JP2005352145A - Method of manufacturing image display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an image display panel for forming a fine rugged pattern on the surface of a substrate or the like and for decreasing the driving voltage of an image display medium. <P>SOLUTION: In the method of manufacturing an image display panel by sealing an image display medium 3 between substrates 1, 2 at least one of which is transparent and applying an electric field on the image display medium 3 to move the image display medium 3 to display an image, the inner surfaces of the substrates 1, 2 are treated by a wet blasting method to form a fine rugged pattern 21 on the surfaces of the substrates 1, 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an image display panel in which an image display medium is sealed between opposing substrates at least one of which is transparent, an electric field is applied to the image display medium, and the image display medium is moved to display an image. It is.

  2. Description of the Related Art Conventionally, image display devices using techniques such as an electrophoresis method, an electrochromic method, a thermal method, and a two-color particle rotation method have been proposed as image display devices that can replace liquid crystal (LCD).

  Compared to LCDs, these conventional technologies have advantages such as a wide viewing angle close to that of ordinary printed materials, low power consumption, and a memory function. It is considered as a technology that can be used for mobile phones, and is expected to expand to image display for mobile terminals, electronic paper, and the like. Particularly recently, an electrophoretic method in which a dispersion liquid composed of dispersed particles and a colored solution is encapsulated and disposed between opposing substrates has been proposed and is expected.

  However, the electrophoresis method has a problem that the response speed becomes slow due to the viscous resistance of the liquid because the particles migrate in the liquid. Furthermore, since particles with high specific gravity such as titanium oxide are dispersed in a solution with low specific gravity, it is easy to settle, and it is difficult to maintain the stability of the dispersed state, and there is a problem of lack of image repetition stability. . Even when microencapsulation is performed, the cell size is set to the microcapsule level, and the above-described drawbacks are hardly made to appear, and the essential problems are not solved at all.

  On the other hand, a method in which conductive particles and a charge transport layer are incorporated into a part of a substrate without using a solution is proposed instead of an electrophoresis method using behavior in a solution (see, for example, Non-Patent Document 1). ). However, the structure is complicated because the charge transport layer and further the charge generation layer are arranged, and it is difficult to inject the charges into the conductive particles.

As one method for solving the various problems described above, an image display medium is sealed between opposing substrates at least one of which is transparent, an electric field is applied to the image display medium, and the image display medium is moved to display an image. An image display device is known.
趙 Kuniori and three others, “New Toner Display Device (I)”, July 21, 1999, Annual Meeting of the Imaging Society of Japan (83 times in total) “Japan Hardcopy'99” Proceedings, p.249-252

  In the image display panel constituting the above-described conventional image display device, the drive voltage is inevitably high because of the configuration, and thus there is a high demand for developing a technique for reducing the drive voltage. One of the causes for the high drive voltage is that particles or powder fluid used as an image display medium adhere to the surface of a substrate or the like. In order to solve this problem, it is conceivable to provide a concavo-convex shape on the surface of a substrate or the like, but the conventional method cannot provide a good concavo-convex shape.

  That is, in the case of forming an uneven shape on the surface of a substrate or the like by a method such as sand blasting, a mold pressing method, or a mold transfer method, there is a problem that it is difficult to form a fine structure, particularly a submicron level uneven shape. In addition, when forming an uneven shape on the surface of a substrate or the like by applying a resin in which fluorine resin particles are mixed and dispersed, there is a problem that it is difficult to form a thin film with high uniformity and strength reliability. . Furthermore, when an electrode is provided on the substrate and an insulating film such as a resin is provided on the surface of the electrode, problems such as an increase in electrical resistance have occurred.

  An object of the present invention is to solve the above-mentioned problems and to provide a method for manufacturing an image display panel capable of forming a fine fine uneven shape on the surface of a substrate or the like and thereby reducing the driving voltage. Is.

  An image display panel manufacturing method of the present invention is an image in which an image display medium is sealed between opposing substrates at least one of which is transparent, an electric field is applied to the image display medium, and the image display medium is moved to display an image. In the method for manufacturing a display panel, a fine concavo-convex shape is formed on the substrate surface by processing at least one substrate inner surface using a wet blast method.

  Moreover, as a suitable example of the manufacturing method of the image display panel of the present invention, when an electrode is provided on the inner surface of the substrate, (1) by depositing the electrode on the inner surface of the substrate after wet blasting, Transferring the fine irregularities on the substrate surface to the electrode surface, forming fine irregularities on the exposed substrate inner surface and the electrode surface, and (2) exposing the substrate inner surface after depositing the electrode on the substrate inner surface. In addition, fine concavo-convex shapes may be formed on the exposed substrate inner surface and electrode surface by wet blasting the electrode surface.

  Furthermore, as a preferred example of the method for manufacturing an image display panel of the present invention, when an electrode and an insulating film covering a part of the electrode are provided on the substrate inner surface, (1) the substrate inner surface is subjected to wet blasting The electrode is formed, then the insulating film is formed, and the fine irregularities on the substrate surface are transferred to the electrode surface and the insulating film surface, so that the exposed substrate inner surface and the exposed electrode surface and insulating film surface are fine. Forming irregular shapes, (2) Forming electrodes on the inner surface of the substrate, and wet blasting the exposed inner surface of the substrate and the electrode surface to form fine irregular shapes on the exposed inner surface of the substrate and the electrode surface Then, by forming an insulating film and transferring the fine uneven shape on the electrode surface to the insulating film surface, the fine uneven shape on the exposed substrate inner surface and the exposed electrode surface and insulating film surface And (3) forming an electrode and an insulating film on the substrate inner surface, and wet-blasting the exposed substrate inner surface and the exposed electrode surface and insulating film surface to expose the exposed substrate inner surface and the exposed surface. In some cases, fine irregularities are formed on the surface of the electrode and the insulating film.

  Furthermore, as a preferable example of the method for producing an image display panel of the present invention, the formed fine uneven shape has a surface roughness Ra of 1 nm to 300 nm, the image display medium is a particle group, and The image display medium may be a powder fluid.

  According to the present invention, the contact inner surface (adhesive force) between the inner surface of the substrate and the image display medium is formed by forming the fine uneven shape on the inner surface of the substrate by processing the inner surface of the substrate using the wet blast method. As a result, the drive voltage of the image display panel can be reduced.

  First, a basic configuration of an image display panel that is an object of the manufacturing method of the present invention will be described. In the image display panel used in the present invention, an electric field is applied to an image display medium (particle group or powder fluid) sealed between two opposing substrates. Along with the applied electric field direction, the image display medium charged at a low potential toward the high potential side is attracted by the force of the electric field or the Coulomb force, and is charged at a high potential toward the low potential side. The image display medium is attracted by a force due to an electric field, a Coulomb force, or the like, and the image display medium reciprocates due to a change in the direction of the electric field caused by a potential change, thereby displaying an image. Therefore, it is necessary to design the image display panel so that the image display medium moves uniformly and can maintain stability during repetition or storage. Here, as the force applied to the particles constituting the image display medium, in addition to the force attracted by the Coulomb force between the particles, the electric image force with the electrode and the substrate, the intermolecular force, the liquid cross-linking force, gravity and the like can be considered. .

An example of an image display panel which is an object of the manufacturing method of the present invention will be described with reference to FIGS. 1 (a) and (b) to FIGS. 3 (a) and 3 (b).
In the example shown in FIGS. 1A and 1B, two or more kinds of particles 3 having different colors (here, white particles 3W and black particles 3B) are applied according to the electric field applied from the outside of the substrates 1 and 2. Then, the black particles 3B are moved vertically to the substrates 1 and 2 so that the observer can visually recognize the black particles 3B, or the white particles 3W are visually recognized by the observer. In the example shown in FIG. 1B, in addition to the example shown in FIG. 1A, partition walls 4 are provided, for example, in a lattice shape between the substrates 1 and 2 to define display cells.
In the example shown in FIGS. 2A and 2B, two or more kinds of particles 3 having different colors (here, white particles 3W and black particles 3B are shown) are provided on the substrate 1 and the electrode 5 provided on the substrate 1, respectively. Depending on the electric field generated by applying a voltage between the electrode 6 and the electrode 6, the substrate is moved perpendicularly to the substrates 1 and 2 so that the black particles 3B are visually recognized by the observer, or a white display is performed. The particle 3W is visually recognized by an observer and white display is performed. In the example shown in FIG. 2B, in addition to the example shown in FIG. 2A, partition walls 4 are provided, for example, in a lattice form between the substrates 1 and 2 to define display cells.
In the example shown in FIGS. 3A and 3B, a voltage is applied between the electrode 5 and the electrode 6 provided on the substrate 1 with one kind of color particle 3 (here, white particle 3W). The white particles 3W are moved in the direction parallel to the substrates 1 and 2 in accordance with the electric field generated by the white light display, and the white color is displayed by the observer, or the color of the electrode 6 or the substrate 1 is visually recognized by the observer. Thus, the color of the electrode 6 or the substrate 1 is displayed. In the example shown in FIG. 3B, in addition to the example shown in FIG. 3A, a partition 4 is provided between the substrates 1 and 2 to form a display cell, for example.
The above description can be similarly applied to the case where the white particles 3W are replaced with the white powder fluid and the black particles 3B are replaced with the black powder fluid.

The features of the method for manufacturing an image display panel according to the present invention will be described below.
The feature of the image display panel manufacturing method of the present invention is that the surface exposed to the space constituted by the substrates 1 and 2, specifically, the substrate inner surface when constituted only by the substrate, and the substrate and electrodes If it consists of the substrate inner surface and the electrode surface exposed to the space, and the substrate inner surface and the insulating film surface exposed to the space if the substrate inner surface and the electrode surface exposed to the space, fine unevenness by wet blasting This is the point where the shape is provided.

  Here, the wet blasting method is a polishing method in which a polishing material, a solvent, and a compressed gas are mixed from a blast gun and ejected to process a substrate or the like. In the wet blast method, since the fluidity of the abrasive is improved by using a solvent, it is possible to use an abrasive having a finer particle diameter than the sand blast method. Therefore, it is possible to produce a finer uneven shape. Moreover, since it is a physical processing method, either glass or resin can be used as the substrate to be processed. Furthermore, since it is a method of directly processing a substrate or the like, the reliability with respect to strength is higher than that of a chemical method.

  FIG. 4 is a view for explaining an example of the wet blasting method in the method for manufacturing an image display panel of the present invention. In the example shown in FIG. 4, 11 is an injection nozzle, and 12 is a supply pipe for supplying a treatment liquid to the injection nozzle 11. As an apparatus for performing such wet blasting, an apparatus manufactured by Macau Corporation can be used. In the example shown in FIG. 4, a mixed liquid of water and abrasive is jetted from a jet nozzle 11 to a substrate 1 (2) having an ITO electrode 5 (6) through a supply pipe 12 at a high pressure with compressed air. The surface of the exposed substrate 1 (2) and the surface of the ITO electrode 5 (6) are roughened to form a fine uneven shape.

  The main wet blasting conditions include air pressure: 0.2 MPa, abrasive: alumina (particle size: 4 μm), and substrate: glass. As an abrasive other than alumina, glass, zirconia, resin, or the like can be used. The shape of the abrasive is spherical or polygonal. When it is desired to wet blast only a part of the substrate, a mask is used on the substrate. The surface roughness Ra of the substrate after the wet blast treatment cannot be generally limited depending on the type and size of the image display medium used, but the surface roughness Ra is preferably in the range of 1 nm to 300 nm. Here, when Ra is less than 1 nm, the unevenness is too fine and the contact area between the particle and the substrate does not decrease so much, and when Ra exceeds 300 nm, the unevenness is too rough and the particles get stuck in the unevenness. As a result, the contact area increases.

  Next, a specific method for forming a fine uneven shape by a wet blast method will be described. FIGS. 5A and 5B are diagrams for explaining an example of an application method of wet blasting when electrodes are formed on a substrate. In the following example, the substrate 1 and the electrode 5 are described as examples, but the same applies to the substrate 2 and the electrode 6. In the example shown in FIG. 5A, when the electrode 5 is provided on the substrate 1, the surface of the substrate 1 is wet blasted, and then the electrode 5 is formed, thereby forming the fine uneven shape on the surface of the substrate 1. As a result, the fine uneven portions 21 are formed on the exposed surface of the substrate 1 and the surface of the electrode 5. In the example shown in FIG. 5B, when the electrode 5 is provided on the substrate 1, the electrode 5 is formed on the surface of the substrate 1, and then the exposed surface of the substrate 1 and the surface of the electrode 5 are wet blasted. Thus, fine uneven portions 21 are formed on the exposed surface of the substrate 1 and the surface of the electrode 5.

  FIGS. 6A to 6C are diagrams for explaining an example of an application method of wet blasting in the case where an electrode and an insulating film are formed on a substrate, respectively. In the example shown in FIG. 6A, when the electrode 5 and the insulating film 22 covering the electrode 5 are provided on the substrate 1, the electrode 1 is formed after the substrate 1 is wet blasted, and then the insulating film 22 is formed. A fine uneven portion 21 is formed on the exposed surface of the substrate 1 and the surface of the insulating film 22 by forming a film and transferring the fine uneven shape on the surface of the substrate 1 to the surface of the electrode 5 and the surface of the insulating film 22. . In the example shown in FIG. 6B, when the electrode 5 and the insulating film 22 covering the electrode 5 are provided on the substrate 1, the electrode 5 is formed on the substrate 1, and the exposed surface of the substrate 1 and the electrode 5 are formed. The surface of the substrate 5 is wet-blasted to form fine irregularities on the exposed surface of the substrate 1 and the surface of the electrode 5, and then the insulating film 22 is formed. By transferring to the surface, fine uneven portions 21 are formed on the exposed surface of the substrate 1 and the surface of the insulating film 22. In the example shown in FIG. 6C, when the electrode 5 and the insulating film 22 covering the electrode 5 are provided on the substrate 1, the electrode 5 and the insulating film 23 are formed on the substrate 1, and the exposed substrate 1 is exposed. By finely blasting the surface, the surface of the exposed electrode, and the surface of the insulating film 22, the fine uneven portion 21 is formed on the exposed surface of the substrate 1, the exposed surface of the electrode, and the surface of the insulating film 22.

Actually, in the configuration shown in FIG. 2B, glass substrates are used as the substrates 1 and 2 and ITO electrodes are used as the electrodes 5 and 6, and the substrates 1 and 2 exposed in the space between the substrates 1 and 2 are used. A fine uneven portion 21 having a predetermined surface roughness Ra is provided on the surface and the surfaces of the electrodes 5 and 6 by wet blasting, and a white particle group having an average particle size of 9.0 μm and an average particle size of 7.5 μm are provided as an image display medium. An image display panel filled with a black particle group was prepared, and the display characteristics of the panel were examined.
The item evaluated this time is the threshold voltage. The threshold voltage is a voltage at which the contrast of the display image starts to change when the voltage applied to the display panel is increased from zero. As the threshold voltage is lower, the image display medium can be driven at a lower voltage. Conversely, as the threshold voltage is higher, a higher voltage is required for driving.
Then, the influence of the surface roughness Ra on the threshold voltage on the panel was examined, and the result as shown in FIG. 8 was obtained. In FIG. 8, a broken line shows an estimated extrapolation line. The threshold voltage standard value in FIG. 8 is a value obtained by converting the threshold voltage when the ITO surface is not wet-blasted, and therefore the uneven shape is not formed, to 100. In this case, the surface roughness Ra of the ITO surface was approximately 0 mm. From the results of FIG. 8, it can be seen that the smaller the surface roughness Ra, the smaller the contact area (adhesive force) between the image display medium and the substrate or electrode, and thus the threshold voltage decreases as the surface roughness Ra decreases. As a result, according to the present invention, it is understood that the fine uneven portion 21 having a small surface roughness Ra (preferably in the range of Ra 1 to 300 nm) can be obtained by wet blasting, so that the driving voltage of the panel can be lowered.

  Hereinafter, each member which comprises the image display panel used as the object of this invention is demonstrated.

  As for the substrate, at least one substrate is the transparent substrate 2 from which the color of the image display medium can be confirmed from the outside of the display panel, and a material having high visible light transmittance and good heat resistance is preferable. The substrate 1 may be transparent or opaque. Examples of substrate materials include polymer sheets such as polyethylene terephthalate, polyethersulfone, polyethylene, polycarbonate, polyimide, and acrylic, flexible materials such as metal sheets, and flexible materials such as glass and quartz. There are no inorganic sheets. The thickness of the substrate is preferably 2 to 5000 μm, more preferably 5 to 2000 μm. If it is too thin, it will be difficult to maintain the strength and the uniform spacing between the substrates, and if it is thicker than 5000 μm, it will be mounted on a thin image display device. Is inconvenient.

  Electrode forming materials for electrodes provided as necessary include metals such as aluminum, silver, nickel, copper, and gold, conductive metal oxides such as ITO, indium oxide, conductive tin oxide, and conductive zinc oxide, polyaniline , Conductive polymers such as polypyrrole and polythiophene are exemplified, and are appropriately selected and used. As a method of forming the electrode, a method of forming the above-described material into a thin film by sputtering, vacuum deposition, CVD (chemical vapor deposition), coating, or the like, or mixing a conductive agent with a solvent or a synthetic resin binder. The method of apply | coating is used. The electrode provided on the viewing side substrate needs to be transparent, but the electrode provided on the back side substrate does not need to be transparent. In any case, the above-mentioned material that is conductive and capable of pattern formation can be suitably used. Note that the electrode thickness is not particularly limited as long as the conductivity can be secured and the light transmittance is not hindered, and is preferably 3 to 1000 nm, preferably 5 to 400 nm. The material and thickness of the electrode provided on the back side substrate are the same as those of the electrode provided on the viewing side substrate described above, but need not be transparent. In this case, the external voltage input may be superimposed with direct current or alternating current.

  The shape of the partition 4 provided as necessary is optimally set depending on the type of the image display medium involved in the display, and is not limited in general, but the width of the partition is 2 to 100 μm, preferably 3 to 50 μm. Is adjusted to 10 to 500 μm, preferably 10 to 200 μm. In forming the partition walls, a both-rib method in which ribs are formed on each of the opposing substrates and then bonded, and a one-rib method in which ribs are formed only on one substrate are conceivable. In the present invention, any method is preferably used.

  As shown in FIG. 9, the display cells formed by the partition walls made up of these ribs are exemplified by a square shape, a triangular shape, a line shape, a circular shape, and a hexagonal shape as viewed from the substrate plane direction. The shape and the mesh shape are exemplified. It is better to make the portion corresponding to the cross section of the partition wall visible from the display side (the area of the frame portion of the display cell) as small as possible, and the sharpness of the image display increases. Here, examples of the method for forming the partition include a screen printing method, a sand blast method, a photolithography method, and an additive method. Of these, the photolithography method using a resist film is preferably used.

  Next, the particles used as the image display medium used in the image display panel that is the subject of the present invention will be described. The particles can contain a charge control agent, a colorant, an inorganic additive, and the like, if necessary, in the resin as the main component, as in the conventional case. Examples of resins, charge control agents, colorants, and other additives will be given below.

  Examples of the resin 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, and two or more kinds can be mixed. In particular, acrylic urethane resin, acrylic silicone resin, acrylic fluororesin, acrylic urethane silicone resin, acrylic urethane fluororesin, fluororesin, and silicone resin are suitable from the viewpoint of controlling the adhesive force with the substrate.

  The charge control agent is not particularly limited. Examples of the negative charge control agent include salicylic acid metal complexes, metal-containing azo dyes, metal-containing oil-soluble dyes (including metal ions and metal atoms), and quaternary ammonium salt systems. Examples thereof include compounds, calixarene compounds, boron-containing compounds (benzyl acid boron complexes), and nitroimidazole derivatives. Examples of the positive charge control agent include nigrosine dyes, triphenylmethane compounds, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives, and the like. In addition, metal oxides such as ultrafine silica, ultrafine titanium oxide, ultrafine alumina, nitrogen-containing cyclic compounds such as pyridine and derivatives and salts thereof, various organic pigments, resins containing fluorine, chlorine, nitrogen, etc. are also charged. It can also be used as a control agent.

  As the colorant, various organic or inorganic pigments and dyes as exemplified below can be used.

Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon and the like.
Examples of blue colorants include C.I. I. Pigment blue 15: 3, C.I. I. Pigment Blue 15, Bituminous Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Metal-free Phthalocyanine Blue, Phthalocyanine Blue Partial Chlorides, Fast Sky Blue, Indanthrene Blue BC and the like.
Examples of red colorants include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, risor red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, Alizarin Lake, Brilliant Carmine 3B, C.I. I. Pigment Red 2 etc.

Yellow colorants include chrome yellow, zinc yellow, cadmium yellow, yellow iron oxide, mineral first yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, C.I. I. Pigment Yellow 12 etc.
Examples of green colorants include chrome green, chromium oxide, pigment green B, C.I. I. Pigment Green 7, Malachite Green Lake, Final Yellow Green G, etc.
Examples of the orange colorant include red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. I. Pigment Orange 31 etc.
Examples of purple colorants include manganese purple, first violet B, and methyl violet lake.
Examples of white colorants include zinc white, titanium oxide, antimony white, and zinc sulfide.

  Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white. Examples of various dyes such as basic, acidic, disperse, and direct dyes include nigrosine, methylene blue, rose bengal, quinoline yellow, and ultramarine blue.

Examples of inorganic additives include titanium oxide, zinc white, zinc sulfide, antimony oxide, calcium carbonate, lead white, talc, silica, calcium silicate, alumina white, cadmium yellow, cadmium red, cadmium orange, titanium yellow, Examples include bitumen, ultramarine blue, cobalt blue, cobalt green, cobalt violet, iron oxide, carbon black, manganese ferrite black, cobalt ferrite black, copper powder, and aluminum powder.
These pigments and inorganic additives can be used alone or in combination. Of these, carbon black is particularly preferable as the black pigment, and titanium oxide is preferable as the white pigment.

  The particles of the present invention preferably have an average particle diameter d (0.5) in the range of 0.1 to 50 μm and are uniform and uniform. If the average particle diameter d (0.5) is larger than this range, the display is not clear, and if it is smaller than this range, the cohesive force between the particles becomes too large, which hinders the movement of the particles.

Furthermore, in the present invention, regarding the particle size distribution of each particle, the particle size distribution Span represented by the following formula is set to less than 5, preferably less than 3.
Span = (d (0.9) −d (0.1)) / d (0.5)
(However, d (0.5) is a numerical value expressed in μm that the particle size is 50% larger than this and 50% smaller than this, and d (0.1) is a particle whose ratio is 10% or less. (Numerical value expressed in μm, and d (0.9) is a numerical value expressed in μm for a particle diameter of 90% or less.)
By keeping Span within a range of 5 or less, the size of each particle is uniform, and uniform particle movement becomes possible.

  Furthermore, regarding the correlation between the particles, the ratio of d (0.5) of the particles having the minimum diameter to d (0.5) of the particles having the maximum diameter among the used particles is set to 50 or less, preferably 10 or less. It is essential. Even if the particle size distribution Span is reduced, particles with different charging characteristics move in opposite directions, so that the particle size is close to each other and each particle can be easily moved in the opposite direction by the equivalent amount. This is within this range.

The particle size distribution and the particle size can be obtained from a laser diffraction / scattering method or the like. When laser light is irradiated onto particles to be measured, a light intensity distribution pattern of diffracted / scattered light is spatially generated, and this light intensity pattern has a corresponding relationship with the particle diameter, so that the particle diameter and particle diameter distribution can be measured. .
Here, the particle size and particle size distribution in the present invention are obtained from a volume-based distribution. Specifically, using a Mastersizer2000 (Malvern Instruments Ltd.) measuring instrument, put particles into a nitrogen stream and use the attached analysis software (software based on volume-based distribution using Mie theory). The diameter and particle size distribution can be measured.

  Next, the powder fluid used as the image display medium in the image display panel which is the subject of the present invention will be described. In addition, about the name of the powder fluid using the particle | grains for image display media of this invention, the present applicant has acquired the right of "electronic powder fluid (trademark)."

  The “powder fluid” in the present invention is a substance in an intermediate state of both fluid and particle characteristics that exhibits fluidity by itself without borrowing the force of gas or liquid. For example, liquid crystal is defined as an intermediate phase between a liquid and a solid, and has fluidity that is a characteristic of liquid and anisotropy (optical properties) that is a characteristic of solid (Heibonsha: Encyclopedia) . On the other hand, the definition of particle is an object with a finite mass even if it is negligible, and is said to be affected by gravity (Maruzen: Physics Encyclopedia). Here, even in the case of particles, there are special states of gas-solid fluidized bed and liquid-solid fluids. When gas is flowed from the bottom plate to the particles, upward force is applied to the particles according to the velocity of the gas. Is a gas-solid fluidized bed that is in a state where it can easily flow when it balances with gravity, and it is also called a liquid-solid fluidized state that is fluidized by the fluid (ordinary) Company: Encyclopedia). As described above, the gas-solid fluidized bed body and the liquid-solid fluid are in a state of using a gas or liquid flow. In the present invention, it has been found that a substance in a state of fluidity can be produced specifically without borrowing the force of such gas and liquid, and this is defined as powder fluid.

  That is, the pulverulent fluid in the present invention is in an intermediate state having both the characteristics of particles and liquid, as in the definition of liquid crystal (liquid and solid intermediate phase), and is the characteristic of the above-mentioned particles. It is a substance that is extremely unaffected and exhibits a unique state with high fluidity. Such a substance can be obtained in an aerosol state, that is, a dispersion system in which a solid or liquid substance is stably suspended as a dispersoid in a gas, and the solid substance is used as a dispersoid in the image display device of the present invention. Is.

The image display panel which is the object of the present invention exhibits high fluidity in an aerosol state in which solid particles are stably suspended as a dispersoid as an image display medium, for example, as an image display medium between opposing substrates at least one of which is transparent The powder fluid is sealed, and such powder fluid can be easily and stably moved by Coulomb force or the like by applying a low voltage.
As described above, for example, the powder fluid used in the present invention is a substance in an intermediate state between fluid and particles, which exhibits fluidity by itself without borrowing the force of gas or liquid. This powder fluid can be in an aerosol state in particular, and in the image display device of the present invention, a solid substance is used in a state of relatively stably floating as a dispersoid in the gas.

The range of the aerosol state is preferably such that the apparent volume of the pulverized fluid when it is floated is twice or more that when it is not suspended, more preferably 2.5 times or more, and particularly preferably 3 times or more. Although an upper limit is not specifically limited, It is preferable that it is 12 times or less.
If the apparent volume of the pulverized fluid is less than twice that of the unfloating state, it is difficult to control the display, and if it is more than 12 times, the powder fluid will be overloaded when sealed in the device. Inconvenience in handling occurs. The apparent volume at the maximum floating time is measured as follows. That is, the powdered fluid is put into a closed container that allows the powdered fluid to permeate, and the container itself is vibrated or dropped to create a maximum floating state, and the apparent volume at that time is measured from the outside of the container. Specifically, in a container with a lid (trade name: iBoy: manufactured by ASONE Co., Ltd.) having a diameter (inner diameter) of 6 cm and a height of 10 cm, a powder fluid equivalent to 1/5 of the volume as a powder fluid when not floating. And set the container on a shaker, and shake at a distance of 6 cm at 3 reciprocations / sec for 3 hours. The apparent volume immediately after stopping shaking is the apparent volume at the maximum floating time.

Moreover, in this invention, what the time change of the apparent volume of a powder fluid satisfy | fills following Formula is preferable.
V ₁₀ / V ₅ > 0.8
Here, V ₅ represents an apparent volume (cm ³ ) 5 minutes after the maximum floating time, and V ₁₀ represents an apparent volume (cm ³ ) 10 minutes after the maximum floating time. In the image display device of the present invention, the time change V ₁₀ / V ₅ of the apparent volume of the powder fluid is preferably larger than 0.85, particularly preferably larger than 0.9. When V ₁₀ / V ₅ is 0.8 or less, it becomes the same as when ordinary so-called particles are used, and it becomes impossible to ensure the effect of high-speed response and durability as in the present invention.

  Moreover, the average particle diameter (d (0.5)) of the particulate material constituting the powder fluid is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and particularly preferably 0.9 to 8 μm. . If it is smaller than 0.1 μm, it is difficult to control the display, and if it is larger than 20 μm, the display is not clear. The average particle diameter (d (0.5)) of the particulate material constituting the powder fluid is the same as d (0.5) in the next particle diameter distribution Span.

The particle substance constituting the powder fluid preferably has a particle size distribution Span represented by the following formula of less than 5, more preferably less than 3.
Particle size distribution Span = (d (0.9) -d (0.1)) / d (0.5)
Here, d (0.5) is a numerical value expressed in μm of the particle diameter that 50% of the particulate material constituting the powder fluid is larger than this and 50% is smaller than this, and d (0.1) is less than this. A numerical value in which the ratio of the particle substance constituting the powder fluid is 10%, expressed in μm, and d (0.9) is the particle diameter in which the particulate substance constituting the powder fluid is 90% μm It is a numerical value expressed by By setting the particle size distribution Span of the particulate material constituting the powder fluid to 5 or less, the sizes are uniform and uniform powder fluid movement becomes possible.

  The particle size distribution and particle size of the particulate material constituting the above powder fluid can be obtained from a laser diffraction / scattering method or the like. When laser light is irradiated to the powder fluid to be measured, a light intensity distribution pattern of diffracted / scattered light is generated spatially, and this light intensity pattern has a corresponding relationship with the particle diameter, so the particle diameter and particle diameter distribution are measured. it can. This particle size and particle size distribution are obtained from a volume-based distribution. Specifically, using a Mastersizer2000 (Malvern Instruments Ltd.) measuring machine, the powdered fluid was introduced into the nitrogen stream, and the attached analysis software (software based on volume reference distribution using Mie theory) Measurements can be made.

  Preparation of powder fluid can be done by kneading and pulverizing the necessary resin, charge control agent, colorant, and other additives, or by polymerization from monomers, and adding existing particles to resin, charge control agent, colorant, and other It may be coated with an agent. Hereinafter, the resin, charge control agent, colorant, and other additives constituting the powder fluid will be exemplified.

  Examples of the resin include urethane resin, acrylic resin, polyester resin, urethane-modified acrylic resin, silicone resin, nylon resin, epoxy resin, styrene resin, butyral resin, vinylidene chloride resin, melamine resin, phenol resin, fluorine resin, etc. Two or more types can also be mixed. In particular, acrylic urethane resin, acrylic urethane silicone resin, acrylic urethane fluororesin, urethane resin, and fluororesin are preferable from the viewpoint of controlling the adhesive force with the substrate.

  Examples of charge control agents include quaternary ammonium salt compounds, nigrosine dyes, triphenylmethane compounds, imidazole derivatives and the like in the case of imparting positive charges, and metal-containing azo compounds in the case of imparting negative charges. Examples thereof include dyes, salicylic acid metal complexes, and nitroimidazole derivatives.

  As the colorant, various organic or inorganic pigments and dyes as exemplified below can be used.

Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon and the like.
Examples of blue colorants include C.I. I. Pigment blue 15: 3, C.I. I. Pigment Blue 15, Bituminous Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Metal-free Phthalocyanine Blue, Phthalocyanine Blue Partial Chlorides, Fast Sky Blue, Indanthrene Blue BC and the like.
Examples of red colorants include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, risor red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, Alizarin Lake, Brilliant Carmine 3B, C.I. I. Pigment Red 2 etc.

Yellow colorants include chrome yellow, zinc yellow, cadmium yellow, yellow iron oxide, mineral first yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, C.I. I. Pigment Yellow 12 etc.
Examples of green colorants include chrome green, chromium oxide, pigment green B, C.I. I. Pigment Green 7, Malachite Green Lake, Final Yellow Green G, etc.
Examples of the orange colorant include red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. I. Pigment Orange 31 etc.
Examples of purple colorants include manganese purple, first violet B, and methyl violet lake.
Examples of white colorants include zinc white, titanium oxide, antimony white, and zinc sulfide.

  Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white. Examples of various dyes such as basic, acidic, disperse, and direct dyes include nigrosine, methylene blue, rose bengal, quinoline yellow, and ultramarine blue.

Examples of inorganic additives include titanium oxide, zinc white, zinc sulfide, antimony oxide, calcium carbonate, lead white, talc, silica, calcium silicate, alumina white, cadmium yellow, cadmium red, cadmium orange, titanium yellow, Examples include bitumen, ultramarine blue, cobalt blue, cobalt green, cobalt violet, iron oxide, carbon black, manganese ferrite black, cobalt ferrite black, copper powder, and aluminum powder.
These pigments and inorganic additives can be used alone or in combination. Of these, carbon black is particularly preferable as the black pigment, and titanium oxide is preferable as the white pigment.

However, even if such a material is kneaded and coated without any ingenuity, a powder fluid that shows an aerosol state cannot be produced. The production method of the powder fluid showing the aerosol state is not clear, but is exemplified as follows.
First, it is appropriate to fix inorganic fine particles having an average particle diameter of 20 to 100 nm, preferably 20 to 80 nm, to the surface of the particulate material constituting the powder fluid. Furthermore, it is appropriate that the inorganic fine particles are treated with silicone oil. Here, examples of the inorganic fine particles include silicon dioxide (silica), zinc oxide, aluminum oxide, magnesium oxide, cerium oxide, iron oxide, and copper oxide. The method of fixing the inorganic fine particles is important. For example, using a hybridizer (manufactured by Nara Machinery Co., Ltd.) or mechanofusion (manufactured by Hosokawa Micron Co., Ltd.) or the like, under certain limited conditions (for example, treatment time ), A powder fluid showing an aerosol state can be produced.
In this invention, the powder fluid adjusted in this way can be used as an image display medium.

  The charge amount of the image display medium naturally depends on the measurement conditions, but the charge amount of the image display medium in the image display panel is almost the initial charge amount, the contact with the partition wall, the contact with the substrate, and the charge decay with the elapsed time. In particular, it was found that the saturation value of the charging behavior of the image display medium is the dominant factor.

  As a result of intensive studies, the present inventors have found that by measuring the charge amount of the image display medium using the same carrier particles in the blow-off method, it is possible to evaluate the range of the appropriate charging characteristic value of the image display medium. .

Furthermore, in the present invention, it is important to manage the gas in the gap surrounding the image display medium between the substrates, which contributes to improved display stability. Specifically, it is important that the relative humidity at 25 ° C. is 60% RH or less, preferably 50% RH or less, and more preferably 35% RH or less with respect to the humidity of the gas in the gap.
1A, 1B, 3A, and 3B, the gap portion is defined by the electrodes 5 and 6 and the image display medium (particles) from the portion sandwiched between the opposing substrate 1 and substrate 2. It refers to the gas portion in contact with the so-called image display medium, excluding the group or powdered fluid 3) occupied portion, the partition 4 occupied portion (if present), and the device seal portion.
The gas in the gap is not limited as long as it is in the humidity region described above, but dry air, dry nitrogen, dry argon, dry helium, dry carbon dioxide, dry methane, and the like are preferable. This gas needs to be sealed in the apparatus so that the humidity is maintained. For example, the image display medium is filled and the substrate is assembled in a predetermined humidity environment. It is important to apply a sealing material and a sealing method to prevent the above.

The distance between the substrates in the image display panel provided in the image display device of the present invention is not limited as long as the image display medium can be moved and the contrast can be maintained, but is usually adjusted to 10 to 500 μm, preferably 10 to 200 μm. .
The volume occupation ratio of the image display medium in the space between the opposing substrates is preferably 5 to 70%, more preferably 5 to 60%. If it exceeds 70%, the movement of the image display medium is hindered. If it is less than 5%, the contrast tends to be unclear.

  An image display device using particles obtained by the production method of the present invention includes display units of mobile devices such as notebook computers, PDAs, mobile phones, handy terminals, electronic papers such as electronic books and electronic newspapers, signboards, posters, and blackboards. Suitable for bulletin boards such as billboards, calculators, home appliances, automobile supplies, card displays such as point cards and IC cards, electronic advertisements, electronic POPs, electronic price tags, electronic musical scores, and display parts for RF-ID devices Used.

(A), (b) is a figure which shows an example of the panel for image displays used as the object of the manufacturing method of this invention, respectively. (A), (b) is a figure which shows the other example of the panel for image displays used as the object of the manufacturing method of this invention, respectively. (A), (b) is a figure which shows the further another example of the panel for image displays used as the object of the manufacturing method of this invention, respectively. It is a figure for demonstrating an example of the wet blasting method in the manufacturing method of the image display panel of this invention. (A), (b) is a figure for demonstrating an example of the application method of the wet blast process in the case of forming an electrode on a board | substrate, respectively. (A)-(c) is a figure for demonstrating an example of the application method of the wet blast process in the case of forming an electrode and an insulating film on a board | substrate, respectively. It is a graph which shows the relationship between contrast and an image display medium drive voltage. It is a graph which shows the relationship between threshold voltage specification value and board | substrate inner surface roughness Ra. It is a figure which shows an example of the shape of the partition in the image display panel used as the object of the manufacturing method of this invention.

Explanation of symbols

1, 2 Substrate 3 Image display medium (particle group or powder fluid)
3W white particles (white powder fluid)
3B Black particles (black powder fluid)
4 Partitions 5 and 6 Electrodes 11 Injection nozzles 12 Supply pipes 21 Fine irregularities 22 Insulating film

Claims (9)

  In a method for manufacturing an image display panel in which an image display medium is sealed between opposing substrates at least one of which is transparent, an electric field is applied to the image display medium, and the image display medium is moved to display an image, a wet blast method is used. A method for producing an image display panel, comprising: forming a fine concavo-convex shape on a substrate inner surface by processing at least one substrate inner surface.   When an electrode is provided on the inner surface of the substrate, the electrode is deposited on the inner surface of the substrate after wet blasting, thereby transferring the fine irregularities on the substrate surface to the electrode surface, and exposing the exposed inner surface of the substrate and the electrode surface. The manufacturing method of the image display panel of Claim 1 which forms fine uneven | corrugated shape in a.   When an electrode is provided on the inner surface of the substrate, after forming the electrode on the inner surface of the substrate, the exposed inner surface of the substrate and the electrode surface are wet blasted to form a fine uneven shape on the exposed inner surface of the substrate and the electrode surface. The manufacturing method of the image display panel of Claim 1 formed.   When an electrode and an insulating film covering a part of the electrode are provided on the inner surface of the substrate, an electrode is formed after wet blasting the inner surface of the substrate, and then an insulating film is formed. The method for manufacturing an image display panel according to claim 1, wherein fine irregularities are formed on the exposed substrate inner surface and insulating film surface by transferring the film to the electrode surface and the insulating film surface.   In the case where an electrode and an insulating film covering a part of the electrode are provided on the inner surface of the substrate, the electrode is formed on the inner surface of the substrate and exposed by wet blasting the exposed inner surface of the substrate and the electrode surface. By forming fine irregularities on the substrate inner surface and electrode surface, and then forming an insulating film, and transferring the minute irregularities on the electrode surface to the insulating film surface, the exposed substrate inner surface and the exposed electrode surface and insulation The manufacturing method of the panel for image displays of Claim 1 which forms fine uneven | corrugated shape in the film | membrane surface.   When an electrode and an insulating film covering a part of the electrode are provided on the substrate inner surface, the electrode and the insulating film are formed on the substrate inner surface, and the exposed substrate inner surface and the exposed electrode surface and insulating film surface are formed. 2. The method for manufacturing an image display panel according to claim 1, wherein fine concavo-convex shapes are formed on the exposed substrate inner surface, the exposed electrode surface, and the insulating film surface by wet blasting.   The method for producing an image display panel according to any one of claims 1 to 6, wherein the formed fine irregularities have a surface roughness Ra of 1 nm to 300 nm.   The method for producing an image display panel according to claim 1, wherein the image display medium is a particle group.   The method for manufacturing an image display panel according to claim 1, wherein the image display medium is a powder fluid.

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