JP4824430B2 - Method for producing nanostructure - Google Patents

Abstract

A method of manufacturing structures includes a stripping step in which an aluminum member that includes an aluminum substrate and an anodized layer present on a surface of the aluminum substrate and that serves as a cathode is electrolyzed to strip the anodized layer from the aluminum substrate to obtain a structure composed of the anodized layer. Electrolysis in the stripping step is carried out in such a way that a current passes over a surface of the anodized layer. Structures having a well-ordered array of pits can be obtained in a short time without the use of substances such as chromic acid that are deleterious to the environment.

Description

The present invention relates to a method of manufacturing a nano-structure.

  In the technical fields of metal and semiconductor thin films, thin wires, dots, etc., the phenomenon of electrical, optical and chemical peculiarities can be seen by confining the movement of free electrons in a size smaller than a certain characteristic length. It has been known. Such a phenomenon is called “quantum mechanical size effect (quantum size effect)”. Research and development of functional materials applying such a unique phenomenon is being actively conducted. Specifically, a material having a structure finer than several hundred nm is referred to as “nanostructure” or “fine structure”, and is one of the objects of material development.

  As a method for manufacturing such a fine structure, for example, a method for directly manufacturing a nano structure by a semiconductor processing technique including a fine pattern forming technique such as photolithography, electron beam exposure, and X-ray exposure can be given.

In particular, much research has been conducted on methods for producing nanostructures having a regular microstructure.
For example, as a method for forming a regular structure in a self-regulating manner, an anodized alumina film (anodized film) obtained by subjecting aluminum to an anodizing treatment in an electrolytic solution can be mentioned. It is known that a plurality of fine pores (micropores) having a diameter of about several nm to several hundred nm are regularly formed in the anodized film. By using this self-ordering of the anodized film and obtaining a perfectly regular arrangement, theoretically, hexagonal prism cells with a regular hexagonal bottom centered around the micropores are formed, and adjacent micropores are formed. It is known that the connecting line forms an equilateral triangle.
For example, Non-Patent Document 1 describes an anodized film in which the pore diameter variation of micropores is 3% or less. Non-Patent Document 2 describes that pores are spontaneously formed in the anodized film as the oxidation proceeds. Non-Patent Document 3 also proposes forming an Au dot array on a Si substrate using a porous oxide film as a mask.

  The greatest feature of the material of the anodic oxide film is that it adopts a honeycomb structure in which a plurality of micropores are formed in a direction substantially perpendicular to the substrate surface and in parallel at substantially equal intervals. In addition to this, the pore diameter, the pore interval, and the pore depth can be controlled relatively freely, which is a feature not found in other materials (see Non-Patent Document 3).

  As an application example of the anodized film, various devices such as a nano device, a magnetic device, and a light emitter are known. For example, in Patent Document 1, Co and Ni, which are magnetic metals, are filled in a micropore as a magnetic device, ZnO, which is a light emitting material, is filled in a micropore, and an enzyme / antibody is used as a biosensor in a micropore. Application examples such as filling inside are described.

Furthermore, in the field of biosensing, Patent Document 2 describes an example of using a structure in which a metal is filled in the micropores of an anodized film as a sample stage for Raman spectroscopic analysis.
Raman scattering is scattering in which energy is changed by causing an inelastic collision with particles when incident light (photons) hits the particles and scatters. Raman scattered light is used as a technique for spectroscopic analysis, but it is an issue to increase the intensity of scattered light used for measurement in order to improve the sensitivity and accuracy of analysis.
As a phenomenon that enhances the Raman scattered light, a surface-enhanced resonance Raman scattering (SERRS) phenomenon is known. This phenomenon is a phenomenon in which the scattering of certain molecules absorbed on the surface of metal electrodes, sols, crystals, deposited films, semiconductors, etc. is enhanced compared to that in solution, particularly with gold or silver, A remarkable enhancement effect of 10 ¹¹ to 10 ¹⁴ times is observed. Although the generation mechanism of the SERRS phenomenon has not been elucidated at present, it is considered that the above-described surface plasmon resonance has an influence. Patent Document 2 also aims to use the principle of plasmon resonance as means for enhancing the Raman scattering intensity.

In plasmon resonance, when the surface of a noble metal such as gold or silver is irradiated with light, the metal surface becomes an excited state, and the plasmon wave, which is a localized electron density wave, causes an interaction with an electromagnetic wave (resonance excitation). It is a phenomenon that forms a resonance state. Among them, surface plasmon resonance (SPR) is a surface plasmon wave generated when free electrons on a metal surface become excited when the metal surface is irradiated with light, and the free electrons vibrate in a collective manner. However, a strong electric field is generated.
In the region near the surface where plasmon resonance occurs, specifically, in the region within about 200 nm from the surface, an electric field enhancement of several orders of magnitude (in the example, 10 ⁸ to 10 ¹⁰ times) is observed. A marked uplift in the optical effect is observed. For example, when light is incident on a prism deposited with a thin film of gold or the like at an angle greater than the critical angle, a change in dielectric constant on the surface of the thin film can be detected with high sensitivity as a change in reflected light intensity due to a surface plasmon resonance phenomenon. .
Specifically, when an SPR device using the surface plasmon resonance phenomenon is used, measurement of the reaction amount and binding amount between biomolecules and kinetic analysis can be performed in real time without labeling. The SPR device is applied to the study of interactions between various substances such as immune responses, signal transduction, proteins, and nucleic acids, and recently, a paper on analyzing trace dioxins with the SPR device has been published (Non-patent Document 4). reference.).

Various methods have been studied as a method for increasing plasmon resonance. However, a technique for localizing plasmons by using metal as an isolated particle instead of a thin film is known. For example, Patent Document 2 described above describes a technique in which metal particles are provided on the pores of a regular anodic oxide film and localized.
Here, when using localized plasmon resonance due to metal particles, if the metal particles are in close proximity, the electric field strength is enhanced at the gap between the metal particles, and a state in which plasmon resonance is more likely to occur is realized. (See Non-Patent Document 5).

  In the method of producing an anodized film in which micropores are regularly arranged using self-ordering of the anodized film, conventionally, electrolysis is performed for a long time under specific electrolysis conditions, and the generation of micropores is regularly performed. After performing the regularization process, the anodic oxide film obtained in the regularization process is mixed with chromic acid and phosphoric acid in order to expose the vicinity of the bottoms of the most regularly aligned micropores on the surface. It is customary to perform a film removal step of dissolving in an aqueous solution.

Further, in Patent Document 3, an aluminum member or an alloy thereof is anodized to form a porous layer, and only the porous layer is peeled off from the base material using a reverse electrolysis means. The method of obtaining is described.
Non-Patent Document 6 describes a method in which a barrier layer is thinned by a current recovery method and then an anodized film is peeled off from an aluminum member using a reverse electrolysis means.

JP 2000-31462 A JP 2003-268592 A JP-A-61-88495 H. Masuda et. Al. , Jpn. J. et al. Appl. Phys. , Vol. 37 (1998), pp. L1340-1342, Part 2, No. 1 11A, 1 November 1998 (FIG. 2.) “Surface Technology Handbook”, Surface Technology Association (1998), Nikkan Kogyo Shimbun, p. 490-553 Hideki Masuda, “Highly Ordered Metal Nanohole Array Based on Anodized Alumina”, Solid State Physics, 1996, Vol. 31, No. 5, p. 493-499 Kanabe et al., ANALYTICA CHIMICA ACTA 2001, 434: 2: 223-230 Takayuki Okamoto, “Research on metal nanoparticle interactions and biosensors”, [on line], [searched on November 27, 2003], Internet <URL: http://www.plasmon.jp/reports/ okamoto.pdf> Journal of Aluminum Society, 1985, No. 7, Volume 201, p. 7-8

However, the film removal process using the mixed aqueous solution of chromic acid and phosphoric acid usually requires a long time of several hours to several tens of hours, although it varies depending on the thickness of the anodized film. Moreover, since the anodic oxide film is dissolved, it cannot be effectively used. In addition, it was necessary to use a chromic acid that is undesirable for the environment.
In addition, when the method of peeling the anodized film from the aluminum member using the reverse electrolysis means after reducing the film thickness by the current recovery method described in Patent Document 3 and Non-Patent Document 6, It was found that by the recovery method, the pores of the micropores were branched into fine pores, and the regularly arranged dents on the surface of the aluminum member obtained by peeling were disturbed. Therefore, for example, even if the obtained aluminum member was further anodized to form an anodized film, it could not be used for a sample table for Raman spectroscopic analysis.

Accordingly, the present invention is, without using the environmentally undesirable material such as chromic acid, in a short time, to provide a manufacturing how the structure can be obtained a structure having a recess in regular sequence Objective.

  As a result of diligent research to achieve the above object, the present inventor conducted electrolysis so that an electric current flows only on the surface of the anodized film using the aluminum member having the anodized film as a cathode, and in a short time. The present inventors have found that a structure having depressions of various arrangements can be obtained, and the present invention has been completed.

That is, the present invention provides the following (1) to (11).
(1) The aluminum member having an aluminum substrate and an anodized film present on the surface of the aluminum substrate is subjected to electrolysis as a cathode, whereby the anodized film and the aluminum substrate are separated to form an anodized film. A method for producing a structure comprising a peeling step for obtaining a structure,
In the peeling step, the electrolysis is performed so that a current flows on the surface of the anodized film.
(2) The method for manufacturing a structure according to (1), wherein in the peeling step, the electrolysis is performed so that a current flows only on a surface of the anodized film.
(3) In the peeling step, the electrolysis is performed in a state where the electrolytic solution is in contact with the surface of the anodized film and the electrolytic solution is not in contact with the side surface of the anodized film and the aluminum substrate. The manufacturing method of the structure of description.
(4) The manufacturing method of the structure according to any one of (1) to (3), wherein in the peeling step, the electrolysis is constant voltage electrolysis .
(5) The method for manufacturing a structure according to (4), wherein, in the peeling step, the electrolysis is terminated after a current value becomes 0.1 A / dm ² or less.

(6) By performing electrolysis using an aluminum member having an aluminum substrate and an anodized film present on the surface of the aluminum substrate as a cathode, the anodized film and the aluminum substrate are separated to have a plurality of depressions. A separation step of obtaining a structure comprising an aluminum substrate;
An anodizing treatment step of performing anodizing treatment on the aluminum substrate having the plurality of depressions to obtain an aluminum substrate having an anodized film having micropores on the surface. There,
In the peeling step, the electrolysis is performed so that a current flows on the surface of the anodized film.
(7) The method for manufacturing a structure according to (6), wherein, in the peeling step, the electrolysis is performed so that a current flows only on a surface of the anodized film.
(8) In the step (7), in the peeling step, the electrolysis is performed in a state where the electrolytic solution is in contact with the surface of the anodized film and the electrolytic solution is not in contact with the side surface of the anodized film and the aluminum substrate. The manufacturing method of the structure of description.
(9) The method for producing a structure according to any one of (6) to (8), wherein in the peeling step, the electrolysis is constant-voltage electrolysis .
(10) The method for manufacturing a structure according to (9), wherein, in the peeling step, the electrolysis is terminated after a current value becomes 0.1 A / dm ² or less.
( 11 ) Further, after the anodizing treatment step, the chemical dissolution treatment step of performing a chemical dissolution treatment on a structure composed of an aluminum substrate having the anodized film having the micropores on the surface is provided. ( 10 ) The manufacturing method of the structure in any one of .

  According to the structure manufacturing method of the present invention, a structure having regularly arranged depressions can be obtained in a short time.

The present invention is described in detail below.
According to a first aspect of the present invention, the anodized film and the aluminum substrate are separated by performing electrolysis using an aluminum member having an aluminum substrate and an anodized film present on the surface of the aluminum substrate as a cathode. A structure manufacturing method comprising a peeling step for obtaining a structure comprising an anodized film, wherein the electrolysis is performed so that a current flows only on the surface of the anodized film in the peeling step. It is a manufacturing method of a body.

<Aluminum member>
The aluminum member used in the present invention has an aluminum substrate and an anodized film present on the surface of the aluminum substrate. This aluminum member can be obtained by anodizing the surface of the aluminum substrate.

<Aluminum substrate>
The aluminum substrate is not particularly limited. For example, a commercially available aluminum substrate; a substrate obtained by depositing high-purity aluminum on low-purity aluminum (for example, recycled material); vapor deposition, sputtering, etc. on the surface of silicon wafer, quartz, glass, or the like A substrate coated with high-purity aluminum by the above method; a resin substrate laminated with aluminum.

  Of the aluminum substrate, the surface on which the anodized film is provided by anodizing treatment preferably has an aluminum purity of 99.5% by mass or more, more preferably 99.80% by mass or more, and 99.80% by mass. The amount is preferably less than 99% by mass, and more preferably 99.95% by mass or less. When the aluminum purity is 99.5% by mass or more, the regularity of the pore arrangement is sufficient, and when it is less than 99.99% by mass, it can be produced at low cost.

  The surface of the aluminum substrate is preferably subjected to degreasing and mirror finishing in advance.

<Degreasing treatment>
The degreasing treatment is performed for the purpose of dissolving and removing organic components (mainly fat content) and the like attached to the surface using an acid, an alkali, an organic solvent, or the like. A conventionally known degreasing agent can be used for the degreasing treatment.
Specifically, for example, various commercially available degreasing agents can be used by a predetermined method.
In addition, the aluminum substrate is placed in a sodium hydroxide aqueous solution having a pH of about 10 to 13 and a temperature of about 30 to 50 ° C., a sulfuric acid aqueous solution having a pH of about 1 to 4 and a temperature of about 40 to 70 ° C. It can also be done by soaking.
As a preferred degreasing treatment, there is exemplified a method in which an aluminum substrate is washed with acetone and then immersed in sulfuric acid having a pH of 4 and a temperature of 50 ° C. This method is preferable because fat on the surface of the aluminum is removed while aluminum hardly dissolves.

<Mirror finish processing>
The mirror finish process is performed to eliminate unevenness on the surface of the aluminum substrate and improve the uniformity and reproducibility of the sealing process by an electrodeposition method or the like.
In the present invention, the mirror finish is not particularly limited, and a conventionally known method can be used. Examples thereof include a method of polishing with various commercially available polishing cloths, a method of combining various commercially available abrasives (for example, diamond, alumina) and a buff, a method of performing electrolytic polishing, and a method of performing chemical polishing. These methods can be used in appropriate combination.
Methods of electrolytic polishing and chemical polishing are described in, for example, Aluminum Handbook (6th edition), Japan Aluminum Association (2001), p. Various methods described in 164 to 165 may be mentioned.
As a preferable mirror finishing treatment, a method using an abrasive is performed by changing the abrasive used from coarse particles to fine particles over time, and then performing electrolytic polishing. In this case, the final polishing agent is preferably # 1500. According to this method, when the aluminum substrate is manufactured through rolling, the rolling streaks can be eliminated even if rolling streaks are generated during rolling.
By mirror finishing, for example, a surface having an average surface roughness R _{a of} 0.03 μm or less and a glossiness of 70% or more can be obtained. The average surface roughness _Ra is preferably 0.02 μm or less. Further, the glossiness is preferably 80% or more.
The glossiness is a regular reflectance obtained in accordance with JIS Z8741-1997 “Method 3 60 ° Specular Gloss” in the direction perpendicular to the rolling direction.

<Anodizing treatment>
As the anodizing treatment, a conventionally known method can be used. Specifically, it is preferable to use the self-ordering method described later.
The self-ordering method is a method of improving the regularity by utilizing the property that the micropores of the anodized film are regularly arranged and removing the factors that disturb the regular arrangement. Specifically, high-purity aluminum is used, and an anodized film is formed at a low speed over a long period of time (for example, several hours to several tens of hours) at a voltage according to the type of the electrolytic solution.

As a representative example of the self-ordering method, J.A. Electrochem. Soc. Vol. 144, no. 5, May 1997, p. L128 (Non-Patent Document 7), Jpn. J. et al. Appl. Phys. Vol. 35 (1996) Pt. 2, no. 1B, L126 (Non-patent Document 8), Appl. Phys. Lett, Vol. 71, no. 19, 10 Nov 1997, p. 2771 (Non-Patent Document 9) and Non-Patent Document 1 are known.
The methods described in these known documents have a technical feature in that a high-purity material is used and a treatment is performed for a long time at a relatively low temperature with a specific voltage corresponding to the electrolytic solution. Specifically, all use materials having an aluminum purity of 99.99% by mass or more, and the self-ordering method is performed under the conditions shown below.

0.3 mol / L sulfuric acid, 0 ° C., 27 V, 450 minutes (non-patent document 7)
0.3 mol / L sulfuric acid, 10 ° C., 25 V, 750 minutes (non-patent document 7)
0.3 mol / L oxalic acid, 17 ° C., 40-60 V, 600 minutes (Non-patent Document 8)
0.04 mol / L oxalic acid, 3 ° C., 80 V, film thickness 3 μm (Non-patent Document 9)
0.3 mol / L phosphoric acid, 0 ° C., 195 V, 960 minutes (Non-patent Document 9)

  The self-ordered anodizing treatment used in the present invention may be, for example, a method of energizing an aluminum substrate as an anode in a solution having an acid concentration of 1 to 10% by mass. As the solution used for the anodizing treatment, oxalic acid, sulfuric acid, citric acid, malonic acid, tartaric acid, phosphoric acid and the like can be used alone or in combination of two or more.

The conditions of the self-ordering anodization treatment cannot be determined unconditionally because they vary depending on the electrolyte used, but generally the electrolyte concentration is 0.01 to 10 mol / L, the solution temperature is 0 to 20 ° C., It is preferable that the current density is 0.1 to 10 A / dm ² , the voltage is 15 to 240 V, the amount of electricity is 3 to 10,000 C / dm ² , and the electrolysis time is 30 to 1000 minutes.
The electrolysis is preferably constant voltage electrolysis.

The properties of the anodized film are as follows.
The thickness including the barrier layer is preferably 0.1 μm or more, and more preferably 1 μm or more. Within the above range, the regularity of the micropores becomes more excellent.
Moreover, it is preferable that thickness is 100 micrometers or less including a barrier layer. When it is in the above range, peeling from the aluminum substrate in the peeling step described later becomes easy.
The thickness of the barrier layer is preferably 600 nm or less, more preferably 5 to 400 nm, and still more preferably 10 to 80 nm. Within the above range, the peelability in the peeling step described later is excellent.

The pore diameter is 10 to 500 nm, preferably 15 to 100 nm, and more preferably 20 to 80 nm. Within the above range, the metal is more uniformly filled in the difference in filling the micropore with the metal.
The coefficient of variation of the pore diameter is not particularly limited, but is preferably less than 30%, more preferably 5 to 20%.
The coefficient of variation of pore diameter (CV: Coefficient of Variation) is an index of pore diameter variation and is defined by the following equation.

  (Variation coefficient of pore diameter) = (Standard deviation of pore diameter) / (Average of pore diameter)

The period of the micropores is preferably 20 to 700 nm, more preferably 25 to 600 μm, and further preferably 25 to 150 nm.
The coefficient of variation of the micropore cycle is not particularly limited, but is preferably less than 30%, more preferably 5% or more and less than 20%.
The area ratio occupied by the micropores is preferably 10 to 70%.

<Pore wide processing>
In the present invention, the above-described aluminum member may be one in which a pore-wide treatment has been applied to the anodized film.
The pore-wide treatment is a treatment for expanding the pore diameter of the micropore by dissolving the anodized film by immersing the aluminum substrate in an acid aqueous solution or an alkali aqueous solution after the anodizing treatment. Thereby, it becomes easy to control the regularity of the arrangement of the micropores.

When an aqueous acid solution is used for the pore wide treatment, it is preferable to use an aqueous solution of an inorganic acid such as sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, or a mixture thereof. The concentration of the acid aqueous solution is preferably 1 to 10% by mass. The temperature of the acid aqueous solution is preferably 25 to 40 ° C.
When an alkaline aqueous solution is used for the pore-wide treatment, it is preferable to use an aqueous solution of at least one alkali selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide. The concentration of the alkaline aqueous solution is preferably 0.1 to 5% by mass. The temperature of the alkaline aqueous solution is preferably 20 to 35 ° C.
Specifically, for example, 50 g / L, 40 ° C. phosphoric acid aqueous solution, 0.5 g / L, 30 ° C. sodium hydroxide aqueous solution or 0.5 g / L, 30 ° C. potassium hydroxide aqueous solution is preferably used. .
The immersion time in the acid aqueous solution or the alkali aqueous solution is preferably 8 to 60 minutes, more preferably 10 to 50 minutes, and further preferably 15 to 30 minutes.

<Barrier layer thinning process>
In the present invention, it is one of preferred embodiments that the above-described aluminum member is an aluminum member obtained by thinning the barrier layer of the anodized film. When the barrier layer is thinned, the peelability in the peeling process described later is excellent.
The present inventor, after anodizing, gradually reduces the voltage without abruptly changing it, that is, does not generate a current recovery period, and maintains the state where the current always flows. It has been found that the barrier layer of the anodized film can be made thin without impairing the regularity of the micropore arrangement of the anodized film by the lowering method. This is probably because no branching occurs because no current recovery period occurs.

Specifically, for example, when the anodizing voltage is 100 V or more, the rate of voltage drop is preferably 20 V / min or less, more preferably 10 V / min or less, and 5 V / min or less. Is more preferable.
The larger the current to be maintained, the better. Specifically, it is preferably at 10 .mu.A / cm ² or more, more preferably 30 .mu.A / cm ² or more, more preferably 50 .mu.A / cm ² or more.
If the current becomes too low, the regularity of the arrangement of micropores is disturbed. Therefore, when the current drops below 10 μA / cm ² at the above speed, the voltage drop is stopped once and the current is 10 μA / cm ² or more. It is preferable to continue the voltage drop after waiting for the flow.

<Other processing>
Further, other processes can be performed as necessary.
For example, when a structure obtained by the method for producing a structure of the present invention (hereinafter also referred to as “ structure of the present invention ” ) is used as a sample stage and an aqueous solution is to be dropped into a film shape, contact with water In order to reduce the corner, a hydrophilic treatment may be performed. The hydrophilic treatment can be performed by a conventionally known method.
In addition, when the structure of the present invention is used as a sample stage and a protein that is denatured or decomposed with an acid is targeted, the acid remaining on the aluminum surface is neutralized, which is used for anodizing treatment. Therefore, neutralization treatment may be performed. The neutralization treatment can be performed by a conventionally known method.

<Peeling process>
The peeling step is a step of obtaining a structure made of the anodized film by electrolyzing the aluminum member described above as a cathode, thereby separating the anodized film and the aluminum substrate. In the stripping step, electrolysis is performed using the aluminum member as a cathode. This is referred to as “reverse electrolysis” because the anodizing electrolysis is the reverse of using the aluminum member as the anode.

  In the peeling process, hydrogen is generated at the interface between the anodized film of the aluminum member and the aluminum substrate by this reverse electrolysis, and this hydrogen contacts the aluminum substrate of the barrier layer at the interface with the aluminum substrate of the anodized film. It is considered that a part of the portion is reduced and dissolved to form aluminum ions, so that the anodized film and the aluminum substrate are separated at the interface.

  In reverse electrolysis, the above-described aluminum member is used as a cathode, and electrolysis is performed so that a current flows through the surface of the anodized film. Thereby, peeling becomes easy.

Among them, it is preferable to perform electrolysis so that current flows only on the surface of the anodized film. That is, it is preferable to perform electrolysis so that current flows on the surface of the anodized film and current does not flow on the aluminum substrate of the aluminum member.
Specifically, for example, electrolysis is performed in a state where the electrolytic solution is in contact with the surface of the anodized film and the electrolytic solution is not in contact with the side surface of the anodized film and the aluminum substrate. The method for making such a state is not particularly limited. For example, a method in which only the surface of the anodized film is exposed using masking or a jig, and then the aluminum member is immersed in the electrolytic solution. The method of supplying only to the surface of an anodized film is mentioned.

The method using masking is performed by covering a portion other than the portion in contact with the electrolytic solution on the surface of the anodized film of the aluminum member with an insulating material.
The insulating material is not particularly limited, but a material having a volume resistivity of 10 ¹⁶ Ω · m or more at a temperature of 20 ° C. is preferable. Examples thereof include resins (natural resins and synthetic resins), rubber, ceramics (for example, glass), metal oxides, and mica.
Among these, a flexible synthetic resin is preferable. Examples of the synthetic resin include vinyl chloride, polycarbonate, acrylic, PET, epoxy, polyimide, polypropylene, polyester, polyethylene, saran, and polyvinylidene chloride.
An insulating tape (hereinafter referred to as “adhesive tape”) in which an adhesive is applied using these synthetic resins as a base material can also be suitably used. Examples of the adhesive tape include an epoxy film (for example, Super10 manufactured by 3M), a polyimide film (for example, 1205 manufactured by 3M), a PTFE film (for example, 62 manufactured by 3M), and a polyester film (for example, 3M). 56), plastic film tape (for example, 470 manufactured by Scotch), polyester film (for example, Elep Masking N-300 manufactured by Nitto Denko), polypropylene tape (for example, dumplon manufactured by Nitto Denko) Is mentioned.

The method of covering with an insulating material is not particularly limited. For example, when a resin is used, a method of applying a liquid resin (for example, an adhesive) and a method of applying an adhesive tape are exemplified. Moreover, for example, after sticking an adhesive tape on the back surface of the aluminum substrate, a liquid resin is applied to the side surfaces of the aluminum substrate and the anodized film.
Among these, a method of applying a resin tape coated with a pressure-sensitive adhesive is preferable in terms of insulation in an electrolytic solution, availability, and simplicity of the method.

The thickness of the insulating material in the covering portion is preferably 1 μm or more from the viewpoint of electrical insulation, and more preferably 10 to 200 μm from the viewpoint of handleability.
When applying a pressure-sensitive adhesive or an adhesive to the insulating material, the thickness thereof is preferably 10 to 100 μm from the viewpoint of uniformity of application and prevention of deformation after bonding.

As described above, masking is performed by covering a portion other than the portion in contact with the electrolytic solution on the surface of the anodized film of the aluminum member with an insulating material. Specifically, the side surface of the anodized film and the entire aluminum substrate are covered with an insulating material.
Here, a part of the anodized film can be coated. In this case, it is preferable that the opening remaining after covering a part of the anodized film is a circle, an ellipse, or a rectangle with rounded corners because peeling is easy. Among these, a circular shape is preferable in that reverse electrolysis can be uniformly performed over the entire surface of the portion where reverse electrolysis is performed.

  The method using a jig is not particularly limited as long as it uses a jig that exposes only the surface of the anodized film.

  The anode used for reverse electrolysis is not particularly limited, and examples thereof include a Pt-plated Ti electrode, a Pt electrode, and a carbon electrode.

The electrolytic solution used for reverse electrolysis is not particularly limited, but is preferably an acid aqueous solution.
The aqueous acid solution preferably has a pH of 1 to 7, more preferably a pH of 2 to 6, and even more preferably a pH of 2.5 to 5.5. Moreover, it is preferable that it is 0.01-100 mS / cm, and, as for the electrical conductivity of acid aqueous solution, it is more preferable that it is 0.1-50 mS / cm.
When the pH and electric conductivity of the acid aqueous solution are within the above ranges, corrosion of the aluminum substrate and residual film are less likely to occur, and the peelability is improved.
If the electric conductivity of the acid aqueous solution is too low, a minimum current value may not be generated. In that case, it is preferable to increase the ion concentration in the acid aqueous solution to generate a minimum current value. On the contrary, if the ion concentration in the acid aqueous solution is too high, a minimum value of the current value is generated, but it is completed in a short time, and then the current value rapidly increases, so that control becomes difficult. Furthermore, if the time to reach the minimum value is exceeded, corrosion will occur.

In the acid aqueous solution, for example, oxalic acid, sulfuric acid, and phosphoric acid can be suitably used as the acid.
Further, for example, a metal salt compound that shows acidity when dissolved in water, or an organic compound that shows acidity when dissolved in water can be used.
Examples of the metal salt compound that dissolves in water and exhibits acidity include aluminum oxalate, aluminum sulfate, aluminum lactate, aluminum fluoride, and aluminum borate.
The organic compound that is acidic when dissolved in water is preferably a carboxylic acid. For example, saturated aliphatic dicarboxylic acids such as adipic acid, unsaturated aliphatic dicarboxylic acids such as maleic acid, aromatic monocarboxylic acids such as benzoic acid, aromatic dicarboxylic acids such as phthalic acid, and aromatic oxycarboxylic acids such as salicylic acid Are preferable.
In addition, a salt that is neutral when dissolved in water, that is, a neutral salt, can also be used. Suitable examples of the neutral salt include carbonates such as ammonium carbonate and borates such as ammonium borate.
In the case where a neutral salt is used, it is also a preferred embodiment to use a mixed bath to which a fluoride, a carbonic acid derivative or an acid amide is added as an additive. Examples of the fluoride include ammonium fluoride. Examples of the carbonic acid derivative include guanidine carbonate, urea, and formaldehyde. Examples of the acid amide include acetamide.
Among these, oxalic acid, aluminum oxalate, sulfuric acid, aluminum sulfate or a mixture thereof is preferable. In particular, aluminum sulfate and sulfuric acid are preferable in terms of availability and waste liquid treatment.

  Moreover, it is one of the preferable aspects to use the same kind as the electrolyte solution used by the said anodizing process.

The reverse electrolysis conditions vary depending on the electrolyte used, and therefore cannot be determined unconditionally.
For example, the concentration of the electrolytic solution is preferably 0.4 to 10% in the case of an oxalic acid aqueous solution, 2 to 20% in the case of an aqueous sulfuric acid solution, and 0.4 to 5% in the case of an aqueous phosphoric acid solution.
In general, the temperature of the electrolytic solution is preferably 0 to 50 ° C, and more preferably 10 to 35 ° C.
Current density is preferably 1~400mA / dm ^2, more preferably from 5~400mA / dm ^2, and even more preferably 10~300mA / dm ^2. When it is within the above range, unevenness does not occur in peeling, and it can be performed more uniformly.
The voltage is preferably 5 to 350V, more preferably 8 to 300V, and still more preferably 10 to 240V. The voltage is preferably lower than the electrolysis voltage when forming the anodized film.
Moreover, it is one of the preferable embodiments that the voltage is constant, and it is also one preferable embodiment that the voltage is increased with time.

In the present invention, the electrolysis is preferably terminated after the time when the current value becomes 0.1 A / dm ² or less.
FIG. 1 is a schematic graph showing a change in current over time when an aluminum member having an aluminum substrate and an anodized film is used as a cathode and electrolysis is performed so that the current flows only on the surface of the anodized film. .
There is a time point (T ₂ ) at which the current value becomes maximum immediately after the start of electrolysis (T ₁ ) to T ₃ . Since gas generation is observed between T _{1 and} T ₃ , it is assumed that H ⁺ generated at the interface between the barrier layer of the anodized film and the aluminum substrate becomes hydrogen molecules due to an electrochemical reaction. .
Thereafter, at T ₄ , the current rapidly decreases. At this point, it is considered that peeling between the anodized film and the aluminum substrate has been completed. Thereafter, until T ₅ remains low current value. It is estimated that hydrogen gas is accumulated between the anodic oxide film and the aluminum substrate between T _{4 and} T ₅ .
If reverse electrolysis is further continued, the current value once peaks at T ₆ . This is presumably because cracks occurred in the anodized film.
Thereafter, after T ₇ , it is presumed that the electrolytic solution penetrates between the anodized film and the aluminum substrate through cracking of the anodized film, and corrosion progresses.

In the present invention, the electrolysis is preferably terminated between T _{4 and} T ₅ . Thereby, it is possible to prevent corrosion due to cracking of the anodized film and penetration of the electrolytic solution. For this purpose, it is preferable to monitor the current value and terminate the electrolysis after the time when the current value becomes 0.1 A / dm ² or less.
The current value between T _{4 and} T ₅ is usually 30% or less, and most is 10% or less with respect to the maximum value (time point T ₂ ). Therefore, it is one of preferred embodiments that the current value is monitored and the electrolysis is terminated after the current value becomes 30% or less or 10% or less of the maximum value.

The aluminum substrate is exposed on the back and side surfaces (edges) of the aluminum substrate. If masking is not performed, current concentrates on the metal aluminum, making it difficult for the current to flow through the anodized film. Or the uniformity of the peeling surface is deteriorated.
Further, if masking or the like is not performed, the current flowing through the metal aluminum becomes a large part, so that it is difficult to grasp the peeling state of the anodized film from the change in the current value. As described above, by covering all of the side surfaces of the anodized film and the aluminum substrate with the insulating material, it is possible to grasp the peeling state of the anodized film from the change in the current value.

  After the electrolysis is completed, for example, the separated anodized film can be separated from the aluminum substrate by cutting the boundary between the portion where current is passed and the portion where current is not passed. At this time, it can be taken out after being fixed with an adhesive tape or the like so that the anodized film is not broken by the stress at the time of cutting.

In the aluminum substrate obtained by performing the peeling step, a residue of an anodic oxide film having a thickness of 0.2 μm or less may remain in a region of 10% or less of the peeling surface. When this aluminum substrate is used, it is preferable that no anodized film remains.
Therefore, in this case, it is preferable to perform chemical treatment after reverse electrolysis to remove the residue of the anodized film. Specifically, it can be removed by chemical treatment (chemical polishing treatment) such as a method of bringing various acidic or alkaline aqueous solutions into contact with the anodized film. The method of chemical treatment (chemical polishing treatment) is not particularly limited, and can be performed by, for example, a conventionally known method.

Examples of the acidic aqueous solution include a phosphoric acid aqueous solution, a sulfuric acid aqueous solution, a nitric acid aqueous solution, an oxalic acid aqueous solution, and a mixed aqueous solution of chromic acid and phosphoric acid. Among these, a mixed aqueous solution of chromic acid and phosphoric acid is preferable.
The acidic aqueous solution preferably has a pH of -0.3 to 6, more preferably a pH of 0 to 4, and still more preferably a pH of 2 to 4.
It is preferable that the temperature of acidic aqueous solution is 20-60 degreeC, and it is more preferable that it is 30-50 degreeC.
The treatment time is preferably 1 second to 6 hours, more preferably 5 seconds to 3 hours, and even more preferably 10 seconds to 1 hour.

Examples of the alkaline aqueous solution include aqueous solutions of sodium hydroxide, sodium carbonate, and potassium hydroxide.
The alkaline aqueous solution preferably has a pH of 10 to 13.5, more preferably a pH of 11 to 13.
The temperature of the alkaline aqueous solution is preferably 10 to 50 ° C, and more preferably 20 to 40 ° C.
The treatment time is preferably 1 second to 10 minutes, more preferably 2 seconds to 1 minute, and even more preferably 3 seconds to 30 seconds.

Moreover, these methods can also be combined. For example, the surface of the aluminum substrate is slightly dissolved with an alkaline aqueous solution to remove the anodized film residue, and then the neutralized product generated by the alkaline treatment is dissolved and removed with an acidic aqueous solution. The method of performing the desmut process to perform is mentioned.
Specifically, for example, after performing an alkali treatment that is brought into contact with a 5% by mass sodium hydroxide aqueous solution (temperature 70 ° C.) for 10 seconds, a desmut treatment that is brought into contact with a 30% by mass sulfuric acid aqueous solution (temperature 50 ° C.) for 60 seconds is performed. A method is mentioned.

  In addition, for example, “Aluminum Technical Handbook”, edited by the Japan Institute of Light Metals (1996), Karos Publishing, p. Various methods described as chemical pretreatment in 926-929 (Non-patent Document 10) can be mentioned. Among them, there are alkali degreasing, acid degreasing, electrolytic degreasing, and a combination thereof, which have an action of dissolving the surface layer of the aluminum substrate; alkaline etching treatment, acid etching treatment, and a combination of these having a strong action of dissolving the surface layer of the aluminum substrate. Preferably mentioned.

Further, when a part of the anodic oxide film remains even after the peeling process, the remaining anodic oxide film can be completely removed by repeating the anodic oxidation treatment and the peeling process a plurality of times alternately. .
When the anodized film is peeled off by this method, current recovery is not performed, and the regularity of the arrangement of the depressions on the aluminum substrate side is not disturbed. Therefore, this method is suitable in the second aspect of the present invention described later. .

Examples of suitable conditions for reverse electrolysis are illustrated below.
<Preferred condition 1>
Cathode: Anodized film obtained by anodizing with an oxalic acid aqueous solution with a concentration of 0.3 mol / L and a temperature of 17 ° C. under conditions of a voltage of 40 V and a treatment time of 60 minutes, thickness 60 μm
Anode: Carbon electrode Electrolyte: Concentration 0.04 g / L (in terms of aluminum ion), pH 3.8, electric conductivity 0.6 mS / cm, temperature 33 ° C. Aluminum sulfate aqueous solution Voltage: 40 V (set voltage)

In the first aspect of the present invention, the treatment time of the peeling step is extremely short compared to the time required for the film removal step of dissolving with a conventional mixed aqueous solution of chromic acid and phosphoric acid. Therefore, according to the first aspect of the present invention, an efficient structure can be manufactured.
Furthermore, the mixed aqueous solution of chromic acid and phosphoric acid has a rapid deterioration of the dissolving ability when the aluminum oxide content exceeds 15 g / L as Al ₂ O ₃ during the film removal step. It needs to be replaced. Since the anodic oxide film used in the present invention is generally thick, the amount of aluminum oxide eluted in a single treatment is large and the treatment liquid is severely deteriorated.
On the other hand, in the present invention, since the anodized film is peeled off in a solid state at the interface with the aluminum substrate, it can be easily separated with a filter or the like, and the acid aqueous solution used for reverse electrolysis does not deteriorate.
Therefore, the treatment time of the peeling step and the consumption amount of the acid aqueous solution in the present invention are much shorter than the treatment time of the film removal step and the consumption amount of the treatment solution by the conventional mixed aqueous solution of chromic acid and phosphoric acid, Few.

In the peeling step, the barrier layer is dissolved by the reverse electrolysis described above, and a structure made of an anodized film is obtained.
On the other hand, the aluminum substrate from which the anodized film has been peeled becomes an aluminum substrate having a plurality of depressions. The aluminum substrate having the plurality of depressions is used in a second aspect of the present invention described later. Hereinafter, it demonstrates concretely using drawing.

FIG. 2 is an explanatory view of the structure manufacturing method of the present invention.
FIG. 2A is a schematic cross-sectional view of the aluminum member before the peeling step. As shown in FIG. 2A, the aluminum member 10 has an aluminum substrate 12 and an anodized film 14 present on the surface of the aluminum substrate 12. In the anodic oxide film 14, micropores 16 are present, and a lower part thereof is a barrier layer 18.
FIG. 2B and FIG. 2C are schematic cross-sectional views of the structure and the aluminum substrate obtained by the peeling process, respectively.
A structure 20 shown in FIG. 2B is obtained by dissolving the barrier layer 18 of the anodized film 14 of the aluminum member 10 shown in FIG. 2A and is formed from an anodized film having a plurality of depressions 22. Become.
An aluminum substrate 24 shown in FIG. 2C is obtained by dissolving the barrier layer 18 of the anodized film 14 of the aluminum member 10 shown in FIG. 2A and has a plurality of depressions 26.

  According to a second aspect of the present invention, the anodized film and the aluminum substrate are separated by performing electrolysis using an aluminum member having an aluminum substrate and an anodized film present on the surface of the aluminum substrate as a cathode. A peeling step for obtaining a structure composed of an aluminum substrate having a plurality of depressions, and a structure comprising an aluminum substrate having an anodized film having micropores on the surface by anodizing the aluminum substrate having the plurality of depressions A method for producing a structure, comprising: an anodizing treatment step for obtaining a body, wherein in the peeling step, the electrolysis is performed so that a current flows only on a surface of the anodized film. It is.

  The peeling step of the second aspect of the present invention is performed in the same manner as the peeling step of the first aspect of the present invention.

<Anodizing process>
In the second aspect of the present invention, an anodizing treatment step is performed after the peeling step.
The anodizing treatment step is a step of obtaining an aluminum substrate having an anodized film having micropores on the surface thereof by anodizing the aluminum substrate having a plurality of depressions obtained in the peeling step.

  In the aluminum substrate having a plurality of depressions obtained in the peeling step, the shape of the bottom part of the barrier layer of the micropores that are most regularly aligned is a depression on the surface (see FIG. 2C). ). Therefore, the depressions on the surface are almost hemispherical and are regularly aligned like micropores.

A conventionally well-known method can be used for an anodizing process process. Specifically, it is the same as the anodizing treatment for obtaining the aluminum member described above.
Here, it is one of the preferable embodiments to use the same type of electrolyte as that used in the reverse electrolysis. Thereby, it becomes possible to perform reverse electrolysis and an anodizing process in the same electrolytic cell. Moreover, even if it is a case where it carries out by another electrolytic cell, there is no bad influence by carrying in of the liquid to an anodizing treatment tank.

In this anodizing treatment step, a plurality of regularly arranged depressions on the surface of the aluminum substrate are used as starting points for the anodizing treatment to form an anodized film having regularly arranged micropores.
Therefore, a structure comprising an aluminum substrate having an anodized film having regularly arranged micropores on the surface is obtained by the anodizing treatment step.

  FIG. 2D is a schematic cross-sectional view of a structure obtained by an anodizing process. The structure 28 shown in FIG. 2D is obtained by forming the anodized film 30 by subjecting the aluminum substrate 24 shown in FIG. At the time of anodizing, micropores 32 are formed starting from the depression 26 of the aluminum substrate 24. Therefore, the structure 28 is made of the aluminum substrate 34 having the anodic oxide film 30 having the micropores 32 on the surface.

  In the second aspect of the present invention, the treatment time of the peeling step is extremely short compared to the time required for the conventional film removal step of dissolving with a mixed aqueous solution of chromic acid and phosphoric acid. Therefore, according to the 2nd aspect of this invention, manufacture of an efficient structure is attained.

<Chemical dissolution treatment process>
In the second aspect of the present invention, there is further provided a chemical dissolution treatment step of subjecting a structure comprising an aluminum substrate having an anodized film having micropores to a chemical dissolution treatment after the anodization treatment step. It is one of the preferable embodiments. By performing the chemical dissolution treatment step, the pore diameter becomes more uniform.
The chemical dissolution treatment can be performed by the same method as the pore wide treatment described above.

<Structure>
The structure composed of the anodized film obtained by the first aspect of the present invention and the structure composed of the aluminum substrate having the micropores having the micropores obtained by the second aspect of the present invention are both regular. Since it has a plurality of depressions and micropores having a typical arrangement, it can be applied to various applications.

For example, it can be used as a sample table for Raman spectroscopic analysis by filling a plurality of depressions or micropores with metal by a sealing treatment.
It can also be used as a nanoprint mold.
Furthermore, the structure comprising the anodized film obtained by the first aspect of the present invention can be used as a separation filter.

<Sealing treatment>
The metal used for the sealing treatment is an element composed of a metal bond having free electrons, and is not particularly limited, but is preferably a metal in which plasmon resonance has been confirmed. Among these, gold, silver, copper, nickel, and platinum are known to cause plasmon resonance (Hyundai Kagaku, September 2003, p. 20 to 27 (Non-patent Document 11)), and are preferable. In particular, gold and silver are preferable because electrodeposition and colloidal particle preparation are easy.

The method for the sealing treatment is not particularly limited, and a conventionally known method can be used.
For example, an electrodeposition method; a method in which a dispersion of colloidal metal particles is applied to the structure of the present invention and dried is preferably mentioned. The metal is preferably a single particle or an aggregate.
As the electrodeposition method, a conventionally known method can be used. Specifically, for example, in the case of gold electrodeposition, an aluminum member is immersed in a dispersion at 30 ° C. containing 1 g / L HAuCl ₄ and 7 g / L H ₂ SO _4, and a constant voltage of 11 V ( (Adjusted with slidac), and a method of electrodeposition treatment for 5 to 6 minutes.
As the electrodeposition method, Hyundai Kagaku, January 1997, p. An example using copper, tin and nickel is described in detail in 51-54 (Non-patent Document 12), and this method can also be used.

The dispersion used in the method using metal colloidal particles can be obtained by a conventionally known method. For example, it can be obtained by a method for producing fine particles by a low vacuum evaporation method or a method for producing a metal colloid that reduces an aqueous solution of a metal salt.
The metal colloidal particles preferably have an average particle size of 1 to 200 nm, more preferably 1 to 100 nm, and even more preferably 2 to 80 nm.
As the dispersion medium used in the dispersion, water is preferably used. In addition, solvents that can be mixed with water, for example, alcohols such as ethyl alcohol, n-propyl alcohol, i-propyl alcohol, 1-butyl alcohol, 2-butyl alcohol, t-butyl alcohol, methyl cellosolve, and butyl cellosolve A mixed solvent with water can also be used.

  In the method using metal colloidal particles, the coating method is not particularly limited, and examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

As the dispersion liquid used in the method using metal colloid particles, for example, a gold colloid particle dispersion liquid and a silver colloid particle dispersion liquid are preferably used.
As the dispersion of colloidal gold particles, for example, those described in JP-A-2001-89140 and JP-A-11-80647 can be used. Commercial products can also be used.
The dispersion of silver colloidal particles preferably contains silver and palladium alloy particles in that they are not affected by the acid eluted from the anodized film. In this case, the palladium content is preferably 5 to 30% by mass.

  After applying the dispersion, it is appropriately washed with a solvent such as water. Thereby, only the particles filled in the plurality of depressions or micropores remain, and the particles not filled in the plurality of depressions or micropores are removed.

It is preferable that the adhesion amount of the metal after the sealing treatment is 100 to 500 mg / m ² .
The surface porosity after the sealing treatment is preferably 20% or less. The surface porosity after the sealing treatment is a ratio of the total area of the plurality of dents or micropore openings that are not sealed to the area of the structure surface. When the surface porosity is within the above range, stronger localized plasmon resonance is obtained.

  When the pore diameter is 50 nm or more, a method using metal colloidal particles is preferably used. Moreover, when a pore diameter is less than 50 nm, an electrodeposition method is used suitably. A method of combining both is also preferably used.

In the structure after the sealing treatment, the metal seals the plurality of depressions or micropores, and is present as particles on the surface of the structure.
In general, the interval between the metal particles is preferably shorter in order to increase the Raman enhancement effect, but the optimum interval is affected by the size and shape of the metal particles. In addition, depending on the molecular weight of the substance used as the specimen for Raman spectroscopic analysis and the viscosity of the liquid, there may be a problem that it does not enter between the metal particles.
Therefore, although the interval between the metal particles cannot be determined unconditionally, it is generally preferably in the range of 1 to 400 nm, more preferably 5 to 300 nm, and still more preferably 10 to 200 nm. Within the above range, the Raman enhancement effect is increased, and the problem that the substance to be detected does not enter between the metal particles is reduced.
Here, the “interval between metal particles” is the shortest distance between the surfaces of adjacent particles.

<Raman enhancement effect by localized plasmon resonance>
The Raman enhancement effect is a phenomenon in which the Raman scattering intensity of the molecules adsorbed on the metal is enhanced by about 10 ⁵ to 10 ⁶ times, and is called surface enhanced Raman scattering (SERS: Surface Enhanced Raman Scattering). And the said nonpatent literature 11 describes that the Raman enhancement effect is acquired by the localized plasmon resonance using metal particles, such as gold | metal | money, silver, copper, platinum, nickel.
Since the structure after the sealing treatment can generate localized plasmon resonance having a higher intensity than that of the prior art, a stronger Raman enhancement effect can be obtained when used for Raman spectroscopic analysis. Therefore, the sample stand for Raman spectroscopic analysis using the structure after the sealing treatment is useful.
The method for using the sample stage for Raman spectroscopic analysis using the structure after the sealing treatment is the same as the method for using the conventional sample stage for Raman spectroscopic analysis. Specifically, the sample stage for Raman spectroscopic analysis using the structure after sealing treatment is irradiated with light, and the Raman scattering intensity of the reflected light or transmitted light is measured. Detect the properties of the material in the vicinity of the retained metal.

<Nanoprint>
The structure of the present invention can be used as a nanoprint mold. Specifically, a substrate having a plurality of protrusions can be obtained by pouring a resin or the like into a plurality of depressions or micropores of the structure of the present invention and hardening. The substrate having the plurality of protrusions can be used for an optical device, for example.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these.
1. Fabrication of structures (Examples 1 to 15 and Comparative Example 1)
The substrate was sequentially subjected to mirror finish, self-ordered anodizing, masking and reverse electrolysis to obtain a structure made of an anodized film and an aluminum substrate. The obtained aluminum substrate was sequentially subjected to the present anodizing treatment and pore wide treatment to obtain a structure made of an aluminum substrate.
Details of each process will be described below.

(1) Substrate For manufacturing the structure, the following substrate 1 was used.
Substrate 1: High-purity aluminum, manufactured by Wako Pure Chemical Industries, Ltd., purity 99.99 mass%, thickness 0.4 mm

(2) Mirror finish treatment The following mirror finish treatment was performed on the substrate.
<Mirror finish processing>
A mirror finish was applied by electrolytic polishing. The electrolytic polishing was performed for 5 minutes at a constant current of 12.5 A / dm ² using an electrolytic solution (temperature: 65 ° C.) having the following composition, using the anode as a substrate and the cathode as a carbon electrode.

<Electrolyte composition>
・ 85 mass% phosphoric acid (Wako Pure Chemical Industries, Ltd.) 1320mL
・ 600% 50% sulfuric acid aqueous solution
・ Pure water 20mL

(3) Self-ordered anodizing treatment (formation of dents)
The surface of the mirror-finished substrate was subjected to self-ordering anodizing treatment under any of the following conditions A and B to form a recess. This depression became a starting point for forming micropores in the anodizing process described later.

<Self-ordered anodizing treatment>
<Condition A>
A sulfuric acid aqueous solution having a concentration of 0.3 mol / L and a temperature of 16 ° C. was prepared using sulfuric acid (a reagent manufactured by Kanto Chemical Co., Inc.). A substrate (treatment region 5 cm × 10 cm) was immersed in this sulfuric acid aqueous solution, and self-ordered anodizing treatment was performed for 7 hours under a constant voltage condition of 25 V to form an anodized film having a thickness of 90 μm on the substrate. .
In the self-ordering anodizing treatment, SUS304 electrode as a cathode, NeoCool BD36 (manufactured by Yamato Kagaku Co.) as a cooling device, a pair stirrer PS-100 (manufactured by EYELA) as a stirring and heating device, and GP0650-2R (Takasago Seisakusho) as a power source Used). A PET tape (Damplon tape, manufactured by Nitto Denko) was previously applied to the surface of the substrate not facing the electrode surface so as not to be anodized.

<Condition B>
An oxalic acid aqueous solution having a concentration of 0.5 mol / L and a temperature of 16 ° C. was prepared using oxalic acid dihydrate (a reagent manufactured by Kanto Chemical Co., Inc.). The substrate (treatment region 5 cm × 10 cm) was immersed in this sulfuric acid aqueous solution, and self-ordered anodizing treatment was performed for 5 hours under a constant voltage condition of 40 V to form an anodic oxide film having a film thickness of 45 μm on the substrate. .
In the self-ordering anodizing treatment, SUS304 electrode as a cathode, NeoCool BD36 (manufactured by Yamato Kagaku Co.) as a cooling device, a pair stirrer PS-100 (manufactured by EYELA) as a stirring and heating device, and GP0650-2R (Takasago Seisakusho) as a power source Used). A PET tape (Damplon tape, manufactured by Nitto Denko) was previously applied to the surface of the substrate not facing the electrode surface so as not to be anodized.

<Thickness measurement method>
The substrate on which the anodized film is formed is bent, and the side surface (fracture surface) of the cracked portion is used with an ultra-high resolution SEM (Hitachi S-900, manufactured by Hitachi, Ltd.) at an acceleration voltage of 20 V and a magnification of 200. The film thickness was measured. Ten locations were randomly extracted at one time, and the average value was obtained as the film thickness. The film thickness values at 10 locations were all within a range of ± 10% of the average value.

(4) Masking Masking was performed on the substrate subjected to the self-ordering anodizing treatment. The masking method is shown in Table 1. The meanings of the notations in Table 1 are as follows.
“None”: After self-ordering anodizing treatment, the PET tape was peeled off and subjected to reverse electrolysis without masking.
“Back side”: After the self-ordering anodizing treatment, the PET tape was left as it was and subjected to reverse electrolysis.
"Back side + edge": After self-ordering anodization, leave the PET tape as it is, and then apply a two-component mixed epoxy resin (Araldite, manufactured by Nichiban Co., Ltd.) to the edge of the substrate, Then, the resin was cured and then subjected to reverse electrolysis.

“Back side + Edge + Surface A”: After the above processing of “Back side + Edge”, PET tape having a circular opening with a radius of 1.7 cm on the surface on the anodized film side (Damplon tape, manufactured by Nitto Denko) ) Was pasted. The PET tape was affixed so that the opening was positioned substantially in the center of the substrate and the cured resin at the edge of the substrate was also covered.
“Back side + Edge + Surface B”: After the treatment of “Back side + Edge”, a PET tape having an elliptical opening with a major axis of 2.5 cm and a minor axis of 1.4 cm on the surface on the anodized film side ( Damplon tape, manufactured by Nitto Denko) was attached. The PET tape was affixed so that the opening was positioned substantially in the center of the substrate and the cured resin at the edge of the substrate was also covered.
“Back side + Edge + Surface C”: After the above processing of “Back side + Edge”, the surface on the anodized film side has an opening in the form of a round with a radius of 5 mm in the vicinity of the apex of a 3 cm piece. A PET tape (Damplon tape, manufactured by Nitto Denko) was attached. The PET tape was affixed so that the opening was positioned substantially in the center of the substrate and the cured resin at the edge of the substrate was also covered.
“Back side + Edge + Surface D”: After the above processing of “Back side + Edge”, a PET tape having a 3 cm square opening on the surface on the anodized film side (Damplon tape, manufactured by Nitto Denko) Pasted. The PET tape was affixed so that the opening was positioned substantially in the center of the substrate and the cured resin at the edge of the substrate was also covered.

  “Special jig”: As shown in FIG. 3, a special jig is disposed on the anodized film 14 side of the aluminum substrate 12 (aluminum member 10) on which the anodized film 14 is formed, and is used for reverse electrolysis. did. The special jig had a cathode 40, a packing 42 having the cathode 40 in the internal space, an electrolyte inlet 44 provided in the packing, and an electrolyte outlet 46. The cathode 40 was 3 cm in diameter. The inner space of the packing 42 was 3 cm in diameter and 2 cm in depth. The electrolyte solution outlet 46 was provided with a check valve that also served as a pressure valve (not shown). During reverse electrolysis, the electrolyte (shown by hatching) flows into the inner space of the packing 42 through the electrolyte inlet 44, and the electrolyte flows out from the inner space 42 of the packing through the electrolyte outlet 46. In addition, the end portion of the packing 42 and the anodized film 14 are in close contact with each other when the packing 42 is pressed against the anodized film 14 so that the electrolyte does not leak. FIG. 3 is a schematic explanatory view of a special jig used for reverse electrolysis, and the size of the micropore 16 with respect to the size of the special jig is different from the actual one.

(5) Reverse electrolysis After performing masking, using the substrate on which the above-described anodized film is formed as a cathode, using a Pt electrode as an anode, in an aluminum sulfate aqueous solution having a concentration of 4.5 g / L and a temperature of 33 ° C. Reverse electrolysis was performed under a constant voltage condition of a voltage of 16 V to separate the anodized film from the aluminum substrate. The substrate on which the anodized film was formed was placed in an aluminum sulfate aqueous solution so that the surface direction of the substrate was vertical.
In reverse electrolysis, the current value was monitored. Table 1 shows the maximum current value, the current value at the end of reverse electrolysis, and the current ratio (current value at the end of reverse electrolysis / maximum value of current value).
In Example 15, reverse electrolysis was performed by gradually increasing the voltage from 0 V to 17.8 V at a rate of increase of 2 V / min instead of a constant voltage condition (current value in Table 1). The maximum value and current ratio are not shown.)
After reverse electrolysis, a PET tape (Damplon tape, manufactured by Nitto Denko) is pasted on the surface of the anodized film, and then cut with a cutter at the boundary between the part that was in contact with the electrolyte and the part that was not in contact in reverse electrolysis The anodized film was separated from the aluminum substrate.

(6) Main anodizing treatment The main anodizing treatment was performed on the aluminum substrate obtained by peeling off the anodized film by reverse electrolysis. This anodizing treatment was performed under the same conditions A or B as those used in the self-ordering anodizing treatment except that the treatment time was 2 minutes.

(7) Pore-wide treatment The aluminum substrate after this anodizing treatment was subjected to a pore-wide treatment in order to improve the uniformity of the sealing treatment described later. The pore-wide treatment was performed by immersing the aluminum substrate in a phosphoric acid aqueous solution (temperature 30 ° C.) having a concentration of 5 mass% for 15 minutes.

2. Evaluation of peeled state The peeled state between the anodized film after reverse electrolysis and the aluminum substrate in each of the above examples was evaluated.
Specifically, for the peeled surface of the aluminum substrate after reverse electrolysis, by visually painting a white dull part without specular gloss with a pen and analyzing the image, the area ratio of the specular gloss part is calculated, This evaluated the uniformity of peeling.
The results are shown in Table 1. In the table, regarding "uniformity of peeling", the area ratio of the part having the specular gloss is 95% to 100% or less, A is 90% to 95% or less B, 85% Over 90% and below, C, over 80% over 85% D, over 70% over 80% E, over 70% under F. Indicated.

3. Evaluation of structure comprising aluminum substrate The degree of ordering, which is an index of the regularity of the micropores, was determined for the aluminum substrate after this anodizing treatment. The results are shown in Table 1.

  The degree of ordering is defined by the following formula (1).

  Ordering degree (%) = B / A × 100 (1)

  Here, in the above formula (1), A represents the total number of micropores in the measurement range. B, when a circle with the shortest radius is drawn centering on the center (center of gravity) of one micropore and inscribed in the edge of another micropore, a micropore other than the one micropore is inside the circle. This represents the number of the one micropore in the measurement range that includes 6 centers (centers of gravity).

FIG. 4 is an explanatory diagram of a method for calculating the degree of ordering of pores. The above formula (1) will be described more specifically with reference to FIG.
The micropore 1 shown in FIG. 4A is centered on the center (center of gravity) of the micropore 1 and is inscribed in the circle 3 having the shortest radius inscribed in the edge of the other micropore (inscribed in the micropore 2). ), The center (center of gravity) of the micropores other than the micropore 1 is included inside the circle 3. Therefore, the micropore 1 is included in B.
The micropore 4 shown in FIG. 4B is centered on the center (center of gravity) of the micropore 4 and is inscribed in the circle 6 having the shortest radius inscribed in the edge of the other micropore (the micropore 5 is inscribed). ) Includes five centers (centroids) of micropores other than the micropores 4 inside the circle 6. Therefore, the micropore 4 is not included in B. The micropore 7 shown in FIG. 4B is a circle 9 (inscribed in the micropore 8 inscribed in the shortest radius) centered on the center (center of gravity) of the micropore 7 and inscribed in the edge of another micropore. ) Is drawn, the center (center of gravity) of the micropores other than the micropores 7 is included inside the circle 9. Therefore, the micropore 7 is not included in B.

As is apparent from Table 1, the structure production methods (Examples 1 to 15) of the present invention are excellent in the uniformity of peeling and the regularity of the pores of the structure composed of the obtained aluminum substrate.
On the other hand, when reverse electrolysis was performed so that a current flowed through the aluminum substrate (Comparative Example 1), the uniformity of peeling was poor.

It is a typical graph which shows the time-dependent change of the electric current at the time of performing electrolysis so that an electric current may flow only through the surface of an anodized film by using an aluminum member having an aluminum substrate and an anodized film as a cathode. It is explanatory drawing of the manufacturing method of the structure of this invention. It is a typical explanatory view of a special jig used for reverse electrolysis. It is explanatory drawing of the method of calculating the regularization degree of a pore.

Explanation of symbols

1, 2, 4, 5, 7, 8, 16, 32 Micropore 3, 6, 9 yen 10 Aluminum member 12, 24, 34 Aluminum substrate 14, 30 Anodized film 18 Barrier layer 20, 28 Structure 22, 26 Recess 40 Cathode 42 Packing 44 Electrolyte inlet 46 Electrolyte outlet

Claims (11)

By subjecting an aluminum member having an aluminum substrate and an anodized film present on the surface of the aluminum substrate to electrolysis as a cathode, the anodized film and the aluminum substrate are separated to form a structure comprising the anodized film. A method for producing a structure, comprising a separation step.
In the peeling step, the electrolysis is performed so that a current flows on the surface of the anodized film.   The method for producing a structure according to claim 1, wherein in the peeling step, the electrolysis is performed so that a current flows only on a surface of the anodized film.   3. The structure according to claim 2, wherein in the peeling step, the electrolysis is performed in a state where the electrolytic solution is in contact with the surface of the anodized film and the electrolytic solution is not in contact with a side surface of the anodized film and the aluminum substrate. Manufacturing method. The method for manufacturing a structure according to any one of claims 1 to 3, wherein in the peeling step, the electrolysis is constant voltage electrolysis . In the peeling step, the current value is 0.1 A / dm. ² The method for manufacturing a structure according to claim 4, wherein the electrolysis is terminated after the time point below. From the aluminum substrate having a plurality of depressions by separating the anodized film and the aluminum substrate by electrolysis using an aluminum member having an aluminum substrate and an anodized film present on the surface of the aluminum substrate as a cathode. A peeling step to obtain a structure comprising:
An anodizing treatment step of performing anodizing treatment on the aluminum substrate having the plurality of depressions to obtain an aluminum substrate having an anodized film having micropores on the surface. There,
In the peeling step, the electrolysis is performed so that a current flows on the surface of the anodized film.   The method of manufacturing a structure according to claim 6, wherein in the peeling step, the electrolysis is performed so that a current flows only on a surface of the anodized film.   8. The structure according to claim 7, wherein, in the peeling step, the electrolysis is performed in a state where the electrolytic solution is in contact with the surface of the anodized film and the electrolytic solution is not in contact with a side surface of the anodized film and the aluminum substrate. Manufacturing method. The method for manufacturing a structure according to any one of claims 6 to 8, wherein in the peeling step, the electrolysis is constant voltage electrolysis . In the peeling step, the current value is 0.1 A / dm. ² The method for manufacturing a structure according to claim 9, wherein the electrolysis is terminated after the time point below. Further, after the anodizing treatment step comprises a chemical lysis treatment step of performing chemical dissolution treatment to a structure consisting of an aluminum substrate having an anodized film having the micropores on the surface, any of claims 6-10 A method for producing the structure according to 1.

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