JP6742761B2 - Zirconium oxide nanoparticles - Google Patents

Description

The present invention relates to zirconium oxide nanoparticles.

In recent years, metal oxide nanoparticles have the possibility of exhibiting various functions in optical materials, electronic component materials, etc., and have attracted attention in the field of various functional materials. However, since the metal oxide alone has insufficient dispersibility in an organic medium, it often aggregates, 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, in Patent Document 1, two or more kinds of coating agents are coated, and at least one of the coating agents is represented by the formula of R ¹ —COOH (R ¹ is a hydrocarbon group having 6 or more carbon atoms). Zirconium oxide nanoparticles are disclosed, and it is described that such zirconium oxide nanoparticles can improve dispersibility in a nonpolar solvent or the like. As a coating agent represented by the above formula, neodecanoic acid is disclosed in Examples of Patent Document 1.

In recent years, a technique for stabilizing metal oxide particles with a rare earth oxide has been proposed. The neodecanoic acid disclosed in Patent Document 1 is classified into a tertiary carboxylic acid, but in Non-Patent Document 1, it is stabilized with a rare earth oxide using a metal complex of a tertiary carboxylic acid as a starting material. Zirconia fine particles are disclosed. In Non-Patent Document 1, zirconia particles are produced by hydrothermally synthesizing a solution of Zr(IV)-carboxylate and Y(III)-carboxylate at a predetermined ratio as a starting material together with an aqueous MgSO ₄ solution. Is disclosed.

JP, 2008-44835, A

"Rare Earth Oxide-Stabilized Zirconia Fine Particles Starting from Metal Carboxylate", Chemical Engineering Society of Japan, Autumn Meeting of the Japan Society for Chemical Engineering, 2001, 34, 16

INDUSTRIAL APPLICABILITY The present invention is easily stabilized with a rare earth oxide or the like without using the sulfate aqueous solution such as the MgSO ₄ aqueous solution disclosed in Non-Patent Document 1 described above, or the amount thereof is reduced, and the organic medium is The object is to obtain zirconium oxide particles exhibiting excellent dispersibility.

The present invention that has achieved the above object is a zirconium oxide nanoparticle coated with a first carboxylic acid that is at least one of a primary carboxylic acid and a secondary carboxylic acid and has a carbon number of 3 or more, The zirconium oxide nanoparticles are zirconium oxide nanoparticles characterized by containing yttrium. The zirconium oxide nanoparticles of the present invention preferably further contain at least one of Al and a rare earth element (other than yttrium). The first carboxylic acid is at least one selected from the group consisting of a secondary carboxylic acid, a carboxylic acid having a branched carbon atom other than the α-position, and a linear carboxylic acid having 4 to 20 carbon atoms. Is preferred. The total content of Al and rare earth elements is preferably 0.1% by mass or more in terms of ratio to zirconium.

The zirconium oxide nanoparticles of the present invention are preferably coated with at least one kind of organic acid other than the first carboxylic acid, a silane coupling agent, a surfactant and an organic phosphorus compound.

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

The present invention also includes a ceramic material obtained from any of the zirconium oxide nanoparticles and a method for producing the ceramic material. In the manufacturing method, any one of the above zirconium oxide nanoparticles is fired at 500° C. or higher, or a composition containing any of the above zirconium oxide nanoparticles is fired at 500° C. or higher. It is a method of manufacturing a material.

Furthermore, in the present invention, the first carboxylic acid is at least selected from the group consisting of a secondary carboxylic acid, a carboxylic acid having a branched carbon atom other than the α-position, and a linear carboxylic acid having 4 to 20 carbon atoms. A method for producing one type of zirconium oxide nanoparticles is also included, which comprises a secondary carboxylic acid, a carboxylic acid having a branched carbon atom other than the α-position, and a linear carboxylic acid having 4 to 20 carbon atoms. A zirconium raw material composed of at least one first carboxylic acid selected from the group consisting of zirconium or a zirconium-containing compound, the first carboxylic acid, Al, a rare earth element, an Al-containing compound, and A method for producing zirconium oxide nanoparticles, comprising hydrothermally synthesizing Al or a rare earth element raw material composed of at least one kind of rare earth element-containing compound without using MgSO ₄ .

According to the present invention, since a specific carboxylic acid is used, it is coated with a carboxylic acid and contains yttrium, and optionally, a rare earth element other than Al or yttrium (hereinafter, referred to as “rare earth element or the like”). The zirconium oxide nanoparticles containing a can be easily obtained without using MgSO ₄ or the like or by reducing the amount used. Such zirconium oxide nanoparticles have good dispersibility in an organic medium due to the use of a specific carboxylic acid, and have a stable crystal structure by containing a rare earth element and the like. When the particles are fired, the change in crystal structure can be suppressed.

Since the zirconium oxide nanoparticles of the present invention are coated with the specific first carboxylic acid, the zirconium oxide nanoparticles have good dispersibility in an organic medium such as a solvent or a resin, and at the same time, yttrium is essential and, if necessary, a rare earth element. Therefore, the crystal structure of zirconium oxide is stable, that is, the change in the crystal structure before and after firing is suppressed. Further, since the specific first carboxylic acid is used, MgSO ₄ which is required when a metal complex of a tertiary carboxylic acid as in Non-Patent Document 1 described above is used as a starting material and fulfills a catalytic function. Zirconium oxide nanoparticles can be obtained by hydrothermal synthesis without using an aqueous solution.

The first carboxylic acid in the present invention is at least one of primary carboxylic acid and secondary carboxylic acid, and has 3 or more carbon atoms. The primary carboxylic acid means a carboxylic acid having a carboxyl group bonded to a primary alkyl group, and the secondary carboxylic acid means a carboxylic acid having a carboxyl group bonded to a secondary alkyl group. .. Therefore, the first carboxylic acid of the present invention is a primary carboxylic acid and a secondary carboxylic acid excluding formic acid and acetic acid. The first carboxylic acid is preferably a secondary carboxylic acid, a carboxylic acid having a branched carbon atom other than the α-position, or a linear carboxylic acid having 4 to 20 carbon atoms, and is coated with at least one of these. Preferably. Among these, the secondary carboxylic acid and at least one of the carboxylic acids having a carbon atom other than the α-position branched are more preferable, and the secondary carboxylic acid is further preferable.

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, and 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-propylbutyric acid, 2-hexyldecanoic acid, 2-heptylundecane Acid, 2-methylhexadecanoic acid, 4-methylcyclohexacarboxylic acid and the like can be mentioned.

A 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. The carbon number of such carboxylic acid is preferably 4 to 20, more preferably 5 to 18, and examples thereof include isovaleric acid, 3,3-dimethylbutyric acid, 3-methylvaleric acid, isononanoic acid, and 4-methylvaleric acid. , 4-methyl-n-octanoic acid and the like.

The linear carboxylic acid (preferably the linear saturated aliphatic carboxylic acid) has 4 to 20 carbon atoms, preferably 5 or more, and more preferably 8 or more. Examples of the linear carboxylic acid having 4 to 20 carbon atoms include butyric acid, valeric acid, hexanoic acid, heptanoic acid, caprylic acid, nonanoic acid, decanoic acid, lauric acid, tetradecanoic acid, stearic acid, and the like. Caprylic acid, lauric acid and stearic acid.

The amount of the first carboxylic acid is, for example, 5 to 25 mass% (preferably 10 mass% or more, more preferably 13 mass% or more) with respect to 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 below, the total amount of the first carboxylic acid and the organic acid other than the first carboxylic acid is as described above. It should be within the range of.

In addition, that the zirconium oxide nanoparticles of the present invention are coated with the first carboxylic acid means that the state in which the first carboxylic acid is chemically bonded to the zirconium oxide nanoparticles and the state in which the first carboxylic acid is physically bonded to the zirconium oxide nanoparticles are both. It is also meant to include, and is meant to be coated with the first carboxylic acid and/or the carboxylate derived from the first carboxylic acid.

The zirconium oxide nanoparticles of the present invention essentially contain yttrium and, if necessary, further contain at least one kind of rare earth element other than Al and yttrium, and the crystal structure of the zirconium oxide crystal is stable. That is, it is possible to increase the proportion of tetragonal crystals and/or cubic crystals in the zirconium oxide nanoparticles of the present invention, and it is possible to suppress the reduction of tetragonal crystals when the zirconium oxide nanoparticles are calcined, so that the proportion of tetragonal crystals after calcining can be reduced. Can be higher The rare earth elements include Sc, Y (yttrium), and lanthanoid series elements having atomic numbers 57 (La) to 71 (Lu).

In the present invention, yttrium is an essential component, and among Al and rare earth elements, preferably one or more of Al, La, Yb, Sc, Ce and Er may be further contained, more preferably one or more of Al, Sc and Er. May be included.

The contents of Al and rare earth elements (including yttrium) (the content of yttrium in the case of only yttrium, the total content in the case of containing one or more other yttrium) are zirconium of zirconium oxide, Al and rare earths. The ratio to the total amount of elements is, for example, 0.1 to 20% by mass, preferably 0.5% by mass or more, more preferably 1% by mass or more, further preferably 3% by mass or more, particularly preferably 4% by mass or more. , And most preferably 5% by mass or more. In particular, when the content is 3% by mass or more, the proportion of tetragonal crystals after firing can be increased as compared with that before firing.

The ratio of zirconium contained in the zirconium oxide nanoparticles of the present invention is, for example, 80% by mass or more based on the total of all metal elements contained in the zirconium nanoparticles. Further, as the metal element contained in the zirconium oxide nanoparticles of the present invention, a metal element other than zirconium, Al and a rare earth element may be contained. Metal elements other than zirconium, Al and rare earth elements are usually metal elements of Group 3 or later of the periodic table, and the total content thereof is not particularly limited, but is, for example, 3% by mass or less, preferably 2% by mass or less, It is more preferably 1% by mass or less, and may be 0% by mass.

The zirconium oxide particles of the present invention are organic acids other than the first carboxylic acid obtained by subjecting the zirconium oxide particles coated with the first carboxylic acid obtained after the hydrothermal synthesis reaction to room temperature or heating for surface treatment. The surface may be modified with a silane coupling agent, a surfactant, an organic phosphorus compound, or the like. By subjecting the nanoparticles obtained first to surface treatment again, it becomes possible to control the miscibility with other substances as a firing precursor, the moldability, etc., so that it can be applied to various applications. become. The preferable organic acid, silane coupling agent, surfactant and organic phosphorus compound will be 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 chemically bonds to the zirconium oxide nanoparticles or forms a carboxylic acid or a salt thereof with a hydrogen atom or a cationic atom and attaches to the zirconium oxide nanoparticles, the term "coating" in the present invention means a carboxylic acid. It includes both a state in which the acid compound is chemically bonded to zirconium oxide and a 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 a solvent and the properties of materials other than zirconium oxide nanoparticles, but (meth)acrylic acid, ester Group, ether group, hydroxyl group, amino group, amide group, thioester group, thioether group, carbonate group, urethane group, and carboxylic acid having one or more substituents selected from the group consisting of urea groups, having 4 to 20 carbon atoms. Hydrocarbons having one or more (preferably one) carboxylic acid group such as a linear carboxylic acid, a branched carboxylic acid, a cyclic carboxylic acid, or an aromatic carboxylic acid are preferably adopted.

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

The addition amount of the carboxylic acid compound is preferably 0.1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the zirconium oxide nanoparticles.

<Silane coupling agent>
As the silane coupling agent, a compound having a hydrolyzable group —Si—OR ⁹ (wherein R ⁹ is a methyl group or an ethyl group) is preferable. Examples of such a silane coupling agent include a silane coupling agent having a functional group and alkoxysilane.

The silane coupling agent having a functional group is represented by the following formula (1):
_{[X- (CH 2) m]} 4-n -Si- (OR 9) n ... (1)
(In the formula, X is a functional group, R ⁹ 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 group as a functional group X such as vinyltrimethoxysilane and vinyltriethoxysilane; 3-aminopropyltrimethoxysilane, 3-aminopropyltrisilane. Silane coupling in which the functional group X of ethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyltrimethoxysilane, etc. is an amino group. Agents: 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, etc. A silane coupling agent in which the group X is a (meth)acryloxy group; a silane coupling agent in which the functional group X is a mercapto group such as 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane; 2-(3, 4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane And the like, a silane coupling agent having a functional group X such as glycidoxy group.

Examples of the alkoxysilane include methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, propyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, and decyltrimethoxysilane. Alkyl group-containing alkoxysilane in which alkyl group such as silane is directly bonded to silicon atom of alkoxysilane; aromatic ring such as phenyltrimethoxysilane, diphenyldimethoxysilane, p-styryltrimethoxysilane is directly bonded to silicon atom of alkoxysilane And the like, a bonded aryl group-containing alkoxysilane;

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

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

<Surfactant>
The surfactant can improve the transparency and dispersibility of the composition. Further, it is possible to achieve low viscosity of the composition. As the surfactant, an ionic surfactant such as an anionic surfactant, a cationic surfactant, a zwitterionic surfactant, or a nonionic surfactant is preferably used, and an anionic 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 sodium sulfonate, phosphate such as sodium alkyl phosphate ester, and alpha olein sulfone. Olefins such as sodium acid salt, alcohols such as sodium alkylsulfate, alkylbenzenes, and the like, examples of the cationic surfactant include alkylmethylammonium chloride, alkyldimethylammonium chloride, alkyltrimethylammonium chloride, and alkyldimethylbenzyl chloride. Ammonium or the like is used as the zwitterionic surfactant, for example, a carboxylic acid-based surfactant such as an alkylaminocarboxylic acid salt, or a phosphate ester-based surfactant such as phosphobetaine, and a nonionic surfactant is, for example, polyoxyethylene. Examples thereof include fatty acid compounds such as lauric fatty acid ester and polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkyl phenyl ether, and fatty acid alkanolamide. The surfactant is preferably added in an amount of 0.1% by mass or more and 5% by mass or less based on 100% by mass of all components of the composition.

<Organophosphorus compound>
As the organic phosphorus compound, for example, the following formula:

(In the above formula, each of p ¹ and p ² is preferably from 1 to 100, more preferably from 1 to 50, further preferably from 1 to 30, and more preferably from 4 to 15. p ¹ +p ² is preferably 1 to 100, more preferably 1 to 50, and further preferably 1 to 30.), and phosphoric acid diesters having the same substituents as these. To be

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, further preferably 1 to 30, and 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. And 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, * is a phosphorus atom A compound such as a phosphoric acid monoester or a phosphoric acid diester represented by 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, p ¹ is preferably ¹ to 100, more preferably 1 to 50, and further preferably 1 to 30.) A compound represented by the formula (for example, formula:

(In the above formula, p ¹ is preferably ¹ to 100, more preferably 1 to 50, and further preferably 1 to 30)) or the following formula:

Examples include various phosphoric acid compounds or phosphoric acid esters represented by:

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

Examples of the above-mentioned organic phosphorus compound 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 Chemistry Co., Ltd.), and 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 (Big Chemie Japan Co., Ltd.), KAYAMER PM-2. , A commercially available phosphoric acid ester such as KAYAMER PM-21 (manufactured by Nippon Kayaku Co., Ltd.) can be appropriately used.

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 crystal structure of the zirconium oxide nanoparticles of the present invention is cubic, tetragonal, or monoclinic, and the total of tetragonal and cubic is preferably 80% or more of the total crystal structure. The total proportion of tetragonal crystals and cubic crystals is preferably 85% or more, more preferably 90% or more. It may be tetragonal alone or cubic alone. Further, since the zirconium oxide nanoparticles of the present invention contain Al or a rare earth element, the tetragonal crystal and/or cubic crystal are stable, and the tetragonal crystal and/or cubic crystal of the ceramic material obtained by firing are stable. The percentage is also high. The proportion of tetragonal and/or cubic crystals in the ceramic material obtained by firing the zirconium oxide nanoparticles of the present invention is, for example, 25% or more, preferably 50% or more, and more preferably total of tetragonal crystals and cubic crystals. Is 90% or more. Further, the reduction of tetragonal crystals and/or cubic crystals after firing is suppressed. The amount of change in the total proportion of tetragonal crystals and cubic crystals before and after firing is preferably 70% or less, more preferably 30% or less, still more preferably 10% or less with respect to the total proportion of tetragonal crystals and cubic crystals before firing. Yes, and most preferably 5% or less.

Examples of the shape of the zirconium oxide nanoparticles include spherical shape, granular shape, elliptic spherical shape, cubic shape, rectangular parallelepiped shape, pyramid shape, needle shape, columnar shape, rod shape, tubular shape, flaky shape, plate shape, and flaky shape. Considering the dispersibility in a solvent or the like, the shape is preferably spherical, granular, columnar or the like.

The crystallite diameter of the zirconium oxide nanoparticles calculated by X-ray diffraction analysis is preferably 30 nm or less, and more preferably 20 nm or less. By doing so, the transparency of the composition containing zirconium oxide nanoparticles can be improved. The crystallite size is more preferably 20 nm or less, further preferably 15 nm or less, and particularly preferably 10 nm or less. The lower limit of the crystallite size is usually about 1 nm.

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

The average particle size is randomly obtained by expanding 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), or the like. It can be determined by selecting 100 particles, measuring the length in the major axis direction, and obtaining the arithmetic mean thereof.

The zirconium oxide nanoparticles of the present invention include a zirconium component, Al or a rare earth element component (meaning containing yttrium as an essential element and a rare earth element other than yttrium used as necessary) and a first carboxylic acid. By hydrothermal reaction, zirconium oxide nanoparticles coated with the first carboxylic acid, containing yttrium, and optionally Al or a rare earth element other than yttrium can be obtained. As the zirconium component, a zirconium raw material composed of a first carboxylic acid and zirconium or a zirconium-containing compound (preferably a combined body) can be used. As the Al or rare earth element component, Al or a rare earth element composed (preferably a bond) of the first carboxylic acid and at least one of Al, a rare earth element, an Al-containing compound and a rare earth element-containing compound Raw materials can be used. Since the specific first carboxylic acid is used in the present invention, zirconium oxide nanoparticles can be obtained by hydrothermal synthesis without using MgSO ₄ as used in Non-Patent Document 1 described above. it can.

Specific examples of the zirconium source 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 oxide. At least one selected from zirconium precursors can be used.

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

Hereinafter, as the zirconium oxide precursor, it is preferable to use a water-soluble and highly corrosive zirconium oxide precursor such as a chloride such as zirconium oxychloride or a nitrate such as oxynitrate as the raw material ( The case i) will be described in detail. Incidentally, the salt is not only a single compound composed of a stoichiometric ratio of carboxylic acid and zirconium oxide precursor, but also a complex salt, a composition in which unreacted carboxylic acid or zirconium oxide precursor is present. It may be.

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

The degree of neutralization is preferably 0.1 to 0.8, more preferably 0.2 to 0.7. If it is less than 0.1, the above-mentioned salt may not be sufficiently formed due to the low solubility of the first carboxylic acid compound, and if it exceeds 0.8, a large amount of white precipitate, which is presumed to be a hydroxide of zirconium, is formed. In some cases, the yield of the coated zirconium oxide particles generated may decrease. 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 metal, particularly sodium and potassium are It is suitable.

The ratio of the carboxylate-containing composition to the zirconium oxide precursor is preferably 1 mol to 20 mol of a carboxyl group and more preferably 1.2 to 18 mol 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 the aqueous solutions or the aqueous solution and the organic solvent. The reaction temperature is not particularly limited as long as it can hold the aqueous solution, but is preferably room temperature to 100°C, more preferably 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 or liquid separation. Is preferred.

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

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

The zirconium oxide precursor that can be used in (iii) above is the same as the zirconium oxide precursor described above. In the case of (iii), the zirconium oxide precursor is preferably zirconium carbonate. The ratio of the carboxylic acid and 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. It is more preferably 1.2 mol to 5 mol. The carboxylic acid and the zirconium oxide precursor may be subjected to the hydrothermal reaction as they are, or may be reacted in advance before the hydrothermal reaction. In order to react before the hydrothermal reaction, it is preferable to react the carboxylic acid and the zirconium oxide precursor in a rally in an organic solvent. At that time, it is preferable to remove the water generated during the reaction so as to improve the reaction rate and yield. Since the reaction is carried out while extracting water during the reaction, a solvent having a boiling point higher than that of water is preferably used as the reaction solvent, more preferably the solvent used in the hydrothermal reaction described later. Further, the reaction temperature is preferably 70° C. or higher, more preferably 80° C. or higher so that water can be extracted. The upper limit of the reaction temperature is 180°C or lower, more preferably 150°C or lower. If the temperature is too high, side reactions may proceed and decomposition of carboxylic acid may occur. When water cannot be taken out well during the reaction, the reaction pressure can be lowered to lower the boiling point of water for the reaction.

As the Al or rare earth element raw material, specifically, (i) a salt of a first carboxylic acid and a precursor of an oxide rare earth element, (ii) a salt of a first carboxylic acid of a rare earth element, and ( iii) At least one selected from the first carboxylic acids and precursors of rare earth oxides and the like. Preferred embodiments of (i) to (iii) are the same as the preferred embodiments of (i) to (iii) in the zirconium raw material.

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 Al or rare earth element component are mixed, preferably in the presence of water. At this time, by performing heating or under reduced pressure, low boiling point compounds contained in the zirconium oxide precursor such as ammonia and acetic acid can be expelled to the outside of the system, and pressure increase in the hydrothermal reaction in the next step can be suppressed. Therefore, it is preferable. In addition, you may perform the said reaction in the solution which added the organic solvent mentioned later.

Subsequently, the hydrothermal reaction will be described.
Zirconium oxide nanoparticle composition by subjecting 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 Al or rare earth element component to a hydrothermal reaction The thing is obtained. When the viscosity is high and the hydrothermal reaction does not proceed efficiently only with the above (i) to (iii), it is advisable to add an organic solvent having good solubility in the above (i) to (iii). .. In order to obtain the zirconium oxide nanoparticles of the present invention, it is particularly preferable to use a zirconium component of the first carboxylic acid, a zirconium salt of the first carboxylic acid, or a salt of the rare earth element of the first carboxylic acid as the zirconium component. ..

As the organic solvent, hydrocarbon, ketone, ether, alcohol or the like can be used. An organic solvent having a boiling point of 120° C. or higher under normal pressure is preferable, a temperature of 140° C. or higher is more preferable, and a temperature of 150° C. or higher is further preferable, because the reaction may not proceed sufficiently with a solvent that vaporizes during the hydrothermal reaction. 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 thereof include diol, 2,3-butanediol, hexanediol, glycerin, methanetrimethylol, toluene, xylene, trimethylbenzene, dimethylformamide (DMF) and dimethylsulfoxide (DMSO), and dodecane, tetradecane and trimethylbenzene are preferable.

When the organic solvent is added to separate into two layers, a surfactant or the like may be added to obtain a uniform phase state or a suspension emulsified state, but normally the two layers are subjected to the hydrothermal reaction as they are. You can The composition may contain a sufficient amount of water derived from the raw material, but if the raw material contains no or little water, water is added before being subjected to the hydrothermal reaction. There is a need.

The amount of water present in the system of hydrothermal reaction is the number of moles of water (the number of moles of water/the number of moles of water/the number of moles of zirconium oxide precursor or a salt containing zirconium (hereinafter, zirconium oxide precursor, etc.) present in the system). The number of moles of zirconium oxide precursor etc.) is preferably 4/1 to 100/1, and more preferably 8/1 to 50/1. If it is less than 4/1, the hydrothermal reaction may take a long time, or the obtained zirconium oxide particles may have a large particle size. On the other hand, if it exceeds 100/1, there is no particular problem except that the productivity decreases because the zirconium oxide precursor and the like are present in the system in small amounts.

The hydrothermal reaction is preferably performed at a pressure of 2 MPaG (gauge pressure) or less. The reaction proceeds even at 2 MPaG or more, but it is industrially unfavorable because the reactor becomes expensive. On the other hand, if the pressure is too low, the reaction progresses slowly, the particle size of the nanoparticles may increase due to the reaction for a long time, and zirconium oxide may have a plurality of crystal systems. It is preferable to carry out under the above pressure, more preferably 0.2 MPaG or more. The hydrothermal reaction time is, for example, about 2 to 24 hours.

When the zirconium oxide nanoparticles of the present invention are coated with a first carboxylic acid and an organic acid other than the first carboxylic acid, the zirconium oxide nanoparticles coated with the first carboxylic acid are first prepared. 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 the zirconium oxide nanoparticles coated with the first carboxylic acid and the organic acid. The mass ratio of 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. It is possible. The present invention also includes compositions containing zirconium oxide nanoparticles. The composition includes a dispersion liquid 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, etc. Of ethers; ethers 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); hydrocarbons such as benzene, toluene, xylene, ethylbenzene, trimethylbenzene, hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, mineral spirits; halogenated hydrocarbons such as dichloromethane, chloroform; dimethylformamide, N, Amides such as N-dimethylacetamide and N-methylpyrrolidone; water; oils such as mineral oil, vegetable oil, wax oil and silicone oil can be mentioned. One of these may be selected and used, or two or more thereof may be selected and mixed and used. From the viewpoint of handleability, a solvent having a boiling point of 40° C. or higher and 250° C. or lower at normal pressure is suitable, and ketones, modified ethers, etc. are suitable for resist applications described later.

The monofunctional monomer may be a compound having only one polymerizable carbon-carbon double bond, (meth)acrylic acid ester; styrene, p-tert-butylstyrene, α-methylstyrene, m-methylstyrene. , P-methylstyrene, p-chlorostyrene, p-chloromethylstyrene and other styrene-based monomers; (meth)acrylic acid and other carboxyl group-containing monomers; hydroxyethyl (meth)acrylate and other hydroxyl group-containing monomers The body etc. are mentioned. Specific examples of the (meth)acrylic acid ester include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth). (Meth)acrylic acid alkyl ester such as acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate; (meth)acryl such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate Acid cycloalkyl ester; aralkyl (meth)acrylic acid such as benzyl (meth)acrylate; (meth)acrylic acid ester having a glycidyl group such as glycidyl (meth)acrylate; and methyl (meth)acrylate is particularly preferable. .. 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, and dipropylene glycol di(meth)acrylate. (Meth)acrylate; neopentyl glycol poly(meth)acrylate such as neopentyl glycol di(meth)acrylate, dineopentyl glycol di(meth)acrylate; trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate Trimethylolpropane poly(meth)acrylates such as acrylates; polyfunctional (meth)acrylates such as pentaerythritol poly(meth)acrylates such as pentaerythritol tetra(meth)acrylate and dipentaerythritol hexa(meth)acrylate; divinylbenzene etc. Polyfunctional styrene-based monomers; polyfunctional allyl ester-based monomers such as diallyl phthalate, diallyl isophthalate, triallyl cyanurate, and triallyl isocyanurate.

The composition containing the above 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 above polymer (resin). When constituting the resin composition of the present invention, the polymer as 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, PEN; polyvinyl chlorides; polyvinylidene chlorides; polyvinyl acetates; polystyrenes; (meth)acrylic resin-based polymers; ABS resins; fluororesins; phenol/formalin resins, cresol/formalin resins Examples thereof include phenol resins; epoxy resins; amino resins such as urea resins, melamine resins and guanamine resins. Further, a soft resin or a hard resin such as a polyvinyl butyral resin, a polyurethane resin, an ethylene-vinyl acetate copolymer resin, an ethylene-(meth)acrylic acid ester copolymer resin, or the like is also included. Of the above, polyimides, polyurethanes, polyesters, (meth)acrylic resin-based 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 depending on the application, but when the composition is uncured or contains a polymer (resin), the composition is usually 90% by mass or less with respect to 100% by mass of all components (the total of all used components among the substitution-coated particles, solvent, monomer, oligomer, polymer, and polymer precursor described later). If it exceeds 90% by mass, it may be difficult to disperse uniformly and the uncured composition may become cloudy. On the other hand, the lower limit is not particularly limited, but is 1% by mass or more in consideration of the solvent cost. It is more preferably 5% by mass or more and 85% by mass or less, and further preferably 10% by mass or more and 80% by mass or less.

The resin composition of the present invention includes not only a composition of the above-mentioned polymer (polymer compound) and the zirconium oxide nanoparticles of the present invention, but also a monomer (polymer precursor) constituting the above-mentioned polymer, for example, A composition of a mixture of a dicarboxylic acid and a diamine, an unsaturated carboxylic acid such as acrylic acid or methacrylic acid or an ester compound thereof, and the zirconium oxide nanoparticles of the present invention is also included. Further, 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. Is also good.

Further, since the zirconium oxide nanoparticles of the present invention have remarkably excellent dispersibility, even if the composition (dispersion) has a high concentration, the composition has good transparency. A composition in which zirconium oxide nanoparticles are dispersed at a high concentration is advantageous for improving the refractive index, for example, and the refractive index can be adjusted according to various uses. 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 further preferably Is 60% by mass or more. The upper limit is not particularly limited, but the amount of zirconium oxide nanoparticles in the composition is preferably 90% by mass or less.

The resin composition of the present invention (including the curable composition after curing) may be blended with 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.

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

Zirconium oxide nanoparticles of the present invention, from good dispersibility, an antireflection film, a hard coat film, a brightness enhancement film, a prism film, a lenticular sheet, an optical film (or sheet) such as a microlens sheet, or an optical refractive index. Adjusting agent, optical adhesive, optical waveguide, lens, catalyst, CMP polishing composition, electrode, capacitor, ink jet recording method, piezoelectric element, LED/OLED/organic EL light extraction improving agent, antibacterial agent, dentistry It is suitable for use as an adhesive for automobiles and a light-concentrating structure used in solar cell panels. In addition to good dispersibility, it also suppresses changes in the crystal structure before and after firing, so it is a ceramic material such as a denture material. It can be preferably used for applications.

The zirconium oxide nanoparticles of the present invention have a stable crystal structure because yttrium is essential, and preferably further contains Al and at least one rare earth element other than yttrium. That is, when the zirconium oxide nanoparticles of the present invention are fired, changes in the crystal structure can be suppressed, and cracking and strength reduction due to the changes in the crystal structure can be suppressed. Moreover, since the zirconium oxide nanoparticles of the present invention are coated with the specific first carboxylic acid, they have good dispersibility in an organic medium, and a composition containing the zirconium oxide nanoparticles of the present invention is calcined. The resulting ceramic material has good ceramic properties such as translucency, toughness, and strength.

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. Alternatively, the zirconium oxide nanoparticles of the present invention can be obtained by firing a composition containing an additive such as alumina, spinel, YAG, mullite, or an aluminum borate compound. Further, the composition of the present invention comprising zirconium oxide nanoparticles and a binder can be obtained by firing. The firing temperature at this time may be about 500 to 1600°C. The calcination can be performed by a known method. Pressure may be applied to promote sintering during firing. The firing may be performed in air, an oxygen atmosphere, a mixed atmosphere of oxygen and air, or an inert atmosphere such as nitrogen or argon. Each can be appropriately selected depending on the application after firing.

Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the following examples, and of course, it is possible to carry out appropriate modifications within a range that can be adapted to the gist of the following description, and all of them are technical aspects of the present invention. 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 zirconium oxide particles 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: 50kV, 300mA
Sampling width: 0.0200°
Scan speed: 10.0000°/min
Measuring range: 10-75°
Measurement temperature: 25°C

(2) Quantification of the ratio of tetragonal and monoclinic crystals Based on the value calculated using an X-ray diffractometer (RINT-TTRIII, manufactured by Rigaku), reference is made using calculation software (PDXL, manufactured by Rigaku) It was quantified by the intensity ratio method (RIP method) (the attribution of peaks was also specified by the calculation software).

(3) Calculation of crystallite diameter by X-ray diffraction analysis The crystallite diameter of zirconium oxide particles 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). Calculation was performed using calculation software (PDXL manufactured by Rigaku Corporation).

(4) Measurement of weight (mass) reduction rate Using a TG-DTA (thermogravimetric-implied thermal analysis) device, the zirconium oxide particles coated at 10°C/min were heated from room temperature to 800°C in an air atmosphere, The weight (mass) reduction rate of the particles was measured. From the weight (mass) reduction rate, the proportion of the first carboxylic acid coating the zirconium oxide particles and the proportion of zirconium oxide can be known.

(5) Measurement of ¹ H-NMR The coated zirconium oxide particles were dispersed in deuterated chloroform to obtain a measurement sample, which was measured using "Unity Plus" (resonance frequency: 400 MHz, number of integration: 16 times) manufactured by Varian. .. The molar ratio of each compound was determined based on the integral ratio of the following chemical shift (based on tetramethylsilane) peaks.
i) 2-ethylhexanoic acid (1.0-0.5 ppm: 6H)
ii) Carboxylate derived from 2-ethylhexanoic acid (1.0-0.5 ppm: 6H)
iii) 2-acryloyloxyethyl succinic acid (6.7-5.7 ppm: 3H, 4.5-
(4.0 ppm: 4H)
iv) 3-methacryloxypropyltrimethoxysilane (6.5-5.5 ppm:2H, 4.5-4.0 ppm:2H, 4.0-3.5 ppm:9H, 1.0-0.5 ppm:2H )

(6) Fluorescent X-ray analysis The zirconium content and the yttrium content in the coated zirconium oxide particles were measured using a fluorescent X-ray analyzer (ZSX Primus II Rigaku Corporation).

Example 1
Preparation of coated yttria-stabilized zirconium oxide nanoparticles 1 (coated YSZ particles 1) coated with 2-ethylhexanoic acid and/or a carboxylate derived from 2-ethylhexanoic acid 2-ethylhexanoate zirconium mineral spirit solution ( 91.6 g, zirconium 2-ethylhexanoate content 44 mass%, manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.), and yttrium (III) 2-ethylhexanoate (1.3 g, yttrium content 7.9 mass%, Mitsu) Wako Chemical Co., Ltd.) and pure water (15.7 g) were mixed and charged into a 200 mL hydrothermal synthesis container. The container was heated to 190° C. and kept at that temperature for 16 hours for reaction. The pressure during hydrothermal synthesis was 1.3 MPaG (gauge pressure). After the reaction, the mixed liquid was taken out, and the precipitate accumulated at the bottom was filtered off to collect 15 g of a viscous solid. This viscous solid was placed in a beaker, washed with 75 g of methanol, and then filtered with a Kiriyama funnel. The obtained solid was dried at room temperature under reduced pressure, and methanol was removed to recover 11 g of white yttria-stabilized zirconium oxide nanoparticles 1 (coated YSZ particles 1).

When the crystal structure of the obtained coated YSZ particles 1 was confirmed, diffraction lines attributed to tetragonal crystals and monoclinic crystals were detected, and the ratio of tetragonal crystals to monoclinic crystals was 91/9 based on the intensity of the diffraction lines. The particle size (crystallite size) was 5 nm. Note that it is difficult to distinguish between cubic and tetragonal crystals by X-ray diffraction measurement, and even if cubic crystals are present, their proportion is counted as the proportion of tetragonal crystals.

Further, the mass reduction rate of the coated YSZ particles 1 measured according to the above-mentioned "(4) Measurement of weight (mass) reduction rate" was 14% by mass. Therefore, it was found that the 2-ethylhexanoic acid and/or the carboxylate derived from 2-ethylhexanoic acid coating the coated YSZ particles 1 was 14% by mass of the entire coated YSZ particles 1.

Further, the weight abundance ratio of zirconium and yttrium in the coated YSZ particles 1 measured according to the above-mentioned “(6) X-ray fluorescence analysis” was 99/1.

Example 2
Production of coated yttria-stabilized zirconium oxide nanoparticles 2 (coated YSZ particles 2) coated with 2-ethylhexanoic acid and/or a carboxylate derived from 2-ethylhexanoic acid Zirconium 2-ethylhexanoate mineral spirit solution ( 86.7 g, zirconium 2-ethylhexanoate content 44% by mass, manufactured by Daiichi Rare Element Chemical Industry Co., Ltd., and yttrium (III) 2-ethylhexanoate (4.8 g, yttrium content 7.9% by mass, Mitsu) Wako Chemical Co., Ltd.) and pure water (15.0 g) were mixed and charged in a 200 mL hydrothermal synthesis container. The container was heated to 190° C. and kept at that temperature for 16 hours for reaction. The pressure during hydrothermal synthesis was 1.3 MPaG (gauge pressure). After the reaction, the mixed liquid was taken out, and the precipitate accumulated at the bottom was filtered off to collect 15 g of a viscous solid. This viscous solid was placed in a beaker, washed with 75 g of methanol, and then filtered with a Kiriyama funnel. The obtained solid was dried at room temperature under reduced pressure, and methanol was removed to recover 11 g of white yttria-stabilized zirconium oxide nanoparticles 2 (coated YSZ particles 2).

When the crystal structure of the obtained coated YSZ particles 2 was confirmed, diffraction lines attributed to tetragonal crystals and monoclinic crystals were detected, and the ratio of tetragonal crystals to monoclinic crystals was 94/6 from the intensity of the diffraction lines. The particle size (crystallite size) was 4 nm.

Furthermore, the mass reduction rate of the coated YSZ particles 2 measured according to the above-mentioned “(4) Measurement of weight (mass) reduction rate” was 14 mass %. Therefore, it was found that the 2-ethylhexanoic acid and/or the carboxylate derived from 2-ethylhexanoic acid coating the coated YSZ particles 2 was 14% by mass of the entire coated YSZ particles 2.

Furthermore, the weight abundance ratio of zirconium to yttrium in the coated YSZ particles 2 measured according to the above-mentioned "(6) X-ray fluorescence analysis" was 95/4.

Example 3
Production of coated yttria-stabilized zirconium oxide nanoparticles 3 (coated YSZ particles 3) coated with 2-ethylhexanoic acid and/or a carboxylate derived from 2-ethylhexanoic acid Zirconium 2-ethylhexanoate mineral spirit solution ( 80.4 g, zirconium 2-ethylhexanoate content 44% by mass, manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.), and yttrium (III) 2-ethylhexanoate (11.7 g, yttrium content 7.9% by mass, Mitsu) Wako Chemical Co., Ltd.) and pure water (13.8 g) were mixed and charged in a 200 mL hydrothermal synthesis container. The container was heated to 190° C. and kept at that temperature for 16 hours for reaction. The pressure during hydrothermal synthesis was 1.3 MPaG (gauge pressure). After the reaction, the mixed solution was taken out, and the precipitate accumulated at the bottom was filtered off to collect 13 g of a viscous solid. The viscous solid was placed in a beaker, washed with 65 g of methanol, and then filtered with a Kiriyama funnel. The obtained solid was dried under reduced pressure at room temperature, and methanol was removed to recover 10 g of white yttria-stabilized zirconium oxide nanoparticles 3 (coated YSZ particles 3).

When the crystal structure of the obtained coated YSZ particles 3 was confirmed, diffraction lines attributed to tetragonal crystals and monoclinic crystals were detected, and the ratio of tetragonal crystals to monoclinic crystals was 100/0 based on the intensity of the diffraction lines. The particle size (crystallite size) was 4 nm.

Further, the mass reduction rate of the coated YSZ particles 3 measured according to the above-mentioned "(4) Measurement of weight (mass) reduction rate" was 15% by mass. Therefore, it was found that the 2-ethylhexanoic acid and/or the carboxylate derived from 2-ethylhexanoic acid coating the coated YSZ particles was 15% by mass of the entire coated YSZ particles 3.

Furthermore, the weight abundance ratio of zirconium to yttrium in the coated YSZ particles 3 measured according to the above-mentioned “(6) X-ray fluorescence analysis” was 91/9.

Example 4
Production of coated yttria-stabilized zirconium oxide nanoparticles 4 (coated YSZ particles 4) coated with 2-ethylhexanoic acid and/or a carboxylate derived from 2-ethylhexanoic acid Zirconium 2-ethylhexanoate mineral spirit solution ( 83.0 g, zirconium 2-ethylhexanoate content 44 mass%, manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.), and yttrium (III) 2-ethylhexanoate (6.3 g, yttrium content 7.9 mass%, Mitsu) Wako Chemical Co., Ltd.) and pure water (15.8 g) were mixed and charged into a 200 mL hydrothermal synthesis container. The container was heated to 190° C. and kept at that temperature for 8 hours for reaction. The pressure during hydrothermal synthesis was 1.4 MPaG (gauge pressure). After the reaction, the mixed solution was taken out, and the precipitate accumulated at the bottom was filtered off to collect 13 g of a viscous solid. This viscous solid was placed in a beaker, washed with 70 g of methanol, and then filtered with a Kiriyama funnel. The obtained solid was dried under reduced pressure at room temperature and methanol was removed to recover 10 g of white yttria-stabilized zirconium oxide nanoparticles 4 (coated YSZ particles 4).

When the crystal structure of the obtained coated YSZ particles 4 was confirmed, diffraction lines attributed to tetragonal crystals and monoclinic crystals were detected, and the ratio of tetragonal crystals to monoclinic crystals was 97/3 based on the intensity of the diffraction lines. The particle size (crystallite size) was 5 nm.

Furthermore, the mass reduction rate of the coated YSZ particles 4 measured according to the above-mentioned “(4) Measurement of weight (mass) reduction rate” was 17 mass %. Therefore, it was found that the 2-ethylhexanoic acid and/or the carboxylate derived from 2-ethylhexanoic acid coating the coated YSZ particles 4 was 17% by mass of the entire coated YSZ particles 4.

Further, the weight abundance ratio of zirconium to yttrium in the coated YSZ particles 4 measured according to the above-mentioned “(6) X-ray fluorescence analysis” was 95/5.

Comparative Example 1
Production of coated zirconium oxide nanoparticles (coated ZrO ₂ particles) coated with 2-ethylhexanoic acid and/or a carboxylate derived from 2-ethylhexanoic acid Zirconium 2-ethylhexanoate mineral spirit solution (90.4 g, Pure water (15.5 g) was mixed with zirconium 2-ethylhexanoate content 44% by mass, manufactured by Daiichi Rare Element Chemical Industry Co., Ltd. and charged in a 200 mL hydrothermal synthesis vessel. The container was heated to 190° C. and kept at that temperature for 16 hours for reaction. The pressure during hydrothermal synthesis was 1.3 MPaG (gauge pressure). After the reaction, the mixed solution was taken out, and the precipitate accumulated at the bottom was filtered off to collect 15 g of a wet cake. This viscous solid was placed in a beaker, washed with 75 g of methanol, and then filtered with a Kiriyama funnel. The obtained solid was dried at room temperature under reduced pressure, and methanol was removed to recover 11 g of white zirconium oxide nanoparticles (coated ZrO ₂ particles).

When the crystal structure of the obtained coated ZrO ₂ particles was confirmed, diffraction lines attributed to tetragonal crystals and monoclinic crystals were detected, and the ratio of tetragonal crystals to monoclinic crystals was 74/26 based on the intensity of the diffraction lines. The particle size (crystallite size) was 5 nm.

Furthermore, the mass reduction rate of the coated ZrO ₂ particles measured according to the above-mentioned “(4) Measurement of weight (mass) reduction rate” was 14 mass %. Therefore, it was found that the amount of 2-ethylhexanoic acid and/or 2-ethylhexanoic acid-derived carboxylate coating the coated zirconium oxide particles was 14% by mass of the entire coated zirconium oxide particles.

Example 5
Production of yttria-stabilized zirconium oxide nanoparticles 5 (coated YSZ particles 5) coated with 2-ethylhexanoic acid and/or a carboxylate derived from 2-ethylhexanoic acid and 2-acryloyloxyethylsuccinic acid Example 2 The coated YSZ particles 2 (10 g) obtained in Step 2 and 2-acryloyloxyethylsuccinic acid (1.5 g) were stirred in propylene glycol monomethyl ether acetate (12 g, hereinafter referred to as "PGMEA") until homogeneously dispersed. Mixed. Next, dispersed particles were aggregated by adding n-hexane (36 g) to make the solution cloudy, and the aggregated particles were separated from the cloudy liquid by filtration. Thereafter, the separated agglomerated particles are added to n-hexane (36 g), stirred for 10 minutes, the agglomerated particles are separated by filtration, and the obtained particles are vacuum dried at room temperature to give 2-ethylhexanoic acid and A yttria-stabilized zirconium oxide nanoparticle 5 (coated YSZ particle 5) surface-treated with a carboxylate derived from //2-ethylhexanoic acid and 2-acryloyloxyethylsuccinic acid was obtained.
The obtained coated YSZ particles 5 were dispersed in deuterated chloroform and used as measurement data, and analyzed by ¹ H-NMR. As a result, it was found that the existing molar ratio of 2-ethylhexanoic acid and/or carboxylate derived from 2-ethylhexanoic acid to 2-acryloyloxyethylsuccinic acid was 29:71.

Further, the mass reduction rate of the coated YSZ particles 5 measured according to the above-mentioned “(4) Measurement of weight (mass) reduction rate” was 18 mass %. Accordingly, 2-ethylhexanoic acid and/or 2-ethylhexanoic acid-derived carboxylate coating the coated zirconium oxide particles and 2-acryloyloxyethyl succinic acid account for 18% by mass of the entire coated zirconium oxide particles. I knew it was.

Example 6
Production of Inorganic Oxide Fine Particles-Containing Solution 1 By mixing the coated YSZ particles 5 (7 g) obtained in Example 5 and methyl ethyl ketone (3 g) and stirring until uniform, the inorganic oxide fine particles-containing solution 1 was obtained. Obtained.

Example 7
Production of Inorganic Oxide Fine Particle-Containing Solution 2 The coated YSZ particles 5 (7 g) obtained in Example 5, methyl ethyl ketone (3 g) and phosphate ester KAYAMER PM-21 (manufactured by Nippon Kayaku Co., Ltd., 0.1 g) were blended. Then, the solution 2 containing inorganic oxide fine particles was obtained by stirring until uniform.

Example 8
Preparation of yttria-stabilized zirconium oxide nanoparticles 6 (coated YSZ particles 6) coated with 2-ethylhexanoic acid and/or a carboxylate derived from 2-ethylhexanoic acid and 3-methacryloxypropyltrimethoxysilane Example 2 The coated yttria-stabilized zirconium oxide nanoparticles 2 (10 g) obtained in 1 above were dispersed in methyl isobutyl ketone (40 g) to prepare a cloudy slurry. Add 3-methacryloxypropyltrimethoxysilane (1.0 g, Shin-Etsu Chemical Co., Ltd., KBM-503) and water (0.9 g) as a surface treatment agent to the solution, and heat and reflux at 80° C. for 1 hour. A transparent dispersion solution was obtained. Then, n-hexane was added to agglomerate the dispersed particles to make the solution cloudy. After the aggregated particles are separated from the cloudy liquid by filtration, they are heated and dried at room temperature, and stabilized with yttria coated with 2-ethylhexanoic acid and/or a carboxylate derived from 2-ethylhexanoic acid and 3-methacryloxypropyltrimethoxysilane. Zirconium oxide nanoparticles 6 (coated YSZ particles 6) were prepared.

By TG-DTA (thermogravimetric-implication thermal analysis) of the obtained coated YSZ particles 5, the mass reduction rate of the coated YSZ particles 5 when the temperature was raised to 800°C at a rate of 10°C/min in an air atmosphere. When measured, the reduction rate was 15% by mass. From this, it was confirmed that the organic content of the coated YSZ particles 6 was 15% by mass.

The obtained coated YSZ particles 6 were dispersed in deuterated chloroform and used as a measurement data, and analyzed by ¹ H-NMR. As a result, it was found that the existing molar ratio of 2-ethylhexanoic acid and/or carboxylate derived from 2-ethylhexanoic acid to 3-methacryloxypropyltrimethoxysilane was 59:41.

Example 9
Production of Inorganic Oxide Fine Particles-Containing Solution 3 The coated YSZ particles 6 (7 g) obtained in Example 8 and methyl ethyl ketone (3 g) were mixed and stirred until the mixture became uniform, whereby the inorganic oxide fine particles-containing solution 3 was obtained. Obtained.

Example 10
Production of Inorganic Oxide Fine Particle-Containing Solution 4 The coated YSZ particles 6 (7 g) obtained in Example 8, methyl ethyl ketone (3 g), and phosphoric acid ester Phoslex A-208 (1 g, manufactured by SC Organic Chemical Co., Ltd.) were blended and uniformly mixed. The solution 4 containing inorganic oxide fine particles was obtained by stirring until it became.

Example 11
Production of benzyl acrylate dispersion of coated YSZ particles 6 Benzyl acrylate (7 g, manufactured by Hitachi Chemical Co., Ltd.) was added to the inorganic oxide particle-containing solution 4 (10 g) obtained in Example 10 and stirred until uniform. While stirring was continued, methyl ethyl ketone was removed under 50° C./reduced pressure conditions to obtain 14 g of a benzyl acrylate dispersion of coated YSZ particles 6.

Example 12
Production of Inorganic Oxide Fine Particle-Containing Composition Inorganic oxide fine particle-containing composition was obtained by adding 0.02 g of Irgacure 184 to 1 g of the benzyl acrylate dispersion of the coated YSZ particles 6 and stirring until uniform.

Example 13
Production of Inorganic Oxide Fine Particle-Containing Transparent Cured Film The inorganic oxide-containing composition obtained in Example 12 was placed on a glass substrate, a 100 μm film was applied with an applicator, and UV cured to obtain inorganic oxide fine particles. A contained transparent cured film was obtained.

Example 14
Change in Crystal System of Coated YSZ Particles 1 Before and After Firing The coated YSZ particles 1 (1 g, tetragonal/monoclinic=91/9) obtained in Example 1 were weighed in a combustion boat and heated at 1000° C. Baked for 3 hours. When the crystal structure of the ash content of the recovered coated YSZ particles 1 was confirmed, it was tetragonal/monoclinic=28/72.

Example 15
Change in Crystal System of Coated YSZ Particles 2 Before and After Firing The coated YSZ particles 2 (1 g, tetragonal crystal/monoclinic crystal=94/6) obtained in Example 2 were weighed in a combustion boat and heated at 1000° C. Baked for 3 hours. When the crystal structure of the ash content of the recovered coated YSZ particles 2 was confirmed, it was tetragonal/monoclinic=98/2, and it was confirmed that the crystal system hardly changed.

Example 16
Change in Crystal System of Coated YSZ Particles 3 Before and After Firing The coated YSZ particles 3 (1 g, tetragonal/monoclinic=100/0) obtained in Example 3 were weighed in a combustion boat and heated at 1000° C. Baked for 3 hours. When the crystal structure of the ash content of the recovered coated YSZ particles 3 was confirmed, it was tetragonal crystal/monoclinic crystal=100/0, and it was confirmed that the crystal system did not change at all.

Comparative example 2
Change in Crystal System of Coated ZrO ₂ Particles Before and After Firing The coated ZrO ₂ particles (1 g, tetragonal/monoclinic=74/26) obtained in Comparative Example 1 were weighed in a combustion boat and heated at 1000° C. Baked for 3 hours. When the crystal structure of the ash content of the recovered coated ZrO ₂ particles was confirmed, it was tetragonal/monoclinic=12/88, and it was confirmed that the crystal system was greatly changed.

Claims (9)

A zirconium oxide nanoparticle coated with a first carboxylic acid, which is a secondary carboxylic acid having 5 to 18 carbon atoms ,
The zirconium oxide nanoparticles contain yttrium and , if necessary, at least one of Al and a rare earth element (other than yttrium),
Of Al and rare earth elements (including yttrium), the yttrium content is 0.5% by mass or more when only yttrium is contained, and the total amount of Al and rare earth elements is at least one yttrium other than yttrium. Content is 0.5 mass% or more, zirconium oxide nanoparticles. The zirconium oxide nanoparticles according to claim 1, which are coated with at least one of an organic acid other than the first carboxylic acid, a silane coupling agent, a surfactant, and an organic phosphorus compound. Dispersion containing zirconium oxide nanoparticles according to claim 1 or 2. Resin composition comprising a zirconium oxide nanoparticles according to claim 1 or 2. Molding material comprising zirconium oxide nanoparticles according to claim 1 or 2. Ceramic material obtained from zirconium oxide nanoparticles according to claim 1 or 2. A method for producing a ceramic material, comprising firing the zirconium oxide nanoparticles according to claim 1 or 2 at 500° C. or higher. A method for producing a ceramic material, comprising: firing the composition containing the zirconium oxide nanoparticles according to claim 1 or 2 at 500° C. or higher. The method for producing zirconium oxide nanoparticles according to claim 1 or 2 , wherein
A first carboxylic acid, which is a secondary carboxylic acid having 5 to 18 carbon atoms , and a zirconium raw material composed of zirconium or a zirconium-containing compound,
An Al or rare earth element raw material composed of the first carboxylic acid and at least one of Al, a rare earth element (including yttrium) , an Al-containing compound and a rare earth element (including yttrium) -containing compound,
A method for producing zirconium oxide nanoparticles, which comprises performing hydrothermal synthesis without using MgSO ₄ .