Metal-organic framework dispersion production method, metal-organic framework dispersion, and metal-organic framework composition including metal-organic framework dispersion

Abstract

[Problem] To provide a method for using a mechanical pulverization technique to produce a dispersion comprising a nm-size metal-organic framework which has good dispersion stability while maintaining a crystal structure. [Solution] A metal-organic framework dispersion production method comprising: a step (1) for mixing a component (a), which is a solid powder of a metal-organic framework that contains metal ions and organic ligands coordinated to the metal ions, said metal ions being at least one type selected from the group consisting of Zr ions, Al ions, and Zn ions, a component (b), which is a dispersant and which is an aliphatic amine compound that is a primary amine, a secondary amine, or a tertiary amine having one amino group in a molecule thereof, and which is soluble in a dispersion medium (c1), and a component (c1), which is said dispersion medium; and a step (2) for using the obtained mixture to produce a dispersion via a mechanical pulverization technique (wherein in the mechanical pulverization technique, the crystal structure of the metal-organic framework (a) does not change, and the crystal structure of the solid powder is maintained).

Description

Method for producing a metal-organic structure dispersion, metal-organic structure dispersion, and metal-organic structure composition containing the metal-organic structure dispersion

[0001] The present invention relates to a method for producing a metal-organic framework (MOF) dispersion having excellent dispersion stability, a metal-organic framework dispersion, and a metal-organic framework composition containing the metal-organic framework dispersion.

[0002] Metal-organic frameworks are porous coordination compounds obtained by the self-assembly of metal ions and organic ligands that have sites for coordinating to the metal ions. The metal ions and organic ligands are periodically bonded by coordinate bonds, and the metal-organic frameworks have both inorganic and organic moieties. Due to their excellent porosity and ability to adsorb and desorb molecules into the pores, metal-organic frameworks are being investigated for a variety of applications, including gas separation membranes, gas storage, liquid adsorption, and catalysts.

[0003] The practical application of metal organic frameworks is mainly limited to tablets formed from powder, because the crystal size of metal organic frameworks is large on the order of μm due to crystal growth caused by rapid self-organization, and they also have the property of easily agglomerating.

[0004] It is generally difficult to dissolve metal-organic frameworks in solvents or polymers while maintaining their crystalline structure. Therefore, in recent years, studies have been conducted to prepare dispersions in which metal-organic frameworks are dispersed in solvents or polymers and use them as composite membranes. However, micrometer-order metal-organic frameworks tend to settle in the dispersions and easily aggregate, making the dispersion stability of the metal-organic framework an issue during composite formation. Poor dispersion stability results in an unstable dispersion state of the metal-organic framework, making handling difficult and resulting in unstable performance and membrane quality. Therefore, dispersion stability is both a major challenge and a very important factor for mass production. For example, in gas separation applications, when polymers and gas molecules are composited, aggregation of the metal-organic framework generates nonselective voids between the polymers, resulting in reduced gas selectivity (Patent Document 1). In addition, poor dispersion stability can lead to the generation of coarse particles due to aggregation of the metal-organic framework and poor dispersion of the metal-organic framework during the composition preparation process and membrane formation process, resulting in membrane defects and variations in properties.

[0005] In Patent Documents 1 and 2, when synthesizing a metal-organic framework by a solvothermal method, a large amount of chemical regulators or surfactants, approximately equal to the amount of raw materials, is added to inhibit crystal growth, thereby obtaining a metal-organic framework powder with a small size on the order of nanometers. However, these documents do not describe the dispersion stability of the obtained powder. Therefore, it is unclear whether the powder maintains a good dispersion state even after film-forming processes such as dispersion preparation, composition preparation, and coating and heating the composition to dry it. Furthermore, since the solvothermal method involves a large amount of additives and raw materials, preparing a dispersion often requires a process of removing raw materials and additives, such as reprecipitation or filtration, followed by a process of redispersing the material in a solvent or the like. Therefore, this method has issues with manufacturing process costs.

[0006] Patent Document 3 reports that a composite composition can be obtained by coexisting a matrix polymer when preparing a metal-organic framework by solid-phase synthesis, but does not specifically disclose dispersion stability. Methods for obtaining a metal-organic framework dispersion include mixing a metal-organic framework powder with a resin or a solvent and using an ultrasonic homogenizer, a planetary stirring and degassing device, or the like to alleviate the aggregation state of the metal-organic framework and obtain a dispersion, and using a mechanical pulverization method such as a ball mill or a bead mill to alleviate the aggregation state and obtain a dispersion. However, mechanical pulverization methods such as a ball mill or a bead mill create conditions that generate strong physical forces and shear stress, which can cause the crystal structure of the metal-organic framework to break down (Patent Document 4).

[0007] JP 2021-526962 A JP 2018-118929 A JP 2021-523823 A JP 2019-56055 A

[0008] In order to improve the dispersion stability of a metal-organic framework dispersion, it is necessary to reduce the primary particle size of the metal-organic framework. To reduce the primary particle size by a mechanical pulverization method, a stronger stress is required than the stress required to break up the aggregated state of the primary particles, which causes a problem of changing the crystal structure of the metal-organic framework. Therefore, it is expected that there is a trade-off between dispersion stability and maintaining the crystal structure.

[0009] An object of the present invention is to obtain a metal-organic framework dispersion liquid having good dispersion stability, and a metal-organic framework composition containing the metal-organic framework dispersion liquid. In addition, when a solid powder of a metal-organic framework is mechanically pulverized to reduce the crystal size and prepare a dispersion liquid, it is necessary to maintain the crystalline structure of the metal-organic framework in terms of characteristics. However, there is a problem that the crystalline structure of the metal-organic framework changes due to mechanical pulverization.

[0010] To solve the above problems and obtain a dispersion with good dispersion stability, the inventors focused on the crystal size of the metal-organic framework and attempted to reduce the size from μm to nm. However, mechanical milling techniques that impart weak shear stress did not reduce the crystal size, while mechanical milling techniques such as ball mills and bead mills that impart strong shear stress reduced the crystal size but changed the crystal structure. The inventors discovered that adding an appropriate dispersant to a ball mill or bead mill can reduce the crystal size without changing the crystal structure of the metal-organic framework. Furthermore, they discovered that even after reducing the crystal size, the metal-organic framework can be prevented from aggregating by appropriately creating a combination of metal ions and organic ligands that constitute the metal-organic framework, as well as the selection and combination of a dispersant and a dispersion medium. That is, the inventors discovered an appropriate mechanical milling technique, metal-organic framework, dispersant, and dispersion medium, and completed the invention.

[0011] That is, the present invention is a method for producing a metal organic framework dispersion liquid, comprising: (a) component: a solid powder of a metal organic framework containing metal ions and organic ligands coordinated to the metal ions, wherein the metal ions are at least one selected from the group consisting of Zr ions, Al ions, and Zn ions; (b) component: a dispersant, which is a primary amine, secondary amine, or tertiary amine having one amino group represented by the following formula (1) in the molecule, and (c1) an aliphatic amine compound having solubility in a dispersion medium; (In the formula, R １ and R ２ each independently represent a hydrogen atom or an aliphatic hydrocarbon group, and * represents a bond to a carbon atom.) A method for producing a metal organic framework dispersion liquid, comprising: a step (1) of mixing a component (c1): a dispersion medium with a (c2) component; and a step (2) of producing a dispersion liquid by a mechanical pulverization method using the obtained mixture (provided that the mechanical pulverization method is performed on the condition that (a) the crystalline structure of the metal organic framework does not change and the crystalline structure of the solid powder is maintained).

[0012] a Z-average particle size of the solid powder of the metal-organic framework in the metal-organic framework dispersion liquid is 10 nm or more and less than 1000 nm, and a settling velocity of the solid powder particles of the metal-organic framework in an environment of a centrifugal force of 470 G or less is 100 μm / s or less.

[0013] a step (3) of mixing the metal-organic framework dispersion liquid with at least one of a dispersion medium (c2) component different from the dispersion medium (c1) component in the dispersion liquid and an additive (d) component.

[0014] the organic ligand is at least one selected from the group consisting of fumaric acid, terephthalic acid, isophthalic acid, 2-aminoterephthalic acid, 2-methylimidazole, and dicarboxypyrazole.

[0015] The method for producing a metal organic framework dispersion, wherein the metal organic framework is MIL-53, CAU-10, ZIF-8, MOF-801, MOF-303, UiO-66, or UiO-NH2-66.

[0016] The method for producing a metal organic framework dispersion, wherein the mechanical pulverization method is a pulverization method using a ball mill or a bead mill.

[0017] the ball mill or bead mill has a ball diameter or bead diameter of 0.01 mm or more and 10 mm or less, and the material of the balls or beads is at least one selected from the group consisting of metal and glass.

[0018] (a) component: a solid powder of a metal organic framework containing metal ions and organic ligands coordinated to the metal ions, wherein the metal ions are at least one selected from the group consisting of Zr ions, Al ions, and Zn ions; (b) component: as a dispersant, a primary amine, secondary amine, or tertiary amine having one amino group represented by the following formula (1) in the molecule, and (c1) an aliphatic amine compound having solubility in a dispersion medium; (In the formula, R １ and R ２each independently represent a hydrogen atom or an aliphatic hydrocarbon group, and * represents a bond to a carbon atom.) A dispersion comprising a component (c1): a dispersion medium, wherein the Z-average particle size of a solid powder of the metal-organic framework in the dispersion is 10 nm or more and less than 1000 nm, and the settling velocity of the solid powder particles of the metal-organic framework in an environment of a centrifugal force of 470 G or less is 100 μm / s or less.

[0019] The metal organic framework dispersion liquid, wherein the organic ligand is at least one selected from the group consisting of fumaric acid, terephthalic acid, isophthalic acid, 2-aminoterephthalic acid, 2-methylimidazole, and dicarboxypyrazole.

[0020] A metal-organic framework dispersion, wherein the metal-organic framework is MIL-53, CAU-10, ZIF-8, MOF-801, MOF-303, UiO-66, or UiO-NH2-66.

[0021] A metal organic framework composition comprising the metal organic framework dispersion liquid, and at least one of a dispersion medium (c2) component different from the dispersion medium (c1) component in the dispersion liquid, and an additive (d) component.

[0022] According to the method for producing a metal-organic framework dispersion of the present invention, it is possible to provide a method for producing a metal-organic framework dispersion or the like having excellent dispersion stability without changing the crystalline structure of the metal-organic framework. According to the present invention, the metal-organic framework dispersion and the metal-organic framework composition containing the metal-organic framework dispersion have the effect of exhibiting excellent dispersion stability without changing the crystalline structure of the metal-organic framework. According to the present invention, the metal-organic framework dispersion has the effect of exhibiting excellent dispersion stability in which the Z-average particle diameter of the solid powder of the metal-organic framework is 10 nm or more and less than 1,000 nm, and the settling velocity of the solid powder particles of the metal-organic framework is 100 μm / s or less in an environment of a centrifugal force of 470 G or less.

[0023] Fig. 1 shows X-ray diffraction patterns showing the results of crystal structure analysis of the powder of Production Example 1, the powder obtained from the dispersion of Example 1, and the powder obtained from the dispersion of Comparative Example 1. Fig. 2 shows photographs of the results of SEM-EDX analysis of the powder of Production Example 1, the powder obtained from the dispersion of Example 1, and the powder obtained from the dispersion of Comparative Example 1. Fig. 3 shows X-ray diffraction patterns showing the results of crystal structure analysis of the powder of Production Example 2, the powder of Production Example 3, the powder obtained from the dispersion of Example 11, and the powder obtained from the dispersion of Example 15.

[0024] The method for producing a metal-organic framework dispersion liquid, the metal-organic framework dispersion liquid, and the metal-organic framework composition containing the metal-organic framework dispersion liquid of the present invention are described below. <Metal-organic framework> The metal-organic framework is a crystalline porous material composed of metal ions and organic ligands coordinated to the metal ions. The metal ions are ions of at least one metal selected from the group consisting of Mg, V, Cr, Nb, Mo, Zr, Hf, Mn, Fe, Co, Cu, Ni, Zn, Cd, Ru, Al, Ti, V, and Ga. Among these metal ions, Zr ions, Al ions, and Zn ions are preferred, and Zr ions and Al ions are more preferred from the viewpoint of structural stability against water. Component (a) of the present invention is a solid powder of a metal-organic framework.

[0025] <Organic Ligand> The organic ligand is a compound having two or more functional groups (coordinating functional groups) capable of coordinating to a metal ion. Examples of the coordinating functional group include a carboxyl group, a pyridinyl group, a cyano group, an amino group, a sulfonyl group, a porphyrinyl group, an acetylacetonate group, a hydroxyl group, a Schiff base, an amino acid residue, and the like. The coordinating functional group is preferably one that can form a strong coordinate bond with a metal ion. The organic ligand can preferably have two or more coordinating functional groups at any position of the organic ligand. An organic ligand having a coordinating functional group at its terminal is preferred from the viewpoints of easily controlling the structure of the metal-organic framework and obtaining a metal-organic framework having relatively large pores. The organic ligand includes, but is not limited to, oxalic acid, malonic acid, succinic acid, glutaric acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, citric acid, trimesic acid, squaric acid, imidazole, pyrazole, diazole, triazole, tetrazole, azole, and mixtures thereof. Among these organic ligands, at least one selected from the group consisting of fumaric acid, terephthalic acid, isophthalic acid, 2-aminoterephthalic acid, 2-methylimidazole, and dicarboxypyrazole is preferred in order to easily control the structure of the metal organic framework and to obtain a metal organic framework having relatively large pores.

[0026] <Dispersant, Component (b)> Examples of dispersants include aliphatic amine compounds such as primary amines, secondary amines, or tertiary amines having one amino group in the molecule. The aliphatic amine compounds described in the present invention are soluble in components (c1) and (c2). Aliphatic amines include primary amines, secondary amines, and tertiary amines. Examples of primary amines include saturated aliphatic monoamines having a linear aliphatic hydrocarbon group, such as propylamine, butylamine, hexylamine, pentylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine (aminoundecane), dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, and octadecylamine. In addition to the linear aliphatic amines described above, examples of saturated aliphatic amines include branched aliphatic amines such as isohexylamine, 2-ethylhexylamine, and tert-octylamine. Other examples include unsaturated aliphatic amines such as cyclohexylamine and oleylamine. In addition to these aliphatic amines, primary amines also include amines in which hydrogen atoms are substituted with hydroxyl groups, such as propanolamine. Examples of secondary amines include linear amines such as dipropylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, octylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ethylmethylamine, methylpropylamine, ethylpropylamine, and propylbutylamine. Examples of branched secondary amines include diisohexylamine and di(2-ethylhexyl)amine. In addition to these aliphatic amines, secondary amines also include amines in which hydrogen atoms are substituted with hydroxyl groups, such as methylaminoethanol. Examples of tertiary amines include tributylamine, tripentylamine, and trihexylamine. Examples of branched tertiary amines include triisohexylamine, tri(2-ethylhexyl)amine, and tridodecylamine. In addition to these aliphatic amines, tertiary amines also include those in which a hydrogen atom has been replaced with a hydroxyl group.In order to be suitable for use in a ball mill or a bead mill and to suppress changes in the crystal structure, the aliphatic amine (compound) should have one nitrogen atom, and the group bonded to the nitrogen atom should be a linear aliphatic hydrocarbon group having 1 to 15 carbon atoms, with a hydroxyl group being preferred as the substituent on the aliphatic hydrocarbon group.

[0027] <Dispersion medium, component (c1)> The aliphatic amines, including the primary amines, secondary amines, and tertiary amines, are soluble in the component (c1) of the dispersion medium of the present invention. Examples of the component (c1) include solvents, crosslinkable monomers, and polymers. These may be used alone or in combination of two or more. Specific examples of the component (c1) of the present invention are listed below, but are not limited to these examples as long as the effects of the present invention are not lost.Specific examples of the solvent include methanol, ethanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2 1,2-hexanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 2,3-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 1,7-hexanediol, 1,8-hexanediol, 1,9-hexanediol, 2,10-hexanediol, 2,11-hexanediol, 2,12-hexanediol, 2,13-hexanediol, 2,14-hexanediol, 2,15-hexanediol, 2,16-hexanediol, 2,17-hexanediol, 2,18-hexanediol, 2,19-hexanediol, 2,20-hexanediol, 2,21-hexanediol, 2,22-hexanediol, 2,23-hexanediol, 2,24-hexanediol, 2,25-hexanediol, 2,26-hexanediol, 2,27-hexanediol, 2,28-hexanediol, 2,29-hexanediol, 2,30-hexanediol, 2,31-hexanediol, 2,32-hexanediol, 2,33-hexanediol, 2,34-hexanediol, 2,35-hexanediol, 2,36-hexanediol, 2,37-hexanediol, 2,38-hexanediol, 2,3 ...9-hexanediol, 2,39-hexanediol, Examples of the solvent include amides such as dimethylacetamide and N-methyl-2-pyrrolidone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, xylene, methyl ethyl ketone, methyl isobutyl ketone, cycloheptanone, 4-methyl-2-pentanol, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, ethyl ethoxyacetate, 2-hydroxyethyl acetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, butyl lactate, 2-heptanone, methoxycyclopentane, and anisole. These may be used alone or in combination of two or more.Specific examples of the crosslinkable monomer include (meth)acrylate compounds, such as so-called glycol compounds, including polyethylene glycol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, polyethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, tripropylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, and mixtures thereof. Other (meth)acrylate compounds include, for example, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, glycerin dimethacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, dimethylol-tricyclodecane di ... Examples of the acrylate include difunctional (meth)acrylates such as methyloxypropyl methacrylate, trifunctional (meth)acrylates such as pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and pentaerythritol hexamethylene diisocyanate urethane prepolymer, tetrafunctional (meth)acrylates such as pentaerythritol tetraacrylate, and hexafunctional (meth)acrylates such as dipentaerythritol hexaacrylate, and mixtures thereof.

[0028] <Dispersion medium, component (c2)> The component (c2) of the present invention may be any compound that dissolves an aliphatic amine and is different from the component (c1). Examples of the component (c2) include solvents, crosslinkable monomers, and polymers, and can be added to adjust the solids concentration, viscosity, coatability, etc. of the resulting dispersion, or to adjust the strength of the film obtained by forming the dispersion into a film. Specific examples of the component (c2) of the present invention include those described as specific examples of the component (c1), but are not limited to these examples as long as the effects of the present invention are not lost.

[0029] <SP Value> The above-mentioned aliphatic amines, including primary amines, secondary amines, and tertiary amines, are soluble in the components (c1) and (c2) of the dispersion medium of the present invention. The inventors have confirmed that the solubility parameter (SP) values ​​of the components (c1) and (c2) of the dispersion medium serve as an indicator of this solubility. The SP values ​​of the dispersion mediums used in the examples of the present invention are shown in the column for component (c1) in the examples. Examples of dispersion mediums used in the examples of the present invention include methanol (MeOH) with an SP value of 30 and propylene glycol monomethyl ether acetate (PGMEA) with an SP value of 18. The SP value of the dispersion medium is not particularly limited as long as the effects of the present invention are not lost. However, from the viewpoint of dispersion stability, the SP value is in the range of 5 to 50, preferably in the range of 10 to 40, and more preferably in the range of 15 to 35.

[0030] <Component (d)> The component (d) of the present invention includes additives that are generally added as needed, such as inorganic fillers, leveling agents, polymerization initiators, polymerization inhibitors, photosensitizers, adhesion promoters, plasticizers, UV absorbers, conductive agents, and pigments. These may be appropriately blended alone or in combination of two or more kinds, as long as the effects of the present invention are not impaired.

[0031] <Steps (1), (2), and (3)> Step (1) is a step of mixing component (a), component (b), and component (c1). Step (2) is a step of producing a metal-organic framework dispersion from the mixture mixed in step (1) by the mechanical grinding method described below, on the condition that the crystal structure (crystalline state) of the metal-organic framework of component (a) does not change and maintains the crystal structure (crystalline state). Step (3) is a step of producing a metal-organic framework composition by mixing the metal-organic framework dispersion produced in step (2) with at least one of component (c2) and component (d).

[0032] <Mechanical Pulverization Method> To mechanically pulverize a metal-organic framework in a dispersion medium and obtain a dispersion in which the crystal size of the metal-organic framework is reduced from μm to nm, techniques such as agitation blades, ultrasonic stirring, homogenizers, ultrasonic homogenizers, hammer mills, vibration mills, and high-speed rotary grinders can be used. However, when obtaining a dispersion, stirring techniques that generate strong physical forces or shear forces may cause changes in the crystals of the metal-organic framework, resulting in undesirable results. Here, one object of the present invention is to obtain a metal-organic framework of nm size without changing the crystals of the metal-organic framework and while maintaining the crystal structure. Therefore, in the present invention, a ball mill and a bead mill were used, which are capable of adjusting the material, size, and number of media placed in a container, as well as the rotation speed and rotation time of the container, and are therefore capable of suppressing changes in the crystals of the metal-organic framework. Furthermore, in the present invention, changes in the crystals of the metal-organic framework were suppressed by selecting an appropriate dispersant other than the metal-organic framework placed in the container of the ball mill and the bead mill.

[0033] <Pulverization by Ball Mill / Bead Mill> One of the mechanical pulverization techniques used in the present invention is a ball mill and a bead mill. The difference between a ball mill and a bead mill is the mechanism of rotational movement: in a ball mill, the container rotates on its axis, while in a bead mill, the mixer inside the container rotates. The media placed in both containers are the same, and the rotation speed and rotation time can be adjusted. Therefore, similar effects can be expected whether either technique is used. Materials for the media in ball mills and bead mills include (high) alumina, natural silica, silicon carbide, silicon nitride, glass, iron-cored nylon, zirconia, stainless steel, steel, carbon steel, and chromium steel. From the viewpoint of not changing the crystal structure of the metal-organic framework even when subjected to a mechanical pulverization technique, media sizes of 0.01 mm or more and 10 mm or less in diameter can be used. From this viewpoint, preferred sizes include diameters of 0.03 mm to 5.0 mm, and more preferably 0.1 mm to 2.0 mm.

[0034] <Ultrasonic Pulverization> One of the mechanical pulverization techniques used in the present invention is ultrasonic treatment. The equipment and treatment conditions used in the present invention are as follows: Ultrasonic generator: Ultrasonic cleaner (US CLEANER) manufactured by AS ONE Corporation Frequency: 40 kHz

[0035] <Z-average particle size> In the present invention, the Z-average particle size of the solid powder of the metal-organic framework can be calculated, for example, by dynamic light scattering. Specifically, for example, the metal-organic framework dispersion is placed in a measurement cell, irradiated with light, and the Z-average particle size can be calculated from the solution viscosity and temperature based on the principle of Brownian motion. In order to obtain good dispersion stability, the Z-average particle size is preferably less than 1000 nm, more preferably 800 nm or less, or 600 nm or less. The apparatus and measurement conditions used in the present invention are shown below. Apparatus: Malvern Zetasizer NanoZS, Spectris Inc. Measurement conditions: backscattering (angle 173°) Measurement temperature: 25°C Measurement concentration: 0.005 mass% Measurement position: 4.2 mm Viscosity parameters: viscosity of each dispersion medium at 25°C is used

[0036] <Settling velocity> In the present invention, the settling velocity of solid powder particles of the metal-organic framework was measured using a centrifugal settling device. The settling velocity of the particles was calculated by forcibly settling the particles using the centrifugal force of the device and optically capturing and analyzing the change. The analysis conditions were to calculate the settling velocity using the change over time in the cell position at which the transmittance reached 50%. The device and measurement conditions used in the present invention are shown below. Device: Lumisizer manufactured by LUM Corporation Maximum rotation radius: 105 mm Rotation speed: 2000 rpm Centrifugal force: 470 G (calculated according to the following formula) Centrifugal force = (Rotation speed / 1000) ２ × maximum radius of rotation (mm) × 1.118 Measurement cell: Polyamide cell, optical path length 2 mm Measurement temperature: 25°C Analysis mode: Front Tracking

[0037] <Dispersion Stability> The lower the sedimentation rate, the better the dispersion stability. From the viewpoint of ease of handling and stable quality, a sedimentation rate of 100 μm / s or less under a centrifugal force of 470 G or less can be said to indicate good dispersion stability. For better dispersion stability, the sedimentation rate is 90 μm / s or less, preferably 80 μm / s or less, and more preferably 70 μm / s or less.

[0038] <Crystal Structure Analysis> In the present invention, an X-ray diffractometer (XRD) was used for crystal structure analysis. The measurement principle of an X-ray diffractometer is to analyze the diffraction that occurs as a result of X-rays being scattered and interfered by electrons around atoms when X-rays are irradiated onto a sample. Generally, by using this diffraction information, it is possible to identify and quantify the crystalline phase of a sample, analyze the degree of crystallinity, crystal size and distortion, and molecular structure. The equipment used in the present invention is shown below. Equipment: MiniFlex 600 manufactured by Rigaku Corporation

[0039] <SEM and SEM-EDX> In the present invention, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (SEM-EDX) were used for observing the crystalline state and for elemental analysis. SEM is a technique that can obtain contrast due to differences in the sample's surface roughness and composition based on information about electrons emitted from the sample when an electron beam is irradiated onto the sample. EDX is a technique that performs elemental analysis and composition analysis by detecting characteristic X-rays generated by electron beam irradiation and dispersing them by energy. EDX is attached to the SEM. The device used in the present invention is a high-performance field-emission scanning electron microscope that can obtain high resolution at an extremely low acceleration voltage of 1 kV or less in order to observe information about the sample's surface. The device and measurement conditions used in the present invention are as follows: Device: JEOL Ltd. JSM-7400F Acceleration voltage: SEM 1.0 kV, SEM-EDX 5.0 kV Emission current: 10 μA

[0040] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. <Metal-organic framework solid powder> The solid powder of the metal-organic framework used in the present invention is shown together with its abbreviation. [Production Example 1] Production of MOF-801 A 500 ml four-neck flask was charged with 11.1 g (34.5 mmol) of zirconium chloride octahydrate as the metal component, 4.00 g (34.5 mmol) of fumaric acid as the organic ligand, 38.9 ml of formic acid as the catalyst, and 110.1 ml of dimethylformamide as the solvent. After dissolving the zirconium chloride octahydrate and fumaric acid in the solvent, the reaction solution was heated to 130°C using an oil bath and reacted at 130°C for 24 hours. The white powder that precipitated in the reaction solution was collected on filter paper using Kiriyama filtration and washed with 300 ml of DMF and 300 ml of MeOH. The resulting metal-organic framework powder was then vacuum dried at 150°C for 5 hours. When the obtained powder was observed under an SEM, it was found to be a polyhedron shaped powder close to a sphere with a primary particle size of about 1 μm, which had secondary agglomerated to a size of about 5 to 50 μm.

[0041] [Production Example 2] Production of MOF powder UiO-NH2-66 A 500 ml four-neck flask was charged with 1.88 g (8.1 mmol) of zirconium chloride as the metal component, 2.04 g (11.3 mmol) of 2-amino-1,4-benzenedicarboxylic acid as the organic ligand, 7.5 ml of hydrochloric acid as the catalyst, and 150 ml of dimethylformamide as the solvent. After dissolving the zirconium chloride and 2-amino-1,4-benzenedicarboxylic acid in the solvent, the reaction solution was heated to 120 °C using an oil bath and reacted at 120 °C for 6 hours. The yellowish-white powder that precipitated in the reaction solution was collected on filter paper using Kiriyama filtration, washed with 300 ml of MeOH and 300 ml of acetone, and then vacuum-dried at 120 °C for 5 hours. Observation of the obtained powder with an SEM revealed that the primary particles were spherical with a size of about 0.6 to 1.0 μm, and secondary agglomerates had a size of about 20 to 50 μm.

[0042] [Production Example 3] Production of MOF powder MOF-303 A 1000 ml recovery flask was charged with 10.4 g (43.1 mmol) of aluminum chloride hexahydrate as the metal component, 7.50 g (43.1 mmol) of 3,5-pyrazoledicarboxylic acid monohydrate as the organic ligand, and 720 mL of water as the solvent. Aluminum chloride hexahydrate and 3,5-pyrazoledicarboxylic acid monohydrate were dissolved at room temperature. Thereafter, while stirring the reaction solution, a sodium hydroxide solution prepared by diluting 2.60 g of sodium hydroxide with 30 ml of water was added dropwise to the reaction solution. The reaction solution was heated to 100 °C using an oil bath and reacted at 100 °C for 24 hours. The white powder that precipitated in the reaction solution was collected on filter paper by filtration and washed with 500 ml of water and 500 ml of methanol. The resulting metal-organic framework powder was then vacuum dried at 70 °C for 9 hours, followed by vacuum drying at 150 °C for 9 hours. When the obtained powder was observed under an SEM, it was found that square columnar crystals with a primary particle size of about 50 to 150 nm had secondary agglomerated to form spherical particles of about 2 μm.

[0043] Other metal organic frameworks used in the present invention are shown with their abbreviations. MIL-53: Basolite (registered trademark) A100 (metal species: Al, organic ligand: terephthalic acid) [Sigma-Aldrich]. SEM observation revealed that the primary particle size was needle-shaped, with a length of approximately 1.0 to 1.5 μm and a width of approximately 15 to 30 nm, and secondary aggregates were spherical, with a size of approximately 20 to 40 μm. CAU-10: Aluminum hydroxide isophthalate MOF (metal species: Al, organic ligand: isophthalic acid) [Fujifilm Wako Pure Chemical Industries, Ltd.]. SEM observation revealed that the primary particle size was cubic, with a side length of approximately 3.0 to 7.0 μm. ZIF-8: Zinc 2-methylimidazole MOF (metal species: Zn, organic ligand: 2-methylimidazole) [Fujifilm Wako Pure Chemical Industries, Ltd.] SEM observation revealed that the primary particles were spherical with a size of approximately 0.2 to 0.3 μm, and the secondary aggregates were ellipsoidal with a size of approximately 10 μm. UiO-66: Zirconium 1,4-dicarboxybenzene MOF (metal species: Zr, organic ligand: 1,4-dicarboxybenzene) [Fujifilm Wako Pure Chemical Industries, Ltd.]

[0044] <Dispersant, Component (b)> The dispersants used in the present invention are shown below together with their abbreviations. AM-1: Tripentylamine [Tokyo Chemical Industry Co., Ltd.] AM-2: Propanolamine [Tokyo Chemical Industry Co., Ltd.] AM-3: Methylaminoethanol [Tokyo Chemical Industry Co., Ltd.] AM-4: 1-Aminoundecane [Tokyo Chemical Industry Co., Ltd.] AM-5: Tridodecylamine [Tokyo Chemical Industry Co., Ltd.] AM-6: Trimethylstearylammonium chloride [Tokyo Chemical Industry Co., Ltd.] AM-7: N,N-Bis(3-aminopropyl)ethylenediamine [Tokyo Chemical Industry Co., Ltd.] AM-8: 1,6-Diaminohexane [Tokyo Chemical Industry Co., Ltd.] AM-9: N,N,N',N'-Tetrakis(2-hydroxypropyl)ethylenediamine [Tokyo Chemical Industry Co., Ltd.] AM-10: Pyrrole [Tokyo Chemical Industry Co., Ltd.] AM-11: Pyridine [Tokyo Chemical Industry Co., Ltd.] AM-12: Aniline [Tokyo Chemical Industry Co., Ltd.] AC-1: Formic acid [Tokyo Chemical Industry Co., Ltd.] AC-2: Stearyl acid [Tokyo Chemical Industry Co., Ltd.] AC-3: Phosphanol RS-710 (Polyoxyethylene alkyl (12-15) ether phosphate) [Toho Chemical Industry Co., Ltd.]

[0045] <Component (c1)> The component (c1) used in the present invention is shown below with its abbreviation. DMF: N,N-dimethylformamide [Kanto Chemical Co., Ltd.], viscosity (25°C): 0.8 mPa·s, refractive index (25°C): 1.428, SP value: 25 (calculated using Winmostar (registered trademark)) MeOH: methanol [Kanto Chemical Co., Ltd.], viscosity (25°C): 0.5 mPa·s, refractive index (25°C): 1.329, SP value: 30 (calculated using Winmostar (registered trademark)) PGME: propylene glycol monomethyl ether [Tokyo Chemical Industry Co., Ltd.], viscosity (25°C): 1.9 mPa·s, refractive index (25°C): 1.404, SP value: 20 (calculated using Winmostar (registered trademark)) PGMEA: Propylene glycol monomethyl ether acetate [Tokyo Chemical Industry Co., Ltd.], viscosity (25°C): 1.1 mPa·s, refractive index (25°C): 1.404, SP value: 18 (calculated using Winmostar (registered trademark)) D-1: Polyethylene glycol diacrylate [Shin-Nakamura Chemical Co., Ltd. A-200], viscosity (25°C): 25 mPa·s, refractive index (25°C): 1.463, SP value: 19 (calculated using Winmostar (registered trademark)) D-2: 1,6-hexanediol diacrylate [Osaka Organic Chemical Industry Co., Ltd. Viscoat #230], viscosity (25°C): 7 mPa·s, refractive index (25°C): 1.456, SP value: 18 (calculated using Winmostar (registered trademark))

[0046] <Mechanical pulverization step> Method: ball mill The components listed in Table 1 were charged into a screw tube in a predetermined ratio. Then, balls serving as media were added to the screw tube until the volume was approximately half of the liquid volume. The screw tube was then stirred with a mix rotor at a rotation speed of 70 rpm for a predetermined time to perform a pulverization process. The media types used are hereinafter represented by the following abbreviations. M-1: Zirconia balls YTZ-1 (size: φ1 mm) manufactured by Nikkato Corporation M-2: Zirconia balls YTZ-0.2 (size: φ0.2 mm) manufactured by Nikkato Corporation M-3: Glass beads BZ-1 (size: φ0.99-1.40 mm) manufactured by AS ONE Corporation M-4: High-purity alumina balls AL9-1 (size: φ1 mm) manufactured by AS ONE Corporation

[0047] In the present invention, the ultrasonic treatment was also carried out as a method other than the ball mill treatment. The ultrasonic treatment was carried out by charging the components shown in Table 1 in a screw tube in a predetermined ratio, and treating for the time shown in Table 1.

[0048] <Homogeneity> The appearance of the prepared dispersion was visually inspected and evaluated according to the following criteria. The dispersion is preferably rated "A". A: No aggregated particles are visually observed in the solution, and a colloidal color is observed. C: Aggregated particles are visually observed, and no colloidal color is observed.

[0049] As shown in Table 1, in the dispersions of Examples 1 to 9 and 11, the metal species constituting the metal organic framework was Zr, and the dispersant contained an aliphatic amine compound which was a primary amine, secondary amine, or tertiary amine having one amino group in the molecule. Then, as shown in Table 2, compared to Comparative Example 1 which did not contain a dispersant, in Examples 1 to 9 and 11, the metal organic framework was dispersed in small sizes on the order of nanometers, and dispersions which showed excellent dispersion stability were obtained.

[0050] As shown in Table 1, in the dispersion of Comparative Example 2, the metal species constituting the metal organic framework was Zr, and the dispersant contained a quaternary aliphatic amine compound having one amino group in the molecule. As shown in Table 2, compared with Examples 1 to 9, the metal organic framework aggregated to large sizes on the order of μm, and the dispersion stability was poor.

[0051] As shown in Table 1, in the dispersions of Comparative Examples 3 to 5, the metal species constituting the metal organic framework was Zr, and the dispersant contained an aliphatic amine compound which was a primary amine, secondary amine, or tertiary amine having multiple amino groups in the molecule. As shown in Table 2, compared to Examples 1 to 9, the metal organic frameworks aggregated to large sizes on the order of μm, and the dispersion stability was poor.

[0052] As shown in Table 1, the dispersions of Comparative Examples 6 to 8 contain Zr as the metal species constituting the metal organic framework, and contain as the dispersant an aromatic amine compound that is a primary amine, secondary amine, or tertiary amine having one amino group in the molecule. As shown in Table 2, compared to Examples 1 to 9, the metal organic frameworks aggregated to large sizes on the order of μm, and the dispersion stability was poor.

[0053] As shown in Table 1, in the dispersions of Comparative Examples 9 to 12, the metal species constituting the metal organic framework was Zr, and the dispersant contained a monocarboxylic acid or a phosphonic acid. As shown in Table 2, compared with Examples 1 to 9, the metal organic frameworks aggregated to large sizes on the order of μm, and the dispersion stability was poor.

[0054] As shown in Table 1, the dispersions of Examples 10, 12, 13, and 15 contain Al as the metal species constituting the metal organic framework, and contain an aliphatic amine compound, which is a tertiary amine having one amino group in the molecule, as the dispersant. As shown in Table 2, compared to Comparative Example 13, in which the dispersant contains a monocarboxylic acid, Examples 10, 12, 13, and 15 contain dispersions in which the metal organic framework is dispersed in small sizes on the order of nanometers and exhibits excellent dispersion stability.

[0055] As shown in Table 1, the dispersion of Example 14 contains Zn as the metal species constituting the metal organic framework, and an aliphatic amine compound, which is a tertiary amine having one amino group in the molecule, as the dispersant. As shown in Table 2, a dispersion was obtained in which the metal organic framework was dispersed in small sizes on the order of nanometers and exhibited excellent dispersion stability.

[0056] As shown in Table 1, the dispersions of Example 1 and Examples 16 to 18 contain Zr as the metal species constituting the metal organic framework, and an aliphatic amine compound that is a tertiary amine having one nitrogen atom in the molecule as the dispersant. As shown in Table 2, although the media types and sizes differ in all cases, the metal organic frameworks are dispersed in small sizes on the order of nanometers, and dispersions that exhibit excellent dispersion stability were obtained.

[0057] As shown in Table 1, in the dispersion of Comparative Example 14, the metal species constituting the metal organic framework was Zr, and the dispersant contained an aliphatic amine compound that was a tertiary amine having one amino group in the molecule, but the treatment method was ultrasonic treatment, and compared to the dispersion of Example 1 in which mechanical pulverization treatment was performed using a ball mill, it was shown that the metal organic framework aggregated in large sizes on the order of μm and had poor dispersion stability.

[0058] As shown in Table 1, in the dispersions of Examples 19 and 20, the metal species constituting the metal organic framework was Zr, the dispersant contained an aliphatic amine compound that was a tertiary amine having one nitrogen atom in the molecule, and the dispersion medium was crosslinkable monomers D-1 and D-2. Then, as shown in Table 2, compared to Comparative Example 1 that did not contain a dispersant, in Examples 19 and 20, dispersions were obtained in which the metal organic framework was dispersed in small sizes on the order of nanometers and showed excellent dispersion stability.

[0059] As shown in Table 1, in the dispersion of Example 21, the metal species constituting the metal organic framework was Al, the dispersant contained an aliphatic amine compound that was a tertiary amine having one nitrogen atom in the molecule, and the solid content concentration was higher (15% by mass) than in Examples 1 to 20. Then, as shown in Table 2, a dispersion was obtained in which the metal organic framework was dispersed in small sizes on the order of nanometers and which exhibited excellent dispersion stability.

[0060] [Effect of Ball Mill Treatment on Crystal Structure] The dispersions obtained in Example 1 and Comparative Example 1 were diluted 10 times with toluene, and the precipitated white powder of the metal-organic framework was recovered on filter paper by Kiriyama filtration. After washing with DMF and MeOH, the obtained metal-organic framework powder was vacuum-dried at 150°C for 5 hours, to obtain a white powder.

[0061] To confirm the effect of ball milling on the crystal structure, the white powder obtained by the above treatment and the powder obtained in Production Example 1 before ball milling were analyzed for their crystal structures using XRD. As shown in FIG. 1 , the diffraction peak of the powder obtained from Comparative Example 1, which was ball milled without a dispersant, was different from the diffraction peaks of the powders obtained from Production Example 1 and Example 1, suggesting that the crystal structure was changed by the ball milling. These results suggest that in order to obtain a dispersion by mechanical milling while maintaining the crystal structure, it is important to include an aliphatic amine compound that is a primary amine, secondary amine, or tertiary amine having one amino group in the molecule as a dispersant.

[0062] To confirm the effect of ball milling on the crystal structure, the white powder obtained by the above treatment and the powder obtained in Production Example 1 before ball milling were analyzed by SEM-EDX. As shown in FIG. 2 , the elemental composition of the powder obtained in Comparative Example 1, which was ball milled without a dispersant, was different from the elemental compositions of the powders obtained in Production Example 1 and Example 1, suggesting that the crystal structure was changed by the ball milling. These results suggest that in order to obtain a dispersion by mechanical milling while maintaining the crystal structure, it is important to include an aliphatic amine compound that is a primary amine, secondary amine, or tertiary amine having one amino group in the molecule as a dispersant.

[0063] Similarly, the dispersions obtained in Examples 11 and 15 were diluted 10-fold with toluene, and the precipitated white metal-organic framework powder was recovered on filter paper by Kiriyama filtration. After washing with DMF and MeOH, the obtained metal-organic framework powder was vacuum-dried at 150°C for 5 hours to obtain a powder. The crystal structures of the obtained powder and the powders obtained in Production Examples 2 and 3 before ball milling were analyzed using XRD. As shown in Figure 3, it was suggested that the crystal structure was maintained before and after ball milling.

Claims

1. A method for producing a dispersion of metal-organic structures, (a) Components: A solid powder of a metal-organic structure comprising a metal ion and an organic ligand coordinated to the metal ion, wherein the metal ion is at least one selected from the group consisting of Zr ions, Al ions, and Zn ions, (b) Components: A dispersant comprising a primary amine, secondary amine, or tertiary amine having one amino group represented by the following formula (1) in its molecule, and (c1) an aliphatic amine compound soluble in the dispersion medium, 【Chemistry 1】 (In the formula, R １ and R ２ Each of these independently represents a hydrogen atom or an aliphatic hydrocarbon group, and * represents a bond with a carbon atom. A method for producing a metal-organic structure dispersion, comprising the steps of (1) mixing the component with a dispersion medium and (2) preparing a dispersion using the obtained mixture by a mechanical grinding method (provided that the mechanical grinding method ensures that (a) the crystalline structure of the metal-organic structure does not change and the crystalline structure of the solid powder is maintained).

2. The method for producing a metal-organic structure dispersion according to claim 1, wherein the metal-organic structure dispersion has a Z-average particle size of the solid powder of the metal-organic structure in the dispersion that is 10 nm or more and less than 1000 nm, and the settling velocity of the solid powder particles of the metal-organic structure in an environment with a centrifugal force of 470 G or less is 100 μm / s or less.

3. A method for producing a metal-organic structure composition, comprising the step (3) of mixing a metal-organic structure dispersion produced by the method of claim 1 or claim 2 with at least one of a dispersion medium (c2) component different from the dispersion medium (c1) component in the dispersion and an additive (d) component.

4. A method for producing a metal-organic structure dispersion according to claim 1 or claim 2, wherein the organic ligand is at least one selected from the group consisting of fumaric acid, terephthalic acid, isophthalic acid, 2-aminoterephthalic acid, 2-methylimidazole, and dicarboxypyrazole.

5. A method for producing a dispersion of a metal-organic structure according to claim 1 or claim 2, wherein the metal-organic structure is MIL-53, CAU-10, ZIF-8, MOF-801, MOF-303, UiO-66, or UiO-NH2-66.

6. The method for producing a metal-organic structure dispersion according to claim 1 or claim 2, wherein the mechanical grinding method is a grinding method using a ball mill or a bead mill.

7. The method for producing a metal-organic structure dispersion according to claim 6, wherein the ball mill or bead mill has a ball diameter or bead diameter of 0.01 mm or more and 10 mm or less, and the material of the ball or bead is at least one selected from the group consisting of metal and glass.

8. (a) Components: A solid powder of a metal-organic structure comprising a metal ion and an organic ligand coordinated to the metal ion, wherein the metal ion is at least one selected from the group consisting of Al ions and Zn ions, (b) Components: A dispersant comprising a primary amine, secondary amine, or tertiary amine having one amino group represented by the following formula (1) in its molecule, and (c1) an aliphatic amine compound soluble in the dispersion medium, 【Chemistry 2】 (In the formula, R １ and R ２ Each of these independently represents a hydrogen atom or an aliphatic hydrocarbon group, and * represents a bond with a carbon atom. (c1) Component: A dispersion containing a dispersion medium, A dispersion of a metal-organic structure in which the Z-average particle size of the solid powder of the metal-organic structure in the dispersion is 10 nm or more and less than 1000 nm, and the sedimentation velocity of the solid powder particles of the metal-organic structure in an environment with a centrifugal force of 470 G or less is 100 μm / s or less.

9. The metal-organic structure dispersion according to claim 8, wherein the organic ligand is at least one selected from the group consisting of fumaric acid, terephthalic acid, isophthalic acid, 2-aminoterephthalic acid, 2-methylimidazole, and dicarboxypyrazole.

10. The metal-organic structure dispersion according to claim 8 or claim 9, wherein the metal-organic structure is MIL-53, CAU-10, ZIF-8, or MOF-303.

11. A metal-organic structure dispersion according to claim 8 or claim 9, and comprising at least one of a dispersion medium (c2) component and an additive (d) component different from the dispersion medium (c1) component in the dispersion. Metal-organic framework composition.

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