JP2003315849A - Particle and apparatus for displaying image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a particle and an apparatus for displaying an image by which the particle having uniform charge quantity distribution can be obtained and control of coloring degree and of charge quantity is easy, an excellent image having sufficient contrast can be stably obtained in an image display device in which at least two kinds of particles are enclosed between a transparent substrate and a counter substrate and the particles are made to fly and move to display the image. <P>SOLUTION: The particle for displaying the image which is produced by blending a resin with a colorant and a charge controlling agent, if necessary, kneading and crushing the obtained mixture and then smoothing a particle surface, is used. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device capable of repeatedly displaying and erasing an image as particles fly and move by utilizing Coulomb force and the like, and particles for image display.

[0002]

2. Description of the Related Art As an image display device replacing liquid crystal (LCD), an image display device (display) using a technique such as an electrophoretic system, an electrochromic system, a thermal system, and a two-color particle rotation system has been proposed. These image display devices are considered as next-generation inexpensive display devices because they have a wider viewing angle than ordinary printed matter, lower power consumption, and a memory function than LCDs. Therefore, it is expected to be applied to displays for mobile terminals and electronic papers.

Recently, an electrophoretic method has been proposed in which a dispersion liquid composed of dispersed particles and a coloring solution is formed into microcapsules and the microcapsules are arranged between opposed substrates. However, the electrophoretic method has a problem that the response speed is slow due to the viscous resistance of the liquid because the particles migrate in the liquid. Further, since particles having a high specific gravity such as titanium oxide are dispersed in a solution having a low specific gravity, there is a problem in that they easily settle, it is difficult to maintain the stability of the dispersed state, and the stability of image repetition is lacking. Even in the case of microencapsulation, the cell size is set to the microcapsule level, and such defects are apparently difficult to appear, and no essential problem is solved.

In contrast to the electrophoretic method utilizing the behavior in a solution as described above, recently, a solution is not used, and an electric field is applied between two types of particles having different colors and different charging polarities. There is also proposed a device for displaying by adhering to substrates in directions different from each other. Since this method is a dry method as compared with the electrophoresis method, it has an advantage that the movement resistance of particles is small and the response speed is fast. The operation mechanism of such a dry display device is that a mixture of two kinds of particles having different colors and charged polarities is sandwiched between electrode plates, and a voltage is applied to the electrode plates to generate an electric field between the electrode plates to polarize them. It is used as a display element by flying differently charged particles of different directions in different directions.

The operation mechanism of such an image display device is such that a mixture of two particles having different colors and charged polarities is sandwiched between electrode plates and a voltage is applied to the electrode plates to generate an electric field between the electrode plates. It is used as a display element by causing charged particles having different polarities to fly in different directions. Here, the force applied to the particles may be a force that attracts each other due to the Coulomb force between the particles, an electric image force with the electrode plate, an intermolecular force, a liquid bridge force, and gravity. Due to the relative relationship between the total force and the force exerted on the particles by the electric field, the particles themselves fly when the force by the electric field exceeds.

[0006] In particular, the charge amount of the particles themselves is the most important parameter when controlling the force generated by the electric field and the adhesion between the particles or the electrode plate. Further, when considering the fine particles as a display element, it is essential that the color tone is white and black particles so that the contrast becomes clear. Therefore, as fine particles for display media,
It is necessary to have sufficient white / blackness and to maintain a sufficient amount of charge.

First, regarding the chargeability, it is usually considered that the chargeability is expressed by the charge characteristic of the main material constituting the fine particles. Particularly, when a polar resin such as PMMA, nylon, styrene, or fluorine is used, high charging characteristics can be obtained. In addition, in order to accelerate the charging time, that is, the time to reach high chargeability or saturated charge,
A method of internally adding a charge control material has also been proposed. In the realization of white and black, ordinary resin fine particles have a clear color, and as they are, the hiding ratio is low and they do not function as a display medium. Therefore, in order to achieve a predetermined degree of blackness and whiteness, it is conceivable to enclose a dye or a pigment in the fine particles or to further coat the surface with a resin containing a coloring material. However, if the surface is coated, the charging ability of the resin, which is the main material, is hidden, and it is difficult to obtain sufficient charging characteristics. Further, when the dye is internally added, the coloring property is good but the hiding property is poor,
It cannot exert a sufficient effect as a display medium.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been earnestly studied in view of the above circumstances, and in a dry image display device of a type in which particles fly, it is easy to control the degree of coloring and the amount of charge, An object of the present invention is to provide an image display particle and a device capable of stably obtaining a good image with sufficient contrast.

[0009]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the present inventors have found that after kneading and pulverizing a resin, a colorant and, if necessary, a charge control agent, the surface is smoothed. By using the modified particles, it is possible to obtain particles with a uniform charge amount distribution without uneven distribution of charge, and it is easy to control the degree of coloring and the charge amount, and a satisfactory image with stable contrast can be obtained stably. The present invention has been completed and the present invention has been completed.

That is, the present invention provides the following image display particles and apparatus. 1. In an image display device in which one or more kinds of particles are enclosed between opposing substrates, at least one of which is transparent, and the particles are caused to fly and move to display an image, the particles include a resin, a colorant, and, if necessary, a charge control agent. Particles for image display, which are particles obtained by smoothing the surface of primary particles that have been kneaded and ground. 2. The particles for image display according to 1 above, which use particles obtained by instantaneously applying high heat to the primary particles to finely melt and smooth the surface. 3. The particles for image display according to the above 1, which use particles obtained by smoothing the surface of the primary particles with mechanical stress. 4. An image display device in which one or more kinds of particles are enclosed between opposing substrates, at least one of which is transparent, and an electric field is applied to the particles from two kinds of electrodes having different potentials to cause the particles to fly and move to display an image, An image display device using particles obtained by smoothing the surface of primary particles obtained by kneading and pulverizing a resin and a colorant as the particles.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The image display device of the present invention is an image displaying one or more kinds of particles between opposing substrates, at least one of which is transparent, and flying and moving the particles by Coulomb force or the like. It is a display device. In such a dry image display device, as shown in FIG. 1, two or more types of particles having different colors are moved in the direction perpendicular to the substrate, and as shown in FIG. There is a display method by moving the substrate in a direction parallel to the substrate, and it can be applied to any of them, but it is preferable to apply the former method from the viewpoint of stability. FIG. 3 is an explanatory view showing the structure of the image display device, which is formed by the substrate 1, the substrate 2 and the particles 3 facing each other, and the partition wall 4 is provided as necessary.

Regarding the substrate, at least one of the substrate 1 and the substrate 2 is a transparent substrate from which the color of particles can be confirmed from the outside of the device, and a material having a high visible light transmittance and a high heat resistance is suitable. Whether or not the image display device is flexible is appropriately selected depending on the application. For example, for an application such as electronic paper, a flexible material, a mobile phone, a PDA, and a display of a portable device such as a notebook computer are used. An inflexible material is used.

Examples of the substrate material include polyethylene terephthalate, polyether sulfone, polyethylene,
Examples thereof include polymer sheets such as polycarbonate and inorganic sheets such as glass and quartz. Substrate thickness is 2-5
000 μm, preferably 5 to 1000 μm is suitable, and when it is too thin, it becomes difficult to maintain strength and uniformity of spacing between substrates, and when it is too thick, sharpness as a display function and deterioration of contrast occur. It lacks flexibility in paper applications.

In the electrostatic image display device of the present invention, the electrode may be provided on the substrate or may not be provided on the substrate. When no electrode is provided, an electrostatic latent image is given to the outer surface of the substrate, and an electric field generated according to the electrostatic latent image attracts or repels predetermined charged colored particles to the substrate. , The particles arranged corresponding to the electrostatic latent image are visually recognized from the outside of the display device through the transparent substrate. The electrostatic latent image is formed by a method for transferring and forming an electrostatic latent image on a substrate of an electrostatic image display device of the present invention, which is performed by a normal electrophotographic system using an electrophotographic photoreceptor, or an ion flow. There is a method such as directly forming an electrostatic latent image on the substrate.

When an electrode is provided, particles of a predetermined charged color are attracted or repelled by an electric field generated at each electrode position on the substrate by inputting an external voltage to the electrode portion, thereby forming an electrostatic latent image. The correspondingly arranged particles are visually recognized from the outside of the display device through the transparent substrate. The electrode is made of a transparent and patternable conductive material on a transparent substrate, and is made of a metal such as aluminum, silver, nickel, copper or gold, or a transparent conductive metal oxide such as ITO, conductive tin oxide or conductive zinc oxide. Sputtering method, vacuum evaporation method, CV
A thin film formed by the method D, a coating method, or the like, or a conductive agent mixed with a solvent or a synthetic resin binder and applied is used.

Examples of the conductive agent include cationic polymer electrolytes such as benzyltrimethylammonium chloride and tetrabutylammonium perchlorate, anionic polymer electrolytes such as polystyrene sulfonate and polyacrylate, and conductive zinc oxide and tin oxide. Indium oxide fine powder or the like is used. In addition, the electrode thickness may be 3 to 1000 nm, preferably 5 to 400 nm, as long as the conductivity can be secured and the light transmittance is not hindered. Although a transparent electrode material can be used on the counter substrate, a non-transparent electrode material such as aluminum, silver, nickel, copper, or gold can also be used. In this case, the external voltage may be applied by superimposing DC or AC on it. It is preferable to form an insulating coat layer on each electrode so that the charges of the charged particles do not escape. In this coat layer, it is particularly preferable to use a resin having a positive charging property for the negatively charged particles and a resin having a negative charging property for the positively charged particles because it is difficult for the charge of the particles to escape.

It is preferable that the partition walls are provided on the four circumferences of each display element. The partition walls can be provided in two parallel directions. As a result, excessive movement of particles in the direction parallel to the substrate can be prevented, durability repeatability and memory retention can be assisted, and the distance between the substrates can be made uniform and reinforced to increase the strength of the image display plate. The method for forming the partition wall is not particularly limited, for example, a screen printing method in which paste is applied in a predetermined position using a screen plate, or a partition material having a desired thickness is solidly coated on a substrate to form a partition wall. After coating the resist pattern only on the part to be left on the partition material, a blasting material is sprayed to remove the partition material other than the partition material by sandblasting, or a resist pattern is formed on the substrate using a photosensitive resin. , A lift-off method (additive method) in which the resist is removed after the paste is embedded in the resist recesses, or a photosensitive resin composition containing a partition material is applied onto the substrate, and a desired pattern is obtained by exposure and development. Paste method or a mold forming method of forming barrier ribs by applying a paste containing a barrier rib material on the substrate, and then pressure-bonding and pressure-molding a mold or the like having irregularities. Various methods are employed. Further applying the mold forming method, using the relief pattern provided by the photosensitive resin composition as a mold,
The relief stamping method is also adopted.

The average particle size of the particles is preferably 0.1 to 50 μm, particularly preferably 1 to 30 μm. When the particle size is smaller than this range, the charge density of the particles is too large and the image force on the electrode or the substrate is too strong, and the memory property is good, but the followability when the electric field is reversed becomes poor. On the contrary, if the particle size is larger than this range, the followability is good, but the memory property becomes poor.

The method of negatively or positively charging the particles is not particularly limited, but a method of charging the particles such as a corona discharge method, an electrode injection method and a friction method is used. The absolute value of the charge amount of the particles is preferably in the range of 10 to 100 μC / g, particularly 2
0-60 μC / g is preferable. If the absolute value of the charge amount is smaller than this range, the response speed to changes in the electric field becomes low and the memory property also becomes low. If the absolute value of the charge amount is larger than this range, the image force on the electrode or the substrate is too strong and the memory property is good, but the followability when the electric field is reversed becomes poor.
Since the particles need to retain their charged electric charge,
Insulating particles of 10 ¹⁰ Ω · cm or more are preferable, especially 10 ¹² Ω.
-Insulating particles of cm or more are preferable.

In order to make the particles spherical, a method for producing fine particles by a polymerization method has been proposed. According to this, substantially spherical particles can be obtained. However, in this case, it is difficult to enclose the pigment in the particles, and the operation such as special treatment of the pigment to increase the affinity between the monomer and the pigment at the time of polymerization becomes very complicated. In addition, the degree of freedom in producing fine particles is extremely narrowed due to a large limitation due to polymerization conditions such as the mixing ratio and type of pigment. The same adverse effects occur with respect to the inclusion of the charge control material, and the polymerization method is a solution-based operation, so it cannot be said to be the optimum method from the industrial viewpoint such as generation of waste liquid.

Therefore, according to the present invention, as described above, in an image display device for displaying an image by causing particles to fly and move by Coulomb force or the like, as the particles, a resin, a colorant and, if necessary, a charge control agent are kneaded and pulverized. The particles obtained by smoothing the surface of the secondary particles are used. The primary particles are prepared by first mixing a resin as a main material, a colorant (pigment), and optionally a charge control material with a Henschel mixer or the like, and kneading the mixture with a plastomill or a twin-screw kneading extruder. Dispersed in the resin. Next, it is pulverized to a few mm with a pulverizer such as a hammer mill or a chopper mill, and further pulverized with a fine pulverizer such as a jet mill to obtain fine particles for a display medium.

Since the primary particles thus obtained are obtained by pulverization, they have an irregular shape. For this reason, the electric charge is concentrated especially in the angular portion, and non-uniform charging occurs in the particles. Further, when such a state occurs, the Coulomb force between the electrode plate and the fine particles becomes extremely large locally, which is a great obstacle to low voltage driving of the image display device. Furthermore, since each particle has various shapes, the distribution of the charge amount is broadened as a whole, and the movement of the particles varies, which hinders display on the display.

Therefore, in the present invention, the sharp corners of the amorphous particles obtained by kneading and crushing are smoothed by post-treatment. As a method for smoothing, a method in which particles are diffused by an air flow and a high temperature is instantaneously applied to melt only an extremely surface (Saffusion System: Nippon Pneumatic Co., Ltd.), or a corner portion by mechanical stress is used. (Mechanofusion system: Hosokawa Micron Co., Ltd., hybridizer: Nara Machine Co., Ltd.) and the like. By smoothing in this way, it is possible to obtain particles having a uniform charge amount distribution without uneven distribution of charges. Further, since the image display particles of the present invention are basically obtained by kneading and pulverizing, the degree of coloring and the amount of charge can be easily controlled.

Examples of the resin used in the image display particles of the present invention include urethane resin, urea resin, acrylic resin, polyester resin, acrylic urethane resin,
Acrylic urethane silicone resin, acrylic urethane fluororesin, acrylic fluororesin, silicone resin, acrylic silicone resin, epoxy resin, polystyrene resin, styrene acrylic resin, polyolefin resin, butyral resin, vinylidene chloride resin, melamine resin, phenol resin, fluororesin, Polycarbonate resin, polysulfone resin, polyether resin, polyamide resin and the like can be mentioned, especially from the standpoint of controlling the adhesion with the substrate,
Acrylic urethane resin, acrylic silicone resin, acrylic fluororesin, acrylic urethane silicone resin, acrylic urethane fluororesin, fluororesin, and silicone resin are suitable. It is also possible to mix two or more kinds.

As the colorant used in the image display particles of the present invention, various organic or inorganic pigments and dyes of various colors as shown below can be used. Examples of black pigments include carbon black, copper oxide, manganese dioxide, aniline black and activated carbon. Examples of the yellow pigment include yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, benzidine yellow GR, Examples include quinoline yellow rake, permanent yellow NCG, and tartrazine rake. Examples of orange pigments include red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, induslen brilliant orange RK, benzidine orange G and induslen brilliant orange GK.

Examples of red pigments include red iron oxide, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, resole red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine. Rake B, Alizarin Rake, Brilliant Carmine 3B, etc. Examples of purple pigments include manganese purple, fast violet B, and methyl violet lake.
Examples of blue pigments include dark blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated compound, fast sky blue, and indanthrene blue BC. Examples of green pigments include chrome green, chrome oxide, pigment green B, malachite green lake, and final yellow green G.

Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc and alumina white. Further, various dyes such as basic dyes, acid dyes, dispersion dyes and direct dyes include nigrosine, methylene blue, rose bengal, quinoline yellow and ultramarine blue. These colorants can be used alone or in combination.

In the particles for image display of the present invention, the charge control agent used as necessary is not particularly limited as long as it is soluble in a solvent and can control charge, and it is commercially available as a charge control agent. Those that have been used are preferably used. Examples thereof include a nigrosine compound, a resin acid-modified azine, a resin acid-modified azine compound, a quaternary ammonium salt, a salicylic acid-based metal complex, a phenol-based condensate, a metal-containing azo compound, and a triphenylmethane derivative. Further, by selecting a charge control agent, it is possible to dye in black or dark purple simultaneously with charge control, and it is possible to obtain fine particles for black display. That is, in the above, the nigrosine compound, the resin acid-modified azine compound, the resin acid-modified azine compound, and the metal-containing azo compound can be dyed with a solution in which the powder is dyed.

Specifically, as a negative charge control agent, a salicylic acid metal complex, a metal-containing azo dye, a metal-containing (including metal ion or metal atom) oil-soluble dye, a quaternary ammonium salt compound, a calixarene compound, Examples thereof include a boron-containing compound (boronic acid boron complex) and a nitroimidazole derivative. Examples of positive charge control agents include nigrosine dyes, triphenylmethane compounds, quaternary ammonium salt compounds, polyamine resins, and imidazole derivatives. In addition, nitrogen-containing cyclic compounds such as pyridine and derivatives and salts thereof, various organic pigments, resins containing fluorine, chlorine, nitrogen and the like can also be used as the charge control agent.

The distance between the transparent substrate and the counter substrate in the image display device of the present invention is adjusted so that particles can fly and move and the contrast can be maintained, but it is usually adjusted to 10 to 5000 μm, preferably 30 to 500 μm. The particle loading is
It is preferable that the volume is 10 to 80%, preferably 20 to 70% of the space volume between the substrates.

The image display device of the present invention is an image display unit of a mobile device such as a notebook computer, a PDA, a mobile phone, an electronic book, an electronic paper such as an electronic newspaper, a signboard,
It is used for posters, bulletin boards such as blackboards, copiers, rewritable paper as a substitute for printer paper, calculators, image display parts of home appliances, card image display parts such as point cards.

[0032]

EXAMPLES Next, the present invention will be described more specifically by showing examples. However, the present invention is not limited to the following examples. In each Example and Comparative Example,
The average particle diameter and the charge amount were measured as follows.

(1) Average particle size Particle size distribution measuring machine (Mastersizer 2000, Malvern
Each particle was placed in instruments Ltd.) and the particle size distribution was measured. The average particle size (μm) is defined as the numerical value in μm in which 50% of the particles are larger and 50% are smaller by the attached software. Also, the particle size distribution Sp
an is shown in the following formula. Particle size distribution Span = (d (0.9) -d (0.1)) / d (0.5) (However, 50% of the particles in d (0.5) are larger than 50%
Is the numerical value expressed in μm as the particle size is smaller than this, d
(0.1) is the particle size where the ratio of particles below this is 10% is μm
And d (0.9) represents the particle size of 90% of the particles below this in μm. )

(2) Charge distribution E-spart analyzer (Hosokawa Micron Corp.)
Was used to measure the charge amount distribution.

(3) Evaluation of Display Function By applying 500 V to the prepared display device and inverting the polarity, black / white display was repeated. For the evaluation of the display function, a black and white display is used for the reflection image densitometer (R
D918, manufactured by Macbeth). Here, the point at which the density did not change even when the voltage was increased was defined as the image density, and the voltage at that time was defined as the drive voltage. The contrast ratio is the ratio of the reflection density during black display to the reflection density during white display (= reflection density during black display / reflection density during white display). Further, the unevenness at the time of full-screen display was judged according to the following criteria. ◯: The entire surface is colored in almost 100% black / white without unevenness. Δ: Complete black and white inversion cannot be performed, and there are spots. X: The display is a mixture of black and white.

Example 1 White particles (negatively chargeable) were polystyrene resins (Toyostyrol: MW-1-301, Toyo Styrene Co., Ltd.).
And colorants (titanium oxide: CR50, Ishihara Sangyo Co., Ltd.)
, 20 phr) and charge control agent (Bontron E8
4, Hodogaya Chemical Co., Ltd., 5 phr) was kneaded and extruded with a twin-screw kneading extruder at a set temperature of 180 ° C., formed into pellets with a cutter, and roughly crushed to a diameter of about 1 mm with a chipper mill. Then, it was finely pulverized with a jet mill to an average particle size of about 5 μm, and a classifier was used to adjust the average particle size to 5.1 μm and the particle size span = 0.7. The surface of the obtained primary particles was smoothed by using a Suffusion system (SFS-03: manufactured by Nippon Pneumatic Co., Ltd.) at a hot air temperature of 450 ° C. Black particles (positively chargeable) are acrylic resin (Delpet 80NH: Asahi Kasei Corp.) and colorant (Carbon Black # 45, Mitsubishi Carbon Corp.).
5 phr) and charge control agent (Bontron N21,
Similarly, using Hodogaya Chemical Co., Ltd. product, 5 phr, kneading and extruding were performed, and pulverization and surface smoothing were performed. The display device was created as follows. That is, a pair of glass substrates provided with indium oxide electrodes (thickness: 50 nm) having a thickness of about 500 Å were adjusted with a spacer so that the distance between them was 100 μm, and the white particles and the black particles were sealed between the glass substrates. The periphery of the glass substrate was adhered with an epoxy adhesive to form a display device. The mixing ratios of the white particles and the black particles were the same weight, and the filling ratio of the particles between the glass substrates was adjusted to be 50% by volume. Table 1 shows the evaluation results of the particle characteristics and the display function.

Example 2 In Example 1, the surface of the primary particles was smoothed by mechanofusion (AMS-LAB, Hosokawa Micron Corp.).
The image display particles were prepared in the same manner as in Example 1 except that the particles were used. First evaluation results of particle characteristics and display function
Shown in the table.

Reference Example White particles (negatively chargeable) were titanium oxide (lipophilic) obtained by dissolving 0.5 parts by weight of AIBN (azobisisobutynitrile) in 100 parts by weight of styrene monomer and coupling the solution. CR50, Ishihara Sangyo Co., Ltd., 20 phr) and a charge control agent (Bontron E84, Hodogaya Chemical Co., Ltd., 5 phr) are dispersed to obtain a liquid of 10
Double the amount of 0.5% surfactant (sodium lauryl sulfate)
After being dispersed in an aqueous solution for suspension polymerization, filtered and dried, white particles of 5 to 10 μm were obtained using a pulverizing classifier (FM-120: made by Nippon Pneumatic). Black particles (positively chargeable) are 0.5 parts by weight of AIB in 80 parts by weight of tertiary butyl methacrylate monomer and 20 parts by weight of 2- (dimethylamino) ethyl methacrylate monomer.
N (azobisisobutyronitrile) is dissolved, and a colorant (Carbon Black # 45, manufactured by Mitsubishi Carbon Co., Ltd.,
5 phr) and a charge control agent (Bontron N21, 5 phr by Hodogaya Chemical Co., Ltd.)
Double the amount of 0.5% surfactant (sodium lauryl sulfate)
After being dispersed in an aqueous solution for suspension polymerization, filtered and dried, black particles of 5 to 10 μm were obtained using a pulverizing classifier (FM-120: made by Nippon Pneumatic). A display device was prepared in the same manner as in Example 1 using the above particles. Table 1 shows the evaluation results of the particle characteristics and the display function.

Comparative Example 1 In Example 1, the surface of the primary particles was not smoothed,
The primary particles were directly used as image display particles. Table 1 shows the evaluation results of the particle characteristics and the display function.

[0040]

[Table 1]

[0041]

The image display device of the present invention is an image display device in which one or more kinds of particles are enclosed between a transparent substrate and a counter substrate, and the particles fly and move to display an image. After kneading and pulverizing the charge control agent according to the above, by using particles having a smoothed surface, it is possible to obtain particles having a uniform charge amount distribution without uneven distribution of charges, and it is possible to control the coloring degree and the charge amount. An image that is easy and has a sufficient contrast can be stably obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a display system in an electrostatic image display device of the present invention.

FIG. 2 is an explanatory diagram showing a display system in the electrostatic image display device of the present invention.

FIG. 3 is an explanatory diagram showing a structure of an electrostatic image display device of the present invention.

[Explanation of symbols]

1, 2: substrate 3: Particle 4: Partition wall

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] August 26, 2002 (2002.8.2)
6)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction content]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device capable of repeatedly displaying and erasing an image as particles fly and move by utilizing Coulomb force and the like , and particles for image display thereof.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

First, regarding the chargeability, it is usually considered that the chargeability is expressed by the charge characteristic of the main material constituting the fine particles. Particularly, when a polar resin such as PMMA, nylon, styrene, or fluorine is used, high charging characteristics can be obtained. In addition, in order to accelerate the charging time, that is, the time to reach high chargeability or saturated charge,
A method of internally adding a charge control agent has also been proposed. In the realization of white and black, ordinary resin fine particles have a clear color, and as they are, the hiding ratio is low and they do not function as a display medium. Therefore, in order to achieve a predetermined degree of blackness and whiteness, it is conceivable to enclose a dye or a pigment in the fine particles or to further coat the surface with a resin containing a coloring material. However, if the surface is coated, the charging ability of the resin, which is the main material, is hidden, and it is difficult to obtain sufficient charging characteristics. Further, when the dye is internally added, the coloring property is good but the hiding property is poor,
It cannot exert a sufficient effect as a display medium.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

Therefore, according to the present invention, as described above, in an image display device for displaying an image by causing particles to fly and move by Coulomb force or the like, as the particles, a resin, a colorant and, if necessary, a charge control agent are kneaded and pulverized. The particles obtained by smoothing the surface of the secondary particles are used. The primary particles are prepared by first mixing a resin as a main material, a colorant (pigment), and optionally a charge control agent with a Henschel mixer or the like, and kneading them using a plastomill or a twin-screw kneading extruder. Dispersed in the resin. Next, it is pulverized to a few mm with a pulverizer such as a hammer mill or a chopper mill, and further pulverized with a fine pulverizer such as a jet mill to obtain fine particles for a display medium.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

Therefore, in the present invention, the sharp corners of the amorphous particles obtained by kneading and crushing are smoothed by post-treatment. As a method for smoothing, a method in which particles are diffused by an air flow and a high temperature is instantaneously applied to melt only an extremely surface (Saffusion System: Nippon Pneumatic Co., Ltd.), or a corner portion by mechanical stress is used. how to smoothing (mechanofusion system: Hosokawa Micron Co., hybrida homogenizer: Nara machinery Co.), and the like. By smoothing in this way, it is possible to obtain particles having a uniform charge amount distribution without uneven distribution of charges. Further, since the image display particles of the present invention are basically obtained by kneading and pulverizing, the degree of coloring and the amount of charge can be easily controlled.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

As the colorant used in the image display particles of the present invention, various organic or inorganic pigments and dyes of various colors as shown below can be used. Examples of black pigments include carbon black, copper oxide, manganese dioxide, aniline black and activated carbon. The yellow pigment, chrome yellow, zinc yellow, cadmium yellow, yellow iron oxide, mineral Fast Yellow, nickel titanium yellow, nave Louis Yellow, Naphthol Yellow S, Hansa Yellow G, Hansa yellow 10G, benzidine yellow G, benzidine yellow GR , Quinoline yellow rake, permanent yellow NCG, tartrazine rake, etc. Examples of orange pigments include red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, induslen brilliant orange RK, benzidine orange G and induslen brilliant orange GK.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

Examples of red pigments include red iron oxide, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, resole red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine. Rake B, Alizarin Rake, Brilliant Carmine 3B, etc. The violet pigments, manganese violet, Fast violet B, and methyl violet lake.
Examples of blue pigments include dark blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated compound, fast sky blue, and indanthrene blue BC. Examples of green pigments include chrome green, chrome oxide, pigment green B, malachite green lake, and final yellow green G.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

Specifically, as a negative charge control agent, a salicylic acid metal complex, a metal-containing azo dye, a metal- containing (including metal ion or metal atom) oil-soluble dye, a quaternary ammonium salt compound, a calixarene compound, Examples thereof include a boron-containing compound (boronic acid boron complex) and a nitroimidazole derivative. As positive charge control agents include nigrosine dyes, tri Fe Nirumetan compounds, quaternary ammonium salt compound, polyamine resin, imidazole derivatives, and the like. In addition, nitrogen-containing cyclic compounds such as pyridine and derivatives and salts thereof, various organic pigments, resins containing fluorine, chlorine, nitrogen and the like can also be used as the charge control agent.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

Example 1 White particles (negatively chargeable) were polystyrene resins (Toyostyrol: MW-1-301, Toyo Styrene Co., Ltd.).
And colorants (titanium oxide: CR50, Ishihara Sangyo Co., Ltd.)
, 20 phr) and charge control agent (Bontron E8
4, Hodogaya Chemical Co., Ltd., 5 phr) was kneaded and extruded with a twin-screw kneading extruder at a set temperature of 180 ° C., formed into pellets with a cutter, and roughly crushed to a diameter of about 1 mm with a chipper mill. Then, it was finely pulverized with a jet mill to an average particle size of about 5 μm, and a classifier was used to adjust the average particle size to 5.1 μm and the particle size span = 0.7. The surface of the obtained primary particles was smoothed by using a Suffusion system (SFS-03: manufactured by Nippon Pneumatic Co., Ltd.) at a hot air temperature of 450 ° C. Black particles (positively chargeable) are acrylic resin (Delpet 80NH: Asahi Kasei Corp.) and colorant (Carbon Black # 45, Mitsubishi Carbon Corp.).
5 phr) and charge control agent (Bontron N21,
Similarly, using Hodogaya Chemical Co., Ltd. product, 5 phr, kneading and extruding were performed, and pulverization and surface smoothing were performed. The display device was manufactured as follows. That is, a pair of glass substrates provided with indium oxide electrodes (thickness: 50 nm) having a thickness of about 500 Å are adjusted with a spacer so that the distance between them is 100 μm, and the white particles and the black particles are sealed between the glass substrates. The periphery of the glass substrate was adhered with an epoxy adhesive to form a display device. The mixing ratios of the white particles and the black particles were the same weight, and the filling ratio of the particles between the glass substrates was adjusted to be 50% by volume. Table 1 shows the evaluation results of the particle characteristics and the display function.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

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Example 2 In Example 1, the surface of the primary particles was smoothed by mechanofusion (AMS-LAB, Hosokawa Micron Corp.).
Image display particles were produced in the same manner as in Example 1 except that the above was used. First evaluation results of particle characteristics and display function
Shown in the table.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

Reference Example White particles (negatively chargeable) were titanium oxide (lipophilic) obtained by dissolving 0.5 parts by weight of AIBN (azobisisobutynitrile) in 100 parts by weight of styrene monomer and coupling the solution. CR50, Ishihara Sangyo Co., Ltd., 20 phr) and a charge control agent (Bontron E84, Hodogaya Chemical Co., Ltd., 5 phr) are dispersed to obtain a liquid of 10
Double the amount of 0.5% surfactant (sodium lauryl sulfate)
After being dispersed in an aqueous solution for suspension polymerization, filtered and dried, white particles of 5 to 10 μm were obtained using a pulverizing classifier (FM-120: made by Nippon Pneumatic). Black particles (positively chargeable) are 0.5 parts by weight of AIB in 80 parts by weight of tertiary butyl methacrylate monomer and 20 parts by weight of 2- (dimethylamino) ethyl methacrylate monomer.
N (azobisisobutyronitrile) is dissolved, and a colorant (Carbon Black # 45, manufactured by Mitsubishi Carbon Co., Ltd.,
5 phr) and a charge control agent (Bontron N21, 5 phr by Hodogaya Chemical Co., Ltd.)
Double the amount of 0.5% surfactant (sodium lauryl sulfate)
After dispersing in an aqueous solution, suspension polymerization, filtration and drying, 5-10 μm black particles were obtained using a pulverizing classifier (FM-120: made by Nippon Pneumatic). A display device was manufactured in the same manner as in Example 1 using the above particles. Table 1 shows the evaluation results of the particle characteristics and the display function.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Norio Nihei             3-5-5 Ogawahigashi-cho, Kodaira-shi, Tokyo (72) Inventor Hajime Kitano             3-5-5 Ogawahigashi-cho, Kodaira-shi, Tokyo (72) Inventor Yoshitomo Masuda             3-5-28 Shinmeidai, Hamura-shi, Tokyo

Claims (4)

[Claims] 1. An image display device for enclosing one or more kinds of particles between opposing substrates, at least one of which is transparent, and flying the particles to display an image. The charge control agent was kneaded and crushed 1
A particle for image display, which is a particle obtained by smoothing the surface of a secondary particle. 2. The particles for image display according to claim 1, wherein particles obtained by momentarily applying high heat to the primary particles to finely melt and smooth the surface are used. 3. The particles for image display according to claim 1, wherein particles obtained by smoothing the surface of the primary particles with mechanical stress are used. 4. One or more kinds of particles are enclosed between opposing substrates, at least one of which is transparent, and an electric field is applied to the particles from two kinds of electrodes having different electric potentials to fly and move the particles to display an image. In the image display device, particles obtained by smoothing the surface of primary particles obtained by kneading and crushing a resin and a colorant as the particles are used.