JP7185831B2 - Silica particles having a net-like outer shell and inner space, and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to silica-based particles having a net-like outer shell and an inner space, and having through-holes leading from the inner space to the outer shell. When the silica particles of the present invention are used as a filler, the silica particles of the present invention have through-holes so that the resin matrix or the like can be easily immersed therein, the particles are less likely to fall off, and the transparency is not impaired. In addition, since the porosity is high, when added to a film or coating, even a small amount of addition can exhibit effects such as slip properties and anti-blocking properties.

Conventionally, porous particles are produced having pores on the particle surface. Porous particles have been used as catalysts, adsorbents, etc. by utilizing their pores.
For example, Patent Document 1 discloses hollow particles having 5 to 100 macropores with a pore size of 60 nm to 10 μm in a silica shell portion and a particle size of 0.2 to 100 μm (Patent Document 1 ).
In Patent Document 2, interparticle voids are formed inside aggregates of spherical silica fine particles having an average particle size of 10 to 50 nm, a sphericity range of 0.9 to 1, and a particle size variation coefficient (CV value) of 2 to 10%. Structured porous silica particles having an average particle diameter (PD) of 0.5 to 50 μm, a specific surface area of 30 to 250 m ² /g, and a pore volume of 0.10 to 0.1 μm. Porous silica in the range of 25 cc/g is disclosed.

In Patent Document 3, the ratio D ₁ /D ₂ of the particle diameter (D ₁ ) measured by the dynamic light scattering method and the particle diameter (D ₂ ) measured by the nitrogen gas adsorption method is 4 to 10, and D ₁ is It has an average particle size of 0.1 to 1.0 μm measured by a laser diffraction method, which is obtained by aggregating elongated colloidal silica having a diameter of 40 to 200 nm and a _D2 of 8 to 30 nm, and is measured by a nitrogen gas adsorption method. A secondary aggregated porous silica sol having a specific surface area of 90-350 m ² /g and a mesopore volume of 0.5-2.0 cm ³ /g is disclosed.

In Patent Document 4, the hard coat film is composed of metal oxide fine particles treated with a surfactant and a hydrophobic matrix component, and the average particle diameter of the metal fine particles treated with the surfactant is in the range of 30 to 150 nm. and the height of the protrusions on the hard coat film is in the range of 10 to 200 nm, and the surfactant treatment amount in the metal fine particles is in the range of 2 to 30% by mass with respect to the fine particles, A substrate with a hard coat film is disclosed in which the content of the surfactant-treated fine metal particles in the hard coat film is in the range of 0.01 to 20% by mass. It is disclosed that the metal oxide fine particles here are silica sol having an average particle size of 30 to 150 nm as measured by electron microscopic observation, and the surfactant is an anionic surfactant such as an alkyl ether phosphate. there is

JP 2007-230794 JP 2010-138021 JP 2013-091589 JP 2013-136222

Although conventional porous silica particles have pores on the particle surface, the pore volume is not sufficiently large and they have independent pores.

The present invention is not a porous silica particle based on pores existing on the surface, but a silica particle in which the pores form through holes through the internal space, and as a result, has a net-like outer shell and internal space, and an internal It is a particle whose main component is silica and has through holes that lead from the space to the outer shell. Since the silica particles have internal spaces and through-holes, the silica particles are so-called frame-shaped silica particles having a net-like outer shell and internal spaces containing silica as a main component. To provide silica particles capable of containing various components and media inside the space by utilizing the space (cavity).

As a first aspect of the present invention, particles having a net-like outer shell and an inner space, and having through-holes connecting the inner space to the outer shell, the particles mainly composed of silica, wherein the diameter of the net is 20 nm to 90 nm, and silica particles having a porosity of 30 to 90% and an average particle diameter (A ₂ ) of 100 nm to 1.5 μm as measured by a laser diffraction method;
As a second aspect, the average primary particle size (A ₁ ) observed with a transmission electron microscope is 100 nm to 1.5 μm, and the ratio of the average particle size (A ₂ )/average primary particle size (A ₁ ) is 0. .8 to 1.5 silica particles according to the first aspect,
As a third aspect, the silica particles according to the first aspect or the second aspect, which have a specific surface area of 20 to 90 m ² /g as measured by a nitrogen gas adsorption method;
As a fourth aspect, the silica particles according to any one of the first to third aspects are dispersed in an acidic or alkaline aqueous medium or organic solvent, and the average particle diameter (A ₂ ) is between 100 nm and 1.5 μm,
As a fifth aspect, the method for producing a silica sol according to the fourth aspect including the following steps (a) to (b),
(a) step: the ratio D ₁ /D ₂ of the particle diameter (D ₁ ) measured by the dynamic light scattering method and the particle diameter (D ₂ ) measured by the nitrogen gas adsorption method is 4 to 10, and D ₁ is 40 ~ 200 nm, D ₂ of 8-30 nm, colloidal silica with a SiO ₂ concentration of 21-30 wt. a step of producing an alkaline porous secondary aggregate silica aqueous sol having an average particle size of 100 nm to 1.5 μm and a specific surface area of 90 to 350 m ² /g as measured by a nitrogen gas adsorption method;
(b) step: SiO ₂ /Na ₂ O molar ratio of 30 to 3000, SiO ₂ concentration of 0.1 to 30% by mass, pH adjusted to 3 to 11, and then at a temperature above 100° C. and below 270° C. a step of hydrothermally treating for 1 to 30 hours;
As a sixth aspect, after the step (b) described in the fifth aspect, a method for producing an organosilica sol, wherein the step of replacing the aqueous medium with an organic solvent is performed.
As a seventh aspect, a film-forming composition comprising the silica particles according to any one of the first to fourth aspects and a resin,
As an eighth aspect, the film-forming composition according to the seventh aspect, wherein the resin is a photocurable resin or a thermosetting resin, and as a ninth aspect, from the film-forming composition according to the seventh aspect or the eighth aspect This is the film formed.

The present invention is a particle composed mainly of silica having a net-like outer shell and an inner space, and having through-holes connecting the inner space to the outer shell.

The conventional pores that exist only on the surface are independent pores, and the fine cavities inside the pores are used to perform catalytic action and adsorption action, and sufficient pore volume could not be used. .

In the present invention, slender silica particles are used as a starting material, the slender silica particles are stirred under high shearing force to form aggregated particles, and the aggregated particles are subjected to autoclave treatment under hydrothermal conditions to form reticulated silica. It was found that the silica particles of the present invention were formed as silica particles with a specific shape that only remained as a skeleton.

Since the silica particles of the present invention have internal spaces and through-holes, they are frame-shaped silica particles having large spaces (cavities) formed by a network-like skeleton containing silica as a main component. Since the reticulated silica is formed on the outer shell of the particle surface, it becomes spherical and forms the particle, so the hole is a through hole that penetrates the particle. It can be expressed as a so-called frame-shaped silica particle by forming through-holes leading from the space to the outer shell (particle surface).

Since the through-hole is a hole that penetrates one silica particle from the front surface to the back surface through the internal space, the through-hole allows gas or liquid to move freely. The through-hole and the internal space can store gas or liquid in the hole, or allow gas or liquid to pass through. Such unique properties are not found in conventional porous particles or solid particles (particles without pores).

The silica particles of the present invention utilize the above-described properties, and when a hard coat film is formed as a film-forming composition, the binder component in the film-forming composition penetrates into the silica particles, improving the integrity of the particles and the binder. Also, the silica component can be sufficiently blended into the coating film. This improves the transparency of the coating film. Furthermore, it tends to exhibit its function as silica in the coating film, leading to improved antiblocking performance and improved coating film hardness.

In addition, it is possible to provide a coating film with a component difference and a concentration difference between the inside and outside of the particle by utilizing the function of storing inside the particle.

Transmission electron micrograph of porous secondary aggregated silica particles α-1. Transmission electron micrograph of silica particles α-2 having a reticulated shell. Transmission electron micrograph of porous secondary aggregated silica particles β-1. Transmission electron micrograph of silica particles β-2 having a reticulated shell. A transmission electron micrograph of β-3 in which silica particles having reticulated shells and silica particles having no reticulated shells are mixed. A transmission electron micrograph of β-4 in which silica particles having a net-like shell and silica particles in which the net is cut are mixed. Transmission electron micrograph of porous secondary aggregated silica particles γ-1. A transmission electron micrograph of silica particles γ-2 having a reticulated shell. Transmission electron micrograph of spherical solid silica particles δ-1. Transmission electron micrograph of spherical solid silica particles δ-2. An electron micrograph obtained by photocuring a photocurable resin containing silica particles β-2 having a net-like shell, cutting a cross section of the cured resin, and observing the cross section.

The present invention is a particle mainly composed of silica having a net-like outer shell and an inner space, and having through-holes connecting the inner space to the outer shell, the diameter of the net being 20 nm to 90 nm, and voids in the particle. It is a silica particle having a ratio of 30 to 90% and an average particle size (A ₂ ) of 100 nm to 1.5 μm as measured by a laser diffraction method.

A silica sol in which the silica particles are dispersed in an aqueous medium or an organic solvent. These silica sols are obtained with a silica concentration in the range of 0.1 to 50% by mass.

The average particle size (A ₂ ) of silica particles can be measured using a laser diffraction particle size measuring device (for example, SALD (registered trademark)-7500 manufactured by Shimadzu Corporation). In the present invention, it can be manufactured in the range of 100 nm to 1.5 μm.
In the silica particles of the present invention, the area ratio of the projected through-holes in the projected particles is 2 to 30% as measured from the plane projection view by observation with a transmission electron microscope. Using transmission electron microscopy (hereinafter referred to as TEM) observation, the projected through-holes present in the projected particles are 2 to 30%, or 3 to 20%, or 3 to 10% from the plan view. is. This ratio can be measured by using an image analyzer for a transmission electron microscope image.
In silica particles, the diameter of the network formed by the silica component is the particle diameter calculated from the specific surface area, assuming that the silica particles forming the network are infinitely elongated silica particles that are three-dimensionally rounded. can ask. The specific surface area can be measured using a nitrogen gas adsorption specific surface area measuring device (for example, Monosorb manufactured by Quantachrome).
That is, if the volume is V ₁ (m ³ ), the density is ρ (kg/m ³ ), and the surface area is S (m ² ), the specific surface area per unit mass is Sw=S/ρV.

Assuming silica to be an infinitely long cylinder, the surface area S(m ² ) can be obtained by S=2πr(r+h). where π is the circular constant, r(m) is the radius of the end face of the cylinder, V ₁ is the volume, and V ₁ =πr ² h. h(m) is the length of the cylinder. From Sw=S/ _ρV1 ,
Sw=(2πr(r+h))/ρπr ² h=2πr ² /ρπr ² h+2πrh/ρπr ² h
becomes. By the way, assuming an infinitely long cylinder, h = infinity, so
Sw = 2/ρr, and when silica particle radius r (nm) is converted to silica particle diameter d (nm), Sw = 4/(ρ × 10 ⁶ ) × (d × 10 ^-9 ) to Sw = 4000/ρd becomes. This is defined as formula (1).
Also, since the density of amorphous silica is ρ=2.2 g/cm ³ , d(nm)=1820/Sw is calculated. This formula can be measured as the diameter (nm) of the mesh.

In addition, the porosity in the particles can be calculated using the average particle size (nm) obtained by centrifugal sedimentation and the average primary particle size (nm) obtained by transmission electron microscope observation.
The sedimentation method, which is one of particle size measurements, is a method of measuring the particle size from the sedimentation velocity of particles in a liquid due to gravity or centrifugal force. Centrifugal sedimentation using centrifugal force can generally be applied to particles of 2 μm or less.
In the centrifugal sedimentation method that measures the particle size from the sedimentation speed of particles due to centrifugal force, the sedimentation speed (1) including the particle size measured as solid particles (particles without pores or cavities) is another method (e.g. average primary particle size measurement by transmission electron microscopy), including the particle size of particles of unknown density using Density in kinetic equations involving diameter is considered to be the density of the particle.

In the centrifugal sedimentation method, the sedimentation velocity is calculated by the Stokes sedimentation velocity formula.
V ₂ = particle sedimentation velocity (m/s), ρs = particle density (kg/m ³ ), ρ = dispersion medium (water) density (kg/m ³ ), d = particle diameter (m), Assuming that g = gravitational acceleration (m/s ² ) and η = dispersion medium (water) viscosity (Pa s), the Stokes sedimentation velocity equation is
Since V ₂ =g(ρs−ρ)d ² /18η,
The density of the particles at the sedimentation velocity (1) is the density of amorphous silica (ρs1) = 2.2, the density of water is 0.997, the average particle diameter (d1) nm measured by the centrifugal sedimentation method,
Assuming that the density (ds2) to be calculated of the particles of sedimentation velocity (2), the density of water is 0.997, and the average primary particle diameter (d2) nm by transmission electron microscope observation, sedimentation velocity (1) = sedimentation velocity (2),
(ρs1-0.997) (d1) = (ρs2-0.997) (d2) is established, and two particle size measurements obtained by the centrifugal sedimentation method and the average primary particle size by transmission electron microscope observation revealed silica The particle density (ρs2) is determined.

This is defined as equation (2).

In addition, in the silica particles having an internal space and through holes of the present invention, x indicates the composition ratio of the silica component in the silica particle, y indicates the composition ratio of the space in the silica particle (i.e., porosity), and the silica The particle has x+y=1. Then, when the density of amorphous silica = 2.2 and the density of water = 0.997, the density of the silica particles is
2.2x+0.997y=(ρs2) holds. This is defined as equation (3).
y=(2.2-ρs2)/1.203, and in terms of percentage, y can be multiplied by 100 to obtain 100y(%).

The silica particles of the present invention have an average primary particle size (A ₁ ) observed with a transmission electron microscope of 100 nm to 1.5 μm, and the average particle size (A ₂ )/average primary particle size (A ₁ ) ratio is 0.8 to 1.5.
Moreover, the specific surface area measured by the nitrogen gas adsorption method is 20 to 90 m ² /g.
In the present invention, silica particles are dispersed in an acidic or alkaline aqueous medium or organic solvent to obtain a silica sol having an average particle size (A ₂ ) of 100 nm to 1.5 μm as measured by a laser diffraction method.

The silica sol of the present invention is produced by a method including the following steps (a) to (b).
(a) step: the ratio D ₁ /D ₂ of the particle diameter (D ₁ ) measured by the dynamic light scattering method and the particle diameter (D ₂ ) measured by the nitrogen gas adsorption method is 4 to 10, and D ₁ is 40 ~ 200 nm, D ₂ of 8-30 nm, colloidal silica with a SiO ₂ concentration of 21-30 wt. a step of producing an alkaline porous secondary aggregate silica aqueous sol having an average particle size of 100 nm to 1.5 μm and a specific surface area of 90 to 350 m ² /g as measured by a nitrogen gas adsorption method;
(b) step: SiO ₂ /Na ₂ O molar ratio of 30 to 3000, SiO ₂ concentration of 0.1 to 30% by mass, pH adjusted to 3 to 11, and then at a temperature above 100° C. and below 270° C. A step of hydrothermally treating for 1 to 30 hours.
In the step (b), the hydrothermal temperature is above 100°C and below 270°C, or can be set between 150°C and 270°C, or between 150°C and 240°C, or between 150°C and 210°C. .

After the step (b), a step of replacing the aqueous medium with an organic solvent is performed to obtain an organosilica sol.

In the present invention, it becomes difficult to control the shape and particle size of secondary aggregated particles because secondary aggregation easily occurs and silica gelation easily occurs. At a silica concentration of 20% by mass, 25th-order aggregation easily occurs, and gelation of silica easily occurs, making it difficult to control the shape and particle diameter of secondary-aggregated particles. At a silica concentration of 20% by mass, 25th-order aggregation easily occurs, and gelation of silica easily occurs, making it difficult to control the shape and particle diameter of secondary-aggregated particles. At a silica concentration of 20% by mass, 25th-order aggregation easily occurs, and gelation of silica easily occurs, making it difficult to control the shape and particle diameter of secondary-aggregated particles. With a silica concentration of 20% by mass, the viscosity of the elongated colloidal silica used in step 25(a) depends on the D ₁ /D ₂ ratio. s is preferred. When the viscosity of the Brookfield viscometer is less than 10 mPa s, secondary aggregation of colloidal silica is unlikely to occur in the next high shear force stirring step, and when it exceeds 200 mPa s, the following high shear force stirring is difficult. Secondary agglomeration of colloidal silica tends to occur in the process, and gelation of silica tends to occur, making it difficult to control the shape and particle size of secondary agglomerated particles. Most preferably, the silica concentration is 21 to 30 mass % and the B-type viscosity at 25° C. is 10 to 100 mPa·s.
In the present invention, the aqueous silica sol composed of elongated colloidal silica, which is a raw material, must be alkaline. As the alkali species contained in the sol, NaOH is generally used, but KOH, LiOH, quaternary ammonium hydroxide, etc. may also be used.

The pH of this alkaline, elongated silica sol may vary depending on the alkaline species, but is preferably 8 to 11. If the pH is less than 8, spherical secondary agglomeration of colloidal silica is unlikely to occur in the subsequent stirring step with a high shearing force, and if it exceeds 11, dissolution of the raw material colloidal silica itself tends to occur, which is not preferable. The pH of the elongated silica sol as a raw material is particularly preferably 9 to 10.5.
In the step (a), the silica sol having an elongated alkaline shape is adjusted to have a silica concentration of 21 to 30% by mass. If the silica concentration is less than 20% by mass, the contact between the colloidal silica particles is reduced in the subsequent agitating step with a high shearing force, making it difficult for good secondary aggregation to occur. Further, when the silica concentration exceeds 30% by mass, the colloidal silica particles come into contact with each other too much in the subsequent stirring step with a high shearing force, and secondary aggregation of colloidal silica is remarkably likely to occur. It is not preferable because it becomes difficult to control the shape and particle size of the particles. The most preferable concentration of the elongated silica sol as a raw material is 21 to 25% by mass.

In the high-shearing stirring step, the alkaline, elongated silica sol whose concentration was adjusted in step (a) was stirred at 30 to 100° C. or 60 to 100° C. under high shearing force with a stirring device having a high shearing force. By heating for ~30 hours, porous secondary aggregated silica is generated, and at the same time gelation of elongated colloidal silica (that is, cluster aggregation, which is normal aggregation) occurs. is further aggregated to form tertiary aggregates (that is, tertiary aggregated silica) together with the elongated colloidal silica cluster aggregates. The tertiary aggregates are hydrous gel particles composed of secondary aggregated silica and elongated colloidal silica.

The size of the tertiary aggregate particles measured by a laser diffraction method is 100 nm to 1.5 μm. The liquid obtained in this step can be said to be a slurry of tertiary aggregated silica of elongated colloidal silica.
Examples of the agitating device having a high shearing force used in the step (a) include agitating devices having agitating blades such as paddle blades, turbine blades, screw blades, Faudler blades, and sawtooth impeller blades. In addition, the stirrer to be used must be capable of stirring at high speed. Although affected by the shape and size of the impeller, the rotating speed of the impeller was set at 1000 r.p.m. p. m. It is preferable to stir above. When the rotation speed of the stirring blade is 1000 r.p.m. p. m. If it is lower, only normal gelation (cluster aggregation) occurs, and it is difficult to obtain substantially spherical secondary aggregated silica.
A high-speed impeller disperser equipped with a saw-toothed impeller is particularly preferred as the agitator having a high shear force. The rotation speed of the stirring blade is 1000 r.p.m. p. m. 1500 r.p.m. p. m. The above is more preferable. Further, the rotation speed of the stirring blade was 5000 r.p.m. p. m. The following are preferable, and 4000 r.p.m. p. m. The following are more preferred.

In step (a), an alkaline elongated silica sol is heated to 30-100° C. under high shear stirring. If the heating temperature is less than 60°C, the intended tertiary aggregated silica cannot be obtained. On the other hand, if the heating temperature exceeds 100° C., although tertiary aggregated silica can be obtained, the rate of aggregation and gelation of the elongated colloidal silica becomes too fast, making it difficult to control aggregation, which is not preferable. . The heating temperature in the step (a) is particularly preferably 50 to 100°C.

The heating time at the heating temperature is 1 to 30 hours. If the heating time is less than 1 hour, the desired slurry of tertiary aggregated silica cannot be obtained. Even if the heating time exceeds 30 hours, the desired slurry of tertiary aggregated silica can be obtained, but it takes too much time and is not economical. The heating time is particularly preferably 5 to 20 hours.
The viscosity of the tertiary aggregated silica slurry of elongated colloidal silica obtained in the step (a) is 20 to 200 mPa·s at a silica concentration of 21% by mass and a Brookfield viscometer at 25°C.

The pH of the slurry of tertiary aggregated silica of elongated colloidal silica obtained in the step (a) is almost the same as the pH of the alkaline elongated silica sol as a raw material, and the colloidal silica constituting the tertiary aggregated silica. This indicates that almost no dehydration condensation occurs between the surface silanol groups of . The pH of the tertiary aggregated silica slurry of elongated colloidal silica obtained in the step (a) is 8 to 11, preferably 9 to 10.5.
In the step (a), the resulting alkaline slurry of tertiary aggregated silica is wet pulverized to break the tertiary aggregates, which are aggregates of the secondary aggregated silica, to obtain a secondary aggregated silica dispersion, That is, a porous secondary aggregated silica aqueous sol is obtained. The resulting alkaline porous secondary aggregated silica aqueous sol has a pH of 8 to 11, preferably 9 to 10.5.
A homogenizer, a pressure homogenizer, an ultrasonic homogenizer, an ultrasonic disperser, a mixer, a ball mill, a high-pressure jet counter-collision device, or the like can be used for the wet pulverization. Among them, a pressure homogenizer, an ultrasonic homogenizer, and an ultrasonic disperser are particularly preferred.
Wet pulverization can be performed at room temperature or under heating.

Wet pulverization is preferably carried out at a silica concentration in the slurry of alkaline tertiary aggregated silica in the range of 5 to 30% by mass. Even if the silica concentration is less than 5% by mass, pulverization is possible, but production efficiency is poor. On the other hand, when the silica concentration exceeds 30% by mass, pulverization is possible, but unpulverized tertiary aggregated silica tends to remain.
In the step (b), the alkaline porous secondary aggregated aqueous silica sol is adjusted to a SiO ₂ /Na ₂ O molar ratio of 30 to 3000, a SiO ₂ concentration of 0.1 to 30% by mass, and a pH of 3 to 11. It is a step of hydrothermally treating at a temperature above 100° C. and 300° C. or below, or above 100° C. and 270° C. or below for 1 to 30 hours.

The pH of the aqueous silica sol is adjusted to about 10 when the alkaline porous secondary aggregation aqueous silica sol is used as it is. Therefore, when the pH is adjusted to be higher than 10, it can be adjusted by adding an alkaline component such as sodium hydroxide or potassium hydroxide to the alkaline porous secondary aggregation aqueous silica sol. The alkaline porous secondary flocculated aqueous silica sol is washed with a cation exchange resin or an ultrafiltration membrane to partially remove alkaline components, and an acidic porous secondary flocculated aqueous silica sol can be used.
The molar ratio of SiO ₂ /Na ₂ O is preferably 30-3000, more preferably 70-2000.
If the molar ratio of SiO ₂ /Na ₂ O is less than 30, the amount of alkaline components is too large, and the silica particles tend to dissolve during the hydrothermal treatment, which is not preferable. On the other hand, if the molar ratio of SiO ₂ /Na ₂ O is more than 3000, the amount of alkali component is too small, so that the silica particles are less likely to grow due to dissolution and precipitation during the hydrothermal treatment. This is not preferable because particles are less likely to be generated.

The hydrothermal temperature is preferably over 100°C and 300°C or less, or over 100°C and 270°C or less, more preferably 160 to 220°C. A hydrothermal temperature of 100° C. or less is not preferable because silica particles having a net-like outer shell are not sufficiently formed. Further, at a hydrothermal temperature higher than 300°C, the aqueous silica sol itself may gel and solidify, which is not preferable.
The SiO ₂ concentration of the aqueous silica sol to be hydrothermally treated is preferably 0.1 to 30% by mass, more preferably 10 to 30% by mass. Even if it is less than 0.1% by mass, spherical silica particles having a net-like shell can be produced, but the productivity is poor, which is not preferable. Moreover, if the SiO ₂ concentration is higher than 30% by mass, the aqueous silica sol itself may gel, which is not preferable.
The pH of the aqueous silica sol to be hydrothermally treated is preferably 3 to 11, and if it is less than 3, the silica particles having a net-like shell of the present invention are not sufficiently formed, which is not preferred. Moreover, if the pH is higher than 11, the silica particles are likely to dissolve during the hydrothermal treatment, which is not preferable.

From the aqueous dispersion of silica particles (silica sol) of the present invention obtained in the step (b), alkaline components are removed by ion exchange to obtain an acidic aqueous dispersion.
Removal of alkaline components by ion exchange can be carried out by a known method. Known methods include a column method in which the alkaline aqueous dispersion is passed through a column filled with a cation exchange resin, or a resin injection method in which the cation exchange resin is thrown into the aqueous dispersion and stirred. be able to.
Both strongly acidic and weakly acidic cation exchange resins can be used, but strongly acidic cation exchange resins such as Amberlite-120B (trade name) are particularly preferred.
The removal of alkaline components by ion exchange can be carried out at room temperature, but can also be carried out under heating.

The removal by ion exchange of the alkali component in the resin charging method can control the pH of the acidic aqueous dispersion after ion exchange to 3-6. In the column method, the resulting acidic aqueous dispersion has a pH of 3-4.
The aqueous dispersion (silica sol) of the silica particles of the present invention obtained in the above step (b) can be subjected to a step of replacing the aqueous medium with an organic solvent to obtain an organosilica sol.
The method of replacing water with an organic solvent can be carried out by a known method such as an evaporation method under atmospheric or reduced pressure, an ultrafiltration method, or a sedimentation separation redispersion method. The replacement of the organic solvent is preferably carried out at a silica concentration of 10 to 50% by mass, more preferably 20 to 40% by mass, in the aqueous sol in which the silica particles of the present invention are dispersed.

Usable organic solvents include alcohols such as methanol, ethanol, isopropanol and butanol, polyhydric alcohols such as ethylene glycol and propylene glycol, ethers such as ethylene glycol monomethyl ether and dimethyl ether, N-methylpyrrolidone and dimethylacetamide. , dimethylformamide and the like.
In addition, aqueous sol obtained by treating the surface of the silica particles of the present invention with a silane coupling agent, a silylating agent, etc. to improve dispersibility in hydrophilic solvents, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, acrylic monomers It is possible to obtain an organosol dispersed in a hydrophobic solvent such as

The hydrolyzable silanes used for surface coating the silica particles of the present invention can include hydrolyzable silanes of formula (4) and/or hydrolyzable silanes of formula (5). The hydrolyzable silane of formula (4) and the hydrolyzable silane of formula (5) can be used in combination with other hydrolyzable silanes, and the hydrolyzable silane of formula (4) and/or formula The weight ratio of hydrolyzable silane (5) to other hydrolyzable silane can be in the range of 1:0.1 to 1.0 or 1:0.5 to 1.0.

The surface coating amount of the silica particles of the present invention is 0.1/nm ² to 3.0/nm ² or 0.3/nm as the number of Si atoms of the silane compound coated on the silica particle surface. It can be used in the range of ² to 1.5/nm ² . The surface coating amount is the mass of the hydrolyzable silane added to the silica particles, and can be calculated from the specific surface area of the silica particles and the amount of the hydrolyzable silane added.

In formula (4), R ¹ includes an acryloxy group, a methacryloxy group, an aryl group, an alkyl group, a glycidoxy group, an amino group, or an alkylene group having 1 to 10 carbon atoms containing these functional groups, and the Si atom is Si- C bonds, R ² is a hydrolyzable group consisting of an alkoxy group, an acyloxy group, or a halogen group, and at least one hydrolyzable group of R ² forms Si—O—Si on the silica particle surface. A bond is formed and a represents an integer of 1-3.
In formula (5), R ³ is an alkyl group and is bonded to a silicon atom via a Si—C bond, R ⁴ is an alkoxy group, an acyloxy group, or a halogen group, and Y is an alkylene group or arylene. group, NH group, or oxygen atom, b is an integer of 0 to 3, and c is an integer of 0 or 1.

The above alkyl group is an alkyl group having 1 to 10 carbon atoms, such as methyl group, ethyl group, n-propyl group, i-propyl group, cyclopropyl group, n-butyl group, i-butyl group, s-butyl group. group, t-butyl group, cyclobutyl group, 1-methyl-cyclopropyl group, 2-methyl-cyclopropyl group, n-pentyl group, 1-methyl-n-butyl group, 2-methyl-n-butyl group, 3 -methyl-n-butyl group, 1,1-dimethyl-n-propyl group, 1,2-dimethyl-n-propyl group, 2,2-dimethyl-n-propyl group, 1-ethyl-n-propyl group, cyclopentyl group, 1-methyl-cyclobutyl group, 2-methyl-cyclobutyl group, 3-methyl-cyclobutyl group, 1,2-dimethyl-cyclopropyl group, 2,3-dimethyl-cyclopropyl group, 1-ethyl-cyclopropyl group, 2-ethyl-cyclopropyl group, n-hexyl group, 1-methyl-n-pentyl group, 2-methyl-n-pentyl group, 3-methyl-n-pentyl group, 4-methyl-n-pentyl group , 1,1-dimethyl-n-butyl group, 1,2-dimethyl-n-butyl group, 1,3-dimethyl-n-butyl group, 2,2-dimethyl-n-butyl group, 2,3-dimethyl -n-butyl group, 3,3-dimethyl-n-butyl group, 1-ethyl-n-butyl group, 2-ethyl-n-butyl group, 1,1,2-trimethyl-n-propyl group, 1, 2,2-trimethyl-n-propyl group, 1-ethyl-1-methyl-n-propyl group, 1-ethyl-2-methyl-n-propyl group, cyclohexyl group, 1-methyl-cyclopentyl group, 2-methyl -cyclopentyl group, 3-methyl-cyclopentyl group, 1-ethyl-cyclobutyl group, 2-ethyl-cyclobutyl group, 3-ethyl-cyclobutyl group, 1,2-dimethyl-cyclobutyl group, 1,3-dimethyl-cyclobutyl group, 2,2-dimethyl-cyclobutyl group, 2,3-dimethyl-cyclobutyl group, 2,4-dimethyl-cyclobutyl group, 3,3-dimethyl-cyclobutyl group, 1-n-propyl-cyclopropyl group, 2-n- propyl-cyclopropyl group, 1-i-propyl-cyclopropyl group, 2-i-propyl-cyclopropyl group, 1,2,2-trimethyl-cyclopropyl group, 1,2,3-trimethyl-cyclopropyl group, 2,2,3-trimethyl-cyclopropyl group, 1-ethyl-2-methyl-cyclopropyl group, 2-ethyl-1-methyl-cyclopropyl group , 2-ethyl-2-methyl-cyclopropyl group and 2-ethyl-3-methyl-cyclopropyl group.

Further, examples of the alkylene group include alkylene groups derived from the above alkyl groups.

The aryl group includes, for example, a phenyl group, a naphthyl group, an anthryl group, and the like, and the arylene group is a group derived from the above aryl group, and includes a phenylene group, a naphthylene group, an anthrylene group, and the like.

Examples of the alkoxy group include those having 1 to 10 carbon atoms, such as methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t -butoxy group, n-pentyloxy group, 1-methyl-n-butoxy group, 2-methyl-n-butoxy group, 3-methyl-n-butoxy group, 1,1-dimethyl-n-propoxy group, 1,2 -dimethyl-n-propoxy group, 2,2-dimethyl-n-propoxy group, 1-ethyl-n-propoxy group, n-hexyloxy group, 1-methyl-n-pentyloxy group, 2-methyl-n-pentyloxy group , 3-methyl-n-pentyloxy group, 4-methyl-n-pentyloxy group, 1,1-dimethyl-n-butoxy group, 1,2-dimethyl-n-butoxy group, 1,3-dimethyl-n-butoxy group group, 2,2-dimethyl-n-butoxy group, 2,3-dimethyl-n-butoxy group, 3,3-dimethyl-n-butoxy group, 1-ethyl-n-butoxy group, 2-ethyl-n- butoxy group, 1,1,2-trimethyl-n-propoxy group, 1,2,2-trimethyl-n-propoxy group, 1-ethyl-1-methyl-n-propoxy group and 1-ethyl-2-methyl- cyclopropoxy, cyclobutoxy, 1-methyl-cyclopropoxy, 2-methyl-cyclopropoxy, cyclopentyloxy and 1-methyl-cyclobutoxy as cyclic alkoxy groups; , 2-methyl-cyclobutoxy group, 3-methyl-cyclobutoxy group, 1,2-dimethyl-cyclopropoxy group, 2,3-dimethyl-cyclopropoxy group, 1-ethyl-cyclopropoxy group, 2-ethyl-cyclo propoxy group, cyclohexyloxy group, 1-methyl-cyclopentyloxy group, 2-methyl-cyclopentyloxy group, 3-methyl-cyclopentyloxy group, 1-ethyl-cyclobutoxy group, 2-ethyl-cyclobutoxy group, 3-ethyl-cyclobutoxy group, 1,2-dimethyl-cyclobutoxy group, 1,3-dimethyl-cyclobutoxy group, 2,2-dimethyl-cyclobutoxy group, 2,3-dimethyl-cyclobutoxy group, 2, 4-dimethyl-cyclobutoxy group, 3,3-dimethyl-cyclobutoxy group, 1-n-propyl-cyclopropoxy group, 2-n-propyl-cyclopropoxy group, 1-i-propyl-cyclopropoxy group, 2- i-propyl-cyclopropoxy group, 1,2,2-trimethyl Chill-cyclopropoxy group, 1,2,3-trimethyl-cyclopropoxy group, 2,2,3-trimethyl-cyclopropoxy group, 1-ethyl-2-methyl-cyclopropoxy group, 2-ethyl-1-methyl- Cyclopropoxy group, 2-ethyl-2-methyl-cyclopropoxy group, 2-ethyl-3-methyl-cyclopropoxy group and the like.

The acyloxy group having 2 to 10 carbon atoms is, for example, a methylcarbonyloxy group, an ethylcarbonyloxy group, an n-propylcarbonyloxy group, an i-propylcarbonyloxy group, an n-butylcarbonyloxy group, i-butyl carbonyloxy group, s-butylcarbonyloxy group, t-butylcarbonyloxy group, n-pentylcarbonyloxy group, 1-methyl-n-butylcarbonyloxy group, 2-methyl-n-butylcarbonyloxy group, 3-methyl -n-butylcarbonyloxy group, 1,1-dimethyl-n-propylcarbonyloxy group, 1,2-dimethyl-n-propylcarbonyloxy group, 2,2-dimethyl-n-propylcarbonyloxy group, 1-ethyl -n-propylcarbonyloxy group, n-hexylcarbonyloxy group, 1-methyl-n-pentylcarbonyloxy group, 2-methyl-n-pentylcarbonyloxy group, 3-methyl-n-pentylcarbonyloxy group, 4- methyl-n-pentylcarbonyloxy group, 1,1-dimethyl-n-butylcarbonyloxy group, 1,2-dimethyl-n-butylcarbonyloxy group, 1,3-dimethyl-n-butylcarbonyloxy group, 2, 2-dimethyl-n-butylcarbonyloxy group, 2,3-dimethyl-n-butylcarbonyloxy group, 3,3-dimethyl-n-butylcarbonyloxy group, 1-ethyl-n-butylcarbonyloxy group, 2- ethyl-n-butylcarbonyloxy group, 1,1,2-trimethyl-n-propylcarbonyloxy group, 1,2,2-trimethyl-n-propylcarbonyloxy group, 1-ethyl-1-methyl-n-propyl carbonyloxy group, 1-ethyl-2-methyl-n-propylcarbonyloxy group, phenylcarbonyloxy group, tosylcarbonyloxy group and the like.

Examples of the halogen group include fluorine, chlorine, bromine and iodine.
Examples of the above hydrolyzable silanes include the following compounds.

In the above formula, ^R2 represents a hydrolyzable group consisting of an alkoxy group, an acyloxy group, or a halogen group. These are available as silane coupling agents manufactured by Shin-Etsu Chemical Co., Ltd.

The compound of formula (5) contains a trimethylsilylating agent and includes hexamethyldisilane, hexamethyldisiloxane, hexamethyldisilazane and the like. These silylating agents are available from Tokyo Chemical Industry Co., Ltd.

The surface treatment of silica particles with a silane compound can be carried out, for example, by adding a hydrolyzable silane of formula (4) and/or formula (5) to a methanol sol of silica particles for hydrolysis and surface coating.
For hydrolysis of an alkoxysilyl group, acyloxysilyl group or silyl halide group, 0.5 to 100 mol, preferably 1 to 10 mol of water is used per 1 mol of hydrolyzable group.

Also, the hydrolysis catalyst can be used in an amount of 0.001 to 10 mol, preferably 0.001 to 1 mol, per 1 mol of the hydrolyzable group.

The reaction temperature for hydrolysis and condensation is usually 20 to 80°C.

The hydrolysis may be a complete hydrolysis or a partial hydrolysis. That is, the hydrolyzate and the monomer may remain in the hydrolyzed condensate.

A catalyst can be used during the hydrolysis and condensation.

A chelate compound, an organic acid, an inorganic acid, an organic base, or an inorganic base can be used in combination as the hydrolysis catalyst.
Alternatively, the silica particle dispersion of the present invention is dried with a spray dryer and then baked at 150 to 600° C. to obtain a spherical silica powder having an average particle size (volume basis) of 1 to 50 μm by laser diffraction method. be able to.
Alternatively, after drying an acidic silica aqueous dispersion (silica sol) or silica organic solvent dispersion (organosilica sol) by a method such as normal pressure, reduced pressure, freezing, etc., and then pulverizing it with a dry pulverizer such as a mortar mill, a mill, or a mixer. , 150 to 600° C. to obtain silica powder. In this case, if the dry pulverization is too strong, the silica particles will be partially destroyed.
These silica powders can be used as catalyst carriers, adsorbents, antiglare agents, antiblocking agents, heat insulating materials, substitutes for mesoporous silica, and the like.
The film-forming composition of the present invention is a composition that contains the silica particles of the present invention and a matrix component and is capable of forming a film or coating film. The matrix component is not particularly limited as long as it is a resin component capable of forming a film, and resins, resin solutions, monomers, various binders and the like can be used. These resins include photocurable resins and thermosetting resins.

The silica particles can be added as silica sol or as silica powder.
The content of the silica particles of the present invention is 10 parts by mass to 1000 parts by mass, or 50 parts by mass to 500 parts by mass, or 50 parts by mass to 300 parts by mass with respect to 100 parts by mass of the curable resin. can do things
Photocurable resin has radical curing and cationic curing in its curing mechanism, and is a resin in which a crosslinked structure is formed by reaction between oligomers and monomers having polymerizability such as vinyl groups, (meth)acryloyl groups, and epoxy groups. Either can be used.
Photocurable resins include photopolymerizable oligomers and photopolymerizable monomers, photopolymerization initiators, additives (for example, polymerization inhibitors, fillers, pigments, dyes, leveling agents, erasing materials, viscosity modifiers, surface active agents, rheology modifiers, slip agents, water repellants, etc.) and solvents.
Examples of photoradical UV curable resins include photopolymerizable oligomers such as urethane acrylate, epoxy acrylate, acrylic acrylate, and polyester acrylate.

Examples of photopolymerizable monomers include polyfunctional (difunctional to octafunctional) acrylates and monofunctional acrylates.
For example, a urethane acrylate can be synthesized from a polyol and a diisocyanate (or isocyanate) and an acrylate having an OH group. A bifunctional urethane acrylate is obtained using a bifunctional polyol as a raw material, and a polyfunctional urethane acrylate is obtained when a trifunctional or higher polyol is used. A polyfunctional acrylate having an OH group can also be used.
Isocyanates include 2-acryloyloxyethyl isocyanate.
Diisocyanates include 2,4-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,6-hexanediol diisocyanate, isophorone diisocyanate and the like.

Acrylates having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxybutyl acrylate, pentaerythritol triacrylate and the like.
Benzophenone-based, acetophenone-based, benzoin ether-based, and thioxanthone-based photopolymerization initiators can be used.

In the photoradical reaction, a monomer reacts with an active species (neutral radical) generated from a small amount of an initiator to generate a monomer radical (initiation reaction), and this reaction occurs continuously to polymerize. The photopolymerization initiator mainly absorbs energy in the ultraviolet region with a wavelength of 190 to 500 nm, and when it is excited, it causes intramolecular cleavage to generate radicals, or it generates radicals by abstracting hydrogen from a hydrogen donor, Polymerization is initiated by reacting with the heavy bond. UV irradiation systems include UV lamps (high-pressure mercury lamps), metal halide lamps, LED-UV, and the like.
Photoradical polymerization initiators include, for example, imidazole compounds, diazo compounds, bisimidazole compounds, N-arylglycine compounds, organic azide compounds, titanocene compounds, aluminate compounds, organic peroxides, N-alkoxypyridinium salt compounds, and thioxanthone compounds. etc. Azide compounds include p-azidobenzaldehyde, p-azidoacetophenone, p-azidobenzoic acid, p-azidobenzalacetophenone, 4,4'-diazidochalcone, 4,4'-diazidodiphenyl sulfide, and 2, 6-bis(4′-azidobenzal)-4-methylcyclohexanone and the like can be mentioned. Diazo compounds include 1-diazo-2,5-diethoxy-4-p-tolylmercaptobenzene borofluoride, 1-diazo-4-N,N-dimethylaminobenzene chloride, and 1-diazo-4-N, Examples include N-diethylaminobenzene borofluoride and the like. Bisimidazole compounds include 2,2′-bis(o-chlorophenyl)-4,5,4′,5′-tetrakis(3,4,5-trimethoxyphenyl)1,2′-bisimidazole, and 2 ,2′-bis(o-chlorophenyl)4,5,4′,5′-tetraphenyl-1,2′-bisimidazole and the like. Titanocene compounds include dicyclopentadienyl-titanium-dichloride, dicyclopentadienyl-titanium-bisphenyl, and dicyclopentadienyl-titanium-bis(2,3,4,5,6-pentafluorophenyl). , dicyclopentadienyl-titanium-bis(2,3,5,6-tetrafluorophenyl), dicyclopentadienyl-titanium-bis(2,4,6-trifluorophenyl), dicyclopentadienyl -titanium-bis(2,6-difluorophenyl), dicyclopentadienyl-titanium-bis(2,4-difluorophenyl), bis(methylcyclopentadienyl)-titanium-bis(2,3,4, 5,6-pentafluorophenyl), bis(methylcyclopentadienyl)-titanium-bis(2,3,5,6-tetrafluorophenyl), bis(methylcyclopentadienyl)-titanium-bis(2, 6-difluorophenyl), and dicyclopentadienyl-titanium-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl).
Also, 1,3-di(tert-butyldioxycarbonyl)benzophenone, 3,3′,4,4′-tetrakis(tert-butyldioxycarbonyl)benzophenone, 3-phenyl-5-isoxazolone, 2-mercapto benzimidazole, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)- Butanone etc. can be mentioned.
The constituent components of the photo cationic UV curable resin may include a photopolymerizable oligomer or photopolymerizable monomer, a photopolymerization initiator, and a solvent.

Examples of photopolymerizable oligomers include alicyclic epoxies, glycidyl type epoxies, and oxetane compounds, and examples of photopolymerizable monomers include vinyl ether monomers.
Oligomers and monomers used for photocationic curing include, for example, glycidyl ether epoxy resins, hydrogenated epoxy resins, alicyclic epoxy resins, oxetane resins, vinyl ether resins, and maleimide resins.
Cationic polymerization initiators include sulfonium salt type and iodonium salt type. Utilizing the characteristics of low viscosity, transparency, adhesion and curability of cationic polymer compounds, it is used for displays and devices.

An ionic onium salt composed of a cationic part and an anionic part is used as the photocationic polymerization initiator. The cationic part absorbs light and the anionic part serves as an acid generation source. Cationic components include sulfonium ions and iodonium ions, and anionic components include SbF ₆ ⁻ , PF ₆ ⁻ , and B(C ₆ F ₅ ) ₄ ⁻ .
For example, in the case of an epoxy compound, the acid is coordinated to the epoxy and reacts with another epoxy group to generate an oxonium cation that serves as an active species, and ring-opening polymerization proceeds.

Examples of photocationic polymerization initiators include sulfonic acid esters, sulfonimide compounds, disulfonyldiazomethane compounds, dialkyl-4-hydroxysulfonium salts, arylsulfonic acid-p-nitrobenzyl esters, silanol-aluminum complexes, and (η ⁶ -benzene). (η ⁵ -cyclopentadienyl) iron (II) and the like.
Examples of sulfonimide compounds include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoro-normal-butanesulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide and N-(trifluoromethanesulfonyloxy)naphthalimide. is mentioned.
Examples of disulfonyldiazomethane compounds include bis(trifluoromethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, and bis(2,4-dimethylbenzenesulfonyl). ) diazomethane, and methylsulfonyl-p-toluenesulfonyl diazomethane.

The aromatic iodonium salt compounds include diphenyliodonium chloride, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium mesylate, diphenyliodonium tosylate, diphenyliodonium bromide, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluoroantimonate, diphenyliodonium hexafluoroarsenate. bis(p-tert-butylphenyl)iodonium hexafluorophosphate, bis(p-tert-butylphenyl)iodonium mesylate, bis(p-tert-butylphenyl)iodonium tosylate, bis(p-tert-butylphenyl) ) iodonium trifluoromethanesulfonate, bis(p-tert-butylphenyl)iodonium tetrafluoroborate, bis(p-tert-butylphenyl)iodonium chloride, bis(p-chlorophenyl)iodonium chloride, bis(p-chlorophenyl)iodonium tetrafluoro Borate, also bis(alkylphenyl)iodonium salts such as bis(4-t-butylphenyl)iodonium hexafluorophosphate, alkoxycarbonylalkoxy-trialkylaryliodonium salts (e.g. 4-[(1-ethoxycarbonyl-ethoxy)phenyl ]-(2,4,6-trimethylphenyl)-iodonium hexafluorophosphate, etc.), bis(alkoxyaryl)iodonium salts (e.g., bis(alkoxyphenyl)iodonium such as (4-methoxyphenyl)phenyliodonium hexafluoroantimonate salt).

Examples of aromatic sulfonium salt compounds include triphenylsulfonium chloride, triphenylsulfonium bromide, tri(p-methoxyphenyl)sulfonium tetrafluoroborate, tri(p-methoxyphenyl)sulfonium hexafluorophosphonate, tri(p-ethoxyphenyl) ) triphenylsulfonium salts such as sulfonium tetrafluoroborate, triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, (4-phenylthiophenyl) diphenylsulfonium hexafluoroantimonate, (4 -phenylthiophenyl)diphenylsulfonium hexafluorophosphate, bis[4-(diphenylsulfonio)phenyl]sulfide-bis-hexafluoroantimonate, bis[4-(diphenylsulfonio)phenyl]sulfide-bis-hexafluorophosphate, (4-methoxyphenyl)diphenylsulfonium hexafluoroantimonate) and other sulfonium salts.
Phosphonium salts such as triphenylphosphonium chloride, triphenylphosphonium bromide, tri(p-methoxyphenyl)phosphonium tetrafluoroborate, tri(p-methoxyphenyl)phosphonium hexafluorophosphonate, tri(p-ethoxyphenyl)phosphonium tetrafluoroborate, 4 - Phosphonium salts such as chlorobenzenediazonium hexafluorophosphate and benzyltriphenylphosphonium hexafluoroantimonate.

The photopolymerization initiator is 0.01 part by mass to 50 parts by mass, or 0.1 part by mass to 15 parts by mass with respect to 100 parts by mass of the polymerizable compound (photopolymerizable oligomer or photopolymerizable monomer). can be used in
Thermosetting resins such as phenol resins, amino resins, epoxy resins, and unsaturated polyester resins are linear low-molecular-weight compounds (prepolymers, oligomers) before heating. The conversion/crosslinking reaction proceeds to form a three-dimensional structure. A thermosetting resin is composed of a resin skeleton, a bonding group, and a functional group. Functional groups include hydroxyl groups, glycidyl groups, alicyclic epoxy groups, maleimide groups, and cyanate groups. A linking group includes an ether structure, an ester structure, and an amine structure. Examples of the resin skeleton include bisphenol A type, novolac type, resol type, diphenylmethane type, biphenyl type, hydrogenated bisphenol type, and polypropylene glycol type.
In some cases, it cures alone, but in many cases, it can be used in combination with a curing agent. Curing agents for epoxy resins include amine-based and acid anhydride-based curing agents.

The above curing agent can be used in the range of 0.01 to 50 parts by mass, or 0.1 to 15 parts by mass with respect to 100 parts by mass of the thermally polymerizable resin.
Surfactants include cationic surfactants, anionic surfactants, amphoteric surfactants, nonionic surfactants, silicone-based surface modifiers, fluorine-based surfactants, and the like.

Examples of cationic surfactants include alkylamine salt types such as monoalkylamine salts, dialkylamine salts, and trialkylamine salts, halogenated (fluorinated, chlorinated, brominated, or iodinated) alkyltrimethylammonium, halogenated ( quaternary ammonium salt types such as fluorinated, chlorinated, brominated, or iodinated dialkyldimethylammonium, halogenated (fluorinated, chlorinated, brominated, or iodinated) alkylbenzalkonium;

Examples of anionic surfactants include carboxylic acid types such as aliphatic monocarboxylates, polyoxyethylene alkyl ether carboxylates, N-acylsarcosine salts, and N-acylglutamates, dialkylsulfosuccinates, alkanesulfonates, Sulfones such as alpha olefin sulfonates, linear alkylbenzene sulfonates, alkyl (branched) benzene sulfonates, naphthalene sulfonates-formaldehyde condensates, alkyl naphthalene sulfonates, N-methyl-N-acyl taurate salts, etc. Acid type, sulfuric acid ester type such as alkyl sulfate, polyoxyethylene alkyl ether sulfate, oil sulfate ester salt, alkyl phosphate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkylphenyl ether phosphate, etc. Phosphate ester type.

Examples of amphoteric surfactants include alkyl betaine, carboxy betaine type such as fatty acid amidopropyl betaine, 2-alkyl imidazoline derivative type such as 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, alkyl (or glycine type such as dialkyl)diethylenetriaminoacetic acid, and amine oxide type such as alkylamine oxide.

Examples of nonionic surfactants include ester types such as glycerin fatty acid esters, sorbitan fatty acid esters and sucrose fatty acid esters; ether types such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers and polyoxyethylene polyoxypropylene glycol; Examples include ester ether types such as fatty acid polyethylene glycol and fatty acid polyoxyethylene sorbitan, and alkanolamide types such as fatty acid alkanolamide.

Each of these surfactants may be one in which some or all of the hydrogen atoms in the alkyl chain are substituted with halogen atoms (fluorine, chlorine, bromine, iodine).
Examples of fluorosurfactants include tetrafluoroethylene, perfluoroalkylammonium salts, perfluoroalkylsulfonic acid amides, sodium perfluoroalkylsulfonates, perfluoroalkylpotassium salts, perfluoroalkylcarboxylates, perfluoro Alkyl sulfonates, perfluoroalkylethylene oxide adducts, perfluoroalkyltrimethylammonium salts, perfluoroalkylaminosulfonates, perfluoroalkyl phosphates, perfluoroalkylalkyl compounds, perfluoroalkylalkylbetaines, perfluoroalkylhalogens compounds and the like.

Examples of silicone-based surface modifiers (silicone-based surfactants) include dimethyl silicone, aminosilane, acrylsilane, vinylbenzylsilane, vinylbenzylaminosilane, glycidosilane, mercaptosilane, dimethylsilane, polydimethylsiloxane, polyalkoxysiloxane, hydro Diene-modified siloxane, vinyl-modified siloxane, bitroxy-modified siloxane, amino-modified siloxane, carboxyl-modified siloxane, halogenated-modified siloxane, epoxy-modified siloxane, methacryloxy-modified siloxane, mercapto-modified siloxane, fluorine-modified siloxane, alkyl group-modified siloxane, phenyl-modified siloxane, Alkylene oxide-modified siloxane and the like can be mentioned.
The above surfactant can be added in the range of 0.01% to 10% by mass, or 2% to 5% by mass with respect to the film-forming composition.

The film-forming component can add a rheology modifier to improve fluidity. For example, phthalic acid derivatives such as dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate, and butyl isodecyl phthalate; adipic acid derivatives such as di-n-butyl adipate, diisobutyl adipate, diisooctyl adipate, and octyldecyl adipate; , diethyl maleate, dinonyl maleate, and other maleic acid derivatives; methyl oleate, butyl oleate, tetrahydrofurfuryl oleate, and other oleic acid derivatives; and normal butyl stearate, glyceryl stearate, and other stearic acid derivatives. These rheology modifiers can be added in the range of 0.01% by mass to 10% by mass, or 2% by mass to 5% by mass with respect to the film-forming composition.

The film-forming composition may contain a leveling agent. These leveling agents are, for example, polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether, polyoxyethylene nonylphenol. Polyoxyethylene alkylallyl ethers such as ethers, polyoxyethylene/polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate Nonionic surfactants such as sorbitan fatty acid esters, Ftop EF301, EF303, EF352 (manufactured by Tochem Products Co., Ltd., trade names), Megafac F171, F173, R-30 (manufactured by Dainippon Ink Co., Ltd., commercial products name), Florard FC430, FC431 (manufactured by Sumitomo 3M Limited, trade name), Asahiguard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd., trade name), etc. and organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.). These leveling agents can be added in the range of 0.01% by mass to 10% by mass, or 2% by mass to 5% by mass with respect to the film-forming composition.

As the solvent used for the film-forming composition, any solvent can be used without particular limitation as long as it is capable of dissolving the above solid content as the solvent used for the coating composition of the present invention. Examples of such solvents include methanol, ethanol, n-propanol, iso-propanol, butanol, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, methyl isobutyl carbinol, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, Ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether , propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, propylene Glycol dibutyl ether, ethyl lactate, propyl lactate, isopropyl lactate, butyl lactate, isobutyl lactate, methyl formate, ethyl formate, propyl formate, isopropyl formate, butyl formate, isobutyl formate, amyl formate, isoamyl formate, methyl acetate, ethyl acetate, acetic acid amyl, isoamyl acetate, hexyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, butyl propionate, propionate isobutyl pionate, methyl butyrate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, ethyl hydroxyacetate, ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxy-2-methylpropionate, 2- methyl hydroxy-3-methylbutyrate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-methoxybutyl acetate, 3-methoxypropyl acetate, 3 -methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butyrate, methyl acetoacetate, toluene, xylene, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, 2-heptanone, 3-heptanone, 4-heptanone, cyclohexanone, N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpyrrolidone, 4-methyl-2-pentanol, and γ- Butyrolactone and the like can be mentioned. These solvents can be used alone or in combination of two or more.

Examples of methods for preparing the film-forming composition include a method of kneading silica particles into a resin, a method of mixing a silica particle dispersion with a resin solution, and a method of mixing a resin precursor with silica particles or a dispersion of silica particles. methods and the like. The coating liquid, which is an example of the film-forming composition of the present invention, is less prone to sedimentation of particles and tends to maintain uniformity.
Forms of silica-containing films of the present invention include the films themselves or coatings produced on films or other forms of articles.
Since the matrix of the film of the present invention penetrates into the inside of the particles, the transparency is good and the particles are less likely to fall off. Although the amount of addition varies depending on the application, adding a small amount of silica can impart good anti-blocking properties, slip properties, and anti-glare properties.

on substrates (such as film sheets, silicon wafer substrates, silicon/silicon dioxide coated substrates, silicon nitride substrates, glass substrates, ITO substrates, polyimide substrates, and low-k material coated substrates) The film-forming (coating) composition of the present invention is applied by an appropriate coating method such as a spinner, a coater, etc., and then heated to form a coating film (a film made of a thermoset of the coating composition) by thermosetting. be done. The heating conditions are appropriately selected from a heating temperature of 20° C. to 250° C. or 20° C. to 110° C. and a heating time of 0.3 minutes to 60 minutes. Here, the film thickness of the coating film to be formed is, for example, 0.01 μm to 10 μm, 0.02 μm to 8 μm, 0.05 μm to 6 μm, or 0.1 μm to 5 μm. .

When the coated coating film is photocured, it is dried at 20 ° C. to 100 ° C. for a heating time of 0.3 to 60 minutes to remove the solvent, and then using ultraviolet rays with a wavelength of 190 nm to 500 nm. Then, a coating film was formed by photocuring with an exposure amount of 1 mJ/cm ² to 20000 mJ/cm ² , 10 mJ/cm ² to 15000 mJ/cm ² or 50 mJ/cm ² to 11000 mJ/cm ² . The thickness of the coating film to be formed is, for example, 0.01 μm to 10 μm, 0.02 μm to 8 μm, 0.05 μm to 6 μm, or 0.1 μm to 5 μm.

In the present invention, in the case of a photo-curing system, it is possible to use heat curing and photo-curing together. It is possible to heat-cure first and then photo-cure, or to photo-cure and then heat-cure.

In each synthesis example below, the conductivity and pH were measured at 20° C. unless otherwise specified.
All B-type viscosity measurements were performed at 25° C. unless otherwise specified. Moreover, the average particle size by the laser diffraction method is a volume-based value.

(Measuring device/method)
- pH: A pH meter (manufactured by Toa DKK Co., Ltd.) was used.
- Electric conductivity: An electric conductivity meter (manufactured by Toa DKK Co., Ltd.) was used.
- Viscosity: A B-type viscometer (manufactured by Toki Sangyo Co., Ltd.) was used.
- Na ₂ O content in silica sol: measured by atomic absorption spectrometry after decomposing silica particles with hydrofluoric acid.
· SiO ₂ concentration of silica sol: The SiO ₂ concentration was obtained by subtracting the Na ₂ O content from the residue after firing at 1000°C after drying.
- Average primary particle size (A ₁ ) of silica particles of the present invention observed by transmission electron microscope: The particle morphology was observed by a transmission electron microscope.
• Average particle size (A ₂ ) of silica particles of the present invention measured by laser diffraction method: An aqueous dispersion of silica particles was measured using a laser diffraction particle size analyzer SALD-7500 (manufactured by Shimadzu Corporation).

• Average diameter of the silica component constituting the network of silica particles of the present invention: Measured according to the above formula (1).
- Measurement of porosity in the silica particles of the present invention: Measured according to the above formulas (2) and (3).
-Area ratio of through-holes in the TEM plan projection view of the silica particles of the present invention: From the transmission electron micrograph, the part where the silica in the particles is not present and the background can be seen through is defined as the through-hole, and within the outer shell of the through-hole was measured.
- Average particle size of the silica particles of the present invention by centrifugal sedimentation method: An aqueous dispersion of silica particles was measured using a centrifugal sedimentation particle size measuring device CAPA-700 (manufactured by Horiba, Ltd.), and the true density of the silica particles was determined to be 2. .2 g/cm ³ .
- Specific surface area of elongated silica particles used as a raw material: A nitrogen gas adsorption method specific surface area measuring device (Quantachrome Monosorb) was used.

・Average particle size (D ₁ ) of elongated silica particles used as a raw material by dynamic light scattering method: An aqueous dispersion of silica particles is measured by a dynamic light scattering method particle size measurement device Zetasizer Nano (Spectris Co., Ltd. Malvern business (manufactured by Kobe Steel) was used.
・ Particle diameter (D ₂ ) measured by the nitrogen adsorption method of elongated silica particles used as raw materials: From the specific surface area S (m ² / g) measured by the nitrogen adsorption method as a spherical conversion diameter, the particle diameter by the nitrogen adsorption method (nm)=2727/S given by the formula.

[Synthesis of silica particles α-1 obtained in step (a)]
Commercially available elongated silica sol (manufactured by Nissan Chemical Co., Ltd., trade name Snowtex UP (SiO ₂ concentration 20.2% by mass, Na ₂ O concentration 0.27% by mass, pH 10.2, viscosity of B-type viscometer 15 .0 mPa s, conductivity 2590 μS/cm, particle diameter (D ₁ ) measured by dynamic light scattering method 52.7 nm, specific surface area 225 m ² /g measured by nitrogen gas adsorption method, particle diameter (D ₂ ) 12 nm) 1.5 kg was charged into a stainless steel container with a volume of 3 L, and the liquid temperature was heated to 75 ° C. while stirring with a propeller stirring blade.Then, the liquid temperature was controlled to 75 to 80 ° C., and the elongated shape 1 kg of silica sol was concentrated while adding it over 7 hours, and the SiO ₂ concentration was concentrated to 29.5% by mass to produce 1.7 kg of a silica sol concentrate having a viscosity of 1010 mPa s on a B-type viscometer.This silica sol concentrate After charging 855 g of the product into a plastic bottle with a volume of 2 L, after installing a saw blade impeller stirrer with a diameter of 75 mm, the liquid temperature is heated to 65 ° C. with a commercially available water bath while stirring at a rotation speed of 1000 rpm. After the liquid temperature reached 65° C., the rotational speed was increased to 5460 rpm and stirring with a high shearing force was started.The viscosity began to increase after stirring for 30 minutes, and increased significantly after stirring for 1 hour. After that, the viscosity gradually decreased, and the high shear force stirring was continued for 18 hours to obtain an alkaline aqueous silica sol containing porous agglomerated silica particles.The amount of the aqueous silica sol obtained was 800 g, and the _SiO2 concentration was 31. 0.5 mass %, pH 10.2, viscosity of 22 mPa·s by Brookfield viscometer, and average particle size (A ₂ ) of 150 nm by laser diffraction method.

Pure water was added to 800 g of the above alkaline aqueous silica sol to prepare _{an SiO} concentration of 20.0% by mass. After passing through a column packed with exchange resin Amberlite (registered trademark)-A410 at a space velocity of SV5, the solution was again passed through a column packed with cation exchange resin Amberlite (registered trademark)-120B at a space velocity of SV5, 1200 g of an aqueous silica sol (α-1) containing porous secondary aggregated silica particles as shown in Table 1 and FIG. 1 was obtained.

[Synthesis of silica particles α-2 of the present invention]
To 1000 g of the aqueous silica sol (α-1) was added a 10% by mass aqueous sodium hydroxide solution to obtain a SiO ₂ /Na ₂ O molar ratio of 105, a SiO ₂ concentration of 15.0% by mass, a pH of 10.0 and an electrical conductivity of 910 μS/. cm and Na ₂ O concentration of 1483 ppm, 280 g of the solution was taken, charged into a 300 ml stainless steel high-pressure vessel, and hydrothermally treated at 180° C. for 10 hours. This hydrothermal treatment operation was repeated three times to obtain 840 g of aqueous silica sol (α-2) containing silica particles forming a net as shown in Table 2 and FIG.

[Synthesis of silica particles β-1 obtained in step (a)]
Commercially available elongated silica sol (manufactured by Nissan Chemical Co., Ltd., trade name Snowtex UP (SiO ₂ concentration 20.2% by mass, Na ₂ O concentration 0.27% by mass, pH 10.2, viscosity of B-type viscometer 15 mPa・s, conductivity 2590 μS/cm, particle diameter (D ₁ ) measured by dynamic light scattering method 52.7 nm, specific surface area 225 m ² /g measured by nitrogen gas adsorption method, particle diameter (D ₂ ) measured by nitrogen adsorption method 12 nm ) was charged into a 700 L jacketed mixing tank (inner diameter 95 cm, height 100 cm), and the liquid temperature was heated to 75° C. while stirring with a propeller stirring blade. , While adding 191 kg of the elongated silica sol over 25 hours, it was concentrated to a SiO ₂ concentration of 27.6% by mass to produce 470 kg of a silica sol concentrate with a Brookfield viscosity of 970 mPa s. The silica sol concentrate was transparent with a slight colloidal color.

After 855 g of this silica sol concentrate was placed in a 2-liter plastic bottle, a saw blade impeller agitator with a diameter of 75 mm was installed, and the rotation speed was 1000 r.p.m. p. The temperature of the liquid was heated to 65°C in a commercially available water bath while stirring at 2,800 r.m. p. m and started high shear agitation. After stirring for 30 minutes, the viscosity began to increase, and after stirring for 1 hour, the viscosity increased significantly. After that, the viscosity gradually decreased, and the stirring with a high shear force was continued for 32 hours. A silica sol was obtained.
This aqueous silica sol was obtained in an amount of 805 g, a SiO ₂ concentration of 29.3% by mass, a pH of 10.2, a viscosity of 26 mPa·s on a Brookfield viscometer, and a milky white color. The average particle size (A ₂ ) measured by laser diffraction method was 270 nm. In addition, observation with a transmission electron microscope confirmed that the particles were substantially spherical aggregated silica particles in which elongated colloidal silica was entangled. The average primary particle size (A ₁ ) measured by transmission electron microscope observation was 330 nm.

Pure water was added to 800 g of the above alkaline aqueous silica sol to prepare _{an SiO} concentration of 20.0% by mass. After passing through a column packed with exchange resin Amberlite (registered trademark)-A410 at a space velocity of SV5, the solution was again passed through a column packed with cation exchange resin Amberlite (registered trademark)-120B at a space velocity of SV5, 1300 g of acidic aqueous silica sol (β-1) containing porous secondary aggregated silica particles as shown in Table 1 and FIG. 3 was obtained.

[Synthesis of silica particles β-2 of the present invention]
To 1000 g of the aqueous silica sol (β-1) was added pure water and a 10% by mass aqueous sodium hydroxide solution to obtain a SiO ₂ /Na ₂ O molar ratio of 89, a SiO ₂ concentration of 15.0% by mass, a pH of 10.2, and an electrical conductivity. After adjusting the temperature to 1110 μS/cm and the Na ₂ O concentration to 1745 ppm, 280 g of the solution was fractionated, placed in a 300 ml stainless steel high-pressure vessel, and hydrothermally treated at 180° C. for 10 hours. This hydrothermal treatment operation was repeated three times to obtain 840 g of aqueous silica sol (β-2) in which silica particles forming a network and silica particles not forming a network as shown in Table 2 and FIG. 4 were mixed.

[Synthesis of silica particles β-3 of the present invention]
Pure water was added to 300 g of the aqueous silica sol (β-1) to obtain a SiO ₂ /Na ₂ O molar ratio of 1070, a SiO ₂ concentration of 15.0% by mass, a pH of 3.8, an electrical conductivity of 96 μS/cm, and a Na ₂ O concentration. After adjusting to 145 ppm, 280 g was fractionated and charged into a 300 ml stainless steel high-pressure vessel and subjected to hydrothermal treatment at 220 ° C. for 5 hours to form the mesh shown in Table 2 and FIG. 5, but containing partially cut silica particles. 280 g of aqueous silica sol (β-3) mixed with

[Synthesis of silica particles β-4 of the present invention]
Pure water and 10% by mass aqueous sodium hydroxide solution were added to 300 g of aqueous silica sol (β-1) to adjust the molar ratio of SiO ₂ /Na ₂ O to 303, SiO ₂ concentration 15.0% by mass, pH 8.2, conductivity. After adjusting the concentration to 512 μS/cm and the Na ₂ O concentration to 512 ppm, 280 g was taken out and charged into a 300 ml stainless steel high-pressure vessel and subjected to hydrothermal treatment at 250 ° C. for 5 hours. 280 g of aqueous silica sol (β-4) containing mixed silica particles was obtained.

[Synthesis of silica particles γ-1 obtained in step (a)]
Commercially available elongated silica sol (manufactured by Nissan Chemical Co., Ltd., trade name Snowtex UP (SiO ₂ concentration 20.2% by mass, Na ₂ O concentration 0.27% by mass, pH 10.2, viscosity of B-type viscometer 20 mPa s, conductivity 2580 μS/cm, particle diameter (D ₁ ) measured by dynamic light scattering method 53.0 nm, specific surface area 224 m ² /g measured by nitrogen gas adsorption method, particle diameter (D ₂ ) measured by nitrogen adsorption method 12 nm ) was charged into a 700 L jacketed mixing tank (inner diameter 95 cm, height 100 cm), and the liquid temperature was heated to 75° C. while stirring with a propeller stirring blade. Then, 191 kg of the elongated silica sol was added and concentrated over 25 hours to a concentration of 28.6% by mass of SiO ₂ to produce 436 kg of concentrated silica sol having a B-type viscometer viscosity of 840 mPa s. The silica sol concentrate had a slight colloidal color but was transparent.349 kg of this silica sol concentrate and 1.6 kg of pure water were placed in a 700 L jacketed mixing tank (inner diameter: 95 cm, height: 100 cm).A saw with a diameter of 300 cm. A blade-shaped impeller stirrer was installed, and after heating at a rotation speed of 510 rpm and the liquid temperature reached 65° C., the rotation speed was increased to 1100 rpm and stirring with a high shear force was started for 30 minutes. After stirring, the viscosity began to increase, and when the viscosity increased significantly during stirring for 1 hour and 36 minutes, 70.7 kg of pure water was added to adjust the viscosity to 780 mPa s by a Brookfield viscometer. The viscosity gradually decreased, and stirring with a high shear force was continued for 27 hours to produce an alkaline aqueous silica sol exhibiting a milky white color with a _SiO concentration of 22.5% by mass, a pH of 10.2, and a B-type viscometer viscosity of 21 mPa s. Subsequently, 2 kg of this aqueous sol was put into a 3 L glass eggplant flask and concentrated under reduced pressure in a 60° C. hot water bath to contain porous secondary aggregated silica particles as shown in Table 1 and Photo 7. 2590 g of an alkaline aqueous silica sol (γ-1) was obtained _, and as shown in Table ₁ and _FIG . 0% by mass, pH 9.7, electrical conductivity 2960 μS/cm, Na ₂ O concentration 3510 ppm, average particle size (A ₂ ) measured by laser diffraction was 677 nm, and elongated colloidal particles were observed by transmission electron microscopy. Nearly spherical porous secondary agglomerated silica particles intertwined with silica observed to be a child. The average particle size (A ₁ ) measured by transmission electron microscope observation was 725 nm.

[Synthesis of silica particles γ-2 of the present invention]
280 g of alkaline aqueous silica sol (γ-1) was placed in a 300 ml stainless steel high-pressure vessel and subjected to hydrothermal treatment at 200° C. for 5 hours to obtain an aqueous silica sol containing silica particles forming a net as shown in Table 2 and FIG. 280 g of (γ-2) was obtained.
[Synthesis of silica particles γ-3 of the present invention]
280 g of alkaline aqueous silica sol (γ-1) was placed in a 300 ml stainless steel high-pressure container and subjected to hydrothermal treatment at 140° C. for 5 hours. It was not a silica particle with shells.

[Synthesis of Silica Particle γ-4 of Comparative Example]
280 g of alkaline aqueous silica sol (γ-1) was placed in a 300 ml stainless steel high-pressure vessel and hydrothermally treated at 280° C. for 5 hours. As shown in Table 2, the silica sol gelled and solidified into a hard agar. .
As shown in Table 1 and FIGS. 2, 4, 5, 6, and 8, the alkaline porous secondary aggregated silica aqueous sol was adjusted to a _SiO concentration of 10 to 30% by mass and a pH of 7 to 11. After that, by hydrothermally treating at 150 to 220 ° C. for 1 to 30 hours, only silica particles having a net-like shell are obtained, and the diameter of the silica component constituting the net-like shell is 20 to 90 nm. The average particle diameter (A ₂ ) measured by a laser diffraction method in which the area ratio of the through holes of the particles measured from the plane projection view of the microscope is 5% to 30% and the porosity of the particles is 30 to 90% It can be seen that silica particles (α-2), (β-2), (β-3), (β-4) and (γ-2) of 100 nm to 1.5 μm can be produced.

As shown in FIG. 5, although the silica particles of the present invention can be produced at a pH of 3.6, it is found that porous silica particles before the hydrothermal treatment are mixed.

In addition, as shown in FIG. 6, under the heat treatment condition of a hydrothermal temperature of 250° C., although the silica particles of the present invention can be produced, it is found that other silica particles with broken meshes are mixed.
As shown by the silica particles (γ-4) in Tables 1 and 2, when the hydrothermal temperature was 280° C. or higher, the silica sol gelled and the silica particles of the present invention could not be produced.

As a reference example, aqueous silica sol (solid silica particles δ-1 (MP-2040, FIG. 9) and δ-2 (MP-3040, FIG. 10) with no net-like outer shell and internal cavity were prepared (Nissan Chemical Co., Ltd.).
In the table below, (--) indicates unmeasured.

[Table 1]
Table 1
――――――――――――――――――――――――――――――――――――――――
Silica particles α-1 β-1 γ-1 δ-1 δ-2
SiO ₂ concentration mass % 16 18 26 40.5 40.7
Na ₂ O concentration ppm 136 175 3510 330 240
pH 3.1 2.9 9.7 9.4 9.7
Conductivity μS/cm 222 398 2960 ― ―
Specific surface area m ² /g 225 218 221 21 13
Average particle size (A ₂ ) nm 150 290 677 180 290
Average primary particle size (A ₁ ) nm 160 330 725 200 310
Centrifugal sedimentation average particle size nm 100 170 320 180 300
Silica particle density g/cm ³ 1.47 1.32 1.23 1.97 2.12
Silica particle porosity % 62 74 80 19 7
Percentage of through holes in silica particles 3 3 2 0 0
――――――――――――――――――――――――――――――――――――――――

[Table 2]
Table 2-1-1
――――――――――――――――――――――――――――――――――――――――
(Silica particles before hydrothermal treatment)
Silica particles α-2 β-2 β-3 β-4
SiO ₂ concentration Mass % 15 15 15 15
Na ₂ O concentration ppm 1483 1745 145 512
_SiO2 / _Na2O molar ratio 105 89 1070 303
pH 10.0 10.2 3.6 8.2
Conductivity μS/cm 910 1110 96 201
――――――――――――――――――――――――――――――――――――――――

[Table 3]
Table 2-1-2
――――――――――――――――――――――――――――――――――――――――
(Silica particles before hydrothermal treatment)
Silica particles γ-2 γ-3 γ-4
SiO ₂ concentration Mass % 26 26 26
Na ₂ O concentration ppm 3510 3510 3510
_SiO2 / _Na2O molar ratio 77 77 77
pH 9.7 9.7 9.7
Conductivity μS/cm 2960 2960 2960
――――――――――――――――――――――――――――――――――――――――

[Table 4]
Table 2-2-1
――――――――――――――――――――――――――――――――――――――――
(Silica particles after hydrothermal treatment)
Silica particles α-2 β-2 β-3 β-4
Hydrothermal conditions °C x hours 180 x 10 180 x 10 220 x 5 250 x 5
pH 10.8 11.0 8.5 10.3
Conductivity μS/cm 1960 2480 80 648
Specific surface area m ² /g 71 65 79 38
Diameter of mesh silica particles nm 26 28 ----
Average particle size (A ₂ ) nm 150 277 266 235
Average primary particle size (A ₁ ) nm 160 300 ---
Centrifugal sedimentation average particle size nm 100 170 ----
Silica particle density g/cm ³ 1.47 1.38 -- --
Porosity % of silica particles 62 68 ----
Percentage of through holes in silica particles 5 3 ----
――――――――――――――――――――――――――――――――――――――――

[Table 5]
Table 2-2-2
――――――――――――――――――――――――――――――――――――――――
(Silica particles after hydrothermal treatment)
Silica particles γ-2 γ-3 γ-4
Hydrothermal conditions °C x hours 200 x 5 140 x 5 280 x 5
pH 10.2 10.6 --
Conductivity μS/cm 4210 3060 ---
Specific surface area m ² /g 44 135 --
Net silica particle diameter nm 41 ----
Average particle size (A ₂ ) nm 670 635 --
Average primary particle size (A ₁ ) nm 720 720 --
Centrifugal sedimentation method average particle size nm 320 320 --
Silica particle density g/cm ³ 1.23 1.23 --
Porosity % of silica particles 81 80 ---
Percentage of through holes in silica particles 3 5 ---
――――――――――――――――――――――――――――――――――――――――

(Production Example 1: Organic solvent-dispersed silica sol-1)
The aqueous dispersion of silica particles obtained in Synthesis Example α-2 was passed through a column filled with cation exchange resin Amberlite (registered trademark)-120B to obtain a silica dispersion having a solid content of 20% by mass. 200 g of this acidic dispersion was placed in a 2 L eggplant-shaped flask, diluted with 800 g of isopropyl alcohol, then 2 g of trimethylmethoxysilane was added and heated at a bath temperature of 60° C. for 3 hours while stirring with a magnetic stirrer. After that, it was concentrated to 500 g with a rotary evaporator, and then gradually concentrated while adding 800 g of MEK to obtain 202 g of a silica dispersion in methyl ethyl ketone having a solid concentration of 20% by mass.

(Comparative Production Example 1: Organic solvent-dispersed silica sol-2)
240 g of the aqueous dispersion of porous secondary aggregated silica particles obtained in Synthesis Example α-1 was placed in a 2 L round-bottomed flask, diluted by adding 860 g of isopropyl alcohol, and then 4 g of trimethylmethoxysilane was added. It was heated at 60° C. for 3 hours while stirring with a magnetic stirrer. After that, it was concentrated to 500 g with a rotary evaporator, and then gradually concentrated while adding 800 g of MEK to obtain 204 g of a methyl ethyl ketone dispersion of silica having a solid concentration of 20% by mass.

(Comparative Production Example 2: Organic solvent-dispersed silica sol-3)
After diluting a commercially available solid silica sol (MP-2040 ( _SiO2 concentration 40.6% by mass, pH 9.4, manufactured by Nissan Chemical Co., Ltd.) with pure water to 10% by mass _SiO2 , a cation exchange resin column, Then, the solution was passed through an anion exchange resin column, and then passed through a cation exchange resin column again to obtain a silica dispersion having a solid content of 9.5% by mass. After concentrating to 200 g with a rotary evaporator, 800 g of isopropyl alcohol was added for dilution, 1 g of trimethylmethoxysilane was added, and the mixture was heated at a bath temperature of 60° C. for 3 hours while stirring with a magnetic stirrer. It was concentrated to 500 g and then gradually concentrated while adding 800 g of MEK to obtain 201 g of a silica dispersion in methyl ethyl ketone having a solid content of 20%.

(Production Example 2: Organic solvent-dispersed silica sol-4)
A dispersion of methyl ethyl ketone was obtained in the same manner as in Production Example 1 using the silica of Synthesis Example β-2 as a starting material.
(Production Example 3: Organic solvent-dispersed silica sol-5)
An MEK dispersion was obtained in the same manner as in Production Example 1 using the silica of Synthesis Example γ-2 as a starting material.

(Comparative Production Example 3: Organic solvent-dispersed silica sol-6)
A commercially available solid silica sol (MP-3040 (SiO ₂ concentration 40.8% by mass, pH 9.7, manufactured by Nissan Chemical Industries, Ltd.) was used as a starting material, and a methyl ethyl ketone dispersion was obtained in the same manner as in Production Example 3.
(Examples and Comparative Examples)
The silica methyl ethyl ketone dispersions of Production Examples 1-3 and Comparative Production Examples 1-3 were blended to prepare coating compositions shown in Tables 3-1 and 3-2. PGME (propylene glycol monomethyl ether) was used as the main solvent of the coating liquid.

The coating composition in Table 1 was applied to a PET film (Cosmo Shine A-4100, 125 μm) with a wire bar so that the film thickness after curing was 2.5 μm, dried on a hot plate at 50 ° C. for 3 minutes, and then exposed to ultraviolet light. It was cured to obtain a coated film. Curing was performed in air at 1000 mJ/cm ² using an ultraviolet lamp (metal halide lamp, manufactured by EYE GRAPHICS, trade name M04-L41, wavelength range 200 nm to 450 nm).

Comparative Example 4 is a PET film coated with a coating liquid containing no silica particles.

Evaluation of the coated film was performed as follows.

Haze: Measured in JIS K7105 mode using HAZE MATER NDH5000 (Nippon Denshoku).

Sliding property (tactile sensation): The coated surfaces were overlapped and strongly pinched from above and below with the index finger and thumb to examine the tactile sensation when moved. ⊚: Slips smoothly, ◯: Sliding with some resistance, △: Squeaks with strong resistance, ×: Sticks and does not move.

Static friction coefficient: Measured using a static friction coefficient measuring device HEIDON-10 (Shinto Kagaku). A silica-free coated film (Comparative Example 4) is set as a mount on the lower sliding surface (rising plate), and a flat indenter with the coated films of Examples 1 to 3 and Comparative Examples 1 to 4 attached is placed on it and raised. The plate was tilted and the static friction coefficient was obtained from the angle at which the terminal slid down.

Ra: Measured using an atomic force microscope Dimension Icon (Bruker).

The evaluation results of the coated films are shown in Tables 4-1 and 4-2.

Comparative Example 4, which is a PET film coated with a coating liquid containing no silica particles, has a low haze, but a large coefficient of static friction and poor sliding properties.

It can be seen that Examples 1, 2 and 3 (organic solvent-dispersed silica sol 1, 4 and 5) achieved both low haze and good slipperiness. Comparative Example 1 of porous secondary aggregated silica particles (organic solvent-dispersed silica sol 2) has a low haze, but the effect of slipperiness is insufficient. The solid particles of Comparative Examples 2 and 3 (organic solvent-dispersed silica sol 3 and 6) tend to have an increased haze and have insufficient slip properties.

In the table below, PGME (solvent) indicates propylene glycol monomethyl ether, DPHA (radical polymerizable monomer) indicates a mixture of dipentaerythritol penta- and hexaacrylates, and Irgacure 184 (photoradical generator) indicates α-hydroxycyclohexyl. It is a phenyl ketone and has the following structure.

The anionic surfactant used was the trade name PLYSURF A-212C (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., the component being a phosphate-based anionic surfactant). The following contents and concentrations are shown in % by mass.

[Table 6]
Table 3-1
――――――――――――――――――――――――――――――――――――――――
Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 4
Organic solvent-dispersed silica sol 1 2 3 -
_SiO2 concentration 0.95 0.95 0.95 0
DPHA concentration 18.87 18.87 18.87 19.05
Irgacure 184 0.94 0.94 0.94 0.95
Anionic surfactant 0 0 0 0
――――――――――――――――――――――――――――――――――――――――

[Table 7]
Table 3-2
――――――――――――――――――――――――――――――――――――――――
Example 2 Example 3 Comparative example 3
Organic solvent dispersed silica sol 4 5 6
_SiO2 concentration 0.95 0.95 0.95
DPHA concentration 18.87 18.87 18.87
Irgacure 184 0.94 0.94 0.94
Anionic surfactant 0.05 0.05 0.05
――――――――――――――――――――――――――――――――――――――――

[Table 8]
Table 4-1
――――――――――――――――――――――――――――――――――――――――
Example Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 4
Silica compounding amount/resin 5 phr 5 phr 5 phr 0 phr
Haze 0.49 0.41 0.65 0.45
Slipperiness 〇 △ × ×
Static friction coefficient 0.47 1.19 1.6 or more 1.6 or more Paint film Ra (nm) 5.5 0.9 0.5 0.4
――――――――――――――――――――――――――――――――――――――――

[Table 9]
Table 4-2
――――――――――――――――――――――――――――――――――――――――
Example Example 2 Example 3 Comparative example 3
Silica compounding amount/resin 5 phr 5 phr 5 phr
Haze 0.60 0.49 1.19
Slipperiness ◎ 〇 △
Static friction coefficient 0.31 0.86 1.60
Coating film Ra (nm) 7.4 1.4 2.7
――――――――――――――――――――――――――――――――――――――――
In addition, a photocurable resin containing silica particles α-2 having a net-like outer shell is photocured, the cross section of the cured resin is cut, and the cross section is observed with an electron microscope (FIG. 11). is an internal space (cavity).

The present invention is a particle mainly composed of silica having a net-like outer shell and an inner space, and having through-holes leading from the inner space to the outer shell. To provide silica particles capable of containing various components and media inside the cavity by utilizing the cavity, and a method for producing the internal space.

Claims (9)

Particles mainly composed of silica having a net-like outer shell and an inner space, and having through-holes connecting the inner space to the outer shell, wherein the diameter of the net is 20 nm to 90 nm, and the porosity in the particle is 30. 90% silica particles having an average particle size (A ₂ ) of 100 nm to 1.5 μm as measured by a laser diffraction method. The average primary particle size (A ₁ ) observed with a transmission electron microscope is 100 nm to 1.5 μm, and the ratio of average particle size (A ₂ )/average primary particle size (A ₁ ) is 0.8 to 1.5 μm. 5. The silica particles according to claim 1. 3. The silica particles according to claim 1 or 2, having a specific surface area of 20 to 90 m ² /g as measured by a nitrogen gas adsorption method. The silica particles according to any one of claims 1 to 3 are dispersed in an acidic or alkaline aqueous medium or organic solvent, and the average particle diameter (A ₂ ) measured by laser diffraction is 100 nm to 1. A silica sol that is 0.5 μm. 5. The method for producing a silica sol according to claim 4, comprising the following steps (a) to (b).
(a) step: the ratio D ₁ /D ₂ of the particle diameter (D ₁ ) measured by the dynamic light scattering method and the particle diameter (D ₂ ) measured by the nitrogen gas adsorption method is 4 to 10, and D ₁ is 40 ~ 200 nm, D ₂ of 8-30 nm, colloidal silica with a SiO ₂ concentration of 21-30 wt. a step of producing an alkaline porous secondary aggregate silica aqueous sol having an average particle size of 100 nm to 1.5 μm and a specific surface area of 90 to 350 m ² /g as measured by a nitrogen gas adsorption method;
(b) step: SiO ₂ /Na ₂ O molar ratio of 30 to 3000, SiO ₂ concentration of 0.1 to 30% by mass, pH adjusted to 3 to 11, and then at a temperature above 100° C. and below 270° C. A step of hydrothermally treating for 1 to 30 hours. A method for producing an organosilica sol, wherein after the step (b) according to claim 5, the step of replacing the aqueous medium with an organic solvent is performed. A film-forming composition comprising the silica particles according to any one of claims 1 to 4 and a resin. 8. The film-forming composition according to claim 7, wherein the resin is a photocurable resin or a thermosetting resin. A film formed from the film-forming composition of claim 7 or claim 8.

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