JP2019116396A - Silica-based particle dispersion and production method thereof - Google Patents

Abstract

To provide a silica-based particle-containing dispersion and a production method thereof.SOLUTION: To a dispersion containing uniform silica particles with an average particle diameter of 3 to 10 nm, a hydrolyzable metal compound is added for hydrolysis in the presence of an alkali catalyst in order to grow the silica particles so that a uniform silica-based particle dispersion with an average particle diameter of more than 10 nm and 300 nm or less is produced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a silica-based particle dispersion using silica fine particles having an average particle size of 3 to 10 nm.

  For example, high purity silica sol is a polishing agent for silicon wafer, raw material such as high purity silica gel for liquid chromatography carrier, binder for catalyst, raw material of special zeolite, micro filler added to paint for electronic material, micro for polymer film It is used in the field of fillers and the like.

  Such high purity silica sol is generally prepared by mixing silane alkoxides such as tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS) with water and an alkali catalyst such as ammonia, an amine compound, etc. to cause hydrolysis and condensation. It manufactures by making it polymerize (for example, refer patent document 1).

  On the other hand, silica sol (small particle diameter silica sol) containing silica particles of small particle diameter is especially used for final polishing of a 300 mm wafer, can improve flatness without scratching, and adhere to the substrate. The removal effect of The small particle size silica sol can also be used as a polishing agent in chemical mechanical polishing at the time of large scale integrated circuit production in which remarkable miniaturization has been promoted. In addition, the small particle size silica sol can exhibit high hardness by being added to an optical film or a molded product, and a film with low haze can also be obtained.

JP, 2014-198649, A

  As described above, in the production of high purity silica sol, it was produced from ammonia or an amine compound used alone or as a mixture as a hydrolysis catalyst, and further from the general use of these for the purpose of pH adjustment. When a minute silica sol is used in a high-precision semiconductor wafer in recent years, it is feared that an amine compound or the like is trapped on the interconnect of the wafer, causing contamination of the resist and resulting in production defects. That is, there is a concern that the nitrogen-containing compound contaminates the wafer and the production line, resulting in a decrease in electrical characteristics such as defect generation of a circuit or element formed on the wafer or an abnormality in leak current or a reduction in yield.

  In addition, although the reaction rate of the hydrolyzate is adjusted in order to obtain fine particles in the above-mentioned conventional production method, the unhydrolyzate remains, so the produced particles and their reaction Since microgels are generated, it is difficult to obtain monodispersed particles of 10 nm or less, and there is a problem that it is difficult to prepare reproducible ones. In particular, in order to determine minute particles under an alkaline catalyst, it is important to form minute seeds (seed particles) during hydrolysis, but such seeds have not been obtained. For example, in the method of Patent Document 1, a minute seed can not be obtained because a large amount of alkali is required, and as a result, particles grow to a size exceeding 10 nm.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a dispersion containing highly pure silica particles substantially free of a nitrogen-containing compound and a method for producing the same. Another object of the present invention is to provide a dispersion containing high purity silica fine particles having a small particle size such as 3 to 10 nm in average particle size and a method for producing the same. Further, another object of the present invention is to provide a silica-based particle dispersion liquid using the high-purity silica fine particles having a small particle diameter and a method for producing the same.

  The present inventors are studying the production of high purity silica particles as described above, and using silanes (micro-nano bubbles) having an average bubble diameter of 40 nm to 10 μm without using an alkali catalyst. It has been found that the alkoxide can be hydrolyzed, whereby silica particles can be obtained.

  Although the details of the reason why the silica particles are generated in the coexistence of the microbubbles are unknown, the present inventors found that the concentration of the silane alkoxide occurs at the microbubble interface, the pressure becomes high at the time of the bubble disappearance, and the rupture occurs. It is presumed that water is decomposed by the generated shock wave to generate a hydroxy radical, which promotes the hydrolysis of the silane alkoxide.

  Here, the microbubbles used in the production method of the present invention are microbubbles having an average cell diameter of 40 nm to 10 μm, so-called nanobubbles having a cell diameter of 40 to 100 nm (0.1 μm), and a cell diameter of 0.1. It contains at least one of so-called microbubbles of ̃10 μm, and preferably contains both.

More specifically, we think as follows.
In the liquid layer, the microbubbles have a quasi-equilibrium relationship by the Laplace force represented by Formula (1).

ΔP = 4σ / D (1)
(However, ΔP: pressure difference between bubble internal pressure and solution, σ: surface tension, D: bubble diameter)

  In many cases, the bubbles generated by the bubble generator coexist with nanobubbles and microbubbles. These bubbles are relatively stable if no stimulus is applied, but when a stimulus such as stirring or a change in surface tension of the gas-liquid interface of the bubbles is applied, the Laplace force becomes a driving force and the equilibrium is lost. In particular, since the gas in the bubble is pressurized by the Laplace force, when the stirring or a change in the surface tension of the gas-liquid interface of the bubble occurs, the gas dissolves from the bubble into the liquid phase, according to equation (1) Laplace power increases. As a result, the bubble shrinks, the internal pressure further increases, and eventually it bursts and disappears in water. At this time, energy based on the charge accumulated at the bubble interface is released together with the shock wave generated upon rupture. This causes hydrolysis of water to generate hydroxyl radicals to decompose the silane alkoxide. It is believed that the generated silane alkoxide radical is separated as a solid phase to form particles, thereby producing silica particles.

Here, the generated microbubbles generated by the bubble generator are more unstable than the nanobubbles. In addition, the microbubbles, when some external stimulus is applied, the Laplace force is exerted, the contraction of the bubbles occurs, the time to disappear in water via the size of the nanobubbles is extremely short, and the stability is bad . It is believed that this is because the state of the interface (the charge accumulated at the bubble interface) is different from the nanobubbles (NB) at the time of generation. Energy based on the charge accumulated at the bubble interface is released together with the shock wave generated when the microbubble-derived nanobubble (NB _M ) bursts, which causes hydrolysis of water to generate hydroxyl radicals. It is thought that it decomposes the silane alkoxide.

  As described above, nanobubbles (NB) are more stable than microbubbles, which is believed to be due to the formation of a high negative surface potential on the nanobubble surface. In the production method of the present invention, when the microbubbles and the nanobubbles coexist, the shock wave at the time of the annihilation of the microbubbles triggers a chain reaction of the reduction and annihilation of the nanobubbles and the generation of the shock wave, and the hydroxy radical and the silane alkoxide radical. Is believed to promote the hydrolysis of the silane alkoxide. It is thought that the microbubbles function as a trigger for the hydrolysis reaction because the reduction and annihilation of nanobubbles and the generation of shockwaves are slower than the reduction and annihilation of microbubbles and the generation of shockwaves. In addition, in combination with ultrasound and ultraviolet radiation, stimulation such as ultrasound causes reduction and annihilation of nanobubbles, triggers of shock waves, or ultrasound causes hot spots at the interface of nanobubbles to promote hydrolysis of water. I believe.

Furthermore, the present inventors have found that, by hydrolyzing a silane alkoxide using microbubbles having an average cell diameter of 40 nm to 10 μm, silica fine particles having a small particle diameter such as an average particle diameter of 3 to 10 nm can be produced. . The inventors of the present invention show that, in the alkaline catalysis, the hydrolysis of the alkoxy group bonded to the metal atom occurs rapidly and stepwise, while in the reaction using the micro bubbles as in the present invention, the mechanical shock wave is generated. It is thought that the step hydrolysis reaction can be suppressed because it is applied to all bonds with equal force, and it is thought that this makes it possible to produce silica particles with a small particle size of 10 nm or less. .
Although it is not clear why the microbubbles can stably exist in the liquid, it is not possible for salts, organic substances, inorganic substances, etc. present in the liquid to suppress the dissolution of the microbubbles in the aqueous solution. It is thought that it will be metastable because it does not work and gas dissolution by Henry's law is less likely to occur. However, if there is an environment in which the dissolution of gas is promoted, for example, physical stimulation such as vibration, addition of catalyst such as ammonia, etc., the equilibrium relationship in the liquid is broken, or if there is environmental change due to light, heat, etc. I think that will shrink and disappear.

That is, the present invention relates to a silica particle dispersion liquid containing silica fine particles having an average particle diameter of 3 to 10 nm. The silica particle dispersion preferably satisfies at least one of the following conditions (a) to (c), more preferably two conditions, and still more preferably all three conditions.
(A) The content of Na contained in the silica fine particles is 10 ppm or less.
(B) It includes microbubbles having an average bubble diameter of 40 nm to 10 μm.
(C) The total content as NH _X (X is an integer of 1 to 4) of the compound containing a nitrogen atom contained in the entire dispersion is 1 ppm or less based on silica.

  In addition, in the silica particle dispersion liquid, the content of each of Al, Ca, Mg, Ti, K, Zn, Pb, Cr, Fe, Mn, Ag, Cu, and Ni contained in the whole dispersion liquid relative to silica It is preferably 10 ppm or less.

  Further, the present invention relates to a method for producing a silica particle by hydrolyzing a silane alkoxide in a liquid phase containing microbubbles having an average cell diameter of 40 nm to 10 μm, preferably silica microparticles having an average particle diameter of 3 to 10 nm . The microbubbles are preferably bubbles containing at least one of nitrogen, hydrogen, oxygen, ozone, carbon dioxide gas, and a rare gas.

In this method for producing silica particles, it is preferable to mix a first solution containing a silane alkoxide with a second solution containing microbubbles having an average cell diameter of 40 nm to 10 μm, and the second solution is It is preferable to contain air bubbles at 1.0 × 10 ⁵ cells / mL or more.
Moreover, in this production method, silica particles can be produced without using an alkali catalyst.

Furthermore, the present invention relates to a method for producing silica-based particles in which larger particles are produced using silica fine particles having an average particle diameter of 3 to 10 nm produced by the above-described method for producing silica particles. That is, according to the method for producing silica-based particles of the present invention, silane alkoxide is hydrolyzed in a liquid phase containing microbubbles having an average cell diameter of 40 nm to 10 μm to prepare silica fine particles having an average particle diameter of 3 to 10 nm. A fine particle preparation step, and a particle growth step of adding a hydrolyzable metal compound to the dispersion containing the fine silica particles in the presence of an alkali catalyst to carry out hydrolysis to grow the fine silica particles.
The average particle diameter of the silica-based particles produced in the particle growth step is preferably particles having a diameter of more than 10 nm and 300 nm or less.
Also, the hydrolysis in the particle growth step is preferably performed in the presence of microbubbles having an average cell diameter of 40 nm to 10 μm.

Since the silica particle dispersion liquid of the present invention contains silica particles of high purity, it is added to raw materials such as abrasives for semiconductors, high purity silica gels for liquid chromatography carriers, binders for catalysts, raw materials for special zeolites, paints for electronic materials Can be suitably used as the microfiller, the microfiller for polymer films, etc., and the use of a seed used in the process of producing the same.
In addition, since the method for producing silica particles of the present invention does not use an alkali catalyst as in the prior art, it is possible to produce silica particles with extremely high purity, which is not available in the prior art. In addition, since no alkali catalyst is used, there is no need to perform solvent substitution or the like for removing or reducing alkali, and contamination with new impurities and uniformity caused by particle aggregation are not impaired. The cost is lower.
Further, according to the method for producing silica-based particles of the present invention, particles can be produced with uniform particle size distribution by causing particle growth (build-up) using the silica fine particles produced by the above method for producing silica particles. . In this method, by performing particle growth in the presence of microbubbles, it is possible to suppress the generation of non-reacted substances, microgels, and the like, and to produce silica-based particles having a more uniform particle size distribution.
Furthermore, the remaining microbubbles not involved in the reaction not only suppress the generation and growth of biological organic matter such as microorganisms and algae, but also suppress and generate the generation of microgels in order to generate a shock wave at the time of disappearance. Promote redispersion of the microgels. Therefore, it is considered to be effective for maintaining and improving the filterability.

It is a TEM photograph of the silica particle manufactured by Example 1 (O ₂ micro nano bubble water). It is a TEM photograph of the silica particle manufactured by Example 2 (N ₂ micro nano bubble water).

Silica particle dispersion
The silica particle dispersion liquid of the present invention contains silica fine particles having an average particle diameter of 3 to 10 nm. The silica particle dispersion can be produced by hydrolyzing a silane alkoxide in a liquid phase containing microbubbles having an average cell diameter of 40 nm to 10 μm.

The silica particle dispersion preferably satisfies at least one of the following conditions (a) to (c), more preferably two conditions, and still more preferably all three conditions.
(A) The content of Na contained in the silica fine particles is 10 ppm or less.
(B) It includes microbubbles having an average bubble diameter of 40 nm to 10 μm.
(C) The total content as NH _X (X is an integer of 1 to 4) of the compound containing a nitrogen atom contained in the entire dispersion is 1 ppm or less with respect to silica (fine particles of 3 to 10 nm).

Silica fine particles
As described above, the silica fine particles of the present invention have an average particle diameter of 3 to 10 nm, and the Na content in the silica fine particles is preferably 10 ppm or less, more preferably 5 ppm or less, and 1 ppm or less It is further preferred that Conventionally, when water glass is used as a raw material, silica fine particles having an average particle diameter of 10 nm or less have also been produced, but in the silica fine particles produced using this water glass, Na is contained in excess of 10 ppm. It had been. On the other hand, the silica fine particles of the present invention are produced using a silane alkoxide as a raw material, are substantially free of Na, and can be distinguished from conventional silica fine particles using water glass as a raw material.

  Here, the average particle size of the silica fine particles was determined by TEM observation. Specifically, the dispersion of the present invention is dried and photographed with a transmission electron microscope at a magnification of 250,000. The particle diameter of an arbitrary 500 particles in the obtained photographic projection was measured, and the average value was taken as the average particle diameter of the silica fine particles.

  Further, the amount of Na contained in the silica fine particles is a value obtained by analyzing the silica particle dispersion (A) obtained by ion-exchanging the prepared silica particle dispersion with a cation exchange resin by ICP mass spectrometry. It is.

Furthermore, the silica fine particles preferably have a specific surface area of 270 to 900 m ² / g, and more preferably 400 to 700 m ² / g. When the specific surface area of the silica fine particles is less than 270 m ² / g, monodispersed particles are difficult to obtain. Therefore, there is a problem that the viscosity of the dispersion increases. On the other hand, when it exceeds 900 m ² / g, the silica fine particles are easily dissolved or aggregated. Therefore, there is a problem that monodispersed particles are difficult to obtain.

  Here, the specific surface area of the silica fine particles is a value obtained by the BET method after drying the dispersion liquid of the present invention.

  The surface charge of the silica fine particles is preferably 260 to 900 μeq / g, and more preferably 350 to 750 μeq / g. If the surface charge amount of the high purity silica fine particles is less than 260 μeq / g, the hydrolysis is insufficient, so the negative charge of the silica particles is small and there is a problem that aggregation tends to occur, and when it exceeds 900 μeq / g There is a problem that the stability of the silica particles is easily impaired.

  The surface charge amount of the silica fine particles is determined by dropping a cationic polymer of known concentration (0.0025 N diallyldimethyl ammonium chloride solution made by WAKO) into a dispersion using a flow potential meter (PCD-500 manufactured by Kyoto Denshi Kogyo Co., Ltd.). It is a value determined from the consumption of the polymer to be neutralized.

<Micro bubbles (micro nano bubbles)>
It is preferable that the silica particle dispersion liquid of this invention contains the micro bubble of 40 nm-10 micrometers of average bubble diameters. Such microbubbles contain at least one of so-called nanobubbles having a bubble diameter of 40 to 100 nm (0.1 μm) and so-called microbubbles having a bubble diameter of 0.1 to 10 μm, and those containing both are preferable . The upper limit of the average cell diameter of the microbubbles is preferably 500 nm, more preferably 350 nm, and still more preferably 200 nm. The lower limit of the average cell diameter of the micro-nano bubbles is preferably 50 nm, more preferably 60 nm, and still more preferably 65 nm.

That is, in the silica particle dispersion, microbubbles not used for the reaction usually remain. This microbubble content in the silica particle dispersion is not particularly limited, the lower limit is preferably 1.0 × 10 ³ cells / mL, more preferably 1.0 × 10 ⁵ cells / mL And 1.0 × 10 ⁸ cells / mL are more preferable. The upper limit thereof is preferably 1.0 × 10 ¹¹ cells / mL, more preferably 5.0 × 10 ¹⁰ cells / mL, and still more preferably 1.0 × 10 ¹⁰ cells / mL.

  The average bubble diameter and the number of bubbles of the microbubbles can be determined by analyzing the Brownian movement movement velocity of the bubbles in the liquid by nanoparticle tracking analysis (NTA). For example, “Nanosite NS300” manufactured by Malvern, It can be used to measure.

  In the present state of the art, it is difficult to measure the average cell diameter and the number of cells of the microbubbles as it is in the dispersion liquid in which the silica particles and the microbubbles coexist, so the silica particles should be an ultrafiltration membrane. The average cell size and number of cells of the microbubbles are measured by removing only the microbubbles and measuring this. That is, the average cell diameter and the number of cells of the present invention refer to those obtained by measuring the filtrate which has passed through the ultrafiltration membrane with a molecular weight cut off of 6000.

  The gas for forming the microbubbles is preferably at least one of nitrogen, hydrogen, oxygen, ozone, carbon dioxide gas, and a rare gas. These gases have the effect of destroying biological cells by the shock wave upon extinction, and are effective for both biological contamination and long-term storage.

Silica particle dispersion
In the silica particle dispersion liquid of the present invention, the total content of the compound containing a nitrogen atom as NH _X (X is an integer of 1 to 4) is preferably 1 ppm or less based on silica, and is preferably 0.5 ppm or less It is more preferable that the concentration be 0.1 ppm or less. That is, since this silica particle dispersion can be manufactured without using an alkali catalyst consisting of a compound containing a nitrogen atom such as ammonia or an amine compound, it does not substantially contain a nitrogen source.

The total content of NH _X of the compound containing a nitrogen atom refers to the total content based on the following ammonia analysis method and amines analysis method.
(1) Ammonia analysis method Measure by Kjeldahl method. Specifically, the sample is thermally decomposed using sulfuric acid or the like, the nitrogen in the sample is made ammonium sulfate, then the decomposition solution is made alkaline, liberated ammonia is distilled, and the amount of ammonia is measured by titration.
(2) Amines analysis method It measures by ion chromatography. Specifically, the content is determined from the calibration curve and quantified by directly introducing the sample into an ion chromatograph (apparatus model: ICS-1000).

When the total content of the compound containing nitrogen atoms as NH _x (where X is an integer of 1 to 4) exceeds 1 ppm with respect to silica, for example, fine wiring nodes formed on a semiconductor wafer are 32 nm or less When used for wiring formation, it is feared that amine compounds and the like will be trapped on the wafer interconnections, causing contamination of the resist and resulting in production defects. That is, there is a concern that the nitrogen-containing compound contaminates the wafer and the production line, resulting in a decrease in electrical characteristics such as defect generation of a circuit or element formed on the wafer or an abnormality in leak current or a reduction in yield. In addition, the hydrolysis of the unhydrolyzate proceeds with time, which may change the stability of the dispersion.

In the silica particle dispersion liquid of the present invention, the content of each of Al, Ca, Mg, Ti, K, Zn, Pb, Cr, Fe, Mn, Ag, Cu, and Ni with respect to silica is 10 ppm or less It is preferably 1 ppm or less, more preferably 0.5 ppm or less.
When the content of each of Al, Ca, Mg, Ti, K, Zn, Pb, Cr, Fe, Mn, Ag, Cu and Ni exceeds 10 ppm with respect to silica, the surface potential of the particles is lowered, There is a problem that the stability is impaired, and changes in the insulating properties and electrical characteristics of the coating film are likely to occur.

  Each content of Al, Ca, Mg, Ti, K, Zn, Pb, Cr, Fe, Mn, Ag, Cu, and Ni in the silica particle dispersion is a value determined by ICP mass spectrometry.

<< Production method of silica particle dispersion liquid (seed) >>
The method for producing a silica particle dispersion liquid of the present invention is characterized in that a silane alkoxide is hydrolyzed in a liquid phase containing microbubbles having an average cell diameter of 40 nm to 10 μm to produce a silica particle dispersion liquid. The specific method is not particularly limited as long as it is a method of producing a silica particle dispersion by hydrolysis of For example, a method (mixture method) of promoting hydrolysis of a silane alkoxide by mixing a first solution containing a silane alkoxide as a raw material and a second solution containing microbubbles having an average cell diameter of 40 nm to 10 μm The method (generation method) etc. which generate | occur | produce a micro bubble in the liquid phase in which a silane alkoxide exists, and advance a hydrolysis of a silane alkoxide can be mentioned. In the mixing method, various methods can be adopted such as a method of adding one solution to the other solution at once, a method of dropping the other solution to one solution, a method of dropping both solutions to the filling solution, and the like.

  As a silica particle manufactured by this manufacturing method, although it is preferable that it is a silica particle with an average particle diameter of 3-10 nm, it is not limited to this. For example, larger particles can be produced using such silica fine particles having an average particle diameter of 3 to 10 nm as a seed. Under the present circumstances, although it does not prevent using the alkali catalyst which consists of nitrogen containing compounds, such as ammonia and an amine compound, using the alkali catalyst which consists of phosphorus containing compounds so that the dispersion liquid and particle containing nitrogen containing compounds may not be produced. Is preferred. As an alkali catalyst consisting of a phosphorus containing compound, phosphonium hydroxide is preferable and tetrabutyl phosphonium hydroxide is especially preferable.

<Silane alkoxide>
In the method of producing silica particles, a silane alkoxide represented by the following formula (2) is suitably used.
X _n Si (OR) _4-n (2)
In the formula, X represents a hydrogen atom, a fluorine atom, an alkyl group having 1 to 8 carbon atoms, an aryl group or a vinyl group, R represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group or a vinyl group, n is an integer of 0 to 3;
In particular, tetramethylalkoxysilane, tetraethylalkoxysilane and the like can be suitably used. Moreover, you may use 2 or more types of silane alkoxides.

  As a solvent for dispersing and dissolving the silane alkoxide (in the case of the mixing method, the solvent of the first solution), for example, an alcohol such as methanol, ethanol, propanol or butanol, acetone, toluene, xylene, tetrahydroxyfuran or the like is used. Can.

<Micro bubbles (micro nano bubbles)>
The microbubbles used in this production method are microbubbles having an average cell diameter of 40 nm to 10 μm, so-called nanobubbles having a cell diameter of 40 to 100 nm (0.1 μm), and so-called microbubbles having a cell diameter of 0.1 to 10 μm. It is preferable to include at least one of the bubbles, and to include both of the bubbles. The upper limit of the average cell diameter of the microbubbles is preferably 500 nm, more preferably 350 nm, and still more preferably 200 nm. Moreover, 50 nm is preferable, as for the minimum of the average bubble diameter of a micro nano bubble, it is more preferable that it is 60 nm, and it is more preferable that it is 65 nm.

  Here, when the average bubble diameter of the microbubbles exceeds 10 μm, the surface tension of the particles in the aqueous solution is small, and the coalescence of the bubbles is likely to occur, which is not preferable. It is unsuitable for raising it. When the average bubble diameter of the microbubbles is less than 40 nm, the surface tension is large, the internal pressure of the bubbles is increased and the bubbles are easily ruptured, and the stabilization period is short. That is, the size of the air bubble has an optimum range, and any air bubble may not be used.

The amount of microbubbles relative to the silane alkoxide can be appropriately set within a range in which the hydrolysis of the silane alkoxide proceeds sufficiently. For example, in the mixing method, a second solution having a microbubble content of preferably 1.0 × 10 ⁵ cells / mL or more, more preferably 1.0 × 10 ⁸ cells / mL or more is introduced into the first solution Do. The upper limit of the microbubble content in the second solution is preferably 1.0 × 10 ¹¹ cells / mL, more preferably 5.0 × 10 ¹⁰ cells / mL, and 1.0 × 10 ¹⁰ cells / mL. More preferable.
Here, if the content of the microbubbles of the second solution is less than 1.0 × 10 ⁵ pieces / mL, there is a risk that the hydrolysis of the silane alkoxide for producing the silica particles may be insufficient. When it exceeds 0 × 10 ¹¹ cells / mL, the reaction rate is fast and reproducibility is difficult to obtain.

  Moreover, it is preferable to add 0.5 mol times-10 mol times the 2nd solution containing the micro bubble of the above quantity with respect to the number-of-moles of the functional group (OR) of a silane alkoxide. Here, if the second solution is used more than 10 molar times, there is a problem that water remaining when evaporating the composition or during heat treatment causes a crack, and in the case of less than 0.5 molar times, Insufficient hydrolysis may cause the reaction to stop prematurely.

  The gas used for the microbubbles preferably includes at least one of nitrogen, hydrogen, oxygen, ozone, carbon dioxide gas, and a rare gas. These gases can generate hydroxyl radicals, and at the same time, they can exert an effect of disintegrating the microgel by the rupture of the microbubbles, and also, biological cells can be produced by the shock wave when the microbubbles disappear as a secondary effect. It has a destructive effect and is effective for biological contamination and long-term storage.

  The method of generating the microbubbles (micro-nano bubbles) is not particularly limited, and conventionally known methods can be used. For example, various systems such as a swirl flow system, a static mixer system, an ejector system, a venturi system, a pressure dissolution system, a pore system, a rotary system, an ultrasonic system, a vapor condensation system, and an electrolysis system can be mentioned. In addition, it is possible to increase or refine the concentration of micro-nano bubbles by repeatedly passing the solution.

  The hydrolysis reaction of the silane alkoxide can usually be performed at 5 to 95 ° C. under normal pressure, and is preferably performed at a temperature lower than the boiling point of the solvent. In the case of the mixing method, it is preferable to carry out at a temperature lower than the lower one of the boiling point of the first solution and the boiling point of the second solution. Moreover, you may carry out in a temperature range which does not boil under pressure. Further, the solution containing the silane alkoxide and the microbubbles may be irradiated with ultraviolet light or ultrasonic waves. This accelerates the hydrolysis reaction of the silane alkoxide more quickly, so that the formation of silica particles can be performed in a short time, which is economical.

  Here, in the case of using the mixing method, water is mainly used as a solvent of the second solution, but when an organic solvent compatible with the solvent of the first solution is used together with water, the concentration of microbubbles is used. Is preferable because it can increase the As such an organic solvent, for example, dimethyl sulfoxide (DMSO), acetic acid (AcOH), N, N-dimethylformamide (DMF), methanol (MeOH), ethyl acetate (AcOEt), acetone and the like are preferable, and the viscosity and dielectric constant The higher the amount, the more total microbubbles tend to be.

  Here, if ultrafiltered water containing microbubbles generated by ultrafiltration is used when generating microbubbles, it becomes a resource saving process, and contamination of impurities such as metal can be reduced. When this ultrafiltrate is used as the second solution, since the microbubbles are fractionated by the ultrafiltration membrane, the life of the microbubbles is long and there is an advantage that high concentration microbubbles can be used. preferable.

<< Production Method of Silica-Based Particle Dispersion >>
The method for producing the silica-based particle dispersion liquid (preferably, the average particle diameter of the silica-based particles is more than 10 nm and 300 nm or less) of the present invention is the silica fine particles produced by the above-mentioned production method of the present invention using The particles are grown (build up) by hydrolysis in the presence of alkali as a seed (seed particle) having a particle diameter of 3 to 10 nm. For this reason, it is preferable to use the seed dispersion liquid substituted with a water solvent.
That is, in the method for producing a silica-based particle dispersion, a silane alkoxide is hydrolyzed in a liquid phase containing microbubbles having an average cell diameter of 40 nm to 10 μm to prepare silica fine particles having an average particle diameter of 3 to 10 nm. A fine particle preparation step, and a particle growth step of adding a hydrolyzable metal compound to the dispersion containing the fine silica particles in the presence of an alkali catalyst to cause hydrolysis and growing the fine silica particles. Here, as the hydrolyzable metal in the invention of the present invention, it is also possible to use a hydrolyzable metal compound partially hydrolyzed.
The operation in the fine particle preparation step is the same as the operation described in the above section "<Method for producing silica particles>".

  According to this manufacturing method, particles can be grown in multiple stages (multiple times) using small particles as seeds (seed particles), so that particles with a uniform particle size distribution can be produced. In particular, even in the case of producing relatively small particles, particles having uniform particle size distribution can be produced because multistep growth can be performed from minute seeds.

  In the method of producing the silica-based particle dispersion, in order to stabilize the seed (seed particle) in the particle growth step, the organic solvent is removed and the seed dispersion dispersed in water is aged at a predetermined pH. It is preferable to homogenize the particles involved in the dissolution of the particles in the dispersion, to homogenize the solubility of silica in the dispersion, and the like. In the present specification, this stabilizing operation is referred to as seeding. The pH in seeding is not particularly limited as long as it is in the neutral to alkaline region, but pH 7 or more is preferable, and pH 7 to 10.5 is more preferable. The ripening temperature of the dispersion at this time is not particularly limited as long as the seeds are stabilized, and under normal pressure, the temperature is preferably from room temperature to less than 100 ° C. Further, in order to stabilize the seed, it is preferable to age for about 5 minutes or more. The stabilization of the seed by this seeding can be preferably applied to both the case where the above-mentioned 3 to 10 nm silica fine particle is used as a seed and the case where a particle larger than 10 nm is used as a seed. For example, by performing aging such as heating in the presence of an alkali catalyst, it is possible to achieve uniformity of particles accompanying dissolution of particles in the dispersion, uniformity of silica solubility in the dispersion, and the like. This step is a step preferably carried out to produce uniform particles by causing subsequent particle growth, or even particle growth in multiple steps.

  In the particle growth step, the reaction temperature, pH, seed amount, type and addition amount of hydrolyzable silicon compound, addition rate, and the like are appropriately controlled. In the present invention, for example, when using a hydrolyzable silicon compound, when the concentration of the seed solution used is too high, or when the pH of the seed solution is in the acidic region, the silica particles are unstable and the solubility of the silica is Since the added hydrolyzable silicon compound precipitates as low molecular weight silica and byproducts such as new core particles and monomers and oligomers are generated, seed growth is inhibited and uniform particle growth is suppressed. It can be difficult. For this reason, the seed solution is preferably an aqueous solution in the neutral to alkaline region adjusted to an appropriate concentration.

  In addition, in the case of growing seeds by continuously adding hydrolyzable silicon compounds in the particle growth step, the silicon compound to be added is excessive to the seed amount and the degree of supersaturation becomes abnormally high, or the addition speed is increased. If it is too early, it precipitates as low molecular weight silica, and byproducts such as new core particles and monomers and oligomers are generated, so that not only the growth of seeds is inhibited but also the particle size distribution of the obtained particles becomes broad. There is a fear. For this reason, it is preferable to adjust the addition amount, the addition speed, and the like of the hydrolyzable silicon compound to be added in particle growth in accordance with the seed amount.

In the particle growth process, in order to prevent such nonuniform particle growth due to nucleation and generation of byproducts and to obtain particles with a more uniform particle size distribution, a dispersion liquid of particles grown to some extent in the process of particle growth. From these, it is preferable to remove such a by-product, an organic solvent which is a by-product derived from hydrolysis of an alkoxy group, and unnecessary alkali, and repeat the particle growth as purified seed particles as new seed particles. The particle growth per one time of the multi-step particle growth is preferably within 3 times the average particle diameter of the reference seed particles as a standard.
Here, in the case where the hydrolyzable metal compound is continuously added without adding the hydrolysable metal compound in multiple stages in order to grow the particles to the desired particle size, it takes too long to take time for the particle growth, so that practical use Poor sex. Further, when a large amount of hydrolyzable metal compound is added in a short time, as described above, byproducts such as new core particles and monomers and oligomers may be generated, and the particle size distribution of the obtained particles may also be broadened. There is.

  That is, it is preferable to go through, for example, about 2 to 5 particle growth steps to obtain particles of a target size. Even when relatively small particles having an average particle diameter of more than 10 nm and 300 nm or less, preferably more than 10 nm and about 100 nm are produced by using fine particles as seeds, the desired number of particle growth steps are taken. It is possible to produce particles with uniform particle size distribution.

The hydrolysis in the particle growth step is preferably performed in the presence of microbubbles having an average cell diameter of 40 nm to 10 μm. By hydrolyzing in the presence of microbubbles, a hydrolyzable metal compound (unreacted raw material) whose reaction has not progressed to the target particles due to the dispersing effect by the microbubbles, the crushing effect, the hydrolysis promoting effect, etc. And the generation of low-molecular hydrolyzates thereof and the like and the generation of microgels and the like generated by reacting these with silica-based particles, thereby producing particles with a more uniform particle size distribution. it can.
Furthermore, the remaining microbubbles not involved in the reaction not only suppress the generation and growth of biological organic matter such as microorganisms and algae, but also suppress and generate the generation of microgels in order to generate a shock wave at the time of disappearance. Promote redispersion of the microgels. Therefore, it is considered to be effective for maintaining and improving the filterability.

  Here, the microbubbles are the same as those described above in the section "<Method of producing silica particles>" and thus the description thereof is omitted.

  The hydrolyzable metal compound used in the particle growth step contains a metal such as silicon, titanium, zirconia, aluminum, tin, indium and the like, a compound having a hydrolysable group such as an alkoxy group and a halogen group, and the above metal Chelate compounds and peroxo compounds containing the above metals can be mentioned. In the particle growth step of the present invention, it is preferable to use a hydrolyzable metal compound containing at least silicon, and it can be used alone or with a hydrolysable compound containing other metals. . In addition, as a hydrolysable compound, the hydrolyzate which has a hydroxyl group in the molecule | numerator which partial hydrolysis advanced can also be used as mentioned above.

Specifically, as the hydrolyzable compound containing silicon, at least one of silane alkoxide and silicic acid can be used.
As a silane alkoxide, the silane alkoxide shown by the said General formula (2) can use it preferably. Among them, tetramethylalkoxysilane and tetraethylalkoxysilane are more preferable, and tetramethylalkoxysilane is particularly preferable.
Moreover, as a silicic acid, what was prepared from the alkali metal silicate can be used. For example, a dilute solution of sodium silicate (water glass) can be ion-exchanged with a cation exchange resin or the like to obtain a solution containing silica, which can be used. When a solution containing silica is required to have a high purity silica-based particle dispersion, separation of high molecular weight substances by ultrafiltration membrane, chelating resin, amphoteric ion exchange resin, cation exchange resin, etc. It is preferable to carry out the treatment according to

  Further, as hydrolysable compounds containing titanium, tetramethoxytitanium, tetraisoproxioxytitanium, tetranormalbutyltitanium, butyltitanate dimer, tetraoctyltitanium titanium tetrachloride, titanium acetylacetonate, titanium tetraacetylacetonate, titanium lactate Ammonium salts, titanium triethanolaminate, peroxotitanic acid and the like can be exemplified.

  Examples of hydrolyzable compounds containing zirconia include tetramethoxyzirconium, tetraethoxyzirconium, tetraisoproxyzirconium, normal propyl zirconate, normal butyl zirconate, zirconium chloride, zirconium oxychloride, and zirconium dibutoxy bis (ethylacetoacetonate). , Zirconium tetraacetylacetonate, peroxo zirconate and the like can be exemplified.

  As a hydrolysable compound containing aluminum, trimethoxyaluminum, triethoxyaluminum, triisoproxyaluminum, aluminum secondary butoxide, aluminum chloride, aluminum acetate, aluminum trisacetylacetonate, aluminum bisethylacetoacetate monoacetylacetonate, aluminum It is possible to illustrate tris ethyl acetoacetate and the like.

  Examples of hydrolyzable compounds containing tin include tetraisoproxytin, tetranormal butoxytin, tin (IV) chloride, tin octylate and the like.

  Examples of hydrolyzable compounds containing indium include trimethoxyindium, triethoxyindium, triisoproxyindium, indium chloride, indium triacetylacetonate and the like.

  The reaction in the particle growth step is preferably carried out in the presence of an aqueous solvent containing microbubbles having an average cell diameter of 40 nm to 10 μm and an alkali catalyst. Thus, the solvent of the seed solution is preferably replaced by water. Here, when a hydrolyzable silicon compound or a hydrolyzable metal compound (a metal compound other than silicon) having a high hydrolysis rate and which easily precipitates is added to a solution containing silica fine particles, water and an alkali catalyst, It is preferable to use an organic solvent or a mixed solvent of water and an organic solvent as the solvent of the hydrolyzable metal compound of the above. When the reaction is carried out under normal pressure, it is preferable to carry out using a reflux condenser so that the solvent does not evaporate. Furthermore, when it carries out at the temperature more than a solvent boiling point (in the case of water, 100 degreeC or more), heat-resistant pressure-resistant containers, such as an autoclave, can also be used. In addition, it is preferable that the organic solvent etc. byproduced by hydrolysis contained in the silica type particle dispersion liquid manufactured are substituted by water.

  Examples of the organic solvent include alcohols, ketones, ethers, esters and the like. More specifically, alcohols such as methanol, ethanol and propanol, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and esters such as methyl acetate, ethyl acetate, methyl lactate and ethyl lactate are used. Among these, methanol or ethanol is more preferable, and methanol is particularly preferable. These organic solvents may be used alone or in combination of two or more.

  Examples of alkali catalysts include ammonia, amines, alkali metal hydrides, alkaline earth metal hydrides, alkali metal hydroxides, alkaline earth metal hydroxides, quaternary ammonium compounds, amine coupling agents, etc. The compound which shows is used.

<< Silica-based particle dispersion liquid >>
The silica-based particle dispersion liquid of the present invention is characterized by including silica-based particles having an average particle diameter of more than 10 nm and 300 nm or less and microbubbles having an average bubble diameter of 40 nm to 10 μm. The silica-based particle dispersion can be obtained by the method for producing a silica-based dispersion of the present invention. The microbubbles are the same as those described in the above section "<< silica particle dispersion liquid>".

Silica-based particles
The silica-based particles of the present invention are particles containing only silica (silicon) as a main component, or two or more types containing silicon and at least one element selected from titanium, zirconia, aluminum, tin and indium. The particles are mainly composed of metal oxides of Specifically, as particles mainly composed of two or more types of metal oxides, silicon and at least one metal selected from titanium, zirconia, aluminum, tin, and indium on the surface of core particles composed of silica fine particles The aspect by which the composite metal oxide layer (shell layer) containing is formed can be mentioned.
Here, the main component is 60% by mass or more, preferably 95% by mass or more, more preferably 98% by mass or more, still more preferably 99.5% by mass, based on the oxide, based on the whole substance constituting the particles. The above, most preferably 100% by mass.

As described above, the silica-based particles have an average particle diameter of more than 10 nm and 300 nm or less, preferably more than 10 nm and 200 nm, and more preferably more than 10 nm and 100 nm.
The method of measuring the average particle diameter is the same as the method of measuring the average particle diameter of the above-mentioned silica fine particles (TEM observation method).

The silica-based particles have, for example, a coefficient of variation (CV value) of 0.3 or less, preferably 0.25 or less, more preferably 0.20 or less, and 0.15 or less It is further preferred that
The coefficient of variation (= standard deviation / average particle size) is calculated based on the average particle size obtained by the method of measuring the average particle size of the above-mentioned silica fine particles (TEM observation method).

Furthermore, since the silica-based particles are densified by hydrolysis, the specific surface area is preferably 9 m ² / g or more and less than 270 m ² / g, and 27 m ² / g or more and less than 270 m ² / g It is more preferable that
When the specific surface area of the silica-based particles is less than 9 m ² / g, the particles themselves are likely to be largely sedimented. On the other hand, if the particle size is 270 m ² / g or more, the particles are small, and when a large amount of salt is present in the reaction system, there is a problem that the stability of the silica-based particles is low and gelation easily occurs.
The measuring method of a specific surface area is the same as the measuring method of the specific surface area of the said silica fine particle.

The surface charge amount of the silica-based particles and the above-mentioned silica fine particles is preferably 14 to 900 μeq / g.
The amount of surface charge changes mainly by (1) the surface area of the particles and (2) the hydrolyzability on the particle surface (the reaction of the alkoxy groups being hydrolyzed to form hydroxyl groups). In any case, the amount of surface charge per particle solid content (g) changes greatly depending on the amount of hydroxyl groups involved in the negative charge generation of the particles. In particular, in the case of silica-based particles prepared under high temperature, the effect of (1) is large, and in the above-mentioned silica fine particles (seed) prepared under low temperature, the effect of (2) is large.
Therefore, in the case of silica-based particles having an average particle diameter of more than 10 nm and 300 nm or less, the surface charge amount is preferably 14 to 420 μeq / g, and more preferably 42 to 420 μeq / g. Here, when the surface charge amount of the high purity silica-based particles is less than 14 μeq / g, the particles themselves are likely to be largely sedimented. On the other hand, if it exceeds 420 μeq / g, many relatively small particles are present, so there is a problem that when it is concentrated, its viscosity increases and it tends to gel. At this time, if a large amount of salt is present in the reaction system, the increase in viscosity of the silica-based particle dispersion is accelerated and gelation is more likely to occur.
Further, as described above, in the case of silica fine particles (seed) having an average particle diameter of 3 to 10 nm used to produce the silica-based particles, the surface charge amount is preferably 260 to 900 μeq / g.
The method of measuring the surface charge amount is the same as the method of measuring the surface charge amount of the silica fine particles.

Silica-based particle dispersion
The silica-based particle dispersion liquid of the present invention is required to have high purity, for example, for polishing of semiconductors, and alkali metals, alkaline earth metals, Zn, Pb, Ag, Mn, Co, Mo, Cu, Ni, etc. The content of each of Cr, U and Th is preferably 10 ppm or less, more preferably 1 ppm or less, still more preferably 0.5 ppm or less, with respect to silica.
When the content of each of these metals is more than 10 ppm with respect to silica, the surface potential of the particles is lowered to inhibit the stability, and the insulating property of the coating film, the change of the electrical characteristics and the like are easily caused There's a problem.
The measuring method of metal content is the same as the measuring method of the metal content of the said silica particle dispersion liquid.

Example 1
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. Further, the bubble solution as the second solution is brought into contact with water and O ₂ with a swirl flow type bubble generator (HYK-20-SD manufactured by Ligaric Co., Ltd.) to obtain O ₂ micro-nano bubble water (average bubble diameter: 70 nm, number of bubbles: 240 million cells / mL) was prepared. 25 g of this second solution was added to the first solution, and reacted at 25 ° C. for 5 hours to obtain a silica particle dispersion liquid according to Example 1.
The average particle diameter of the silica particle in the silica particle dispersion liquid which concerns on Example 1 was 5 nm, and as shown in FIG. 1, it was a uniform fine particle. In addition, the silica particle dispersion liquid according to Example 1 in which the silica particles and the microbubbles coexist is filtered through an ultrafiltration membrane (SIP-1013 fraction molecular weight 6000, manufactured by Asahi Kasei Corp.) to remove the silica particles, and the nanobubbles in the filtrate The average cell size and the number of cells were measured to be 75 nm and 150 million cells / mL. Processing conditions etc. and each measurement result are shown in Table 1.

[Average particle size of silica particles]
The average particle size of the silica particles was measured by an image analysis method. Specifically, the silica particle dispersion is dried on a collodion film of a copper cell for an electron microscope with a transmission electron microscope (H-800, manufactured by Hitachi, Ltd.), and photographed at a magnification of 250,000. The particle diameters of arbitrary 500 particles in the obtained photographic projection were measured, and the average value was taken as the average particle diameter of the silica particles.

[Average bubble size and number of bubbles of nano bubble]
The average bubble size and the number of bubbles of the nanobubbles were measured by using the nanoparticle tracking analysis method for the Brownian movement of the bubbles in the liquid. Specifically, while aspirating about 20 mL of a measurement sample (the second solution or the filtrate of the silica particle dispersion according to Example 1), the solution is injected into a measurement device ("Nanosite NS300" manufactured by Malvern), It measured by the tracking analysis method.

[Amount of Na in silica fine particles]
The amount of Na contained in the silica fine particles was measured by ICP mass spectrometry of the silica particle dispersion (A) obtained by ion-exchanging the prepared silica particle dispersion with a cation exchange resin.

[Total content of NH _{X in} the dispersion]
The total content of NH _X of the compound containing a nitrogen atom was measured on the basis of the following ammonia analysis method and amines analysis method, respectively, and the respective measured values were summed to determine.
(1) Ammonia analysis method It measured by the Kjeldahl method. Specifically, the sample was thermally decomposed using sulfuric acid or the like, nitrogen in the sample was changed to ammonium sulfate, then the decomposition solution was made alkaline, liberated ammonia was distilled, and the amount of ammonia was measured by titration.
(2) Amines analysis method It measured by ion chromatography. Specifically, the content was determined from the calibration curve and quantified by directly introducing the sample into an ion chromatograph (model: ICS-1000).

[Content of Al etc. in Dispersion]
The content of each of Al, Ca, Mg, Ti, K, Zn, Pb, Cr, Fe, Mn, Ag, Cu, and Ni in the silica particle dispersion liquid was determined by ICP mass spectrometry.

(Example 2)
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. In addition, the second solution, bubble aqueous solution, is brought into contact with water and N ₂ with a swirl flow type bubble generator (HYK-20-SD manufactured by Ligaric Co., Ltd.), and N ₂ micro-nano bubble water (average bubble diameter: 79 nm, bubble number: 200 million cells / mL) was prepared. 25 g of this second solution was added to the first solution and allowed to react at 25 ° C. for 5 hours to obtain a silica particle dispersion liquid according to Example 2.
The average particle diameter of the silica particle in the silica particle dispersion liquid which concerns on Example 2 was 5 nm, and as shown in FIG. 2, it was a uniform fine particle. In addition, the silica particle dispersion liquid according to Example 2 in which the silica particles and the microbubbles coexist is filtered through an ultrafiltration membrane (SIP-1013 fraction molecular weight 6000, manufactured by Asahi Kasei Co., Ltd.) to remove the silica particles, and the nanobubbles in the filtrate The average cell diameter and the number of cells were measured to be 80 nm and 140 million cells / mL. Processing conditions etc. and each measurement result are shown in Table 1.

(Example 3)
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. Further, the bubble solution as the second solution is brought into contact with water and O ₃ with a swirl flow type bubble generator (HYK-20-SD manufactured by Ligaric Co., Ltd.), and O ₃ micro-nano bubble water (average bubble diameter: 65 nm, number of bubbles: 160 million cells / mL) was prepared. 25 g of this second solution was added to the first solution, and reacted at 25 ° C. for 5 hours to obtain a silica particle dispersion liquid according to Example 3.
The average particle diameter of the silica particles in the silica particle dispersion liquid according to Example 3 was 5 nm. In addition, the silica particle dispersion liquid according to Example 3 in which the silica particles and the microbubbles coexist is filtered through an ultrafiltration membrane (SIP-1013 fraction molecular weight 6000, manufactured by Asahi Kasei Corp.) to remove the silica particles, and the nanobubbles in the filtrate The average cell size and the number of cells were 70 nm and 150 million cells / mL. Processing conditions etc. and each measurement result are shown in Table 1.

(Example 4)
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. Further, the second solution, bubble aqueous solution, is brought into contact with water and a rare gas (Ar) with a swirl flow type bubble generator (HYK-20-SD manufactured by Ligaric Co., Ltd.) to obtain Ar micro-nano bubble water (average bubble The diameter: 75 nm, the number of bubbles: 160 million cells / mL) was prepared. 25 g of this second solution was added to the first solution and reacted at 25 ° C. for 5 hours to obtain a silica particle dispersion liquid according to Example 4.
The average particle diameter of the silica particles in the silica particle dispersion according to Example 4 was 5 nm. In addition, the silica particle dispersion liquid according to Example 4 in which the silica particles and the microbubbles coexist is filtered through an ultrafiltration membrane (SIP-1013 fraction molecular weight 6000, manufactured by Asahi Kasei Corp.) to remove the silica particles, and the nanobubbles in the filtrate The average cell diameter and the number of cells were measured to be 77 nm and 140 million cells / mL. Processing conditions etc. and each measurement result are shown in Table 1.

(Example 5)
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. In addition, the second solution, bubble aqueous solution, is brought into contact with water and N ₂ with a micropore type bubble generator (FN · MP · SO 25 CW-T1 manufactured by Nanox Co., Ltd.) to obtain N ₂ micro-nano bubble water (average Cell diameter: 291 nm, number of cells: 110 million cells / mL) was prepared. 25 g of this second solution was added to the first solution and allowed to react at 25 ° C. for 5 hours to obtain a silica particle dispersion liquid according to Example 5.
The average particle diameter of the silica particles in the silica particle dispersion according to Example 5 was 5 nm. In addition, the silica particle dispersion liquid according to Example 5 in which the silica particles and the microbubbles coexist is filtered through an ultrafiltration membrane (SIP-1013 fraction molecular weight 6000, manufactured by Asahi Kasei Corp.) to remove the silica particles, and the nanobubbles in the filtrate The average cell size and the number of cells were measured to be 294 nm and 100 million cells / mL. Processing conditions etc. and each measurement result are shown in Table 1.

(Example 6)
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. In addition, the second solution, bubble aqueous solution, is brought into contact with water and N ₂ with a swirl flow type bubble generator (HYK-20-SD manufactured by Ligaric Co., Ltd.), and N ₂ micro-nano bubble water (average bubble diameter: 79 nm, number of bubbles: 10 100 cells / mL) was prepared. 25 g of this second solution was added to the first solution and allowed to react at 25 ° C. for 5 hours to obtain a silica particle dispersion liquid according to Example 6.
The average particle diameter of the silica particles in the silica particle dispersion according to Example 6 was 6 nm. In addition, the silica particle dispersion liquid according to Example 6 in which the silica particles and the microbubbles coexist is filtered through an ultrafiltration membrane (SIP-1013 fraction molecular weight 6000, manufactured by Asahi Kasei Corp.) to remove the silica particles, and the nanobubbles in the filtrate The average cell diameter and the number of cells were measured to be 82 nm and 0.080 8 cells / mL. Processing conditions etc. and each measurement result are shown in Table 1.

(Example 7)
While stirring 22 g of denatured ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetramethoxysilane. In addition, the second solution, bubble aqueous solution, is brought into contact with water and N ₂ with a swirl flow type bubble generator (HYK-20-SD manufactured by Ligaric Co., Ltd.), and N ₂ micro-nano bubble water (average bubble diameter: 79 nm, bubble number: 200 million cells / mL) was prepared. 25 g of this second solution was added to the first solution, and reacted at 25 ° C. for 5 hours to obtain a silica particle dispersion liquid according to Example 7.
The average particle diameter of the silica particles in the silica particle dispersion according to Example 7 was 5 nm. In addition, the silica particle dispersion liquid according to Example 7 in which the silica particles and the microbubbles coexist is filtered through an ultrafiltration membrane (SIP-1013 fraction molecular weight 6000, manufactured by Asahi Kasei Corp.) to remove the silica particles, and the nanobubbles in the filtrate Of the average cell diameter and the number of cells were 80 nm and 180 million cells / mL. Processing conditions etc. and each measurement result are shown in Table 1.

(Example 8)
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. In addition, the second solution, bubble aqueous solution, is brought into contact with water and N ₂ with a swirl flow type bubble generator (HYK-20-SD manufactured by Ligaric Co., Ltd.), and N ₂ micro-nano bubble water (average bubble diameter: 79 nm, bubble number: 200 million cells / mL) was prepared. 25 g of this second solution was added to the first solution and reacted at 60 ° C. for 5 hours to obtain a silica particle dispersion liquid according to Example 8.
The average particle diameter of the silica particles in the silica particle dispersion liquid according to Example 8 was 5 nm. In addition, the silica particle dispersion liquid according to Example 8 in which the silica particles and the microbubbles coexist is filtered through an ultrafiltration membrane (SIP-1013 fraction molecular weight 6000, manufactured by Asahi Kasei Corp.) to remove the silica particles, and the nanobubbles in the filtrate The average cell diameter and the number of cells were measured, and it was 81 nm and 170 million cells / mL. Processing conditions etc. and each measurement result are shown in Table 1.

(Example 9)
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. In addition, the second solution, bubble aqueous solution, is brought into contact with water and H ₂ with a swirl flow type bubble generator (HYK-20-SD manufactured by Ligaric Co., Ltd.), and H ₂ micro-nano bubble water (average bubble diameter: 79 nm, bubble number: 200 million cells / mL) was prepared. 25 g of this second solution was added to the first solution, and reacted at 25 ° C. for 5 hours to obtain a silica particle dispersion liquid according to Example 9.
The average particle diameter of the silica particles in the silica particle dispersion liquid according to Example 9 was 5 nm. In addition, the silica particle dispersion liquid according to Example 9 in which the silica particles and the microbubbles coexist is filtered through an ultrafiltration membrane (SIP-1013 fraction molecular weight 6000, manufactured by Asahi Kasei Co., Ltd.) to remove the silica particles, and the nanobubbles in the filtrate The average cell diameter and the number of cells were measured to be 80 nm and 1.9 billion cells / mL. Processing conditions etc. and each measurement result are shown in Table 1.

(Example 10)
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. In addition, the second solution, bubble aqueous solution, is brought into contact with water and N ₂ with a swirl flow type bubble generator (HYK-20-SD manufactured by Ligaric Co., Ltd.), and N ₂ micro-nano bubble water (average bubble diameter: 105 nm, number of bubbles: 8 billion cells / mL) was prepared. 25 g of this second solution was added to the first solution, and reacted at 25 ° C. for 5 hours to obtain a silica particle dispersion liquid according to Example 10.
The average particle diameter of the silica particles in the silica particle dispersion liquid according to Example 10 was 5 nm. In addition, the silica particle dispersion liquid according to Example 10 in which the silica particles and the microbubbles coexist is filtered through an ultrafiltration membrane (SIP-1013 fraction molecular weight 6000, manufactured by Asahi Kasei Corp.) to remove the silica particles, and the nanobubbles in the filtrate The average cell diameter and the number of cells were measured to be 200 nm and 1.9 billion cells / mL. Processing conditions etc. and each measurement result are shown in Table 1.

(Example 11)
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. In addition, the second solution, bubble aqueous solution, is brought into contact with water and N ₂ with a swirl flow type bubble generator (HYK-20-SD manufactured by Ligaric Co., Ltd.), and N ₂ micro-nano bubble water (average bubble diameter: 8000 nm, bubble number: 100 million cells / mL) was prepared. 25 g of this second solution was added to the first solution, and reacted at 25 ° C. for 5 hours to obtain a silica particle dispersion liquid according to Example 11.
The average particle diameter of the silica particles in the silica particle dispersion liquid according to Example 11 was 5 nm. In addition, the silica particle dispersion liquid according to Example 11 in which the silica particles and the microbubbles coexist is filtered through an ultrafiltration membrane (SIP-1013 fraction molecular weight 6000, manufactured by Asahi Kasei Corp.) to remove the silica particles, and the nanobubbles in the filtrate The average cell diameter and the number of cells were measured to be 8100 nm and 0.8 billion cells / mL. Processing conditions etc. and each measurement result are shown in Table 1.

(Comparative example 1)
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. In addition, ion-exchanged water was used as a second solution. 25 g of this second solution was added to the first solution and reacted for 5 hours at 25 ° C., but no particles were formed.

(Comparative example 2)
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. In addition, distilled water was used as a second solution. 25 g of this second solution was added to the first solution and reacted for 5 hours at 25 ° C., but no particles were formed.

(Comparative example 3)
While stirring 22 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 0.49 g of tetraethoxysilane. Further, the bubble solution as the second solution is brought into contact with water and N ₂ with a swirl flow type bubble generator (HYK-20-SD manufactured by Ligaric Co., Ltd.), and N ₂ bubble water (average bubble diameter: 12000 nm) , Number of bubbles: 0.1 billion pieces / mL). 25 g of this second solution was added to the first solution and reacted for 5 hours at 25 ° C., but no particles were formed.

  As shown in Table 1, it was confirmed that silica fine particles of about 5 nm were produced by hydrolyzing a silane alkoxide such as tetramethylalkoxysilane or tetraethylalkoxysilane using microbubbles (micro-nano bubbles). .

(Example 12)
<Fine particle preparation process>
While stirring 814 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 19.4 g of tetraethoxysilane. Further, the bubble solution as the second solution is brought into contact with water and O ₂ with a swirl flow type bubble generator (HVK-20-SD manufactured by Ligaric Co., Ltd.), and O ₂ micro-nano bubble water (average bubble diameter: 121 nm, bubble number: 169 million cells / mL) was prepared. 971 g of this second solution was added to the first solution and allowed to react at 25 ° C. for 5 hours to obtain a silica particle dispersion (liquid A). The O ₂ micro-nano bubble water used in the following examples is the same as the second solution in this example.

  The solution A was concentrated to 375 g using a rotary evaporator (RE device). To this solution was added 450 g of pure water, and the mixture was concentrated by an RE apparatus to obtain 300 g of a concentrated solution. The operation of adding this pure water and concentrating with the RE apparatus was repeated twice to obtain an aqueous dispersion (water solvent replacement step). Thereafter, the pH was adjusted to 9.3 using 3 mass% ammonia water and pure water, to obtain a silica particle dispersion liquid (liquid B) dispersed in water having a silica concentration of 1 mass%. The average particle size of the silica particles in solution B was 5 nm. Details are shown in Table 2 (same below).

Particle Growth Process
100 g of the solution B prepared in the fine particle preparation step was collected and mixed with 200 g of pure water to make a seed solution. On the other hand, the silicic acid solution obtained by cation exchange of No. 3 water glass having a silica concentration of 2.5% by mass is subjected to cation exchange again to form a silicic acid solution having a silica concentration of 2.3% by mass (Additive substance I) Got ready.
As seeding, while stirring the seed solution, it was heated to 80 ° C. and held for 0.5 hours. Subsequently, while the pH of the solution is controlled to be 9.0 by adding a 3% by mass ammonia solution to the seed solution, 1080 g of the above water glass-derived silicic acid (Additive substance I) adjusted to 10 ° C. A silica-based particle dispersion was obtained by adding at a rate of 3.6 g / min. The concentrate was concentrated (deorganic solvent step) with an RE apparatus, and adjusted to pH 9 with 3% by mass ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ . The average particle size of the silica-based particles was 12.5 nm, the standard deviation was 3.1 nm, and the CV value was 0.25. Details are shown in Table 2 (same below).

  In addition, the standard deviation and CV value were computed by the average particle diameter measured according to the measuring method of the silica particle in Example 1 (following same).

(Example 13)
100 g of solution B prepared in the same manner as in Example 12 was collected and mixed with 200 g of pure water to prepare a seed solution. On the other hand, 63 g of tetramethoxysilane was added to 1017 g of O ₂ micro-nano bubble water to prepare a silica solution (additive substance I) having a silica concentration of 2.3 mass%.
As seeding, while stirring the seed solution, it was heated to 80 ° C. and held for 0.5 hours. Subsequently, to the seed solution, a 3% by mass ammonia solution was added to control the pH of the solution to 9.0, and the above tetramethoxysilane-derived silica solution (Additive substance I) adjusted to 10 ° C. 1080 g Was added at a rate of 3.6 g / min to obtain a silica-based particle dispersion. This was concentrated by an RE apparatus, and adjusted to pH 9 with 3 mass% ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ . The average particle size of the silica-based particles was 23.0 nm, the standard deviation was 4.6 nm, and the CV value was 0.20.

(Example 14)
100 g of solution B prepared in the same manner as in Example 12 was collected, and a 25 mass% TMAH solution was mixed with 2.8 g and 197.2 g of pure water to prepare a seed solution. The pH of the solution at this time was 12. On the other hand, 63 g of tetramethoxysilane was added to 1017 g of O ₂ micro-nano bubble water to prepare a silica solution (additive substance I) having a silica concentration of 2.3 mass%.
As seeding, while stirring the seed solution, it was heated to 80 ° C. and held for 0.5 hours. Subsequently, 1080 g of the tetramethoxysilane-derived silica solution (added substance I) adjusted to 10 ° C. was added to the seed solution at a rate of 3.6 g / min to obtain a silica-based particle dispersion. This was concentrated by an RE apparatus, and adjusted to pH 9 with 3 mass% ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ . The average particle size of the silica-based particles was 19.5 nm, the standard deviation was 5.1 nm, and the CV value was 0.26.

(Example 15)
In the fine particle preparation step, 30 g of the silica sol obtained in Example 13 was collected and mixed with 270 g of O ₂ micro-nano bubble water to prepare a seed solution. On the other hand, 63 g of tetramethoxysilane was added to 1017 g of O ₂ micro-nano bubble water to prepare a silica solution (additive substance I) having a silica concentration of 2.3 mass%.
As seeding, while stirring the seed solution, it was heated to 80 ° C. and held for 0.5 hours. Subsequently, to the seed solution, a 3% by mass ammonia solution was added to control the pH of the solution to 9.0, and the above tetramethoxysilane-derived silica solution (Additive substance I) adjusted to 10 ° C. 1080 g Was added at a rate of 3.6 g / min to obtain a silica-based particle dispersion. This was concentrated by an RE apparatus, and adjusted to pH 9 with 3 mass% ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ . The average particle size of the silica-based particles was 46.2 nm, the standard deviation was 6.9 nm, and the CV value was 0.15.

(Example 16)
In the fine particle preparation step, 30 g of the silica-based particle dispersion obtained in Example 15 was collected and mixed with 270 g of O ₂ micro-nano bubble water to prepare a seed solution. On the other hand, 63 g of tetramethoxysilane was added to 1017 g of O ₂ micro-nano bubble water to prepare a silica solution (additive substance I) having a silica concentration of 2.3 mass%.
As seeding, while stirring the seed solution, it was heated to 90 ° C. and held for 0.5 hours. Subsequently, to the seed solution, a 3% by mass ammonia solution was added to control the pH of the solution to 9.0, and the above tetramethoxysilane-derived silica solution (Additive substance I) adjusted to 10 ° C. 1080 g Was added at a rate of 1.8 g / min to obtain a silica-based particle dispersion. This was concentrated by an RE apparatus, and adjusted to pH 9 with 3 mass% ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ . The average particle size of the silica-based particles was 92 nm, the standard deviation was 12.9 nm, and the CV value was 0.14.

(Example 17)
In the fine particle preparation step, 30 g of the silica-based particle dispersion obtained in Example 16 was collected and mixed with 270 g of O ₂ micro-nano bubble water to prepare a seed solution. On the other hand, 63 g of tetramethoxysilane was added to 1017 g of O ₂ micro-nano bubble water to prepare a silica solution (additive substance I) having a silica concentration of 2.3 mass%.
As seeding, while stirring the seed solution, it was heated to 120 ° C. and held for 0.5 hours. Subsequently, to the seed solution, a 3% by mass ammonia solution was added to control the pH of the solution to 9.0, and the above tetramethoxysilane-derived silica solution (Additive substance I) adjusted to 10 ° C. 1080 g Was added at a rate of 1.2 g / min to obtain a silica-based particle dispersion. This was concentrated by an RE apparatus, and adjusted to pH 9 with 3 mass% ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ . The average particle size of the silica-based particles was 180 nm, the standard deviation was 21.6 nm, and the CV value was 0.12.

(Example 18)
100 g of solution B prepared in the same manner as in Example 12 was collected and mixed with 200 g of pure water to prepare a seed solution. On the other hand, 63 g of tetramethoxysilane was added to 1017 g of pure water to prepare a silica solution (additive substance I) having a silica concentration of 2.3 mass%. Furthermore, a 5% by mass zirconia solution (Additive substance II) was prepared in terms of ZrO _{2 obtained} by diluting tetraisoproxioxyzirconium (ZA-40, manufactured by Matsumoto Fine Chemical Co., Ltd.) with ethyl alcohol.
As seeding, while stirring the seed solution, it was heated to 80 ° C. and held for 0.5 hours. Subsequently, to the seed solution, a 3% by mass ammonia solution was added to control the pH of the solution to 9.0, and the above tetramethoxysilane-derived silica solution (Additive substance I) adjusted to 10 ° C. 1080 g Were added at a rate of 3.6 g / min, and at the same time 20 g of the above zirconia solution (Additive substance II) was added at 0.07 g / min to obtain a silica-based particle dispersion of a composite oxide of silica and zirconia. This was concentrated by an RE apparatus, and adjusted to pH 9 with 3 mass% ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ -ZrO ₂ . The average particle size of the silica-based particles was 24.5 nm, the standard deviation was 4.9 nm, and the CV value was 0.20.

(Example 19)
100 g of solution B prepared in the same manner as in Example 12 was collected and mixed with 200 g of pure water to prepare a seed solution. On the other hand, 63 g of tetramethoxysilane was added to 1017 g of pure water to prepare a silica solution (additive substance I) having a silica concentration of 2.3 mass%. Furthermore, a 5% by mass titania solution (Additive substance II) was prepared in terms of TiO _{2 obtained} by diluting tetraisoproxy titanium (TA-10 manufactured by Matsumoto Fine Chemical Co., Ltd.) with ethyl alcohol.
As seeding, while stirring the seed solution, it was heated to 80 ° C. and held for 0.5 hours. Subsequently, to the seed solution, a 3% by mass ammonia solution was added to control the pH of the solution to 9.0, and the above tetramethoxysilane-derived silica solution (Additive substance I) adjusted to 10 ° C. 1080 g At a rate of 3.6 g / min and simultaneously 20 g of the titania solution (Additive Substance II) at 0.07 g / min to obtain a silica-based particle dispersion of a composite oxide of silica and titania. This was concentrated by an RE apparatus, and adjusted to pH 9 with 3 mass% ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ -TiO ₂ . The average particle size of the silica-based particles was 25.3 nm, the standard deviation was 6.0 nm, and the CV value was 0.24. Details are shown in Table 3 (same below).

Example 20
100 g of a solution C prepared in the same manner as in Example 12 except that N ₂ micro-nano bubble water was used instead of the O ₂ micro-nano bubble water was collected and mixed with 200 g of N ₂ micro-nano bubble water to prepare a seed solution. On the other hand, 63 g of tetramethoxysilane was added to 1017 g of N ₂ micro-nano bubble water to prepare a silica solution (additive substance I) having a silica concentration of 2.3 mass%. Furthermore, a 5% by mass alumina solution (Additive substance II) was prepared in terms of Al ₂ O _{3 obtained} by diluting a solution of triisoproxy aluminum (manufactured by Tokyo Chemical Industry Co., Ltd.) with ethyl alcohol.
As seeding, while stirring the seed solution, it was heated to 80 ° C. and held for 0.5 hours. Subsequently, to the seed solution, a 3% by mass ammonia solution was added to control the pH of the solution to 9.0, and the above tetramethoxysilane-derived silica solution (Additive substance I) adjusted to 10 ° C. 1080 g Were added at a rate of 3.6 g / min and simultaneously 20 g of the above alumina solution (Additive substance II) was added at 0.07 g / min to obtain a silica-based particle dispersion of a composite oxide of silica and alumina. This was concentrated by an RE apparatus, and adjusted to pH 9 with 3 mass% ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ -Al ₂ O ₃ . The average particle size of the silica-based particles was 24.0 nm, the standard deviation was 4.3 nm, and the CV value was 0.18.

(Example 21)
100 g of solution B prepared in the same manner as in Example 12 was collected and mixed with 200 g of pure water to prepare a seed solution.
On the other hand, 97 g of tetraethoxysilane was added while stirring 4070 g of modified ethyl alcohol (AP-11) to prepare a solution (third solution) for grain growth. Next, 4855 g of O ₂ micro-nano bubble water (second solution) prepared in the same manner as in Example 12 was added to the third solution, and reacted at 25 ° C. for 5 hours to obtain a silica particle dispersion. The silica particle dispersion was concentrated to 1860 g using an RE apparatus. To this solution was added 2000 g of pure water, and the mixture was concentrated by an RE apparatus to obtain 1860 g of a concentrated solution. The operation of adding this pure water and concentrating with the RE apparatus was repeated twice to obtain an aqueous dispersion. This was further concentrated to 600 g using an RE apparatus to obtain D liquid. To this solution D, 480 g of O ₂ micro-nano bubble water was added to prepare a silica solution (additive substance I) having a silica concentration of 2.3 mass%.

As seeding, while stirring the seed solution, it was heated to 80 ° C. and held for 0.5 hours. Subsequently, to the seed solution, a 3% by mass ammonia solution was added to control the pH of the solution to 9.0, and the above tetraethoxysilane-derived silica solution (Additive substance I) adjusted to 10 ° C. (1080g) Was added at a rate of 7.2 g / min to obtain a silica-based particle dispersion. This was concentrated by an RE apparatus, and adjusted to pH 9 with 3 mass% ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ . The average particle size of the silica-based particles was 22.0 nm, the standard deviation was 4.6 nm, and the CV value was 0.21.

(Example 22)
<Fine particle preparation process>
A solution (first solution) was prepared by adding 14.2 g of tetramethoxysilane while stirring 819.2 g of denatured ethyl alcohol (AP-11). 971 g of O ₂ micro-nano bubble water (second solution) prepared in the same manner as in Example 12 was added to the first solution and reacted at 25 ° C. for 5 hours to obtain a silica particle dispersion (liquid E). .

  The solution E was concentrated to 375 g using an RE apparatus. To this solution was added 450 g of pure water, and the mixture was concentrated by an RE apparatus to obtain 300 g of a concentrated solution. The operation of adding this pure water and concentrating with the RE apparatus was repeated twice to obtain an aqueous dispersion. Thereafter, the pH was adjusted to 9.3 using 3 mass% ammonia water and pure water, to obtain a silica particle dispersion (liquid F) dispersed in water having a silica concentration of 1 mass%. The average particle size of the silica particles in the F liquid was 5 nm.

Particle Growth Process
100 g of the solution F prepared in the fine particle preparation step was collected and mixed with 200 g of pure water to make a seed solution. On the other hand, 63 g of tetramethoxysilane was added to 1017 g of O ₂ micro-nano bubble water to prepare a silica solution (additive substance I) having a silica concentration of 2.3 mass%.
As seeding, while stirring the seed solution, it was heated to 80 ° C. and held for 0.5 hours. Subsequently, to the seed solution, a 3% by mass ammonia solution was added to control the pH of the solution to 9.0, and the above tetramethoxysilane-derived silica solution (Additive substance I) adjusted to 10 ° C. 1080 g Was added at a rate of 3.6 g / min to obtain a silica-based particle dispersion. This was concentrated by an RE apparatus, and adjusted to pH 9 with 3 mass% ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ . The average particle size of the silica-based particles was 21.5 nm, the standard deviation was 4.1 nm, and the CV value was 0.19.

(Example 23)
A solution E prepared in the same manner as in Example 22 was concentrated to 375 g using an RE apparatus. To this solution was added 450 g of pure water, and the mixture was concentrated by an RE apparatus to obtain 300 g of a concentrated solution. The operation of adding this pure water and concentrating with the RE apparatus was repeated twice to obtain an aqueous dispersion. Thereafter, the pH was adjusted to 7.0 using 3% by mass ammonia water and pure water, to obtain a silica particle dispersion (liquid G) dispersed in water with a silica concentration of 0.33% by mass. The average particle size of the silica particles in the G liquid was 5 nm.

Particle Growth Process
300 g of solution G prepared in the fine particle preparation step was collected and used as a seed solution. On the other hand, 63 g of tetramethoxysilane was added to 1017 g of O ₂ micro-nano bubble water to prepare a silica solution (additive substance I) having a silica concentration of 2.3 mass%.
As a seeding, it hold | maintained for 5 minutes at pH 7.0 and 25 degreeC, stirring a seed solution. Subsequently, while simultaneously adding a 3% by mass ammonia solution and the above-mentioned tetramethoxysilane-derived silica solution (added substance I) adjusted to 10 ° C. to the seed solution, the pH of the reaction solution is 9.0, The temperature was adjusted to 80 ° C. After the pH of the reaction solution reached 9.0 and the temperature reached 80 ° C., both solutions were added while controlling the pH and temperature to be constant to obtain a silica-based particle dispersion. Incidentally, 1080 g of the silica solution (Additive substance I) was added at a rate of 3.6 g / min. The obtained silica-based dispersion was concentrated by an RE apparatus, and adjusted to pH 9 with 3% by mass aqueous ammonia. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ . The average particle size of the silica-based particles was 22.0 nm, the standard deviation was 4.6 nm, and the CV value was 0.21.

(Comparative example 4)
<Fine particle preparation process>
While stirring 814 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 19.4 g of tetraethoxysilane. Further, 971 g of pure water, which is a second solution, was added to the first solution and reacted at 25 ° C. for 5 hours to obtain a solution A. No particles were generated in this A solution.

  The solution A was concentrated to 375 g using an RE apparatus. 450 g of pure water was added to this solution, and 300 g of a concentrated solution was obtained with an RE apparatus. The operation of adding this pure water and concentrating with the RE apparatus was repeated twice to obtain an aqueous dispersion. Then, it adjusted to pH 9.3 using 3% ammonia water and a pure water, and obtained the dispersion liquid (H liquid) disperse | distributed to 1 mass% concentration water. Silica particles in solution H were not detected. Details are shown in Table 3 (same below).

Particle Growth Process
100 g of the solution H prepared in the fine particle preparation step was collected and mixed with 200 g of pure water to obtain a seed solution (containing no particles). On the other hand, the silica solution obtained by cation exchange of No. 3 water glass having a silica concentration of 2.5 mass% is cation exchanged again to prepare a silica solution having a silica concentration of 2.3 mass% (additive substance I) did.
As seeding, the seed solution was heated to 80 ° C. and maintained for 0.5 hours while being stirred. Subsequently, while controlling the pH of the solution to 9.0 by adding a 3% by mass ammonia solution, 3.6 g / min of the above-mentioned water glass-derived silicate liquid (additive substance I) adjusted to 10 ° C. The addition was performed at a speed to obtain a silica-based particle dispersion. This was concentrated by an RE apparatus, and adjusted to pH 9 with 3 mass% ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ . The average particle size of the silica-based particles was 14 nm, the standard deviation was 4.9 nm, and the CV value was 0.35, indicating a broad particle size distribution. Details are shown in Table 3 (same below).

(Comparative example 5)
<Fine particle preparation process>
While stirring 814 g of modified ethyl alcohol (AP-11), a solution (first solution) was prepared by adding 19.4 g of tetraethoxysilane. Further, a mixed solution of 971 g of pure water as a second solution and 10 g of 15% by mass ammonia water is added to the first solution, and reacted at 25 ° C. for 5 hours to obtain a silica particle dispersion (liquid A). The

The solution A was concentrated to 375 g using an RE apparatus. To this solution was added 450 g of water, and 300 g of a concentrated solution was obtained with an RE apparatus. The operation of adding this pure water and concentrating with the RE apparatus was repeated twice to obtain an aqueous dispersion. Thereafter, the pH was adjusted to 9.3 using 3% by mass ammonia water and pure water, and a dispersion liquid (liquid J) dispersed in 1% by mass water was obtained. The silica particles in the solution J had an average particle size of 250 nm.
Particle Growth Process
100 g of the solution J prepared in the fine particle preparation step was collected and mixed with 200 g of pure water to prepare a seed solution. On the other hand, 63 g of tetramethoxysilane was added to 1017 g of pure water to prepare a silica solution (additive substance I) having a silica concentration of 2.3 mass%.
As seeding, while stirring the seed solution, it was heated to 120 ° C. and held for 0.5 hours. Subsequently, while controlling the pH of the solution to 9.0 by adding a 3% by mass ammonia solution, the above-mentioned tetramethoxysilane-derived silica solution (additional substance I) 1080g adjusted to 10 ° C. is 1.2 g / min. The addition was carried out at the speed of to obtain a silica particle dispersion. This was concentrated by an RE apparatus, and adjusted to pH 9 with 3 mass% ammonia water. The concentration of the produced silica-based particle dispersion was 10% by mass in terms of SiO ₂ . The average particle size of the silica-based particles was 310 nm, the standard deviation was 65.1 nm, and the CV value was 0.21, indicating a broad particle size distribution.

Claims (9)

A fine particle preparation step of hydrolyzing a silane alkoxide in a liquid phase containing microbubbles having an average bubble diameter of 40 nm to 10 μm to prepare silica fine particles having an average particle diameter of 3 to 10 nm;
A particle growth step of adding a hydrolysable metal compound to the dispersion containing the silica fine particles in the presence of an alkali catalyst to hydrolyze the dispersion, thereby growing the silica fine particles;
A method of producing a silica-based particle dispersion liquid, comprising:   The method for producing a silica-based particle dispersion liquid according to claim 1, wherein the silica-based particles produced in the particle growth step are particles having an average particle diameter of more than 10 nm and 300 nm or less.   The method for producing a silica-based particle dispersion liquid according to claim 1 or 2, wherein at least one of silane alkoxide and silicic acid is used as the hydrolyzable metal compound.   As the hydrolysable metal compound, a hydrolysable metal compound containing silicon and at least one of a hydrolysable metal compound containing a metal selected from titanium, zirconia, aluminum, tin and indium are used. Item 3. A method for producing a silica-based particle dispersion according to item 1 or 2.   The method for producing a silica-based particle dispersion according to any one of claims 1 to 4, wherein the hydrolysis in the particle growth step is performed in the presence of microbubbles having an average cell diameter of 40 nm to 10 m. 6. The method for producing a silica-based particle dispersion according to claim 5, wherein the dispersion to be hydrolyzed in the particle growth step contains the microbubbles at 1.0 × 10 ⁵ / mL or more.   The method for producing a silica-based particle dispersion liquid according to claim 5 or 6, wherein the micro bubbles are bubbles containing at least one of nitrogen, hydrogen, oxygen, ozone, carbon dioxide gas, and a rare gas.   A silica-based particle dispersion liquid comprising silica-based particles having an average particle diameter of more than 10 nm and 300 nm or less and microbubbles having an average bubble diameter of 40 nm to 10 μm. A complex metal oxide comprising: a silica core particle having an average particle diameter of 3 to 10 nm; silicon surrounding the silica core particle; and at least one metal selected from titanium, zirconia, aluminum, tin and indium The silica-based particle dispersion liquid according to claim 8, comprising an object layer.