Highly concentrated and highly stable hollow silica organosol and method for producing the same

Abstract

To provide an organosol containing hollow silica particles, which contains hollow silica particles at a high concentration and has high dispersion stability in a medium. [Solution] A hollow silica organosol containing the following components (A) and (B), wherein the component (A) is contained in an amount of 20% by mass to 70% by mass relative to the total amount (100% by mass) of the organosol, and a method for producing the hollow silica organosol: Component (A): aluminum atom-containing hollow silica particles, wherein the amount of aluminum atoms present throughout the hollow silica particles is 120 to 50,000 ppm / SiO2 in terms of Al2O3 relative to the mass of the hollow silica particles, and the average particle diameter measured by dynamic light scattering is 20 to 150 nm; Component (B): A dispersion medium containing at least one of an organic solvent, a reactive monomer, and a polymer.

Description

[Technical Field]

[0001] The present invention relates to an organosol in which hollow silica particles containing aluminum atoms are dispersed, and more particularly to an organosol in which the hollow silica particles are stably dispersed at a high concentration, a method for producing the organosol, and a resin composition containing the organosol. [Background technology]

[0002] Silica sol is used in various fields as an abrasive, functional inorganic filler, etc. Although silica sol is stable and does not gel in the alkaline range, when alkaline silica sol is blended into a composition containing an organosilicon compound or resin as a binder, the alkaline condition tends to cause cloudiness and thickening. Furthermore, when preparing organosilica sol by solvent substitution, problems remain, such as gelation upon mixing with alcohol, etc. On the other hand, in the acidic range, the zeta potential of silica particles is small, resulting in small electrical repulsion, making silica sol unstable and prone to gelation. However, silica sol is often required in the acidic range, such as in acidic abrasives, raw materials for ceramic fibers, and chromium-based surface treatment agents.

[0003] One method known to improve the stability of silica sols in acidic regions is to modify the surfaces of silica particles with an aluminum compound. In this method, aluminosilicate sites are formed on the silica particle surfaces by reaction between aluminate ions derived from the aluminum compound and silanol groups on the silica particle surfaces. The aluminosilicate sites impart a negative charge to the silica particles, i.e., increase the negative zeta potential of the silica particles, thereby improving the dispersion stability of the silica particles in the dispersion medium. This method also improves the compatibility of silica particles with highly polar organic solvents and charged resins. For example, a method for producing an acidic silica sol has been disclosed (see Patent Document 1), in which an aqueous alkali aluminate solution is added to a dispersion of solid silica particles so that the Al2O3 / SiO2 molar ratio is greater than 0.0006 and less than 0.004, and the resulting silica sol is heated at 80 to 250°C and then subjected to cation exchange.

[0004] Furthermore, hollow silica particles have a silica outer shell and a space inside the shell, and because of these characteristics, they have properties such as a low refractive index, low thermal conductivity (thermal insulation), and electrical insulation. Hollow silica particles consist of a core corresponding to the hollow portion and an outer shell that forms the outside of the core. An aqueous dispersion of hollow silica particles can be obtained by forming a silica layer on the outside of a template particle in an aqueous medium and then removing the template particle. For example, a method has been disclosed in which a core-shell particle having an aluminosilicate shell is produced by reacting a silane compound and an aluminum precursor with a Si / Al molar ratio of 7 to 15 on a template core made of an organic polymer in the form of a micelle or reverse micelle, and then reacting this with a basic or acidic aqueous solution to simultaneously form pores in the shell (outer shell) and remove the core, followed by a hydrothermal reaction by heating at 160 to 200°C to produce a hollow silica sol with a high density shell (see Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-199515 [Patent Document 2] Korean Patent No. 10-1659709 Summary of the Invention [Problem to be solved by the invention]

[0006] In order to stabilize silica sol containing hollow silica particles with cavities inside the shell, the particles are modified from the outside with an aluminum compound (i.e., impregnated with the aluminum compound). The aluminum compound penetrates the shell, and the aluminum compound that remains outside the shell (impregnated) and the aluminum compound that reaches the inside of the shell (impregnated) each form aluminosilicate sites. The alkali metal present in the silica particles and derived from the alkali metal silicate, which is the raw material for the silica sol, is captured by the respective aluminosilicate sites. However, depending on the manufacturing, use, and storage conditions of the silica particles, the alkali metal encapsulated within the silica particles may be released over time, resulting in an increase in the pH of the system and the aforementioned instability. In the case of hollow silica particles, the alkali metal present in the aluminosilicate sites outside the shell can be removed during manufacturing by cation exchange or other methods, but it is difficult to remove the alkali metal present in the aluminosilicate sites inside the shell. Furthermore, since aluminosilicate may be generated even inside the silica particles, which is not originally involved in the dispersion stabilization of the silica particles, the amount of aluminum present in the aluminosilicate per silica particle increases, resulting in an increase in the amount of alkali metal present in the aluminosilicate sites. Moreover, the alkali metal may leak into the dispersion medium through the pores of the shell over time, which may cause an increase in the pH of the system and may impair the dimensional stability of the hollow silica particles and the storage stability of the silica sol.

[0007] On the other hand, when silica sol is applied in a wide variety of fields, for example, when it is mixed with a resin material to make a composite material, using a sol with a high silica particle concentration can be advantageous in terms of manufacturing, such as ease of handling and shortened curing and drying times. Furthermore, silica sol containing silica particles at a high concentration increases the amount of silica per unit volume, which is advantageous from the standpoints of transportation and storage. However, in general, high-concentration silica sols are prone to gelation and precipitation, making them difficult to store for long periods of time. In addition, they also tend to aggregate during the process of increasing the concentration, making their production itself difficult. [Means for solving the problem]

[0008] As a first aspect, the present invention provides: A hollow silica organosol containing the following components (A) and (B), wherein the component (A) is contained in an amount of 20% by mass to 70% by mass based on the total amount (100% by mass) of the organosol: Component (A): aluminum atom-containing hollow silica particles, the amount of aluminum atoms present throughout the hollow silica particles is 120 to 50,000 ppm / SiO2 in terms of Al2O3 relative to the mass of the hollow silica particles; hollow silica particles having an average particle size of 20 to 150 nm as measured by dynamic light scattering; Component (B): A dispersion medium containing at least one of an organic solvent, a reactive monomer, and a polymer. As a second aspect, the present invention relates to the hollow silica organosol according to the first aspect, which satisfies the following formula (N) in a thermal stability test 1 in which the hollow silica organosol is maintained at 50° C. for one week: Formula (N): 1.3≧(X 1w ) / (X0)≧0.7 where (X0) is the average particle size measured by dynamic light scattering before thermal stability test 1, and (X 1w ) indicates the average particle size determined by dynamic light scattering after thermal stability test 1. As a third aspect, the present invention relates to the hollow silica organosol according to the first aspect, which satisfies the following formula (O) and the following formula (P) in a thermal stability test 2 in which the hollow silica organosol is maintained at 50° C. for 4 weeks: Formula (O): 1.2≧(X 4w ) / (X0)≧0.8 where (X0) is the average particle size measured by dynamic light scattering before thermal stability test 2, and (X 4w ) indicates the average particle size measured by dynamic light scattering after thermal stability test 2, Formula (P): 1.2≧(V 4w ) / (V0)≧0.8 where (V0) indicates the viscosity measured at 25°C before the thermal stability test 2, and (V 4w ) indicates the viscosity measured at 25°C after heat stability test 2. As a fourth aspect, the present invention relates to the hollow silica organosol according to First Aspect 1, in which the (A) hollow silica particles satisfy the following (i) to (iv): (i) the thickness of the shell of the hollow silica particles is 3 to 8 nm; (ii) the number density of silanol groups on the surface of the hollow silica particles is 0.2 to 6.0 / nm 2 That is, (iii) the surface charge amount calculated per 1 g of the hollow silica particles is 20 μeq / g to 200 μeq / g; (iv) The hollow silica particles have a carbon content of 0.1% by mass to 10.0% by mass as determined by elemental analysis. As a fifth aspect, the present invention relates to the hollow silica organosol according to the first aspect, further comprising the following component (C): Component (C): At least one silane compound selected from the group consisting of compounds represented by the following formulas (1) and (2): [ka] (In formula (1), R 1 are groups bonded to a silicon atom, and each independently represent an alkyl group, a halogenated alkyl group, an alkenyl group, or an aryl group, or an organic group having an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxy group, a protected carboxy group, a carboxy group-generating group, an imide group, or a cyano group, and which are bonded to a silicon atom via a Si-C bond, or a combination of these groups; R 2 are groups or atoms bonded to the silicon atom, which independently represent an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom, or a combination of these groups or atoms; a represents an integer of 1 to 3; In formula (2), R 3 are groups bonded to a silicon atom, and each independently represent an alkyl group, a halogenated alkyl group, an alkenyl group, or an aryl group, or an organic group having an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxy group, a protected carboxy group, a carboxy group-generating group, an imide group, or a cyano group, and which are bonded to a silicon atom via a Si-C bond, or a combination of these groups; R 4are groups or atoms bonded to the silicon atom, which independently represent an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom, or a combination of these groups or atoms; Y is a group or atom bonded to the silicon atom and represents an alkylene group, an NH group, or an oxygen atom; b represents an integer of 1 to 3, and c represents an integer of 0 or 1. As a sixth aspect, the (A) hollow silica particles have a surface area of ​​1 nm 2 The hollow silica organosol according to a fifth aspect, wherein the particles are surfaces coated with the silane compound of component (C) or particles having the silane compound of component (C) bonded to the surface thereof, at a ratio of 0.1 to 10 particles per particle. As a seventh aspect, the present invention relates to the hollow silica organosol according to the first aspect, which further contains a basic compound. According to an eighth aspect, the present invention relates to the hollow silica organosol according to the first aspect, in which the organic solvent of the component (B) is selected from the group consisting of alcohols, ketones, ethers, esters, and amides. As a ninth aspect, the present invention relates to the hollow silica organosol according to the first aspect, in which the reactive monomer of the component (B) is at least one silane compound selected from the group consisting of a (meth)acrylic compound, a (meth)polyfunctional acrylate, an allyl compound, an isocyanate compound, an isothiocyanate compound, an epoxy compound, a diamine-containing compound, a diol-containing compound, a dicarboxylic acid-containing compound, a disulfonyl chloride-containing compound, a dithiol-containing compound, a disulfide-containing compound, a divinyl-containing compound, a diallyl-containing compound, styrene, a tetracarboxylic acid anhydride, a bismaleimide, a vinyl-containing compound, a lactone ring-containing compound, a lactide-containing compound, a fluorine-containing compound, a cyclic olefin-containing compound, ethylene, propylene, or compounds represented by the following formulas (1) and (2): [ka] (In formula (1), R 1are groups bonded to a silicon atom, and each independently represent an alkyl group, a halogenated alkyl group, an alkenyl group, or an aryl group, or an organic group having an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxy group, a protected carboxy group, a carboxy group-generating group, an imide group, or a cyano group, and which are bonded to a silicon atom via a Si-C bond, or a combination of these groups; R 2 are groups or atoms bonded to the silicon atom, which independently represent an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom, or a combination of these groups or atoms; a represents an integer of 1 to 3; In formula (2), R 3 are groups bonded to a silicon atom, and each independently represent an alkyl group, a halogenated alkyl group, an alkenyl group, or an aryl group, or an organic group having an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxy group, a protected carboxy group, a carboxy group-generating group, an imide group, or a cyano group, and which are bonded to a silicon atom via a Si-C bond, or a combination of these groups; R 4 are groups or atoms bonded to the silicon atom, which independently represent an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom, or a combination of these groups or atoms; Y is a group or atom bonded to the silicon atom and represents an alkylene group, an NH group, or an oxygen atom; b represents an integer of 1 to 3, and c represents an integer of 0 or 1. As a tenth aspect, the polymer of the component (B) is a polymer including, as a monomer component, at least one monomer selected from the group consisting of (meth)acrylic compounds, (meth)polyfunctional acrylates, allyl compounds, isocyanate compounds, isothiocyanate compounds, epoxy compounds, diamine-containing compounds, diol-containing compounds, dicarboxylic acid-containing compounds, disulfonyl chloride-containing compounds, dithiol-containing compounds, disulfide-containing compounds, divinyl-containing compounds, diallyl-containing compounds, styrene, tetracarboxylic acid anhydrides, bismaleimides, vinyl-containing compounds, lactone ring-containing compounds, lactide-containing compounds, fluorine-containing compounds, cyclic olefin-containing compounds, ethylene, propylene, and at least one silane compound selected from the group consisting of compounds represented by the following formulas (1) and (2): The present invention relates to a hollow silica organosol according to the first aspect. [ka] (In formula (1), R 1 are groups bonded to a silicon atom, and each independently represent an alkyl group, a halogenated alkyl group, an alkenyl group, or an aryl group, or an organic group having an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxy group, a protected carboxy group, a carboxy group-generating group, an imide group, or a cyano group, and which are bonded to a silicon atom via a Si-C bond, or a combination of these groups; R 2 are groups or atoms bonded to the silicon atom, which independently represent an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom, or a combination of these groups or atoms; a represents an integer of 1 to 3; In formula (2), R 3are groups bonded to a silicon atom, and each independently represent an alkyl group, a halogenated alkyl group, an alkenyl group, or an aryl group, or an organic group having an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxy group, a protected carboxy group, a carboxy group-generating group, an imide group, or a cyano group, and which are bonded to a silicon atom via a Si-C bond, or a combination of these groups; R 4 are groups or atoms bonded to the silicon atom, which independently represent an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom, or a combination of these groups or atoms; Y is a group or atom bonded to the silicon atom and represents an alkylene group, an NH group, or an oxygen atom; b represents an integer of 1 to 3, and c represents an integer of 0 or 1. According to an eleventh aspect, the present invention relates to a resin composition including the hollow silica organosol according to the first aspect and an organic resin material different from the polymer of the component (B) or a polysiloxane resin. According to a twelfth aspect, the present invention relates to the resin composition according to the eleventh aspect, in which the organic resin material is at least one selected from the group consisting of a styrene-based resin, an epoxy-based resin, a thioepoxy resin, a novolac-based resin, a cyanate-based resin, a phenol-based resin, an acrylic-based resin, a maleimide-based resin, a polyester-based resin, a urethane-based resin, a polyurea resin, a polyimide-based resin, a polyamide-based resin, a polyamic acid resin, a polyhydroxyimide resin, a polybenzoxazole resin, a polybenzimidazole resin, a polybenzothiazole resin, a polyhydroxyamide resin, a polyhydroxyazomethine resin, a polyether-based resin, a polybenzoxazine resin, a polytetrafluoroethylene-based resin, a cycloolefin polymer-based resin, an unsaturated polyester-based resin, a vinyl triazine-based resin, a polyphenylene sulfide-based resin, a crosslinkable polyphenylene oxide-based resin, a curable polyphenylene ether-based resin, and a condensation-based resin.

[0033] According to a thirteenth aspect, the present invention relates to the hollow silica organosol according to the first aspect or the resin composition according to the twelfth aspect, which has application to a semiconductor device material, a semiconductor element material, a semiconductor resist material, a nanoimprint material, an insulating film material, a copper-clad laminate material, a printed circuit board material, a printing plate material, a printing ink material, a pigment, a paint, a sealant material, a hard coat material, a 3D printing material, an anti-reflective film material, a material for an in-vehicle part, a material for an electronic part, a machine element part, an adhesive material, a battery material, a power generation material, a chargeability-imparting material, a conductivity-imparting material, a powder fluidity-imparting material, a cosmetic material, a flexible wiring material, a liquid crystal display material, an organic electroluminescence display material, a micro LED display material, a QD-EL display material, a flexible display material, an antenna material, an optical wiring material, or a sensing material. According to a fourteenth aspect, the present invention relates to the hollow silica organosol according to the first aspect or the resin composition according to the twelfth aspect, which further contains a polymerization inhibitor. According to a fifteenth aspect, the present invention relates to a cured product comprising the hollow silica organosol according to the first aspect or the resin composition according to the twelfth aspect. As a sixteenth aspect, the present invention relates to a method for producing the hollow silica organosol according to the first aspect, comprising a step of substituting an organic solvent for a water-dispersed silica sol containing aluminum atom-containing hollow silica particles by ultrafiltration, heating under reduced pressure, or heating under normal pressure. According to a seventeenth aspect, the present invention relates to a method for producing a hollow silica organosol according to the sixteenth aspect, further comprising, before or after the step of replacing with an organic solvent, a step of adding at least one silane compound selected from the group consisting of compounds represented by the following formula (1) and formula (2) to a sol containing aluminum atom-containing hollow silica particles, and heating and stirring the mixture at 10°C to 95°C for 0.1 to 20 hours: [ka] (In formula (1), R 1are groups bonded to a silicon atom, and each independently represent an alkyl group, a halogenated alkyl group, an alkenyl group, or an aryl group, or an organic group having an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxy group, a protected carboxy group, a carboxy group-generating group, an imide group, or a cyano group, and which are bonded to a silicon atom via a Si-C bond, or a combination of these groups; R 2 are groups or atoms bonded to the silicon atom, which independently represent an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom, or a combination of these groups or atoms; a represents an integer of 1 to 3; In formula (2), R 3 are groups bonded to a silicon atom, and each independently represent an alkyl group, a halogenated alkyl group, an alkenyl group, or an aryl group, or an organic group having an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxy group, a protected carboxy group, a carboxy group-generating group, an imide group, or a cyano group, and which are bonded to a silicon atom via a Si-C bond, or a combination of these groups; R 4 are groups or atoms bonded to the silicon atom, which independently represent an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom, or a combination of these groups or atoms; Y is a group or atom bonded to the silicon atom and represents an alkylene group, an NH group, or an oxygen atom; b represents an integer of 1 to 3, and c represents an integer of 0 or 1. According to an eighteenth aspect, the present invention relates to the method for producing a hollow silica organosol according to the seventeenth aspect, in which the step of adding the silane compound and heating and stirring is carried out a plurality of times. As a nineteenth aspect, the present invention relates to a method for producing a hollow silica organosol according to the seventeenth aspect or the eighteenth aspect, further comprising a step of adding a basic compound and increasing the pH by 0.1 to 7 before or after the step of adding the silane compound and heating and stirring. As a twentieth aspect, the present invention relates to the method for producing a hollow silica organosol according to the seventeenth aspect or the eighteenth aspect, further comprising, after the step of adding the silane compound and heating and stirring, a step of substituting with the organic solvent. As a 21st aspect, the present invention relates to the method for producing a hollow silica organosol according to the 19th aspect, further comprising, after the pH increasing step, a step of replacing with the organic solvent. As a twenty-second aspect, the present invention relates to a method for producing a hollow silica organosol according to the nineteenth aspect, further comprising, after the pH increasing step, a step of adding the silane compound and heating and stirring, and a step of replacing with the organic solvent. According to a twenty-third aspect, the present invention relates to a method for producing a hollow silica organosol according to the sixteenth aspect, which includes, after the step of replacing the dispersion medium with an organic solvent, a step of replacing the dispersion medium with a reactive monomer or polymer. As a 24th aspect, the present invention relates to a method for producing a hollow silica organosol according to the 17th aspect, which comprises at least one ion exchange step selected from cation exchange and anion exchange before or after the silane compound addition / heating and stirring step. As a 25th aspect, the present invention relates to the method for producing a hollow silica organosol according to the 17th aspect, which includes a step of adding a polymerization inhibitor before or after the step of adding the silane compound and heating and stirring. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a hollow silica organosol containing aluminum atom-containing hollow silica particles in a content as high as 20% to 70% by mass. In particular, the present invention can provide a hollow silica organosol that suppresses changes in DLS average particle size before and after storage at 50°C for one week, and even before and after storage at 50°C for four weeks, and that can maintain good dispersion stability. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention is directed to a hollow silica organosol comprising (A) aluminum atom-containing hollow silica particles and (B) a dispersion medium, and is particularly directed to a hollow silica organosol characterized in that the hollow silica particles of component (A) account for 20 to 70% by mass relative to the total amount (100% by mass) of the sol.

[0011] As described above, the hollow silica organosol of the present invention is a dispersion system containing (A) aluminum atom-containing hollow silica particles (hereinafter simply referred to as "hollow silica particles," "hollow silica," or "silica particles") and (B) a dispersion medium, in which the hollow silica particles (A) are dispersed as a dispersoid in the dispersion medium (B). The hollow silica particles have a silica (SiO2)-containing outer shell with a void space inside the shell. The present invention is characterized in that the hollow silica particles (component (A)) are contained at a high concentration of 20 to 70% by mass based on the total amount (100% by mass) of the organosol. The content (proportion) of the hollow silica particles based on the total amount of the organosol can be, for example, 20 to 60% by mass, 30 to 60% by mass, 34 to 60% by mass, 20 to 50% by mass, 25 to 45% by mass, 30 to 45% by mass, or 34 to 45% by mass. In this specification, the silica particle concentration in a silica sol is a value determined by a calcination method, specifically, by calcining the target silica sol at, for example, 1000°C for 30 minutes or more, and dividing the mass of the resulting calcination residue by the mass of the target silica sol. The mass of the calcination residue is also sometimes referred to as the "silica solid content."

[0012] Thus, organosols with high silica particle concentrations, such as 20% to 70% by mass, are expected to be prone to aggregation and lack dispersion stability, but the hollow silica organosol of the present invention has a unique feature of having high dispersion stability. Dispersion stability can be evaluated, for example, by the following Thermal Stability Test 1 and Thermal Stability Test 2.

[0013] <Thermal stability test 1> In the thermal stability test 1, the hollow silica organosol was kept at 50°C for one week. The average particle size measured by dynamic light scattering before the thermal stability test 1 was (X0), and the average particle size measured by dynamic light scattering after the thermal stability test 1 was (X 1w ), the ratio of particle diameter before and after the test: (X 1w The stability of the sol is evaluated by the ratio (X0) / (X). In the hollow silica organosol of the present invention, (X 1w The value of (X0) / (X0) is preferably 0.7 to 1.3, and the ratio is preferably, for example, 0.8 to 1.2, and particularly preferably, 0.9 to 1.1.

[0014] <Thermal stability test 2> In the thermal stability test 2, the hollow silica organosol was kept at 50°C for 4 weeks. The average particle size measured by dynamic light scattering before the thermal stability test 2 was (X0), the viscosity measured at 25°C was (V0), and the average particle size measured by dynamic light scattering after the thermal stability test 2 was (X 4w ), and the viscosity measured at 25°C (V 4w ), the ratio of particle diameter before and after the test: (X 4w ) / (X0) and viscosity ratio: (V 4w ) / (V0) evaluates the stability of the sol. In the hollow silica organosol of the present invention, the particle diameter ratio: (X 4w It is at least required that the ratio (X0) / (X0) is 2.0 or less, and in a preferred embodiment, the ratio can be set to 0.8 to 1.2. Also, the viscosity ratio: (V 4w The ratio (V) / (V0) is at least required to be 1.5 or less, and in a preferred embodiment, the ratio can be set to 0.8 to 1.2, and in a more preferred embodiment, 0.9 to 1.1. A sol that exhibits good dispersion stability after such a so-called severe test at 50°C for 4 weeks can be evaluated as a sol that exhibits good dispersion stability for a long period at room temperature.

[0015] The viscosity (25°C) of the hollow silica organosol according to the present invention can be set within the range of 1.0 to 100,000.0 mPa·s, 1.0 to 10,000.0 mPa·s, 1.0 to 1,000.0 mPa·s, 1.0 to 500.0 mPa·s, 1.0 to 300.0 mPa·s, 1.0 to 200.0 mPa·s, 1.0 to 100.0 mPa·s, 1.0 to 50.0 mPa·s, 1.0 to 30.0 mPa·s, or 1.0 to 20.0 mPa·s. This viscosity can be appropriately adjusted by the dispersion medium (B) described below. For example, when the dispersion medium (B) is an organic solvent with a viscosity (25°C) of 1.0 to 2.0 mPa·s, the viscosity (25°C) of a hollow silica organosol with a silica particle concentration of 30% by mass can be set in the range of 1.0 to 10.0 mPa·s. Furthermore, for example, with regard to the viscosity of the hollow silica organosol of the present invention, the viscosity measured at 25°C before the thermal stability test 1 in which the organosol is kept at 50°C for one week is (V0), and the viscosity measured at 25°C after the test is (V 1w ), the viscosity ratio: (V 1w ) / (V0) can be, for example, 1.5 or less, and the ratio can be, for example, 0.8 to 1.2, or, for example, 1.0 to 1.1.

[0016] [(A) Aluminum atom-containing hollow silica particles] The aluminum atom-containing hollow silica particles of component (A) according to the present invention are particles having a silica (SiO2)-containing outer shell with a space inside the shell.

[0017] In the aluminum-atom-containing hollow silica particles, the amount of aluminum atoms present throughout the hollow silica particles (i.e., the entire particle including the particle surface and interior) (i.e., the aluminum atom content in the hollow silica particles) is 120 to 50,000 ppm / SiO2 (silica particles) in terms of Al2O3, relative to the mass of the hollow silica particles. For example, it can be 300 to 20,000 ppm / SiO2, or 500 to 20,000 ppm / SiO2, or 500 to 10,000 ppm / SiO2, or 500 to 5,000 ppm / SiO2, or 500 to 1,000 ppm / SiO2. By adjusting the amount of aluminum atoms present throughout the hollow silica particles to 120 to 50,000 ppm / SiO2 in terms of Al2O3 relative to the mass of the hollow silica particles, the negative charge on the surface of the silica particles increases, and even when the silica particle concentration in the dispersion medium is increased, the charge repulsion occurs to an extent that the silica particles do not come into contact with each other, allowing the dispersion state to be maintained, thereby achieving both high concentration and storage stability of the hollow silica organosol. In this specification, the amount of aluminum atoms present in the entire hollow silica particle is expressed as "ppm / SiO2" as a unit showing the amount relative to the mass (g) of the hollow silica particle. The amount of aluminum atoms present throughout the hollow silica particles can be determined by a dissolution method using a hydrofluoric acid solution (also called a hydrofluoric acid solution). Specifically, the hollow silica particles are dissolved in a hydrofluoric acid solution, and the resulting solution is measured and analyzed using an ICP emission spectrometer, whereby the amount of aluminum atoms present throughout the hollow silica particles can be expressed in terms of Al2O3. More specifically, the silica sol is first dried to remove the dispersant, yielding hollow silica particles. 250 mg of the particles are then dissolved in a hydrofluoric acid solution (e.g., a mixture of 2.5 ml of nitric acid and 2.5 ml of 38% hydrofluoric acid) to obtain an aqueous solution. The amount of aluminum atoms in the aqueous solution is measured using an ICP emission spectrometer to obtain the aluminum atom content (ppm) converted to Al2O3. This is then divided by the mass of the silica particles to determine the amount of aluminum atoms present in the entire hollow silica particle (Al2O3 (ppm) / SiO2).

[0018] In the aluminum atom-containing hollow silica particles (A) according to the present invention, the aluminum atoms may be present as an aluminosilicate. In a preferred embodiment, the hollow silica particles have an aluminosilicate formed at least on the surface of the particles, and the aluminosilicate may be formed not only on the particle surface but also inside the hollow silica particles.

[0019] The average primary particle diameter of the aluminum atom-containing hollow silica particles according to the present invention can be 20 to 100 nm, for example, 30 to 100 nm, 30 to 80 nm, 40 to 100 nm, 40 to 80 nm, or 40 to 70 nm, as determined by observation with a transmission electron microscope (TEM).

[0020] In the hollow silica organosol according to the present invention, the hollow silica particles have an average particle size (DLS average particle size: Z-average particle size, harmonic mean particle size) measured by dynamic light scattering (DLS) of 20 to 150 nm, and preferably ranges from 30 to 150 nm, 40 to 150 nm, 50 to 150 nm, 50 to 120 nm, or 50 to 100 nm. The DLS average particle size represents the average value of the secondary particle size (dispersed particle size), and it can be determined that the larger the DLS average particle size, the more the silica particles in the medium are in an aggregated state. The DLS average particle diameter values ​​are (initial) values ​​before the aforementioned Thermal Stability Test 1 and Thermal Stability Test 2 are conducted. However, since the hollow silica particles in the hollow silica organosol according to the present invention are particles with excellent dispersion stability, the DLS average particle diameter value can be assumed to be substantially within the above-mentioned range even after the above tests.

[0021] In addition, the hollow silica particles according to the present invention have a specific surface area determined by the BET method (nitrogen gas adsorption method) of, for example, 18 to 200 m 2 / g, or 50-160m 2 / g, or 60-160m 2 / g, or 70 to 160 m2 / g, or 80 to 150 m 2 / g.

[0022] The outer shell of the aluminum atom-containing hollow silica particles according to the present invention can be observed with a transmission electron microscope (TEM). In the hollow silica particles according to the present invention, the thickness of the outer shell as determined by observation with a transmission electron microscope can be, for example, in the range of 3.0 to 15.0 nm, or 3.0 to 12.0 nm, preferably 3.0 to 8.0 nm.

[0023] The aluminum atom-containing hollow silica particles according to the present invention have a number density of silanol groups on the surface of the silica particles of, for example, 0.2 to 6.0 / nm 2 , or 0.5 to 5.0 particles / nm 2 , 0.5~3.0 pieces / nm 2 , 0.5~2.0 pieces / nm 2 , 0.7~2.0 pieces / nm 2 , 1.1~2.0 pieces / nm 2 The number density of silanol groups on the surface of the silica particles can be set to 0.2 / nm 2 By setting the number density of silanol groups on the surface of the silica particles to 6.0 / nm or more, the negative charge of the silica particles becomes large, and the dispersion stability of the silica particles in the dispersion medium can be improved. 2 By setting the content below, aggregation due to dehydration condensation between silanol groups among silica particles can be suppressed, dispersion stability can be improved, and a highly concentrated silica sol can be obtained. The number density of silanol groups on the surface of silica particles can be measured, for example, by the Sears method described in "Determination of Specific Surface Area of ​​Colloidal Silica by Titration with Sodium Hydroxide" (GW Sears, Jr., Analytical Chemistry, 28(12), 1981 (1956)).

[0024] The aluminum atom-containing hollow silica particles according to the present invention preferably have a surface charge (negative charge) per gram of the hollow silica particles of 20 to 200 μeq / g, or alternatively, 20 to 150 μeq / g, 20 to 100 μeq / g, 20 to 50 μeq / g, or 20 to 40 μeq / g. By maintaining the surface charge (negative charge) per gram of the silica particles at 20 μeq / g or more, the negative charge of the silica particles increases, improving the dispersion stability of the silica particles in the dispersion medium. Furthermore, maintaining the surface charge (negative charge) per gram of the silica particles at 200 μeq / g or less reduces the leakage of alkali metals present in the aluminosilicate sites into the dispersion medium through the pores of the silica particle shells over time, suppressing an increase in pH in the system and improving the dimensional stability of the hollow silica particles and the storage stability of the silica sol, and further enabling the production of a highly concentrated silica sol. Furthermore, by setting the surface charge amount (negative charge amount) to 200 μeq / g or less, the amount of aluminum eluted from the hollow silica particles can be reduced, the amount of aluminum sulfate produced can be reduced, and aggregation of particles can be suppressed.

[0025] In addition, the high absolute value of the zeta potential of hollow silica particles in the acidic region causes electrical repulsion, which is desirable from the perspective of dispersibility, and the amount of surface charge of hollow silica particles varies, as one factor, depending on the amount of aluminum atoms (aluminosilicate) present in the hollow silica particles, as described above. For example, if the amount of aluminum atoms present in the entire silica particle (as calculated as Al2O3, relative to SiO2) is less than 120 ppm / SiO2, the stability of the hollow silica particles tends to decrease. On the other hand, when the amount of aluminum atoms (Al2O3 equivalent, relative to SiO2) present in the entire silica particles is 50,000 ppm / SiO2 or more, the particle size after doping tends to increase compared to the particle size measured by dynamic light scattering (DLS particle size) before doping with aluminum atoms at the aqueous sol stage.

[0026] The aluminum-atom-containing hollow silica particles according to the present invention may have a carbon content measured by elemental analysis in the range of, for example, 0.1% to 10.0% by mass, 0.1% to 5.0% by mass, 0.1% to 3.0% by mass, or 0.1% to 2.5% by mass. By controlling the carbon content of the aluminum-atom-containing hollow silica particles measured by elemental analysis to 0.1% to 10.0% by mass, the change in DLS average particle size before and after storage at 50°C for one week, and even before and after storage at 50°C for four weeks, is suppressed, and good dispersion stability can be expected to be maintained. Furthermore, when the hollow silica organosol of the present invention is used in thermosetting or photocurable materials, a carbon content of 0.1% to 10.0% by mass increases the proportion of inorganic components, which is expected to shorten curing and drying times and reduce thermal curing shrinkage. A sample of hollow silica particles to be subjected to elemental analysis can be prepared by first selecting a poor solvent and a good solvent for a hollow silica sol in which the hollow silica particles to be measured are dispersed, separating the hollow silica particles from organic components not bonded to the hollow silica particles using a centrifuge or the like, and then drying the resulting mixture so as to remove even adsorbed water.The carbon content (%) of the obtained silica particle measurement sample can be obtained by measuring the obtained silica particle measurement sample using an elemental analyzer. Furthermore, for example, with regard to the carbon content of the aluminum atom-containing hollow silica particles of the present invention, the ratio of the carbon content (Cp) measured before and after the thermal stability test 1 in which the particles are kept at 50°C for one week: (Cp after keeping at 50°C for one week) / (Cp before keeping at 50°C for one week) can be, for example, 1.5 or less, or, for example, 1.0 to 1.3.

[0027] The refractive index of the aluminum atom-containing hollow silica particles according to the present invention can be set within the range of, for example, 1.20 to 1.45, or 1.20 to 1.40, or 1.20 to 1.30.

[0028] [(B) Component: Dispersion medium] The hollow silica organosol according to the present invention contains at least one of an organic solvent, a reactive monomer, and a polymer as a dispersion medium for the component (B).

[0029] <Organic solvents> Examples of the organic solvent of component (B) include alcohols, ketones, ethers, esters, and amides. More specifically, examples include alcohols having 1 to 10 carbon atoms, ketones having 1 to 10 carbon atoms, ethers having 1 to 10 carbon atoms, esters having 1 to 10 carbon atoms, and amides. The number of carbon atoms mentioned above means the total number of carbon atoms contained in the compound such as the alcohol.

[0030] The alcohol having 1 to 10 carbon atoms includes an aliphatic alcohol, which may be a primary alcohol, a secondary alcohol, or a tertiary alcohol. Furthermore, it is also possible to use polyhydric alcohols such as dihydric alcohols and trihydric alcohols as these alcohols. Examples of the monohydric primary alcohol include methanol, ethanol, 1-propanol, 1-butanol, and 1-hexanol. Examples of the monohydric secondary alcohol include 2-propanol, 2-butanol, cyclohexanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monopropyl ether. The monohydric tertiary alcohol includes, for example, tert-butyl alcohol. Examples of the dihydric alcohol (glycol) include methanediol, ethylene glycol, propylene glycol, and diethylene glycol. The trihydric alcohol includes glycerin.

[0031] The ketone having 1 to 10 carbon atoms is preferably an aliphatic ketone, such as acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, cyclopentanone, or methylcyclopentanone.

[0032] The ether having 1 to 10 carbon atoms is preferably an aliphatic ether, such as dimethyl ether, ethyl methyl ether, diethyl ether, tetrahydrofuran, or 1,4-dioxane.

[0033] As the ester having 1 to 10 carbon atoms, an aliphatic ester can be preferably used, such as methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl lactate, methyl propionate, ethyl propionate, propyl propionate, methyl acrylate, ethyl acrylate, propyl acrylate, dimethyl maleate, diethyl maleate, dipropyl maleate, dimethyl adipate, diethyl adipate, dipropyl adipate, methyl 2-hydroxyisobutyrate, and propylene glycol monomethyl ether acetate.

[0034] Examples of the amide include N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and tetramethylurea.

[0035] <Reactive Monomers and Polymers> Examples of the reactive monomer of the component (B) include (meth)acrylic compounds, polyfunctional (meth)acrylates, vinyl structure-containing compounds (vinyl-containing compounds, divinyl-containing compounds, allyl compounds, diallyl-containing compounds, styrene, ethylene, propylene, and cyclic olefin-containing compounds), isocyanate compounds, isothiocyanate compounds, epoxy compounds, diamine-containing compounds, diol-containing compounds, dicarboxylic acid-containing compounds, disulfonyl chloride-containing compounds, dithiol-containing compounds, disulfide-containing compounds, ester structure-containing compounds (tetracarboxylic acid anhydrides, lactone ring-containing compounds, lactide-containing compounds, etc.), bismaleimides, fluorine-containing compounds, and at least one silane compound selected from the group consisting of compounds represented by formula (1) and formula (2) described below (component (C) described below). Furthermore, examples of the polymer of the component (B) include polymers containing, as a monomer component, at least one monomer selected from the various compounds listed above as reactive monomers. Organosols (monomer dispersion sols, polymer dispersion sols) using these reactive monomers or polymers as dispersion media have a fluid liquid form. From this perspective, reactive monomers / polymers that are liquid at 25°C or have a viscosity of 50,000 mPa·S or less at 25°C are preferably used as the dispersion media (B). As described above, reactive monomers and polymers can themselves be used as a dispersion medium for the sol, but if they are solid, gaseous, or highly viscous, they can be used as a dispersion medium for the sol by mixing them with an organic solvent, which will be described later.

[0036] Examples of the reactive monomer of component (B) include compounds having a radically polymerizable group, a cationically polymerizable group, or an anionically polymerizable group in the molecule, or polymerizable compounds having an ethylenically unsaturated bond in the molecule, polymerizable compounds having an epoxy ring, polymerizable compounds having an oxetane ring, and polymerizable compounds having a vinyl ether structure.

[0037] Examples of the reactive monomer of component (B) are shown below. Examples of (meth)acrylic compounds include monomers having a carboxylic acid such as acrylic acid or methacrylic acid, methyl acrylate, ethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, isobutyl acrylate, isononyl acrylate, 2-methoxyethyl acrylate, isobornyl acrylate, phenyl acrylate, 3-hydroxyphenyl acrylate, 4-hydroxyphenyl acrylate, 2-phenoxyethyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, isobutyl methacrylate, isononyl methacrylate, 2-methoxyethyl methacrylate, and isobornyl acrylate. Examples of the monomer include monomers having an ester structure typified by methacrylate, phenyl methacrylate, 3-hydroxyphenyl methacrylate, 4-hydroxyphenyl methacrylate, 2-phenoxyethyl methacrylate, benzyl methacrylate, 2-(dimethylamino)ethyl acrylate-benzyl chloride quaternary salt, and 9-anthrylmethyl methacrylate, and monomers having an ester structure typified by N-phenylacrylamide, N,N-dimethylacrylamide, acryloylmorpholine, N-(2-hydroxyethyl)acrylamide, N-isopropylacrylamide, N,N-diethylacrylamide, and N-[3-(dimethylamino)propyl]acrylamide methyl chloride quaternary salt. In addition, examples of polyfunctional (meth)acrylates include 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, 1,10-decanediol diacrylate, neopentyl glycol diacrylate, 2-hydroxy-3-methacrylpropyl acrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polytetramethylene glycol diacrylate, tricyclodecane dimethanol diacrylate, ethoxylated bisphenol A diacrylate, and trimethylolpropane triacrylate. Examples of the acrylate include methacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated glycerin triacrylate, tris-(2-acryloxyethyl)isocyanurate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol polyacrylate, and polypentaerythritol polyacrylate, as well as compounds in which the acrylate moiety is methacrylate.

[0038] [(C) Silane Compound] The hollow silica organosol of the present invention may further contain a silane compound as the following component (C). The silane compound of the component (C) can be at least one silane compound selected from the group consisting of compounds represented by the following formulas (1) and (2). [ka]

[0039] In the above formula (1), R 1are groups bonded to a silicon atom, and each independently represent an alkyl group, a halogenated alkyl group, an alkenyl group, or an aryl group, or an organic group having an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxy group, a protected carboxy group, a carboxy group-generating group, an imide group, or a cyano group, and which are bonded to a silicon atom via a Si-C bond, or a combination of these groups; R 2 are groups or atoms bonded to the silicon atom, which independently represent an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom, or a combination of these groups or atoms; a represents an integer of 1 to 3. In the definition of the groups of the silane compound in this specification, the term "independently from each other" means that multiple groups can each independently represent a group defined as an option. For example, in formula (1), R 1 If there are two or more (a is 2 to 3), multiple R 1 may be the same group (for example, all methyl groups), or may be a combination of different groups (for example, when a is 2, a methyl group and a phenyl group, or a methyl group and a (meth)acryloylpropyl group, etc.).

[0040] In the above formula (2), R 3 are groups bonded to a silicon atom, and each independently represent an alkyl group, a halogenated alkyl group, an alkenyl group, or an aryl group, or an organic group having an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxy group, a protected carboxy group, a carboxy group-generating group, an imide group, or a cyano group, and which are bonded to a silicon atom via a Si-C bond, or a combination of these groups; R 4 are groups or atoms bonded to the silicon atom, which independently represent an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom, or a combination of these groups or atoms; Y is a group or atom bonded to the silicon atom and represents an alkylene group, an NH group, or an oxygen atom; b represents an integer of 1 to 3, and c represents an integer of 0 or 1.

[0041] In the above formula, examples of the alkyl group include linear or branched alkyl groups having 1 to 18 carbon atoms and cyclic alkyl groups having 3 to 10 carbon atoms. Examples include, but are not limited to, methyl, ethyl, linear, branched, or cyclic propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups.

[0042] The halogenated alkyl group is an alkyl group substituted with one or more halogen atoms, and specific examples of such alkyl groups are the same as those mentioned above, i.e., linear or branched alkyl groups having 1 to 18 carbon atoms and cyclic alkyl groups having 3 to 10 carbon atoms. Examples of the halogen atom include a fluorine atom (such as a trifluoropropyl group), a chlorine atom, a bromine atom, and an iodine atom.

[0043] The alkenyl group may be, for example, an alkenyl group having 2 to 10 carbon atoms, which may be linear, branched, or cyclic, and the position of the double bond contained in the alkenyl group is not particularly limited. Examples include, but are not limited to, ethenyl (vinyl), linear, branched, or cyclic propenyl, butenyl, pentenyl, and hexenyl groups.

[0044] The aryl group may be, for example, an aryl group having 6 to 30 carbon atoms, such as a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 1-anthryl group, a 2-anthryl group, a 9-anthryl group, a 1-pyrenyl group, or a 2-pyrenyl group.

[0045] Examples of the organic group having an epoxy group include a glycidoxymethyl group, a glycidoxyethyl group, a glycidoxypropyl group, a glycidoxybutyl group, and a 2-(3,4-epoxycyclohexyl)ethyl group. The (meth)acryloyl group refers to both an acryloyl group and a methacryloyl group. Examples of organic groups having a (meth)acryloyl group include a methacryloyloxymethyl group, an acryloyloxymethyl group, a methacryloyloxyethyl group, an acryloyloxyethyl group, a 3-methacryloyloxypropyl group, and a 3-acryloyloxypropyl group. The methacryloyloxy group and the acryloyloxy group are also referred to as a methacryloxy group and an acryloxy group. Examples of the organic group having a mercapto group include an ethyl mercapto group, a 3-mercaptopropyl group, a butyl mercapto group, a hexyl mercapto group, an octyl mercapto group, and a mercaptophenyl group. Examples of the organic group having an amino group include an aminomethyl group, a 2-aminoethyl group, a 3-aminopropyl group, an N-2-(aminoethyl)-3-aminopropyl group, an N-(1,3-dimethyl-butylidene)aminopropyl group, an N-phenyl-3-aminopropyl group, an N-(vinylbenzyl)-2-aminoethyl-3-aminopropyl group, a dimethylaminoethyl group, and a dimethylaminopropyl group. Examples of the organic group having a carboxy group include a carboxymethyl group, a carboxyethyl group, a carboxypropyl group, and a carboxybutyl group. The term "protected carboxy group" refers to a carboxy group protected by a protecting group used in conventional organic synthesis reactions. The term "carboxy group generating group" refers to a group in which a carboxy group is esterified or amidated with alcohols, amines, or the like. Specific examples of silane compounds containing a protected carboxy group and an organic group having a carboxy group generating group include silane coupling agents having a carboxylic acid ester structure. In the silane coupling agent, the carboxylic acid ester moiety and the alkoxysilyl group may be linked by an alkylene group or an alkylene group containing a heteroatom (nitrogen atom, oxygen atom). The carboxylic acid ester moiety of the silane coupling agent is hydrolyzed to a carboxylic acid, and if the silane coupling agent contains a nitrogen atom (heteroatom), the carboxy group and amino group are present in the silane coupling agent upon hydrolysis, resulting in an amino acid. Therefore, the silane coupling agent can be used as an amino acid generator. For example, the product name X-88-475, manufactured by Shin-Etsu Chemical Co., Ltd., represented by formula (1-1), can be used. [ka]

[0046] The alkoxy group includes alkoxy groups having 1 to 10 carbon atoms, such as methoxy, ethoxy, propoxy, and isopropoxy, but is not limited to these.

[0047] The acyloxy group is a group derived by removing a hydrogen atom from the carboxy group (—COOH) of a carboxylic acid compound, and specific examples thereof include acyloxy groups having 2 to 10 carbon atoms.

[0048] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0049] Examples of the alkylene group include alkylene groups derived from the alkyl groups described above, and specific examples thereof include, but are not limited to, linear, branched, or cyclic alkylene groups having 1 to 10 carbon atoms, such as methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, and decamethylene.

[0050] A specific example of the silane compound represented by the formula (1) is a silane compound represented by the following formula (3). [ka]

[0051] In the above formula (3), R 5 are groups bonded to a silicon atom, and each independently represent an alkyl group having 1 to 3 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an organic group having a (meth)acryloyl group, an alkenyl group, or a carboxyl group-generating group and bonded to a silicon atom via a Si-C bond, or a combination of these groups; R 6 are groups or atoms bonded to a silicon atom, and each independently represents an alkoxy group having 1 to 3 carbon atoms, or a combination of these groups. d represents an integer of 1 to 3. Specific examples of these groups include those mentioned above, and examples of the alkyl group having 1 to 3 carbon atoms include the alkyl groups having 1 to 3 carbon atoms mentioned above as specific examples of the alkyl group.

[0052] Furthermore, specific examples of the silane compound represented by the formula (1) include the silane compound represented by the following formula (4). [ka]

[0053] In the above formula (4), R7 and R 8 are groups bonded to a silicon atom, each independently representing an alkyl group having 1 to 3 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an organic group having a (meth)acryloyl group and bonded to a silicon atom via a Si-C bond; R 9 are groups or atoms bonded to a silicon atom, and each independently represents an alkoxy group having 1 to 3 carbon atoms, or a combination of these groups. Specific examples of these groups include those mentioned above, and examples of the alkyl group having 1 to 3 carbon atoms and the aryl group having 6 to 10 carbon atoms include the alkyl group having 1 to 3 carbon atoms and the aryl group having 6 to 10 carbon atoms among the specific examples of the alkyl group and aryl group mentioned above.

[0054] Furthermore, specific examples of the silane compounds represented by the above formulas (1) and (2) include compounds that can form trimethylsilyl groups on the surfaces of silica particles. Examples of such compounds include compounds represented by the following formulas (1-2), (2-1) and (2-2). [ka] In the above formula (1-2), R 12 is an alkoxy group, such as a methoxy group or an ethoxy group. Silane compounds represented by the above formulas (1-2), (2-1) and (2-2) can be silane compounds manufactured by Shin-Etsu Chemical Co., Ltd.

[0055] The aluminum atom-containing hollow silica particles (A) according to the present invention may be particles whose surfaces are at least partially coated with the silane compound of the component (C). In the present invention, "coated with a silane compound" refers to an embodiment in which the surface of a silica particle is coated with a silane compound, and also includes an embodiment in which a silane compound is bonded to the surface of a silica particle. The "embodiment in which the surface of the silica particles is coated with a silane compound" may refer to an embodiment in which at least a portion of the surface of the silica particles is coated with a silane compound, i.e., it includes an embodiment in which the silane compound covers a portion of the surface of the silica particles and an embodiment in which the silane compound covers the entire surface of the silica particles. This embodiment does not require bonding between the silane compound and the surface of the silica particles. Furthermore, "an embodiment in which a silane compound is bonded to the surface of a silica particle" means an embodiment in which a silane compound is bonded to at least a portion of the surface of a silica particle, i.e., an embodiment in which the silane compound is bonded to a portion of the surface of a silica particle, an embodiment in which the silane compound is bonded to a portion of the surface of a silica particle and covers at least a portion of the surface, and even an embodiment in which the silane compound is bonded to the entire surface of a silica particle and covers the entire surface. That is, the silane compound of the component (C) can function as a surface modifier for the aluminum atom-containing hollow silica particles (A). The silane compound of component (C) controls the surface state of the aluminum atom-containing hollow silica particles (A) to have high affinity with various dispersing media, thereby improving the dispersion stability in the dispersing media, and is expected to contribute to improving the stability of high-concentration silica sol.

[0056] The hollow silica particles at least partially coated with a silane compound can be obtained, for example, by adding a silane compound to a hollow silica sol and then heat-treating the mixture at 10 to 95°C for approximately 0.1 to 20 hours. The amount of silane compound added relative to the hollow silica particles in the hollow silica sol can be, for example, a mass ratio of silane compound / hollow silica particles of 0.1 to 10.0. The hollow silica sol used to treat hollow silica particles with a silane compound is a sol that uses an aqueous or organic solvent as a dispersion medium, and is distinct from sols that use reactive monomers or polymers, which are listed as component (B) below, as a dispersion medium. In one embodiment, the hollow silica particles (A) according to the present invention have a surface area of ​​1 nm 2The particles may be those whose surfaces are coated with the silane compound of component (C) or those whose surfaces are bonded to the silane compound of component (C) at a ratio of 0.1 to 10 particles per 1 nm of the surface of the hollow silica particles. 2 The amount can be set so that the number of silicon atoms in the silane compound is, for example, about 0.1 to 10, or about 0.1 to 6, or about 0.1 to 3 per unit area.

[0057] The treatment (reaction) of silica particles with the silane compound proceeds through a reaction between silanol groups generated by hydrolysis of the silane compound and hydroxyl groups (silanol groups) on the surface of the silica particles. The hydrolysis requires the presence of water. When the silica sol is an aqueous solvent sol, the aqueous solvent plays this role. When the silica sol is an organic solvent sol in which the aqueous medium has been replaced with an organic solvent, the water remaining in the organic solvent can also play this role. For example, water present in the organic solvent at 0.01 to 1% by mass can be used for the hydrolysis.

[0058] The hydrolysis can be carried out with or without a catalyst. If the silica particle surface is on the acidic side (pH less than 7), hydrolysis can be carried out without a catalyst. When a catalyst is used, examples of the catalyst include metal chelate compounds, organic acids (acetic acid, oxalic acid, lactic acid, etc.), inorganic acids (hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, etc.), organic bases (heterocyclic amines, quaternary ammonium salts, sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, etc.), and inorganic bases (ammonia, sodium hydroxide, potassium hydroxide, etc.).

[0059] [Basic compounds] The hollow silica organosol according to the present invention may further contain a basic compound, which can adjust the pH of the organosol and the amount of surface charge. By adjusting the type and amount of the basic compound to be added, it is possible to adjust the surface charge amount of the (A) hollow silica particles to any desired surface charge amount. For example, by adding a basic compound, the surface charge amount of the hollow silica particles (A) in the hollow silica organosol of the present invention, i.e., the surface charge amount (negative charge amount) calculated per gram of hollow silica particles, can be adjusted to 20 to 200 μeq / g, or 20 to 150 μeq / g, 20 to 100 μeq / g, 20 to 50 μeq / g, or 20 to 40 μeq / g. Furthermore, the pH of the hollow silica organosol of the present invention can be adjusted to, for example, 7 to 10 by adding a basic compound.

[0060] The basic compound may be either an inorganic base or an organic base, and may contain, for example, an amine, or an amine and ammonia. The amine may be added and contained in an amount of 0.001 to 10% by mass, 0.01 to 10% by mass, or 0.1 to 10% by mass, based on the mass of the hollow silica particles. The amount of amine or amine and ammonia present can also be expressed as the total amount of nitrogen in the hollow silica particle organosol. For example, the above-mentioned base component can be contained so that the total amount of nitrogen is in the range of 0.001 to 10 mass%, 0.01 to 1 mass%, 0.01 to 0.3 mass%, or 0.01 to 0.2 mass%, typically 0.02 to 0.2 mass%, relative to the mass of the hollow silica particles.

[0061] Examples of the amine include aliphatic amines and aromatic amines, with aliphatic amines being preferred. At least one amine selected from the group consisting of primary, secondary, and tertiary amines having 1 to 10 carbon atoms can be used. The amine is water-soluble and is at least one amine selected from the group consisting of primary, secondary, and tertiary amines having 1 to 10 carbon atoms.

[0062] Examples of primary amines include monomethylamine, monoethylamine, monopropylamine, monoisopropylamine, monobutylamine, monoisobutylamine, monosecbutylamine, monotertbutylamine, monomethanolamine, monoethanolamine, monopropanolamine, monoisopropanolamine, monobutanolamine, monoisobutanolamine, monosecbutanolamine, and monotertbutanolamine. Examples of secondary amines include dimethylamine, diethylamine, dipropylamine, diisopropylamine, N-methylethylamine, N-ethylisobutylamine, dimethanolamine, diethanolamine, dipropanolamine, diisopropanolamine, N-methanolethylamine, N-methylethanolamine, N-ethanolisobutylamine, and N-ethylisobutanolamine. Examples of tertiary amines include trimethylamine, triethylamine, tripropylamine, triisopropylamine, diisopropylethylamine, tributylamine, triisobutylamine, tri-sec-butylamine, tri-tert-butylamine, trimethanolamine, triethanolamine, tripropanolamine, triisopropanolamine, tributanolamine, triisobutanolamine, tri-sec-butanolamine, tri-tert-butanolamine, tripentylamine, 3-(dimethylamino)ethyl acrylate, 2-(dimethylamino)ethyl acrylate, 2-(dimethylamino)ethyl methacrylate, 2-(diethylamino)ethyl acrylate, and 2-(diethylamino)ethyl methacrylate. The water solubility of the amine is preferably 80 g / L or more, or 100 g / L or more. Among these, primary amines and secondary amines are preferred, with secondary amines being more preferred due to their low volatility and high solubility, such as diisopropylamine and diethanolamine. Diisopropylethylamine, a tertiary amine, is also preferably used.

[0063] The pH of the hollow silica organosol according to the present invention can be adjusted from acidic to alkaline. The pH can be set to pH 1 to less than 7, or pH 2 to less than 7, on the acidic side, and pH 7 to 13 or less on the alkaline side. For example, the hollow silica organosol can be set to pH 1 to 8, pH 1 to less than 7, pH 2 to less than 7, pH 2 to less than 6, or pH 2 to less than 5. By adjusting the pH of the hollow silica organosol to 1 to 8, aggregation due to dehydration condensation between silanol groups between silica particles can be suppressed even when the silica particle concentration is increased, thereby improving dispersion stability. The adjustment to acidic is performed by adding an inorganic or organic acid, and the adjustment to alkaline is performed by adding an inorganic or organic base (e.g., the basic compounds described above).

[0064] Furthermore, when the dispersion medium (B) is an organic solvent, the pH of the hollow silica organosol can be the pH when the organic solvent sol is mixed with an equal mass of pure water at a ratio of 1:1. The pH is measured in the form of a sol of an organic solvent miscible with water, and when the solvent is subsequently replaced with a hydrophobic organic solvent, the pH is measured in advance at the stage of a hydrophilic organic solvent sol such as methanol, or the pH is measured after adding a hydrophilic organic solvent to the hydrophobic solvent sol. For example, when the dispersion medium is a hydrophilic organic solvent such as methanol sol or propylene glycol monomethyl ether sol, the pH can be measured using a solution prepared by mixing pure water and the sol in a mass ratio of 1:1. When the dispersion medium is a hydrophobic organic solvent such as methyl ethyl ketone sol, the pH can be measured using a solution prepared by mixing pure water, methanol, and methyl ethyl ketone sol in a mass ratio of 1:1:1.

[0065] [Method for producing hollow silica organosol] The hollow silica sol of the present invention is produced by a process comprising ultrafiltration, heating under reduced pressure, or heating under normal pressure to replace a water-dispersed silica sol containing aluminum atom-containing hollow silica particles with an organic solvent.

[0066] First, the water-dispersed silica sol containing aluminum atom-containing hollow silica particles can be produced by the following steps. (i) step: preparing an aqueous sol containing hollow silica particles; Step (ii): A step of adding an aluminum compound to the aqueous sol prepared in step (i) in a proportion of 0.0001 to 0.5 g, calculated as Al2O3, per 1 g of hollow silica particles, and maintaining the mixture at 40 to 260°C for 0.1 to 24 hours to obtain an aluminum atom-containing hollow silica aqueous sol.

[0067] The hollow silica particles constituting the aqueous sol containing hollow silica particles (also referred to as hollow silica aqueous sol) prepared in step (i) have an outer shell containing silica and have a space inside the outer shell. Note that the "hollow silica particles" prepared in step (i) are, so to speak, raw material hollow silica particles, and are distinguished from the aluminum atom-containing hollow silica particles described above, i.e., they are aluminum atom-free hollow silica particles (however, the inclusion of aluminum atoms at an impurity level is permitted). The raw material hollow silica particles are obtained by forming a silica-based shell on the surface of a core portion, called a template, in an aqueous dispersion medium, and then removing the core portion (template). The template can be made of an organic material (e.g., hydrophilic organic resin particles such as polyethylene glycol, polystyrene, or polyester) or an inorganic material (e.g., hydrophilic inorganic compound particles such as calcium carbonate or sodium aluminate). The aqueous sol containing hollow silica particles as the raw material prepared in step (i) can be any of a non-hydrothermally treated hollow silica aqueous sol, a hydrothermally treated hollow silica aqueous sol, or a mixture thereof. The non-hydrothermally treated hollow silica aqueous sol is an aqueous sol of hollow silica particles that has been treated in an aqueous medium via a heating temperature of less than 100°C, for example, from 20°C to less than 100°C, or from 40°C to less than 100°C, or from 50°C to less than 100°C. The hydrothermally treated hollow silica aqueous sol is an aqueous sol of hollow silica particles that has been treated in an aqueous medium via a heating temperature of from 100°C to 240°C, or from 110°C to 240°C. The raw material hollow silica aqueous sol (non-hydrothermally treated hollow silica aqueous sol, hydrothermally treated hollow silica aqueous sol, or a mixture thereof) can be in a form in which the raw material hollow silica particles in the aqueous sol contain aluminum atoms in the process (ii) described below, specifically in a form in which aluminosilicate sites are formed on the outer shells of the hollow silica particles. Because aluminosilicate sites can retain alkali metals, the raw material hollow silica aqueous sol can be selected so that aluminum atoms are present on the surface of the raw material hollow silica particles at a ratio of 120 to 50,000 ppm / SiO2 (based on the mass of the hollow silica particles) in terms of Al2O3, as measured by the so-called leaching method using a mineral acid.

[0068] In step (ii), an aluminum compound is added to the (raw material) hollow silica aqueous sol prepared in step (i) above, followed by heating and maintaining to obtain an aluminum atom-containing hollow silica aqueous sol. In this step, the aluminum compound acts on (i.e., impregnates) the raw material hollow silica particles from the outside, causing aluminum atoms to be present on the surfaces of the hollow silica particles, i.e., forming aluminosilicate sites at least on the surfaces of the particles.

[0069] When an aluminum compound is applied (impregnated) from the outside after the formation of the (raw material) hollow silica particles, there are two methods: one is to subject the hollow silica particles before impregnation to a hydrothermal treatment in advance, thereby increasing the density of the outer shell, and then impregnate the hollow silica particles with the aluminum compound by heat treatment; and the other is to impregnate hollow silica particles that have not been subjected to a hydrothermal treatment in advance with the aluminum compound by heat treatment. In either the former method or the latter method, it is preferable to impregnate the hollow silica particles with the aluminum compound so that the amount of aluminum atoms (in terms of Al2O3) present throughout the hollow silica particles is in the specific ratio described above, as measured by the dissolution method using the hydrofluoric acid aqueous solution described above.

[0070] The aluminum compound used in step (ii) can be added in an amount of 0.0001 to 0.5 g, 0.001 to 0.1 g, or 0.001 to 0.05 g calculated as Al2O3 relative to the mass of hollow silica particles in the hollow silica aqueous sol. The heating temperature in step (ii) is 40 to 260°C, or 50 to 260°C, or 60 to 240°C. The heating temperature can be 40 to less than 100°C, or 50 to less than 100°C, or 60 to less than 100°C in the case of non-hydrothermal treatment, and 100 to 260°C, or 150 to 240°C in the case of hydrothermal treatment. The heating time in step (ii) can be in the range of 0.1 to 48 hours, or 0.1 to 24 hours, or 0.1 to 10 hours, or 1 to 10 hours. Incidentally, whether the aluminum compound is impregnated into the hollow silica particles to form an aluminosilicate and whether the amount of aluminum atoms present is the desired amount depends on the treatment temperature in step (ii), and it is important to carry out the heat treatment within the above temperature range.

[0071] Specific examples of the aluminum compound include at least one aluminum compound selected from the group consisting of aluminates, aluminum alkoxides, and hydrolysates thereof. Examples of the aluminates include sodium aluminate, potassium aluminate, calcium aluminate, magnesium aluminate, ammonium aluminate, and amine aluminate. Examples of the aluminum alkoxides include aluminum isopropoxide and aluminum butoxide. Among these, aluminates such as sodium aluminate are preferably used.

[0072] The aluminum compound can be added to the hollow silica aqueous sol in the form of a solid or an aqueous solution, and is preferably added in the form of an aqueous solution. When the aluminum compound is added to the hollow silica aqueous sol in the form of an aqueous solution, the concentration of the aluminum compound in the aqueous solution can be in the range of 0.01 to 20% by mass, 0.1 to 10% by mass, or 0.5 to 5% by mass. The aluminum compound can be added while stirring the hollow silica aqueous sol. The addition may be completed before the heating, may be started before the heating and completed during the heating, or may be continued throughout the entire heating period.

[0073] The aqueous sol containing the aluminum atom-containing hollow silica particles may be subjected to a step of adding sulfuric acid to the aqueous sol and maintaining the sol at a predetermined temperature (a so-called leaching step) in order to dissolve into the solution the aluminum atom-containing components that have not been doped on the surface or inside of the hollow silica particles and the metal impurities contained in the particles. This step may be carried out by, for example, adding sulfuric acid in a proportion of about 1 ppm to 5000 ppm relative to the mass of the particles in the sol, and then maintaining the sol at 5 to 100°C for 0.1 to 48 hours. If necessary, the method may include a step of contacting the aqueous sol containing aluminum atom-containing hollow silica particles with a cation exchange resin before or after the addition of sulfuric acid and holding at a predetermined temperature in order to remove metal-containing components remaining in the system, metal-containing components eluted into the liquid by the addition of sulfuric acid, and impurity basic components such as counter ion components eluted by the added sulfuric acid and affecting the stability of the sol.

[0074] The water-dispersed silica sol containing the aluminum atom-containing hollow silica particles thus obtained can be subjected to a step of substituting an organic solvent by ultrafiltration, heating under reduced pressure, or heating under normal pressure. Examples of the organic solvent include the organic solvents listed above in [(B) Dispersion medium]. The pressure reduction conditions can be about 10 to 600 Torr, and the heating conditions can be about 30 to 200°C. The conversion from an aqueous sol to a hydrophobic organic solvent sol can be achieved by solvent-substituting the aqueous medium with a hydrophilic organic solvent (such as an alcohol), followed by further solvent-substituting with a hydrophobic organic solvent, and water may remain during this process. For example, the residual moisture (moisture content) in an alcohol sol of aluminum atom-containing hollow silica particles can be about 0.1 to 3.0% by mass, or about 0.1 to 1.0% by mass. Also, for example, the residual moisture in an organic solvent sol of aluminum atom-containing hollow silica particles (the dispersion medium is an organic solvent other than alcohol) can be about 5.0% by mass or less, 0.1% by mass or less, less than 0.1% by mass, 0.01 to 5.0% by mass, 0.01 to 2.0% by mass, 0.05 to 2.0% by mass, 0.10 to 2.0% by mass, or 0.01 to 0.5% by mass.

[0075] Before or after the step of replacing with the organic solvent, a step of treating the surfaces of the aluminum atom-containing hollow silica particles with at least one silane compound selected from the group consisting of compounds represented by formula (1) and formula (2) can be further carried out. As described above in [(C) Silane Compound], this step involves adding the silane compound to an aqueous sol or organic solvent sol containing aluminum atom-containing hollow silica particles, followed by heating and stirring at 10°C to 95°C for approximately 0.1 to 20 hours. The step of adding the silane compound and heating and stirring may be carried out multiple times, for example, 2 to 10 times, 2 to 8 times, 2 to 5 times, or 3 to 5 times.

[0076] Furthermore, before or after the step of adding the silane compound and heating and stirring, a step of adding a basic compound to increase the pH by 0.1 to 7 may be included. The basic compound to be added may be either an organic base or an inorganic base, and those listed above under [Basic Compound] may be used.

[0077] The method for producing hollow silica organosol of the present invention is not particularly limited, except that it essentially includes the steps of ultrafiltration and heating under reduced pressure or normal pressure to replace the organic solvent. For example, the step of adding a silane compound and heating and stirring (a step of treating the surfaces of aluminum-atom-containing hollow silica particles with a silane compound) and the step of adding a basic compound (pH-increasing step) are optional, and the organic solvent replacement step, the step of adding a silane compound and heating and stirring, and the step of increasing the pH can be performed in any order, or in combination multiple times. For example, after the step of adding the silane compound and heating and stirring, and / or after the step of increasing the pH, the step of replacing with an organic solvent by ultrafiltration / heating under reduced pressure / heating under normal pressure may be carried out.Furthermore, after the step of increasing the pH, the step of adding the silane compound and heating and stirring may be carried out, and then the step of replacing with an organic solvent by ultrafiltration / heating under reduced pressure / heating under normal pressure may be carried out.However, the combination of these steps is not limited.

[0078] The organic solvent sol of hollow silica particles using the organic solvent as a dispersion medium can be subjected to a step of substituting the dispersion medium with the reactive monomer or polymer to obtain the hollow silica organosol according to the present invention, in which the component (B) is the reactive monomer or polymer. For example, the reactive monomer or polymer may be added to and mixed with the organic solvent sol of the hollow silica particles, and the organic solvent may then be distilled off or reduced in volume, if necessary, by heating under reduced pressure, etc. Note that the organic solvent may remain after this operation. Alternatively, the reactive monomer or polymer may be dissolved in an organic solvent in advance, and the resulting solution may be added to and mixed with the organic solvent sol of the hollow silica particles. After that, the organic solvent may be distilled off or reduced in volume, if necessary, by heating under reduced pressure or the like (the organic solvent may remain after this operation). When the reactive monomer or polymer is added, a polymerization inhibitor (such as 4-methoxyphenol) may be blended into the sol. That is, the hollow silica organosol according to the present invention may be in an embodiment containing a polymerization inhibitor.

[0079] Examples of polymerization inhibitors include 4-methoxyphenol, hydroquinone, pyrogallol, naphthylamine, benzoquinone, tert-butylcatechol, cuprous chloride, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), N-nitrosophenylhydroxyamine salts (ammonium salts, cerous salts, etc.), nitrosophenylhydroxyamine aluminum salts, and diphenylnitrosamine. For example, 4-methoxyphenol can be contained in the hollow silica sol. The content of the polymerization inhibitor is preferably 0.00001 to 5% by mass relative to the hollow silica particles. One type of polymerization inhibitor may be used alone, or two or more types may be used. When two or more types are used, the total amount is preferably within the above range.

[0080] The method may further include a step of subjecting the aqueous dispersion sol or organosol containing the aluminum atom-containing hollow silica particles to at least one type of ion exchange selected from cation exchange and anion exchange, either before or after the addition of the silane compound. This step removes impurity ion components such as aluminum compound ions, sulfate ions, sodium ions, and ammonium ions eluted from the aluminum atom-containing hollow silica particles, thereby increasing the amount of silane compound bound to the surfaces of the hollow silica particles and stably dispersing them in the organosol.

[0081] The method may further include a step of adding a polymerization inhibitor to the aqueous dispersion sol or organosol containing the aluminum atom-containing hollow silica particles before or after the addition of the silane compound, which inhibits the polymerization of the silane compound having a polymerizable group such as a (meth)acryloyl group, thereby obtaining a highly concentrated hollow silica sol that is less susceptible to deterioration over time and can be stored for a long period of time.

[0082] [Resin composition] The present invention also covers a resin composition containing the hollow silica organosol and an organic resin material or polysiloxane resin different from the polymer of component (B). When the dispersion medium of the hollow silica organosol is an organic solvent, the resin composition according to the present invention can be prepared by removing the organic solvent to form aluminum atom-containing hollow silica particles, and then combining the aluminum atom-containing hollow silica particles with the organic resin material or polysiloxane resin. In the resin composition, the aluminum atom-containing hollow silica particles can account for, for example, 1% to 90% by mass of the total solid content (total 100% by mass), and the organic resin material can account for, for example, 99% to 10% by mass. The solid content in the resin composition refers to all components other than the solvent, and can be the value calculated from the residue obtained by heating the resin composition at a temperature of about 200 to 300°C to remove the solvent. When the component (B) is a reactive monomer or polymer, the type of the component (B) is different from the type of the organic resin material. When the component (B) is a reactive monomer or polymer, the content of the component (B) is included in the proportion of the organic resin material (99% by mass to 10% by mass) in the total solid content. The resin composition according to the present invention may also include the above-mentioned polymerization inhibitor.

[0083] The organic resin material may be, for example, a thermosetting or photocurable resin material (curable resin), such as, but not limited to, a styrene-based resin, an epoxy-based resin, a thioepoxy resin, a novolac-based resin, a cyanate-based resin, a phenol-based resin, an acrylic-based resin, a maleimide-based resin, a polyester-based resin, a urethane-based resin, a polyurea resin, a polyimide-based resin, a polyamide-based resin, a polyamic acid resin, a polyhydroxyimide resin, a polybenzoxazole resin, a polybenzimidazole resin, a polybenzothiazole resin, a polyhydroxyamide resin, a polyhydroxyazomethine resin, a polyether-based resin, a polybenzoxazine resin, a polytetrafluoroethylene-based resin, a cycloolefin polymer-based resin, an unsaturated polyester-based resin, a vinyltriazine-based resin, a polyphenylene sulfide-based resin, a crosslinkable polyphenylene oxide-based resin, a curable polyphenylene ether-based resin, and a condensation-based resin.

[0084] Furthermore, the resin composition of the present invention may contain various curing agents, such as amine-based curing agents, acid anhydride-based curing agents, radical generator-based curing agents (thermal radical generators, photoradical generators), acid generator-based curing agents (thermal acid generators or photoacid generators), and base generators (thermal base generators, photobase generators), as well as curing aids (organic phosphorus compounds, quaternary phosphonium salts, quaternary ammonium salts, etc.), as needed.

[0085] When the resin composition of the present invention is a thermosetting resin composition, it can be obtained in the form of a thermosetting varnish by mixing the thermosetting resin material (curable resin), the curing agent (such as a thermal acid generator), and optionally the curing aid. Mixing can be carried out in a reaction vessel using a stirring blade or a kneader.

[0086] Applies to The hollow silica organosol according to the present invention and a resin composition containing the organosol are suitable for use in semiconductor device materials, semiconductor element materials, semiconductor resist materials, nanoimprint materials, insulating film materials, copper-clad laminate materials, printed circuit board materials, printing plate materials, printing ink materials, pigments, paints, sealant materials, hard coat materials, 3D printing materials, anti-reflective film materials, automotive parts materials, electronic component materials, machine element parts, adhesive materials, battery materials, power generation materials, chargeability-imparting materials, conductivity-imparting materials, powder fluidity-imparting materials, cosmetic materials, flexible wiring materials, liquid crystal display materials, organic EL display materials, micro LED display materials, QD-EL display materials, flexible display materials, antenna materials, optical wiring materials, or sensing materials.

[0087] For example, thermosetting materials and photocurable materials using resin compositions containing the hollow silica organosol of the present invention have characteristics such as transparency and small shrinkage upon curing, and can be used for coating and bonding electronic components, optical components (anti-reflection coatings), and precision mechanical components. For example, it can be used to bond mobile phone and camera lenses, optical elements such as light-emitting diodes (LEDs) and semiconductor lasers (LDs), liquid crystal panels, biochips, camera lenses and prisms, magnetic components in hard disks for computers, CD and DVD player pickups (the part that captures the optical information reflected from the disc), speaker cones and coils, motor magnets, circuit boards, electronic components, and internal engine parts for automobiles. It can also be used as a hard coating material (coating material) for surface protection of automobile bodies, lamps, electrical appliances, building materials, plastics, etc., and can be applied to, for example, automobile and motorcycle bodies, headlight lenses and mirrors, plastic lenses for eyeglasses, mobile phones, game consoles, optical films, ID cards, etc. Examples of ink materials for printing on metals such as aluminum and plastics include credit cards, membership cards, switches for electrical appliances and office equipment, printing ink for keyboards, and inkjet printer ink for CDs, DVDs, etc. Other applications include the creation of complex three-dimensional hardened objects in combination with 3D CAD, photolithography for producing models of industrial products, coating of optical fibers, adhesion, optical waveguides, thick-film resists, etc. The composition can also be suitably used as an insulating resin for electronic materials such as anti-reflection films, semiconductor encapsulation materials, adhesives for electronic materials, printed wiring board materials, interlayer insulating film materials, and encapsulation materials for power modules, as well as an insulating resin for use in high-voltage equipment such as generator coils, transformer coils, and gas-insulated switchgears. [Example]

[0088] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0089] The raw materials used in the examples and comparative examples, namely, hollow silica aqueous sol, silane compound, base (pH adjuster), and organic solvent, are as follows.

[0090] (Raw material: hollow silica aqueous sol) Water-dispersed silica sol A: Product name HKT-A20-40D-1 (manufactured by Ningbo Dilato Co., Ltd.), a water-dispersed silica sol of hollow silica particles, with an average primary particle diameter of 40 nm measured by TEM, a shell thickness of 5 nm, and a specific surface area of ​​125 m2 measured by BET method. 2 / g, refractive index 1.3, silanol group density on the surface of hollow silica particles 1.6 / nm 2 Average particle size measured by DLS: 47 nm, the amount of aluminum atoms present in the entire hollow silica particle is less than 1 ppm / SiO2 in terms of Al2O3) Water-dispersed silica sol B: Product name HKT-A20-40D-2 (manufactured by Ningbo Dilato Co., Ltd.), a water-dispersed silica sol of hollow silica particles, with an average primary particle diameter of 44 nm by TEM, a shell thickness of 5 nm, and a specific surface area of ​​118 m by BET method. 2 / g, refractive index 1.3, silanol group density on the surface of hollow silica particles 2.2 / nm 2 Average particle size measured by DLS: 52 nm, the amount of aluminum atoms present in the entire hollow silica particle is less than 1 ppm / SiO2 in terms of Al2O3) Water-dispersed silica sol C: Product name HKT-A20-70D (manufactured by Ningbo Dilato Co., Ltd.), a water-dispersed silica sol of hollow silica particles, with an average primary particle diameter of 71 nm measured by TEM, a shell thickness of 6 nm, and a specific surface area of ​​102 m2 measured by BET method. 2 / g, refractive index 1.2, silanol group density on the surface of hollow silica particles 1.1 / nm 2 Average particle size measured by DLS: 87 nm, the amount of aluminum atoms present in the entire hollow silica particle is less than 1 ppm / SiO2 in terms of Al2O3)

[0091] (Silane compound (surface modifier, silanes manufactured by Shin-Etsu Chemical Co., Ltd.)) HMDS: Hexamethyldisiloxane MPMDMS: 3-methacryloxypropylmethyldimethoxysilane DMDMS: Dimethyldimethoxysilane TMPSA: 3-trimethoxysilylpropylsuccinic anhydride AcPS: 3-acryloxypropyltrimethoxysilane AAPS: 2-(allyloxymethyl)acrylate (trimethoxysilyl)propyl PTMS: Phenyltrimethoxysilane MTMS: Methyltrimethoxysilane MPDMS: Methylphenyldimethoxysilane MPS: 3-methacryloxypropyltrimethoxysilane DEDPS: Diethoxydiphenylsilane

[0092] (base) DiPA: Diisopropylamine DiPEA: Diisopropylethylamine

[0093] (organic solvent) MeOH: Methanol MEK: Methyl ethyl ketone CPN: Cyclopentanone CHN: Cyclohexanone AN: Acetone HX: Hexane PGME: Propylene glycol monomethyl ether EL: Ethyl lactate HBM: 2-hydroxyisobutyric acid methyl ester PGPE: Propylene glycol monopropyl ether MIBK: Methyl isobutyl ketone NMP: N-methyl-2-pyrrolidone IPA: i-propanol PGMEA: Propylene glycol monomethyl ether acetate

[0094] (reactive monomer) ACMO: Acryloylmorpholine

[0095] (additives) MEHQ: 4-Methoxyphenol

[0096] (Equipment used to manufacture hollow silica sol) Cation exchange resin: H-type Amberlite (trade name) IR-120B, harmonic mean diameter 0.6-0.8 mm, manufactured by Organo Corporation Mixed rotor: MIX-ROTAR MR-5 (product name), manufactured by AS ONE Corporation

[0097] According to the following methods, the physical properties of the above water-dispersed silica sol, the silica sols prepared in the Examples and Comparative Examples, and the silica sols and silica particles during the manufacturing process of the silica sols were evaluated.

[0098] (Measurement of silica particle concentration in silica sol) The silica particle concentration of the water-dispersed silica sol and the organic solvent-dispersed silica sol was calculated by placing the silica sol in a crucible, removing the solvent by heating on a hot plate, and then calcining at 1000°C. The resulting calcination residue was weighed and the silica particle concentration (% by mass) was calculated. As will be described later, the sol prepared in each example contains sulfuric acid, an amine for adjusting the pH, etc., but the organic components such as the amine are almost completely lost by volatilization / thermal decomposition after the calcination, and the amounts of these components, including sulfuric acid, added are very small, so the concentration calculated by the above method can be treated as the hollow silica particle concentration in the silica sol.

[0099] (pH measurement of silica sol) The pH of the water-dispersed silica sol was measured at 23°C using a pH meter (manufactured by DKK-TOA Corporation, product name: MM-43X). The pH of the organic solvent-dispersed silica sol was measured at 25°C using a pH meter (manufactured by DKK-TOA Corporation, product name: MM-43X) on a liquid obtained by mixing the organic solvent-dispersed silica sol and pure water in a mass ratio of 1:1 when the organic solvent serving as the dispersion medium was methanol (MeOH), or on a liquid obtained by mixing the organic solvent-dispersed silica sol, MeOH, and pure water in a mass ratio of 1:1:1 when the organic solvent was methyl ethyl ketone (MEK), cyclopentanone (CPN), or cyclohexanone (CHN).

[0100] (Viscosity measurement of silica sol) The viscosity of the water-dispersed silica sol, the organic solvent-dispersed silica sol, or the silica sol during the silica particle production process was measured at 25° C. using an Ostwald viscometer (manufactured by Shibata Scientific Co., Ltd.). The viscosity of the reactive monomer-dispersed silica sol was measured at 25°C using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.).

[0101] (Specific surface area measured by nitrogen gas adsorption method (S N2 ) Measurement The specific surface area (S N2) was measured by removing water-soluble cations in the water-dispersed silica sol with an H-type cation exchange resin (manufactured by Organo Corporation, trade name: Amberlite IR-120B), and then drying the silica sol at 290°C to prepare a measurement sample. This was then measured by the BET single-point method using a nitrogen gas adsorption specific surface area measuring device (trade name: Monosorb, manufactured by Quantachrome Instruments Japan LLC) with a mixed gas of 30% N2 (nitrogen) and 70% He (helium) as the carrier gas. The specific surface area (S) of silica particles in organic solvent-dispersed silica sols was measured by nitrogen gas adsorption. N2 ) was measured by the BET single-point method using a measurement sample (silica particles (powder) heated at 150°C) obtained in the below-described (Measurement of carbon content (Cp) by elemental analysis of hollow silica particles).

[0102] (Number density of silanol groups on the surface of hollow silica particles) The number density of silanol groups on the surface of hollow silica particles was measured by the Sears method, which was performed with reference to the description in "Determination of Specific Surface Area of ​​Colloidal Silica by Titration with Sodium Hydroxide" (GW Sears, Jr., Analytical Chemistry, 28(12), 1981 (1956)). The target hollow silica sol was adjusted with pure water and 0.1 mol / L hydrochloric acid to a silica particle concentration of 1% by mass and a pH of 3 to 3.5, and this was used as a measurement sample. The obtained measurement sample was titrated with a 0.1 mol / L aqueous sodium hydroxide solution, and the number density of silanol groups on the hollow silica particle surface was calculated using the following formula. ρ = (A × f × 6022) ÷ (C × S) In the above formula, ρ, A, f, C, and S are respectively ρ: silanol group density (number / nm 2 ), A: Drop volume (mL) of 0.1 mol / L sodium hydroxide aqueous solution at pH 4-9, f: Factor of 0.1 mol / L sodium hydroxide aqueous solution, C: Mass of silica particles (g), S: Specific surface area of ​​silica particles measured by nitrogen gas adsorption method (m2 / g).

[0103] (Measuring average particle size by DLS method (average particle size by dynamic light scattering)) The average particle size measured by the DLS method (average particle size measured by dynamic light scattering: Z-average particle size) was measured using a dynamic light scattering particle size analyzer (manufactured by Malvern Panalytical, product name: Zetasizer Nano). 0.1 g of the target silica sol was dispensed into a glass cell with a light path length of 10 mm, and the same solvent as the dispersion medium of the silica sol was added to obtain a silica sol with an adjusted silica particle concentration so that the count rate at an attenuator setting of 7 was 200 to 400 kcps. For example, MeOH was added in Example 1-1, and MEK was added in Example 1-2, which will be described later, to obtain a silica sol with an adjusted silica particle concentration so that the count rate at an attenuator setting of 7 was 200 to 400 kcps. The adjusted silica sol was placed in the cell so that the liquid level was approximately 1 cm above the bottom of the cell, and the dynamic light scattering particle size of the silica sol was measured using an attenuator setting of 7.

[0104] (Measurement of average primary particle size using a TEM (transmission electron microscope)) The particles in the silica sol were photographed using a transmission electron microscope (manufactured by JEOL Ltd., product name JEM-F200), and 300 randomly selected particles were binarized using an automatic image processing analyzer (manufactured by Nireco Corporation, product name LUZEX' AP). The diameter of the projected area converted into a circle was measured as the average primary particle diameter (HEYWOOD diameter).

[0105] (Measurement of the amount of aluminum present in the entire hollow silica particle / Dissolution method) A precisely weighed amount of hollow silica sol was dried, and 250 mg of the resulting particles were dissolved in 2.5 ml of nitric acid (Kanto Chemical Co., Inc., trade name: nitric acid 1.38, purity 60.0%) and 2.5 ml of 38% hydrofluoric acid (Tama Chemicals Co., Ltd., trade name: hydrofluoric acid) to obtain an aqueous solution. The amount of aluminum in the resulting aqueous solution was measured using an ICP-OES analyzer (Rigaku Corporation, trade name: CIROS120 EOP), and the amount of aluminum present in the entire hollow silica particles was calculated as the amount of Al2O3 relative to the mass of the hollow silica particles (Al2O3 (ppm) / SiO2).

[0106] (Measurement of surface charge of hollow silica particles) The silica sol was added to 10 mL of methanol to give a silica particle concentration of 0.5% by mass, which was used as a measurement sample. Using a particle charge meter (Voyt Turbo, product name PCD-06) and a 0.001 mol / L (N / 1000) DADMAC solution (Voyt Turbo) as a standard cation titrant, the titration value was measured until the streaming potential of the measurement sample reached zero. The titration value was divided by the amount of silica particles contained in the measurement sample to obtain the surface charge (μeq / g) per gram of hollow silica particles. DADMAC stands for poly(diallyldimethylammonium chloride).

[0107] (Measurement of carbon content (Cp) by elemental analysis of hollow silica particles) Four milliliters of the silica sol obtained in the example was added to a 42-ml pear-shaped settling tube (manufactured by Thermo Fisher Scientifics, trade name: Nalgene Oak Ridge). Four milliliters of MEK and 20 ml of HX were then added, and the mixture was left to stand for 5 minutes to induce cloudiness, separation, or precipitation due to aggregation. The mixture was then centrifuged (temperature: 5°C, rotation speed: 20,000 rpm, time: 30 minutes) using a centrifuge (manufactured by Tomy Seiko Co., Ltd., trade name: Suprema 21 High-Speed ​​Refrigerated Centrifuge) and the supernatant was removed. Four milliliters of AN was then added, and the precipitate was redissolved using a test tube mixer (As One Corporation, trade name: MVM-10). After centrifuging, the supernatant was removed. Four milliliters of AN was then added, and the precipitate was redissolved using a test tube mixer. After centrifuging, 20 ml of HX was added. After centrifuging, the supernatant was removed. The resulting precipitate (mixture) was vacuum dried (temperature: 60°C, pressure: -0.1 MPa), and the resulting powder was pulverized in a mortar for 10 minutes to obtain silica particles (powder). The resulting silica particles were heated at 150°C to remove adsorbed water, and a measurement sample was prepared. The carbon content (Cp: mass%) of the silica particles (measurement sample) was measured using an elemental analyzer (PerkinElmer, model name: Elemental Analyzer 2400II).

[0108] (Measurement of carbon content and unbound silane content (Ct) of hollow silica particles) The solvent of the silica sol obtained in the examples was heated at 150°C to remove the dispersant and adsorbed water, and a measurement sample was prepared. The measurement sample was measured using an elemental analyzer (manufactured by PerkinElmer, model name: Elemental Analyzer 2400II) to determine the total amount (Ct: mass%) of the carbon content of the hollow silica particles in the measurement sample (Cp) and the amount of carbon not contained in the particles (so-called unbonded) (derived from the silane compound, which is a surface modifier, also referred to as the unbonded silane content).

[0109] (Unit surface area of ​​hollow silica particles (unit: nm 2 Measurement of the amount (number) of bound silanes per The unit surface area of ​​silica particles (unit: nm2 The amount (number) of bound silanes per particle was calculated based on the following formula, using the amount (number) of silane compound added when preparing the organic solvent dispersion sol of hollow silica particles and the measurement results of Cp and Ct. Amount of bound silane (pieces / nm 2 ) = Silane addition amount (pieces) × Cp / Ct

[0110] (Measurement of refractive index of hollow silica particles) Measurement was carried out according to the following steps 1) to 3). 1) Preparation of varnish containing aqueous sol of hollow silica particles 20.00 g of 3-glycidoxypropyltrimethoxysilane (manufactured by Momentive, trade name SILQUEST A-187T) was weighed into a plastic container, 18.57 g of methanol and 4.57 g of 0.01 N hydrochloric acid solution were added, and the mixture was stirred at room temperature for 5 hours. 6.00 g of a previously prepared methanol solution of aluminum 2,4-pentanedionate (Al(acac)3) (10% by weight Al(acac)3) was added as a curing agent, and the mixture was stirred for 10 minutes to prepare a partial hydrolyzate of 3-glycidoxypropyltrimethoxysilane (GPS) (concentration: 43% by weight). The prepared partial hydrolyzate of GPS, water, methanol, and 0.25 g of a methanol solution (10 mass% L-7604) of a leveling agent (DOWSIL trade name L-7604) were weighed into a brown bottle so that the total amount was 25.00 g, the final solvent composition was water / methanol = 9 / 1 by weight, and the amount of hollow silica particles in the hollow silica aqueous sol was 50 phr, 100 phr, or 150 phr, and the mixture was stirred at room temperature for 30 minutes to prepare a varnish containing hollow silica particle aqueous sol (solid concentration: 4 mass%, hollow silica particle amount: 50 phr, 100 phr, or 150 phr). 2) Preparation of hollow silica particle-containing membrane Approximately 1 mL of the hollow silica particle aqueous sol-containing varnish (silica particle content: 50 phr, 100 phr, or 150 phr) obtained in step 1 was dropped onto a UV-O3-treated Si substrate and uniformly spread on the Si substrate using a spin coater (Mikasa Co., Ltd., product name Opticoat MS-B100) under the following conditions: ramp to 200 rpm over 2 seconds, 200 rpm x 10 seconds, then ramp to 800 rpm over 2 seconds, 800 rpm x 5 seconds, and then ramp down to 0 rpm over 5 seconds. The resulting film was then baked on a hot plate at 80°C for 5 minutes and then heat-treated in an oven at 120°C for 1 hour to prepare a hollow silica particle-containing film (hollow silica content: 50 phr, 100 phr, or 150 phr). 3) Measurement of the refractive index of hollow silica particle blended film and calculation of the refractive index of hollow silica particles The refractive index of the hollow silica particle-blended films obtained in 2) (hollow silica blending amount: 50 phr, 100 phr, or 150 phr) was measured using an ellipsometer (product name: Multi-Angle Spectroscopic Ellipsometer VASE, manufactured by J.A. Woollam Japan, Inc.). The refractive index of a film containing no hollow silica particles, prepared in the same manner using only the partial hydrolyzate of GPS, was also measured. The measured refractive index of the blended film was plotted against the blending amount of hollow silica particles, and the refractive index of the hollow silica particles was determined by extrapolating so that the blending amount of hollow silica particles was 100 mass%.

[0111] (Measurement of the amount of sulfuric acid in the water-dispersed silica sol (hereinafter referred to as the amount of sulfuric acid in the system)) The target water-dispersed silica sol was diluted 10 times with pure water, and the amount of sulfuric acid (ppm) in the system was measured by ion chromatography using an anion analyzer (trade name Dionex ICS-2100, manufactured by Thermo Scientific).

[0112] (Measurement of moisture content) The amount of water contained in the target sol was measured by Karl Fischer titration using a Karl Fischer moisture meter (manufactured by Kyoto Electronics Manufacturing Co., Ltd., trade name: MKA-610).

[0113] (Measurement of the amount of methanol (MeOH)) The amount of methanol (MeOH) contained in the target sol was measured using a gas chromatograph (manufactured by Shimadzu Corporation, product name: GC-2014s) under the conditions described below. Column: 3mm x 1m glass column Filler: Polar Pack Q Column temperature: 130-230°C (heating rate: 8°C / min) Carrier: N240mL / min Detector: FID Injection volume: 1μL Internal standard: acetonitrile.

[0114] (Example 1-1) Preparation of MeOH-dispersed silica sol (S1) of aluminum atom-containing hollow silica particles Step 1-1: Preparation of MeOH-dispersed silica sol A 1856 g of water-dispersed silica sol A (HKT-A20-40D-1 (Ningbo Dilato Co., Ltd., product name)) was placed in a 3 L plastic container and stirred at 650 rpm using a mechanical stirrer equipped with a glass stirring blade. While stirring, 32.2 g of a sodium aluminate aqueous solution diluted to a concentration of 1.0 mass% (calculated as Al2O3) was added dropwise over 1 minute, and the mixture was stirred at the same rotation speed for 30 minutes. 643.6 g of pure water was then added, and the mixture was stirred for an additional 10 minutes to obtain a mixture. Next, 2502 g of this mixture was placed in a 3 L stainless steel autoclave container and heated at 150°C for 5 hours while stirring at 80 rpm, after which it was cooled to below 50°C. To 1700 g of the obtained heat-treated water-dispersed silica sol, 1.51 g of an 8.2% aqueous sulfuric acid solution was added dropwise, and the mixture was stirred at room temperature at 800 rpm for 1 hour to obtain a sulfuric acid-added heat-treated water-dispersed silica sol. Next, the obtained sulfuric acid-added heat-treated water-dispersed silica sol was passed through a 200 mL column packed with cation exchange resin at a space velocity (SV) of 5 / hour to obtain a water-dispersed silica sol of aluminum atom-containing hollow silica particles. The resulting water-dispersed silica sol was then heated at 80°C for 10 hours, cooled to 30°C or below, and then passed through a cation exchange resin packed in a column again at a space velocity (SV) of 5 / hour to obtain a water-dispersed silica sol of aluminum atom-containing hollow silica particles. The pH of the obtained water-dispersed silica sol of aluminum atom-containing hollow silica particles was 2.7, and the amount of sulfuric acid in the system was 67 ppm. 2 / g, average primary particle diameter by TEM was 40 nm, silica particle concentration was 14.8 mass%, viscosity was 1.6 mPa·s, average particle diameter by DLS was 51 nm, the amount of aluminum atoms present in the entire hollow silica particle was 701 ppm / SiO2 in terms of Al2O3, the amount of surface charge converted to 1 g of hollow silica particle was 29 μeq / g, and the thickness of the outer shell was 5 nm.

[0115] Then, 1000 g of the obtained water-dispersed silica sol of aluminum atom-containing hollow silica particles was placed in a 2 L recovery flask. The pressure was reduced to 580 Torr using a rotary evaporator, and the solvent (dispersion medium) was replaced with methanol (MeOH) while heating to 120°C. Methanol was then added to adjust the concentration, yielding a 20% by mass MeOH-dispersed silica sol of aluminum atom-containing hollow silica particles. The physical properties of the obtained MeOH-dispersed silica sol were pH 3.1, average primary particle diameter 40 nm by TEM, average particle diameter 73 nm by DLS, viscosity 1.1 mPa·s, water content 1.3 mass%, and silica particle concentration 19.4 mass%.

[0116] Step 1-2: Preparation of highly concentrated MeOH-dispersed silica sol A 500 g of the 20 mass % MeOH-dispersed silica sol of aluminum atom-containing hollow silica particles obtained in step 1-1 was placed in a 1 L recovery flask. Then, using a rotary evaporator, the pressure was reduced to 580 Torr and the solvent methanol (MeOH) was distilled off while heating to 120°C, concentrating the silica particle concentration to approximately 30 mass %. The composition and physical properties of the obtained MeOH-dispersed hollow silica sol (S1) are shown in Table 1 (Table 1-1, Table 1-2, the same applies hereinafter).

[0117] (Example 1-2) Preparation of hollow silica particle MEK dispersed silica sol (S2) 460 g of the 20 mass % MeOH-dispersed silica sol of aluminum-atom-containing hollow silica particles obtained in step 1-1 of Example 1-1 was added to a 1-L recovery flask, and while stirring with a magnetic stirrer, 7.6 g of pure water, 69 g of MEK, and 15.2 g of HMDS were further added, and the mixture was heated to 60°C and maintained for 3 hours. The recovery flask containing the obtained silica sol was placed in a rotary evaporator, and distillation was carried out while supplying MEK at a bath temperature of 80°C under a reduced pressure of 550 to 350 Torr, replacing the dispersion medium from MeOH with MEK, thereby obtaining a MEK-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained MEK-dispersed hollow silica sol (S2) are shown in Table 1.

[0118] (Example 1-3) Preparation of hollow silica particle MEK dispersed silica sol (S3) 230 g of the 20 mass % MeOH-dispersed silica sol of aluminum atom-containing hollow silica particles obtained in step 1-1 of Example 1-1 was added to a 500 mL recovery flask, and while stirring with a magnetic stirrer, 3.8 g of pure water and 3.7 g of PTMS were added, and the mixture was heated to 60°C and maintained for 2 hours. DiEPA was then added so that the pH was 7.5 to 8.5, and the mixture was heated to 60°C and maintained for 2 hours. 1.9 g of PTMS was then added, and the mixture was heated to 60°C and maintained for 2 hours. The eggplant-shaped flask containing the obtained silica sol was set in a rotary evaporator, and distillation was carried out while supplying MEK at a bath temperature of 80°C and a reduced pressure of 550 to 350 Torr. The dispersion medium was replaced from MeOH to MEK, thereby obtaining an MEK-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained MKE-dispersed hollow silica sol (S3) are shown in Table 1.

[0119] (Example 1-4) Preparation of hollow silica particle MeOH-dispersed silica sol (S4) 230 g of the 20 mass % MeOH-dispersed silica sol of aluminum atom-containing hollow silica particles obtained in step 1-1 of Example 1-1 was added to a 500 mL recovery flask, and 2.8 g of TMPSA was added while stirring with a magnetic stirrer, and the mixture was heated to 60° C. and maintained for 3 hours. Thereafter, the solvent methanol (MeOH) was distilled off in a rotary evaporator under reduced pressure of 580 Torr and heated to 120° C., and the silica particle concentration was concentrated to approximately 30 mass %, thereby obtaining the desired silica sol. The composition and physical properties of the obtained MeOH-dispersed hollow silica sol (S4) are shown in Table 1.

[0120] (Example 1-5) Preparation of hollow silica particle MeOH-dispersed silica sol (S5) 500 g of the 20 mass % MeOH-dispersed silica sol of aluminum-atom-containing hollow silica particles obtained in step 1-1 of Example 1-1 was added to a 1 L eggplant-shaped flask, and while stirring with a magnetic stirrer, MeOH was further added to adjust the silica particle concentration to 15.5 mass %. 4.6 g of AcPS was then added, and the mixture was heated to 60 °C and maintained for 5 hours. The pressure was then reduced to 550-350 Torr using a rotary evaporator, and the solvent methanol (MeOH) was distilled off while heating to 70 °C, resulting in a silica particle concentration of approximately 30 mass %. The target silica sol was obtained. The composition and physical properties of the obtained MeOH-dispersed hollow silica sol (S5) are shown in Table 1.

[0121] (Example 1-6) Preparation of hollow silica particle MeOH-dispersed silica sol (S6) 230 g of the 20 mass % MeOH-dispersed silica sol of aluminum atom-containing hollow silica particles obtained in step 1-1 of Example 1-1 was added to a 500 mL eggplant-shaped flask, and while stirring with a magnetic stirrer, 1.3 g of MTMS was further added, and the mixture was heated to 60° C. and maintained for 3 hours. Thereafter, the pressure was reduced to 580 Torr in a rotary evaporator, and the MeOH solvent was distilled off while heating to 120° C., concentrating the silica particle concentration to approximately 30 mass %, thereby obtaining the target silica sol. The composition and physical properties of the obtained MeOH-dispersed hollow silica sol (S6) are shown in Table 1.

[0122] (Example 1-7) Preparation of hollow silica particle MeOH-dispersed silica sol (S7) 230 g of the 20 mass % MeOH-dispersed silica sol of aluminum atom-containing hollow silica particles obtained in step 1-1 of Example 1-1 was added to a 500 mL eggplant-shaped flask, and 2.8 g of AAPS was added while stirring with a magnetic stirrer, and the mixture was heated to 60° C. and maintained for 3 hours. Thereafter, the pressure was reduced to 580 Torr in a rotary evaporator, and the solvent methanol (MeOH) was distilled off while heating to 120° C., concentrating the silica particle concentration to 30 mass % to obtain the target silica sol. The composition and physical properties of the obtained MeOH-dispersed hollow silica sol (S7) are shown in Table 1.

[0123] (Example 1-8) Preparation of hollow silica particle MEK dispersed silica sol (S8) 230 g of the 20 mass% MeOH-dispersed silica sol of aluminum-atom-containing hollow silica particles obtained in step 1-1 of Example 1-1 was added to a 500 mL eggplant-shaped flask. While stirring with a magnetic stirrer, 3.6 g of pure water, 34.5 g of MEK, and 3.3 g of MPMDMS were added, and the mixture was heated to 60 ° C and maintained for 3 hours. Next, 3.8 g of HMDS was added, and the mixture was heated to 60 ° C and maintained for 3 hours. DiPA was then added to adjust the pH to 8.0-10.0, and the mixture was heated to 60 ° C and maintained for 1 hour to obtain a MeOH-dispersed silica sol of surface-modified hollow silica particles. The mixture was then placed in a rotary evaporator, and distilled under a bath temperature of 80 ° C and a reduced pressure of 550-400 Torr while feeding MEK. The dispersion medium was replaced from MeOH to MEK, yielding the desired silica sol. The composition and physical properties of the obtained MEK-dispersed hollow silica sol (S8) are shown in Table 1.

[0124] (Example 1-9) Preparation of hollow silica particle CPN-dispersed silica sol (S9) 230 g of the 20 wt% MeOH-dispersed silica sol of aluminum-atom-containing hollow silica particles obtained in step 1-1 of Example 1-1 was added to a 500 mL eggplant-shaped flask. While stirring with a magnetic stirrer, 4.5 g of purified water, 34.5 g of MEK, and 1.7 g of DMDMS were added, and the mixture was heated to 60°C and maintained for 3 hours. Next, 3.8 g of HMDS was added, and the mixture was heated to 60°C and maintained for 3 hours. DiPA was then added to adjust the pH to 8.0-10.0, and the mixture was heated to 60°C and maintained for 1 hour to obtain a MeOH-dispersed silica sol of surface-modified hollow silica particles. The resulting MeOH-dispersed silica sol had an average primary particle diameter of 40 nm measured by TEM, an average particle diameter of 73 nm measured by DLS, a pH of 8.9, a viscosity of 1.0 mPa·s, a silica particle concentration of 16.9 wt%, and a water content of 2.7 wt%. Subsequently, 89.4 g of the obtained MeOH-dispersed silica sol of surface-modified hollow silica particles was placed in a 200 mL eggplant-shaped flask and set in a rotary evaporator. Distillation was carried out while supplying CPN at a bath temperature of 80°C and a reduced pressure of 30 to 100 Torr, and the dispersion medium was replaced from MeOH to CPN, thereby obtaining the desired silica sol. The composition and physical properties of the obtained CPN-dispersed hollow silica sol (S9) are shown in Table 1.

[0125] (Example 1-10) Preparation of hollow silica particle CHN dispersed silica sol (S10) 460 g of the 20 mass % MeOH-dispersed silica sol of aluminum-atom-containing hollow silica particles obtained in step 1-1 of Example 1-1 was added to a 500 mL recovery flask, and while stirring with a magnetic stirrer, 7.6 g of pure water, 69 g of MEK, and 15.2 g of HMDS were added, and the mixture was heated to 60°C and maintained for 3 hours. The recovery flask containing the obtained silica sol was placed in a rotary evaporator, and distillation was carried out while supplying CHN at a bath temperature of 80°C and a reduced pressure of 550 to 350 Torr, replacing the dispersion medium from MeOH with CHN to obtain a CHN-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained CNH-dispersed hollow silica sol (S10) are shown in Table 1.

[0126] (Example 1-11) Preparation of hollow silica particle MEK dispersed silica sol (S11) 250 g of a 20 mass % MeOH-dispersed silica sol of aluminum atom-containing hollow silica particles obtained in step 1-1 of Example 1-1 was added to a 500 mL plastic container, and 50 mL of a cation exchange resin was further added. The mixture was stirred at 100 rpm with a mix rotor and held for 60 minutes to obtain a MeOH-dispersed silica sol of hollow silica particles. Next, 153 g of the obtained silica sol of hollow silica particles dispersed in MeOH was added to a 300 mL recovery flask, and while stirring with a magnetic stirrer, 0.03 g of MEHQ and 1.48 g of MPMDMS were added, and the mixture was heated to 60°C and maintained for 3 hours. The recovery flask containing the obtained silica sol was placed in a rotary evaporator, and distillation was carried out while supplying MEK at a bath temperature of 80°C and a reduced pressure of 550 to 350 Torr, replacing the dispersion medium from MeOH with MEK, thereby obtaining a silica sol of hollow silica particles dispersed in MEK. The composition and physical properties of the obtained MEK-dispersed hollow silica sol (S11) are shown in Table 1.

[0127] (Example 1-12) Preparation of hollow silica particle MEK dispersed silica sol (S12) 250 g of a 20 mass % MeOH-dispersed silica sol of aluminum atom-containing hollow silica particles obtained in step 1-1 of Example 1-1 was added to a 500 mL plastic container, and 50 mL of a cation exchange resin was further added. The mixture was stirred at 100 rpm with a mix rotor and held for 60 minutes to obtain a MeOH-dispersed silica sol of hollow silica particles. Next, 153 g of the obtained MeOH-dispersed silica sol of hollow silica particles was added to a 300 mL recovery flask, and while stirring with a magnetic stirrer, 0.03 g of MEHQ and 1.48 g of MPMDMS were added, and the mixture was heated to 60°C and maintained for 3 hours. Next, 2.58 g of HMDS was added, and the mixture was heated to 60°C and maintained for 3 hours. The eggplant-shaped flask containing the obtained silica sol was set in a rotary evaporator, and distillation was carried out while supplying MEK at a bath temperature of 80°C and a reduced pressure of 550 to 350 Torr. The dispersion medium was replaced from MeOH to MEK, thereby obtaining an MEK-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained MEK-dispersed hollow silica sol (S12) are shown in Table 1.

[0128] (Example 1-13) Preparation of hollow silica particle PGME-dispersed silica sol (S13) Step 1-3: Preparation of heat-treated water-dispersed silica sol B 1841 g of water-dispersed silica sol B (HKT-A20-40D-2 (Ningbo Dilato Co., Ltd., product name)) was placed in a 3 L plastic container and stirred at 650 rpm using a mechanical stirrer equipped with a glass stirring blade. While stirring, 32.2 g of a sodium aluminate aqueous solution diluted to a concentration of 1.0 mass% in terms of Al2O3 was added dropwise over 1 minute, and the mixture was stirred at the same rotation speed for 30 minutes. 659.3 g of pure water was then added, and the mixture was stirred for an additional 10 minutes to obtain a mixture. Next, 2443 g of this mixture was placed in a 3 L stainless steel autoclave container and heated at 150°C for 5 hours while stirring at 80 rpm, and then cooled to below 50°C.

[0129] Step 1-4: Preparation of acidic water-dispersed silica sol B To 2229 g of the obtained heat-treated water-dispersed silica sol, 1.98 g of an 8.2% aqueous sulfuric acid solution was added dropwise, and the mixture was stirred at room temperature at a stirring speed of 800 rpm for 1 hour to obtain a sulfuric acid-added heat-treated water-dispersed silica sol. Next, the obtained sulfuric acid-added heat-treated water-dispersed silica sol was passed through a 200 mL column packed with cation exchange resin at a space velocity (SV) of 5 / hour to obtain a water-dispersed silica sol of aluminum atom-containing hollow silica particles. The resulting water-dispersed silica sol was then heated at 80°C for 10 hours, cooled to 30°C or below, and then passed through a cation exchange resin packed in a column again at a space velocity (SV) of 5 / hour to obtain a water-dispersed silica sol of aluminum atom-containing hollow silica particles. The pH of the obtained water-dispersed silica sol of aluminum atom-containing hollow silica particles was 2.7, and the amount of sulfuric acid in the system was 62 ppm. 2 / g, average primary particle diameter by TEM was 44 nm, shell thickness by TEM was 5 nm, silica particle concentration was 13.6 mass%, viscosity was 1.9 mPa·s, average particle diameter by DLS method was 51 nm, the amount of aluminum atoms present in the entire hollow silica particle was 716 ppm / SiO2 in terms of Al2O3, and the surface charge amount converted to 1 g of hollow silica particles was 29 μeq / g.

[0130] Step 1-5: Preparation of PGME silica sol B 1000 g of the water-dispersed sol of hollow silica particles obtained in step 1-4 was placed in a 2 L eggplant-shaped flask and set in a rotary evaporator. Distillation was carried out while supplying PGME at a bath temperature of 85-90°C and a reduced pressure of 350-100 Torr, and the dispersion medium was replaced with PGME to obtain a PGME-dispersed sol of aluminum atom-containing hollow silica particles. The physical properties of the obtained PGME sol were as follows: average particle size (DLS) of 57 nm, pH of 3.8, viscosity of 3.0 mPa·s, silica particle concentration of 19.7 mass%, and water content of 0.4 mass%. The obtained sol showed good dispersibility with no sediment.

[0131] Step 1-6: Preparation of surface-coated PGME silica sol B 450 g of the obtained PGME-dispersed silica sol of aluminum atom-containing hollow silica particles was added to a 1000 mL plastic container, and 50 mL of cation exchange resin was added. The mixture was stirred at 100 rpm with a mix rotor and held for 60 minutes to obtain a PGME-dispersed silica sol of hollow silica particles. Next, 400 g of the obtained PGME-dispersed silica sol of hollow silica particles was added to a 1000 mL recovery flask, and while stirring with a magnetic stirrer, 0.08 g of MEHQ and 3.7 g of AcPS were further added, followed by heating to 70°C and maintaining the temperature for 5 hours. The eggplant-shaped flask containing the obtained silica sol was set in a rotary evaporator, and the mixture was concentrated at a bath temperature of 60°C under reduced pressure of 300 to 50 Torr until the silica particle concentration reached approximately 30% by mass, thereby obtaining the desired PGME-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained PGME-dispersed hollow silica sol (S13) are shown in Table 1.

[0132] (Example 1-14) Preparation of hollow silica particle PGME-dispersed silica sol (S14) 500 g of the aqueous dispersion sol of hollow silica particles obtained in step 1-3 of Example 1-13 was placed in a 2-L eggplant-shaped flask and placed in a rotary evaporator. Distillation was performed while supplying PGME at a bath temperature of 85-90°C and a reduced pressure of 350-100 Torr. The dispersion medium was replaced with PGME, yielding a PGME-dispersed sol of aluminum-atom-containing hollow silica particles. The physical properties of the resulting PGME sol were as follows: average particle size (DLS) of 61 nm, pH 7.8, viscosity 3.3 mPa·s, silica particle concentration 15.1% by mass, and water content 1.4% by mass. The resulting sol showed no sediment and exhibited good dispersibility. Next, 450 g of the obtained silica sol of hollow silica particles dispersed in PGME was added to a 1000 mL plastic container, and 150 mL of cation exchange resin was added. The mixture was stirred at 100 rpm with a mix rotor and held for 60 minutes to obtain a silica sol of hollow silica particles dispersed in PGME. Next, 400 g of the obtained PGME-dispersed silica sol of hollow silica particles was added to a 1-L recovery flask, and while stirring with a magnetic stirrer, 0.06 g of MEHQ and 2.76 g of AcPS were further added, followed by heating to 60°C and maintaining the temperature for 5 hours. The eggplant-shaped flask containing the obtained silica sol was set in a rotary evaporator, and the mixture was concentrated at a bath temperature of 60°C under reduced pressure of 300 to 50 Torr until the silica particle concentration reached approximately 30% by mass, thereby obtaining the desired PGME-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained PGME-dispersed hollow silica sol (S14) are shown in Table 1.

[0133] (Example 1-15) Preparation of hollow silica particle PGME-dispersed silica sol (S15) Step 1-7: Preparation of MeOH-dispersed silica sol B 1000 g of the aqueous dispersion sol of hollow silica particles obtained in step 1-4 of Example 1-13 was placed in a 2 L eggplant-shaped flask and set in a rotary evaporator. Distillation was carried out while supplying MeOH at a bath temperature of 120°C under a reduced pressure of 580 Torr, and the dispersion medium was replaced with MeOH to obtain an MeOH dispersion sol of aluminum atom-containing hollow silica particles. The physical properties of the obtained MeOH dispersion sol were as follows: average particle size (DLS) of 65 nm, pH of 3.5, viscosity of 1.0 mPa s, silica particle concentration of 19.6 mass%, and water content of 1.1 mass%. The obtained sol showed good dispersibility with no sediment.

[0134] Step 1-8: Preparation of surface-coated MeOH-dispersed silica sol B Next, 800 g of the obtained silica sol of hollow silica particles dispersed in MeOH was added to a 2 L plastic container, and 100 ml of cation exchange resin was added. The mixture was stirred at 100 rpm with a mix rotor and held for 60 minutes to obtain a silica sol of hollow silica particles dispersed in MeOH. Next, 500 g of the obtained MeOH-dispersed silica sol of hollow silica particles was added to a 1-L recovery flask, and while stirring with a magnetic stirrer, 0.10 g of MEHQ and 4.59 g of AcPS were further added, followed by heating to 60° C. and maintaining the temperature for 5 hours.

[0135] Step 1-9: Preparation of PGME-dispersed silica sol via MeOH-dispersed sol B The resulting silica sol was placed in a rotary evaporator and distilled at a bath temperature of 85-90°C under reduced pressure of 350-100 Torr while supplying PGME. The dispersion medium was replaced with PGME, yielding a PGME-dispersed sol of aluminum-atom-containing hollow silica particles. The silica particle concentration was then concentrated to approximately 30% by mass under reduced pressure of 300-50 Torr at a bath temperature of 60°C, yielding the desired PGME-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained PGME-dispersed hollow silica sol (S15) are shown in Table 1.

[0136] (Example 1-16) Preparation of hollow silica particle MeOH-dispersed silica sol (S16) A water-dispersed silica sol of aluminum atom-containing hollow silica particles (the amount of aluminum atoms present in the entire hollow silica particle was 680 ppm / SiO2) and a MeOH-dispersed silica sol of aluminum atom-containing hollow silica particles were obtained in the same manner as in step 1-1 of Example 1-1, except that water-dispersed silica sol C (HKT-A20-70D (trade name, manufactured by Ningbo Dilato Co., Ltd.)) was used instead of water-dispersed silica sol A in step 1-1 of Example 1-1. 50 g of the obtained silica sol of aluminum atom-containing hollow silica particles dispersed in MeOH was added to a 100 mL plastic container, and 50 mL of cation exchange resin was added. The mixture was stirred at 100 rpm with a mix rotor and held for 60 minutes to obtain a silica sol of hollow silica particles dispersed in MeOH. Next, 25 g of the obtained MeOH-dispersed silica sol of hollow silica particles was added to a 50 mL recovery flask, and while stirring with a magnetic stirrer, 3.8 g of MEK, 0.16 g of a 10% MeOH solution of MEHQ diluted with MeOH, and 0.25 g of MPMDMS were added, and the mixture was heated to 60°C and maintained for 3 hours. Next, 0.29 g of HMDS was added, and the mixture was heated to 60°C and maintained for 3 hours. The eggplant-shaped flask containing the obtained silica sol was set in a rotary evaporator, and the mixture was concentrated under a bath temperature of 60°C and a reduced pressure of 300 to 100 Torr until the silica particle concentration reached approximately 30% by mass, thereby obtaining the desired silica sol of hollow silica particles dispersed in MeOH. The composition and physical properties of the obtained MeOH-dispersed hollow silica sol (S16) are shown in Table 1.

[0137] (Example 1-17) Preparation of hollow silica particle MEK dispersed silica sol (S17) A water-dispersed silica sol of aluminum-atom-containing hollow silica particles (the amount of aluminum atoms present in the entire hollow silica particle was 680 ppm / SiO in terms of Al2O3) and a MeOH-dispersed silica sol of aluminum-atom-containing hollow silica particles were obtained in the same manner as in step 1-1 of Example 1-1, except that water-dispersed silica sol C (HKT-A20-70D (trade name, manufactured by Ningbo Dilato Co., Ltd.)) was used instead of water-dispersed silica sol A in step 1-1 of Example 1-1. 50 g of the obtained silica sol of aluminum atom-containing hollow silica particles dispersed in MeOH was added to a 100 mL plastic container, and 50 mL of cation exchange resin was added. The mixture was stirred at 100 rpm with a mix rotor and held for 60 minutes to obtain a silica sol of hollow silica particles dispersed in MeOH. Next, 25 g of the obtained MeOH-dispersed silica sol of hollow silica particles was added to a 50 mL eggplant flask. While stirring with a magnetic stirrer, 3.8 g of MEK, 0.16 g of a 10% MeOH solution of MEHQ diluted with MeOH, and 0.20 g of MPDMS were added, and the mixture was heated to 60°C and maintained for 3 hours. Next, 0.29 g of HMDS was added, and the mixture was heated to 60°C and maintained for 3 hours. DiPA was then added to adjust the pH to 8.0-10.0, and the mixture was heated to 60°C and maintained for 1 hour to obtain a MeOH-dispersed silica sol of surface-modified hollow silica particles. The eggplant-shaped flask containing the obtained silica sol was set in a rotary evaporator, and distillation was carried out while supplying MEK at a bath temperature of 80°C and a reduced pressure of 550 to 350 Torr. The dispersion medium was replaced from MeOH to MEK, thereby obtaining an MEK-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained MEK-dispersed hollow silica sol (S17) are shown in Table 1.

[0138] (Example 1-18) Preparation of hollow silica particle PGME-dispersed silica sol (S18) 1856 g of water-dispersed silica sol A (HKT-A20-40D-1 (Ningbo Dilato Co., Ltd., product name)) was placed in a 3 L plastic container and stirred at 650 rpm using a mechanical stirrer equipped with a glass stirring blade. While stirring, 32.2 g of a sodium aluminate aqueous solution diluted to a concentration of 1.0 mass% (calculated as Al2O3) was added dropwise over 1 minute, and the mixture was stirred at the same rotation speed for 30 minutes. 643.6 g of pure water was then added, and the mixture was stirred for an additional 10 minutes to obtain a mixture. Next, 2502 g of this mixture was placed in a 3 L stainless steel autoclave container and heated at 150°C for 5 hours while stirring at 80 rpm, after which it was cooled to below 50°C. Then, 1000 g of the resulting water-dispersed silica sol of aluminum-atom-containing hollow silica particles was placed in a 2-L recovery flask. Using a rotary evaporator, the pressure was reduced to 580 Torr, and the solvent (dispersion medium) was replaced with methanol (MeOH) while heating to 120°C. Further methanol was added to adjust the concentration, yielding a 20% by mass MeOH-dispersed silica sol of aluminum-atom-containing hollow silica particles. 50 g of the resulting MeOH-dispersed silica sol of aluminum-atom-containing hollow silica particles was then added to a 100 mL plastic container, followed by the addition of 50 mL of cation exchange resin. The mixture was stirred at 100 rpm with a mixer rotor for 60 minutes, yielding a MeOH-dispersed silica sol of hollow silica particles. Next, 50 g of the resulting 20% ​​by mass MeOH dispersion silica sol of aluminum-atom-containing hollow silica particles was added to a 100 mL eggplant-shaped flask, and while stirring with a magnetic stirrer, MeOH was added to adjust the silica particle concentration to 15.5% by mass. Then, 2.3 g of AcPS was added, and the mixture was heated to 60°C and maintained for 5 hours. The resulting MeOH-dispersed silica sol was then placed in a rotary evaporator, and distilled at a bath temperature of 85-90°C under reduced pressure of 350-100 Torr while supplying PGME. The dispersion medium was replaced with PGME, yielding a PGME-dispersed sol of aluminum-atom-containing hollow silica particles. The silica particle concentration was then concentrated to approximately 30% by mass under reduced pressure of 300-50 Torr at a bath temperature of 60°C, yielding the desired PGME-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained PGME-dispersed hollow silica sol (S18) are shown in Table 1.

[0139] (Example 1-19) Preparation of hollow silica particle PGME-dispersed silica sol (S18) 800 g of the silica sol of hollow silica particles dispersed in MeOH obtained in step 1-7 of Example 1-15 was added to a 2 L plastic container, and 100 ml of a cation exchange resin was further added. The mixture was stirred at 100 rpm with a mix rotor and held for 60 minutes to obtain a silica sol of hollow silica particles dispersed in MeOH. Next, 500 g of the obtained MeOH-dispersed silica sol of hollow silica particles was added to a 1-L recovery flask, and while stirring with a magnetic stirrer, 0.10 g of MEHQ and 4.87 g of MPS were further added, followed by heating to 60° C. and maintaining the temperature for 5 hours. The resulting silica sol was placed in a rotary evaporator and distilled at a bath temperature of 85-90°C under reduced pressure of 350-100 Torr while supplying PGME. The dispersion medium was replaced with PGME, yielding a PGME-dispersed sol of aluminum-atom-containing hollow silica particles. The silica particle concentration was then concentrated to approximately 30% by mass under reduced pressure of 300-50 Torr at a bath temperature of 60°C, yielding the desired PGME-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained PGME-dispersed hollow silica sol (S19) are shown in Table 1.

[0140] (Example 1-20) Preparation of hollow silica particle ACMO dispersed silica sol (S20) A 100 ml eggplant-shaped flask was prepared, and 60.0 g of the MeOH-dispersed silica sol obtained in step 1-8 of Example 1-15 and 23.3 g of ACMO were placed in it. The flask was then set in a rotary evaporator, and the dispersion medium, MeOH, was distilled off under a bath temperature of 40°C and a reduced pressure of 200 to 30 Torr, to obtain an ACMO-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained ACMO-dispersed hollow silica sol (S20) are shown in Table 1.

[0141] (Example 1-21) Preparation of hollow silica particle ACMO-dispersed silica sol (S21) A 100 ml eggplant-shaped flask was prepared, and 25.0 g of the MeOH-dispersed silica sol obtained in step 1-8 of Example 1-15 and 3.9 g of ACMO were placed in it. The flask was then set in a rotary evaporator, and the dispersion medium, MeOH, was distilled off under a bath temperature of 40°C and a reduced pressure of 200 to 30 Torr, to obtain an ACMO-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained ACMO-dispersed hollow silica sol (S21) are shown in Table 1.

[0142] (Example 1-22) Preparation of hollow silica particle ACMO-dispersed silica sol (S22) 85 g of the MeOH-dispersed silica sol of hollow silica particles obtained in step 1-7 of Example 1-15 was added to a 200 mL recovery flask, and while stirring with a magnetic stirrer, 26.4 g of MeOH, 0.02 g of MEHQ, and 0.80 g of MPS were further added, followed by heating to 60°C and maintaining the temperature for 5 hours. Next, a 100 ml eggplant-shaped flask was prepared, and 60.0 g of the obtained MeOH-dispersed silica sol and 16.8 g of ACMO were placed in it. The flask was then set in a rotary evaporator, and the dispersion medium, MeOH, was distilled off under a bath temperature of 40°C and a reduced pressure of 200 to 30 Torr to obtain an ACMO-dispersed silica sol of hollow silica particles. The composition and physical properties of the obtained ACMO-dispersed hollow silica sol (S22) are shown in Table 1.

[0143] (Example 1-23) Preparation of hollow silica particle PGME-dispersed silica sol (S23) A PGME-dispersed hollow silica sol was prepared in the same manner as in Example 1-14, except that 8.28 g of AcPS was added instead of 2.76 g of AcPS in Example 1-14. The composition and physical properties of the obtained PGME-dispersed hollow silica sol (S23) are shown in Table 1.

[0144] (Example 1-24) Preparation of hollow silica particle EL-dispersed silica sol (S24) 500 g of the silica sol of hollow silica particles dispersed in MeOH obtained in step 1-7 of Example 1-15 was added to a 1 L plastic container, and 50 ml of cation exchange resin was further added. The mixture was stirred at 100 rpm with a mix rotor and held for 60 minutes to obtain a silica sol of hollow silica particles dispersed in MeOH. Next, 200 g of the resulting MeOH-dispersed silica sol of hollow silica particles was added to a 500 mL recovery flask. While stirring with a magnetic stirrer, 0.04 g of MEHQ and 5.65 g of MPMDMS were added, and the mixture was heated to 60°C and maintained for 3 hours. Next, 3.29 g of HMDS was added, and the mixture was heated to 60°C and maintained for 3 hours. DiPEA was then added to adjust the pH to 8.5, and the mixture was heated to 60°C and maintained for 1 hour, yielding a MeOH-dispersed silica sol of surface-modified hollow silica particles. The mixture was then placed in a rotary evaporator, and the MeOH dispersion medium was removed at a bath temperature of 60°C and a reduced pressure of 400 to 50 Torr, yielding a dry powder of surface-modified hollow silica particles. 13 g of the obtained dry powder of surface-modified hollow silica particles and 17 g of EL were added to a 50 ml vial and held for 8 hours while stirring at 100 rpm with a mix rotor to obtain an EL-dispersed silica sol of surface-modified hollow silica particles. Table 1 shows the composition and physical properties of the obtained EL-dispersed hollow silica sol (S24).

[0145] (Example 1-25) Preparation of hollow silica particle HBM dispersed silica sol (S25) An HBM-dispersed silica sol of surface-modified hollow silica particles was obtained in the same manner as in Example 1-24, except that HBM was used instead of mixing 13 g of the dry powder of the surface-modified hollow silica particles of Example 1-24 with EL. The composition and physical properties of the obtained HBM-dispersed hollow silica sol (S25) are shown in Table 1.

[0146] (Example 1-26) Preparation of hollow silica particle PGPE-dispersed silica sol (S26) A PGPE-dispersed silica sol of surface-modified hollow silica particles was obtained in the same manner as in Example 1-24, except that PGPE was used instead of mixing 13 g of the dry powder of the surface-modified hollow silica particles of Example 1-24 with EL. The composition and physical properties of the obtained PGPE-dispersed hollow silica sol (S26) are shown in Table 1.

[0147] (Example 1-27) Preparation of hollow silica particle MIBK dispersed silica sol (S27) An MIBK-dispersed silica sol of surface-modified hollow silica particles was obtained in the same manner as in Example 1-24, except that MIBK was used instead of mixing 13 g of the dry powder of the surface-modified hollow silica particles of Example 1-24 with EL. The composition and physical properties of the obtained MIBK-dispersed hollow silica sol (S27) are shown in Table 1.

[0148] (Example 1-28) Preparation of hollow silica particle NMP dispersed silica sol (S28) An NMP-dispersed silica sol of surface-modified hollow silica particles was obtained in the same manner as in Example 1-24, except that NMP was used instead of mixing 13 g of the dry powder of the surface-modified hollow silica particles of Example 1-24 with EL. The composition and physical properties of the obtained NMP-dispersed hollow silica sol (S28) are shown in Table 1.

[0149] (Example 1-29) Preparation of hollow silica particle IPA-dispersed silica sol (S29) An IPA-dispersed silica sol of surface-modified hollow silica particles was obtained in the same manner as in Example 1-24, except that IPA was used instead of mixing 13 g of the dry powder of the surface-modified hollow silica particles of Example 1-24 with EL. The composition and physical properties of the obtained IPA-dispersed hollow silica sol (S29) are shown in Table 1.

[0150] (Example 1-30) Preparation of hollow silica particle PGMEA-dispersed silica sol (S30) A silica sol of surface-modified hollow silica particles dispersed in MeOH was obtained in the same manner as in Example 1-24, except that 0.63 g of DEDPS was added instead of MPMDMS in Example 1-24. The mixture was then placed in a rotary evaporator, and distilled at a bath temperature of 80°C and a reduced pressure of 500 to 100 Torr while supplying PGMEA, replacing the dispersion medium with PGMEA to obtain a PGMEA-dispersed sol of aluminum atom-containing hollow silica particles. Table 1 shows the composition and physical properties of the obtained PGMEA-dispersed hollow silica sol (S30).

[0151] (Example 1-31) Preparation of hollow silica particle MeOH-dispersed silica sol (S31) 500 g of the aqueous dispersion sol of hollow silica particles obtained in Step 1-3 of Example 1-13 was placed in a 2 L eggplant-shaped flask and placed in a rotary evaporator. Distillation was performed while supplying MeOH at a bath temperature of 120 °C and a reduced pressure of 580 Torr. The dispersion medium was replaced with MeOH, yielding an MeOH dispersion sol of aluminum-atom-containing hollow silica particles. The physical properties of the resulting MeOH dispersion sol were as follows: average particle size (DLS) 68 nm, pH 6.7, viscosity 1.8 mPa·s, silica particle concentration 20.8 wt%, and water content 1.1 wt%. The resulting sol showed no sediment and exhibited good dispersibility. Next, 400 g of the obtained MeOH-dispersed silica sol of hollow silica particles was added to a 1-L recovery flask, and while stirring with a magnetic stirrer, 0.08 g of MEHQ and 3.85 g of AcPS were further added, followed by heating to 60° C. and maintaining the temperature for 5 hours. The eggplant-shaped flask containing the obtained silica sol was set in a rotary evaporator, and the mixture was concentrated under a bath temperature of 60°C and a reduced pressure of 400 to 100 Torr until the silica particle concentration reached approximately 35% by mass, thereby obtaining the desired silica sol of hollow silica particles dispersed in MeOH. Table 1 shows the composition and physical properties of the obtained hollow silica sol (S31) dispersed in MeOH.

[0152] (Example 1-32) Preparation of hollow silica particle PGME-dispersed silica sol (S32) 500 g of the aqueous dispersion sol of hollow silica particles obtained in Step 1-3 of Example 1-13 was placed in a 2 L eggplant-shaped flask and placed in a rotary evaporator. Distillation was performed while supplying MeOH at a bath temperature of 120 °C and a reduced pressure of 580 Torr. The dispersion medium was replaced with MeOH, yielding an MeOH dispersion sol of aluminum-atom-containing hollow silica particles. The physical properties of the resulting MeOH dispersion sol were as follows: average particle size (DLS) 68 nm, pH 6.7, viscosity 1.8 mPa·s, silica particle concentration 20.8 wt%, and water content 1.1 wt%. The resulting sol showed no sediment and exhibited good dispersibility. Next, 400 g of the obtained MeOH-dispersed silica sol of hollow silica particles was added to a 1-L recovery flask, and while stirring with a magnetic stirrer, 0.08 g of MEHQ and 3.85 g of AcPS were further added, followed by heating to 60° C. and maintaining the temperature for 5 hours. The resulting silica sol was placed in a rotary evaporator and distilled at a bath temperature of 85-90°C under reduced pressure of 400-150 Torr while supplying PGME. The dispersion medium was replaced with PGME, yielding a PGME-dispersed sol of aluminum-atom-containing hollow silica particles. The resulting PGME-dispersed silica sol was then concentrated at a bath temperature of 60°C under reduced pressure of 100-50 Torr until the silica particle concentration reached approximately 30% by mass, yielding the desired hollow silica particle-dispersed silica sol in PGME. The composition and physical properties of the obtained PGME-dispersed hollow silica sol (S32) are shown in Table 1.

[0153] (Comparative Example 1-1) Preparation of MeOH-dispersed silica sol of aluminum atom-free hollow silica particles 1856 g of water-dispersed silica sol A (HKT-A20-40D-1 (Ningbo Dilato Co., Ltd., trade name)) was placed in a 3 L plastic container, 643.6 g of pure water was added, and the mixture was stirred for 10 minutes at a rotation speed of 650 rpm using a mechanical stirrer equipped with a glass stirring blade. 1700 g of the obtained heat-treated water-dispersed silica sol was then added dropwise with 1.51 g of 8.2% aqueous sulfuric acid solution, and the mixture was stirred at room temperature for 1 hour at a stirring speed of 800 rpm to obtain a water-dispersed silica sol to which sulfuric acid had been added. Next, the obtained sulfuric acid-added heat-treated water-dispersed silica sol was passed through a 200 mL column packed with a cation exchange resin at a space velocity (SV) of 5 / hour. The obtained water-dispersed silica sol had a cloudy appearance, and the average particle diameter measured by DLS was 80 nm, and the particles were aggregated. In other words, a water-dispersed silica sol with good dispersibility could not be obtained using hollow silica particles that did not contain aluminum atoms.

[0154] The compositions of the dispersion sols obtained in the examples and comparative examples are shown in Table 1-1, and the physical properties of the sols are shown in Table 1-2. Table 1-2 shows the hollow silica particle concentration (silica particle concentration) [mass %], average particle diameter by DLS (DLS [nm]), average primary particle diameter by TEM (TEM [nm]), thickness of the hollow silica particle outer shell (outer shell [nm]), number density of silanol groups on the surface of hollow silica particles (-SiOH number density [number / nm 2 ]), viscosity [mPa·s], surface charge [μeq / g], pH, water content [mass%], MeOH content [mass%], carbon content of hollow silica particles (Cp [mass%]), carbon content not contained in hollow silica particles (unbound) (Ct [mass%]), amount of bound silane per unit surface area of ​​hollow silica particles (bound silane [units / nm 2 ]), appearance (good: no sediment and good dispersibility (dispersed in the dispersion medium without turbidity or aggregation, same below); poor: turbidity and aggregation), and whether or not a sol can be prepared are also shown.

[0155] [Table 1-1]

[0156] [Table 1-2]

[0157] From the above results, the hollow silica sols of Examples 1-1 to 1-32 containing hollow silica particles containing aluminum atoms were organosols with good dispersibility in organic solvents and reactive monomers despite a high concentration of the hollow silica particles of 30% by mass or more, and were sols that could be adjusted to any pH by adding an acid or ion exchange. On the other hand, Comparative Example 1-1 containing hollow silica particles not containing aluminum atoms aggregated after ion exchange after adding sulfuric acid and did not form a dispersed sol, could not be adjusted to any pH, and could not be dispersed in an organic solvent.

[0158] (Stability evaluation 1 by DLS ratio (thermal stability test 1 condition)) Example 2-1: 50 g of the MeOH-dispersed silica sol (S1) obtained in Example 1-1 was sealed in a 100 ml glass bottle and kept at 50°C for one week. Thereafter, the DLS ratio was calculated from the DLS average particle diameter of the silica sol to be evaluated before and after keeping it at 50°C using the following formula (N) as an index of change over time at 50°C for one week, and the thermal stability of the silica sol was evaluated. In the following formula (N), (X0) represents the DLS average particle diameter before thermal stability test 1 (immediately after the sol was prepared), and (X 1w ) indicates the DLS average particle size after thermal stability test 1 (after being kept at 50°C for 1 week). DLS ratio:(X 1w ) / (X0)...(Formula (N)) The DLS ratio of (S1) before and after being kept at 50°C for one week was 1.0, confirming that it had high thermal stability. The thermal stability was evaluated on a four-point scale of A to D below. The results are shown in Table 2. <Stability evaluation 1 by DLS ratio (thermal stability test 1) Evaluation criteria> A: DLS ratio is 0.70 or more and 1.30 or less B: DLS ratio is greater than 1.30 and less than 1.50 C:DLS ratio is greater than 1.50 and less than 2.00 D:DLS ratio is more than 2.00 or less than 0.70, or the silica sol becomes cloudy, phase separation occurs, or sediment occurs.

[0159] Examples 2-2 to 2-20, Examples 2-22 to 2-32: The stability of the silica sols (S2) to (S20) and (S22) to (S32) obtained in Examples 1-2 to 1-20 and Examples 1-22 to 1-32 was confirmed in the same manner as in Example 2-1. The results are shown in Table 2.

[0160] [Table 2]

[0161] As can be seen from Table 2, the hollow silica sols of Examples 1-1 to 1-20 and Examples 1-22 to 1-32, which contain hollow silica particles containing aluminum atoms, exhibited high dispersibility in organic solvents and high thermal stability even after thermal stability test 1 (maintained at 50°C for 1 week), as shown in the results of Examples 2-1 to 2-20 and Examples 2-22 to 2-32.

[0162] (Stability evaluation 2 by DLS ratio (thermal stability test 2 conditions)) Example 3-3: 50 g of the MEK-dispersed silica sol (S3) obtained in Example 1-3 was sealed in a 100 ml glass bottle and kept at 50°C for 4 weeks. Thereafter, the DLS ratio was calculated from the DLS average particle diameter of the silica sol to be evaluated before and after keeping it at 50°C using the following formula (O) as an index of change over time at 50°C for 4 weeks, and the thermal stability of the silica sol was evaluated. In the following formula (O), (X0) represents the DLS average particle diameter before thermal stability test 2 (immediately after the sol was prepared), and (X 4w ) indicates the DLS average particle size after thermal stability test 2 (after being kept at 50°C for 4 weeks). DLS ratio:(X 4w ) / (X0) ···(Formula (O)) The DLS ratio of (S3) before and after 4 weeks at 50°C was 1.0, confirming that it had higher thermal stability. The thermal stability was evaluated on a four-point scale of A to D below. The results are shown in Table 3. <Stability evaluation 2 by DLS ratio (thermal stability test 2) Evaluation criteria> A: DLS ratio is 0.80 or more and 1.20 or less B: DLS ratio is greater than 1.20 and less than 1.50 C:DLS ratio is greater than 1.50 and less than 2.00 D:DLS ratio is more than 2.00 or less than 0.80, or the silica sol becomes cloudy, phase separation or sediment occurs.

[0163] Examples 3-8, 3-17, and Reference Example 3-10: The stability of the silica sols (S8), (S17), and (S10) obtained in Examples 1-8, 1-17, and 1-10 was confirmed in the same manner as in Example 3-3. The results are shown in Table 3.

[0164] [Table 3]

[0165] As can be seen from Table 3, by adding a basic compound to hollow silica sol containing hollow silica particles containing aluminum atoms, the hollow silica sol exhibited high dispersibility in organic solvents and high thermal stability even after the more severe thermal stability test 2 (maintained at 50°C for 4 weeks).

[0166] (Stability evaluation based on carbon ratio of hollow silica particles (thermal stability test 1 condition)) Example 4-2: 50 g of the MEK-dispersed silica sol (S2) obtained in Example 1-2 was sealed in a 100 ml glass bottle and kept at 50° C. for one week. Thereafter, the carbon content (C p From the results of elemental analysis, the ratio of the carbon content of the hollow silica particles (C p The ratio was calculated using the following formula: Cp ratio: (Cp after 1 week at 50°C) / (Cp before 1 week at 50°C) The Cp ratio of (S2) before and after being kept at 50°C for one week was 1.0, and it was confirmed that the change in carbon content over time was suppressed and that it had high stability.

[0167] Examples 4-3 and 4-4: In the same manner as in Example 4-2, the C values ​​of the silica sols (S3) and (S4) obtained in Examples 1-3 and 1-4 before and after being kept at 50°C for 1 week were measured. p The ratio was confirmed, and the results are shown in Table 4.

[0168] [Table 4]

[0169] (Stability evaluation 1 based on hollow silica sol viscosity ratio (thermal stability test 1 conditions)) Example 5-1: 50 g of the MeOH-dispersed silica sol (S1) obtained in Example 1-1 was sealed in a 100 ml glass bottle and kept for 1 week at 50° C. Thereafter, the hollow silica sol viscosity ratio was calculated using the following formula as an index of change over time at 50° C. for 1 week from the viscosity of the hollow silica sol of the silica sol to be evaluated before and after keeping at 50° C. Viscosity ratio: (viscosity after holding at 50°C) / (viscosity before holding at 50°C) The viscosity ratio of the MeOH-dispersed silica sol (S1) before and after being kept at 50°C for one week was 1.05, and it was confirmed that the change over time was suppressed.

[0170] Examples 5-2 to 5-4, Examples 5-6 to 5-9: The viscosity ratios of the silica sols (S2) to (S4) and (S6) to (S9) obtained in Examples 1-2 to 1-4 and 1-6 to 1-9 before and after being kept at 50° C. for 1 week were determined in the same manner as in Example 5-1. The results are shown in Table 5.

[0171] [Table 5]

[0172] (Stability evaluation 2 based on hollow silica sol viscosity ratio (thermal stability test 2 conditions)) Example 6-4: 50 g of the MeOH-dispersed silica sol (S4) obtained in Example 1-4 was sealed in a 100 ml glass bottle and kept at 50°C for 4 weeks. After that, the hollow silica sol viscosity ratio was calculated from the hollow silica sol viscosity of the silica sol to be evaluated before and after keeping it at 50°C using the following formula (P) as an index of the change over time at 50°C for 4 weeks. In the following formula (P), (V0) represents the viscosity measured at 25°C before the thermal stability test 2 (immediately after the sol was made), and (V 4w ) indicates the viscosity measured at 25°C after heat stability test 2 (after 4 weeks at 50°C). Viscosity ratio:(V 4w ) / (V0)...(Formula (P)) The viscosity ratio of the MeOH-dispersed silica sol (S4) before and after storage at 50°C for 4 weeks was 0.95, and it was confirmed that the viscosity did not increase and the silica sol had high stability.

[0173] Examples 6-9, 6-13, and Reference Example 6-1: The viscosity ratios of the silica sols (S9), (S13), and (S1) obtained in Examples 1-9, 1-13, and 1-1 before and after 4 weeks of storage at 50°C were determined in the same manner as in Example 6-4. The results are shown in Table 6.

[0174] [Table 6]

[0175] As can be seen from Table 6, in hollow silica sols containing hollow silica particles containing aluminum atoms, organosols to which a silane compound, a surface modifier, was added showed high thermal stability, with no change in viscosity ratio even after the more severe thermal stability test 2 (held at 50°C for 4 weeks), compared to organosols to which no silane compound was added.

Claims

1. A hollow silica organosol containing the following components (A), (B), and (C), wherein component (A) is present in a proportion of 20% to 70% by mass based on the total amount (100% by mass) of the organosol: (A) Component: Hollow silica particles containing aluminum atoms, The amount of aluminum atoms present throughout the hollow silica particles is Al ２ O ３ Converted to 120 to 50,000 ppm / SiO2 relative to the mass of the hollow silica particles. ２ And, Hollow silica particles with an average particle diameter of 20-150 nm due to dynamic light scattering. (B) Component: A dispersion medium comprising one or more of the following: an organic solvent, a reactive monomer, or a polymer. (C) Component: At least one silane compound selected from the group consisting of compounds represented by the following formulas (1) and (2): 【Chemistry 1】 (In formula (1), R1 represents a group bonded to a silicon atom, independently representing an alkyl group, alkyl halide, alkenyl group, or aryl group, or an organic group having an epoxy group, (meth)acryloyl group, mercapto group, amino group, ureido group, polyether group, carboxyl group, protected carboxyl group, carboxyl group generating group, imide group, or cyano group, and bonded to a silicon atom by a Si-C bond, or a combination of these groups. R2 is a group or atom bonded to a silicon atom, independently representing an alkoxy group, an acyloxy group, a hydroxyl group, or a halogen atom, or a combination of these groups or atoms. Represents combinations, a represents an integer between 1 and 3. In formula (2), R3 represents a group bonded to a silicon atom that independently represents an alkyl group, an alkyl halide, an alkenyl group, or an aryl group, or an organic group having an epoxy group, (meth)acryloyl group, mercapto group, amino group, ureido group, polyether group, carboxyl group, protected carboxyl group, carboxyl group generating group, imide group, or cyano group and bonded to a silicon atom by a Si-C bond, or a combination of these groups. R4 is a group or atom bonded to a silicon atom, independently representing an alkoxy group, an acyloxy group, a hydroxyl group, or a halogen atom, or a combination thereof. Y represents a group or atom bonded to a silicon atom, such as an alkylene group, an NH group, or an oxygen atom. b represents an integer between 1 and 3, and c represents an integer of 0 or 1.

2. In thermal stability test 1, the hollow silica organosol is kept at 50°C for one week. A hollow silica organosol according to claim 1 that satisfies the following formula (N): Equation (N): 1.3 ≥ (X) １ｗ ) / (X ０ ) ≥ 0.7 However, (X ０ ) shows the average particle size due to dynamic light scattering before thermal stability test 1, (X １ｗ ) indicates the average particle size determined by dynamic light scattering after thermal stability test 1.

3. In thermal stability test 2, the hollow silica organosol was maintained at 50°C for 4 weeks. A hollow silica organosol according to claim 1, satisfying the following formulas (O) and (P): Equation (O): 1.2 ≥ (X) ４ｗ ) / (X ０ ) ≥ 0.8 However, (X ０ ) shows the average particle size determined by dynamic light scattering before thermal stability test 2, (X ４ｗ ) indicates the average particle size determined by dynamic light scattering after thermal stability test 2. Equation (P): 1.2 ≥ (V) ４ｗ ) / (V ０ ) ≥ 0.8 However, (V ０ ) indicates the viscosity measured at 25°C before the second thermal stability test, (V ４ｗ ) indicates the viscosity measured at 25°C after thermal stability test 2.

4. The hollow silica organosol according to claim 1, wherein the (A) hollow silica particles satisfy the following (i) to (iv): (i) The outer shell thickness of the hollow silica particles is 3 to 8 nm. (ii) The number density of silanol groups on the surface of the hollow silica particles is 0.2 to 6.0 groups / nm ２ That is, (iii) The surface charge amount per gram of the hollow silica particles is 20 μeq / g to 200 μeq / g. (iv) The carbon content of the hollow silica particles, as determined by elemental analysis, is 0.1% by mass to 10.0% by mass.

5. The hollow silica particles (A) have a surface area of ​​1 nm ２ Each particle is either coated with the silane compound of component (C) at a rate of 0.1 to 10 particles, or has the silane compound of component (C) bound to its surface. The hollow silica organosol according to claim 1.

6. The hollow silica organosol according to claim 1, further comprising a basic compound.

7. The hollow silica organosol according to claim 1, wherein the organic solvent of component (B) is selected from the group consisting of alcohols, ketones, ethers, esters, and amides.

8. The reactive monomer of component (B) is The hollow silica organosol according to claim 1, wherein the organosol is a (meth)acrylic compound, a polyfunctional (meth)acrylate, an allyl compound, an isocyanate compound, an isothiocyanate compound, an epoxy compound, a diamine-containing compound, a diol-containing compound, a dicarboxylic acid-containing compound, a disulfide-containing compound, a dithiol-containing compound, a disulfide-containing compound, a divinyl-containing compound, a diallyl-containing compound, styrene, a tetracarboxylic anhydride, a bismaleimide, a vinyl-containing compound, a lactone ring-containing compound, a lactide-containing compound, a fluorine-containing compound, a cyclic olefin-containing compound, ethylene, or propylene.

9. The polymer of component (B) is A polymer containing at least one monomer as a monomer component, selected from the group consisting of (meth)acrylic compounds, polyfunctional (meth)acrylates, allyl compounds, isocyanate compounds, isothiocyanate compounds, epoxy compounds, diamine-containing compounds, diol-containing compounds, dicarboxylic acid-containing compounds, disulfonyl chloride-containing compounds, dithiol-containing compounds, disulfide-containing compounds, divinyl-containing compounds, diallyl-containing compounds, styrene, tetracarboxylic anhydride, bismaleimide, vinyl-containing compounds, lactone ring-containing compounds, lactide-containing compounds, fluorine-containing compounds, cyclic olefin-containing compounds, ethylene, propylene, or at least one silane compound selected from the group consisting of compounds represented by the following formulas (1) and (2). The hollow silica organosol according to claim 1. 【Chemistry 2】 (In formula (1), R １ This refers to a group that is bonded to a silicon atom and independently represents an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an organic group having an epoxy group, (meth)acryloyl group, mercapto group, amino group, ureido group, polyether group, carboxyl group, protected carboxyl group, carboxyl group generating group, imide group, or cyano group, and is bonded to a silicon atom by a Si-C bond, or a combination of these groups. R ２ This refers to a group or atom bonded to a silicon atom, which independently represents an alkoxy group, an acyloxy group, a hydroxyl group, or a halogen atom, or a combination thereof. a represents an integer between 1 and 3. In formula (2), R ３ This refers to a group that is bonded to a silicon atom and independently represents an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an organic group having an epoxy group, (meth)acryloyl group, mercapto group, amino group, ureido group, polyether group, carboxyl group, protected carboxyl group, carboxyl group generating group, imide group, or cyano group, and is bonded to a silicon atom by a Si-C bond, or a combination of these groups. R ４ This refers to a group or atom bonded to a silicon atom, which independently represents an alkoxy group, an acyloxy group, a hydroxyl group, or a halogen atom, or a combination thereof. Y represents a group or atom bonded to a silicon atom, such as an alkylene group, an NH group, or an oxygen atom. b represents an integer between 1 and 3, and c represents an integer of 0 or 1.

10. A resin composition comprising the hollow silica organosol described in claim 1 and an organic resin material or polysiloxane resin different from the polymer of component (B).

11. The resin composition according to claim 10, wherein the organic resin material is at least one selected from the group consisting of styrene resins, epoxy resins, thioepoxy resins, novolac resins, cyanate resins, phenolic resins, acrylic resins, maleimide resins, polyester resins, urethane resins, polyurea resins, polyimide resins, polyamide resins, polyamic acid resins, polyhydroxyimide resins, polybenzoxazole resins, polybenzimidazole resins, polybenzothiazole resins, polyhydroxyamide resins, polyhydroxyazomethine resins, polyether resins, polybenzoxazine resins, polytetrafluoroethylene resins, cycloolefin polymer resins, unsaturated polyester resins, vinyl triazine resins, polyphenylene sulfide resins, crosslinkable polyphenylene oxide resins, curable polyphenylene ether resins, and condensation resins.

12. The hollow silica organosol according to claim 1 or the resin composition according to claim 11, which has applications for semiconductor device materials, semiconductor element materials, semiconductor resist materials, nanoimprint materials, insulating film materials, copper-clad laminate materials, printed circuit board materials, printed board materials, printing ink materials, pigments, paints, encapsulant materials, hard coat materials, 3D printing materials, anti-reflective film materials, automotive parts materials, electronic parts materials, mechanical components, adhesive materials, battery materials, power generation materials, charge-impregnating materials, conductivity-impregnating materials, powder fluidity-impregnating materials, cosmetic materials, flexible wiring materials, liquid crystal display materials, organic EL display materials, micro-LED display materials, QD-EL display materials, flexible display materials, antenna materials, optical wiring materials, or sensing materials.

13. The hollow silica organosol according to claim 1 or the resin composition according to claim 11, further comprising a polymerization inhibitor.

14. A cured product comprising the hollow silica organosol described in claim 1 or the resin composition described in claim 11.

15. A method for producing a hollow silica organosol according to claim 1, comprising the step of replacing an aqueous dispersion silica sol containing aluminum atom-containing hollow silica particles with an organic solvent by ultrafiltration, heating under reduced pressure, or heating under normal pressure.

16. A method for producing a hollow silica organosol according to claim 15, further comprising the step of adding at least one silane compound selected from the group consisting of compounds represented by the following formulas (1) and (2) to a sol containing aluminum atom-containing hollow silica particles, before or after the substitution step with the organic solvent, and heating and stirring at 10°C to 95°C for 0.1 hours to 20 hours. 【Transformation 3】 (In formula (1), R １ These are groups that bond to a silicon atom and independently represent an alkyl group, an alkyl halide, an alkenyl group, an aryl group, or an epoxy group, (meth)acryloyl group, mercapto group, amino group, ureido group, polyether group, carboxyl group, or protected group. This term represents an organic group having a ruboxy group, a carboxyl group generating group, an imide group, or a cyano group, and being bonded to a silicon atom by a Si-C bond, or a combination of these groups. R ２ This refers to a group or atom bonded to a silicon atom, which independently represents an alkoxy group, an acyloxy group, a hydroxyl group, or a halogen atom, or a combination thereof. a represents an integer between 1 and 3. In formula (2), R ３ This refers to a group that is bonded to a silicon atom and independently represents an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an organic group having an epoxy group, (meth)acryloyl group, mercapto group, amino group, ureido group, polyether group, carboxyl group, protected carboxyl group, carboxyl group generating group, imide group, or cyano group, and is bonded to a silicon atom by a Si-C bond, or a combination of these groups. R ４ This refers to a group or atom bonded to a silicon atom, which independently represents an alkoxy group, an acyloxy group, a hydroxyl group, or a halogen atom, or a combination thereof. Y represents a group or atom bonded to a silicon atom, such as an alkylene group, an NH group, or an oxygen atom. b represents an integer between 1 and 3, and c represents an integer of 0 or 1.

17. A method for producing a hollow silica organosol according to claim 16, wherein the process of adding the silane compound and heating and stirring is carried out multiple times.

18. A method for producing a hollow silica organosol according to claim 16 or claim 17, further comprising the step of adding a basic compound before or after the silane compound addition and heating and stirring step to increase the pH by 0.1 to 7.

19. A method for producing a hollow silica organosol according to claim 16 or claim 17, further comprising the step of adding the silane compound and heating and stirring, followed by the step of substituting with the organic solvent.

20. A method for producing a hollow silica organosol according to claim 18, further comprising a step of substitution with the organic solvent after the pH increasing step.

21. A method for producing a hollow silica organosol according to claim 18, further comprising the steps of adding the silane compound and heating and stirring, and replacing it with the organic solvent, after the pH increasing step.

22. A method for producing a hollow silica organosol according to claim 15, comprising the step of replacing the dispersion medium with a reactive monomer or polymer after the step of replacing with an organic solvent.

23. A method for producing a hollow silica organosol according to claim 16, comprising at least one ion exchange step selected from cation exchange or anion exchange before or after the addition and heating stirring step of the silane compound.

24. A method for producing a hollow silica organosol according to claim 16, comprising the step of adding a polymerization inhibitor before or after the step of adding the silane compound and heating and stirring.

25. A hollow silica organosol containing the following components (A) and (B), wherein component (A) is present in a proportion of 20% to 70% by mass based on the total amount (100% by mass) of the organosol, (A) Component: Hollow silica particles containing aluminum atoms, The amount of aluminum atoms present throughout the hollow silica particles is 120 to 50,000 ppm / SiO₂ relative to the mass of the hollow silica particles, in terms of Al₂O₃. Hollow silica particles with an average particle diameter of 20-150 nm due to dynamic light scattering. (B) Component: A dispersion medium comprising one or more of the following: an organic solvent, a reactive monomer, or a polymer; The hollow silica organosol (A) having hollow silica particles satisfying the following conditions (i) to (iv): (i) The outer shell thickness of the hollow silica particles is 3 to 8 nm. (ii) The number density of silanol groups on the surface of the hollow silica particles is 0.2 to 6.0 groups / nm². (iii) The surface charge amount per gram of the hollow silica particles is 20 μeq / g to 200 μeq / g. (iv) The carbon content of the hollow silica particles, as determined by elemental analysis, is 0.1% by mass to 10.0% by mass.

Images