Oxide particles with controlled color properties, and coating or film compositions containing such oxide particles.

Abstract

The objective is to provide oxide particles with controlled color characteristics. In light of these circumstances, the present invention provides oxide particles or a method for producing oxide particles that can be supplied stably with low energy and resource conservation. [Solution] Silicon compound coated oxide particles in which at least a portion of the surface of oxide particles is coated with a silicon compound, wherein the oxide constituting the oxide particles is iron oxide, the silicon compound can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles, the M-OH bond / MO bond ratio of the oxide particles is 1% or more and 30% or less, and the wavelength of the oxide particles is from 780 nm to 2500 nm. Silicon compound coated oxide particles characterized by having an average reflectance of 50% or more for light rays of an nm magnitude.

Description

[Technical Field]

[0001] The present invention relates to oxide particles with controlled color properties, and to coating or film-like compositions containing such oxide particles. [Background technology]

[0002] Oxide particles are used in a wide range of fields, such as sunscreens, lipsticks, and foundations in cosmetics, as well as paints used on exterior walls, signs, vehicles, and glass. This is because the properties of oxide particles, such as ultraviolet absorption and near-infrared reflection, change depending on the type of metallic or metalloid element they contain. However, when oxide particles are intended to be applied to the human body, such as in cosmetics, there are very high demands for aesthetics, texture, and safety. At the same time, when oxide particles are used in paints for building materials, exterior walls, signs, vehicles, etc., there are also very high demands for vivid color and design appeal.

[0003] Therefore, methods have been provided to improve properties such as color characteristics, ultraviolet absorption characteristics, and near-infrared reflection characteristics of oxides such as iron oxide and zinc oxide, by methods such as micronizing them (see Patent Documents 1 and 2) or by complex oxide formation (see Patent Documents 3 and 4), in which oxides are produced using multiple elements other than iron or zinc as elements other than oxygen that constitute the oxide.

[0004] However, while miniaturization can improve the transparency of particulate dispersions, controlling reflectivity, transmission and absorption properties, and color properties such as hue and saturation remains difficult. Furthermore, in composite oxide formation, the properties of the oxide change significantly depending on the type of metal used, making control of color properties particularly challenging. For these reasons, precise and delicate control of the properties of oxide particles has been difficult.

[0005] Furthermore, Patent Document 5 describes silica-coated metal oxide particles that have been further surface-treated with a hydrophobic agent such as dimethylethoxysilane, but this merely involves treating the particles with a hydrophobic agent to improve their dispersibility in oily dispersion media such as polyglyceryl triisostearate, silicone oil, and squalane for cosmetic purposes. Also, Patent Document 5 describes the infrared absorption spectrum at 1150-1250 cm⁻¹. -1 The peak observed is described as the absorption of bending vibrations of Si-OH, but it should normally be attributed to Si-O bonds, and the description of Si-OH is a clear error. Therefore, Patent Document 5 does not control the amount of Si-OH groups contained in silica-coated metal oxides or the ratio of M-OH bonds to MO bonds. In other words, Patent Document 5 also did not disclose oxide particles with controlled color properties.

[0006] Furthermore, Patent Documents 6 and 7, which disclose the present applicant's invention, describe a method for producing uniform oxide nanoparticles using a method of depositing various nanoparticles such as iron oxide between relatively rotating processing surfaces that can move toward and away from each other. However, while Patent Document 6 describes the differentiation between oxides and hydroxides, and Patent Document 7 describes the production of uniform oxides, neither describes a method for producing oxides with controllable color properties. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2009-263547 [Patent Document 2] International Publication No. 1998 / 026011 Pamphlet [Patent Document 3] Special Publication No. 2010-530448 [Patent Document 4] Japanese Patent Publication No. 2013-249393 [Patent Document 5] International Publication No. 2000 / 42112 Pamphlet [Patent Document 6] Patent No. 4868558 [Patent Document 7] International Publication No. 2009 / 008393 brochure [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In light of these circumstances, the present invention aims to provide oxide particles with controlled color properties. In light of these circumstances, the present invention aims to provide oxide particles or a method for producing oxide particles that can be supplied stably with low energy and resource conservation. Because the regular arrangement of atoms is interrupted on the surface of oxide particles, the atoms present on the particle surface are highly reactive and in many cases react with suitable surrounding substances to form surface compounds. In particular, in the case of minute particles of 100 nm or less, the influence of surface atoms becomes large and significant, so precise control is necessary. In order to control the surface compounds of oxide particles and maximize the expected properties, or to compensate for such properties, the present invention aims to control the color properties by controlling the amount of hydroxyl groups contained in the oxide or the ratio of hydroxyl groups. This utilizes the fact that the ratio and morphology of M-OH bonds or M-OH bond / MO bond ratio contained in the oxide change depending on the manufacturing method and changes in the environment after manufacturing. For the near-infrared region with wavelengths from 780 nm to 2500 nm, the present invention aims to control the reflectance. Furthermore, the present invention aims to control reflectance, transmittance, hue, or saturation in the visible region from 380 nm to 780 nm. In addition, the present invention aims to control reflectance or molar extinction coefficient in the ultraviolet region from 190 nm to 380 nm. The inventors of this invention have found a relationship between the ratio of M-OH bonds or the M-OH bond / MO bond ratio contained in oxide particles and the transmission characteristics, absorption characteristics, reflectance characteristics, hue, or saturation of said oxide particles such as iron oxide particles, zinc oxide particles, cerium oxide particles, and cobalt-zinc composite oxide particles, and have completed the present invention by finding that the color characteristics of oxide particles can be improved by controlling the ratio of M-OH bonds or the M-OH bond / MO bond ratio contained in oxide particles. Furthermore, in light of the above circumstances, the present invention aims to provide a coating or film-like composition containing oxide particles with controlled color characteristics. [Means for solving the problem]

[0009] The inventors of the present invention have discovered that the M-OH bond / MO bond ratio of metal oxide particles or metalloid oxide particles (hereinafter sometimes collectively referred to as "oxide particles") is related to the transmission properties, absorption properties, reflection properties, hue, or saturation of the oxide particles, and have completed the present invention.

[0010] In other words, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / MO bond ratio of the above oxide particles is 1% or more and 30% or less. These are silicon compound-coated oxide particles having an average reflectance of 50% or more for light rays with wavelengths from 780 nm to 2500 nm.

[0011] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / MO bond ratio of the above oxide particles is between 13% and 35%. These are silicon compound-coated oxide particles in which the maximum reflectance for light rays with wavelengths from 400 nm to 620 nm is 18% or less.

[0012] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / MO bond ratio of the above oxide particles is between 10% and 28%. These silicon compound-coated oxide particles have an average reflectance of 22% or less for light rays with wavelengths from 620 nm to 750 nm.

[0013] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / MO bond ratio of the above oxide particles is 2% to 25%. L * a * b * In a color system, hue H(=b * / a * These are silicon compound coated oxide particles whose ) is in the range of 0.5 to 0.9.

[0014] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / MO bond ratio of the above oxide particles is between 1% and 31%. The silicon compound-coated oxide particles are characterized in that, in the transmission spectrum of a dispersion obtained by dispersing the above oxide particles in a dispersion medium, the transmittance for light with a wavelength of 380 nm is 5% or less, and the transmittance for light with a wavelength of 600 nm is 80% or more.

[0015] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / MO bond ratio of the above oxide particles is 5% or more and 35% or less. The silicon compound-coated oxide particles are obtained by dispersing the above oxide particles in a dispersion medium, and the average molar extinction coefficient for light rays with wavelengths from 190 nm to 380 nm is 2200 L / (mol·cm) or higher.

[0016] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The above oxide particles contain ester bonds, The M-OH bond / MO bond ratio of the above oxide particles is 5% or more and 30% or less. These are silicon compound-coated oxide particles having an average reflectance of 50% or more for light rays with wavelengths from 780 nm to 2500 nm.

[0017] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / MO bond ratio of the above oxide particles is 1% or more and less than 10%, or greater than 28% and 35% or less. These silicon compound-coated oxide particles have an average reflectance of 22% or higher for light rays with wavelengths of 620 nm to 750 nm compared to the above oxide particles.

[0018] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The above oxide particles are silicon compound-coated oxide particles in which the M-OH bond / MO bond ratio is 30% or more and 47.5% or less, and the average reflectance for light rays with wavelengths from 780 nm to 2500 nm is 70% or more.

[0019] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The above oxide particles are silicon compound-coated oxide particles in which the M-OH bond / MO bond ratio is 30% or more and 40% or less, and the wavelength at which the reflectance is 15% is 375 nm or longer.

[0020] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / MO bond ratio of the above oxide particles is 45% or more and 50% or less. Silicon compound-coated oxide particles in which the ratio of M-OH bonds contained in the above oxide particles is 38% or more and 42% or less, and the average reflectance with respect to light rays having wavelengths from 380 nm to 780 nm is 86% or more.

[0021] The present invention also relates to silicon compound-coated oxide particles in which at least a part of the surface of the oxide particles is coated with a silicon compound, where the oxide constituting the above oxide particles is zinc oxide, the above silicon compound can change the color characteristics of the above oxide particles by coating at least a part of the surface of the above oxide particles, the ratio of M-OH bonds / M-O bonds of the above oxide particles is 31% or more and 50% or less, L * a * b * in the color system, the chroma C (= √((a * )) 2 +(b * )) 2 ) is in the range of 0.5 to 13.

[0022] The present invention also relates to silicon compound-coated oxide particles in which at least a part of the surface of the oxide particles is coated with a silicon compound, where the oxide constituting the above oxide particles is zinc oxide, the above silicon compound can change the color characteristics of the above oxide particles by coating at least a part of the surface of the above oxide particles, the ratio of M-OH bonds / M-O bonds of the above oxide particles is 47% or more and 50% or less, in the transmission spectrum of a dispersion liquid in which the above oxide particles are dispersed in a dispersion medium, the transmittance with respect to light rays having a wavelength of 340 nm is 10% or less, and the average transmittance with respect to light rays having wavelengths from 380 nm to 780 nm is 92% or more.

[0023] The present invention also relates to silicon compound-coated oxide particles in which at least a part of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / MO bond ratio of the above oxide particles is 30% or more and 40% or less. The silicon compound-coated oxide particles are such that, in the transmission spectrum of a dispersion obtained by dispersing the above oxide particles in a dispersion medium, the wavelength at which the transmittance is 15% is 365 nm or higher.

[0024] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / MO bond ratio of the above oxide particles is 30% or more and 50% or less. The silicon compound-coated oxide particles are obtained by dispersing the above oxide particles in a dispersion medium, and the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 700 L / (mol·cm) or higher.

[0025] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / MO bond ratio of the above oxide particles is 31% or more and 50% or less. L * a * b * In a color system, saturation C(=√((a * ) 2 +(b * ) 2)) is in the range of 0.5 to 13, L * a * b * In color systems, L * These are silicon compound-coated oxide particles with a value in the range of 95 to 97.

[0026] Furthermore, the present invention relates to silicon compound coated oxide particles in which at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is cerium oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / MO bond ratio of the above oxide particles is 25% or more and 40% or less. The silicon compound-coated oxide particles are obtained by dispersing the above oxide particles in a dispersion medium, and the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 4000 L / (mol·cm) or more.

[0027] Furthermore, the present invention relates to oxide particles in which the ratio of M-OH bonds contained in the oxide particles is controlled, wherein at least a portion of the surface of a single oxide particle, or the surface of an aggregate formed by the aggregation of multiple oxide particles, is coated with a silicon compound. Preferably, the particle size of the oxide particles or aggregates of oxide particles is between 1 nm and 50 nm.

[0028] Furthermore, in the present invention, it is preferable that the silicon compound includes amorphous silicon oxide.

[0029] Furthermore, the present invention relates to oxide particles composed of iron oxide, The M-OH bond / MO bond ratio of the above oxide particles is 1% or more and 21% or less. In a dispersion liquid in which the above oxide particles are dispersed in a dispersion medium, the oxide particles have an average molar extinction coefficient of 1000 L / (mol·cm) or more for light rays with wavelengths from 190 nm to 380 nm.

[0030] Furthermore, the present invention relates to oxide particles composed of iron oxide, The oxide particles described above have an M-OH bond / MO bond ratio of 1% to 21%, and an average reflectance of 55% or more for light rays with wavelengths from 780 nm to 2500 nm.

[0031] Furthermore, the present invention relates to oxide particles composed of cerium oxide, The oxide particles described above have an M-OH bond / MO bond ratio of 30% or less, and in a dispersion of the oxide particles in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 3500 L / (mol·cm) or more.

[0032] Furthermore, the present invention relates to oxide particles composed of cerium oxide, The oxide particles described above have an M-OH bond / MO bond ratio of 23% or less, and in a dispersion liquid in which the oxide particles are dispersed in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 4000 L / (mol·cm) or more.

[0033] Furthermore, the present invention relates to oxide particles composed of cobalt-zinc composite oxides, The oxide particles described above have an M-OH bond / MO bond ratio of 1% to 33%, and in a dispersion liquid in which the oxide particles are dispersed in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 700 L / (mol·cm) or more.

[0034] Furthermore, the present invention relates to oxide particles composed of silicon-cobalt-zinc composite oxide, The oxide particles described above have an M-OH bond / MO bond ratio of 13% to 40%, and in a dispersion liquid in which the oxide particles are dispersed in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 800 L / (mol·cm) or more.

[0035] Furthermore, in the present invention, it is preferable that the primary particle diameter of the oxide particles is 100 nm or less.

[0036] Furthermore, in this invention, the oxide particles are zinc oxide particles with a primary particle diameter of 50 nm or less. The M-OH bond / MO bond ratio of the above oxide particles is 18% or less. In a dispersion liquid in which the above oxide particles are dispersed in a dispersion medium, the oxide particles have an average molar extinction coefficient of 500 L / (mol·cm) or more for light rays with wavelengths from 200 nm to 380 nm.

[0037] Furthermore, in this invention, the oxide particles are zinc oxide particles with a primary particle diameter of 50 nm or less. The M-OH bond / MO bond ratio of the above oxide particles is 15% or less. In a dispersion liquid in which the above oxide particles are dispersed in a dispersion medium, the oxide particles have an average molar extinction coefficient of 650 L / (mol·cm) or more for light rays with wavelengths from 200 nm to 380 nm.

[0038] Furthermore, in this invention, the oxide particles are zinc oxide particles with a primary particle diameter of 50 nm or less. The above oxide particles have an M-OH bond / MO bond ratio of 14% or less. These oxide particles have an average reflectance of 65% or more for light rays with wavelengths from 780 nm to 2500 nm.

[0039] Furthermore, in this invention, the oxide particles are zinc oxide particles with a primary particle diameter of 50 nm or less. The oxide particles described above have an M-OH bond / MO bond ratio of 14% or less, and in a dispersion liquid in which the oxide particles are dispersed in a dispersion medium, the transmittance to light with a wavelength of 330 nm is 10% or less, and the average transmittance to light with wavelengths from 380 nm to 780 nm is 90% or more.

[0040] Furthermore, in the present invention, it is preferable that the haze value of the oxide particle dispersion obtained by dispersing the above oxide particles in a dispersion medium is 1% or less.

[0041] Furthermore, the present invention can be implemented as a coating or film-like oxide composition containing oxide particles with a controlled M-OH bond / MO bond ratio. [Effects of the Invention]

[0042] According to the present invention, by controlling the M-OH bond / MO bond ratio of metal oxide particles or metalloid oxide particles, oxide particles can be provided in which any of the color characteristics, such as reflectance, transmittance, molar extinction coefficient, hue, or chroma, can be controlled. Since the color characteristics of oxide particles can be precisely controlled by controlling the ratio of M-OH bonds or the M-OH bond / MO bond ratio, it has become easier to design compositions that are more appropriate than conventional methods for the diverse applications and desired properties of oxide particles. [Brief explanation of the drawing]

[0043] [Figure 1] This shows the STEM mapping results of silicon compound-coated iron oxide particles, in which the surface of the iron oxide particles obtained in Examples 1-5 of the present invention is coated with a silicon compound. [Figure 2] This shows the line analysis results of silicon compound-coated iron oxide particles obtained in Examples 1-5 of the present invention, in which the surface of the iron oxide particles is coated with a silicon compound. [Figure 3] This is a STEM mapping result of silicon compound-coated iron oxide particles obtained in Example 1 of the present invention, in which a portion of the surface of the iron oxide particles is coated with a silicon compound. [Figure 4] This is the result of line analysis of silicon compound-coated iron oxide particles obtained in Example 1 of the present invention, in which a portion of the surface of the iron oxide particles is coated with a silicon compound. [Figure 5] These are the IR measurement results for silicon compound-coated iron oxide particles obtained in Example 1 and Example 1-5 of the present invention. [Figure 6] This shows the waveform separation results in the wavenumber region from 100 cm⁻¹ to 1250 cm⁻¹ in the IR measurement results of silicon compound-coated iron oxide particles obtained in Example 1 of the present invention. [Figure 7]This shows the waveform separation results in the wavenumber region from 100 cm⁻¹ to 1250 cm⁻¹ in the IR measurement results of silicon compound-coated iron oxide particles obtained in Examples 1-5 of the present invention. [Figure 8] These are the XRD measurement results of silicon compound-coated iron oxide particles obtained in Examples 1-5 of the present invention. [Figure 9] These are the reflection spectrum measurement results for silicon compound-coated iron oxide particles obtained by the embodiment of the present invention, for light rays with wavelengths from 200 nm to 2500 nm. [Figure 10] This graph shows the average reflectance for light rays with wavelengths from 780 nm to 2500 nm against the M-OH bond / MO bond ratio of silicon compound-coated iron oxide particles obtained by embodiments of the present invention. [Figure 11] This graph shows the average reflectance for light rays with wavelengths from 780 nm to 2500 nm against the M-OH bond / MO bond ratio of silicon compound-coated iron oxide particles obtained by an example in which an aqueous dispersion of silicon compound-coated iron oxide particles of the present invention was heat-treated. [Figure 12] This is the transmission spectrum of a dispersion obtained by dispersing silicon compound-coated iron oxide particles obtained in Examples 1 and 1-5 of the present invention, and iron oxide particles obtained in Example 4, in propylene glycol. [Figure 13] This graph shows the average reflectance for light rays with wavelengths from 780 nm to 2500 nm against the M-OH bond / MO bond ratio of silicon compound-coated iron oxide particles obtained by embodiments of the present invention. [Figure 14] This graph shows the maximum reflectance for light rays with wavelengths from 400 nm to 620 nm against the M-OH bond / MO bond ratio of silicon compound-coated iron oxide particles obtained by the embodiment of the present invention. [Figure 15] This graph shows the average reflectance of silicon compound-coated iron oxide particles obtained by the embodiment of the present invention, with respect to the M-OH bond / MO bond ratio and light rays with wavelengths from 620 nm to 750 nm. [Figure 16]This is a graph of the hue in the L*a*b* color system in relation to the M-OH bond / MO bond ratio of silicon compound-coated iron oxide particles obtained by the embodiments of the present invention. [Figure 17] This graph shows the molar extinction coefficients of the dispersions obtained by Example 1 and Example 1-5 of the present invention, in which silicon compound-coated iron oxide particles are dispersed in propylene glycol, and the dispersion obtained by Example 4, in which iron oxide particles are dispersed in propylene glycol. [Figure 18] This graph shows the average molar extinction coefficient for light rays with wavelengths from 190 nm to 380 nm of a dispersion of silicon compound-coated iron oxide particles obtained in Examples 1, 1-3, 1-4, and 1-5 of the present invention, with respect to the M-OH bond / MO bond ratio of the silicon compound-coated iron oxide particles obtained in propylene glycol. [Figure 19] These are the reflection spectrum measurement results for silicon compound-coated iron oxide particles obtained by Example 1, Example 1-9, and Example 1-10 of the present invention, for light rays with wavelengths from 200 nm to 2500 nm. [Figure 20] These are the IR spectral measurement results of silicon compound-coated iron oxide particles obtained in Examples 1 and 1-9 of the present invention. [Figure 21] This is a STEM mapping result of silicon compound-coated zinc oxide particles, in which the surface of zinc oxide particles obtained in Example 2 of the present invention is coated with a silicon compound. [Figure 22] This is the line analysis result of silicon compound-coated zinc oxide particles obtained in Example 2 of the present invention, in which the surface of the zinc oxide particles is coated with a silicon compound. [Figure 23] This is a STEM mapping result of silicon compound-coated zinc oxide particles obtained in Example 2-4 of the present invention, in which a portion of the surface of the zinc oxide particles is coated with a silicon compound. [Figure 24] This shows the line analysis results of silicon compound-coated zinc oxide particles obtained in Examples 2-4 of the present invention, in which a portion of the surface of the zinc oxide particles is coated with a silicon compound. [Figure 25]These are the reflection spectrum measurement results for silicon compound-coated zinc oxide particles obtained by the embodiment of the present invention, for light rays with wavelengths from 200 nm to 2500 nm. [Figure 26] This graph shows the average reflectance for light rays with wavelengths from 780 nm to 2500 nm against the M-OH bond / MO bond ratio of silicon compound-coated zinc oxide particles obtained by embodiments of the present invention. [Figure 27] These are the reflection spectrum measurement results for the M-OH bond / MO bond ratio of silicon compound-coated zinc oxide particles obtained by the embodiment of the present invention, for light rays with wavelengths from 200 nm to 780 nm. [Figure 28] This graph shows the chrominance in the L*a*b* color system relative to the M-OH bond / MO bond ratio of silicon compound-coated zinc oxide particles obtained by the embodiments of the present invention. [Figure 29] This graph shows the L* value in the L*a*b* color system for the M-OH bond / MO bond ratio of silicon compound-coated zinc oxide particles obtained by the embodiments of the present invention. [Figure 30] These are the transmission spectrum measurements of dispersions obtained by dispersing silicon compound-coated zinc oxide particles obtained in Examples 2, 2-2, 2-3, and 2-4 of the present invention, and zinc oxide particles obtained in Example 5, in propylene glycol. [Figure 31] This graph shows the molar extinction coefficients of dispersions obtained by dispersing silicon compound-coated zinc oxide particles obtained in Examples 2, 2-2, 2-3, and 2-4 of the present invention, and zinc oxide particles obtained in Example 5, in propylene glycol. [Figure 32] This is a TEM image of silicon compound-coated cerium oxide particles obtained in Example 3 of the present invention, in which the surface of cerium oxide is coated with a silicon compound. [Figure 33] This graph shows the molar extinction coefficients of the silicon compound-coated cerium oxide particles obtained in Example 3 of the present invention, and the dispersions obtained in Example 8, which were dispersed in propylene glycol. [Figure 34] This is a schematic diagram of the apparatus used in the method for controlling the M-OH bond / MO bond ratio of oxide particles according to the present invention. [Figure 35] This shows the XRD measurement results of the iron oxide particles obtained in Example 4 of the present invention. [Figure 36] These are the IR measurement results for iron oxide particles obtained in Example 4 and Example 4-4 of the present invention in the wavenumber range of 50 cm⁻¹ to 4000 cm⁻¹. [Figure 37] This shows the waveform separation results of IR measurements of iron oxide particles obtained in Example 4 of the present invention in the wavenumber range of 100 cm⁻¹ to 1250 cm⁻¹. [Figure 38] This shows the waveform separation results of IR measurements of iron oxide particles obtained in Example 4-4 of the present invention in the wavenumber range of 100 cm⁻¹ to 1250 cm⁻¹. [Figure 39] This graph shows the molar extinction coefficients for dispersions obtained by dispersing iron oxide particles obtained in Example 4 and Examples 4-2 to 4-4 in propylene glycol, with respect to measurement wavelengths from 190 nm to 780 nm. [Figure 40] This graph shows the average molar extinction coefficient for light rays with wavelengths from 190 nm to 380 nm, with respect to the M-OH bond / MO bond ratio of iron oxide particles obtained in Example 4 and Examples 4-2 to 4-4 of the present invention. [Figure 41] These are the reflection spectrum measurement results for iron oxide particles obtained in Example 4 and Examples 4-2 to 4-4 of the present invention, for light rays with wavelengths from 200 nm to 2500 nm. [Figure 42] This graph shows the average reflectance for light rays with wavelengths from 780 nm to 2500 nm against the M-OH bond / MO bond ratio of iron oxide particles obtained in Example 4 of the present invention and in Examples 4-2 to 4-4. [Figure 43] This is a TEM image of zinc oxide particles obtained in Example 5 of the present invention. [Figure 44] This is a TEM image of zinc oxide particles obtained in Example 5-4 of the present invention. [Figure 45] This shows the XRD measurement results of zinc oxide particles obtained in Example 5 of the present invention. [Figure 46]These are the IR measurement results for zinc oxide particles obtained in Example 5 and Example 5-4 of the present invention in the wavenumber range of 50 cm⁻¹ to 4000 cm⁻¹. [Figure 47] This shows the waveform separation results of IR measurements of zinc oxide particles obtained in Example 5 of the present invention in the wavenumber range of 100 cm⁻¹ to 1250 cm⁻¹. [Figure 48] This shows the waveform separation results of IR measurements of zinc oxide particles obtained in Example 5-2 of the present invention in the wavenumber range of 100 cm⁻¹ to 1250 cm⁻¹. [Figure 49] This shows the waveform separation results of IR measurements of zinc oxide particles obtained in Example 5-4 of the present invention in the wavenumber range of 100 cm⁻¹ to 1250 cm⁻¹. [Figure 50] This graph shows the molar extinction coefficients for dispersions obtained by dispersing zinc oxide particles obtained in Example 5, Examples 5-2 to 5-4, and Comparative Example 2-1 of the present invention in propylene glycol, with respect to measurement wavelengths from 200 nm to 780 nm. [Figure 51] These are the reflection spectrum measurement results for zinc oxide particles obtained in Example 5 and Examples 5-2 to 5-4 of the present invention, for light rays with wavelengths from 200 nm to 2500 nm. [Figure 52] This shows the transmission spectrum for light rays with wavelengths from 200 nm to 780 nm in a dispersion of zinc oxide particles obtained in Example 5 of the present invention and in Examples 5-2 to 5-4, dispersed in propylene glycol. [Figure 53] These are TEM images of zinc oxide particles obtained in Examples 5-6 of the present invention. [Figure 54] These are the IR measurement results for zinc oxide particles obtained in Example 5 and Example 5-6 of the present invention in the wavenumber range of 50 cm⁻¹ to 4000 cm⁻¹. [Figure 55] This graph shows the molar extinction coefficients for dispersions obtained by dispersing zinc oxide particles obtained in Examples 5 and 5-5 to 5-7 and Comparative Example 2-1 of the present invention in propylene glycol, with respect to measurement wavelengths from 200 nm to 780 nm. [Figure 56]These are the reflection spectrum measurement results for the zinc oxide particle powder obtained in Example 5 and Examples 5-5 to 5-7 of the present invention, for light rays with wavelengths from 200 nm to 2500 nm. [Figure 57] This graph shows the average reflectance for light rays with wavelengths from 780 nm to 2500 nm against the M-OH bond / MO bond ratio of zinc oxide particle powder obtained in Example 5 and Examples 5-5 to 5-7 of the present invention. [Figure 58] These are the reflectance spectra of the zinc oxide particle powder obtained in Example 5 and Examples 5-5 to 5-7 of the present invention for light rays with wavelengths from 200 nm to 780 nm. [Figure 59] This is a TEM image of zinc oxide particles obtained in Comparative Example 2-1 of the present invention. [Figure 60] This is a TEM image of zinc oxide particles obtained in Comparative Example 3-1 of the present invention. [Figure 61] This is a TEM image of zinc oxide particles obtained in Comparative Example 3-2 of the present invention. [Figure 62] This is the STEM mapping result of the cobalt-zinc composite oxide particles obtained in Example 9 of the present invention. [Figure 63] This is the line analysis result of the cobalt-zinc composite oxide particles obtained in Example 9 of the present invention. [Figure 64] This shows the STEM mapping results of the cobalt-zinc composite oxide particles obtained in Example 11 of the present invention. [Figure 65] This is the line analysis result of the cobalt-zinc composite oxide particles obtained in Example 11 of the present invention. [Figure 66] This is the transmission spectrum of a dispersion obtained by dispersing cobalt-zinc composite oxide particles obtained in Examples 9, 10, and 11 of the present invention in propylene glycol. [Figure 67] These are the reflectance spectra of cobalt-zinc composite oxide particles obtained in Examples 9 to 11 of the present invention. [Figure 68] This is the STEM mapping result of silicon-cobalt-zinc composite oxide particles obtained in Example 13 of the present invention. [Figure 69]This is the line analysis result of silicon-cobalt-zinc composite oxide particles obtained in Example 13 of the present invention. [Figure 70] These are the reflectance spectra of the cobalt-zinc composite oxide particles obtained in Examples 9 to 11 of the present invention, and the silicon-cobalt-zinc composite oxide particles obtained in Examples 12 to 14. [Modes for carrying out the invention]

[0044] Hereinafter, an example of an embodiment of the present invention will be described based on the drawings. However, the embodiments of the present invention are not limited to those described below.

[0045] (Oxide particles) The oxide particles according to the present invention are oxide particles in which the color characteristics of reflectance, transmittance, molar extinction coefficient, hue, or saturation are controlled by controlling the ratio of M-OH bonds or the M-OH bond / MO bond ratio contained in the oxide particles. When the oxide particles according to the present invention are used in a composition intended for application to coatings, painted bodies, human skin, etc., or in a film-like composition intended for use on glass, etc., it is possible not only to maintain the design, aesthetics, or texture but also to effectively develop color, thus providing an oxide composition for coating or in a film-like form that can be effectively used on the object to be coated.

[0046] (Morphology of oxide particles - 1) The oxide particles according to the present invention are oxide particles containing one or more different elements other than oxygen or hydrogen, obtained by methods such as reaction, crystallization, precipitation, and coprecipitation. The one or more different elements other than oxygen or hydrogen are preferably metallic elements or metalloid elements on the periodic table. The metalloid elements in the present invention are not particularly limited, but preferably include metalloid elements such as Si, Ge, As, Sb, Te, and Se. These metals and metalloids may be oxide particles consisting of a single element, composite oxide particles consisting of multiple elements, or composite oxide particles containing both metallic and metalloid elements. When implemented as oxide particles containing different elements, they can be implemented in the form of composite oxide particles, or, as described later, oxide particles in which at least a portion of the surface of the oxide particles is coated with an oxide containing an element different from the element other than oxygen contained in the oxide particles.

[0047] (Morphology of oxide particles - 2) The oxide particles according to the present invention are not limited to those composed solely of oxides. They can also be made to contain compounds other than oxides to an extent that does not affect the present invention. For example, oxide particles or composite oxide particles containing compounds other than oxides in addition to oxides, or oxide particles in which at least a part of the surface is coated with a compound other than oxide, can also be made. Examples of compounds other than oxides include hydroxides, hydroxide oxides, nitrides, carbides, various salts such as nitrates and sulfates, and hydrates and organic solvent hydrates.

[0048] (Morphology of oxide particles - 3) As an example of oxide particles of the present invention, iron oxide particles obtained in Examples 1-5 described later have at least a portion of their surface coated with silicon oxide, one of the silicon compounds. Figure 1 shows the STEM mapping results of the silicon oxide-coated iron oxide particles obtained in Examples 1-5. In Figure 1, (a) is a dark-field image (HAADF image), (b) is the mapping result for silicon (Si), (c) is for iron (Fe), and (d) is for oxygen (O). As can be seen in Figure 1, iron and oxygen are detected throughout the particle, and silicon is mainly detected on the surface of the particle. Figure 2 shows the line analysis results at the dashed lines in the HAADF image of Figure 1, and shows the atomic % (mol%) of the elements detected in the line portion from end to end of the particle. As can be seen in Figure 2, oxygen and silicon were detected at both ends of the analysis range in the line analysis, but iron was not detected up to a few nm inside from the end of the particle, indicating that the surface of the iron oxide is coated with silicon oxide. Figure 3 shows the STEM mapping results of the silicon oxide-coated iron oxide particles obtained in Example 1, which will be described later, and Figure 4 shows the line analysis results at the dashed lines in the HAADF image in Figure 3. As can be seen in Figures 3 and 4, the particles obtained in Example 1 differ from the particles obtained in Examples 1-5 in that the entire iron oxide particle is not covered with silicon oxide, but rather a part of the surface of the iron oxide particle is coated with silicon oxide, making them silicon oxide-coated iron oxide particles. Thus, as an example of the oxide of the present invention, silicon compound-coated oxide particles can be implemented in which at least a part of the surface of the oxide particle is coated with a silicon compound.

[0049] (Explanation of M-OH bond - 1) Figure 5 shows the FT-IR measurement results obtained by total internal reflection (ATR) of silicon compound coated oxide particles obtained in Example 1 and Examples 1-5 (hereinafter simply referred to as IR measurement). Here, IR is an abbreviation for infrared absorption spectroscopy. The IR measurement results of the silicon compound coated oxide particles obtained in Examples 1-5 were 1650 cm⁻¹ compared to the IR measurement results of the silicon compound coated oxide obtained in Example 1. -1 Nearby and 3400cm -1The broad peaks in the vicinity become smaller, reaching 800cm. -1 1250cm from the vicinity -1 The broad peaks in the vicinity appear to be shifted towards higher wavenumbers. In this invention, of these peaks, 3400 cm -1 The peaks in the vicinity are peaks derived from hydroxyl groups (-OH) containing water, at 800 cm. -1 1250cm from the vicinity -1 The peaks in the vicinity are thought to include peaks originating from M-OH bonds, and at 100 cm -1 From the vicinity, 800cm -1 The peaks in the vicinity are thought to include peaks originating from MO bonds. In this invention, various color characteristics are controlled by controlling the ratio of M-OH bonds or the M-OH bond / MO bond ratio contained in oxide particles. The ratio of M-OH bonds or the M-OH bond / MO bond ratio can be determined, for example, from the results of IR measurement. In addition, the ratio of M-OH bonds or the M-OH bond / MO bond ratio may be measured by methods other than IR measurement, such as X-ray photoelectron spectroscopy (XPS), solid-state nuclear magnetic resonance (solid-state NMR), and electron energy loss spectroscopy (EELS).

[0050] (Explanation of M-OH bond - 2) Wavenumber 100 cm in the above IR measurement results -1 From 1250cm -1 The waveform separation results for Example 1 are shown in Figure 6, and for Examples 1-5, in Figure 7. Note that in the previous explanation, the vertical axis of the IR measurement results was shown as transmittance (%T), but since the waveform separation was performed with absorbance on the vertical axis, the vertical axis in Figures 6 and 7 is shown as absorbance. In the present invention, the wavenumber 100 cm in the above IR measurement results... -1 From 1250cm -1 As a result of waveform separation, the peak was found to be at wavenumber 800 cm. -1 From 1250cm -1 Of the waveform-separated peaks, 936 cm² -1 A waveform-separated peak in the vicinity (Figure 6: M-OH bond 1) can be attributed to the peak originating from the M-OH bond, at wavenumber 100 cm. -1From 800cm -1 Of the waveform-separated peaks, 472 cm² -1 Nearby (Figure 6: MO bond 1) and 592 cm -1 The waveform-separated peaks in the vicinity (Figure 6: MO bond 2) can be attributed to peaks originating from the MO bond. In this invention, wavenumber 100 cm -1 From 1250cm -1 It is preferable to control the color characteristics of oxide particles by controlling the M-OH bond / MO bond ratio, which is the ratio of M-OH bonds to the total area of ​​each wave-separated peak in the region, controlling the area ratio of M-OH bonds to the M-OH bond to the MO bond to the MO bond to the MO bond to the M-OH bond to the MO bond ratio. Here, the assignment of each wave-separated peak to the M-OH bond or MO bond can be done from known literature or databases. Furthermore, when multiple peaks originating from MO bonds of the same type of M appear, it is preferable to use the peak with the largest area ratio of MO bond peaks to the total area of ​​each wave-separated peak, and similarly, when multiple peaks of M-OH bonds of the same type of M appear, it is preferable to use the peak with the largest area ratio of MO bond peaks to the total area of ​​each wave-separated peak to derive the M-OH bond / MO bond. Furthermore, if, for example, multiple peaks of MO bonds consisting of different types of M, such as Fe and Si, appear, or if multiple M-OH bonds consisting of different types of M appear, it is preferable to calculate the area ratio for each of the multiple different peaks for the M-OH bond or MO bond, and use the sum of these as the ratio of M-OH bonds or MO bonds to derive the M-OH bond / MO bond ratio. In the figure, peaks that cannot be assigned are treated as constituent peaks.

[0051] As can be seen in Figures 6 and 7, in Examples 1-5, the ratio of the total area of ​​each waveform-separated peak to the total peak component of the waveform-separated peaks is smaller for each waveform-separated peak compared to Example 1. In other words, it is shown that the ratio of M-OH bonds or the M-OH bond / MO bond ratio contained in the oxide particles of Examples 1-5 is lower than the ratio of M-OH bonds or the M-OH bond / MO bond ratio contained in the oxide particles of Example 1. In the present invention, as an example of calculating the ratio of M-OH bonds or the M-OH bond / MO bond ratio, the wavenumber 100 cm in the above IR measurement results... -1 From 1250cm -1 The peaks are waveform-separated, and the wavenumber 800 cm² is calculated relative to the total area of ​​all waveform-separated peaks. -1 From 1250cm -1 The area ratio (M-OH ratio [%]) calculated from the total area of ​​the M-OH bonds separated by waveform is defined as the ratio of M-OH bonds, at a wavenumber of 100 cm. -1 More than 800cm -1 The following is defined as the M-OH bond / MO bond ratio (M-OH bond / MO bond ratio [%]), which is the ratio of the above-mentioned M-OH bonds to the total area of ​​the wave-separated MO bonds. It has been found that the color characteristics of the oxide particles can be controlled by controlling these ratios.

[0052] (Explanation of M-OH bond - 4) Figure 8 shows the XRD measurement results of the oxide particles obtained in Examples 1-5. As can be seen in Figure 8, no peaks other than the peak originating from α-Fe2O3 are observed. Similarly, in Example 1, no peaks other than the peak originating from α-Fe2O3 were observed in the XRD measurement results (not shown), yet a peak originating from the M-OH bond was detected in the IR measurement results. This suggests that the M-OH bond is mainly present on the surface of the oxide particles rather than inside the particles, and therefore, peaks such as hydroxide were not detected in the XRD measurement results. Furthermore, the above XRD measurement results indicate that the silicon compound confirmed by the IR measurement contains amorphous material.

[0053] (Specific examples of M-OH bond ratios and color characteristics) Figure 9 shows the reflectance spectra of the oxide particles obtained in Examples 1 and 1-2 to 1-5 for light rays with wavelengths from 200 nm to 2500 nm. First, it can be seen that the reflectance for light rays in the near-infrared region with wavelengths from 780 nm to 2500 nm is higher for the silicon compound coated oxide particles obtained in Examples 1-5 than for the silicon compound coated oxide particles obtained in Example 1. In the above IR spectrum, at wavenumber 100 cm⁻¹ -1 From 1250cm -1 The M-OH ratio ([%]) and M-OH bond / MO bond ratio ([%]), calculated by waveform separation of peaks in the specified range, decrease in the order of Example 1-5 < 1-4 < 1-3 < 1-2 < 1, while the average reflectance for light rays with wavelengths from 780 nm to 2500 nm increases in the order of Example 1-5 > 1-4 > 1-3 > 1-2 > 1. Here, the average reflectance for light rays with wavelengths from 780 nm to 2500 nm refers to the simple average value of the reflectance for each measured wavelength in the wavelength range of 780 nm to 2500 nm. Figure 10 shows a graph of the average reflectance for light rays with wavelengths from 780 nm to 2500 nm in relation to the above M-OH bond / MO bond ratio. As can be seen in Figure 10, there was a tendency for the average reflectance for light rays with wavelengths from 780 nm to 2500 nm to be higher when the M-OH ratio and M-OH bond / MO bond ratio were lower. In other words, the oxide particles of the present invention are oxide particles in which the average reflectance to light rays with wavelengths from 780 nm to 2500 nm, which is one of the color characteristics, is controlled by controlling the ratio of M-OH bonds contained in the oxide particles. Furthermore, it is preferable that the oxide particles have an increased average reflectance to light rays with wavelengths from 780 nm to 2500 nm by lowering the ratio of M-OH bonds and the M-OH bond / MO bond ratio.

[0054] (Control of M-OH bond ratio and color characteristics) In this invention, similar to the reflectance and average reflectance for light rays in the near-infrared region, from 780 nm to 2500 nm, the ratio of M-OH bonds contained in oxide particles, M-OH bond / MO bond ratio, is controlled to obtain the molar extinction coefficient, average molar extinction coefficient, or transmittance for light rays in the ultraviolet region, from 190 nm (200 nm) to 380 nm, and the reflectance, average reflectance, transmittance, or average transmittance in the visible region, from 380 nm to 780 nm. * a * b * Hue H(=b) in a color system * / a * ) or saturation C(=√((a * ) 2 +(b * ) 2 The color characteristics such as )) can be precisely and rigorously controlled, and oxide particles that are particularly suitable for use in coatings or film-like compositions can be provided.

[0055] (Color characteristics: average molar extinction coefficient) The molar extinction coefficient can be calculated from the absorbance in ultraviolet-visible absorption spectroscopy and the molar concentration of the substance to be measured in the sample using the following formula 1. ε = A / (c·l) (Equation 1) Here, ε is a constant specific to the substance, called the molar extinction coefficient, and is the absorbance of a 1 mol / L dispersion with a thickness of 1 cm, so its unit is L / (mol·cm). A is the absorbance in the ultraviolet-visible absorption spectrum measurement, and c is the molar concentration of the sample (mol / L). l is the length through which light is transmitted (optical path length) (cm), which is usually the thickness of the cell used when measuring the ultraviolet-visible absorption spectrum. In this invention, in order to demonstrate the ability to absorb light in the ultraviolet region from wavelengths of 190 nm (200 nm) to 380 nm, the simple average of the molar extinction coefficients at each measurement wavelength in the measurement wavelength range from 190 nm (200 nm) to 380 nm was calculated and evaluated as the average molar extinction coefficient.

[0056] (Color characteristics: average reflectance or average transmittance) Furthermore, as shown above, the average reflectance for light rays with wavelengths from 780 nm to 2500 nm is the simple average of the reflectances at each measured wavelength in the reflection spectrum in the wavelength range from 780 nm to 2500 nm, and the average transmittance from 380 nm to 780 nm is the simple average of the transmittances at each measured wavelength in the transmission spectrum in the wavelength range from 380 nm to 780 nm.

[0057] These average molar extinction coefficients, average reflectances, and average transmittances are not limited to the wavelength ranges mentioned above, and the wavelength range to be averaged can be appropriately set according to the desired color characteristics.

[0058] (Color characteristics: Hue or saturation) In this invention, hue or saturation is L * a * b * Hue H(=b) in a color system * / a * , b * >0, a * >0), saturation C=√((a * ) 2 +(b * ) 2 This can be shown by ). Here, L * a * b * The color system is one of the uniform color spaces, L * This value represents brightness, and a larger number indicates greater brightness. Also, a * , b * L represents chromaticity. In this invention, the above color system is L * a * b * This method is not limited to a single color system. Color characteristics may be evaluated using other color systems such as the XYZ system.

[0059] (Controlling the ratio of M-OH bonds: Explanation of the method - 1) In the present invention, the method for controlling the ratio of M-OH bonds is not particularly limited, but it is preferable to control the ratio of M-OH bonds by modifying the functional groups contained in the oxide particles. The modification of functional groups can be performed by controlling the ratio of M-OH bonds by carrying out conventionally known reactions such as substitution reactions, addition reactions, elimination reactions, dehydration reactions, condensation reactions, reduction reactions, or oxidation reactions on the functional groups contained in the oxide particles. When controlling the ratio of M-OH bonds, the M-OH bond / MO bond ratio may be increased or decreased. As an example, a method can be used in which the ratio of M-OH bonds or the M-OH bond / MO bond ratio is controlled by esterification achieved by a dehydration-condensation reaction in which a carboxylic acid such as acetic anhydride is reacted with the M-OH bonds contained in the oxide particles, and an OH group is removed from the carboxyl group (-COOH) and a H group is removed from the hydroxyl group (-OH) in the M-OH group. In esterification, in addition to methods using acid anhydrides, methods using mixed acid anhydrides, acid halides, or dehydrating agents such as carbodiimide can also be used. In addition to the esterification described above, it is also possible to control the ratio of M-OH bonds or the ratio of M-OH bonds / Si-O bonds by methods such as reacting an alkyl halide, aryl halide, or heteroaryl halide with the M-OH group, preferably in the presence of an acid catalyst, to create an ether bond between the alkyl halide or other substance and M by dehydration, or by reacting an isocyanate or thioisocyanate with the M-OH group to create a (thio)urethane bond.

[0060] Regarding the substance that acts on the M-OH bond described above, the ratio of M-OH bonds or the M-OH bond / MO bond ratio in the oxide particles may be controlled by using a substance containing a fluorine-containing functional group or a hydrophilic or lipophilic functional group. In the present invention, it is not limited to creating new bonds by directly acting other substances or functional groups on the M-OH bond or MO bond. For example, it is also possible to control the ratio of M-OH bonds or the M-OH bond / MO bond ratio by acting a carbodiimide on a carboxylic acid contained in the particles, or by acting an ethylene oxide on the M-OH bond to create a bond such as MO-(CH2)2-OH, or by acting an epihalohydrin. In addition, the ratio of M-OH bonds or the M-OH bond / MO bond ratio can also be controlled by acting hydrogen peroxide or ozone on the oxide particles. Furthermore, when precipitating oxide particles in a liquid, it is possible to control the ratio of M-OH bonds or the M-OH bond / MO bond ratio by methods such as controlling the formulation used for precipitating the oxide particles or controlling the pH. Also, as an example of a dehydration reaction, the above ratio can be controlled by heat treatment of the oxide particles. When controlling the ratio of M-OH bonds or the M-OH bond / MO bond ratio by heat treatment of oxide particles, it can be carried out by dry heat treatment or by heat treatment in the state of a dispersion in which the oxide particles are dispersed in a dispersion medium. In addition, as will be described later, the above ratio can be controlled by dispersing oxide particles in a target solvent, adding a substance containing functional groups to the dispersion and performing treatment such as stirring, or by performing treatment such as stirring in the dispersion containing the precipitated oxide particles. Furthermore, it can also be carried out by constructing a device in which a dispersion device and a filtration membrane are connected, and removing impurities from a slurry containing oxide particles by dispersion treatment of particles and treatment by cross-flow membrane filtration, etc., by changing the slurry temperature or the temperature of the washing solution used in cross-flow.In this case, since a uniform modification treatment can be applied to the primary particles of the oxide particles, particularly the surface of each primary particle, there is an advantage in that the control of the ratio of M-OH bonds contained in the oxide particles and the control of color characteristics can be performed more precisely and uniformly in the present invention.

[0061] The pH adjustment when precipitating the oxide particles may be adjusted by including a pH adjusting agent such as an acidic or basic substance in at least one of the various solutions or solvents in the present invention, or by changing the flow rate when mixing the fluid containing the oxide raw material solution and the fluid containing the oxide precipitation solvent.

[0062] The method for changing the functional groups contained in the oxide particles according to the present invention is not particularly limited. It may be carried out by dispersing the oxide particles in a target solvent, adding a substance containing functional groups to the dispersion and subjecting it to treatment such as stirring, or by mixing a fluid containing oxide particles and a fluid containing a substance containing functional groups using the microreactor described above.

[0063] The substances containing functional groups are not particularly limited, but include substances containing functional groups that can substitute for hydroxyl groups contained in oxide particles, such as acylating agents like acetic anhydride and propionic anhydride; methylating agents like dimethyl sulfate and dimethyl carbonate; and silane coupling agents like chlorotrimethylsilane and methyltrimethoxysilane.

[0064] As described above, the ratio of M-OH bonds can also be controlled by reacting the oxide particles with hydrogen peroxide or ozone. The method of reacting the oxide particles with hydrogen peroxide or ozone is not particularly limited. The oxide particles may be dispersed in a target solvent, and a solution such as hydrogen peroxide or ozone or an aqueous solution containing them may be added to the dispersion and subjected to stirring or other treatments. Alternatively, the method may be carried out by mixing a fluid containing oxide particles with a fluid containing hydrogen peroxide or ozone using the microreactor described above.

[0065] The above-mentioned dispersion can be implemented as a liquid dispersion in which oxide particles are dispersed in a liquid dispersion medium such as water, an organic solvent, or a resin, or as a dispersion in the form of a coating film prepared using a dispersion containing oxide particles. When heat treatment is performed on the dispersion containing oxide particles, particle aggregation can be suppressed compared to dry heat treatment. Furthermore, when the oxide particles of the present invention are used in the laminated coating film and high-design multi-layer coating film described in Japanese Patent Publication No. 2014-042891 and Japanese Patent Publication No. 2014-042892, for example, the color characteristics of the oxide particles can be controlled by controlling the M-OH bond / MO bond ratio contained in the oxide particles by heat treatment or other methods after the oxide particles have been formed into the laminated coating film or multi-layer coating film. This is suitable for reducing the number of processes and for precise control of color characteristics. Furthermore, in the laminated coating films and high-design multi-layer coating films described in Japanese Patent Publication No. 2014-042891 and Japanese Patent Publication No. 2014-042892, by increasing the difference between highlights and shades for a specific color, the intensity of reflected light changes significantly depending on the observation angle, thereby achieving a sense of depth and detail. For this reason, it is required to improve the transmittance for a specific color and to increase the difference between highlights and shades in order to enhance the highlights. In particular, for coating films containing substances having ultraviolet shielding properties and near-infrared reflection properties such as oxides, such as clear coating films, the greater the molar extinction coefficient in the ultraviolet region, which is the ability of oxide particles to absorb ultraviolet light, the more transparent the coating film as an oxide particle dispersion can be, and the less oxide particles are used, the smaller the haze value can be.

[0066] In addition to the above-mentioned laminated coating applications, it can also be suitably used as a composition for transparent materials by dispersing oxide particles such as silicon compound-coated zinc oxide particles in transparent materials such as glass or transparent resins. This composition can be used for purposes such as absorbing ultraviolet rays and reflecting near-infrared rays, and can further enhance the transmission characteristics for visible light, making it suitable for use as a composition for transparent materials for ultraviolet and near-infrared protection. Furthermore, similar to the above-mentioned laminated coatings, it is possible to control the color characteristics of oxide particles by dispersing oxide particles in glass or transparent resins to form a film or transparent material, and then performing functional group modification treatments such as heat treatment to control the ratio of M-OH bonds contained in the oxide particles. This is suitable for reducing the number of processes and for precise control of color characteristics, similar to the above-mentioned laminated coatings.

[0067] (Preferred form of oxide particles - 1) In the present invention, the primary particle diameter of the oxide particles is preferably 1 nm or more and 100 nm or less, and more preferably 1 nm or more and 50 nm or less. As described above, since the ratio of M-OH bonds contained in oxide particles is assumed to be mainly present on the surface of the particles, oxide particles with a primary particle diameter of 100 nm or less have a larger surface area compared to oxide particles with a primary particle diameter exceeding 100 nm, and it is thought that controlling the ratio of M-OH bonds or the M-OH bond / MO bond ratio of the oxide particles has a significant effect on the color characteristics of the oxide particles, such as transmission characteristics, absorption characteristics, reflection characteristics, hue, or saturation. For this reason, oxide particles with a primary particle diameter of 100 nm or less have the advantage that predetermined color characteristics (especially color characteristics suitable for use as a coating or film) can be suitably exhibited by controlling the ratio of M-OH bonds or the M-OH bond / MO bond ratio contained in the oxide particles.

[0068] (Preferred form of oxide particles - 2) In the present invention, when oxide particles are oxide particles in which at least a part of the surface of the particles is coated, such as the silicon compound-coated iron oxide particles described above, it is preferable that the ratio of the average primary particle diameter of the oxide particles after coating with the compound to the average primary particle diameter of the oxide particles before coating is 100.5% or more and 190% or less. If the coating of the compound on the oxide particles is too thin, the effects related to the color characteristics of the oxide particles coated with the compound may not be able to be exhibited. Therefore, it is preferable that the average primary particle diameter of the oxide particles after coating with the compound is 100.5% or more of the average primary particle diameter of the oxide particles. If the coating is too thick or if coarse aggregates are coated, it becomes difficult to control the color characteristics. Therefore, it is preferable that the average primary particle diameter of the oxide particles after coating with the compound is 190% or less of the average primary particle diameter of the oxide particles. The oxide particles coated with the compound according to the present invention may also be core-shell type compound-coated oxide particles in which the entire surface of a core oxide particle is uniformly coated with the compound. Furthermore, while it is preferable that the compound-coated oxide particles are compound-coated oxide particles in which at least a portion of the surface of a single oxide particle is coated with the compound, rather than multiple oxide particles being aggregated, compound-coated oxide particles in which at least a portion of the surface of an aggregate formed by multiple oxide particles being aggregated is coated with the compound.

[0069] (Preferred form of oxide particles - 3) The compound coating at least a portion of the oxide surface in the present invention is preferably a silicon compound, more preferably a silicon oxide, and even more preferably an amorphous silicon oxide. By including amorphous silicon oxide in the silicon compound, it is possible to precisely control the color characteristics of the silicon compound-coated oxide particles, such as reflectance, transmittance, molar extinction coefficient, hue, and saturation. If the silicon compound is a crystalline silicon oxide, it becomes extremely difficult to create M-OH(Si-OH), which may make it difficult to control the color characteristics in the present invention.

[0070] (Method for manufacturing oxide particles: apparatus) Examples of methods for producing oxide particles according to the present invention include, for example, producing oxide particles using a microreactor, performing a reaction in a dilute system in a batch container, or using a grinding method such as a bead mill, and controlling the ratio of M-OH bonds contained in the oxide particles in a reaction vessel, either simultaneously with or after production. Alternatively, apparatus and methods such as those described in Japanese Patent Application Publication No. 2009-112892, proposed by the applicant, may be used to produce oxide particles or to control the ratio of M-OH bonds in the oxide particles. The apparatus described in Japanese Patent Publication No. 2009-112892 comprises a stirring tank having an inner surface with a circular cross-sectional shape, and a stirring tool attached to the inner surface of the stirring tank with a small gap between them. The stirring tank is provided with at least two fluid inlets and at least one fluid outlet. From one of the fluid inlets, a first fluid to be treated containing one of the reactants is introduced into the stirring tank. From the other fluid inlet, a second fluid to be treated containing one reactant different from the first fluid to be treated is introduced into the stirring tank from a different flow path than that of the first fluid to be treated. At least one of the stirring tank and the stirring tool rotates at high speed relative to the other, causing the fluid to be treated to become a thin film, and reactants contained in at least the first fluid to be treated and the second fluid to be treated react with each other within this thin film. It is also stated that, in order to introduce three or more fluids to be treated into the stirring tank, three or more introduction pipes may be provided as shown in Figures 4 and 5 of the same publication. Another example of the above-mentioned microreactor is a device that operates on the same principle as the fluid processing apparatus described in Patent Documents 6 and 7.

[0071] As an example of a method for producing oxide particles according to the present invention, it is preferable to use a method in which an oxide raw material solution containing at least an oxide particle raw material and an oxide precipitation solvent containing at least an oxide precipitation substance for precipitating oxide particles are prepared, and oxide particles are produced in a mixed fluid obtained by mixing the oxide raw material solution and the oxide precipitation solvent by methods such as reaction, crystallization, precipitation, and coprecipitation. As described above, when producing oxide particles by methods such as reaction, crystallization, precipitation, and coprecipitation, it is also possible to produce particles in which the ratio of M-OH bonds is controlled to a predetermined value.

[0072] The raw materials for the oxide particles in this invention are not particularly limited. Any material that can be converted into an oxide by methods such as reaction, crystallization, precipitation, or coprecipitation can be used. Examples include elemental metals or metalloids, or compounds thereof. In this invention, the above-mentioned compounds of metals or metalloids are collectively referred to as compounds. While the compounds are not particularly limited, examples include salts or oxides, hydroxides, hydroxide oxides, nitrides, carbides, complexes, organic salts, organic complexes, organic compounds, or their hydrates, organic solvent dihydrates, etc. Examples of salts of metals or metalloids are not particularly limited, but include nitrates, nitrites, sulfates, sulfites, formates, acetates, phosphates, phosphites, hypophosphites, chlorides, oxysalts, acetylacetonates, or their hydrates, organic solvent dihydrates, etc. Examples of organic compounds include alkoxides of metals or metalloids. These metal or metalloid compounds may be used individually or as a mixture of several or more.

[0073] Furthermore, in the case of oxide particles containing silicon compounds, such as silicon compound-coated oxides, the raw materials for the silicon compound include silicon oxides and hydroxides, other silicon salts and alkoxides, and hydrates thereof. While not particularly limited, examples include silicates such as sodium silicate, phenyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-trifluoropropyl-trimethoxysilane, methacryloxypropyltriethoxysilane, tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), and oligomer condensates of TEOS, such as ethyl silicate 40, tetraisopropylsilane, tetrapropoxysilane, tetraisobutoxysilane, tetrabutoxysilane, and similar substances. Furthermore, other siloxane compounds, bis(triethoxysilyl)methane, 1,9-bis(triethoxysilyl)nonane, diethoxydichlorosilane, triethoxychlorosilane, etc. may be used as raw materials for the silicon compound. When the oxide particles in the present invention are silicon compound-coated oxide particles, it is preferable that silicon is present in an amount of 2% to 80% of the elements other than oxygen that constitute the coated oxide particles, and more preferably 5% to 50%. The above silicon compound raw materials can be used by selecting the appropriate amount and type depending on the type of oxide particles to be used.

[0074] Furthermore, if the raw material for the oxide particles or silicon compound is a solid, it is preferable to use the oxide particle raw material in a molten state, or in a state mixed or dissolved in a solvent described later (including a molecularly dispersed state). Even if the raw material for the oxide particles is a liquid or gas, it is preferable to use it in a state mixed or dissolved in a solvent described later (including a molecularly dispersed state).

[0075] The oxide precipitate material is not particularly limited as long as it is a material that can precipitate the oxide particles contained in the oxide raw material solution as oxide particles, for example, an acidic substance or a basic substance can be used. At least it is preferable to use the oxide precipitate material in a state in which it is mixed, dissolved, or molecularly dispersed in the solvent described later.

[0076] Basic substances include metal hydroxides such as sodium hydroxide and potassium hydroxide, metal alkoxides such as sodium methoxide and sodium isopropoxide, amine compounds such as triethylamine, diethylaminoethanol and diethylamine, and ammonia.

[0077] Examples of acidic substances include inorganic acids such as aqua regia, hydrochloric acid, nitric acid, fuming nitric acid, sulfuric acid, and fuming sulfuric acid, as well as organic acids such as formic acid, acetic acid, chloroacetic acid, dichloroacetic acid, oxalic acid, trifluoroacetic acid, trichloroacetic acid, and citric acid. The above basic and acidic substances can be used to precipitate oxide particles, and as described above, they can also be used as pH adjusters to control the ratio of M-OH bonds contained in the oxide particles.

[0078] (solvent) Examples of solvents used in oxide raw material solutions and oxide precipitation solvents include water, organic solvents, or mixed solvents consisting of several of these. Examples of water include tap water, deionized water, pure water, ultrapure water, RO water (reverse osmosis water), etc. Examples of organic solvents include alcohol compound solvents, amide compound solvents, ketone compound solvents, ether compound solvents, aromatic compound solvents, carbon disulfide, aliphatic compound solvents, nitrile compound solvents, sulfoxide compound solvents, halogen compound solvents, ester compound solvents, ionic liquids, carboxylic acid compounds, sulfonic acid compounds, etc. Each of the above solvents may be used individually or in combination. Examples of alcohol compound solvents include monohydric alcohols such as methanol and ethanol, and polyols such as ethylene glycol and propylene glycol.

[0079] (Dispersants, etc.) In the present invention, various dispersants and surfactants may be used as needed and for the purpose, as long as they do not adversely affect the production of oxide particles. While not particularly limited, various commercially available products, products, or newly synthesized dispersants can be used. Examples include anionic surfactants, cationic surfactants, nonionic surfactants, and dispersants such as various polymers. These may be used individually or in combination of two or more. The above-mentioned surfactants and dispersants may be contained in at least one of the oxide raw material solution and oxide precipitation solvent. Furthermore, the above-mentioned surfactants and dispersants may be contained in a fluid different from both the oxide raw material solution and the oxide precipitation solvent.

[0080] (Controlling the ratio of M-OH bonds: Method overview) In the present invention, as described above, the ratio of M-OH bonds, which are bonds between a single or multiple elements (M) other than oxygen or hydrogen contained in the oxide particles and a hydroxyl group (OH), is controlled. Specifically, the method can be carried out by dividing it into two steps: preparing untreated oxide particles having a predetermined primary particle size to which the ratio of M-OH bonds or the M-OH bond / MO bond ratio to be controlled; and applying a treatment to the untreated oxide particles to control the ratio of M-OH bonds or the M-OH bond / MO bond ratio. However, in the step of preparing untreated oxide particles, when manufacturing oxide particles by precipitation or the like, particles in which the ratio of M-OH bonds or the M-OH bond / MO bond ratio is controlled to a predetermined value may be manufactured.

[0081] (Composition for coating or film-like composition) The oxide composition for coating or film-like oxide composition of the present invention is not particularly limited to those described in Japanese Patent Publication No. 2014-042891 and Japanese Patent Publication No. 2014-042892, and can be applied to various coating or film-like compositions for the purpose of painting, such as solvent-based paints and water-based paints. The oxide composition for coating may further contain, as appropriate and depending on the purpose, additives such as pigments, dyes, wetting agents, dispersants, color separation inhibitors, leveling agents, viscosity modifiers, anti-skinning agents, anti-gelling agents, defoaming agents, thickeners, anti-sagging agents, antifungal agents, ultraviolet absorbers, film-forming aids, surfactants, and resin components, in addition to pigments and dyes. Examples of resin components for the purpose of painting include polyester resins, melamine resins, phenolic resins, epoxy resins, vinyl chloride resins, acrylic resins, urethane resins, silicone resins, and fluororesins. The coating to which the coating oxide composition of the present invention is applied may be a single-layer coating composed of a single coating composition, or a multi-layer coating composed of multiple coating compositions, as in the laminated coating applications described in Japanese Patent Application Publication Nos. 2014-042891 and 2014-042892. It can also be implemented by incorporating it into a coating containing a pigment, or by incorporating it into a coating such as a clear coating. When the above-mentioned film-like composition is intended, it may optionally contain a binder resin, a curing agent, a curing catalyst, a leveling agent, a surfactant, a silane coupling agent, an antifoaming agent, a coloring agent such as a pigment or dye, an antioxidant, etc.

[0082] (Compositions for coating, film-like compositions, or compositions for transparent materials) The oxide composition for coating, the oxide composition in the form of a film, or the composition for transparent materials according to the present invention contains oxide particles such as powder of oxide particles; dispersions in which oxide particles are dispersed in a liquid dispersion medium; and dispersions in which oxide particles are dispersed in a solid (or liquid before solidification, etc.) such as glass or transparent resin. The oxide particles contained in the oxide composition for coating or the oxide composition in the form of a film may consist of a single oxide particle, an aggregate formed by the aggregation of multiple oxide particles, or a mixture of both. When composed of an aggregate formed by the aggregation of multiple oxide particles, it is preferable that the size of the aggregate is 50 nm or less. Furthermore, the oxide composition may be dispersed in cosmetics or paints together with various pigments, or used as an overcoat on a coating film. In addition, oxide particles can also be used as a single pigment. Examples of liquid dispersion media include water such as tap water, distilled water, RO water (reverse osmosis water), pure water, and ultrapure water; alcohol-based solvents such as methanol, ethanol, and isopropyl alcohol; polyhydric alcohol-based solvents such as propylene glycol, ethylene glycol, diethylene glycol, and glycerin; ester-based solvents such as ethyl acetate and butyl acetate; aromatic solvents such as benzene, toluene, and xylene; ketone-based solvents such as acetone and methyl ethyl ketone; nitrile-based solvents such as acetonitrile; and silicone oils, vegetable oils, and waxes. These may be used individually or in combination.

[0083] (Color of coating composition or film composition) The color of the coating, film, or transparent material such as glass is not particularly limited, and the oxide composition or film-like composition for coating of the present invention can be used for any desired hue. It can be suitably formulated for coatings of white, gray, black, for example, colors ranging from white with a lightness of 10 to black with a lightness of 0 in the Munsell color system, red, for example, colors ranging from RP to YR in the Munsell color circle, yellow to green, for example, colors ranging from Y to BG in the Munsell color circle, or blue to purple, for example, colors ranging from B to P in the Munsell color circle (each including metallic colors), but is not limited to these, and other hues may also be used. In particular, using the coating composition containing the oxide particles of the present invention as a topcoat for coating films or painted bodies exhibiting these colors is suitable because it can significantly reduce the impairment of the color development of each color, thereby improving the design of the painted body. The pigments and dyes included in the coating composition as needed can be a variety of pigments and dyes, and for example, all pigments and dyes registered in the color index can be used. Among these, for example, pigments that make up green are those classified as CIPigment Green; pigments that make up blue are those classified as CIPigment Blue; pigments that make up white are those classified as CIPigment White; pigments that make up yellow are those classified as CIPigment Yellow; pigments and dyes that make up red are those classified as CIPigment Red in the color index; and pigments and dyes that make up purple are those classified as CIPigment Violet or CIPigment Orange, etc.More specifically, examples include quinalidone pigments such as CIPigment Red 122 and CIPigment Violet 19, diketopyrrolopyrrole pigments such as CIPigment Red 254 and CIPigment Orange 73, naphthol pigments such as CIPigment Red 150 and CIPigment Red 170, perylene pigments such as CIPigment Red 123 and CIPigment Red 179, and azo pigments such as CIPigment Red 144. These pigments and dyes may be used individually or in combination. The oxide composition of the present invention can also be incorporated into coating or film compositions on its own, without being mixed with the above pigments and dyes. By including the oxide particles in the coating composition according to the present invention, it is possible to create a coating with higher saturation, and a large difference between highlights and shades when used in laminated coating, for example, as described in Japanese Patent Publication No. 2014-042891 and Japanese Patent Publication No. 2014-042892, thereby preventing white blurring in the shades, increasing the degree of blackness, and obtaining a sharp metallic texture, which is therefore preferable. Furthermore, by including the oxide particles in a film-like composition for use on transparent substrates such as glass used in buildings, vehicles, displays, etc., it is possible to enhance safety for the human body by effectively absorbing ultraviolet rays and shielding them, suppress the decomposition of organic matter in buildings and vehicles, and effectively reflect near-infrared rays and shielding them, thereby suppressing the rise in temperature inside buildings and vehicles, and furthermore, it is possible to create a highly transparent film or glass that exhibits high transmittance characteristics for visible light, which is therefore preferable. [Examples]

[0084] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, pure water with a conductivity of 0.86 μS / cm (measurement temperature: 25°C) was used.

[0085] (Preparation of samples for TEM observation and preparation of samples for STEM observation) A portion of the wet cake sample of oxide particles obtained in the examples was dispersed in propylene glycol and further diluted 100-fold with isopropyl alcohol (IPA). The resulting dilution was dropped onto a collodion membrane or microgrid and dried to obtain a sample for TEM or STEM observation.

[0086] (Transmission electron microscope and energy-dispersive X-ray spectrometer: TEM-EDS analysis) For observation and quantitative analysis of oxide particles using TEM-EDS analysis, a transmission electron microscope, JEM-2100 (manufactured by JEOL Ltd.), equipped with an energy-dispersive X-ray spectrometer, JED-2300 (manufactured by JEOL Ltd.), was used. Observation conditions included an acceleration voltage of 80 kV and an observation magnification of 25,000x or higher. Particle diameter was calculated from the distance between the maximum outer circumferences of oxide particles observed by TEM, and the average value (average primary particle diameter) was calculated from the results of particle diameter measurements for 100 particles. The molar ratio of the elemental components constituting the oxide in the oxide particles was calculated using TEM-EDS, and the average value of the molar ratios calculated for 10 or more particles was calculated.

[0087] (Scanning transmission electron microscope and energy-dispersive X-ray spectrometer: STEM-EDS analysis) For the mapping and quantification of elements contained in oxide particles using STEM-EDS analysis, an atomic-resolution analytical electron microscope, JEM-ARM200F (manufactured by JEOL Ltd.), equipped with an energy-dispersive X-ray spectrometer, Centurio (manufactured by JEOL Ltd.), was used. The observation conditions were an acceleration voltage of 80 kV, an observation magnification of 50,000x or more, and an analysis was performed using a beam diameter of 0.2 nm.

[0088] (X-ray diffraction measurement) For X-ray diffraction (XRD) measurements, a powder X-ray diffraction analyzer EMPYREAN (manufactured by PANalytical Division, Spectris Corporation) was used. The measurement conditions were: measurement range: 10 to 100 [°2Theta] Cu versus cathode, tube voltage 45kV, tube current 40mA, and scanning speed 0.3° / min. XRD measurements were performed using the dried oxide powder obtained in each example.

[0089] (FT-IR measurement) For FT-IR measurements, a Fourier transform infrared spectrophotometer, FT / IR-6600 (manufactured by JASCO Corporation), was used. The measurement conditions were the ATR method under a nitrogen atmosphere, with a resolution of 4.0 cm. -1 The cumulative number of measurements is 1024. The infrared absorption spectrum is measured at wavenumber 100 cm. -1 From 1250cm -1 The waveform separation of the peaks was performed by curve fitting using the spectral analysis program included with the FT / IR-6600 control software, so that the sum of squared residuals was 0.01 or less. The measurements were taken using the dried oxide powder obtained in the examples.

[0090] (Transmission spectrum, absorption spectrum, reflectance spectrum, hue, and saturation) Transmission spectra, absorption spectra, reflectance spectra, hue, and chroma were measured using a UV-Vis-Near Infrared spectrophotometer (product name: V-770, manufactured by JASCO Corporation). The measurement range for transmission spectra was 190 nm to 800 nm or 200 nm to 800 nm, and the measurement range for absorption spectra was also 190 nm to 800 nm or 200 nm to 800 nm, with a sampling rate of 0.2 nm and a slow measurement speed. For specific wavelength ranges, the transmittance at multiple measurement wavelengths was simply averaged to obtain the average transmittance. The molar absorption coefficient was calculated from the absorbance obtained from the measurement results and the oxide concentration of the dispersion liquid after measuring the absorption spectrum, and a graph was made with the measurement wavelength on the horizontal axis and the molar absorption coefficient on the vertical axis. A liquid cell with a thickness of 1 cm was used for the measurement. Also, the molar absorption coefficients at a plurality of measurement wavelengths from 190 nm (200 nm) to 380 nm were simply averaged to calculate the average molar absorption coefficient.

[0091] The reflection spectrum was measured with a measurement range from 200 nm to 2500 nm, a sampling rate of 2.0 nm, a medium measurement speed, and a double-beam photometry method, and total reflection measurement was performed to measure regular reflection and diffuse reflection. Also, for the background measurement (baseline setting) when measuring the powder, a standard white plate (product name: Spectralon (trademark), manufactured by Labsphere) was used. The reflection spectrum was measured using the dried powder of the silicon compound-coated iron oxide particles obtained in each example. For a specific wavelength region, the reflectances at a plurality of measurement wavelengths were simply averaged to obtain the average reflectance. The hue and chroma were measured from the reflection spectrum measurement results using the L * a * b * color system, a visual field of 2 (deg), a light source of D65-2, an equal-color function of JIS Z 8701:1999, and a data interval of 5 nm. The obtained L * , a * , b * From each value, the hue H = b * / a * , and the chroma C = √((a * ) 2 +(b * ) 2 ) was calculated using the formula.

[0092] (Example 1) In Example 1, we will describe silicon compound-coated iron oxide particles, in which at least a portion of the surface of iron oxide particles is coated with a silicon compound. Using a high-speed rotary dispersion emulsifier called Creamix (product name: CLM-2.2S, manufactured by M-Technique Co., Ltd.), an oxide raw material solution (solution A), an oxide precipitation solvent (solution B), and a silicon compound raw material solution (solution C) were prepared. Specifically, based on the oxide raw material solution formulation shown in Example 1 in Table 1, each component of the oxide raw material solution was homogeneously mixed using Creamix by stirring at a preparation temperature of 40°C and a rotor rotation speed of 20,000 rpm for 30 minutes to prepare the oxide raw material solution. Similarly, based on the oxide precipitation solvent formulation shown in Example 1 in Table 1, each component of the oxide precipitation solvent was homogeneously mixed using Creamix by stirring at a preparation temperature of 45°C and a rotor rotation speed of 15,000 rpm for 30 minutes to prepare the oxide precipitation solvent. Furthermore, based on the silicon compound raw material solution formulation shown in Example 1 of Table 1, each component of the silicon compound raw material solution was homogeneously mixed using a Creamix at a preparation temperature of 20°C and a rotor rotation speed of 6000 rpm for 10 minutes to prepare the silicon compound raw material solution. For the substances indicated by the chemical formulas and abbreviations listed in Table 1, 97wt% H2SO4 was concentrated sulfuric acid (manufactured by Kishida Chemical Co., Ltd.), NaOH was sodium hydroxide (manufactured by Kanto Chemical Co., Ltd.), TEOS was tetraethyl orthosilicate (manufactured by Wako Pure Chemical Industries, Ltd.), and Fe(NO3)3·9H2O was iron nitrate nonahydrate (manufactured by Kanto Chemical Co., Ltd.).

[0093] Next, the prepared oxide raw material solution, oxide precipitation solvent, and silicon compound raw material solution were mixed using a fluid processing apparatus described in Patent Document 7 by the applicant. Here, the fluid processing apparatus described in Patent Document 7 is the apparatus shown in Figure 1(B) of the said publication, in which the openings d20 and d30 of the second and third introduction parts are formed in a ring shape, and the openings in the central part of the processing surface 2 are concentric rings surrounding the central opening. Specifically, the oxide raw material solution was introduced as solution A from the first introduction part d1 between the processing surfaces 1 and 2, and while the processing unit 10 was operated at a rotation speed of 1130 rpm, the oxide precipitation solvent was introduced as solution B from the second introduction part d2 between the processing surfaces 1 and 2, and the oxide raw material and oxide precipitation solvent were mixed in a thin film fluid, causing core iron oxide particles to precipitate between the processing surfaces 1 and 2. Next, the silicon compound raw material solution was introduced as solution C from the third introduction part d3 between the processing surfaces 1 and 2 and mixed with the mixed fluid containing the core iron oxide particles in the thin film fluid. A silicon compound was deposited on the surface of the core iron oxide particles, and the discharge liquid containing the silicon compound-coated iron oxide particles (hereinafter referred to as the silicon compound-coated iron oxide particle dispersion) was discharged from between the processing surfaces 1 and 2 of the fluid processing apparatus. The discharged silicon compound-coated iron oxide particle dispersion was collected in beaker b via vessel v.

[0094] Table 2 shows the operating conditions of the fluid processing apparatus, the average primary particle size calculated from TEM observation results of the obtained silicon compound-coated iron oxide particles, and the Si / Fe molar ratio calculated from TEM-EDS analysis, along with the calculated values ​​from the formulations and introduction flow rates of solutions A, B, and C. The introduction temperature (supply temperature) and introduction pressure (supply pressure) of solutions A, B, and C shown in Table 2 were measured using thermometers and pressure gauges installed in the sealed introduction passages (first introduction section d1, second introduction section d2, and third introduction section d3) leading between processing surfaces 1 and 2. The introduction temperature of solution A shown in Table 2 is the actual temperature of solution A under the introduction pressure in the first introduction section d1, the introduction temperature of solution B is the actual temperature of solution B under the introduction pressure in the second introduction section d2, and the introduction temperature of solution C is the actual temperature of solution C under the introduction pressure in the third introduction section d3.

[0095] A pH meter, model D-51, manufactured by Horiba, Ltd., was used for pH measurement. The pH of solutions A, B, and C was measured at room temperature before introducing them into the fluid processing device. Furthermore, since it is difficult to measure the pH of the mixed fluid immediately after mixing the oxide raw material solution and the oxide precipitation solvent, and the pH of the fluid containing the core iron oxide particles immediately after mixing the silicon compound raw material solution, the pH of the silicon compound-coated iron oxide particle dispersion, which was discharged from the device and collected in beaker b, was measured at room temperature.

[0096] Dry powder and wet cake samples were prepared from a dispersion of silicon compound-coated iron oxide particles discharged from a fluid processing device and collected in beaker b. The preparation method followed the standard procedure for this type of processing: the discharged dispersion of silicon compound-coated iron oxide particles was collected, the silicon compound-coated iron oxide particles were allowed to settle, and the supernatant was removed. Then, washing and settling with 100 parts by weight of pure water was repeated three times, and the silicon compound-coated iron oxide particles were washed three more times. Finally, a portion of the resulting wet cake of silicon compound-coated iron oxide particles was dried at -0.10 MPaG at 25°C for 20 hours to obtain dry powder. The remainder was used as the wet cake sample.

[0097] [Table 1]

[0098] [Table 2]

[0099] Figure 3 shows the STEM mapping results of the silicon compound-coated iron oxide particles obtained in Example 1, and Figure 4 shows the line analysis results at the dashed lines in the HAADF image in Figure 3. As can be seen in Figures 3 and 4, among the silicon compound-coated iron oxide particles obtained in Example 1, some particles were not entirely covered with the silicon compound, and silicon compound-coated iron oxide particles were observed in which only a portion of the surface of the iron oxide particle was coated with the silicon compound.

[0100] The silicon compound-coated iron oxide particles obtained in Example 1 were subjected to a dehydration reaction by heat treatment using an electric furnace as a treatment to modify the functional groups contained in the silicon compound-coated iron oxide particles. The heat treatment conditions were as follows: Example 1: untreated, Example 1-2: 200°C, Example 1-3: 400°C, Example 1-4: 600°C, Example 1-5: 800°C, and the heat treatment time was 30 minutes at each heat treatment temperature. Figure 1 shows the STEM mapping results of the silicon compound-coated iron oxide obtained in Examples 1-5, and Figure 2 shows the line analysis results at the dashed lines in the HAADF image in Figure 1. As can be seen in Figures 1 and 2, the silicon compound-coated iron oxide particles obtained in Examples 1-5 were observed as iron oxide particles with the entire particle covered by the silicon compound.

[0101] Figure 5 shows the IR measurement results of silicon compound-coated iron oxide particles obtained in Example 1 and Examples 1-5, measured by the ATR method. The IR measurement results of the silicon compound-coated oxide particles obtained in Examples 1-5 were 1650 cm² higher than the IR measurement results of the silicon compound-coated oxide obtained in Example 1. -1 Nearby and 3400cm -1 The broad peaks in the vicinity become smaller, reaching 800cm. -1 1250cm from the vicinity -1 The broad peak in the vicinity appears to be shifting towards higher wavenumbers.

[0102] Wavenumber 100 cm² in the IR measurement results of Example 1 or Example 1-5 described above -1 From 1250cm -1The results of waveform separation of the peaks are shown in Figure 6 for Example 1 and in Figure 7 for Examples 1-5. As can be seen in Figures 6 and 7, Examples 1-5 have a smaller M-OH bond / MO bond ratio compared to Example 1. This is the ratio of the total area of ​​each waveform-separated peak to the total area of ​​each waveform-separated peak to the ratio of the total area of ​​each waveform-separated peak to the MO bond in all peak components of the waveform-separated peaks. In other words, the M-OH bond / MO bond ratio in the oxide particles of Example 1-5 is lower than that of the oxide particles of Example 1. Furthermore, in the IR measurement results of the silicon compound-coated iron oxide particles mentioned above (Figure 5), at 800 cm² -1 1250cm from the vicinity -1 The reason why the broad peak in the vicinity appeared to be shifted to the higher wavenumber side was the ratio of M-OH bonds contained in the silicon compound coated iron oxide particles, particularly the ratio of the waveform-separated peaks for M-OH bond 1 (Example 1: 936 cm⁻¹). -1 Nearby, Examples 1-5: 912 cm -1 This indicates that the cause was a decrease in the surrounding area.

[0103] Figure 8 shows the XRD measurement results of silicon compound-coated iron oxide particles obtained in Examples 1-5. As can be seen in Figure 8, only peaks originating from α-Fe2O3 were detected in the XRD measurement. In other words, it was confirmed that the silicon compound identified in the above STEM and IR measurements was amorphous.

[0104] Figure 9 shows the reflectance spectra of silicon compound-coated iron oxide particles obtained in Example 1 and Examples 1-2 to 1-5 for light wavelengths from 200 nm to 2500 nm. First, it can be seen that the reflectance for light in the near-infrared region from wavelengths of 780 nm to 2500 nm is higher for the silicon compound-coated iron oxide particles obtained in Example 1-5 than for the silicon compound-coated iron oxide particles obtained in Example 1. In the above IR spectrum, at wavenumber 100 cm⁻¹... -1 From 1250cm -1The peaks in the specified range were waveform-separated, and the area ratio of the M-OH bond peak to the total area of ​​each waveform-separated peak (M-OH ratio [%]) was smallest in the order of Examples 1-5 < 1-4 < 1-3 < 1-2 < 1, while the average reflectance for light rays with wavelengths from 780 nm to 2500 nm was largeest in the order of Examples 1-5 > 1-4 > 1-3 > 1-2 > 1. Figure 10 shows a graph of the average reflectance for light rays with wavelengths from 780 nm to 2500 nm with respect to the M-OH bond / MO bond ratio. In addition to Examples 1 and Examples 1-2 to 1-5, Figure 10 also shows data for the average reflectance for silicon compound-coated iron oxide particles with different heat treatment temperatures and M-OH ratios in addition to Examples 1 and 1-2 to 1-5. As can be seen in Figure 10, there was a tendency for the average reflectance for light rays with wavelengths from 780 nm to 2500 nm to be higher when the M-OH bond / MO bond ratio was lower. In other words, silicon compound-coated iron oxide particles, which are one of the oxide particles of the present invention, are silicon compound-coated iron oxide particles in which the average reflectance to light rays with wavelengths from 780 nm to 2500 nm, which is one of the color characteristics, is controlled by controlling the ratio of M-OH bonds or the M-OH bond / MO bond ratio contained in the silicon compound-coated iron oxide particles. Preferably, the silicon compound-coated iron oxide particles have an increased average reflectance to light rays with wavelengths from 780 nm to 2500 nm by lowering the ratio of M-OH bonds or the M-OH bond / MO bond ratio. More preferably, the silicon compound-coated iron oxide particles have an increased average reflectance to light rays with wavelengths from 780 nm to 2500 nm by setting the M-OH bond / MO bond ratio to 1% or more and 30% or less. When such silicon compound-coated iron oxide particles are used in a coating composition, they are suitable for use as a paint because they have a high effect in suppressing the temperature rise of the coated body when irradiated with sunlight.

[0105] Figure 11 shows a graph of the average reflectance from 780 nm to 2500 nm as a function of the M-OH bond / MO bond ratio for silicon compound-coated iron oxide particles obtained in Example 1, which were heat-treated by standing the aqueous dispersion of silicon compound-coated iron oxide particles at 100°C for 0.5 hours, 1.0 hours, and 2.0 hours. The M-OH bond / MO bond ratio for each treatment time, determined by IR measurement and waveform separation, was 31.0% for Example 1 (no treatment), 23.4% for 0.5-hour treatment, 22.1% for 1.0-hour treatment, and 18.1% for 2.0-hour treatment. As can be seen in Figure 11, it was found that a lower M-OH ratio resulted in a higher average reflectance from 780 nm to 2500 nm. In the present invention, when controlling the M-OH bond / MO bond ratio contained in silicon compound-coated iron oxide particles by heat treatment, it may be done dry or in a dispersed state in a dispersion medium.

[0106] Figure 12 shows the transmission spectrum of a dispersion obtained by dispersing silicon compound-coated iron oxide particles obtained in Example 1 and Example 1-5 in propylene glycol at a concentration of 0.05% by weight as Fe2O3.

[0107] As can be seen in Figure 12, it can be observed that changing the M-OH bond / MO bond ratio of silicon compound-coated iron oxide particles changes the shape of the transmission spectrum. Similar results to those for Examples 1-1 and 1-5 were obtained for Examples 1-2 to 1-4. In the present invention, it is preferable that the M-OH bond / MO bond ratio of the silicon compound-coated iron oxide particles is 1% or more and 31% or less, and that the transmission spectrum of the dispersion obtained by dispersing the silicon compound-coated iron oxide particles in a dispersion medium has a transmittance of 5% or less for light at a wavelength of 380 nm and a transmittance of 80% or more for light at a wavelength of 600 nm.

[0108] Next, silicon compound-coated iron oxide particles were produced by changing the flow rate of the second fluid (Solution B) during the preparation of silicon compound-coated iron oxide particles in Example 1, thereby altering the pH of the discharged liquid. Table 3 shows the preparation conditions and the ratio of M-OH bonds and M-OH bond / MO bond ratio of the silicon compound-coated iron oxide particles obtained in each example. The M-OH bond / MO bond ratio changed by controlling the pH during the precipitation of the silicon compound-coated oxide particles.

[0109] [Table 3]

[0110] Figure 13 shows a graph of the average reflectance for light rays with wavelengths from 780 nm to 2500 nm against the M-OH bond / MO bond ratio of silicon compound-coated iron oxide particles obtained in Examples 1-6 to 1-8. As can be seen in Figure 13, similar to Examples 1 to 1-5, a lower M-OH bond / MO bond ratio tended to result in a higher average reflectance for light rays with wavelengths from 780 nm to 2500 nm.

[0111] Figure 14 also shows a graph of the maximum reflectance (maximum reflectance) for light rays with wavelengths from 400 nm to 620 nm for Example 1 and the silicon compound-coated iron oxide particles obtained by the functional group modification treatment in Example 1. As can be seen in Figure 14, for Example 1 and the silicon compound-coated iron oxide particles obtained by the functional group modification treatment of the silicon compound contained in the silicon compound-coated iron oxide particles in Example 1, when the M-OH bond / MO bond ratio of the silicon compound-coated iron oxide particles is in the range of 14% to 35%, the maximum reflectance for light rays with wavelengths from 400 nm to 620 nm is 18% or less, showing an effect of suppressing the reflection of light other than red. Since such silicon compound-coated iron oxide particles can reduce light other than red, they are suitable for use in coating compositions such as laminated coating films that exhibit a red color.

[0112] Figure 15 shows the average reflectance for light rays with wavelengths from 620 nm to 750 nm relative to the M-OH ratio contained in the silicon compound-coated iron oxide particles of Example 1 and the silicon compound-coated iron oxide particles obtained by the functional group modification treatment in Example 1. As can be seen in Figure 15, in the range where the M-OH bond / MO bond ratio of the silicon compound-coated iron oxide particles is between 10% and 28%, the average reflectance for light rays with wavelengths from 620 nm to 750 nm is 22% or less. Such silicon compound-coated iron oxide particles are preferable because they can reduce the reflectance in the red region and have a greater effect in increasing the difference between highlights and shades when used for laminated coatings. Furthermore, among the examples shown in Figure 15, silicon compound-coated iron oxide particles with an M-OH bond / MO bond ratio of 1% or more and less than 10%, or greater than 28% and 35% or less, and an average reflectance for light rays with wavelengths of 620 nm to 750 nm that is higher than 22%, exhibit a stronger red color compared to silicon compound-coated iron oxide particles with an average reflectance for light rays with wavelengths of 620 nm to 750 nm that is 22% or less. Therefore, they can be suitably used as red pigments, or in general paints to reduce the amount of red pigment used separately when forming a red coating film, or for fine-tuning the color.

[0113] Figure 16 shows the L ratio for Example 1 and the silicon compound-coated iron oxide particles obtained by the functional group modification treatment in the silicon compound-coated iron oxide particles of Example 1. * a * b * Hue H(=b) in a color system * / a * A graph of ) is shown. In addition, Table 4 shows the hue H of the silicon compound coated iron oxide particles obtained in Example 1 and Examples 1-2 to 1-5. As can be seen in Table 4, it was found that the hue H can be controlled by controlling the M-OH bond / MO bond ratio. The silicon compound coated iron oxide particles of the present invention have an M-OH bond / MO bond ratio of 2% or more and 25% or less, L * a * b *In a color system, hue H(=b * / a * Preferably, the value is in the range of 0.5 to 0.9.

[0114] [Table 4]

[0115] Figure 17 shows the absorption spectrum of the dispersion obtained in Examples 1 and 1-5 by dispersing silicon compound-coated iron oxide particles in propylene glycol, and a graph of the molar extinction coefficient calculated from the concentration of silicon compound-coated iron oxide particles (as Fe2O3) in the dispersion used for measurement, against the measurement wavelength. Figure 18 shows a graph of the average molar extinction coefficient at wavelengths from 190 nm to 380 nm against the M-OH bond / MO bond ratio of silicon compound-coated iron oxide particles obtained in Examples 1 and 1-3 to 1-5. Furthermore, Table 5 shows the M-OH bond / MO bond ratio and the average molar extinction coefficient at wavelengths from 190 nm to 380 nm for silicon compound-coated iron oxide particles obtained in Examples 1 and 1-3 to 1-5.

[0116] [Table 5]

[0117] As shown in Figure 18 and Table 5, a tendency was observed for the average molar extinction coefficient to increase as the M-OH bond / MO bond ratio decreased. In the present invention, the silicon compound-coated iron oxide particles preferably have an M-OH bond ratio of 5% to 35%, and the average molar extinction coefficient for light rays with wavelengths from 190nm to 380nm is 2200 L / (mol·cm) or higher in a dispersion liquid obtained by dispersing the silicon compound-coated iron oxide particles in a dispersion medium. When the molar extinction coefficient rises to this level, the design of coating or film-like compositions becomes easier. That is, protection from ultraviolet rays becomes possible by incorporating only a very small amount of silicon compound-coated iron oxide. Furthermore, by utilizing the red coloration of the iron oxide, it is possible to produce coatings, films, and glass with highly decorative properties ranging from light skin tones to highly vibrant reds.

[0118] Figure 19 shows the reflectance spectra of silicon compound-coated iron oxide particles of Examples 1-9, in which acetoxylyl groups were imparted to silicon compound-coated iron oxide particles obtained in Example 1 by reacting the hydroxyl groups and acetyl groups contained in the silicon compound-coated iron oxide particles obtained in Example 1, as a functional group modification treatment for silicon compound-coated iron oxide particles. Table 6 shows the M-OH bond / MO bond ratio calculated from the IR spectrum and waveform separation, and the average reflectance for light rays with wavelengths from 780 nm to 2500 nm. The silicon compound-coated iron oxide particles of Examples 1-9 were prepared by the following procedure to impart acetoxylyl groups, which are ester groups, to the silicon compound-coated iron oxide particles obtained in Example 1. First, 1 part by weight of silicon compound-coated iron oxide particles obtained in Example 1 was added to 99 parts by weight of propylene glycol (manufactured by Kishida Chemical Co., Ltd.), and the mixture was dispersed for 1 hour at 65°C and a rotor speed of 20,000 rpm using a high-speed rotary dispersion emulsifier called Creamix (product name: CLM-2.2S, manufactured by M-Technique Co., Ltd.) to prepare a dispersion. To the above propylene glycol dispersion of silicon compound-coated iron oxide particles, 2 parts by weight of pyridine (manufactured by Kanto Chemical Co., Ltd.) and 1 part by weight of acetic anhydride (manufactured by Kishida Chemical Co., Ltd.) were added per 1 part by weight of silicon compound-coated iron oxide particles, and the mixture was dispersed for 1 hour at 65°C and a rotor speed of 20,000 rpm using the same high-speed rotary dispersion emulsifier. The resulting solution was centrifuged at 26,000 G for 15 minutes, and the supernatant was separated to obtain a precipitate. A portion of the precipitate was dried at -0.10 MPaG and 25°C for 20 hours to obtain a dry powder. TEM observation confirmed that the silicon compound-coated iron oxide particles obtained in Examples 1-9 were substantially the same as the silicon compound-coated iron oxide particles obtained in Example 1.

[0119] Figure 20 shows the FT-IR (infrared absorption spectrum) measurement results of silicon compound-coated iron oxide particles obtained in Example 1 and Examples 1-9. The FT-IR measurement results of the silicon compound-coated iron oxide particles obtained in Examples 1-9, which were obtained by adding an acetoxylyl group to the silicon compound-coated iron oxide particles obtained in Example 1, show a similar effect to the 2900 cm⁻¹ measurement results of the silicon compound-coated iron oxide particles obtained in Example 1. -1 From 3600cm-1 The broad peak originating from nearby hydroxyl groups becomes smaller, at 1450 cm. -1 Nearby and 1600cm -1 A novel peak was detected in the vicinity. It is thought that the hydroxyl groups and acetyl groups in the silicon compound-coated iron oxide particles obtained in Example 1 reacted to form ester bonds, thereby conferring acetoxylyl groups to the silicon compound-coated iron oxide particles. Furthermore, at 800 cm -1 1250cm from the vicinity -1 Changes were also observed in the nearby peaks. At wavenumber 100 cm⁻¹ in the IR spectra of Examples 1 and 1-9... -1 From 1250cm -1 The waveform was separated within this range, and the M-OH bond / MO bond ratio was calculated. The results, along with the average reflectance for light rays with wavelengths from 780 nm to 2500 nm, are shown in Table 6. Furthermore, the results for silicon compound-coated iron oxide particles obtained in Example 1-10, which was obtained under all the same conditions as in Example 1-9 (where pyridine and acetic anhydride were added and dispersed for 1 hour at 65°C and a rotor speed of 20000 rpm using the high-speed rotary dispersion emulsifier), except that the temperature was changed to 80°C and the dispersion treatment time to 2 hours, are also shown in Table 6 and Figure 19.

[0120] As can be seen in Figure 19 and Table 6, by reacting acetyl groups with hydroxyl groups contained in silicon compound-coated iron oxide particles, the M-OH bond / MO bond ratio is reduced, and the average reflectance for light rays with wavelengths from 780 nm to 2500 nm is increased. As can be seen in Table 6, compared to Example 1, Examples 1-9 and 1-10, which have a lower M-OH bond / MO bond ratio, tended to have a higher average reflectance for light rays with wavelengths from 780 nm to 2500 nm. In the present invention, it is preferable that the silicon compound of the silicon compound-coated oxide particles contains ester bonds, the M-OH bond / MO bond ratio is 5% or more and 30% or less, and the average reflectance for light rays with wavelengths from 780 nm to 2500 nm is 50% or more.

[0121] [Table 6]

[0122] (Examples 1-11 to 1-13) Next, silicon compound-coated iron oxide particle dispersions, which were discharged from the fluid processing apparatus in Example 1 and recovered in a beaker, were processed using the dispersion modification apparatus 100 shown in Figure 34, except that they were prepared in the same manner as in Example 1. The dispersion modification apparatus 100 is an example of an apparatus in which the above-mentioned dispersion apparatus and filtration membrane are connected. The dispersion modification apparatus 100 in Figure 34 is a representative example of an apparatus that can be used to remove impurities from a silicon compound-coated iron oxide particle dispersion and to control the M-OH bond / MO bond ratio according to an embodiment of the present invention when adjusting the pH and conductivity of the silicon compound-coated iron oxide particle dispersion. Specifically, the dispersion modification apparatus 100 comprises a dispersion processing apparatus 110, a removal unit 120 equipped with a filtration membrane, and a containment container 130, which are connected by a piping system. The dispersion processing apparatus 110 mainly comprises a dispersion container 101 and a disperser 102 laid therein.

[0123] In Example 1, the silicon compound-coated iron oxide particle dispersion L1, which was discharged from the fluid processing device and recovered in a beaker, is added to the containment container 130 and the pump 104 is started to supply the silicon compound-coated iron oxide particle dispersion L1 to the dispersion container 101. The silicon compound-coated iron oxide particle dispersion L1 delivered by the pump 104 fills the dispersion container 101 and overflows, and is sent to the removal unit 120, where a portion is discharged as filtrate L3 together with the cross-flow washing liquid L2, and a portion is put back into the containment container 130. It is preferable to equip the containment container 130 with a stirrer 200 to make the concentration of the dispersion uniform. The silicon compound-coated iron oxide particle dispersion that has been put back into the containment container 130 is supplied to the dispersion container 101, and the above dispersion and impurity removal are carried out continuously and repeatedly.

[0124] By modifying a silicon compound-coated iron oxide particle dispersion using the apparatus based on the principle shown in Figure 34, impurities in the aggregates of silicon compound-coated iron oxide particles contained in the dispersion can be released into the dispersion. Then, before re-aggregation progresses over time, that is, while more impurities are present in the liquid of the dispersion, the impurities can be removed. This is effective because it allows for precise control of the M-OH bond ratio and the M-OH bond / MO bond ratio for each individual silicon compound-coated iron oxide particle in a uniformly dispersed state.

[0125] Table 7 shows the conditions under which the M-OH bond / MO bond ratio was controlled using the dispersion modification apparatus 100 shown in Figure 34.

[0126] First, 15 kg of pure water (Table 7: (1), pH 5.89 (measurement temperature: 22.4℃), conductivity 0.80 μS / cm (measurement temperature: 22.4℃)) was added to the containment container 130 shown in Figure 34, and the pure water was supplied to the dispersion container 101, which was fitted with a disperser 102 (Table 7: (3), a high-speed rotary dispersion emulsifier called Creamix, product name: CLM-2.2S, rotor: R1, screen: S0.8-48, manufactured by M-Technique Co., Ltd.). The pure water delivered by pump 104 fills the dispersion container 101 and overflows, and the pure water is passed through the removal section 120 at a rate of 1.5 L / min at 21°C (Table 7: (2), pH 5.89 (measurement temperature: 22.4°C), conductivity 0.80 μS / cm (measurement temperature: 22.4°C)) as a cross-flow washing solution, and a hollow fiber dialyzer (Table 7: (4), membrane area: 2.2 m²) is used as the filtration membrane of the removal section 120. 2 The liquid was sent to a container (made of polysulfone, manufactured by Nikkiso Co., Ltd.), some of which was discharged as filtrate L3 along with the cross-flow cleaning solution, and some of which was returned to the container 130.

[0127] Next, the disperser 102 was started and the rotor speed was set to 20,000 rpm (Table 7: (5), peripheral speed: 31.4 m / s). When the pure water in the containment container 130 was discharged until the amount was 1 L (≒ 1 kg), 14 L (≒ 14 kg) of the silicon compound coated iron oxide particle dispersion (pH 11.02 (measurement temperature 30.6°C)) obtained in Example 1 was added to the containment container 130 (Table 7: (6), (7)). The silicon compound coated iron oxide particle dispersion was mixed with the pure water circulating in the apparatus and circulated from the container to the container via the dispersion treatment device and filtration membrane, similar to the pure water described above. At this time, the pH of the silicon compound-coated iron oxide particle dispersion in container 130 was 10.88 (measurement temperature: 26.6°C) (Table 7: (8)), and the conductivity was 8120 μS / cm (measurement temperature: 26.6°C) (Table 7: (9)).

[0128] The silicon compound-coated iron oxide particle dispersion was dispersed in the dispersion container 101 and then sent to the removal unit 120 for filtration, and the filtrate L3 containing impurities was discharged together with the cross-flow washing solution. The silicon compound-coated iron oxide particle dispersion, which was pumped at a flow rate of 8.8 L / min by the pump 104 (Table 7: (10)), was returned to the containment container 130 at a flow rate of 7.3 L / min (Table 7: (11)), so the filtrate L3 containing impurities was discharged at a flow rate of 1.5 L / min by the filtration membrane of the removal unit 120 (Table 7: (12)).

[0129] When the silicon compound-coated iron oxide particle dispersion in container 130 was concentrated to 1.5 L (≒1.5 kg), 13.5 L (≒13.5 kg) of pure water (pH 5.89 (measurement temperature: 22.4°C), conductivity 0.80 μS / cm (measurement temperature: 22.4°C)) was added to container 130 (Table 7: (13), (14)). The operation was continued without changing the operating conditions during and before / after the addition to remove impurities from the silicon compound-coated iron oxide particle dispersion. Between the concentration stage (dispersion volume 1.5 L) and the dilution stage (dispersion volume 15 L), the concentration of silicon compound-coated iron oxide particles in the silicon compound-coated iron oxide particle dispersion fluctuated between 0.4 and 2.0 wt% (Table 7: (15)). Regarding the pressure gauges in Figure 34, both Pa gauges indicated 0.10 MPaG, Pb indicated 0.15 MPaG, and Pc indicated 0.02 MPaG (Table 7: (16), (17), (18)). The immediate transfer path from the dispersion container 101 to the removal unit 120 had a transfer length (Lea) of 0.3 m (Table 7: (19)) and a pipe inner diameter (Leb) of 0.0105 m (Table 7: (20)). The flow velocity of the silicon compound-coated iron oxide particle dispersion in the immediate transfer path was 1.2 m / sec (Table 7: (21)), and the time T1 from the dispersion container 101 until the removal of impurities by the removal unit 120 began was 0.24 sec (0.24 seconds) (Table 7: (22)), which was considered to be less than 3 seconds. Furthermore, the thermometer (not shown) placed inside the dispersion container 101 read 23°C to 26°C (Table 7: (23)), and the temperature of the silicon compound-coated iron oxide particle dispersion in the containment container 130 was 23 to 26°C during processing (Table 7: (24)). For conductivity measurement, an electrical conductivity meter, model ES-51, manufactured by Horiba, Ltd., was used (Table 7: (25)).

[0130] The above-mentioned dispersion treatment of silicon compound-coated iron oxide particle dispersion and the removal of impurities from the silicon compound-coated iron oxide particle dispersion were repeated until the pH of the silicon compound-coated iron oxide particle dispersion reached 6.91 (measurement temperature: 24.6℃) and the conductivity reached 7.14 μS / cm. This removed impurities contained in the aggregates of silicon compound-coated iron oxide particles and modified each silicon compound-coated iron oxide particle in the silicon compound-coated iron oxide particle dispersion.

[0131]

Table 7

[0132] By changing the treatment temperature in the modification treatment of the silicon compound-coated iron oxide particle dispersion shown in (23) and (24) in Table 7, silicon compound-coated iron oxide particles with different M-OH bond / M-O bond ratios from Example 1-11 to Example 1-13 were prepared. Table 8 shows the treatment temperature in the modification treatment of the silicon compound-coated iron oxide particle dispersion, the M-OH bond / M-O bond ratio of the obtained silicon compound-coated iron oxide particles, the average reflectance from wavelength 780 nm to 2500 nm, and the average molar absorption coefficient from wavelength 190 nm to 380 nm together with the results of Example 1.

[0133]

Table 8

[0134] As can be seen from Table 8, the lower the M-OH bond / M-O bond ratio, the higher the average reflectance from wavelength 780 nm to 2500 nm and the average molar absorption coefficient from wavelength 190 nm to 380 nm tend to be. It was found that the color characteristics can be controlled by controlling the M-OH bond / M-O bond ratio.

[0135] (Example 2) In Example 2, silicon compound-coated zinc oxide particles obtained by coating at least a part of the surface of zinc oxide particles with a silicon compound will be described. Using a high-speed rotary dispersion emulsification device, ClearMix (product name: CLM-2.2S, manufactured by M-Technique Co., Ltd.), an oxide precipitation solvent (solution A), an oxide raw material solution (solution B), and a silicon compound raw material solution (solution C) were prepared. Specifically, based on the formulation of the oxide raw material solution shown in Example 2 of Table 9, each component of the oxide raw material solution was homogeneously mixed by stirring at a preparation temperature of 40 °C and a rotor rotation speed of 20,000 rpm for 30 minutes using ClearMix to prepare the oxide raw material solution. Also, based on the formulation of the oxide precipitation solvent shown in Example 2 of Table 9, each component of the oxide precipitation solvent was homogeneously mixed by stirring at a preparation temperature of 45 °C and a rotor rotation speed of 15,000 rpm for 30 minutes using ClearMix to prepare the oxide precipitation solvent. Further, based on the formulation of the silicon compound raw material solution shown in Example 2 of Table 9, each component of the silicon compound raw material solution was homogeneously mixed by stirring at a preparation temperature of 20 °C and a rotor rotation speed of 6,000 rpm for 10 minutes using ClearMix to prepare the silicon compound raw material solution. Regarding the substances indicated by the chemical formulas and abbreviations described in Table 9, MeOH is methanol (manufactured by Godo Co., Ltd.), 97 wt% H2SO4 is concentrated sulfuric acid (manufactured by Kishida Chemical Co., Ltd.), KOH is potassium hydroxide (manufactured by Nippon Soda Co., Ltd.), 35 wt% HCl is hydrochloric acid (manufactured by Kanto Chemical Co., Ltd.), TEOS is tetraethyl orthosilicate (manufactured by Wako Pure Chemical Industries, Ltd.), and ZnO is zinc oxide (manufactured by Kanto Chemical Co., Ltd.).

[0136] Next, the prepared oxide raw material solution, oxide precipitation solvent, and silicon compound raw material solution were mixed using the fluid treatment device described in Patent Document 7 by the applicant of the present application. The treatment method for each fluid and the recovery method for the treatment liquid were carried out in the same procedure as in Example 1.

[0137] Table 10 shows, similar to Example 1, the operating conditions of the fluid treatment apparatus, the average primary particle size calculated from TEM observation results of the obtained silicon compound-coated zinc oxide particles, and the Si / Zn molar ratio calculated from TEM-EDS analysis, along with the calculated values ​​from the formulations and introduction flow rates of solutions A, B, and C. pH measurement, analysis, and particle washing methods were also carried out in the same manner as in Example 1.

[0138] [Table 9]

[0139] [Table 10]

[0140] Figure 21 shows the STEM mapping results of the silicon compound-coated zinc oxide particles obtained in Example 2, and Figure 22 shows the line analysis results at the dashed lines in the HAADF image in Figure 21. As can be seen in Figures 21 and 22, the silicon compound-coated zinc oxide particles obtained in Example 2 were not entirely covered with the silicon compound; silicon compound-coated zinc oxide particles in which only a portion of the surface of the zinc oxide particle was coated with the silicon compound were also observed.

[0141] The silicon compound-coated zinc oxide particles obtained in Example 2 were heat-treated using an electric furnace as a treatment to modify the functional groups contained in the silicon compound-coated zinc oxide particles. The heat treatment conditions were: Example 2: untreated, Example 2-2: 200°C, Example 2-3: 400°C, Example 2-4: 600°C, and the heat treatment time was 30 minutes at each heat treatment temperature. Figure 23 shows the STEM mapping results of the silicon compound-coated zinc oxide obtained in Example 2-4, and Figure 24 shows the line analysis results at the dashed lines in the HAADF image of Figure 23. As can be seen in Figures 23 and 24, the silicon compound-coated zinc oxide particles obtained in Example 2-4 were observed as zinc oxide particles with the entire particle covered by the silicon compound.

[0142] Figure 25 shows the reflectance spectra of silicon compound-coated zinc oxide particles obtained in Example 2 and Examples 2-2 to 2-4 for light rays with wavelengths from 200 nm to 2500 nm.

[0143] As can be seen in Figure 25, the silicon compound-coated zinc oxide particles obtained in Example 2-4 have a higher reflectivity for light in the near-infrared region with wavelengths from 780 nm to 2500 nm than the silicon compound-coated zinc oxide particles obtained in Example 2. The M-OH bond / MO bond ratio for each example decreases in the order of Example 2-4 < 2-3 < 2-2 < 2, and the average reflectivity for light with wavelengths from 780 nm to 2500 nm increases in the order of Example 2-4 > 2-3 > 2-2 > 2. Figure 26 shows a graph of the average reflectivity for light with wavelengths from 780 nm to 2500 nm against the above M-OH bond / MO bond ratio. As can be seen in Figure 26, there was a tendency for the average reflectivity for light with wavelengths from 780 nm to 2500 nm to be higher when the M-OH bond / MO bond ratio was lower. Table 11 shows the M-OH bond / MO bond ratio and average reflectance at wavelengths from 780 nm to 2500 nm for silicon compound-coated zinc oxide particles obtained in Example 2 and Examples 2-2 to 2-4.

[0144] [Table 11]

[0145] As shown in Table 11, it was found that a lower M-OH bond / MO bond ratio results in a higher average reflectance at wavelengths from 780 nm to 2500 nm. In the present invention, silicon compound-coated zinc oxide particles preferably have an M-OH bond / MO bond ratio of 30% to 43% and an average reflectance of 65% or more for light rays at wavelengths from 780 nm to 2500 nm. When such silicon compound-coated zinc oxide particles are used in a coating composition, they are suitable for use as a paint because they have a high effect in suppressing the temperature rise of the coated body when irradiated with sunlight.

[0146] Figure 27 shows the reflectance spectra of silicon compound-coated zinc oxide particles obtained in Example 2, Examples 2-2 to 2-4, and zinc oxide particles obtained in Example 5 for light wavelengths from 200 nm to 780 nm. By changing the M-OH bond / MO bond ratio of the silicon compound-coated zinc oxide particles, a change was observed in the absorption region from 340 nm to 380 nm. Furthermore, the silicon compound-coated zinc oxide particles obtained in Examples 2-3 to 2-4 have an M-OH bond ratio of 30% to 40% and the wavelength at which the reflectance is 15% is 375 nm or higher, so they absorb light in a wider ultraviolet region. Therefore, they are suitable as coating compositions for UV shielding, or as film-like compositions or transparent material compositions for use on glass, etc. Table 12 shows the M-OH bond / MO bond ratio and the average reflectance for light wavelengths from 380 nm to 780 nm for the silicon compound-coated zinc oxide particles obtained in Example 2, Examples 2-2 to 2-4.

[0147] [Table 12]

[0148] The silicon compound-coated zinc oxide particles obtained in Example 2 and Example 2-2 have an M-OH bond / MO bond ratio of 45% to 50%, an average reflectance of 86% or more for light rays with wavelengths from 380 nm to 780 nm, and reflect light across the entire visible region, making them suitable as a white pigment.

[0149] Figure 28 shows the relationship between the M-OH bond / MO bond ratio of the silicon compound-coated zinc oxide particles and L * a * b * Saturation C in a color system = √((a * ) 2 +(b * ) 2) is shown in the graph. As seen in Fig. 28, the higher the ratio of M-OH bond / M-O bond, the more the chroma tends to decrease. In the present invention, the ratio of M-OH bond / M-O bond contained in the silicon compound-coated zinc oxide particles is 31% or more and 50% or less, and L * a * b * In the color system, the chroma C (= √((a * )) 2 +(b * )) 2 ) is preferably a silicon compound-coated zinc oxide particle in the range of 0.5 to 13.

[0150] Fig. 29 shows the L * a * b * graph of the L * value in the color system with respect to the ratio of M-OH bond / M-O bond of the silicon compound-coated zinc oxide particles. As seen in Fig. 29, the higher the ratio of M-OH bond / M-O bond, the more the L * value tends to decrease. In the present invention, the ratio of M-OH bond / M-O bond of the silicon compound-coated zinc oxide particles is 31% or more and 50% or less, and L * a * b * In the color system, the chroma C (= √((a * )) 2 +(b * )) 2 ) is in the range of 0.5 to 13, and L * a * b * It is preferably a silicon compound-coated zinc oxide particle in which the L * value in the color system is in the range of 95 to 97. Thereby, silicon compound-coated zinc oxide particles with high whiteness are obtained, and it is suitable for use as a white pigment.

[0151] Figure 30 shows the transmission spectrum of a dispersion obtained by dispersing silicon compound-coated zinc oxide particles obtained in Example 2 and Examples 2-2 to 2-4 in propylene glycol at a concentration of 0.011 wt% as ZnO. Table 13 shows the M-OH bond / MO bond ratio and the average transmittance for light rays with wavelengths from 380 nm to 780 nm in the transmission spectrum of the silicon compound-coated zinc oxide particles obtained in Example 2 and Examples 2-2 to 2-4.

[0152] [Table 13]

[0153] In Examples 2 and 2-2 to 2-4, it can be seen that the M-OH bond / MO bond ratio decreases, and the absorption edge in the region below 380 nm shifts to the longer wavelength side. Furthermore, the silicon compound-coated zinc oxide particles obtained in Examples 2 to 2-4 have higher transmittance from 380 nm to 780 nm compared to the zinc oxide particles obtained in Example 5, indicating that they efficiently absorb light in the ultraviolet region, from 200 nm to 380 nm, and also have higher transparency. In the present invention, it is preferable that the silicon compound-coated zinc oxide particles have an M-OH bond / MO bond ratio of 47% to 50%, and that the transmission spectrum of the dispersion of the silicon compound-coated zinc oxide particles in a dispersion medium has a transmittance of 10% or less for light at a wavelength of 340 nm, and an average transmittance of 92% or more for light at wavelengths from 380 nm to 780 nm. This makes it suitable for use in cosmetics such as lipsticks, foundations, and sunscreens, as well as coating compositions intended for application to the skin, and film-like compositions used on coatings, painted bodies, and glass, as it enables the realization of coating compositions that balance the ability to absorb ultraviolet light with wavelengths of 380 nm or less with transparency. Furthermore, the transmission spectra of the silicon compound coated oxides obtained in Examples 2-3 and 2-4 show that the absorption region in the ultraviolet range from 200 nm to 380 nm is shifted to longer wavelengths compared to Example 2. In the present invention, it is preferable that the M-OH bond / MO bond ratio of the silicon compound coated zinc oxide particles is 30% or more and 40% or less, and that the wavelength at which the transmittance is 15% in the transmission spectrum of the dispersion of silicon compound coated zinc oxide particles in a dispersion medium is 365 nm or more. This makes it possible to absorb light in the ultraviolet range from 200 nm to 380 nm over a wide range.

[0154] Figure 31 shows the absorption spectrum measurement results of dispersions obtained by dispersing silicon compound-coated zinc oxide particles obtained in Example 2 and Examples 2-2 to 2-4 in propylene glycol, and a graph of the molar extinction coefficient calculated from the concentration of silicon compound-coated zinc oxide particles (as ZnO) in the dispersion used for measurement. Table 14 shows the M-OH bond / MO bond ratio of the silicon compound-coated zinc oxide particles obtained in each example, and the average molar extinction coefficient at wavelengths from 200 nm to 380 nm, along with the average molar extinction coefficient at wavelengths from 200 nm to 380 nm of the zinc oxide particles obtained in Example 5.

[0155] [Table 14]

[0156] As shown in Table 14, a tendency was observed for the average molar extinction coefficient to increase as the M-OH bond / MO bond ratio decreased. Furthermore, it can be seen that the silicon compound-coated zinc oxide particles obtained in Examples 2 to 2-4 had a higher average molar extinction coefficient at wavelengths of 200 nm to 380 nm compared to the zinc oxide particles obtained in Example 5. In the present invention, it is preferable that the silicon compound-coated zinc oxide particles have an M-OH bond / MO bond ratio of 30% to 50%, and that the molar extinction coefficient for light rays at wavelengths of 200 nm to 380 nm in a dispersion liquid obtained by dispersing the silicon compound-coated zinc oxide particles in a dispersion medium is 700 L / (mol·cm) or higher. This makes it possible to efficiently absorb ultraviolet light rays at wavelengths of 200 nm to 380 nm, such as UVA, UVB, and UVC, and is therefore suitable for use in coatings or film compositions, as it allows for reduced usage and further transparency.

[0157] (Examples 2-5 to 2-7) Next, silicon compound-coated zinc oxide particles were prepared in the same manner as in Example 1, except that the silicon compound-coated zinc oxide particle dispersion discharged from the fluid processing apparatus in Example 2 and recovered in a beaker was treated using the dispersion modification apparatus 100 shown in Figure 34. Table 15 shows the conditions under which the M-OH bond / MO bond ratio of the silicon compound-coated zinc oxide particles was controlled using the dispersion modification apparatus 100 in Figure 34. Except for the contents described in Table 15, silicon compound-coated zinc oxide particles with the M-OH bond ratio controlled were obtained in the same manner as in Examples 1-11 to 1-13.

[0158] The above-mentioned dispersion treatment of silicon compound-coated zinc oxide particle dispersion and the removal of impurities from the silicon compound-coated zinc oxide particle dispersion were repeated until the pH of the silicon compound-coated zinc oxide particle dispersion reached 7.02 (measurement temperature: 23.1℃) and the conductivity reached 0.06 μS / cm. This removed impurities contained in the aggregates of silicon compound-coated zinc oxide particles and modified each silicon compound-coated zinc oxide particle in the silicon compound-coated zinc oxide particle dispersion.

[0159] [Table 15]

[0160] By changing the processing temperature in the modification treatment of the silicon compound-coated zinc oxide particle dispersion, as shown in (23) and (24) in Table 15, silicon compound-coated zinc oxide particles with different M-OH bond / MO bond ratios were prepared, as shown in Examples 2-5 to 2-7. Table 16 shows the processing temperature in the modification treatment of the silicon compound-coated zinc oxide particle dispersion, the M-OH bond / MO bond ratio of the obtained silicon compound-coated zinc oxide particles, and the average reflectance from 780 nm to 2500 nm, the average reflectance from 380 nm to 780 nm, the average transmittance from 380 nm to 780 nm, and the average molar extinction coefficient from 200 nm to 380 nm, along with the results for Example 2.

[0161] [Table 16]

[0162] As shown in Table 16, a lower M-OH bond / MO bond ratio tends to result in higher average reflectance at wavelengths of 780 nm to 2500 nm, average reflectance at wavelengths of 380 nm to 780 nm, average transmittance at wavelengths of 380 nm to 780 nm, and average molar extinction coefficient at wavelengths of 200 nm to 380 nm. This indicates that color characteristics can be controlled by controlling the M-OH ratio.

[0163] (Example 3) Example 3 describes silicon compound-coated cerium oxide particles in which at least a portion of the surface of the cerium oxide particles is coated with a silicon compound. Using a high-speed rotary dispersion emulsifier called Creamix (product name: CLM-2.2S, manufactured by M-Technique Co., Ltd.), oxide precipitation solvent (solution A), oxide raw material solution (solution B), and silicon compound raw material solution (solution C) were prepared. Specifically, based on the oxide raw material solution formulation shown in Example 3 in Table 17, each component of the oxide raw material solution was homogeneously mixed using Creamix by stirring at a preparation temperature of 40°C and a rotor rotation speed of 20,000 rpm for 30 minutes to prepare the oxide raw material solution. Similarly, based on the oxide precipitation solvent formulation shown in Example 3 in Table 17, each component of the oxide precipitation solvent was homogeneously mixed using Creamix by stirring at a preparation temperature of 45°C and a rotor rotation speed of 15,000 rpm for 30 minutes to prepare the oxide precipitation solvent. Furthermore, based on the silicon compound raw material solution formulation shown in Example 3 of Table 17, each component of the silicon compound raw material solution was homogeneously mixed using a Creamix at a preparation temperature of 20°C and a rotor rotation speed of 6000 rpm for 10 minutes to prepare the silicon compound raw material solution. For the substances indicated by the chemical formulas and abbreviations listed in Table 17, DMAE was dimethylaminoethanol (manufactured by Kishida Chemical Co., Ltd.), 60wt%HNO3 was concentrated nitric acid (manufactured by Kishida Chemical Co., Ltd.), Ce(NO3)3·6H2O was cerium(III) nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.), and TEOS was tetraethyl orthosilicate (manufactured by Wako Pure Chemical Industries, Ltd.).

[0164] Next, the prepared oxide raw material solution, oxide precipitation solvent, and silicon compound raw material solution were mixed using the fluid processing apparatus described in Patent Document 7 by the present applicant. The treatment method for each fluid and the recovery method for the treated liquid were carried out in the same manner as in Example 1.

[0165] Table 18 shows, similar to Example 1, the operating conditions of the fluid processing apparatus, the average primary particle size calculated from TEM observation results of the obtained silicon compound-coated cerium oxide particles, and the Si / Ce molar ratio calculated from TEM-EDS analysis, along with the calculated values ​​from the formulations and introduction flow rates of solutions A, B, and C. pH measurement, analysis, and particle washing methods were also carried out in the same manner as in Example 1.

[0166] [Table 17]

[0167] [Table 18]

[0168] Figure 32 shows a TEM image of the silicon compound-coated cerium oxide particles obtained in Example 3. In Example 3, some silicon compound-coated cerium oxide particles were observed in which only a portion of the surface of the cerium oxide particle was coated with the silicon compound, rather than the entire particle being covered with the silicon compound.

[0169] The silicon compound-coated cerium oxide particles obtained in Example 3 were heat-treated using an electric furnace to modify the functional groups contained in the silicon compound-coated cerium oxide particles. The heat treatment conditions were: Example 3: untreated, Example 3-2: 200°C, Example 3-3: 400°C, and the heat treatment time was 30 minutes at each heat treatment temperature.

[0170] Figure 33 shows the absorption spectrum measurement results of the dispersion obtained by dispersing silicon compound-coated cerium oxide particles obtained in Example 3 in propylene glycol, and a graph of the molar extinction coefficient calculated from the concentration of cerium oxide in the dispersion. Table 19 shows the M-OH bond / MO bond ratio of the silicon compound-coated cerium oxide particles obtained in each example, and the average molar extinction coefficient at wavelengths from 200 nm to 380 nm, for comparison with the average molar extinction coefficient at wavelengths from 200 nm to 380 nm of the cerium oxide particles obtained in Example 8.

[0171] [Table 19]

[0172] As shown in Table 19, a tendency was observed for the average molar extinction coefficient to increase as the M-OH bond / MO bond ratio decreased. Furthermore, it can be seen that the silicon compound-coated cerium oxide particles obtained in the examples had a higher average molar extinction coefficient at wavelengths of 200 nm to 380 nm compared to the cerium oxide particles obtained in Example 8. In the present invention, it is preferable that the silicon compound-coated cerium oxide particles have an M-OH bond / MO bond ratio of 25% to 40%, and that the molar extinction coefficient for light rays at wavelengths of 200 nm to 380 nm in a dispersion liquid obtained by dispersing the silicon compound-coated cerium oxide particles in a dispersion medium is 4000 L / (mol·cm) or more. This makes it possible to efficiently absorb ultraviolet light rays at wavelengths of 200 nm to 380 nm, such as UVA, UVB, and UVC, and is therefore preferable when used in coating compositions, as it allows for reduced usage and further transparency.

[0173] As described above, the method for producing oxide particles of the present invention enables delicate and precise control of the color characteristics of silicon compound-coated oxide particles. As a result, when used in coating compositions, transmission, absorption, hue, saturation, and molar extinction coefficient for light in the ultraviolet, visible, and near-infrared regions can be precisely controlled. Therefore, when applied to the human body, the texture and aesthetics are not impaired, and when used on painted surfaces, the human body and painted surfaces are protected from ultraviolet and near-infrared rays without compromising their design.

[0174] (Example 4) Example 4 describes the process for iron oxide particles. Using a high-speed rotary dispersion emulsifier called Creamix (product name: CLM-2.2S, manufactured by M-Technique Co., Ltd.), an oxide raw material solution (Solution A) and an oxide precipitation solvent (Solution B) were prepared. Specifically, based on the oxide raw material solution formulation shown in Example 4 of Table 20, each component of the oxide raw material solution was homogeneously mixed using the Creamix at a preparation temperature of 40°C and a rotor speed of 20,000 rpm for 30 minutes by stirring, thereby preparing the oxide raw material solution. Similarly, based on the oxide precipitation solvent formulation shown in Example 4 of Table 20, each component of the oxide precipitation solvent was homogeneously mixed using the Creamix at a preparation temperature of 45°C and a rotor speed of 15,000 rpm for 30 minutes by stirring, thereby preparing the oxide precipitation solvent. For the substances indicated by chemical formulas and abbreviations listed in Table 20, NaOH was sodium hydroxide (manufactured by Kanto Chemical Co., Ltd.), and Fe(NO3)3·9H2O was iron nitrate novahydrate (manufactured by Kanto Chemical Co., Ltd.).

[0175] Next, the prepared oxide raw material solution and oxide precipitation solvent were mixed using the fluid processing apparatus described in Patent Document 7 by the applicant. The treatment method for each fluid and the method for recovering the treated solution were carried out in the same manner as in Example 1. In Example 4, the third introduction section d3 and solution C were not used (not shown).

[0176] Table 21 shows the operating conditions of the fluid treatment apparatus and the average primary particle diameter calculated from the TEM observation results of the obtained iron oxide particles, similar to Example 1. pH measurement, analysis, and particle washing methods were also performed in the same manner as in Example 1. TEM observation results showed that the primary particle diameter ranged from approximately 5 nm to 15 nm, and as shown in Table 21, the average primary particle diameter was 9.53 nm.

[0177] [Table 20]

[0178] [Table 21]

[0179] The iron oxide particles obtained in Example 4 were subjected to heat treatment using an electric furnace to modify the functional groups contained in the iron oxide particles. The heat treatment conditions were as follows: Example 4: untreated, Example 4-2: 100°C, Example 4-3: 200°C, Example 4-4: 300°C, and the heat treatment time was 30 minutes at each heat treatment temperature. The iron oxide particles obtained in Examples 4-2 to 4-4 also had a primary particle size of approximately 5 nm to 15 nm.

[0180] Figure 35 shows the XRD measurement results of the iron oxide particles obtained in Example 4. As can be seen in Figure 35, only peaks originating from iron oxide (α-Fe2O3) were detected in the XRD measurement results. Similarly, in the XRD measurement results for Examples 4-2 to 4-4, only peaks originating from iron oxide were detected, as shown in Figure 35.

[0181] Figure 36 shows the FT-IR measurement results obtained by the ATR method for the iron oxide particles obtained in Example 4 and Example 4-4. The IR measurement results for the iron oxide particles obtained in Example 4-4 show a difference compared to the IR measurement results for the iron oxide particles obtained in Example 4, with a difference of 800 cm² originating from the M-OH bond. -1 1250cm from the vicinity -1The broad peak in the vicinity and the 1250 cm peak are caused by the reaction of the M-OH bond with carbon dioxide. -1 Approximately 1750cm from the vicinity -1 The nearby peaks appeared to have shrunk.

[0182] Wavenumber 100 cm in the above IR measurement results -1 From 1250cm -1 The waveform separation results for Example 4 are shown in Figure 37, and for Example 4-4, in Figure 38. Note that in Example 4-4, the waveform-separated peak at the M-OH bond is very small, so a wavelength of 800 cm was used. -1 From 1250cm -1 This is shown along with an enlarged view of the region. Compared to Example 4, the iron oxide particles obtained in Example 4-4 show that the total area of ​​the M-OH bond peaks is smaller than the total area of ​​all waveform-separated peaks, meaning that the M-OH bond / MO bond ratio is smaller.

[0183] Figure 39 shows a graph of the molar extinction coefficients from wavelengths of 190 nm to 780 nm for dispersions of iron oxide particles obtained in Examples 4 and 4-2 to 4-4 dispersed in propylene glycol. Table 22 shows the average molar extinction coefficients for light rays from wavelengths of 190 nm to 380 nm. Figure 40 shows a graph of the average molar extinction coefficients for light rays from wavelengths of 190 nm to 380 nm with respect to the M-OH bond / MO bond ratio of iron oxide particles obtained in Examples 4 and 4-2 to 4-4. As can be seen in Figure 39 and Table 22, the average molar extinction coefficient in the wavelength range of 190 nm to 380 nm improves as the M-OH ratio decreases in the order of Examples 4, 4-2, 4-3, and 4-4.

[0184] [Table 22]

[0185] Furthermore, as shown in Figure 40, unlike the silicon compound-coated iron oxide particles obtained in Example 1, it was found that for the iron oxide particles, by setting the M-OH bond / MO bond ratio to 1% or more and 21% or less, the average molar extinction coefficient for light rays with wavelengths from 190 nm to 380 nm can be set to 1000 L / (mol·cm) or more.

[0186] Figure 41 shows the reflection spectrum measurement results for the iron oxide particles obtained in Example 4 and Examples 4-2 to 4-4 for light rays with wavelengths from 200 nm to 2500 nm, and Figure 42 shows a graph of the average reflectance for light rays with wavelengths from 780 nm to 2500 nm in the near-infrared region, in relation to the M-OH bond / MO bond ratio calculated from the above IR spectra for each example.

[0187] Table 23 shows the average reflectance of iron oxide particles obtained in Example 4 and Examples 4-2 to 4-4 for light rays with wavelengths from 780 nm to 2500 nm.

[0188] [Table 23]

[0189] As shown in Table 23 and Figure 42, a tendency was observed for the average reflectivity to light rays with wavelengths from 780 nm to 2500 nm to increase as the M-OH bond / MO bond ratio decreased. When the M-OH bond / MO bond ratio of iron oxide particles was in the range of 1.0% to 21%, the average reflectivity to light rays in the near-infrared region from 780 nm to 2500 nm was 55% or higher.

[0190] (Examples 4-5 to 4-7) Next, iron oxide particles were prepared in the same manner as in Example 4, except that the iron oxide particle dispersion discharged from the fluid processing apparatus and collected in a beaker in Example 4 was treated using the dispersion modification apparatus 100 shown in Figure 34. Table 24 shows the conditions under which the ratio of M-OH bonds in the iron oxide particles was controlled using the dispersion modification apparatus 100 shown in Figure 34. Except for the contents described in Table 24, iron oxide particles with controlled M-OH bond / MO bond ratios were obtained using the same method as in Examples 1-11 to 1-13.

[0191] The above-mentioned dispersion treatment of iron oxide particle dispersion and the removal of impurities from the iron oxide particle dispersion were repeated until the pH of the iron oxide particle dispersion reached 7.34 (measurement temperature: 23.6℃) and the conductivity reached 6.99 μS / cm. This removed impurities contained in the aggregates of iron oxide particles and also modified each individual iron oxide particle in the iron oxide particle dispersion.

[0192] [Table 24]

[0193] As shown in (23) and (24) of Table 24, iron oxide particles with different M-OH bond / MO bond ratios were prepared by changing the treatment temperature in the modification treatment of the iron oxide particle dispersion, as shown in Examples 4-5 to 4-7. Table 25 shows the treatment temperature in the modification treatment of the iron oxide particle dispersion, the M-OH bond / MO bond ratio of the obtained iron oxide particles, the average reflectance at wavelengths from 780 nm to 2500 nm, the average reflectance at wavelengths from 380 nm to 780 nm, and the average molar extinction coefficient at wavelengths from 190 nm to 380 nm, along with the results for Example 4.

[0194] [Table 25]

[0195] As shown in Table 25, a lower M-OH ratio tends to result in a higher average reflectance at wavelengths from 780 nm to 2500 nm and a higher average molar extinction coefficient at wavelengths from 190 nm to 380 nm. This indicates that color characteristics can be controlled by controlling the M-OH ratio.

[0196] (Examples 4-8) In Example 4-8, iron oxide particles were produced under the same conditions as in Example 4, except that the apparatus and the mixing and reaction method of solution A (oxide raw material solution) and solution B (oxide precipitation solvent) described in Japanese Patent Publication No. 2009-112892 were used. Here, the apparatus described in Japanese Patent Publication No. 2009-112892 is the apparatus shown in Figure 1 of the same publication, with an inner diameter of 80 mm, a gap of 0.5 mm between the outer end of the stirring tool and the inner circumferential side surface of the stirring tank, and a rotation speed of 7200 rpm for the stirring blades. Solution A was introduced into the stirring tank, and solution B was added to a thin film made of solution A pressed against the inner circumferential side surface of the stirring tank and mixed and reacted. TEM observation revealed iron oxide particles with a primary particle diameter of approximately 50 nm to 60 nm.

[0197] The iron oxide particles obtained in Example 4-8 were subjected to heat treatment using an electric furnace as a treatment to modify the functional groups contained in the iron oxide particles. The heat treatment conditions were as follows: Example 4-8: untreated, Example 4-9: 100°C, Example 4-10: 200°C, Example 4-11: 300°C, and the heat treatment time was 30 minutes at each heat treatment temperature. Table 26 shows the average primary particle diameter, M-OH bond / MO bond ratio, average reflectance at wavelengths from 780 nm to 2500 nm, and average molar extinction coefficient at wavelengths from 190 nm to 380 nm for the iron oxide particles obtained in Examples 4-8 to 4-11. The molar extinction coefficient of the iron oxide particles prepared in Examples 4-8 to 4-11 was measured using propylene glycol as the dispersion medium, as in Example 4.

[0198] [Table 26]

[0199] As shown in Table 26, even when using iron oxide particles prepared using a different apparatus than that used in Examples 1 to 4, it was found that the M-OH bond / MO bond ratio could be controlled by modifying the functional groups contained in the iron oxide particles with a primary particle diameter of 100 nm or less. By controlling the M-OH bond / MO bond ratio, it was found that the average molar extinction coefficient at wavelengths from 190 nm to 380 nm and the average reflectance at wavelengths from 780 nm to 2500 nm could be controlled.

[0200] (Comparative Example 1) For iron oxide particles (special grade iron(III) oxide (α-Fe2O3) manufactured by Wako Pure Chemical Industries, Ltd.) with a primary particle diameter of 150 nm to 250 nm, heat treatment using an electric furnace was performed to modify the functional groups contained in the iron oxide particles in order to change the M-OH bond / MO bond ratio. The heat treatment conditions were: Comparative Example 1-1: untreated, Comparative Example 1-2: 100°C, Comparative Example 1-3: 300°C, and the heat treatment time was 30 minutes at each heat treatment temperature. Table 27 shows the M-OH bond / MO bond ratio and the average molar extinction coefficient for light rays with wavelengths from 190 nm to 380 nm in the dispersion obtained by dispersing in propylene glycol in the same manner as in Example 4 for the iron oxide particles of Comparative Examples 1-1 to 1-3. As can be seen in Table 27, in the case of iron oxide particles with a primary particle diameter exceeding 100 nm, the average molar extinction coefficient was low even when the M-OH bond / MO bond ratio was changed, and no trend was observed. Furthermore, in particular, when comparing Comparative Example 1-1 with Example 4-4, it can be seen that Comparative Example 1-1 has a lower average molar extinction coefficient in the wavelength range of 190 nm to 380 nm, despite having the same M-OH bond / MO bond ratio as the iron oxide particles obtained in Example 4-4, which have a primary particle diameter of 50 nm or less. In the present invention, it was considered that the M-OH bond / MO bond ratio affects the color characteristics when the primary particle diameter is small, such as 50 nm or less, and that the color characteristics can be controlled by controlling the M-OH bond / MO bond ratio when the surface area is increased for the same amount of iron oxide particles.

[0201] [Table 27]

[0202] (Example 5) Example 5 describes zinc oxide particles. The oxide raw material solution and oxide precipitation solvent were prepared using a high-speed rotary dispersion emulsifier called Creamix (product name: CLM-2.2S, manufactured by M-Technique Co., Ltd.). Specifically, based on the oxide raw material solution formulation shown in Example 5 in Table 28, each component of the zinc oxide raw material solution was homogeneously mixed using the Creamix at a preparation temperature of 40°C and a rotor speed of 20,000 rpm for 30 minutes by stirring, thereby preparing the oxide raw material solution. Similarly, based on the oxide precipitation solvent formulation shown in Example 5 in Table 28, each component of the oxide precipitation solvent was homogeneously mixed using the Creamix at a preparation temperature of 45°C and a rotor speed of 15,000 rpm for 30 minutes by stirring, thereby preparing the oxide precipitation solvent. For the substances indicated by the chemical formulas and abbreviations listed in Table 28, MeOH was methanol (manufactured by Gordo Co., Ltd.), 97wt%H2SO4 was concentrated sulfuric acid (manufactured by Kishida Chemical Co., Ltd.), KOH was potassium hydroxide (manufactured by Nippon Soda Co., Ltd.), and ZnO was zinc oxide (manufactured by Kanto Chemical Co., Ltd.).

[0203] Next, the prepared oxide raw material solution and oxide precipitation solvent were mixed using the fluid processing apparatus described in Patent Document 7 by the applicant. The treatment method for each fluid and the method for recovering the treated solution were carried out in the same manner as in Example 1. In Example 5, the third introduction section d3 and solution C were not used (not shown).

[0204] Table 29 shows the operating conditions of the fluid treatment apparatus and the average primary particle diameter calculated from the TEM observation results of the obtained zinc oxide particles, similar to Example 1. pH measurement, analysis, and particle washing methods were also performed in the same manner as in Example 2.

[0205] (Haze value measurement) In addition, the haze value of the zinc oxide particle dispersion was also measured in the evaluation of Example 5. A haze meter (model HZ-V3, manufactured by Suga Test Instruments Co., Ltd.) was used for haze value measurement. The optical conditions were a double-beam system conforming to JIS K 7136 and JIS K 7361, with D65 light as the light source. The measurement was performed using the same dispersion as the one used for transmission spectrum measurement in a 1 mm thick liquid cell.

[0206] [Table 28]

[0207] [Table 29]

[0208] Figure 43 shows a TEM image of the zinc oxide particles obtained in Example 5. The zinc oxide particles obtained in Example 5 had a primary particle diameter of approximately 5 nm to 15 nm, and as shown in Table 29, the average primary particle diameter was 9.4 nm.

[0209] In Example 5, the zinc oxide particles obtained were treated with hydrogen peroxide to modify the functional groups contained in the zinc oxide particles. Specifically, 1 part by weight of the zinc oxide particles obtained in Example 5 was added to 99 parts by weight of propylene glycol (manufactured by Kishida Chemical Co., Ltd.), and the mixture was dispersed for 1 hour at 25°C and a rotor speed of 20,000 rpm using a high-speed rotary dispersion emulsifier called Creamix (product name: CLM-2.2S, manufactured by M-Technique Co., Ltd.) to prepare a dispersion. Hydrogen peroxide solution (manufactured by Kanto Chemical Co., Ltd., purity: 30.9%) was added to the propylene glycol dispersion of zinc oxide particles and dispersed for 15 minutes at 25°C using the high-speed rotary dispersion emulsifier. The resulting solution was centrifuged at 26,000 G for 15 minutes, and the supernatant was separated to obtain a precipitate. A portion of the precipitate was dried at -0.10 MPaG and 25°C for 20 hours to obtain a dry powder.

[0210] The amount of hydrogen peroxide solution was changed to alter the molar ratio of hydrogen peroxide to zinc oxide particles during processing. In Example 5-2, the molar ratio of hydrogen peroxide to zinc oxide particles (H2O2 / ZnO [molar ratio]) was 0.01 molar times, in Example 5-3 it was 0.50 molar times, and in Example 5-4 it was 1.00 molar times. Figure 44 shows a TEM image of the zinc oxide particles obtained in Example 5-4. The zinc oxide particles obtained in Example 5-4 also had a primary particle diameter of approximately 5 nm to 15 nm, with an average primary particle diameter of 9.5 nm.

[0211] Figure 45 shows the XRD measurement results of the zinc oxide particles obtained in Example 5. As can be seen in Figure 45, only peaks originating from zinc oxide (ZnO) were detected in the XRD measurement results. Similarly, in the XRD measurement results for Examples 5-2 to 5-4, only peaks originating from zinc oxide were detected, as shown in Figure 45.

[0212] Figure 46 shows the FT-IR measurement results of zinc oxide particles obtained in Example 5 and Example 5-4 measured by the ATR method. The IR measurement results of the zinc oxide particles obtained in Example 5-4 show a difference of 750 cm² originating from the M-OH bond compared to the IR measurement results of the zinc oxide particles obtained in Example 5. -1 1250cm from the vicinity -1 The broad peak in the vicinity and the 1300 cm peak are thought to be caused by the reaction of the M-OH bond with carbon dioxide. -1 1500cm from the vicinity -1 The nearby peaks appeared to have shrunk.

[0213] Wavenumber 100 cm in the above IR measurement results -1 From 1250cm -1The waveform separation results for Example 5 are shown in Figure 47, for Example 5-2 in Figure 48, and for Example 5-4 in Figure 49. Table 30 shows the molar ratio of hydrogen peroxide to zinc oxide particles (H2O2 / ZnO [molar ratio]), the average primary particle size of the obtained zinc oxide particles, and the M-OH bond / MO bond ratio. As can be seen in Table 30, it was found that the M-OH ratio can be controlled by treating zinc oxide particles with hydrogen peroxide.

[0214] Figure 50 shows a graph of the molar extinction coefficients from 200 nm to 780 nm for dispersions of zinc oxide particles obtained in Example 5 and Examples 5-2 to 5-4 dispersed in propylene glycol, and Table 30 shows the average molar extinction coefficients from 200 nm to 380 nm. As can be seen in Figure 50 and Table 30, it was found that the average molar extinction coefficient from 200 nm to 380 nm can be controlled by controlling the M-OH bond / MO bond ratio.

[0215] Figure 51 shows the reflection spectrum measurements of zinc oxide particles obtained in Example 5 and Examples 5-2 to 5-4 for light rays with wavelengths from 200 nm to 2500 nm, and Table 30 shows the average reflectance at wavelengths from 780 nm to 2500 nm. As can be seen in Figure 51 and Table 30, it was found that the average reflectance at wavelengths from 780 nm to 2500 nm can be controlled by controlling the M-OH bond / MO bond ratio.

[0216] Figure 52 shows the transmission spectra of dispersions obtained by dispersing zinc oxide particles from Examples 5 and 5-2 to 5-4 in propylene glycol at a concentration of 0.011 wt% as ZnO. As the M-OH bond / MO bond ratio decreased, a tendency was observed for the ultraviolet absorption region around 200 nm to 360 nm to shift to longer wavelengths. It was found that by controlling the M-OH bond / MO bond ratio, it is possible to produce zinc oxide particles suitable for use in coating compositions intended for ultraviolet shielding. Table 30 shows the transmittance for light at a wavelength of 330 nm, the average transmittance from 380 nm to 780 nm, and the haze value. For all of Examples 5 and 5-2 to 5-4, the transmittance for light at a wavelength of 330 nm was 10% or less, the average transmittance from 380 nm to 780 nm was 90% or more, and the haze value was 1% or less.

[0217] [Table 30]

[0218] The zinc oxide particles obtained in Example 5 were subjected to heat treatment using an electric furnace as a treatment to modify the functional groups contained in the zinc oxide particles. The heat treatment conditions were as follows: Example 5: untreated, Example 5-5: 100°C, Example 5-6: 200°C, Example 5-7: 300°C, and the heat treatment time was 30 minutes at each heat treatment temperature. Figure 53 shows a TEM image of the zinc oxide particles obtained in Example 5-6. The zinc oxide particles obtained in Example 5-6 had a primary particle diameter of approximately 5 nm to 20 nm, with an average primary particle diameter of 10.4 nm. In addition, the average primary particle diameter of the zinc oxide particles obtained in Example 5-5 was 9.5 nm, and the average primary particle diameter of Example 5-7 was 9.6 nm.

[0219] Figure 54 shows the FT-IR measurement results obtained by the ATR method for zinc oxide particles obtained in Example 5 and Example 5-6. Compared to the zinc oxide particles of Example 5, the zinc oxide particles obtained in Example 5-6 showed a higher peak at a wavelength of 800 cm², which is the peak of the M-OH bond. -1 From 1250cm -1The small size of the peak indicates that the M-OH bond / MO bond ratio is low.

[0220] Figure 55 shows a graph of the molar extinction coefficients from 200 nm to 380 nm for dispersions obtained by dispersing zinc oxide particles obtained in Examples 5 and 5-5 to 5-7, as well as zinc oxide particles with a primary particle diameter exceeding 50 nm obtained in Comparative Example 2-1 (described later), in propylene glycol. Table 31 shows the average molar extinction coefficients for light rays with wavelengths from 200 nm to 380 nm. As can be seen in Figure 55 and Table 31, the average molar extinction coefficient in the 200 nm to 380 nm region improves as the M-OH bond / MO bond ratio decreases in the order of Examples 5, 5-5, 5-6, and 5-7.

[0221] [Table 31]

[0222] As can be seen in Table 31 and Figure 55, it was found that in the range where the M-OH bond / MO bond ratio of zinc oxide particles is 14% or less, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm increases as the M-OH ratio decreases. In the present invention, it is preferable that the zinc oxide particles have an M-OH bond / MO bond ratio of 18% or less and an average molar extinction coefficient of 500 L / (cm·mol) or more in the wavelength region from 200 nm to 380 nm, and it is more preferable that the zinc oxide particles have an M-OH bond / MO bond ratio of 15% or less and an average molar extinction coefficient of 650 L / (cm·mol) or more in the wavelength region from 200 nm to 380 nm.

[0223] Figure 56 shows the reflection spectrum measurement results for zinc oxide particles obtained in Example 5 and Examples 5-5 to 5-7 for light wavelengths from 200 nm to 2500 nm, and Figure 57 shows a graph of the average reflectance for light wavelengths from 780 nm to 2500 nm in the near-infrared region, in relation to the M-OH bond / MO bond ratio calculated from the above IR spectra for each example.

[0224] Figure 58 shows the reflection spectrum measurements of zinc oxide particle powder obtained in Example 5 and Examples 5-5 to 5-7 for light wavelengths from 200 nm to 780 nm. As can be seen in Figure 58, as the M-OH bond / MO bond ratio decreases, there is a tendency for the ultraviolet absorption region around 200 nm to 360 nm to shift to longer wavelengths. Table 32 shows the average reflectance of zinc oxide particles obtained in Example 5 and Examples 5-5 to 5-7 for light wavelengths from 780 nm to 2500 nm, the transmittance at 330 nm in the transmission spectrum of a dispersion obtained by dispersing the zinc oxide particles obtained in the same examples in propylene glycol at a concentration of 0.011 wt% as ZnO, the average transmittance calculated by simply averaging the transmittances at multiple measurement wavelengths for light wavelengths from 380 nm to 780 nm, and the haze value.

[0225] [Table 32]

[0226] As shown in Figures 56, 57, and Table 32, a tendency was observed for the average reflectance to light rays with wavelengths from 780 nm to 2500 nm to increase as the M-OH bond / MO bond ratio decreased. For the zinc oxide particles obtained in Example 5 and Examples 5-5 to 5-7, the average reflectance to light rays in the near-infrared region from 780 nm to 2500 nm was 65% or more, and despite the transmittance of the zinc oxide particle dispersion being 10% or less for light rays with a wavelength of 330 nm, the average transmittance to light rays with wavelengths from 380 nm to 780 nm was 90% or more. Furthermore, the haze value was extremely low, ranging from 0.02% to 0.04%.

[0227] (Comparative Example 2) The ratio of M-OH bonds was varied in zinc oxide particles (special grade 3N5, manufactured by Kanto Chemical Co., Ltd.) with a primary particle size ranging from 150 nm to 300 nm. Figure 59 shows a TEM image of Comparative Example 1. As a treatment to change the functional groups contained in the zinc oxide particles, heat treatment was performed using an electric furnace. The heat treatment conditions were: Comparative Example 2-1: untreated, Comparative Example 2-2: 100°C, Comparative Example 2-3: 300°C, and the heat treatment time was 30 minutes at each heat treatment temperature. Table 33 shows the M-OH bond / MO bond ratio, the average molar extinction coefficient for light rays from 200 nm to 380 nm in the dispersion obtained by dispersing the zinc oxide particles of Comparative Examples 2-1 to 2-3 in propylene glycol, the transmittance at 330 nm in the transmission spectrum of the dispersion obtained by dispersing the zinc oxide particles obtained in the same examples in propylene glycol at a concentration of 0.011 wt% as ZnO, the average transmittance for light rays from 380 nm to 780 nm, and the haze value. As can be seen in Table 33, in the case of zinc oxide particles with a primary particle diameter exceeding 50 nm, there was almost no difference in the average molar extinction coefficient, transmittance, and haze value even when the M-OH bond / MO bond ratio was changed, indicating low ultraviolet absorption capacity and low transparency. Furthermore, in particular, when comparing Comparative Example 2-1 with Example 5-7, it can be seen that Comparative Example 2-1 has a lower average molar extinction coefficient in the wavelength range of 200 nm to 380 nm, despite having the same M-OH ratio as the zinc oxide particles obtained in Example 5-7, which have a primary particle diameter of 50 nm or less. In the present invention, it was considered that the M-OH bond / MO bond ratio affects the color characteristics when the primary particle diameter is small, such as 50 nm or less, and that the color characteristics can be controlled by controlling the M-OH bond / MO bond ratio when the surface area is increased for the same amount of zinc oxide particles. In addition, the average primary particle diameter of Comparative Example 2-1 was 228 nm, the average primary particle diameter of Comparative Example 2-2 was 228 nm, and the average primary particle diameter of Comparative Example 2-3 was 225 nm.

[0228] [Table 33]

[0229] (Comparative Example 3) The zinc oxide particles obtained in Example 5 were subjected to heat treatment using an electric furnace to modify the functional groups contained in the zinc oxide particles. The heat treatment conditions were 400°C (Comparative Example 3-1) and 600°C (Comparative Example 3-2), and the heat treatment time was 30 minutes at each heat treatment temperature. TEM images of the zinc oxide particles treated under these heat treatment conditions are shown in Figures 60 (Comparative Example 3-1) and 61 (Comparative Example 3-2). As shown in Figures 60 and 61, clear fusion of zinc oxide particles was observed, and the primary particle diameter exceeded 50 nm. Table 34 shows the M-OH bond / MO bond ratio of zinc oxide particles obtained in Comparative Examples 3-1 and 3-2, the average molar extinction coefficient for light rays from wavelengths of 200 nm to 380 nm in the dispersion obtained by dispersing the same zinc oxide particles in propylene glycol, the transmittance at a wavelength of 330 nm in the transmission spectrum of the dispersion obtained by dispersing the zinc oxide particles obtained in the same example in propylene glycol at a concentration of 0.011 wt% as ZnO, the average transmittance for light rays from wavelengths of 380 nm to 780 nm, and the haze value.

[0230] [Table 34]

[0231] As shown in Table 34, similar to Comparative Example 1, in the case of zinc oxide particles with a primary particle diameter exceeding 50 nm, changing the M-OH bond / MO bond ratio did not result in any significant difference in the average molar extinction coefficient, transmittance, or haze value, indicating low ultraviolet absorption capacity and low transparency.

[0232] (Example 6) In Example 6-1, zinc oxide particles were produced under the same conditions as in Example 5, except that the apparatus and the mixing and reaction method of solution A (oxide raw material solution) and solution B (oxide precipitation solvent) described in Japanese Patent Publication No. 2009-112892 were used. Here, the apparatus described in Japanese Patent Publication No. 2009-112892 is the apparatus shown in Figure 1 of the same publication, with an inner diameter of 80 mm, a gap of 0.5 mm between the outer end of the stirring tool and the inner circumferential side surface of the stirring tank, and a rotation speed of 7200 rpm for the stirring blades. Solution A was introduced into the stirring tank, and solution B was added to a thin film made of solution A pressed against the inner circumferential side surface of the stirring tank and mixed and reacted. TEM observation revealed zinc oxide particles with a primary particle diameter of approximately 30 nm.

[0233] The zinc oxide particles obtained in Example 6-1 were subjected to heat treatment using an electric furnace as a treatment to modify the functional groups contained in the zinc oxide particles. The heat treatment conditions were as follows: Example 6-1: untreated, Example 6-2: 100°C, Example 6-3: 200°C, Example 6-4: 300°C, and the heat treatment time was 30 minutes at each heat treatment temperature. Table 35 shows the average primary particle diameter, M-OH bond / MO bond ratio, average molar extinction coefficient at wavelengths of 200 nm to 380 nm, average reflectance at wavelengths of 780 nm to 2500 nm, transmittance for light at a wavelength of 330 nm, and average transmittance and haze value at wavelengths of 380 nm to 780 nm for the zinc oxide particles obtained in Examples 6-1 to 6-4. The transmittance and molar extinction coefficient of the zinc oxide particles prepared in Examples 6-1 to 6-4 were measured using propylene glycol as the dispersion medium, as in Example 5.

[0234] [Table 35]

[0235] As shown in Table 35, even when zinc oxide particles produced using a different apparatus than that used in Examples 1 to 5 were used, it was found that the M-OH bond / MO bond ratio could be controlled by modifying the functional groups contained in the zinc oxide particles with a primary particle diameter of 50 nm or less. By controlling the M-OH bond / MO bond ratio, it was found that the average molar extinction coefficient at wavelengths from 200 nm to 380 nm and the average reflectance at wavelengths from 780 nm to 2500 nm could be controlled. Furthermore, for all of Examples 6-1 to 6-4, the transmittance to light at a wavelength of 330 nm was 10% or less, the average transmittance at wavelengths from 380 nm to 780 nm was 90% or more, and the haze value was 1% or less.

[0236] (Comparative Example 4) As Comparative Example 4-1, zinc oxide particles were prepared using the same method as in Example 6-1, except that the gap between the outer end of the stirring tool and the inner surface of the stirring tank was 1 mm, and the rotation speed of the stirring blade was set to one-sixth of the rotation speed in Example 6 (1200 rpm). TEM observation revealed zinc oxide particles with a primary particle diameter of approximately 70 nm.

[0237] The zinc oxide particles obtained in Comparative Example 4-1 were subjected to heat treatment using an electric furnace as a treatment to modify the functional groups contained in the zinc oxide particles. The heat treatment conditions were: Comparative Example 4-1: untreated, Comparative Example 4-2: 100°C, Comparative Example 4-3: 200°C, and the heat treatment time was 30 minutes at each heat treatment temperature. Table 36 shows the average primary particle diameter, M-OH bond / MO bond ratio, average molar extinction coefficient at wavelengths of 200 nm to 380 nm, average reflectance at wavelengths of 780 nm to 2500 nm, transmittance for light at a wavelength of 330 nm, and average transmittance and haze value at wavelengths of 380 nm to 780 nm for the zinc oxide particles obtained in Comparative Examples 4-1 to 4-2. The transmittance and molar extinction coefficient of the zinc oxide particles prepared in Comparative Examples 4-1 to 4-2 were measured using propylene glycol as the dispersion medium, as in Examples 1 to 5.

[0238] [Table 36]

[0239] As shown in Table 36, for zinc oxide particles with a primary particle diameter exceeding 100 nm, it was found that changing the M-OH bond / MO bond ratio did not significantly alter the average molar extinction coefficient at wavelengths from 200 nm to 780 nm or the average reflectance at wavelengths from 780 nm to 2500 nm. Furthermore, under the conditions of Comparative Examples 4-1 to 4-3, the transmittance to light at a wavelength of 330 nm was 10% or more, the average transmittance at wavelengths from 380 nm to 780 nm was less than 90%, and the haze value exceeded 1%.

[0240] (Example 7) Next, in Example 5, zinc oxide particles were prepared in the same manner as in Example 5, except that the zinc oxide particle dispersion discharged from the fluid processing device and collected in a beaker was treated using the dispersion modification device 100 shown in Figure 34. Table 37 shows the conditions under which the M-OH bond / MO bond ratio of the above zinc oxide particles was controlled using the dispersion modification device 100 shown in Figure 34. Except for the contents described in Table 37, zinc oxide particles with controlled M-OH bond / MO bond ratios were obtained in the same manner as in Examples 1-11 to 1-13.

[0241] The above zinc oxide particle dispersion was subjected to dispersion treatment, and the operation of removing impurities from the zinc oxide particle dispersion was repeated until the pH of the zinc oxide particle dispersion reached 7.01 (measurement temperature: 23.2°C) and the conductivity reached 0.04 μS / cm. This removed impurities contained in the aggregates of zinc oxide particles and also modified each individual zinc oxide particle in the zinc oxide particle dispersion.

[0242] [Table 37]

[0243] Zinc oxide particles with different M-OH bond / MO bond ratios were prepared by changing the treatment temperature in the modification treatment of the zinc oxide particle dispersion shown in (23) and (24) of Table 37. Table 38 shows the treatment temperature in the modification treatment of the zinc oxide particle dispersion, the M-OH bond / MO bond ratio of the obtained zinc oxide particles, the average reflectance from wavelengths of 780 nm to 2500 nm, the average reflectance from wavelengths of 380 nm to 780 nm, the average transmittance from wavelengths of 380 nm to 780 nm, the average molar extinction coefficient from wavelengths of 200 nm to 380 nm, and the haze value.

[0244] [Table 38]

[0245] As shown in Table 38, a lower M-OH bond / MO bond ratio tends to result in higher average reflectance at wavelengths of 780 nm to 2500 nm, average reflectance at wavelengths of 380 nm to 780 nm, average transmittance at wavelengths of 380 nm to 780 nm, and average molar extinction coefficient at wavelengths of 200 nm to 380 nm. This indicates that color characteristics can be controlled by controlling the M-OH bond / MO bond ratio.

[0246] (Example 8) Example 8 describes the cerium oxide particles. Using a high-speed rotary dispersion emulsifier called Creamix (product name: CLM-2.2S, manufactured by M-Technique Co., Ltd.), an oxide raw material solution (solution A) and an oxide precipitation solvent (solution B) were prepared. Specifically, based on the oxide raw material solution formulation shown in Example 8 in Table 39, each component of the oxide raw material solution was homogeneously mixed using Creamix by stirring at a preparation temperature of 40°C and a rotor speed of 20,000 rpm for 30 minutes to prepare the oxide raw material solution. Similarly, based on the oxide precipitation solvent formulation shown in Example 8 in Table 39, each component of the oxide precipitation solvent was homogeneously mixed using Creamix by stirring at a preparation temperature of 45°C and a rotor speed of 15,000 rpm for 30 minutes to prepare the oxide precipitation solvent. For the substances indicated by the chemical formulas and abbreviations listed in Table 39, DMAE was represented by dimethylaminoethanol (manufactured by Kishida Chemical Co., Ltd.), and Ce(NO3)3·6H2O was represented by cerium(III) nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.).

[0247] Next, the prepared oxide raw material solution and oxide precipitation solvent were mixed using the fluid processing apparatus described in Patent Document 7 by the applicant. The treatment method for each fluid and the recovery method for the treated solution were carried out in the same manner as in Example 1. In Example 8, the third introduction section d3 and solution C were not used (not shown).

[0248] Table 40 shows the operating conditions of the fluid processing apparatus and the average primary particle diameter calculated from the TEM observation results of the obtained cerium oxide particles, similar to Example 1. pH measurement, analysis, and particle washing methods were also performed in the same manner as in Example 1. TEM observation results showed that the primary particle diameter ranged from approximately 5 nm to 15 nm, and as shown in Table 40, the average primary particle diameter was 5.19 nm.

[0249] [Table 39]

[0250] [Table 40]

[0251] The cerium oxide particles obtained in Example 8 were subjected to heat treatment using an electric furnace to modify the functional groups contained in the iron oxide particles. The heat treatment conditions were as follows: Example 8: untreated, Example 8-2: 100°C, Example 8-3: 200°C, Example 8-4: 300°C, and the heat treatment time was 30 minutes at each heat treatment temperature. The cerium oxide particles obtained in Examples 8-2 to 8-4 also had a primary particle size of approximately 5 nm to 15 nm.

[0252] In the XRD measurements of cerium oxide particles obtained in Example 8 and Examples 8-2 to 8-4, only peaks originating from cerium oxide (CeO2) were detected.

[0253] Table 41 shows the average molar extinction coefficients for light rays with wavelengths from 200 nm to 380 nm, along with the M-OH ratios of the cerium oxide particles obtained in Example 8 and Examples 8-2 to 8-4. As can be seen in Table 41, the average molar extinction coefficient in the wavelength range from 200 nm to 380 nm improves as the M-OH bond / MO bond ratio decreases in the order of Example 8, 8-2, 8-3, and 8-4.

[0254] [Table 41]

[0255] Furthermore, as shown in Table 41, unlike the silicon compound-coated cerium oxide particles obtained in Example 3, it was found that for cerium oxide particles, by setting the M-OH bond / MO bond ratio to 23% or less, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm can be set to 4000 L / (mol·cm) or more. In the present invention, it is preferable that the cerium oxide particles contain an M-OH bond / MO bond ratio of 30% or less and have an average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm of 3500 L / (mol·cm) or more, and it is more preferable that the cerium oxide particles contain an M-OH bond / MO bond ratio of 12% or less and have an average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm of 4000 L / (mol·cm) or more.

[0256] (Examples 8-5 to 8-7) Next, cerium oxide particles were prepared in the same manner as in Example 8, except that the cerium oxide particle dispersion discharged from the fluid processing apparatus and collected in a beaker in Example 8 was treated using the dispersion modification apparatus 100 shown in Figure 34. Table 42 shows the conditions under which the M-OH bond / MO bond ratio of the above cerium oxide particles was controlled using the dispersion modification apparatus 100 of Figure 34. Except for the contents described in Table 42, cerium oxide particles with controlled M-OH bond / MO bond ratios were obtained in the same manner as in Examples 1-11 to 1-13.

[0257] The above cerium oxide particle dispersion was subjected to dispersion treatment, and the operation of removing impurities from the cerium oxide particle dispersion was repeated until the pH of the silicon compound-coated iron oxide particle dispersion reached 7.22 (measurement temperature: 25.6°C) and the conductivity reached 7.77 μS / cm. This removed impurities contained in the aggregates of cerium oxide particles and also modified each individual cerium oxide particle in the cerium oxide particle dispersion.

[0258] [Table 42]

[0259] As shown in (23) and (24) of Table 42, cerium oxide particles with different M-OH bond / MO bond ratios were prepared by changing the treatment temperature in the modification treatment of the cerium oxide particle dispersion, as shown in Examples 8-5 to 8-7. Table 43 shows the treatment temperature in the modification treatment of the cerium oxide particle dispersion, the M-OH bond / MO bond ratio of the obtained cerium oxide particles, and the average molar extinction coefficient at wavelengths from 200 nm to 380 nm, along with the results for Example 8.

[0260] [Table 43]

[0261] As shown in Table 43, a lower M-OH bond / MO bond ratio tends to result in a higher average molar extinction coefficient at wavelengths from 200 nm to 380 nm, indicating that color characteristics can be controlled by controlling the M-OH bond / MO bond ratio.

[0262] (Comparative Example 5) For cerium oxide particles (special grade cerium(IV)(CeO2) manufactured by Wako Pure Chemical Industries, Ltd.) with a primary particle diameter of 120 nm to 200 nm, heat treatment using an electric furnace was performed to modify the functional groups contained in the cerium oxide particles in order to change the M-OH bond / MO bond ratio. The heat treatment conditions were: Comparative Example 1-1: untreated, Comparative Example 1-2: 100°C, Comparative Example 1-3: 300°C, and the heat treatment time was 30 minutes at each heat treatment temperature. Table 44 shows the M-OH bond / MO bond ratio and the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm in the dispersion obtained by dispersing in propylene glycol in the same manner as in Example 8 for the cerium oxide particles of Comparative Examples 1-1 to 1-3. As can be seen in Table 44, in the case of cerium oxide particles with a primary particle diameter exceeding 50 nm, the average molar extinction coefficient was low even when the M-OH bond / MO bond ratio was changed, and no trend was observed. Furthermore, in particular, when comparing Comparative Example 5-1 with Example 8-4, it can be seen that Comparative Example 5-1 has a lower average molar extinction coefficient in the wavelength range of 200 nm to 380 nm, despite having the same M-OH bond / MO bond ratio as the cerium oxide particles obtained in Example 8-4, which have a primary particle diameter of 50 nm or less. In the present invention, it was considered that the M-OH ratio affects the color characteristics when the primary particle diameter is small, such as 50 nm or less, and that the color characteristics can be controlled by controlling the M-OH bond / MO bond ratio when the surface area is increased for the same amount of cerium oxide particles.

[0263] [Table 44]

[0264] (Examples 9 to 11) Examples 9 to 11 describe cobalt-zinc composite oxide particles, which are oxides containing cobalt and zinc, as oxide particles. Using a high-speed rotary dispersion emulsifier called Creamix (product name: CLM-2.2S, manufactured by M-Technique Co., Ltd.), oxide raw material solution (solution A) and oxide precipitation solvent (solution B) were prepared. Specifically, based on the oxide raw material solution formulations shown in Examples 9 to 11 in Table 45, each component of the oxide raw material solution was homogeneously mixed using Creamix by stirring at a preparation temperature of 40°C and a rotor speed of 20,000 rpm for 30 minutes to prepare the oxide raw material solution. Similarly, based on the oxide precipitation solvent formulation shown in Example 9 in Table 45, each component of the oxide precipitation solvent was homogeneously mixed using Creamix by stirring at a preparation temperature of 45°C and a rotor speed of 15,000 rpm for 30 minutes to prepare the oxide precipitation solvent. For the substances indicated by the chemical formulas and abbreviations listed in Table 45, EG was ethylene glycol (manufactured by Kishida Chemical Co., Ltd.), Zn(NO3)2·6H2O was zinc nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.), Co(NO3)2·6H2O was cobalt nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.), and NaOH was sodium hydroxide (manufactured by Kanto Chemical Co., Ltd.).

[0265] Next, the prepared oxide raw material solution and oxide precipitation solvent were mixed using the fluid processing apparatus described in Patent Document 7 by the applicant. The treatment method for each fluid and the method for recovering the treated solution were carried out in the same manner as in Example 1. In Examples 9 to 11, the third introduction section d3 and solution C were not used (not shown).

[0266] Table 46 shows, similar to Example 1, the operating conditions of the fluid treatment apparatus, the average primary particle diameter calculated from TEM observation results of the obtained cobalt-zinc composite oxide particles, and the molar ratio of Co / Zn calculated from TEM-EDS analysis, along with the calculated values ​​from the formulations and introduction flow rates of solutions A and B. pH measurement, analysis, and particle washing methods were also carried out in the same manner as in Example 1.

[0267] [Table 45]

[0268] [Table 46]

[0269] Figure 62 shows the STEM mapping results of the cobalt-zinc composite oxide particles obtained in Example 9, and Figure 63 shows the line analysis results at the dashed lines in the BF image (bright-field image) of Figure 62. Figure 64 shows the line analysis results of the cobalt-zinc composite oxide particles obtained in Example 11, and Figure 65 shows the line analysis results at the dashed lines in the BF image (bright-field image) of Figure 64. As can be seen in Figures 62 to 65, the cobalt-zinc composite oxide particles obtained in Examples 9 and 11 showed cobalt and zinc detected throughout the particles, and were observed as cobalt-zinc composite oxide particles in which cobalt and zinc were uniformly dissolved. Similar particles were observed in Examples 9-2, 9-3, 10, 10-2, 10-3, 11-2, and 11-3, which will be described later.

[0270] The cobalt-zinc composite oxide particles obtained in Examples 9 to 11 were heat-treated using an electric furnace as a treatment to modify the functional groups contained in the cobalt-zinc composite oxide particles. The heat treatment conditions were as follows: Examples 9, 10, and 11: untreated; Examples 9-2, 10-2, and 11-2: 100°C; Examples 9-3, 10-3, and 11-3: 200°C; and Examples 9-4, 10-4, and 11-4: 300°C. The heat treatment time was 30 minutes at each heat treatment temperature.

[0271] Figure 66 shows the transmission spectrum for light wavelengths from 380 nm to 780 nm of a dispersion of cobalt zinc composite oxide particles obtained in Examples 9, 10, and 11, dispersed in propylene glycol at a concentration of 0.05 wt%, and Figure 67 shows the reflection spectrum for light wavelengths from 200 nm to 780 nm of the cobalt zinc composite oxide particle powder obtained in Examples 9, 10, and 11. As can be seen, the cobalt zinc composite oxide particles exhibit a light blue to green color.

[0272] Table 47 shows the M-OH bond / MO bond ratio and the absorption spectrum of the dispersion obtained by dispersing cobalt zinc composite oxide particles in propylene glycol, as well as the average molar extinction coefficient for light rays from 200 nm to 380 nm calculated from the concentration of cobalt zinc composite oxide particles in the measurement solution (as ZnO + Co), for the cobalt zinc composite oxide obtained in Examples 9 and 9-2 to 9-4, Table 48 shows the M-OH bond / MO bond ratio and the absorption spectrum of the dispersion obtained by dispersing cobalt zinc composite oxide particles in propylene glycol, for the cobalt zinc composite oxide obtained in Examples 11 and 11-2 to 11-4, for comparison. For comparison, the zinc oxide particles obtained in Example 5 are also shown.

[0273] [Table 47]

[0274] [Table 48]

[0275] [Table 49]

[0276] As shown in Tables 47 to 49, for cobalt zinc composite oxide particles, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm improved as the M-OH bond / MO bond ratio decreased. For cobalt zinc composite oxide particles, it is preferable that the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 700 L / (mol·cm) or higher when the M-OH bond / MO bond ratio is between 1% and 33%. It was also found that cobalt zinc composite oxide particles have a higher average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm compared to zinc oxide particles. Furthermore, since the cobalt zinc composite oxide particles with the above-mentioned controlled M-OH bond / MO bond ratio exhibit a color ranging from light blue to green, they are suitable for use in film-like compositions such as coatings and glass, effectively improving transparency and UV shielding ability, as well as for purposes such as coloring blue or light blue.

[0277] (Examples 12 to 14) Examples 12 to 14 describe silicon-cobalt-zinc composite oxide particles as oxide particles. Using a high-speed rotary dispersion emulsifier called Creamix (product name: CLM-2.2S, manufactured by M-Technique Co., Ltd.), oxide raw material solution (solution A), oxide precipitation solvent (solution B), and silicon compound raw material solution (solution C) were prepared. Specifically, based on the oxide raw material solution formulations shown in Examples 12 to 14 in Table 50, each component of the oxide raw material solution was homogeneously mixed using Creamix by stirring at a preparation temperature of 40°C and a rotor speed of 20,000 rpm for 30 minutes to prepare the oxide raw material solution. Similarly, based on the oxide precipitation solvent formulations shown in Examples 12 to 14 in Table 50, each component of the oxide precipitation solvent was homogeneously mixed using Creamix by stirring at a preparation temperature of 45°C and a rotor speed of 15,000 rpm for 30 minutes to prepare the oxide precipitation solvent. Furthermore, based on the silicon compound raw material solutions shown in Examples 12 to 14 in Table 50, each component of the silicon compound raw material solution was homogeneously mixed using a Creamix at a preparation temperature of 20°C and a rotor rotation speed of 6000 rpm for 10 minutes to prepare the silicon compound raw material solution. For the substances indicated by the chemical formulas and abbreviations listed in Table 50, EG was ethylene glycol (manufactured by Kishida Chemical Co., Ltd.), Zn(NO3)2·6H2O was zinc nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.), Co(NO3)2·6H2O was cobalt nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.), NaOH was sodium hydroxide (manufactured by Kanto Chemical Co., Ltd.), 60wt%HNO3 was concentrated nitric acid (manufactured by Kishida Chemical Co., Ltd.), and TEOS was tetraethyl orthosilicate (manufactured by Wako Pure Chemical Industries, Ltd.).

[0278] Next, the prepared oxide raw material solution, oxide precipitation solvent, and silicon compound raw material solution were mixed using the fluid processing apparatus described in Patent Document 7 by the present applicant. The treatment method for each fluid and the recovery method for the treated liquid were carried out in the same manner as in Example 1.

[0279] Table 51 shows, similar to Example 1, the operating conditions of the fluid treatment apparatus, the average primary particle diameter calculated from TEM observation results of the obtained silicon-cobalt-zinc composite oxide particles, and the Si / Co / Zn molar ratio calculated from TEM-EDS analysis, along with the calculated values ​​from the formulations and introduction flow rates of solutions A, B, and C. pH measurement, analysis, and particle washing methods were also carried out in the same manner as in Example 1.

[0280] [Table 50]

[0281] [Table 51]

[0282] Figure 68 shows the STEM mapping results of the silicon-cobalt-zinc composite oxide particles obtained in Example 13, and Figure 69 shows the line analysis results at the dashed lines in the BF image (bright-field image) of Figure 68. As can be seen in Figures 68 and 69, silicon-cobalt-zinc composite oxide particles obtained in Example 13 were observed to be silicon-cobalt-zinc composite oxide particles in which silicon, cobalt, zinc, and oxygen were detected throughout the particles, and silicon, cobalt, and zinc were uniformly dissolved. Similar particles were observed in Experimental Examples 12, 12-2, 12-3, 13-2, 13-3, and 14, 14-2, and 14-3, which will be described later.

[0283] The silicon-cobalt-zinc composite oxide particles obtained in Examples 12 to 14 were heat-treated using an electric furnace as a treatment to modify the functional groups contained in the silicon-cobalt-zinc composite oxide particles. The heat treatment conditions were as follows: Examples 12, 13, and 14: untreated; Examples 12-2, 13-2, and 14-2: 100°C; Examples 12-3, 13-3, and 14-3: 200°C; and Examples 12-4, 13-4, and 14-4: 300°C. The heat treatment time was 30 minutes at each heat treatment temperature.

[0284] Figure 70 shows graphs of the reflection spectra of silicon-cobalt-zinc composite oxide particle powders obtained in Examples 12, 13, and 14 for light rays with wavelengths from 200 nm to 780 nm, along with the results for cobalt-zinc composite oxide particle powders obtained in Examples 9, 10, and 11, where the Co / Zn (molar ratio) in the particles was the same, for comparison. As can be seen, compared to the cobalt-zinc composite oxide particles (Examples 9 to 11) which exhibited light blue to green light, the silicon-cobalt-zinc composite oxide particles (Examples 12 to 14) exhibited a stronger blue light due to their higher reflectivity for light rays from 400 nm to 450 nm.

[0285] Table 52 shows the silicon-cobalt-zinc composite oxide particles obtained from Examples 12 and 12-2 to 12-4, as well as the cobalt-zinc composite oxide particles of Example 9, which have the same Co / Zn (molar ratio) but do not contain silicon. Table 53 shows the silicon-cobalt-zinc composite oxide particles obtained from Examples 13 and 13-2 to 13-4, as well as the cobalt-zinc composite oxide particles of Example 10, which have the same Co / Zn (molar ratio) but do not contain silicon. Table 54 shows the silicon-cobalt-zinc composite oxide particles of Examples 14 and 14- For the silicon-cobalt-zinc composite oxide particles obtained in Examples 2 to 14-4, and the cobalt-zinc composite oxide particles of Example 11, which have the same Co / Zn (molar ratio) but do not contain silicon, the M-OH bond / MO bond ratio, the absorption spectrum of the dispersion obtained by dispersing the silicon-cobalt-zinc composite oxide particles in propylene glycol, and the average molar extinction coefficient for light rays from wavelengths of 200 nm to 380 nm calculated from the concentration of cobalt-zinc composite oxide particles in the measurement solution (as ZnO + Co) are shown. For comparison, the zinc oxide particles obtained in Example 5 are also shown.

[0286] [Table 52]

[0287] [Table 53]

[0288] [Table 54]

[0289] As shown in Tables 52 to 54, for silicon-cobalt-zinc composite oxide particles, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm improved as the M-OH bond / MO bond ratio of the particles decreased. For silicon-cobalt-zinc oxide particles, it is preferable that the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 800 L / (mol·cm) or higher by setting the M-OH bond / MO bond ratio of the particles to 13% or more and 40% or less. Furthermore, it was found that silicon compound-coated cobalt-zinc composite oxide particles have a higher average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm compared to cobalt-zinc composite oxide particles. Furthermore, the silicon-cobalt-zinc composite oxide particles with the above-mentioned controlled M-OH bond / MO bond ratio exhibit a light blue to blue (blue-green) color. Therefore, when used in film-like compositions such as coatings and glass, they are suitable for effectively utilizing transparency and UV shielding ability, as well as for purposes such as coloring with blue or light blue.

[0290] As described above, the method for producing oxide particles of the present invention enables delicate and precise control of the color characteristics of oxide particles. As a result, when used in coatings or film-like compositions, transmission, absorption, hue, saturation, and molar extinction coefficient for light in the ultraviolet, visible, and near-infrared regions can be precisely controlled. Therefore, when applied to the human body, it does not impair texture or aesthetics, and when used in painted bodies or as a film, such as on glass, it protects the human body and painted bodies from ultraviolet and near-infrared rays without impairing design.

Claims

1. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 1% or more and 30% or less. Silicon compound coated oxide particles characterized in that the average reflectance of the oxide particles for light rays with wavelengths from 780 nm to 2500 nm is 50% or more.

2. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 14% or more and 35% or less. Silicon compound coated oxide particles characterized in that the maximum reflectance of the oxide particles for light rays with wavelengths from 400 nm to 620 nm is 18% or less.

3. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 10% or more and 28% or less. Silicon compound coated oxide particles characterized in that the average reflectance of the oxide particles for light rays with wavelengths from 620 nm to 750 nm is 22% or less.

4. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 2% to 25%. L * a * b * In a color system, hue H (= b * / a * Silicon compound coated oxide particles characterized by having a coefficient in the range of 0.5 to 0.

9.

5. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 1% or more and 31% or less. Silicon compound coated oxide particles, characterized in that, in the transmission spectrum of a dispersion liquid obtained by dispersing the above oxide particles in a dispersion medium, the transmittance for light with a wavelength of 380 nm is 5% or less, and the transmittance for light with a wavelength of 600 nm is 80% or more.

6. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 5% or more and 35% or less. Silicon compound coated oxide particles, characterized in that, in a dispersion liquid obtained by dispersing the above oxide particles in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 190 nm to 380 nm is 2200 L / (mol·cm) or more.

7. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The above oxide particles contain ester bonds, The M-OH bond / M-O bond ratio of the above oxide particles is 5% or more and 30% or less. Silicon compound coated oxide particles characterized in that the average reflectance of the oxide particles for light rays with wavelengths from 780 nm to 2500 nm is 50% or more.

8. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxides constituting the above oxide particles are iron oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 1% or more and less than 10%, or greater than 28% and 35% or less. Silicon compound coated oxide particles characterized by having an average reflectance of 22% or higher for light rays with wavelengths from 620 nm to 750 nm.

9. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. Silicon compound coated oxide particles characterized in that the M-OH bond / M-O bond ratio of the above oxide particles is 30% or more and 47.5% or less, and the average reflectance for light rays with wavelengths from 780 nm to 2500 nm is 70% or more.

10. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. Silicon compound coated oxide particles characterized in that the M-OH bond / M-O bond ratio of the above oxide particles is 30% or more and 40% or less, and the wavelength at which the reflectance is 15% is 375 nm or more.

11. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 45% or more and 50% or less. Silicon compound coated oxide particles characterized by having an average reflectance of 86% or more for light rays with wavelengths from 380 nm to 780 nm.

12. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 31% or more and 50% or less. L * a * b * In the color system, the chroma C (= √((a * )) 2 +(b * )) 2 is in the range of 0.5 to 13. The silicon compound-coated oxide particles are characterized by this.

13. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 47% or more and 50% or less. Silicon compound coated oxide particles, characterized in that, in the transmission spectrum of a dispersion liquid obtained by dispersing the above oxide particles in a dispersion medium, the transmittance for light rays with a wavelength of 340 nm is 10% or less, and the average transmittance for light rays with wavelengths from 380 nm to 780 nm is 92% or more.

14. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 30% or more and 40% or less. Silicon compound-coated oxide particles, characterized in that, in the transmission spectrum of a dispersion liquid obtained by dispersing the above oxide particles in a dispersion medium, the wavelength at which the transmittance is 15% is 365 nm or higher.

15. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 30% or more and 50% or less. Silicon compound-coated oxide particles, characterized in that, in a dispersion liquid obtained by dispersing the above oxide particles in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 700 L / (mol·cm) or more.

16. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is zinc oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 31% or more and 50% or less. L * a * b * In a color system, saturation C = √((a * ) 2 + (b * ) 2 )) is in the range of 0.5 to 13, L * a * b * In color systems, L * Silicon compound coated oxide particles characterized by having a value in the range of 95 to 97.

17. Silicon compound coated oxide particles, wherein at least a portion of the surface of the oxide particles is coated with a silicon compound, The oxide constituting the above oxide particles is cerium oxide. The silicon compound described above can change the color characteristics of the oxide particles by coating at least a portion of the surface of the oxide particles. The M-OH bond / M-O bond ratio of the above oxide particles is 25% or more and 40% or less. Silicon compound-coated oxide particles, characterized in that, in a dispersion liquid obtained by dispersing the above oxide particles in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 4000 L / (mol·cm) or more.

18. The oxide particles in which the ratio of M-OH bonds contained in the above oxide particles is controlled are oxide particles in which at least a portion of the surface of a single oxide particle, or the surface of an aggregate formed by the aggregation of multiple oxide particles, is coated with a silicon compound. Silicon compound coated oxide particles according to any one of claims 1 to 17, characterized in that the particle size of the oxide particles or aggregates of oxide particles is 1 nm or more and 50 nm or less.

19. Silicon compound coated oxide particles according to any one of claims 1 to 18, characterized in that the silicon compound includes amorphous silicon oxide.

20. Oxide particles composed of iron oxide, The M-OH bond / M-O bond ratio of the above oxide particles is 1% or more and 21% or less. The oxide particles are characterized in that, in a dispersion liquid obtained by dispersing the above oxide particles in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 190 nm to 380 nm is 1000 L / (mol·cm) or more.

21. Oxide particles composed of iron oxide, The M-OH bond / M-O bond ratio of the above oxide particles is 1% or more and 21% or less. Oxide particles characterized in that the average reflectance of the oxide particles for light rays with wavelengths from 780 nm to 2500 nm is 55% or more.

22. Oxide particles composed of cerium oxide, Oxide particles characterized in that the M-OH bond / M-O bond ratio of the oxide particles is 30% or less, and in a dispersion liquid obtained by dispersing the oxide particles in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 3500 L / (mol·cm) or more.

23. Oxide particles composed of cerium oxide, Oxide particles characterized in that the M-OH bond / M-O bond ratio of the oxide particles is 23% or less, and in a dispersion liquid obtained by dispersing the oxide particles in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 4000 L / (mol·cm) or more.

24. Oxide particles composed of cobalt-zinc composite oxide, Oxide particles characterized in that the M-OH bond / M-O bond ratio of the oxide particles is 1% or more and 33% or less, and in a dispersion liquid obtained by dispersing the oxide particles in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 700 L / (mol·cm) or more.

25. Oxide particles composed of silicon-cobalt-zinc composite oxide, Oxide particles characterized in that the M-OH bond / M-O bond ratio of the oxide particles is 13% or more and 40% or less, and in a dispersion liquid obtained by dispersing the oxide particles in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 800 L / (mol·cm) or more.

26. The oxide particles according to any one of claims 20 to 25, characterized in that the primary particle diameter of the oxide particles is 100 nm or less.

27. The oxide particles are zinc oxide particles with a primary particle diameter of 50 nm or less. The M-OH bond / M-O bond ratio of the above oxide particles is 18% or less. The oxide particles are characterized in that, in a dispersion liquid obtained by dispersing the above oxide particles in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 500 L / (mol·cm) or more.

28. The oxide particles are zinc oxide particles with a primary particle diameter of 50 nm or less. The M-OH bond / M-O bond ratio of the above oxide particles is 15% or less. The oxide particles are characterized in that, in a dispersion liquid obtained by dispersing the above oxide particles in a dispersion medium, the average molar extinction coefficient for light rays with wavelengths from 200 nm to 380 nm is 650 L / (mol·cm) or more.

29. The oxide particles are zinc oxide particles with a primary particle diameter of 50 nm or less. The above oxide particles have an M-OH bond / M-O bond ratio of 14% or less. Oxide particles characterized in that the average reflectance of the oxide particles for light rays with wavelengths from 780 nm to 2500 nm is 65% or more.

30. The oxide particles are zinc oxide particles with a primary particle diameter of 50 nm or less. The above oxide particles have an M-OH bond / M-O bond ratio of 14% or less. In a dispersion liquid in which the above oxide particles are dispersed in a dispersion medium, the oxide particles are characterized in that the transmittance to light with a wavelength of 330 nm is 10% or less, and the average transmittance to light with a wavelength of 380 nm to 780 nm is 90% or more.

31. The oxide particles according to any one of claims 27 to 29, characterized in that the haze value of the oxide particle dispersion obtained by dispersing the above oxide particles in a dispersion medium is 1% or less.

32. A coating or film-like oxide composition characterized by containing oxide particles according to any one of claims 1 to 31.

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