Composite particles, method for producing composite particles, fluororesin-containing particles, method for producing fluororesin-containing particles, and nanoparticle complex-containing sheet

Abstract

The purpose of the present invention is to provide composite particles having nanoparticles that are excellent in terms of weather resistance. Composite particles according to an embodiment of the present invention each include at least one nanoparticle complex and an aggregate of a plurality of functional particles. The nanoparticle complex is present inside an aggregate structure that is formed of the aggregate of the functional particles, and the nanoparticle complex is held inside the aggregate structure by intermolecular force between the nanoparticle complex and the functional particles.

Description

Composite particles, method for producing composite particles, fluororesin-containing particles, method for producing fluororesin-containing particles, and nanoparticle composite-containing sheet

[0001] The present invention relates to composite particles, a method for producing composite particles, fluororesin-containing particles, a method for producing fluororesin-containing particles, and a nanoparticle composite-containing sheet. This application claims priority to U.S. Provisional Application No. 63 / 554,647 filed February 16, 2024, U.S. Provisional Application No. 63 / 555,716 filed February 20, 2024, and U.S. Provisional Application No. 63 / 555,725 filed February 20, 2024, the contents of all of which are incorporated herein by reference.

[0002] In general, nanoparticles have a large specific surface area, which means that their surface is prone to oxidation and aggregation depending on their composition. Furthermore, quantum dots (QDs), in particular, have a highly reactive surface, which easily reacts with moisture and oxygen in the atmosphere and causes degradation. To address these issues, much research has been conducted into protecting the surface of quantum dots.

[0003] For example, Patent Document 1 discloses a method for producing a quantum dot material, the method comprising: mixing a core-forming metal complex with a pnictogen compound to form a nanocrystalline core material, adding a modifier containing chlorine and / or bromine to a solution containing the nanocrystalline core material, modifying the surface of the nanocrystalline core material with the modifier, mixing an outer shell-forming metal complex and a chalcogen compound with a solution containing the modified nanocrystalline core material to form an outer shell on each of the modified nanocrystalline core materials, and modifying the surface of the outer shell with the modifier added to the solution containing the nanocrystalline core material. Patent Document 2 discloses quantum dots with improved stability, the surfaces of which are modified with bidentate or higher-coordinated ligands having two or more functional groups that interact with the semiconductor crystalline particles.

[0004] Quantum dots processed in this way are expected to be used as wavelength conversion materials for displays, biomarkers for medical use, and solar cell materials.

[0005] International Publication No. 2017 / 188300 Japanese Patent Application Laid-Open No. 2019-099694

[0006] Murray et.al J. Am. Chem. Soc. 1993, 115, 8706-8715

[0007] As mentioned above, many studies have been conducted on methods for protecting the surfaces of nanoparticles by treating the surfaces of the nanoparticles with a substance different from the nanoparticles themselves to form nanoparticle composites.

[0008] However, in the surface treatment of nanoparticles with ligands as described in Patent Document 2, the ligands have poor heat resistance, so when the nanoparticle conjugate is heated, the ligands are easily desorbed from the nanoparticle surface due to thermal vibration. When the ligands are desorbed from the nanoparticle conjugate, the sites on the nanoparticle surface where the ligands were desorbed become attack points for moisture and oxygen, which can cause a deterioration in the properties of the nanoparticles.

[0009] An object of the present invention is to provide composite particles having nanoparticles that are excellent in weather resistance.

[0010] A composite particle according to an embodiment of the present invention is a composite particle comprising at least one nanoparticle composite and an aggregate of a plurality of functional particles, wherein the nanoparticle composite is present inside an aggregate structure formed by the aggregate of the functional particles, and the nanoparticle composite is held inside the aggregate structure by intermolecular forces between the nanoparticle composite and the functional particle.

[0011] According to the present invention, composite particles having nanoparticles with excellent weather resistance can be provided.

[0012] FIG. 1A is a diagram showing an outline of an example of the morphology of a composite particle according to an embodiment of the present invention. FIG. 1B is a diagram showing an outline of an example of the morphology of a composite particle according to an embodiment of the present invention. FIG. 1C is a diagram showing an outline of an example of the morphology of a composite particle according to an embodiment of the present invention. FIG. 2A is a scanning electron microscope (SEM) image of a composite particle according to an embodiment of the present invention. FIG. 2B is a scanning electron microscope (SEM) image of a composite particle according to an embodiment of the present invention. FIG. 2C is a scanning electron microscope (SEM) image of a composite particle according to an embodiment of the present invention. FIG. 2D is a scanning electron microscope (SEM) image of a composite particle according to an embodiment of the present invention. FIG. 3 is a transmission electron microscope (TEM) image of a composite particle according to an embodiment of the present invention. FIG. 4A is a diagram showing an outline of an example of the morphology of a fluororesin-containing particle according to an embodiment of the present invention. FIG. 4B is a diagram showing an outline of an example of the morphology of a fluororesin-containing particle according to an embodiment of the present invention. FIG. 4C is a diagram showing an outline of an example of the morphology of a fluororesin-containing particle according to an embodiment of the present invention. FIG. 4D is a diagram showing an outline of an example of the morphology of a fluororesin-containing particle according to an embodiment of the present invention. FIG. 4E is a diagram showing an outline of an example of the morphology of a fluororesin-containing particle according to an embodiment of the present invention. Fig. 5A is a scanning electron microscope (SEM) image of a fluororesin-containing particle according to an embodiment of the present invention. Fig. 5B is a scanning electron microscope (SEM) image of a fluororesin-containing particle according to an embodiment of the present invention. Fig. 5C is a scanning electron microscope (SEM) image of a fluororesin-containing particle according to an embodiment of the present invention. Fig. 5D is a scanning electron microscope (SEM) image of a fluororesin-containing particle according to an embodiment of the present invention. Fig. 5E is a scanning electron microscope (SEM) image of a fluororesin-containing particle according to an embodiment of the present invention.

[0013] A composite particle according to an embodiment of the present invention includes at least one nanoparticle composite and an aggregate of multiple functional particles. The nanoparticle composite is surrounded by the multiple functional particles. That is, the nanoparticle composite is present within an aggregate structure formed by the aggregate of functional particles, and the nanoparticle composite is held within the aggregate structure by intermolecular forces between the nanoparticle composite and the functional particle. In one example, the nanoparticle composite is composed of a nanoparticle and a ligand coordinated to its surface.

[0014] FIGS. 1A to 1C show examples of composite particles according to embodiments of the present invention. Composite particles 100, 110, and 120 are composed of a nanoparticle composite 11 and functional particles 12. As shown in FIGS. 1A to 1C, composite particles 100, 110, and 120 have a structure in which a nanoparticle composite 11 is surrounded by multiple functional particles 12. The nanoparticle composite 11 is encapsulated in an aggregate structure composed of an aggregate of multiple functional particles 12. The nanoparticle composite 11 is held in the internal space of the aggregate structure by intermolecular forces (repulsive forces) acting between the ligands of the nanoparticle composite 11 and the functional particles 12. As shown in FIG. 1B, the aggregate structure composed of an aggregate of multiple functional particles 12 does not necessarily contain a single nanoparticle composite 11; multiple nanoparticle composites 11 may be included. Note that the structures of the composite particles shown in FIGS. 1A to 1C are merely examples, and do not necessarily limit the structure of composite particles according to embodiments of the present invention to the structures shown in FIGS. 1A to 1C.

[0015] Preferred embodiments of the composite particle will be described in detail below, with each component being described in detail. <Nanoparticles> The nanoparticle composite constituting the composite particle according to the embodiment of the present invention includes nanoparticles and a ligand. Examples of nanoparticles constituting the nanoparticle composite include metal nanoparticles and semiconductor nanoparticles (quantum dots). There are no particular limitations on the metal nanoparticles, and examples include particles with a particle size of 1 nm to 100 nm made of metals such as Ni and Ag or alloys. Among nanoparticles, quantum dots are particularly susceptible to degradation due to external factors. Therefore, when the nanoparticles are quantum dots, the effect of making it difficult for the ligand to be released is more pronounced when the nanoparticle composite is encapsulated in an aggregate structure made up of an aggregate of functional particles.

[0016] In the present invention, quantum dots refer to nanoscale semiconductor crystal nanoparticles of 1 nm to 100 nm that have unique optical properties according to quantum mechanics. Quantum dots include those having the properties described in Non-Patent Document 1, as well as those made of II-VI group elements, III-V group elements, IV group elements, or IV-VI group elements, but are not limited to these. The particle size of the nanoparticles can be measured, for example, by calculating the particle size of 10 or more particles in a particle image observed with a transmission electron microscope (TEM) as the equivalent circle diameter (Heywood diameter).

[0017] <Ligand> The ligand contained in the nanoparticle complex has a nanoparticle-binding group. The nanoparticle-binding group may be arranged at the end of the main chain or the end of the side chain of the ligand. The ligand may be linear or branched. In the present invention, the nanoparticle-binding group is a functional group capable of binding to a nanoparticle. The type of bond may be either a chemical bond or a physical bond. Specific examples include coordinate bonds, covalent bonds, hydrogen bonds, hydrophobic interactions, and physical adsorption. The nanoparticle-binding group is preferably a functional group that forms a strong bond with the nanoparticle surface. Examples of the nanoparticle-binding group include a thiol group (-SH), an amino group (-NH ２ ), carboxyl group (—COOH), phosphate group, sulfone group, imine group, imide group, amide group, cyanate group, etc. Depending on the surface composition of the nanoparticles, thiol group (—SH) or amino group (—NH ２ ) is preferred because it can strongly bond to the nanoparticle surface.

[0018] The ligand preferably has a small molecular weight. A small molecular weight of the ligand reduces the physical distance between the nanoparticle and the functional particle, thereby making it possible to further reduce the volume of the composite particle. Specifically, the molecular weight of the ligand is preferably 250 or less. By keeping the volume of the composite particle small, it is possible to increase the content of the composite particle in a dispersion containing the composite particle, a nanoparticle composite-containing sheet, etc., as described below.

[0019] From the above, particularly preferred forms of ligands include those containing a thiol group in the nanoparticle binding group and having a small molecular weight. Specific examples include mercaptopropionic acid, thiolactic acid, thioglycolic acid, etc. The use of mercaptopropionic acid, thiolactic acid, thioglycolic acid, etc. can suppress the detachment of the ligand from the nanoparticle surface, and can also increase the content of composite particles in the dispersion containing the composite particles described below, the nanoparticle composite-containing sheet, etc.

[0020] <Functional Particles> The functional particles form an aggregate structure surrounding the nanoparticle composite. More specifically, a plurality of functional particles are arranged around one or more nanoparticle composites to form an aggregate structure that holds the nanoparticle composites inside.

[0021] The particle size of the functional particles is preferably 1 nm to 100 nm. By having the particle size of the functional particles be 1 nm to 100 nm, the nanoparticle composite can be effectively surrounded. The particle size of the functional particles is determined by measuring the BET specific surface area and converting the value using a spherical model to an average particle size (BET diameter).

[0022] The number of functional particles that form one aggregate structure that holds a nanoparticle composite inside depends on the particle sizes of the nanoparticle composite and the functional particles, but is preferably 4 to 800 per nanoparticle composite, more preferably 4 to 600, and even more preferably 4 to 500. When the aggregate structure made up of functional particles has 4 to 800 particles per nanoparticle, the nanoparticle can be effectively encapsulated therein.

[0023] The functional particles may be inorganic or organic. By selecting appropriate functional particles, various properties can be imparted to the nanoparticle composite. Only one type of material may be selected as the functional particles, or multiple types may be combined. For example, titania fine particles (TiO ２ ), zinc oxide particles (ZnO), zirconia (ZrO ２ ) etc.

[0024] The composite particles according to the embodiment of the present invention contain functional particles and have the above-described structure, and therefore have improved initial fluorescence quantum efficiency compared to particles obtained without containing functional particles.

[0025] Furthermore, by selecting an appropriate substance as the functional particle, weather resistance can be imparted to the nanoparticle composite. It is preferable to select a substance as the functional particle that exerts a repulsive force on the ligand on the nanoparticle surface. The repulsive force between the ligand coordinated to the nanoparticle surface and the functional particle can prevent the ligand from detaching from the nanoparticle surface, which is thought to improve the weather resistance of the nanoparticle composite. For example, it is preferable that the functional particle exhibits a negative surface potential at 25°C and a pH of 2 or higher. This allows a repulsive force to act between the ligand of the nanoparticle composite and the functional particle, preventing the ligand from detaching from the nanoparticle.

[0026] As the functional particles that exert a repulsive force with the ligands on the nanoparticle surface, it is preferable to select, for example, silica particles. ２ The present inventors have found that when the functional particles are silica particles or particles containing Si, the weather resistance of the nanoparticle composite is improved. That is, the composite particles according to the embodiment of the present invention can improve weather resistance by including silica particles or particles containing Si as functional particles and having the above-described structure. In the present invention, "improved weather resistance" means that the fluorescence quantum efficiency after 100 hours of the heat and humidity resistance test described below does not decrease by 20% or more from the initial fluorescence quantum efficiency, preferably by 15% or less, and more preferably by 10% or less.

[0027] As described above, the repulsive force generated between the functional particles and the ligand makes it difficult for the ligand to detach from the surface of the nanoparticle, thereby improving the weather resistance of the nanoparticle composite. Therefore, when particles other than silica particles or particles containing Si are selected as the functional particles, it is preferable to modify the surface of the functional particles so that a repulsive force is generated between the functional particles and the ligand.

[0028] To improve the initial fluorescence quantum efficiency of composite particles, particles other than silica particles may be mixed as functional particles. For example, the aforementioned silica particles and titania particles may be mixed in a ratio appropriate for the purpose and application to form an aggregate structure, and the nanoparticle composite may be encapsulated in the aggregate structure. In this case, the ratio of silica particles to functional particles other than silica particles is 10 vol. % or more, preferably 30 vol. % or more, more preferably 50 vol. % or more, and even more preferably 70 vol. % or more, by volume, relative to the total functional particles, thereby improving the initial fluorescence quantum efficiency of the composite particles.

[0029] <Composite Particles> Composite particles according to embodiments of the present invention have a structure in which a nanoparticle composite is encapsulated in an aggregate structure composed of an aggregate of multiple functional particles. The nanoparticles described in Patent Document 1 are only surface-modified with a modifier, without any treatment to improve dispersibility. Therefore, in their original state, the nanoparticles are prone to aggregation, which may result in a deterioration in luminescence properties. In contrast, the composite particles according to embodiments of the present invention have ligands coordinated to the nanoparticle surface, which can prevent aggregation of the nanoparticles even when redispersed in a dispersion medium, thereby suppressing a deterioration in luminescence properties due to nanoparticle aggregation. Furthermore, by having the above-described configuration, the composite particles according to embodiments of the present invention can increase the spacing between the nanoparticles due to physical contact between the functional particles, thereby preventing aggregation.

[0030] The composite particles according to the embodiments of the present invention have a configuration in which a nanoparticle composite is encapsulated in an aggregate structure composed of a plurality of functional particles, and therefore have a particle size on the order of microns in the composite particle state, making them easy to handle. Furthermore, when the composite particles according to the embodiments of the present invention are added to any dispersion medium, at least a portion of the composite particles can be redispersed in the dispersion medium in the form of nanoparticle composites and / or functional particles. Thus, by adopting the configuration of the composite particles according to the embodiments of the present invention, the nanoparticle composite can maintain a high fluorescence quantum efficiency both in the form of composite particles and in the form dispersed in a dispersion medium, thereby widening the window of application of the nanoparticle composite.

[0031] As the nanoparticle composite contained in the composite particle, for example, the nanoparticles are preferably quantum dots containing Zn on their surfaces, and the ligands preferably have thiol groups as nanoparticle binding groups capable of forming Zn-S bonds on the nanoparticle surfaces. In this case, the functional particles preferably include silica particles. Examples of quantum dots containing Zn on the surface include, but are not limited to, CdS / ZnSe having a core-shell structure in which the core is CdS and the shell is ZnSe, CdSe / ZnSe having a core-shell structure in which the core is CdSe and the shell is ZnSe, CdS / ZnSe / ZnS having a core-shell structure in which the core is CdS, the first shell is ZnSe, and the second shell is ZnS, CdSe / ZnSe / ZnS having a core-shell structure in which the core is CdSe, the first shell is ZnSe, and the second shell is ZnS, InP / ZnSe having a core-shell structure in which the core is InP and the shell is ZnSe, and InP / ZnSe / ZnS having a core-shell structure in which the core is InP, the first shell is ZnSe, and the second shell is ZnS.

[0032] When the composite particles have the above structure, the nanoparticles and the ligand form a Zn—S bond on the nanoparticle surface, which further suppresses the detachment of the ligand, thereby improving the weather resistance of the composite particles in addition to the effect achieved when silica particles are used as functional particles.

[0033] <Fluororesin-containing particles> The fluororesin-containing particles according to the embodiment of the present invention are composed of at least one nanoparticle composite, a plurality of functional particles, and a fluororesin. In the fluororesin-containing particles, the functional particles form an aggregate structure encapsulating the nanoparticle composites. In the fluororesin-containing particles, the fluororesin may be such that at least a portion of the periphery of the interior or exterior of the aggregate structure formed by an aggregate of a plurality of functional particles is covered with the fluororesin.

[0034] 4A to 4E show examples of fluororesin-containing particles according to an embodiment of the present invention. In the fluororesin-containing particle 200 shown in FIG. 4A, the surface of a nanoparticle composite 21 is covered with a fluororesin 22. In the fluororesin-containing particle 210 shown in FIG. 4B, functional particles 23 are positioned around the nanoparticle composite 21, and the voids between the nanoparticle composites 21 are filled with a fluororesin 22, forming a particulate shape. In the fluororesin-containing particle 220 shown in FIG. 4C, a nanoparticle composite 21 is disposed inside an aggregate structure formed by an aggregate of a plurality of functional particles 23, and the internal voids and the external periphery of the aggregate structure are filled with a fluororesin 22, forming a particulate shape. In the fluororesin-containing particle 230 shown in FIG. 4D, two nanoparticle composites 21 are disposed inside an aggregate structure formed by an aggregate of a plurality of functional particles 23, and the internal voids and the external periphery of the aggregate structure are filled with a fluororesin 22, forming a particulate shape. The fluororesin-containing particle 240 shown in Figure 4E is a series of aggregate structures made up of an aggregate of multiple functional particles 23, with a nanoparticle composite 21 disposed inside each aggregate structure, and the internal voids and external periphery of the aggregate structure filled with fluororesin 22 to form a particle.

[0035] Note that the structures of the fluororesin-containing particles shown in Figures 4A to 4E are merely examples, and do not mean that the structures of the fluororesin-containing particles according to embodiments of the present invention are limited to the structures shown in Figures 4A to 4E. For example, the fluororesin-containing particles 220, 230, and 240 shown in Figures 4C to 4E have nanoparticle composites 21 disposed within an aggregate structure formed by the aggregation of multiple functional particles 23, and the voids within the aggregate structure are filled with fluororesin 22 to form a particle. However, the voids within the aggregate structure do not necessarily have to be filled with fluororesin. Furthermore, while the fluororesin-containing particles 220, 230, and 240 shown in Figures 4C to 4E have the outer periphery of the aggregate structure completely covered with fluororesin 22, it is sufficient that the fluororesin covers at least a portion of the outer periphery of the aggregate structure.

[0036] Fluororesin-containing particles have a particle size on the order of microns, making them easy to handle. Furthermore, fluororesin has a high barrier property against water and a low absorptivity for light in the 200 nm to 800 nm wavelength range, reducing the energy loss to the nanoparticle composite. In the fluororesin-containing particles according to the present invention, the nanoparticles, ligands, and functional particles may have the same configurations as those described above in the description of the composite particles according to the present invention.

[0037] <Evaluation of Weather Resistance> The fluorescence quantum efficiency of nanoparticle composites and composite particles can be measured using a fluorescence quantum efficiency measurement system (QE-2100, manufactured by Otsuka Electronics Co., Ltd.). First, the nanoparticle composites or composite particles are packed into a sample holder and then irradiated with excitation light to obtain an emission spectrum. Optical properties such as fluorescence quantum efficiency (QY), peak wavelength (λmax), and full width at half maximum (FWHM) can be calculated based on the re-excitation-corrected emission spectrum obtained by subtracting the re-excitation fluorescence emission spectrum corresponding to the fluorescence emitted by re-excitation from the obtained emission spectrum. Note that the excitation light used for the measurement is a single light of 450 nm. In the heat and humidity resistance test described below, weather resistance was evaluated using the fluorescence quantum efficiency (QY) value measured at room temperature (25°C).

[0038] The heat and moisture resistance test is performed by storing the nanoparticle composite in a thermo-hygrostat chamber at a temperature of 60°C and a relative humidity of 90% for 100 hours. The retention rate of the fluorescence quantum efficiency before and after the heat and moisture resistance test is calculated using the fluorescence quantum efficiency (QYa) before the heat and moisture resistance test and the fluorescence quantum efficiency (QYb) after the heat and moisture resistance test according to the following formula (1): Fluorescence quantum efficiency retention rate = {(QYa - QYb) / QYa} x 100 (1)

[0039] <Method for Producing Composite Particles> The method for producing composite particles according to an embodiment of the present invention is a method for producing composite particles comprising at least one nanoparticle composite and an aggregate of a plurality of functional particles. A nanoparticle composite dispersion in which the nanoparticle composite is dispersed in a dispersion medium is mixed with a functional particle dispersion in which functional particles are dispersed in a dispersion medium to prepare a mixed solution, and the mixed solution is dried to obtain composite particles. The nanoparticle composite can be obtained by bonding the nanoparticles and the ligand in a dispersion containing the nanoparticles and the ligand. After the nanoparticles and the ligand are bonded to obtain the nanoparticle composite, a specific ligand may be bonded to the nanoparticles using a known method (e.g., a ligand exchange method).

[0040] The nanoparticles, ligands, and functional particles used in the method for producing composite particles according to an embodiment of the present invention can be the same as those described above in the description of the composite particles according to an embodiment of the present invention.

[0041] The dispersion medium used for the nanoparticle composite dispersion is preferably an organic solvent. Similarly, the dispersion medium used for the functional particle dispersion is preferably an organic solvent. Note that a commercially available functional particle dispersion containing functional particles may be used.

[0042] The nanoparticle composite dispersion is preferably compatible with the functional particle dispersion. For example, when the dispersion medium used in the functional particle dispersion is an aqueous dispersion, the dispersion medium used in the nanoparticle composite dispersion is preferably also aqueous. Of course, when the dispersion medium used in the functional particle dispersion is an organic solvent, the dispersion medium used in the nanoparticle composite dispersion is preferably also an organic solvent.

[0043] In the present invention, a compatible system refers to a system in which the difference in SP value between the dispersion media used in the nanoparticle composite dispersion and the functional particle dispersion is 3.0 or less. The SP value here is the Hildebrand solubility parameter, which is a value calculated from the Hansen solubility parameter. The Hansen solubility parameter can be determined using values ​​in handbooks, such as "Hansen Solubility Parameters: A User's Handbook," 2nd Edition, C. M. Hansen (2007), or the HSPiP program (2nd Edition) provided by Hanson and Abbot et al.

[0044] In the mixed solution of the nanoparticle composite dispersion and the functional particle dispersion, the nanoparticle composite and the functional particles are preferably in a dispersed state. Note that in the mixed solution, at least a portion of the nanoparticle composite and / or the functional particles may be aggregated.

[0045] As described above, composite particles can be obtained by drying the mixed solution obtained by mixing the nanoparticle composite dispersion and the functional particle dispersion. The method for drying the mixed solution is not particularly limited, and heat drying, vacuum drying, freeze drying, etc. can be used. Among them, spray drying, which dries the mixed solution in a droplet state, is preferred because it makes the composite particles more spherical.

[0046] <Method for producing fluororesin-containing particles> In a method for producing fluororesin-containing particles according to an embodiment of the present invention, the nanoparticle composite, functional particles, and fluororesin are mixed in a dispersion medium to prepare a preparation liquid, and the preparation liquid is then dried. The drying method is not particularly limited, and heat drying, vacuum drying, and freeze drying are preferred. Spray drying, which dries the preparation liquid in a droplet state, is preferred because it makes it easier for the fluororesin-containing particles to become more spherical.

[0047] In preparing the above-mentioned preparation liquid, it is preferable to mix the nanoparticle composite in the form of a nanoparticle composite dispersion, and the functional particles in the form of a functional particle dispersion. Furthermore, it is also possible to mix the fluororesin in the form of a fluororesin dispersion. In this case, it is preferable that the nanoparticle composite dispersion, the functional particle dispersion, and the fluororesin dispersion are compatible with each other.

[0048] Furthermore, the fluororesin-containing particles can also be made using the composite particles according to the embodiment of the present invention as a raw material. In this case, the composite particles and the fluororesin are mixed in a dispersion medium to prepare a preparation liquid, and the preparation liquid is dried to obtain the fluororesin-containing particles. In this case, in preparing the preparation liquid, the composite particles can be made into a composite particle dispersion liquid, and the fluororesin can be mixed in the form of a fluororesin dispersion liquid.

[0049] <Dispersion> The composite particles and fluororesin-containing particles according to the embodiment of the present invention can be dispersed in any dispersion medium to form a dispersion containing a nanoparticle composite.

[0050] <Nanoparticle composite-containing sheet> The fluororesin-containing particles according to the embodiment of the present invention described above can be dispersed in any resin or matrix to form a nanoparticle composite-containing sheet containing the nanoparticle composite. Such a nanoparticle composite-containing sheet, in which the fluororesin-containing particles according to the embodiment of the present invention are formed into a sheet, has improved light resistance. The light resistance of the nanoparticle composite-containing sheet was measured in a test box adjusted to a temperature of 45°C by irradiating the nanoparticle composite-containing sheet with a single light of 440 nm at 408 mW / cm ２ The fluorescent quantum efficiency after a certain period of time is evaluated as a maintenance rate relative to the initial fluorescent quantum efficiency of the sheet.

[0051] The composite particle according to an embodiment of the present invention has the following configuration. (1) A composite particle comprising at least one nanoparticle composite and an aggregate of a plurality of functional particles, wherein the nanoparticle composite is present inside an aggregate structure formed by the aggregate of the functional particles, and the nanoparticle composite is held inside the aggregate structure by intermolecular forces between the nanoparticle composite and the functional particles. (2) The composite particle according to (1) above, wherein the functional particles comprise silica particles. (3) The composite particle according to (1) or (2) above, wherein the functional particles exhibit a negative surface potential at 25°C and in a pH range of 2 or higher. (4) The composite particle according to any one of (1) to (3) above, wherein the number of functional particles is 4 to 800 for the at least one nanoparticle composite. (5) The composite particle according to any one of (1) to (4) above, wherein the nanoparticle composite comprises a nanoparticle and a ligand, and the ligand has a thiol group as a coordinating group that coordinates with the nanoparticle. (6) The composite particles according to any one of (1) to (5), wherein when the composite particles are added to a dispersion medium, at least a portion of the nanoparticle composite and / or the functional particles can be redispersed in the dispersion medium.

[0052] The method for producing composite particles according to an embodiment of the present invention employs the following configuration. (7) A method for producing composite particles containing at least one nanoparticle composite and an aggregate of a plurality of functional particles, comprising: mixing a nanoparticle composite dispersion in which the nanoparticle composite is dispersed in a dispersion medium with a functional particle dispersion in which functional particles are dispersed in a dispersion medium to prepare a mixed solution; and drying the mixed solution. (8) The method for producing composite particles according to (7) above, wherein the mixed solution is dried in a state in which the mixed solution is in the form of droplets. (9) The method for producing composite particles according to (7) or (8) above, wherein the dispersion medium used for the nanoparticle composite dispersion and the dispersion medium used for the functional particle dispersion are both organic dispersion media. (10) The method for producing composite particles according to any one of (7) to (9) above, wherein the nanoparticle composite dispersion and the functional particle dispersion are compatible with each other. (11) The method for producing composite particles according to any one of (7) to (10) above, wherein the nanoparticle composite and the functional particles are dispersed in the mixed solution. (12) The method for producing composite particles according to any one of (7) to (10) above, wherein at least a portion of the nanoparticle composites and / or the functional particles are aggregated in the mixed solution.

[0053] The fluororesin-containing particles of the present invention have the following configuration. (13) A fluororesin-containing particle comprising at least one nanoparticle composite, a plurality of functional particles, and a fluororesin. (14) The fluororesin-containing particle according to (13) above, wherein the plurality of functional particles form an aggregate structure encapsulating the nanoparticle composite. (15) The fluororesin-containing particle according to (13) or (14) above, wherein the functional particles comprise silica particles.

[0054] The method for producing fluororesin-containing particles of the present invention employs the following configuration. (16) A method for producing fluororesin-containing particles containing at least one nanoparticle composite, a plurality of functional particles, and a fluororesin, comprising mixing the nanoparticle composite, the functional particles, and the fluororesin in a dispersion medium to prepare a preparation liquid, and drying the preparation liquid. (17) The method for producing fluororesin-containing particles according to (16) above, wherein the nanoparticle composite is mixed in the state of a nanoparticle composite dispersion, and the functional particles are mixed in the state of a functional particle dispersion, when preparing the preparation liquid. (18) The method for producing composite particles according to (17) above, wherein the fluororesin is mixed in the state of a fluororesin dispersion, when preparing the preparation liquid, and the nanoparticle composite dispersion, the functional particle dispersion, and the fluororesin dispersion are compatible with each other.

[0055] The nanoparticle composite-containing sheet of the present invention employs the following configuration: (19) A nanoparticle composite-containing sheet containing the fluororesin-containing particles according to any one of (13) to (15) above.

[0056] It will be understood that the structures and / or methods described herein are presented by way of example and that numerous variations are possible, and therefore, these specific examples or examples should not be construed in a limiting sense. A particular procedure or method described herein may represent one of numerous processing methods. Thus, various acts illustrated and / or described may be performed in the order illustrated and / or described, or may be omitted. Similarly, the order of the methods described may be changed.

[0057] The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various methods, systems, and structures, as well as other features, functions, acts, and / or properties disclosed herein, and all equivalents thereof.

[0058] EXAMPLES The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0059] [Production of Nanoparticles] CdSe-based nanoparticles and InP-based nanoparticles were obtained according to the following method.

[0060] <Production of CdSe-based nanoparticles (CdSe / ZnSe / ZnS)> - Core preparation (CdSe: green) - First, selenium (0.79 g, 10 mmol) and trioctylphosphine (10.9 ml) were stirred in an argon gas atmosphere at 150 ° C for about 1 hour to completely dissolve the selenium and prepare a Se precursor. Next, cadmium acetate dihydrate (1.97 g, 7.5 mmol) and trioctylphosphine oxide (9.65 g) were placed in a flask, and the flask was purged with an argon gas atmosphere to prepare a Cd precursor. The Cd precursor was heated to 300 ° C, and 9.9 ml of Se precursor (containing 9 mmol of selenium) was added dropwise at once and stirred for 5 minutes. After cooling to room temperature, the resulting reaction mixture was purified with butanol and methanol to remove unreacted Cd and Se precursors, trioctylphosphine, and excess trioctylphosphine oxide. The purified reaction mixture was diluted with 10 ml of toluene to obtain a CdSe nanocrystal (green) solution.

[0061] - Core Preparation (CdSe: Red) - First, selenium (0.79 g, 10 mmol) and trioctylphosphine (10.9 ml) were stirred in an argon gas atmosphere at 150 °C for approximately 1 hour to completely dissolve the selenium, preparing the Se precursor. Next, cadmium acetate dihydrate (2.18 g, 8.3 mmol) and trioctylphosphine oxide (10 g) were placed in a flask, and the flask was purged with an argon gas atmosphere to prepare the Cd precursor. The Cd precursor was heated to 300 °C, and 9.9 ml of Se precursor (containing 9 mmol of selenium) was added dropwise at once and stirred for 8 minutes. After cooling to room temperature, the resulting reaction mixture was purified using butanol and methanol to remove unreacted Cd and Se precursors, trioctylphosphine, and excess trioctylphosphine oxide. The purified reaction mixture was diluted with 10 ml of toluene to give a CdSe nanocrystal (red) solution.

[0062] - Shell Preparation (CdSe / ZnSe / ZnS) - First, sulfur (0.32 g, 10 mmol) and trioctylphosphine (10.9 ml) were stirred in an argon gas atmosphere at 150°C for approximately 1 hour to completely dissolve the sulfur and prepare the sulfur precursor. 8 g of trioctylamine, 0.1 g of oleic acid, and 0.2 mmol of zinc acetate were added to a flask, and the reaction temperature was adjusted to 300°C while stirring. 0.1 ml of the CdSe nanocrystal solution prepared above was added to the reaction mixture, followed by 0.1 ml of the Se precursor and a reaction for approximately 1 hour. Then, 0.1 ml of the S precursor was added and a reaction for 1 hour was allowed to proceed. After the reaction was completed, the temperature of the reaction mixture was lowered to room temperature as quickly as possible, and a non-reactive solvent, ethanol, was added and centrifuged. The supernatant solution, after removing the precipitate from the centrifugation, was discarded, and CdSe / ZnSe / ZnS (green and red) was formed.

[0063] <Production of InP-based nanoparticles (InP / ZnSe / ZnS)> - Core preparation (InP: green) - Indium acetate (0.3 mmol) was added to a mixture of oleic acid (0.9 mmol) and octadecene (10 ml), heated to approximately 120°C under vacuum (<20 Pa), and reacted for 1 hour. The mixture reacted in vacuum was then returned to 25°C under a nitrogen atmosphere, and tris(trimethylsilyl)phosphine (0.2 mmol) was added, followed by heating to approximately 300°C and reacting for 10 minutes. The reaction solution was cooled to 25°C, and octanoic acid chloride (0.45 mmol) was added. The mixture was heated at approximately 250°C for 30 minutes and then cooled to 25°C to obtain an InP nanocrystal (green) solution.

[0064] - Core preparation (InP: red) - Indium acetate (0.3 mmol) was added to a mixture of oleic acid (0.9 mmol) and octadecene (10 ml), heated to approximately 120°C under vacuum (<20 Pa), and reacted for 1 hour. The mixture reacted in vacuum was then returned to 25°C under a nitrogen atmosphere, and tris(trimethylsilyl)phosphine (0.25 mmol) was added, followed by heating to approximately 300°C and reacting for 15 minutes. The reaction solution was cooled to 25°C, and octanoic acid chloride (0.45 mmol) was added. The mixture was heated at approximately 250°C for 30 minutes and then cooled to 25°C to obtain an InP nanocrystal (red) solution.

[0065] - Shell Preparation (InP / ZnSe / ZnS) - First, sulfur (0.32 g, 10 mmol) and trioctylphosphine (10.9 ml) were stirred in an argon gas atmosphere at 150°C for approximately 1 hour to completely dissolve the sulfur and prepare an S precursor. 8 g of trioctylamine, 0.1 g of oleic acid, and 0.2 mmol of zinc acetate were added to a flask, and the reaction temperature was adjusted to 300°C while stirring. 0.1 ml of the InP nanocrystal solution prepared above was added to the reaction mixture, followed by 0.1 ml of Se precursor and a reaction for approximately 1 hour. Then, 0.1 ml of S precursor was added and a reaction for 1 hour was performed. After the reaction was completed, the temperature of the reaction mixture was lowered to room temperature as quickly as possible, and a non-reactive solvent, ethanol, was added and centrifuged. The supernatant solution, after removing the precipitate from the centrifugation, was discarded, and InP / ZnSe / ZnS (green and red) was formed.

[0066] [Production of Nanoparticle Composite] <Preparation of Ligands> The following ligands A to D were prepared as ligands to be coordinated to the surface of the nanoparticles. A: Mercaptopropionic acid (Tokyo Chemical Industry Co., Ltd.) B: PEG thiol (details below) C: Dodecanethiol (Fujifilm Wako Pure Chemical Industries, Ltd.) D: Oleic acid (Fujifilm Wako Co., Ltd.)

[0067] - Preparation of Ligand B - Ligand B was prepared by the following method. 210 g of methoxy PEG-OH (number average molecular weight 450) and 93 g of triethylamine were placed in a flask and dissolved in 420 ml of THF (tetrahydrofuran). The solution was cooled to 0°C, and 51 g of methanesulfonic acid chloride was slowly added dropwise under a nitrogen atmosphere, taking care not to allow the reaction heat to cause the temperature of the reaction solution to exceed 5°C. The reaction solution was then warmed to room temperature and stirred for 2 hours. This solution was extracted with a chloroform-water system, and the organic phase was recovered. The resulting solution was dried over magnesium sulfate, the magnesium sulfate was removed by filtration, and the filtrate was concentrated by evaporation to obtain an oily intermediate. This was transferred to another flask, and 400 ml of a 1.3 M aqueous thiourea solution was added under a nitrogen atmosphere. The solution was refluxed for 2 hours, after which 21 g of NaOH was added and the mixture was refluxed for an additional 1.5 hours. The reaction solution was cooled to room temperature and neutralized by adding 1 M aqueous HCl until the pH reached 7. The resulting solution was extracted with a chloroform-water system to obtain the target ligand (PEG-SH, number average molecular weight 450).

[0068] <Ligand Exchange> Ligands A to D were coordinated to the nanoparticles according to the following method. - Coordination of Ligand A - Nanoparticles were dispersed in toluene in a flask to a mass ratio of 20%. 4.0 g of Ligand A was then added, and the mixture was heated to 120°C and stirred for 9 hours to carry out ligand exchange. The solution was then cooled, hexane was added, and the mixture was centrifuged to separate the aggregates from the supernatant. The supernatant, which was mainly composed of toluene and hexane, was then removed. Acetone and hexane were then added, and the mixture was washed several times. After removing the acetone and hexane, water was added, and an appropriate amount of tetramethylammonium hydroxide / methanol solution was added and stirred to prepare a nanoparticle composite dispersion in which the nanoparticle composites were dispersed.

[0069] - Coordination of Ligand B, C, or D - Nanoparticles were dispersed in toluene in a flask to a mass ratio of 20%, and 4.0 g of Ligand B was added. The mixture was stirred at 80°C to 110°C for 60 minutes under a nitrogen atmosphere and then cooled to 25°C, yielding a reaction solution of a nanoparticle composite. Nanoparticle composites were produced by changing the ligand to be coordinated with the nanoparticles. Table 1 shows the composition of the nanoparticle composite.

[0070]

[0071] [Confirmation of Dispersibility in Polar Solvents] In the present invention, the degree of polarity of a solvent is determined by its SP value. In the present invention, a solvent with an SP value of less than 8.8 is defined as a nonpolar solvent, and a solvent with an SP value of 8.8 or greater is defined as a polar solvent. QD1 (nanoparticle composite) shown in Table 1 above was dispersed in pure water with an SP value of 23.4 at a mass ratio of 20% by weight of the nanoparticle composite. As a result, no precipitation was observed, confirming dispersion. Furthermore, QD2 to QD8 were dispersed in propylene glycol monomethyl ether (PGM) with an SP value of 10.4 at a mass ratio of 20% by weight of the nanoparticle composite. As a result, no precipitation was observed for QD2 to QD6, confirming dispersion in the polar solvent, but it was confirmed that QD7 and QD8 were in an aggregated state in part of the dispersion.

[0072] [Production of Composite Particles] <Preparation of Nanoparticle Composite Dispersion, Functional Particle Dispersion, and Mixed Solution> Functional particles listed in Table 2 and various dispersion media listed in Table 3 were prepared. Nanoparticle composite dispersions were prepared using the nanoparticle composites and dispersion media prepared above in the combinations shown in Tables 4-1 and 4-2. Similarly, functional particle dispersions were prepared using the functional particles and dispersion media prepared above in the combinations shown in Tables 4-1 and 4-2. The prepared nanoparticle composite dispersions and functional particle dispersions were mixed so that the functional particle / nanoparticle composite ratio was as shown in Tables 4-1 and 4-2, and the concentration was appropriately adjusted so that the proportion (percentage) of the inorganic component was 10 wt. % to obtain mixed solutions. In many mixed solutions, both the nanoparticle composites and functional particles were well dispersed due to the compatibility between the nanoparticle composite dispersion and the functional particle dispersion. However, aggregation of the nanoparticle composites and / or functional particles was observed in some mixed solutions. In this experimental example, the mixed solution was obtained with the formulations shown in Tables 4-1 and 4-2, but any additive component can be added to the mixed solution as needed.

[0073]

[0074]

[0075]

[0076]

[0077] <Drying of Mixed Solution> The mixed solution prepared as described above was granulated and dried using a mini spray dryer (B-290, manufactured by BUCHI) to obtain composite particles. When the dispersion medium was an organic solvent, an inert loop (B-295, manufactured by BUCHI) was added as an accessory for safety purposes to obtain composite particles. A two-fluid nozzle was used as the spray nozzle, and the mixed solution was supplied at a supply rate of 1.0 ml / min at a pressure of 0.5 MPa and a gas temperature of 100°C to obtain composite particles from the mixed solution. Air was used as the gas when the mixed solution was aqueous, and N was used when the mixed solution was organic solvent-based. ２ Gas was used.

[0078] <Optical Properties and Weather Resistance Test of Composite Particles> The obtained composite particles were subjected to measurement of the fluorescence quantum efficiency. The fluorescence quantum efficiency of the composite particles was measured using a fluorescence quantum efficiency measurement system (QE-2100, manufactured by Otsuka Electronics). The composite particles were packed in a sample holder, and then irradiated with excitation light (single light of 450 nm) to obtain an emission spectrum. The initial fluorescence quantum efficiency (QY) of the composite particles was calculated based on the emission spectrum after re-excitation correction, which was obtained by excluding the re-excitation fluorescence emission spectrum corresponding to the fluorescence emitted by re-excitation from the obtained emission spectrum. ０ ) was calculated. After measuring the fluorescence quantum efficiency, the weather resistance of the composite particles was evaluated. In an embodiment of the present invention, the maintenance rate of the fluorescence quantum efficiency before and after a heat resistance and humidity resistance test is used as an index of weather resistance. The heat resistance and humidity resistance test was performed by placing the composite particles in a thermo-hygrostat (PHP-2J manufactured by ESPEC Corp.) set at a temperature of 60°C and a relative humidity of 90% and holding them for 500 hours, and then removing the composite particles from the thermo-hygrostat 100 hours, 300 hours, and 500 hours after placing the composite particles in the thermo-hygrostat, and measuring the fluorescence quantum efficiency in the same manner as described above. The fluorescence quantum efficiency after 100 hours, 300 hours, and 500 hours relative to the initial fluorescence quantum efficiency was calculated as the maintenance rate of the fluorescence quantum efficiency, respectively.

[0079] <Results> Tables 5 to 7 show the influence of the presence or absence of functional particles on the initial fluorescence quantum efficiency of composite particles.

[0080]

[0081]

[0082]

[0083] By using composite particles containing functional particles, the initial fluorescence quantum efficiency of the composite particles was high. Table 8 shows the effects on the weather resistance of the composite particles of the ligands of the nanoparticle composite and the functional particles that form the composite particles. The maintenance rate of the fluorescence quantum efficiency after 100 hours of heat and humidity resistance testing relative to the initial fluorescence quantum efficiency was used as an indicator of weather resistance.

[0084]

[0085] The coordinating group of the ligand of the nanoparticle composite that forms the composite particle is preferably a thiol group.Furthermore, the functional particles that form the composite particle are preferably silica particles or particles whose surface potential has been adjusted to be negative.

[0086] In addition, when the coordinating group of the ligand of the nanoparticle composite is not a thiol group, the weather resistance of the composite particle may decrease by 20% or more after 100 hours compared to the initial fluorescence quantum efficiency of the composite particle. Furthermore, when the functional particles constituting the nanoparticle composite are particles other than silica, the weather resistance of the composite particle may decrease by 40% or more after 100 hours compared to the initial fluorescence quantum efficiency of the composite particle. On the other hand, even when the functional particles are particles other than silica, composite particles with high weather resistance can be obtained by modifying the surface of the functional particles and using particles whose surface potential has been adjusted to a negative value (see Sample 40).

[0087] Therefore, the coordinating group of the ligand of the nanoparticle composite that forms the composite particle is a thiol group, and the functional particle that forms the composite particle is a silica particle or a particle with a surface potential adjusted to a negative value, thereby making it possible to obtain a composite particle with high weather resistance.

[0088] Table 9 shows the dispersion media used in the nanoparticle composite dispersion and functional particle dispersion when obtaining the composite particles, the types of nanoparticles and functional particles, the initial fluorescence quantum efficiency of the obtained composite particles, and the fluorescence quantum efficiency maintenance rate of the composite particles after a weather resistance test. SEM images of the obtained composite particles are shown in Figures 2A to 2D, and a TEM image is shown in Figure 3.

[0089]

[0090] Depending on the state of the mixed solution, composite particles of different shapes can be obtained, such as not only spherical but also balloon-like or doughnut-like shapes. This depends on the dispersion state of the nanoparticle composite and functional particles in the mixed solution, the viscosity of the mixed solution, the evaporation rate of the dispersion medium, and the affinity between the dispersion medium and the functional particles.

[0091] When forming the composite particles, it is preferable that the nanoparticle composite dispersion and the functional particle dispersion are compatible, and when the compatibility is high, composite particles such as those observed in Figures 2A to 2C can be obtained. On the other hand, when the compatibility between the nanoparticle composite dispersion and the functional particle dispersion is low, particularly when the dispersibility of the functional particles in the mixed solution of the nanoparticle composite dispersion and the functional particle dispersion is low, it was confirmed that the resulting composite particles have difficulty maintaining their particle shape, as observed in Figure 2D, and have a relatively low initial fluorescence quantum efficiency.

[0092] [Preparation of fluororesin-containing particles] <Preparation of preparation liquid> A preparation liquid for preparing fluororesin-containing particles was prepared. The preparation liquid was obtained by mixing a fluororesin, a nanoparticle composite dispersion, and a functional particle dispersion into a main dispersion medium in the combinations shown in Table 10. The nanoparticle composite, dispersion medium, and functional particles contained in the preparation liquid were those shown in Tables 1, 2, and 3, respectively. The fluororesins used were as follows: R1: Lumiflon LF200 (AGC) R2: Lumiflon LF810 (AGC)

[0093]

[0094] As mentioned above, it is also possible to prepare a preparation liquid using composite particles. When composite particles are used, the preparation liquid is prepared by adding the composite particles and the fluororesin to the main dispersion medium and mixing them. In this case, the combination of composite particles and fluororesin used in the preparation liquid is that shown in Table 11.

[0095]

[0096] <Drying of the prepared solution> The prepared solution prepared above was dried using a mini spray dryer (B-290, manufactured by BUCHI) and an inert loop (B-295, manufactured by BUCHI) to obtain fluororesin-containing particles. ２The gas was adjusted to a linear gas velocity of 150 m / sec, a pressure of 0.5 MPa, and a temperature of 70 to 80°C, and the preparation liquid was supplied at a supply rate of 1.0 ml / min. The obtained fluororesin-containing particles were recovered using a cyclone, but because some of the fluororesin-containing particles remained inside the spray dryer, both the fluororesin-containing particles inside the cyclone and the spray dryer were recovered during recovery. SEM images of the obtained fluororesin-containing particles are shown in Figures 5A to 5E.

[0097] [Preparation of nanoparticle composite-containing sheet] In a yellow room, 74.6 parts by mass of tricyclodecane dimethanol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.: A-DCP) as a polyfunctional (meth)acrylate compound, 18.7 parts of pentaerythritol tetrakis(3-mercaptopropionate) (manufactured by SC Organic Chemicals: PEMP) as a polyfunctional thiol compound, 1.0 parts by mass of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (manufactured by BASF: IRGACURE TPO) as a photopolymerization initiator, 0.7 parts by mass of titanium oxide particles (manufactured by Chemours: Typure R-706), and 5.0 parts by mass of the fluororesin-containing particles obtained above were mixed to obtain a composition. This composition was stirred and degassed, and the composition was applied to a thickness of 100 μm on a 75 μm PET film using an applicator. The applied composition was irradiated with ultraviolet light and solidified to form a resin layer, and then a 75 μm PET film was attached to the resin layer and laminated to produce a nanoparticle composite-containing sheet containing fluororesin-containing particles. This nanoparticle composite-containing sheet containing fluororesin-containing particles was again irradiated with ultraviolet light and cured to obtain a nanoparticle composite-containing sheet.

[0098] <Measurement of Lightfastness> The quantum efficiency of the nanoparticle composite-containing sheet containing the obtained fluororesin-containing particles was measured. The lightfastness of the nanoparticle composite-containing sheet was evaluated by the retention rate of the fluorescence quantum efficiency of the nanoparticle composite-containing sheet when the target nanoparticle composite-containing sheet was irradiated with specific single light for a long period of time. The fluorescence quantum efficiency of the above-mentioned nanoparticle composite-containing sheet was measured using a fluorescence quantum efficiency measurement system (QE-2100, manufactured by Otsuka Electronics). The nanoparticle composite-containing sheet was set on a sample stage and exposed to excitation light (single light of 450 nm) to obtain an emission spectrum. The initial fluorescence quantum efficiency of the nanoparticle composite-containing sheet was calculated based on the re-excitation corrected emission spectrum obtained by excluding the re-excitation fluorescence emission spectrum for the portion of fluorescence emitted by re-excitation from the obtained emission spectrum. In a lightfastness test box, the nanoparticle composite-containing sheet was irradiated with single light of 440 nm at 408 mW / cm ２ The sheet was irradiated for 168 hours at an intensity of 1000 kJ / cm. The temperature inside the test box was adjusted to 45°C. 96 hours and 168 hours after the start of irradiation, the sheet was removed from the light resistance test box, and the quantum efficiency was measured in the same manner as described above. The retention rates of the fluorescence quantum efficiency of the nanoparticle composite-containing sheet after 96 hours and 168 hours are shown in Table 12.

[0099]

[0100] The nanoparticle composite-containing sheet containing fluororesin-containing particles composed of a nanoparticle composite, functional particles, and a fluororesin maintained a fluorescence quantum efficiency of 40% or more even after 168 hours.

[0101] 11, 21 Nanoparticle composite 12, 23 Functional particle 22 Fluorine resin 100, 110, 120 Composite particle 200, 210, 220, 230, 240 Fluorine resin-containing particle

Claims

1. A composite particle comprising at least one nanoparticle composite and an aggregate of a plurality of functional particles, wherein the nanoparticle composite is present within an aggregate structure formed by the aggregate of the functional particles, and the nanoparticle composite is held within the aggregate structure by intermolecular forces between the nanoparticle composite and the functional particles.

2. The composite particle of claim 1, wherein the functional particle comprises a silica particle.

3. The composite particle according to claim 1 or 2, wherein the functional particle exhibits a negative surface potential at 25°C and in the pH range of 2 or higher.

4. A composite particle according to any one of claims 1 to 3, wherein the number of functional particles is 4 to 800 for the at least one nanoparticle composite.

5. The composite particle according to any one of claims 1 to 4, wherein the nanoparticle complex comprises a nanoparticle and a ligand, and the ligand has a thiol group as a coordinating group that coordinates with the nanoparticle.

6. Composite particles according to any one of claims 1 to 5, wherein when the composite particles are added to a dispersion medium, at least a portion of the nanoparticle composite and / or the functional particles are redispersible in the dispersion medium.

7. A method for producing composite particles containing at least one nanoparticle composite and an aggregate of a plurality of functional particles, comprising: mixing a nanoparticle composite dispersion in which the nanoparticle composite is dispersed in a dispersion medium with a functional particle dispersion in which functional particles are dispersed in a dispersion medium to prepare a mixed solution; and drying the mixed solution.

8. The method for producing composite particles according to claim 7, wherein the mixed solution is dried in a state in which the mixed solution is in the form of droplets.

9. The method for producing composite particles according to claim 7 or 8, wherein the dispersion medium used in the nanoparticle composite dispersion liquid and the dispersion medium used in the functional particle dispersion liquid are both organic dispersion media.

10. The method for producing composite particles according to any one of claims 7 to 9, wherein the nanoparticle composite dispersion liquid and the functional particle dispersion liquid are compatible with each other.

11. The method for producing composite particles according to any one of claims 7 to 10, wherein the nanoparticle composite and the functional particles are in a dispersed state in the mixed solution.

12. The method for producing composite particles according to any one of claims 7 to 10, wherein at least a portion of the nanoparticle composites and / or the functional particles are aggregated in the mixed solution.

13. A fluororesin-containing particle comprising at least one nanoparticle composite, a plurality of functional particles, and a fluororesin.

14. The fluororesin-containing particles according to claim 13, wherein the plurality of functional particles form an aggregate structure in which the nanoparticle composite is encapsulated.

15. The fluororesin-containing particles according to claim 13 or 14, wherein the functional particles include silica particles.

16. A method for producing fluororesin-containing particles containing at least one nanoparticle composite, a plurality of functional particles, and a fluororesin, comprising: mixing the nanoparticle composite, the functional particles, and the fluororesin in a dispersion medium to prepare a preparation liquid; and drying the preparation liquid.

17. A method for producing fluororesin-containing particles as described in claim 16, wherein, when preparing the preparation liquid, the nanoparticle composite is mixed in the state of a nanoparticle composite dispersion liquid, and the functional particles are mixed in the state of a functional particle dispersion liquid.

18. The method for producing composite particles described in claim 17, wherein, when preparing the preparation liquid, the fluororesin is mixed in the form of a fluororesin dispersion, and the nanoparticle composite dispersion, the functional particle dispersion, and the fluororesin dispersion are compatible with each other.

19. A nanoparticle composite-containing sheet comprising the fluororesin-containing particles according to any one of claims 13 to 15.

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