Zirconium-modified niobate sol

Abstract

To develop a niobate sol with varied index of refraction, and to develop a novel niobate sol applicable to battery materials.SOLUTION: It is a dispersed sol containing dispersed particles that include core particles and modifiers that modify the surface of the core particles, where the core particles contain niobic acid, the modifiers contain zirconium components, and a molar ratio of ZrO2 / Nb2O5 is in the range of 0.01 to 0.15, known as zirconium-modified niobic acid sol. The zirconium-modified niobate sol can be produced through a process consisting of (1) a first step of mixing a niobate sol with a pH of 7 or higher and a zirconium compound, and (2) a second step of heating.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a zirconium modified niobic acid sol. [Background technology]

[0002] In recent years, materials that take advantage of niobium's high refractive index have been developed, and in the field of battery materials, niobium-based sols have been attracting attention as a surface coating material for positive and negative electrodes.

[0003] The applicant first invented a technology relating to ammonium niobate sol as a niobic acid sol, as described in Patent Document 1, and then invented an amine compound-stabilized niobic acid sol and an amine compound / organic acid-stabilized niobic acid sol as described in Patent Document 2, and an alkali metal-stabilized niobic acid sol as described in Patent Document 3, and further invented a lithium-phosphate-stabilized niobic acid sol as described in Patent Document 4. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5441264 [Patent Document 2] Patent No. 6156876 [Patent Document 3] Patent No. 6774158 [Patent Document 4] Patent No. 7161276 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to develop a niobic acid sol with a varied refractive index, and a new niobic acid sol that can be used as a battery material. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to discover new possibilities for niobic acid sol, and have come up with the idea of ​​modifying the surface of dispersed particles of niobic acid sol with zirconium, which is used in various applications such as optical materials, battery materials, and catalysts. The present invention is as follows. [1] A sol in which dispersed particles containing core particles and a modifier that modifies the surface of the core particles are dispersed, the core particles containing niobic acid, the modifier containing a zirconium component, and the molar ratio of ZrO2 / Nb2O5 being in the range of 0.01 to 0.15. [2] A method for producing the zirconium-modified niobic acid sol according to [1] above, comprising the following steps: (1) A first step of mixing a niobic acid sol having a pH of 7 or more with a zirconium compound (2) The second heating step DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The present invention will be described in detail below based on preferred embodiments, but the present invention is not limited to the following embodiments and various modifications are possible within the scope of the claims. In addition, in the present invention, the expression "numeric value 1 to numerical value 2" regarding a numerical range means a numerical range including both the numerical values ​​1 and 2, with numerical value 1 being the lower limit and numerical value 2 being the upper limit, and is synonymous with "numerical value 1 or more and numerical value 2 or less."

[0008] The present invention relates to a zirconium-modified niobic acid sol (hereinafter referred to as "the sol of the present invention"), which is a sol in which dispersed particles containing core particles and a modifier that modifies the surface of the core particles are dispersed, the core particles contain niobic acid, the modifier contains a zirconium component, and the molar ratio of ZrO2 / Nb2O5 is in the range of 0.01 to 0.15.

[0009] The core particles include niobic acid. A good example of the core particles is a dispersed particle in an ammonium niobate sol described in Patent Document 1, and the dispersed particle is composed of amorphous ammonium niobate. Another good example of the core particles is a dispersed particle in an amine compound stabilized niobic acid sol described in Patent Document 2, and the dispersed particle is a particle in which the ammonia content in amorphous ammonium niobate is reduced and the dispersion is stabilized by an amine compound instead of ammonia. Another good example of the core particles is a dispersed particle in an amine compound / organic acid stabilized niobic acid sol described in Patent Document 2, and the dispersed particle is a particle in which the ammonia content in amorphous ammonium niobate is reduced and the dispersion is stabilized by an amine compound and an organic acid instead of ammonia. Another good example of the core particles is a dispersed particle in an alkali metal stabilized niobic acid sol described in Patent Document 3, and the dispersed particle has the following two patterns (a) and (b). In the case of (a), it is a {complex of niobic acid and an alkali metal}, and in the case of (b), it is a {complex of niobic acid and ammonia} in addition to a {complex of niobic acid and an alkali metal}. Furthermore, the core particles may be composed of two or more types of dispersed particles among the preferred examples given above.

[0010] The modification contains a zirconium component. The modification may contain a subcomponent other than the zirconium component. Examples of the subcomponent include ammonia and alkali metals. Examples of the alkali metal include lithium, sodium, and potassium.

[0011] The dispersed particles include the above-mentioned core particles and a modifier that modifies the surface of the core particles, and the dispersed particles have the properties of a sol due to their dispersed state. Since the sol of the present invention has a ZrO2 / Nb2O5 (molar ratio) in the range of 0.01 to 0.15, the ratio of the modifier to the core particles is low, and therefore the dispersibility of the dispersed particles largely depends on the dispersibility of the core particles.

[0012] The particle size of the dispersed particles is not particularly limited as long as the properties of the sol are obtained, but for example, the average particle size of the dispersed particles is preferably within the range of 5 to 100 nm. Here, the average particle size of the dispersed particles refers to the median size when the sol of the present invention is measured using a dynamic light scattering particle size distribution measuring device "LB-500" manufactured by Horiba, Ltd.

[0013] In the sol of the present invention, the ZrO2 / Nb2O5 (molar ratio) is in the range of 0.01 to 0.15. If it is less than 0.01, it becomes difficult to obtain the modifying effect of zirconium oxide. On the other hand, if it exceeds 0.15, the sol becomes easily unstable.

[0014] The Nb2O5 concentration in the sol of the present invention is preferably, for example, in the range of 1 to 10 mass%. The lower limit of the concentration is more preferably 3 mass% from the viewpoint of economics in terms of production and transportation. The upper limit of the concentration is more preferably 8 mass% from the viewpoint of production. When adjusting the concentration of the sol of the present invention, it may be carried out by a conventional method within a range in which a stable state of the sol is maintained, and examples of such methods include concentration by heating or vacuum concentration, dilution with water, etc.

[0015] The refractive index of the sol of the present invention is preferably in the range of 1.60 to 1.75. The refractive index here is measured by using the sol of the present invention as a coating liquid in its pure form, spin-coating it on a slide glass, and then drying it at 100°C for 30 minutes to obtain a thin film-supported substrate, and using a thin film measuring device F-20 (manufactured by FILMETRICS Co., Ltd.). The preferred range of the refractive index is when the film thickness of the thin film formed by spin-coating is preferably 150±25 nm.

[0016] A preferred method for producing the sol of the present invention comprises the following steps: (1) A first step of mixing a niobic acid sol having a pH of 7 or more with a zirconium compound (2) The second heating step

[0017] The niobic acid sol having a pH of 7 or more is not particularly limited as long as the sol has a pH of 7 or more, and examples thereof include the ammonium niobate sol described in Patent Document 1, the amine compound-stabilized niobic acid sol and the amine compound / organic acid-stabilized niobic acid sol described in Patent Document 2, and the alkali metal-stabilized niobic acid sol described in Patent Document 3. Examples of commercially available products include "Bailar Nb-G6000" manufactured by Taki Chemical Industry Co., Ltd. as an ammonium niobate sol, "Bailar Nb-G6600" manufactured by the same company as an amine compound / organic acid-stabilized niobic acid sol, and "Bailar Nb-G6700" manufactured by the same company as an alkali metal-stabilized niobic acid sol. Only one type of niobic acid sol may be used, or multiple types may be used.

[0018] The zirconium compound is preferably a zirconium salt that dissolves in water and exhibits alkalinity (water-soluble alkaline zirconium salt), and preferred examples are ammonium zirconium carbonate, potassium zirconium carbonate, etc. Only one type of zirconium compound may be used, or multiple types may be used.

[0019] A mixed liquid is obtained by mixing a niobic acid sol having a pH of 7 or more with a zirconium compound. The mixed liquid is preferably in the form of a sol. This is because if the mixed liquid gels, it is difficult to obtain a sol in the final product. There is no particular limitation on the mixing method, and mixing may be performed by a conventional method. For example, a zirconium compound is added to a niobic acid sol under stirring. The zirconium compound may be liquid or solid, but it is particularly preferable to use a liquid. In addition, when a solid is used, it is particularly preferable to use a powder, and it may be dispersed in a small amount of water.

[0020] In the second step, the mixture obtained in the first step is heated. The heating is not particularly limited as long as a sol is obtained, and for example, the heating temperature is preferably in the range of 70 to 120°C. The upper limit of the above range is more preferably 110°C. Thus, a more preferable heating temperature range is, for example, 70 to 110°C. The heating time may be appropriately adjusted depending on the heating temperature, and is preferably, for example, in the range of 1 to 8 hours.

[0021] After the second step, any step may be carried out, such as a washing step, a concentration adjustment step, etc. There is no particular limitation on the washing method, but ultrafiltration while adding water is preferred.

[0022] Although the mechanism by which the surface of the core particles is modified by the modifier is not clear, it is assumed that the modifier is present in a state of being bound or adsorbed to the surface of the core particles. In terms of the zirconium component, it is assumed that the zirconium component derived from the zirconium compound neutralized or hydrolyzed by the niobic acid on the surface of the core particles by heating in the second step is bound or adsorbed. The form of the compound of the zirconium component is thought to be zirconium oxide or zirconium hydroxide.

[0023] The sol of the present invention can be suitably used in various applications, including, for example, a coating solution for forming a transparent thin film, an additive for secondary batteries, electronic materials, and a catalyst, which contains the sol of the present invention. EXAMPLES

[0024] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these.

[0025] (raw materials) The ammonium niobate sol used was "Baylal Nb-G6000" (Nb2O5 concentration: 6 mass%, pH 8) manufactured by Taki Chemical Co., Ltd. The amine compound / organic acid stabilized niobate sol used was "Baylal Nb-G6600" (Nb2O5 concentration: 6 mass%, pH 8) manufactured by the same company, and the alkali metal stabilized niobate sol used was "Baylal Nb-G6700" (Nb2O5 concentration: 6 mass%, pH 8) manufactured by the same company.

[0026] Example 1 7.3 g of an aqueous solution of ammonium zirconium carbonate (ZrO2 concentration: 20 mass%) was added to 1000 g of ammonium niobate sol under stirring, and then heated at 100°C for 2 hours to obtain a zirconium-modified niobate sol of Example 1 having a ZrO2 / Nb2O5 (molar ratio) of 0.05.

[0027] [Examples 2 to 9] 15.4 g of an aqueous solution of ammonium zirconium carbonate (ZrO2 concentration: 20 mass%) was added to 1000 g of ammonium niobate sol under stirring, and then heated under the heating conditions shown in Table 1 to obtain zirconium-modified niobate sols of Examples 2 to 9 having a ZrO2 / Nb2O5 (molar ratio) of 0.11.

[0028] Example 10 To 1000 g of ammonium niobate sol under stirring, 20.7 g of an aqueous solution of ammonium zirconium carbonate (ZrO2 concentration: 20 mass%) was added, and then the mixture was heated at 100°C for 2 hours. Ion-exchanged water was then added to obtain a zirconium-modified niobate sol of Example 10 having a ZrO2 / Nb2O5 (molar ratio) of 0.15.

[0029] Example 11 To 1,000 g of the amine compound / organic acid stabilized niobic acid sol under stirring was added 15.4 g of an aqueous solution of ammonium zirconium carbonate (ZrO2 concentration: 20% by mass), and the mixture was heated at 90°C for 2 hours to obtain the zirconium-modified niobic acid sol of Example 11 having a ZrO2 / Nb2O5 (molar ratio) of 0.11.

[0030] Example 12 To 1000 g of alkali metal stabilized niobic acid sol under stirring, 15.4 g of an aqueous solution of ammonium zirconium carbonate (ZrO2 concentration: 20% by mass) was added, and then heated at 90°C for 2 hours to obtain a zirconium-modified niobic acid sol of Example 12 having a ZrO2 / Nb2O5 (molar ratio) of 0.11.

[0031] Example 13 7.7 g of potassium zirconium carbonate solution (ZrO2 concentration: 19 mass%) was added to 1000 g of ammonium niobate sol under stirring, and then heated at 100°C for 2 hours to obtain a zirconium-modified niobic acid sol of Example 13 having a ZrO2 / Nb2O5 (molar ratio) of 0.05.

[0032] [Examples 14 to 21] 16.3 g of potassium zirconium carbonate aqueous solution (ZrO2 concentration: 19 mass%) was added to 1000 g of ammonium niobate sol under stirring, and then heated under the heating conditions shown in Table 1 to obtain zirconium-modified niobic acid sols of Examples 14 to 21 having a ZrO2 / Nb2O5 (molar ratio) of 0.11.

[0033] Example 22 To 1000 g of ammonium niobate sol under stirring, 21.9 g of an aqueous solution of potassium zirconium carbonate (ZrO2 concentration: 19 mass%) was added, and then the mixture was heated at 100°C for 2 hours. Ion-exchanged water was then added to obtain a zirconium-modified niobic acid sol of Example 22 having a ZrO2 / Nb2O5 (molar ratio) of 0.15.

[0034] Example 23 To 1,000 g of the amine compound / organic acid stabilized niobic acid sol under stirring was added 16.3 g of an aqueous solution of potassium zirconium carbonate (ZrO2 concentration: 19 mass%), and then the mixture was heated at 90°C for 2 hours to obtain the zirconium-modified niobic acid sol of Example 23 having a ZrO2 / Nb2O5 (molar ratio) of 0.11.

[0035] Example 24 To 1,000 g of alkali metal-stabilized niobic acid sol under stirring, 16.3 g of an aqueous solution of potassium zirconium carbonate (ZrO2 concentration: 19% by mass) was added, and then heated at 90°C for 2 hours to obtain a zirconium-modified niobic acid sol of Example 24 having a ZrO2 / Nb2O5 (molar ratio) of 0.11.

[0036] Comparative Example 1 25.0 g of an aqueous solution of ammonium zirconium carbonate (ZrO2 concentration: 20 mass%) was added to 1000 g of ammonium niobate sol under stirring (ZrO2 / Nb2O5 (molar ratio) = 0.18), and then heated at 100°C for 2 hours, but gelation occurred and no sol was obtained.

[0037] Comparative Example 2 25.8 g of potassium zirconium carbonate aqueous solution (ZrO2 concentration: 19 mass%) was added to 1000 g of ammonium niobate sol under stirring (ZrO2 / Nb2O5 (molar ratio) = 0.18), and then heated at 100°C for 2 hours, but gelation occurred and no sol was obtained.

[0038] (Analysis method) The zirconium-modified niobic acid sols obtained in Examples 1 to 24 were subjected to the following analyses in their as-is form. pH: Measured using a Horiba pH meter "D-53." ·EC: Measured using an EC meter "CM42-X" manufactured by DKK-TOA Corporation. Haze and total light transmittance: Measured using a haze meter "COH7700" manufactured by Nippon Denshoku Industries Co., Ltd., at wavelengths of 400 to 700 nm (10 nm intervals) and an optical path length of 10 mm. Average particle size: Measured using a dynamic light scattering particle size distribution analyzer "LB-500" manufactured by Horiba Ltd. Viscosity: The liquid temperature was set to 25°C and measurements were taken using a Toki Sangyo Co., Ltd. E-type viscometer "TVE-25L" (rotor: 1°34' x R24). (Refractive index measurement) The zirconium-modified niobic acid sol obtained in Examples 1 to 24 was used as a coating solution in its pure form, spin-coated onto a slide glass, and then dried for 30 minutes at 100° C. to obtain a thin film-supported substrate. The refractive index of the thin film-supported substrate was measured using a thin film measuring device F-20 (manufactured by FILMETRICS).

[0039] The results are shown in Table 1. Among the examples in Table 1, those with high total light transmittance, especially those with 90% or more, are applicable as optical materials. The ammonium niobate sol had a total light transmittance of 90.4% and a refractive index of 1.76 (film thickness: 142 nm).

[0040] [Table 1]

Claims

1. A sol in which dispersed particles containing core particles and a modifying substance that modifies the surface of the core particles are dispersed, the core particles contain niobic acid; the modification comprises a zirconium component; ZrO 2 / Nb 2 O 5 (molar ratio) is in the range of 0.01 to 0.15; Zirconium modified niobate sol.

2. 2. A method for producing the zirconium modified niobic acid sol of claim 1, comprising the steps of: (1) A first step of mixing a niobic acid sol having a pH of 7 or more with a zirconium compound (2) The second heating step

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