Dispersion of perovskite particles, and particles

Abstract

To provide a dispersion of particles that exhibits both low photocatalytic activity and high refractive index. [Solution] The dispersion of the present invention comprises perovskite structure particles and an organic solvent, wherein the atomic ratio of zirconium (Zr) to alkaline earth metal (M) (Zr / M) obtained by measuring the particles by X-ray photoelectron spectroscopy is 0.05 or higher, and the spectrum obtained by measuring the particles by infrared spectroscopy contains 2830 cm⁻¹ -1 Intensity I 2830 And, 3500cm -1 Intensity I 3500 The ratio (I 2830 / I 3500 The values ​​are between 0.11 and 0.3.

Description

Technical Field

[0001] The present invention relates to perovskite-structured particles.

[0002] Conventionally, a film with a high refractive index has been formed on a substrate using a coating liquid containing oxide particles with a high refractive index (high refractive index particles). Such films are used, for example, in glasses, lenses, displays, etc. Zirconium oxide particles are known as high refractive index particles. (For example, Patent Document 1).

[0003] Titanium oxide particles are known as materials having a higher refractive index than zirconium oxide particles. However, since titanium oxide particles have photocatalytic activity, they deteriorate the resin in the film. That is, the light resistance of a film containing titanium oxide particles is low. In Patent Document 2, by providing a silica layer on the surface of titanium oxide particles, the photocatalytic activity of the titanium oxide particles is suppressed and the light resistance of the film is increased. Also, in order to disperse titanium oxide particles in a solvent, a silica sol is added during the production of titanium oxide particles separately from the silica layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 2, a silica layer is provided on the surface of titanium dioxide particles to suppress photocatalytic activity, and silica is also added during the manufacturing of titanium dioxide particles to disperse the titanium dioxide in a solvent. Since silica has a lower refractive index than titanium dioxide, the refractive index of titanium dioxide particles containing silica is lower than that of particles made only of titanium dioxide. Furthermore, when preparing the coating solution, it is necessary to treat the titanium dioxide particles with a surface treatment agent in order to disperse them in an organic solvent. The proportion of titanium dioxide particles in the film decreases due to the surface treatment agent, resulting in a lower refractive index of the film. Thus, conventional dispersions could not achieve both low photocatalytic activity and a high refractive index. [Means for solving the problem]

[0006] The inventors have found that by providing zirconium on the surface of perovskite-structured particles and adjusting the ratio of hydrocarbon groups to hydroxyl groups on the particle surface to a specific ratio, it is possible to provide a dispersion of particles that exhibits both low photocatalytic activity and a high refractive index. Specifically, the dispersion of the present invention comprises perovskite-structured particles and an organic solvent, wherein the atomic ratio of zirconium (Zr) to alkaline earth metal (M) (Zr / M), obtained by measuring the particles by X-ray photoelectron spectroscopy, is 0.05 or higher, and the spectrum obtained by measuring the particles by infrared spectroscopy shows a refractive index of 2830 cm⁻¹. -1 Intensity I 2830 And, 3500cm -1 Intensity I 3500 The ratio (I 2830 / I 3500 The values ​​are between 0.11 and 0.3. [Modes for carrying out the invention]

[0007] The dispersion of the present invention comprises perovskite particles and an organic solvent, wherein the atomic ratio R of zirconium (Zr) to alkaline earth metal (M) on the surface of the particles s1(Zr / M) is 0.05 or more. The perovskite-structured particles have a high refractive index. By providing Zr having no photocatalytic activity on the surface of the particles, particles having a low photocatalytic activity and a high refractive index can be realized. By forming a film using a coating solution containing such particles and a binder, a film having both a high refractive index and high light resistance can be formed. R s1 The higher [Zr / M] is, the higher the light resistance of the particles becomes. Therefore, R s1 [Zr / M] is preferably 0.2 or more, more preferably 0.4 or more. On the other hand, R s1 If [Zr / M] is 1 or less, it becomes difficult to generate an oxide of an alkaline earth metal other than the perovskite structure in the particles.

[0008] Also, when the particles are measured by infrared spectrum (IR), the intensity I -1 at 2830 cm 2830 and the intensity I -1 at 3500 cm 3500 The ratio (I 2830 / I 3500 ) is 0.11 to 0.3. Thereby, the particles are easily dispersed in an organic solvent or a binder, and the amount of the surface treatment agent required for forming a film is reduced. In a film with less surface treatment agent, the proportion of particles is high and the refractive index is high. Here, since 2830 cm -1 is attributed to C-H stretching vibration, the higher the intensity I 2830 , the larger the number of carbon atoms on the particle surface and the higher the hydrophobicity of the particles. Also, since 3500 cm -1 is attributed to O-H stretching vibration, the higher the intensity I 3500 , the larger the number of OH groups on the particle surface and the higher the hydrophilicity. The smaller the particle size, the more difficult it is for the particles to scatter light, and they can be suitably used for a high refractive index film. When the intensity ratio (I 2830 / I 3500 ) is less than 0.11, the hydrophobicity of the particles is low and the particles cannot be dispersed in an organic solvent. Also, when the intensity ratio (I 2830 / I 3500 ) is greater than 0.3, although the reason is unknown, the particles aggregate and the particle size becomes large. The larger the particle size, the easier it is to scatter light.

[0009] Alkaline earth metals readily occupy the A-site of the perovskite structure (ABO3). Examples of alkaline earth metals include Be, Mg, Sr, Ba, and Ra. In particular, Mg, Sr, and Ba readily occupy the A-site. The alkaline earth metal content of the particles is preferably 40-70% by weight in terms of MO. When the alkaline earth metal content is within this range, the particles tend to maintain their perovskite structure. The alkaline earth metal content of the particles is more preferably 50-70% by weight in terms of MO.

[0010] Zirconium (Zr) readily enters the B site of the perovskite structure (ABO3). From the viewpoint of suppressing the photocatalytic activity of the particles, the zirconium content of the particles is preferably 3% by weight or more, more preferably 10% by weight or more, and even more preferably 20% by weight or more, in terms of ZrO2. On the other hand, in order to easily maintain the perovskite structure of the particles, the zirconium content of the particles is preferably 60% by weight or less, and more preferably 50% by weight or less, in terms of ZrO2.

[0011] Furthermore, from the viewpoint of suppressing the photocatalytic activity of particles, the molar ratio R of zirconium (Zr) to alkaline earth metal (M) in the particles is considered. p (Zr / M) is preferably 0.05 or higher, more preferably 0.2 or higher, and even more preferably 0.4 or higher.

[0012] It is preferable that the particles contain titanium (Ti). Titanium increases the refractive index of the particles. The titanium content of the particles is preferably 5% by weight or more, and more preferably 10% by weight or more, in terms of TiO2. On the other hand, from the viewpoint of suppressing the photocatalytic activity of the particles, the titanium content of the particles is preferably 32% by weight or less, more preferably 30% by weight or less, and even more preferably 25% by weight or less, in terms of TiO2. The titanium content of the particles is even more preferably 20% by weight or less, in terms of TiO2.

[0013] If the particles contain titanium (Ti), the molar ratio R p The (Zr / M) ratio is preferably 0.8 or less, and more preferably 0.6 or less. By lowering this molar ratio, the titanium content of the particles can be increased.

[0014] Furthermore, if the particles contain titanium (Ti), the molar ratio R p (Zr / M) and atomic ratio R s1 (R ratio with Zr / M) p (Zr / M)〕 / 〔R s1 (Zr / M) is preferably 1 or less. This increases the amount of zirconium unevenly distributed on the particle surface.

[0015] When particles contain titanium, the less titanium there is on the particle surface, the lower the photocatalytic activity of the particles and the higher the light resistance of the film. The amount of titanium on the particle surface can be measured by X-ray photoelectron spectroscopy. When particles are measured by X-ray photoelectron spectroscopy, the atomic ratio R of the number of titanium atoms (Ti) to the number of alkaline earth metal atoms (M) is... s2 (Ti / M) is preferably 0.75 or less, more preferably 0.6 or less, and even more preferably 0.5 or less. Also, for the same reason, R s3 (Ti / Zr) is preferably 7 or less, more preferably 3 or less, and even more preferably 2 or less. s3 (Ti / Zr) is more preferably 1.5 or less.

[0016] The crystallite size of the particles is preferably 2 nm or larger, and more preferably 5 nm or larger. The larger the crystallite size, the easier it is for the particles to maintain a perovskite structure. On the other hand, the smaller the crystallite size, the easier it is for the film haze to be lower. Therefore, the crystallite size of the particles is preferably 50 nm or smaller, and more preferably 30 nm or smaller.

[0017] The fewer crystals or amorphous materials other than the perovskite structure (hereinafter, crystals or amorphous materials other than the perovskite structure are referred to as impurities) there are in the particle, the higher the refractive index tends to be. The amount of impurities in the particle can be determined by measuring the particle after heating using X-ray diffraction (XRD) and analyzing the peaks other than the perovskite structure. Amorphous impurities also crystallize upon heating, making them detectable by XRD. Specifically, the particle heated to 500°C is measured by XRD, and the peak with the highest intensity that is attributed to something other than the perovskite structure (I) is identified. i ) and the intensity of the main peak of the perovskite structure (I p) is determined. If the amount of impurities is small, the ratio of peak intensities [I i / I p The ratio of peak intensities decreases. In other words, the smaller the ratio of peak intensities, the smaller the amount of impurities in the particles before heating. The ratio of peak intensities is preferably 0.1 or less, more preferably 0.07 or less, and even more preferably 0.05 or less.

[0018] When the average particle size (D50) of a dispersion is 100 nm or less, the particles scatter light poorly. Films formed using such particles exhibit low haze. Such particles are suitable for optical applications. Furthermore, particles with a D50 of 2 nm or more are easily dispersed in organic solvents. The average particle size is measured by dynamic light scattering. D50 is the median value of the particle size distribution obtained by measuring the dispersion using dynamic light scattering.

[0019] Furthermore, it is preferable that D90 be 100 nm or less. This makes it less likely for the particles to scatter light. D90 is the particle size at which 90% of the particles have a D90 or smaller dimension in the particle size distribution obtained by measuring the dispersion using dynamic light scattering.

[0020] As the ratio of average particle diameter (D50) to crystallite diameter (average particle diameter [D50] / crystallite diameter) decreases from 0.7 to 0.5 to 0.3, the number of crystallites constituting the particle decreases. As a result, the gaps between crystallites within the particle decrease, the particle density increases, and the refractive index of the particle tends to increase. Also, the haze of the film tends to decrease. Since particles with this ratio less than 0.1 are difficult to prepare, the lower limit of this ratio can be said to be 0.1.

[0021] The higher the particle refractive index, the higher the refractive index of the film tends to be. A particle refractive index of 1.8 or higher is preferred, 1.9 or higher is more preferred, and 2 or higher is even more preferred. A particle refractive index of 2.15 or higher is even more preferred.

[0022] Weight C after heating particles to 200°C 200 And the weight C after heating the particles to 1000°C 1000 Weight change rate (C 200 -C 1000 ) / C 200The ratio is preferably 0.15 or less, more preferably 0.1 or less, and even more preferably 0.09 or less. The lower the weight change rate, the less organic compounds such as surface treatment agents are present in the particles.

[0023] The solvent can be selected according to the transport method, the solvent used in the coating solution, and the coating film conditions. Examples include organic solvents such as alcohols, ethers, ketones, alkanes, and aromatic hydrocarbons (toluene, etc.). The solvent may also contain water. By treating the particles with a surface treatment agent, the particles become more easily dispersed in highly hydrophobic solvents such as aromatic hydrocarbons. The IR intensity ratio of the particles (I 2830 / I 3500 Since the ratio is 0.11 or higher, the amount of surface treatment required to disperse particles in highly hydrophobic solvents can be reduced. Particles without surface treatment agents are easily dispersed in alcohols and ethers (especially propylene glycol monomethyl ether [PGM], methanol, methyl cellosolve, etc.). Furthermore, as the proportion of organic solvent in the solvent increases to 50% by weight or more, 70% by weight or more, 90% by weight or more, 95% by weight or more, and 98% by weight or more, the dispersion becomes easier to use in the manufacture of coating solutions containing highly hydrophobic resins.

[0024] Next, the method for producing the particles will be described. Step 1: Prepare an alkyl cellosolve solution of an alkaline earth metal hydroxide. Step 2: Dehydrate the alkyl cellosolve solution. Step 3: Add zirconium alkoxide to the alkyl cellosolve solution. Step 4: Add a solvent containing water to the alkyl cellosolve solution. Step 5: Age the alkyl cellosolve solution at 20°C or higher. Each step will be described in detail below.

[0025] <First step> In this process, an alkyl cellosolve solution of alkaline earth metal hydroxide is prepared. The alkyl cellosolve interacts with the alkaline earth metal hydroxide. Through this interaction, the alkaline earth metal hydroxide dissolves in the alkyl cellosolve. The more the dissolution progresses (the better the dissolution), the smaller the particle size becomes. The fewer carbon atoms in the hydrocarbon group of the alkyl cellosolve, the easier the interaction occurs. The number of carbon atoms is preferably 4 or less, and more preferably 2 or less. Methyl cellosolve is preferred as the alkyl cellosolve. Furthermore, irradiating the alkyl cellosolve solution with ultrasound makes it easier to dissolve the alkaline earth metal hydroxide. Using alkaline earth metal alkoxides instead of alkaline earth metal hydroxides can reduce the particle size, but it increases the cost.

[0026] <Second process> In this step, water is removed from the alkyl cellosolve solution (i.e., the alkyl cellosolve solution is dehydrated). Water is generated when alkaline earth metal hydroxides and alkyl cellosolve interact. Removing this water promotes the interaction. When dehydrating, the higher the temperature of the alkyl cellosolve solution, the easier it is for the alkaline earth metal hydroxides to interact with the alkyl cellosolve. When dehydrating, the temperature of the alkyl cellosolve solution is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher. While higher temperatures facilitate dehydration, excessively high temperatures may cause bumping. To prevent bumping, this temperature is preferably 90°C or lower.

[0027] The longer the dewatering time, the more water can be removed, thus promoting interaction. Therefore, a dewatering time of 10 minutes or more is preferable, and 30 minutes or more is more preferable. On the other hand, if the dewatering time is too long, the production efficiency is low. Efficiency improves in the order of 10 hours or less, 5 hours or less, and 3 hours or less. Also, the longer the dewatering time, the less likely alkaline earth metal hydroxides are to remain undissolved. The less undissolved material there is, the higher the yield. The dewatering time may be set considering the amount of undissolved material. For example, if dewatering is performed so that the amount of undissolved material is less than 40% of the raw material, the particle yield will be 60% or more. The amount of undissolved material is preferably less than 30%, and more preferably less than 25%.

[0028] Dehydration methods include (vacuum) distillation and methods using adsorbents such as silica gel and zeolite. When (vacuum) distillation is performed, the longer the distillation time, the greater the amount of alkaline earth metal hydroxide dissolved. Therefore, it is preferable to distill for 30 minutes or more.

[0029] The lower the water content of the alkyl cellosolve solution after dehydration, the less likely impurities are to be generated when alkoxides are added. Therefore, this water content is preferably less than 1% by weight, more preferably 0.8% by weight or less, and even more preferably 0.55% by weight or less.

[0030] It is preferable to separate undissolved compounds from the alkyl cellosolve solution after dehydration. Undissolved alkaline earth metal hydroxides react with substances in the air (such as CO2) to produce alkaline earth metal salts (such as carbonates). These alkaline earth metal salts become impurities. By promoting the dissolution of hydroxides in the first step, the amount of impurities can be reduced. Separation methods include filtration and decantation. The alkyl cellosolve solution may be centrifuged before decantation.

[0031] <Third process> In this step, zirconium alkoxide is added to the alkyl cellosolve solution. It is preferable to pre-allocate the concentration of alkaline earth metals in the alkyl cellosolve solution to 10% by weight or more. When this concentration is 10% by weight or more, alkaline earth metals and metal elements react more uniformly with the zirconium alkoxide in the alkyl cellosolve solution, making it less likely for compounds other than perovskite structures (alkaline earth metal compounds, metal element compounds, or zirconium compounds, etc.) to form after maturation. On the other hand, the lower the concentration, the less likely impurities are to form. Therefore, this concentration is preferably 40% by weight or less, more preferably 30% by weight or less, and even more preferably 20% by weight or less. The concentration of alkaline earth metals can be adjusted in any step prior to this step. If (vacuum) distillation is chosen as the method of concentration adjustment, heating, dehydration, and concentration adjustment (concentration) can be performed simultaneously. That is, the number of steps can be reduced. If the (vacuum) distillation time is too long, the concentration of alkaline earth metals in the alkyl cellosolve solution becomes too high, so 5 hours or less is preferable. The (reduced pressure) distillation time can be set considering factors such as the distillation temperature, the concentration of alkaline earth metals, and the amount of alkyl cellosolve solution. Examples of zirconium alkoxides include n-propyl zirconate, n-butyl zirconate, zirconium tetra-t-butoxide, zirconium tetraacetylacetonate, zirconium tetraoctoxide, and zirconium tetradecoxide. Among these, n-butyl zirconate is preferred, as it facilitates the dispersion of particles in organic solvents.

[0032] <Fourth process> In this process, a solvent containing water is added to the alkyl cellosolve solution. This causes the alkoxide to hydrolyze. When preparing particles containing titanium, the alkyl cellosolve solution is pre-soaked with titanium alkoxide. By using n-butyl zirconate as the zirconium alkoxide and titanium isopropoxide as the titanium alkoxide, the particles become more easily dispersed in organic solvents.

[0033] The molar ratio of alkaline earth metal to water in the alkyl cellosolve solution is preferably 6 or higher. A higher molar ratio facilitates the hydrolysis of alkoxides. A molar ratio of 30 or lower is preferable. A lower molar ratio results in more uniform hydrolysis and reduces the likelihood of impurities. Furthermore, the hydrolysis rate can be adjusted by adding a mixed solvent of alcohol and water. This ensures uniform hydrolysis. Uniform hydrolysis reduces the likelihood of impurities. To reduce impurities, the weight ratio of alcohol to water (alcohol / water) is preferably 0.5 to 4.0, and more preferably 1.5 to 3.5.

[0034] <Fifth process> The alkyl cellosolve solution containing alkaline earth metals and zirconium is kept at a temperature of 20°C or higher. This allows the alkyl cellosolve solution to mature, yielding particles with a perovskite structure. This method allows for the production of perovskite particles without a calcination process. Furthermore, maturation of the alkyl cellosolve solution allows for crystallization of the particles in the solvent. In other words, there is no need to remove the particles from the solvent for crystallization. Therefore, there is no need to redisperse the particles in the solvent during coating and liquefaction, reducing the number of manufacturing steps. Also, maturation tends to result in a more uniform average particle size. If the maturation time is below 20°C, it is difficult to obtain the energy necessary for crystallization, resulting in a longer maturation time and lower productivity. Maintaining the temperature above 20°C for a longer period reduces crystal defects in the particles and tends to increase thermal stability. Therefore, a maturation time of 6 hours or more is preferable, and 10 hours or more is more preferable. On the other hand, if the time is too long, production efficiency will decrease. For example, efficiency is good if the time is 500 hours or less.

[0035] The coating solution is described below. The coating solution can be prepared using a dispersion of the particles described above. The coating solution contains particles, a binder, and an organic solvent. By forming a film with the coating solution containing the particles described above, the refractive index of the film is increased. A film can be formed by using a coating solution containing a binder. Part of the surface treatment agent may be used as the binder. Examples of binders include monomers before polymerization, oligomers, and polymers after these have been polymerized. Of these, monomers or oligomers are preferred. When curing the film, the film tends to become denser when using a coating solution containing monomers or oligomers rather than a coating solution containing polymers. The organic solvent can be appropriately selected depending on the type of binder added when preparing the coating solution.

[0036] The higher the solid content concentration of the coating solution, the easier it is to form a thick film. Furthermore, the coating solution is easier to handle industrially. Therefore, a concentration of 10% by weight or more is preferred, and 20% by weight or more is more preferred. On the other hand, if the concentration is 50% by weight or less, the viscosity of the coating solution tends to be low. A concentration of 30% by weight or less is preferred.

[0037] If the boiling point of the organic solvent is 80°C or higher, the coating solution can be dried uniformly, resulting in a denser film. A boiling point of 100°C or higher is more preferable. On the other hand, if the boiling point is 200°C or lower, less organic solvent remains, making the film more prone to shrinkage. As a result, the hardness of the film increases. A boiling point of 180°C or lower is more preferable.

[0038] The following describes specific embodiments of the present invention.

[0039] [Example 1] <First step> 100g of barium hydroxide octahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 630g of 2-methoxyethanol (methyl cellosolve) were placed in a 1L beaker and mixed. After mixing, a portion of the barium hydroxide was dissolved at 40°C for 30 minutes while irradiating with ultrasound. This mixed solution was placed in a 2L round-bottom flask along with the solution from the first step, and vacuum distillation was performed using an evaporator. In other words, dehydration and concentration were performed simultaneously. Distillation was carried out at 70°C and 15 hPa for 1 hour.

[0040] <Second process> Next, the mixed solution after distillation was centrifuged to allow undissolved compounds to settle. The supernatant (mixed solution) was then decanted to separate the precipitate (undissolved compounds). The precipitate was white. The centrifugation conditions were 3000 rpm for 15 minutes. The barium concentration of the supernatant (mixed solution immediately before the addition of titanium alkoxide), as measured by ICP-OES, was 15.5% by weight, and the water content was 0.86% by weight.

[0041] <Third process> In a glove box under a nitrogen gas atmosphere, 49.7 g of zirconium tetra-n-toxide (Orgatics® ZA-65, manufactured by Matsumoto Fine Chemical Co., Ltd.; Zr concentration 20.7 wt%) was added to 100 g of the supernatant from the second step and mixed to obtain a mixture.

[0042] <Fourth process> While stirring the mixture at 25°C, a mixed solvent of 60.9 g of methanol and 20.3 g of water was added over 1 minute, and then the mixture was stirred at 25°C for 2 hours.

[0043] <Fifth process> The obtained hydrate gel was heated to 90°C and aged for 48 hours to obtain a particle dispersion. 20 g of this dispersion was dried at 130°C for 1 hour to obtain a particle powder. Using an ultrafiltration membrane, 150 g of the obtained particle dispersion was solvent-replaced with 450 g of denatured alcohol (A-7) and concentrated to a solid content concentration of 13% by weight to obtain an alcohol dispersion of particles.

[0044] The preparation conditions for the dispersion are shown in Table 1, along with those for other examples and comparative examples. The physical properties of the particles and dispersion were measured using the following methods (1) to (5). The measurement results for other examples and comparative examples are shown in Tables 2 and 3.

[0045] (Physical properties of dispersion) (1) XPS(R s1 , R s2 , R s3 ) A 20g dispersion of particles was spread on an evaporating dish and dried in a drying oven at 150°C for 1 hour to prepare the sample for measurement. The sample was measured using an X-ray photoelectron spectroscopy analyzer (KRATOS® ULTRA2, Shimadzu Corporation). The spectral measurement conditions were: X-Ray: 225W, Pass Energy: Wide 160eV, Narrow 80eV, Analysis diameter: 300 × 700 μm, Charge Neutralizer: On. An ArGass Cluster Ion was used as the ion gun, and measurements were performed with an acceleration voltage of 5kV and an etching rate of 0.7nm / min. The binding energy of 1s(CH) was calibrated at 289.0eV. The atomic weights of barium, titanium, and zirconium were calculated from the peak areas of Ba3d, Ti2p, and Zr3d, respectively. Ti2p was observed at 446-467 eV, Ba3d at 768-797 eV, and Zr3d at 175-188 eV. From the measurement results, R s1 , R s2 , R s3 The result was calculated.

[0046] (2) Infrared spectrum (I 2830 / I 3500 ) 20 g of the particle dispersion was spread on an evaporating dish and dried in a dryer at 150°C for 1 hour to obtain a dry powder. The dry powder was mixed with KBr to a concentration of less than 1%, and molded using a micro-tablet molder. This molded product was measured using an FT / IR-6100 in transmission mode, with 50 integration cycles and a wavelength range of 400-4000 cm. -1 The measurement was performed under the following conditions. From the measurement results, I 2830 / I 3500 The result was calculated.

[0047] (3) Particle composition Ba, Ti The sample was added to a mixture of sodium oxide and sodium hydroxide and melted. After dissolving, it was dissolved in dilute hydrochloric acid and diluted with water to prepare the measurement sample. The Ba and Ti content in the measurement sample was measured using ICP-OES (Agilent 5800), and this content was defined as the Ba and Ti content in the particles. From the Ba and Ti content in the particles, the BaO and TiO2 content was determined.

[0048] ·Zr The sample was dried in a mixture of nitric acid and hydrofluoric acid, dissolved in dilute nitric acid, diluted with water, and prepared as the measurement sample. The Zr content in the measurement sample was measured using ICP-OES (Agilent 5800), and this content was defined as the Zr content in the particles. The ZrO2 content was determined from the Zr content in the particles.

[0049] (4) Crystal structure (crystallite size, peak intensity ratio, main peak) The target powder (particle powder) was pulverized and prepared as a sample for measurement. The crystal structure was measured using a Rigaku MiniFlex® 600 X-ray diffraction analyzer. The crystal structure can be identified using the PDXL2 analysis software. The crystallite size can be calculated by measuring the half-width β around 2θ = 31.5° of the perovskite structure and using Scherrer's equation "D = Kλ / βcosθ" from the half-width β (rad). Here, D is the crystallite size (Å), K is the Scherrer constant, λ is the X-ray wavelength (1.7889 Å), and θ is the reflection angle. The particles can take on either a tetragonal or cubic crystal structure. If the crystal structure is tetragonal, the half-width β at Miller index "101" is measured, and if it is cubic, the half-width β at Miller index "110" is measured. Using the analysis software PDXL2 (version 2.0.3.0), peak search (hybrid search match) was performed, and the ratio [I i / I p The following was determined: In tetragonal crystals, the peak at Miller index "101" is the main peak, and in cubic crystals, the peak at Miller index "110" is the main peak.

[0050] (5) Average particle diameter (D50, D90) One g of particle dispersion was filled into a measurement cell. To ensure uniformity within the cell, the liquid was drawn up using a dropper and returned to the cell. This process was repeated twice to obtain the measurement sample. The particle size distribution of the dispersion was measured using dynamic light scattering with a particle size distribution analyzer (NanoTrac® UPA-UT151, manufactured by Nikkiso Co., Ltd.). D50 and D90 were determined from the particle size distribution. In addition, the average particle diameter [D50] / crystallite diameter was calculated.

[0051] (6) Weight change rate (C 200 -C 1000 ) / C 200 An alcohol dispersion was sampled into an evaporating dish so that the weight after drying was 1.5 g, and dried at 200°C for 1 hour to obtain a dried product. After measuring the weight of the dried product, it was transferred to a crucible and fired at 1000°C for 1 hour to obtain a fired product. The weight after firing was measured. The weight of the dried product was C 200 The weight of the fired product is C 1000 And the rate of change in weight (C 200 -C 1000 ) / C 200 The result was calculated.

[0052] The obtained particles were evaluated by the following methods (I) to (III). The evaluation results for other examples and comparative examples are shown in Table 3.

[0053] (evaluation) (I) SY Test (Evaluation of photocatalytic activity (measurement of fading rate)) The particle alcohol dispersion was diluted with denatured alcohol to a particle concentration of 0.5% by weight. Next, a glycerin solution of sunset yellow FCF dye with a solid content concentration of 0.02% by mass was added to this organic solvent dispersion to prepare the measurement sample. At this time, the alcohol dispersion and glycerin solution were mixed so that the mass ratio (mass of organic solvent dispersion / mass of glycerin solution) was 1 / 3. This measurement sample was placed in a quartz cell with a depth of 1 mm, a width of 1 cm, and a height of 5 cm. The absorbance of this measurement sample before UV irradiation at a wavelength of 490 nm (A0) and the absorbance after n hours of UV irradiation (A0) were measured. nThe colorfastness of the dye was measured using a UV-Vis spectrophotometer (JASCO, V-550), and the fading rate of the dye at 180 minutes of UV irradiation (SY fading rate) was calculated from Equation 1 below. A lower SY fading rate indicates lower photocatalytic activity.

[0054] Fading rate=(A n -A0) / A0×100(%)...(Formula 1)

[0055] The ultraviolet irradiation conditions are as follows: An intensity of 0.4 mW / cm² is applied to a 1 cm wide x 5 cm high surface of a quartz cell. 2 A UV lamp (LUV-6, manufactured by AS ONE) with a selected wavelength range of I-line (wavelength 365nm) is placed at a position corresponding to a wavelength of 365nm. This UV lamp is used to irradiate the sample placed in the quartz cell with ultraviolet light.

[0056] (II) Particle refractive index Np' The particle refractive index Np' was determined using the following method. The refractive index Np' was similarly determined in the following examples and comparative examples.

[0057] The coating solution obtained by the method described below was applied to a silicon wafer (Matsuzaki Seisakusho Co., Ltd.: 6-inch dummy wafer (P-type), thickness: 625 μm) by spin coating. This coating solution was dried at 80°C for 2 minutes. An eye UV meter was used to measure 3000 mJ / cm². 2 Film-coated substrates (silicon wafers) were fabricated by irradiating a dried coating solution with ultraviolet light under the specified conditions. The refractive index Nav' of these film-coated substrates (silicon wafers) was measured using a spectroscopic ellipsometry (SE-2000, manufactured by Nippon Semilab Co., Ltd.).

[0058] The particle refractive index Np' was calculated from the following equation 2.

[0059] Particle refractive index Np' = (film refractive index - resin refractive index × volume fraction of resin) / volume fraction of particles ... (Equation 2)

[0060] The volume fraction of the resin was calculated using the following formula 3.

[0061] Volume fraction of resin = Volume of resin / (Volume of resin + Volume of particles) = (Weight of resin [g] / Density of resin [g / cm³]) 3 ]) / (Weight of resin [g] / Density of resin [g / cm³] 3 ] + Particle weight [g] / Specific gravity dp [g / cm³] 3 ])...(Formula 3)

[0062] The volume fraction of the particles was calculated using the following equation 4.

[0063] Particle volume fraction = Particle volume / (Resin volume + Particle volume) =(particle weight [g] / specific gravity dp [g / cm³]) 3 ]) / (Weight of resin [g] / Density of resin [g / cm³] 3 ] + Particle weight [g] / Specific gravity dp [g / cm³] 3 ])...(Formula 4)

[0064] Here, the weight of the resin is the weight of the resin in the coating solution prepared in (Preparation of Coating Solution) described later (in this case, 0.5 g of light acrylate DPE-6A was used), the specific gravity of the resin is assumed to be 1.2 g / ml for light acrylate DPE-6A, and the refractive index of the resin is assumed to be 1.515 for light acrylate DPE-6A. Also, dp is the specific gravity of the particles. The specific gravity dp is the sum of the product of the content [weight %] of each component contained in the particles (it was assumed that the components in the particles consist of two types: barium titanate [BaTiO3] and barium zirconate [BaZrO3]) and the specific gravity, and was calculated from the following equation 5.

[0065] Specific gravity dp = barium titanate content × specific gravity of barium titanate + Barium zirconate content × Specific gravity of barium zirconate ... (Equation 5)

[0066] The barium titanate and barium zirconate content were calculated using the following equations 6 and 7. The specific gravity of barium titanate was assumed to be 5.52 g, and the specific gravity dp of barium zirconate was assumed to be 4.97 g / ml.

[0067] Barium titanate content = Q / (Q+R)···(Equation 6) Barium zirconate content = R / (Q+R)···(Equation 7)

[0068] Here, Q and R were calculated from equations 8 and 9 below.

[0069] Q = TiO2 content [weight %] × Molecular weight of barium titanate (233.19 g / mol) / Molecular weight of titanium dioxide (79.88 g / mol) ... (Equation 8) R = ZrO2 content [weight %] × Molecular weight of barium zirconate (276.55 g / mol) / Molecular weight of zirconium oxide (123.22 g / mol) ... (Equation 9)

[0070] Here, the TiO2 content and ZrO2 content are the values ​​calculated in (3) Particle Composition described above.

[0071] (III) Average particle size after PGM substitution (D50, D90) 63 g of the particle alcohol dispersion and 27 g of PGM were mixed and concentrated in an evaporator at 40°C until the solid content concentration reached 25% by weight or more, to obtain the PGM-substituted dispersion. The average particle size of the PGM-substituted dispersion (D50, D90) was measured using the same method as for the average particle size described above (however, the PGM-substituted dispersion was used instead of the particle dispersion).

[0072] (Preparation of the coated film) The alcohol dispersion was concentrated to a solid content of 18% using an evaporator, and then portioned out to a solid content of 0.75 g. This was mixed with 0.5 g of a polyfunctional acrylate monomer (Light Acrylate DPE-6A, manufactured by Kyoeisha Chemical Co., Ltd.) as a binder and 0.03 g of a photopolymerization initiator (Omnirad® TPO H, manufactured by IGM RESINS BV). PGME was added to this mixture to a total volume of 5 g to prepare the coating solution. The specific gravity and refractive index of the binder (DPE-6A) were 1.2 g / ml and 1.515, respectively.

[0073] (Membrane evaluation) The obtained particles were evaluated by the following methods (IV) to (V). The evaluation results for other examples and comparative examples are shown in Table 3.

[0074] (IV) Film refractive index The Nav' measured in the above section (II) Particle refractive index Np' was defined as the film refractive index.

[0075] (V) Membrane haze The glass substrate was spin-coated and measured using a haze meter (NDH5000, manufactured by Nippon Denshoku Kogyo Co., Ltd.).

[0076] [Example 2] This example is the same as Example 1, except for the following differences. Specifically, in the third step, 16.0 g of tetraisopropoxytitanium (Orgatics TA-8; Ti concentration 16.85 wt%) was added to 100 g of the supernatant from the second step in a glove box under a nitrogen gas atmosphere and mixed. Subsequently, 24.9 g of zirconium tetran-n-butoxide (Orgatics ZA-65; Zr concentration 20.7 wt%) was added and mixed to obtain a mixture.

[0077] [Example 3] This embodiment is the same as in Embodiment 2, except for the following differences: in the third step, the amount of Orgatics TA-8 added was 22.4 g, and the amount of Orgatics ZA-65 added was 14.9 g.

[0078] [Example 4] This example is the same as Example 2, except for the following difference: 31.8 g of Orgatic TA-30 was added instead of Orgatic TA-8.

[0079] [Example 5] This embodiment is the same as in Embodiment 2, except for the following difference: In the third step, the amount of Orgatics TA-8 added was 28.9 g, and the amount of Orgatics ZA-65 added was 5 g.

[0080] [Comparative Example 1] 523 g of a 7.66% by mass aqueous solution of titanium tetrachloride (in TiO2 equivalent) and 523 g of a 7.66% by mass aqueous ammonia were mixed to prepare a white slurry (gel) with a pH of 9.2. This slurry was filtered, and the gel was washed with pure water to obtain 400.5 g of cake with a solid content of 10% by mass. The cake was diluted to 1.5% by mass with pure water to obtain another slurry. 457.7 g of 35% by mass aqueous hydrogen peroxide was added to this slurry. This dispersion was heated at 80°C for 1 hour. 877 g of pure water was added to this dispersion to obtain a dispersion of a titanium-containing compound (titanium oxide concentration of 1.0% by weight in TiO2 equivalent). A cation exchange resin (manufactured by Mitsubishi Chemical Corporation) was added to 4005 g of the titanium-containing compound dispersion. 495 g of a potassium stannate aqueous solution diluted to 1% by weight with pure water was added to this dispersion. The ion exchange resin was separated from this dispersion. This dispersion was hydrothermally synthesized in an autoclave at 165°C for 18 hours to obtain 4500 g of a core particle dispersion. This aqueous dispersion was diluted to a solid content concentration of 1% by mass. Silica sol (manufactured by JGC Catalysts & Chemicals Co., Ltd.: Cataloid® SN-350, with a specific surface area of ​​silica of 375 m²) was added to 9000 g of this aqueous dispersion. 236 g of silica (containing 15% by weight) was added. This dispersion was hydrothermally synthesized at 165°C for 18 hours using an autoclave. This dispersion was cooled to room temperature. By concentrating this dispersion using an ultrafiltration membrane apparatus, 2385 g of an aqueous dispersion of particles (solid content concentration of 4% by mass) was obtained. In other words, the particles were surface-treated with silica. To 2250 g of this aqueous dispersion of particles, 2250 g of methanol and 19.9 g of orthopropyl ethyl acid were added. By heating and stirring this dispersion at 50°C for 18 hours, an aqueous / methanol dispersion of particles was obtained. After cooling the dispersion to room temperature, the solvent of the dispersion was replaced with methanol using an ultrafiltration membrane. By concentrating this dispersion, 531 g of an alcohol dispersion of particles (solid content concentration of 20% by mass) was obtained. The water content in this dispersion was 0.3% by mass. 10.1 g of 5% by mass aqueous ammonia was added to this alcohol dispersion. Furthermore, 30.1 g of KBM-503 was added to this alcohol dispersion as a second surface treatment agent. This dispersion was heated and stirred at 50°C for 18 hours. This dispersion was cooled to room temperature. Using a rotary evaporator, the solvent in this dispersion was replaced with PGM, which is more hydrophobic than alcohol. This yielded 570 g of a PGM dispersion of particles (solid content concentration 20% by mass).

[0081] [Comparative Example 2] Under a nitrogen atmosphere, 163.78 g of zirconium isopropoxide and 300 g of isopropyl alcohol were added and stirred for 30 minutes to dissolve. Then, 70 g of deionized water was added over 60 minutes to obtain a zirconium hydroxide slurry. The obtained zirconium hydroxide was filtered, washed with water, and water was added to a concentration of 1.5 mol / L in terms of ZrO2. Then, it was placed in an autoclave and hydrothermally treated at 150°C for 5 hours. 175.8 g of barium hydroxide octahydrate was added to 320 g of the slurry obtained from the hydrothermal treatment, and water was added to adjust the slurry concentration to 1 mol / L (in terms of BaZrO3). This was placed in an autoclave and hydrothermally treated at 150°C for 5 hours.

[0082] [Comparative Example 3] This comparative example differs from Example 1 in the following respects. Specifically, in the third step of Example 1, 32.1 g of tetraisopropoxytitanium (Orgatics® TA-8, manufactured by Matsumoto Fine Chemical Co., Ltd.; Ti concentration 16.85% by weight) was added instead of ZA-65.

[0083] [Table 1]

[0084] [Table 2]

[0085] [Table 3]

Claims

1. A dispersion comprising perovskite particles and an organic solvent, The atomic ratio (Zr / M) of zirconium (Zr) to alkaline earth metal (M) obtained by measuring the aforementioned particles by X-ray photoelectron spectroscopy is 0.05 or higher. In the spectrum obtained by measuring the aforementioned particles using infrared spectroscopy, 2830 cm⁻¹ -1 Strength I ２８３０ And, 3500cm -1 Strength I ３５００ Ratio to (I ２８３０ / I ３５００ A dispersion in which the ratio is 0.11 to 0.

3.

2. The dispersion according to claim 1, characterized in that the particles contain 40 to 70% by weight of alkaline earth metal (M) in terms of MO.

3. The aforementioned particles contain titanium TiO ２ It contains more than 5% by weight, The dispersion according to claim 1, wherein the atomic ratio (Ti / M) of titanium (Ti) to alkaline earth metal (M) obtained by measuring the particles by X-ray photoelectron spectroscopy is 0.6 or less.

4. The atomic ratio (Zr / M) of zirconium (Zr) and alkaline earth metal (M) obtained by measurement by X-ray photoelectron spectroscopy is 0.05 or more, and in the spectrum obtained by measurement by infrared spectroscopy, 2830 cm -1 the intensity I ２８３０ and, 3500 cm -1 the intensity I ３５００ and the ratio (I ２８３０ / I ３５００ ) is 0.11 to 0.3 of perovskite-structured particles.

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