KR20050054794A - Slurry compositions of charged color particle and preparing method thereof for electrophoretic display - Google Patents

Abstract

The present invention relates to colored charged particle slurry compositions suitable for electrophoretic displays and methods for their preparation. More specifically, the present invention relates to a non-capsulated colored charged particle slurry composition for electrophoretic displays composed of an inorganic oxide, an amine-based silane coupling agent, a dispersant, a suspension fluid, an ionic donor, and an anionic organic dye, and a method for preparing the same. The colored charged particle slurry according to the present invention allows good dispersion between colored particles by the repulsive force between ions, and unlike the conventional microcapsule type particles, the colored charged particle slurry according to the present invention is simple as a non-encapsulated colored charged particle. And the stability was excellent. In addition, the present invention enables the production of red, blue, and green charged particles, which are not only white and black, but also three primary colors of light, thereby making it possible to produce full color or area color electrophoretic displays.

Description

Colored charged particle slurry composition for electrophoretic display and preparation method thereof {Slurry compositions of charged color particle and preparing method about for electrophoretic display}

In general, modern information display devices such as liquid crystal displays (LCDs) and plasma display panels (PDPs) are heavier than conventional papers, are easily fatigued, and are not bendable. I still prefer to see through paper rather than. However, modern displays have the advantage of being able to read and write repeatedly, which can compensate for the shortcomings of paper in terms of recycling resources. Therefore, there is a need for a new type of display device having the advantages of paper but having the function of a modern display. The new display, called electrophoretic display or e-Paper display, is considered a display that combines the advantages of paper and modern displays.

1A and 1B are explanatory views of driving a conventional electrophoretic display, in which a microcapsule 20 is positioned between the first and second two electrodes 10 and 11, and the microcapsule 20 is positive. The first dye particles 21 having a positive charge and the second dye particles 22 having a negative charge are included in fluid. Therefore, as shown in FIGS. 1A and 1B, when a forward or reverse voltage (FIGS. 1A and 1B) is applied to the first and second electrodes 10 and 11 from the power sources 51 and 52, the microcapsule ( The first dye particles 21 having a + charge and the second dye particles 22 having a − charge are moved in accordance with the polarity of the applied voltage, thereby obtaining a display displaying a character or a picture in real time. have.

When the microcapsules are arranged on a polymer matrix to produce an electrophoretic display panel, the white particles having a (+) or (-) charge in the microcapsule (typically TiO ₂ white pigment) are described. As they gather up or down depending on the formation of the electric field, the observer's field of view can sense the color difference of the pixels corresponding to each microcapsule, thus acting as a display.

The paper of the microcapsule type electrophoresis method is known to be the brightest display screen among a variety of driving methods and is known to be the most suitable for implementing a high resolution has attracted a lot of attention. One of the key technologies in this approach is the microcapsule that encapsulates the internal particles, and many research institutes are developing charged particle materials that will fit inside the capsules, with particular emphasis on developing materials suitable for color realization. Organic pigments are more suitable than inorganic pigments in terms of various color characteristics, but organic dyes have a problem in that they are more difficult in terms of driving, that is, electrophoresis than inorganic pigments. In addition, the presently developed microcapsule type electrophoretic e-paper is still insufficient to meet the requirements as a display. This is suitable for bright screen implementation, but the voltage of particle driving inside the capsule is relatively high, afterimage phenomenon occurs due to slow response speed, and there are still problems in high resolution and color implementation. In the case of charged particles, it has an important effect on electrophoresis such as particle size, density, and charge. The particle size is available in the range of 1 nm to 100 μm, but the electrophoresis is as small as possible and the electrophoresis is 10 ^-4 to 10 ^-5 cm. It is required to be ² / V · sec or more.

The present inventors have found the following problems as a result of preparing and evaluating the pigment particles for electrophoretic display by the method described in the prior art (U.S. Patent 6,017,584 and U.S. Patent 6,120,588). Particles for electrophoretic displays according to the prior art are mainly contained within the microcapsules, which may be prepared through the process of preparing an oil phase, preparing an aqueous phase, and encapsulation. In addition, the manufacturing method and conditions of such a microcapsule are difficult, and the microcapsule type has a problem in that the stability of the final particles is low, thereby decreasing the degree of aggregation or electrophoresis. Under these circumstances, a new method for producing colored charged particles having a simple concept of producing colored charged particles for electrophoretic displays and excellent stability of the finally prepared colored charged particles was required.

The present invention is designed to solve the problems of microcapsule-type particle production as described above, and has a feature of non-capsule type unlike the prior art, and provides electrophoretic colored charged particle compositions of various colors and a method of manufacturing the same. There is a purpose. That is, to provide a non-capsule-type charged particle composition having a color size and electrophoresis suitable for electrophoresis and a method for producing colored charged particles. In the present invention, a silane coupling agent having an amine group is introduced to impart a charge to the surface of the inorganic particles, and the amine group of the silane coupling agent is reacted with an ionizing agent to form quaternized cations. By reacting a part of with an anionic organic dye, a new fact that the production of non-encapsulated colored charged particles of a desired color is possible and the present invention has been completed.

The present invention relates to an electrophoretic colored charged particle composition and a method of manufacturing the same, which enables full color or area color electrophoretic display to be implemented, and to a non-capsule type for solving the above technical problem. A new colored charged particle slurry composition and a method of preparing the same are provided. According to an aspect of the present invention for solving the above technical problem is provided an electrophoretic non-capsule-type colored charged particle slurry composition, inorganic oxide 0.1 to 15% by weight, dispersant 0.05 to 7% by weight, amine-based silane coupling agent It is characterized by consisting of 0.1 to 15% by weight, 40 to 99% by weight of suspension fluid, 0.05 to 7% by weight of ionizer, 0 to 15% by weight of anionic organic dye.

According to another aspect of the present invention, the inorganic oxide, the dispersant, and the amine-based silane coupling agent are added to the suspension fluid to disperse and simultaneously introduce an amine group on the surface of the inorganic oxide particle, and to add an ionic emulsifier to the inorganic oxide The second step of forming a cation by reacting with the amine groups introduced to the particle surface, and 5 to 95 mol% of anionic organic dye compared to the amine silane coupling agent of the first step is added to the cation of the inorganic oxide particle surface Provided is a method for producing non-encapsulated colored charged particles for electrophoretic displays, which is prepared by a third step of introducing an organic dye into an inorganic oxide by ion-bonding with an ion.

Hereinafter, the present invention will be described in detail through a non-capsule-type colored charged particle composition of the present invention and its preparation process in order to enable those skilled in the art to more easily carry out the present invention. .

In the method for preparing non-encapsulated colored charged particles of the present invention, the first step is first adding an inorganic oxide of several hundreds to several hundreds of nm to a suspension fluid, and then pulverizing the aggregated inorganic oxide by sonication for 10 to 30 minutes, followed by amine It consists of adding a silane coupling agent and a dispersant for dispersion stability and stirring or milling for 1 to 24 hours. In the stirring or milling process, the hydroxyl group (-OH group) present on the surface of the inorganic oxide and the alkoxysilyl group (RO-Si-) of the amine silane coupling agent react to introduce the amine group to the surface of the inorganic oxide. That is, particles in the form of an inorganic oxide-O-Si-amine group are formed. In addition, the dispersant disperses the inorganic oxide particles into which the amine group is introduced, in the suspension fluid, and minimizes the precipitation of the particles.

The inorganic oxide of the present invention may have a size of several hundreds to several hundred nm, and may be any material including a hydroxyl group on the surface of the particle, and may include TiO ₂ , SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , CuO, In ₂ O ₃ , ZnO, SiMnO ₄ , PbO, B ₂ O ₃ , MgO, RuO, NiO, Cr ₂ O ₃ , BaCO ₃ , ZrO ₂ , MgCO ₃ , BaO, Bi ₂ O ₃ , and the like. There are many. In the case of not having a hydroxyl group on the surface of the inorganic oxide particle, a hydroxyl group may be artificially formed. In this method, the hydroxyl group may be introduced to the surface of the inorganic oxide by plasma treatment in the presence of hydrogen, oxygen, moisture or air.

In addition, the suspending fluid of the present invention is suitable for a material having a dielectric constant, high volume resistivity, low viscosity, low toxicity, high specific gravity, high boiling point and low reflection index in the range of 1 to 15, and cyclohexanone ), Tetrachloroethane, methylenechloride, ethanol, toluene, xylene, chlorotrifluoroethylene, dodecylbenzene, penta Chlorobenzene (pentachlorobenzene) and the like. The suspension fluid of the present invention may be colored (suspension fluid colorant) to dyes or pigments, nonionic azo dyes, anthraquinone blue, solvent blue 35, solvent blue 37, oil blue N, solvent green series, solvent orange series, Solvent red series, solvent yellow series and the like can be used. The amine silane coupling agent of the present invention is an alkoxysilyl group [(RO) H ₂ Si-, (RO) ₂ HSi-, (RO) ₃ Si-] and an amine group (- NH ₂ , -NRH, -NR ₂ ) may be used at the same time, aminopropyltriethoxysilane (aminopropyltriethoxysilane), aminopropyltrimethoxy silane (aminopropyltrimthoxy silane), aminopropyl methyl diethoxysilane (aminopropyl methyldiethoxysilane), Aminopropylmethyl dimethoxysilane, aminoethylaminopropyl trimethoxysilane, aminoethylaminopropyl triethoxysilane, aminoethylaminopropylmethyldimethoxysilane, Diethylenetriaminopropyltrimethoxysilane, diethylenetriaminopropyltriethoxysilane ( diethylenetriaminopropyltriethoxy silane), diethylenetriaminopropylmethyldimethoxysilane, diethylenetriaminopropylmethyldiethoxysilane, and the like.

Dispersants added for the purpose of stabilizing dispersion and minimizing sedimentation of inorganic oxide particles are BYK-192, BYK-190, BYK-Chemie, Span 20, Span 40, Span 60, Span 80, Span 85, Tween 20, Examples include Tween 40, Tween 60, and Tween 80. The present inventors devised a method for dispersing the colored charged particles by another method (dispersant of the combined type) in addition to the method of using the additive type dispersant as described above, and the contents are as follows. same. In the step of dispersing the inorganic oxide, which is the first step of the method for producing colored charged particles, in a suspension fluid and adding or stirring an amine silane coupling agent and a dispersing agent, an alkyl group having 5 or more carbon atoms is used as the dispersant. Using a nonpolar silane coupling agent having a non-polar silane coupling agent is introduced on the surface of the inorganic oxide (the same principle as the introduction of the amine-based silane coupling agent) and the dispersion effect can be obtained by maintaining a certain distance between the inorganic oxide by the steric hindrance effect of the long alkyl group It was confirmed that there is. Such nonpolar silane coupling agents include n-octyltriethoxy silane, n-octadecyl triethoxy silane, n-pentyltrimethoxy silane, n-dodecyltrimethoxy silane, n-hexyltriethoxy silane, n-hexadecylmethoxy silane, for example, there are many kinds.

As described above, the liquid in the form of a slurry containing an inorganic oxide, a suspension fluid, a silane coupling agent, and a dispersant is subjected to stirring or milling for 1 to 24 hours in order to proceed with dispersion and reaction, and to improve milling effect, zirconia beads ( zirconia bead).

In the method for preparing a non-encapsulated colored charged particle of the present invention, the second step is to quaternize the amine group introduced to the surface of the inorganic oxide by the first step to cationize the slurry, in which the first step is completed. An ionizing agent is added to the liquid to form a cation by an acid group reaction. The ionizing agent of the present invention may be any substance capable of quaternization by reacting with an amine group, and an alkyl halide such as bromoethane, bromobutane, crorobutane, and chloropropane, benzyl bromide, benzyl chloride and dimethyl Sulfate, benzene sulfonic acid, toluene sulfonic acid, acetic acid, etc. are mentioned, There are many examples. As described above, quaternization of the amine group introduced on the surface of the inorganic oxide with the ion-imparting agent enables the introduction of cations on the surface of the inorganic oxide.

In the method for preparing non-encapsulated colored charged particles of the present invention, the third step is to impart a color by reacting a cation on the surface of the inorganic oxide prepared by the second step with an anionic organic dye. In the first and second steps, cations could be imparted to the surface of the inorganic oxide, and these cations could be ion-bonded with the anion component. Thus, when an anionic organic dye having various colors is added and reacted, the cation-anion ion bond This is done to be able to introduce the organic dye on the inorganic oxide surface. At this time, care should be taken to control the use of anionic organic dyes, since the cations introduced by the first and second stages play the role of introducing the organic dyes in the third stage and at the same time giving the electrophoresis. Is essential. That is, the anionic organic dye reacts with the cation on the surface of the inorganic oxide and loses its ionicity. In this case, the electrophoretic property may be lost (FIG. 2A). Therefore, the number of anionic organic dyes to be introduced must be less than the number of cations present on the surface of the inorganic oxide, and must include a portion present in the form of a cation without reacting with the anionic organic dye (Fig. 2b). This cation is effective in improving particle dispersibility by inducing repulsion between colored charged particles. Anionic with an organic dye of the present invention dawn (-COO ^-) in acetic Te that can be the cation and an ionic bond, a sulfonate group (-SO ₃ ^-) is possible if organic dyes having, as the red dye is Acid Red (acid red) acid red 1, 4, 8, 14, 17, 18, 26, 27 and 29 and the like, as a blue dye acid blue (acid blue) acid blue 1, 7, and the like. 9, 25, 29, 40, 45, 74 and the like, and the green dye is an acid green (acid green) acid green 1, 3, 5, 25, 27 and 50 and the like, for example, Examples of the black dye include acid black based acid black 1, 2, 24 and 48, and purple dyes include acid violet based acid biolet 7, 9, 17 and 19. Examples of the orange dye include acid orange 6, 7, 8, 10, 12, 51, 52, 63 and 74 acidic orange. The yellow salts may include acid yellow based acid yellows 1, 3, 9, 11, 17, 23, and 25, and numerous other examples.

As described above, non-capsulated colored charged particles exhibiting color while exhibiting electrophoresis were prepared by the first, second and third steps, and injected into a panel for an electrophoretic display composed of a cathode and an anode. When the electric field is applied, the inorganic oxide having the cation and the organic dye is moved to the cathode and positioned on the cathode surface, thereby enabling the implementation of a color electrophoretic display.

The non-capsulated colored charged particle slurry for electrophoretic display obtained by the above process is 0.1 to 15% by weight of inorganic oxide, 0.05 to 7% by weight of dispersant, 0.1 to 15% by weight of amine silane coupling agent, 40 to 99% by weight of suspension fluid, It is characterized by consisting of 0.05 to 7% by weight ionizer, 0 to 15% by weight of anionic organic dyes. In particular, the anionic organic dye is 5 ~ 95 mol (mol)% is suitable compared to the amine-based silane coupling agent, the purity of the color is less than 5 mol% and the number of cations on the surface of the inorganic oxide is less than 95 mol% electrophoresis There exists a tendency for dynamics to fall. In addition, the ionizing agent is preferably 10 to 300 mol% compared to the amine-based silane coupling agent, the number of cations is less than 10 mol%, there is a problem that the electrophoresis is lowered, the excess of the ionizing agent is more than 300 mol% impurities Will cause problems.

The present inventors have conducted research based on the basic concept described above to complete the non-encapsulated colored charged particle slurry composition of the present invention and a method for manufacturing the same. It was also possible to implement the transferees.

In the present invention, when TiO ₂ is used as the inorganic oxide, since TiO ₂ itself represents white, it is possible to prepare white charged particles only in the first and second steps of the method for preparing non-capsulated colored charged particles of the present invention. That is, the TiO ₂ powder was mixed and milled together with the suspension fluid, the amine silane coupling agent, and the dispersant to introduce an amine group on the TiO ₂ surface, and an ionizing agent was added thereto to form a cation. This was injected into an electrophoretic display panel having two electrodes and an electric field was applied. As a result, TiO ₂ was electrophoresed and moved to the cathode surface.

In addition, in the method for preparing non-encapsulated colored charged particles of the present invention, all materials (inorganic oxides, amine-based silane coupling agents, dispersants, suspension fluids, and ion-imparting agents) used in the first, second and third step processes It is confirmed that the electrophoretic properties of the finally obtained colored charged particle slurry are the same as those prepared by the above-described first, second and third steps, even when mixed and stirred or milled at a time without adding stepwise, anionic organic dyes). .

In addition, the inorganic oxide of the present invention is advantageous as it does not have a color itself. Because in order to maintain the unique color of the anionic organic dye used in the third step, there should be no inorganic oxide color itself, and if the inorganic oxide itself has a color, the final electrophoretic display will show the color of the inorganic oxide particles and the organic dye. Will implement a second color with a mixed color of. As a result of the present inventors verifying the inorganic oxide, it was confirmed that when SiO ₂ was used as the inorganic oxide, the color of the anionic organic dye could be realized as it was colorless and transparent.

As described above, the method of preparing the present invention was introduced through the method of preparing the non-encapsulated colored charged particles of the present invention, and important features were also introduced. Non-encapsulated colored charged particles could be prepared by a new method that was not known, and their electrophoretic properties were evaluated to confirm that they were operated at a low voltage of 25V or less. Low voltage drive (electrophoresis) of the non-encapsulated colored charged particle slurry of the present invention can be seen as indirect evidence that the charge density of the slurry is improved. Since it has a dispersion effect by the dispersant and the repulsive force between the cations introduced on the surface of the inorganic oxide at the same time maintains a very excellent dispersion state, it can be estimated that the mobility due to the excellent dispersion state between particles appeared.

EXAMPLES The present invention will be described below in detail with reference to Examples of the present invention, but the present invention is not limited to the following Examples.

<Example 1>

As a suspension fluid, 1.0 g of inorganic oxide TiO ₂ was added to 50 g of cyclohexanone and sonicated for 10 minutes to pulverize the aggregated TiO ₂ particles. Next, 1.0 g of 2- (aminoethyl) -3-aminoethylmethyldimethoxysilane [2- (amino ethyl) -3-aminoethylmethyl dimethoxysilane] which is an amine silane coupling agent and an additive dispersant BYK-192 (BYK-chemie) 0.5 g was added followed by milling for 2 hours to introduce an amine group to the TiO ₂ particle surface (first step). At this time, in order to improve the milling effect, the mixture contains zirconia beads (zirconia bead) of 0.4 to 0.5 mm in size, and a pot mill was used as a milling equipment. After milling was completed, acetic acid was added as an ionizer to quaternize the amine groups introduced on the surface of the TiO ₂ particles to generate cations (second step). Solvent Blue 35 (0.5 g) was then added as a suspension fluid colorant to color the background color of the finally obtained white charged particle slurry in blue. In the above method, a slurry was prepared in which the ground color was blue and the charged particles were white, and the zeta potential value of the dispersed charged particles was about +76 mV of positive charge (+ value means positive charge,-value is negative). The mean particle size of the charged particles is 280 nm, the distribution of which is shown in FIG. 3. The above non-encapsulated white charged particle slurry was injected into the electrophoretic display panel in which the negative electrode and the positive electrode faced, and a DC electric field was applied to confirm that the white charged particle was moved to the surface of the negative electrode by electrophoresis. It was 10V and showed the maximum contrast ratio at 30V. Figure 4 shows the luminance graph according to the voltage application of the electrophoretic display produced using the white charged particles obtained in Example 1. Figures 5a and 5b is a photograph of the electrophoretic display produced using the electrophoretic white charged particle slurry prepared in Example 1. 5A is a state before applying an electric field, and FIG. 5B is a photograph of a state in which blue charged particles move to the cathode by electrophoresis and are attached to the cathode surface when a 21 V DC electric field is applied. As shown in FIGS. 5A and 5B, since the solvent blue 35 is dissolved, the ground color is blue, and the particles moved to the cathode by electrophoresis are white (TiO ₂ ).

<Example 2>

As a suspension fluid, 1.0 g of inorganic oxide SiO ₂ particles were added to 50 g of ethanol, followed by sonication for 10 minutes to pulverize the aggregated SiO ₂ particles. Next, the amine-based silane coupling agent 3-aminopropyl silane on (3-aminopropyl triethoxysilane) 1.0 g dispersant and coupled n-octyl triethoxy silane 0.5 g of SiO ₂ particle surface was stirred at 30 ℃ 1.5 hours after adding An amine group was introduced (first step). Then, 0.6 g of dimethylsulfate was added dropwise as an ionic donor to quaternize the amine group introduced on the surface of the SiO ₂ particle (second step) to give a positive charge. 1.0 g of acid red 4, a dye, was added to react with a cation introduced on the surface of SiO ₂ particles and an anion (-SO ₃ ⁻ ) of acid red 4 to prepare an uncapsulated red charged particle slurry. The above red charged particle slurry was injected into the electrophoretic display panel in which the cathode and the anode faced each other, and a DC electric field was applied to confirm that the red charged particles were moved to the surface of the cathode by electrophoresis. appear.

<Example 3>

As a suspension fluid, 1.0 g of inorganic oxide SiO ₂ particles were added to 50 g of methylene chloride, and ultrasonically treated for 10 minutes to pulverize the aggregated SiO ₂ particles. Next, 1.2 g of diethylamino methyltriethoxysilane, an amine silane coupling agent, and 0.5 g of n-octadecyl triethoxy silane as a dispersing agent, were added, followed by 1.5 at 50 ° C. After stirring for an hour, an amine group was introduced into the SiO ₂ particle surface (first step). Thereafter, 0.52 g of bromoethane was added as an ionizing agent to quaternize the amine group introduced on the surface of the SiO ₂ particle (second step) to give a positive charge, and an anionic organic dye was added thereto. 1.10 g of phosphoric acid blue 129 was added to the mixture of cations introduced to the surface of SiO ₂ particles with anions (-SO ₃ ⁻ ) of acid blue 129 to prepare a non-capsulated blue charged particle slurry. The blue charged particle slurry was injected into the electrophoretic display panel facing the negative electrode and the positive electrode, and a DC electric field was applied to confirm that the blue charged particle was moved to the negative electrode surface by electrophoresis. The electrophoretic starting voltage was 17 V. appear.

<Example 4>

As a suspension fluid, 1.0 g of SiO ₂ particles as an inorganic oxide was added to 50 g of chlorotrifluoroethylene, followed by sonication for 10 minutes to pulverize the aggregated SiO ₂ particles. Next, an amine-based silane coupling agent cyclohexyl-aminopropyltrimethoxysilane (cyclohexylaminopropyltrimethoxy silane) 1.5 g and cheomgahyeong dispersing agent Tween 80 (Aldrich Co.) was stirred for 3 hours at 40 ℃ was added 0.5 g of amine in the SiO ₂ particle surface Was introduced (step 1). Then, 0.45 g of propylchloride as an ionizing agent was added to quaternize the amine group introduced on the surface of SiO ₂ particles (second step) to give a positive charge, and an anionic organic dye was added thereto. 1.07 g of phosphorus acid green 25 was added to react with a cation introduced to the surface of SiO ₂ particles and an anion (-SO ₃ ⁻ ) of acid green 25 to prepare an uncapsulated green charged particle slurry. The green charged particle slurry was injected into the electrophoretic display panel facing the negative electrode and the positive electrode, and a DC electric field was applied to confirm that the green charged particle moved to the negative electrode surface by electrophoresis. The electrophoretic starting voltage was found to be 20V. .

As described in detail above, the present invention relates to a non-encapsulated colored charged particle slurry composition for electrophoretic display composed of an inorganic oxide, a silane coupling agent, a dispersing agent, a suspension fluid, an ionizing agent, and an anionic organic dye, and a method for preparing the same. As a non-capsule-type colored charged particle, according to the present invention, unlike the microcapsule-type particle of the prior art, the manufacturing method was simple and the stability was excellent. In addition, the colored charged particle slurry according to the present invention induces a repulsive force between the ions to enable good dispersion between the colored particles, there is an effect that the low voltage drive of less than 25V. In addition, since the present invention enables the production of red, blue, and green charged particles, which are not only white and black, but also three primary colors of light, it is possible to produce full color or area color electrophoretic displays.

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations are within the scope of the appended claims.

1A and 1B are explanatory views of driving a general microcapsule type electrophoretic display according to the prior art.

<Description of the symbols for the main parts of the drawings>

10,11 electrode 20: microcapsule

51.52: Power 21,22: Pigment Particles

2a and 2b is a conceptual diagram for explaining the non-encapsulated colored charged particles according to the present invention.

Figure 3 is a particle size distribution of the non-capsule-type white charged particles prepared by the present invention.

Figure 4 is a graph showing the luminance by voltage of the electrophoretic display panel manufactured using the non-capsule type white charged particles obtained in Example 1 of the present invention.

5A and 5B are photographic views of an electrophoretic display manufactured using the non-capsulated white charged particles obtained in Example 1 of the present invention ((a) Before Power Off (b) DC 21V Applied (Power On)].

Claims (6)

In the pigment slurry of the electrophoretic display, 0.1 to 15% by weight of inorganic oxide having hydroxyl group on the surface, 0.05 to 7% by weight of dispersant, 0.1 to 15% by weight of amine silane coupling agent, 40 to 99% by weight of suspension fluid, ion donating agent Non-encapsulated colored charged particle slurry composition for electrophoretic display, characterized in that 0.05 to 7% by weight, anionic organic dye 0 to 15% by weight. The non-capsulated colored charged particle slurry composition for electrophoretic display according to claim 1, wherein the inorganic oxide is titanium oxide (TiO ₂ ) and the anionic organic dye is 0% by weight, and the slurry is a white charged particle slurry. The non-capsulated colored charged particle slurry composition for electrophoretic display according to claim 1, wherein the inorganic oxide is silicon oxide (SiO ₂ ) and anionic organic dye is 0.1 to 8% by weight. The non-capsulated colored charged particle slurry composition for electrophoretic display according to claim 1, wherein the inorganic oxide having a hydroxyl group on the surface is introduced with a hydroxyl group on the surface of the inorganic oxide by plasma treatment. The anionic organic dyes of claim 1 and 3 are acid red series, acid blue series, acid green series, acid black series, acid biot. Non-capsulated colored charged particle slurry composition for electrophoretic display, characterized in that it comprises at least one material selected from acid violet series, acid orange series, and acid yellow series. In the production of pigments for electrophoretic displays, a first step of introducing an amine group on the surface of an inorganic oxide particle by adding an inorganic oxide, a dispersant, and an amine silane coupling agent having a hydroxyl group on the surface to a suspension fluid, and an ionizer The second step of forming a cation by reacting with the amine group introduced to the surface of the inorganic oxide particle by adding a 5 to 95 mol% anionic organic dye compared to the amine-based silane coupling agent of the first step to the inorganic oxide A method for producing non-encapsulated colored charged particles for electrophoretic displays, which is prepared by a third step of introducing an organic dye into an inorganic oxide by ionically bonding with a cation on a particle surface.