JP2010047454A - Carbon material having regular unevenness pattern on its surface, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbon material having a fine and regular unevenness pattern on its surface, and a manufacturing method thereof. <P>SOLUTION: There is provided a carbon material having a fine and regular unevenness pattern on its surface, manufactured by using an aluminum oxide mold having a regular hole array structure on its surface obtained by anodizing an aluminum material, or a negative mold fabricated using the aluminum oxide mold as a template, transferring the surface structure of the mold to a polymer to become a carbon precursor, and thereafter subjecting the polymer to a carbonization treatment. There is also provided a manufacturing method of the carbon material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a carbon material having a fine and regular concavo-convex pattern on a surface, produced using an imprint technique, and a method for producing the same.

  The nanoimprint method can transfer sub-micron to nanometer-scale fine concavo-convex patterns onto the substrate surface at once, so various functional devices such as water and oil repellent films, antireflection films, and cell culture sheets It is expected as a technique for manufacturing.

  This method is to transfer a pattern by pressing a mold with a fine pattern against a substrate made of polymer or glass, but once the mold with a nano pattern is made, the mold Since it can be used repeatedly, it is characterized in that high throughput processing is possible as compared with other microfabrication methods such as electron beam lithography. Usually, since a mold used for imprinting is manufactured by various lithography techniques, it is difficult to form a pattern with a large area. However, if a regular structure material formed in a self-organized manner is applied as a mold, It can also solve various problems. Anodized porous alumina obtained by anodizing an aluminum material in an acidic bath is a typical self-organized ordered structure material having a hole array structure in which cylindrical pores are regularly arranged. Alternatively, it is possible to form a large-area hole array structure or a pillar array structure by using a negative structure manufactured as a mold as a mold (Non-patent Document 1). Various researches have been conducted on the formation of microstructures by nanoimprinting and its application to various functional devices, but to date materials for structural transfer are thermoplastic resins and photocuring. It was limited to the functional resin, the low melting glass, and the sol-gel material.

  Since carbon materials whose structures are controlled at the nanoscale can be expected to be used in various applications such as catalysts, functional electrodes, and electronic materials, the establishment of their production methods is an important issue. Until now, structural control of carbon materials has been attempted by several methods including a mold process and dry etching. According to the mold process, an organic substance that becomes a carbon precursor is introduced into the voids of the mold, carbonized by heat treatment in an inert gas, and then the mold is dissolved and removed, so that the structure is controlled to an inverse opal structure and the like. It has been reported that a carbon material can be obtained (Patent Document 1). However, these methods have a problem that throughput is low because it is necessary to dissolve and remove the template in order to obtain a carbon material whose structure is controlled.

If the imprint method can be applied to the fabrication of carbon material nanostructures, it can be expected to solve the problems of the conventional method and be effective as a high-throughput method. No example of applying the imprint method to the production of a carbon material with a controlled structure is reported.
JP 2005-262324 A T. Yanagishita, K. Nishio, and H. Masuda, Jpn. J. Appl. Phys., 45, L804 (2006)

  The present invention provides a technique for efficiently producing a carbon material having a fine concavo-convex pattern formed on a surface expected to be applied to a wide range of fields by a nanoimprint method. In particular, a means for easily obtaining a carbon material having a fine concavo-convex pattern on its surface by using an anodized porous alumina obtained by anodizing an aluminum material or a negative mold prepared using the same as a mold. It was completed as a result of intensive studies. An object of the present invention is to provide a carbon material having a fine concavo-convex pattern in which pores or protrusions of uniform size are regularly arranged and formed on the surface, and a method for producing the same.

  In order to solve the above object, the present invention has the following configuration. That is, the carbon material having a regular uneven pattern on the surface according to the present invention is characterized in that an organic material having a regular fine uneven pattern formed on the surface by an imprint process is carbonized by heat treatment. It consists of what to do. In other words, the surface of an organic material that functions as a carbon precursor by the imprint process has a sub-micron to nanometer size composed of convex and concave portions such as line and space patterns, hole array patterns, and pillar array patterns. After forming a fine and regular concavo-convex pattern, a carbon material having a regular concavo-convex pattern on the surface is obtained by carbonization treatment by heating.

  In the carbon material having a regular concavo-convex pattern on the surface according to the present invention, the concavo-convex pattern formed on the surface has a hole array structure or a pillar array structure, and its pore diameter (hole array structure) or protrusion diameter (pillar array). A structure having a structure in the range of 10 nm to 1 μm can be obtained.

  Further, it is possible to obtain a carbon material having a hole array pattern in which the aspect ratio represented by the ratio of the pore depth and the pore diameter of the hole array structure (pore depth / pore diameter) is 0.5 or more, It is also possible to obtain a structure having an aspect ratio of 4 or more. In addition, a carbon material having an aspect ratio (pillar height / pillar diameter) value of 0.5 or more shown as a value obtained by dividing the pillar height of the pillar array structure by the pillar diameter can be obtained. If an aspect ratio mold is used, a structure having an aspect ratio of 10 or more can be obtained.

  Further, the organic material to be carbonized may be configured to be provided on a substrate made of a material different from the organic material. That is, in the present invention, a carbon material having a fine concavo-convex pattern is obtained by carbonizing after forming a fine pattern on the surface of the carbon precursor based on the imprint method. It is possible to form a fine pattern on the precursor thin film and perform carbonization. In the carbonization treatment, since heating is usually performed at a temperature of 800 ° C. or higher, a material having a heat resistance of 800 ° C. or higher, such as quartz, silicon, sapphire, or a carbon material, can be used for the substrate.

  The method for producing a carbon material having a regular concavo-convex pattern on the surface according to the present invention includes forming a regular fine concavo-convex pattern on the surface of an organic material by an imprint process, and subjecting the organic material to a heat treatment. It consists of a method characterized by carbonizing the system material. As described above, the surface of an organic material that functions as a carbon precursor by the imprint process has a sub-micron to nanometer structure composed of convex and concave portions such as line and space patterns, hole array patterns, and pillar array patterns. This is a method of obtaining a carbon material having a regular concavo-convex pattern on the surface by forming a fine concavo-convex pattern with a fine size and then carbonizing by heating.

  Also in the method for producing a carbon material having a regular concavo-convex pattern on the surface according to the present invention, the concavo-convex pattern formed on the surface has a hole array structure or a pillar array structure, and the pore diameter or protrusion diameter is from 10 nm. The structure may be in the range of 1 μm.

  The aspect ratio (pore depth / pore diameter) of the hole array structure may be 0.5 or more, and the aspect ratio (pore depth / pore diameter) of the hole array structure A structure having a value of 4 or more can also be used. The pillar array structure may have a structure with an aspect ratio (pillar height / pillar diameter) of 0.5 or more, and the pillar array structure has an aspect ratio (pillar height / pillar diameter) of 10 or more. It can also be set as the structure which is.

  Further, it is possible to employ a method in which the organic material is provided on a substrate made of a material different from the organic material, and the organic material is carbonized. It is preferable to use a material having the above heat resistance temperature.

  In the method for producing a carbon material having a regular uneven pattern on the surface according to the present invention, a polymer monomer or semipolymer that functions as a carbon precursor as the organic material, and further a crosslinking agent. Using the added polymer, the imprint mold is pressed against the polymer material layer and solidified by applying light irradiation or heating treatment to the polymer material layer, and then from the polymer material layer solidified. By peeling off the imprint mold, a regular fine uneven pattern can be formed on the surface of the polymer material layer, and a carbon material having a regular uneven pattern on the surface can be obtained.

  In addition, a polymer material that functions as a carbon precursor as the organic material, such as a crosslinkable resin having a low degree of polymerization, is softened by heating the polymer material to a temperature equal to or higher than the softening point. After imprinting the imprint mold against the polymer material and transferring the pattern of the mold, heat treatment is applied to the polymer material to carbonize the polymer material, thereby forming a regular uneven pattern on the surface. The carbon material which has can be obtained.

  As the polymer that functions as a carbon precursor, a photocurable crosslinked polymer, a thermosetting resin, or the like can be used.In particular, any of a furan resin, a phenol resin, an epoxy resin, and a crosslinkable acrylic resin, Alternatively, it is desirable to use a mixture thereof.

  As the mold for imprinting, use anodized porous alumina having a regular hole array structure on the surface formed by anodization of an aluminum material, or a mold having a negative type pillar array structure made using it as a mold. Can do.

  In addition, anodized porous alumina prepared using sulfuric acid as an electrolytic solution at a conversion voltage of 10 V to 30 V, or a negative type prepared using it as a mold, or manufactured using an oxalic acid as an electrolytic solution at a conversion voltage of 30 V to 130 V Anodized porous alumina, or a negative type produced using the same as a mold, or anodized porous alumina produced using phosphoric acid as an electrolytic solution at a conversion voltage of 180 to 200 V, or a negative type produced using the same as a mold By using as an imprint mold, it is possible to obtain an imprint mold having a hole array structure or a pillar array structure having higher regularity.

  Furthermore, after anodizing at a constant voltage for a long time, the oxide film was once removed, and anodized porous alumina prepared by anodizing again under the same conditions, or a negative type prepared using it as a mold It can be used as an imprint mold, and by adopting such a method, an imprint mold having high hole arrangement regularity can be obtained.

  Prior to anodic oxidation, a fine depression was formed on the surface of the aluminum, and anodized porous alumina prepared using this as a starting point for pore generation during anodic oxidation, or a negative mold made using it as a mold, was imprinted. By using such a method, it is possible to produce anodized porous alumina with controlled pore arrangement. A controlled carbon material can also be formed.

  Also, anodized porous alumina having pores whose pore diameters are continuously changed by repeatedly performing anodization and pore diameter enlargement processing, or a negative mold made using the same as a mold can be used as an imprint mold. In this way, by using for the imprint, porous alumina having tapered pores produced by a method of repeating the pore diameter enlargement process by anodic oxidation and wet etching, or a negative mold produced using it as a mold, The mold releasability from the carbon precursor material is improved, and as a result, the carbon nanostructure surface can be produced with high accuracy and high throughput.

  Further, a roll-shaped mold in which anodized porous alumina formed on the surface of roll-shaped aluminum or metal pillars prepared using the same is arranged as a mold can also be used as a continuous imprint mold. By using such a roll-shaped imprint mold, the carbon precursor material can be continuously imprinted, thereby further improving the throughput when producing the carbon uneven pattern. Become.

  Thus, according to the carbon material having a regular concavo-convex pattern on the surface and the manufacturing method thereof according to the present invention, a fine concavo-convex pattern in which pores or protrusions of uniform size are regularly arranged is formed on the surface. A carbon material can be obtained efficiently and easily. The carbon material having a regular uneven pattern on its surface can be expected to be applied to a wide range of fields.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an anodized porous alumina 2 having a hole array structure in which pores 3 are regularly arranged by forming a layer of anodized porous alumina 2 functioning as a mold on the surface of an aluminum material 1. The case where it applies to the imprint of the polymer material 4 which functions as a body is shown typically. By transferring the fine and regular uneven structure on the surface of the anodized porous alumina 2 to the surface of the polymer material 4 and then heating the sample in an inert gas atmosphere to perform carbonization treatment, the surface is ordered. The carbon material 5 having an uneven pattern with a fine pillar array structure can be produced.

  FIG. 2 shows an example in which a polymer material 8 is inserted by a negative mold 7 obtained by dissolving and removing the mold 6 after filling the pores 3 with the material 6 using the anodized porous alumina 2 as a mold. The case where the carbon material 9 which has the uneven | corrugated pattern of a fine hole array structure is produced typically by printing and performing the carbonization process by heating after that is shown typically. It was found that by using the mold 7 produced by the mold process, it is possible to produce the carbon material 9 having the hole array pattern formed on the surface.

  In FIG. 3, a polymer material is provided as a carbon material precursor 12 on a substrate 11 having heat resistance, and the anodized porous alumina 2 as shown in FIG. Imprinting is performed using the mold 13 having the above layer, and after forming a fine concavo-convex pattern on the surface of the carbon material precursor 12, the mold 13 is peeled off, and the carbon material precursor 12 is subjected to carbonization treatment, whereby a substrate is obtained. 11 is formed by forming a carbon material 14 having a desired fine surface structure. Carbonization of a polymer material generally requires heat treatment at a high temperature of 800 ° C. or higher, preferably 1000 ° C. or higher. Therefore, it is desirable to use a material having excellent heat resistance such as quartz for the substrate 11.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by this Example.
Example 1 [Formation of carbon pillar array using furan resin]
A SiC mold having a structure in which protrusions were regularly arranged with a period of 500 nm was pressed against the surface of an aluminum plate having a purity of 99.99% to form a fine uneven pattern on the surface. The textured aluminum plate was anodized for 2 minutes in a phosphoric acid aqueous solution adjusted to a concentration of 0.1 M at a bath temperature of 0 ° C. and a direct current of 200 V. Thereafter, the substrate was immersed in a 10% by weight phosphoric acid aqueous solution for 90 minutes, and subjected to pore diameter expansion treatment. The produced anodized porous alumina was immersed in a fluoroalkylsilane solution and subjected to a surface release treatment. The porous alumina mold after the mold release treatment was immersed in a furfuryl alcohol solution added with 2 wt% oxalic acid and kept at 80 ° C. for 24 hours to be polymerized and solidified to form a furan resin. The mold was peeled from the furan resin after polymerization and solidification, and a fine protrusion pattern was obtained on the surface of the furan resin. Then, carbonization was performed by heat-processing at 1000 degreeC for 5 hours using a vacuum heating furnace. FIG. 4 shows an observation result of the carbon material pillar array 21 after carbonization treatment by an electron microscope.

Example 2 [Formation of Hall Array Using Furan Resin]
A SiC mold having a structure in which protrusions were regularly arranged with a period of 500 nm was pressed against the surface of an aluminum plate having a purity of 99.99% to form a fine uneven pattern on the surface. The textured aluminum plate was anodized in a phosphoric acid aqueous solution adjusted to a concentration of 0.1 M for 20 minutes at a bath temperature of 0 ° C. and a direct current of 200 V. Thereafter, it was immersed in a 10% by weight phosphoric acid aqueous solution for 30 minutes, and subjected to a pore size expansion treatment. Thereafter, Pt functioning as an electrode layer during Ni electrodeposition was sputtered to a thickness of 100 nm on the surface of the sample using an ion beam sputtering apparatus. After electrodeposition of Ni in the pores and the surface of the pores of the anodized porous alumina provided with the electrode layer, a negative mold in which Ni pillars were regularly arranged was obtained by dissolving and removing the template. After the surface of the produced mold was treated with a mold release agent, it was immersed in furfuryl alcohol in which 2 wt% oxalic acid was dissolved, and kept at 80 ° C. for 24 hours for polymerization and solidification. The metal mold was peeled from the obtained furan resin, and carbonized by performing a heat treatment at 1000 ° C. for 5 hours in a vacuum heating furnace. FIG. 5 shows an observation result of the carbon material hole array 31 after carbonization treatment by an electron microscope.

Example 3 [Production of carbon nanopattern by thermal imprinting on a semi-polymer of furfuryl alcohol]
A SiC mold having a structure in which protrusions were regularly arranged with a period of 500 nm was pressed against the surface of an aluminum plate having a purity of 99.99% to form a fine uneven pattern on the surface. The textured aluminum plate was anodized for 10 seconds in a phosphoric acid aqueous solution adjusted to a concentration of 0.1 M at a bath temperature of 0 ° C. and a direct current of 200 V. Thereafter, it was immersed in a 10% by weight phosphoric acid aqueous solution for 25 minutes and subjected to a pore size expansion treatment. By repeating this operation five times, porous alumina having tapered pores having a pore period of 500 nm, a pore opening portion of 400 nm, a bottom portion of 1500 nm, and a pore depth of 800 nm was obtained. The sample surface was coated with Pt by 50 nm by an ion beam sputtering apparatus, and then Ni plating was performed using the Pt layer as an electrode. After Ni was electrodeposited in the alumina pores and on the surface thereof, the mold was dissolved and removed to obtain a Ni mold. The surface of the obtained sample was surface-modified with a fluorine-based surface treatment agent. The mold subjected to the mold release treatment was pressed against a furan resin semi-polymer sheet under a heating condition of 150 ° C. under a condition of 2 t / cm ² , and thermal imprinting was performed to form a pattern. A furan resin semi-polymer with a fine pattern formed on the surface is heat treated at 80 ° C. for 10 hours to form a furan resin, followed by heat treatment in a vacuum heating furnace at 1000 ° C. for 5 hours, followed by carbonization treatment. A carbon material in which a hollow pattern was formed was obtained.

Example 4 [Formation of carbon pillar array by carbonization of polymer nanostructure formed by photoimprint]
The surface of the porous alumina mold produced by the same method as in Example 1 was subjected to mold release treatment. Using this as a mold, photoimprinting was performed on a photocurable resin to form a polymer pillar array on the surface of the quartz substrate. The obtained polymer pillar array was subjected to carbonization treatment by heat treatment at 1000 ° C. for 5 hours in a vacuum heating furnace. In FIG. 6, the observation result by the electron microscope of the carbon material nanostructure 41 of the formed high aspect ratio is shown.

  The carbon material according to the present invention can be developed for any application that requires a fine and regular surface unevenness pattern, and is suitable as an electrode material or the like.

It is a schematic block diagram which shows an example of the manufacturing process of the carbon material of this invention. It is a schematic block diagram which shows another example of the manufacturing process of the carbon material of this invention. It is a schematic block diagram which shows another example of the manufacturing process of the carbon material of this invention. It is a figure which shows the observation result by the electron microscope of the carbon material pillar array obtained in Example 1. FIG. It is a figure which shows the observation result by the electron microscope of the carbon material hole array obtained in Example 2. FIG. It is a figure which shows the observation result by the electron microscope of the carbon material nanostructure obtained in Example 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aluminum material 2 Anodized porous alumina 3 Pore 4 Polymer material 5 Carbon material 6 Filling material 7 Mold 8 Polymer material 9 Carbon material 11 Heat resistant substrate 12 Carbon material precursor 13 Mold 14 Carbon material 21 Carbon material pillar array 31 Charcoal Material Hall Array 41 Carbon Nanostructure

Claims (27)

  A carbon material having a regular concavo-convex pattern on a surface, wherein an organic material having a regular fine concavo-convex pattern formed on the surface by an imprint process is carbonized by heat treatment.   2. The surface according to claim 1, wherein the concavo-convex pattern formed on the surface has a hole array structure or a pillar array structure, and the pore diameter or protrusion diameter is in the range of 10 nm to 1 μm. Carbon material.   The carbon material which has a regular uneven | corrugated pattern on the surface of Claim 2 whose value of the aspect ratio (pore depth / pore diameter) of the said hole array structure is 0.5 or more.   The carbon material which has a regular uneven | corrugated pattern on the surface of Claim 3 whose value of the aspect ratio (pore depth / pore diameter) of the said hole array structure is 4 or more.   The carbon material which has a regular uneven | corrugated pattern on the surface of Claim 2 whose value of the aspect ratio (pillar height / pillar diameter) of the said pillar array structure is 0.5 or more.   The carbon material which has a regular uneven | corrugated pattern on the surface of Claim 5 whose value of the aspect ratio (pillar height / pillar diameter) of the said pillar array structure is 10 or more.   The regular uneven pattern on the surface according to claim 1, wherein the organic material to be carbonized is provided on a substrate made of a material different from the organic material. Carbon material having   The carbon material which has a regular uneven | corrugated pattern on the surface of Claim 7 whose material of the said board | substrate has the heat-resistant temperature of 800 degreeC or more.   A regular concavo-convex pattern is formed on the surface of the organic material by forming a regular fine concavo-convex pattern on the surface of the organic material by an imprint process, and applying heat treatment to the organic material to carbonize the organic material. The manufacturing method of the carbon material which has.   The uneven pattern formed on the surface has a regular uneven pattern on the surface according to claim 9, wherein the uneven pattern formed on the surface has a hole array structure or a pillar array structure, and the pore diameter or protrusion diameter is in the range of 10 nm to 1 μm. Carbon material manufacturing method.   The method for producing a carbon material having a regular concavo-convex pattern on the surface according to claim 10, wherein the value of the aspect ratio (pore depth / pore diameter) of the hole array structure is 0.5 or more.   The method for producing a carbon material having a regular concavo-convex pattern on a surface according to claim 11, wherein the value of the aspect ratio (pore depth / pore diameter) of the hole array structure is 4 or more.   The method for producing a carbon material having a regular concavo-convex pattern on a surface according to claim 10, wherein an aspect ratio (pillar height / pillar diameter) of the pillar array structure is 0.5 or more.   The method for producing a carbon material having a regular uneven pattern on a surface according to claim 13, wherein the pillar array structure has an aspect ratio (pillar height / pillar diameter) of 10 or more.   The regular uneven pattern is formed on the surface according to any one of claims 9 to 14, wherein the organic material is provided on a substrate made of a material different from the organic material, and the organic material is carbonized. The manufacturing method of the carbon material which has.   The manufacturing method of the carbon material which has a regular uneven | corrugated pattern on the surface of Claim 15 using the material which has the heat resistant temperature of 800 degreeC or more for the said board | substrate.   A polymer material that functions as a carbon precursor is used as the organic material, and the polymer material layer is solidified by heat or light while pressing an imprint mold against the polymer material layer. The surface according to any one of claims 9 to 16, wherein a regular fine concavo-convex pattern is formed on the surface of the polymer material layer by peeling the imprint mold from the molecular material layer. Carbon material manufacturing method.   A polymer material that functions as a carbon precursor is used as the organic material, the polymer material is heated to a temperature equal to or higher than a softening point, and an imprint mold is pressed against the polymer material. The carbon material having a regular concavo-convex pattern on the surface according to any one of claims 9 to 16, wherein the polymer material is carbonized by performing heat treatment on the polymer material after pattern transfer of the mold. Method.   The method for producing a carbon material having a regular concavo-convex pattern on the surface according to claim 17 or 18, wherein any of a furan resin, a phenol resin, an epoxy resin, an acrylic resin, or a mixture thereof is used as the carbon precursor.   20. An anodized porous alumina having a regular hole array structure on a surface formed by anodization of an aluminum material, or a mold having a pillar array structure produced using the same as a mold, is used as an imprint mold. The manufacturing method of the carbon material which has a regular uneven | corrugated pattern on the surface in any one of.   The regular uneven pattern on the surface according to claim 20, wherein sulfuric acid is used as an electrolytic solution, and anodized porous alumina prepared at a conversion voltage of 10 V to 30 V or a negative mold prepared using it as a mold is used as an imprint mold. The manufacturing method of the carbon material which has this.   21. Regular irregularities on the surface according to claim 20, wherein oxalic acid is used as an electrolyte, and anodized porous alumina produced at a conversion voltage of 30 V to 130 V or a negative mold produced using the same as a mold is used as an imprint mold. A method for producing a carbon material having a pattern.   21. Regular irregularities on the surface according to claim 20, wherein phosphoric acid is used as an electrolytic solution, and anodized porous alumina produced at a conversion voltage of 180 V to 200 V or a negative mold produced using the same as a mold is used as an imprint mold. A method for producing a carbon material having a pattern.   After anodizing at a constant voltage, once the oxide film is dissolved and removed, anodized porous alumina prepared by anodizing again under the same conditions, or a negative mold made using it as a mold, is an imprint mold The manufacturing method of the carbon material which has a regular uneven | corrugated pattern on the surface in any one of Claims 20-23 used as.   Prior to anodization, a fine depression was formed on the surface of aluminum, and anodized porous alumina prepared using this as a starting point for the generation of pores during anodization, or a negative mold prepared using it as a mold, was used as an imprint mold. The manufacturing method of the carbon material which has a regular uneven | corrugated pattern on the surface in any one of Claims 20-24 used as.   The anodized porous alumina having pores whose pore diameter is continuously changed by repeatedly performing anodization and pore diameter enlargement treatment, or a negative mold produced using the same as a mold, is used as an imprint mold. The manufacturing method of the carbon material which has a regular uneven | corrugated pattern on the surface in any one of.   The anodized porous alumina formed on the surface of roll-shaped aluminum, or a roll-shaped mold in which metal pillars manufactured using the same as a mold are used as a mold for continuous imprinting. The manufacturing method of the carbon material which has a regular uneven | corrugated pattern on the surface.

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