JP2010253819A - Aluminum base material for producing stamper and method for producing stamper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum base material with which a stamper can be obtained which makes macro-unevenness and irregular color generated on a transfer surface difficult to be visually recognized. <P>SOLUTION: The aluminum base material 10, having a processed surface on which a fine irregular structure is to be formed, is used for production of the stamper 20 having the fine irregular structure on the surface. In the aluminum base material 10, a plurality of intermetallic compounds exposed to the processed surface exist on the processed surface, the total area of the intermetallic compounds exposed to the processed surface is >0.14% and ≤0.7% based on the area (100%) of the processed surface, and the arithmetic average roughness Ra of the processed surface is 0.05 μm or below. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a stamper having a fine concavo-convex structure on the surface, which is used for producing antireflection articles and the like, and an aluminum substrate used for producing the stamper.

  In recent years, articles having a fine concavo-convex structure with a period of less than or equal to the wavelength of visible light on the surface exhibit an antireflection function, a Lotus effect, and the like, and thus have been attracting attention for their usefulness. In particular, it is known that a fine concavo-convex structure called a moth-eye structure exhibits an effective antireflection function by continuously increasing from a refractive index of air to a refractive index of a material.

As a method for producing an article having a fine concavo-convex structure on the surface, the following method is known, and the method (ii) is excellent from the viewpoint of productivity and economy.
(I) A method for producing an article having a fine concavo-convex structure on its surface by directly processing the surface of a transparent substrate or the like.
(Ii) A method of transferring the inverted structure onto the surface of a transparent substrate or the like using a stamper having an inverted structure corresponding to the fine concavo-convex structure.

As a method for forming an inversion structure in a stamper, an electron beam drawing method, a laser beam interference method, and the like are known. In recent years, a method of anodizing the surface of an aluminum substrate has attracted attention as a method for forming an inverted structure more easily (see, for example, Patent Document 1).
Anodized alumina formed by anodizing the surface of an aluminum substrate is an aluminum oxide film (alumite) and has a fine concavo-convex structure consisting of a plurality of pores whose period is equal to or less than the wavelength of visible light.

However, by using a stamper having anodized alumina formed on the surface, optical articles such as antireflection articles such as antireflection films (including antireflection films and antireflection sheets) can be used as described in (ii). When manufactured by the method, the following problems occur, and a product suitable for optical use may not be obtained.
(1) When the aluminum substrate is a rolled product, the rolling trace is transferred to the article.
(2) The step of increasing the arrangement regularity of the pores increases the step of the crystal grain boundary, and the step is transferred to the article to form macro unevenness that can be visually recognized.
(3) Even if the level difference of the crystal grain boundary is small and macro unevenness is not visible, color unevenness occurs in the articles because the easiness of anodization differs for each crystal plane.

JP 2005-156695 A

  INDUSTRIAL APPLICABILITY The present invention can make it difficult to visually recognize macro unevenness and color unevenness generated on a transfer surface, an aluminum base material that can obtain a stamper that can make macro unevenness and color unevenness generated on the transfer surface difficult to visually recognize. A method for manufacturing a stamper is provided.

  As a result of intensive studies, the present inventors have found that macro unevenness and color unevenness on the transfer surface become inconspicuous by imparting appropriate haze to the transfer surface.

  Accordingly, the present inventors have found that the total area of the intermetallic compounds exposed on the work surface is more than 0.14% and 0.7% or less with respect to the work surface area (100%). The anodized surface of the aluminum substrate having an arithmetic average roughness Ra of 0.05 μm or less results in a fine uneven structure consisting of a plurality of pores having a period equal to or less than the wavelength of visible light. At the same time, a rough concavo-convex structure capable of giving an appropriate haze to the transfer surface is formed on the transfer surface by removing the intermetallic compound, and by using such a stamper, The present inventors have found that it is possible to provide haze at a level that causes no problem in practical use, and that it is possible to provide an article in which macro unevenness and color unevenness on the transfer surface are difficult to visually recognize, thereby completing the present invention.

  That is, the aluminum substrate for manufacturing a stamper according to the present invention is an aluminum substrate having a processed surface on which the fine concavo-convex structure is formed, which is used for manufacturing a stamper having a fine concavo-convex structure on the surface. The surface has a plurality of intermetallic compounds exposed on the processing surface, and the total area of the intermetallic compounds exposed on the processing surface is the area of the processing surface (100%), It is more than 0.14% and 0.7% or less, and the arithmetic average roughness Ra of the work surface is 0.05 μm or less.

The average diameter of the intermetallic compound exposed on the work surface is preferably 0.5 to 3.0 μm.
In the aluminum substrate (100% by mass), the silicon content is 0.1% by mass or less, the iron content is 0.4% by mass or less, and the copper content is 0.3% by mass or less. Preferably there is.
It is preferable that the aluminum base material for stamper production of the present invention is forged.
The average crystal grain size of the aluminum substrate for producing a stamper according to the present invention is preferably 1 mm or less.

In the stamper manufacturing method of the present invention, the processed surface of the aluminum substrate for manufacturing a stamper of the present invention is anodized so that a fine concavo-convex structure having a plurality of pores having a period of 400 nm or less is formed on the processed surface. And forming a rough concavo-convex structure on the work surface by dropping the intermetallic compound.
The aspect ratio (depth / cycle) of the pores is preferably 1.0 or more.

  The stamper manufacturing method of the present invention includes a first oxide film forming step (a) in which an object surface to be processed of the aluminum base is anodized in an electrolytic solution under a constant voltage to form an oxide film on the surface to be processed (a ), An oxide film removing step (b) in which the oxide film is removed and pore generation points for anodic oxidation are formed on the processed surface, and a processed surface of the aluminum substrate on which the pore generation points are formed A second oxide film forming step (c) in which an oxide film having a pore corresponding to the pore generation point is formed on the surface to be processed by anodizing again in an electrolytic solution under a constant voltage; It is preferable to have a pore diameter expansion treatment step (d) for expanding the diameter of the pores.

According to the aluminum substrate of the present invention, it is possible to obtain a stamper that can make it difficult to visually recognize macro unevenness and color unevenness generated on the transfer surface.
According to the stamper manufacturing method of the present invention, it is possible to manufacture a stamper capable of making it difficult to visually recognize macro unevenness and color unevenness generated on the transfer surface.

It is explanatory drawing explaining an example of the manufacturing method of the stamper of this invention. It is sectional drawing which shows an example of the shape of the pore formed in the surface of a stamper. It is sectional drawing which shows the other example of the shape of the pore formed in the surface of a stamper. It is sectional drawing which shows the other example of the shape of the pore formed in the surface of a stamper. It is a block diagram which shows an example of the manufacturing apparatus of the articles | goods which have a fine concavo-convex structure on the surface.

<Aluminum substrate>
The aluminum substrate for manufacturing a stamper of the present invention (hereinafter simply referred to as “aluminum substrate”) has a work surface on which a fine concavo-convex structure is formed, which is used for manufacturing a stamper having a fine concavo-convex structure on the surface. It is an aluminum substrate.
The surface to be processed is a surface that comes into contact with the material when the surface of the stamper is transferred to the material, and is a surface on which a fine concavo-convex structure is formed partially or entirely.
The concavo-convex structure is a structure composed of a plurality of concave portions and / or convex portions.
The period is a distance from the center of the concave portion (or convex portion) of the concavo-convex structure to the center of the concave portion (or convex portion) adjacent thereto.

  A plurality of intermetallic compounds exposed on the processing surface exist on the processing surface. The intermetallic compound is mainly an iron-based compound such as an Fe—Al-based compound.

The total area of the intermetallic compounds exposed on the work surface is more than 0.14% and 0.7% or less with respect to the work surface area (100%).
If the area of the intermetallic compound exceeds 0.14%, the intermetallic compound will be present appropriately, a rough uneven structure can be formed properly, and an appropriate haze is imparted to the article having the stamper surface transferred thereto. Can be granted. In addition, by reducing the crystal grain size of the aluminum substrate and increasing the aspect ratio of the pores, color unevenness on the transfer surface can be reduced, but the aspect ratio of the protrusions on the transfer surface increases, so the transfer surface There is a tendency that the scratch resistance of the is reduced.
If the area of the intermetallic compound is 0.7% or less, the rough uneven structure that scatters visible light does not increase too much, and the decrease in transparency of the article can be suppressed. When pasted as a prevention film, the sharpness of the image does not deteriorate, and an article suitable for optical use can be obtained.
The area of the intermetallic compound can be determined by image analysis from the reflected electron image of the scanning electron microscope. Specifically, the area of the intermetallic compound in the visual field is obtained by image analysis by an automatic image processing analysis system (manufactured by Nireco Corporation, LUZEX-AP), and this is divided by the area of the visual field to obtain the area of the work surface ( 100%) is calculated as a ratio of the total area of the intermetallic compound.

The average diameter of the intermetallic compound exposed on the work surface is preferably 0.5 to 3.0 μm. If the average diameter is 0.5 μm or more, the rough concavo-convex structure to be formed becomes larger than the wavelength of visible light, and an appropriate haze can be imparted to the article on which the surface of the stamper is transferred. When the average diameter is 3.0 μm or less, a decrease in peelability when the stamper surface is transferred to a transparent substrate or the like can be suppressed.
The average diameter of the intermetallic compound is an average value of equivalent circle diameters calculated for 100 or more arbitrarily selected intermetallic compounds on the processed surface of the aluminum substrate. Observation of the intermetallic compound on the work surface can be performed with a scanning electron microscope or the like. The average value of the equivalent circle diameter can be obtained by using image analysis software such as LUZEX-AP manufactured by Nireco Corporation. In addition, before observing the processed surface of an aluminum base material with a scanning electron microscope etc., it is preferable to mirror-polish the processed surface of an aluminum base material.

The arithmetic average roughness Ra of the work surface is 0.05 μm or less. When the arithmetic average roughness Ra is 0.05 μm or less, the haze of the article to which the surface of the stamper is transferred does not become too high.
The arithmetic average roughness Ra is defined in JIS B0601-2001.

The average crystal grain size of the aluminum substrate is preferably 1 mm or less, more preferably 300 μm or less, further preferably 0.05 to 200 μm, and particularly preferably 1 to 150 μm. When the average crystal grain size is 1 mm or less, the crystal grain boundary in the stamper is unlikely to appear as macro irregularities that are visible, and as a result, macro irregularities and color unevenness are unlikely to occur on the transfer surface. Such a stamper is suitable for manufacturing an article for optical use such as an antireflection article. If the average crystal grain size is 0.05 μm or more, it is easy to produce an aluminum base material, and it is difficult to form pores across the crystal grain boundary, so that the disturbance of the fine uneven structure can be suppressed.
The average crystal grain size is an average value of equivalent circle diameters calculated for 100 or more arbitrarily selected crystal grains on the processed surface of the aluminum base. Observation of crystal grains on the surface to be processed can be performed with an optical microscope or the like, and the average value of equivalent circle diameters can be obtained by using image analysis software such as Image-Pro PLUS manufactured by Nippon Roper. In addition, before observing the processed surface of an aluminum base material with an optical microscope etc., it is preferable to grind the processed surface of an aluminum base material and to carry out an etching process.

  The aluminum purity of the aluminum base is preferably more than 99.5% by mass and less than 99.92% by mass, more preferably 99.7% by mass to 99.92% by mass, and more preferably 99.8% by mass to 99.92% by mass. The following is more preferable. If the aluminum purity is more than 99.5% by mass, the number of rough uneven structures that scatter visible light does not increase too much, and the decrease in transparency of the article can be suppressed. For example, an antireflection film is formed on the outermost surface of the display. As a result, the sharpness of the image does not deteriorate and an article suitable for optical use can be obtained. If the aluminum purity is 99.92% by mass or less, an intermetallic compound will be present appropriately, a rough uneven structure can be formed appropriately, and an appropriate haze can be imparted to an article having the stamper surface transferred thereto. . In addition, by reducing the crystal grain size of the aluminum substrate and increasing the aspect ratio of the pores, color unevenness on the transfer surface can be reduced, but the aspect ratio of the protrusions on the transfer surface increases, so the transfer surface There is a tendency that the scratch resistance of the is reduced.

  The content of trace components inevitable in production contained in the aluminum substrate (100% by mass) is that the silicon content is 0.1% by mass or less and the iron content is 0.4% by mass or less. It is preferable that the copper content is 0.3% by mass or less. If there is too much content of inevitable trace components in production, there will be a part where pores are not formed by anodic oxidation, the reflectivity of the article with the stamper surface transferred will not be sufficiently low, transparency will be reduced, etc. The above problem may occur.

As a method for producing an aluminum substrate, a forging process or the like is performed on an aluminum ingot (ingot) to finely uniform aluminum crystal grains, and then cut into a desired shape such as a plate shape, a columnar shape, a cylindrical shape, or the like. After cutting, there is a method in which the surface is mirrored by polishing or the like.
Examples of the method for mirror-finishing the surface include methods such as mechanical polishing, bedding polishing, chemical polishing, and electrochemical polishing (such as electrolytic polishing).

  In order to set the average crystal grain size of the aluminum base material to 1 mm or less and the arithmetic average roughness Ra of the work surface to 0.05 μm or less, as described later, the aluminum ingot is subjected to a forging process, and the average of the aluminum It is preferable that the arithmetic average roughness Ra of the surface to be processed is 0.05 μm or less by polishing after making the crystal grain size fine and uniform so as to be 1 mm or less and processing into a desired shape.

As a method for fine uniformization, a processing method that gives a greater degree of processing to the material is adopted. As a processing method, a rolling process or a forging process is preferable. However, in the case of a rolling process, since the processing direction is limited to one direction, the degree of processing may be limited depending on the ingot size and the substrate size. Further, since the processing direction is limited to one direction, a non-uniform structure extending in a streak shape in the rolling direction may be formed. When a stamper is manufactured using an aluminum base material having such a non-uniform structure, the non-uniform structure appears as a macro pattern, and the non-uniform macro pattern also appears on the transfer surface formed from such a stamper. It will occur. As a result, further processing is required to remove more uneven tissue.
In the case of the forging process, the processing direction can be freely changed, so that it is possible to give the material a greater degree of processing than the rolling process. Therefore, the forging process is more preferable in that a fine uniform structure can be obtained by a simpler method. In addition, for the same reason as described above, in order to set the arithmetic average roughness Ra of the work surface to 0.05 μm or less, the non-rolled aluminum base material that has not been subjected to the rolling treatment, or after the rolling treatment, It is preferable to use an aluminum substrate from which a non-uniform structure resulting from the treatment has been removed.
Hereinafter, the forging process will be described in detail.

(Forging process)
As the forging process, hot forging is preferable, and a combination of hot forging and cold forging is more preferable. Further, it is preferable to further perform a heat treatment after the forging process.

Hot forging:
High purity aluminum ingots tend to be coarse and non-uniform structures, and hot forging is performed in order to destroy the coarse and non-uniform structures of the ingot and obtain a fine uniform structure by recrystallization. Before being subjected to forging, the cut casting material is charged into a heating furnace and heated to 400 to 500 ° C. before forging. The heating temperature at this time is important for making the structure fine and uniform. Next, a forged product is manufactured by free forging of the material heated to 400 to 500 ° C. If the heating temperature at this time exceeds 500 ° C., the recrystallized grains at the time of hot forging tend to be coarsened. Conversely, at a heating temperature that does not reach 400 ° C., traces of the coarse structure of the ingot tend to remain unevenly. At the same time, deformation resistance during forging increases, and cracks are likely to occur in the forged product or stamper. The heating and holding is performed for about 1 hour in order to make the temperature uniform. When the forging molding ratio is large, the coarse inhomogeneous structure of the ingot is less likely to remain. When (1 / 2U-2S) or (2S-1 / 2U) is 1 cycle, 2 cycles or more are preferable, and 3 cycles or more. Is more preferable, and 4 cycles or more are more preferable. However, when the number of forging cycles is large, the temperature drop of the forged product becomes large, so that it easily falls below the recrystallization temperature. When it falls below 350 ° C. during hot forging, it is necessary to reheat to 400 ° C. or higher.

Cold forging:
Cold forging is performed to further refine the fine uniform structure obtained by hot forging. Allow the material to cool to room temperature or below. The material is crushed in the vertical direction by die forging to produce a forged product. Alternatively, a forged product can be manufactured by free forging. Accumulation of strain by cold forging is aimed at obtaining a fine structure after the subsequent heat treatment, and it is easier to obtain a fine structure if the forging ratio is increased within a range in which defects such as cracks do not occur. When (1 / 2U-2S) or (2S-1 / 2U) is 1 cycle, it is preferably 1 cycle or more and 3 cycles or less, and more preferably 2 cycles or more and 3 cycles or less. Forging ratios exceeding 3 cycles are prone to cracking. Even in the case of a wrought molding ratio of 3 cycles or less, if the material heats up due to forging and the temperature exceeds 200 ° C., the strain is gradually released at that time, making it difficult to obtain a microstructure after heat treatment. For this reason, when it is likely to exceed 200 ° C., it is necessary to interrupt the temporary forging, perform air cooling or water cooling, and limit the release of strain.

Heat treatment:
The heat treatment is performed in order to cause recrystallization due to the strain accumulated in the forged product and obtain uniform fine crystal grains. Forged products have accumulated strain introduced during processing. Using this strain as a driving force, a large number of fine recrystallized grains can be generated all at once, and uniform and fine crystal grains can be obtained. As heat processing temperature, 300-500 degreeC is preferable and 300-400 degreeC is more preferable. When the temperature is lower than 300 ° C., a part of the forged structure may remain. On the other hand, when the temperature is higher than 500 ° C., the growth of recrystallized grains becomes remarkable and the crystal grains become large. The heat treatment time is preferably 30 minutes or longer, and more preferably 1 hour or longer. If the treatment time is less than 30 minutes, there is a problem that recrystallization is not completed and a forged structure remains.

  In the aluminum substrate of the present invention described above, there are a plurality of intermetallic compounds exposed on the work surface, and the total area of the intermetallic compounds is more than 0.14% and 0.7% or less. Since the arithmetic average roughness Ra of the surface to be processed is 0.05 μm or less, the intermetallic compound drops off during the pretreatment or anodization of the aluminum base material and scatters a plurality of relatively large holes, that is, light. A rough concavo-convex structure is appropriately formed. In addition, a plurality of pores (fine concavo-convex structure) whose period is equal to or less than the wavelength of visible light are formed on the surface to be processed by anodic oxidation. By using such a stamper, it is possible to impart a level of haze that causes no practical problem to the transfer surface, and it is possible to obtain an article in which macro unevenness and color unevenness on the transfer surface are difficult to visually recognize.

<Stamper manufacturing method>
The stamper manufacturing method of the present invention is a method in which an intermetallic compound is removed by pretreating or anodizing the processed surface of the aluminum base material of the present invention to form a rough uneven structure on the processed surface, and the processed surface This is a method for forming a fine concavo-convex structure consisting of a plurality of pores having a period equal to or less than the wavelength of visible light on the surface to be processed.

As a stamper manufacturing method, a method of sequentially performing the following steps is preferable.
First oxide film forming step (a);
The processed surface of the mirror-finished aluminum base material is anodized in an electrolytic solution under a constant voltage to form an oxide film on the processed surface (hereinafter also referred to as step (a)).
Oxide film removal step (b);
The oxide film is removed, and pore generation points for anodic oxidation are formed on the surface to be processed (hereinafter also referred to as step (b)).
Second oxide film forming step (c);
The processed surface of the aluminum base material on which the pore generation point is formed is anodized again under a constant voltage in the electrolytic solution, and an oxide film having pores corresponding to the pore generation point is formed on the processed surface. (Hereinafter also referred to as step (c)).
Pore diameter expansion treatment step (d);
The diameter of the pores is enlarged (hereinafter also referred to as step (d)).
Repeating step (e);
If necessary, the second oxide film forming step (c) and the hole diameter expanding treatment step (d) are repeated (hereinafter also referred to as step (e)).

  According to the method including the steps (a) to (e), tapered pores whose diameter gradually decreases in the depth direction from the opening are periodically formed on the processed surface of the mirror-finished aluminum base material. As a result, it is possible to obtain a stamper in which anodized alumina having a fine relief structure is formed on the surface.

Before the step (a), a pretreatment for removing the oxide film on the processed surface of the aluminum base material may be performed. Examples of the method for removing the oxide film include a method of dipping in a chromic acid / phosphoric acid mixed solution.
Further, although the regularity of the arrangement of the pores is slightly lowered, the step (a) may be omitted from the step (c) depending on the use of the material to which the surface of the stamper is transferred.
Hereinafter, each process will be described in detail.

(Process (a))
In the first oxide film forming step (a), the processed surface of the mirror-finished aluminum base material is anodized under a constant voltage in an electrolytic solution, and as shown in FIG. An oxide film 12 having pores 11 is formed on the surface to be processed.
Examples of the electrolytic solution include an acidic electrolytic solution and an alkaline electrolytic solution, and an acidic electrolytic solution is preferable.
Examples of the acidic electrolyte include oxalic acid, sulfuric acid, and a mixture thereof.

When oxalic acid is used as the electrolytic solution, the concentration of oxalic acid is preferably 0.7 M or less. If the concentration of oxalic acid exceeds 0.7M, the current value during anodic oxidation becomes too high, and the surface of the oxide film may become rough.
Further, by setting the voltage during anodic oxidation to 30 to 60 V, it is possible to obtain a stamper having anodic oxidized alumina having highly regular pores with a period of about 100 nm formed on the surface. Regardless of whether the voltage during anodization is higher or lower than this range, the regularity tends to decrease, and the period may be longer than the wavelength of visible light.
The temperature of the electrolytic solution is preferably 60 ° C. or lower, and more preferably 45 ° C. or lower. When the temperature of the electrolytic solution exceeds 60 ° C., a phenomenon called “burning” tends to occur, and the pores may be broken or the surface may melt and the regularity of the pores may be disturbed.

When sulfuric acid is used as the electrolytic solution, the concentration of sulfuric acid is preferably 0.7 M or less. If the concentration of sulfuric acid exceeds 0.7M, the current value at the time of anodization may become too high to maintain a constant voltage.
Further, by setting the voltage during anodization to 25 to 30 V, it is possible to obtain a stamper on which anodized alumina having highly regular pores with a period of about 63 nm is formed on the surface. Regardless of whether the voltage during anodization is higher or lower than this range, the regularity tends to decrease, and the period may be longer than the wavelength of visible light.
The temperature of the electrolytic solution is preferably 30 ° C. or less, and more preferably 20 ° C. or less. When the temperature of the electrolytic solution exceeds 30 ° C., a phenomenon called “burning” tends to occur, and the pores may be broken or the surface may melt and the regularity of the pores may be disturbed.

  In the step (a), the oxide film formed by anodizing for a long time becomes thick and the regularity of the arrangement of the pores can be improved. At this time, the thickness of the oxide film is 2.5 μm. More than 30 μm is suitable. If it is less than 2.5 μm, the intermetallic compound may not be sufficiently removed when anodized without pretreatment, and if it is 30 μm or more, the productivity is lowered.

(Process (b))
After the step (a), the oxide film 12 formed in the step (a) is removed to correspond to the bottom of the removed oxide film 12 (referred to as a barrier layer) as shown in FIG. Periodic depressions, that is, pore generation points 13 are formed (oxide film removal step (b)).
By removing the formed oxide film 12 once and forming pore generation points 13 for anodization, the regularity of the finally formed pores can be improved (for example, Masuda, “Applied Physics”). ", 2000, 69, No. 5, p. 558.).

  Examples of the method for removing the oxide film 12 include a method in which aluminum is not dissolved but is removed with a solution that selectively dissolves alumina. Examples of such a solution include a chromic acid / phosphoric acid mixed solution.

(Process (c))
The aluminum substrate 10 on which the pore generation points 13 are formed is anodized again in the electrolytic solution under a constant voltage to form an oxide film again (second oxide film forming step (c)).
In step (c), anodization may be performed under the same conditions (electrolyte concentration, electrolyte temperature, chemical conversion voltage, etc.) as in step (a).
Thereby, as shown in FIG.1 (c), the oxide film 15 in which the cylindrical pore 14 was formed can be formed. Also in the step (c), the deeper pores can be obtained as the anodic oxidation is performed for a longer time. However, in the case of manufacturing a stamper for manufacturing an optical article such as an antireflection article, here, An oxide film having a thickness of about 0.01 to 0.5 μm may be formed, and it is not necessary to form an oxide film having a thickness enough to be formed in the step (a).

(Process (d))
After the step (c), a pore diameter enlargement process for enlarging the diameter of the pores 14 formed in the step (c) is performed, and as shown in FIG. ) Is larger than in the case of (a hole diameter enlargement process step (d)).
As a specific method of the pore diameter expansion treatment, a method of immersing in a solution dissolving alumina and expanding the diameter of the pores formed in the step (c) by etching can be mentioned. Examples of such a solution include a phosphoric acid aqueous solution of about 5% by mass. The longer the time of step (d), the larger the pore diameter.

(Process (e))
Step (c) is performed again, and as shown in FIG. 1 (e), the shape of the pores 14 is changed to a two-stage cylindrical shape having different diameters, and then step (d) is performed again. By repeating the step (c) and the step (d) as described above, the diameter of the pore 14 is gradually reduced from the opening in the depth direction as shown in FIG. As a result, it is possible to obtain a stamper 20 having an anodized alumina formed with a fine concavo-convex structure formed of a plurality of periodic pores on the surface.

  By appropriately setting the conditions of the step (c) and the step (d), for example, the time for anodization and the time for the pore size expansion treatment, pores having various shapes can be formed. Therefore, these conditions may be set as appropriate according to the use of the article to be manufactured from the stamper. In addition, when this stamper is for manufacturing an antireflection article such as an antireflection film, the period and depth of the pores can be arbitrarily changed by appropriately setting the conditions in this way, so that the optimum It is also possible to design a refractive index change.

  Specifically, if step (c) and step (d) are repeated under the same conditions, a substantially conical pore 14 as shown in FIG. 2 is formed, and the processes of step (c) and step (d) are performed. By appropriately changing the time, it is possible to appropriately form the inverted bell-shaped pores 14 as shown in FIG. 3, the sharp-shaped pores 14 as shown in FIG.

  As the number of repetitions in the step (e), the larger the number, the smoother the tapered pores can be formed, and the total of the step (c) and the step (d) is preferably 3 times or more, more preferably 5 times or more. . If the number of repetitions is 2 times or less, the diameter of the pores tends to decrease discontinuously, and when an antireflection article such as an antireflection film is manufactured from such a stamper, the reflectance reduction effect may be inferior. There is.

The stamper thus manufactured has a fine concavo-convex structure on the surface as a result of the formation of a large number of periodic pores. If the period of the pores in the fine concavo-convex structure is less than or equal to the wavelength of visible light, that is, 400 nm or less, a so-called Moth-Eye structure is obtained, and an effective antireflection function is exhibited.
As shown in FIG. 2, the period is the distance (p in the figure) from the center of the recess (pore) of the fine concavo-convex structure to the center of the recess (pore) adjacent thereto.
When the period is larger than 400 nm, visible light scattering occurs, so that a sufficient antireflection function is not exhibited, and it is not suitable for manufacturing an antireflection article such as an antireflection film.

When the stamper is for producing an antireflection article such as an antireflection film, the period of the pores is preferably not more than the wavelength of visible light, and the depth of the pores is preferably 50 nm or more, and 100 nm. More preferably.
As shown in FIG. 2, the depth is a distance (Dep in the figure) from the opening of the concave portion (pore) of the fine concavo-convex structure to the deepest portion.
If the depth of the pore is 50 nm or more, the reflectance of the surface of the article for optical use formed by the transfer of the stamper surface, that is, the transfer surface is lowered.

  The aspect ratio (depth / cycle) of the pores of the stamper is preferably 1.0 to 4.0, preferably 1.3 to 3.5, more preferably 1.8 to 3.5, 2.0 -3.0 is most preferred. When the aspect ratio is 1.0 or more, a transfer surface with low reflectance can be formed, and the incident angle dependency and wavelength dependency thereof are sufficiently reduced. If the aspect ratio is greater than 4.0, the mechanical strength of the transfer surface tends to decrease.

The shape of the stamper may be a flat plate or a roll.
The surface on which the fine uneven structure of the stamper is formed may be subjected to a release treatment so that the release is easy. Examples of the release treatment method include a method of coating a silicone-based polymer or a fluorine polymer, a method of depositing a fluorine compound, a method of coating a fluorine-based or fluorine-silicone-based silane coupling agent, and the like.

  Moreover, in the above description, a case where pores whose diameter is reduced from the opening in the depth direction is formed by performing the pore diameter enlargement process step (d) after the second oxide film formation step (c). Although illustrated, the step (d) is not necessarily performed after the step (c). In that case, although the formed pores are cylindrical, even in an article for optical applications having a fine concavo-convex structure manufactured by such a stamper, the layer having this structure is used as a low refractive index layer. The effect of acting and reducing reflection can be expected.

  In addition, from the stamper obtained by the production method of the present invention, products such as optical articles can be directly manufactured. First, a replica is prepared using the stamper as a prototype, and an optical article is manufactured from the replica. May be. Alternatively, a replica may be produced again using this replica as a prototype, and an article for optical use may be produced from the replica. As a method for producing a replica, for example, a thin film made of nickel, silver, or the like is formed on a master by electroless plating, sputtering, or the like, and then electroplating (electroforming) is performed using the thin film as an electrode. Examples of the method include a method in which the nickel layer is peeled off from the original mold after being deposited to form a replica.

  In the stamper manufacturing method of the present invention described above, the work surface of the aluminum base material of the present invention is anodized, so that the intermetallic compound on the work surface of the aluminum base material is as described above. A plurality of relatively large holes, that is, a rough concavo-convex structure with a size that scatters light are formed by dropping off during the pretreatment or anodization of the aluminum substrate. In addition, a plurality of pores (fine concavo-convex structure) whose period is equal to or less than the wavelength of visible light are formed on the surface to be processed by anodization. By using such a stamper, it is possible to impart a level of haze that causes no practical problem to the transfer surface, and it is possible to obtain an article in which macro unevenness and color unevenness on the transfer surface are difficult to visually recognize.

<Production method>
By using the stamper obtained by the production method of the present invention, an article having a transfer surface onto which the rough uneven structure and fine uneven structure of the stamper surface are transferred can be manufactured.
Examples of the manufacturing method of the article include the following methods.
(1) An active energy ray curable composition is disposed between a stamper and a transparent substrate, and the active energy ray curable composition is in contact with the active energy ray curable composition in a state where the active energy ray curable composition is in contact with the stamper. After the active energy ray-curable composition is cured by irradiating, the stamper is peeled off, and a rough uneven structure and a fine uneven structure made of a cured product of the active energy ray-curable composition are formed on the surface of the transparent substrate. To obtain a finished article.
(2) An active energy ray-curable composition is disposed between the stamper and the transparent substrate, the rough uneven structure and the fine uneven structure on the surface of the stamper are transferred to the active energy ray-curable composition, and the stamper is peeled off. Thereafter, the active energy ray curable composition is irradiated with active energy rays to cure the active energy ray curable composition, and the surface of the transparent substrate is made of a cured product of the active energy ray curable composition. A method for obtaining an article in which a concavo-convex structure and a fine concavo-convex structure are formed.

Hereinafter, the method (1) will be described in detail.
The stamper and the transparent substrate are opposed to each other, and the active energy ray-curable composition is filled and disposed between them. At this time, the surface on which the rough uneven structure and the fine uneven structure of the stamper are formed (the surface of the stamper) is made to face the transparent substrate. Next, the filled active energy ray-curable composition is irradiated with active energy rays (heat rays such as visible rays, ultraviolet rays, electron beams, plasma, infrared rays) from a high-pressure mercury lamp or metal halide lamp through a transparent substrate. Then, the active energy ray-curable composition is cured. Thereafter, the stamper is peeled off. As a result, an article having a rough concavo-convex structure and a fine concavo-convex structure formed of a cured product of the active energy ray-curable composition is obtained on the surface of the transparent substrate. At this time, if necessary, the active energy ray may be irradiated again after the stamper is peeled off.
The irradiation amount of an active energy ray should just be the energy amount which hardening progresses, and is 100-10000mJ / cm < ² > normally.

The material of the transparent substrate may be any material that does not significantly inhibit the irradiation of active energy rays. For example, polyethylene terephthalate (PET), methyl methacrylate (co) polymer, polycarbonate, styrene (co) polymer, methyl methacrylate -Styrene copolymer, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, polyester, polyamide, polyimide, polyether sulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polyurethane, Examples thereof include cycloolefin polymer, glass, quartz, and quartz.
The shape of the transparent substrate can be appropriately selected depending on the article to be produced. For example, in the case of an antireflection article such as an antireflection film, a sheet form or a film form is preferable.
The surface of the transparent substrate may be subjected to, for example, various coatings, corona discharge treatment, etc. in order to improve adhesion to the active energy ray-curable composition, antistatic properties, scratch resistance, weather resistance, etc. Good.

  The active energy ray-curable composition appropriately includes a monomer, oligomer, or reactive polymer having a radical polymerizable bond and / or a cationic polymerizable bond in the molecule, and may include a non-reactive polymer. Moreover, an active energy ray sol-gel reactive composition may be sufficient.

Examples of the monomer having a radical polymerizable bond include the following.
Monofunctional monomer: (meth) acrylate derivative (methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, sec-butyl (meth) Acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, alkyl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl ( (Meth) acrylate, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, allyl (meth) acrylate Relate, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, etc.), (meth) acrylic acid, (meth) acrylonitrile, styrene Derivatives (styrene, α-methylstyrene, etc.), (meth) acrylamide derivatives ((meth) acrylamide, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, etc.) and the like.

  Bifunctional monomer: ethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, isocyanuric acid ethylene oxide modified di (meth) acrylate, triethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, Neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,5-pentanediol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, polybutylene glycol di ( (Meth) acrylate, 2,2-bis (4- (meth) acryloxypolyethoxyphenyl) propane, 2,2-bis (4- (meth) acryloxyethoxyphenyl) propane, 2,2-bis (4- ( 3- (meta) Acryloxy-2-hydroxypropoxy) phenyl) propane, 1,2-bis (3- (meth) acryloxy-2-hydroxypropoxy) ethane, 1,4-bis (3- (meth) acryloxy-2-hydroxypropoxy) butane , Dimethylol tricyclodecane di (meth) acrylate, ethylene oxide adduct di (meth) acrylate of bisphenol A, propylene oxide adduct di (meth) acrylate of bisphenol A, neopentyl glycol di (meth) acrylate of hydroxypivalate, Divinylbenzene, methylenebisacrylamide, etc.

Trifunctional monomer: pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethylene oxide modified tri (meth) acrylate, trimethylolpropane propylene oxide modified triacrylate, trimethylolpropane ethylene oxide modified triacrylate , Isocyanuric acid ethylene oxide modified tri (meth) acrylate and the like.
Multifunctional monomer: Succinic acid / trimethylolethane / acrylic acid condensation reaction mixture, dipentaerystol hexa (meth) acrylate, dipentaerystol penta (meth) acrylate, ditrimethylolpropane tetraacrylate, tetramethylolmethanetetra ( (Meth) acrylate and the like.
Bifunctional or higher urethane acrylate, bifunctional or higher polyester acrylate, etc.
As the monomer having a radical polymerizable bond, one type may be used alone, or two or more types may be used in combination.

Examples of the monomer having a cationic polymerizable bond include monomers having an epoxy group, an oxetanyl group, an oxazolyl group, a vinyloxy group, and the like. Among these, a monomer having an epoxy group is particularly preferable.
Examples of oligomers and reactive polymers include unsaturated polyesters (condensates of unsaturated dicarboxylic acids and polyhydric alcohols), polyester (meth) acrylates, polyether (meth) acrylates, polyol (meth) acrylates, and epoxy (meth) ) Acrylate, urethane (meth) acrylate, cationic polymerization type epoxy compound, homopolymer or copolymer of the above-mentioned monomers having a radical polymerizable bond in the side chain.
Non-reactive polymers include acrylic resins, styrene resins, polyurethane resins, cellulose resins, polyvinyl butyral resins, polyester resins, thermoplastic elastomers, and the like.

  Examples of the active energy ray sol-gel reactive composition include alkoxysilane compounds and alkylsilicate compounds.

Examples of the alkoxysilane compound include those represented by R _x Si (OR ′) _y . R and R ′ represent an alkyl group having 1 to 10 carbon atoms, and x and y are integers satisfying the relationship of x + y = 4.
Specifically, tetramethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, methyltriethoxysilane, methyl Examples include tripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, trimethylmethoxysilane, trimethylpropoxysilane, and trimethylbutoxysilane.

_{Examples of the} alkyl silicate compound include those represented by R ¹ O [Si (OR ³ ) (OR ⁴ ) O] _z R ² . R ^{1 to} R ⁴ each represent an alkyl group having 1 to 5 carbon atoms, and z represents an integer of 3 to 20.
Specific examples include methyl silicate, ethyl silicate, isopropyl silicate, n-propyl silicate, n-butyl silicate, n-pentyl silicate, acetyl silicate and the like.

  The active energy ray-curable composition usually contains a polymerization initiator for curing. A well-known thing can be used as a polymerization initiator.

  When utilizing photoreaction, photoinitiators include, for example, carbonyl compounds (benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl, benzophenone, p-methoxybenzophenone, 2,2-di- Ethoxyacetophenone, α, α-dimethoxy-α-phenylacetophenone, methylphenylglyoxylate, ethylphenylglyoxylate, 4,4′-bis (dimethylamino) benzophenone, 2-hydroxy-2-methyl-1-phenylpropane -1-one), sulfur compounds (tetramethylthiuram monosulfide, tetramethylthiuram disulfide, etc.), 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoyldi Butoxy phosphine oxide and the like. A photoinitiator may be used individually by 1 type and may use 2 or more types together.

  When using an electron beam curing reaction, examples of the polymerization initiator include benzophenone, 4,4-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophenone, methyl orthobenzoylbenzoate, 4-phenylbenzophenone, t- Butylanthraquinone, 2-ethylanthraquinone, thioxanthone (2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, etc.), acetophenone (diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1- ON, benzyldimethyl ketal, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino- -(4-morpholinophenyl) -butanone etc.), benzoin ether (benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether etc.), acylphosphine oxide (2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, etc.), methylbenzoylformate, 1,7-bisacridini Examples include luheptane and 9-phenylacridine. A polymerization initiator may be used individually by 1 type, and may use 2 or more types together.

  When a thermal reaction is used, examples of the thermal polymerization initiator include organic peroxides (methyl ethyl ketone peroxide, benzoyl peroxide, dicumyl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, tert-butyl peroxide). Oxyoctoate, t-butylperoxybenzoate, lauroyl peroxide, etc.), azo compounds (azobisisobutyronitrile, etc.), N, N-dimethylaniline, N, N-dimethyl-p -The redox polymerization initiator etc. which combined amines, such as toluidine, are mentioned.

  The addition amount of the polymerization initiator is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the active energy ray-curable composition. If the addition amount is 0.1 parts by mass or more, the polymerization tends to proceed. If the addition amount is 10 parts by mass or less, the obtained cured product will not be colored or the mechanical strength will not be reduced.

  In addition to those described above, the active energy ray-curable composition includes an antistatic agent, a release agent, a leveling agent, a slip agent, an ultraviolet absorber, an antioxidant, a stabilizer, and fluorine for improving antifouling properties. Additives such as compounds, fine particles, a small amount of solvent, and the like may be added.

  The article thus manufactured has a transfer surface on which a fine concavo-convex structure composed of a plurality of pores formed on the surface of a stamper is transferred in a relationship between a key hole and a key. In addition, there are drop holes formed by dropping the intermetallic compound on the surface of the stamper. Therefore, such an article has an antireflection function by a plurality of fine convex portions (moth eye structure) formed by transferring fine pores, and a plurality of relatively large plurality of formed drop holes are transferred. The convex portion (coarse concavo-convex structure) slightly increases haze, and macro unevenness and color unevenness on the transfer surface are not noticeable.

Such an article can be expected to be used as an optical article such as an antireflection article, an optical waveguide, a relief hologram, a lens, a polarization separation element, and a crystal device, and in particular, an antireflection film, an antireflection film, and an antireflection of a three-dimensional shape. Suitable for use as an anti-reflective article such as a body.
Examples of antireflection articles include image display devices (liquid crystal display devices, plasma display panels, electroluminescence displays, cathode ray tube display devices, etc.), solar cell protective plates, transparent substrates for transparent electrodes, lenses, show windows, exhibitions, etc. Used for cases, meter panels, meter covers, lighting front plates, glasses surfaces, etc.
When used in an image display device, a film may be attached on the outermost surface, or may be directly formed on a material that forms the outermost surface, or may be formed on a front plate. In particular, in the case of an antireflection film that is directly attached to the outermost surface of a display that has little distance from the image plane, the haze at the level in the present invention is suitable because it has little influence on the sharpness of the image.

  In the case of the antireflection article, the period of the convex part is a period equal to or less than the wavelength of visible light, and the height of the convex part is preferably 50 nm or more, and preferably 100 nm or more. Further, the aspect ratio (height / cycle) of the convex portion is preferably 1.0 to 4.0, preferably 1.3 to 3.5, more preferably 1.8 to 3.5, and 2.0 to 3 0.0 is most preferred. If the aspect ratio is 1.0 or more, the reflectivity is sufficiently low, and the incident angle dependency and wavelength dependency are sufficiently small. If the aspect ratio is greater than 4.0, the mechanical strength of the transfer surface tends to decrease.

The reflectance of the article is preferably 2% or less, and more preferably 1% or less. Further, the wavelength dependency (difference between the maximum reflectance and the minimum reflectance) is preferably 1.5% or less, more preferably 1.0% or less, and further preferably 0.5% or less.
The haze of the article is preferably more than 0.8% and less than 8%, and more preferably 0.9 to 4.0%. When the haze is 0.8% or less, it is easy to visually recognize macro unevenness and color unevenness generated on the transfer surface. When the haze is 8% or more, the sharpness of the image is lowered when used in an image display device.

When the article is an antireflection film, for example, it can be used by directly pasting on the image surface of an image display device (liquid crystal display device, plasma display panel, electroluminescence display, cathode tube display device, etc.).
When the article is a three-dimensional antireflection body, an antireflection body is manufactured in advance using a transparent substrate having a shape according to the application, and this can be used as a member constituting the surface of the object. it can.

  Applications other than the optical application of articles include cell culture sheets, super water-repellent films, super hydrophilic films and the like. The super water-repellent film can be used by being attached to windows of automobiles, railway vehicles, etc., and can be used for preventing snow and ice from headlamps and lighting.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

(Area of intermetallic compound)
After polishing the processed surface of the aluminum base to a mirror surface, a reflected electron image of 10 or more fields of view is photographed using a scanning electron microscope (manufactured by JEOL Ltd., JCM-5700), and an automatic image processing analysis system (manufactured by Nireco Corp.). , LUZEX-AP), the area of the intermetallic compound in the field of view was determined, and this was divided by the area of the field of view to calculate the ratio of the total area of the intermetallic compound to the area of the work surface (100%).

(Average diameter of intermetallic compound)
The surface to be machined of the aluminum substrate is mirror-polished, then observed with a scanning electron microscope, and the area of 100 or more intermetallic compounds is determined by an automatic image processing analysis system (manufactured by Nireco Corporation, LUZEX-AP). The equivalent diameter was calculated and the average value was determined.

(Arithmetic mean roughness Ra)
The arithmetic average roughness Ra of the processed surface of the aluminum substrate was measured using a surface roughness measuring instrument (Surf Test SJ-401, manufactured by Mitutoyo Corporation) in accordance with JIS B0601-2001.

(Average crystal grain size)
The surface to be processed of the aluminum substrate is polished and etched, and then observed with an optical microscope. The area of 100 or more crystal grains is obtained by image analysis software (Image-Pro PLUS), and the equivalent circle diameter is calculated for each. The average value was obtained.

(Thickness of the first oxide film)
Platinum is vapor-deposited for 1 minute on the longitudinal section or surface of the aluminum substrate immediately after the first oxide film forming step (a), and the acceleration voltage is measured using a field emission scanning electron microscope (JSM-7400F, manufactured by JEOL Ltd.). : The oxide film was observed under the condition of 3.00 kV, the thickness of the oxide film was measured at 10 locations, and the average value was obtained.

(Dimension of stamper pore)
Platinum is vapor-deposited for 1 minute on the longitudinal section or surface of the stamper on which the anodized alumina is formed, and the acceleration voltage is set to 3.00 kV using a field emission scanning electron microscope (JSM-7400F, manufactured by JEOL Ltd.). Then, the anodized alumina was observed, and the period of the pores, the depth of the pores, and the bottom diameter of the pores (diameter at a depth of 98% from the surface) were measured at 10 locations, and the average value was obtained.

(Dimension of convex part of article)
Platinum is vapor-deposited for 5 minutes on the longitudinal section or surface of the article on which the transfer surface is formed, and the transfer surface is subjected to an acceleration voltage of 3.00 kV using a field emission scanning electron microscope (JSM-7400F, manufactured by JEOL Ltd.). Were observed, and the period of the convex part and the height of the convex part were measured at ten locations, and the average value was obtained.

(Reflectance of articles)
The back surface (the surface opposite to the transfer surface) of the article was roughened with sandpaper and then painted with a matte black spray. Using a spectrophotometer (U-4000, manufactured by Hitachi, Ltd.), the relative reflectance of the transfer surface of the article was measured in the range of incident angle: 5 ° and wavelength: 380-780 nm.

(Haze of goods)
The haze of the article was measured using a haze meter corresponding to JIS K7361.

(Appearance of goods)
The article was held under a fluorescent lamp, and the transfer surface of the article was observed while changing the viewing angle from 10 ° to 90 °, and evaluated according to the following criteria.
(Macro unevenness)
○: Cannot be confirmed visually.
X: A level | step difference can be confirmed visually.
(Color unevenness)
A: Cannot be confirmed visually.
○: Can hardly be confirmed visually.
X: It can confirm slightly visually.

[Forging example 1]
Hot forging + cold forging:
2S, 1 / 2U, 2S, 1 / 2U forged by 1000t press machine with aluminum ingot heated to 430 ° C, 2S, 1 / 2U, 2S, reheated to 430 ° C. The 1 / 2U hot forging was performed again, gradually cooled to room temperature, and 2S, 1 / 2U, 2S, and 1 / 2U cold forging were further performed. When the material exceeded 200 ° C. during cold forging, forging was interrupted and forging was performed again after cooling.

[Forging example 2]
Hot forging:
With the aluminum ingot heated to 430 ° C, hot forging of 1.5S, 0.65U, 1.5S, 0.65U, 1.5S, 0.65U was performed with a 1000t press, and the temperature was returned to 430 ° C. In the heated state, hot forging at 1.5S, 0.65U, 1.5S, and 0.65U was performed again.

[Example 1]
An aluminum ingot having a purity of 99.90% was forged according to Forging Example 1, and then heat treated at 325 ° C. for 2 hours. The obtained aluminum substrate was cut into an outer diameter: 200 mm, an inner diameter: 155 mm, and a length: 350 mm, and this was electropolished in a perchloric acid / ethanol mixed solution (volume ratio = 1/4) to obtain a work surface. A cylindrical aluminum base material having an arithmetic average roughness Ra of 0.03 μm and an average crystal grain size of 100 μm was obtained. The physical properties of the aluminum base are shown in Table 1.
Subsequently, the aluminum substrate was anodized in a 0.3 M oxalic acid aqueous solution under conditions of bath temperature: 16 ° C. and direct current: 40 V to form an oxide film (thickness: 3 μm) (step ( a)). The formed oxide film was once dissolved and removed in a 6% by mass phosphoric acid and 1.8% by mass chromic acid mixed aqueous solution (step (b)), and then again under the same conditions as in step (a). Anodized for 2 seconds to form an oxide film (step (c)). Thereafter, the substrate was immersed in a 5% by mass phosphoric acid aqueous solution (30 ° C.) for 8 minutes, and subjected to a pore diameter expansion treatment (step (d)) for expanding the pores of the oxide film. Further, step (c) and step (d) were repeated, and these were performed a total of five times (step (e)) to obtain a stamper. The shape of the stamper is shown in Table 2.
As shown in FIG. 2, a roll-shaped stamper having a fine concavo-convex structure in which a tapered hole having a substantially conical shape with a period p: 100 nm, a depth Dep: 190 nm, and a pore bottom diameter: 40 nm was formed. . When the fine uneven structure on the surface of the stamper was visually confirmed, macro unevenness at the grain boundaries could not be confirmed.
Subsequently, the stamper was dipped in a 0.1% by mass solution of a mold release agent (manufactured by Daikin Industries, Ltd., OPTOOL DSX (trade name)) for 10 minutes, and air-dried for 24 hours for release treatment. This was installed in the manufacturing apparatus 30 shown in FIG. 5, and articles were manufactured as follows.

As shown in FIG. 5, a roll-shaped stamper 31 was fitted into a shaft made of carbon steel for mechanical structure having a cooling water flow path provided therein. Subsequently, an active energy ray-curable composition 33 having the following composition is passed through a supply nozzle from a tank 35 at room temperature through a transparent nozzle 32 (polyethylene terephthalate (PET) film) nipped between a nip roll 36 and a stamper 31. , Manufactured by Toyobo Co., Ltd., A4300 (trade name)). At this time, the nipping was performed by the nip roll 36 in which the nip pressure was adjusted by the pneumatic cylinder 37, and the active energy ray-curable composition 33 was also filled in the pores (recesses) of the stamper 31.
While the stamper 31 is rotated at a speed of 7.0 m / min, the active energy ray-curable composition 33 is sandwiched between the stamper 31 and the transparent substrate 32, and ultraviolet rays are emitted from a 240 W / cm ultraviolet irradiation device 38. After irradiation, the active energy ray-curable composition 33 was cured and shaped, and then peeled off from the stamper 31 by a peeling roll 39 to obtain an article 34 (transparent sheet) having a fine concavo-convex structure on the surface. The obtained results are shown in Table 3.

(Active energy ray-curable composition)
Trimethylolethane / acrylic acid / succinic anhydride condensation ester: 45 parts by mass,
Hexanediol diacrylate: 45 parts by mass
X-22-21602 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd .: 10 parts by mass,
Irgacure 184 (trade name) manufactured by Ciba Specialty Chemicals: 2.7 parts by mass,
Irgacure 819 (trade name) manufactured by Ciba Specialty Chemicals: 0.18 parts by mass.

[Example 2]
A 99.80% pure aluminum rolled plate (thickness: 0.5 mm) was cut into 50 mm square, and this was electropolished in a perchloric acid / ethanol mixed solution (volume ratio = 1/4) to obtain an aluminum substrate. (Table 1).
Next, a stamper was manufactured in the same manner as in Example 1 (Table 2), and a mold release treatment was performed.
The active energy ray-curable composition of Example 1 is placed on the surface of the release-treated stamper, and a PET film (A4300 (trade name) manufactured by Toyobo Co., Ltd.), which is a transparent substrate, is further laminated thereon to activate the stamper. With the energy ray curable composition in contact with the stamper, the active energy ray curable composition was cured by irradiating ultraviolet rays with an energy of 3200 mJ / cm ² through the PET film.
Thereafter, the article made of the transparent substrate and the cured product was peeled from the stamper. The obtained results are shown in Table 3.

[Comparative Example 1]
An aluminum ingot having a purity of 99.97% was forged according to Forging Example 2 and then heat treated at 380 ° C. for 2 hours. The obtained aluminum substrate was cut into A4 size and thickness 10 mm, and mirror-finished in the same manner as in Example 1 to obtain an aluminum substrate (Table 1).
A stamper was manufactured in the same manner as in Example 1 except that the anodic oxidation in the step (c) was 32 seconds (Table 2), and a mold release treatment was performed.
The active energy ray-curable composition of Example 1 is placed on the surface of the release-treated stamper, and a PET film (A4300 (trade name) manufactured by Toyobo Co., Ltd.), which is a transparent substrate, is further laminated thereon to activate the stamper. With the energy ray curable composition in contact with the stamper, the active energy ray curable composition was cured by irradiating ultraviolet rays with an energy of 3200 mJ / cm ² through the PET film.
Thereafter, the article made of the transparent substrate and the cured product was peeled from the stamper. The obtained results are shown in Table 3.

[Comparative Example 2]
A 99.30% pure aluminum rolled plate (thickness: 0.5 mm) was cut into 50 mm square, and this was electropolished in a perchloric acid / ethanol mixed solution (volume ratio = 1/4) to obtain an aluminum substrate. (Table 1).
Next, a stamper was manufactured in the same manner as in Example 1 (Table 2), and a mold release treatment was performed.
The active energy ray-curable composition of Example 1 is placed on the surface of the release-treated stamper, and a PET film (A4300 (trade name) manufactured by Toyobo Co., Ltd.), which is a transparent substrate, is further laminated thereon to activate the stamper. With the energy ray curable composition in contact with the stamper, the active energy ray curable composition was cured by irradiating ultraviolet rays with an energy of 3200 mJ / cm ² through the PET film.
Thereafter, the article made of the transparent substrate and the cured product was peeled from the stamper. The obtained results are shown in Table 3.

  The stamper obtained by the production method of the present invention is useful for producing an article for optical use such as an antireflection article.

DESCRIPTION OF SYMBOLS 10 Aluminum base material 11 Pore 12 Oxide film 13 Pore generation | occurrence | production point 14 Pore 15 Oxide film 20 Stamper 30 Manufacturing apparatus 31 Stamper 32 Transparent base material 33 Active energy ray curable composition 34 Article 35 Tank 36 Nip roll 37 Pneumatic cylinder 38 Ultraviolet irradiation device 39 Peeling roll

Claims (8)

An aluminum substrate having a processed surface on which the fine concavo-convex structure is formed, which is used for manufacturing a stamper having a fine concavo-convex structure on a surface,
The workpiece surface has a plurality of intermetallic compounds exposed on the workpiece surface,
The total area of the intermetallic compounds exposed on the work surface is greater than 0.14% and 0.7% or less with respect to the area (100%) of the work surface;
The aluminum base material for stamper manufacture whose arithmetic average roughness Ra of the said to-be-processed surface is 0.05 micrometer or less.   The aluminum base material for stamper manufacture according to claim 1, wherein an average diameter of the intermetallic compound exposed on the work surface is 0.5 to 3.0 µm.   In the aluminum substrate (100% by mass), the silicon content is 0.1% by mass or less, the iron content is 0.4% by mass or less, and the copper content is 0.3% by mass or less. The aluminum base material for stamper manufacture according to claim 1 or 2, wherein   The aluminum base material for stamper manufacture according to any one of claims 1 to 3, which has been forged.   The aluminum base material for stamper manufacture according to any one of claims 1 to 4, wherein the average crystal grain size is 1 mm or less.   A fine concavo-convex structure comprising a plurality of pores with a period of 400 nm or less is formed on the work surface by anodizing the work surface of the aluminum base material for stamper production according to any one of claims 1 to 5. And a method for producing a stamper, wherein the intermetallic compound is removed to form a rough uneven structure on the work surface.   The method for manufacturing a stamper according to claim 6, wherein an aspect ratio (depth / cycle) of the pores is 1.0 or more. A first oxide film forming step (a) of anodizing the surface to be processed of the aluminum base material in an electrolyte under a constant voltage to form an oxide film on the surface to be processed;
Removing the oxide film, and forming an anodized pore generation point on the surface to be processed (b);
The processed surface of the aluminum base material on which the pore generation point is formed is anodized again under a constant voltage in an electrolytic solution, and an oxide film having pores corresponding to the pore generation point is formed on the processed surface. A second oxide film forming step (c) formed on
The method for manufacturing a stamper according to claim 6, further comprising: a pore diameter expansion processing step (d) for expanding the diameter of the pores.

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