JP2018123043A - Method for producing silica-based particle dispersion, silica-based particle dispersion, coating liquid for forming transparent coating film, and substrate with transparent coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a silica-based particle dispersion, which enables production of silica-based hollow particles in a high ratio, having a size such that the average particle diameter is smaller than 50 nm.SOLUTION: Provided is a method for producing a dispersion containing silica-based particles, where the particles have an average particle diameter of 5 to 40 nm and a ratio (hollow ratio) of the number of hollow particles relative to the total number of hollow particles and solid particles is 70% or more. Specifically, the method comprises a first step of preparing a dispersion containing composite oxide particles by simultaneously adding, to a dispersion containing silica nuclear particles having an average particle diameter of 3 to 25 nm and sphericity of 1.0 to 1.5, at least either of an aqueous silicate solution or an acidic silicic acid solution, and an aqueous solution of an inorganic compound.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a dispersion containing silica-based hollow particles having an average particle diameter of 5 to 40 nm.

  Conventionally, in order to prevent reflection on the surface of a substrate such as glass, plastic sheet, plastic lens, etc., an antireflection film is formed on the surface. For example, a coating of a low refractive index material such as fluororesin or magnesium fluoride is formed on the surface of a glass or plastic substrate by a coating method, a vapor deposition method, a CVD method or the like, or a low refractive index fine particle such as a silica fine particle There is known a method of forming an antireflection coating by applying a coating solution containing selenium to a substrate surface (see, for example, Patent Document 1). At this time, in order to improve the antireflection performance, it is also known to form a high refractive index film containing fine particles of high refractive index under the antireflection coating.

  On the other hand, the present applicant has proposed a method for producing silica-based fine particles having cavities therein (see Patent Document 2). The silica-based fine particles obtained by this method have a low refractive index, and the transparent film formed using the silica-based fine particles has a low refractive index and excellent antireflection performance.

  The applicant of the present application discloses that when such a transparent coating is formed on the front surface of a display device and used, the antireflection performance is excellent and the display performance is improved (see Patent Document 3).

  Further, the applicant of the present application is that the number ratio of the irregular-shaped silica-based hollow fine particles having a particle diameter of twice or more the average particle diameter (Dn) in the silica hollow fine particles is 1% or less and the average particle diameter is in the range of 50 to 120 nm. When low-refractive-index silica-based hollow microparticles having a particle diameter variation coefficient (CV value) of 1 to 50% or less are used, whitening is suppressed, and transparency, haze, antireflection, strength, and scratch resistance are excellent. It is disclosed that a transparent coated substrate can be obtained (see Patent Document 4).

JP-A-7-133105 JP 2001-233611 A JP 2002-079616 A Japanese Unexamined Patent Publication No. 2012-30489

As shown in Patent Documents 2 to 4, it has been possible to obtain silica-based hollow particles having an average particle diameter larger than 50 nm. However, when obtaining a particle having an average particle size smaller than 50 nm, the reproducibility is low, and the ratio of the number of hollow particles to the total number of hollow particles and solid particles (hollow rate) is a problem. It was. And the film produced using the coating liquid containing such particles has a problem that the refractive index is not sufficiently lowered, and it cannot be practically used for an antireflection film or the like.
The subject of this invention is providing the manufacturing method of the silica type particle dispersion liquid which makes it possible to manufacture the silica type hollow particle of an average particle size smaller than 50 nm in a high ratio.

  The present inventors paid attention to the sphericity of the core particles prepared from the seed particles of silica during the study for the production of silica-based hollow particles having a smaller particle size. Conventional core particles use particles having a high measured value of sphericity (not spherical) obtained as a ratio between the longest diameter and the shortest diameter of the particles.

  However, it has been found that when such a core particle having a high measured value of sphericity is used, in the production of hollow particles smaller than 50 nm, the hollow ratio is reduced.

  Therefore, the present inventors use an average particle diameter of 5% or more in which hollow particles occupy a ratio of 70% or more by using nuclear particles having a low measured sphericity (particles that are more spherical and close to true sphere). It has been found that 40 nm silica-based hollow particles can be produced, and the present invention has been completed.

That is, the present invention provides a dispersion of silica-based particles having an average particle diameter of 5 to 40 nm and a ratio of the number of hollow particles to the total number of hollow particles and solid particles (hollow ratio) of 70% or more. It relates to a method of manufacturing. This method includes the following first to fourth steps.
(1) In a dispersion containing silica core particles having an average particle size of 3 to 25 nm and a sphericity of 1.0 to 1.5, at least one of a silicate aqueous solution and an acidic silicate solution, and an inorganic material containing no silicon A first step of adding a compound aqueous solution at the same time to prepare a dispersion containing composite oxide particles.
(2) Second step of preparing a dispersion containing coated composite oxide particles coated with a layer containing silica by adding a silica source to the dispersion containing composite oxide particles obtained in the first step.
(3) A third step of removing an element derived from the inorganic compound contained in the coated composite oxide particles by adding an acid to the dispersion containing the coated composite oxide particles obtained in the second step.
(4) A fourth step in which the dispersion containing the particles obtained in the third step is hydrothermally treated under alkaline conditions.

  Further, the present invention is a silica comprising silica-based particles having an average particle diameter of 5 to 40 nm and a ratio of the number of hollow particles to the total number of hollow particles and solid particles (hollow ratio) of 70% or more. The present invention relates to a dispersion of system particles.

Moreover, this invention relates to the coating liquid for transparent film formation containing the said silica type particle | grain, a matrix formation component, and a polar solvent.
Furthermore, the present invention includes a base material and a transparent coating film formed on the base material and containing the silica-based particles and the matrix component, and the content of the silica-based particles in the transparent coating film is 20 to 80% by mass. It is related with the base material with a transparent film which is.

  The present invention relates to a dispersion of silica-based particles having an average particle diameter of 5 to 40 nm and a ratio of the number of hollow particles to the total number of hollow particles and solid particles (hollow ratio) of 70% or more, and A manufacturing method is provided. The substrate with a transparent coating prepared with a coating solution containing silica-based particles exhibits a sufficiently low refractive index and has high antireflection performance, and is composed of relatively small particles, so it has high transparency and is whitened. The phenomenon is suppressed and it has sufficient adhesion, scratch resistance, magic resistance, water resistance, and alkali resistance.

It is this schematic which shows the concept of the base material with a transparent film of this invention typically. It is this schematic which shows the concept of the base material with a transparent film using the conventional hollow particle typically.

[Method for producing dispersion of silica-based particles]
The present invention produces a dispersion of silica-based particles having an average particle diameter of 5 to 40 nm and a ratio of the number of hollow particles to the total number of hollow particles and solid particles (hollow ratio) of 70% or more. The method includes at least the following steps. It is particularly characterized in that the shape of the core particles in the first step is adjusted.
(1) An inorganic compound aqueous solution not containing silicon and at least one of a silicate aqueous solution and an acidic silicate solution in a dispersion containing core particles having an average particle diameter of 3 to 25 nm and a sphericity of 1.0 to 1.5 Are added simultaneously to prepare a dispersion containing composite oxide particles.
(2) Second step of preparing a dispersion containing coated composite oxide particles coated with a layer containing silica by adding a silica source to the dispersion containing composite oxide particles obtained in the first step.
(3) A third step of removing an element derived from the inorganic compound contained in the coated composite oxide particles by adding an acid to the dispersion containing the coated composite oxide particles obtained in the second step.
(4) A fourth step in which the dispersion containing the particles obtained in the third step is hydrothermally treated under alkaline conditions.

  Conventionally, the production of hollow particles having an average particle diameter of less than 50 nm has been problematic in that the reproducibility is low and the hollow ratio is low. In the present invention, it has been found that the cause of the difficulty in producing hollow particles having an average particle diameter of less than 50 nm is the sphericity of the core particles, and by improving this, the ratio of the hollow particles in the whole particles is 70. % Or more of silica-based particles can be produced.

<pre-process>
In order to obtain core particles in the desired range of the present invention, it is preferable to employ at least one of the following conditions (A) and (B).
(A) Core particles are prepared using seed particles having an average particle diameter of 8 nm or more.
(B) The seed particles are held under a temperature of 80 ° C. or lower and / or a pH of 12 or lower to prepare core particles.
That is, (A) using a relatively large seed particle, preparing a core particle with a measured value of sphericity close to 1.0, or (B) under conditions where the particle stability of the seed particle is high It is preferable to prepare the core particles, and it is particularly preferable to manufacture the core particles under conditions that satisfy (A) and (B).

First, (A) conditions for using seed particles having an average particle diameter of 8 nm or more will be described.
This condition is characterized in that seed particles having a relatively large seed particle diameter are used. That is, in the past, in order to produce hollow particles having a high porosity, particles having an average particle diameter of about 5 nm were used from the knowledge that smaller seed particles are preferable. It is characterized in that seed particles having a large particle diameter are applied. Due to the large particle size of the seed particles, the stability of the seed particles is maintained when preparing the core particles. As a result, the measured sphericity is close to 1.0 (close to the true sphere). Can be formed. If it is a seed particle of this particle diameter, the conditions at the time of preparing a core particle can also apply the pH conditions and temperature conditions similar to the past. Furthermore, it is preferable to apply the condition (B) in combination.
As described above, the average particle diameter of the seed particles is preferably 8 nm or more, more preferably 10 to 50 nm, and more preferably 10 to 30 nm, from the viewpoint of stability of the seed particles in the preparation of the core particles. Further preferred is 10 to 20 nm.

Next, (B) conditions for holding the seed particles under conditions of a temperature of 80 ° C. or lower and / or a pH of 12 or lower will be described.
This condition is characterized in that the core particles are generated under the condition that the seed particles maintain the stability as the seed particles. That is, conventionally, relatively high temperature and high pH conditions have been applied in the preparation of the core particles so that the particle growth of the core particles proceeds rapidly. The final product produced under such conditions was not inconvenient as conventional hollow particles, but when producing hollow particles having an average particle diameter of less than 50 nm, the reproducibility is low and the hollowness ratio is low. There was a problem of lowering. For this reason, this condition (B) changes this temperature and / or pH conditions. This condition (B) is a low temperature and low pH condition as compared with the prior art. Since the stability of the seed particles during the growth of the core particles is maintained, the measured sphericity is 1. Nuclear particles close to 0 (nearly spherical) can be formed. Under these temperature and pH conditions, desired core particles can be obtained even when conventional particles having a small average particle diameter of about 5 nm are used. That is, seed particles having an average particle diameter of 3 nm or more and less than 8 nm can be used, and preferably seed particles having a particle diameter of 5 nm or more and less than 8 nm can also be used. Furthermore, it is preferable to apply the condition (A) in combination.

  As described above, the condition for obtaining the core particles in the desired range of the present invention is preferably a temperature of 80 ° C. or lower and / or pH of 12 or lower, and the temperature is more preferably 70 ° C. or lower, More preferably, it is 50-65 degreeC. As pH, it is more preferable that it is 11.5 or less, and it is further more preferable that it is 9.0-11.0. In addition, when employ | adopting conditions (B) in this process, it is preferable to maintain conditions (B) also in the 1st process of the following process.

  The solid content concentration of the dispersion when preparing the core particles from the seed particles is preferably 0.1 to 20% by mass, and more preferably 0.3 to 10% by mass. When the solid content concentration of the dispersion containing the seed particles is less than 0.1% by mass, the solubility per seed particle increases and the generation of the core particles cannot be moderated, so that the desired core particles cannot be obtained. There is a case. Moreover, since the efficiency in manufacturing falls, it is not preferable. On the contrary, if the solid content concentration exceeds 20% by mass, the dispersion is not stable and the particles may aggregate.

<First step>
In the first step, the dispersion containing silica core particles having an average particle diameter of 3 to 25 nm and a sphericity of 1.0 to 1.5 contains at least one of an aqueous silicate solution and an acidic silicate solution, and silicon. A dispersion containing composite oxide particles (primary particles) is prepared by simultaneously adding a nonaqueous inorganic compound aqueous solution. The core particles used in this step are core particles prepared using seed particles in the previous step.

Here, if the average particle diameter of the core particles is less than 3 nm, it is difficult to obtain particles having the particle diameter itself, and even if it is obtained, in the preparation of the composite oxide particle dispersion, it is homogeneous. Particle growth may not be possible. As a result, silica particles having a hollowness of 70% or more may not be obtained. Conversely, if the average particle diameter of the core particles exceeds 25 nm, silica-based hollow particles having a desired average particle diameter in the range of 5 to 40 nm in the subsequent steps may not be obtained. The average particle diameter of the core particles is preferably 5 to 20 nm.
Further, if the sphericity of the core particles is outside the range of 1.0 to 1.5, the number of non-spherical particles increases, so that silica particles having a desired hollowness of 70% or more are obtained in the subsequent steps. I can't.

The preparation of the composite oxide particle dispersion in the first step is preferably performed in a range of solid content concentration of 0.1 to 0.9% by mass, and further 0.2 to 0.6% by mass. The solid content concentration of this dispersion is such that at least one of a silicate aqueous solution and an acidic silicate liquid and an inorganic compound aqueous solution not containing silicon are simultaneously added to the dispersion containing the core particles, and the addition is completed. It is preferable that it is maintained up to the time point.
If this concentration is lower than 0.1% by mass, the yield decreases and the production efficiency decreases, which is not preferable.
On the other hand, when the concentration is higher than 0.9% by mass, homogeneous particle growth is not performed, and as a result, silica-based particles having a hollow ratio of 70% or more may not be obtained.

  When preparing the core particles, it is preferable to control the particle growth rate within a suitable range. The particle growth rate at this time varies depending on the particle diameter of the core particle, but is preferably 0.1 to 10 nm / hour, more preferably 0.2 to 5 nm / hour, and further preferably 0.2 to 3 nm / hour. It is a range.

  As means for carrying out particle growth in the above range, the concentration of the mother liquor containing the core particles and the reaction solution is lowered, the concentration of the silica source such as the diluted silicate aqueous solution and the acidic silicate solution added, and the concentration of the inorganic compound aqueous solution. And lowering the reaction temperature (controlling the rate of addition of these added solutions to the core particle dispersion, lowering the reaction temperature (temperature during particle growth), and the like.

As the silicate used in this step, one or more silicates selected from alkali metal silicates, ammonium silicates and organic base silicates are preferably used.
Examples of the alkali metal silicate include sodium silicate (water glass) and potassium silicate. Examples of the organic base include quaternary ammonium salts such as tetraethylammonium salt, and amines such as monoethanolamine, diethanolamine, and triethanolamine. Ammonium silicate or organic base silicate includes a silicate liquid. Also included are alkaline solutions in which ammonia, quaternary ammonium hydroxides, amine compounds and the like are added.

The inorganic compound used in this step is substantially composed of an element other than silicon, and is a compound that is soluble in acid and alkali. When this is expressed by an oxide (MOx), MOx is Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , CeO ₂ , P ₂ O ₅ , Sb ₂ O ₃ , MoO ₃ , ZnO, One or more of WO _{3 and the} like, and examples of the composite oxide include TiO ₂ —Al ₂ O ₃ and TiO ₂ —ZrO ₂ . Examples of the inorganic compound used in this step include alkali metal salts, alkaline earth metal salts, ammonium salts, and quaternary ammonium salts of metal or non-metal oxo acids that constitute these inorganic oxides. For example, sodium aluminate, sodium tetraborate, ammonium zirconium carbonate, potassium antimonate, potassium stannate, sodium aluminosilicate, sodium molybdate, cerium ammonium nitrate, sodium phosphate and the like are suitable.

In the first step, the silica derived from at least one of the silicate aqueous solution and the acidic silicate solution is represented by SiO ₂ , and the molar ratio MO _X / SiO when the inorganic compound derived from the inorganic compound aqueous solution is represented by MO _X as an oxide. ₂ is preferably 0.15 to 3.0. When the molar ratio MO _X / SiO ₂ is in the range of 0.15 to 3.0, the composite oxide particles have a structure in which silicon and elements other than silicon are mainly bonded alternately with oxygen interposed therebetween. That is, oxygen atoms are bonded to the four bonds of silicon atoms, and a large number of structures in which elements M other than silicon are bonded to these oxygen atoms are produced. In the second step, the inorganic compound contained in the coated composite oxide particles When the element derived from is removed, the silicon atom can be removed as a silicate monomer or oligomer in association with the element (M). Here, when MO _X / SiO ₂ is less than 0.15, the hollow volume in the hollow particles is not sufficiently large, and when MO _X / SiO ₂ exceeds 3.0, spherical composite oxide particles can be obtained. As a result, the ratio of the porosity (cavity volume) in the obtained hollow particles decreases.
A more preferable molar ratio MO _X / SiO ₂ is 0.15 to 2.0, and more preferably 0.2 to 1.0.

The composite oxide particles obtained in the first step preferably have an average particle diameter of 3 to 35 nm and a sphericity of 1.0 to 1.5.
Here, if the average particle size of the composite oxide particles is less than 3 nm, it is difficult to obtain particles of that particle size, and even if obtained, the composite oxide particles have silica content. When forming many coating layers, homogeneous particle growth is not performed, and as a result, silica-based particles having a desired hollowness of 70% or more may not be obtained. Conversely, if the average particle diameter exceeds 35 nm, silica-based particles having a desired average particle diameter in the range of 5 to 40 nm may not be obtained in the subsequent steps. In addition, if the sphericity of the composite oxide particles is outside the range of 1.0 to 1.5, the number of non-spherical particles increases. Therefore, in the subsequent steps, a silica-based particle having a desired hollowness of 70% or more Cannot be obtained.

<Second step>
In the second step, a silica source is added to the dispersion containing the composite oxide particles obtained in the first step to prepare a dispersion containing coated composite oxide particles coated with a layer containing silica. As a silica source, the above-mentioned silicate aqueous solution, acidic silicic acid liquid, and these hydrolysates are mentioned.

In this step, in addition to the silica source, an inorganic compound containing no silicon used in the first step can also be added. That is, at least one of the silicate solution and an acidic silicic acid solution and an inorganic compound aqueous solution was added with a small molar ratio _MO X / SiO ₂ than the molar ratio _MO X / SiO ₂ of the first step described above, the composite oxide It is also preferable to form a coating layer containing a large amount of silica containing silica and an inorganic compound other than silica on the product particles.

Here, if the molar ratio in the second step _MO X / SiO ₂ is smaller molar ratio than the molar ratio _MO X / SiO ₂ of the first step, the coating layer increases the amount of silica, the later During the acid treatment in the three steps, the element M other than silicon is removed, and a coating layer substantially made of silica is formed.

In particular, the ratio (B / A) of the molar ratio (B) of MO _X / SiO ₂ in the second step to the molar ratio (A) of MO _X / SiO ₂ in the first step is preferably 0.8 or less. . The value (B / A) is more preferably 0.6 or less, and the value (B / A) is more preferably 0.5 or less.

In the formation of the coating layer containing silica in the second step, the solid content concentration of the dispersion containing the composite oxide particles is in the range of 0.1 to 0.9% by mass, and further 0.2 to 0.6% by mass. It is preferable to carry out with.
If this concentration is lower than 0.1% by mass, the yield decreases and the production efficiency decreases, which is not preferable.
On the other hand, when the concentration is higher than 0.9% by mass, homogeneous particle growth is not performed, and as a result, silica-based particles having a hollow ratio of 70% or more may not be obtained.

  When forming the coating layer containing silica, it is preferable to control the formation rate of the coating layer within a suitable range. The formation rate at this time varies depending on the particle size of the primary particles of the composite oxide particles, but is preferably 0.1 to 10 nm / hour, more preferably 0.2 to 5 nm / hour, still more preferably 0.2 to The range is 3 nm / hour.

  The means for forming the coating layer within the above range includes reducing the concentration of the mother liquor and reaction solution containing the composite oxide particles, adding an organosilicon compound solution, dilute silicate aqueous solution and acidic silicate solution such as silica. Reduce the concentration of the source and the inorganic compound aqueous solution not containing silicon, control the rate of addition of these additive solutions to the composite oxide particle dispersion, and lower the reaction temperature (temperature at which the coating layer is formed) This is exemplified.

  In the first step and / or the second step, it is preferable to perform aging by hydrothermal treatment after the grain growth and / or after the formation of the coating layer containing silica. The aging at this time is preferably carried out in a range where the solid content concentration is 1 to 30% by mass, the temperature is 30 to 100 ° C., and the time is 1 to 12 hours.

  In the first step and / or the second step, it is preferable to prevent the aggregation by irradiating ultrasonic waves or the like to achieve high dispersion. If aggregated particles or coarse particles that are difficult to disperse are present, it is preferable to remove them by a capsule filter, centrifugation, or the like.

The coated composite oxide particles obtained in the second step preferably have an average particle diameter of 5 to 40 nm and a sphericity of 1.0 to 1.5.
Here, when the average particle size of the coated composite oxide particles is less than 5 nm, it is difficult to obtain particles having the particle size itself, and even if obtained, the desired average particles in the subsequent steps. Silica-based particles having a diameter in the range of 5 to 40 nm may not be obtained. Further, in the subsequent steps, silica-based particles having a desired hollowness of 70% or more may not be obtained. On the other hand, even if the average particle diameter exceeds 40 nm, it is not preferable because silica particles having a desired average particle diameter in the range of 5 to 40 nm may not be obtained in the subsequent steps.
In addition, if the sphericity of the coated composite oxide particles is outside the range of 1.0 to 1.5, the number of non-spherical particles increases. Particles cannot be obtained.

<Third step>
In the third step, an acid is added to the dispersion containing the coated composite oxide particles obtained in the second step to remove elements derived from the inorganic compound contained in the coated composite oxide particles. That is, by removing the metal element constituting the inorganic compound not containing silicon added in the first step (second step if necessary) from the coated composite oxide particles, hollow particles having cavities therein are produced. To do.

  Examples of the method for removing the element derived from the inorganic compound contained in the coated composite oxide particles include a method for dissolving and removing using at least one of a mineral acid and an organic acid. Moreover, the method of making it contact with cation exchange resin and removing ion exchange, or the method of using these together can be illustrated.

  The concentration of the coated composite oxide particles in the coated composite oxide particle dispersion at this time varies depending on the treatment temperature, but is 0.1 to 50% by mass, particularly 0.5 to 25% by mass in terms of oxide. It is preferable that it exists in the range. If it is less than 0.1% by mass, silica may be dissolved in the silica coating layer, and at the same time, the treatment efficiency is poor due to the low concentration. On the other hand, when the concentration of the coated composite oxide particles exceeds 50% by mass, it is difficult to remove the desired amount of the element derived from the inorganic compound contained in the coated composite oxide particles with a small number of times.

The removal of the element derived from the above-mentioned inorganic compound is performed until the molar ratio MO _X / SiO _{2 of the} silica-based particles obtained is 0.0001 to 0.2, particularly 0.0001 to 0.1. preferable. The dispersion from which the elements have been removed can be washed by a known washing method such as ultrafiltration. In this case, if part of alkali metal ions, alkaline earth metal ions, ammonium ions, etc. in the dispersion is removed in advance and then ultrafiltered, a sol in which particles having high dispersion stability are dispersed is obtained. An organic solvent-dispersed sol can be obtained by substituting with an organic solvent as necessary. The silica-based particles dispersed in the dispersion sol thus obtained have an outer shell composed of a porous silica layer and have cavities inside. If the core particles are not completely removed, a porous substance remains in the cavity. Therefore, the obtained hollow particles have a low refractive index, and a coating formed using the hollow particles has a low refractive index, so that a coating excellent in antireflection performance can be obtained.

<4th process>
In the fourth step, the dispersion containing the particles obtained in the third step is aged by hydrothermal treatment under alkaline conditions. By this step, hollow particles having a hollow ratio of 70% or more excellent in dispersion stability can be produced.

This hydrothermal treatment is preferably performed in a range of solid content concentration of 1 to 30% by mass, pH of 9.0 or more, temperature of 30 to 300 ° C., and time of 1 to 72 hours.
Silica-based particles aged by this hydrothermal treatment can be replaced with an organic solvent. The type of organic solvent is not particularly limited as long as it does not adversely affect the silica-based particles. Examples of usable organic solvents include alcohols, glycols, esters, ketones, nitrogen compounds, and aromatics. The method of solvent replacement is not particularly limited as long as the solvent replacement is performed, and for example, a conventionally known method of using an ultrafiltration membrane or a rotary evaporator may be used.

<5th process>
In the manufacturing method of this invention, it has the 5th process which surface-treats with the organosilicon compound represented by following formula (1), or these hydrolysates with respect to the hollow particle which passed through the said 1st-4th process. It is preferable.

_{R n -SiX 4-n (1} )
(In the formula, R is an unsubstituted or substituted hydrocarbon group having 1 to 10 carbon atoms and may be the same or different. X is an alkoxy group having 1 to 4 carbon atoms or a silanol group. , Halogen, hydrogen, n is an integer of 0 to 3)

  Examples of the organosilicon compound represented by the formula (1) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxy. Silane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (βmethoxyethoxy) silane, 3, 3, 3 -Trifluoropropyltrimethoxysilane, methyl-3,3,3-trifluoropropyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glyci Xymethyltrimethoxysilane, γ-glycidoxymethyltriexylsilane, γ-glycidoxyethyltrimethoxysilane, γ-glycidoxyethyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycid Xylpropyltriethoxysilane, γ- (β-glycidoxyethoxy) propyltrimethoxysilane, γ- (meth) acryloxymethyltrimethoxysilane, γ- (meth) acryloxymethyltriexylsilane, γ- (meth) Acryloxyethyltrimethoxysilane, γ- (meth) acryloxyethyltriethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxy Propyltriethoxysilane, γ- (meth) acryl Xypropyltriethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltriethoxysilaoctyltriethoxysilane, decyltriethoxysilane, butyltriethoxysilane, isobutyltriethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, Decyltriethoxysilane, 3-ureidoisopropylpropyltriethoxysilane, perfluorooctylethyltrimethoxysilane, perfluorooctylethyltriethoxysilane, perfluorooctylethyltriisopropoxysilane, trifluoropropyltrimethoxysilane, N-β ( Aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N- Eniru -γ- aminopropyltrimethoxysilane, .gamma.-mercaptopropyltrimethoxysilane, trimethylsilanol, methyl trichlorosilane and the like.

  When the silica-based particles are surface-treated with such an organosilicon compound, they can be uniformly dispersed in the matrix and densely packed, and a transparent film excellent in film strength and scratch resistance can be obtained. Can do.

  In the surface treatment of the silica-based particles, a predetermined amount of the above-mentioned organosilicon compound is added to the alcohol dispersion of the particles, water is added thereto, and if necessary, acid or alkali is added as a hydrolysis catalyst to hydrolyze the organosilicon compound. Decompose. More preferably, this is then heat-treated and aged.

The mass ratio of the silica-based particles and an organic silicon compound in this (solid organosilicon compound fraction (mass of _{R n -SiX (4-n)} / 2) as a mass / silica-based particles), silica-based particles Although it varies depending on the average particle size, it is preferably in the range of 0.005 to 3.0, more preferably 0.05 to 1.0.

  If the aforementioned mass ratio is less than 0.005, the affinity with the matrix-forming component described later is low, dispersibility in the paint, stability becomes insufficient, and particles may aggregate in the paint, A dense transparent film may not be obtained, and adhesion to the substrate, film strength, scratch resistance, and the like may be insufficient.

  On the contrary, when the above-mentioned mass ratio is larger than 30.0, the dispersibility in the paint is not further improved, the refractive index of the silica-based particles is increased, and a transparent film having a desired low refractive index is obtained. The antireflection performance may be insufficient.

[Dispersion of silica-based particles]
The silica-based particle dispersion of the present invention has an average particle diameter of 5 to 40 nm, and the ratio of the number of hollow particles to the total number of hollow particles and solid particles (hollow ratio) is 70% or more. It contains system particles. This can be manufactured by the manufacturing method described above. Conventionally, silica-based hollow particles having a small average particle diameter of 5 to 40 nm have been difficult to produce, but in the present invention, production at a high rate of a hollow ratio of 70% or more has been realized.

The antireflection film is generally wavelength-dependent and is often designed to be λ / 4 with respect to the wavelength λ, and usually has a minimum reflectance at a wavelength of 550 nm, which is highly visible to humans. Since it is designed, it is generally used as a thin film having a thickness of about 100 nm.
In the present invention, silica-based hollow particles having a comparatively small particle diameter of 5 to 40 nm can be produced. Therefore, the antireflection film containing such hollow particles is sufficiently filled with hollow particles in the thin film. Become. As a result, the smoothness of the particle surface is improved and the magic resistance, water resistance, and alkali resistance of the thin film can be improved. Moreover, since the hollow ratio is high, high antireflection performance can be exhibited. Furthermore, since the particle size is small even when the blending amount of the particles is relatively high, scattering by the particles is suppressed, and a highly transparent coating can be formed.

  Silica-based particles according to the dispersion of the present invention are particles mainly composed of silica having an average particle diameter of 5 to 40 nm. In addition to silica, the silica-based particles may contain oxides such as alumina and magnesia, alkali metal oxides and hydroxides. However, in terms of the use of the transparent film, it is preferable that the film is substantially made of silica.

<Measurement of average particle size>
The average particle diameter is obtained by taking an electron micrograph, measuring the longest diameter and the shortest diameter of each particle, and measuring the particle diameter of any 100 particles, using the average value as the particle diameter of the particle, and calculating the average It is obtained as a value.

If the average particle size of the silica-based particles is less than 5 nm, it is difficult to obtain particles of that particle size, and it is particularly difficult to obtain silica-based hollow particles. For example, even if silica-based hollow particles with this particle size are obtained, the particle size itself is small, so the proportion of cavities inside the particles is small, that is, the porosity is small, so the refractive index is high, and sufficient antireflection performance is achieved. In some cases, a transparent film having the above cannot be obtained. Furthermore, silica-based particles having a hollow ratio of 70% or more cannot be obtained.
On the contrary, when the average particle diameter exceeds 40 nm, the particles are large, and therefore, when blended into a thin film, they are not sufficiently embedded in the surface of the transparent coating. As a result, particles are exposed on the surface of the transparent coating, causing external scattering on the surface of the coating to reduce the transparency, and the smoothness of the surface of the transparent coating may be reduced, resulting in insufficient scratch resistance and the like.
A more preferable average particle diameter is 5 to 35 nm, and further preferably 8 to 30 nm.

  In the silica-based particles according to the dispersion of the present invention, the ratio of the number of hollow particles to the total number of hollow particles and solid particles (hollow rate) is 70% or more. Here, the hollow particle means a particle having a cavity inside and having a porosity of 3% or more, and the solid particle means a particle having a porosity of less than 3%.

<Measurement of porosity of individual particles>
Porosity is defined as the proportion of cavities in the particles in the particles. Specifically, a transmission electron micrograph of the particles is taken. At this time, the hollow portion of the hollow particle has a low density, and the contrast of the portion becomes low in the transmission electron micrograph. Therefore, the hollow portion of the hollow particle is compared with the outer shell portion of the hollow particle at the contrast ratio of the transmission electron micrograph. A hollow part can be confirmed. First, the longest diameter and the shortest diameter of the particles are measured, and the volume (V _Q ) on the assumption that the particle shape is a true sphere is obtained by using the average value as the particle diameter of the particles. Next, the longest diameter and the shortest diameter of the cavity portion of the particle are measured, and the volume (V _P ) assuming the shape of the cavity portion as a true sphere is obtained with the average value as the diameter of the cavity. The porosity is represented by the ratio of the volume (V _P ) to the volume (V _Q ).

<< Measurement of hollowness >>
As for the hollow ratio, 100 particles are confirmed by a TEM image, and the ratio of the number of hollow particles to the total number of hollow particles (porosity of 3% or more) and solid particles (porosity of less than 3%) is obtained. .

  If the hollowness is less than 70%, the refractive index of the transparent coating cannot be sufficiently reduced, although it depends on the content, particle size, or sphericity of the silica-based particles in the transparent coating. In some cases, antireflection performance may not be exhibited. The hollow ratio is preferably 75% or more, more preferably 80% or more, further preferably 90% or more, particularly preferably 95% or more, and most preferably 100%.

The porosity of the entire silica-based particles according to the dispersion of the present invention is preferably 3 to 50%, more preferably 15 to 50%, and still more preferably 25 to 48%.
<< The porosity of the entire silica-based particles >>
The porosity of the entire silica-based particles in the dispersion of the present invention is obtained by calculating the porosity of individual particles obtained as described above for 100 arbitrary particles and obtaining the average value thereof. The higher the porosity, the lower the refractive index. When such particles having a high porosity are blended in the transparent film, a film having high antireflection performance can be obtained.

The silica particles according to the dispersion of the present invention preferably have a sphericity of 1.0 to 1.5. If the sphericity of the silica-based particles is within this range, the particle shape is close to a sphere. For this reason, it becomes possible to uniformly fill the transparent film having a thin film thickness, and it is possible to form a thin film transparent film in which the silica-based particles are not exposed to the outside while maintaining the film surface smoothness. As a result, a film having a low refractive index and sufficient strength can be obtained, which is preferable. In addition, since a transparent film in which silica-based particles are not exposed to the outside from the film surface is easily obtained, whitening and scratch resistance are unlikely to occur. The number ratio of so-called irregularly shaped particles having a sphericity exceeding 1.5 is preferably 1% or less.
More preferable sphericity is 1.0 to 1.4, and further preferably 1.0 to 1.2.

<Measurement of sphericity>
The sphericity is defined as the ratio between the longest diameter and the shortest diameter of the particles. Specifically, a transmission electron micrograph is taken, the longest diameter and the shortest diameter of each particle are measured, and the ratio (ratio of the longest diameter to the shortest diameter) is determined for any 100 particles, and the average value is obtained. As obtained. The closer to a spherical sphere, the smaller the difference between the longest diameter and the shortest diameter, and the ratio (ie, sphericity) approaches 1.0.

<Measurement of the number ratio of irregularly shaped particles>
In the above-described measurement of sphericity, the ratio of the number of particles having a sphericity exceeding 1.5 with respect to arbitrary 100 particles is obtained.

  Moreover, it is preferable that the refractive index of the silica type particle which concerns on the dispersion liquid of this invention is 1.10-1.41. Since the silica-based particles include hollow particles and have a hollow ratio of 70% or more, the refractive index is lower than those composed only of ordinary silica-based solid particles.

  Those having a refractive index of less than 1.10 are difficult to obtain. On the other hand, if the refractive index is higher than 1.41, the refractive index of the transparent coating containing the silica-based particles is also increased, so that the antireflection performance may be insufficient. The refractive index is more preferably 1.10 to 1.30, still more preferably 1.10 to 1.25.

<Measurement of refractive index>
Further, the refractive index of the silica-based particles used in the present invention is measured by the following method.
[1] A dispersion of silica-based particles is taken in an evaporator and the dispersion medium is evaporated.
[2] This is dried at 120 ° C. to obtain a powder.
[3] A standard refraction liquid with a known refractive index is dropped on a glass plate in a few drops, and the above powder is mixed therewith.
[4] The operation of [3] is performed with various standard refractive liquids, and the refractive index of the standard refractive liquid when the mixed liquid becomes transparent is the refractive index of the silica-based particles.

  Moreover, it is preferable that the silica type particle | grains of this invention have the organic group directly couple | bonded with the silicon atom on the surface. That is, the surface-treated one in the fifth step in the production method of the present invention is preferable. About the kind of organic group, what has affinity with the binder at the time of preparing the composition for transparent film formation, especially organic resin is preferable. In the substrate with a transparent coating obtained by curing the composition for forming a transparent coating on the substrate, the transparent coating is not limited as long as it does not cause whitening of the transparent coating and does not impair the scratch resistance and adhesion. Absent. For example, it may be a hydrocarbon group or a hydrocarbon group containing a carbon atom or a different atom other than a hydrogen atom. The hydrocarbon group may be aliphatic or aromatic, and may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. Further, it may contain a double bond or a triple bond, or may have an ether bond.

  Preferable examples of the organic group directly bonded to the silicon atom include organic groups selected from saturated or unsaturated hydrocarbon groups having 1 to 18 carbon atoms and halogenated hydrocarbon groups having 1 to 18 carbon atoms. it can. Specifically, 3-methacryloxypropyl group, 3-acryloxypropyl group, 3,3,3-trifluoropropyl group, methyl group, phenyl group, isobutyl group, vinyl group, γ-glycidoxytripropyl group, γ-methacryloxypropyl group, N-β (aminoethyl) γ-aminopropyl group, N-β (aminoethyl) γ-aminopropyl group, γ-aminopropyl group, N-phenyl-γ-aminopropyl group, etc. It can be mentioned, but is not limited to these.

<Suitable Aspect of Silica-Based Particle and Organic Group <1 >>
From the viewpoint of adhesion of the transparent coating containing the silica-based particles of the present invention to the base material, prevention of whitening of the coating and scratch resistance, the silica-based particles of the present invention have the following formula (2) or the following formula ( Those having an organic group of 3) and showing a weight loss of 1.5% by mass or more in a temperature range of 200 ° C. to 500 ° C. by thermogravimetry (TG) are preferable.
_{-R-OC (= O) CCH} 3 = CH 2 ··· (2)
(Where R is a divalent hydrocarbon group having 1 to 12 carbon atoms)
-R-OC (= O) CH = CH ₂ (3)
(Where R is a divalent hydrocarbon group having 1 to 12 carbon atoms)

<Preferred embodiment of silica-based hollow particles and organic group <2 >>
For the same reason as described above, the silica-based particles of the present invention preferably have an organic group represented by the following formula (4).
-R-C _n F _a H _b (4)
(Where a + b = 2n + 1, n is an integer of 1 to 3, R is a divalent hydrocarbon group having 1 to 12 carbon atoms)

  The silica-based particles of the present invention are usually dispersed in a dispersion medium. The silica concentration is preferably 1 to 70% by mass from the viewpoint of stability, and more preferably 3 to 40% by mass.

[Transparent coating solution]
The coating liquid for forming a transparent film according to the present invention includes the above-described silica-based particles having an average particle diameter of 5 to 40 nm and a hollow ratio of 70% or more, a matrix-forming component, and a polar solvent.

<Silica-based particles>
The silica-based particles described above are used as the silica-based particles used in the present invention.

<Matrix forming component>
As the matrix forming component, a silicone (sol-gel) matrix forming component, an organic resin matrix forming component, or the like is used.

As the silicone-based matrix-forming component, a hydrolyzed polycondensate of an organosilicon compound similar to the aforementioned formula (1) is preferably used.
Examples of the organic resin matrix forming component include known thermosetting resins, thermoplastic resins, electron beam curable resins, and the like as coating resins.

  Examples of such resins include conventionally used thermoplastic resins such as polyester resins, polycarbonate resins, polyamide resins, polyphenylene oxide resins, thermoplastic acrylic resins, vinyl chloride resins, fluororesins, vinyl acetate resins, and silicone rubbers. , Urethane resin, melamine resin, silicon resin, butyral resin, reactive silicone resin, phenol resin, epoxy resin, unsaturated polyester resin, thermosetting acrylic resin, UV curable acrylic resin, etc., UV curable type An acrylic resin etc. are mentioned. Furthermore, two or more types of copolymers or modified products of these resins may be used. These resins may be emulsion resins, water-soluble resins, and hydrophilic resins. Further, in the case of a thermosetting resin, it may be an ultraviolet curable type or an electron beam curable type, and in the case of a thermosetting resin, a curing catalyst may be included.

<Polymerization initiator, etc.>
When the matrix-forming component is the aforementioned organic resin, a photopolymerization initiator may be included when the resin is an ultraviolet curable resin, and a curing catalyst may be included when the resin is a thermosetting resin. Good. These are not treated as matrix forming components as constituents of the coating solution.

  The polymerization initiator is not particularly limited as long as the matrix forming component can be cured, and conventionally known ones can be used. For example, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) 2,4,4-trimethyl-pentylphosphine oxide, 2-hydroxy-methyl-2-methyl- Phenyl-propane-1-ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-methyl-1- [4- (methylthiophenyl] -2 -Morpholinopropan-1-one and the like.

  Examples of the curing catalyst include inorganic acids such as nitric acid, hydrochloric acid and sulfuric acid, organic acids such as formic acid, acetic acid and itaconic acid, and basic substances such as ammonia, ethylamine and ethanolamine.

<Polar solvent>
The polar solvent used in the present invention is not particularly limited as long as it can dissolve or disperse the matrix-forming component and, if necessary, the polymerization initiator, and uniformly disperse the silica-based hollow particles, and a conventionally known solvent may be used. Can do.

  Specifically, alcohols such as water, methanol, ethanol, propanol, 2-propanol (IPA), butanol, diacetone alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, ethylene glycol, hexylene glycol, isopropyl glycol; acetic acid Esters such as methyl ester, ethyl acetate, butyl acetate; ethers such as diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether Acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, alcohol Ketones such as preparative acetate, methyl cellosolve, ethyl cellosolve, butyl cellosolve, toluene, cyclohexanone, isophorone and the like.

  Among them, alcohols such as methanol, ethanol, propanol, and 2-propanol (IPA) can uniformly disperse surface-treated silica-based fine particles, and a solvent having a carbonyl group can be obtained by treating surface-treated silica-based particles. The paint can be dispersed uniformly and the paint stability is good. For this reason, since the transparent film excellent in uniformity, adhesiveness with a base material, intensity | strength, etc. can be formed with sufficient reproducibility, it can be used conveniently.

  The concentration of the silica-based fine particles in the coating solution for forming a transparent film is preferably in the range of 0.4 to 54 mass%, more preferably 0.6 to 54 mass% as a solid content. When there are few silica type particles in the coating liquid for transparent film formation, there may be a case where a transparent film having a sufficiently low refractive index cannot be obtained because the content of silica type particles in the transparent film is small. On the contrary, even if there are too many silica-based particles, the strength of the transparent film may be insufficient because the content of the matrix-forming component is decreased.

It is preferable that the density | concentration of the matrix formation component in the coating liquid for transparent film formation exists in the range of 0.1-36 mass% as a solid content, and also 0.1-24 mass%.
When the concentration of the matrix-forming component is low, there are few matrix components in the obtained transparent film, and the scratch resistance, adhesion to the substrate, and the like may be insufficient. If the concentration of the matrix-forming component is too high, the content of silica-based particles in the resulting transparent coating is reduced, the refractive index is insufficient, and the antireflection performance may be insufficient.

  In addition, the catalyst for performing reaction, such as superposition | polymerization and a condensation, may be contained in the matrix formation component during application | coating for transparent film formation. Moreover, the component used for a well-known transparent film may be contained.

The total solid content concentration of the coating solution for forming a transparent film is preferably in the range of 1 to 60% by mass, more preferably 3 to 50% by mass.
If the total solid content concentration is lower than 1% by mass, the film thickness of the transparent coating is too thin, and the scratch resistance may be insufficient, and sufficient antireflection performance may not be obtained. . On the other hand, when the total solid content concentration is higher than 60% by mass, the viscosity of the coating solution increases, and the stability of the coating solution decreases or the coating property decreases. Moreover, it is difficult to form a thin film, and the uniformity of the obtained transparent film, adhesion to the substrate, strength, and the like may be insufficient.

As a method for forming a transparent film using the coating liquid for forming a transparent film according to the present invention, a conventionally known method can be employed.
Specifically, the coating liquid for forming a transparent film is formed by a known method such as dipping, spraying, spinner, roll coating, bar coating, slit coater printing, gravure printing, or micro gravure printing. A transparent coating film can be formed by applying to a substrate, drying, and curing by an ordinary method such as ultraviolet irradiation or heat treatment. In the present invention, a roll coating method, a slit coater printing method, a gravure printing method, and a micro gravure printing method are recommended.

[Base material with transparent film]
The substrate with a transparent coating according to the present invention is characterized in that it contains silica particles having an average particle diameter of 5 to 40 nm and a hollow ratio of 70% or more, and a matrix component.

<Base material>
As the substrate used in the present invention, a conventionally known substrate can be used without any particular limitation. Examples include glass, plastic, polycarbonate, acrylic resin, polyethylene terephthalate (PET), triacetyl cellulose (TAC), cyclopolyolefin, norbornene and other plastic sheets, plastic films, and plastic panels.

<Silica-based particles>
As the silica-based particles used in the present invention, the silica-based hollow particles having the aforementioned predetermined average particle diameter and hollow ratio are used.

<Matrix component>
As the matrix component, a silicone (sol-gel) matrix component, an organic resin matrix component, or the like is used.

  The concept of the substrate with a transparent coating of the present invention is schematically shown in FIG. As shown in FIG. 1, when silica-based hollow particles having the above-mentioned predetermined average particle diameter and hollow ratio are used, a homogeneous transparent film is easily obtained, and the adhesion between the substrate and the transparent film is increased. In addition, since the upper surface of the transparent film is smooth with small irregularities, external scattering on the surface can be suppressed. Furthermore, since the particle diameter is small, internal scattering of the coating caused by the particles dispersed in the coating can be suppressed. For this reason, the transparent film is suppressed in whitening, has excellent scratch resistance, magic resistance, water resistance, and alkali resistance, and has a low refractive index and excellent antireflection performance.

  The above-mentioned silica-based particles are silica-based particles having a hollow ratio of 70% or more, and the hollow particles are excellent in transparency and antireflection performance because the inside is composed of only gas or gas and a porous material. . For this reason, it is useful also as a base material with which transparency is requested | required like a display board or a lighting device, for example.

  On the other hand, the concept of a conventional substrate with a transparent coating is schematically shown in FIG. As shown in FIG. 2, the conventional product has a low particle hollowness and a large particle size. Moreover, the unevenness | corrugation of the upper surface of a film is larger than this invention, and the external scattering by the unevenness | corrugation in the film | membrane surface increases from this invention. Furthermore, since the light scattering due to the particle diameter of the particles blended in the coating becomes larger than that of the present invention, the internal scattering of the transparent coating increases. For this reason, the transparent film may be whitened, and scratch resistance, magic resistance, water resistance, and alkali resistance may be reduced. In addition, the desired refractive index and antireflection performance may not be obtained.

  The content of silica-based particles in the transparent coating is preferably in the range of 20 to 80% by mass, more preferably 30 to 70% by mass. The remaining components are matrix components. If the content of the silica particles in the transparent film is less than 20% by mass, a transparent film having a sufficiently low refractive index may not be obtained. On the other hand, when the content of the silica-based particles in the transparent coating exceeds 80% by mass, the content of the matrix component described later is too small, and the strength and scratch resistance of the transparent coating may be insufficient.

The film thickness of the transparent coating is preferably in the range of 80 to 120 nm, more preferably 90 to 110 nm.
If the transparent coating is too thin, the strength and scratch resistance of the membrane may be insufficient. In addition, the film may be too thin to obtain sufficient antireflection performance. Even if the transparent film is too thick, the desired antireflection performance may not be obtained.

  The refractive index of the transparent coating is preferably in the range of 1.15 to 1.40, more preferably 1.20 to 1.35. If the refractive index of the transparent coating is lower than the above range, it is difficult to obtain from the viewpoint of coating composition, and if the refractive index increases, the refractive index of the substrate or the lower layer of the transparent coating formed as necessary Depending on the refractive index of the other film formed, the antireflection performance may be insufficient.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

[Example 1]
<Preparation of silica-based particles (1)>
After adding 946.4 g of pure water to 53.6 g of an aqueous dispersion of seed particles (manufactured by JGC Catalysts & Chemicals, Inc .: SI-550, SiO ₂ concentration 20.5% by mass), 1% by mass of sodium hydroxide was added. The pH was adjusted to 11.0 by addition. Then, it heated at 60 degreeC and hold | maintained for about 30 minutes, and obtained the aqueous dispersion of the core particle (1). The core particles (1) had an average particle size of 5 nm and a sphericity of 1.1.
While maintaining the aqueous dispersion of the core particles (1) at 60 ° C., 28.6 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 0.25% by mass of sodium aluminate as an Al ₂ O ₃ 28.6 kg of an aqueous solution was added over 16 hours to obtain a primary particle dispersion of composite oxide (SiO ₂ · Al ₂ O ₃ ). The pH of the reaction solution at this time was 11.1. Moreover, the average particle diameter was 15 nm.
Next, 129.4 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 43.12 kg of a sodium silicate aqueous solution having a concentration of 0.25% by mass as Al ₂ O ₃ were added over 8 hours to coat the composite oxide. A dispersion of particles was obtained. At this time, the pH of the reaction solution was 11.0.
Subsequently, after washing with an ultrafiltration membrane to a solid content concentration of 13% by mass, the mixture was filtered through a capsule filter having an opening of 1 μm to obtain a coated composite oxide particle (1) dispersion. At this time, the average particle diameter was 22 nm.
1,500 g of pure water was added to 500 g of the dispersion of the coated composite oxide particles (1), and concentrated hydrochloric acid (concentration 35.5% by mass) was added dropwise to adjust the pH to 1.0, followed by dealumination. Next, an aqueous dispersion of silica-based particles (1-1) having a solid content concentration of 20 mass% is obtained by separating and washing the aluminum salt dissolved in the ultrafiltration membrane while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water. It was.
Next, aqueous ammonia is added to the dispersion of silica-based particles (1-1) to adjust the pH of the dispersion to 10.5, and after aging at 80 ° C. for 11 hours, the solution is cooled to room temperature, and cation Ion exchange using 400 g of exchange resin (Mitsubishi Chemical Corporation: Diaion SK1B) for 3 hours, followed by ion exchange for 3 hours using 200 g of anion exchange resin (Mitsubishi Chemical Corporation: Diaion SA20A) Further, 200 g of a cation exchange resin (Mitsubishi Chemical Co., Ltd .: Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain silica-based particles (1-2) An aqueous dispersion was obtained.
Next, an alcohol dispersion of silica-based particles (1-2) having a solid content concentration of 20% by mass in which the solvent was replaced with ethanol using an ultrafiltration membrane was prepared.
6 g of 3-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-503) is added to 100 g of an alcohol dispersion of silica-based particles (1-2) having a solid content concentration of 20% by mass, and at 50 ° C. An alcohol dispersion of silica-based particles (1) having a solid content concentration of 20% by mass was prepared by performing a heat treatment for 36 hours and replacing the solvent with ethanol again using an ultrafiltration membrane.
It shows in Table 1 about each preparation process of this silica type particle | grain (1). Table 2 shows the physical properties of the average particle diameter, hollowness, sphericity, number ratio of irregularly shaped particles, refractive index and porosity of the silica-based particles (1). Each measurement was performed by the method shown in “Mode for Carrying Out the Invention”.

<Manufacture of paint (1) for forming an antireflection transparent coating>
50 g of a dispersion obtained by diluting an alcohol dispersion of silica-based particles (1) with ethanol to a solid content concentration of 5% by mass, 1.67 g of acrylic resin (Hitaroid 1007, manufactured by Hitachi Chemical Co., Ltd.) and isopropanol and n-butanol A paint (1) for forming a transparent film was prepared by thoroughly mixing 52.6 g of a 1/1 (mass ratio) mixed solvent. This transparent film-forming paint (1) is shown in Table 3.

<Preparation of coating solution for forming hard coat film>
Silica sol dispersion (manufactured by JGC Catalysts &Chemicals; Cataloid SI-30; average particle size 12 nm, SiO ₂ concentration 40.5% by mass, dispersion medium: isopropanol, particle refractive index 1.46) to 100 g of γ-meta 1.88 g of acryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-503, SiO ₂ concentration 81.2 mass%) was mixed, 3.1 g of ultrapure water was added, and the mixture was stirred at 50 ° C. for 20 hours. Thus, a surface-treated 12 nm silica sol dispersion was obtained (solid content concentration 40.5% by mass).
Thereafter, the solvent was replaced with propylene glycol monopropyl ether (PGME) by a rotary evaporator (solid content concentration: 40.5% by mass).
Next, 51.85 g of this silica sol propylene glycol monopropyl ether dispersion having a solid content concentration of 40.5% by mass, 18.90 g of dihexaerythritol triacetate (manufactured by Kyoeisha Chemical Co., Ltd .: DPE-6A), and 1.6 -Hexanediol diacrylate (manufactured by Kyoeisha Chemical Co., Ltd .; light acrylate SR-238F) 2.10 g, silicone leveling agent (manufactured by Enomoto Kasei Co., Ltd .; Disparon 1610) and photopolymerization initiator (Ciba Japan ( Co., Ltd .: Irgacure 184, dissolved to a solid content of 10% by mass with PGME) 12.60 g and 14.54 g of PGME were sufficiently mixed to prepare a coating solution for forming a hard coat film having a solid content of 42.0% by mass. .

<Manufacture of substrate (1) with transparent coating for antireflection>
The hard coat film forming coating solution was applied to a TAC film (manufactured by Panac Corporation: FT-PB80UL-M, thickness: 80 μm, refractive index: 1.51) by the bar coater method (# 18), and 80 ° C. And dried for 120 seconds, and then cured by irradiating with 300 mJ / cm ² of ultraviolet rays to form a hard coat film. The film thickness of the hard coat film was 8 μm.
Next, the coating solution (1) for forming an antireflection transparent coating was applied by the bar coater method (# 4), dried at 80 ° C. for 120 seconds, and then irradiated with 600 mJ / cm ² of ultraviolet rays in an N ₂ atmosphere. Cured to prepare a substrate (1) with a transparent coating for antireflection. At this time, the film thickness of the antireflection transparent coating was 100 nm. Total light transmittance, haze, reflectance of light having a wavelength of 550 nm, coating refractive index, adhesion and pencil hardness, scratch resistance, whitening, magic resistance, water resistance of the substrate (1) with a transparent coating for antireflection Table 4 shows the evaluation results on the properties and alkali resistance. The total light transmittance and haze were measured with a haze meter (manufactured by Suga Test Instruments Co., Ltd.), and the reflectance was measured with a spectrophotometer (JASCO Corporation, Ubest-55). Moreover, the refractive index of the film was measured with an ellipsometer (manufactured by ULVAC, EMS-1).

《Adhesion》
When the surface of the substrate (1) with a transparent coating is made with 100 knives by making 11 parallel scratches with a knife at intervals of 1 mm in length and width, cellophane tape is adhered to this, and then the cellophane tape is peeled off The adhesion was evaluated by classifying the number of cells remaining without peeling off the coating into the following three stages. The results are shown in the table.
Number of remaining squares more than 90: ◎
Number of remaining squares: 85 to 89: ○
Number of remaining squares: 84 or less: △

"Pencil hardness"
The pencil hardness was measured with a pencil hardness tester according to JIS K 5400. That is, a pencil was set at an angle of 45 degrees with respect to the transparent coating surface, and a predetermined load was applied and pulled at a constant speed, and the presence or absence of scratches was observed.

<Measurement of scratch resistance>
Using # 0000 steel wool, sliding 50 times with a load of 1,000 g / cm ² , visually observing the surface of the film, and evaluating according to the following criteria, the results are shown in the table.
Evaluation criteria:
No streak is found: ◎
Slight streak is observed: ○
Many streak wounds are found: △
The surface has been cut entirely: ×

<Evaluation of whitening>
The surface of the coating film was visually observed from an oblique direction (about 20 °), and the evaluation was evaluated in the following four stages.
Evaluation criteria:
No whitening is recognized: ◎
There is some whitening: ○
Partly whitened: △
Fully whitened: ×

<Evaluation of magic resistance>
Draw a line with a length of 3 cm with oily magic on the surface of the paint film, leave it for 1 minute, and visually check the trace when wiped off.
Evaluation criteria:
I can't see the magic mark: ◎
I can hardly see the magic mark: ○
Some of the magic marks are visible: △
The magic mark is visible on the entire surface: ×

<< Evaluation of water resistance >>
Drop a drop of pure water on the surface of the coating film with a dropper, and after leaving it for 3 hours, wipe off the water droplets and visually check if there are any traces where the water droplets were present.
Evaluation criteria:
No trace of water drops: ○
Some traces of water droplets are observed:
Water traces can be clearly seen: ×

<< Evaluation of alkali resistance >>
A drop of 1% NaOH aqueous solution is dropped on the surface of the coating film, and after standing for 1 hour, the water droplets are wiped off, and it is visually confirmed whether traces remain where the water droplets were present.
Evaluation criteria:
No trace is recognized: ○
Some traces are recognized:
Marks can be clearly seen: ×

[Example 2]
<Preparation of silica-based particles (2)>
300 g of a cation exchange resin (manufactured by Mitsubishi Chemical Corporation: Diaion SK1B) was added to 1000 g of an aqueous sodium silicate solution having a concentration of 3.5% by mass as SiO _{2 and} stirred at room temperature for 1 hour, and then the ion exchange resin was separated. An aqueous silicic acid solution was obtained. Next, 4.2 g of silicic acid aqueous solution, 62.5 g of pure water, and 13.1 g of sodium silicate were mixed, aged at 70 ° C. for 1 hour, and then kept at 70 ° C., 141.4 g of silicic acid aqueous solution was taken over 6 hours. By addition, seed particles (2) having an average particle diameter of 3 nm were obtained. 1.1% by weight of seed particles (2) 1% by weight of sodium hydroxide was added to 1.0 kg of the aqueous dispersion to adjust the pH to 11.0. Then, it heated at 60 degreeC and hold | maintained for about 30 minutes, and obtained the aqueous dispersion of a core particle (2). The average particle diameter of the core particles (2) was 3 nm, and the sphericity was 1.2.
While maintaining the aqueous dispersion of the core particles (2) at 60 ° C., 4.0 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 0.25% by mass of sodium aluminate as an Al ₂ O ₃ 4.0 kg of an aqueous solution was added over 18 hours to obtain a primary particle dispersion of a composite oxide (SiO ₂ · Al ₂ O ₃ ). The pH of the reaction solution at this time was 11.0. Moreover, the average particle diameter was 5 nm.
Subsequently, 78.4 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 26.1 kg of a sodium aluminate aqueous solution having a concentration of 0.25% by mass as Al ₂ O ₃ were added over 8 hours to coat the composite oxide. A dispersion of particles was obtained. At this time, the pH of the reaction solution was 11.0.
Subsequently, after washing with an ultrafiltration membrane to a solid content concentration of 13% by mass, the mixture was filtered through a capsule filter having an opening of 1 μm to obtain a coated composite oxide particle (2) dispersion. At this time, the average particle diameter was 12 nm.
Thereafter, silica-based particles (2) were obtained in the same manner as in Example 1 except that the coated composite oxide particles (2) were used.
A transparent film-forming paint (2) and an antireflection transparent film-coated substrate (2) were prepared in the same manner as in Example 1 except that the silica-based particles (2) were used.

[Example 3]
<Preparation of silica-based particles (3)>
After adding 963.9 g of pure water to 36.1 g of an aqueous dispersion of seed particles (manufactured by JGC Catalysts & Chemicals Co., Ltd .: SI-30, SiO ₂ concentration 30.5 mass%), 1 mass% sodium hydroxide was added. The pH was adjusted to 11.0 by addition. Then, it heated at 60 degreeC and hold | maintained for about 30 minutes, and obtained the aqueous dispersion of a core particle (3). The average particle diameter of the core particles (3) was 12 nm, and the sphericity was 1.0.
While maintaining the aqueous dispersion of the core particles (3) at 60 ° C., 7.7 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 0.25% by mass of sodium aluminate as an Al ₂ O ₃ 7.7 kg of an aqueous solution was added over 18 hours to obtain a primary particle dispersion of a composite oxide (SiO ₂ · Al ₂ O ₃ ). The pH of the reaction solution at this time was 11.2. The average particle size was 24 nm.
Subsequently, 38.3 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 12.8 kg of a sodium oxalate aqueous solution having a concentration of 0.25% by mass as Al ₂ O ₃ were added over 8 hours to coat the composite oxide. A dispersion of particles was obtained. At this time, the pH of the reaction solution was 11.0.
Subsequently, after washing with an ultrafiltration membrane to a solid content concentration of 13% by mass, the mixture was filtered through a capsule filter having an opening of 1 μm to obtain a coated composite oxide particle (3) dispersion. At this time, the average particle diameter was 12 nm.
Thereafter, silica-based particles (3) were obtained in the same manner as in Example 1 except that the coated composite oxide particles (3) were used.
A transparent film-forming paint (3) and an antireflection transparent film-coated substrate (3) were produced in the same manner as in Example 1 except that the silica-based particles (3) were used.

[Example 4]
<Preparation of silica-based particles (4)>
After adding 946.4 g of pure water to 53.6 g of an aqueous dispersion of seed particles (manufactured by JGC Catalysts & Chemicals, Inc .: SI-550, SiO ₂ concentration 20.5% by mass), 1% by mass of sodium hydroxide was added. The pH was adjusted to 11.0 by addition. Then, it heated at 60 degreeC and hold | maintained for about 30 minutes, and obtained the aqueous dispersion of a core particle (4). The core particles (4) had an average particle size of 5 nm and a sphericity of 1.0.
While maintaining the aqueous dispersion of the core particles (4) at 60 ° C., 28.6 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 0.25% by mass of sodium aluminate as Al ₂ O ₃ 28.6 kg of an aqueous solution was added over 18 hours to obtain a primary particle dispersion of composite oxide (SiO ₂ · Al ₂ O ₃ ). The pH of the reaction solution at this time was 11.2. Moreover, the average particle diameter was 15 nm.
Then, 141.6 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 75.0 kg of an aqueous solution of sodium aluminate having a concentration of 0.25% by mass as Al ₂ O ₃ were added over 8 hours to coat the composite oxide. A dispersion of particles was obtained. At this time, the pH of the reaction solution was 11.0.
Subsequently, after washing with an ultrafiltration membrane to a solid content concentration of 13% by mass, the mixture was filtered through a capsule filter having an opening of 1 μm to obtain a coated composite oxide particle (4) dispersion. At this time, the average particle diameter was 26 nm.
Thereafter, silica-based particles (4) were obtained in the same manner as in Example 1 except that the coated composite oxide particles (4) were used.
A transparent film-forming paint (4) and a substrate with antireflection transparent film (4) were produced in the same manner as in Example 1 except that the silica-based particles (4) were used.

[Example 5]
<Preparation of silica-based particles (5)>
After adding 946.4 g of pure water to 53.6 g of an aqueous dispersion of seed particles (manufactured by JGC Catalysts & Chemicals, Inc .: SI-550, SiO ₂ concentration 20.5% by mass), 1% by mass of sodium hydroxide was added. The pH was adjusted to 11.0 by addition. Then, it heated at 80 degreeC and hold | maintained for about 30 minutes, and obtained the aqueous dispersion of a core particle (5). The core particles (5) had an average particle diameter of 5 nm and a sphericity of 1.4.
Silica-based particles (5) were obtained in the same manner as in Example 1 except that the core particles (5) were used.
A transparent film-forming paint (5) and an antireflection transparent-coated substrate (4) were produced in the same manner as in Example 1 except that the silica-based particles (5) were used.

[Example 6]
<Preparation of silica-based particles (6)>
After adding 946.4 g of pure water to 53.6 g of an aqueous dispersion of seed particles (manufactured by JGC Catalysts & Chemicals, Inc .: SI-550, SiO ₂ concentration 20.5% by mass), 1% by mass of sodium hydroxide was added. The pH was adjusted to 11.0 by addition. Then, it heated at 60 degreeC and hold | maintained for about 30 minutes, and obtained the aqueous dispersion liquid of a core particle (6). The core particles (6) had an average particle size of 5 nm and a sphericity of 1.0.
While maintaining the aqueous dispersion of the core particles (6) at 60 ° C., 5.3 kg of sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 0.25% by mass of aluminate as Al ₂ O ₃ 5.3 kg of an aqueous sodium solution was added over 18 hours to obtain a primary particle dispersion of a composite oxide (SiO ₂ · Al ₂ O ₃ ). The pH of the reaction solution at this time was 11.2. Moreover, the average particle diameter was 9 nm.
Next, 148.6 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 78.7 kg of a sodium silicate aqueous solution having a concentration of 0.25% by mass as Al ₂ O ₃ were added over 8 hours to coat the composite oxide. A dispersion of particles was obtained. At this time, the pH of the reaction solution was 11.0.
Subsequently, after washing with an ultrafiltration membrane to obtain a solid content concentration of 13% by mass, the mixture was filtered through a capsule filter having an opening of 1 μm to obtain a coated composite oxide particle (6) dispersion. At this time, the average particle diameter was 26 nm.
Thereafter, silica-based particles (6) were obtained in the same manner as in Example 1 except that the coated composite oxide particles (6) were used.
A transparent film-forming paint (6) and an antireflection transparent film-coated substrate (6) were prepared in the same manner as in Example 1 except that the silica-based particles (6) were used.

[Example 7]
<Preparation of silica-based particles (7)>
After adding 946.4 g of pure water to 53.6 g of an aqueous dispersion of seed particles (manufactured by JGC Catalysts & Chemicals, Inc .: SI-550, SiO ₂ concentration 20.5% by mass), 1% by mass of sodium hydroxide was added. The pH was adjusted to 11.0 by addition. Then, it heated at 60 degreeC and hold | maintained for about 30 minutes, and obtained the aqueous dispersion liquid of a core particle (7). The core particles (7) had an average particle size of 5 nm and a sphericity of 1.0.
While maintaining an aqueous dispersion of the core particles (7) at 60 ° C., 236.5 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 0.25% by mass of sodium aluminate as an Al ₂ O ₃ 236.5 kg of an aqueous solution was added over 18 hours to obtain a primary particle dispersion of composite oxide (SiO ₂ · Al ₂ O ₃ ). The pH of the reaction solution at this time was 11.2. Moreover, the average particle diameter was 30 nm.
Subsequently, 369.0 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 195.4 kg of a sodium silicate aqueous solution having a concentration of 0.25% by mass as Al ₂ O ₃ were added over 8 hours to coat the composite oxide. A dispersion of particles was obtained. At this time, the pH of the reaction solution was 11.4.
Subsequently, after washing with an ultrafiltration membrane to obtain a solid content concentration of 13% by mass, the mixture was filtered through a capsule filter having an opening of 1 μm to obtain a coated composite oxide particle (7) dispersion. At this time, the average particle diameter was 40 nm.
Thereafter, silica-based particles (7) were obtained in the same manner as in Example 1 except that the coated composite oxide particles (7) were used.
A transparent film-forming paint (7) and an antireflection transparent film-coated substrate (7) were produced in the same manner as in Example 1 except that the silica-based particles (7) were used.

[Example 8]
<Preparation of silica-based particles (8)>
After adding 963.9 g of pure water to 36.1 g of an aqueous dispersion of seed particles (manufactured by JGC Catalysts & Chemicals Co., Ltd .: SI-30, SiO ₂ concentration 30.5 mass%), 1 mass% sodium hydroxide was added. The pH was adjusted to 12.5 by adding. Then, it heated at 95 degreeC and hold | maintained for about 30 minutes, and obtained the aqueous dispersion liquid of a core particle (8). The average particle diameter of the core particles (8) was 12 nm, and the sphericity was 1.3.
Thereafter, silica-based particles (8) were obtained in the same manner as in Example 3 except that the core particles (8) were used.
A transparent film-forming paint (8) and an antireflection transparent film-coated substrate (8) were prepared in the same manner as in Example 1 except that the silica-based particles (8) were used.

[Comparative Example 1]
<Preparation of silica-based particles (R1)>
After adding 946.4 g of pure water to 53.6 g of an aqueous dispersion of seed particles (manufactured by JGC Catalysts & Chemicals, Inc .: SI-550, SiO ₂ concentration 20.5% by mass), 1% by mass of sodium hydroxide was added. The pH was adjusted to 12.5 by adding. Then, it heated at 95 degreeC and hold | maintained for about 30 minutes, and obtained the aqueous dispersion of a core particle (R1). The average particle diameter of the core particles (R1) was 5 nm, and the sphericity was 1.8.
Silica-based particles (R1) were obtained in the same manner as in Example 1 except that the core particles (R1) were used.
A transparent film-forming paint (R1) and an antireflection transparent-coated substrate (R1) were prepared in the same manner as in Example 1 except that the silica-based particles (R1) were used.

[Reference Example 1]
<Preparation of silica-based particles (E1)>
After adding 946.4 g of pure water to 53.6 g of an aqueous dispersion of seed particles (manufactured by JGC Catalysts & Chemicals, Inc .: SI-550, SiO ₂ concentration 20.5% by mass), 1% by mass of sodium hydroxide was added. The pH was adjusted to 11.0 by addition. Then, it heated at 60 degreeC and hold | maintained for about 30 minutes, and obtained the aqueous dispersion of the core particle (E1). The average particle diameter of the core particles (E1) was 5 nm, and the sphericity was 1.0.
While maintaining an aqueous dispersion of core particles (E1) at 60 ° C., 562.1 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 0.25% by mass of sodium aluminate as an Al ₂ O ₃ 562.1 kg of an aqueous solution was added over 18 hours to obtain a primary particle dispersion of a composite oxide (SiO ₂ · Al ₂ O ₃ ). The pH of the reaction solution at this time was 11.2. Moreover, the average particle diameter was 40 nm.
Subsequently, 1021.0 kg of a sodium silicate aqueous solution having a concentration of 0.75% by mass as SiO ₂ and 540.5 kg of a sodium silicate aqueous solution having a concentration of 0.25% by mass as Al ₂ O ₃ were added over 8 hours to coat the composite oxide. A dispersion of particles was obtained. At this time, the pH of the reaction solution was 11.5.
Subsequently, after washing with an ultrafiltration membrane to obtain a solid content concentration of 13% by mass, the mixture was filtered through a capsule filter having an opening of 1 μm to obtain a coated composite oxide particle (E1) dispersion. At this time, the average particle diameter was 40 nm.
Thereafter, silica-based particles (E1) were obtained in the same manner as in Example 1 except that the coated composite oxide particles (E1) were used.
A transparent film-forming paint (E1) and an antireflection transparent-coated substrate (E1) were produced in the same manner as in Example 1 except that the silica-based particles (E1) were used.

Claims (13)

This is a method for producing a dispersion of silica-based particles having an average particle diameter of 5 to 40 nm and a ratio of the number of hollow particles to the total number of hollow particles and solid particles (hollow ratio) of 70% or more. And
In a dispersion containing silica core particles having an average particle size of 3 to 25 nm and a sphericity of 1.0 to 1.5, at least one of a silicate aqueous solution and an acidic silicate solution, and an inorganic compound aqueous solution not containing silicon Are added simultaneously to prepare a dispersion containing composite oxide particles,
A second step of preparing a dispersion containing coated composite oxide particles coated with a layer containing silica by adding a silica source to the dispersion containing the composite oxide particles obtained in the first step;
A third step of adding an acid to the dispersion containing the coated composite oxide particles obtained in the second step to remove an element derived from the inorganic compound contained in the coated composite oxide particles;
A fourth step of hydrothermally treating the dispersion containing the particles obtained in the third step under alkaline conditions;
A method for producing a silica-based particle dispersion, comprising:   In the first step, the dispersion containing the composite oxide particles is prepared at a solid content concentration of 0.1 to 0.9% by mass, and the particle growth rate from the core particles to the composite oxide particles is 0.1 to 10 nm. The method for producing a silica-based particle dispersion according to claim 1, wherein the method is performed at a time per hour.   3. The method for producing a silica-based particle dispersion according to claim 1, wherein the composite oxide particles have an average particle diameter of 3 to 35 nm and a sphericity of 1.0 to 1.5. In the first step, the silica derived from the silicate aqueous solution and the acidic silicate solution is represented by SiO ₂ , and the molar ratio MO _X / SiO ₂ when the inorganic compound derived from the inorganic compound aqueous solution is represented by MO _X as an oxide is It is 0.15-3.0, The manufacturing method of the silica type particle dispersion liquid in any one of Claims 1-3 characterized by the above-mentioned.   The at least one of a silicate aqueous solution and an acidic silicate solution and an inorganic compound aqueous solution not containing silicon are added in the second step to form a coating layer containing silica on the composite oxide particles. The manufacturing method of the dispersion liquid of the silica type particle in any one of 1-4.   In the second step, the formation of the coating layer containing silica on the composite oxide particles is performed at a solid content concentration of 0.1 to 0.9% by mass, and the formation rate of the coating layer on the composite oxide particles is 0.1. The method for producing a dispersion of silica-based particles according to any one of claims 1 to 5, wherein the method is performed at 10 to 10 nm / hour.   Silica-based particles containing silica-based particles having an average particle diameter of 5 to 40 nm and a ratio of the number of hollow particles to the total number of hollow particles and solid particles (hollow ratio) of 70% or more Particle dispersion.   The dispersion of silica-based particles according to claim 7, wherein the sphericity of the silica-based particles is 1.0 to 1.5.   The silica particle dispersion according to claim 7 or 8, wherein the silica particles have a porosity of 3 to 50%.   The silica-based particle dispersion according to claim 7, wherein the silica-based particle has an organic group directly bonded to a silicon atom on a surface thereof.   A coating liquid for forming a transparent film, comprising the silica-based particles according to claim 7, a matrix-forming component, and a polar solvent. The concentration of the silica-based particles is 0.4 to 54% by mass as a solid content,
The concentration of the matrix-forming component is 0.1 to 36% by mass;
The coating liquid for forming a transparent film according to claim 11, wherein the total solid content concentration is 1 to 60% by mass. A substrate with a transparent coating comprising a substrate and a transparent coating comprising the silica-based particles and the matrix component according to any one of claims 7 to 10 formed on the substrate,
Content of the silica-type particle in the said transparent film is 20-80 mass%, The base material with a transparent film characterized by the above-mentioned.