KR101312043B1 - Electrophoretic Microcapsule, Method of Preparing the Same and Display Panel Including the Same - Google Patents

Abstract

Electrophoretic microcapsules include a core material comprising pigment particles, a dielectric medium and a dispersant and a capsule wall surrounding the core material. It disperses the pigment particles, dielectric medium and dispersant to produce a core material, to prepare an aqueous solution containing a capsule wall material, to mix the surfactant and the core material in the aqueous solution, and to add a crosslinking agent or a curing agent Can be prepared. It is applicable to a display panel of a method of forming a pixel by microencapsulating the pigment particles having an electrophoresis, it is possible to reproduce the excellent color without a color filter.

Description

Electrophoretic Microcapsule, Method of Preparing the Same and Display Panel Including the Same}

The present invention relates to electrophoretic microcapsules, a method of manufacturing the same, and a display panel containing the same. More specifically, the present invention relates to electrophoretic microcapsules that can be used in a reflective display panel, a method of manufacturing the same, and a display panel containing the same.

Since the electrophoretic display device has high bistable stability, the electrophoretic display device retains the original image without applying an external electric field. Therefore, it is a kind of flat panel display using electrophoresis which has a function of storing an image without any additional energy, has excellent flexibility and portability, and has characteristics such as durability and light weight.

Such an electrophoretic display device has the characteristics closest to the paper texture. It is similar to or rather slightly higher than that of newspapers with a light reflection efficiency of about 40%, exhibits high light reflection efficiency, shows excellent contrast ratio, and drives electrophoretic floating particles by coating a transparent electrode on a thin, bendable base film such as paper or plastic. As a reflective display, the device is expected to attract more attention in the future with a distinction from a liquid crystal display, a plasma display panel, and an organic electroluminescent device.

The electrophoretic display using the electrophoretic phenomenon is a core element of the flexible display, and is based on the electrophoretic property of applying electromagnetism to the conductive material to make it moveable. The electrophoretic display disperses the charged fine particles among the thin flexible substrates. The image is then expressed as a change in the arrangement of the microparticles due to a change in the polarity of the electromagnetic field. In detail, non-luminescent reflection information using a phenomenon in which positively charged particles move to a negative electrode to display the color of these particles when an external electric field is applied, and particles move inversely to display a color of fluid when a positive voltage is applied to the particles It is a display device. When electrophoresis occurs in the core composition, the charged particles move at a rate determined by the dielectric properties and charge of the fluid, the strength of the applied electric field, and the viscous drag.

The electrophoretic display developed by E-ink of the United States uses a blue dielectric medium on titanium dioxide (TiO ₂ ) particles with excellent white reflectance to produce a white image on a blue background. Microcapsules were prepared by dispersing positively charged white particles and negatively charged black particles to enable black / white display.

The microcapsule is composed of a dielectric medium and a capsule coated to surround a plurality of white charged particles and a plurality of black charged particles in the dielectric medium, which are provided between upper and lower transparent electrodes stacked on upper and lower substrates.

Due to the high density of the particles themselves, the charged particles in the microcapsules may cause clustering and agglomeration of particles due to dispersion instability over time, thereby affecting the bistable stability of the particles. In order to solve the above problems and to impart a charge for bistable and electrophoresis, E-ink uses functional polymers such as thermoplastic vinyl polymers, thermoplastic silicone polymers, thermosetting polymers or copolymers of these monomers. The coating was carried out to control the specific gravity of the pigment and impart a charge to the surface.

However, this method must maintain the same specific gravity between the charged particles of two colors and the dielectric medium, prevent the aggregation between the two charged particles, and physical and chemical treatments for charge attachment to have electrophoretic mobility Required. This chemical treatment results in a functional organic polymer core-shell polymer treatment process on the color pigment particles. This requires a very complicated process and a lot of manpower and time, and has the disadvantage of affecting particle mobility and color clarity due to the thickness of the polymer layer when encapsulated and driven.

In addition, E-Ink Co., Ltd. has also placed microcapsules containing black / white particles on a flat substrate and colored filters to realize the color of electronic paper, considering that it is difficult to form fine pixels on a flat substrate of microcapsules containing color pigment particles. Although a technique for implementing a variety of color displays has been proposed, this method has a disadvantage in that the gradation and sharpness of colors are very poor. In the microcapsules for display including electrophoretic particles, various manufacturing methods can be realized. Technology is urgently requested.

Accordingly, it is an object of the present invention to provide an electrophoretic microcapsule comprising a core material capable of realizing high color clarity.

Another object of the present invention is to provide a method for preparing the electrophoretic microcapsules.

Still another object of the present invention is to provide a display panel including the electrophoretic microcapsules.

Electrophoretic microcapsules according to the present invention for achieving the above object is a core material comprising a pigment particle, a dielectric medium and a dispersant; And a capsule wall surrounding the core material.

In one embodiment, the pigment particles may be core-shell coated with at least one ionized hydrophilic organometallic compound and at least one lipophilic organometallic compound.

In one embodiment, the organometallic compound may be at least one selected from the group consisting of silicon compounds, titanium compounds, zirconium compounds and aluminum compounds.

In one embodiment, the core material may be at least one of the white pigment particles, black pigment particles, red pigment particles, green pigment particles and blue pigment particles are uniformly dispersed in the dielectric medium.

In one embodiment, the pigment particle is an organic pigment comprising an azo pigment, a cyanine pigment including a phthalocyanine pigment and an anthraquinone pigment, cadmium red pigment, molybdenum red pigment, cobalt green pigment It may be at least one selected from the group consisting of inorganic pigments, including cobalt blue pigments, manganese violet pigments and cobalt violet pigments.

In one embodiment, the microcapsules may include 30 to 80% by weight of the dielectric medium, 10 to 50% by weight of the pigment particles and 10 to 20% by weight of the dispersant.

In one embodiment, the diameter of the microcapsules may range from 20 microns to 60 microns.

Another object of the present invention described above,

Dispersing the pigment particles, the dielectric medium and the dispersant to prepare a core material;

Preparing an aqueous solution comprising the capsule wall material;

Mixing a surfactant and the core with the aqueous solution; And

It is achieved by a method for producing an electrophoretic microcapsule comprising the step of adding a crosslinking agent or a curing agent.

In one embodiment, after the step of mixing may be further performed to adjust the pH to the range of 4.5 ~ 5.5.

In one embodiment, the capsule wall material is gelatin, acacia gum, carboxymethylcellulose, carrageenan, casein, albumin, hydrolyzed styrene anhydride copolymer, methyl vinyl ether co-maleic anhydride and cellulose phthalate It may be at least one selected.

In one embodiment, the surfactant is used in the range of 0.1 to 1.0% by volume based on the volume of the core material, for example, cetyl trimethyl ammonium chloride, octadecyl trimethyl ammonium chloride), trimethyltetradecyl ammonium bromide, and at least one of dodecyl trimethylammonium bromide (DTAB).

In one embodiment, the crosslinking agent or curing agent may be an aldehyde compound including formalin (Formaline 37%) and glutaric aldehyde (Glutaric dialdehyde).

Another object of the present invention described above

A substrate having a cell structure defined by barrier ribs; And

It is achieved by a display panel encapsulated in the cell structure and comprising electrophoretic microcapsules comprising a core material comprising pigment particles, a dielectric medium and a dispersant and a capsule wall surrounding the core material.

In one embodiment, the partition wall may be any one of a grid shape and a stripe shape.

In an embodiment, the substrate may be a lower electrode substrate, and may further include an upper electrode substrate facing the lower electrode substrate with respect to the microcapsules.

In one embodiment, the microcapsules may be mixed with a water-soluble binder.

In one embodiment, the water-soluble binder is a cellulose-based 1-10% aqueous solution, can be mixed in the range of 5 to 40% by weight based on the total microcapsules.

In one embodiment, the water-soluble binder is hydroxy propyl methyl cellulose (HPMC), hydroxy ethyl cellulose (HEC), hydroxypropyl cellulose (HPC), ethyl hydroxy ethyl Cellulose (ethyl-HEC; EHEC), methyl ethyl hydroxy ethyl cellulose (methyl-ethyl-HEC; MEHEC), butyl glycidyl ether hydroxy ethyl cellulose (butylglycidylether-HEC), lauryl glycidyl ether hydroxy ethyl cellulose (laurylglycidylether-HEC), carboxymethylated MHEC (carboxymethylated MHEC), carboxymethylated MHPC (sodium carboxymethylcellulose (Na-CMC)) can be used.

According to the present invention, it has electrophoretic properties that enable electrical movement due to electric charges imparted to the surface of color pigment particles in the dielectric medium in the electrophoretic microcapsules, and an electric bistable property that can reduce power consumption in driving. In addition, the pigment particles are made of a low coating layer was developed to increase the gradation of the color expression and the electrophoretic reaction rate, and the microcapsules carrying the same have a uniform size and can be obtained with high yield. There is no coagulation between the prepared microcapsules and there is no problem in stability during long-term storage. A capsule film may be manufactured and applied to the lower electrode substrate having a partition structure so as to be easily disposed, and a display panel capable of excellent color reproduction without a color filter may be manufactured.

1 is a flow chart showing a method for producing an electrophoretic microcapsules according to an embodiment of the present invention.
Figure 2 is a photograph of the electrophoretic microcapsules prepared according to an embodiment of the present invention.
3A to 3D are cross-sectional views illustrating a process for fabricating a cell array having a partition structure using a master.
4A to 4C are cross-sectional views illustrating a process for manufacturing a cell array having a partition structure using photoresist.
5A and 5B are planar photomicrographs of a lower electrode substrate of a partition-cell structure manufactured according to an embodiment of the present invention, and FIG. 5A is an electrode substrate having a lattice structure, and FIG. 5B has a stripe structure. It is about an electrode substrate.
6 is a cross-sectional view of a display panel according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. In the accompanying drawings, the dimensions of the structures are enlarged to illustrate the present invention in order to clarify the present invention.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, the terms "comprising ", or" having ", and the like, are intended to specify the presence of stated features, integers, steps, operations, elements, or combinations thereof, , Steps, operations, elements, or combinations thereof, as a matter of principle, without departing from the spirit and scope of the invention.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, the present invention will be described in detail.

According to the present invention, in order to give the electrophoretic properties, the surface charge is removed, and in order to obtain the bistable properties, it is avoided from the existing process of the functional organic polymer coating manufacturing method for the purpose of controlling the particle specific gravity. In other words, electrophoresis is performed by introducing a sol-gel process for simple reaction time control and post-treatment process to coat various functional organometallic compounds on the surface of pigment particles through hydrolysis condensation reaction. Pigment particles were prepared first. The microcapsules were coated to form an electronic ink composition consisting of a dielectric medium in which the pigment particles were dispersed and the ink composition as a core, and to surround the surroundings in a spherical shape.

In addition, the present invention provides an electrophoretic display panel comprising the electrophoretic microcapsules. The electrophoretic display panel according to the present invention includes an upper electrode substrate and a lower electrode substrate facing each other, and a plurality of electrophoretic microcapsules provided between the upper and lower electrode substrates.

The lower electrode substrate is preferably formed by attaching a film on which the ITO is deposited to the partition structure cell array using a dot / adhesive agent. The electrophoretic microcapsules prepared above may be disposed on the partition structure cell array using various coating methods, and the upper electrode substrate may be sealed with a dot / adhesive to form a display panel such as an electronic paper display panel.

The manufacturing process of the display panel according to the present invention is divided into several steps as follows.

a) coating the organometallic compound on the pigment particles by a sol-gel method; b) dispersing pigment particles coated with an organometallic compound in a dielectric medium to produce a core material; c) preparing microcapsules using the core material and the capsule wall material; d) forming a bottom electrode substrate of a partition-cell structure; e) forming a capsule pixel on the lower electrode substrate and pasting the upper electrode substrate to form an entire panel.

Hereinafter, the manufacturing steps of the electrophoretic microcapsules according to the embodiment of the present invention will be described.

1 is a flow chart showing a method for producing an electrophoretic microcapsules according to an embodiment of the present invention. This will be described with reference to FIG. 1.

Microcapsules for electrophoretic display panels include a core material composed of a dielectric medium and one or more pigment particles dispersed in the dielectric medium and endowed with a polarized charge of a polar functional group, and the core material, that is, the dielectric medium. And a capsule wall material surrounding the pigment particles.

a) coating the pigment particles with an organometallic compound sol-gel method

The pigment particles of the microcapsules are composed of a composition of inorganic compounds having polar functional groups and color composite particles including pigments. The color composite particles are white pigments and black, which are imparted with a polarizable positive charge of the polar functional groups. Pigments, red pigments, green pigments, blue pigments, and the like, and may be dispersed in a dielectric medium.

In electrophoretic displays using microcapsules, the optical contrast ratio consists mainly of the movement of charged pigment particles dispersed in the dielectric medium. For example, when the charged particles move toward the observer, the charged particles scatter the incident light to show the color of the particles. In this case, when the charged particles are blue particles, they are blue, and when green particles are green. Thus, a visual contrast ratio can be achieved. As such, in the electrophoretic display, the color image may be expressed by mixing the pigment composition included in the core, in particular, the color mixture of light emitted through the capsule containing the pigment expressing the colors of red, green, and blue. will be.

In the electrophoretic display using microcapsules, the following functionalities should be given to clearly realize various colors using the pigment composition. That is, light must be scattered or absorbed by the moving charged particles, and the charged particles move smoothly so that polarization can occur at low voltage without resistance such as agglomeration with each other, and maintain the state even after the polarization occurs. The electrical properties of the particles should not be altered.

Conventionally, the core particles of the microcapsules of the electrophoretic display are coated with a functional polymer to give a charge for electrophoresis, thereby controlling the specific gravity of the pigment and imparting a charge to the surface. However, this method increases the complexity of the process by thickening the organic core-shell coating, which requires a lot of time, manpower, and inability to produce uniform particles. The voltage may be high, and due to the aggregation of organic materials during repeated driving, it may cause a problem of deterioration of double safety.

According to an embodiment of the present invention, it is possible to core-shell coat an organometallic compound having various functional groups on the surface of pigment particles through a method using a sol-gel process with little post-treatment process while applying a non-trivial reaction. Do. Accordingly, the electrophoretic properties and the mobility of the particles due to the thin coating layer can be improved to improve the clarity of the color and the contrast ratio of the color, and also to realize the electric bistable properties at once.

The organometallic compound through the sol-gel process serves to charge the coated pigment particles by polarization. The organometallic compound has a polar functional group and is polarized by an induced current between the anode and the cathode. At this time, the material that can be used is the organometallic compound used in the sol-gel process for core-shell coating on the surface of the color particles, at least one metal such as silicon compound, titanium compound, zirconium compound, aluminum compound, etc., these The materials may be applied alone or in combination.

According to the present invention, single or complex color particles coated with the organometallic compound are present in the microcapsules. Pigment compositions composed of single or colored multiparticulates may be pure compounds or mixtures of compounds for reaching a particular color. The pigment composition included in the microcapsules according to the present invention is at least one of white, black, red, green, blue to which the polarized charge of the polar functional group is given. Include. These may be contained alone or in more than one, and preferably contain two colors.

The pigment composition may include an organic or inorganic pigment, and in the present invention, the pigment may be used alone or in combination of two or more thereof. Important factors to consider here include light resistance, solubility in dielectric media, color and cost. The pigment may be a pure compound or a mixture of pigments for reaching a particular color, including color.

While there are a variety of pigments that can be selected for use in electrophoretic microcapsules, pigments with high color development and high heat resistance, in particular pigments with high thermal decomposition resistance, are preferred and organic or inorganic pigments can be used. Useful pigments include azo pigments, cyanine pigments including copper phthalocyanine pigments, organic pigments such as anthraquinone pigments, or TiO2, calcium carbonate, talc, black iron oxide, cadmium red, cadmium yellow, cobalt green, cobalt blue, manganese. Inorganic pigments, such as violet and cobalt violet, or carbon black etc. are mentioned.

Preferably, the present invention is coated with an organometallic compound disclosed in Patent Application No. 10-2011-0145370 filed December 28, 2011 under the name of the invention "ink composition, a method for producing the same and a display panel containing the same" Pigment particles may be applied.

b) preparing a core material by dispersing pigment particles coated with an organometallic compound in a dielectric medium.

Electrophoretic microcapsules according to the present invention comprises a core containing an organic and inorganic pigment particles and a dielectric medium coated with the organometallic compound and a capsule wall material capable of supporting the same. It has a uniform mobility over a certain range under an electric field. Electrophoretic microcapsules are preferably prepared in capsule sizes that are easy to apply to electrophoretic display panels. For example, by placing microcapsules on the lower electrode of the lower partition-cell structure, which will be described below, capsule size may be desired for screen printing and dispensing while improving color clarity, reproducibility, and contrast ratio. Preferably has a diameter within the range of 20 microns to 60 microns.

Dielectric oil in the core material of the microcapsules may be selected and applied in accordance with the relationship between the chemical inertness, the density in harmony with the electrophoretic particles or the chemical miscibility of the electrophoretic particles and the capsule wall. . Organic solvents such as hexadecane hydrocarbons, decahydronaphthalene, 5-ethylidene-2-norbornene, toluene aromatic hydrocarbons, and xylene , Dodecyl benzene, polychlorotrifluoroethylene (Halocarbon Oil), isopar-G (Isopar-G), isopar-H ) May be used. The dielectric medium may be used in one or more mixtures.

Such organic solvents preferably have low dielectric constant, high volume resistivity, low viscosity, low toxicity and low water solubility, high specific gravity and low reflection index. In particular, the dielectric constant preferably has a low dielectric constant in the range of 2 to 30. In addition, the dielectric medium prevents agglomeration of the surface modifier for modifying the surface energy or charge of the electrophoretic particles or the binding capsule and the charge control agent and the electrophoretic particles to increase mobility to the electrophoretic particles, and the electrophoretic particles are irreversibly encapsulated. Stabilizers may be further included to prevent deposition on the wall surface.

One embodiment of the present invention is to use a dispersant having a polar group at the terminal to exhibit both the role of the surface modifier, the charge control agent and the role that the pigment particles can be stably dispersed in the dielectric medium without aggregation and interaction. Available dispersants include BYK-102, BYK-106, BYK-108 and Solspers solsperse 5000, solsperse 8000, solsperse 11200, solsperse 12000, solsperse 13300, solsperse 20000, solsperse 22000, solsperse 32000, solsperse 38500 For example, solsperse 40000, solsperse 41000, solsperse 41090, solsperse 43000, solsperse 44000, solsperse 46000, solsperse 53000. The dispersant may be used alone or in combination of one or more for the desired amount of charge and dispersion stability.

The pigment particles, the dielectric medium, the dispersant, and the like described above are mixed at an appropriate ratio to form a core material of the microcapsules (step S10). The proper ratio of pigment particles in the core material is in the range of 10 to 50% by weight of the total core material in consideration of color reproducibility and hiding power. If less than 10% by weight, color reproducibility and concealment is difficult to achieve, and when more than 50% by weight, the dispersion stability is lowered in the dielectric medium.

In addition, the mixing amount of the dielectric medium is suitably 30 to 80% by weight in the total core material. If less than 30% by weight, the viscosity of the core material and the mobility of the particles may be affected by increasing the driving voltage, and when used in excess of 80% by weight may affect the dispersion stability of the pigment particles.

The amount of the dispersant should be in the range of 10 to 20% by weight in the total core material. If it is less than 10% by weight it may lower the dispersion stability and efficiency, and if it exceeds 20% by weight may affect the driving due to the self-aggregation of the dispersant and the rise of the viscosity of the core material.

The mixture of the pigment particles, the dispersion medium and the dispersant in an appropriate ratio is conventional, such as ultrasonic dispersion, dyno mill dispersion, 3-roll mill, high speed stirring, colloid mill, etc. It can disperse | distribute using the disperser used for paint manufacture. In the present invention, the use of a specific disperser is not limited. Preferably, using a dynomill and a three-roll mill can maximize the dispersion stability of the pigment particles at the same dispersion time.

c) preparing microcapsules using core material and capsule wall material

The microencapsulation of the core material (including pigment particles, dielectric medium and dispersant) made by the above dispersion method is manufactured by coacervation method to easily form pixels on the partition-cell type lower electrode substrate to be described below. .

First, a wall material comprising at least one selected from gelatin, acacia gum, carboxymethylcellulose, carrageenan, casein, albumin, hydrolyzed styrene anhydride copolymer, methyl vinyl ether co-maleic anhydride and cellulose phthalate ) Is dissolved in water to prepare an aqueous solution (step S20). After mixing the appropriate surfactant in the prepared aqueous solution, the core material prepared above is added at an appropriate rate to prepare an emulsion (step S30).

The surfactant collects the core material added to the aqueous solution primarily, stably protects the core material in the aqueous solution, and serves to control the size and yield of the final capsule. Surfactants that can be used in the present invention can be selected from anionic, cationic and nonionic surfactants.

In particular, in the present invention, it is preferable to use a cationic surfactant that is stable at the same content and has less aggregation between capsule walls than the use of an anionic surfactant. Specific examples include cetyl trimethyl ammonium chloride, octadecyl trimethyl ammonium chloride, trimethyltetradeclammonium bromide, and dodecyl trimethylammonium bromide (DTAB). Can be used.

The amount of the surfactant is preferably in the range of 0.1 to 1.0% by volume relative to the volume of the core material. If the content of the surfactant is less than 0.1% by volume, the core material does not form a stable emulsion in the aqueous solution, so the capsule is severely broken. If the content is more than 1.0%, the emulsion particles are too small in the aqueous solution, and the final capsule size becomes smaller. This is because hepatic aggregation can occur.

Next, the pH, temperature, etc. of the emulsion are adjusted to induce phase seperation, so that the wall material rises above the core material, and then a crosslinking agent or a curing agent is added (step S40). This is a process of adjusting the strength of the wall material to produce a microcapsule through this process (step S50). As the crosslinking agent or curing agent, aldehydes such as formalin (37%) and glutaric aldehyde (Glutaric dialdehyde) can be used.

The pH control range for phase separation is generally adjusted to be about acidic (5.5 to 4.5) rather than the acidic (3.0 to 4.5) range, and the pH adjustment is controlled to minimize the control rate. Minimize the aggregation between capsules due to the phase change.

Figure 2 is a photograph of the electrophoretic microcapsules prepared according to an embodiment of the present invention.

d) forming a bottom electrode substrate of a partition-cell structure;

In order to manufacture the display panel, the microcapsules manufactured according to the above-described method are included between the upper and lower electrode substrates. The lower electrode substrate may be manufactured by various methods. For example, a barrier rib array or photoresist (PR) formed using a master mold having a barrier rib cell using a thermosetting or thermoplastic and UV curable resin composition may be formed. A film and a glass plate on which ITO is deposited may be attached to a partition structure cell array formed by using a dot / adhesive to be formed.

Fabrication of bulkhead cell array using master

3A to 3D are cross-sectional views illustrating a process of manufacturing a cell array having a partition structure using a master.

As shown in Fig. 3A, a master mold 10 having a structure of a partition wall formed in an intaglio or embossed form is fabricated. Next, after applying the mold material layer using the master mold 10, the mold mold layer is demolded to produce a soft mold 20 as shown in FIG. 3B. Next, referring to FIG. 3C, a UV curing solution is applied to the soft mold 20 to form a curing solution layer 30. Referring to FIG. 3D, the curing liquid layer 30 is irradiated with a predetermined amount of UV, cured, cured, and then demolded to produce a cell array. FIG. 5A is a plan view of a cell array having a partition structure manufactured in FIG. 3D.

According to another embodiment of the present invention, the barrier ribs are formed using photoresist similarly to those used in semiconductors or other displays. The partition material is a UV curable composition and is applied by spin coating or dispensing. The coated photoresist is fabricated by etching / developing after pattern exposure or by printing a partition array. As a process for such a partition formation method, the screen printing method, the sand blasting method, the lift-off method, the photolithography method, etc. are mentioned.

Example of barrier formation method using photoresist

4A to 4C are cross-sectional views illustrating a method of forming a partition wall using photoresist. Referring to FIG. 4A, a photoresist is applied on the substrate 100 to form a photoresist film 110. Referring to FIG. 4B, when the photoresist layer 110 is exposed using a photomask 120 having a pattern for forming a partition, the exposed portion is crosslinked to change to an insoluble portion. Referring to FIG. 4C, the exposed photoresist film 110 is developed to remove the soluble portion, which is the unexposed portion of the photoresist film 110, and form the partition 110a while leaving the insoluble portion.

In addition to the above-described method, after placing the electrophoretic microcapsules using various coating methods, the upper substrate may be coalesced with a dot / adhesive to form a display panel.

The cross-sectional pattern of the partition wall-cell for pixel formation of the color microcapsules may be formed in a grid pattern as shown in FIG. 5A to improve color reproducibility and color clarity, and is shown in FIG. 5B to facilitate capsule printing on the pixel. As shown, it may be formed in a stripe-shaped pattern. In addition, the size of the unit cell of the barrier rib structure may vary according to the degree of demand for image quality for the final application, and the size adjustment of the unit cell according to the demand can be implemented by changing the pattern of the photomask or the master structure design.

e) forming a capsule pixel on the lower electrode substrate and pasting the upper electrode substrate to form an entire panel;

Pixels of the microcapsules are arranged on the manufactured barrier-cell using various coating methods. For example, a plurality of microcapsules may be disposed on the partition wall using a screen printing method and a dispensing method.

In order to print the microcapsules, the capsule and the water-soluble binder may be mixed in an appropriate ratio to adjust the viscosity and viscosity. In this invention, manufacture is easy in aqueous solution, and even a small amount can obtain a viscosity thickening effect. A cellulose compound which can be soluble can be used as the water-soluble binder in consideration of the adhesion force to the partition wall-cell and the like.

Specific examples of soluble cellulose include hydroxy propyl methyl cellulose (HPMC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), ethyl hydroxy ethyl cellulose (HPC). ethyl-HEC (EHEC), methyl ethyl hydroxy ethyl cellulose (methyl-ethyl-HEC; MEHEC), butyl glycidyl ether hydroxy ethyl cellulose (butylglycidylether-HEC), lauryl glycidyl ether hydroxy ethyl cellulose (laurylglycidylether -HEC), carboxymethylated MHEC (carboxymethylated MHEC), carboxymethylated MHPC (sodium carboxymethyl cellulose (Na-CMC)), etc. are mentioned.

The water-soluble binder is preferably prepared in 1 ~ 10% aqueous solution, it is good to mix in the range of 5 to 40% by weight based on the total microcapsules.

More preferably, the water-soluble binder may use sodium-carboxymethylcellulose (Na-CMC). It is preferable to prepare Na-CMC (Sodium-carboxymethylcellulose) in 1 to 5% aqueous solution, and to use Na-CMC aqueous solution used in the range of 5 to 30% by weight based on the total capsule weight as a binder.

By performing the above method, the upper electrode plate including the film or glass plate on which ITO is deposited on the electrode lower electrode plate on which pixels are formed by microcapsules is laminated using a dot / adhesive to complete the panel.

6 is a cross-sectional view of a display panel manufactured according to an embodiment of the present invention.

Referring to FIG. 6, a plurality of partition walls 240 are formed between the lower electrode substrate 210 and the upper electrode substrate 220 spaced at predetermined intervals, and the microcapsules 250 are formed in the partition wall 240. This is arranged. Reference numeral 230 is a sealing material.

The upper electrode substrate of the completed panel uses ITO transparent electrode as a common electrode, and the lower electrode substrate of the partition-cell structure has independent pixel electrodes positioned according to each partition-cell type, so that color images can be displayed without color filters. It can be implemented.

Hereinafter, the present invention will be described in more detail with reference to Examples, but embodiments according to the present invention can be modified in many different forms, and the scope of the present invention is construed as being limited to the embodiments described below. Can not be done.

≪ Example 1 >

a) coating the organometallic compound on the pigment particles by sol-gel method

40 wt% of Dupont's white TiO ₂ R-706 particle pigment and 40 wt% of isopropyl alcohol were mixed with 20 wt% of polyvinyl alchol (PVA), followed by high speed stirring at 3000 rpm with 5 mm zirconia beads for 3 hours. After stirring, the zirconia beads and the dispersion were separated using a 50 μm filter.

In a flask capable of stirring, 50% by weight of the particle-dispersed solution, 20% by weight of phenylaminopropyltrimethoxysilane, and 20% by weight of ethyl alcohol were added, and the temperature was raised to 50 ° C after about 1 hour of stirring. 10 weight% of distilled water was dripped after 30 minutes of temperature rising. After completion of the dropwise addition, the reaction was carried out for 6 hours, followed by vacuum filtering to separate ethyl alcohol. And completely dried in a vacuum oven for 12 hours to obtain a white color pigment particles core-cell coated with an organometallic compound.

Instead of the white pigment, red Pigment Red 224 particles were used in the same amount to obtain red color pigment particles core-cell coated with an organometallic compound according to the same process.

b) preparing a core material by dispersing pigment particles coated with an organometallic compound in a dielectric medium.

50% by weight of Dupont's white TiO ₂ R-706 particles, 20% by weight of dispersant BYK-106, and 30% by weight of halocarbon among the colored particles coated with an organometallic compound, followed by 0.5 mm bead mill It was dispersed for 3 hours.

Next, red Pigment Red 224 particles coated with an organometallic compound were uniformly mixed in the same ratio as the mixing ratio of the white pigment, the dispersant, and the dielectric medium, and dispersed using a dino mill.

Finally, the dielectric medium dispersion of the colored particles coated with the organometallic compound of the two colors was prepared by 40% by weight of the white color dispersion, 20% by weight of the red color dispersion, 30% by weight of Halocarbon1.8 and 10% by weight of Isopar-G. Each was mixed and dispersed using a basket-type sonicator for about 30 minutes to prepare a core material of the microcapsules.

c) preparing microcapsules using core material and capsule wall material

500 g DIW (deionzed water) was added to a double jacket flask capable of hot water heating, and the temperature was raised to 40 ° C. 10 g of gelatin-A (Porcine gelatin, Sigma-aldrich) was added and dissolved at 200 rpm with no agitation. 100 g of a 10% aqueous gum solution (Acarcia gum, Sigma-aldrich) was slowly added thereto, and stirred uniformly for 30 minutes while suppressing bubble generation at 200 rpm. Thereafter, 100 ml of the core material prepared above was added into an aqueous solution rather than in the air using a separatory funnel.

The stirrer was changed from a general stirrer to a homo-mixer and the speed was 800 to 1000 rpm, and stirred for 10 minutes, and then the pH was adjusted to 4.5 to 5.0 using acetic acid. At this time, change the stirrer to a general stirrer, not a homomixer, and the stirring speed is 300 ~ 400rpm and cooled to 10 ℃, and when the contents are cooled, 20g of a 50% aqueous solution of glutaraldehyde, a crosslinking agent is added, and the internal temperature is raised to 25 ℃ After maintaining for 3 hours or more to prepare a color microcapsules.

The prepared microcapsules were excellent in the aggregation and bistable stability of the internal particles and the aggregation and storage stability of the capsule itself. In addition, the clarity of the colors is higher. The characteristics of the microcapsules prepared in Table 1 are shown in comparison with those for conventional capsules.

division Invention Technology capsule size (㎛) 20-60 20 to 40 The driving voltage (V) 15 20 Response speed (msec) 200 300 Contrast Ratio (Black / while Standard) 10: 1 6: 1 Color Reproduction Rate (%) 10% 8%

d) forming a bottom electrode substrate of a partition-cell structure;

A master mold was formed by engraving the structure of the partition into an intaglio or an embossed structure, and a UV curing solution was applied to produce a mold after irradiating a predetermined amount of UV. The fabricated bulkhead has a bulkhead-cell structure, and each of the independent cells is fabricated in a square shape of 200 microns and 200 microns in length.

e) forming an encapsulation pixel on the lower electrode substrate and pasting the upper electrode substrate to form an entire panel;

70 wt% of the 20 ~ 40 micron diameter microcapsules prepared in step c) and 30% by weight of a Na-CMC (sodium-carboxymethylcellulose) 5% aqueous solution binder were added at a stirring speed of 200 to 300 rpm. The mixture was stirred for 10 minutes with a wing impeller stirrer to uniformly mix the capsule and the binder.

Then, the needle inner diameter of the dispenser (needle) 170 microns outer diameter 200 microns mounted on the lower electrode substrate of the partition-cell structure prepared in step d) and then dispensing in the partition-cell at a moving speed of 30 ~ 40mm / sec (Dispensing) to form a pixel. After drying for 2 hours in a constant temperature, a humidity chamber set to 50% humidity, 50 ℃ internal temperature to prepare a lower electrode substrate on which a color electrophoretic microcapsule pixel was formed.

The upper electrode substrate coated with a pressure-sensitive adhesive 10 to 15 microns thick on a previously prepared ITO deposited transparent film on the completed lower electrode substrate was laminated using upper and lower electrode substrates using a laminator, and finally a color microcapsule display panel was completed. .

Since the manufactured display panel can be manufactured by directly patterning color capsules, color display can be performed without a color filter.

According to the present invention as described above, it is applicable to a display panel of the method of forming a pixel by microencapsulating the pigment particles having electrophoresis. Excellent color reproduction is possible without color filters and excellent color contrast characteristics, and clear image quality is possible.

Unlike the image implementation using the backlight used in the existing LCD and PDP display panels, the present invention is not only applicable to the reflective display panel by external light, but also thin and flexible because no light source called a backlight is required in the panel. It can be applied to one display panel.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

Claims (18)

At least one ionized hydrophilic organometallic compound and at least one lipophilic organometallic compound are core-shell coated on the surface thereof with 10 to 50% by weight of pigment particles imparted with a positive polarity charge, 30 to 80% by weight of dielectric medium and dispersant Core material including 10 to 20% by weight; And
An electrophoretic microcapsule comprising a capsule wall surrounding the core material and having a diameter in the range of 20 microns to 60 microns. delete The microcapsule of claim 1, wherein the organometallic compound is at least one selected from the group consisting of a silicon compound, a titanium compound, a zirconium compound, and an aluminum compound. The microcapsule of claim 1, wherein at least one of the white pigment particles, the black pigment particles, the red pigment particles, the green pigment particles, and the blue pigment particles is uniformly dispersed in the dielectric medium. The method of claim 1, wherein the pigment particles are azo pigments, organic pigments including cyanine pigments and phthalocyanine pigments including phthalocyanine pigments, cadmium red pigments, molybdenum red pigments, cobalt green pigments Microcapsule, characterized in that at least one selected from the group consisting of cobalt blue pigments, manganese violet pigments and inorganic pigments including cobalt violet pigments. delete delete At least one ionized hydrophilic organometallic compound and at least one lipophilic organometallic compound are core-shell coated on the surface thereof with 10 to 50% by weight of pigment particles imparted with a positive polarity charge, 30 to 80% by weight of dielectric medium and dispersant Preparing a core material including 10 to 20 wt%;
Preparing an aqueous solution comprising the capsule wall material;
Mixing a surfactant and the core with the aqueous solution;
Adjusting the pH to a range of 4.5 to 5.5 after the mixing; And
Method of producing an electrophoretic microcapsule comprising the step of adding a crosslinking agent or a curing agent. delete The method of claim 8, wherein the capsule wall material is gelatin, acacia gum, carboxymethylcellulose, carrageenan, casein, albumin, hydrolyzed styrene anhydride copolymer, methyl vinyl ether co-maleic anhydride and cellulose phthalate Method for producing a microcapsule, characterized in that at least one selected. The method of claim 8, wherein the surfactant is used in the range of 0.1 to 1.0% by volume based on the volume of the core material and is used in the cetyl trimethyl ammonium chloride, octadecyl trimethyl ammonium chloride (tridecyl trimethyl ammonium chloride), trimethyl Tetradecyl ammonium bromide (trimethyltetradecylammonium bromide) and DTAB (Dodecyl Trimethylammonium bromide) A method for producing a microcapsule, characterized in that at least one selected from the group consisting of. The method of claim 8, wherein the crosslinking agent or curing agent is an aldehyde compound containing formalin (Formaline 37%) and glutaric aldehyde (Glutaric dialdehyde). A substrate having a cell structure defined by barrier ribs; And
10-50% by weight of the pigment particles encapsulated in the cell structure, at least one ionized hydrophilic organometallic compound and at least one lipophilic organometallic compound are core-shell coated on the surface thereof to impart polarized positive charge, and a dielectric medium. A display panel comprising a core material comprising 30 to 80% by weight and a dispersant 10 to 20% by weight and an electrophoretic microcapsule having a diameter in the range of 20 microns to 60 microns, the capsule wall surrounding the core material. The display panel of claim 13, wherein the partition wall has any one of a lattice shape and a stripe shape. The display panel of claim 13, wherein the substrate is a lower electrode substrate and further includes an upper electrode substrate facing the lower electrode substrate with respect to the microcapsules. The display panel of claim 13, wherein the microcapsules are mixed with a water-soluble binder. The method of claim 16, wherein the water-soluble binder is a water-soluble cellulose-based compound, which is 1 to 10% aqueous solution, characterized in that used in the range of 5 to 40% by weight based on the total microcapsules. Display panel. The method of claim 17, wherein the water-soluble binder is hydroxy propyl methyl cellulose (HPMC), hydroxy ethyl cellulose (HEC), hydroxypropyl cellulose (HPC), ethyl hydroxy ethyl Cellulose (ethyl-HEC; EHEC), methyl ethyl hydroxy ethyl cellulose (methyl-ethyl-HEC; MEHEC), butyl glycidyl ether hydroxy ethyl cellulose (butylglycidylether-HEC), lauryl glycidyl ether hydroxy ethyl cellulose (laurylglycidylether-HEC), carboxymethylated MHEC (carboxymethylated MHEC), carboxymethylated MHPC (carboxymethylated MHPC) and sodium carboxymethyl cellulose (sodium-carboxymethylcellulose; Na-CMC) Display panel.

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