Silica sol containing additive, and method for producing same

Abstract

[Problem] To provide a stable silica sol which contains an additive, wherein scattering intensity ratios among scattering vectors are within a specific range as determined by a small-angle X-ray scattering method. [Solution] An additive-containing silica sol which is characterized in that the scattering intensity (I) with respect to a scattering vector (q) of the additive-containing silica sol as determined by a small-angle scattering method using an X-ray satisfies formula (2) and formula (3). wi="149.6" / > In formula (2) and formula (3), IB 0 represents the scattering intensity at the time when the scattering vector (q) nm-1 of a silica sol before the addition of an additive is 0.05 in cases where the silica particle concentration in the silica sol is 3.5% by mass; IB max represents the scattering intensity at which the scattering vector (q) nm-1 of the silica sol before the addition of the additive is maximum in cases where the silica particle concentration in the silica sol is 3.5% by mass; IA 0 represents the scattering intensity at the time when the scattering vector (q) nm-1 of a silica sol after the addition of the additive is 0.05 in cases where the silica particle concentration in the silica sol is 3.5% by mass; and IA max represents the scattering intensity at which the scattering vector (q) nm-1 of the silica sol after the addition of the additive is maximum in cases where the silica particle concentration in the silica sol is 3.5% by mass.　With respect to the HAZE value of a silica sol, which uses a salt solution having a salt concentration of 4% by mass as a dispersion medium and has a silica particle concentration of 0.1% by mass, the HAZE value after 24 hours of storage at 20°C is lower than the HAZE value before the addition of an additive.

Description

Silica sol containing additives and method for producing the same

[0001] The present invention relates to a highly stable dispersion of silica particles based on the charge on the particle surface as determined by small-angle X-ray scattering.

[0002] Small-angle X-ray scattering is used for structural analysis of a few nanometers to a few tens of nanometers. In this scattering method, an energy beam is irradiated onto a sample and the scattering intensity is evaluated according to the scattering angle. When X-rays are used, X-ray scattering occurs. In the case of short-wavelength X-rays, scattering from the structure occurs at small angles of a few degrees or less, resulting in small-angle scattering, which is used for structural analysis. Light scattering can appear as fluctuations in the refractive index (dielectric constant), while X-ray scattering can appear as fluctuations in electron density. In small-angle X-ray scattering, the scattering vector q is q = 4π sin θ / λ, where 2θ is the scattering angle and λ is the wavelength of the incident X-rays. The scattering intensity I corresponding to the scattering vector q is related to fluctuations in electron density in the sample, and can detect the shape and surface state of nanoscale structures. For example, in a semiconductor insulating material containing silicon atoms, carbon atoms, and oxygen atoms, silica particles are 9.5 to 30%, and the scattering vector q in small-angle X-ray scattering measurement is 0.1 nm. －１ Scattering intensity I １ (q), the scattering vector q is 0.2 nm －１ Scattering intensity I ２ The ratio (I １ (q) / I ２ An insulating material for semiconductors having a coefficient of electrical conductivity (q) of 1.35 or less has been reported (see Patent Document 1).

[0003] JP 2014-067829 A

[0004] Incidentally, a sol (silica sol) in which silica particles are dispersed in a dispersion medium generates an appropriate electrical repulsive force between the silica particles due to the charge on the surface of the silica particles, and the particles can be dispersed in the dispersion medium without agglomeration. However, when the dispersion medium is an aqueous medium or an organic solvent containing ionic components, the electrical balance between the charge on the surface of the silica particles and the dispersion medium is disrupted, which may cause aggregation. Therefore, there has been a demand for a silica sol that can be dispersed without agglomeration even when the dispersion medium is an aqueous medium or an organic solvent containing ionic components.

[0005] The present invention has been made in view of the above, and aims to provide a silica sol that can be dispersed without aggregation even when the dispersion medium is an aqueous medium or an organic solvent containing ionic components, and a method for producing the silica sol.

[0006] In order to achieve the above-mentioned object, the present inventors have focused on the fact that the charge on the surface of silica particles can be changed by adding an additive to silica sol, and that the charge on the surface of the particles affects the dispersion state of the silica particles in a dispersion medium. They have then found that a stable silica sol can be obtained by satisfying a specific condition for the scattering intensity (I) of a specific scattering vector of an additive-containing silica sol determined by a small-angle scattering method using X-rays, and have completed the present invention.

[0007] That is, in a first aspect, the present invention relates to an additive-containing silica sol, characterized in that the scattering intensity (I) with respect to the scattering vector (q) of the additive-containing silica sol determined by a small-angle scattering method using X-rays satisfies the following formulas (2) and (3): Here, in the formula (2) and the formula (3), I Ｂ ０ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol before adding the additive is 3.5 mass % －１ represents the scattering intensity when is 0.05, and I Ｂ ｍａｘ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol before adding the additive is 3.5 mass % －１ represents the scattering intensity at its maximum value, and I Ａ ０ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol after adding the additive is 3.5 mass% －１ represents the scattering intensity when is 0.05, and I Ａ ｍａｘ is the scattering vector (q) nm of the silica sol after adding the additive when the silica particle concentration is 3.5 mass% －１represents the scattering intensity at which the value is maximum. As a second aspect, the present invention relates to the silica sol according to the first aspect, wherein, with respect to the haze value of a silica sol using salt water having a salt concentration of 4% by mass as a dispersion medium and having a silica particle concentration of 0.1% by mass, the haze value after storage at 20°C for 24 hours from the time of production is lower than the haze value of the silica sol before the addition of an additive after storage at 20°C for 24 hours from the time of production. As a third aspect, the present invention relates to the silica sol according to the first or second aspect, wherein, with respect to the particle size measured by dynamic light scattering of a silica sol using salt water having a salt concentration of 4% by mass as a dispersion medium and having a silica particle concentration of 0.1% by mass, the ratio of the particle size measured by dynamic light scattering after storage at 20°C for 24 hours to the particle size measured by dynamic light scattering at the time of production is lower than the ratio of the particle size measured by dynamic light scattering after storage at 20°C for 24 hours to the particle size measured by dynamic light scattering at the time of production of the silica sol before the addition of the additive. As a fourth aspect, the present invention relates to the silica sol according to any one of the first to third aspects, wherein the additive is an antioxidant. As a fifth aspect, the present invention relates to the silica sol according to any one of the first to third aspects, in which the additive is a hydrolyzable silane, a sugar, an organic acid or a salt thereof, a sulfite, a thiocyanate, a mercapto organic acid or a salt thereof, a surfactant, or a polyhydroxy compound. As a sixth aspect, the present invention relates to the silica sol according to any one of the first to third aspects, in which the additive is a hydrolyzable silane, a sugar, an organic acid or a salt thereof, a sulfite, a thiocyanate, a mercapto organic acid or a salt thereof, a surfactant, or a polyhydroxy compound. (In formula (1), R １ are organic groups having a cationic functional group or anionic functional group, and are bonded to a silicon atom by a Si—C bond, and R ２each represent an alkoxy group, an acyloxy group, or a halogen atom, and a represents an integer of 1 to 3.) The present invention relates to a silica sol according to a fifth aspect, wherein the cationic functional group is an amino group. The present invention relates to a silica sol according to a seventh aspect, wherein the cationic functional group is an amino group. The present invention relates to a silica sol according to a sixth aspect, wherein the anionic functional group is a glycidoxy group. The present invention relates to a silica sol according to a ninth aspect, wherein the sugar is sorbitol, glucose, or arabinose. The present invention relates to a silica sol according to a tenth aspect, wherein the organic acid or a salt thereof is gluconic acid, lactic acid, or thioglycolic acid, or a salt thereof. The present invention relates to a silica sol according to a fifth aspect, wherein the sulfite is pyrosulfite. The present invention relates to a silica sol according to a twelfth aspect, wherein the thiocyanate is sodium thiocyanate. The present invention relates to a silica sol according to a thirteenth aspect, wherein the mercaptoorganic acid or a salt thereof is mercaptoacetate or an ammonium salt thereof.

[0023] As a fourteenth aspect, the present invention relates to the silica sol according to the fifth aspect, in which the surfactant is at least one surfactant selected from the group consisting of anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants, and the surfactant contains at least an anionic surfactant, a nonionic surfactant, or both. As a fifteenth aspect, the present invention relates to the silica sol according to the fifth aspect, in which the polyhydroxy compound is ascorbic acid. As a sixteenth aspect, the present invention relates to the silica sol according to any one of the first to fifteenth aspects, in which the dispersion medium of the silica sol is an aqueous medium having a pH of 1 to 10, brine having a salt concentration of 0.1 to 4.0 mass %, or an organic solvent.

[0008] According to a seventeenth aspect, the present invention relates to a method for producing an additive-containing silica sol according to any one of the first to sixteenth aspects, the method comprising the step of adjusting, by incorporating an additive into the silica sol, a scattering intensity (I) relative to a scattering vector (q) of the additive-containing silica sol determined by a small-angle scattering method using X-rays so as to satisfy the following formulas (2) and (3): Here, in the formula (2) and the formula (3), I Ｂ ０is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol before adding the additive is 3.5 mass % －１ represents the scattering intensity when is 0.05, and I Ｂ ｍａｘ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol before adding the additive is 3.5 mass % －１ represents the scattering intensity at its maximum value, and I Ａ ０ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol after adding the additive is 3.5 mass% －１ represents the scattering intensity when is 0.05, and I Ａ ｍａｘ is the scattering vector (q) nm of the silica sol after adding the additive when the silica particle concentration is 3.5 mass% －１ represents the scattering intensity at its maximum value.

[0009] According to the present invention, it is possible to provide a silica sol that can be stably dispersed without aggregation even when the dispersion medium is an aqueous medium or an organic solvent containing ionic components, and a method for producing the same.

[0010] 1 shows the results of small-angle X-ray scattering measurement of the silica sols obtained in Examples 1, 10, and 11. FIG. 2 shows an enlarged view of small-angle X-ray scattering measurement of the silica sols obtained in Examples 1, 10, and 11. FIG. 3 shows the results of small-angle X-ray scattering measurement of the silica sols obtained in Comparative Examples 1, 2, and 3. FIG. 4 shows an enlarged view of small-angle X-ray scattering measurement of the silica sols obtained in Comparative Examples 1, 2, and 3. FIG. 5 shows the results of small-angle X-ray scattering measurement of the silica sols obtained in Example 12 and Comparative Example 2. FIG. 6 shows the results of small-angle X-ray scattering measurement of the silica sols obtained in Example 12 and Comparative Example 2. FIG. 7 shows the results of small-angle X-ray scattering measurement of the silica sols obtained in Example 13 and Comparative Example 3. FIG. 8 shows an enlarged view of small-angle X-ray scattering measurement of the silica sols obtained in Example 13 and Comparative Example 3.

[0011] The present invention provides an additive-containing silica sol, characterized in that the scattering intensity (I) relative to the scattering vector (q) of the additive-containing silica sol, determined by a small-angle scattering method using X-rays, satisfies the following formulas (2) and (3): Here, in the formula (2) and the formula (3), I Ｂ ０ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol before adding the additive is 3.5 mass % －１ represents the scattering intensity when is 0.05, and I Ｂ ｍａｘ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol before adding the additive is 3.5 mass % －１ represents the scattering intensity at its maximum value, and I Ａ ０ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol after adding the additive is 3.5 mass% －１ represents the scattering intensity when is 0.05, and I Ａ ｍａｘ is the scattering vector (q) nm of the silica sol after adding the additive when the silica particle concentration is 3.5 mass% －１ represents the scattering intensity at its maximum value.

[0012] Scattering vector (q) nm －１ indicates the direction in which the scattering angle 2θ increases from a scattering angle of approximately 0°, and the measurement range by the small-angle scattering method is up to approximately 5°. －１ The scattering intensity (I ｍａｘ ) is the scattering vector (q) nm －１ The scattering intensity (I ０ ) can be shown as a percentage.

[0013] Scattering intensity (I ｍａｘ ) is the scattering vector (q) nm －１ The scattering intensity (I ０ ) or more, and the scattering vector (q) nm －１ The scattering intensity (I ｍａｘ) is the scattering vector (q) nm －１ is the scattering intensity (I ０ ) the scattering vector (q) nm －１ This is the value of the scattering intensity (I) observed at 0.05 or more. ｍａｘ ) is the scattering intensity (I ０ ) and the scattering intensity (I ０ ) the scattering vector (q) nm －１ is derived from the lower limit of measurement of the measuring device, for example, 0.05 nm －１ However, 0.05 nm －１ However, it is not limited to the above.

[0014] As the concentration of silica particles in a solution increases, interparticle interactions emerge, resulting in order in the spatial distribution of silica particles. In such cases, in small-angle X-ray scattering, the intensity near the scattering vector 0 decreases, and a peak appears in the (q) region corresponding to the order. However, when the particle concentration is the same, the intensity near the scattering vector 0 decreases as the particle charge increases. Since small-angle X-ray scattering measurement cannot measure the intensity at a scattering vector of 0, in the present invention, the charge of silica particles can be determined by measuring the ratio of the scattering intensity at the scattering vector at the lower limit of measurement of the measuring device and the scattering vector at which a peak corresponding to the order is observed using small-angle X-ray scattering, and as a result, the dispersion state in the dispersion medium can be predicted.

[0015] The scattering intensity (I) indicates the charge of the silica particles in the additive-containing silica sol. The larger the charge, the lower the I ０ ) region, the scattering intensity is found to decrease. ｍａｘ ) / (I ０ The smaller the charge of the silica particles, the smaller the charge of the silica particles. ｍａｘ ) / (I ０ In the present invention, the larger the charge of the silica particles, the larger the charge of the silica particles. ｍａｘ ) / (I ０ ) ratio of the silica sol before adding the additive ｍａｘ ) / (I ０It has been found that the stability of the silica sol is high when the ratio of the total weight of the silica sol to the total weight of the silica sol is reduced in the range of 0.1 to 4.8. The dispersion stability is particularly high when the dispersion medium is an aqueous medium having a pH of 1 to 10, or a pH of 1 to 6, or a pH of 8 to 10, or salt water having a salt concentration of 0.1 to 4.0 mass%, or an organic solvent.

[0016] The additive-containing silica sol (I) ｍａｘ ) / (I ０ of silica sol after adding additives from the ratio (I ｍａｘ ) / (I ０ ) ratio [(I Ｂ ｍａｘ ) / (I Ｂ ０ )-(I Ａ ｍａｘ ) / (I Ａ ０ ) can be set in the range of 0.1 to 4.8, or 0.2 to 4.4, or 0.8 to 4.4, or 1.7 to 4.4 [provided that (I ｍａｘ ) / (I ０ ) ratio is 1 or more (corresponding to the above formula (3))].

[0017] The silica sol used in the present invention has an average particle size of 5 to 200 nm, 5 to 150 nm, 5 to 100 nm, 5 to 80 nm, or 5 to 50 nm as measured by dynamic light scattering (DLS), and an average primary particle size of 5 to 200 nm, 5 to 150 nm, 5 to 100 nm, 5 to 80 nm, or 5 to 50 nm as measured by BET, Sears, or transmission electron microscope observation. The average primary particle size can be measured by BET, Sears, or transmission electron microscope observation.

[0018] The silica sol of the present invention has a solids content of 0.1 to 60% by mass, or 1 to 55% by mass, or 10 to 55% by mass. Here, the solids content refers to all components of the silica sol excluding the dispersion medium component. By setting the scattering intensity ratio as described above, for example, the haze value of a silica sol having a dispersion medium of salt water with a salt concentration of 4% by mass and a silica particle concentration of 0.1% by mass after storage at 20°C for 24 hours from the time of production can be lowered compared to the haze value of a silica sol before the addition of additives after storage at 20°C for 24 hours from the time of production. The additive-containing silica sol of the present invention preferably has a haze value (elapsed haze value) of 0 to 50, 0 to 30, 0 to 10, 0 to 5, 0 to 4, or 0 to 3 after storage at 20°C for 24 hours from the time of production using salt water with a salt concentration of 4% by mass as a dispersion medium and a silica particle concentration of 0.1% by mass. By making the silica sol fall within the above range, the silica particles contained in the silica sol are less likely to aggregate when dispersed in salt water or an organic solvent, and the silica sol can be used as a transparent dispersion liquid in which the dispersed state of the silica particles is maintained.

[0019] Furthermore, for the particle size measured by dynamic light scattering for a silica sol having a silica particle concentration of 0.1% by mass and using saltwater with a salt concentration of 4% by mass as a dispersion medium, the ratio of the particle size measured by dynamic light scattering after 24 hours of storage at 20°C to the particle size measured by dynamic light scattering at the time of production can be lower than the ratio of the particle size measured by dynamic light scattering for a silica sol before the addition of an additive to the particle size measured by dynamic light scattering at the time of production after 24 hours of storage at 20°C. Preferably, the additive-containing silica sol of the present invention uses saltwater with a salt concentration of 4% by mass as a dispersion medium and using a silica particle concentration of 0.1% by mass, and the particle size measured by dynamic light scattering for a silica sol after 24 hours of storage (elapsed DLS diameter) relative to the initial value (initial DLS diameter) within 12 hours of production (DLS change) is in the range of 0.5 to 5, 0.5 to 4, 0.5 to 3, 0.5 to 2, 0.5 to 1.8, 0.5 to 1.5, 0.8 to 4, or 0.8 to 1.8. By making the silica sol fall within the above range, the silica particles contained in the silica sol are less likely to aggregate when dispersed in salt water or an organic solvent, and therefore the silica sol can be used in a state where the number of silica particles is large and the specific surface area is high.

[0020] Examples of silica sols that can be used in the present invention include: 1) silica sols obtained by heating water glass as a raw material after removing alkali metal ions by cation exchange; 2) silica sols obtained by condensing a silane hydrolyzate obtained by hydrolyzing a hydrolyzable silane compound; 3) silica sols obtained by dispersing in a medium gas-phase fumed silica obtained by hydrolyzing a gasified product of silane tetrachloride with hydrogen and oxygen; and 4) silica sols obtained by reacting an aqueous alkali silicate solution with an acid, washing the precipitate, and then redispersing in an aqueous medium precipitated silica.

[0021] The silica sol of the present invention may contain an antioxidant as an additive, and may also contain a hydrolyzable silane, a sugar, an organic acid or a salt thereof, a sulfite, a thiocyanate, a mercapto organic acid or a salt thereof, a surfactant, or a polyhydroxy compound as an additive.

[0022] The hydrolyzable silane is added to the silica sol, and a part of it is coated on the surface of the silica particles, and a part of it exists as a hydrolyzate in the medium or on the surface of the silica particles. In the present invention, both may exist in a mixed state.

[0023] The hydrolyzable silane used in the present invention can have a structure of general formula (1). (In formula (1), R １ are organic groups having a cationic functional group or anionic functional group, and are bonded to a silicon atom by a Si—C bond, and R ２ represents an alkoxy group, an acyloxy group, or a halogen atom, and a represents an integer of 1 to 3.

[0024] The organic group having a cationic group is an organic group having an amino group, and examples of the amino group include a primary amino group, a secondary amino group, and a tertiary amino group. Examples of these organic groups having a cationic group include an N-2-(aminoethyl)-3-aminopropyl group, a 3-aminopropyl group, an N-(1,3-dimethyl-butylidene)propyl group, an N-phenyl-3-aminopropyl group, and a 3-ureidopropyl group. Examples of these silane compounds include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and 3-ureidopropyltrialkoxysilane.

[0025] Examples of organic groups having an anionic group include organic groups having a 2-(3,4-epoxycyclohexyl)ethyl group, a 3-glycidoxypropyl group, a propylsuccinic anhydride group, etc. Examples of these silane compounds include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and 3-trimethoxysilylpropylsuccinic anhydride.

[0026] The sugars used in the present invention include monosaccharides and polysaccharides, and examples of monosaccharides include triose, tetrose, pentose, hexose, heptose, arabinose, and glucose, and examples of polysaccharides include disaccharides, trisaccharides, and tetrasaccharides. Among these, examples of monosaccharides include arabinose and glucose, and further include sorbitol obtained by catalytic reduction of glucose.

[0027] The organic acid or its salt used in the present invention is an organic acid or its salt having a carboxy group or a sulfonic acid group, and an organic acid or its salt having a carboxy group is particularly preferred. These organic acid salts are salts of alkali metals such as sodium and potassium, or ammonium salts. They may further have a hydroxy group or a thiol group as an antioxidant functional group. Examples of organic acids include citric acid, acetic acid, malic acid, gluconic acid, lactic acid, succinic acid, tartaric acid, butyric acid, fumaric acid, propionic acid, formic acid, and thioglycolic acid. Hydroxycarboxylic acids are particularly preferred, including citric acid, malic acid, lactic acid, tartaric acid, and thioglycolic acid.

[0028] The sulfite salt used in the present invention is pyrosulfite salt, which has antioxidant properties. Examples of the salt include sodium salt, potassium salt, and ammonium salt.

[0029] The thiocyanate used in the present invention may be sodium thiocyanate.

[0030] The mercapto organic acid or its salt used in the present invention may be a mercaptoacetic acid salt or an ammonium salt thereof.

[0031] The surfactant used in the present invention may be an anionic surfactant, a cationic surfactant, a nonionic surfactant, or an amphoteric surfactant.

[0032] The surfactant is at least one surfactant selected from the group consisting of anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants, and surfactants containing at least anionic surfactants, nonionic surfactants, or both can be used.

[0033] Examples of anionic surfactants include sodium and potassium salts of fatty acids, alkylbenzenesulfonates, higher alcohol sulfates, polyoxyethylene alkyl ether sulfates, α-sulfofatty acid esters, α-olefinsulfonates, monoalkyl phosphates, and alkanesulfonates.

[0034] The alkylbenzene sulfonate has, for example, a sodium ion, a potassium ion, or a lithium ion as a counter ion. Specific examples of the alkylbenzene sulfonate include sodium C10 to C16 alkylbenzene sulfonate, potassium C10 to C16 alkylbenzene sulfonate, and sodium alkylnaphthalene sulfonate.

[0035] Examples of higher alcohol sulfates include sodium dodecyl sulfate (sodium lauryl sulfate) having 12 carbon atoms, triethanolamine lauryl sulfate, and triethanolammonium lauryl sulfate.

[0036] Examples of polyoxyethylene alkyl ether sulfates include polyoxyethylene styrenated phenyl ether sodium sulfate, polyoxyethylene styrenated phenyl ether ammonium sulfate, polyoxyethylene decyl ether sodium sulfate, polyoxyethylene decyl ether ammonium sulfate, polyoxyethylene lauryl ether sodium sulfate, polyoxyethylene lauryl ether ammonium sulfate, polyoxyethylene tridecyl ether sodium sulfate, and polyoxyethylene oleyl cetyl ether sodium sulfate.

[0037] Examples of the α-olefin sulfonate include sodium α-olefin sulfonate.

[0038] Examples of alkanesulfonates include sodium 2-ethylhexyl sulfate.

[0039] Examples of cationic surfactants include alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, and amine salt-based agents.

[0040] Alkyltrimethylammonium salts are quaternary ammonium salts, and have, for example, chloride ions or bromide ions as counter ions. Specific examples of the alkyltrimethylammonium salts include dodecyltrimethylammonium chloride, cetyltrimethylammonium chloride, coconut alkyltrimethylammonium chloride, and alkyl(C16-18)trimethylammonium chloride.

[0041] The dialkyldimethylammonium salt has two lipophilic main chains and two methyl groups, and examples thereof include didecyldimethylammonium chloride, dicoconut alkyldimethylammonium chloride, dihydrogenated tallow alkyldimethylammonium chloride, and dialkyl (C14-18) dimethylammonium chloride.

[0042] Alkyldimethylbenzylammonium salts are quaternary ammonium salts (benzalkonium chloride) having one lipophilic main chain, two methyl groups, and a benzyl group, and examples thereof include alkyl(C8-18)dimethylbenzylammonium chloride.

[0043] Amine salt agents are those in which the hydrogen atoms of ammonia are substituted with one or more hydrocarbon groups, and examples thereof include N-methylbishydroxyethylamine fatty acid ester hydrochloride.

[0044] Examples of amphoteric surfactants include N-alkyl-β-alanine-type alkylamino fatty acid salts, alkylcarboxybetaine-type alkylbetaines, and N,N-dimethyldodecylamine oxide-type alkylamine oxides, such as lauryl betaine, stearyl betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, and lauryl dimethylamine oxide.

[0045] The nonionic surfactant is selected from the group consisting of polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, alkyl glucosides, polyoxyethylene fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and fatty acid alkanolamides.

[0046] Examples of polyoxyethylene alkyl ethers include polyoxyethylene dodecyl ether (polyoxyethylene lauryl ether), polyoxyalkylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyalkylene tridecyl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene behenyl ether, polyoxyethylene-2-ethylhexyl ether, and polyoxyethylene isodecyl ether.

[0047] Examples of polyoxyethylene alkylphenyl ethers include polyoxyethylene styrenated phenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene distyrenated phenyl ether, and polyoxyethylene tribenzyl phenyl ether.

[0048] Examples of alkyl glucosides include decyl glucoside and lauryl glucoside.

[0049] Examples of polyoxyethylene fatty acid esters include polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, polyethylene glycol distearate, polyethylene glycol dioleate, and polypropylene glycol dioleate.

[0050] Examples of sucrose fatty acid esters include sucrose palmitate, sucrose stearate, sucrose laurate, sucrose erucate, and sucrose oleate.

[0051] Examples of sorbitan fatty acid esters include sorbitan monocaprylate, sorbitan monolaurate, sorbitan monomyristate, sorbitan monopalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan monosesquioleate, and ethylene oxide adducts thereof.

[0052] Examples of polyoxyethylene sorbitan fatty acid esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan triisostearate.

[0053] Examples of fatty acid alkanolamides include coconut oil fatty acid diethanolamide, beef tallow fatty acid diethanolamide, lauric acid diethanolamide, and oleic acid diethanolamide.

[0054] Furthermore, polyoxyalkyl ethers or polyoxyalkyl glycols such as polyoxyethylene polyoxypropylene glycol, polyoxyethylene fatty acid esters, polyoxyethylene hydrogenated castor oil ether, sorbitan fatty acid ester alkyl ether, alkyl polyglucosides, and the like can also be used.

[0055] In the present invention, polyhydroxy compounds can be used as additives. Polyhydroxy compounds exhibit antioxidant properties. Polyhydroxy compounds have a structure in which multiple hydroxyl groups are bonded to a linear or cyclic hydrocarbon structure, and can contain diols, triols, or their repeating units. A typical example is ascorbic acid, and its derivatives, such as glyceryl ascorbic acid, can also be used.

[0056] In the present invention, the dispersion medium for the silica sol containing an additive is preferably a highly ionic dispersion medium or a highly polar organic solvent. For example, an aqueous medium having a pH of 1 to 10, or a pH of 1 to 6, or a pH of 8 to 10, or salt water having a salt concentration of 0.1 to 4.0% by mass, such as seawater, is also suitable. Organic solvents, particularly organic solvents with high polarity, are also suitable.

[0057] The polar organic solvent may be a protic solvent or an aprotic solvent. A protic polar solvent is a polar solvent that readily donates a proton and has a high dielectric constant. An aprotic polar organic solvent has a dielectric constant. Examples of polar organic solvents include organic solvents such as dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, methanol, ethanol, and acetic acid.

[0058] In the present invention, the additive-containing silica sol of the present invention can be produced by a method including a step of incorporating an additive into a silica sol and adjusting the scattering intensity (I) relative to the scattering vector (q) of the additive-containing silica sol, as determined by a small-angle scattering method using X-rays, so that the following formulas (2) and (3) are satisfied: Here, in the formula (2) and the formula (3), I Ｂ ０ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol before adding the additive is 3.5 mass % －１ represents the scattering intensity when is 0.05, and I Ｂ ｍａｘ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol before adding the additive is 3.5 mass % －１ represents the scattering intensity at its maximum value, and I Ａ ０ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol after adding the additive is 3.5 mass% －１ represents the scattering intensity when is 0.05, and I Ａ ｍａｘ is the scattering vector (q) nm of the silica sol after adding the additive when the silica particle concentration is 3.5 mass% －１represents the scattering intensity at which the value is maximized. By including a step of incorporating an additive into the silica sol and adjusting the dispersion so that the above formulas (2) and (3) are satisfied, the additive-containing silica particles can be stably dispersed in the dispersion medium. The additive content may be the set value in the aqueous medium of the silica sol, or may be the value after changing the solvent to an aqueous medium of pH 1 to 10, for example, pH 1 to 6, an aqueous medium of pH 8 to 10, or salt water with a salt concentration of 0.1 to 4.0 mass%, or an organic solvent. The additive-containing silica sol of the present invention can be used in adhesives, release agents, semiconductor encapsulants, LED encapsulants, paints, film internal additives, hard coating agents, photoresists, printing inks, detergents, cleaners, additives for various resins, insulating compositions, rust inhibitors, lubricants, metalworking oils, film coating agents, stripping agents, well treatment agents, etc.

[0059] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. In the following examples and comparative examples, the apparatus and conditions used for sample preparation and physical property analysis are as follows.

[0060] (Small-angle X-ray scattering device) A NANO-Viewer (trade name) manufactured by Rigaku Corporation was used. (DLS average particle size (dynamic light scattering particle size)) A Zetasizer Nano (trade name) dynamic light scattering particle size measuring device (manufactured by the Malvern Division of Spectris Co., Ltd.) was used. (pH measurement) A pH meter (manufactured by DKK Toa Corporation) was used. (HAZE value) A NDH5000 (trade name) haze meter (manufactured by Nippon Denshoku Industries Co., Ltd.) was used. The haze value is a value indicating the haze or turbidity of silica sol when irradiated with visible light, and is expressed as the ratio of the total light transmittance T.T., which includes all parallel components P.T. and diffuse components, to the diffuse transmittance D.I.F. excluding the parallel components. HAZE value = D.I.F / T.T. T×100 (SAXS measurement conditions for small-angle X-ray scattering spectrum) A Cu-Kα ray was used as the X-ray source. X-rays were irradiated onto a sample sealed in a capillary, and the scattered X-rays were detected using a two-dimensional detector (trade name: PILATUS 200k, manufactured by Dektris). The distance from the sample to the detector was 1200 mm. The obtained two-dimensional image was converted to one-dimensional data using a 2DP (manufactured by Rigaku Corporation), and the scattering vector (q) and scattering intensity (I) were extracted. (Salt tolerance evaluation) After placing a stirrer in a 200 ml polystyrene bottle, each of the chemical solutions produced in Examples 1 to 13 or Comparative Examples 1 to 3 was diluted with salt water (artificial seawater) and pure water to a silica concentration of 0.1% by mass. For example, in Example 4, 0.56 g of the chemical solution was added and stirred with a magnetic stirrer. While stirring with a magnetic stirrer, 10.56 g of pure water and 88.89 g of brine with a salt concentration of 4.5% by mass were added and stirred for 1 hour. This was used as a brine test sample (saltwater evaluation sample) to evaluate the heat resistance and salt resistance of the chemical solution at a salt concentration of 4% by mass. The main component of the salt was sodium chloride, and it also contained calcium chloride, magnesium chloride, magnesium sulfate, sodium bicarbonate, etc. 100 g of the brine test sample was placed in a 200 ml sealable polystyrene container, sealed, and then the polystyrene container was left at 20°C for 24 hours. After that, the appearance of the brine test sample, the DLS average particle size of the aqueous silica sol (silica particles) in the sample, and the HAZE value were evaluated. For example, in Example 12, 0.97 g of chemical solution was added and stirred with a magnetic stirrer.While stirring with a magnetic stirrer, 10.14 g of pure water and 88.89 g of brine with a salt concentration of 4.5% by mass were added and stirred for 1 hour. This was used as a brine test sample (saltwater evaluation sample) to evaluate the heat resistance and salt resistance of the chemical solution at a salt concentration of 4% by mass. The main component of the salt was sodium chloride. 100 g of the brine test sample was placed in a 200 ml sealable polystyrene container, sealed, and then the polystyrene container was left to stand at 20°C for 24 hours. After that, the appearance of the brine test sample, the DLS average particle size of the aqueous silica sol (silica particles) in the sample, and the HAZE value were evaluated. For example, in Example 13, 0.26 g of chemical solution was added and stirred with a magnetic stirrer. While stirring with a magnetic stirrer, 10.85 g of pure water and 88.89 g of brine with a salt concentration of 4.5% by mass were added and stirred for 1 hour. This was used as a brine test sample (saltwater evaluation sample) to evaluate the heat resistance and salt resistance of a chemical solution at a salt concentration of 4% by mass. The main component of the salt was sodium chloride. 100 g of the brine test sample was placed in a 200 ml sealable polystyrene container, sealed, and then the polystyrene container was left at 20°C for 24 hours. The appearance of the brine test sample, the DLS average particle size of the aqueous silica sol (silica particles) in the sample, and the HAZE value were evaluated. A silica sol (1) manufactured by Nissan Chemical Industries, Ltd. (pH 2.6, silica concentration 20.0% by mass, average primary particle size by BET method 12.0 nm, average particle size by DLS method 17 nm) was prepared. A silica sol (2) manufactured by Nissan Chemical Industries, Ltd. (pH 2.7, silica concentration 10.5% by mass, average primary particle size by Sears method 5.0 nm, average particle size by DLS method 9 nm) was prepared. As aqueous silica sol (3), a silica sol manufactured by Nissan Chemical Industries, Ltd. (pH 2.4, silica concentration 40.5 mass %, average primary particle diameter by BET method 22.0 nm, average particle diameter by DLS method 35 nm) was prepared.

[0061] Example 1 A 2,000 mL glass recovery flask was charged with 1,200 g of aqueous silica sol (1) and a magnetic stirrer. While stirring with the magnetic stirrer, 191.0 g of 3-glycidoxypropyltrimethoxysilane (Dynasylan (trade name) GLYMO, manufactured by Evonik) was added so that the mass ratio of the silane compound to the silica (colloidal silica particles) in the aqueous silica sol was 0.80. A cooling tube through which tap water was flowed was then placed on top of the recovery flask, and the aqueous sol was heated to 60°C while refluxing. The temperature was maintained at 60°C for 4 hours, after which it was cooled. After cooling to room temperature, the aqueous sol was removed. This aqueous silica sol was placed in a crucible and heated on a hot plate at 100°C to remove the solvent. It was then fired in an electric furnace at 1,000°C for 30 minutes, and the resulting firing residue was calculated as the silica solids content. There was obtained 1,391.0 g of an aqueous silica sol of Example 1 that had been surface-treated with a silane compound, having a mass ratio of the silane compound to the silica in the aqueous silica sol of 0.80, a silica solid content of 21.2 mass%, a pH of 3.1, an electrical conductivity of 353 μS / cm, and a DLS average particle size of 23.2 nm.

[0062] Example 2 A stirring bar was placed in a 120 mL polystyrene bottle, and 101.0 g of the aqueous silica sol produced in Example 1 was added while stirring with a magnetic stirrer. 15 g of pure water was added, followed by 0.96 g of anionic surfactant sodium α-olefin sulfonate (Neogen (trade name) AO-90, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., active ingredient 100% by mass) and stirring until completely dissolved. 0.36 g of anionic surfactant sodium dodecyl sulfate (Shinoline (trade name) 90TK-T, manufactured by New Japan Chemical Co., Ltd., active ingredient 97% by mass) was then added and stirring until completely dissolved. 2.07 g of a nonionic surfactant polyoxyethylene styrenated phenyl ether with an HLB of 14.3 (Noigen (trade name) EA-157, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., active ingredient 100% by mass) diluted with pure water to 70% by mass of active ingredient was then added to produce the medicinal solution of Example 2. At this time, the mass ratio of the anionic surfactant to the silica solid content of the aqueous silica sol was 0.03, and the mass ratio of the nonionic surfactant to the silica solid content of the aqueous silica sol was 0.07.

[0063] Example 3 1,000 g of aqueous silica sol (1) and a magnetic stirrer were placed in a 2,000 mL glass recovery flask. While stirring with the magnetic stirrer, 121.36 g of lactic acid (Kanto Chemical Co., Ltd., active ingredient 85-92% by mass) was added, followed by 149.12 g of 4-aminopropyltriethoxysilane (Shin-Etsu Chemical Co., Ltd., trade name KBE-903). Subsequently, a cooling tube filled with tap water was placed on top of the recovery flask, and the aqueous sol was heated to 60°C under reflux, maintained at 60°C for 4 hours, and then cooled. After cooling to room temperature, the aqueous sol was removed. 1,270.48 g of aqueous silica sol of Example 3, surface-treated with a silane compound, was obtained, having a silica solids content of 19.36% by mass, a pH of 3.93, an electrical conductivity of 697 μS / cm, and a DLS average particle size of 21.79 nm.

[0064] (Example 4) A stirring bar was placed in a 120 mL polystyrene bottle, and 9.15 g of pure water and 87.76 g of aqueous silica sol (1) were added and stirred with a magnetic stirrer. Subsequently, while stirring with the magnetic stirrer, 3.09 g of ascorbic acid (manufactured by Junsei Chemical Co., Ltd., active ingredient 97% by mass) was added and stirred until completely dissolved, thereby producing a medicinal solution of Example 4.

[0065] (Example 5) A stirring bar was placed in a 120 mL polystyrene bottle, and 9.15 g of pure water and 87.76 g of aqueous silica sol (1) were added and stirred with a magnetic stirrer. Subsequently, while stirring with the magnetic stirrer, 3.09 g of sodium pyrosulfite (FUJIFILM, manufactured by Wako Pure Chemical Industries, Ltd., active ingredient 97% by mass) was added and stirred until completely dissolved, thereby producing a medicinal solution of Example 5.

[0066] (Example 6) A stirring bar was placed in a 120 mL polystyrene bottle, and 6.24 g of pure water and 87.76 g of aqueous silica sol (1) were added and stirred with a magnetic stirrer. Subsequently, while stirring with the magnetic stirrer, 5.99 g of gluconic acid (FUJIFILM, manufactured by Wako Pure Chemical Industries, Ltd., active ingredient 50% by mass) was added and stirred until completely dissolved, thereby producing a medicinal solution of Example 6.

[0067] (Example 7) A stirring bar was placed in a 120 mL polystyrene bottle, and 9.15 g of pure water and 87.76 g of aqueous silica sol (1) were added and stirred with a magnetic stirrer. Subsequently, while stirring with the magnetic stirrer, 3.09 g of sodium dodecyl sulfate (Shinoline (trade name) 90TK-T, active ingredient 97% by mass, manufactured by New Japan Chemical Co., Ltd.) was added and stirred until completely dissolved, thereby producing the medicinal solution of Example 7.

[0068] (Example 8) A stirring bar was placed in a 120 mL polystyrene bottle, and 9.24 g of pure water and 87.76 g of aqueous silica sol (1) were added and stirred with a magnetic stirrer. Subsequently, while stirring with the magnetic stirrer, 2.99 g of glucose (manufactured by Nihon Shokuhin Kako Co., Ltd., trade name Nisshoku Anhydrous Crystalline Glucose #300, active ingredient 100% by mass) was added and stirred until completely dissolved, thereby producing a medicinal solution of Example 8.

[0069] (Example 9) A stirring bar was placed in a 120 mL polystyrene bottle, and 9.15 g of pure water and 87.76 g of aqueous silica sol (1) were added and stirred with a magnetic stirrer. Subsequently, while stirring with the magnetic stirrer, 3.09 g of sodium sulfite (FUJIFILM, manufactured by Wako Pure Chemical Industries, Ltd., active ingredient 97% by mass) was added and stirred until completely dissolved, thereby producing a medicinal solution of Example 9.

[0070] (Example 10) A stirring bar was placed in a 120 mL polystyrene bottle, and 9.24 g of pure water and 87.76 g of aqueous silica sol (1) were added and stirred with a magnetic stirrer. Subsequently, while stirring with the magnetic stirrer, 2.99 g of sodium thiocyanate (FUJIFILM, manufactured by Wako Pure Chemical Industries, Ltd., active ingredient 100% by mass) was added and stirred until completely dissolved, thereby producing a medicinal solution of Example 10.

[0071] (Example 11) A stirring bar was placed in a 120 mL polystyrene bottle, and 6.24 g of pure water and 87.76 g of aqueous silica sol (1) were added and stirred with a magnetic stirrer. Subsequently, while stirring with the magnetic stirrer, 5.99 g of ammonium mercaptoacetate (FUJIFILM, manufactured by Wako Pure Chemical Industries, Ltd., active ingredient 50% by mass) was added and stirred until completely dissolved, thereby producing a chemical solution of Example 11.

[0072] (Example 12) A stirring bar was placed in a 120 mL polystyrene bottle, and 98.23 g of aqueous silica sol (2) was added and stirred with a magnetic stirrer. Subsequently, while stirring with the magnetic stirrer, 1.77 g of ascorbic acid (manufactured by Junsei Chemical Co., Ltd., active ingredient 97% by mass) was added and stirred until completely dissolved, thereby producing a medicinal solution of Example 12.

[0073] (Example 13) A stirring bar was placed in a 120 mL polystyrene bottle, and 93.5 g of aqueous silica sol (3) was added and stirred with a magnetic stirrer. Subsequently, while stirring with the magnetic stirrer, 6.50 g of ascorbic acid (manufactured by Junsei Chemical Co., Ltd., active ingredient 97% by mass) was added and stirred until completely dissolved, thereby producing a medicinal solution of Example 13.

[0074] Comparative Example 1 Aqueous silica sol (1) was used.

[0075] Comparative Example 2 Aqueous silica sol (2) was used.

[0076] Comparative Example 3 Aqueous silica sol (3) was used.

[0077] (Evaluation of Silica Sol) Examples 1 to 13 and Comparative Examples 1 to 3 Ａ ０ , I Ａ ｍａｘ , I Ｂ ０ and I Ｂ ｍａｘ are listed in Tables 1 to 4. Ｂ ０ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol before adding the additive is 3.5 mass % －１ represents the scattering intensity when is 0.05, and I Ｂ ｍａｘ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol before adding the additive is 3.5 mass % －１ represents the scattering intensity at its maximum value, and I Ａ ０ is the scattering vector (q) nm of the silica sol when the silica particle concentration in the silica sol after adding the additive is 3.5 mass%－１ represents the scattering intensity when is 0.05, and I Ａ ｍａｘ is the scattering vector (q) nm of the silica sol after adding the additive when the silica particle concentration is 3.5 mass% －１ represents the scattering intensity at which the maximum value is reached. Ｂ ｍａｘ ) / (I Ｂ ０ ) ratio (I Ａ ｍａｘ ) / (I Ａ ０ ) ratio is subtracted from the value shown in Tables 1 to 3. FIG. 1 shows the results of small-angle X-ray scattering measurement of the silica sols obtained in Examples 1, 10, and 11. The horizontal axis represents the scattering vector (q), and the vertical axis represents the scattering intensity (I). FIG. 2 is an enlarged view thereof. FIG. 3 shows the results of small-angle X-ray scattering measurement of the silica sols obtained in Comparative Examples 1, 2, and 3. The horizontal axis represents the scattering vector (q), and the vertical axis represents the scattering intensity (I). FIG. 4 is an enlarged view thereof. The salt resistance of the samples was evaluated by the haze value after 24 hours of storage at 20°C, and the change over time was shown in terms of particle size (DLS change) values ​​measured by dynamic light scattering. That is, for the haze value of a silica sol having a silica particle concentration of 0.1% by mass and a saltwater with a salt concentration of 4% by mass as the dispersion medium, the haze value (elapsed haze value) after 24 hours of storage at 20°C from the time of production is shown in the table below. Furthermore, for the particle diameter of silica sol with a silica particle concentration of 0.1% by mass and a salt water with a salt concentration of 4% by mass as a dispersion medium, the following table shows the DLS change (the ratio of the initial value (initial DLS diameter) within 12 hours of production to the value after 24 hours of storage (elapsed DLS diameter). The unit of scattering intensity (I) is (a.u.).

[0078]

[0079]

[0080]

[0081]

[0082] The additive-containing silica sols of Examples 1 to 11, by satisfying formulas (2) and (3), had lower elapsed haze values ​​and smaller DLS changes than the additive-free silica sol of Comparative Example 1. Similarly, by satisfying formulas (2) and (3), the additive-containing silica sol of Example 12 had lower elapsed haze values ​​and smaller DLS changes than the additive-free silica sol of Comparative Example 2, and the additive-containing silica sol of Example 13 had lower elapsed haze values ​​and smaller DLS changes than the additive-free silica sol of Comparative Example 3.

[0083] A stable silica sol can be obtained by satisfying specific conditions for the scattering intensity (I) of a specific scattering vector of an additive-containing silica sol determined by a small-angle scattering method using X-rays. The silica sol is highly stable, particularly in dispersion media having a pH of 1 to 10, for example, an aqueous medium having a pH of 1 to 6, an aqueous medium having a pH of 8 to 10, a high-electrolyte medium such as brine having a salt concentration of 0.1 to 4.0 mass%, and a polar organic solvent, and can be applied to fields that use such dispersion media.

Claims

1. An additive-containing silica sol characterized in that the scattering intensity (I) with respect to the scattering vector (q) of the additive-containing silica sol, determined by small-angle scattering using X-rays, satisfies the following equations (2) and (3). [Math 1] Here, in equations (2) and (3), I Ｂ ０ This is the scattering vector (q) nm of the silica sol before the addition of additives, when the silica particle concentration is 3.5% by mass. －１ This represents the scattering intensity when the value is 0.

05. I Ｂ ｍａｘ This is the scattering vector (q) nm of the silica sol before the addition of additives, when the silica particle concentration is 3.5% by mass. －１ This represents the scattering intensity at which the value is maximum. I Ａ ０ represents the scattering vector (q) nm of the silica sol at a silica particle concentration of 3.5% by mass in the silica sol after containing the additive －１ when it is 0.05, and represents the scattering intensity I Ａ ｍａｘ This is the scattering vector (q) nm of the silica sol after adding the additive, when the silica particle concentration is 3.5% by mass. －１ This represents the scattering intensity at which the value is maximum.

2. The silica sol according to claim 1, wherein the haze value of a silica sol with a silica particle concentration of 0.1% by mass, dispersed in a saline solution with a salt concentration of 4% by mass as the dispersion medium, is lower after storage at 20°C for 24 hours from the time of manufacture compared to the haze value of the silica sol before additive inclusion after storage at 20°C for 24 hours from the time of manufacture.

3. The particle size of a silica sol with a silica particle concentration of 0.1% by mass, dispersed in a 4% by mass saline solution, was measured by dynamic light scattering. The ratio of the particle size measured by dynamic light scattering after 24 hours of storage at 20°C to the particle size measured by dynamic light scattering at the time of manufacture was found to be the same for the silica sol before additive inclusion. The silica sol according to claim 1, wherein the ratio of the particle size measured by dynamic light scattering after storage at 20°C for 24 hours to the particle size measured by dynamic light scattering during manufacturing is lower.

4. The silica sol according to claim 1, wherein the additive is an antioxidant.

5. The silica sol according to claim 1, wherein the additive is a hydrolyzable silane, sugar, organic acid or salt thereof, sulfite, thiocyanate, mercapto organic acid or salt thereof, surfactant, or polyhydroxy compound.

6. Hydrolyzable silanes are given by the following formula (1): 【Chemistry 1】 (In formula (1), R １ Each of these is an organic group having a cationic functional group or an organic group having an anionic functional group and is bonded to a silicon atom by a Si-C bond, R ２ The silica sol according to claim 5, where each of represents an alkoxy group, an acyloxy group, or a halogen atom, and a represents an integer from 1 to 3.

7. The silica sol according to claim 6, wherein the cationic functional group is an amino group.

8. The silica sol according to claim 6, wherein the anionic functional group is a glycidoxy group.

9. The silica sol according to claim 5, wherein the sugar is sorbitol, glucose, or arabinose.

10. The silica sol according to claim 5, wherein the organic acid or salt thereof is gluconic acid, lactic acid, or thioglycolic acid, or a salt thereof.

11. The silica sol according to claim 5, wherein the sulfite is a pyrosulfite.

12. The silica sol according to claim 5, wherein the thiocyanate is sodium thiocyanate.

13. The silica sol according to claim 5, wherein the mercapto organic acid or a salt thereof is mercaptoacetic acid or an ammonium salt thereof.

14. The silica sol according to claim 5, wherein the surfactant is at least one surfactant selected from the group consisting of anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants, and the surfactant contains at least anionic surfactants, nonionic surfactants, or both.

15. The silica sol according to claim 5, wherein the polyhydroxy compound is ascorbic acid.

16. The silica sol according to claim 1, wherein the dispersion medium for the silica sol is an aqueous medium with a pH of 1 to 10, saline solution with a salt concentration of 0.1 to 4.0% by mass, or an organic solvent.

17. A method for producing an additive-containing silica sol according to any one of claims 1 to 16, wherein the silica sol contains an additive, and by small-angle scattering using X-rays A method characterized by including a step of adjusting the scattering intensity (I) of the required additive-containing silica sol with respect to the scattering vector (q) so that it satisfies the following equations (2) and (3). [Math 2] Here, in equations (2) and (3), I Ｂ ０ This is the scattering vector (q) nm of the silica sol before the addition of additives, when the silica particle concentration is 3.5% by mass. －１ This represents the scattering intensity when the value is 0.

05. I Ｂ ｍａｘ This is the scattering vector (q) nm of the silica sol before the addition of additives, when the silica particle concentration is 3.5% by mass. －１ This represents the scattering intensity at which the value is maximum. I Ａ ０ This is the scattering vector (q) nm of the silica sol after adding the additive, when the silica particle concentration is 3.5% by mass. －１ This represents the scattering intensity when the value is 0.

05. I Ａ ｍａｘ This is the scattering vector (q) nm of the silica sol after adding the additive, when the silica particle concentration is 3.5% by mass. －１ This represents the scattering intensity at which the value is maximum.

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