JP2015101780A - Mold-manufacturing method, and compact having fine uneven structure on surface and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold-manufacturing method capable of easily and well-productively manufacturing a mold where an oxide film having plural pores is formed on the surface of an aluminum base material and also manufacturing a mold excellent in durability; and a compact having a fine uneven structure on the surface and a manufacturing method thereof.SOLUTION: A method of manufacturing a mold where an oxide film having plural pores is formed on the surface of an aluminum base material has a step (a) of immersion of an aluminum base material in a phosphoric acid electrolyte to apply voltage and anodic oxidation of the surface of the aluminum base material to form an oxide film, and a step (b) of keeping the aluminum base material immersed in the phosphoric acid electrolyte without substantial application of voltage after the step (a), and at least some of the oxide film formed in the step (a) is removed. The concentration of the phosphoric acid electrolyte is 0.05 mol/L or more and 2.5 mol/L or less, and the solution temperature is 18°C or more and 45°C or less.

Description

  The present invention relates to a method for producing a mold, a molded body having a fine concavo-convex structure on the surface, and a method for producing the same.

  In recent years, it has become possible to impart a nanoscale fine concavo-convex structure to the surface of a molded body due to advances in microfabrication technology. Nanoscale fine concavo-convex structure exhibits industrial functions such as antireflection function called moth-eye effect and water repellent function called lotus effect. There are a lot of studies to do.

There are various techniques for imparting a fine relief structure to the surface of the molded body. Among these, the method of transferring the fine concavo-convex structure formed on the surface of the mold to the surface of the molded body is suitable for industrial production because the fine concavo-convex structure can be imparted to the surface of the molded body with simple and few steps. . In recent years, as a method for easily producing a large-area mold having a fine concavo-convex structure on the surface, a method utilizing an oxide film (anodized porous alumina) having a plurality of pores by anodizing an aluminum base material has attracted attention. Has been.
In an oxide film formed by anodization, the interval (pitch) between pores tends to increase in proportion to the applied voltage during anodization. The method is also suitable as a method for producing a mold because the interval between the pores can be controlled relatively easily.

In order to manufacture a mold having a suitable depth and an oxide film having regularly arranged pores, a method of performing anodization in two stages using anodization is suitable. Yes. That is, the following steps (i) to (iii) are sequentially performed to obtain pores suitable for the mold.
Step (i): A step of anodizing the surface of the aluminum base material and arranging the pores regularly ignoring the depth of the pores.
Step (ii): A step of removing part or all of the oxide film formed in step (i).
Step (iii): After step (ii), the aluminum substrate is anodized again to form pores of arbitrary depth while maintaining a regular arrangement.

  In particular, in the step (iii), if etching that expands the pore diameter of the pores formed by anodization is used in combination, the pores can be arbitrarily tapered and the ridges of the pores are stepped by repeating the anodization and etching. It can be adjusted to a substantially conical shape.

By the way, when manufacturing a mold using anodic oxidation, in order to precisely design the shape of the pores, the chemical type, concentration, etc. of the treatment liquid (electrolytic solution and etching solution) usually used for anodic oxidation and etching, Design temperature and temperature separately. That is, separate treatment liquids are required for anodic oxidation and etching.
However, the use of separate treatment liquids for anodization and etching not only increases the number of treatment tanks in which treatment liquids are stretched, but also installs temperature control equipment and cleaning equipment attached to each treatment, as well as those. Space is also required, which is extremely disadvantageous from the viewpoint of industrialization. Moreover, when the movement between the processing tanks of an aluminum base material is considered, productivity is also inferior.

An example in which anodization and etching are performed with the same processing solution has been reported so far.
For example, Patent Document 1 discloses a method for producing a mold of an optical element by anodic oxidation. In Patent Document 1, aluminum is immersed in a phosphoric acid aqueous solution, and anodization and etching are switched depending on whether or not energization is applied.
Patent Document 2 discloses a method of manufacturing a mold of an optical element by immersing an aluminum base material in a phosphoric acid aqueous solution and adjusting the shape of the pores by repeating the presence or absence of applied current.
Patent Document 3 discloses a method of manufacturing a mold by immersing a mold base material in a processing solution and switching and executing anodization and etching only by switching an applied voltage.

JP 2012-58424 A JP 2013-7886 A JP 2013-130819 A

However, in practice, the methods described in Patent Documents 1 to 3 do not sufficiently expand the pore diameter (the diameter of the opening of the pore) compared to the case where anodization and etching are performed with separate treatment liquids. There was a problem in the durability as a mold, for example, when a fine concavo-convex structure formed on the surface of the mold was transferred to the surface of the molded body, a mold release failure was likely to occur. In addition, it is difficult to balance the current density that flows when voltage is applied and the time required to expand the pore diameter, and the productivity of the mold tends to decrease.
As described above, when the anodic oxidation and the etching are performed with the same processing solution, the mold cannot always be easily produced.

Further, in Patent Document 1, a mold having a pore pitch exceeding 400 nm is produced. However, since the pore pitch tends to be proportional to the voltage in anodization, it is suitable for obtaining a pitch of 400 nm or more. High voltage equipment is necessary and not economical. In addition, a fine concavo-convex structure having a pitch exceeding 400 nm is transferred to the surface of a molded body obtained using this mold. However, when the pitch exceeds 400 nm, visible light is easily scattered, and the antireflection performance and the like are impaired. There was a fear.
Patent Document 2 does not mention a preferable type or temperature / concentration range regarding the treatment liquid. In the example of Patent Document 2, a 5% by weight phosphoric acid aqueous solution at 10 ° C. is used, but under these conditions, the current density at 60 V applied is small and the etching rate is remarkably slow, so the mold productivity is poor. Further, in a mold having a small pore diameter, the resin hardly enters the pores at the time of transfer, and the transferability of the mold tends to be inferior. In addition, when the cured resin is released from the mold, if the pore diameter is small, the resin remains in the pores, which tends to cause a release failure.
Patent Document 3 does not mention conditions satisfying both durability and productivity as a mold, particularly anodic oxidation conditions and etching conditions.

  The present invention has been made in view of the above circumstances, and can easily and efficiently produce a mold in which an oxide film having a plurality of pores is formed on the surface of an aluminum substrate, and produce a mold having excellent durability. An object of the present invention is to provide a mold manufacturing method, a molded article having a fine concavo-convex structure on the surface, and a method for manufacturing the same.

  As a result of intensive studies, the present inventors have studied various conditions of the electrolytic solution during anodization, so that not only has an appropriate etching rate when voltage is not applied, but also anodized in a low voltage range of several tens of volts. When the current density was found to flow properly. Therefore, while carrying out anodization and etching with the same processing solution (electrolyte), the present inventors have found a mold manufacturing condition that is excellent in durability without impairing mold productivity and completed the present invention. It was.

That is, this invention has the following aspects.
[1] 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, comprising the following steps (a) and (b), and the following phosphoric acid electrolyte The manufacturing method of the mold whose density | concentration is 0.05 mol / L or more and 2.5 mol / L or less and whose liquid temperature is 18 degreeC or more and 45 degrees C or less.
Step (a): A step of immersing an aluminum base material in a phosphoric acid electrolyte and applying a voltage to anodize the surface of the aluminum base material to form an oxide film.
Step (b): After the step (a), the aluminum substrate is immersed in a phosphoric acid electrolyte solution and held without applying a voltage, and the oxide film formed in the step (a) Removing at least a portion.
[2] The method for producing a mold according to [1], wherein in the step (a), a voltage applied to the aluminum substrate is 20 V or more and 150 V or less.
[3] A mold is manufactured by the method for manufacturing a mold according to [1] or [2], and a fine uneven structure including a plurality of pores formed on the surface of the mold is transferred to the surface of the molded body. A method for producing a molded article having a fine relief structure on its surface.
[4] A molded body having a fine concavo-convex structure on the surface, wherein the fine concavo-convex structure is formed on the surface of a mold obtained by the mold manufacturing method according to [1] or [2]. A molded article having a fine concavo-convex structure on the surface, which is an inverted structure of the fine concavo-convex structure comprising holes.

  According to the present invention, a mold manufacturing method capable of manufacturing a mold in which an oxide film having a plurality of pores is formed on the surface of an aluminum base simply and with high productivity, and capable of manufacturing a mold excellent in durability, and A molded body having a fine concavo-convex structure on the surface and a method for producing the same can be provided.

It is sectional drawing which shows the manufacturing process of the mold which has an anodized alumina on the surface. It is a block diagram which shows an example of the manufacturing apparatus of the molded object which has a fine concavo-convex structure on the surface. It is sectional drawing which shows an example of the molded object which has a fine concavo-convex structure on the surface.

Hereinafter, the present invention will be described in detail.
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.
Further, the “projection” refers to a convex portion having a fine concavo-convex structure formed on the surface of the molded body.
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” is a generic term for acrylate and methacrylate, “(meth) acrylic acid” is a generic term for acrylic acid and methacrylic acid, and “(meth) acrylonitrile” is a generic term for acrylonitrile and methacrylonitrile. “(Meth) acrylamide” is a general term for acrylamide and methacrylamide.
“Active energy rays” mean visible light, ultraviolet rays, electron beams, plasma, heat rays (infrared rays, etc.) and the like.
Further, “transparent” means transmitting at least light having a wavelength of 400 to 760 nm.

"Mold manufacturing method"
The mold manufacturing method of the present invention includes the following steps (a) and (b). Moreover, it is preferable to have the following process (c) after a process (b).
Step (a): A step of immersing an aluminum base material in a phosphoric acid electrolyte and applying a voltage to anodize the surface of the aluminum base material to form an oxide film.
Step (b): After the step (a), the aluminum substrate is immersed in a phosphoric acid electrolyte solution and held without applying a voltage, and the oxide film formed in the step (a) Removing at least a portion.
Step (c): A step of alternately repeating the step (a) and the step (b).
Hereinafter, each step will be described in detail.

<Process (a)>
Step (a) is a step of forming an oxide film by immersing an aluminum base material in a phosphoric acid electrolyte and applying a voltage to anodize the surface of the aluminum base material.
The shape of the aluminum substrate 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.
As an aluminum base material, what the aluminum base material surface is a mirror surface is preferable. If the surface of the aluminum substrate is a mirror surface, the transparency is hardly impaired even when used as a mold for a transparent molded body. The means for mirroring the surface of the aluminum substrate is not particularly limited. For example, a method of physically cutting or polishing the surface of the aluminum substrate; a method of electropolishing the aluminum substrate; a method of chemically polishing the aluminum substrate; Combinations of these are included.

  The purity of the aluminum substrate is preferably 98% by mass or more, more preferably 99.0% by mass or more, further preferably 99.5% by mass or more, and most preferably 99.9% by mass or more. When the purity of aluminum is low, when anodized, an uneven structure having a size to scatter visible light may be formed due to segregation of impurities, or the regularity of pores obtained by anodization may be lowered.

  By the way, when high-purity aluminum is used, when processing into a desired shape (for example, a cylindrical shape), aluminum may be too soft and difficult to process. Therefore, an aluminum base material that is processed into a predetermined shape by adding magnesium to aluminum may be used. By adding magnesium, the strength of aluminum is increased, which makes it easier to process. However, as the amount of magnesium added increases, the haze of the molded body obtained by transferring the fine concavo-convex structure of the obtained mold to the surface of the molded body tends to increase. Therefore, it is preferable to determine the addition amount of magnesium in consideration of the strength of aluminum and the haze of the molded body, and usually about 0.1 to 2% by mass is preferable with respect to the total mass of the aluminum substrate.

  In step (a), the aluminum substrate is anodized using a phosphoric acid electrolyte in a treatment tank. The phosphoric acid electrolyte easily balances the reaction rate of anodic oxidation when a voltage is applied and the dissolution rate of the oxide film when no voltage is applied in the following step (b). Oxidation (step (a)) and etching (step (b)) can be performed. That is, the phosphoric acid electrolytic solution can also serve as an etching solution, and is suitable for manufacturing a mold simply and with high productivity.

  The temperature of the phosphoric acid electrolyte is 18 ° C. or higher and 45 ° C. or lower, and preferably 20 ° C. or higher and 40 ° C. or lower. When the temperature of the phosphoric acid electrolyte is lower than 18 ° C., the etching rate in the following step (b) becomes insufficient, the mold manufacturing time becomes remarkably long, and the productivity of the mold decreases. Further, since the diameter of the pores formed on the mold surface is small even after the following step (b), a transfer defect is likely to occur when used as a mold. On the other hand, when the temperature of the phosphoric acid electrolyte is higher than 45 ° C., the voltage range applicable in the step (a) is narrowed. Therefore, for example, when anodization is performed at a high voltage, a phenomenon called “burning” in which a very high current density flows instantaneously is caused, and the pores are easily broken or the appearance of the mold is easily damaged. Moreover, the concentration of the phosphoric acid electrolyte may change due to evaporation of the solvent.

The concentration of the phosphoric acid electrolyte is 0.05 mol / L or more and 2.5 mol / L or less. If the concentration of the phosphoric acid electrolyte is lower than 0.05 mol / L, the reaction rate (anodization rate) in the step (a) is slow and the productivity is lowered. Further, since the diameter of the pores formed on the mold surface is small even after the following step (b), a transfer defect is likely to occur when used as a mold. On the other hand, when the concentration of the phosphoric acid electrolyte is higher than 2.5 mol / L, the voltage range applicable in the step (a) is narrowed. For this reason, for example, when anodization is performed at a high voltage, “burning” occurs, and the pores are broken or the appearance of the mold is easily damaged.
Although it does not restrict | limit especially as a solvent of phosphoric acid electrolyte solution, Water, alcohol, ether, etc. are mentioned.

  The applied voltage in the step (a) is preferably 20 V or more and 150 V or less, more preferably 30 V or more and 100 V or less, and further preferably 40 V or more and 80 V or less. In particular, when the applied voltage is 40 V or more, an oxide film having a relatively large pore interval (over 100 nm) can be easily formed. On the other hand, if the voltage is 150 V or less, pores can be formed at an interval smaller than the wavelength of visible light, and thus it is possible to suppress an increase in the haze of the molded body to which the fine concavo-convex structure of the obtained mold is transferred.

  The energization time in the step (a) is preferably 5 seconds or more and 60 seconds or less. If the energization time is 5 seconds or more, the thickness of the finally obtained oxide film is easily set to 80 nm or more, which will be described later. When the oxide film has a thickness of less than 80 nm, the depth of the pores is less than 80 nm, and when used as a mold, the resulting molded product may not exhibit sufficient antireflection performance. On the other hand, if the energization time is 60 seconds or less, the thickness of the finally obtained oxide film can be easily set to 0.8 μm or less, which will be described later. In the case of an oxide film having a thickness of more than 0.8 μm, the pores become deeper as the oxide film becomes thicker. Therefore, when it is used as a mold, there is a risk of causing a mold release failure.

In step (a), the current density for 10 seconds immediately after the voltage application, that is, after the voltage application is started, may be 20 mA / cm ² or less, more preferably 10 mA / cm ² or less. Setting the current density immediately after voltage application to 20 mA / cm ² or less means that current jumping is suppressed, and white turbidity on the mold surface can be suppressed. As a result, it is possible to more effectively suppress an increase in the haze of the molded body to which the fine concavo-convex structure of the obtained mold is transferred, and a molded body having a lower reflectance can be obtained.

  By the way, even at the same concentration and the same applied voltage, the reaction on the surface of the aluminum substrate may be difficult to proceed uniformly if the temperature of the electrolytic solution changes. Further, when anodization is performed by applying a voltage, the temperature of the electrolytic solution tends to increase due to Joule heat due to the applied voltage and the amount of current flowing. When the temperature of the electrolyte changes, the electric conductivity also changes, which may cause the current density to fluctuate. Therefore, it is preferable to keep the temperature of the phosphoric acid electrolyte constant within the above range during anodic oxidation.

Phosphoric acid is an electrolyte that is typically used in anodization of aluminum. However, when anodization is performed using a phosphoric acid electrolyte, it is intended to form highly regular pores. In general, anodization is performed in a low temperature range of 0 to 5 ° C., for example, under conditions of a voltage of 195 V.
On the other hand, it can be said that the conditions of the anodic oxidation in the step (a) are largely separated from the general conditions as described above for both the temperature and the applied voltage. Generally, when anodization is performed using phosphoric acid as an electrolytic solution, current does not flow easily and the progress of anodization becomes very slow. For this reason, it is common practice to apply a high voltage to facilitate the flow of current. However, when a high voltage is applied, the heat generated by the aluminum base material increases, so the electrolyte solution is maintained at a low temperature, It was necessary to suppress thermal runaway.
However, in the present invention, by setting the concentration of the phosphoric acid electrolyte used as the electrolyte to a specific range of 0.05 to 2.5 mol / L, a temperature higher than the low temperature range of 0 to 5 ° C. (that is, The anodic oxidation of the step (a) can be performed at 18 ° C. or higher and 45 ° C. or lower). In particular, if the applied voltage is significantly lowered from a generally known range of 20 to 150 V, the anodization in step (a) can be more easily performed at a temperature higher than the low temperature range.

<Step (b)>
In the step (b), after the step (a), the aluminum substrate is immersed in a phosphoric acid electrolyte solution and held without applying a voltage, and the oxide film formed in the step (a). Is a step of removing at least a part of
When the step (b) is performed after the step (a), that is, the application of voltage is interrupted after the step (a), and the aluminum substrate is held in the phosphoric acid electrolyte in the same treatment tank as in the step (a). As a result, part of the oxide film formed in the step (a) is removed, and the pore diameter is increased. Therefore, the step (b) is also a hole diameter enlargement processing step.
Here, “the voltage is not substantially applied” and “the voltage application is interrupted” not only means that the voltage applied to the aluminum substrate is 0 V, but also the current does not flow through the aluminum substrate and the oxide film. This also includes reducing the voltage to such an extent that the formation of is not progressed.

  The longer the time of step (b), that is, the longer the time for immersing the aluminum substrate in the phosphoric acid electrolyte without applying voltage, the larger the pore diameter tends to be. However, if the time is too long, the oxide film is completely dissolved and the pores disappear. Since the gap between the pores generated in the oxide film also fluctuates due to the applied voltage in step (a), that is, the thickness of the wall separating adjacent pores fluctuates, the time of step (b) is generally Although not determined, in consideration of mold productivity, it is preferably within 30 minutes, more preferably within 20 minutes, and even more preferably within 10 minutes.

  The temperature of the phosphoric acid electrolyte in the step (b) may be the same as or different from the temperature of the phosphoric acid electrolyte in the step (a) as long as it is 18 ° C. or higher and 45 ° C. or lower. Further, during the step (b), it is preferable to keep the temperature of the phosphoric acid electrolyte constant within the above range.

<Step (c)>
Step (c) is a step in which the step (a) and the step (b) are alternately repeated.
When step (a) is performed after step (b), a new oxide film is formed under the existing oxide film, and new pores extending downward from the bottom of the existing pores are formed.
By alternately repeating the step (a) and the step (b), the shape of the pores can be changed to a tapered shape in which the diameter gradually decreases in the depth direction from the opening, and as a result, a plurality of periodic pores A mold having an oxide film formed on the surface can be obtained.

  Ranges described above for the conditions of the step (a) and the step (b), for example, the temperature and concentration of the anodic oxidation phosphoric acid electrolyte, the oxidation time, the time of the pore diameter expansion treatment, and the temperature of the phosphoric acid electrolyte during the pore diameter expansion treatment By appropriately setting the inside, it is possible to form oxide films having pores of various shapes. What is necessary is just to set these conditions suitably according to the use etc. of the molded object manufactured using a mold.

The number of times of the step (a) is preferably at least 3 times including the step (a) performed before the step (c), since the larger the number of times, the smoother the pores can be made. Similarly, the number of times of the step (b) is preferably at least 3 times including the step (b) performed before the step (c) because the pores can be formed into a smooth taper shape as the number of times increases. . When the number of times is less than 2 times, the pore diameter tends to decrease discontinuously. When an antireflection article (such as an antireflection film) is manufactured using such a mold, the reflectance is reduced. The effect may be inferior.
Step (c) may be completed in step (a) or may be completed in step (b).

  Deeper pores can be obtained as the anodic oxidation in the step (a) and the step (c) is performed for a longer time, but when used as a mold for transferring the fine concavo-convex structure, it is finally obtained through the step (c). The thickness of the oxide film to be formed may be about 80 nm or more and 0.8 μm or less. Further, when repeating step (a) and step (b), it is not necessary to carry out under the same conditions as the previous steps, and various conditions may be changed as appropriate within the above-mentioned range. .

  Further, the longer the hole diameter expansion process in the step (b), the longer the manufacturing time of the mold. However, even if it is too short, the hole diameter is not sufficiently expanded, making it difficult to use as a mold. In other words, when the pore diameter is not sufficiently expanded, the diameter of the formed pore (the diameter of the opening of the pore) is small, so that the resin is difficult to enter the pore at the time of transfer, and the mold transferability may deteriorate. is there. In addition, when the cured resin is released from the mold, if the pore diameter is small, the resin remains in the pores, which tends to cause a release failure. These problems are less likely to occur as the pore diameter is larger, but if the average pore diameter is 60 nm or more, it can withstand practical use as a mold.

<Other processes>
In the mold manufacturing method of the present invention, the following steps (α) and (β) may be performed as a pretreatment step of the step (a).
Step (α): A step of immersing the aluminum base material in an electrolytic solution, applying a voltage, and anodizing the surface of the aluminum base material to form an oxide film.
Step (β): A step of removing at least a part of the oxide film formed in the step (α) to form pore generation points for anodic oxidation.

The pretreatment step is a step of forming a pore generation point on the surface of the aluminum base material, that is, a starting point for inducing the generation of pores at the location.
The oxide film formed at the initial stage of anodization has non-uniformity in the position and size of the pores, and there is no regularity. However, as the oxide film becomes thicker, the regularity of the pore arrangement gradually increases. Go. If the pore generation points are formed in advance, especially when the pore generation points are regularly arranged, even at the initial stage of anodic oxidation, that is, even when the formed oxide film is thin, it is regularly Arranged pores are formed, the depth of the pores is adjusted on the order of submicrons, and regularly arranged pores can be easily manufactured.

(Process (α))
Examples of the electrolytic solution used in the step (α) 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. .

When using phosphoric acid as electrolyte:
In the step (α), when phosphoric acid is used as the electrolytic solution, the concentration of phosphoric acid is preferably 0.05 mol / L or more and 2.5 mol / L or less. If the concentration of oxalic acid exceeds 2.5 mol / L, the current value may become too high and the surface of the oxide film may become rough, or burns may occur and the oxide film may be destroyed. . When the concentration of phosphoric acid is less than 0.05 mol / L, the reaction rate (anodization rate) is slow, and productivity may be reduced.
The temperature of the electrolytic solution is preferably 40 ° C. or lower, more preferably 30 ° C. or lower, and further preferably 20 ° C. or lower. When the temperature of the electrolytic solution exceeds 40 ° C., a so-called “burn” phenomenon occurs, and the pores may be broken, or the surface may melt and the regularity of the pores may be disturbed.

When using oxalic acid as electrolyte:
In the step (α), when oxalic acid is used as the electrolytic solution, the concentration of oxalic acid is preferably 0.7 mol / L or less. When the concentration of oxalic acid exceeds 0.7 mol / L, the current value becomes too high, and the surface of the oxide film may become rough.
The temperature of the electrolytic solution is preferably 60 ° C. or lower, and more preferably 45 ° C. or lower. When the temperature of the electrolytic solution exceeds 60 ° C., a so-called “burn” phenomenon occurs, and the pores may be broken or the surface may melt and the regularity of the pores may be disturbed.

When using sulfuric acid as the electrolyte:
In the step (α), when sulfuric acid is used as the electrolytic solution, the concentration of sulfuric acid is preferably 0.7 mol / L or less. If the concentration of sulfuric acid exceeds 0.7 mol / L, the current value may become too high to maintain a constant voltage.
The temperature of the electrolytic solution is preferably 30 ° C. or less, and more preferably 20 ° C. or less. When the temperature of the electrolytic solution exceeds 30 ° C., a so-called “burn” phenomenon occurs, and the pores may be broken, or the surface may melt and the regularity of the pores may be disturbed.

  In the step (α), the voltage value applied to the aluminum substrate and the conditions at the time of application may be the same as those in the step (a). Further, since the thickness of the oxide film is proportional to the integrated electric quantity that is the product of the current density and the oxidation time, the voltage, current density, and oxidation time may be appropriately changed according to the thickness of the oxide film to be formed. The time for applying the voltage to the aluminum substrate is preferably 5 minutes or more and 120 minutes or less from the viewpoint of mold productivity.

The thickness of the oxide film formed in the step (α) is preferably 0.5 μm or more and 10 μm or less. If the thickness of the oxide film is within this range, when the oxide film is removed in the step (β) described later, the machining marks on the surface of the aluminum base material are sufficiently removed, and the step of the crystal grain boundary is removed. Is not so large as to be visually recognized, it is possible to avoid transfer of macro unevenness derived from the mold to the surface of the molded body.
The thickness of the oxide film formed in the step (α) is proportional to the total amount of electricity consumed in the anodic oxidation. By adjusting the ratio of the total amount of electricity and the amount of electricity consumed for each voltage, the thickness ratio of the oxide film and the thickness of the oxide film formed by the initial anodic oxidation can be controlled.

(Process (β))
Step (β) is an oxide film removal step for removing at least a part of the oxide film formed in step (α). In the step (β), as a method for removing part or all of the oxide film, a method of immersing in a solution that selectively dissolves alumina (oxide film) without dissolving aluminum can be mentioned. Examples of such a solution include a chromic acid / phosphoric acid mixed solution.

  In the step (β), the time for immersing the aluminum substrate in the solution may be appropriately adjusted according to the thickness of the oxide film to be removed and the concentration of chromic acid / phosphoric acid, from the viewpoint of mold productivity. It is preferable that it is 15 to 300 minutes.

Hereinafter, the manufacturing method of the mold of the present invention including the steps (a) and (b) will be described in detail with reference to FIG. Here, a manufacturing method in the case of including the above-described steps (c), (α), and (β) will be described.
First, a voltage is applied to the machined aluminum substrate 10, and the surface of the aluminum substrate is anodized to form an oxide film (step (α)). The pores formed in the initial stage of the step (α) have low regularity and randomly generate pores. However, when anodization is performed for a long time, the pore arrangement period gradually increases as the pores become deeper. Regularity is getting higher. Thereby, for example, as shown in FIG. 1, an oxide film 14 having a plurality of pores 12 arranged with high regularity can be formed on the surface of the aluminum substrate 10. Further, after the step (α), at least a part of the anodized film such as the upper part of the pores in which the pores are randomly generated or all the anodized film is removed (step (β)), for example, in FIG. As shown, an oxide film 14 having a plurality of depressions 16 arranged with high regularity can be formed on the surface of the aluminum substrate 10.
By using the aluminum base material in which a plurality of depressions 16 are formed and performing the above steps (a) and (b), a mold in which the depressions 16 act as pore generation points and the pores are arranged more regularly. Can be manufactured.

Specifically, first, when an aluminum substrate 10 having a plurality of depressions 16 formed therein is immersed in a phosphoric acid electrolyte and anodized by applying a voltage, as shown in FIG. The material 10 is anodized, and an oxide film 14 having a plurality of pores 12 is formed again (step (a)).
And the application of the voltage to the aluminum base material 10 is interrupted, and by holding the aluminum base material 10 in the phosphoric acid electrolyte in the same treatment tank, as shown in FIG. A part is removed, and the pore diameter of the pores 12 is expanded (step (b)).
Furthermore, the step (a) of applying a voltage and the step (b) of interrupting the application of the voltage and holding the aluminum substrate 10 immersed in the phosphoric acid electrolyte solution are alternately repeated (step ( c)) As shown in FIG. 1, the shape of the pores 12 can be a tapered shape whose diameter gradually contracts in the depth direction from the opening. As a result, it is possible to obtain a mold 18 in which an oxide film 14 composed of a plurality of periodic pores 12 is formed on the surface of the aluminum substrate 10.

<Effect>
In the mold manufacturing method of the present invention described above, by specifying the type, concentration, and temperature of the electrolytic solution used for anodization, both the anodization rate and the etching rate are within a suitable range in one treatment tank. can do. Therefore, according to the present invention, after the anodic oxidation process is completed, the work of lifting the aluminum base material from the treatment tank and immersing it in another treatment tank to perform etching becomes unnecessary, and the manufacturing process and the apparatus are simplified. Is possible. In addition, while performing anodization and etching with the same processing solution, it is possible to manufacture a mold having excellent durability that does not cause mold release defects without impairing the productivity of the mold.
Note that the above-described pretreatment steps (steps (α) and (β)) are not included in the anodic oxidation and etching described here.

"mold"
According to the mold manufacturing method of the present invention, tapered pores whose diameter gradually decreases from the opening in the depth direction are formed on the surface of the aluminum base material in a relatively regular arrangement. A mold having an oxide film (anodized porous alumina) having a fine relief structure formed on the surface can be produced.

The average interval between adjacent pores of the mold thus obtained is preferably not more than the wavelength of visible light, more preferably not less than 100 nm and not more than 400 nm. When the average interval between the pores is 100 nm or more, the scratch resistance can be improved without impairing the antireflection performance of a molded article (antireflection article or the like) obtained by transferring the surface of the mold. And the whitening of the molded object resulting from unity of protrusions can be suppressed. On the other hand, if the average interval between the pores is 400 nm or less, it is difficult for visible light to scatter on the surface (transfer surface) of the molded body obtained by transferring the surface of the mold, and a sufficient antireflection function is exhibited. Suitable for the production of antireflection articles such as antireflection films.
The average pore spacing is obtained by measuring 50 intervals between adjacent pores (distance from the center of the pore to the center of the neighboring pore) by electron microscope observation, and averaging these values.

In addition, when the mold is used for the production of an antireflection article (antireflection film or the like), the average interval between the pores is 400 nm or less, and the average depth of the pores is preferably 80 nm or more, preferably 100 nm or more. It is more preferable that the thickness is 150 nm or more. When a mold having an average pore depth of less than 80 nm is used, the antireflection performance of the antireflection article may be insufficient.
Further, the aspect ratio (= average depth / average interval) of the pores of the mold is preferably 0.25 or more, more preferably 0.5 or more, and most preferably 0.75 or more. When the aspect ratio is 0.25 or more, a surface with low reflectance can be formed, and the incident angle dependency thereof is sufficiently small.
The average depth of the pores was determined by measuring 50 vertical distances between the lowest part of the pores and the highest part of the convex portions existing between the pores when observed at an magnification of 30000 by electron microscope observation. These values are averaged.

  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 phosphate ester polymer, a silicone polymer, a fluorine polymer, etc .; a method of depositing a fluorine compound; a coating of a fluorine surface treatment agent or a fluorine silicone surface treatment agent. The method etc. are mentioned.

  Moreover, if the mold obtained by the manufacturing method of the mold of this invention is used, the molded object which has a fine uneven structure on the surface can be obtained in large quantities from one mold.

"Method of manufacturing molded body"
The method for producing a molded article having a fine concavo-convex structure on the surface of the present invention is a mold produced by the mold production method of the present invention, and a fine concavo-convex structure comprising a plurality of pores formed on the surface of the mold, This is a method of transferring to the surface of the molded body.
In the molded body produced by transferring the fine concavo-convex structure (pores) of the mold, the inverted structure (protrusion) 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 molded body, for example, an uncured active energy ray-curable resin composition is filled between the mold and the molded body (transparent substrate), and the mold In a state where the active energy ray-curable resin composition is in contact with the fine concavo-convex 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, the molded object by which the fine concavo-convex structure which consists of hardened | cured material of an active energy ray curable resin composition was formed in the surface of a molded object main body can be manufactured. The fine concavo-convex structure of the obtained molded body is an inverted structure of the fine concavo-convex structure of the mold.

<Molded body>
The molded body (transparent substrate) is preferably one that does not significantly inhibit the irradiation of active energy rays because the irradiation of active energy rays is performed through the molded body. Examples of the material of the molded body include polyester resins (polyethylene terephthalate, polybutylene terephthalate, etc.), polymethacrylate resins, polycarbonate resins, vinyl chloride resins, ABS resins, styrene resins, and glass.

<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, the active energy ray-curable resin composition is supplied between the mold and the molded body (transparent substrate) and then rolled and filled; active energy ray curing Examples include a method of laminating a molded body main body on a mold coated with a curable resin composition; a method of previously laminating an active energy ray-curable resin composition on a molded body body and laminating the mold body.

  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 a monomer 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) acrylates, polyol (meth) acrylates, epoxy (meth) acrylates, urethane (meth) acrylates, cationic polymerization type epoxy compounds, homopolymers of the above-mentioned monomers having radically polymerizable bonds in the side chains, and the like 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, etc.), sulfur compounds (tetramethylthiuram monosulfide, tetramethylthiuram disulfide, etc.), 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,4) - trimethyl benzoyl) - phenyl phosphine oxide, such as benzo dichloride ethoxy phosphine oxide. 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, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, etc.), methylbenzoylformate 1,7-bisacridinyl heptane, 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 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polymerization reactive compound. When the active energy ray polymerization initiator is less than 0.1 part by mass, the polymerization is difficult to proceed. On the other hand, 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.

Examples of the non-reactive polymer include acrylic resins, styrene resins, polyurethane resins, cellulose resins, polyvinyl butyral resins, polyester resins, and thermoplastic elastomers.
Examples of the active energy ray sol-gel reactive composition include an alkoxysilane compound and an alkyl silicate compound.

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>
A molded body 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 curability from the tank 22 between a roll-shaped mold 20 having a fine concavo-convex structure (not shown) on the surface and a strip-shaped film 42 (molded body) that moves 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, a molded body 40 as shown in FIG. 3 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.

<Molded body>
As shown in FIG. 3, the molded body 40 manufactured in this way has a cured resin layer 44 formed on the surface of a film 42 (molded body).
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.
When the mold obtained by the present invention is used, the fine uneven structure on the surface of the molded body 40 is formed by transferring the fine uneven structure on the surface of the oxide film, and is an active energy ray-curable resin composition. And a plurality of protrusions 46 made of a cured product.

  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.

(Use)
The molded product having the fine concavo-convex structure of the present invention on the surface exhibits various performances such as antireflection performance and water repellency performance by the fine concavo-convex structure on the surface.
When the molded body having a fine concavo-convex structure on the surface is in the form of a sheet or film, as an antireflection film, for example, an object such as an image display device (TV, mobile phone display, etc.), display panel, meter panel, etc. It can be used by sticking to the surface or insert molding. In addition, taking advantage of its water-repellent performance, it can also be 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, and glasses lenses. Can be used.
When the molded body having a fine concavo-convex structure on its surface is a three-dimensional shape, an antireflection article is manufactured using a molded body (transparent substrate) having a shape according to the application, and this is applied to the surface of the object. It can also be used as a member that constitutes.

Further, when the object is an image display device, not only the surface thereof but also a molded body 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 be comprised from the molded object which has an uneven | corrugated structure on the surface. For example, the surface of a rod lens array attached to a sensor array that reads an image, a cover glass of an image sensor such as a FAX, a copying machine, or a scanner, or a contact glass on which a document of a copying machine is placed has a fine uneven structure on the surface. The body may be used. Further, by using a molded body 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.
Moreover, the molded object which has a fine concavo-convex structure on the surface can be developed for optical uses such as an optical waveguide, a relief hologram, an optical lens, and a polarization separation element, and for use as a cell culture sheet, in addition to the uses described above.

  In addition, the molded object which has a fine uneven structure on the surface is not limited to the molded object 40 of the example of illustration. For example, the fine concavo-convex structure may be directly formed on the surface of the film 42 by the thermal imprint method without providing the cured resin layer 44. However, the fine uneven structure is preferably formed on the surface of the cured resin layer 44 from the viewpoint that the fine uneven structure can be efficiently formed using a roll-shaped mold.

<Effect>
In the method for producing a molded article having a fine concavo-convex structure on the surface according to the present invention described above, the mold is produced by the mold production method of the present invention, and the fine concavo-convex structure formed on the surface of the mold is formed. Since it is transferred onto the surface of the body main body, a molded body having a low haze and a sufficiently reduced reflectance can be produced.
Moreover, according to this invention, the molded object which has the reverse structure of the fine concavo-convex structure of this mold on the surface can be simply manufactured in one process by using the mold obtained with the manufacturing method of the mold of this invention.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

<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 accelerating voltage is measured using a field emission scanning electron microscope (“JSM-6701F” manufactured by JEOL Ltd.). The observation was magnified 10,000 times at 3.00 kV. 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.
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. Each cross-section sample was observed by magnifying it by 2 to 50,000 times, and the depth of five pores and the pore diameter in the vicinity of the oxide film surface (diameter of the opening) were measured and averaged. The average pore depth and average pore diameter were calculated.

<Measurement of protrusions on molded body>
Platinum is vapor-deposited on the surface and longitudinal section of the molded body (film) for 10 minutes and molded under the condition of an acceleration voltage of 3.00 kV using a field emission scanning electron microscope (manufactured by JEOL Ltd., “JSM-6701F”). The surface and cross section of the body were observed.
The surface of the molded body was magnified 10,000 times and observed, and the average distance (pitch) between the projections was obtained by averaging the distances between the centers of the six projections (convex portions) arranged in a straight line. Moreover, the cross section of the molded body was observed at 50,000 times, and the average height of the protrusions was obtained by averaging the heights of the ten protrusions.

<Preparation of active energy ray-curable resin composition>
Dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.): 25 parts by mass
Pentaerythritol triacrylate (Daiichi Kogyo Seiyaku Co., Ltd.): 25 parts by mass,
Ethylene oxide modified dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd.): 25 parts by mass
Polyethylene glycol diacrylate (manufactured by Toagosei Co., Ltd.): 25 parts by mass,
1-hydroxycyclohexyl phenyl ketone (manufactured by BASF): 1 part by mass,
Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (manufactured by BASF): 0.5 mass,
Polyoxyethylene alkyl (12-15) ether phosphoric acid (manufactured by Nippon Chemical Sales Co., Ltd.): 0.1 parts by mass,
Were mixed to obtain an active energy ray-curable resin composition A.

"Example 1"
<Mold production>
An aluminum plate having a purity of 99.99% by mass and a thickness of 0.3 mm was cut into a size of 50 mm × 50 mm and electropolished in a perchloric acid / ethanol solution (volume ratio = 1/4). Used as material.
This aluminum substrate is immersed in a 0.5 mol / L phosphoric acid aqueous solution (liquid temperature 30 ° C.), anodized at a constant voltage of 40 V for 15 minutes (step (α)), and then 6 mass% phosphoric acid and Pretreatment was performed by immersing in an aqueous solution at 70 ° C. mixed with 1.8% by mass of chromic acid for 2 hours to remove the oxide film (step (β)).
Subsequently, the following steps (a) to (c) were performed.

Step (a):
As a phosphoric acid electrolyte, a 0.5 mol / L phosphoric acid aqueous solution was adjusted to 30 ° C. in a treatment tank, and the pretreated aluminum base material was immersed therein. Anodization was performed at a constant voltage of 40 V for 30 seconds to form an oxide film on the surface of the aluminum substrate.
Step (b):
After finishing step (a), leave the aluminum substrate immersed in the phosphoric acid aqueous solution in the same treatment tank as in step (a) for 8 minutes, and enlarge the pore diameter by etching. did.
Step (c):
After repeating step (a) and step (b) a total of five times, the aluminum substrate was pulled up from the phosphoric acid aqueous solution.

After the step (c), the aluminum substrate is washed with deionized water, and water on the surface is further removed by air blow to form a substantially conical shape with an average interval of 100 nm, an average depth of about 190 nm, and an average pore diameter of about 75 nm. A mold in which an oxide film having pores was formed was obtained. The results are shown in Table 1.
The mold thus obtained was subjected to mold release treatment by immersing it in an aqueous solution obtained by diluting TDP-8 (manufactured by Nikko Chemicals Co., Ltd.) to 0.1 mass% for 10 minutes and air drying overnight.

(Manufacture of molded products)
Filled with the active energy ray-curable resin composition A having the above composition between the mold subjected to the mold release treatment and the acrylic film (“Acryprene HBS010” manufactured by Mitsubishi Rayon Co., Ltd.) which is the molded body (transparent substrate). Then, the active energy ray-curable resin composition A was cured by irradiating ultraviolet rays with an integrated light quantity of 1000 mJ / cm ² with a high-pressure mercury lamp. Thereafter, the mold was peeled off to obtain a molded body (film) composed of a molded body main body and a cured product (cured resin layer) of the active energy ray-curable resin composition A.
A fine concavo-convex structure was formed on the surface of the molded body thus produced, and the average interval (pitch) between the protrusions was 100 nm, and the average height of the protrusions was about 180 nm.

"Example 2"
Pre-treatment anodic oxidation was performed using a 0.3 mol / L oxalic acid aqueous solution at a liquid temperature of 15 ° C. for 30 minutes at 40 V, and the concentration of the phosphoric acid aqueous solution in step (a) was set to 2.0 mol / L. A mold was manufactured in the same manner as in Example 1 except for the above.
In the obtained mold, an oxide film having substantially conical pores with an average interval of 100 nm, an average depth of about 200 nm, and an average pore diameter of about 90 nm was formed. The results are shown in Table 1.

"Example 3"
Pre-treatment anodic oxidation was performed using a 0.3 mol / L oxalic acid aqueous solution at a liquid temperature of 15 ° C. for 30 minutes at 40 V, and the concentration of the phosphoric acid aqueous solution in step (a) was 0.1 mol / L. A mold was manufactured in the same manner as in Example 1 except for the above.
In the obtained mold, an oxide film having substantially conical pores having an average interval of 100 nm, an average depth of about 90 nm, and an average pore diameter of about 60 nm was formed. The results are shown in Table 1.

"Comparative Example 1"
Pretreatment anodization was performed using a 0.3 mol / L oxalic acid aqueous solution at a liquid temperature of 15 ° C. for 30 minutes at 40 V, and the concentration of the phosphoric acid aqueous solution in step (a) was set to 0.03 mol / L. A mold was manufactured in the same manner as in Example 1 except for the above.
In the obtained mold, an oxide film having substantially conical pores having an average interval of 100 nm, an average depth of about 70 nm, and an average pore diameter of about 40 nm was formed. The results are shown in Table 1.

Example 4
The anodization of the pretreatment was performed using a 0.3 mol / L oxalic acid aqueous solution at a liquid temperature of 15 ° C. for 30 minutes at 40 V, and the temperature of the phosphoric acid aqueous solution in step (a) was 40 ° C. A mold was manufactured in the same manner as in Example 1.
In the obtained mold, an oxide film having substantially conical pores with an average interval of 100 nm, an average depth of about 210 nm, and an average pore diameter of about 80 nm was formed. The results are shown in Table 1.

"Example 5"
The anodization of the pretreatment was performed using a 0.3 mol / L oxalic acid aqueous solution at a liquid temperature of 15 ° C. for 30 minutes at 40 V, and the temperature of the phosphoric acid aqueous solution in step (a) was set to 20 ° C. A mold was manufactured in the same manner as in Example 1.
In the obtained mold, an oxide film having substantially conical pores with an average interval of 100 nm, an average depth of about 115 nm, and an average pore diameter of about 60 nm was formed. The results are shown in Table 1.

"Comparative Example 2"
The anodization of the pretreatment was performed using a 0.3 mol / L oxalic acid aqueous solution at a liquid temperature of 15 ° C. at 40 V for 30 minutes, and the temperature of the phosphoric acid aqueous solution in step (a) was set to 10 ° C. A mold was manufactured in the same manner as in Example 1.
In the obtained mold, an oxide film having substantially conical pores with an average interval of 100 nm, an average depth of about 45 nm, and an average pore diameter of about 40 nm was formed. The results are shown in Table 1.

"Example 6"
Pretreatment anodization was carried out using 0.8 mol / L oxalic acid aqueous solution at a liquid temperature of 15 ° C. and 60 V for 15 minutes, the constant voltage in step (a) was set to 60 V, and the anodization time was set to 20 seconds. A mold was produced in the same manner as in Example 1 except that the etching time in the step (b) was 5 minutes.
In the obtained mold, an oxide film having substantially conical pores having an average interval of 140 nm, an average depth of about 230 nm, and an average pore diameter of about 75 nm was formed. The results are shown in Table 1.

“Comparative Example 3”
A pre-treatment anodic oxidation was performed using 0.8 mol / L oxalic acid aqueous solution at a liquid temperature of 15 ° C. and 60 V for 15 minutes, and the temperature of the phosphoric acid aqueous solution in step (a) was set to 10 ° C. A mold was manufactured in the same manner as in Example 1 except that the voltage was 60 V, the anodic oxidation time was 20 seconds, and the etching time in step (b) was 5 minutes.
In the obtained mold, an oxide film having substantially conical pores having an average interval of 140 nm, an average depth of about 100 nm, and an average pore diameter of about 50 nm was formed. The results are shown in Table 1.

"Example 7"
Pretreatment anodization was carried out using 0.8 mol / L oxalic acid aqueous solution at a liquid temperature of 15 ° C. and 80 V for 15 minutes, the constant voltage in step (a) was set to 80 V, and the anodization time was set to 20 seconds. The etching time in the step (b) is 17 minutes, the step (a) and the step (b) are alternately repeated five times, and then the step (a) is finally performed to complete the step (c). Produced a mold in the same manner as in Example 1.
In the obtained mold, an oxide film having substantially conical pores having an average interval of 180 nm, an average depth of about 360 nm, and an average pore diameter of about 170 nm was formed. The results are shown in Table 1.

As is clear from Table 1, in steps (a) and (b), anodization and etching are performed using a phosphoric acid electrolyte solution in one processing tank, so that the taper shape is simple and has a small number of steps. It was possible to produce a mold having a small number of pores. Therefore, according to the present invention, it was shown that the mold can be manufactured easily and with high productivity.
In addition, an oxide film having pores having an average pore diameter of 60 nm or more was formed on the surfaces of the molds of Examples 1 to 7. Therefore, according to these molds, when the fine concavo-convex structure formed on the surface of the mold is transferred to the surface of the molded body, it is difficult for mold release to occur and the durability is excellent.
On the other hand, an oxide film having pores having an average pore diameter of 50 nm or less was formed on the surfaces of the molds of Comparative Examples 1 to 3. Therefore, the pore diameter is not sufficiently widened, and when the fine concavo-convex structure formed on the surface of the mold is transferred onto the surface of the molded body, defective release is likely to occur, and the durability is poor.

The mold obtained by the mold manufacturing method of the present invention is useful for economical and efficient mass production of antireflection articles, antifogging articles, antifouling articles, and water repellent articles.
Moreover, the molded object obtained by the manufacturing method of the molded object which has the fine concavo-convex structure on the surface of this invention is suitable as an antireflection article, an antifogging article, an antifouling article, and a water-repellent article.

DESCRIPTION OF SYMBOLS 10 Aluminum base material 12 Pore 14 Oxide film 16 Depression 18 Mold 20 Roll mold 22 Tank 24 Pneumatic cylinder 26 Nip roll 28 Active energy ray irradiation apparatus 30 Peeling roll 38 Active energy ray curable resin composition 40 Molded body 42 Film 44 Curing Resin layer 46 Protrusion

Claims (4)

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,
Having the following steps (a) and (b), the concentration of the following phosphoric acid electrolyte is 0.05 mol / L or more and 2.5 mol / L or less, and the liquid temperature is 18 ° C. or more and 45 ° C. or less, Mold manufacturing method.
Step (a): A step of immersing an aluminum base material in a phosphoric acid electrolyte and applying a voltage to anodize the surface of the aluminum base material to form an oxide film.
Step (b): After the step (a), the aluminum substrate is immersed in a phosphoric acid electrolyte solution and held without applying a voltage, and the oxide film formed in the step (a) Removing at least a portion.   The method for producing a mold according to claim 1, wherein in the step (a), a voltage applied to the aluminum substrate is 20 V or more and 150 V or less.   A mold is manufactured by the mold manufacturing method according to claim 1, and a fine concavo-convex structure comprising a plurality of pores formed on the surface of the mold is transferred to the surface of the molded body. The manufacturing method of the molded object to have. A molded body having a fine relief structure on the surface,
The fine concavo-convex structure is a reverse structure of the fine concavo-convex structure composed of a plurality of pores formed on the surface of the mold obtained by the mold manufacturing method according to claim 1 or 2 on the surface. Molded body having.

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