Method for producing a molded body having a metal-organic framework

Abstract

To provide a molded article on which a metal-organic framework is firmly supported. [Solution] The manufacturing method disclosed herein includes a first preparation step (S10) of mixing a metal ion source and a fibrous material containing a site crosslinkable with the metal ions contained in the metal ion source in a solvent to obtain a first slurry, a second preparation step (S20) of mixing the first slurry with an organic ligand source to obtain a second slurry in which a metal organic framework containing the metal ions and the organic ligands contained in the organic ligand source is arranged around the fibrous material, and a molding step (S30) of molding the second slurry to obtain a molded body in which the metal organic framework is supported on a substrate made of the fibrous material.

Description

[Technical field]

[0001] The present invention relates to a method for producing a molded body having a metal-organic framework. [Background technology]

[0002] In recent years, active research has been conducted on metal organic frameworks (MOFs) as materials used for gas storage and separation, deodorization, and air and water purification. Metal organic frameworks have a lattice structure consisting of metal ions and organic ligands, and have extremely large specific surface areas and pore volumes. In addition, metal organic frameworks can be designed in a variety of structures by changing the types of metal ions and organic ligands, as well as the synthesis conditions. For this reason, they are expected to be used in a wide range of fields.

[0003] For example, Patent Document 1 discloses a sheet-like molded body including a substrate containing a fiber material and a metal-organic framework (porous metal complex) supported on the substrate. Patent Document 1 describes the production of a sheet-like molded body by a wet papermaking method including the following steps: mixing the metal-organic framework, the fiber material, and an organic binder in a solvent to prepare a slurry; making the slurry with a papermaking machine to mold a wet paper; and dehydrating and drying the wet paper. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-154302 A Summary of the Invention [Problem to be solved by the invention]

[0005] According to the investigations of the present inventors, a metal-organic framework has a problem in that it is likely to fall off from the substrate unless it is firmly supported (fixed) on the substrate.

[0006] The present invention has been made in view of the above points, and a main object of the present invention is to provide a molded body in which a metal organic framework is firmly supported on a substrate containing a fibrous material. [Means for solving the problem]

[0007] The present invention provides a method for producing a molded body including a substrate containing a fiber material and a metal organic framework containing metal ions and an organic ligand and supported on the substrate. The method includes a first preparation step of mixing a metal ion source and a fiber material containing a site capable of crosslinking with the metal ions contained in the metal ion source in a solvent to obtain a first slurry, a second preparation step of mixing the first slurry with an organic ligand source to obtain a second slurry in which a metal organic framework containing the metal ions and the organic ligand contained in the organic ligand source is disposed around the fiber material, and a molding step of molding the second slurry to obtain a molded body in which the metal organic framework is supported on a substrate made of the fiber material.

[0008] According to the present invention, the metal organic framework can be supported relatively more firmly on the fiber material, compared with the method of producing a molded body by separately preparing the metal organic framework and the fiber material as in, for example, Patent Document 1. Therefore, the integrity of the substrate (fiber material) and the metal organic framework can be enhanced, and the metal organic framework can be prevented from falling off from the substrate. Effect of the Invention

[0009] According to the present invention, it is possible to provide a molded article in which the metal-organic framework is firmly supported on the substrate and is unlikely to fall off from the substrate. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a flow chart showing a method for producing a molded article according to one embodiment. [Diagram 2] FIG. 2(A) is a schematic diagram of the first slurry after the first preparation step, and FIG. 2(B) is a schematic diagram of the second slurry after the second preparation step. [Diagram 3]FIG. 3(A) is a perspective view of an adsorption filter according to one embodiment, and FIG. 3(B) is a front view of the adsorption filter according to one embodiment. [Figure 4] FIG. 4 shows photographs of the evaluation results according to the comparative example and the embodiment. [Diagram 5] FIG. 5 is a graph showing the evaluation results for the comparative example and the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a molded body according to one embodiment of the present invention will be described with reference to the drawings. It should be noted that the embodiment described here is not intended to limit the present invention. In addition, the same reference numerals are used for members and parts that have the same function, and duplicated descriptions are omitted or simplified as appropriate. In addition, the expression "X to Y" (X and Y are arbitrary numerical values) indicating a range in this specification includes the meaning of "greater than X" and "smaller than Y" as well as the meaning of "X or more and Y or less."

[0012] <Method of manufacturing molded body> The manufacturing method disclosed herein is a manufacturing method of a molded body including a substrate (hereinafter, sometimes simply referred to as "substrate") containing a fiber material and a metal organic framework supported on the substrate. The metal organic framework essentially includes metal ions and organic ligands. The metal organic framework is typically a porous metal complex having a highly regular lattice structure (porous three-dimensional structure) composed of metal ions and organic ligands and including a plurality of pores capable of accommodating specific molecules. The metal organic framework may be composed of metal ions and organic ligands, and may further include other structural parts, for example, inorganic structural parts (inorganic chains). The metal organic framework is preferably a fluorinated metal organic framework containing a fluorine element. In this specification, the term "metal organic framework" is synonymous with a porous coordination polymer (PCP) and a porous metal complex.

[0013] FIG. 1 is a flow chart showing a manufacturing method according to this embodiment. As shown in FIG. 1, the manufacturing method according to this embodiment includes a first preparation step (step S10), a second preparation step (step S20), and a molding step (step S30) in this order. The manufacturing method disclosed herein may further include other steps at any stage. As shown in FIG. 1, it is preferable to perform the first preparation step (step S10) to the molding step (step S30) continuously in-line (in-situ). This can improve productivity and work efficiency.

[0014] The first preparation step (S10) is a step of mixing a metal ion source and a fiber material in a solvent to obtain a first slurry. When the metal ion source is in a powder, sol, gel, or other form, it is preferable to dissolve it in a solvent in advance. It is preferable to disperse the fiber material in a solvent in advance. Therefore, in this embodiment, this step includes an initial solution preparation step (step S11) of mixing the metal ion source and a solvent to prepare an initial solution, a first raw solution preparation step (step S12) of mixing the fiber material and a solvent to prepare a first raw solution, and a first slurry preparation step (step S13) of mixing the initial solution containing the metal ion source and the first raw solution containing the fiber material to obtain a first slurry. The order of the initial solution preparation step (step S11) and the first raw solution preparation step (step S12) is not particularly limited. In addition, this step may further include other steps at any stage.

[0015] In the initial liquid preparation step (step S11), the metal ion source and the solvent are mixed to prepare the initial liquid. Although the order of addition is not particularly limited, in this embodiment, as shown in FIG. 1, the metal ion source is first added to the reaction tank, and then the solvent is added to the reaction tank and mixed. For mixing, a conventionally known stirring and mixing device such as a magnetic stirrer, a planetary mixer, or a disperser can be appropriately used. Mixing is preferably performed until the initial liquid becomes homogeneous. The temperature environment of this step is preferably 10° C. or higher, more preferably 20° C. or higher, from the viewpoint of increasing the solubility of the metal ion source. On the other hand, from the viewpoint of suppressing the volatilization of the solvent, it is preferably 40° C. or lower, more preferably 30° C. or lower.

[0016] The metal ion source is a compound containing at least a metal ion constituting the metal organic framework. As the metal ion source, one or more of those known to be usable for this type of application can be appropriately used. The metal ion source is typically a metal salt. The metal ion source may contain a metal ion and an anion (preferably an anion containing fluorine) constituting the inorganic structural portion of the molded body.

[0017] The metal ions form the lattice structure of the metal-organic framework by bonding with the organic ligand in the second preparation step (step S20) described later. There is no particular limitation on the metal ions, and depending on, for example, the type of organic ligand used and the molecules to be captured by the molded body, one or more types of ions that have been known to be usable for this type of application can be appropriately used. Although not particularly limited, the metal ions are preferably ions of metals belonging to groups 1 to 14 of the periodic table, such as alkali metals, alkaline earth metals, transition metals, noble metals, and rare earth metals. The metal ions are preferably ions of metals belonging to the fourth or fifth period of the periodic table.

[0018] Suitable examples of metals (and typical ionic forms) that make up the metal ions include potassium (K + ), Magnesium (Mg 2+ ), Calcium (Ca 2+ ), Strontium (Sr 2+ ), Scandium (Sc 3+ ), yttrium (Y 3+ ), Titanium (Ti 4+ ), Zirconium (Zr 4+ ), Vanadium (V 2+ , V 3+ , V 4+ , V 5+ ), Chromium (Cr 3+ ,Cr 6+ ), Tungsten (W 6+ ), Molybdenum (Mo 3+ , Mo 6+ ), Manganese (Mn 2+ ), iron (Fe 2+, Fe 3+ ), Cobalt (Co 2+ , Co 3+ ), Nickel (Ni 2+ , Ni 3+ ), Copper (Cu 2+ ), silver (Ag + ), Zinc (Zn 2+ ), Cadmium (Cd 2+ ), Aluminum (Al 3+ ), Gallium (Ga 3+ ), Indium (In 3+ ), Tin (Sn 2+ Sn 4+ ) and the like. Among them, the metal ion preferably contains an ion of a transition metal having a valence of 2 to 4, and more preferably contains Cu ions. These metals tend to bond strongly to the fibrous material in the first slurry. In addition, since the complex formation rate is high, the lattice structure of the metal-organic framework can be favorably grown around the fibrous material in the second preparation step (step S20) described later.

[0019] The solvent is typically water, but may be a mixed solvent mainly composed of water. As the solvent other than water constituting the mixed solvent, an organic solvent that can be mixed uniformly with water, for example, a lower alcohol such as methanol, ethanol, or propanol, or a lower ketone, etc. can be used. As the water, from the viewpoint of preventing the inclusion of impurities, purified water such as ion-exchanged water, distilled water, ultrafiltered water, and reverse osmosis water can be suitably used.

[0020] The initial solution is a solution in which at least the metal ions of the metal ion source are dissolved in a solvent. For example, the metal ion source is Cu(BF 4 ) 2 When the solvent is water, the initial solution contains Cu as the metal ion. 2+ and tetrafluoroborate ([BF 4 ] - ) is dissolved in water as a solvent. Although not particularly limited, the concentration of metal ions in the initial solution is preferably 0.1 to 1 mol / L, more preferably 0.1 to 0.5 mol / L, and even more preferably 0.1 to 0.12 mol / L.

[0021] In the first raw solution preparation step (step S12), the fiber material is mixed with a solvent to prepare the first raw solution. The first raw solution is typically a dispersion liquid in which the fiber material is dispersed in the solvent. For mixing, a conventionally known stirring and mixing device as described above can be appropriately used. Mixing is preferably performed until the first raw solution becomes homogeneous. The temperature environment of this step is preferably 10°C or higher, more preferably 20°C or higher. On the other hand, from the viewpoint of suppressing the evaporation of the solvent, it is preferably 40°C or lower, more preferably 30°C or lower. As the solvent, one or more of the media exemplified as those usable for the initial liquid can be appropriately used. The solvent may be the same as or different from the initial liquid. The solvent is typically water.

[0022] The fiber material constitutes the substrate portion of the molded article. In the technology disclosed herein, at least a part of the fiber material has a site capable of crosslinking (bonding) with a metal ion. This allows the metal organic framework to be firmly supported on the fiber material (substrate). The site capable of crosslinking with a metal ion (hereinafter sometimes simply referred to as a "crosslinkable site") is typically a functional group. Suitable examples of the crosslinkable site include functional groups containing at least one of a hydroxyl group and a nitrogen atom, preferably functional groups having nucleophilicity, such as a hydroxyl group (-OH), a carboxyl group (-C(=O)OH), an amide group (-C(=O)NH), an amino group (-NH-, -NH 2 ), amide bond (for example, -C(=O)-NH-), etc. Among them, an amino group, which is a functional group containing a nitrogen atom, and an amide bond are preferable. This makes it easier to strongly bind to the metal ions in the first slurry.

[0023] The fiber material may be composed of only a fiber material having a crosslinkable site (first fiber material), or may further include a fiber material not having a crosslinkable site (second fiber material) in addition to the first fiber material. From the viewpoint of exerting the effects of the technology disclosed herein at a high level, it is preferable that the fiber material is composed mainly of the first fiber material (a component that accounts for 50% or more by mass; the same applies below). In particular, when the total of the first fiber material and the second fiber material is taken as 100% by mass, the proportion of the first fiber material is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably substantially all is the first fiber material (95% by mass or more is the first fiber material).

[0024] The first fiber material is not particularly limited as long as it has a crosslinkable portion, and one or more of materials that are known to be usable for this type of application can be appropriately used. The first fiber material preferably contains organic fibers because it has many crosslinkable portions. The first fiber material is preferably mainly composed of organic fibers. The first fiber material may be composed of organic fibers. The first organic fibers may be natural fibers or chemically synthesized chemical fibers (artificial fibers). Examples of natural fibers include plant fibers such as pulp fibers, animal fibers, and mineral fibers. The chemical fibers may be regenerated fibers, semi-synthetic fibers, or synthetic fibers. Examples of chemical fibers include aramid fibers, cellulose fibers, polyester fibers, polyethylene fibers, polypropylene fibers, acrylic fibers, rayon fibers, polyamide fibers, polyimide fibers, and polylactic acid fibers. Among them, at least one of aramid fibers and cellulose fibers is preferable from the viewpoints of durability, versatility, and ease of availability, and aramid fibers having nitrogen atoms are more preferable from the viewpoint of exerting the effects of the technology disclosed herein at a higher level.

[0025] However, the first fiber material may be an inorganic fiber as long as it has a crosslinkable site. Examples of inorganic fibers include glass fibers, metal fibers, ceramic fibers, and carbon fibers.

[0026] Although not particularly limited, the average length of the fiber material is typically preferably 0.01 μm to 30 mm. The average diameter of the fiber material is typically preferably 1 nm to 0.1 mm. The aspect ratio of the fiber material (ratio of average length to average diameter (average length / average diameter)) is generally 10 or more, for example, 100 or more, preferably 1000 or more. The average length and average diameter can be number average values ​​of a plurality of fiber materials obtained by measurement based on electron microscope observation.

[0027] In the first slurry preparation step (step S13), the initial liquid prepared in the initial liquid preparation step (step S11) and the first raw solution prepared in the first raw solution preparation step (step S12) are mixed to obtain a first slurry. In this embodiment, the first raw solution is added to a reaction tank containing the initial liquid and mixed. In this step, from the viewpoint of sufficiently fixing the metal ions to the fiber material, it is preferable to stir the mixed liquid in the reaction tank for a predetermined time. For stirring and mixing, a conventionally known stirring and mixing device as described above can be appropriately used. The temperature environment of this step is preferably the same as or higher than that of the initial liquid preparation step (step S11), for example, preferably 10°C or higher, and more preferably 20°C or higher. On the other hand, from the viewpoint of suppressing the volatilization of the solvent, it is preferably 40°C or lower, and more preferably 30°C or lower. It is preferable to perform stirring and mixing until the first slurry becomes homogeneous. The stirring and mixing time is not particularly limited since it may vary depending on, for example, the concentration of the metal ions in the first slurry, but is preferably 10 minutes or more, more preferably 30 minutes, from the viewpoint of sufficiently fixing the metal ions to the fiber material, while being preferably 120 minutes or less, more preferably 60 minutes or less, from the viewpoints of productivity, work efficiency, etc.

[0028] Fig. 2(A) is a schematic diagram of a first slurry. As shown in Fig. 2(A), the first slurry contains at least metal ions and a fibrous material. The fibrous material contains sites (crosslinkable sites) that can be crosslinked with the metal ions. Therefore, in the first slurry, the metal ions are captured by the crosslinkable sites of the fibrous material, and at least a portion of the metal ions are fixed (bonded) to the crosslinkable sites.

[0029] The second preparation step (step S20) is a step of mixing the first slurry prepared in the first preparation step (step S10) with an organic ligand source to obtain a second slurry. When the organic ligand source is in a powder, sol, gel, or other form, it is preferable to dissolve it in a solvent in advance. Therefore, in this embodiment, this step includes a second raw material solution preparation step (step S21) of mixing the organic ligand source with a solvent to prepare a second raw material solution, and a second slurry preparation step (step S22) of mixing the first slurry containing metal ions and a fiber material with the second raw material solution containing the organic ligand source to obtain a second slurry. Note that this step may further include other steps at any stage.

[0030] In the second raw solution preparation step (step S21), the organic ligand source and the solvent are mixed to prepare the second raw solution. For mixing, a conventionally known stirring and mixing device as described above can be appropriately used. Mixing is preferably performed until the second raw solution becomes homogeneous. The temperature environment of this step is preferably 10°C or higher, more preferably 20°C or higher, from the viewpoint of increasing the solubility of the organic ligand source. On the other hand, from the viewpoint of suppressing the volatilization of the solvent, it is preferably 40°C or lower, more preferably 30°C or lower. As the solvent, one or more of the media exemplified as those usable for the initial liquid can be appropriately used. The solvent is preferably one that can dissolve the organic ligand source. The solvent is typically an organic solvent (e.g., a lower alcohol). The solvent may be the same as or different from the initial liquid or the first raw solution of the first slurry. The solvent is preferably compatible with the first slurry to be mixed.

[0031] The organic ligand source contains at least an organic ligand constituting the metal organic framework. As the organic ligand source, one or more of those that have been conventionally known to be usable for this type of application can be appropriately used.

[0032] The organic ligand is an organic compound that has two or more sites capable of forming coordinate bonds with metal ions in the molecule and forms a lattice structure of the metal organic framework by bonding with the metal ions in the second slurry preparation step (step S22) described later. The organic ligand is not particularly limited, and depending on the type of metal ion, the molecule to be captured, etc., one or more compounds that have been known to be usable for this type of application, such as aromatic compounds, aliphatic compounds, alicyclic compounds, heterocyclic compounds, etc., can be appropriately used. Specific examples of the organic ligand include pyridines, pyrazines, pyrimidines, triazines, pyrazoles, imidazoles, triazoles, tetrazoles, dicarboxylic acids, tricarboxylic acids, and derivatives thereof. Among them, basic compounds are preferred. Since metal ions are typically electron acceptors, the lattice structure of the metal organic framework can be favorably grown in the second slurry preparation step by using a basic compound that is an electron donor.

[0033] The organic ligand is preferably an aromatic compound, more preferably an aromatic compound composed of the elements C, H, and N, and particularly preferably a heterocyclic aromatic compound containing one or two nitrogen atoms in the aromatic ring. For example, pyridines (pyridine and bipyridine) having a pyridine skeleton and pyrazines (e.g., pyrazine) having a pyrazine skeleton are preferred. A specific example is 4,4'-bipyridine. These compounds have a lone pair of electrons that the nitrogen atom can donate to a metal ion, which contributes to good compatibility and favorable growth of the metal organic framework. Therefore, the metal organic framework synthesized using these organic ligands exhibits good adsorption properties.

[0034] The second raw material solution is a solution in which an organic ligand of an organic ligand source is dissolved in a solvent. As an example, when the organic ligand is a pyridine (e.g., 4,4'-bipyridine) and the solvent is an alcohol (e.g., ethanol), the second raw material solution is a solution in which the pyridine as an organic ligand is dissolved in the alcohol as a solvent. The concentration of the organic ligand in the second raw material solution is not particularly limited because it may vary depending on, for example, the concentration of the metal ion in the first slurry, but is preferably 0.1 to 2 mol / L, more preferably 0.5 to 1.5 mol / L, and even more preferably 0.9 to 1 mol / L.

[0035] In the second slurry preparation step (step S22), the first slurry prepared in the first slurry preparation step (step S13) and the second raw solution prepared in the second raw solution preparation step (step S21) are mixed to obtain a second slurry. In this embodiment, a second raw solution containing an organic ligand source is added to a reaction tank containing the first slurry and mixed. In this step, it is preferable to stir the mixed solution in the reaction tank for a predetermined time. For stirring and mixing, a conventionally known stirring and mixing device such as that described above can be appropriately used. The temperature environment of this step is preferably the same as or higher than that of the first slurry preparation step (step S13), and is preferably 10°C or higher, and more preferably 20°C or higher. On the other hand, from the viewpoint of suppressing the volatilization of the solvent, it is preferably 40°C or lower, and more preferably 30°C or lower. It is preferable to perform the stirring and mixing until the second slurry becomes homogeneous. The stirring and mixing time is not particularly limited because it may vary depending on, for example, the type of metal organic framework to be generated, but is preferably 1 hour or more, and more preferably 10 hours or more. On the other hand, from the viewpoint of productivity, work efficiency, etc., 48 hours or less is preferable, and 24 hours or less is more preferable.

[0036] In addition, various additives that have been known to be usable for this type of application may be appropriately added to the second slurry as long as the effect of the technology disclosed herein is not significantly impaired. As various additives, one or more additives that have been known to be usable for this type of application may be appropriately used for the purpose of improving various properties of the molded body, such as improving mechanical strength and durability. Specific examples of additives include inorganic additives such as inorganic fillers and inorganic binders, and organic additives such as antioxidants, dispersants, flocculants, preservatives, stabilizers, and colorants (pigments, dyes, etc.). The proportion of these additives is preferably 10% by mass or less, more preferably 5% by mass or less, 3% by mass or less, 2% by mass or less, and 1% by mass or less, when the entire second slurry is taken as 100% by mass.

[0037] The second slurry preferably does not contain an organic binder as described in Patent Document 1, for example. This makes it difficult for the structural change of the metal-organic framework having structural flexibility to be hindered, and the structural flexibility can be favorably maintained, so that the performance of the molded body (for example, the adsorption performance when used as an adsorbent) can be maximized. In this specification, "does not contain" means that the proportion in the second slurry is approximately 1 mass % or less, preferably 0.1 mass % or less.

[0038] FIG. 2(B) is a schematic diagram of the second slurry. As described above, the first slurry contains a complex in which metal ions are fixed (bonded) to crosslinkable sites of the fiber material. The second raw material solution contains an organic ligand. As shown in FIG. 2(B), the organic ligand bonds with the metal ion to form a lattice structure of the metal organic framework. As a result, a metal organic framework containing the metal ion and the organic ligand is generated from the second slurry and disposed around the fiber material. In this embodiment, the metal organic framework contains copper ions (Cu 2+ ) as an organic ligand and tetrafluoroboric acid ([BF 4 ] - ) and having the formula: Cu(bpy)(BF 4 ) 2 (H2 O) 2 bpy; where bpy is 4,4'-bipyridine.

[0039] The forming step (step S30) is a step of forming the second slurry prepared in the second preparation step (step S20) to obtain a formed body in which the metal-organic framework is supported on a substrate made of a fiber material. In this embodiment, this is a step of forming the second slurry into a sheet by a wet papermaking method. This forms a sheet-like formed body. The wet papermaking method can realize a more homogeneous sheet-like formed body. This step can be performed, for example, by using a conventionally known papermaking machine. In this embodiment, this step includes a papermaking step (step S31) and a drying step (step S32). This step may further include other steps at any stage. For example, a washing step may be included before, during, or after the dehydration step (step S31).

[0040] In the dehydration step (step S31), the solvent contained in the second slurry is roughly removed, and the solid content in the second slurry is made into a sheet (formed). In one example, a papermaking machine is used to first perform papermaking by filtration and primary dehydration. The conditions for papermaking and filtration may be the same as those in the past. In the drying step (S32), the solvent is further removed from the wet paper obtained in the dehydration step (step S31). It is preferable to remove the solvent in multiple stages. For example, dehydration by pressing may be performed, followed by drying. The method and conditions for pressing and drying are not particularly limited and may be the same as those in the past. The drying temperature is preferably determined taking into consideration the boiling point of the solvent contained in the second slurry. For example, when the solvent contains water and alcohol, the temperature is preferably 50°C or higher, more preferably 70°C or higher.

[0041] By removing the solvent in this step, a molded body in which the metal organic framework is supported on the substrate containing the fiber material can be obtained. In the molded body produced in this embodiment, the metal organic framework is firmly fixed to the substrate via the crosslinkable site of the fiber material. The molded body of this embodiment has a function of selectively capturing a desired component from, for example, a fluid composition or the environment by being provided with the metal organic framework, and can be suitably used as an adsorbent, an occlusion material, a separation material, or the like. The molded body of this embodiment can be suitably used, for example, in a gas adsorption device or a gas separation device that adsorbs and separates a specific gas component from a mixed gas.

[0042] The sheet-like molded product obtained above can be further molded into various shapes such as a corrugated shape, a honeycomb shape, a slit shape, a pleated shape, a roll shape, etc., and used for various applications. By processing the sheet-like molded product into the above shapes, the contact area per unit volume with the object of separation (e.g., gas) can be increased, and the performance of the molded product can be improved.

[0043] FIG. 3(A) is a perspective view of the adsorption filter 100, and FIG. 3(B) is a front view of the adsorption filter 100. The adsorption filter 100 is configured to include the sheet-like molded body obtained above. As shown in FIG. 3(A), the adsorption filter 100 has a cylindrical outer shape in this embodiment. However, the outer shape of the adsorption filter 100 is not limited to a cylindrical shape, and can be various shapes in other embodiments. As shown in FIG. 3(B), the adsorption filter 100 includes a molded body 10 in which the above-mentioned sheet-like molded body is molded into a corrugated (wave-shaped) or pleated shape. The adsorption filter 100 can be used, for example, to purify exhaust gas discharged from the engine of a motorcycle, a generator, or the like.

[0044] In the manufacturing method disclosed herein, first, in a first preparation step, a first slurry containing metal ions and a fiber material containing a crosslinkable site is prepared. As a result, as shown in FIG. 2(A), for example, the metal ions are fixed (bonded) to the crosslinkable site. Next, in a second preparation step, an organic ligand is added, so that a lattice structure of the metal organic framework grows around the fiber material, as shown in FIG. 2(B), for example. This allows the metal organic framework to be more firmly supported on the fiber material (substrate). This can increase the unity between the fiber material and the metal organic framework, and prevent the metal organic framework from falling off the fiber material (substrate). Furthermore, since the metal organic framework can be more firmly supported on the substrate, it is possible to eliminate the use of an organic binder or reduce the amount of organic binder used.

[0045] In this embodiment, in the molding process, a sheet-like molded body is molded. This makes it possible to realize a molded body that is thinner and lighter than, for example, a pellet-like molded body or an extrusion molded body, and furthermore, a large surface area can be secured. In addition, since it is easy to mold into various shapes even after being made into a sheet, the range of uses and shapes can be expanded.

[0046] In this embodiment, the first preparation step to the molding step are performed in-line. For example, in the second preparation step, the organic ligand source is added to the first slurry and mixed. This can reduce the labor and improve productivity and work efficiency compared to, for example, a case where the slurry is lined out or transported to another facility.

[0047] In the present embodiment, in the forming step, the second slurry is formed into a sheet by a wet papermaking method, which not only improves productivity and work efficiency but also makes it possible to realize a more homogeneous sheet-like formed body.

[0048] In this embodiment, in the first preparation step, a fiber material having a functional group containing at least one of a hydroxyl group and a nitrogen atom as a site capable of crosslinking with the metal ion is used. For example, at least one of aramid fiber and cellulose fiber is used as the fiber material. This makes it easier for the metal ion of the metal organic framework to be strongly bonded to the fiber material (substrate), and the metal organic framework can be more firmly supported on the substrate.

[0049] In this embodiment, in the first preparation step, a metal ion source containing at least one of K, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Cr, W, Mo, Mn, Fe, Co, Ni, Cu, Ag, Zn, Cd, Al, Ga, In, and Sn is used as the metal ion. For example, a metal ion source containing an ion of a transition metal having a valence of 2 to 4 is used as the metal ion. For example, a metal ion source containing Cu ions is used. These metals tend to bond strongly to the fiber material in the first slurry. In addition, since the complex formation rate is high, the lattice structure of the metal-organic framework can be favorably grown in the second preparation step.

[0050] In this embodiment, in the second preparation step, an organic ligand source containing a basic compound is used as the organic ligand. Since metal ions are typically electron acceptors, the lattice structure of the metal-organic framework can be favorably grown in the second slurry preparation step by using a basic compound that is an electron donor.

[0051] In this embodiment, in the second preparation step, an organic ligand source containing 4,4'-bipyridine is used as the organic ligand. Compounds containing nitrogen atoms such as 4,4'-bipyridine have a lone pair of electrons that can be donated to metal ions, and therefore contribute to good compatibility and favorable growth of the metal organic framework. Therefore, the metal organic frameworks synthesized using these organic ligands exhibit good adsorption properties.

[0052] In this embodiment, in the second preparation step, the second slurry does not contain an organic binder. This makes it difficult for the structural change of the metal organic framework having structural flexibility to be hindered, and the structural flexibility can be favorably maintained, so that the performance of the molded body (for example, the adsorption performance when used as an adsorbent) can be maximized. In addition, since the surface of the metal organic framework is not covered with the organic binder, the contact area between the target of separation (for example, gas) and the metal organic framework can be increased, and the performance of the molded body (for example, the adsorption performance when used as an adsorbent) can be better exhibited.

[0053] In the present embodiment, in the forming step, the sheet-like molded body is further molded into a corrugated, honeycomb, slit, pleated, or roll shape, which increases the contact area per unit volume with the object of separation (e.g., gas), thereby enabling the molded body to exhibit better performance.

[0054] Examples of the present invention will be described below, but it is not intended that the present invention be limited to those shown in these examples.

[0055] In a comparative example, a metal organic framework was synthesized first, and then mixed with a fiber material to produce a molded body. That is, first, Cu(BF 4 ) 2 5.04 g of the aqueous solution was added, 73.82 g of purified water was added thereto, and the mixture was stirred and mixed for 10 minutes. Next, 2.99 g of 4,4'-bipyridine as an organic ligand source was added to a separate vessel, and 19.15 g of ethanol as a solvent was added thereto, and the mixture was stirred and mixed for 10 minutes. Next, the organic ligand source prepared in a separate vessel was added to the reaction vessel containing the metal ion source, and the mixture was stirred and mixed for 60 minutes to obtain a mixed solution. In this way, the metal organic framework was precipitated and generated in advance from the mixed solution.

[0056] Next, 1.4 g of aramid fiber as a fiber material and 500 g of water were added to another container, and the mixture was stirred and mixed for 5 minutes to prepare a slurry. This slurry was added to a reaction tank containing the metal-organic framework, and the mixture was stirred and mixed for 24 hours. The obtained slurry was then made into a sheet by a wet papermaking method. Specifically, the slurry after stirring and mixing for 24 hours was first suction filtered and made into a sheet (molded), then dehydrated with a press, and further dried on a hot plate at 80°C for 30 minutes. As a result, a sheet-like molded product was obtained.

[0057] In the examples, as shown in Fig. 1, a metal ion source and a fiber material were mixed first, and then an organic ligand source was added to produce a molded body. 4 ) 2 5.04 g of the aqueous solution was added, and 73.82 g of purified water was added thereto, and the mixture was stirred and mixed for 10 minutes. This prepared an initial solution. Next, 1.4 g of aramid fiber as a fiber material and 500 g of water were added to another container, and the mixture was stirred and mixed for 5 minutes to prepare a first raw material solution. Next, the first raw material solution prepared in another container was added to a reaction tank containing a metal ion source, and the mixture was stirred and mixed for 60 minutes to obtain a first slurry (first preparation step). This allowed the metal ions to be fixed (bonded) to the crosslinkable sites of the fiber material.

[0058] Next, 2.99 g of 4,4'-bipyridine was added as an organic ligand source to another container, and 19.15 g of ethanol as a solvent was added thereto, and the mixture was stirred and mixed for 10 minutes to prepare a second raw material solution. Next, the second raw material solution prepared in another container was added to the reaction tank containing the first slurry, and the mixture was stirred and mixed for 24 hours to obtain a second slurry (second preparation step). As a result, a metal-organic framework was precipitated and generated around the fiber material. The obtained slurry was then formed into a sheet by a wet papermaking method in the same manner as in the comparative example, to obtain a sheet-like molded body (molding step).

[0059] <Evaluation of Durability> The molded bodies of the comparative example and the example were evaluated for the fixation (resistance to falling off) of the metal-organic framework to the substrate by the following procedure. That is, first, the weight of the molded body was measured with an electronic balance to obtain the weight before the test. Next, the molded bodies of the comparative example and the example were separately placed in a beaker containing 50 ml of ethanol, and the beaker was placed in the bath of an ultrasonic cleaner. Note that a Bransonic tabletop ultrasonic cleaner (model: Bransonic (trademark) CPX5800-J, ultrasonic output: 160 W, oscillation frequency: 40 kHz) was used as the ultrasonic cleaner. Then, after ultrasonic treatment for 10 minutes, the beaker was taken out.

[0060] Fig. 4 is a photograph of the evaluation results for the Comparative Example and the Example. As shown in Fig. 4, in the beaker of the Comparative Example, the ethanol solution became very cloudy after the ultrasonic treatment, and it was observed that the metal-organic framework had fallen off from the substrate. On the other hand, in the beaker of the Example, the turbidity was relatively small even after the ultrasonic treatment, and it was observed that the metal-organic framework was firmly fixed to the substrate.

[0061] Next, the molded body was removed from the beaker, placed on a filter paper on a hot plate, and dried for about 20 minutes. The weight of the dried molded body was then measured with an electronic balance to obtain the weight after testing. The results are shown in Table 1 and Figure 5.

[0062] [Table 1]

[0063] In Table 1 and Fig. 5, the weight change before and after the test is considered to represent the amount of the metal organic framework that fell off from the molded body. As shown in Table 1 and Fig. 5, in the Examples, the weight change was relatively small compared to the Comparative Examples, and the amount of the metal organic framework that fell off was small. This suggests that the metal organic framework was relatively firmly supported (fixed) on the substrate. This result indicates the significance of the technology disclosed herein.

[0064] Although the preferred embodiments of the present invention have been described above, the above-described embodiments are merely examples, and the present invention can be embodied in various other forms. [Explanation of symbols]

[0065] 10 Molded body 100 Adsorption Filter S10 1st preparation step S20 2nd preparation process S30 Molding process

Claims

1. A method for producing a molded article comprising: a substrate containing a fiber material; and a metal organic framework supported on the substrate, the metal organic framework comprising a metal ion and an organic ligand, the method comprising the steps of: a first preparation step of mixing a metal ion source containing the metal ions forming the metal organic framework and a fiber material containing a site crosslinkable with the metal ions in a solvent to obtain a first slurry containing a complex in which the metal ions are bound to the crosslinkable sites of the fiber material; a second preparation step of mixing the first slurry with an organic ligand source containing the organic ligand that forms the metal-organic framework, thereby binding the organic ligand to the metal ion bound to the fiber material, and obtaining a second slurry in which the metal-organic framework containing the metal ion and the organic ligand is disposed around the fiber material; a molding step of molding the second slurry to obtain a molded body in which the metal-organic framework is supported on the base material containing the fibrous material; A method for producing a molded body, comprising the steps of:

2. In the molding step, a sheet-like molded body is molded. The method of claim 1 .

3. The steps from the first preparation step to the molding step are carried out in-line. The method according to claim 1 or 2.

4. In the second preparation step, the organic ligand source is added to the first slurry and mixed. The method according to claim 3.

5. In the forming step, the second slurry is formed into a sheet by a wet papermaking method. The method according to claim 3.

6. In the first preparation step, a fiber material having a functional group containing at least one of a hydroxyl group and a nitrogen atom as a site capable of crosslinking with the metal ion is used. The method according to claim 1 or 2.

7. In the first preparation step, at least one of aramid fiber and cellulose fiber is used as the fiber material. The method according to claim 6.

8. In the first preparation step, a metal ion source containing at least one of K, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Cr, W, Mo, Mn, Fe, Co, Ni, Cu, Ag, Zn, Cd, Al, Ga, In, and Sn is used as the metal ion. The method according to claim 1 or 2.

9. In the first preparation step, a metal ion source containing an ion of a transition metal having a valence of 2 to 4 is used as the metal ion. The method according to claim 1 or 2.

10. In the first preparation step, a metal ion source containing Cu ions is used. The method according to claim 1 or 2.

11. In the second preparation step, an organic ligand source containing a basic compound is used as the organic ligand. The method according to claim 1 or 2.

12. In the second preparation step, an organic ligand source containing 4,4'-bipyridine is used as the organic ligand. The method according to claim 1 or 2.

13. In the second preparation step, the second slurry does not contain an organic binder. The method according to claim 1 or 2.

14. In the forming step, the sheet-like molded body is further formed into a corrugated shape, a honeycomb shape, a slit shape, a pleated shape, or a roll shape. The method according to claim 2 .

15. In the first preparation step, a fiber material composed of organic fibers is used. The method according to claim 1 or 2.

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