JP2012140001A - Mold and method for manufacturing the same, and method for manufacturing article which has minute unevenness structure in surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a mold which can form the oxidation films with few depth unevenness of a pore, even if the gap of the pore is ≥180 nm.SOLUTION: A method for manufacturing the mold 18 in which the oxidation film 14 having the pore 12 on the surface of the aluminum base material 10 includes: (a) a process to form an oxidation film 14 by anodizing a surface of the aluminum base material 10; (b) a process to remove the oxidation film 14 after the process (a); (c) a process to form the oxidation film 14 by anodizing the aluminum base material 10 by the voltage of less than 90% of the highest voltage applied in the process (a) after the process (b); (d) a process to expand a pore diameter of a pore 12 of the oxidation film 14 after the process (c); (e) a process to repeat the process (c) and the process (d)alternately.

Description

  The present invention relates to a mold having a fine concavo-convex structure consisting of a plurality of pores on the surface, a method for producing the mold, and a method for producing an article having a fine concavo-convex structure on the surface using the mold.

  In recent years, it has become possible to impart nanoscale fine concavo-convex structures to the surface of articles due to advances in microfabrication technology. The nanoscale fine concavo-convex structure has been developed for industrial use because, for example, special functions derived from the structure, such as an antireflection function called the moth-eye effect and a water repellent function called the Lotus effect, are manifested. .

  There are various techniques for imparting a fine relief structure to the surface of an article. Among these, the method of transferring the fine concavo-convex structure formed on the surface of the mold to the surface of the article body is suitable for industrial production because the fine concavo-convex structure can be imparted to the surface of the article with simple and few steps. In recent years, as a method for easily producing a mold having a fine concavo-convex structure on the surface, a method using an oxide film (anodized porous alumina) formed when an aluminum substrate is anodized has attracted attention (for example, Patent Document 1).

When an oxide film is used as a fine concavo-convex structure of a mold, a method of performing anodization in two stages in order to form pores suitable for a mold with little depth unevenness (hereinafter referred to as two in this specification). (Also referred to as a step oxidation method) is preferred. That is, the following steps (1) to (3) are sequentially performed to obtain pores suitable for the mold.
(1) A step of anodizing the surface of the aluminum substrate to form an oxide film without considering the depth of the pores.
(2) A step of removing a part or all of the oxide film formed in the step (1) to form a recess reflecting the shape of the bottom of the oxide film.
(3) A step of forming the pores having an arbitrary depth while maintaining the arrangement of the recesses generated in the step (2) by using the recesses as pore generation points and anodizing again.

  By the way, the space | interval of the pore in an oxide film becomes large depending on the applied voltage. That is, the interval between the pores can be controlled simply by changing the voltage applied by anodic oxidation. For example, in Patent Document 2, an oxide film having a pore interval of about 200 nm is formed by performing both anodization in step (1) and step (3) at 80V.

Japanese Patent No. 4460020 Japanese Patent No. 4368415

  Generally, in anodic oxidation, the higher the applied voltage, the higher the current density, making it difficult to control the thickness of the oxide film and the temperature of the electrolyte used for anodic oxidation. In order to apply a voltage in a high voltage range and make the pore depth uniform in the submicron region in step (3), it is necessary to closely examine the conditions of the oxide film formed in step (1). . For example, if the pores of the oxide film formed in step (1) are too irregularly arranged, the size of the pore generation points generated in step (2) varies, and as a result, step (3) This causes a local difference in the growth rate of the oxide film, which causes the depth unevenness and impairs the advantages of the two-stage oxidation method.

  In the example described in Patent Document 2, the concentration of the oxalic acid electrolyte is set low at 0.05 mol / L and the temperature is set low at 3 ° C. in the step (1). Under the conditions, since the size of the pore generation points generated in the step (2) varies, the depth of the pores formed in the step (3) is also non-uniform. It cannot be manufactured. In order to manufacture a mold with less unevenness of the depth of the pores, it is necessary to carry out the step (1) under the condition that the variation in the size of the pore generation points is reduced. For example, in the case of producing a mold having a pore interval of 180 nm or more using an oxalic acid electrolytic solution, in the step (1), after devising to increase the cooling efficiency of the aluminum substrate during anodization, It is necessary to apply a voltage of 90 V or higher without lowering the concentration or temperature of the electrolyte.

  However, in such a case, if the anodic oxidation in step (3) is carried out at the same voltage as in step (1) following the conventional two-stage oxidation method (for example, Patent Document 1), the growth of the oxide film is fast and the fineness is reduced. The unevenness of the hole depth becomes remarkable. In anti-reflective articles (anti-reflective coatings, etc.) obtained from molds with significant pore depth unevenness, the pore depth unevenness has an adverse effect on the performance of the article, for example, the reflectance curve varies depending on the measurement location. Effect.

  The present invention has been made in view of the above circumstances, and provides a method for producing a mold capable of forming an oxide film with little unevenness in the depth of pores even when the interval between pores is 180 nm or more.

  As a result of intensive studies, the inventors set the voltage in the second and subsequent anodic oxidation to a value lower than the maximum voltage in the first anodic oxidation, so that the pore spacing is 180 nm or more, The inventors have found that an oxide film with little pore depth unevenness can be formed, and have completed the present invention.

That is, the mold manufacturing method of the present invention is a method of manufacturing a mold in which an oxide film having a plurality of pores is formed on the surface of an aluminum substrate, and includes the following steps (a) to (e): It is characterized by having.
(A) A step of anodizing the surface of the aluminum substrate to form an oxide film.
(B) A step of removing the oxide film formed in the step (a).
(C) A step of forming an oxide film having a plurality of pores after the step (b) by anodizing the aluminum substrate at a voltage less than 90% of the maximum voltage applied in the step (a).
(D) A step of expanding the pore diameter after the step (c).
(E) A step of alternately repeating the step (c) and the step (d).

In the step (a), it is preferable to anodize at a voltage of 90 V or higher.
In the step (a), it is preferable that the anodization is started at a voltage of less than 90V, the voltage is increased stepwise or continuously, and finally anodization is performed at a voltage of 90V or more.

The method for producing an article having a fine concavo-convex structure on the surface thereof according to the present invention includes a fine concavo-convex structure comprising a plurality of pores formed on the surface of the mold obtained by the mold production method of the present invention. It is characterized by being transferred to.
The mold of the present invention has an aluminum substrate and an oxide film having a plurality of pores formed on the surface of the aluminum substrate, and the average interval between the plurality of pores is 180 nm or more, The unevenness of the depth of the plurality of pores is 50 nm or less.

According to the mold manufacturing method of the present invention, an oxide film with little pore depth unevenness can be formed even if the pore spacing is 180 nm or more.
According to the method for producing an article having a fine concavo-convex structure on the surface according to the present invention, an article with little height unevenness of the convex portions can be obtained even if the interval between the convex portions is 180 nm or more.

It is sectional drawing which shows the manufacturing process of the mold in which the oxide film which has several pores was formed in the surface of an aluminum base material. It is sectional drawing which shows an example of the cell used for the back surface cooling of an aluminum base material. 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. It is sectional drawing which shows an example of the article | item which has a fine concavo-convex structure on the surface. It is a figure which shows the reflectance of the articles | goods which have the fine concavo-convex structure of Example 2 on the surface. It is a figure which shows the reflectance of the articles | goods which have the fine concavo-convex structure of the comparative example 2 on the surface.

In the present specification, the “pore” means a concave portion having a fine concavo-convex structure formed on an oxide film on the surface of an aluminum substrate.
Moreover, the “interval between pores” means a center-to-center distance between adjacent pores.
In addition, “there is little variation in the size of the pore generation point” means that when the mold surface is observed with an electron microscope, the distance between the centers of the adjacent pores selected at random and the average interval between the pores are This means that the difference is within 30 nm.
Further, the “fine concavo-convex structure” means a structure in which the average interval between the convex portions or the concave portions is nanoscale.
“(Meth) acrylate” means acrylate or methacrylate.
“Active energy rays” mean visible light, ultraviolet rays, electron beams, plasma, heat rays (infrared rays, etc.) and the like.

<Mold manufacturing method>
The method for producing a mold of the present invention is a method having steps (a) to (e).
(A) A step of anodizing the surface of the aluminum substrate to form an oxide film.
(B) A step of removing the oxide film formed in the step (a).
(C) After the step (b), the surface of the aluminum base is anodized at a voltage less than 90% of the maximum voltage applied in the step (a) to form an oxide film having a plurality of pores. Process.
(D) A step of expanding the pore diameter after the step (c).
(E) A step of alternately repeating the step (c) and the step (d).

(Process (a))
In step (a), as shown in FIG. 1, the surface of the aluminum substrate 10 is anodized in an electrolytic solution to form an oxide film 14 (anodized porous alumina) having a plurality of pores 12. This is an oxide film forming step.
By immersing a part or all of the surface of the aluminum substrate 10 in the electrolytic solution and anodizing, the oxide film 14 can be formed on the portion immersed in the electrolytic solution. The oxide film 14 formed at the initial stage of anodization has non-uniform positions and sizes of the pores 12 and no regularity. However, the oxide film 14 becomes thick by continuing the anodization at a constant voltage. At the same time, the regularity of the arrangement of the pores 12 gradually increases.

The shape of the aluminum substrate 10 is not particularly limited, and may be any shape as long as it can be used as a mold, such as a plate shape, a columnar shape, or a cylindrical shape.
The purity of the aluminum substrate 10 is preferably more than 99.0% by mass, more preferably 99.5% by mass or more, and further preferably 99.9% by mass or more. If the purity of the aluminum substrate 10 is more than 99.0% by mass, the macro unevenness generated by the removal of the impurity intermetallic compound in the mold manufacturing process does not increase too much.
The aluminum substrate 10 is preferably one whose surface is polished by a known polishing method (mechanical polishing, feather polishing, chemical polishing, electrolytic polishing, etc.) and at least a part to be anodized is mirror-finished.

  Examples of the electrolytic solution include an acidic aqueous solution or an alkaline aqueous solution, and an acidic aqueous solution is preferable. Examples of the acidic aqueous solution include inorganic acids (sulfuric acid, phosphoric acid, etc.), organic acids (oxalic acid, malonic acid, tartaric acid, succinic acid, malic acid, citric acid, etc.), and sulfuric acid, oxalic acid, and phosphoric acid are particularly preferable. . These acids may be used individually by 1 type, and may be used in combination of 2 or more type.

  The preferable range of the concentration of the electrolytic solution varies depending on the type of acid. For example, in the case of oxalic acid, the concentration of the electrolytic solution is preferably 0.05 to 2.0M. In the case of phosphoric acid, the concentration of the electrolytic solution is preferably 0.1 to 5.0M. When the concentration of the electrolytic solution is higher, the regularity of the arrangement of the pores 12 tends to be improved, and pores having a uniform depth are easily obtained after the steps (b) to (e) described later. . When the concentration of the electrolytic solution is lower than the above range, the size of the recess 16 generated when the oxide film formed in the step (a) is removed in the step (b) varies, and is formed after the step (c). This is a cause of unevenness in the depth of the pores 12. When the concentration of the electrolytic solution is higher than the above range, the formation speed of the oxide film 14 is remarkably increased, and it becomes difficult to suppress the thickness of the oxide film 14 to less than 15 μm described later.

  10-50 degreeC is preferable, as for the temperature of electrolyte solution, 10-40 degreeC is more preferable, and 10-35 degreeC is further more preferable. When the temperature of the electrolytic solution is within the above range, a phenomenon called “burning” in which a very high current density flows and the pores 12 are broken hardly occurs. In addition, since the variation in the size of the recess 16 generated when the oxide film is removed in the step (b) is reduced, unevenness in the depth of the pores 12 is suppressed, and an oxide film suitable as a mold can be easily formed. Moreover, when the variation in the size of the recess 16 is reduced, the regularly arranged pores 12 are easily formed.

  The voltage in the anodic oxidation in the step (a) is preferably 90 V or more, more preferably 95 V or more, and further preferably 100 V or more. The average interval between the pores 12 of the oxide film 14 increases depending on the voltage. When anodization is performed at a voltage of 90 V or more, the average interval between the pores 12 is 180 nm or more, and the pore diameter becomes large. Therefore, it is easy to release during transfer and is suitable for long-term use as a mold.

As a method of anodizing, a method of applying a maximum voltage of 90 V or higher from the beginning may be used. After anodizing is started with an initial voltage of less than 90 V, the voltage is increased stepwise or continuously, and finally Alternatively, a method of anodizing at a maximum voltage of 90 V or more may be used. The latter method is effective because it can be suppressed by gradually increasing from an initial voltage of less than 90 V, even under conditions where an initial voltage of 90 V or more is applied. preferable. Here, the “initial voltage” refers to the voltage at the start in step (a). The “maximum voltage” refers to the maximum value of the voltage in the step (a) and coincides with the voltage at the end of the step (a). The pores 12 of the oxide film 14 are arranged at an average interval corresponding to the highest voltage.
The anodic oxidation time at the maximum voltage is preferably 2 minutes or longer, more preferably 3 minutes or longer, and even more preferably 5 minutes or longer. When the anodic oxidation time at the maximum voltage is less than 2 minutes, there is a possibility that the average interval of the pores 12 corresponding to the maximum voltage does not appear.

In the step (a), as a specific example of a method of stepwise increasing from an initial voltage of less than 90V to a maximum voltage of 90V or more, anodization is performed for 5 minutes with the initial voltage set to 60V, and then increased to 70V. Then, anodization is performed for 5 minutes, and the voltage is further raised to 80 V, anodization is performed for 5 minutes, and finally the voltage is raised to 90 V and anodization is performed for 10 minutes.
The rising speed when raising the voltage is preferably 0.05 to 5 V / s. If the rising speed is less than 0.05 V / s, an excessive oxide film 14 is formed thick while the voltage is increased, and it is difficult to suppress the thickness of the oxide film 14 at the end to less than 15 μm described later. It becomes. If the rising speed exceeds 5 V / s, the current density that flows increases momentarily, which may cause burns.

In the step (a), an anodization may be performed while flowing a refrigerant on the back surface of the aluminum substrate 10 and indirectly cooling the surface (hereinafter also referred to as back surface cooling). Here, the “back surface” refers to a portion corresponding to the back side of the surface in contact with the electrolytic solution (a part or all of the surface of the aluminum substrate 10). As a method for performing the back surface cooling, for example, in the back surface cooling of the plate-shaped aluminum base material 10, as shown in FIG. 2, an opening 52 for bringing the coolant into contact with the back surface of the aluminum base material 10 is formed. For example, a method in which the aluminum base material 10 is fixed and anodized so that the back surface side of the aluminum base material 10 is in contact with the dedicated cell 50 in which the refrigerant flow path 54 is formed.
When anodizing is performed at a high voltage of 90 V or higher, there is a case in which a phenomenon called “thermal runaway” in which the temperature of the electrolytic solution continues to rise due to the influence of reaction heat may be accompanied. In such a case, thermal runaway can be suppressed by cooling the surface by performing backside cooling.

As a refrigerant used for backside cooling, deionized water is preferable from the viewpoint of simplicity and safety.
The difference between the temperature of the refrigerant and the temperature of the electrolytic solution is preferably less than 5 ° C, more preferably 2 ° C or less, and even more preferably 1 ° C or less. If the temperature of the refrigerant used for backside cooling differs by 5 ° C. or more from the temperature of the electrolytic solution, the reaction temperature may deviate from the temperature of the electrolytic solution due to the effect of backside cooling.
The flow rate of the refrigerant is preferably 0.1 m / s or more, more preferably 0.15 m / s or more, and further preferably 0.2 m / s or more. If the flow rate of the refrigerant is less than 0.1 m / s, there is a possibility that thermal runaway cannot be suppressed.

The thickness of the oxide film 14 formed by the step (a) is preferably less than 15 μm, and more preferably 10 μm or less. When the oxide film 14 thicker than the above-described range is formed, the level difference of the crystal grain boundary of the aluminum base 10 becomes so large that it can be visually recognized when the oxide film 14 is removed. When such a mold is used, the step of the crystal grain boundary is also transferred, which may cause the appearance of the resulting article to be defective.
The thickness of the oxide film is adjusted by appropriately setting conditions such as the concentration of the electrolytic solution and the anodic oxidation time.

(Process (b))
Step (b) is an oxide film removal step for removing the oxide film 14 formed in step (a) as shown in FIG.
By removing the oxide film 14, a recess 16 formed corresponding to the shape of the bottom (barrier layer) of the oxide film 14 is generated. When the oxide film 14 in which the pores 12 formed in the step (a) are regularly arranged is removed, there is little variation in size, and the regularly arranged depressions 16 are formed.

  Examples of the method for removing the oxide film 14 include a method of immersing in a solution that selectively dissolves alumina without dissolving aluminum. Examples of such a solution include a chromic acid / phosphoric acid mixed solution.

  Further, when high regularity is required for the pores, it is preferable to remove all of the oxide film formed in step (a) in step (b), but the present invention is not limited to this, In (b), not all of the oxide film 14 formed in the step (a) may be removed, and at least a part thereof may be removed. When part of the oxide film is removed in step (b), the oxide film is removed so that it is 90% or more of the oxide film formed in step (a) and the thickness of the oxide film is 100 nm or less. It is preferable.

(Process (c))
In the step (c), as shown in FIG. 1, after the step (b), the aluminum substrate 10 is anodized again in the electrolytic solution at a voltage less than 90% of the maximum voltage applied in the step (a). This is a second oxide film forming step in which the oxide film 14 having the plurality of pores 12 is formed again.
When the anodic oxidation is performed again in a state where the dent 16 is formed on the surface of the aluminum substrate 10, the dent 16 acts as a pore generation point, and the new pore 12 of the oxide film 14 is generated at a position corresponding to the dent 16. . When the variation in the size of the recess 16 is small, unevenness in the depth of the pores 12 is suppressed, and an oxide film suitable as a mold can be formed. Moreover, when the variation in the size of the recess 16 is reduced, the regularly arranged pores 12 are easily formed.

  The preferable range of the concentration of the electrolytic solution varies depending on the type of acid. For example, in the case of oxalic acid, the concentration of the electrolytic solution is preferably 0.05 to 0.3M. In the case of phosphoric acid, the concentration of the electrolytic solution is preferably 0.1 to 1.0M. If the concentration of the electrolytic solution is lower than the above range, the concentration is too low to act as an acidic electrolytic solution, and a flat oxide film may be formed instead of the porous oxide film 14. A flat oxide film cannot serve as a mold for transferring a fine relief structure. If the concentration of the electrolytic solution is higher than the above range, the formation rate of the oxide film 14 is increased, and it becomes difficult to adjust the depth of the pores 12.

  10-25 degreeC is preferable and the temperature of electrolyte solution has more preferable 10-17 degreeC. When the temperature of the electrolytic solution is within the above range, it is easy to adjust the depth of the pores, and pores with little depth unevenness can be formed.

  The voltage in the anodic oxidation in the step (c) is less than 90% of the maximum voltage applied in the step (a), preferably 87% or less, more preferably 83% or less. When anodization is performed at a voltage of 90% or more of the maximum voltage applied in the step (a), the unevenness of the depth of the formed pores 12 becomes remarkable. When such a mold is used, depending on the measurement location, There may be a difference in performance. Although the unevenness of the depth of the pores 12 has never been small, specifically, it is preferably 50 nm or less, more preferably less than 50 nm, further preferably 30 nm or less, and particularly preferably 25 nm or less.

The anodizing time is preferably 3 to 60 seconds. If the anodic oxidation time is less than 3 seconds, the thickness of the finally obtained oxide film 14 may be less than 0.01 μm described later. In such an oxide film 14, the depth of the pores 12 is less than 0.01 μm, and when used as a mold, the resulting article may not exhibit sufficient antireflection performance. If the anodic oxidation time exceeds 60 seconds, the thickness of the finally obtained oxide film 14 may exceed 0.8 μm described later. In such a case, since the pores 12 become deeper as the oxide film 14 becomes thicker, when used as a mold, there is a risk that a mold release failure is likely to occur.
Also in step (c), the temperature of the aluminum substrate 10 may be controlled as in step (a).

(Process (d))
Step (d) is a hole diameter enlargement process step in which part of the oxide film 14 formed in step (c) is removed to enlarge the hole diameter of the pores 12, as shown in FIG.

  As a specific method of the pore diameter expansion treatment, there is a method of immersing in a solution dissolving alumina and expanding the diameter of the pores 12 formed in the oxide film 14 by etching. Examples of such a solution include a phosphoric acid aqueous solution of about 5.0% by mass. The longer the immersion time, the larger the diameter of the pores 12.

(Process (e))
As shown in FIG. 1, the step (e) is a repeating step of adjusting the depth and shape of the pores by alternately repeating the step (c) and the step (d).
When the pore diameter of the pores 12 is enlarged and then anodized again, pores 12 having a small pore diameter that extend downward from the bottom of the pores 12 with the enlarged pore diameter are further formed. Further, by alternately repeating the step (c) and the step (d), the shape of the pores 12 can be tapered so that the diameter gradually decreases in the depth direction from the opening, as shown in FIG. As a result, it is possible to obtain a mold 18 having an oxide film formed of a plurality of periodic pores 12 formed on the surface. In addition, the pores 12 having various shapes are formed by appropriately setting the conditions of the step (c) and the step (d), for example, the time of the pore size enlargement process, and the temperature and concentration of the solution used for the pore size enlargement treatment. The oxide film 14 can be formed. What is necessary is just to set these conditions suitably according to the use etc. of the articles | goods produced from a mold.

The number of times of the step (c) is preferably at least 3 times including the step (c) performed before the step (e) from the viewpoint that the smoother taper shape can be obtained as the number of times increases. Similarly, the number of times of the step (d) is preferably at least three times including the step (d) performed before the step (e) because the smoother taper shape can be obtained as the number of times increases. If the number of each is less than 2 times, the pore diameter tends to decrease discontinuously, and when an antireflection article (such as an antireflection film) is manufactured from such a mold, the reflectance reduction effect may be inferior. There is sex.
Step (e) may be completed in step (c) or may be completed in step (d).

  Deeper pores 12 can be obtained as the anodic oxidation in the step (c) is performed for a longer time, but when used as a mold for transferring the fine concavo-convex structure, the oxide film 14 finally obtained through the step (e) The thickness may be about 0.01 to 0.8 μm. The anodic oxidation conditions (type of electrolyte, concentration, temperature, etc.) other than the voltage in the step (c) are not necessarily matched with those in the step (a), and the thickness of the oxide film 14 is easily changed to a condition that can be easily adjusted. May be.

(mold)
According to the manufacturing method of the present invention, tapered pores 12 whose diameter gradually decreases in the depth direction from the opening on the surface of the aluminum base material 10 are less uneven in depth and regularly arranged. As a result, a mold having an oxide film (anodized porous alumina) having a fine concavo-convex structure formed on the surface can be manufactured. Moreover, according to the manufacturing method of the present invention, a mold having an oxide film with little unevenness in the depth of the pores can be manufactured even if the average interval between the pores is 180 nm or more. Specifically, a mold having a pore depth unevenness of 50 nm or less can be produced. The depth unevenness of the pores is preferably less than 50 nm, more preferably 30 nm or less, and further preferably 25 nm or less.

The pore depth unevenness is measured as follows.
First, a part of the mold is cut out, and platinum is vapor-deposited on the longitudinal section for 1 minute, and observed using a field emission scanning electron microscope. A cross-sectional sample is observed at two locations at a magnification of 50,000 times, and the depths of 10 pores in each observation range are averaged to determine the depth of the pores at each observation point. By comparing the depth of the pores at each observation point, the depth unevenness of the pores in the same sample is obtained.

The average interval between adjacent pores in the mold is preferably 180 nm or more and 600 nm or less (that is, the wavelength of visible light or less).
When the mold is used for the production of an antireflection article (antireflection film, etc.), the average interval between the pores is 600 nm or less, and the depth of the pores is preferably 100 nm or more, more preferably 150 nm or more. preferable. When a mold having a pore depth of less than 100 nm is used, the antireflection performance of the antireflection article may be insufficient. The aspect ratio (= depth / average interval) of the pores of the mold is preferably 0.5 or more, and more preferably 1 or more. If the aspect ratio is 0.5 or more, a surface with low reflectance can be formed, and the incident angle dependency thereof is sufficiently small.

  The surface on which the fine uneven structure of the mold 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 polymer or a fluorine polymer, a method of depositing a fluorine compound, a method of coating a fluorine surface treatment agent or a fluorine silicone surface treatment agent, and the like.

(Function and effect)
In the mold manufacturing method of the present invention described above, after removing the oxide film formed first, the generated depression is used as a pore generation point, and the maximum voltage applied by the first anodic oxidation is 90%. Since the oxide film having a plurality of pores is formed by anodizing again at a voltage of less than 10%, the oxide film has little pore depth unevenness even when the pore spacing is 180 nm or more. Can be formed.
In the mold of the present invention, since the unevenness of the depth of the plurality of pores is 50 nm or less, there is little unevenness in the height of the convex portion when the mold surface structure is transferred to the surface of the article body. An article is obtained.

<Production method>
The method for producing an article having a fine concavo-convex structure on the surface thereof according to the present invention includes a fine concavo-convex structure comprising a plurality of pores formed on the surface of the mold obtained by the mold production method of the present invention. It is the method of transferring to.
In an article manufactured by transferring the fine concavo-convex structure (pores) of the mold, the reverse structure (convex part) of the fine concavo-convex structure of the mold is transferred on the surface in a relationship between the key and the keyhole.

  As a method for transferring the fine concavo-convex structure of the mold to the surface of the article main body, for example, an uncured active energy ray-curable resin composition is filled between the mold and the transparent substrate (article main body), In a state where the active energy ray-curable resin composition is in contact with the structure, a method of releasing the mold after irradiating the active energy ray to cure the active energy ray-curable resin composition is preferable. Thereby, an article in which a fine uneven structure made of a cured product of the active energy ray-curable resin composition is formed on the surface of the transparent substrate can be produced. The fine uneven structure of the obtained article is an inverted structure of the fine uneven structure of the mold.

(Article body)
As a transparent base material, since active energy ray irradiation is performed through the transparent base material, a material that does not significantly inhibit irradiation of active energy rays is preferable. Examples of the material for the transparent substrate include polyester resin (polyethylene terephthalate, polybutylene terephthalate, etc.), polymethacrylate resin, polycarbonate resin, vinyl chloride resin, ABS resin, styrene resin, glass and the like.

(Active energy ray-curable resin composition)
Since the method using the active energy ray-curable resin composition does not require heating or cooling after curing as compared with the method using the thermosetting resin composition, the fine uneven structure can be transferred in a short time, Suitable for mass production.
As a method of filling the active energy ray curable resin composition, a method of supplying the active energy ray curable resin composition between the mold and the transparent substrate and then rolling and filling the active energy ray curable resin composition, Examples thereof include a method of laminating a transparent substrate on the applied mold, a method of previously applying an active energy ray-curable resin composition on a transparent substrate, and laminating the mold on the mold.

  The active energy ray-curable resin composition contains a polymerization reactive compound and an active energy ray polymerization initiator. In addition to the above, a non-reactive polymer or active energy ray sol-gel reactive component may be contained depending on the application, and a thickener, leveling agent, ultraviolet absorber, light stabilizer, heat stabilizer, solvent Various additives such as inorganic fillers may be included.

Examples of the polymerization reactive compound include monomers, oligomers, and reactive polymers having a radical polymerizable bond and / or a cationic polymerizable bond in the molecule.
Examples of the monomer having a radical polymerizable bond include a monofunctional monomer and a polyfunctional monomer.

  Monofunctional monomers having a radical polymerizable bond include (meth) acrylate derivatives (methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) Acrylate, s-butyl (meth) acrylate, t-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, 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.). These may be used alone or in combination of two or more.

  As the polyfunctional monomer having a radical polymerizable bond, bifunctional monomers (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) acryloxyethoxy) Nyl) propane, 2,2-bis (4- (3- (meth) 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 of bisphenol A di (meth) acrylate, propylene oxide adduct of bisphenol A Di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, divinylbenzene, methylenebisacrylamide, etc.), trifunctional monomers (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, etc.), tetrafunctional or higher monomer ( Condensation reaction mixture of succinic acid / trimethylolethane / acrylic acid, dipentaerystol hexa (meth) acrylate, dipentaerystol penta (meth) acrylate, ditrimethylolpropane tetraacrylate, tetramethylolmethane tetra (meth) acrylate, etc.) , Bifunctional or higher urethane acrylate, bifunctional or higher polyester acrylate, and the like. These may be used alone or in combination of two or more.

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, and a monomer having an epoxy group is particularly preferable.
Examples of the oligomer or reactive polymer having a radical polymerizable bond and / or a cationic polymerizable bond in the molecule include unsaturated polyesters such as a condensate of unsaturated dicarboxylic acid and polyhydric alcohol; polyester (meth) acrylate, poly Ether (meth) acrylate, polyol (meth) acrylate, 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, etc. Can be mentioned.

  As the active energy ray polymerization initiator, a known polymerization initiator can be used, and it is preferable to select appropriately according to the type of active energy ray used when the active energy ray curable resin composition is cured.

  When using a photocuring reaction, photopolymerization initiators include 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. These may be used alone or in combination of two or more.

  When an electron beam curing reaction is used, polymerization initiators include benzophenone, 4,4-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophenone, methyl orthobenzoyl benzoate, 4-phenylbenzophenone, and t-butylanthraquinone. 2-ethylanthraquinone, thioxanthone (2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, etc.), acetophenone (diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, Benzyldimethyl ketal, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4 Morpholinophenyl) -butanone), 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-bisacridinylheptane, 9 -Phenylacridine and the like. These may be used alone or in combination of two or more.

  The content of the active energy ray polymerization initiator in the active energy ray curable resin composition is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the polymerizable compound. When the active energy ray polymerization initiator is less than 0.1 part by mass, the polymerization is difficult to proceed. When the active energy ray polymerization initiator exceeds 10 parts by mass, the cured resin may be colored or the mechanical strength may be lowered.

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 component include alkoxysilane compounds and alkyl silicate 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.

(Manufacturing equipment)
An article having a fine concavo-convex structure on its surface is manufactured as follows using, for example, a manufacturing apparatus shown in FIG.
Active energy ray curable from the tank 22 between the roll-shaped mold 20 having a fine concavo-convex structure (not shown) on the surface and a strip-shaped film 42 (transparent substrate) moving along the surface of the roll-shaped mold 20. The resin composition 38 is supplied.

  The film 42 and the active energy ray curable resin composition 38 are nipped between the roll-shaped mold 20 and the nip roll 26 whose nip pressure is adjusted by the pneumatic cylinder 24, and the active energy ray curable resin composition 38 is The film 42 and the roll-shaped mold 20 are uniformly distributed, and at the same time, the concave portions of the fine concavo-convex structure of the roll-shaped mold 20 are filled.

The active energy ray curable resin composition 38 is irradiated through the film 42 from the active energy ray irradiation device 28 installed below the roll-shaped mold 20 to cure the active energy ray curable resin composition 38. Thus, the cured resin layer 44 to which the fine uneven structure on the surface of the roll-shaped mold 20 is transferred is formed.
By peeling the film 42 having the cured resin layer 44 formed on the surface from the roll-shaped mold 20 with the peeling roll 30, an article 40 as shown in FIG. 4 is obtained.

Examples of the active energy ray irradiation device 28 include a high-pressure mercury lamp and a metal halide lamp.
The irradiation amount of an active energy ray should just be the energy amount which hardening of an active energy ray curable resin composition advances, and is about 100-10000mJ / cm < ² > normally.

(Goods)
The article 40 shown in FIG. 4 has a cured resin layer 44 formed on the surface of a film 42 (transparent substrate).
The cured resin layer 44 is a film made of a cured product of the active energy ray curable resin composition, and has a fine uneven structure on the surface.
The fine concavo-convex structure on the surface of the article 40 in the case of using the mold in the present invention is formed by transferring the fine concavo-convex structure on the surface of the oxide film. A plurality of convex portions 46.

  As the fine concavo-convex structure, a so-called moth-eye structure in which a plurality of protrusions (convex portions) having a substantially conical shape or a pyramid shape are arranged is preferable. It is known that the moth-eye structure in which the distance between the protrusions is less than or equal to the wavelength of visible light is an effective anti-reflection measure by continuously increasing the refractive index from the refractive index of air to the refractive index of the material. It has been.

The article manufactured by the manufacturing method of the present invention exhibits various performances such as antireflection performance and water repellency performance by the fine uneven structure on the surface.
When an article having a fine concavo-convex structure is a sheet or film, the surface of an object such as an image display device (TV, mobile phone display, etc.), display panel, meter panel, etc. is used as an antireflection film. It can be used by pasting it on or insert molding it. In addition, taking advantage of water repellency, it is also used as a member for objects that may be exposed to rain, water, steam, etc., such as bathroom windows and mirrors, solar cell members, automobile mirrors, signboards, glasses lenses, etc. be able to.
When an article having a fine concavo-convex structure on its surface is a three-dimensional shape, an antireflection article is manufactured using a transparent substrate having a shape suitable for the application, and this is used as a member constituting the surface of the object. You can also.

When the object is an image display device, not only the surface thereof, but also an article having a fine uneven structure on the surface may be attached to the front plate, or the front plate itself may be It can also consist of an article having a structure on its surface. For example, an article having a fine concavo-convex structure on the surface of a rod lens array attached to a sensor array for reading an image, a cover glass of an image sensor such as a FAX, a copying machine or a scanner, or a contact glass for placing an original of a copying machine May be used. Further, by using an article having a fine concavo-convex structure on the surface of a light receiving portion of an optical communication device such as visible light communication, signal reception sensitivity can be improved.
In addition to the uses described above, articles having a fine concavo-convex structure on the surface can be developed for optical uses such as optical waveguides, relief holograms, optical lenses, and polarization separation elements, and for use as cell culture sheets.

(Function and effect)
In the method for manufacturing an article having a fine concavo-convex structure on the surface according to the present invention described above, since the mold obtained by the mold manufacturing method of the present invention is used, the interval between the convex portions is 180 nm or more. Even so, an article with less unevenness in the height of the projections can be obtained. Moreover, by using the mold obtained by the method for producing a mold of the present invention, an article having a surface having an inverted structure of the fine concavo-convex structure of the mold can be easily produced in one step.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
Various measurements were performed by the following methods.

(Measurement of mold pores)
A part of the mold having an oxide film formed on the surface is cut out, platinum is deposited on the surface for 1 minute, and an acceleration voltage of 3.00 kV is used using a field emission scanning electron microscope (JSM-7400F, manufactured by JEOL Ltd.). And magnified 10,000 times. The average interval (pitch) of the pores was obtained by averaging the distance between the centers of the six pores arranged in a straight line. Similarly, the observations were magnified at three different points and the average distance between the centers of the pores calculated from each was averaged to determine the average interval between the pores. In addition, the center-to-center distance of 10 pairs of adjacent pores selected at random was calculated, and the degree of variation in the size of the pore generation point was judged by comparison with the average interval of the pores. That is, when the difference between the distance between the centers of adjacent pores and the average interval between the pores is taken, the smaller the variation in the difference of 10 pairs measured in the same way, the smaller the variation in the size of the pore generation point. It means that the holes are regularly arranged.
Further, a part of the mold was cut out, and platinum was vapor-deposited on the longitudinal section for 1 minute, and observed at an acceleration voltage of 3.00 kV using the same field emission scanning electron microscope. The cross-sectional sample was observed at two locations at a magnification of 50,000, and the depths of 10 pores in each observation range were averaged to determine the pore depth for each observation point. By comparing the depth of the pores at each observation point, the depth unevenness of the pores in the same sample was investigated.

(Reflectance measurement)
A film was prepared by transferring the fine concavo-convex structure on the surface of the mold, and the back surface (side on which the fine concavo-convex structure was not formed) was applied with a black spray to prepare a sample. Using a spectrophotometer (manufactured by Hitachi, Ltd., U-4000), light is applied to the surface of the sample (the surface on which the fine concavo-convex structure is formed) at an incident angle of 5 °, and regular reflection in the wavelength range of 380 nm to 780 nm. The rate was measured. With respect to one sample, the reflectance was measured under the same conditions at three points separated from each other by 1 cm or more.

(Measurement of fine uneven structure of articles)
Platinum was vapor-deposited for 10 minutes on the surface and longitudinal section of the film to which the fine concavo-convex structure of the mold was transferred, and using a field emission scanning electron microscope (JSM-7400F, manufactured by JEOL Ltd.) under the condition of an acceleration voltage of 3.00 kV. The surface and cross section of the article were observed.
The surface of the article was magnified 10,000 times and observed, and the average distance (pitch) between the protrusions was obtained by averaging the distances between the centers of the six protrusions arranged in a straight line. Further, the cross section of the article was observed at a magnification of 50,000 times, and the height of the ten protrusions was averaged to obtain the protrusion height.

[Example 1]
An aluminum plate having a purity of 99.99% by mass and a thickness of 0.3 mm was cut into a size of 30 mm × 90 mm, and electropolished in a perchloric acid / ethanol mixture (volume ratio = 1/4), and this was subjected to aluminum polishing. Used as material.

(Process (a))
The aluminum substrate was fixed so that the back side of the aluminum substrate was in contact with the cell shown in FIG. 2, and the temperature was adjusted to 32 ° C. while circulating 31 ° C. cooling water at a flow rate of 0.2 m / s. The surface (20 mm × 50 mm) of the aluminum substrate in contact with the 5M oxalic acid aqueous solution was anodized. By anodizing at an initial voltage of 60 V for 10 minutes, followed by anodizing at 70 V for 10 minutes, anodizing at 80 V for 5 minutes, anodizing at 90 V for 5 minutes, and finally anodizing at 100 V for 5 minutes. An oxide film having

(Process (b))
The aluminum substrate on which the oxide film was formed was immersed in a 70 ° C. aqueous solution in which 6% by mass of phosphoric acid, 1.8% by mass and chromic acid were mixed for 6 hours to dissolve and remove the oxide film. A dimple was formed as a pore generation point for oxidation.

(Process (c))
The aluminum base material having a pore generation point was immersed in a 0.05 M aqueous solution of oxalic acid adjusted to 17 ° C. and anodized at 80 V for 6 seconds to form an oxide film on the surface of the aluminum base material again.

(Process (d))
The aluminum base material on which the oxide film was formed was immersed in a 5% by mass phosphoric acid aqueous solution adjusted to 30 ° C. for 20 minutes, and subjected to a pore diameter enlargement process for expanding the pores of the oxide film.

(Process (e))
The step (c) and the step (d) were repeated alternately 5 times. That is, the process (c) and the process (d) were performed 6 times each. After the obtained mold was washed with deionized water, the surface moisture was removed by air blow. Table 1 shows the type and concentration of the electrolytic solution, the anodic oxidation voltage, the average interval and depth of the pores, and the unevenness of the depth.

[Example 2]
The oxidation time at 100V in step (a) is 15 minutes, the temperature of the electrolytic solution in step (c) is 16 ° C., the anodic oxidation condition is 20 seconds at 80V, and the temperature of the phosphoric acid aqueous solution in step (d) is 32. A mold was manufactured in the same manner as in Example 1 except that the temperature was set to 18 ° C. and the immersion time was 18 minutes, and the number of times of the step (c) and the step (d) was 5 in total. Table 1 shows the type and concentration of the electrolytic solution, the anodic oxidation voltage, the average interval and depth of the pores, and the unevenness of the depth.

The mold thus obtained was immersed in a solution obtained by diluting OPTOOL DSX (manufactured by Daikin Chemicals Sales Co., Ltd.) to 0.1% by mass with Durasurf HD-ZV (manufactured by Daikin Chemicals Sales Co., Ltd.) for 10 minutes. The mold was released by air drying overnight.
An active energy ray-curable resin composition having the following composition is filled between the mold subjected to the mold release treatment and the acrylic film (manufactured by Mitsubishi Rayon, Acryprene HBS010) as a transparent substrate, and integrated light quantity is obtained with a high-pressure mercury lamp. The active energy ray-curable resin composition was cured by irradiating with 1000 mJ / cm ² of ultraviolet rays. Thereafter, the mold was peeled off to obtain a film composed of a transparent substrate and a cured product of the cured composition.
A fine concavo-convex structure was formed on the surface of the film thus produced, the height of the protrusions was 430 to 450 nm, and the average interval (pitch) of the protrusions was 200 nm. Moreover, the reflectance of the produced film was measured. The results are shown in FIG.

(Active energy ray-curable resin composition)
Trimethylolethane / acrylic acid / succinic anhydride condensation ester: 45 parts by mass,
1,6-hexanediol diacrylate: 45 parts by mass,
X-22-21602 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd .: 10 parts by mass,
BASF Irgacure 184 (trade name): 2.7 parts by mass,
BASF Irgacure 819 (trade name): 0.18 parts by mass.

Example 3
The time of anodic oxidation at 100V in step (a) is 15 minutes, the temperature of the electrolyte in step (c) is 16 ° C., the anodic oxidation condition is 15 seconds at 85V, and the temperature of the phosphoric acid aqueous solution in step (d) Was 32 ° C., the immersion time was 19 minutes, and the mold was produced in the same manner as in Example 1 except that the number of times of step (c) and step (d) was 5 in total. Table 1 shows the type and concentration of the electrolytic solution, the anodic oxidation voltage, the average interval and depth of the pores, and the unevenness of the depth.

Example 4
In step (a), anodizing at an initial voltage of 60V for 10 minutes, followed by anodizing at 70V for 10 minutes, anodizing at 80V for 5 minutes, and finally anodizing at 90V for 15 minutes, the anode in step (c) The oxidation condition was 20 seconds at 80 V, the temperature of the phosphoric acid aqueous solution in step (d) was 32 ° C., the immersion time was 19 minutes, and the number of times of step (c) and step (d) was 5 times in total. Except for the above, a mold was produced in the same manner as in Example 1. Table 1 shows the type and concentration of the electrolytic solution, the anodic oxidation voltage, the average interval and depth of the pores, and the unevenness of the depth.

Example 5
Using the same aluminum base material as in Example 1, steps (a) to (e) were performed as follows to produce a mold.
(Process (a))
The aluminum substrate was immersed in a 0.2 M aqueous phosphoric acid solution adjusted to 16 ° C., and both surfaces of the immersed portion (30 mm × 60 mm) were anodized. An oxide film having pores was formed by anodizing at a constant voltage of 150 V for 30 minutes.
(Process (b))
The aluminum substrate on which the oxide film was formed was immersed in a 70 ° C. aqueous solution in which 6% by mass of phosphoric acid, 1.8% by mass and chromic acid were mixed for 6 hours to dissolve and remove the oxide film. A dimple was formed as a pore generation point for oxidation.
(Process (c))
The aluminum base material having a pore generation point was immersed in a 0.2 M phosphoric acid aqueous solution adjusted to 16 ° C., and anodized at 130 V for 40 seconds to form an oxide film on the surface of the aluminum base material again.
(Process (d))
The aluminum base material on which the oxide film was formed was immersed in a 5% by mass phosphoric acid aqueous solution adjusted to 32 ° C. for 20 minutes, and subjected to a pore diameter enlargement process for expanding the pores of the oxide film.
(Process (e))
The step (c) and the step (d) were further alternately repeated 4 times. That is, the step (c) and the step (d) were performed 5 times each. After the obtained mold was washed with deionized water, the surface moisture was removed by air blow. Table 1 shows the type and concentration of the electrolytic solution, the anodic oxidation voltage, the average interval and depth of the pores, and the unevenness of the depth.

[Comparative Example 1]
A mold was manufactured in the same manner as in Example 2 except that the anodic oxidation conditions in step (c) were set at 90 V for 10 seconds. Table 1 shows the type and concentration of the electrolytic solution, the anodic oxidation voltage, the average interval and depth of the pores, and the unevenness of the depth.

[Comparative Example 2]
The same as in Example 3 except that the concentration of the electrolytic solution in step (c) was 0.025M, the anodic oxidation condition was 100 V for 6 seconds, and the immersion time in the phosphoric acid aqueous solution in step (d) was 25 minutes. The mold was manufactured by the method. Table 1 shows the type and concentration of the electrolytic solution, the anodic oxidation voltage, the average interval and depth of the pores, and the unevenness of the depth.
The mold thus obtained was subjected to release treatment in the same manner as in Example 2, and a film was produced in the same manner. A fine uneven structure was formed on the surface of the produced film, the height of the protrusions was 410 to 470 nm, and the distance (pitch) between the protrusions was 200 nm. Moreover, the reflectance of the manufactured film was measured similarly to Example 2. The results are shown in FIG.

[Comparative Example 3]
Comparative Example 1 except that in step (a), anodization was performed at an initial voltage of 60 V for 10 minutes, followed by anodization at 70 V for 10 minutes, anodization at 80 V for 5 minutes, and finally anodization at 90 V for 15 minutes. A mold was manufactured in the same manner. Table 1 shows the type and concentration of the electrolytic solution, the anodic oxidation voltage, the average interval and depth of the pores, and the unevenness of the depth.

[Comparative Example 4]
A mold was manufactured in the same manner as in Example 5 except that the anodic oxidation conditions in step (c) were set to 150 V for 40 seconds. Table 1 shows the type and concentration of the electrolytic solution, the anodizing voltage, the average interval and depth of the pores, and the unevenness of the depth.

As is clear from Table 1, in Examples 1 to 5, a mold having an oxide film with little pore depth unevenness could be produced.
Further, it was found that even when the maximum voltage in the step (a) is the same, the unevenness of the pore depth varies greatly depending on the voltage in the step (c). In particular, when using an oxalic acid electrolyte, the degree of unevenness of the depth changed abruptly between the voltage in step (c) of 90 V or more and less than 90 V. Moreover, when using the phosphoric acid electrolyte, the degree of unevenness of the depth changed rapidly between the voltages in the step (c) of 150 V or more and 130 V or less.
Further, as apparent from FIGS. 5 and 6, even in the case of a transfer product having the same protrusion height, in the case of FIG. I found it big.

  The method for producing a mold and the method for producing an article having a fine concavo-convex structure on the surface thereof are useful for efficient mass production of antireflection articles, antifogging articles, antifouling articles, and water repellent articles.

DESCRIPTION OF SYMBOLS 10 Aluminum base material 12 Pore 14 Oxide film 18 Mold 20 Roll-shaped mold 40 Article 42 Film 46 Convex part

Claims (5)

A method for producing a mold in which an oxide film having a plurality of pores is formed on the surface of an aluminum substrate,
The manufacturing method of a mold which has the following process (a)-process (e).
(A) A step of anodizing the surface of the aluminum substrate to form an oxide film.
(B) A step of removing the oxide film formed in the step (a).
(C) A step of forming an oxide film having a plurality of pores after the step (b) by anodizing the aluminum substrate at a voltage less than 90% of the maximum voltage applied in the step (a).
(D) A step of expanding the pore diameter after the step (c).
(E) A step of alternately repeating the step (c) and the step (d).   The method for producing a mold according to claim 1, wherein in the step (a), anodization is performed at a voltage of 90 V or more.   2. The mold according to claim 1, wherein in the step (a), after anodizing is started at a voltage of less than 90 V, the voltage is increased stepwise or continuously, and finally anodized at a voltage of 90 V or more. Manufacturing method.   A fine concavo-convex structure formed by transferring a fine concavo-convex structure composed of a plurality of pores formed on the surface of the mold obtained by the method for producing a mold according to claim 1 to the surface of the article body. A method for manufacturing an article. An aluminum base and an oxide film having a plurality of pores formed on the surface of the aluminum base,
A mold in which an average interval between the plurality of pores is 180 nm or more, and a variation in depth of the plurality of pores is 50 nm or less.

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