JP4848161B2 - Antireflection film manufacturing method and antireflection film manufacturing stamper manufacturing method - Google Patents

Description

The present invention is formed on the surface of the polymer film, a method of manufacturing a reflection preventing film for reducing the reflection in the visible light region, and a method of manufacturing a stamper for forming the anti-reflection film.

  In various display devices for information equipment, polymer films (polymer films) are widely used, but in order to ensure good visibility, it is necessary to form an antireflection layer to suppress reflected light It is said. Normally, a multilayer film composed of dielectric materials having different refractive indexes is used as the antireflection layer. However, a vacuum deposition method or a sputtering method is used to form the dielectric layer. The layer formation has a problem of requiring an expensive apparatus and a great production time.

  On the other hand, a method is known in which the reflectance is reduced by providing a protrusion-like shape on the surface of the polymer film and forming a layer whose refractive index continuously changes. In order to impart a protrusion shape to the polymer film, a method is generally used in which a stamper having a depression array corresponding to the protrusion shape is prepared and the polymer film is processed based on the stamper.

  The depression formed in the stamper for forming the protrusion shape on the surface of the polymer film has a fine period compared to the wavelength of light, and in order to sufficiently attenuate the reflectance in the visible light region, It is necessary to have a depth of about 1/4 (for example, Patent Document 1). At this time, the recess needs to have a tapered shape because it is necessary to continuously change the refractive index.

  In order to perform the formation of the depression array satisfying such conditions, a technique combining electron beam lithography, photolithography technique, and dry etching technique is generally used. However, these methods have a problem that it takes a lot of time to process, so that it is difficult to increase the area, and an expensive apparatus is required for processing.

As a method for forming a taper-shaped protrusion on the surface of a polymer film with a large area at a low cost, a method using anodized porous alumina having tapered pores whose pore diameters are continuously changed was previously applied by the present applicant. It has been proposed (Patent Document 2). However, at the stage of this proposal, the pore diameter of the anodized porous alumina used as a template was not necessarily optimized in the film thickness direction, so the refractive index change on the polymer film surface was optimized. However, there is a problem that the antireflection characteristics obtained are limited.
JP 2003-43203 A Japanese Patent Laid-Open No. 2005-156695

  As described above, it is difficult to produce a stamper capable of processing a large area at a low cost by the method using lithography, and the method using an anodized porous alumina having tapered pores is also optimized. Therefore, it has been difficult to provide the antireflection characteristics.

Accordingly, an object of the present invention is to provide a method for producing an antireflection film capable of efficiently forming an optimal antireflection structure on the surface of a polymer film using anodized porous alumina as a mold in order to solve the above-described problems in the prior art. , and to provide a manufacturing method of efficiently formable stamper its antireflection film.

In order to solve the above-mentioned problems, the present invention combines the anodic oxidation and the pore diameter expansion treatment, and adjusts the respective treatment conditions, so that the pore diameter of the pore is more optimal in terms of the longitudinal cross-sectional shape of the pore. By using anodized porous alumina having continuously changed pores as a template, it is possible to produce an antireflective polymer film. That is, the manufacturing method of the antireflection film according to the present invention, the anodic oxidation and pore diameter-Daehwa process, repeated several times to adjust the respective processing conditions, the final processing with a hole diameter-Daehwa treatment, said last By setting the time of the pore diameter enlargement treatment as the treatment of the treatment time to be different from the time of the pore diameter enlargement treatment in the previous repeated treatment, it is possible to see from the opening of the pore as viewed in the longitudinal sectional shape of the pore. template in the pore depth direction toward the bottom, to produce an anodized porous alumina having pores of bell-shaped inner surface of the pores varies curvedly with pore diameter of the pores decreases, the anodic-oxide porous alumina Or by using a stamper produced by using the anodized porous alumina as a mold, a protrusion having a shape corresponding to the shape of the pores on the surface of the polymer material Other consists method characterized by forming an array of indentations. Typically, as shown in the examples described later, the step of performing the pore size enlargement process after anodizing is repeated n times, and the nth pore size enlargement process is performed for the first to (n-1) th times. By making the treatment time longer than the pore diameter enlargement treatment of the pores, the pore diameter on the bottom side of the pores in the pore depth direction from the opening to the bottom of the pores in the longitudinal cross-sectional shape of the pores An anodized porous alumina having a bell-shaped pore in which the inner diameter of the pore changes in a curvilinear manner and the inner diameter of the pore changes relatively sharply as compared with the pore diameter of the pore on the opening side of the pore. By using oxidized alumina as a template, or by using a stamper made using the anodized porous alumina as a template, an array of protrusions or depressions having a shape corresponding to the shape of the pores is formed on the surface of the polymer material. To do Method for producing an antireflection film according to symptoms can be mentioned.

In this antireflection film manufacturing method, the vertical cross-sectional shape of the pores corresponding to the protrusions formed on the surface of the polymer material is, for example, the pore depth direction from the opening to the bottom of the pores The pore diameter on the opening side of the pores can be formed in a shape that decreases relatively gently as compared with the pore diameter on the bottom side of the pores . In addition, as the vertical cross-sectional shape of the pore corresponding to the depression formed on the surface of the polymer material, for example, the change in pore diameter as viewed along the pore depth direction from the opening to the bottom of the pore With respect to the above, it is also possible to form a shape in which the pore diameter on the opening side of the pore is relatively abruptly reduced as compared with the pore diameter on the bottom side of the pore .

  Moreover, in the manufacturing method of the antireflection film, a more optimal antireflection film can be produced by using anodized porous alumina having a pore period of 50 nm to 300 nm and a pore depth of 100 nm or more as a template.

  In addition, an anode having high pore arrangement regularity is obtained by using anodized porous alumina prepared by anodizing at a constant voltage for a long time, once removing the oxide film, and again anodizing under the same conditions. It becomes possible to use oxidized porous alumina as a mold.

  As the anodized porous alumina to be used, for example, anodized porous alumina prepared using an oxalic acid as an electrolytic solution at a chemical conversion voltage of 30 V to 60 V can be used. The produced anodized porous alumina can also be used. By using such anodized porous alumina, it becomes possible to use a dent or protrusion arrangement having higher regularity as a template.

  Further, in the production of anodized porous alumina, a fine depression can be formed on the aluminum surface prior to anodization, and this can be used as a pore generation point during anodization. As a result, it is possible to obtain a template having an indentation or projection arrangement having an arbitrary arrangement.

Antireflection coating definitive to the present invention has been produced by such a method, the surface projections or depressions arranged in the formed shape with the target, those having excellent antireflection performance. By forming this antireflection film on the surface of a light-transmitting polymer film, for example, it is possible to exhibit target antireflection performance in various applications.

A method for producing a stamper for producing an antireflection film according to the present invention is a method for producing a stamper for use in forming the projections or depressions of an antireflection film in which an array of projections or depressions is formed on the surface of a polymer material, the anodic oxidation and pore diameter-Daehwa process, repeated several times to adjust the respective processing conditions, the final processing with a hole diameter-maximization process, the hole diameter-maximization process as the process in said last time the previous By setting the treatment time to be different from the pore size enlargement treatment time in the repeated treatment , the pore diameter in the pore depth direction from the opening to the bottom of the pore is seen in the longitudinal sectional shape of the pore. how the inner surface of the pores to produce an anodized porous alumina having pores curve varying bell-shaped, which comprises using the anodised porous alumina as a template with but decreasing Ranaru. Typically, as shown in the examples described later, a method of manufacturing a stamper for use in forming the protrusions or depressions of an antireflection film in which an array of protrusions or depressions is formed on the surface of a polymer material, The step of performing the pore size enlargement process after anodizing is repeated n times, and the nth pore size enlargement treatment is made longer than the first to (n-1) th pore size enlargement treatment, Looking at the longitudinal cross-sectional shape of the pore, the pore diameter on the bottom side of the pore is smaller than the pore diameter on the pore opening side in the depth direction of the pore from the opening to the bottom of the pore. Anodized porous alumina having bell-shaped pores whose inner surface changes in a curved manner while decreasing relatively rapidly, and using the anodized porous alumina as a template, antireflection A method for manufacturing a stamper for film preparation is listed. Rukoto can.

Antireflection film fabrication stamper definitive to the present invention consists of those produced by such a method.

According to the present invention, compared with the conventional method, more conveniently, also enables the formation of mold shape of the pores is based on anodized porous alumina, which is controlled to a more optimal shape, as a result, the visible light region production of an antireflection layer with reduced reflections at, furthermore, it is possible to manufacture a stamper for forming the anti-reflection layer.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a method for producing anodized porous alumina used as a mold in the present invention. Anodization and pore size enlargement treatment are repeated a plurality of times by adjusting the respective treatment conditions, for example, treatment time , and the final treatment is the pore size enlargement treatment, and the time of the pore size enlargement treatment as the last treatment In the pore depth direction from the opening of the pore toward the bottom, as seen in the vertical cross-sectional shape of the pore, by setting the treatment time different from the time of the pore diameter enlargement treatment in the previous repeat treatment , the inner surface of the pores with a pore diameter of the pores is reduced to produce an anodized porous alumina having pores curve varying bell-shaped. As shown in FIG. 1, the anodized porous alumina 2 is formed on the surface of the aluminum substrate 1, but the pores 3 of the anodized porous alumina 2 have a cylindrical shape in the initial stage. As it is, it is difficult to use it as a mold for forming an antireflective film. In the present invention, by combining the anodic oxidation and the pore diameter enlargement process by etching, the pore diameter of the pore 3 finally decreases in the depth direction of the pore 3 when viewed from the longitudinal cross-sectional shape of the pore 3, and the inner surface of the pore. The anodized porous alumina 2 having the pores 3 having a shape that changes in a curve is produced. In the example shown in FIG. 1, the final longitudinal cross-sectional shape of the pore 3 is a bell shape, that is, the pore diameter gradually decreases at the beginning (that is, on the pore opening side) at the beginning. The inner surface of the pore changes in a curved manner, but the pore diameter decreases more rapidly from the middle (that is, on the bottom side of the pore ) and the inner surface of the pore changes in a curved shape. ing. After anodizing for a predetermined time to form pores having a desired depth, the pores are enlarged by being immersed in an appropriate acid solution. Thereafter, anodization is performed again to form a hole having a smaller hole diameter compared to the first stage. By repeating this operation and adjusting each processing condition in each stage, the anodized porous alumina 2 having a target bell-shaped shape can be obtained. At this time, a smoother curve shape can be obtained by increasing the number of steps. In particular, by adjusting the anodizing time and the pore diameter expansion processing time, it is possible to form pores with various curved longitudinal sections, and design an optimal refractive index change along with the period and pore depth. It becomes possible.

As shown in FIG. 2, a porous alumina having pores in which the pore diameter formed in this manner changes in the depth direction and the inside surface of the pore changes in a longitudinal cross-sectional shape in a curved shape is used as a template. By transferring this structure to the material 4 (polymer film), an antireflection structure having protrusions on the surface can be obtained.

  Further, as shown in FIG. 3, the structure of the obtained anodized porous alumina 2 is used as a mold, and a mold having the same shape is obtained by using a negative mold material 5 such as metal, and this mold (mold by the negative mold material 5) is positive. If the mold material 6 is provided, it is possible to obtain the stamper 7 by removing the mold made of the negative mold material 5. The stamper 7 can function as a projection pattern forming mold for the polymer material forming the antireflection film. Such a stamper 7 is effective as a structure having durability, wear resistance, or release characteristics.

In the present invention, as shown in FIG. 4, it is possible to form an antireflection structure including a depression pattern in addition to the projection pattern. In this case, a stamper 8 made of a material such as a metal using an anodized porous alumina 2 having a pore whose pore diameter changes in the depth direction and has a longitudinal cross-sectional shape with a curved inner surface of the pore changed as a mold. Used as a mold for forming a recess pattern. If the mold obtained by such a method is used, it is possible to produce an antireflection film having a pattern of dents whose size changes in the depth direction and whose inner surface is curved in a longitudinal sectional shape .

The longitudinal cross-sectional shape of the pores 3 of the anodized porous alumina 2 illustrated in FIG. 4 shows that the pore diameter decreases slightly abruptly at the beginning (that is, on the opening side of the pores) in the pore depth direction . The inner surface changes in a curved manner, and the pore diameter decreases more gradually from the middle (that is, on the bottom side of the pore ) , and the inner surface of the pore is changed in a curved shape. 1 and FIG. 4, the pore 3 in which the pore diameter is reduced and the inner surface of the pore is changed in a curve is combined with anodization and pore diameter enlargement processing, and the respective treatment conditions are adjusted to different conditions. Can be formed.

In the present invention, further, anodization is performed for a relatively long period of time in advance before forming a pore having a longitudinal cross-sectional shape as described above, and the pore inner surface is curved and the pore diameter is reduced. By regularizing the pore arrangement of the oxidized porous alumina layer and then removing the alumina layer, a regular depression arrangement corresponding to the bottom of the porous alumina (called the barrier layer) is obtained on the aluminum surface, and the same voltage is again applied. By combining the anodic oxidation with the pore diameter expansion treatment, anodized porous alumina having pores with a predetermined vertical cross-sectional shape in which pores are regularly arranged from the outermost surface can be formed. That is, it is possible to form anodized porous alumina in which pores having a preferable longitudinal cross-sectional shape are arranged with higher regularity. In general, in anodized porous alumina, the regularity of the pore arrangement of the outermost surface portion formed at the initial stage of anodization is low. Although it may be difficult to use as a good non-reflective film, it becomes possible to obtain anodized porous alumina with pores arranged with high regularity based on the above method, and good non-reflective film Contributes to film formation. At this time, when oxalic acid is used as the electrolytic solution, a high voltage is formed at a conversion voltage of 30 to 60 V, more preferably at 40 V, and when sulfuric acid is used as the electrolytic solution, a high voltage is formed at a conversion voltage of 25 to 30 V. It is known that anodized porous alumina having properties can be obtained (for example, Masuda, Applied Physics, vol. 69, No. 5, p. 558 (2000)). The anodized porous alumina having a highly ordered hole array formed in this way can be used directly or more effectively for the production of a metal mold or the like.

  In the present invention, furthermore, by using a mold having projections in a desired arrangement, a micro-dent array is formed on the surface of the aluminum substrate, and then anodization and pore size expansion treatment at a formation voltage suitable for the recess spacing. By combining these, the depression becomes the starting point of hole generation, and it becomes possible to obtain anodized porous alumina having tapered holes having a hole arrangement corresponding to the protrusion arrangement of the mold. According to this method, anodized porous alumina having an arbitrary period and arrangement can be formed, which contributes to obtaining a good antireflection film. This method not only obtains anodized porous alumina having a highly ordered pore arrangement, but also contributes to the suppression of the occurrence of interference colors due to light interference, which is a problem when used as a display material. The anodized porous alumina having a highly ordered hole array formed in this way can be used directly or more effectively for the production of a metal mold or the like.

Next, based on an Example, this invention is demonstrated further more concretely.
Example 1 (Preparation of an antireflection film prepared using anodized porous alumina as a mold)
An aluminum plate with a purity of 99.99% was subjected to anodization for 15 seconds at a formation voltage of 40 V using 0.3 M oxalic acid aqueous solution as the electrolyte. After that, it was immersed in 5 wt% phosphoric acid at 30 ° C. for 3 minutes and subjected to a pore diameter expansion treatment. This operation was repeated 5 times, and after anodizing for 15 seconds under the same conditions, the pore size was increased for 15 minutes, resulting in a pore period of 100 nm, pore opening of 80 nm, bottom of 40 nm, and pore depth of 200 nm. An anodized porous alumina having a bell-shaped pore in the longitudinal section was obtained. A methyl methacrylate monomer containing 5% by weight of benzoyl peroxide as a polymerization initiator was filled in the pores, and then polymerized by irradiation with ultraviolet rays. After polymerization, the template was dissolved and removed to obtain a polymethyl methacrylate resin film having bell-shaped protrusions on the surface. FIG. 5 shows a view obtained by observing the anodized porous alumina 2 having bell-shaped pores obtained by this method with an electron microscope. FIG. 6 shows a view of the antireflection film 4 obtained using the anodized porous alumina 2 as a mold, as observed with an electron microscope.

  The present invention can be applied to any application that requires the formation of an antireflection film, and is particularly suitable for display devices for various information devices that require improved visibility.

It is a figure which shows the process of producing the anodic oxidation porous alumina which has the pore in which the pore diameter changed continuously with the desired curvilinear change rate in the film thickness direction by combining anodizing time and etching. It is a figure which shows the process of producing the anti-reflective film which has the protrusion shape which used the porous alumina which has the pore in which the pore diameter changed continuously in the film thickness direction as a casting_mold | template. It is a figure which shows the process of producing the stamper for protrusion pattern formation produced using the anodized porous alumina as a casting_mold | template. It is a figure which shows the process of producing the dent pattern formation stamper produced using the anodized porous alumina as a casting_mold | template. It is the figure which observed the anodized porous alumina which has a bell-shaped pore by the electron microscope. It is the figure which observed the anti-reflective film produced using the anodized porous alumina which has a bell-shaped pore as a casting_mold | template with the electron microscope.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aluminum base material 2 Anodized porous alumina 3 Pore 4 Polymer material (antireflection film) polymer 5 Negative mold material 6 Positive mold material 7 Stamper (mold for projection pattern formation)
8 Stamper (mold for forming recess pattern)

Claims (11)

The anodic oxidation and pore diameter-Daehwa process, repeated several times to adjust the respective processing conditions, the final processing with a hole diameter-maximization process, the hole diameter-maximization process as the process in said last time the previous By setting the treatment time to be different from the pore size enlargement treatment time in the repeated treatment , the pore diameter in the pore depth direction from the opening to the bottom of the pore is seen in the longitudinal sectional shape of the pore. Of anodized porous alumina having bell- shaped pores in which the inner surface of the pores changes in a curved manner as the amount of the pores decreases, and using the anodized porous alumina as a template, or using the anodized porous alumina as a template By using the produced stamper, an array of protrusions or depressions having a shape corresponding to the shape of the pores is formed on the surface of the polymer material. Method of manufacturing a stop film. The step of performing the pore size enlargement process after anodizing is repeated n times, and the nth pore size enlargement treatment is made longer than the first to (n-1) th pore size enlargement treatment, Looking at the longitudinal cross-sectional shape of the pore, the pore diameter on the bottom side of the pore is smaller than the pore diameter on the pore opening side in the depth direction of the pore from the opening to the bottom of the pore. Anodized porous alumina having bell-shaped pores whose inner surface is changed in a curvilinear manner while decreasing relatively abruptly is prepared, and the anodized porous alumina is used as a template, or the anodized porous A method of manufacturing an antireflection film, wherein an array of protrusions or depressions having a shape corresponding to the shape of the pores is formed on a surface of a polymer material by using a stamper manufactured using alumina as a mold. The vertical cross-sectional shape of the pore corresponding to the protrusion formed on the surface of the polymer material is related to the change in pore diameter as viewed along the pore depth direction from the opening to the bottom of the pore. 2. The method of manufacturing an antireflection film according to claim 1, wherein the opening side has a shape in which the hole diameter is relatively gradually reduced as compared with the hole diameter on the bottom side . The vertical cross-sectional shape of the pore corresponding to the depression formed on the surface of the polymer material is related to the change in pore diameter as viewed along the pore depth direction from the opening to the bottom of the pore. The method for producing an antireflection film according to claim 1, wherein the hole diameter on the opening side has a shape that is relatively abruptly reduced as compared with the hole diameter on the bottom side of the pore . Pore period 50 nm to 300 nm, using a pore depth 100nm or more of the anodized porous alumina, a manufacturing method of an antireflection film according to any one of claims 1-4. The reflection according to any one of claims 1 to 5 , wherein anodized porous alumina prepared by anodizing at a constant voltage for a long time, once removing the oxide film and anodizing again under the same conditions is used. Manufacturing method of prevention film. The manufacturing method of the anti-reflective film in any one of Claims 1-6 using the anodic oxidation porous alumina produced in the conversion voltage 30V-60V using oxalic acid as electrolyte solution. Using sulfuric acid as the electrolytic solution, using anodized porous alumina prepared in formation voltage 25V～30V, method for producing an antireflection film according to any one of claims 1-6. The antireflection film according to any one of claims 1 to 8 , wherein in the production of the anodized porous alumina, a fine depression is formed on the aluminum surface prior to anodization, and this is used as a pore generation point during anodization. Manufacturing method. A method of manufacturing a stamper for use in forming a projection or a depression of an antireflection film having a projection or depression array on the surface of a polymer material, wherein anodization and pore diameter enlargement treatment are performed under the respective treatment conditions. Adjusting and repeating a plurality of times, the last process is a pore size enlargement process, and the time of the pore size enlargement process as the last process is different from the time of the pore size enlargement process in the previous repeat process with, viewed in longitudinal section of the pores, the pore depth direction toward the bottom from the opening of the pores, changes the inner surface of the pores curvilinear with a pore size of the pores decreases bell A method for producing a stamper for producing an antireflection film, comprising producing anodized porous alumina having pores having a shape and using the anodized porous alumina as a template. A method of manufacturing a stamper for use in forming a projection or a depression of an antireflection film having a projection or depression array on the surface of a polymer material, the step of performing an enlargement process after anodizing By repeating the n-th pore size enlargement process longer than the first to (n-1) th pore size enlargement treatment, the pore opening portion is viewed in the shape of the longitudinal cross section of the pore. In the pore depth direction from the bottom to the bottom, the pore diameter on the bottom side of the pore decreases more rapidly than the pore diameter on the opening side of the pore, and the inner surface of the pore is curved. A method for producing a stamper for producing an antireflective film, comprising producing anodized porous alumina having bell-shaped pores that change into a shape, and using the anodized porous alumina as a template.

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