JP2006257170A - Method for forming microporous structure and its application - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a microporous structure by which a fractal structure is formed in the inside of a substance, and its application method. <P>SOLUTION: The method for formation of the microporous structure comprises filling the surroundings of a template consisting of a fine particle having a fractal structure and consisting of a first substance or aggregates thereof with a second substance, hardening the second substance in the template and thereby forming the fractal structure inside the body consisting of the second substance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for forming a microporous structure that forms a fine porous structure inside a solid body and the use thereof, and more particularly to a method for forming a microporous structure that forms a fractal structure inside a solid body and the use thereof. It is.

  The porous material is a material widely used in various fields. For example, inorganic materials such as silica and alumina are used as reaction catalysts, and activated carbon and the like are used as adsorbents. In addition, materials such as plastic foam, which is a synthetic polymer material, are used as weight-reducing materials, heat insulating materials, filter materials, etc., and polysulfone, ceramic, etc. are used as separation membranes.

  Properties required for the porous material include a low density and a large surface area. As a method for forming such a porous structure, as represented by a method for producing polyurethane foam, plastic foam, sponge, etc., bubbles are generated during the reaction, a foaming agent is added, nitrogen gas or carbon dioxide gas is used. There is a method of forming a porous structure inside an object by charging or mechanically stirring (see Patent Document 1). When a functional separation membrane or the like is manufactured, a physical method such as perforation by stretching or etching, or a method using a general nonwoven fabric is used (see Patent Documents 2 and 3).

  By the way, as what has the property calculated | required by said porous material, the solid (henceforth a "fractal solid") which has a fractal structure is mentioned. The fractal solid is a solid that can theoretically be reduced in density to the limit and have an infinite surface area.

  Fractal is a general term for figures, structures, phenomena, etc. that do not have a characteristic length, and the greatest feature is a property called “self-similarity”. More simply, no matter how finely an object is divided, the same shape as the original shape appears.

Recently, it has been clarified that a fractal solid can stay inside a fractal solid without reflecting or absorbing electromagnetic waves (see Non-Patent Document 1). According to Non-Patent Document 1, the frequency of the electromagnetic wave confined inside the fractal solid differs depending on the size of the fractal solid. When the fractal solid is small, the electromagnetic wave having a higher frequency can be confined.
JP-T 8-503720 (published on April 23, 1996) JP 2002-179824 (published June 26, 2002) JP 2000-229228 A (released on August 22, 2000) Takeda et al., Physical Review Letters, 92, 093920 (2004) Shibuichi et al., Journal of Physical Chemistry, 100, 19512-19517 (1996) Tsujii et al., Angewandte Chemie International Edition in English, 36, 1011-1012 (1997) Shibuichi et al., Journal of Colloid and Interface Science, 208, 287-294 (1998)

  Thus, the porous material is a very useful substance, and the method for forming the porous structure is an industrially useful tool. However, the method described in Patent Document 1 has a problem that the pores are large and a fine porous structure cannot be formed. In addition, the methods described in Patent Documents 2 and 3 can form a porous structure that is fine to some extent, but have a problem that the uniformity is poor.

  On the other hand, since the fractal solid forms a fractal structure inside the substance, it is expected that a material having a microporous structure with an extremely small density and an infinite surface area can be developed. However, there is no known method for forming a fractal structure as designed inside a substance.

  Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a method for forming a microporous structure in which a fractal structure is formed inside a solid body, and a method for using the method.

  As a result of intensive investigations in view of the above problems, the inventors of the present invention are different from the substance that forms the fine particles around the fine particles having a fractal structure (hereinafter also referred to as “fractal fine particles”) or a template made of an aggregate thereof. It was found that fractal structures can be formed inside an object made of the cured substance by filling and curing with the substance, and the present invention has been completed.

  That is, in the method for forming a microporous structure according to the present invention, the periphery of a template made of a fractal fine particle made of the first substance or an aggregate of the fractal fine particles is filled with a second substance different from the first substance. A step of curing the second substance in the mold, and a step of separating the object made of the cured second substance and the mold, the second fractal structure of the mold being cured It is characterized by being transferred to a solid body made of a substance.

  Moreover, it is preferable that the formation method of the microporous structure concerning this invention includes the process of producing fractal microparticles using said 1st substance.

  Furthermore, it is preferable that the method for forming a microporous structure according to the present invention includes a step of producing the template made of the fractal fine particles or the aggregate of the fractal fine particles.

  The first substance is preferably an alkyl ketene dimer.

  The microporous structure according to the present invention is characterized by having a fractal structure inside a solid body.

  A microporous structure according to the present invention is manufactured by a manufacturing method including the above-described method for forming a microporous structure, and has a fractal structure inside an object.

  In addition, the microporous structure according to the present invention is preferably manufactured by the method for forming a microporous structure including a step of preparing fractal fine particles using the first substance.

  Furthermore, it is preferable that the microporous structure according to the present invention is manufactured by the method for forming a microporous structure including the step of producing the template from the fractal fine particles or the aggregate of the fractal fine particles.

  A device according to the present invention is characterized by including the above-described microporous structure.

  According to the method for forming a microporous structure according to the present invention, a fractal fine particle consisting of a first substance or an aggregate thereof is used as a template, and the second substance is cured in the template, thereby forming the second substance. A microporous structure having a fractal structure inside the object can be produced. Therefore, it is possible to produce a material having a microporous structure having a desired fractal structure.

  In addition, the microporous structure produced by the method for forming a microporous structure according to the present invention has a very small volume and is almost a three-dimensional space, so that the density is very small and the surface area is very large. Therefore, the microporous structure according to the present invention has an effect that it can be widely used industrially as a microporous material.

<1. Method for forming fine porous structure>
[Embodiment 1]
One embodiment of the present invention will be described below with reference to FIG. 1, but the present invention is not limited to this.

  As shown in FIG. 1, the method for forming a microporous structure according to the present invention uses a second material different from the first material around the fractal fine particles made of the first substance or the template made of the aggregate of the fractal fine particles. A step of curing the second substance in the mold (hereinafter also referred to as “molding step”), and a step of separating the object made of the cured second substance from the mold (hereinafter referred to as “molding step”). , Also referred to as “separation step”), and other specific steps, materials, conditions, equipment used, equipment used, etc. are not particularly limited. Hereinafter, each step will be described in detail.

  In this specification, “fractal structure” means a structure of a geometric figure having self-similar properties and non-integer dimensional features in a structure that becomes increasingly fine, and has a specific shape and size. Etc. are not particularly limited. For example, any of a flake shape, a prismatic shape, a columnar shape, a pyramid shape, a conical shape, a needle shape, and the like, and a fractal structure formed by combining these shapes in a complicated manner can be given.

  Further, in this specification, “transferring the fractal structure of substance A to substance B” means that the fractal structure of substance B is formed using the fractal structure of substance A as a template. This means that the nature and / or shape of the fractal structure with B is the same or substantially the same. Here, “substantially the same” means that they may be slightly different within a reasonable range in which the gist of the present invention can be achieved. In the present invention, it is particularly preferable that the fractal structure of the substance A is the same as the fractal structure of the substance B.

  In the present specification, “fine particles” refers to particles having a particle size of 1 nm or more and 1 mm or less. In the present invention, it is particularly preferable that the fine particles have a size of 10 nm to 100 μm.

  Furthermore, in the present specification, the “microporous structure” is a structure formed inside a solid body and means a number of fine pore structures. Further, the “microporous structure” refers to a structure having the above “microporous structure” inside a solid body, and is particularly preferably a fractal microporous structure having a fractal structure inside the solid body. The pore size of the fine porous structure in the present invention is determined depending on the particle size of the fractal fine particles, but is preferably 1 nm or more and 1 mm or less, and more preferably 10 nm or more and 100 μm or less.

  In the present specification, “around the mold” refers to the periphery of the fractal fine particles or aggregates thereof.

  In the “molding step”, the periphery of the mold is filled with a “second substance” different from the “first substance”, and the “second substance” is cured in the mold (see FIG. 1). ).

  In the fractal fine particles constituting the template, the “first substance” is not particularly limited as long as it is capable of forming a fractal structure. For example, a substance that forms a fractal structure in a self-organized manner such as an alkyl ketene dimer (hereinafter also referred to as “AKD”), a dialkyl ketone, an anodized aluminum surface, and the like (see Non-Patent Documents 2 to 4 above), And a mixture of these with other substances.

  The “second substance” may be any substance other than the “first substance”, and the specific configuration thereof is not particularly limited. For example, a metal alkoxide, an isocyanate resin, a phenol resin, and a urethane resin can be selected and used. Furthermore, a polymer composed of a fluorine-based monomer, polyethylene, polypropylene, polystyrene, polyacrylic acid ester, polymethyl methacrylate, and the like can also be used. As the “second substance”, these compounds may be used alone or in combination. In addition, when mixing and using, the mixing ratio is not specifically limited.

  In the “molding step”, the method of curing the “second substance” is not particularly limited, and a conventionally known method can be used. For example, in the case where the above-exemplified substance is used as the “second substance”, a method of curing with heat, light, or ultraviolet light can be used.

  Further, a method of filling the periphery of the mold with the “second substance” is not particularly limited, and examples thereof include a method of pouring the “second substance” into the mold.

  As the “second substance” according to the present invention, alkoxysilane is preferably used. Specifically, γ- (meth) acryloxypropyltrialkoxysilane, γ-glycidoxypropyltrialkoxysilane, vinyltrialkoxysilane, tetraalkoxysilane, γ-mercaptopropyltrialkoxysilane, γ-chloropropyltrialkoxy Silane or the like can be used, and is not particularly limited. From the viewpoint of the storage stability of the resin composition, in particular, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycine Sidoxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, tetramethoxysilane, and tetraethoxysilane are preferred.

  Also, tetramethoxy orthotitanate, tetraethoxy orthotitanate, tetrapropyl orthotitanate, tetraisopropyl orthotitanate, n-tetrabutyl orthotitanate, sec-tetrabutyl orthotitanate, tert-tetrabutyl orthotitanate, tetraethyl Metal alkoxides such as zirconate, tetrabutyl zirconate, tetrapropyl zirconate, aluminum triethoxide, n-aluminum tributoxide, sec-aluminum tributoxide, and tert-aluminum tributoxide can be used.

  Furthermore, tetraalkyl orthosilicate can be used as the “second substance”. Examples thereof include tetramethyl orthosilicate (hereinafter also referred to as “TMOS”), tetraethyl orthosilicate, tetrapropyl orthosilicate, tetraisopropyl orthosilicate, tetrabutyl orthosilicate, and the like.

  Further, a metal may be used as the “second substance”. For example, a conventionally known metal material capable of forming a porous metal such as a single metal such as zinc, nickel, iron, aluminum, platinum, lead, gold, or silver, an alloy thereof, or stainless steel can be used.

  In addition to the above "second substance", various additives such as antioxidants, colorants, ultraviolet absorbers, light stabilizers, thermal polymerization inhibitors, leveling agents, surfactants, storage stabilizers, plasticizers A lubricant, a solvent, a filler, an anti-aging agent, a wettability improving agent and the like may be blended as necessary.

  In the “separation step”, the cured “second substance” is separated from the mold (see FIG. 1). In this step, a method for separating the cured object made of the “second substance” from the mold can be a conventionally known method, and is not particularly limited. For example, by heating, only the fractal fine particles are completely burned, and the mold and the hardened “second substance” can be separated.

  As described above, a microporous structure having a desired fractal structure can be formed inside an object by using the method for forming a microporous structure according to the present invention. As described above, a microporous structure having a fractal structure inside an object can be used for technological development of various products that require properties of low density and large surface area.

  Therefore, the method for forming a microporous structure according to the present invention can be used for, for example, development and production of materials having a microporous structure inside various objects. In particular, it can be used as a method for imparting a microporous structure having the properties of low density and large surface area.

  Specifically, heat insulating materials, sound absorbing materials, adsorbing materials, weight reducing materials, building materials such as filter materials, electrical equipment such as computers and mobile phones, functional separation membranes, cosmetic powders, water / oil absorbing materials, catalysts and It can be used for a catalyst carrier, a material for preventing magnetic wave interference, a heating furnace, an electromagnetic wave absorbing material, a method for producing a material such as an electromagnetic wave shielding filter, and the like.

[Embodiment 2]
Another embodiment of the present invention will be described as follows. For convenience of explanation, the same member name is used for a member having the same function as the member used in “Embodiment 1”, and the description thereof is omitted.

  In addition to the configuration of “Embodiment 1”, the method for forming a microporous structure according to the present invention includes a step of producing fractal fine particles using a first substance (hereinafter also referred to as “fine particle production step”) and / or Alternatively, it may include a step of producing a template made of the fractal fine particles or the aggregate of the fractal fine particles (hereinafter also referred to as “template producing step”).

  In the “fine particle production step”, fractal fine particles are produced using the first substance. As the “first substance” used in this step, the same kind of substance as the “first substance” in Embodiment 1 can be used.

  The method for producing fractal fine particles using the “first substance” may be a conventionally known method, and is not particularly limited. For example, a method of dissolving or corroding a solid surface by electrolysis, chemical reaction, microbial reaction, etc., a method of depositing a substance on the solid surface by electrolysis or diffusion-controlled aggregation, a method of attaching fine particle aggregates to a solid surface, When two phases that are incompatible are mixed and phase separation proceeds to create a phase separation pattern in which the two phases are intricate with each other, either one of the materials can be eluted, or AKD, dialkyl ketone, etc. Thus, it is possible to use a method using a material that naturally forms a fractal structure at the time of curing from a melt or a solution.

  Specifically, when a substance that forms a fractal structure such as AKD or dialkyl ketone is used as the “first substance”, the “first substance” dissolved in an organic solvent is sprayed. By leaving the fine particles formed in this manner, fractal fine particles can be formed. At this time, the temperature at which the fine particles are allowed to stand is not particularly limited as long as fractal fine particles are formed, but room temperature is preferable. Further, the standing time may be a time necessary for forming the fractal fine particles, and is not particularly limited, but is preferably 24 hours or more, and more preferably 4 weeks or more.

  Further, when the substance that forms a fractal structure such as AKD or dialkyl ketone as described above is used as the “first substance”, the “first substance” dissolved in an organic solvent is used. It can also be formed by cooling, freeze-drying, and annealing. The annealing temperature is not particularly limited.

  As described above, when the “first substance” is dissolved in an organic solvent, the organic solvent to be used is not particularly limited, but a volatile one is desirable. For example, alkanes such as n-hexane and heptane, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, acetates such as butyl acetate, alcohols such as methanol, ethanol and butanol, and aromatic compounds such as toluene and xylene Amides such as dimethylsulfoxide, dimethylformamide and dimethylacetamide, and compounds such as carbon tetrachloride, chloroform and tetrahydrofuran can be used.

  In the “template production step”, a template is produced using the fractal fine particles or aggregates thereof. The method for producing the template used in this step is not particularly limited as long as the fractal fine particles or the aggregate thereof can be fixed in a stationary state. For example, it can be produced by arranging the fractal fine particles or an aggregate thereof in a container made of glass, metal or the like.

  Further, the “template preparation step” and the “fine particle preparation step” may be combined into one step. That is, the preparation of the fractal fine particles and the preparation of the template may be performed simultaneously. For example, the fractal fine particles may be produced in the container used in the “template production step”, and the container containing the fractal fine particles may be used as a mold as it is.

<2. Microporous structure>
The present invention also includes a microporous structure produced using the above-described method for forming a microporous structure. Details of the microporous structure according to the present invention will be described below. For convenience of explanation, the same member name is used for a member having the same function as the member used in the above-mentioned “1. Method for forming a microporous structure”, and the description thereof is omitted.

  That is, the microporous structure according to the present invention is only required to be manufactured by a manufacturing method including the above-described microporous structure forming method, and other specific structures such as material, size, and shape are particularly limited. Is not to be done.

  The fractal structure of the “first substance” is transferred to the microporous structure according to the present invention, and the microporous structure is the same as or substantially the same as the fractal structure of the “first substance”. It is preferable that it is and it is especially preferable that it is the same.

  Since the microporous structure according to the present invention has a fractal structure inside the object, the density is small and the surface area is large. Therefore, it can be used as a porous material, particularly a fine porous material.

Furthermore, since the microporous structure according to the present invention is a fractal solid, electromagnetic waves can be confined therein (see Non-Patent Document 1). The frequency of the electromagnetic wave that can be confined inside the fractal solid differs depending on the size of the fractal solid. When the fractal solid is small, the electromagnetic wave having a higher frequency can be confined. That is, by reducing the size of the microporous structure according to the present invention, light that is one type of high-frequency electromagnetic waves can be confined within the pores of the microporous structure. Therefore, the microporous structure according to the present invention can be used as a material for confining electromagnetic waves including light.
As described above, the microporous structure according to the present invention specifically includes a heat insulating material, a sound absorbing material, an adsorbing material, a weight reducing material, a building material such as a filtering material, an electric device such as a computer and a mobile phone, and functionality It can be suitably used as a material such as a separation membrane, a catalyst and a catalyst carrier, a material for preventing magnetic wave interference, a heating furnace, an electromagnetic wave absorbing material, an electromagnetic wave blocking filter, a cosmetic powder, and a water / oil absorbing material.

<3. Device with microporous structure>
Various devices provided with the microporous structure are also included in the present invention. Details of the device including the microporous structure according to the present invention will be described below.

  In this specification, “device” means a wide range of items including comprehensive equipment, products, and functional materials, and various conditions such as specific configuration, application, shape, size, etc. Is not particularly limited.

  Examples of the microporous structure according to the present invention include various devices and products such as the above-described computer, mobile phone, and heating furnace. More specifically, it will be described as follows.

  According to Non-Patent Document 1, even if the irradiation of electromagnetic waves is stopped, the electromagnetic waves can be confined inside the fractal solid for 1 / 10,000,000 seconds. One tenth of a millionth of a second corresponds to a time that can be calculated tens of thousands of times by a conventional supercomputer. Therefore, the microporous structure according to the present invention can be sufficiently used as a component constituting a computer.

  Moreover, the microporous structure according to the present invention can be confined in light by downsizing. Therefore, it can be used as a “light pond” for storing photons like a battery. By combining with the method of extracting the captured photons, it is possible to capture the electromagnetic waves (light) that exist in the air in a large amount and to permanently extract energy. That is, by using the microporous structure according to the present invention, a mobile phone or an electric device that does not use a battery can be realized. Thereby, a mobile phone or an electric device can be further downsized.

  Moreover, an energy efficient heating furnace can be realized by converting the energy of the electromagnetic wave captured by the fine porous structure according to the present invention into heat.

  The present invention is not limited to the configurations described above, and various modifications can be made within the scope of the claims, and the technical means disclosed in different embodiments are appropriately combined. The obtained embodiment is also included in the technical scope of the present invention.

  The present invention will be specifically described with reference to Examples and Comparative Examples and FIGS. 2 to 13, but the present invention is not limited thereto. Those skilled in the art can make various changes, modifications, and alterations without departing from the scope of the present invention.

[Example 1]
First, AKD fine particles having a fractal surface structure (hereinafter also referred to as “fractal AKD fine particles”) are prepared by dissolving AKD, which is a wax that spontaneously forms a fractal structure surface, in n-hexane and spraying the solution. Produced. Thereafter, the prepared fine particles were stored at room temperature under a vacuum of about 1 Pa. FIG. 2 shows the results of preparing a large number of fine particles in accordance with the above method, cutting out a part of them appropriately, and observing them for each elapsed time. As a result, it was found that a fractal structure was spontaneously formed with the passage of time of 24 hours and 4 weeks.

  Next, the fractal AKD fine particles (see FIG. 3 (a)) prepared according to the above method and stored for 4 weeks were added to the TMOS solution prepared as follows and allowed to undergo a sol-gel reaction. The TMOS solution was prepared by mixing TMOS, water, and methanol at a molar ratio of 1: 4: 5. At this time, a neutral phosphate pH standard solution (pH 6.86 at 25 ° C.) was added as a part of water.

  The surface of the gel after the sol-gel reaction was observed with a scanning electron microscope (hereinafter also referred to as “SEM”). As shown in FIGS. 3C and 4, the fractal AKD fine particles were buried in the gel. From this, it was found that when the gap between the fractal AKD fine particles was filled with the TMOS solution, the fractal AKD fine particles were polymerized in accordance with the TMOS solution.

  Furthermore, the gel was washed by immersing acetone in the gel to remove the fractal AKD fine particles. Thereafter, the gel surface was observed by SEM. As a result, as shown in FIG. 5, depressions of almost the same size as the fractal AKD fine particles were observed. No depression of this size was observed when a sol-gel reaction was performed under the above conditions without adding fractal AKD fine particles. From this, it was confirmed that when the fractal AKD fine particles were removed from the gel, a trace due to the fractal AKD fine particles remained inside the gel.

  Further, the gel gelled by the above method was allowed to stand at room temperature for 3 days in the air, and then heated in air at 250 ° C. for 2 hours to burn the fractal AKD fine particles. As a result, a pore shape reflecting the fractal structure of the fractal AKD fine particles as shown in FIG. 6 was formed inside the gel. 6A to 6D show SEM observation images obtained by observing different portions at different magnifications. Moreover, the magnifications of FIGS. 6A to 6D are 2000 times, 2500 times, 1000 times, and 400 times, respectively.

  From the above, it became clear that by using the method according to this example, a fractal solid having a three-dimensional structure depending on the fractal AKD fine particles, not bubbles or the like, can be produced in the gel.

[Example 2]
Fractal AKD microparticles (see FIG. 7) that were prepared in the same manner as in Example 1 and stored for about 4 weeks at room temperature in a vacuum immediately after spraying were collected in a container to prepare a template. 7A to 7D show SEM observation images when the fractal AKD fine particles are observed at magnifications of 5000 times, 2000 times, 2000 times, and 700 times, respectively.

  Next, a tetramethoxysilane solution was poured into the gaps between the prepared molds and polymerized by a gel-sol reaction that occurred spontaneously, and allowed to stand at room temperature for 3 days.

  Finally, by heating in an electric furnace at 500 ° C. for 2 hours to completely burn the fractal AKD fine particles, a sponge-like microporous structure having pores of various sizes of 100 nm to 100 μm is obtained. (See FIG. 8). The obtained microporous structure was subjected to cross-section processing with a focused ion microfabrication apparatus (Focused Ion Beam, hereinafter also referred to as “FIB”), and the microporous structure was observed from above with an SEM. The SEM observation image is shown in FIG. Moreover, the SEM observation image obtained by observing the cross section of the said microporous structure after the cross-section process by FIB by SEM is shown in FIG.8 (b). The enlargement magnification is 700 times.

  When the cross section of the microporous structure was observed using an SEM, it was found that the microporous structure was a three-dimensional structure with a lot of gaps as shown in FIG. 9A to 9D show SEM observation images observed at magnifications of 2000 times, 5000 times, 100,000 times, and 70,000 times, respectively. The left side of each panel shows a cross-sectional observation image by SEM, and the right side shows a cross-sectional pattern.

  Furthermore, the fractal dimension of the fine porous structure was evaluated by the box count method. As a result, as shown in FIG. 10, the fractal dimension D of the three-dimensional cross section was 1.87.

[Comparative Example 1]
A porous glass was produced in the same manner as in Example 1 except that AKD fine particles having no fractal structure were used.

  The cross section of the produced porous glass was observed by SEM as in Example 1 (see FIG. 11), and the obtained SEM observation image is shown in FIG. The left panel in FIG. 11 shows a cross-sectional observation image by SEM, and the right panel in FIG. 11 shows a cross-sectional pattern. Moreover, the magnifications of FIGS. 11A to 11D are 2000 times, 2000 times, 4000 times, and 20000 times, respectively.

  Next, the fractal dimension of the cross section of the porous glass was evaluated by a box count method. As a result, the fractal dimension of the cross section of the porous glass was 1.92. That is, it was found that the porous glass was closer to a plane than the fine porous structure in Example 2.

[Comparative Example 2]
Small glass pieces were produced in the same manner as in Example 1 except that AKD was not used.

  The cross section of the produced glass piece was observed by SEM as in Example 1 (see FIG. 12). As a result, compared with the microporous structure in Example 1 (see FIGS. 8 and 9), the glass piece had a dense cross section and no pores. Moreover, it was 2.0 when the fractal dimension of the cross section of the said glass piece was evaluated by the box count method.

[Comparative Example 3]
First, a TMOS solution was prepared by the following method. 1 ml of H ₂ O in 3 ml of methanol (CH ₃ OH), 0.6 ml of neutral phosphate pH standard solution (pH 6.86 at 25 ° C.), 0.135 ml of formamide, TMOS (Si (OCH ₃ ) ₄ ) 2 ml in order and stirred well.

  Next, the TMOS solution was allowed to stand at room temperature to gel. At this time, gelation occurred in about 12 minutes. The gelation was judged by tilting the reaction vessel and not changing the shape. After gelation, the gelled TMOS solution was allowed to stand for 2 days. Thereafter, the gel was taken out from the container, cut with a knife, and its cross section was observed by SEM. As a result, as shown in FIG. 13, the gel was a dense and bulky gel, and irregularities having a size smaller than 100 nm were observed, but no pores were observed. FIGS. 13A and 13B show SEM observation images of portions having different gel cross sections.

  The present invention is not limited to the configurations described above, and various modifications can be made within the scope of the claims, and technical means disclosed in different embodiments and examples are appropriately used. Embodiments and examples obtained in combination are also included in the technical scope of the present invention.

  INDUSTRIAL APPLICABILITY The present invention can be used in a wide variety of industries in which a porous material can be used. For example, the present invention can be used in equipment, instruments, and industrial products that require properties such as a low density and a large surface area. .

It is a flowchart which shows the outline of the formation method of the microporous structure concerning this invention. In the present Example, it is a figure which shows the result of having observed the mode that the fine particle of AKD forms a fractal structure with time. It is a figure which shows the SEM observation image of the surface after cracking the external appearance of the gel produced by filling the clearance gap between the fractal AKD microparticles | fine-particles in a present Example with the reaction material of a TMOS solution. FIG. 3A is a view showing an SEM observation image of the fractal AKD fine particles used in this example. FIG. 3B is a diagram showing the appearance of the gel after the sol-gel reaction. FIG.3 (c) is a figure which shows the SEM observation image of the cross section after breaking the said gel. It is a figure which shows the SEM observation image of the surface of the gel different from FIG.3 (c) in a present Example. In a present Example, it is a figure which shows the SEM observation image of the cross section of the porous gel obtained by melt | dissolving and removing fractal AKD microparticles | fine-particles with acetone from the gel produced by the method similar to FIG. 6 (a) to 6 (d), in this example, the pores of the fine porous gel obtained by removing the fractal AKD fine particles by heating them in air at 250 ° C. for 2 hours were observed with an SEM. It is a figure which shows an image. FIGS. 7A to 7D are views showing SEM observation images of fractal AKD fine particles in this example. It is a figure which shows the SEM observation image of the external appearance (a) and the cross section (b) of the microporous structure produced by pouring the tetramethoxysilane solution in the casting_mold | template which accumulated the fractal AKD microparticles | fine-particles in a present Example. FIGS. 9A to 9D are diagrams showing cross-sectional observation images of the microporous glass in this example by SEM. It is a figure which shows the result of having evaluated the fractal dimension of the cross section of the microporous structure in a present Example by the box count method. FIGS. 11A to 11D are views showing cross-sectional observation images of the porous glass in this comparative example by SEM. It is a figure which shows the SEM observation image of the normal glass piece in this comparative example. FIG. 12B is an enlarged view of a portion surrounded by a circle in FIG. It is a figure which shows the SEM observation image of the gel which does not have a fractal structure in this comparative example.

Claims (7)

  The periphery of a template made of fine particles having a fractal structure made of a first substance or an aggregate of the fine particles is filled with a second substance different from the first substance, and the second substance is cured in the mold. And a step of separating the cured object from the second substance and the mold, and transferring the fractal structure of the mold to a solid interior of the cured second substance. A method for forming a fine porous structure.   2. The method for forming a microporous structure according to claim 1, further comprising a step of producing fine particles having a fractal structure using the first substance.   The method for forming a microporous structure according to claim 1 or 2, further comprising the step of producing the template comprising the fine particles or the aggregate of the fine particles.   The method for forming a microporous structure according to any one of claims 1 to 3, wherein the first substance is an alkyl ketene dimer.   A microporous structure characterized by having a fractal structure inside a solid body.   6. The microporous structure according to claim 5, wherein the microporous structure is manufactured by a manufacturing method including the method of forming a microporous structure according to any one of claims 1 to 4.   A device comprising the microporous structure according to claim 5.