WO2024090211A1 - Particules noires - Google Patents

Particules noires Download PDF

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Publication number
WO2024090211A1
WO2024090211A1 PCT/JP2023/036939 JP2023036939W WO2024090211A1 WO 2024090211 A1 WO2024090211 A1 WO 2024090211A1 JP 2023036939 W JP2023036939 W JP 2023036939W WO 2024090211 A1 WO2024090211 A1 WO 2024090211A1
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black particles
silica
particles
less
structural color
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PCT/JP2023/036939
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Japanese (ja)
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雄介 荒井
敏行 増井
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Ａｇｃ株式会社
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G45/00—Compounds of manganese
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black

Definitions

  • the present invention relates to black particles, and more specifically to transition metal oxide-based black particles.
  • Structural color is a coloring phenomenon resulting from the spectrum of a microstructure close to the wavelength of light. Unlike coloring caused by dyes or pigments, there is no discoloration due to the absorption of ultraviolet light, and the coloring will continue forever unless the microstructure that causes the coloring phenomenon disappears. Materials with such structural coloring properties can achieve vivid coloring without using heavy metals such as mercury or chromium, so they have a small environmental impact and can meet the needs for safety and security, and are expected to be applied to new pigments. In particular, structural coloring materials using silica (silicon dioxide, SiO 2 ), which does not contain components that are harmful to the human body or have a high environmental impact, and has excellent heat resistance, have attracted attention.
  • structural coloring materials using silica including spherical colloidal crystals formed from silica particles of uniform particle size, and structural color films in which silica particles are deposited on the surface of an electrode by electrophoresis (hereafter collectively referred to as structural color silica). These materials are expected to find industrial applications because they can easily produce structural colors by self-arranging silica particles.
  • the color of structurally colored silica is due to Bragg reflection in a colloidal crystal structure in which silica particles are arranged, but it is known that the saturation of the color is reduced by various types of light scattering that occur in addition to Bragg reflection (scattering by particles, multiple scattering on the surface of the bulk, etc.). For this reason, a method is known in which black particles (such as carbon black nanoparticles, graphene, melanin, etc.) are added to primary silica particles in structurally colored silica to remove unnecessary scattered light and increase saturation.
  • black particles such as carbon black nanoparticles, graphene, melanin, etc.
  • Patent Document 1 describes a composite metal oxide mainly composed of Cu, Mn, and Al.
  • Non-Patent Document 1 reports a research example in which heat-resistant, environmentally friendly black particles are applied to structural color silica.
  • Non-Patent Document 2 reports black particles mainly composed of Cu as black particles containing Cu.
  • structurally colored silica which develops structural colors through self-arrangement, has the problem that the bonding strength between primary particles is weak, and the application of external force easily causes the structure to collapse and color to be lost.
  • structurally colored silica can be strengthened by heat treating it at a temperature of 600°C or higher. This is thought to be due to the formation of necks between the primary silica particles, and strength can be further increased by increasing the heat treatment temperature, and according to non-patent document 3, it is known that high structural robustness can be achieved by heat treatment at a temperature of 900°C or higher.
  • Non-Patent Document 1 reports on the change in color development due to heat treatment for structural color silica using carbon black, cobalt black, Fe3O4 , calcium manganate , and lanthanum manganate as black particles.
  • structural color silica to which carbon black and Fe3O4 have been added discolors due to heat treatment at 400°C or higher, and it is reported that calcium manganate, although thermally stable up to 1200°C by itself, discolors when used in structural color silica due to heat treatment at 700°C or higher.
  • the present invention aims to provide black particles that are environmentally friendly, have excellent heat resistance, and have good blackness when used in structural color silica without discoloration even when heat treated at 800°C or higher.
  • transition metal oxides with a double perovskite structure containing strontium, tantalum, and manganese as the main phase can produce novel black particles that are environmentally friendly, heat resistant, and have a high degree of blackness, making them suitable for structural color silica, leading to the completion of the present invention.
  • the present invention relates to the following: (1) Black particles made of a transition metal oxide containing at least strontium, tantalum, and manganese and substantially no chromium, cobalt, or nickel, and having a double perovskite structure as a main phase. (2) The black particles according to (1) above, which are made of a transition metal oxide having a double perovskite structure as a main phase and represented by the general formula ( CaxSr1 -x ) 2TaMnO6 (wherein x is 0 ⁇ x ⁇ 0.7). (3) The black particles according to (1) or (2), wherein the black particles have a lightness index L * value of 25 or less in the CIE1976 L * a * b * color system.
  • the black particles according to (6) above, wherein the black particles in the structural color silica have a number-based cumulative 10% particle diameter D10 of 1.5 ⁇ m or less and a number-based cumulative 50% particle diameter D50 of 3 ⁇ m or less.
  • the present invention can provide black particles that combine environmental friendliness, heat resistance, and blackness.
  • the black particles of the present invention can be used as black particles for structural color silica, which are suitable for improving the color development and strength of structural color silica particles and structural color pigments and coatings that contain structural color silica particles.
  • FIG. 1 is a diagram showing powder X-ray diffraction patterns of the black particles of Examples 1 and 3 to 6.
  • the black particles of the present invention are made of a transition metal oxide that contains at least strontium, tantalum, and manganese, and is substantially free of chromium, cobalt, and nickel, and has a double perovskite structure as its main phase.
  • the transition metal oxide constituting the black particles of the present invention contains at least strontium, tantalum, and manganese.
  • the transition metal oxide has a double perovskite structure ( A2B'B " O6 ) as the main phase of the crystal structure, in which A contains at least strontium, B' contains manganese, B" contains tantalum, and O contains oxygen.
  • the transition metal oxide has the above structure, so that the crystal does not denature at high temperatures, and even when used in structural color silica, it does not react with silica at high temperatures, improving heat resistance, suppressing discoloration even at high temperatures of 800°C or higher, and maintaining blackness.
  • the transition metal oxide constituting the black particles of the present invention may have a double perovskite structure represented by the general formula ( CaxSr1 -x ) 2TaMnO6 (wherein x is 0 ⁇ x ⁇ 0.7).
  • Structural color silica containing black particles made of transition metal oxides containing calcium is prone to neck formation between primary silica particles by heating, so that it is possible to increase the strength at a temperature lower than 800°C.
  • x is preferably 0 ⁇ x ⁇ 0.7, more preferably 0 ⁇ x ⁇ 0.5, and most preferably 0 ⁇ x ⁇ 0.3.
  • the crystal structure is a double perovskite structure
  • the maximum peak in the powder X-ray diffraction pattern is attributable to a double perovskite structure consisting of strontium, tantalum and manganese.
  • the amount of calcium is preferably in a range in which no peaks attributed to Ca2MnTaO6 appear.
  • the fact that the double perovskite structure is the main phase can also be confirmed by the fact that the transition metal oxide contains 80 mol % or more of the double perovskite structure.
  • the black particles of the present invention are desirably composed only of a double perovskite structure containing at least strontium, tantalum, and manganese, but other elements or other phases may be included as long as the crystal structure of the double perovskite structure can be maintained and the desired effect of the present invention is not impaired.
  • Such other elements include, for example, calcium, barium, niobium, antimony, etc.
  • other phases include, for example, Sr 2 Ta 2 O 7 , Ca 2 Ta 2 O 7 , etc.
  • the black particles of the present invention may be inevitably mixed with impurities derived from various raw materials, but do not substantially contain chromium (Cr), cobalt (Co) and nickel (Ni). "Substantially” means excluding the case where they are inevitably contained from other blended components unintentionally. Even if Cr, Co and Ni are contained as impurities, it is preferable that the content of Cr 6+, which is particularly a safety concern, is 10 mass ppm or less. It is also preferable that unreacted residues of the raw materials are not contained as much as possible, and it is particularly preferable that the content of Cr 6+ , which is a safety concern, is 1 mass ppm or less in the black particles.
  • composition and impurity amount of transition metal oxides can be measured by ICP emission spectroscopy, energy dispersive X-ray spectroscopy, X-ray fluorescence analysis, etc.
  • the blackness of the black particles of the present invention is represented by the CIE1976 L * a * b * color system, in which lightness is represented by L * , red to green by a * (positive is reddish, negative is greenish), and yellow to blue by b * (positive is yellowish, negative is blueish), and the smaller L * is and the closer a * and b * are to 0, the better the blackness is.
  • the L * value, a * value and b * value can be calculated from measurements made with a general color difference meter or spectrum measurements made with a visible/ultraviolet spectrophotometer.
  • the black particles of the present invention preferably have a lightness index L * value of 25 or less. If the L * value is 25 or less, when used in structurally colored silica, the arrangement structure of the primary silica particles is maintained within a range in which the structural color can be expressed, while unnecessary scattered light is removed, thereby improving saturation.
  • the L * value is more preferably 24 or less, even more preferably 23 or less, particularly preferably 21 or less, even more preferably 20 or less, and most preferably 19 or less.
  • the a * and b * values of the black particles of the present invention are preferably -3 or more and 3 or less.
  • cool colors such as blue and green are suppressed, and when they are 3 or less, warm colors such as red and yellow are suppressed.
  • the a * and b * values are more preferably -2.8 or more, even more preferably -2.6 or more, and more preferably 2.8 or less, and even more preferably 2.6 or less.
  • the achromaticity C * calculated from the a * and b * values by the following formula (1) is preferably 0 to 5, more preferably 0 to 4, particularly preferably 0 to 3, and most preferably 0 to 2.
  • C * represents the degree of coloring, with C * of 0 being achromatic and the higher C * being the greater the coloring. If C * exceeds 5, the blackness tends to be insufficient.
  • C * ⁇ (a * ) 2 + (b * ) 2 ⁇ 1/2 ... (1)
  • the black particles of the present invention can be produced by a method of mixing raw materials in a wet or dry manner, firing the raw materials, and then crushing them. From the viewpoint of production costs, it is preferable to produce the black particles by a method of mixing raw materials, firing, and pulverizing them, but the black particles of the present invention have a feature that a single-phase double perovskite structure can be easily obtained by dry mixing and then firing.
  • strontium compound, calcium compound, tantalum compound, and manganese compound used as starting materials may be in the form of their respective oxides, hydroxides, carbonates, etc.
  • strontium compounds include SrCO3 , SrO, Sr(OH) 2 , etc.
  • calcium compounds include CaCO3 , CaO, Ca(OH) 2 , etc.
  • tantalum compounds include Ta2O5 , Ta2O5 ( H2O ) 5 , Ta2 ( OC2H5 ) 10 , etc.
  • manganese compounds include Mn2O3 , MnO2 , Mn( OH ) 2 , etc.
  • the starting materials are weighed out to obtain a predetermined composition in a stoichiometric ratio.
  • the starting materials are then mixed.
  • Mixing can be performed by a known method.
  • a wet mill using a grinding media such as a wet ball mill, wet bead mill, wet sand grinder mill, or media stirring mill, or a wet mill without grinding media such as a stirring mill, disk mill, in-line mill, or jet mill, can be used.
  • a dry disperser such as a dry jet mill, hammer mill, dry bead mill, impeller mill, or dry ball mill can be used.
  • the mixing time and number of passes can be set appropriately according to the capacity of the equipment, and when using grinding media, the media diameter and media packing rate can also be adjusted appropriately.
  • grinding media such as alumina and zirconia can be used.
  • an agate mortar instead of mixing with a grinder, an agate mortar can be used for simplicity.
  • any solvent can be used as the dispersion medium.
  • examples include water and alcohol, but it is preferable to use water.
  • a dispersant may be added during wet mixing, and for example, a polymer dispersant such as a polyoxyalkylene-based or polycarboxylic acid-based dispersant may be used.
  • the amount of dispersant added may be adjusted as appropriate.
  • the mixture may be filtered, dried, spray-dried, etc. as necessary. Granulation or molding may also be performed as necessary.
  • the mixed raw materials are fired using known equipment.
  • firing equipment include electric furnaces and rotary kilns.
  • the firing is preferably carried out in an air atmosphere at a temperature in the range of 1200 to 1500°C, and can be adjusted as appropriate based on the results of powder X-ray diffraction and particle size distribution measurement of the particles after firing and crushing.
  • the firing temperature is preferably 1200°C or higher, more preferably 1250°C or higher, even more preferably 1300°C or higher, particularly preferably 1350°C or higher, and most preferably 1400°C or higher.
  • it is preferably 1500°C or lower, and most preferably 1450°C or lower.
  • the firing time can be set appropriately, but firing for a period between 3 and 12 hours makes it easier to obtain a transition metal oxide having the aforementioned crystalline phase.
  • the firing time is preferably 3 hours or more, more preferably 4 hours or more, particularly preferably 5 hours or more, and most preferably 6 hours or more.
  • the firing time is preferably 12 hours or less, more preferably 11 hours or less, even more preferably 10 hours or less, particularly preferably 9 hours or less, and most preferably 8 hours or less.
  • the black particles after firing may be crushed or pulverized as necessary.
  • the aforementioned dry grinder or ultrasonic disperser is used for crushing and pulverization. After crushing and pulverization, the particles can be classified as necessary to obtain the desired particle size.
  • the size of the black particles of the present invention is preferably in the range of 10 nm to 20 ⁇ m in particle diameter.
  • the particle diameter is 10 nm or more, it is easy to mix uniformly with the silica primary particles when forming the structural color silica, and the effect of improving saturation relative to the amount added is good.
  • the particle diameter is 20 ⁇ m or less, it is unlikely that the desired effect will not be obtained because the particles are not included in the structure of the structural color silica, and the effect of reducing the angle dependency of color development can be expected by moderately disturbing the arrangement of the silica primary particles.
  • the particle diameter is more preferably 40 nm or more, even more preferably 60 nm or more, even more preferably 80 nm or more, particularly preferably 100 nm or more, and more preferably 18 ⁇ m or less, even more preferably 16 ⁇ m or less, and particularly preferably 14 ⁇ m or less.
  • the black particles of the present invention preferably have a cumulative 50% particle diameter D 50 based on volume of 5 ⁇ m or less.
  • the 50% particle diameter D 50 is 5 ⁇ m or less, the desired effect is rarely not obtained because the particles are not included in the structure of the structural color silica when forming the structural color silica, and the effect of reducing the angle dependency of color development can be expected by moderately disturbing the arrangement of the primary silica particles.
  • the 50% particle diameter D 50 is preferably 100 nm or more, and when the 50% particle diameter D 50 is 100 nm or more, the effect of improving saturation relative to the amount added is good.
  • the 50% particle diameter D 50 is preferably 100 nm to 5 ⁇ m
  • the lower limit is more preferably 125 nm or more, even more preferably 150 nm or more, and particularly preferably 175 nm or more
  • the upper limit is more preferably 4 ⁇ m or less, more preferably 3.5 ⁇ m or less, and particularly preferably 3 ⁇ m or less.
  • the black particles of the present invention preferably have a cumulative 10% particle diameter D10 based on volume of 2 ⁇ m or less. If the 10 % particle diameter D10 is 2 ⁇ m or less, the occurrence of color unevenness between particles due to the number of black particles per structural color silica becoming non-uniform when forming structural color silica can be suppressed.
  • the 10% particle diameter D10 is preferably 20 nm or more, and if the 10% particle diameter D10 is 20 nm or more, it is easy to mix uniformly with the silica primary particles when synthesizing structural color silica.
  • the 10% particle diameter D10 is preferably 20 nm to 2 ⁇ m
  • the lower limit is more preferably 50 nm or more, even more preferably 75 nm or more, and particularly preferably 100 nm or more
  • the upper limit is more preferably 1.8 ⁇ m or less, more preferably 1.6 ⁇ m or less, and particularly preferably 1.4 ⁇ m or less.
  • the black particles of the present invention preferably have a cumulative 90% particle diameter D 90 based on volume of 1 ⁇ m to 15 ⁇ m.
  • the 90% particle diameter D 90 is 1 ⁇ m or more, the effect of improving saturation relative to the amount added is good, and when it is 15 ⁇ m or less, it is unlikely that the particles will not be incorporated into the structure of the structural color silica and the desired effect will not be obtained, and the effect of reducing the angle dependency of color development can be expected by moderately disturbing the arrangement of the primary silica particles.
  • the 90% particle diameter D 90 is more preferably 2 ⁇ m or more, even more preferably 3 ⁇ m or more, particularly preferably 4 ⁇ m or more, and more preferably 14 ⁇ m or less, even more preferably 13 ⁇ m or less, and particularly preferably 12 ⁇ m or less.
  • the particle size and particle size distribution of the black particles can be measured using a known particle size distribution measuring device.
  • An example of a particle size distribution measuring device is Microtrac's "MT3000II" (product name).
  • the black particles of the present invention are preferably used for structural color silica.
  • the structural color silica containing the black particles of the present invention has excellent heat resistance, and does not discolor even when heat-treated at a high temperature of 800° C. or more, and can improve the color development of the structural color silica.
  • the structural color silica is composed of primary silica particles and the black particles of the present invention.
  • the primary silica particles are preferably made of silica (SiO 2 ) and have a spherical shape.
  • the sphericity which is a measure of how close the shape of an object is to a perfect sphere, is preferably 80% or more.
  • the spherical shape of the primary silica particles makes it possible to realize a periodic structure sufficient to express structural colors through aggregation, self-arrangement, etc.
  • the sphericity is more preferably 83% or more, further preferably 85% or more, and particularly preferably 87% or more. The higher the sphericity, the more preferable it is, and 100% is the most preferable.
  • the sphericity is determined by measuring 100 of the primary silica particles constituting one particle of any structural color silica in a photographic projection obtained by photographing structural color silica with a scanning electron microscope (SEM). For each of the 100 primary silica particles, the circumscribed circle diameter (DL) and the inscribed circle diameter (DS) are measured, and the ratio (DS/DL) of the inscribed circle diameter (DS) to the circumscribed circle diameter (DL) is calculated, and the average value expressed as a percentage is taken as the sphericity. If the number of primary silica particles constituting one particle of structural color silica is less than 100, the particle diameter of all primary silica particles visible in the SEM image of one particle of structural color silica is measured to determine the sphericity.
  • the primary silica particles constituting the structural color silica of the present invention must be selected to have an appropriate particle size depending on the desired color development, but in order to achieve color development in the visible light range, the particle size is preferably in the range of 100 to 1000 nm. If the particle size is 100 nm or more, color development due to light interference, diffraction, scattering, etc. based on the arrangement of the primary silica particles is obtained, and if it is 1000 nm or less, the particle size of the structural color silica is easy to adjust.
  • the particle size of the primary silica particles is more preferably 110 nm or more, even more preferably 120 nm or more, and particularly preferably 130 nm or more.
  • the particle size is more preferably 900 nm or less, even more preferably 800 nm or less, and particularly preferably 700 nm or less.
  • the cumulative 50% particle size D 50 based on the number of primary silica particles in the structural color silica should be selected from particle sizes appropriate for the desired color development.
  • the ratio D 50 / ⁇ d of D 50 [nm] to the dominant wavelength ⁇ d [nm] of the desired color development of the structural color silica is preferably in the range of 0.30 to 0.60.
  • D 50 / ⁇ d is more preferably 0.33 or more, even more preferably 0.34 or more, particularly preferably 0.35 or more, and more preferably 0.55 or less, even more preferably 0.50 or less, and particularly preferably 0.47 or less.
  • the cumulative 10% particle diameter D10 based on the number of primary silica particles in the structural color silica is preferably 100 nm or more from the viewpoint of preventing adverse effects on the human body.
  • the particle size distribution of the primary silica particles in the structural color silica can be measured using a particle size distribution meter or by observation with a SEM.
  • An example of a particle size distribution meter is "Nanotrack" (product name) by Microtrack.
  • the particle size distribution is determined by measuring 100 of the primary silica particles constituting one particle of any structural color silica by SEM observation.
  • the particle size distribution is determined by measuring the particle size of all primary silica particles visible in the SEM image of one particle of structural color silica.
  • the range of the particle size (D 50 ) of the primary silica particles for obtaining a desired color is as follows.
  • the particle size of the primary silica particles constituting the structural color silica is preferably in the range of 150 to 235 nm, more preferably in the range of 180 to 230 nm, and even more preferably in the range of 190 to 225 nm.
  • the particle size of the primary silica particles that make up the structural color silica is in the range of 235 to 265 nm.
  • the particle size is more preferably in the range of 240 to 260 nm, and even more preferably in the range of 245 to 255 nm.
  • the particle diameter of the primary silica particles that make up the structural color silica is in the range of 265 to 320 nm.
  • the particle diameter is more preferably in the range of 270 to 315 nm, and even more preferably in the range of 275 to 310 nm.
  • the cumulative 50% particle diameter D 50 based on the number of black particles in the structural color silica is preferably 3 ⁇ m or less. If the 50% particle diameter D 50 is 3 ⁇ m or less, the desired effect is rarely not obtained because the particles are not included in the structure of the structural color silica, and the effect of reducing the angle dependency of color development can be expected by moderately disturbing the arrangement of the primary silica particles.
  • the 50% particle diameter D 50 is preferably 50 nm or more, and if the 50% particle diameter D 50 is 50 nm or more, the effect of improving saturation relative to the amount added is good.
  • the 50% particle diameter D 50 is preferably 50 nm to 3 ⁇ m
  • the lower limit is more preferably 75 nm or more, even more preferably 100 nm or more, and particularly preferably 125 nm or more
  • the upper limit is more preferably 2.8 ⁇ m or less, more preferably 2.6 ⁇ m or less, and particularly preferably 2.4 ⁇ m or less.
  • the cumulative 10% particle diameter D10 based on the number of black particles in the structural color silica is preferably 1.5 ⁇ m or less.
  • the 10% particle diameter D10 is preferably 20 nm or more, and when the 10% particle diameter D10 is 20 nm or more, it is easy to mix uniformly with the silica primary particles when synthesizing the structural color silica.
  • the 10% particle diameter D10 is preferably 20 nm to 1.5 ⁇ m
  • the lower limit is more preferably 50 nm or more, even more preferably 75 nm or more, and particularly preferably 100 nm or more
  • the upper limit is more preferably 1.2 ⁇ m or less, more preferably 0.8 ⁇ m or less, and particularly preferably 0.4 ⁇ m or less.
  • the black particles have a cumulative 10% particle size D10 based on the number of particles in the structural color silica of 1.5 ⁇ m or less, and a cumulative 50% particle size D50 of 3 ⁇ m or less.
  • the cumulative 90% particle diameter D 90 based on the number of black particles in the structural color silica is preferably 400 nm to 20 ⁇ m. If the 90% particle diameter D 90 is 400 nm or more, the effect of improving saturation relative to the amount added is good, and if it is 20 ⁇ m or less, it is unlikely that the desired effect will not be obtained because it is not incorporated into the structure of the structural color silica, and the effect of reducing the angle dependency of color development can be expected by moderately disturbing the arrangement of the primary silica particles.
  • the 90% particle diameter D 90 is more preferably 520 nm or more, even more preferably 650 nm or more, particularly preferably 800 nm or more, and more preferably 12 ⁇ m or less, even more preferably 10 ⁇ m or less, and particularly preferably 8 ⁇ m or less.
  • the particle size distribution of the black particles in the structural color silica can be measured by a particle size distribution meter or SEM observation, as described above.
  • SEM observation the particle size of 100 randomly selected black particles is measured to determine the particle size. If the number of black particles is small compared to the number of primary silica particles and it is difficult to confirm 100 black particles in SEM observation, it is sufficient to measure a possible number of particles of 10 or more for convenience. If no black particles are found on the surface of the structural color silica, the structural color silica may be broken by applying an external force to form a fracture surface, and the black particles present on the fracture surface may be measured. The particle size is determined by the diameter of the circumscribed circle of the particle.
  • the ratio s/d of the cumulative 10% particle diameter s ( D10 ) of the black particles to the 50% particle diameter d ( D50 ) of the silica primary particles is preferably 0.5 or less. If the size of the black particles is too large relative to the silica primary particles, the arrangement of the structural color silica is too much disrupted, and there is a risk that the structural color will not be generated.
  • the ratio s/d is 0.5 or less, the black particles are dispersed in the structure without disrupting the arrangement of the structural color silica, and unnecessary scattered light can be efficiently suppressed to improve saturation.
  • the ratio s/d is more preferably 0.45 or less, more preferably 0.4 or less, and from the viewpoint of the efficiency of absorbing scattered light, it is preferably 0.01 or more, more preferably 0.05 or more.
  • N Si of primary silica particles present on the surface of any 10 pieces of structural color silica and the average number N BL of black particles satisfy the following relational formula (2).
  • N Si ⁇ 10 ⁇ (a/d) 2 ⁇ N BL (2) (In formula (2), d is the cumulative 50% particle diameter D50 based on the number of silica primary particles, and a is the cumulative 50% particle diameter D50 based on the number of black particles.)
  • the content ratio of primary silica particles to black particles in the structural color silica is preferably 50:50 to 98:2, calculated as a mass ratio of oxides.
  • the ratio is more preferably 55:45 to 95:5, more preferably 60:40 to 90:10, and particularly preferably 65:35 to 85:15, for primary silica particles to black particles.
  • Structural color silica can be produced, for example, by forming colloidal crystals or by forming an electrodeposition film using an electrodeposition method.
  • One method for forming colloidal crystals is to disperse an aqueous phase containing dispersed silica primary particles and black particles in a non-water-soluble organic liquid to form an oil-in-water emulsion, and then to remove the dispersant by repeating drying and solvent replacement one or more times to obtain structurally colored silica in which the primary particles are aggregated.
  • the primary particles self-align in the aggregation process to form a colloidal crystal structure with a periodic structure, which produces the structural color.
  • an electrodeposited film is prepared according to a conventional method, and then the film is peeled off to obtain structurally colored silica.
  • a sol solution in which primary silica particles are dispersed in a water-soluble solvent is mixed with black particles to prepare a primary particle dispersion, and then the anode and cathode are immersed in an electrolytic cell that stores the primary particle dispersion, and direct current electrolysis is performed in this state.
  • the electrodeposited film is peeled off from the anode, and a structurally colored silica thin film is obtained by crushing or cutting. When producing particulate structurally colored silica by electrodeposition, the obtained structurally colored silica thin film can be crushed and classified.
  • Examples 1 to 5 are examples, and Examples 6 to 8 are comparative examples.
  • Example 1 The starting materials shown in Table 1 were weighed out in a stoichiometric ratio, dry-mixed in an agate mortar for 30 minutes, and then placed in an alumina boat and fired in an electric furnace at 1400° C. for 6 hours in air. After firing, the mixture was coarsely crushed in the agate mortar for about 1 minute to obtain black particles.
  • the obtained black particles were used to prepare structurally colored silica.
  • 1.0 g of a dispersion sol of primary silica particles having a cumulative 50% particle diameter D50 of 220 nm based on volume and 0.1 g of the black particles prepared above were mixed with pure water, and the mixture was subjected to ultrasonic treatment for 3 minutes using an ultrasonic cleaner (US-13KS manufactured by SND Co., Ltd.)
  • the mixture was gently dropped onto a PFA petri dish using a micropipette, and was left to stand until the solvent was completely evaporated and the dish was dried.
  • the obtained dried body was divided into two, and one was heat-treated at 800° C. for 2 hours in an air atmosphere to obtain structurally colored silica.
  • Example 2 The preparation of structurally colored silica was carried out in the same manner as in Example 1, except that the ultrasonic treatment time was 30 minutes.
  • Examples 3 to 6 The same procedure as in Example 1 was repeated, except that the starting materials were changed as shown in Table 1 to obtain black particles.
  • Example 7 The starting materials shown in Table 1 were weighed out in a stoichiometric ratio, dry-mixed in an agate mortar for 30 minutes, then placed in an alumina boat and fired in an electric furnace in air at 1200° C. for 6 hours. After firing, the mixture was coarsely crushed in the agate mortar for about 5 minutes to obtain black particles. Using the obtained black particles, structurally colored silica was obtained in the same manner as in Example 1.
  • Example 8 The starting materials shown in Table 1 were weighed out in a stoichiometric ratio, dry-mixed in an agate mortar for 30 minutes, then placed in an alumina boat and fired in an electric furnace in air at 1000° C. for 10 hours. After firing, the mixture was coarsely crushed in the agate mortar for about 5 minutes to obtain black particles. Using the obtained black particles, structurally colored silica was obtained in the same manner as in Example 1.
  • Black particle size distribution ( D10 , D50 , D90 )
  • the particle size distribution was measured using a Microtrac MT3000II.
  • the black particles were placed in pure water and dispersed for 3 minutes using an ultrasonic cleaner (US-13KS manufactured by SND Corporation) for Examples 1 and 3 to 8, and for 30 minutes using an ultrasonic cleaner for Example 2, and then measurements were performed for 30 seconds with a particle refractive index of 2.16 and a solvent refractive index of 1.333. From this, the cumulative 10% particle size D 10 , cumulative 50% particle size D 50 and cumulative 90% particle size D 90 on a volume basis were determined. The results are shown in Table 1.
  • XRD pattern of black particles The black particles of Examples 1 and 3 to 6 were subjected to X-ray diffraction.
  • X-ray diffraction an Ultima IV manufactured by Rigaku Corporation was used, and the measurement conditions were Cu-K ⁇ radiation, tube voltage 40 kV, tube current 40 mA, scanning speed 2 ⁇ : 6°/min, sampling width 0.02°. The results are shown in Figure 1.
  • the peaks indicated by the symbol “ ⁇ ” are diffraction peaks derived from a double perovskite structure ( Sr2MnTaO6 ) consisting of strontium, tantalum, and manganese
  • the peaks indicated by the symbol “ ⁇ " are diffraction peaks derived from a double perovskite structure ( Ca2MnTaO6 ) consisting of calcium, tantalum, and manganese.
  • the black particles of Examples 1 to 5 are excellent in environmental friendliness since they do not contain Cr, Co, or Ni, which are harmful to the environment and human body, and are excellent in heat resistance since they are black particles produced by firing at 1400°C in the atmosphere, and have a good blackness with a small lightness L * , which is an index of blackness, of 20 or less.
  • L * which is an index of blackness, of 20 or less.
  • the color change in the structurally colored silica is small even after heat treatment at 800°C, so they are also suitable for increasing strength by heat treatment.
  • they can be finely divided to a particle size distribution suitable for structurally colored silica by a simple crushing treatment in an ultrasonic cleaner for about 3 minutes, so they are suitable as black particles for structurally colored silica.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
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Abstract

La présente invention concerne des particules noires qui sont respectueuses de l'environnement et résistantes à la chaleur, ne sont pas décolorées même lors d'un traitement thermique supérieur ou égal à 800°C lorsqu'elles sont utilisées dans de la silice colorée structurale, et ont une excellente noirceur. Les particules noires selon la présente invention sont composées d'un oxyde de métal de transition qui contient au moins du strontium, du tantale et du manganèse, l'oxyde de métal de transition étant sensiblement exempt de chrome, de cobalt et de nickel, et ayant une structure de pérovskite double en tant que phase principale.
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JP2010037540A (ja) * 2008-07-11 2010-02-18 National Institute For Materials Science 発光ナノシート及びこれを用いた蛍光照明体、太陽電池及びカラーディスプレー。
JP2013224256A (ja) * 2008-05-23 2013-10-31 Ishihara Sangyo Kaisha Ltd 赤外線反射材料及びその製造方法並びにそれを含有した塗料、樹脂組成物
JP2018504344A (ja) * 2014-11-27 2018-02-15 シーリーズ インテレクチュアル プロパティ カンパニー リミティド 構造
WO2018230438A1 (fr) * 2017-06-15 2018-12-20 中島産業株式会社 Matériau d'oxyde mixte noir et son procédé de fabrication
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JP2013224256A (ja) * 2008-05-23 2013-10-31 Ishihara Sangyo Kaisha Ltd 赤外線反射材料及びその製造方法並びにそれを含有した塗料、樹脂組成物
JP2010037540A (ja) * 2008-07-11 2010-02-18 National Institute For Materials Science 発光ナノシート及びこれを用いた蛍光照明体、太陽電池及びカラーディスプレー。
JP2018504344A (ja) * 2014-11-27 2018-02-15 シーリーズ インテレクチュアル プロパティ カンパニー リミティド 構造
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