Tantalic acid dispersion and tantalic acid compound

Abstract

A novel tantalic acid dispersion that does not contain non-volatile organic components and has high dispersibility in water is provided. The tantalic acid dispersion is characterized in that it contains tantalum and / or tantalic acid and an amine in water, and when powder obtained by drying the tantalic acid dispersion is subjected to powder X-ray diffraction using CuKα rays, the intensity ratio (5.5° / 29°) of the intensity at 2θ = 5.5° to the intensity at 2θ = 29° in the X-ray diffraction pattern is 1.00 or higher.

Description

Technical Field

[0001] This invention relates to tantalic acid dispersions containing tantalum and / or tantalic acid in water, and tantalic acid compounds. Background Technology

[0002] Despite its chemical resistance comparable to precious metals and its body-centered cubic crystal structure, tantalum is easily processed even at temperatures below room temperature, making it a material used in a variety of industrial applications. For example, tantalum-containing materials are used in heat exchangers in chemical equipment, charge carriers in high-temperature industrial furnaces, medical implants, and capacitors in electronic components.

[0003] In addition, tantalum oxide has attracted attention in recent years as a material for optoelectronics, catalysts, etc.

[0004] For example, Patent Document 1 discloses a particle size composed of oxalic acid and tantalum oxide in a (HCOO)2 / Ta2O5 molar ratio ranging from 0.5 to 5. The following describes a tantalum oxide sol, and discloses a method for manufacturing the tantalum oxide sol, characterized in that oxalic acid is added to an active tantalum hydroxide compound in a molar ratio of (HCOO)2 / Ta2O5 ranging from 5.0 to 30, and the reaction is carried out at a temperature of 90°C or above for more than 2 hours.

[0005] In addition, Patent Document 2 discloses a tantalum oxide sol containing at least one hydroxycarboxylic acid selected from citric acid, tartaric acid and malic acid in a hydroxycarboxylic acid / Ta2O5 (molar ratio) range of 0.05 to 10, and discloses a method for manufacturing tantalum oxide sol, characterized in that a hydrofluoric acid solution of tantalum is reacted with an alkaline solution in the presence of at least one hydroxycarboxylic acid selected from citric acid, tartaric acid and malic acid.

[0006] Patent document 3 discloses a method for manufacturing an organic tantalum aqueous solution, characterized in that TaCl5 is dissolved in a small amount of methanol, water is added, and an ammonia solution is added to form a precipitate of tantalic acid Ta2O5·nH2O. The precipitate is washed with water to completely remove chloride ions. Then, water, hydroxycarboxylic acid or EDTA (ethylenediaminetetraacetic acid), and then amine (ammonia or guanidine carbonate) and hydrogen peroxide water are added for dissolution.

[0007] Patent document 4 does not disclose tantalate compound itself, but discloses a method for manufacturing a photocatalyst film. The method is characterized by mixing a solution or dispersion of a tetravalent titanium compound, a solution or dispersion of a pentavalent tantalum compound, and a water-soluble reducing agent, heating the mixture to a temperature of 100-250°C to obtain titanium oxide powder, pulverizing the titanium oxide powder into particles with an average particle size of less than 100 nm and dispersing them in a solvent to obtain a dispersion, coating the dispersion onto a substrate, drying the dispersion, and forming a film. In this process, a titanium oxide containing tantalum oxide is obtained as an intermediate substance.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 08-143315

[0011] Patent Document 2: Japanese Patent Application Publication No. 2006-117460

[0012] Patent Document 3: Japanese Patent Application Publication No. 2006-182714

[0013] Patent Document 4: Japanese Patent Application Publication No. 2010-188226 Summary of the Invention

[0014] The problem the invention aims to solve

[0015] If an industrially available dispersion of tantalic acid containing tantalum and / or tantalic acid, particularly a dispersion of tantalum and / or tantalic acid hydrates and / or their ions dispersed in water, could be expected to be applied to the surface of various components to form a chemically resistant surface layer, or used as an additive to a catalyst, or reacted with alkali metals to be used industrially as an alkali metal tantalum salt, thus effectively serving various industrial applications.

[0016] However, as disclosed in the aforementioned patent documents 1 to 3, tantalum oxide sol and organic tantalum aqueous solution, most of the previously known tantalum acid dispersions contain organic components that are difficult to volatilize, such as hydroxycarboxylic acid, oxalic acid, and EDTA (ethylenediaminetetraacetic acid). Therefore, these organic components may sometimes become obstacles during film formation, or hinder catalytic activity when used as additives for catalysts, or become obstacles in industrial applications.

[0017] Furthermore, if highly reactive tantalate compounds can be industrially available, they can be expected to be used as additives to catalysts or reacted with alkali metal compounds to be utilized industrially as alkali metal tantalates, thus effectively serving various industrial applications.

[0018] However, the tantalate compounds disclosed in Patent Document 4 have the problem of insufficient reactivity with alkali metal compounds.

[0019] Therefore, the object of the present invention is to provide a novel tantalic acid dispersion that does not contain non-volatile organic components such as hydroxycarboxylic acid, oxalic acid, and EDTA, has high dispersibility in water, and a method for manufacturing the same, as well as a novel tantalic acid compound with high reactivity with alkali metal compounds.

[0020] Solution for solving the problem

[0021] The present invention provides a tantalic acid dispersion, characterized in that the tantalic acid dispersion contains tantalum and / or tantalic acid in water and contains amine, and when the powder obtained by drying the tantalic acid dispersion is subjected to powder X-ray diffraction using CuKα rays, the intensity ratio (5.5° / 29°) of the intensity at 2θ = 5.5° to the intensity at 2θ = 29° in the X-ray diffraction pattern is greater than 1.00.

[0022] In addition, the present invention also proposes a method for manufacturing a tantalic acid dispersion, characterized in that a tantalum salt solution is added to an aqueous amine solution to obtain a primary reaction solution, the primary reaction solution is added to ammonia water to obtain a secondary reaction solution, the tantalum-containing precipitate generated in the secondary reaction solution is washed, and the washed tantalum-containing precipitate, amine and water are mixed to produce a tantalic acid dispersion.

[0023] In addition, the present invention also proposes a tantalate compound, characterized in that, when powder X-ray diffraction is performed using CuKα rays, the intensity ratio (5.5° / 29°) of the intensity at 2θ = 5.5° to the intensity at 2θ = 29° in the X-ray diffraction pattern is 0.90 or higher.

[0024] The effects of the invention

[0025] The tantalic acid dispersion proposed in this invention has the following characteristics: it does not contain non-volatile organic components such as hydroxycarboxylic acids, oxalic acid, and EDTA, and it exhibits high dispersibility in water. In particular, by increasing the amine content, its dispersibility in water can be further improved, resulting in an aqueous solution with extremely high transmittance. Therefore, the tantalic acid dispersion proposed in this invention can be coated onto the surface of various components to form a surface layer with specified functions such as chemical resistance, or used as an additive in catalysts, thus effectively serving various industrial applications. Furthermore, the tantalic acid dispersion proposed in this invention exhibits high reactivity with alkali metal salts, such as sodium hydroxide and potassium hydroxide. Even without reacting under high temperature and pressure conditions using an autoclave or similar equipment, alkali metal tantalates can be easily obtained simply by mixing and reacting with alkali metal salts, such as sodium hydroxide and potassium hydroxide.

[0026] The tantalate compounds proposed in this invention have high reactivity with alkali metal compounds, such as sodium hydroxide and potassium hydroxide. For example, even without using an autoclave or other high-temperature and high-pressure conditions for reaction, alkali metal tantalates can be easily obtained simply by mixing and reacting with alkali metal compounds, such as sodium hydroxide and potassium hydroxide, in a liquid. Attached Figure Description

[0027] Figure 1 The XRD pattern of the precipitate obtained by reacting the tantalic acid dispersion (sample) obtained in Example 1 with NaOH.

[0028] Figure 2 The XRD pattern of the precipitate obtained by conducting a reactivity test with NaOH using the tantalic acid-containing liquid (sample) obtained in Comparative Example 2.

[0029] Figure 3 The XRD pattern of the precipitate obtained by reacting the tantalic acid dispersion (sample) obtained in Example 1 with KOH.

[0030] Figure 4 The X-ray diffraction pattern obtained by performing powder X-ray diffraction on the powder obtained by drying the tantalic acid dispersion (sample) obtained in Example 1.

[0031] Figure 5 The X-ray diffraction pattern obtained by performing powder X-ray diffraction on the powder obtained by drying the tantalic acid dispersion (sample) obtained in Example 2.

[0032] Figure 6 The X-ray diffraction pattern obtained by performing powder X-ray diffraction on the powder obtained by drying the tantalic acid dispersion (sample) obtained in Example 3.

[0033] Figure 7 The X-ray diffraction pattern obtained by performing powder X-ray diffraction on the powder obtained by drying the tantalic acid dispersion (sample) obtained in Example 4.

[0034] Figure 8 The X-ray diffraction pattern obtained by performing powder X-ray diffraction on the powder obtained by drying the tantalic acid dispersion (sample) obtained in Example 5.

[0035] Figure 9 The X-ray diffraction pattern obtained by performing powder X-ray diffraction on the powder obtained by drying the tantalic acid dispersion (sample) obtained in Example 6.

[0036] Figure 10The X-ray diffraction pattern obtained by performing powder X-ray diffraction on the powder obtained by drying the tantalic acid-containing liquid (sample) obtained in Comparative Example 1.

[0037] Figure 11 The X-ray diffraction pattern obtained by performing powder X-ray diffraction on the powder obtained by drying the tantalic acid-containing liquid (sample) obtained in Comparative Example 2. Detailed Implementation

[0038] Next, the present invention will be described based on exemplary embodiments. However, the present invention is not limited to the embodiments described below.

[0039] <This Tantalic Acid Dispersion>

[0040] An example of the tantalic acid dispersion (“this tantalic acid dispersion”) of the present invention is a tantalic acid dispersion containing tantalum and / or tantalic acid and an amine in water.

[0041] In this invention, "tantalic acid dispersion" refers to a liquid in which substances derived from tantalum and / or tantalic acid are dispersed in water in a non-precipitated state, or a liquid in which tantalum and / or tantalic acid are dissolved in water to form an aqueous solution.

[0042] For example, if no precipitation is observed visually after standing at room temperature for more than 24 hours, it can be concluded that the substances derived from tantalum and / or tantalic acid are dispersed in water in a non-precipitated state.

[0043] The state of this tantalic acid dispersion includes not only liquid states such as water, but also paste states, suspension states (sols), etc.

[0044] The presence of tantalum and / or tantalum acid in this tantalic acid dispersion in water can be confirmed by methods such as ICP emission spectroscopy (inductively coupled plasma atomic emission spectrometry).

[0045] In addition, the presence of amines in this tantalic acid dispersion in water can be confirmed by GC-MS or similar methods.

[0046] It should be noted that the state in which tantalum and / or tantalum acid exists in water within this tantalum acid dispersion is still under investigation. While technical proof is not possible, it can be presumed that tantalum and / or tantalum acid exist in this tantalum acid dispersion as hydrates and / or ionic forms. In particular, based on the characteristics of the XRD pattern described later, it can be presumed that tantalum and / or tantalum acid exist in water as ionic forms of polyacid structures formed by ionic bonding with amines.

[0047] This tantalic acid dispersion preferably contains 0.1 to 40% by mass of tantalum, calculated as Ta2O5, and more preferably 0.5% by mass or more, especially 1% by mass or more. On the other hand, it is even more preferably 30% by mass or less, especially 20% by mass or less.

[0048] It should be noted that tantalum and / or tantalum acid in this tantalic acid dispersion may not exist in the Ta2O5 state. In this invention, the use of Ta2O5 conversion to represent the tantalum content in this tantalic acid dispersion is based on the convention in the art for expressing Ta concentration.

[0049] This tantalic acid dispersion preferably contains 0.01 to 30% by mass of amine.

[0050] A higher amount of amine can improve the dispersibility and / or solubility of tantalum and / or tantalic acid relative to water. Although it cannot be technically proven, it can be speculated that ionic bonding between the amine and tantalic acid can improve solubility relative to water. From this point of view, the tantalic acid dispersion preferably contains 0.01% by mass or more of amine, more preferably 0.1% by mass or more, and particularly 0.5% by mass or more.

[0051] On the other hand, if the amount of amine is too large, it may cause adverse effects such as hindering film formation or impeding catalysis. Therefore, this tantalic acid dispersion preferably contains amine at a proportion of 30% by mass or less, more preferably at a proportion of 25% by mass or less, and especially at a proportion of 20% by mass or less.

[0052] At this point, for example, by setting the concentration of amine in the tantalic acid dispersion, which has a tantalic oxide concentration of 9% by mass, to 5% by mass or more, tantalum and / or tantalic acid are dissolved in water, thereby making a dispersion with extremely high transmittance, i.e., an aqueous solution with a transmittance of 40% or more at 400 nm, and more preferably 50% or more.

[0053] It should be noted that this tantalic acid dispersion preferably contains 55 to 100 parts by mass of amine relative to 100 parts by mass of tantalum (converted to Ta2O5). By containing amine in this proportion, tantalum and / or tantalic acid can be dissolved in water, thereby producing a dispersion with extremely high transmittance, i.e., an aqueous solution with a transmittance of 400 nm or more, and more preferably 50% or more.

[0054] In this invention, a dispersion with a transmittance of 40% or more at 400 nm is referred to as an aqueous solution.

[0055] Alkylamines are preferably examples of amines contained in this tantalic acid dispersion.

[0056] As the aforementioned alkylamine, an alkylamine having 1 to 3 alkyl groups is preferred. In the case of 2 to 3 alkyl groups, all three alkyl groups may be identical; alternatively, different alkyl groups may be included. From a solubility point of view, the alkyl group of the alkylamine preferably has 1 to 6 carbon atoms, preferably 4 or less, especially 3 or less, and even more especially 2 or less.

[0057] Specific examples of the aforementioned alkylamines include methylamine, dimethylamine, trimethylamine, ethylamine, methyl ethylamine, diethylamine, triethylamine, methyl diethylamine, dimethyl ethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, isopropylamine, diisopropylamine, triisopropylamine, n-butylamine, di-n-butylamine, tri-n-butylamine, isobutylamine, diisobutylamine, triisobutylamine, tert-butylamine, n-pentylamine, n-hexylamine, etc.

[0058] Among them, methylamine, dimethylamine, trimethylamine, ethylamine, methyl ethylamine, diethylamine, triethylamine, methyl diethylamine and dimethyl ethylamine are preferred, and methylamine, dimethylamine and trimethylamine are even more preferred.

[0059] Preferably, in the X-ray diffraction pattern obtained by powder X-ray diffraction of the dried powder using CuKα rays, the intensity ratio (5.5° / 29°) of the intensity at 2θ = 5.5° to the intensity at 2θ = 29° is 1.00 or higher.

[0060] It was confirmed that a larger intensity ratio (5.5° / 29°) between the intensity at 2θ = 5.5° and the intensity at 2θ = 29° indicates higher dispersibility and transmittance of the tantalic acid dispersion. Furthermore, it was confirmed that high intensity peaks appearing at angles lower than 2θ = 15° in the X-ray diffraction pattern are characteristic of polyacid structures. Therefore, it can be inferred that a higher intensity ratio (5.5° / 29°) indicates a higher proportion of polyacid structures, resulting in higher dispersibility and transmittance of the tantalic acid dispersion.

[0061] From this perspective, the strength ratio (5.5° / 29°) of this tantalic acid dispersion is preferably 1.00 or higher, more preferably 1.01 or higher, particularly 1.02 or higher, particularly 1.03 or higher, particularly 1.06 or higher, and particularly 1.10 or higher. It should be noted that the upper limit is expected to be around 2.00.

[0062] It should be noted that the aforementioned intensities of 2θ = 29° and 2θ = 5.5° are not the intensities at the peak positions near these angles, but rather specify the intensities at these angles.

[0063] The structure of the aforementioned polyacid can be deduced to be: [TaxOy] n-The structure shown is ·mH₂O (6≤x≤10, 19≤y≤28, n=8, m is an integer from 0 to 50). Specifically, as a polyacid structure, ions with [Ta₆O₂]₂O₂ can be listed. 19 ] 8- Hydrous compounds with the structure shown in ·mH2O, etc. However, it is not limited to this type of hydrous compound.

[0064] In addition to the features in the X-ray diffraction pattern, the following aspects can be cited as the basis for this conjecture: high reactivity with alkali metal compounds, and the ability to produce compounds with polyacid structures when mixed and reacted with NaOH, LiOH or KOH.

[0065] (Other ingredients)

[0066] This tantalic acid dispersion can be composed of water that does not contain any components other than tantalum and / or tantalic acid hydrates and / or their ions, and amines.

[0067] On the other hand, this tantalic acid dispersion may contain components other than tantalum and / or tantalic acid and amines (referred to as "other components") within a range that does not hinder its effectiveness. For example, it may contain additives such as ammonia, inorganic dispersants, and pH adjusters as such other components. However, it is not limited to these. In this case, the content of such other components in the tantalic acid dispersion is preferably less than 5% by mass, more preferably less than 4% by mass, and especially less than 3% by mass.

[0068] Furthermore, it is assumed that this tantalic acid dispersion contains unavoidable impurities, but this is not intentional. In this case, the content of unavoidable impurities is preferably less than 0.01% by mass.

[0069] It should be noted that one of the characteristics of this tantalic acid dispersion is that it does not contain non-volatile organic compounds. If this tantalic acid dispersion does not contain non-volatile organic compounds, it can not only be used for film formation by drying at relatively low temperatures (below 100°C), but also, due to its lack of impurities, can be effectively used for various applications such as catalyst feedstock.

[0070] It should be noted that, in this invention, "non-volatile organic compounds" refers to organic compounds such as hydroxycarboxylic acids, oxalic acid, and EDTA, which have a volatilization temperature of 110°C or higher.

[0071] Regarding the statement that this tantalic acid dispersion "does not contain non-volatile organic components," in addition to confirming it through the manufacturing method, if the manufacturing method is unknown, it can also be confirmed by analyzing the presence or absence of non-volatile organic components using methods such as gas chromatography, nuclear magnetic resonance (NMR), and GC-MS.

[0072] At this point, the statement that this tantalic acid dispersion "does not contain non-volatile organic components" refers to the case where the content of organic matter at an evaporation temperature above 110°C is less than 1%.

[0073] (transmittance)

[0074] This tantalic acid dispersion can achieve a transmittance of 40% or higher, then 50% or higher, then 60% or higher, and then 70% or higher at 400 nm.

[0075] This tantalic acid dispersion can improve the transmittance at 400 nm by increasing the amine content.

[0076] (Reactivity with alkali metal compounds)

[0077] This tantalic acid dispersion can produce alkali metal tantalum salts simply by reacting with alkali metal compounds such as sodium hydroxide and potassium hydroxide, without heating to above 80°C.

[0078] For example, in 30g of a tantalic acid dispersion (25°C) adjusted to contain 9% tantalum by mass (Ta₂O₅), 30mL of a 2.2% tantalum hydroxide aqueous solution (25°C) was added while stirring. After stirring for 15 minutes, a reaction solution was obtained. When the precipitate obtained by adding 100mL of ethanol to this reaction solution was dried, Na₂Ta₆O₅ was obtained. 19 Powder containing 15H2O.

[0079] Therefore, this tantalic acid dispersion exhibits high reactivity with alkali metal salts, and as described above, when it reacts with an aqueous sodium hydroxide solution, it produces Na₂Ta₆O. 19 ·Precipitation of 15H2O.

[0080] Alternatively, for example, while stirring, 30g of a tantalic acid dispersion (25°C) containing 9% tantalum by mass (calculated as Ta2O5) was added to the mixture.

[0081] After adding 30 mL of ethanol, the mixture was stirred for 15 minutes to obtain a reaction solution. When the precipitate obtained by adding 100 mL of ethanol to this reaction solution was dried, it yielded a product containing K8Ta6O. 19 Powder containing ·16H2O.

[0082] Therefore, this tantalic acid dispersion exhibits high reactivity with alkali metal salts, and as described above, when reacting with potassium hydroxide aqueous solution, it generates K8Ta6O. 19 ·Precipitation of 16H2O.

[0083] Typically, in order to obtain, for example, Na8Ta6O 19·15H2O, K8Ta6O 19 Tantalates of alkali metals such as ·16H2O are difficult to prepare simply by mixing tantalum hydroxide with aqueous solutions of sodium hydroxide or potassium hydroxide and reacting them under high temperature and pressure conditions in an autoclave, requiring heating to at least 80°C. However, this tantalum acid dispersion has high reactivity with alkali metal salts, so tantalum acid hydrate (Na8Ta6O) can be obtained simply by mixing and reacting with aqueous solutions of sodium hydroxide or potassium hydroxide and then cooling. 19 ·15H2O, K8Ta6O 19 ·16H2O).

[0084] It should be noted that the precipitate formed is Na8Ta6O. 19 ·15H2O or K8Ta6O 19 The precipitation of 16H2O can be confirmed, for example, by identification based on X-ray diffraction (XRD). However, it is not limited to this method.

[0085] That is, under the following conditions, the aforementioned precipitate is measured by X-ray diffraction and compared with the XRD pattern of ICDD card No. 00-024-1145 to identify whether it is Na8Ta6O. 19 • 15H2O. Additionally, comparing the XRD pattern with that of ICDD card No. 01-073-8508 allows for identification of whether it is K8Ta6O. 19 ·16H2O.

[0086] <Method for manufacturing this dispersion>

[0087] Next, a suitable manufacturing method for this tantalic acid dispersion (referred to as "this dispersion manufacturing method") will be described.

[0088] As an example of this dispersion manufacturing method, a method for manufacturing a tantalic acid dispersion can be described as follows: characterized in that a tantalum salt solution is added to an aqueous amine solution to obtain a primary reaction solution (this process is referred to as the "primary neutralization step"), the primary reaction solution is added to ammonia water to obtain a secondary reaction solution (this process is referred to as the "secondary neutralization step"), the tantalum-containing precipitate generated in the secondary reaction solution is washed (this process is referred to as the "washing step"), and the washed tantalum-containing precipitate, amine, and water are mixed to produce a tantalic acid dispersion (this process is referred to as the "dispersion step").

[0089] Alternatively, the tantalic acid compound described later can be used to prepare a tantalic acid dispersion by mixing the tantalic acid compound, an amine, and water.

[0090] However, the method for manufacturing this tantalic acid dispersion is not limited to these methods.

[0091] As long as the above-mentioned steps are included in this dispersion manufacturing method, other steps or other treatments can be appropriately added.

[0092] In addition, for ease of explanation, each process is described below, but each process can be a series of processes in terms of equipment and time, or it can be a process in which the equipment and time are different.

[0093] (Tantalum salt solution)

[0094] The tantalum salt solution used as the starting material can be any solution containing dissolved tantalum. Examples include aqueous solutions of tantalum chloride and tantalum fluoride.

[0095] Tantalum chloride aqueous solution can be prepared by dissolving tantalum chloride (TaCl5) in a small amount of methanol and then adding water.

[0096] On the other hand, tantalum fluoride aqueous solution can react tantalum, tantalum oxide or tantalum hydroxide with hydrofluoric acid (HF) such as hydrofluoric acid aqueous solution to produce tantalum fluoride (H2TaF7), and then dissolve it in water to produce it.

[0097] The aqueous solution of tantalum fluoride is preferably prepared by adding water (e.g., pure water) and containing 1 to 100 g / L of tantalum in terms of Ta₂O₅ concentration. When the tantalum concentration is 1 g / L or higher, it becomes a water-soluble tantalate hydrate. Therefore, the tantalum concentration in the aqueous solution of tantalum fluoride is more preferably 1 g / L or higher in terms of Ta₂O₅ concentration, and further preferably 10 g / L or higher, especially 20 g / L or higher, considering productivity. On the other hand, when the tantalum concentration is 100 g / L or lower, it becomes a water-soluble tantalate hydrate. Therefore, to more reliably synthesize a water-soluble tantalate hydrate, it is more preferably 90 g / L or lower, especially 80 g / L or lower, and particularly 70 g / L or lower.

[0098] From the viewpoint of ensuring complete dissolution of tantalum and / or tantalum oxide, the pH of the aqueous tantalum fluoride solution is preferably 2 or less, and more preferably 1 or less.

[0099] (One neutralization process)

[0100] In this dispersion manufacturing method, it is important to perform a reaction with ammonia water (secondary neutralization) after reacting the tantalum salt solution with the amine aqueous solution (first neutralization).

[0101] If only a single neutralization based on tantalum salt solution and amine aqueous solution is performed without a secondary neutralization based on ammonia, no precipitate will be formed, or the amount of precipitate formed will be reduced, and the yield of this tantalum acid dispersion will easily become low. Furthermore, even if a precipitate is formed, if it is directly washed, some of it will become insoluble hydrates of tantalum acid compounds, making it impossible to obtain a highly dispersible tantalum acid dispersion.

[0102] Furthermore, if the order of primary and secondary neutralization is reversed, and the tantalum salt solution reacts with ammonia water before reacting with amine water, then tantalum and / or tantalic acid cannot be properly dispersed in water during the subsequent dispersion process, and an aqueous solution cannot be prepared.

[0103] In a neutralization process, it is preferable to perform reverse neutralization by adding a tantalum salt solution, such as an aqueous solution of tantalum fluoride, to an aqueous solution of amine to cause a reaction.

[0104] By adding an aqueous amine solution to a tantalum salt solution such as an aqueous tantalum fluoride solution for neutralization, it becomes impossible to properly disperse tantalum and / or tantalum acid in water during subsequent dispersion processes, and it is even more impossible to prepare an aqueous solution.

[0105] It is speculated that through reverse neutralization, the structure of tantalum and / or tantalic acid becomes readily soluble in water.

[0106] Examples of amines that can be used as aqueous solutions of amines in a neutralization process include alkylamines.

[0107] As the aforementioned alkylamine, an alkylamine having 1 to 3 alkyl groups is preferred. In the case of 2 to 3 alkyl groups, all three alkyl groups can be identical; alternatively, different alkyl groups may also be included. From a solubility point of view, the alkyl group of the alkylamine preferably has 1 to 6 carbon atoms, preferably 4 or less, especially 3 or less, and even more especially 2 or less.

[0108] Specific examples of the aforementioned alkylamines include methylamine, dimethylamine, trimethylamine, ethylamine, methyl ethylamine, diethylamine, triethylamine, methyl diethylamine, dimethyl ethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, isopropylamine, diisopropylamine, triisopropylamine, n-butylamine, di-n-butylamine, tri-n-butylamine, isobutylamine, diisobutylamine, triisobutylamine, tert-butylamine, n-pentylamine, n-hexylamine, etc.

[0109] From the perspective of solubility, methylamine, dimethylamine, trimethylamine, ethylamine, methyl ethylamine, diethylamine, triethylamine, methyl diethylamine, and dimethyl ethylamine are preferred, with methylamine, dimethylamine, and trimethylamine being even more preferred.

[0110] In the aforementioned neutralization, from the viewpoint of improving dispersibility, it is preferable to add the aforementioned tantalum salt solution to an aqueous amine solution containing an amine in a molar ratio equal to or greater than the amount of fluorine contained in the tantalum salt solution, i.e., 1 or more. More preferably, it is added to an aqueous amine solution containing 1.2 or more, especially 1.4 or more of the amine.

[0111] On the other hand, from the viewpoint of increasing the amount of waste liquid, it is preferable to add the aforementioned tantalum salt solution to an aqueous amine solution containing an amine with a molar ratio of 2 or less of the fluorine contained in the tantalum salt solution, and more preferably to an aqueous amine solution containing an amine with a molar ratio of 1.8 or less, especially 1.6 or less.

[0112] In a single neutralization step, when adding a tantalum salt solution such as an aqueous tantalum fluoride solution to an aqueous amine solution, it is preferable to carry out the neutralization reaction within 1 minute. That is, it is preferable not to add the aforementioned tantalum salt solution gradually over a long period of time, but rather to add it all at once, for example, within 1 minute, to carry out the neutralization reaction.

[0113] At this time, the addition time of the aforementioned tantalum salt solution is preferably set to within 1 minute, and more preferably within 30 seconds, especially within 10 seconds.

[0114] (Secondary neutralization process)

[0115] In the secondary neutralization process, it is preferable to add the primary reaction solution obtained from the primary neutralization step to ammonia water to obtain the secondary reaction solution. If the primary reaction solution is added to ammonia water, a precipitate will be formed in the water (called "tantalum-containing precipitate").

[0116] From the viewpoint of further improving the dispersibility of this tantalic acid dispersion, it is preferable to also implement reverse neutralization in the secondary neutralization process by adding the primary reaction solution obtained in the primary neutralization process to ammonia water for reaction.

[0117] From the viewpoint of improving the dispersibility of this tantalic acid dispersion, the ammonia concentration of the ammonia solution is preferably 10 to 30% by mass. More preferably, it is 15% by mass or more, particularly 20% by mass or more, and especially 25% by mass or more. On the other hand, more preferably, it is 29% by mass or less, particularly 28% by mass or less.

[0118] In the secondary neutralization process, from the viewpoint of improving the dispersibility in the subsequent dispersion process, it is even more preferable to add the aforementioned primary reaction solution to an ammonia solution containing ammonia with a molar ratio of 7.5 or more, particularly 8.0 or more, especially 8.5 or more, relative to the fluorine contained in the primary reaction solution.

[0119] On the other hand, from the viewpoint of increasing the amount of waste liquid, it is preferable to add the aforementioned primary reaction solution to ammonia water containing ammonia at a molar ratio of 10.0 or less relative to the fluorine contained in the primary reaction solution, and it is even more preferable to add it to ammonia water containing ammonia at a ratio of 9.5 or less, especially 9.0 or less.

[0120] In the secondary neutralization process, when the primary reaction solution is added to the ammonia water, the neutralization reaction is preferably carried out within 1 minute. That is, it is preferable not to add the primary reaction solution gradually over a long period of time, but to add it all at once, for example, within 1 minute, to carry out the neutralization reaction.

[0121] At this time, the addition time of the reaction solution is preferably set to within 1 minute, more preferably within 30 seconds, and especially within 10 seconds.

[0122] (Cleaning process)

[0123] In the secondary reaction solution obtained in the aforementioned secondary neutralization, especially in its tantalum-containing precipitate, unwanted components other than fluorine compounds such as ammonium fluoride, hydrates and / or ions of tantalum and / or tantalic acid, and amines exist in the water as impurities. Therefore, it is preferable to remove these unwanted components.

[0124] Cleaning methods, such as methods for removing fluoride compounds, are arbitrary. For example, in addition to membrane filtration methods based on the use of ammonia, pure water, reverse osmosis filtration, ultrafiltration, precision filtration, etc., centrifugation and other known methods can also be used.

[0125] The cleaning process can be carried out at room temperature, and there is no need to make special temperature adjustments.

[0126] (Distributed processes)

[0127] Next, the tantalum-containing precipitate obtained by the cleaning process, or the tantalum-containing precipitate obtained by fluorine removal, is mixed with a dispersion medium such as water and an amine, and stirred as needed to promote the reaction, thereby producing the tantalum acid dispersion.

[0128] The types of amines added are the same as those that can be used in a single neutralization.

[0129] As described above, the amount of amine added can improve the dispersibility and / or solubility of tantalum and / or tantalic acid relative to water if the amount of amine is too large. However, from the viewpoint that excessive amine may cause adverse effects such as hindering film formation or impeding catalysis, it is preferable to adjust it as described above.

[0130] Each step in this dispersion manufacturing method can be carried out at room temperature, and there is no need to make special temperature adjustments in each step.

[0131] <Applications of this tantalic acid dispersion>

[0132] This tantalic acid dispersion does not contain non-volatile organic components, thus allowing for film formation by drying at relatively low temperatures (below 100°C). Therefore, it can be effectively used, for example, as a various coating solution. Additionally, it can be used for various applications such as as a catalyst feedstock.

[0133] In addition, various additives can be added to this tantalic acid dispersion for various applications.

[0134] <This tantalic acid compound>

[0135] Next, an example of a tantalic acid compound ("this tantalic acid compound") according to an embodiment of the present invention will be described.

[0136] This tantalate compound is preferably partially or wholly an ammonium salt. It may also further contain amines.

[0137] This tantalate compound preferably contains 70 to 95% by mass of tantalum, calculated as Ta2O5, and more preferably 75% or more by mass, particularly 78% or more by mass. On the other hand, it is even more preferably 93% or less by mass, particularly 90% or less by mass.

[0138] It should be noted that this tantalate compound may not exist in the Ta2O5 state. In this invention, the use of a Ta2O5 conversion factor to represent the tantalum content in this tantalate compound is based on the convention in the art for expressing Ta concentration.

[0139] For this tantalate compound, in the X-ray diffraction pattern obtained by powder X-ray diffraction using CuKα rays, the intensity ratio (5.5° / 29°) of the intensity at 2θ = 5.5° to the intensity at 2θ = 29° is preferably 0.90 or higher.

[0140] It was confirmed that the reactivity of this tantalate compound increases when the intensity ratio (5.5° / 29°) at 2θ = 5.5° is greater than that at 2θ = 29°. It was also confirmed that high intensity peaks appearing at angles lower than 2θ = 15° in the X-ray diffraction pattern are characteristic of polyacid structures. Therefore, it can be inferred that a higher intensity ratio (5.5° / 29°) indicates a higher proportion of polyacid structures, and consequently, a higher reactivity of this tantalate compound.

[0141] From this perspective, the strength ratio (5.5° / 29°) of this tantalate compound is preferably 0.90 or higher, more preferably 0.92 or higher, and most preferably 0.94 or higher. It should be noted that the upper limit is expected to be approximately 2.00.

[0142] It should be noted that the aforementioned intensities of 2θ = 29° and 2θ = 5.5° are not the intensities at the peak positions near these angles, but rather specify the intensities at these angles.

[0143] It is presumed that this tantalate compound is a polyacid compound. In particular, it can be presumed to have the formula: [TaxOy] n- Hydrous compounds with the structure shown in [Ta6O](6≤x≤10, 19≤y≤28, n=8, m is an integer from 0 to 50) can be listed. Specifically, those with the structure shown in [Ta6O](6≤x≤10, 19≤y≤28, n=8, m is an integer from 0 to 50) can be listed. 19 ] 8- Hydrous compounds with the structure shown in ·mH2O, etc. However, it is not limited to this type of hydrous compound.

[0144] In addition to the features in the X-ray diffraction pattern, the following aspects can also be listed as evidence for this presumption: high reactivity with alkali metals, and the ability to produce compounds with polyacid structures when mixed and reacted with NaOH, LiOH or KOH.

[0145] (Reactivity with alkali metal compounds)

[0146] This tantalate compound can be reacted with alkali metal salts such as sodium hydroxide and potassium hydroxide, even without heating to above 80°C, to produce alkali metal tantalates.

[0147] For example, in a formulation prepared by slurrying 3g of this tantalic acid compound with 30mL of pure water, 30mL of a 2.2% by mass sodium hydroxide aqueous solution (25°C) was added while stirring, and the mixture was stirred for 15 minutes after addition to obtain a reaction solution. When the precipitate obtained by adding 100mL of ethanol to this reaction solution was dried, a substance containing Na₂O₅ could be obtained. 19 Powder containing 15H2O.

[0148] Therefore, this tantalic acid compound can be said to have high reactivity with alkali metal salts, and as described above, when it reacts with an aqueous solution of sodium hydroxide, it produces Na₂Ta₆O. 19 ·Precipitation of 15H2O.

[0149] Additionally, for example, in a formulation prepared by slurrying 3g of this tantalic acid compound with 30mL of pure water, 30mL of a 3% by mass potassium hydroxide aqueous solution (25°C) was added while stirring, and the mixture was stirred for 15 minutes after addition to obtain a reaction solution. When the precipitate obtained by adding 100mL of ethanol to this reaction solution was dried, a precipitate containing K8Ta6O was obtained. 19 Powder containing ·16H2O.

[0150] Therefore, this tantalate compound can be said to have high reactivity with alkali metal salts, and as described above, when it reacts with an aqueous solution of potassium hydroxide, it produces K8Ta6O. 19 ·Precipitation of 16H2O.

[0151] <Method for manufacturing this compound>

[0152] Next, a suitable method for manufacturing this tantalate compound (referred to as "the method for manufacturing this compound") will be described.

[0153] As an example of the method for manufacturing this compound, a method for manufacturing a tantalic acid compound can be described as follows: A tantalum salt solution is added to an aqueous amine solution to obtain a primary reaction solution (this process is referred to as a "primary neutralization step"), the primary reaction solution is added to ammonia water to obtain a secondary reaction solution (this process is referred to as a "secondary neutralization step"), the tantalum-containing precipitate generated in the secondary reaction solution is washed (this process is referred to as a "washing step"), and the washed tantalum-containing precipitate is dried as needed. In other words, by proceeding up to the washing step in the aforementioned dispersion manufacturing method, the resulting tantalum-containing precipitate or its dried form can be obtained as the tantalic acid compound. That is, the tantalic acid compound can be obtained as an intermediate substance in the manufacture of the tantalic acid dispersion.

[0154] However, the method for manufacturing this compound is not limited to such a method.

[0155] As long as the above-mentioned steps are included in the method for manufacturing this compound, other steps or other treatments may be added as appropriate.

[0156] In addition, for ease of explanation, each process is described below, but each process can be a series of processes in terms of equipment and time, or it can be a process in which the equipment and time are different.

[0157] (Tantalum salt solution)

[0158] The description of the aforementioned tantalum salt solution as the starting material in the method for manufacturing this compound is based on the description of the aforementioned tantalum salt solution in the aforementioned method for manufacturing this dispersion.

[0159] (One neutralization process)

[0160] As an explanation of a neutralization step in the method for manufacturing this compound, the aforementioned explanation of a neutralization step in the method for manufacturing this dispersion is referenced.

[0161] (Secondary neutralization process)

[0162] As an explanation of the secondary neutralization step in the method for manufacturing this compound, the aforementioned explanation of the secondary neutralization step in the method for manufacturing this dispersion is referenced.

[0163] (Cleaning process)

[0164] As an explanation of the cleaning step in the method for manufacturing this compound, the aforementioned explanation of the cleaning step in the method for manufacturing this dispersion is referenced.

[0165] (Drying process)

[0166] The tantalum-containing precipitate obtained after the cleaning process can be directly used as the present tantalum acid compound. Alternatively, the tantalum-containing precipitate can be dried to obtain the present tantalum acid compound.

[0167] The drying method at this time can be any known drying method. Among them, vacuum drying is preferred. Vacuum drying is preferred because it can be easily carried out without setting a high temperature, specifically at a temperature below 100°C.

[0168] Regarding the drying temperature, if the drying temperature is too high, the reactivity of the obtained tantalate compound may decrease. Therefore, the drying temperature is preferably below 100°C, especially below 90°C, especially below 80°C, especially below 70°C, and particularly below 60°C.

[0169] It should be noted that, except for the final drying step, all steps in the manufacturing method of this compound are preferably carried out at room temperature. In this case, it is not necessary to make special temperature adjustments in each step.

[0170] <Uses of this tantalic acid compound>

[0171] This tantalic acid compound can be used to prepare this tantalic acid dispersion. That is, this tantalic acid compound, amine, and water can be mixed to prepare this tantalic acid dispersion.

[0172] Furthermore, although this tantalate compound has somewhat poor reactivity in its dispersion, it has high reactivity with alkali metal salts, such as sodium hydroxide and potassium hydroxide. Even without using an autoclave or other high-temperature and high-pressure conditions, alkali metal tantalates can be easily obtained by simply mixing and reacting with alkali metal salts, such as sodium hydroxide and potassium hydroxide.

[0173] Furthermore, this tantalate compound can be used for various purposes, such as as an additive in catalysts.

[0174] <Explanation of words>

[0175] In this specification, the expression "X to Y" (where X and Y are arbitrary numbers) includes the meaning of "X or more and Y or less" unless otherwise specified, and also includes the meaning of "preferably greater than X" or "preferably less than Y".

[0176] In addition, when expressed as "X or more" (where X is any number) or "Y or less" (where Y is any number), it also implies the intention of "preferably greater than X" or "preferably less than Y".

[0177] Example

[0178] The present invention will be further illustrated by the following embodiments. However, the following embodiments do not limit the present invention.

[0179] (Example 1)

[0180] 137.9 g of tantalum hydroxide (Ta2O5 concentration 66% by mass) manufactured by Mitsui Metals Mining Co., Ltd. was dissolved in 120 g of 55% by mass hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous solution of tantalum fluoride (Ta2O5 concentration 9.1% by mass).

[0181] 100g of the tantalum fluoride aqueous solution was added to 100mL of 50% by mass dimethylamine in less than 1 minute. The mixture was then stirred for 15 minutes to obtain a primary reaction solution (pH 11). This primary reaction solution was then added to 460mL of ammonia water (NH3 concentration 25% by mass) in less than 1 minute to obtain a secondary reaction solution (pH 12). This secondary reaction solution is a slurry of tantalate compound hydrate, in other words, a slurry containing tantalum precipitate.

[0182] Next, the aforementioned secondary reaction solution was decanted using a centrifuge and washed until the free fluoride content in the supernatant was below 100 mg / L, yielding a fluoride-free tantalum precipitate. Ammonia was used as the washing solution at this stage.

[0183] A portion of the aforementioned tantalum-containing precipitate was calcined at 1000°C for 4 hours to generate Ta₂O₅. The concentration of Ta₂O₅ in the tantalum-containing precipitate was calculated based on its mass. The Ta₂O₅ concentration was 38% by mass.

[0184] Add 29.2 mL of pure water and 9 g of 50% by mass dimethylamine to 11.8 g of the aforementioned tantalum precipitate to prepare 50 g of tantalum acid dispersion (sample) with a Ta2O5 concentration of 9% by mass and a dimethylamine concentration of 9% by mass.

[0185] (Example 2)

[0186] 137.9 g of tantalum hydroxide (Ta2O5 concentration 66% by mass) manufactured by Mitsui Metals Mining Co., Ltd. was dissolved in 120 g of 55% by mass hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous solution of tantalum fluoride (Ta2O5 concentration 9.1% by mass).

[0187] 100g of the tantalum fluoride aqueous solution was added to 100mL of 50% by mass dimethylamine in less than 1 minute. The mixture was then stirred for 15 minutes to obtain a primary reaction solution (pH 11). This primary reaction solution was then added to 460mL of ammonia water (NH3 concentration 25% by mass) in less than 1 minute to obtain a secondary reaction solution (pH 12). This secondary reaction solution is a slurry of tantalate compound hydrate, in other words, a slurry containing tantalum precipitate.

[0188] Next, the aforementioned secondary reaction solution was decanted using a centrifuge and washed until the free fluoride content in the supernatant was below 100 mg / L, thereby obtaining a fluoride-free tantalum precipitate. Ammonia was used as the washing solution at this stage.

[0189] A portion of the aforementioned tantalum-containing precipitate was calcined at 1000°C for 4 hours to generate Ta₂O₅. The concentration of Ta₂O₅ in the tantalum-containing precipitate was calculated based on its mass. The Ta₂O₅ concentration was 38% by mass.

[0190] Add 30.2 mL of pure water and 8 g of 50% by mass dimethylamine to 11.8 g of the aforementioned tantalum-containing precipitate to prepare 50 g of tantalum acid dispersion (sample) with a Ta2O5 concentration of 9% by mass and a dimethylamine concentration of 8% by mass.

[0191] (Example 3)

[0192] 137.9 g of tantalum hydroxide (Ta2O5 concentration 66% by mass) manufactured by Mitsui Metals Mining Co., Ltd. was dissolved in 120 g of 55% by mass hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous solution of tantalum fluoride (Ta2O5 concentration 9.1% by mass).

[0193] 100g of the tantalum fluoride aqueous solution was added to 100mL of 50% by mass dimethylamine in less than 1 minute. The mixture was then stirred for 15 minutes to obtain a primary reaction solution (pH 11). This primary reaction solution was then added to 460mL of ammonia water (NH3 concentration 25% by mass) in less than 1 minute to obtain a secondary reaction solution (pH 12). This secondary reaction solution is a slurry of tantalate compound hydrate, in other words, a slurry containing tantalum precipitate.

[0194] Next, the aforementioned secondary reaction solution was decanted using a centrifuge and washed until the free fluoride content in the supernatant was below 100 mg / L, thereby obtaining a fluoride-free tantalum precipitate. Ammonia was used as the washing solution at this stage.

[0195] A portion of the aforementioned tantalum-containing precipitate was calcined at 1000°C for 4 hours to generate Ta₂O₅. The concentration of Ta₂O₅ in the tantalum-containing precipitate was calculated based on its mass. The Ta₂O₅ concentration was 38% by mass.

[0196] Add 31.2 mL of pure water and 7 g of 50% by mass dimethylamine to 11.8 g of the aforementioned tantalum-containing precipitate to prepare 50 g of tantalic acid dispersion (sample) with a Ta2O5 concentration of 9% by mass and a dimethylamine concentration of 7% by mass.

[0197] (Example 4)

[0198] 137.9 g of tantalum hydroxide (Ta2O5 concentration 66% by mass) manufactured by Mitsui Metals Mining Co., Ltd. was dissolved in 120 g of 55% by mass hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous solution of tantalum fluoride (Ta2O5 concentration 9.1% by mass).

[0199] 100g of the tantalum fluoride aqueous solution was added to 100mL of 50% by mass dimethylamine in less than 1 minute. The mixture was then stirred for 15 minutes to obtain a primary reaction solution (pH 11). This primary reaction solution was then added to 460mL of ammonia water (NH3 concentration 25% by mass) in less than 1 minute to obtain a secondary reaction solution (pH 12). This secondary reaction solution is a slurry of tantalate compound hydrate, in other words, a slurry containing tantalum precipitate.

[0200] Next, the aforementioned secondary reaction solution was decanted using a centrifuge and washed until the free fluoride content in the supernatant was below 100 mg / L, thereby obtaining a fluoride-free tantalum precipitate. Ammonia was used as the washing solution at this stage.

[0201] A portion of the aforementioned tantalum-containing precipitate was calcined at 1000°C for 4 hours to generate Ta₂O₅. The concentration of Ta₂O₅ in the tantalum-containing precipitate was calculated based on its mass. The Ta₂O₅ concentration was 38% by mass.

[0202] Add 30.2 mL of pure water and 6 g of 50% by mass dimethylamine to 11.8 g of the aforementioned tantalum precipitate to prepare 50 g of tantalum acid dispersion (sample) with a Ta2O5 concentration of 9% by mass and a dimethylamine concentration of 6% by mass.

[0203] (Example 5)

[0204] 137.9 g of tantalum hydroxide (Ta2O5 concentration 66% by mass) manufactured by Mitsui Metals Mining Co., Ltd. was dissolved in 120 g of 55% by mass hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous solution of tantalum fluoride (Ta2O5 concentration 9.1% by mass).

[0205] 100g of the tantalum fluoride aqueous solution was added to 100mL of 50% by mass dimethylamine in less than 1 minute. The mixture was then stirred for 15 minutes to obtain a primary reaction solution (pH 11). This primary reaction solution was then added to 460mL of ammonia water (NH3 concentration 25% by mass) in less than 1 minute to obtain a secondary reaction solution (pH 12). This secondary reaction solution is a slurry of tantalate compound hydrate, in other words, a slurry containing tantalum precipitate.

[0206] Next, the aforementioned secondary reaction solution was decanted using a centrifuge and washed until the free fluoride content in the supernatant was below 100 mg / L, thereby obtaining a fluoride-free tantalum precipitate. Ammonia was used as the washing solution at this stage.

[0207] A portion of the aforementioned tantalum-containing precipitate was calcined at 1000°C for 4 hours to generate Ta₂O₅. The concentration of Ta₂O₅ in the tantalum-containing precipitate was calculated based on its mass. The Ta₂O₅ concentration was 38% by mass.

[0208] Add 30.2 mL of pure water and 5 g of 50% by mass dimethylamine to 11.8 g of the aforementioned tantalum-containing precipitate to prepare 50 g of tantalum acid dispersion (sample) with a Ta2O5 concentration of 9% by mass and a dimethylamine concentration of 5% by mass.

[0209] (Example 6)

[0210] 137.9 g of tantalum hydroxide (Ta2O5 concentration 66% by mass) manufactured by Mitsui Metals Mining Co., Ltd. was dissolved in 120 g of 55% by mass hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous solution of tantalum fluoride (Ta2O5 concentration 9.1% by mass).

[0211] 100g of the tantalum fluoride aqueous solution was added to 100mL of 50% by mass dimethylamine in less than 1 minute. The mixture was then stirred for 15 minutes to obtain a primary reaction solution (pH 11). This primary reaction solution was then added to 460mL of ammonia water (NH3 concentration 25% by mass) in less than 1 minute to obtain a secondary reaction solution (pH 12). This secondary reaction solution is a slurry of tantalate compound hydrate, in other words, a slurry containing tantalum precipitate.

[0212] Next, the aforementioned secondary reaction solution was decanted using a centrifuge and washed until the free fluoride content in the supernatant was below 100 mg / L, yielding a fluoride-free tantalum precipitate. Ammonia was used as the washing solution at this stage.

[0213] A portion of the aforementioned tantalum-containing precipitate was calcined at 1000°C for 4 hours to generate Ta₂O₅. The concentration of Ta₂O₅ in the tantalum-containing precipitate was calculated based on its mass. The Ta₂O₅ concentration was 38% by mass.

[0214] Add 27.0 mL of pure water and 11.2 g of 40% methylamine to 11.8 g of the aforementioned tantalum precipitate to prepare 50 g of a tantalic acid dispersion (sample) with a Ta2O5 concentration of 9% and a methylamine concentration of 9%

[0215] (Comparative Example 1)

[0216] 137.9 g of tantalum hydroxide (Ta2O5 concentration 66% by mass) manufactured by Mitsui Metals Mining Co., Ltd. was dissolved in 120 g of 55% by mass hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous solution of tantalum fluoride (Ta2O5 concentration 9.1% by mass).

[0217] Add 400 mL of ammonia (NH3 concentration 25% by mass) to 100 g of the tantalum fluoride aqueous solution in less than 1 minute to obtain a reaction solution (pH 12) (positive neutralization). This reaction solution is a slurry of tantalate compound hydrate, in other words, a slurry containing tantalum precipitate.

[0218] Next, the reaction solution was washed using 5C filter paper through a Buchner filtration process until the free fluoride in the supernatant was below 100 mg / L, thus obtaining a fluoride-free tantalum precipitate. Ammonia was used as the washing solution at this stage.

[0219] A portion of the aforementioned tantalum-containing precipitate was calcined at 1000°C for 4 hours to generate Ta₂O₅. The concentration of Ta₂O₅ in the tantalum-containing precipitate was calculated based on its mass. The Ta₂O₅ concentration was 59% by mass.

[0220] Add 33.4 mL of pure water and 9 g of 50% by mass dimethylamine to 7.6 g of the aforementioned tantalum-containing precipitate to prepare 50 g of a tantalum acid-containing liquid (sample) with a Ta2O5 concentration of 9% by mass and a dimethylamine concentration of 9% by mass.

[0221] (Comparative Example 2)

[0222] 137.9 g of tantalum hydroxide (Ta2O5 concentration 66% by mass) manufactured by Mitsui Metals Mining Co., Ltd. was dissolved in 120 g of 55% by mass hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous solution of tantalum fluoride (Ta2O5 concentration 9.1% by mass).

[0223] Add 100g of the tantalum fluoride aqueous solution to 400mL of ammonia water (NH3 concentration 25% by mass) in less than 1 minute to obtain a reaction solution (pH 12) (reverse neutralization). This reaction solution is a slurry of tantalate compound hydrate, in other words, a slurry containing tantalum precipitate.

[0224] Next, the reaction solution was washed using 5C filter paper through a Buchner filtration process until the free fluoride in the supernatant was below 100 mg / L, thus obtaining a fluoride-free tantalum precipitate. Ammonia was used as the washing solution at this stage.

[0225] A portion of the aforementioned tantalum-containing precipitate was calcined at 1000°C for 4 hours to generate Ta₂O₅. The concentration of Ta₂O₅ in the tantalum-containing precipitate was calculated based on its mass. The Ta₂O₅ concentration was 55% by mass.

[0226] Add 32.8 mL of pure water and 9 g of 50% by mass dimethylamine to 8.2 g of the aforementioned tantalum-containing precipitate to prepare 50 g of a tantalum acid-containing liquid (sample) with a Ta2O5 concentration of 9% by mass and a dimethylamine concentration of 9% by mass.

[0227] (Example 7)

[0228] 137.9 g of tantalum hydroxide (Ta2O5 concentration 66% by mass) manufactured by Mitsui Metals Mining Co., Ltd. was dissolved in 120 g of 55% by mass hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous solution of tantalum fluoride (Ta2O5 concentration 9.1% by mass).

[0229] 100g of the tantalum fluoride aqueous solution was added to 100mL of 50% by mass dimethylamine in less than 1 minute. The mixture was then stirred for 15 minutes to obtain a primary reaction solution (pH 11). This primary reaction solution was then added to 460mL of ammonia water (NH3 concentration 25% by mass) in less than 1 minute to obtain a secondary reaction solution (pH 12). This secondary reaction solution is a slurry of tantalate compound hydrate, in other words, a slurry containing tantalum precipitate.

[0230] Next, the aforementioned secondary reaction solution was decanted using a centrifuge and washed until the free fluoride content in the supernatant was below 100 mg / L, yielding a fluoride-free tantalum precipitate. Ammonia was used as the washing solution at this stage.

[0231] A portion of the aforementioned tantalum-containing precipitate was calcined at 1000°C for 4 hours to generate Ta₂O₅. The concentration of Ta₂O₅ in the tantalum-containing precipitate was calculated based on its mass. The Ta₂O₅ concentration was 38% by mass.

[0232] Add 15.3 mL of pure water and 15 g of 50% by mass dimethylamine to 19.7 g of the aforementioned tantalum-containing precipitate to prepare 50 g of tantalic acid dispersion (sample) with a Ta2O5 concentration of 15% by mass and a dimethylamine concentration of 15% by mass.

[0233] (Example 8)

[0234] The amount of tantalum precipitate (Ta2O5 concentration 38% by mass) used in preparing the tantalic acid dispersion was changed to 2.6 g, the amount of pure water was changed to 9995.4 mL, and the amount of 50% by mass dimethylamine was changed to 2 g. Otherwise, the same procedure as in Example 7 was followed to prepare 10 kg of tantalic acid dispersion (sample) with Ta2O5 concentration of 0.01% by mass and dimethylamine concentration of 0.01% by mass.

[0235] (Example 9)

[0236] 137.9 g of tantalum hydroxide (Ta2O5 concentration 66% by mass) manufactured by Mitsui Metals Mining Co., Ltd. was dissolved in 120 g of 55% by mass hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous solution of tantalum fluoride (Ta2O5 concentration 9.1% by mass).

[0237] 100g of the tantalum fluoride aqueous solution was added to 100mL of 50% by mass dimethylamine in less than 1 minute. The mixture was then stirred for 15 minutes to obtain a primary reaction solution (pH 11). This primary reaction solution was then added to 460mL of ammonia water (NH3 concentration 25% by mass) in less than 1 minute to obtain a secondary reaction solution (pH 12). This secondary reaction solution is a slurry of tantalate compound hydrate, in other words, a slurry containing tantalum precipitate.

[0238] Next, the aforementioned secondary reaction solution was decanted using a centrifuge and washed until the free fluoride content in the supernatant was below 100 mg / L, yielding a fluoride-free tantalum precipitate. Ammonia was used as the washing solution at this stage.

[0239] The fluorine-free tantalum-containing precipitate was vacuum dried at 60°C for 15 hours to obtain a tantalate compound (sample).

[0240] (Example 10)

[0241] Instead of 100 mL of 50% by mass dimethylamine used in Example 9, 125 mL of 40% by mass dimethylamine was used, and the same procedure was followed as in Example 9 to obtain the tantalate compound (sample).

[0242] (Comparative Example 3)

[0243] 137.9 g of tantalum hydroxide (Ta2O5 concentration 66% by mass) manufactured by Mitsui Metals Mining Co., Ltd. was dissolved in 120 g of 55% by mass hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous solution of tantalum fluoride (Ta2O5 concentration 9.1% by mass).

[0244] Add 400 mL of ammonia (NH3 concentration 25% by mass) to 100 g of the tantalum fluoride aqueous solution in less than 1 minute to obtain a reaction solution (pH 12) (positive neutralization). This reaction solution is a slurry of tantalate compound hydrate, in other words, a slurry containing tantalum precipitate.

[0245] Next, the reaction solution was washed using 5C filter paper through a Buchner filtration process until the free fluoride in the supernatant was below 100 mg / L, thus obtaining a fluoride-free tantalum precipitate. Ammonia was used as the washing solution at this stage.

[0246] The fluorine-free tantalum-containing precipitate was vacuum dried at 60°C for 15 hours to obtain a tantalate compound (sample).

[0247] (Comparative Example 4)

[0248] 137.9 g of tantalum hydroxide (Ta2O5 concentration 66% by mass) manufactured by Mitsui Metals Mining Co., Ltd. was dissolved in 120 g of 55% by mass hydrofluoric acid aqueous solution, and 849 mL of ion-exchanged water was added to obtain an aqueous solution of tantalum fluoride (Ta2O5 concentration 9.1% by mass).

[0249] 100g of the tantalum fluoride aqueous solution was added to 400mL of ammonia water (NH3 concentration 25% by mass) in less than 1 minute to obtain a reaction solution (pH 12) and thus (reverse neutralization). This reaction solution is a slurry of tantalate compound hydrate, in other words, a slurry containing tantalum precipitate.

[0250] Next, the reaction solution was washed using 5C filter paper through a Buchner filtration process until the free fluoride in the supernatant was below 100 mg / L, thus obtaining a fluoride-free tantalum precipitate. Ammonia was used as the washing solution at this stage.

[0251] The fluorine-free tantalum-containing precipitate was vacuum dried at 60°C for 15 hours to obtain a tantalate compound (sample).

[0252] <Reactivity Test with NaOH>

[0253] Weigh 30 g of the tantalum acid dispersion (sample) obtained in Example 1 or the tantalum-containing liquid (sample) obtained in Comparative Example 2 (at 25°C). While stirring with a magnetic stirrer (stirring speed: 150 rpm), add 30 mL of a 2.2 mass% sodium hydroxide aqueous solution (at 25°C) thereto over 1 minute. After the addition, stir for 15 minutes to obtain a reaction solution. Add 100 mL of ethanol to this reaction solution to obtain a precipitate. Filter the precipitate using a No. 5C filter paper by Buchner filtration, wash it with pure water, and then use a vacuum drying oven to carry out static drying at 60°C under a vacuum (0.08 MPa or less) atmosphere for 15 hours. Crush the obtained dried product with an agate mortar, and perform X-ray diffraction measurement on the obtained powder.

[0254] In addition, weigh 3 g of the tantalum acid compound (sample) obtained in Example 9 or the tantalum acid compound obtained in Comparative Example 3, slurry it with 30 mL of pure water, and while stirring with a magnetic stirrer (stirring speed: 150 rpm), add 30 mL of a 2.2 mass% sodium hydroxide aqueous solution (at 25°C) to this slurry over 1 minute. After the addition, stir for 15 minutes to obtain a reaction solution. Add 100 mL of ethanol to this reaction solution to obtain a precipitate. Filter the precipitate using a No. 5C filter paper by Buchner filtration, wash it with pure water, and then use a vacuum drying oven to carry out static drying at 60°C under a vacuum (0.08 MPa or less) atmosphere for 15 hours. Crush the obtained dried product with an agate mortar, and perform X-ray diffraction measurement on the obtained powder.

[0255] The above X-ray diffraction measurement conditions and X-ray diffraction conditions are the same as the conditions in the following <XRD Measurement>.

[0256] Figure 1 、 Figure 2 The X-ray diffraction patterns of the powders obtained by reacting the tantalum acid dispersion (sample) obtained in Example 1, the tantalum-containing liquid (sample) obtained in Comparative Example 2 with the sodium hydroxide aqueous solution are shown in and

[0257] .

[0257] For the powders obtained by reacting the tantalum acid dispersion (sample) obtained in Example 1 with the sodium hydroxide aqueous solution and the powders obtained by reacting the tantalum acid compound (sample) obtained in Example 9 with the sodium hydroxide aqueous solution, according to the X-ray diffraction measurement results, they are identified as substances formed by Na8Ta6O 19 ·15H2O of ICDD Card No. 00-024-1145.

[0258] On the other hand, for the powder obtained by reacting the tantalum-containing liquid (sample) obtained in Comparative Example 2 with an aqueous sodium hydroxide solution, and the powder obtained by reacting the tantalum acid compound (sample) obtained in Comparative Example 3 with an aqueous sodium hydroxide solution, according to the X-ray diffraction measurement results, it is amorphous and tantalum oxide is not obtained.

[0259] <Reactivity test with KOH>

[0260] Weigh 30 g of the tantalum acid dispersion (sample) obtained in Example 1, and while stirring with a magnetic stirrer (stirring speed: 150 rpm), add 30 mL of a 3 mass% aqueous potassium hydroxide solution thereto over 1 minute. After the addition, stir for 15 minutes to obtain a reaction solution. Add 100 mL of ethanol to this reaction solution to obtain a precipitate. Filter the precipitate using a No. 5C filter paper by Buchner filtration, wash it with pure water, and then use a vacuum drying oven to carry out static drying at 60 °C in an atmosphere of vacuum (0.08 MPa or less) for 15 hours. Crush the obtained dried product with an agate mortar, and perform X-ray diffraction measurement on the obtained powder.

[0261] In addition, weigh 3 g of the tantalum acid compound (sample) obtained in Example 9, and while stirring with a magnetic stirrer (stirring speed: 150 rpm), add 30 mL of a 3 mass% aqueous potassium hydroxide solution thereto over 1 minute. After the addition, stir for 15 minutes to obtain a reaction solution. Add 100 mL of ethanol to this reaction solution to obtain a precipitate. Filter the precipitate using a No. 5C filter paper by Buchner filtration, wash it with pure water, and then use a vacuum drying oven to carry out static drying at 60 °C in an atmosphere of vacuum (0.08 MPa or less) for 15 hours. Crush the obtained dried product with an agate mortar, and perform X-ray diffraction measurement on the obtained powder.

[0262] At this time, the X-ray diffraction measurement conditions and X-ray diffraction conditions are the same as those in the following <XRD measurement>.

[0263] Figure 3 The X-ray diffraction pattern of the powder obtained by reacting the tantalum acid dispersion (sample) obtained in Example 1 with an aqueous potassium hydroxide solution is shown.

[0264] For the powder obtained by reacting the tantalum acid dispersion (sample) obtained in Example 1 with an aqueous potassium hydroxide solution, according to the X-ray diffraction measurement results, it was identified as a substance formed by K8Ta6O 19 ·16H2O of ICDD card No. 01-073-8508.

[0265] In addition, the powder obtained by reacting the tantalum acid compound (sample) obtained in Example 9 with an aqueous potassium hydroxide solution was also identified as a substance formed of K8Ta6O 19 ·16H2O according to the X-ray diffraction measurement results, as per ICDD card No. 01-073-8508.

[0266] <XRD Measurement>

[0267] Using a vacuum drying oven, 10 g of the tantalum acid dispersion liquid (sample) obtained in Examples 1 to 8 or the tantalum acid-containing liquid (sample) obtained in Comparative Examples 1 to 2 was allowed to stand for 15 hours in an atmosphere of 60 °C and vacuum (0.08 MPa or less) to be dried, obtaining a powder (sample) of the tantalum acid compound.

[0268] Powder X-ray diffraction measurement using CuKα rays was performed on these powders (samples) of tantalum oxides and the tantalum acid compounds obtained in Examples 9 and 10 and Comparative Examples 3 and 4, obtaining X-ray diffraction patterns.

[0269] Figures 4-11 The X-ray diffraction patterns of the powders (samples) of tantalum oxides respectively obtained from the tantalum acid dispersion liquids (samples) obtained in Examples 1 to 6 or the tantalum acid-containing liquids (samples) obtained in Comparative Examples 1 to 2 are shown.

[0270] =X-ray Diffraction Measurement Conditions=

[0271] · Apparatus: MiniFlexII (manufactured by Rigaku Corporation)

[0272] · Measurement range (2θ): 5 to 90°

[0273] · Sampling width: 0.02°

[0274] · Scanning speed: 2.0° / minute

[0275] · X-ray: CuKα ray

[0276] · Voltage: 30 kV

[0277] · Current: 15 mA

[0278] · Divergence slit: 1.25°

[0279] · Scattering slit: 1.25°

[0280] · Receiving slit: 0.3 mm

[0281] =X-ray Diffraction Analysis Conditions=

[0282] · Data analysis software PDXL2 manufactured by Rigaku Corporation was used.

[0283] • To make the peaks clear, b-spling is used to smooth them.

[0284] Based on the measured X-ray diffraction patterns, the intensities at 2θ = 5.5° and 2θ = 29° were determined, and the ratio of the intensity at 2θ = 5.5° to the intensity at 2θ = 29° (5.5° / 29° intensity ratio) was calculated. The dried products of the tantalic acid dispersions (samples) of Examples 1 to 8 and Comparative Example 2 are shown in Table 3, and the tantalic acid compounds (samples) of Examples 9 and 10 and Comparative Examples 3 and 4 are shown in Table 4.

[0285] <Transmittance Measurement>

[0286] The transmittance of the tantalic acid dispersions (samples) obtained in Examples 1-8 or the tantalic acid-containing liquids (samples) obtained in Comparative Examples 1-2 was measured using a spectrophotometer.

[0287] =Transmittance Measurement Conditions=

[0288] • Apparatus: UH4150 spectrophotometer

[0289] Measurement mode: Wavelength scan

[0290] • Data mode: %T (transmission)

[0291] • Measurement wavelength range: 200–2600 nm

[0292] • Scanning speed: 600nm / minute

[0293] • Sampling interval: 2nm

[0294] Based on the measured transmittance, the transmittance at a wavelength of 400 nm was calculated and is shown in Table 5.

[0295] [Table 1]

[0296]

[0297] [Table 2]

[0298]

[0299] [Table 3]

[0300]

[0301] [Table 4]

[0302]

[0303] [Table 5]

[0304] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Comparative Example 1 Comparative Example 2 Transmittance at 400nm 100.0 98.3 81.9 73.4 56.3 100.0 51.3 100 0.7 1.0

[0305] (Inspection)

[0306] The tantalic acid dispersions (samples) obtained in Examples 1 to 6 were left to stand at room temperature for 48 hours, and then observed. As a result, no precipitation was observed in any sample, confirming that it was in the state of a dispersion.

[0307] In contrast, the tantalic acid-containing liquids (samples) obtained in Comparative Examples 1 and 2 were left to stand at room temperature for 48 hours, and then observed. Precipitation was observed in all samples.

[0308] For the tantalic acid dispersions (samples) obtained in Examples 1-6, it is clear from the manufacturing method that the water contains only unavoidable impurities other than tantalum and / or tantalic acid hydrates and / or their ions and amines. These unavoidable impurities are assumed to be fluorine compounds, ammonia, etc. Therefore, it is clear that the tantalic acid dispersions (samples) obtained in Examples 1-6 are at least free of organic components, especially non-volatile organic components.

[0309] Based on the above embodiments and the experimental results conducted by the inventors to date, it has been confirmed that for a tantalic acid dispersion containing tantalum and / or tantalic acid and an amine in water, and for a tantalic acid dispersion for which the intensity ratio (5.5° / 29°) of the intensity at 2θ = 5.5° to the intensity at 2θ = 29° is 1.00 or higher in the X-ray diffraction pattern obtained by powder X-ray diffraction of the dried tantalic acid dispersion using CuKα rays, its dispersibility in water is high even without the presence of non-volatile organic components such as hydroxycarboxylic acids, oxalic acid, and EDTA. Furthermore, it has been found that increasing the amine content can further improve the dispersibility in water and increase the transmittance.

[0310] Furthermore, it is known that the above-mentioned tantalic acid dispersion has high reactivity with alkali metal salts such as sodium hydroxide and potassium hydroxide. Even without using an autoclave or other high-temperature and high-pressure conditions for reaction, alkali metal tantalates can be easily obtained simply by mixing and reacting with alkali metal salts such as sodium hydroxide and potassium hydroxide.

[0311] Based on the fact that the high intensity of the peak appearing at an angle lower than 2θ = 15° in the X-ray diffraction pattern is one of the characteristics of the polyacid structure, and that it has high reactivity with alkali metals and can produce compounds with polyacid structures when mixed and reacted with NaOH, LiOH or KOH, it can be inferred that in this tantalic acid dispersion, tantalum and / or tantalic acid exist in water in the form of ions of a polyacid structure formed by ionic bonding with amines.

[0312] On the other hand, based on the above embodiments and the experimental results conducted by the inventors so far, it can be seen that the tantalate compound with an intensity ratio (5.5° / 29°) of 0.90 or higher at 2θ = 5.5° to 2θ = 29° in the X-ray diffraction pattern is highly reactive with alkali metal salts, such as sodium hydroxide and potassium hydroxide. Even without using an autoclave or other high-temperature and high-pressure conditions for reaction, alkali metal tantalates can be easily obtained simply by mixing and reacting with alkali metal salts, such as sodium hydroxide and potassium hydroxide.

[0313] Furthermore, for such tantalate compounds, in addition to the features in the X-ray diffraction pattern, they can also be inferred to be compounds with a polyacid structure based on the fact that they can be reacted with alkali metal salts to obtain alkali metal tantalates with polyacid structures.

Claims

1. A tantalic acid dispersion, characterized in that, The tantalic acid dispersion contains tantalum and / or tantalic acid in water and contains an amine, wherein the tantalum and / or tantalic acid exist in water in the form of an ion with a polyacid structure formed by ionic bonding with the amine, the polyacid structure being of the formula: [Ta x O y ] n- The structure shown in ·mH2O, where 6≤x≤10, 19≤y≤28, n=8, and m is an integer from 0 to 50, When the powder obtained by drying the tantalic acid dispersion was subjected to powder X-ray diffraction using CuKα rays, the intensity ratio of the intensity at 2θ = 5.5° to the intensity at 2θ = 29° in the X-ray diffraction pattern was greater than 1.00 (5.5° / 29°).

2. A tantalic acid dispersion, characterized in that, It is a dispersion of tantalic acid in water containing both tantalic acid and amine, wherein the tantalic acid exists in water in the form of a polyacid structure formed by ionic bonding with the amine, and the polyacid structure is of the formula: [Ta x O y ] n- The structure shown in ·mH2O, where 6≤x≤10, 19≤y≤28, n=8, and m is an integer from 0 to 50, The transmittance at 400nm is over 40%.

3. A tantalic acid dispersion, characterized in that, The tantalic acid dispersion contains tantalum and / or tantalic acid in water and contains an amine, wherein the tantalum and / or tantalic acid exist in water in the form of an ion with a polyacid structure formed by ionic bonding with the amine, the polyacid structure being of the formula: [Ta x O y ] n- The structure shown in ·mH2O, where 6≤x≤10, 19≤y≤28, n=8, and m is an integer from 0 to 50, When powder X-ray diffraction (PXRD) of the powder obtained by drying the tantalic acid dispersion was performed using CuKα rays, the intensity ratio (5.5° / 29°) of the intensity at 2θ = 5.5° to the intensity at 2θ = 29° in the X-ray diffraction pattern was greater than 1.

00. The transmittance at 400nm is over 40%.

4. The tantalic acid dispersion according to any one of claims 1 to 3, characterized in that, To 30g of a 25°C dispersion of tantalic acid, adjusted to contain 9% tantalum by mass (Ta₂O₅ equivalent), 30mL of a 2.2% tantalum hydroxide aqueous solution at 25°C was added while stirring. The mixture was stirred for 15 minutes after addition to generate a reaction solution. When 100mL of ethanol was added to this reaction solution, Na₈Ta₆O₆ was formed. 19 ·Precipitation of 15H2O.

5. The tantalic acid dispersion according to any one of claims 1 to 3, characterized in that, To 30g of a tantalic acid dispersion at 25°C, adjusted to contain 9% tantalum by mass (Ta₂O₅ equivalent), 30mL of a 3% potassium hydroxide aqueous solution at 25°C was added while stirring. The mixture was stirred for 15 minutes after addition to generate a reaction solution. When 100mL of ethanol was added to this reaction solution, K₈Ta₆O₆ was formed. 19 ·Precipitation of 16H2O.

6. The tantalic acid dispersion according to any one of claims 1 to 3, characterized in that, It contains 0.01 to 30% by mass of amine.

7. The tantalic acid dispersion according to any one of claims 1 to 3, characterized in that, It contains 0.01 to 40% by mass of tantalum, calculated as Ta2O5.

8. A method for manufacturing a tantalic acid dispersion, characterized in that, A tantalum salt solution is added to an aqueous amine solution to obtain a primary reaction solution, termed primary neutralization. This primary reaction solution is then added to ammonia water to obtain a secondary reaction solution, termed secondary neutralization. The tantalum-containing precipitate produced in the secondary reaction solution is washed. The washed tantalum-containing precipitate, amine, and water are then mixed to prepare a tantalum acid dispersion. In the tantalic acid dispersion, tantalum and / or tantalic acid exist in water in the form of a polyacid structure formed by ionic bonding with an amine, wherein the polyacid structure is of the formula: [Ta x O y ] n- The structure shown in ·mH2O is given, where 6≤x≤10, 19≤y≤28, n=8, and m is an integer from 0 to 50.

9. The method for manufacturing the tantalic acid dispersion according to claim 8, characterized in that, In the first neutralization, the tantalum salt solution is added to an aqueous amine solution containing an amount of amine equal to or greater than the amount of fluorine contained in the tantalum salt solution in a molar ratio.

10. The method for manufacturing the tantalic acid dispersion according to claim 8 or 9, characterized in that, In the secondary neutralization, the primary reaction solution is added to an ammonia solution containing ammonia at a molar ratio of more than 7.5 times the amount of fluorine contained in the primary reaction solution.

11. A tantalic acid compound, characterized in that, When performing powder X-ray diffraction measurements using CuKα rays, in the X-ray diffraction pattern, the intensity ratio (5.5° / 29°) of the intensity at 2θ = 5.5° to the intensity at 2θ = 29° is greater than 0.

90. The tantalate compound has a polyacid structure, which is of the formula: [Ta x O y ] n- The structure shown in ·mH2O is given, where 6≤x≤10, 19≤y≤28, n=8, and m is an integer from 0 to 50.

12. The tantalate compound according to claim 11, wherein some or all of it is an ammonium salt.

13. A method for forming a film on the surface of a component, wherein, The tantalic acid dispersion according to any one of claims 1 to 9 is applied to the surface of the component.

14. A surface layer film-forming component, which is obtained by coating the tantalic acid dispersion according to any one of claims 1 to 9 onto the surface of the component.

Images