KR101133071B1 - Electrophoretic Particles, Eletrophoretic Medium and Electrophoretic Display Device Comprising the Same - Google Patents

Abstract

The present invention relates to an electrophoretic particle, an electrophoretic medium and an electrophoretic display including the same, specifically, the electrophoretic particle of the present invention comprises a polymer backbone and one or more ionic bond groups bonded on the backbone, Binder resin having a particle shape; A color material dispersed on the binder resin; A charge control agent dispersed on the binder resin; And a surfactant secondary bonded to the ion bond group, wherein at least a part of the surfactant secondary bond to the ion bond group on the polymer main chain is exposed to the particle surface.
The electrophoretic particles are simple and easy to manufacture, but have less agglomeration between particles, which may result in improved image stability and faster response when applied to an electrophoretic display, thereby providing an electrophoretic display including electrophoretic particles. It can be usefully used in the industrial field related to manufacturing.

Description

Electrophoretic Particles, Electrophoretic Media and Electrophoretic Displays Comprising the Same {Electrophoretic Particles, Eletrophoretic Medium and Electrophoretic Display Device Comprising the Same}

The present invention relates to electrophoretic particles, electrophoretic media and electrophoretic displays comprising the same. More specifically, the present invention relates to an electrophoretic particle and a method for manufacturing the same, which are simple and easy to produce, but have less agglomeration between particles, thereby exhibiting improved image stability and fast response speed.

Electronic Paper (Digital Paper), also called E-paper, is an electronic device that can act as a paper because it can be conveniently carried like paper books, paper newspapers and paper magazines, easily taken out whenever necessary, and memos can be taken. Say. Such electronic paper is no longer just a science fiction movie or a future product. A lot of research and development has already been carried out, and some products are commercialized to form a market.

Representative particle technology-driven electronic papers that have progressed to the commercialization stage or near the commercialization stage include electrophoresis, particle rotation, and dry transfer, and E-ink, Zyricon, and Bridgestone are developing and commercializing the technology. In particular, the Massachusetts Institute of Technology (MIT) and E-Ink have been intensively developing encapsulated electrophoretic media containing pigment particles.

On the other hand, the research and development focus of the encapsulated electrophoretic medium containing the pigment particles is in the implementation of improved image stability and fast switching speed. For this purpose, electrophoretic particles including pigments included in the electrophoretic display should be able to move quickly in a medium to which an electric field is applied, and the aggregation between particles should occur less for improved image stability and color realization.

Accordingly, interest has been amplified for the development of electrophoretic particles including pigment particles with less aggregation phenomenon between the electrophoretic particles and improved mobility in the medium. Thus, US-2009-0009852 of E-Ink discloses a method for producing electrophoretic particles by surface treatment of a pigment with an ionic monomer followed by two stages of polymerization. However, according to the method disclosed in US2009-0009852, after the process of treating the ionic monomer to the pigment particles and the polymerization process of each subsequent step, the operation of centrifuging the polymerization product of the pigment particles and the remaining monomers, etc. Since it must be repeated, the manufacturing process is cumbersome, and it is difficult to control the degree of polymerization in order to obtain a desired degree of steric hindrance.

Thus, the inventors of the present invention, while minimizing the coagulation between the electrophoretic particles, while completing a study on a method for producing an electrophoretic particles is easy to complete the present invention.

The present invention provides an electrophoretic particle that is simple and easy to produce, but has little aggregation between particles, resulting in improved image stability and fast response speed.

The present invention also provides an electrophoretic medium and an electrophoretic display comprising the electrophoretic particles.

The present invention is a binder resin comprising a polymer backbone and at least one ion bond group bonded on the backbone, wherein the polymer backbone has a particle shape; A color material dispersed on the binder resin; A charge control agent dispersed on the binder resin; And a surfactant secondaryly bonded to the ionic bond group, and at least a portion of the surfactant secondaryly bonded to the ionic bond group on the polymer backbone provides electrophoretic particles of a type exposed to the particle surface.

The present invention also provides an electrophoretic medium comprising one or more electrophoretic particles dispersed in an insulating medium.

The present invention also provides an electrophoretic display comprising a pair of electrodes comprising at least one transparent electrode and the electrophoretic medium between the electrodes.

Hereinafter, electrophoretic particles, electrophoretic media, and electrophoretic displays according to specific embodiments of the present invention will be described.

According to one embodiment of the present invention, a binder resin comprising a polymer main chain and at least one ion bond group bonded on the main chain, wherein the polymer main chain has a particle shape; Colorants dispersed on the binder resin; A charge control agent (CCA) dispersed on the binder resin; And a surfactant secondaryly bonded to the ionic bond group, wherein at least a portion of the surfactant secondaryly bonded to the ionic bond group on the polymer main chain is provided with electrophoretic particles. In this case, the secondary bond refers to a bonding mode including ion-ion bonds, dipole-dipole bonds, van der Waals bonds, and ion-dipole bonds as bonds other than primary bonds such as ionic bonds, covalent bonds, and metal bonds. .

On the other hand, the cross-section of the electrophoretic particles according to the embodiment as shown in Figure 1 briefly. As shown in FIG. 1, the binder resin including the polymer main chain 12 and at least one ion bond group 16 bonded to the main chain has a particle shape, and a surfactant secondary bonded to the ion bond group on the polymer main chain ( At least a portion of 40) is exposed to the particle surface. In addition, as shown in FIG. 1, the color material 20 and the charge control agent 30 are dispersed on the above-described particulate binder resin. At this time, the stereoscopic boundary 50 of Figure 1 may be defined as the thickness from the particle surface formed by the surfactant exposed on the surface of the electrophoretic particles, electrophoretic particles of another embodiment to be described later (see Figure 2) In, it can be defined as the thickness from the surface of the particles by the surfactant exposed to the surface of the electrophoretic particles and the sub chain covalently bonded to the main chain. Due to the presence of such steric hindrance boundary 50, aggregation between the electrophoretic particles can be minimized.

The present inventors through the experiment, the steric hindrance between the electrophoretic particles 100 by the surfactant (40) secondary bonded to the ion coupler on the polymer backbone exposed to the surface of the electrophoretic particles 100 as described above The phenomenon appeared, it was found that the principle of aggregation between particles can be minimized by this principle. In addition, since the electrophoretic particles can be manufactured through a simple process, it is expected that the electrophoretic particles can be widely applied to an industrial field related to electrophoretic displays.

On the other hand, unless otherwise stated, some terms used throughout this specification are defined as follows.

Throughout this specification, “electrophoretic particles” refers to particles that can be charged and contain colorants that can be used in electrophoretic displays. In addition, throughout this specification, "binder resin" refers to a resin that forms the outer shell of the electrophoretic particles according to the present invention, and the singular number of the polymer including the polymer main chain and one or more ionic bond groups secondary bonded to the main chain. Or a particulate resin formed by a plurality of main chains. In addition, the polymer backbone of the binder resin has a "particle shape". The "particle shape" has one or more of the polymer backbones to form an outline to have a certain volume in space and may contain certain materials therein. Refers to having a shape, the shape is not limited, such as spherical, polyhedral, egg-shaped, or potato. In addition, the colorant or the charge control agent (CCA) is "dispersed on the provider resin" means that the colorant or charge control agent is physically uniformly spread inside the particle shape of the polymer backbone of the binder resin. it means.

On the other hand, throughout the present specification, the "first organic solvent" is shared with the polymer backbone, which is secondary bonded to the polymer backbone and at least one ionic bond group bound on the backbone, or the polymer backbone defined according to another embodiment of the present invention. Refers to an organic solvent having substantially the same solubility in bound subchains, solubility ratio for the main chain of binder resin and the surfactant secondary bonded to one or more ionic bonders bound on the main chain, or the main chain of binder resin and the subchain The solubility ratio for is generally within the range of 0.8 to 1.2 to refer to an organic solvent having substantially the same solubility for the polymer main chain, the surfactant secondary bonded to the ionic bond group, and the sub chain.

Finally, throughout this specification, “second organic solvent” refers to an organic solvent having a solubility in the polymer backbone that is 10% or less lower than the solubility in the secondary chain and / or the surfactant secondaryly bonded to the ionic bond group. . In addition, the "second organic solvent" may also refer to an organic solvent having a solubility of 10% or less than the first organic solvent with respect to the polymer backbone.

On the other hand, the binder resin of the electrophoretic particles further comprises at least one sub chain covalently bonded to the main chain, at least a portion of the sub chain is exposed to the particle surface, the ion bond group is covalently bonded on the main chain It may be in the form. At this time, the main chain may have a solubility in the second organic solvent of 10% or less than the solubility in the predetermined first organic solvent, and also the surfactant or secondary chain secondary bonded to the ion-bonding group to the second organic solvent. Lower solubility of less than 10%.

This will be described in more detail in the method of preparing the electrophoretic particles of the present application to be described later, but as the main chain exhibits such solubility characteristics, in the presence of the second organic solvent during the electrophoretic particle manufacturing step, the polymer backbone is placed inside the electrophoretic particles It is possible to properly bind the charge control agent and the colorant included, and one or more ionic bond groups bound on the main chain can be exposed to the surface of the particles with a surfactant bonded to the ion coupler to minimize aggregation with other electrophoretic particles. It can be manufactured so that.

On the other hand, in the electrophoretic particles according to the embodiment described above, the main chain has a solubility of 0.005 g / ml or less with respect to the second organic solvent, has a solubility of 0.05 to 1 g / ml with respect to the first organic solvent, The surfactant secondary bonded to the ion bond group may have a solubility of 0.05 g / ml or more with respect to the first and second organic solvents. By appropriately selecting a surfactant secondary bonded to the polymer backbone and the ion bond group having a difference in solubility as described above, it is possible to produce electrophoretic particles that can minimize the aggregation effect between particles in a simpler method.

That is, the principle of producing the electrophoretic particles according to the above-described embodiment of the present invention is to use the difference in solubility of the polymer main chain and the surfactant secondary bonded to the ion bond group in the second organic solvent, and the secondary bond to the main chain and the ion bond group. To the surfactant, using a solvent having substantially the same solubility (“first organic solvent” as defined above), a colorant; a charge control agent (CCA); one or more ionic bonders bound on the polymer backbone and the backbone And a solvent having a lower solubility of 10% or less than the first organic solvent in the polymer main chain after dissolving the surfactant, and then dissolving the surfactant in the first organic solvent. Solvent), and then electrophoretic particles are prepared by removing the first organic solvent.

In this case, as defined above, the second organic solvent has a solubility of 10% or less than the surfactant secondaryly bonded to the ionic bond group with respect to the main chain, or 10% or less than the first organic solvent with respect to the main chain. Since it has a low solubility, the main chain of the single or plural polymers added dropwise to the second organic solvent may be entangled with each other to form a binder resin having a particle shape, wherein at least some of the color material and the charge control agent It can be bound and dispersed on the binder resin. On the other hand, since the surfactant secondary bonded to one or more ionic bond groups bonded to the main chain has a higher solubility than the main chain for the second organic solvent, the surfactant is formed in the form exposed to the particle surface of the particulate binder resin in the presence of the second organic solvent. Thus, at least a part can be produced in a form exposed to the particle surface.

On the other hand, the present invention further provides an electrophoretic particle further comprises at least one sub chain covalently bonded to the main chain of the binder resin, wherein at least a portion of the sub chain is exposed to the particle surface. Specifically, the electrophoretic particles according to the above embodiment, the main chain has a solubility of 0.005 g / ml or less in the second organic solvent, has a solubility of 0.05 to 1 g / ml in the first organic solvent, The subchain may have a solubility of at least 0.05 g / ml for the first and second organic solvents.

That is, the main chain may have a solubility of 10% or less than the sub chain in the second organic solvent. Thus, the coloring material; Charge control agents; A polymer backbone, a polymer comprising one or more ionic bond groups bound on the backbone; And when the solution in which the surfactant is dissolved in a predetermined first organic solvent is added dropwise to the second organic solvent having a solubility of 10% or less than the sub chain described above with respect to the main chain described above, the main chains may be entangled with each other to form a particle shape. And the sub chains are exposed to the surface of the particles.

FIG. 2 schematically shows a cross section of the electrophoretic particles in which at least a portion of the sub chain 18 is exposed to the particle surface as described above. Also in the electrophoretic particles according to the above embodiment, the solubility of the sub chain and the main chain and the surfactant secondaryly bonded to the ionic bond group in the first organic solvent is substantially the same, their solubility ratio is 0.8 to 1.2. to be. As described above, the solubility of the secondary chain, the main chain, and the surfactant secondaryly bonded to the ionic bond group to the first organic solvent should be in substantially the same range, so that the colorant, the charge control agent, etc. dissolved in the first organic solvent are evenly dispersed. When added to the second organic solvent, the colorant and the charge control agent may be uniformly included in the electrophoretic particles.

In addition, according to another embodiment of the present invention, the binder resin includes a plurality of polymer backbones, one or more backbones include one or more subchains covalently bonded thereto, and the plurality of backbones have a particle shape. Provides phoretic particles. Such electrophoretic particles may comprise at least a portion of a surfactant secondary to the ionic bond of the polymer backbone, and at least a portion of one or more subchains covalently bonded to another polymer backbone and a surfactant secondary to the ionic bond of these polymer backbones. Aggregation between particles can be minimized by at least a part of the surface exposed to the particle surface, and the steric hindrance boundary formed by these surfactants and subchains. Therefore, when the electrophoretic particles are applied to the electrophoretic display, it is expected to exhibit improved image stability and fast response speed.

On the other hand, the main chain of the electrophoretic particles according to the above-described embodiments of the present invention, solubility of 10% or less than the surfactant secondary bond to the ionic bond group or the secondary chain covalently bonded to the main chain, respectively, for the second organic solvent If it has a, it may include a specific repeating unit without limiting the configuration. As a specific example, the main chain may include one or more repeating units selected from the group consisting of polyester, polyamide, polyurethane, polyacrylate, and polystyrene. have.

In addition, in the above-described embodiments of the present invention, the subchains of the electrophoretic particles in which at least a part of the subchains are exposed to the particle surface are isobutylene, hexylmethacryalte, laurylmethacrylate. (laurylmethacrylate), methyl methacrylate (methylmethacrylate) and styrene (styrene) containing one or more repeating units, the electrophoretic particles of such electrophoretic particles, the main chain (polyester), polyamide (polyamide), It may include one or more repeating units selected from the group consisting of polyurethane, acrylester, and urethane ester.

On the other hand, the colorant (colorant) included in the electrophoretic particles may be used commercially commonly used pigments (pigment), dye (dye), or a mixture thereof. Specifically, as the pigment, cyan pigment, magenta pigment, yellow pigment, black pigment and white pigment or mixtures thereof, which are commonly used pigments, are appropriately selected in consideration of color, saturation, lightness, weather resistance, transparency, and the like. Can be used. Examples of such pigments include P.Y 155, P.Y 180, and magenta. 57: 1, P.R. 184, P.R. 122, P.B 15: 3 or the like is often used as the pure color of the cyan color. In addition, pigments included in the electrophoretic nanoparticles are P.Y 17, P.Y. 97, P.Y. 174, P.Y. 139, P.X. 139. P.O. Yellow and 34 R.R. 146, P.V. Magenta tone pigments such as 19, pigments such as P. V. 23, P. V. 19, P. G. 7 and P. B. 15: 4 can be used. In addition, black, such as SB4, SB7, SB9, can be used as a black color, and it can manufacture using titanium oxide as a white pigment. These selection criteria can be selected appropriately from the above group in consideration of color coordinates and color depth.

In addition, as the dye, commercially commonly used cationic dyes, anionic dyes, disperse dyes or mixtures thereof may be appropriately selected in consideration of hue, saturation, lightness, weather resistance, transparency, and the like.

On the other hand, the particle size and content of the colorant included in one electrophoretic particle is not limited, but considering the main chain length of the binder resin and the amount of the charge control agent contained in the electrophoretic particles, 3 to 40 to the total weight of the electrophoretic particles Wt% may be included. In addition, the color material can use a volume average particle diameter of 10 nm-400 nm.

On the other hand, as the charge control agent, one or more of a positive charge control agent, a negative charge control agent or a mixture thereof commonly used may be used without limitation, and may be appropriately selected and used depending on the charge to be imparted to the final electrophoretic particles. Positive charge control agents are classified into azine and quaternary ammonium salts due to their chemical structure.As the positive charge control agents of the azine type are mainly black, they can be used mainly for the production of black particles. Since the quaternary ammonium salt is in the form of a white powder, it can be used without restriction on the color of the final particles to be produced.

Negative charge control agents are generally used in the tert- butyl salicylic acid metal salt-based white charge regulators and azo black charge regulators. As the center metal in the tert-butyl salicysilane metal salt, chromium, aluminum, zinc, a capsule, boro, acetyl boron, and the like are used. In the case of the azo system, chromium, iron and the like are mainly used. The metal salt used at this time functions to control the moving speed, the moving amount, etc. of the electrophoretic particles when an electric field is applied to the electrophoretic medium. When the amount of the charge control agent is too small, since the moving speed of the electrophoretic particles may be a problem in the contrast ratio and response speed, it is preferable to include 3% by weight or more, if the 3% by weight or more, there is no limitation in the configuration, More preferably included in 3 to 40% by weight relative to the weight of the final electrophoretic particles to be produced.

On the other hand, the one or more ionic bond groups bonded to the main chain of the electrophoretic particles of the above-described example is not limited as long as it is a suitable functional group capable of secondary bonding with the surfactant. Specifically, the ion bonding group is an carboxyl group, a sulfonic acid group, a phosphoric acid group, a sulfate group, an acid group of a sulfonate group; Base groups of amine groups, ammonium groups, and imine groups; And it may be at least one selected from the group consisting of sodium sulfonate salt, potassium sulfonate salt, sodium phosphate salt, potassium phosphate salt, amine salt (salt).

In this case, when the ion-bonding group is selected from an acid group such as a carboxyl group, a cationic surfactant is selected from a base group such as an amine group, and an anionic surfactant is selected from the group of a base group such as an amine group. Surfactants, cationic surfactants, or nonionic surfactants may be combined. As described above, at least a part of the surfactant secondaryly bonded to the ion coupler is exposed to the surface of the electrophoretic particles, thereby minimizing the aggregation between the particles. On the other hand, more preferably, the ion bonding group may be selected from the acid group or base group group rather than the salt group. Accordingly, since the ionic bond group can secondary bond more strongly with the surfactant, the surfactant or the like exposed on the surface of the particles can more effectively suppress aggregation between the particles.

The surfactant that can be used at this time is a commercially available, and can be selected and used without limitation if the anionic surfactant, cationic surfactant, nonionic surfactant, and the like readily available. Specific examples include one or more cationic surfactants selected from the group consisting of amine salts and alkyl ammonium; at least one anionic surfactant selected from the group consisting of α-olefin sulfonates, alkyl sulfate ester salts, alkyl ether sulfates, and alkyl sulfonates; Or at least one nonionic surfactant selected from the group consisting of polyisobutylene succinimide, and polyoxyethylene lauryl ether, but the present invention is not limited thereto. .

On the other hand, the electrophoretic particles according to the above-described embodiments of the present invention may have a volume average particle diameter of 50 to 3000 nm, preferably 50 to 1500 nm, in consideration of a moving speed when an electric field is applied.

As described above, the electrophoretic particles according to the embodiments of the present invention form steric hindrance between particles by a secondary bond to the ionic bonder exposed on the particle surface and / or a subchain covalently bonded to the polymer backbone. Thus, aggregation between particles can be minimized. Preferably, the surfactant or the sub chain may be exposed to the surface of the particle by the number average molecular weight 500g to 10,000 per mole of electrophoretic particles. When at least a portion of the surfactant or the sub chain is exposed to the particle surface as described above, when applying an electric field applied to an electrophoretic display, etc., aggregation between particles can be minimized without affecting the moving speed of the particles. .

In accordance with another embodiment, the present invention provides an electrophoretic medium comprising one or more electrophoretic particles dispersed in a dielectric fluid. The electrophoretic particles included in the above-mentioned electrophoretic medium include electrophoretic particles of the above-described embodiments according to the present invention. In this case, the electrophoretic medium may further include a capsule containing the electrophoretic particles dispersed in the insulating medium according to an embodiment. The electrophoretic medium according to this embodiment is called a capsule type electrophoretic medium, and may be manufactured in various forms according to the type of electrophoretic display to be applied. That is, the electrophoresis includes only electrophoretic particles having a single charge and a single color, or includes electrophoretic particles having a single charge but having different colors of colorants, or having the same color, but having different charges. The configuration, such as the form containing particles may be different in various ways depending on the electrophoretic display to be applied, it is not limited to the above examples.

In this case, the dielectric fluid may be an aliphatic hydrocarbon or a mixture of a halogenated hydrocarbon and an aliphatic hydrocarbon.

On the other hand, the present invention provides an electrophoretic display comprising a pair of electrodes including at least one transparent electrode and the above-mentioned electrophoretic medium between the electrodes. When the electric field is applied through the electrode of the electrophoretic display as described above, the electrophoretic medium including the electrophoretic particles is arranged in an appropriate position according to the amount of charge and the nature of the charge of the contained particles, the display according to the arrangement The desired text or picture will be displayed on the screen.

The electrophoretic display as described above is not limited to the application target product. Specifically, a portable computer, an electronic book, a mobile phone, a smart card, an advertisement display panel, or a display device of a watch may be mentioned, but is not limited to the above-described example.

On the other hand, the manufacturing method of the electrophoretic particles according to an embodiment of the present invention, specifically, a colorant (colorant); Charge control agents (CCA); A polymer main chain having one or more ionic bond groups bound thereto; And dissolving the surfactant in a predetermined first organic solvent; And dropping the solution dissolved in the first organic solvent into a second organic solvent having a solubility in the polymer backbone having a solubility lower than 10% of the first organic solvent, and then removing the first organic solvent. Steps.

As described above, when dissolving the colorant or the like described above in a predetermined first organic solvent whose solubility in the polymer backbone and the surfactant is substantially the same, in the first solution, some of the surfactant is bound on the polymer backbone. Secondary bonds to the above ionic bond groups. When it is added dropwise to the second organic solvent again, since the second organic solvent has a solubility of 10% or less of the first organic solvent with respect to the main chain, the polymer main chains are entangled with each other in the presence of the second organic solvent. Agglomerated with each other to form a particle shape to form a binder resin, a portion of the charge control agent and the colorant added dropwise together to the second organic solvent is included in the binder resin of the particle shape, and is secondary bonded to the ion coupler The surfactant will be exposed to the surface of the particles.

Meanwhile, according to another embodiment of the present invention, a polymer including a sub chain covalently bonded to the main chain may be further dissolved in a second solvent having a solubility in the main chain lower than 10% of the solubility in the main chain. have. Through such a method, electrophoretic particles having a form in which at least a part of the above-described sub chain is exposed to the particle surface together with the surfactant secondaryly bonded to the ion bonder can be prepared.

In this case, in order to prepare in the form of electrophoretic particles in which at least a portion of the surfactant and / or the secondary chain secondaryly bonded to the ionic bond group on the polymer main chain is exposed to the particle surface, a solution dissolved in the first organic solvent is added to the second solvent. At the time of dropping, it is possible to proceed at a dropping rate of 1 to 10 ml / min, preferably at a temperature of 10 to 80 ° C. Under the above conditions, an appropriate amount of the charge control agent and the colorant may be dispersed on the binder resin, and the remainder of the main chain except the polymer main chain or both ends may be entangled with each other to obtain a certain particle shape.

In the manufacturing method according to the embodiments described above, the main chain of the polymer main chain to which at least one ion-bonding group is bonded is polyester, polyamide, polyurethane, polyacrylate, And it may include one or more repeating units selected from the group consisting of polystyrene.

In addition, in the manufacturing method according to the embodiments described above, the sub chain of the polymer comprising a sub chain covalently bonded to the main chain isobutylene (isobutylene), hexyl methacrylate (hexylmethacryalte), lauryl methacrylate ( one or more repeating units selected from the group consisting of laurylmethacrylate, methylmethacrylate and styrene,

The main chain may include one or more repeating units selected from the group consisting of polyester, polyamide, polyurethane, acrylic ester, and urethane ester.

That is, in order to produce electrophoretic particles in which at least a part of the surfactant secondaryly bonded to the ionic bond group on the polymer main chain or at least a part of the subchain covalently bonded to the main chain is exposed together with the surfactant to the particle surface, The repeating unit of the main chain and the sub chain of the polymer may be designed differently so that the solubility differs with respect to the organic solvent.

On the other hand, as already described above in the embodiment of the electrophoretic particles, the ionic bond group bonded on the main chain may include a functional group capable of secondary bonding with the surfactant. Specifically, the ion bonding group is an carboxyl group, a sulfonic acid group, a phosphoric acid group, a sulfate group, an acid group of a sulfonate group; Base groups of amine groups, ammonium groups, and imine groups; And it may be one selected from the group consisting of sodium sulfonate salt, potassium sulfonate salt, sodium phosphate salt, potassium phosphate salt, amine salt (salt).

In addition, the surfactant used at this time is an anionic surfactant, cationic surfactant, or nonionic surfactant, the specific configuration of which is as described above in the embodiment for the electrophoretic particles.

As the charge control agent used in the production method according to the above embodiments, the specific type and the content of the electrophoretic particles as the positive charge control agent, the negative charge control agent or a mixture thereof may be as mentioned in the above-described embodiments of the electrophoretic particles. same.

In addition, in the manufacturing method of this application, in consideration of the kind of repeating unit which comprises the main chain or sub chain | strand of binder resin, etc., the appropriate solvent which has solubility selectively in these main chains or sub chains can be selected.

That is, the first organic solvent described above refers to an organic solvent having substantially the same solubility in surfactants secondary bonded to the polymer main chain, the secondary chain, and the ion bond group, and an interface secondary bonded to the polymer main chain, the secondary chain, and the ion bond group. As long as each solubility ratio for the active agent is in the range of 0.8 to 1.2, it can be selected regardless of its configuration. The composition is not limited, but specifically, in the group consisting of toluene, acetone, methylethylketone, methylene chloride, ethylene chloride and tetrahydrofuran One or more organic solvents selected may be used.

On the other hand, as defined above, the second organic solvent is a surfactant secondaryly bonded to the ionic bond group to the main chain of the binder resin, an organic solvent having a solubility of 10% or less than a subchain covalently bonded to the main chain, or a polymer main chain, respectively. As long as it has a solubility of 10% or less than that of the first organic solvent, it can be used without limitation in the constitution. Specifically, one or more selected from the group consisting of alcohols, hydrocarbon-based organic solvents, isoparaffinic solvents, and halocarbon-based oils may be used.

At this time, specific examples of the alcohol may be methanol (methanol), ethanol (ethanol), propanol (propanol), isopropanol (isopropanol), isobutanol (isobutanol) or a mixture of one or more selected from these, but is not limited to the above examples Do not. In addition, the hydrocarbon-based organic solvent may be specifically hexane, heptane, nonane, or one or more mixtures thereof, but is not limited to the above-described example.

In addition, the isoparaffin solvent is not limited in its configuration, but preferably, Isopar series supplied from Exxon may be used. In addition, the halocarbon-based oil may be used at least one selected from Halocarbon oil 0.8, Halocarbon oil 1.8, and mixtures thereof, but is not limited to the above examples.

On the other hand, as described above, the particles formed in the presence of the second organic solvent is removed in the electrophoretic particles and unreacted materials using a centrifugal separator, and then dried in the form of electrophoretic particles having a volume average particle size of 50 to 3000nm. Can be. Preferably, the volume average particle diameter of the electrophoretic particles may be 50 to 1500 nm.

At this time, the drying step is not limited to the configuration, but may be used, such as evaporation, centrifugation, fluid replacement method, when using the evaporation method, it can be dried for 12 to 24 hours at a temperature of 25 ℃ to 70 ℃. have. In addition, when using the centrifugation method, after removing the supernatant, it can be dried for 12 to 24 hours at a temperature of 25 ℃ to 70 ℃.

In the case of using a fluid replacement method, evaporation or centrifugation can be used simultaneously. That is, after maintaining a large amount of the first and second organic solvents in a wet state by evaporation or centrifugation, an electric insulating oil having a higher breaking point than the first and second organic solvents is added, and a small amount of the first and second organic solvents is added. The organic solvent can be removed completely, and there is no need to proceed with redispersion, and it can be preferably selected. At this time, the isoparaffinic solvent may be used as the electrical insulating oil, but there is no limitation in the configuration thereof, and preferably, the Isopar series supplied from Exxon may be used.

As described above, the types of the surfactants secondary bonded to the polymer main chain and the ionic bond group are designed to show different solubility in the two organic solvents, or additionally, different solubility in the two organic solvents. As long as the polymer main chain and at least one subchain covalently bonded to the main chain are designed, electrophoretic particles having steric hindrance according to the present invention described above can be easily produced.

Alternatively, the steric hindrance according to the present invention can be achieved by simply selecting an appropriate organic solvent having a different solubility for the polymer main chain and the surfactant secondaryly bonded to the ionic bond group, or additionally for the main chain and the sub chain. Electrophoretic particles with) can be produced easily.

In addition, the electrophoretic particles prepared by the above method are exposed at least a part of the surfactant secondary bond to the ionic bond group on the polymer main chain, and / or at least a part of the sub chain covalently bonded to the main chain on the surface of the particle, steric hindrance Due to the steric hindrance, it is expected that the aggregation between the electrophoretic particles can be minimized, resulting in improved image stability and fast response speed when applied to electrophoretic displays.

The electrophoretic particles as described above have a simple manufacturing step, and are easy to manufacture, resulting in less agglomeration between particles, resulting in improved image stability and fast response speed when applied to an electrophoretic display, and thus include electrophoretic particles. It can be usefully used in the industrial field related to the production of electrophoretic display.

1 is a schematic diagram showing a cross section of an electrophoretic particle according to an embodiment of the present invention.
Figure 2 is a schematic diagram showing a cross section of the electrophoretic particles according to another embodiment of the present invention.
Figure 3 is an electron micrograph (FESEM) of the electrophoretic particles according to an embodiment of the present invention.
4 is a schematic diagram briefly illustrating a process of manufacturing an electrophoretic panel according to an embodiment of the present invention.
FIG. 5 is a graph showing measurement results of reflectance and contrast according to voltage of an electrophoretic display according to an embodiment (Example 1) of the present invention. FIG.
Figure 6 shows the measurement by measuring the color coordinate (Lab value) movement according to the voltage of the electrophoretic display according to an embodiment of the present invention (Example 2).
Figure 7 shows the measurement by measuring the color coordinate (Lab value) movement according to the voltage of the electrophoretic display according to an embodiment (Example 3) of the present invention.
FIG. 8 is a diagram illustrating measurement and movement of color coordinates (Lab values) according to voltages of an electrophoretic display according to an embodiment (Example 4) of the present invention.
Figure 9 is a graph showing the measurement results of reflectance and contrast according to the voltage of the electrophoretic display according to an embodiment (Example 5) of the present invention.
FIG. 10 is a graph showing measurement results of reflectance and contrast according to voltage of an electrophoretic display according to Comparative Example (Comparative Example 1). FIG.
11 and 12 are graphs showing bistable measurement values of an electrophoretic display according to one embodiment (Examples 1 and 5, respectively) of the present invention.
13 and 14 are graphs showing bistable measurement values of a conventional electrophoretic display.

Hereinafter, the operation and effects of the invention will be described in more detail with reference to specific examples of the invention. However, these embodiments are only presented as an example of the invention, whereby the scope of the invention is not determined.

< Manufacturing example : Preparation of Electrophoretic Particles>

Manufacturing example  1: melting To condensation  by Cationic  Preparation of Polyester

Cationic dyeable polyesters were prepared by melt condensation described below. A 10 liter glass reactor equipped with a paddle type stirrer and a 20 cm fractional distillation column was used to prepare dimethyl terephthalate (941 g, 4.85 moles), dimethyl isophthalate (970 g, 5 moles) and dimethyl 5-sulfoisophthalate. Sodium salt (44.4 g, 0.15 mol) and 1,2-propylene glycol (1520 g, 20 mol) were packed. Then, 1.4 g of titanium detra-isopropoxide and 5.0 g of IGANOX 1010 (available from Clariant Corporation, East Hanover, NJ) were added as a transesterification catalyst. The reactants were filled at room temperature and purged with argon gas for about 1 hour. The reaction mixture was then heated to 150 ° C. while stirring at 50 rpm to make a uniform melt. The reaction mixture was then heated to 150 ° C. to 200 ° C. for 4 hours with argon gas flowing and maintained at 200 ° C. until about 340 ml of distillate came out.

Thereafter, the reaction mixture was slowly heated to 210 ° C. for 30 minutes and then stirred at 210 ° C. at 50 rpm for 1 hour. Then, the stirring speed was lowered to 20 rpm and the reactor was left for about 1 hour in a vacuum of 0.5 torr. Subsequently, the vacuum was released using argon gas and the reaction was cooled to about 150 ° C. Thereafter, the reaction was poured into a glass plate and cooled to room temperature. About 2050 g of polyester resin was obtained.

The glass transition temperature of the polyester resin thus prepared was 65 ° C., the acid value (KOH value) was 8, the number average molecular weight was 5500, the weight average molecular weight was 11200, and the polydispersity was 1.2. The molecular weight is measured by gel permeation chromatography (GPC) using polystyrene as the standard molecular weight.

Manufacturing example  2 : Cationic  On polyester Disintegrate  Preparation of Covalently Bonded Copolymers

100 g of polyisobutylene succinimide (number average molecular weight 2300 g / mol), 10 g of succinic anhydride, and 5 ml of triethylamine were mixed with 250 ml of ethylene chloride. The reaction proceeded for 5 hours while stirring at 200 ° C. at 70 ° C., and the progress of the reaction was confirmed by TLC (thin layer chromatography). After the reaction was completed, the temperature was slowly lowered to -4 ° C, and unreacted succinic anhydride was removed by filtration while stirring at 10 rpm for 4 hours, and the catalyst was removed using distilled water. Ethylene chloride (Ethylene chloride) solution to remove the saturated distilled water using magnesium sulfate and distilled under reduced pressure to remove ethylene chloride (Ethylene chloride) to obtain a derivative 98g. The structure of the derivative was confirmed using NMR 400 Hz.

The esterification of the derivative and the terminal alcohol functional group of the cationic polyester prepared according to Preparation Example 1 using Dicyclohexylcarbodiimide (DCC) was carried out by the following method. 100 g of the cationic polyester prepared in Preparation Example 1, 90 g of the derivative, and 2 ml of triethylamine were dissolved in 200 ml of methylene chloride, followed by adding DCC 9 g while maintaining the temperature at 30 ° C. for 2 hours. The reaction proceeded. The progress of the reaction was confirmed by the precipitation of dicyclohexylurea (dicyclohexylurea), the overall reaction progress was confirmed by TLC. After the completion of the reaction, the temperature was slowly lowered to -4 ° C and the precipitation of dicyclohexylurea was induced while stirring at 10 rpm for 4 hours, followed by filtration, and the filtrate was added to 1 L of n-hexane. Precipitation of ester and polyisobutylene succinimide conjugates was induced, and unreacted polyisobutylene succinimide derivative dissolved in n-hexane was removed by filtration.

The acid value (KOH) of the copolymer of the polyester polyisobutylene succinimide prepared as described above was found to be 8, the same as that of the polyester before the reaction, and the number average molecular weight of the copolymer was 6500, and weight average. The molecular weight was measured at 16200. Molecular weight was measured by gel permeation chromatography (GPC) using polystyrene as the standard molecular weight.

Manufacturing example  3: Preparation of Electrophoretic Particles

1.60 g of the cationic polyester prepared in Preparation Example 1 was dissolved in 20 ml of methyl ethyl ketone, which is the first organic solvent, and then 0.40 g of carbon black was added, and then bead mill was used. Dispersion was performed at room temperature so that the volume average particle diameter of the carbon black is 70nm to 400nm. Preferably, the dispersion was performed until the volume average particle diameter became 100 nm to 250 nm. (Dispersion 1)

Dispersion 1 was dissolved by adding 0.40 g of Bontron N07 (orient corporation) as a charge control agent. (Dispersion 2)

20 ml of methyl ethyl ketone, which is the first organic solvent, was added to the dispersion 2 to dilute it, and then 0.2 g of hexadecyl trimethyl ammonium bromide was added as a surfactant. Although not observed microscopically or visually, a small amount of polymer association was induced. (Dispersion solution 3) 45 ml of the dispersion solution 3 thus prepared was added to 100 ml / min in a reactor stirred at 100 rpm with 100 ml of n-hexane as a second organic solvent. (Reaction solution 1)

After mixing Isopar G (specific gravity 0.75) or Isopar M and halocarbon oil 1.8 (specific gravity 1.8), which are electrically insulating oils, to a specific gravity of 1.35, 6 ml of the mixed solution is added to the reaction solution 1, at 40 ° C. After distillation under reduced pressure to remove the first organic solvent and the second organic solvent was prepared 8ml of black ink containing a relatively positively charged electrophoretic particles (Preparation Example 3), the concentration was 0.278g / ml.

Meanwhile, only the first organic solvent shown in Table 1 below instead of methylethylketone, and the second organic solvent shown in Table 1 below instead of n-hexane are used, and through the same materials and processes as in Preparation Example 3 above. The ink containing the electrophoretic particles of Preparation Examples 4 to 8 was prepared, and the volume particle size distribution of the prepared electrophoretic particles was measured using Malvern Zetasizer Nano ZS.

No. First organic solvent Second organic solvent Particle size distribution (nm) D10 D50 D90 Production Example 3 MEK ¹ n-Hexane 210 452 717 Preparation Example 4 MEK Isopar g 540 921 1154 Preparation Example 5 MEK Halocarbon oil 0.8 461 1070 1470 Preparation Example 6 Toluene n-Hexane 171 380 611 Preparation Example 7 THF ² n-Hexane 221 410 652 Preparation Example 8 MC ³ n-Hexane 251 542 892

Co., Ltd. 1: Methylethylketone, 2: Tetrahydrofuran, 3: Methylene chloride

Manufacturing example  9 and 10: Preparation of electrophoretic particles with different surfactants

Instead of hexadecyl trimethyl ammonium bromide, except for using the surfactant shown in Table 2 below, the ink containing the electrophoretic particles according to Preparation Examples 9 and 10 was prepared in the same manner as in Preparation Example 3. The type of surfactant used in each preparation example is as shown in Table 2 below, and the volume particle size distribution of the prepared electrophoretic particles was measured using Malvern Zetasizer Nano ZS, and shown in Table 2 below.

No. Surfactants Particle size distribution (nm) D10 D50 D90 Production Example 3 hexadecyl trimethyl ammonium bromide 210 452 717 Preparation Example 9 Oleyl amine 301 502 669 Preparation Example 10 Polyisobutylene succinimide 244 589 692

Manufacturing example  11-15: Preparation of Electrophoretic Particles with Different Surfactant Contents

The electrophoretic particles according to Preparation Examples 11 to 15 were prepared in the same manner as in Preparation Example 3, except that only the content of the surfactant used in Preparation Example 3 was used. The content of hexadecyl trimethyl ammonium bromide, a surfactant used in each preparation example, is shown in Table 3 below. Measured as shown in Table 3 below.

No. Usage of Surfactant Particle size distribution (nm) D10 D50 D90 Production Example 3 0.2 g 210 452 717 Preparation Example 11 0.1g 289 681 992 Production Example 12 0.05g 344 897 1511 Preparation Example 13 0.3 g 201 387 612 Preparation Example 14 0.4g 198 377 612 Preparation Example 15 2.0 g 174 259 420

Manufacturing example  16 to 19: Colorant  Preparation of Different Electrophoretic Particles

Preparation Example 16 in the same manner as in Preparation Example 3 except for using the coloring material and the charge control agent according to Table 4 in place of the carbon black (carbon black) and the charge control agent Bontron N07 used in Preparation Example 3 To electrophoretic particles according to Preparation Example 19 were prepared. The volume particle size distribution was measured using Malvern Zetasizer Nano ZS and is shown in Table 4 below.

No. Color material type content Charge control agent Particle size distribution (nm) D10 D50 D90 Production Example 3 Carbon black ¹ 0.4g Bontron n07 210 452 717 Production Example 16 Blue pigment ² 0.25g Bontron p51 341 611 817 Production Example 17 Magenta Pigment ³ 0.45 g Bontron p51 491 784 912 Production Example 18 Yellow Pigment ⁴ 0.45 g Bontron p51 202 412 612 Production Example 19 White pigment ⁵ 0.8 g Bontron e88 239 342 568

1: Regal 330R (Cabot corporation)

2: C. I. Pigment Blue 15: 3, Color Index (CI) No.74160 (Japan Ink Corporation (DIC))

3: Red 122 (Japan ink company (DIC))

4: Yellow HG (Clariant)

5: R104 (Dupont)

Manufacturing example  20 and 21: Preparation of electrophoretic particles using a copolymer

1.0 g of the polyester of Preparation Example 1 and 0.6 g of the copolymer of Preparation Example 2 were dissolved in 20 ml of methyl ethyl ketone, which is the first organic solvent, and then 0.40 g of carbon black was added as a colorant. Dispersion was performed using a wheat mill. Dispersion was carried out so that the volume average particle diameter of the carbon black was 70 nm to 400 nm, and preferably dispersed until it became 100 nm to 250 nm.

Dispersion 1 was dissolved by adding 0.40 g of Bontron N07 (orient corporation) as a charge control agent (dispersion 2).

After diluting by adding 20 ml of Methylethylketone, which is the first organic solvent, to the dispersion 2, 0.2 g of hexadecyl trimethyl ammonium bromide was added as a surfactant. Although not observed microscopically or visually, a small amount of polymer association was induced. (Dispersion 3) 45 ml of the dispersion 3 thus prepared was added to 100 ml of n-hexane and added to the reactor under stirring at 100 rpm at 100 ml / min. Reaction solution 1)

Isopar G (specific gravity 0.75) or Isopar M and halocarbon oil 1.8 (specific gravity 1.8), which are electrically insulating oils, were mixed with the specific liquid to 1.35. By distillation to remove the first organic solvent and the second organic solvent was prepared 8ml of black ink containing a relatively positively charged electrophoretic particles (Production Example 20), the concentration was found to be 0.269g / ml, volume average The particle size was 543 nm.

On the other hand, except that the color material was prepared by using 0.8 g of titanium oxide R104, 0.2 g of Bontron E88 as a charge control agent, and the electrophoretic particles (preparation 21) having a relatively negative charge through the same process as in Preparation Example 20. 8 ml of a white ink was prepared, and the concentration was 0.325 g / ml, and the volume average particle diameter was 381 nm. Volume particle size distribution was measured using Malvern Zetasizer Nano ZS.

< Example > In manufacture example  Electrophoretic display including electrophoretic particles

Example  One

Using KORON KS-8700 DFR (photosensitive film) on glass coated with ITO transparent electrode, barrier ribs are formed through lamination, exposure and development processes, and black ink containing electrophoretic particles exhibiting positive charges in Preparation Example 3 A white ink containing negatively charged electrophoretic particles of Example 19 was mixed in a volume ratio of 1:10, and then injected into a partition wall, covered with a glass coated with an ITO transparent electrode, and a UV adhesive (DHUV-7301, Glue-Tech adhesive). The exterior was closed using. A process for producing an electrophoretic panel with an ink containing electrophoretic particles is briefly shown in FIG. 4.

The electrophoretic panel was prepared as described above, and the reflectance and contrast ratio (contrast) according to the voltage of the electrophoretic display including the panel were measured by using a luminance measuring device (SpectraDuo PR-680). 5 shows a graph of measurement results of reflectance and contrast according to the voltage.

As shown in FIG. 5, the electrophoretic display according to Example 1 exhibits a white maximum reflectance of about 45% and a black minimum reflectance of 4.5%, and a contrast ratio of about 10: 1, which is equivalent to that of a conventional commercially available e-book product. It can be seen that the above excellent characteristics are exhibited.

Example  2

A partition wall was formed as in Example 1, and a blue ink containing positively electrophoretic particles of Preparation Example 16 and a white ink containing negatively electrophoretic particles of Preparation Example 19 were mixed at a volume ratio of 1:10. Injected into the partition wall, covered with a glass coated with an ITO transparent electrode and the outside was sealed using a UV adhesive (DHUV-7301, Glue-Tech adhesive).

An electrophoretic panel was prepared as described above, and color coordinate (Lab values) shifting according to voltage of an electrophoretic display including such a panel was measured using a luminance measuring device (SpectraDuo PR-680). The change in color coordinates according to the measured voltage is shown in FIG. 6. As shown in FIG. 6, the electrophoretic display according to Example 2 is easily switched within an applied voltage of ± 15 V in switching between a blue state and a white state, and an intermediate color representation is obtained. It was possible to find out.

Example  3

A partition wall was formed as in Example 1, followed by mixing the magenta ink containing the positively charged electrophoretic particles of Preparation Example 17 and the white ink containing the negatively charged electrophoretic particles of Preparation Example 19 in a volume ratio of 1:10. Was injected into the glass, which was covered with a glass coated with an ITO transparent electrode, and the outside was sealed using a UV adhesive (DHUV-7301, Glue-Tech adhesive).

An electrophoretic panel was prepared as described above, and color coordinate (Lab values) shifting according to the voltage of the electrophoretic display was measured using a luminance measuring device (SpectraDuo PR-680). The change in color coordinates according to the measured voltage is shown in FIG. 7. As shown in FIG. 7, the electrophoretic display according to Example 3 is easily switched within an applied voltage of ± 15 V in switching between a magenta state and a white state, and an intermediate color representation is obtained. It was possible to find out.

Example  4

A partition wall was formed as in Example 1, and the partition wall was mixed with a yellow ink containing positively charged electrophoretic particles of Preparation Example 18 and a white ink containing negatively electrophoretic particles of Preparation Example 19 at a volume ratio of 1:10. Was injected into the glass, which was covered with a glass coated with an ITO transparent electrode, and the outside was sealed using a UV adhesive (DHUV-7301, Glue-Tech adhesive).

An electrophoretic panel was manufactured as described above, and color coordinate (Lab values) shifting according to the voltage of the electrophoretic display was measured using a luminance measuring device (SpectraDuo PR-680). The color coordinate change according to the voltage is shown in FIG. 8. As shown in FIG. 8, the electrophoretic display according to Example 4 is sufficiently easy to switch within an applied voltage of ± 15 V in switching between a yellow state and a white state, and an intermediate color representation is obtained. It was possible to find out.

Example  5

A partition wall was formed as in Example 1, mixed with a black ink containing positively electrophoretic particles of Preparation Example 20 and a white ink containing electrophoretic particles of Preparation Example 19, having a relatively negative charge, in a volume ratio of 1:10. After the injection into the septum, it was covered with a glass coated with an ITO transparent electrode and the outside was sealed using a UV adhesive (DHUV-7301, Glue-Tech adhesive).

The electrophoretic panel was prepared as described above, and the reflectance and contrast ratio (contrast) according to the voltage of the electrophoretic display were measured using a luminance measuring device (SpectraDuo PR-680). The measurement results of reflectance and contrast according to the voltage are shown in FIG. 9. As shown in FIG. 9, the electrophoretic display according to Example 5 exhibits a white maximum reflectance of about 45% and a black minimum reflectance of about 4.5%, wherein the contrast ratio is equal to or greater than that of a conventional e-book product commercially available at about 10: 1. It can be seen that the characteristics.

< Comparative example Preparation of Electrophoretic Displays Containing Conventional Electrophoretic Particles

Comparative example  One

The reflectance and contrast ratio (contrast) according to the voltage of Sipix's electrophoretic display were measured using a luminance measuring instrument (SpectraDuo PR-680). The measurement results of reflectance and contrast according to the voltage are shown in FIG. 10. As shown in FIG. 10, the electrophoretic display according to Comparative Example 1 had a maximum white reflectivity of about 26%, a minimum black reflectance of about 4%, and a contrast ratio of about 6.5: 1. The electrophoretic display according to Comparative Example 1 was found to have a lower contrast value than the electrophoretic display according to the embodiments of the present disclosure.

Comparative example  2

The reflectance and contrast (contrast) of the black display unit and white display unit of the Amazon e-book kindle 2 including the electrophoretic display unit of E-ink were measured using a luminance measuring device (SpectraDuo PR-680), and the black reflectance was 4.8. ~ 6.2%, white reflectance was found to be 41.1 ~ 44.2%, the contrast was confirmed that the value (contrast ratio) is about 7: 1.

< Experimental Example >

In addition, the properties of the electrophoretic particles according to the above-described manufacturing examples and the performance of the electrophoretic display according to the above-described examples and comparative examples were tested in the following manner.

One. Manufacturing examples  Properties of electrophoretic particles

1) Image analysis of electrophoretic particles

The nanoparticle shape was observed using a FESEM field scanning electron microscope (JSM 890, JEOL LTD). Representatively, the FESEM image of the electrophoretic particles according to Preparation Example 20 is shown in FIG. 3.

2) Measurement of particle size and particle size distribution of electrophoretic particles

The electrophoretic particles were dispersed at a concentration of 0.01 g / ml in Isopar G as a dispersion medium, and the volume particle size distribution was measured using Zetasizer Nano ZS (Malvern) at 25 ° C. In using the Zetasizer Nano ZS, the electrophoretic particles and the reflective index of Isopar G were input, and the measurement angle was set to 173 ° Backscatter.

2. Example  And In the comparative examples  Properties of electrophoretic displays

1) Reflectance Measurement by Voltage

The reflectance of the standard white reflector (SRS-3, Photo Research) is set to 100% while maintaining the angle of the luminance measuring equipment (SpectraDuo PR-680), the light source (Halogen lamp) and the sample holder inside the dark room at 45 degrees. After setting the reference, the reflectance and color coordinates of the standard white reflector at each voltage were measured while applying a voltage to the measurement sample with a power supply (EEC-P640, ELPSA).

2) Bistable ( bistability ) Measure

Using the power supply (EEC-P640, ELPSA), -10V was applied for 500ms to switch to the black state, the power supply was stopped, and the bi-stability of the black state was measured by measuring the reflectance over time. The bistable stability of the white state was measured by applying a voltage to the white state, turning off the power supply, and measuring the reflectance over time.

Measurements of the bistable stability of the electrophoretic displays according to Example 1 and Example 5 are shown in FIGS. 11 and 12, respectively. On the other hand, it was shown in Figure 13 and 14, respectively, to measure the bi-stability of the electrophoretic display according to Comparative Example 1 and Comparative Example 2.

As can be seen from the measurement results of reflectance and contrast according to the voltage of the electrophoretic display according to the above-described embodiments and comparative examples, the electrophoretic display according to the present embodiment has a maximum white reflectance value of about 45%. On the other hand, the electrophoretic display according to the comparative example had a maximum white reflectance value of about 26%, which was lower than the maximum white reflectivity value of the electrophoretic display according to the embodiment. This indicates that the electrophoretic display according to an embodiment of the present invention is excellent in display visibility, and in particular, it can be expected that color realization and color reproducibility using a color filter are excellent.

In addition, as can be seen from the result of the color coordinate shift according to the voltage of the electrophoretic display according to the embodiments of the present invention shown in FIGS. 6 to 8, the electrophoretic display according to the above-described embodiments uses respective color particle inks. Therefore, when the color filter is used to implement a color display, it may appear brighter and have excellent color reproduction.

And, as shown in Figures 11 to 14, it was confirmed that the electrophoretic display according to the embodiment of the present application exhibits equal or more than the bistable stability compared to the comparative example.

100: electrophoretic particles
12, 19: polymer backbone
16: ion coupler
18: disintegration
20: color material
30: charge control agent
40: surfactant
50: stereoscopic obstacle

Claims (23)

In electrophoretic particles,
A binder resin comprising a polymer main chain and at least one ionic bond group bonded to the polymer main chain, wherein the polymer main chain has a particle shape;
A color material dispersed in the binder resin;
A charge control agent dispersed in the binder resin; And
It comprises a surfactant secondary bonded to the ion bond group,
At least a portion of the surfactant secondary bonded to the ion bonder of the polymer backbone is exposed to the surface of the electrophoretic particles, and at least a portion of the surfactant exposed to the surface of the electrophoretic particles is steric hindrance between the electrophoretic particles ( Electrophoretic particles with steric hindrance. The method of claim 1, wherein the binder resin further comprises one or more subchains covalently bonded to the polymer backbone, at least a portion of the subchains are exposed to the surface of the particles, the ionic bond covalently bonded to the polymer backbone Electrophoretic particles. The electrophoretic particle of claim 1, wherein the binder resin includes a plurality of polymer backbones, the plurality of polymer backbones includes one or more subchains covalently bonded thereto, and the plurality of polymer backbones have a particle shape. The method of claim 1,
Wherein said secondary bond comprises at least one of ion to ion bond, dipole to dipole bond, van der Waals bond, and ion to dipole bond. delete delete delete delete In electrophoretic particles,
A binder resin comprising a polymer main chain and at least one ionic bond group bonded to the polymer main chain, wherein the polymer main chain has a particle shape;
A color material dispersed in the binder resin;
A charge control agent dispersed in the binder resin; And
It comprises a surfactant secondary bonded to the ion bond group,
At least a portion of the surfactant secondary bonded to the ionic bond group of the polymer backbone is exposed to the surface of the electrophoretic particles,
The polymer backbone is electrophoresis comprising at least one repeating unit selected from the group consisting of polyester, polyamide, polyurethane, polyacrylate, and polystyrene. particle. The method of claim 2,
The ion bonding group includes an acid group of a carboxyl group, a sulfonic acid group, a phosphoric acid group, a sulfate group and a sulfonate group; Base groups of amine groups, ammonium groups, and imine groups; And electrophoretic particles of at least one functional group selected from the group consisting of sodium sulfonate, potassium sulfonate, sodium phosphate, potassium phosphate, and amine salts. The method of claim 3, wherein
The sub chain is at least one repeating unit selected from the group consisting of isobutylene, hexyl methacrylate (hexylmethacryalte), laurylmethacrylate, methyl methacrylate and styrene Including,
The polymer backbone includes an electric material including at least one repeating unit selected from the group consisting of polyester, polyamide, polyurethane, acrylic ester, and urethane ester. Electrophoretic particles. The method of claim 1, wherein the color material is
Blue pigments, red pigments, green pigments, cyan pigments, magenta pigments, yellow pigments, black pigments, white pigments; And at least one electrophoretic particle selected from the group consisting of cationic dyes, anionic dyes, and dyes of disperse dyes. The method of claim 1,
The charge control agent is an electrophoretic particle which is a positive charge control agent, a negative charge control agent or a mixture thereof. The method of claim 1,
The surfactant is at least one cationic surfactant selected from the group consisting of amine salts and alkyl ammonium; at least one anionic surfactant selected from the group consisting of α-olefin sulfonates, alkyl sulfate ester salts, alkyl ether sulfates, and alkyl sulfonates; Or electrophoretic particles which are at least one nonionic surfactant selected from the group consisting of polyisobutylene succinimide and polyoxyethylene lauryl ether. The electrophoretic particle of claim 1, wherein the volume average particle diameter is 50 to 3000 nm. In electrophoretic particles,
A binder resin comprising a polymer main chain and at least one ionic bond group bonded to the polymer main chain, wherein the polymer main chain has a particle shape;
A color material dispersed in the binder resin;
A charge control agent dispersed in the binder resin;
Surfactant secondary bonded to the ion bond group; And
The binder resin further includes at least one sub chain covalently bonded to the polymer main chain and exposed to the surface of the particles,
At least a portion of the surfactant secondary bonded to the ionic bond group of the polymer backbone is exposed to the surface of the electrophoretic particles,
The surfactant or the sub chain is electrophoretic particles are exposed to the surface of the electrophoretic particles by a number average molecular weight of 500g to 10,000g per mole of the electrophoretic particles. delete delete An electrophoretic medium comprising one or more of the electrophoretic particles of any one of claims 1 to 3 and 9 to 16 dispersed in an insulating fluid. 20. The electrophoretic medium of claim 19, further comprising a capsule containing the electrophoretic particles dispersed in the insulating medium. The method of claim 19,
The insulating medium is an aliphatic hydrocarbon or an electrophoretic medium that is a mixture of a halogenated hydrocarbon and an aliphatic hydrocarbon. An electrophoretic display comprising a pair of electrodes comprising at least one transparent electrode and an electrophoretic medium according to claim 19 between the electrodes. 23. An electrophoretic display according to claim 22 for use in display devices of portable computers, electronic books, mobile phones, smart cards, advertising displays or watches.

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