JP2016112869A - Producing method of transparent film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing method of a transparent film in which a fine uneven structure of a mold is accurately transcribed and an optical deformation defect is suppressed.SOLUTION: There is provided a producing method of a transparent film comprising a fine uneven structure consisting of a plurality of projecting parts of 400 nm or less of cycle on the surface, comprising (I) a step in which a surface of a specific aluminum substrate is processed with an acidic or alkali solution and then anodized so as to produce a mold in which a turned fine uneven structure consisting of a plurality of recessed parts is formed on the surface of the aluminum substrate on which there are dotted recesses having a circle equivalent diameter of 0.4 to 10.0 μm; (II) a step in which a resin composition having active energy ray hardening property is supplied on the surface side having the turned fine uneven structure of the mold, and active energy ray is irradiated for hardening to obtain the transparent film comprising the fine uneven structure on the surface; and (III) a step of separating the transparent film from the mold. Initial detachment force upon separation of the hardened product of the resin composition from the mold is 7 N/m or less.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a transparent film having a fine relief structure on the surface.

  In recent years, it has been known that an article having a fine concavo-convex structure with a period equal to or shorter than the wavelength of visible light on the surface exhibits an antireflection effect, a lotus effect, and the like. In particular, the concavo-convex structure called the moth-eye structure in which substantially conical convex portions are arranged is an effective anti-reflection means by continuously increasing the refractive index from the refractive index of air to the refractive index of the material of the article. It is known that

  As a method for forming a fine concavo-convex structure on the surface of an article, a mold having a fine concavo-convex structure formed on the surface (also referred to as a mold; hereinafter referred to as a mold) is used. A method of transferring the structure to the surface of the article, more specifically, a liquid active energy ray-curable resin composition is filled between a mold having a fine concavo-convex structure on the surface and a base material, and active energy rays are applied to this. A method of forming a cured resin layer in which a fine concavo-convex structure is transferred to the surface of a base material by irradiating and curing is drawing attention. In the above method, the quality of mold release from the surface of the article significantly affects the productivity of the article. That is, in the above method, when the mold is released from the surface of the cured resin layer, a resin residue may be generated on the surface of the mold, and a defect may be generated in the transferred fine uneven structure.

The following method has been proposed as a method for improving the mold releasability between the mold and the cured resin layer.
(1) A method of treating the surface of the mold on which the fine concavo-convex structure is formed with a release agent (external release agent) (see, for example, Patent Documents 1 and 2).
(2) A method of adding a release agent (internal release agent) to the material constituting the article.

However, the method (1) has the following problems.
(I) Since it is necessary to immerse the mold in a diluting solution of the mold releasing agent or to apply a diluting solution of the mold releasing agent to the mold and then to dry it, the mold releasing process is complicated and takes time.
(Ii) It may cause processing unevenness such as drying unevenness of the release agent.
(Iii) The mold release agent on the mold surface is likely to migrate to the surface of the article.
(Iv) The mold release agent does not spread sufficiently to every corner of the fine concavo-convex structure of the mold, and it is difficult to uniformly and sufficiently treat the region of the fine concavo-convex structure of the mold with the mold release agent. In addition, if foreign matter adheres to the region of the fine concavo-convex structure of the mold, it is difficult to treat the portion where the foreign matter is attached with a release agent. Therefore, a defect may occur in the transferred fine concavo-convex structure at a location where the release agent treatment on the surface of the mold is insufficient. In addition, in a place where the mold release agent treatment on the surface of the mold is insufficient, the cured resin is torn and fixed and remains, and a defective part is also generated in the fine uneven structure of the mold itself. When a mold is used, defects may occur repeatedly.

Further, the method (2) has the following problems.
(V) If the addition amount of the release agent is such that contamination by the release agent on the surface of the article does not cause a problem, the release property may be insufficient.
(Vi) On the other hand, when the release agent is added excessively, the surface of the article is contaminated with the release agent, resulting in poor appearance of the article.

In addition, the following method is proposed as a method of removing the foreign material adhering to the area | region of the fine grooving | roughness structure of a metal mold | die.
(3) A method of pressing the surface of the mold on which the fine concavo-convex structure is formed against an adhesive member having higher adhesion to the mold than the substrate (see, for example, Patent Document 3).

  However, since the method (3) uses an adhesive member having higher adhesion to the mold than the base material, the adhesion member may adhere to the mold (that is, a resin residue may be generated). . Moreover, even if the surface of the mold is treated with a release agent (external release agent) in advance in order to suppress the adhesion of the adhesive member (resin residue) to the mold, The problem that it is difficult to process remains, and the release agent is peeled off from the mold by the adhesive member together with the foreign matter. As described above, in the method (3), even if the foreign matter can be removed, the transferred fine concavo-convex structure is defective due to adhesion of the adhesive member to the mold or peeling of the release agent from the mold. May occur.

The following method has been proposed as a method for solving this problem.
(4) A specific active energy ray-curable resin composition for mold surface release treatment is supplied between the surface of the mold on which the fine concavo-convex structure is formed and the base material, and active energy rays are supplied thereto. After the mold is irradiated and cured, the mold surface is released from the mold surface by peeling the substrate together with the cured product of the active energy ray-curable resin composition for mold surface release treatment. Method (for example, refer to Patent Document 4).

JP 2007-326367 A Japanese Patent No. 4154595 JP 2009-266841 A Japanese Patent No. 4990414

  By the way, when manufacturing a mold having a fine concavo-convex structure on the surface, an aluminum substrate having a smooth surface is prepared by polishing the surface of the aluminum substrate in advance, and the surface-treated aluminum substrate is anodized. Thus, there is known a method for imparting a fine concavo-convex structure composed of a plurality of recesses (pores) to the surface of an aluminum substrate.

However, when an aluminum substrate is polished, depending on the material of the aluminum substrate used and the polishing conditions, a dent larger than the wavelength of visible light is formed on the surface of the obtained aluminum substrate. (Dents of about 4 to 10.0 μm) may be formed.
Therefore, for example, as shown in FIG. 4, dents 52 larger than the wavelength of visible light are scattered on the surface of the mold 50, and a fine concavo-convex structure is formed along the peripheral surface of the dents 52. In such a case, even if the mold surface is sufficiently released by the method described in Patent Document 4, there are the following problems. That is, in the surface of the mold 50, the portion where the recess 52 is not formed and the concave portion (pore) of the fine concavo-convex structure formed on the bottom 52 a of the recess 52 are formed so that the orientation of the pore is downward in the vertical direction. Has been. Therefore, the hardened | cured material of the active energy ray curable resin composition with which the recessed part of these parts was filled can be pulled out from a recessed part comparatively easily. However, the concave portion of the fine concavo-convex structure formed in the dent 52 is formed so that the direction of the pores approaches the direction parallel to the surface of the mold 50 from the downward in the vertical direction as it approaches the opening 52 b of the dent 52. The Therefore, the cured product of the active energy ray-curable resin composition filled in the concave portions of these portions is difficult to be pulled out from the concave portions. Therefore, in the case of the mold 50 in which the fine concavo-convex structure is formed along the peripheral surface of the recess 52, the peeling force tends to be locally increased. At a location where the peeling force is locally increased, a mold release failure occurs starting from the recess 52, and a resin residue is likely to occur.

  Once the resin residue is generated, the resin is more likely to deposit on the resin (that is, the resin residue is easily repeated). This resin deposition tends to occur more easily as the peel strength of the active energy ray-curable resin composition is higher. When an article is manufactured using such a mold, an optical distortion having a diameter of about several millimeters with the resin residue as a core may occur on the surface of the article even if the resin residue is in a granular form of about 100 μm. Such an optical distortion (hereinafter referred to as “optical distortion defect”) is easily visually recognized because the optical distortion defect has a diameter of several millimeters even when the resin residue is not visually recognized.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the manufacturing method of the transparent film by which the fine uneven structure of the metal mold | die was transcribe | transferred accurately, and the optical distortion defect was suppressed.

  As a result of intensive studies, the present inventors have found that when the initial peel force between the mold and the cured product of the active energy ray-curable resin composition is optimal, optical distortion defects due to the resin residue can be suppressed, and the present invention is It came to be completed.

That is, this invention has the following aspects.
[1] A method for producing a transparent film having a fine concavo-convex structure consisting of a plurality of convex portions having a period of 400 nm or less on the surface, wherein (I) the purity is 99.0 to 99.9%, and a standard electrode from aluminum After treating the surface of the aluminum substrate containing 0.05% or more of a substance having a low potential with an acidic or alkaline solution, the surface-treated aluminum substrate is anodized, and the equivalent circle diameter is 0.4 to 10. A step of manufacturing a mold in which an inverted structure of the fine concavo-convex structure formed of a plurality of concave portions is formed on the surface of an aluminum base material in which dents of 0 μm are scattered on the surface; (II) The active energy ray-curable resin composition is supplied to the surface having the inverted structure of the fine concavo-convex structure, and the active energy ray-curable resin composition is irradiated with the active energy ray to cure the active energy ray. Curing the fat composition to obtain a transparent film having the fine concavo-convex structure on the surface; and (III) separating the transparent film from the mold, and the active energy ray-curable resin. The manufacturing method of a transparent film whose initial peeling force by the 180 degree peeling test at the time of isolate | separating the hardened | cured material of a composition and the said metal mold | die is 7 N / m or less.
[2] The transparent film according to [1], wherein the active energy ray-curable resin composition includes a polymerizable compound and a release agent, and the release agent is a (poly) oxyalkylene alkyl phosphate compound. Production method.
[3] The transparent film according to [2], wherein the active energy ray-curable resin composition contains 0.2 to 1.5 parts by mass of the release agent with respect to 100 parts by mass of the polymerizable compound. Manufacturing method.
[4] Any one of [1] to [3], wherein the substance having a lower standard electrode potential than aluminum is at least one selected from the group consisting of magnesium, lithium, potassium, barium, calcium, sodium, and titanium. The manufacturing method of the transparent film as described in one.

  According to the method for producing a transparent film of the present invention, it is possible to produce a transparent film in which a fine concavo-convex structure of a mold is accurately transferred and optical distortion defects are suppressed.

It is sectional drawing which shows the manufacturing process of the metal mold | die which has an anodized alumina on the surface. It is a block diagram which shows an example of the manufacturing apparatus of the transparent film which has a fine uneven structure on the surface. It is sectional drawing which shows an example of the transparent film which has a fine uneven structure on the surface. It is sectional drawing which shows an example of the surface state of the metal mold | die obtained by anodizing the surface-treated aluminum base material.

Hereinafter, the present invention will be described in detail.
In the present specification, the “fine concavo-convex structure” means a structure in which the average interval (center-to-center distance) between adjacent convex portions or adjacent concave portions is not more than the visible light wavelength, that is, 400 nm or less.
The “active energy ray” means visible light, ultraviolet light, electron beam, plasma, heat ray (infrared ray or the like) and the like.
Further, “transparent” means transmitting at least light having a wavelength of 400 to 760 nm.
Further, the “pore” means a concave portion having a fine concavo-convex structure formed on an oxide film on the surface of an aluminum substrate.
The “interval between pores” means the distance between the centers of adjacent pores.
The “projection” refers to a convex portion having a fine concavo-convex structure formed on the surface of the transparent film.
“(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.
“(Poly) oxyalkylene alkyl phosphate compound” is a generic term for an oxyalkylene alkyl phosphate compound having one oxyalkylene group and a polyoxyalkylene alkyl phosphate compound having two or more oxyalkylene groups. is there.

"Transparent film manufacturing method"
The method for producing a transparent film of the present invention is a method for producing a transparent film having a fine concavo-convex structure having a plurality of convex portions with a period of 400 nm or less on the surface, and includes the following steps (I) to (III): .
Step (I): After treating the surface of an aluminum substrate containing 0.05% or more of a substance having a purity of 99.0 to 99.9% and a standard electrode potential lower than that of aluminum with an acidic or alkaline solution, The fine concavo-convex structure comprising a plurality of concave portions on the surface of the aluminum base material in which pits having an equivalent circle diameter of 0.4 to 10.0 μm are scattered on the surface by anodizing the surface-treated aluminum base material The process of manufacturing the metal mold | die with which the inversion structure of was formed.
Step (II): An active energy ray-curable resin composition is supplied to the surface of the mold having the inverted structure of the fine relief structure, and the active energy ray-curable resin composition is irradiated with active energy rays. Curing the active energy ray-curable resin composition to obtain a transparent film having the fine concavo-convex structure on the surface.
Step (III): A step of separating the transparent film and the mold.
Hereinafter, each step will be described in detail.

<Process (I)>
Step (I) is a step of manufacturing a mold having on its surface an inverted structure of the fine uneven structure (hereinafter also referred to as “inverted fine uneven structure”). Hereinafter, the surface of the mold having the inverted fine concavo-convex structure is also referred to as “mold surface”.
Examples of the shape of the mold include a roll shape, a belt shape, and a flat plate shape. Among these, a roll shape or a belt shape is preferable from the viewpoint that the inverted fine concavo-convex structure of the mold can be continuously transferred and the productivity can be further increased.

The mold is manufactured by forming an inverted fine concavo-convex structure on the surface of a mold base. Alternatively, the obtained mold may be used as a prototype, a replica mold may be produced from the prototype by electroforming or the like, and this may be used as the mold.
As the mold substrate, an aluminum substrate having a purity of 99.0 to 99.9% and containing 0.05% or more of a substance having a standard electrode potential lower than that of aluminum is used.
The purity of the aluminum substrate is 99.0% or more, preferably 99.5% or more, and more preferably 99.8% or more. If the purity of the aluminum substrate is low, when anodized, an uneven structure having a size that scatters visible light due to segregation of impurities may be formed, or the regularity of pores obtained by anodization may be reduced. is there.

Examples of the substance having a lower standard electrode potential than aluminum include magnesium, lithium, potassium, barium, calcium, sodium, and titanium. One of these may be contained alone in the aluminum substrate, or two or more thereof may be contained in the aluminum substrate. Among these, magnesium and titanium are preferable because the hardness of the aluminum substrate can be increased while the crystal grains of the aluminum substrate are refined.
The content of the substance having a standard electrode potential lower than that of aluminum is 0.05% or more, and preferably 0.10% or more. By containing 0.05% or more of a substance having a standard electrode potential lower than that of aluminum, the hardness of the aluminum substrate can be suitably maintained, and the aluminum substrate can be easily processed to have a desired shape. In addition, the crystal grains of aluminum can be reduced, and the level difference of the crystal grains can be reduced. When the crystal grain size is large, the step of the crystal grain becomes large, and when the transparent film and the mold are separated in the step (III) described later, a resin residue is generated at the step of the crystal grain, and the transferred fine uneven structure Defects occur, and the haze of the transparent film increases.
The upper limit of the content of the substance having a standard electrode potential lower than that of aluminum is 2.00% or less, preferably 1.00% or less, and more preferably 0.80% or less.

Examples of the shape of the aluminum substrate include a roll shape, a circular tube shape, a flat plate shape, and a sheet shape.
The aluminum base material may be formed by depositing aluminum on the surface of stainless steel or glass.

As a method for forming the inverted fine concavo-convex structure on the surface of the aluminum substrate, a method of forming anodized alumina having a plurality of pores (recesses) on the surface of the aluminum substrate is preferable. For example, the following step (a) The method which has-(g) is mentioned.
Step (a): A step of treating (polishing) the surface of the aluminum substrate using an acidic or alkaline solution as a polishing liquid.
Step (b): A step of forming an oxide film on the surface of the aluminum substrate by anodizing the aluminum substrate surface-treated in the step (a) in an electrolytic solution under a constant voltage.
Step (c): A step of removing all of the oxide film formed in step (b) and forming anodic oxidation pore generation points on the surface of the aluminum substrate.
Step (d): A step of anodizing the aluminum base material on which the pore generation point is formed in the step (c) again in the electrolytic solution to form an oxide film having pores at the pore generation point.
Step (e): A step of expanding the diameter of the pores formed in the step (d).
Step (f): Step of anodizing again in the electrolytic solution after step (e).
Step (g): A step of repeating steps (e) and (f) to obtain a mold in which anodized alumina having a plurality of pores is formed on the surface of an aluminum substrate.

(Process (a))
Step (a) is a step of treating (polishing) the surface of the aluminum substrate using an acidic or alkaline solution as a polishing liquid.
In addition, since the oil used when processing an aluminum base material in a defined shape may adhere, it is preferable to degrease before a process (a).

Known methods for polishing the surface of an aluminum substrate include mechanical polishing, chemical polishing, and electrochemical polishing.
Mechanical polishing is a method of mechanically scraping and polishing a metal surface. In general, mechanical polishing is performed by relatively moving the polishing body in a state where a polishing liquid having high hardness is interposed between the polishing body and the metal to be polished.
Chemical polishing is a method of smoothing an oxide film or substrate on a metal surface with an acidic or alkaline aqueous solution.
Electrochemical polishing is a method of dissolving and removing irregularities on the surface of aluminum by flowing DC electricity mainly in an electrolytic solution.

In step (a), since a higher level of smoothing is possible, the surface of the aluminum substrate can be polished using a method of performing mechanical polishing and chemical polishing (Chemical Mechanical Planarization: CMP method) at the same time. preferable. Further, the CMP method may be used in combination with one or more of mechanical polishing, chemical polishing, and electrochemical polishing described above.
Here, the CMP method is a method in which a polishing liquid is adsorbed to a polishing body such as cloth, paper, metal, and / or polishing is performed by supplying a polishing liquid between an object to be polished (aluminum base) and the polishing body. It is a polishing technique that smoothes the surface of the aluminum substrate with acid or alkali while scraping the surface of the aluminum substrate with the sharp part of the abrasive contained in the polishing liquid by rubbing the aluminum substrate with the body .

The polishing liquid is an acidic or alkaline solution containing an abrasive, a reducing agent and / or an oxidizing agent, and a solvent such as water.
Examples of the abrasive include colloidal alumina and colloidal silica. These may be used alone or in combination of two or more.
Examples of the reducing agent include hydrogen sulfide, sulfur dioxide, hydrogen peroxide, iron sulfide, sodium sulfite, sodium hydrogen sulfite, sodium thiosulfate, and sodium dithionite. These may be used alone or in combination of two or more.
Examples of the oxidizing agent include hydrogen peroxide, ozone, potassium permanganate, dilute nitric acid, concentrated nitric acid, and sodium hypochlorite. These may be used alone or in combination of two or more.

When the polishing liquid is an acidic solution, the pH is preferably 2 to 6. Examples of the pH adjuster (acid) for adjusting the pH of the polishing liquid include inorganic acids such as sulfuric acid, nitric acid and phosphoric acid; organic acids such as butyric acid, citric acid and acetic acid. These may be used alone or in combination of two or more.
When the polishing liquid is an alkaline solution, the pH is preferably 8-12. Examples of the pH adjuster (alkali) for adjusting the pH of the polishing liquid include sodium carbonate, sodium silicate, and sodium phosphate. These may be used alone or in combination of two or more.

  As the polishing liquid, an alkaline aqueous solution is preferable. Further, a plurality of polishing liquids having different pHs may be used in combination, for example, after polishing an aluminum substrate using an acidic polishing liquid and then performing a final polishing using an alkaline polishing liquid.

(Process (b))
The step (b) is a step of forming an oxide film on the surface of the aluminum substrate by anodizing the aluminum substrate surface-treated in the step (a) in an electrolytic solution under a constant voltage.
As shown in FIG. 1, when the aluminum substrate 10 is anodized, an oxide film 14 having pores 12 is formed.
Examples of the electrolytic solution include sulfuric acid, oxalic acid, and phosphoric acid.

When using oxalic acid as electrolyte:
The concentration of oxalic acid is preferably 0.7 M or less. When the concentration of oxalic acid exceeds 0.7M, the current value becomes too high, and the surface of the oxide film may become rough.
When the formation voltage is 30 to 60 V, anodized alumina having highly regular pores with an average interval of 100 nm can be obtained. Regardless of whether the formation voltage is higher or lower than this range, the regularity tends to decrease.
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:
The concentration of sulfuric acid is preferably 0.7M or less. If the concentration of sulfuric acid exceeds 0.7M, the current value may become too high to maintain a constant voltage.
When the formation voltage is 25 to 30 V, anodized alumina having highly regular pores with an average interval of 63 nm can be obtained. The regularity tends to decrease whether the formation voltage is higher or lower than this range.
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.

(Process (c))
Step (c) is a step of removing all of the oxide film formed in step (b) and forming anodic oxidation pore generation points on the surface of the aluminum substrate.
As shown in FIG. 1, the regularity of the pores can be improved by removing the oxide film 14 once and using it as the pore generation points 16 for anodic oxidation.
Examples of the method for removing the oxide film include a method in which aluminum is not dissolved but is dissolved in a solution that selectively dissolves the oxide film and removed. Examples of such a solution include a chromic acid / phosphoric acid mixed solution.

(Process (d))
Step (d) is a step in which the aluminum base material on which the pore generation point is formed in step (c) is anodized again in the electrolytic solution to form an oxide film having pores at the pore generation point.
As shown in FIG. 1, when the aluminum substrate 10 from which the oxide film has been removed is anodized again, an oxide film 14 having cylindrical pores 12 is formed.
Anodization may be performed under the same conditions as in step (b). Deeper pores can be obtained as the anodic oxidation time is lengthened.

(Process (e))
Step (e) is a step of expanding the diameter of the pores formed in step (d).
As shown in FIG. 1, when the process of expanding the diameter of the pores 12 (pore diameter expansion process) is performed, the diameter of the pores 12 is larger than that of the pores 12 formed in the step (d).
The pore diameter expansion treatment is a treatment for expanding the diameter of the pores obtained by anodic oxidation by immersing in a solution dissolving the oxide film. Examples of such a solution include a phosphoric acid aqueous solution of about 5% by mass.
The longer the pore diameter expansion processing time, the larger the pore diameter.

(Process (f))
Step (f) is a step of anodizing again in the electrolytic solution after step (e).
As shown in FIG. 1, when the aluminum substrate 10 is anodized again, cylindrical pores 12 having a small diameter and extending downward from the bottom of the cylindrical pores 12 are further formed.
Anodization may be performed under the same conditions as in step (b). Deeper pores can be obtained as the anodic oxidation time is lengthened.

(Process (g))
Step (g) is a step in which steps (e) and (f) are repeated to obtain a mold in which anodized alumina having a plurality of pores is formed on the surface of an aluminum substrate.
As shown in FIG. 1, when the pore diameter enlargement process in the step (e) and the anodization in the step (f) are repeated, the pores 12 have a shape in which the diameter continuously decreases from the opening in the depth direction. An oxide film 14 is formed, and a mold 18 having anodized alumina (aluminum porous oxide film (alumite)) on the surface of the aluminum substrate 10 is obtained. It is preferable that the last end is step (e).

  The total number of repetitions is preferably 3 times or more, and more preferably 5 times or more. When the number of repetitions is 2 times or less, the diameter of the pores decreases discontinuously, so that the effect of reducing the reflectance of the moth-eye structure formed using anodized alumina having such pores is insufficient.

  Examples of the shape of the pore 12 include a substantially conical shape, a pyramid shape, a cylindrical shape, and the like, and a cross-sectional area of the pore in a direction orthogonal to the depth direction such as a conical shape and a pyramid shape has a depth from the outermost surface. A shape that continuously decreases in the direction is preferred.

The average interval between the pores 12 is not more than the wavelength of visible light, that is, not more than 400 nm. The average interval between the pores 12 is preferably 20 nm or more.
The average interval between the pores 12 was measured by measuring the distance between adjacent pores 12 (distance from the center of the pore 12 to the center of the adjacent pore 12) by electron microscope observation, and these values were averaged. It is a thing.

The aspect ratio of the pores 12 (depth of pores / average interval between pores) is preferably 0.8 to 5.0, more preferably 1.2 to 4.0, and 1.5 to 3.0. Is particularly preferred.
The depth of the pore 12 is a value obtained by measuring the distance between the bottom of the pore 12 and the top of the convex portion existing between the pores 12 when observed with an electron microscope at a magnification of 30000 times. It is.

When the step (a) is performed, a recess having an equivalent circle diameter of 0.4 to 10.0 μm is formed on the surface of the aluminum base material. Therefore, the mold obtained through the steps (a) to (g) has a plurality of recesses (on the surface of the aluminum base material in which recesses having a circle equivalent diameter of 0.4 to 10.0 μm are scattered on the surface. Inverted fine concavo-convex structure consisting of pores) is formed.
Here, the equivalent circle diameter is a diameter of a circle having the same area as the obtained area by observing the surface of the mold with a scanning electron microscope to obtain the area of the recessed portion.

In addition, the manufacturing method of a metal mold | die is not limited to the method mentioned above, For example, it may replace with a process (c) and may perform the following process (c ').
Step (c ′): A step of removing a part of the oxide film formed in the step (b).

  As shown in FIG. 1, the pores 12 of the oxide film 14 formed in the step (b) vary in intervals. Therefore, in the step (c ′), the surface of the oxide film 14 is removed until there is no variation in the interval between the pores 12. The pores 12 exposed on the surface in the step (c ′) serve as pore generation points in the step (c).

Moreover, you may process the surface of the side which has the inversion fine concavo-convex structure of the obtained mold with an external mold release agent (mold release process). When the surface of the mold having the inverted fine concavo-convex structure is treated with an external mold release agent, the initial releasability can be obtained when transferring the reverse fine concavo-convex structure of the mold to the surface of the article (transparent film). It becomes good. Specifically, the initial peel force by a 180 ° peel test when separating the cured product of the active energy ray-curable resin composition described later and the mold is likely to be 7 N / m or less.
In addition, even when it is repeatedly transferred, the releasability is not easily lowered, so that a transparent film having a fine concavo-convex structure on the surface can be produced with high productivity.
Strictly speaking, the mold release treatment is performed by treating the surface of the reverse fine concavo-convex structure with a mold release agent on the mold having the reverse fine concavo-convex structure on the surface. It may be described that the “mold having on the surface” or “the surface of the mold” is processed.

As the external mold release agent, those having a functional group capable of forming a chemical bond with the anodized alumina of the aluminum base material are preferable. Specific examples include silicone resins, fluorine resins, fluorine compounds, and the like. A fluorine compound having a silyl group is particularly preferred.
Commercially available fluorine compounds having hydrolyzable silyl groups include fluoroalkylsilane, KBM-7803 (manufactured by Shin-Etsu Chemical Co., Ltd.), MRAF (manufactured by Asahi Glass Co., Ltd.), OPTOOL HD1100, HD2100 series (manufactured by Harves), OPTOOL AES4 , AES6 (manufactured by Daikin Industries), Novec EGC-1720 (manufactured by Sumitomo 3M), FS-2050 series (manufactured by Fluoro Technology), and the like.
Moreover, it has a fluorine-containing compound, a silicone compound, a phosphate ester compound, a compound having a long chain alkyl group, and a polyoxyalkylene group that can be used as an internal release agent contained in the active energy ray-curable resin composition described later. A compound, solid wax (polyethylene wax, amide wax, polytetrafluoroethylene powder, etc.) diluted with a solvent can also be used as an external mold release agent.

Examples of the mold release treatment method using an external mold release agent include the following method (α) or method (β), and the method (α) is particularly preferable because the surface of the mold can be treated with the external mold release agent without unevenness. preferable.
Method (α): A method in which a mold is immersed in a dilute solution of an external mold release agent.
Method (β): A method in which an external mold release agent or a diluted solution thereof is applied to the surface of the mold having the inverted fine concavo-convex structure.

As the method (α), a method having the following steps (h) to (m) is preferable.
Step (h): A step of washing the mold with water.
Step (i): After step (h), air is blown onto the mold to remove water droplets attached to the surface of the mold.
Step (j): A step of immersing the mold in a diluted solution in which a fluorine compound having a hydrolyzable silyl group is diluted with a fluorine-based solvent.
Step (k): A step of slowly lifting the immersed mold from the solution.
Step (l): A step of heating and humidifying the mold after the step (k) as necessary.
Step (m): A step of drying the mold.

(Process (h))
Step (h) is a step of washing the mold with water.
Because the chemicals used for forming the fine relief structure (phosphoric acid aqueous solution used for the pore size enlargement process, stripping solution used for the lithography method, etc.), impurities (dust, etc.) are attached to the mold. This is removed by washing with water.

(Process (i))
Step (i) is a step of removing water droplets attached to the surface of the mold by blowing air to the mold after the step (h).
If water droplets are attached to the surface of the mold, the diluted solution used in the step (j) is likely to be deteriorated, so that air is blown onto the mold to almost remove visible water droplets.

(Process (j))
Step (j) is a step of immersing the mold in a diluted solution obtained by diluting a fluorine compound having a hydrolyzable silyl group with a fluorine-based solvent.
Examples of the fluorine-based solvent for dilution include hydrofluoropolyether, perfluorohexane, perfluoromethylcyclohexane, perfluoro-1,3-dimethylcyclohexane, dichloropentafluoropropane, and the like.
The concentration of the fluorine compound having a hydrolyzable silyl group is preferably 0.01 to 0.50% by mass in the diluted solution (100% by mass).
The immersion time is preferably 1 to 30 minutes.
As for immersion temperature, 0-50 degreeC is preferable.

(Process (k))
Step (k) is a step of slowly lifting the immersed mold from the solution.
When pulling up the immersed mold from the solution, it is preferable to pull it up at a constant speed using an electric puller or the like to suppress swinging during pulling. This can reduce coating unevenness.
The pulling speed is preferably 1 to 10 mm / sec.

(Process (l))
Step (l) is a step of heating and humidifying the mold at a stage after step (k) as necessary.
By leaving the mold under heating and humidification, the hydrolyzable silyl group of the fluorine compound (release agent) is hydrolyzed to form a silanol group, and the reaction between the silanol group and the hydroxyl group on the mold surface is caused. It proceeds sufficiently and improves the fixability of the fluorine compound.
Examples of the humidifying method include a saturated salt method using a saturated salt aqueous solution, a method of heating and humidifying water, and a method of spraying heated steam directly onto a mold.
Step (l) may be performed in a constant temperature and humidity chamber.
The heating temperature is preferably 30 to 150 ° C.
The humidification condition is preferably a relative humidity of 60% or more.
The standing time is preferably 10 minutes to 7 days.

(Process (m))
Step (m) is a step of drying the mold.
In the step (m), the mold may be air-dried or forcibly heated and dried with a dryer or the like.
The drying temperature is preferably 30 to 150 ° C.
The drying time is preferably 5 to 300 minutes.

  In addition, it can confirm that the surface of the metal mold | die was processed with the external mold release agent by measuring the water contact angle of the metal mold | die surface. The water contact angle on the surface of the mold treated with the external release agent is preferably 60 ° or more, and more preferably 90 ° or more. When the water contact angle is 60 ° or more, the surface of the mold is sufficiently treated with an external mold release agent, and the mold release property is improved.

<Step (II), Step (III)>
Step (II) is a step of obtaining a transparent film having a fine concavo-convex structure on the surface using the mold obtained in step (I).
Step (III) is a step of separating the transparent film and the mold obtained in step (I).

  In step (II), an active energy ray-curable resin composition is supplied to the surface of the mold obtained in step (I) on the side having the inverted fine uneven structure, and the active energy ray-curable resin composition is supplied to the active energy ray-curable resin composition. The active energy ray-curable resin composition is cured by irradiating active energy rays to obtain a transparent film having the fine uneven structure on the surface. At this time, the active energy ray-curable resin composition is cured in a state sandwiched between the mold and the base material, and a cured resin layer to which the inverted fine uneven structure of the mold is transferred is formed on the surface of the base material. It is preferable to do.

Examples of the shape of the substrate include films, sheets, injection molded products, press molded products, extruded molded products, cast molded products, and the like.
As a base material, since active energy ray irradiation is performed over a base material, the thing of a material with high light transmittance is preferable. Examples of highly light transmissive materials include polycarbonate, polystyrene resin, polyester, polyurethane, acrylic resin, polyether sulfone, polysulfone, polyether ketone, cellulose resin (triacetyl cellulose, etc.), polyolefin, and alicyclic. Examples include polyolefin and glass.
The surface of the substrate may be subjected to coating, corona treatment, etc. for the purpose of improving properties such as adhesion, antistatic properties, scratch resistance, and weather resistance.

Process (II) and process (III) are performed as follows, for example using the manufacturing apparatus shown in FIG.
From the tank 22 between a roll-shaped mold 20 having an inverted fine concavo-convex structure (not shown) on the surface and a strip-shaped base material (base film) 42 that moves along the surface of the roll-shaped mold 20. An active energy ray-curable resin composition 24 is supplied.

  The base film 42 and the active energy ray curable resin composition 24 are nipped between the roll-shaped mold 20 and the nip roll 28 whose nip pressure is adjusted by the pneumatic cylinder 26, and the active energy ray curable resin composition is niped. 24 is uniformly distributed between the base film 42 and the roll-shaped mold 20, and at the same time, is filled in the recesses (pores) of the inverted fine concavo-convex structure of the roll-shaped mold 20.

The active energy ray curable resin composition 24 is irradiated from the active energy ray irradiation device 30 installed below the roll-shaped mold 20 through the base film 42 to the active energy ray curable resin composition 24. Is cured to form a cured resin layer 44 to which the inverted fine concavo-convex structure on the surface of the roll-shaped mold 20 is transferred.
By peeling the base film 42 having the cured resin layer 44 formed on the surface thereof from the roll-shaped mold 20 by the peeling roll 32, a transparent film 40 as shown in FIG.

(Active energy ray-curable resin composition)
The active energy ray-curable resin composition includes a polymerizable compound and a polymerization initiator.
The active energy ray-curable resin composition has an initial peel force of 7 N / m or less in a 180 ° peel test when separating the cured product of the active energy ray-curable resin composition and the mold. It is preferable to use a simple resin composition.
As described above, when the metal substrate is polished prior to the anodic oxidation of the aluminum substrate, the surface has a dent larger than the wavelength of visible light (specifically, the equivalent circle diameter is 0.4 to 10.0 μm). ), And an inverted fine concavo-convex structure is also formed on this dent (see FIG. 4), and the peeling force tends to increase locally. Therefore, when an article such as a transparent film is manufactured using such a mold, a resin residue is generated starting from the dent, and the resin is deposited on the remaining resin portion by repeating the transfer, and an optical distortion defect occurs. Cause.
However, if the initial peeling force is 7 N / m or less, the mold release property between the transparent film (specifically, the cured resin layer) and the mold is increased, so that the recess is formed on the surface of the mold. Moreover, the resin residue to a metal mold | die can be suppressed. Therefore, a transparent film in which the inverted fine concavo-convex structure of the mold is accurately transferred and optical distortion defects are suppressed can be obtained.

  In addition, when the shape of the mold is a roll shape or a circular tube shape, it may be difficult to perform a 180 ° peel test. In such a case, except for the shape, the same aluminum base material as that of the roll-shaped or cylindrical mold is used, and a flat plate-shaped or sheet-shaped mold is manufactured under the same conditions. A 180 ° peel test is performed to determine an initial peel force, which is regarded as an initial peel force between a roll-shaped or circular tubular mold and a cured product of the active energy ray-curable resin composition.

The initial peeling force can be adjusted by adjusting the composition of the active energy ray-curable resin composition. For example, the initial release force can be adjusted by blending a release agent (internal release agent) with the active energy ray-curable resin composition and adjusting the amount of the internal release agent. The initial peeling force tends to decrease as the amount of the internal release agent increases.
The initial peeling force can also be adjusted by releasing the surface of the mold with an external release agent.
Hereinafter, each component contained in the active energy ray-curable resin composition will be described. Of the components contained in the active energy ray-curable resin composition, at least one is preferably an acrylic component.

<< polymerizable compound >>
Examples of the polymerizable 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 include 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 derivatives such as acrylate, hydroxypropyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate; (meth) acrylic acid; (meth) acrylonitrile; styrene, α -Styrene derivatives such as methylstyrene; (meth) acrylamide derivatives such as (meth) acrylamide, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide and the like. These may be used alone or in combination of two or more.

  Polyfunctional monomers include ethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, isocyanuric acid ethylene oxide modified di (meth) acrylate, triethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate , Neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,5-pentanediol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, polybutylene glycol di (Meth) acrylate, 2,2-bis (4- (meth) acryloxypolyethoxyphenyl) propane, 2,2-bis (4- (meth) acryloxyethoxyphenyl) propane, 2,2-bis (4- (3- ( Ta) acryloxy-2-hydroxypropoxy) phenyl) propane, 1,2-bis (3- (meth) acryloxy-2-hydroxypropoxy) ethane, 1,4-bis (3- (meth) acryloxy-2-hydroxypropoxy) ) Butane, dimethylol tricyclodecane di (meth) acrylate, ethylene oxide adduct di (meth) acrylate of bisphenol A, propylene oxide adduct di (meth) acrylate of bisphenol A, neopentyl glycol di (meth) hydroxypivalate Bifunctional monomers such as acrylate, divinylbenzene, and methylenebisacrylamide; pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethylene oxide Trifunctional monomers such as tri (meth) acrylate, trimethylolpropane propylene oxide modified triacrylate, trimethylolpropane ethylene oxide modified triacrylate, isocyanuric acid ethylene oxide modified tri (meth) acrylate; succinic acid / trimethylolethane / acrylic acid Condensation reaction mixture, dipentaerythrole hexa (meth) acrylate, dipentaerystol penta (meth) acrylate, ditrimethylolpropane tetraacrylate, tetramethylolmethane tetra (meth) acrylate and other tetrafunctional or higher monomers; bifunctional or higher functional Examples thereof include urethane acrylate and bifunctional or higher functional polyester acrylate. 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 include unsaturated polyesters such as a condensate of unsaturated dicarboxylic acid and polyhydric alcohol; polyester (meth) acrylate, polyether (meth) acrylate, polyol (meth) acrylate, epoxy (meth) Examples thereof include acrylates, urethane (meth) acrylates, cationic polymerization type epoxy compounds, homopolymers of the above-described monomers having a radical polymerizable bond in the side chain, and copolymerized polymers.

<< Polymerization initiator >>
As the polymerization initiator, a compound that generates radicals or cations when irradiated with active energy rays is used. From the viewpoint of apparatus cost and productivity, a photopolymerization initiator using ultraviolet rays as an active energy ray is preferable.

  When using a photocuring reaction, examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl, benzophenone, p-methoxybenzophenone, and 2,2-diethoxyacetophenone. , Α, α-dimethoxy-α-phenylacetophenone, methylphenylglyoxylate, ethylphenylglyoxylate, 4,4′-bis (dimethylamino) benzophenone, 2-hydroxy-2-methyl-1-phenylpropane-1 Carbonyl compounds such as -one; sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoyldi Such as butoxy phosphine oxide. These may be used alone or in combination of two or more.

  When using an electron beam curing reaction, examples of the polymerization initiator include benzophenone, 4,4-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophenone, methyl orthobenzoyl benzoate, 4-phenylbenzophenone, and t-butyl. Thioxanthones such as anthraquinone, 2-ethylanthraquinone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone; diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl Ketal, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholino Acetyl) -butanone and the like; benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl)- Acylphosphine oxides such as 2,4,4-trimethylpentylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide; methylbenzoylformate, 1,7-bisacridinylheptane, 9-phenyl Examples include acridine. These may be used alone or in combination of two or more.

  When utilizing a thermosetting reaction, examples of the thermal polymerization initiator include methyl ethyl ketone peroxide, benzoyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxy octoate, organic peroxides such as t-butylperoxybenzoate and lauroyl peroxide; azo compounds such as azobisisobutyronitrile; N, N-dimethylaniline, N, N-dimethyl-p- Examples thereof include a redox polymerization initiator combined with an amine such as toluidine. These may be used alone or in combination of two or more.

  The content of the polymerization initiator in the active energy ray-curable resin composition is preferably 0.1 to 10.0 parts by mass with respect to 100 parts by mass of the polymerizable compound. If content of a polymerization initiator is 0.1 mass part or more, superposition | polymerization will fully advance. On the other hand, if content of a polymerization initiator is 10.0 mass parts or less, the hardened | cured material (cured resin layer) of an active energy ray-curable resin composition will be hard to color, and the fall of mechanical strength can also be suppressed.

<< Internal release agent >>
When the active energy ray-curable resin composition contains an internal release agent, continuous transferability can be improved. Moreover, the fall of the adhesiveness with respect to the base material of a cured resin layer is suppressed, As a result, the resin residue (mold release defect) to a metal mold | die and peeling of the cured resin layer from a base material can be suppressed more. In addition, since the releasability from the mold is further enhanced, the resin residue (mold release failure) on the mold can be further suppressed.

The internal mold release agent improves the mold releasability between the cured resin layer and the mold surface, and is compatible with components other than the internal mold release agent contained in the active energy ray-curable resin composition. For example, the composition of the internal release agent is not particularly limited.
Examples of the internal release agent include (poly) oxyalkylene alkyl phosphate ester compounds, phosphate ester compounds other than (poly) oxyalkylene alkyl phosphate ester compounds, fluorine-containing compounds, silicone compounds, and long-chain alkyl groups. And a compound having a polyoxyalkylene group, solid wax (polyalkylene wax, amide wax, polytetrafluoroethylene powder, etc.), and the like. These may be used alone or in combination of two or more. Among these, (poly) oxyalkylene alkyl phosphate ester compounds are preferable.

  When the active energy ray-curable resin composition contains a (poly) oxyalkylene alkyl phosphate ester compound as an internal release agent, the release property between the cured resin layer that is the cured product and the mold is better. Become. Further, since the load at the time of mold release is extremely low, the fine concavo-convex structure is hardly damaged, and as a result, the inverted fine concavo-convex structure of the mold can be transferred efficiently and accurately. In particular, if the mold surface is subjected to a mold release treatment using a (poly) oxyalkylene alkyl phosphate compound as an external mold release agent, the mold releasability between the cured resin layer and the mold is further enhanced.

The (poly) oxyalkylene alkyl phosphate compound is preferably a compound represented by the following formula (1) from the viewpoint of releasability.
^{_{(HO) 3-n (O}} =) P [-O- (R 2 O) m -R 1] n ··· (1)
In the formula (1), ^{R 1} is an alkyl group, ^{R 2} is an alkylene group, m is an integer of 1 to 20, n is an integer of 1-3.

The R ^1, preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 3 to 18 carbon atoms.
R ² is preferably an alkylene group having 1 to 4 carbon atoms, and more preferably an alkylene group having 2 to 3 carbon atoms.
m is preferably an integer of 1 to 10.

  The (poly) oxyalkylene alkyl phosphate compound may be a monoester (n = 1), a diester (n = 2), or a triester (n = 3). In the case of a diester or triester, a plurality of (poly) oxyalkylene alkyl groups in one molecule may be different from each other.

Examples of commercially available (poly) oxyalkylene alkyl phosphate compound include the following.
Johoku Chemical Co., Ltd .: JP-506H,
Accelerator: Mold with INT-1856,
Nikko Chemicals: TDP-10, TDP-8, TDP-6, TDP-2, DDP-10, DDP-8, DDP-6, DDP-4, DDP-2, TLP-4, TCP-5, DLP -10.
The (poly) oxyalkylene alkyl phosphate ester compound may be used alone or in combination of two or more.

  The mold of the active energy ray-curable resin composition having a fine concavo-convex structure with a content of (poly) oxyalkylene alkyl phosphate ester compound of 100 parts by mass of the polymerizable compound and having a wavelength of normal visible light or less. If it is, 0.01-1.00 mass part is preferable. However, dents larger than the wavelength of visible light (specifically, dents having an equivalent circle diameter of 0.4 to 10.0 μm) are scattered on the surface of the mold having a fine concavo-convex structure, and the inverted fine concavo-convex is formed on the surface. When manufacturing a transparent film using the metal mold | die in which the structure is formed, 0.2-1.5 mass parts is preferable, 0.2-1.0 mass part is more preferable, 0.3-0 More preferably, 5 parts by mass.

  When the content of the (poly) oxyalkylene alkyl phosphate compound is 0.2 parts by mass or more, the peeling force between the mold and the cured product (cured resin layer) of the active energy ray-curable resin composition is sufficient. (Specifically, the initial peel force tends to be 7 N / m or less), and even if the dent is formed on the surface of the mold, the resin residue on the mold hardly occurs. Therefore, optical distortion defects and transfer omissions are less likely to occur in the transferred fine concavo-convex structure. Moreover, the fall of the adhesiveness with respect to the base material of a cured resin layer is suppressed, As a result, the resin residue to a metal mold | die is suppressed.

  Further, when the content of the (poly) oxyalkylene alkyl phosphate compound is 0.2 parts by mass or more, a sufficient amount of the (poly) oxyalkylene alkyl phosphate compound can be transferred to the surface of the mold. In addition, the releasability from the mold is sufficient, and the resin residue on the mold is suppressed. Furthermore, not only the mold releasability from the mold, but also the releasability for the active energy ray-curable resin composition is improved. Further, it is possible to prevent the resin from being further deposited (the resin residue is repeated). Therefore, a transparent film in which optical distortion defects are suppressed is obtained.

  Moreover, if the content of the (poly) oxyalkylene alkyl phosphate compound is in the range of 0.2 to 1.5 parts by mass, the alignment of the protrusions generated when the surface of the transparent film on the fine uneven structure side is wiped with water. Can be suppressed. This is because the surface of the fine concavo-convex structure of the transparent film can also exhibit sufficient releasability as the cured resin layer has sufficient releasability with respect to the mold. Therefore, when the surface of the transparent film on the fine concavo-convex structure side is wiped with water, or when a constant temperature and humidity durability test (for example, 85 ° C., 85 RH%, 200 hours, etc.) is performed, the unity of protrusions of the fine concavo-convex structure is suppressed. It is considered possible. In the active energy ray-curable resin composition having the same composition other than the (poly) oxyalkylene alkyl phosphate compound, although depending on the composition of the active energy ray-curable resin composition, the shape and period of the protrusions, etc., (poly) The composition containing 0.2 to 1.5 parts by mass of the oxyalkylene alkyl phosphate compound is compared with the composition not containing 0.2 to 1.5 parts by mass of the (poly) oxyalkylene alkyl phosphate compound, It is possible to reduce the protrusion unity by about 10%.

  The active energy ray-curable resin composition is also referred to as an internal mold release agent other than the (poly) oxyalkylene alkyl phosphate compound (hereinafter referred to as “other internal mold release agent”) for the purpose of further improving mold release properties. ) May be included. Other internal mold release agents include those described above.

<< Other ingredients >>
The active energy ray-curable resin composition is made of a non-reactive polymer, an active energy ray sol-gel reactive composition, an antistatic agent, an additive such as a fluorine compound for improving antifouling properties, and fine particles as necessary. A small amount of a solvent may be contained.

Examples of non-reactive polymers include acrylic resins, styrene resins, polyurethanes, cellulose resins, polyvinyl butyral, polyesters, thermoplastic elastomers, and the like.
Examples of the active energy ray sol-gel reactive composition include alkoxysilane compounds and alkyl silicate compounds.

Examples of the alkoxysilane compound include tetramethoxysilane, tetra-i-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-s-butoxysilane, tetra-t-butoxysilane, methyltriethoxysilane, Examples include methyltripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, trimethylmethoxysilane, trimethylpropoxysilane, and trimethylbutoxysilane.
Examples of the alkyl silicate compound include methyl silicate, ethyl silicate, isopropyl silicate, n-propyl silicate, n-butyl silicate, n-pentyl silicate, acetyl silicate and the like.

  The cured product (cured resin layer) of the active energy ray-curable resin composition may be hydrophobic or hydrophilic. By changing the cured product of the active energy ray-curable resin composition to hydrophobic or hydrophilic, performance (for example, water resistance and fingerprint wiping property) can be imparted to the transparent film as necessary.

Hydrophobic material:
When the transparent film is required to have water repellency (specifically, the water contact angle of the surface of the fine uneven structure of the cured resin layer is 90 ° or more), active energy ray curing that can form a hydrophobic material As the conductive resin composition, it is preferable to use a composition containing a fluorine-containing compound or a silicone compound.

  Examples of the fluorine-containing compound include a fluorine-containing monomer, a fluorine-containing silane coupling agent, a fluorine-containing surfactant, and a fluorine-containing polymer.

Examples of the fluorine-containing monomer include a fluoroalkyl group-substituted vinyl monomer and a fluoroalkyl group-substituted ring-opening polymerizable monomer.
Examples of the fluoroalkyl group-substituted vinyl monomer include fluoroalkyl group-substituted (meth) acrylates, fluoroalkyl group-substituted (meth) acrylamides, fluoroalkyl group-substituted vinyl ethers, and fluoroalkyl group-substituted styrenes.

  Examples of the fluoroalkyl group-substituted ring-opening polymerizable monomer include fluoroalkyl group-substituted epoxy compounds, fluoroalkyl group-substituted oxetane compounds, and fluoroalkyl group-substituted oxazoline compounds.

  Fluorine-containing silane coupling agents include 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriacetoxysilane, dimethyl-3,3,3-trifluoropropylmethoxysilane, Examples include decafluoro-1,1,2,2-tetrahydrooctyltriethoxysilane.

  Examples of the fluorine-containing surfactant include a fluoroalkyl group-containing anionic surfactant and a fluoroalkyl group-containing cationic surfactant.

  Fluorine-containing polymers include polymers of fluoroalkyl group-containing monomers, copolymers of fluoroalkyl group-containing monomers and poly (oxyalkylene) group-containing monomers, and copolymers of fluoroalkyl group-containing monomers and crosslinking reactive group-containing monomers. A polymer etc. are mentioned. The fluorine-containing polymer may be a copolymer with another copolymerizable monomer.

Examples of the silicone compound include (meth) acrylic acid-modified silicone, silicone resin, silicone silane coupling agent and the like.
Examples of the (meth) acrylic acid-modified silicone include silicone (di) (meth) acrylate, and examples include silicone diacrylates “x-22-164” and “x-22-1602” manufactured by Shin-Etsu Chemical Co., Ltd. Preferably used.

Hydrophilic material:
When the transparent film is required to have hydrophilicity (specifically, the water contact angle of the surface of the fine uneven structure of the cured resin layer is 25 ° or less), active energy ray curing that can form a hydrophilic material As the conductive resin composition, it is preferable to use a composition containing at least a hydrophilic monomer. Further, from the viewpoint of imparting scratch resistance and water resistance, an active energy ray-curable resin composition containing a cross-linkable polyfunctional monomer is more preferable. In addition, the same (namely, hydrophilic polyfunctional monomer) may be sufficient as the polyfunctional monomer which can be bridge | crosslinked with a hydrophilic monomer. Furthermore, the active energy ray-curable resin composition may contain other monomers.

  The active energy ray-curable resin composition capable of forming a hydrophilic material includes a tetrafunctional or higher polyfunctional (meth) acrylate, a bifunctional or higher hydrophilic (meth) acrylate, and a monofunctional monomer as necessary. More preferably, the composition is used.

Examples of the tetrafunctional or higher polyfunctional (meth) acrylate include ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol ethoxytetra (meth) acrylate, dipentaerythritol hydroxypenta (meth) acrylate, di Pentaerythritol hexa (meth) acrylate, succinic acid / trimethylolethane / acrylic acid molar mixture 1: 2: 4 condensation reaction mixture, urethane acrylates (manufactured by Daicel-Cytec: EBECRYL220, EBECRYL1290K, EBECRYL1290K, EBECRYL5129, EBECRYL8210, EBECRYL 8301, KRM 8200), polyether acrylates (manufactured by Daicel-Cytec: EBEC) YL81), modified epoxy acrylates (manufactured by Daicel-Cytec: EBECRYL3416), polyester acrylates (manufactured by Daicel-Cytech: EBECRYL450, EBECRYL657, EBECRYL800, EBECRYL810, EBECRYL8111, EBECRYL81L, EBECRYL81L It is done. These may be used alone or in combination of two or more.
The polyfunctional (meth) acrylate having 4 or more functional groups is more preferably a polyfunctional (meth) acrylate having 5 or more functional groups.

  The content of the tetrafunctional or higher polyfunctional (meth) acrylate is preferably 10 to 50% by mass in 100% by mass of the polymerizable compound, and more preferably 20 to 50% by mass from the viewpoint of water resistance and chemical resistance. 30-50 mass% is especially preferable. When the content of the tetrafunctional or higher polyfunctional (meth) acrylate is 10% by mass or more, the elastic modulus is increased and the scratch resistance is improved. If the ratio of the tetrafunctional or higher polyfunctional (meth) acrylate is 50% by mass or less, small cracks are hardly formed on the surface, and the appearance is hardly deteriorated.

Long-chains such as Aronix M-240, Aronix M260 (manufactured by Toagosei Co., Ltd.), NK ester AT-20E, NK ester ATM-35E (manufactured by Shin-Nakamura Chemical Co., Ltd.) Examples thereof include polyfunctional acrylates having polyethylene glycol and polyethylene glycol dimethacrylate. These may be used alone or in combination of two or more.
In the polyethylene glycol dimethacrylate, the total of the average repeating units of the polyethylene glycol chain present in one molecule is preferably 6 to 40, more preferably 9 to 30, and particularly preferably 12 to 20. If the average repeating unit of the polyethylene glycol chain is 6 or more, the hydrophilicity is sufficient and the antifouling property is improved. When the average repeating unit of the polyethylene glycol chain is 40 or less, the compatibility with a polyfunctional (meth) acrylate having 4 or more functionalities is improved, and the active energy ray-curable resin composition is hardly separated.

  30-100 mass% is preferable in 100 mass% of polymeric compounds, and, as for content of bifunctional or more hydrophilic (meth) acrylate, 40-70 mass% is more preferable. If content of bifunctional or more hydrophilic (meth) acrylate is 30 mass% or more, hydrophilicity will become sufficient and antifouling property will improve. When the content of the bifunctional or higher hydrophilic (meth) acrylate is 80% by mass or less, the elastic modulus is increased and the scratch resistance is improved.

As the monofunctional monomer, a hydrophilic monofunctional monomer is preferable.
Examples of hydrophilic monofunctional monomers include monofunctional (meth) acrylates and hydroxyalkyl (meth) acrylates having a polyethylene glycol chain in the ester group such as M-20G, M-90G, and M-230G (manufactured by Shin-Nakamura Chemical Co., Ltd.). And cationic monomers such as monofunctional (meth) acrylates having a hydroxyl group in the ester group, monofunctional acrylamides, methacrylamide propyltrimethylammonium methyl sulfate, methacryloyloxyethyltrimethylammonium methyl sulfate, and the like.
Further, as the monofunctional monomer, a viscosity modifier such as acryloylmorpholine or vinylpyrrolidone, an adhesion improver such as acryloyl isocyanate for improving the adhesion to the article body, or the like may be used.

  The content of the monofunctional monomer is preferably 0 to 20% by mass and more preferably 5 to 15% by mass in 100% by mass of the polymerizable compound. By using a monofunctional monomer, the adhesion between the substrate and the cured resin layer is improved. If the content of the monofunctional monomer is 20% by mass or less, antifouling property or scratch resistance can be obtained without a shortage of polyfunctional (meth) acrylate having 4 or more functional groups or hydrophilic (meth) acrylate having 2 or more functional groups. Fully express.

  The monofunctional monomer may be blended in an active energy ray-curable resin composition as a low-polymerization polymer obtained by (co) polymerizing one or two or more of 0 to 35% by mass in 100% by mass of the polymerizable compound. Good. As the polymer having a low degree of polymerization, 40/40 of monofunctional (meth) acrylates having a polyethylene glycol chain in an ester group such as M-230G (manufactured by Shin-Nakamura Chemical Co., Ltd.) and methacrylamide propyltrimethylammonium methyl sulfate 60 copolymerization oligomer (manufactured by MRC Unitech Co., Ltd., MG polymer).

<< Viscosity >>
The viscosity of the active energy ray curable resin composition with a rotary B-type viscometer at 25 ° C. is that the active energy ray curable resin composition can be sufficiently supplied to the details of the inverted fine uneven structure of the mold. It is preferably 10 Pa · s or less, more preferably 5 Pa · s or less, and particularly preferably 2 Pa · s or less. If the viscosity at 25 ° C. of the active energy ray-curable resin composition is 10 Pa · s or less, the followability of the active energy ray-curable resin composition to the inversion fine uneven structure of the mold becomes good, and the inversion fine uneven structure. Can be transferred more accurately. Moreover, when supplying to the surface of a metal mold | die, you may heat beforehand and may reduce a viscosity.

(Active energy rays)
Examples of active energy rays include visible light, ultraviolet rays, electron beams, plasma, and heat rays (infrared rays and the like). Among these, ultraviolet rays are preferable.
Examples of the lamp that irradiates ultraviolet rays include a chemical lamp, a high-pressure mercury lamp, a metal halide lamp, an electrodeless UV lamp (manufactured by Fusion UV Systems), and a UV-LED lamp. Moreover, you may use together hardening by a heat | fever.

What is necessary is just to determine the irradiation amount of an ultraviolet-ray according to the absorption wavelength and content of a polymerization initiator contained in an active energy ray curable resin composition. Normally, the integrated quantity of ultraviolet light is 100~10000mJ / cm ^2, preferably ^{100~8000mJ / cm 2, 400~6000mJ / cm} 2 is more preferable. If the integrated light quantity of ultraviolet rays is 100 mJ / cm ² or more, the active energy ray-curable resin composition can be sufficiently cured. If the integrated light quantity of ultraviolet rays is 10,000 mJ / cm ² or less, deterioration of the substrate can be suppressed.
Moreover, it is preferable to suppress the irradiation intensity of ultraviolet rays to an output that does not cause deterioration of the base material.

<Effect>
Usually, when the adhesive force between the mold and the active energy ray-curable resin composition is stronger than the adhesive force between the base material and the active energy ray-curable resin composition, the active energy ray-curable resin composition is cured. After that, when the transparent film and the mold are separated, the active energy ray-curable resin composition may locally adhere and remain on the surface of the mold.
As described above, when the metal substrate is polished prior to the anodic oxidation of the aluminum substrate, the surface has a dent larger than the wavelength of visible light (specifically, the equivalent circle diameter is 0.4 to 10.0 μm). ), And an inverted fine concavo-convex structure is also formed on this dent (see FIG. 4), and the peeling force tends to increase locally. Therefore, when an article such as a transparent film is manufactured using such a mold, a resin residue is generated starting from the dent, and the resin is deposited on the remaining resin portion by repeating the transfer, and an optical distortion defect occurs. Cause.
A transparent film having a fine uneven structure with a period of less than or equal to the wavelength of visible light on the surface is very excellent in antireflection performance, so that an optical distortion defect or the like due to such a resin residue is easily visually recognized.

However, in the method for producing a transparent film of the present invention, the initial peel force by a 180 ° peel test when separating the cured product (cured resin layer) of the active energy ray-curable resin composition and the mold is 7 N / m. Because of the following, the releasability between the transparent film (specifically, the cured resin layer) and the mold is improved, and even if the dent is formed on the surface of the mold, the resin remains on the mold and the transfer is lost. Can be suppressed. Moreover, even if the resin residue occurs locally, it is possible to suppress the resin from further depositing on the resin where the resin remains (the resin residue is repeated).
Therefore, according to the method for producing a transparent film of the present invention, it is possible to obtain a transparent film in which the inverted fine concavo-convex structure of the mold is accurately transferred and optical distortion defects are suppressed.

"Transparent film"
FIG. 3 is a cross-sectional view showing an example of the transparent film 40 obtained by the method for producing a transparent film of the present invention.
In the transparent film 40 obtained by the present invention, a cured resin layer 44 having a fine concavo-convex structure formed by transferring the inverted fine concavo-convex structure of a mold in a relationship between a key and a keyhole is formed on the surface of a base material (base film) 42. It has been done.
As the base material 42, the base material illustrated previously in description of process (II) is mentioned.

The cured resin layer 44 is a film made of a cured product of the active energy ray-curable resin composition described above, and has a fine uneven structure on the surface.
The fine concavo-convex structure on the surface of the transparent film 40 when an anodized alumina mold is used is formed by transferring the inverted fine concavo-convex structure on the surface of the anodized alumina, and the active energy ray-curable resin composition It has the some convex part 46 which consists of hardened | cured material of a thing.

  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 average interval between the convex portions is not more than the wavelength of visible light, that is, not more than 400 nm. When the protrusions are formed using a mold of anodized alumina, the average distance between the convex portions is about 100 to 200 nm, and therefore 250 nm or less is particularly preferable.

The average interval between the convex portions is preferably 20 nm or more from the viewpoint of easy formation of the convex portions.
The average interval between the convex portions was measured by measuring 10 points or 50 points between the adjacent convex portions (distance from the center of the convex portion to the center of the adjacent convex portion) by electron microscope observation, and averaged these values. Is.

As for the height of a convex part, when an average space | interval is 100 nm, 80-500 nm is preferable, 120-400 nm is more preferable, 150-300 nm is especially preferable. If the height of the protrusion is 80 nm or more, the reflectance is sufficiently low and the wavelength dependence of the reflectance is small. If the height of a convex part is 500 nm or less, the scratch resistance of a convex part will become favorable.
The height of the convex portion is a value obtained by measuring the distance between the topmost portion of the convex portion and the bottommost portion of the concave portion existing between the convex portions when observed with an electron microscope at a magnification of 30000 times.

The aspect ratio of the convex portion (height of the convex portion / average interval between the convex portions) is preferably 0.8 to 5.0, more preferably 1.2 to 4.0, and 1.5 to 3.0. Particularly preferred. When the aspect ratio of the convex portion is 1.0 or more, the reflectance is not sufficiently low, and the wavelength dependency of the reflectance is small.
If the aspect ratio of the convex portion is 5.0 or less, the scratch resistance of the convex portion is good.

  The shape of the convex part is a shape in which the convex sectional area in the direction perpendicular to the height direction continuously increases in the depth direction from the outermost surface, that is, the sectional shape in the height direction of the convex part is a triangle, trapezoid, A shape such as a bell shape is preferred.

  The difference between the refractive index of the cured resin layer 44 and the refractive index of the substrate 42 is preferably 0.20 or less, more preferably 0.10 or less, and particularly preferably 0.05 or less. When the refractive index difference is 0.20 or less, reflection at the interface between the cured resin layer 44 and the base material 42 is suppressed.

By the way, when the surface has a fine concavo-convex structure, if the surface is made of a hydrophobic material, super water repellency can be obtained by the lotus effect, and if the surface is made of a hydrophilic material, it is super hydrophilic. Is known to be obtained.
When the material of the cured resin layer 44 is the hydrophobic material described above, the water contact angle on the surface of the fine uneven structure is preferably 90 ° or more, more preferably 110 ° or more, and particularly preferably 120 ° or more. If the water contact angle is 90 ° or more, water stains are less likely to adhere, so that sufficient antifouling properties are exhibited. Moreover, since water does not adhere easily, anti-icing can be expected.
In order to set the water contact angle on the surface of the fine uneven structure of the cured resin layer 44 to 90 ° or more, an active energy ray-curable resin composition containing the hydrophobic material described above may be used.

On the other hand, when the material of the cured resin layer 44 is the above-described hydrophilic material, the water contact angle on the surface of the fine uneven structure is preferably 25 ° or less, more preferably 23 ° or less, and particularly preferably 21 ° or less. If the water contact angle is 25 ° or less, the dirt adhering to the surface is washed away with water and oil dirt is less likely to adhere, so that sufficient antifouling properties are exhibited. The water contact angle is preferably 3 ° or more from the viewpoint of suppressing the deformation of the fine concavo-convex structure due to water absorption of the cured resin layer 44 and the accompanying increase in reflectance.
In order to set the water contact angle of the surface of the fine uneven structure of the cured resin layer 44 to 25 ° or less, an active energy ray-curable resin composition containing the hydrophilic material described above may be used.

<Effect>
In the transparent film obtained by the present invention, the inverted fine concavo-convex structure of the mold is accurately transferred, and optical distortion defects are suppressed.

<Application>
Applications of transparent films include antireflective articles, antifogging articles, antifouling articles, water repellent articles, and more specifically, antireflection for displays, automobile meter covers, automobile mirrors, automobile windows, organic or inorganic electro Examples include a luminescence light extraction efficiency improving member, a solar cell member, an optical waveguide, a relief hologram, a lens, a polarization separation element, and a cell culture sheet.

  For example, when a transparent film is used as an antireflection film, the surface of an object such as an image display device (liquid crystal display device, plasma display panel, electroluminescence display, cathode tube display device, etc.), lens, show window, spectacle lens, etc. In addition, a transparent film is applied.

In addition, when the part where the transparent film is pasted is a three-dimensional shape, an article having a fine concavo-convex structure on the surface is manufactured in advance using a substrate having a shape corresponding thereto, and this is pasted on a predetermined part of the object. You can attach it.
When the object is an image display device, not only the surface thereof, but also a transparent film may be attached to the front plate, or the front plate itself is composed of an article having a fine uneven structure on the surface. May be.

  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 with the oxide film formed on the surface is cut, platinum is deposited on the surface and cross section for 1 minute, and accelerated using a field emission scanning electron microscope (JEOL Ltd., “JSM-7400F”). Observe the surface under a voltage of 3.00 kV, measure the pore spacing (distance from the center of the pore to the center of the adjacent pore) at 10 points, and use the average value as the average spacing between adjacent pores. It was.
Similarly, the longitudinal section of the mold was observed in the same manner, and the distance between the bottom of the pores and the top of the convex portions existing between the pores was measured at 10 points, and the average value was measured. The average depth. The shape of the pores was confirmed.

<Measurement of the number of dents formed on the mold surface>
A part of a mold having an oxide film formed on the surface thereof is shaved, platinum is vapor-deposited on the surface for 1 minute, and an acceleration voltage of 10.10 is applied using a field emission scanning electron microscope (“JSM-7400F” manufactured by JEOL Ltd.). The surface was observed under the condition of 00 kV, and the number of dents having an equivalent circle diameter of 0.4 to 10.0 μm was measured and converted to the number per 1 mm ² .

<Measurement of initial peel force>
The peel force when the transparent film to be produced first using the mold a and the mold a is separated is measured with a 180 ° peel tester (manufactured by IMADA, “ZP-5N”). Was the initial peel force.

<Measurement of reflectance>
A transparent film was attached to a black acrylic plate (Mitsubishi Rayon Co., Ltd., Acrylite EX502) via a non-carrier film (Lintec Co., Ltd., "OPTERIA MO-3006C"), and a spectrophotometer (Hitachi Co., Ltd., "U- 4100 "), the relative reflectance between wavelengths 380 nm and 780 nm was measured under the condition of an incident angle of 5 °. Based on the reflectance at a wavelength of 550 nm, the following criteria were used for evaluation.
A: The reflectance at 550 nm is 1.0% or less.
X: The reflectance of 550 nm is more than 1.0%.

<Measurement of haze>
A transparent film is pasted on a slide glass (manufactured by Matsunaga Glass Industrial Co., Ltd., “S9112”) via a non-carrier film (manufactured by Lintec Co., Ltd., “OPTERIA MO-3006C”), and a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., “NDH2000”). )) To measure the transmittance.

<Appearance evaluation>
Appearance evaluation uses LED light (Asahi Electric Co., Ltd. "DOP-XRE301"), observes a transparent film visually in a dark room, and measures the number of optical distortion defects with a diameter of about 1 to 2 mm. Evaluation was made according to the following criteria.
○: Occurrence frequency of appearance defects 0 to 4 per 0.1 m ² Δ: Occurrence frequency of appearance defects 5 to 10 per 0.1 m ² ×: Generation frequency of appearance defects 11 or more per 0.1 m ²

<Manufacture of molds>
(Manufacture of mold a)
As the aluminum base, an aluminum plate having a thickness of 2 mm and a 10 cm square containing 99.87% aluminum and containing 0.10% magnesium was used. Further, as a polishing body, a polyester non-woven fabric and a foamed polyurethane suede polishing pad were used.
In accordance with the following steps, a mold a having an inverted fine concavo-convex structure on the surface having a wavelength of visible light or less was manufactured.

Step (a):
The surface of the aluminum substrate was treated (polished) with an aqueous solution (polishing slurry) having a pH of 2.1 containing alumina particles having an average particle diameter of 0.1 μm as an abrasive. For polishing, the polishing body was held by hand and moved at a speed of about 1 reciprocation / second, and the entire surface of the aluminum base was polished for 20 minutes and then washed with water (first polishing treatment).
Next, the surface of the aluminum substrate that had been subjected to the polishing treatment was further processed (polished) using a polishing liquid. As the polishing liquid, an aqueous solution (polishing slurry) having a pH of 10.1 and containing silica fine particles having a sodium dithionite concentration of 500 ppm and a particle diameter of nanometer scale as an abrasive was used. The aqueous solution was prepared by diluting a silica fine particle-containing polishing agent (manufactured by Fujimi Incorporated) previously subjected to nitrogen bubbling for 1 hour with ion-exchanged water in which sodium dithionite was dissolved. In the polishing, the above-mentioned polishing body was held by hand and moved at a speed of about 1 reciprocation / second, and the entire surface of the aluminum substrate was polished for 20 minutes and then washed with water (second polishing treatment).

Step (b):
The aluminum substrate surface-treated in the step (a) was anodized in a 0.3 M oxalic acid aqueous solution at a direct current of 40 V and a temperature of 16 ° C. for 30 minutes to form an oxide film on the surface of the aluminum substrate. .

Step (c):
The aluminum base material on which the oxide film was formed in step (b) was immersed in a 6% by mass phosphoric acid / 1.8% by mass chromic acid mixed aqueous solution for 6 hours to remove the entire oxide film.

Step (d):
The aluminum substrate after the step (c) was anodized in a 0.3 M oxalic acid aqueous solution at a direct current of 40 V and a temperature of 16 ° C. for 30 seconds to form an oxide film on the surface of the aluminum substrate.

Step (e):
The aluminum base material on which the oxide film was formed in the step (d) was immersed in 5% by mass phosphoric acid at 32 ° C. for 8 minutes to carry out pore diameter expansion treatment.

Step (f):
The aluminum substrate after the step (e) was anodized in a 0.3 M oxalic acid aqueous solution for 30 seconds under the conditions of a direct current of 40 V and a temperature of 16 ° C.

Step (g):
The step (e) and the step (f) are repeated four times in total, and finally the step (e) is performed, and anodized alumina having substantially conical pores with an average interval of 100 nm and a depth of 180 nm is the surface. A 10 cm square plate-shaped mold was obtained.

Steps (h) to (k), (m):
The obtained mold was washed with deionized water, and then water on the surface was removed by air blow.
Next, after immersing the mold in a 0.1% by weight diluted solution of TDP-8 (manufactured by Nikko Chemicals) for 10 minutes, the mold was slowly pulled up from the diluted solution, and the mold was air-dried overnight. A 10 cm square plate-shaped mold a surface-treated with an external mold release agent was obtained.
When the number of dents scattered on the surface of the obtained mold a was measured, it was 4075 pieces / mm ² .

(Manufacture of mold b)
As the aluminum base material, the step (a) is carried out in the same manner as in the production of the mold a except that roll aluminum containing 99.67% aluminum and containing 0.30% magnesium is used. Carried out.
Subsequently, in accordance with the following steps, a mold b having an inverted fine concavo-convex structure on the surface having a wavelength of visible light or less was manufactured.

Step (b):
The aluminum substrate surface-treated in the step (a) was anodized for 6 hours in a 0.3 M oxalic acid aqueous solution at a direct current of 40 V and a temperature of 16 ° C. to form an oxide film on the surface of the aluminum substrate. .

Step (c):
The aluminum base material on which the oxide film was formed in step (b) was immersed in a 6% by mass phosphoric acid / 1.8% by mass chromic acid mixed aqueous solution for 6 hours to remove the entire oxide film.

Step (d):
The aluminum substrate after the step (c) was anodized for 20 seconds in a 0.3 M oxalic acid aqueous solution under conditions of a direct current of 40 V and a temperature of 16 ° C. to form an oxide film on the surface of the aluminum substrate.

Step (e):
The aluminum base material on which the oxide film was formed in the step (d) was immersed in 5% by mass phosphoric acid at 32 ° C. for 8 minutes to carry out pore diameter expansion treatment.

Step (f):
The aluminum substrate after the step (e) was anodized in a 0.3 M oxalic acid aqueous solution for 20 seconds under the conditions of a direct current of 40 V and a temperature of 16 ° C.

Step (g):
The step (e) and the step (f) are repeated four times in total, and finally the step (e) is performed, and anodized alumina having substantially conical pores with an average interval of 100 nm and a depth of 220 nm is the surface. A roll-shaped mold formed in the above was obtained.

Steps (h) to (k), (m):
The obtained mold was washed with deionized water, and then water on the surface was removed by air blow.
Next, after immersing the mold in a 0.1% by weight diluted solution of TDP-8 (manufactured by Nikko Chemicals) for 10 minutes, the mold was slowly pulled up from the diluted solution, and the mold was air-dried overnight. A roll-shaped mold b surface-treated with an external release agent was obtained.
When the number of dents scattered on the surface of the obtained mold b was measured, it was 5184 / mm ² .

<Preparation of active energy ray-curable resin composition>
Each component was mixed according to the following compounding compositions, and active energy ray-curable resin composition AD was prepared.

(Composition composition of active energy ray-curable resin composition A)
-Trimethylolethane / acrylic acid / succinic anhydride condensation reaction product: 70 parts by mass,
Polyethylene glycol diacrylate (manufactured by Toagosei Co., Ltd., “Aronix M260”): 20 parts by mass
2-hydroxyethyl acrylate: 3 parts by mass
Methyl acrylate: 7 parts by mass
(Poly) oxyalkylene alkyl phosphate ester compound (manufactured by Accel Corp., “Mold with INT-1856”): 0.3 part by mass,
1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Japan, “Irgacure 184”): 1 part by mass,
Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (manufactured by BASF Japan, “Irgacure 819”): 0.1 part by mass.

(Composition composition of active energy ray-curable resin composition B)
Dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., “Kayarad DPHA”): 20 parts by mass,
Pentaerythritol triacrylate (Daiichi Kogyo Seiyaku Co., Ltd., “PET-3”): 20 parts by mass
EO-modified dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., “Kayarad DPEA-12”): 30 parts by mass
Polyethylene glycol diacrylate (manufactured by Toagosei Co., Ltd., “Aronix M260”): 30 parts by mass
-(Poly) oxyalkylene alkyl phosphate compound (manufactured by Nikko Chemicals, "NIKKOL TDP-2"): 0.5 parts by mass,
1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Japan, “Irgacure 184”): 1 part by mass,
Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (manufactured by BASF Japan, “Irgacure 819”): 0.5 part by mass.

(Composition composition of active energy ray-curable resin composition C)
-Trimethylolethane / acrylic acid / succinic anhydride condensation reaction product: 70 parts by mass,
Polyethylene glycol diacrylate (manufactured by Toagosei Co., Ltd., “Aronix M260”): 20 parts by mass
2-hydroxyethyl acrylate: 3 parts by mass
Methyl acrylate: 7 parts by mass
(Poly) oxyalkylene alkyl phosphate ester compound (manufactured by Accel Corp., “Mold with INT-1856”): 0.05 parts by mass
1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Japan, “Irgacure 184”): 1 part by mass,
Bis (2,4,6-trimethylbenzoyl) -phenyl phosphine oxide (manufactured by BASF Japan, “Irgacure 819”): 0.1 parts by mass.

(Composition composition of active energy ray-curable resin composition D)
Dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., “Kayarad DPHA”): 20 parts by mass,
Pentaerythritol triacrylate (Daiichi Kogyo Seiyaku Co., Ltd., “PET-3”): 20 parts by mass
EO-modified dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., “Kayarad DPEA-12”): 30 parts by mass
Polyethylene glycol diacrylate (manufactured by Toagosei Co., Ltd., “Aronix M260”): 30 parts by mass
-(Poly) oxyalkylene alkyl phosphate compound (manufactured by Nikko Chemicals, "NIKKOL TDP-2"): 0.1 parts by mass,
1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Japan, “Irgacure 184”): 1 part by mass,
Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (manufactured by BASF Japan, “Irgacure 819”): 0.5 part by mass.

"Example 1"
An active energy ray-curable resin composition A is dropped on the surface of the mold a on which the inverted fine concavo-convex structure is formed, and a polyethylene terephthalate film (“Cosmo Shine A-4300” manufactured by Toyobo Co., Ltd.) is used as a base material. (Thickness: 75 μm), and coating while spreading, and then irradiating the substrate with ultraviolet rays with an energy of 1000 mJ / cm ² using an electrodeless UV lamp (Fusion UV Systems, “Light Hammer 6”). Then, the active energy ray-curable resin composition A was cured to form a cured resin layer on the surface of the substrate. The base material on which the cured resin layer was formed and the mold were separated to obtain a transparent film having a fine concavo-convex structure (a structure in which the inverted fine concavo-convex structure of the mold a was transferred) on the surface.
The same operation was repeated 5 times in total to produce 5 transparent films.

In the first production of the transparent film, the peel force when the substrate on which the cured resin layer was formed and the mold was separated was measured with a 180 ° peel tester. The results are shown in Table 1.
Moreover, about the transparent film manufactured for the 5th time, the reflectance and haze were measured and external appearance evaluation was performed. These results are shown in Table 2.

"Example 2"
For the measurement of peel force, a flat mold c produced under the same conditions as the mold b except for the shape was used, the active energy ray-curable resin composition B was used, and a triacetyl cellulose film ( A transparent film was produced in the same manner as in Example 1 except that “TAC film TD80ULM” (thickness: 80 μm) manufactured by FUJIFILM Corporation was used.
In the first production of the transparent film, the peel force when the substrate on which the cured resin layer was formed and the mold was separated was measured with a 180 ° peel tester. The results are shown in Table 1.

  Separately, a transparent film was continuously produced using the production apparatus shown in FIG. 2 as follows. The roll-shaped mold 20 is a mold b, the active energy ray-curable resin composition 24 is an active energy ray-curable resin composition B, and the substrate (base film) 42 is triacetyl. A cellulose film (manufactured by Fuji Film, “TAC film TD80ULM”, thickness: 80 μm) was used.

While the belt-shaped base film 42 is moved along the surface of the roll-shaped mold 20 in synchronization with the rotation of the roll-shaped mold 20, between the roll-shaped mold 20 and the base film 42 from the tank 22. An active energy ray-curable resin composition 24 was supplied.
By irradiating the active energy ray-curable resin composition 24 with ultraviolet rays having an integrated light quantity of 1000 mJ / cm ² from the base film 42 side, the active energy ray-curable resin composition 24 is cured, whereby A cured resin layer 44 was formed on the surface.
A transparent film was continuously produced by peeling the base film 42 having the cured resin layer 44 formed on the surface from the roll mold 20 by the peeling roll 32.
When the transparent film was manufactured 200 m, the movement of the base film 42 was stopped. About the transparent film obtained just before the stop, the reflectance and haze were measured and the appearance was evaluated. These results are shown in Table 2.

"Comparative Example 1"
Except that the active energy ray-curable resin composition C was used and an acrylic film (manufactured by Mitsubishi Rayon Co., Ltd., “Acryprene (registered trademark) HBK003”, thickness: 100 μm) was used as in Example 1, Five transparent films were produced.
In the first production of the transparent film, the peel force when the substrate on which the cured resin layer was formed and the mold was separated was measured with a 180 ° peel tester. The results are shown in Table 1.
Moreover, about the transparent film manufactured for the 5th time, the reflectance and haze were measured and external appearance evaluation was performed. These results are shown in Table 2.

"Comparative Example 2"
About the measurement of peeling force, it is the same as that of Example 1 except using the flat mold c produced on the conditions similar to the mold b except the shape, and using the active energy ray curable resin composition D. Thus, a transparent film was produced.
In the first production of the transparent film, the peel force when the substrate on which the cured resin layer was formed and the mold was separated was measured with a 180 ° peel tester. The results are shown in Table 1.

  Separately, the transparent film was continuously manufactured using the manufacturing apparatus shown in FIG. Specifically, the active energy ray-curable resin composition D is used, and a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., “Cosmo Shine A-4300”, thickness: 75 μm) is used as the base material (base film) 42. A transparent film was continuously produced in the same manner as in Example 2 except that the reflectance and haze were measured for the transparent film at the time when 200 m was produced, and the appearance was evaluated. These results are shown in Table 2.

The abbreviations in Tables 1 and 2 are as follows.
PET: Polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., “Cosmo Shine A-4300”, thickness 75 μm).
TAC: Triacetyl cellulose film (manufactured by Fuji Film, “TAC film TD80ULM”, thickness 80 μm).
PMMA: acrylic film (manufactured by Mitsubishi Rayon Co., Ltd., “Acryprene (registered trademark) HBK003”, thickness: 100 μm).

As is clear from the results in Tables 1 and 2, in Examples 1 and 2, pits having a diameter equivalent to a circle of 0.4 to 10.0 μm or more are scattered with visible light wavelengths or more, and the portion has a fine concavo-convex structure. Even in the case of using an active energy ray-curable resin composition having an initial peel strength of 7 N / m or less in the 180 ° peel test, the occurrence of optical distortion defects could be suppressed.
On the other hand, in Comparative Examples 1 and 2, since the initial peel force in the 180 ° peel test is more than 7 N / m, an optical distortion defect occurs, and the transparent films obtained in Comparative Examples 1 and 2 are inferior in appearance. It was.

The method for producing a transparent film of the present invention is useful for efficient mass production of transparent films such as antireflection articles, antifogging articles, antifouling articles, water repellent articles, and cell culture sheets.
The transparent film obtained by the present invention is suitable as an antireflection article, an antifogging article, an antifouling article, a water repellent article, a cell culture sheet, and the like.

DESCRIPTION OF SYMBOLS 10 Aluminum base material 12 Pore 14 Oxide film 16 Pore generation | occurrence | production point 18 Mold 20 Roll-shaped mold 22 Tank 24 Active energy ray curable resin composition 26 Pneumatic cylinder 28 Nip roll 30 Active energy ray irradiation apparatus 32 Peeling roll 40 Transparent Film 42 Base material (Base film)
44 Cured resin layer 46 Convex part 50 Mold 52 Concave part 52a Bottom part 52b Opening part

Claims (4)

A method for producing a transparent film having a fine concavo-convex structure consisting of a plurality of convex portions with a period of 400 nm or less on the surface,
(I) Surface treatment after treating the surface of an aluminum substrate containing 0.05% or more of a substance having a purity of 99.0 to 99.9% and a standard electrode potential lower than that of aluminum with an acidic or alkaline solution Inversion of the fine concavo-convex structure comprising a plurality of concave portions on the surface of the aluminum base material on which the pits having an equivalent circle diameter of 0.4 to 10.0 μm are scattered on the surface. Producing a mold having a structure;
(II) An active energy ray-curable resin composition is supplied to the surface of the mold having the inverted structure of the fine concavo-convex structure and activated by irradiating the active energy ray-curable resin composition with active energy rays. Curing the energy ray curable resin composition, obtaining a transparent film having the fine uneven structure on the surface;
(III) separating the transparent film and the mold;
Have
The manufacturing method of a transparent film whose initial peeling force by the 180 degree peeling test at the time of isolate | separating the hardened | cured material of the said active energy ray curable resin composition and the said mold is 7 N / m or less.   The method for producing a transparent film according to claim 1, wherein the active energy ray-curable resin composition contains a polymerizable compound and a release agent, and the release agent is a (poly) oxyalkylene alkyl phosphate ester compound.   The method for producing a transparent film according to claim 2, wherein the active energy ray-curable resin composition contains 0.2 to 1.5 parts by mass of the release agent with respect to 100 parts by mass of the polymerizable compound. .   The transparent substance according to any one of claims 1 to 3, wherein the substance having a lower standard electrode potential than aluminum is at least one selected from the group consisting of magnesium, lithium, potassium, barium, calcium, sodium, and titanium. A method for producing a film.

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