JP2024002087A - metal oxide dispersion - Google Patents

Abstract

To provide a metal oxide dispersion having excellent stability over time and suppressing generation of a solvent shock.SOLUTION: A metal oxide dispersion according to the present invention comprises: a first carboxylic acid which is at least one kind of aromatic carboxylic acid selected from the group consisting of an aromatic carboxylic acid having an aromatic ring substituted with an alkyl group, an aromatic carboxylic acid having an aromatic ring substituted with an alkoxy group, an aromatic carboxylic acid having an aromatic ring substituted with an alkoxycarbonyl group, and an aromatic carboxylic acid having an aromatic ring substituted with an acyloxy group; metal oxide nanoparticles surface-treated with a capping agent; and a solvent. The capping agent comprises a second carboxylic acid having an ester bond and a polymerizable double bond. The second carboxylic acid is different from the first carboxylic acid.SELECTED DRAWING: None

Description

The present invention relates to metal oxide dispersions.

A metal oxide film used for a hard mask or the like can be formed by forming a metal oxide dispersion liquid by a liquid phase coating method such as a spin coating method or an inkjet method. As metal oxide dispersions, coating compositions containing, for example, an organic solvent, metal oxide nanoparticles dispersed in this organic solvent, and a high carbon polymer with a specific structure dissolved in this solvent are known (Patent Document 1).

Special Publication No. 2020-503409

In devices that apply metal oxide dispersions, solvents such as butyl acetate or γ-butyrolactone are used in processes such as pipe cleaning and pre-wetting. In this case, the metal oxide dispersion is required to be prevented from becoming cloudy or forming a precipitate over time due to the addition of the above-mentioned solvent, that is, the occurrence of solvent shock. On the other hand, the metal oxide dispersion itself is also required to have excellent stability over time.

The present invention has been made in view of such conventional circumstances, and an object of the present invention is to provide a metal oxide dispersion having excellent stability over time and suppressing the occurrence of solvent shock.

The present inventors have conducted extensive research to solve the above problems. As a result, a metal oxide dispersion containing a first carboxylic acid that is a predetermined aromatic carboxylic acid, metal oxide nanoparticles whose surface has been treated with a capping agent, and a solvent, the metal oxide dispersion containing the capping agent has found that the above problem can be solved by a metal oxide dispersion containing a second carboxylic acid having an ester bond and a polymerizable double bond, the second carboxylic acid being different from the first carboxylic acid. , we have completed the present invention. Specifically, the present invention provides the following.

One aspect of the present invention is
Aromatic carboxylic acids having aromatic rings substituted with alkyl groups, aromatic carboxylic acids having aromatic rings substituted with alkoxy groups, aromatic carboxylic acids having aromatic rings substituted with alkoxycarbonyl groups, and acyloxy groups. a first carboxylic acid that is at least one aromatic carboxylic acid selected from the group consisting of aromatic carboxylic acids having a substituted aromatic ring;
metal oxide nanoparticles surface-treated with a capping agent;
solvent and
A metal oxide dispersion containing,
The capping agent includes a second carboxylic acid having an ester bond and a polymerizable double bond,
The second carboxylic acid is a metal oxide dispersion liquid different from the first carboxylic acid.

According to the present invention, it is possible to provide a metal oxide dispersion that has excellent stability over time and suppresses the occurrence of solvent shock.

<Metal oxide dispersion>
The metal oxide dispersion according to the present invention includes an aromatic carboxylic acid having an aromatic ring substituted with an alkyl group, an aromatic carboxylic acid having an aromatic ring substituted with an alkoxy group, and an aromatic ring substituted with an alkoxycarbonyl group. and an aromatic carboxylic acid having an aromatic ring substituted with an acyloxy group. the capping agent contains a second carboxylic acid having an ester bond and a polymerizable double bond, and the second carboxylic acid contains treated metal oxide nanoparticles and a solvent. It is different from the carboxylic acid in No. 1. The metal oxide dispersion according to the present invention has excellent stability over time and suppresses the occurrence of solvent shock.

In the solid content of the metal oxide dispersion, the ratio of the inorganic mass to the total of the inorganic mass and the organic mass is 25% by mass or more, preferably 30% by mass or more, and more preferably 40% by mass or more. It is. When the ratio is within the above range, the ratio of the inorganic component mass can be set high, and as a result, the ratio of the inorganic component mass can be easily increased in the metal oxide dispersion. The upper limit of the ratio is not particularly limited, and may be 90% by mass, 80% by mass, or 75% by mass.

[First carboxylic acid]
The first carboxylic acid is an aromatic carboxylic acid having an aromatic ring substituted with an alkyl group, an aromatic carboxylic acid having an aromatic ring substituted with an alkoxy group, and an aromatic carboxylic acid having an aromatic ring substituted with an alkoxycarbonyl group. At least one aromatic carboxylic acid selected from the group consisting of carboxylic acid and aromatic carboxylic acid having an aromatic ring substituted with an acyloxy group. The first carboxylic acid may be used alone or in combination of two or more.

The aromatic ring possessed by the aromatic carboxylic acid belonging to the first carboxylic acid is not particularly limited, and includes, for example, a benzene ring, a naphthalene ring, an anthracene ring, a biphenyl ring, etc., which improves stability over time and prevents solvent shock. From the viewpoint of suppressing generation, etc., a benzene ring is preferred.

The alkyl group may be linear or branched, and includes, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, an n-pentyl group, and an isopentyl group. Examples include alkyl groups having 1 to 18 carbon atoms, such as sec-pentyl group, tert-pentyl group, n-hexyl group, isohexyl group, sec-hexyl group, and tert-hexyl group; An alkyl group having 8 or more carbon atoms is preferable, and an alkyl group having 3 or more and 6 or less carbon atoms is more preferable.

The alkyl group contained in the alkoxy group is the same as above.

The alkyl group contained in the alkoxycarbonyl group is the same as above.

Examples of the acyloxy group include acyloxy groups having 1 to 18 carbon atoms such as formyloxy group, acetyloxy group, propionyloxy group, n-butyryloxy group, isobutyryloxy group, and benzoyloxy group, An acyloxy group having 2 to 8 carbon atoms is preferred, and an acyloxy group having 3 to 6 carbon atoms is more preferred.

Specific examples of the first carboxylic acid include 4-methylbenzoic acid, 4-ethylbenzoic acid, 4-n-propylbenzoic acid, 4-n-butylbenzoic acid, 4-n-pentylbenzoic acid, 4-n- -Hexylbenzoic acid, 4-methoxybenzoic acid, 4-ethoxyethylbenzoic acid, 4-n-propoxybenzoic acid, 2-n-propoxybenzoic acid, 4-n-butoxybenzoic acid, 4-(n-hexyloxy) Examples include benzoic acid, 4-n-pentyl-4'-biphenylcarboxylic acid, and mono-n-hexyl phthalate.From the viewpoint of improving stability over time and suppressing the occurrence of solvent shock, 4-n-propylbenzoic acid, 4-n-butylbenzoic acid, 4-n-pentylbenzoic acid, 4-n-hexylbenzoic acid, 4-n-propoxybenzoic acid, 2-n-propoxybenzoic acid, 4-n-butoxybenzoic acid, 4- (n-hexyloxy)benzoic acid, 4-n-pentyl-4'-biphenylcarboxylic acid, and mono-n-hexyl phthalate are preferred.

The amount of the first carboxylic acid used is not particularly limited, and is preferably 1 to 20% by mass, more preferably 3 to 15% by mass, based on the total of components other than the solvent in the metal oxide dispersion. , even more preferably 5 to 10% by weight. When the amount of the first carboxylic acid used is within the above range, the stability of the metal oxide dispersion liquid over time is likely to be improved, and the occurrence of solvent shock is likely to be suppressed.

A first carboxylic acid is present in the metal oxide dispersion separately from the metal oxide nanoparticles and/or in the capping agent. That is, the first carboxylic acid may cover the metal oxide nanoparticles like the capping agent, or may exist in a free state in the metal oxide dispersion.

The ratio of the mass of the first carboxylic acid present in the metal oxide dispersion separately from the metal oxide nanoparticles to the mass of the solid content of the metal oxide dispersion is 10 mass or less. The amount is preferably 1 to 9% by weight, more preferably 1 to 9% by weight, and even more preferably 3 to 8% by weight. When the ratio is within the above range, the metal oxide dispersion liquid tends to have improved stability over time, and the occurrence of solvent shock is likely to be suppressed.

[Metal oxide nanoparticles surface treated with capping agent]
The metal oxide dispersion includes metal oxide nanoparticles that are surface treated with a capping agent. As used herein, metal oxide nanoparticles consist of a metal oxide and do not contain a capping agent. The capping agent includes a second carboxylic acid having an ester bond and a polymerizable double bond, and the second carboxylic acid is different from the first carboxylic acid. The metal oxide nanoparticles surface-treated with a capping agent may be used alone or in combination of two or more. When the metal oxide dispersion liquid contains metal oxide nanoparticles that have been surface-treated with a capping agent, the stability of the metal oxide dispersion liquid over time is likely to improve, and the occurrence of solvent shock is likely to be suppressed.

The average particle diameter of the metal oxide nanoparticles is preferably 5 nm or less, more preferably 4 nm or less, and even more preferably 3 nm or less. The lower limit of the average particle diameter of the metal oxide nanoparticles is not particularly limited, and may be, for example, 0.5 nm or more, 1 nm or more, or 2 nm or more. When the average particle diameter of the metal oxide nanoparticles is within the above range, the stability of the metal oxide dispersion liquid over time is more likely to be improved, and the occurrence of solvent shock is more likely to be suppressed. In this specification, the average particle diameter of metal oxide nanoparticles refers to XRD measurement performed using an X-ray diffraction device (SmartLab, manufactured by Rigaku Co., Ltd.), and the obtained results are analyzed using the attached software PDXL. - Refers to the value determined using the Wagner method.

The average particle diameter of the metal oxide nanoparticles surface-treated with a capping agent is preferably 10 nm or less, more preferably 8 nm or less, and even more preferably 6 nm or less. The lower limit is not particularly limited, and may be, for example, 0.5 nm or more, 1 nm or more, or 2 nm or more. As used herein, the average particle diameter of metal oxide nanoparticles surface-treated with a capping agent refers to a value measured using a dynamic light scattering (DLS) device such as Malvern Zetasizer Nano S.

The metals contained in the metal oxide nanoparticles are not particularly limited, and include, for example, zinc, yttrium, hafnium, zirconium, lanthanum, cerium, neodymium, gadolinium, holmium, lutetium, tantalum, titanium, silicon, aluminum, antimony, and tin. , indium, tungsten, copper, vanadium, chromium, niobium, molybdenum, ruthenium, rhodium, rhenium, iridium, germanium, gallium, thallium, and magnesium.From the viewpoint of film formability and stability, hafnium, zirconium, titanium , and tin are preferred, and zirconium is more preferred. The above metals may be used alone or in combination of two or more.

The metal oxide nanoparticles may be composed of metal atoms and oxygen atoms, or may be composed of metal atoms, oxygen atoms, and atoms other than metal atoms and oxygen atoms. Examples of atoms other than metal atoms and oxygen atoms include nitrogen atoms. Therefore, the metal oxide nanoparticles may be made of a metal oxide, a metal oxynitride, or the like.

In the metal oxide dispersion according to the present invention, it is presumed that part or all of the surfaces of the metal oxide nanoparticles are covered with a capping agent. The capping agent includes a second carboxylic acid having an ester bond and a polymerizable double bond, and the second carboxylic acid is different from the first carboxylic acid. In the metal oxide dispersion according to the present invention, when the metal oxide nanoparticles are surface-treated with the above-mentioned capping agent, the metal oxide nanoparticles tend to have stable dispersibility in a solvent, and The stability of the dispersion liquid over time is more likely to be improved, and the occurrence of solvent shock is more likely to be suppressed.

The second carboxylic acid is not particularly limited as long as it has an ester bond and a polymerizable double bond. For example, one hydroxy group in the polyol and one carboxy group in the polycarboxylic acid form an ester bond. and in which another hydroxy group in the polyol and a carboxy group in (meth)acrylic acid form an ester bond; more specifically, ethylene glycol One hydroxy group in a diol such as succinic acid, one carboxy group in a dicarboxylic acid such as phthalic acid forms an ester bond, and another hydroxy group in the diol (meth) forms an ester bond. ) Examples include carboxylic acids in which the carboxy group in acrylic acid forms an ester bond. The second carboxylic acid may be used alone or in combination of two or more.

The second carboxylic acid may have an aromatic ring. When the second carboxylic acid has an aromatic ring, the occurrence of solvent shock in the metal oxide dispersion is likely to be suppressed. The aromatic ring is not particularly limited, and includes, for example, a benzene ring, a naphthalene ring, an anthracene ring, a biphenyl ring, etc., and a benzene ring is preferred from the viewpoint of reactivity with the capping agent and metal oxide nanoparticles.

Specific examples of the second carboxylic acid include 2-acryloyloxyethyl phthalic acid, 2-methacryloyloxyethyl phthalic acid, 2-acryloyloxyethylsuccinic acid, 2-methacryloyloxyethylsuccinic acid, etc. From the viewpoint of reactivity with metal oxide nanoparticles and metal oxide nanoparticles, 2-acryloyloxyethyl phthalic acid and 2-acryloyloxyethyl succinic acid are preferred.

The capping agent may also include other capping agents. Examples of other capping agents include at least one selected from the group consisting of alkoxysilanes, phenols, alcohols, carboxylic acids other than the second carboxylic acid, and carboxylic acid halides. Specific examples of other capping agents include n-propyltrimethoxysilane, n-propyltriethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, n-dodecyltrimethoxysilane, and n-dodecyltriethoxysilane. Silane, n-hexadecyltrimethoxysilane, n-hexadecyltriethoxysilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenethylphenyltrimethoxysilane, phenethyl ethyl Triethoxysilane, 3-{2-methoxy[poly(ethyleneoxy)]}propyltrimethoxysilane, 3-{2-methoxy[poly(ethyleneoxy)]}propyltriethoxysilane, 3-{2-methoxy[trimethoxysilane] (ethyleneoxy)]}propyltrimethoxysilane, 3-{2-methoxy[tri(ethyleneoxy)]}propyltriethoxysilane, vinyltrimethoxylane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, 1-hexenyltrimethoxysilane, 1-hexenyltriethoxysilane, 1-octenyltrimethoxysilane, 1-octenyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyl Trimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-acryloylpropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-isocyane Alkoxysilanes such as natopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane; Phenols such as phenol; ethanol, n- Alcohols without unsaturated groups such as propanol, isopropanol, n-butanol, n-heptanol, n-hexanol, n-octanol, n-dodecyl alcohol, n-octadecanol, benzyl alcohol, and triethylene glycol monomethyl ether; Alcohols containing unsaturated groups such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, allyl alcohol, oleyl alcohol, ethylene glycol monoallyl ether, propylene glycol monoallyl ether, and 3-allyloxypropanol ; Acids such as octanoic acid, acetic acid, propionic acid, 2-[2-(methoxyethoxy)ethoxy]acetic acid, oleic acid, lauric acid, benzoic acid; and acid halides of these acids, such as acid chlorides of these acids; Preferred examples include alkoxysilanes, unsaturated group-containing alcohols, and the compounds listed as acids. The other capping agents mentioned above may be used alone or in combination of two or more.

The amount of capping agent used when surface treating metal oxide nanoparticles with a capping agent is not particularly limited. Preferably, a sufficient amount of capping agent is used to react with substantially all of the hydroxy groups on the surface of the metal oxide nanoparticles.

The content of metal oxide nanoparticles in the metal oxide dispersion is not particularly limited as long as it does not impede the object of the present invention, and is 5% by mass based on the total of components other than the solvent in the metal oxide dispersion. The content is preferably 99% by mass or less, more preferably 30% by mass or more and 98% by mass or less, and even more preferably 60% by mass or more and 97% by mass or less. When the content is within the above range, the metal oxide dispersion liquid tends to have improved stability over time, and the occurrence of solvent shock is likely to be suppressed. Note that the above content of the metal oxide nanoparticles includes the content of the capping agent present on the surface of the metal oxide nanoparticles.

[solvent]
The metal oxide dispersion according to the present invention contains a solvent for the purpose of adjusting coating properties and viscosity. As the solvent, typically an organic solvent is used. The type of organic solvent is not particularly limited as long as it can uniformly dissolve or disperse the components contained in the metal oxide dispersion.

Suitable examples of organic solvents that can be used as the solvent include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol-n-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, Diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol Mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether (Poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, etc. (Poly)alkylene glycol monoalkyl ether acetates; Other ethers such as diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, and tetrahydrofuran; Ketones such as methyl ethyl ketone, cyclohexanone, 2-heptanone, and 3-heptanone; 2-hydroxy Lactic acid alkyl esters such as methyl propionate and ethyl 2-hydroxypropionate; ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, 3 - Ethyl ethoxypropionate, ethyl ethoxy acetate, ethyl hydroxy acetate, 2-hydroxy-3-methyl moiety methyl carbonate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl formate, isopentyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate, methyl pyruvate, Other esters such as ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, and ethyl 2-oxobutanoate; Aromatic hydrocarbons such as toluene and xylene; N-methylpyrrolidone, N,N- Examples include amides such as dimethylformamide and N,N-dimethylacetamide. These organic solvents can be used alone or in combination of two or more.

The amount of solvent used in the metal oxide dispersion according to the present invention is not particularly limited. From the viewpoint of coating properties of the metal oxide dispersion, the amount of the solvent used is, for example, 30 to 99.9% by mass, preferably 50 to 98% by mass, based on the entire metal oxide dispersion. .

[Surfactant]
The metal oxide dispersion according to the present invention may further contain a surfactant (surface conditioner) in order to improve coating properties, antifoaming properties, leveling properties, and the like. The surfactants may be used alone or in combination of two or more. Examples of the surfactant include silicone surfactants, fluorine surfactants, and polymer wetting and dispersing agents.

Specifically, the silicone surfactants include BYK-077, BYK-085, BYK-300, BYK-301, BYK-302, BYK-306, BYK-307, BYK-310, BYK-320, BYK -322, BYK-323, BYK-325, BYK-330, BYK-331, BYK-333, BYK-335, BYK-341, BYK-344, BYK-345, BYK-346, BYK-348, BYK-354 , BYK-355, BYK-356, BYK-358, BYK-361, BYK-370, BYK-371, BYK-375, BYK-380, BYK-390 (manufactured by BYK Chemie).

Specifically, the fluorine-based surfactants include F-114, F-177, F-410, F-411, F-450, F-493, F-494, F-443, F-444, -445, F-446, F-470, F-471, F-472SF, F-474, F-475, F-477, F-478, F-479, F-480SF, F-482, F-483 , F-484, F-486, F-487, F-172D, MCF-350SF, TF-1025SF, TF-1117SF, TF-1026SF, TF-1128, TF-1127, TF-1129, TF-1126, TF -1130, TF-1116SF, TF-1131, TF-1132, TF-1027SF, TF-1441, TF-1442 (manufactured by DIC); Polyfox series PF-636, PF-6320, PF-656, PF- 6520 (manufactured by Omnova) and the like.

Specifically, the polymer wetting and dispersing agent includes BYK-140, BYK-145, BYK-161, BYK-162, BYK-163, BYK-164, BYK-167, BYK-168, BYK-170, BYK -171, BYK-174, BYK-180, BYK-182, BYK-184, BYK-185, BYK-2050, BYK-2055, BYK-2015, BYK-9077 (manufactured by BYK Chemie), and the like.

The amount of surfactant used is not particularly limited, and from the viewpoint of coating properties, antifoaming properties, leveling properties, etc. of the metal oxide dispersion, the amount of surfactant used is, for example, based on the total of components other than the solvent in the metal oxide dispersion. The amount is 0.01 to 2% by weight, preferably 0.05 to 1% by weight.

[Other ingredients]
The metal oxide dispersion according to the present invention may contain a dispersant, a thermal polymerization inhibitor, an antifoaming agent, a silane coupling agent, a coloring agent (pigment, dye), a crosslinking agent, an acid generator, etc., as necessary. Additives can be included. Conventionally known additives can be used for any of the additives. Examples of surfactants include anionic, cationic, and nonionic compounds; thermal polymerization inhibitors include hydroquinone and hydroquinone monoethyl ether; and antifoaming agents include silicone and fluorine compounds. Examples include compounds.

The method for producing the metal oxide dispersion according to the present invention is not particularly limited. For example, the first carboxylic acid, metal oxide nanoparticles surface-treated with a capping agent, a solvent, and optionally a surface-active Examples include a method of uniformly mixing the agent and optionally other components.

<Method for manufacturing metal oxide film>
Examples of the method for producing a metal oxide film include a production method including a coating film forming step of forming a coating film made of the metal oxide dispersion according to the present invention.

The coating film can be formed, for example, by applying a metal oxide dispersion onto a substrate such as a semiconductor substrate. Coating methods include contact transfer coating devices such as roll coaters, reverse coaters, and bar coaters, and non-contact coating devices such as spinners (rotary coating devices, spin coaters), dip coaters, spray coaters, slit coaters, and curtain flow coaters. A method using a coating device may be mentioned.

The substrate preferably includes a metal film, a metal carbide film, a metal oxide film, a metal nitride film, or a metal oxynitride film. Examples of the metal constituting the substrate include silicon, titanium, tungsten, hafnium, zirconium, chromium, germanium, copper, aluminum, indium, gallium, arsenic, palladium, iron, tantalum, iridium, molybdenum, and alloys thereof. However, it is preferable that silicon, germanium, and gallium are included. Further, the surface of the substrate may have an uneven shape, and the uneven shape may be a patterned organic material.

Then, if necessary, volatile components such as solvents are removed and the coating film is dried. The drying method is not particularly limited, and examples include a method of drying on a hot plate at a temperature of 80° C. or higher and 140° C. or lower, preferably 90° C. or higher and 130° C. or lower, for a period of 60 seconds or more and 150 seconds or less. . Before heating with a hot plate, vacuum drying may be performed at room temperature using a vacuum drying device (VCD).

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Preparation of metal oxide dispersion]
The following dispersion stock solutions were prepared with reference to the description in paragraph [0223] of JP 2018-193481A.

- Preparation of Z-1 dispersion stock solution Based on the description in paragraph [0223] of JP 2018-193481A, a slurry of ZrO ₂ obtained by cooling to room temperature was centrifuged to obtain wet cake A. 2-acryloyloxyethylphthalic acid in an amount of 0.25 times the weight of wet cake A was added to wet cake A and stirred. After reprecipitation, wet cake B was obtained by centrifugation. Wet cake B was dried under reduced pressure overnight to obtain a powder. To the obtained dry powder, propylene glycol monomethyl ether acetate (hereinafter referred to as "PGMEA") was added and redispersed so that the solid content concentration was 48% by mass, and then filtered to obtain the Z-1 dispersion stock solution. I got it.

-Measurement of the size of metal oxide nanoparticles contained in the Z-1 dispersion stock solution Using the Z-1 dispersion stock solution as a sample, XRD measurement was performed using an X-ray diffraction device (SmartLab, manufactured by Rigaku Co., Ltd.). The obtained results were analyzed using the attached software PDXL, and the size (crystallite size) of the metal oxide nanoparticles was determined using the Halder-Wagner method, and was found to be 2.5 nm.

・Preparation of Z-2 dispersion stock solution Perform the same procedure as in "Preparation of Z-1 dispersion stock solution" above, except that 2-acryloyloxyethyl phthalic acid was changed to 2-acryloyloxyethylsuccinic acid (see the formula below). A Z-2 dispersion stock solution was obtained.

・Measurement of the size of metal oxide nanoparticles contained in the Z-2 dispersion stock solution Except for using the Z-2 dispersion stock solution in place of the Z-1 dispersion stock solution, When the same operation as in "Measurement of Size of Metal Oxide Nanoparticles" was performed, the size of metal oxide nanoparticles (crystallite size) was 2.5 nm.

・Preparation of Z-3 dispersion stock solution 2-acryloyloxyethylsuccinic acid in an amount of 0.25 times the weight of wet cake A, 2-acryloyloxyethyl phthalic acid in an amount of 0.125 times the weight of wet cake A, and 2-acryloyloxyethyl succinic acid in an amount of 0.25 times the weight of wet cake A A Z-3 dispersion stock solution was obtained by performing the same procedure as in "Preparation of Z-1 dispersion stock solution" above, except for changing the amount of 4-(n-hexyloxy)benzoic acid to 0.125 times the weight. .

・Measurement of the size of metal oxide nanoparticles contained in the Z-3 dispersion stock solution. When the same operation as in "Measurement of Size of Metal Oxide Nanoparticles" was performed, the size of metal oxide nanoparticles (crystallite size) was 2.5 nm.

- Preparation of carboxylic acid solutions 0.40 parts by mass of the carboxylic acids shown in Table 1 and 99.60 parts by mass of PGMEA were mixed to obtain carboxylic acid solutions A to K.

The carboxylic acid solution and the solvent PGMEA are sequentially added to the Z-1 dispersion stock solution, Z-2 dispersion stock solution, or Z-3 dispersion stock solution at the proportions shown in Table 2 or 3 (unit: parts by mass) and stirring, A metal oxide dispersion was obtained by filtration with a membrane filter having a diameter of 0.2 μm.

[Ratio of inorganic mass]
In Table 2 or 3, the "ratio of inorganic mass" indicates the ratio of the inorganic mass to the total of the inorganic mass and the organic mass of the solid content of the metal oxide dispersion. Specifically, the Z-1 dispersion liquid, Z- The proportion (mass %) of the inorganic content of the 2 dispersion liquid or the Z-3 dispersion liquid was calculated.

[Ratio of free aromatic carboxylic acid]
In Table 2 or 3, the "proportion of free aromatic carboxylic acid" refers to the percentage of free aromatic carboxylic acid that exists in the metal oxide dispersion separately from the metal oxide nanoparticles, based on the mass of the solid content of the metal oxide dispersion. It shows the proportion of aromatic carboxylic acids in Specifically, the amount of carboxylic acid in the carboxylic acid solution relative to the sum of the mass of carboxylic acid in the carboxylic acid solution and the solid mass of the Z-1 dispersion, Z-2 dispersion, or Z-3 dispersion The mass ratio (mass %) was calculated.

[Stability over time]
The metal oxide dispersion that was allowed to stand still in the container at room temperature for 6 months was carefully visually observed and evaluated using the following criteria. The results are shown in Table 2 or 3.
+ (Good): Neither cloudiness of the entire dispersion nor precipitation at the bottom of the container was observed.
- (Poor): White turbidity of the entire dispersion, precipitation at the bottom of the container, or both were observed.

[Solvent shock]
After adding 9 times the mass of butyl acetate or 9 times the mass of γ-butyrolactone to the mass of the metal oxide dispersion and leaving it to stand at room temperature for one week, the dispersion was carefully visually observed and evaluated according to the following criteria. evaluated. The results are shown in Table 2 or 3.
+ (Good): Neither cloudiness of the entire dispersion nor precipitation at the bottom of the container was observed.
- (Poor): White turbidity of the entire dispersion, precipitation at the bottom of the container, or both were observed.

As can be seen from Tables 2 and 3, the metal oxide dispersions of Examples have excellent stability over time and the occurrence of solvent shock is suppressed, whereas the metal oxide dispersions of Comparative Examples have It was confirmed that the stability over time, the effect of suppressing the occurrence of solvent shock, or both were poor.

Claims (6)

Aromatic carboxylic acids having aromatic rings substituted with alkyl groups, aromatic carboxylic acids having aromatic rings substituted with alkoxy groups, aromatic carboxylic acids having aromatic rings substituted with alkoxycarbonyl groups, and acyloxy groups. a first carboxylic acid that is at least one aromatic carboxylic acid selected from the group consisting of aromatic carboxylic acids having a substituted aromatic ring;
metal oxide nanoparticles surface-treated with a capping agent;
solvent and
A metal oxide dispersion containing,
The capping agent includes a second carboxylic acid having an ester bond and a polymerizable double bond,
The second carboxylic acid is a metal oxide dispersion liquid different from the first carboxylic acid. The metal oxide according to claim 1, wherein the first carboxylic acid is present in the metal oxide dispersion separately from the metal oxide nanoparticles and/or in the capping agent. material dispersion. The metal oxide dispersion according to claim 1 or 2, wherein the second carboxylic acid has an aromatic ring. The ratio of the mass of the first carboxylic acid present in the metal oxide dispersion separately from the metal oxide nanoparticles to the mass of the solid content of the metal oxide dispersion is 10 The metal oxide dispersion according to claim 1 or 2, wherein the metal oxide dispersion is at most % by mass. The metal oxide dispersion according to claim 1 or 2, wherein in the solid content of the metal oxide dispersion, the ratio of the inorganic content to the total of the inorganic content and the organic content is 25% by mass or more. The metals contained in the metal oxide nanoparticles include zinc, yttrium, hafnium, zirconium, lanthanum, cerium, neodymium, gadolinium, holmium, lutetium, tantalum, titanium, silicon, aluminum, antimony, tin, indium, tungsten, copper, The metal oxide dispersion according to claim 1 or 2, which is at least one selected from the group consisting of vanadium, chromium, niobium, molybdenum, ruthenium, rhodium, rhenium, iridium, germanium, gallium, thallium, and magnesium.