KR102815703B1 - Hollow silica sol containing 1-valent alkali metal ion and its preparation method - Google Patents

Abstract

[Project] The present invention relates to an aqueous sol and an organic solvent sol containing highly stable hollow silica particles, and further provides a method for improving the stability of the sol having reduced storage stability and a method for producing the same.
[Solution] A hollow silica sol comprising hollow silica particles having a space inside the outer shell and monovalent alkali metal ions, wherein the monovalent alkali metal ions are included in a molar number converted into _M2O (wherein M represents a monovalent alkali metal atom) in a ratio of 7.12×10 ^-6 to 285×10 ^-6 with respect to the molar number of _SiO2 of the hollow silica particles, wherein the average particle diameter determined by a dynamic light scattering method after storage at 50°C for 48 hours is within a range of 2.0 times the average particle diameter determined by the dynamic light scattering method before storage. The average particle diameter determined by the dynamic light scattering method is 20 to 150 nm. A stabilization method for reducing the increased dynamic light scattering particle size value by adding a monovalent alkali metal ion at the above ratio to SiO ₂ of hollow silica particles in a hollow silica sol having a dynamic light scattering particle size value increased compared to the dynamic light scattering particle size at the time of manufacturing.

Description

Hollow silica sol containing 1-valent alkali metal ion and its preparation method

The present invention relates to a sol dispersed in water or an organic solvent of hollow silica particles containing monovalent alkali metal ions such as sodium ions, a method for producing the same, and a film-forming composition.

Hollow silica particles having a silica shell and a space inside the outer shell have characteristics such as low refractive index, low thermal conductivity (insulation), and electrical insulation.

Hollow silica particles are composed of a core corresponding to a hollow portion and an outer shell forming the outer side of the core, and an aqueous dispersion of hollow silica particles is obtained by a method of forming a silica layer on the outer side of the core in an aqueous medium and then removing the core.

Disclosed is silica-based fine particles having cavities inside an outer shell, characterized in that the average particle diameter is in the range of 5 to 500 nm, the refractive index is in the range of 1.15 to 1.38, the molar ratio M O _X /SiO _{2 (} wherein silica is represented as SiO ₂ and an inorganic oxide other than silica is represented as M O _X ) is in the range of 0.0001 to 0.2, and the content of an alkali metal oxide is 5 ppm or less as A ₂ O (A: alkali metal element) (see Patent Document 1).

Disclosed is a silica-based fine particle having a porous substance and/or cavity in the interior of an outer layer, wherein a ratio of a specific surface area (SB) of the fine particle measured by the BET method to a specific surface area (SC) expressed by the following formula (SB/SC) is in a range of 1.1 to 5, a refractive index is in a range of 1.15 to 1.38, a content of an alkali metal oxide is 5 ppm or less as _M2O (M: alkali metal element) per silica-based fine particle, and a content of ammonia and/or ammonium ion is 1500 ppm or less as _NH3 per silica-based fine particle (see Patent Document 2).

SC(m ² /g)=6000/Dp(nm)·ρ

(Where, Dp: average particle size of silica fine particles (nm), ρ: density (g/ml).)

Japanese Patent Publication No. 2011-046606 Japanese Patent Publication No. 2013-121911

The present invention relates to an aqueous sol and an organic solvent sol comprising highly stable hollow silica particles, and further to a method for improving the stability of the sol having reduced storage stability and a method for producing the same.

The present invention, as a first aspect, comprises a hollow silica particle having a space inside an outer shell and a monovalent alkali metal ion, wherein the monovalent alkali metal ion is contained in a molar number converted into _M2O (wherein M represents a monovalent alkali metal atom) in a ratio of 7.12×10 ^-6 to 285×10 ^-6 with respect to the molar number of _SiO2 of the hollow silica particle, wherein the average particle diameter by dynamic light scattering after storing the sol at 50°C for 48 hours is within a range of 2.0 times the average particle diameter by dynamic light scattering before the storage.

Or, a hollow silica particle having a space inside the outer shell, and a sol containing a _monovalent alkali metal ion in a molar ratio of 7.12×10 ^-6 to 285×10 ^-6 , converted to M ₂ O (wherein M is a monovalent alkali metal) with respect to SiO 2 of the hollow silica particle, wherein the hollow silica sol has a particle diameter value of 2.0 times or less than that before storage after storage by dynamic light scattering method at 50°C for 48 hours.

As a second viewpoint, the hollow silica sol described in the first viewpoint, wherein the above-mentioned monovalent alkali metal ion is a sodium ion,

As a third aspect, a hollow silica sol described in the first or second aspect, having an average particle diameter of 20 to 150 nm as determined by dynamic light scattering method,

As a fourth aspect, a hollow silica sol according to any one of the first to third aspects, which additionally includes an amine, and the amine is 0.001 to 10 mass% with respect to SiO ₂ of the hollow silica particles.

As a fifth aspect, the hollow silica sol described in the fourth aspect, wherein the amine is at least one amine selected from the group consisting of primary amines, secondary amines, and tertiary amines having 1 to 10 carbon atoms.

As a sixth aspect, the hollow silica sol described in the fourth or fifth aspect, wherein the amine is a water-soluble amine having a water solubility of 80 g/L or more.

As a seventh aspect, further, the hollow silica sol according to any one of the first to sixth aspects, wherein the hollow silica particles contain aluminum atoms forming aluminosilicate sites, the aluminum atoms are bonded to the surface of the hollow silica particles, the _mass of the aluminum atoms is in a range of 100 to 20,000 ppm in terms of Al ₂ O ₃ relative to the mass of SiO 2 of the hollow silica particles, and the mass of the aluminum atoms is a value measured by a leaching method.

Or, additionally, the hollow silica sol according to any one of the first to sixth aspects, wherein the hollow silica particles contain aluminum atoms forming aluminosilicate sites, and the aluminum atoms are bonded to the surface of the hollow silica particles at a ratio (A) of 100 to 20,000 ppm/SiO ₂ as measured by a leaching method, in terms of Al ₂ O ₃ , with respect to 1 g of SiO ₂ of the hollow silica particles.

As an eighth aspect, the hollow silica sol described in the seventh aspect, wherein the leaching method measurement for leaching aluminum atoms from a compound including aluminum atoms bonded to the surface of hollow silica particles uses an aqueous solution of at least one inorganic acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid.

Alternatively, the hollow silica sol according to the seventh aspect, wherein the hollow silica sol is a hollow silica sol comprising a compound including aluminum atoms bonded to the surface of hollow silica particles, which is obtained by leaching hollow silica particles with an aqueous solution of at least one inorganic acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid, in terms of Al ₂ O ₃ , with respect to 1 g of SiO ₂ of the hollow silica particles.

As a ninth aspect, the hollow silica sol described in the _{seventh or eighth} aspect, wherein the mass of aluminum atoms present in the entire hollow silica particles is expressed as a ratio (B) of 120 to 50,000 ppm with respect to the mass of SiO ₂ of the hollow silica particles in terms of Al 2 O 3, and the mass of the aluminum atoms is a value measured by dissolving the hollow silica particles in a hydrofluoric acid aqueous solution, and the ratio (A)/this ratio (B) is 0.002 to 1.0.

Or, the hollow silica sol according to the _7th or 8th aspect, wherein the aluminum atoms present in the entire hollow silica particles, as measured by a dissolution method in a hydrofluoric acid aqueous solution, are combined in a ratio (B) of 120 to 50,000 ppm/SiO ₂ in terms of Al 2 O ₃ relative to 1 g of SiO ₂ of the hollow silica particles, and the (A)/(B) is 0.001 to 1.0.

As a tenth aspect, a hollow silica sol according to any one of the first to ninth aspects, which includes hollow silica particles having a ratio of [specific surface area (C) of silica particles by BET method (nitrogen gas adsorption method)]/[specific surface area (D) of silica particles converted from a transmission electron microscope] of 1.40 to 5.00.

As an eleventh aspect, a hollow silica sol according to any one of the first to tenth aspects, comprising hollow silica particles having a surface charge of 5 to 250 μeq/g per 1 g in terms of SiO ₂ ,

Or, a hollow silica sol according to any one of the first to tenth aspects, comprising hollow silica particles having a surface charge of 5 to 250 μeq/g converted to 1 g of SiO ₂ of the hollow silica particles.

As a 12th viewpoint, the hollow silica particles are additionally formulated with the following formulas (1) and (2):

[Chemical Formula 1]

(In equation (1),

R ¹ is a group that binds to a silicon atom, and is independently

An organic group having an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxyl group, a protected carboxyl group, a carboxyl group-generating group, an imide group, or a cyano group, and also representing a group bonded to a silicon atom by a Si-C bond, or representing a combination of these groups,

R ² is a group or atom bonded to a silicon atom, which independently represents an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom having 1 or more carbon atoms, or a combination of these groups,

a represents an integer from 1 to 3,

In equation (2),

R ³ is a group bonded to a silicon atom, which independently represents an alkyl group, a halogenated alkyl group, an alkenyl group, 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 carboxyl group, a protected carboxyl group, a carboxyl group-generating group, an imide group, or a cyano group, and also represents a group bonded to a silicon atom via a Si-C bond, or represents a combination of these groups.

R ⁴ is a group or atom bonded to a silicon atom, which independently represents an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom having 1 or more carbon atoms, or a combination of these groups,

Y is a group or atom bonded to a silicon atom, representing an alkylene group, NH group, or oxygen atom,

b represents an integer from 1 to 3, and c represents an integer of 0 or 1.)

A hollow silica sol according to any one of the first to eleventh aspects, comprising hollow silica particles coated with at least one silane compound selected from the group consisting of compounds represented by

As a 13th aspect, a hollow silica sol according to any one of the first to twelfth aspects, wherein the dispersion medium is water, an alcohol having 1 to 10 carbon atoms, a ketone, an ether, an amide, urea, or an ester.

As a 14th viewpoint, a film-forming composition comprising hollow silica particles derived from the hollow silica sol described in any one of the 1st to 13th viewpoints and an organic resin or polysiloxane,

As a 15th viewpoint, a film having a visible light transmittance of 80% or more obtained from the film-forming composition described in the 14th viewpoint,

As the 16th viewpoint, the following processes (I) to (II):

(I) Process: A process for preparing a hollow silica sol containing a dispersion medium;

(II) Process: (I) Process of adjusting the hollow silica sol by adding monovalent alkali metal ions so that the molar ratio of monovalent alkali metal ions to SiO ₂ of the hollow silica particles in the process is 7.12×10 ^-6 to 285×10 ^-6 , converted to M ₂ O (where M represents a monovalent alkali metal atom).

A method for producing a hollow silica sol as described in any one of the first to thirteenth aspects,

As a 17th aspect, a method for producing a hollow silica sol as described in the 16th aspect, wherein the monovalent alkali metal ion in the process (II) is a sodium ion.

As an 18th aspect, the method for producing a hollow silica sol as described in the 17th aspect, wherein the adjustment of the sodium ion content in the above process (II) is performed by contacting the hollow silica sol obtained in the process (I) with a cation exchange resin or adding a sodium source.

As a 19th aspect, a method for producing a hollow silica sol as described in the 17th aspect, wherein the addition of a sodium source in the above (II) process is addition of sodium hydroxide.

As a 20th aspect, a method for producing a hollow silica sol according to any one of the 16th to 19th aspects, wherein the dispersion medium of the above process (I) and process (II) is water, an alcohol having 1 to 10 carbon atoms, a ketone, an ether, an amide, urea, or an ester.

As a 21st aspect, a method for producing a hollow silica sol as described in any one of aspects 16 to 20, adding at least one process selected from the following (i) to (iv) in the process (I), the process (II), or both processes.

(i): Adding amine to hollow silica sol,

(ii): Adding sodium aluminate as an aluminum source and heating to form aluminosilicate sites in hollow silica particles;

(iii): Replacing the dispersion medium with another dispersion medium;

(iv): additionally covering the hollow silica particles with at least one silane compound selected from the group consisting of formulae (1) and (2);

As a 22nd viewpoint, a method for stabilizing a hollow silica sol comprising hollow silica particles having a space inside an outer shell,

In hollow silica sol, the average particle size value by dynamic light scattering method has increased compared to the time of manufacture.

The above monovalent alkali metal ion is added so that the mole number converted to _M2O (where M represents a monovalent alkali metal atom) is in a mole ratio of 7.12× ^10-6 to 285× ^10-6 with respect to the mole number of _SiO2 of the hollow silica particles in the hollow silica sol.

A method for stabilizing a hollow silica sol as described in the first aspect, characterized by reducing the average particle diameter by an enhanced dynamic light scattering method.

Or, a method for stabilizing a hollow silica sol including hollow silica particles having a space inside an outer shell, characterized in that a monovalent alkali metal ion is added to a hollow silica sol having a dynamic light scattering particle diameter value increased compared to a dynamic light scattering particle diameter at the time of manufacture, in a molar ratio of 7.12×10 ^-6 to 285×10 ^-6 converted to M ₂ O (wherein M is a monovalent alkali metal) with respect to SiO ₂ of the hollow silica particles in the hollow silica sol, thereby reducing the increased dynamic light scattering particle diameter value, as described in the first aspect, and

As a 23rd aspect, there is provided a method for stabilizing a hollow silica sol as described in the 22nd aspect, wherein the above-mentioned monovalent alkali metal ion is a sodium ion.

A dispersion (hollow silica sol) containing hollow silica particles is stable, so that a hollow silica sol is obtained in which there is no aggregation of hollow silica particles and little change in the diameter of the hollow silica particles. When the hollow silica sol with high stability is used as a coating film, the change in particle diameter is small, so that a reduction in unevenness on the surface of the coating film and an improvement in transparency are achieved.

It is preferable that the alkali metal ion (e.g., sodium ion) in the hollow silica sol be within a certain range, and if it is too much, there may be problems with the dissolution of the alkali metal ion from the coating film or the electrical insulation of the coating film. In addition, if it is too little, since the hollow silica particles have a hollow interior of the outer shell and the specific gravity of the hollow silica particles themselves is lower than that of solid silica particles, if the particle repulsion is low, the particles tend to gather easily and agglomerate easily, and in that case, a certain amount of alkali metal ion (e.g., sodium ion) is required to increase the particle repulsion.

In the present invention, stability is improved by combining amine molecules and sodium ions as alkaline components. This is thought to be because the repulsive force between silica particles is improved by the mutual presence of amine molecules and sodium ions having a large volume on the particle surface.

In addition, in the present invention, it is possible to form an aluminosilicate site by doping the silica particle with aluminum atoms on the particle surface, and the stabilization of the aluminosilicate site is improved by the presence of an alkali metal that serves as a counterion to the negatively charged aluminum atom.

The present invention relates to a hollow silica sol comprising hollow silica particles having a space inside an outer shell and monovalent alkali metal ions, and containing monovalent alkali metal ions in a molar ratio of 7.12×10 ^-6 to 285×10 ^-6 , converted into M ₂ O (wherein M represents a monovalent alkali metal atom) with respect to SiO ₂ of the hollow silica particles, wherein the hollow silica sol has a particle diameter value (average particle diameter) obtained by dynamic light scattering after storage at 50°C for 48 hours that is within a range of 2.0 times the particle diameter value obtained by dynamic light scattering before storage.

Hollow silica particles have an outer shell of silica and a space inside the outer shell. Hollow silica is obtained by forming an outer shell mainly composed of silica on the surface of a portion corresponding to the core, called the template, in a dispersion medium, and removing the portion corresponding to the core.

Hollow silica particles are required to be stably dispersed in a dispersion medium, and the presence of silanol groups on the surface of the hollow silica particles, the presence of organic functional groups, and the presence of aluminosilicate sites doped with aluminum atoms are stabilized by providing monovalent alkali metal ions to the surface of the hollow silica particles. The silanol groups, organic functional groups, and aluminosilicate sites have polymerizable functional groups such as hydroxyl groups, and the interaction between these polymerizable functional groups leads to weak condensation (entanglement) between particles or crosslinking between particles by hydrogen bonds, leading to destabilization of the particles or an increase in the particle size. It is thought that when monovalent alkali metal ions are added to these polymerizable functional groups, the form of the hydroxyl groups changes and the destabilization factor is suppressed. These polymerizable functional groups may be destabilized by heating, and the stability of the hollow silica sol can be assessed by checking after 48 hours at 50°C.

Examples of the monovalent alkali metal ion include lithium ion, sodium ion, potassium ion, rubidium ion, and cesium ion, preferably lithium ion, sodium ion, and potassium ion, and particularly preferably sodium ion.

The content of monovalent alkali metal ions can be, in terms of the molar ratio of monovalent alkali metal ions converted into M ₂ O (where M represents a monovalent alkali metal atom) per mass of SiO ₂ of hollow silica particles in the dispersion (sol), 7.12×10 ^-6 to 285×10 ^-6 , or 7.12×10 ^-6 to 237×10 ^-6 , or 7.12×10 ^-6 to 190×10 ^-6 , or 20×10 ^-6 to 285×10 ^-6 , or 50×10 ^-6 to 285×10 ^-6 .

In addition, the content of the above monovalent alkali metal ion can be set to an amount equivalent to 15 ppm to 600 ppm, or 15 ppm to 500 ppm, or 15 ppm to 400 ppm, in terms of the molar ratio of monovalent alkali metal ion per mass of SiO ₂ of the hollow silica particles in the dispersion (sol) converted to M ₂ O (wherein M represents a monovalent alkali metal atom).

The hollow silica sol of the present invention can be set to have an average particle diameter of 20 to 150 nm as determined by a dynamic light scattering method. In addition, the particle diameter of the hollow silica sol as determined by a dynamic light scattering method after storage at 50°C for 48 hours is within 2.0 times, or within 1.5 times, or within 1.1 times, as compared to before storage. In addition, the present invention also includes a particle diameter as determined by a dynamic light scattering method after storage at 50°C for 48 hours that becomes smaller than before storage. Therefore, the lower limit can be set to 0.8 times or more, or 0.9 times or more, or 1.0 times or more.

In the present invention, the stability of the hollow silica sol can be secured by containing sodium ions in the above range, which means that the sol including hollow silica particles can contain sodium ions in the above range before being destabilized. In addition, by adding the sodium ions to the sol including destabilized hollow silica particles, the agglomerated state of the hollow silica particles can be released, and the particle size range of the hollow silica particles before agglomeration can be restored.

In the present invention, aluminum atoms can be expressed by converting aluminum present on the surface of silica particles into _Al2O3 by measuring the aluminum measured by the leaching method with an aqueous solution of at least one inorganic acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid. That is, aluminum atoms are bonded to silica particles in a ratio ( _{A )} of 100 to 20,000 _ppm / _SiO2 , or 100 to 15,000 ppm/ _SiO2 , 100 to 10,000 ppm/ _SiO2 , or 200 to 5,000 ppm/ _SiO2 , or 500 to 5,000 ppm/ _SiO2 , or 800 to 3,000 ppm/ _SiO2 , relative to the mass of SiO2 of the hollow silica _particles measured by the leaching method on the surface of the hollow silica particles. It is important to form aluminosilicate sites on the surface of silica particles when dispersing them in a solvent or resin.

Aluminum atoms present as aluminosilicate on the surface of silica particles are leached (eluted) into a structure close to aluminum salt, aluminum oxide, or aluminum hydroxide by an aqueous solution of at least one inorganic acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid, and the aluminum atoms can be measured from the solution using an ICP emission spectrometer and expressed by conversion into Al ₂ O _3. In particular, a method of leaching (eluting) using a nitric acid aqueous solution is used. The nitric acid aqueous solution used for leaching can be used in a range of pH 0.5 to 4.0, 0.5 to 3.0, 0.5 to 2.0, or 1.0 to 1.5, and typically, a nitric acid aqueous solution having a pH of 1.0 can be used. For example, 100 mL of the above nitric acid aqueous solution is added to 1 g of silica, and maintained at a temperature of 20 to 70°C or 40 to 60°C for 10 to 24 hours to elute aluminum compounds from the surface of the silica particles, which can be used as a sample for analysis.

In the present invention, the silica particle surface can be defined as a region from which an aluminum compound can be eluted by the above leaching. That is, the solvent is evaporated from a silica sol, and further, silica gel dried at 250°C is ground and crushed to obtain silica powder, 20 mL of a pH 1.0 nitric acid aqueous solution is added to 0.2 g of the silica powder, the mixture is sufficiently shaken, and the mixture is maintained in a constant temperature bath at 50°C for 17 hours. Then, centrifugal filtration is performed, and the aluminum content in the obtained filtrate is measured using an ICP emission spectrometer, and the aluminum content converted into Al ₂ O ₃ is divided by the mass of the silica powder to obtain the amount of aluminum bound to the silica particle surface (Al ₂ O ₃ /SiO ₂ ) (ppm).

In addition, even in cases where aluminosilicate is formed on the surface of silica particles, depending on the manufacturing method, aluminosilicate may be selectively formed not only on the surface but also on the inside of the silica particles. The mass of aluminum atoms present in the entire hollow silica particles, including the surface and the inside, is bonded to the silica particles in a ratio ( _{B )} of 120 to 50,000 ppm/SiO ₂ , or 500 to 20,000 ppm/SiO ₂ , or 500 to 10,000 ppm/SiO ₂ , or 1,000 to 5,000 ppm/SiO ₂ , or 1,000 to 4,000 ppm/SiO ₂ , in terms of Al 2 O 3 , to the mass of SiO ₂ of the hollow silica particles.

The ratio (A)/ratio (B), which is the ratio of aluminum present on the surface of the silica particles and throughout the silica particles, can be set in the range of 0.001 to 1.0, or 0.01 to 1.0, or 0.1 to 1.0, or 0.3 to 1.0, or 0.4 to 1.0.

By measuring the aluminum atoms present in the entire silica particles by dissolving the silica particles in an aqueous hydrofluoric acid solution, it can be expressed by converting it to _Al2O3 . That is, the aluminum atoms present in the entire silica particles as aluminosilicate can be measured using an ICP emission spectrometer from the solution by dissolving it in an aqueous hydrofluoric _acid solution, _and the aluminum atoms present in the entire silica particles can be expressed by converting it to _Al2O3 . The aqueous hydrofluoric acid solution may have a concentration that can dissolve the silica particles, and for example, a 48 mass% aqueous hydrofluoric acid solution can be used. In addition, in order to completely dissolve the silica particles, the amount of the aqueous hydrofluoric acid solution used must be equivalent to or more than the silica particles, and the molar ratio is preferably 1.1 to 1000 equivalents.

In this way, by forming aluminosilicate sites on the surface of the silica particles, the negative charge (surface charge) of the hollow silica particles present on the surface of the silica particles is measured in the range of 5 to 250 μeq/g per ₁ g, or 5 to 150 μeq/g, or 5 to 100 μeq/g, or 25 to 150 μeq/g, or 25 to 100 μeq/g in terms of SiO2.

The above hollow silica particles can be obtained as a hollow silica sol dispersed in a dispersion medium. As a sol in which hollow silica particles are dispersed in a dispersion medium, a hollow silica sol having an average particle diameter of 20 to 150 nm as determined by a dynamic light scattering method can be obtained.

Hollow silica is obtained by forming an outer shell mainly composed of silica on the surface of a portion corresponding to the core, called the so-called template, in a dispersion medium, and removing the portion corresponding to the core. In this state, it is a hollow silica aqueous sol.

The hollow silica aqueous sol thus obtained can be solvent-exchanged with an alcohol solvent as an organic solvent. The alcohol solvent is preferably an alcohol having 1 to 5 carbon atoms and possibly having an ether bond, and examples thereof include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, propylene glycol monomethyl ether, and propylene glycol monoethyl ether. Thereafter, if necessary, after coating with a silane compound, solvent-exchange can be further performed with a separate organic solvent.

In the present invention, examples of organic solvents include alcohols, ketones, ethers, amides, ureas, and esters having 1 to 10 carbon atoms.

Alcohols having 1 to 10 carbon atoms are fatty alcohols, and include first-class alcohols, second-class alcohols, and tertiary alcohols. These alcohols can also be used as polyhydric alcohols, for example, dihydric alcohols and trihydric alcohols.

As first-class alcohols, examples include methanol, ethanol, 1-propanol, 1-butanol, and 1-hexanol.

As primary secondary alcohols, examples include 2-propanol, 2-butanol, cyclohexanol, propylene glycol monomethyl ether, and propylene glycol monoethyl ether.

Examples of tertiary alcohols include tert-butyl alcohol.

Examples of dihydric alcohols include methanediol, ethylene glycol, and propylene glycol.

Examples of trivalent alcohols include glycerin.

As a ketone having 1 to 10 carbon atoms, an aliphatic ketone can be preferably used. Examples thereof include acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, and methylcyclopentanone.

As an ether having 1 to 10 carbon atoms, an aliphatic ether can be preferably used. Examples include dimethyl ether, ethyl methyl ether, diethyl ether, tetrahydrofuran, and 1,4-dioxane.

Amides having 5 to 20 carbon atoms include N-methylpyrrolidone, dimethylacetamide, and diethylacetamide.

Ureases having 5 to 20 carbon atoms include tetramethylurea and 1,3-dimethyl-2-imidazolidinone.

As an ester having 1 to 10 carbon atoms, an aliphatic ester can be preferably used. Examples thereof include methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl acrylate, ethyl acrylate, propyl acrylate, dimethyl maleate, diethyl maleate, dipropyl maleate, dimethyl adipate, diethyl adipate, and dipropyl adipate.

In the above raw material hollow silica aqueous sol and hollow silica organic solvent sol, the hollow silica particles can have an average particle diameter as measured by dynamic light scattering (DLS) of 20 to 150 nm, or 30 to 150 nm, or 40 to 150 nm, or 50 to 150 nm, or 50 to 120 nm, or 50 to 100 nm.

Additionally, the average primary particle diameter as observed by a transmission electron microscope can be in the range of 20 to 150 nm, or 30 to 150 nm, or 40 to 150 nm, or 50 to 150 nm, or 50 to 120 nm, or 50 to 100 nm.

In addition, the specific surface area (C) by the BET method (nitrogen gas adsorption method) can be set to 18 to 200 m ² /g, or 50 to 160 ^{m 2} /g, or 60 to 160 m ² /g, or 70 to 160 m ² /g, or 80 to 150 m ² /g.

Additionally, the specific surface area (D) converted from the transmission electron microscope can be set to 18 to 136 m ² /g, or 18 to 90 m ² /g, or 18 to 68 m ² /g, or 18 to 54 m ² /g, or 18 to 27 m ² /g, or 18 to 23 m ² /g.

And, the ratio of [specific surface area (C) by BET method (nitrogen gas adsorption method)]/[specific surface area (D) converted from transmission electron microscope] can be set in the range of 1.40 to 5.00, or 1.40 to 3.50, or 1.50 to 3.00, or 1.50 to 2.80. When the value of (C)/(D) is close to 1.0, it indicates a solid silica particle having no space inside the outer shell of the silica particle, and when the value of (C)/(D) exceeds 1.0, it indicates a hollow silica particle having space inside the outer shell of the silica particle.

In addition, the thickness of the outer shell of the hollow silica particles as observed by transmission electron microscopy can be manufactured in the range of 3.0 to 15.0 nm, or 4.0 to 12.0 nm, or 5.0 to 10.0 nm.

And, the refractive index of the hollow silica particles can be obtained in the range of 1.20 to 1.45, or 1.20 to 1.40, or 1.25 to 1.40.

Additionally, the hollow silica sol can be used with a concentration of SiO ₂ particles of 1 to 50 mass%, or 5 to 40 mass%, and typically 10 to 30 mass%.

The above sol can be adjusted to pH from acidic to alkaline. Adjustment to acidity is performed by adding inorganic acid or organic acid. In addition, adjustment to alkalinity is performed by adding inorganic base or organic base, and as an organic base, amine can be added for the purpose of adjusting pH and surface charge. The pH can be set to pH 1 to less than 7 on the acid side, and to pH 7 or more and 13 or less on the alkaline side.

The aqueous sol of hollow silica can be set to a range of, for example, pH 2.0 to 6.0, or pH 2.0 to 4.5 by addition of an amine, and can be adjusted to a range of, for example, pH 3.0 to 10.0, or 3.0 to 9.0 by addition of an amine.

In the case of an organic solvent sol, the above pH is the pH when the organic solvent sol and the same mass of pure water are mixed in a 1:1 ratio, and the organic solvent can be measured when an organic solvent that can be mixed with water is used. However, when performing solvent substitution with a hydrophobic organic solvent later, it is preferable to measure the pH in advance at the stage of methanol solvent sol.

For example, for hydrophilic organic solvents such as methanol sol and propylene glycol monomethyl ether sol, the dispersion medium can be measured using a solution in which pure water and the sol are mixed in a mass ratio of 1:1, and for hydrophobic organic solvents such as methyl ethyl ketone sol, the dispersion medium can be measured using a solution in which pure water, methanol, and methyl ethyl ketone sol are mixed in a mass ratio of 1:1:1.

The hollow silica organic solvent sol undergoes solvent substitution of an aqueous medium into an alcohol solvent having 1 to 5 carbon atoms, and further into an organic solvent, during which moisture may remain. In the alcohol sol stage of the hollow silica, for example, the residual moisture may be contained in the sol at 0.1 to 3.0 mass%, or 0.1 to 1.0 mass%. In addition, in the organic solvent sol stage of the hollow silica (wherein the dispersion medium is an organic solvent other than alcohol), it may be contained at 0.01 to 0.5 mass%.

Additionally, in the hollow silica organic solvent sol, the viscosity can be set in the range of 1.0 to 10.0 mPa·s.

The hollow silica sol of the present invention may have an amine added thereto.

The amine used in the present invention may be a water-soluble amine having a water solubility of 80 g/L or more, or 100 g/L or more.

In the hollow silica aqueous sol as a raw material, and the hollow silica organic solvent sol obtained by solvent substitution, amine, or amine and ammonia can be contained. The amine can be added and contained in a range of 0.001 to 10 mass%, or 0.01 to 10 mass%, or 0.1 to 10 mass% with respect to SiO ₂ of the hollow silica particles. And, the amine, or amine and ammonia can be expressed as the total nitrogen amount in the hollow silica particle organic solvent sol as these basic components, and can be contained in a range of, for example, 10 to 100,000 ppm, or 100 to 10,000 ppm, or 100 to 3,000 ppm, or 100 to 2,000 ppm, typically 200 to 2,000 ppm.

The above amines include aliphatic amines and aromatic amines, and aliphatic amines can be preferably used. At least one amine selected from the group consisting of primary amines, secondary amines, and tertiary amines having 1 to 10 carbon atoms can be used. These amines are water-soluble and at least one amine selected from the group consisting of primary amines, secondary amines, and tertiary amines having 1 to 10 carbon atoms.

For example, primary amines include monomethylamine, monoethylamine, monopropylamine, monoisopropylamine, monobutylamine, monoisobutylamine, monosecbutylamine, monotertbutylamine, monomethanolamine, monoethanolamine, monopropanolamine, monoisopropanolamine, monobutanolamine, monoisobutanolamine, monosecbutanolamine, and monotertbutanolamine.

Secondary amines include dimethylamine, diethylamine, dipropylamine, diisopropylamine, N-methylethylamine, N-ethylisobutylamine, dimethanolamine, diethanolamine, dipropanolamine, diisopropanolamine, N-methanolethylamine, N-methylethanolamine, N-ethanolisobutylamine, N-ethylisobutanolamine, etc.

Tertiary amines include trimethylamine, triethylamine, tripropylamine, triisopropylamine, tributylamine, triisobutylamine, trisecbutylamine, tri-tertbutylamine, trimethanolamine, triethanolamine, tripropanolamine, triisopropanolamine, tributanolamine, triisobutanolamine, trisecbutanolamine, tri-tertbutanolamine, tripentylamine, 3-(dimethylamino)acrylate ethyl, 2-(dimethylamino)ethyl acrylate, 2-(dimethylamino)ethyl methacrylate, 2-(diethylamino)ethyl acrylate, 2-(diethylamino)ethyl methacrylate, and the like.

The water solubility of the above amine is preferably 80 g/L or more, or 100 g/L or more. Among these amines, primary amines and secondary amines are preferable, and secondary amines are preferably used due to their low volatility and high solubility, and examples thereof include diisopropylamine and diethanolamine.

In the present invention, by containing the amine, the surface charge of the hollow silica particles can be set to 5 μeq/g or more per 1 g, or 25 μeq/g or more in terms of SiO _2. Typically, it can be set to a range of 5 to 250 μeq/g, or 25 to 250 μeq/g, or 25 to 100 μeq/g, or 25 to 80 μeq/g.

In the present invention, by adjusting the type or amount of the amine described above, it is possible to adjust the surface charge of the hollow silica particles to any desired surface charge.

In the present invention, the surface of hollow silica particles can be coated with a silane compound.

The above silane compound can be coated with a hydrolyzate of at least one silane compound selected from the group consisting of formulae (1) and (2).

In formula (1), R ¹ is an organic group having an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, a polyether group, an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, or a cyano group, and is bonded to a silicon atom by a Si-C bond, R ² represents an alkoxy group, an acyloxy group, or a halogen group, and a represents an integer from 1 to 3,

In formula (2), R ³ is an alkyl group having 1 to 3 carbon atoms, or an aryl group having 6 to 30 carbon atoms, and is bonded to a silicon atom via a Si-C bond, R ⁴ represents an alkoxy group, an acyloxy group, or a halogen group, Y represents an alkylene group, NH group, or an oxygen atom, b is an integer from 1 to 3, c is an integer from 0 or 1, and d is an integer from 1 to 3.

The above alkyl group is an alkyl group having 1 to 18 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a cyclopropyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, a cyclobutyl group, a 1-methyl-cyclopropyl group, a 2-methyl-cyclopropyl group, an n-pentyl group, a 1-methyl-n-butyl group, a 2-methyl-n-butyl group, a 3-methyl-n-butyl group, a 1,1-dimethyl-n-propyl group, a 1,2-dimethyl-n-propyl group, a 2,2-dimethyl-n-propyl group, a 1-ethyl-n-propyl group, a cyclopentyl group, a 1-methyl-cyclobutyl group, a 2-methyl-cyclobutyl group, a 3-methyl-cyclobutyl group, a 1,2-dimethyl-cyclopropyl group, 2,3-dimethyl-cyclopropyl group, 1-ethyl-cyclopropyl group, 2-ethyl-cyclopropyl group, n-hexyl group, 1-methyl-n-pentyl group, 2-methyl-n-pentyl group, 3-methyl-n-pentyl group, 4-methyl-n-pentyl group, 1,1-dimethyl-n-butyl group, 1,2-dimethyl-n-butyl group, 1,3-dimethyl-n-butyl group, 2,2-dimethyl-n-butyl group, 2,3-dimethyl-n-butyl group, 3,3-dimethyl-n-butyl group, 1-ethyl-n-butyl group, 2-ethyl-n-butyl group, 1,1,2-trimethyl-n-propyl group, 1,2,2-trimethyl-n-propyl group, 1-ethyl-1-methyl-n-propyl group, 1-Ethyl-2-methyl-n-propyl group, cyclohexyl group, 1-methyl-cyclopentyl group, 2-methyl-cyclopentyl group, 3-methyl-cyclopentyl group, 1-ethyl-cyclobutyl group, 2-ethyl-cyclobutyl group, 3-ethyl-cyclobutyl group, 1,2-dimethyl-cyclobutyl group, 1,3-dimethyl-cyclobutyl group, 2,2-dimethyl-cyclobutyl group, 2,3-dimethyl-cyclobutyl group, 2,4-dimethyl-cyclobutyl group, 3,3-dimethyl-cyclobutyl group, 1-n-propyl-cyclopropyl group, 2-n-propyl-cyclopropyl group, 1-i-propyl-cyclopropyl group, 2-i-propyl-cyclopropyl group, 1,2,2-trimethyl-cyclopropyl group, Examples thereof include, but are not limited to, a 1,2,3-trimethyl-cyclopropyl group, a 2,2,3-trimethyl-cyclopropyl group, a 1-ethyl-2-methyl-cyclopropyl group, a 2-ethyl-1-methyl-cyclopropyl group, a 2-ethyl-2-methyl-cyclopropyl group, and a 2-ethyl-3-methyl-cyclopropyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, and an octadecyl group.

In addition, the alkylene group may include an alkylene group derived from the alkyl group described above.

The above aryl group is an aryl group having 6 to 30 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, an anthracene group, and a pyrene group.

The alkenyl group is an alkenyl group having 2 to 10 carbon atoms, and includes an ethenyl group, a 1-propenyl group, a 2-propenyl group, a 1-methyl-1-ethenyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, a 2-methyl-1-propenyl group, a 2-methyl-2-propenyl group, a 1-ethylethenyl group, a 1-methyl-1-propenyl group, a 1-methyl-2-propenyl group, a 1-pentenyl group, a 2-pentenyl group, a 3-pentenyl group, a 4-pentenyl group, a 1-n-propylethenyl group, a 1-methyl-1-butenyl group, a 1-methyl-2-butenyl group, a 1-methyl-3-butenyl group, a 2-ethyl-2-propenyl group, a 2-methyl-1-butenyl group, a 2-methyl-2-butenyl group, 2-Methyl-3-butenyl group, 3-methyl-1-butenyl group, 3-methyl-2-butenyl group, 3-methyl-3-butenyl group, 1,1-dimethyl-2-propenyl group, 1-i-propylethenyl group, 1,2-dimethyl-1-propenyl group, 1,2-dimethyl-2-propenyl group, 1-cyclopentenyl group, 2-cyclopentenyl group, 3-cyclopentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, 5-hexenyl group, 1-methyl-1-pentenyl group, 1-methyl-2-pentenyl group, 1-methyl-3-pentenyl group, 1-methyl-4-pentenyl group, 1-n-butylethenyl group, 2-methyl-1-pentenyl group, Examples include, but are not limited to, 2-methyl-2-pentenyl group.

The above alkoxy group may include an alkoxy group having 1 to 10 carbon atoms, and examples thereof include, but are not limited to, a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, an s-butoxy group, a t-butoxy group, an n-pentyloxy group, a 1-methyl-n-butoxy group, a 2-methyl-n-butoxy group, a 3-methyl-n-butoxy group, a 1,1-dimethyl-n-propoxy group, a 1,2-dimethyl-n-propoxy group, a 2,2-dimethyl-n-propoxy group, a 1-ethyl-n-propoxy group, and an n-hexyloxy group.

The above acyloxy group is an acyloxy group having 2 to 10 carbon atoms, for example, a methylcarbonyloxy group, an ethylcarbonyloxy group, an n-propylcarbonyloxy group, an i-propylcarbonyloxy group, an n-butylcarbonyloxy group, an i-butylcarbonyloxy group, an s-butylcarbonyloxy group, a t-butylcarbonyloxy group, an n-pentylcarbonyloxy group, a 1-methyl-n-butylcarbonyloxy group, a 2-methyl-n-butylcarbonyloxy group, a 3-methyl-n-butylcarbonyloxy group, a 1,1-dimethyl-n-propylcarbonyloxy group, a 1,2-dimethyl-n-propylcarbonyloxy group, a 2,2-dimethyl-n-propylcarbonyloxy group, a 1-ethyl-n-propylcarbonyloxy group, an n-hexylcarbonyloxy group, a 1-methyl-n-pentylcarbonyloxy group, Examples include, but are not limited to, 2-methyl-n-pentylcarbonyloxy group.

The above halogen groups include fluorine, chlorine, bromine, iodine, etc.

As an organic group having a polyether group, a polyetherpropyl group having an alkoxy group can be mentioned. For example, (CH ₃ O) ₃ SiC ₃ H ₆ (OC ₂ H ₄ )nOCH ₃ can be mentioned. n can be used in the range of 1 to 100, or 1 to 10.

Organic groups having an epoxy group include, for example, a 2-(3,4-epoxycyclohexyl)ethyl group, a 3-glycidoxypropyl group, etc.

The above (meth)acryloyl group refers to both an acryloyl group and a methacryloyl group. Examples of organic groups having a (meth)acryloyl group include a 3-methacryloxypropyl group, a 3-acryloxypropyl group, and the like.

An example of an organic group having a mercapto group is a 3-mercaptopropyl group.

Examples of the organic group having an amino group include 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, and the like.

An example of an organic group having a ureido group is a 3-ureidopropyl group.

An example of an organic group having a cyano group is a 3-cyanopropyl group.

A compound capable of forming a trimethylsilyl group on the surface of silica particles according to the above formula (2) is preferred.

Examples of these compounds are as follows:

[Chemical formula 2]

In the above formula, R ¹² is an alkoxy group, and examples thereof include a methoxy group and an ethoxy group. The silane compound may be a silane compound manufactured by Shin-Etsu Chemical Co., Ltd.

This is a process for covering the surface of silica particles with the silane compound by a siloxane bond through a reaction between a hydroxyl group on the surface of silica particles, for example, a silanol group in the case of silica particles, and the silane compound. The reaction temperature can be performed at a temperature ranging from 20°C to the boiling point of the dispersion medium, for example, in the range of 20°C to 100°C. The reaction time can be approximately 0.1 to 6 hours.

The above silane compound is added to the silica sol as a coating amount on the surface of the silica particles, and the silane compound can be coated on the surface of the silica particles by adding an amount equivalent to a coating amount in which the number of silicon atoms in the silane compound is 0.1/nm ² to 6.0/nm ² .

The hydrolysis of the above silane compound requires water, and if it is a sol of an aqueous solvent, the aqueous solvent is used. When the aqueous medium is solvent-exchanged with an organic solvent, the moisture remaining in the solvent can be used. For example, moisture existing at 0.01 to 1 mass% can be used. In addition, the hydrolysis can be performed using a catalyst or without a catalyst.

When performed without a catalyst, the silica particle surface exists on the acid side, and when using a catalyst, metal chelate compounds, organic acids, inorganic acids, organic bases, and inorganic bases can be used as hydrolysis catalysts. Examples of metal chelate compounds as hydrolysis catalysts include triethoxy mono(acetylacetonate)titanium, triethoxy mono(acetylacetonate)zirconium, etc. Organic acids as hydrolysis catalysts include, for example, acetic acid and oxalic acid. Inorganic acids as hydrolysis catalysts include, for example, hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, and phosphoric acid. Organic bases as hydrolysis catalysts include, for example, pyridine, pyrrole, piperazine, and quaternary ammonium salts. Inorganic bases as hydrolysis catalysts include, for example, ammonia, sodium hydroxide, and potassium hydroxide.

The organic acid is at least one organic acid selected from the group consisting of divalent aliphatic carboxylic acids, aliphatic oxycarboxylic acids, amino acids, and chelating agents. The divalent aliphatic carboxylic acids are oxalic acid, malonic acid, and succinic acid. The aliphatic oxycarboxylic acids are glycolic acid, lactic acid, malic acid, tartaric acid, and citric acid. The amino acids are glycine, alanine, valine, leucine, serine, and trionine. The chelating agent includes ethylenediaminetetraacetic acid, L-aspartic acid-N,N-diacetic acid, and diethylenetriamineoacetic acid. The organic acid salt includes alkali metal salts, ammonium salts, and amine salts of the above organic acids. The alkali metal includes sodium and potassium.

In the present invention, a film-forming composition comprising the hollow silica organic solvent sol and an organic resin or polysiloxane is obtained.

An organic resin or polysiloxane is selected and mixed with a thermosetting or photocurable resin to obtain a film-forming composition. In addition, a curing agent such as an amine-based curing agent, an acid anhydride-based curing agent, a radical generator-based curing agent (thermal radical generator, photoradical generator), or an acid generator-based curing agent (thermal acid generator, or photoacid generator) can be included to form a cured product.

The composition can form a cured product by applying or filling a film-forming composition containing an organic resin or polysiloxane and a curing agent onto a substrate, and heating, light irradiation, or a combination thereof. The organic resin and polysiloxane (curable resin) can be a resin having a functional group such as an epoxy group or a (meth)acryloyl group, or an isocyanate-based resin. For example, a photocurable multifunctional acrylate can be preferably used.

Polyfunctional acrylates include polyfunctional acrylates having two, three, four, or more functional groups in the molecule, and examples thereof include neopentyl glycol di(meth)acrylate, trimethylol propane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

These multifunctional acrylates may be described below.

[Chemical Formula 3]

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical formula 6]

The film-forming composition of the present invention may contain a surfactant (leveling agent).

As surfactants (leveling agents), anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, and silicone surfactants can be used. The surfactant (leveling agent) can be added in the range of 0.01 to 5 phr or 0.01 to 1 phr to the organic resin or polysiloxane.

Examples of the anionic surfactant used in the present invention include sodium salts and potassium salts of fatty acids, alkylbenzene sulfonates, higher alcohol sulfate ester salts, polyoxyethylene alkyl ether sulfates, α-sulfo fatty acid esters, α-olefin sulfonates, monoalkyl phosphate ester salts, and alkane sulfonates.

For example, alkylbenzene sulfonates include sodium salts, potassium salts, and lithium salts, and include sodium C10~C16 alkylbenzene sulfonate, C10~C16 alkylbenzene sulfonic acid, and sodium alkylnaphthalene sulfonate.

Higher alcohol sulfate ester salts include sodium dodecyl sulfate (sodium lauryl sulfate), triethanolamine lauryl sulfate, and triethanolammonium lauryl sulfate, all of which have 12 carbon atoms.

Polyoxyethylene alkyl ether sulfates include sodium polyoxyethylene styrenated phenyl ether sulfate, ammonium polyoxyethylene styrenated phenyl ether sulfate, sodium polyoxyethylene decyl ether sulfate, ammonium polyoxyethylene decyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, ammonium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene tridecyl ether sulfate, and sodium polyoxyethylene oleyl cetyl ether sulfate.

α-Olefin sulfonate salts include sodium α-olefin sulfonate, etc.

Examples of alkane sulfonates include sodium 2-ethylhexyl sulfate.

Examples of the cationic surfactant used in the present invention include alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, and amine salt-based agents.

Alkyltrimethylammonium salts are quaternary ammonium salts, and have chloride or bromide as counter ions. Examples include dodecyltrimethylammonium chloride, cetyltrimethylammonium chloride, palm alkyltrimethylammonium chloride, and alkyl(C16-18)trimethylammonium chloride.

Dialkyl dimethyl ammonium salts have two main chains that become lipophilic and two methyl groups. Examples thereof include bis(hydrogenated tallow) dimethyl ammonium chloride. Examples thereof include didecyl dimethyl ammonium chloride, didecyl dimethyl ammonium chloride, dihydrogenated tallow alkyl dimethyl ammonium chloride, and dialkyl (C14-18) dimethyl ammonium chloride.

Alkyl dimethyl benzylammonium salts are quaternary ammonium salts having one lipophilic main chain, two methyl groups, and a benzyl group, and examples thereof include benzauconium chloride. An example thereof includes alkyl (C8-18) dimethyl benzylammonium chloride.

Amine salts are those in which the hydrogen atoms of ammonia are replaced with one or more hydrocarbon groups, and examples thereof include N-methylbishydroxyethylamine fatty acid ester hydrochloride.

The amphoteric surfactants used in the present invention include N-alkyl-β-alanine type alkylamino fatty acid salts, alkyl carboxy betaine type alkyl betaines, and N,N-dimethyldodecylamine oxide type alkyl amine oxides. Examples of these include lauryl betaine, stearyl betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, and lauryl dimethylamine oxide.

The nonionic surfactant used in the present invention is selected from polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, alkyl glucosides, polyoxyethylene fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and fatty acid alkanolamides. For example, examples of the polyoxyethylene alkyl ether include polyoxyethylene dodecyl ether (polyoxyethylene lauryl ether), polyoxyalkylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyalkylene tridecyl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene behenyl ether, polyoxyethylene-2-ethylhexyl ether, and polyoxyethylene isodecyl ether.

Polyoxyethylene alkylphenol ethers include polyoxyethylene styrenated phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene distyrenated phenyl ether, and polyoxyethylene tribenzyl phenyl ether.

Alkyl glucosides include decyl glucoside and lauryl glucoside.

Polyoxyethylene fatty acid esters include polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, polyethylene glycol distearate, polyethylene glycol dioleate, and polypropylene glycol dioleate.

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

Polyoxyethylene sorbitan fatty acid esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan triisostearate.

In addition, fatty acid alkanolamides include palm oil fatty acid diethanolamide, beef tallow fatty acid diethanolamide, lauric acid diethanolamide, and oleic acid diethanolamide.

In addition, examples thereof include polyoxyalkyl ethers such as polyoxyethylene polyoxypropylene glycol, polyoxyethylene fatty acid ester, or polyoxyalkyl glycol, polyoxyethylene hydrogenated castor oil ether, sorbitan fatty acid ester alkyl ether, alkyl polyglucoside, sorbitan monooleate, sucrose fatty acid ester, etc.

A silicone surfactant can be used. A silicone surfactant is a compound having a repeating unit containing a siloxane bond in the main chain. The weight average molecular weight of the silicone surfactant can be used in the range of 500 to 50,000. These may be modified silicone surfactants, and may include a structure in which an organic group is introduced into the side chain and/or terminal of polysiloxane. The organic group may include an amino group, an epoxy group, an alicyclic epoxy group, a carbinol group, a mercapto group, a carboxyl group, an aliphatic ester group, an aliphatic amide group, and a polyether group. Silicone surfactants include product names such as Toray Silicone DC3PA, Toray Silicone SH7PA, Toray Silicone DC11PA, Toray Silicone SH21PA, Toray Silicone SH28PA, Toray Silicone SH29PA, Toray Silicone SH30PA, and Toray Silicone SH8400 (all manufactured by Toray/Dow Corning Co., Ltd.), Silwet l-77, L-7280, L-7001, L-7002, L-7200, L-7210, L-7220, L-7230, L7500, L-7600, L-7602, L-7604, L-7605, L-7622, L-765 7, L-8500, L-8610 (all manufactured by Momentive Performance Materials Co., Ltd.), KP-341, KF-6001, Examples include KF-6002 (manufactured by Shin-Etsu Silicone Co., Ltd.), BYK307, BYK323, and BYK330 (manufactured by Big Chemie Co., Ltd.). For example, as a polyether-modified silicone, the product name L-7001 (manufactured by DOWSIL Co., Ltd.) can be suitably used.

In the present invention, a film-forming composition comprising the organic solvent sol and an organic resin or polysiloxane is obtained. The film-forming composition can be made into a film-forming composition comprising hollow silica particles and an organic resin by removing the organic solvent in the organic solvent sol.

In the case of a thermosetting film-forming composition in the above film-forming composition, it is possible to add a thermosetting agent in a range of 0.01 to 50 phr, or 0.01 to 10 phr, to a resin containing a functional group such as an epoxy group or a (meth)acryloyl group. For example, the thermosetting agent may be contained in a ratio of 0.5 to 1.5 equivalents, preferably 0.8 to 1.2 equivalents, to a functional group such as an epoxy group or a (meth)acryloyl group. The equivalent amount of the thermosetting agent to the curable resin is expressed as an equivalent ratio of the thermosetting agent to the functional group.

Examples of the thermosetting agent include phenol resins, amine curing agents, polyamide resins, imidazoles, polymercaptans, acid anhydrides, thermal radical generators, and thermal acid generators. In particular, radical generator-based curing agents, acid anhydride-based curing agents, and amine-based curing agents are preferable.

Although these thermosetting agents can be used by dissolving them in a solvent even if they are solid, the evaporation of the solvent causes a decrease in the density of the cured product, and the formation of pores causes a decrease in strength and a decrease in water resistance, so it is preferable that the curing agent itself be liquid at room temperature and pressure.

Examples of phenol resins include phenol novolac resin and cresol novolac resin.

Examples of amine curing agents include piperidine, N,N-dimethylpiperazine, triethylenediamine, 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine, 2-(dimethylaminomethyl)phenol, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, di(1-methyl-2-aminocyclohexyl)methane, menthanediamine, isophoronediamine, diaminodicyclohexylmethane, 1,3-diaminomethylcyclohexane, xylenediamine, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, 3,3'-diethyl-4,4'-diaminodiphenylmethane, and diethyltoluenediamine. Among these, liquid diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, di(1-methyl-2-aminocyclohexyl)methane, mensenediamine, isophoronediamine, diaminodicyclohexylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, diethyltoluenediamine, etc. can be preferably used.

Polyamide resin is a polyamideamine that is produced by the condensation of dimer acid and polyamine and has primary amine and secondary amine in the molecule.

Examples of imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, and epoxyimidazole adducts.

Polymercaptan is, for example, one in which a mercaptan group exists at the end of a polypropylene glycol chain or one in which a mercaptan group exists at the end of a polyethylene glycol chain, and is preferably in a liquid state.

As the acid anhydride curing agent, anhydrides of compounds having multiple carboxyl groups in one molecule are preferable. Examples of these acid anhydride curing agents include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bistrimellitate, glycerol tristrimellitate, maleic anhydride, tetrahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, endomethylene tetrahydrophthalic anhydride, methyl endomethylene tetrahydrophthalic anhydride, methyl butenyl tetrahydrophthalic anhydride, dodecenyl succinic anhydride, hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, succinic anhydride, methylcyclohexenedicarboxylic anhydride, and chlorendic anhydride.

Sulfonium salts and phosphonium salts can be used as thermal oxidizers, and sulfonium salts are preferably used. For example, the following compounds can be exemplified.

[Chemical formula 7]

R may be an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 20 carbon atoms, and an alkyl group having 1 to 12 carbon atoms is particularly preferred.

Among these, methyl tetrahydrophthalic anhydride, methyl-5-norbornene-2,3-dicarboxylic anhydride (methyl nadic anhydride, methyl heimic anhydride), hydrogenated methyl nadic anhydride, methyl butenyl tetrahydrophthalic anhydride, dodecenyl succinic anhydride, methyl hexahydrophthalic anhydride, and a mixture of methyl hexahydrophthalic anhydride and hexahydrophthalic anhydride are preferable, which are liquid at room temperature and pressure. These liquid anhydrides have a viscosity of about 10 mPa·s to 1000 mPa·s when measured at 25°C.

Examples of the thermal radical generators include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-methylpropionic acid)dimethyl, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, and benzoyl peroxide. These can be obtained from Tokyo Kasei Kogyo Co., Ltd.

In addition, when obtaining the above-mentioned cured product, a curing agent may be appropriately used in combination. As the curing agent, an organic phosphorus compound such as triphenylphosphine or tributylphosphine, a quaternary phosphonium salt such as ethyltriphenylphosphonium bromide or methyltriphenylphosphonium phosphate diethyl, a quaternary ammonium salt such as 1,8-diazabicyclo(5,4,0)undecan-7-ene, a salt of 1,8-diazabicyclo(5,4,0)undecan-7-ene and octylic acid, zinc octylate, or tetrabutylammonium bromide can be exemplified. These curing agents can be contained in a proportion of 0.001 to 0.1 part by mass relative to 1 part by mass of the curing agent.

The composition is obtained by mixing a resin, a hardener, and, if necessary, a hardening agent to obtain a thermosetting varnish. This mixing can be performed in a reaction vessel using a stirring blade or a kneader.

Mixing is performed by a heating mixing method and is performed at a temperature of 60°C to 100°C for 0.5 to 1 hour.

The obtained curable film-forming composition is a thermosetting coating composition and has an appropriate viscosity for use as, for example, a liquid encapsulating material. The liquid thermosetting film-forming composition can be prepared at an arbitrary viscosity and is used as a transparent encapsulating material for LEDs and the like by a casting method, a potting method, a dispenser method, a printing method, or the like, so that partial encapsulation is possible at an arbitrary location. The liquid thermosetting composition is directly mounted on an LED and the like in a liquid state by the above-described method, and then dried and cured to obtain an epoxy resin cured body.

A thermosetting film-forming composition (thermosetting coating composition) is applied to a substrate and heated at a temperature of 80 to 200°C to obtain a cured product.

In the case of the photocurable resin composition in the film-forming composition above, it is possible to add a photocurable agent (photoradical generator, photoacid generator) in the range of 0.01 to 50 phr, or 0.01 to 10 phr, to the resin containing a functional group such as an epoxy group or a (meth)acryloyl group. For example, the photocurable agent (photoradical generator, photoacid generator) can be contained in a ratio of 0.5 to 1.5 equivalents, preferably 0.8 to 1.2 equivalents, to the functional group such as an epoxy group or a (meth)acryloyl group. The equivalent amount of the photocurable agent to the curable resin is expressed as the equivalent ratio of the photocurable agent to the functional group.

The photoradical generator is not particularly limited as long as it generates radicals directly or indirectly by light irradiation.

Examples of the photoradical generator include imidazole compounds, diazo compounds, bisimidazole compounds, N-arylglycine compounds, organic azide compounds, titanocene compounds, aluminate compounds, organic peroxides, N-alkoxypyridinium salt compounds, and thioxanthone compounds, as photoradical polymerization initiators. Examples of the azide compounds include p-azidebenzaldehyde, p-azideacetophenone, p-azidebenzoic acid, p-azidebenzalacetophenone, 4,4'-diazidechalcone, 4,4'-diazidediphenylsulfide, and 2,6-bis(4'-azidebenzal)-4-methylcyclohexanone. Examples of the diazo compounds include 1-diazo-4-N,N-dimethylaminobenzene chloride, and 1-diazo-4-N,N-diethylaminobenzeneborofluoride. Examples of the bisimidazole compounds include 2,2'-bis(o-chlorophenyl)-4,5,4',5'-tetrakis(3,4,5-trimethoxyphenyl)1,2'-bisimidazole, and 2,2'-bis(o-chlorophenyl)4,5,4',5'-tetraphenyl-1,2'-bisimidazole. Titanocene compounds include dicyclopentadienyl-titanium-dichloride, dicyclopentadienyl-titanium-bisphenyl, dicyclopentadienyl-titanium-bis(2,3,4,5,6-pentafluorophenyl), dicyclopentadienyl-titanium-bis(2,3,5,6-tetrafluorophenyl), dicyclopentadienyl-titanium-bis(2,4,6-trifluorophenyl), dicyclopentadienyl-titanium-bis(2,6-difluorophenyl), dicyclopentadienyl-titanium-bis(2,4-difluorophenyl), bis(methylcyclopentadienyl)-titanium-bis(2,3,4,5,6-pentafluorophenyl), bis(methylcyclopentadienyl)-titanium-bis(2,3,5,6-tetrafluorophenyl), Examples thereof include bis(methylcyclopentadienyl)-titanium-bis(2,6-difluorophenyl), and dicyclopentadienyl-titanium-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl).

Further examples of photoradical generators include 1,3-di(tert-butyldioxycarbonyl)benzophenone, 3,3',4,4'-tetrakis(tert-butyldioxycarbonyl)benzophenone, 3-phenyl-5-isoxazolone, 2-mercaptobenzimidazole, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone.

These photoradical polymerization agents can be obtained, for example, as Irgacure TPO (ingredient: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) (formula (c1-1-1)) manufactured by BASF, Omnirad 819 (ingredient: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide) (formula (c1-1-2) manufactured by IGM RESINS, Irgacure 184 (ingredient: 1-hydroxycyclohexylphenyl ketone) (formula (c1-1-3) manufactured by IGM RESINS.

[Chemical formula 8]

There are no particular limitations on the photoacid generator as long as it generates acid directly or indirectly by light irradiation.

Specific examples of photoacid generators include triazine compounds, acetophenone derivative compounds, disulfone compounds, diazomethane compounds, sulfonic acid derivative compounds, onium salts such as iodonium salts, sulfonium salts, phosphonium salts, and selenium salts, metallocene complexes, and iron arene complexes.

The onium salt used as the photoacid generator is an iodonium salt, for example, diphenyliodonium chloride, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium mesylate, diphenyliodonium tosylate, diphenyliodonium bromide, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluoroantimonate, diphenyliodonium hexafluoroarsenate, bis(p-tert-butylphenyl)iodonium hexafluorophosphate, bis(p-tert-butylphenyl)iodonium mesylate, bis(p-tert-butylphenyl)iodonium tosylate, bis(p-tert-butylphenyl)iodonium trifluoromethanesulfonate, bis(p-tert-butylphenyl)iodonium tetrafluoroborate, bis(p-tert-butylphenyl)iodonium chloride, Examples thereof include bis(alkylphenyl)iodonium salts such as bis(p-chlorophenyl)iodonium chloride, bis(p-chlorophenyl)iodonium tetrafluoroborate, and bis(4-t-butylphenyl)iodonium hexafluorophosphate, alkoxycarbonylalkoxy-trialkylaryliodonium salts (e.g., 4-[(1-ethoxycarbonyl-ethoxy)phenyl]-(2,4,6-trimethylphenyl)-iodonium hexafluorophosphate), and bis(alkoxyaryl)iodonium salts (e.g., bis(alkoxyphenyl)iodonium salts such as (4-methoxyphenyl)phenyliodonium hexafluoroantimonate).

As sulfonium salts, triphenylsulfonium chloride, triphenylsulfonium bromide, tri(p-methoxyphenyl)sulfonium tetrafluoroborate, tri(p-methoxyphenyl)sulfonium hexafluorophosphonate, tri(p-ethoxyphenyl)sulfonium tetrafluoroborate, triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, etc., triphenylsulfonium salts, (4-phenylthiophenyl)diphenylsulfonium hexafluoroantimonate, (4-phenylthiophenyl)diphenylsulfonium hexafluorophosphate, Examples of sulfonium salts include bis[4-(diphenylsulfonio)phenyl]sulfide-bis-hexafluoroantimonate, bis[4-(diphenylsulfonio)phenyl]sulfide-bis-hexafluorophosphate, and (4-methoxyphenyl)diphenylsulfonium hexafluoroantimonate.

Examples of phosphonium salts include triphenylphosphonium chloride, triphenylphosphonium bromide, tri(p-methoxyphenyl)phosphonium tetrafluoroborate, tri(p-methoxyphenyl)phosphonium hexafluorophosphonate, tri(p-ethoxyphenyl)phosphonium tetrafluoroborate, 4-chlorobenzenediazonium hexafluorophosphate, and benzyltriphenylphosphonium hexafluoroantimonate.

Examples include selenium salts such as triphenylselenium hexafluorophosphate, and metallocene complexes such as (η5 or η6-isopropylbenzene)(η5-cyclopentadienyl)iron(II) hexafluorophosphate.

Additionally, the following compounds can be used as photo-generators.

[Chemical formula 9]

[Chemical Formula 10]

[Chemical Formula 11]

[Chemical Formula 12]

[Chemical Formula 13]

[Chemical Formula 14]

[Chemical Formula 15]

[Chemical Formula 16]

[Chemical Formula 17]

As photoacid generators, sulfonium salt compounds and iodonium salt compounds are preferable. Their anionic species include CF ₃ SO ₃ ^- , C ₄ F ₉ SO ₃ ^- , C ₈ F ₁₇ SO ₃ ^- , camphorsulfonic acid anion, tosylate anion, BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- and SbF ₆ ^- . In particular, anionic species such as phosphorus hexafluoride and antimony hexafluoride that exhibit strong acidity are preferable.

The film-forming composition of the present invention may contain conventional additives as needed. Such additives include, for example, pigments, colorants, thickeners, sensitizers, anti-foaming agents, coating-improving agents, lubricants, stabilizers (antioxidants, heat stabilizers, light stabilizers, etc.), plasticizers, dissolution accelerators, fillers, antistatic agents, etc. These additives may be used alone or in combination of two or more.

Examples of methods for applying the film-forming composition of the present invention include flow coating, spin coating, spray coating, screen printing, casting, bar coating, curtain coating, roll coating, gravure coating, dipping, and slitting.

In the present invention, a photocoating composition (film-forming composition) can be applied onto a substrate and cured by light irradiation. Additionally, heating can be performed before or after light irradiation.

The thickness of the coating film can be selected from a range of about 0.01 μm to 10 mm, depending on the intended use of the cured product. For example, when used as a photoresist, it can be about 0.05 to 10 μm (especially 0.1 to 5 μm), when used as a printed wiring board, it can be about 5 μm to 5 mm (especially 100 μm to 1 mm), and when used as an optical thin film, it can be about 0.1 to 100 μm (especially 0.3 to 50 μm).

When obtaining a transparent film, the visible light transmittance of the film can be 80% or more, or 90% or more, typically 90 to 96%.

When using a photoacid generator, the irradiating or exposing light may be, for example, gamma rays, X-rays, ultraviolet rays, visible light, etc., and is usually visible light or ultraviolet rays, particularly ultraviolet rays in many cases. The wavelength of the light is, for example, about 150 to 800 nm, preferably about 150 to 600 nm, and more preferably about 150 to 400 nm. The irradiating light dose varies depending on the thickness of the coating film, and may be, for example, about 2 to 20,000 mJ/cm ² , and preferably about 5 to 5,000 mJ/cm ² . The light source can be selected according to the type of light to expose, and for example, in the case of ultraviolet rays, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a deuterium lamp, a halogen lamp, a laser light (helium-cadmium laser, excimer laser, etc.) can be used. The curing reaction of the composition progresses by such light irradiation.

When a thermal acid generator is used or when a photoacid generator is used, heating of the coating film, which is performed as needed after light irradiation, is performed at, for example, about 60 to 350°C, preferably about 100 to 300°C. The heating time can be selected from a range of 3 seconds or more (for example, about 3 seconds to 5 hours), and can be performed for, for example, about 5 seconds to 2 hours, preferably about 20 seconds to 30 minutes, and usually about 1 minute to 3 hours (for example, about 5 minutes to 2.5 hours).

Furthermore, when forming a pattern or image (for example, when manufacturing a printed wiring board, etc.), the film formed on the substrate may be subjected to pattern exposure, and this pattern exposure may be performed by scanning laser light or by irradiating with light through a photomask. By developing (or dissolving) the unirradiated area (unexposed area) created by such pattern exposure with a developer, a pattern or image can be formed.

An alkaline aqueous solution or an organic solvent can be used as the developer.

Examples of alkaline aqueous solutions include aqueous solutions of alkali metal hydroxides such as potassium hydroxide, sodium hydroxide, potassium carbonate, and sodium carbonate; aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline; and aqueous solutions of amines such as ethanolamine, propylamine, and ethylenediamine.

The above alkaline developer is generally an aqueous solution of 10 mass% or less, and preferably an aqueous solution of 0.1 to 3.0 mass% is used. Furthermore, alcohols or surfactants may be added to the developer and used, and each of these is preferably used in an amount of 0.05 to 10 mass parts per 100 mass parts of the developer.

Among these, a 0.1 to 2.38 mass% aqueous solution of tetramethylammonium hydroxide can be used.

In addition, as the organic solvent as the developer, it is possible to use a general organic solvent, and examples thereof include acetone, acetonitrile, toluene, dimethylformamide, methanol, ethanol, isopropanol, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether, propylene glycol butyl ether, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, propylene glycol butyl ether acetate, ethyl lactate, cyclohexanone, etc., and these can be used as one type or a mixture of two or more types. In particular, propylene glycol methyl ether, propylene glycol methyl ether acetate, ethyl lactate, etc. can be preferably used.

In the present invention, in order to improve adhesion to the substrate after development, an adhesion accelerator may be added. These adhesion promoters include chlorosilanes such as trimethylchlorosilane, dimethylvinylchlorosilane, methyldiphenylchlorosilane, and chloromethyldimethylchlorosilane; alkoxysilanes such as trimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane, dimethylvinylethoxysilane, diphenyldimethoxysilane, and phenyltriethoxysilane; silazanes such as hexamethyldisilazane, N,N'-bis(trimethylsilyl)urea, dimethyltrimethylsilylamine, and trimethylsilylimidazole; silanes such as vinyltrichlorosilane, 3-chloropropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-(N-piperidinyl)propyltrimethoxysilane; Examples thereof include heterocyclic compounds such as benzotriazole, benzimidazole, indazole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, urazole, thiouracil, mercaptoimidazole, and mercaptopyrimidine; ureas such as 1,1-dimethylurea and 1,3-dimethylurea; and thiourea compounds. One or two or more of the above adhesion promoters can be used in combination. The amount of these adhesion promoters to be added is usually 18 mass% or less, preferably 0.0008 to 9 mass%, and more preferably 0.04 to 9 mass%, based on the solid content.

The present invention may contain a sensitizer. Examples of sensitizers that can be used include anthracene, phenothiazene, perylene, thioxanthone, benzophenonethioxanthone, and the like. Furthermore, examples of sensitizing dyes include thiopyrylium salt-based pigments, merocyanine-based pigments, quinoline-based pigments, styrylquinoline-based pigments, ketocoumarin-based pigments, thioxanthene-based pigments, xanthene-based pigments, oxonol-based pigments, cyanine-based pigments, rhodamine-based pigments, and pyrylium salt-based pigments. An anthracene-based sensitizer is particularly preferable, and when used in combination with a cationic curing catalyst (radiosensitive cationic polymerization initiator), the sensitivity is dramatically improved and it also has a radical polymerization initiation function, and in the hybrid type that uses the cationic curing system and the radical curing system of the present invention in combination, the catalyst species can be simplified. As specific anthracene compounds, dibutoxyanthracene, dipropoxyanthraquinone, etc. are effective. The amount of the sensitizer added is 0.01 to 20 mass%, preferably 0.01 to 10 mass%, based on the solid content.

It is possible to photo-cure or thermally cure the composition of the present invention using a photo-radical generator, a thermal radical generator, a photoacid generator, or a thermal acid generator. In the case of using a photoacid generator or a thermal acid generator, for example, a curing agent for epoxy commonly used (e.g., an amine or an acid anhydride) is not used, or even if it is used, the content thereof is extremely low, so that the preservation stability of the composition is improved.

The composition was found to be applicable to photocationic polymerization. It has a higher curing speed than conventional liquid epoxy compounds (e.g., alicyclic epoxy compounds having an epoxycyclohexyl ring). Since the curing speed is fast, it is possible to reduce the amount of acid generator added or to use a weak acid type acid generator. Reduction of acid generator is important for preventing metal corrosion because acid-active species may remain even after UV irradiation. Since the curing speed is fast, thick film curing is possible.

Curing by UV irradiation can be applied to materials (substrates) that are weak to heat.

The thermosetting material and photocurable material using the film-forming composition of the present invention have the characteristics of low permittivity, low dielectric tangent, fast curing, high transparency, and small curing shrinkage, and can be used for covering or bonding electronic components, optical components (anti-reflection films), and precision mechanical components. For example, they can be used for bonding optical components such as lenses for mobile phones or cameras, light-emitting diodes (LEDs), and semiconductor lasers (LDs), liquid crystal panels, biochips, lenses or prisms for cameras, magnetic components for hard disks for PCs, CD and DVD player pickups (parts that input optical information reflected from a disk), cones and coils for speakers, magnets for motors, circuit boards, electronic components, and internal engine components for automobiles.

As a hard coat material for surface protection of automobile bodies, lamps or telephone products, building materials, plastics, etc., it can be applied to, for example, automobile and motorcycle bodies, headlight lenses or mirrors, plastic lenses for glasses, mobile phones, game consoles, optical films, ID cards, etc.

Examples of ink materials for printing on metals such as aluminum, plastics, etc. include ink for printing on cards such as credit cards and membership cards, switches and keyboards of telephone products or OA devices, and ink for inkjet printers for CDs, DVDs, etc.

Examples include technology for making complex three-dimensional objects by curing resin in combination with 3D CAD, application to stereolithography such as model making for industrial products, and application to coating and bonding of optical fibers, optical waveguides, and thick film resists.

In addition, the film-forming composition of the present invention can be suitably used as an insulating resin for electronic materials such as an antireflection film, a semiconductor encapsulating material, an adhesive for electronic materials, a printed wiring substrate material, an interlayer insulating film material, a buffer coat agent for semiconductors, an enamel insulating material, an encapsulating material for power modules, or an insulating resin used in high-voltage devices such as generator coils, transformer coils, and gas-insulated switchgear.

The hollow silica sol of the present invention can be manufactured by including the following processes (I) to (II).

(I) Process: Process for preparing hollow silica sol;

(II) Process: A hollow silica sol can be obtained by a process of adjusting the molar ratio of monovalent alkali metal ions to SiO ₂ of the hollow silica particles in the hollow silica sol of the process (I) to 7.12×10 ^-6 to 285×10 ^-6 , converted into M ₂ O (where M represents a monovalent alkali metal atom).

In the above process (II), it is preferable to use sodium ion as the monovalent alkali metal ion.

In the above process (II), the sodium ion content can be adjusted by contacting the hollow silica sol obtained in the process (I) with a cation exchange resin, or by adding a sodium source. In the above process (II), the sodium source added is sodium hydroxide, and it is preferable to add it as a sodium hydroxide aqueous solution.

The dispersion medium of process (I) and process (II) can use water, alcohol having 1 to 10 carbon atoms, ketone, ether, amide, urea, or ester. These dispersion mediums can be exemplified by the solvents described above.

In the present invention, at least one process selected from the following (i) to (iv) may be added to the above process (I), process (II), or both processes.

(i): Adding amine to hollow silica sol,

(ii): Adding sodium aluminate as an aluminum source and heating to form aluminosilicate sites in hollow silica particles;

(iii): Replacing the dispersion medium with another dispersion medium;

(iv): A method may further include coating hollow silica particles with at least one silane compound selected from the group consisting of formulae (1) and (2).

And in the present invention, a method for stabilizing a hollow silica sol including hollow silica particles having a space inside an outer shell can be provided, by adding a monovalent alkali metal ion in a molar ratio of _7.12 ×10 ^-6 to 285×10 ^-6 , converted to M ₂ O (wherein M represents a monovalent alkali metal atom), to a hollow silica sol having a dynamic light scattering particle diameter value increased compared to the dynamic light scattering particle diameter at the time of manufacturing, to lower the increased dynamic light scattering particle diameter value. In the stabilization method, the monovalent alkali metal ion can utilize sodium ion.

(ii) The hollow silica sol of the process is a process in which 0.0001 to 0.5 g of an aluminum compound is added per 1 g of hollow silica particles to an aqueous sol, and heating is performed at 40 to 260°C for 0.1 to 24 hours. The amount of the aluminum compound added per 1 g of hollow silica particles in the process (ii) can be in the range of 0.0001 to 0.5 g, or 0.001 to 0.1 g, or 0.001 to 0.05 g. And (ii) the heating temperature in the process is 40 to 260°C, or 50 to 260°C, or 60 to 240°C, but in the case of non-aqueous heat treatment, it is used at less than 40 to 100°C, or less than 50 to 100°C, or less than 60 to 100°C, and in the case of hydrothermal treatment, it can be performed at 100 to 260°C, or 150 to 240°C. (ii) The heating time in the process can be performed 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.

(I) The hollow silica particles used in the process have an outer shell of silica and a space on the inside of the outer shell. The hollow silica is obtained by forming an outer shell mainly composed of silica on the surface of a portion corresponding to the core, called a template, in an aqueous dispersion medium, and removing the portion corresponding to the core. The template may be a method using an organic substance (e.g., a hydrophilic organic resin particle such as polyethylene glycol, polystyrene, or polyester) or a method using an inorganic substance (e.g., a hydrophilic inorganic compound particle such as calcium carbonate or sodium aluminate).

(I) The hollow silica aqueous sol used as a raw material in the process may be a non-aqueous heat-treated hollow silica aqueous sol that has undergone a heating temperature of less than 100°C in an aqueous medium, for example, less than 20 to less than 100°C, or less than 40 to less than 100°C, or less than 50 to less than 100°C.

In addition, the hollow silica aqueous sol used in the (I) process may be a hollow silica aqueous sol that has been heat-treated in an aqueous medium at a heating temperature of 100°C to 240°C, or 110 to 240°C.

The hollow silica sol of the raw material used in the present invention can be a non-thermal treatment hollow silica aqueous sol, a thermal treatment hollow silica aqueous sol, or a mixture thereof. This forms an aluminosilicate site on the outer shell of the hollow silica particles, and since the aluminosilicate site sometimes retains an alkali metal, the hollow silica sol of the raw material can be selected when the aluminum atoms measured by the leaching method are bonded to the surface of the hollow silica particles at 100 to 20,000 ppm/SiO ₂ based on the mass of SiO ₂ of the hollow silica particles in terms of Al ₂ O ₃ .

(ii) In the process, an aluminum compound is added to the hollow silica aqueous sol. The aluminum compound can be added to the hollow silica aqueous sol in the form of a solid or an aqueous solution.

(ii) The aluminum compound used in the process is at least one aluminum compound selected from the group consisting of aluminates, aluminum alkoxides, and hydrolyzates thereof, and can be used as an aqueous solution containing them. Examples of the aluminates include sodium aluminate, potassium aluminate, calcium aluminate, magnesium aluminate, ammonium aluminate, and aluminate amine salts. Examples of the aluminum alkoxides include aluminum isopropoxide, aluminum butoxide, and the like. In particular, aluminates can be preferably used.

These aluminum compounds are added in the form of an aqueous solution to the hollow silica aqueous sol obtained in process (I), and the concentration of the aqueous solution of the aluminum compounds is used in the range of 0.01 to 20 mass%, or 0.1 to 10 mass%, or 0.5 to 5 mass%. The addition can be performed under stirring of the hollow silica aqueous sol obtained in process (I). The addition time can be completed before heating, or the addition can be performed throughout the heating time.

The desired amount of aluminum compound impregnated into the hollow silica particles depends on the processing temperature in the (ii) process, and heat treatment is required within the above temperature range.

(i) The process may further include a process of adding an amine. The amine may be the amine described above, and may be contained in the hollow silica sol within the above range.

The above (ii) process may include a step of adding the aluminum compound, or at least one additive consisting of the aluminum compound and an amine and a neutral salt, and performing a heat treatment, and then contacting the aluminum compound with a cation exchange resin, a step of adding an acid, or a combination thereof. The cation exchange resin is a strongly acidic cation exchange resin of the H type, and may also be contacted with an anion exchange resin thereafter. The acid may be an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, or phosphoric acid, or an organic acid such as citric acid, acetic acid, malic acid, lactic acid, succinic acid, tartaric acid, butyric acid, fumaric acid, propionic acid, or formic acid.

In the present invention, the step (ii) may be performed by adding the aluminum compound (e.g., sodium aluminate), performing a heat treatment at 100 to 240°C for 0.1 to 48 hours, then adding an acid (e.g., sulfuric acid, nitric acid, hydrochloric acid), and bringing the resultant into contact with a cation exchange resin. The addition of the acid is a leaching operation that dissolves aluminum-containing components that were not doped into the particles by the heat treatment, or metal impurities contained in the particles, into the liquid, and is an operation to remove these metal-containing components with the cation exchange resin. Furthermore, a step of heating and maturing at 40 to 100°C for 0.1 to 48 hours, and then bringing the resultant into contact with the cation exchange resin again may be performed.

(iii) As a process, a process of additionally solvent-substituting the aqueous medium of the aqueous sol of hollow silica with an alcohol, ketone, ether, or ester having 1 to 10 carbon atoms;

Additionally, the process (iv) may include adding at least one silane compound selected from the group consisting of formulae (1) and (2) and heating.

The above processes (iii) and (iv) may be performed by, after completion of the above process (ii), performing solvent replacement with an alcohol having 1 to 10 carbon atoms in the process (iii), adding at least one silane compound selected from the group consisting of formulae (1) and (2) in the process (iv), heating, and then further performing solvent replacement with a ketone, ether, amide, urea, or ester having 1 to 10 carbon atoms.

By using the above method for producing a hollow silica sol, the surface charge of the hollow silica particles contained in the sol can be adjusted.

Example

Hereinafter, examples and comparative examples are shown and the present invention is described in more detail, but the present invention is not limited to the following examples.

The hollow silica sol used in the examples and comparative examples is as follows.

[Hollow silica sol]

Water-dispersed hollow silica sol (manufactured by Ningbo Dilato, trade name: HKT-A20-40D, hollow silica aqueous sol, heated at a temperature of 100°C to 240°C in an aqueous medium, pH 9.3, particle size by dynamic light scattering method: 55 nm, average primary particle size by TEM observation: 43 nm, TEM-converted specific surface area (D) of 63 m ² /g, specific surface area ratio (C/D ratio) of 2.4, silica concentration of 20 mass%, content of Na: 14 ppm/SiO ₂ , i.e., the content of Na ₂ O is 6.64×10 ^-6 mol/SiO ₂ as a molar ratio of Na ₂ O to SiO ₂ )

[basic compound]

Sodium hydroxide solution (Kwandong Chemical Co., Ltd., Product name: 4 mol/L sodium hydroxide solution)

Diethanolamine (Tokyo Chemical Industry Co., Ltd., Trade Name: Diethanolamine)

According to the following method, the properties of the water-dispersed hollow silica sol, the dispersions of silica particles prepared in the examples and comparative examples, and the hollow silica sol and dispersions during the process of manufacturing the dispersions were measured and evaluated.

[Measurement of silica (SiO ₂ ) concentration]

The silica concentration of the hollow silica sol dispersed in water, the hollow silica sol dispersed in methanol, and the hollow silica sol during the manufacturing process of the methanol-dispersed hollow silica sol, and the dispersion of surface-modified silica particles were calculated by placing the hollow silica sol or dispersion in a crucible, removing the solvent by heating, calcining at 1000°C, and weighing the calcination residue.

[pH measurement]

The measurement was made at 25℃ using a pH meter (manufactured by Dong-A DKK Co., Ltd., product name: MM-43X).

For organic solvents that can be mixed freely with water, such as methanol sol and propylene glycol monomethyl ether sol, measurements were made using a solution in which pure water and the sol were mixed in a mass ratio of 1:1, and for organic solvent sols with low solubility in water, such as methyl ethyl ketone sol, measurements were made using a solution in which pure water, methanol, and the organic solvent sol were mixed in a mass ratio of 1:1:1.

[Moisture measurement]

The moisture content of the organic solvent dispersion sol was measured using the Karl Fischer titration method.

[Method for analyzing sodium content]

0.2 g of the powder obtained by drying the hollow silica sol was treated with 20 mL of a 48 mass% hydrofluoric acid solution to remove the silica component, and the residue was dissolved in 20 mL of a 0.1 mol/liter (N/10) nitric acid aqueous solution. The content of Na in the obtained aqueous solution was measured using an ICP-OES analyzer (trade name CIROS120 E0P (Rigaku Corporation)), and the content of Na in the entire silica particles was obtained by dividing it by the content of Si.

[Measurement of particle size using dynamic light scattering (DLS)]

The particle size of the dynamic light scattering method was measured using a dynamic light scattering method particle size measuring device (Spectris, product name: Zetasizer Nano). The Z-average particle size was adopted as the dynamic light scattering method particle size.

[Measurement of specific surface area (C)(S _N2 ) by nitrogen adsorption method (BET method)]

The nitrogen adsorption specific surface area (S _N2 ) of silica particles in a water-dispersed hollow silica sol was measured by removing water-soluble cations in the water-dispersed hollow silica sol with a cation exchange resin (Dow Chemical Co., product name: Amberlite IR-120B), drying the hollow silica sol at 290°C to prepare a measurement sample, and using a nitrogen adsorption specific surface area measuring device, Monosorb (Quantachrome Instruments Japan, Ltd.).

[Measurement of average primary particle diameter by TEM (transmission electron microscope)]

Silica particles in the hollow silica sol were photographed with a transmission electron microscope (product name: JEM-F200, manufactured by Nippon Electronics Co., Ltd.), and about 300 randomly selected particles were binarized using an automatic image processing and analysis device (product name: LUZEX' AP, manufactured by Nireco Co., Ltd.), and the diameter of the projected area converted to a circle was measured as the average primary particle diameter (HEYWOOD diameter).

[TEM conversion surface area (D)]

Assuming a true particle with a true density of 2.2 g/cm ³ , the average primary particle diameter obtained from [Measurement of average primary particle diameter by TEM (transmission electron microscope)] was used to calculate (TEM-converted specific surface area (D) = 2720/average primary particle diameter).

[Measurement/leaching method of aluminum amount (A) bound to the surface of hollow silica particles]

The cation component in the hollow silica sol was removed with an H-type cation exchange resin, and the dried product from which the solvent was removed by heat treatment was pulverized in a mortar, and further treated at 250°C for 2 hours. 0.2 g of the obtained powder was placed in a polypropylene container (PP sampler bottle, 50 mL) containing 20 mL of a 0.1 mol/liter (N/10) nitric acid aqueous solution, and the powder was shaken vigorously by hand to mix. Next, ultrasonic treatment was performed for 10 minutes using an ultrasonic cleaner (ASU CLEANER ASU-10M manufactured by Azone) to sufficiently affinate the powder and the nitric acid aqueous solution. The resultant was placed in a 50°C constant temperature bath and maintained for 17 hours. Thereafter, the contents were cooled to room temperature, placed in a centrifugal ultrafiltration filter (Amicon Ultra-15, molecular weight cutoff 10,000), and the aluminum content in the filtrate obtained by centrifugation was measured using an ICP emission spectrometer, and the amount of aluminum bound to the surface of the hollow silica particles was converted to Al ₂ O ₃ , and the ratio of the mass of SiO ₂ of the hollow silica (Al ₂ O ₃ (ppm)/SiO ₂ ) was obtained.

[Measurement/dissolution method of aluminum (B) present in the entire hollow silica particle]

0.2 g of the powder obtained by drying the purified hollow silica sol was treated with 20 mL of a 48 mass% hydrofluoric acid solution to remove the silica component, and the residue was dissolved in 20 mL of a 0.1 mol/liter (N/10) nitric acid aqueous solution. The amount of aluminum in the obtained aqueous solution was measured by an ICP emission spectrometer, and the amount of aluminum present in the entire hollow silica particles was converted to Al ₂ O ₃ to obtain the ratio of the mass of SiO ₂ of the hollow silica (Al ₂ O ₃ (ppm)/SiO ₂ ).

[Measurement of surface charge of hollow silica particles]

Hollow silica sol was added and diluted in 10 mL of methanol so that the silica concentration became 0.5 mass%, and used as a measurement sample. The titration value until the streaming potential of the measurement sample became zero was measured using a 0.001 mol/L (N/1000) diallyldimethylammonium chloride solution (manufactured by Boysterbo Co., Ltd., product name PCD-06) as a cation standard titrant by a particle charge meter (manufactured by Boysterbo Co., Ltd.). The obtained titration value was converted to the value per 1 g of hollow silica particles by dividing it by the silica mass contained in the measurement sample, and this value was used as the surface charge (μeq/g-SiO ₂ ).

〔Example 1〕

(a) Process: 150 g of water-dispersed hollow silica sol (manufactured by Ningbo Dilato, trade name: HKT-A20-40D) was placed in a 500-cc eggplant-shaped flask, and while stirring with a magnetic stirrer, a sodium hydroxide aqueous solution was added dropwise so that the sodium content of the water-dispersed hollow silica sol became 384 ppm/SiO ₂ (i.e., the content of Na _{2 O} was 182.16×10 ^-6 mol/SiO ₂ as the molar ratio of Na ₂ O to SiO 2 ). The obtained silica sol had a pH of 10.1, a particle size of 55 nm by dynamic light scattering, an average primary particle size of 43 nm by TEM observation, a silica concentration of 20 mass%, a specific surface area (C) of 150 m ² /g by the BET method, a specific surface area (D) of 63 m ² /g converted to TEM, a specific surface area ratio (C/D ratio) of 2.4, the amount of aluminum (A) bound to the particle surface was 0.1 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, the amount of aluminum (B) present in the entire particle was 0.5 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, and the (A/B ratio) was 0.20. The amount of sodium contained in the water-dispersed hollow silica sol was 384 ppm/SiO ₂ , i.e., the amount of contained Na ₂ O was 384 ppm/SiO ₂ with respect to SiO ₂ . The molar ratio of O was 182×10 ^-6 mol/SiO ₂ .

(b) Process: After that, 56 g of methanol was added to 150 g of the obtained water-dispersed hollow silica sol, and methanol was fed while distilling off water using a rotary evaporator while heating and reducing pressure (bath temperature: 120°C, reduced pressure: 580 Torr), thereby obtaining a methanol dispersion of hollow silica (methanol-dispersed hollow silica sol). When the moisture content of the methanol-dispersed hollow silica sol became 2.0 mass% or less, methanol substitution was terminated, thereby obtaining 150 g of methanol-dispersed hollow silica sol.

The obtained methanol-dispersed hollow silica sol has a silica concentration of 21 mass%, a moisture content of 1.3 mass%, a particle size of 66 nm by dynamic light scattering, a pH of 9.0, a specific surface area (C) of 150 m ² /g by the BET method, a specific surface area (D) of 63 m ² /g converted to TEM, a specific surface area ratio (C/D ratio) of 2.4, an amount of aluminum (A) bound to the particle surface is 0.1 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, an amount of aluminum (B) present in the entire particle is 0.5 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, and the (A/B ratio) is 0.20, and an amount of sodium contained in the methanol-dispersed hollow silica sol is 384 ppm/SiO ₂ , i.e., an amount of contained Na _{2 O is 1.0 times the amount of Na 2} O contained relative to SiO _{2 .} The molar ratio of ₂ O was 182×10 ^-6 mol/SiO ₂ .

The obtained methanol-dispersed hollow silica sol was sealed in a 30 cc glass bottle and further stored in an explosion-proof thermostatic chamber (product name: thermostatic chamber with safety door, manufactured by Espec Co., Ltd.) kept at 50°C for 48 hours, and the stability of the methanol-dispersed hollow silica sol was confirmed by comparing the dynamic light scattering particle sizes before and after storage at 50°C. When the dynamic light scattering particle size before 50°C was within a range of 2.0 times the dynamic light scattering particle size after 48 hours of storage at 50°C, it was evaluated as “stable”, and when it exceeded 2.0 times the value, it was evaluated as “unstable”. The stability of the methanol-dispersed hollow silica sol obtained in Example 1 is shown in Table 1.

〔Example 2〕

(a) Process: 150 g of water-dispersed hollow silica sol (manufactured by Ningbo Dilato, trade name: HKT-A20-40D) was placed in a 500-cc eggplant flask, and while stirring with a magnetic stirrer, a sodium hydroxide aqueous solution was added dropwise so that the sodium content of the water-dispersed hollow silica sol became 384 ppm/SiO ₂ (i.e., the content of Na _{2 O} was 182.16×10 ^-6 mol/SiO 2 as a molar ratio of Na ₂ O to SiO ₂ ). Furthermore, 0.16 g of diethanolamine was added dropwise while stirring with a magnetic stirrer. The obtained silica sol had a pH of 10.2, a particle size of 55 nm by dynamic light scattering, an average primary particle size of 43 nm by TEM observation, a silica concentration of 20 mass%, a specific surface area (C) of 150 m ² /g by the BET method, a specific surface area (D) of 63 m ² /g converted to TEM, a specific surface area ratio (C/D ratio) of 2.4, the amount of aluminum (A) bound to the particle surface was 0.1 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, the amount of aluminum (B) present in the entire particle was 0.5 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, (A/B ratio) was 0.20, and the amount of sodium contained in the water-dispersed hollow silica sol was 384 ppm/SiO ₂ , i.e., the amount of contained Na ₂ O was 384 ppm/SiO 2 with respect to SiO _{2 .} The molar ratio of O was 182×10 ^-6 mol/SiO ₂ .

(b) Process: After that, 56 g of methanol was added to 150 g of the obtained water-dispersed hollow silica sol, and methanol was fed while distilling off water using a rotary evaporator while heating and reducing pressure (bath temperature: 120°C, reduced pressure: 580 Torr), thereby obtaining a methanol dispersion of hollow silica (methanol-dispersed hollow silica sol). When the moisture content of the methanol-dispersed hollow silica sol became 2.0 mass% or less, methanol substitution was terminated, thereby obtaining 150 g of methanol-dispersed hollow silica sol.

The obtained methanol-dispersed hollow silica sol has a silica concentration of 21 mass%, a moisture content of 0.4 mass%, a particle size of 66 nm by dynamic light scattering, a specific surface area (C) of 150 m ² /g by the BET method, a specific surface area (D) of 63 m ² /g converted to TEM, a specific surface area ratio (C/D ratio) of 2.4, an amount of aluminum (A) bound to the particle surface is 0.1 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, an amount of aluminum (B) present in the entire particle is 0.5 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, and the (A/B ratio) is 0.20, and an amount of sodium contained in the methanol-dispersed hollow silica sol is 384 ppm/SiO ₂ , i.e., an amount of Na ₂ O contained is the ratio of Na ₂ O to SiO _2. The molar ratio was 182×10 ^-6 mol/SiO ₂ .

The same stability test as in Example 1 was performed and the results are shown in Table 1.

〔Example 3〕

(a) Process: 150 g of water-dispersed hollow silica sol (manufactured by Ningbo Dilato, trade name: HKT-A20-40D) was placed in a 500-cc eggplant flask, and while stirring with a magnetic stirrer, a sodium hydroxide aqueous solution was added dropwise so that the sodium content of the water-dispersed hollow silica sol became 384 ppm/SiO ₂ (i.e., the content of Na _{2 O} was 182.16×10 ^-6 mol/SiO 2 as a molar ratio of Na ₂ O to SiO ₂ ). Furthermore, 0.16 g of diethanolamine was added dropwise while stirring with a magnetic stirrer. The obtained silica sol had a pH of 10.2, a particle size of 55 nm by dynamic light scattering, an average primary particle size of 43 nm by TEM observation, a silica concentration of 20 mass%, a specific surface area (C) of 150 m ² /g by the BET method, a specific surface area (D) of 63 m ² /g converted to TEM, a specific surface area ratio (C/D ratio) of 2.4, the amount of aluminum (A) bound to the particle surface was 0.1 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, the amount of aluminum (B) present in the entire particle was 0.5 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, (A/B ratio) was 0.20, and the amount of sodium contained in the water-dispersed hollow silica sol was 384 ppm/SiO ₂ , i.e., the amount of contained Na ₂ O was 384 ppm/SiO 2 with respect to SiO _{2 .} The molar ratio of O was 182×10 ^-6 mol/SiO ₂ .

(b) Process: After that, 56 g of methanol was added to 150 g of the obtained water-dispersed hollow silica sol, and methanol was fed while distilling off water using a rotary evaporator while heating and reducing pressure (bath temperature: 120°C, reduced pressure: 580 Torr), thereby obtaining a methanol dispersion of hollow silica (methanol-dispersed hollow silica sol). When the moisture content of the methanol-dispersed hollow silica sol became 2.0 mass% or less, methanol substitution was terminated, thereby obtaining 150 g of methanol-dispersed hollow silica sol.

30 g of methanol-dispersed hollow silica sol was placed in a 50 cc eggplant-shaped flask, and 0.33 g of pure water was added while stirring with a magnetic stirrer. The obtained methanol-dispersed hollow silica sol has a silica concentration of 21 mass%, a moisture content of 1.5 mass%, a particle size of 66 nm by dynamic light scattering, a specific surface area (C) of 150 m ² /g by the BET method, a specific surface area (D) of 63 m ² /g converted to TEM, a specific surface area ratio (C/D ratio) of 2.4, an amount of aluminum (A) bound to the particle surface is 0.1 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, an amount of aluminum (B) present in the entire particle is 0.5 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, and the (A/B ratio) is 0.20, and an amount of sodium contained in the methanol-dispersed hollow silica sol is 384 ppm/SiO ₂ , i.e., an amount of Na ₂ O contained is the ratio of Na ₂ O to SiO _{2 .} The molar ratio was 182×10 ^-6 mol/SiO ₂ .

The same stability test as in Example 1 was performed and the results are shown in Table 1.

〔Example 4〕

(a) Process: 150 g of water-dispersed hollow silica sol (manufactured by Ningbo Dilato, trade name: HKT-A20-40D) was placed in a 500-cc eggplant-shaped flask, and while stirring with a magnetic stirrer, a sodium hydroxide aqueous solution was added dropwise so that the sodium content of the water-dispersed hollow silica sol became 192 ppm/SiO ₂ (i.e., the content of Na _{2 O} was 91.08×10 ^-6 mol/SiO 2 as a molar ratio of Na ₂ O to SiO ₂ ). Furthermore, 0.16 g of diethanolamine was added dropwise while stirring with a magnetic stirrer. The obtained silica sol had a pH of 9.8, a particle size of 55 nm by dynamic light scattering, an average primary particle size of 43 nm by TEM observation, a silica concentration of 20 mass%, a specific surface area (C) of 150 m ² /g by the BET method, a specific surface area (D) of 63 m ² /g converted to TEM, a specific surface area ratio (C/D ratio) of 2.4, the amount of aluminum (A) bound to the particle surface was 0.1 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, the amount of aluminum (B) present in the entire particle was 0.5 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, (A/B ratio) was 0.20, and the amount of sodium contained in the water-dispersed hollow silica sol was 192 ppm/SiO ₂ , i.e., the amount of Na ₂ O contained was the ratio of Na ₂ O to SiO _2. The molar ratio was 91×10 ^-6 mol/SiO ₂ .

(b) Process: After that, 56 g of methanol was added to 150 g of the obtained water-dispersed hollow silica sol, and methanol was fed while distilling off water using a rotary evaporator while heating and reducing pressure (bath temperature: 120°C, reduced pressure: 580 Torr), thereby obtaining a methanol dispersion of hollow silica (methanol-dispersed hollow silica sol). When the moisture content of the methanol-dispersed hollow silica sol became 2.0 mass% or less, methanol substitution was terminated, thereby obtaining 150 g of methanol-dispersed hollow silica sol.

The obtained methanol-dispersed hollow silica sol has a silica concentration of 21 mass%, a moisture content of 0.6 mass%, a particle size of 66 nm by dynamic light scattering, a specific surface area (C) of 150 m ² /g by the BET method, a specific surface area (D) of 63 m ² /g converted to TEM, a specific surface area ratio (C/D ratio) of 2.4, an amount of aluminum (A) bound to the particle surface is 0.1 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, an amount of aluminum (B) present in the entire particle is 0.5 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, and the (A/B ratio) is 0.20, and an amount of sodium contained in the methanol-dispersed hollow silica sol is 192 ppm/SiO ₂ , i.e., an amount of Na ₂ O contained is the ratio of Na ₂ O to SiO _2. The molar ratio was 182×10 ^-6 mol/SiO ₂ .

The same stability test as in Example 1 was performed and the results are shown in Table 1.

〔Example 5〕

(a) Process: 150 g of water-dispersed hollow silica sol (manufactured by Ningbo Dilato, trade name: HKT-A20-40D) was placed in a 500-cc eggplant-shaped flask, and while stirring with a magnetic stirrer, a sodium hydroxide aqueous solution was added dropwise so that the sodium content of the water-dispersed hollow silica sol became 192 ppm/SiO ₂ (i.e., the content of Na _{2 O} was 91.08×10 ^-6 mol/SiO 2 as a molar ratio of Na ₂ O to SiO ₂ ). Furthermore, 0.16 g of diethanolamine was added dropwise while stirring with a magnetic stirrer. The obtained silica sol had a pH of 9.8, a particle size of 55 nm by dynamic light scattering, an average primary particle size of 43 nm by TEM observation, a silica concentration of 20 mass%, a specific surface area (C) of 150 m ² /g by the BET method, a specific surface area (D) of 63 m ² /g converted to TEM, a specific surface area ratio (C/D ratio) of 2.4, the amount of aluminum (A) bound to the particle surface was 0.1 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, the amount of aluminum (B) present in the entire particle was 0.5 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, (A/B ratio) was 0.20, and the amount of sodium contained in the water-dispersed hollow silica sol was 192 ppm/SiO ₂ , i.e., the amount of Na ₂ O contained was the ratio of Na ₂ O to SiO _2. The molar ratio was 91×10 ^-6 mol/SiO ₂ .

(b) Process: After that, 56 g of methanol was added to 150 g of the obtained water-dispersed hollow silica sol, and methanol was fed while distilling off water using a rotary evaporator while heating and reducing pressure (bath temperature: 120°C, reduced pressure: 580 Torr), thereby obtaining a methanol dispersion of hollow silica (methanol-dispersed hollow silica sol). When the moisture content of the methanol-dispersed hollow silica sol became 2.0 mass% or less, methanol substitution was terminated, thereby obtaining 150 g of methanol-dispersed hollow silica sol.

30 g of the obtained methanol-dispersed hollow silica sol was placed in a 50 cc eggplant-shaped flask, and 0.27 g of pure water was added while stirring with a magnetic stirrer. The obtained methanol-dispersed hollow silica sol has a silica concentration of 21 mass%, a moisture content of 1.5 mass%, a particle size of 66 nm by dynamic light scattering, a specific surface area (C) of 150 m ² /g by the BET method, a specific surface area (D) of 63 m ² /g converted to TEM, a specific surface area ratio (C/D ratio) of 2.4, an amount of aluminum (A) bound to the particle surface is 0.1 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, an amount of aluminum (B) present in the entire particle is 0.5 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, and the (A/B ratio) is 0.20, and an amount of sodium contained in the methanol-dispersed hollow silica sol is 192 ppm/SiO ₂ , i.e., an amount of Na ₂ O contained is the ratio of Na ₂ O to SiO _2. The molar ratio was 182×10 ^-6 mol/SiO ₂ .

The same stability test as in Example 1 was performed and the results are shown in Table 1.

〔Example 6〕

(a) Process: 150 g of water-dispersed hollow silica sol (manufactured by Ningbo Dilato, trade name: HKT-A20-40D) was placed in a 500 cc eggplant flask, and 0.16 g of diethanolamine was added dropwise while stirring with a magnetic stirrer. The obtained silica sol had a pH of 9.5, a particle size of 55 nm by dynamic light scattering, an average primary particle size of 43 nm by TEM observation, a silica concentration of 20 mass%, a specific surface area (C) of 150 m ² /g by the BET method, a specific surface area (D) of 63 m ² /g converted to TEM, a specific surface area ratio (C/D ratio) of 2.4, the amount of aluminum (A) bound to the particle surface was 0.1 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, the amount of aluminum (B) present in the entire particle was 0.5 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, (A/B ratio) was 0.20, and the amount of sodium contained in the water-dispersed hollow silica sol was 14 ppm/SiO ₂ , i.e., the amount of Na ₂ O contained was the ratio of Na ₂ O to SiO _2. The molar ratio was 6.64×10 ^-6 mol/SiO ₂ .

(b) Process: After that, 56 g of methanol was added to 150 g of the obtained water-dispersed hollow silica sol, and methanol was fed while distilling off water using a rotary evaporator while heating and reducing pressure (bath temperature: 120°C, reduced pressure: 580 Torr), thereby obtaining a methanol dispersion of hollow silica (methanol-dispersed hollow silica sol). When the moisture content of the methanol-dispersed hollow silica sol became 2.0 mass% or less, methanol substitution was terminated, thereby obtaining 150 g of methanol-dispersed hollow silica sol.

(c) Process: Then, to 100 g of the obtained methanol-dispersed hollow silica sol, while stirring with a magnetic stirrer, a sodium hydroxide aqueous solution diluted with methanol was added dropwise so that the sodium content in _the water-dispersed hollow silica sol was 384 ppm/SiO ₂ , i.e., the content of Na ₂ O was 182.16×10 ^-6 mol/SiO 2 as the molar ratio of Na ₂ O to SiO ₂ .

The obtained methanol-dispersed hollow silica sol has a silica concentration of 20 mass%, a moisture content of 1.8 mass%, a particle size of 78 nm by dynamic light scattering, a specific surface area (C) of 150 m ² /g by the BET method, a specific surface area (D) of 63 m ² /g converted to TEM, a specific surface area ratio (C/D ratio) of 2.4, an amount of aluminum (A) bound to the particle surface is 0.1 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, an amount of aluminum (B) present in the entire particle is 0.5 ppm in terms of Al ₂ O ₃ with respect to the mass of SiO ₂ of the hollow silica particles, and the (A/B ratio) is 0.20, and an amount of sodium contained in the methanol-dispersed hollow silica sol is 384 ppm/SiO ₂ , i.e., an amount of Na ₂ O contained is the ratio of Na ₂ O to SiO _{2 .} The molar ratio was 182×10 ^-6 mol/SiO ₂ .

The same stability test as in Example 1 was performed and the results are shown in Table 1.

〔Comparative Example 1〕

(a) Process: 150 g of water-dispersed hollow silica sol (manufactured by Ningbo Dilato, trade name: HKT-A20-40D) was placed in a 500 cc eggplant flask, and 0.16 g of diethanolamine was added dropwise while stirring with a magnetic stirrer.

(b) Process: After that, 56 g of methanol was added to 150 g of the obtained water-dispersed hollow silica sol, and methanol was fed while distilling off water using a rotary evaporator while heating and reducing pressure (bath temperature: 120°C, reduced pressure: 580 Torr), thereby obtaining a methanol dispersion of hollow silica (methanol-dispersed hollow silica sol). When the moisture content of the methanol-dispersed hollow silica sol became 2.0 mass% or less, methanol substitution was terminated, thereby obtaining 150 g of methanol-dispersed hollow silica sol.

The obtained methanol-dispersed hollow silica sol had a silica concentration of 20 mass%, a moisture content of 0.8 mass%, and a particle size of 123 nm as measured by dynamic light scattering. The content of Na ₂ O was 6.64×10 ^-6 mol/SiO ₂ as a molar ratio of Na ₂ O to SiO ₂ .

The same stability test as in Example 1 was performed and the results are shown in Table 1.

〔Table 1〕

Table 1

Examples 1 to ₆ , which have an average particle size of 20 to 150 nm determined by a dynamic light scattering method and contain a monovalent alkali metal ion in a molar ratio of 7.12×10 ^-6 to 285×10 ^-6 (where M represents a monovalent alkali metal atom) relative to SiO ₂ of hollow silica particles, confirmed that the particle size values determined by the dynamic light scattering method after storage at 50°C for 48 hours were within a range of 2.0 times that before storage, and thus were highly stable.

Meanwhile, Comparative Example 1, a sol containing a monovalent alkali metal ion in a molar ratio of less than 7.12×10 -6 when converted to M ₂ O (where M represents a monovalent alkali metal atom) to SiO ₂ of hollow silica particles even though the average particle size determined by the dynamic light scattering method was 20 to ¹⁵⁰ nm, was confirmed to have low stability, as the value of the particle size determined by the dynamic light scattering method after storage at 50°C for 48 hours was more than 2.0 times that before storage.

In addition, as shown in Table 1, even if the average particle size by the dynamic light scattering method is 20 to 150 nm and the sol contains a monovalent alkali metal ion in a molar ratio of less than 7.12×10 ^-6 when converted to M ₂ O (wherein M represents a monovalent alkali metal atom) to SiO ₂ of the hollow silica particles, Example ₆ , which is obtained by adjusting by adding monovalent alkali metal ions after methanol substitution and contains a monovalent alkali metal ion in a molar ratio of 7.12×10 ^-6 to 285×10 ^-6 when converted to M ₂ O (wherein M represents a monovalent alkali metal atom) to SiO 2 of the hollow silica particles, had a particle size by the dynamic light scattering method after storage at 50°C of 48 hours within a range of 2.0 times that before storage, and was confirmed to be highly stable.

Industrial applicability

The present invention relates to an aqueous sol and an organic solvent sol comprising highly stable hollow silica particles, and further to a method for improving the stability of the sol having reduced storage stability and a method for producing the same.

Claims (23)

Containing hollow silica particles having a space inside the outer shell and a monovalent alkali metal ion,
A hollow silica sol containing the monovalent alkali metal ion in a molar number converted to _M2O (where M represents a monovalent alkali metal atom) in a ratio of 7.12×10 ^-6 to 285×10 ^-6 with respect to the molar number of _SiO2 of the hollow silica particles,
A hollow silica sol, the average particle diameter of which, as determined by dynamic light scattering after storage at 50°C for 48 hours, is within a range of 2.0 times the average particle diameter as determined by dynamic light scattering before storage. In the first paragraph,
A hollow silica sol wherein the above-mentioned primary alkali metal ion is sodium ion. In the first paragraph,
A hollow silica sol having an average particle diameter of 20 to 150 nm as determined by dynamic light scattering before storage. In the first paragraph,
A hollow silica sol further comprising an amine, wherein the amine is in an amount of 0.001 to 10 mass% with respect to SiO ₂ of the hollow silica particles. In paragraph 4,
A hollow silica sol, wherein the amine is at least one amine selected from the group consisting of primary amines, secondary amines, and tertiary amines having 1 to 10 carbon atoms. In paragraph 4,
The above amine is a hollow silica sol having a water-soluble amine having a water solubility of 80 g/L or more. In the first paragraph,
In addition, the hollow silica particles contain aluminum atoms that form aluminosilicate sites,
These aluminum atoms are bonded to the surface of hollow silica particles,
The mass of this aluminum atom is in the range of 100 to 20,000 ppm (A) in terms of Al ₂ O ₃ relative to the mass of SiO ₂ of the hollow silica particle.
The mass of this aluminum atom is a value measured by the Leaching method.
Hollow silica sol. In Article 7,
A hollow silica sol, wherein the leaching method for leaching aluminum atoms from a compound containing aluminum atoms bonded to the surface of hollow silica particles uses an aqueous solution of at least one inorganic acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid. In Article 7,
The mass of aluminum atoms present in the entire hollow silica particles is expressed as a ratio (B) of 120 to 50,000 ppm relative to the mass of SiO ₂ of the hollow silica particles in terms of Al ₂ O ₃ .
The mass of this aluminum atom is a value measured by dissolving hollow silica particles in a hydrofluoric acid solution.
A hollow silica sol having a ratio (A)/ratio (B) of 0.002 to 1.0. In the first paragraph,
A hollow silica sol comprising hollow silica particles having a ratio of [specific surface area (C) of silica particles by the BET method (nitrogen gas adsorption method)]/[specific surface area (D) of silica particles converted from a transmission electron microscope] of 1.40 to 5.00. In the first paragraph,
A hollow silica sol comprising hollow silica particles having a surface charge of 5 to 250 μeq/g per 1 g in terms of SiO ₂ . In the first paragraph,
The above hollow silica particles are additionally prepared according to the following formulas (1) and (2):

(In equation (1),
R ¹ is a group that binds to a silicon atom, and is independently
An organic group having an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxyl group, a protected carboxyl group, a carboxyl group-generating group, an imide group, or a cyano group, and also representing a group bonded to a silicon atom by a Si-C bond, or representing a combination of these groups,
R ² is a group or atom bonded to a silicon atom, which independently represents an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom having 1 or more carbon atoms, or a combination of these groups,
a represents an integer from 1 to 3,
In equation (2),
R ³ is a group bonded to a silicon atom, which independently represents an alkyl group, a halogenated alkyl group, an alkenyl group, 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 carboxyl group, a protected carboxyl group, a carboxyl group-generating group, an imide group, or a cyano group, and also represents a group bonded to a silicon atom via a Si-C bond, or represents a combination of these groups.
R ⁴ is a group or atom bonded to a silicon atom, which independently represents an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom having 1 or more carbon atoms, or a combination of these groups,
Y is a group or atom bonded to a silicon atom, representing an alkylene group, NH group, or oxygen atom,
b represents an integer from 1 to 3, and c represents an integer of 0 or 1.)
A hollow silica sol comprising hollow silica particles coated with at least one silane compound selected from the group consisting of compounds represented by the following formula: In the first paragraph,
The hollow silica sol above comprises a dispersion medium, wherein the dispersion medium is water, an alcohol having 1 to 10 carbon atoms, a ketone, an ether, an amide, urea, or an ester. A film-forming composition comprising hollow silica particles derived from the hollow silica sol described in any one of claims 1 to 13, and an organic resin or polysiloxane. A film having a visible light transmittance of 80% or more obtained from the film-forming composition described in Article 14. Process (I) to (II):
(I) Process: A process for preparing a hollow silica sol containing a dispersion medium;
(II) Process: (I) Process of adjusting the hollow silica sol by adding monovalent alkali metal ions to _the hollow silica particles in the process so that the molar ratio of monovalent alkali metal ions converted to _M2O (where M represents a monovalent alkali metal atom) to SiO2 of the hollow silica particles is 7.12×10 ^-6 to 285×10 ^-6 .
A method for producing a hollow silica sol according to any one of claims 1 to 13, comprising: In Article 16,
A method for producing a hollow silica sol in which the monovalent alkali metal ion in the above process (II) is a sodium ion. In Article 17,
A method for producing a hollow silica sol, wherein the adjustment of the sodium ion content in the above process (II) is performed by contacting the hollow silica sol obtained in the process (I) with a cation exchange resin or adding a sodium source. In Article 18,
A method for producing a hollow silica sol, wherein the addition of a sodium source in the above process (II) is addition of sodium hydroxide. In Article 16,
A method for producing a hollow silica sol, wherein the dispersion medium of the above processes (I) and (II) is water, an alcohol having 1 to 10 carbon atoms, a ketone, an ether, an amide, urea, or an ester. In Article 16,
A method for producing a hollow silica sol, comprising adding at least one process selected from the following (i) to (iv) to the above process (I), process (II), or both processes.
(i): Adding amine to hollow silica sol,
(ii): Adding sodium aluminate as an aluminum source and heating to form aluminosilicate sites in hollow silica particles;
(iii): Replacing the dispersion medium with another dispersion medium;
(iv): Further covering the hollow silica particles with at least one silane compound selected from the group consisting of formulae (1) and (2).


(In equation (1),
R ¹ is a group that binds to a silicon atom, and is independently
An organic group having an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an epoxy group, a (meth)acryloyl group, a mercapto group, an amino group, a ureido group, a polyether group, a carboxyl group, a protected carboxyl group, a carboxyl group-generating group, an imide group, or a cyano group, and also representing a group bonded to a silicon atom by a Si-C bond, or representing a combination of these groups,
R ² is a group or atom bonded to a silicon atom, which independently represents an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom having 1 or more carbon atoms, or a combination of these groups,
a represents an integer from 1 to 3,
In equation (2),
R ³ is a group bonded to a silicon atom, which independently represents an alkyl group, a halogenated alkyl group, an alkenyl group, 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 carboxyl group, a protected carboxyl group, a carboxyl group-generating group, an imide group, or a cyano group, and also represents a group bonded to a silicon atom via a Si-C bond, or represents a combination of these groups.
R ⁴ is a group or atom bonded to a silicon atom, which independently represents an alkoxy group, an acyloxy group, a hydroxy group, or a halogen atom having 1 or more carbon atoms, or a combination of these groups,
Y is a group or atom bonded to a silicon atom, representing an alkylene group, NH group, or oxygen atom,
b represents an integer from 1 to 3, and c represents an integer of 0 or 1.) A method for stabilizing a hollow silica sol comprising hollow silica particles having a space inside the outer shell,
In hollow silica sol, the average particle size value by dynamic light scattering method has increased compared to the time of manufacture.
The above monovalent alkali metal ion is added so that the mole number converted to _M2O (where M represents a monovalent alkali metal atom) is in a mole ratio of 7.12× ^10-6 to 285× ^10-6 with respect to the mole number of _SiO2 of the hollow silica particles in the hollow silica sol.
A method for stabilizing a hollow silica sol according to claim 1, characterized by reducing the average particle diameter by an enhanced dynamic light scattering method. In Article 22,
A method for stabilizing a hollow silica sol, wherein the above-mentioned primary alkali metal ion is sodium ion.