US20130112567A1

US20130112567A1 - Apparatus for manufacturing mold for nanoimprinting and method of manufacturing mold for nanoimprinting

Info

Publication number: US20130112567A1
Application number: US13/810,206
Authority: US
Inventors: Satoru Ozawa; Masatoshi Kamata; Katsuhiro Kojima; Tomohiro Masaki
Original assignee: Mitsubishi Rayon Co Ltd
Current assignee: Mitsubishi Rayon Co Ltd
Priority date: 2010-07-26
Filing date: 2011-07-21
Publication date: 2013-05-09
Also published as: KR101489096B1; WO2012014774A1; CN103025923A; KR20130033412A; JPWO2012014774A1; TWI508872B; TW201210852A; JP5796491B2; CN103025923B

Abstract

An apparatus for manufacturing a mold for nanoimprinting and a method of manufacturing a mold for nanoimprinting are provided. The apparatus for manufacturing the mold for nanoimprinting performs an anodic oxidation treatment to an aluminum substrate with an electrolytic solution and is characterized in that at least a material of a surface of a portion contacting with the electrolytic solution is a metal or an alloy thereof, having an eluted amount of 0.2 ppm/cm²or less per unit area when immersed in 80 ml of the electrolytic solution at room temperature for 450 hours. The method of manufacturing the mold for nanoimprinting is characterized in using the apparatus for manufacturing the mold for nanoimprinting to carry out the anodic oxidation treatment. The manufacturing apparatus and manufacturing method of the invention suppress metal elution into the electrolytic solution during the anodic oxidation treatment.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to an apparatus for manufacturing a mold for nanoimprinting and a method of manufacturing a mold having porous structures on a surface thereof for nanoimprinting.
This application claims the benefit of Japanese Patent Application No. 2010-167139 filed on Jul. 26, 2010, which is hereby incorporated by reference herein.
2. Description of Related Art
In recent years, it is known that the products with the uneven microstructure (the porous structures) thereon present antireflection effects, lotus effects and the like, whereas the period of the uneven microstructure is equal to or less than the wavelength of visible light. Particularly, because the refractive indices keep increasing continuously from the refractive index of the air to the refractive index of the material of the product, the uneven structure, so-called the moth-eye-structure, becomes an effective antireflection means.
As a method of forming an uneven microstructure on the surface of the product, the method of using a mold having an inversion structure of the aforementioned uneven microstructure formed on the surface thereof to transfer the aforementioned uneven microstructure to the surface of the product (nanoimprint method) has attracted attention.
As a method for manufacturing a mold for nanoimprinting, the method of making an inversion structure of the uneven microstructure on the surface of the substrate by lithography is common.
In recent years, from the viewpoints of easy area enlargement and simple production, a method of forming anodized alumina, of which the surface has a plurality of pores (concavity), by using an electrolytic solution to perform anodic oxidation treatment to the aluminum substrate has been proposed (Patent literature 1, for example).
In addition, a method of using an anodic oxidation treatment apparatus having an anodizing tank made of a plastic, such as polyvinyl chloride and the like, to perform the anodic oxidation treatment has been proposed (for example, Patent literature 2).

REFERENCES LIST

Patent Literature

Patent literature 1: Japanese Patent Publication No. 2010-5841
Patent literature 2: Japanese Patent Publication No. 2007-224369

SUMMARY OF THE INVENTION

Problems that the Invention is to Solve

However, in the method of forming an anodized alumina as described in Patent literature 1, the members, such as heat exchangers, the anodizing tank and the like, constituted to form the anodic oxidation treatment apparatus, are generally made of corrosion-resistant metals, such as niobium or titanium and the like, or coated with these metals.
Nevertheless, in the anodic oxidation treatment, it is common to use an acidic electrolytic solution, such as the aqueous solution of oxalic acid, etc., and thus there is a problem of corrosion for the portions of the anodizing tank in contact with the electrolytic solution when the anodic oxidation treatment is repeatedly used. When corrosion occurs in the anodizing tank, metals, such as titanium or niobium and the like, are eluted into the electrolytic solution, and the electrolytic solution tends to be colored. As a result, the eluted metals are attached to the obtained mold and become the contamination to the mold or extraneous substances during nanoimprinting.
In the method described in Patent literature 2, since the anodizing tank, etc., made of plastic is used, it presents resistance to the electrolytic solution, but it is inferior in durability because the strength is weak. In addition, there are problems of reduced heat exchange efficiency or temperature control, etc., when using plastic for coating the surface of the heat exchanger.
Therefore, when performing the anodic oxidation treatment to the aluminum substrate, it is demanded to use the anodic oxidation treatment apparatus having the members, such as the heat exchanger, the anodizing tank, etc., made of a metal that is not eluted into the electrolytic solution.
The invention has been made in view of the aforementioned circumstances, and the invention provides an apparatus for manufacturing a mold for nanoimprinting capable of suppressing the elution of metal into the electrolytic solution when the anodic oxidation treatment is performed, and provides a method of manufacturing a mold for nanoimprinting.

Means for Solving the Problems

The invention relates to the following.
(1) An apparatus for manufacturing a mold for nanoimprinting, which is an apparatus for manufacturing a mold for nanoimprinting by performing an anodic oxidation treatment to an aluminum substrate in an electrolytic solution, and is characterized in that at least a material of a surface of a portion in contact with the electrolytic solution is a metal of the following criteria or an alloy thereof.
[Criteria]
An eluted amount per unit area of the metal immersed in 80 mL of the electrolytic solution for 450 hours at room temperature is 0.2 ppm/cm²or less.
(2) The apparatus for manufacturing the mold for nanoimprinting according to (1) is characterized in that the electrolytic solution is oxalic acid.
(3) The apparatus for manufacturing the mold for nanoimprinting according to (2) is characterized in that the material of the surface of the portion in contact with the electrolytic solution is zirconium or an alloy thereof.
(4) The apparatus for manufacturing the mold for nanoimprinting according to (2) is characterized in that the material of the surface of the portion in contact with the electrolytic solution is tantalum or an alloy thereof.
(5) The apparatus for manufacturing the mold for nanoimprinting according to (1) is characterized in that the electrolytic solution is sulfuric acid.
(6) The apparatus for manufacturing the mold for nanoimprinting according to (5) is characterized in that the material of the surface of the portion in contact with the electrolytic solution is niobium or an alloy thereof.
(7) The apparatus for manufacturing the mold for nanoimprinting according to (5) is characterized in that the material of the surface of the portion in contact with the electrolytic solution is tantalum or an alloy thereof.
(8) A method of manufacturing a mold for nanoimprinting, which performs an anodic oxidation treatment to an aluminum substrate in an electrolytic solution to form a porous structure on a surface of the mold for nanoimprinting, is characterized in using an apparatus for manufacturing a mold for nanoimprinting to perform the anodic oxidation treatment, wherein a material of a surface of a portion in contact with the electrolytic solution at least is a metal of the following criteria or an alloy thereof
[Criteria]
An eluted amount per unit area of the metal immersed in 80 mL of the electrolytic solution for 450 hours at room temperature is 0.2 ppm/cm²or less.
(9) The method of manufacturing the mold for nanoimprinting according to (8) is characterized in that the electrolytic solution is oxalic acid.
(10) The method of manufacturing the mold for nanoimprinting according to (9) is characterized in that the material of the surface of the portion in contact with the electrolytic solution is zirconium or an alloy thereof.
(11) The method of manufacturing the mold for nanoimprinting according to (9) is characterized in that the material of the surface of the portion in contact with the electrolytic solution is tantalum or an alloy thereof.
(12) The method of manufacturing the mold for nanoimprinting according to (8) is characterized in that the electrolytic solution is sulfuric acid.
(13) The method of manufacturing the mold for nanoimprinting according to (12) is characterized in that the material of the surface of the portion in contact with the electrolytic solution is niobium or an alloy thereof.
(14) The method of manufacturing the mold for nanoimprinting according to (12) is characterized in that the material of the surface of the portion in contact with the electrolytic solution is tantalum or an alloy thereof.

Effect of the Invention

According to the invention, an apparatus for manufacturing a mold for nanoimprinting capable of suppressing the elution of the metal into the electrolytic solution when the anodic oxidation treatment is performed, and a method of manufacturing a mold for nanoimprinting may be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view showing an example of an apparatus for manufacturing a mold for nanoimprinting of this invention.

FIG. 2 is a schematic cross-sectional view showing an example of a manufacturing process of a mold having anodized alumina on a surface thereof.

FIG. 3 is a block diagram showing an example of an apparatus for manufacturing a product having a porous structure on a surface thereof.

FIG. 4 is a schematic cross-sectional view showing an example of a product having a porous structure on a surface thereof.

FIG. 5 is a view of a cross-section of the anodized alumina after an pole oxidation treatment, which is taken by an electronic microscope.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, the invention is described in detail.
In this specification, “(meth) acrylate” represents acrylate or methacrylate. The “active energy ray” represents visible light, ultraviolet light, electron beam, plasma, or heat ray (infrared ray, etc.).
An apparatus for manufacturing a mold for nanoimprinting of the invention is an apparatus for performing an anodic oxidation treatment to an aluminum substrate to form nano uneven structures used for nanoimprinting on the surface of the aluminum substrate.
“Room temperature” in the invention means 25° C.
In the invention, the “eluted amount per unit area of the metal immersed in 80 mL of the electrolytic solution for 450 hours at room temperature is 0.2 ppm/cm²or less” indicates that the eluted amount per unit area of a metal piece that has been immersed in 80 mL of the electrolytic solution at the room temperature of 25° C. for 450 hours is within the aforementioned range.
[Apparatus for Manufacturing a Mold for Nanoimprinting]
FIG. 1 is a schematic cross-sectional view showing one example of an apparatus for manufacturing a mold for nanoimprinting of the invention.
The apparatus for manufacturing the mold for nanoimprinting 10 includes an anodizing tank 12, filled with the electrolytic solution; a top cover 16 covering the top of the anodizing tank 12 and peripherally formed with a trough 14 for receiving the electrolytic solution overflown from the anodizing tank 12; a storage tank 18 for temporarily storing the electrolytic solution; a downward flow path 20 for downward flowing the electrolytic solution received by the trough 14 to the storage tank 18; a backward flow path 24 for backward flowing the electrolytic solution stored in the storage tank 18 to a supply port 22 formed near the bottom of the anodizing tank 12, which is at a side lower than the aluminum substrate 30; a pump 26, provided in the middle of the backward flow path 24; a current plate 28 for adjusting the flow of the electrolytic solution that is discharged from the supply port 22; a shaft 34, inserted into the cylindrical and hollow aluminum substrate 30 that functions as an anode, with a central shaft 32 being held horizontally; a driving device (not shown) for rotating the shaft 34 and the aluminum substrate 30 using the central shaft 32 (i.e. the central shaft of the aluminum substrate 30) of the shaft 34 as a rotation axis; two cathode plates 36, arranged facing each other with the aluminum substrate 30 therebetween; a power source 38, electrically connected to the two cathode plates 36 and the center shaft 32 of the shaft 34, and a temperature control means 40 for adjusting the temperature of the electrolytic solution in the storage tank 18.
The pump 26 provides a flow of the electrolytic solution from the storage tank 18, through the backward flow path 24 and toward the anodizing tank 12, and drives the electrolytic solution to be discharged from the supply port 22, thereby forming a flow of the electrolytic solution rising from the bottom of the anodizing tank 12 to its top.
The current plate 28 is a plate member with two or more through holes formed therein to adjust the flow of the electrolytic solution that is discharged from the supply port 22 to substantially uniformly rise from the entire bottom of the anodizing tank 12. The current plate 28 is disposed between the aluminum substrate 30 and the supply port 22 in a way that a surface thereof is substantially horizontal.
The driving device (not shown) is a motor, etc., connected to the central shaft 32 of the shaft 34 through a ring-shaped chain or gear member and the like (not shown).
The two cathode plates 36 are metal plates disposed parallel to the central shaft of the aluminum substrate 30 with the aluminum substrate 30 sandwiched in the horizontal direction, and the two cathode plates 36 are spaced apart from the aluminum substrate 30 with a gap and disposed oppositely.
The temperature control means 40 may be exemplified as heat exchangers using water, oil and the like as a heat medium and electric heaters and the like.
Conventionally, as a material of the members, such as heat exchangers, the anodizing tank, etc., provided in the apparatus for manufacturing the mold for nanoimprinting, a plastic such as polyvinyl chloride is used, but there is a problem of poor durability. In addition, if plastic is used to coat the surface of the heat exchanger, for example, problems of reduced heat exchange efficiency and temperature control exist.
In addition, even if the members, such as heat exchangers, the anodizing tank, etc., made of a corrosion-resistant metal, such as titanium and the like, are used, there is a problem of corrosion for the portion of the anodizing tank in contact with the electrolytic solution when repeatedly used. When corrosion occurs in the portion in contact with the electrolytic solution, the metal, such as titanium and the like, is eluted into the electrolytic solution, and the electrolytic solution tends to be colored. It is considered that such problems are caused by the formation of complexes from the eluted metal with the acid component of the electrolytic solution.
The coloration of the electrolytic solution makes the eluted metal be attached to the obtained mold and become causes of the contamination to the mold or extraneous substances during nanoimprinting.
Additionally, if a large amount of the metal is eluted into the electrolytic solution, the formed anodic oxide film may not grow into the desired shape, which has been revealed by the study of the inventors. By inhibiting the elution of the metal into the electrolytic solution, the mold for nanoimprinting situation with the anodic oxide film of the desired shape may be produced efficiently. Further, if the width of the mold becomes wider, the apparatus to produce the aforementioned mold also becomes larger, thus with greater portion of the metal member in contact with the electrolytic solution. From the viewpoint of stable production of the mold for nanoimprinting, the eluted amount of the metal piece made of metal materials used for the metal members is 0.2 ppm/cm²or less, preferably 0.1 ppm/cm²or less when immersed in 80 mL of the electrolytic solution. If the eluted amount is greater than 0.2 ppm/cm², the eluted metal adversely affects the formation of the anodic oxide film. Furthermore, metal deposits may be detected in a molded body transferred from the mold that is made by the apparatus including the members made of the metal having the eluted amount greater than 0.2 ppm/cm².
From the viewpoint of stable production of the mold for nanoimprinting, the eluted amount of each of the metal members in 80 mL of the electrolytic solution is preferably 0-0.2 ppm/cm², more preferably 0-0.1 ppm/cm².
When using, for example, oxalic acid as the electrolytic solution for the apparatus for manufacturing the mold for nanoimprinting of the invention, the material of the surface of at least a portion in contact with the electrolytic solution may be exemplified as tantalum or an alloy thereof, or zirconium or the alloy thereof In addition, when using, for example, sulfuric acid as the electrolytic solution, the material of the surface of at least a portion in contact with the electrolytic solution may be exemplified as tantalum or an alloy thereof, or niobium or the alloy thereof Therefore, the apparatus for manufacturing the mold for nanoimprinting of the invention affords excellent resistance to the electrolytic solution, and the elution of the metal is suppressed.
In general, titanium, tantalum, zirconium, and niobium are materials having acid resistance and corrosion resistance; however, such resistance is highly dependent on the type of the acid. In addition, depending on the applications, different performances are required. Particularly, under the circumstances of manufacturing the mold for nanoimprinting by anodic oxidation, as the shape of the mold has to be greatly controlled to produce an accurate molded body, performances of the materials of general acid resistance and corrosion resistance may be insufficient. As a result of the intensive studies of the inventors, it becomes clear that a predetermined metal is particularly preferable in the case of manufacturing the mold for nanoimprinting by anodic oxidation. Furthermore, it becomes clear that the different metals are preferred depending on the type of the electrolytic solution used for anodic oxidation.
For the apparatus for manufacturing the mold for nanoimprinting of the invention, at least the material of the surface of the portion in contact with the electrolytic solution is a metal having specific physical properties as described above (hereinafter referred as “specific metal”) or alloys thereof. Particularly, a portion of the member that is likely to be in contact with the electrolytic solution is preferably the specific metal or an alloy thereof
That is, the specific metal of the invention is a metal having the eluted amount in 80 mL of the electrolytic solution equal to or less than 0.2 ppm/cm². When oxalic acid, for example, is used as the electrolytic solution, tantalum or zirconium may be exemplified as the specific metal. In addition, when using, for example, sulfuric acid as the electrolytic solution, tantalum or niobium may be exemplified as the specific metal.
Herein, the “portion (that is) in contact with the electrolytic solution” may be exemplified, as shown in FIG. 1, for example, as the anodizing tank 12, the top cover 16, the storage tank 18, the downward flow path 20, the supply port 22, the backward flow path 24, and the inner side of the pump 26, or the current plate 28, the central shaft 32, the shaft 34, the cathode plates 36, and the side surface of the temperature control means 40.
In particular, the portion of the temperature control means 40, such as heat exchangers, in contact with the electrolytic solution is preferably formed with the specific metal or an alloy thereof. The temperature control means 40 is used to control the temperature of the electrolytic solution. However, if resin is used to form the temperature control means 40, there is possibility that thermal conductivity is inferior and unable to precisely control the concentration of the electrolytic solution.
Further, in the invention, for the portion that is in contact with the electrolytic solution, the specific metal or alloys thereof may be used to coat the surface of the members made of other materials. For coating, the thickness of the layer made of the specific metal or alloys thereof is preferable 1 μm or more, more preferably 10 μm or more. If the thickness is equal to or more than 1 μm, the effect of suppressing the elution of the metal into the electrolytic solution is likely to be sustained. Moreover, if the member is damaged, the inside material is difficult to be exposed.
Preferred alloys are oxides of the specific metal or those obtained by adding required amounts of elements such as tungsten, silicon, carbon and the like into the specific metal. Specifically, they may be exemplified as zirconium oxide, zirconium tungstate, zircon, tantalum tungsten, tantalum silicon alloys, tantalum carbide, niobium silicon alloys, and lithium niobate, etc.
For the apparatus for manufacturing the mold for nanoimprinting of the invention as described above, since at least the material of the surface of the portion in contact with the electrolytic solution is the specific metal or the alloys thereof, the metal eluted into the electrolytic solution can be suppressed when the anodic oxidation treatment is performed, and thus the coloration of the electrolytic solution is avoided.
The apparatus for manufacturing the mold for nanoimprinting of the invention is suitable as an apparatus for manufacturing a mold having porous structures formed on the surface thereof for nanoimprinting and can produce a mold for nanoimprinting with less deposition of the metal. Further, in the electrolytic solution that has metal dissolved therein, it may be difficult to form the anodic oxide film of the predetermined shape. However, by suppressing the elution of the metal into the electrolytic solution, the anodic oxide film of the desired shape can be produced efficiently. Moreover, less contamination is found in the mold for nanoimprinting obtained by the apparatus for manufacturing the mold for nanoimprinting of the invention, and the incorporation of extraneous substances during nanoimprinting can be suppressed.
In addition, since metal is used for the material of the surface of the portion that is in contact with the electrolytic solution of the apparatus for manufacturing the mold for nanoimprinting of the invention, the durability can be ensured. Furthermore, compared with the heat exchanger coated with plastic, the temperature control or heat exchange rate of the heat exchanger is excellent, so that the anodic oxidation treatment can be efficiently performed to the aluminum substrate.
[Manufacturing Method of the Mold for Nanoimprinting]
The manufacturing method of a mold for nanoimprinting (hereinafter referred to as simply “mold”) of the invention is to use the apparatus for manufacturing the mold for nanoimprinting, of which at least the material of the surface of the portion in contact with the electrolytic solution is the specific metal or an alloy thereof, to perform the anodic oxidation treatment to the aluminum substrate with the electrolytic solution. Therefore, excellent resistance to the electrolytic solution is maintained, and the elution of the metal is suppressed.
The method for manufacturing the mold for nanoimprinting of the invention includes using the electrolytic solution to perform the anodic oxidation treatment to the aluminum substrate to form a porous structure having two or more pores on the surface of the aluminum substrate. Herein, the aforementioned manufacturing method includes performing the anodic oxidation treatment in the apparatus, in which at least the material of the surface of the portion in contact with the electrolytic solution is a metal or an alloy thereof, and the eluted amount per unit area of the metal when immersed in 80 mL of the electrolytic solution for 450 hours at room temperature is 0.2 ppm/cm²or less.
The manufacturing method of the mold of the invention uses the apparatus for manufacturing the mold for nanoimprinting, of which at least the material of the surface of the portion in contact with the electrolytic solution is the specific metal or an alloy thereof, to perform the anodic oxidation treatment to the aluminum substrate with the electrolytic solution, without particular limitations for other steps. However, preferably the following steps (a)-(f) are included.
Step (a) anodizing the aluminum substrate under a constant voltage in an electrolytic solution to form an oxide film on the surface of the aluminum substrate.
Step (b) removing the oxide film to form the pore generation spots of the anodic oxidation on the surface of the aluminum substrate.
Step (c) anodizing the aluminum substrate in the electrolytic solution again to form an oxide film having pores at the pore generation spots.
Step (d) expanding the diameter of the pore.
Step (e) after step (d), anodizing in the electrolytic solution again.
Step (f) repeating steps (d) and (e), to obtain the mold with anodized alumina having two or more pores pores formed on the surface of the aluminum substrate.
The steps are explained as follows.
Moreover, when performing the anodic oxidation in steps (a), (c) and (e), the apparatus for manufacturing the mold for nanoimprinting, of which at least the material of the surface of the portion in contact with the electrolytic solution is the specific metal or an alloy thereof, is used.
Step (a):
As shown in FIG. 2, the aluminum substrate 30 is anodized to form the oxide film 44 having pores 42.
The shape of the aluminum substrate may be exemplified as a roll, a cylindrical tube, a flat plate, a sheet and the like.
Further, in order to smooth the surface state of the aluminum substrate, the aluminum substrate is preferably polished by mechanical polishing, buffing, chemical polishing, electrolytic polishing (etching process) or the like. In addition, since the oil used in processing the aluminum substrate into the predetermined shape may be attached to the aluminum substrate, it is preferred that the aluminum substrate is pre-degreased before the anodic oxidation.
The purity of the aluminum is preferably 99% or more, more preferably 99.5% or more, and 99.8% or more is particularly preferred. If the purity of the aluminum is low, when anodizing the aluminum, uneven structure large enough to scatter visible light can be formed due to segregation of impurities, and the regularity of the pores obtained by the anodic oxidation may be reduced.
For the electrolytic solution, an aqueous solution of oxalic acid, sulfuric acid, and the like may be used.
The electrolytic solution may be used singly or used in combination of two or more kinds.
When using an aqueous solution of oxalic acid as the electrolytic solution:
The concentration of oxalic acid is preferably equal to or less than 0.7M. When the concentration of oxalic acid is more than 0.7M, the current value is too high, which results in rough surface of the oxide film. When the formation voltage is 30-60V, the anodized alumina having a high pore regularity with an average interval of 100 nm is obtained. If the formation voltage is higher or lower than this range, the pore regularity is likely to decline.
The temperature of the electrolytic solution is preferably equal to or less than 60° C., and more preferably equal to or less than 45° C. When the temperature of the electrolytic solution exceeds 60° C., a phenomenon called “burning” may occur, the pores may be damaged, and the regularity of the pores may be disturbed as the surface is melted.
When using an aqueous solution of sulfuric acid as the electrolytic solution:
The concentration of sulfuric acid is preferably equal to or less than 0.7M. When the concentration of sulfuric acid is more than 0.7M, the current value becomes too high and it is impossible to maintain a constant voltage.
When the formation voltage is 25-30V, the anodized alumina having high pore regularity of an average interval of 63 nm is obtained. If the formation voltage is higher or lower than this range, the pore regularity is likely to decline.
The temperature of the electrolytic solution is preferably equal to or less than 30° C., and more preferably equal to or less than 20° C. When the temperature of the electrolytic solution exceeds 30° C., the phenomenon called “burning” may occur, the pores may be damaged, and the regularity of the pores may be disturbed as the surface is melted.
When compared with the case of using sulfuric acid as the electrolytic solution, in the case of using oxalic acid as the electrolytic solution, it is easy to obtain the anodized alumina having pores arranged at relatively large intervals of 100 nm or more. When using the anodized alumina as the mold, it is difficult to ensure the mold releasability with small pore intervals. Hence, using oxalic acid as the electrolytic solution is preferred.
Step (b):
As shown in FIG. 2, once the oxide film 44 is removed and pore generation spots 46 of the anodic oxidation are obtained. By doing so, the regularity of the pores is improved.
The method for removing the oxide film may be exemplified by a method of dissolving and removing the oxide film in a solution that is capable of selectively dissolving the oxide film but not dissolving aluminum. Examples of such a solution include a mixture solution of chromic acid/phosphoric acid and the like.
Step (c):
As shown in FIG. 2, the aluminum substrate 30, from which the oxide film is removed, is again anodized so as to form the oxide film 44 having cylindrical pores 42.
The anodic oxidation may be carried out under the same conditions as recited in the step (a). Deeper pores can be formed by performing the anodic oxidation for a longer period of time.
Step (d):
As shown in FIG. 2, a process for expanding the diameter of the pores 42 (hereinafter, referred to as pore expanding process) is performed. The pore expanding process is a process to expand the diameter of the pores, which is obtained by performing anodic oxidation, by immersing the pores in the solution that dissolves the oxide film. Examples of the solution include the aqueous solution of phosphoric acid of about 5 mass %, and the like.
The diameter of the pores can be enlarged if the pore expanding process is performed for a longer period of time.
In step (d), it is preferable to use an apparatus for the pore expanding process, wherein at least the material of the surface of the portion that is in contact with the dissolving solution is the specific metal or the alloy as described above. By using such an apparatus, the elution of the metal into the dissolving solution during the pore expanding process may be suppressed. As a result, it is possible to prevent the coloration of the dissolving solution or the adhesion of metal to the mold. Thus, the contamination of the mold or the incorporation of extraneous substances during nanoimprinting can be suppressed more effectively.
In addition, since metal is used for the material of the portion that is in contact with the dissolving solution, the durability of the apparatus for pore expanding process can be ensured.
Step (e):
As shown in FIG. 2, the anodic oxidation is performed again to form the cylindrical pores 42 downward from bottoms thereof and further to farm the cylindrical pores 42 with a small diameter.
The anodic oxidation may be carried out under the same conditions as recited in the step (a). Deeper pores can be formed by performing the anodic oxidation for a longer period of time.
Step (f):
As shown in FIG. 2, the pore expanding process of Step (d) and the anodic oxidation of Step (e) are repetitively performed to form the oxide film 44 having the pores 42, (each of the pores 42 has an opening with a diameter continuously diminishing from the opening in a depth direction). Hence, the mold 48 with the aluminum substrate 30 having the anodized alumina (the porous anodic oxide film, alumite) formed on the surface thereof is obtained. Preferably, the whole process is finished with the Step (d).
The repetition times of the foregoing processes are preferably three times or more in total, more preferably 5 times or more. If the foregoing processes are performed for two times or less, the diameter of the pores is not continuously reduced, and the reflectivity reduction effect of the porous structure (moth-eye structure) which is formed by using the anodized alumina having such pores may be insufficient.
The shape of the pores 42 may be exemplified as substantially a cone shape, a pyramid shape, a column shape, etc. The cone shape and the pyramid shape, etc., of which the pore cross-sectional area that is perpendicular to the depth direction continuously decreases from the top in the depth direction, are preferred.
The average interval of the pores 42 is equal to or less than the wavelength of visible light, that is, 400 nm. The average interval of the pores 42 is preferably equal to or more than 20 nm.
The average interval of the pores 42 is preferably 20 nm or more and 400 nm or less, more preferably 50 nm or more and 300 nm or less, and particularly preferably 90 nm or more and 250 nm or less.
The average interval of the pores 42 is observed by using the electronic microscope to measure 50 intervals between the adjacent pores 42 (distance from the center of the pore 42 to the center of the adjacent pore 42) and determine the average value by averaging the values of the 50 intervals.
When the average interval is 100 nm, the depth of the pores 42 is preferably 80-500 nm, more preferably 120-400 nm, and particularly preferably 150-300 nm.
The depth of the pores 42 is obtained by measuring the distance between the bottom of the pores 42 and the top part of the convex portion existing between the pores 42 when observed at a magnification of 30,000 times by the observe electronic microscope.
The aspect ratio of the pores 42 (the pore depth/the average interval between the pores) is preferably 0.8- to 5.0, more preferably 1.2- to 4.0, and particularly preferably 1.5- to 3.0.
In the invention, the mold body 48 obtained in step (f) may be used directly as a mold, or may alternatively be treated with a release agent to the surface of the mold body 48 at the side formed with the porous structure.
As a release agent, the release agent having a functional group capable of forming a chemical bond with anodized alumina of the aluminum substrate is preferred. More specifically, silicone resins, fluoro resins, fluoro-compounds, and the like are exemplified. From the viewpoints of excellent releasability and excellent adhesion toward the mold body, the fluoro-compound having a silanol group or a hydrolyzable silyl group is preferred, and the fluoro-compound having a hydrolyzable silyl group is particularly preferred among them.
Examples of commercially available fluoro-compounds having a hydrolyzable silyl group may be fluoroalkylsilane, KBM-7803 (manufactured by Shin-Etsu Chemical Co., Ltd.), “OPTOOL” series (manufactured by Daikin Industries, Ltd.) and Novec EGC-1720 (manufactured by Sumitomo 3M Corporation) and the like.
As a treatment method using the release agent, the following methods (I) and (II) may be exemplified, and from the viewpoint of treating evenly the surface of the mold body at the side formed with the porous structure with the release agent, method (I) is particularly preferred.
Method (I) is a method of immersing the mold in a dilute solution of the release agent.
Method (II) is a method of applying the release agent or the dilute solution thereof to the surface of the mold body at the side formed with the porous structure.
Method (I) is preferably the method having the following steps (g)-(l).
Step (g): washing the mold body with water.
Step (h): removing the water droplets attached to the surface of the mold body by blowing air into the mold body.
Step (i): immersing the mold body into the diluted solution that is obtained by diluting the fluoro-compound having a hydrolyzable silyl group with a solvent.
Step (j): withdrawing the immersed mold body from the solution slowly.
Step (k): if needed, heating and humidifying the mold body in the stage later than step (j).
Step (l): drying the mold body.
Step (g):
The agents (such as the aqueous solution of phosphoric acid used in the pore expanding process) used for fanning the porous structure and impurities (such as dust etc.) attached to the mold body are removed by water washing.
Step (h):
Air is blown into the mold body, so as to remove almost all water droplets visible to the naked eye.
Step (i):
As the solvent for dilution, any known solvent, such as fluorine-based solvents, alcohol-based solvents, etc., may be used. Among the foregoing, from the viewpoint of having the moderate volatility and wettability to apply the external release agent solution uniformly, the fluorine-based solvent is preferably. The fluorine-based solvent may be exemplified as hydrofluoropolyether, perfluorohexane, perfluoro methyl cyclohexane, perfluoro-1,3-dimethyl cyclohexane, dichloropentafluoropropane and the like.
In the diluted solution (100 mass %), the concentration of the fluoro-compound having a hydrolyzable silyl group is preferably 0.01 mass %-0.2 mass %.
The immersion time is preferably 1-30 minutes.
The immersion temperature is preferably 0-50° C.
Step (j):
When withdrawing the immersed mold body from the solution, it is preferred to use an electric pulling device to withdraw at a constant speed to reduce swing during withdrawing. By doing so, the uneven coating can be reduced.
The pulling speed is preferably 1 mm/sec-10 mm/sec.
Step (k):
In the stage latter than step (j), the mold body is left under heating and humidifying, the hydrolyzable silyl group of the fluoro-compound (mold release agent) is hydrolyzed into a silanol group, and the aforementioned silanol group sufficiently reacts with the hydroxyl groups on the surface of the mold body. Thus the fixability of the fluoro-compound is improved.
The heating temperature is preferably 40-100° C.
The humidity condition is preferably equal to or more than 85% relative humidity.
The standing time is preferably 10 minutes-1 day.
Step (l):
In the step of drying the mold body, the mold body may be air dried or compulsorily dried by heating in the dryer.
The drying temperature is preferably 30-150° C.
The drying time is preferably 5-300 minutes.
Whether the surface of the mold body has been treated with the release agent can be confirmed by measuring the water contact angle of the surface of the mold body. The water contact angle of the surface of the mold body that has been treated with the release agent is preferably equal to or larger than 60°, more preferably equal to or larger than 90°. If the water contact angle is equal to or larger than 60°, the surface of the mold body is well treated with the release agent, and the mold releasability is good.
For the method for manufacturing the mold of this invention as described above, the apparatus for manufacturing the mold for nanoimprinting having at least the material of the surface of the portion that is in contact with the dissolving solution being the specific metal or the alloy thereof is used. Therefore, the elution of the metal into the electrolytic solution during the anodic oxidation treatment may be suppressed. As a result, it is possible to prevent the coloration of the electrolytic solution or the adhesion of metal to the mold. Thus, the contamination of the mold or the incorporation of extraneous substances during nanoimprinting can be suppressed.
In addition, according to the invention, since metal is used for the material of the surface of the portion that is in contact with the electrolytic solution, the durability of the apparatus for manufacturing the mold for nanoimprinting can be ensured. Furthermore, when compared with the heat exchanger coated with plastic, the temperature control or heat exchange rate of the heat exchanger is excellent, so that the mold for nanoimprinting formed with the anodized alumina of the desired shape can be efficiently produced.
[Product With the Porous Structure on the Surface Thereof]
The product having the porous structure on the surface thereof is produced, for example, by using the manufacturing apparatus shown in FIG. 3 based on the following processes.
The active energy ray curable resin composition, from the tank 52, is supplied between a roll mold 50 having the porous structure (not shown) formed thereon and the strip film 72 that moves along the surface of the roll mold 50.
The active energy ray curable resin composition and the film 72 are nipped between the roll mold 50 and the nip rolls 56 with a nip pressure adjusted by a pneumatic cylinder 54, so that the active energy ray curable resin composition is distributed uniformly between the film 72 and the roll mold 50 and at the same time filled into the concave of the porous structure of the roll mold 50.
From the active energy ray irradiation device 58, which is disposed below the roll mold 50, the active energy ray is irradiated to the active energy ray curable resin composition through the film 72 to cure the active energy ray curable resin composition, so as to form a cured resin layer 74, onto which the porous structure on the surface of the roll mold 50 is transferred.
The film 72 with the cured resin layer 74 formed thereon is peeled off from the roll mold 50 by the peeling roll 60, so as to obtain a product 70 as shown in FIG. 4.
The active energy ray irradiation apparatus 58 may preferably be a high-pressure mercury lamp, a metal halide lamp, the fusion lamp, etc. and the irradiation energy in this case is preferably 100-10000 mJ/cm².
The film 72 is a light transparent film. The material of the film 72 may be exemplified as acrylic resin, polycarbonate, styrene resin, polyester, cellulose resin(triacetyl cellulose, etc.), polyolefins, alicyclic polyolefins and the like.
The cured resin layer 74 is a film made of a cured article of the active energy ray curable resin composition, having the porous structure on the surface. In the case of using a mold of anodized alumina, the porous structure on the surface of the product 70, which has been formed by transferring the porous structure on the surface of anodized alumina, includes two or more protrusions 76 constituted by the cured article of the active energy ray curable resin composition.
As the porous structure, the so-called moth-eye structure with two or more protrusions of substantially conical or pyramid shape arranged as multi-lined is preferred. The moth-eye structure with the interval between the protrusions equal to or less than the wavelength of visible light is known to be effective means for antireflection because the refractive indices are increased continuously from the refractive index of air to the refractive index of the material.
The average interval between the protrusions is equal to or less than the wavelength of visible light, i.e. equal to or less than 400 nm. When the protrusions are formed by using the mold of this invention, the average interval between the protrusions is about 100 nm, preferably 200 nm or less, and particularly preferably 150 nm or less.
From the viewpoint of simple construction of the protrusions, the average interval between the protrusions is preferably equal to or more than 20 nm.
The range of the average interval between the protrusions is preferably 20 nm-400 nm, more preferably 50 nm-300 nm, and more preferably 90 nm-250 nm.
The average interval between the protrusions is obtained by measuring 50 values of the interval (the distance from the center of one protrusion to the center of the adjacent protrusion) between adjacent protrusions by the electronic microscope and then calculating the average of these values.
When the average interval is 100 nm, the height of the protrusions is preferably 80 nm-500 nm, more preferably 120 nm-400 nm, and particularly preferably 150 nm-300 nm. When the height of the protrusions is equal to or more than 80 nm, the reflectivity becomes sufficiently low and the wavelength dependence of the reflectivity is small. When the height of the protrusions is equal to or less than 500 nm, the abrasion resistance of the protrusions is favorable.
The height of the protrusions is obtained by measuring the distance between the top part of the protrusions and the bottom of the concave between the protrusions when observed at a magnification of 30,000 times by the electronic microscope.
The aspect ratio (height of the protrusion/the average interval between the protrusions) of the protrusions is preferably 0.8-5.0, more preferably 1.2-4.0, and particularly preferably 1.5-3.0. When the aspect ratio is equal to or more than 1.0, the reflectivity becomes sufficiently low and the wavelength dependence of the reflectivity is small. When the aspect ratio of the protrusion is equal to or less than 5.0, the abrasion resistance of the protrusions is favorable.
Each of the protrusions has a shape that the cross-sectional area thereof in a direction perpendicular to the height direction continuously increases from the surface in the depth direction. That is, the preferred shape of the cross-section of the protrusions in the height direction may be a triangular shape, a trapezoid, a bell shape, etc.
The difference between the refractive index of the cured resin layer 74 and the refractive index of the film 72 is preferably 0.2 or less, more preferably 0.1 or less, particularly preferably 0.05 or less. When the refractive index difference is equal to or less than 0.2, the reflection at the interface between the cured resin layer 74 and the film 72 is suppressed.
In the case that the surface has the porous structure thereon, super water repellency over the surface can be obtained due to the lotus effect if the surface is made of a hydrophobic material. Moreover, super hydrophilicity can be obtained over the surface if the surface is made of a hydrophilic material.
When the material of the cured resin layer 74 is the hydrophobic material, the water contact angle of the surface of the porous structure is preferably equal to or larger than 90°, more preferably equal to or larger than 110°, and particularly preferably equal to or larger than 120°. If the water contact angle is equal to or larger than 90°, the water stain is difficult to be attached and the stain-proof property is sufficiently presented. In addition, as the water is difficult to be attached, it is expected to prevent ice-accretion.
When the material of the cured resin layer 74 is the hydrophobic material, the water contact angle of the surface of the uneven microstructure is preferably equal to or larger than 90° and equal to or smaller than 180°, more preferably equal to or larger than 110° and equal to or smaller than 180°, and particularly preferably equal to or larger than 120° and equal to or smaller than 180°.
When the material of the cured resin layer 74 is the hydrophilic material, the water contact angle of the surface of the porous structure is preferably 25° or less, more preferably 23° or less, and particularly preferably 21° or less. If the water contact angle is equal to or less than 25°, the stain attached to the surface may be easily washed away by water and the surface is difficult to have oil stains attached thereto, so that the stain-proof property is sufficiently presented. In order to suppress the increase of reflectivity that occurs with the deformation of the porous structure caused by water absorption of the cured resin layer 74, the water contact angle is preferably equal to or larger than 3°.
When the material of the cured resin layer 74 is the hydrophilic material, the water contact angle of the surface of the uneven microstructure is preferably equal to or larger than 3° and equal to or smaller than 30°, more preferably equal to or larger than 3° and equal to or smaller than 23°, and particularly preferably equal to or larger than 3° and equal to or smaller than 21°.
[Active Energy Ray Curable Resin Composition]
The active energy ray curable resin composition includes a polymerizable compound and a polymerization initiator. Known compounds can be used as the polymerizable compound, such as monomers, oligomers or reactive polymers having free radical polymerization bond(s) and/or cationic polymerization bond(s), etc. in molecule. Further, the active energy ray curable resin composition may include non-reactive polymers and active energy ray sol-gel reactive composition.
On the other hand, as the polymerization initiator, known photopolymerization initiators, thermal polymerization initiators, polymerization initiators using the electron beam curing reaction, and the like may be exemplified.
In order to maintain the water contact angle of the surface of the porous structure of the cured resin layer 74 to be 90° or more, it is preferred to use a composition including a fluorine-containing compound or a silicone compound as the active energy ray curable resin composition capable of forming the hydrophobic material.
In addition, in order to maintain the water contact angle of the surface of the porous structure of the cured resin layer 74 to be 25° or less, it is preferred to use a composition at least including the hydrophilic monomers as the active energy ray curable resin composition capable of forming the hydrophilic material. In view of the scratch resistance or the water resistance of the cured resin layer, the composition including the crosslinking reactive polyfunctional monomers is preferred. In addition, the hydrophilic monomer may be the same as the crosslinking reactive polyfunctional monomers (i.e. hydrophilic polyfunctional monomers). In addition, the active energy ray curable resin composition may include other monomers.
[Uses]
The uses of the product 70 may be exemplified as antireflection products, anti-fog products, stain-proof products, and water-repellent products. Specifically, the product may be exemplified as the antireflection for the displays, the meter cover of automobiles, the mirror of automobiles, the window of automobiles, emission enhancing elements for organic or inorganic electroluminescent, solar cell members and the like.
Moreover, the product having the porous structure on the surface thereof is not limited to the exemplified product 70. For example, the porous structure may be formed directly on the film 72 without forming the cured resin layer 74. However, from the viewpoint of using the roll mold 50 to efficiently form the porous structure, it is preferred to form the porous structure on the surface of the cured resin layer 74.

EXAMPLES

Test Examples

The test examples are described as follows.
In the following Test Examples 1-1-1-4 and Test Examples 2-1-2-4, in order to confirm the resistance of the metal of the members, such as the anodizing tank and the heat exchanger(s), in the apparatus for manufacturing the mold for nanoimprinting to the electrolytic solution, or the resistance of the metal of the member in the pore enlarging processing apparatus to the dissolving solution, typically used corrosion-resistant tantalum (Ta), zirconium (Zr), titanium (Ti) and niobium (Nb) were used and immersed in the electrolytic solution or the dissolving solution (hereinafter collectively referred to as “processing solution”), and the concentration of the metal eluted in the processing solution was measured.
In addition, in this test, an aqueous solution of oxalic acid was used as the electrolytic solution in the anodic oxidation treatment and an aqueous solution of phosphoric acid is used as the dissolving solution in the pore enlarging process. The concentrations were the actual concentrations used in the anodic oxidation treatment and the pore enlarging process, wherein the concentration of the aqueous solution of oxalic acid was adjusted to 2.7 mass % and the aqueous solution of sulfuric acid was adjusted to 15 mass %.
Further, when the metal piece was immersed in the processing solution, the higher the temperature of the processing solution is, the greater the promoting effect is for the elution of the metal. However, this test example was carried out at room temperature. And “room temperature” used herein refers to 25° C.
In addition, ICP emission spectrometry mass spectrometer (high-frequency inductively coupled mass spectrometer), capable of measuring the concentrations of metal with high accuracy in a short period of time, was used to measure the concentrations of metals.

Test Example 1-1>

At room temperature, a test piece of tantalum simple substance (5.0 cm×2.5 cm, 1mm thick) was immersed in the aqueous solution of 2.7 mass % oxalic acid which served as the processing solution for 450 hours. Then, the metal piece was removed from the processing solution and the concentrations of the eluted metal in the processing solution were measured as follows.
First, 1 mL of the processing solution after removing the metal piece was collected, transferred to a 50 mL volumetric flask and diluted with 50 mL of pure water, so as to prepare the measurement samples.
Then, using CID high-frequency plasma emission spectrometer analysis apparatus (“IRIS Advantage AP” manufactured by Thermo Fisher Scientific) as ICP emission spectrometry mass spectrometer, the most sensitive wavelength for each metal sample was selected to measure the concentrations of the metals in the measurement samples. The results are shown in Table 1.

Test Examples 1-2-1-4 (Examples 1-4 in Table 1), Test Examples 2-1-2-4 Comparative Examples 1-4 in Table 1

Except for changing the types of the processing solutions and metals as shown in Table 1, the same method as used in Test Example 1-1 was used to prepare the measurement samples, and the concentrations of the metals were determined. Furthermore, as an aqueous solution of sulfuric acid, an aqueous solution of 15 mass % of sulfuric acid was used. The results are shown in Table 1. In addition, in Table 1, the eluted amount “-” means the concentration of the metal is below the test limits.

TABLE 1

			Eluted	Eluted amount
	Electrolytic		amount	per unit area
Example	soln.	Metal	(ppm)	(ppm/cm²)

1	oxalic acid	Ta	0.16	0.006
2	oxalic acid	Zr	—	—
3	sulfuric acid	Ta	—	—
4	sulfuric acid	Nb	2.6	0.1
Comparative
Example
1	oxalic acid	Nb	220	8.3
2	oxalic acid	Ti	1200	45.3
3	sulfuric acid	Zr	6.4	0.24
4	sulfuric acid	Ti	2500	94.3

As apparent from Table 1, for the aqueous solution of oxalic acid, the eluted amount per unit area of tantalum and zirconium is less than 0.2 ppm. Further, for the aqueous solution of sulfuric acid, the eluted amount per unit area of niobium and zirconium is less than 0.2 ppm.
Thus, in the apparatus for manufacturing the mold for nanoimprinting using oxalic acid as the electrolytic solution, zirconium and tantalum are suitable as the material for the portion that is in contact with the electrolytic solution, as it can be inferred that the elution of the metal into the electrolytic solution can be suppressed when the anodic oxidation treatment is performed. In addition, in the apparatus for manufacturing the mold for nanoimprinting using sulfuric acid as the electrolytic solution, niobium and tantalum are suitable as the material for the portion that is in contact with the electrolytic solution, as it can be inferred that the elution of the metal into the electrolytic solution can be suppressed when the anodic oxidation treatment is performed.
High metal concentrations of niobium and titanium are found in the oxalic acid solution, and these metals are easily eluted in the processing solution. Similarly, high metal concentrations of zirconium and titanium are found in the sulfuric acid solution, and these metals are easily eluted out.
Therefore, titanium and niobium, in the apparatus for manufacturing the mold for nanoimprinting using oxalic acid as the electrolytic solution for the anodic oxidation treatment, are not suitable as the material of the portion in contact with the electrolytic solution. In addition, titanium and zirconium, in the apparatus for manufacturing the mold for nanoimprinting using sulfuric acid as the electrolytic solution for the anodic oxidation treatment, are not suitable as the material of the portion in contact with the electrolytic solution.
In fact, a solution obtained by diluting the oxalic acid solution that was immersed with the above-mentioned metal pieces 3-fold with a solution of 2.7 mass % oxalic acid was used as the electrolytic solution for performing the anodic oxidation of aluminum.
An aluminum plate (99.99% purity) of 50 mm×50 mm×0.3 mm thick, used as the aluminum substrate, was electropolished in a mixed solution of perchlorate/ethanol (volume ratio 1/4).
For the above aluminum plate, the electrolytic solutions obtained by diluting the oxalic acid solutions that were immersed with the above-mentioned metal pieces 3-fold with a solution of 2.7 mass % oxalic acid were used to perform anodic oxidation for 6 hours, at 40V DC, under the temperature condition of 16° C. A part of the pore alumina after the anodic oxidation treatment was cut, and platinum was deposited on the cross-section for one minute. The field emission shape scanning electronic microscope (manufactured by JEOL, JSM-7400F) was used under the conditions of the accelerating voltage 3.00 kV to observe the cross-section and measure the thickness of the oxide films (FIG. 5).
As shown in FIG. 5, the anodized alumina using the oxalic acid solution immersed with tantalum or zirconium was almost the same as the case when anodic oxidation was performed using a solution of oxalic acid immediately after the adjustment. When compared with the case of using an aqueous solution of oxalic acid immediately after the adjustment, for the anodized alumina using the aqueous solution of oxalic acid immersed with titanium, the anodic oxide film was too thin to form an anodic oxide film having a desired shape and thickness. Niobium float was confirmed in the aqueous solution of oxalic acid immersed with niobium, and the suspending substance was deposited on the anodized alumina.
Titanium was used to fabricate the heat exchanger of the apparatus for manufacturing the mold for nanoimprinting, and the mold was prepared by the following methods.

Test Example 3

An aluminum plate (99.99% purity) of 50 mm×50 mm×0.3 mm thickness, used as the aluminum substrate, was electropolished in a mixed solution of perchlorate/ethanol (volume ratio 1/4).
Step (a):
For the aluminum plate, in an aqueous solution of 0.3M oxalic acid, 40V DC, anodic oxidation was carried out for 6 hours under the temperature condition of 16° C.
Step (b):
The aluminum plate formed with the oxide film was immersed in an aqueous mixed solution of 6 mass % phosphoric acid/1.8 mass % chromic acid for 3 hours, so that the oxide film was removed.
Step (c):
For the aluminum plate, in an aqueous solution of 0.3M oxalic acid, 40V DC, anodic oxidation was carried out for 30 seconds under the temperature condition of 16 ° C.
Step (d):
The aluminum plate formed with the oxide film was immersed in an aqueous solution of 5 mass % phosphoric acid for 8 minutes at 32° C., so as to perform the pore expanding process.
Step (e):
For the aluminum plate, in an aqueous solution of 0.3M oxalic acid, 40V DC, anodic oxidation was carried out for 30 seconds under the temperature condition of 16° C.
Step (f):
The Step (d) and Step (e) were repeatedly performed for 4 times and finally Step (d) was performed, so as to obtain the mold body of anodized alumina having the substantially cone-shaped pores with the average interval of the pores being 100 nm and the pore depth being 240 nm formed on the surface thereof.
Step (g):
The shower was used to lightly wash away the phosphoric acid solution on the surface of the mold body, and the mold body was then immersed in the flowing water for 10 minutes.
Step (h):
The air gun was used to blow the air to the mold body so as to remove the water droplets attached on the surface of the mold body.
Step (i):
The mold body was immersed in a diluted solution of 0.1 mass % OPTOOL
DSX (manufactured by Daikin Chemicals Sales Co., Ltd.) by the diluent of HD-ZV (manufactured by Harves Co., Ltd.) for 10 minutes at the room temperature for 10 minutes.
Step (j):
The mold body was withdrawn out at 3 mm/sec from the diluted solution.
Step (l):
The mold body was air dried for 15 minutes and the mold body treated with the release agent was obtained.
Moreover, the apparatus for manufacturing the mold for nanoimprinting having a heat exchanger made of titanium was used for performing the anodic oxidation treatment in steps (a), step (c), and step (e).
In addition, the pores of the mold were measured by the following methods.
A part of the anodized alumina was cut, and platinum was deposited on the cross-section for one minute. The field emission shape scanning electronic microscope (manufactured by JEOL, JSM-7400F) was used under the conditions of the accelerating voltage 3.00 kV to observe the cross-section and measure the interval and depth of the pores. The measurements were respectively performed at 50 points and the mean values were determined.
In Test Example 3, the test was to verify the electrolytic solution after the fabrication of the mold (oxalic acid solution), and yellowing occurred. The titanium concentration in the electrolytic solution was measured in the same manner as in Test Example 1-1, and the result was 0.4 ppm. It is considered that the reason of yellowing was because titanium was eluted into the electrolytic solution to form the complex with oxalic acid.
In addition, the result of performing nanoimprinting using the obtained mold indicates that extraneous substance containing titanium was detected from the surface of the transferred film.

INDUSTRIAL APPLICATIONS

The apparatus for manufacturing the mold for nanoimprinting and the method of manufacturing the mold for nanoimprinting of the invention are capable of suppressing the elution of the metal into the electrolytic solution when the anodic oxidation treatment is performed, and accordingly the anodic oxide film of the desired shape can be formed efficiently. Hence, they are useful in efficient production of antireflection products, anti-fog products, stain-proof products, and water-repellent products.

DESCRIPTION OF THE SYMBOLS

10: apparatus for manufacturing the mold for nanoimprinting
12: anodizing tank
30: aluminum substrate
40: temperature control means
42: pore
44: oxide film (anodic alumina)
50: roll mold

Claims

1. An apparatus for manufacturing a mold for nanoimprinting, which performs an anodic oxidation treatment to an aluminum substrate in an electrolytic solution, and is characterized in that at least a material of a surface of a portion in contact with the electrolytic solution is a metal of the following criteria or an alloy of the metal of the following criteria:

an eluted amount of the metal per unit area when immersed in 80 mL of the electrolytic solution for 450 hours at room temperature is 0.2 ppm/cm²or less.

2. The apparatus of claim 1, wherein the electrolytic solution is oxalic acid.

3. The apparatus of claim 2, wherein the material of the surface of the portion in contact with the electrolytic solution is zirconium or an alloy thereof.

4. The apparatus of claim 2, wherein the material of the surface of the portion in contact with the electrolytic solution is tantalum or an alloy thereof

5. The apparatus of claim 1, wherein the electrolytic solution is sulfuric acid.

6. The apparatus of claim 5, wherein the material of the surface of the portion in contact with the electrolytic solution is niobium or an alloy thereof

7. The apparatus of claim 5, wherein the material of the surface of the portion in contact with the electrolytic solution is tantalum or an alloy thereof

8. A method of manufacturing a mold for nanoimprinting, which comprises performing an anodic oxidation treatment to an aluminum substrate in an electrolytic solution to form a porous structure on a surface of the mold by using an apparatus for manufacturing a mold for nanoimprinting to perform the anodic oxidation treatment, wherein at least a material of a surface of a portion of the apparatus in contact with the electrolytic solution is a metal of the following criteria or an alloy of the metal of the following criteria:

9. The method of claim 8, wherein the electrolytic solution is oxalic acid.

10. The method of claim 9, wherein the material of the surface of the portion in contact with the electrolytic solution is zirconium or an alloy thereof.

11. The method of claim 9, wherein the material of the surface of the portion in contact with the electrolytic solution is tantalum or an alloy thereof.

12. The method of claim 8, wherein the electrolytic solution is sulfuric acid.

13. The method of claim 12, wherein the material of the surface of the portion in contact with the electrolytic solution is niobium or an alloy thereof.

14. The method of claim 12, wherein the material of the surface of the portion in contact with the electrolytic solution is tantalum or an alloy thereof.