JP2017214277A - Zirconium oxide nanoparticle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite zirconium oxide nanoparticle coated by a coating agent by finding an element which is other than aluminum, magnesium, titanium and yttrium and is polymerizable with zirconium oxide nanoparticle.SOLUTION: There is provided a zirconium oxide particle coated by first carboxylic acid having 3 or more carbon atoms, and containing at least one kind of metal element selected from La, Ce, Eu, Fe, Co, Sn, Zn, In, Bi, Mn, Ni and Cu, excluding yttrium. There is provided a zirconium oxide particle where the first carboxylic acid is one or more kinds selected from secondary carboxylic acid, carboxylic acid of which carbon atoms other than α position are branched and linear carboxylic acid having 4 to 20 carbon atoms.SELECTED DRAWING: Figure 1

Description

  The present invention relates to zirconium oxide nanoparticles.

  In recent years, metal oxide nanoparticles have been applied in a wide range of fields such as optical materials, pharmaceuticals, ceramics, and electronic materials, and have attracted a great deal of attention. However, metal oxides alone are often agglomerated due to insufficient dispersibility in an organic medium, causing problems such as a decrease in transparency and a decrease in mechanical strength. In order to impart good dispersibility to an organic medium, a method of chemically bonding an organic group to a metal oxide has been proposed.

For example, Patent Document 1 is coated with two or more coating agents, and at least one of the coating agents is represented by the formula R ¹ —COOH (R ¹ is a hydrocarbon group having 6 or more carbon atoms). Zirconium oxide nanoparticles are disclosed.

  In addition, the functions of single metal oxide nanoparticles are limited, and composite oxide nanoparticles that may exhibit more specific performance have attracted attention.

  As composite oxide nanoparticles, for example, Patent Document 2 discloses stabilized zirconia fine particles containing yttrium or the like. Patent Document 3 discloses a zirconium oxide dispersion containing aluminum, magnesium, titanium, or yttrium as a stabilizing element.

JP 2008-44835 A JP 2008-184339 A JP 2014-80361 A

  However, for elements other than the stabilizing elements disclosed in Patent Documents 2 and 3, it is not clear whether or not composite oxide nanoparticles combined with zirconium oxide can be obtained. It is also not clear whether a particle coated with a coating can be realized.

  Therefore, an object of the present invention is to find an element that can be combined with zirconium oxide nanoparticles with an element other than aluminum, magnesium, titanium, and yttrium, and to provide composite zirconium oxide nanoparticles coated with a coating agent.

  The present invention relates to zirconium oxide nanoparticles coated with a first carboxylic acid having 3 or more carbon atoms, and includes La, Ce, Eu, Fe, Co, Sn, Zn, In, Bi, Mn, Ni, and Cu. Zirconium oxide nanoparticles containing at least one metal element selected from the group consisting of (but not containing yttrium).

  The first carboxylic acid is preferably at least one of a primary carboxylic acid and a secondary carboxylic acid, and in particular, a secondary carboxylic acid, a carboxylic acid having a branched carbon atom other than the α-position, and a carbon number of 4 to It is preferably at least one selected from the group consisting of 20 linear carboxylic acids.

  In the present invention, the total content of at least one metal element selected from the group consisting of La, Ce, Eu, Fe, Co, Sn, Zn, In, Bi, Mn, Ni and Cu is It is preferable that it is 0.1-40 mass% in the ratio with respect to the total content of zirconium.

  The present invention also includes a dispersion containing the above-described zirconium oxide nanoparticles of the present invention, a resin composition, and a molding material.

  Furthermore, the present invention also includes a ceramic material obtained from the above-described zirconium oxide nanoparticles of the present invention, a method for producing a ceramic material in which the above-described zirconium oxide nanoparticles of the present invention are fired at 500 ° C. or higher, and the above-described book A method for producing a ceramic material in which the composition containing the zirconium oxide nanoparticles of the invention is fired at 500 ° C. or higher is also included in the present invention.

  According to the invention, the zirconium oxide nanoparticles coated with a coating agent are selected from the group consisting of La, Ce, Eu, Fe, Co, Sn, Zn, In, Bi, Mn, Ni and Cu. Zirconium oxide nanoparticles containing at least one kind can be provided.

FIG. 1 is an X-ray diffraction chart of lanthanum-containing zirconia nanoparticles. FIG. 2 is an X-ray diffraction chart of tin-containing zirconia nanoparticles. FIG. 3 is an X-ray diffraction chart of zinc-containing zirconia nanoparticles. FIG. 4 is an X-ray diffraction chart of cerium-containing zirconia nanoparticles. FIG. 5 is an X-ray diffraction chart of indium-containing zirconia nanoparticles. FIG. 6 is an X-ray diffraction chart of bismuth-containing zirconia nanoparticles. FIG. 7 is an X-ray diffraction chart of iron-containing zirconia nanoparticles. FIG. 8A is an X-ray diffraction chart of europium-containing zirconia nanoparticles. FIG. 8B is an X-ray diffraction chart of europium-containing zirconia nanoparticles. FIG. 8C is an X-ray diffraction chart of europium-containing zirconia nanoparticles.

  Since the zirconium oxide nanoparticles (zirconia nanoparticles) of the present invention are coated with a carboxylic acid having 3 or more carbon atoms, the dispersibility is good (including dispersibility in organic media such as solvents and resins). In addition, since the ceramic material obtained by firing the zirconium oxide nanoparticles of the present invention has a uniform particle size, the ceramic properties such as translucency, toughness and strength are good.

  The carboxylic acid covering the zirconium oxide nanoparticles of the present invention (hereinafter referred to as the first carboxylic acid) has 3 or more carbon atoms, preferably 4 or more, more preferably 5 or more. Although the upper limit of carbon number is not specifically limited, For example, it is 22 or less, Preferably it is 20 or less, More preferably, it is 18 or less. The first carboxylic acid may be any of primary carboxylic acid, secondary carboxylic acid, and tertiary carboxylic acid.

  Examples of the primary carboxylic acid include linear primary carboxylic acid and branched primary carboxylic acid (that is, carboxylic acid in which carbon atoms other than α-position are branched), and among them, the number of carbon atoms is 4 or more (more preferably 5 or more, more preferably 8 or more) 20 or less linear carboxylic acid, and carboxylic acid in which carbon atoms other than α-position are branched are preferable. The linear carboxylic acid having 4 to 20 carbon atoms is preferably a linear saturated aliphatic carboxylic acid, specifically, butyric acid, valeric acid, hexanoic acid, heptanoic acid, caprylic acid, nonanoic acid. , Decanoic acid, lauric acid, tetradecanoic acid, stearic acid, oleic acid, ricinoleic acid and the like, preferably caprylic acid, lauric acid, stearic acid, oleic acid, ricinoleic acid. The carboxylic acid having a branched carbon atom other than the α-position means a carboxylic acid having a carboxyl group bonded to a hydrocarbon group and having a branched carbon atom other than the α-position of the hydrocarbon group. Such carboxylic acid preferably has 4 to 20 carbon atoms, more preferably 5 to 18 carbon atoms, such as isovaleric acid, 3,3-dimethylbutyric acid, 3-methylvaleric acid, isononanoic acid, 4-methylvaleric acid. 4-methyl-n-octanoic acid, naphthenic acid and the like.

  The secondary carboxylic acid is preferably a secondary carboxylic acid having 4 to 20 carbon atoms, more preferably a secondary carboxylic acid having 5 to 18 carbon atoms, specifically isobutyric acid, 2-methylbutyric acid, 2-ethylbutyric acid. 2-ethylhexanoic acid, 2-methylvaleric acid, 2-methylhexanoic acid, 2-methylheptanoic acid, 2-propylbutyric acid, 2-hexylvaleric acid, 2-hexyldecanoic acid, 2-heptylundecanoic acid, 2-methyl Examples include hexadecanoic acid and 4-methylcyclohexanecarboxylic acid. Among these, at least one of 2-ethylhexanoic acid and 2-hexyldecanoic acid is preferable, and 2-ethylhexanoic acid is particularly preferable.

  As the tertiary carboxylic acid, a tertiary carboxylic acid having 5 to 20 carbon atoms is preferable. Specifically, pivalic acid, 2,2-dimethylbutyric acid, 2,2-dimethylvaleric acid, 2,2-dimethylhexanoic acid, Examples include 2,2-dimethylheptanoic acid and neodecanoic acid.

  As the first carboxylic acid, one or more of a primary carboxylic acid and a secondary carboxylic acid are preferable, a carboxylic acid having a branched carbon atom other than the α-position, a linear carboxylic acid having 4 to 20 carbon atoms, and 2 It is preferable that it is 1 or more types of secondary carboxylic acid. Of these, the first carboxylic acid is preferably at least one of a carboxylic acid having a branched carbon atom other than the α-position and a secondary carboxylic acid, more preferably a secondary carboxylic acid.

  The amount of the first carboxylic acid is, for example, 5 to 40% by mass (preferably 8 to 35% by mass, more preferably 10 to 30% by mass) based on the zirconium oxide nanoparticles coated with the first carboxylic acid. %). When the zirconium oxide nanoparticles of the present invention are further coated with an organic acid other than the first carboxylic acid described later, the total amount of the first carboxylic acid and the organic acid other than the first carboxylic acid is as described above. If it is in the range of

  Note that the zirconium oxide nanoparticles of the present invention are coated with the first carboxylic acid means that the first carboxylic acid is chemically bonded to the zirconium oxide nanoparticles or physically bonded. Meaning that it is coated with the first carboxylic acid and / or the carboxylate derived from the first carboxylic acid.

  In the present invention, the zirconium oxide nanoparticles are coated with the first carboxylic acid described above, and from the group consisting of La, Ce, Eu, Fe, Co, Sn, Zn, In, Bi, Mn, Ni, and Cu. It contains at least one selected metal element (hereinafter, these may be collectively referred to as “second metal”). However, the zirconium oxide nanoparticles of the present invention do not contain yttrium. The total content of the second metal is preferably 0.1% by mass or more, more preferably 1% by mass or more, and more preferably 40% by mass or less, in terms of the ratio to the total content of the second metal and zirconium. Is 30% by mass or less, more preferably 20% by mass or less, and still more preferably 15% by mass or less.

More specifically, the content of La is preferably 0.1% by mass or more, more preferably 1% by mass or more, and preferably 40% by mass or less, more preferably 30%, based on the total of La and zirconium. It is not more than mass%, more preferably not more than 20 mass%, and still more preferably not more than 15 mass%.
The Ce content is preferably 0.1% by mass or more, more preferably 1% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, based on the total of Ce and zirconium. More preferably, it is 20 mass% or less, More preferably, it is 15 mass% or less.
The content of Eu is preferably 0.1 to 40% by mass, more preferably 1 to 30% by mass with respect to the total of Eu and zirconium.
The content of Fe is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass with respect to the total of Fe and zirconium.
The content of Co is preferably 0.1 to 20% by mass, more preferably 1 to 15% by mass with respect to the total of Co and zirconium.
The content of Sn is preferably 0.1 to 20% by mass, more preferably 1 to 15% by mass with respect to the total of Sn and zirconium.
The content of Zn is preferably 0.1 to 20% by mass, more preferably 1 to 15% by mass with respect to the total of Zn and zirconium.
The content of In is preferably 0.1 to 20% by mass, more preferably 1 to 15% by mass with respect to the total of In and zirconium.
The content of Bi is preferably 0.1 to 20% by mass, more preferably 1 to 15% by mass with respect to the total of Bi and zirconium.
The content of Mn is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass with respect to the total of Mn and zirconium.
The content of Ni is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass with respect to the total of Ni and zirconium.
The content of Cu is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass with respect to the total of Cu and zirconium.

  The second metal in the present invention exists as a complex oxide of zirconium and the second metal in the zirconium oxide nanoparticles. Among these second metals, in particular, lanthanum, cerium, europium and indium are complex oxides of zirconium and the second metal (in this case, lanthanum, cerium, europium or indium) even after firing described later. It exists and has the effect of stabilizing tetragonal or cubic zirconium oxide. In particular, when the content of the second metal is about 10% by mass or less, the composite oxide is stabilized as a tetragonal crystal, and when the content exceeds 10% by mass, the composite oxide is cubic. There is a tendency to stabilize as crystals.

  The proportion of zirconium contained in the zirconium oxide nanoparticles of the present invention is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably, based on the total of all metal elements contained in the zirconium nanoparticles. It is 70 mass% or more, More preferably, it is 73 mass% or more, Most preferably, it is 75 mass% or more. Further, as the metal element contained in the zirconium oxide nanoparticles of the present invention, other metal elements other than La, Ce, Eu, Fe, Co, Sn, Zn, In, Bi, Mn, Ni and Cu described above are included. (However, yttrium is not included.) Such other metal element is usually a metal element of Group 3 or later of the periodic table. The total amount of other metal elements is, for example, 5% by mass or less, more preferably 2% by mass or less, or 0% by mass with respect to the total of all metal elements contained in the zirconium nanoparticles. .

  The crystal structure of the zirconium oxide nanoparticles of the present invention is preferably at least one of cubic, tetragonal and monoclinic.

  Examples of the shape of the zirconium oxide nanoparticles include a spherical shape, a granular shape, an elliptical spherical shape, a cubic shape, a rectangular parallelepiped shape, a pyramid shape, a needle shape, a column shape, a rod shape, a cylindrical shape, a flake shape, a plate shape, and a flake shape. Considering the dispersibility in a solvent and the physical strength after sintering, the shape is preferably spherical, granular, columnar or the like.

  The crystallite size of the zirconium oxide nanoparticles calculated by X-ray diffraction analysis is preferably 30 nm or less. By doing in this way, the transparency of the composition containing a zirconium oxide nanoparticle can be improved. In addition, the particles can be expected to reduce the firing temperature and improve the transparency of the fired body. The crystallite diameter is more preferably 20 nm or less, and further preferably 15 nm or less. The lower limit of the crystallite diameter is usually about 1 nm.

  The particle diameter of the zirconium oxide nanoparticles can be evaluated by an average particle diameter obtained by processing images obtained by various electron microscopes, and the average particle diameter (average primary particle diameter) is preferably 50 nm or less. By doing in this way, the transparency of the composition containing a zirconium oxide nanoparticle can be improved. The average primary particle diameter is more preferably 30 nm or less, and further preferably 20 nm or less. The lower limit of the average primary particle size is usually about 1 nm (particularly about 5 nm).

  The average particle size is randomly increased by expanding the zirconium oxide nanoparticles with a transmission electron microscope (TEM), a field emission transmission electron microscope (FE-TEM), a field emission scanning electron microscope (FE-SEM), and the like. It can be determined by selecting 100 particles, measuring the length in the major axis direction, and calculating the arithmetic average thereof.

  The zirconium oxide nanoparticles of the present invention are obtained by coating the first carboxylic acid obtained after the hydrothermal synthesis reaction with an organic material other than the first carboxylic acid by subjecting the surface treatment to room temperature or heating. The surface may be modified with an acid, a silane coupling agent, a surfactant, an organic phosphorus compound, or the like. By subjecting the first obtained nanoparticles to surface treatment again, it becomes possible to control the mixing property with other substances, the moldability, etc., and it can be applied to various uses. Preferred organic acids, silane coupling agents, surfactants and organophosphorus compounds are described below.

<Organic acid>
As the organic acid, a carboxylic acid compound having a carboxyl group other than the first carboxylic acid is preferably used. Since the carboxylic acid compound is chemically bonded to the zirconium oxide nanoparticles or forms a carboxylic acid or a salt thereof together with a hydrogen atom or a cationic atom and adheres to the zirconium oxide nanoparticles, the term “coating” in the present invention refers to a carboxylic acid compound. It includes both the state in which the acid compound is chemically bonded to zirconium oxide and the state in which the carboxylic acid compound is physically attached to zirconium oxide.

  The carboxylic acid compound having a carboxyl group other than the first carboxylic acid can be freely selected depending on the dispersibility in the solvent and the properties of the material other than the zirconium oxide nanoparticles, but (meth) acrylic acids and esters A carboxylic acid having at least one substituent selected from the group consisting of a group, an ether group, a hydroxyl group, an amino group, an amide group, a thioester group, a thioether group, a carbonate group, a urethane group, and a urea group; Hydrocarbons having one or more (preferably one) carboxylic acid groups such as linear carboxylic acid, branched carboxylic acid, cyclic carboxylic acid or aromatic carboxylic acid are preferably employed.

Specific examples of such carboxylic acid compounds include (meth) acrylic acids (for example, (meth) acryloyloxy C _1-6 alkyl carboxylic acids such as acrylic acid, methacrylic acid, 3-acryloyloxypropionic acid, etc.); C Half esters of _3-9 aliphatic dicarboxylic acid with (meth) acryloyloxy C _1-6 alkyl alcohol (for example, 2-acryloyloxyethyl succinic acid, 2-methacryloyloxyethyl succinic acid, etc.), C _5-10 fatty acid Half esters of cyclic dicarboxylic acid with (meth) acryloyloxy C _1-6 alkyl alcohol (for example, 2-acryloyloxyethyl hexahydrophthalic acid, 2-methacryloyloxyethyl hexahydrophthalic acid, etc.), C _8-14 aromatic dicarboxylic acids (meth) acryloyloxy C _1-6 half by alkyl alcohol Carboxylic acids having ester groups such as stealth (for example, 2-acryloyloxyethylphthalic acid, 2-methacryloyloxyethylphthalic acid, etc.); pivalic acid, 2,2-dimethylbutyric acid, 2,2-dimethylvaleric acid Branched carboxylic acids such as 2,2-diethylbutyric acid and neodecanoic acid; cyclic carboxylic acids such as naphthenic acid and cyclohexanedicarboxylic acid; carboxylic acids containing ether groups (methoxyacetic acid, ethoxyacetic acid, etc.); containing hydroxyl groups Carboxylic acids (such as lactic acid and hydroxypropionic acid), carboxylic acids having an amino group (such as amino acids such as glycine, alanine, and cysteine).

<Silane coupling agent>
As the silane coupling agent, a compound having a hydrolyzable group —Si—OR ₁ (where R ₁ is a methyl group or an ethyl group) is preferable. As such a silane coupling agent, a silane coupling agent having a functional group, an alkoxysilane, and the like can be exemplified.

As a silane coupling agent having a functional group, the following formula (1):
_{[X- (CH 2) m]} 4-n -Si- (OR 1) n ... (1)
(Wherein, X is a functional group, R ₁ is the same as described above, m is an integer of 0 to 4, and n is an integer of 1 to 3).

  Examples of X include a vinyl group, an amino group, a (meth) acryloxy group, a mercapto group, and a glycidoxy group. Specific examples of the silane coupling agent include, for example, a silane coupling agent having a vinyl functional group X such as vinyltrimethoxysilane and vinyltriethoxysilane; 3-aminopropyltrimethoxysilane, 3-aminopropyltri Silane coupling in which the functional group X is an amino group such as ethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyltrimethoxysilane Agent: Functionality such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane Group X is (meta Silane coupling agent which is acryloxy group; Silane coupling agent whose functional group X is mercapto group such as 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane; 2- (3,4-epoxycyclohexyl) ethyl Functional groups X such as trimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane And a silane coupling agent which is a glycidoxy group.

  Examples of the alkoxysilane include methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, propyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, decyltrimethoxy. Alkyl group-containing alkoxysilane in which an alkyl group such as silane is directly bonded to the silicon atom of alkoxysilane; an aromatic ring such as phenyltrimethoxysilane, diphenyldimethoxysilane, p-styryltrimethoxysilane, etc. directly on the silicon atom of alkoxysilane And aryl group-containing alkoxysilanes bonded to each other.

  As the silane coupling agent, a silane coupling agent in which the functional group X is a (meth) acryloxy group and an alkyl group-containing alkoxysilane are preferable, and 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyl are particularly preferable. Trimethoxysilane, hexyltrimethoxysilane, octyltriethoxysilane, and decyltrimethoxysilane.

  The silane coupling agent may be used alone or in combination of two or more. The amount of silane coupling agent (covering amount) is preferably 0.1 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the entire zirconium oxide nanoparticles.

<Surfactant>
The surfactant can improve the transparency and dispersibility of the composition. Furthermore, the viscosity of the composition can be reduced. As the surfactant, an anionic surfactant, a cationic surfactant, an ionic surfactant such as an amphoteric surfactant, or a nonionic surfactant is preferably used. Examples of the activator include fatty acid sodium such as sodium oleate, sodium stearate and sodium laurate, fatty acid potassium such as fatty acid potassium and sodium fatty acid ester sulfonate, phosphoric acid such as sodium alkyl phosphate ester, and alpha olein sulfone. Examples of cation surfactants include olefins such as sodium acid, alcohols such as sodium alkyl sulfate, and alkylbenzenes. Examples of the cationic surfactant include alkyl methyl ammonium chloride, alkyl dimethyl ammonium chloride, alkyl trimethyl ammonium chloride, and alkyl dichloride. Examples of the zwitterionic ammonium include zwitterionic surfactants such as carboxylic acid-based surfactants such as alkylaminocarboxylates, and phosphoric ester-based surfactants such as phosphobetaine. Examples include fatty acid series such as oxyethylene laurin fatty acid ester and polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, and fatty acid alkanolamide. The surfactant is preferably added in an amount of 0.1% by mass to 5% by mass with respect to 100% by mass of all components of the composition.

<Organic phosphorus compounds>
As an organic phosphorus compound, for example, the following formula:

(In the above formula, each of p ¹ and p ² is preferably 1 to 100, more preferably 1 to 50, still more preferably 1 to 30, particularly preferably 4 to 15. Moreover, p ¹ + p ² is preferably 1 to 100, more preferably 1 to 50, and still more preferably 1 to 30), and phosphoric acid diesters having the same substituents. It is done.

  Also the following formula:

[In the above formula, a is 1 or 2, and A is a substituent group represented by the following formula:

(In the above formula, each of p ¹ , p ² and p ⁵ is preferably 1 to 100, more preferably 1 to 50, still more preferably 1 to 30, more preferably 4 to 15.) p ¹ + p ² + p ⁵ is preferably 1 to 100, more preferably 1 to 50, still more preferably 1 to 30. r and r ² are preferably 1 to 100, more preferably 1 to 50. More preferably 1 to 20. R ⁴ is a divalent hydrocarbon group having 1 to 18 carbon atoms or a divalent aromatic-containing hydrocarbon group having 6 to 30 carbon atoms, where * is a phosphorus atom Or at least one selected from the group consisting of a phosphoric acid monoester and a phosphoric acid diester, and the following formula:

[In the above formula, a is 1 or 2, and A is a substituent group represented by the following formula:

(Wherein p ¹ is preferably ¹ to 100, more preferably 1 to 50, and still more preferably 1 to 30). formula:

(Wherein p ¹ is preferably ¹ to 100, more preferably 1 to 50, and still more preferably 1 to 30), or the following formula:

The various phosphoric acid compounds or phosphate ester represented by these can be illustrated.

  In the present invention, two or more organic phosphorus compounds having different structures such as phosphoric acid monoesters and phosphoric acid diesters or salts thereof may be used alone or in combination.

  Examples of the organophosphorus compounds described above include Newcol 1000-FCP (manufactured by Nippon Emulsifier Co., Ltd.), Antox EHD-400 (manufactured by Nippon Emulsifier Co., Ltd.), Phoslex series (manufactured by SC Organic Chemical Co., Ltd.), light acrylate P-1A Kyoeisha Chemical Co., Ltd.), Light Acrylate P-1M (Kyoeisha Chemical Co., Ltd.), TEGO (registered trademark) Dispers 651, 655, 656 (Evonik Co., Ltd.), DISPERBYK-110, 111 (Bicchemy Japan Co., Ltd.), KAYAMERPM-2 Commercially available phosphate esters such as KAYAMERPM-21 (manufactured by Nippon Kayaku Co., Ltd.) can be used as appropriate.

  The amount of the organic phosphorus compound is about 0.5 to 10 parts by mass with respect to 100 parts by mass of the zirconium oxide nanoparticle-containing composition of the present invention.

  The zirconium oxide nanoparticles of the present invention are coated with the first carboxylic acid by hydrothermal reaction of the zirconium component, the second metal component, and the first carboxylic acid component. Zirconium oxide nanoparticles can be obtained. As the zirconium component, a zirconium raw material composed of (preferably combined) a first carboxylic acid and zirconium or a zirconium-containing compound can be used. Such a zirconium raw material is a first carboxylic acid. It can also be said to be an ingredient. In addition, as the second metal component, it is possible to use a source material of a second metal composed of a first carboxylic acid and a second metal or a second metal-containing compound (preferably a conjugate). Such a second metal source material can also be said to be the first carboxylic acid component. At this time, the first carboxylic acid contained in the zirconium component and the second metal component may be the same or different, and a plurality of types may be used.

  Specific examples of the zirconium raw material include (i) a salt of a first carboxylic acid and a zirconium oxide precursor, (ii) a zirconium salt of the first carboxylic acid, and (iii) a first carboxylic acid and an oxidation. Examples thereof include at least one selected from zirconium precursors.

  Examples of the zirconium oxide precursor include zirconium hydroxide, chloride, oxychloride, acetate, oxyacetate, oxynitrate, sulfate, carbonate, alkoxide and the like. That is, zirconium alkoxides such as zirconium hydroxide, zirconium chloride, zirconium oxychloride, zirconium acetate, zirconium oxyacetate, zirconium oxynitrate, zirconium sulfate, zirconium carbonate, and tetrabutoxyzirconium.

  Hereinafter, as the zirconium oxide precursor, a zirconium oxide precursor such as oxychloride of zirconium and nitrates such as oxynitrate, which is suitable for use as a raw material, a zirconium oxide precursor that is highly water-soluble and corrosive is preferable ( The case of i) will be described in detail. The salt is not only a single compound composed of a stoichiometric ratio of carboxylic acid and zirconium oxide precursor, but also a composite salt or a composition containing an unreacted carboxylic acid or zirconium oxide precursor. There may be.

  In the above (i), the salt of the first carboxylic acid and the zirconium oxide precursor was neutralized with an alkali metal and / or alkaline earth metal in a range of 0.1 to 0.8. A salt of the first carboxylic acid and zirconium obtained by reacting the carboxylate-containing composition derived from the first carboxylic acid with the zirconium oxide precursor is preferable.

  The neutralization degree is preferably 0.1 to 0.8, and more preferably 0.2 to 0.7. If it is less than 0.1, the first carboxylic acid compound has low solubility, so that the salt may not be sufficiently formed. If it exceeds 0.8, a large amount of white precipitate presumed to be a hydroxide of zirconium is formed. In some cases, the yield of the coated zirconium oxide nanoparticles decreases. The alkali metal and alkaline earth metal used to obtain the carboxylate-containing composition may be any, but a metal that forms a highly water-soluble carboxylate is preferable, and alkali metals, particularly sodium and potassium are preferred. Is preferred.

  The ratio of the carboxylate-containing composition and the zirconium oxide precursor is preferably 1 mol to 20 mol, more preferably 1.2 to 18 mol of the carboxyl group with respect to 1 mol of the zirconium oxide precursor. 1.5 to 15 mol is more preferable. In order to react the carboxylate-containing composition with the zirconium oxide precursor, it is preferable to mix aqueous solutions or an aqueous solution and an organic solvent. The reaction temperature is not particularly limited as long as the aqueous solution can be maintained, but is preferably from room temperature to 100 ° C, more preferably from 40 ° C to 80 ° C.

  The salt obtained by reacting the carboxylate-containing composition with the zirconium oxide precursor may be subjected to a hydrothermal reaction as it is, but insoluble by-products are removed by filtration, liquid separation, or the like. Is preferred.

  Next, the case (ii) will be described in detail. In the embodiment (ii), a zirconium salt of the first carboxylic acid prepared in advance is used. There is an advantage that it can be subjected to a hydrothermal reaction without going through the complicated steps as described above. However, since compounds that can be easily obtained are limited, zirconium oxide nanoparticles coated with the target organic group may not be obtained.

  Examples of the zirconium salt that can be used in the embodiment of (ii) include zirconium octoate, zirconium 2-ethylhexanoate, zirconium stearate, zirconium laurate, zirconium naphthenate, zirconium oleate, zirconium ricinoleate and the like. I can do it. When the purity of the zirconium salt is low, it may be used after purification, but a commercially available product or a salt prepared in advance can be directly subjected to a hydrothermal reaction.

The said zirconium oxide precursor which can be used by said (iii) is the same as the zirconium oxide precursor mentioned above. In the case of (iii), the zirconium oxide precursor is preferably zirconium carbonate. The ratio of the carboxylic acid to the zirconium oxide precursor is preferably 0.5 mol to 10 mol, more preferably 1 mol to 8 mol, based on 1 mol of the zirconium oxide precursor. Preferably, it is 1.2 mol-5 mol. The carboxylic acid and the zirconium oxide precursor may be subjected to a hydrothermal reaction as they are, or may be reacted in advance before the hydrothermal reaction. In order to make it react before a hydrothermal reaction, it is preferable to make carboxylic acid and a zirconium oxide precursor react in a slurry in an organic solvent. At that time, it is preferable to carry out the reaction while removing water produced during the reaction, also in terms of improving the reaction rate and yield. In order to perform the reaction while extracting water during the reaction, it is preferable to use a solvent having a boiling point higher than that of water as the reaction solvent, and more preferably a solvent used in the hydrothermal reaction described later. Moreover, 70 degreeC or more is preferable and, as for reaction temperature, 80 degreeC or more is more preferable so that water can be extracted. The upper limit of the reaction temperature is preferably 180 ° C. or lower, and more preferably 150 ° C. or lower. If the temperature is too high, side reactions may proceed and decomposition of the carboxylic acid may occur. If water cannot be taken out during the reaction, the reaction can be carried out by lowering the reaction pressure to lower the boiling point of water.

  Specifically, as the second metal source material, (i) a salt of a first carboxylic acid and an oxide precursor of the second metal, (ii) a second metal of the first carboxylic acid And (iii) a first carboxylic acid and an oxide precursor of a second metal. The preferred embodiments (i) to (iii) are the same as the preferred embodiments (i) to (iii) in the zirconium raw material.

  Subsequently, the hydrothermal reaction will be described. First, at least one of the above (i) to (iii) for the zirconium component and at least one of the above (i) to (iii) for the second metal component are preferably mixed in the presence of water. At this time, by performing under heating or under reduced pressure, low boiling point compounds contained in the zirconium oxide precursor such as ammonia and acetic acid can be driven out of the system, and the pressure increase in the hydrothermal reaction in the next step is suppressed. Therefore, it is preferable. When the viscosity is high and the hydrothermal reaction does not proceed efficiently only with the above (i) to (iii), it is preferable to add an organic solvent exhibiting good solubility for the above (i) to (iii). . In order to obtain the zirconium oxide nanoparticles of the present invention, the zirconium salt of the first carboxylic acid and the salt of the second metal of the first carboxylic acid are used as the zirconium component and the second metal component, respectively. It is preferable to use the mode (ii) for both the zirconium component and the second metal component. However, when there is at least one component that is difficult to use the embodiment (ii) for the zirconium component and the second metal component, of course, the component used in the embodiment (i) or (iii) may be present. In such a case, the aspects of the raw material used as the zirconium component and the second metal component include (ii) and (i) only, (ii) and (iii) only, (i) only, (iii) It is preferable that it is only either. When both the zirconium component and the second metal component are used in the form (iii), the zirconium oxide precursor, the second metal oxide precursor and the first carboxylic acid are mixed before the hydrothermal reaction. Thus, a raw material containing both zirconium and the second metal may be synthesized in advance, and in this way, the number of synthesis steps can be reduced.

  As the organic solvent, hydrocarbons, ketones, ethers, alcohols and the like can be used. Since there is a possibility that the reaction does not proceed sufficiently with a solvent that is vaporized during a hydrothermal reaction, an organic solvent having a boiling point of 120 ° C. or higher under normal pressure is preferable, 140 ° C. or higher is more preferable, and 150 ° C. or higher is even more preferable. Specifically, decane, dodecane, tetradecane, mesitylene, pseudocumene, mineral oil, octanol, decanol, cyclohexanol, terpineol, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butane Examples include diol, 2,3-butanediol, hexanediol, glycerin, methanetrimethylol, toluene, xylene, trimethylbenzene, dimethylformamide (DMF), dimethylsulfoxide (DMSO) and the like, and dodecane, tetradecane, and trimethylbenzene are preferable.

  When separated into two layers by adding the organic solvent, a surfactant or the like may be added to obtain a homogeneous phase state or a suspension emulsified state, but usually the two layers are subjected to a hydrothermal reaction. I can do it. The composition may contain a sufficient amount of water derived from the raw material, but if there is no or little water contained in the raw material, add water before subjecting it to a hydrothermal reaction. There is a need.

  The amount of water present in the hydrothermal reaction system is the number of moles of water relative to the number of moles of zirconium in the zirconium oxide precursor or zirconium-containing salt (hereinafter referred to as zirconium oxide precursor) present in the system. 1/1 to 50/1 is preferable and 4/1 to 30/1 is more preferable in terms of the number of moles / the number of moles of zirconium in the zirconium oxide precursor. If it is less than 1/1, the hydrothermal reaction may take a long time, and the obtained zirconium oxide nanoparticles may have a large particle size. On the other hand, if it exceeds 50/1, there is no particular problem except that productivity is lowered because there are few zirconium oxide precursors or the like present in the system.

  The hydrothermal reaction is preferably performed at a pressure of 2 MPaG (gauge pressure) or less. Although the reaction proceeds even above 2 MPaG, the reaction apparatus becomes expensive, which is not industrially preferable. On the other hand, if the pressure is too low, the reaction progresses slowly, and the particle size of the nanoparticles may increase due to the long-time reaction or the zirconium oxide may have a plurality of crystal systems. It is preferable to carry out under the above pressure, and it is more preferable to carry out at 0.2 MPaG or more. The temperature of the hydrothermal reaction is, for example, 150 to 250 ° C., and the temperature may be maintained, for example, for about 2 to 24 hours.

  When the zirconium oxide nanoparticles of the present invention are coated with the first carboxylic acid and an organic acid other than the first carboxylic acid, first, the zirconium oxide nanoparticles coated with the first carboxylic acid are firstly coated. It can be produced by preparing particles and then substituting the first carboxylic acid compound with the organic acid. Specifically, this substitution is performed by stirring a mixture (particularly a mixed solution) containing zirconium oxide nanoparticles coated with the first carboxylic acid and an organic acid. The mass ratio between the organic acid and the zirconium oxide nanoparticles coated with the first carboxylic acid is preferably 5/100 to 200/100.

  Since the zirconium oxide nanoparticles of the present invention have good dispersibility in various media, they can be added to various solvents, monomers (monofunctional monomers and / or crosslinkable monomers), oligomers, polymers, etc., or combinations thereof. Is possible. The zirconium oxide nanoparticles of the present invention can also be suitably used as a composition containing them. The composition includes a dispersion containing zirconium oxide nanoparticles and a resin composition containing zirconium oxide nanoparticles.

  Representative solvents include, for example, alcohols such as methanol, ethanol, n-propanol, isopropanol, and ethylene glycol; ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ethyl acetate, propyl acetate, propylene glycol monomethyl ether acetate, and the like Esters such as ethylene glycol monomethyl ether and diethylene glycol monobutyl ether; modified ethers such as propylene glycol monomethyl ether acetate (preferably ether-modified and / or ester-modified ethers, more preferably ether-modified and / or ester-modified) Alkylene glycols); benzene, toluene, xylene, ethylbenzene, trimethylbenzene, hexane Hydrocarbons such as cyclohexane, methylcyclohexane, ethylcyclohexane and mineral spirits; Halogenated hydrocarbons such as dichloromethane and chloroform; Amides such as dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone; Water; Mineral oil And oils such as vegetable oils, wax oils, and silicone oils. One of these can be selected and used, or two or more can be selected and mixed for use. From the viewpoint of handleability, a solvent having a boiling point of 40 ° C. or more and 250 ° C. or less at normal pressure is suitable, and ketones, modified ethers and the like are suitable for resist applications described later.

  The monofunctional monomer may be a compound having only one polymerizable carbon-carbon double bond, and is a (meth) acrylic ester; styrene, p-tert-butylstyrene, α-methylstyrene, m-methylstyrene. , Styrene monomers such as p-methylstyrene, p-chlorostyrene, and p-chloromethylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid; hydroxyl group-containing monomers such as hydroxyethyl (meth) acrylate Examples include the body. Specific examples of the (meth) acrylic acid ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth). (Meth) acrylic acid alkyl esters such as acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and lauryl (meth) acrylate; (meth) acrylic such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate Acid cycloalkyl ester; Aralkyl (meth) acrylate such as benzyl (meth) acrylate; (Meth) acrylate ester having glycidyl group such as glycidyl (meth) acrylate, etc., but methyl (meth) acrylate is Preferred. These exemplified monofunctional monomers may be used alone, or two or more kinds may be appropriately mixed and used.

  The crosslinkable monomer may be a compound containing a plurality of carbon-carbon double bonds copolymerizable with the carbon-carbon double bond of the monomer. Specific examples of the crosslinkable monomer include alkylene glycol poly (ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate) and the like. (Meth) acrylate; neopentyl glycol poly (meth) acrylate such as neopentyl glycol di (meth) acrylate and dineopentyl glycol di (meth) acrylate; trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) Trimethylolpropane poly (meth) acrylates such as acrylates; pentaerythritol tetra (meth) acrylates, dipentaerythritol hexa (meth) acrylates and other Polyfunctional (meth) acrylates such as taerythritol poly (meth) acrylate; polyfunctional styrene monomers such as divinylbenzene; polyfunctional allyl esters such as diallyl phthalate, diallyl isophthalate, triallyl cyanurate, triallyl isocyanurate System monomers and the like.

  The composition containing the monomer corresponds to a curable composition. The curable composition constitutes a resin composition after curing, and such a curable composition is also included in the resin composition of the present invention. The composition of the present invention may be a resin composition containing the polymer (resin). In the case of constituting the resin composition of the present invention, the polymer that is a medium is, for example, polyamides such as 6-nylon, 66-nylon, and 12-nylon; polyimides; polyurethanes; polyolefins such as polyethylene and polypropylene, PET Polyesters such as PBT, PBT, PEN; Polyvinyl chlorides; Polyvinylidene chlorides; Polyvinyl acetates; Polystyrenes; (Meth) acrylic resin-based polymers; ABS resins; Fluorine resins; Phenol / formalin resins, Cresol / formalin resins Phenolic resins such as: epoxy resins; amino resins such as urea resins, melamine resins, and guanamine resins. Moreover, soft resins and hard resins such as polyvinyl butyral resins, polyurethane resins, ethylene-vinyl acetate copolymer resins, and ethylene- (meth) acrylate copolymer resins are also included. Among the above, polyimides, polyurethanes, polyesters, (meth) acrylic resin polymers, phenol resins, amino resins, and epoxy resins are more preferable. These may be used alone or in combination of two or more.

  The concentration of the zirconium oxide nanoparticles of the present invention in the composition can be appropriately set according to the use. However, when the composition is uncured or contains a polymer (resin), the composition is usually used. It is 90 mass% or less with respect to 100 mass% of all the components (the total of what is used among substitution covering type particle | grains, a solvent, a monomer, an oligomer, a polymer, and the polymer precursor mentioned later). If it exceeds 90% by mass, it may be difficult to disperse uniformly and the transparency may be lowered by the uncured composition. On the other hand, the lower limit is not particularly limited, but is, for example, 1% by mass or more in consideration of the solvent cost. More preferably, they are 5 mass% or more and 85 mass% or less, More preferably, they are 10 mass% or more and 80 mass% or less.

  In addition, the resin composition of the present invention includes not only the composition of the polymer (polymer compound) and the zirconium oxide nanoparticles of the present invention, but also a monomer (polymer precursor) constituting the polymer, for example, Also included are compositions of a mixture of dicarboxylic acid and diamine, unsaturated carboxylic acid such as acrylic acid and methacrylic acid, its ester compound, and the like, and the zirconium oxide nanoparticles of the present invention. The resin composition of the present invention may be one containing both a polymer and a monomer, one containing a polymer and a solvent (coating material), or a molding resin used for a molding material such as an optical film. Also good.

  In addition, since the zirconium oxide nanoparticles of the present invention are remarkably excellent in dispersibility, the composition has good transparency even in the case of a high concentration composition (dispersion). A composition in which zirconium oxide nanoparticles are dispersed at a high concentration is advantageous, for example, in improving the refractive index, and the refractive index can be adjusted according to various applications. When used as a high-concentration zirconium oxide nanoparticle composition, the amount of zirconium oxide nanoparticles in the composition is preferably 25% by mass or more, more preferably 30% by mass or more, and still more preferably Is 60% by mass or more. Although the upper limit is not particularly limited, the amount of zirconium oxide nanoparticles in the composition is preferably 90% by mass or less.

  The resin composition (including the cured curable composition) of the present invention may contain zirconium oxide nanoparticles and other additive components of the resin. Examples of the additive component include a curing agent, a curing accelerator, a colorant, a release agent, a reactive diluent, a plasticizer, a stabilizer, a flame retardant aid, and a crosslinking agent. In addition, this nanoparticle can be colored by adding a suitable transition metal, and can also change a color eye by changing the kind and quantity of a transition metal according to a use.

  The shape of the resin composition (including the curable composition after curing) of the present invention is not particularly limited, and may be a molding material such as a plate, a sheet, a film, or a fiber.

  Zirconium oxide nanoparticles of the present invention have good dispersibility, such as antireflection films, hard coat films, brightness enhancement films, prism films, lenticular sheets, microlens sheets, and other optical films (or sheets), and optical refractive indices. Conditioner, optical adhesive, optical waveguide, lens, catalyst, CMP polishing composition, electrode, capacitor, ink jet recording method, piezoelectric element, LED / OLED / organic EL light extraction improver, antibacterial agent, dental It is suitably used for adhesives, condensing structures used in solar cell panels, color filters, and fluorescent materials.

  The present invention also includes a ceramic material obtained from the zirconium oxide nanoparticles of the present invention (zirconium oxide nanoparticles coated with a first carboxylic acid and containing a second metal).

  The ceramic material obtained from the zirconium oxide nanoparticles of the present invention can be obtained by firing the zirconium oxide nanoparticles of the present invention alone. Further, the zirconium oxide nanoparticles of the present invention can be obtained by firing a composition containing additives such as alumina, spinel, YAG, mullite, and an aluminum borate compound. Furthermore, the composition which consists of a zirconium oxide nanoparticle of this invention and a binder can also be obtained by baking. The firing temperature at this time may be about 500 to 1600 ° C. Firing can be performed by a known method. Pressure may be applied to promote sintering during firing. Further, it may be fired in air, an oxygen atmosphere, a mixed atmosphere of oxygen and air, or may be fired in an inert atmosphere such as nitrogen or argon. Each can be appropriately selected according to the use after firing.

  Since the zirconium oxide nanoparticles of the present invention exhibit good dispersibility, the ceramic material obtained from the zirconium oxide nanoparticles of the present invention has good ceramic properties such as translucency, toughness and strength.

  The ceramic material obtained from the zirconium oxide nanoparticles of the present invention contains a complex oxide of usually added metal and zirconium, a mixture of each single oxide, or both.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited by the following examples, and can of course be implemented with appropriate modifications within a range that can be adapted to the above-described gist. Included in the range.

  The physical properties and characteristics disclosed in the examples were measured by the following methods.

(1) Analysis of crystal structure The crystal structure of the zirconium oxide nanoparticles was analyzed using an X-ray diffractometer (RINT-TTRIII, manufactured by Rigaku Corporation). The measurement conditions are as follows.
X-ray source: CuKα (0.154 nm)
X-ray output setting: 50 kV, 300 mA
Sampling width: 0.0200 °
Scan speed: 10.0000 ° / min
Measurement range: 5-90 °
Measurement temperature: 25 ° C

(2) Crystallite diameter calculation by X-ray diffraction analysis The crystallite diameter of the zirconium oxide nanoparticles is based on the half-value width of the 30 ° peak analyzed and calculated by an X-ray diffractometer (RINT-TTRIII, manufactured by Rigaku Corporation). In addition, calculation was performed using calculation software (Rigaku Corporation, PDXL).

(3) Measurement of weight (mass) reduction rate Using a TG-DTA (thermogravimetric-differential thermal analysis) device, the temperature of zirconium oxide nanoparticles coated at 10 ° C / min from room temperature to 800 ° C was increased in an air atmosphere. The weight (mass) reduction rate of the particles was measured. From this weight (mass) reduction rate, it is possible to know the proportion of carboxylic acid covering zirconium oxide nanoparticles and the proportion of zirconium oxide.

(4) X-ray fluorescence analysis Using a fluorescent X-ray analyzer (manufactured by ZSX Primus II Rigaku), the zirconium content and the second metal content in the coated zirconium oxide nanoparticles were measured.

Example 1
Preparation of lanthanum-containing zirconia nanoparticles coated with 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid 2-ethylhexanoic acid zirconium mineral spirit solution (83 g, zirconium content 12 mass%, first rare 2-ethylhexanoic acid lanthanum (III) (19 g, lanthanum content 7% by mass, manufactured by Wako Pure Chemical Industries, Ltd.) and pure water (16 g) are mixed with a 200 mL hydrothermal synthesis container. Was charged. The vessel was heated to 190 ° C. and kept at that temperature for 8 hours to be reacted. The pressure during hydrothermal synthesis was 1.4 MPaG (gauge pressure). 14 g of white lanthanum-containing zirconium oxide nanoparticles were recovered by taking out the mixed solution after the reaction and removing the solvent.

  When the crystal structure of the lanthanum-containing zirconia nanoparticles was measured according to the above-mentioned “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal crystals and / or cubic crystals were detected, and the above “(2) X-rays” The crystallite diameter measured according to “Calculation of crystallite diameter by diffraction analysis” was 3 nm.

  The mass reduction rate of the coated lanthanum-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 24% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid coating the lanthanum-containing zirconium oxide nanoparticles was 24% by mass of the entire coated lanthanum-containing zirconium oxide nanoparticles. .

  Furthermore, the weight abundance ratio of zirconium and lanthanum in the lanthanum-containing zirconium oxide nanoparticles measured according to “(4) X-ray fluorescence analysis” was 89:10.

Example 2
Preparation of tin-containing zirconia nanoparticles coated with 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid Instead of lanthanum (III) 2-ethylhexanoate in Example 1, 2-ethylhexanoic acid The synthesis was performed in the same manner as in Example 1 except that tin (II) (4.9 g, tin content 29 mass%, manufactured by Wako Pure Chemical Industries, Ltd.) was used. After the reaction, 14 g of white tin-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the tin-containing zirconia nanoparticles was measured according to the above-mentioned “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal crystals and / or cubic crystals and monoclinic crystals were detected. The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 3 nm.

  Moreover, the mass reduction rate of the coated tin-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 25% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid coating the tin-containing zirconium oxide nanoparticles was 25% by mass of the total coated tin-containing zirconium oxide nanoparticles. .

  Furthermore, the weight abundance ratio of zirconium and tin in the tin-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 87:13.

Example 3-1
Preparation of zinc-containing zirconia nanoparticles coated with 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid Instead of lanthanum (III) 2-ethylhexanoate in Example 1, 2-ethylhexanoic acid Synthesis was performed in the same manner as in Example 1 except that zinc (II) (6.6 g, zinc content 15% by mass, manufactured by Wako Pure Chemical Industries, Ltd.) was used. After the reaction, 14 g of white zinc-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the zinc-containing zirconia nanoparticles was measured according to the above-mentioned “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal crystals and / or cubic crystals and monoclinic crystals were detected. The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 4 nm.

  Moreover, the mass reduction rate of the coated zinc-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 26 mass%. Accordingly, it was found that 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid coating the zinc-containing zirconium oxide nanoparticles was 26% by mass of the total coated zinc-containing zirconium oxide nanoparticles. .

  Furthermore, the weight ratio of zirconium to zinc in the zinc-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 90: 9.

Example 3-2
The synthesis was performed in the same manner as in Example 3-1, except that 0.66 g of zinc 2-ethylhexanoate (II) in Example 3-1 was used. After the reaction, 13 g of white zinc-containing zirconium oxide nanoparticles were recovered.

  Furthermore, the weight ratio of zirconium to zinc in the zinc-containing zirconium oxide nanoparticles measured according to “(4) X-ray fluorescence analysis” was 98: 1.

Example 3-3
The synthesis was performed in the same manner as in Example 3-1, except that 1.3 g of zinc 2-ethylhexanoate (II) in Example 3-1 was used. After the reaction, 14 g of white zinc-containing zirconium oxide nanoparticles were recovered.

  Furthermore, the weight ratio of zirconium and zinc in the zinc-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 97: 2.

Example 3-4
The synthesis was performed in the same manner as in Example 3-1, except that 2.6 g of zinc 2-ethylhexanoate (II) in Example 3-1 was used. After the reaction, 14 g of white zinc-containing zirconium oxide nanoparticles were recovered.

  Furthermore, the weight ratio of zirconium and zinc in the zinc-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 95: 4.

Example 4
Preparation of cerium-containing zirconia nanoparticles coated with 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid Instead of lanthanum (III) 2-ethylhexanoate in Example 1, 2-ethylhexanoic acid Synthesis was performed in the same manner as in Example 1 except that cerium (III) ALFA AESAR (14 g, cerium content 12 mass%, registered trademark, manufactured by Johnson Matthey) was used. After the reaction, 15 g of yellow-brown cerium-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the cerium-containing zirconia nanoparticles was measured according to the above-mentioned “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal crystals and / or cubic crystals and monoclinic crystals were detected. The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 4 nm.

  The mass reduction rate of the coated cerium-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 26% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or 2-ethylhexanoic acid-derived carboxylate coating the cerium-containing zirconium oxide nanoparticles was 26% by mass of the total coated cerium-containing zirconium oxide nanoparticles. .

  Furthermore, the weight ratio of zirconium to cerium in the cerium-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 88:12.

Example 5
Preparation of indium-containing zirconia nanoparticles coated with 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid Instead of lanthanum (III) 2-ethylhexanoate in Example 1, 2-ethylhexanoic acid The synthesis was performed in the same manner as in Example 1 except that indium (III) (28 g, indium content 5 mass%, manufactured by Wako Pure Chemical Industries, Ltd.) was used. After the reaction, 14 g of white indium-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the indium-containing zirconia nanoparticles was measured according to the above “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal crystals and / or cubic crystals and monoclinic crystals were detected. The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 5 nm.

  Further, the mass reduction rate of the coated indium-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 27% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid coating the indium-containing zirconium oxide nanoparticles was 27% by mass of the total coated indium-containing zirconium oxide nanoparticles. .

  Furthermore, the weight ratio of zirconium to indium in the indium-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 86:14.

Example 6
Preparation of bismuth-containing zirconia nanoparticles coated with 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid Instead of lanthanum (III) 2-ethylhexanoate of Example 1, 2-ethylhexanoic acid Synthesis was performed in the same manner as in Example 1 except that bismuth (III) (10 g, bismuth content 25% by mass, manufactured by Wako Pure Chemical Industries, Ltd.) was used. After the reaction, 14 g of white bismuth-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the bismuth-containing zirconia nanoparticles was measured according to the above-mentioned “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal crystals and / or cubic crystals and monoclinic crystals were detected. The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 5 nm.

  Moreover, the mass reduction rate of the coated bismuth-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 25% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid coating the bismuth-containing zirconium oxide nanoparticles was 25% by mass of the total coated bismuth-containing zirconium oxide nanoparticles. .

  Furthermore, the weight ratio of zirconium to bismuth in the bismuth-containing zirconium oxide nanoparticles measured according to “(4) X-ray fluorescence analysis” was 80:20.

Example 7
Preparation of iron-containing zirconia nanoparticles coated with carboxylate derived from 2-ethylhexanoic acid and / or 2-ethylhexanoic acid Instead of lanthanum (III) 2-ethylhexanoate in Example 1, 2-ethylhexanoic acid The synthesis was performed in the same manner as in Example 1 except that iron (III) (3.0 g, iron content 6 mass%, manufactured by Wako Pure Chemical Industries, Ltd.) was used. After the reaction, 14 g of reddish brown iron-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the iron-containing zirconia nanoparticles was measured according to “(1) Analysis of crystal structure” described above, diffraction lines belonging to tetragonal crystals and / or cubic crystals and monoclinic crystals were detected. The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 5 nm.

  Moreover, the mass reduction rate of the coated iron-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 23% by mass. Accordingly, it was found that 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid coating the iron-containing zirconium oxide nanoparticles was 23% by mass of the total coated iron-containing zirconium oxide nanoparticles. .

  Furthermore, the weight ratio of zirconium to iron in the iron-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 96: 3.

Example 8-1
Preparation of cobalt-containing zirconia nanoparticles coated with carboxylate derived from 2-ethylhexanoic acid and / or 2-ethylhexanoic acid Instead of lanthanum (III) 2-ethylhexanoate in Example 1, 2-ethylhexanoic acid The synthesis was performed in the same manner as in Example 1 except that cobalt (II) (1.8 g, cobalt content 11 mass%, manufactured by Sigma-Aldrich) was used. After the reaction, 14 g of purple cobalt-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the cobalt-containing zirconia nanoparticles was measured according to the above-mentioned “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal crystals and / or cubic crystals and monoclinic crystals were detected. The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 4 nm.

  Moreover, the mass reduction rate of the coated cobalt-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 25% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or 2-ethylhexanoic acid-derived carboxylate coating the cobalt-containing zirconium oxide nanoparticles was 25% by mass of the total coated cobalt-containing zirconium oxide nanoparticles. .

  Furthermore, the weight ratio of zirconium to cobalt in the cobalt-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 96: 3.

Example 8-2
Preparation of cobalt-containing zirconia nanoparticles coated with carboxylate derived from 2-ethylhexanoic acid and / or 2-ethylhexanoic acid Instead of lanthanum (III) 2-ethylhexanoate in Example 1, 2-ethylhexanoic acid The synthesis was performed in the same manner as in Example 1 except that cobalt (II) (6.4 g, cobalt content 11 mass%, manufactured by Sigma-Aldrich) was used. After the reaction, 15 g of purple cobalt-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the cobalt-containing zirconia nanoparticles was measured according to the above-mentioned “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal crystals and / or cubic crystals and monoclinic crystals were detected. The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 4 nm.

  Moreover, the mass reduction rate of the coated cobalt-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 25% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or 2-ethylhexanoic acid-derived carboxylate coating the cobalt-containing zirconium oxide nanoparticles was 25% by mass of the total coated cobalt-containing zirconium oxide nanoparticles. .

  Furthermore, the weight ratio of zirconium to cobalt in the cobalt-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 89:10.

Example 9
Preparation of manganese-containing zirconia nanoparticles coated with 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid Instead of lanthanum (III) 2-ethylhexanoate in Example 1, 2-ethylhexanoic acid Synthesis was performed in the same manner as in Example 1 except that manganese (II) (2.4 g, manganese content 8 mass%, manufactured by Wako Pure Chemical Industries, Ltd.) was used. After the reaction, 14 g of purple manganese-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the manganese-containing zirconia nanoparticles was measured according to the above-mentioned “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal crystals and / or cubic crystals and monoclinic crystals were detected. The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 4 nm.

  The mass reduction rate of the coated manganese-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 25% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid coating the manganese-containing zirconium oxide nanoparticles was 25% by mass of the total coated manganese-containing zirconium oxide nanoparticles. .

  Further, the weight ratio of zirconium and manganese in the manganese-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 96: 3.

Example 10
Preparation of nickel-containing zirconia nanoparticles coated with carboxylate derived from 2-ethylhexanoic acid and / or 2-ethylhexanoic acid Instead of lanthanum (III) 2-ethylhexanoate in Example 1, 2-ethylhexanoic acid The synthesis was performed in the same manner as in Example 1 except that nickel (II) (2.0 g, nickel content 10 mass%, manufactured by Nippon Chemical Industry Co., Ltd.) was used. After the reaction, 14 g of light red nickel-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the nickel-containing zirconia nanoparticles was measured according to the above-mentioned “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal crystals and / or cubic crystals and monoclinic crystals were detected. The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 4 nm.

  Further, the mass reduction rate of the coated nickel-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 25% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid coating the nickel-containing zirconium oxide nanoparticles was 25% by mass of the total coated nickel-containing zirconium oxide nanoparticles. .

  Furthermore, the weight ratio of zirconium to nickel in the nickel-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 96: 3.

Example 11-1
Production of copper-containing zirconia nanoparticles coated with 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid and neodecanoic acid and / or carboxylate derived from neodecanoic acid 2-ethylhexanoic acid of Example 1 The synthesis was performed in the same manner as in Example 1 except that copper (II) neodecanoate (4.5 g, copper content 5 mass%, manufactured by Nippon Chemical Industry Co., Ltd.) was used instead of lanthanum (III). After the reaction, 14 g of dark green copper-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the copper-containing zirconia nanoparticles was measured according to the above-mentioned “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal crystals and / or cubic crystals and monoclinic crystals were detected. The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 4 nm.

  Further, the mass reduction rate of the coated copper-containing zirconium oxide nanoparticles measured according to “(3) Measurement of weight (mass) reduction rate” was 27% by mass. Therefore, 2-ethylhexanoic acid and / or 2-ethylhexanoic acid-derived carboxylate that coats copper-containing zirconium oxide nanoparticles and neodecanoic acid and / or neodecanoic acid-derived carboxylate are coated with copper-containing zirconium oxide. It was found to be 27% by mass of the total nanoparticles.

  Furthermore, the weight ratio of zirconium and copper in the copper-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 96: 3.

Example 11-2
Production of copper-containing zirconia nanoparticles coated with 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid and neodecanoic acid and / or carboxylate derived from neodecanoic acid 2-ethylhexanoic acid of Example 1 Synthesis was performed in the same manner as in Example 1 except that copper (II) neodecanoate (15 g, copper content 5 mass%, manufactured by Nippon Chemical Industry Co., Ltd.) was used instead of lanthanum (III). After the reaction, 16 g of dark green copper-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the copper-containing zirconia nanoparticles was measured according to the above-mentioned “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal crystals and / or cubic crystals and monoclinic crystals were detected. The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 4 nm.

  Moreover, the mass reduction rate of the coated copper-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 28% by mass. Therefore, 2-ethylhexanoic acid and / or 2-ethylhexanoic acid-derived carboxylate that coats copper-containing zirconium oxide nanoparticles and neodecanoic acid and / or neodecanoic acid-derived carboxylate are coated with copper-containing zirconium oxide. It was found to be 28% by mass of the total nanoparticles.

  Furthermore, the weight ratio of zirconium to copper in the copper-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 90: 9.

Example 12-1
Preparation of europium-containing zirconia nanoparticles coated with 2-ethylhexanoic acid and / or 2-ethylhexanoic acid-derived carboxylate In place of lanthanum (III) 2-ethylhexanoate in Example 1, 2-ethylhexanoic acid The synthesis was performed in the same manner as in Example 1 except that europium (III) (1.42 g, europium content 26 mass%, manufactured by Strem Chemical Co.) was used. After the reaction, 16 g of pale pink europium-containing zirconium oxide nanoparticles were recovered.

  When the crystal structure of the europium-containing zirconia nanoparticles was measured according to the above-mentioned “(1) Analysis of crystal structure”, diffraction lines belonging to tetragonal and / or cubic and monoclinic crystals were detected, and “(( The crystallite diameter measured according to “2) Calculation of crystallite diameter by X-ray diffraction analysis” was 4 nm.

  Further, the mass reduction rate of the coated europium-containing zirconium oxide nanoparticles measured according to the above “(3) Measurement of weight (mass) reduction rate” was 26% by mass. Therefore, it was found that 2-ethylhexanoic acid and / or carboxylate derived from 2-ethylhexanoic acid coating the europium-containing zirconium oxide nanoparticles was 26% by mass of the total coated europium-containing zirconium oxide nanoparticles. .

  Furthermore, the weight ratio of zirconium and europium in the europium-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 97: 3.

Example 12-2
Production of europium-containing zirconia nanoparticles coated with 2-ethylhexanoic acid and / or 2-ethylhexanoic acid-derived carboxylate Europium chloride hexahydrate (7.32 g, manufactured by Wako Pure Chemical Industries, Ltd.), 2-ethyl Sodium hexanoate (9.96 g, manufactured by Tokyo Chemical Industry Co., Ltd.) and ion-exchanged water (100 mL) and toluene (100 mL, manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a three-necked flask and purged with nitrogen. Then, it heated for 3 hours under reflux conditions, performing nitrogen bubbling. The obtained solution was transferred to a separatory funnel, the aqueous phase was removed, and the organic phase was washed three times with pure water to obtain 80 g of europium toluene solution of 2-ethylhexanoate (europium content 3.5%). It was.
To a 2-ethylhexanoic acid zirconium mineral spirit solution (60 g, zirconium content 12% by mass, manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.), 20 g of 2-ethylhexanoic acid europium toluene solution synthesized by the above method and pure water (13 g) ) And charged into a 200 mL hydrothermal synthesis vessel. The vessel was heated to 190 ° C. and kept at that temperature for 8 hours to be reacted. The pressure during hydrothermal synthesis was 1.4 MPaG (gauge pressure). 14 g of pale pink europium-containing zirconium oxide nanoparticles were recovered by removing the mixed liquid after the reaction and removing the solvent.

  Further, the mass reduction rate of the coated europium-containing zirconium oxide nanoparticles measured according to “(3) Measurement of weight (mass) reduction rate” was 28% by mass. Therefore, it was found that the 2-ethylhexanoic acid and / or 2-ethylhexanoic acid-derived carboxylate coating the europium-containing zirconium oxide nanoparticles was 28% by mass of the total coated europium-containing zirconium oxide nanoparticles. .

  Furthermore, the weight ratio of zirconium and europium in the europium-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 91: 9.

Example 12-3
Production of europium-containing zirconia nanoparticles coated with 2-ethylhexanoic acid and / or 2-ethylhexanoic acid-derived carboxylate Europium chloride hexahydrate (7.32 g, manufactured by Wako Pure Chemical Industries, Ltd.), 2-ethyl Sodium hexanoate (9.96 g, manufactured by Tokyo Chemical Industry Co., Ltd.) and ion-exchanged water (100 mL) and toluene (100 mL, manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a three-necked flask and purged with nitrogen. Then, it heated for 3 hours under reflux conditions, performing nitrogen bubbling. The obtained solution was transferred to a separatory funnel, the aqueous phase was removed, and the organic phase was washed three times with pure water to obtain 80 g of europium toluene solution of 2-ethylhexanoate (europium content 3.5%). It was.
Zirconium 2-ethylhexanoate mineral spirit solution (50 g, zirconium content 12% by mass, manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.) 40 g of europium 2-ethylhexanoate toluene solution synthesized by the above method and pure water (13 g) ) And charged into a 200 mL hydrothermal synthesis vessel. The vessel was heated to 190 ° C. and kept at that temperature for 8 hours to be reacted. The pressure during hydrothermal synthesis was 1.4 MPaG (gauge pressure). 14 g of pale pink europium-containing zirconium oxide nanoparticles were recovered by removing the mixed liquid after the reaction and removing the solvent.

  Further, the mass reduction rate of the coated europium-containing zirconium oxide nanoparticles measured according to “(3) Measurement of weight (mass) reduction rate” was 28% by mass. Therefore, it was found that the 2-ethylhexanoic acid and / or 2-ethylhexanoic acid-derived carboxylate coating the europium-containing zirconium oxide nanoparticles was 28% by mass of the total coated europium-containing zirconium oxide nanoparticles. .

  Furthermore, the weight ratio of zirconium and europium in the europium-containing zirconium oxide nanoparticles measured according to the above “(4) X-ray fluorescence analysis” was 71:29.

  1 to 8 show X-ray diffraction charts obtained by analyzing zirconia nanoparticles containing each second metal element according to the above “(1) Analysis of crystal structure”. Also, for the lanthanum-containing zirconia nanoparticles of Example 1, the cerium-containing zirconia nanoparticles of Example 4, the indium-containing zirconia nanoparticles of Example 5, and the europium-containing zirconia nanoparticles of Examples 12-1 to 12-3, The crystal structure of the ceramic material obtained by firing these particles at 1000 ° C. for 2 hours was also analyzed. 8A, 8B, and 8C show the results of Examples 12-1, 12-2, and 12-3, respectively.

  For any second metal element, it was found that zirconium was stabilized by the second metal element in the form of nanoparticles and existed as a composite oxide.

  When the second metal element is not used, tetragonal crystals and / or cubic crystals are mainly observed in the state of nanoparticles that are not fired, whereas monoclinic crystals are mainly observed in the particles after firing. On the other hand, when at least one of lanthanum, cerium, indium and europium is used as the second metal element, tetragonal crystals and / or cubic crystals are mainly observed in the non-fired nanoparticle state, and the fired particles are single. Oblique crystals were not observed, and it was confirmed that tetragonal crystals or cubic crystals were observed. From this, lanthanum, cerium, indium, and europium may have an effect of stabilizing the crystal phase of zirconia particles.

  In addition, two peaks are observed in the vicinity of 2θ = 30, 35, 60, and 75 ° after firing in FIG. 8A, whereas 2θ = 30, 35, 60, and 75 after firing in FIG. 8C. Only one mountain was observed at the peak near 75 °. This is because the zirconia nanoparticles containing 3% europium shown in FIG. 8A have a tetragonal crystal structure after firing, whereas the zirconia nanoparticles containing 29% europium shown in FIG. This means that the crystal structure is cubic.

Claims (10)

Zirconium oxide nanoparticles coated with a first carboxylic acid having 3 or more carbon atoms,
It contains at least one metal element selected from the group consisting of La, Ce, Eu, Fe, Co, Sn, Zn, In, Bi, Mn, Ni and Cu (however, it does not contain yttrium) Zirconium oxide nanoparticles.   The zirconium oxide nanoparticles according to claim 1, wherein the first carboxylic acid is at least one of a primary carboxylic acid and a secondary carboxylic acid.   The first carboxylic acid is at least one selected from the group consisting of secondary carboxylic acids, carboxylic acids having branched carbon atoms other than the α-position, and linear carboxylic acids having 4 to 20 carbon atoms. Item 3. The zirconium oxide nanoparticles according to Item 1 or 2.   The total content of at least one metal element selected from the group consisting of La, Ce, Eu, Fe, Co, Sn, Zn, In, Bi, Mn, Ni and Cu is the total content of these metal elements and zirconium. The zirconium oxide nanoparticles according to claim 3, which is 0.1 to 40% by mass with respect to the amount.   The dispersion liquid containing the zirconium oxide nanoparticle in any one of Claims 1-4.   The resin composition containing the zirconium oxide nanoparticle in any one of Claims 1-4.   The molding material containing the zirconium oxide nanoparticle in any one of Claims 1-4.   A ceramic material obtained from the zirconium oxide nanoparticles according to claim 1.   A method for producing a ceramic material, comprising firing the zirconium oxide nanoparticles according to any one of claims 1 to 4 at 500 ° C or higher.   A method for producing a ceramic material, comprising calcining a composition containing zirconium oxide nanoparticles according to any one of claims 1 to 4 at 500 ° C or higher.

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