Dispersion of surface-treated silica-containing inorganic oxide particles and method for producing the same

Abstract

To provide a dispersion of inorganic oxide particles having high dispersion stability under high temperature and high salinity.SOLUTION: A dispersion comprises silane-bound inorganic oxide particles surface-modified with hydrolyzable silane as a dispersion and a liquid medium as a dispersion medium, and the dispersion medium comprises a hydrolyzate of the hydrolyzable silane. The ratio of (number of moles of silicon atoms in the hydrolyzate of hydrolyzable silane in the dispersion medium) / (number of moles of silicon atoms of silane bonded to the surface of the inorganic oxide particles) is 0.2 to 30. Q4, where the number of bridging oxygen between silicon atoms of the silica particles is 4 / 2 per one silicon atom in Si-NMR observation, is increased compared to the state before the silane surface modification. The inorganic oxide is at least one kind of inorganic oxide selected from the group consisting of silica, alumina, tin oxide, zirconium oxide, titanium oxide, and antimony oxide having an average particle diameter of 5 nm to 100 nm. Also provided are a single metal oxide and a complex metal oxide or a complex oxide having a core-shell structure.SELECTED DRAWING: None

Description

[Technical Field] 【0001】 This invention relates to dispersions of silane-bonded silica-containing inorganic oxide particles whose surfaces have been treated with silane, and to methods for producing the same. Hereinafter, "silane-bonded silica-containing inorganic oxide particles" may also be referred to as "silica-containing inorganic oxide particles." [Background technology] 【0002】 Dispersions of silica-containing inorganic oxide particles, particularly silica sols, are liquids in which silica particles are dispersed in a dispersion medium. One method for highly dispersing silica particles is to increase the absolute value of the zeta potential between silica particles to enhance the repulsive force between them. One such method involves modifying the surface of the silica particles with a silane coupling agent having cationic or anionic functional groups when the dispersion medium is an aqueous solution, or modifying the surface of the silica particles with a silane coupling agent having hydrophobic organic groups when the dispersion medium is an organic solvent. For example, a method for producing an organic solvent-dispersed silica sol is disclosed, which includes the steps of surface treatment by adding a silicon alkoxide having two or more alkoxide groups bonded to silicon atoms, or a silicon alkoxide having one or more hydroxyl groups bonded to silicon atoms and one or more alkoxide groups bonded to silicon atoms, to a hydrophilic inorganic oxide sol, and replacing the dispersion medium with a non-alcoholic organic solvent in the presence of a primary alcohol having 3 to 12 carbon atoms (see Patent Document 1). A dispersion of surface-treated particles is disclosed, comprising surface-treated particles in which a primary organosilicon compound is bonded to the surface of metal oxide particles with a refractive index of 1.65 or higher, a secondary organosilicon compound not bonded to the metal oxide particles, and an organic solvent, wherein the ratio of (primary organosilicon compound) to (secondary organosilicon compound) is 0.1 to 9.0 (see Patent Document 2). [Prior art documents] [Patent Documents] 【0003】 [Patent Document 1] Japanese Patent Publication No. 2005-200294 [Patent Document 2] Japanese Patent Publication No. 2020-164374 [Overview of the Initiative] [Problems that the invention aims to solve] 【0004】 The present invention provides a dispersion of silica-containing inorganic oxide particles, particularly a dispersion of silica particles, that exhibits high dispersion stability even under high temperature and high salinity conditions. [Means for solving the problem] 【0005】 The present invention, in its first aspect, provides a dispersion comprising a liquid medium as the dispersion medium, wherein the dispersion medium contains silane-bonded silica-containing inorganic oxide particles surface-modified with hydrolyzable silane as the dispersed phase, the dispersion medium containing the hydrolysate of the hydrolyzable silane, the ratio of (number of moles of silicon atoms in the hydrolysate of the hydrolyzable silane in the dispersion medium) / (number of moles of silicon atoms of silane bonded to the surface of the inorganic oxide particles) is 0.2 to 30, and the Q4, where the number of bridging oxygen atoms between silicon atoms of the silica particles is 4 / 2 per silicon atom, is increased by Si-NMR observation compared to before the silane surface modification. From a second perspective, the silica-containing inorganic oxide particles are silica particles with an average particle diameter of 5 nm to 100 nm, or at least one inorganic oxide particle selected from the group consisting of silica and alumina, tin oxide, zirconium oxide, titanium oxide, and antimony oxide, wherein the silica-containing inorganic oxide particles are silica particles, a composite metal oxide of silica and other metal oxides, or The dispersion according to the first aspect, which is a composite oxide particle having a core-shell structure of lichen and other metal oxides, From a third perspective, hydrolyzable silanes are given by formulas (1) to (3): [ka] (In formula (1), R 3is an organic group having an alkyl group, a halogenated alkyl group, an alkenyl group, or an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, or a cyano group and bonded to a silicon atom by a Si-C bond, R 4 represents an alkoxy group, an acyloxy group, or a halogen group, a represents an integer of 1 to 3, In formula (2) and formula (3), R 5 and R 7 are alkyl groups having 1 to 3 carbon atoms and bonded to a silicon atom by a Si-C bond, R 6 and R 8 represent an alkoxy group, an acyloxy group, or a halogen group, Y represents an alkylene group, an NH group, or an oxygen atom, and the R 5 and R 7 at least one of which is an alkyl group having 1 to 3 carbon atoms and bonded to a silicon atom by a Si-C bond, b is an integer of 1 to 3, c is an integer of 0 or 1, d is an integer of 1 to 3, and e is an integer of 1 to 3.) The dispersion according to the first aspect or the second aspect, which is at least one silane compound selected from the group consisting of As a fourth aspect, in the hydrolyzate of the hydrolyzable silane in the dispersion medium, for the hydrolyzate of the silane compound in which a in formula (1) is an integer of 1, regarding the T0, T1, T2, and T3 structures in which the ratio of the crosslinked oxygen between silicon atoms shows 0 / 2, 1 / 2, 2 / 2, and 3 / 2 per silicon atom, (T2 + T3) / (T0 + T1) is a specific value (2 to 15), or the (T1 + T2 + T3) / (T0) ratio is a specific value (5 to 100), the dispersion according to the third aspect containing a silane compound As a fifth aspect, in the hydrolyzate of the hydrolyzable silane in the dispersion medium, for the hydrolyzate of the silane compound in which a in formula (1) is an integer of 2, regarding the D0, D1, and D2 structures in which the ratio of the crosslinked oxygen between silicon atoms shows 0 / 2, 1 / 2, and 2 / 2 per silicon atom, the (D1 + D2) / (D0) ratio is 0.1 to 10, or the (D2) / (D0 + D1) ratio is 0.01 to 10, the dispersion according to the third aspect containing a silane compound As a sixth aspect, a value obtained by dividing the amount of water vapor adsorbed by the silica-containing inorganic oxide particles by the amount of nitrogen gas adsorbed, i.e., (specific surface area calculated from the amount of water vapor adsorbed) / (specific surface area calculated from the amount of nitrogen gas adsorbed), is 0.15 to 0.95 as compared to the silica-containing inorganic oxide particles before the addition of the silane compound, and the dispersion according to any one of the first to fifth aspects. As a seventh aspect, the following steps (A) to (B): (A) step: a step of obtaining an aqueous dispersion of the silica-containing inorganic oxide particles; (B) step: adding a hydrolyzable silane at a pH of 2.0 to 6.5 to the aqueous dispersion of the silica-containing inorganic oxide particles in a ratio of the number of the silanes per unit surface area of the particles in the range of 0.3 to 100 per nm 2 and heating the mixture to a temperature within 50 to 99 °C after stirring at room temperature, and performing the stirring after heating for a time within 1 to 7 times the stirring time at room temperature. The method for producing a dispersion according to any one of the first to sixth aspects, and As an eighth aspect, after the step (B), a further step (C): (C) step: a step of replacing the aqueous medium of the dispersion obtained in the step (B) with an organic solvent. The method for producing a dispersion using an organic solvent as a dispersion medium according to the seventh aspect. 【Advantages of the Invention】 【0006】 In a silica-containing inorganic oxide particle, particularly an inorganic particle dispersion such as silica, the dispersion stability is ensured by the repulsive force between the particles. For example, taking silica particles as an example, silanol groups exist on the surface of silica particles, and repulsion between the particles occurs due to the negative charges of the silanol groups. The absolute value of the charge changes due to the influence of pH and salts in the dispersion. There are surface-treated particles that are less affected by pH and salts. For example, in the case of silica particles, methods of surface-treating with a hydrolyzable silane compound having a cationic functional group having a positive charge on the silica particle surface or a hydrolyzable silane compound having an anionic functional group having a negative charge are exemplified. These have repulsive forces between the particles due to the electrical repulsion between the cationic and anionic functional groups, respectively. 【0007】 Depending on the density of the functional groups bonded to the surface of the silica particles, it is difficult to modify the entire particle surface with these functional groups, and the repulsive force between particles is not necessarily sufficient under pH and salt concentration conditions. Incidentally, when a silane compound with a functional group is added to a dispersion of silica particles, there are two types: silanes with a functional group attached to the surface of the silica particles (bound silanes) and silanes with a functional group that is dissolved in the dispersion medium without being attached to the silica particles (hereinafter referred to as free silanes). The silanes with a functional group in the dispersion medium are present between the silica particles, and because they have the same functional group, repulsive forces are generated between the bound silanes and the free silanes. As a result, repulsive forces occur not only between the silica particles but also between the silane monomers, resulting in a dispersion with high dispersion stability. 【0008】 In this invention, it was found that a specific ratio (0.2 to 30) between (the number of moles of silicon atoms in the hydrolyzable silane hydrolysate in the dispersion medium) and (the number of moles of silicon atoms of silane bonded to the surface of inorganic oxide particles) yields a dispersion of silica particles with high dispersion stability. Furthermore, when the dispersion medium is an organic solvent, silica particles have hydrophilicity based on silanols, which differs from the properties of the organic solvent. Therefore, the silanol groups of the silica particles are surface-treated with silanes having hydrophobic functional groups to make them highly compatible with organic solvents. Since it is difficult to modify the entire particle with the hydrophobic functional group of the silane, compatibility can be ensured with a silane monomer having hydrophobic functional groups in the parts of the silica particles that are not modified with the hydrophobic functional group, thereby creating a dispersion that is highly dispersible in organic solvents. 【0009】 In the present invention, it is preferable that the hydrolyzable silane hydrolysates in the dispersion medium exist in a delocalized state throughout the dispersion medium due to the repulsive force between silica particles and silane monomers. For this reason, it is preferable that the polymerization of free silane does not proceed excessively. For example, when using a silane with three hydrolysis groups, it is preferable that the hydrolyzable silane compounds of the silane compound have T0, T1, T2, and T3 structures where the ratio of bridging oxygen between silicon atoms is 0 / 2, 1 / 2, 2 / 2, and 3 / 2 per silicon atom as observed by Si-NMR, and that (T2+T3) / (T0+T1) is a specific value (2 to 15, preferably 2 to 10), or that the (T1+T2+T3) / (T0) ratio is a specific value (5 to 100, preferably 5 to 50). It is acceptable to satisfy either one of these conditions, but it is more preferable to satisfy both. Furthermore, when using a silane with two hydrolysis groups, it is preferable that the hydrolyzed silane compounds have D0, D1, and D2 structures where the ratio of bridging oxygen between silicon atoms is 0 / 2, 1 / 2, and 2 / 2 per silicon atom as observed by Si-NMR, and that the (D1+D2) / (D0) ratio is a specific value (0.1~10) or the (D2) / (D0+D1) ratio is a specific value (0.01~10). Satisfying either one of these is acceptable, but satisfying both is more preferable. 【0010】 For silica-containing inorganic oxide particles, especially silica particles, by setting the ratio of the amount of water vapor adsorbed to the silica particles to the amount of nitrogen gas adsorbed (specific surface area calculated from water vapor adsorption) / (specific surface area calculated from nitrogen gas adsorption) to a range of 0.15 to 0.95 compared to silica particles before the addition of the silane compound, the inorganic oxide particles can be made highly compatible with a wide range of media, from aqueous to organic solvents. Silica particles that satisfy these bonded silane and free silane requirements show an increase in Q4 (where the bridging oxygen between silicon atoms in the silica particle is 4 / 2 per silicon atom) compared to before the silane surface modification, as observed by Si-NMR. For example, the increase ratio can be in the range of 1.01 to 1.5, or 1.01 to 1.15. [Modes for carrying out the invention] 【0011】 The present invention relates to a dispersion comprising silane-bonded silica-containing inorganic oxide particles surface-modified with hydrolyzable silane as a dispersed phase, wherein the dispersion medium contains hydrolysates of the hydrolyzable silane, and the ratio of (number of moles of silicon atoms in the hydrolysates of the hydrolyzable silane in the dispersion medium) / (number of moles of silicon atoms of silane bonded to the surface of the inorganic oxide particles) is 0.2 to 30, preferably 0.2 to 15, and the Q4, where the number of bridging oxygen atoms between silicon atoms of the silica particles is 4 / 2 per silicon atom, is increased compared to before the surface modification of the silane, as observed by Si-NMR. 【0012】 In this invention, unless otherwise specified, the average particle diameter of an inorganic substance, such as aqueous silica sol (colloidal silica particles), refers to the specific surface area diameter obtained by measurement using the nitrogen adsorption method (BET method). The specific surface area diameter (average particle diameter (specific surface area diameter) D (nm)) obtained by measurement using the nitrogen adsorption method (BET method) is the specific surface area S (m²) measured by the nitrogen adsorption method. 2 From / g), D(nm) is given by the formula D(nm) = 2720 / S. The silica-containing inorganic oxide particles are silica particles with an average particle diameter of 5 nm to 100 nm, preferably 5 to 60 nm, as measured by the BET method, or at least one inorganic oxide particle selected from the group consisting of silica and alumina, tin oxide, zirconium oxide, titanium oxide, and antimony oxide. The silica-containing inorganic oxide particles include silica particles, composite metal oxides of silica and other metal oxides, or composite oxide particles having a core-shell structure of silica and other metal oxides. For example, silica particles are preferably used as the single metal oxide, and examples of composite metal oxides include composite metal oxide particles of silica and alumina, and composite metal oxide particles of tin oxide and silica. Examples of composite oxide particles having a core-shell structure include titanium oxide, or composite oxide particles with a core structure of titanium oxide and zirconium oxide, and a shell of tin oxide and silica. 【0013】 In the present invention, the silica-containing inorganic oxide particles are obtained in a dispersion medium as a dispersion liquid with a concentration of, for example, 1 to 50% by mass. The dispersion of the present invention is prepared by the following steps (A) to (B): (A) Step: A step to obtain an aqueous dispersion of the above silica-containing inorganic oxide particles, (B) Step: Add hydrolyzable silane to the aqueous dispersion of the silica-containing inorganic oxide particles at a pH of 2.0 to 6.5, with a ratio of 0.3 to 100 silane particles per particle surface area at 0.3 to 100 particles / nm. 2 The method includes adding an additive within a certain range, stirring at room temperature, then raising the temperature to 50-99°C, and performing the stirring after the temperature increase for a duration of 1 to 7 times longer than the stirring time at room temperature. (A) The aqueous dispersion of silica-containing inorganic oxide particles obtained in step (A) is obtained as a dispersion of silica-containing inorganic oxide particles in an aqueous medium at a concentration of, for example, 1 to 50% by mass. For example, taking aqueous silica sol as an example, aqueous silica sol is made using water glass as a starting material and consists of a) a step of obtaining activated silicic acid by cation exchange of water glass, and b) a step of obtaining silica particles by heating the activated silicic acid. In step a), mineral acid (for example, hydrochloric acid, nitric acid, or sulfuric acid) is added to purify the activated silicic acid, and metal impurities other than silica are eluted by cation exchange and anion exchange to obtain gold Activated silica, from which impurities and unwanted anions have been removed, can be used. In step b), an alkaline component (e.g., NaOH, KOH) is added to the activated silica to promote the growth of silica particles. To accelerate the growth of silica particles, a seed solution and a feed solution are prepared by adding alkali to the activated silica obtained in step a), and by supplying the feed solution while heating the seed solution, the silica particle diameter is increased to obtain an aqueous silica sol with a desired particle size. In step (B), the pH of the aqueous dispersion of silica-containing inorganic oxide particles obtained in step (A) can be adjusted to 2.0 to 6.5, and hydrolyzable silane can be added. Acids or alkalis can be used to adjust the pH. 【0014】 Examples of acids include mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as formic acid, oxalic acid, citric acid, acetic acid, lactic acid, malic acid, succinic acid, tartaric acid, butyric acid, fumaric acid, propionic acid, and ascorbic acid. Examples of alkalis include ammonia, amines, quaternary ammonium hydroxides, alkali metal hydroxides, alkali metal alkoxides, and alkali metal salts of aliphatic carboxylic acids. Examples of amines include primary amines, secondary amines, and tertiary amines. Examples of primary amines include methylamine, ethylamine, n-propylamine, and i-propylamine. Examples of secondary amines include ethyl n-propylamine, ethyl i-propylamine, dipropylamine, di-i-propylamine, ethyl butylamine, n-propylbutylamine, dibutylamine, ethyl pentylamine, n-propylpentylamine, i-propylpentylamine, dipentylamine, ethyl octylamine, i-propyloctylamine, butyl octylamine, and dioctylamine. Examples of the above-mentioned tertiary amines include triethylamine, ethyl di-npropylamine, diethyl-npropylamine, tri-npropylamine, tri-ipropylamine, ethyl dibutylamine, diethylbutylamine, i-propyl dibutylamine, di-ipropylbutylamine, tributylamine, ethyl dipentylamine, diethylpentylamine, tripentylamine, methyl dioctylamine, dimethyl octylamine, ethyl dioctylamine, diethyl octylamine, and trioctylamine. As the quaternary ammonium hydroxide, tetraalkylammonium hydroxide with a total number of carbon atoms of 4 to 40 is preferred. Examples include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetran-propylammonium hydroxide, tetrai-propylammonium hydroxide, tetrabutylammonium hydroxide, and ethyltrimethylammonium hydroxide. Examples of alkali metal hydroxides include sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate. Examples of alkali metal alkoxides include sodium methoxide, sodium ethoxide, potassium methoxide, and potassium ethoxide. Examples of alkali metal salts of aliphatic carboxylic acids include saturated alkali metal salts and unsaturated alkali metal salts of aliphatic carboxylic acids having 10 to 30 carbon atoms. Examples of alkali metals include sodium and potassium. Examples of saturated alkali metal salts of aliphatic carboxylic acids include alkali metal salts of laurate, alkali metal salts of myristate, alkali metal salts of palmitate, and alkali metal salts of stearate. Examples of alkali metal salts of unsaturated aliphatic carboxylic acids include alkali metal salts of oleate, alkali metal salts of linoleate, and alkali metal salts of linolenate. 【0015】 (B) As the hydrolyzable silane used in step (B), at least one silane compound selected from the group consisting of formulas (1) to (3) above can be used. In formula (1), R 3 This includes alkyl groups, halogenated alkyl groups, alkenyl groups, or epoxy groups, (meth)acryloyl groups, mercapto groups, amino groups, ureido groups, or cyano groups. An organic group having a silicon atom bonded by a Si-C bond, R 4 represents an alkoxy group, an acyloxy group, or a halogen group, and a represents an integer from 1 to 3. In equations (2) and (3), R 5 and R 7 R is an alkyl group having 1 to 3 carbon atoms and bonded to a silicon atom by a Si-C bond. 6 and R 8 represents an alkoxy group, an acyloxy group, or a halogen group, Y represents an alkylene group, an NH group, or an oxygen atom, and R represents an alkylene group, an NH group, or an oxygen atom. 5 and R 7 is an alkyl group having at least one carbon atom between 1 and 3 carbon atoms, bonded to a silicon atom by a Si-C bond; b is an integer between 1 and 3; c is an integer between 0 and 1; d is an integer between 1 and 3; and e is an integer between 1 and 3. 【0016】The alkyl groups mentioned above are alkyl groups having 1 to 18 carbon atoms, for example, methyl group, ethyl group, n-propyl group, i-propyl group, cyclopropyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, cyclobutyl group, 1-methyl-cyclopropyl group, 2-methyl-cyclopropyl group, n-pentyl group, 1-methyl-n-butyl group, 2-methyl-n-butyl group, 3-methyl-n-butyl group, 1,1-dimethyl-n-propyl group, 1,2-dimethyl-n-propyl group, 2,2-dimethyl-n-propyl group, 1-ethyl- n-propyl group, cyclopentyl group, 1-methyl-cyclobutyl group, 2-methyl-cyclobutyl group, 3-methyl-cyclobutyl group, 1,2-dimethyl-cyclopropyl group, 2,3-dimethyl-cyclopropyl group, 1-ethyl-cyclopropyl group, 2-ethyl-cyclopropyl group, n-hexyl group, 1-methyl-n-pentyl group, 2-methyl-n-pentyl group, 3-methyl-n-pentyl group, 4-methyl-n-pentyl group, 1,1-dimethyl-n-butyl group, 1,2-dimethyl-n-butyl group, 1,3-dimethyl-n-butyl group , 2,2-dimethyl-n-butyl group, 2,3-dimethyl-n-butyl group, 3,3-dimethyl-n-butyl group, 1-ethyl-n-butyl group, 2-ethyl-n-butyl group, 1,1,2-trimethyl-n-propyl group, 1,2,2-trimethyl-n-propyl group, 1-ethyl-1-methyl-n-propyl group, 1-ethyl-2-methyl-n-propyl group, cyclohexyl group, 1-methyl-cyclopentyl group, 2-methyl-cyclopentyl group, 3-methyl-cyclopentyl group, 1-ethyl-cyclobutyl group, 2-ethyl-cyclobutyl Group, 3-ethyl-cyclobutyl group, 1,2-dimethyl-cyclobutyl group, 1,3-dimethyl-cyclobutyl group, 2,2-dimethyl-cyclobutyl group, 2,3-dimethyl-cyclobutyl group, 2,4-dimethyl-cyclobutyl group, 3,3-dimethyl-cyclobutyl group, 1-n-propyl-cyclopropyl group, 2-n-propyl-cyclopropyl group, 1-i-propyl-cyclopropyl group, 2-i-propyl-cyclopropyl group, 1,2,2-trimethyl-cyclopropyl group, 1,2,3-trimethyl-cyclopropyl group, 2,2,Examples of such groups include, but are not limited to, 3-trimethylcyclopropyl group, 1-ethyl-2-methylcyclopropyl group, 2-ethyl-1-methylcyclopropyl group, 2-ethyl-2-methylcyclopropyl group and 2-ethyl-3-methylcyclopropyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, etc. Furthermore, alkylene groups can be derived from the alkyl groups mentioned above. 【0017】 Alkenyl groups are alkenyl groups having 2 to 10 carbon atoms, including ethenyl group, 1-propenyl group, 2-propenyl group, 1-methyl-1-ethenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-ethylethenyl group, 1-methyl-1-propenyl group, 1-methyl-2-propenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 1-n-propylethenyl group, 1-methyl-1-butenyl group, 1-methyl-2-butenyl group, 1-methyl-3-butenyl group, 2-ethyl-2-propenyl group, 2-methyl-1-butenyl group, 2-methyl-2-butenyl group, 2-methyl-3-butenyl group, 3-methyl-1-butenyl group, 3-methyl-2-butenyl group, 3-methyl-3-butenyl group, 1,1-dimethyl Examples of such groups include, but are not limited to, 2-propenyl group, 1-i-propylethenyl group, 1,2-dimethyl-1-propenyl group, 1,2-dimethyl-2-propenyl group, 1-cyclopentenyl group, 2-cyclopentenyl group, 3-cyclopentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, 5-hexenyl group, 1-methyl-1-pentenyl group, 1-methyl-2-pentenyl group, 1-methyl-3-pentenyl group, 1-methyl-4-pentenyl group, 1-n-butylethenyl group, 2-methyl-1-pentenyl group, and 2-methyl-2-pentenyl group. 【0018】 The alkoxy groups mentioned above include, but are not limited to, alkoxy groups having 1 to 10 carbon atoms, such as methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group, s-butoxy group, t-butoxy group, n-pentyloxy group, 1-methyl-n-butoxy group, 2-methyl-n-butoxy group, 3-methyl-n-butoxy group, 1,1-dimethyl-n-propoxy group, 1,2-dimethyl-n-propoxy group, 2,2-dimethyl-n-propoxy group, 1-ethyl-n-propoxy group, and n-hexyloxy group. 【0019】 The above-mentioned acyloxy groups, which have 2 to 10 carbon atoms, include, but are not limited to, methyl carbonyloxy group, ethyl carbonyloxy group, n-propyl carbonyloxy group, i-propyl carbonyloxy group, n-butyl carbonyloxy group, i-butyl carbonyloxy group, s-butyl carbonyloxy group, t-butyl carbonyloxy group, n-pentyl carbonyloxy group, 1-methyl-n-butyl carbonyloxy group, 2-methyl-n-butyl carbonyloxy group, 3-methyl-n-butyl carbonyloxy group, 1,1-dimethyl-n-propyl carbonyloxy group, 1,2-dimethyl-n-propyl carbonyloxy group, 2,2-dimethyl-n-propyl carbonyloxy group, 1-ethyl-n-propyl carbonyloxy group, n-hexyl carbonyloxy group, 1-methyl-n-pentyl carbonyloxy group, and 2-methyl-n-pentyl carbonyloxy group. Examples of the halogen groups mentioned above include fluorine, chlorine, bromine, and iodine. The above term "(meth)acryloyl group" refers to both an acryloyl group and a methacryloyl group. Formulas (2) and (3) above are preferably compounds that can form a trimethylsilyl group on the surface of silica particles. Examples of such compounds are listed below. [ka] In the above formula, R 12The group is an alkoxy group, such as a methoxy group or an ethoxy group. A hydroxyl group, for example a silanol group in the case of silica particles, reacts with the silane compound on the surface of the silica particles, and the silane compound coats the surface of the silica particles via siloxane bonds. This is the process. 【0020】 The reaction temperature can be anywhere from 20°C to the boiling point of the dispersion medium, for example, between 20°C and 100°C. The reaction time is approximately 0.1 to 6 hours. 【0021】 Preferred functional groups include amino groups, epoxy groups, alkyl groups, and phenyl groups, such as aminopropyl groups, aminoethylaminopropyl groups, methyl groups, phenyl groups, glycidoxypropyl groups, epoxycyclohexylethyl groups, and trifluoropropyl groups. Corresponding silane compounds include aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminoethylaminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, aminoethylaminopropylmethyldiethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, glycidoxypropyltrimethoxysilane, glycidoxypropyltriethoxysilane, epoxycyclohexylethyltrimethoxysilane, epoxycyclohexylethyltriethoxysilane, trifluoropropyltrimethoxysilane, and trifluoropropyltriethoxysilane. 【0022】 The above silane compound is defined as having a coating amount on the silica particle surface, with a silicon atom count of 0.1 atoms / nm in the silane compound. 2 ~4.0 pieces / nm 2 The silica particle surface can be coated by adding a silane compound equivalent to the coating amount to the silica sol. Water is required for the hydrolysis of the above silane compounds, and if an aqueous solvent sol is used, then those aqueous solvents can be used. Furthermore, hydrolysis can be carried out with or without a catalyst. When performed without a catalyst, the surface of the silica particles acts as a catalyst, and silica sols with a pH of 2.0 to 6.5 can be used. 【0023】 When a catalyst is used, examples of hydrolysis catalysts include metal chelate compounds, organic acids, inorganic acids, organic bases, and inorganic bases. Examples of metal chelate compounds used as hydrolysis catalysts include triethoxy mono(acetylacetonate) titanium and triethoxy mono(acetylacetonate) zirconium. Examples of organic acids used as hydrolysis catalysts include acetic acid and oxalic acid. Examples of inorganic acids used as hydrolysis catalysts include hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, and phosphoric acid. Examples of organic bases used as hydrolysis catalysts include pyridine, pyrrole, piperazine, and quaternary ammonium salts. Examples of inorganic bases used as hydrolysis catalysts include ammonia, sodium hydroxide, and potassium hydroxide. 【0024】 In step (B) above, hydrolyzable silane is added to the aqueous dispersion of inorganic oxide particles obtained in step (A). It is preferable that the stirring time after heating to 50-99°C is 1 to 100 times, or 1 to 7 times, compared to the stirring time at room temperature. If the ratio is 1 to 100 times, or 1 to 7 times, sufficient coating of the hydrolyzable silane hydrolysate with the inorganic oxide particles (e.g., silica particles) does not occur, and the silane compound present in the dispersion medium is later locally coated, making it impossible to achieve uniform coating. If the ratio is 7 times or more, the proportion of T1, T2, T3, D1, and D2 structures decreases, which is undesirable in terms of particle repulsion. 【0025】 In this invention, both a state in which hydrolyzable silane hydrolysates are bound to silica particles and a state in which hydrolyzable silane hydrolysates exist in the dispersion medium coexist. The ratio of silicon atoms (moles) in the silane is between 0.2 and 30, which contributes to the stability of the inorganic oxide sol (silica sol). 【0026】 In the state in which the hydrolyzable silane hydrolysate of the present invention is bonded to silica particles, the amount of silanol in the silica particles decreases, and this is characterized by an increase in Q4, where the bridging oxygen between silicon atoms in the silica particles is 4 / 2 per silicon atom, as observed by Si-NMR, compared to before the surface modification of the silane. 【0027】 Furthermore, when hydrolyzable silane hydrolysates are bound to silica particles, the specific surface area of ​​the silica particles, calculated by dividing the specific surface area calculated from the amount of water vapor adsorbed by the amount of nitrogen gas adsorbed, is between 0.15 and 0.95 compared to the silica particles before the addition of the silane compound. 【0028】 This value indicates that the surface of the silica particles has been replaced from silanol groups to silane compounds containing functional groups. Furthermore, the hydrolyzable silane hydrolysates in the dispersion medium are characterized by containing silane compounds in which the hydrolyzable silane compounds in formula (1) where a is an integer of 1 show, as observed by Si-NMR, that the ratio of bridging oxygen between silicon atoms is 0 / 2, 1 / 2, 2 / 2, and 3 / 2 per silicon atom in T0, T1, T2, and T3 structures, and the (T2+T3) / (T0+T1) ratio is 2 to 10 or the (T1+T2+T3) / (T0) ratio is 5 to 100. While either of these conditions may be met, it is more preferable to satisfy both. Furthermore, the hydrolyzable silane hydrolysates in the dispersion medium are characterized by containing silane compounds in which the hydrolyzable silane compounds in formula (1) where a is an integer of 2 have a (D1+D2) / (D0) ratio of 0.1 to 10, or a (D2) / (D0+D1) ratio of 0.01 to 10, for D0, D1, and D2 structures where the ratio of bridging oxygen between silicon atoms is 0 / 2, 1 / 2, and 2 / 2 per silicon atom as observed by Si-NMR. Satisfying either one of these conditions is acceptable, but satisfying both is more preferable. 【0029】 The dispersion of the present invention thus obtained is further processed in step (C) after step (B): (C) Step: A step of replacing the aqueous medium of the dispersion obtained in step (B) with an organic solvent, thereby obtaining a dispersion with an organic solvent as the dispersion medium. 【0030】 Organic solvents include alcohols, ketones, ethers, esters, amides, and hydrocarbons. Alcohols are those with 1 to 10 carbon atoms, such as methanol, ethanol, i-propanol, n-propanol, and butanol. Ketones are linear or cyclic aliphatic ketones with 3 to 30 carbon atoms, such as methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, diisobutyl ketone, methyl amyl ketone, and cyclohexanone. Ethers are linear or cyclic aliphatic ethers with 3 to 30 carbon atoms, such as diethyl ether and tetrahydrofuran. Esters are linear or cyclic esters having 2 to 30 carbon atoms, such as ethyl acetate, butyl acetate, sec-butyl acetate, methoxybutyl acetate, amyl acetate, n-propyl acetate, i-propyl acetate, ethyl lactate, butyl lactate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, phenyl acetate, phenyl lactate, and phenyl propionate. Amides are aliphatic amides having 3 to 30 carbon atoms, such as dimethylacetamide, dimethylformamide, N-methylpyrrolidone, and N-ethylpyrrolidone. Hydrocarbons are linear or cyclic aliphatic or aromatic hydrocarbons having 6 to 30 carbon atoms. These are hydrogen compounds, such as hexane, heptane, octane, nonane, decane, benzene, toluene, and xylene. 【0031】 The silica-containing inorganic oxide sol (e.g., silica sol) of the present invention can be used in high-salt dispersion media sols, adhesives, mold release agents, semiconductor encapsulants, LED encapsulants, paints, film additives, hard coat agents, photoresist materials, printing inks, cleaning agents, cleaners, additives for various resins, insulating compositions, rust inhibitors, lubricants, metalworking oils, film coatings, release agents, well treatment agents, and the like. [Examples] 【0032】 (Measuring device) The analysis of aqueous silica sol (pH value, electrical conductivity, viscosity, DLS average particle size, silane bond content), and the analysis of samples prepared using the aqueous silica sol after room temperature salt resistance testing or high-temperature salt resistance testing, were performed using the following apparatus. • DLS average particle diameter (average particle diameter by dynamic light scattering): A dynamic light scattering particle diameter measuring device, Zetasizer Nano (manufactured by Malvern Division, Spectris Corporation), was used. • pH: A pH meter (manufactured by Toa DKK Co., Ltd.) was used. • Electrical conductivity: An electrical conductivity meter (manufactured by Toa DKK Co., Ltd.) was used. Viscosity: A BMII type viscometer (manufactured by Tokyo Keiki Co., Ltd.) was used. • Silane bond content: Analyzed using either a CHNS / O analyzer (PerkinElmer Japan Co., Ltd.) or a TN-2100V Total Nitrogen Analyzer (Mitsubishi Chemical Analytec Co., Ltd.). • Si-NMR: AVANCED NEO (manufactured by Bruker, Inc.) was used. • Nitrogen gas adsorption capacity: MONOSORB (manufactured by Quantachrome INSTRUMENTS) was used. • Water vapor adsorption amount: A Q5000SA adsorption analyzer (manufactured by T.A. Instruments Japan Co., Ltd.) was used. 【0033】 [Evaluation of silica sol] (Removal of silanes not bound to silica particles (free silanes)) Two grams of aqueous silica sol and four grams of pure water were placed in a 15 ml centrifugal filter unit, product name Amicon Ultra-15 (Merck KGaA), and centrifuged at 2770 G for 20 minutes. After centrifugation, the liquid discharged to the bottom of the unit was discarded, and an equal mass of pure water was added to the concentrated aqueous silica sol on the filter to redisperse it. The mixture was then centrifuged again at 2770 G for 20 minutes. The above procedure was repeated a total of four times to obtain aqueous silica sol from which free silanes had been removed. 【0034】 (Measurement of carbon content) Aqueous silica sol from which free silanes had been removed was heated and dried at 100°C, and then ground in a mortar to obtain silica sol powder. The carbon content of the obtained silica sol powder was measured using an organic trace element metal analyzer, and the amount of silane bond was calculated from the obtained carbon content using the following formula. Surface treatment amount = (Cm ÷ Cn ÷ Sc × A) / (Ct × Cs) However, Cm is the carbon content, Cn is the carbon molecular weight, Sc is the number of carbon atoms in the silane, A is Avogadro's number, Ct is the silica particle mass, and Cs is the silica specific surface area. The unit of the silane bond amount obtained from the carbon content measurement is (bonds / nm) 2 ) 【0035】 (Measurement of nitrogen content) The nitrogen content of the aqueous silica sol from which free silanes had been removed was measured using a TN measuring device, and the amount of silane bonded was calculated from the obtained nitrogen content using the following formula. Surface treatment amount = (Nm ÷ Nn ÷ Sn × A) / (Ct × Cs) However, Nm is nitrogen content, Nn is nitrogen molecular weight, Sn is the number of nitrogen atoms in silane, A is Avogadro's number, Ct is silica particle mass, and Cs is silica specific surface area. The unit of the silane bond amount obtained from the nitrogen content measurement is (bonds / nm). 2 ) 【0036】 (Measurement of water vapor adsorption) The aqueous silica sol obtained by removing the free silane described above was dried on an 80°C hot plate to obtain silica gel. The resulting silica gel was then crushed in a mortar and pestle, and further dried at 150°C for 3 hours to obtain silica dry powder. Based on the BET theory, the specific surface area (m²) of this powder was determined by water vapor adsorption. 2 The concentration ( / g) was measured (steam BET method). 【0037】 (Measurement of nitrogen gas adsorption) The aqueous silica sol obtained by removing the free silane as described above was dried on an 80°C hot plate, and the resulting silica gel was crushed in a mortar and pestle. Further drying at 150°C for 3 hours yielded a silica-dried powder. Based on the BET theory, the specific surface area (m²) of this powder was determined by nitrogen adsorption. 2The concentration ( / g) was measured (BET method, i.e., nitrogen gas BET method). 【0038】 (Salt tolerance evaluation) (Preparation of salt resistance test samples) After adding the stirring bar to a 200ml polystyrene bottle, the example , reference example Alternatively, 3.6 g of each silica sol prepared in the comparative example was added and stirred with a magnetic stirrer. While stirring with the magnetic stirrer, 46.4 g of pure water and 100 g of brine solution with a salt concentration of 6% by mass were added and stirred for 1 hour. This was used as a salt resistance test sample to evaluate the heat resistance and salt resistance of the silica sol when the silica concentration was reduced to 0.5% by mass under a salt concentration of 4% by mass. The pH, electrical conductivity, and DLS average particle size of the aqueous silica sol (silica particles) in the sample were evaluated for the obtained salt resistance test sample. 【0039】 (Evaluation of salt tolerance at room temperature) 150 g of the salt resistance test sample was placed in a 200 ml airtight polystyrene container. After sealing, the polystyrene container was left to stand at 20°C for a predetermined time. Then, the appearance, pH, electrical conductivity, and DLS average particle size of the aqueous silica sol (silica particles) in the sample were evaluated. Salt resistance was evaluated by determining salt resistance based on the DLS average particle size measurement results of aqueous silica sol (silica particles) in the sample after holding it at 20°C for a predetermined time (10 hours) (see salt resistance determination below) and by evaluating its appearance. 【0040】 (Assessment of salt tolerance) A: The ratio of the average DLS particle size after the salt tolerance test to the average DLS particle size before the test is 1.1 or less. B: The ratio of the average DLS particle size after the salt tolerance test to the average DLS particle size before the test is 1.2 to 1.5. C: The ratio of the average DLS particle size after the salt tolerance test to the average DLS particle size before the test is 1.6 to 2.4. D: The ratio of the average DLS particle size after the salt tolerance test to the average DLS particle size before the test is 2.5 to 20.0. E: The ratio of the average DLS particle size after the salt resistance test to the average DLS particle size before the test is 20.1 or higher, or turbidity occurs and solid-liquid separation occurs. The salt resistance test results indicate that A is the most preferable, followed by B, C, D, and E in that order of preference. 【0041】 (High-temperature salt tolerance evaluation - 1) The salt resistance test sample is placed in a 120 ml airtight container made of Teflon®. 65g was placed in a Teflon® container, sealed, and then placed in a 100°C dryer. After being maintained at 100°C for a predetermined time (10 hours), the appearance, pH, electrical conductivity, and DLS average particle size of the aqueous silica sol (silica particles) in the sample were evaluated. High-temperature salt resistance was determined using the same criteria as those used for determining salt resistance in the room-temperature salt resistance evaluation described above. 【0042】 (High-temperature salt tolerance evaluation - 2) Except for setting the dryer temperature to 120°C and the holding time to 10 hours, the high-temperature salt resistance was determined using the same procedure as described above (High-Temperature Salt Resistance Evaluation-1). 【0043】 (Preparation of aqueous silica sol) ( reference Example 1) 1000g of aqueous silica sol (Nissan Chemical Corporation's Snowtex (product name) ST-O, silica concentration 20.5% by mass, average particle size 11.7nm by BET method, average particle size 18.6nm by DLS method) and a magnetic stirrer were added to a 2000ml glass round-bottom flask. While stirring with the magnetic stirrer, the silane compound was prepared to be at a concentration of 0.5 particles / nm relative to the surface area of ​​silica in the aqueous silica sol. 29.4 g of 3-glycidoxypropyltrimethoxysilane (Dynasylan GLYMO, Evonik) was added to achieve the desired result. Subsequently, a condenser running tap water was placed on top of the round-bottom flask, and the aqueous sol was heated to 60°C under reflux. The mixture was held at 60°C for 4 hours, including the heating time, and then cooled. The stirring time after heating to 60°C was 1 to 7 times longer than the stirring time at room temperature. After cooling to room temperature, the aqueous sol was removed, yielding 100 g of aqueous sol containing aqueous silica sol surface-treated with a silane compound. reference The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol in Example 1 were evaluated using the DLS method. (Evaluation of silane bond content) reference The amount of silane bond in the aqueous silica sol of Example 1 was evaluated. Salt tolerance test samples were prepared according to the instructions in "Preparation of Salt Tolerance Test Samples," and after being held at 20°C for 10 hours according to the instructions in "Evaluation of Salt Tolerance at Room Temperature," the samples were removed and their room temperature salt tolerance was evaluated. 【0044】 ( reference Example 2) In an aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation, with an average particle size of 11.7 nm by the BET method and an average particle size of 18.6 nm by the DLS method), the amount of silane compounds was 8.0 particles / nm relative to the surface area of ​​the silica in the aqueous silica sol. 2 Except for adding 149.7g of 3-glycidoxypropyltrimethoxysilane (Dynasylan GLYMO, manufactured by Evonik) to achieve the desired result, reference 1149.7 g of aqueous sol was obtained by the same procedure as in Example 1. reference The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol in Example 2 were evaluated using the DLS method. (Evaluation of silane bond content) reference The amount of silane bond in the aqueous silica sol of Example 2 was evaluated. Salt resistance test samples were prepared according to (Preparation of salt resistance test samples), and after being held at 100°C for 10 hours according to (High temperature salt resistance evaluation - 1), the samples were removed and their high temperature salt resistance was evaluated. 【0045】 ( reference Example 3) In an aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation, with an average particle size of 11.7 nm by the BET method and an average particle size of 18.6 nm by the DLS method), the silane compound was present at 30.8 particles / nm relative to the surface area of ​​the silica in the aqueous silica sol. 2 Except for adding 576.2g of 3-glycidoxypropyltrimethoxysilane (Dynasylan GLYMO, manufactured by Evonik) to achieve the desired result, reference 1576.2 g of aqueous sol was obtained by the same procedure as in Example 1. reference The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol in Example 3 were evaluated using the DLS method. (Evaluation of silane bond content) reference The amount of silane bond in the aqueous silica sol of Example 3 was evaluated. Salt resistance test samples were prepared according to (Preparation of salt resistance test samples), and after being held at 100°C for 10 hours according to (High temperature salt resistance evaluation - 1), the samples were removed and their high temperature salt resistance was evaluated. 【0046】 ( reference Example 4) In an aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation, with an average particle size of 11.7 nm by the BET method and an average particle size of 18.6 nm by the DLS method), the amount of silane compounds relative to the surface area of ​​silica in the aqueous silica sol was 46.2 particles / nm. 2 Except for adding 864.3g of 3-glycidoxypropyltrimethoxysilane (Dynasylan GLYMO, manufactured by Evonik) to achieve the desired result, reference 1864.3 g of aqueous sol was obtained by the same procedure as in Example 1. reference The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol in Example 4 were evaluated using the DLS method. (Evaluation of silane bond content) reference The amount of silane bond in the aqueous silica sol of Example 4 was evaluated. Salt resistance test samples were prepared according to (Preparation of salt resistance test samples), and after being held at 100°C for 10 hours according to (High temperature salt resistance evaluation - 1), the samples were removed and their high temperature salt resistance was evaluated. 【0047】 (Example 5) In an aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation, with an average particle size of 11.7 nm by the BET method and an average particle size of 18.6 nm by the DLS method), the amount of silane compound relative to the surface area of ​​silica in the aqueous silica sol was 0.5 particles / nm. 2 Except for adding 5.4g of methyltrimethoxysilane (KBM-13, manufactured by Shin-Etsu Chemical Co., Ltd.) to achieve the desired result, reference 5.4 g of aqueous sol was obtained by the same procedure as in Example 1. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol of Example 5 were evaluated by the DLS method. The amount of silane bonded material in the aqueous silica sol of Example 5 was evaluated according to (Evaluation of Silane Bonding Amount). Salt tolerance test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their room temperature salt tolerance was evaluated. 【0048】 (Example 6) Aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation, by the BET method) For silica with an average particle size of 11.7 nm (average particle size of 18.6 nm by DLS method), the silane compound is present at a density of 0.5 particles / nm relative to the surface area of ​​silica in aqueous silica sol. 2 Except for adding 4.8g of dimethyldimethoxysilane (KBM-22, manufactured by Shin-Etsu Chemical Co., Ltd.) to achieve the desired result, reference 4.8 g of aqueous sol was obtained by the same procedure as in Example 1. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol of Example 6 were evaluated by the DLS method. The amount of silane bonded material in the aqueous silica sol of Example 6 was evaluated according to the (evaluation of silane bond amount) procedure. Salt tolerance test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their room temperature salt tolerance was evaluated. 【0049】 (Example 7) Aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation), by the BET method The average particle size is 11.7 nm (average particle size 18.6 nm by DLS method), and the amount of silane compounds in silica in aqueous silica sol is 0.5 particles / nm relative to the surface area of ​​silica. 2 Except for adding 9.8g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KBM-303, manufactured by Shin-Etsu Chemical Co., Ltd.) to achieve the desired result, reference 100 9.8 g of aqueous sol was obtained by the same procedure as in Example 1. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol of Example 7 were evaluated by the DLS method. The amount of silane bonded material in the aqueous silica sol of Example 7 was evaluated according to the (evaluation of silane bond amount) procedure. Salt tolerance test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their room temperature salt tolerance was evaluated. 【0050】 (Example 8) In an aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation, with an average particle size of 11.7 nm by the BET method and an average particle size of 18.6 nm by the DLS method), the amount of silane compound relative to the surface area of ​​silica in the aqueous silica sol was 0.5 particles / nm. 2 Except for adding 8.6g of trifluoropropyltrimethoxysilane (KBM-7103, manufactured by Shin-Etsu Chemical Co., Ltd.) to achieve the desired result, reference 1008.6 g of aqueous sol was obtained using the same procedure as in Example 1. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol of Example 8 were evaluated by the DLS method. The amount of silane bonded material in the aqueous silica sol of Example 8 was evaluated according to the (evaluation of silane bond amount) procedure. Salt tolerance test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their room temperature salt tolerance was evaluated. 【0051】 (Example 9) In an aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation, with an average particle size of 11.7 nm by the BET method and an average particle size of 18.6 nm by the DLS method), the amount of silane compounds was 8.0 particles / nm relative to the surface area of ​​the silica in the aqueous silica sol. 2 Except for adding a solution prepared by pre-mixing 114.1g of lactic acid and 140.2g of aminopropyltriethoxysilane (KBE-903, manufactured by Shin-Etsu Chemical Co., Ltd.) and stirring for 30 minutes, the following was done: reference 1254.3 g of aqueous sol was obtained by the same procedure as in Example 1. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol of Example 9 were evaluated by the DLS method. The amount of silane bonded material in the aqueous silica sol of Example 9 was evaluated according to the (evaluation of silane bond amount) procedure. Salt tolerance test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their room temperature salt tolerance was evaluated. 【0052】 (Example 10) When 114.1 g of lactic acid was added to silica in an aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation, with an average particle size of 11.7 nm by the BET method and an average particle size of 18.6 nm by the DLS method), and the mixture was stirred with a magnetic stirrer, the amount of silane compound was found to be 8.0 particles / nm relative to the surface area of ​​the silica in the aqueous silica sol. 2 Except for adding 113.6g of aminopropyltrimethoxysilane (KBM-903, manufactured by Shin-Etsu Chemical Co., Ltd.) to achieve this, reference 1227.7 g of aqueous sol was obtained by the same procedure as in Example 1. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol of Example 10 were evaluated by the DLS method. The amount of silane bonded material in the aqueous silica sol of Example 10 was evaluated according to the (evaluation of silane bond amount) procedure. Salt tolerance test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their room temperature salt tolerance was evaluated. 【0053】 (Example 11) When 228.2 g of lactic acid was added to silica in an aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation, with an average particle size of 11.7 nm by the BET method and an average particle size of 18.6 nm by the DLS method), and the mixture was stirred with a magnetic stirrer, the amount of silane compound was found to be 8.0 particles / nm relative to the surface area of ​​the silica in the aqueous silica sol. 2 Except for adding 140.9g of aminoethylaminopropyltrimethoxysilane (KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.) to achieve the desired result, reference 1369.1 g of aqueous sol was obtained by the same procedure as in Example 1. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol from Example 11 were evaluated using the DLS method. The amount of silane bonded material in the aqueous silica sol of Example 11 was evaluated according to the (evaluation of silane bond amount) procedure. Salt resistance test samples were prepared according to (Preparation of salt resistance test samples), and after being held at 120°C for 10 hours according to (High temperature salt resistance evaluation - 2), the samples were removed and their high temperature salt resistance was evaluated. 【0054】 (Example 12) When 228.2 g of lactic acid was added to silica in an aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation, with an average particle size of 11.7 nm by the BET method and an average particle size of 18.6 nm by the DLS method), the mixture was stirred with a magnetic stirrer, and the amount of silane compound was found to be 8.0 particles / nm relative to the surface area of ​​the silica in the aqueous silica sol. 2 Except for adding 130.7g of aminoethylaminopropylmethyldimethoxysilane (KBM-602, manufactured by Shin-Etsu Chemical Co., Ltd.) to achieve the desired result, reference 1358.9 g of aqueous sol was obtained by the same procedure as in Example 1. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol of Example 12 were evaluated by the DLS method. The amount of silane bonded material in the aqueous silica sol of Example 12 was evaluated according to the (evaluation of silane bond amount) procedure. Salt resistance test samples were prepared according to (Preparation of salt resistance test samples), and after being held at 120°C for 10 hours according to (High temperature salt resistance evaluation - 2), the samples were removed and their high temperature salt resistance was evaluated. 【0055】 ( reference Example 13) In an aqueous silica sol (Snowtex (product name) ST-OXS, manufactured by Nissan Chemical Corporation; silica concentration 10.5% by mass; average particle size 5.0 nm by BET method; average particle size 8.1 nm by DLS method), the amount of silane compound relative to the silica surface area in the aqueous silica sol was 8.0 particles / nm. 2 Except for adding 179.4g of 3-glycidoxypropyltrimethoxysilane (Dynasylan GLYMO, manufactured by Evonik) to achieve the desired result, reference 1179.4 g of aqueous sol was obtained by the same procedure as in Example 1. reference The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol in Example 13 were evaluated using the DLS method. (Evaluation of silane bond content) reference The amount of silane bond in the aqueous silica sol of Example 13 was evaluated. Salt resistance test samples were prepared according to (Preparation of salt resistance test samples), and after being held at 100°C for 10 hours according to (High temperature salt resistance evaluation - 1), the samples were removed and their high temperature salt resistance was evaluated. 【0056】 ( reference Example 14) In an aqueous silica sol (Snowtex (product name) ST-OL, manufactured by Nissan Chemical Corporation; silica concentration 20.5% by mass; average particle size 45.0 nm by BET method; average particle size 78.0 nm by DLS method), the silane compound was present at 32.7 particles / nm relative to the surface area of ​​the silica in the aqueous silica sol. 2Except for adding 159.0g of 3-glycidoxypropyltrimethoxysilane (Dynasylan GLYMO, manufactured by Evonik) to achieve the desired result, reference 1159.0 g of aqueous sol was obtained by the same procedure as in Example 1. reference The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol in Example 14 were evaluated using the DLS method. (Evaluation of silane bond content) reference The amount of silane bond in the aqueous silica sol of Example 14 was evaluated. Salt resistance test samples were prepared according to (Preparation of salt resistance test samples), and after being held at 100°C for 10 hours according to (High temperature salt resistance evaluation - 1), the samples were removed and their high temperature salt resistance was evaluated. 【0057】 (Comparative Example 1) Aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation) was used as the aqueous silica sol for Comparative Example 1. The pH, electrical conductivity, viscosity, and DLS average particle size of the aqueous silica sol (silica particles) of Comparative Example 1 were evaluated. The amount of silane bonded material in the aqueous silica sol of Comparative Example 1 was evaluated according to (Evaluation of Silane Bond Amount). Salt tolerance test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their room temperature salt tolerance was evaluated. 【0058】 (Comparative Example 2) reference 1149.7 g of aqueous silica sol was obtained by the same procedure as in Example 2. reference In Example 2, 200 g of aqueous silica sol was mixed with 800 g of pure water, filtered by ultrafiltration until 200 g was discharged, and then another 800 g of pure water was added. This process was repeated four times to obtain 200 g of aqueous silica sol from which free silane had been removed. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol of Comparative Example 2 were evaluated by the DLS method. The amount of silane bonded material in the aqueous silica sol of Comparative Example 2 was evaluated according to (Evaluation of Silane Bond Amount). Salt resistance test samples were prepared according to (Preparation of salt resistance test samples), and after being held at 100°C for 10 hours according to (High temperature salt resistance evaluation - 1), the samples were removed and their high temperature salt resistance was evaluated. 【0059】 (Comparative Example 3) In an aqueous silica sol (Snowtex (product name) ST-O, manufactured by Nissan Chemical Corporation, with an average particle size of 11.7 nm by the BET method and an average particle size of 18.6 nm by the DLS method), the amount of silane compound relative to the surface area of ​​silica in the aqueous silica sol was 2.0 particles / nm. 2 Except for adding 35.1g of methyltrimethoxysilane (KBM-13, manufactured by Shin-Etsu Chemical Co., Ltd.) to achieve the desired result, reference 1035.1 g of aqueous sol was obtained by the same procedure as in Example 1. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol of Comparative Example 3 were evaluated by the DLS method. The amount of silane bonded material in the aqueous silica sol of Comparative Example 3 was evaluated according to the (evaluation of silane bond amount) procedure. Salt tolerance test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their room temperature salt tolerance was evaluated. 【0060】 (Comparative Example 4) After adding 1000g of aqueous silica sol (Nissan Chemical Corporation's Snowtex (product name) ST-O, silica concentration = 20.5% by mass, BET method average particle size 11.7nm, DLS average particle size 18.6nm) and a magnetic stirrer to a 2000ml glass round-bottom flask, the mixture was stirred with a magnetic stirrer until the silane compound was 8.0 particles / nm relative to the surface area of ​​the silica in the aqueous silica sol. 2 149.7 g of 3-glycidoxypropyltrimethoxysilane (Dynasylan GLYMO, manufactured by Evonik) was added to obtain 1149.7 g of aqueous sol. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol of Comparative Example 4 were evaluated by the DLS method. The amount of silane bonded material in the aqueous silica sol of Comparative Example 4 was evaluated according to the (evaluation of silane bond amount) procedure. Salt tolerance test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their room temperature salt tolerance was evaluated. 【0061】 (Comparative Example 5) 1254.3 g of aqueous silica sol was obtained by the same procedure as in Example 9. 200 g of the aqueous silica sol from Example 9 was mixed with 800 g of pure water, filtered by ultrafiltration until 200 g was discharged, and then another 800 g of pure water was added. This process was repeated four times to obtain 200 g of aqueous silica sol from which free silane had been removed. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol of Comparative Example 5 were evaluated by the DLS method. The amount of silane bonded material in the aqueous silica sol of Comparative Example 5 was evaluated according to (Evaluation of Silane Bond Amount). Salt tolerance test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their room temperature salt tolerance was evaluated. 【0062】 (Comparative Example 6) 1227.7 g of aqueous silica sol was obtained by the same procedure as in Example 10. 200 g of the aqueous silica sol from Example 10 was mixed with 800 g of pure water, filtered by ultrafiltration until 200 g was discharged, and then 800 g of pure water was added again. The same procedure was repeated four times to obtain 200 g of aqueous silica sol from which free silane had been removed. The pH, electrical conductivity, viscosity, and average particle size of the aqueous silica sol of Comparative Example 6 were evaluated by the DLS method. The amount of silane bonded material in the aqueous silica sol of Comparative Example 6 was evaluated according to (Evaluation of Silane Bond Amount). 【0063】 (Comparative Example 7) Aqueous silica sol (Snowtex (product name) ST-OXS, manufactured by Nissan Chemical Corporation) was used as the aqueous silica sol for Comparative Example 7. The pH, electrical conductivity, viscosity, and DLS average particle size of the aqueous silica sol (silica particles) of Comparative Example 7 were evaluated. The amount of silane bonded material in the aqueous silica sol of Comparative Example 7 was evaluated according to the (evaluation of silane bond amount) procedure. Salt tolerance test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their room temperature salt tolerance was evaluated. 【0064】 (Comparative Example 8) Aqueous silica sol (Snowtex (product name) ST-OL, manufactured by Nissan Chemical Corporation) was used as the aqueous silica sol for Comparative Example 8. The pH, electrical conductivity, viscosity, and DLS average particle size of the aqueous silica sol (silica particles) of Comparative Example 8 were evaluated. The amount of silane bonded material in the aqueous silica sol of Comparative Example 8 was evaluated according to (Evaluation of Silane Bond Amount). Salt tolerance test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their room temperature salt tolerance was evaluated. Brine test samples were prepared according to (Preparation of salt tolerance test samples), and after being held at 20°C for 10 hours according to (Evaluation of salt tolerance at room temperature), the samples were removed and their salt tolerance at room temperature was evaluated. Examples are shown in Tables 1-6. (Reference example) The composition (component concentration) and salt resistance test results of the aqueous silica sol are shown in Tables 7 and 8, respectively. The composition (component concentration) and salt resistance test results of the aqueous silica sol of the comparative example are also shown in Tables 7 and 8. The amount of bound silane in Tables 1-3 is the "number of moles of silicon atoms of silane bound to the surface of inorganic oxide particles," the amount of free silane is the "number of moles of silicon atoms in the hydrolysate of hydrolyzable silane in the dispersion medium," and the amount of silane added is the mass of the silane compound added in each example, reference example, and comparative example (unit: atoms / nm). 2 The "free silane amount" was obtained by subtracting the "bound silane amount" from the "silane addition amount". Furthermore, since Examples 9-12 and Comparative Examples 5-6 contain nitrogen, the amount of silane bonded material ("bonded silane") was calculated from the nitrogen content according to the "(measurement of nitrogen content)" procedure described above. Similarly, since Examples 5-8, Reference Examples 1-4, Reference Examples 13-14, and Comparative Examples 1-4 do not contain nitrogen, the amount of silane bonded material ("bonded silane") was calculated from the carbon content according to the "(measurement of carbon content)" procedure described above. Even if the "amount of silane added" is unknown, the "total amount of silane (equivalent to the amount of silane added)" can be calculated by using "aqueous silica sol with free silane removed" instead of "aqueous silica sol with free silane removed" in the above (measurement of carbon content) or (measurement of nitrogen content). Specifically, for Examples 5-8, Reference Examples 1-4, Reference Examples 13-14, and Comparative Examples 1-4, which do not contain nitrogen, the carbon content is measured and the "amount of silane added" is calculated using the formula described in (measurement of carbon content) above. For Examples 9-12 and Comparative Examples 5-6, which contain nitrogen, the nitrogen content is measured and the "amount of silane added" is calculated using the formula described in (measurement of nitrogen content) above. The "amount of free silane" can then be calculated by subtracting the "amount of bound silane" from the "amount of silane added". (The "amount of bound silane" is calculated using the method described in (measurement of carbon content) or (measurement of nitrogen content) above.) 【0065】 [Table 1] 【0066】 [Table 2] 【0067】 [Table 3] 【0068】 [Table 4] 【0069】 [Table 5] 【0070】 [Table 6] 【0071】 [Table 7] 【0072】 [Table 8] The types (symbols) of silane compounds in the table represent the following: • LTAC: Lauryltrimethylammonium chloride ("Trade name: Katiogen TML"), active ingredient 30.0%, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. • GPS: 3-Glycidoxypropyltrimethoxysilane ("Trade name Dynasylan GLYMO"), manufactured by Evonik Co., Ltd. • MTMS: Methyltrimethoxysilane (product name KBM-13), manufactured by Shin-Etsu Chemical Co., Ltd. • DMS: Dimethyldimethoxysilane (product name KBM-22), manufactured by Shin-Etsu Chemical Co., Ltd. • EPCHS: (3,4-Epoxycyclohexyl)ethyltrimethoxysilane "Trade name KBM-303", manufactured by Shin-Etsu Chemical Co., Ltd. • TFPS: Trifluoropropyltrimethoxysilane ("Trade name KBM-7103"), manufactured by Shin-Etsu Chemical Co., Ltd. • APTES: 3-aminopropyltriethoxysilane (product name KBE-903), manufactured by Shin-Etsu Chemical Co., Ltd. • APTMS: 3-aminopropyltrimethoxysilane (product name KBM-903), manufactured by Shin-Etsu Chemical Co., Ltd. AEAPTMS: N-2-(aminoethyl)-3-aminopropyltrimethoxysilane ("Trade name KBM-603"), manufactured by Shin-Etsu Chemical Co., Ltd. AEAPMDMS:N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane ("Trade name KBM-602"), manufactured by Shin-Etsu Chemical Co., Ltd. 【0073】 (Measurement of the binding state of free silanes) The aqueous silica sol of the present invention is expected to have a greater effect in improving the stability of silica particles depending on the form of the free silane it contains. The form of the free silane was analyzed by placing 6 g of aqueous silica sol into a 15 ml centrifugal filter unit (product name Amicon Ultra-15, Merck KGaA), centrifuging it at a centrifugal force of 2770 G for 20 minutes, and analyzing the liquid containing the free silane discharged to the bottom of the unit by Si-NMR, and calculating the content ratio of T structures or D structures. implementation Example 9 ,10, Reference example 2, The T structure was measured for 13 and 14, and the measurement results are shown in Table 9. The D structure was measured for Example 12, and the measurement results are shown in Table 10. 【0074】 [Table 9] [Table 10] 【0075】 (Measurement of the bonding state of bonded silanes) The aqueous silica sol of the present invention is expected to further improve the stability of silica particles because some of the silane compound is bound to the surface of the silica particles. The morphology of the bound silane was analyzed by analyzing the liquid obtained (after removal of free silane) by Si-NMR and calculating the proportion of Q structures. implementation Example 5 , 6, 7, 8, 9, 10, 11, 12, Reference example 2,The Q structure was measured for items 13, 14, and comparative examples 1, 7, and 8, and the measurement results are shown in Table 11. 【0076】 [Table 11] 【0077】 (Specific surface area calculated from water vapor adsorption / Specific surface area calculated from nitrogen gas adsorption) The aqueous silica sol of the present invention is expected to have a greater effect in improving the stability of silica particles because the silica particle surface is replaced from silanol groups to silane compounds having functional groups. The value obtained by dividing the specific surface area calculated from the amount of water vapor adsorbed by the amount of nitrogen gas adsorbed, (specific surface area calculated from the amount of water vapor adsorbed) / (specific surface area calculated from the amount of nitrogen gas adsorbed), indicates that the silica particle surface is replaced from silanol groups to silane compounds having functional groups. The amount of water vapor adsorbed and the amount of nitrogen gas adsorbed were analyzed according to the procedures of (measurement of water vapor adsorption) and (measurement of nitrogen gas adsorption). implementation Example 5 7, 8, Reference examples 1, 2, For samples 13, 14, and Comparative Examples 1, 3, 7, and 8, the amount of water vapor adsorbed and nitrogen gas adsorbed was measured. The values ​​obtained by dividing the value after silane compound treatment by the value before silane compound treatment using the formula (specific surface area calculated from water vapor adsorption) / (specific surface area calculated from nitrogen gas adsorption) are shown in Table 12. 【0078】 [Table 12] [Industrial applicability] 【0079】 This invention can provide a dispersion of inorganic oxide particles, particularly a dispersion of silica particles, that exhibits high dispersion stability even under high temperature and high salinity conditions.

Claims

[Claim 1] A dispersion comprising silane-bonded silica-containing inorganic oxide particles surface-modified with hydrolyzable silane as a dispersed phase, wherein the dispersion medium contains the hydrolysate of the hydrolyzable silane, and the ratio of (number of moles of silicon atoms in the hydrolysate of hydrolyzable silane in the dispersion medium) / (number of moles of silicon atoms of silane bonded to the surface of the inorganic oxide particles) is 0.2 to 30, comprising the silane-bonded silica-containing inorganic oxide particles. The silica-containing inorganic oxide particles in the above-mentioned silane-bonded silica-containing inorganic oxide particles are silica particles in an aqueous silica sol starting from water glass. The above hydrolyzable silane is a silane compound of the following formula (1), 【Chemistry 1】 (In formula (1), R3 is an organic group having an alkyl group, a halogenated alkyl group, an epoxy group, or an amino group and is bonded to a silicon atom by a Si-C bond, except for the glycidoxypropyl group.) R4 represents an alkoxy group, an acyloxy group, or a halogen group, and a is an integer from 1 to 3. The hydrolyzable silane hydrolysates in the dispersion medium include silane compounds in which the hydrolyzable silane compounds in formula (1) where a is an integer of 1 show T0, T1, T2, and T3 structures where the ratio of bridging oxygen between silicon atoms is 0 / 2, 1 / 2, 2 / 2, and 3 / 2 per silicon atom in Si-NMR observation, and the (T2+T3) / (T0+T1) ratio is a specific value (2 to 15), or the (T1+T2+T3) / (T0) ratio is a specific value (5 to 100), or For hydrolyzable silane hydrolysates in a dispersion medium, the hydrolyzable compounds of silane compounds in formula (1) where a is an integer of 2 show D0, D1, and D2 structures where the ratio of bridging oxygen between silicon atoms is 0 / 2, 1 / 2, and 2 / 2 per silicon atom as observed by Si-NMR, ( A dispersion containing a silane compound having a D1 + D2 / (D0) ratio of 0.1 to 10, or a (D2) / (D0 + D1) ratio of 0.01 to 10. [Claim 2] The silane-bonded silica-containing inorganic oxide particles are silica particles with an average particle diameter of 5 nm to 100 nm or inorganic oxide particles with an average particle diameter of 5 nm to 100 nm. The dispersion according to claim 1, wherein the inorganic oxide particles are composite metal oxide particles of silica and at least one metal oxide selected from the group consisting of alumina, tin oxide, zirconium oxide, titanium oxide, and antimony oxide, or composite oxide particles having a core-shell structure of silica and at least one metal oxide selected from the group consisting of alumina, tin oxide, zirconium oxide, titanium oxide, and antimony oxide. [Claim 3] The dispersion according to claim 1, wherein in Q4, where the number of bridging oxygen atoms between silicon atoms in silica particles is 4 / 2 per silicon atom as observed by Si-NMR, Q4 is 76% to 92%. [Claim 4] The amount of bonded silanes in the above-mentioned silane-bonded silica-containing inorganic oxide particles is 0.3 to 5.9 per nm. ２ The dispersion according to claim 1. [Claim 5] The amount of free silane, which is a hydrolysis product of the hydrolyzable silane, in the above dispersion medium is 0.1 to 40.3 cells / nm. ２ The dispersion according to claim 1. [Claim 6] The dispersion according to claim 1, wherein the amount of water vapor adsorbed onto the silane-bonded silica-containing inorganic oxide particles is divided by the amount of nitrogen gas adsorbed, and the ratio (specific surface area calculated from the amount of water vapor adsorbed) / (specific surface area calculated from the amount of nitrogen gas adsorbed) is 0.15 to 0.95 compared to the silica-containing inorganic oxide particles before the addition of the silane compound, and the silica-containing inorganic oxide particles include silane-bonded silica-containing inorganic oxide particles and / or silica-containing inorganic oxide particles that are not silane-bonded. [Claim 7] The dispersion according to claim 1, wherein, in a room temperature salt resistance evaluation in which a mixture obtained by mixing the above-mentioned aqueous dispersion of silane-bonded silica-containing inorganic oxide particles with a brine solution to obtain a silica concentration of 0.5% by mass and a salt concentration of 4% by mass is held at 20°C for 10 hours, the ratio of the DLS average particle size after the salt resistance test (storage) to the DLS average particle size before the salt resistance test (storage) is 2.4 or less. [Claim 8] The following steps (A) through (B): (A) Step: A step to obtain an aqueous dispersion of the above-mentioned silane-bonded silica-containing inorganic oxide particles and / or non-silane-bonded silica-containing inorganic oxide particles. (B) Step: A method for producing a dispersion according to any one of claims 1 to 7, comprising the steps of adding hydrolyzable silane to an aqueous dispersion of silane-bonded silica-containing inorganic oxide particles and / or non-silane-bonded silica-containing inorganic oxide particles in a ratio of the number of silane particles per particle surface area in the range of 0.3 to 100 particles / nm², stirring at room temperature, raising the temperature to within 20 to 99°C, and stirring after raising the temperature for a time that is 1 to 100 times longer than the stirring time at room temperature. [Claim 9] A method for producing a dispersion according to claim 8, comprising, before step (B) above, a step of adjusting the pH of the aqueous dispersion of silane-bonded silica-containing inorganic oxide particles to 2.0 to 6.

5. [Claim 10] After step (B) above, step (C) is performed: A method for producing a dispersion using an organic solvent as a dispersion medium, according to claim 8, comprising the step of (C) replacing the aqueous medium of the dispersion obtained in step (B) with an organic solvent.

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