Particles having a silicon-containing outer shell and a cavity inside, and a method for manufacturing the same.

Abstract

By reducing the size of the hollow portion of the particle and lowering the refractive index of the outer shell, the invention provides particles in which the decrease in transparency and increase in haze due to light scattering are suppressed. [Solution] These particles have a silicon-containing outer shell and a cavity inside. The average particle diameter determined by image analysis of these particles is 10-35 nm. The refractive index of these particles is 1.15-1.38. Furthermore, the average diameter of the cavity is 4-29 nm. In addition, the haze of a particle dispersion with a solid content of 20% by mass, in which the particles are dispersed in a monomer with a refractive index of 1.52, is 50% or less.

Description

[Technical Field]

[0001] The present invention relates to particles having a silicon-containing outer shell and a cavity inside, and a method for producing the same. [Background technology]

[0002] In recent years, there has been a surge in the development of display devices such as diffractive optical elements (DOEs) for XR / cross-reality (a general term for VR / virtual reality, AR / augmented reality, and MR / mixed reality) devices. DOEs are extremely small structures used in optical devices that change the phase of light propagating through optical structures. Materials for DOEs are required to have high transmittance and high or low refractive index, and the use of nanoparticles is being explored to enhance their functionality. Examples of materials for high refractive index include titania and zirconia particles, while examples of materials for low refractive index include magnesium fluoride and hollow particles.

[0003] To date, methods for lowering the refractive index of a composition have been known, such as using hollow silica particles or low refractive index particles with porous interiors in the coating solution. For example, Japanese Patent Publication No. 2019-119848 (Patent Document 1) and Japanese Patent Publication No. 2020-166156 (Patent Document 2) show that silica particles containing gas within the particles are used as a photosensitive resin composition to lower the refractive index of the film. However, in the case of optical waveguide type DOEs for XR glasses, the optical path length as an optical waveguide is long, which makes it easy for incident light to be lost due to light scattering. As a result, transparency decreases and haze occurs when incident light is irradiated, leading to a decrease in brightness as an XR glass. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-119848 [Patent Document 2] Japanese Patent Publication No. 2020-166156 [Overview of the project]

Problems to be Solved by the Invention

[0005] In recent years, for the multilayer structuring of resist films such as DOE, a combination of a high refractive index layer and a low refractive index layer is used. Here, the low refractive index layer is required to have high transparency and high smoothness. As a means of obtaining this low refractive index layer, for example, it is possible to blend hollow particles with a high porosity, that is, hollow particles with a large particle diameter. However, when blending hollow particles with a large particle diameter, there are problems such as a decrease in transparency due to light scattering and an increase in haze, resulting in a decrease in luminance and image quality. This problem becomes more prominent when the film thickness of the coating is on the order of μm. In order to reduce this problem, if the output of the light source is increased, the startup time of the battery will be shortened. Furthermore, in order to solve this (lengthen the battery startup time), the weight of the battery is inevitably increased.

[0006] By the way, Rayleigh scattering, which is light scattering in nanoparticles, becomes larger as the particle diameter becomes larger and as the refractive index difference between the particle and the resin becomes larger. Particularly in the case of hollow particles, since the refractive index difference between the outer shell of the particle and the cavity is larger than the refractive index difference between the outer shell of the particle and the resin, the influence of the average diameter of the cavity becomes larger. On the other hand, when blending hollow particles with a small particle diameter and a small average diameter of the cavity, since the porosity of the hollow particles is low and the refractive index is high, the decrease in the refractive index of the film becomes insufficient. Therefore, it is necessary to suppress the decrease in transparency due to light scattering and the increase in haze by making the cavity of the hollow particles smaller and lowering the refractive index of the outer shell.

Means for Solving the Problems

[0007] In order to solve such problems, the following particles were found. These particles have an outer shell containing silicon and a cavity inside. The average particle diameter of these particles by image analysis is 10 to 35 nm. Also, the refractive index of these particles is 1.15 to 1.38. Furthermore, the average diameter of the cavity is 4 to 29 nm. In addition, the haze of a particle dispersion liquid with a solid content concentration of 20% by mass dispersed in a monomer with a refractive index of 1.52 is 50% or less.

[0008] Hereinafter, this "particle having a silicon-containing outer shell and a cavity inside" may simply be referred to as "particle" or "the particle of the present invention."

[0009] These particles have a small particle size and a small average diameter of the cavity, a low refractive index, and low haze when dispersed in a monomer. A coating solution containing such particles yields a coating and structure with low light scattering and high transparency.

[0010] To obtain these particles, we discovered the following manufacturing method.

[0011] First, an alkaline aqueous solution containing amphoteric elements is prepared (first step). Next, a solution of a silicon-containing compound and an aqueous solution of an alkali-soluble inorganic element compound other than silicon are simultaneously added to this alkaline aqueous solution to create a dispersion of composite oxide particles a with an average particle size of 5 to 29 nm (second step). In this second step, the molar ratio (MOx / SiO2) of these added solutions is set to 0.1 to 2.0, where silicon oxide is represented as SiO2 and the oxides of inorganic elements other than silicon are represented as MOx.

[0012] Next, to the dispersion of composite oxide particles a obtained in the second step, a solution of a silicon-containing compound and an alkali-soluble aqueous solution of an inorganic element compound other than silicon are simultaneously added to prepare a dispersion of composite oxide particles b with an average particle size of 6 to 33 nm (third step). In this third step, the molar ratio (MOx / SiO2) of these added solutions is smaller than that of the second step, where silicon oxide is represented as SiO2 and the oxide of the inorganic element is represented as MOx.

[0013] Next, to the dispersion of composite oxide particles b obtained in the third step, a solution of a silicon-containing compound and an alkali-soluble aqueous solution of an inorganic element compound other than silicon are simultaneously added to prepare a dispersion of composite oxide particles c with an average particle size of 10 to 35 nm (fourth step). In this fourth step, the molar ratio (MOx / SiO2) of these added solutions is smaller than that in the third step, when silicon oxide is represented as SiO2 and the oxides of inorganic elements other than silicon are represented as MOx.

[0014] Next, an acid is added to the dispersion of composite oxide particles c obtained in the fourth step to remove at least some of the elements other than silicon that make up the composite oxide particles c, thereby preparing a dispersion of silica particles d (fifth step).

[0015] Next, the dispersion of silica particles d obtained in the fifth step is heated to 40-180°C at a heating rate of 3.0°C / min or less (sixth step).

[0016] The properties of the particles in the dispersion obtained in this sixth step are the same as those of the particles described above. [Effects of the Invention]

[0017] According to the particles of the present invention, coatings and structures with low light scattering and high transparency can be obtained. [Modes for carrying out the invention]

[0018] [particle] The particles according to the present invention will be described below.

[0019] The particles have a silicon-containing outer shell and a cavity inside. Image analysis of these particles shows an average particle diameter of 10-35 nm. The refractive index of these particles is 1.15-1.38. Furthermore, the average diameter of the cavity is 4-29 nm. In addition, the haze of a particle dispersion with a solid content of 20% by mass, in which the particles are dispersed in a monomer with a refractive index of 1.52, is 50% or less.

[0020] The average particle diameter, as determined by image analysis of the particles, is 10–35 nm. This is the average value obtained by taking images at a predetermined magnification using a transmission electron microscope (TEM), processing the image of any 300 particles to determine the particle area, and then calculating the equivalent diameter of a circle from that area. When the average particle diameter is within this range, light scattering is suppressed, transparency is high, and the particles can exist in the dispersion without settling. Furthermore, they have good dispersibility in coatings, films, and structures, and light scattering when irradiated with incident light is small, resulting in highly transparent coatings and structures.

[0021] In this case, particles with an average particle diameter of less than 10 nm have a small proportion of voids (porosity), and their refractive index does not become sufficiently low, so the desired low refractive index effect cannot be obtained. Conversely, if the particle diameter exceeds 35 nm, light scattering is likely to occur when incident light is irradiated, and the surface irregularities of the coating film become large, which may prevent the acquisition of a transparent coating or structure. The average particle diameter is preferably 12 to 32 nm, more preferably 15 to 30 nm, and even more preferably 15 to 25 nm.

[0022] The refractive index of the particles is 1.15 to 1.38. When the refractive index of the particles is within this range, a transparent, low refractive index coating and structure can be obtained. Here, it is difficult to obtain particles with a refractive index of less than 1.15. Conversely, if it exceeds 1.38, the low refractive index effect may be insufficient. The refractive index is preferably 1.15 to 1.36, more preferably 1.15 to 1.32, and even more preferably 1.15 to 1.28.

[0023] The average diameter of the particle cavity is 4 to 29 nm. When the average diameter of the cavity is within this range, light scattering during incident light irradiation is small, resulting in highly transparent coatings and structures.

[0024] In this case, particles with an average diameter of less than 4 nm have a small proportion of voids (porosity) and their refractive index does not become sufficiently low, thus failing to achieve the desired low refractive index effect. Conversely, if the diameter exceeds 29 nm, light scattering is likely to occur when incident light is irradiated, which may prevent the acquisition of a transparent coating or structure. The average diameter of this void is preferably 7 to 27 nm, more preferably 10 to 25 nm.

[0025] The porosity of the particles is preferably 5 to 60%. However, it is not particularly limited as long as the aforementioned refractive index is satisfied. If it is less than 5%, the refractive index will not be sufficiently low, and the refractive index reduction effect will be insufficient. Conversely, if it exceeds 60%, light scattering will increase, and there is a risk that a transparent coating or structure cannot be obtained. The proportion of cavities in these particles is more preferably 10 to 55%, and even more preferably 20 to 50%.

[0026] The haze of a dispersion obtained by dispersing particles in a monomer with a refractive index of 1.52 so that the solid content concentration is 20% by mass is 50% or less. When the haze of the dispersion is within this range, light scattering during incident light irradiation is small, resulting in a highly transparent coating and structure.

[0027] Here, if the haze exceeds 50%, light scattering during incident light irradiation increases. Therefore, coatings and structures using these particles are prone to light scattering during incident light irradiation, which may reduce transparency. There is no specific lower limit set for the haze, but for example, it is 0.0%. This haze is preferably 40% or less, more preferably 30% or less, and particularly preferably 20% or less.

[0028] Particle Rayleigh ratio (R Θ The Rayleigh ratio is calculated by the following formula (1). This Rayleigh ratio is 8.0 × 10⁻⁶. 5 The following is preferable. When the Rayleigh ratio is within this range, light scattering during incident light irradiation is small, resulting in a highly transparent coating and structure.

[0029]

number

[0030] In the formula, n1 represents the particle refractive index, n2 represents the solvent refractive index (= 1.52), and d represents the average particle diameter (nm) by image analysis.

[0031] Here, when the Rayleigh ratio (R Θ ) exceeds 8.0×10 5 , the light scattering during incident light irradiation increases. Therefore, a film or structure using these particles is likely to cause light scattering during incident light irradiation, and there is a risk of reduced transparency. Although no particular lower limit value is set for the Rayleigh ratio, for example, it is 0.0. This Rayleigh ratio is more preferably 3.0×10 5 or less, and even more preferably 8.0×10 4 or less.

[0032] The product of the Rayleigh ratio (R θ ) of the particles and the number of particles per unit volume (N) (R Θ ×N) is obtained by the following formula (2). This product is preferably 4.0×10 10 or less. When this product is within this range, the light scattering during incident light irradiation is small, and thus a highly transparent film and structure can be obtained.

[0033]

Equation

[0034] In the formula, n1 represents the particle refractive index, n2 represents the solvent refractive index (= 1.52), d represents the average particle diameter by image analysis (nm), and N represents the number of particles per unit volume (= 1000 (nm) × 1000 (nm) × 1000 (nm) ÷ particle volume (nm 3 / particle) is represented.

[0035] Here, the product of the Rayleigh ratio (R Θ ) and the number of particles per unit volume (N) is 4.0×10 10When this value exceeds a certain threshold, light scattering during incident light irradiation increases. Therefore, coatings and structures using these particles are prone to light scattering during incident light irradiation, resulting in reduced transparency. There is no specific lower limit set for this product, but for example, it is 0.0. This product is more preferably 1.5 × 10 10 More preferably 7.0 × 10 9 The following applies:

[0036] The refractive index of the outer shell of the particle (n s The refractive index (n) of this outer shell can be calculated by the following equation (3). s The refractive index (n) is preferably 1.42 or less. s When the refractive index of the cavity shown in equation (3) is within this range, the difference in refractive index between the outer shell and the resin becomes small. As a result, light scattering during incident light irradiation is reduced, and a highly transparent coating and structure can be obtained. c The refractive index (RF) varies depending on the state of the cavity. For example, if the cavity is filled with gas, the refractive index will be 1.00. If the cavity is filled with liquid, the refractive index will be that of the liquid.

[0037]

number

[0038] In the formula, d is the average particle diameter determined by image analysis, d c n is the average value of the diameter of the particle cavity. p The particle refractive index is n c This represents the refractive index of the particle cavity.

[0039] Here, the refractive index of the outer shell of the particle (n s If the refractive index (n) exceeds 1.42, there is a risk that light scattering during incident light irradiation will increase. Therefore, coatings and structures using these particles are prone to light scattering during incident light irradiation, which may reduce transparency. s The lower limit of the refractive index (n) is not specifically set, but for example it is 1.34. s ) is more preferably 1.40 or less, even more preferably 1.38 or less, and particularly preferably 1.36 or less.

[0040] Image analysis of the particles indicates that the proportion (number ratio) of particles with a diameter of 45 nm or larger is preferably 10% or less. When the proportion of particles with a diameter of 45 nm or larger is within this range, light scattering during incident light irradiation is small, resulting in a highly transparent coating and structure.

[0041] Here, if the proportion of particles with a diameter of 45 nm or larger exceeds 10%, light scattering during incident light irradiation and surface irregularities of the coating become greater. Therefore, coatings and structures using these particles are prone to light scattering during incident light irradiation, which may reduce transparency. The proportion of particles with a diameter of 45 nm or larger is more preferably 5% or less, even more preferably 1% or less, and most preferably 0%.

[0042] The coefficient of variation of particle size is preferably 40% or less. When the coefficient of variation of particle size is within this range, light scattering during incident light irradiation is small, resulting in a highly transparent coating and structure.

[0043] Here, if the coefficient of variation of particle size exceeds 40%, there is a possibility that light scattering during incident light irradiation will increase. Therefore, coatings and structures using these particles are prone to light scattering during incident light irradiation, which may reduce transparency. The coefficient of variation is more preferably 30% or less, and even more preferably 20% or less.

[0044] The carbon content of the particles is preferably 0.1 to 5.0% by mass. When the carbon content is within this range, the particles can exist in the dispersion without settling. Furthermore, such particles can exist in high dispersion in coating solutions, films, or structures, resulting in highly transparent films and structures. Moreover, when such particles are used in a resist film, their high compatibility with alkaline developers allows for the creation of a resist film with excellent developability.

[0045] Here, particles with a carbon content of less than 0.1% by mass may have difficulty achieving sufficient dispersibility and stability in dispersions, coatings, or films and structures, potentially leading to reduced transparency. Furthermore, if such particles are used in a resist film, insufficient bonding with the resin may occur, making pattern formation difficult. Conversely, exceeding 5.0% by mass does not further improve dispersibility, stability, transparency, or developability. Rather, it may increase the refractive index or lead to excessive bonding with the resin, making development difficult. The carbon content is more preferably 0.5 to 4.5% by mass, and even more preferably 1.0 to 4.0% by mass.

[0046] The silica, a component of the particles, is created using a "silicon-containing compound." Examples of this "silicon-containing compound" include at least one selected from silicates, acidic silicic acid solutions, and organosilicon compounds. In some cases, the particles of the present invention may be surface-treated using an organosilicon compound. In such cases, the carbon content varies depending on the structure and amount of the surface-treated organosilicon compound. This carbon content preferably originates from functional groups contained in the particle shell.

[0047] Here, for example, if the raw material used to produce the "original particles" before surface treatment with the organosilicon compound is not an organosilicon compound, but rather the organosilicon compound of formula (4) described later is used as a surface treatment agent for the original particles, the aforementioned preferred carbon content of 0.1 to 5.0% by mass is the amount of the organosilicon compound in solid content (R) per 100 parts by mass of the original particles. n -SiO (4-n) / 2 This amounts to approximately 0.2 to 12.5 parts by mass contained in the surface-treated particles. Incidentally, examples of organosilicon compound raw materials for producing the "original particles" include alkoxysilanes such as tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), and phenyltrimethoxysilane.

[0048] Here, if the amount of organosilicon compound contained in the surface-treated particles is less than 0.2 parts by mass per 100 parts by mass of the original particles, it becomes difficult to obtain sufficient dispersibility and stability in the dispersion, coating solution, or structure, and transparency may decrease. Furthermore, if such particles are used in a resist film, the bonding with the resin may be insufficient, making pattern formation difficult. Conversely, even if the amount of the organosilicon compound exceeds 12.5 parts by mass, dispersibility, stability, and developability will not improve further. Rather, the refractive index may increase, or excessive bonding with the resin may make development difficult. The amount of surface treatment is more preferably 0.6 to 11.0 parts by mass, and even more preferably 1.0 to 10.0 parts by mass. Incidentally, if the "original particles" are made from organosilicon compounds as raw materials, the "original particles" contain carbon, so in order to obtain the target carbon content of the particles of the present invention, the amount of solid content of the organosilicon compound introduced as a surface treatment agent to the particles will be less than when surface-treated "original particles that do not contain carbon," depending on the carbon content of the "original particles."

[0049] Particle 29 In Si-NMR analysis, it is preferable that the ratio of the peak area representing the Q4 structure of silicon atoms, which appears with a chemical shift of -108 to -120 ppm, to the sum of the peak areas representing each of the Q1 to Q4 structures of silicon atoms, which appear with a chemical shift of -78 to -120 ppm, is less than 85%. Within this range, light scattering during incident light irradiation is small, resulting in a highly transparent coating and structure. Furthermore, when such particles are used in a resist film, the high silanol group content and high compatibility with alkaline developers result in a resist film with excellent developability.

[0050] In addition, 29 In Si-NMR spectroscopy, the Q1 structure is represented by a peak appearing at chemical shifts of -78 to -88 ppm, the Q2 structure by a peak appearing at chemical shifts of -88 to -98 ppm, and the Q3 structure by a peak appearing at chemical shifts of -98 to -108 ppm.

[0051] The peaks assigned to Q1 represent Si atoms with one (-OSi) group and three (-OH) groups bonded to them, the peaks assigned to Q2 represent Si atoms with two (-OSi) groups and two (-OH) groups bonded to them, the peaks assigned to Q3 represent Si atoms with three (-OSi) groups and one (-OH) group bonded to them, and the peaks assigned to Q4 represent Si atoms with four (-OSi) groups bonded to them.

[0052] Here, if the area ratio of the peak representing the Q4 structure is 85% or more, there is a risk that light scattering during incident light irradiation will increase. As a result, coatings and structures using these particles may have reduced transparency. Furthermore, when such particles are used in a resist film, the low number of silanol groups may result in poor compatibility with alkaline developers, making pattern formation difficult. It is more preferable that the area ratio of the peak representing the Q4 structure is less than 80%.

[0053] The particles preferably contain functional groups. In particular, the inclusion of functional groups in the particle shell enhances the dispersibility of the particles in dispersions, coatings, or films and structures. Films and structures using these particles exhibit suppressed particle aggregation and high transparency. Furthermore, the inclusion of silicon in the particle shell results in particles with a low refractive index, and the presence of silicon-derived surface OH groups facilitates the introduction of the aforementioned functional groups.

[0054] Examples of functional groups included in the particle shell include at least one selected from alkyl groups, acryloyl groups, (meth)acryloyl groups, vinyl groups, alkoxy groups, mercapto groups, epoxy groups, glycidoxy groups, amino groups, phenyl groups, and phenylamino groups. Among these, alkyl groups, acryloyl groups, (meth)acryloyl groups, vinyl groups, mercapto groups, and epoxy groups are preferred because they have high polymerization ability. These functional groups can be identified by measuring and analyzing the dried powder of the particles using a Fourier transform infrared spectrometer (FT-IR).

[0055] These functional groups are preferably derived from an organosilicon compound represented by the following formula (4). This organosilicon compound can be used, for example, as a raw material used to produce the aforementioned "original particles," as a surface treatment agent used to treat the surface of the particles, or both. Incidentally, particles treated with such a surface treatment agent are preferable because they have many functional groups on their outer shell surface, resulting in high dispersibility in dispersions, coatings, or films and structures, and highly transparent films and structures can be obtained.

[0056] R n -SiX 4-n (4) In the formula, R is an unsubstituted or substituted hydrocarbon group having 1 to 10 carbon atoms, X is an alkoxy group, hydroxyl group, or hydrogen atom having 1 to 4 carbon atoms, and n is an integer from 0 to 3.

[0057] As mentioned above, the amount of organosilicon compounds containing these functional groups is, in proportion to 100 parts by mass of the particles before surface treatment (original particles), the amount of solids (R n -SiO (4-n) / 2 The amount is preferably 0.2 to 12.5 parts by mass. When such particles are used in coatings or structures, they exhibit high dispersibility within the coating or structure, resulting in highly transparent coatings or structures.

[0058] The silicon content in the particles is preferably 98 parts by mass or more as silica (SiO2) when the total amount of metal elements other than carbon constituting the particles is expressed as oxides in 100 parts by mass. If the SiO2 content is 98 parts by mass or more, it is easier to obtain coatings and structures with a low refractive index and high transparency. This SiO2 content is more preferably 99 parts by mass or more, even more preferably 99.5 parts by mass or more, and particularly preferably 100 parts by mass.

[0059] Thus, the constituent elements of the particles preferably include silicon (Si) as the main element. Here, the constituent elements of the particles may be any of the following (a) to (c). These elements are derived from materials preferably used in the production of the particles.

[0060] (a) SiO2 (b) An oxide containing Si and at least one element selected from Al, Sn, Sb, Ti, Zr, Zn, Cu, Fe, and In. Note that the oxides containing these elements may be mixtures or composite oxides. (c) A mixture of (a) and (b) above.

[0061] By the way, the content of elements other than Si in the particles as described in item (b) above is preferably less than 2 parts by mass on an oxide basis, when the total amount of metal elements other than carbon constituting the particles is expressed as 100 parts by mass on an oxide basis. If this content is 2 parts by mass or more, there is a risk that the refractive index will increase or that a transparent coating or structure cannot be obtained due to light scattering. This content is more preferably less than 1 part by mass, even more preferably less than 0.5 parts by mass, and most preferably 0 parts by mass.

[0062] Furthermore, as long as the refractive index does not deviate from the refractive index range of the particles described above, particles other than those listed in (a) to (c) above, such as "particles having an outer shell and a cavity inside" or so-called "solid particles" that do not have a cavity inside, may also be present. The proportion of these particles other than the particles of the present invention also changes depending on the type and composition ratio of the elements that make up the particles. For example, in the case of "solid particles" that, like the particles of the present invention, contain 98 parts by mass or more of silicon as SiO2 and have a similar average particle diameter, the number ratio of solid particles to the total number of particles is preferably less than 10%. This ratio can be determined, for example, by counting the number of particles of the present invention and solid particles in a predetermined field of view of a TEM photograph. If this ratio is 10% or more, the refractive index may be higher than the desired range. In the case of such solid particles, the number ratio is more preferably less than 5%, even more preferably less than 2%, particularly preferably less than 1%, and most preferably 0%. If particles of different elemental species are present, for example, the ratio of particles of the present invention to other particles can be determined by mapping the particles in a predetermined field of view using energy-dispersive X-ray spectroscopy (EDS) and counting the number of particles of the present invention and particles of other elemental species.

[0063] The content of each element belonging to alkali metals and alkaline earth metals, which are impurities in the particles, is preferably 500 ppm or less relative to the particle when expressed as an oxide. When these elements are present in low amounts, particle adhesion is reduced, resulting in high stability and uniform dispersion in dispersions, coatings, or films and structures, thus yielding films and structures with high transparency.

[0064] Here, if the content is greater than 500 ppm, the proportion of particles adhering to each other increases, which may result in insufficient stability of the dispersion or coating solution, or inability to obtain a transparent film or structure. The content is more preferably 100 ppm or less. Alkali metals refer to Li, Na, K, Rb, Cs, and Fr, while alkaline earth metals refer to Be, Mg, Ca, Sr, Ba, and Ra.

[0065] Furthermore, it is preferable that the content of each impurity in the particles, Ag, Cr, Cu, Mn, Mo, Ni, and Pd, be less than 100 ppm, and the content of each of U and Th be less than 0.3 ppb. If the content of these elements is high, the dispersion may become discolored, or it may not be possible to obtain a coating or structure with the desired refractive index. Moreover, when the particles are used in semiconductor circuits such as highly integrated logic and memory, or in optical sensors, where high purity is required, it is preferable that the content of each of the aforementioned elements, including Ag, Cr, Cu, Mn, Mo, Ni, and Pd, as well as Al, As, B, Bi, Cd, Co, Fe, Ga, Ge, In, Pb, Sb, Sn, Ti, V, Zn, and Zr, be less than 0.1 ppm. If the content of these elements is 0.1 ppm or higher, the metallic elements may cause insulation failure in the circuit, short circuits, or a decrease in light transmittance. This can lead to a decrease in the dielectric constant of the insulating film, an increase in the impedance of the metal wiring, a delay in response speed, and an increase in power consumption. In particular, in the case of U and Th, they generate radioactivity, and even in trace amounts, their presence can cause semiconductor malfunctions due to radioactivity, which is undesirable.

[0066] To obtain particles with low content of such elements, it is preferable to use materials that do not contain these elements and have high chemical resistance for the equipment used to manufacture the particles. Specifically, plastics such as FRP and carbon fiber, and alkali-free glass are preferred. Furthermore, it is preferable to purify the raw materials used by distillation, ion exchange, and filtration.

[0067] As mentioned above, methods for obtaining high-purity particles include preparing raw materials with low levels of these elements in advance, and minimizing contamination from the particle manufacturing equipment. In addition, it is possible to reduce these elements from particles manufactured without sufficient measures, such as through ion exchange.

[0068] The shape of the particles and the shape of the cavities are not particularly limited. Examples include spherical, ellipsoidal (rugby ball) shape, cocoon shape, konpeito (sugar candy) shape, chain shape, and cube shape. Among these, spherical particles are preferred because they have high dispersibility and can be uniformly dispersed in the coating or structure. Furthermore, the cavity inside the outer shell is preferably shaped to follow the shape of the particle's outer form. This is because, depending on the thickness of the outer shell, sufficient strength can be obtained when stress is applied to the particle by ensuring the outer shell has a uniform thickness. Moreover, it is preferable that the cavity is also spherical, similar in shape to the spherical particle.

[0069] The dispersion medium and concentration of the dispersion are not particularly limited, as long as the particles are stably dispersed in the liquid without aggregation or precipitation.

[0070] Examples of dispersion media include water, alcohols, esters, glycols, ethers, ketones, and aprotic polar solvents. These may be used individually or in combination of two or more.

[0071] The concentration of the dispersion is preferably such that the solid content concentration of the particles is 1 to 40% by mass. If the solid content concentration is less than 1% by mass, the processing time during the manufacture of the coating solution may be extended. Conversely, if it exceeds 40% by mass, 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.

[0072] [Method for producing a dispersion of particles] The particle manufacturing method according to the present invention comprises: a first step of preparing an alkaline aqueous solution containing an amphoteric element; a second step of simultaneously adding a "solution of a silicon-containing compound" and an "alkaline-soluble aqueous solution of an inorganic element compound other than silicon" to the alkaline aqueous solution prepared in the first step, such that the molar ratio (MOx / SiO2) is 0.1 to 2.0, where the silicon oxide is represented as SiO2 and the inorganic element oxide is represented as MOx, to produce a dispersion of composite oxide particles a having an average particle diameter of 5 to 29 nm; and adding the respective solutions of the "solution of a silicon-containing compound" and the "alkaline-soluble aqueous solution of an inorganic element compound other than silicon" to the dispersion of composite oxide particles a produced in the second step, such that the molar ratio is smaller than the molar ratio (MOx / SiO2) in the second step. In addition, the process includes, in order: a third step of preparing a dispersion of composite oxide particles b having an average particle diameter of 6 to 33 nm; a fourth step of adding solutions of a silicon-containing compound and an alkali-soluble aqueous solution of an inorganic element compound other than silicon to the dispersion of composite oxide particles b prepared in the third step, in a molar ratio smaller than the molar ratio (MOx / SiO2) in the third step, to prepare a dispersion of composite oxide particles c having an average particle diameter of 10 to 35 nm; a fifth step of adding acid to the dispersion of composite oxide particles c to remove at least some of the elements other than silicon that constitute the composite oxide particles c, to prepare a dispersion of silica particles d; and a sixth step of heating the dispersion of silica particles d at a heating rate of 3.0°C / min or less to a maximum temperature of 40 to 180°C. The particles of the present invention are obtained by this process.

[0073] The particles produced in this manner have small particle size and average cavity diameter, a low refractive index, and low haze when dispersed in a monomer. When such particles are used in coatings and structures, coatings and structures with low light scattering and high transparency can be obtained. Each step is described below.

[0074] [First step] First, an alkaline aqueous solution is prepared. Here, it is preferable that the alkaline aqueous solution contains an element that forms an amphoteric oxide. An element that forms an amphoteric oxide means that the oxide containing that element dissolves in an acid with a pH of 3 or less, and dissolves in an alkali with a pH of 10 or more. More specifically, it contains at least one element selected from Al, As, B, Bi, Cd, Co, Fe, Ga, Ge, In, Pb, Sb, Si, Sn, Ti, V, Zn, and Zr. Among these, Al is preferred because it readily reacts with silicon-containing compounds to form composite oxide particles. Similarly, Si (silicon) is preferred because it readily reacts with silicon-containing compounds. Examples of alkaline aqueous solutions containing these preferred elements include aqueous solutions of sodium aluminate, aluminum hydroxide, and sodium silicate.

[0075] The alkaline aqueous solution is not particularly limited as long as its pH is greater than 7.0. If amphoteric elements are dissolved and present, a pH of 10.0 or higher is preferred. More preferably, the pH is 10.5 or higher, even more preferably 11.0 or higher, and particularly preferably 11.0 to 13.0. Furthermore, this alkaline aqueous solution may contain particles containing the aforementioned "elements that form amphoteric oxides". The particles containing the "elements that form amphoteric oxides" in this alkaline aqueous solution preferably have an average particle diameter of 5 to 15 nm.

[0076] Here, if the average particle diameter of the particles is less than 5 nm, it is difficult to obtain the particles themselves. Conversely, if the average particle diameter exceeds 15 nm, the refractive index of the particles of the present invention obtained in the end may not be sufficiently low. This average particle diameter is more preferably 5 to 10 nm.

[0077] The oxide-equivalent concentration of the amphoteric oxide element in the alkaline aqueous solution is preferably less than 5.0% by mass. This concentration suppresses the aggregation of particles obtained in the second step. There is no particular lower limit set for this concentration, but from the viewpoint of stably obtaining particles with uniform particle size and high sphericity, for example, it is 0.1% by mass. This concentration is more preferably less than 4.0% by mass, and even more preferably less than 3.5% by mass.

[0078] [Second process] In this process, a dispersion of composite oxide particles a is prepared by simultaneously adding a "solution of a silicon-containing compound" and an "alkaline-soluble aqueous solution of an inorganic element compound other than silicon" to the "alkaline aqueous solution" prepared in the first process. For these added solutions, the molar ratio (MOx / SiO2) is set to 0.1 to 2.0, where silicon oxide is represented as SiO2 and oxides of inorganic elements other than silicon are represented as MOx.

[0079] Here, "silicon-containing compounds" can be defined as at least one selected from, for example, silicates, acidic silicic acid solutions, and organosilicon compounds.

[0080] The silicate is preferably one or more silicates selected from alkali metal silicates, ammonium silicates, and organic base silicates. Examples of alkali metal silicates include sodium silicate and potassium silicate. Examples of organic bases include quaternary ammonium salts such as tetraethylammonium salt, and amines such as monoethanolamine, diethanolamine, and triethanolamine. Ammonium silicates or organic base silicates also include alkaline solutions obtained by adding ammonia, quaternary ammonium hydroxide, amine compounds, etc., to a silica solution.

[0081] As the acidic silicic acid solution, a silicic acid solution obtained by removing alkali from an alkaline silicate aqueous solution by treating it with a cation exchange resin can be used, and an acidic silicic acid solution with a pH of 2 to 4 is particularly preferred.

[0082] The organosilicon compound used in this process is preferably one represented by formula (4) above, in which n is between 0 and 3.

[0083] Incidentally, in the organosilicon compounds of formula (4), compounds with n = 1 to 3 have poor hydrophilicity, so it is preferable to hydrolyze them beforehand so that they can be uniformly mixed in the reaction system. Well-known methods can be used for hydrolysis. When basic catalysts such as alkali metal hydroxides, aqueous ammonia, or amines are used as hydrolysis catalysts, these basic catalysts can be removed after hydrolysis to obtain an acidic solution for use. Also, when acidic catalysts such as organic acids or inorganic acids are used to prepare the hydrolysate, it is preferable to remove the acidic catalyst by ion exchange or the like after hydrolysis. Furthermore, it is preferable to use the obtained hydrolysate of the organosilicon compound in the form of an aqueous solution. Here, an aqueous solution means a state in which the hydrolysate is transparent and not in a cloudy gel state.

[0084] Examples of organosilicon compounds include those listed in Table 1 below, where n is 0 to 3. For example, TMOS, TEOS, 3-methacryloxypropyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyldimethoxysilane, 3-acryloxypropyltriethoxysilane, and 8-methacryloxyoctyltrimethoxysilane are preferred.

[0085] Furthermore, "alkali-soluble compounds of inorganic elements other than silicon" include alkali metal salts or alkaline earth metal salts, ammonium salts, and quaternary ammonium salts of metal or nonmetal oxoacids that constitute oxides of inorganic elements other than silicon. Specifically, these include sodium aluminate, sodium tetraborate, ammonium zirconyl carbonate, potassium antimonate, potassium stannate, sodium aluminosilicate, sodium molybdate, ammonium cerium nitrate, and sodium phosphate.

[0086] These "compounds containing silicon" and "compounds of inorganic elements other than silicon" have high solubility on the alkaline side. However, when the two are mixed in this pH range of high solubility, the solubility of silicate ions and oxoacid ions such as aluminate ions decreases, and these complexes precipitate to form colloidal particles.

[0087] The concentrations of the "silicon-containing compound" solution and the "alkali-soluble inorganic element compound other than silicon" aqueous solution are preferably 0.05 to 3.0 mass% as SiO2 and MOx, respectively. When the concentrations are within this range, particle adhesion is suppressed, and particles with high sphericity can be obtained.

[0088] Here, if the concentration of the "silicon-containing compound" solution and the concentration of the "alkali-soluble inorganic element compound other than silicon" aqueous solution are less than 0.05 mass% as SiO2 and MOx, respectively, the particle growth rate will be slow, and the production efficiency to satisfy the desired average particle size of composite oxide particles a may be low. Conversely, if the concentration exceeds 3.0 mass%, the particles may adhere to each other, resulting in irregular particle shapes or aggregation of particles.

[0089] In the addition of the solution in this process, the pH of the reaction system is preferably 10.0 or higher, and the temperature is preferably 50 to 98°C. When the pH and temperature are within this range, the composite oxide particles a can be efficiently grown by adding a "solution of a silicon-containing compound" and an "alkaline-soluble aqueous solution of an inorganic element compound other than silicon". The pH is more preferably 10.5 or higher, even more preferably 10.5 to 13.0, and particularly preferably 11.0 to 13.0. The temperature is more preferably 60 to 98°C, even more preferably 70 to 98°C, and particularly preferably 70 to 85°C.

[0090] Next, we will explain the molar ratio (MOx / SiO2).

[0091] When the aforementioned "alkali-soluble compounds of inorganic elements other than silicon" are expressed as "oxides," suitable examples include one or more of the following: Al2O3, As2O3, B2O3, Bi2O3, CdO, CoO, Fe2O3, Ga2O3, GeO2, In2O3, PbO, Sb2O3, SnO2, TiO2, VO, ZnO2, and ZrO2. Furthermore, examples of these "composite oxides of inorganic elements other than silicon" include zinc alumina oxide and indium tin oxide. These oxides are referred to as MOx, and their mole count is used in the calculation of the molar ratio. If multiple types of these oxides are present in the reaction system, the sum of the mole counts of each oxide is used. Also, when the aforementioned "compounds containing silicon" are expressed as SiO2, their mole count is used in the calculation of the molar ratio here.

[0092] Furthermore, the molar ratio calculation in the second step will be performed without including the "amphoteric oxide elements" used in the first step. Also, alkali metals and alkaline earth metals are treated as impurities rather than "elements constituting particles," and therefore will not be included in the above MOx calculation.

[0093] These points will be addressed similarly in the third step, which will be described later.

[0094] In the second step, the "solution of a silicon-containing compound" and the "alkali-soluble aqueous solution of an inorganic element compound other than silicon" are added simultaneously so that the molar ratio (MOx / SiO2) of these added solutions is between 0.1 and 2.0. When the molar ratio (MOx / SiO2) in the second step is within this range, the structure of the composite oxide particles mainly consists of silicon and other elements alternately bonded with oxygen in between. That is, oxygen atoms are bonded to the four bonding points of the silicon atom, and many structures are formed in which the non-silicon element M is bonded to these oxygen atoms. As a result, when removing the non-silicon element M in the fifth step, which will be described later, the silicon atoms can be removed as silicate monomers or oligomers along with element M without destroying the shape of the composite oxide particles.

[0095] If the molar ratio is less than 0.1, the proportion of "elements other than silicon" removed in the fifth step described later will be small, which may result in the porosity of the final particles not being sufficiently large. Conversely, if the molar ratio exceeds 2.0, particle growth may be suppressed, which may reduce the production efficiency until the desired average particle size of the composite oxide particles a is satisfied, or the particles may aggregate. This molar ratio is preferably 0.2 to 2.0, more preferably 0.3 to 2.0.

[0096] Thus, the composite oxide particles a obtained in the second step are removed by acid treatment in the fifth step described later, forming a cavity inside the outer shell of the final particles. For this reason, it is preferable that the composite oxide particles a are in a form that is easily removed by acid treatment.

[0097] The average particle size (Da) of the composite oxide particles a is approximately 5 to 29 nm.

[0098] Here, if the average particle diameter (Da) is less than 5 nm, the porosity of the particles will not be large enough, which may result in an insufficient reduction of the refractive index. Conversely, if it exceeds 29 nm, the light scattering of the final particles will increase, which may result in insufficient transparency and haze of the coating or structure. The average particle diameter (Da) is preferably 6 to 25 nm, more preferably 8 to 22 nm, and even more preferably 10 to 20 nm.

[0099] [Third step] In this step, a "solution of a silicon-containing compound" and an "alkali-soluble aqueous solution of an inorganic element compound other than silicon" are added to a dispersion of composite oxide particles a in a molar ratio (MOx / SiO2) smaller than the molar ratio (MOx / SiO2) of the solution added in the second step. This causes the composite oxide particles a to grow, producing a dispersion of composite oxide particles b. These composite oxide particles b are formed by the formation of a layer b around the composite oxide particles a, with a molar ratio (MOx / SiO2) smaller than that of composite oxide particles a. Since this layer b is less susceptible to acid than composite oxide particles a, it forms part of the outer shell of the final particles.

[0100] If the molar ratio (MOx / SiO2) in the second step is A and the molar ratio (MOx / SiO2) in the third step is B, it is preferable that the ratio (B / A) be less than 1.0. If the ratio (B / A) is less than 1.0, the silica component on the surface of the composite oxide particles increases, making it easier to form the outer shell. As a result, even if elements other than silicon are removed in the fifth step described later, the shape of the composite oxide particles will not be destroyed, and hollow silica particles can be obtained stably. If the ratio (B / A) is 1.0 or more, it is difficult to form an outer shell with a large silica component, so when elements other than silicon are removed in the fifth step, the composite oxide particles are destroyed, making it difficult to maintain the particle shape. For this reason, it may be difficult to obtain hollow silica particles. The ratio (B / A) is more preferably 0.8 or less, and even more preferably 0.6 or less.

[0101] These composite oxide particles b are fabricated so that their average particle size (Db) is between 6 and 33 nm.

[0102] Here, if the average particle diameter (Db) is less than 6 nm, the porosity of the particles will be small, and the refractive index reduction effect may be insufficient. Conversely, if it exceeds 33 nm, the light scattering of the final particles will be large, and the transparency and haze of the coating or structure may be insufficient. The average particle diameter (Db) is preferably 8 to 31 nm, more preferably 10 to 29 nm, and even more preferably 10 to 24 nm.

[0103] The "silicon-containing compounds" and "alkali-soluble inorganic element compounds other than silicon" used in the third step are selected from those exemplified in the second step. These compounds may be the same types as those used in the second step, or they may be different types exemplified in the second step.

[0104] The dispersion of composite oxide particles a used in this process preferably has a pH of 10.0 or higher.

[0105] The concentrations of the "silicon-containing compound" solution and the "alkali-soluble inorganic element compound other than silicon" aqueous solution are preferably 0.05 to 3.0% by mass, respectively, as SiO2 and MOx. When the concentrations are within this range, aggregation of the composite oxide particles b obtained in the third step is suppressed, and monodisperse particles can be obtained.

[0106] In the addition of the solution in this step, the pH of the reaction system is preferably 10.0 or higher, and the temperature is preferably 50 to 98°C. When the pH and temperature are within this range, the composite oxide particles b can grow efficiently by adding the "solution of a silicon-containing compound" and the "aqueous solution of an alkali-soluble inorganic element compound other than silicon". The pH is more preferably 10.5 or higher, even more preferably 10.5 to 13.0, and particularly preferably 11.0 to 13.0. The temperature is more preferably 60 to 98°C, even more preferably 70 to 98°C, and particularly preferably 70 to 85°C.

[0107] [Fourth step] In this step, a "solution of a silicon-containing compound" and an "alkaline-soluble aqueous solution of an inorganic element compound other than silicon" are added to a dispersion of composite oxide particles b in a molar ratio (MOx / SiO2) smaller than the molar ratio (MOx / SiO2) of the solution to be added in the third step. This causes the composite oxide particles b to grow and a dispersion of composite oxide particles c is produced.

[0108] If the molar ratio (MOx / SiO2) in the third step is B and the molar ratio (MOx / SiO2) in the fourth step is C, it is preferable that the ratio (C / B) be less than 1.0. If the ratio (C / B) is less than 1.0, the silica component on the surface of the composite oxide particles increases, making it easier to form the outer shell. As a result, even if elements other than silicon are removed in the fifth step described later, the shape of the composite oxide particles will not be destroyed, and hollow silica particles can be obtained stably. If the ratio (C / B) is 1.0 or higher, it is difficult to form an outer shell with a large silica component, so when elements other than silicon are removed in the fifth step, the composite oxide particles are destroyed, making it difficult to maintain the particle shape. For this reason, it may be difficult to obtain hollow silica particles. The ratio (C / B) is more preferably 0.8 or less, even more preferably 0.6 or less, and particularly preferably 0.4 or less.

[0109] These composite oxide particles c are fabricated so that their average particle size (Dc) is between 10 and 35 nm.

[0110] Here, if the average particle diameter (Dc) is less than 10 nm, the porosity of the particles becomes small, which may make it difficult to obtain coatings or structures with a low refractive index. Conversely, if it exceeds 35 nm, the light scattering of the particles increases, which may result in insufficient transparency and haze in the coatings or structures. The average particle diameter (Dc) is preferably 12 to 32 nm, more preferably 15 to 30 nm, and even more preferably 15 to 25 nm.

[0111] Furthermore, the value (dc) obtained by subtracting the average particle diameter of composite oxide particle a from the average particle diameter of composite oxide particle c and dividing the result by 2 is preferably between 3 and 10 nm. When the value (dc) is within this range, the shape as a hollow particle is easily maintained, and the particle has a low refractive index.

[0112] Here, if the value (dc) is less than 3 nm, the resulting outer shell may become too thin, making it difficult to maintain the particle shape. Conversely, if the value (dc) exceeds 10 nm, the particle porosity may become too small, making it difficult to obtain a low refractive index coating or structure. This value (dc) is more preferably 3 to 8 nm, even more preferably 3 to 6 nm, and particularly preferably 3 to 5 nm.

[0113] These composite oxide particles c are formed by a layer c surrounding composite oxide particles b, with a molar ratio (MOx / SiO2) smaller than that of composite oxide particles b. Because this layer c is less susceptible to acid than composite oxide particles b, it forms part of the outer shell of the final particle. Furthermore, because this layer c has a higher density than layer b, although the details have not been confirmed, it is hypothesized that it forms a density gradient in the outer shell structure of the final particle. As a result, light scattering is suppressed, and a highly transparent coating and structure can be obtained.

[0114] The "silicon-containing compound" and the "alkali-soluble inorganic element compound other than silicon" used in the fourth step are selected from those exemplified in the second step. These compounds may be the same type as those used in the second step, or they may be different types exemplified in the second step.

[0115] The dispersion of composite oxide particles b used in this process preferably has a pH of 10.0 or higher.

[0116] The concentrations of the "silicon-containing compound" solution and the "alkali-soluble inorganic element compound other than silicon" aqueous solution are preferably 0.05 to 3.0 mass% as SiO2 and MOx, respectively. When the concentrations are within this range, aggregation of the composite oxide particles c obtained in the fourth step is suppressed, and monodisperse particles can be obtained.

[0117] In the addition of the solution in this process, the pH of the reaction system is preferably 10.0 or higher, and the temperature is preferably 50 to 98°C. When the pH and temperature are within this range, the composite oxide particles c can grow efficiently by adding a "solution of a silicon-containing compound" and an "aqueous solution of an alkali-soluble inorganic element compound other than silicon". The pH is more preferably 10.5 or higher, even more preferably 10.5 to 13.0, and particularly preferably 11.0 to 13.0. The temperature is more preferably 60 to 98°C, even more preferably 70 to 98°C, and particularly preferably 70 to 85°C.

[0118] [Fifth step] In this process, an acid is added to a dispersion of composite oxide particles c to remove at least some of the elements other than silicon that make up the composite oxide particles c, thereby preparing a dispersion of silica particles d. Elemental removal is achieved, for example, by dissolving them using mineral or organic acids, by ion exchange removal through contact with a cation exchange resin, or by a combination of these methods.

[0119] The concentration of the dispersion of composite oxide particles c varies depending on the processing temperature, but it is preferably 0.1 to 30% by mass when the composite oxide particles c are converted to oxide.

[0120] Here, if the concentration is less than 0.1 mass%, the amount of silica dissolved will be large, which may make it difficult to maintain the shape of the composite oxide particles. Also, the low concentration will result in low processing efficiency. Conversely, if the concentration is higher than 30 mass%, the dispersion of particles may be insufficient. Furthermore, in composite oxide particles with a high content of elements other than silicon, it may be difficult to remove the elements other than silicon uniformly or efficiently. The concentration of the dispersion of composite oxide particles c is more preferably 0.5 to 25 mass%.

[0121] The removal of the above elements is preferably carried out until the molar ratio (MOx / SiO2) of the resulting silica particles d is 0.03 or less.

[0122] If the molar ratio (MOx / SiO2) is greater than 0.03, it may become difficult to obtain a structure with a high refractive index, sufficient strength to maintain the particle shape, and high transparency in the final particles. The molar ratio (MOx / SiO2) is more preferably 0.01 or less.

[0123] A dispersion of silica particles d, from which at least some elements other than silicon have been removed, can be washed by known washing methods such as ultrafiltration as needed. Washing removes at least some of the dissolved elements other than silicon. In this case, if some alkali metal ions and other elements in the dispersion are removed beforehand and then ultrafiltration is performed, a dispersion of silica particles d with high dispersion stability can be obtained.

[0124] Furthermore, this dispersion, from which at least some elements other than silicon have been removed, can also have some of the dissolved elements other than silicon, or alkali metal ions, removed by contacting it with at least one of a cation exchange resin and an anion exchange resin. When washing, heating the solution can be used to make the washing process more effective.

[0125] By washing in this manner, the amount of impurities such as alkali metals in the final particles can be effectively reduced.

[0126] [Sixth step] In this process, the dispersion of silica particles d obtained in the fifth step is heated to 40-180°C at a heating rate of 3.0°C / min or less. This allows the particles to be densified while maintaining their hollow particle shape.

[0127] If the heating rate is faster than 3.0°C / min, the silicon content on the particle surface will dissolve rapidly, causing the hollow particle shape to collapse and making it difficult to obtain low refractive index particles. There is no specific lower limit set for the heating rate, but for example, it is 0.3°C / min. If the heating rate is extremely slow, it will take too long to reach the target temperature, which may reduce production efficiency. The heating rate is preferably 0.5 to 2.8°C / min, more preferably 0.8 to 2.5°C / min.

[0128] Furthermore, if the heating temperature is below 40°C, the precipitation of silicon in the particles may be insufficient, and the hollow particle shape may not be fixed. Conversely, if the temperature exceeds 180°C, the precipitation of silicon in the particles may be excessive, which may cause the hollow shape to collapse due to the reduction of the outer shell, or the densification of the outer shell may be insufficient. After heating to the target temperature, it is acceptable to cool the material, but it is preferable to maintain that temperature for 30 minutes or more in order to ensure stable production. The heating temperature is preferably 60 to 160°C, more preferably 80 to 140°C.

[0129] In this process, the concentration of the silica particle d dispersion is preferably 0.1 to 30% by mass in terms of silica.

[0130] If the concentration is less than 0.1% by mass, the particles may dissolve excessively, and it may not be possible to obtain particles with internal cavities. Also, the low concentration will result in low processing efficiency. Conversely, if the concentration is higher than 30% by mass, the particles may aggregate. The concentration of the dispersion of silica particles d is more preferably 0.5 to 25% by mass.

[0131] [Particle surface treatment] The particles obtained in the sixth step may be surface-treated by adding an organosilicon compound. It is preferable to use organosilicon compounds with n of 0 to 3 as shown in formula (4) above. When using an organosilicon compound with n of 0, it is preferable to use a partially hydrolyzed product of the organosilicon compound. This is preferable because the introduction of a functional group improves dispersibility in the coating solution and film, and the structure has high transparency. This organosilicon compound may be used alone or in combination.

[0132] The surface treatment method for particles involves first preparing a dispersion of the particles. It is preferable to use alcohols such as methanol or ethanol as the dispersion medium. A predetermined amount of the organosilicon compound represented by formula (4) is added to this dispersion, and the organosilicon compound is hydrolyzed. Water may be added to this hydrolysis as needed. The ratio (Mw / Mo) of moles of water (Mw) to moles of the organosilicon compound (Mo) used is preferably 1 or greater.

[0133] If the ratio (Mw / Mo) is less than 1, hydrolysis may be insufficient, potentially resulting in poor transparency of the coating or structure, as well as insufficient haze. While there is no specific upper limit set for this ratio, if it exceeds 500, the hydrolysis reaction becomes vigorous, and the organosilicon compounds may polymerize, making efficient treatment of the particle surface with organosilicon compounds difficult. This ratio is more preferably between 1 and 100.

[0134] Furthermore, in this hydrolysis, an acid or alkali may be used as a hydrolysis catalyst if necessary. Ammonia is preferred among these. This is because, when ammonia is used, any residual ammonia in the dispersion is easily removed, and the stability of the dispersion is easily maintained. (M) N ) and the ratio (M) of the number of moles (Mo) of organosilicon compounds. N The value of / Mo) is preferably between 0.05 and 50.

[0135] Here, the ratio (M N If the ratio ( / Mo) is less than 0.05, hydrolysis may be insufficient, potentially resulting in insufficient transparency of the coating or structure, as well as poor haze. If this ratio exceeds 50, the hydrolysis reaction becomes more vigorous, potentially leading to polymerization of organosilicon compounds and making efficient treatment of the particle surface with organosilicon compounds difficult. This ratio is more preferably 0.1 to 10.

[0136] The surface treatment is preferably carried out in a homogeneous system, and to promote the reaction between the particles and the organosilicon compound, it is preferable to heat the dispersion medium at a temperature below its boiling point (e.g., room temperature to 120°C) for 0.5 to 48 hours.

[0137] This surface treatment results in particles whose surfaces are chemically bonded to organosilicon compounds. When used in coatings or structures, these particles exhibit high dispersibility in the coating solution or structure, yielding highly transparent coatings and structures.

[0138] Examples of organosilicon compounds include those shown in Table 1. These organosilicon compounds may be present individually in the particles, or in combination of multiple types. In surface treatment, these organosilicon compounds can be treated individually, mixed, or even treated in stages, using the same type, a mixture of multiple types, or multiple types separately.

[0139] [Table 1]

[0140] The amount of this organosilicon compound is, relative to 100 parts by mass of particles before surface treatment, the amount of solids (R n -SiO (4-n) / 2 It is preferable to perform surface treatment so that the amount is 0.2 to 12.5 parts by mass.

[0141] Furthermore, the physical properties and preferred ranges of the particles ultimately obtained by this manufacturing method are the same as those described above.

[0142] [Coating liquid for film formation] The particles of the present invention can be applied to a coating solution for film formation. This coating solution comprises particles, a matrix-forming component, and a dispersion medium. This dispersion medium comprises at least one of water and an organic dispersion medium. In addition, it may contain additives such as polymerization initiators, leveling agents, and surfactants.

[0143] The particle concentration in the coating solution is preferably 5 to 95% by mass as solid content, relative to the total amount of solid content including particles and matrix-forming components. If the particle concentration is less than 5% by mass, it may be difficult to sufficiently reduce the refractive index of the coating. Conversely, if it is more than 95% by mass, cracks may occur in the coating, surface irregularities may increase, and transparency and haze may deteriorate. The particle concentration is more preferably 20 to 90% by mass, and even more preferably 35 to 85% by mass.

[0144] 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, UV-curable resins, thermosetting resins, and thermoplastic resins. Furthermore, if patterning is required, it is preferable to include alkali-soluble groups.

[0145] Examples of UV-curable resins include (meth)acrylic resins, γ-glycyloxy resins, urethane resins, and vinyl resins.

[0146] Examples of thermosetting resins include urethane resins, melamine resins, silicon resins, butyral resins, reactive silicone resins, phenolic resins, epoxy resins, unsaturated polyester resins, and thermosetting acrylic resins.

[0147] Examples of thermoplastic resins include polyester resin, polycarbonate resin, polyamide resin, polyphenylene oxide resin, thermoplastic acrylic resin, vinyl chloride resin, fluororesin, vinyl acetate resin, and silicone rubber.

[0148] Examples of alkali-soluble groups include hydroxyl groups, phenolic hydroxyl groups, carboxyl groups, fluorinated alcohol groups, sulfonimide groups, bis(alkylcarbonyl)methylene groups, and alkylene oxide groups.

[0149] These resins may be copolymers or modified forms of two or more resins, or may be used in combination. Furthermore, these resins may be emulsion resins, water-soluble resins, or hydrophilic resins.

[0150] The components that form these resins are preferably monomers or oligomers because their particles are easily dispersed.

[0151] The concentration of the matrix-forming component in the coating solution is preferably 5 to 95% by mass as solid content, relative to the total amount of solid content including particles and matrix-forming components. If the concentration of the matrix-forming component is less than 5% by mass, film formation becomes difficult. Even if a film is obtained, there is a risk of cracking in the film, increased surface irregularities, and deterioration of transparency and haze. Conversely, if the concentration is greater than 95% by mass, the amount of particles is small, making it difficult to sufficiently reduce the refractive index. The concentration of the matrix-forming component is more preferably 10 to 80% by mass, and even more preferably 15 to 65% by mass.

[0152] As organic dispersion media, those that can uniformly disperse particles and dissolve or disperse additives such as matrix-forming components and polymerization initiators are used. Among these, hydrophilic dispersion media and polar dispersion media are preferred. As shown in Table 2, examples of hydrophilic dispersion media include alcohols, esters, glycols, and ethers. Examples of polar dispersion media include esters, ketones, and aprotic materials. These may be used individually or in mixtures of two or more.

[0153] [Table 2]

[0154] As additives, any additives that have been conventionally used for film formation can be used as desired. For example, polymerization initiators and leveling agents are used to promote polymerization of matrix-forming components and improve film-forming properties.

[0155] Examples of polymerization initiators include those shown in Table 3.

[0156] Examples of leveling agents include acrylic leveling agents, silicone leveling agents, fluorine leveling agents, nonionic leveling agents, cationic leveling agents, and anionic leveling agents. From the viewpoint of improving strength, leveling agents having a fluorine group are preferably used.

[0157] For convenience, the concentrations of these additives in the coating solution are counted as matrix-forming components if they are present as solids after film formation, and as matrix components after film formation.

[0158] [Table 3]

[0159] The solid content concentration of the coating solution (the ratio of the total solid content of particles and matrix-forming components to the coating solution) is preferably 0.1 to 60% by mass.

[0160] Here, if the solid content concentration of the coating solution is less than 0.1% by mass, the processing time during the manufacture of the coated substrate will be longer, which may reduce productivity and make it difficult to form a thick film. Conversely, if it is higher than 60% by mass, the stability of the coating solution may decrease. Also, the viscosity of the coating solution will increase, which may reduce the coatability. The solid content concentration of the coating solution is more preferably 1 to 50% by mass.

[0161] [Coated base material] A coating is formed on the substrate using the above-mentioned coating solution.

[0162] Specifically, the coating solution is applied to the substrate, followed by drying and UV irradiation to form a film on the substrate. The method of applying the coating solution is not particularly limited as long as it can form a film on the substrate. For example, well-known methods such as spraying, spinning, roll coating, bar coating, slit coater printing, gravure printing, and microgravure printing can be used. Drying is performed, for example, by heating to about 50-150°C to evaporate and remove the dispersion medium. After that, UV irradiation is performed to promote polymerization of the resin component and harden the film. The film is mainly formed of matrix (resin) components and particles.

[0163] In a coating, the ratio of particles to solid matrix components in the coating solution directly corresponds to the ratio of particle components to matrix in the coating. As mentioned above, any additives remaining as solids in the coating solution are counted as part of the matrix.

[0164] The film thickness can be appropriately selected depending on the application. For example, 100 nm to 10 μm is preferred for resist films and DOEs, while 50 to 250 nm is preferred for anti-reflective films.

[0165] The refractive index of the transparent coating is preferably 1.10 to 1.44. Here, it is difficult to obtain a transparent coating with a refractive index of less than 1.10, and if the refractive index exceeds 1.44, the desired effect obtained by lowering the refractive index cannot be obtained. The refractive index of the transparent coating is more preferably 1.10 to 1.41, even more preferably 1.10 to 1.38, and particularly preferably 1.10 to 1.35.

[0166] The light transmittance of the coated substrate is preferably 90.0% or higher. If the light transmittance is less than 90.0%, the image clarity in display devices and the like may be insufficient. More preferably, the light transmittance is 91.5% or higher, even more preferably 93.0% or higher, and particularly preferably 95.0% or higher.

[0167] Furthermore, the haze of the coated substrate is preferably 1.5% or less, more preferably 1.0% or less, even more preferably 0.5% or less, and particularly preferably 0.3% or less.

[0168] Furthermore, the surface irregularities of the coated substrate are preferably less than 2.5 nm.

[0169] Here, if the surface irregularities are 2.5 nm or greater, light scattering on the film surface will increase, potentially degrading transparency and haze. More preferably, these surface irregularities are less than 2.0 nm, even more preferably less than 1.5 nm, and particularly preferably less than 1.0 nm.

[0170] While known substrates can be used, from the viewpoint of transparency, examples of transparent resin substrates include glass, polycarbonate, acrylic resin, polyethylene terephthalate, triacetylcellulose (TAC), polymethyl methacrylate resin, and cycloolefin polymer.

[0171] Furthermore, a coated substrate with another coating formed on it can also be used. Examples of other coatings include conventionally known hard coat films, primer films, high refractive index films, conductive films, and the like.

[0172] The following describes embodiments of the present invention.

[0173] [Example 1] <Production of particle dispersions> A sodium aluminate aqueous solution with a concentration of 22% by mass as Al2O3 was added to pure water to prepare 10.0 kg of sodium aluminate aqueous solution with a concentration of 1.0% by mass as Al2O3 and a pH of 12.6 (first step).

[0174] Next, this was heated to 80°C, and 7.5 kg of a sodium silicate aqueous solution with a concentration of 1.5% by mass as SiO2 and 7.5 kg of a sodium aluminate aqueous solution with a concentration of 0.5% by mass as Al2O3 were added simultaneously. After that, washing was performed by centrifugal sedimentation to obtain a dispersion of composite oxide particles (a1). The average particle size of these composite oxide particles (a1) was 17 nm (second step).

[0175] The dispersion of composite oxide particles (a1) was heated to 80°C, and 20.8 kg of an aqueous sodium silicate solution with a concentration of 1.5% by mass as SiO2 and 11.0 kg of an aqueous sodium aluminate solution with a concentration of 0.5% by mass as Al2O3 were added simultaneously. Subsequently, the dispersion was washed using an ultrafiltration membrane to adjust the solid content concentration to 13% by mass. After that, washing was performed by centrifugal sedimentation to obtain a dispersion of composite oxide particles (b1). The average particle size of these composite oxide particles (b1) was 21 nm (third step).

[0176] The dispersion of composite oxide particles (b1) was heated to 80°C, and 32.0 kg of an aqueous sodium silicate solution with a concentration of 1.5% by mass as SiO2 and 5.05 kg of an aqueous sodium aluminate solution with a concentration of 0.5% by mass as Al2O3 were added simultaneously. Subsequently, the dispersion was washed using an ultrafiltration membrane to adjust the solid content concentration to 13% by mass. After that, washing was performed by centrifugal sedimentation to obtain a dispersion of composite oxide particles (c1). The average particle size of these composite oxide particles (c1) was 25 nm (fourth step).

[0177] 5000g of the dispersion of these composite oxide particles (c1) was mixed with 11250g of pure water, and concentrated hydrochloric acid (35.5% by mass) was added dropwise to adjust the pH to 1.0. To this, 10L of pH 3 hydrochloric acid aqueous solution and 5L of pure water were added, and the dissolved aluminum salt was separated using an ultrafiltration membrane. After washing, silica-based particles (d1) with a concentration of 10% by mass were obtained (fifth step).

[0178] Next, ammonia water was added to 500g of a dispersion of silica particles (d1) to adjust the pH of the dispersion to 10.5, and then it was transferred to a pressure vessel. Next, it was heated to 120°C at a heating rate of 2.0°C / min and held for 6 hours, and then cooled to 25°C (sixth step).

[0179] Subsequently, ion exchange was performed for 3 hours using 800g of cation exchange resin (Diaion SK1B, manufactured by Mitsubishi Chemical Corporation), followed by 3 hours of ion exchange using 400g of anion exchange resin (Diaion SA20A, manufactured by Mitsubishi Chemical Corporation). After that, washing was performed by ion exchange at 80°C for 3 hours using another 400g of cation exchange resin to obtain an aqueous dispersion of particles (P1).

[0180] An aqueous dispersion of these particles (P1) was subjected to ultrafiltration to replace the solvent with methanol, thereby producing a methanol dispersion of particles (P1) with a solid content concentration of 20% by mass.

[0181] <Surface treatment of particles using organosilicon compounds> To 200 g of a methanol dispersion of these particles (P1), 0.4 g of 28% by mass aqueous ammonia and 4.0 g of pure water were added, and the mixture was stirred at room temperature for 0.5 hours.

[0182] Next, as an organosilicon compound, 2.0 g of γ-methacryloxypropyltrimethoxysilane (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) (solid content (R) per 100 parts by mass of particles (P1) n -SiX 4-n 5 parts by mass of () were added and the mixture was stirred at 50°C for 24 hours to obtain a dispersion of surface-treated particles (S1).

[0183] Furthermore, the methanol dispersion of these particles (S1) was subjected to an evaporator to replace the dispersion medium with PGME, yielding a PGME dispersion of particles (S1) with a solid content concentration of 20.5% by mass. This was then used to manufacture a coating solution for forming a resist film, as described later.

[0184] The particles and their dispersions were measured using the following method.

[0185] Tables 4-6 show the characteristics of each manufacturing process for the particles, as well as the properties of the particles and dispersions (the same applies to the following examples and comparative examples).

[0186] (1) Average particle diameter of the particles The particle dispersion was diluted to 0.01% by mass and then dried on a collodion film in a copper cell for an electron microscope. Next, it was photographed at a predetermined magnification using a field emission transmission electron microscope (HF5000, Hitachi High-Technologies Corporation). For 300 arbitrary particles from the obtained TEM images, the particle area was determined from the image processing, and the equivalent circle diameter was calculated from that area. The average of these equivalent circle diameters was taken as the average particle diameter.

[0187] (2) Average diameter of the cavity in the particle, thickness of the outer shell, and porosity Similar to the average particle diameter described above, the area of ​​the cavity portion of the particle was determined from the TEM image, and the equivalent diameter of the circle was calculated from that area. The average of these equivalent diameters was taken as the average diameter of the cavity. The difference between the average particle diameter and the average diameter of the cavity was divided by 2 to calculate the thickness of the particle's outer shell. Furthermore, assuming that the shape of the particle and cavity is a perfect sphere, the average volume of the particle and the average volume of the cavity were determined, and the porosity was calculated as the ratio of the average volume of the cavity to the average volume of the particle.

[0188] (3) Refractive index The particle dispersion was placed in an evaporator and the dispersion medium was evaporated. Next, the mixture was vacuum-dried at 120°C for 24 hours to obtain particle powder. Two or three drops of a standard refractive index solution with a known refractive index were added to a glass substrate, and the powder was mixed with it. This operation was performed with various standard refractive index solutions, and the refractive index of the standard refractive index solution when the mixture became transparent was taken as the refractive index of the particles.

[0189] (4) Haze of a solution dispersed in a monomer resin with a refractive index of 1.52 A methanol dispersion of particles was prepared by replacing the dispersion medium with a monofunctional acrylate resin (Viscote #160 BZA, manufactured by Osaka Organic Chemical Industry Co., Ltd., refractive index 1.52) in an evaporator to create a monomer dispersion with a solid content concentration of 20% by mass. The obtained dispersion was placed in a 2 mm glass cell, and the haze of the dispersion was measured using a haze meter (COH-7700, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0190] (5) Rayleigh ratio (R Θ ) Using the refractive index of the particles, the refractive index of the solvent, and the average particle diameter, the Rayleigh ratio (R) of the particles can be calculated using the following formula (1). Θ ) was sought.

[0191]

number

[0192] (In the formula, n1 is the particle refractive index, n2 is the solvent refractive index (=1.52), and d is the average particle diameter (nm) determined by image analysis.)

[0193] (6) Rayleigh ratio (R Θ ) and the product of the number of particles per unit volume (N) (R Θ ×N) Using the average particle diameter of the particles, the particle volume (nm) 3 The number of particles per unit volume (R) was calculated by determining the number of particles per unit volume (=1000(nm) × 1000(nm) × 1000(nm)) and dividing the volume by the particle volume. The obtained number of particles per unit volume was compared with the aforementioned Rayleigh ratio (R) of the particle. Θ Using ), the product (R) of the number of particles per unit volume (N) is calculated. Θ We calculated ×N).

[0194]

number

[0195] (In the formula, n1 is the particle refractive index, n2 is the solvent refractive index (=1.52), d is the average particle diameter (nm) determined by image analysis, and N is the number of particles per unit volume (=1000(nm) × 1000(nm) × 1000(nm) ÷ particle volume (nm)) 3 (Represents / items).

[0196] (7) Refractive index of the outer shell Using the average particle diameter, the average diameter of the particle cavity, the refractive index of the particle, and the refractive index of the particle cavity, the refractive index of the outer shell (n) can be calculated from the following equation (3). s ) was sought.

[0197]

number

[0198] (In the formula, d is the average particle diameter determined by image analysis, d c n is the average value of the diameter of the particle cavity. p The particle refractive index is n c (This represents the refractive index of the particle cavity.)

[0199] (8) The number percentage of particles with a particle diameter of 45 nm or more, the coefficient of variation of particle diameter, the particle shape, and the number percentage of solid particles. Similar to the average particle diameter of the particles described above, the number ratio of particles with a particle diameter of 45 nm or larger, the number ratio of solid particles, and the particle shape were determined from TEM images. The particles produced in both the examples and comparative examples were spherical. Furthermore, the coefficient of variation (CV value) of the particle diameter was calculated using the following formula (5).

[0200]

number

[0201] (In the formula, D is the average particle diameter of the particles, D i (where n represents the particle diameter of each individual particle, and n represents the number of particles measured (300 in this case).)

[0202] (9) Particle 29 Percentage of peak area representing the Q4 structure as determined by Si-NMR analysis The particle dispersion is placed in a dedicated zirconia sample tube and measured using a 6mmφ solid-state probe on an NMR spectrometer (Agilent VNMRS-600) without sample rotation, employing a single-pulse non-decoupling method. Polydimethylsiloxane is used as the secondary standard, with a chemical shift of -34.44 ppm. The obtained spectrum is analyzed using the Origin software, with waveform separation performed and the area of ​​each peak calculated. More specifically, 29The area of ​​the peak appearing at chemical shifts of -78 to -88 ppm (Q1), -88 to -98 ppm (Q2), -98 to -108 ppm (Q3), and -108 to -120 ppm (Q4) in Si-NMR spectroscopy was calculated as (Q4 / ΣQ) × 100. Here, ΣQ = Q1 + Q2 + Q3 + Q4.

[0203] (10) Functional groups contained in the outer shell of the particle The presence or absence of functional groups in the particle shell, and their types, were determined by the following method.

[0204] First, the dispersion was dried in an evaporator, and then dried at 150°C. The dried powder was then subjected to diffuse reflectance analysis using a Fourier transform infrared spectrometer (FT-IR) (FT / IR-6100, manufactured by JASCO Corporation) in the wavenumber region of 700 cm². -1 ~4000cm -1 The detector is TGS, and the resolution is 4.0 cm. -1 The measurement was performed 50 times to accumulate the data, and peaks were detected. The functional groups were then identified by referring to the organic compound spectral database SDBS (https: / / sdbs.db.aist.go.jp (National Institute of Advanced Industrial Science and Technology, 2021.01)).

[0205] (11) Carbon content The dispersion was centrifuged for 30 minutes using a small ultracentrifuge (Hitachi Koki Co., Ltd. CS150GXL) at a temperature of 10°C and a rotation speed of 1,370,000 rpm (1,000,000 G). The precipitate from the treated solution was collected and vacuum-dried at 120°C for 24 hours to obtain particulate powder. The carbon content of the particles in this powder was measured using a carbon-sulfur analyzer (LECO Japan Co., Ltd. CS844).

[0206] (12) Solid content of organosilicon compounds having functional groups The dispersion was centrifuged for 30 minutes using a small ultracentrifuge (Hitachi Koki Co., Ltd. CS150GXL) at a temperature of 10°C and a rotation speed of 1,370,000 rpm (1,000,000 G). The precipitate from the treated solution was collected and vacuum-dried at 120°C for 24 hours to obtain particulate powder. The amount of mass loss before and after heating to 500°C was measured using a thermogravimetric differential thermal analyzer (Hitachi High-Tech Science Co., Ltd. TG / DTA EXSTAR6000 MSD), and the amount of silicon derived from the organosilicon compound was determined from the difference with the original particle amount. Next, the amount of solids derived from the organosilicon compound (R) was determined from the structure of the organosilicon compound used for surface treatment. n -SiO (4-n) / 2 The amount was converted to a quantity, and the solid content of the organosilicon compound having a functional group was determined.

[0207] (13) Content of metallic elements and metallic impurities in the particles The content of metallic elements (alkali metals, alkaline earth metals, Al, Ag, Co, Cr, Cu, Fe, In, Mn, Ni, Pd, Sb, Si, Sn, Th, Ti, U, Zn, and Zr, etc.) in the particles was determined by dissolving the particles in hydrofluoric acid, heating to remove the hydrofluoric acid, adding pure water as needed, and measuring the resulting solution using an ICP inductively coupled plasma emission spectrometer (ICPM-8500, Shimadzu Corporation). For metallic elements other than the impurities mentioned above, the total amount of metallic elements other than carbon contained in the particles was calculated to equal 100 parts by mass on an oxide basis.

[0208] (14) Solid content concentration A 1.0 g sample was taken and dried at 200°C for 3.0 hours. The ratio of the mass of the dried sample to the mass of the sample before drying was determined and defined as the solid content concentration.

[0209] <Manufacturing of coating solution for forming anti-reflective coatings> A coating solution for forming an anti-reflective film with a solid content of 10.0% by mass was prepared by mixing 34.15 g of a PGME dispersion of these particles (S1), 2.23 g of a polyfunctional acrylate resin (Light Acrylate DPE-6A, manufactured by Kyoeisha Chemical Co., Ltd.), 0.25 g of a bifunctional acrylate resin (SR-238F, manufactured by Tomoe Engineering Co., Ltd.), 0.15 g of reactive silicone oil (KF-2012, manufactured by Shin-Etsu Chemical Co., Ltd.), 1.23 g of silicone-modified polyurethane acrylate (Shiko UT-4314, manufactured by Mitsubishi Chemical Corporation, solid content concentration 30% by mass), 1.80 g of a photopolymerization initiator (Omnirad TPO H, manufactured by IGM RESINS BV), 44.19 g of isopropyl alcohol, and 16.00 g of isopropyl glycol.

[0210] <Manufacturing of coated substrates> This coating solution was applied to a 2-inch square glass substrate (Corning #1737) using a spin coater, dried at 80°C for 2 minutes, and then subjected to a 600 mJ / cm² test. 2 The substrate with the coating was manufactured by curing it with ultraviolet light.

[0211] The coated substrate was measured for the following items. The properties of the coating solution and the coated substrate, as well as the measurement results of the coated substrate, are shown in Table 7 (the same applies to the following examples and comparative examples).

[0212] (15) Film thickness and refractive index of the coating The film thickness and refractive index of the coated substrate were calculated by simulation from the spectral reflectance obtained using a microfilm thickness meter (OPTM-F1, manufactured by Otsuka Electronics Co., Ltd.). The refractive index was evaluated by classifying these values ​​as follows. Criteria for evaluating the refractive index of coatings; 1.35 or less: ◎◎ 1.36~1.38: ◎ 1.39~1.41: ○ 1.42~1.44:△ Over 1.44 :×

[0213] (16) Total light transmittance and haze The total light transmittance and haze of the coated substrates were measured using a haze meter (NDH-5000, manufactured by Nippon Denshoku Industries Co., Ltd.). These were classified and evaluated as follows. Evaluation criteria for total light transmittance; 95.0% or higher: ◎◎ 93.0% or higher, less than 95.0%: ◎ 91.5% or more and less than 93.0%: ○ 90.0% or more and less than 91.5%: △ Less than 90.0%: × Hayes' evaluation criteria; 0.3% or less: ◎◎ More than 0.3% and less than 0.5%:◎ More than 0.5% and less than 1.0%:〇 More than 1.0% and less than 1.5%:△ More than 1.5% :×

[0214] (17) Surface irregularities of the pattern on the coated substrate The surface roughness of the patterns on the coated substrates was measured using an atomic force microscope (Dimension Icon, manufactured by Bruker Japan Co., Ltd.) under the conditions of contact mode, scan speed of 0.50 Hz, and scan size of 20 μm × 20 μm. The surface roughness was evaluated by classifying the results as follows. Evaluation criteria; Less than 1.0nm: ◎◎ 1.0nm or more and less than 1.5nm: ◎ 1.5nm or more and less than 2.0nm: ○ 2.0nm or more and less than 2.5nm: △ 2.5nm or more: ×

[0215] [Example 2] In the first step, 50.0 kg of an aqueous sodium aluminate solution with a pH of 12.6 was prepared. In the second step, the heating temperature was set to 50°C, and 0.95 kg of aqueous sodium silicate solution and 0.95 kg of aqueous sodium aluminate solution were added. In the third step, the heating temperature was set to 50°C, and 9.25 kg of aqueous sodium silicate solution and 4.90 kg of aqueous sodium aluminate solution were added. In the fourth step, the heating temperature was set to 50°C, and 53.2 kg of aqueous sodium silicate solution and 8.40 kg of aqueous sodium aluminate solution were added. In the sixth step, the heating rate was set to 0.5°C / min and the heating temperature to 60°C. Except for using 6.0 g of γ-methacryloxypropyltrimethoxysilane for surface treatment of the particles, the particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0216] [Example 3] In the first step, without adding sodium aluminate aqueous solution, 97.6 g of an aqueous dispersion of silica particles (Cataloid SI-550, manufactured by JGC Catalysts & Chemicals Co., Ltd., average particle size 5 nm, solid content concentration 20% by mass) was added to 9902.4 g of pure water, and then 1% by mass of NaOH aqueous solution was added to prepare 10.0 kg of aqueous solution with a pH of 12.5. In the second step, the heating temperature was set to 98°C, and 139.6 kg of sodium silicate aqueous solution and 139.6 kg of sodium aluminate aqueous solution were added. In the third step, the heating temperature was set to 98°C, and 233.8 kg of sodium silicate aqueous solution and 123.8 kg of sodium aluminate aqueous solution were added. In the fourth step, the heating temperature was set to 98°C, 225.0 kg of an aqueous sodium silicate solution with a concentration of 3.0% by mass as SiO2, and 35.5 kg of an aqueous sodium aluminate solution with a concentration of 1.0% by mass as Al2O3. In the sixth step, the heating rate was set to 3.0°C / min, the heating temperature to 160°C, and 1.2 g of γ-methacryloxypropyltrimethoxysilane was used for surface treatment of the particles. Except for these differences, the procedure was the same as in Example 1 to produce a particle dispersion, a coating solution, and a coated substrate.

[0217] [Example 4] In the first step, 30.0 kg of sodium aluminate aqueous solution with a pH of 12.6 was prepared. In the second step, the heating temperature was set to 60°C, 1.0 kg of sodium silicate aqueous solution and 1.0 kg of sodium aluminate aqueous solution were added. In the third step, the heating temperature was set to 60°C, 47.2 kg of sodium silicate aqueous solution and 20.2 kg of sodium aluminate aqueous solution were added. In the fourth step, the heating temperature was set to 60°C, 78.0 kg of sodium silicate aqueous solution and 19.0 kg of sodium aluminate aqueous solution were added. In the sixth step, the heating rate was set to 0.8°C / min, the heating temperature to 80°C, and 4.0 g of γ-methacryloxypropyltrimethoxysilane was used for surface treatment of the particles. The particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0218] [Example 5] In the first step, without adding an aqueous sodium aluminate solution, 97.6 g of an aqueous dispersion of silica particles (Cataloid SI-550, manufactured by JGC Catalysts & Chemicals Co., Ltd.) was mixed with 9902.4 g of pure water, and then an aqueous NaOH solution with a concentration of 1% by mass was added to prepare 10.0 kg of an aqueous solution with a pH of 12.5. In the second step, the heating temperature was set to 85°C, and 36.6 kg of an aqueous sodium silicate solution with a concentration of 3.0% by mass as SiO2 and 12.2 kg of an aqueous sodium aluminate solution with a concentration of 3.0% by mass as Al2O3 were prepared. In the third step, the heating temperature was set to 85°C, and the aqueous sodium silicate solution was heated to 152.0°C. Except for using 96.7 kg of sodium aluminate aqueous solution in the fourth step, setting the heating temperature to 85°C, 264.0 kg of sodium silicate aqueous solution, and 88.0 kg of sodium aluminate aqueous solution in the sixth step, setting the heating rate to 2.8°C / min and the heating temperature to 140°C, and using 0.4 g of γ-methacryloxypropyltrimethoxysilane for surface treatment of the particles, a particle dispersion, a coating solution, and a coated substrate were manufactured in the same manner as in Example 1.

[0219] [Example 6] Except for the following differences, a particle dispersion, a coating solution, and a coated substrate were manufactured in the same manner as in Example 1: in the second step, 12.2 kg of sodium silicate aqueous solution and 12.2 kg of sodium aluminate aqueous solution were used; in the third step, 14.3 kg of sodium silicate aqueous solution with a concentration of 3.0% by mass as SiO2 and 7.57 kg of sodium aluminate aqueous solution with a concentration of 1.0% by mass as Al2O3 were used; and in the fourth step, 50.5 kg of sodium silicate aqueous solution and 7.97 kg of sodium aluminate aqueous solution were used.

[0220] [Example 7] In the second step, 37.2 kg of aqueous sodium silicate solution and 37.2 kg of aqueous sodium aluminate solution were used; in the third step, 82.5 kg of aqueous sodium silicate solution and 27.5 kg of aqueous sodium aluminate solution were used; in the fourth step, 36.1 kg of aqueous sodium silicate solution and 5.70 kg of aqueous sodium aluminate solution were used; and in the sixth step, the heating temperature was set to 140°C. Except for using 12.0 g of γ-methacryloxypropyltrimethoxysilane for surface treatment of the particles, the particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0221] [Example 8] Except for the following differences, a particle dispersion, a coating solution, and a coated substrate were manufactured in the same manner as in Example 1: in the second step, 6.25 kg of sodium silicate aqueous solution and 6.25 kg of sodium aluminate aqueous solution were used; in the third step, 25.1 kg of sodium silicate aqueous solution and 13.3 kg of sodium aluminate aqueous solution were used; and in the fourth step, 57.2 kg of sodium silicate aqueous solution and 4.40 kg of sodium aluminate aqueous solution were used.

[0222] [Example 9] In the first step, 30.0 kg of sodium aluminate aqueous solution with a pH of 12.6 is prepared. In the second step, the heating temperature is set to 60°C, 0.95 kg of sodium silicate aqueous solution with a concentration of 0.9 mass% as SiO2 and 0.95 kg of sodium aluminate aqueous solution with a concentration of 0.3 mass% as Al2O3 are prepared. In the third step, the heating temperature is set to 60°C, 5.50 kg of sodium silicate aqueous solution with a concentration of 0.9 mass% as SiO2 and Al2O3 are prepared. Except for using 2.36 kg of a 0.3% by mass aqueous sodium aluminate solution, 63.4 kg of a 0.9% by mass aqueous sodium silicate solution with a concentration of SiO2 and 10.0 kg of a 0.3% by mass aqueous sodium aluminate solution with a concentration of Al2O3 in the fourth step, and setting the heating temperature to 60°C, 63.4 kg of a 0.9% by mass aqueous sodium silicate solution and 10.0 kg of a 0.3% by mass aqueous sodium aluminate solution in the sixth step, the particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0223] [Example 10] In the first step, 30.0 kg of sodium aluminate aqueous solution with a pH of 12.6 was prepared; in the second step, 2.35 kg of sodium silicate aqueous solution and 2.35 kg of sodium aluminate aqueous solution were added; in the third step, 60.0 kg of sodium silicate aqueous solution and 20.0 kg of sodium aluminate aqueous solution were added; in the fourth step, 166.0 kg of sodium silicate aqueous solution and 26.2 kg of sodium aluminate aqueous solution were added; and in the sixth step, the particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1, except that the heating temperature was set to 160°C.

[0224] [Example 11] In the first step, without adding an aqueous sodium aluminate solution, 9902.4g of pure water was added to 97.6g of an aqueous dispersion of silica particles (Cataloid SI-550, manufactured by JGC Catalysts & Chemicals Co., Ltd.), and then an aqueous NaOH solution with a concentration of 1% by mass was added to prepare 10.0kg of an aqueous solution with a pH of 12.5. In the second step, 82.2kg of an aqueous sodium silicate solution with a concentration of 2.0% by mass as SiO2 and 27.4kg of an aqueous sodium aluminate solution with a concentration of 2.0% by mass as Al2O3 were prepared. In the third step, 164.0kg of an aqueous sodium silicate solution with a concentration of 2.0% by mass as SiO2 and 23.4kg of an aqueous sodium aluminate solution with a concentration of 2.0% by mass as Al2O3 were prepared. In the fourth step, 200.0kg of aqueous sodium silicate solution and 48.7kg of aqueous sodium aluminate solution were prepared. Except for these differences, the particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0225] [Example 12] Except for the following differences, a particle dispersion, a coating solution, and a coated substrate were manufactured in the same manner as in Example 1: in the second step, 1.52 kg of aqueous sodium silicate and 1.52 kg of aqueous sodium aluminate were used; in the third step, 17.2 kg of aqueous sodium silicate and 9.10 kg of aqueous sodium aluminate were used; and in the fourth step, 25.2 kg of aqueous sodium silicate with a concentration of 2.0% by mass as SiO2 and 2.49 kg of aqueous sodium aluminate with a concentration of 2.0% by mass as Al2O3 were used.

[0226] [Example 13] Except for the following differences, a particle dispersion, a coating solution, and a coated substrate were manufactured in the same manner as in Example 1: in the second step, 18.5 kg of sodium silicate aqueous solution and 18.5 kg of sodium aluminate aqueous solution were used; in the third step, 39.0 kg of sodium silicate aqueous solution and 24.8 kg of sodium aluminate aqueous solution were used; and in the fourth step, 36.0 kg of sodium silicate aqueous solution and 8.75 kg of sodium aluminate aqueous solution were used.

[0227] [Example 14] In the first step, 30.0 kg of sodium aluminate aqueous solution with a pH of 12.6 was prepared. In the second step, the heating temperature was set to 70°C, 1.57 kg of sodium silicate aqueous solution and 1.57 kg of sodium aluminate aqueous solution were added. In the third step, the heating temperature was set to 70°C, 22.8 kg of sodium silicate aqueous solution and 12.1 kg of sodium aluminate aqueous solution were added. In the fourth step, the heating temperature was set to 70°C, 180.0 kg of sodium silicate aqueous solution and 28.4 kg of sodium aluminate aqueous solution were added. In the sixth step, the heating rate was set to 0.5°C / min, the heating temperature to 80°C, and 5.0 g of γ-methacryloxypropyltrimethoxysilane was used for surface treatment of the particles. The particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0228] [Example 15] In the first step, without adding an aqueous sodium aluminate solution, 9934.4g of pure water was added to 65.6g of an aqueous dispersion of silica particles (Cataloid SI-30, manufactured by JGC Catalysts & Chemicals Co., Ltd., average particle size 12nm, solid content concentration 30.5% by mass), and then an aqueous NaOH solution with a concentration of 1% by mass was added to prepare 10.0kg of an aqueous solution with a pH of 12.5. In the second step, 4.60kg of aqueous sodium silicate solution and 9.20kg of aqueous sodium aluminate solution with a concentration of 1.5% by mass as Al2O3 were added. In the third step, 13.2kg of aqueous sodium silicate solution and 4.40kg of aqueous sodium aluminate solution were added. In the fourth step, 28.5kg of aqueous sodium silicate solution with a concentration of 0.6% by mass as SiO2 and 4.50kg of aqueous sodium aluminate solution with a concentration of 0.2% by mass as Al2O3 were added. The particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0229] [Example 16] Except for the following differences, a particle dispersion, a coating solution, and a coated substrate were manufactured in the same manner as in Example 1: in the second step, 1.52 kg of sodium silicate aqueous solution and 1.52 kg of sodium aluminate aqueous solution were used; in the third step, 19.0 kg of sodium silicate aqueous solution and 14.3 kg of sodium aluminate aqueous solution were used; and in the fourth step, 61.3 kg of sodium silicate aqueous solution and 9.68 kg of sodium aluminate aqueous solution were used.

[0230] [Example 17] In the first step, without adding an aqueous sodium aluminate solution, 97.6 g of an aqueous dispersion of silica particles (Cataloid SI-550, manufactured by JGC Catalysts & Chemicals Co., Ltd.) was mixed with 9902.4 g of pure water, and then an aqueous NaOH solution with a concentration of 1% by mass was added to prepare 10.0 kg of an aqueous solution with a pH of 12.5. In the second step, 183.6 kg of aqueous sodium silicate solution and 20.4 kg of aqueous sodium aluminate solution with a concentration of 1.5% by mass as Al2O3 were prepared. In the third step, 137.0 kg of aqueous sodium silicate solution with a concentration of 3.0% by mass as SiO2 was prepared as Al2O3. In the fourth step, 11.1 kg of an aqueous sodium aluminate solution with a concentration of 3.0% by mass was used. In the sixth step, 128.6 kg of an aqueous sodium silicate solution with a concentration of 3.0% by mass as SiO2 and 3.30 kg of an aqueous sodium aluminate solution with a concentration of 3.0% by mass as Al2O3 were used. In the sixth step, the heating rate was set to 0.5°C / min and the heating temperature to 80°C. The particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0231] [Example 18] In the second step, 37.2 kg of sodium silicate aqueous solution and 37.2 kg of sodium aluminate aqueous solution were used; in the third step, 62.5 kg of sodium silicate aqueous solution and 33.1 kg of sodium aluminate aqueous solution were used; in the fourth step, 74.0 kg of sodium silicate aqueous solution and 11.7 kg of sodium aluminate aqueous solution were used; and in the sixth step, the pH was set to 10.0, the heating rate to 0.5°C / min, and the heating temperature to 40°C. The particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0232] [Example 19] In the sixth step, a dispersion of particles, a coating solution, and a substrate with a film were produced in the same manner as in Example 1, except that the pH was 11.0, the heating rate was 2.5 °C / min, and the heating temperature was 180 °C.

[0233] [Example 20] In the surface treatment of particles with an organosilicon compound, a dispersion of particles, a coating solution, and a substrate with a film were produced in the same manner as in Example 1, except that tetraethoxysilane (ethyl orthosilicate ES28 manufactured by Tama Chemical Co., Ltd.) was used as the organosilicon compound.

[0234] [Example 21] In the surface treatment of particles with an organosilicon compound, a dispersion of particles, a coating solution, and a substrate with a film were produced in the same manner as in Example 1, except that γ-acryloxypropyltrimethoxysilane (KBM-5103 manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the organosilicon compound.

[0235] [Comparative Example 1] In the first step, 50.0 kg of an aqueous sodium aluminate solution with a pH of 12.6 was prepared. In the second step, the heating temperature was 50 °C, 0.95 kg of an aqueous sodium silicate solution and 0.95 kg of an aqueous sodium aluminate solution were used. In the third step, the heating temperature was 50 °C, 9.25 kg of an aqueous sodium silicate solution and 4.90 kg of an aqueous sodium aluminate solution were used. In the fourth step, the heating temperature was 50 °C, 21.2 kg of an aqueous sodium silicate solution and 3.35 kg of an aqueous sodium aluminate solution were used. A dispersion of particles, a coating solution, and a substrate with a film were produced in the same manner as in Example 1.

[0236] [Comparative Example 2] In the first step, without adding an aqueous sodium aluminate solution, 9934.4g of pure water was added to 65.6g of an aqueous dispersion of silica particles (Cataloid SI-30, manufactured by JGC Catalysts & Chemicals Co., Ltd.), and then an aqueous NaOH solution with a concentration of 1% by mass was added to prepare 10.0kg of an aqueous solution with a pH of 12.5. In the second step, the heating temperature was set to 98°C, 13.1kg of aqueous sodium silicate solution and 13.1kg of aqueous sodium aluminate solution were added. In the third step, the heating temperature was set to 98°C, 38.0kg of aqueous sodium silicate solution and 20.1kg of aqueous sodium aluminate solution were added. In the fourth step, the heating temperature was set to 98°C, 78.0kg of aqueous sodium silicate solution and 12.3kg of aqueous sodium aluminate solution were added. In the sixth step, the heating rate was set to 3.0°C / min and the heating temperature was set to 160°C. The particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0237] [Comparative Example 3] Except for the following differences, a particle dispersion, a coating solution, and a coated substrate were manufactured in the same manner as in Example 1: in the second step, 1.52 kg of sodium silicate aqueous solution and 1.52 kg of sodium aluminate aqueous solution were used; in the third step, 44.1 kg of sodium silicate aqueous solution and 14.7 kg of sodium aluminate aqueous solution were used; and in the fourth step, 180.0 kg of sodium silicate aqueous solution and 13.9 kg of sodium aluminate aqueous solution were used.

[0238] [Comparative Example 4] In the first step, without adding an aqueous sodium aluminate solution, 19804.8g of pure water was added to 195.2g of an aqueous dispersion of silica particles (Cataloid SI-550, manufactured by JGC Catalysts & Chemicals Co., Ltd.), and then an aqueous NaOH solution with a concentration of 1% by mass was added to prepare 20.0kg of an aqueous solution with a pH of 12.5. In the second step, the heating temperature was set to 60°C, 4.00kg of an aqueous sodium silicate solution with a concentration of 0.9% by mass as SiO2 and 4.00kg of an aqueous sodium aluminate solution with a concentration of 0.3% by mass as Al2O3 were added. In the third step, the heating temperature was set to 60°C, 12.3kg of aqueous sodium silicate solution and 3.00kg of aqueous sodium aluminate solution were added. In the fourth step, the heating temperature was set to 60°C, 37.0kg of aqueous sodium silicate solution and 2.85kg of aqueous sodium aluminate solution were added. The particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1, except that the heating temperature was set to 60°C.

[0239] [Comparative Example 5] In the second step, 59.9 kg of sodium silicate aqueous solution and 59.9 kg of sodium aluminate aqueous solution were used; in the third step, 109.0 kg of sodium silicate aqueous solution and 57.7 kg of sodium aluminate aqueous solution were used; in the fourth step, 97.0 kg of sodium silicate aqueous solution and 15.3 kg of sodium aluminate aqueous solution were used; and in the sixth step, the heating rate was set to 2.5°C / min and the heating temperature to 180°C. The particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1, except that the process was carried out in the second step, 59.9 kg of sodium silicate aqueous solution and 59.9 kg of sodium aluminate aqueous solution were used; in the third step, 109.0 kg of sodium silicate aqueous solution and 57.7 kg of sodium aluminate aqueous solution were used; in the fourth step, 97.0 kg of sodium silicate aqueous solution and 15.3 kg of sodium aluminate aqueous solution were used; and in the sixth step, the heating rate was set to 2.5°C / min and the heating temperature to 180°C.

[0240] [Comparative Example 6] In the first step, without adding an aqueous sodium aluminate solution, 9934.4g of pure water was added to 65.6g of an aqueous dispersion of silica particles (Cataloid SI-30, manufactured by JGC Catalysts & Chemicals Co., Ltd.), and then an aqueous NaOH solution with a concentration of 1% by mass was added to prepare 10.0kg of an aqueous solution with a pH of 12.5. In the second step, 30.8kg of aqueous sodium silicate solution and 30.8kg of aqueous sodium aluminate solution were added. In the third step, 52.5kg of aqueous sodium silicate solution and 24.8kg of aqueous sodium aluminate solution were added. In the fourth step, 52.0kg of aqueous sodium silicate solution and 8.20kg of aqueous sodium aluminate solution were added. Except for these differences, the particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0241] [Comparative Example 7] In the second step, 37.2 kg of sodium silicate aqueous solution and 37.2 kg of sodium aluminate aqueous solution were used; in the third step, 82.5 kg of sodium silicate aqueous solution and 27.5 kg of sodium aluminate aqueous solution were used; in the fourth step, 26.7 kg of sodium silicate aqueous solution and 8.90 kg of sodium aluminate aqueous solution were used; and in the sixth step, the heating rate was set to 0.8°C / min and the heating temperature to 80°C. The particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1, except that the process was carried out in the second step, 37.2 kg of sodium silicate aqueous solution and 37.2 kg of sodium aluminate aqueous solution were used; in the third step, 82.5 kg of sodium silicate aqueous solution and 27.5 kg of sodium aluminate aqueous solution were used; in the fourth step, 26.7 kg of sodium silicate aqueous solution and 8.90 kg of sodium aluminate aqueous solution were used; and in the sixth step, the heating rate was set to 0.8°C / min and the heating temperature to 80°C.

[0242] [Comparative Example 8] In the first step, without adding an aqueous sodium aluminate solution, 9902.4g of pure water was added to 97.6g of an aqueous dispersion of silica particles (Cataloid SI-550, manufactured by JGC Catalysts & Chemicals Co., Ltd.), and then an aqueous NaOH solution with a concentration of 1% by mass was added to prepare 10.0kg of an aqueous solution with a pH of 12.5. In the second step, 72.2kg of an aqueous sodium silicate solution with a concentration of 2.0% by mass as SiO2 and 3.00kg of an aqueous sodium aluminate solution with a concentration of 2.0% by mass as Al2O3 were prepared. In the third step, 101.4kg of aqueous sodium silicate solution and 33.8kg of aqueous sodium aluminate solution were prepared. In the fourth step, 209.0kg of aqueous sodium silicate solution and 33.0kg of aqueous sodium aluminate solution were prepared. Except for these differences, the particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0243] [Comparative Example 9] In the first step, without adding an aqueous sodium aluminate solution, 97.6 g of an aqueous dispersion of silica particles (Cataloid SI-550, manufactured by JGC Catalysts & Chemicals Co., Ltd.) was mixed with 9902.4 g of pure water, and then an aqueous NaOH solution with a concentration of 1% by mass was added to prepare 10.0 kg of an aqueous solution with a pH of 12.5. In the second step, 26.0 kg of an aqueous sodium silicate solution with a concentration of 3.0% by mass as SiO2 and 78.0 kg of an aqueous sodium aluminate solution with a concentration of 3.0% by mass as Al2O3 were used, but the procedure was the same as in Example 1. However, the composite oxide particles a obtained in this second step became aggregated particles with an average particle diameter of 3 μm or more, so the subsequent steps were not carried out, and the coating solution and coated substrate were not manufactured.

[0244] [Comparative Example 10] In the first step, 30.0 kg of sodium aluminate aqueous solution with a pH of 12.6 was prepared. In the second step, the heating temperature was set to 50°C, and 0.95 kg of sodium silicate aqueous solution and 0.95 kg of sodium aluminate aqueous solution were added. In the third step, the heating temperature was set to 50°C, and 8.85 kg of sodium silicate aqueous solution with a concentration of 0.9 mass% as SiO2 and 2.15 kg of sodium aluminate aqueous solution with a concentration of 0.3 mass% as Al2O3 were added. In the fourth step, the heating temperature was set to 50°C, and 142.0 kg of sodium silicate aqueous solution and 22.4 kg of sodium aluminate aqueous solution were added. In the sixth step, the heating rate was set to 0.8°C / min and the heating temperature was set to 80°C. The process was carried out in the same manner as in Example 1, except that the particle dispersion, coating solution, and coated substrate were produced.

[0245] [Comparative Example 11] In the first step, 30.0 kg of sodium aluminate aqueous solution with a pH of 12.6 was prepared. In the second step, the heating temperature was set to 60°C, 1.0 kg of sodium silicate aqueous solution and 1.0 kg of sodium aluminate aqueous solution were added. In the third step, the heating temperature was set to 60°C, 47.2 kg of sodium silicate aqueous solution and 20.2 kg of sodium aluminate aqueous solution were added. In the fourth step, the heating temperature was set to 60°C, 78.0 kg of sodium silicate aqueous solution and 19.0 kg of sodium aluminate aqueous solution were added. In the sixth step, the heating rate was set to 10°C / min, the heating temperature to 80°C, and 4.0 g of γ-methacryloxypropyltrimethoxysilane was used for surface treatment of the particles. Except for these differences, the particle dispersion, coating solution, and coated substrate were manufactured in the same manner as in Example 1.

[0246] [Comparative Example 12] In the second step, 37.2 kg of an aqueous sodium silicate solution and 37.2 kg of an aqueous sodium aluminate solution were used. In the third step, 82.5 kg of an aqueous sodium silicate solution and 27.5 kg of an aqueous sodium aluminate solution were used. In the fourth step, 36.1 kg of an aqueous sodium silicate solution and 5.70 kg of an aqueous sodium aluminate solution were used. In the sixth step, the heating temperature was 30 °C. A dispersion of particles, a coating solution, and a substrate with a film were produced in the same manner as in Example 1, except that 12.0 g of γ-methacryloxypropyltrimethoxysilane was used for the surface treatment of the particles.

[0247] [Comparative Example 13] In the first step, 30.0 kg of an aqueous sodium aluminate solution with a pH of 12.6 was prepared. In the second step, the heating temperature was 60 °C, 1.0 kg of an aqueous sodium silicate solution and 1.0 kg of an aqueous sodium aluminate solution were used. In the third step, the heating temperature was 60 °C, 47.2 kg of an aqueous sodium silicate solution and 20.2 kg of an aqueous sodium aluminate solution were used. In the fourth step, the heating temperature was 60 °C, 78.0 kg of an aqueous sodium silicate solution and 19.0 kg of an aqueous sodium aluminate solution were used. In the sixth step, the heating rate was 0.8 °C / min and the heating temperature was 250 °C. A dispersion of particles, a coating solution, and a substrate with a film were produced in the same manner as in Example 1, except that 4.0 g of γ-methacryloxypropyltrimethoxysilane was used for the surface treatment of the particles.

[0248] [Table 4]

[0249] [Table 5]

[0250] [Table 6]

[0251] [Table 7]

Claims

1. A particle having a silicon-containing outer shell and a cavity inside, Image analysis of the aforementioned particles revealed that the average particle diameter is 10 to 35 nm, the refractive index is 1.15 to 1.38, and the average diameter of the cavity is 4 to 29 nm. Particles characterized in that the haze of a dispersion of the particles, in which the particles are dispersed in a monomer with a refractive index of 1.52 and the solid content concentration of the particles is 20% by mass, is 50% or less.

2. The Rayleigh ratio (R) of the particle can be determined by the following formula (1) Θ ) is 8.0 x 10 ５ The particle according to claim 1, characterized in that it is as follows: [Math 1] (In the formula, n １ is the particle refractive index, n ２ (where is the solvent refractive index (= 1.52), and d represents the average particle size (nm) determined by image analysis.)

3. The Rayleigh ratio (R) is calculated using the following formula (2). Θ ) and the product of the number of particles per unit volume (N) (R Θ ×N) is 4.0 × 10 １０ The particle according to claim 1 or 2, characterized in that it is as follows: [Math 2] (where n １ is the particle refractive index, n ２ is the solvent refractive index (= 1.52), d is the average particle diameter (nm) by image analysis, N is the number of particles per unit volume (= 1000 (nm) × 1000 (nm) × 1000 (nm) ÷ particle volume (nm ３ / piece).)

4. The refractive index of the outer shell (n) can be determined by the following formula (3). ｓ The particle according to claim 1, characterized in that ) is 1.42 or less. [Math 3] (In the formula, d is the average particle diameter determined by image analysis, d ｃ n is the average value of the diameter of the particle cavity. ｐ is the particle refractive index, n ｃ (This represents the refractive index of the particle cavity.)

5. The particles according to claim 1, characterized in that the proportion of particles with a particle diameter of 45 nm or more, as determined by image analysis, is 10% or less.

6. The particle according to claim 1, characterized in that the coefficient of variation of particle size is 40% or less.

7. The particles according to claim 1, characterized in that the carbon content is 0.1 to 5.0% by mass.

8. The aforementioned particles ２９ In Si-NMR analysis, the Q of silicon atoms appears when the chemical shift is between -78 and -120 ppm. １ ~Q ４ The Q of the silicon atom in which the chemical shift relative to the sum of the areas of each peak representing the structure appears to be between -108 and -120 ppm. ４ The particle according to claim 1, characterized in that the proportion of the area of ​​the peak representing the structure is less than 85%.

9. The particle according to claim 1, characterized in that the particle contains at least one functional group selected from alkyl groups, acryloyl groups, (meth)acryloyl groups, vinyl groups, mercapto groups, and epoxy groups.

10. The first step is to prepare an alkaline aqueous solution containing amphoteric elements, A solution of a silicon-containing compound and an aqueous solution of an alkali-soluble inorganic element compound other than silicon are used, and the silicon oxide is SiO ２ When the oxide of the inorganic element is represented as MOx, the molar ratio (MOx / SiO ２ A second step involves simultaneously adding the above-mentioned alkaline aqueous solution to the above-mentioned alkaline aqueous solution such that the ratio is 0.1 to 2.0, thereby preparing a dispersion of composite oxide particles a having an average particle size of 5 to 29 nm. Next, a molar ratio smaller than the molar ratio of the second step (MOx / SiO ２ A third step involves adding a solution of a silicon-containing compound and an aqueous solution of an alkali-soluble inorganic element compound other than silicon to the dispersion of the composite oxide particles a to prepare a dispersion of composite oxide particles b having an average particle size of 6 to 33 nm. Next, a molar ratio smaller than the molar ratio of the third step (MOx / SiO ２ The fourth step involves adding a solution of a silicon-containing compound and an aqueous solution of an alkali-soluble inorganic element compound other than silicon to the dispersion of the composite oxide particles b to prepare a dispersion of composite oxide particles c having an average particle size of 10 to 35 nm. Next, a fifth step is to add acid to the dispersion of the composite oxide particles c to remove at least some of the elements other than silicon that constitute the composite oxide particles c, thereby preparing a dispersion of silica particles d. A method for producing a dispersion of hollow silica particles, comprising a sixth step of heating the dispersion of the silica particles d to 40 to 180°C at a heating rate of 3.0°C / min or less.

11. The method for producing particles according to claim 10, characterized in that, after the sixth step, at least one of the organosilicon compound shown in the following formula (4) and its partial hydrolysate is added. R ｎ -SiX ４－ｎ ...Form (4) (In the formula, R is an unsubstituted or substituted hydrocarbon group having 1 to 10 carbon atoms, X is an alkoxy group, hydroxyl group, or hydrogen atom having 1 to 4 carbon atoms, and n is an integer from 0 to 3.)

Images