Are closely arranged. The antireflection article 1 is manufactured so that the refractive index gradually changes in the thickness direction due to the uneven shape by the microprotrusions, and reduces the reflection of incident light in a wide wavelength range by the principle of the moth-eye structure.

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

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

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

  However, when the minute protrusions are irregularly arranged as in the antireflection article of the present invention, the distance d between adjacent minute protrusions varies. More specifically, as shown in FIG. 2, when viewed from the normal direction of the front surface or back surface of the substrate, when the smile protrusions are not regularly arranged at a constant period, the repetition period P of the protrusions In some cases, the distance d between adjacent protrusions cannot be defined, and even the concept of adjacent protrusions is suspicious. In such a case, the distance d between the microprojections is calculated as follows.

  (1) That is, first, an in-plane arrangement of projections (planar shape of the projection array) is detected using an atomic force microscope (AFM) or a scanning electron microscope (SEM). FIG. 2 is an enlarged photograph actually obtained by an atomic force microscope.

  (2) Subsequently, the maximum point of the height of each protrusion (hereinafter, also simply referred to as “maximum point”) is detected from the obtained in-plane arrangement. In addition, as a method for obtaining the maximum point, there are various methods such as a method for obtaining a local maximum point by sequentially comparing a planar view shape and a corresponding magnified photograph of a ridge surface, a method for obtaining a local maximum point by image processing of a planar view enlarged photograph, and the like. Can be applied. FIG. 3 is a diagram showing the detection result of the maximum point by the processing of the image data relating to the enlarged photograph shown in FIG. 2, and the portions indicated by black dots in this figure are the maximum points of the respective protrusions. In this process, image data is processed in advance by a low-pass filter based on a Gaussian characteristic of 4.5 × 4.5 pixels, thereby preventing erroneous detection of the 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 of 8 pixels × 8 pixels.

  (3) Next, a Delaunay diagram with the detected maximum point as a generating point is created. Here, Delaunay diagram is obtained by dividing the Voronoi region adjacent to the Voronoi region when the Voronoi division is performed with each local maximum as the generating point, and connecting the adjacent generating points with line segments. This is a net-like figure made up of triangular aggregates. Each triangle is called a Delaunay triangle, and a side of each triangle (a line segment connecting adjacent generating points) is called a Delaunay line. FIG. 4 is a diagram in which the Delaunay diagram (represented by white line segments) obtained from FIG. 3 is superimposed on the original image of FIG. The Delaunay diagram has a dual relationship with the Voronoi diagram. Voronoi division means that a plane is divided by a net-like figure composed of a closed polygon aggregate defined by perpendicular bisectors of line segments (Droney lines) connecting adjacent neighboring points. . A network figure obtained by Voronoi division is a Voronoi diagram, and each closed region is a Voronoi region.

  (4) Next, the frequency distribution of the line segment length of each Delaunay line, that is, the frequency distribution of the distance between adjacent maximum points (hereinafter also referred to as “distance between adjacent protrusions”) is obtained. FIG. 5 is a histogram of the frequency distribution created from the Delaunay diagram of FIG. In addition, as shown in FIG. 2, FIG. 10 and FIG. 11, when a concave portion such as a groove exists at the top of the projection, or when the top is divided into a plurality of peaks, from the obtained frequency distribution, Such a fine structure having a concave portion at the top of the protrusion and data resulting from a fine structure in which the top is split into a plurality of peaks are removed, and only the data of the protrusion itself is selected to create a frequency distribution.

  Specifically, in a microstructure having a concave portion at the top of the projection, or a microstructure having a multi-peak microprojection in which the top is split into a plurality of peaks, a single peak that does not have such a microstructure The distance between adjacent local maximum points is clearly different from the numerical value range in the case of a sexual microprojection. Thus, by removing the corresponding data using this feature, only the data of the projection body itself is selected and the frequency distribution is detected. More specifically, for example, about 5 to 20 adjacent single-peaked microprojections are selected from a magnified photograph of a microprojection (group) in plan view as shown in FIG. The distance value is sampled, and the value clearly deviates from the numerical range obtained by sampling (usually, the value is 1/2 or less of the average distance between adjacent maximum points obtained by sampling) Data) is excluded and the frequency distribution is detected. In the example of FIG. 5, data having a distance between adjacent maximal points of 56 nm or less (the leftmost small mountain indicated by the arrow A) is excluded. FIG. 5 shows a frequency distribution before such exclusion processing is performed. Incidentally, such exclusion processing may be executed by setting the above-described maximum inspection filter.

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

The height of the protrusion is defined by applying a similar method. In this case, the relative height difference of each local maximum point position from a specific reference position is acquired from the local maximum point obtained by the above (2), and is histogrammed. FIG. 6 is a diagram showing a histogram of the frequency distribution of the protrusion height H with the protrusion root position obtained in this way as a reference (height 0). The average value _HAVG of the protrusion height and the standard deviation σ are obtained from the frequency distribution based on the histogram. Here in the example of FIG. 6, 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 projection height H shown in FIG. 6, in the case of a multi-peak microprojection, the plurality of data are mixed for one projection because of having a plurality of vertices. . Therefore, in this case, the frequency distribution is obtained by adopting the highest vertex from among the plurality of vertices where the collar portion is heeled on the same minute projection as the projection height of the minute projection.

  In addition, the reference position when measuring the height of the projection described above is based on a valley bottom (minimum height) between adjacent minute projections as a reference for height 0. However, when the height of the valley bottom itself varies depending on the location (for example, as described later with reference to FIG. 12, the height of the valley bottom has undulation with a period larger than the distance between adjacent projections of the microprojections). (1) First, the average value of the height of each valley bottom measured from the front surface or the back surface of the substrate 2 is calculated within an area sufficient for the average value to converge. (2) Next, a surface having the height of the average value and parallel to the front surface or the back surface of the substrate 2 is considered as a reference surface. (3) Then, the height of each microprotrusion from the reference surface is calculated by setting the reference surface to a height of 0 again.

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

2 to 6, dmax = 232 nm ≦ λmax = 780 nm, and it can be seen that the antireflection effect can be sufficiently achieved by satisfying the condition of dmax ≦ λmax. In addition, since the shortest wavelength λmin in the visible light band is 380 nm, it can be seen that the sufficient condition dmax ≦ λmin for expressing the antireflection effect in all the visible light wavelength bands is also satisfied. Moreover, the average projection the height _H AVG = 178 nm, the average projection height HAVG ≧ 0.2 × λmax = 156nm becomes (as the longest wavelength .lambda.max = 780 nm in the visible light wavelength band), realizing a sufficient antireflection effect It can be seen that the conditions regarding the height of the protrusions to satisfy are also satisfied. Incidentally, 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 However, it turns out that the conditions (178 nm or more) concerning the height of protrusion are satisfied. In addition, from the observation result by AFM and SEM and the analysis result of the height distribution of the microprojections, the multi-peak microprojections tend to be generated more frequently with the high microprojections than the relatively low microprojections. Turned out to be.

  FIG. 7 is a diagram illustrating a manufacturing process of the antireflection article 1. In the manufacturing process 10, in the resin supplying process, an uncured and liquid ultraviolet curable resin that forms the microprojection-shaped receiving layer 4 is applied to the base material 2 in the form of a strip by the die 12. In addition, about application | coating of an ultraviolet curable resin, not only the case by the die | dye 12 but various methods are applicable. Subsequently, in this manufacturing process 10, the substrate 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 substrate 2 is uncured and liquid. The acrylate-based ultraviolet curable resin is closely attached, and the ultraviolet curable resin is sufficiently filled in the concave portions having a minute uneven shape formed on the peripheral side surface of the roll plate 13. In this state, in this manufacturing process, the ultraviolet curable resin is cured by irradiation with ultraviolet rays, and thereby a microprojection group is produced on the surface of the substrate 2. In this manufacturing process, the substrate 2 is peeled off from the roll plate 13 through the peeling roller 15 together with the cured ultraviolet curable resin. In the production process 10, an anti-reflection article 1 is produced by producing an adhesive layer or the like on the substrate 2 as necessary, and then cutting it into a desired size. As a result, the antireflection article 1 is mass-produced efficiently by sequentially molding the minute shape produced on the peripheral side surface of the roll plate 13 which is a mold for molding on the long base material 2 made of a roll material. The

  FIG. 8 is a perspective view showing the configuration of the roll plate 13. The roll plate 13 is formed with a minute uneven shape on the peripheral side surface of the base material, which is a cylindrical metal material, by repeating anodization treatment and etching treatment, and the minute uneven shape is the base material 2 as described above. It is shaped. For this reason, a columnar or cylindrical member in which a high-purity aluminum layer is provided at least on the peripheral side surface is used as the base material. More specifically, in this embodiment, a hollow stainless steel pipe is applied to the base material, and a high-purity aluminum layer is provided directly or via various intermediate layers. In addition, it may replace with a stainless steel pipe and may apply pipe materials, such as copper and aluminum. The roll plate 13 is formed such that minute holes are densely formed on the peripheral side surface of the base material by repeating the anodizing process and the etching process, and the diameter of the roll plate 13 is increased as it approaches the opening. The concavo-convex shape is produced by gradually expanding the diameter of the minute holes. As a result, the roll plate 13 is formed with a large number of minute holes whose hole diameter gradually decreases in the depth direction, and the antireflection article 1 has a diameter gradually corresponding to the minute hole as it approaches the top. A minute concavo-convex shape is produced by a small protrusion with a small. At that time, by appropriately adjusting the purity (amount of impurities), crystal grain size, anodizing treatment and / or etching treatment conditions of the aluminum layer, the shape of the fine protrusion unique to the present invention is obtained.

[Anodic oxidation treatment, etching treatment]
FIG. 9 is a diagram illustrating a manufacturing process of the roll plate 13. In this manufacturing process, the peripheral side surface of the base material is made into a super mirror surface by an electrolytic composite polishing method that combines electrolytic elution action and abrasion action by abrasive grains (electrolytic polishing). Subsequently, in this step, aluminum is sputtered on the peripheral side surface of the base material to produce a high-purity aluminum layer. Subsequently, in this process, the base material is processed by alternately repeating the anodic oxidation processes A1,..., AN, and the etching processes E1,.

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

  In the subsequent etching step E1,..., EN, the mold is immersed in an etching solution, the hole diameter of the minute hole produced and dug in the anodizing step A1,. These minute holes are shaped so that the hole diameter becomes smaller and smoother. As the etching solution, various etching solutions applied to this type of treatment can be widely applied. More specifically, for example, an aqueous sulfuric acid solution, an aqueous oxalic acid solution, an aqueous phosphoric acid solution, or the like can be used. . Accordingly, in this manufacturing process, the anodizing process and the etching process are alternately performed a plurality of times, thereby forming micro holes for shaping on the peripheral side surface of the base material.

[Improved scratch resistance]
By the way, when an antireflection article was produced by producing minute holes by alternately repeating this anodizing treatment and etching treatment, there was room for improvement in scratch resistance as described above. Therefore, when the antireflection article was observed in detail, it consisted of only single-peaked microprojections having only one apex, such as a polygonal pyramid shape and a rotating paraboloid shape, as in this type of conventional antireflection article. If the height of each vertex is also made uniform, for example, when another object comes into contact, the shape of the microprojections is uniformly damaged over a wide range, thereby locally preventing the antireflection function. It was found that the appearance deteriorated due to deterioration and white turbidity, scratches and the like at the contact points. However, it has been found that such scratch resistance is improved by changing the production conditions of the roll plate.

  When the surface shape of such an antireflection article with improved scratch resistance was observed with an AFM (Atomic Force Microscope) and an SEM (Scanning Electron Microscope: scanning electron microscope), a number of microprojections were observed. A plurality of peripheral microprojections having a relatively low height are formed around a part of the top microprojection having a relatively high height, and the plurality of peripheral microprojections are formed on the top portion. As the distance from the microprotrusions is increased, the heights are gradually decreased, and it has been found that a group of convex protrusions is formed as a whole. Although various types of microscopes are provided here for observing the minute shape, AFM and SEM are suitable for observing the surface shape of the antireflection article without damaging the microstructure. ing.

  Here, as described above, the height of each microprotrusion is the height of the peak (highest peak) having the highest height at the top of a specific microprotrusion that shares the ridge (base) portion. Say. In the case of a single-peak microprojection such as 51 and 52 in FIG. 10A, the height of the only peak (maximum point) at the top is the projection height of the microprojection. Further, in the case of a multi-peaked microprojection such as the microprojection 51B of FIG. 11, the height of the microprojection is defined as the height of the highest peak among a plurality of peaks sharing the ridge at the top.

  In the antireflection article 1, a part of the microprojections constitutes a group of convex projections 5, which will be described in detail below, as a group including a plurality of microprojections having different heights (FIG. 10A, FIG. 10 (b) and FIG. 10 (c)). FIG. 10 is a sectional view (FIG. 10), a perspective view (FIG. 10 (b)), and a plan view (FIG. 10 (c)) for explaining a convex protrusion group constituted by a plurality of minute protrusions. Note that FIG. 10 is a diagram schematically showing for easy understanding, and FIG. 10A shows the vertices of the continuous minute projections, a part of which constitutes the convex projection group 5. It is a figure which takes and shows a cross section by the broken line to connect. 10B and 10C, the xy direction is the in-plane direction of the base material 2, and the z direction is the height direction of the microprojections.

  The convex protrusion group 5 is a group of micro protrusions in which a plurality of peripheral micro protrusions 52 having relatively low heights are arranged around the one top micro protrusion 51 having a relatively high height. Shall be said. (Hereinafter, the top microprojections 51 and the peripheral microprojections 52 are also simply referred to as “microprojections”.) The convex projection group 5 has a plurality of peripheral microprojections as they move away from the top microprojections. It is preferable that they are arranged so that the height decreases sequentially.

  Thus, in the convex projection group 5 constituted by a plurality of microprojections having different heights, for example, even when the shape of the top microprojection 51 having a high height is damaged by contact with an object, the height The shape of the low peripheral microprojections 52 is maintained. Since the convex projection group 5 is configured as described above, the antireflection article can reduce the local deterioration of the antireflection function and further reduce the occurrence of appearance defects. Abrasion property can be improved.

  Further, when dust adheres between the minute protrusions on the surface of the antireflection article 1 and another object, the dust functions as an abrasive when the object slides relative to the antireflection article. As a result, wear and damage of the microprotrusions are promoted. In this case, on the surface of the antireflective article 1 where the convex protrusion group 5 is configured, the dust strongly contacts the high top microprojections 51 and damages them. On the other hand, the contact with the peripheral microprotrusions 52 having a low height is weakened, and the peripheral microprotrusions 52 having a low height are reduced in damage, and the antireflection performance is maintained by the peripheral microprotrusions 52 remaining intact or lightly. The

  Further, in the convex projection group 5, only the top minute projections 51 come into contact with various member surfaces arranged so as to face the antireflection article 1, for example. Thereby, it is possible to remarkably improve the slip as compared with the case where only the minute protrusions having the same height are used, and it is possible to easily handle the antireflection article in the manufacturing process or the like. From the viewpoint of improving the slipping as described above, the variation needs to be 10 nm or more when defined by the standard deviation. However, when the variation is larger than 50 nm, a feeling of surface roughness due to the variation can be felt. Therefore, the height variation is preferably 10 nm or more and 50 nm or less.

  Further, in the convex protrusion group 5, when the peripheral microprotrusions 52 become lower in height as they move away from the top microprotrusions 51, more preferably, as shown in FIG. The envelope surface of the convex projection group 5 which is configured to include the apexes (P1, P2,...) And is wide from the apex (P1) to the lower end (r0) of the top microprojection 51 has a bell shape. In the case of a curved surface, the convex projection group 5 can exhibit the same function and effect as the whole group as a single microprojection in a so-called moth-eye structure. Therefore, the antireflection article 1 including the convex protrusion group 5 exhibits the effect of improving the scratch resistance described above, and is equivalent to or more than when only a single minute protrusion is present. The antireflection effect can be exhibited.

  Here, the envelope surface of the convex projection group 5 is a part of a free-form surface created by a Bezier curve (or B-spline curve) or the like including each local maximum point of the fine projection of the antireflection article 1. The curved surface formed in the part which reaches the other lower end part r0 through the vertex (P1) of the top microprotrusion 51 from the lower end part r0 of the curve. Further, the maximum value of the distances between a plurality of r0 on one envelope surface is defined as the width W of the convex projection group 5.

  Then, when the width W of the convex protrusion group 5 is 780 nm or less, as described above, as in the case where the distance d between adjacent protrusions between the single minute protrusions is λmax (780 nm) or less. The convex protrusion group 5 can contribute to the improvement of the antireflection effect at the maximum wavelength in the visible light band. Moreover, if the width W of the convex protrusion group 5 is 380 nm or less, it can contribute to the improvement of the antireflection effect with respect to light of all wavelengths in the visible light band.

  In addition to the above effects, when there is a distribution (height difference) in the height of each microprotrusion between the microprotrusions on the surface of the antireflection article 1, the antireflection performance is broadened, such as white light. It is advantageous for realizing a low reflectivity in the entire spectrum band with respect to light in which multiple wavelengths are mixed or light having a broad spectrum. This is because the wavelength band of electromagnetic waves that can exhibit good antireflection performance by such a group of minute protrusions depends on the protrusion height in addition to the distance d between adjacent protrusions.

  Although the convex protrusion group 5 can improve the scratch resistance due to the presence thereof, it is needless to say that the effect of improving the scratch resistance cannot be sufficiently exhibited when it does not exist sufficiently. From such a point of view, in the present invention, the proportion of the microprojections constituting the convex projection group 5 out of the microprojections existing on the surface (hereinafter, this ratio is also referred to as “convex projection group constituent ratio”) is 10%. That's it. In particular, in order to sufficiently exhibit the effect of improving the scratch resistance by the convex protrusion group 5, the convex protrusion group constituent ratio is set to 30% or more, preferably 50% or more.

On the other hand, when the individual microprotrusions were examined in more detail, in the antireflection article 1, many microprotrusions gradually increased in cross-sectional area (surface perpendicular to the height direction (see FIG. 10 is a single-peak microprojection having only one apex, which is a single-peak microprojection having a single apex, as shown in FIGS. 2 and 11. As described above, there were also multi-peak microprojections in which a groove was formed at the tip portion and the apex of the microprojection consisting of the same collar portion was divided into a plurality of portions as if a plurality of microprojections were combined. Specifically, the two vertices of the microprotrusions made of the same buttock are two (see two microprotrusions for the maximum point (black dot) in FIG. 3), and the vertices are three (see FIG. 3). 11 (see 51B)), and those having four or more vertices (not shown). Note that the shape of the unimodal microprotrusions can be approximated by a round shape at the top, such as a paraboloid of revolution, or a pointed shape, such as a cone. On the other hand, the shape of the multimodal microprotrusions is approximately approximated by a shape in which a groove-shaped recess is cut in the vicinity of the top of the single-peak microprotrusions and the top is divided into a plurality of peaks. The shape of the multi-peaked microprojection, or the vertical cross-sectional shape when cutting along a virtual cut surface including a plurality of peaks and including the height direction (Z-axis direction in FIG. 11) includes a plurality of maximum points. The shape is approximated by an algebraic curve Z = a ₂ X ² + a ₄ X ⁴ +... + A _2n X ²ⁿ +.

In such multi-peak microprojections having a plurality of vertices, the thickness of the skirt portion relative to the size in the vicinity of the vertices is relatively thicker than that of a single-peak microprojection. Thereby, it can be said that the multimodal microprotrusions are superior in mechanical strength to the single-peak microprotrusions. Thus, when there are multi-peaked microprojections having a plurality of vertices, it is considered that the anti-reflective article has improved scratch resistance as compared with the case of using only single-peak microprojections. Furthermore, when an external force is applied to the antireflection article, the external force is distributed and received at more vertices than when only a single-peaked microprojection is used. Thus, it is possible to make it difficult for the microprotrusions to be damaged, thereby reducing the local deterioration of the antireflection function and further reducing the appearance defects. Moreover, even if a microprotrusion is damaged, the area of the damaged portion can be reduced. Furthermore, many of the multimodal microprojections, highest peak height (foot height of the highest peaks belonging to the same microprojections) is to produce the average value H _AVG or more microprojections of the projection height, the external force First, each peak portion is received and sacrificially damaged, thereby preventing wear of the main body portion lower than the peak of the microprojection and the microprojection having a height lower than that of the multimodal microprojection. This can also reduce local deterioration of the antireflection function and further reduce the occurrence of poor appearance.

  2 to 6 described above are measurement results of the antireflection article according to the embodiment of the present invention. In the frequency distribution shown in FIG. 5, the distance d between adjacent protrusions (value on the horizontal axis). ), There are two types of maximum values, short-range maximum values of 20 nm and 40 nm and long-range maximum values of 120 nm and 164 nm. Among these maximum values, the maximum value of the long distance corresponds to the arrangement of the microprojection bodies (the part from the middle to the heel below the top part), while the maximum value of the short distance exists in the vicinity of the top part. Corresponds to the apex (peak) of. As a result, the presence of multi-peaked microprotrusions can be seen also from the frequency distribution of the distance between the maximal points.

  In addition, when multi-peaked microprojections coexist in this way, the antireflection performance can be improved as compared with the case of using only single-peaked microprojections. That is, the microprotrusions 51B as shown in FIGS. 10 and 11 and the like are unimodal microprotrusions even when the distance between adjacent protrusions is the same or when the protrusion height is the same. Compared with this, the reflectance of light is further reduced. The reason is that the multimodal microprotrusions 51B have a smaller change rate in the height direction of the effective refractive index in the vicinity of the apex than the monomodal microprotrusions having the same shape below the top (the middle and the heel). Because of that.

That is, in FIG. 10, when the height H is z, a virtual cutting plane Z = perpendicular to the height direction (Z-axis direction) with respect to Z = z (where z = 0 is set to height H = 0). The effective refractive index n _ef obtained as an average value of the refractive index of the microprotrusions and the surrounding medium (usually air) on the surface Z = z when it is assumed that the microprotrusions 51 and 52 are cut by z is: The refractive index of the surrounding medium (here, air) at the cutting plane Z = z is n _A = 1, the refractive index of the constituent material of the minute protrusions 51, 52,... Is nM> 1, and the surrounding medium ( the sum of the cross-sectional area of the air) _S a (z), when the minute projections 51 and 52, the total value of the cross-sectional area of ... was _S M (z),
n _ef (z) = 1 × S _A (z) / (S _A (z) + S _M (z)) + n _A × S _M (z) / (S _A (z) + S _M (z)) (Formula 1 )
Is represented. This is because the refractive index n _A of the peripheral medium and the refractive index n _M of the constituent material of the microprojections are proportional to the total area S _A (z) of the peripheral medium and the total value S _M (z) of the total cross-sectional area of the microprojections, respectively. The allocated value.

Here, when considering a single-peak microprojection as a reference, the multi-peak microprojection 51B is divided into a plurality of peaks near the top. Therefore, in the virtual cutting plane Z = z that cuts the vicinity of the top, the multi-peak microprojection 51B has a total cross-sectional area S _A of the peripheral medium that has a relatively low refractive index compared to the single-peak microprojection. The ratio of (z) is further increased as compared with the ratio of the total cross-sectional area S _M (z) of the microprojections having a relatively high refractive index.

As a result, the effective refractive index n _ef (z) at the virtual cut surface Z = z is higher in the refractive index n of the peripheral medium in the multimodal microprojections 52A than in the monomodal microprojections. Close to _A. Plane Z = z to in multimodal of the difference between the refractive index of the organic效屈folding rate and surrounding medium microprojection _{| n ef (z) -n A} (z) | multi, organic unimodal microprotrusion效When _{mono, |} a difference in refractive index between the peripheral medium _{| n ef (z) -n a} (z)
| N _ef (z) −n _A (z) | _multi <| n _ef (z) −n _A (z) | _mono (Expression 2)
And become. Here, when n _A (z) = 1,
| N _ef (z) -1 | _multi <| n _ef (z) -1 | _mono (Formula 2A)
It becomes.

  Thereby, when the microprotrusions on the surface of the antireflection article 1 include multimodal microprotrusions (including a peripheral medium between the microprotrusions), compared to the case where only the single-peak microprotrusions are included, More specifically, the difference between the effective refractive index and the refractive index of the surrounding medium (air) is to reduce the rate of change of the refractive index per unit distance in the height direction of the microprojections, in other words, to increase the refractive index. It can be seen that it is possible to further increase the continuity of the direction change.

In general, when light is incident on an interface between an adjacent medium having a refractive index n0 and a medium having a refractive index n1, the reflectance R of the light at the interface is set as an incident angle = 0.
R = (n1-n0) ² / (n ₁ + n ₀ ) 2 (Formula 3)
And become. From this equation, the smaller the refractive index difference n ₁ -n ₀ between the media on both sides of the interface, the lower the light reflectivity R at the interface, and as (n ₁ -n ₀ ) approaches 0, R also approaches 0. It will be.

  From (Equation 2), (Equation 2A), and (Equation 3), only the single-peaked microprotrusions exist because the multi-protrusion microprojections 51B are mixed in the microprotrusions on the surface of the antireflection article 1. The reflectance of light is reduced compared with the case of doing so.

  Even in the case of only a single-peaked microprojection, by setting the maximum value dmax of the distance between adjacent projections to a sufficiently small value equal to or less than the shortest wavelength Λmin of the wavelength band of the electromagnetic wave for preventing reflection, sufficient It is possible to exhibit an antireflection effect. However, in this case, since the distance between adjacent peaks and the distance between adjacent minute protrusions are the same, a phenomenon (so-called sticking) in which adjacent minute protrusions are brought into contact with each other and integrated together is likely to occur. When sticking occurs, the substantial distance d between adjacent protrusions increases by the number of minute protrusions integrated together.

  For example, when four microprojections with d = 200 nm are stuck, the size of the stuck and integrated projection is substantially d = 4 × 200 nm = 800 nm> the longest wavelength in the visible light band (780 nm). The antireflection effect is locally impaired.

On the other hand, in the case of the microprojection group including the multimodal microprotrusions 51B, the distance between adjacent protuberances d ^PEAK between the peaks in the vicinity of the apex is larger than the distance between adjacent protuberances d _BASE of the microprotrusion main body from the heel to the middle. It becomes smaller (d ^PEAK <d _BASE ) and is usually about d ^PEAK = d _BASE / 4 to d _BASE / 2. Therefore, sufficient antireflection performance can be obtained by setting the distance d ^PEAK << λmin between adjacent protrusions between the peaks. However, each peak of the multi-peak microprojection has a small ratio of the height of the peak to the width of the ridge, and 1 / of the ratio of the height of the apex to the width of the ridge of the single-peak microprojection. It is about 2 to 1/10. Therefore, for the same external force, the peak of the multimodal microprotrusions is less likely to deform than the single-peak microprotrusions. Moreover, the main body itself of the multimodal microprotrusions has a larger distance between adjacent protrusions and a higher strength than the ridges. Therefore, after all, the microprojection group composed of multimodal microprotrusions can easily achieve both stickiness and low reflectivity compared to the projection group composed of monomodal microprotrusions.

  In addition, even if it is other uses for antireflection of visible light, or in a visible light environment, it depends on the assumed antireflection wavelength depending on the environmental conditions in which the antireflection material is installed and used. By forming a moth eye and providing a height distribution, as mentioned above, even when using materials with lower hardness due to process requirements, etc., they prevent sticking to each other In addition, it is possible to produce an antireflection material having both optically required performance. For example, when it is desired to obtain antireflection performance in the ultraviolet region around 380 nm, the height of the moth eye can be about 50 nm. Similarly, in the infrared region around 700 nm, about 150 nm to 400 nm in consideration of practical use. Is possible. As described above, it is possible to find the manufacturing conditions that saturate the height of the arrangement pitch of the moth-eye, and to effectively control the reflectance of the moth-eye. Furthermore, with regard to the top structure of the moth eye, by adding improvements from the conventional single peak, it is possible to achieve both height and reflectivity, and it is difficult to cause physical sticking and can effectively reduce reflectivity. ing.

  By the way, in order to form the convex projection group 5 in the antireflection article 1, it is essential that the height of each minute projection has a predetermined range.

  In roll plates used for the production of microprojections, by repeating alternating anodizing treatment and etching treatment, the microholes are dug while expanding the hole diameter, thereby producing microholes for the molding of individual microprojections. Is done. This variation in the height of the minute holes is due to variation in the depth of the minute holes produced in the roll plate, and such variation in the depth of the minute holes is caused by variation in the anodizing process. It can be said. Accordingly, the top microprojections 51 having a relatively high height and the plurality of peripheral microprojections 52 having a relatively low height can be mixed by increasing the variation in anodizing treatment. .

  As a specific example, as will be described later, when the conditions in the anodizing treatment are limited to a predetermined range, the variation of the microholes varies based on a certain regularity, and the antireflection article 1 protrudes at a certain rate. It is known that the group of protrusions 5 is formed.

  A multi-peak microprotrusion is created by a microhole having a concave portion corresponding to the top of the microprotrusion, and such a microhole is etched very closely. It is thought that it is produced integrally by processing. As a result, the multi-peak microprojections and the single-peak microprotrusions can be mixed by increasing the variation in the anodizing process.

  Accordingly, in this embodiment, conditions in the anodizing process are set so as to increase the variation, and the top microprojections 51 having a relatively high height and the plurality of peripheral microprojections 52 having a relatively low height are arranged. Are produced, and an anti-reflective article in which convex protrusion groups are formed at a certain ratio is produced.

  Here, the applied voltage (formation voltage) in the anodic oxidation treatment and the interval between the minute holes are in a proportional relationship, and the variation increases when the applied voltage deviates from a certain range. As a result, using an aqueous solution of sulfuric acid, oxalic acid, and phosphoric acid having a concentration of 0.01M to 0.03M, a voltage of 15V (first step) to 35V (second step: about 2.3 times that of the first step) ), A roll plate for producing an antireflective article in which the heights of the minute protrusions vary can be produced. When the applied voltage fluctuates, the variation in the gap between the micro holes increases, so that the applied voltage is intentionally varied, for example, when the applied voltage is generated using an alternating current power source biased by a direct current power source. Also good. Further, the anodizing treatment may be performed using a power source having a large voltage fluctuation rate.

  FIG. 12 is a diagram showing a cross-sectional profile of the convex projection group 5 measured and analyzed by AFM. In FIG. 12, the convex protrusion group 5 in which three peripheral minute protrusions 52 (P2) are formed around one top minute protrusion 51 (P1) can be seen. FIG. 12 is a cross-sectional profile of a case where an oxalic acid aqueous solution having a water temperature of 20 ° C. and a concentration of 0.02 M is applied, and an anodizing process is performed for 120 seconds with an applied voltage of 40V. In the etching process, an anodic oxidation solution was applied to the first step, and a phosphoric acid aqueous solution having a water temperature of 20 ° C. and a concentration of 1.0 M was applied to the second step. The number of times of anodizing treatment and etching treatment is 3 (~ 5) times.

  Further, when the formation surface of the microprojection group was observed from above when the anodic oxidation treatment was performed under the same conditions as described above, about 10% of the microprojections out of 219 microprojections whose existence was confirmed by image analysis. However, it was confirmed that the convex protrusion group 5 was comprised.

  According to the above configuration, by providing a distribution in the height of the microprojections, a convex projection group in which a plurality of peripheral microprojections surround one top microprojection is formed, compared to the conventional case. Thus, the scratch resistance and slipperiness of the antireflection article can be improved.

[Other Embodiments]
The specific configuration suitable for the implementation of the present invention has been described in detail above. However, the present invention is not limited to the configuration of the above-described embodiment, and further the conventional configuration without departing from the spirit of the present invention. Can be combined.

  That is, in the above-described embodiment, the case where the number of repetitions of the anodizing process and the etching process is set to 3 (~ 5) has been described, but the present invention is not limited to this, and the number of repetitions is set to other numbers. In addition, the present invention can be widely applied to the case where the process is repeated a plurality of times and the final process is anodized.

  In the above-described embodiment, the case where the antireflection article is arranged on the front side surface of various image display panels such as a liquid crystal display panel, an electroluminescent display panel, a plasma display panel, etc. has been described. However, the present invention is not limited to this. For example, it can be widely applied to the case where it is disposed on the back side of a liquid crystal display panel to reduce the reflection loss of incident light from the backlight to the liquid crystal display panel (increase the incident light utilization efficiency). Can do. Here, the surface side of the image display panel is a light output surface of the image display panel and also a surface on the image observer side. The back side of the image display panel is the opposite side of the surface of the image display panel. In the case of a transmissive image display apparatus using a backlight (back light source), the incident light from the backlight is incident. It is also a surface.

  In the above-described embodiment, the case where an acrylate-based ultraviolet curable resin is applied to the shaping resin has been described. However, the present invention is not limited to this, and various ultraviolet curable resins such as epoxy-based and polyester-based resins, Alternatively, when using various materials such as acrylate-based, epoxy-based, polyester-based and other electron beam-curable resins, urethane-based, epoxy-based, and polysiloxane-based thermosetting resins, and various curing forms of molding resins Furthermore, the present invention can be widely applied to, for example, when a heated thermoplastic resin is pressed and shaped.

  In the above-described embodiment, as shown in FIG. 1, the microprojection group is formed on the receiving layer 4 of the laminate formed by laminating the receiving layer (ultraviolet curable resin layer) 4 on one surface of the substrate 2. And the receiving layer 4 is cured to form the antireflection article 1. The layer structure is a two-layer laminate. However, the present invention is not limited to such a form. Although the illustration is omitted, the antireflection article 1 of the present invention may have a single-layer configuration in which microprojections are formed directly on one surface of the substrate 2 without interposing another layer. Alternatively, one or more intermediate layers on one surface of the substrate 2 (layers that improve substrate surface performance such as interlayer adhesion, coating suitability, surface smoothness, etc. Also referred to as primer layer, anchor layer, etc. 3), the receiving layer 4 may be formed, and a micro-projection group may be formed on the surface of the receiving layer.

  Furthermore, in the above-described embodiment, as shown in FIG. 1, the microprojection group is formed only on one surface of the base material 2 (directly or via another layer). It is not limited to. The structure which formed the microprotrusion group each on both surfaces of the base material 2 (directly or through another layer) may be sufficient. Although not shown in the drawings, as shown in FIG. 1 and the like, in the antireflection article 1 of the present invention, the surface opposite to the surface on which the microprojections are formed of the substrate 2 (the lower surface of the substrate 2 in FIG. 1). Various adhesive layers are formed on the adhesive layer, and a release film (release paper) is laminated on the surface of the adhesive layer so as to be peelable. In such a form, the release film is peeled and removed to expose the adhesive layer, and the antireflection article 1 of the present invention can be laminated and laminated on the desired surface of the desired article by the adhesive layer. The antireflection performance can be easily imparted to a desired article. As the adhesive, various types of known adhesive forms such as pressure-sensitive adhesive (pressure-sensitive adhesive), two-component curable adhesive, ultraviolet curable adhesive, thermosetting adhesive, and hot melt adhesive can be used. .

  Although not shown, in the antireflection article 1 of the present invention as shown in FIG. 1 and the like, storage, transportation, sale, and post-processing are performed with a protective film that can be peeled off temporarily formed on the surface where the microprojections are formed. Or it can also be set as the form which peels and removes this protective film at an appropriate time after performing construction. In such a configuration, it is possible to prevent the antireflection performance from being deteriorated due to damage or contamination of the microprojection group during storage, transportation, or the like.

  In the above-described embodiment, as shown in FIGS. 1 and 10A, the surface connecting the valley bottoms (minimum heights) between adjacent minute protrusions is a flat surface having a constant height. The present invention is not limited to this, and as shown in FIG. 12, the envelope surface connecting the valley bottoms between the microprotrusions has a period D (that is, D> λmax) equal to or longer than the longest wavelength λmax of the visible light band. A wavy configuration may be used. In addition, the periodic undulation is constant in only one direction (for example, the X direction) on the XY plane (see FIGS. 10 and 12) parallel to the front and back surfaces of the substrate 2 and in a direction orthogonal to the direction (for example, the Y direction). The height may be sufficient, or the two directions (X direction and Y direction) in the XY plane may have undulations. The uneven surface 6 that undulates with a period D satisfying D> λmax is superimposed on a microprojection group composed of a large number of microprojections, so that the reflected light remaining without being completely prevented from being reflected by the microprojection group is scattered, so that Reflected light, particularly specularly reflected light, can be made more difficult to visually recognize, and the antireflection effect can be further improved.

In addition, when the period D of the uneven surface 6 has a distribution that is not constant over the front surface, the frequency distribution of the distance between the protrusions is obtained for the uneven surface, and the average value is D _AVG and the standard deviation is Σ. When
D _MIN = D _AVG -2Σ
Designed as an alternative to period D with a minimum inter-protrusion distance defined as That is, conditions that can sufficiently exhibit the scattering effect of the reflected light of the microprojections are as follows:
D _MIN > λmax
It is. Usually, D or D _MIN is 1 to 200 μm, preferably 10 to 100 μm.
An example of a specific manufacturing method for forming a concavo-convex microprotrusion group having an uneven surface 6 in which the envelope shape connecting the valley bottoms of each microprotrusion is D (or D _MIN )> λmax is as follows. is there. That is, in the manufacturing process of the roll plate 13, a concavo-convex shape corresponding to the concavo-convex shape of the concavo-convex surface 6 is formed on the surface of a cylindrical (or columnar) base material by sandblasting or mat (matte) plating. Next, an appropriate intermediate layer is formed on the uneven surface directly or as necessary, and then an aluminum layer is laminated. Thereafter, an anodizing process and an etching process are performed on the aluminum layer shaped to have a surface shape corresponding to the uneven surface to form a microprojection group including the convex projection group 5 in the same manner as in the above embodiment.

  In the above-described embodiment, the case where an antireflection article having a film shape is produced by a forming process using a roll plate is described. However, the present invention is not limited to this, and the transparent substrate according to the shape of the antireflection article is used. Depending on the shape of the mold, for example, when creating an antireflection article by processing a flat plate or a single wafer using a mold for molding with a specific curved surface shape, the process related to the molding process, the mold is an antireflection article It can change suitably according to the shape of the transparent base material which concerns on the shape of this.

  In the above-described embodiment, the case where the antireflection article having the film shape is arranged on the front side surface of the image display panel or the incident surface of the illumination light has been described. However, the present invention is not limited to this and is used for various applications. Can be applied. Specifically, it should be applied to applications that are placed on the back surface (image display panel side) of the surface side member such as a touch panel, various window materials, various optical filters, etc. installed on the screen of the image display panel through a gap. Can do. In this case, the occurrence of interference fringes such as Newton rings due to light interference between the image display panel and the surface side member is prevented, and the light emission surface of the image display panel and the light incident surface side of the surface side member are It is possible to prevent ghost images due to multiple reflections between them, and to achieve effects such as reduction of reflection loss with respect to image light emitted from the screen and entering these surface side members.

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

  Further, the present invention can be widely applied to the case where the lens or prism is used on various optical devices such as glasses, a telescope, a camera, a video camera, a gun sighting mirror (sniper scope), binoculars, and a periscope. In this case, the visibility by preventing light reflection on the lens or prism surface can be improved. Further, it can also be applied to the case where the book is placed on the surface of a printed part (characters, photos, drawings, etc.), thereby preventing light reflection on the surface of characters and the like and improving the visibility of characters and the like. In addition, it is placed on the surface of signs (posters, posters, other stores, streets, exterior walls, etc.) (road guidance, maps, smoking cessation, entrances, emergency exits, no entry, etc.) to improve visibility. be able to. In addition, light incident on window materials for lighting fixtures using incandescent bulbs, light-emitting diodes, fluorescent lamps, mercury lamps, EL (electroluminescence), etc. (sometimes also serving as diffusers, condensing lenses, optical filters, etc.) By arranging it on the surface side, it is possible to prevent light reflection on the light incident 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 devices to prevent light reflection on the display window surface and improve visibility.

  In addition, it is arranged on the inside, outside, or both sides of the windows of the cockpit (driver's cab, wheelhouse) of vehicles such as automobiles, railway vehicles, ships, and aircraft to reflect indoor and outdoor light. Therefore, it is possible to improve the visibility of the outside world of the driver (driver, driver). Furthermore, it can be arranged on the lens or window material surface of a night vision device used for surveillance of crime prevention, gun sighting, astronomical observation, etc., thereby improving visibility at night and in the dark.

  In addition, the surface (indoor side, outdoor side, or both sides) of transparent substrates (window glass, etc.) constituting windows, doors, partitions, wall surfaces, etc. of buildings such as houses, stores, offices, schools, hospitals, etc. ), The visibility of the outside world, or the lighting efficiency can be improved.

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

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

DESCRIPTION OF SYMBOLS 1 Antireflection article 2 Base material 4 Ultraviolet curable resin layer, receiving layer 5 Convex protrusion group 51 Top microprotrusion 52 Peripheral microprotrusion 6 Concavity and convexity 10 Manufacturing process 12 Die 13 Roll plate 14, 15 Roller g Groove

Claims (5)

A mold for manufacturing an antireflective article for use in manufacturing an antireflective article,
The antireflective article is
The microprotrusions are placed in close proximity,
The interval between the adjacent minute protrusions is equal to or less than the shortest wavelength of the wavelength band of the electromagnetic wave for preventing reflection,
A convex shape comprising a part of the microprotrusions and a plurality of peripheral microprotrusions formed adjacent to the periphery of the top microprotrusions and having a height lower than that of the top microprotrusions. A group of protrusions,
Of the microprojections, the ratio of microprojections constituting the convex projection group is 10% or more,
The fine protrusions constituting one convex protrusion group are:
The standard deviation varies from 30 nm to 50 nm, and the height varies.
At least a part of the microprojections is
It is a multimodal microprotrusion with multiple vertices,
The multimodal microprotrusions are
With the radial grooves formed at the top, the top is a shape divided into peaks relating to each vertex,
The mold for manufacturing the antireflection article is:
A mold for manufacturing an antireflective article, in which fine holes corresponding to the fine protrusions are in close contact with each other. The mold for manufacturing an antireflective article according to claim 1 , wherein the plurality of peripheral microprojections have a height that decreases with distance from the top microprojections. A part of a curved surface including each vertex of the microprotrusions,
In the envelope surface of the convex projection group, which is a bell-shaped curved surface that widens from the apex of the top microprojection to the lower end,
The mold for manufacturing an antireflection article according to claim 1 or 2 , wherein a maximum distance between the lower end portions of the envelope surface is 780 nm or less. The mold for manufacturing an antireflective article according to claim 3 , wherein the maximum distance between the lower end portions is 380 nm or less.   The antireflection article is produced by a molding process using the mold for manufacturing an antireflection article according to claim 1, claim 2, claim 3, or claim 4.
  A method for manufacturing an antireflection article.