Method for producing metal fluorides

Abstract

This invention provides a manufacturing method that enables the industrial mass production of metal fluorides through mechanochemical processing. [Solution] A method for producing a metal fluoride, comprising the step of mechanochemically treating 10 g or more of a fluorine-containing compound with at least one metal oxide selected from the group consisting of alkali metal oxides and alkaline earth metal oxides to obtain a metal fluoride.

Description

[Technical Field]

[0001] This disclosure relates to a method for producing metal fluorides. [Background technology]

[0002] A method for defluorinating polyfluorinated ethylene is known, which involves mechanochemical treatment using a planetary ball mill in the presence of calcium oxide (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2000-70401 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, the method using planetary mills has the problem of being difficult to mass-produce industrially.

[0005] This disclosure aims to provide a manufacturing method that enables the industrial mass production of metal fluorides by mechanochemical treatment. [Means for solving the problem]

[0006] (1) of this disclosure is a method for producing a metal fluoride, comprising the step of obtaining a metal fluoride by mechanochemical treatment of 10 g or more of a fluorine-containing compound and at least one metal oxide selected from the group consisting of alkali metal oxides and alkaline earth metal oxides.

[0007] Disclosure (2) is a manufacturing method according to Disclosure (1) in which the mechanochemical treatment is performed by applying an energy of 1.5 J / s / g or more.

[0008] The present disclosure (3) is a production method according to the present disclosure (1) or (2), which performs the mechanochemical treatment by adding energy of 1.8 to 10.0 J / s / g.

[0009] The present disclosure (4) is a production method of any combination with any one of the present disclosures (1) to (3), in which the mechanochemically treated product obtained by the mechanochemical treatment substantially does not contain organic fluorine.

[0010] The present disclosure (5) is a production method of any combination with any one of the present disclosures (1) to (4), which performs the mechanochemical treatment without using a planetary mill.

[0011] The present disclosure (6) is a production method of any combination with any one of the present disclosures (1) to (5), which performs the mechanochemical treatment using a vibration mill.

[0012] The present disclosure (7) is a production method of any combination with any one of the present disclosures (1) to (6), which performs the mechanochemical treatment using a grinding medium with a length of at least 15 mm in at least one dimension.

[0013] The present disclosure (8) is a production method of any combination with any one of the present disclosures (1) to (7), which performs the mechanochemical treatment using a grinding medium with three-dimensional lengths of 30 to 40 mm.

[0014] The present disclosure (9) is a production method of any combination with any one of the present disclosures (1) to (8), which performs the mechanochemical treatment in the presence of a grinding aid having an old Mohs hardness of 5 to 8.5.

[0015] The present disclosure (10) is a production method according to the present disclosure (9), in which the grinding aid is titanium oxide.

[0016] The present disclosure (11) is a production method according to the present disclosure (9) or (10), in which the grinding aid is particles having an average particle diameter of 5 to 10 μm.

[0017] The present disclosure (12) is a production method of any combination with any one of the present disclosures (9) to (11) in which the usage amount of the pulverization aid is 0.5 to 3 equivalents with respect to 1 equivalent of the fluorine-containing compound.

[0018] The present disclosure (13) is a production method of any combination with any one of the present disclosures (1) to (12) in which the metal oxide is calcium oxide.

[0019] The present disclosure (14) is a production method of any combination with any one of the present disclosures (1) to (13) in which the usage amount of the metal oxide is 1 to 10 equivalents with respect to 1 equivalent of the fluorine-containing compound.

[0020] The present disclosure (15) is a production method of any combination with any one of the present disclosures (1) to (14) in which the fluorine-containing compound is a fluorine-containing low molecular weight compound having a molecular weight of 2000 or less.

[0021] The present disclosure (16) is a production method of any combination with any one of the present disclosures (1) to (14) in which the fluorine-containing compound is a fluorine-containing polymer.

[0022] The present disclosure (17) is a production method of any combination with any one of the present disclosures (1) to (14) in which the fluorine-containing compound is at least one selected from the group consisting of polytetrafluoroethylene, polydifluoroethylene, and fluorine-based telomers.

Advantages of the Invention

[0023] According to the present disclosure, it is possible to provide a production method capable of industrially mass-producing metal fluoride by mechanochemical treatment.

Modes for Carrying Out the Invention

[0024] Hereinafter, the present disclosure will be specifically described.

[0025] This disclosure relates to a method for producing a metal fluoride, comprising the step of obtaining a metal fluoride by mechanochemical treatment of 10 g or more of a fluorine-containing compound and at least one metal oxide selected from the group consisting of alkali metal oxides and alkaline earth metal oxides.

[0026] In the manufacturing method disclosed herein, 10 g or more of a fluorine-containing compound is subjected to mechanochemical treatment, thereby enabling the industrial mass production of metal fluorides by mechanochemical treatment. The amount of the fluorine-containing compound treated is preferably 12 g or more, more preferably 13 g or more, and even more preferably 14 g or more. The upper limit of the processing volume can be determined according to the scale of production, but it may be, for example, 1 kg or 10 kg. The processing volume mentioned above represents the processing volume in a single reaction vessel. Furthermore, it represents the processing volume per 0.1 hours for continuous processing, and the processing volume per batch for batch processing. It is difficult to mechanochemically treat fluorine-containing compounds in the above-mentioned range using a planetary mill.

[0027] The fluorine-containing compound used in the manufacturing method of this disclosure may be any compound having a fluorine atom, but inorganic fluorine compounds other than calcium fluoride are not included. The above fluorine-containing compound may be a compound having a fluorine atom bonded to a carbon atom, and is preferably an organic compound having a fluorine atom bonded to a carbon atom. Furthermore, the fluorine-containing compound is preferably solid at 25°C, as this facilitates mechanochemical treatment.

[0028] The above-mentioned fluorine-containing compound is preferably a fluorine-containing polymer compound, and more preferably a fluorine-containing polymer. The molecular weight of the fluorine-containing polymer compound is usually greater than 2000 and can be measured by known methods depending on the type of compound.

[0029] The above-mentioned fluorine-containing polymer preferably contains polymerization units based on at least one monomer selected from the group consisting of tetrafluoroethylene [TFE], difluoroethylene, chlorotrifluoroethylene [CTFE], hexafluoropropylene [HFP], perfluoro(alkyl vinyl ether) [PAVE], trifluoroethylene, and monofluoroethylene. Examples of the above-mentioned difluoroethylenes include vinylidene fluoride [VdF] and 1,2-difluoroethylene. The above fluorine-containing polymer more preferably contains polymerization units based on at least one monomer selected from the group consisting of TFE, difluoroethylene, and CTFE; even more preferably contains polymerization units based on at least one monomer selected from the group consisting of TFE, VdF, and CTFE; even more preferably contains polymerization units based on at least one monomer selected from the group consisting of TFE and VdF; and particularly preferably contains polymerization units based on VdF. The above fluorine-containing polymer may also contain polymerization units based on TFE.

[0030] The above-mentioned fluorine-containing polymer may be a fluororesin or a fluororubber.

[0031] The above fluororesins include polytetrafluoroethylene [PTFE], tetrafluoroethylene [TFE] / perfluoro(alkyl vinyl ether) [PAVE] copolymer [PFA], TFE / hexafluoropropylene [HFP] copolymer [FEP], ethylene [Et] / TFE copolymer [ETFE], Et / TFE / HFP copolymer [EFEP], polychlorotrifluoroethylene [PCTFE], chlorotrifluoroethylene [CTFE] / TFE copolymer, CTFE / TFE / PAVE copolymer, Et / CTFE copolymer, polyfluoroethylene Examples include vinyl oxide [PVF], polydifluoroethylene (polyvinylidene fluoride [PVdF], poly(1,2-difluoroethylene) etc.), vinylidene fluoride [VdF] / TFE copolymer, VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / HFP / (meth)acrylic acid copolymer, VdF / CTFE copolymer, VdF / pentafluoropropylene copolymer, VdF / PAVE / TFE copolymer, TFE / perfluoroalkyl allyl ether copolymer, etc., which can be used individually or in combination. The above perfluoroalkyl allyl ether is CF2=CFCF2-O-Rf 1 (Rf 1 It is a monomer represented by a perfluoroalkyl group having 1 to 5 carbon atoms.

[0032] The above-mentioned fluororesin may be a fluororesin having monomer units having CH bonds, and may be a perhalopolymer, preferably a perfluoropolymer, in which halogen atoms are bonded to all carbon atoms constituting the main chain of the polymer.

[0033] Examples of the above-mentioned fluororubbers include vinylidene fluoride [VdF]-based fluororubbers, tetrafluoroethylene [TFE] / propylene [Pr]-based fluororubbers, TFE / Pr / VdF-based fluororubbers, ethylene [Et] / hexafluoropropylene [HFP]-based fluororubbers, Et / HFP / VdF-based fluororubbers, Et / HFP / TFE-based fluororubbers, fluorosilicone-based fluororubbers, and fluorophosphazene-based fluororubbers, which can be used individually or in combination.

[0034] Examples of the above-mentioned VdF-based fluororubbers include VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / chlorotrifluoroethylene [CTFE] copolymer, VdF / CTFE / TFE copolymer, VdF / perfluoro(alkyl vinyl ether) [PAVE] copolymer, VdF / TFE / PAVE copolymer, VdF / HFP / PAVE copolymer, VdF / HFP / TFE / PAVE copolymer, VdF / TFE / Pr copolymer, VdF / Et / HFP copolymer, and VdF / polymer of a fluorine-containing monomer represented by the following formula (1). Formula (1): CH2=CFRf 2 (1) (In the formula, Rf 2 (These are linear or branched fluoroalkyl groups having 1 to 12 carbon atoms.)

[0035] As the fluorine-containing polymer, fluororesins are preferred, at least one selected from the group consisting of PTFE, polydifluoroethylene, and ETFE is more preferred, at least one selected from the group consisting of PTFE and polydifluoroethylene is even more preferred, at least one selected from the group consisting of PTFE and PVdF is even more preferred, and PTFE is particularly preferred. As the above-mentioned fluorine-containing polymer, from the viewpoint of reactivity, fluororesins having monomer units with CH bonds are also preferred, at least one selected from the group consisting of polydifluoroethylene and ETFE is more preferred, at least one selected from the group consisting of PVdF and ETFE is even more preferred, and PVdF is even more preferred.

[0036] The above-mentioned fluorine-containing compound does not have to be a polymer, as long as it is solid at 25°C; it may also be a fluorine-containing low-molecular-weight compound. The above-mentioned fluorine-containing low-molecular-weight compound may have a molecular weight of 2000 or less. The molecular weight of the above-mentioned fluorine-containing low-molecular-weight compound can be determined by calculation from its chemical formula.

[0037] The above fluorine-containing low molecular weight compound is preferably a fluorine-based telomer. Examples of the above fluorine-based telomer include the following formula: C2F5(CF2CF2) n -X (In the formula, X represents a halogen atom, and n represents an integer of 5 or more.) Examples of the compound represented thereby include those. In the above formula, X may be a halogen atom other than a fluorine atom, preferably a chlorine atom, a bromine atom or an iodine atom, more preferably a bromine atom or an iodine atom, and still more preferably an iodine atom. In the above formula, n is an integer of 5 or more, and preferably an integer of 10 or less.

[0038] The above fluorine-containing low molecular weight compound is represented by the following general formula (I): Y-(CF2) x1 -(CH2) y1 -A (I) (In the formula, Y represents H or F. x1 represents an integer of 4 or more, and y1 represents an integer of 0 to 3. A represents -SO3M I or -COOM I , M I [[ID=2:8]]represents H, NH4, Li, Na, Mg, Al, K or Ca.) Compound (I) represented by the formula, and the following general formula (II): F-(CF2) x2 O(CFXCF2O) y2 -CFX-A (II) (In the formula, x2 represents an integer of 1 or more, and y2 represents an integer of 0 to 10. X represents F or CF3. A represents -SO3M II or -COOM II , M II represents H, NH4, Li, Na, Mg, Al, K or Ca.) It is also preferable that it is at least one fluorine-containing organic acid compound selected from the group consisting of compound (II) represented by the formula.

[0039] Examples of the above compound (I) include fluorocarboxylic acids and their salts, such as perfluorocarboxylic acids and their salts. Examples of the salts include ammonium salts and sodium salts. Furthermore, compound (I) may also include fluorosulfonic acid and its salts, such as perfluorosulfonic acid and its salts. Examples of salts include ammonium salts and sodium salts. Examples of the above compound (II) include perfluoroether carboxylic acids and their salts, such as 2,3,3,3-tetrafluoro-2-[1,1,2,3,3,3-hexafluoro-2-(trifluoromethoxy)propoxy]-propanoic acid.

[0040] The above-mentioned fluorine-containing low-molecular-weight compound may be adsorbed onto an adsorbent. In this embodiment, the solid obtained by adsorbing the above-mentioned fluorine-containing low-molecular-weight compound onto an adsorbent may be subjected to mechanochemical treatment. The above-mentioned adsorbent is not limited to any solid capable of adsorbing the above-mentioned fluorine-containing low-molecular-weight compound, but it is preferably at least one selected from the group consisting of activated carbon, silica gel, clay, metal-organic framework (MOF), and zeolite.

[0041] The above-mentioned fluorine-containing compound may be calcium fluoride. In this case, a metal fluoride different from calcium fluoride can be obtained by the above-mentioned mechanochemical treatment.

[0042] In the manufacturing method of this disclosure, a composition containing the above-mentioned fluorine-containing compound and other components may be subjected to mechanochemical treatment. The other components mentioned above can be used to the extent that they do not impair the effectiveness of the manufacturing method of this disclosure. Examples of the other components include general fillers and polymers, and the adsorbents mentioned above.

[0043] Examples of common fillers mentioned above include inorganic fillers such as glass fibers, glass beads, carbon fibers, spherical carbon, carbon black, graphite, silica, alumina, mica, silicon carbide, boron nitride, aluminum nitride, titanium oxide, bismuth oxide, cobalt oxide, magnesium oxide, molybdenum disulfide, bronze, gold, silver, copper, nickel, aluminum fluoride, carbon fluoride, and carbon black.

[0044] The above-mentioned common polymers include polyolefin resins such as polyethylene and polypropylene; polyamide [PA] resins such as nylon 6, nylon 11, nylon 12, nylon 46, nylon 66, nylon 610, nylon 612, and nylon MXD6; polyesters such as polyethylene terephthalate [PET], polybutylene terephthalate [PBT], polyarylate, aromatic polyesters (including liquid crystal polyesters), and polycarbonate [PC]; polyacetal [POM] resins; polyether resins such as polyphenylene oxide [PPO], modified polyphenylene ether, and polyetheretherketone [PEEK]; polyamideimide [PAI] resins such as polyaminobismaleimide; polysulfone resins such as polysulfone [PSF] and polyethersulfone [PES]; vinyl polymers such as ABS resin and poly-4-methylpentene-1 (TPX resin), as well as polyphenylene sulfide [PPS], polyketone sulfide, polyetherimide, polyimide [PI], and epoxy resins. The above nylon MXD6 is a crystalline polycondensate obtained from metaxylenediamine [MXD] and adipic acid. The general polymers mentioned above may be non-fluorinated polymers.

[0045] The content of the above-mentioned other components may be 50% by mass or less, preferably 30% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and may be 0% by mass or more, 0.01% by mass or more, 0.1% by mass or more, or 1% by mass or more.

[0046] The above-mentioned fluorine-containing compound (or the above-mentioned composition if other components are present; the same applies hereinafter) may be in powder form, molded form, or waste material from the product manufacturing process or after use. It may also be heated above its melting point. If necessary, the above-mentioned fluorine-containing compound may be pulverized before use.

[0047] The shape of the fluorine-containing compound is not particularly limited and may be in the form of powder, sheet, block, pellet, flake, etc., but from the viewpoint of reaction efficiency, it is preferably in the form of sheet, block, pellet or flake, more preferably in the form of sheet, block or pellet, even more preferably in the form of sheet or block, and even more preferably in the form of block.

[0048] The size of the fluorine-containing compound mentioned above is not particularly limited, but it was found that the reaction efficiency improved to some extent with larger compounds. Generally, smaller compounds tend to have higher reaction efficiency, so this finding is unexpected. Of the three dimensions representing the size of the fluorine-containing compound described above, the length of at least one dimension may be 0.001 mm or more, preferably 0.010 mm or more, more preferably 0.100 mm or more, even more preferably 1.0 mm or more, even more preferably 2.0 mm or more, particularly preferably 3.0 mm or more, and also preferably 20 mm or less, more preferably 10 mm or less, even more preferably 5.0 mm or less, and even more preferably 4.0 mm or less. It is preferable that the length of the shortest dimension among the three dimensions representing the size of the fluorine-containing compound is within the above range. Furthermore, it is more preferable that at least two of the three dimensions representing the size of the fluorine-containing compound are within the above range, and even more preferable that the three-dimensional length is within the above range. The dimensional length indicating the size of the above-mentioned fluorine-containing compound is measured using a micrometer or caliper.

[0049] When the above-mentioned fluorine-containing compound is in powder form, the average particle diameter can also be used as an indicator of size. When the above-mentioned fluorine-containing compound is in powder form, the average particle diameter may be 10 μm or more, preferably 30 μm or more, more preferably 100 μm or more, even more preferably 200 μm or more, and preferably 4000 μm or less, more preferably 2000 μm or less, and even more preferably 1000 μm or less. The average particle size of the above-mentioned fluorine-containing compound was measured using a laser diffraction / scattering particle size distribution analyzer manufactured by Nikkiso Co., Ltd., in a dry manner at a vacuum pressure of 20 mH2O, and was defined as being equal to the particle size corresponding to 50% of the integrated particle size distribution (volume basis).

[0050] The metal oxide used in the manufacturing method of this disclosure is at least one selected from the group consisting of alkali metal oxides and alkaline earth metal oxides. Examples of the alkali metal oxides mentioned above include lithium oxide, sodium oxide, potassium oxide, etc., and one or more of these can be used. Examples of the above-mentioned alkaline earth metal oxides include calcium oxide, strontium oxide, and barium oxide, and one or more of these can be used. From the viewpoint of reactivity, alkaline earth metal oxides are preferred among the above metal oxides, at least one selected from the group consisting of calcium oxide and strontium oxide is more preferred, and calcium oxide (CaO) is even more preferred.

[0051] The amount of the metal oxide used in the above mechanochemical treatment is preferably 0.01 equivalents or more, more preferably 0.05 equivalents or more, even more preferably 0.1 equivalents or more, even more preferably 0.5 equivalents or more, particularly preferably 1 equivalent or more, and also preferably 10 equivalents or less, more preferably 8 equivalents or less, even more preferably 5 equivalents or less, and even more preferably 3 equivalents or less. If the above-mentioned fluorine-containing compound is a fluorine-containing polymer, the equivalent amount shall be calculated based on the monomers constituting the fluorine-containing polymer.

[0052] The above-described mechanochemical treatment is a treatment method that activates reactants (preferably solid reactants) by applying mechanical energy through methods such as shearing, compression, stretching, grinding, friction, kneading, mixing, dispersion, crushing, and shaking, thereby imparting structural changes, phase transitions, reactivity, adsorption properties, catalytic activity, etc. The method of mechanochemical treatment is not particularly limited, but examples include compression shear treatment, impact treatment, and mixed shear friction treatment, with the impact treatment method being preferred.

[0053] The energy in the above-mentioned mechanochemical treatment is energy that is mechanically applied, and is a mechanical phenomenon that changes the position or deforms an object through the action of force, and includes potential energy, kinetic energy, etc. Among mechanical energies, energy that does work is called impact energy, shear energy, vibration energy, etc. From the viewpoint of being able to apply high energy to the workpiece, impact energy applied by vibratory mills, attritor mills, jet mills, etc., is preferred, but any energy that is applied to the reactant is acceptable and is not limited to impact energy.

[0054] The above mechanochemical treatment is usually carried out using a grinding medium. Preferably, the grinding medium is not connected to the reaction vessel. The grinding medium may be used in combination with components connected to the reaction vessel, such as a stirring member.

[0055] The shape of the pulverized medium is not particularly limited and may be spherical, ellipsoidal, cylindrical, cylindrical, bale-shaped, tea caddy-shaped, etc. However, from the viewpoint of reaction efficiency, it is preferably spherical, ellipsoidal, or cylindrical, more preferably spherical or ellipsoidal, and even more preferably spherical.

[0056] In terms of reaction efficiency, the above-mentioned grinding medium may have a length of at least one dimension of the three dimensions representing the size of the grinding medium of 5 mm or more, preferably 10 mm or more, more preferably 15 mm or more, even more preferably 20 mm or more, even more preferably 25 mm or more, particularly preferably 30 mm or more, and also preferably 100 mm or less, more preferably 70 mm or less, even more preferably 50 mm or less, and even more preferably 40 mm or less. It is preferable that the length of the shortest dimension among the three dimensions representing the size of the pulverized medium is within the above range. Furthermore, it is more preferable that at least two of the three dimensions representing the size of the pulverized medium are within the above range, and even more preferable that the three-dimensional length is within the above range. If the above-mentioned crushed medium is spherical, it is preferable that its diameter is within the above-mentioned range. By using a pulverized medium of the size described above, the energy required for mechanochemical processing can be further increased, thereby improving reaction efficiency. As a result, mechanochemical processing can be easily performed using equipment that is readily industrializable.

[0057] The material of the grinding medium is not particularly limited, and examples include steels such as carbon steel, stainless steel, and chromium steel, as well as zirconia, tungsten carbide, agate, silicon nitride, alumina, and polyamide. One or more of these materials can be used. Among these, steels and zirconia are preferred, steels are more preferred, and carbon steel and stainless steel are even more preferred.

[0058] From the viewpoint of reaction efficiency, the amount of the above-mentioned grinding medium used is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 83% by mass or less, relative to the above-mentioned fluorine-containing compound.

[0059] The material of the reaction vessel used in the above mechanochemical treatment is not particularly limited, and examples include carbon steel, stainless steel, chromium steel, and other types of steel, as well as zirconia, tungsten carbide, agate, silicon nitride, alumina, polyamide, etc., and one or more of these can be used. Among these, steels and zirconia are preferred, steels are more preferred, and carbon steel and stainless steel are even more preferred. The material of the reaction vessel may be the same as or different from that of the grinding medium described above.

[0060] From the viewpoint of reaction efficiency, the packing ratio of the pulverized medium to the internal volume of the reaction vessel is preferably 0.05 volume% or more, preferably 0.1 volume% or more, more preferably 0.3 volume% or more, even more preferably 1.0 volume% or more, and also preferably 20 volume% or less, more preferably 10 volume% or less, and even more preferably 6.0 volume% or less.

[0061] The above mechanochemical treatment may be carried out by adding an energy of 1.5 J / s / g or more. From the viewpoint of reaction efficiency, the above energy is preferably 1.8 J / s / g or more, more preferably 2.0 J / s / g or more, even more preferably 2.5 J / s / g or more, preferably 30.0 J / s / g or less, more preferably 15.0 J / s / g or less, even more preferably 10.0 J / s / g or less, and even more preferably 5.0 J / s / g or less. By adding energy within the above range, the reaction efficiency can be further increased, making it easier to perform mechanochemical processing using equipment that is easily industrialized. The energy to be added is not particularly limited, but collision energy is especially preferred.

[0062] The above energy, for example in the case of collision energy, is the collision energy per unit mass and is calculated using the following formula with simulation software based on the method described in AIChE Journal, Vol.52, No.10, 2006, pp.3421-3426. The simulation software is not limited to those that can perform calculations based on the above method; for example, KIK DEM manufactured by Tohoku University or UX-DEM manufactured by JX Metals can be used.

number

[0063] In the above mechanochemical treatment, the ratio of the substance to be treated to the internal volume of the reaction vessel is preferably 0.1 g / L or more, more preferably 1.0 g / L or more, even more preferably 10.0 g / L or more, preferably 150.0 g / L or less, more preferably 100.0 g / L or less, even more preferably 50.0 g / L or less, even more preferably 30.0 g / L or less, and particularly preferably 25.0 g / L or less, from the viewpoint of reaction efficiency. The proportion of the treated material mentioned above is the total proportion of all raw materials that undergo mechanochemical treatment, including the fluorine-containing compound, the metal oxide, and the grinding aids described later.

[0064] The above mechanochemical treatment is preferably carried out in the presence of a grinding aid with a prior Mohs hardness of 5 to 8.5. By using a grinding aid with a prior Mohs hardness within this range, high energy can be applied to the material being treated, further improving the reaction efficiency. In addition, since the grinding aid is not too hard, wear on the grinding medium and reaction vessel can be suppressed. The above-mentioned Mohs hardness is preferably 5.5 or higher, preferably 8 or lower, and more preferably 7.5 or lower. The above-mentioned old Mohs hardness is measured using a Mohs hardness tester.

[0065] Examples of the above-mentioned grinding aids include titanium dioxide (TiO2), quartz (SiO2), zirconia (ZrO2), magnesium oxide (MgO), etc., and one or more of these can be used. Among these, at least one selected from the group consisting of titanium dioxide and quartz is preferred, and titanium dioxide is more preferred. Note that due to differences in crystal structure and other factors, even grinding aids of the same type (name) may have different prior Mohs hardness values. The grinding aids exemplified above are those whose prior Mohs hardness falls within the range described above and whose type is as described above.

[0066] The above-mentioned grinding aid is preferably in the form of particles. The average particle size of the above-mentioned grinding aid is preferably 1 μm or more, more preferably 5 μm or more, preferably 5 mm or less, more preferably 1 mm or less, even more preferably 500 μm or less, even more preferably 100 μm or less, even more preferably 50 μm or less, even more preferably 30 μm or less, and particularly preferably 10 μm or less. The average particle size of the above-mentioned grinding aid is measured using a laser diffraction / scattering particle size distribution analyzer manufactured by Nikkiso Co., Ltd.

[0067] The amount of the above-mentioned grinding aid used is preferably 0.01 equivalents or more, more preferably 0.05 equivalents or more, even more preferably 0.1 equivalents or more, even more preferably 0.3 equivalents or more, particularly preferably 0.5 equivalents or more, and also preferably 5 equivalents or less, more preferably 3 equivalents or less, even more preferably 1 equivalent or less, and even more preferably 0.8 equivalents or less.

[0068] In the above mechanochemical treatment, it is also preferable to set the size of the fluorine-containing compound to 0.002 to 0.15 times the volume of the grinding medium used in the mechanochemical treatment. By using a fluorine-containing compound that is somewhat large in this way, the reaction efficiency can be further improved. The size of the above-mentioned fluorine-containing compound is preferably 0.005 times or more the size of the above-mentioned grinding medium, more preferably 0.010 times or more, more preferably 0.040 times or more, more preferably 0.050 times or more, particularly preferably 0.060 times or more, and also preferably 0.12 times or less, more preferably 0.10 times or less, and even more preferably 0.08 times or less.

[0069] The above mechanochemical treatment may also be carried out using two or more grinding media of different sizes. This allows high energy to be applied to the material being treated, further improving the reaction efficiency. Preferably, the two or more grinding media of different sizes have different volumes. Furthermore, preferably, the two or more grinding media of different sizes have different lengths in at least one dimension of the three dimensions that represent the size of the grinding media, more preferably, they have different lengths in at least two dimensions, and even more preferably, they have different lengths in three dimensions.

[0070] It is preferable to use at least a first grinding medium and a second grinding medium smaller than the first grinding medium as the two or more grinding media of different sizes mentioned above. The second grinding medium preferably has a smaller volume than the first grinding medium. The second grinding medium also preferably has a shorter length in at least one dimension of the three dimensions representing the size of the grinding medium than the first grinding medium, more preferably has a shorter length in at least two dimensions than the first grinding medium, and even more preferably has a shorter length in three dimensions than the first grinding medium.

[0071] The first grinding medium can be the same as those described above as grinding media typically used in mechanochemical treatment. The amount of the first grinding medium used can be within the same range as the amount of grinding media typically used in mechanochemical treatment.

[0072] The size of the second grinding medium is preferably 0.01 times or more, more preferably 0.05 times or more, even more preferably 0.1 times or more, and preferably less than 1.0 times, more preferably 0.5 times or less, and even more preferably 0.3 times or less, based on volume.

[0073] The second grinding medium preferably has a length of at least one dimension of the three dimensions representing the size of the grinding medium of more than 1 mm, more preferably 1.5 mm or more, even more preferably 2 mm or more, even more preferably 2.5 mm or more, and also preferably less than 30 mm, more preferably less than 25 mm, even more preferably less than 20 mm, even more preferably less than 15 mm, particularly preferably less than 10 mm, and may also be less than 5 mm. It is preferable that the length of the shortest dimension among the three dimensions representing the size of the second grinding medium is within the above range. Furthermore, it is more preferable that at least two of the three dimensions representing the size of the pulverized medium are within the above range, and even more preferable that the three-dimensional length is within the above range. If the second grinding medium is spherical, it is preferable that its diameter is within the above range. By using a grinding medium of the size described above as the second grinding medium, the reaction efficiency can be further increased. Furthermore, having a certain size allows the second grinding medium to be easily separated from the product after the reaction using a sieve or similar method.

[0074] The shape and material of the second grinding medium are the same as those described above for the grinding medium (first grinding medium) that is normally used in the above-mentioned mechanochemical treatment, and the preferred form is also the same. The first grinding medium and the second grinding medium may have the same shape and material, or they may be different.

[0075] From the viewpoint of reaction efficiency, the amount of the second grinding medium used is preferably 20% by volume or more, more preferably 30% by volume or more, even more preferably 40% by volume or more, and preferably 70% by volume or less, more preferably 60% by volume or less, and even more preferably 50% by volume or less.

[0076] The apparatus for mechanochemical processing is not particularly limited as long as it can apply mechanical energy in the manner described above, and known pulverizers and mixers can be used. For example, pulverizers such as ball mills, rod mills, jet mills, rotary mills, vibratory mills, and SAG mills; grinders such as rotary stone mills and mortars; (horizontal axis rotation) container rotary mixing devices such as horizontal cylindrical, V-type, double cone, cuboid, S-type, and continuous V-type; (baffle plate) container rotary mixing devices such as horizontal cylindrical, V-type, double cone, and ball mill types; (rotational vibration) container rotary mixing devices such as rocking and cross rotary types; (water) Examples include: flat-axis rotating fixed-container mixing devices; ribbon type, screw type, planetary type, turbine type, high-speed fluid type, rotating disc type and Mahler type (vertical axis rotating) fixed-container mixing devices; vibrating mill type and sieve type (vibrating) fixed-container mixing devices; non-uniform fluidized bed, swirling fluidized bed, riser tube type and jet pump type (fluidizing) fluid motion mixing devices; gravity type and static mixer (gravity) fluid motion mixing devices; twin-shaft kneaders, single-shaft kneaders, mixers, roll mills, etc.

[0077] As the apparatus for performing the above-mentioned mechanochemical treatment, a rotary mill and a vibratory mill are preferred, with a vibratory mill being more preferred.

[0078] The above mechanochemical treatment is preferably carried out without using a planetary mill. While planetary mills are devices that can supply high energy, they also generate a large amount of wear particles (see, for example, J.Soc. Powder Technol., Japan, 44, 186-190 (2007) [https: / / www.jstage.jst.go.jp / article / sptj1978 / 44 / 3 / 44_3_186 / _pdf / -char / ja]). The inclusion of wear particles can interfere with the use of the product after the reaction. The manufacturing method disclosed herein allows for the reaction of fluorine-containing compounds under conditions that minimize the generation of wear particles from the device. Furthermore, methods using general-purpose devices such as ball mills and vibratory mills, rather than planetary mills, have the advantage of being easily industrialized.

[0079] The temperature for the above mechanochemical treatment is preferably 5°C or higher, more preferably 10°C or higher, even more preferably 15°C or higher, even more preferably 20°C or higher, and also preferably 300°C or lower, more preferably 250°C or lower, even more preferably 200°C or lower, and even more preferably 160°C or lower.

[0080] In particular, if the fluorine-containing compound is a fluorine-containing polymer compound that does not contain hydrogen, the reaction is accelerated by heating, so it is preferable to carry out the reaction at room temperature (25°C) or higher.

[0081] The duration of the above mechanochemical treatment can be determined according to the equipment used, the amount of material to be treated, etc., but for example it may be 0.1 hours or more, 0.5 hours or more, 1 hour or more, or 100 hours or less, 50 hours or less, or 30 hours or less.

[0082] The above mechanochemical treatment can be carried out in any atmosphere, such as in air, inert gas, or in a vacuum. From the viewpoint of low cost, it is preferable to carry it out in air.

[0083] The above mechanochemical treatment is preferably carried out in a dry manner. Carrying it out in a dry manner means that the amount of liquid in the reaction system is 5% by mass or less, preferably 1% by mass or less, more preferably 0.1% by mass or less, and even more preferably 0.01% by mass or less.

[0084] The above mechanochemical treatment allows the fluorine-containing compound to be reacted. The reaction may be one that generates fluoride ions, and is preferably a defluorination reaction.

[0085] The above mechanochemical treatment yields a metal fluoride. The metal fluoride may be at least one selected from the group consisting of alkali metal fluorides and alkaline earth metal fluorides, preferably an alkaline earth metal fluoride, more preferably at least one selected from the group consisting of potassium fluoride and calcium fluoride (CaF2), with calcium fluoride (CaF2) being the most preferred.

[0086] The manufacturing method disclosed herein can be used not only for the production of metal fluorides but also for the decomposition (defluorination) of fluorine-containing compounds. The manufacturing method of this disclosure also allows for obtaining metal fluorides from organofluorine compounds by using organofluorine compounds as fluorine-containing compounds. The reaction rate of the organofluorine compound is preferably 30% or more, more preferably 50% or more, even more preferably 90% or more, most preferably 99% or more, and may be 100% or less. The reaction rate of the above-mentioned organofluorine compounds can be determined using the following formula, based on the amount of organofluorine (by mass) in the mechanochemically treated product described later. Reaction rate of organofluorine compounds = ((Amount of fluorine in organofluorine compounds before mechanochemical treatment - Amount of organofluorine in mechanochemically treated product) / Amount of fluorine in organofluorine compounds before mechanochemical treatment) × 100 The amount of fluorine in the organofluorine compound before the above mechanochemical treatment can be measured by ion chromatography.

[0087] It is preferable that the mechanochemically treated product (product containing metal fluoride) manufactured is substantially free of organofluorine. The statement that a mechanochemically treated product is substantially free of organic fluorine means that the amount of organic fluorine in the mechanochemically treated product is 1000 ppm by mass or less. The amount of organic fluorine in the above-mentioned mechanochemically treated product may be 500 ppm by mass or less, preferably 100 ppm by mass or less, and may be 0 ppm by mass or more, or may be an amount below the detection limit. The amount of organic fluorine in mechanochemically treated materials can be measured by the following method. A 0.5 g sample of mechanochemically treated material is extracted with 10 mL of methanol for 2 hours at 60°C using sonication to extract the organofluorine compounds from the sample and obtain an extract. The methanol in the obtained extract is concentrated and analyzed by combustion ion chromatography, and the mass of fluoride ions derived from the detected organofluorine compounds in the extract is measured. Using the mass of fluoride ions measured above, the amount of organofluorine is calculated using the following formula. The amount of organic fluorine in mechanochemically treated material (mass ppm) = ((mass of detected fluoride ions) / 0.5 g) × 10 6 The amount of organic fluorine in mechanochemically treated material (molar ppm) = ((mass of detected fluoride ions) / 0.5 g / 19 / (number of fluorine atoms in the monomer unit of the fluorine-containing compound)) × 10 6 The number of fluorine atoms in the monomer units of the above fluorine-containing compounds can be determined from the chemical formula of the monomer; for example, in the case of TFE, it is 4. If two or more monomers with different numbers of fluorine atoms are included, the number of fluorine atoms is determined from the monomer unit with the highest fluorine content.

[0088] The manufacturing method disclosed herein may also preferably include a step of purifying the crude product obtained by the above-mentioned mechanochemical treatment to recover the metal fluoride. The purification method is not particularly limited, and known methods can be employed.

[0089] The manufacturing method disclosed herein can be used not only for the production of metal fluorides but also for the decomposition (defluorination) of fluorine-containing compounds.

[0090] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims. [Examples]

[0091] The present disclosure will now be further described with reference to examples, but the present disclosure is not limited to these examples.

[0092] Each value was determined using the following method.

[0093] <Size of fluorine-containing compounds> (Flake-like) The thickness (mm) of the fluorine-containing compound was measured using a micrometer for 20 or more samples, and the average value was taken as the thickness. The long side (mm) and short side (mm) of the fluorine-containing compound were measured using images captured with a Keyence VHX5000 video microscope, and the average values ​​were taken for 90 or more flakes. (powder) Using a laser diffraction / scattering particle size distribution analyzer manufactured by Nikkiso Co., Ltd., measurements were performed in a dry manner at a vacuum pressure of 20 mH2O, and the particle size was considered to be equal to 50% of the integrated particle size distribution (volume-based).

[0094] <Average particle size of grinding aid> The measurement was performed using a laser diffraction / scattering particle size distribution analyzer manufactured by Nikkiso Co., Ltd.

[0095] <Collision energy> Based on the method described in AIChE Journal, Vol.52, No.10, 2006, pp.3421-3426, the following formula was used to determine the result using the simulation software KIK DEM (manufactured by Tohoku University) or UX-DEM (manufactured by JX Metals Corporation).

number

[0096] <Yield of metal fluorides> A mixture of CaF2 and CaO reagents in a predetermined mass ratio was measured by X-ray diffraction (XRD), and a calibration curve was created based on the quantitative values ​​(RIR method) calculated by the analysis. After treatment, XRD measurements were performed on the samples, the amount of CaF2 was calculated from the calibration curve, and the yield of CaF2 (metal fluoride) was calculated.

[0097] <Reaction rate of organofluorine compounds> A 0.5 g sample of the mechanochemically treated product (product containing metal fluoride) obtained in the example was extracted with 10 mL of methanol for 2 hours at 60°C using ultrasound to extract the organofluorine compounds in the sample and obtain the extract. The methanol in the obtained extract was concentrated and analyzed by combustion ion chromatography, and the mass of fluoride ions originating from the organofluorine compounds detected in the extract was measured. Using the mass of fluoride ions measured above, the amount of organic fluorine in the mechanochemically treated material was determined by the following formula. The amount of organic fluorine in mechanochemically treated material (mass ppm) = ((mass of detected fluoride ions) / 0.5 g) × 10 6 The amount of organic fluorine in mechanochemically treated material (molar ppm) = ((mass of detected fluoride ions) / 0.5 g / 19 / (number of fluorine atoms in the monomer unit of the fluorine-containing compound)) × 10 6 Furthermore, the reaction rate of the organofluorine compound was determined using the following formula, based on the amount of organofluorine (by mass) in the mechanochemically treated material obtained above. Reaction rate of organofluorine compounds = ((Amount of fluorine in organofluorine compounds before mechanochemical treatment - Amount of organofluorine in mechanochemically treated product) / Amount of fluorine in organofluorine compounds before mechanochemical treatment) × 100 The amount of fluorine in the organofluorine compound before the above mechanochemical treatment was measured by combustion ion chromatography.

[0098] The following materials (all solid at 25°C) were used in each experimental example. <Fluorine-containing compounds> PTFE:TFE homopolymer, manufactured by Daikin Industries, Ltd. as M18, calcined, in flake form. PVdF:VdF homopolymer, manufactured by Daikin Industries, Ltd. as VP832, in powder form. Fluorine-based telomer: C2F5 (CF2CF2) n -I(5≦n≦10), powder <Metal oxides> CaO (Comparative Example 1): CaO obtained by calcining CaCO3 at 1000°C CaO (Examples 1-6): Calcium oxide (quicklime) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. <Crushing aid> TiO2: Titanium IV oxide, manufactured by Wako Pure Chemical Industries, Ltd., anatase type, former Mohs hardness 6, average particle size 5.8 μm

[0099] Examples 1, 3, and 6 The raw materials (fluorine-containing compounds, metal oxides, and grinding aids) shown in Table 1 were weighed. Approximately half of the steel balls used as grinding media were placed in the pot of the vibrating mill, followed by approximately half of the raw materials. The remaining steel balls were then placed in the pot, followed by the remaining raw materials. A lid was attached to the pot, and the pot was placed in the vibrating mill body. Vibration was started. After mechanochemical treatment for a predetermined time, the product containing metal fluoride (CaF2) was extracted. The impact energy and the yield of metal fluoride were determined using the above method. The results are shown in Table 1. The vibratory mill used for the mechanochemical treatment is as follows: Equipment: MB1 type vibratory mill manufactured by Chuo Kako Co., Ltd. Grinding cylinder: SUS pot (internal volume 3.6L, φ145×225mm) Grinding media: Carbon steel balls (φ35mm), filling rate 80% by volume, filling amount 13kg (approx. 75 pieces) Frequency: 1200 rpm Total amplitude: 8mm Water cooling: None The amount of organofluorine in the mechanochemically treated product obtained in Example 1 was 59 ppm by mass and 0.78 ppm by moles. The reaction rate of the organofluorine compound was 99.95%. The amount of organofluorine in the mechanochemically treated product obtained in Example 6 was 2.3 ppm by mass and 0.06 ppm by molars. The reaction rate of the organofluorine compound was 99.999%.

[0100] Examples 2, 4, and 5 Mechanochemical treatment was performed in the same manner as in Example 1, except that carbon steel balls (φ20 mm) were used as the grinding medium, the filling rate was 80% by volume, and the filling amount was 13 kg (approximately 403 balls). The results are shown in Table 1.

[0101] Comparative Example 1 The raw materials (fluorine-containing compounds, metal oxides) shown in Table 1 were weighed. The raw materials and zirconia balls, used as grinding media, were placed in the pot of the planetary mill. The lid was attached to the pot, and the pot was placed in the planetary mill body, and rotation was started. After mechanochemical treatment for a predetermined time, the product containing metal fluoride (CaF2) was extracted. The collision energy and the yield of metal fluoride were determined using the above method. The results are shown in Table 1. The planetary mills used in the mechanochemical treatment are as follows: Equipment: Fritsch Pulverisette planetary ball mill P-7 Grinding cylinder: Zirconia pot (internal volume 45 mL, φ40 mm) Grinding medium: Zirconia balls (φ15mm), 7 pieces, 80% volume filling rate

[0102] [Table 1] In the table, "Sample Size" refers to the average particle diameter if the sample is in powder form.

[0103] The results from the examples showed that a good reaction rate was obtained when 10 g or more of a fluorine-containing compound was treated mechanochemically, indicating that metal fluorides can be industrially mass-produced by mechanochemical treatment.

Claims

1. A method for producing a metal fluoride, comprising the step of obtaining a metal fluoride by mechanochemically treating 10 g or more of a fluorine-containing compound with at least one metal oxide selected from the group consisting of alkali metal oxides and alkaline earth metal oxides.

2. The manufacturing method according to claim 1, wherein the mechanochemical treatment is performed by applying an energy of 1.5 J / s / g or more.

3. The manufacturing method according to claim 1 or 2, wherein the mechanochemical treatment is performed by applying an energy of 1.8 to 10.0 J / s / g.

4. The manufacturing method according to claim 1 or 2, wherein the mechanochemical treated product obtained by the mechanochemical treatment substantially does not contain organic fluorine.

5. The manufacturing method according to claim 1 or 2, wherein the mechanochemical treatment is performed without using a planetary mill.

6. The manufacturing method according to claim 1 or 2, wherein the mechanochemical treatment is performed using a vibrating mill.

7. The manufacturing method according to claim 1 or 2, wherein the mechanochemical treatment is performed using a pulverized medium having a length of at least 15 mm in one dimension.

8. The manufacturing method according to claim 1 or 2, wherein the mechanochemical treatment is performed using a pulverized medium having a three-dimensional length of 30 to 40 mm.

9. The manufacturing method according to claim 1 or 2, wherein the mechanochemical treatment is performed in the presence of a grinding aid having a prior Mohs hardness of 5 to 8.

5.

10. The manufacturing method according to claim 9, wherein the pulverizing aid is titanium dioxide.

11. The manufacturing method according to claim 9, wherein the grinding aid is composed of particles with an average particle size of 5 to 10 μm.

12. The manufacturing method according to claim 9, wherein the amount of the grinding aid used is 0.5 to 3 equivalents per equivalent of the fluorine-containing compound.

13. The manufacturing method according to claim 1 or 2, wherein the metal oxide is calcium oxide.

14. The manufacturing method according to claim 1 or 2, wherein the amount of the metal oxide used is 1 to 10 equivalents per equivalent of the fluorine-containing compound.

15. The method for producing a fluorine-containing compound according to claim 1 or 2, wherein the fluorine-containing compound is a fluorine-containing low molecular weight compound with a molecular weight of 2000 or less.

16. The method for producing the product according to claim 1 or 2, wherein the fluorine-containing compound is a fluorine-containing polymer.

17. The method for producing the product according to claim 1 or 2, wherein the fluorine-containing compound is at least one selected from the group consisting of polytetrafluoroethylene, polydifluoroethylene, and fluorine-based telomers.

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