Particle purification method

Abstract

The present invention provides a particle purification method, comprising: preparing a purification liquid; wherein the purification liquid comprises a first purification liquid and a second purification liquid, and the first purification liquid and the second purification liquid are immiscible with each other; thoroughly mixing a mixed liquid to be purified with the purification liquid, and standing to separate into layers; wherein the mixed liquid comprises ligand-modified particles, free ligands, and a dispersant, wherein the dispersion of the particles in the first purification liquid is greater than that in the second purification liquid, and the dispersion of the ligands in the second purification liquid is greater than that in the first purification liquid; removing the separated layer liquid containing the second purification liquid, extracting the separated layer liquid containing the first purification liquid; and freeze-drying the separated layer liquid to obtain purified particles. The particle purification method provided by the present invention takes into account both the purification purity of the particles and the dispersion effect for subsequent use.

Description

Technical Field

[0001] The present application relates to the display field, and in particular to a particle purification method. Background Art

[0002] As display technology gradually matures, competition in the display industry for specifications based on technologies such as OLED, LCD, and MLED becomes increasingly fierce. The requirements for related materials are increasing year by year, leading to the development of materials with new functions such as refractive index, haze, and transmittance.

[0003] In recent years, with the increasing international energy pressures and the rise of concepts such as low carbon and environmental protection, higher requirements have been placed on the energy efficiency of display technology. Improving the energy efficiency of display devices requires not only improving light source efficiency but also improving light dissipation between film layers, enhancing light extraction between film layers, and regulating the direction of light emission for wide viewing angles. This requires film materials with properties such as refractive index control, patternability, and excellent interlayer adhesion.

[0004] The refractive index of membrane materials is typically controlled by modifying nanoparticles and then dispersing them within the membrane material formulation. The refractive index of the formulation can be controlled by adjusting the particle concentration. However, particle modification produces a large amount of free ligands, which, if not purified, can severely affect the refractive index of the system. Adding a precipitant to precipitate the particles before purification can cause particle aggregation, making it impossible for the modified nanoparticles to disperse within the system. Summary of the Invention

[0005] The present invention provides a particle purification method for purifying ligand-modified particles while ensuring the dispersion effect of the purified particles.

[0006] To solve the above problems, the technical solutions provided by the present invention are as follows:

[0007] The present invention provides a particle purification method, which comprises:

[0008] Prepare a purification liquid; wherein the purification liquid includes a first purification liquid and a second purification liquid, and the first purification liquid and the second purification liquid are immiscible with each other;

[0009] Thoroughly mixing the mixed liquid to be purified with the purified liquid and allowing the mixture to stand for separation; wherein the mixed liquid comprises ligand-modified particles, free ligands, and a dispersant, the dispersion of the particles in the first purified liquid is greater than that in the second purified liquid, and the dispersion of the ligand in the second purified liquid is greater than that in the first purified liquid;

[0010] removing the layered liquid where the second purified liquid is located, and extracting the layered liquid where the first purified liquid is located;

[0011] The layered liquid is freeze-dried to obtain purified particles.

[0012] Optionally, in some embodiments of the present invention, after removing the stratified liquid containing the second purification liquid and extracting the stratified liquid containing the first purification liquid, the particle purification method further comprises:

[0013] adding an equal volume of the second purified liquid to the layered liquid containing the first purified liquid, mixing thoroughly and allowing the mixture to stand for layer separation;

[0014] The layered liquid containing the second purified liquid is removed again, and the layered liquid containing the first purified liquid is extracted.

[0015] Optionally, in some embodiments of the present invention, the volume ratio of the mixed liquid to the purified liquid is 1:1 to 1:5.

[0016] Optionally, in some embodiments of the present invention, the volume ratio of the first purification liquid to the second purification liquid in the purification liquid is 1:0.5 to 1:50.

[0017] Optionally, in some embodiments of the present invention, the polarity of the first purification liquid is greater than the polarity of the particles and the polarity of the dispersant, the polarity of the particles and the polarity of the dispersant are both greater than the polarity of the ligand, and the polarity of the ligand is greater than the polarity of the second purification liquid.

[0018] Optionally, in some embodiments of the present invention, the miscibility of the dispersant with the first purified liquid is better than the miscibility of the dispersant with the second purified liquid.

[0019] Optionally, in some embodiments of the present invention, the dispersant is an alcohol dispersant or a ketone dispersant; the ligand includes one or more of thiol, fatty acid, and fatty amine; and the particles include one or more of SiO2 particles, ZrO2 particles, organic microsphere particles, and quantum dot particles.

[0020] Optionally, in some embodiments of the present invention, the first purification liquid is water.

[0021] Alternatively, in some embodiments of the present invention, the second purified liquid is an alkane or alkene with 6 to 30 carbon atoms.

[0022] Optionally, in some embodiments of the present invention, the second purification liquid is n-hexane or cyclohexane.

[0023] The present invention provides a particle purification method. According to the different polarities and solubilities of the particles and free ligands, a suitable purification liquid is prepared and a liquid separation method is adopted to remove the free ligands and purify the particles to be purified, thereby ensuring the purification purity of the particles. Then, a freeze-drying process is performed to remove the liquid in the layered liquid to obtain dried particles, thereby ensuring the physical and chemical properties of the particles and further ensuring the dispersion effect of the particles in subsequent use, thereby avoiding the problem of direct addition of a precipitant causing the particles to precipitate and aggregate and become unable to be dispersed. The particle purification method provided by the embodiment of the present invention takes into account both the purification purity of the particles and the dispersion effect in subsequent use. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0025] Figure 1 A flow chart of a particle purification method provided in an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of a particle purification method provided by an embodiment of the present invention;

[0027] Figure 3 The infrared spectrum of the upper liquid provided by the embodiment of the present invention;

[0028] Figure 4 This is an infrared spectrum of the lower layer of liquid provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments and / or examples of the present invention. Obviously, the embodiments and / or examples described below are only part of the embodiments and / or examples of the present invention, rather than all the embodiments and / or examples. Based on the embodiments and / or examples in the present invention, all other embodiments and / or examples obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] Directional terms used in this disclosure, such as [upper], [lower], [left], [right], [front], [back], [inner], [outer], and [side], are used solely to refer to directions in the accompanying drawings. Therefore, the directional terms used are intended to illustrate and understand the present disclosure, not to limit it. Terms such as "first," "second," and the like are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referenced. Therefore, a feature designated as "first," "second," and the like may explicitly or implicitly include one or more of such features.

[0031] In view of the problem that the purity and dispersion effect of the existing ligand-modified particles cannot be balanced, the present invention provides a particle purification method to solve the problem.

[0032] In one embodiment, see Figure 1 and Figure 2 , Figure 1 The flowchart of the particle purification method provided by the embodiment of the present invention is shown. Figure 2 Schematic diagram of the particle purification method provided by the embodiment of the present invention. Figure 1 and Figure 2 As shown, the particle purification method provided by the embodiment of the present invention includes:

[0033] Step B1, preparing a purification liquid; wherein the purification liquid includes a first purification liquid and a second purification liquid, and the first purification liquid and the second purification liquid are immiscible with each other;

[0034] Step B2, thoroughly mixing the mixed solution to be purified with the purified solution and allowing the mixture to stand for stratification; wherein the mixed solution comprises the ligand-modified particles, the free ligand, and the dispersant, the dispersion of the particles in the first purified solution is greater than that in the second purified solution, and the dispersion of the ligand in the second purified solution is greater than that in the first purified solution;

[0035] Step B3, removing the layered liquid containing the second purified liquid, and extracting the layered liquid containing the first purified liquid;

[0036] Step B4: freeze-drying the layered liquid to obtain purified particles.

[0037] According to the embodiment of the present invention, based on the differences in polarity and solubility between the particles and the free ligands, a suitable purification liquid is prepared and the free ligands are removed by a liquid separation method to purify the particles to be purified, thereby ensuring the purification purity of the particles; then, through a freeze-drying process, the liquid in the stratified liquid is removed to obtain dry particles, thereby ensuring the physical and chemical properties of the particles, and further ensuring the dispersion effect of the particles in subsequent use, avoiding the problem of direct addition of a precipitant causing the particles to precipitate and aggregate and become unable to be dispersed; the particle purification method provided by the embodiment of the present invention takes into account both the purification purity of the particles and the dispersion effect of subsequent use.

[0038] In one embodiment, the particles are micro-nano sized particles, with a size range of 2 nanometers to 10 microns. The particles include inorganic and organic particle materials. The inorganic particle materials include quantum dot materials, such as CdSe quantum dot materials, InP, ZnSe quantum dot materials, ZnCdS2 quantum dot materials, and ZnS quantum dot materials; the inorganic particle materials also include metal nanoparticles, such as Ag nanoparticles, Au nanoparticles, and Cu nanoparticles; the inorganic particle materials also include other inorganic nanoparticles, such as TiO2, SiO2, ZrO2, and Fe3O4; the inorganic particle materials can also be core-shell materials that combine the above materials, such as CdSe / ZnS and CdSe / SiO2; the inorganic particle materials also include nanoparticles of various shapes, such as mesoporous particles, hollow particles, egg yolk structure particles, nanowires, nanorods, and nanosheets. The organic particle materials include, but are not limited to, organic microspheres, such as star-shaped heteroarm styrene-methyl methacrylate copolymers.

[0039] The ligand is a weakly polar ligand having a long carbon chain structure, one end of which can be physically or chemically connected to the particle, and the other end of which includes a weakly polar group. The ligand includes a silane coupling agent, such as KH-550, KH-570, etc.; the ligand also includes a thiol ligand, preferably an alkylthiol containing 4-14 carbon atoms, such as dodecylthiol, decanethiol, etc.; the ligand also includes a fatty acid ligand, preferably an alkyl carboxylic acid containing 8-16 carbon atoms and an alkenyl carboxylic acid containing 8-16 carbon atoms, such as oleic acid, tetradecanoic acid, octadecanoic acid, etc.; the ligand also includes a fatty amine ligand, preferably an enamine containing 4-18 carbon atoms and an alkylamine containing 4-18 carbon atoms, such as oleylamine, octadecylamine, butylamine, trioctylamine, etc.; the ligand also includes an organophosphorus ligand, such as tri-n-octylphosphine, tri-n-octylphosphine oxide, etc.

[0040] The dispersant is a highly polar dispersant, including organic and inorganic reagents that are liquid at room temperature. The dispersant includes water; the dispersant also includes alcohol dispersants such as methanol, ethanol, isopropanol, etc.; the dispersant also includes lipid dispersants such as ethyl acetate and butyl acetate; the dispersant also includes hydrocarbon dispersants such as pentane, n-hexane, cyclohexane, heptane, octane, octadecene, squalane, etc.; the dispersant also includes ketone dispersants such as acetone, butanone, and methyl isobutyl ketone.

[0041] The ligand-modified particles are dispersed in the dispersant. A large amount of free ligand, unmodified from the particles, is also dispersed in the dispersant. These free ligands act as impurities and affect the refractive index and other properties of the particles. Therefore, the free ligands need to be purified. The mass concentration of the particles in the mixed solution ranges from 0.5% to 50%, preferably from 0.5% to 10%. The mass concentration of the ligand in the mixed solution ranges from 0.05% to 80%. The remainder is the dispersant.

[0042] In a specific embodiment, the particle purification method provided by the embodiment of the present invention is explained in detail, taking the particles as SiO2 particles, the ligand as the dispersant as a silane coupling agent, and the dispersant as ethanol.

[0043] The SiO2 particles have hydroxyl groups on their surfaces, which give them strong polarity. After modification with a silane coupling agent, the polarity of the SiO2 particles decreases slightly, but they still retain a strong polarity, making them easily dispersible in highly polar solvents such as water and ethanol, but difficult to disperse in less polar solvents such as n-hexane. The free silane coupling agent has weak polarity and can be dispersed in water, ethanol, and n-hexane, but its solubility in water and ethanol is lower than its dispersibility in n-hexane.

[0044] Water is used as the first purification liquid, and n-hexane is used as the second purification liquid. The purified liquid is prepared and added. Figure 2 (a1). The volume ratio of water to n-hexane is 1:0.5 to 1:50, preferably 1:0.5 to 1:10. Water and n-hexane are two liquids with greatly different polarities. After the water and n-hexane are mixed and allowed to stand for half a minute, they separate into two layers, the upper layer being the n-hexane with a lower density and the lower layer being the water with a higher density.

[0045] 2 ml to 1 liter of the mixed solution including ethanol, the SiO2 particles, and the silane coupling agent ( Figure 2 (a2)), mixed with 2 ml to 1 liter of the purified solution including water and n-hexane, shaken or stirred for a period of time and then allowed to stand for stratification, such as Figure 2(b). The volume ratio of the mixed liquid to the purified liquid is 1:1 to 1:5. The stirring time is 5 minutes to 30 minutes, and the standing time is 10 minutes to 60 minutes. After standing, the liquid is divided into two layers, the upper liquid includes n-hexane with a lower density, and the lower liquid includes water with a higher density; since the dispersibility of the silane coupling agent in n-hexane is greater than the dispersibility in water or ethanol, the upper liquid also includes free silane coupling agent; since the dispersibility of ethanol in water is greater than the dispersibility in n-hexane, the dispersibility of the SiO2 particles in water is much greater than the dispersibility in n-hexane, therefore, the lower liquid also includes SiO2 particles and ethanol. It should be noted that the volumes of the mixed liquid and the purified liquid are for illustration only and are not intended to be limiting. The volumes of the mixed liquid and the purified liquid can be scaled up in equal proportions.

[0046] Remove the upper layer of n-hexane liquid and retain the lower layer of water liquid, such as Figure 2 (c). Please refer to Figure 3 and Figure 4 , Figure 3 is the infrared spectrum of the upper liquid. Figure 4 is the infrared spectrum of the lower liquid. Figure 3 A large number of characteristic peaks of KH570 can be seen in the upper layer, which proves that there are a large number of functional groups of silane coupling agents in the upper liquid, and further proves that a large amount of free silane coupling agents are separated and removed by n-hexane. Figure 4 Only a very small amount of characteristic peaks of KH570 were detected in the lower layer, which proved that the free silane coupling agent in the lower liquid had been removed.

[0047] Since silane coupling agents are soluble in water and ethanol, a small amount of free silane coupling agent still exists in the lower aqueous layer. After removing the upper n-hexane liquid, an equal volume of n-hexane can be added to the aqueous liquid. The mixture is then mixed, shaken, or stirred for a period of time, and allowed to stand to separate. The upper n-hexane liquid is then removed again to obtain a further purified lower aqueous layer. After repeating this process 0 to 2 times, 80% of the free silane coupling agent is removed.

[0048] The water and ethanol in the lower liquid are removed by freeze drying process to obtain freeze dried powdered SiO2 particles modified with silane coupling agent and a very small amount of free silane coupling agent, such as Figure 2 Middle (d).

[0049] In the particle purification method provided in an embodiment of the present invention, by adjusting the ratio of the dispersant, the first purification liquid, and the second purification liquid, and controlling the number of times the second purification liquid is added, the coverage rate of the ligands on the surface of the purified particles and the content of the impurity ligands can be controlled, thereby controlling the influence of the ligand molecules on the refractive index, curing rate, hardness and other properties of the system.

[0050] In summary, the embodiments of the present invention provide a particle purification method. According to the different polarities and solubilities of the particles and free ligands, the free ligands are removed by preparing a suitable purification liquid using a liquid separation method, and the particles to be purified are purified, thereby ensuring the purification purity of the particles; then, through a freeze-drying process, the liquid in the stratified liquid is removed to obtain dry particles, thereby ensuring the physical and chemical properties of the particles, and further ensuring the dispersion effect of the particles in subsequent use, avoiding the problem of direct addition of a precipitant causing the particles to precipitate and aggregate and become unable to be dispersed; the particle purification method provided by the embodiments of the present invention takes into account both the purification purity of the particles and the dispersion effect of subsequent use.

[0051] The particle purification method provided in the embodiments of the present invention is introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A particle purification method, characterized in that: include: Prepare a purification liquid; wherein the purification liquid includes a first purification liquid and a second purification liquid, and the first purification liquid and the second purification liquid are immiscible with each other; Thoroughly mixing the mixed liquid to be purified with the purified liquid and allowing the mixture to stand for separation; wherein the mixed liquid comprises ligand-modified particles, free ligands, and a dispersant, the dispersion of the particles in the first purified liquid is greater than that in the second purified liquid, and the dispersion of the ligand in the second purified liquid is greater than that in the first purified liquid; removing the layered liquid where the second purified liquid is located, and extracting the layered liquid where the first purified liquid is located; freeze-drying the layered liquid to obtain purified particles; The volume ratio of the mixed liquid to the purified liquid is 1:1 to 1:5; The volume ratio of the first purified liquid to the second purified liquid in the purified liquid is 1:0.5 to 1:50; The dispersant is an alcohol dispersant or a ketone dispersant; The particles include one or more of SiO2 particles, ZrO2 particles, organic microsphere particles, and quantum dot particles; The ligand is a silane coupling agent; The first purification liquid is water; The second purified liquid is an alkane or alkene having 6 to 30 carbon atoms.

2. The particle purification method according to claim 1, wherein After removing the layered liquid where the second purification liquid is located and extracting the layered liquid where the first purification liquid is located, the particle purification method further includes: adding an equal volume of the second purified liquid to the layered liquid containing the first purified liquid, mixing thoroughly and allowing the mixture to stand for layer separation; The layered liquid containing the second purified liquid is removed again, and the layered liquid containing the first purified liquid is extracted.

3. The particle purification method according to claim 1, wherein: The polarity of the first purification liquid is greater than the polarity of the particles and the polarity of the dispersant, the polarity of the particles and the polarity of the dispersant are both greater than the polarity of the ligand, and the polarity of the ligand is greater than the polarity of the second purification liquid.

4. The particle purification method according to claim 3, wherein: The mutual solubility of the dispersant in the first purified liquid is better than the mutual solubility of the dispersant in the second purified liquid.

5. The particle purification method according to claim 1, wherein: The second purification liquid is n-hexane or cyclohexane.

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