Metal acid compounds contain liquid

Abstract

To provide a metal acid compound-containing liquid which is excellent in film-forming property or adhesion to various base materials, especially, a plastic film base material.SOLUTION: A metal acid compound-containing liquid has one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si and rare earth elements, a resin and a catalyst, wherein a particle diameter D50 by particle diameter distribution measurement using a dynamic light scattering method is 1,000 nm or less. The metal acid compound-containing liquid has one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si and rare earth elements, a resin and a catalyst, wherein a maximum value of transmittance in a wavelength region ranging from 550 nm to 700 nm is 70%T or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a liquid containing a metal acid compound. [Background technology]

[0002] Coating agents containing rare metals and metalloid elements such as niobium (Nb), tantalum (Ta), titanium (Ti), molybdenum (Mo), tungsten (W), zirconium (Zr), hafnium (Hf), silicon (Si), and rare earth elements can be applied to the surface of a substrate to form a thin film, thereby imparting functions according to the application. For example, niobium oxide has a high refractive index and dielectric constant, and is therefore used as a semiconductor material, surface protectant, anti-reflective agent, refractive index modifier, catalyst, etc. To form a thin film containing niobium oxide on the surface of various parts, there is a niobium aqueous solution in which fine particles made of a niobium acid compound are dispersed in a dispersion medium, as disclosed in Patent Document 1. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2022 / 138539 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, niobium aqueous solutions, such as those disclosed in Patent Document 1, sometimes exhibited insufficient adhesion to the substrate, even if they could form a uniform thin film on the substrate surface, depending on the material of the component's surface, resulting in easy peeling. In particular, there were issues with film formation and adhesion to plastic films such as PET.

[0005] In view of the above problems, the present invention aims to provide a metal acid compound-containing liquid that exhibits excellent film-forming properties or adhesion to a variety of substrates, particularly plastic film substrates. [Means for solving the problem]

[0006] The present invention, which was developed to solve the above problems, comprises one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements, a resin, and a solvent, and is characterized in that the particle size D50 measured by dynamic light scattering is 1000 nm or less. The metal acid compound-containing liquid of the present invention comprises one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements, a resin, and a solvent. The particle size distribution (D50) measured using dynamic light scattering is 1000 nm or less, resulting in excellent film-forming properties and adhesion to a variety of substrates, particularly plastic film substrates.

[0007] The metal acid compounds in the metal acid compound-containing solution of the present invention are presumed to exist in the solution as polymetallic acid polynuclear complex ions formed by multi-stage condensation of one or more metal atoms selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements, or a metalloid atom and an oxygen atom in the containing solution. Furthermore, these metal acid compounds also include those that exist in the containing solution as ions in which these metal oxides are ionically bonded with alkali metals such as lithium. In this specification, unless otherwise specified, Si acid compounds will be described as metal acid compounds.

[0008] Furthermore, the metal acid compound-containing liquid of the present invention comprises a resin and a solvent. The resin uniformly miscibles with the metal acid compound and adheres to the substrate, thereby improving film-forming properties and adhesion to various substrates, such as plastic film substrates. Examples of resins contained in the metal acid compound-containing liquid include polyolefin compounds and polyvinyl compounds. The resins contained in the metal acid compound-containing liquid of the present invention will be described further later.

[0009] Furthermore, in particle size distribution measurements using dynamic light scattering, it is preferable that the particle size D50 of the particles in the metal acid compound-containing liquid of the present invention is 1000 nm or less, from the viewpoint of good film formation on the substrate. In addition, it is preferable that the particle size (D50) of the particles in the metal acid compound-containing liquid is even smaller, as this results in less change over time and is more stable, and also from the viewpoint of forming a good coating film without any uncovered areas during film formation and ensuring a sufficient film weight. The particle size (D50) of the particles in the metal acid compound-containing liquid is more preferably 900 nm or less, even more preferably 800 nm or less, particularly preferably 700 nm or less, even more preferably 600 nm or less, even more preferably 500 nm or less, particularly preferably 400 nm or less, even more preferably 300 nm or less, even more preferably 200 nm or less, even more preferably 100 nm or less, even more preferably 80 nm or less, even more preferably 50 nm or less, particularly preferably 30 nm or less, even more preferably 20 nm or less, even more preferably 10 nm or less, even more preferably 5 nm or less, and most preferably 3 nm or less. Thus, the "metal acid compound-containing liquid" of the present invention is defined as a liquid in which the particle size (D50) of the particles in the metal acid compound-containing liquid of the present invention is 1000 nm or less as measured by dynamic light scattering.

[0010] Here, dynamic light scattering is a method that involves irradiating a solution, such as a suspension, with light, such as laser light, and measuring the light scattering intensity from a group of particles undergoing Brownian motion. The particle size and distribution are then determined from the temporal variation of this intensity. Specifically, the particle size distribution is evaluated using a zeta potential, particle size, and molecular weight measurement system (Otsuka Electronics Co., Ltd.: ELSZ-2000ZS) in accordance with JIS Z 8828:2019 "Particle size analysis - Dynamic light scattering method". Immediately before measurement, the solution to be measured is filtered through a 2 μm pore size filter to remove dust and other particles, and then ultrasonic treatment is performed at 28 kHz for 3 minutes using an ultrasonic cleaner (AS ONE Corporation: VS-100III). The particle size (D50) refers to the median diameter (D50), which is the particle size that shows the 50% integrated value of the integrated distribution curve. Furthermore, unless otherwise specified in this specification, "particle size (D50)" includes both "initial particle size D50," which indicates the particle size (D50) of particles in the metal acid compound-containing solution of the present invention immediately after its production, when the liquid temperature is adjusted to 25°C, and "particle size over time D50," which indicates the particle size (D50) of particles in the metal acid compound-containing solution of the present invention after it has been left to stand for 20 days from the day it was produced in a constant temperature incubator set to room temperature of 25°C.

[0011] In this invention, the term "containing liquid" is not limited to a solution in which the solute is dispersed or mixed in a solvent as a single molecule, but also includes a solution in which aggregates of multiple molecules attracted by intermolecular interactions, such as (1) polymer molecules, (2) solvated molecules, (3) molecular clusters, or (4) colloidal particles, are dispersed in the solvent.

[0012] Furthermore, the metal acid compound-containing liquid of the present invention comprises one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements, a resin, and a solvent, and is characterized in that the maximum transmittance in the wavelength range of 550 nm to 700 nm is 70%T or higher. The metal acid compound-containing liquid of the present invention comprises one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements, a resin, and a solvent, and has a maximum transmittance of 70%T or more in the wavelength range of 550 nm to 700 nm, thereby exhibiting excellent film-forming properties or adhesion to various substrates, particularly plastic film substrates.

[0013] The metal acid compound, resin, and solvent in the metal acid compound-containing solution of the present invention are as described above, so their explanation is omitted.

[0014] Furthermore, the metal acid compound-containing liquid of the present invention is preferable if the maximum transmittance in the wavelength range of 550 nm to 700 nm is 70% T or higher, as this indicates high dispersion and excellent uniformity of components in the liquid. It is more preferable if the maximum transmittance in the wavelength range of 550 nm to 700 nm is 75% T or higher, even more preferable if it is 80% T or higher, particularly preferable if it is 85% T or higher, even more preferable if it is 90% T or higher, even more preferable if it is 95% T or higher, particularly preferable if it is 98% T or higher, even more preferable if it is 99% T or higher, and most preferable if it is 100% T. If the measured value exceeds 100% T due to measurement errors of the spectrophotometer used to measure the transmittance, it shall be considered as 100% T.

[0015] Furthermore, the metal acid compound-containing solution of the present invention preferably has a transmittance of 70%T or higher at least one of the wavelengths of 550nm, 600nm, 650nm, and 700nm, more preferably 75%T or higher, even more preferably 80%T or higher, particularly preferably 85%T or higher, even more preferably 90%T or higher, even more preferably 95%T or higher, particularly preferably 98%T or higher, even more preferably 99%T or higher, and most preferably 100%T. If the measured value exceeds 100%T due to measurement errors of the spectrophotometer used to measure the transmittance, it shall be considered as 100%T.

[0016] Furthermore, the metal oxide compound-containing liquid of the present invention preferably has a minimum transmittance in the wavelength range of 550 nm to 700 nm of 70%T or more, more preferably 75%T or more, even more preferably 80%T or more, particularly preferably 85%T or more, further preferably 90%T or more, even more preferably 95%T or more, particularly preferably 98%T or more, still more preferably 99%T or more, and most preferably 100%T. When the measured value exceeds 100%T due to measurement errors of the spectrophotometer used for the transmittance measurement, it is regarded as 100%T.

[0017] Thus, the metal oxide compound-containing liquid of the present invention is defined as a liquid having a maximum transmittance of 70%T in the wavelength range of 550 nm to 700 nm as the "metal oxide compound-containing liquid" of the present invention. In addition, in this specification, unless otherwise specified, the "transmittance" refers to both the "initial transmittance" indicating the transmittance of the metal oxide compound-containing liquid of the present invention adjusted to a liquid temperature of 25°C immediately after generation, and the "transmittance over time" indicating the transmittance of the metal oxide compound-containing liquid after standing for one month from the day when the metal oxide compound-containing liquid of the present invention was generated in a thermostat set at a room temperature of 25°C.

[0018] Here, the transmittance in the wavelength range of 550 nm to 700 nm is measured for the metal oxide compound-containing liquid of the present invention in accordance with the following transmittance measurement conditions, conforming to JIS K 0115, 2004 "General Rules for Absorption Photometric Analysis Methods" using a spectrophotometer.

[0019] =Transmittance Measurement Conditions= · Measuring device: UV-visible near-infrared spectrophotometer UH4150 type (manufactured by Hitachi High-Tech Science Corporation) · Measurement mode: Wavelength scan · Data mode: %T (transmission) · Measurement wavelength range: 200 nm to 2000 nm · Scan speed: 600 nm / min · Sampling interval: 2 nm

[0020] Furthermore, the metal acid compound-containing liquid of the present invention is characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin. If the resin contained in the metal acid compound-containing liquid of the present invention is an anionic water-soluble resin and / or a nonionic water-soluble resin, the anionic water-soluble resin and / or nonionic water-soluble resin uniformly mix with the above-mentioned metal acid compound and adhere to the substrate, thereby improving film-forming properties and adhesion to the plastic film substrate.

[0021] Here, a cationic water-soluble resin is a resin in which the polymer contains a functional group that has a positive charge in water at pH=7, such as an amino group, imino group, tertiary amine group, quaternary ammonium group, or hydrazino group. Anionic water-soluble resin is a resin in which the polymer contains a functional group that has a negative charge in water at pH=7, such as a carboxyl group, sulfone group, sulfate ester group, or phosphate ester group. Furthermore, a nonionic water-soluble resin is a resin that does not fall under the above categories of cationic or anionic water-soluble resins, and in which the polymer contains a functional group such as a hydroxyl group, ether group, or amide group.

[0022] Furthermore, it is preferable that these resins contain one or more water-soluble homopolymers selected from the group consisting of acrylic polymers, urethane polymers, styrene polymers, olefin polymers, amide polymers, siloxane polymers, epoxy polymers, vinyl chloride polymers, and vinyl acetate polymers, and / or water-soluble copolymers composed of two or more of these polymers. In particular, it is preferable that they contain one or more water-soluble homopolymers of acrylic polymers, styrene polymers, and olefin polymers, and / or water-soluble copolymers composed of two or more of these polymers.

[0023] Furthermore, the metal acid compound-containing liquid of the present invention is characterized in that the metal acid content in the metal acid compound-containing liquid is 0.1% by mass or more and 50% by mass or less in terms of metal. It is preferable that the metal acid content in the metal acid compound-containing liquid of the present invention is 0.1% by mass or more and 50% by mass or less in terms of metal, as this improves the stability of the metal acid compound-containing liquid of the present invention. It is more preferable that the metal acid content in the metal acid compound-containing liquid is 0.1% by mass or more and 45% by mass or less in terms of metal, even more preferable that it is 0.15% by mass or more and 40% by mass or less, particularly preferable that it is 0.15% by mass or more and 35% by mass or less, even more preferable that it is 0.15% by mass or more and 30% by mass or less, even more preferable that it is 0.1% by mass or more and 25% by mass or less, particularly preferable that it is 0.15% by mass or more and 20% by mass or less, and most preferable that it is 0.15% by mass or more and 15% by mass or less. Note that the metal acid content in the metal acid compound-containing liquid of the present invention can also be expressed in terms of oxide rather than metal, and the metal acid content expressed in terms of oxide will be larger by the amount equivalent to oxygen.

[0024] Here, the metallic acid content in the metallic acid compound-containing solution of the present invention is calculated by appropriately diluting the solution with dilute hydrochloric acid as needed, and measuring the total mass fraction of one or more metallic acids selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements in terms of metal equivalent, using high-frequency inductively coupled plasma emission spectrometry (ICP emission spectrometry (Agilent Technologies: AG-5110)) in accordance with JIS K0116:2014.

[0025] Furthermore, the metal acid compound-containing liquid of the present invention is characterized in that the resin content in the metal acid compound-containing liquid is 0.1% by mass or more and 60% by mass or less. It is preferable that the resin content in the metal acid compound-containing liquid of the present invention is 0.1% by mass or more and 60% by mass or less, in that it can suppress the aggregation of fine metal acid compounds. It is more preferable that the resin content is 0.15% by mass or more and 40% by mass or less, even more preferable that it is 0.2% by mass or more and 30% by mass or less, and particularly preferable that it is 0.25% by mass or more and 20% by mass or less.

[0026] Here, the resin content in the metal acid compound-containing liquid of the present invention can be determined, for example, as follows: The metal acid compound-containing liquid of the present invention is dried in an air atmosphere at 100°C to 200°C, and the solid content of the resulting dried product is measured. Then, the dried product is calcined in an air atmosphere at 500°C to 1000°C, and the resin component of the dried product is volatilized, and the solid content of the resulting calcined product is measured. The difference between the solid content of the dried product and the solid content of the calcined product can then be calculated as the resin content in the metal acid compound-containing liquid of the present invention. Alternatively, it can also be calculated by liquid chromatography (LC) or gel permeation chromatography (GPC).

[0027] Furthermore, the metal acid compound-containing solution of the present invention is characterized in that the solvent is water. The metal acid compound-containing solution of the present invention has high dispersibility in water and good solubility in water, so water can be used as a solvent. Furthermore, organic solvents can be used as long as they do not impair solubility in water, and a mixed solvent of water and an organic solvent can also be used. Examples of organic solvents include alcohol-based solvents and ketone-based solvents, and one or more selected from methanol, ethanol, propanol, isopropyl alcohol, ethylene glycol, polypropylene glycol, glycerin, acetone, methyl ethyl ketone, etc., can also be used.

[0028] Furthermore, the metal acid compound-containing solution of the present invention is characterized in that the pH of the metal acid compound-containing solution is greater than 7. A pH greater than 7 of the metal acid compound-containing solution of the present invention is preferable in that it improves the stability of the metal acid compound-containing solution of the present invention. Furthermore, a pH of 7.5 or higher is more preferable, 8 or higher is even more preferable, and 8.5 or higher is particularly preferable. On the other hand, a pH of 13 or lower is preferable, 12.5 or lower is more preferable, and 12 or lower is even more preferable. In this specification, unless otherwise specified, "pH" refers to both the "initial pH" of the metal acid compound-containing solution of the present invention adjusted to a liquid temperature of 25°C immediately after production, and the "time-dependent pH" of the metal acid compound-containing solution after being left standing for one month from the day it was produced in a constant temperature incubator set to room temperature of 25°C.

[0029] Here, the pH of the metal acid compound-containing solution of the present invention is measured by immersing the electrode (HORIBA Standard ToupH electrode 9615S-10D) of a pH meter (HORIBA Glass Electrode Type Hydrogen Ion Concentration Indicator D-51) in the metal acid compound-containing solution of the present invention, and after confirming that the liquid temperature has stabilized at 25°C, the measurement is performed.

[0030] Furthermore, the metal acid compound-containing liquid of the present invention is characterized by further containing ammonia. In the present invention, the metal acid compound-containing liquid is produced during the manufacturing process by a reverse neutralization method in which an acidic metal acid solution is added to ammonia water. Therefore, it is believed that ammonia containing ammonium ions is present as a cation in the containing liquid.

[0031] Methods for measuring the ammonia concentration in the contained liquid include adding sodium hydroxide to the contained liquid, distilling and separating the ammonia, and then quantifying the ammonia concentration using an ion meter; quantifying the N2 content in the gasified sample using a thermal conductivity meter; the Kjeldahl method; gas chromatography (GC); ion chromatography; and gas chromatography-mass spectrometry (GC-MS). In particular, the quantification method using an ion meter is preferred.

[0032] The ammonia concentration of the ammonia containing ammonium ions in the metal acid compound-containing liquid of the present invention is preferably 0.001% by mass or more and 25% by mass or less, and more preferably 0.003% by mass or more and 15% by mass or less. The ammonia concentration may also be 0.1% by mass or more and 10% by mass or less, 0.5% by mass or more and 10% by mass or less, or 1% by mass or more and 8% by mass or less.

[0033] Furthermore, the metal acid compound-containing solution of the present invention is characterized by further containing an organic nitrogen compound and / or hydrogen peroxide. Since the metal acid compound contained in the metal acid compound-containing solution of the present invention is produced using an organic nitrogen compound and / or hydrogen peroxide solution, the metal acid compound-containing solution of the present invention may also contain an organic nitrogen compound and / or hydrogen peroxide solution.

[0034] It is presumed that the organic nitrogen compound in the metal acid compound-containing solution of the present invention exists in the solution as an ion bonded to the metal acid.

[0035] Examples of organic nitrogen compounds include aliphatic amines, aromatic amines, amino alcohols, amino acids, polyamines, quaternary ammonium compounds, guanidine compounds, and azole compounds.

[0036] Examples of aliphatic amines include methylamine, dimethylamine, trimethylamine, ethylamine, methylethylamine, diethylamine, triethylamine, methyldiethylamine, dimethylethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, iso-propylamine, diiso-propylamine, triiso-propylamine, n-butylamine, di-n-butylamine, tri-n-butylamine, iso-butylamine, diiso-butylamine, triiso-butylamine, and tert-butylamine, n-pentaamine, n-hexylamine, cyclohexylamine, and piperidine.

[0037] Examples of aromatic amines include aniline, phenylenediamine, and diaminotoluene. Furthermore, examples of amino alcohols include methanolamine, ethanolamine, propanolamine, butanolamine, pentanolamine, dimethanolamine, diethanolamine, trimethanolamine, methylmethanolamine, methylethanolamine, methylpropanolamine, methylbutanolamine, ethylmethanolamine, ethylethanolamine, ethylpropanolamine, dimethylmethanolamine, dimethylethanolamine, dimethylpropanolamine, methyldimethanolamine, methyldiethanolamine, diethylmethanolamine, trishydroxymethylaminomethane, bis(2-hydroxyethyl)aminotris(hydroxymethyl)methane, and aminophenol. Examples of amino acids include alanine, arginine, aspartic acid, and EDTA. Furthermore, examples of polyamines include polyamines and polyetheramines.

[0038] Examples of quaternary ammonium compounds include alkylimidazolium, pyridinium, pyrrolidium, and tetraalkylammonium. Specific examples of alkylimidazolium include 1-methyl-3-methylimidazolium, 1-ethyl-3-methylimidazolium, 1-propyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-methyl-2,3-dimethylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1-propyl-2,3-dimethylimidazolium, and 1-butyl-2,3-dimethylimidazolium. Furthermore, specific examples of pyridinium and pyrrolidium include N-butylpyridinium, N-ethyl-3-methylpyridinium, N-butyl-3-methylpyridinium, N-hexyl-4-(dimethylamino)pyridinium, N-methyl-1-methylpyrrolidinium, and N-butyl-1-methylpyrrolidinium. In addition, specific examples of tetraalkylammonium include tetramethylammonium, tetraethylammonium, tetrabutylammonium, ethyl-dimethylpropylammonium, and choline. The anions that form salts with the above-mentioned cations include OH - Cl - , Br - , I - BF4 - HSO4 - These are some examples.

[0039] Examples of guanidine compounds include guanidine, diphenylguanidine, and ditolylguanidine. Examples of azole compounds include imidazole compounds and triazole compounds. Specific examples of imidazole compounds include imidazole, 2-methylimidazole, and 2-ethyl-4-methylimidazole. Specific examples of triazole compounds include 1,2,4-triazole, 1,2,4-triazole-3-methylcarboxylate, and 1,2,3-benzotriazole.

[0040] Here, the organic nitrogen compound is preferably an aliphatic amine because it is highly volatile and has low toxicity. Specifically, it is more preferably an aliphatic amine having 1 to 4 carbon atoms, and particularly preferably an aliphatic amine having 1 to 2 carbon atoms. Examples include methylamine and dimethylamine.

[0041] Furthermore, the organic nitrogen compound is preferably a quaternary ammonium compound because it not only has high solubility but also exhibits high crystallization inhibition and high sol formation inhibition. For example, tetraalkylammonium salts are preferred, tetraalkylammonium hydroxide salts are more preferred, tetramethylammonium hydroxide and tetraethylammonium hydroxide are particularly preferred, and tetramethylammonium hydroxide (TMAH) is also particularly preferred.

[0042] Furthermore, the organic nitrogen compound may be a mixture of two or more compounds, rather than just one selected from aliphatic amines, aromatic amines, amino alcohols, amino acids, polyamines, quaternary ammonium compounds, guanidine compounds, and azole compounds. For example, a mixture of aliphatic amines and quaternary ammonium compounds is preferable because it allows for increased solubility while keeping the amount added low to avoid increasing toxicity.

[0043] Specifically, examples include mixtures of two organic nitrogen compounds, such as methylamine and tetramethylammonium hydroxide (TMAH), dimethylamine and tetramethylammonium hydroxide (TMAH), and methylamine and dimethylamine, as well as mixtures of three organic nitrogen compounds, such as methylamine, dimethylamine, and tetramethylammonium hydroxide (TMAH).

[0044] Methods for measuring the concentration of organic nitrogen compounds present in the metal acid compound-containing solution of the present invention include gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-mass spectrometry (LC-MS). In particular, measurement by liquid chromatography (LC) and liquid chromatography-mass spectrometry (LC-MS) is preferred.

[0045] As described above, it is preferable that the organic nitrogen compound contained in the metal acid compound-containing liquid of the present invention is an aliphatic amine such as methylamine, dimethylamine, ethylamine, trimethylamine, or a mixture thereof, or a quaternary ammonium compound such as tetramethylammonium hydroxide (TMAH) or tetraethylammonium hydroxide (TEAH).

[0046] The present invention provides a method for detecting hydrogen peroxide in a metal acid compound-containing solution. For example, by using the standard addition method, the hydrogen peroxide content in the solution can be confirmed by measuring the relative absorbance intensity with that of a standard solution of hydrogen peroxide. Specifically, by examining the ultraviolet-visible absorption spectra of a standard solution containing a known concentration, for example, 1% by mass of hydrogen peroxide, and a standard solution without added hydrogen peroxide, a wavelength region in which a change in absorbance associated with peroxo complex formation is observed can be identified. If the difference in absorbance between the standard solution without added hydrogen peroxide and a sample with an unknown hydrogen peroxide concentration in that wavelength region is less than 1%, it can be confirmed that the sample with an unknown hydrogen peroxide concentration substantially does not contain hydrogen peroxide. When hydrogen peroxide is present in the solution, it reacts with the metal polyacid to form a peroxo complex. Therefore, as described above, by checking the difference in absorbance with the standard solution without added hydrogen peroxide, it can be confirmed that the solution does not contain hydrogen peroxide. In addition to the standard addition method described above, qualitative and quantitative analysis of hydrogen peroxide in the solution may also be performed by, for example, using a commercially available hydrogen peroxide measurement kit to add a reagent that reacts with hydrogen peroxide to the solution and measure the resulting color change, or by adding a reagent that reacts with hydrogen peroxide to the solution and measure the resulting luminescence.

[0047] Furthermore, the metal acid compound-containing solution of the present invention may also contain a high-boiling-point solvent. The high-boiling-point solvent is preferably a solvent with a boiling point of 180°C or higher at 1 atmosphere, and examples include polyhydric alcohol-based solvents and glycol-based solvents.

[0048] Here, polyhydric alcohol solvents include glycerin (boiling point: 290°C), 1,6-hexanediol (boiling point: 250°C), and 1,7-heptanediol (boiling point: 259°C). Glycol solvents include ethylene glycol (boiling point: 197.3°C), propylene glycol (boiling point: 188.2°C), diethylene glycol (boiling point: 244.3°C), triethylene glycol (boiling point: 287.4°C), oligoethylene glycol (boiling point: 287°C to 460°C), polyethylene glycol (PEG) (boiling point: above 460°C), and polyethylene glycol (PEG)-polypropylene glycol (PPG) copolymer (boiling point: 460°C). Examples include diethylene glycol monohexyl ether (boiling point: 260°C), polyoxyalkylene monoalkyl ether (boiling point: 260°C or higher), polyoxyethylene sorbitan monolaurate (boiling point: 321°C or higher), other anionic fluorinated surfactants (boiling point: 180°C or higher), amphoteric fluorinated surfactants (boiling point: 180°C or higher), nonionic fluorinated surfactants (boiling point: 180°C or higher), amine oxides (boiling point: 180°C or higher), etc. Glycerin is particularly preferred. The boiling points mentioned above are the boiling points at 1 atmosphere.

[0049] Furthermore, because high-boiling-point solvents have a high boiling point, if their boiling point at 1 atmosphere is excessively high, the high-boiling-point solvent may decompose before boiling, making it impossible to accurately measure the boiling point. In such cases, the boiling point under reduced pressure may be measured, and the boiling point at 1 atmosphere may be converted using a general-purpose boiling point conversion table.

[0050] Furthermore, the metal acid compound-containing liquid of the present invention may contain, to the extent that it does not inhibit its effects, components derived from one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements, as well as components other than those derived from resins, ammonia, organic nitrogen compounds, and hydrogen peroxide ("other components"), as unavoidable impurities.

[0051] Furthermore, the metal acid compound-containing liquid of the present invention may contain dispersants, pH adjusters, colorants, thickeners, wetting agents, binder resins, etc., as appropriate for the application.

[0052] Furthermore, the composite metal acid compound-containing solution of the present invention is characterized by comprising the metal acid compound-containing solution of the present invention and at least one element A selected from the group consisting of Li, Na, Ma, Al, K, Ca, V, Mn, Fe, Co, Ni, Cu, Zn, Sn, Sr, and Ba. It is presumed that the composite metal acid compound-containing liquid of the present invention contains ions in which the metal acid compound of the present invention and element A are ionically bonded.

[0053] The compound may contain, as element A, compounds such as Li, Na, Mg, Al, K, Ca, V, Mn, Fe, Co, Ni, Cu, Zn, Sn, Sr, and Ba. Here, examples of compounds include oxides, alkali metal salts of metal acids, alkaline earth metal salts of metal acids, chlorides, alkoxides of metal acids, and polyoxometalates. Furthermore, the content of element A in the composite metal acid compound-containing liquid of the present invention is such that, when X is the total number of moles of each element A in terms of metal equivalent, the molar ratio X / M of the total number of moles of each element A in terms of metal equivalent to the total number of moles of one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements in terms of metal equivalent is greater than 0 to 3.0, and more preferably between 0.0002 and 2.0. Furthermore, the molar ratio X / M may be 0.001 to 1.0, 0.005 to 0.8, 0.01 to 0.5, 0.1 to 0.4, or 0.2 to 0.3. Moreover, since the complex metal acid compound-containing solution of the present invention is a homogeneous solution, even if these compounds are in a suspended state, improved uniformity and reactivity (reaction rate) can be expected. In addition, if these compounds dissolve in the complex metal acid compound-containing solution of the present invention and become a homogeneous solution, the most reactive state can be achieved.

[0054] The metal acid compound-containing film of the present invention is characterized by containing the metal acid compound and a resin in the metal acid compound-containing liquid of the present invention described above. The metal acid compound-containing film of the present invention includes a dried film obtained by applying the metal acid compound-containing liquid of the present invention to the surface of a substrate and then drying it, for example by vacuum drying, and a calcined film obtained by calcining the obtained dried film. Furthermore, the metal acid compound-containing film of the present invention also includes metal acid compound-containing films with different physical properties, such as crystal structure, which are produced by drying the metal acid compound-containing film of the present invention, for example by vacuum drying or calcination, and may have an amorphous structure, a single-crystal structure, or a polycrystalline structure. The method for producing the metal acid compound-containing film of the present invention will be described later.

[0055] Furthermore, the composite metal acid compound-containing film of the present invention is characterized by containing composite metal acid compound particles contained in a composite metal acid compound-containing liquid. The composite metal acid compound-containing film of the present invention includes a dried film obtained by applying the composite metal acid compound-containing liquid of the present invention to the surface of a substrate and then drying it, for example by vacuum drying, and a calcined film obtained by further calcining the obtained dried film. Furthermore, the composite metal acid compound-containing film of the present invention also includes metal acid compound-containing films with different physical properties, such as crystal structure, which are produced by vacuum drying or calcining the composite metal acid compound-containing liquid of the present invention, and may have an amorphous structure, a single crystal structure, or a polycrystalline structure.

[0056] The coating agent of the present invention is characterized by containing the above-described metal acid compound-containing liquid of the present invention. The coating agent of the present invention contains a metal acid compound-containing solution that has high dispersibility in water, good solubility in water, and excellent storage stability. For example, by applying it to the surface of a substrate such as metal, ceramic, glass, and plastic film, it is possible to form a uniform coating film.

[0057] The method for producing the metal acid compound-containing liquid of the present invention described above will be explained below.

[0058] The present invention provides a method for producing a metal acid compound-containing liquid by weighing one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements, a resin, and a solvent in predetermined proportions, mixing them, and stirring for 30 minutes to obtain the metal acid compound-containing liquid of the present invention.

[0059] Herein, the method for producing a niobium-containing liquid, which is a metal acid compound used in the method for producing a metal acid compound-containing liquid of the present invention, will be described below.

[0060] A method for producing a niobium-containing liquid comprises the steps of: generating an acidic niobium solution containing niobium; obtaining a niobium-containing precipitate slurry by a reverse neutralization method in which the acidic niobium solution is added to aqueous ammonia; and stirring a mixture obtained by mixing the niobium-containing precipitate slurry with at least one selected from amine and ammonia to obtain a niobium-containing liquid.

[0061] In the process of producing an acidic niobium solution containing niobium, the acidic niobium solution refers to an acidic niobium solution containing fluoride ions obtained by solvent extraction of a solution in which niobium is dissolved in an acidic solution containing hydrofluoric acid.

[0062] Here, it is preferable to adjust the acidic niobium solution containing fluoride ions, such as an aqueous solution of niobium fluoride, by adding water (e.g., pure water) so that it contains 1 to 100 g / L of niobium in terms of Nb2O5. In this case, a niobium concentration of 1 g / L or more in terms of Nb2O5 is preferable because it results in a water-soluble niobium compound hydrate, and from the perspective of productivity, 10 g / L or more is more preferable, and 20 g / L or more is even more preferable. On the other hand, a niobium concentration of 100 g / L or less in terms of Nb2O5 is also preferable because it results in a water-soluble niobium compound hydrate, and to more reliably synthesize a water-soluble niobium compound hydrate, it is more preferable to have a concentration of 90 g / L or less, even more preferable to have a concentration of 80 g / L or less, and particularly preferable to have a concentration of 70 g / L or less. The pH of the aqueous solution of niobium fluoride is preferably 2 or less, and more preferably 1 or less, from the viewpoint of completely dissolving niobium or niobium oxide.

[0063] Next, in the step of obtaining a precipitate slurry containing niobium by a reverse neutralization method in which the acidic niobium solution is added to ammonia water (hereinafter referred to as the reverse neutralization step), it is preferable to obtain a precipitate slurry containing niobium by adding an acidic niobium solution containing fluoride ions to ammonia water of a predetermined concentration, i.e., by a reverse neutralization method.

[0064] The ammonia concentration of the ammonia solution used for reverse neutralization is preferably 10% to 30% by mass. A concentration of 10% by mass reduces the likelihood of undissolved niobium, allowing for complete dissolution of niobium or niobic acid in water. On the other hand, a concentration of 30% by mass or less is preferable because it is close to a saturated aqueous solution of ammonia.

[0065] From this viewpoint, the ammonia concentration of the aqueous ammonia solution is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass. On the other hand, the ammonia concentration is preferably 30% by mass or less, more preferably 29% by mass or less, and even more preferably 28% by mass or less.

[0066] During the reverse neutralization step, the amount of niobium fluoride aqueous solution added to the ammonia water preferably results in a molar ratio of NH3 / Nb2O5 of 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the viewpoint of generating amines and niobium acid compounds soluble in dilute ammonia water, the amount of niobium fluoride aqueous solution added to the ammonia water preferably results in a molar ratio of NH3 / HF of 3.0 or higher, more preferably 4.0 or higher, and even more preferably 5.0 or higher. On the other hand, from the viewpoint of cost reduction, the molar ratio of NH3 / HF preferably results in a molar ratio of 100 or lower, more preferably 50 or higher, and even more preferably 40 or higher.

[0067] In the reverse neutralization step, the time required for adding the niobium fluoride aqueous solution to the ammonia water is preferably within 1 minute, more preferably within 30 seconds, and even more preferably within 10 seconds. In other words, rather than gradually adding the niobium fluoride aqueous solution over time, it is preferable to add it to the ammonia water in the shortest possible time, for example, by adding it all at once, to allow the neutralization reaction to occur. Furthermore, since the acidic niobium fluoride aqueous solution is added to the alkaline ammonia water in the reverse neutralization step, the neutralization reaction can be carried out while maintaining a high pH. Note that the niobium fluoride aqueous solution and ammonia water can be used at room temperature.

[0068] Furthermore, the method for producing the niobium-containing solution includes a step of removing fluoride ions from the niobium-containing precipitate slurry obtained by the reverse neutralization method to obtain a niobium-containing precipitate from which fluoride ions have been removed. Since the niobium-containing precipitate slurry obtained by the reverse neutralization method contains fluorine compounds such as ammonium fluoride as impurities, it is preferable to remove these.

[0069] The method for removing fluorine compounds is arbitrary, but methods such as reverse osmosis filtration using ammonia water or pure water, ultrafiltration, microfiltration using membranes, centrifugation, and other known methods can be employed. When removing fluoride ions from a precipitate slurry containing niobium, temperature control is not particularly necessary, and the process may be carried out at room temperature.

[0070] Specifically, a niobium-containing precipitate slurry obtained by the reverse neutralization method is decanted using a centrifuge, and the washing process is repeated until the amount of free fluoride ions is 100 mg / L or less, thereby obtaining a niobium-containing precipitate from which fluoride ions have been removed.

[0071] The cleaning liquid used for removing fluoride ions is preferably aqueous ammonia. Specifically, aqueous ammonia of 5.0% by mass or less is preferred, aqueous ammonia of 4.0% by mass or less is more preferred, aqueous ammonia of 3.0% by mass or less is even more preferred, and aqueous ammonia of 2.5% by mass is particularly preferred. When it is aqueous ammonia of 5.0% by mass or less, ammonia containing ammonium ions is appropriate for fluoride ions and an increase in unnecessary costs can be avoided.

[0072] In this way, by diluting the obtained niobium-containing precipitate from which fluoride ions have been removed with pure water or the like, a precipitate slurry containing niobium from which fluoride ions have been removed can be obtained. The niobium concentration of the precipitate slurry containing niobium is determined by collecting a part of the slurry, drying it at 110 °C for 24 hours, then firing it at 1,000 °C for 4 hours to produce Nb2O5. The weight of the thus-produced Nb2O5 is measured, and the niobium concentration of the slurry can be calculated from that weight.

[0073] Then, by stirring a mixture obtained by mixing the precipitate slurry containing niobium from which fluoride ions have been removed with at least one selected from amines and ammonia, a niobic acid-containing liquid can be obtained.

[0074] At least one selected from amines and ammonia to be mixed with the precipitate slurry containing niobium is preferably an alkylamine, choline ([(CH3)3NCH2CH2OH] + ), choline hydroxide ([(CH3)3NCH2CH2OH] + OH - ), etc.

[0075] The alkylamine preferably has 1 to 4 alkyl groups. If it has 2 to 4 alkyl groups, all 2 to 4 alkyl groups may be the same, or they may be different. From the viewpoint of solubility, the alkyl groups of the alkylamine are preferably those with 1 to 6 carbon atoms, more preferably those with 4 or fewer carbon atoms, even more preferably those with 3 or fewer carbon atoms, and particularly preferably those with 2 or fewer carbon atoms.

[0076] Specific examples of alkylamines include methylamine, dimethylamine, trimethylamine, tetramethylammonium hydroxide, ethylamine, methylethylamine, diethylamine, triethylamine, methyldiethylamine, dimethylethylamine, tetraethylammonium hydroxide, n-propylamine, di-n-propylamine, tri-n-propylamine, iso-propylamine, diiso-propylamine, triiso-propylamine, n-butylamine, di-n-butylamine, tri-n-butylamine, iso-butylamine, diiso-butylamine, triiso-butylamine, and tert-butylamine, n-pentaamine, and n-hexaamine. In particular, from the viewpoint of solubility, methylamine, dimethylamine, trimethylamine, tetramethylammonium hydroxide, ethylamine, methylethylamine, diethylamine, triethylamine, methyldiethylamine, dimethylethylamine, and tetraethylammonium hydroxide are more preferred, methylamine, dimethylamine, trimethylamine, and tetramethylammonium hydroxide are even more preferred, and methylamine is particularly preferred.

[0077] Furthermore, the method for producing a tantalum acid-containing liquid, which is a metal acid compound used in the method for producing a metal acid compound-containing liquid of the present invention, will be described below.

[0078] A method for producing a tantalum acid-containing solution comprises a reaction step of adding hydrogen peroxide to an aqueous solution of tantalum fluoride to produce an aqueous solution of a tantalum compound; a reverse neutralization step of adding the aqueous solution of the tantalum compound to an alkaline aqueous solution to produce a tantalum-containing precipitate; and a step of mixing the produced tantalum-containing precipitate with an organic nitrogen compound.

[0079] First, an aqueous solution of tantalum fluoride can be prepared by reacting tantalum, tantalum oxide, or tantalum hydroxide with hydrofluoric acid (HF), such as an aqueous solution of hydrofluoric acid, to form tantalum fluoride (H2TaF7), which is then dissolved in water.

[0080] Here, it is preferable to adjust the acidic tantalum solution containing fluoride ions, for example, an aqueous solution of tantalum fluoride, by adding water (e.g., pure water) to a concentration of tantalum of 1 to 100 g / L in terms of Ta2O5. In this case, a tantalum concentration of 1 g / L or more in terms of Ta2O5 is preferable because it results in a tantalate compound hydrate that is easily soluble in water, and from the perspective of productivity, 10 g / L or more is more preferable, and 20 g / L or more is even more preferable. On the other hand, a tantalum concentration of 100 g / L or less in terms of Ta2O5 is also preferable because it results in a tantalate compound hydrate that is easily soluble in water, and to more reliably synthesize a tantalate compound hydrate that is easily soluble in water, 90 g / L or less is more preferable, 80 g / L or less is even more preferable, and 70 g / L or less is particularly preferable. The pH of the aqueous solution of tantalum fluoride is preferably 2 or less, and more preferably 1 or less, from the viewpoint of completely dissolving tantalum or tantalum oxide.

[0081] Next, in the reaction step to produce an aqueous tantalum compound aqueous solution by adding hydrogen peroxide to an aqueous tantalum fluoride solution, an aqueous tantalum compound aqueous solution is obtained by adding hydrogen peroxide solution to the aqueous tantalum fluoride aqueous solution and mixing it. It is presumed that at least a portion of the obtained aqueous tantalum compound aqueous solution forms a peroxo complex.

[0082] Here, the hydrogen peroxide concentration of the hydrogen peroxide solution added to the tantalum fluoride aqueous solution is preferably 0.5% to 35% by mass. Furthermore, it is preferable to add the hydrogen peroxide so that the molar ratio of hydrogen peroxide to tantalum (H2O2 / Ta) is between 0.6 and 1.5, and more preferably between 0.7 and 1.2, as hydrogen peroxide may decompose during mixing.

[0083] In the reverse neutralization step, where the obtained tantalum compound aqueous solution is added to an alkaline aqueous solution to produce a tantalum-containing precipitate, the tantalum compound aqueous solution is added to an alkaline aqueous solution, such as ammonia water, i.e., by reverse neutralization, a tantalum-containing precipitate slurry is obtained. Then, by removing fluoride ions from the obtained tantalum-containing precipitate slurry, a tantalum-containing precipitate from which fluoride ions have been removed is obtained.

[0084] The ammonia concentration of the ammonia solution used for reverse neutralization is preferably 10% to 30% by mass. A concentration of 10% by mass reduces the likelihood of undissolved tantalum, allowing for complete dissolution of tantalum or tantalic acid in water. On the other hand, a concentration of 30% by mass or less is preferable because it is close to a saturated aqueous solution of ammonia.

[0085] From this viewpoint, the ammonia concentration of the aqueous ammonia solution is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass or more. On the other hand, the ammonia concentration is preferably 30% by mass or less, more preferably 29% by mass or less, and even more preferably 28% by mass or less.

[0086] During the reverse neutralization step, the amount of tantalum fluoride aqueous solution added to the ammonia water is preferably such that the NH3 / Ta molar ratio is 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the viewpoint of generating amines and tantalic acid compounds that dissolve in dilute ammonia water, the amount of tantalum fluoride aqueous solution added to the ammonia water is preferably such that the NH3 / HF molar ratio is 3.0 or higher, more preferably 4.0 or higher, and even more preferably 5.0 or higher. On the other hand, from the viewpoint of cost reduction, the NH3 / HF molar ratio is preferably 100 or less, more preferably 50 or less, and even more preferably 40 or less.

[0087] In the reverse neutralization step, the time required for adding the tantalum fluoride aqueous solution to the ammonia water is preferably within 10 minutes, more preferably within 8 minutes, and even more preferably within 5 minutes. In other words, rather than gradually adding the tantalum fluoride aqueous solution over time, it is preferable to add it to the ammonia water in the shortest possible time, for example, by adding it all at once, to allow the neutralization reaction to occur. Furthermore, since the acidic tantalum fluoride aqueous solution is added to the alkaline ammonia water in the reverse neutralization step, the neutralization reaction can be carried out while maintaining a high pH. Note that the tantalum fluoride aqueous solution and the ammonia water can be used at room temperature.

[0088] Then, in the reverse neutralization step, fluoride ions are removed from the tantalum-containing precipitate slurry obtained by the reverse neutralization method, thereby obtaining a tantalum-containing precipitate from which fluoride ions have been removed. Since the tantalum-containing precipitate slurry obtained by the reverse neutralization method contains fluorine compounds such as ammonium fluoride as impurities, it is preferable to remove these.

[0089] The method for removing fluorine compounds is arbitrary, but methods such as reverse osmosis filtration using ammonia water or pure water, ultrafiltration, microfiltration using membranes, centrifugation, and other known methods can be employed. Furthermore, when removing fluoride ions from a precipitate slurry containing tantalum, temperature control is not particularly necessary, and the process can be carried out at room temperature.

[0090] Specifically, the tantalum-containing precipitate slurry obtained by the reverse neutralization method is decanted using a centrifuge, and the washing is repeated until the amount of free fluoride ions is 100 mg / L or less, thereby obtaining a tantalum-containing precipitate from which fluoride ions have been removed. In addition, by repeating this washing, the hydrogen peroxide added in the reaction step is also removed.

[0091] The cleaning solution used to remove fluoride ions is preferably ammonia water. Specifically, ammonia water containing 1% to 35% by mass is preferred. With such ammonia water, the ammonia and ammonium ions are suitable for fluorine, and unnecessary cost increases can be avoided.

[0092] After the reaction and reverse neutralization steps described above, the tantalum-containing precipitate from which the fluoride ions have been removed is diluted with pure water or the like to obtain a tantalum-containing precipitate slurry from which the fluoride ions have been removed. The tantalum concentration of the tantalum-containing precipitate slurry can be determined by taking a sample of the slurry, drying it at 110°C for 24 hours, and then calcining it at 1,000°C for 4 hours to produce Ta2O5. The weight of the Ta2O5 produced in this way can be measured, and the tantalum concentration of the tantalum-containing precipitate slurry can be calculated from this weight.

[0093] Then, a tantalum-containing solution is obtained by mixing the tantalum-containing precipitate slurry from which fluoride ions have been removed, an organic nitrogen compound, and pure water, and holding the mixture at 5°C to 90°C for 0.1 to 48 hours while stirring.

[0094] The organic nitrogen compound to be mixed with the tantalum-containing precipitate slurry is preferably an aliphatic amine, aromatic amine, amino alcohol, amino acid, polyamine, quaternary ammonium, guanidine compound, or azole compound, as described above, and is particularly preferably an aliphatic amine and / or a quaternary ammonium compound.

[0095] From the viewpoint of solubility, it is preferable to mix the aliphatic amine in the tantalum-containing precipitate slurry so that the aliphatic amine concentration is 40% by mass or less, and more preferably 20% by mass or less. Similarly, from the same viewpoint, it is preferable to mix the aliphatic amine in the tantalum-containing precipitate slurry so that the aliphatic amine concentration is 0.1% by mass or more, more preferably 1% by mass or more, and may also be 5% by mass or more, or 10% by mass or more. The aliphatic amine is more preferably methylamine or dimethylamine.

[0096] Furthermore, from the viewpoint of solubility, it is preferable to mix the quaternary ammonium compound so that the concentration of the quaternary ammonium compound in the tantalum-containing precipitate slurry is 40% by mass or less, and more preferably 20% by mass or less. Similarly, from the same viewpoint, it is preferable to mix the quaternary ammonium compound so that the concentration of the quaternary ammonium compound in the tantalum-containing precipitate slurry is 0.1% by mass or more, more preferably 1% by mass or more, and may also be 5% by mass or more, or 10% by mass or more. The quaternary ammonium compound is more preferably tetramethylammonium hydroxide (TMAH) or tetraethylammonium hydroxide (TEAH).

[0097] Furthermore, the method for producing a titanic acid-containing liquid, which is a metal acid compound used in the method for producing a metal acid compound-containing liquid of the present invention, will be described below.

[0098] A method for producing a titanic acid-containing solution comprises a neutralization step of mixing a titanium salt solution with an amine aqueous solution to obtain a neutralization reaction solution, a washing step of washing the titanium-containing precipitate formed in the neutralization reaction solution, and a dissolution step of mixing the washed titanium-containing precipitate with a quaternary ammonium salt and water to obtain a titanic acid-containing solution.

[0099] A titanium salt solution can be any solution in which titanium is dissolved. Examples include aqueous solutions of titanyl sulfate, titanium chloride, and titanium fluoride. Aqueous titanium chloride is produced by dissolving titanium chloride (TiCl5) in a small amount of methanol and then adding water. Furthermore, an aqueous solution of titanyl sulfate is produced by dissolving titanyl sulfate in hot water. The titanium content in the aqueous solution of titanyl sulfate should be prepared to be 8-15% by mass in terms of TiO2.

[0100] In the neutralization step, a neutralization reaction solution is obtained by mixing the above-mentioned titanium salt solution with an amine aqueous solution and allowing it to react. In this neutralization step, it is preferable to perform reverse neutralization, in which a titanium salt solution, such as an aqueous solution of titanyl sulfate, is added to the amine aqueous solution and reacted. It is presumed that by performing reverse neutralization in this way, the structure of titanium or titanic acid becomes a structure that is easily soluble in water.

[0101] The amine used in the amine aqueous solution in the neutralization step is preferably an alkylamine. The alkylamine preferably has 1 to 3 alkyl groups. If it has 2 to 3 alkyl groups, all three alkyl groups may be the same or may be different. From the viewpoint of solubility, the alkyl group of the alkylamine is preferably one with 1 to 6 carbon atoms, more preferably one with 4 or fewer carbon atoms, even more preferably one with 3 or fewer carbon atoms, and particularly preferably one with 2 or fewer carbon atoms.

[0102] Specific examples of alkylamines include methylamine, dimethylamine, trimethylamine, ethylamine, methylethylamine, diethylamine, triethylamine, methyldiethylamine, dimethylethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, iso-propylamine, diiso-propylamine, triiso-propylamine, n-butylamine, di-n-butylamine, tri-n-butylamine, iso-butylamine, diiso-butylamine, triiso-butylamine, and tert-butylamine, n-pentaamine, and n-hexaamine. In particular, from the viewpoint of solubility, methylamine, dimethylamine, trimethylamine, ethylamine, methylethylamine, diethylamine, triethylamine, methyldiethylamine, and dimethylethylamine are preferred, and methylamine, dimethylamine, and trimethylamine are more preferred.

[0103] Furthermore, in the neutralization step, from the viewpoint of improving dispersibility, it is preferable to add the titanium salt solution to an amine aqueous solution containing an amount equal to or greater than the amount of sulfuric acid contained in the titanium salt solution, i.e., 1 or more amines, more preferably to add it to an amine aqueous solution containing 1.2 or more amines, and even more preferably to add it to an amine aqueous solution containing 1.4 or more amines. On the other hand, from the viewpoint of reducing the amount of waste liquid, it is preferable to add the titanium salt solution to an amine aqueous solution containing an amount of sulfuric acid contained in the titanium salt solution containing 2 or less amines, more preferably to add it to an amine aqueous solution containing 1.8 or less amines, and even more preferably to add it to an amine aqueous solution containing 1.6 or less amines.

[0104] Furthermore, in the neutralization step, when adding a titanium salt solution, such as an aqueous solution of titanyl sulfate, to the aqueous amine solution, it is preferable to allow the neutralization reaction to occur within 1 minute. That is, rather than adding the titanium salt solution gradually over time, it is preferable to add it all at once, for example, within 1 minute, to allow the neutralization reaction to occur. In this case, the addition time of the titanium salt solution is preferably within 1 minute, more preferably within 30 seconds, and even more preferably within 10 seconds.

[0105] Next, the cleaning method in the washing process can be, for example, a membrane filtration method such as reverse osmosis filtration, ultrafiltration, or microfiltration using ammonia water or pure water, as well as centrifugal separation or other known methods. The washing process can be carried out at room temperature, and no special temperature adjustment is necessary.

[0106] In the neutralization reaction solution obtained in the neutralization process described above, particularly the titanium-containing precipitate, unwanted components other than titanium or titanic acid hydrates or ions and amines, such as sulfate compounds including ammonium sulfate, are present in the water as impurities. Therefore, it is preferable to wash and remove these unwanted components.

[0107] Then, in the dissolution process, the titanium-containing precipitate obtained by washing in the washing process, for example, the titanium-containing precipitate obtained by removing sulfuric acid, is mixed with a dispersion medium such as water, and a quaternary ammonium salt is added, and the mixture is stirred as needed to obtain a titanic acid-containing liquid.

[0108] Here, examples of quaternary ammonium salts include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltripropylammonium hydroxide, methyltributylammonium hydroxide, tetrapentylammonium hydroxide, tetrahexylammonium hydroxide, ethyltrimethylammonium hydroxide, dimethyldiethylammonium hydroxide, benzyltrimethylammonium hydroxide, hexadecyltrimethylammonium hydroxide, or (2-hydroxyethyl)trimethylammonium hydroxide. Note that if primary to tertiary amines or their salts are added instead of the above-mentioned quaternary ammonium salts, aqueous solution cannot be formed.

[0109] As mentioned above, a larger amount of quaternary ammonium salt can increase the solubility of titanium or titanic acid in water. Therefore, in the dissolution step, it is preferable to mix a quaternary ammonium salt containing 0.44 moles or more of quaternary ammonium per mole of titanium contained in the titanium-containing precipitate after washing. On the other hand, too much quaternary ammonium can cause problems such as impeding film formation or inhibiting catalytic activity. Therefore, in the dissolution step, it is preferable to mix a quaternary ammonium salt containing 1.0 mole or less of quaternary ammonium per mole of titanium contained in the titanium-containing precipitate after washing.

[0110] Furthermore, the method for producing a molybdic acid-containing solution, which is a metal acid compound used in the method for producing a metal acid compound-containing solution of the present invention, will be described below.

[0111] A method for producing a molybdic acid-containing solution is characterized by comprising the steps of: adding an acidic molybdenum aqueous solution containing 1 to 100 g / L of molybdenum (in terms of MoO3) to a 10 to 30% by mass ammonia aqueous solution to produce a molybdenum-containing precipitate; and adding an organic nitrogen compound to the molybdenum-containing precipitate slurry, which is a slurry of the molybdenum-containing precipitate, to produce a molybdic acid-containing solution.

[0112] First, in the step of adding an acidic molybdenum aqueous solution containing 1 to 100 g / L of molybdenum (in terms of MoO3) to a 10 to 30% by mass ammonia aqueous solution to produce a molybdenum-containing precipitate, the acidic molybdenum aqueous solution refers to an aqueous solution of molybdenum sulfate obtained by solvent extraction of a solution in which molybdenum has dissolved in an acidic aqueous solution containing sulfuric acid. Unless otherwise specified, the molybdenum referred to in this specification includes molybdenum oxide.

[0113] Here, it is preferable to adjust the molybdenum sulfate aqueous solution by adding water (e.g., pure water) so that it contains 1 to 100 g / L of molybdenum in terms of MoO3. In this case, a molybdenum concentration of 1 g / L or more in terms of MoO3 is preferable because it results in a molybdate compound hydrate that is easily soluble in water, and from the perspective of productivity, 10 g / L or more is more preferable, and 20 g / L or more is even more preferable. On the other hand, a molybdenum concentration of 100 g / L or less in terms of MoO3 is also preferable because it results in a molybdate compound hydrate that is easily soluble in water, and to more reliably synthesize a molybdate compound hydrate that is easily soluble in water, it is more preferable to have a concentration of 90 g / L or less, even more preferable to have a concentration of 80 g / L or less, and particularly preferable to have a concentration of 70 g / L or less. The pH of the molybdenum sulfate aqueous solution is preferably 2 or less, and more preferably 1 or less, from the viewpoint of completely dissolving molybdenum or molybdenum oxide.

[0114] When adding an aqueous solution of molybdenum sulfate to an aqueous solution of ammonia, in the so-called reverse neutralization method, it is preferable to add the aqueous solution of molybdenum sulfate to an aqueous solution of ammonia containing 10% to 30% by mass, i.e., to obtain a slurry of molybdate compound hydrate, or so-called molybdenum-containing precipitate, by the reverse neutralization method.

[0115] The ammonia concentration of the aqueous ammonia solution used for reverse neutralization is preferably 10% to 30% by mass. When the ammonia concentration is 10% by mass, molybdenum is less likely to remain undissolved, allowing molybdenum or molybdenum oxide to be completely dissolved in water. On the other hand, an ammonia concentration of 30% by mass or less is preferable because it is close to a saturated aqueous solution of ammonia.

[0116] From this viewpoint, the ammonia concentration of the aqueous ammonia solution is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass. On the other hand, the ammonia concentration is preferably 30% by mass or less, more preferably 29% by mass or less, and even more preferably 28% by mass or less.

[0117] During reverse neutralization, the amount of molybdenum sulfate aqueous solution added to the ammonia water is preferably such that the molar ratio of NH3 / MoO3 is 0.1 to 300, and more preferably 5 to 200. Furthermore, from the viewpoint of generating amines and molybdate compounds that dissolve in dilute ammonia water, the molybdenum sulfate aqueous solution added to the ammonia water should be NH3 / SO4 2- The molar ratio of NH3 / SO4 is preferably 3.0 or higher, more preferably 10.0 or higher, and even more preferably 20.0 or higher. On the other hand, from the viewpoint of cost reduction, 2- The molar ratio is preferably 200 or less, more preferably 150 or less, and even more preferably 100 or less.

[0118] In reverse neutralization, the time required for adding the molybdenum sulfate aqueous solution to the ammonia water is preferably within 1 minute, more preferably within 30 seconds, and even more preferably within 10 seconds. In other words, rather than gradually adding the molybdenum sulfate aqueous solution over time, it is preferable to add it to the ammonia water in the shortest possible time, for example, by adding it all at once, to allow the neutralization reaction to occur. Furthermore, in reverse neutralization, since the acidic molybdenum sulfate aqueous solution is added to the alkaline ammonia water, the neutralization reaction can be carried out while maintaining a high pH. The molybdenum sulfate aqueous solution and the ammonia water can be used at room temperature.

[0119] Then, sulfur is removed from the molybdenum-containing precipitate slurry obtained by the reverse neutralization method to produce a molybdenum-containing precipitate from which sulfur has been removed. The molybdenum-containing precipitate slurry obtained by the reverse neutralization method contains sulfurous sulfate ions and hydrogen sulfate ions that remain unreacted with molybdenum or molybdenum oxide as impurities, so it is preferable to remove these.

[0120] The method for removing sulfur is arbitrary, but methods such as reverse osmosis filtration using ammonia water or pure water, ultrafiltration, microfiltration using membranes, centrifugal separation, and other known methods can be employed. Furthermore, when removing sulfur from the molybdenum-containing precipitate slurry, temperature control is not particularly necessary, and the process may be carried out at room temperature.

[0121] Specifically, the slurry of molybdenum-containing precipitate obtained by the reverse neutralization method is decanted using a centrifuge, and the washing is repeated until the conductivity of the molybdenum-containing precipitate slurry is 500 μS / cm or less, thereby obtaining a molybdenum-containing precipitate from which sulfur has been removed. The conductivity was measured by adjusting the liquid temperature of the molybdenum-containing precipitate slurry to 25°C, immersing the measuring unit of a conductivity meter (ASCON2, manufactured by AS ONE Corporation) in the supernatant of the precipitate slurry, and reading the value after the conductivity value stabilized.

[0122] The cleaning solution used to remove sulfur is preferably ammonia water. Specifically, ammonia water at 5.0% by mass or less is preferred, 4.0% by mass or less is more preferred, 3.0% by mass or less is even more preferred, and 2.5% by mass is particularly preferred. Using ammonia water at 5.0% by mass or less ensures that the ammonia and ammonium ions are appropriate for the sulfur content and can avoid unnecessary cost increases.

[0123] Next, in the step of adding an organic nitrogen compound to the molybdenum-containing precipitate slurry, which is made by turning the molybdenum-containing precipitate into a slurry, to produce a molybdic acid-containing solution, the molybdenum-containing precipitate slurry is made by diluting the molybdenum-containing precipitate from which sulfur has been removed, as described above, with pure water or the like to make it into a slurry. The molybdenum concentration of the molybdenum-containing precipitate slurry from which sulfur has been removed can be determined by taking a portion of the slurry, drying it at 110°C for 24 hours, and then calcining it at 1,000°C for 4 hours to produce MoO3. The weight of the MoO3 thus produced can be measured, and the molybdenum concentration of the slurry can be calculated from that weight.

[0124] Then, by mixing an organic nitrogen compound with the molybdenum-containing precipitate slurry from which the sulfur has been removed, a molybdic acid-containing solution is obtained.

[0125] Specifically, the obtained molybdenum-containing precipitate slurry is added to an organic nitrogen compound and mixed with pure water, so that the final molybdenum concentration of the mixture is 0.1 to 40% by mass in terms of MoO3. The mixture is then stirred and the liquid temperature is maintained at room temperature (25°C) for 1 hour to obtain a colorless, transparent molybdic acid-containing liquid.

[0126] The organic nitrogen compound mixed with the molybdenum-containing precipitate slurry is preferably an aliphatic amine and / or a quaternary ammonium compound.

[0127] Here, from the viewpoint of solubility, it is preferable to mix the aliphatic amine so that the concentration of the aliphatic amine in the molybdenum-containing precipitate slurry is 40% by mass or less. Similarly, from the same viewpoint, it is preferable to mix the aliphatic amine so that the concentration of the aliphatic amine in the molybdenum-containing precipitate slurry is 0.1% by mass or more, and more preferably 20% by mass or more. The aliphatic amine is more preferably methylamine or dimethylamine, and particularly preferably methylamine.

[0128] On the other hand, from the viewpoint of solubility, it is preferable to mix the quaternary ammonium in the molybdenum-containing precipitate slurry so that the concentration of quaternary ammonium in the slurry is 40% by mass or less. Similarly, from the same viewpoint, it is preferable to mix the quaternary ammonium in the molybdenum-containing precipitate slurry so that the concentration is 0.1% by mass or more, and more preferably 20% by mass or more. It is even more preferable that the quaternary ammonium is tetramethylammonium hydroxide (TMAH).

[0129] Furthermore, the organic nitrogen compound mixed with the molybdenum-containing precipitate slurry may be a mixture of two or more aliphatic amines or quaternary ammonium compounds, rather than just one of either. For example, a mixture of two or more organic nitrogen compounds such as methylamine and tetramethylammonium hydroxide (TMAH), dimethylamine and tetramethylammonium hydroxide (TMAH), or methylamine and dimethylamine, or a mixture of three or more organic nitrogen compounds such as methylamine, dimethylamine, and tetramethylammonium hydroxide (TMAH), may be used, and the mixture may be appropriately modified according to the application.

[0130] Furthermore, the method for producing a tungstic acid-containing liquid, which is a metal acid compound used in the method for producing a metal acid compound-containing liquid of the present invention, will be described below.

[0131] A method for producing a tungstic acid-containing liquid is characterized by comprising the steps of: adding an acidic tungsten aqueous solution containing 1 to 100 g / L of tungsten (calculated as WO3) to a 10 to 30% by mass aqueous ammonia solution to produce a tungsten-containing precipitate; and adding an organic nitrogen compound to the tungsten-containing precipitate slurry, which is a slurry of the tungsten-containing precipitate, to produce a tungstic acid-containing liquid.

[0132] First, in the step of adding an acidic tungsten aqueous solution containing 1 to 100 g / L of tungsten (calculated as WO3) to a 10 to 30% by mass ammonia aqueous solution to produce a tungsten-containing precipitate, the acidic tungsten aqueous solution refers to an aqueous tungsten sulfate solution obtained by solvent extraction of the solution in which tungsten has dissolved in an acidic aqueous solution containing sulfuric acid. Unless otherwise specified, the tungsten referred to in this specification includes tungsten oxides.

[0133] Here, it is preferable to adjust the tungsten sulfate aqueous solution by adding water (e.g., pure water) so that it contains 1 to 100 g / L of tungsten in terms of WO3. In this case, a tungsten concentration of 1 g / L or more in terms of WO3 is preferable because it results in a tungstic acid compound hydrate that is easily soluble in water, and from the perspective of productivity, 10 g / L or more is more preferable, and 20 g / L or more is even more preferable. On the other hand, a tungsten concentration of 100 g / L or less in terms of WO3 is also preferable because it results in a tungstic acid compound hydrate that is easily soluble in water, and to more reliably synthesize a tungstic acid compound hydrate that is easily soluble in water, it is more preferable to have a concentration of 90 g / L or less, even more preferable to have a concentration of 80 g / L or less, and particularly preferable to have a concentration of 70 g / L or less. The pH of the tungsten sulfate aqueous solution is preferably 2 or less, and more preferably 1 or less, from the viewpoint of completely dissolving tungsten or tungsten oxide.

[0134] When adding an aqueous solution of tungsten sulfate to an aqueous solution of ammonia, in the so-called reverse neutralization method, it is preferable to add the aqueous solution of tungsten sulfate to an aqueous solution of 10% to 30% by mass of ammonia, that is, to obtain a slurry of tungstic acid compound hydrate, or so-called tungsten-containing precipitate, by the reverse neutralization method.

[0135] The ammonia concentration of the aqueous ammonia solution used for reverse neutralization is preferably 10% to 30% by mass. When the ammonia concentration is 10% by mass, tungsten is less likely to remain undissolved, allowing tungsten or tungsten oxide to be completely dissolved in water. On the other hand, an ammonia concentration of 30% by mass or less is preferable because it is close to a saturated aqueous solution of ammonia.

[0136] From this viewpoint, the ammonia concentration of the aqueous ammonia solution is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass. On the other hand, the ammonia concentration is preferably 30% by mass or less, more preferably 29% by mass or less, and even more preferably 28% by mass or less.

[0137] During reverse neutralization, the amount of tungsten sulfate aqueous solution added to the ammonia water is preferably such that the molar ratio of NH3 / WO3 is 0.1 to 300, and more preferably 5 to 200. Furthermore, from the viewpoint of generating amines and tungstic acid compounds that dissolve in dilute ammonia water, the tungsten sulfate aqueous solution added to the ammonia water should be NH3 / SO4 2- The molar ratio of NH3 / SO4 is preferably 3.0 or higher, more preferably 10.0 or higher, and even more preferably 20.0 or higher. On the other hand, from the viewpoint of cost reduction, 2- The molar ratio is preferably 200 or less, more preferably 150 or less, and even more preferably 100 or less.

[0138] In reverse neutralization, the time required for adding the tungsten sulfate aqueous solution to the ammonia water is preferably within 1 minute, more preferably within 30 seconds, and even more preferably within 10 seconds. In other words, rather than gradually adding the tungsten sulfate aqueous solution over time, it is preferable to add it to the ammonia water in the shortest possible time, for example, by adding it all at once, to allow the neutralization reaction to occur. Furthermore, in reverse neutralization, since the acidic tungsten sulfate aqueous solution is added to the alkaline ammonia water, the neutralization reaction can be carried out while maintaining a high pH. The tungsten sulfate aqueous solution and ammonia water can be used at room temperature.

[0139] Then, sulfur is removed from the tungsten-containing precipitate slurry obtained by the reverse neutralization method to produce a tungsten-containing precipitate from which the sulfur has been removed. The tungsten-containing precipitate slurry obtained by the reverse neutralization method contains sulfurous sulfate ions and hydrogen sulfate ions that remain unreacted with tungsten or tungsten oxide as impurities, so it is preferable to remove these.

[0140] The method for removing sulfur is arbitrary, but methods such as reverse osmosis filtration using ammonia water or pure water, ultrafiltration, microfiltration using membranes, centrifugation, or other known methods can be employed. When removing sulfur from the tungsten-containing precipitate slurry, temperature control is not particularly necessary, and the process may be carried out at room temperature.

[0141] Specifically, the tungsten-containing precipitate slurry obtained by the reverse neutralization method is decanted using a centrifuge, and the washing is repeated until the conductivity of the tungsten-containing precipitate slurry is 500 μS / cm or less, thereby obtaining a tungsten-containing precipitate from which sulfur has been removed. The conductivity was measured by adjusting the liquid temperature of the tungsten-containing precipitate slurry to 25°C, immersing the measuring unit of a conductivity meter (ASCON2, manufactured by AS ONE Corporation) in the supernatant of the precipitate slurry, and reading the value after the conductivity value stabilized.

[0142] The cleaning solution used to remove sulfur is preferably ammonia water. Specifically, ammonia water at 5.0% by mass or less is preferred, 4.0% by mass or less is more preferred, 3.0% by mass or less is even more preferred, and 2.5% by mass is particularly preferred. Using ammonia water at 5.0% by mass or less ensures that the ammonia and ammonium ions are appropriate for the sulfur content and can avoid unnecessary cost increases.

[0143] Next, in the step of adding an organic nitrogen compound to the tungsten-containing precipitate slurry, which is made by turning the tungsten-containing precipitate into a slurry, in order to produce a tungstic acid-containing liquid, the tungsten-containing precipitate slurry is made by diluting the tungsten-containing precipitate from which the sulfur has been removed, as described above, with pure water or the like to make it into a slurry. The tungsten concentration of the tungsten-containing precipitate slurry from which the sulfur has been removed can be determined by taking a portion of the slurry, drying it at 110°C for 24 hours, and then calcining it at 1,000°C for 4 hours to produce WO3. The weight of the WO3 thus produced can be measured, and the tungsten concentration of the slurry can be calculated from that weight.

[0144] Then, by mixing an organic nitrogen compound with the tungsten-containing precipitate slurry from which the sulfur has been removed, a tungstic acid-containing solution is obtained.

[0145] Specifically, the obtained tungsten-containing precipitate slurry is added to an organic nitrogen compound and mixed with pure water, so that the final tungsten concentration of the mixture is 0.1 to 40% by mass in terms of WO3. The mixture is then stirred and the liquid temperature is maintained at room temperature (25°C) for 1 hour to obtain a colorless, transparent tungstic acid-containing liquid.

[0146] The organic nitrogen compound mixed with the tungsten-containing precipitate slurry is preferably an aliphatic amine and / or a quaternary ammonium compound.

[0147] Here, from the viewpoint of solubility, it is preferable to mix the aliphatic amine so that the concentration of the aliphatic amine in the tungsten-containing precipitate slurry is 40% by mass or less. Similarly, from the same viewpoint, it is preferable to mix the aliphatic amine so that the concentration of the aliphatic amine in the tungsten-containing precipitate slurry is 0.1% by mass or more, and more preferably 20% by mass or more. The aliphatic amine is more preferably methylamine or dimethylamine.

[0148] On the other hand, from the viewpoint of solubility, it is preferable to mix the quaternary ammonium in the tungsten-containing precipitate slurry so that the concentration of quaternary ammonium in the slurry is 40% by mass or less. Similarly, from the same viewpoint, it is preferable to mix the quaternary ammonium in the tungsten-containing precipitate slurry so that the concentration is 0.1% by mass or more, and more preferably 20% by mass or more. It is more preferable that the quaternary ammonium is tetramethylammonium hydroxide (TMAH).

[0149] Furthermore, the organic nitrogen compound mixed with the tungsten-containing precipitate slurry may be a mixture of two or more aliphatic amines or quaternary ammonium compounds, rather than just one of either. For example, a mixture of two or more organic nitrogen compounds such as methylamine and tetramethylammonium hydroxide (TMAH), dimethylamine and tetramethylammonium hydroxide (TMAH), or methylamine and dimethylamine, or a mixture of three or more organic nitrogen compounds such as methylamine, dimethylamine, and tetramethylammonium hydroxide (TMAH), may be used, and the mixture may be appropriately modified according to the application.

[0150] Furthermore, the method for producing a zirconium acid-containing liquid, which is a metal acid compound used in the method for producing a metal acid compound-containing liquid of the present invention, will be described below.

[0151] A method for producing a zirconium acid-containing solution comprises the steps of: adding hydrogen peroxide to an acidic zirconium aqueous solution containing 1 to 100 g / L of zirconium in terms of ZrO2; adding the resulting acidic zirconium aqueous solution with added hydrogen peroxide to a 10 to 30% by mass ammonia aqueous solution to produce a zirconium-containing precipitate; and adding an organic nitrogen compound to the zirconium-containing precipitate slurry, which is a slurry of the zirconium-containing precipitate, to produce a zirconium acid-containing solution.

[0152] First, hydrogen peroxide is added to an acidic zirconium aqueous solution containing 1 to 100 g / L of zirconium (based on ZrO2), and the resulting acidic zirconium aqueous solution with added hydrogen peroxide is added to a 10 to 30% by mass ammonia aqueous solution to produce a zirconium-containing precipitate. In this process, the acidic zirconium aqueous solution refers to an aqueous solution of zirconium sulfate obtained by solvent extraction of a solution in which zirconium is dissolved in an acidic aqueous solution containing sulfuric acid, or an aqueous solution of zirconium oxychloride (octahydrate), etc. In this specification, zirconium refers to zirconium oxide unless otherwise specified.

[0153] Here, it is preferable to adjust the zirconium sulfate aqueous solution by adding water (e.g., pure water) so that it contains zirconium in terms of 1 to 100 g / L in terms of ZrO2. In this case, a zirconium concentration of 1 g / L or more in terms of ZrO2 is preferable because it results in a water-soluble zirconium acid compound hydrate, and from the perspective of productivity, 10 g / L or more is more preferable, and 20 g / L or more is even more preferable. On the other hand, a zirconium concentration of 100 g / L or less in terms of ZrO2 is also preferable because it results in a water-soluble zirconium acid compound hydrate, and to more reliably synthesize a water-soluble zirconium acid compound hydrate, it is more preferable to have a concentration of 90 g / L or less, even more preferable to have a concentration of 80 g / L or less, and particularly preferable to have a concentration of 70 g / L or less. The pH of the zirconium sulfate aqueous solution is preferably 2 or less, and more preferably 1 or less, from the viewpoint of completely dissolving zirconium or zirconium oxide.

[0154] Next, by adding hydrogen peroxide to the zirconium sulfate aqueous solution, the zirconium-containing anionic species complexes, forming a peroxo complex with excellent solubility. Here, the amount of hydrogen peroxide added to the zirconium sulfate aqueous solution is preferably such that the H2O2 / ZrO2 molar ratio is 1.0 or higher, and more preferably 2.5 or higher, in terms of excellent solubility. On the other hand, a H2O2 / ZrO2 molar ratio of 5.0 or lower is preferable in terms of excellent safety.

[0155] In this manner, when adding the resulting hydrogen peroxide-added zirconium sulfate aqueous solution to an ammonia aqueous solution, in the so-called reverse neutralization method, it is preferable to add the hydrogen peroxide-added zirconium sulfate aqueous solution to a 10% to 30% by mass ammonia aqueous solution to obtain a slurry of zirconium acid compound hydrate, or so-called zirconium-containing precipitate slurry.

[0156] The ammonia concentration of the aqueous ammonia solution used for reverse neutralization is preferably 10% to 30% by mass. A concentration of 10% by mass reduces the likelihood of undissolved zirconium, allowing for complete dissolution of zirconium or zirconium oxide in water. On the other hand, a concentration of 30% by mass or less is preferable because it is close to a saturated aqueous solution of ammonia.

[0157] From this viewpoint, the ammonia concentration of the aqueous ammonia solution is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass. On the other hand, the ammonia concentration is preferably 30% by mass or less, more preferably 29% by mass or less, and even more preferably 28% by mass or less.

[0158] During reverse neutralization, the amount of zirconium sulfate aqueous solution to which hydrogen peroxide is added to ammonia water is preferably such that the molar ratio of NH3 / ZrO2 is 70 to 300, more preferably 100 to 300, and even more preferably 140 to 300, in terms of excellent solubility. Furthermore, the zirconium sulfate aqueous solution to which hydrogen peroxide is added to ammonia water is preferably such that amines and zirconium acid compounds that dissolve in dilute ammonia water are formed. 2- The molar ratio of NH3 / SO4 is preferably 3.0 or higher, more preferably 10.0 or higher, and even more preferably 20.0 or higher. On the other hand, from the viewpoint of cost reduction, 2- The molar ratio is preferably 200 or less, more preferably 150 or less, and even more preferably 100 or less.

[0159] In reverse neutralization, the time required to add the zirconium sulfate aqueous solution with added hydrogen peroxide to the ammonia water is preferably within 1 minute, more preferably within 30 seconds, and even more preferably within 10 seconds. In other words, rather than gradually adding the zirconium sulfate aqueous solution with added hydrogen peroxide over time, it is preferable to add it to the ammonia water in the shortest possible time, for example, by adding it all at once, to allow the neutralization reaction to occur. Furthermore, in reverse neutralization, since the acidic zirconium sulfate aqueous solution with added hydrogen peroxide is added to the alkaline ammonia water, the neutralization reaction can be carried out while maintaining a high pH. Note that the zirconium sulfate aqueous solution with added hydrogen peroxide and the ammonia water can be used at room temperature.

[0160] Then, sulfur is removed from the zirconium-containing precipitate slurry obtained by the reverse neutralization method to produce a zirconium-containing precipitate from which the sulfur has been removed. The zirconium-containing precipitate slurry obtained by the reverse neutralization method contains sulfurous sulfate ions and hydrogen sulfate ions that remain unreacted with zirconium or zirconium oxide as impurities, so it is preferable to remove these. Note that the added hydrogen peroxide is not removed and remains along with the zirconium-containing precipitate.

[0161] The method for removing sulfur is arbitrary, but methods such as reverse osmosis filtration using ammonia water or pure water, ultrafiltration, microfiltration using membranes, centrifugal separation, and other known methods can be employed. Furthermore, when removing sulfur from the zirconium-containing precipitate slurry, temperature control is not particularly necessary, and the process may be carried out at room temperature.

[0162] Specifically, the zirconium-containing precipitate slurry obtained by the reverse neutralization method is decanted using a centrifuge, and the washing is repeated until the conductivity of the zirconium-containing precipitate slurry is 500 μS / cm or less, thereby obtaining a zirconium-containing precipitate from which sulfur has been removed. The conductivity was measured by adjusting the liquid temperature of the zirconium-containing precipitate slurry to 25°C, immersing the measuring unit of a conductivity meter (ASCON2, manufactured by AS ONE Corporation) in the supernatant of the precipitate slurry, and reading the value after the conductivity value stabilized.

[0163] The cleaning solution used to remove sulfur is preferably ammonia water. Specifically, ammonia water at 5.0% by mass or less is preferred, 4.0% by mass or less is more preferred, 3.0% by mass or less is even more preferred, and 2.5% by mass is particularly preferred. Using ammonia water at 5.0% by mass or less ensures that the ammonia and ammonium ions are appropriate for the sulfur content and can avoid unnecessary cost increases.

[0164] Next, in the step of adding an organic nitrogen compound to the zirconium-containing precipitate slurry, which is made by turning the zirconium-containing precipitate into a slurry, in order to produce a zirconium acid-containing solution, the zirconium-containing precipitate slurry is made by diluting the zirconium-containing precipitate from which the sulfur has been removed, as described above, with pure water or the like to make it into a slurry. The zirconium concentration of the zirconium-containing precipitate slurry from which the sulfur has been removed can be determined by taking a portion of the slurry, drying it at 110°C for 24 hours, and then calcining it at 1,000°C for 4 hours to produce ZrO2. The weight of the ZrO2 thus produced can be measured, and the zirconium concentration of the slurry can be calculated from that weight.

[0165] Then, by mixing an organic nitrogen compound with the zirconium-containing precipitate slurry from which the sulfur has been removed, a zirconium acid-containing solution is obtained.

[0166] Specifically, the obtained zirconium-containing precipitate slurry is added to an organic nitrogen compound and mixed with pure water, so that the final zirconium concentration of the mixture is 0.1 to 10% by mass in terms of ZrO2. The mixture is then stirred and the liquid temperature is maintained at room temperature (25°C) for 1 hour to obtain a yellow or colorless, transparent zirconium acid-containing solution.

[0167] The organic nitrogen compound mixed with the zirconium-containing precipitate slurry is preferably a quaternary ammonium compound.

[0168] Here, from the viewpoint of solubility, it is preferable to mix the quaternary ammonium in the zirconium-containing precipitate slurry so that the concentration of quaternary ammonium in the slurry is 40% by mass or less. Also, from the same viewpoint, it is preferable to mix the quaternary ammonium in the zirconium-containing precipitate slurry so that the concentration is 0.1% by mass or more, and more preferably 20% by mass or more.

[0169] Furthermore, the quaternary ammonium is more preferably tetramethylammonium hydroxide (TMAH). The amount of tetramethylammonium hydroxide (TMAH) added to the zirconium-containing precipitate slurry is preferably such that the TMAH / ZrO2 molar ratio is 1.5 or higher for excellent solubility and stability, and more preferably 2.0 or higher for even better stability. On the other hand, a TMAH / ZrO2 molar ratio of 5.0 or lower is preferable for excellent safety. Note that if the TMAH / ZrO2 molar ratio is less than 1.0, the zirconium-containing precipitate slurry will not dissolve, and if it is between 1.0 and 1.4, the zirconium-containing precipitate slurry will dissolve but will gel.

[0170] Furthermore, the organic nitrogen compound mixed with the zirconium-containing precipitate slurry may be a mixture of two or more quaternary ammonium compounds, rather than just one. For example, a mixture of two or more organic nitrogen compounds such as tetramethylammonium hydroxide (TMAH) and methylamine, or tetramethylammonium hydroxide (TMAH) and dimethylamine, or a mixture of three or more organic nitrogen compounds such as tetramethylammonium hydroxide (TMAH), methylamine, and dimethylamine may be used, and the mixture may be appropriately modified depending on the application.

[0171] Furthermore, the method for producing a hafnium acid-containing liquid, which is a metal acid compound used in the method for producing a metal acid compound-containing liquid of the present invention, will be described below.

[0172] First, hafnium or hafnium oxide is reacted with hydrofluoric acid (HF), such as an aqueous solution of hydrofluoric acid, to form hafnium fluoride (H2HfF6). Dissolving this in water yields an acidic metal aqueous solution of hafnium fluoride.

[0173] Here, it is preferable to adjust the hafnium fluoride aqueous solution by adding water (e.g., pure water) so that it contains hafnium at a concentration of 1 to 100 g / L in terms of HfO2. In this case, a hafnium concentration of 1 g / L or more in terms of HfO2 is preferable because it results in a hafnium acid compound hydrate that is easily soluble in water, and from the perspective of productivity, 10 g / L or more is more preferable, and 20 g / L or more is even more preferable. On the other hand, a hafnium concentration of 100 g / L or less in terms of HfO2 is also preferable because it results in a hafnium acid compound hydrate that is easily soluble in water, and to more reliably synthesize a hafnium acid compound hydrate that is easily soluble in water, it is more preferable to have a concentration of 90 g / L or less, even more preferable to have a concentration of 80 g / L or less, and particularly preferable to have a concentration of 70 g / L or less. The pH of the hafnium fluoride aqueous solution is preferably 2 or less, and more preferably 1 or less, from the viewpoint of completely dissolving hafnium or hafnium oxide.

[0174] Next, a fluorine-containing hafnium hydrate cake is obtained by neutralizing the hafnium fluoride aqueous solution with an alkaline aqueous solution. Here, the alkaline aqueous solution used to neutralize the hafnium fluoride aqueous solution is preferably 10% to 30% by mass of aqueous ammonia.

[0175] In the neutralization reaction described above, the amount added is preferably such that the NH3 / HF molar ratio is 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the viewpoint of generating hafnium acid compounds that dissolve in amines or dilute ammonia water, the amount added is preferably such that the NH3 / HF molar ratio is 3.0 or higher, more preferably 4.0 or higher, and even more preferably 5.0 or higher. On the other hand, from the viewpoint of cost reduction, the NH3 / HF molar ratio is preferably 100 or lower, more preferably 50 or lower, and even more preferably 40 or lower.

[0176] The addition time in the neutralization reaction described above is preferably 10 minutes or less, more preferably 8 minutes or less, and even more preferably 5 minutes or less.

[0177] The fluorine-containing hafnium hydrate cake obtained by the neutralization reaction described above is decanted with dilute ammonia water using a centrifuge, and the washing is repeated until the amount of liberated fluoride ions is 100 mg / L or less, thereby removing fluoride ions from the fluorine-containing hafnium hydrate cake and obtaining a hafnium-containing precipitate. Since the fluorine-containing hafnium hydrate cake obtained by the neutralization reaction described above contains fluorine compounds such as ammonium fluoride as impurities, it is preferable to remove these. Dilute ammonia water is preferably used as the washing solution for removing fluoride ions.

[0178] The hafnium concentration of the obtained hafnium-containing precipitate can be determined by taking a sample of the precipitate, drying it at 110°C for 24 hours, and then calcining it at 1000°C for 4 hours to produce HfO2. The weight of the HfO2 produced in this way can then be measured, and the hafnium concentration of the hafnium-containing precipitate can be calculated from this weight.

[0179] Then, a tertiary amine compound and pure water are added to the obtained hafnium-containing precipitate and stirred for 10 minutes to obtain a hafnium-containing mixture. Subsequently, 35% by mass of hydrogen peroxide is added to the hafnium-containing mixture and stirred for 30 minutes to obtain a hafnium acid compound-containing solution.

[0180] It is preferable that the tertiary amine compound be mixed in the hafnium-containing mixture so that the concentration of the tertiary amine compound in the mixture is between 0.1% by mass and 30% by mass. Furthermore, it is preferable that the tertiary amine compound be one or more selected from trimethylamine, triethylamine, and tri-n-propylamine.

[0181] The hydrogen peroxide concentration in the hydrogen peroxide solution is preferably 0.5% to 35% by mass. Furthermore, it is preferable to add the hydrogen peroxide so that the molar ratio of hydrogen peroxide to hafnium (H2O2 / Hf) is between 0.6 and 1.5, and more preferably between 0.7 and 1.2, as hydrogen peroxide may decompose during mixing.

[0182] Furthermore, the method for producing a silicon acid-containing liquid, which is a semimetallic acid compound used in the method for producing a metal acid compound-containing liquid of the present invention, will be described below.

[0183] A method for producing a siliconic acid-containing liquid comprises a mixing step of adding an acidic aqueous solution to a silicon-containing raw material and stirring at a temperature of 15°C to 50°C to obtain a mixed liquid containing a silicon compound precursor, and a stirring step of adding a solution containing an organic nitrogen compound to the mixed liquid and stirring at a temperature of 15°C to 50°C to produce a silicon compound-containing liquid.

[0184] First, in the mixing process, an acidic aqueous solution is added to the silicon-containing raw material and stirred at a temperature between 15°C and 50°C to obtain a mixed solution containing a precursor of a silicon compound.

[0185] Examples of silicon-containing raw materials include tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), and sodium silicate. Preferably, the silicon-containing raw material contains at least one of tetraethoxysilane and sodium silicate.

[0186] Examples of acidic aqueous solutions include acetic acid, hydrochloric acid, sulfuric acid, and phosphoric acid. Preferably, the acidic aqueous solution contains at least one of acetic acid, hydrochloric acid, and phosphoric acid.

[0187] When the acidic aqueous solution is acetic acid, the acetic acid content is preferably 0.001% to 3.0% by mass. If the acetic acid content is 0.001% by mass or more, and the silicon-containing raw material is TEOS, the silanol ester group Si-O-CH2-OH3 in TEOS can be efficiently hydrolyzed to form a Si-OH structure. On the other hand, if the acetic acid content is 3.0% by mass or less, it is preferable because the acetic acid content in the final product, the siliconic acid-containing solution, can be reduced. From this viewpoint, the acetic acid content is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more. On the other hand, the acetic acid content is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, even more preferably 2.0% by mass or less, particularly preferably 1.5% by mass or less, even more preferably 1.0% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, even more preferably 0.05% by mass or less, even more preferably 0.04% by mass or less, even more preferably 0.03% by mass or less, and even more preferably 0.02% by mass or less. Unless otherwise specified, the acetic acid content described herein refers to the content when added to the silicon-containing raw material in the mixing process.

[0188] Furthermore, the acetic acid content in the silicon acid-containing solution is preferably 0.02% to 10% by mass. The acetic acid content is more preferably 0.05% or more by mass, even more preferably 0.1% or more by mass, particularly preferably 0.15% or more by mass, and most particularly preferably 0.2% or more by mass. On the other hand, the acetic acid content is more preferably 5% or less by mass, even more preferably 3% or less by mass, particularly preferably 1% or less by mass, and most particularly preferably 0.5% or less by mass.

[0189] Furthermore, the amount of acetic acid added to the silicon-containing raw material preferably has a CH3COOH / Si molar ratio of 0.01 to 0.3, more preferably 0.02 to 0.25, and even more preferably 0.03 to 0.2. Furthermore, the time required for adding acetic acid to the silicon-containing raw material is preferably within 5 minutes, more preferably within 3 minutes, and even more preferably within 1 minute. In addition, the acetic acid content in the siliconic acid-containing solution preferably has a CH3COOH / Si molar ratio of 0.01 to 0.3, more preferably 0.02 to 0.25, and even more preferably 0.03 to 0.2.

[0190] When the acidic aqueous solution added to the silicon-containing raw material is hydrochloric acid, the hydrochloric acid content is preferably 0.001% by mass to 3.0% by mass. If the hydrochloric acid content is 0.001% by mass or more, sodium chloride can be efficiently produced from sodium silicate if the silicon-containing raw material is sodium silicate. On the other hand, if the hydrochloric acid content is 3.0% by mass or less, chlorine is less likely to remain in the final product, the silicon acid-containing liquid, which is preferable. From this viewpoint, the hydrochloric acid content is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more. On the other hand, the hydrochloric acid content is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, even more preferably 2.0% by mass or less, particularly preferably 1.5% by mass or less, even more preferably 1.0% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, even more preferably 0.05% by mass or less, even more preferably 0.04% by mass or less, even more preferably 0.03% by mass or less, and even more preferably 0.02% by mass or less. Unless otherwise specified, the hydrochloric acid content described herein refers to the content when added to the silicon-containing raw material in the mixing step, and is a value calculated by weight of HCl in a 0.5N hydrochloric acid aqueous solution.

[0191] Furthermore, the hydrochloric acid content in the silicate-containing solution is preferably 0.02% to 10% by mass. The hydrochloric acid content is more preferably 0.05% or more by mass, even more preferably 0.1% or more by mass, particularly preferably 0.15% or more by mass, and most preferably 0.2% or more by mass. On the other hand, the hydrochloric acid content is more preferably 5% or less by mass, even more preferably 3% or less by mass, particularly preferably 1% or less by mass, and most preferably 0.5% or less by mass.

[0192] Furthermore, the amount of hydrochloric acid added to the silicon-containing raw material preferably has a molar ratio of HCl / Si of 0.5 to 1.5, more preferably 0.55 to 1.3, and even more preferably 0.6 to 1.1. Furthermore, the time required for adding hydrochloric acid to the silicon-containing raw material is preferably within 10 minutes, more preferably within 5 minutes, and even more preferably within 3 minutes. Furthermore, the hydrochloric acid content in the siliconic acid-containing solution preferably has a molar ratio of HCl / Si of 0.5 to 1.5, more preferably 0.55 to 1.3, and even more preferably 0.6 to 1.1.

[0193] Furthermore, in the mixing process, after adding an acidic aqueous solution to the silicon-containing raw material, the temperature of the mixture during stirring is preferably 15°C to 50°C, more preferably 20°C to 45°C, and even more preferably 25°C to 40°C. If the temperature of the mixture exceeds 50°C, too much water will evaporate from the mixture, causing dehydration condensation between Si-OH groups in the mixture, partially forming SiO2 fine particles. When a solution containing organic nitrogen compounds is added during the stirring process, these particles may not dissolve.

[0194] Furthermore, in the mixing process, the time required for stirring after adding an acidic aqueous solution to the silicon-containing raw material varies depending on the type of silicon-containing raw material, the amount of acidic aqueous solution added, the reduced pressure conditions, etc.

[0195] Specifically, when the silicon-containing raw material is TEOS and the acidic aqueous solution is acetic acid, the stirring time is preferably 30 minutes to 24 hours, more preferably 1 hour to 15 hours, and even more preferably 2 hours to 12 hours.

[0196] Furthermore, if the silicon-containing raw material is sodium silicate and the acidic aqueous solution is hydrochloric acid, the stirring time is preferably 10 minutes to 10 hours, more preferably 30 minutes to 7 hours, and even more preferably 1 hour to 5 hours.

[0197] In this way, by adding an acidic aqueous solution to a silicon-containing raw material and stirring it at a temperature between 15°C and 50°C, a mixed solution containing a precursor of a silicon compound is obtained.

[0198] It is hypothesized that the precursor of silicon compounds, when an acidic aqueous solution is added to a silicon-containing raw material, will result in a higher proportion of linear structures in the resulting silicic acid. This is inferred from the fact that the maximum absorption intensity attributable to the Si-OH stretching vibration increases in the infrared spectral spectrum measured by a Fourier transform infrared spectrophotometer (FT-IR).

[0199] Furthermore, if the silicon-containing raw material is tetraethoxysilane and the acidic aqueous solution is acetic acid, the mixture containing the resulting silicon compound precursor proceeds to the next stirring step.

[0200] On the other hand, if the silicon-containing raw material is sodium silicate and the acidic aqueous solution is hydrochloric acid, the resulting mixture containing the silicon compound precursor requires the following pretreatment before proceeding to the next stirring step. During the stirring described above, some of the Na in the sodium silicate and some of the Cl in the hydrochloric acid react, and the resulting NaCl is contained in the silicon compound precursor. Therefore, it is desirable to remove the NaCl from the silicon compound precursor. As a method for removing the NaCl, first, the mixture containing the silicon compound precursor is placed in a centrifuge tube and centrifuged (4500 rpm, 10 minutes) to recover the precipitated transparent gel. Next, water is added to the recovered transparent gel, placed in a centrifuge tube, and centrifuged (4500 rpm, 20 minutes) multiple times, changing the water each time, thereby removing the NaCl from the silicon compound precursor.

[0201] Next, in the stirring step, a solution containing an organic nitrogen compound is added to the mixture containing a silicon compound precursor, and the mixture is stirred at a temperature between 15°C and 50°C to produce a silicon acid-containing solution.

[0202] Examples of organic nitrogen compounds include primary amines, secondary amines, tertiary amines, and quaternary ammonium salts. Preferably, the organic nitrogen compound contains at least one of the primary amines, secondary amines, and quaternary ammonium salts, and specifically, examples include methylamine, ethylamine, dimethylamine, diethylamine, and tetramethylammonium hydroxide. Alternatively, a solution containing an organic acid may be added to the mixture containing the silicon compound precursor instead of an organic nitrogen compound.

[0203] The amount of organic nitrogen compound added to the mixture containing the silicon compound precursor is preferably such that the amine / Si molar ratio is 0.5 to 15, more preferably 1 to 10, and even more preferably 1.5 to 5. Furthermore, from the viewpoint of generating silicon compounds that dissolve in the organic nitrogen compound, the amount of organic nitrogen compound added is preferably such that the amine / Si molar ratio is 1.7 or higher, more preferably 1.3 or higher, and even more preferably 1.3 or higher. On the other hand, from the viewpoint of cost reduction, the amine / Si molar ratio is preferably 1.5 or lower, more preferably 1.2 or lower, and even more preferably 1 or lower.

[0204] The time required for adding the organic nitrogen compound to the mixture containing the silicon compound precursor is preferably 60 minutes or less, more preferably 30 minutes or less, and even more preferably 10 minutes or less.

[0205] Furthermore, in the stirring step, after adding a solution containing an organic nitrogen compound to a mixture containing a silicon compound precursor, the temperature of the mixture during stirring is preferably 15°C to 50°C, more preferably 20°C to 45°C, and even more preferably 25°C to 40°C. Here, if the temperature of the mixture during stirring exceeds 50°C, the organic nitrogen compound and the like will evaporate, making it difficult to dissolve the silicon compound precursor, and increasing the likelihood that the silicon compound precursor will remain.

[0206] Furthermore, in the stirring step, after adding the solution containing the organic nitrogen compound to the mixture containing the silicon compound precursor, the stirring time is preferably 10 minutes to 24 hours, more preferably 30 minutes to 20 hours, and even more preferably 1 hour to 15 hours.

[0207] Thus, a silicon acid-containing solution can be produced by adding a solution containing an organic nitrogen compound to a mixture containing a silicon compound precursor and stirring it at a temperature between 15°C and 50°C. As mentioned above, it is presumed that the silicon compound precursor is more easily soluble in Si acid because it contains many Si-OH structures.

[0208] Furthermore, the method for producing a rare earth element acid-containing liquid, which is a metal acid compound used in the method for producing a metal acid compound-containing liquid of the present invention, will be described below.

[0209] First, rare earth elements or rare earth element oxides are reacted with hydrofluoric acid (HF), such as an aqueous solution of hydrofluoric acid, to form rare earth element fluorides. These fluorides are then dissolved in water to obtain an aqueous solution of rare earth element fluorides, which is an acidic metal aqueous solution.

[0210] Here, it is preferable to adjust the aqueous solution of rare earth elements by adding water (e.g., pure water) so that it contains 1 to 100 g / L of rare earth elements in terms of rare earth element oxides. In this case, a rare earth element concentration of 1 g / L or more in terms of rare earth element oxides is preferable because it results in a rare earth element acid compound hydrate that is easily soluble in water. Considering productivity, 10 g / L or more is more preferable, and 20 g / L or more is even preferable. On the other hand, a rare earth element concentration of 100 g / L or less in terms of rare earth element oxides is preferable because it results in a rare earth element acid compound hydrate that is easily soluble in water. To more reliably synthesize a rare earth element acid compound hydrate that is easily soluble in water, 90 g / L or less is more preferable, 80 g / L or less is even preferable, and 70 g / L or less is particularly preferable. The pH of the aqueous solution of rare earth elements is preferably 2 or less, and more preferably 1 or less, from the viewpoint of completely dissolving the rare earth elements or rare earth element oxides.

[0211] Next, a fluorine-containing rare earth element hydrate cake is obtained by neutralizing the aqueous solution of rare earth element fluoride with an alkaline aqueous solution. Here, the alkaline aqueous solution used to neutralize the aqueous solution of rare earth element fluoride is preferably 10% to 30% by mass of aqueous ammonia.

[0212] In the neutralization reaction described above, the amount added is preferably such that the molar ratio of NH3 to rare earth elements is 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the viewpoint of generating rare earth element acid compounds that dissolve in amines or dilute ammonia water, the amount added is preferably such that the molar ratio of NH3 to HF is 3.0 or higher, more preferably 4.0 or higher, and even more preferably 5.0 or higher. On the other hand, from the viewpoint of cost reduction, the molar ratio of NH3 to HF is preferably 100 or lower, more preferably 50 or lower, and even more preferably 40 or lower.

[0213] The addition time in the neutralization reaction described above is preferably 10 minutes or less, more preferably 8 minutes or less, and even more preferably 5 minutes or less.

[0214] The fluorine-containing rare earth element hydrate cake obtained by the neutralization reaction described above is decanted with dilute ammonia water using a centrifuge, and the washing is repeated until the amount of liberated fluoride ions is 100 mg / L or less, thereby removing fluoride ions from the fluorine-containing rare earth element hydrate cake and obtaining a rare earth element-containing precipitate. Since the fluorine-containing rare earth element hydrate cake obtained by the neutralization reaction described above contains fluorine compounds such as ammonium fluoride as impurities, it is preferable to remove these. Dilute ammonia water is preferably used as the washing solution for removing fluoride ions.

[0215] The rare earth element concentration in the obtained rare earth element-containing precipitate can be determined by taking a sample of the precipitate, drying it at 110°C for 24 hours, and then calcining it at 1000°C for 4 hours to produce rare earth element oxides. The weight of these rare earth element oxides is then measured, and the rare earth element concentration in the rare earth element-containing precipitate can be calculated from this weight.

[0216] Then, a tertiary amine compound and pure water are added to the obtained rare earth element-containing precipitate and stirred for 10 minutes to obtain a rare earth element-containing mixture. Subsequently, 35% by mass of hydrogen peroxide is added to the rare earth element-containing mixture and stirred for 30 minutes to obtain a rare earth element acid compound-containing solution.

[0217] It is preferable to mix the tertiary amine compound in the rare earth element-containing mixture so that the concentration of the tertiary amine compound is between 0.1% by mass and 30% by mass. Furthermore, it is preferable that the tertiary amine compound is one or more selected from trimethylamine, triethylamine, and tri-n-propylamine.

[0218] The hydrogen peroxide concentration in the hydrogen peroxide solution is preferably 0.5% to 35% by mass. Furthermore, it is preferable to add the hydrogen peroxide so that the molar ratio of hydrogen peroxide to rare earth elements (H2O2 / Hf) is between 0.6 and 1.5, and more preferably between 0.7 and 1.2, as hydrogen peroxide may decompose during mixing.

[0219] Furthermore, the metal acid compounds contained in the metal acid compound-containing solution of the present invention are not limited to the metal acid-containing solutions such as the niobium acid-containing solution, tantalum acid-containing solution, titanic acid-containing solution, molybdic acid-containing solution, tungstic acid-containing solution, zirconium acid-containing solution, hafnium acid-containing solution, and rare earth element acid-containing solution mentioned above, nor are they limited to semimetallic acid-containing solutions such as silicon acid-containing solution. They also include one or more metal acids selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements, as well as metal salt-containing solutions in which alkali metal ions (e.g., lithium ions) are ionically bonded.

[0220] Furthermore, among the metal acid compounds used in the method for producing a metal acid compound-containing solution of the present invention, for example, a niobium acid-containing solution can be produced not only by the method for producing a niobium acid-containing solution described above, but also by the following production method.

[0221] First, niobium, niobium oxide, or niobium hydroxide is reacted with hydrofluoric acid (HF), such as an aqueous solution of hydrofluoric acid, to form niobium fluoride (H2NbF7). Dissolving this in water yields an acidic metal aqueous solution of niobium fluoride. In the case of niobium chloride, the step of dissolving it in hydrofluoric acid can be omitted, and an acidic niobium aqueous solution can be produced by adding water to niobium chloride.

[0222] Here, it is preferable to adjust the niobium fluoride aqueous solution by adding water (e.g., pure water) so that it contains 1 to 100 g / L of niobium in terms of Nb2O5. In this case, a niobium concentration of 1 g / L or more in terms of Nb2O5 is preferable because it results in a water-soluble niobium compound hydrate, and from the perspective of productivity, 10 g / L or more is more preferable, and 20 g / L or more is even more preferable. On the other hand, a niobium concentration of 100 g / L or less in terms of Nb2O5 is also preferable because it results in a water-soluble niobium compound hydrate, and to more reliably synthesize a water-soluble niobium compound hydrate, it is more preferable to have a concentration of 90 g / L or less, even more preferable to have a concentration of 80 g / L or less, and particularly preferable to have a concentration of 70 g / L or less. The pH of the niobium fluoride aqueous solution is preferably 2 or less, and more preferably 1 or less, from the viewpoint of completely dissolving niobium or niobium oxide.

[0223] Next, a fluorine-containing niobium hydrate cake is obtained by neutralizing the niobium fluoride aqueous solution with an alkaline aqueous solution. Here, the alkaline aqueous solution used to neutralize the niobium fluoride aqueous solution is preferably 10% to 30% by mass of aqueous ammonia.

[0224] The ammonia concentration of the ammonia solution used for neutralization is preferably 10% to 30% by mass. A concentration of 10% by mass reduces the likelihood of undissolved niobium, allowing for complete dissolution of niobium or niobic acid in water. On the other hand, a concentration of 30% by mass or less is preferable because it is close to a saturated aqueous solution of ammonia.

[0225] From this viewpoint, the ammonia concentration of the aqueous ammonia solution is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass or more. On the other hand, the ammonia concentration is preferably 30% by mass or less, more preferably 29% by mass or less, and even more preferably 28% by mass or less.

[0226] In the neutralization reaction described above, the amount added is preferably such that the NH3 / Nb molar ratio is 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the viewpoint of generating niobate compounds that dissolve in amines or dilute ammonia water, the amount added is preferably such that the NH3 / HF molar ratio is 3.0 or higher, more preferably 4.0 or higher, and even more preferably 5.0 or higher. On the other hand, from the viewpoint of cost reduction, the NH3 / HF molar ratio is preferably 100 or lower, more preferably 50 or lower, and even more preferably 40 or lower.

[0227] The addition time in the neutralization reaction described above is preferably within 10 minutes, more preferably within 8 minutes, and even more preferably within 5 minutes. In other words, it is preferable to carry out the neutralization reaction in the shortest possible time, for example by adding it all at once, rather than adding it gradually over time. Note that the niobium fluoride aqueous solution and ammonia water can be used at room temperature.

[0228] The fluorine-containing niobium hydrate cake obtained by the neutralization reaction described above is decanted with dilute ammonia water using a centrifuge, and the washing is repeated until the amount of liberated fluoride ions is 100 mg / L or less, thereby removing fluoride ions from the fluorine-containing niobium hydrate cake and obtaining a niobium-containing precipitate. The fluorine-containing niobium hydrate cake obtained by the neutralization reaction described above contains fluorine compounds such as ammonium fluoride as impurities, so it is preferable to remove these.

[0229] The niobium concentration of the obtained niobium-containing precipitate can be determined by taking a sample of the precipitate, drying it at 110°C for 24 hours, and then calcining it at 1000°C for 4 hours to produce Nb2O5. The weight of the resulting Nb2O5 can then be measured, and the niobium concentration of the precipitate can be calculated from this weight.

[0230] The cleaning solution used to remove fluoride ions is preferably dilute ammonia water. Specifically, dilute ammonia water containing 1% to 35% by mass is preferred. With such dilute ammonia water, the ammonia and ammonium ions are appropriate for fluorine, and unnecessary cost increases can be avoided.

[0231] The method for removing fluorine compounds is optional, but methods such as reverse osmosis filtration using ammonia water or pure water, ultrafiltration, microfiltration using membranes, centrifugal separation, and other known methods can be employed. Furthermore, when removing fluoride ions from fluorine-containing niobium hydrate cake, no special temperature control is necessary, and the process can be carried out at room temperature.

[0232] Then, a tertiary amine compound and pure water are added to the obtained niobium-containing precipitate and stirred for 10 minutes to obtain a niobium-containing mixture. Subsequently, 35% by mass of hydrogen peroxide is added to the niobium-containing mixture and stirred for 30 minutes to obtain a niobium acid compound-containing solution.

[0233] From the viewpoint of solubility, it is preferable to mix the tertiary amine compound in the niobium-containing mixture so that the concentration of the tertiary amine compound in the mixture is 30% by mass or less, and more preferably 20% by mass or less. Similarly, from the same viewpoint, it is preferable to mix the tertiary amine compound in the niobium-containing mixture so that the concentration is 0.1% by mass or more, more preferably 1% by mass or more, and may also be 5% by mass or more, or 10% by mass or more. Furthermore, it is preferable that the tertiary amine compound is one or more selected from trimethylamine, triethylamine, and tri-n-propylamine.

[0234] The hydrogen peroxide concentration in the hydrogen peroxide solution is preferably 0.5% to 35% by mass. Furthermore, it is preferable to add the hydrogen peroxide so that the molar ratio of hydrogen peroxide to niobium (H2O2 / Nb) is between 0.6 and 1.5, and more preferably between 0.7 and 1.2, as hydrogen peroxide may decompose during mixing.

[0235] Furthermore, the method for producing the niobate compound-containing liquid described above preferably includes a step of removing hydrogen peroxide from the obtained niobate compound-containing liquid. This is because if hydrogen peroxide is present in the niobate compound-containing liquid, the gas produced by the decomposition of hydrogen peroxide will fill the sealed container, potentially causing the container to expand or, in the worst case, rupture.

[0236] The method for removing hydrogen peroxide is arbitrary, but examples include stirring under open, reduced pressure conditions or reduced pressure drying.

[0237] Furthermore, tantalum acid-containing solutions can also be produced by the following manufacturing method, in addition to the method described above. Note that explanations of parts that overlap with the method for producing niobium-containing solutions described above will be omitted.

[0238] First, tantalum, tantalum oxide, tantalum hydroxide, or tantalum alkoxide is reacted with hydrofluoric acid (HF), such as an aqueous solution of hydrofluoric acid, to form tantalum fluoride (H2TaF7). Dissolving this in water yields an acidic metal aqueous solution of tantalum fluoride. In the case of tantalum chloride, the step of dissolving it in hydrofluoric acid can be omitted, and an acidic tantalum aqueous solution can be produced by adding water to tantalum chloride.

[0239] Here, it is preferable to adjust the aqueous tantalum fluoride solution by adding water (e.g., pure water) so that it contains tantalum in terms of Ta2O5 at a concentration of 1 to 100 g / L. In this case, a tantalum concentration of 1 g / L or more in terms of Ta2O5 is preferable because it results in a tantalate compound hydrate that is easily soluble in water, and from the perspective of productivity, 10 g / L or more is more preferable, and 20 g / L or more is even more preferable. On the other hand, a tantalum concentration of 100 g / L or less in terms of Ta2O5 is also preferable because it results in a tantalate compound hydrate that is easily soluble in water, and to more reliably synthesize a tantalate compound hydrate that is easily soluble in water, 90 g / L or less is more preferable, 80 g / L or less is even more preferable, and 70 g / L or less is particularly preferable. The pH of the aqueous tantalum fluoride solution is preferably 2 or less, and more preferably 1 or less, from the viewpoint of completely dissolving tantalum or tantalum oxide.

[0240] Next, a fluorine-containing tantalum hydrate cake is obtained by neutralizing the tantalum fluoride aqueous solution with an alkaline aqueous solution. Here, the alkaline aqueous solution used to neutralize the tantalum fluoride aqueous solution is preferably 10% to 30% by mass of aqueous ammonia.

[0241] In the neutralization reaction described above, the amount added is preferably such that the NH3 / Ta molar ratio is 95 to 500, more preferably 100 to 450, and even more preferably 110 to 400. Furthermore, from the viewpoint of generating amines and tantalic acid compounds soluble in dilute ammonia water, the amount added is preferably such that the NH3 / HF molar ratio is 3.0 or higher, more preferably 4.0 or higher, and even more preferably 5.0 or higher. On the other hand, from the viewpoint of cost reduction, the NH3 / HF molar ratio is preferably 100 or lower, more preferably 50 or lower, and even more preferably 40 or lower.

[0242] The addition time in the neutralization reaction described above is preferably 10 minutes or less, more preferably 8 minutes or less, and even more preferably 5 minutes or less.

[0243] The fluorine-containing tantalum hydrate cake obtained by the neutralization reaction described above is decanted with dilute ammonia water using a centrifuge, and the washing is repeated until the amount of liberated fluoride ions is 100 mg / L or less, thereby removing fluoride ions from the fluorine-containing tantalum hydrate cake and obtaining a tantalum-containing precipitate. The fluorine-containing tantalum hydrate cake obtained by the neutralization reaction described above contains fluorine compounds such as ammonium fluoride as impurities, so it is preferable to remove these. Dilute ammonia water is preferably used as the washing solution for removing fluoride ions.

[0244] The tantalum concentration of the obtained tantalum-containing precipitate can be determined by taking a sample of the precipitate, drying it at 110°C for 24 hours, and then calcining it at 1000°C for 4 hours to produce Ta2O5. The weight of the Ta2O5 produced in this way can then be measured, and the tantalum concentration of the tantalum-containing precipitate can be calculated from this weight.

[0245] Then, a tertiary amine compound and pure water are added to the obtained tantalum-containing precipitate and stirred for 10 minutes to obtain a tantalum-containing mixture. Subsequently, 35% by mass of hydrogen peroxide is added to the tantalum-containing mixture and stirred for 30 minutes to obtain a tantalum acid compound-containing solution.

[0246] From the viewpoint of solubility, it is preferable to mix the tertiary amine compound in the tantalum-containing mixture so that the concentration of the tertiary amine compound is between 0.1% by mass and 30% by mass. Furthermore, it is preferable that the tertiary amine compound is one or more selected from trimethylamine, triethylamine, and tri-n-propylamine.

[0247] The hydrogen peroxide concentration in the hydrogen peroxide solution is preferably 0.5% to 35% by mass. Furthermore, it is preferable to add the hydrogen peroxide so that the molar ratio of hydrogen peroxide to tantalum (H2O2 / Ta) is between 0.6 and 1.5, and more preferably between 0.7 and 1.2, as hydrogen peroxide may decompose during mixing.

[0248] Furthermore, similar to the method for producing the niobate compound-containing solution described above, it is preferable to include a step of removing hydrogen peroxide from the obtained tantalate compound-containing solution.

[0249] Furthermore, solutions containing titanic acid, molybdic acid, tungstic acid, zirconium acid, hafnium acid, silicon acid, and rare earth element acids, other than niobium acid and tantalum acid, can also be manufactured using the same method. In addition, metal acid compound solutions containing two or more of these solutions, as well as metal salt solutions formed by ionic bonding of these metal oxide solutions with alkali metal ions (e.g., lithium ions), can also be manufactured using the same method.

[0250] The resin used in the method for producing a metal acid compound-containing liquid of the present invention is preferably an anionic water-soluble resin and / or a nonionic water-soluble resin. Furthermore, the resin may contain one or more water-soluble homopolymers selected from the group consisting of acrylic polymers, urethane polymers, styrene polymers, olefin polymers, amide polymers, siloxane polymers, epoxy polymers, vinyl chloride polymers, and vinyl acetate polymers, and / or water-soluble copolymers composed of two or more of these polymers. In particular, it is preferable that the resin contains one or more water-soluble homopolymers of acrylic polymers, styrene polymers, and olefin polymers, and / or water-soluble copolymers composed of two or more of these polymers.

[0251] Water can be used as the solvent in the method for producing a metal acid compound-containing solution of the present invention.

[0252] The metal acid compound-containing liquid of the present invention can be obtained by weighing the above-mentioned metal acid compound, resin, and solvent in predetermined proportions, mixing them, and stirring for 30 minutes.

[0253] The present invention provides a method for producing a complex metal acid compound-containing solution, comprising the steps of: mixing the metal acid compound-containing solution produced by the method for producing a metal acid compound-containing solution of the present invention described above with at least one element A selected from the group consisting of Li, Na, Ma, Al, K, Ca, V, Mn, Fe, Co, Ni, Cu, Zn, Sn, Sr, and Ba to produce a complex metal acid compound-containing solution.

[0254] Specifically, the composite metal acid compound-containing liquid of the present invention is obtained by mixing the metal acid compound-containing liquid of the present invention, produced by the method for producing the metal acid compound-containing liquid of the present invention described above, with at least one element A selected from the group, and maintaining the liquid temperature at an appropriate temperature for a predetermined time while stirring. Here, the at least one element selected from the group that is mixed with the metal acid compound-containing liquid of the present invention produced by the method for producing the metal acid compound-containing liquid of the present invention described above may be in various forms such as oxides, hydroxides, metal complexes, and salts consisting of polyoxometalates and peroxo complexes.

[0255] The present invention provides a method for producing a metal acid compound-containing film, comprising the steps of applying the metal acid compound-containing solution of the present invention to a substrate, drying it, and / or firing it. The metal acid compound-containing solution used in the method for producing a metal acid compound-containing film of the present invention may be produced by the method for producing the metal acid compound-containing solution of the present invention described above.

[0256] Among the metal acid compound-containing films of the present invention, the method for producing a metal acid compound-containing dried film of the present invention comprises a coating step of applying a metal acid compound-containing liquid to the surface of a substrate, and a film drying step of drying the metal acid compound-containing liquid applied to the surface of the substrate to obtain a dried film.

[0257] Specifically, the metal acid compound-containing solution obtained by the method for producing the metal acid compound-containing solution of the present invention described above is dropped onto the surface of the substrate using a syringe while filtering it through, for example, a filter with a pore size of 2 μm, as needed, and then applied by spin coating (700 rpm, 10 seconds, then 1500 rpm, 15 seconds). Next, the substrate is dried at 110°C for 30 minutes to form a dried film containing the metal acid compound of the present invention on the surface of the substrate.

[0258] Among the metal acid compound-containing films of the present invention, the method for producing a metal acid compound-containing calcined film of the present invention comprises a coating step of applying a metal acid compound-containing liquid to the surface of a substrate; a film drying step of drying the metal acid compound-containing liquid applied to the surface of the substrate to obtain a dried film; and a film calcination step of calcining the dried film in the atmosphere at a calcination temperature of 300°C or more and 1,200°C or less, for a calcination time of 1 hour or more and 12 hours or less, to obtain a calcined film.

[0259] Specifically, as described above, a metal acid compound-containing liquid is applied to the surface of the substrate, and the resulting dried film containing the metal acid compound is placed in a standing furnace. The furnace is then fired under air at a firing temperature of 300°C to 1,200°C for a firing time of 1 hour to 12 hours, thereby forming the metal acid compound-containing fired film of the present invention on the surface of the substrate.

[0260] The present invention provides a method for producing a film containing a complex metal acid compound, comprising the steps of applying the complex metal acid compound-containing solution of the present invention to a substrate, drying it, and / or firing it. The composite metal acid compound-containing solution used in the method for producing a composite metal acid compound-containing film of the present invention may be produced by the method for producing the composite metal acid compound-containing solution of the present invention described above.

[0261] Among the composite metal acid compound-containing films of the present invention, the method for producing the composite metal acid compound-containing dried film of the present invention comprises a coating step of applying the composite metal acid compound-containing liquid of the present invention to the surface of a substrate, and a film drying step of drying the composite metal acid compound-containing liquid applied to the surface of the substrate to obtain a dried film, similar to the method for producing the metal acid compound-containing dried film of the present invention.

[0262] Among the composite metal acid compound-containing films of the present invention, the method for producing a composite metal acid compound-containing calcined film of the present invention comprises, similar to the method for producing a metal acid compound-containing calcined film of the present invention, a coating step of applying the composite metal acid compound-containing liquid of the present invention to the surface of a substrate; a film drying step of drying the composite metal acid compound-containing liquid applied to the surface of the substrate to obtain a dried film; and a film calcination step of calcining the dried film in air at a calcination temperature of 300°C or more and 1,200°C or less, for a calcination time of 1 hour or more and 12 hours or less, to obtain a calcined film.

[0263] In this specification, when "X~Y" (where X and Y are any numbers) is used, unless otherwise specified, it includes the meaning of "greater than or equal to X and less than or equal to Y," as well as the meaning of "preferably greater than X" or "preferably less than Y." Similarly, when "greater than or equal to X" (where X is any number) or "less than or equal to Y" (where Y is any number) is used, it also includes the meaning of "preferably greater than X" or "preferably less than Y." [Effects of the Invention]

[0264] The metal acid compound-containing liquid of the present invention does not contain aggregated fine metal acid compounds and exhibits excellent film-forming properties or adhesion to various substrates, particularly plastic film substrates. [Brief explanation of the drawing]

[0265] [Figure 1] This is a table listing the physical properties of the metal acid compound-containing liquids according to Examples 1 to 19 and Comparative Example 1 of the present invention. [Figure 2] This is a table listing the measurement results of the metal acid compound-containing solutions according to Examples 1 to 19 and Comparative Example 1 of the present invention. [Figure 3] This is a table listing the physical properties and measurement results of the metal acid compound-containing liquids according to Examples 2-6, 13, 15, 17-19 and Comparative Example 1 of the present invention. [Best Mode for Carrying Out the Invention]

[0266] The metal acid compound-containing liquid according to embodiments of the present invention will be further described below with reference to the following examples. However, the following examples are not intended to limit the present invention.

[0267] (Example 1) In Example 1, a niobium-containing liquid was prepared, in which the particle size distribution measurement using dynamic light scattering determined that the particle size D50 was 5 nm or less, the niobium concentration was 7.0% by mass in terms of metal (Nb), and the solvent was pure water. An anionic acrylic resin (J-127, manufactured by Arakawa Chemical Co., Ltd.) was prepared, in such quantities that the ratio of the content of the metal acid compound to the content of the resin solid was 0.70, and the ratio of the content of the resin solid to the content of the metal acid compound was 0.05. These were then mixed and stirred to obtain the metal acid compound-containing liquid according to Example 1.

[0268] Specifically, when the metal acid compound-containing solution of Example 1 is considered as 100% by mass, weighing was performed such that the niobium concentration was 2.45% by mass in terms of metal (Nb), the anionic acrylic resin (J-127 manufactured by Arakawa Chemical Co., Ltd.) was 1.5% by mass, the methylamine was 0.7% by mass, and the remainder was pure water. These were mixed and stirred at 25°C for 30 minutes to obtain the metal acid compound-containing solution of Example 1.

[0269] (Example 2) In Example 2, the same manufacturing method as in Example 1 was followed, except that the anionic acrylic resin (Arakawa Chemical Co., Ltd.: J-127) was replaced with an anionic acrylic resin (Arakawa Chemical Co., Ltd.: WC-M-1212), to obtain the metal acid compound-containing solution according to Example 2.

[0270] (Example 3) In Example 3, the same manufacturing method as in Example 1 was followed, except that the anionic acrylic resin (Arakawa Chemical Co., Ltd.: J-127) was replaced with an acrylic resin (Toyo Chem Co., Ltd.: Tokkrill X-4402), to obtain the metal acid compound-containing liquid according to Example 3.

[0271] (Example 4) In Example 4, a production method similar to that of Example 1 was carried out, except that the anionic acrylic resin (manufactured by Arakawa Chemical Industries, Ltd.: J-127) in Example 1 was replaced with an acrylic resin (manufactured by Toyochem Co., Ltd.: Talkril X-4403), and a metal acid compound-containing liquid according to Example 4 was obtained.

[0272] (Example 5) In Example 5, a production method similar to that of Example 1 was carried out, except that the anionic acrylic resin (manufactured by Arakawa Chemical Industries, Ltd.: J-127) in Example 1 was replaced with an anionic styrene resin (manufactured by Arakawa Chemical Industries, Ltd.: WC-M-1216), and a metal acid compound-containing liquid according to Example 5 was obtained.

[0273] (Example 6) In Example 6, a production method similar to that of Example 1 was carried out, except that the anionic acrylic resin (manufactured by Arakawa Chemical Industries, Ltd.: J-127) in Example 1 was replaced with an anionic olefin resin (manufactured by Arakawa Chemical Industries, Ltd.: WC-M-1201), and a metal acid compound-containing liquid according to Example 6 was obtained.

[0274] (Example 7) In Example 7, a production method similar to that of Example 1 was carried out, except that the anionic acrylic resin (manufactured by Arakawa Chemical Industries, Ltd.: J-127) in Example 1 was replaced with a nonionic copolymer polyamide resin (manufactured by Sumitomo Seika Chemicals Co., Ltd.: Sepoljone PA200), and a metal acid compound-containing liquid according to Example 7 was obtained.

[0275] (Example 8) In Example 8, a production method similar to that of Example 1 was carried out, except that the anionic acrylic resin (manufactured by Arakawa Chemical Industries, Ltd.: J-127) in Example 1 was replaced with a nonionic copolymer polyamide resin (manufactured by Sumitomo Seika Chemicals Co., Ltd.: Sepoljone PA150), and a metal acid compound-containing liquid according to Example 8 was obtained.

[0276] (Example 9) [[ID=In Example 9, a manufacturing method similar to that of Example 1 was carried out except that the anionic acrylic resin (manufactured by Arakawa Chemical Industries, Ltd.: J-127) in Example 1 was replaced with a nonionic polyamide elastomer resin (manufactured by Sumitomo Seika Chemicals Co., Ltd.: Sepoljune NE205N), and a metal acid compound-containing liquid according to Example 9 was obtained.

[0277] (Example 10) In Example 10, a manufacturing method similar to that of Example 1 was carried out except that the anionic acrylic resin (manufactured by Arakawa Chemical Industries, Ltd.: J-127) in Example 1 was replaced with a styrene acrylic resin (manufactured by Toyochem Co., Ltd.: Talkril BCX-3101), and a metal acid compound-containing liquid according to Example 10 was obtained.

[0278] (Example 11) In Example 11, a manufacturing method similar to that of Example 1 was carried out except that the anionic acrylic resin (manufactured by Arakawa Chemical Industries, Ltd.: J-127) in Example 1 was replaced with a styrene acrylic resin (manufactured by Toyochem Co., Ltd.: Talkril W-172), and a metal acid compound-containing liquid according to Example 11 was obtained.

[0279] (Example 12) In Example 12, a manufacturing method similar to that of Example 1 was carried out except that the anionic acrylic resin (manufactured by Arakawa Chemical Industries, Ltd.: J-127) in Example 1 was replaced with a styrene acrylic resin (manufactured by Toyochem Co., Ltd.: Talkril W-463), and a metal acid compound-containing liquid according to Example 12 was obtained.

[0280] (Example 13) In Example 13, a manufacturing method similar to that of Example 1 was carried out except that the anionic acrylic resin (manufactured by Arakawa Chemical Industries, Ltd.: J-127) in Example 1 was replaced with a styrene acrylic resin (manufactured by Toyochem Co., Ltd.: Talkril M-4340), and a metal acid compound-containing liquid according to Example 13 was obtained.

[0281] (Example 14) In Example 14, the same manufacturing method as in Example 1 was followed, except that the anionic acrylic resin (Arakawa Chemical Co., Ltd.: J-127) and the anionic ethylene-acrylic acid copolymer ammonium salt resin (Sumitomo Seika Co., Ltd.: Zychsen AC) were substituted, to obtain the metal acid compound-containing liquid according to Example 14.

[0282] (Example 15) In Example 15, the same manufacturing method as in Example 1 was followed, except that the anionic acrylic resin (Arakawa Chemical Co., Ltd.: J-127) from Example 1 was replaced with a nonionic ethylene-acrylic acid copolymer resin (Sumitomo Seika Co., Ltd.: Zychsen A), to obtain the metal acid compound-containing liquid according to Example 15.

[0283] (Example 16) In Example 16, the same manufacturing method as in Example 1 was followed, except that the anionic acrylic resin (Arakawa Chemical Co., Ltd.: J-127) from Example 1 was replaced with a nonionic ethylene-acrylic acid copolymer resin (Sumitomo Seika Co., Ltd.: Zychsen AC-HW-10), to obtain the metal acid compound-containing solution according to Example 16.

[0284] (Example 17) In Example 17, the same manufacturing method as in Example 1 was followed, except that the anionic acrylic resin (Arakawa Chemical Co., Ltd.: J-127) from Example 1 was replaced with a nonionic carboxyl group-containing polyethylene resin (Sumitomo Seika Co., Ltd.: Zychsen L), to obtain the metal acid compound-containing solution according to Example 17.

[0285] (Example 18) In Example 18, the same manufacturing method as in Example 1 was followed, except that the anionic acrylic resin (Arakawa Chemical Co., Ltd.: J-127) was replaced with a polysiloxane-acrylic resin (DIC Corporation: Ceranate WHW-822), to obtain the metal acid compound-containing solution according to Example 18.

[0286] (Example 19) In Example 19, the niobate-containing solution from Example 1 was modified to include a niobate-containing solution, tantalum-containing solution, titanate-containing solution, molybdicate-containing solution, and tungsticate-containing solution, in which the particle size distribution measurement using dynamic light scattering determined that the particle size D50 was 5 nm or less, the metal element concentration (niobium concentration, tantalum concentration, titanium concentration, molybdenum concentration, and tungsten concentration) was 7.0 mass% in terms of metal equivalent (Nb equivalent, Ta equivalent, Ti equivalent, Mo equivalent, and W equivalent), and the solvent was pure water. A metal acid compound-containing solution according to Example 19 was obtained by performing the same manufacturing method as in Example 1, except that a zirconium acid-containing solution in which the particle size distribution measurement using dynamic light scattering method showed a particle size D50 of 100 nm or less, the zirconium concentration was 7.0 mass% in terms of metal equivalent (Zr equivalent), and the solvent was pure water was replaced with a mixed solution of metal acids containing equivalent amounts of each metal acid in terms of metal equivalent weight ratio, and the organic nitrogen compound methylamine 0.7 mass% was replaced with TMAH 0.7 mass%.

[0287] (Comparative Example 1) In Comparative Example 1, a niobium-containing solution, in which the particle size distribution measurement using dynamic light scattering showed a particle size D50 of 5 nm or less, the niobium concentration was 7.0% by mass in terms of metal (Nb), and the solvent was pure water, was weighed so that the niobium concentration was 2.45% by mass in terms of metal (Nb), the methylamine was 0.7% by mass, and the remainder was pure water, when this was set to 100% by mass of the metal acid compound-containing solution of Comparative Example 1. These were then mixed and stirred at 25°C for 30 minutes to obtain the metal acid compound-containing solution of Comparative Example 1.

[0288] The following physical properties were measured for the metal acid compound-containing solutions obtained in Examples 1 to 19 and Comparative Example 1. The measured physical properties and the methods used to measure them are shown below, along with the measurement results in Figures 1 to 3.

[0289] <Elemental analysis> If necessary, the sample was appropriately diluted with dilute hydrochloric acid, and the weight fractions of Nb (based on Nb), Ta (based on Ta), Ti (based on Ti), Mo (based on Mo), W (based on W), Zr (based on Zr), Hf (based on Hf), Si (based on Si), or rare earth elements (based on rare earth elements) were measured using ICP emission spectrometry (Agilent Technologies: AG-5110) in accordance with JIS K0116:2014.

[0290] <Dynamic light scattering method> The particle size distribution was evaluated using a zeta potential, particle size, and molecular weight measurement system (Otsuka Electronics Co., Ltd.: ELSZ-2000) in accordance with JIS Z 8828:2019 "Particle size analysis - Dynamic light scattering method". Immediately before measurement, the solution to be measured was filtered through a 2 μm pore size filter to remove dust and other particles, and then ultrasonically treated with an ultrasonic cleaner (AS ONE Corporation: VS-100III) at 28 kHz for 3 minutes. The particle size (D50) refers to the median diameter (D50), which is the particle size that represents the 50% integrated value of the integrated distribution curve.

[0291] <DLS diameter compatibility test> The initial particle size (D50) of the particles in the metal acid compound-containing liquids for Examples 1 to 19 and Comparative Example 1 was calculated by particle size distribution measurement using the dynamic light scattering method described above. Particles with an initial particle size (D50) of 100 nm or less were evaluated as "○○ (VERY GOOD)", those between 100 nm and 1000 nm were evaluated as "○ (GOOD)", and those above 1000 nm were evaluated as "× (BAD)".

[0292] <DLS diameter time-dependent stability test> The initial particle diameter (D50) of the particles in the metal oxide compound-containing liquids according to Examples 1 to 19 and Comparative Example 1, and the particle diameter over time (D50) of the particles in the metal oxide compound-containing liquids after standing still in a thermostat set at a room temperature of 25°C for 20 days were calculated. Those with an increase in the particle diameter over time (D50) relative to the initial particle diameter (D50) of 10 times or less were evaluated as "〇 (GOOD)", and those with an increase of more than 10 times were evaluated as "× (BAD)". The above-described filtering was performed during the measurement of the "initial particle diameter D50 (nm)", but was not performed during the measurement of the "particle diameter over time D50 (nm)", and only ultrasonic treatment was carried out.

[0293] 〈Test for stability over time〉 After allowing the metal oxide compound-containing liquids according to Examples 1 to 19 and Comparative Example 1 to stand still at a room temperature of 25°C for 20 days, the presence or absence of white precipitate and gelation was visually observed. Those in which no white precipitate or gelation was observed were evaluated as having stability over time and rated as "○ (GOOD)", and those in which any white precipitate or gelation was observed were evaluated as not having stability over time and rated as "× (BAD)". Here, for the determination of gelation, each metal oxide compound-containing liquid was placed in a plastic container, and when the container was turned upside down, a dispersion liquid that did not quickly fall was determined to be gelled.

[0294] 〈Measurement of transmittance〉 4 ml of the metal oxide compound-containing liquids according to Examples 1 to 19 and Comparative Example 1 were placed in a quartz cell with an optical path length of 5.0 mm, and the transmittance of the metal oxide compound-containing liquids according to Examples 1 to 19 and Comparative Example 1 in the wavelength range of 550 nm to 700 nm (specifically, the transmittance at wavelengths of 550 nm, 600 nm, 650 nm, and 700 nm) was measured using a spectrophotometer according to the above-described transmittance measurement conditions. Those with a transmittance of 70%T or more at wavelengths of 550 nm, 600 nm, 650 nm, and 700 nm were evaluated as "〇 (GOOD)", and those with a transmittance of less than 70% were evaluated as "× (BAD)". The "initial transmittance" in FIG. 2 refers to the transmittance of the metal oxide compound-containing liquid adjusted to a liquid temperature of 25°C immediately after being produced. Also, the "transmittance over time" in FIG. 2 refers to the transmittance of the metal oxide compound-containing liquid after standing still in a thermostat set at a room temperature of 25°C for one month.

[0295] <pH measurement> In Examples 1-19 and Comparative Example 1, the pH of the metal acid compound-containing solutions obtained was measured using a pH meter (HORIBA: glass electrode type hydrogen ion concentration indicator D-51) with an electrode (HORIBA: standard ToupH electrode 9615S-10D) after confirming that the solution temperature had stabilized at 25°C. In Figure 2, "initial pH" refers to the pH of the metal acid compound-containing solution immediately after its creation, adjusted to a solution temperature of 25°C. In Figure 2, "pH over time" refers to the pH of the metal acid compound-containing solution after being left standing for one month in a constant temperature incubator set to room temperature of 25°C.

[0296] <Film-forming properties test (glass)> The appearance of the coating film formed on the surface of a glass substrate, which serves as a substitute for a current collector plate, was evaluated by observation with an optical microscope. The metal acid compound-containing solutions of Examples 1-19 and Comparative Example 1 were degreased and washed with acetone using a syringe while filtering through a 2 μm pore size filter, and then dropped onto a dried 50 mm × 50 mm glass substrate. The solution was then applied by spin coating (1,500 rpm, 15 seconds). The coated area was then allowed to air dry to form a coating film on the glass substrate. The glass substrate was observed with an optical microscope (magnification: 40x) in a 15 mm × 15 mm area in the center of the formed coating film. If no bubbles, uneven coating, or cracks were observed, it was evaluated as having excellent film-forming properties and was rated as "○ (GOOD)". If even one or more were observed, it was evaluated as having poor film-forming properties and was rated as "× (BAD)".

[0297] <Adhesion Test (Glass)> A cellophane adhesive tape, as defined in JIS Z 1522:2009, was applied to the coated surface of a glass substrate formed in the same manner as in the film-forming test (glass) described above. After wiping the cellophane adhesive tape from above with a finger, it was quickly peeled off perpendicular to the coated surface, and the presence or absence of peeling of the coated surface on the glass substrate was observed. Samples in which no peeling of the coated surface was observed were evaluated as having excellent adhesion ("〇 (GOOD)"), and samples in which peeling of the coated surface was observed were evaluated as having poor adhesion ("× (BAD)"). The samples used in the adhesion test (glass) were those that had been coated for one day.

[0298] <Film-forming test (PET)> The appearance of the coating film formed on the surface of the PET substrate was evaluated by observation with an optical microscope. The metal acid compound-containing solutions of Examples 2-6, 13, 15, 17-19, and Comparative Example 1 were degreased and washed with acetone using a syringe while filtering through a 2 μm pore size filter, and then dropped onto a dried 50 mm × 50 mm PET substrate. The coating was applied by spin coating (1,500 rpm, 15 seconds). The coated area was then allowed to air dry to form a coating film on the PET substrate. The PET substrate was observed with an optical microscope (magnification: 40x) in a 15 mm × 15 mm area in the center of the formed coating film. If no bubbles, coating irregularities, or cracks were observed, it was evaluated as having excellent film-forming properties and was evaluated as "○ (GOOD)". If even one or more were observed, it was evaluated as having poor film-forming properties and was evaluated as "× (BAD)".

[0299] <Adhesion Test (PET)> A cellophane adhesive tape, as defined in JIS Z 1522:2009, was applied to the coated surface of a PET substrate formed in the same manner as in the film-forming test (PET) described above. After wiping the cellophane adhesive tape from above with a finger, it was quickly peeled off perpendicular to the coated surface, and the presence or absence of coating peeling on the PET substrate was observed. Substrates where no coating peeling was observed were evaluated as having excellent adhesion and were rated as "〇 (GOOD)", while those where coating peeling was observed were evaluated as having poor adhesion and were rated as "× (BAD)". The samples used in the adhesion test (PET) were those that had been coated for one day.

[0300] As shown in Figure 1, the metal acid compound-containing solutions of Examples 1 to 19 contained one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements, a resin, and a solvent. When the particle size distribution D50, measured using dynamic light scattering, was 1000 nm or less, the film-forming properties on glass substrates were good.

[0301] Furthermore, the metal acid compound-containing solutions according to Examples 1 to 19 contained one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements, a resin, and a solvent. When the maximum transmittance in the wavelength range of 550 nm to 700 nm was 70%T or higher, the degree of dispersion was high, the uniformity of the components in the solution was excellent, and the stability over time was also excellent.

[0302] Furthermore, the metal acid compound-containing solutions in Examples 1 to 19 exhibited good stability when the metal acid content in the metal acid compound-containing solution was 0.1% by mass or more and 50% by mass or less in terms of metal equivalent.

[0303] Furthermore, the metal acid compound-containing solutions in Examples 1 to 19 exhibited good stability when the resin content in the metal acid compound-containing solution was 0.1% by mass or more and 60% by mass or less.

[0304] Furthermore, the metal acid compound-containing solutions in Examples 1 to 19 showed good stability when the pH of the metal acid compound-containing solution was greater than 7.

[0305] Furthermore, as shown in Figure 3, the metal acid compound-containing solutions in Examples 2-6, 13, 15, and 17-19 contained one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements, a resin, and a solvent. When the particle size distribution D50, measured using dynamic light scattering, was 1000 nm or less, the film-forming properties on the PET film substrate were good.

[0306] Furthermore, as shown in Figure 3, the metal acid compound-containing solutions in Examples 2-6, 13, 15, and 17-19 contained one or more metal acid compounds selected from the group consisting of Nb, Ta, Ti, Mo, W, Zr, Hf, Si, and rare earth elements, a resin, and a solvent, and exhibited good film formation properties on PET film substrates when the maximum transmittance in the wavelength range of 550 nm to 700 nm was 70%T or higher.

[0307] The inventions disclosed herein include, in addition to the configurations of each invention and embodiment, those specified by modifying these partial configurations to other configurations disclosed herein to the extent applicable, or those specified by adding other configurations disclosed herein to these configurations, or those specified by deleting these partial configurations to the extent that partial effects are obtained, resulting in broader conceptualizations. [Industrial applicability]

[0308] The metal acid compound-containing liquid according to the present invention exhibits excellent film-forming properties and adhesion to a variety of substrates, particularly plastic film substrates, making it suitable as a coating agent for substrates. Furthermore, because the metal acid compound-containing liquid according to the present invention exhibits excellent film-forming properties and adhesion, it can maintain equivalent performance for a longer period than conventional methods and suppress the generation of defective samples with poor film formation. This reduces the amount of waste and lowers energy costs during manufacturing and disposal. In this way, it contributes to the sustainable management and efficient use of natural resources, as well as achieving decarbonization (carbon neutrality).

Claims

1. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce), resin and A solvent containing water, A liquid containing a metal acid compound having, The metal acid compound-containing liquid is characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, the particle size D50 measured by dynamic light scattering is 1000 nm or less, and the pH is greater than 7, and the metal acid compound-containing liquid does not contain citric acid or a salt thereof.

2. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce), resin and A solvent containing water, A liquid containing a metal acid compound having, A metal acid compound-containing liquid characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, the maximum transmittance in the wavelength range of 550 nm to 700 nm is 70%T or more, and the pH is greater than 7, and the metal acid compound-containing liquid does not contain citric acid or a salt thereof.

3. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce), resin and A solvent containing water, Ammonia and, A liquid containing a metal acid compound having, A metal acid compound-containing liquid characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, the particle size D50 measured by dynamic light scattering is 1000 nm or less, and the metal acid compound-containing liquid does not contain citric acid or a salt thereof.

4. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce), resin and A solvent containing water, Ammonia and, A liquid containing a metal acid compound having, The metal acid compound-containing liquid is characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, the maximum transmittance in the wavelength range of 550 nm to 700 nm is 70% T or more, and the metal acid compound-containing liquid does not contain citric acid or a salt thereof.

5. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce), resin and A solvent containing water, Ammonia and, A liquid containing a metal acid compound having, The metal acid compound-containing liquid is characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, the particle size D50 measured by dynamic light scattering is 1000 nm or less, and the pH is greater than 7, and the metal acid compound-containing liquid does not contain citric acid or a salt thereof.

6. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce), resin and A solvent containing water, Ammonia and, A liquid containing a metal acid compound having, A metal acid compound-containing liquid characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, the maximum transmittance in the wavelength range of 550 nm to 700 nm is 70%T or more, and the pH is greater than 7, and the metal acid compound-containing liquid does not contain citric acid or a salt thereof.

7. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce) (excluding metal acid compounds represented by the following formula (I)), resin and A solvent containing water, A liquid containing a metal acid compound having, A metal acid compound-containing liquid characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, the particle size D50 measured by dynamic light scattering is 1000 nm or less, and the metal acid compound-containing liquid does not contain citric acid or a salt thereof. The following formula (I): Cs ｐ M ｑ W １―ｑ O ｒ ・・・(I) [In the formula, M is one or more elements selected from the group consisting of Nb, Ta, Al, and Sc. To express, p satisfies 0.01 ≤ p < 0.3, q satisfies 0.01 ≤ q < 0.5, q and r satisfy 3 < r / (1-q). A metal acid compound having the composition represented by the following:

8. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce) (excluding metal acid compounds represented by the following formula (I)), resin and A solvent containing water, A liquid containing a metal acid compound having, The metal acid compound-containing liquid is characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, the maximum transmittance in the wavelength range of 550 nm to 700 nm is 70% T or more, and the metal acid compound-containing liquid does not contain citric acid or a salt thereof. The following formula (I): Cs ｐ M ｑ W １－ｑ O ｒ ・・・(I) [In the formula, M is one or more elements selected from the group consisting of Nb, Ta, Al, and Sc. To express, p satisfies 0.01 ≤ p < 0.3, q satisfies 0.01 ≤ q < 0.5, q and r satisfy 3 < r / (1-q). A metal acid compound having the composition represented by the following:

9. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce) (excluding niobium oxide colloid particles), resin and A solvent containing water, It has, A metal acid compound-containing liquid characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, the particle size D50 measured by dynamic light scattering is 1000 nm or less, and the pH is greater than 7.

10. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce) (excluding niobium oxide colloid particles), resin and A solvent containing water, It has, A metal acid compound-containing liquid characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, the maximum transmittance in the wavelength range of 550 nm to 700 nm is 70%T or more, and the pH is greater than 7.

11. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce) (excluding niobium oxide colloid particles), resin and A solvent containing water, Ammonia and, It has, A metal acid compound-containing liquid characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, and the particle size D50 measured by dynamic light scattering is 1000 nm or less.

12. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce) (excluding niobium oxide colloid particles), resin and A solvent containing water, Ammonia and, It has, A metal acid compound-containing liquid characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, and the maximum transmittance in the wavelength range of 550 nm to 700 nm is 70% T or more.

13. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce) (excluding niobium oxide colloid particles), resin and A solvent containing water, Ammonia and, It has, A metal acid compound-containing liquid characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, the particle size D50 measured by dynamic light scattering is 1000 nm or less, and the pH is greater than 7.

14. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce) (excluding niobium oxide colloid particles), resin and A solvent containing water, Ammonia and, It has, A metal acid compound-containing liquid characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, the maximum transmittance in the wavelength range of 550 nm to 700 nm is 70%T or more, and the pH is greater than 7.

15. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce) (excluding niobium oxide colloid particles and metal acid compounds represented by the following formula (I)), resin and A solvent containing water, It has, A metal acid compound-containing liquid characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, and the particle size D50 measured by dynamic light scattering is 1000 nm or less. The following formula (I): Cs p M q W 1-q O r ... (I) [In the formula, M is one or more elements selected from the group consisting of Nb, Ta, Al, and Sc. To express, p satisfies 0.01 ≤ p < 0.3, q satisfies 0.01 ≤ q < 0.5, q and r satisfy 3 < r / (1-q). A metal acid compound having the composition represented by the following:

16. One or more metal acid compounds selected from the group consisting of Nb, Ta, Mo, W, and rare earth elements (excluding Ce) (excluding niobium oxide colloid particles and metal acid compounds represented by the following formula (I)), resin and A solvent containing water, It has, A metal acid compound-containing liquid characterized in that the resin is an anionic water-soluble resin and / or a nonionic water-soluble resin, and the maximum transmittance in the wavelength range of 550 nm to 700 nm is 70% T or more. The following formula (I): Cs p M q W 1-q O r ...(I) [In the formula, M is one or more elements selected from the group consisting of Nb, Ta, Al, and Sc. To express, p satisfies 0.01 ≤ p < 0.3, q satisfies 0.01 ≤ q < 0.5, q and r satisfy 3 < r / (1-q). A metal acid compound having the composition represented by the following:

17. The metal acid compound-containing liquid according to any one of claims 1 to 16, characterized in that the resin comprises one or more water-soluble homopolymers selected from the group consisting of acrylic polymers, urethane polymers, styrene polymers, olefin polymers, amide polymers, siloxane polymers, epoxy polymers, vinyl chloride polymers, and vinyl acetate polymers, and / or water-soluble copolymers consisting of two or more of these polymers.

18. The metal acid compound-containing liquid according to any one of claims 1 to 16, characterized in that the metal acid content in the metal acid compound-containing liquid is 0.1% by mass or more and 50% by mass or less in terms of metal.

19. The metal acid compound-containing liquid according to any one of claims 1 to 16, characterized in that the resin content in the metal acid compound-containing liquid is 0.1% by mass or more and 60% by mass or less.

20. A metal acid compound-containing liquid according to any one of claims 1 to 16, further comprising an organic nitrogen compound and / or hydrogen peroxide.

21. A metal acid compound-containing film characterized by containing a metal acid compound and a resin in a metal acid compound-containing liquid according to any one of claims 1 to 16.

22. A coating agent characterized by containing a metal acid compound-containing liquid according to any one of claims 1 to 16.

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