Mixed black electrophoretic particles, methods of making and using the same

Abstract

The application relates to the technical field of electrophoretic display, in particular to mixed black electrophoretic particles and a preparation method and application thereof. The application provides mixed black electrophoretic particles, which comprise modified first black electrophoretic particles and modified second black electrophoretic particles; the density of the modified first black electrophoretic particles is 0.60-1.38 kg / L; the density of the modified second black electrophoretic particles is 1.40-5.04 kg / L; and the specific surface area of the modified second black electrophoretic particles is >15 m 2 / g. The mixed black electrophoretic particles have the excellent properties of fast response speed and high contrast, and are beneficial to wide application.

Description

TECHNICAL FIELD

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

[0002] Electronic paper is a display device that controls the change of pictures by using the electrophoresis effect of particles, which is commonly used in electronic price tags, electronic book readers and other daily life. The electrophoretic particle is the core of the electronic paper display technology. In the current electronic paper display, the black electrophoretic particle generally uses a single black particle, which cannot balance the response speed and contrast ratio, and affects the use experience of the electronic paper. SUMMARY

[0003] The present application provides a mixed black electrophoretic particle and a preparation method and application thereof, aiming to solve the problem that the black electrophoretic particle in the electrophoretic display liquid provided by the prior art only uses a single electrophoretic particle, and cannot have both fast response speed and good contrast ratio.

[0004] To achieve this purpose, the technical scheme adopted by the present application is as follows:

[0005] In a first aspect, the present application provides a mixed black electrophoretic particle, which comprises modified first black electrophoretic particles and modified second black electrophoretic particles. The density of the modified first black electrophoretic particles is 0.60-1.38 kg / L, the density of the modified second black electrophoretic particles is 1.40-5.04 kg / L, and the specific surface area of the modified second black electrophoretic particles is >15 m 2 / g.

[0006] In some embodiments, the density of the modified first black electrophoretic particles differs from the density of the dispersion medium of the electrophoretic liquid by 0%-100%.

[0007] In some embodiments, the density of the modified first black electrophoretic particles differs from the density of the dispersion medium of the electrophoretic liquid by 0%-50%.

[0008] In some embodiments, the modified first black electrophoretic particles are first black electrophoretic particles with polymers connected to the surface, and the density of the obtained modified first black electrophoretic particles is 0.60-1.38 kg / L.

[0009] In some embodiments, the modified second black electrophoretic particles are second black electrophoretic particles with polymers connected to the surface, and the density of the obtained modified second black electrophoretic particles is 1.40-5.04 kg / L, and the specific surface area of the modified second black electrophoretic particles is >15 m 2 / g.

[0010] In some embodiments, the polymer includes at least one of polyethylene, polypropylene, polyacrylate, polyurethane, polyester, polysiloxane.

[0011] In some embodiments, the first black electrophoretic particle includes at least one of copper chromium black, pigment black 32, antimony sulfide, carbon black, manganese iron black, iron oxide black, iron chromium black, cobalt black.

[0012] In some embodiments, the second black electrophoretic particle includes at least one of copper chromium black, pigment black 32, antimony sulfide, carbon black, manganese iron black, iron oxide black, iron chromium black, cobalt black.

[0013] In some embodiments, the mass ratio of the modified first black electrophoretic particle and the modified second black electrophoretic particle is 1:0.01-1.

[0014] In some embodiments, the particle size of the modified first black electrophoretic particle is 180-240 nm.

[0015] In some embodiments, the particle size of the modified second black electrophoretic particle is 180-240 nm.

[0016] In a second aspect, the present application provides a preparation method of mixed black electrophoretic particles, including the following steps:

[0017] At least two black electrophoretic particles are provided;

[0018] The black electrophoretic particles, silane coupling agent, polymer monomer and solvent are mixed to carry out modification reaction respectively, and the polymer is grafted on the surface of the black electrophoretic particles through the silane coupling agent to obtain the modified first black electrophoretic particle and the modified second black electrophoretic particle, wherein the density of the modified first black electrophoretic particle is 0.60-1.38 kg / L, the density of the modified second black electrophoretic particle is 1.40-5.04 kg / L, and the specific surface area of the modified second black electrophoretic particle is >15 m 2 / g.

[0019] In some embodiments, the silane coupling agent is at least one selected from a silane containing a methacryloyloxy group and a double bond, and a silane containing an aminoalkyl group and a double bond group.

[0020] In some embodiments, the polymer monomer is at least one selected from lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hexyl acrylate, hexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, n-octadecyl acrylate, n-octadecyl methacrylate.

[0021] In some embodiments, the solvent is at least one selected from ethanol, benzene, toluene and xylene.

[0022] In some embodiments, the mass ratio of the black electrophoretic particles, the silane coupling agent, the polymer monomer, the solvent is 1:0.1-0.3:0.8-2:1-8.

[0023] In a third aspect, the present application provides a black-and-white electrophoretic display liquid, which comprises the following components in the following weight percentages, based on the total mass of the black-and-white electrophoretic display liquid:

[0024]

[0025] The electrophoretic particles comprise mixed black electrophoretic particles and modified white electrophoretic particles in a mass ratio of 1:1-10, wherein the mixed black electrophoretic particles are the mixed black electrophoretic particles described above or are prepared by the preparation method of the mixed black electrophoretic particles described above.

[0026] In a fourth aspect, the present application provides an electrophoretic display device, which comprises a substrate and an electrophoretic display layer laminated on any one side of the substrate, wherein the electrophoretic display layer is obtained by coating and drying the black-and-white electrophoretic display liquid described above.

[0027] The mixed black electrophoretic particles provided in the first aspect of the present application comprise modified first black electrophoretic particles with relatively small density and modified second black electrophoretic particles with relatively large density and large specific surface area, which are not easy or cannot be increased to the ideal degree by physical or chemical means. The modified first black electrophoretic particles with relatively small density can improve the electrophoretic speed and response speed. Further, the modified second black electrophoretic particles with relatively large density and large specific surface area are used in combination. The modified second black electrophoretic particles can improve the black value of the mixed black electrophoretic particles as a whole and improve the contrast of the mixed black electrophoretic particles in the electrophoretic system. Therefore, the mixed black electrophoretic particles obtained have excellent properties of fast response speed and high contrast, which are beneficial to wide application.

[0028] The preparation method of the mixed black electrophoretic particles provided in the second aspect of the present application is simple, convenient, and mild in reaction conditions, which is beneficial to industrial application.

[0029] The third aspect of the present application provides a black-and-white electrophoretic display liquid, which comprises electrophoretic particles, a charge control agent, a stabilizer, and a dispersion medium, wherein the electrophoretic particles comprise the mixed black electrophoretic particles described above. The mixed black electrophoretic particles have excellent properties of fast response speed and high contrast, and therefore the black-and-white electrophoretic display liquid obtained has fast response under an electric field and good coloring effect.

[0030] The electrophoretic display device provided by the fourth aspect of the present application has a corresponding fast speed and high contrast effect, and is convenient to prepare and has a high success rate. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. 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 effort on the basis of these drawings.

[0032] Figure 1 is a schematic diagram of the electrophoretic display liquid provided by the embodiments of the present application under the action of voltage to produce electrophoresis phenomenon.

[0033] Figure 2 is a schematic diagram of the liquid crystal box provided by the embodiments of the present application. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly, the present application will be further described in detail in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0035] In the present application, the term "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural. The character " / " generally represents that the associated objects before and after it are in an "or" relationship.

[0036] In the present application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or similar expressions means any combination of these items, including any combination of single item or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple.

[0037] It should be understood that the magnitude of the serial number of the above processes does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of the processes should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0038] The terms used in the embodiments of the present application are merely for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0039] The weight of the related components mentioned in the specification of the embodiments of the present application can not only refer to the specific content of each component, but also represent the weight ratio relationship between each component, therefore, as long as the content of the related components in the specification of the embodiments of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the specification of the embodiments of the present application. Specifically, the mass in the specification of the embodiments of the present application can be μg, mg, g, kg and other mass units commonly known in the chemical field.

[0040] The terms "first", "second" are only for the purpose of description, 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 the indicated technical features. For example, without departing from the scope of the embodiments 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 limited by "first", "second" can explicitly or implicitly include one or more of the features.

[0041] As known by those skilled in the art, the core technology of electronic paper display is electrophoretic image display, which uses colloidal dispersed particles to move directionally and controllably under the action of electric field, so as to realize the purpose of displaying specified content. At present, the double-color black and white electrophoretic fluid is composed of positively charged black electrophoretic particles, negatively charged white particles and dispersion medium. In the prior art, the black electrophoretic particles are usually particles such as iron manganese black or copper chromium black obtained by modification, and one of the particles is selected as the black electrophoretic particle when the electrophoretic fluid is configured. It can also be understood that, in order to obtain excellent display effect, the electrophoretic particles generally should have the following characteristics: 1) should have good optical properties, so as to meet very high refractive index, scattering coefficient and very low absorption coefficient; 2) should maintain the bistable state characteristics, and the density of the electrophoretic particles should be close to the density of the dispersion medium, so as to reduce and decrease the aggregation of the particles; 3) the particle size of the particles should be within a reasonable range, and have controllable optical properties and aggregation state; 4) the particles should not be soluble in organic solvents, and should have good chemical stability in solvents; 5) the surface properties of the particles are controllable, easy to modify, and improve the charge adsorption capacity.

[0042] And the currently used single black particles are greatly affected by the properties of raw materials, for example, the density of iron-manganese black particles is relatively large, and the density of the modified particles is greatly different from that of the dispersion medium, thus leading to a slow electrophoretic speed in electrophoretic display, affecting the response time of electronic paper; and the copper-chromium black has a low black value in the process of electrophoretic display due to its optical properties, showing gray color, resulting in poor contrast; in addition, carbon black is prone to agglomeration in the electrophoretic fluid due to its large specific surface area.

[0043] It can be found that the existing black and white electrophoretic display fluid mainly uses single modified black particles for configuration, and the obtained electrophoretic display fluid cannot simultaneously have fast response speed and good contrast.

[0044] Therefore, the first aspect of the embodiments of the present application provides a mixed black electrophoretic particle, which comprises modified first black electrophoretic particles and modified second black electrophoretic particles, the density of the modified first black electrophoretic particles is 0.60-1.38 kg / L, the density of the modified second black electrophoretic particles is 1.40-5.04 kg / L, and the specific surface area of the modified second black electrophoretic particles is >15 m 2 / g.

[0045] The mixed black electrophoretic particle provided by the first aspect of the embodiments of the present application comprises modified first black electrophoretic particles with relatively small density but not easy or unable to increase the specific surface area to the ideal degree by physical or chemical means, and modified second black electrophoretic particles with relatively large density and specific surface area. The modified first black electrophoretic particles with relatively small density can improve the electrophoretic speed of the electrophoretic particles and improve the response speed. Further, the modified second black electrophoretic particles with relatively large density and specific surface area are used together. The modified second black electrophoretic particles can improve the black value of the mixed black electrophoretic particles as a whole and improve the contrast of the mixed black electrophoretic particles in the electrophoretic system. Therefore, the obtained mixed black electrophoretic particles have excellent properties of fast response speed and high contrast, which are beneficial to wide application.

[0046] In the mixed black electrophoretic particle, the density of the modified first black electrophoretic particles is 0.60-1.38 kg / L. The density of the modified first black electrophoretic particles is small, in order to better improve the electrophoretic speed of the electrophoretic particles, so as to improve the response speed. In some embodiments, the density of the modified first black electrophoretic particles includes but is not limited to 0.6 kg / L, 0.75 kg / L, 0.85 kg / L, 0.97 kg / L, 1.07 kg / L, 1.12 kg / L, 1.20 kg / L; not limited to the listed values, other values not listed in the value range are also applicable.

[0047] In some embodiments, the density of the modified first black electrophoretic particle differs from the density of the dispersion medium of the electrophoretic fluid by 0% to 100%. Controlling the density of the modified first black electrophoretic particle to be close to the density of the dispersion medium of the electrophoretic fluid can increase the electrophoretic velocity of the modified first black electrophoretic particle, increase the response speed, and shorten the response time.

[0048] In some embodiments, the density of the modified first black electrophoretic particle differs from the density of the dispersion medium of the electrophoretic fluid by 0% to 50%. When the density of the modified first black electrophoretic particle and the density of the dispersion medium of the electrophoretic fluid are closer, the electrophoretic velocity of the modified first black electrophoretic particle is higher, the corresponding speed is higher, and the response time is shorter. The specific surface area refers to the area possessed by a unit mass of material, for example, 10 particles in 1 g of particles, which is the surface area of the ten particles, and if there is only 1 particle in 1 g of particles, it is the surface area of the particle. Since the specific surface area is an inherent property of the raw material of the particle, subsequent modification cannot easily change this parameter. The modified first black electrophoretic particle is a particle whose specific surface area cannot be increased to the desired level by physical or chemical means, so the specific surface area of the modified first black electrophoretic particle is not required, but a modified second black electrophoretic particle is compounded. The purpose of adding the modified second black electrophoretic particle is to compensate for the first modified electrophoretic particle, which has a smaller density but a larger specific surface area and cannot be increased to the desired level by physical or chemical means. In the mixed black electrophoretic particles, the density of the modified second black electrophoretic particle is 1.40 to 5.04 kg / L, and the specific surface area of the modified second black electrophoretic particle is > 15 m 2 / g. Since black particles achieve the purpose of displaying black by absorbing light sources, the larger the specific surface area, the more uneven the particle surface, the more gaps there are, and the less light is reflected. The more light is captured by the black particles and cannot be reflected out. However, the larger the specific surface area of the particle, the higher the surface energy of the particle, which makes it easy to accumulate and agglomerate, and it is not easy to modify to the desired density by chemical or physical means. Therefore, the provided modified second black electrophoretic particle is a black particle with a larger density and a larger specific surface area, which can compensate for the black value of the modified first black electrophoretic particle and improve the contrast.

[0049] In some embodiments, the modified first black electrophoretic particle is a black electrophoretic particle having a polymer connected to the surface, and the density of the obtained modified first black electrophoretic particle is 0.60 to 1.38 kg / L. By modifying the first black electrophoretic particle with a polymer, the density of the obtained modified first black electrophoretic particle is 0.60 to 1.38 kg / L.

[0050] In some embodiments, the first black electrophoretic particle includes at least one of copper chromium black, pigment black 32, antimony sulfide, carbon black, manganese iron black, iron oxide black, iron chromium black, and cobalt black.

[0051] In some embodiments, the modified second black electrophoretic particles are black electrophoretic particles with polymers attached to the surface. The density of the modified second black electrophoretic particles is 1.40-5.04 kg / L, and the specific surface area of the modified second black electrophoretic particles is >15 m 2 / g.

[0052] In some embodiments, the second black electrophoretic particles include at least one of copper chromium black, pigment black 32, antimony sulfide, carbon black, manganese iron black, iron oxide black, iron chromium black, and cobalt black.

[0053] In some embodiments, the polymers include at least one of polyethylene, polypropylene, polyacrylate, polyurethane, polyester, and polysiloxane.

[0054] In the detailed description, the first black electrophoretic particles and the second black electrophoretic particles can be modified by the same kind of black electrophoretic particles or different kinds of black electrophoretic particles. In the modification of the first black electrophoretic particles or the second black electrophoretic particles, the same kind or different kinds of polymers can be used. Specifically, the appropriate polymers are selected according to the specifications and performance descriptions provided by the manufacturers of the black particles to ensure that the density of the modified first black electrophoretic particles is 0.60-1.38 kg / L, and the density of the modified second black electrophoretic particles is 1.40-5.04 kg / L, and the specific surface area of the modified second black electrophoretic particles is >15 m 2 / g.

[0055] In some embodiments, the mass ratio of the modified first black electrophoretic particles to the modified second black electrophoretic particles is 1:0.01-1. Compared with the modified second black electrophoretic particles, the modified first black electrophoretic particles have a smaller specific surface area and a weaker ability to capture light, which can cause the particles to appear gray and result in a low contrast ratio. Therefore, if the amount of the modified first black electrophoretic particles is too small, the mixed black electrophoretic particles can improve the contrast ratio, but the response time will be significantly slower. If the amount of the modified first black electrophoretic particles is too large, the mixed black electrophoretic particles will have a fast response speed but a poor contrast ratio, which is not easy to distinguish.

[0056] In some embodiments, the mass ratio of the modified first black electrophoretic particles and the modified second black electrophoretic particles includes, but is not limited to, 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, or 1:1; not limited to the listed values, other values not listed in the value range are also applicable.

[0057] In some embodiments, the particle size of the modified first black electrophoretic particles is 180-240 nm. In some embodiments, the particle size of the modified first black electrophoretic particles includes, but is not limited to, 180 nm, 185 nm, 190 nm, 195 nm, 200 nm, 205 nm, 210 nm, 215 nm, 220 nm, 225 nm, 230 nm, 235 nm, 240 nm, and the like typical but non-limiting values, other values not listed in the value range are also applicable.

[0058] In some embodiments, the particle size of the modified second black electrophoretic particles is 180-240 nm. In some embodiments, the particle size of the modified second black electrophoretic particles includes, but is not limited to, 180 nm, 185 nm, 190 nm, 195 nm, 200 nm, 205 nm, 210 nm, 215 nm, 220 nm, 225 nm, 230 nm, 235 nm, 240 nm, and the like typical but non-limiting values, other values not listed in the value range are also applicable.

[0059] In some embodiments, the particle size of the modified first black electrophoretic particles and the modified second black electrophoretic particles is consistent.

[0060] In some embodiments, the provided mixed black electrophoretic particles can also include at least one black electrophoretic particle of a modified third black electrophoretic particle, a modified fourth black electrophoretic particle, a modified fifth black electrophoretic particle, and the like. It is only necessary to ensure that the obtained mixed black electrophoretic particles include two types of modified black electrophoretic particles, wherein the density of the type one black electrophoretic particles is 0.60-1.38 kg / L, the density of the type two black electrophoretic particles is 1.40-5.04 kg / L, and the specific surface area of the type two black electrophoretic particles is >15 m 2 / g.

[0061] In a second aspect, the application provides a preparation method of mixed black electrophoretic particles, including the following steps:

[0062] S01. At least providing two black electrophoretic particles;

[0063] S02. mixing the black electrophoretic particles, silane coupling agent, polymer monomer and solvent, respectively performing modification reaction, grafting the polymer on the surface of the black electrophoretic particles through the silane coupling agent to obtain modified first black electrophoretic particles and modified second black electrophoretic particles, wherein the density of the modified first black electrophoretic particles is 0.60-1.38 kg / L, the density of the modified second black electrophoretic particles is 1.40-5.04 kg / L, and the specific surface area of the modified second black electrophoretic particles is >15 m 2 / g.

[0064] The preparation method of the mixed black electrophoretic particles provided in the second aspect of the embodiments of the present application is simple, convenient, and has mild reaction conditions, which is conducive to industrial application. In the reaction solution, the silane coupling agent can bridge the polymer and the particles, and the polymer does not directly react with the particles, so that the electrophoretic particles can be prepared by one-pot method, the step of modifying the silane coupling agent and then modifying the polymer is saved, and a long-time vacuum drying process is not required, thereby saving the preparation time and cost.

[0065] In step S01, at least two kinds of black electrophoretic particles are provided.

[0066] In some embodiments, the black electrophoretic particles include at least one of copper chromium black, pigment black 32, antimony sulfide, carbon black, manganese iron black, iron oxide black, iron chromium black, and cobalt black. The selection of particles is important, and the specific particles need to be selected for use according to the specific surface area of the particles provided by the supplier. Because different material manufacturing methods can cause the same particles to have different specific surface areas. Therefore, the specific particles need to be selected for use according to the material specification provided by the supplier.

[0067] In the specific embodiments, based on the characteristics that the density of the modified first black electrophoretic particles is 0.60-1.38 kg / L, the density of the modified second black electrophoretic particles is 1.40-5.04 kg / L, and the specific surface area is >15 m 2 / g, it can be determined that the density and specific surface area of the modified first black electrophoretic particles are smaller than those of the modified second black electrophoretic particles. Therefore, the density and specific surface area of the black electrophoretic particle raw materials selected for preparing the modified first black electrophoretic particles are smaller than those of the black electrophoretic particle raw materials selected for preparing the modified second black electrophoretic particles. In actual operation, the specific material specification of the black electrophoretic particles can be compared one by one to select for use.

[0068] In the modification process, the two kinds of black particles can be modified separately, or the two kinds of black particles can be modified together.

[0069] In step S02, the black electrophoretic particles and the silane coupling agent, the polymer monomer, and the solvent are mixed, and a modification reaction is performed, respectively, to graft the polymer to the surface of the black electrophoretic particles through the silane coupling agent, to obtain modified first black electrophoretic particles and modified second black electrophoretic particles, wherein the density of the modified first black electrophoretic particles is 0.60-1.38 kg / L, the density of the modified second black electrophoretic particles is 1.40-5.04 kg / L, and the specific surface area of the modified second black electrophoretic particles is >15 m 2 / g.

[0070] In some embodiments, the silane coupling agent is selected from at least one of a silane comprising a methacryloxy group and a double bond, a silane comprising an aminoalkyl group and a double bond group.

[0071] In one embodiment, the silane comprising a methacryloxy group includes, but is not limited to, at least one of methacryloxypropyltrimethoxysilane (e.g., KH-570), methacryloxypropylmethyldimethoxysilane (e.g., KH-571), methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldiethoxysilane.

[0072] In one embodiment, the silane comprising an aminoalkyl group is, for example, but not limited to, at least one of diethylenetriaminopropyltrimethoxysilane, vinylbenzylaminoethylaminopropyltrimethoxysilane, N-[3-(trimethoxysilyl)propyl]-N'-4-(vinylbenzyl)ethylenediamine hydrochloride.

[0073] In some embodiments, the polymer monomer is selected from at least one of lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hexyl acrylate, hexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, n-octadecyl acrylate, n-octadecyl methacrylate.

[0074] After the reaction, the polymer connected to the surface of the electrophoretic particles includes, but is not limited to, at least one of polyethylene, polypropylene, polyacrylate, polyurethane, polyester, polysiloxane. The polymer has bistability for the electrophoretic display, and more preferably a polymer with more side chains or longer length as a stabilizer.

[0075] In some embodiments, the solvent is selected from at least one of ethanol, benzene, toluene, and xylene.

[0076] In some embodiments, the mass ratio of the black electrophoretic particles, the silane coupling agent, the polymer monomer, and the solvent is 1:0.1-0.3:0.8-2:1-8. If the ratio of the electrophoretic particles, the solvent, the silane coupling agent, and the polymer monomer is not appropriate, the electrophoretic particles have poor charging and dispersing properties, which affects the electrophoretic effect of the electrophoretic particles in the electrophoretic fluid. In some preferred embodiments, the mass ratio of the black electrophoretic particles, the silane coupling agent, the polymer monomer, and the solvent is 1:0.1-0.2:1-1.5:1-3.

[0077] In some specific embodiments, the mass ratio of the black electrophoretic particles, the silane coupling agent, the polymer monomer, and the solvent includes, but is not limited to, any one of 1:0.1:0.8:1, 1:0.2:1:3, 1:0.25:1.5:5, and 1:0.3:2:8; but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0078] Finally, the modified first black electrophoretic particles and the modified second black electrophoretic particles are obtained, wherein the density of the modified first black electrophoretic particles is 0.60-1.38 kg / L, the density of the modified second black electrophoretic particles is 1.40-5.04 kg / L, and the specific surface area of the modified second black electrophoretic particles is >15 m 2 / g.

[0079] The third aspect of the embodiments of the present application provides a black-and-white electrophoretic display fluid (such as Figure 1 ), with the total mass of the black-and-white electrophoretic display fluid being 100%, which includes the following components in the following weight percentages:

[0080] electrophoretic particles 10%-50%,

[0081] charge control agent 2%-15%,

[0082] stabilizer 0.1%-1%,

[0083] dispersion medium 46%-87.9%;

[0084] The electrophoretic particles include mixed black electrophoretic particles and modified white electrophoretic particles in a mass ratio of 1:1-10, and the mixed black electrophoretic particles are the mixed black electrophoretic particles described above or are prepared by the preparation method of the mixed black electrophoretic particles described above.

[0085] The third aspect of the embodiments of the present application provides a black-and-white electrophoretic display fluid, which includes electrophoretic particles, a charge control agent, a stabilizer, and a dispersion medium. The electrophoretic particles include the mixed black electrophoretic particles described above. The mixed black electrophoretic particles have excellent properties of fast response speed and high contrast ratio, so that the obtained black-and-white electrophoretic display fluid has fast response speed and good coloring effect under an electric field.

[0086] In some embodiments, the total mass of the black-and-white electrophoretic display fluid is 100%, including 10% to 50% by weight of the electrophoretic particles. In some embodiments, the total mass of the black-and-white electrophoretic display fluid is 100%, including, but not limited to, 10%, 15%, 20%, 25%, 30%, 35%, 45%, 50% by weight of the electrophoretic particles; not limited to the listed values, other values not listed in the range of values are also applicable.

[0087] In some embodiments, the electrophoretic particles include mixed black electrophoretic particles and modified white electrophoretic particles, and the mixed black electrophoretic particles are the mixed black electrophoretic particles described above.

[0088] In some embodiments, the mass ratio of the mixed black electrophoretic particles to the modified white electrophoretic particles is 1:1 to 10. If the mass ratio of the mixed black electrophoretic particles to the modified white electrophoretic particles is not appropriate, the covering power between the mixed black electrophoretic particles and the modified white electrophoretic particles is weak, and the difference between the positive and negative charges is large, which affects the optical performance of the device. In some preferred embodiments, the mass ratio of the mixed black electrophoretic particles to the modified white electrophoretic particles is 1:2 to 6.

[0089] In some specific embodiments, the mass ratio of the mixed black electrophoretic particles to the modified white electrophoretic particles includes, but is not limited to, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10; but not limited to the listed values, other values not listed in the range of values are also applicable.

[0090] In some embodiments, the modified white electrophoretic particles are selected from titanium dioxide. In some embodiments, the particle size of the titanium dioxide is 50 to 200 nm.

[0091] In some embodiments, the total mass of the black-and-white electrophoretic display fluid is 100%, including 2% to 15% by weight of the charge control agent. In some embodiments, the total mass of the black-and-white electrophoretic display fluid is 100%, including, but not limited to, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% by weight of the charge control agent; not limited to the listed values, other values not listed in the range of values are also applicable.

[0092] In some embodiments, the charge control agent is selected from polydodecyl hydroxy stearic acid dispersant. In some specific embodiments, the charge control agent is selected from at least one of Solsperse 3000, Solsperse 8000, Solsperse 13300, Solsperse 17000, and Solsperse 19000.

[0093] The total mass of the black-and-white electrophoretic display fluid is 100%, including 0.1% to 1% by weight of the stabilizer. In some embodiments, the total mass of the black-and-white electrophoretic display fluid is 100%, and the weight percentage of the stabilizer includes but is not limited to 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%; not limited to the listed values, other values not listed in the range are also applicable.

[0094] In some embodiments, the stabilizer is selected from at least one of high molecular resin polyisobutylene, ethylene glycol ester, acetylene glycol, alkyl amine, and alkyl alcohol amide.

[0095] The total mass of the black-and-white electrophoretic display fluid is 100%, including 46% to 87.9% by weight of the dispersion medium.

[0096] In some embodiments, the commonly used dispersion medium can be organic halides and halogen-containing oligomers, such as tetrafluorodibromoethylene, tetrachloroethylene, trifluorochloroethylene, 1,2,4-trichlorobenzene, carbon tetrachloride, polytrifluorochloroethylene (polymerization degree 2-10), perfluoroether, etc.; the dispersion medium can also be silicone oil and straight-chain or branched-chain saturated hydrocarbons, such as octamethylcyclotetrasiloxane, high molecular cyclotetrasiloxane, polymethylphenylsiloxane, hexamethyldisiloxane, dodecane, n-tetradecane, naphtha, Isopar series and Norpar series of ExxonMobil Chemical Company, etc. In the embodiments of the present application, the dispersion medium is preferably selected from the Isopar series of isomeric alkane solvents. The Isopar series of isomeric alkanes has a high boiling point and a low volatility, has a low dielectric constant, a low conductivity, has good optical and chemical stability, has a suitable viscosity, has low toxicity and environmental friendliness. In the Isopar series, there are differences in physical properties such as boiling point, melting point, flash point and viscosity of each reagent.

[0097] In some specific embodiments, the dispersion medium is selected from at least one of Isopar B, Isopar E, Isopar G, Isopar H, Isopar L and Isopar M.

[0098] Further, a preparation method of a black-and-white electrophoretic display fluid is provided, including the following steps:

[0099] G01. Each component of the black-and-white electrophoretic display fluid is provided according to the above,

[0100] G02. The black-and-white electrophoretic display fluid is obtained by uniformly mixing the black electrophoretic particles, the modified white electrophoretic particles, the charge control agent, the stabilizer and the dispersion medium, and then performing a ball milling reaction and separating the ball milling fluid.

[0101] In step G01, the components are provided according to the black-and-white dual-color electrophoretic display fluid described above, and the specific types and amounts are as discussed above, which will not be repeated here for the sake of brevity.

[0102] In step G02, the black electrophoretic particles, the modified white electrophoretic particles, the charge control agent, the stabilizer, and the dispersion medium are mixed uniformly, and then subjected to a ball milling reaction, and the ball milling liquid is separated to obtain the black-and-white dual-color electrophoretic display fluid.

[0103] In some embodiments, the method for preparing the modified white electrophoretic particles includes the following steps:

[0104] The white electrophoretic particles are provided, and the white electrophoretic particles, the silane coupling agent, the polymer monomer, and the solvent are mixed to perform a modification reaction, so that the polymer is grafted on the surface of the white electrophoretic particles through the silane coupling agent.

[0105] In some embodiments, the mass ratio of the white electrophoretic particles, the silane coupling agent, the polymer monomer, and the solvent is 1:0.1-0.3:0.8-2:1-8. If the ratio of the electrophoretic particles to the solvent, the silane coupling agent, and the polymer monomer is not appropriate, the electrophoretic particles have poor charging properties and dispersibility, which affects the electrophoretic effect in the electrophoretic fluid. In some preferred embodiments, the mass ratio of the white electrophoretic particles, the silane coupling agent, the polymer monomer, and the solvent is 1:0.1-0.2:1-1.5:1-3.

[0106] In some specific embodiments, the mass ratio of the white electrophoretic particles, the silane coupling agent, the polymer monomer, and the solvent includes, but is not limited to, any one of 1:0.1:0.8:1, 1:0.2:1:3, 1:0.25:1.5:5, and 1:0.3:2:8; but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0107] In the step of modifying the black electrophoretic particles and the white electrophoretic particles, the types of the silane coupling agent, the polymer monomer, and the solvent are the same; and for the sake of brevity, the details will not be repeated here. The fourth aspect of the embodiments of the present application provides an electrophoretic display device, which includes a substrate and an electrophoretic display layer stacked on any one side of the substrate, wherein the electrophoretic display layer is obtained by coating and drying the black-and-white dual-color electrophoretic display fluid described above.

[0108] The electrophoretic display device provided by the fourth aspect of the embodiments of the present application has the characteristics of fast response and high contrast, and the preparation process is simple. Therefore, the electrophoretic display layer of the electrophoretic display device obtained by coating and drying the black-and-white dual-color electrophoretic display fluid has the effects of fast response and high contrast, and is easy to prepare and has a high success rate.

[0109] The following will be described in conjunction with specific examples.

[0110] The liquid crystal cell used in the following examples (as shown in Figure 2 The liquid crystal cell used in the following examples (as shown in

[0111] Example A1

[0112] Mixed black electrophoretic particles

[0113] The mixed black electrophoretic particles include 1 g of modified first black electrophoretic particles and 1 g of modified second black electrophoretic particles, wherein the modified first black electrophoretic particles are modified copper-chromium black particles, the density of the modified first black electrophoretic particles is 0.96 kg / L, the density of the modified first black electrophoretic particles differs from the density of the dispersion medium of the electrophoretic fluid by 20%; the specific surface area of the modified first black electrophoretic particles is 2.7 m 2 / g; and the modified second black electrophoretic particles are modified manganese-iron black particles, the density of the modified second black electrophoretic particles is 3.82 kg / L, and the specific surface area of the modified second black electrophoretic particles is 15.2 m 2 / g.

[0114] The preparation method of the modified first black electrophoretic particles (modified copper-chromium black particles) is as follows: 10 g of copper-chromium black raw material is mixed with 100 mL of toluene solvent, and the mixed solvent and the copper-chromium black raw material are added to a flask. Water and a silane coupling agent are stirred in a beaker for 10 min and then added to the flask, and the dispersion is continued for 30 min. Then, 50 g of methyl methacrylate is added, and the system is stirred at room temperature for 1 h. At this time, the system is a black turbid liquid. Then, the system is heated to 70°C, and an initiator is slowly added dropwise. The reaction is carried out at this temperature overnight. After the incubation is completed, the system is allowed to cool to room temperature, and the grafted copper-chromium black particles are cleaned and vacuum dried for use.

[0115] The preparation method of the modified second black electrophoretic particles (modified manganese-iron black particles) is as follows: 10 g of manganese-iron black raw material is mixed with 100 mL of toluene solvent, and the mixed solvent and the manganese-iron black raw material are added to a flask. Water and a silane coupling agent are stirred in a beaker for 10 min and then added to the flask, and the dispersion is continued for 30 min. Then, 50 g of methyl methacrylate is added, and the system is stirred at room temperature for 1 h. At this time, the system is a black turbid liquid. Then, the system is heated to 70°C, and an initiator is slowly added dropwise. The reaction is carried out at this temperature overnight. After the incubation is completed, the system is allowed to cool to room temperature, and the grafted manganese-iron black particles are cleaned and vacuum dried for use.

[0116] Example A2

[0117] Mixed black electrophoretic particles

[0118] The mixed black electrophoretic particles include 1 g of the modified first black electrophoretic particles and 0.05 g of the modified second black electrophoretic particles, wherein the modified first black electrophoretic particles are modified copper-chromium black particles, the density is 0.96 kg / L, the density of the modified first black electrophoretic particles differs from the density of the dispersion medium of the electrophoretic fluid by 20%; the specific surface area is 2.7 m 2 / g; and the modified second black electrophoretic particles are modified manganese-iron black particles, the density is 3.82 kg / L, and the specific surface area is 15.2 m 2 / g.

[0119] The preparation method of the modified first black electrophoretic particles (modified copper-chromium black particles) is consistent with the preparation method of the modified first black electrophoretic particles (modified copper-chromium black particles) in Example A1.

[0120] The preparation method of the modified second black electrophoretic particles (modified manganese-iron black particles) is consistent with the preparation method of the modified second black electrophoretic particles (modified manganese-iron black particles) in Example A1.

[0121] Example A3

[0122] Mixed black electrophoretic particles

[0123] The mixed black electrophoretic particles include 1 g of the modified first black electrophoretic particles and 0.2 g of the modified second black electrophoretic particles, wherein the modified first black electrophoretic particles are modified copper-chromium black particles, the density is 0.96 kg / L, the density of the modified first black electrophoretic particles differs from the density of the dispersion medium of the electrophoretic fluid by 20%; the specific surface area is 2.7 m 2 / g; and the modified second black electrophoretic particles are modified manganese-iron black particles, the density is 3.82 kg / L, and the specific surface area is 15.2 m 2 / g.

[0124] The preparation method of the modified first black electrophoretic particles (modified copper-chromium black particles) is consistent with the preparation method of the modified first black electrophoretic particles (modified copper-chromium black particles) in Example A1.

[0125] The preparation method of the modified second black electrophoretic particles (modified manganese-iron black particles) is consistent with the preparation method of the modified second black electrophoretic particles (modified manganese-iron black particles) in Example A1.

[0126] Example A4

[0127] Mixed black electrophoretic particles

[0128] The mixed black electrophoretic particles comprise 1 g of modified first black electrophoretic particles and 0.5 g of modified second black electrophoretic particles, wherein the modified first black electrophoretic particles are modified copper-chromium black particles, the density is 0.96 kg / L, the density of the modified first black electrophoretic particles differs from the density of the dispersion medium of the electrophoretic fluid by 20%, the specific surface area is 2.7 m 2 / g; and the modified second black electrophoretic particles are modified manganese-iron black particles, the density is 3.82 kg / L, and the specific surface area is 15.2 m 2 / g.

[0129] The preparation method of the modified first black electrophoretic particles (modified copper-chromium black particles) is consistent with the preparation method of the modified first black electrophoretic particles (modified copper-chromium black particles) in Embodiment A1.

[0130] The preparation method of the modified second black electrophoretic particles (modified manganese-iron black particles) is consistent with the preparation method of the modified second black electrophoretic particles (modified manganese-iron black particles) in Embodiment A1.

[0131] Embodiment A5

[0132] Mixed black electrophoretic particles

[0133] The mixed black electrophoretic particles comprise 1 g of modified first black electrophoretic particles and 0.5 g of modified second black electrophoretic particles, wherein the modified first black electrophoretic particles are modified copper-chromium black particles, the density is 0.96 kg / L, the density of the modified first black electrophoretic particles differs from the density of the dispersion medium of the electrophoretic fluid by 20%, the specific surface area is 2.7 m 2 / g ； The modified second black electrophoretic particles are modified pigment black 32 particles, the density is 1.476 kg / L, and the specific surface area is 39 m 2 / g.

[0134] The preparation method of the modified first black electrophoretic particles (modified copper-chromium black particles) is consistent with the preparation method of the modified first black electrophoretic particles (modified copper-chromium black particles) in Embodiment A1.

[0135] The preparation method of the modified second black electrophoretic particles (modified pigment black 32 particles) is as follows: 10 g of pigment black 32 raw material and 100 mL of toluene solvent are mixed, the solvent and the pigment black 32 raw material are added into a flask, 50 g of styrene is added, and stirring is performed at room temperature for 1 h. At this time, the system is a black turbid liquid. Then, the system is heated to 70°C, and an initiator is slowly added dropwise. The system is incubated at this temperature overnight. After incubation, the system is cooled to room temperature, the grafted pigment black 32 particles are cleaned, and vacuum drying is performed for standby use.

[0136] Embodiment A6

[0137] Mixed black electrophoretic particles

[0138] The mixed black electrophoretic particles comprise 1 g of the modified first black electrophoretic particles and 0.05 g of the modified second black electrophoretic particles, wherein the modified first black electrophoretic particles are modified copper chromium black particles, the density of the modified first black electrophoretic particles is 0.96 kg / L, the density of the modified first black electrophoretic particles differs from the density of the dispersion medium of the electrophoretic fluid by 20%; the specific surface area of the modified first black electrophoretic particles is 2.7 m 2 / g ； The modified second black electrophoretic particles are modified pigment black 32 particles, the density of the modified second black electrophoretic particles is 1.476 kg / L, and the specific surface area of the modified second black electrophoretic particles is 39 m 2 / g.

[0139] The preparation method of the modified first black electrophoretic particles (modified copper chromium black particles) is consistent with the preparation method of the modified first black electrophoretic particles (modified copper chromium black particles) in Embodiment A1.

[0140] The preparation method of the modified second black electrophoretic particles (modified pigment black 32 particles) is consistent with the preparation method of the modified second black electrophoretic particles (modified pigment black 32 particles) in Embodiment A5.

[0141] Embodiment A7

[0142] Mixed black electrophoretic particles

[0143] The mixed black electrophoretic particles comprise 1 g of the modified first black electrophoretic particles and 1 g of the modified second black electrophoretic particles, wherein the modified first black electrophoretic particles are modified copper chromium black particles, the density of the modified first black electrophoretic particles is 0.96 kg / L, the density of the modified first black electrophoretic particles differs from the density of the dispersion medium of the electrophoretic fluid by 20%; the specific surface area of the modified first black electrophoretic particles is 2.7 m 2 / g ； The modified second black electrophoretic particles are modified pigment black 32 particles, the density of the modified second black electrophoretic particles is 1.476 kg / L, and the specific surface area of the modified second black electrophoretic particles is 39 m 2 / g.

[0144] The preparation method of the modified first black electrophoretic particles (modified copper chromium black particles) is consistent with the preparation method of the modified first black electrophoretic particles (modified copper chromium black particles) in Embodiment A1.

[0145] The preparation method of the modified second black electrophoretic particles (modified pigment black 32 particles) is consistent with the preparation method of the modified second black electrophoretic particles (modified pigment black 32 particles) in Embodiment A5.

[0146] Embodiment A8

[0147] Mixed black electrophoretic particles

[0148] The mixed black electrophoretic particles comprise 1 g of modified first black electrophoretic particles and 0.2 g of modified second black electrophoretic particles, wherein the modified first black electrophoretic particles are modified copper-chromium black particles, the density of the modified first black electrophoretic particles is 0.96 kg / L, the density of the modified first black electrophoretic particles differs from the density of the dispersion medium of the electrophoretic fluid by 20%; the specific surface area of the modified first black electrophoretic particles is 2.7 m 2 / g ； The modified second black electrophoretic particles are modified pigment black 32 particles, the density of the modified second black electrophoretic particles is 1.476 kg / L, and the specific surface area of the modified second black electrophoretic particles is 39 m 2 / g.

[0149] The preparation method of the modified first black electrophoretic particles (modified copper-chromium black particles) is consistent with the preparation method of the modified first black electrophoretic particles (modified copper-chromium black particles) in Embodiment A1.

[0150] The preparation method of the modified second black electrophoretic particles (modified pigment black 32 particles) is consistent with the preparation method of the modified second black electrophoretic particles (modified pigment black 32 particles) in Embodiment A5.

[0151] Embodiment A9

[0152] Mixed black electrophoretic particles

[0153] The mixed black electrophoretic particles comprise 5 g of modified first black electrophoretic particles and 5 g of modified second black electrophoretic particles, wherein the modified first black electrophoretic particles are modified carbon black particles, the density of the modified first black electrophoretic particles is 0.94 kg / L, the density of the modified first black electrophoretic particles differs from the density of the dispersion medium of the electrophoretic fluid by 17.5%; the specific surface area of the modified first black electrophoretic particles is 14 m 2 / g; and the modified second black electrophoretic particles are modified manganese-iron black particles, the density of the modified second black electrophoretic particles is 3.82 kg / L, and the specific surface area of the modified second black electrophoretic particles is 15.2 m 2 / g.

[0154] Preparation method: 5 g of manganese-iron black raw material and 5 g of carbon black are taken, 100 mL of toluene solvent is added, the solvent and the black particles are mixed and added to a flask, 50 g of methyl methacrylate and a certain amount of silane coupling agent are added, and stirring is performed at room temperature for 1 h. At this time, the system is a black turbid liquid. Then, the system is heated to 70°C, and the initiator is slowly added dropwise. The system is incubated at this temperature overnight. After incubation, the grafted manganese-iron black particles and carbon black particles are cleaned and vacuum dried for standby use after the system is cooled to room temperature.

[0155] Embodiment A10

[0156] Mixed black electrophoretic particles

[0157] The mixed black electrophoretic particles consist of 10g of modified first black electrophoretic particles and 5g of modified second black electrophoretic particles. The modified first black electrophoretic particles are modified carbon black particles with a density of 0.94 kg / L. The density of the modified first black electrophoretic particles differs from the density of the dispersion medium in the electrophoresis solution by 17.5%. The specific surface area is 14 m². 2 / g; The modified second black electrophoretic particles are modified manganese iron black particles with a density of 3.82 kg / L and a specific surface area of ​​15.2 m². 2 / g.

[0158] Preparation method: Take 10g of manganese iron black raw material and 5g of carbon black, add 150mL of toluene solvent, add the mixed solvent and black particles to a flask, then add 75g of methyl methacrylate and a certain amount of silane coupling agent, stir at room temperature for 1h, at which point the system is a black turbid liquid. Then heat the system to 70℃, slowly add the initiator dropwise, and keep the reaction at this temperature overnight. After the reaction is completed, let the system cool to room temperature, clean the grafted manganese iron black particles and carbon black particles, and vacuum dry them for later use.

[0159] Example A11

[0160] Mixed black electrophoretic particles

[0161] The mixed black electrophoretic particles consist of 10g of modified first black electrophoretic particles and 5g of modified second black electrophoretic particles. The modified first black electrophoretic particles are modified copper chromium black particles with a density of 1.11 kg / L. The density of the modified first black electrophoretic particles differs from the density of the dispersion medium in the electrophoretic solution by 50%. The specific surface area is 14 m². 2 / g; The modified second black electrophoretic particles are modified manganese iron black particles with a density of 3.82 kg / L and a specific surface area of ​​15.2 m². 2 / g.

[0162] Preparation method: Take 10g of manganese iron black raw material and 5g of copper chromium black, add 150mL of toluene solvent, add the mixed solvent and black particles to a flask, then add 75g of methyl methacrylate and a certain amount of silane coupling agent, stir at room temperature for 1h, at which point the system is a black turbid liquid. Then heat the system to 70℃, slowly add the initiator dropwise, and keep the reaction at this temperature overnight. After the reaction is completed, let the system cool to room temperature, clean the grafted manganese iron black particles and carbon black particles, and vacuum dry them for later use.

[0163] Example A12

[0164] Mixed black electrophoretic particles

[0165] The mixed black electrophoretic particles comprise 10 g of modified first black electrophoretic particles and 5 g of modified second black electrophoretic particles, wherein the modified first black electrophoretic particles are modified copper-chromium black particles, the density is 1.33 kg / L, the density of the modified first black electrophoretic particles and the density of the dispersion medium of the electrophoretic fluid differ by 80%; the specific surface area is 14 m 2 / g; and the modified second black electrophoretic particles are modified manganese-iron black particles, the density is 3.82 kg / L, and the specific surface area is 15.2 m 2 / g.

[0166] Preparation method: take 10 g of manganese-iron black raw material and 5 g of copper-chromium black, add 150 mL of toluene solvent, mix the solvent and black particles into a flask, then add 75 g of methyl methacrylate and a certain amount of silane coupling agent, stir at room temperature for 1 h, at this time the system is a black turbid liquid. Then heat the system to 70℃, slowly add the initiator, and keep the temperature at this temperature overnight. After the incubation is completed, the grafted manganese-iron black particles and carbon black particles are washed and dried under vacuum for use.

[0167] Example A13

[0168] Synthesis of modified white electrophoretic particles

[0169] Take 10 g of titanium dioxide raw material and 100 mL of toluene solvent, mix the solvent and titanium dioxide into a flask, stir water and silane coupling agent in a beaker for 10 min, then add them into the flask, continue to disperse for 30 min, then add 50 g of methyl methacrylate, stir at room temperature for 1 h, at this time the system is a white turbid liquid. Then heat the system to 70℃, slowly add the initiator, and keep the temperature at this temperature overnight. After the incubation is completed, the grafted titanium dioxide particles are washed and dried under vacuum for use.

[0170] Example B1

[0171] Black and white dual-color electrophoretic display fluid and preparation method thereof

[0172] Add a certain amount of dispersion medium, charge control agent Solsperse 19000 and stabilizer polyisobutylene into a ball mill tank, then add a certain amount of zirconium beads; take the mixed black electrophoretic particles provided in Example A1 and 6 g of modified white electrophoretic particles provided in Example A13, add them into the ball mill tank, ball mill for 16 h, separate the ball mill fluid, and obtain a black and white dual-system electrophoretic display fluid.

[0173] Fill the electrophoretic display fluid into a liquid crystal cell, apply a 15V positive and negative alternating direct current voltage, and observe the display effect. The white reflectance is 35.62%, the black reflectance is 1.28%, the contrast ratio is 27.83, the black display time is 583 ms, and the white display time is 450 ms.

[0174] Example B2

[0175] Black and white electrophoretic display fluid and preparation method thereof

[0176] Black and white electrophoretic display fluid and preparation method thereof

[0177] The electrophoretic display fluid was injected into a liquid crystal cell, a positive and negative alternating direct current voltage of 15V was applied, and the display effect was observed. The white reflectance was 35.73%, the black reflectance was 1.56%, the contrast ratio was 22.9, the black display time was 304ms, and the white display time was 464ms.

[0178] Example B3

[0179] Black and white electrophoretic display fluid and preparation method thereof

[0180] The electrophoretic display fluid was injected into a liquid crystal cell, a positive and negative alternating direct current voltage of 15V was applied, and the display effect was observed. The white reflectance was 35.73%, the black reflectance was 1.56%, the contrast ratio was 22.9, the black display time was 304ms, and the white display time was 464ms.

[0181] The electrophoretic display fluid was injected into a liquid crystal cell, a positive and negative alternating direct current voltage of 15V was applied, and the display effect was observed. The white reflectance was 35.73%, the black reflectance was 1.56%, the contrast ratio was 22.9, the black display time was 304ms, and the white display time was 464ms.

[0182] Example B4

[0183] Black and white electrophoretic display fluid and preparation method thereof

[0184] The electrophoretic display fluid was injected into a liquid crystal cell, a positive and negative alternating direct current voltage of 15V was applied, and the display effect was observed. The white reflectance was 35.73%, the black reflectance was 1.56%, the contrast ratio was 22.9, the black display time was 304ms, and the white display time was 464ms.

[0185] The electrophoretic display fluid was injected into a liquid crystal cell, a positive and negative alternating direct current voltage of 15V was applied, and the display effect was observed. The white reflectance was 35.73%, the black reflectance was 1.56%, the contrast ratio was 22.9, the black display time was 304ms, and the white display time was 464ms.

[0186] Example B5

[0187] Black and white two-color electrophoretic display fluid and preparation method thereof

[0188] A certain amount of dispersing medium, charge control agent Solsperse 19000 and stabilizer polyisobutylene were added into a ball mill tank, and a certain amount of zirconium beads was added. The mixed black electrophoretic particles provided in Example A5 and 9 g of modified white electrophoretic particles provided in Example A13 were added into the ball mill tank, and ball milling was performed for 16 h. The ball milling fluid was separated to obtain a black and white two-system electrophoretic display fluid.

[0189] The electrophoretic display fluid was filled into a liquid crystal cell, a forward and reverse alternating direct current voltage of 15 V was applied, and the display effect was observed. The white reflectance was 40.61%, the black reflectance was 1.40%, the contrast ratio was 30.76, the black display time was 579 ms, and the white display time was 265 ms.

[0190] Example B6

[0191] Black and white two-color electrophoretic display fluid and preparation method thereof

[0192] A certain amount of dispersing medium, charge control agent Solsperse 19000 and stabilizer polyisobutylene were added into a ball mill tank, and a certain amount of zirconium beads was added. The mixed black electrophoretic particles provided in Example A6 and 9 g of modified white electrophoretic particles provided in Example A13 were added into the ball mill tank, and ball milling was performed for 16 h. The ball milling fluid was separated to obtain a black and white two-system electrophoretic display fluid.

[0193] The electrophoretic display fluid was filled into a liquid crystal cell, a forward and reverse alternating direct current voltage of 15 V was applied, and the display effect was observed. The white reflectance was 40.51%, the black reflectance was 1.52%, the contrast ratio was 26.65, the black display time was 432 ms, and the white display time was 240 ms.

[0194] Example B7

[0195] Black and white two-color electrophoretic display fluid and preparation method thereof

[0196] A certain amount of dispersing medium, charge control agent Solsperse 19000 and stabilizer polyisobutylene were added into a ball mill tank, and a certain amount of zirconium beads was added. The mixed black electrophoretic particles provided in Example A7 and 8 g of modified white electrophoretic particles provided in Example A13 were added into the ball mill tank, and ball milling was performed for 16 h. The ball milling fluid was separated to obtain a black and white two-system electrophoretic display fluid.

[0197] The electrophoretic display fluid was filled into a liquid crystal cell, a forward and reverse alternating direct current voltage of 15 V was applied, and the display effect was observed. The white reflectance was 39.83%, the black reflectance was 1.29%, the contrast ratio was 30.87, the black display time was 638 ms, and the white display time was 293 ms.

[0198] Example B8

[0199] Black and white two-color electrophoretic display fluid and method for preparing the same

[0200] A certain amount of dispersing medium, charge control agent Solsperse 19000 and stabilizer polyisobutylene were added into a ball mill tank, and then a certain amount of zirconium beads were added. 2 g of the mixed black electrophoretic particles provided in Example A8 and 6 g of the modified white electrophoretic particles provided in Example A13 were added into the ball mill tank, and ball milling was performed for 16 h. The ball milling fluid was separated to obtain a black and white two-system electrophoretic display fluid.

[0201] The electrophoretic display fluid was filled into a liquid crystal cell, and a forward and reverse alternating direct current voltage of 15 V was applied. The display effect was observed, and the white reflectance was 33.23%, the black reflectance was 1.23%, the contrast ratio was 27.02, the black display time was 756 ms, and the white display time was 537 ms.

[0202] Example B9

[0203] Black and white two-color electrophoretic display fluid and method for preparing the same

[0204] A certain amount of dispersing medium, charge control agent Solsperse 19000 and stabilizer polyisobutylene were added into a ball mill tank, and then a certain amount of zirconium beads were added. 2 g of the mixed black electrophoretic particles provided in Example A8 and 6 g of the modified white electrophoretic particles provided in Example A13 were added into the ball mill tank, and ball milling was performed for 16 h. The ball milling fluid was separated to obtain a black and white two-system electrophoretic display fluid.

[0205] The electrophoretic display fluid was filled into a liquid crystal cell, and a forward and reverse alternating direct current voltage of 15 V was applied. The display effect was observed, and the white reflectance was 33.23%, the black reflectance was 1.23%, the contrast ratio was 27.02, the black display time was 756 ms, and the white display time was 537 ms.

[0206] Example B10

[0207] Black and white two-color electrophoretic display fluid and method for preparing the same

[0208] A certain amount of dispersing medium, charge control agent Solsperse 19000 and stabilizer polyisobutylene were added into a ball mill tank, and then a certain amount of zirconium beads were added. 2 g of the mixed black electrophoretic particles provided in Example A8 and 6 g of the modified white electrophoretic particles provided in Example A13 were added into the ball mill tank, and ball milling was performed for 16 h. The ball milling fluid was separated to obtain a black and white two-system electrophoretic display fluid.

[0209] The electrophoretic display fluid was filled into a liquid crystal cell, a positive and negative alternating direct current voltage of 15 V was applied, and the display effect was observed. The white reflectance was 34.14%, the black reflectance was 1.34%, the contrast ratio was 25.48, the black display time was 652 ms, and the white display time was 499 ms.

[0210] Example B11

[0211] Black and white two-color electrophoretic display fluid and preparation method thereof

[0212] A certain amount of dispersing medium, charge control agent Solsperse 19000 and stabilizer polyisobutylene were added into a ball mill tank, and a certain amount of zirconium beads was added. 2 g of the mixed black electrophoretic particles provided in Example A11 and 6 g of the modified white electrophoretic particles provided in Example A13 were added into the ball mill tank, and ball milling was performed for 16 h. The ball milling fluid was separated to obtain a black and white two-system electrophoretic display fluid.

[0213] The electrophoretic display fluid was filled into a liquid crystal cell, a positive and negative alternating direct current voltage of 15 V was applied, and the display effect was observed. The white reflectance was 34.14%, the black reflectance was 1.34%, the contrast ratio was 25.48, the black display time was 652 ms, and the white display time was 499 ms.

[0214] Example B10

[0215] Black and white two-color electrophoretic display fluid and preparation method thereof

[0216] A certain amount of dispersing medium, charge control agent Solsperse 19000 and stabilizer polyisobutylene were added into a ball mill tank, and a certain amount of zirconium beads was added. 2 g of the mixed black electrophoretic particles provided in Example A11 and 6 g of the modified white electrophoretic particles provided in Example A13 were added into the ball mill tank, and ball milling was performed for 16 h. The ball milling fluid was separated to obtain a black and white two-system electrophoretic display fluid.

[0217] The electrophoretic display fluid was filled into a liquid crystal cell, a positive and negative alternating direct current voltage of 15 V was applied, and the display effect was observed. The white reflectance was 34.14%, the black reflectance was 1.34%, the contrast ratio was 25.48, the black display time was 652 ms, and the white display time was 499 ms.

[0218] Comparative Example 1

[0219] Electrophoretic display fluid and preparation method thereof

[0220] A certain amount of dispersing medium, charge control agent Solsperse 19000 and stabilizer polyisobutylene were added into a ball mill tank, then a certain amount of zirconium beads were added, 1 g of the modified first electrophoretic particle (modified copper-chromium black particle) in Example Al and 7 g of the modified titanium dioxide pigment in Example Al l were added into the ball mill tank, and ball milling was performed for 16 h. The ball milling liquid was separated to obtain a black-white dual system electrophoretic display liquid. The electrophoretic display liquid was filled into a liquid crystal cell, a forward and reverse alternating direct current voltage of 15 V was applied, and the display effect was observed. The white reflectance was 34.63%, the black reflectance was 2.31%, the contrast ratio was 14.99, the black display time was 392 ms, and the white display time was 279 ms.

[0221] Comparative Example 2

[0222] Electrophoretic display liquid and method for preparing the same

[0223] A certain amount of dispersing medium, charge control agent Solsperse 19000 and stabilizer polyisobutylene were added into a ball mill tank, then a certain amount of zirconium beads were added, 1 g of the modified second electrophoretic particle (modified manganese-iron black particle) in Example Al and 7 g of the modified titanium dioxide pigment in Example Al l were added into the ball mill tank, and ball milling was performed for 16 h. The ball milling liquid was separated to obtain a black-white dual system electrophoretic display liquid. The electrophoretic display liquid was filled into a liquid crystal cell, a forward and reverse alternating direct current voltage of 15 V was applied, and the display effect was observed. The white reflectance was 36.62%, the black reflectance was 1.25%, the contrast ratio was 29.30, the black display time was 1238 ms, and the white display time was 859 ms.

[0224] Comparative Example 3

[0225] Electrophoretic display liquid and method for preparing the same

[0226] A certain amount of dispersing medium, charge control agent Solsperse 19000 and stabilizer polyisobutylene were added into a ball mill tank, then a certain amount of zirconium beads were added, 1 g of the modified second electrophoretic particle (modified manganese-iron black particle) in Example Al and 7 g of the modified titanium dioxide pigment in Example Al l were added into the ball mill tank, and ball milling was performed for 16 h. The ball milling liquid was separated to obtain a black-white dual system electrophoretic display liquid. The electrophoretic display liquid was filled into a liquid crystal cell, a forward and reverse alternating direct current voltage of 15 V was applied, and the display effect was observed. The white reflectance was 36.62%, the black reflectance was 1.25%, the contrast ratio was 29.30, the black display time was 1238 ms, and the white display time was 859 ms.

[0227] Table 1

[0228] White reflectance Black reflectance Contrast ratio Black-up time White-up time Example B1 0.3562 0.0128 27.83 583 ms 450 ms Example B2 0.3573 0.0156 22.9 304 ms 464 ms Example B3 0.3556 0.014 25.4 352 ms 456 ms Example B4 0.3521 0.0135 26.08 383 ms 434 ms Example B5 0.4061 0.0132 30.76 579 ms 265 ms Example B6 0.4051 0.0152 26.65 432 ms 240 ms Example B7 0.3983 0.0129 30.87 638 ms 293 ms Example B8 0.4032 0.0138 29.22 488 ms 268 ms Example B9 03323 0.0123 27.02 756 ms 537 ms Example B10 0.3414 0.0134 25.48 652 ms 499 ms Example B11 0.3571 0.0137 26.07 856 ms 503 ms Example B12 0.3496 0.0132 26.48 938 ms 550 ms Comparative Example 1 0.3463 0.0231 14.99 392 ms 279 ms Comparative Example 2 0.3662 0.0125 29.3 1238 ms 859 ms Comparative Example 3 0.3662 0.0134 27.33 916 ms 645 ms

[0229] According to Table 1, in combination with Examples B1-B4 and Comparative Example 1, it can be seen that after adding the modified second black particles, the black reflectance is reduced, and the more the modified second black particles are added, the lower the reflectance is, and the higher the contrast of the final electrophoretic display is, but the more the modified second black particles are added, the longer the black display time is; the specific surface area of the modified second black particles in Examples B5-B8 is greater than that of the modified second black particles in Examples B1-B4, and by comparing Comparative Example B7 with B1, Example B6 with B2, Example B8 with B3, and Example B5 with B4, it can be seen that the black reflectance is lower than that of Examples B1-B4, but because the density of the modified second black particles is greater, the black display time is also longer; by comparing Example B9 with B1, it can be seen that the greater the density of the modified first black particles is, the longer the black display time is, and the greater the specific surface area of the modified first black particles is, the higher the black reflectance is. It can be seen from Comparative Examples 2 and 3 that when the content of the modified second black particles is too high, the black display time is too long, and the display effect is poor.

[0230] In summary, the electrophoretic display fluid provided herein contains the mixed black electrophoretic particles provided in the embodiments, and because the mixed black electrophoretic particles contain the modified first black electrophoretic particles with relatively small density and the modified second black electrophoretic particles with relatively large density and specific surface area, the modified first black electrophoretic particles with relatively small density have a similar density to the dispersion medium in the electrophoretic fluid, which can improve the electrophoretic speed of the electrophoretic particles and improve the response speed; further, the modified second black electrophoretic particles with relatively large density and specific surface area are used in combination, and the modified second black electrophoretic particles have a large specific surface area, which can improve the black value of the mixed black electrophoretic particles as a whole, improve the contrast of the mixed black electrophoretic particles in the electrophoretic system, and obtain mixed black electrophoretic particles with excellent properties of fast response speed and high contrast. Therefore, the electrophoretic display fluid has excellent performance.

[0231] The preferred embodiments of the present application have been described above with the preferred embodiments, but the present application is not limited to the above, and any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A mixed black electrophoretic particle, characterized in that, The mixed black electrophoretic particles comprise modified first black electrophoretic particles having a density of 0.60 to 1.38 kg / L and modified second black electrophoretic particles having a density of 1.40 to 5.04 kg / L and a specific surface area > 15 m 2 / g.

2. The mixed black electrophoretic particles of claim 1, wherein, The density of the modified first black electrophoretic particle differs from the density of the dispersion medium of the electrophoretic fluid by 0% to 100%.

3. The mixed black electrophoretic particles of claim 2, wherein, The density of the modified first black electrophoretic particle differs from the density of the dispersion medium of the electrophoretic fluid by 0% to 50%.

4. The mixed black electrophoretic particles of claim 1, wherein, The modified first black electrophoretic particle is a first black electrophoretic particle with a polymer connected to the surface, and the density of the obtained modified first black electrophoretic particle is 0.60 to 1.38 kg / L; and / or, The modified second black electrophoretic particles are second black electrophoretic particles having a polymer attached to the surface, the density of the resulting modified second black electrophoretic particles is 1.40 to 5.04 kg / L, and the specific surface area of the modified second black electrophoretic particles is > 15 m 2 / g.

5. The mixed black electrophoretic particles of claim 4, wherein, The polymer comprises at least one of polyethylene, polypropylene, polyacrylate, polyurethane, polyester, polysiloxane; and / or, The first black electrophoretic particle comprises at least one of copper chromium black, pigment black 32, antimony sulfide, carbon black, manganese iron black, iron oxide black, iron chromium black, cobalt black; and / or, The second black electrophoretic particle comprises at least one of copper chromium black, pigment black 32, antimony sulfide, carbon black, manganese iron black, iron oxide black, iron chromium black, cobalt black.

6. The mixed black electrophoretic particles of claim 1, wherein, The mass ratio of the modified first black electrophoretic particle and the modified second black electrophoretic particle is 1:0.01 to 1.

7. The mixed black electrophoretic particles of claim 1, wherein, The particle size of the modified first black electrophoretic particle is 180 to 240 nm; and / or, The particle size of the modified second black electrophoretic particle is 180 to 240 nm.

8. A method for preparing the mixed black electrophoretic particles according to any one of claims 1 to 7, characterized by, Comprising the following steps: At least two black electrophoretic particles are provided; The black electrophoretic particles and silane coupling agent, polymer monomer, solvent are mixed, and the modification reaction is carried out respectively, the polymer is grafted on the surface of the black electrophoretic particles through the silane coupling agent respectively, to obtain modified first black electrophoretic particles and modified second black electrophoretic particles, wherein the density of the modified first black electrophoretic particles is 0.60~1.38 kg / L, the density of the modified second black electrophoretic particles is 1.40~5.04 kg / L, and the specific surface area of the modified second black electrophoretic particles is >15m 2 / g.

9. The method for preparing mixed black electrophoretic particles according to claim 8, characterized in that, The silane coupling agent is selected from at least one of a silane comprising a methacryloyloxy group and a double bond, a silane comprising an aminoalkyl group and a double bond group; The polymer monomer is selected from at least one of lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hexyl acrylate, hexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, n-octadecyl acrylate, n-octadecyl methacrylate; The solvent is selected from at least one of ethanol, benzene, toluene and xylene; and / or, The mass ratio of the black electrophoretic particle, the silane coupling agent, the polymer monomer, the solvent is 1:0.1-0.3:0.8-2:1-8.

10. A black and white electrophoretic display fluid, characterized in that The total mass of the black and white electrophoretic display fluid is 100%, comprising the following components by weight percentage: Electrophoretic particles 10% to 50%, Charge control agent 2% to 15%, Stabilizing agent 0.1% to 1%, Dispersion medium 46% to 87.9%; The electrophoretic particles comprise mixed black electrophoretic particles and modified white electrophoretic particles in a mass ratio of 1:1 to 10, the mixed black electrophoretic particles are the mixed black electrophoretic particles of any one of claims 1 to 7 or prepared by the preparation method of the mixed black electrophoretic particles of claim 8 or 9.

11. An electrophoretic display device, characterized by The electrophoretic display device comprises a substrate and an electrophoretic display layer laminated on any one side of the substrate, wherein the electrophoretic display layer is obtained by coating and drying the black and white electrophoretic display fluid of claim 10.

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