KR20240101538A - A dispersion of particles having an outer shell containing functional groups and silicon and an inner cavity, and a method for producing this dispersion - Google Patents

Abstract

A dispersion of particles having a high dispersibility in a dispersion medium or resin is provided, in which an organosilicon compound is precisely supported on the surface of the particle having an outer shell containing silicon and a cavity inside the particle. These particles contain functional groups and silicon. The average primary particle diameter obtained by image analysis of these particles is 20 to 250 nm, and the carbon content of these particles is 0.5 to 10 mass%. The amount of the organosilicon compound contained in the liquid excluding the particles from the dispersion liquid containing these particles is 0.50 parts by mass or less as a solid content with respect to 100 parts by mass of the particles. According to this dispersion, a coating solution that has a low reflectance, excellent adhesion to the substrate, and can produce a film with high hardness and strength is obtained.

Description

A dispersion of particles having an outer shell containing functional groups and silicon and an inner cavity, and a method for producing this dispersion

The present disclosure relates to a dispersion of particles having an outer shell containing functional groups and silicon and an inner cavity, and a method for producing this dispersion.

Conventionally, in order to prevent reflection on the surface of a substrate such as glass, plastic sheet, or plastic lens, an antireflection film is formed on the surface. For example, a film of a low refractive index material such as fluororesin or magnesium fluoride is formed on the surface of a glass or plastic substrate by a coating method, a vapor deposition method, or a CVD method. However, these methods are expensive in terms of cost. Therefore, the following method is known (for example, Japanese Patent Application Laid-Open No. 7-133105). In this method, an antireflection film is formed by applying a coating liquid containing low refractive index particles containing silica or the like to the surface of a substrate.

Additionally, a method for producing particles having an outer shell containing silicon and a cavity inside the shell is known (see, for example, Japanese Patent Application Laid-Open No. 2001-233611 and Japanese Patent Application Laid-Open No. 2013-226539). These particles have a low refractive index. A transparent film formed using this has a low refractive index and excellent anti-reflection performance.

Additionally, in order to improve the pencil hardness (hardness) and scratch resistance (strength) of a substrate or a display device, it is known to form a transparent film with a hard coat function on the surface of the substrate or display device. Specifically, a transparent organic resin film or inorganic film is formed on the surface of glass, plastic, or a display device. At this time, it is known that adhesion to the substrate and strength are improved by mixing particles such as silica into the film. When using such particles, it is known to perform surface treatment using an organosilicon compound in order to improve dispersibility into the matrix component (for example, see WO2011/059081).

However, particles surface-treated using an organosilicon compound have a layer in which the OH group on the surface of the particle is chemically bonded to the organosilicon compound, and a layer in which both are physically adsorbed. It is known that the presence of this chemical bonding layer has the effect of suppressing the aggregation of particles in the resin, and it is known that the presence of the physical adsorption layer improves compatibility with the resin (for example, in Japan (See Patent Publication No. 2005-298740 and Japanese Patent Publication No. 2015-189637).

A substrate with a coating containing particles with cavities inside is required to have high hardness and strength. However, if there is an organosilicon compound physically adsorbed to the particles, improvement in hardness and strength is expected due to improved compatibility of the particles with the resin. However, in a substrate provided with a coating using such surface-treated particles, the improvement in hardness and strength is insufficient. The reason is thought to be as follows. In other words, if at least one of the organosilicon compound physically adsorbed and the organosilicon compound free exists with respect to the particle, three-dimensional crosslinking through chemical bonding between the particle and the resin is inhibited, and the density as a film is reduced. Since this becomes insufficient, it is thought that the improvement in hardness and strength of the base material provided with the coating becomes insufficient. Additionally, when a dispersion of such particles is used in an antireflection film, the refractive index increases due to the presence of an organosilicon compound that does not contribute to densification. For this reason, antireflection performance also deteriorates. Therefore, particles in which organosilicon compounds are chemically bonded more precisely are required. Additionally, these particles are required to have high dispersibility in a dispersion medium or resin. Additionally, a substrate equipped with a coating using these particles is required to have sufficient hardness and strength so that particle agglomeration is suppressed.

In order to solve this problem, the inventors discovered the following dispersion of particles. The dispersion according to one aspect of the present disclosure includes particles having an outer shell containing a functional group and silicon, and a cavity inside the outer shell. The average primary particle diameter (D) obtained by image analysis of these particles is 20 to 250 nm. Additionally, the amount of carbon contained in these particles is 0.5 to 10 mass%. Additionally, the amount of the organosilicon compound in the liquid excluding these particles from the dispersion liquid is 0.50 parts by mass or less in terms of solid content with respect to 100 parts by mass of the particles.

Hereinafter, these “particles having an outer shell containing a functional group and silicon and a cavity inside thereof” may simply be referred to as “particles” or “particles in the dispersion.”

These particles have high dispersibility. Additionally, these particles have many polymerization points with matrix forming components. Additionally, these particles contain a small amount of “unreacted” organosilicon compounds that impair anti-reflection performance or inhibit polymerization with matrix forming components. Here, “unreacted” refers to “a state in which the organosilicon compound is only physically adsorbed or a state in which it is free” with respect to the particles. Using a coating liquid containing such particles, a substrate with excellent anti-reflection performance and a coating having high hardness and strength can be obtained.

In order to obtain these surface-treated particles, the inventors discovered the following manufacturing method.

First, a dispersion containing particles having an outer shell containing silicon and a cavity inside the silicon (hereinafter, these may be referred to as “original particles”) is prepared. These particles are surface treated by adding an organosilicon compound represented by the following formula (1) to this dispersion (first step). Next, unreacted organosilicon compounds are removed from the dispersion of particles after surface treatment obtained in the first step (second step).

R _n -SiX _4-n ... Equation (1)

(In the formula, R is an unsubstituted or substituted hydrocarbon group having 1 to 10 carbon atoms, and may be the same or different from each other. Examples of substituents include alkyl group, vinyl group, epoxy group, acryloyl group, (meth)acryloyl group, Examples include an alkoxy group, a mercapto group, a glycidoxy group, a halogen atom, an amino group, a phenyl group, and a phenylamino group. represents an integer of .)

The properties of the surface-treated particles in the dispersion obtained in this second step are similar to the properties of the particles in the dispersion described above. That is, the average primary particle diameter (D) obtained by image analysis of the particles is 20 to 250 nm, the carbon content of the particles is 0.5 to 10% by mass, and the unreacted organosilicon compound in the liquid excluding the particles from the dispersion liquid The amount is 0.50 parts by mass or less in terms of solid content with respect to 100 parts by mass of the particles.

According to the particle dispersion liquid according to one aspect of the present disclosure, a coating liquid capable of producing a film having a low reflectance, excellent adhesion to the substrate, and high hardness and strength is obtained.

[Dispersion of particles]

A dispersion of particles according to the present embodiment (hereinafter, this may simply be referred to as a “dispersion”) will be described.

The particles in the dispersion liquid contain functional groups and silicon on the outer shell of the particles. Additionally, this particle has a cavity inside the outer shell. The average primary particle diameter (D) obtained by image analysis of these particles is 20 to 250 nm. Additionally, the amount of carbon contained in these particles is 0.5 to 10 mass%. Additionally, the amount of the organosilicon compound in the liquid excluding these particles from the dispersion liquid is 0.50 parts by mass or less in terms of solid content with respect to 100 parts by mass of the particles.

By including functional groups in the outer shell of the particles, the dispersibility of the particles in the dispersion medium, the coating liquid for forming a film, or the matrix of the film increases. Therefore, in the substrate provided with a coating using these particles, agglomeration of particles is suppressed. For this reason, a substrate provided with a coating using these particles has sufficient hardness and strength. Additionally, by including silicon in the outer shell of the particle, particles with a low refractive index are obtained. Additionally, the presence of surface OH groups derived from silicon facilitates introduction of the above-mentioned functional groups.

Functional groups contained in the outer shell of these particles include, for example, alkyl group, vinyl group, epoxy group, acryloyl group, (meth)acryloyl group, alkoxy group, mercapto group, glycidoxy group, halogen group, amino group, phenyl group, and phenylamino group. At least one type may be selected. Among these, acryloyl group, (meth)acryloyl group, and epoxy group are preferable because they have high polymerization ability. Therefore, it is preferable that the functional group contained in the outer shell of the particle contains at least one type selected from acryloyl group, (meth)acryloyl group, and epoxy group. These functional groups can be identified by measuring the dried powder of the particles with a Fourier transform infrared spectroscopy device (FT-IR) and analyzing the measurement results.

These functional groups are preferably functional groups derived from an organosilicon compound represented by formula (1). This organosilicon compound can be used, for example, as a raw material used to produce the above-mentioned “original particles,” a surface treatment agent used to treat the surface of the particles, or both. Here, raw materials for producing “original particles” include, for example, alkoxysilanes such as tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), and phenyltrimethoxysilane. However, in particles treated with such a surface treatment agent, many functional groups exist on the outer surface. For this reason, these particles are preferable because they have high dispersibility in coating liquids and films and have sufficient hardness and strength in base materials provided with films.

The average primary particle diameter (D) obtained by image analysis of particles is 20 to 250 nm. This is obtained as follows. That is, the particles are photographed at a predetermined magnification using a transmission electron microscope (TEM). Image processing is performed on any 300 particles in the photo (TEM photo) to determine the area of the particles. The average value of the circular equivalent diameter calculated from the obtained area is the average (D) of the primary particle diameters described above. If the average primary particle diameter (D) is within the above range, the particles can exist in the dispersion without agglomerating or settling. Additionally, the dispersibility of particles in the coating liquid and in the film also improves. Therefore, a film with high transparency, anti-reflection performance, hardness and strength is obtained.

Here, in particles where the average primary particle diameter (D) is less than 20 nm, the proportion of cavities (porosity) occupied by the particles is small, and it is difficult for the refractive index to be sufficiently low. For this reason, anti-reflection performance becomes insufficient. Conversely, if the average primary particle diameter (D) exceeds 250 nm, light scattering is likely to occur and the dispersibility of particles in the coating liquid is low. For this reason, there is a risk that a transparent film may not be obtained. The average (D) of this primary particle diameter is preferably 30 to 250 nm, and more preferably 40 to 120 nm.

The carbon content of the particles can be measured in a carbon sulfur analyzer. For example, centrifugation treatment is used to separate the organosilicon compounds chemically bonded to the particles from the “unreacted” organosilicon compounds. Therefore, only the particles to which the organosilicon compound is chemically bonded are taken out and dried. By measuring the particle powder thus obtained, the carbon content of the particles can be determined.

The carbon content of the particles is 0.5 to 10 mass%. When the carbon content is within this range, the particles can exist in the dispersion without agglomerating or settling. Additionally, the dispersibility of particles in the coating liquid and in the film also improves. Therefore, using these particles, a film with high hardness and strength can be obtained.

Here, if the carbon content is less than 0.5% by mass, sufficient dispersibility and stability may not be obtained, and if these particles are used in a coating, there is a risk that a coating with sufficient hardness and strength may not be obtained. Conversely, even if the carbon content exceeds 10% by mass, the effect of further improving dispersibility and stability and the effect of further improving hardness and strength of the film are unlikely to be obtained. Rather, the refractive index of the particles increases, and anti-reflection performance may become insufficient. This carbon content is preferably 1.0 to 7.0 mass%, more preferably 2.0 to 6.0 mass%.

This carbon content varies depending on the structure and amount of chemically bonded organosilicon compounds. This carbon content is preferably derived from the functional group contained in the outer shell of the particle. Here, for example, when the raw material used to produce the “original particles” does not contain an organosilicon compound and the organosilicon compound of formula (1) is used as a surface treatment agent for the original particles, the above-mentioned particles In order to realize a carbon content of 0.5 to 10% by mass, an organosilicon compound with a solid content (R _n -SiO _(4-n)/2 ) of approximately 1.0 to 30 parts by mass based on 100 parts by mass of the original particles must be used for surface treatment. do.

Here, if the amount of the organosilicon compound used for surface treatment is less than 1.0 parts by mass based on 100 parts by mass of the original particles, sufficient dispersibility and stability cannot be obtained, and when these particles are used in a coating, sufficient hardness and strength are not achieved. There is a risk that the desired film may not be obtained. Conversely, even if this amount exceeds 30 parts by mass, the effect of further improving dispersibility and stability and the effect of further improving hardness and strength of the film are unlikely to be obtained. Rather, the refractive index of the particles increases, and anti-reflection performance may become insufficient. The amount of the organosilicon compound used for surface treatment is preferably 2.0 to 25 parts by mass, more preferably 3.0 to 20 parts by mass. Incidentally, when the “original particles” are produced using an organosilicon compound as a raw material, the “original particles” contain carbon. For this reason, in order to obtain the target carbon content of the particles of this embodiment, the solid content of the organosilicon compound used in surface treatment is lower than that of the “original particles” compared to the case of surface treating “original particles not containing carbon”. It decreases depending on the carbon content of .

The amount of the organosilicon compound in the liquid excluding particles from the dispersion can be calculated from GC-MS measurement. For example, by centrifugal operation, the particles settle, while the unreacted organosilicon compounds that have not reacted with the particles are extracted to the supernatant side. By performing GC-MS measurement on this supernatant, the organosilicon compounds in the liquid excluding particles from the dispersion can be calculated.

The fact that the amount of the organosilicon compound in the liquid excluding the particles from the dispersion liquid is 0.50 parts by mass or less as a solid content with respect to 100 parts by mass of the particles indicates that there is a small amount of unreacted organosilicon compounds. Here, if these unreacted organosilicon compounds exist in excess of 0.50 parts by mass, there is a risk that a film with sufficient hardness and strength may not be obtained when these particles are used in a film. This is because if an unreacted organosilicon compound is present, the degree of polymerization of the matrix forming component during film formation decreases, making it difficult to obtain a dense film. In addition, if an organosilicon compound that does not contribute to densification is present, the refractive index increases, so there is a risk that the anti-reflection performance may also deteriorate. The amount of this organosilicon compound is preferably 0.30 parts by mass or less, more preferably 0.10 parts by mass or less, and even more preferably substantially 0 parts by mass. Here, “substantially 0 parts by mass” means that the organosilicon compound is less than the lower limit of quantification of the measuring device.

In this way, the particles of the present embodiment and their dispersion have an “organosilicon compound having a functional group” that is chemically bonded to the OH group on the particle surface, and the content of “unreacted organosilicon compound” is suppressed, that is, One of the characteristics is that the particles are subjected to “precise surface treatment” using an organosilicon compound.

The refractive index of the particles is preferably 1.08 to 1.38. If the refractive index of the particles is within this range, a transparent film with high anti-reflection performance is obtained. Here, it is difficult to obtain particles with a refractive index of less than 1.08. Conversely, if the refractive index of the particles exceeds 1.38, there is a risk that the anti-reflection performance may become insufficient, although it depends on the refractive index of the substrate or underlayer film. This refractive index is more preferably 1.08 to 1.34, and even more preferably 1.08 to 1.30.

Regarding the content of silicon in the particle, when the total amount of metal elements other than carbon constituting the particle is expressed as 100 parts by mass on an oxide basis, the particle contains 98 parts by mass or more of silicon as silica (SiO ₂ ). It is desirable. If the SiO ₂ content in the particles is 98 parts by mass or more, it becomes easy to obtain a film with low reflectance and high hardness and strength. This SiO ₂ content is more preferably 99 parts by mass or more, further preferably 99.5 parts by mass or more, and particularly preferably 100 parts by mass.

In this way, it is preferable that the constituent components of the particles include silicon (Si) as a main element. Here, the constituent components of the particles may be any of the examples (a) to (c) below. These elements originate from materials suitably used in producing particles.

(a) SiO ₂

(b) An oxide containing Si and at least one element selected from Al, Sn, Sb, Ti, Zr, Zn, Cu, Fe, and In. Additionally, the oxide containing these elements may be a mixture or a complex oxide.

(c) mixture of (a) above and (b) above

However, the content of the particles of elements other than Si in item (b) above is preferably less than 2 parts by mass on the oxide basis when the total amount of metal elements other than carbon constituting the particles is expressed as 100 parts by mass on the oxide basis. . Here, if this content is 2 parts by mass or more, the refractive index of the particles increases, so there is a risk that the reflectance of the film may increase and that a transparent film may not be obtained due to coloring or the like. This content is more preferably less than 1 part by mass, further preferably less than 0.5 parts by mass, and particularly preferably 0 part by mass.

In addition, if the refractive index of the particle is such that it does not deviate from the above-mentioned particle refractive index range, in addition to the particles exemplified in (a) to (c) above, “particles having an outer shell and a cavity inside the particle” and a cavity inside the particle may be used. It does not matter if there are so-called “solid particles” that do not have any. The preferable ratio of these particles different from the particles of the present embodiment also changes depending on the type and composition ratio of the elements constituting the particles. For example, in the case of “solid particles” that, like the particles of this embodiment, contain 98 parts by mass or more of silicon as SiO ₂ and have the same average particle diameter, the number ratio of solid particles to all particles is 10%. It is preferable to be less than. This ratio is obtained, for example, by counting the number of particles and solid particles of this embodiment within a predetermined field of view of a TEM photograph. If this ratio is 10% or more, there is a risk that the refractive index will be higher than the desired range. In this case, when a coating liquid containing such particles is formed into a film, the desired anti-reflection performance is not obtained. The number ratio of these solid particles is more preferably less than 5%, still more preferably less than 2%, particularly preferably less than 1%, and most preferably 0%. If particles of other element species exist, for example, mapping is performed on the particles within a predetermined field of view using energy dispersive X-ray analysis (EDS) to determine the number of particles of the present embodiment and particles of other element species. By counting, the particle ratio of this embodiment and the ratio of particles different from it are obtained.

The ratio (A1/ A2) is preferably 0.80 or less. The fact that the ratio (A1/A2) is in this range indicates that the functional group derived from the organosilicon compound is sufficiently introduced to the particle surface and that there is little unreacted organosilicon compound in the dispersion liquid. When such particles are used, the dispersibility of the particles in the coating liquid and in the film also improves. Therefore, a film with high transparency, hardness, and strength is obtained.

Here, if the ratio (A1/A2) exceeds 0.80, there is a risk that the introduction of the functional group derived from the organosilicon compound to the particle surface is insufficient, and there is a risk that a large amount of unreacted organosilicon compounds may exist in the dispersion liquid. . The lower limit of the ratio (A1/A2) is not particularly set, but is, for example, 0.10, considering the functional groups of the surface treatment agent that can react with the OH groups on the particle surface. This ratio (A1/A2) is more preferably 0.55 or less, and even more preferably 0.40 or less.

In the measurement method called pulse NMR described above, magnetization in a state of thermal equilibrium within a static field is excited by irradiating radio waves of several tens of MHz on pulses. Then, the phenomenon in which the excited magnetization returns to its original thermal equilibrium state with the passage of time is observed. Liquid molecules that are in contact with or adsorbed on the particle surface and liquid molecules in a free state that are not in contact with the particle surface have different responses to changes in the magnetic field.

In general, the movement of liquid molecules adsorbed on the particle surface is restricted. Meanwhile, liquid molecules that are not adsorbed on the particle surface can move freely. As a result, the relaxation time of the liquid molecules adsorbed on the particle surface becomes shorter than the relaxation time of other liquid molecules. The relaxation time observed in the liquid in which the particles are dispersed is the average of the two relaxation times, reflecting the volume concentration of the liquid on the particle surface and the volume concentration of the liquid in the free state.

In the dispersion of particles surface-treated with an organosilicon compound, there may be unreacted organosilicon compounds that are not chemically bonded to the particles in addition to the organosilicon compounds chemically bonded to the particles. The molecular weight of these organosilicon compounds is very small compared to the particles. Because of this, these organosilicon compounds have a very large specific surface area. Additionally, with respect to the particles in the dispersion liquid, the movement of the liquid molecules adsorbed to these unreacted organosilicon compounds is restricted. For this reason, when unreacted organosilicon compounds are present in the dispersion, the measured relaxation time becomes shorter, that is, the specific surface area calculated from the relaxation time becomes a large value.

By the way, the specific surface area (A1) of the particles in the dispersion obtained from pulse NMR measurement represents the specific surface area of the particles in the part wetted by the dispersion medium. In particles surface-treated with an organosilicon compound, there are fewer OH groups on the particle surface than on the original particles due to a reaction between the organosilicon compound and the OH groups on the particle surface. For this reason, the specific surface area of the particles in the portion wetted by the hydrophilic dispersion medium becomes a small value. In contrast, in unreacted organosilicon compounds and particles in which only organosilicon compounds are physically adsorbed, relatively large amounts of OH groups remain. For this reason, when they exist in the dispersion liquid, the specific surface area of the part wetted by the hydrophilic dispersion medium becomes a large value. In this regard, the value of this specific surface area (A1) also changes depending on the degree of surface treatment (chemical bonding) using an organosilicon compound to the particles and the amount of unreacted organosilicon compounds in the dispersion. Additionally, the value of the specific surface area (A1) also changes depending on the type of dispersion medium at the time of measurement.

Therefore, the ratio (A1/A2) is an indicator of the amount of the functional group derived from the organosilicon compound introduced to the particle surface and the amount of the unreacted organosilicon compound in the dispersion.

The specific surface area (A1) of the particles is obtained by equation (3) using the volume concentration (Ψp) of the particles determined in equation (2) below.

Ψp=(Sc/Sd)/[(1-Sc)/Td] … Equation (2)

(However, in the formula, Sc represents the particle solid concentration (mass %) of the dispersion. Sd represents the density of the particles (g/cm3). Td represents the density of the dispersion medium (g/cm3) at 25°C. .)

Here, the solid content concentration is the concentration obtained by converting the particles into the solid content in the dispersion (the same applies hereinafter). Sd is calculated as the sum of the density of the components of the outer shell of the particle multiplied by their volume ratio and the density of the components present in the cavity of the particle multiplied by their volume ratio. As the component density used to calculate Sd, for example, the components of the outer shell of the particle are 2.2 in the case of silica, 3.9 in the case of alumina, 6.9 in the case of tin oxide, 5.2 in the case of antimony (V) oxide, and titania. (anatase) 3.9, titania (rutile) 4.3, zirconia 6.0, zinc oxide 5.6, copper(II) oxide 6.3, iron(III) oxide 5.2 , in the case of indium oxide, 7.2 is used (unit is g/cm3). Additionally, when the constituents of the outer shell of the particle are composite oxide particles, particles containing mixed oxides, or a mixture of oxide particles, Sd can be calculated according to the ratio of the oxides. Additionally, when the component present in the cavity of the particle is air, a component density of 0.0 g/cm3 is used to calculate Sd. Even if the components present in the particle cavity are other gases or liquids, their corresponding densities are used to calculate Sd. For example, in the case of the particles of this embodiment having an outer shell containing silicon and a cavity inside the cavity, porosity is used as the volume ratio of the cavity. The porosity of a particle is defined as the ratio of voids in the particle to the particle. Specifically, first, a TEM photo of the particle is taken. At this time, because the density of the hollow portion of the particle is low, the contrast of that portion becomes low. Conversely, because the density of the outer shell portion is high, the contrast of that portion becomes high. The hollow portion and outer shell portion of the particle can be identified (distinguished) using this difference in contrast. More specifically, image processing is performed on any 300 particles in the TEM photo, the area of the cavity is determined, the equivalent circle diameter is determined from the obtained area, and this is taken as the average of the diameters of the cavity. At this time, assuming that the particle shape is a true sphere, the average volume of the primary particle and the average volume of the cavity are calculated. Porosity is expressed as the ratio of the average volume of the cavity to the average volume of these primary particles. Additionally, as the value of Td, for example, when the dispersion medium is methanol, 0.79 g/cm3 is used. If different types of dispersion media or mixtures of dispersion media are used, the corresponding densities are used.

A1={[(Ra/Rb)-1]×Rb}/(Ka×Ψp) … Equation (3)

(However, in the formula, A1 represents the specific surface area (m2/g) of the particle. Ra represents the reciprocal of the pulse NMR relaxation time in the measurement of the dispersion. Rb represents the relaxation of the pulse NMR in the measurement of the dispersion medium. Ka represents the reciprocal of time. Ka represents the coefficient depending on the dispersion medium and particles used.)

The coefficient Ka is calculated by ensuring that the specific surface area (A2) of the particles obtained from the average (D) of the primary particle diameters of the particles and the specific surface area (A3) of the particles obtained by pulse NMR measurement of the particle dispersion are equal to each other. .

Regarding the specific surface area (A2) of the particles, the specific surface area (A2) can be obtained by the following equation (4) using the average (D) of the primary particle diameters of the particles.

A2=6000/Sd/D … Equation (4)

(In the formula, Sd represents the density of particles (g/cm3).)

The specific surface area (A3) of the particles is obtained by equation (5) using the particle volume concentration (Ψp) obtained in equation (2).

A3={[(Rc/Rd)-1]×Rd}/(Ka×Ψp) … Equation (5)

(However, in the formula, A3 represents the specific surface area (m2/g) of the particle. Rc represents the reciprocal of the relaxation time of pulse NMR in the measurement of the particle dispersion. Rd represents the pulse NMR in the measurement of the dispersion medium. Ka represents the reciprocal of the relaxation time and represents a coefficient depending on the dispersion medium and particles used.)

Here, the coefficient Ka is set so that the specific surface area (A2) and the specific surface area (A3) are the same value, so from equations (4) and (5),

Ka={[(Rc/Rd)-1]×Rd}/(Ψp×A2) … Equation (6)

It can be obtained as

The dispersion medium and concentration of the dispersion liquid are not particularly limited as long as the particles are stably dispersed in the liquid without agglomerating or settling.

Examples of the dispersion medium include water, alcohols, esters, glycols, ethers, ketones, and aprotic polar solvents. These may be used individually, or two or more types may be mixed and used.

Regarding the concentration of the dispersion, it is preferable that the solid content concentration of the particles is 1 to 40 mass%. Here, if the solid content concentration is less than 1% by mass, there is a risk that processing will take time when producing the coating liquid. Conversely, if the solid content concentration exceeds 40% by mass, there is a risk that the stability of the dispersion may decrease. The concentration of the dispersion is more preferably 5 to 35% by mass, and even more preferably 10 to 30% by mass.

The content of each element belonging to alkali metal and alkaline earth metal, which are impurities in the particles, is preferably 500 ppm or less per particle when the element is expressed as an oxide. If their content is small, the coalescence of particles decreases. For this reason, the stability of the dispersion liquid and the coating liquid increases. Additionally, because the particles are uniformly dispersed in the coating liquid or film, a film with high hardness and strength is obtained.

Here, if the content of the above-described impurity elements is greater than 500 ppm, the rate at which particles coalesce increases. For this reason, there is a risk that sufficient stability of the dispersion liquid and coating liquid may not be obtained, and that sufficient hardness and strength of the film may not be obtained. The content of the above impurity elements is more preferably 100 ppm or less. Additionally, alkali metal refers to Li, Na, K, Rb, Cs, and Fr. Additionally, alkaline earth metals refer to Be, Mg, Ca, Sr, Ba, and Ra.

In addition, it is preferable that the content of each of the impurities in the particles, such as Pd, Ag, Mn, Co, Mo, Ni, and Cr, is less than 100 ppm. Additionally, it is preferable that the respective contents of U and Th are less than 0.3 ppb. If the content of these elements increases, there is a risk that the dispersion may be colored and a film with the desired refractive index may not be obtained.

In addition, when particles are used in semiconductor circuits such as highly integrated logic or memory that require high purity, or in optical sensors, etc., elements such as Pd, Ag, Mn, Co, Mo, Ni, and Cr, as well as the above-mentioned For elements such as Al, Sn, Sb, Ti, Zr, Zn, Cu, Fe and In, it is preferable that the respective content is less than 0.1 ppm. If the content of these elements is 0.1 ppm or more, the metal elements may cause insulation defects in the circuit or short-circuit the circuit, and there is a risk that the light transmittance may decrease. As a result, there is a risk that the dielectric constant of the insulating film may decrease, the impedance of the metal wiring may increase, the response speed may be delayed, and power consumption may increase. In particular, U and Th generate radioactivity. For this reason, their presence even in trace amounts is undesirable because it may cause malfunction of the semiconductor due to radiation.

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

Methods for obtaining high-purity particles include preparing raw materials low in these elements in advance or suppressing the incorporation of these elements from the particle production equipment, as described above. In addition, it is possible to reduce these elements from particles manufactured without sufficiently taking such measures.

The shape of the particle and the shape of the cavity are not particularly limited. For example, these shapes include spherical shape, elliptical sphere (rugby ball) shape, cocoon shape, star candy shape, chain shape, and rosy shape. Among them, spherical particles are preferable because they have high dispersibility and can be uniformly dispersed in the film.

Additionally, the cavity inside the outer shell preferably has a shape that follows the outer shape of the particle. Although it varies depending on the thickness of the outer shell, when stress is applied to the particle, sufficient hardness and strength can be obtained if the outer shell has a uniform thickness. Furthermore, it is preferable that the shape of the cavity is spherical similar to that of the spherical particle.

It is preferable that this cavity is substantially one cavity in order to lower the refractive index and obtain a transparent film. Here, “substantially one cavity” means that “particles with a plurality of cavities inside the outer shell” may be included due to particle coalescence, etc., but “the ratio of particles with one cavity inside the outer shell” 」means that it is more than 90%. The “number ratio of particles with one cavity inside the outer shell” is preferably 95% or more, more preferably 98% or more, even more preferably 99% or more, and most preferably 100%.

The porosity of the particles is preferably 10 to 80%. However, the porosity of the particles is not particularly limited as long as the above-mentioned refractive index is satisfied. Here, if the porosity of the particles is less than 10%, the refractive index is not sufficiently lowered, and thus the anti-reflection performance becomes insufficient. Conversely, if the porosity of the particles exceeds 80%, there is a risk that hardness and strength may decrease. The proportion of voids in these particles is more preferably 20 to 70%, and even more preferably 25 to 60%.

[Method for producing dispersion of particles]

The method for producing a particle dispersion according to the present embodiment involves surface-treating “particles having an outer shell containing silicon and a cavity inside the original particle” using an organosilicon compound represented by formula (1). It sequentially includes a first step and a second step of removing unreacted organosilicon compounds from the dispersion of surface-treated particles obtained in the first step. As a result, a dispersion of particles having an outer shell containing functional groups and silicon and a cavity inside the shell is obtained.

Since the particles produced in this way have suppressed aggregation, they have sufficient antireflection performance, hardness, and strength when used in a coating film. Below, each process is explained.

[First process]

In this process, “original particles” are prepared as starting materials. Here, the “original particle” may be any of the particles listed in the following (d) to (f). In addition, these particles may be produced by conventionally known methods (for example, patent documents 2 and 3).

(d) Particles having an outer shell containing SiO ₂ and a cavity inside the shell.

(e) Particles having an outer shell containing an oxide containing Si and at least one element selected from Al, Sn, Sb, Ti, Zr, Zn, Cu, Fe, and In, and a cavity inside the shell. The oxide containing these elements may be a mixture or a complex oxide.

(f) a mixture of the particles of (d) above and the particles of (e) above

The silicon content contained in these “original particles” is not particularly limited as long as the silicon content of the final particles surface-treated with an organosilicon compound falls within an appropriate range, as will be described later. For example, when the total amount of metal elements other than carbon constituting the particles is expressed as 100 parts by mass on an oxide basis, the final particles obtained preferably contain 98 parts by mass or more of silicon as SiO ₂ . This silicon content is more preferably 99 parts by mass or more, further preferably 99.5 parts by mass or more, and particularly preferably 100 parts by mass.

Regarding the average (F) of the primary particle diameter obtained by analyzing the image of the “original particle,” the average (D) of the primary particle diameter obtained by analyzing the image of the finally obtained particle is within an appropriate range (20 to 250 nm). There is no particular limitation as long as it is included.

In surface treatment, a dispersion of “original particles” is first prepared. As a dispersion medium, it is preferable to use alcohols such as methanol and ethanol. Here, a predetermined amount of the organosilicon compound represented by formula (1) is added, and the organosilicon compound is hydrolyzed. In this hydrolysis, it is also possible to add water as needed. The ratio (Mw/Mo) of the number of moles of water (Mw) used and the number of moles (Mo) of the organosilicon compound is preferably 1 or more. Here, when the ratio (Mw/Mo) is less than 1, there is a risk that hydrolysis may become insufficient and the hardness, strength, transparency, haze, etc. of the film may become insufficient. The upper limit of the ratio (Mw/Mo) is not specifically set. However, if the ratio (Mw/Mo) exceeds 200, there is a risk that the hydrolysis reaction becomes intense and the organosilicon compounds polymerize with each other, making it difficult to realize efficient organosilicon compound treatment on the particle surface. This ratio (Mw/Mo) is more preferably 1 to 100.

In addition, in this hydrolysis, it is also possible to use an acid or an alkali as a catalyst for hydrolysis, if necessary. The catalyst for hydrolysis is preferably ammonia. This is because even if ammonia remains in the dispersion, it is easy to remove, so the stability of the dispersion is easy to maintain. The ratio (M _N /Mo) of the number of moles of ammonia (M _N ) used and the number of moles (Mo) of the organosilicon compound is preferably in the range of 0.005 to 5. Here, when the ratio (M _N /Mo) is less than 0.005, there is a risk that hydrolysis becomes insufficient and the hardness, strength, transparency, haze, etc. of the film become insufficient. If this ratio (M _N /Mo) exceeds 5, there is a risk that the hydrolysis reaction becomes more intense and the organosilicon compounds polymerize with each other, making it difficult to realize efficient organosilicon compound treatment on the particle surface.

Surface treatment is preferably performed in a uniform system. In addition, in the surface treatment, in order to promote chemical bonding between the particles and the organosilicon compound, it is preferable to perform heating for 0.5 to 48 hours at a temperature below the boiling point of the dispersion medium (e.g., room temperature to 120°C). .

When used on a substrate with a coating, the particles in which the surface of the particle is chemically bonded to an organosilicon compound through this surface treatment have high adhesion to the substrate and high hardness and strength.

Examples of the organosilicon compound include those shown in Table 1. These organosilicon compounds may be contained alone in the particles, or may be contained in plural types of particles. In surface treatment, it is possible to use these organosilicon compounds individually or to mix and use multiple types of organosilicon compounds. In addition, it is also possible to process the same type of organosilicon compound in stages, to process a mixture of multiple types of organosilicon compounds in stages, and to process multiple types of organosilicon compounds separately and in stages. do.

[Second process]

The organosilicon compound used for surface treatment in the first step may contain unreacted organosilicon compounds in addition to the organosilicon compounds chemically bonded to the particles. In the second step, the purpose is to remove such “unreacted organosilicon compounds with respect to the particles.” Methods for removing unreacted organosilicon compounds from surface-treated particles include, for example, ultrafiltration membrane methods, centrifugation methods, and distillation methods. Among them, the ultrafiltration membrane method is preferable because of its high removal efficiency. Additionally, ultrasonic treatment may be combined for the purpose of separating the organosilicon compound, which is merely physically adsorbed to the surface-treated particles, from the surface-treated particles.

In order to efficiently perform this “removal of unreacted organosilicon compounds,” it is preferable that the concentration of the dispersion liquid of the particles surface-treated in the first step is 5 to 40% by mass in terms of solid content. Here, if this concentration is less than 5% by mass, the amount of cleaning liquid used in the second process increases with respect to the obtained surface-treated particles, and productivity deteriorates. Conversely, if this concentration exceeds 40% by mass, there is a risk that thickening or gelation may occur during the second process.

In addition, the amount of the cleaning liquid used for “removal of unreacted organosilicon compounds” varies depending on the amount of the dispersion of particles surface-treated in the first step and the concentration of the dispersion, but the dispersion of particles surface-treated in the first step is 3. It is desirable to have more than twice that. Here, if the amount of the cleaning liquid is less than 3 times, there is a risk that “removal of unreacted organosilicon compounds” may become insufficient. There is no particular upper limit to this amount of cleaning liquid. However, even if 10 times more washing liquid is used, “removal of unreacted organosilicon compounds” is not significantly improved. As this cleaning liquid, it is preferable to use the same type of dispersion medium used in the first step.

The dispersion finally obtained in the second step contains particles having an outer shell containing silicon and a functional group derived from an organosilicon compound of formula (1), and a cavity inside the shell. The average primary particle diameter (D) obtained by image analysis of these particles is 20 to 250 nm, and the carbon content is 0.5 to 10 mass%. Additionally, from the dispersion liquid, the amount of the organosilicon compound in the liquid excluding these particles is 0.50 parts by mass or less in terms of solid content with respect to 100 parts by mass of the particles.

With this manufacturing method, “precise surface treatment” can be realized. In this “precise surface treatment,” the particle dispersion has an “organosilicon compound having a functional group” that is chemically bonded to the OH group on the particle surface. Additionally, in this dispersion, the content of “unreacted organosilicon compounds” that may reduce performance is suppressed.

The amount of surface treatment may be such that a desired amount of an organosilicon compound is chemically bonded to the surface of the particles, and the carbon content of the particles finally obtained is within an appropriate range (0.5 to 10% by mass). This carbon content varies depending on the structure and amount of chemically bonded organosilicon compounds. Here, when the raw material used to produce the “original particle” does not contain an organosilicon compound and the organosilicon compound of formula (1) is used as a surface treatment agent for the original particle, the carbon content of the above-mentioned particle is 0.5 In order to achieve from 10% by mass, approximately 1.0 to 30 parts by mass of an organosilicon compound with a solid content (R _n -SiO _(4-n)/2 ) is used for surface treatment, based on 100 parts by mass of the original particles. Of course, when an organosilicon compound is used in producing the “original particle,” and the carbon is present in the “original particle,” that much carbon is also added as the carbon content of the final particle obtained. Therefore, in order to obtain the target carbon content of the particles of this embodiment, the solid content of the organosilicon compound used in surface treatment is lower than that of the “original particles” compared to the case of surface treating “original particles not containing carbon”. It decreases depending on the carbon content of . That is, the particles in the dispersion obtained in the second step contain 1.0 to 30 parts by mass of an organic silicon compound having a functional group as a solid content relative to 100 parts by mass of the particles before surface treatment in the first step.

However, although there may be cases depending on the difference in the amount of surface treatment, in one operation from the first step to the second step, the above-mentioned “amount of organosilicon compound having a functional group contained in the particles” and “the amount excluding the particles from the dispersion” In some cases, it is difficult for the two “amount of organosilicon compounds in the liquid” to fall within an appropriate range. Therefore, although it varies depending on the reaction efficiency between the OH group on the particle surface and the organosilicon compound, in order to advance the chemical reaction between the OH group on the particle surface and the organosilicon compound and efficiently obtain the target particle, the first step is followed by the second step. After performing the process, it is preferable to repeat the process from the first process to the second process multiple times. Furthermore, “precise surface treatment” can be realized more efficiently if the surface treatment amount per treatment is lower than the final target amount and the process is repeated.

In addition, the physical properties of the particles and their dispersion finally obtained in the second step and the preferable ranges of these properties are the same as those of the particles and their dispersion described above.

[Coating liquid for film formation]

The particles of this embodiment can be applied to a coating liquid for forming a film. This coating liquid contains particles, a matrix forming component, and a dispersion medium. This dispersion medium contains at least one of water and an organic dispersion medium. In addition to these, this dispersion medium may contain additives such as a polymerization initiator, leveling agent, and surfactant.

The concentration of particles in the coating liquid is preferably 5 to 95% by mass in terms of solid content, based on the total amount of solid content such as particles and matrix forming components. Here, if the particle concentration is less than 5% by mass, there is a risk that the refractive index of the film cannot be sufficiently reduced. Conversely, if the particle concentration is more than 95% by mass, there is a risk that cracks may occur in the film, adhesion to the substrate may become insufficient, and hardness, strength, transparency, haze, etc. may deteriorate. The concentration of these particles is more preferably 10 to 85 mass%, and even more preferably 20 to 70 mass%.

Matrix forming components include inorganic matrix forming components and organic resin-based matrix forming components. Examples of matrix forming components include polycondensates of organosilicon compounds, ultraviolet curable resins, thermosetting resins, and thermoplastic resins.

Examples of ultraviolet curable resins include (meth)acrylic resins, γ-glycidyloxy resins, urethane resins, and vinyl resins.

Thermosetting resins include urethane resin, melamine resin, silicon resin, butyral resin, reactive silicone resin, phenol resin, epoxy resin, unsaturated polyester resin, and thermosetting acrylic resin.

Thermoplastic resins include polyester resin, polycarbonate resin, polyamide resin, polyphenylene oxide resin, thermoplastic acrylic resin, vinyl chloride resin, fluorine resin, vinyl acetate resin, and silicone rubber.

These resins may be two or more types of copolymers or modified products, and may be used in combination. Additionally, these resins may be emulsion resins, water-soluble resins, or hydrophilic resins.

The components forming these resins are preferably monomers or oligomers from the viewpoint of particle dispersibility and ease of coating.

The concentration of the matrix forming component in the coating liquid is preferably 5 to 95% by mass in terms of solid content relative to the total amount of solid content such as particles and matrix forming components contained. Here, if the concentration of the matrix forming component is less than 5% by mass, encapsulation is difficult. Furthermore, even if a film is obtained, there is a risk that cracks may occur in the film, adhesion to the substrate may become insufficient, and hardness, strength, transparency, haze, etc. may deteriorate. Conversely, if the concentration of the matrix forming component is more than 95% by mass, there is a risk that the refractive index may not be sufficiently reduced because the amount of particles is small. The concentration of this matrix forming component is more preferably 15 to 90% by mass, and even more preferably 30 to 80% by mass.

As an organic dispersion medium, one that can uniformly disperse particles and dissolve or disperse additives such as matrix forming components and polymerization initiators is used. Among them, a hydrophilic dispersion medium and a polar dispersion medium are preferable. As shown in Table 2, examples of hydrophilic dispersion media include alcohols, esters, glycols, and ethers. Additionally, examples of polar dispersion media include esters, ketones, and aprotic dispersion media. These may be used individually, or two or more types may be mixed and used.

As additives, those conventionally used for film formation can be used arbitrarily. For example, to promote polymerization of matrix forming components and improve film forming properties, polymerization initiators, leveling agents, etc. are used as additives.

Examples of the polymerization initiator include those shown in Table 3.

Examples of the leveling agent include acrylic leveling agents, silicone leveling agents, and acrylic silicone leveling agents. As these leveling agents, those having a fluorine group are preferably used from the viewpoint of strength improvement.

Regarding the concentration of these additives in the coating liquid, for convenience, what is contained as solid content when encapsulated is counted as a matrix forming component, and after encapsulation, it is counted 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 relative to the coating solution) is preferably 0.1 to 60% by mass.

Here, if the solid content concentration of the coating liquid is less than 0.1% by mass, there is a risk that productivity may decrease because processing takes time when manufacturing a base material with a coating film. Conversely, if the solid content concentration of the coating liquid is higher than 60% by mass, there is a risk that the stability of the coating liquid may decrease. Additionally, because the viscosity of the coating liquid increases, there is a risk that coatability may decrease. The solid content concentration of the coating liquid is more preferably 1 to 50 mass%.

[Substrate with film]

Using the above-mentioned coating liquid, a film is formed on the substrate. A substrate provided with such a film is used, for example, in display devices that require transparency.

Specifically, after applying the coating liquid on the substrate, drying and ultraviolet ray irradiation are performed to form a film on the substrate. The method of applying the coating liquid is not particularly limited as long as it is a method that can form a film on the substrate. For example, known methods such as spray method, spinner method, roll coat method, bar coat method, slit coater printing method, gravure printing method, and micro gravure printing method can be adopted. In drying, the coating liquid is heated to, for example, about 50 to 150°C, and the dispersion medium is removed by evaporation. Thereafter, by irradiating ultraviolet rays, polymerization of the resin component is promoted and hardening of the film is attempted. The film is mainly formed of a matrix (resin) component and particles.

In a coating, the solid content ratio of the particles and matrix forming components in the coating liquid becomes the ratio of the particle components and matrix in the coating as it is. As described above, among the additives in the coating liquid, those remaining as solid content are considered as matrix.

The film thickness of the film can be appropriately selected depending on the application. For example, if it is a transparent film, the film thickness is preferably 80 to 350 nm. Here, if the film thickness is thinner than 80 nm, the hardness and strength of the film may become insufficient. Additionally, there are cases where the film is too thin and sufficient anti-reflection performance cannot be obtained. Conversely, if the film thickness is thicker than 350 nm, cracks are likely to form in the film, so the strength of the film may become insufficient. Additionally, if the film is too thick, anti-reflection performance may deteriorate. This film thickness is more preferably 85 to 220 nm, and even more preferably 90 to 110 nm.

The refractive index of the transparent film is preferably 1.10 to 1.45. Here, it is difficult to obtain a transparent film with a refractive index of less than 1.10. If the refractive index of the transparent film exceeds 1.45, the antireflection performance may become insufficient, depending on the refractive index of the base material or the refractive index of other films formed as necessary under the transparent film. The refractive index of the transparent film is more preferably 1.10 to 1.40, and even more preferably 1.10 to 1.35.

It is preferable that the light transmittance of the substrate provided with the film is 85.0% or more. Here, if the light transmittance is less than 85.0%, there is a risk that image clarity may become insufficient in display devices, etc. This light transmittance is more preferably 90.0% or more.

Additionally, the haze of the base material provided with the coating film is preferably 2.0% or less, and more preferably 0.5% or less.

Additionally, the reflectance of the base material provided with the coating film is preferably 2.0 or less, more preferably 1.5% or less, further preferably 1.0% or less, and particularly preferably 0.7% or less.

The strength of the film is evaluated by sliding #0000 steel wool on the film 50 times under the conditions of a predetermined load/cm2. When this predetermined load is 500 g, it is desirable that no striped flaws are observed on the film surface. Regarding this strength, more preferably, no scratches are observed when the predetermined load is 800 g, and even more preferably, no scratches are observed when the predetermined load is 1200 g.

The hardness of the film is preferably 2H or more. Here, if the hardness of the film is less than 2H, the hardness is insufficient as a hard coat film. This hardness is more preferably 3H or more, and even more preferably 4H or more.

As a base material, a known material can be used. From the viewpoints of transparency, flexibility, toughness, etc., transparent resin substrates such as polycarbonate, acrylic resin, polyethylene terephthalate, triacetylcellulose (TAC), polymethyl methacrylate resin, and cycloolefin polymer are preferable. The thickness of the base material is not particularly limited, but considering durability and handling properties, it is preferably 10 to 100 μm, and more preferably 20 to 80 μm.

The adhesion between the film and the substrate is evaluated, for example, as follows. First, a scratch is created in the shape of a square using a knife on the surface of the base material provided with the film. After adhering a cellophane tape to this surface, the cellophane tape is peeled off. The greater the number of remaining cells, the more likely it is that the film will not peel off from the substrate. Therefore, the larger the number of remaining compartments, the higher the adhesion between the film and the substrate, so it is preferable.

Additionally, as such a substrate, a substrate provided with a coating film on which another coating film is formed can also be used. Examples of other films include conventionally known hard coat films, primer films, high refractive index films, and conductive films.

Hereinafter, examples of this embodiment will be described.

[Example 1]

<Preparation of particle dispersion>

After adding 99,500 g of pure water to 500 g of an aqueous dispersion of silica particles (USB-120 manufactured by Nikki Shokubai Kasei Co., Ltd., average particle diameter of 25 nm, solid content concentration of 20 mass%, Al ₂ O ₃ content in solid content of 27 mass%), An aqueous solution of sodium hydroxide with a concentration of 1% by mass was added, and the pH was adjusted to 11.0. Thereafter, the obtained solution was heated to 98°C, and 18.7 kg of an aqueous sodium silicate solution with a concentration of 1.5% by mass as SiO ₂ and 18.7 kg of an aqueous solution of sodium aluminate with a concentration of 0.5% by mass as Al ₂ O ₃ were added to the solution. did. Afterwards, washing was performed by centrifugal sedimentation to obtain a dispersion of complex oxide particles (a1). The average particle diameter of this composite oxide particle (a1) was 46 nm.

The dispersion of the composite oxide particles (a1) was heated to 98°C, and 63.1 kg of an aqueous sodium silicate solution with a SiO ₂ concentration of 1.5 mass% and 21.0 kg of an aqueous sodium aluminate solution with an Al ₂ O ₃ concentration of 0.5 mass% were added to the mixture. , was added to the dispersion. Afterwards, the solid content concentration of the dispersion was adjusted to 13% by mass by washing using an ultrafiltration membrane. Thereafter, the dispersion was filtered through a capsule filter with an eye size of 1 μm, thereby obtaining a dispersion of composite oxide particles (b1). The average particle diameter of this composite oxide particle (b1) was 61 nm.

To 5000 g of the dispersion of the composite oxide particles (b1), 11250 g of pure water was added, and concentrated hydrochloric acid (concentration 35.5% by mass) was added dropwise to adjust the pH to 1.0. To this dispersion, 10 L of a pH 3 hydrochloric acid aqueous solution and 5 L of pure water were added, and the aluminum salt dissolved in the dispersion was separated and washed using an ultrafiltration membrane. As a result, silica-based particles (c1) with a concentration of 10% by mass were obtained.

Next, aqueous ammonia was added to 500 g of the dispersion of silica-based particles (c1), the pH of the dispersion was adjusted to 10.6, and the dispersion was transferred to a pressure-resistant container. Next, the dispersion was heated to 200°C and held for 10 hours, then cooled to room temperature. After that, the dispersion was subjected to ion exchange for 3 hours using 800 g of a cation exchange resin (Dia Ion SK1B manufactured by Mitsubishi Chemical Corporation), followed by an anion exchange resin (Diamond manufactured by Mitsubishi Chemical Corporation). Ion exchange was performed for 3 hours using 400 g of ion SA20A). Afterwards, using 400 g of cation exchange resin (Diaion SK1B manufactured by Mitsubishi Chemical Corporation), the dispersion was subjected to ion exchange at 80°C for 3 hours and washed, thereby forming an “outer shell containing silicon.” and particles having cavities inside them (original particles)” (P1) was obtained.

By replacing the solvent of the aqueous dispersion of the particles (P1) with methanol using an ultrafiltration membrane, a methanol dispersion of the particles (P1) with a solid content concentration of 20% by mass was prepared.

<Surface treatment of particles with an organosilicon compound (first process)>

To 200 g of the methanol dispersion of the particles (P1), 0.4 g of ammonia water with a concentration of 28% by mass and 4.0 g of pure water were added, and this dispersion was stirred at room temperature for 0.5 hours.

Next, 8 g of γ-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) as an organosilicon compound was added to this dispersion (solid content (R) relative to 100 parts by mass of particles (P1)) 20 parts by mass as _n -SiX _4-n ) was added. Thereafter, this dispersion was stirred at 50°C for 6 hours to obtain a dispersion of surface-treated particles (S1).

<Removal of organosilicon compounds (second process)>

This dispersion of particles (S1) was cooled to room temperature, and using 1 kg of methanol (corresponding to 5 times the amount of methanol dispersion of particles (S1)), an ultrafiltration membrane method was used to extract “unreacted organosilicon compounds.” 」 was removed. In this way, a methanol dispersion of the particles (R1) of this embodiment with a solid content concentration of 20% by mass was produced.

The particles and their dispersion were measured by the following method.

The characteristics of each particle manufacturing process and the properties of the particles and dispersions are shown in Tables 4 and 5 (the same applies to the examples and comparative examples below).

(1) Functional groups included in the outer shell of particles

The presence or absence of functional groups contained in the particle shell and their types were determined by the following method.

First, the dispersion was dried in an evaporator and then at 150°C. The obtained dry powder was subjected to measurement based on a diffuse reflection method using a Fourier transform infrared spectroscopy device (FT-IR) (FT/IR-6100 manufactured by Nippon Bunko Co., Ltd.) to detect peaks. At this time, the wavenumber range was set to 700 cm ^-1 to 4000 cm ^-1 , the TGS was used as a detector, the resolution was set to 4.0 cm ^-1 , and the number of integrations was 50, and measurements were made. Then, based on the detected peak, the functional group was specified by referring to the organic compound spectrum database SDBS (https://sdbs.db.aist.go.jp (National Institute of Advanced Industrial Science and Technology, 2021.01)). did.

(2) Carbon content

The dispersion was centrifuged for 30 minutes using a small ultracentrifuge (CS150GXL manufactured by Hitachi Koki Co., Ltd.) under the conditions of a temperature of 10°C and a rotation speed of 1,370,000 rpm (1,000,000 G). The precipitate of the obtained treatment liquid was collected and dried under vacuum at 120°C for 24 hours to obtain particle powder. For this powder, the carbon content of the particles was measured using a carbon sulfur analyzer (CS844 manufactured by LECO Japan).

(3) Amount of organosilicon compound in liquid excluding particles from dispersion liquid

The dispersion was centrifuged in the same manner as above using a small ultracentrifuge (CS150GXL manufactured by Hitachi Koki Co., Ltd.). The supernatant of the obtained treatment liquid was recovered, the amount of organosilicon compounds in the supernatant excluding particles was measured using a heat extraction gas chromatograph (Agilent5977BGC/MSD, manufactured by Agilent Technology Co., Ltd.), and the measured amount of organosilicon compounds was calculated as , calculated as a value for 100 parts by mass of particles.

(4) Average of primary particle diameter of particles (D)

The particle dispersion was diluted to 0.01% by mass and then dried on the collodion film of a copper cell for electron microscopy. Next, this was photographed at a predetermined magnification using a field emission type transmission electron microscope (HF5000 manufactured by Hitachi High Technologies Co., Ltd.). For any 300 particles in the obtained photographic projection (TEM photo), the area of the particles was determined through image processing, and the equivalent circle diameter was determined from the area. The average value of the equivalent circle diameter was taken as the average (D) of the primary particle diameters of the particles.

(5) Particle shape and number ratio of solid particles

In the same manner as the average (D) of the primary particle diameters of the particles described above, the shape of the particles and the number ratio of solid particles to all particles were obtained from the TEM photograph.

In addition, the shape of the particles produced this time was spherical in both Examples and Comparative Examples.

(6) Refractive index

The methanol dispersion of the particles was placed in an evaporator, and the dispersion medium was evaporated. Next, this was vacuum dried at 120°C for 24 hours to obtain particle powder. On a glass plate, 2 or 3 drops of a standard refractive solution with a known refractive index were added dropwise, and the powder was mixed therewith. This operation was performed using various standard refractive solutions, and the refractive index of the standard refractive solution when the mixed solution became transparent was taken as the refractive index of the particles.

(7) Content of metallic elements, alkali metals, and alkaline earth metals

Content of metal elements (Si, Al, Sn, Sb, Ti, Zr, Zn, Cu, Fe and In) in the particles and impurity elements such as Pd, Ag, Mn, Co, Mo, Ni, Cr, U, Th, The content of alkali metal and alkaline earth metal was measured as follows. That is, the particles were dissolved in hydrofluoric acid, heated to remove the hydrofluoric acid, and then pure water was added as needed. The obtained solution was measured using an ICP inductively coupled plasma emission spectrometry mass spectrometer (ICPM-8500 manufactured by Shimadzu Corporation) to measure the content of metal elements and impurity elements in the particles. Additionally, regarding the metal elements other than the impurity elements mentioned above, the total amount of metal elements other than carbon contained in the particles was calculated to be 100 parts by mass based on oxide.

(8) Specific surface area (A1) by pulse NMR

Using pulse NMR (AcornArea manufactured by Xigo nanotools), the relaxation time was measured for each dispersion liquid and dispersion medium. Then, the specific surface area (A1) was obtained from the above-mentioned equations (2) and (3). Regarding the measurement conditions, the magnetic field was set to 0.3 T, the measurement frequency was set to 13 MHz, the measurement nucleus was set to ¹ H NMR, and the CPMG pulse sequence method was used as the measurement method. Then, the sample volume was set to 1 ml, the Ka value was set to 0.000129, and the temperature was set to 25°C for measurement. Here, the value of Ka was calculated by performing pulse NMR measurement on a methanol dispersion of surface-treated particles and a methanol dispersion medium at a solid content concentration of 20% by mass and 25°C, and the values calculated by the above-mentioned equations (4) to (6) were used. .

(9) Porosity and density of particles

In the same manner as the average (D) of the primary particle diameters of the particles described above, the area of the cavity portion of the particles was determined from the TEM photograph. The equivalent circle diameter was calculated from the area, and the average value of the equivalent circle diameter was taken as the average of the cavity diameters. Assuming that the shape of the particles and cavities was a sphere, the average volume of the primary particles and the average volume of the cavities were obtained. Additionally, porosity was calculated as the ratio of the average volume of voids to the average volume of primary particles. Additionally, the density (Sd) of the particles was determined from the obtained porosity, the ratio of constituent components in the particles, and their densities.

(10) Specific surface area (A2)

Using the average (D) of the primary particle diameters of the particles, the specific surface area (A2) was determined by the following equation (4).

A2=6000/Sd/D … Equation (4)

(In the formula, Sd represents the density of particles (g/cm3).)

(11) Solid content of organosilicon compounds having functional groups

The dispersion was centrifuged for 30 minutes using a small ultracentrifuge (CS150GXL manufactured by Hitachi Koki Co., Ltd.) under the conditions of a temperature of 10°C and a rotation speed of 1,370,000 rpm (1,000,000 G). The precipitate of the obtained treatment liquid was collected and dried under vacuum at 120°C for 24 hours to obtain particle powder. For this powder, the amount of mass loss before and after heating to 500°C was measured using a thermogravimetric differential thermal analysis device (TG/DTA EXSTAR6000 MSD manufactured by Hitachi High-Tech Science Co., Ltd.), and from the difference from the original particle weight, organic silicon The amount of silicon derived from the compound was determined. Next, this amount of silicon was converted into the amount of solid content (R _n -SiO _(4-n)/2 ) derived from the organosilicon compound based on the structure of the organosilicon compound used for surface treatment. In this way, the solid content of the organosilicon compound having a functional group was determined.

<Preparation of coating solution for forming anti-reflective film>

The dispersion medium of the prepared methanol dispersion of particles (R1) was replaced with methyl isobutyl ketone (MIBK) in an evaporator, and a MIBK dispersion of particles (R1) with a solid content concentration of 20.5% by mass was prepared.

8.05 g of MIBK dispersion of these particles (R1), 1.07 g of multifunctional acrylate resin (Light Acrylate DPE-6A, manufactured by Kyoesha Chemical Co., Ltd.), and bifunctional acrylate resin (Tomoe Kogyo Co., Ltd.) 0.12 g of reactive silicone oil for water repellent fires (KF-2012, manufactured by Shin-Etsu Chemical Co., Ltd.), 0.05 g of silicone-modified polyurethane acrylate (Cico UT-, manufactured by Mitsubishi Chemical Co., Ltd.) 4314, solid content concentration 30 mass%) by mixing 0.37 g, 0.09 g photopolymerization initiator (Omnirad TPO H manufactured by IGM RESINS B.V.), 64.65 g isopropyl alcohol, 9.60 g MIBK, and 16.00 g isopropyl glycol. A 3.0% by mass coating liquid for forming an antireflection film was prepared.

<Manufacture of substrate with coating>

Hard coat paint (ELCOM HP-1004 manufactured by Nikki Shokubai Kasei Co., Ltd.) was applied to TAC film (FT-PB40UL-M manufactured by Fuji Film Co., Ltd., thickness 40㎛, refractive index 1.51) using the bar coater method (#18). It was applied, dried at 80°C for 120 seconds, and then cured by irradiating ultraviolet rays of 300mJ/cm2. In this way, a base material with a hard coat film was manufactured. The film thickness of the hard coat film was 8 μm. This hard coat film was commonly used in all examples and comparative examples.

Next, the coating liquid for forming an anti-reflection film was applied onto this hard coat film by the bar coater method (#4), dried at 80°C for 120 seconds, and then cured by irradiating ultraviolet rays of 600 mJ/cm2 in an N ₂ atmosphere. I ordered it. In this way, a base material provided with a transparent anti-reflection film was manufactured.

The following items on the substrate provided with the film were measured. The measurement results are shown in Table 6 (the same applies to the examples and comparative examples below).

(12) Film thickness of hard coat film

The film thickness of the hard coat film was measured at five arbitrary locations on the film using a digital gauge (gauge stand ST-0230 and digital gauge counter DG-5100 manufactured by Onosoki Co., Ltd.). The average value of five measured values was taken as the film thickness of the hard coat film.

(13) Thickness and reflectivity of transparent anti-reflection film

The film thickness of the film and reflectance at a wavelength of 550 nm were measured with an ellipsometer (EMS-1 manufactured by ULVAC). The measured reflectance was classified and evaluated as follows.

Evaluation standard:

0.7% or less : AA

More than 0.7% but less than 1.0% : A

More than 1.0% but less than 1.5% : B

More than 1.5% but less than 2.0% :C

greater than 2.0% :D

(14) Haze and total light transmittance

The haze and total light transmittance of the coated substrate were measured using a haze meter (NDH-5000 manufactured by Nippon Denshoku Kogyo Co., Ltd.).

(15) Measurement of scratch resistance

#0000 steel wool was used and the surface of the film was rolled 50 times while changing the load. At each load, the surface of the film was observed with the naked eye, and the load at which striped scratches were observed on the surface of the film was measured. The measurement results were classified as follows and the strength (scratch resistance) was evaluated.

Evaluation standard:

More than 1200g/㎠ :A

More than 800g/㎠ Less than 1200g/㎠ : B

More than 500g/㎠ Less than 800g/㎠ :C

Less than 500g/㎠ :D

(16) Pencil hardness

Pencil hardness was measured using a pencil hardness tester according to JIS K 5400. That is, the pencil is set at an angle of 45 degrees to the surface of the film, a predetermined load is applied to pull the pencil at a constant speed, the presence or absence of scratches on the surface of the film is observed, and scratches are confirmed on the surface of the film. Hardness was measured. The measurement results were classified as follows and hardness was evaluated.

Evaluation standard:

4H or more :A

3H : B

2H :C

H and below :D

(17) Comprehensive evaluation of reflectance, intensity and hardness

For evaluation of reflectance, scratch resistance, and pencil hardness, scores were assigned as follows.

AA: 5 points

A: 4 points

B: 3 points

C: 2 points

D: 1 point

Using these scores, a total score was calculated using the formula below, and the total score was classified into three levels to make a comprehensive judgment.

Total score calculation formula: (reflectance score) × (pencil hardness score) × (scratch resistance score)

In the comprehensive judgment, the following “A” or “B” was considered passing.

36 and above :A

16 or more but less than 36 : B

less than 16 :D

(18) Adhesion

On the surface of the base material provided with the film, 11 parallel scratches were made with a knife at intervals of 1 mm in length and width to create 100 squares. A cellophane tape was attached to this surface. Next, the cellophane tape was peeled off, and the number of cells in which the film remained without peeling was counted. These were classified as follows and adhesion was evaluated.

Evaluation standard :

Number of spaces remaining: 100 : B

Number of spaces remaining: 99 or less: D

[Example 2]

In Example 1, after the second step, the first step and the second step were performed sequentially again to prepare a methanol dispersion of the particles (R2) of this embodiment (number of repetitions of the first step and the second step = 2) episode).

A base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

[Example 3]

The same procedure as in Example 2 was carried out except that 0.8 g of γ-methacryloxypropyltrimethoxysilane (2 parts by mass as solid content (R _n -SiX _4-n ) relative to 100 parts by mass of particles (P1)) was used. A methanol dispersion of the particles of the embodiment (R3) was prepared.

A base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

[Example 4]

20 g of γ-methacryloxypropyltrimethoxysilane (50 parts by mass as solid content (R _{n -Si} A methanol dispersion of the particles (R4) of this embodiment was prepared in the same manner as in Example 1 except that it was repeated five times in order.

A base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

[Example 5]

In the second step, a methanol dispersion of particles (R5) of this embodiment was prepared in the same manner as in Example 1, except that 600 g of methanol (corresponding to 3 times the amount of methanol dispersion of particles (S1)) was used.

A base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

[Example 6]

In the second step, a methanol dispersion of particles (R6) of this embodiment was prepared in the same manner as in Example 1, except that 400 g of methanol (equivalent to twice the amount of methanol dispersion of particles (S1)) was used.

In the same manner as in Example 1 except that this dispersion was used, a substrate with a coating liquid and a coating was prepared, and each characteristic was evaluated.

[Example 7]

After adding 119880 g of pure water to 120 g of an aqueous dispersion of silica particles (USB-120 manufactured by Nikki Shokubai Kasei Co., Ltd., average particle diameter 25 nm, solid content concentration 20 mass %, Al ₂ O ₃ content in solid content 27 mass %), An aqueous solution of sodium hydroxide with a concentration of 1% by mass was added, and the pH was adjusted to 11.0. Thereafter, the obtained solution was heated to 98°C, and 22.4 kg of an aqueous sodium silicate solution with a concentration of 1.5% by mass as SiO ₂ and 22.4 kg of an aqueous solution of sodium aluminate with a concentration of 0.5% by mass as Al ₂ O ₃ were added to the solution. did. Afterwards, the dispersion of complex oxide particles (a7) was obtained by washing by centrifugal sedimentation. The average particle diameter of this composite oxide particle (a7) was 74 nm.

The dispersion of this composite oxide particle (a7) was heated to 98°C, and 60.0 kg of an aqueous sodium silicate solution with a SiO ₂ concentration of 1.5 mass% and 20.0 kg of an aqueous sodium aluminate solution with an Al ₂ O ₃ concentration of 0.5 mass% were added. , was added to the dispersion. Afterwards, washing was performed using an ultrafiltration membrane, so that the solid content concentration of the dispersion was 13% by mass. Thereafter, the dispersion was filtered through a capsule filter with an eye size of 1 μm, thereby obtaining a dispersion of composite oxide particles (b7). The average particle diameter of this composite oxide particle (b7) was 98 nm.

A methanol dispersion of the particles (R7) of this embodiment was prepared in the same manner as in Example 2, except that the dispersion of the composite oxide particles (b7) was used instead of the dispersion of the composite oxide particles (b1).

The methanol dispersion of particles (R7) was subjected to solvent substitution for MIBK in the same manner as in Example 1. After that, 4.88 g of MIBK dispersion of these particles (R7), 1.23 g of multifunctional acrylate resin (Light Acrylate DPE-6A manufactured by Kyoesha Chemical Co., Ltd.), and bifunctional acrylate resin (Tomoe Kogyo) 0.14 g of SR-238F, manufactured by Co., Ltd., 0.04 g of reactive silicone oil for water-repelling fires (KF-2012, manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.04 g of silicone-modified polyurethane acrylate (manufactured by Mitsubishi Chemical Co., Ltd.) By mixing 0.31 g of Cico UT-4314 (solid content concentration 30 mass%), 0.09 g of photopolymerization initiator (Omnirad TPO H manufactured by IGM RESINS B.V.), 65.19 g of isopropyl alcohol, 12.12 g of MIBK, and 16.00 g of isopropyl glycol. , a coating liquid with a solid content concentration of 2.5% by mass was prepared. A base material with a coating film was manufactured in the same manner as in Example 1 except that this coating liquid was used.

[Example 8]

After adding 117.0 kg of pure water to 3000 g of an aqueous dispersion of silica particles (USB-120 manufactured by Nikki Shokubai Kasei Co., Ltd.), an aqueous sodium hydroxide solution with a concentration of 1% by mass was added, and the pH was adjusted to 11.0. Afterwards, the obtained solution was heated to 98°C, and 11.6 kg of an aqueous sodium silicate solution with a SiO ₂ concentration of 1.5 mass% and 11.6 kg of an aqueous sodium aluminate solution with an Al ₂ O ₃ concentration of 0.5 mass% were added to the solution. did. Afterwards, the dispersion of complex oxide particles (a8) was obtained by washing by centrifugal sedimentation. The average particle diameter of this composite oxide particle (a8) was 27 nm.

The dispersion of this composite oxide particle (a8) was heated to 98°C, and 48.9 kg of an aqueous sodium silicate solution with a SiO ₂ concentration of 1.5 mass% and 16.3 kg of an aqueous sodium aluminate solution with an Al ₂ O ₃ concentration of 0.5 mass% were added. , was added to the dispersion. Afterwards, washing was performed using an ultrafiltration membrane, so that the solid content concentration of the dispersion was 13% by mass. Thereafter, the dispersion was filtered through a capsule filter with an eye size of 1 μm, thereby obtaining a dispersion of composite oxide particles (b8). The average particle diameter of this composite oxide particle (b8) was 41 nm.

A methanol dispersion of the particles (R8) of this embodiment was prepared in the same manner as in Example 2, except that the dispersion of the composite oxide particles (b8) was used instead of the dispersion of the composite oxide particles (b1).

Next, a base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

[Example 9]

After adding 29,250 g of pure water to 750 g of an aqueous dispersion of silica particles (USB-120, manufactured by Nikki Shokubai Kasei Co., Ltd.), an aqueous sodium hydroxide solution with a concentration of 1% by mass was added, and the pH was adjusted to 11.0. Thereafter, the obtained solution was heated to 98°C, and 5.83 kg of an aqueous sodium silicate solution with a SiO ₂ concentration of 1.5 mass% and 5.83 kg of an aqueous sodium aluminate solution with an Al ₂ O ₃ concentration of 0.5 mass% were added to the solution. did. Afterwards, the dispersion of complex oxide particles (a9) was obtained by washing by centrifugal sedimentation. The average particle diameter of this composite oxide particle (a9) was 225 nm.

The dispersion of this composite oxide particle (a9) was heated to 98°C, and 2.21 kg of an aqueous sodium silicate solution with a SiO ₂ concentration of 1.5 mass% and 0.74 kg of an aqueous sodium aluminate solution with an Al ₂ O ₃ concentration of 0.5 mass% were added. , was added to the dispersion. After that, washing was performed using an ultrafiltration membrane to set the solid content concentration to 13% by mass. Thereafter, the dispersion was filtered through a capsule filter with an eye size of 1 μm, thereby obtaining a dispersion of composite oxide particles (b9). The average particle diameter of this composite oxide particle (b9) was 242 nm.

To 500 g of the dispersion of the composite oxide particles (b9), 1125 g of pure water was added, and concentrated hydrochloric acid (concentration 35.5% by mass) was added dropwise, and the pH was adjusted to 1.0. To this dispersion, 10 L of a pH 3 hydrochloric acid aqueous solution and 5 L of pure water were added, and the aluminum salt dissolved in the dispersion was separated and washed using an ultrafiltration membrane. As a result, silica-based particles (c9) with a concentration of 5% by mass were obtained.

Next, aqueous ammonia was added to 500 g of the dispersion of silica-based particles (c9), the pH of the dispersion was adjusted to 10.5, and the dispersion was transferred to a pressure-resistant container. Next, the dispersion was heated to 200°C and held for 10 hours, then cooled to room temperature. Thereafter, the dispersion was subjected to ion exchange for 3 hours using 400 g of a cation exchange resin (Dia Ion SK1B manufactured by Mitsubishi Chemical Corporation), followed by an anion exchange resin (Diamond manufactured by Mitsubishi Chemical Corporation). Ion exchange was performed for 3 hours using 200 g of ion SA20A). Afterwards, using 200 g of cation exchange resin (Diaion SK1B manufactured by Mitsubishi Chemical Corporation), the dispersion was subjected to ion exchange at 80°C for 3 hours and washed to form an “outer shell containing silicon.” and particles having cavities inside them (original particles)” (P9) was obtained.

A methanol dispersion of particles (R9) of this embodiment was prepared in the same manner as in Example 2, except that this particle (P9) was used instead of the dispersion of particles (P1). The solid content concentration of this dispersion was 20% by mass.

The methanol dispersion of particles (R9) was subjected to solvent substitution with MIBK in the same manner as in Example 1. Thereafter, 3.22 g of the MIBK dispersion of these particles (R9), 1.09 g of a multifunctional acrylate resin (Light Acrylate DPE-6A manufactured by Kyoesha Chemical Co., Ltd.), and a bifunctional acrylate resin (Tomoe Kogyo Co., Ltd. 0.12 g of SR-238F, manufactured by Co., Ltd., 0.03 g of reactive silicone oil for water-repelling fires (KF-2012, manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.03 g of silicone-modified polyurethane acrylate (manufactured by Mitsubishi Chemical Co., Ltd.) By mixing 0.27 g of Cico UT-4314 (solid content concentration 30% by mass), 0.09 g of photopolymerization initiator (Omnirad TPO H manufactured by IGM RESINS B.V.), 65.74 g of isopropyl alcohol, 13.44 g of MIBK, and 16.00 g of isopropyl glycol. , a coating liquid with a solid content concentration of 2.0% by mass was prepared. A base material with a coating film was manufactured in the same manner as in Example 1 except that this coating liquid was used, and each characteristic was evaluated.

[Example 10]

To 15.0 kg of an aqueous dispersion of silica particles (Cataloid SI-550 manufactured by Nikki Shokubai Kasei Co., Ltd., average particle diameter 5 nm, SiO ₂ concentration 20 mass %), 85.0 kg of pure water was added, followed by hydroxide with a concentration of 1 mass %. Sodium aqueous solution was added to adjust the pH to 10.0. Thereafter, the obtained solution was heated to 80°C, and 6845 g of an aqueous sodium silicate solution with a concentration of 1.5% by mass as SiO ₂ and 6845 g of an aqueous sodium aluminate solution with a concentration of 0.5% by mass as Al ₂ O ₃ were added to the solution. Afterwards, the dispersion of complex oxide particles (a10) was obtained by washing by centrifugal sedimentation. The average particle diameter of this composite oxide particle (a10) was 19 nm.

The dispersion of this composite oxide particle (a10) was heated to 85°C, and 70.5 kg of an aqueous sodium silicate solution with a SiO ₂ concentration of 1.5 mass% and 23.5 kg of an aqueous sodium aluminate solution with an Al ₂ O ₃ concentration of 0.5 mass% were added to the mixture. , was added to the dispersion. Afterwards, the solid content concentration of the dispersion was adjusted to 13% by mass by washing using an ultrafiltration membrane. Thereafter, the dispersion was filtered through a capsule filter with an eye size of 1 μm, thereby obtaining a dispersion of composite oxide particles (b10). The average particle diameter of this composite oxide particle (b10) was 29 nm.

To 5000 g of the dispersion of the composite oxide particles (b10), 11250 g of pure water was added, and concentrated hydrochloric acid (concentration 35.5% by mass) was added dropwise to adjust the pH to 1.0. To this dispersion, 10 L of a pH 3 hydrochloric acid aqueous solution and 5 L of pure water were added, and the aluminum salt dissolved in the dispersion was separated and washed using an ultrafiltration membrane. As a result, silica-based particles (c10) with a concentration of 10% by mass were obtained.

Next, aqueous ammonia was added to 500 g of the dispersion of silica-based particles (c5), the pH of the dispersion was adjusted to 10.5, and the dispersion was transferred to a pressure-resistant container. Next, the dispersion was heated to 100°C and held for 10 hours, then cooled to room temperature. Thereafter, the dispersion was subjected to ion exchange for 3 hours using 800 g of a cation exchange resin (Dia Ion SK1B manufactured by Mitsubishi Chemical Corporation), followed by an anion exchange resin (Diamond manufactured by Mitsubishi Chemical Corporation). Ion exchange was performed for 3 hours using 400 g of ion SA20A). Afterwards, using 400 g of cation exchange resin (Diaion SK1B manufactured by Mitsubishi Chemical Corporation), the dispersion was subjected to ion exchange at 80°C for 3 hours and washed, thereby forming an “outer shell containing silicon.” and particles having cavities inside them (original particles)” (P10) was obtained.

A base material with a coating liquid and a coating film was manufactured in the same manner as in Example 1, except that an aqueous dispersion of the particles (P10) was used.

[Example 11]

To 5000 g of the dispersion of complex oxide particles (b1), 11250 g of pure water was added, and concentrated hydrochloric acid (concentration 35.5% by mass) was added dropwise, and the pH was adjusted to 3.0. To this dispersion, 5 L of a pH 3 hydrochloric acid aqueous solution and 5 L of pure water were added, and the aluminum salt dissolved in the dispersion was separated and washed using an ultrafiltration membrane. As a result, particles (c11) with a concentration of 10% by mass were obtained. A methanol dispersion of the particles (R11) of this embodiment was prepared in the same manner as in Example 2 except that this particle (c11) was used.

A base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

[Example 12]

In the first step, as the organosilicon compound, γ-methacryloxyoctyltrimethoxysilane (KBM-5803 manufactured by Shin-Etsu Chemical Co., Ltd.) was used in the same manner as in Example 2, in this embodiment. A methanol dispersion of particles (R12) was prepared.

A base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

[Comparative Example 1]

In the first step, as an organosilicon compound, 0.2 g of γ-methacryloxypropyltrimethoxysilane (0.5 parts by mass as solid content (R _n -SiX _4-n ) with respect to 100 parts by mass of particles (P1)) A methanol dispersion of surface-treated particles (RR1) was prepared in the same manner as in Example 1 except for what was used. In addition, in terms of process, these surface-treated particles (RR1) correspond to the particles (R1) of this embodiment obtained in Example 1 (the same applies to the comparative example particles (RR numbers) below).

A base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

[Comparative Example 2]

Without performing the second step, moisture and ammonia were removed from the dispersion of the surface-treated particles (S1) obtained in the first step using a molecular sieve (3A 1/16 manufactured by Kanto Chemical Co., Ltd.), and the solid content was reduced. The concentration was adjusted to 20% by mass. Except this, a methanol dispersion of surface-treated particles (RR2) was prepared in the same manner as in Example 1.

A base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

[Comparative Example 3]

In the second step, a methanol dispersion of surface-treated particles (RR3) was prepared in the same manner as in Example 1, except that 200 g of methanol (equivalent to 1 time the methanol dispersion of particles (S1)) was used.

A base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

[Comparative Example 4]

A methanol dispersion of surface-treated particles (RR4) was prepared in the same manner as in Example 10, except that the first and second steps were sequentially repeated five times.

A base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

[Comparative Example 5]

Using tetraethoxysilane (TEOS) as a silica source and referring to a known method (for example, the method described in Japanese Patent Application Laid-Open No. 2008-247664 or Patent Document 3), a core containing polystyrene particles was prepared. After producing the shell particles, the solvent was removed in a rotary evaporator, and then the polystyrene was removed by baking at 500°C for 2 hours. After that, the particles were dispersed in methanol, and a methanol dispersion of "particles having an outer shell containing silicon and a cavity inside the particle (original particle)" (RP5) was produced. A methanol dispersion of particles (RR5) was prepared in the same manner as in Example 1, except that this particle (RP5) was used and the first and second steps were not performed. The solid content concentration of this dispersion was 20% by mass.

A base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

[Comparative Example 6]

In Example 1, an aqueous sodium hydroxide solution was added to 500 g of the dispersion of silica-based particles (c1), the pH of the dispersion was adjusted to 10.6, and the dispersion was transferred to a pressure vessel. Next, the dispersion was heated to 200°C and held for 10 hours, then cooled to room temperature. Thereafter, the dispersion was subjected to ion exchange for 3 hours using 40 g of a cation exchange resin (Dia Ion SK1B manufactured by Mitsubishi Chemical Corporation), followed by an anion exchange resin (Dia Ion manufactured by Mitsubishi Chemical Corporation). Ion exchange was performed for 3 hours using 20 g of SA20A). Afterwards, the dispersion was further washed using 20 g of cation exchange resin (Diaion SK1B manufactured by Mitsubishi Chemical Corporation) and subjected to ion exchange at 80°C for 3 hours to form an “outer shell containing silicon.” and particles having cavities inside them (original particles)” (RP6) was obtained. A methanol dispersion of surface-treated particles (RR6) was prepared in the same manner as in Example 1, except that an aqueous dispersion of the particles (RP6) was used. The solid content concentration of this dispersion was 20% by mass.

A base material provided with a coating liquid and a coating film was manufactured in the same manner as in Example 1 except that this dispersion liquid was used.

Claims (9)

It is a dispersion of particles having an outer shell containing functional groups and silicon and a cavity inside the shell,
The average primary particle diameter (D) obtained by image analysis of the particles is 20 to 250 nm,
The carbon content of the particles is 0.5 to 10% by mass,
The amount of the organosilicon compound in the liquid excluding the particles from the dispersion is 0.50 parts by mass or less as a solid content with respect to 100 parts by mass of the particles,
dispersion. The dispersion according to claim 1, wherein the functional group contains at least one selected from an acryloyl group, a (meth)acryloyl group, and an epoxy group. The dispersion according to claim 1, wherein the particles have a refractive index of 1.08 to 1.38. The dispersion liquid according to claim 1, wherein the particles contain 98 parts by mass or more of silicon as SiO ₂ when the total amount of metal elements other than the carbon constituting the particles is expressed as 100 parts by mass on an oxide basis. . The method of claim 1, wherein the particles are SiO ₂ , or,
An oxide containing at least one element selected from Si and Al, Sn, Sb, Ti, Zr, Zn, Cu, Fe and In.
A dispersion containing at least one side of. The specific surface area of the particles according to claim 1, wherein the specific surface area of the particles (A1) is determined from pulse NMR measurement of a methanol dispersion of the particles, and the average of primary particle diameters (D) is obtained by image analysis of the particles. A dispersion wherein the ratio (A1/A2) of (A2) is 0.80 or less. A first step of surface-treating the particles by adding an organic silicon compound represented by the following formula (1) to a dispersion liquid containing particles having an outer shell containing silicon and a cavity inside the particle,
A second step is sequentially provided to remove unreacted organosilicon compounds from the dispersion of particles after surface treatment obtained in the first step,
The average primary particle diameter (D) obtained by image analysis of the particles is 20 to 250 nm,
The carbon content of the particles is 0.5 to 10% by mass,
The amount of the unreacted organosilicon compound in the liquid excluding the particles from the dispersion is 0.50 parts by mass or less as a solid content with respect to 100 parts by mass of the particles,
A method for producing a dispersion of particles having an outer shell containing a functional group and silicon and an inner cavity.
R _n -SiX _4-n (1)
(Wherein, R is an unsubstituted or substituted hydrocarbon group having 1 to 10 carbon atoms, ) The method according to claim 7, wherein the particles in the dispersion obtained in the second step contain 1.0 to 30 parts by mass of an organic silicon compound having a functional group as a solid content relative to 100 parts by mass of the particles before surface treatment in the first step. , Method for producing dispersions. The method for producing a dispersion according to claim 7, wherein after the second step, the first step and the second step are sequentially performed again.