TW202114941A - Particles with hollow inside outer-shell containing silica,production method of same, coating liquid containing same, and substrate with transparent coat containing same - Google Patents

Abstract

The present invention provides a coating liquid capable of obtaining a transparent film having excellent adhesion to a substrate, a high hardness and a high strength. Particles contained in the coating liquid have a dense shell containing silicon dioxide and define cavities inside the shell. The average particle diameter (D) of the particles is 20 to 250nm. The diameter of the cavity is 0.5 to 0.9 times of the diameter of the particle. The pore volume of the particles by the N2 adsorption method is less than 1.0 cubic centimeter/g and the refractive index (na) of the particles is 1.08 to 1.34. The refractive index (nS) of the shell obtained by formula (1) is 1.38 or more. The substrate having the transparent film by coating with the coating liquid has a high hardness and a high strength, and is particularly useful for preventing reflection.

Description

Particles with cavities on the inside of the casing, method for producing the same, coating liquid containing them, and base material with transparent coating film containing them

The present invention relates to a particle having a cavity inside a shell containing silicon dioxide and a method of manufacturing the particle. In addition, the present invention relates to a coating liquid for forming a transparent film containing the particles and a substrate with a transparent film containing the particles.

In the past, in order to prevent reflection on the surface of a substrate such as a sheet or lens made of glass, plastic, or the like, an anti-reflection film was formed on the surface. For example, a coating film of a low-refractive index substance such as fluororesin or magnesium fluoride is formed on the surface of a glass or plastic substrate by a coating method, a vapor deposition method, or a CVD method. However, these methods are expensive in terms of cost. In this regard, the following method is known (for example, refer to Japanese Patent Laid-Open Publication No. 7-133105). In this method, a coating solution containing colloidal composite oxide particles composed of silica and inorganic oxides other than silica having a refractive index of 1.36 to 1.44 is applied to the surface of the substrate, thereby forming Anti-reflection coating.

In addition, a method for producing porous hollow particles is known (for example, refer to Japanese Patent Laid-Open No. 2001-233611). The hollow particles obtained by this method have a low refractive index. The transparent coating formed using the hollow particles has a low refractive index and is excellent in anti-reflection performance.

In addition, it is known that if a transparent coating containing hollow particles is provided on the front surface of a display device, the anti-reflection performance of the display device can be improved and its display performance can be improved (for example, refer to Japanese Patent Laid-Open No. 2002-079616).

However, if silicon dioxide-based particles having a cavity inside are used for an anti-reflection film, the hardness and strength (scratch resistance) of the obtained film may decrease. In addition, if the particles are excessively hollowed in order to reduce the refractive index of the particles, the particles themselves become brittle. Therefore, the hardness or strength (scratch resistance) of the transparent film formed using the particles also becomes insufficient.

In this way, if the hardness and strength of the particles are insufficient, there is a problem that at least one of the refractive index, hardness, and strength of the transparent coating becomes insufficient.

In order to solve such a problem, the following particles having a shell containing silicon dioxide and a cavity inside the shell are applied to the coating liquid for forming a transparent film. The average particle size (D) of the particles is 20-250nm, the diameter of the cavity is 0.5-0.9 times the particle diameter, _{and the pore volume by the N 2} adsorption method is less than 1.0 cm ³ /g, which can be calculated by the following formula (1) The refractive index (n _s ) of the shell is 1.38 or more, the refractive index (n _a ) is 1.08 to 1.34, and the carbon content is 3.0% by mass or less.

[Math 1]

D is the average particle size, D ₀ is the average diameter of the voids inside the housing, n _a is the refractive index of particles, n _p is the refractive index of the cavity.

The particles have cavities on the inside of a dense shell containing silicon dioxide. Therefore, the particles have sufficient hardness and strength and low refractive index. If it is a coating liquid containing such particles, a substrate with a transparent film having high hardness (pencil hardness) and high strength (scratch resistance) can be obtained.

According to the particles of the present invention, a coating liquid capable of producing the following transparent film can be obtained. The transparent film has low reflectivity, excellent adhesion to the substrate, and high hardness and strength.

The particle according to this embodiment is a particle having a shell containing silicon dioxide and a cavity inside the shell (hereinafter, the particle according to this embodiment may be simply referred to as a particle). The cross section of the particle is schematically shown in FIG. 1.

The average particle diameter D of the particles is 20 to 250 nm. If the average particle diameter is in this range, the particles can exist stably. In addition, if the average particle size is in this range, the particles have high dispersibility even in the coating liquid and the film, and high transparency, hardness, and strength of the film can be obtained. The average particle diameter is preferably 30 to 150 nm, more preferably 30 to 120 nm.

The diameter of the cavity inside the shell is a length of 0.5 to 0.9 times the diameter (outer diameter) of the particle. If the diameter of the cavity is in this range, the structure of the shell can be stably maintained, and therefore the particles can exist stably. In addition, high transparency, hardness, and strength of the film can be obtained. Here, if the diameter of the cavity inside the outer shell is smaller than 0.5 times the diameter (outer diameter) of the particles, the thickness of the outer shell may be too thick, and sufficient transparency of the film may not be obtained. If the diameter of the cavity inside the shell is greater than 0.9 times the diameter (outer diameter) of the particles, the shell may become thin and it may become difficult to maintain the particle structure. The diameter of the cavity is preferably 0.55 to 0.9 times the diameter of the particles, and more preferably 0.6 to 0.85 times.

The pore volume of the particles by the N ₂ adsorption method is less than 1.0 cm ³ /g. If the pore volume is in this range, the structure of the casing is dense. If the pore volume is greater than 1.0 cm ³ /g, the structure of the casing is loose (porous), and the hardness and strength of the casing become weak. Therefore, there is a possibility that it is difficult to maintain the structure of the housing and sufficient hardness and strength of the film cannot be obtained. The pore volume is preferably less than 0.8 cm ³ /g, more preferably less than 0.5 cm ³ /g, and most preferably 0.0 cm ³ /g.

N _a refractive index of the particles is 1.08 to 1.34. If the refractive index is in this range, a transparent film can be obtained. The refractive index is preferably 1.08 to 1.32, more preferably 1.08 to 1.30.

The refractive index n _S of the casing is 1.38 or more. If the refractive index nS is 1.38 or more, the shell is dense. The upper limit of the refractive index n _S is not specifically set, but is 1.47, for example. The formula (1), the average particle diameter D of the inner cavity of the housing of the average diameter D _O, n _a refractive index particles and the refractive index of cavity n _P, the refractive index is obtained n _S. The refractive index n _P of the cavity differs depending on the state inside the cavity. For example, if the inside of the cavity is gas, the refractive index of the cavity becomes 1.00. In addition, if the inside of the cavity is a liquid, the refractive index of the cavity becomes the refractive index of the liquid.

If the refractive index n _{S is} in this range, a transparent film having sufficient hardness and strength can be obtained. If the refractive index n _{S is} less than 1.38, the hardness of the coating film may become insufficient. The refractive index n _S is preferably 1.40 or more, more preferably 1.42 or more.

The carbon content of the particles is 3.0% by mass or less. The carbon contained in the particles is derived from organic compounds such as organosilicon compounds, metal salts, reducing agents, pH adjusters, cleaning fluids, and solvents. Among them, in addition to substances that are intentionally added for the production of particles, substances that are unavoidably present in raw materials and the like are also included. If organic compounds are contained in the particles, the hardness and strength of the outer shell will be weakened. Therefore, when the particles are used to form a film, the transparency of the film decreases or the dispersibility of the film decreases. Therefore, it may not be possible to obtain a transparent film having sufficient hardness and strength. As described later, the carbon content derived from such organic substances can be determined by analyzing the amount of C (carbon). The carbon content is preferably 1.0% by mass or less, more preferably 0.1% by mass or less, and still more preferably 0.05% by mass or less.

For the ²⁹ _{Si-NMR spectroscopy of particles, the area Q 1} of the peak appearing at chemical shift -78 to _{-88 ppm, the area Q 2} of the peak appearing at chemical shift -88 to -98 ppm, and the peak appearing at chemical shift -98 to- The area Q _{3 of the peak appearing at 108 ppm and the area Q 4} of the peak appearing at chemical shifts -108 to -117 ppm are preferably ratio (Q ₁ /ΣQ) substantially 0 and ratio (Q ₂ /ΣQ) substantially 0, And the ratio (Q ₃ /Q ₄ ) is 0.01 to 0.7. Here, ΣQ=Q ₁ +Q ₂ +Q ₃ +Q ₄ .

This peak belonging to Q _{1 is} a peak related to the structure obtained by bonding one (-OSi) group and three (-OH) groups to the Si atom. The peak belonging to Q _{2 is} a peak related to the structure obtained by bonding two (-OSi) groups and two (-OH) groups to Si atoms. The peak belonging to Q _{3 is} a peak related to the structure obtained by bonding three (-OSi) groups and one (-OH) group to Si atoms. The peak belonging to Q _{4 is} a peak related to the structure obtained by bonding four (-OSi) groups to Si atoms.

Here, the ratio (Q ₁ /ΣQ) and the ratio (Q ₂ /ΣQ) being substantially 0 means that the peak can be inevitably detected due to the detection limit and noise in the measurement, for example, even if Taking these into consideration, it is also judged that the above-mentioned ratio is "0". Specifically, both of the ratios obtained by the above formula are 0.0001 or less. If the ratio (Q ₁ /ΣQ) and the ratio (Q ₂ /ΣQ) are substantially 0 and the ratio (Q ₃ /Q ₄ ) is 0.01 to 0.7, the particles are dense and transparent with sufficient hardness and strength can be obtained Envelope. If the ratio (Q ₁ /ΣQ) or the ratio (Q ₂ /ΣQ) is greater than 0.0001, since the ratio of Si-O-Si bonds is small, the hardness and strength of the film may become insufficient.

A structure with a ratio (Q ₃ /Q ₄ ) less than 0.01 is difficult to obtain. If the ratio (Q ₃ /Q ₄ ) is greater than 0.7, since the ratio of Si-O-Si bonds is small, the hardness of the film may become insufficient. The ratio (Q ₃ /Q ₄ ) is more preferably 0.02 to 0.5, and still more preferably 0.03 to 0.2.

The content of each element that is an alkali metal as an impurity of the particles, when the element is represented by an oxide, is preferably 1 ppm or less _{with respect to SiO 2.} If the content is in this range, the coalescence of particles decreases. Therefore, the particles are uniformly dispersed in the coating liquid and in the film. Therefore, a transparent film can be obtained. In addition, the performance of the coating liquid also increases the stability of the coating liquid. Regarding the performance of the film, the film hardness of the film also increases, and the transparency of the film also increases. Therefore, it is preferable that the content of the alkali metal element is in the above-mentioned range. Here, if the content of the alkali metal element is more than 1 ppm, the coalescence of particles increases. Therefore, there is a possibility that the hardness of the film becomes insufficient, or the transparency of the film becomes insufficient. The content of the alkali metal element is more preferably 0.1 ppm or less. Here, the alkali metal includes Li, Na, K, Rb, Cs, and Fr.

In addition, the respective contents of Fe, Ti, Zn, Pd, Ag, Mn, Co, Mo, Sn, Al, and Zr as impurities in the particles are preferably less than 0.1 ppm, and the respective contents of Cu, Ni and Cr as impurities in the particles are preferably It is less than 1 ppb, and the respective contents of U and Th as impurities of the particles are preferably less than 0.3 ppb. If the content of these impurities is in the above-mentioned range, a transparent film can be obtained, which is preferable. If the content of these impurities increases, the dispersion liquid will be colored, so there is a possibility that a transparent film cannot be obtained. In addition, when a coating liquid formed using particles with a high content of impurities is used in semiconductor circuits such as logic and memory and optical sensors that require high purity and high integration, metal elements can cause poor insulation of the circuit. Or short circuit the circuit, or reduce the light transmittance. As a result, the dielectric constant of the insulating film may decrease, the impedance of the metal wiring may increase, the response speed may be delayed, and the power consumption may increase. In particular, U and Th generate radioactivity. Therefore, since these elements cause a malfunction of the semiconductor due to radioactivity, even trace amounts of U and Th are undesirable.

In order to obtain particles with a low content of such impurity elements, it is preferable that the material of the device used in the preparation of the particles is a material that does not contain these elements and has high drug resistance. Specifically, the material is preferably plastic such as Teflon (registered trademark), FRP, carbon fiber, and alkali-free glass. In addition, the raw materials used are preferably purified by distillation, ion exchange, or filter removal.

As described above, as a method of obtaining high-purity particles, there are a method of preparing a raw material with few impurities in advance and a method of suppressing the incorporation of impurities from an apparatus for preparing particles. In addition to this, it is also possible to reduce impurities in particles prepared inadequately using such countermeasures.

The shape of the particle and the shape of the cavity of the particle are not particularly limited. Examples of their shapes include a spherical shape, an ellipsoid (rugby ball) shape, a cocoon shape, a candy shape, a chain shape, and a dice shape. Here, in order to be uniformly dispersed in the transparent film, the particle shape is preferably spherical. The shape of the cavity is preferably along the shape of the particle. Although it also depends on the thickness of the shell, even when stress is applied to the particles, by making the shell have a uniform thickness, the particles can maintain sufficient hardness and strength. In addition, the cavity is preferably a spherical shape similar to the shape of the spherical particle.

In addition, in order to reduce the refractive index and obtain a transparent coating, it is preferable that the void of the particles is substantially one void. Here, the particles may include "particles with multiple cavities inside the shell" due to coalescence of particles or the like. "The cavity of a particle is essentially one cavity" means that "the proportion of particles with one cavity inside the shell" is 90% or more. The "ratio of the number of particles having one cavity inside the shell" is preferably 95% or more, more preferably 98% or more, still more preferably 99% or more, and most preferably 100%.

The particles preferably contain 90% by mass or more of the silicon component as silicon dioxide. If the silicon component is in this range, the compatibility of the particles and the matrix forming component can be improved. Therefore, the particles are highly dispersed in the transparent film, and the strength and hardness of the film can be improved. The content of the silicon component is more preferably 95% by mass or more as silicon dioxide, still more preferably 98% by mass or more, and particularly preferably 100% by mass.

[Method of manufacturing particles]

The manufacturing method of this embodiment includes: the first process, when the oxide of silicon is expressed as SiO ₂ and the oxide of inorganic elements other than silicon is expressed as MO _x , the molar ratio (MO _x /SiO ₂ ) In a method of 0.01-2, a solution of a compound containing silicon and an aqueous solution of a compound of an inorganic element other than alkali-soluble silicon are simultaneously added to the alkaline aqueous solution to prepare a dispersion of composite oxide particles a; the second process , In such a way that the molar ratio (MO _x /SiO ₂ ) is smaller than the molar ratio of the first process, a solution of a compound containing silicon and an aqueous solution of a compound of an inorganic element other than alkali-soluble silicon are added to the composite In the dispersion liquid of oxide particles a, a dispersion liquid of composite oxide particles b is thus prepared; in the third process, an acid is added to the dispersion liquid of composite oxide particles b to remove the silicon other than the silicon constituting the composite oxide particles b. At least a part of the elements to prepare a dispersion of silica-based particles; and the fourth process, heating the dispersion of silica-based particles to 200-800°C at a temperature rise rate of 0.3-3.0°C/min, to 0.04 The temperature is lowered at a rate of -2.0°C/min., so that the dispersion liquid becomes 100°C or less. If necessary, silicon dioxide-based particles can also be cleaned.

Each process will be described in detail below.

[First Process]

Through the first process, a dispersion liquid of composite oxide particles a with an average particle diameter of 10-225 nm is prepared. The compound containing silicon is at least one selected from silicate, acid silicic acid liquid, and organosilicon compound.

As the silicate, one or two or more silicates selected from alkali metal silicates, ammonium silicates, and organic base silicates are preferred. Examples of alkali metal silicates include sodium silicate (water glass) and potassium silicate. Examples of organic bases include quaternary ammonium salts such as tetraethylammonium salt and amines such as monoethanolamine, diethanolamine, and triethanolamine. Ammonium silicate or organic base silicate also includes an alkaline solution obtained by adding ammonia, a quaternary ammonium hydroxide, or an amine compound to a silicic acid solution.

As the acidic silicic acid liquid, a silicic acid liquid obtained by removing an alkali from an alkaline silicate aqueous solution by treating an alkaline silicate aqueous solution with a cation exchange resin or the like can be used. Particularly preferred is an acidic silicic acid solution having a pH of 2 to 4 and an SiO ₂ concentration of about 7 mass% or less.

As the organosilicon compound, an organosilicon compound of the following formula (2) is preferred.

R _n -SiX _4-n・・・（2）

However, in the formula, R is an unsubstituted or substituted hydrocarbon group having 1 to 10 carbons, and may be the same or different from each other. Examples of the substituent include an epoxy group, an alkoxy group, a (meth)acryloxy group, a mercapto group, a halogen atom, an amino group, and a phenylamino group. X is an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, a halogen atom, or a hydrogen atom. n represents an integer of 0-3.

However, among the organosilicon compounds of formula (2), compounds with n being 1 to 3 lack hydrophilicity. Therefore, when the compound is used, it is preferable that the reaction system can be uniformly mixed by hydrolyzing the compound in advance. A well-known method can be used for the hydrolysis. As the hydrolysis catalyst, basic catalysts such as alkali metal hydroxides, ammonia water, and amines can be used. In this case, an acidic solution obtained by removing these basic catalysts after hydrolysis can also be used. In addition, acidic catalysts such as organic acids and inorganic acids can also be used to prepare the hydrolyzate. In this case, it is preferable to remove the acidic catalyst by ion exchange or the like after the hydrolysis. In addition, the obtained hydrolyzate of the organosilicon compound is preferably used in the form of an aqueous solution. Here, the term “aqueous solution” means a solution in which the hydrolyzate is not in a state of being cloudy and transparent as a gel.

Specifically, as the organosilicon compound, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, and phenyltrimethylsilane can be mentioned. Oxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyl Trimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, 3,3,3-trifluoropropyltrimethoxysilane, Methyl-3,3,3-trifluoropropyldimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxytripropyltrimethoxysilane Silane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxy Yl silane, γ-methacryloxy propyl trimethoxy silane, γ-methacryloxy propyl methyl diethoxy silane, γ-methacryloxy propyl triethoxy Silane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β -(Aminoethyl)-γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-amine Propyl trimethoxysilane, γ-mercaptopropyl trimethoxysilane, trimethylsilanol, methyltrichlorosilane, methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, benzene Trichlorosilane, diphenyldichlorosilane, vinyltrichlorosilane, trimethylbromosilane, diethylsilane, etc.

_{Examples of oxides (MO x} ) of inorganic elements other than silicon include Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , CeO ₂ , P ₂ O ₅ , Sb ₂ O ₃ , MoO _3. One or two or more of ZnO ₂ and WO _{3 etc.} In addition, examples of composite oxides of these inorganic elements other than silicon include TiO ₂ -Al ₂ O ₃ , TiO ₂ -ZrO _2, and the like.

As a raw material of such an inorganic oxide, an alkali-soluble inorganic compound is preferable. For example, examples of the raw material include metal or non-metal oxyacids, alkali metal or alkaline earth metal salts, ammonium salts, and quaternary ammonium salts that constitute oxides of inorganic elements other than silicon. Specifically, as the raw material, sodium aluminate, sodium tetraborate, ammonium zirconium carbonate, potassium antimonate, potassium stannate, sodium aluminosilicate, sodium molybdate, ammonium cerium nitrate, sodium phosphate, and the like are suitable.

In order to prepare a dispersion liquid of the composite oxide particles a, an alkaline aqueous solution of a compound of an inorganic element other than silicon is separately prepared in advance, or a mixed aqueous solution is prepared. According to the target compound ratio of silicon oxide (SiO ₂ ) and inorganic element oxides (MO _x ) other than silicon, the aqueous solution is gradually added to the alkaline aqueous solution while stirring. The alkaline aqueous solution is preferably adjusted to pH 10 or higher. It can be added continuously or intermittently. In addition, it is preferable to add both at the same time.

Regarding the addition ratio of the compound containing silicon to the compound of inorganic element other than silicon added to the alkaline aqueous solution, when the oxide of silicon of the compound containing silicon is expressed as SiO ₂ , the oxide of inorganic element other than silicon is expressed In the case of MO _x , the molar ratio (MO _x /SiO ₂ ) is 0.01-2. If the molar ratio is in this range, the structure of the composite oxide particles is mainly a structure in which silicon and an element other than silicon are bonded to each other through oxygen. That is, a structure in which a large number of oxygen atoms are bonded to the four bonding sites of silicon atoms and an element M other than silicon is bonded to the oxygen atoms is generated. As a result, when the element M other than silicon is removed in the third process described later, damage to the shape of the composite oxide particles can be suppressed, and silicon atoms can also be removed as a silicic acid monomer or oligomer with the element M. . Here, if the above-mentioned molar ratio is less than 0.01, it is difficult to sufficiently increase the void volume of the finally obtained particles. If the above-mentioned molar ratio is greater than 2, when elements other than silicon are removed in the third process, there is a possibility that the composite oxide particles will be destroyed, so it is difficult to obtain particles with voids inside the shell. The above-mentioned molar ratio is preferably 0.1 to 1.5. In addition, it is also possible to perform addition while changing the molar ratio so as to gradually decrease. It is preferable to perform the preparation so that the average particle diameter (Da) of the composite oxide particles after addition becomes approximately 10 to 225 nm (hereinafter, the composite oxide particles at this time may be referred to as primary particles).

However, even if the molar ratio is in the above-mentioned range, when the average particle diameter of the primary particles is less than 10 nm, the outer shell of the finally obtained particle becomes thicker, and therefore, it is difficult to sufficiently increase the void volume of the particle. In addition, if the average particle diameter of the primary particles exceeds 225 nm, the removal of the element M other than silicon in the third process described later becomes insufficient. Therefore, it is difficult to sufficiently increase the void volume of the particles, and it becomes difficult to obtain particles with a low refractive index.

In the production method of this embodiment, when preparing the dispersion liquid of the composite oxide particles a, the dispersion liquid containing the seed particles may be used as a starting material. In this case, as the seed particles, one kind or two or more kinds of particles such _{as SiO 2} , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO _2, and CeO _{2 can be cited.} In addition, examples of composite oxides include SiO ₂ -Al ₂ O ₃ , TiO ₂ -Al ₂ O ₃ , TiO ₂ -ZrO ₂ , SiO ₂ -TiO ₂ and SiO ₂ -TiO ₂ -Al ₂ O ₃ . particle. As the dispersion liquid containing the seed particles, a sol of these seed particles can usually be used. Such seed particles can be prepared by well-known methods. For example, the above-mentioned seed particles can be obtained by hydrolyzing a metal salt, a mixture of metal salts, or a metal alkoxide corresponding to the above-mentioned inorganic oxide by adding an acid or a base and aging as necessary.

In the same manner as the method of adding to the above-mentioned alkaline aqueous solution, the above-mentioned silicon-containing compound solution and an aqueous solution of a compound of an inorganic element other than alkali-soluble silicon are added to the seed particle-dispersed alkaline aqueous solution. At this time, it is preferable to adjust the pH of the seed particle dispersion alkaline aqueous solution to 10 or more.

In this way, if the seed particles are used as seeds to grow the composite oxide particles, it is easy to control the particle size of the grown particles. Therefore, particles with uniform particle size can be obtained. The addition ratio of the solution of the silicon-containing compound added to the seed particle dispersion to the aqueous solution of the alkali-soluble compound of the inorganic element other than the silicon is the same as the above-mentioned addition to the alkaline aqueous solution The same range. _{However, the molar ratio (MO x} /SiO ₂ ) of the additive liquid is calculated by subtracting the part of the seed particles.

Compounds containing silicon and compounds of inorganic elements other than silicon have high solubility on the alkaline side. However, if the two are mixed in this high-solubility pH region, the solubility of oxo acid ions such as silicate ions and aluminate ions decreases. Therefore, the oxyacid ion-containing complex precipitates and grows into colloidal particles, or the oxyacid ion-containing complex precipitates on the seed particles, and particle growth occurs.

[Second Process]

Next, a solution of a compound containing silicon and an aqueous solution of a compound of an inorganic element other than alkali-soluble silicon are added to the composite oxide particles at _{a molar ratio (MO x} /SiO ₂ ) smaller than that of the first process. In the dispersion liquid of a, a dispersion liquid of the composite oxide particles b is thus prepared. Thus, the composite oxide particles a (primary particles) are grown. It is preferable to perform preparation so that the average particle diameter Db of the composite oxide particle b after addition may become 20-250 nm.

From the materials exemplified in the first process, a compound containing silicon and a compound of an inorganic element other than alkali-soluble silicon used in the second process are selected. These compounds may be the same types of compounds as those used in the first process, or may be other types of compounds exemplified in the first process.

If the molar ratio (MO _x / SiO ₂₎ of the first process is set to A, the molar ratio of (MO _x / SiO ₂₎ is set to a second process B, then preferably less than 1 ratio B / A. If the ratio B/A is less than 1, the surface layer of the composite oxide particles is rich in silicon dioxide, and the formation of the outer shell becomes easy. As a result, in the third process described later, even if elements other than silicon are removed, the shape of the composite oxide particles is hard to be destroyed. Therefore, it is possible to stably obtain particles having voids inside the shell containing silicon dioxide. If the ratio B/A is 1 or more, it is difficult to produce a shell with a large amount of silicon dioxide. Therefore, when elements other than silicon are removed in the third process, the composite oxide particles may be destroyed and the particle shape may not be maintained. Therefore, it may not be possible to obtain particles having voids inside the shell containing silicon dioxide. The ratio B/A is more preferably 0.8 or less, and even more preferably 0.7 or less.

The ratio (Da/Db) of the average particle diameter Da of the composite oxide particles a (primary particles) to the average particle diameter Db of the composite oxide particles b obtained by particle growth (Da/Db) is preferably 0.5 to 0.9. When the ratio (Da/Db) is less than 0.5, there is a possibility that the removal of elements other than silicon in the third process becomes insufficient, and the void volume of the obtained particles is difficult to sufficiently increase, and it is difficult to obtain a low refractive index. particle of. In addition, if the ratio (Da/Db) is greater than 0.9, the particle size (specifically, composite oxide particles with an average particle size (Db) of less than 20 nm) may not be obtained inside the shell containing silicon dioxide. Particles with holes. The ratio (Da/Db) is more preferably 0.6 to 0.88, and still more preferably 0.7 to 0.85.

In the second process, an electrolyte salt can also be added to the dispersion of composite oxide particles a with an average particle diameter Da of approximately 10 to 225 nm.

Here, specifically, as the electrolyte salt, water-soluble electrolyte salts such as sodium chloride, potassium chloride, sodium nitrate, potassium nitrate, sodium sulfate, potassium sulfate, ammonium nitrate, ammonium sulfate, magnesium chloride, and magnesium nitrate can be cited. .

By adding electrolyte salt, when elements other than silicon are removed in the third process, it becomes easy to form a shell. The mechanism for obtaining such an effect is still unclear. In this regard, it can be considered that the silicon dioxide on the surface of the composite oxide particles after particle growth increases, and the silicon dioxide that is insoluble in acid acts as a protective film for the composite oxide particles.

The addition amount of the electrolyte salt, and when the number of moles of the electrolyte salt is represented by M _E, comprising a silicon compound to be used in the second manufacturing process expressed as M _S represents ₂ when the number of moles of SiO compound, the ratio of (M _E /M _S ) is preferably 0.1-10. If the ratio (M _E /M _S ) is less than 0.1, it becomes difficult to sufficiently realize the effect of adding the electrolyte salt. When the ratio (M _E /M _S ) is greater than 10, it is also difficult to improve the effect of adding the electrolyte salt. In addition, perhaps because the electrolyte salt acts as a buffer, there is a possibility that the particle growth in the second process is impaired, or the removal of elements other than silicon in the third process takes more time, or the economy is reduced. The ratio (M _E /M _S ) is more preferably 0.2-8. In addition, the full amount of electrolyte salt can also be added at the beginning of the second process. Alternatively, when adding a solution of a compound containing silicon and an aqueous solution of a compound of an inorganic element other than alkali-soluble silicon, the electrolyte salt may be added continuously or intermittently.

[The third process]

In the third process, an acid is added to the dispersion of composite oxide particles b to remove at least a part of the elements other than silicon constituting composite oxide particles b, thereby preparing a dispersion of silica-based particles. In the removal of elements, for example, dissolution removal using mineral acid or organic acid, ion exchange removal in which a cation exchange resin is brought into contact with the element, or a combination of these methods are used.

The concentration of the dispersion liquid of the composite oxide particles b varies depending on the treatment temperature, but it is preferable to convert the composite oxide particles b into an oxide of 0.1 to 50% by mass. Here, if the concentration is less than 0.1% by mass, the dissolved amount of silicon dioxide increases, and therefore it may become difficult to maintain the shape of the composite oxide particles. In addition, since the dispersion of the composite oxide particles b has a low concentration, the processing efficiency becomes low. If the concentration is higher than 50% by mass, the dispersibility of the particles becomes insufficient. In particular, it may become difficult to remove elements other than silicon uniformly or efficiently in composite oxide particles with a large content of elements other than silicon. The concentration of the dispersion liquid of the composite oxide particles b is more preferably 0.5 to 25% by mass.

The removal of the aforementioned elements is preferably carried out until the molar ratio (MO _x /SiO ₂ ) of the obtained silica-based particles becomes 0.2 or less. If the molar ratio (MO _x /SiO ₂ ) is greater than 0.2, the refractive index, the hardness, and the strength of the finally obtained "particles having a cavity inside the shell containing silicon dioxide" may become insufficient. The molar ratio (MO _x /SiO ₂ ) is more preferably 0.1 or less.

In this process, as in the second process, electrolyte salt can also be added. The addition amount is the same as in the second process, and the above-mentioned ratio (M _E /M _S ) is preferably 0.1-10. In addition, the full amount of electrolyte salt can also be added at the beginning of the third process. Alternatively, the electrolyte salt may be added continuously or intermittently while removing at least a part of elements other than silicon. However, in the third process, as long as the electrolyte salt added in the second process is not removed, the ratio based on the total amount of electrolyte salt added in the second process to the total amount of electrolyte salt added in the third process (M _E /M _S ) The electrolyte salt is added so as to be within the above-mentioned range. The ratio (M _E /M _S ) is more preferably 0.2-8.

[The fourth process]

In the fourth process, the dispersion liquid of silica-based particles is cleaned as needed. Thereafter, the dispersion of silica particles is heated to 200-800°C at a temperature increase rate of 0.3-3.0°C/min., and then the temperature is lowered at a rate of 0.04-2.0°C/min. so that the dispersion becomes at least less than 100°C. ℃.

If necessary, the dispersion liquid of silica-based particles after removing at least a part of elements other than silicon can be cleaned by a well-known cleaning method such as ultrafiltration. At least a part of the elements other than silicon dissolved by washing is removed. In this case, after removing a part of alkali metal ions and the like in the dispersion in advance, ultrafiltration is performed, thereby obtaining a dispersion of silica-based particles with high dispersion stability.

In addition, it is also possible to remove a part of dissolved elements other than silicon or alkali metal ions by contacting at least one of a cation exchange resin and an anion exchange resin with the dispersion after removing the elements. In addition, by heating and washing, the dispersion liquid of silica-based particles can be washed efficiently.

By washing the silica-based particle dispersion in this way, it is possible to effectively reduce the alkali metal impurities in the "particles with cavities inside the shell containing silica" obtained by heating the silica-based particles. And other content. Their content is based on the above-mentioned impurity content of "particles with cavities inside the shell containing silicon dioxide". For example, when represented by oxides, the elements that are alkali metals in the silicon dioxide-based particles after cleaning are 500 ppm or less _{with respect to SiO 2 respectively.}

If the respective contents of impurities in the silicon dioxide-based particles before cleaning are within the above-mentioned impurity range of the particles, there is no need to perform cleaning in this process.

In this way, the dispersion liquid of silica-based particles having a low content of alkali metals and the like is heated to 200 to 800°C at a temperature increase rate of 0.3 to 3.0°C/min. After heating, the temperature of the dispersion is lowered at a rate of 0.04 to 2.0°C/min. to at least less than 100°C.

In this embodiment, by heating the dispersion liquid of silica-based particles, a thermally free silicon component is precipitated on the silica-based particles. In addition, by cooling the dispersion liquid of silica-based particles, the thermally free silicon component is deposited and immobilized on the silica-based particles. By doing so, "particles with cavities inside the shell containing silicon dioxide" are produced.

Since such a shell containing silicon dioxide is dense, the inside remains in a gaseous or liquid phase with a low refractive index. Therefore, the particles themselves become dense and low refractive index particles.

Here, if the temperature increase rate is less than 0.3° C./min., it takes too much time for the temperature to be raised to the target temperature, resulting in poor production efficiency. If the temperature increase rate is faster than 3.0°C/min., the dissolution of the silicon component in the particles occurs rapidly. Therefore, it may not be possible to achieve densification of particles. The temperature increase rate is preferably 0.5 to 2.5°C/min., more preferably 0.8 to 2.2°C/min.

Next, if the heating temperature is less than 200°C, the precipitation of the silicon component in the particles may become insufficient. Even if the temperature exceeds 800°C, it is difficult to further increase the precipitation in the particles, and the manufacturing cost may increase. After heating the dispersion liquid of silica-based particles to a target temperature, the dispersion liquid of silica-based particles may be cooled. However, in order to stably produce "particles having a cavity inside the shell containing silica", it is preferable to maintain the temperature of the heated silica-based particle dispersion for 30 minutes or more. The heating temperature is preferably 360 to 750°C, more preferably 400 to 750°C.

Next, if the temperature drop rate is less than 0.04°C/min, the manufacturing cost may increase. If the cooling rate is faster than 2.0°C/min., although the deposition of silicon components on the silicon dioxide-based particles progresses, it may not be possible to achieve the densification of the particles. The cooling rate is preferably 0.08 to 1.8°C/min., more preferably 0.12 to 1.5°C/min.

As long as the temperature for cooling is less than 100°C. In order to facilitate the handling, the temperature of the dispersion liquid of silica-based particles may be lowered to normal temperature. However, as described later, when the silica particle dispersion is heated up again, if the temperature is lowered too much during the temperature drop, the temperature drop and the temperature rise may take a lot of time, or additional time may be required. energy. When the temperature of the temperature drop is lower than 100°C, it is not limited to the range of the temperature drop rate described above. For example, the temperature drop rate may be increased to perform the temperature drop.

In the fourth process, it is preferable to repeat the above-mentioned heating and cooling operations (treatments) multiple times. By repeating this operation, the dissolution and deposition of the silicon component are also repeated. Therefore, it is possible to obtain denser and lower refractive index "particles with cavities inside the shell containing silicon dioxide". The conditions when the operation is repeated may be the same every time, and the temperature increase rate or temperature may be changed.

The coating material for forming a film obtained by using the "particles having a cavity inside the shell containing silica" obtained in this way has improved stability, coating properties, and the like. In addition, when such particles are used in a film or the like, for example, substances with a high refractive index such as a matrix forming component are unlikely to enter the inside of the particle shell. Therefore, a transparent film having a low refractive index can be obtained. In addition, the film has excellent adhesion to the substrate, and has high hardness and strength.

In this embodiment, after the third process, that is, between the third process and the fourth process, a silica source with a low content of impurities is preferably added to the dispersion of silica-based particles. The source of silicon dioxide is, for example, silica sol, silicic acid liquid, or organic silicon compound. By adding the silicon dioxide source before the hydrothermal treatment of the fourth process, it is possible to obtain a more dense shell containing silicon dioxide, a low refractive index, and high hardness and strength. Particles with holes on the inside".

In order to more actively perform the dissolution and deposition of the silicon component in the fourth process, the addition of the silicon dioxide source is implemented. Therefore, the added silica source is preferably fine. For example, in the case of using a silica sol as the silica source, the average particle size is based on the average particle size of the silica-based particles, but is preferably approximately less than 30 nm. In addition, when the silicon dioxide source used is an organosilicon compound, the organosilicon compound represented by formula (2) in the first process described above can be used. When an organosilicon compound in which n is 0 in the formula (2) is used, it is preferable to use a partial hydrolysate of the organosilicon compound. The silicon dioxide source can be used alone or in combination.

Thus, in this embodiment, it is preferable that between the third process and the fourth process include adding at least one of the organosilicon compound represented by formula (2) and its partial hydrolysate to the dispersion of silica-based particles. Process.

_{The silicon dioxide source is preferably 1 to 200 parts by mass as SiO 2} relative to 100 parts by mass of the silicon dioxide-based particles, and is present as a solid content. Here, if the amount of the silicon dioxide source is less than 1 part by mass, the effect of the addition cannot be sufficiently obtained. Even if the amount of the silicon dioxide source is more than 200 parts by mass, the densification of the particles will not be further improved. Furthermore, since the refractive index of the particles increases, there is a possibility that particles having a desired refractive index cannot be obtained. The amount of the silicon dioxide source is more preferably 5 to 100 parts by mass, and still more preferably 20 to 55 parts by mass.

In the case of adding these silicon dioxide sources, it is also preferable to repeat the operations of raising the temperature and lowering the temperature a plurality of times as described above. From the viewpoint of the formation of the coating layer and the densification of the particles, it is preferable to perform the addition of the silicon dioxide source before the temperature rise.

The timing and frequency of addition of these silicon dioxide sources may be performed only once before the temperature rise, or may be performed every time the operation of raising the temperature and lowering the temperature is repeated. Alternatively, the addition of these silicon dioxide sources may be performed intermittently.

In this embodiment, it is preferable to perform surface treatment on the particles by adding an organosilicon compound after the fourth process.

As the added organosilicon compound, it is preferable to use an organosilicon compound represented by formula (2) in the first process described above and having n being 1 to 3. Here, in the case of using an organosilicon compound in which n is 0, it is preferable to use a partial hydrolyzate of the organosilicon compound.

In the surface treatment of the particles, an alcohol dispersion of the particles is prepared, and a predetermined amount of the organosilicon compound represented by the formula (2) and water are added to the dispersion. In this way, by hydrolyzing the organosilicon compound, the surface treatment of the particles is performed. In this hydrolysis, an acid or a base is used as a catalyst for hydrolysis as necessary.

_{It is preferable that the organosilicon compound is 0.1 to 100 parts by mass as R n} -SiO _{( 4-n ) /2} relative to 100 parts by mass of the particles, and exists as a solid content. If the particles are surface-treated with an organosilicon compound, the compatibility of the particles and the matrix forming components can be improved.

Here, if the amount of the organosilicon compound is less than 0.1 parts by mass, the effect of its addition cannot be sufficiently obtained. On the contrary, the dispersibility of the particles may become insufficient, and the resulting transparent film may have haze defects. Even if the amount of the organosilicon compound is more than 100 parts by mass, the dispersibility of the particles cannot be further improved. In addition, since the number of sites for bonding with the substrate increases, the adhesion between the particles and the substrate may become insufficient. The amount of the organosilicon compound is more preferably approximately 2 to 80 parts by mass, and still more preferably 3 to 50 parts by mass.

[Coating liquid for forming transparent film]

The above-mentioned particles can be used in a coating liquid for forming a transparent film. That is, the coating liquid contains particles, a matrix forming component, and an organic solvent. In addition to these, the coating liquid may also contain additives such as a polymerization initiator, a leveling agent, and a surfactant. Next, the main components contained in the coating liquid will be described.

The concentration of particles in the coating liquid is preferably 5 to 95% by mass relative to the total amount of solid components such as particles and matrix forming components contained in the coating liquid. If the concentration of the particles is less than 5% by mass, there is a possibility that the refractive index of the coating cannot be sufficiently reduced. Conversely, if the particle concentration is more than 95% by mass, cracks may occur in the film; the adhesion between the film and the substrate may become insufficient; and hardness, strength, transparency, and haze may deteriorate. The concentration of the particles is more preferably 10 to 85% by mass, and still more preferably 20 to 70% by mass.

As the matrix-forming component, an organic resin-based matrix-forming component is suitable. Examples of the matrix forming component include ultraviolet curable resins, thermosetting resins, and thermoplastic resins.

As ultraviolet curable resins, there are (meth)acrylic acid resins, γ-aminoacetoxy resins, urethane resins, vinyl resins, and the like. As thermosetting resins, there are urethane resins, melamine resins, silicone resins, butyral resins, reactive silicone resins, phenol resins, epoxy resins, unsaturated polyester resins, and thermosetting acrylic resins. . As the thermoplastic resin, there are polyester resins, polycarbonate resins, polyamide resins, polyphenylene ether resins, thermoplastic acrylic resins, chlorinated vinyl resins, fluororesins, vinyl acetate resins, and silicone rubbers. These resins may be two or more types of copolymers or modified products, or they may be used in combination. In addition, these resins may be emulsion resins, water-soluble resins, or hydrophilic resins.

Depending on the dispersibility of the particles and the ease of coating, the components forming these resins are preferably monomers or oligomers.

The concentration of the matrix-forming component in the coating liquid is preferably 5 to 95% by mass relative to the total amount of solid components such as particles and matrix-forming components contained in the coating liquid. When the concentration of the matrix forming component is less than 5% by mass, it is difficult to form a film. In addition, even if the film is obtained, cracks may occur in the film; the adhesion between the film and the substrate may become insufficient; and the hardness, strength, transparency, and haze may deteriorate. Conversely, if the concentration of the matrix forming component is more than 95% by mass, the amount of particles may be small, so there is a possibility that the refractive index cannot be sufficiently reduced. The concentration of the matrix forming component is more preferably 15 to 90% by mass, and still more preferably 30 to 80% by mass.

As the organic solvent, a solvent capable of uniformly dispersing particles and capable of dissolving or dispersing additives such as a matrix forming component and a polymerization initiator is used. Among them, hydrophilic solvents and polar solvents are preferred. Examples of hydrophilic solvents include alcohols, esters, glycols, and ethers. Examples of polar solvents include esters and ketones.

Examples of alcohols include methanol, ethanol, propanol, 2-propanol, butanol, diacetone alcohol, furfuryl alcohol, and tetrahydrofurfuryl alcohol.

Examples of esters include methyl acetate, ethyl acetate, isopropyl acetate, propyl acetate, isobutyl acetate, butyl acetate, isoamyl acetate, amyl acetate, and 3-methoxybutyl acetate. Ester, 2-ethylbutyl acetate, cyclohexyl acetate and ethylene glycol monoacetate, etc.

As the glycols, there are ethylene glycol, hexanediol, and the like.

Examples of ethers include diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol isopropyl ether, diethylene glycol monomethyl ether, and diethylene glycol monomethyl ether. Ethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether and propylene glycol monomethyl ether acetate, etc.

Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, butyl methyl ketone, cyclohexanone, methyl cyclohexanone, dipropyl ketone, methyl amyl ketone, and diisobutyl ketone. Ketones and so on.

As the polar solvent, there are dimethyl carbonate, toluene, and the like.

These can be used individually or in mixture of 2 or more types.

As the additive, any additive that can be used to form an anti-reflection film in the past can be used arbitrarily. For example, in order to promote the polymerization of the matrix-forming components and improve the film-forming properties, a polymerization initiator or a leveling agent is used.

As the polymerization initiator, for example, bis(2,4,6-trimethylbenzyl)phenyl phosphine oxide, bis(2,6-dimethoxybenzyl)-2,4, 4-trimethylpentyl phosphine oxide, 2-hydroxymethyl-2-methylphenylpropane-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one , 1-hydroxycyclohexyl phenyl ketone and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, etc.

Examples of the leveling agent include acrylic leveling agents, silicone leveling agents, and acrylic silicone leveling agents. As these leveling agents, it is preferable to use a leveling agent having a fluorine group.

The concentration of these additives in the coating liquid is included as a solid component when the film is formed. For convenience, it is included as a matrix forming component, and after the film is formed, it is included as a matrix.

The solid content concentration of the coating liquid (the ratio of the solid content of the total solid content of the particles and the solid content of the matrix forming component to the coating liquid) is preferably 0.1 to 60% by mass. If the solid content concentration of the coating liquid is less than 0.1% by mass, since the concentration stability of the coating material is low, it becomes difficult to apply the coating material. Therefore, it may be difficult to obtain a uniform film. In addition, due to the deterioration of haze or appearance, productivity and manufacturing reliability may be reduced. Conversely, if the solid content concentration of the coating liquid is higher than 60% by mass, the stability of the coating liquid may deteriorate. In addition, since the viscosity of the coating liquid becomes higher, the coatability may be reduced. In addition, the haze of the film may increase, the surface roughness may increase, and the strength may become insufficient. The solid content concentration of the coating liquid is more preferably 1 to 50% by mass.

[Method for manufacturing transparent film-coated substrate]

The substrate with a transparent coating includes a substrate and a transparent coating formed on the substrate. In the manufacture of a substrate with a transparent film, the above-mentioned coating liquid is used to form a transparent film on the substrate.

Specifically, after the coating liquid is applied to the substrate, drying and ultraviolet irradiation are performed to form a transparent film on the substrate. The coating method of the coating liquid is not particularly limited as long as it is a method capable of forming a transparent film on the substrate. As a coating method of the coating liquid, a well-known method can be adopted. Examples of well-known methods include spray coating, spin coating, roll coating, bar coating, slit coating printing, gravure printing, and microgravure printing. In the drying, for example, by heating the base material to about 50 to 150°C, the solvent is evaporated and the solvent is removed. Thereafter, by irradiating the substrate with ultraviolet rays, the polymerization of the resin component is promoted, and the hardness of the coating film is achieved. The transparent film is mainly formed of a matrix (resin) component and particles.

In this way, a substrate with a transparent coating in which a transparent coating is formed on the substrate is produced. The transparent film contains particles and a matrix. In the transparent film, the ratio of the particles in the coating liquid to the solid content of the matrix forming component is the ratio of the particle components in the film to the matrix as it is. As described above, the additives remaining as solid components among the additives in the coating liquid are included here as the matrix.

The thickness of the transparent coating is preferably 80 to 350 nm. If the film thickness is thinner than 80 nm, the strength and scratch resistance of the film may become insufficient. In addition, since the film is too thin, sufficient anti-reflection performance cannot be obtained. Conversely, if the film thickness is thicker than 350 nm, since cracks are likely to occur in the film, the strength of the film may become insufficient. In addition, since the film is too thick, the performance of preventing reflection may decrease. In addition, in the case of very large shrinkage, there is also the possibility of cracks. The film thickness is more preferably 85 to 220 nm, and still more preferably 90 to 110 nm.

In addition, the refractive index of the transparent film is preferably 1.10 to 1.45.

It is difficult to obtain a transparent film with a refractive index of less than 1.10. In addition, if the refractive index exceeds 1.45, the refractive index of the base material or the refractive index of another film formed as a lower layer of a transparent film formed as needed may be different, but the performance of preventing reflection may become insufficient. .

The refractive index of the transparent film of this embodiment is measured with an ellipsometer (EMS-1 manufactured by ULVAC). The refractive index of the transparent film is more preferably 1.15 to 1.35.

The light transmittance of the substrate with a transparent coating film is preferably 85.0% or more. If the light transmittance is less than 85.0%, the sharpness of the image may become insufficient in a display device or the like. The light transmittance is more preferably 90.0% or more.

In addition, the haze of the substrate with a transparent coating film is preferably 3% or less, and more preferably 0.3% or less.

In addition, the reflectance of the substrate with a transparent coating film is preferably 2.0% or less, and more preferably 1.2% or less.

The strength (scratch resistance) of the transparent film was evaluated by sliding #0000 steel wool on the transparent film ^{with a load of 1 kg/cm 2.} It is preferable that no stripe-shaped scratches are seen on the film surface at the time when the number of sliding times becomes at least 100 times, it is more preferable that no scratches are seen when the number of sliding times becomes 500 times, and it is still more preferable that the number of sliding times becomes 1000 times. No scars were seen at the point in time.

The pencil hardness of the transparent film is preferably 2H or more. When the pencil hardness is less than 2H, the hardness is insufficient as an anti-reflection film. The pencil hardness is more preferably 3H or higher, and still more preferably 4H or higher.

As the substrate, a well-known substrate can be used. For example, polycarbonate, acrylic resin, polyethylene terephthalate (PET), cellulose triacetate (TAC), polymethyl methacrylate resin (PMMA), and cycloolefin polymer (COP) are preferably transparent的resin substrate. These substrates have excellent adhesion to the transparent film formed from the above-mentioned coating liquid. Therefore, by using these base materials, a base material with a transparent coating film excellent in hardness, strength, and the like can be obtained. Therefore, it is especially suitable for thin substrates. The thickness of the substrate is not particularly limited, but is preferably 10 to 100 μm, more preferably 20 to 80 μm.

In addition, a substrate with a film in which another film is formed on such a substrate can also be used. As another coating film, for example, conventionally well-known primer films, hard coat films, high refractive index films, and conductive films can be cited.

Hereinafter, examples of the present invention will be described. Here, the particles after surface treatment with an organosilicon compound are exemplified.

[Example 1]

<Production of particles (P1) with voids on the inside of a shell containing silicon dioxide>

Pure water was added to 50 g of seed particle aqueous dispersion (USBB-120 manufactured by Nikkei Catalyzer Kasei Co., Ltd., average particle size 25nm, solid content concentration 20% by mass, and Al ₂ O ₃ content in solid content 27% by mass) 9950g. Thereafter, by adding 1% by mass of sodium hydroxide to the dispersion liquid, the pH of the dispersion liquid was adjusted to 11.0. After that, the dispersion was heated to 98°C, and 1.87 kg of a sodium silicate aqueous solution with a concentration of 1.5% by mass _{as SiO 2 and} a sodium aluminate aqueous solution with a concentration of 0.5% by mass _{as Al 2} O _{3 were added to the dispersion.} 1.87kg. After that, the dispersion liquid was washed by the centrifugal sedimentation method. Thus, a dispersion liquid of composite oxide particles (a-1) was obtained. The average particle diameter of the composite oxide particles (a-1) was 44 nm.

The dispersion of the composite oxide particles (a-1) was heated to 98°C, and 6.31 kg of a sodium silicate aqueous solution with a concentration of 1.5% by mass as SiO2 and a concentration of 0.5 _{as Al 2} O _{3 were added to the dispersion.} The mass% sodium aluminate aqueous solution 2.10kg. After that, the dispersion liquid was washed with an ultrafiltration membrane so that the solid content concentration was 13% by mass. After that, the dispersion was filtered with a capsule filter with a pore diameter of 1 μm. Thus, a dispersion liquid of composite oxide particles (b-1) was obtained. The average particle diameter of the composite oxide particles (b-1) was 58 nm.

To 500 g of the dispersion liquid of the composite oxide particles (b-1), 1125 g of pure water was added. Furthermore, concentrated hydrochloric acid (concentration 35.5% by mass) was dropped on the dispersion liquid to make the pH of the dispersion liquid 1.0. While adding 10 L of a pH 3 hydrochloric acid aqueous solution and 5 L of pure water to this dispersion, the dissolved aluminum salt was separated using an ultrafiltration membrane, and the dispersion was washed. In this way, a dispersion liquid of silica-based particles (C-1) having a concentration of 5% by mass was obtained.

Next, 12.8g of silica sol (CATALOID SI-550 manufactured by Nikkei Catalyzer Kasei Co., Ltd., with an average particle size of 5nm) was added to 100 g of the dispersion of silica-based particles (C-1) as a silica source. The solid content concentration is 20% by mass, and the Na ₂ O concentration is 0.8% by mass), and the mixture is sufficiently stirred. Thereafter, by adding ammonia water, the pH of the dispersion liquid was adjusted to 10.8. The temperature of the dispersion was raised from 25°C to 360°C in 335 minutes and maintained for 24 hours. After that, the dispersion liquid was cooled to 25°C over 420 minutes. After that, the dispersion liquid was heated again from 25°C to 360°C in 335 minutes, and maintained for 24 hours. After that, the dispersion liquid was cooled to 25°C over 420 minutes. After that, the same operation was performed again (3 times in total). After that, 400 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was used to perform ion exchange for 3 hours. Next, 200 g of an anion exchange resin (DIAION SA20A manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for 3 hours. Thereafter, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was further used to perform ion exchange at 80° C. for 3 hours, thereby performing washing. In this way, an aqueous dispersion of particles (P1) having voids on the inside of the shell containing silica is obtained. The solid content concentration of this dispersion was 20% by mass.

Using an ultrafiltration membrane, the solvent of the aqueous dispersion of the particles (P1) was replaced with methanol. Thus, a methanol dispersion liquid of particles (P1) having a solid content concentration of 20% by mass was prepared.

Next, 6 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the methanol dispersion of the particles (P1), and the mixture was heated at 50°C for 6 hours. Heat treatment. After that, the solvent was replaced with methyl isobutyl ketone (MIBK) using an evaporator. Thus, a MIBK dispersion of particles (P1) having a solid content concentration of 20% by mass was obtained.

Table 1 shows the production conditions of the particles (P1). In addition, for the particles (P1), the properties measured by the following methods are shown in Table 2 (the same applies to the following examples and comparative examples).

The physical properties of the particles (P1) are measured by image analysis. Specifically, first, the MIBK dispersion of the particles (P1) was diluted to 0.01% by mass with methanol, and then dried on the collodion film of a copper cell for electron microscopy. Next, a field emission transmission electron microscope (HF5000 manufactured by Hitachi High-Technologies Co., Ltd.) was used to take a photograph of the above sample at a magnification of 1 million times. For arbitrary 1000 particles in the obtained photographic projection image (SEM image, TEM photograph), the measurement is performed by the following methods (1) to (5).

(1) Average particle size (D)

According to the image processing of the SEM image, the area of the particle (P1) is obtained. From this area, find the equivalent circle diameter. The average value of the equivalent circle diameter is regarded as the average particle diameter of the particles.

(2) Hole diameter

From the TEM photograph, the area of the cavity inside the outer shell of the particle (P1) was obtained. Based on this area, the equivalent circle diameter is obtained, and the equivalent circle diameter is defined as the cavity diameter. In addition, the average value of the diameter of the cavity is taken as D _O.

(3) Particle shape

The ratio of the short axis to the long axis of the particle (P1) is obtained from the SEM image. Here, if the average value of the ratio (longer diameter/shorter diameter) is less than 1.2, it is determined that the particle shape is spherical.

(4) The shape of the cavity and the proportion of particles with one cavity

From the TEM photograph, the ratio of the short axis to the long axis of the cavity inside the shell of the particle (P1) was determined. Here, if the average value of the ratio (longer diameter/shorter diameter) is less than 1.2, it is determined that the particle shape is spherical. In addition, the number of voids in the particles is measured, and the ratio is calculated.

(5) Pore volume _{by N 2 adsorption method}

The MIBK dispersion of particles (P1) was dried at 105°C using an evaporator. 1 g of the powder was taken in a sample tube, and a nitrogen adsorption device (BELSORP-mini II (manufactured by MicrotracBEL)) was used to adsorb nitrogen gas to the powder, and the pore volume was measured.

(6) Refractive index of particles (n _a )

The MIBK dispersion liquid of the particles (P1) is collected in an evaporator to evaporate the dispersion medium. Next, the evaporated product was dried at 120°C to make it into a powder. Drop two or three drops of a standard refracting liquid with a known refractive index on the glass plate, and mix the above-mentioned powder with it. Various standard refracting fluids are used for this operation. The refractive index of the standard refracting liquid when the mixed liquid becomes transparent is defined as the refractive index of the silica-based hollow particles.

(7) The shell refractive index of the particle (n _s )

Using the average particle diameter (D) of the particles, the average value of the cavity diameter inside the shell (D _O ), and the refractive index (n _a ) of the particles obtained by the aforementioned method, the shell refractive index of the particles ( n _s ).

[Math 2]

D is the average particle size, D ₀ is the average diameter of the voids inside the housing, n _a is the refractive index particles, n _p is the refractive index of the cavity.

(8) Carbon content

The MIBK dispersion liquid of the particles (P1) was dried at 120°C and fired at 400°C. The burned material was measured using a carbon-sulfur analyzer (EMIA-320V manufactured by HORIBA), and the carbon content in the particles (P1) was obtained.

(9) _{Q 1} , Q ₂ , Q ₃ , Q ₄ and their ratios ^{using 29} Si-NMR

Put the MIBK dispersion of particles (P1) into a dedicated glass cell. To this dispersion, 5 mass% of tetramethylsilane as a reference substance was added. Furthermore, the dispersion liquid was measured using an NMR device (JNM-EX270 model manufactured by JEOL Co., Ltd., analysis software Excalibur manufactured by JEOL Co., Ltd.). More specifically, the single pulse non-decoupling _{method is used to determine the peak area (Q 1} ) that appears in the chemical shift of -78 to -88 ppm and the chemical shift ^{of the 29 Si-NMR spectrum method.} -88～-98ppm peak area (Q ₂ ), chemical shift -98～-108ppm peak area (Q ₃ ) and chemical shift -108～-117ppm peak area (Q ₄ ) , The ratio (Q ₁ /ΣQ), the ratio (Q ₂ /ΣQ), and the ratio (Q ₃ /Q ₄ ) are calculated.

(10) Content of alkali metals and other elements

Measure the content of alkali metals in the particles (P1) as follows, the content of Fe, Ti, Zn, Pd, Ag, Mn, Co, Mo, Sn, Al and Zr, the content of Cu, Ni and Cr, and the content of U and Th Content. First, the particles are dissolved in hydrofluoric acid, and after heating to remove the hydrofluoric acid, pure water is added as necessary to obtain a solution. The obtained solution is measured using an ICP inductively coupled plasma atomic emission spectrometry analyzer (for example, ICPM-8500 manufactured by Shimadzu Corporation) to measure the aforementioned content.

(11) Silicon dioxide content

The MIBK dispersion of particles (P1) was dried at 120°C for 12 hours. The dried product was measured using a fluorescent X-ray analyzer (EA600VX manufactured by Hitachi High-Tech Science Co., Ltd.) to determine the content _{of silicon dioxide (SiO 2 ).}

<Production of coating liquid (1) for forming transparent anti-reflection coating>

The MIBK dispersion liquid of the particles (P1) was diluted so that the solid content concentration became 5% by mass. By thoroughly mixing 50 g of this diluted dispersion, 1.67 g of acrylic resin (HITALOID 1007 manufactured by Hitachi Chemical Co., Ltd.), and 52.6 g of a 1/1 (mass ratio) mixed solvent of isopropanol and n-butanol, a transparent film was prepared. Use the coating solution (1). The coating liquid for forming a transparent film is shown in Table 3 (the same applies to the following Examples and Comparative Examples).

<Production of base material (1) with transparent anti-reflection coating>

The hard coat paint (ELCOM HP-1004 manufactured by Nikkei Kasei Kasei Co., Ltd.) was applied to the TAC film (FT-PB80UL-M manufactured by PANAC Co., Ltd., thickness 80μm, refractive index 1.51) by bar coating method (#18) ), dry at 80°C for 120 seconds. Thereafter, by irradiating ^{ultraviolet rays of 300 mJ/cm 2} to cure the hard coat film paint, a hard coat film was produced. The film thickness of the hard coat film was 8 μm.

Next, the coating solution (1) for forming a transparent anti-reflection film was coated on the TAC film on which the hard coat film was formed by a bar coating method (#4), and dried at 80° C. for 120 seconds. ^{Thereafter, 600 mJ/cm 2} of ultraviolet rays were irradiated in a N2 atmosphere to cure the coating liquid (1), thereby manufacturing a base material (1) with a transparent antireflection coating film.

For the following items, the base material (1) with a transparent anti-reflection coating was measured. The measurement results are shown in Table 3 (the same applies to the following Examples and Comparative Examples).

(12) Film thickness, refractive index, reflectivity

Using an ellipsometer (manufactured by ULVAC, EMS-1), the base material (1) with a transparent anti-reflection coating film, the film thickness, the film refractive index, and the reflectance of light with a wavelength of 550 nm were measured.

(13) Total light transmittance and haze

Using a haze meter (manufactured by Suga Tester Co., Ltd.), the total light transmittance and haze of the base material (1) with a transparent anti-reflection coating film were measured.

(14) Adhesion

A knife was used to form 11 parallel flaws on the surface of the base material (1) with a transparent anti-reflection coating at an interval of 1 mm in the vertical and horizontal directions to produce 100 squares. Attach cellophane tape to the square-shaped surface. Next, when the cellophane tape was peeled off, the number of squares in which the film was not peeled off and remained was classified into the following three levels to evaluate the adhesiveness.

The number of remaining squares is more than 90: ◎

The number of remaining squares is 85～89: ○

The number of remaining squares is less than 84: △

(15) Determination of scratch resistance

Slide #0000 steel wool on the surface of the film 100 times with a load of 1500 g/cm ^2. The surface of the film was visually observed, and the scratch resistance was evaluated according to the following criteria.

Evaluation criteria:

No stripes of scars are seen: ◎

Only a few strips of scars are seen: ○

Saw a lot of striped scars: △

The whole surface is ground: ×

(16) Pencil hardness

According to JIS K 5400, the pencil hardness is measured with a pencil hardness tester. That is, the pencil was set on the surface of the transparent film so as to become an angle of 45 degrees. Apply a load to the pencil with a prescribed weight and pull the pencil at a certain speed to observe whether there are any scars on the surface of the transparent film.

[Example 2]

<Production of particles (P2) with voids inside a shell containing silicon dioxide>

To the water dispersion of seed particles (USBB-120 manufactured by Nikkei Catalyzer Kasei Co., Ltd., average particle size 25nm, solid content concentration 20% by mass, and solid content of Al ₂ O ₃ content 27% by mass) 750 g, 29250 g of pure water was added . After that, the pH of the dispersion was adjusted to 11.0 by adding 1% by mass of sodium hydroxide to the dispersion. After that, the dispersion was heated to 98°C, and 5.83 kg of sodium silicate aqueous solution with a concentration of 1.5% by mass _{as SiO 2} and sodium aluminate aqueous solution with a concentration of 0.5% by mass _{as Al 2} O _{3 were added to the dispersion.} 5.83kg. After that, the dispersion liquid was washed by the centrifugal sedimentation method. Thus, a dispersion liquid of composite oxide particles (a-2) was obtained. At this time, the average particle diameter of the composite oxide particles (a-2) was 225 nm.

The dispersion of the composite oxide particles (a-2) was heated to 98°C, and 2.21 kg of sodium silicate aqueous solution with a concentration of _{SiO 2 of 1.5% by mass and Al 2} O ₃ with a concentration of 0.5% by mass were added 0.74kg of sodium aluminate aqueous solution. After that, the dispersion liquid was washed with an ultrafiltration membrane so that the solid content concentration was 13% by mass. After that, the dispersion liquid was filtered with a capsule filter having a mesh size of 1 μm. Thus, a dispersion liquid of composite oxide particles (b-2) was obtained. The average particle diameter of the composite oxide particles (b-2) was 240 nm.

To 500 g of the dispersion liquid of the composite oxide particles (b-2), 1125 g of pure water was added. In addition, concentrated hydrochloric acid (concentration 35.5% by mass) was dropped on the dispersion liquid to make the pH of the dispersion liquid 1.0. While adding 10 L of a pH 3 hydrochloric acid aqueous solution and 5 L of pure water to the dispersion, the dissolved aluminum salt was separated using an ultrafiltration membrane, and the dispersion was washed. In this way, a dispersion liquid of silica-based particles (C-2) having a concentration of 5% by mass was obtained.

Next, 2.5 g of silica sol (CATALOID SI-50 manufactured by Nikkei Catalyzer Kasei Co., Ltd., with an average particle size of 25 nm, was added as a silica source to 100 g of the dispersion of silica particles (C-2). The solid content concentration is 48% by mass, and the Na ₂ O concentration is 0.5% by mass), and the mixture is sufficiently stirred. Thereafter, by adding ammonia water, the pH of the dispersion liquid was adjusted to 10.5. The temperature of the dispersion was raised from 25°C to 360°C in 335 minutes and maintained for 24 hours. After that, the dispersion liquid was cooled to 25°C over 420 minutes. After that, the dispersion liquid was heated again from 25°C to 360°C in 335 minutes, and maintained for 24 hours. After that, the dispersion liquid was cooled to 25°C over 420 minutes. After that, the same operation was performed again (3 times in total). After that, 400 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was used to perform ion exchange for 3 hours. Next, 200 g of an anion exchange resin (DIAION SA20A manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for 3 hours. Thereafter, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was further used to perform ion exchange at 80° C. for 3 hours, thereby performing washing. In this way, an aqueous dispersion of particles (P2) having voids on the inside of the shell containing silica is obtained. The solid content concentration of this dispersion was 20% by mass.

Using an ultrafiltration membrane, the solvent of the aqueous dispersion of the particles (P2) was replaced with methanol. Thus, a methanol dispersion liquid of particles (P2) having a solid content concentration of 20% by mass was prepared.

Next, 2 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the methanol dispersion of the particles (P2), and the mixture was heated at 50°C for 6 hours. Heat treatment. After that, the solvent was replaced with MIBK using an evaporator. Thus, a MIBK dispersion of particles (P2) having a solid content concentration of 20% by mass was obtained.

<Manufacturing of coating liquid (2) for forming transparent anti-reflection film and base material (2) with the film>

Except that the MIBK dispersion of particles (P2) was used instead of the MIBK dispersion of particles (P1), the same method as in Example 1 was used to produce a coating solution for forming a transparent anti-reflection coating (2) and a belt anti-reflection Using the transparent film substrate (2), each characteristic was evaluated.

[Example 3]

<Production of particles (P3) with voids inside a shell containing silicon dioxide>

17000 g of pure water was added to 3000 g of an aqueous dispersion of seed particles (CATALOID SI-550 manufactured by Nikkei Catalyzer Kasei Co., Ltd., average particle size of 5 nm, and SiO _{2 concentration of 20% by mass).} Thereafter, by adding 1% by mass of sodium hydroxide to the dispersion liquid, the pH of the dispersion liquid was adjusted to 10.0. Thereafter, the dispersion was heated to 80°C, and 1369 g of sodium silicate aqueous solution with a concentration of 1.5% by mass _{as SiO 2} and 1369 g of sodium aluminate aqueous solution with a concentration of 0.5% by mass _{as Al 2} O _{3 were added to the dispersion.} . After that, the dispersion liquid was washed by the centrifugal sedimentation method. Thus, a dispersion liquid of composite oxide particles (a-3) was obtained. At this time, the average particle diameter of the composite oxide particles (a-3) was 19 nm.

The dispersion of the composite oxide particles (a-3) was heated to 85°C, and 2820 g of sodium silicate aqueous solution with a concentration of 1.5% by mass _{as SiO 2} and aluminum with a concentration of 0.5% by mass _{as Al 2} O _{3 were added.} Sodium aqueous solution 940g. After that, the dispersion liquid was washed with an ultrafiltration membrane so that the solid content concentration was 13% by mass. After that, the dispersion liquid was filtered with a capsule filter having a mesh size of 1 μm. Thus, a dispersion liquid of composite oxide particles (b-3) was obtained. The average particle diameter of the composite oxide particles (b-3) was 22 nm.

To 500 g of the dispersion liquid of the composite oxide particles (b-3), 1125 g of pure water was added. In addition, concentrated hydrochloric acid (concentration 35.5% by mass) was dropped on the dispersion liquid to make the pH of the dispersion liquid 1.0. While adding 10 L of a pH 3 hydrochloric acid aqueous solution and 5 L of pure water to the dispersion, the dissolved aluminum salt was separated using an ultrafiltration membrane, and the dispersion was washed. In this way, a dispersion liquid of silica-based particles (C-3) having a concentration of 5% by mass was obtained.

Next, 52.5 g of a silicic acid solution (4.0% by mass _{as SiO 2 and 12} ppm of Na 2 O) as a source of silica was added to 100 g of the dispersion of silica-based particles (C-3), and the mixture was sufficiently stirred. Thereafter, by adding ammonia water, the pH of the dispersion liquid was adjusted to 9.5. The temperature of the dispersion was raised from 25°C to 360°C in 335 minutes and maintained for 24 hours. After that, the dispersion liquid was cooled to 25°C over 420 minutes. After that, the dispersion liquid was heated again from 25°C to 360°C in 335 minutes, and maintained for 24 hours. After that, the dispersion liquid was cooled to 25°C over 420 minutes. After that, the same operation was performed again (3 times in total). After that, 400 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was used to perform ion exchange for 3 hours. Next, 200 g of an anion exchange resin (DIAION SA20A manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for 3 hours. Thereafter, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was further used to perform ion exchange at 80° C. for 3 hours, thereby performing washing. In this way, an aqueous dispersion of particles (P3) having voids on the inside of the shell containing silica was obtained. The solid content concentration of this dispersion was 20% by mass.

The solvent of the aqueous dispersion of the particles (P3) was replaced with methanol using an ultrafiltration membrane. Thus, a methanol dispersion liquid of particles (P3) having a solid content concentration of 20% by mass was prepared.

Next, 10 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the methanol dispersion of the particles (P3), and the mixture was heated at 50°C for 6 hours. Heat treatment. After that, the solvent was replaced with MIBK using an evaporator. Thus, a MIBK dispersion of particles (P3) having a solid content concentration of 20% by mass was obtained.

<Manufacturing of the coating liquid (3) for forming a transparent film for preventing reflection and the base material (3) with the film>

Use the MIBK dispersion of particles (P3) instead of the MIBK dispersion of particles (P1), using acrylic resin (HITALOID 1007 manufactured by Hitachi Chemical Co., Ltd.) 1.07 g and 1/1 (mass ratio) of isopropanol and n-butanol Except for the mixed solvent 85.7g, the same method as in Example 1 was used to produce a coating solution for forming a transparent antireflection film (3) and a base material with a transparent antireflection film (3), and each characteristic was evaluated. Evaluation.

[Example 4]

<Production of particles (P4) with voids on the inside of a shell containing silicon dioxide>

Add 128 g of silica sol (CATALOID SI-550 manufactured by Nikkei Catalyzer Kasei Co., Ltd.) to 1000 g of silica-based particles (C-1) dispersion liquid as a silica source, average particle size 5nm, solid content concentration 20% by mass, Na ₂ O concentration 0.8% by mass), and fully stirred. Next, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for this dispersion for 1 hour.

Next, by adding ammonia water, the pH of the dispersion liquid was adjusted to 10.0. The dispersion was dried at 110°C over 6 hours to obtain a powder. The temperature of the powder was increased from 25°C to 750°C in 258 minutes and maintained for 5 hours. Thereafter, the powder was cooled to 50°C in 375 minutes.

Then, after adding 500 g of water to 50 g of powder, a 1% NaOH aqueous solution was added so that the pH became 10.2. After that, a ZrO ₂ medium of 0.02 mm was used to perform dispersion treatment with a bead mill.

After that, 400 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was used to perform ion exchange for 3 hours. Next, 200 g of an anion exchange resin (DIAION SA20A manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for 3 hours. Thereafter, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was further used to perform ion exchange at 80° C. for 3 hours, thereby performing washing. In this way, an aqueous dispersion of particles (P4) having voids on the inside of the shell containing silica was obtained. The solid content concentration of this dispersion was 20% by mass.

The solvent of the aqueous dispersion of the particles (P4) was replaced with methanol using an ultrafiltration membrane. Thus, a methanol dispersion liquid of particles (P4) having a solid content concentration of 20% by mass was prepared.

Next, 6 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the methanol dispersion of the particles (P4), and the mixture was heated at 50°C for 6 hours. Heat treatment. After that, the solvent was replaced with MIBK using an evaporator. Thus, a MIBK dispersion liquid of particles (P4) having a solid content concentration of 20% by mass was obtained.

<Production of coating liquid (4) for forming transparent film for preventing reflection and base material (4) with the film>

The MIBK dispersion of the particles (P4) was used instead of the MIBK dispersion of the particles (P1). The same method as in Example 1 was used to produce a coating solution for forming a transparent anti-reflection coating (4) and a belt anti-reflection Using the transparent film substrate (4), each characteristic was evaluated.

[Example 5]

<Production of particles (P5) with voids on the inside of a shell containing silicon dioxide>

Add 62.5g of silica sol (CATALOID SI-550 manufactured by Nikkei Catalyzer Kasei Co., Ltd.) to 1000 g of silica-based particles (C-1) dispersion liquid as a silica source, average particle size 5nm, solid content The concentration is 20% by mass, and the Na ₂ O concentration is 0.8% by mass), and the mixture is sufficiently stirred.

Next, by adding ammonia water, the pH of the dispersion liquid was adjusted to 10.5. The temperature of the dispersion was raised from 25°C to 200°C in 583 minutes and maintained for 24 hours. Thereafter, the dispersion liquid was cooled to 25°C over 4400 minutes. Repeat this operation twice.

After that, 400 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was used to perform ion exchange for 3 hours. Next, 200 g of an anion exchange resin (DIAION SA20A manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for 3 hours. Thereafter, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was further used to perform ion exchange at 80° C. for 3 hours, thereby performing washing. In this way, an aqueous dispersion of particles (P5) having voids on the inside of the shell containing silica was obtained. The solid content concentration of this dispersion was 20% by mass.

The solvent of the aqueous dispersion of the particles (P5) was replaced with methanol using an ultrafiltration membrane. Thus, a methanol dispersion liquid of particles (P5) having a solid content concentration of 20% by mass was prepared.

Next, 6 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the methanol dispersion of the particles (P5), and the mixture was heated at 50°C for 6 hours. Heat treatment. After that, the solvent was replaced with MIBK using an evaporator. In this way, a MIBK dispersion of particles (P5) having a solid content concentration of 20% by mass was obtained.

<Manufacturing of coating liquid (5) for forming a transparent film for preventing reflection and base material (5) with the film>

The MIBK dispersion of the particles (P5) was used instead of the MIBK dispersion of the particles (P1). The same method as in Example 1 was used to produce a coating solution for forming a transparent anti-reflection coating (5) and a belt anti-reflection Using the transparent film substrate (5), each characteristic was evaluated.

[Example 6]

<Production of particles (P6) with voids on the inside of a shell containing silicon dioxide>

After adding 1000 g of ethanol and 50 g of ammonia to 1000 g of the dispersion liquid of silica-based particles (C-1), the liquid temperature was adjusted to 35°C. To this dispersion, 88.5 g of tetraethoxysilane as a source of silica was added, and the mixture was sufficiently stirred. After that, an ultrafiltration membrane was used to replace the solvent with water.

Next, by adding ammonia water, the pH of the dispersion liquid was adjusted to 10.5. The temperature of the dispersion was raised from 25°C to 360°C in 335 minutes and maintained for 24 hours. Thereafter, the dispersion liquid was cooled to 25°C in 419 minutes. Repeat this operation 3 times.

After that, 400 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was used to perform ion exchange for 3 hours. Next, 200 g of an anion exchange resin (DIAION SA20A manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for 3 hours. Thereafter, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was further used to perform ion exchange at 80° C. for 3 hours, thereby performing washing. In this way, an aqueous dispersion of particles (P6) having voids on the inside of the shell containing silica was obtained. The solid content concentration of this dispersion was 20% by mass.

The solvent of the aqueous dispersion of the particles (P6) was replaced with methanol using an ultrafiltration membrane. Thus, a methanol dispersion liquid of particles (P6) having a solid content concentration of 20% by mass was prepared.

Next, 6 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the methanol dispersion of the particles (P6), and the mixture was heated at 50°C for 6 hours. Heat treatment. After that, the solvent was replaced with MIBK using an evaporator. In this way, a MIBK dispersion of particles (P6) having a solid content concentration of 20% by mass was obtained.

<Production of coating liquid (6) for forming transparent film for preventing reflection and base material (6) with the film>

The MIBK dispersion of the particles (P6) was used instead of the MIBK dispersion of the particles (P1). The same method as in Example 1 was used to produce the coating solution for forming a transparent anti-reflection coating (6) and the belt anti-reflection Using the transparent film substrate (6), each characteristic was evaluated.

[Example 7]

<Production of particles (P7) with voids on the inside of a shell containing silicon dioxide>

Ammonia water was added to 1000 g of the dispersion of silica-based particles (C-1) to adjust the pH of the dispersion to 10.5. Thereafter, the dispersion was dried at 110°C over 6 hours, thereby obtaining a powder. The temperature of the powder was raised from 25°C to 360°C in 335 minutes and maintained for 24 hours. After that, the powder was cooled to 25°C over 420 minutes. Repeat this operation 3 times.

Then, after adding 500 g of water to 50 g of powder, a 1% NaOH aqueous solution was added so that the pH became 10.2. After that, using a ZrO ₂ medium of 0.02 mm, a bead mill was used to perform dispersion treatment.

After that, 400 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was used to perform ion exchange for 3 hours. Next, 200 g of an anion exchange resin (DIAION SA20A manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for 3 hours. Thereafter, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was further used to perform ion exchange at 80° C. for 3 hours, thereby performing washing. In this way, an aqueous dispersion of particles (P7) having voids inside the shell containing silica was obtained. The solid content concentration of this dispersion was 20% by mass.

The solvent of the aqueous dispersion of the particles (P7) was replaced with methanol using an ultrafiltration membrane. Thus, a methanol dispersion liquid of particles (P7) having a solid content concentration of 20% by mass was prepared.

Next, 6 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the methanol dispersion of the particles (P7), and the mixture was heated at 50°C for 6 hours. Heat treatment. After that, the solvent was replaced with MIBK using an evaporator. Thus, a MIBK dispersion of particles (P7) having a solid content concentration of 20% by mass was obtained.

<Production of coating liquid (7) for forming transparent film for preventing reflection and base material (7) with the film>

The MIBK dispersion of the particles (P7) was used instead of the MIBK dispersion of the particles (P1). The same method as in Example 1 was used to produce a coating solution for forming a transparent anti-reflection coating (7) and a belt anti-reflection Using the transparent film substrate (7), each characteristic was evaluated.

[Example 8]

<Production of particles (P8) with voids on the inside of a shell containing silicon dioxide>

To 1000 g of silica-based particles (C-1) dispersion, 128 g of high-purity silica sol (LNA-2000 manufactured by Nikkei Catalyzer Kasei Co., Ltd.) was added as a source of silica, with an average particle size of 23 nm and solid content. Concentration 12.6% by mass), and fully agitate.

Next, by adding ammonia water, the pH of the dispersion liquid was adjusted to 10.8. The dispersion was dried at 110°C over 6 hours, thereby obtaining a powder. The temperature of the powder was raised from 25°C to 360°C in 335 minutes and maintained for 24 hours. After that, the powder was cooled to 25°C over 420 minutes. Repeat this operation 3 times.

Then, after adding 500 g of water to 50 g of powder, a 1% NaOH aqueous solution was added so that the pH became 10.2. After that, using a ZrO ₂ medium of 0.02 mm, a bead mill was used to perform dispersion treatment.

After that, ion exchange was performed for 3 hours using 400 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Corporation). Next, 200 g of an anion exchange resin (DIAION SA20A manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for 3 hours. Thereafter, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was further used to perform ion exchange at 80° C. for 3 hours, thereby performing washing. In this way, an aqueous dispersion of particles (P8) having voids inside the shell containing silica was obtained. The solid content concentration of this dispersion was 20% by mass.

The solvent of the aqueous dispersion of the particles (P8) was replaced with methanol using an ultrafiltration membrane. Thus, a methanol dispersion liquid of particles (P8) having a solid content concentration of 20% by mass was prepared.

Next, 6 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the methanol dispersion of the particles (P8), and the mixture was heated at 50°C for 6 hours. Heat treatment. After that, the solvent was replaced with MIBK using an evaporator. In this way, a MIBK dispersion of particles (P8) having a solid content concentration of 20% by mass was obtained.

<Manufacturing of a coating liquid (8) for forming a transparent film for preventing reflection and a base material (8) with the film>

Using the MIBK dispersion of particles (P8) instead of the MIBK dispersion of particles (P1), the same method as in Example 1 was used to produce a coating solution for forming a transparent anti-reflection coating (8) and a tape anti-reflection Using the transparent film substrate (8), each characteristic was evaluated.

[Example 9]

<Production of particles (P9) with voids on the inside of a shell containing silicon dioxide>

Add 128 g of silica sol (CATALOID SI-550 manufactured by Nikkei Catalyzer Kasei Co., Ltd.) to 1000 g of silica-based particles (C-1) dispersion liquid as a silica source, average particle size 5nm, solid content concentration 20% by mass, Na ₂ O concentration 0.8% by mass), and fully stirred. Next, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for this dispersion for 1 hour.

Thereafter, by adding ammonia water, the pH of the dispersion liquid was adjusted to 10.8. Thereafter, the dispersion was dried at 110°C over 6 hours, thereby obtaining a powder. The temperature of the powder was raised from 25°C to 600°C in 575 minutes and maintained for 5 hours. After that, the powder was cooled to 50°C over 550 minutes. Repeat this operation 3 times.

Then, after adding 500 g of water to 50 g of powder, a 1% NaOH aqueous solution was added so that the pH became 10.0. After that, using a ZrO ₂ medium of 0.02 mm, a bead mill was used to perform dispersion treatment.

After that, 400 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was used to perform ion exchange for 3 hours. Next, 200 g of an anion exchange resin (DIAION SA20A manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for 3 hours. Thereafter, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was further used to perform ion exchange at 80° C. for 3 hours, thereby performing washing. In this way, an aqueous dispersion of particles (P9) having voids inside the shell containing silica was obtained. The solid content concentration of this dispersion was 20% by mass.

The solvent of the aqueous dispersion of the particles (P9) was replaced with methanol using an ultrafiltration membrane. Thus, a methanol dispersion liquid of particles (P9) having a solid content concentration of 20% by mass was prepared.

Next, 6 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the methanol dispersion of the particles (P9), and the mixture was heated at 50°C for 6 hours. Heat treatment. After that, the solvent was replaced with MIBK using an evaporator. In this way, a MIBK dispersion of particles (P9) having a solid content concentration of 20% by mass was obtained.

<Manufacturing of coating liquid (9) for forming transparent film for preventing reflection and base material (9) with the film>

The MIBK dispersion of the particles (P9) was used instead of the MIBK dispersion of the particles (P1). The same method as in Example 1 was used to produce a coating solution for forming a transparent anti-reflection coating (9) and a belt anti-reflection Using the transparent film substrate (9), each characteristic was evaluated.

[Comparative Example 1]

<Production of particles (R1) with voids on the inside of a shell containing silicon dioxide>

Add 62.5g of silica sol (CATALOID SI-550 manufactured by Nikkei Catalyzer Kasei Co., Ltd.) to 1000 g of silica-based particles (C-1) dispersion liquid as a silica source, average particle size 5nm, solid content The concentration is 20% by mass, and the Na ₂ O concentration is 0.8% by mass), and the mixture is sufficiently stirred.

Next, by adding ammonia water, the pH of the dispersion liquid was adjusted to 10.5. The dispersion liquid was heated from 25°C to 150°C in 25 minutes and kept for 24 hours. After that, the dispersion liquid was cooled to 25°C over 42 minutes.

After that, 400 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was used to perform ion exchange for 3 hours. Next, 200 g of an anion exchange resin (DIAION SA20A manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for 3 hours. Thereafter, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was further used to perform ion exchange at 80° C. for 3 hours, thereby performing washing. In this way, an aqueous dispersion of particles (R1) having voids on the inside of the shell containing silica is obtained. The solid content concentration of this dispersion was 20% by mass.

The solvent of the aqueous dispersion of the particles (R1) was replaced with methanol using an ultrafiltration membrane. Thus, a methanol dispersion liquid of particles (R1) having a solid content concentration of 20% by mass was prepared.

Next, 6 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the methanol dispersion of the particles (R1), and the mixture was heated at 50°C for 6 hours. Heat treatment. After that, the solvent was replaced with MIBK using an evaporator. Thus, a MIBK dispersion of particles (R1) having a solid content concentration of 20% by mass was obtained.

<Manufacturing of coating liquid (R1) for forming transparent film for preventing reflection and base material (R1) with the film>

The MIBK dispersion of the particles (R1) was used instead of the MIBK dispersion of the particles (P1). The same method as in Example 1 was used to produce the anti-reflection coating (R1) and the transparent anti-reflection coating. The base material (R1) of the film was evaluated for each characteristic.

[Comparative Example 2]

<Production of particles (R2) with voids on the inside of a shell containing silicon dioxide>

After adding 1000 g of ethanol and 50 g of ammonia to 1000 g of the dispersion liquid of silica-based particles (C-1), the liquid temperature was adjusted to 35°C. 57.9 g of methyltrimethoxysilane, which is a source of silicon dioxide, was added to this liquid, and the mixture was sufficiently stirred. After that, an ultrafiltration membrane was used to replace the solvent with water.

Next, by adding ammonia water, the pH of the dispersion liquid was adjusted to 10.5. Thereafter, the dispersion was heated from 25°C to 360°C in 335 minutes, and maintained for 24 hours. After that, the dispersion was cooled to 25°C in 419 minutes. Repeat this operation 3 times.

After that, 400 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was used to perform ion exchange for 3 hours. Next, 200 g of an anion exchange resin (DIAION SA20A manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for 3 hours. Thereafter, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was further used to perform ion exchange at 80° C. for 3 hours, thereby performing washing. In this way, an aqueous dispersion of particles (R2) having voids on the inside of the shell containing silica is obtained. The solid content concentration of this dispersion was 20% by mass.

The solvent of the aqueous dispersion of the particles (R2) was replaced with methanol using an ultrafiltration membrane. Thus, a methanol dispersion liquid of particles (R2) having a solid content concentration of 20% by mass was prepared.

Next, 6 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the methanol dispersion of the particles (R2), and the mixture was heated at 50°C for 6 hours. Heat treatment. After that, the solvent was replaced with MIBK using an evaporator. In this way, a MIBK dispersion of particles (R2) having a solid content concentration of 20% by mass was obtained.

<Production of coating liquid (R2) for forming a transparent film for preventing reflection and base material (R2) with the film>

Using the MIBK dispersion of the particles (R2) instead of the MIBK dispersion of the particles (P1), the same method as in Example 1 was used to produce the coating solution (R2) for forming a transparent anti-reflection coating and the belt anti-reflection Using the transparent film substrate (R2), each characteristic was evaluated.

[Comparative Example 3]

<Production of particles (R3) with voids on the inside of a shell containing silicon dioxide>

Add 62.5g of silica particles (CATALOID SI-550 manufactured by Nikkei Catalyzer Kasei Co., Ltd.) to 1000 g of silica-based particles (C-1) dispersion liquid as a source of silica, with an average particle size of 5nm and solid content The concentration is 20% by mass, and the Na ₂ O concentration is 0.8% by mass), and the mixture is sufficiently stirred.

Next, by adding 10.6 g of a 10% NaOH aqueous solution, the pH of the dispersion was adjusted to 10.5. Thereafter, the dispersion was heated from 25°C to 360°C in 335 minutes, and maintained for 24 hours. After that, the dispersion was cooled to 25°C in 419 minutes. Repeat this operation 3 times.

After that, 400 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was used to perform ion exchange for 3 hours. Next, 200 g of an anion exchange resin (DIAION SA20A manufactured by Mitsubishi Chemical Corporation) was used to perform ion exchange for 3 hours. Thereafter, 200 g of a cation exchange resin (DIAION SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was further used to perform ion exchange at 80° C. for 3 hours, thereby performing washing. In this way, an aqueous dispersion of particles (R2) having voids on the inside of the shell containing silica is obtained. However, the particle has a shape in which the shell has holes and the cavity inside the shell is not closed by the shell. The solid content concentration of this dispersion was 20% by mass.

The solvent of the aqueous dispersion of the particles (R3) was replaced with methanol using an ultrafiltration membrane. Thus, a methanol dispersion liquid of particles (R3) having a solid content concentration of 20% by mass was prepared.

Next, 6 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the methanol dispersion of the particles (R3), and the mixture was heated at 50°C for 6 hours. Heat treatment. After that, the solvent was replaced with MIBK using an evaporator. Thus, a MIBK dispersion of particles (R3) having a solid content concentration of 20% by mass was obtained.

<Production of coating liquid (R3) for forming a transparent film for preventing reflection and base material (R3) with the film>

Using the MIBK dispersion of the particles (R3) instead of the MIBK dispersion of the particles (P1), the same method as in Example 1 was used to produce the coating solution (R3) for forming a transparent anti-reflection coating and the belt anti-reflection Using the transparent film substrate (R3), each characteristic was evaluated.

[Table 1]

[Table 2]

[table 3]

no.

Fig. 1 is a cross-sectional view of a particle according to an embodiment of the present invention.

Claims (9)

A particle having a cavity inside a shell containing silica, wherein the average particle size D of the particle is 20 to 250 nm, and the diameter of the cavity is 0.5 to 0.5 of the diameter of the particle. 0.9 times the pore volume of the particles using N ₂ adsorption method is less than 1.0cm ³ / g, n _a refractive index of the particles is from 1.08 to 1.34, carbon content of the particles is 3.0 mass% or less, by the following _{The refractive index n S} of the shell calculated by the formula is 1.38 or more, [Math 1]

D is the average particle size, D ₀ is the average diameter of the voids inside the housing, n _a is the refractive index of particles, n _p is the refractive index of the cavity. The particle according to claim 1, wherein _{the area Q 1} of the peak appearing at a chemical shift of -78 to -88 ppm and the peak appearing at a chemical shift of -88 to -98 ppm ^{by 29 Si-NMR spectroscopy of the particle} The area Q _{2 , the area Q 3} of the peak appearing at the chemical shift -98～-108ppm _{, the area Q 4} of the peak appearing at the chemical shift -108～-117ppm, the ratio Q ₁ /(Q ₁ +Q ₂ ＋Q ₃ ＋Q ₄ ) Is substantially 0, the ratio Q ₂ /(Q ₁ +Q ₂ +Q ₃ +Q ₄ ) is substantially 0, and the ratio Q ₃ /Q ₄ is 0.01 to 0.7. The particle according to claim 1, wherein the respective content of the element belonging to the alkali metal of the particle, when the element is represented by an oxide, is 1 ppm or less _{with respect to SiO 2.} The particle according to claim 1, wherein the respective content of Fe, Ti, Zn, Pd, Ag, Mn, Co, Mo, Sn, Al, and Zr in the particle is less than 0.1 ppm, and each of Cu, Ni and Cr The content is less than 1 ppb, and the respective content of U and Th is less than 0.3 ppb. A coating liquid for forming a transparent film, characterized by containing the particles described in claim 1, a matrix-forming component, and an organic solvent. A substrate with a transparent coating, which is characterized by comprising: a substrate; and a transparent coating formed on the substrate, and comprising the particles according to claim 1 and a matrix. A method for manufacturing particles with voids inside a shell containing silicon dioxide, which includes: a first process, when the oxide of silicon is expressed as SiO ₂ , and the oxide of inorganic elements other than alkali-soluble silicon When expressed as MO _x , a solution of a compound containing silicon and an aqueous solution of a compound of the inorganic element are simultaneously added to the alkaline aqueous solution so that the molar ratio MO _x /SiO _{2 becomes 0.01 to 2, thereby preparing a composite oxidation} A dispersion liquid of the particles a; the second process, followed by the first process, to disperse the composite oxide particles a in such a way _{that the molar ratio MO x} /SiO _{2 is smaller than the molar ratio of the first process} A solution of a compound containing silicon and an aqueous solution of a compound of an inorganic element other than alkali-soluble silicon are added to the liquid, thereby preparing a dispersion liquid of composite oxide particles b; the third process, followed by the second process, An acid is added to the dispersion of the composite oxide particles b to remove at least a part of the elements other than silicon constituting the composite oxide particles b to prepare a dispersion of silica-based particles; and the fourth process is performed at a heating rate of 0.3 ～3.0℃/min. After heating the dispersion of silica particles to 200～800℃, the temperature is lowered at a rate of 0.04～2.0℃/min. to make the dispersion of silica particles The temperature is less than 100°C. The method for producing particles according to claim 7, wherein the fourth process includes repeating the heating and cooling treatments of the dispersion liquid of the silica-based particles multiple times. The method for producing particles according to claim 7, wherein, between the third process and the fourth process, the addition of the silica-based particles to the dispersion liquid is represented by the following formula (2) The preparation process of at least one of the organosilicon compound and its partial hydrolysate, R _n -SiX _4-n (2) In the formula, R is an unsubstituted or substituted hydrocarbon group with 1 to 10 carbons, which may be the same or different. , As substituents, there are epoxy groups, alkoxy groups, (meth)acryloxy groups, mercapto groups, halogen atoms, amino groups, and phenylamino groups, and X is an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, A halogen atom or a hydrogen atom, and n is an integer of 0-3.

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