Metal compound liquid dispersion and method for producing metal compound liquid dispersion

Abstract

A metal compound liquid dispersion according to the present invention which has an organic acid, and a metal compound of one or more element types M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, wherein the particle diameter (D50) of the particles in the metal compound liquid dispersion according to a particle size distribution measurement using a dynamic light scattering method is 900 nm or less. A method for producing a metal compound liquid dispersion according to the present invention comprises: a step for obtaining a mixture by mixing and stirring hydrogen peroxide and a halide of said element type M; a step for reacting the mixture with an alkaline compound, and collecting the obtained precipitate; a step for washing the precipitate; and a step for adding pure water and an organic acid to the precipitate, and dissolving the precipitate.

Description

Metal compound dispersion liquid and method for producing metal compound dispersion liquid

[0001] The present invention relates to a metal compound dispersion and a method for producing a metal compound dispersion.

[0002] Aqueous solutions of poorly soluble substances such as tantalum and niobium contain large amounts of ammonia, hydrogen peroxide, and amines classified as hazardous substances under the GHS classification, a standard for assessing the risk of chemical substances. Therefore, it has been extremely difficult to prepare these aqueous solutions into stable solutions over time. Many combinations have resulted in the failure to prepare an aqueous solution, resulting in the precipitation of precipitates. Even if an aqueous solution can be prepared, precipitates quickly precipitate or the solution becomes suspended. Furthermore, even if the precipitate is removed by filtration, precipitates precipitate again or the solution becomes suspended. For example, the organic tantalum aqueous solution disclosed in Patent Document 1 is prepared by dissolving tantalum in lactic acid in an amount eight times the molar amount of tantalum, as well as adding aqueous ammonia and hydrogen peroxide.

[0003] Japanese Patent Application Laid-Open No. 2006-182714

[0004] Thus, metal compound aqueous solutions in which it is considered difficult to increase the concentration of tantalum, niobium, etc., contain large amounts of organic acid, hydrogen peroxide, ammonia, and / or amine, and unless the organic acid contains mainly citric acid, they cannot be prepared into aqueous solutions that are stable over time, and precipitates quickly form or the solution becomes suspended. For this reason, it has been impossible to reduce the contents of organic acid, hydrogen peroxide, ammonia, and / or amine, or to increase the concentration of tantalum, niobium, etc. in the solution.

[0005] Furthermore, in the process for producing a metal compound solution using the conventional complex polymerization method, there is a risk of bumping, particularly in the case of an aqueous solution, which poses a problem in terms of mass productivity.

[0006] In view of the above problems, the present invention provides a metal compound dispersion liquid in which the content of highly hazardous chemical substances is reduced and the concentration of metal compounds is increased, and a method for producing the metal compound dispersion liquid.

[0007] [1] A metal compound dispersion liquid containing a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid, wherein the particle diameter (D50) of particles in the metal compound dispersion liquid is 900 nm or less, as determined by particle diameter distribution measurement using a dynamic light scattering method.

[0008] [2] A metal compound dispersion liquid containing a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid, wherein the metal compound dispersion liquid has a maximum light transmittance of 80%T or more in a wavelength range of 400 nm to 800 nm.

[0009] [3] A metal compound dispersion liquid containing a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid, wherein the particle diameter (D50) of particles in the metal compound dispersion liquid, as determined by particle size distribution measurement using a dynamic light scattering method, is 900 nm or less, and the maximum value of light transmittance of the metal compound dispersion liquid in the wavelength range of 400 nm to 800 nm is 80%T or more.

[0010] [4] The metal compound dispersion liquid according to any one of [1] to [3], further comprising an alkaline compound.

[0011] [5] The metal compound dispersion liquid according to any one of [1] to [4], characterized in that the content of the element species M in the metal compound dispersion liquid is 0.01 mass % or more and 25 mass % or less in terms of atoms of the element species M.

[0012] [6] The metal compound dispersion liquid according to any one of [1] to [5], further containing a metal compound of one or more element species X selected from the group consisting of alkali metals, alkaline earth metals, Cu, Zn, Ag, Sn, Fe, and lanthanoids.

[0013] [7] The metal compound dispersion liquid according to any one of [1] to [6], further containing hydrogen peroxide.

[0014] [8] The metal compound dispersion liquid according to any one of [1] to [7], wherein the organic acid is citric acid, tartaric acid, lactic acid, malic acid, gluconic acid, or lactobionic acid.

[0015] [9] The metal compound dispersion liquid according to any one of [1] to [8], wherein the pH of the metal compound dispersion liquid is 2.0 or more and 10.0 or less.

[0016]

[10] The metal compound dispersion liquid according to [4], characterized in that the molar ratio of the alkaline compound to the element species M(m) (alkaline compound / m) is greater than 0 and less than 10.

[0017]

[11] The hydrogen peroxide (H ２ O ２ ) and the element species M(m) (H ２ O ２ / m) is greater than 0 to 1.

[0018]

[12] The metal compound dispersion liquid according to any one of [1] to

[11] , wherein the molar ratio of the organic acid to the element species M(m) (organic acid / m) is greater than 0 and less than 50.0.

[0019]

[13] The metal compound dispersion liquid according to any one of [1] to

[12] , further comprising fluorine (F), the content of the fluorine (F) being more than 0 mass% and 0.1 mass% or less in terms of fluorine atoms, and the molar ratio (F / m) of the fluorine (F) to the element species M(m) being 0.5 or less.

[0020]

[14] The metal compound dispersion liquid according to any one of [1] to

[12] , further comprising chlorine (Cl), wherein the content of the chlorine (Cl) is more than 0 mass% and 0.1 mass% or less in terms of chlorine atoms, and the molar ratio (Cl / m) of the chlorine (Cl) to the element species M(m) is 0.2 or less.

[0021]

[15] A method for producing a metal compound dispersion liquid, comprising: a step of mixing and stirring a halide of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si with hydrogen peroxide to obtain a mixture; a step of reacting the mixture with an alkaline compound and recovering the obtained precipitate by solid-liquid separation; a step of washing the recovered precipitate with the alkaline compound; and a step of adding pure water and an organic acid to the washed precipitate to dissolve it.

[0022]

[16] The method for producing a metal compound dispersion liquid according to

[15] , wherein the halide is a fluoride and / or a chloride.

[0023]

[17] A metal compound film, which is a coating film of the metal compound dispersion liquid according to any one of [1] to

[14] .

[0024]

[18] A method for producing a metal compound film, comprising the steps of applying a metal compound dispersion produced by the method for producing a metal compound dispersion according to

[15] or

[16] onto a substrate, and drying and / or baking the coating to form a metal compound film on the substrate.

[0025]

[19] A metal carbide powder, which is a carbonized powder of the metal compound dispersion liquid according to any one of [1] to

[14] .

[0026]

[20] A method for producing a metal carbide powder, comprising: a step of drying a metal compound dispersion produced by the method for producing a metal compound dispersion according to

[15] or

[16] to obtain a metal compound powder; and a step of calcining the metal compound powder to obtain a metal carbide powder.

[0027]

[21] A metal carbide film, which is a carbonized film of the metal compound dispersion liquid according to any one of [1] to

[14] .

[0028]

[22] A method for producing a metal carbide film, comprising the steps of applying a metal compound dispersion produced by the method for producing a metal compound dispersion according to

[15] or

[16] onto a substrate and firing the applied metal compound dispersion to form a metal carbide film on the substrate.

[0029] The metal compound dispersion of the present invention, which has been made to solve the above problems, is a metal compound dispersion containing a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid, wherein the particle diameter (D50) of the particles in the metal compound dispersion is 900 nm or less as measured by particle size distribution using dynamic light scattering. The metal compound dispersion of the present invention is a metal compound dispersion containing a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid, wherein the particle diameter (D50) of the particles in the metal compound dispersion is 900 nm or less as measured by particle size distribution using dynamic light scattering, which is preferable in that it reduces the content of highly hazardous chemicals and achieves a high metal compound concentration. Furthermore, the metal compound dispersion of the present invention has high dispersibility despite being a dispersion containing compounds of poorly soluble elements such as Ta, Nb, Hf, and Zr. Of the element species M of the metal compound dispersion of the present invention, Ta, Nb, Hf, and Zr are hardly soluble elements, Ta, Nb, and Hf are even more hardly soluble elements, and Ta and Hf are even more hardly soluble elements.

[0030] In this specification, unless otherwise specified, Si contained in the element species M is a semimetal, but Si compounds are also included in the "metal compound" according to the present invention. In addition, Si compound dispersions are also included in the "metal compound dispersion" according to the present invention.

[0031] The metal compound dispersion of the present invention contains a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si. The metal compound of element species M is considered to exist, for example, as an oxide or a metal-organic complex.

[0032] Specifically, Ta is TaO ３ － , Ta ６ O １９ ２－Nb is thought to exist as an anion such as NbO, a polyoxometalate (polyacid) ion in which multiple tantalum atoms are bonded to oxygen atoms, or a peroxo complex in which hydrogen peroxide is coordinated. ３ － , Nb ６ O １９ ２－ It is believed that Mo exists as an anion such as MoO, a polyoxometalate (polyacid) ion in which multiple niobium atoms are bonded to oxygen atoms, or a peroxo complex in which hydrogen peroxide is coordinated. ４ ２－ It is believed that W exists as an anion such as (W) or as a polyoxometalate (polyacid) ion in which multiple molybdenum atoms and oxygen atoms are bonded. ２ O ７ ) ２－ Ya, (W １２ O １０ ) ８－ It is believed that Ti exists as an anion such as (Ti ３ O ７ ) ２－ Zr is thought to exist as an anion such as ZrO, a polyoxometalate (polyacid) ion in which multiple titanium atoms and oxygen atoms are bonded, or a peroxo complex in which hydrogen peroxide is coordinated. ４ ２－ It is believed that Hf exists as an anion such as HfO, a polyoxometalate (polyacid) ion in which multiple zirconium atoms are bonded to oxygen atoms, or a peroxo complex in which hydrogen peroxide is coordinated. ４ ２－ It is believed that Si exists as an anion such as the above, a polyoxometalate (polyacid) ion in which multiple hafnium atoms are bonded to oxygen atoms, or a peroxo complex in which hydrogen peroxide is coordinated. ４ ４－ , Si ２ O ７ ６－ , Si ３ O ９ ６－ , SiO３ ２－ These are thought to exist as anions such as those shown below, or as polyoxometalate (polyacid) ions in which multiple silicon atoms and oxygen atoms are bonded.

[0033] Furthermore, the metal compound dispersion liquid of the present invention preferably has an element species M content of 0.01% by mass or more and 25% by mass or less, calculated as atoms of the element species M, in terms of excellent transmittance stability in the solution dispersion state. The element species M content is more preferably 0.1% by mass or more and 20% by mass or less, even more preferably 1% by mass or more and 17% by mass or less, and particularly preferably 1.5% by mass or more and 15% by mass or less. The element species M content in the metal compound dispersion liquid of the present invention may be 2.0% by mass or more, 3.0% by mass or more, 4.0% by mass or more, 5.0% by mass or more, 6.0% by mass or more, 7.0% by mass or more, 8.0% by mass or more, or 14% by mass or less, 13% by mass or less, 12% by mass or less, or 10% by mass or less, calculated as atoms of the element species M.

[0034] Here, the content of the element species M in the metal compound dispersion liquid of the present invention is calculated by appropriately diluting the dispersion liquid with dilute hydrochloric acid as necessary, and measuring the mass % of the element species M in terms of atoms using high-frequency inductively coupled plasma spectroscopy (ICP optical emission spectrometry (AG-5110 manufactured by Agilent Technologies)) in accordance with JIS K0116:2014.

[0035] When the element species M contained in the metal compound dispersion liquid of the present invention is a plurality of elements, the total content of the plurality of elements is the content of the element species M in the metal compound dispersion liquid of the present invention. For example, when the element species M is two elements, Ta and Nb, the total content of the tantalum content in terms of Ta atoms and the niobium content in terms of Nb atoms in the metal compound dispersion liquid of the present invention is the content of the element species M in the metal compound dispersion liquid of the present invention.

[0036] The metal compound dispersion of the present invention also contains an organic acid.

[0037] Examples of organic acids include carboxylic acids, polyfunctional carboxylic acids, hydroxycarboxylic acids, and amino acids. Examples of carboxylic acids include butyric acid, formic acid, acetic acid, lauric acid, oleic acid, linoleic acid, and benzoic acid. Examples of polyfunctional carboxylic acids include oxalic acid, succinic acid, malonic acid, maleic acid, glutaric acid, and citric acid. Examples of hydroxycarboxylic acids include lactic acid, tartaric acid, malic acid, gluconic acid, and lactobionic acid. Examples of amino acids include alanine, arginine, aspartic acid, and ethylenediaminetetraacetic acid.

[0038] Furthermore, the metal compound dispersion of the present invention is characterized in that the organic acid is citric acid, tartaric acid, lactic acid, malic acid, gluconic acid, or lactobionic acid. Nitrogen-free organic acids are preferred, such as carboxylic acids, polyfunctional carboxylic acids, and hydroxycarboxylic acids, with citric acid, tartaric acid, lactic acid, malic acid, gluconic acid, and lactobionic acid being more preferred. The organic acid also includes various isomers (structural isomers, optical isomers, etc.) of the above-mentioned compounds. Furthermore, the organic acid may be one or more of the above-mentioned compounds.

[0039] The organic acid content in the metal compound dispersion of the present invention is preferably more than 0% by mass and less than 50% by mass, since this provides excellent transmittance stability in the solution dispersion state. The organic acid content is more preferably 3% by mass or more and 45% by mass or less, and even more preferably 5% by mass or more and 40% by mass or less. Typically, the organic acid content may be 0.5% by mass or more, 0.8% by mass or more, 1.2% by mass or more, 1.8% by mass or more, 2.2% by mass or more, 2.7% by mass or more, 3% by mass or more, 6% by mass or more, 7% by mass or more, 8% by mass or more, 9% by mass or more, 10% by mass or more, or 11% by mass or more. On the other hand, the organic acid content may be 43% by mass or less, 35% by mass or less, 29% by mass or less, 25% by mass or less, 8.5% by mass or less, 7.5% by mass or less, 6.5% by mass or less, 5.5% by mass or less, 4.5% by mass or less, 3.5% by mass or less, or 3% by mass or less. When the metal compound dispersion of the present invention contains two or more organic acids, the organic acid content is the total content of the two or more organic acids contained.

[0040] The method for measuring the organic acid content in the metal compound dispersion of the present invention includes the steps of: １ Examples of the method include H-NMR, gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-mass spectrometry (LC-MS). Of these, measurement of the organic acid content by liquid chromatography (LC) or liquid chromatography-mass spectrometry (LC-MS) is preferred.

[0041] １ The organic acid content in the metal compound dispersion of the present invention can be measured by H-NMR spectroscopy as follows, when the chemical shift of the organic acid can be identified. Specifically, the organic acid content in the metal compound dispersion of the present invention can be determined by the following procedure using a nuclear magnetic resonance spectrometer (AVANCE NEO 600, manufactured by Bruker). 70 μL of the sample solution and 3-(trimethylsilyl)-1-propane-1,1,2,2,3,3-d in heavy water are dissolved in H-NMR spectroscopy. ６ -sodium sulfonate (hereinafter referred to as DSS-d ６ DSS-d ６ A measurement sample is prepared by mixing 70 μL of heavy water solution and 560 μL of heavy water. １ According to the H-NMR spectrum measurement conditions, １ 1 H-NMR spectrum is measured.

[0042] = １ H-NMR spectrum measurement conditions = Magnetic field: 14.1 T (1H 600 MHz) Spectrometer: AVANCE NEO 600 manufactured by Bruker Corporation Measurement and data processing software: TopSpin manufactured by Bruker Corporation NMR probe: Solvent probe (Type: PA BBO 600S3 BBF-H-D-05 Z SP) Solvent: Heavy water Internal sample for chemical shift values ​​and organic acid amounts: DSS-d ６ Chemical shift value standard: DSS-d ６ ​The apex of the peak is set to 0.00 ppm. Spectral center (O1 value - SR value (chemical shift value)): 6 ppm or more and 6.4 ppm or less. Radio frequency pulse intensity: The intensity is such that 15 μs results in a 90-degree pulse relative to the peak of the irradiation center. Radio frequency pulse width: 15 μs. Measurement interval: 84 μs (DW = 42 μs on the software). Number of measurement points: 32,768 points (TD = 65,536 on the software). Number of spectral points (SI on the software): 65,536 points. １ H-NMR spectrum measurement conditions １ The H-NMR spectrum is referred to as the “uncorrected spectrum.”

[0043] The calculation method for the integral value is as described above. １ The FID data measured under the H-NMR spectrum measurement conditions is Fourier transformed using a window function with a full width at half maximum of 0.3 Hz, and the baseline correction described below is performed. １ The H-NMR spectrum was obtained. １ A calculated spectrum is obtained from the H-NMR spectrum using the fitting method described below, and the range of the X-axis including the peak for which the integral value of the calculated spectrum is to be calculated is defined as the "integration range," and the sum of the spectral intensities at all points in the integration range is defined as the "integration value of the target sample." If there are multiple peaks for which the integral values ​​are to be calculated for one target sample, multiple integration ranges may be used.

[0044] The baseline correction method is wider than the integral range, and the X-axis range where the Y-axis values ​​on both sides of a certain X-axis range are close to 0 and the spectrum appears horizontal to the naked eye up to 0.1 ppm inside from both ends of that range is called the "baseline range." The number of baseline ranges is the same as the integral range. Point A is the point on the X-axis and Y-axis where the X-axis value of the uncorrected spectrum is closest to the value obtained by subtracting 0.01 ppm from the maximum value of the baseline range to the point closest to the maximum value of the baseline range, respectively, and Point B is the point on the X-axis and Y-axis where the X-axis value of the uncorrected spectrum is closest to the value obtained by adding 0.01 ppm to the minimum value of the baseline range, respectively. The straight line connecting Point A and Point B is called the "baseline." At each point from the minimum value to the maximum value of the baseline range where the X-axis values ​​are the minimum to maximum, the curve obtained by subtracting the Y-axis values ​​of the uncorrected spectrum from the Y-axis values ​​of the baseline is called the "measured spectrum."

[0045] The method for calculating the integral value from the measured spectrum is to take the sum of the Y-axis values ​​of all points on the measured spectrum from the point closest to the minimum value of the integral range to the point closest to the maximum value, and use this as the integral value within that integral range.

[0046] When it is difficult to apply the above-mentioned method of finding an integral value from an actually measured spectrum due to reasons such as overlapping of multiple peaks, the integral value can be found by performing fitting as follows.

[0047] The range in which the Y-axis values ​​appear to be the values ​​of only the peak for which the integral value is to be calculated, with no other peaks overlapping, is referred to as the "RMSD range." This RMSD range is included in the integral range. Furthermore, if another peak for which the integral value is not to be calculated overlaps within a single integral range, multiple RMSD ranges may be set for that integral range to avoid the peak for which the integral value is not to be calculated. The RMSD ranges for peaks for which the same integral value is to be calculated are included in the same integral range belonging to the peak for which the integral value is to be calculated. Furthermore, overlapping ranges between RMSD ranges are not included. Furthermore, the maximum value of the ratio of the RMSD to the sum of the Y-axis values ​​from the point closest to the minimum to the maximum value of the allowable X-axis value in the integral range is referred to as the "RMSD reference value." The curve represented by the sum of two pseudo-Voigt functions expressed by Equation (1), described below, is referred to as the "calculated spectrum." The root mean square error (hereinafter referred to as RMSD) is calculated for each of four variables (eight variables in total): the chemical shift values ​​of the peak centers of the two pseudo-Voigt functions, the scaling constant, the full width at half maximum, and the ratio of the Lorentzian function, at all points in the entire RMSD range, and the calculated spectrum is fitted using the Excel Solver function so that the ratio of the RMSD to the sum of the Y-axis values ​​from the point closest to the minimum value to the point closest to the maximum value of the integral range is equal to or less than the RMSD reference value.

[0048]

[0049] In the above formula (1), x is １ is the X-axis value (chemical shift value) of the H NMR spectrum, x0 is the chemical shift value of the peak top, S is a scaling coefficient for adjusting the Y-axis value of the peak to the actual measurement, η is the peak area ratio of the Lorentz function (first term) in the range of −∞ (minus infinity) to +∞ (plus infinity), Δ is the full width at half maximum of the peak, π is the constant of the circumference of a circle, ln is a natural logarithm function, and exp is a natural exponential function.

[0050] The above-mentioned "pseudo-Voigt function" is based on "6. Profile functions and pattern decomposition methods" in "Special feature: New developments in powder diffraction methods" in Journal of the Crystallographic Society of Japan, 34, 86 (1992).

[0051] DSS-d ６The calculation of the peak integral value is as follows: Point C is the point on the X-axis and Y-axis where the values ​​on the X-axis and Y-axis are the averages of the values ​​on the X-axis and Y-axis from the point closest to 0.04 ppm to the point closest to 0.05 ppm on the spectrum before correction, and Point D is the point on the X-axis and Y-axis where the values ​​on the X-axis and Y-axis are the averages of the values ​​on the X-axis and Y-axis from the point closest to -0.05 ppm to the point closest to -0.04 ppm on the spectrum before correction. The line connecting Point C and Point D is called "DSS-d ６ The curve obtained by subtracting the Y-axis values ​​of the baseline from the Y-axis values ​​of the uncorrected spectrum at each point between the X-axis values ​​of the chemical shift value -0.05 ppm and 0.05 ppm is called the "DSS-d ６ The sum of the Y-axis values ​​of all points where the X-axis chemical shift value of the measured spectrum of the standard reagent is between -0.05 ppm and 0.05 ppm is called the "DSS-d ６ This is called the "integral value of

[0052] The weight concentration of the target sample is calculated using DSS-d ６ The concentration of DSS-d ６ The weight concentration of the target sample can be calculated from the molecular weight of the target sample and the number of hydrogen atoms in one molecule, the molecular weight of the target sample and the number of hydrogen atoms assigned to the peak obtained by calculating the integral value in one molecule of the target sample, the integral value of the standard reagent, the integral value of the target sample, the volume of the target sample added to the measurement sample, and the specific gravity of the target sample.

[0053] Here, a method for determining the amount of lactic acid contained in the Ta lactate aqueous solution, which is the raw material in the examples described later, will be described below.

[0054] DSS-d used to determine the amount of lactic acid contained in Ta lactate aqueous solution ６ is dissolved in heavy water to a concentration of 10 g / L. The Ta lactate aqueous solution contains two types of lactic acid: "lactic acid contained in the tantalum complex" and "free lactic acid" that is not contained in the tantalum complex.

[0055] First, a method for determining the amount of lactic acid contained in a tantalum complex will be described below.

[0056] The integral value of lactic acid contained in the tantalum complex is defined as follows: baseline range: 4.55 ppm to 8 ppm; integral range: 4.55 ppm to 6.55 ppm; RMSD range 1: 5.14 ppm to 6.55 ppm; RMSD range 2: 4.95 ppm to 5.00 ppm; RMSD range 3: 4.55 ppm to 4.58 ppm; and RMSD reference value: 0.002%, and the sum of the spectral intensities obtained using the above-described method is defined as the "integral value of lactic acid contained in the tantalum complex."

[0057] The weight concentration of lactic acid contained in the tantalum complex in the Ta lactate dispersion is calculated using the lactic acid contained in the tantalum complex as the target sample. ６ Concentration of heavy water solution: 10 g / L, DSS-d in the measurement sample ６ Volume of heavy water solution: 70 μL, DSS-d ６ Molecular weight 224.35, DSS-d ６ The weight concentration of lactic acid contained in the tantalum complex of the Ta lactate dispersion was calculated to be 16.7 mass% from the number of hydrogen atoms in one molecule (9), the molecular weight of lactic acid (90.08), the integral value of the target sample, the integral value of the reference reagent, the volume of the tantalum acid compound dispersion in the measurement sample (70 μL), and the specific gravity of the tantalum acid compound dispersion (1.3274).

[0058] Next, a method for determining the amount of free lactic acid will be described below.

[0059] Free lactic acid is used as the target sample. 4.85 ppm to 4.93 ppm is defined as baseline range 1 for free lactic acid, 4.31 ppm to 4.4 ppm is defined as baseline range 2 for free lactic acid, and 4.05 ppm to 4.28 ppm is defined as baseline range 3 for free lactic acid. 4.85 ppm to 4.93 ppm is defined as integral range 1 for free lactic acid, 4.31 ppm to 4.4 ppm is defined as integral range 2 for free lactic acid, and 4.05 ppm to 4.28 ppm is defined as integral range 3 for free lactic acid. The sum of the three integral values ​​calculated from the measured spectrum obtained from baseline range 1 and integration range 1, the measured spectrum obtained from baseline range 2 and integration range 2, and the measured spectrum obtained from baseline range 3 and integration range 3 is defined as the "integral value of free lactic acid."

[0060] The weight concentration of free lactic acid in the Ta lactate dispersion was calculated using DSS-d ６ Concentration of heavy water solution: 10 g / L, DSS-d in the measurement sample ６ Volume of heavy water solution: 70 μL, DSS-d ６ Molecular weight 224.35, DSS-d ６ The weight concentration of free lactic acid was calculated to be 12.2% by mass from the number of hydrogen atoms in one molecule (9), the molecular weight of lactic acid (90.08), the integral value of the target sample, the integral value of the reference reagent, the volume of the tantalic acid compound dispersion in the measurement sample (70 μL), and the specific gravity of the tantalic acid compound dispersion (1.3274).

[0061] The amount of lactic acid in the tantalum lactate aqueous solution is 28.9 mass % when the lactic acid content of the tantalum complex is 16.7 mass % and the free lactic acid content is 12.2 mass %.

[0062] Furthermore, when the particle size (D50) of the particles in the metal compound dispersion liquid measured by the particle size distribution method using dynamic light scattering is 900nm or less, it is preferable that the particle size (D50) is high dispersibility, stable with little change over time, and has good reactivity with other substances and carbonization, and good film thickness uniformity during film formation.Furthermore, the particle size (D50) is more preferably 800nm ​​or less, more preferably 600nm or less, particularly preferably 500nm or less, more particularly preferably 300nm or less, more particularly preferably 200nm or less, particularly preferably 100nm or less, more preferably 50nm or less, more particularly preferably 30nm or less, even more particularly preferably 20nm or less, even more particularly preferably 10nm or less, particularly more preferably 8nm or less, more particularly more preferably 6nm or less, even more particularly more preferably 4nm or less, even more particularly more preferably 2nm or less, even more particularly more preferably 1nm or less, particularly preferably 1nm or less, more particularly preferably 0.6nm or less, and most preferably more than 0. Furthermore, when the particle diameter (D50) of particles in the metal compound dispersion of the present invention is equal to or less than the particle diameter detection limit of the measuring device by dynamic light scattering or becomes impossible to measure, the particle diameter (D50) of the particles is considered to be equal to or less than the detection limit. On the other hand, when particle precipitation is observed by visual confirmation, it is considered to be above the detection limit and precipitation has occurred. In this way, a liquid in which the particle diameter (D50) of particles in the metal compound dispersion of the present invention is measured using dynamic light scattering and the particle diameter (D50) of the particles is 900 nm or less is considered to be the "metal compound dispersion" of the present invention.

[0063] Dynamic light scattering is a method of measuring the light scattering intensity from particles undergoing Brownian motion by irradiating a solution such as a suspension with light such as a laser beam, and determining particle size and distribution from the temporal fluctuations of this intensity. Specifically, particle size distribution is evaluated using a zeta potential, particle size, and molecular weight measurement system (manufactured by Otsuka Electronics Co., Ltd.: ELSZ-2000) in accordance with JIS Z 8828:2019 "Particle Size Analysis - Dynamic Light Scattering." The solution to be measured is filtered through a 1 μm pore size filter immediately before measurement to remove dust and other particles. Abnormal measured values ​​may be due to the influence of residual dust in the solution. Therefore, if the measurement results of multiple measurement samples taken from the same solution are not reproducible, they may be excluded as abnormal points. The particle size (D50) refers to the median diameter (D50), which is the particle size at 50% of the cumulative distribution curve. Furthermore, in this specification, unless otherwise specified, the "particle diameter (D50)" includes both the particle diameter (D50) of particles in the metal compound dispersion liquid of the present invention adjusted to a liquid temperature of 25°C immediately after production, and the particle diameter (D50) of particles in the metal compound dispersion liquid of the present invention after being left to stand for two weeks or three weeks from the day the metal compound dispersion liquid of the present invention was produced in an incubator set at room temperature of 25°C.

[0064] The metal compound dispersion of the present invention is a metal compound dispersion containing a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid, wherein the metal compound dispersion has a maximum light transmittance of 80% T or more at a wavelength of 400 nm or more and 800 nm or less. Here, the metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and the organic acid contained in the metal compound dispersion of the present invention are as described above, and therefore detailed description thereof will be omitted.

[0065] The metal compound dispersion of the present invention preferably has a maximum light transmittance of 80% T or more at a wavelength of 400 nm or more and 800 nm or less, in terms of high dispersibility and excellent uniformity of the components in the liquid. The maximum light transmittance is more preferably 85% T or more, even more preferably 90% T or more, particularly preferably 95% T or more, even more particularly preferably 97% T or more, even more particularly preferably 98% T or more, even particularly preferably 99% T or more, and most preferably 100% T.

[0066] Furthermore, the metal compound dispersion liquid of the present invention may have a light transmittance of 80% T or more at any one of wavelengths of 400 nm, 500 nm, 600 nm, 700 nm, and 800 nm. The light transmittance may be 85% T or more, 90% T or more, 95% T or more, 97% T or more, 98% T or more, 99% T or more, or 100% T.

[0067] Furthermore, the metal compound dispersion liquid of the present invention may have a minimum light transmittance of 80% T or more at a wavelength of 400 nm or more and 800 nm or less. The minimum light transmittance may be 85% T or more, 90% T or more, 95% T or more, 97% T or more, 98% T or more, 99% T or more, or 100% T.

[0068] Although the measured value of the light transmittance may exceed 100%T due to measurement error or the like, since the theoretical upper limit is 100%T, when the measured value exceeds 100%T, it is considered to be 100%T. Thus, a liquid in which the maximum light transmittance of the metal compound dispersion of the present invention at a wavelength of 400 nm or more and 800 nm or less is 80%T or more is defined as the "metal compound dispersion" of the present invention. Furthermore, unless otherwise specified, in this specification, the "light transmittance" includes both the light transmittance of the metal compound dispersion of the present invention adjusted to a liquid temperature of 25°C immediately after production, and the light transmittance of the metal compound dispersion of the present invention after being left to stand for two or three weeks from the day of production in an incubator set at room temperature of 25°C.

[0069] Here, the above-mentioned light transmittance can be determined by measuring the ultraviolet-visible absorption spectrum (UV-Vis absorption spectrum) of the metal compound dispersion of the present invention in accordance with JIS K 0115, 2004 "General rules for absorptiometric analysis methods" under the following light transmittance measurement conditions.

[0070] =Light transmittance measurement conditions= Measuring device: Ultraviolet-visible-near-infrared spectrophotometer UH4150 (manufactured by Hitachi High-Tech Science Corporation) Measurement mode: Wavelength scan Data mode: %T (transmittance) Measurement wavelength range: 200 nm to 2000 nm Scan speed: 600 nm / min Sampling interval: 2 nm

[0071] The metal compound dispersion of the present invention is a metal compound dispersion containing a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid, wherein the particle diameter (D50) of particles in the metal compound dispersion, as determined by particle size distribution measurement using a dynamic light scattering method, is 900 nm or less, and the maximum light transmittance of the metal compound dispersion in the wavelength range of 400 nm to 800 nm is 80%T or more.

[0072] The metal compound dispersion of the present invention is characterized by further containing one or more metal compounds of element species X selected from the group consisting of alkali metals, alkaline earth metals, Cu, Zn, Ag, Sn, Fe, and lanthanoids. The metal compound dispersion of the present invention may further contain, in addition to the metal compound of element species M described above and the organic acid, one or more metal compounds of element species X selected from the group consisting of alkali metals, alkaline earth metals, Cu, Zn, Ag, Sn, Fe, and lanthanoids. For example, sodium hydroxide. Note that "lanthanoids" refers to 15 elements ranging from La (lanthanum) with atomic number 57 to Lu (lutetium) with atomic number 71.

[0073] It is presumed that the metal compound in the metal compound dispersion of the present invention is present in the dispersion as an ion in an ionic state with an ion of one or more elements X selected from the group consisting of alkali metals, alkaline earth metals, Cu, Zn, Ag, Sn, Fe, and lanthanoids. In the metal compound dispersion of the present invention, hydroxide ions are present as anions, while alkali metals, alkaline earth metals, Cu, Zn, Ag, Sn, Fe, and lanthanoids are thought to be present as cations, and therefore the element species X is thought to be present as a polyoxometalate (polyacid) ion in which a plurality of atoms of the element species X are bonded to oxygen atoms.

[0074] Furthermore, the metal compound dispersion liquid of the present invention is preferably such that the content of element species X in the metal compound dispersion liquid is 0.001% by mass or more and 30% by mass or less in terms of atoms of element species X, since this has excellent transmittance stability in the dispersion state of the solution. Furthermore, the content of element species X may be 0.005% by mass or more and 10% by mass or less, 0.01% by mass or more and 2% by mass or less, or 0.05% by mass or more and 1% by mass or less.

[0075] Here, the content of element species X in the metal compound dispersion liquid of the present invention is calculated by appropriately diluting the dispersion liquid with dilute hydrochloric acid as needed, and measuring the mass % of element species X in atomic terms using high-frequency inductively coupled plasma spectroscopy (ICP optical emission spectrometry (AG-5110 manufactured by Agilent Technologies)) in accordance with JIS K0116:2014, in the same manner as the content of element species M described above.

[0076] When the metal compound dispersion liquid of the present invention contains a plurality of element species X, the total content of the plurality of elements is the content of element species X in the metal compound dispersion liquid of the present invention. For example, when the element species X is two elements, Li and Na, the total content of the lithium content in terms of Li atoms and the sodium content in terms of Na atoms in the metal compound dispersion liquid of the present invention is the content of element species X in the metal compound dispersion liquid of the present invention.

[0077] Furthermore, the element species X preferably contains Li. Furthermore, the element species X is not limited to only one alkali metal element, Li, but is preferably two alkali metal elements, Li and Na or K, or three alkali metal elements, Li, Na, and K. Furthermore, the element species X may be one alkali metal element, Na or K, or two alkali metal elements, Na and K.

[0078] The metal compound dispersion of the present invention is characterized in that it further contains an alkaline compound. The metal compound dispersion of the present invention is obtained by mixing and stirring a halide of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si with hydrogen peroxide, reacting the resulting mixture with an alkaline compound to form a precipitate, and washing the precipitate with the alkaline compound. Therefore, the metal compound dispersion of the present invention may further contain an alkaline compound in addition to the metal compound of element species M and the organic acid described above.

[0079] Specifically, the alkaline compound is preferably one or more compounds selected from ammonia and organic nitrogen compounds. Examples of organic nitrogen compounds include amine compounds, quaternary ammonium compounds, guanidine compounds, and azole compounds. An amine compound or a quaternary ammonium compound is preferred, and methylamine, dimethylamine, ethylamine, diethylamine, tetramethylammonium hydroxide (TMAH), or tetraethylammonium hydroxide (TEAH) is more preferred. The alkaline compound may also be an alkaline solution in which the alkaline compound is dissolved. The alkaline solution is preferably an alkaline aqueous solution, particularly aqueous ammonia.

[0080] The alkaline compound content in the metal compound dispersion of the present invention is preferably more than 0% by mass and less than 5% by mass, since this provides excellent transmittance stability in the solution dispersion state. The alkaline compound content is more preferably 0.01% by mass or more and 4.5% by mass or less, and even more preferably 0.02% by mass or more and 4% by mass or less. Typically, the alkaline compound content may be 0.03% by mass or more, 0.04% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more. Meanwhile, the alkaline compound content may be 3.5% by mass or less, 3% by mass or less, 2.5% by mass or less, or 2% by mass or less. When the metal compound dispersion of the present invention contains two or more alkaline compounds, the alkaline compound content is the total content of the two or more alkaline compounds contained.

[0081] Furthermore, when the alkaline compound is ammonia, the ammonia content in the metal compound dispersion of the present invention is preferably more than 0% by mass and less than 5% by mass, more preferably 0.01% by mass to 4.5% by mass, and even more preferably 0.02% by mass to 4% by mass. From the viewpoints of reactivity and dispersibility, a high ammonia content is desirable. On the other hand, since ammonia is a volatile component, a low ammonia content is desirable, for example, from the viewpoint of suppressing volatilization during coating film formation. Typically, the ammonia content may be 0.03% by mass or more, 0.04% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more. On the other hand, the ammonia content may be 3.5% by mass or less, 3% by mass or less, 2.5% by mass or less, or 2% by mass or less.

[0082] The method for measuring the ammonia content in the metal compound dispersion of the present invention includes a method for adding sodium hydroxide to the dispersion to separate the ammonia by distillation and quantifying the ammonia content using an ion meter; ２Examples of methods for quantifying the ammonia content include a method using a thermal conductivity meter, the Kjeldahl method, gas chromatography (GC), ion chromatography, and gas chromatography mass spectrometry (GC-MS). Particularly, a method for quantifying the ammonia content using an ion meter is preferred. Specifically, as described below, the ammonia content can be measured using an ammonium ion electrode.

[0083] Furthermore, methods for measuring the content of organic nitrogen compounds present in the metal compound dispersion of the present invention include gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), etc. When a low-volatility organic nitrogen compound is contained, it is preferable to measure the content of the organic nitrogen compound by liquid chromatography (LC) or liquid chromatography-mass spectrometry (LC-MS).

[0084] The metal compound dispersion of the present invention is characterized in that it further contains hydrogen peroxide. In the method for producing a metal compound dispersion described below, a complexing reaction of the element species M is promoted by mixing and stirring a halide of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si with hydrogen peroxide. Therefore, the metal compound dispersion of the present invention may further contain hydrogen peroxide in addition to the metal compound of the element species M and the organic acid described above.

[0085] The hydrogen peroxide content in the metal compound dispersion of the present invention is preferably more than 0.001% by mass and less than 5% by mass, as this provides excellent transmittance stability in the solution dispersion state. The hydrogen peroxide content is more preferably 0.002% by mass or more and 4.5% by mass or less, and even more preferably 0.003% by mass or more and 4% by mass or less. Typically, the hydrogen peroxide content may be 0.005% by mass or more, 0.01% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.15% by mass or more, 0.2% by mass or more, 0.3% by mass or more, or 0.5% by mass or more. On the other hand, the hydrogen peroxide content may be 4% by mass or less, 3.5% by mass or less, 3% by mass or less, or 2.5% by mass or less.

[0086] The method for detecting hydrogen peroxide in a metal compound dispersion of the present invention can confirm the hydrogen peroxide content in the dispersion by, for example, using the standard addition method, measuring the relative absorbance intensity with respect to a standard solution of hydrogen peroxide. Specifically, the wavelength region in which a change in absorbance associated with peroxo complex formation is observed is identified from the UV-visible absorption spectra of a standard solution containing a known content of hydrogen peroxide, for example, 1% by mass, and a standard solution containing no added hydrogen peroxide. If the difference in absorbance between the standard solution containing no added hydrogen peroxide and a sample with an unknown hydrogen peroxide content in that wavelength region is less than 1%, it can be confirmed that the sample with an unknown hydrogen peroxide content does not substantially contain hydrogen peroxide. If hydrogen peroxide is present in the dispersion, hydrogen peroxide reacts with, for example, a tantalum polyacid to form a peroxo complex. Therefore, the absence of hydrogen peroxide in the dispersion can be confirmed by checking the difference in absorbance with the standard solution containing no added hydrogen peroxide, as described above. In addition to the above-mentioned standard addition method, the hydrogen peroxide in the dispersion may be qualitatively and quantitatively analyzed by, for example, using a commercially available hydrogen peroxide measurement kit, adding a reagent that undergoes a color reaction with hydrogen peroxide to the dispersion and measuring the color development, or by adding a reagent that undergoes a fluorescent reaction with hydrogen peroxide to the dispersion and measuring the light emission. Specifically, as described below, the hydrogen peroxide content can be measured by measuring at a wavelength of 410 mm using an absorptiometer.

[0087] In the present invention, the term "dispersion" is not limited to a dispersion in which a solute is dispersed or mixed in a solvent in a monomolecular state, but also includes aggregates in which a plurality of molecules are attracted to each other by intermolecular interactions, such as (1) polymer molecules, (2) solvated molecules, (3) molecular clusters, and (4) colloidal particles dispersed in a solvent.

[0088] The metal compound dispersion of the present invention is characterized in that the pH of the metal compound dispersion is 2.0 or more and 10.0 or less. A pH of 2.0 or more and 10.0 or less is preferred in that the polyacid ions contained in the dispersion are stable. The pH of the metal compound dispersion of the present invention is more preferably 2.5 or more and 8.0 or less, even more preferably 3.0 or more and 7.0 or less, and particularly preferably 3.7 or more and 6.5 or less. Typically, the pH may be 2.0 or more, 3.0 or more, 4.0 or more, 5.0 or more, or 5.5 or more. On the other hand, the pH may be 9.0 or less or 8.0 or less. In this specification, unless otherwise specified, "pH" refers to both the pH of the metal compound dispersion of the present invention adjusted to a liquid temperature of 25°C immediately after production and the pH of the metal compound dispersion of the present invention after standing in an incubator set at room temperature of 25°C for two or three weeks from the day of production of the metal compound dispersion.

[0089] Here, the pH of the metal compound dispersion liquid of the present invention is measured by immersing an electrode (manufactured by HORIBA: Standard ToupH electrode 9615S-10D) of a pH meter (manufactured by HORIBA: Glass electrode type hydrogen ion concentration indicator D-51) in the metal compound dispersion liquid of the present invention, and after confirming that the liquid temperature has stabilized at 25°C.

[0090] The metal compound dispersion of the present invention is characterized in that the molar ratio of the alkaline compound to the element species M(m) (alkaline compound / m) is greater than 0 and ranges from 0 to 10.

[0091] The alkaline compound content in the metal compound dispersion of the present invention can be expressed by the molar ratio (alkaline compound / m) of the alkaline compound to the element species M(m). A molar ratio (alkaline compound / m) of more than 0 to 10 is preferred in terms of excellent transmittance stability in the solution dispersion state. Furthermore, the molar ratio (alkaline compound / m) is more preferably 0.01 to 8, even more preferably 0.005 to 6, particularly preferably 0.001 to 1, more particularly preferably 0.0005 to 0.5, and even more particularly preferably 0.0001 to 0.05. Typically, the molar ratio (alkaline compound / m) may be 0.0001 or more, 0.0005 or more, or 0.001 or more. Meanwhile, the molar ratio (alkaline compound / m) may be 6 or less, 1 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.01 or less.

[0092] Here, the "alkaline compound" in the molar ratio (alkaline compound / m) indicates the alkaline compound content (mol) in the metal compound dispersion of the present invention. When two or more alkaline compounds are contained, the alkaline compound content is the total content (mol) of these two or more alkaline compounds. On the other hand, "m" in the molar ratio (alkaline compound / m) indicates the atomic content (mol) of the element species M in the metal compound dispersion of the present invention. When two or more element species M are contained, the atomic content (mol) of the element species M is the total atomic content (mol) of these two or more element species M.

[0093] For example, when the alkaline compound is ammonia, the molar ratio (NH ３ / m) is preferably greater than 0 and 10, more preferably 0.1 or more and 8 or less, even more preferably 0.05 or more and 5 or less, particularly preferably 0.01 or more and 1 or less, more particularly preferably 0.001 or more and 0.5 or less, and even more particularly preferably 0.0005 or more and 0.1 or less. Typically, the molar ratio (NH ３ / m) may be 0.002 or more, 0.006 or more, or 0.01 or more. ３ / m) may be 7 or less, 3 or less, 0.9 or less, 0.4 or less, 0.3 or less, or 0.2 or less.

[0094] Furthermore, when the element species M is Ta, the molar ratio (alkaline compound / Ta) is preferably greater than 0 and up to 10, more preferably 0.01 or more and 8 or less, even more preferably 0.005 or more and 5 or less, particularly preferably 0.001 or more and 1 or less, more particularly preferably 0.0005 or more and 0.5 or less, and even more particularly preferably 0.0001 or more and 0.1 or less. Typically, the molar ratio (alkaline compound / Ta) may be 0.0002 or more, 0.002 or more, or 0.02 or more. On the other hand, the molar ratio (alkaline compound / Ta) may be 7 or less, 5 or less, 1 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.01 or less.

[0095] Furthermore, when the alkaline compound is ammonia and the element species M is Ta, the molar ratio (NH ３ / Ta) is preferably greater than 0 and 10, more preferably 0.1 or more and 8 or less, even more preferably 0.05 or more and 5 or less, particularly preferably 0.01 or more and 1 or less, and even more particularly preferably 0.001 or more and 0.5 or less. Typically, the molar ratio (NH ３ / Ta) may be 0.02 or more, 0.04 or more, or 0.08 or more. ３ / Ta) may be 7 or less, 3 or less, 0.9 or less, 0.4 or less, 0.3 or less, or 0.2 or less.

[0096] In addition, the metal compound dispersion of the present invention contains the hydrogen peroxide (H ２ O ２ ) and the element species M(m) (H ２ O ２ / m) is greater than 0 to 1.

[0097] The content of hydrogen peroxide in the metal compound dispersion of the present invention is ２ O ２ ) and the element species M(m) (H ２ O ２ / m) can be expressed by the molar ratio (H ２ O ２ / m) is preferably greater than 0 to 1 in terms of excellent transmittance stability in the solution dispersion state. ２ O ２ / m) is more preferably 0.1 or more and 0.8 or less, even more preferably 0.05 or more and 0.5 or less, particularly preferably 0.01 or more and 0.1 or less, and even more particularly preferably 0.001 or more and 0.01 or less. Typically, the molar ratio (H ２ O ２ / m) may be 0.005 or more, 0.02 or more, or 0.03 or more. ２ O ２ / m) may be 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, or 0.2 or less.

[0098] Here, the molar ratio (H ２ O ２ / m) in "H ２ O ２ " indicates the hydrogen peroxide content (mol) in the metal compound dispersion of the present invention. ２ O ２ / m), "m" represents the content (mol) of element species M in terms of atoms in the metal compound dispersion liquid of the present invention. When two or more element species M are contained, the content (mol) of element species M in terms of atoms is the total content (mol) of these two or more element species M in terms of atoms.

[0099] For example, when the element species M is Ta, the molar ratio (H ２ O ２ / Ta) is preferably greater than 0 and less than 1, more preferably 0.1 or more and 0.8 or less, even more preferably 0.05 or more and 0.5 or less, particularly preferably 0.01 or more and 0.1 or less, and even more particularly preferably 0.001 or more and 0.01 or less. Typically, the molar ratio (H ２ O ２ / Ta) may be 0.005 or more, 0.02 or more, or 0.03 or more. ２ O ２ / Ta) may be 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, or 0.2 or less.

[0100] The metal compound dispersion of the present invention is characterized in that the molar ratio (organic acid / m) of the organic acid to the element species M(m) is greater than 0 and less than 50.

[0101] The organic acid content in the metal compound dispersion of the present invention can be expressed by the molar ratio (organic acid / m) of the organic acid to the element species M(m). A molar ratio (organic acid / m) of more than 0 to 50 is preferred in terms of excellent transmittance stability in the solution dispersion state. Furthermore, the molar ratio (organic acid / m) is more preferably 0.1 to 40, even more preferably 0.3 to 30, particularly preferably 0.4 to 20, even more particularly preferably 0.5 to 10, and even more preferably 0.6 to 5. Typically, the molar ratio (organic acid / m) may be 0.7 or more, 1 or more, 1.5 or more, 2 or more, 2.5 or more, 3 or more, or 3.5 or more. Meanwhile, the molar ratio (organic acid / m) may be 45 or less, 35 or less, 25 or less, 15 or less, 8 or less, 6 or less, or 5 or less.

[0102] Here, "organic acid" in the molar ratio (organic acid / m) indicates the organic acid content (mol) in the metal compound dispersion of the present invention. Meanwhile, "m" in the molar ratio (organic acid / m) indicates the content (mol) of element species M in atomic terms in the metal compound dispersion of the present invention. Furthermore, when two or more element species M are contained, the content (mol) of element species M in atomic terms is the total content (mol) of these two or more element species M in atomic terms.

[0103] For example, when the element species M is Ta, the molar ratio (organic acid / Ta) is preferably greater than 0 and less than 50, more preferably 0.1 or more and less than 40, even more preferably 0.3 or more and less than 30, particularly preferably 0.4 or more and less than 20, more particularly preferably 0.5 or more and less than 10, and even more preferably 0.6 or more and less than 5. Typically, the molar ratio (organic acid / Ta) may be 0.7 or more, 1 or more, 1.5 or more, 2 or more, 2.5 or more, 3 or more, or 3.5 or more. On the other hand, the molar ratio (organic acid / Ta) may be 45 or less, 35 or less, 25 or less, 15 or less, 8 or less, 6 or less, or 5 or less.

[0104] The metal compound dispersion of the present invention is characterized in that it further contains fluorine (F), the content of the fluorine (F) being more than 0 mass% and not more than 0.1 mass% in terms of fluorine atoms, and the molar ratio (F / m) of the fluorine (F) to the element species M(m) being not more than 0.5. In the method for producing a metal compound dispersion described below, when a fluoride is used as a halide of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, the metal compound dispersion of the present invention may contain fluorine in addition to the metal compound of the element species M and the organic acid.

[0105] The fluorine content in the metal compound dispersion of the present invention, calculated as fluorine atoms, is preferably more than 0% by mass and not more than 0.1% by mass, in terms of excellent transmittance stability in the dispersion state. The fluorine content, calculated as fluorine atoms, may be 0.0005% by mass or more and 0.05% by mass or less, 0.001% by mass or more and 0.03% by mass or less, or 0.005% by mass or more and 0.01% by mass or less.

[0106] Here, the fluorine content in the metal compound dispersion of the present invention can be measured by distilling the solution and then using an absorptiometer based on the lanthanum alizarin complexone absorptiometry method specified in JIS K0102.

[0107] Furthermore, the fluorine content in the metal compound dispersion of the present invention can be expressed by the molar ratio (F / m) of the fluorine (F) to the element species M(m). A molar ratio (F / m) of 0.5 or less is preferred in terms of excellent transmittance stability in the solution dispersion state. Furthermore, the molar ratio (F / m) is more preferably 0.3 or less, even more preferably 0.05 or less, particularly preferably 0.01 or less, and even more particularly preferably 0.001 or less. Typically, the molar ratio (F / m) may be 0.07 or less, 0.06 or less, 0.04 or less, 0.03 or less, 0.007 or less, or 0.004 or less.

[0108] Here, "F" in the molar ratio (F / m) represents the fluorine content (mol) in the metal compound dispersion of the present invention. Meanwhile, "m" in the molar ratio (F / m) represents the content (mol) of element species M in atomic terms in the metal compound dispersion of the present invention. When two or more element species M are contained, the content (mol) of element species M in atomic terms is the total content (mol) of these two or more element species M in atomic terms.

[0109] For example, when the element species M is Ta, the molar ratio (F / Ta) is preferably 0.5 or less, more preferably 0.3 or less, more preferably 0.05 or less, even more preferably 0.01 or less, particularly preferably 0.005 or less, and even more particularly preferably 0.001 or less. Typically, the molar ratio (F / Ta) may be 0.07 or less, 0.06 or less, 0.04 or less, 0.03 or less, 0.007 or less, or 0.004 or less.

[0110] The metal compound dispersion of the present invention is characterized in that it further contains chlorine (Cl), the content of the chlorine (Cl) being more than 0 mass% and not more than 0.1 mass% in terms of chlorine atoms, and the molar ratio (Cl / m) of the chlorine (Cl) to the element species M(m) being not more than 0.2. In the method for producing a metal compound dispersion described below, when a chloride is used as a halide of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, the metal compound dispersion of the present invention may contain chlorine in addition to the metal compound of the element species M and the organic acid.

[0111] The chlorine content in the metal compound dispersion of the present invention, calculated as chlorine atoms, is preferably more than 0% by mass and not more than 0.1% by mass, in terms of chlorine atoms, since the transmittance stability of the dispersion state is excellent. The chlorine content, calculated as chlorine atoms, may be 0.01% by mass or more and 0.05% by mass or less, 0.005% by mass or more and 0.03% by mass or less, or 0.001% by mass or more and 0.005% by mass or less.

[0112] Here, the chlorine content in the metal compound dispersion liquid of the present invention is calculated by diluting the dispersion liquid appropriately with pure water as necessary, and measuring the mass % of chlorine in atomic terms using high-frequency inductively coupled plasma optical emission spectroscopy (ICP optical emission spectroscopy (PS3500DDII manufactured by Hitachi High-Tech Science Corporation)).

[0113] Furthermore, the chlorine content in the metal compound dispersion of the present invention can be expressed by the molar ratio (Cl / m) of the chlorine (Cl) to the element species M(m). A molar ratio (Cl / m) of 0.2 or less is preferable in terms of excellent transmittance stability in the solution dispersion state. Furthermore, the molar ratio (Cl / m) is more preferably 0.1 or less, even more preferably 0.05 or less, particularly preferably 0.01 or less, and even more particularly preferably 0.005 or less. Typically, the molar ratio (Cl / m) may be 0.07 or less, 0.06 or less, 0.04 or less, 0.03 or less, or 0.01 or less.

[0114] Here, "Cl" in the molar ratio (Cl / m) indicates the chlorine content (mol) in the metal compound dispersion of the present invention. Meanwhile, "m" in the molar ratio (Cl / m) indicates the content (mol) of element species M in atomic terms in the metal compound dispersion of the present invention. Furthermore, when two or more element species M are contained, the content (mol) of element species M in atomic terms is the total content (mol) of these two or more element species M in atomic terms.

[0115] For example, when the element species M is Ta, the molar ratio (Cl / Ta) is preferably 0.2 or less, more preferably 0.1 or less, even more preferably 0.05 or less, particularly preferably 0.01 or less, and even more particularly preferably 0.005 or less. Typically, the molar ratio (Cl / Ta) may be 0.07 or less, 0.06 or less, 0.04 or less, 0.03 or less, or 0.01 or less.

[0116] The content of the element species X in the metal compound dispersion liquid of the present invention can be expressed by the molar ratio (x / m) of the element species X (x) to the element species M (m). The molar ratio (x / m) may be 0.001 to 75, 0.002 to 50, 0.01 to 40, 0.2 to 30, 0.5 to 25, 0.8 to 1.5, 0.8 to 1.3, 0.9 to 1.2, or 0.9 to 1.1.

[0117] Here, "x" in the molar ratio (x / m) represents the content (mol) of element species X in atomic terms in the metal compound dispersion of the present invention. When two or more element species X are contained, the content (mol) of element species X in atomic terms is the total content (mol) of these two or more element species X in atomic terms. On the other hand, "m" in the molar ratio (x / m) represents the content (mol) of element species M in atomic terms in the metal compound dispersion of the present invention. When two or more element species M are contained, the content (mol) of element species M in atomic terms is the total content (mol) of these two or more element species M in atomic terms.

[0118] The metal compound dispersion of the present invention may also contain, as an additive, an element or compound thereof that does not constitute the metal compound contained in the metal compound dispersion of the present invention. Examples of such additives include elements or compounds such as Al, V, Mn, Fe, Co, Ni, Cu, Zn, Ge, Sn, and La. Here, examples of the compound include oxides, alkali metal salts of metal acids, alkaline earth metal salts of metal acids, chlorides, metal alkoxides, and polyoxometalates. Furthermore, with regard to the content of additives in the metal compound dispersion of the present invention, when the total number of moles of each element contained in the additives is designated as Z, the molar ratio Z / m of the total number of moles of each element contained in the additives (Z) to the total amount (m) of element species M may be 0.001 to 75, 0.002 to 50, 0.01 to 40, 0.2 to 30, 0.5 to 25, 0.8 to 1.5, 0.8 to 1.3, 0.9 to 1.2, or 0.9 to 1.1. The content of each element corresponding to the additive is calculated by measuring the mass% of each element in atomic terms, similar to the content of element species M described above. Furthermore, since the metal compound dispersion of the present invention is a uniform dispersion, improved uniformity and improved reactivity (reaction rate) are expected even when these compounds are in a suspended state. Furthermore, if these compounds dissolve in the metal compound dispersion of the present invention to form a uniform dispersion, the composite element can be made most reactive.

[0119] The metal compound dispersion of the present invention may also contain pure water as a solvent. Because the metal compounds in the metal compound dispersion of the present invention have high dispersibility in water and good solubility in water, pure water can be used as the solvent. An organic solvent may also be used as the solvent. Examples of organic solvents include alcohol solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, and aliphatic hydrocarbon solvents, and mixtures of these organic solvents with pure water may also be used. Examples of alcohol solvents include alcohols having 5 or fewer carbon atoms (methanol, ethanol, n-propanol, isopropyl alcohol, butanol), high-boiling point solvents, and acetone. It is preferable that the above-mentioned solvents and water are compatible with each other. The titanium compound-containing liquid of the present invention may contain one or more solvents in any ratio as long as stability is not impaired.

[0120] Examples of high-boiling point solvents include polyhydric alcohol solvents and glycol solvents, such as glycerin (boiling point: 290°C), 1,6-hexanediol (boiling point: 250°C), and 1,7-heptanediol (boiling point: 259°C). Examples of glycol-based 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: 460°C or higher), polyethylene glycol (PEG)-polypropylene glycol (PPG) copolymer (boiling point: 460°C or higher), 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 fluorine-based surfactants (boiling point: 180°C or higher), amphoteric fluorine-based surfactants (boiling point: 180°C or higher), nonionic fluorine-based surfactants (boiling point: 180°C or higher), and amine oxides (boiling point: 180°C or higher). The boiling points mentioned above are those at 1 atmosphere.

[0121] Furthermore, the metal compound dispersion of the present invention may contain components other than components derived from metals or metal acids, ammonia, and organic nitrogen compounds (hereinafter referred to as "other components"), provided that the effects of the metal compound dispersion are not impaired. Examples of other components include Al, V, Mn, Fe, Co, Ni, Cu, Zn, Ge, Sn, and La. However, the other components are not limited to these. When the metal compound dispersion of the present invention is taken as 100% by mass, the content of other components is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less. The content of each element corresponding to the other components is calculated by measuring the mass% of each element in atomic terms, similar to the content of the element species M described above. Note that the metal compound dispersion of the present invention is expected to contain unavoidable impurities, although this is not intended. The content of unavoidable impurities is preferably 0.01% by mass or less.

[0122] The metal compound powder of the present invention is characterized by being a powder of the metal compound dispersion liquid of the present invention described above. The metal compound powder of the present invention includes a dried powder obtained by drying the metal compound dispersion liquid of the present invention, for example, by vacuum drying or microwave drying, and a calcined powder obtained by calcining the resulting dried powder. Both dried powder and calcined powder are preferred from the viewpoint of being able to produce a fine powder with a small particle size. The metal compound powder of the present invention also includes a metal compound powder with different physical properties, such as a crystalline structure, produced by vacuum drying, microwave drying, or calcining the metal compound dispersion liquid of the present invention. The metal compound powder may have an amorphous structure, a single crystal structure, or a polycrystalline structure. The method for producing the metal compound powder of the present invention will be described later.

[0123] The metal compound film of the present invention is characterized by being a coating film of the metal compound dispersion of the present invention described above. The metal compound film of the present invention includes a dried film obtained by applying the metal compound dispersion of the present invention to the surface of a substrate and then drying, for example, by vacuum drying or microwave drying, and a fired film obtained by firing the resulting dried film. The metal compound film of the present invention also includes metal compound films with different physical properties, such as crystalline structure, produced by vacuum drying, microwave drying, or firing the metal compound dispersion of the present invention, and may have an amorphous structure, a single crystal structure, or a polycrystalline structure. Because the metal compounds used as raw materials for the metal compound film of the present invention have high chemical resistance, coating the surface of a substrate with the gold oxide compound film of the present invention can improve the high-temperature properties (e.g., protection from thermal degradation of the substrate) and chemical resistance of the substrate. The method for producing the metal compound film of the present invention will be described later.

[0124] The method for producing the above-mentioned metal compound dispersion of the present invention will be described below.

[0125] The method for producing a metal compound dispersion liquid of the present invention is characterized by comprising the steps of: mixing and stirring a halide of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si with hydrogen peroxide to obtain a mixture; reacting the mixture with an alkaline compound and recovering the obtained precipitate by solid-liquid separation; washing the recovered precipitate with the alkaline compound; and adding pure water and an organic acid to the washed precipitate to dissolve it.

[0126] First, a mixture is obtained by mixing and stirring a halide of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si with hydrogen peroxide. Specifically, the mixture is obtained by adding hydrogen peroxide to the halide of the element species M placed in a stirring vessel and mixing and stirring for 1 minute to 5 hours, preferably 5 minutes to 1 hour, and more preferably 5 minutes to 30 minutes. Heating is not required, and the mixture can be carried out at room temperature (25° C.).

[0127] In the mixture thus obtained, the element species M reacts with hydrogen peroxide, a complexation reaction progresses, and the element species M exists as a hydroxide of the element species M. For example, when the element species M is tantalum, it exists as tantalum hydroxide in the mixture.

[0128] The halide is preferably a fluoride and / or chloride of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si. In particular, a fluoride of the element species M is more preferable.

[0129] For example, tantalum fluoride is obtained by adding water (e.g., pure water) to convert tantalum into Ta. ２ O ５ It is preferable to adjust the tantalum content to 1 to 100 g / L in terms of Ta. ２ O ５ When the tantalum content is 1 g / L or more in terms of Ta, the resulting tantalic acid compound hydrate is easily soluble in water, and when productivity is taken into consideration, the tantalum content is more preferably 10 g / L or more, and even more preferably 20 g / L or more. ２ O ５ A converted concentration of 100 g / L or less is preferable because it results in a tantalic acid compound hydrate that is highly soluble in water. In order to more reliably synthesize a tantalic acid compound hydrate that is highly soluble in water, a concentration of 90 g / L or less is more preferable, a concentration of 80 g / L or less is even more preferable, and a concentration of 70 g / L or less is particularly preferable.

[0130] The hydrogen peroxide content in the mixture is preferably more than 0% by mass and not more than 10% by mass, more preferably 0.001% by mass or more and not more than 5% by mass, even more preferably 0.01% by mass or more and not more than 1% by mass, and particularly preferably 0.1% by mass or more and not more than 0.8% by mass. Typically, the hydrogen peroxide content may be 0.01% by mass or more, 0.05% by mass or more, 0.1% by mass or more, or 0.5% by mass or more. On the other hand, the hydrogen peroxide content may be 8% by mass or less, 6% by mass or less, 4% by mass or less, or 2% by mass or less.

[0131] The hydrogen peroxide (H ２ O ２ ) content is the molar ratio (H ２O ２ / m) can be expressed by the molar ratio (H ２ O ２ / m) is preferably more than 0.5 and not more than 3, more preferably 0.7 or more and 1.3 or less, and even more preferably 0.8 or more and 2.5 or less. Typically, the molar ratio (H ２ O ２ / m) may be 0.65 or more, 0.7 or more, or 0.75 or more. ２ O ２ / m) may be 2.2 or less, 1.8 or less, 1.5 or less, 1.3 or less, 1.2 or less, or 1.1 or less.

[0132] Here, the molar ratio (H ２ O ２ / m) in "H ２ O ２ " indicates the hydrogen peroxide content (mol) in the mixture. Meanwhile, the molar ratio (H ２ O ２ / m), "m" represents the content (mol) of element species M in the mixture in terms of atoms. When two or more element species M are contained, the content (mol) of element species M in terms of atoms is the total content (mol) of these two or more element species M in terms of atoms.

[0133] Specifically, when the halide is tantalum fluoride, the molar ratio of hydrogen peroxide to tantalum (H ２ O ２ / Ta) is preferably more than 0.5 and not more than 1.5, more preferably 0.7 or more and 1.3 or less, and even more preferably 0.8 or more and 1.2 or less. Typically, the molar ratio (H ２ O ２ / Ta) may be 0.65 or more, 0.7 or more, or 0.75 or more. ２ O ２ / Ta) may be 1.3 or less, 1.2 or less, or 1.1 or less.

[0134] Next, the resulting mixture is reacted with an alkaline compound, and the resulting precipitate is subjected to solid-liquid separation and recovered. Specifically, the alkaline compound is added to the resulting mixture at a rate of, for example, 1000 mL / min to obtain a white precipitate. The white precipitate is then placed in a centrifuge tube and centrifuged at 4500 rpm for 20 minutes, after which the supernatant is discarded and only the white precipitate is recovered.

[0135] The precipitate recovered in this manner is a precipitate of complexed element species M that exists as a result of the reaction of the complexed element species M with the alkaline compound. For example, when the element species M is tantalum, the precipitate is a precipitate of complexed tantalum hydroxide.

[0136] The alkaline compound used to react with the complexed element species M is preferably one or more compounds selected from ammonia and organic nitrogen compounds. Examples of organic nitrogen compounds include amine compounds, quaternary ammonium compounds, guanidine compounds, and azole compounds. An amine compound or a quaternary ammonium compound is preferred, and methylamine, dimethylamine, tetramethylammonium hydroxide (TMAH), or tetraethylammonium hydroxide (TEAH) is more preferred. The alkaline compound may also be an alkaline solution in which the alkaline compound is dissolved. The alkaline solution is preferably an alkaline aqueous solution, particularly aqueous ammonia.

[0137] The content of the alkaline compound used to react with the complexed element species M is preferably more than 0% by mass and less than 50% by mass, and more preferably 0.01% by mass or more and 15% by mass or less. From the viewpoints of reactivity and dispersibility, a higher content of the alkaline compound is desirable. Typically, the content of the alkaline compound may be 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, 8% by mass or more, or 10% by mass or more. On the other hand, the content of the alkaline compound may be 30% by mass or less, 25% by mass or less, 20% by mass or less, or 10% by mass or less.

[0138] When the alkaline compound used to react with the complexed element species M is ammonia water, the ammonia content is preferably more than 0% by mass and less than 50% by mass, and more preferably 0.01% by mass or more and 15% by mass or less. From the viewpoint of reactivity and dispersibility, a higher ammonia content is desirable. Typically, the ammonia content may be 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, 8% by mass or more, or 10% by mass or more. On the other hand, the ammonia content may be 30% by mass or less, 25% by mass or less, 20% by mass or less, or 10% by mass or less.

[0139] The recovered precipitate is then washed with an alkaline compound. Specifically, the alkaline compound is added to the precipitate, the mixture is mixed, and the mixture is placed in a centrifuge tube again and centrifuged at 4,500 rpm for 20 minutes. The supernatant is then discarded, and only the precipitate is recovered.

[0140] By repeating this series of operations multiple times (for example, three times), it is possible to remove excess alkaline compounds and hydrogen peroxide contained in the precipitate, as well as excess fluorine and halogen elements such as chlorine.

[0141] Removing excess alkaline compounds from the precipitate makes it easier to use in terms of safety and workability. Also, removing excess hydrogen peroxide from the precipitate can suppress changes in the precipitate due to the evaporation of hydrogen peroxide, making it easier to use in terms of safety and compliance with regulations.

[0142] The alkaline compound used to wash the recovered precipitate is preferably one or more compounds selected from ammonia and organic nitrogen compounds. Examples of organic nitrogen compounds include amine compounds, quaternary ammonium compounds, guanidine compounds, and azole compounds. An amine compound or a quaternary ammonium compound is preferred, and methylamine, dimethylamine, ethylamine, diethylamine, tetramethylammonium hydroxide (TMAH), or tetraethylammonium hydroxide (TEAH) is more preferred. The alkaline compound may also be an alkaline solution in which the alkaline compound is dissolved. The alkaline solution is preferably an alkaline aqueous solution, particularly ammonia water.

[0143] The alkaline compound content used to wash the recovered precipitate is preferably more than 0% by mass and less than 50% by mass, and more preferably 0.01% by mass or more and 4% by mass or less. From the viewpoints of reactivity and dispersibility, a higher alkaline compound content is desirable. Typically, the alkaline compound content may be 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, 8% by mass or more, or 10% by mass or more. On the other hand, the alkaline compound content may be 30% by mass or less, 25% by mass or less, 20% by mass or less, or 10% by mass or less.

[0144] When the alkaline compound used to wash the recovered precipitate is ammonia water, the ammonia content is preferably more than 0% by mass and less than 50% by mass, and more preferably 0.01% by mass or more and 4% by mass or less. From the viewpoint of reactivity and dispersibility, a higher ammonia content is desirable. Typically, the ammonia content may be 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, 8% by mass or more, or 10% by mass or more. On the other hand, the ammonia content may be 30% by mass or less, 25% by mass or less, 20% by mass or less, or 10% by mass or less.

[0145] Then, pure water and an organic acid are added to the washed precipitate to dissolve it. Specifically, pure water and an organic acid are added to the washed precipitate, and the precipitate is dissolved by, for example, ultrasonic treatment or a shaker, to obtain the metal compound dispersion liquid of the present invention.

[0146] Examples of organic acids added to the washed precipitate include carboxylic acids, polyfunctional carboxylic acids, hydroxycarboxylic acids, and amino acids. Examples of carboxylic acids include butyric acid, formic acid, acetic acid, lauric acid, oleic acid, linoleic acid, and benzoic acid. Examples of polyfunctional carboxylic acids include oxalic acid, succinic acid, malonic acid, maleic acid, glutaric acid, and citric acid. Examples of hydroxycarboxylic acids include lactic acid, tartaric acid, malic acid, gluconic acid, and lactobionic acid. Examples of amino acids include alanine, arginine, aspartic acid, and ethylenediaminetetraacetic acid. Organic acids that do not contain nitrogen atoms are particularly preferred, such as carboxylic acids, polyfunctional carboxylic acids, and hydroxycarboxylic acids, with citric acid, tartaric acid, lactic acid, malic acid, gluconic acid, and lactobionic acid being more preferred. Organic acids also include various isomers (structural isomers, optical isomers, etc.) of the above-mentioned compounds. Furthermore, one or more organic acids of the above-mentioned compounds may be used.

[0147] The content of the organic acid added to the washed precipitate is preferably more than 0% by mass and less than 50% by mass, since this provides excellent transmittance stability in the solution dispersion state. The organic acid content is more preferably 3% by mass or more and 45% by mass or less, and even more preferably 5% by mass or more and 40% by mass or less. Typically, the organic acid content may be 0.5% by mass or more, 0.8% by mass or more, 1.2% by mass or more, 1.8% by mass or more, 2.2% by mass or more, 2.7% by mass or more, 3% by mass or more, 6% by mass or more, 7% by mass or more, 8% by mass or more, 9% by mass or more, 10% by mass or more, or 11% by mass or more. Meanwhile, the organic acid agent content may be 43% by mass or less, 35% by mass or less, 29% by mass or less, 25% by mass or less, 8.5% by mass or less, 7.5% by mass or less, 6.5% by mass or less, 5.5% by mass or less, 4.5% by mass or less, 3.5% by mass or less, or 3% by mass or less. Here, when the organic acid added is a mixture of two or more organic acids, the content of the organic acid is the total content of the two or more organic acids added.

[0148] The content of the organic acid added to the washed precipitate can be expressed by the molar ratio (organic acid / m). It is preferable to add the organic acid so that the molar ratio (organic acid / m) is greater than 0 and less than 50. From the viewpoint of the stability and cost reduction of the metal compound dispersion liquid of the present invention, the molar ratio is more preferably 0.1 to 40, even more preferably 0.3 to 30, particularly preferably 0.4 to 20, even more particularly preferably 0.5 to 10, and even more preferably 0.6 to 5. Typically, the molar ratio (organic acid / m) may be 0.7 or more, 1 or more, 1.5 or more, 2 or more, 2.5 or more, 3 or more, or 3.5 or more. On the other hand, the molar ratio (organic acid / m) may be 45 or less, 35 or less, 25 or less, 15 or less, 8 or less, 6 or less, or 5 or less.

[0149] Here, "organic acid" in the molar ratio (organic acid / m) indicates the content of organic acid in the metal compound dispersion of the present invention. When two or more organic acids are contained, the content (mol) of organic acid is the total content (mol) of these two or more organic acids. On the other hand, "m" in the molar ratio (organic acid / m) indicates the content (mol) of element species M in atomic terms in the metal compound dispersion of the present invention. When two or more element species M are contained, the content (mol) of element species M in atomic terms is the total content (mol) of these two or more element species M in atomic terms.

[0150] For example, when the element species M to be mixed is tantalum hydroxide, the organic acid is preferably added so that the molar ratio of the organic acid to tantalum (organic acid / Ta) is greater than 0 and less than 50. From the viewpoint of the stability and cost reduction of the metal compound dispersion liquid of the present invention, the molar ratio is more preferably 0.1 to 40, even more preferably 0.3 to 30, particularly preferably 0.4 to 20, even more particularly preferably 0.5 to 10, and still more preferably 0.6 to 5. Typically, the molar ratio (organic acid / Ta) may be 0.7 or more, 1 or more, 1.5 or more, 2 or more, 2.5 or more, 3 or more, or 3.5 or more. On the other hand, the molar ratio (organic acid / Ta) may be 45 or less, 35 or less, 25 or less, 15 or less, 8 or less, 6 or less, or 5 or less.

[0151] In addition to the above-mentioned pure water and organic acids, the following organic solvents can be used as the solvent to be added to the washed precipitate. Examples of organic solvents include alcohol solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, and aliphatic hydrocarbon solvents, and the solvent may be a mixture of these organic solvents and pure water. Examples of alcohol solvents include alcohols having 5 or less carbon atoms (methanol, ethanol, n-propanol, isopropyl alcohol, butanol, ethylene glycol, and propylene glycol), acetone, and high-boiling point solvents. It is preferable that the above-mentioned solvents and water are compatible with each other.

[0152] Examples of high-boiling point solvents include polyhydric alcohol solvents and glycol solvents, such as glycerin (boiling point: 290°C), 1,6-hexanediol (boiling point: 250°C), and 1,7-heptanediol (boiling point: 259°C). Examples of glycol-based 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: 460°C or higher), polyethylene glycol (PEG)-polypropylene glycol (PPG) copolymer (boiling point: 460°C or higher), 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 fluorine-based surfactants (boiling point: 180°C or higher), amphoteric fluorine-based surfactants (boiling point: 180°C or higher), nonionic fluorine-based surfactants (boiling point: 180°C or higher), and amine oxides (boiling point: 180°C or higher). The boiling points mentioned above are those at 1 atmosphere.

[0153] In addition to the solvent added to the washed precipitate, a resin may be added. The resin may be a polyolefin compound, a polyvinyl compound, or the like. The resin added to the solvent may be an anionic water-soluble resin and / or a nonionic water-soluble resin.

[0154] Here, the cationic water-soluble resin is a resin that has a positive charge in the polymer in water at pH = 7, and has any functional group such as an amino group, an imino group, a tertiary amine group, a quaternary ammonium group, a hydrazino group, an azole group, an alkylated azole group, an imidazole group, or an imidazolium group. The anionic water-soluble resin is a resin that has a negative charge in the polymer in water at pH = 7, and has any functional group such as a carboxyl group, a sulfonic acid group, a sulfate ester group, or a phosphate ester group. The nonionic water-soluble resin is a resin that does not fall under the category of the above-mentioned cationic water-soluble resin or anionic water-soluble resin, and has any functional group such as a hydroxyl group, an ether group, or an amide group in the polymer.

[0155] Furthermore, these resins 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 consisting of two or more of these polymers. In particular, it is preferable for the resins to contain one or more water-soluble homopolymers of acrylic polymers, styrene polymers, and olefin polymers, and / or water-soluble copolymers consisting of two or more of these polymers.

[0156] Furthermore, as another example of the method for producing a metal compound dispersion liquid of the present invention, a method for producing a metal compound dispersion liquid of the present invention containing a metal compound of one or more element species X selected from the group consisting of alkali metals, alkaline earth metals, Cu, Zn, Ag, Sn, Fe, and lanthanoids will be described below.

[0157] When the element species X is one or more selected from the group consisting of alkali metals and alkaline earth metals, it is preferable to mix and stir a halide of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si with hydrogen peroxide, and then add one or more element species X selected from the group consisting of alkali metals and alkaline earth metals to the resulting mixture and mix and stir. Here, the type of alkali metal or alkaline earth metal compound added to the mixture is not limited, but hydroxides, oxides, carbonates, hydrochlorides, sulfates, nitrates, and phosphates are preferred in terms of maintaining high dispersibility, and hydroxides are more preferred. Examples include sodium hydroxide, potassium hydroxide, lithium hydroxide, and calcium hydroxide.

[0158] The subsequent production steps are carried out in the same manner as in the above-described method for producing a metal compound dispersion of the present invention, thereby obtaining a metal compound dispersion of the present invention containing a metal compound of one or more element species X selected from the group consisting of alkali metals and alkaline earth metals.

[0159] When the element species X is one or more selected from the group consisting of Cu, Zn, Ag, Sn, Fe, and lanthanoids, it is preferable to mix and stir a halide of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si with one or more element species X selected from the group consisting of Cu, Zn, Ag, Sn, Fe, and lanthanoids, and then add hydrogen peroxide and mix and stir to obtain a mixture. Here, the type of compound of Cu, Zn, Ag, Sn, Fe, or lanthanoid to be mixed with the halide of the element species M is not limited, but oxides, hydroxides, carbonates, hydrochlorides, sulfates, nitrates, and phosphates are preferred in terms of maintaining high dispersibility, and hydrochlorides are more preferred. Examples include copper chloride, zinc chloride, and tin chloride.

[0160] The subsequent production steps are carried out in the same manner as in the above-described method for producing a metal compound dispersion of the present invention, whereby a metal compound dispersion of the present invention containing one or more metal compounds of element species X selected from the group consisting of Cu, Zn, Ag, Sn, Fe, and lanthanoids can be obtained.

[0161] The method for producing a metal compound powder containing a metal compound in a metal compound dispersion of the present invention is characterized by having a step of forming a metal compound powder by drying and / or firing the metal compound dispersion produced by the method for producing a metal compound dispersion of the present invention.

[0162] Specifically, among the metal compound powders, a method for producing a dry powder of a metal compound involves placing the metal compound dispersion produced by the method for producing a metal compound dispersion of the present invention described above in a static furnace and drying, for example, by vacuum drying or microwave drying, at a heating temperature of about 60°C to 200°C for 1 minute to 72 hours, thereby evaporating the water content of the metal compound dispersion of the present invention and obtaining a dry powder of the metal compound containing crystal particles of the metal compound contained in the metal compound dispersion of the present invention.

[0163] The heating temperature for drying the metal compound dispersion liquid produced by the method for producing a metal compound dispersion liquid of the present invention is preferably less than 100° C. The heating temperature is more preferably 90° C. or less. The heating time is preferably 1 hour or more and 100 hours or less, and more preferably 5 hours or more and 20 hours or less.

[0164] The heating temperature for drying the metal compound dispersion liquid produced by the method for producing a metal compound dispersion liquid of the present invention may be 100° C. or higher. The heating temperature is more preferably 110° C. or higher. The heating time is preferably 1 hour or longer and 100 hours or shorter, and more preferably 5 hours or longer and 20 hours or shorter.

[0165] Furthermore, the metal compound dispersion liquid produced by the method for producing a metal compound dispersion liquid of the present invention may be dried by vacuum drying without heating or by microwave drying. The heating time is preferably from 1 minute to 100 hours, more preferably from 1 hour to 100 hours, and even more preferably from 5 hours to 20 hours.

[0166] On the other hand, the method for producing a calcined powder of a metal compound includes vacuum drying and microwave drying the metal compound dispersion of the present invention as described above, placing the obtained dried powder of the metal compound in a static furnace, and calcining it in the atmosphere at a calcination temperature of 300°C or higher and 1,200°C or lower for a calcination time of 1 hour or higher and 72 hours or lower, thereby obtaining a calcined powder of the metal compound.

[0167] The metal compound powder may be prepared by pulverizing the dry powder and calcined powder of the metal compound described above. Furthermore, regardless of whether or not the powder is pulverized, the undersized particles (fine particles) obtained by classifying the dry powder and calcined powder of the metal compound described above using a sieve or the like may be used as the metal compound powder. The oversized particles (coarse particles) may be re-pulverized and classified for use. It is also possible to combine pulverization and classification using a vibrating sieve containing nylon- or fluororesin-coated iron balls or the like as grinding media. By combining classification and pulverization in this way, even if excessively large metal compound powder particles are present, they can be removed. Specifically, when classifying using a sieve, it is preferable to use one with a mesh size of 150 μm to 1,000 μm. A mesh size of 150 μm to 1,000 μm prevents the proportion of oversized particles from becoming too high, eliminating the need for repeated pulverization, and also prevents metal compound powder that requires pulverization from being classified as undersized particles.

[0168] The metal compound powder thus obtained can be mixed with water or an organic solvent as a dispersion medium and wet-pulverized using media such as beads to obtain a metal compound powder dispersion. Examples of organic solvents used as dispersion media include alcohol solvents, ketone solvents, ether solvents, ester solvents, aromatic hydrocarbon solvents, and aliphatic hydrocarbon solvents, and mixtures of these organic solvents with pure water are also possible. Examples of alcohol solvents that can be used include alcohols with 5 or fewer carbon atoms (methanol, ethanol, n-propanol, isopropyl alcohol, and butanol). Furthermore, to improve the film-forming properties of a metal compound film using the metal compound powder dispersion, a binder such as a resin component may be added. Examples of resin components used as binders include acrylic resins, polyurethanes, epoxy resins, polystyrene, polycarbonates, glycol-based resins, cellulose-based resins, and mixtures and copolymer resins thereof.

[0169] Furthermore, the method for producing a metal compound film containing a metal compound in a metal compound dispersion of the present invention is characterized by comprising a step of applying the metal compound dispersion produced by the method for producing a metal compound dispersion of the present invention onto a substrate, and drying and / or baking the applied coating to form a metal compound film on the substrate.

[0170] Specifically, among metal compound films, the method for producing a metal compound dry film includes a coating step of coating a metal compound dispersion onto the surface of a substrate, and a film drying step of drying the metal compound dispersion coated on the surface of the substrate to obtain a dry film.

[0171] The metal compound dispersion liquid produced by the above-described method for producing a metal compound dispersion liquid of the present invention is dropped onto the surface of a substrate using a syringe while, if necessary, filtering it through a filter having a pore size of 1 μm, for example, and applied by spin coating (700 rpm, 10 seconds, followed by 1500 rpm, 30 seconds). Next, the resulting mixture is dried at 110° C. for 30 minutes to form a metal compound dry film on the surface of the substrate.

[0172] On the other hand, among the metal compound films, a method for producing a calcined metal compound film includes a coating step of coating a metal compound dispersion onto the surface of a substrate, a film drying step of drying the metal compound dispersion coated on the surface of the substrate in the atmosphere, under vacuum, or under microwave irradiation 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 higher and 1,200°C or lower for a calcination time of 1 hour or higher and 12 hours or lower to obtain a calcined film.

[0173] As described above, the metal compound dispersion is applied to the surface of a substrate, and the substrate on which a dry metal compound film is formed by drying is placed in a static furnace and baked in the atmosphere at a baking temperature of 300°C or higher and 1,200°C or lower for a baking time of 1 hour or higher and 12 hours or lower, thereby forming a baked metal compound film on the surface of the substrate.

[0174] The metal carbide powder of the present invention is characterized by being a carbonized powder of the metal compound dispersion of the present invention. The metal carbide powder of the present invention is a powder of metal carbide obtained by carbonizing the metal compound in the metal compound dispersion of the present invention by firing the metal compound dispersion of the present invention.

[0175] The method for producing a metal carbide powder of the present invention is characterized by comprising the steps of drying a metal compound dispersion produced by the method for producing a metal compound dispersion of the present invention described above to obtain a metal compound powder, and calcining the metal compound powder to obtain a metal carbide powder.

[0176] First, the metal compound dispersion liquid produced by the above-described method for producing a metal compound dispersion liquid of the present invention is placed in a static furnace and dried, for example, by vacuum drying or microwave drying, at a heating temperature of about 60°C to 200°C for 1 minute to 72 hours, whereby the water content of the metal compound dispersion liquid of the present invention is evaporated and a metal compound powder containing crystal particles of the metal compound contained in the metal compound dispersion liquid of the present invention is obtained.

[0177] Next, the obtained metal compound powder is placed in a static furnace and fired in the atmosphere at a firing temperature of 1000°C or higher and 1900°C or lower for a firing time of 1 hour or higher and 12 hours or lower, thereby obtaining a metal carbide powder in which the metal compound powder is carbonized.

[0178] The obtained metal carbide powder may then be crushed using a ball mill, jet mill, cutter mill, or the like. The crushed metal carbide powder may be classified using a sieve or the like to obtain undersized particles (fine particle side), which may be used as the metal carbide powder of the present invention. The oversized particles (coarse particle side) may be subjected to another crushing step and classified before use. The sieve used for classification is preferably one with openings of 30 to 1000 μm.

[0179] The metal carbide powder (sample) of the present invention formed by the above-described method for producing a metal carbide powder of the present invention can be confirmed to be a carbide from the peaks in the X-ray diffraction pattern obtained by powder X-ray diffraction measurement under the following X-ray diffraction measurement conditions and X-ray diffraction analysis conditions.

[0180] = X-ray diffraction measurement conditions = Apparatus: MiniFlex II (manufactured by Rigaku Corporation) Measurement range (2θ): 5 to 90° Sampling width: 0.02° Scan speed: 2.0° / min X-ray: CuKα ray Voltage: 30 kV Current: 15 mA Divergence slit: 1.25° Scattering slit: 1.25° Receiving slit: 0.3 mm

[0181] = X-ray diffraction analysis conditions = · Data analysis software PDXL2 manufactured by Rigaku Corporation is used · Peaks are smoothed using b-spline to clarify peak tops.

[0182] The metal carbide film of the present invention is characterized by being a carbonized film of the metal compound dispersion of the present invention. The metal carbide film of the present invention is a metal carbide film formed by carbonizing the metal compound in the metal compound dispersion of the present invention by baking the metal compound dispersion of the present invention applied to a substrate.

[0183] The method for producing a metal carbide film of the present invention is characterized by comprising a step of applying a metal compound dispersion produced by the method for producing a metal compound dispersion of the present invention described above onto a substrate and firing the coating to form a metal carbide film on the substrate.

[0184] First, when applying the metal compound dispersion produced by the above-mentioned method for producing a metal compound dispersion of the present invention onto a substrate, it is preferable to adjust the solid content of the metal compound in the metal compound dispersion of the present invention so that the dispersion can be easily applied, and it is preferable to adjust the solid content so that it is 1 mass % or more and 70 mass % or less.

[0185] The solid content of the metal compound in the metal compound dispersion of the present invention is preferably adjusted according to the type and material of the substrate, and is more preferably 2% by mass or more and 65% by mass or less, even more preferably 4% by mass or more and 60% by mass or less, particularly preferably 5% by mass or more and 55% by mass or less, and even more particularly preferably 10% by mass or more and 50% by mass or less.

[0186] Furthermore, when the element species M in the metal compound dispersion liquid of the present invention is tantalum, the tantalum content in the metal compound dispersion liquid of the present invention may typically be 5 mass% or more and 30 mass% or less, 5 mass% or more and 25 mass% or less, 5 mass% or more and 20 mass% or less, 5 mass% or more and 15 mass% or less, or 5 mass% or more and 10 mass% or less.

[0187] Here, the tantalum content in the metal compound dispersion of the present invention is calculated by appropriately diluting the dispersion with dilute hydrochloric acid as needed, and measuring the Ta mass fraction in terms of Ta atoms using ICP optical emission spectrometry (AG-5110 manufactured by Agilent Technologies) in accordance with JIS K0116:2014.

[0188] Next, the metal compound dispersion of the present invention is applied to a substrate and fired to obtain a metal carbide film on the substrate, which contains metal carbides formed by carbonizing the metal compounds in the metal compound dispersion of the present invention. Examples of the substrate include crucibles, furnace materials, electrodes, fibers, filtration devices, filters, protective tubes, heater tubes, burner nozzles, and fire-resistant jigs. Examples of materials include carbon, metals, and ceramics, and examples of metals include metal carbides, metal oxides, and metal nitrides.

[0189] Specifically, the metal compound dispersion produced by the above-described method for producing a metal compound dispersion of the present invention is filtered, for example, through a filter with a pore size of 1 μm, and applied to the surface of a substrate using a brush or the like. The substrate to which the metal compound dispersion of the present invention has been applied is then placed in a static furnace and fired in the atmosphere at a firing temperature of 1000° C. or higher and 1900° C. or lower for a firing time of 1 hour to 12 hours, thereby forming a metal carbide film on the surface of the substrate. Note that, in addition to the method of applying the metal compound dispersion to the surface of the substrate using a brush or the like, other methods may also be used, such as spraying the metal compound dispersion onto the surface of the substrate or immersing the substrate in a container containing the metal compound dispersion of the present invention.

[0190] In this specification, when "X to Y" (X and Y are any numbers) is expressed, unless otherwise specified, it means "X or more and Y or less", and also means "preferably larger than X" or "preferably smaller than Y". Furthermore, when "X or more" (X is any number) or "Y or less" (Y is any number), it also means "preferably larger than X" or "preferably smaller than Y".

[0191] The metal compound dispersion of the present invention can reduce the content of highly hazardous chemical substances and increase the metal compound concentration. Furthermore, the method for producing the metal compound dispersion of the present invention does not involve the risk of bumping or the like during the production process, and facilitates mass production.

[0192] 1 is a table listing the physical property values ​​of the metal compound dispersions according to Examples 1 to 7 and Comparative Example 1. FIG. 2 is a table listing the measurement results of the metal compound dispersions according to Examples 1 to 7 and Comparative Example 1.

[0193] The metal compound dispersion liquid according to the embodiment of the present invention will be further described below with reference to the following Examples 1 to 7 and Comparative Example 1. However, the following examples do not limit the present invention.

[0194] (Example 1) In a 5 L beaker, Ta ２ O ５Approximately 660 mL of an aqueous solution of tantalum fluoride having a concentration of 80.0 g / L (0.24 mol in terms of Ta atoms) was added, and then 18.5 g (0.19 mol) of 35 mass % aqueous hydrogen peroxide was added, followed by stirring using a stirrer tip at room temperature for 10 minutes to obtain a mixture.

[0195] To the resulting mixture, approximately 490 g (7.2 mol) of 25% by mass aqueous ammonia was added to obtain a white precipitate. The resulting white precipitate was placed in a centrifuge tube and centrifuged at 4,500 rpm for 20 minutes. The supernatant was discarded, and only the white precipitate was collected.

[0196] Approximately 250 g of 5% by mass aqueous ammonia was added to the recovered white precipitate, mixed, and then centrifuged again at 4,500 rpm for 20 minutes, the supernatant was discarded, and only the white precipitate was recovered. This series of operations was repeated three times.

[0197] Thereafter, pure water was added to the white precipitate washed with 5% by mass ammonia water, and the total weight of the white precipitate and the pure water was adjusted to 215 g. Further, 35.0 g (0.182 mol) of citric acid was added and dissolved using ultrasound, thereby obtaining 250 g of a tantalic acid aqueous solution, which is the metal compound dispersion liquid according to Example 1.

[0198] In Example 2, pure water was added to the white precipitate washed with 5 mass % ammonia water used in Example 1, so that the total weight of the white precipitate and the pure water was 180 g. Thereafter, 70.0 g (0.777 mol) of lactic acid was added instead of 35.0 g of citric acid, and the mixture was dissolved using ultrasound, thereby obtaining 250 g of a tantalic acid aqueous solution, which was a metal compound dispersion liquid according to Example 2.

[0199] (Example 3) In a 100 mL beaker, Ta ２ O ５ Approximately 13.2 mL (0.0048 mol in terms of Ta atoms) of an aqueous solution of tantalum fluoride having a concentration of 80.0 g / L was added, and then 0.93 g (0.0096 mol) of 35 mass% aqueous hydrogen peroxide was added, followed by stirring using a stirrer tip at room temperature for 10 minutes to obtain a mixture.

[0200] To the resulting mixture, approximately 9.8 g (0.14 mol) of 25% by mass aqueous ammonia was added to obtain a white precipitate. The resulting white precipitate was placed in a centrifuge tube and centrifuged at 4,500 rpm for 20 minutes. The supernatant was discarded, and only the white precipitate was collected.

[0201] Approximately 250 g of 5% by mass aqueous ammonia was added to the recovered white precipitate, mixed, and then centrifuged again at 4,500 rpm for 20 minutes, the supernatant was discarded, and only the white precipitate was recovered. This series of operations was repeated three times.

[0202] Thereafter, pure water was added to the white precipitate washed with 5% by mass ammonia water, and the total weight of the white precipitate and the pure water was adjusted to 60.0 g. Further, 40.0 g of a 50% by mass gluconic acid solution was added and dissolved using ultrasound, thereby obtaining 100 g of a tantalic acid aqueous solution, which is the metal compound dispersion liquid according to Example 3.

[0203] In Example 4, pure water was added to the white precipitate washed with the 5% by mass aqueous ammonia used in Example 3, so that the total weight of the white precipitate and the pure water was 80.0 g. Thereafter, 20.0 g of DL-malic acid was added instead of 40.0 g of the 50% by mass gluconic acid solution, and the mixture was dissolved using ultrasound to obtain 100 g of a tantalic acid aqueous solution, which was a metal compound dispersion liquid according to Example 4.

[0204] In Example 5, pure water was added to the white precipitate washed with the 5% by mass aqueous ammonia used in Example 3, so that the total weight of the white precipitate and the pure water was 80.0 g. Thereafter, 20.0 g of lactobionic acid was added instead of 40.0 g of the 50% by mass gluconic acid solution, and the mixture was dissolved using ultrasound to obtain 100 g of a tantalic acid aqueous solution, which was a metal compound dispersion liquid according to Example 5.

[0205] (Example 6) In a 500 mL beaker, Nb ２ O ５ Approximately 105 mL (0.079 mol in terms of Nb atoms) of a 100.0 g / L niobium fluoride aqueous solution was added, and then 7.7 g (0.079 mol) of 35 mass% hydrogen peroxide water was added, followed by stirring using a stirrer tip at room temperature for 10 minutes to obtain a mixture.

[0206] To the resulting mixture, approximately 162 g (2.4 mol) of 25% by mass aqueous ammonia was added to obtain a white precipitate. The resulting white precipitate was placed in a centrifuge tube and centrifuged at 4,500 rpm for 20 minutes. The supernatant was discarded, and only the white precipitate was collected.

[0207] Approximately 250 g of 5% by mass aqueous ammonia was added to the recovered white precipitate, mixed, and then centrifuged again at 4,500 rpm for 20 minutes, the supernatant was discarded, and only the white precipitate was recovered. This series of operations was repeated three times.

[0208] Thereafter, pure water was added to the white precipitate washed with 5% by mass ammonia water, and the total weight of the white precipitate and the pure water was adjusted to 153.8 g. Further, 46.2 g (0.45 mol) of lactic acid was added and dissolved using ultrasound, thereby obtaining 200 g of a niobic acid aqueous solution, which is the metal compound dispersion liquid of Example 6.

[0209] Example 7: In a 300 mL beaker, HfO ２ Approximately 100 g (0.032 mol in terms of Hf atoms) of a 6.73 mass % aqueous hafnium fluoride solution was added, and then 6.2 g (0.064 mol) of a 35 mass % aqueous hydrogen peroxide solution was added, followed by stirring using a stirrer tip at room temperature for 10 minutes to obtain a mixture.

[0210] To the resulting mixture, approximately 65.3 g (0.96 mol) of 25% by mass aqueous ammonia was added to obtain a white precipitate. The resulting white precipitate was placed in a centrifuge tube and centrifuged at 4,500 rpm for 20 minutes. The supernatant was discarded, and only the white precipitate was collected.

[0211] Approximately 250 g of 5% by mass aqueous ammonia was added to the recovered white precipitate, mixed, and then centrifuged again at 4,500 rpm for 20 minutes, the supernatant was discarded, and only the white precipitate was recovered. This series of operations was repeated three times.

[0212] Thereafter, pure water was added to the white precipitate washed with 5% by mass ammonia water, and the total weight of the white precipitate and pure water was adjusted to 204.4 g. Further, 19.6 g (0.19 mol) of lactic acid was added and dissolved using ultrasound, thereby obtaining 224 g of a hafnic acid aqueous solution, which is the metal compound dispersion liquid of Example 7.

[0213] (Comparative Example 1) A container was ２ O ５ Tantalum chloride of 25.0 g / L (0.075 mol in terms of Ta atoms) was dissolved in a small amount of methanol, and pure water was added to obtain an aqueous solution of tantalum chloride. Ta tantalate was obtained by adding 25 mass % ammonia water to the aqueous solution of tantalum chloride. ２ O ５ ・nH ２ A precipitate consisting of Ta was obtained. The precipitate was washed with water to completely remove chloride ions from the precipitate. Pure water, 54 g (0.6 mol) of lactic acid, which was 8 times the molar amount of Ta, 46 g (0.68 mol) of 25% by mass ammonia water, and 109 g (1.12 mol) of 35% by mass hydrogen peroxide water were added to the precipitate from which the chloride ions had been completely removed, and dissolved to obtain 257.4 g of a tantalic acid aqueous solution, which was the metal compound dispersion liquid according to Comparative Example 1.

[0214] The following physical properties were measured for the metal compound dispersions according to Examples 1 to 7 and Comparative Example 1. The measured physical properties and the methods for measuring the physical properties are shown below, and the measurement results are shown in FIGS. 1 and 2.

[0215] <Elemental Analysis> If necessary, the sample was appropriately diluted with hydrofluoric acid and nitric acid, and the Ta mass fraction in terms of Ta atoms, the Nb mass fraction in terms of Nb atoms, and the Hf mass fraction in terms of Hf atoms were measured using high-frequency inductively coupled plasma spectrometry (ICP optical emission spectrometry (Agilent Technologies: Agilent 5110)) in accordance with JIS K0116:2014.

[0216] <Measurement of Fluorine Content> Distillation was carried out based on the lanthanum alizarin complexone absorptiometry specified in JIS K0102:2014, and the fluorine content was measured using the obtained absorptiometer.

[0217] <Measurement of hydrogen peroxide content> Titanium sulfate solution and sulfuric acid were added to the sample. At this time, sulfuric acid was added so that the concentration was 2 mol / L. Then, the hydrogen peroxide content was measured using an absorptiometer at a wavelength of 410 mm.

[0218] <Measurement of Ammonia Content> Sodium hydroxide was added to the sample to make it strongly basic. The solution was distilled and the ammonia content was measured using an ammonium ion electrode.

[0219] <Measurement of organic acid content> 70 μL of sample solution and 3-(trimethylsilyl)-1-propane-1,1,2,2,3,3-d in heavy water were ６ -sodium sulfonate (hereinafter referred to as DSS-d ６ DSS-d ６ A measurement sample was prepared by mixing 70 μL of heavy water solution and 560 μL of heavy water. １ According to the H-NMR spectrum measurement conditions, １ The organic acid content was measured by measuring the H-NMR spectrum.

[0220] <Particle Size Distribution Measurement (Dynamic Light Scattering)> The particle size distribution was evaluated by dynamic light scattering in accordance with JIS Z 8828:2019 using a zeta potential, particle size, and molecular weight measurement system (ELSZ-2000, manufactured by Otsuka Electronics Co., Ltd.). Furthermore, immediately before the measurement, the metal compound dispersions of Examples 1 to 7 and Comparative Example 1, which were the measurement targets, were filtered through a filter with a 1 μm pore size to remove dust and other particles. Furthermore, D50 indicates the particle size at which the volume fraction reaches 50%. "Initial" in FIG. 2 refers to the metal compound dispersions of Examples 1 to 7 immediately after production. Furthermore, "2 weeks later" and "3 weeks later" in FIG. 2 refer to the metal compound dispersions of Examples 1 to 7 that were left to stand for 2 weeks or 3 weeks from the day of production in an incubator set at room temperature of 25°C. In addition, since the metal compound dispersion liquid according to Comparative Example 1 contained precipitates, the particle diameter (D50) could not be measured.

[0221] <Light Transmittance Measurement> 3 ml of the metal compound dispersion liquid according to Examples 1 to 7 was placed in a glass cell, and the light transmittance in the wavelength range of 400 nm to 800 nm (specifically, the light transmittance at wavelengths of 400 nm, 500 nm, 600 nm, 700 nm, and 800 nm) of the metal compound dispersion liquid according to Examples 1 to 7 was measured using a spectrophotometer under the light transmittance measurement conditions described above. A light transmittance of more than 100% was considered to be 100%. "Initial" in FIG. 2 refers to the metal compound dispersion liquid according to Examples 1 to 7 immediately after production. Furthermore, "2 weeks later" and "3 weeks later" in FIG. 2 refer to the metal compound dispersion liquid according to Examples 1 to 7 after it had been left standing for 2 weeks or 3 weeks from the day of production in an incubator set at room temperature of 25°C. The light transmittance of the metal compound dispersion liquid according to Comparative Example 1 could not be measured due to the presence of precipitates.

[0222] <pH Measurement> The pH of the metal compound dispersions according to Examples 1 to 7 was measured using an electrode (Standard ToupH electrode 9615S-10D, manufactured by HORIBA) of a pH meter (Glass electrode type hydrogen ion concentration indicator D-51, manufactured by HORIBA) after confirming that the liquid temperature had stabilized at 25°C. "Initial" in FIG. 2 refers to the metal compound dispersions according to Examples 1 to 7 immediately after production. Furthermore, "2 weeks later" and "3 weeks later" in FIG. 2 refer to the metal compound dispersions according to Examples 1 to 7 after being allowed to stand for 2 weeks or 3 weeks from the day of production in an incubator set at room temperature of 25°C. Note that the pH of the metal compound dispersion according to Comparative Example 1 was not measured because a precipitate had formed.

[0223] As shown in FIGS. 1 and 2 , the metal compound dispersions according to Examples 1 to 7 were metal compound dispersions containing a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid. The particle size (D50) of the particles in the metal compound dispersions was 900 nm or less as determined by particle size distribution measurement using a dynamic light scattering method, and thus the metal compound dispersions were excellent in stability and dispersibility.

[0224] The metal compound dispersions according to Examples 1 to 7 were metal compound dispersions containing a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid. The metal compound dispersions had a maximum light transmittance of 80% T or more in the wavelength range of 400 nm or more and 800 nm or less, and therefore had excellent stability and dispersibility.

[0225] The metal compound dispersions according to Examples 1 to 7 were metal compound dispersions containing a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid. The particle size (D50) of the particles in the metal compound dispersions, as measured by particle size distribution using a dynamic light scattering method, was 900 nm or less, and the maximum light transmittance of the metal compound dispersions in the wavelength range of 400 nm to 800 nm was 80% T or more, and therefore the metal compound dispersions were excellent in stability and dispersibility.

[0226] The metal compound dispersion liquids according to Examples 1 to 7 were able to achieve a high concentration of element species M by having the content of element species M in the metal compound dispersion liquid be 0.01 mass % or more and 25 mass % or less in terms of atoms of element species M.

[0227] The metal compound dispersions according to Examples 1 to 7 had a pH of 2.0 or more and 10.0 or less, and therefore the polyacid ions contained in the dispersions were stable.

[0228] In the metal compound dispersions according to Examples 1 to 7, the molar ratio (alkaline compound / m) of the alkaline compound to the element species M(m) was greater than 0 and less than 10, and therefore the content of the alkaline compound was extremely small.

[0229] The metal compound dispersion liquids according to Examples 1 to 7 were prepared by dissolving the hydrogen peroxide (H ２ O ２ ) and the element species M(m) (H ２ O ２ / m) was greater than 0 to 1, the content of hydrogen peroxide was extremely small.

[0230] In the metal compound dispersions according to Examples 1 to 7, the molar ratio (organic acid / m) of the organic acid to the element species M(m) was greater than 0 and less than 50, and therefore it was confirmed that the organic acid was contained.

[0231] The metal compound dispersions according to Examples 1 to 7 further contained fluorine (F), and the molar ratio (F / m) of the fluorine (F) to the element species M(m) was 0.5 or less, and therefore the fluorine content was extremely small.

[0232] The inventions disclosed in this specification include, in addition to the configurations of each invention and embodiment, those specified by changing these partial configurations to other configurations disclosed in this specification, to the extent applicable, or those specified by adding other configurations disclosed in this specification to these configurations, or those specified as higher-level concepts specified by deleting these partial configurations to the extent that partial effects can be obtained.

[0233] The metal compound dispersion according to the present invention reduces the content of highly hazardous chemical substances and achieves a high concentration of metal compounds. Furthermore, the metal compound dispersion according to the present invention has excellent storage stability and reduces the rate of defective products caused by sedimentation over time, thereby reducing waste and the energy costs associated with waste disposal. These advantages contribute to the sustainable management and efficient use of natural resources, as well as the achievement of decarbonization (carbon neutrality).

Claims

1. A metal compound dispersion liquid comprising a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid, wherein the particle diameter (D50) of particles in the metal compound dispersion liquid is 900 nm or less as determined by particle size distribution measurement using dynamic light scattering.

2. A metal compound dispersion liquid comprising a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid, wherein the maximum light transmittance of the metal compound dispersion liquid in the wavelength range of 400 nm to 800 nm is 80%T or more.

3. A metal compound dispersion liquid containing a metal compound of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si, and an organic acid, wherein the particle diameter (D50) of particles in the metal compound dispersion liquid is 900 nm or less as determined by particle size distribution measurement using dynamic light scattering, and the maximum light transmittance of the metal compound dispersion liquid in the wavelength range of 400 nm to 800 nm is 80%T or more.

4. The metal compound dispersion liquid according to any one of claims 1 to 3, further comprising an alkaline compound.

5. A metal compound dispersion liquid described in any one of claims 1 to 3, characterized in that the content of element species M in the metal compound dispersion liquid is 0.01 mass % or more and 25 mass % or less in terms of atoms of element species M.

6. The metal compound dispersion liquid according to any one of claims 1 to 3, further comprising a metal compound of one or more element species X selected from the group consisting of alkali metals, alkaline earth metals, Cu, Zn, Ag, Sn, Fe, and lanthanoids.

7. The metal compound dispersion liquid according to any one of claims 1 to 3, further comprising hydrogen peroxide.

8. The metal compound dispersion liquid according to any one of claims 1 to 3, characterized in that the organic acid is citric acid, tartaric acid, lactic acid, malic acid, gluconic acid, or lactobionic acid.

9. The metal compound dispersion liquid according to any one of claims 1 to 3, characterized in that the pH of the metal compound dispersion liquid is 2.0 or more and 10.0 or less.

10. The metal compound dispersion liquid according to claim 4, characterized in that the molar ratio of the alkaline compound to the element species M(m) (alkaline compound / m) is greater than 0 and up to 10.

11. The hydrogen peroxide (H ２ O ２ ) and the element species M(m) (H ２ O ２ 8. The metal compound dispersion liquid according to claim 7, wherein m is greater than 0 and less than 1.

12. The metal compound dispersion liquid according to any one of claims 1 to 3, characterized in that the molar ratio (organic acid / m) of the organic acid to the element species M(m) is greater than 0 and in the range of 50 to 50.

13. The metal compound dispersion liquid according to any one of claims 1 to 3, further comprising fluorine (F), the content of the fluorine (F) being greater than 0 mass% and not more than 0.1 mass% in terms of fluorine atoms, and the molar ratio (F / m) of the fluorine (F) to the element species M(m) being 0.5 or less.

14. The metal compound dispersion liquid according to any one of claims 1 to 3, further comprising chlorine (Cl), wherein the content of the chlorine (Cl) is greater than 0 mass % and 0.1 mass % or less in terms of chlorine atoms, and the molar ratio (Cl / m) of the chlorine (Cl) to the element species M(m) is 0.2 or less.

15. A method for producing a metal compound dispersion liquid, comprising the steps of: mixing and stirring a halide of one or more element species M selected from the group consisting of Ta, Nb, Mo, W, Ti, Zr, Hf, and Si with hydrogen peroxide to obtain a mixture; reacting the mixture with an alkaline compound and recovering the resulting precipitate by solid-liquid separation; washing the recovered precipitate with the alkaline compound; and adding pure water and an organic acid to the washed precipitate to dissolve it.

16. The method for producing a metal compound dispersion liquid according to claim 15, wherein the halide is a fluoride and / or a chloride.

17. A metal compound film, characterized in that it is a coating film of the metal compound dispersion liquid according to any one of claims 1 to 3.

18. A method for producing a metal compound film, comprising the step of applying a metal compound dispersion produced by the method for producing a metal compound dispersion described in claim 15 onto a substrate, and drying and / or baking the applied dispersion to form a metal compound film on the substrate.

19. A metal carbide powder characterized by being a carbonized powder of the metal compound dispersion liquid according to any one of claims 1 to 3.

20. A method for producing a metal carbide powder, comprising the steps of: drying a metal compound dispersion produced by the method for producing a metal compound dispersion described in claim 15 to obtain a metal compound powder; and calcining the metal compound powder to obtain a metal carbide powder.

21. A metal carbide film, characterized in that it is a carbonized film of the metal compound dispersion liquid according to any one of claims 1 to 3.

22. A method for producing a metal carbide film, comprising the step of applying a metal compound dispersion produced by the method for producing a metal compound dispersion described in claim 15 onto a substrate and firing the substrate to form a metal carbide film on the substrate.

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