Hollow silica particles containing aluminum atoms and method for producing the same

Abstract

To provide a hollow silica sol for mixing hollow silica particles with good compatibility with organic solvents and resins, where aluminum atoms are bound to the surface of the hollow silica particles in a specific proportion in terms of Al2O3.SOLUTION: The invention provides hollow silica particles having a space inside an outer shell. The hollow silica particles contain aluminum atoms forming aluminosilicate sites. According to measurements by a leaching method, the aluminum atoms are bound to the surface of the hollow silica particles in a proportion (A) of 100 to 20000 ppm / SiO2 per gram of SiO2 in terms of Al2O3 of the hollow silica particles. The leaching method calculates the proportion (A) of compounds containing aluminum atoms bound to the surface of the hollow silica particles, where the particles have been leached using an aqueous solution of at least one mineral acid selected from the group consisting of sulfuric acid, nitric acid and hydrochloric acid, expressed as Al2O3 per gram of SiO2 of the hollow silica particles.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a sol in which hollow silica particles containing aluminum atoms are dispersed in water or an organic solvent, a method for producing the same, and a film-forming composition.

Background Art

[0002] Hollow silica particles having a silica outer shell and a space inside the outer shell have characteristics such as a low refractive index, low thermal conductivity (heat insulation), and electrical insulation due to their characteristics. Hollow silica particles are composed of a core corresponding to the hollow part and an outer shell forming the outside of the core. An aqueous dispersion of hollow silica particles is obtained by forming a silica layer outside the core in an aqueous medium and then removing the core. For example, a method for producing an acidic silica sol in which an alkaline aluminate aqueous solution containing aluminum atoms in a ratio of 0.0006 to 0.004 in terms of Al2O3 / SiO2 molar ratio is added to a dispersion of solid silica particles and heated at 80 to 250°C and then subjected to cation exchange is disclosed (see Patent Document 1). In addition, a method for obtaining an aqueous solid silica sol obtained by heating an active silica obtained by cation exchange of an alkaline silicate aqueous solution containing aluminum atoms at 80 to 300°C, or a method for obtaining an aqueous solid silica sol obtained by adding an alkaline aluminate salt to an aqueous silica sol and heating at 80 to 300°C. The solid silica particles obtained by these methods contain aluminum atoms that form aluminosilicate sites on their surfaces. A silica sol in which the silica particles are dispersed in a nitrogen-containing solvent and the aluminum atoms are bonded to the surface of the silica particles at a ratio of 800 to 20000 ppm / SiO2 in terms of Al2O3 is disclosed (see Patent Document 2). Further, a core-shell particle in which an aluminosilicate shell is formed by reacting a silane compound and an aluminum precursor with a template core composed of organic polymer micelles or reverse micelles in a range of Si / Al molar ratio of 7 to 15 is produced, and the shell (outer shell) is reacted with a basic aqueous solution or an acidic aqueous solution to form pores and remove the core, and a hydrothermal reaction is performed by heating at 160 to 200 °C to produce hollow silica sol (see Patent Document 3). [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 6-199515 [Patent Document 2] International Publication No. 2022 / 097694 [Patent Document 3] Korean Patent No. 10-1659709 [Summary of the Invention] [Problems to be Solved by the Invention]

[0004] It is known that aluminosilicate sites generated by the reaction between aluminate ions and silanol groups on the surface of silica particles give a negative charge to the silica particles in the silica sol. The aluminosilicate sites improve the stability of the silica particles in the dispersion medium by increasing the negative zeta potential. In particular, the compatibility between the silica particles and an organic solvent or a charged resin is improved. Further, by containing an aluminum compound in an acidic silicic acid solution and growing particles, the aluminum compound is encapsulated in the silica particles, and the alkali metal present in the silica particles is captured in the silica particles to obtain a stable silica sol. The alkali metal encapsulated in the silica particles is released outside the system over time and causes destabilization. And since aluminosilicate is generated inside the silica particles which are originally unnecessary for stabilization, the amount of aluminum present in the aluminosilicate of the silica particles increases, and the aluminum bound to the aluminosilicate The amount of alkali metal increases and eventually leaks out of the silica particles over time. In the case of solid silica particles without cavities in the silica particles, after forming the silica particles, it is possible to form aluminosilicate sites near the surface by impregnating the surface with an aluminum compound. Even if the aluminum compound penetrates to a portion close to the center of the silica particles, sodium remains retained inside. On the other hand, in hollow silica particles having a cavity inside the outer shell, the aluminum compound penetrates into the outer shell due to the impregnation of the aluminum compound from the outside. The aluminum compound impregnated on the outside of the outer shell and the aluminum compound impregnated to the inside of the outer shell each form aluminosilicate sites and there are also alkali metals bonded to them. The alkali metal present in the aluminosilicate site existing on the outside of the outer shell can be removed during production, but the alkali metal present in the aluminosilicate site existing on the inside of the outer shell is difficult to remove during production and may leak out through the pores of the outer shell over time.

Means for Solving the Problems

[0005] In view of the above circumstances, the inventors of the present invention conducted intensive studies and as a result, found that by measuring aluminum atoms present outside the outer shell of hollow silica particles and measurable by the leaching method, hollow silica particles with high dispersion stability in a medium and no concerns such as alkali metal leakage can be obtained.

[0006] In a first aspect, the present invention is hollow silica particles having a space inside the outer shell, the hollow silica particles containing aluminum atoms that form aluminosilicate sites, and in the measurement by the leaching method, the aluminum atoms are bonded to the surface of the hollow silica particles at a ratio (A) of 100 to 20,000 ppm / SiO2 in terms of Al2O3 per 1 g of SiO2. As a second aspect, the leaching method leaches hollow silica particles with an aqueous solution of at least one mineral acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid, and calculates the ratio (A) of the compound containing aluminum atoms bonded to the surface of the hollow silica particles to 1 g of SiO2 of the hollow silica particles in terms of Al2O3. The hollow silica particles according to the first aspect, As a third aspect, in the measurement by the dissolution method using a hydrofluoric acid aqueous solution, aluminum atoms present in the entire hollow silica particles are bonded at a ratio (B) of 120 to 50,000 ppm / SiO2 with respect to 1 g of SiO2 in terms of Al2O3, and the value obtained by dividing the ratio (A) by the ratio (B) is 0.001 to 1.0. The hollow silica particles according to the first aspect or the second aspect, As a fourth aspect, the ratio of [specific surface area (C) of hollow silica particles by the BET method (nitrogen gas adsorption method)] / [specific surface area (D) of hollow silica particles converted from a transmission electron microscope] is 1.40 to 5.00. The hollow silica particles according to any one of the first aspect to the third aspect, As a fifth aspect, the surface charge amount converted per 1 g of SiO2 of the hollow silica particles is 5 to 250 μeq / g. The hollow silica particles according to any one of the first aspect to the fourth aspect, As a sixth aspect, the hollow silica particles further have the formulas (1), (2), and (3):

Chemical formula

Chemical formula

[11] . A film having a visible light transmittance of 80% or more, obtained from the film-forming composition according to

[12] .

[15] The following (I) step and (II) step: (I) step: A step of preparing a hollow silica aqueous sol. (II) step: An aluminum compound is added to the hollow silica aqueous sol obtained in the (I) step at a rate of 0.0001 to 0.5 g in terms of Al2O3 per 1 g of the hollow silica particles, and heating is performed at 40 to 260 ° C for 0.1 to 48 hours. A method for producing the hollow silica sol according to [5], comprising the above steps.

[16] The method for producing hollow silica sol described in

[15] , wherein the aqueous hollow silica sol used in step (I) is obtained through a step of heating in an aqueous medium at a heating temperature of less than 100 °C,

[17] The method for producing hollow silica sol described in

[15] , wherein the aqueous hollow silica sol used in step (I) is obtained through a step of heating in an aqueous medium at a heating temperature of 100 °C to 240 °C,

[18] The method for producing hollow silica sol described in

[15] , wherein the aluminum compound used in step (II) is at least one aluminum compound selected from the group consisting of aluminates, aluminum alkoxides, and their hydrolyzates, and step (II) uses an aqueous solution containing them,

[19] The method for producing hollow silica sol described in

[15] , wherein step (II) includes step (II-i) of further adding an amine,

[20] The method for producing hollow silica sol described in

[15] , wherein step (II) includes step (II-ii) of adding a neutral salt composed of a combination of at least one cation selected from the group consisting of sodium ions, potassium ions, and ammonium ions and an inorganic anion or an organic anion to SiO2 of the hollow silica particles at a ratio of 0.1 to 10% by mass,

[21] The method for producing hollow silica sol described in

[20] , wherein the inorganic anion used in step (II-ii) is sulfate ion, chloride ion, or phosphate ion, and the organic anion is carboxylate ion, oxycarboxylate ion, or amino acid,

[22] The method for producing hollow silica sol described in

[15] , wherein the above step (II) includes a step of adding the above aluminum compound or at least one additive selected from the group consisting of the above aluminum compound, amine, and neutral salt to the aqueous hollow silica sol and heating, and then includes step (II-iii) of contacting with a cation exchange resin, step (II-iv) of adding an acid, or a combination thereof,

[23] After the completion of the above step (II), the aqueous medium in the hollow silica sol is further subjected to solvent substitution with an alcohol having 1 to 10 carbon atoms, a ketone having 1 to 10 carbon atoms, an ether having 1 to 10 carbon atoms, or an ester having 1 to 10 carbon atoms (step (III)). The method for producing a hollow silica sol according to

[15] ,

[24] After the completion of the above step (III), the method for producing a hollow silica sol according to

[23] , which further includes a step (IV) of adding at least one silane compound selected from the group consisting of formula (1), formula (2), and formula (3) defined in [4] and heating.

[25] In steps (III) and (IV) above, after the completion of step (II), the aqueous medium of the hollow silica sol is subjected to solvent substitution with an alcohol having 1 to 10 carbon atoms in step (III), and then at least one silane compound selected from the group consisting of formula (1), formula (2), and formula (3) is added and heated in step (IV). After that, the alcohol solvent is further subjected to solvent substitution with a ketone having 1 to 10 carbon atoms, an ether having 1 to 10 carbon atoms, or an ester having 1 to 10 carbon atoms. The method for producing a hollow silica sol according to

[24] .

[26] Relates to a method for adjusting the surface charge of hollow silica particles using the method for producing a hollow silica sol according to

[15] .

Advantages of the Invention

[0007] According to the present invention, aluminum atoms are bonded to the surface of the hollow silica particles at a specific ratio in terms of Al2O3 conversion, so that hollow silica particles with high dispersion stability in a medium and no concerns such as the outflow of alkali metals can be provided. Moreover, according to the present invention, by using the above hollow silica particles, a hollow silica sol having good compatibility with an organic solvent can be provided. Furthermore, according to the present invention, by using the above hollow silica particles or the above hollow silica sol, a film-forming composition having good compatibility with a resin can be provided. Also, according to the present invention, a method for producing a hollow silica sol having good compatibility with an organic solvent can be provided.

Embodiments for Carrying Out the Invention

[0008] The present invention relates to hollow silica particles having a space inside the outer shell, the hollow silica particles containing aluminum atoms that form 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 / SiO2 of the aluminum atoms per 1 g of SiO2 in terms of Al2O3 as measured by the leaching method.

[0009] The hollow silica particles have a silica outer shell and a space inside the outer shell. The hollow silica is obtained by a method in which an outer shell mainly composed of silica is formed on the surface of a portion corresponding to a core called a so-called template in a dispersion medium, and the portion corresponding to the core is removed.

[0010] In the present invention, aluminum present on the surface of silica particles can be measured by a leaching method using an aqueous solution of at least one mineral acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid, and the aluminum atoms can be expressed in terms of Al2O3. That is, in the measurement by the leaching method, the aluminum atoms are present on the surface of the hollow silica particles at a ratio (A) of 100 to 20,000 ppm / SiO2, or 100 to 15,000 ppm / SiO2, or 100 to 10,000 ppm / SiO2, or 100 to 3,000 ppm / SiO2, or 200 to 5,000 ppm / SiO2, or 500 to 5,000 ppm / SiO2, or 800 to 3,000 ppm / SiO2 in terms of Al2O3 per 1 g of SiO2. The presence of aluminum silicate sites on the surface of the silica particles is important for dispersion in solvents and resins. When producing an acidic hollow silica sol, it is desirable to increase the absolute value of the zeta potential of the hollow silica particles in the acidic region. However, when the content of aluminum atoms in terms of Al2O3 is less than 100 ppm / SiO2 at the ratio (A), the stability of the hollow silica particles tends to decrease. Further, when the content of aluminum atoms in terms of Al2O3 is 3,000 ppm / SiO2 or more at the ratio (A), the particle diameter after doping tends to increase with respect to the dynamic light scattering method particle diameter (DLS particle diameter) before the aluminum atoms are doped with an aluminum compound at the stage of the aluminum-containing hollow silica aqueous sol.

[0011] Aluminum atoms present as aluminosilicate on the surface of silica particles can be leached (eluted) into a structure similar to an aluminum salt, aluminum oxide, or aluminum hydroxide by an aqueous solution of at least one mineral 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 can be expressed in terms of Al2O3. In particular, a method of leaching (eluting) using an aqueous nitric acid solution is used. The aqueous nitric acid solution used for leaching can be used in the range where the pH of the aqueous solution is 0.5 to 4.0, 0.5 to 3.0, 0.5 to 2.0, or 1.0 to 1.5, and typically an aqueous nitric acid solution with a pH of 1.0 can be used. For example, 100 mL of the above aqueous nitric acid solution is added to 1 g of silica, and it is held at a temperature of 20 to 70 °C or 40 to 60 °C for 10 to 24 hours to elute the aluminum compound from the silica particle surface, and it can be used as a sample for analysis.

[0012] In the present invention, the silica particle surface can be defined as a region where an aluminum compound can be eluted by the above leaching. It is obtained by evaporating the solvent from a silica sol and further drying it at 250 °C to obtain silica gel, which is then ground into silica powder. 20 mL of an aqueous nitric acid solution with a pH of 1.0 is added to 0.2 g of the silica powder, shaken well, held in a thermostat at 50 °C for 17 hours, and then centrifuged and filtered. The aluminum content in the filtrate is measured using an ICP emission spectrometer, and the aluminum content in terms of Al2O3 is divided by the mass of the silica powder to determine the amount of aluminum (Al2O3 / SiO2) (ppm) bonded to the silica particle surface.

[0013] Also, even when forming an aluminosilicate on the surface of silica particles, depending on the manufacturing method, aluminosilicate may be formed not only selectively on the surface but also inside the silica particles. The aluminum atoms present in the entire hollow silica particles including the surface and the inside are bonded to the silica particles at a ratio (B) of 120 to 50,000 ppm / SiO2, or 500 to 20,000 ppm / SiO2, or 500 to 10,000 ppm / SiO2, or 1,000 to 5,000 ppm / SiO2, or 1,000 to 4,000 ppm / SiO2, or 120 to 4,000 ppm / SiO2 in terms of Al2O3 per 1 g of SiO2 of the hollow silica particles.

[0014] When producing an acidic hollow silica sol, it is desirable to increase the absolute value of the zeta potential of the hollow silica particles in the acidic region. However, when the content of aluminum atoms in terms of Al2O3 is less than 120 ppm / SiO2 in the ratio (B), the stability of the hollow silica particles tends to decrease. Also, when the content of aluminum atoms in terms of Al2O3 is 4,000 ppm / SiO2 or more in the ratio (B), the particle diameter after doping tends to increase with respect to the dynamic light scattering method particle diameter (DLS particle diameter) before doping of aluminum atoms with an aluminum compound at the stage of the aluminum-containing hollow silica aqueous sol. The ratio (A) / (B), which is the ratio of aluminum present on the surface of the silica particles to the entire 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.

[0015] The aluminum atoms present in the entire silica particles can be shown in terms of Al2O3 by measurement using a dissolution method with an aqueous hydrofluoric acid solution. That is, the aluminum atoms present as aluminosilicate in the entire silica particles can be measured from the solution using an ICP emission spectroscopic analyzer by dissolving the silica particles with an aqueous hydrofluoric acid solution, and the content of aluminum atoms present in the entire silica particles can be shown in terms of Al2O3.

[0016] ​

[0017] By forming aluminosilicate sites on the surface of the silica particles in this way, the negative charge amount per 1 g of SiO2 of the hollow silica particles present on the surface of the silica particles is measured in the range of 5 to 250 μeq / 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.

[0018] The above hollow silica particles can be obtained as a hollow silica sol dispersed in a dispersion medium. A sol in which hollow silica particles are dispersed in a dispersion medium and having an average particle diameter of the hollow silica particles in the range of 20 to 150 nm by the dynamic light scattering method can be obtained.

[0019] Hollow silica is obtained by forming a silica-based outer shell on the surface of a part corresponding to a core called a so-called template in a dispersion medium and removing the part corresponding to the core. In this state, it is a hollow silica aqueous sol.

[0020] The hollow silica aqueous sol thus obtained can be subjected to solvent substitution with an alcohol solvent as an organic solvent. As the above alcohol solvent, an alcohol having 1 to 5 carbon atoms which may have an ether bond is preferable, and examples thereof include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, propylene glycol monomethyl ether, and propylene glycol monoethyl ether. Thereafter, if desired, after coating with a silane compound, it can be further subjected to solvent substitution with another organic solvent.

[0021] In the present invention, examples of the organic solvent include alcohols having 1 to 10 carbon atoms, ketones having 1 to 10 carbon atoms, ethers having 1 to 10 carbon atoms, and esters having 1 to 10 carbon atoms. The alcohol having 1 to 10 carbon atoms is an aliphatic alcohol, and examples thereof include primary alcohols, secondary alcohols, and tertiary alcohols. And it is also possible to use polyhydric alcohols for these alcohols, and examples thereof include dihydric alcohols and trihydric alcohols. Examples of monohydric primary alcohols include methanol, ethanol, 1-propanol, 1-butanol, 1-hexanol, and the like. Examples of monohydric secondary alcohols include 2-propanol, 2-butanol, cyclohexanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and the like. Examples of monohydric tertiary alcohols include tert-butyl alcohol and the like. Examples of dihydric alcohols include methanediol, ethylene glycol, propylene glycol and the like. Examples of trihydric alcohols include glycerin and the like.

[0022] As the ketone having 1 to 10 carbon atoms, aliphatic ketones can be preferably used. For example, acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, methyl cyclopentanone, and the like can be mentioned.

[0023] As the ether having 1 to 10 carbon atoms, aliphatic ethers can be preferably used. For example, dimethyl ether, ethyl methyl ether, diethyl ether, tetrahydrofuran, 1,4-dioxane, and the like can be mentioned.

[0024] As the ester having 1 to 10 carbon atoms, aliphatic esters can be preferably used. For example, 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, dipropyl adipate, and the like can be mentioned.

[0025] In the above-mentioned hollow silica aqueous sol and hollow silica organic solvent sol as raw materials, the average particle diameter of the hollow silica particles 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 as measured by the dynamic light scattering method (DLS method).

[0026] Also, the average primary particle diameter of the hollow silica particles by transmission electron microscope observation 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.

[0027] Also, the specific surface area (C) of the hollow silica particles by the BET method (nitrogen gas adsorption method) is 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 and can be set.

[0028] Also, the specific surface area (D) of the hollow silica particles converted from the transmission electron microscope is 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 can be set. And the ratio of [specific surface area (C) of hollow silica particles by BET method (nitrogen gas adsorption method)] / [specific surface area (D) of hollow silica particles 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 is solid silica particles with no space inside the outer shell of the silica particles. When the value of (C) / (D) exceeds 1.0, it indicates that the silica particles are hollow silica particles with space inside the outer shell.

[0029] Also, the thickness of the outer shell of the hollow silica particles by transmission electron microscope observation 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.

[0030] And the refractive index of the above 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.

[0031] Also, the hollow silica sol can be obtained by using a concentration of SiO2 particles of 1 to 50% by mass, or 5 to 40% by mass, typically 10 to 30% by mass.

[0032] The pH of the above sol can be adjusted from acidic to alkaline. Adjustment to acidic is carried out by adding an inorganic acid or an organic acid. Also, adjustment to alkaline is carried out by adding an inorganic base or an organic base. As the organic base, an amine can be added for the purpose of adjusting the pH and the surface charge amount. The pH can be set to less than pH 1 to 7 on the acidic side and pH 7 or more and 13 or less on the alkaline side.

[0033] Before adding the amine, the aqueous sol of hollow silica can be set in the range of, for example, pH 2.0 to 6.0, or pH 2.0 to 4.5, and by adding the amine, it can be adjusted to the range of, for example, pH 3.0 to 10.0, or 3.0 to 9.0.

[0034] In the case of an organic solvent sol, the above pH is the pH when pure water with the same mass as the organic solvent sol is mixed at a ratio of 1:1. When the organic solvent is a water-miscible organic solvent, it can be measured. However, when later solvent substitution is carried out with a hydrophobic organic solvent, it is preferable to measure the pH at the stage of a methanol solvent sol in advance.

[0035] For example, for a dispersion medium such as a methanol sol and a propylene glycol monomethyl ether sol which are hydrophilic organic solvents, it is measured in a solution obtained by mixing pure water and the sol at a mass ratio of 1:1. For a dispersion medium such as a methyl ethyl ketone sol which is a hydrophobic organic solvent, it can be measured in a solution obtained by mixing pure water, methanol, and methyl ethyl ketone sol at a mass ratio of 1:1:1.

[0036] The hollow silica organic solvent sol is subjected to solvent substitution from an aqueous medium to an alcohol solvent having 1 to 5 carbon atoms, and further to an organic solvent. In this process, moisture may remain. At the stage of the alcohol sol of hollow silica, for example, the residual moisture can be contained in the sol in an amount of 0.1 to 3.0% by mass, or 0.1 to 1.0% by mass. And at the stage of the organic solvent sol of hollow silica (the dispersion medium is an organic solvent other than alcohol), it can be contained in an amount of 0.01 to 0.5% by mass.

[0037] Also, in the hollow silica organic solvent sol, the viscosity can be set in the range of 1.0 to 10.0 mPa·s.

[0038] An amine can be added to the hollow silica sol of the present invention. As the amine used in the present invention, a water-soluble amine having a water solubility of 80 g / L or more, or 100 g / L or more can be used.

[0039] In the hollow silica aqueous sol as a raw material and the hollow silica organic solvent sol obtained by solvent substitution, it can contain an amine, or an amine and ammonia. The amine can be added and contained in the range of 0.001 to 10% by mass, or 0.01 to 10% by mass, or 0.1 to 10% by mass based on SiO2 of the hollow silica particles. And the amine, or the amine and ammonia can be shown as the total nitrogen amount in the hollow silica particle organic solvent sol by these base components, and can be contained, for example, in the range of 10 to 100000 ppm, or 100 to 10000 ppm, or 100 to 3000 ppm, or 100 to 2000 ppm, typically 200 to 2000 ppm.

[0040] Examples of the amine include aliphatic amines and aromatic amines, and aliphatic amines can be preferably used. At least one amine selected from the group consisting of primary, secondary, and tertiary amines having 1 to 10 carbon atoms can be used. Those amines are water-soluble and are at least one amine selected from the group consisting of primary, secondary, and tertiary amines having 1 to 10 carbon atoms.

[0041] Examples of the primary amine include monomethylamine, monoethylamine, monopropylamine, monoisopropylamine, monobutylamine, monoisobutylamine, monosec-butylamine, monotert-butylamine, monomethanolamine, monoethanolamine, monopropanolamine, monoisopropanolamine, monobutanolamine, monoisobutanolamine, monosec-butanolamine, monotert-butanolamine, etc.

[0042] Examples of the secondary amine include dimethylamine, diethylamine, dipropylamine, diisopropylamine, N-methylethylamine, N-ethylisobutylamine, dimethanolamine, diethanolamine, dipropanolamine, diisopropanolamine, N-methanolethylamine, N-methylethanolamine, N-ethanolisobutylamine, N-ethylisobutanolamine, and the like.

[0043] Examples of the tertiary amine include trimethylamine, triethylamine, tripropylamine, triisopropylamine, tributylamine, triisobutylamine, tri-sec-butylamine, tri-tert-butylamine, trimethanolamine, triethanolamine, tripropanolamine, triisopropanolamine, tributanolamine, triisobutanolamine, tri-sec-butanolamine, tri-tert-butanolamine, and the like.

[0044] The water solubility of the above amines is preferably 80 g / L or more, or 100 g / L or more. As the above amines, primary amines and secondary amines are preferred, and secondary amines are more preferred because of their low volatility and high solubility. Examples include diisopropylamine, diethanolamine, and the like.

[0045] In the present invention, by containing the above amines, the surface charge amount per 1 g of SiO2 of the hollow silica particles can be set to 5 μeq / g or more, or 25 μeq / g or more. Typically, it can be set in the 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.

[0046] In the present invention, by adjusting the type and addition amount of the above amines, the surface charge amount of the hollow silica particles can be adjusted to an arbitrary surface charge amount.

[0047] In the present invention, the surface of the hollow silica particles can be coated with a silane compound. As the above silane compound, it can be coated with a hydrolyzate of at least one silane compound selected from the group consisting of the above formulas (1) to (3).

[0048] In the above formula (1), R 1 each represents an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, or an organic group having 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 an Si-C bond, and R 2 each represents an alkoxy group, an acyloxy group, or a halogen group, a represents an integer of 1 to 3, In formulas (2) and (3), R 3 and R 5 each represents 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 by an Si-C bond, R 4 and R 6 each represents an alkoxy group, an acyloxy group, or a halogen group, Y represents an alkylene group, an NH group, or an oxygen atom, b is an integer of 1 to 3, c is an integer of 0 or 1, and d is an integer of 1 to 3.

[0049] The above alkyl group is an alkyl group having 1 to 18 carbon atoms, such as methyl group, ethyl group, n-propyl group, i-propyl group, cyclopropyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, cyclobutyl group, 1-methyl-cyclopropyl group, 2-methyl-cyclopropyl group, n-pentyl group, 1-methyl-n-butyl group, 2-methyl-n-butyl group, 3-methyl-n-butyl group, 1,1-dimethyl-n-propyl group, 1,2-dimethyl-n-propyl group, 2,2-dimethyl-n-propyl group, 1-ethyl-n-propyl group, cyclopentyl group, 1-methyl-cyclobutyl group, 2-methyl-cyclobutyl group, 3-methyl-cyclobutyl group, 1,2-dimethyl-cyclopropyl group, 2,3-dimethyl-cyclopropyl group, 1-ethyl-cyclopropyl group, 2-ethyl-cyclopropyl group, n-hexyl group, 1-methyl-n-pentyl group, 2-methyl-n-pentyl group, 3-methyl-n-pentyl group, 4-methyl-n-pentyl group, 1,1-dimethyl-n-butyl group, 1,2-dimethyl-n-butyl group, 1,3-dimethyl-n-butyl group, 2,2-dimethyl-n-butyl group, 2,3-dimethyl-n-butyl group, 3,3-dimethyl-n-butyl group, 1-ethyl-n-butyl group, 2-ethyl-n-butyl group, 1,1,2-trimethyl-n-propyl group, 1,2,2-trimethyl-n-propyl group, 1-ethyl-1-methyl-n-propyl group, 1-ethyl-2-methyl-n-propyl group, cyclohexyl group, 1-methyl-cyclopentyl group, 2-methyl-cyclopentyl group, 3-methyl-cyclopentyl group, 1-ethyl-cyclobutyl group, 2-ethyl-cyclobutyl group, 3-ethyl-cyclobutyl group, 1,2-dimethyl-cyclobutyl group, 1,3-dimethyl-cyclobutyl group, 2,2-dimethyl-cyclobutyl group, 2,3-dimethyl-cyclobutyl group, 2,4-dimethyl-cyclobutyl group, 3,3-dimethyl-cyclobutyl group, 1-n-propyl-cyclopropyl group, 2-n-propyl-cyclopropyl group, 1-i-propyl-cyclopropyl group, 2-i-propyl-cyclopropyl group, 1,2,2-trimethyl-cyclopropyl group, 1,2,3-trimethyl-cyclopropyl group, 2,2,Examples include, but are not limited to, 3-trimethyl-cyclopropyl group, 1-ethyl-2-methyl-cyclopropyl group, 2-ethyl-1-methyl-cyclopropyl group, 2-ethyl-2-methyl-cyclopropyl group, 2-ethyl-3-methyl-cyclopropyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, etc.

[0050] In addition, examples of the alkylene group include alkylene groups derived from the above-mentioned alkyl groups.

[0051] The above aryl group is an aryl group having 6 to 30 carbon atoms, and examples thereof include phenyl group, naphthyl group, anthracene group, pyrene group, etc.

[0052] The alkenyl group is an alkenyl group having 2 to 10 carbon atoms, and examples thereof include ethenyl group, 1-propenyl group, 2-propenyl group, 1-methyl-1-ethenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-ethylethenyl group, 1-methyl-1-propenyl group, 1-methyl-2-propenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 1-n-propylethenyl group, 1-methyl-1-butenyl group, 1-methyl-2-butenyl group, 1-methyl-3-butenyl group, 2-ethyl-2-propenyl group, 2-methyl-1-butenyl group, 2-methyl-2-butenyl group, 2-methyl-3-butenyl group, 3-methyl-1-butenyl group, 3-methyl-2-butenyl group, 3-methyl-3-butenyl group, 1,1-dimethyl-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- Examples include, but are not limited to, methyl-2-pentenyl group, 1-methyl-3-pentenyl group, 1-methyl-4-pentenyl group, 1-n-butylethenyl group, 2-methyl-1-pentenyl group, 2-methyl-2-pentenyl group, etc.

[0053] Examples of the above alkoxy group include, but are not limited to, alkoxy groups having 1 to 10 carbon atoms, such as methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group, s-butoxy group, t-butoxy group, n-pentyloxy group, 1-methyl-n-butoxy group, 2-methyl-n-butoxy group, 3-methyl-n-butoxy group, 1,1-dimethyl-n-propoxy group, 1,2-dimethyl-n-propoxy group, 2,2-dimethyl-n-propoxy group, 1-ethyl-n-propoxy group, n-hexyloxy group, etc.

[0054] Examples of the above acyloxy group include, but are not limited to, acyloxy groups having 2 to 10 carbon atoms, such as methylcarbonyloxy group, ethylcarbonyloxy group, n-propylcarbonyloxy group, i-propylcarbonyloxy group, n-butylcarbonyloxy group, i-butylcarbonyloxy group, s-butylcarbonyloxy group, t-butylcarbonyloxy group, n-pentylcarbonyloxy group, 1-methyl-n-butylcarbonyloxy group, 2-methyl-n-butylcarbonyloxy group, 3-methyl-n-butylcarbonyloxy group, 1,1-dimethyl-n-propylcarbonyloxy group, 1,2-dimethyl-n-propylcarbonyloxy group, 2,2-dimethyl-n-propylcarbonyloxy group, 1-ethyl-n-propylcarbonyloxy group, n-hexylcarbonyloxy group, 1-methyl-n-pentylcarbonyloxy group, 2-methyl-n-pentylcarbonyloxy group, etc.

[0055] Examples of the above halogen atom include fluorine, chlorine, bromine, iodine, etc.

[0056] Examples of the organic group having a polyether group include a polyetherpropyl group having an alkoxy group. For example, (CH3O)3SiC3H6(OC2H4)nOCH3 can be mentioned. n can be used in the range of 1 to 100, or 1 to 10.

[0057] Examples of the organic group having an epoxy group include a 2-(3,4-epoxycyclohexyl)ethyl group, a 3-glycidoxypropyl group, and the like.

[0058] The above (meth)acryloyl group represents both an acryloyl group and a methacryloyl group. Examples of the organic group having a (meth)acryloyl group include a 3-methacryloxypropyl group, a 3-acryloxypropyl group, and the like.

[0059] Examples of the organic group having a mercapto group include a 3-mercaptopropyl group.

[0060] 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.

[0061] Examples of the organic group having a ureido group include a 3-ureidopropyl group.

[0062] Examples of the organic group having a cyano group include a 3-cyanopropyl group. The above formulas (2) and (3) are preferably compounds capable of forming a trimethylsilyl group on the surface of silica particles. These compounds can be exemplified as follows.

Chemical formula

[0063] On the surface of the silica particles, a hydroxyl group, for example, if it is silica particles, a silanol group, can react with the above silane compound to coat the surface of the silica particles with the above silane compound through a siloxane bond. The reaction temperature can be in the range from 20°C to the boiling point of the dispersion medium, for example, it can be carried out in the range of 20°C to 100°C. The reaction time can be about 0.1 to 6 hours.

[0064] As the coating amount of the above silane compound on the silica particle surface, a silane compound corresponding to a coating amount of 0.1 atom of silicon atoms in the silane compound per nm 2 to 6.0 atoms per nm 2 can be added to the silica sol to coat the surface of the silica particles.

[0065] Water is required for the hydrolysis of the above silane compound, but if it is a sol of an aqueous solvent, those aqueous solvents are used. The moisture remaining in the solvent when the aqueous medium is solvent-exchanged with an organic solvent can be used. For example, moisture present in an amount of 0.01 to 1% by mass can be used. Also, the hydrolysis can be carried out either with a catalyst or without a catalyst.

[0066] When it is carried out without a catalyst, it is the case where the surface of the silica particles is present on the acidic side (pH less than 7). When a catalyst is used, examples of the hydrolysis catalyst include metal chelate compounds, organic acids, inorganic acids, organic bases, and inorganic bases. Examples of the metal chelate compound as the hydrolysis catalyst include triethoxy·mono(acetylacetonato)titanium, triethoxy·mono(acetylacetonato)zirconium, and the like. Examples of the organic acid as the hydrolysis catalyst include acetic acid, oxalic acid, and the like. Examples of the inorganic acid as the hydrolysis catalyst include hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, phosphoric acid, and the like. Examples of the organic base as the hydrolysis catalyst include pyridine, pyrrole, piperazine, and quaternary ammonium salts. Examples of the inorganic base as the hydrolysis catalyst include ammonia, sodium hydroxide, and potassium hydroxide.

[0067] 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 threonine. Examples of the chelating agents include ethylenediaminetetraacetic acid, L-aspartic acid-N,N-diacetic acid, and diethylenetriaminepentaacetic acid. Examples of the organic acid salts include alkali metal salts, ammonium salts, and amine salts of the above organic acids. Examples of the alkali metals include sodium and potassium.

[0068] In the present invention, a film-forming composition containing the above hollow silica organic solvent sol and an organic resin is obtained.

[0069] An organic resin is selected and mixed from thermosetting or photocurable resins to obtain a film-forming composition. And it can be made into a cured product by including 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, photo radical generator), or an acid generator-based curing agent (thermal acid generator, or photo acid generator).

[0070] This composition can form a cured product by applying or filling a film-forming composition containing an organic resin and a curing agent onto a substrate and then heating, irradiating with light, or a combination thereof. Examples of the organic resin (curable resin) include resins having functional groups such as epoxy groups or (meth)acryloyl groups, and isocyanate-based resins. For example, a photocurable polyfunctional acrylate can be preferably used.

[0071] Examples of the polyfunctional acrylate include polyfunctional acrylates having 2-functional, 3-functional, 4-functional, or more functional groups in the molecule, such as neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and the like. As these polyfunctional acrylates, for example, compounds represented by the following formulas can also be mentioned.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0072] The film-forming composition of the present invention can contain a surfactant (leveling agent). As the surfactant (leveling agent), an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, and a silicone-based surfactant 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, based on the organic resin.

[0073] Examples of the anionic surfactant used in the present invention include sodium salts and potassium salts of fatty acids, alkylbenzene sulfonates, higher alcohol sulfates, polyoxyethylene alkyl ether sulfates, α-sulfo fatty acid esters, α-olefin sulfonates, monoalkyl phosphate salts, and alkane sulfonates.

[0074] For example, alkylbenzene sulfonates include sodium salts, potassium salts, and lithium salts, such as sodium C10-C16 alkylbenzene sulfonate, C10-C16 alkylbenzene sulfonic acid, and sodium alkylnaphthalene sulfonate.

[0075] Examples of higher alcohol sulfates include sodium dodecyl sulfate (sodium lauryl sulfate) having 12 carbon atoms, triethanolamine lauryl sulfate, and triethanolammonium lauryl sulfate.

[0076] Examples of 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. Examples of α-olefin sulfonates include sodium α-olefin sulfonate.

[0077] Examples of alkane sulfonates include sodium 2-ethylhexyl sulfate.

[0078] Examples of the cationic surfactant used in the present invention include alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, and amine salt-based agents.

[0079] Alkyltrimethylammonium salts are quaternary ammonium salts and have chloride ions or bromide ions as counterions. For example, dodecyltrimethylammonium chloride, cetyltrimethylammonium chloride, coconut alkyltrimethylammonium chloride, alkyl (C16-18) trimethylammonium chloride, etc. can be mentioned.

[0080] Dialkyldimethylammonium salts have two main chains with lipophilicity and two methyl groups. Bis(hydrogenated tallow) dimethylammonium chloride can be mentioned. For example, didecyldimethylammonium chloride, didiacylalkyldimethylammonium chloride, dihardened tallow alkyldimethylammonium chloride, dialkyl (C14-18) dimethylammonium chloride, etc. can be mentioned.

[0081] Alkyldimethylbenzylammonium salts are quaternary ammonium salts having one main chain with lipophilicity, two methyl groups, and a benzyl group, and benzalkonium chloride can be mentioned. For example, alkyl (C8-18) dimethylbenzylammonium chloride can be mentioned.

[0082] As amine salt-based agents, those in which one or more hydrogen atoms of ammonia are substituted with hydrocarbon groups, for example, N-methylbis(hydroxyethyl)amine fatty acid ester hydrochloride can be mentioned.

[0083] The amphoteric surfactants used in the present invention include alkylaminofatty acid salts of the N-alkyl-β-alanine type, alkylbetaines of the alkylcarboxybetaine type, and alkylamine oxides of the N,N-dimethyldodecylamine oxide type. Examples thereof include lauryl betaine, stearyl betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, and lauryldimethylamine oxide.

[0084] 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, as the polyoxyethylene alkyl ether, there are 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, polyoxyethylene isodecyl ether, and the like.

[0085] Examples of the polyoxyethylene alkylphenol ether include polyoxyethylene styrenated phenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene distyrenated phenyl ether, and polyoxyethylene tribenzylphenyl ether.

[0086] Examples of the alkyl glucoside include decyl glucoside and lauryl glucoside.

[0087] Examples of the polyoxyethylene fatty acid ester include polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, polyethylene glycol distearate, polyethylene glycol dioleate, and polypropylene glycol dioleate.

[0088] 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 monoesquioleate, and ethylene oxide adducts thereof.

[0089] Examples of polyoxyethylene sorbitan fatty acid esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan triisostearate, etc.

[0090] Examples of fatty acid alkanolamides include coconut oil fatty acid diethanolamide, tallow fatty acid diethanolamide, lauric acid diethanolamide, oleic acid diethanolamide, etc.

[0091] Furthermore, polyoxyalkyl ethers or polyoxyalkyl glycols such as polyoxyethylene polyoxypropylene glycol, polyoxyethylene fatty acid esters, polyoxyethylene hydrogenated castor oil ether, sorbitan fatty acid ester alkyl ether, alkyl polyglucosides, sorbitan monooleate, sucrose fatty acid esters, etc. can be mentioned.

[0092] A silicone-based surfactant can be used. The silicone-based surfactant is a compound having a repeating unit containing a siloxane bond in the main chain. The weight average molecular weight of the silicone-based surfactant can be used in the range of 500 to 50,000. These may be modified silicone-based surfactants, and examples include structures in which an organic group is introduced into the side chain and / or the terminal of the polysiloxane. Examples of the organic group 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. Examples of the silicone-based surfactant include trade names, Toray Silicone DC3PA, Toray Silicone SH7PA, Toray Silicone DC11PA, Toray Silicone SH21PA, Toray Silicone SH28PA, Toray Silicone SH29PA, Toray Silicone SH30PA, Toray Silicone SH8400 (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 (manufactured by Momentive Performance Materials), KP-341, KF-6001, KF-6002 (manufactured by Shin-Etsu Silicone Co., Ltd.), BYK307, BYK323, BYK330 (manufactured by BYK Chemie), etc. For example, a polyether-modified silicone with the trade name L-7001 (manufactured by DOWSIL) can be preferably used.

[0093] In the present invention, a film-forming composition containing the above organic solvent sol and an organic resin is obtained. The film-forming composition can be obtained by removing the organic solvent in the organic solvent sol to obtain a film-forming composition containing hollow silica particles and an organic resin.

[0094] In the case of a thermosetting film-forming composition among the above-described film-forming compositions, a thermosetting agent can be added in an amount of 0.01 to 50 phr, or in the range of 0.01 to 10 phr, with respect to a functional group-containing resin such as an epoxy group or a (meth)acryloyl group. For example, the thermosetting agent can be contained in a proportion of 0.5 to 1.5 equivalents, preferably 0.8 to 1.2 equivalents, with respect to a functional group such as an epoxy group or a (meth)acryloyl group. The equivalent amount of the thermosetting agent with respect to the curable resin is indicated by the equivalent ratio of the thermosetting agent with respect to the functional group.

[0095] Examples of the thermosetting agent include phenolic resins, amine-based curing agents, polyamide resins, imidazoles, polymercaptans, acid anhydrides, thermal radical generators, thermal acid generators, etc. Particularly, thermal radical generator-based curing agents, acid anhydride-based curing agents, and amine-based curing agents are preferable. These thermosetting agents can be used by dissolving them in a solvent even if they are solids. However, since evaporation of the solvent causes a decrease in the density of the cured product, a decrease in strength due to the formation of pores, and a decrease in water resistance, it is preferable that the curing agent itself is liquid at normal temperature and normal pressure.

[0096] Examples of the phenolic resin include phenolic novolak resins, cresol novolak resins, etc.

[0097] Examples of the amine-based curing agent 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, m-xylenediamine, metaphenylenediamine, diaminodiphenyl Examples include lumetane, diaminodiphenyl sulfone, 3,3'-diethyl-4,4'-diaminodiphenylmethane, diethyltoluenediamine, etc. Among these, liquid diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, di(1-methyl-2-aminocyclohexyl)methane, menthendiamine, isophoronediamine, diaminodicyclohexylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, diethyltoluenediamine, etc. can be preferably used.

[0098] The polyamide resin is formed by the condensation of dimer acid and polyamine, and is a polyamideamine having a primary amine and a secondary amine in the molecule.

[0099] Examples of imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, epoxyimidazole adduct, etc.

[0100] The polymercaptan is, for example, one having a mercaptan group at the end of a polypropylene glycol chain or one having a mercaptan group at the end of a polyethylene glycol chain, and a liquid one is preferred.

[0101] As the acid anhydride-based curing agent, an anhydride of a compound having a plurality of carboxyl groups in one molecule is preferred. Examples of these acid anhydride-based curing agents include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bistrimellitate, glycerol tristrimellitate, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, methylcyclohexene dicarboxylic anhydride, chlorendic anhydride, etc.

[0102] Examples of the thermal acid generator include sulfonium salts and phosphonium salts, and sulfonium salts are preferably used. For example, the following compounds can be exemplified. [Chemical formula] R includes an alkyl group having 1 to 12 carbon atoms and an aryl group having 6 to 20 carbon atoms, and an alkyl group having 1 to 12 carbon atoms is particularly preferred.

[0103] Among these, methyltetrahydrophthalic anhydride, methyl-5-norbornene-2,3-dicarboxylic anhydride (methyl nadic anhydride, methyl hymic anhydride), hydrogenated methyl nadic anhydride, methylbutenyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, methylhexahydrophthalic anhydride, and a mixture of methylhexahydrophthalic anhydride and hexahydrophthalic anhydride, which are liquid at normal temperature and pressure, are preferred. These liquid acid anhydrides have a viscosity of about 10 mPa·s to 1000 mPa·s as measured at 25°C.

[0104] Examples of the thermal radical generator include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvalero nitrile), 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, benzoyl peroxide, etc. These can be obtained from Tokyo Chemical Industry Co., Ltd.

[0105] Also, when obtaining the above-mentioned cured product, a curing aid may be appropriately used in combination. Examples of the curing aid include organic phosphorus compounds such as triphenylphosphine and tributylphosphine, quaternary phosphonium salts such as ethyltriphenylphosphonium bromide and diethyl methyltriphenylphosphonium phosphate, 1,8-diazabicyclo(5,4,0)undec-7-ene, salts of 1,8-diazabicyclo(5,4,0)undec-7-ene and octylic acid, zinc octylate, and quaternary ammonium salts such as tetrabutylammonium bromide. These curing aids can be contained in a proportion of 0.001 to 0.1 part by mass with respect to 1 part by mass of the curing agent.

[0106] The composition is obtained in the form of a thermosetting varnish by mixing a resin, a curing agent, and, if desired, a curing aid. These mixtures can be carried out using a stirring blade or a kneader in a reaction vessel.

[0107] The mixing is carried out by a heat mixing method and is carried out at a temperature of 60°C to 100°C for 0.5 to 1 hour.

[0108] The obtained curable film-forming composition is a thermosetting coating composition and has an appropriate viscosity for use as, for example, a liquid encapsulant. The liquid thermosetting film-forming composition can be adjusted to an arbitrary viscosity and can be partially encapsulated at any location thereof in order to be used as a transparent encapsulant for LEDs or the like by a casting method, a potting method, a dispenser method, a printing method, or the like. After the liquid thermosetting composition is directly mounted on an LED or the like in a liquid state by the above-mentioned method and then dried and cured, an epoxy resin cured body is obtained.

[0109] The thermosetting film-forming composition (thermosetting coating composition) is applied to a substrate and heated at a temperature of 80°C to 200°C to obtain a cured product.

[0110] When the above-described film-forming composition is a photocurable resin composition, a photoinitiator (photo radical generator, photoacid generator) can be added to a resin containing a functional group such as an epoxy group or a (meth)acryloyl group in an amount of 0.01 to 50 phr, or in the range of 0.01 to 10 phr. For example, the photoinitiator (photo radical generator, photoacid generator) can be contained in an amount of 0.5 to 1.5 equivalents, preferably 0.8 to 1.2 equivalents, relative to a functional group such as an epoxy group or a (meth)acryloyl group. The equivalent amount of the photoinitiator with respect to the curable resin is represented by the equivalent ratio of the photoinitiator with respect to the functional group.

[0111] The photo radical generator is not particularly limited as long as it can generate radicals directly or indirectly by light irradiation.

[0112] Among photo radical generators, examples of photo radical polymerization initiators include imidazole compounds, diazo compounds, bisimidazole compounds, N-aryl glycine compounds, organic azide compounds, titanocene compounds, aluminate compounds, organic peroxides, N-alkoxypyridinium salt compounds, and thioxanthone compounds. Examples of azide compounds include p-azidobenzaldehyde, p-azidoacetophenone, p-azidobenzoic acid, p-azidobenzalacetophenone, 4,4'-diazidochalcone, 4,4'-diazidodiphenyl sulfide, and 2,6-bis(4'-azidobenzal)-4-methylcyclohexanone. can be mentioned. Examples of the diazo compound include 1-diazo-2,5-diethoxy-4-p-tolylmercaptobenzene borofluoride, 1-diazo-4-N,N-dimethylaminobenzene chloride, and 1-diazo-4-N,N-diethylaminobenzene borofluoride. Examples of the bisimidazole compound 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. Examples of the titanocene compound 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), bis(methylcyclopentadienyl)-titanium-bis(2,6-difluorophenyl), and dicyclopentadienyl-titanium-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl).

[0113] Examples of the photo radical generator also 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-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone.

[0114] Examples of these photo radical polymerization initiators include, for example, Irgacure TPO (the component is 2,4,6-trimethylbenzoyldiphenylphosphine oxide) (c1-1-1) manufactured by BASF, Omnirad819 (the component is bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide) (c1-1-2) manufactured by IGM RESINS, and Irgacure 184 (the component is 1-hydroxycyclohexyl phenyl ketone) (c1-1-3) manufactured by IGM RESINS, which can be obtained.

Chemical formula

[0115] The photoacid generator is not particularly limited as long as it can generate an acid directly or indirectly by light irradiation.

[0116] Specific examples of the photoacid generator include triazine compounds, acetophenone derivative compounds, disulfone compounds, diazomethane compounds, sulfonic acid derivative compounds, onium salts such as iodonium salts, sulfonium salts, phosphonium salts, selenium salts, metallocene complexes, iron arene complexes, and the like.

[0117] The onium salts used as the above photoacid generators include, as iodonium salts, 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, bis(p-chlorophenyl)iodonium chloride, bis(p-chlorophenyl)iodonium tetrafluoroborate, and further bis(alkylphenyl)iodonium salts such as bis(4-t-butylphenyl)iodonium hexafluorophosphate, alkoxycarbonylalkoxy-trialkylaryliodonium salts (for example, 4-[(1-ethoxycarbonyl-ethoxy)phenyl]-(2,4,6-trimethylphenyl)-iodonium hexafluorophosphate, etc.), bis(alkoxyaryl)iodonium salts (for example, bis(alkoxyphenyl)iodonium salts such as (4-methoxyphenyl)phenyliodonium hexafluoroantimonate, etc.).

[0118] Triphenylsulfonium salts such as triphenylsulfonium chloride, triphenylsulfonium bromide, tri(p-methoxyphenyl)sulfonium tetrafluoroborate, tri(p-methoxyphenyl)sulfonium hexafluorophosphate, tri(p-ethoxyphenyl)sulfonium tetrafluoroborate, triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, etc., and sulfonium salts such as (4-phenylthiophenyl)diphenylsulfonium hexafluoroantimonate, (4-phenylthiophenyl)diphenylsulfonium hexafluorophosphate, bis[4-(diphenylsulfonio)phenyl]sulfide-bis-hexafluoroantimonate, bis[4-(diphenylsulfonio)phenyl]sulfide-bis-hexafluorophosphate, (4-methoxyphenyl)diphenylsulfonium hexafluoroantimonate) can be mentioned.

[0119] Phosphonium salts such as triphenylphosphonium chloride, triphenylphosphonium bromide, tri(p-methoxyphenyl)phosphonium tetrafluoroborate, tri(p-methoxyphenyl)phosphonium hexafluorophosphate, tri(p-ethoxyphenyl)phosphonium tetrafluoroborate, 4-chlorobenzenediazonium hexafluorophosphate, benzyltriphenylphosphonium hexafluoroantimonate, etc., can be mentioned.

[0120] Selenium salts such as triphenylselenium hexafluorophosphate, and metallocene complexes such as (η5 or η6-isopropylbenzene)(η5-cyclopentadienyl)iron(II) hexafluorophosphate can be mentioned.

[0121] Also, the following compounds can also be used as photoacid generators.

Chemical formula

[0122] As sulfonium salt compounds and iodonium salt compounds are preferred as photoacid generators. As their anion species, CF3SO3 - , C4F9SO3 - , C8F 17 SO3 - , camphorsulfonic acid anion, tosylate anion, BF4 - , PF6 - , AsF6 - and SbF6 - etc. can be mentioned. Anion species such as phosphorus hexafluoride and antimony hexafluoride showing particularly strong acidity are preferred.

[0123] The film-forming composition of the present invention may contain conventional additives as necessary. Examples of such additives include pigments, colorants, thickeners, sensitizers, defoamers, coating property improvers, lubricants, stabilizers (such as antioxidants, heat stabilizers, and light stabilizers), plasticizers, dissolution accelerators, fillers, antistatic agents, etc. These additives may be used alone or in combination of two or more.

[0124] As a method for applying the film-forming composition of the present invention, for example, a flow coating method, a spin coating method, a spray coating method, a screen printing method, a casting method, a bar coating method, a curtain coating method, a roll coating method, a gravure coating method, a dipping method, a slit method, etc. can be mentioned.

[0125] In the present invention, a photocurable coating composition (film-forming composition) can be applied onto a substrate and cured by light irradiation. Further, heating can also be performed before and after light irradiation.

[0126] The thickness of the coating film can be selected from the range of about 0.01 μm to 10 mm according to the use of the cured product. For example, when used for a photoresist, it can be about 0.05 to 10 μm (particularly 0.1 to 5 μm), when used for a printed wiring board, it can be about 5 μm to 5 mm (particularly 100 μm to 1 mm), and when used for an optical thin film, it can be about 0.1 to 100 μm (particularly 0.3 to 50 μm).

[0127] 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%.

[0128] The light for irradiation or exposure when using a photoacid generator may be, for example, gamma rays, X-rays, ultraviolet rays, visible light, etc., and usually, visible light or ultraviolet rays, particularly ultraviolet rays, are often used. The wavelength of the light is, for example, about 150 to 800 nm, preferably 150 to 600 nm, more preferably about 150 to 400 nm. The irradiation light amount varies depending on the thickness of the coating film, but for example, it can be 2 to 20000 mJ / cm 2 , preferably 5 to 5000 mJ / cm 2 and so on. The light source can be selected according to the type of light rays for exposure. 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 beam (helium-cadmium laser, excimer laser, etc.) can be used. By such light irradiation, the curing reaction of the composition proceeds.

[0129] When using a thermal acid generator or when heating the coating film that is necessary after light irradiation using a photoacid generator, it is carried out, for example, at 60 to 350 °C, preferably about 100 to 300 °C. The heating time can be selected from the range of 3 seconds or more (for example, about 3 seconds to 5 hours), and can be carried out, for example, for 5 seconds to 2 hours, preferably about 20 seconds to 30 minutes, and usually can be carried out for about 1 minute to 3 hours (for example, 5 minutes to 2.5 hours).

[0130] Furthermore, when forming a pattern or an image (for example, when manufacturing a printed wiring board, etc.), the coating film formed on the substrate may be pattern-exposed. This pattern exposure may be carried out by scanning with a laser beam or may be carried out by irradiating light through a photomask. A pattern or an image can be formed by developing (or dissolving) the non-irradiated region (unexposed portion) generated by such pattern exposure with a developer.

[0131] As the developer, an alkaline aqueous solution or an organic solvent can be used.

[0132] Examples of the alkaline aqueous solution 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 amine aqueous solutions such as ethanolamine, propylamine, and ethylenediamine.

[0133] The alkaline developer is usually an aqueous solution of 10% by mass or less, and preferably an aqueous solution of 0.1 to 3.0% by mass is used. Furthermore, alcohols and surfactants can also be added to the above developer for use, and these are preferably 0.05 to 10 parts by mass with respect to 100 parts by mass of the developer. Among these, an aqueous solution of 0.1 to 2.38% by mass of tetramethylammonium hydroxide can be used. In addition, a general organic solvent can be used as the developing solution. For example, 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. can be mentioned, and these can be used as a mixture of one or more of them. In particular, propylene glycol methyl ether, propylene glycol methyl ether acetate, ethyl lactate, etc. can be preferably used.

[0134] In the present invention, an adhesion promoter can be added for the purpose of improving the adhesion to the substrate after development. Examples of the adhesion promoter include chloro- such as trimethylchlorosilane, dimethylvinylchlorosilane, methyldiphenylchlorosilane, chloromethyldimethylchlorosilane, etc. Alkoxysilanes such as rocylans, trimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane, dimethylvinyl ethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, etc., silazanes such as hexamethyldisilazane, N,N'-bis(trimethylsilyl)urea, dimethyltrimethylsilylamine, trimethylsilylimidazole, etc., silanes such as vinyltrichlorosilane, 3-chloropropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-(N-piperidinyl)propyltrimethoxysilane, etc., heterocyclic compounds such as benzotriazole, benzimidazole, indazole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, urazole, thiouracil, mercaptoimidazole, mercaptopyrimidine, etc., ureas such as 1,1-dimethylurea, 1,3-dimethylurea, or thiourea compounds can be mentioned. One of the above adhesion promoters can be used alone or in combination of two or more. The addition amount of these adhesion promoters is usually 18% by mass or less, preferably 0.0008 to 9% by mass, more preferably 0.04 to 9% by mass in the solid content.

[0135] The present invention may contain a sensitizer. Examples of the sensitizer that can be used include anthracene, phenothiazine, perylene, thioxanthone, benzophenone thioxanthone, and the like. Further, examples of the sensitizing dye include thiopyrylium salt dyes, merocyanine dyes, quinoline dyes, styrylquinoline dyes, ketocoumarin dyes, thioxanthene dyes, xanthene dyes, oxonol dyes, cyanine dyes, rhodamine dyes, pyrylium salt dyes, and the like. Particularly preferred is an anthracene-based sensitizer. When used in combination with a cationic curing catalyst (photo-sensitive cationic polymerization initiator), the sensitivity is dramatically improved, and it also has a radical polymerization initiation function. In the hybrid type in which the cationic curing system and the radical curing system of the present invention are used in combination, the catalyst species can be simplified. As specific anthracene compounds, dibutoxyanthracene, dipropoxyanthraquinone, and the like are effective. The addition amount of the sensitizer is used in a proportion of 0.01 to 20% by mass, preferably 0.01 to 10% by mass in the solid content.

[0136] The composition of the present invention can be photocured or thermally cured using a photo radical generator, a thermal radical generator, a photoacid generator, or a thermal acid generator. When using a photoacid generator or a thermal acid generator, for example, a commonly used epoxy curing agent (such as an amine or an acid anhydride) is not used or, even if used, their content is extremely low. Therefore, the storage stability of the composition of the present invention is improved.

[0137] The above composition has been found to be applicable to cationic photopolymerization. It has a higher curing rate than conventional liquid epoxy compounds (for example, alicyclic epoxy compounds having an epoxycyclohexyl ring). Since the curing rate is fast, it is possible to reduce the addition amount of the acid generator and use a weak acid-based acid generator. The reduction of the acid generator is important for preventing metal corrosion because acid active species may remain after UV irradiation. Since the curing rate is fast, thick film curing is possible.

[0138] Curing by UV irradiation can be applied to materials (equipment) that are vulnerable to heat.

[0139] The thermosetting materials and photocuring materials using the film-forming composition of the present invention have characteristics such as rapid hardening property, transparency, and small curing shrinkage, and can be used for coating and adhesion of electronic components, optical components (antireflection films), and precision mechanical components. For example, optical elements such as lenses of mobile phones and cameras, light-emitting diodes (LEDs), semiconductor lasers (LDs), components such as liquid crystal panels, biochips, lenses and prisms of cameras, magnetic components of hard disks such as personal computers, pickups of CD and DVD players (parts that capture optical information reflected from disks), cones and coils of speakers, magnets of motors, circuit boards, electronic components, and components inside engines of automobiles etc. It can be used for adhesion such as those mentioned above.

[0140] For hard coat materials for surface protection of automobile bodies, lamps, electrical appliances, building materials, plastics, etc., for example, it can be applied to automobile and motorcycle bodies, lenses and mirrors of headlights, plastic lenses of glasses, mobile phones, game machines, optical films, ID cards, etc.

[0141] For ink materials for printing on metals such as aluminum and plastics, etc., applications include printing inks for cards such as credit cards and membership cards, switches of electrical appliances and OA equipment, keyboards, and inks for inkjet printers for CDs, DVDs, etc.

[0142] Applications include techniques for curing resins in combination with 3D CAD to create complex three-dimensional objects, applications to stereolithography such as model making of industrial products, coating, adhesion, optical waveguides, thick film resists, etc. for optical fibers.

[0143] In addition, the film-forming composition of the present invention can be suitably used as an insulating resin for electronic materials such as antireflection films, semiconductor encapsulation materials, adhesives for electronic materials, printed wiring board materials, interlayer insulating film materials, encapsulation materials for power modules, etc., and insulating resins used in high-voltage equipment such as generator coils, transformer coils, and gas-insulated switchgear.

[0144] The hollow silica sol of the present invention can be produced by including the following steps (I) and (II). (I) Step: A step of preparing a hollow silica aqueous sol (II) Step: To the hollow silica aqueous sol obtained in step (I), an aluminum compound is added at a ratio of 0.0001 to 0.5 g in terms of Al2O3 per 1 g of the hollow silica particles, and heating is performed at 40 to 260 °C for 0.1 to 24 hours. The aluminum compound in step (II) can be added in the range of 0.0001 to 0.5 g, or 0.001 to 0.1 g, or 0.001 to 0.05 g in terms of Al2O3 per 1 g of the hollow silica particles. The heating temperature in step (II) is 40 to 260 °C, or 50 to 260 °C, or 60 to 240 °C. In the case of non-hydrothermal treatment, it is used at 40 to less than 100 °C, or 50 to less than 100 °C, or 60 to less than 100 °C, and in the case of hydrothermal treatment, it can be performed at 100 to 260 °C, or 150 to 240 °C. The heating time in step (II) 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.

[0145] (I) The hollow silica particles used in step (I) have a silica outer shell and a space inside the outer shell. The hollow silica is obtained by a method of forming an outer shell mainly composed of silica on the surface of a part corresponding to a core called a so-called template in an aqueous dispersion medium and removing the part corresponding to the core. The above template includes a method using an organic substance (for example, hydrophilic organic resin particles such as polyethylene glycol, polystyrene, polyester, etc.) and a method using an inorganic substance (for example, hydrophilic inorganic compound particles such as calcium carbonate, sodium aluminate, etc.).

[0146] (I) As the raw material hollow silica aqueous sol used in step (I), a non-hydrothermally treated hollow silica aqueous sol that has passed through a heating temperature of less than 100 °C, for example, less than 20 to 100 °C, or less than 40 to 100 °C, or less than 50 to 100 °C in an aqueous medium can be used. Further, as the hollow silica aqueous sol used in the (I) step, a hydrothermally treated hollow silica aqueous sol that has undergone a heating temperature of 100°C to 240°C, or 110 to 240°C in an aqueous medium can be used.

[0147] As the raw material hollow silica sol used in the present invention, a non-hydrothermally treated hollow silica aqueous sol, a hydrothermally treated hollow silica aqueous sol, or a mixture thereof can be used. This forms aluminosilicate sites on the outer shell of the hollow silica particles. However, since the aluminosilicate sites may hold alkali metals, in the measurement by the leaching method, when aluminum atoms are bonded to the surface of the hollow silica particles at a ratio of 100 to 20,000 ppm / SiO2 in terms of Al2O3 per 1 g of SiO2, the raw material hollow silica sol can be selected.

[0148] In the (II) step, an aluminum compound is added to the hollow silica aqueous sol obtained in the above (I) step. The aluminum compound can be added to the hollow silica aqueous sol obtained in the (I) step in a solid form or in the form of an aqueous solution.

[0149] When impregnating the hollow silica particles with an aluminum compound from the outside after the formation of the hollow silica particles, there are cases where the hollow silica particles are pre-hydrothermally treated to improve the density of the outer shell and then impregnated with the aluminum compound by heat treatment, and cases where the hollow silica particles that have not been pre-hydrothermally treated are impregnated with the aluminum compound by heat treatment. In both the former and the latter cases, it is preferable that aluminum atoms measurable by the leaching method are present in a specific ratio to silica.

[0150] (II) The aluminum compound used in the process is at least one aluminum compound selected from the group consisting of aluminates, aluminum alkoxides, and their hydrolyzates, and can be used as an aqueous solution containing them. Examples of aluminates include sodium aluminate, potassium aluminate, calcium aluminate, magnesium aluminate, ammonium aluminate, amine salts of aluminate, etc. Examples of aluminum alkoxides include aluminum isopropoxide, aluminum butoxide, etc. Particularly, aluminates can be preferably used.

[0151] These aluminum compounds are added to the hollow silica aqueous sol obtained in step (I) in the form of an aqueous solution. The concentration of the aqueous solution of the aluminum compound is used in the range of 0.01 to 20% by mass, or 0.1 to 10% by mass, or 0.5 to 5% by mass. The addition can be carried out under stirring of the hollow silica aqueous sol obtained in step (I). The addition can be completed before heating, or can also be carried out throughout the heating time.

[0152] The impregnation of the aluminum compound into the hollow silica particles depends to some extent on the treatment temperature in step (II), and it is necessary to carry out heat treatment in the above temperature range.

[0153] (II) The process can include a step (II-i) of further adding an amine. The amine can be the above-mentioned amine and can be contained in the hollow silica sol in the above range.

[0154] (II) The process can include a step (II-ii) of containing a neutral salt composed of a combination of at least one cation selected from sodium ions, potassium ions, and ammonium ions and an inorganic anion or an organic anion in a proportion of 0.1 to 10% by mass based on SiO2 of the hollow silica particles.

[0155] (II-ii) The inorganic anions used in the process are sulfate ions, chloride ions, or phosphate ions, and examples of the organic anions include carboxylate ions, oxycarboxylate ions, or amino acids. Examples of preferred neutral salts include sodium sulfate, potassium sulfate, ammonium sulfate, etc.

[0156] The above step (II) includes a step of adding the above aluminum compound, or at least one additive selected from the group consisting of the above aluminum compound, an amine, and a neutral salt to the hollow silica aqueous sol and heating, and then may include a step (II-iii) of contacting with a cation exchange resin, a step (II-iv) of adding an acid, or a combination thereof. The cation exchange resin is an H-type strongly acidic cation exchange resin, and it can also be contacted with an anion exchange resin thereafter. As the acid, inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid, or organic acids such as citric acid, acetic acid, malic acid, lactic acid, succinic acid, tartaric acid, butyric acid, fumaric acid, propionic acid, and formic acid can be added.

[0157] In the present invention, the above step (II) may include a step of adding the above aluminum compound (for example, sodium aluminate), heating at 100 to 240 ° C for 0.1 to 48 hours, and then adding an acid (for example, sulfuric acid, nitric acid, hydrochloric acid) and contacting with a cation exchange resin (II-v). The addition of the above acid is a leaching operation for eluting aluminum-containing components not doped into the particles and metal impurities contained in the particles into the liquid during the heating process, an operation for removing these metal-containing components with a cation exchange resin, and may further include a step (II-vi) of contacting with a cation exchange resin again after heat aging at 40 to 100 ° C for 0.1 to 48 hours.

[0158] After the completion of the above step (II), it may further include a step (III) of solvent substitution of the aqueous medium in the hollow silica sol with an alcohol having 1 to 10 carbon atoms, a ketone having 1 to 10 carbon atoms, an ether having 1 to 10 carbon atoms, or an ester having 1 to 10 carbon atoms.

[0159] After the completion of the above step (III), a step (IV) of further adding at least one silane compound selected from the group consisting of the above formulas (1), (2), and (3) and heating can be included.

[0160] After the completion of the above steps (III) and (IV), after the aqueous medium of the hollow silica sol is subjected to solvent substitution with an alcohol having 1 to 10 carbon atoms in step (III) after the completion of the above step (II), in step (IV), at least one silane compound selected from the group consisting of the above formulas (1), (2), and (3) is added and heated, and then, solvent substitution is further performed with a ketone having 1 to 10 carbon atoms, an ether having 1 to 10 carbon atoms, or an ester having 1 to 10 carbon atoms.

[0161] 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.

Examples

[0162] (Measurement of silica concentration) The hollow silica sol was precisely weighed in a crucible, heated and dried on a hot plate at a temperature about 10 °C higher than the boiling point of the dispersion medium to remove the solvent, and then the obtained silica gel was calcined at 1000 °C, the calcination residue was weighed, and the silica concentration was calculated. (Measurement of moisture) The moisture of the organic solvent-dispersed sol was measured by the Karl Fischer titration method. (Measurement of viscosity) Measurement was performed at 25 °C using a B-II type viscometer (manufactured by Toki Sangyo Co., Ltd.). (Measurement of pH) Measurement was performed at 25 °C using a pH meter (manufactured by Toa DKK Corporation). For organic solvents that can be arbitrarily mixed with water, such as methanol sol and propylene glycol monomethyl ether sol, measurement was performed using a solution obtained by mixing pure water and the sol at a mass ratio of 1:1. For organic solvent sols with low solubility in water, such as methyl ethyl ketone sol, pure water and methanol It was measured using a solution prepared by mixing the ruthenium and its organic solvent sol in a mass ratio of 1:1:1. (Measurement of the average particle diameter of hollow silica particles by DLS (Dynamic Light Scattering Method)) The hollow silica sol was diluted with a solvent using the hollow silica sol as a dispersion medium, and the average particle diameter of the hollow silica particles was measured using a dynamic light scattering particle size measuring device (Zetasizer Nano manufactured by Spectris). (Measurement of the specific surface area of hollow silica particles by BET (Nitrogen Gas Adsorption Method)) The cation component in the hollow silica sol was removed with an H-type cation exchange resin, the solvent was removed by heat treatment, and the dried product was pulverized in a mortar and further treated at 250 °C for 2 hours. The specific surface area of this dried and pulverized product was measured using a gas adsorption method specific surface area measuring device (Monosorb TM MS-22 manufactured by Quantachrome INSTRUMENTS) with a mixed gas of 30% N2 (nitrogen) and 70% He (helium) as a carrier gas and by the B.E.T. one-point method. (Measurement of the average primary particle diameter of hollow silica particles by TEM (Transmission Electron Microscope)) The particles in the hollow silica sol were photographed with a transmission electron microscope (JEM-F200 manufactured by JEOL Ltd.), and approximately 300 arbitrarily selected particles were binarized using an automatic image processing analyzer (LUZEX AP manufactured by Nireco Corporation), and the diameter obtained by converting the projected area into a circle was measured as the average primary particle diameter (HEYWOOD diameter) of the hollow silica particles. (Measurement of the amount of aluminum (B) present in the entire hollow silica particles / Dissolution method) The accurately weighed hollow silica sol was dried, the silica component was removed by treatment with a hydrofluoric acid solution, and the residue was dissolved in an aqueous nitric acid solution. The amount of aluminum in the obtained aqueous solution was measured with an ICP emission analyzer, and the ratio (Al2O3 (ppm) / SiO2) of the amount of aluminum present in the entire hollow silica particles in terms of Al2O3 to 1 g of SiO2 of the hollow silica was determined. (Measurement of the amount of aluminum (A) bound to the surface of hollow silica particles / Leaching method) The cation component in the hollow silica sol was removed with an H-type cation exchange resin, and the solvent was removed by heat treatment. The dried product was pulverized in a mortar and further treated at 250 °C for 2 hours. 0.2 g of the obtained powder was put into a polypropylene container (PP sample bottle 50 mL) containing 20 mL of a 0.1 mol / L (N / 10) nitric acid aqueous solution, and shaken vigorously by hand. Next, ultrasonic treatment was performed for 10 minutes with an ultrasonic cleaner (ASU CLEANER ASU-10M manufactured by AS ONE) to thoroughly mix the powder and the nitric acid aqueous solution. It was put into a 50 °C constant temperature bath and held for 17 hours. Then, the inner solution was cooled to room temperature, charged into a centrifugal ultrafiltration filter (Amicon Ultra-15, molecular weight cut-off 10,000), and the amount of aluminum in the filtrate obtained by centrifugation was measured with an ICP emission spectrometer. The ratio of the amount of aluminum bound to the surface of the hollow silica particles in terms of Al2O3 to 1 g of SiO2 of the hollow silica (Al2O3 (ppm) / SiO2) was determined. (Measurement of the surface charge amount of hollow silica particles) The hollow silica sol was added to and diluted with 10 mL of methanol so that the silica concentration became about 0.5 mass% to prepare a measurement sample. Using a particle charge meter (manufactured by Freytag Turbo Co., Ltd., product name PCD-06), a 0.001 mol / L (N / 1000) DADMAC solution (manufactured by Freytag Turbo Co., Ltd.) as a cation standard titrant, the titration value until the streaming potential of the measurement sample became zero was measured. The value converted per 1 g of the hollow silica particles by dividing the obtained titration value by the mass of silica contained in the measurement sample was defined as the surface charge amount (μeq / g-SiO2). Note that DADMAC represents diallyldimethylammonium chloride. (Calculation of the specific surface area ratio (C / D)) The BET specific surface area value was divided by the specific surface area value calculated assuming true spherical particles with a true density of 2.2 g / cm 3 from the TEM average particle size, and the resulting value was defined as the specific surface area ratio. (Measurement of the refractive index of hollow silica particles) It was measured by the following procedures 1) to 3). 1) Preparation of a hollow silica aqueous sol-containing varnish Weighed 20.00 g of 3-glycidoxypropyltrimethoxysilane (manufactured by Momentive, SILQUEST A-187T) into a plastic container, added 18.57 g of methanol and 4.57 g of 0.01 N hydrochloric acid aqueous solution thereto, and stirred at room temperature for 5 hours. Aluminum 2,4 -methanol solution of pentanedionate (Al(acac)3) (10% by mass Al(acac)3) 6.00 g was added as a curing agent and stirred for 10 minutes to prepare a partial hydrolyzate of 3-glycidoxypropyltrimethoxysilane (GPS) (concentration: 43% by mass). Weighed 25.00 g in total, with the final solvent composition being water / methanol = 9 / 1 by weight ratio, and the amount of SiO2 in the hollow silica aqueous sol being 50 phr, 100 phr, 150 phr. Weighed the prepared partial hydrolyzate of GPS, water, methanol, and 0.25 g of a methanol solution (10% by mass L-7604) of a leveling agent (DOWSIL trademark L-7604) into a brown bottle and stirred at room temperature for 30 minutes to prepare a varnish containing hollow silica aqueous sol (solid content concentration: 4% by mass, amount of SiO2 incorporated: 50 phr, 100 phr, 150 phr). 2) Preparation of a film containing hollow silica particles Approximately 1 mL of the varnish containing hollow silica aqueous sol (amount of incorporation (SiO2): 50 phr, 100 phr, 150 phr) obtained in 1) was dropped onto a Si substrate treated with UV-O3, and using a spin coater (Mikasa Co., Ltd., Opticoat MS-B100), it was uniformly spread on the Si substrate under the conditions of rising to 200 rpm in 2 seconds, 200 rpm × 10 seconds, rising to 800 rpm in 2 seconds, 800 rpm × 5 seconds, and descending to 0 rpm in 5 seconds. Then, it was baked on a hot plate at 80 °C for 5 minutes and heat-treated in an oven at 120 °C for 1 hour to prepare a film containing hollow silica particles (amount of SiO2 incorporated: 50 phr, 100 phr, 150 phr). 3) Measurement of the refractive index of the film containing hollow silica particles and calculation of the refractive index of the hollow silica particles The refractive indices of the hollow silica particle-containing films (SiO₂ content: 50 phr, 100 phr, 150 phr) obtained in (2) were measured using an ellipsometer (Variable Angle Spectroscopic Ellipsometer VASE manufactured by J. A. Woollam Japan Co., Ltd.). Separately, the refractive index of a film containing no hollow silica particles prepared in the same manner using only the partial hydrolyzate of GPS was also measured. The measured refractive indices of the composite films were plotted against the content of the hollow silica particles, and the refractive index of the hollow silica particles was determined by extrapolating so that the content of the hollow silica particles became 100% by mass.

[0163] (Example 1) (1) Preparation of an aqueous dispersion sol (a) of aluminum-containing hollow silica particles As a starting material, 2015 g of a commercially available aqueous hollow silica sol [manufactured by Ningbo Dilato, (trade name) HKT-A20-40 (heated at a temperature below 100 °C in an aqueous medium during the production of the aqueous hollow silica sol), 19.7 mass% SiO₂, pH 8.8, average particle diameter of 54 nm by the DLS method, specific surface area (C) of 145 m 2 / g, amount of aluminum bound to the particle surface (A) is 0.1 ppm in terms of Al₂O₃ per 1 g of SiO₂ of the hollow silica particles, ratio of the amount of aluminum present in the whole particle (B) in terms of Al₂O₃ per 1 g of SiO₂ of the hollow silica particles is 0.5 ppm, (A / B ratio) is 0.20, average primary particle diameter of 46 nm by TEM observation, TEM-converted specific surface area (D) of 59 m 2 / g, specific surface area ratio (C / D ratio) is 2.5, particle refractive index 1.30] was placed in a container and stirred, 169 g of diluted sodium aluminate (aqueous solution with a concentration of 1.0 mass% in terms of Al₂O₃) was added dropwise over 1 minute, and further 6 g of an aqueous sodium sulfate solution (aqueous solution with a concentration of 10 mass% in terms of Na₂SO₄) was added dropwise, followed by stirring for 30 minutes. 800 g of the above mixture was placed in a glass separable flask, heat-treated at 80 °C for 5 hours, and cooled to room temperature. Next, it was passed through a column-packed cation exchange resin (H-type Amberlite IR-120B) at a space velocity (SV) of 5 / hour to obtain an aqueous dispersion sol (a) of aluminum-containing hollow silica particles. Its physical properties were 16.9 mass% as SiO2, pH 2.6, average particle diameter of 54 nm by the DLS method, specific surface area (C) of 149 m 2 / g, the amount of aluminum (A) bound to the particle surface was 1500 ppm, the amount of aluminum (B) present in the whole particle was 1900 ppm, the (A / B ratio) was 0.79, the average primary particle diameter by TEM observation was 43 nm, the specific surface area (D) in terms of TEM was 63 m 2 / g, the specific surface area ratio (C / D ratio) was 2.4, the particle refractive index was 1.26, and the outer shell thickness was 6.7 nm. (2) Preparation of methanol dispersion sol (a1) of aluminum-containing hollow silica particles 118.3 g of the aqueous dispersion sol (a) of aluminum-containing hollow silica particles was placed in a 300 mL eggplant flask, and 15.0 g of methanol was further added. The pressure was reduced to 580 Torr using a rotary evaporator, and methanol substitution was carried out while heating to 120 °C to obtain a methanol dispersion sol (a1) of aluminum-containing hollow silica particles. Its physical properties were pH 3.7, average particle size of 64 nm by the DLS method, 24.2 mass% as SiO2, 0.3 mass% of water, viscosity of 1.9 mPa·sec, and surface charge amount of 59 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0164] (Example 2) (1) Preparation of aqueous dispersion sol (a) of aluminum-containing hollow silica particles An aqueous dispersion sol (a) of aluminum-containing hollow silica particles was obtained in the same manner as in Example 1. (2) Preparation of methanol dispersion sol (a2) of aluminum-containing hollow silica particles Into a 300 mL eggplant flask, 118.3 g of an aqueous dispersion sol (a) of aluminum-containing hollow silica particles was placed, and further 14.9 g of methanol and 0.1 g of diethanolamine (DEA) were added. Using a rotary evaporator, the pressure was reduced to 580 Torr, and methanol substitution was carried out while heating to 120 °C to obtain a methanol dispersion sol (a2) of aluminum-containing hollow silica particles. Its physical properties were pH 6.3, average particle diameter of 70 nm by the DLS method, 21.3 mass% as SiO2, 0.3 mass% of water, viscosity of 1.6 mPa·sec, and surface charge amount of 58 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0165] (Example 3) (1) Preparation of an aqueous dispersion sol (b) of aluminum-containing hollow silica particles As a starting material, 2015 g of a commercially available hollow silica aqueous sol (manufactured by Ningbo Dilato, (trade name) HKT-A20-40) was placed in a container and stirred. 169 g of diluted sodium aluminate (aqueous solution with a concentration of 1.0 mass% in terms of Al2O3) was added dropwise over 1 minute, and further 6 g of an aqueous sodium sulfate solution (aqueous solution with a concentration of 10 mass% in terms of Na2SO4) was added dropwise, followed by stirring for 30 minutes. 200 g of the above mixture was placed in a 300 mL-SUS autoclave container, and heat treatment was carried out at 150 °C for 5 hours and then cooled to room temperature. Next, it was passed through a column-packed cation exchange resin (H-type Amberlite IR-120B) at a space velocity (SV) of 5 / hour to obtain an aqueous dispersion sol (b) of aluminum-containing hollow silica particles. Its physical properties were 17.5 mass% as SiO2, pH 2.5, average particle diameter of 54 nm by the DLS method, specific surface area (C) of 147 m 2 / g by the BET method, amount of aluminum bound to the particle surface (A) of 2400 ppm, amount of aluminum present in the whole particle (B) of 3200 ppm, (A / B ratio) of 0.75, average primary particle diameter of 49 nm by TEM observation, TEM-converted specific surface area (D) of 56 m 2 / g, specific surface area ratio (C / D ratio) of 2.6, particle refractive index of 1.31, and outer shell thickness of 7.1 nm. (2) Preparation of a methanol dispersion sol (b1) of aluminum-containing hollow silica particles 114.2 g of an aqueous dispersion sol (b) of aluminum-containing hollow silica particles was placed in a 300 mL eggplant flask, and 19.2 g of methanol was further added. Using a rotary evaporator, the pressure was reduced to 580 Torr, and while heating to 120 °C, methanol substitution was performed to obtain a methanol dispersion sol (b1) of aluminum-containing hollow silica particles. Its physical properties were a pH of 4.9, an average particle diameter of 70 nm by the DLS method, 19.1 mass% as SiO2, 0.3 mass% of water, a viscosity of 1.7 mPa·sec, and a surface charge amount of 58 μeq / g in terms of 1 g of SiO2 of the hollow silica particles.

[0166] (Example 4) (1) Preparation of an aqueous dispersion sol (b) of aluminum-containing hollow silica particles It was adjusted in the same manner as in Example 3 to obtain an aqueous dispersion sol (b) of aluminum-containing hollow silica particles. (2) Preparation of a methanol dispersion sol (b2) of aluminum-containing hollow silica particles 114.2 g of an aqueous dispersion sol (b) of aluminum-containing hollow silica particles was placed in a 300 mL eggplant flask, and 19.1 g of methanol and 0.1 g of diethanolamine (DEA) were further added. Using a rotary evaporator, the pressure was reduced to 580 Torr, and while heating to 120 °C, methanol substitution was performed to obtain a methanol dispersion sol (b2) of aluminum-containing hollow silica particles. Its physical properties were a pH of 8.4, an average particle diameter of 68 nm by the DLS method, 19.6 mass% as SiO2, 0.3 mass% of water, a viscosity of 1.5 mPa·sec, and a surface charge amount of 64 μeq / g in terms of 1 g of SiO2 of the hollow silica particles.

[0167] (Example 5) (1) Preparation of an aqueous dispersion sol (c) of aluminum-containing hollow silica particles 2015 g of a commercially available aqueous sol of hollow silica (manufactured by Ningbo Dilato, trade name: HKT-A20-40) was placed in a container as a starting material, stirred, 169 g of diluted sodium aluminate (an aqueous solution with a concentration of 1.0 mass% in terms of Al2O3) was added dropwise over 1 minute, and further 6 g of an aqueous sodium sulfate solution (an aqueous solution with a concentration of 10 mass% in terms of Na2SO4) was added dropwise, followed by stirring for 30 minutes. 200 g of the above mixture was placed in a 300 mL SUS autoclave container, heat-treated at 240 °C for 5 hours, and cooled to room temperature. Next, it was passed through a column-packed cation exchange resin (H-type Amberlite IR-120B) at a space velocity (SV) of 5 / hour to obtain an aqueous dispersion sol (c) of aluminum-containing hollow silica particles. Its physical properties were 17.8 mass% as SiO2, pH 2.4, average particle diameter of 54 nm by the DLS method, specific surface area (C) of 110 m 2 / g, the amount of aluminum bound to the particle surface (A) of 1700 ppm, the amount of aluminum present in the whole particle (B) of 2500 ppm, (A / B ratio) of 0.68, average primary particle diameter of 53 nm by TEM observation, TEM-converted specific surface area (D) of 51 m 2 / g, specific surface area ratio (C / D ratio) of 2.1, particle refractive index of 1.39, and outer shell thickness of 9.5 nm. (2) Preparation of methanol dispersion sol (c1) of aluminum-containing hollow silica particles 112.7 g of the aqueous dispersion sol (c) of aluminum-containing hollow silica particles was placed in a 300 mL eggplant flask, and 20.7 g of methanol was further added. Methanol substitution was performed under reduced pressure to 580 Torr and heating to 120 °C using a rotary evaporator to obtain a methanol dispersion sol (c1) of aluminum-containing hollow silica particles. Its physical properties were pH 4.8, average particle diameter of 72 nm by the DLS method, 21.1 mass% as SiO2, 0.3 mass% of water, viscosity of 1.3 mPa·sec, and surface charge amount of 51 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0168] (Example 6) (1) Preparation of aqueous dispersion sol (c) of aluminum-containing hollow silica particles An aqueous dispersion sol (c) of aluminum-containing hollow silica particles was obtained in the same manner as in Example 5. (2) Preparation of methanol dispersion sol (c2) of aluminum-containing hollow silica particles Into a 300 mL eggplant flask, 112.7 g of an aqueous dispersion sol (c) of aluminum-containing hollow silica particles was placed, and further 20.6 g of methanol and 0.1 g of diethanolamine (DEA) were added. Using a rotary evaporator, the pressure was reduced to 580 Torr, and methanol substitution was carried out while heating to 120 °C to obtain a methanol dispersion sol (c2) of aluminum-containing hollow silica particles. Its physical properties were pH 3.2, average particle diameter of 67 nm by the DLS method, 21.8 mass% as SiO2, 0.2 mass% of water, viscosity of 1.2 mPa·sec, and surface charge amount of 43 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0169] (Example 7) (1) Preparation of an aqueous dispersion sol (d) of aluminum-containing hollow silica particles As a starting material, a commercially available hollow silica aqueous sol [manufactured by Ningbo Dilato, (trade name) HKT-A20-40D (the hollow silica aqueous sol having passed through a heating temperature of 100 °C to 240 °C in an aqueous medium), 20.0 mass% SiO2, pH 9.3, by the DLS method average particle diameter of 55 nm, the amount of aluminum (A) bonded to the particle surface is 0.1 ppm in terms of Al2O3 per 1 g of SiO2 of the hollow silica particles, the ratio of the amount of aluminum (B) present in the whole particle to 1 g of SiO2 of the hollow silica particles in terms of Al2O3 is 0.4 ppm, average primary particle diameter of 43 nm by TEM observation, specific surface area ratio (A / B) is 1.8, particle refractive index is 1.29] 1980 g was placed in a container and stirred, and 169 g of diluted sodium aluminate (an aqueous solution with a concentration of 1.0 mass% in terms of Al2O3) was added dropwise in 1 minute, and further 6 g of an aqueous sodium sulfate solution (an aqueous solution with a concentration of 10 mass% in terms of Na2SO4) was added dropwise, and the mixture was stirred for 30 minutes. 800 g of the above mixture was placed in a glass separable flask, refluxed at 80 °C for 5 hours, and cooled to room temperature. Next, it was passed through a column-packed cation exchange resin (H-type Amberlite IR-120B) at a space velocity (SV) of 5 / hour to obtain an aqueous dispersion sol (d) of aluminum-containing hollow silica particles. Its physical properties were 18.5 mass% as SiO2, pH 2.3, average particle diameter of 55 nm by the DLS method, specific surface area (C) of 116 m2 / g, the amount of aluminum (A) bound to the particle surface is 1100 ppm, the amount of aluminum (B) present in the whole particle is 1400 ppm, the (A / B ratio) is 0.79, the average primary particle diameter by TEM observation is 47 nm, and the TEM-converted specific surface area (D) is 58 m 2 / g, the specific surface area ratio (C / D ratio) is 2.0, the particle refractive index is 1.27, and the outer shell thickness is 6.2 nm. (2) Preparation of methanol dispersion sol (d1) of aluminum-containing hollow silica particles Into a 300 mL eggplant flask, 107.9 g of an aqueous dispersion sol (d) of aluminum-containing hollow silica particles was placed, and 25.5 g of methanol was further added. Using a rotary evaporator, the pressure was reduced to 580 Torr, and while heating to 120 °C, methanol substitution was performed to obtain a methanol dispersion sol (d1) of aluminum-containing hollow silica particles. Its physical properties were pH 4.9, average particle diameter by the DLS method of 78 nm, 19.8 mass% as SiO2, 0.2 mass% of water, viscosity of 1.5 mPa·sec, and surface charge amount of 45 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0170] (Example 8) (1) Preparation of aqueous dispersion sol (d) of aluminum-containing hollow silica particles It was adjusted in the same manner as in Example 7 to obtain an aqueous dispersion sol (d) of aluminum-containing hollow silica particles. (2) Preparation of aluminum-containing hollow silica methanol sol (d2) Into a 300 mL eggplant flask, 107.9 g of an aqueous dispersion sol (d) of aluminum-containing hollow silica particles was placed, and 25.4 g of methanol and 0.1 g of diethanolamine (DEA) were further added. Using a rotary evaporator, the pressure was reduced to 580 Torr, and while heating to 120 °C, methanol substitution was performed to obtain a methanol dispersion sol (d2) of aluminum-containing hollow silica particles. Its physical properties were pH 8.3, average particle diameter by the DLS method of 72 nm, 21.7 mass% as SiO2, 0.3 mass% of water, viscosity of 1.6 mPa·sec, and surface charge amount of 58 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0171] (Example 9) (1) Preparation of Aluminum-Containing Hollow Silica Aqueous Dispersion Sol (e) Put 1980 g of commercially available hollow silica aqueous sol (manufactured by Ningbo Dilato, trade name: HKT-A20-40D) as the starting material into a container, stir, and drop 169 g of diluted sodium aluminate (an aqueous solution with a concentration of 1.0% by mass in terms of Al2O3) over 1 minute. Then, drop 6 g of an aqueous sodium sulfate solution (an aqueous solution with a concentration of 10% by mass in terms of Na2SO4), and stir for 30 minutes. Put 200 g of the above mixture into a 300 mL-SUS autoclave container, perform a heat treatment at 150 °C for 5 hours, and cool to room temperature. Next, pass the solution through a column-packed cation exchange resin (H-type Amberlite IR-120B) at a space velocity (SV) of 5 / hour to obtain an aqueous dispersion sol (e) of aluminum-containing hollow silica particles. Its physical properties are 17.8% by mass as SiO2, pH 2.3, average particle diameter of 56 nm by the DLS method, specific surface area (C) of 115 m 2 / g, amount of aluminum (A) bound to the particle surface of 1500 ppm, amount of aluminum (B) present in the whole particle of 2500 ppm, (A / B ratio) of 0.60, average primary particle diameter of 48 nm by TEM observation, TEM-converted specific surface area (D) of 57 m 2 / g, specific surface area ratio (C / D ratio) of 2.0, particle refractive index of 1.28, and outer shell thickness of 6.0 nm. (2) Preparation of Methanol Dispersion Sol (e1) of Aluminum-Containing Hollow Silica Particles Put 112.5 g of the aqueous dispersion sol (e) of aluminum-containing hollow silica particles into a 300 mL eggplant flask, and add 20.8 g of methanol. Perform methanol substitution under reduced pressure to 580 Torr and heating to 120 °C using a rotary evaporator to obtain a methanol dispersion sol (e1) of aluminum-containing hollow silica particles. Its physical properties are pH 4.6, average particle diameter of 69 nm by the DLS method, 16.8% by mass as SiO2, water content of 0.9% by mass, viscosity of 1.3 mPa·sec, and surface charge amount of 63 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0172] (Example 10) (1) Preparation of aqueous dispersion sol (e) of aluminum-containing hollow silica particles In the same manner as in Example 9, an aqueous dispersion sol (e) of aluminum-containing hollow silica particles was obtained. (2) Preparation of methanol dispersion sol (e2) of aluminum-containing hollow silica particles 112.5 g of the aqueous dispersion sol (e) of aluminum-containing hollow silica particles was placed in a 300 mL eggplant flask, and 20.7 g of methanol and 0.1 g of diethanolamine (DEA) were further added. Methanol substitution was carried out under reduced pressure to 580 Torr and heating to 120 °C using a rotary evaporator to obtain a methanol dispersion sol (e2) of aluminum-containing hollow silica particles. Its physical properties were pH 8.2, average particle diameter of 70 nm by the DLS method, 17.4 mass% as SiO2, 0.3 mass% of water, viscosity of 1.4 mPa·sec, and surface charge amount of 64 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0173] (Example 11) (1) Preparation of aqueous dispersion sol (f) of aluminum-containing hollow silica particles 1980 g of a commercially available aqueous hollow silica sol (manufactured by Ningbo Dilato, (trade name) HKT-A20-40D) was placed in a container as a starting material, stirred, and 169 g of diluted sodium aluminate (aqueous solution with a concentration of 1.0 mass% in terms of Al2O3) was added dropwise over 1 minute. Further, 6 g of an aqueous sodium sulfate solution (aqueous solution with a concentration of 10 mass% in terms of Na2SO4) was added dropwise, and the mixture was stirred for 30 minutes. 200 g of the above mixture was placed in a 300 mL-SUS autoclave container, heat-treated at 240 °C for 5 hours, and cooled to room temperature. Next, it was passed through a column-packed cation exchange resin (H-type Amberlite IR-120B) at a space velocity (SV) of 5 / hour to obtain an aqueous dispersion sol (f) of aluminum-containing hollow silica particles. Its physical properties were 18.0 mass% as SiO2, pH 2.5, average particle diameter of 57 nm by the DLS method, and specific surface area (C) of 116 m by the BET method 2 / g, the amount of aluminum (A) bound to the particle surface is 1700 ppm, the amount of aluminum (B) present in the whole particle is 3500 ppm, the (A / B ratio) is 0.49, the average primary particle size by TEM observation is 42 nm, and the TEM-converted specific surface area (D) is 65 m 2 / g, the specific surface area ratio (C / D ratio) is 1.8, the particle refractive index is 1.30, and the outer shell thickness is 6.4 nm. (2) Preparation of methanol dispersion sol (f1) of aluminum-containing hollow silica particles Into a 300 mL eggplant flask, 110.9 g of the aqueous dispersion sol (f) of aluminum-containing hollow silica particles was placed, and 22.5 g of methanol was further added. Using a rotary evaporator, the pressure was reduced to 580 Torr, and while heating to 120 °C, methanol substitution was carried out to obtain a methanol dispersion sol (f1) of aluminum-containing hollow silica particles. Its physical properties were pH 3.2, average particle size by the DLS method of 70 nm, 25.6 mass% as SiO2, 0.4 mass% of water, viscosity of 2.2 mPa·sec, and surface charge amount of 51 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0174] (Example 12) (1) Preparation of aqueous dispersion sol (f) of aluminum-containing hollow silica particles It was adjusted in the same manner as in Example 11 to obtain an aqueous dispersion sol (f) of aluminum-containing hollow silica particles. (2) Preparation of methanol dispersion sol (f2) of aluminum-containing hollow silica particles Into a 300 mL eggplant flask, 110.9 g of the aqueous dispersion sol (f) of aluminum-containing hollow silica particles was placed, and 22.4 g of methanol and 0.1 g of diethanolamine (DEA) were further added. Using a rotary evaporator, the pressure was reduced to 580 Torr, and while heating to 120 °C, methanol substitution was carried out to obtain a methanol dispersion sol (f2) of aluminum-containing hollow silica particles. Its physical properties were pH 3.6, average particle size by the DLS method of 70 nm, 16.9 mass% as SiO2, 0.6 mass% of water, viscosity of 1.2 mPa·sec, and surface charge amount of 61 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0175] (Example 13) (1) Preparation of methanol dispersion sol (d2) of aluminum-containing hollow silica particles In the same manner as in Example 8, a methanol dispersion sol (d2) of aluminum-containing hollow silica particles was obtained. (2) Preparation of methyl ethyl ketone (MEK) dispersion sol (d3) of silane-treated aluminum-containing hollow silica particles 35.35 g of the methanol dispersion sol (d2) of aluminum-containing hollow silica particles prepared in Example 8 was placed in a 300 mL eggplant flask, 10.93 g of methanol and 0.38 g of water were added and stirred, and further 0.34 g of 3-(methacryloyloxy)propyltrimethoxysilane (MPS, manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-503) was added. While stirring, reflux treatment was carried out at 72 °C for 5 hours. Then, it was cooled to room temperature, and under reduced pressure to 250 Torr with a rotary evaporator, and MEK substitution was carried out while heating at 75 °C to obtain a MEK dispersion sol (d3) of silane-treated aluminum-containing hollow silica particles. Its physical properties were pH 6.0, average particle diameter of 77 nm by the DLS method, 14.9 mass% as SiO2, 0.1 mass% of moisture, viscosity of 6.3 mPa·sec, and surface charge amount of 51 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0176] (Example 14) (1) Preparation of methanol dispersion sol (e2) of aluminum-containing hollow silica particles In the same manner as in Example 10, a methanol dispersion sol (e2) of aluminum-containing hollow silica particles was obtained. (2) Preparation of methyl ethyl ketone (MEK) dispersion sol (e3) of silane-treated aluminum-containing hollow silica particles 35.71 g of the methanol-dispersed sol (e2) of aluminum-containing hollow silica particles prepared in Example 10 was placed in a 300 mL eggplant flask, 4.29 g of methanol and 0.09 g of water were added and stirred, and further 0.28 g of 3-(methacryloyloxy)propyltrimethoxysilane (MPS, manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-503) was added, and reflux treatment was carried out at 72 °C for 5 hours while stirring. Then, it was cooled to room temperature, and under reduced pressure to 250 Torr with a rotary evaporator, and while heating to 75 °C, MEK substitution was carried out to obtain a MEK-dispersed sol (e3) of silane-treated aluminum-containing hollow silica particles. Its physical properties were pH 5.8, average particle size of 88 nm by the DLS method, 12.4 mass% as SiO2, 0.2 mass% of water, viscosity of 6.3 mPa·sec, and surface charge amount of 60 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0177] (Example 15) (1) Preparation of aluminum-containing hollow silica aqueous dispersion sol (g) 2500.0 g of a commercially available hollow silica aqueous sol (manufactured by Ningbo Dilato, (product name) HKT-A20-40D) was placed in a container, stirred, and 42.5 g of dilute sodium aluminate (aqueous solution with a concentration of 1.0 mass% in terms of Al2O3) was added dropwise over 1 minute and stirred for 60 minutes. 2537.6 g of the above mixture was placed in a 3 L-SUS autoclave container, heat-treated at 150 °C for 5 hours, and cooled to room temperature. Further, 6.1 g of 8% sulfuric acid was added with stirring and stirred for 1 hour, and passed through a column-packed cation exchange resin (H-type Amberlite IR-120B) at a space velocity (SV) of 5 / hour to obtain an aqueous sol A with 18.9 mass% as SiO2 and pH 2.4. The aqueous sol A was heat-treated at 80 °C for 10 hours, cooled to room temperature over 8 hours, and then passed through a column-packed cation exchange resin (H-type Amberlite IR-120B) at a space velocity (SV) of 5 / hour to obtain an aqueous dispersion sol (g) of aluminum-containing hollow silica particles. Its physical properties were 17.0 mass% as SiO2, pH 2.3, average particle diameter of 54 nm by the DLS method, specific surface area (C) of 116 m2 / g, the amount of aluminum (A) bound to the particle surface is 560 ppm, the amount of aluminum (B) present in the whole particle is 700 ppm, the (A / B ratio) is 0.60, the average primary particle size by TEM observation is 43 nm, and the TEM-converted specific surface area (D) is 63 m 2 / g, the specific surface area ratio (C / D ratio) is 1.8, the particle refractive index is 1.27, and the outer shell thickness is 6.0 nm. (2) Preparation of methanol-dispersed sol (g1) of aluminum-containing hollow silica particles 690.4 g of an aqueous dispersion sol (g) of aluminum-containing hollow silica particles was placed in a 2 L eggplant flask, and 68.1 g of methanol was further added. Methanol substitution was carried out under reduced pressure to 580 Torr and heating to 120 °C to obtain a methanol-dispersed sol (g1) of aluminum-containing hollow silica particles. Its physical properties were pH 3.3, average particle size by DLS method 73 nm, 27.4 mass% as SiO2, water content 0.5 mass%, viscosity 1.6 mPa·sec, and surface charge amount 38 μeq / g converted per 1 g of SiO2 of the hollow silica particles. When methanol was added to adjust it to 20.5 mass% as SiO2, the physical properties were pH 3.5, water content 0.5 mass%, and viscosity 1.2 mPa·sec. (3) Preparation of methyl ethyl ketone (MEK)-dispersed sol (g1) of silane-treated aluminum-containing hollow silica particles 123.8 g (20.5% by mass as SiO2) of the methanol dispersion sol (g1) of aluminum-containing hollow silica particles was placed in a 500 mL eggplant flask, 44.3 g of methanol and 1.3 g of water were added and stirred, and 1.27 g of 3-(methacryloyloxy)propyltrimethoxysilane (MPS, Shin-Etsu Chemical Co., Ltd., product name KBM-503) was added, and reflux treatment was performed for 5 hours at 72 ° C. while stirring. After that, it was cooled to room temperature, and MEK replacement was performed in a rotary evaporator while reducing the pressure to 400 Torr and heating to 75 ° C., and a MEK dispersion sol (g1) of silane-treated aluminum-containing hollow silica particles was obtained. Its physical properties were pH 3.8, average particle size by DLS method 66 nm, 22.3% by mass as SiO2, 0.02% by mass moisture, and surface charge amount converted per 1 g of SiO2 of hollow silica particles 43 μeq / g. MEK was added to this and the SiO2 content was adjusted to 20.5 mass%, resulting in a pH of 3.8, a moisture content of 0.02 mass%, and a viscosity of 1.5 mPa·sec.

[0178] Example 16 (1) Preparation of methanol dispersion sol of aluminum-containing hollow silica particles (i1) The same treatment as in Example 15 was carried out, except that the aqueous sol A was heated at 80°C for 10 hours and cooled to room temperature over 1 hour. That is, a commercially available hollow silica aqueous sol (manufactured by Ningbo Dilato, (product name) HKT-A20-40D) was used as the starting material, and an aluminum-containing hollow silica aqueous sol produced by a method that did not add an aqueous sodium sulfate solution during doping of aluminum atoms with an aqueous sodium aluminate solution was further solvent-substituted with methanol to obtain a methanol-dispersed sol of aluminum-containing hollow silica particles (i1). The physical properties of the product were pH 3.5, average particle size 72 nm by DLS method, and mass % of SiO2 23.5. The hollow silica particles had a surface charge of 52 μeq / g, calculated per 1 g of SiO2, with methanol added to give a SiO2 content of 20.5%. The physical properties of the mixture, when adjusted to 20.5% by mass as SiO2, were pH 3.6, water content 0.3% by mass, and viscosity 1.2 mPa sec. (2) Preparation of methanol dispersion sol (i2) of silane-treated aluminum-containing hollow silica particles 151.2 g of methanol dispersion sol (i1) of aluminum-containing hollow silica particles (20.5 mass% as SiO2) was placed in a 500 mL eggplant flask, 45.9 g of methanol and 1.55 g of water were added and stirred, and further 1.35 g of 3-(acryloyloxy)propyltrimethoxysilane (AcPS, manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-5103) was added, and reflux treatment was carried out at 72 °C for 5 hours while stirring. Then, it was cooled to room temperature to prepare a methanol dispersion sol (i2) of silane-treated aluminum-containing hollow silica particles. Its physical properties were pH 3.7, average particle diameter of 72 nm by the DLS method, 15.6 mass% as SiO2, 1.0 mass% of water, viscosity of 1.1 mPa·sec, and surface charge amount of 56 μeq / g converted per 1 g of SiO2 of the hollow silica particles.

[0179] (Example 17) (1) Preparation of methanol dispersion sol (j1) of aluminum-containing hollow silica particles The same treatment as in Example 15 was carried out except that the aqueous sol A was heat-treated at 80 °C for 10 hours and cooled to room temperature over 2.5 hours. That is, a commercially available hollow silica aqueous sol (manufactured by Ningbo Dilato, trade name HKT-A20-40D) was used as a starting material, and an aluminum-containing hollow silica aqueous sol produced by a method in which an aqueous sodium sulfate solution was not added during the doping of aluminum atoms with an aqueous sodium aluminate solution was further solvent-exchanged with methanol to obtain a methanol dispersion sol (j1) of aluminum-containing hollow silica particles. Its physical properties were pH 3.4, average particle diameter of 69 nm by the DLS method, 20.5 mass% as SiO2, 0.6 mass% of water, viscosity of 1.2 mPa·sec, and surface charge amount of 47 μeq / g converted per 1 g of SiO2 of the hollow silica particles. (2) Preparation of methanol dispersion sol (j2) of silane-treated aluminum-containing hollow silica particles 151.2 g of a methanol dispersion sol (j1) of aluminum-containing hollow silica particles (20.5 mass% as SiO2) was placed in a 500 mL eggplant flask, 46.3 g of methanol and 1.09 g of water were added and stirred, and further 1.43 g of 3-(methacryloyloxy)propyltrimethoxysilane (MPS, manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-503) was added, and reflux treatment was carried out at 72 °C for 5 hours while stirring. Then, it was cooled to room temperature to prepare a methanol dispersion sol (j2) of silane-treated aluminum-containing hollow silica particles. Its physical properties were pH 3.6, average particle diameter of 70 nm by the DLS method, 16.3 mass% as SiO2, and 1.0 mass% of moisture content.

[0180] (Example 18) (1) Preparation of an aqueous dispersion sol (k) of aluminum-containing hollow silica 200 g of a commercially available aqueous sol of hollow silica (manufactured by Ningbo Dilato, trade name HKT-A20-40D) was placed in a container and stirred, and 40.0 g of diluted sodium aluminate (aqueous solution with a concentration of 1.0 mass% in terms of Al2O3) was added dropwise over 1 minute, and further 0.59 g of an aqueous sodium sulfate solution (aqueous solution with a concentration of 10 mass% in terms of Na2SO4) was added dropwise, and the mixture was stirred for 30 minutes. 240 g of the above mixture was placed in a 300 mL-SUS autoclave container, heat-treated at 150 °C for 5 hours, and cooled to room temperature. Next, it was passed through a column-packed cation exchange resin (H-type Amberlite IR-120B) at a space velocity (SV) of 5 / hour to obtain an aqueous dispersion sol (k) of aluminum-containing hollow silica particles. Its physical properties were 16.9 mass% as SiO2, pH 2.6, average particle diameter of 56 nm by the DLS method, specific surface area (C) of 115 m 2 / g, the amount of aluminum (B) present in the whole particles was 4500 ppm, the average primary particle diameter by TEM observation was 48 nm, the specific surface area (D) in terms of TEM was 57 m 2 / g, the specific surface area ratio (C / D ratio) was 2.0, the particle refractive index was 1.28, and the outer shell thickness was 6.0 nm. (2) Preparation of a methanol dispersion sol (k1) of aluminum-containing hollow silica particles 118.3 g of an aqueous dispersion sol (k) of aluminum-containing hollow silica particles was placed in a 300 mL eggplant flask, and 10.7 g of methanol was further added. Using a rotary evaporator, the pressure was reduced to 580 Torr, and methanol substitution was performed while heating to 120 °C to obtain a methanol dispersion sol (k1) of aluminum-containing hollow silica particles. Its physical properties were pH 3.5, an average particle diameter of 72 nm by the DLS method, 0.5 mass% water, and a surface charge amount of 46 μeq / g in terms of 1 g of SiO2 of the hollow silica particles.

[0181] (Example 19) (1) Preparation of an aqueous dispersion sol (m) of aluminum-containing hollow silica 200 g of a commercially available aqueous sol of hollow silica (manufactured by Ningbo Dilato, (trade name) HKT-A20-40D) was placed in a container and stirred. 80.0 g of diluted sodium aluminate (an aqueous solution with a concentration of 1.0 mass% in terms of Al2O3) was added dropwise over 1 minute, and further 0.59 g of an aqueous sodium sulfate solution (an aqueous solution with a concentration of 10 mass% in terms of Na2SO4) was added dropwise, followed by stirring for 30 minutes. 240 g of the above mixture was placed in a 300 mL SUS autoclave container, and heat treatment was performed at 150 °C for 5 hours and then cooled to room temperature. Next, it was passed through a column-packed cation exchange resin (H-type Amberlite IR-120B) at a space velocity (SV) of 5 / hour to obtain an aqueous dispersion sol (m) of aluminum-containing hollow silica particles. Its physical properties were 13.8 mass% as SiO2, pH 2.8, an average particle diameter of 68 nm by the DLS method, a specific surface area (C) of 115 m 2 / g, the amount of aluminum (B) present in the whole particles of 6200 ppm, an average primary particle diameter of 48 nm by TEM observation, a TEM-converted specific surface area (D) of 57 m 2 / g, a specific surface area ratio (C / D ratio) of 2.0, a particle refractive index of 1.28, and an outer shell thickness of 6.0 nm. (2) Preparation of a methanol dispersion sol (m1) of aluminum-containing hollow silica particles Into a 300 mL eggplant flask, 144.9 g of an aqueous dispersion sol (m) of aluminum-containing hollow silica particles was placed, and 5.0 g of methanol was further added. Using a rotary evaporator, the pressure was reduced to 580 Torr, and while heating to 120 °C, methanol substitution was carried out to obtain a methanol dispersion sol (m1) of aluminum-containing hollow silica particles. Its physical properties were pH 3.7, an average particle diameter of 82 nm by the DLS method, 0.5 mass% water, and a surface charge amount of 59 μeq / g in terms of per 1 g of SiO2 of the hollow silica particles.

[0182] (Example 20) (1) Preparation of an aqueous dispersion sol (n) of aluminum-containing hollow silica As a starting material, 2500.1 g of a commercially available aqueous sol of hollow silica (manufactured by Ningbo Dilato, (trade name) HKT-A20-40D, 20.8 mass% as SiO2) was placed in a container and stirred. 44.2 g of diluted sodium aluminate (an aqueous solution with a concentration of 1.0 mass% in terms of Al2O3) was added dropwise over 1 minute and stirred for 60 minutes. 2487.5 g of the above mixture was placed in a 3 L-SUS autoclave container and heat-treated at 150 °C for 5 hours, then cooled to room temperature to obtain an aqueous dispersion sol (n) of aluminum-containing hollow silica particles. Its physical properties were 20.1 mass% as SiO2, pH 10.1, an average particle diameter of 51 nm by the DLS method, a specific surface area (C) of 126 m 2 / g by the BET method, an average primary particle diameter of 45 nm by TEM observation, a TEM-converted specific surface area (D) of 61 m 2 / g, a specific surface area ratio (C / D ratio) of 2.1, a particle refractive index of 1.26, and an outer shell thickness of 5.0 nm. (2) Preparation of a methanol dispersion sol (n1) of aluminum-containing hollow silica particles Into a 300 mL eggplant flask, 74.2 g of an aqueous dispersion sol (n) of aluminum-containing hollow silica particles was placed, and 21.9 g of methanol was further added. Using a rotary evaporator, the pressure was reduced to 580 Torr, and while heating to 120 °C, methanol substitution was carried out to obtain a methanol dispersion sol (n1) of aluminum-containing hollow silica particles. Its physical properties were pH 5. 6. The average particle size was 77 nm by the DLS method, 20.5% by mass as SiO₂, 0.7% by mass of water, the viscosity was 1.6 mPa·sec, and the surface charge amount per 1 g of SiO₂ of the hollow silica particles was 38 μeq / g.

[0183] (Example 21) (1) Preparation of an aqueous dispersion sol (p) of aluminum-containing hollow silica The same treatment as in Example 15 was carried out. That is, a commercially available hollow silica aqueous sol (manufactured by Ningbo Dilato, (trade name) HKT-A20-40D) was used as a starting material, and an aqueous dispersion sol (p) of aluminum-containing hollow silica particles was produced by a method in which an aqueous sodium sulfate solution was not added during the doping of aluminum atoms with an aqueous sodium aluminate solution. Its physical properties were 17.7% by mass as SiO₂, pH 2.3, the average particle size was 54 nm by the DLS method, the specific surface area (C) by the BET method was 116 m 2 / g, the average primary particle size by TEM observation was 43 nm, the TEM-converted specific surface area (D) was 63 m 2 / g, the specific surface area ratio (C / D ratio) was 1.8, the particle refractive index was 1.27, and the thickness of the outer shell was 6.0 nm. (2) Preparation of a propylene glycol monomethyl ether (PGME) dispersion sol (p3) of aluminum-containing hollow silica particles 712.0 g of an aqueous dispersion sol (p) of aluminum-containing hollow silica particles was placed in a 2 L eggplant flask, and 99.0 g of PGME was further added. The PGME substitution was carried out under reduced pressure to 70 Torr and heating at 70 °C using a rotary evaporator to obtain an aluminum-containing hollow silica particle PGME dispersion sol (p3). Its physical properties were pH 3.7, the average particle size was 73 nm by the DLS method, 21.2% by mass as SiO₂, 0.1% by mass of water, the viscosity was 4.0 mPa·sec, and the surface charge amount per 1 g of SiO₂ of the hollow silica particles was 37 μeq / g.

[0184] (Example 22) (1) Preparation of a methanol dispersion sol (q1) of aluminum-containing hollow silica particles The aqueous sol A was heat-treated at 80 °C for 10 hours and cooled to room temperature over 4 hours, and the same treatment as in Example 15 was carried out. That is, a commercially available hollow silica aqueous sol (manufactured by Ningbo Dilato, trade name HKT-A20-40D) was used as the starting material, and an aluminum-containing hollow silica aqueous sol produced by a method in which an aqueous sodium sulfate solution was not added during the doping of aluminum atoms with an aqueous sodium aluminate solution was further subjected to solvent substitution with methanol to obtain a methanol dispersion sol (q1) of aluminum-containing hollow silica particles. Its physical properties were pH 3.4, an average particle diameter of 69 nm by the DLS method, 21.5% by mass as SiO2, 0.2% by mass of water, a viscosity of 1.2 mPa·sec, and a surface charge amount of 40 μeq / g converted per 1 g of SiO2 of the hollow silica particles. (2) Preparation of propylene glycol monomethyl ether acetate (PGMEA) dispersion sol (q4) of silane-treated aluminum-containing hollow silica particles 50.00 g (20.5% by mass as SiO2) of the methanol dispersion sol (q1) of aluminum-containing hollow silica particles was placed in a 300 mL eggplant flask, 18.35 g of methanol and 0.54 g of water were added and stirred, and further 0.39 of 3-mercaptopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-803) was added, and reflux treatment was carried out at 72 °C for 5 hours while stirring. Then, it was cooled to room temperature, and under reduced pressure to 80 Torr with a rotary evaporator, and PGMEA substitution was carried out while heating to 75 °C to obtain a PGMEA dispersion sol (q4) of silane-treated aluminum-containing hollow silica particles. Its physical properties were pH 3.9, an average particle diameter of 84 nm by the DLS method, 15.9% by mass as SiO2, 0.2% by mass of water, a surface charge amount of 38 μeq / g converted per 1 g of SiO2 of the hollow silica particles, and 0.7% by mass of MeOH.

[0185] (Example 23) (1) Preparation of methanol dispersion sol (r1) of aluminum-containing hollow silica particles The aqueous sol A was heat-treated at 80 °C for 10 hours and cooled to room temperature over 4 hours, and the same treatment as in Example 15 was carried out. That is, a commercially available hollow silica aqueous sol (manufactured by Ningbo Dilato, trade name HKT-A20-40D) was used as the starting material, and an aluminum-containing hollow silica aqueous sol produced by a method in which an aqueous sodium sulfate solution was not added during the doping of aluminum atoms with an aqueous sodium aluminate solution was further subjected to solvent substitution with methanol to obtain a methanol dispersion sol (r1) of aluminum-containing hollow silica particles. Its physical properties were pH 3.4, an average particle diameter of 69 nm by the DLS method, 21.5% by mass as SiO2, 0.2% by mass of water, a viscosity of 1.2 mPa·sec, and a surface charge amount of 40 μeq / g converted per 1 g of SiO2 of the hollow silica particles. (2) Preparation of propylene glycol monomethyl ether acetate (PGMEA) dispersion sol (r5) of silane-treated aluminum-containing hollow silica particles 49.92 g (20.5% by mass as SiO2) of the methanol dispersion sol (r1) of aluminum-containing hollow silica particles was placed in a 300 mL eggplant flask, 18.44 g of methanol and 0.54 g of water were added and stirred, and further 0.64 of hexamethyldisiloxane (HMDSO, manufactured by Shin-Etsu Chemical Co., Ltd., trade name KF-96L-0.65CS) was added, and reflux treatment was carried out at 60 °C for 2 hours while stirring. Then, it was cooled to room temperature, and under reduced pressure to 400 Torr with a rotary evaporator, and while heating to 75 °C, 40 g of PGMEA was charged and treated until 34 g of the distillate was obtained. 0.64 g of HMDSO was added, and reflux treatment was carried out at 60 °C for 2 hours while stirring. Then, it was cooled to room temperature, and under reduced pressure to 80 Torr with a rotary evaporator, and while heating to 75 °C, 20 g of PGMEA was charged and treated until 26 g of the distillate was obtained, to obtain a PGMEA dispersion sol (r5) of silane-treated aluminum-containing hollow silica particles. Its physical properties were pH 4.0, an average particle diameter of 77 nm by the DLS method, 16.9% by mass as SiO2, 0.1% by mass of water, a surface charge amount of 34 μeq / g converted per 1 g of SiO2 of the hollow silica particles, and 0.2% by mass of MeOH.

[0186] (Example 24) (1) Preparation of aluminum-containing hollow silica aqueous dispersion sol (s) 2500.0 g of commercially available hollow silica aqueous sol (manufactured by Ningbo Dilato, trade name: HKT-A20-40D) was placed in a container as a starting material, stirred, and 5.0 g of diluted sodium aluminate (an aqueous solution with a concentration of 1.0% by mass in terms of Al2O3) was added dropwise over 1 minute, followed by stirring for 60 minutes. 2500.0 g of the above mixture was placed in a 3L-SUS autoclave container, heat-treated at 150 °C for 5 hours, cooled to room temperature, and a stable alkaline aluminum-containing hollow silica aqueous dispersion sol (s) was obtained. The amount of aluminum (A) bound to the particle surface was 100 ppm.

[0187] (Comparative Example 1) 2015 g of commercially available hollow silica aqueous sol (manufactured by Ningbo Dilato, trade name: HKT-A20-40) was placed in a container as a starting material, stirred, and 169 g of diluted sodium aluminate (an aqueous solution with a concentration of 1.0% by mass in terms of Al2O3) was added dropwise over 1 minute. Further, 6 g of an aqueous sodium sulfate solution (an aqueous solution with a concentration of 10% by mass in terms of Na2SO4) was added dropwise, and the mixture was stirred at room temperature (20 °C) for 30 minutes. Without heat treatment, when the solution was passed through a column-packed cation exchange resin (H-type Amberlite IR-120B) at a space velocity (SV) of 5 / hour, gelation occurred in the column, and a desired aqueous dispersion sol of aluminum-containing hollow silica particles could not be obtained.

[0188] (Comparative Example 2) 198 g of commercially available hollow silica aqueous sol (manufactured by Ningbo Dilato, trade name: HKT-A20-40D) was placed in a container as a starting material, stirred, and 169 g of diluted sodium aluminate (an aqueous solution with a concentration of 1.0% by mass in terms of Al2O3) was added dropwise over 1 minute. Further, 6 g of an aqueous sodium sulfate solution (an aqueous solution with a concentration of 10% by mass in terms of Na2SO4) was added dropwise, and the mixture was stirred at room temperature (20 °C) for 30 minutes. When the column was filled with cation exchange resin (H-type Amberlite IR-120B) without heat treatment and liquid was passed through it at a space velocity (SV) of 5 / hour, gelation occurred inside the column, and a desired aqueous dispersion sol of aluminum-containing hollow silica particles could not be obtained.

[0189] (Comparative Example 3) (1) Preparation of aluminum-containing hollow silica aqueous dispersion sol (l) 2500.0 g of commercially available hollow silica aqueous sol (manufactured by Ningbo Dilato, (trade name) HKT-A20-40D) was placed in a container as a starting material, stirred, and 2.5 g of sodium aluminate solution diluted (aqueous solution with a concentration of 1.0% by mass in terms of Al2O3) was added dropwise over 1 minute and stirred for 60 minutes. 2500.0 g of the above mixture was placed in a 3 L-SUS autoclave container, heat-treated at 150 °C for 5 hours, and cooled to room temperature. The amount of aluminum (A) bound to the particle surface was 50 ppm. Further, 6.1 g of 8% sulfuric acid was added with stirring and stirred for 1 hour. When trying to pass the solution through a column filled with cation exchange resin (H-type Amberlite IR-120B) at a space velocity (SV) of 5 / hour, the column became blocked halfway and an aqueous sol could not be obtained.

Industrial Applicability

[0190] It is a hollow silica particle in which aluminum atoms are bonded to the surface of the hollow silica particle at a specific ratio in terms of Al2O3, and a hollow silica sol for mixing the hollow silica particle with an organic solvent and a resin with good compatibility can be provided.

Claims

1. The hollow silica particles have a space inside the shell, and the hollow silica particles contain aluminum atoms that form aluminosilicate sites. When measured by a dissolution method using an aqueous hydrofluoric acid solution, the aluminum atoms present throughout the hollow silica particles are found to be 100% or less. ２ O ３ Converted to SiO ２ 120 to 50,000 ppm / SiO per 1 g ２ The hollow silica particles are bonded at a ratio (B).

2. 2. The hollow silica particles according to claim 1, wherein the ratio of [specific surface area (C) of the hollow silica particles measured by the BET method (nitrogen gas adsorption method)] / [specific surface area (D) of the hollow silica particles measured by a transmission electron microscope] is 1.40 to 5.

00.

3. Hollow silica particles SiO ２ 2. The hollow silica particles according to claim 1, wherein the surface charge amount calculated per 1 g is 5 to 250 μeq / g.

4. The hollow silica particles may further comprise a compound represented by formula (1), formula (2), or formula (3): 【Chemistry 1】 (In formula (1), R １ each 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, or a cyano group, and is bonded to a silicon atom by a Si-C bond; R ２ each represents an alkoxy group, an acyloxy group, or a halogen atom; a represents an integer of 1 to 3; In formula (2) and formula (3), R ３ and R ５ are each an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 30 carbon atoms and bonded to a silicon atom by a Si—C bond; R ４ and R ６ each represents an alkoxy group, an acyloxy group, or a halogen atom, Y represents an alkylene group, an NH group, or an oxygen atom, b is an integer of 1 to 3, c is an integer of 0 or 1, and d is an integer of 1 to 3.

5. 5. A hollow silica sol comprising the hollow silica particles according to claim 1 dispersed in a dispersion medium, the hollow silica particles having an average particle size of 20 to 150 nm as measured by a dynamic light scattering method.

6. 6. The hollow silica sol according to claim 5, wherein the dispersion medium is an alcohol having 1 to 10 carbon atoms, a ketone having 1 to 10 carbon atoms, an ether having 1 to 10 carbon atoms, or an ester having 1 to 10 carbon atoms.

7. The hollow silica sol according to claim 5 , further comprising an amine.

8. The hollow silica sol according to claim 7, wherein the amine is at least one amine selected from the group consisting of primary amines having 1 to 10 carbon atoms, secondary amines having 1 to 10 carbon atoms, and tertiary amines having 1 to 10 carbon atoms.

9. The hollow silica sol according to claim 7, wherein the amine is a water-soluble amine having a water solubility of 80 g / L or more.

10. The content of the amine is SiO of the hollow silica particles. ２ The hollow silica sol according to claim 7, wherein the content is 0.001 to 10% by mass based on the total mass of the hollow silica sol.

11. A film-forming composition comprising the hollow silica particles according to any one of claims 1 to 4 and an organic resin.

12. A film-forming composition comprising hollow silica particles derived from the hollow silica sol according to claim 5 and an organic resin.

13. A film obtained from the film-forming composition according to claim 11, which has a visible light transmittance of 80% or more.

14. A film having a visible light transmittance of 80% or more, obtained from the film-forming composition according to claim 12.

15. The following steps (I) and (II): Step (I): preparing a hollow silica aqueous sol; Step (II): Add an aluminum compound to the hollow silica aqueous sol obtained in step (I) in an amount of Al per 1 g of hollow silica particles. ２ O ３ and heating at 40 to 260° C. for 0.1 to 48 hours. The method for producing the hollow silica sol according to claim 5, comprising:

16. 16. The method for producing a hollow silica sol according to claim 15, wherein the hollow silica aqueous sol used in the step (I) is one which has been subjected to a step of heating in an aqueous medium at a heating temperature of less than 100°C.

17. 16. The method for producing a hollow silica sol according to claim 15, wherein the hollow silica aqueous sol used in the step (I) is one which has been subjected to a step of heating in an aqueous medium at a heating temperature of 100°C to 240°C.

18. The method for producing hollow silica sol according to claim 15, wherein the aluminum compound used in the step (II) is at least one aluminum compound selected from the group consisting of an aluminate, an aluminum alkoxide, and a hydrolyzate thereof, and the step (II) uses an aqueous solution containing the aluminum compound.

19. The method for producing a hollow silica sol according to claim 15, wherein the step (II) further comprises a step (II-i) of adding an amine.

20. In the step (II), a neutral salt consisting of a combination of at least one cation selected from the group consisting of sodium ions, potassium ions, and ammonium ions and an inorganic anion or an organic anion is added to the SiO ２ The method for producing a hollow silica sol according to claim 15, comprising the step (II-ii) of adding the above-mentioned compound in an amount of 0.1 to 10 mass % based on the total mass of the compound.

21. The inorganic anion used in step (II-ii) is a sulfate ion, a chloride ion, or a phosphate ion.

21. The method for producing a hollow silica sol according to claim 20, wherein the organic anion is a carboxylate ion, an oxycarboxylate ion, or an amino acid.

22. The method for producing hollow silica sol according to claim 15, wherein the step (II) comprises a step of adding the aluminum compound, or the aluminum compound and at least one additive selected from the group consisting of amines and neutral salts, to a hollow silica aqueous sol and heating the mixture, and then a step (II-iii) of contacting the mixture with a cation exchange resin, a step (II-iv) of adding an acid, or a combination thereof.

23. 16. The method for producing hollow silica sol according to claim 15, further comprising a step (III) of solvent-substituting the aqueous medium in the hollow silica sol with an alcohol having 1 to 10 carbon atoms, a ketone having 1 to 10 carbon atoms, an ether having 1 to 10 carbon atoms, or an ester having 1 to 10 carbon atoms after completion of the step (II).

24. The method for producing hollow silica sol according to claim 23, further comprising a step (IV) of adding at least one silane compound selected from the group consisting of formula (1), formula (2), and formula (3) defined in claim 4, and heating after the completion of the step (III).

25. The method for producing hollow silica sol according to claim 24, wherein the steps (III) and (IV) are steps of, after completion of the step (II), replacing the aqueous medium of the hollow silica sol with an alcohol having 1 to 10 carbon atoms in the step (III), adding at least one silane compound selected from the group consisting of the formulas (1), (2), and (3) in the step (IV), heating, and then replacing the alcohol solvent with a ketone having 1 to 10 carbon atoms, an ether having 1 to 10 carbon atoms, or an ester having 1 to 10 carbon atoms.

26. A method for adjusting the surface charge of hollow silica particles, which comprises using the method for producing hollow silica sol according to claim 15.

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