Black particles, black electrophoretic particles, methods of preparation and applications

Abstract

The application relates to the technical field of electrophoretic display, in particular to a black particle, a black electrophoretic particle, a preparation method and application. The black particle comprises a mixed-phase component of manganese dioxide, triiron tetroxide and copper oxide, and does not comprise an oxide of chromium, has good hiding power, coloring power and stability, is easier to modify and has performance advantages compared with a copper-chromium black particle in the prior art, has small pollution and is more environmentally friendly. The black particle can be prepared through two-stage sintering and grinding granulation and the like. The black particle is modified through polymer coating to obtain a black electrophoretic particle, the black electrophoretic particle is not prone to agglomeration and settlement in electrophoretic display, has good compatibility with a dispersing agent, good dispersibility and stability, high Zeta potential and large surface charge, and has excellent display effect. The black particle and the black electrophoretic particle can be applied to electrophoretic display.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electrophoretic display, and particularly relates to a black particle, a black electrophoretic particle, a preparation method and application. BACKGROUND

[0002] Electrophoretic display is a light-reflecting bistable display imaging technology realized by using electrophoresis principle. Compared with traditional display technology, it is a flexible electronic display technology with great development potential. For example, electronic paper prepared by electrophoretic display technology can combine the advantages of ordinary paper and electronic display.

[0003] The most important component in electrophoretic display technology is electrophoretic display fluid, which includes electrophoretic particles and dispersion medium. Electrophoretic particles are the core component of electrophoretic display fluid, which are uniformly and stably dispersed in the dispersion medium and can realize image display under the action of external electric field after being charged. In black and white electrophoretic display applications, the pigment in black electrophoretic particles is often inorganic material. After modification of the inorganic material, the black electrophoretic particles can be practically applied. However, the commonly used black inorganic pigment is copper chromium black, but the modification effect of copper chromium black is limited, the number of surface hydroxyl groups is small, and the grafting amount is low. Therefore, the Zeta potential of copper chromium black is low in actual use, which leads to a long response time of electronic paper and is not conducive to the popularization and application of electronic paper. SUMMARY

[0004] The present application aims to provide a black particle, a black electrophoretic particle, a preparation method and application, and aims to solve the problem that copper chromium black in the existing electrophoretic display technology has various defects, which makes the performance of the prepared black electrophoretic particle not ideal and pollutes the environment.

[0005] To achieve the above application purposes, the technical solutions adopted by the present application are as follows:

[0006] In a first aspect, the present application provides a black particle. The black particle includes a mixed phase component of manganese dioxide, ferric oxide and copper oxide, and does not include chromium oxide.

[0007] The black particle of the present application has the above-mentioned mixed phase components, which endows the black particle with good hiding power, excellent coloring power, and extremely strong thermal stability, etc. Compared with the copper chromium black particle of the prior art, there is no serious pollution of heavy metal chromium, and it is more environmentally friendly. In practical application, the hydroxyl content of the black particle after surface treatment is also higher than that of copper chromium black, which is more conducive to the performance advantages of the black particle through subsequent modification. In electrophoretic display, the Zeta potential of the electrophoretic display fluid containing the black particle of the present application is higher than that of the prior art, that is, the repulsive force between the black particles is higher, which can better uniformly disperse and maintain a stable state in the electrophoretic display fluid.

[0008] In a second aspect, the application provides a preparation method of black particles, comprising the following steps:

[0009] The first mixed material including the manganese source, the iron source and the copper source is subjected to a first sintering treatment to obtain a first sintering product;

[0010] The first sintering product is subjected to a grinding treatment to obtain a ground product;

[0011] The ground product is subjected to a granulation treatment and then a second sintering treatment to obtain a second sintering product;

[0012] The second sintering product is subjected to a crushing treatment to obtain the black particles.

[0013] The preparation method of the black particles of the application comprises two sintering treatments, and the first sintering treatment sinters the raw materials into a first sintering product containing manganese, iron and copper oxide components. Then, the first sintering product is subjected to a grinding treatment to control the particle size, a granulation treatment to obtain particles, a second sintering treatment to further promote the shrinkage of the particles, and finally a crushing treatment to obtain the black particles. The prepared black particles have good hiding power, excellent coloring power, and excellent thermal stability. In practical applications, the hydroxyl content of the surface-treated black particles is higher, and the performance advantages of the black particles can be better exerted. The black particles have a high Zeta potential and good display effect in electrophoretic display. Meanwhile, the preparation method of the black particles of the application is controllable, and the prepared black particles are stable in properties and do not cause serious pollution of heavy metal chromium, and are more environmentally friendly.

[0014] In a third aspect, the application provides black electrophoretic particles. The black electrophoretic particles comprise a core and a shell layer covering the core, the material of the core comprises the black particles of the application or the black particles prepared by the preparation method of the application, and the material of the shell layer comprises a polymer.

[0015] The black electrophoretic particles of the application have a core-shell structure, the material of the core comprises the black particles, and the material of the shell layer comprises a polymer, i.e., the black electrophoretic particles of the application comprise organic coated and modified black particles, which are stable in properties, do not cause serious pollution of heavy metal chromium, are more environmentally friendly, are not easy to agglomerate and settle in electrophoretic display liquid, have good compatibility with dispersants, good dispersibility and stability, a high Zeta potential, and are more easily combined with charge control agents in use, thereby increasing the charged amount of the black electrophoretic particles and improving the response speed, and having excellent display effect.

[0016] In a fourth aspect, the application provides a preparation method of black electrophoretic particles, comprising the following steps:

[0017] The black particles comprise the black particles of the application or the black particles prepared by the preparation method of the application.

[0018] The black particles are mixed with polymer monomers for a second mixing process and a polymerization reaction process to obtain black electrophoretic particles.

[0019] The preparation method of the black electrophoretic particles of the present application provides black particles first, and then polymerizes the polymer monomers to coat the black particles, thereby obtaining black electrophoretic particles with core-shell structure. The prepared black electrophoretic particles have the properties of not easy to aggregate and settle, good dispersibility and stability, high Zeta potential, high charge capacity, fast response speed, and good display effect. The preparation method is controllable, and the prepared black electrophoretic particles have stable properties.

[0020] In a fifth aspect, the present application provides the application of the black particles in electrophoretic display.

[0021] The black particles of the present application have the above-mentioned properties, and can be better inorganic or organic modified compared with copper chromium black. The black particles are not easy to aggregate and settle to form precipitates, and are uniformly dispersed, which can improve the charge capacity, improve the response speed in the electric field, and improve the electrophoretic display effect.

[0022] In a sixth aspect, the present application provides the application of the black electrophoretic particles in electrophoretic display.

[0023] The black electrophoretic particles of the present application have the above-mentioned properties, and therefore are not easy to aggregate and settle in electrophoretic display, and are uniformly dispersed, which can improve the charge capacity, improve the response speed in the electric field, and improve the electrophoretic display effect.

[0024] In a seventh aspect, the present application provides an electronic paper. The electronic paper comprises the black electrophoretic particles, and the black electrophoretic particles comprise the above-mentioned black electrophoretic particles, or are prepared by the above-mentioned preparation method.

[0025] The electronic paper of the present application comprises the above-mentioned black electrophoretic particles, and therefore the black electrophoretic particles in the electronic paper are not easy to aggregate and settle, can be better dispersed in the dispersant and maintain a steady state, can improve the charge capacity, improve the response speed in the electric field, and improve the electrophoretic display effect. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 is a schematic diagram of the preparation method of the black particles of the present application:

[0028] Figure 2 This is a schematic diagram of the method for preparing black electrophoretic particles according to an embodiment of this application;

[0029] Figure 3 This is an SEM image of the black particles provided in Embodiment A1 of this application;

[0030] Figure 4 This is a SEM image of the black electrophoretic particles provided in Embodiment B1 of this application. Detailed Implementation

[0031] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0032] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0033] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0034] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0035] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0036] The weight of the related components mentioned in the embodiment specification of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of each component. Therefore, as long as the content of the related components in the embodiment specification of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the embodiment specification of the present application. Specifically, the mass in the embodiment specification of the present application can be μg, mg, g, kg, and other mass units commonly known in the chemical industry.

[0037] The terms "first", "second" are only for descriptive purposes and are used to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the present application, the first XX can also be referred to as the second XX, and similarly, the second XX can also be referred to as the first XX. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features.

[0038] The first aspect of the embodiment of the present application provides a black particle. The black particle of the embodiment of the present application includes a mixed phase component of manganese dioxide, triiron tetroxide and copper oxide, and does not include chromium oxide.

[0039] The material of the black particle of the embodiment of the present application (hereinafter can be referred to as manganese-iron black) includes three components of manganese dioxide phase (manganese is +4 valence), triiron tetroxide phase (iron is 1 / 3 +2 valence and 2 / 3 +3 valence), and copper oxide phase (copper is +2 valence), and is a mixed phase material, rather than a mixture of the three components. Unlike the copper-chromium black commonly used in the prior art, the manganese-iron black does not include heavy metal chromium element oxides, oxide phases (such as chromous oxide CrO, dichromic oxide Cr2O3, and chromic oxide CrO3), so there is no serious pollution of heavy metal chromium, and it is more environmentally friendly. According to research, compared with copper-chromium black, the black particles prepared by manganese-iron black have good hiding power, excellent coloring power, and excellent thermal stability, etc., so they can be used as black inorganic pigments in electrophoretic display. In addition, in practical applications, the hydroxyl content of the black particle surface after treatment will also be higher than that of copper-chromium black, which is more conducive to exerting the performance advantages of the black particle. In electrophoretic display, the copper-chromium black particles are replaced by the black particles of the embodiment of the present application, and the Zeta potential of the electrophoretic display liquid is significantly improved, the repulsion between the black particles is higher, and the black particles can be better dispersed and kept in a stable state in the electrophoretic display liquid.

[0040] In some embodiments, the specific surface area of the black particle can be 15 m 2 / g~25 m 2 / g, the particles with relatively large specific surface area are more conducive to modification in practical applications, for example, the surface hydroxyl groups can be more by alcohol treatment, which is more conducive to surface modification, improves the compatibility with dispersants, and increases the dispersion degree and stability of electrophoretic particles in the dispersant, thereby improving the display effect of black particles in electrophoretic display. In exemplary embodiments, the specific surface area of black particles can include, but is not limited to, 15 m 2 / g, 18 m 2 / g, 20 m 2 / g, 22 m 2 / g, 25 m 2 / g.

[0041] In some embodiments, the particle size of the black particles can be 0.5 μm to 1.8 μm, and the density can be 4.5 g / cm 3 to 5.5 g / cm 3 The particle size and density of the black particles in this range are conducive to controlling the particle size and density of electrophoretic particles after modification of the black particles in practical applications, preventing the electrophoretic particles from agglomerating and settling in the dispersion medium, improving the compatibility with the dispersion medium, and increasing the dispersion degree and stability of electrophoretic particles in the dispersant.

[0042] In some embodiments, the light absorption rate of the black particles can be ≥ 80%. The black particles with sufficient light absorption rate have higher black state values, which improves the contrast with white particles in practical applications and improves the effect of electrophoretic display. In exemplary embodiments, the light absorption rate of the black particles can include, but is not limited to, 80%, 84%, 88%, and 90%.

[0043] In some embodiments, the mass percentage of manganese dioxide, triiron tetroxide, and copper oxide in the mixed-phase component can be as follows, based on 100% of the total mass of the black particles:

[0044] Manganese dioxide 1.0% to 80%

[0045] Triiron tetroxide 10% to 90%

[0046] Copper oxide 0.1% to 80%.

[0047] The mass percentage of the three mixed-phase components in the black particles of the embodiments of the present application is in the above range, and the hiding power, coloring power, thermal stability, and light absorption rate of the black electrophoretic particles are further improved. In exemplary examples, the mass percentage of manganese dioxide can include but is not limited to 1.0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, and 80%; the mass percentage of magnetite can include but is not limited to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90%; and the mass percentage of copper oxide can include but is not limited to 0.1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, and 80%.

[0048] In some embodiments, the mass percentage of the mixed-phase components is as follows, based on 100% of the total mass of the black particles:

[0049] Zinc oxide 0.1% to 1.0%.

[0050] The research shows that when the black particles further include a certain mass ratio of zinc oxide phase, the coloring power and color light and other performances of the black particles are improved. In exemplary examples, the mass percentage of the zinc oxide phase can include but is not limited to 0.1%, 0.2%, 0.5%, 0.7%, and 1%.

[0051] The second aspect of the embodiments of the present application provides a preparation method of black particles. In some embodiments, the preparation method of the black particles is combined with the preparation method of the black particles. Figure 1 The preparation method of the black particles of the embodiments of the present application includes the following steps:

[0052] S01. A first mixed treatment is performed on manganese source, iron source, and copper source, and then a first sintering treatment is performed to obtain a first sintering product;

[0053] S02. The first sintering product is ground to obtain a ground product;

[0054] S03. The ground product is granulated and then a second sintering treatment is performed to obtain a second sintering product;

[0055] S04. The second sintering product is crushed to obtain black particles.

[0056] The preparation method of the embodiments of the present application prepares the black particles containing mixed-phase components from manganese source, iron source, and copper source through two-stage sintering treatment, so that the prepared black particles have good hiding power, excellent coloring power, and extremely strong thermal stability. In actual applications, the surface treatment has a higher hydroxyl content, and the performance advantages of the black particles can be better exerted. The black particles have high Zeta potential and good display effect in electrophoretic display. The display effect is good, the preparation process is controllable, the prepared black particles are stable in properties, and are more environmentally friendly.

[0057] Step S01:

[0058] In step S01, the manganese source, the iron source and the copper source are mixed to form a mixture, and preferably a uniformly dispersed mixture, thereby forming a black particle precursor containing manganese, iron and copper elements, which is used to prepare the mixed-phase black particles. In some embodiments, the manganese source can include at least one of manganese dioxide, manganese carbonate, manganese nitrate, manganese sulfate, and manganese chloride; the iron source can include at least one of magnetite, ferrous sulfate, iron nitrate, and iron chloride; and the copper source can include at least one of copper oxide, copper nitrate, basic copper carbonate, and copper hydroxide.

[0059] In some embodiments, the manganese source, the iron source and the copper source can be mixed in a mass ratio of 1-80:10-90:0.1-80 of manganese dioxide, magnetite and copper oxide contained in the black particles. Controlling the raw materials to be mixed in a mass ratio of the mixed-phase materials contained in the black particles can further improve the hiding power, coloring power, thermal stability and light absorption rate of the prepared black electrophoretic particles. In some embodiments, the mass ratio can include, but is not limited to, (1 or 20 or 40 or 60 or 80):(10 or 30 or 50 or 70 or 90):(0.1 or 1 or 10 or 30 or 50 or 60 or 80).

[0060] In some embodiments, the manganese source is manganese dioxide, the iron source is magnetite, and the copper source is copper oxide. According to research, in order to prepare black particles containing three kinds of oxides, the raw materials are selected to be the oxides of manganese, iron and copper for the first mixing process, which can further simplify the preparation process, improve production efficiency, increase the yield of the prepared black particles, and stabilize the properties of the black particles.

[0061] According to the mixed-phase components of the required black particles, a zinc source can also be added in the first mixing process. The zinc source can include, but is not limited to, zinc oxide, zinc chloride, zinc sulfate, etc. The addition of the zinc source can further improve the coloring power, color light and other properties of the prepared black particles.

[0062] The first sintering process in step S01 can sinter the manganese source, the iron source and the copper source into a first sintered product containing manganese, iron and copper oxide components, so that the phases of the components in the material are initially formed.

[0063] In some embodiments, when the manganese source is manganese dioxide, the iron source is magnetite, and the copper source is copper oxide, the first sintering process can be performed at a temperature of 900-1100℃. In exemplary embodiments, the temperature can include, but is not limited to, 900℃, 950℃, 1000℃, 1050℃, and 1100℃. The temperature rising time can be 20-28 hours, and the sintering holding time can be 8-12 hours. When the manganese source, the iron source, and the copper source are other components, the first sintering temperature can be adjusted by those skilled in the art. In addition, when the above-mentioned raw materials include non-oxides, the sintering can be performed in an oxygen-containing atmosphere to form an oxide-containing component phase.

[0064] Step S02:

[0065] The grinding process can refine the first sintered product and control its particle size, which is beneficial for further processing in subsequent preparation steps. The grinding method can be a ball milling method, for example, the first sintered product is mixed with water to form a slurry for wet ball milling, and then sieved and sand milled to reduce the particle size.

[0066] Step S03:

[0067] The granulation process can make the ground product into granules, which is beneficial for further processing in subsequent preparation steps. For example, when the ground product is in the form of a slurry, the granulation process can be evaporation, crushing, or directly granulated by spray drying. In addition, a mineralizer can also be added to the ground product to improve the effect of the second sintering process.

[0068] The second sintering process is a further secondary low-temperature sintering process of the ground product, which can inhibit the excessive growth of crystals, promote the shrinkage of material particles, reduce the uneven distribution of particle size, and obtain the desired second sintered product, including black particles in the form of powder and agglomerates. The second sintering process can be performed at a temperature of 700-780℃. In exemplary embodiments, the temperature can include, but is not limited to, 700℃, 730℃, 750℃, and 780℃. The temperature rising time can be 20-28 hours, and the sintering holding time can be 8-12 hours.

[0069] Step S04:

[0070] The crushing process can crush the agglomerated regions or larger particles in the second sintered product into powder, and obtain black particles suitable for practical application. For example, the crushing process can be performed by an air flow crushing method.

[0071] The third aspect of the embodiments of the present application provides a black electrophoretic particle. The black electrophoretic particle of the embodiments of the present application includes a core and a shell layer covering the core, the material of the core includes the black particles of the above-mentioned embodiments or the black particles prepared by the preparation methods of the above-mentioned embodiments, and the material of the shell layer includes a polymer.

[0072] The black electrophoretic particles of the embodiments of the present application have a core-shell structure, the core material includes the black particles described above, and the shell material includes a polymer, i.e., the black particles are modified by an organic coating. Such black electrophoretic particles are stable in properties, do not have serious pollution of heavy metal chromium, and are more environmentally friendly. As shown in FIG. 1, because the density of the black particles is generally higher than that of the dispersant in actual applications, the black particles will settle and agglomerate, Figure 3 as shown in FIG. 2, and the particles can be clearly seen to be stacked in the box. As shown in FIG. 3, the black particles modified by the polymer have a reduced density, the density of the black electrophoretic particles is close to that of the dispersant, the particle agglomeration and deposition are reduced, the surface becomes lipophilic and hydrophobic, and thus the dispersibility and stability of the black particles in the organic dispersant are improved in many aspects. In actual applications, the black electrophoretic particles can be more easily combined with the charge control agent, the surface charge of the particles is significantly increased, the response speed under the action of the electric field is improved, the Zeta potential of the electrophoretic display liquid can be improved, and excellent display effects can be achieved. Figure 3 Figure 4 In some embodiments, the grafting rate of the surface of the core to the polymer can be 10% to 30%. The grafting rate represents the mass proportion of the organic substance adsorbed or bonded to the surface of the black particles. The organic substance grafted to the surface of the core can reduce the density of the black electrophoretic particles, so that the particle density is close to that of the dispersant, the particles can be better suspended in the dispersant, and the particle deposition is reduced. In addition, the long chain of the grafted organic substance can form steric hindrance to prevent particle agglomeration and deposition. The stability of the core-shell structure can also be improved. In exemplary embodiments, the grafting rate of the organic polymer on the surface of the core can include but is not limited to 10%, 15%, 20%, 25%, and 30%.

[0073] In some embodiments, the Zeta potential of the black electrophoretic particles can be 30 mV to 55 mV. Controlling the Zeta potential of the black electrophoretic particles of the black particles after modification in this range is conducive to the stability of the electrophoretic system and the realization of the bistability of the electrophoretic display. In addition, the electron transfer rate is proportional to the Zeta potential, and the Zeta potential is controlled in this range, the electron transfer rate is stable and fast, which is conducive to the improvement of the response speed of the black electrophoretic particles. In exemplary embodiments, the Zeta potential of the black electrophoretic particles can include but is not limited to 30 mV, 35 mV, 40 mV, 50 mV, and 55 mV.

[0074] In some embodiments, the polymer can be polymerized from at least one monomer including methyl methacrylate, butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, acrylamide, methyl acrylate, styrene, and divinylbenzene. The inventors have found that the polymer polymerized from the monomers has a good modification effect when used as the shell layer, can give the black electrophoretic particles a suitable density, and improve the dispersibility and stability in the dispersant.

[0075] In some embodiments, the polymer can be polymerized from at least one monomer including methyl methacrylate, butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, acrylamide, methyl acrylate, styrene, and divinylbenzene. The inventors have found that the polymer polymerized from the monomers has a good modification effect when used as the shell layer, can give the black electrophoretic particles a suitable density, and improve the dispersibility and stability in the dispersant.​

[0076] In some embodiments, the polymer can be grafted on the surface of the core body through a coupling agent. The grafting of the polymer on the surface of the core body through the coupling agent is conducive to improving the bonding force between the shell layer and the surface of the core body, making the core-shell structure more firm, improving the stability of the black electrophoretic particle, improving the above-mentioned coating modification effects such as density control, specific surface area, and improving the display effect of the black electrophoretic particle in application.

[0077] The fourth aspect of the embodiments of the present application provides a preparation method of a black electrophoretic particle. In some embodiments, the preparation method of the black electrophoretic particle is combined with the above-mentioned preparation method of the black electrophoretic particle. Figure 2 The preparation method of the black electrophoretic particle of the embodiments of the present application comprises the following steps:

[0078] S05. Providing a black particle; the black particle comprises the black particle of each of the above-mentioned embodiments or is prepared by the preparation method of each of the above-mentioned embodiments;

[0079] S06. Performing a second mixing treatment on the black particle and a polymer monomer and performing a polymerization reaction treatment to obtain a black electrophoretic particle.

[0080] The preparation method of the black electrophoretic particle of the embodiments of the present application can prepare a black electrophoretic particle with a core-shell structure by first providing a black particle and then performing a polymerization reaction treatment on a polymer monomer to coat the black particle, so that the prepared black electrophoretic particle has the properties of not being easy to agglomerate and settle, good dispersibility and stability, high Zeta potential, can improve the charged amount, fast response speed, good display effect, and the like. The preparation method is controllable, and the prepared black electrophoretic particle has stable properties.

[0081] Step S05:

[0082] Providing a black particle is a preparation step of taking it as a core body for subsequent modification. The black particle is specifically the black particle of the above-mentioned embodiments of the present application. The black particle does not contain heavy metal chromium elements, has no serious pollution, is more environmentally friendly, has good hiding power, coloring power, and stability, and has the advantages of being an inorganic pigment.

[0083] Step S06:

[0084] Step S06 can polymerize the polymer monomer into a polymer and form a shell layer to coat and modify the core body, so that the black electrophoretic particle has the above-mentioned excellent properties, and the long chain of the formed polymer can also form steric hindrance to further prevent particle agglomeration and settlement.

[0085] In some embodiments, the temperature of the polymerization treatment can be between 80°C and 140°C, at which the polymerization reaction can proceed with less side reactions, high yield, and high reaction rate. In exemplary embodiments, the temperature of the polymerization treatment can include, but is not limited to, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, and 140°C. The reaction time can be between 8 hours and 12 hours.

[0086] In some embodiments, the polymer monomer and the black particles can be mixed in a mass ratio of 0.5 to 3:1. Controlling the ratio of the polymer monomer and the black particles in this range can improve the adhesion of the polymer, so that the shell layer can sufficiently cover the core of the black electrophoretic particles, thereby forming a complete organic shell structure. If the amount of the polymer is too large, the black electrophoretic particles can be easily converted into pure polymer particles. If the amount of the polymer is too small, the coverage of the black electrophoretic particles can be too low, and the modification effect can be limited. The modified particles can form a regular spherical shape, and the apparent density of the particles can be significantly reduced. The surface of the particles can be changed to be lipophilic and hydrophobic, which can improve the dispersion stability of the particles in the organic medium. The surface charge of the particles can be significantly increased, and the modified particles can be firmly coated with the polymer. The electrophoretic display device prepared using the modified particles can have a long service life. In exemplary embodiments, the mass ratio of the polymer monomer and the black particles can include, but is not limited to, 0.5:1, 1:1, 2:1, and 3:1.

[0087] In some embodiments, the polymer monomer can be mixed with the surface modification product in a solution. The concentration of the solution can be between 0.5 g / mL and 5.0 g / mL. The polymer monomer can be uniformly dispersed in the solution by dissolving the polymer monomer in an organic solvent to prepare a solution with a concentration in this range. The polymer monomer can be mixed with the black particles in the solution and subjected to a polymerization treatment, which can form a shell layer with a uniform thickness and sufficiently cover the core of the black particles, thereby improving the modification effect. If the concentration of the solution is too high, the polymer monomer can be polymerized into a whole piece, which can not achieve the coating effect. If the concentration of the solution is too low, the coverage and the modification effect can be limited. In exemplary embodiments, the concentration of the solution can include, but is not limited to, 0.5 g / mL, 0.6 g / mL, 1.0 g / mL, 2.0 g / mL, 3.0 g / mL, 4.0 g / mL, and 5.0 g / mL. The polymer monomer can include at least one of methyl methacrylate, butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, acrylamide, methyl acrylate, styrene, and divinyl benzene.

[0088] In some embodiments, an initiator may also be added to the mixture in the second mixing treatment. The initiator can promote the polymerization of polymer monomers and improve the efficiency of shell formation. The initiator and polymer monomers can be polymerized at a mass ratio of 0.005 to 0.05:1. Controlling the mass ratio of the two is beneficial for the shell formed during the polymerization reaction to fully coat the core, thus improving the modification effect. When the amount of initiator is small, the coating rate is difficult to guarantee; when the amount of initiator is excessive, cross-linking easily forms between polymer chains, making it difficult to form regular spherical core-shell particles, thus potentially affecting the modification effect. In exemplary examples, the mass ratio may include, but is not limited to, 0.005:1, 0.01:1, 0.03:1, and 0.05:1. The initiator may include at least one of azo chain initiators, organic peroxide initiators, and oil-soluble redox chain initiators, specifically at least one of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile, benzoyl peroxide (BPO), dodecyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl peroxide, tert-butyl peroxybenzoate, diisopropyl peroxide, dicyclohexyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide (BPO), and dicumyl peroxide. Furthermore, the initiation method for the polymerization reaction may also include, but is not limited to, photoinitiation.

[0089] In some embodiments, before the second mixing treatment of the black particles and polymer monomers in step S06, the following steps may also be included:

[0090] S061: Surface modification treatment is applied to the black particles.

[0091] Step S061 involves surface treatment of the black particles, which enhances their surface activity, improves their compatibility with polymer monomers, and mitigates the interfacial interaction between the black particles and polymer monomers. This promotes polymer coating of the core in subsequent steps, ensuring the particles are completely encapsulated within the polymer. Furthermore, grafting polymer monomers onto the modified core surface, thereby adsorbing them onto the core surface, further strengthens the bond between the shell and the core, resulting in a more robust core-shell structure, improved stability of the black electrophoretic particles, and enhanced modification of the organically coated core.

[0092] In some embodiments, the surface modification treatment can be performed by a coupling agent or a surface modifier. The coupling agent can be a silane or a phthalate coupling agent to ensure the surface modification effect, improve the coating effect, and make the core-shell structure more stable. In exemplary embodiments, the coupling agent can include at least one of 3-aminopropyl triethoxysilane, γ-(2,3-epoxypropoxy) propyl trimethoxysilane, γ-methacryloyloxy propyl trimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl methyl dimethoxysilane, γ-aminoethyl aminopropyl trimethoxysilane, and vinylbenzyl aminoethyl aminopropyl trimethoxysilane hydrochloride.

[0093] In some embodiments, the surface modification treatment can include a third mixing treatment of the silane coupling agent and the black particles. The third mixing treatment can be to disperse the black particles in an organic solvent, add a mixture of the silane coupling agent and water (the ratio can be 1:0.1-1:10), and obtain the surface modification product after stirring. Of course, the surface modification product can be further centrifuged, washed, dried, and ground to facilitate the subsequent treatment. The temperature of the surface modification treatment can be 70-110°C (for example, 70°C, 85°C, 100°C, or 110°C), which can better promote the reaction between the silane coupling agent and the surface of the black particles in the mixing treatment of the silane coupling agent and the black particles, improve the modification effect, and the reaction time can be 8-16 hours. The black particles and the silane coupling agent can be mixed at a mass ratio of 0.2-5:1 to improve the modification effect. In exemplary embodiments, the mass ratio of the black particles to the silane coupling agent can include, but is not limited to, 0.2:1, 0.5:1, 1:1, 3:1, or 5:1.

[0094] The fifth aspect of the embodiments of the present application provides an application of the black particles in electrophoretic display.

[0095] The black particles of the embodiments of the present application have the above-mentioned properties, and can be better inorganic or organic modified compared to copper-chromium black. The black particles are not easy to aggregate and settle to form precipitates in the application in electrophoretic display, are uniformly dispersed, have good stability, have high Zeta potential, have increased charge, have fast response speed, and can improve the electrophoretic display effect.

[0096] The sixth aspect of the embodiments of the present application provides an application of the black electrophoretic particles in electrophoretic display.

[0097] The black electrophoretic particles of the embodiments of the present application have the above-mentioned properties, and thus are not easy to aggregate and settle in the application in electrophoretic display, are uniformly dispersed, have good stability, have high Zeta potential, have increased charge, have fast response speed, can improve the electrophoretic display effect, and improve the service life of the coated modified black electrophoretic particles.

[0098] The seventh aspect of the embodiments of the present application provides an electronic paper. The electronic paper comprises black electrophoretic particles, wherein the black electrophoretic particles comprise the black electrophoretic particles in the above embodiments or are prepared by the preparation methods in the above embodiments.

[0099] The electronic paper in the embodiments of the present application comprises the black electrophoretic particles, so the black electrophoretic particles in the electronic paper are not easy to aggregate and settle, can be better dispersed in the dispersant and kept in a stable state, the charge amount is significantly improved, the response speed under the action of an electric field is obviously improved, and the display device containing the electronic paper in the embodiments of the present application can clearly and sensitively realize black and white display. In the electronic paper in the embodiments of the present application, white electrophoretic particles, a dispersant, a stabilizer, a charge control agent and other components can also be included. The charge control agent makes the surface of the electrophoretic particles charged, improves the electrophoretic mobility and Zeta potential of the electrophoretic particles in the dispersing medium, and at the same time, maintains the dispersion stability of the particles by using the repulsion effect of the same charge, and improves the response speed under the electric field. The white electrophoretic particles and the black electrophoretic particles are respectively colored in white and black. The stabilizer can improve the stability of each component in the electronic paper, especially the black electrophoretic particles and the white electrophoretic particles.

[0100] The embodiments are described below in combination with specific examples.

[0101] A. Black particles and preparation methods thereof

[0102] Embodiment A1

[0103] The black particles in the embodiment comprise mixed-phase components in the following mass ratio: 25.6% manganese dioxide, 16.6% copper oxide and 57.8% ferriferrous oxide.

[0104] The preparation method of the black particles in the embodiment comprises the following steps:

[0105] S1. The raw material mixture of manganese dioxide, copper oxide and ferriferrous oxide in the above mass ratio is calcined at a high temperature of 900-1000°C for 10 hours;

[0106] S2. After high-temperature calcination, the product is mixed with water in a slurry in a ratio of 1:1, wet ball milling is performed, 325 mesh screening is performed, and sand milling is performed on the screened slurry until the particle size of the pigment is reduced;

[0107] S3. The sand-milled slurry is added to a mineralizer and stirred, and then spray drying is performed on the slurry. After spray drying, secondary firing is performed, and the product is calcined at a high temperature of 700-780°C for 10 hours;

[0108] S4. The product of the secondary firing is subjected to jet milling to obtain black particles.

[0109] Embodiment A2

[0110] The difference between the black particles of this example and example Al is only that the mixed phase component is: 46.3% manganese dioxide, 20.2% copper oxide, 33.5% magnetite.

[0111] The preparation method step S1 is also adjusted accordingly, and the temperature of the first sintering treatment is changed to 950°C to 1050°C.

[0112] Example A3

[0113] The difference between the black particles of this example and example Al is only that the mixed phase component is: 46.3% manganese dioxide, 20.2% copper oxide, 33.5% magnetite.

[0114] The preparation method step S1 is also adjusted accordingly, and the temperature of the first sintering treatment is changed to 950°C to 1050°C.

[0115] Example A4

[0116] The difference between the black particles of this example and example Al is only that the mixed phase component is: 46.3% manganese dioxide, 20.2% copper oxide, 33.5% magnetite.

[0117] The preparation method step S1 is also adjusted accordingly.

[0118] Example A5

[0119] The difference between the black particles of this example and example Al is only that the mixed phase component is: 46.3% manganese dioxide, 20.2% copper oxide, 33.5% magnetite.

[0120] The preparation method step S1 is also adjusted accordingly.

[0121] Example A6

[0122] The difference between the black particles of this example and example Al is only that the mixed phase component is: 46.3% manganese dioxide, 20.2% copper oxide, 33.5% magnetite.

[0123] The preparation method step S1 is also adjusted accordingly.

[0124] Example A7

[0125] The difference between the black particles of this example and example Al is only that the mixed phase component is: 46.3% manganese dioxide, 20.2% copper oxide, 33.5% magnetite.

[0126] The preparation method step S1 is also adjusted accordingly.

[0127] Example A8

[0128] The black particles of this example differ from example Al only in that the mixed phase component is: 15.7% manganese dioxide, 74.1% copper oxide, 10.2% magnetite.

[0129] The preparation method step S1 is also adjusted accordingly.

[0130] Example A9

[0131] The black particles of this example differ from example Al only in that the mixed phase component is: 15.7% manganese dioxide, 74.1% copper oxide, 10.2% magnetite.

[0132] The preparation method step S1 is also adjusted accordingly.

[0133] Comparative example Al

[0134] This comparative example provides copper-chromium black particles comprising a mixed phase component in the following mass proportions: 43.3% dichromium trioxide, 35.8% manganese dioxide, 20.9% copper oxide.

[0135] Preparation method of copper-chromium black particles:

[0136] A mixture of the above mass proportions of dichromium trioxide, manganese dioxide, and copper oxide is stirred at high speed for 3 h at 1100 r / min, spray dried, and then cooled and pulverized after being held at 1100 °C for 5 h to 8 h to obtain copper-chromium black particles.

[0137] Comparative example A2

[0138] The copper-chromium black particles of this comparative example differ from comparative example Al only in that the mixed phase component is: 24.9% dichromium trioxide, 19.8% manganese dioxide, 55.3% copper oxide.

[0139] The preparation method step S1 is also adjusted accordingly.

[0140] Comparative example A3

[0141] The particles of this comparative example differ from example Al only in that the mixed phase component is: 37.2% manganese dioxide, 62.8% copper oxide.

[0142] The preparation method step S1 is also adjusted accordingly.

[0143] Comparative example A4

[0144] The particles of this comparative example differ from example Al only in that the mixed phase component is: 37.2% manganese dioxide, 62.8% magnetite.

[0145] The preparation method step S1 is also adjusted accordingly.

[0146] B. Black electrophoretic particles and a method for preparing the same

[0147] Example B1

[0148] The black electrophoretic particles of this example are of core-shell structure, the material of the core is the black particles provided in Example Al, the material of the shell is the polymer of stearyl methacrylate, and the shell coats the core.

[0149] The method for preparing the black electrophoretic particles of this example comprises the following steps:

[0150] S5. 100 g of the black particles of Example Al is provided;

[0151] S6. 400 g of toluene is added into a beaker, 100 g of the black particles is added, and after stirring, a γ-aminoethyl aminopropyl trimethoxysilane / γ-methacryloyloxy propyl trimethoxysilane composition (silane coupling agent) and water (35 g / 65 g) are added, the mixture is stirred and uniformly mixed, the temperature is raised to 80 °C, and the reaction is carried out for 10 h. After the reaction is completed, the product is poured into a centrifugal bottle, washed by centrifugation, and dried to obtain a surface-modified product;

[0152] S7. The surface-modified product and 300 g of toluene are uniformly mixed and then transferred into a round-bottom flask for stirring. Then, 210 g of stearyl methacrylate (polymer monomer) is added, and then a solution of azobisisobutyronitrile / toluene (4.8 g / 140 g) is added dropwise as an initiator. The temperature is raised to 90 °C, and the organic polymerization is carried out for 8 h. After the reaction is completed, the product is collected by washing with toluene by centrifugation to obtain black electrophoretic particles.

[0153] Example B2

[0154] The black electrophoretic particles of this example are different from those of Example Bl only in that the material of the core is the black particles provided in Example A2.

[0155] In step S5 of the preparation method, corresponding adjustments are also made, and in addition, the silane coupling agent is changed to 3-aminopropyl triethoxysilane.

[0156] Example B3

[0157] The black electrophoretic particles of this example are different from those of Example Bl only in that the material of the core is the black particles provided in Example A3.

[0158] In step S5 of the preparation method, corresponding adjustments are also made, and in addition, the silane coupling agent is changed to N-(β-aminoethyl)-γ-aminopropyl methyl dimethoxysilane.

[0159] Example B4

[0160] The black electrophoretic particles of this example are different from those of Example Bl only in that the material of the core is the black particles provided in Example A4.

[0161] The preparation process step S5 is also adjusted accordingly, and in addition the polymer monomer is changed to methyl methacrylate.

[0162] Example B5

[0163] The black electrophoretic particles of this example differ from example B1 only in that the material of the core is the black particles provided in example A5.

[0164] The preparation process step S5 is also adjusted accordingly, and in addition the polymer monomer is changed to isooctyl methacrylate.

[0165] Example B6

[0166] The black electrophoretic particles of this example differ from example B1 only in that the material of the core is the black particles provided in example A6.

[0167] The preparation process step S5 is also adjusted accordingly, and in addition the polymer monomer is changed to methyl acrylate.

[0168] Example B7

[0169] The black electrophoretic particles of this example differ from example B1 only in that the material of the core is the black particles provided in example A7.

[0170] The preparation process step S5 is also adjusted accordingly, and in addition the polymer monomer is changed to divinyl benzene.

[0171] Example B8

[0172] The black electrophoretic particles of this example differ from example B1 only in that the material of the core is the black particles provided in example A8.

[0173] The preparation process step S5 is also adjusted accordingly.

[0174] Example B9

[0175] The black electrophoretic particles of this example differ from example B1 only in that the material of the core is the black particles provided in example A9.

[0176] The preparation process step S5 is also adjusted accordingly.

[0177] Comparative Example B1

[0178] This comparative example provides copper-chrome black electrophoretic particles, which differ from example B1 only in that the material of the core is the copper-chrome black particles provided in comparative example A1.

[0179] The preparation process step S5 is also adjusted accordingly.

[0180] Comparative Example B2

[0181] The comparative example provides copper-chromium black electrophoretic particles, which differ from example B1 only in that the material of the core is the copper-chromium black particles provided in comparative example A2.

[0182] Corresponding adjustments are also made in step S5 of the preparation method.

[0183] Comparative example B3

[0184] The comparative example electrophoretic particles differ from example B1 only in that the material of the core is the particles provided in comparative example A3.

[0185] Corresponding adjustments are also made in step S5 of the preparation method.

[0186] Comparative example B4

[0187] The comparative example electrophoretic particles differ from example B1 only in that the material of the core is the particles provided in comparative example A4.

[0188] Corresponding adjustments are also made in step S5 of the preparation method.

[0189] Related performance tests and result analysis

[0190] 1. The black particles provided in examples A1 to A9 and the black electrophoretic particles of examples B1 to B9 were respectively subjected to scanning electron microscope analysis, wherein the electron microscope image of the black particles in example A1 is shown in Figure 3 , and the electron microscope images of the black particles provided in the other examples are similar to the electron microscope image of the black particles in example A1; the electron microscope image of the black electrophoretic particles in example B1 is shown in Figure 4 , and the electron microscope images of the black electrophoretic particles provided in the other examples are similar to the electron microscope image of the black electrophoretic particles in example B1.

[0191] From Figure 3 and Figure 4 It can be seen that, Figure 3 the black particles in the box in Figure 4 have the phenomenon of accumulation and agglomeration, and the modified black electrophoretic particles in have improved dispersibility and are not prone to accumulation and agglomeration, so that in the application of electrophoretic display, the black particles can be modified by organic coating to obtain black electrophoretic particles, so as to improve the electrophoretic display effect.

[0192] 2. The related data of the black electrophoretic particles provided in examples B1 to B9 and the black electrophoretic particles provided in comparative examples B1 to B4 are shown in Table 1.

[0193] Table 1

[0194]

[0195] The black electrophoretic particles were made into electrophoretic display fluids respectively, and the white electrophoretic particles, dispersing agent, stabilizer, charge control agent were ensured to be the same. The related performances were tested respectively: the response time of the electrophoretic display device was tested by the electronic ink tester. First, the electrophoretic display prototype device needs to be prepared, and the specific process is as follows: first, the instrument is calibrated with a standard white board, then the power supply poles of the tester are connected with the two end electrodes of the display device, the display device is placed horizontally on the sample table, and the integrating sphere is adjusted. Then the output waveform is designed by the waveform design program, the display effect of the device under the driving electric field in a cycle is collected by the photoelectric test system, the response curve is obtained, four points are collected on the curve according to the point selection principle, and the response time is calculated by the test software. The Lab color space is established by the International Commission on Illumination (CIE) in 1976, the L* axis represents the lightness, the black is at the bottom end, and the white is at the top end. L* represents the reflected light intensity, and the higher the L*, the higher the reflectivity. For the black and white particle electrophoretic display, the higher the L* value, the better the whiteness in the white state, and the lower the L*, the better the blackness in the black state. Reflectivity R = ((L*+16) / 116) ^ 3*100, and the contrast ratio = Rwhite / Rblack. The above results are shown in Table 2.

[0196] Table 2

[0197]

[0198] According to the component relationship in Table 1 and the test results in Table 2, compared with Comparative Examples B1-B4, the dispersion stability of the black electrophoretic particles obtained by modifying the manganese-iron black with organic coating in the organic dispersing agent is good, the absolute value of the Zeta potential is higher (positive or negative), the system is stable, the particle deposition is reduced, the surface charge is significantly improved, the response speed under the electric field is significantly improved, the black and white contrast ratio is obviously improved, and thus the electrophoretic display effect is good.

[0199] The above only describes the preferred embodiments of the present application and should not be used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A black electrophoretic particle, characterized in that, The black electrophoretic particles comprise a core and a shell covering the core. The core comprises black particles, which are a mixed-phase component of manganese dioxide, iron tetroxide, and copper oxide, excluding chromium oxide. The mass percentages of manganese dioxide, iron tetroxide, and copper oxide in the mixed-phase component, based on 100% of the total mass of the black particles, are as follows: The manganese dioxide content is 1.0% to 80%. The iron(III) oxide content is 10%–90%. The copper oxide content is 0.1% to 80%. The shell material comprises a polymer; the polymer is grafted onto the core surface by a coupling agent; the grafting rate between the core surface and the polymer is 10% to 30%. The polymer is polymerized from at least one of the following polymer monomers: methyl methacrylate, butyl methacrylate, isooctyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, acrylamide, methyl acrylate, styrene, and divinylbenzene.

2. The black electrophoretic particles according to claim 1, characterized in that, The specific surface area of ​​the black particles is 15m². 2 / g~25m 2 / g.

3. The black electrophoretic particles according to claim 1, characterized in that, The black particles have a particle size of 0.5 μm to 1.8 μm.

4. The black electrophoretic particles according to claim 1, characterized in that, The density of the black particles is 4.5 g / cm³. 3 ~5.5g / cm 3 .

5. The black electrophoretic particles according to claim 1, characterized in that, The black particles have a light absorption rate of ≥80%.

6. The black electrophoretic particles according to claim 1, characterized in that: Based on 100% of the total mass of the black particles, it also includes the following miscible components by mass percentage: Zinc oxide 0.1%–1.0%.

7. The black electrophoretic particles according to claim 1, characterized in that, The method for preparing the black particles includes the following steps: After a first mixing treatment of manganese source, iron source and copper source, a first sintering treatment is performed to obtain a first sintered product. The first sintered product is ground to obtain a ground product; The grinding product is granulated and then subjected to a second sintering process to obtain a second sintered product. The second sintered product was pulverized to obtain black particles; The manganese source, iron source, and copper source are mixed in the first mixing process according to a mass ratio of 1-80:10-90:0.1-80 for manganese dioxide, iron tetroxide, and copper oxide contained in the black particles.

8. The black electrophoretic particles according to claim 7, characterized in that, The manganese source includes at least one of manganese dioxide, manganese carbonate, manganese nitrate, manganese sulfate, and manganese chloride; and / or The iron source includes at least one of magnetite, ferrous sulfate, ferric nitrate, and ferric chloride; and / or The copper source includes at least one of copper oxide, copper nitrate, basic copper carbonate, and copper hydroxide; and / or The first mixing process also includes the addition of a zinc source.

9. The black electrophoretic particles according to claim 7 or 8, characterized in that, The manganese source is manganese dioxide, the iron source is iron(III) oxide, and the copper source is copper oxide.

10. The black electrophoretic particles according to claim 1, characterized in that, The zeta potential of the black electrophoretic particles is 30mV to 55mV.

11. A method for preparing black electrophoretic particles as described in any one of claims 1 to 10, comprising the following steps: Provide the black particles; The black particles are mixed with the polymer monomer in a second process and then subjected to a polymerization reaction to obtain black electrophoretic particles.

12. The preparation method according to claim 11, characterized in that, The mass ratio of the polymer monomer to the black particles is 0.5 to 3:1; and / or An initiator is also added to the mixture in the second mixing treatment; and / or The polymerization reaction is performed at a temperature of 80°C to 140°C; and / or The polymer monomer is mixed with the black particles in the second mixing treatment in the form of a polymer monomer solution, wherein the concentration of the polymer monomer solution is 0.5–5.0 g / mL; and / or Before the second mixing treatment of the black particles with the polymer monomer, the method further includes a step of surface modification treatment of the black particles.

13. The preparation method according to claim 12, characterized in that, The surface modification treatment includes a third mixing treatment of the silane coupling agent with the black particles; and / or The surface modification treatment temperature is 70℃~110℃.

14. The preparation method according to claim 13, characterized in that, The silane coupling agent comprises at least one of 3-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-aminoethylaminopropyltrimethoxysilane, and vinylbenzylaminoethylaminopropyltrimethoxysilane hydrochloride; and / or The mass ratio of the black particles to the silane coupling agent is 0.2–5:1; and / or The initiator includes at least one of azo chain initiators, organic peroxide initiators, and oil-soluble redox chain initiators; and / or The mass ratio of the initiator to the polymer monomer is 0.005 to 0.05:

1.

15. The application of the black electrophoretic particles according to any one of claims 1 to 10 in electrophoretic display.

16. An electronic paper comprising black electrophoretic particles, characterized in that, The black electrophoretic particles include the black electrophoretic particles according to any one of claims 1 to 10, or the black electrophoretic particles prepared by the preparation method according to any one of claims 11 to 14.

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