JP2007178881A - Information display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information display panel capable of performing homogeneous information display of high quality by eliminating attenuation of electric charges that particles of a display media have and an increase in sticking force of the particles for display medium to a substrate. <P>SOLUTION: The information display panel is constituted so that at least one or more kinds of display medium charged between two substrates at least one of which is transparent, and moving the display medium is moved to display information of an image etc. by applying an electric field to the display medium, wherein particles 11 for display medium constituting at least the one kind of display medium are compound particles having external additive particles 12 stuck on particle surfaces, and the external additive particles sticking on the particle surfaces contain particles having electric semiconductor characteristics on their surfaces. Semiconductor materials on the particle surfaces are preferably hole transporting materials or electron transporting materials. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an information display panel for displaying information such as an image by moving a display medium by enclosing a display medium between two substrates, at least one of which is transparent, and applying an electric field to the display medium. It is.

  2. Description of the Related Art Conventionally, information display devices using techniques such as electrophoresis, electrochromic, thermal, and two-color particle rotation have been proposed as information display devices that 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 information 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. In addition, 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 that the stability of repeated information display is lacking. ing. 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.

As a method for solving the above-described problems, a display medium is sealed between two substrates, at least one of which is transparent, and an electric field is applied to the display medium, whereby the display medium is moved to display information such as an image. An information display panel to be displayed is known.
趙 Kuniaki 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 information display panel described above, the force acting on the electric field is higher due to the relative relationship between the total force acting on the display medium particles, for example, Coulomb force, and the force acting on the display medium particles by the electric field. In this case, the display medium itself moves. Thereby, the display medium particles charged by the applied electric field adhere to the substrate surface, and if an electric field is applied in a predetermined pattern, the display medium can function.

  Here, when long-term continuous use or long-term storage is performed, for example, the particles for display media having opposite polarities are aggregated, the charge of the particles for display media is attenuated, or due to friction There has been a problem that overcharging occurs or the surface of the display medium particles wears to increase the adhesion area with the substrate and increase the adhesion force due to intermolecular force. These all suppress the movement of the particles for the display medium, and there is a problem that it becomes impossible to display uniform and high-quality information.

  The object of the present invention is to eliminate the above-mentioned problems and eliminate the charge attenuation of the display medium particles and the increase in the adhesion force of the display medium particles to the substrate, and display homogeneous and high-quality information. An information display panel is to be provided.

  In the information display panel of the present invention, at least one type of display medium is sealed between two opposing substrates, at least one of which is transparent, and the display medium is moved by applying an electric field to the display medium. In the information display panel for displaying the display medium, the particles for display medium constituting at least one type of display medium are composite particles having external additive particles attached to the particle surface, and the external additive attached to the particle surface The particles include particles having semiconductor electrical characteristics on the surface.

  In addition, as a suitable example of the information display panel of the present invention, the relationship between the particle diameter d1 of particles having semiconductor electrical characteristics on the surface used for the external additive particles and the particle diameter d2 of the display medium particles is as follows. It is 1/1000 ≦ d1 / d2 ≦ 1/10, and the particles having the electrical characteristics of the semiconductor occupy the surface with respect to the total weight of the external additive particles adhering to the surface of the display medium particle constituting the display medium. Of the external additive particles adhering to the surface of the display medium particles constituting the display medium, the ratio of the ratio is 0.5% to 5%. It may be a hole transporting material or an electron transporting material, and the display medium particles constituting the display medium may have at least optical reflectance and charging characteristics.

  In the present invention, at least one type of display medium is sealed between two opposing substrates, at least one of which is transparent, and information such as an image is displayed by moving the display medium by applying an electric field to the display medium. In the panel for display, the particles for display medium constituting at least one type of display medium are composite particles having external additive particles attached to the particle surface, and the external additive particles attached to the particle surface By including particles that have electrical characteristics of semiconductors, it is possible to eliminate the charge attenuation of display medium particles and increase the adhesion of display medium particles to the substrate, and display information that is homogeneous and high-quality. Panel can be obtained.

  First, the basic configuration of the information display panel of the present invention will be described. In the information display panel of the present invention, an electric field is applied to a display medium sealed between two opposing substrates. Along with the applied electric field direction, the charged display medium is attracted by the electric field force or Coulomb force, etc., and the moving direction of the display medium is changed by changing the electric field direction by switching the potential, thereby displaying information such as an image. Is made. Therefore, it is necessary to design an information display panel so that the display medium can move uniformly and maintain the stability at the time of display rewriting or continuous display of information. Here, as the force applied to the particles constituting the display medium, in addition to the force attracting each other by the Coulomb force between the particles, an electric mirror image force between the electrode and the substrate, an intermolecular force, a liquid cross-linking force, gravity and the like can be considered.

  An example of an information display panel that is an object 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, at least two kinds of display media 3 (here, white display medium particles 3Wa) having at least one kind of particles and having different optical reflectance and charging characteristics. A white display medium 3W composed of a group of particles and a black display medium 3B composed of a group of particles 3Ba for black display medium) are perpendicular to the substrates 1 and 2 according to the electric field applied from the outside of the substrates 1 and 2. The black display medium 3B is visually recognized by the observer and black display is performed, or the white display medium 3W is visually recognized by the observer and white display is performed. In the example shown in FIG. 1B, in addition to the example shown in FIG. 1A, a partition 4 is provided between the substrates 1 and 2, for example, in the form of a lattice to form a cell. In addition, in FIG. 1B, the partition in front is omitted.

  In the example shown in FIGS. 2A and 2B, at least two or more types of display media 3 (here, white display medium particles 3Wa) having different optical reflectance and charging characteristics composed of at least one type of particles. Between the electrode 5 provided on the substrate 1 and the electrode 6 provided on the substrate 2 is a voltage between the electrode 5 provided on the substrate 1 and the electrode 6 provided on the substrate 2. In accordance with the electric field generated by applying, the substrate is moved perpendicularly to the substrates 1 and 2 so that the black display medium 3B is visually recognized by the observer and black display is performed, or the white display medium 3W is provided to the observer. A white display is made by visual recognition. In the example shown in FIG. 2B, a cell is formed by providing partition walls 4 between the substrates 1 and 2, for example, in a lattice shape. Further, in FIG. 2 (b), the front partition is omitted.

  In the example shown in FIGS. 3A and 3B, the display medium 3 (here, from the particle group of the particles 3Wa for white display medium) having at least an optical reflectance and a charging property composed of at least one kind of particles. The white display medium 3W) is moved in a direction parallel to the substrates 1 and 2 in accordance with the electric field generated by applying a voltage between the electrode 5 and the electrode 6 provided on the substrate 1 to display white. The medium 3W is visually recognized by the observer and white display is performed, or the color of the electrode 6 or the substrate 1 is visually recognized by the observer and the color of the electrode 6 or the substrate 1 is displayed. In the example shown in FIG. 3B, for example, a lattice-shaped partition wall 4 is provided between the substrates 1 and 2 to form a cell. Moreover, in FIG.3 (b), the partition in front is abbreviate | omitted.

  The present invention is characterized in that in the information display panel having the above-described configuration, as shown in FIG. 4, display medium particles 11 constituting at least one kind of display medium 3 are external additives on the particle surfaces. The composite particles having the particles 12 attached thereto are such that the external additive particles 12 attached to the surface of the particles 11 include particles having semiconductor electrical characteristics on the surface. Hereinafter, the background of the present invention will be described.

  As an example, a display medium composed of display medium particles (composite particles) in which external additive particles including external additive particles having electron-transporting semiconductor properties are attached to the particle surface, or hole transport to the particle surface A display medium composed of display medium particles (composite particles) to which external additive particles including external additive particles having a characteristic semiconductor property are attached is used alone depending on the configuration of the information display panel. Or use together. Further, the surfaces of the display medium particles (composite particles) constituting the display medium and at least one particle contact surface of the two opposing substrates are in an electrically rectifying contact relationship. Below, the effect at the time of using these materials is demonstrated.

  First, a contact surface between particles for display medium (composite particles) to which external additive particles including external additive particles having electric characteristics of an electron transporting semiconductor are attached and at least one particle of two opposing substrates is provided. Electrically rectifying contact. The rectifying contact is a contact in which the electric characteristics do not follow Ohm's law when a foreign substance comes into contact, and the direction of charge flow is directional. A lot of charge flows in the forward direction, and less charge flows in the reverse direction. Taking contact between a hole-transporting semiconductor and a metal as an example, a rectifying contact is obtained when the relationship between the two is Fermi level of the electron-transporting semiconductor <the work function of the metal.

  In the present invention, the rectifying effect is obtained when the Fermi level of the electron transporting semiconductor <the Fermi level of the particle contact surface. When the contact surface (substrate) with the particle has a negative potential, since it is in the reverse direction, there is little negative charge flowing into the electron transporting semiconductor particle from the contact surface, while the particle contact surface (substrate) has a positive potential. In some cases, since the forward direction is applied, the negative charge flowing from the electron-transporting semiconductor particles to the contact surface side increases, and the particles are charged positively. In the above, the case of the electron transporting semiconductor has been described as an example, but the phenomenon is exactly the same in the case of the hole transporting semiconductor, only the characteristics are reversed.

  Here, as a characteristic of the particles for display media (composite particles), it is necessary to provide the performance of accumulating charges injected with a rectifying effect inside the particles. Also, the efficiency in this charge injection must be improved. In order to achieve this, the surface of some external additive particles is made of metal or metal oxide, and an electron transporting or hole transporting semiconductor material is arranged on the surface, so that these characteristics are further improved. It will be a thing. Display media composed of two types of particles for display media (composite particles) with these electron transporting and hole transporting materials arranged on the surface are adjusted in color tone so as to improve the contrast, and facing two sheets By encapsulating between the electrode substrates and applying an electric field between the electrodes, information such as a good image can be displayed.

  For the reasons described above, it is necessary to incorporate the charge injection effect into the information display panel of the present invention. In order to obtain the charge injection effect, it is necessary to create a state in which charge injection occurs at the interface where the substrate and the display medium particles contact. In this respect, as the particles for display medium, those having improved fluidity to facilitate the movement of the particles for display medium, and external additives for the purpose of reducing the contact area with the substrate and reducing the adhesive force. Those having a structure adhered to the surface are preferably used. In this case, the substrate surface and the external additive particles are in contact with each other at the contact interface between the substrate and the display medium particles. Therefore, in order to obtain the charge injection effect described above, it is necessary to impart semiconductor characteristics to the surface of the external additive particles. Thus, the present invention has been achieved.

  The particles having semiconductor electrical characteristics on the surface that are attached to the surface of the display medium particles as some external additive particles are preferably those in which a metal or metal oxide is disposed on the surface. For example, particles composed of simple metal particles or simple metal oxides may be used. Alternatively, the surface of particles such as resin may be coated with metal or metal oxide, or the surface of particles such as resin may be partially disposed with metal or metal oxide. The thickness of the semiconductor material to be surface-covered (or partially disposed on the surface) is not particularly limited, but it is preferably a thin film when considering the charge injection efficiency, and is preferably 100 μm or less, preferably 50 μm or less, It is preferably 1 μm or less.

  The method for producing particles having the electrical characteristics of the semiconductor constituting the external additive is not particularly limited as long as the above-described electron transport property or hole transport property can be expressed. Preferably used. First, it is possible to present a method of preparing particles as a base and coating the surface with a semiconductor substance having an electron transporting property or a hole transporting property. Surface coating can be performed by vapor deposition or sputtering on the surface of the base particles, or by introducing the base particles into a dissolved or melted electron transporting or hole transporting semiconductor substance. A method of drying and solidifying, and a method of immobilizing an electron-transporting or hole-transporting semiconductor substance dissolved and melted in a particle agitating device such as a Henschel mixer after stirring. Furthermore, a method in which an electron transporting or hole transporting semiconductor material is dispersed in another resin and the particle surface based on the mixture is coated by the above-described method. As other particle manufacturing methods, a method of obtaining particles by kneading and pulverizing an electron transporting or hole transporting semiconductor material with another resin, or an electron transporting or hole transporting semiconductor material itself is used as the particles. It is also possible.

  Among these, among the particles having the electrical characteristics of the semiconductor constituting the external additive, when the surface of the base particle is coated with a semiconductor material, the surface of the base particle is coated with a metal or the like. It is preferable to use it. The base particle material is not particularly limited, and toner external additive particles used in electrophotography such as ordinary general-purpose resins, inorganic materials, and metal materials are preferably used.

  As the external additive particles adhered to the display medium particles, fine particles used as toner external additives in electrophotography and the like can be suitably used. External additive fine particles include silica, titania, alumina, zirconia, yttria, calcium oxide, magnesium oxide, barium oxide, beryllium oxide, zinc oxide, tin oxide and other metal oxide inorganic fine particles, and a crosslinked resin. Fine particles are exemplified, and silica, titania, and crosslinked resin fine particles are particularly preferably used for this purpose. The surface of the external additive particles is preferably hydrophobized. However, as a result of detailed investigations by the inventors, it is not sufficient to simply coat the surface with a hydrophobic substance (for example, dimethylpolysiloxane). The mechanism of hydrophobic expression is not particularly limited, but it is important that the hydrophilic group on the surface of the external additive particle and the hydrophobic structure form a chemically strong bond with the reactive treatment agent. I found it. This is because the interaction between the hydrophobic substance and the surface of the external additive particle is close to or less than the interaction between the surface of the external additive particle and the hydrophobic substance, or between the substrate and the hydrophobic substance. In this case, the substance is detached from the surface of the external additive particles due to collision between the display medium particles and the display medium particles due to the movement of the display medium particles, and between the display medium particles and the substrate. It is presumed that a strong cohesive force is generated by exposing the surface of the nature.

  Examples of the reactive treating agent used for the hydrophobizing treatment of the external additive particle surface include hexamethyldisilazane, octylsilane, (octyl / decyl / nonyl / (4-isopropylphenyl) / (4-tert Butylphenyl)) (trichloro / trimethoxy / triethoxy) silane, di (pentyl / hexyl / octyl / nonyl / decyl / dodecyl / (4-tert.butylphenyl) octyl / cenyl / nonenyl / -2-ethylhexyl / -3, 3-Dimethylpentyl) (dichloro / dimethoxy / diethoxy) silane, tri (isopropyl / hexyl / octyl / decyl / methyl /) (chloro / methoxy / ethoxy) silane, (dioctylmethyl / octyldimethyl / (4-isopropylphenyl) diethyl ) (Chloro / methoxy / ethoxy) silane, methyl hydrogen (poly) siloxane, methyl hydrogen (poly) siloxane and dimethyl (poly) siloxane Xanthane (random / co) (polymer / oligomer), trimethylsiloxysilicic acid, aluminum (stearate / laurate), iron stearate, acetoalkoxyaluminum diisopropylate, isopropyl (triisostearoyl / tridodecylbenzenesulfonyl) titanate, Isopropyltris (dioctylpyrophosphate) titanate, bis (dioctylpyrophosphate) (oxyacetate / ethylene) titanate, diisopropylbis (dioctylpyrophosphate) titanate, tetraisopropylbis (dioctylphosphite) titanate, tetraoctylbis (ditridecylphosphite) ) Titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl phosphite) titanate, and the like. Further, the treatment method is not particularly limited, but a solution in which the treatment agent is dispersed in a suitable solvent while stirring the external additive particles to be treated with a high-speed rotating blade type agitator such as a Henschel mixer. And after adding and dispersing the target additive particles in a solution in which the treatment agent is dispersed in an appropriate solvent, the resulting solvent is heated and dried while stirring with a mixer. A method is mentioned.

  As an example of the semiconductor material, silicon, germanium, diamond, selenium, tellurium, and the like can be given as a single semiconductor substance. Examples of the compound semiconductor include gallium arsenide, gallium phosphide, indium arsenic, gallium aluminum arsenic, gallium aluminum indium arsenide, zinc sulfide, cadmium sulfide, cadmium selenium, cadmium tellurium, silicon carbide, and the like. Furthermore, examples of the oxide semiconductor include nickel oxide (III), copper oxide (I), zinc oxide, and tin oxide (IV). In addition, nitride semiconductors, chloride semiconductors, and the like are included, and those doped therein are also included.

  Furthermore, organic semiconductors having low molecular weight include anthracene compounds, violanthrone compounds, porphyrin compounds, phthalocyanine compounds, perylene compounds, quinone compounds, azo compounds, squarylium compounds, azulenium compounds, Bililium compounds, cyanine compounds, aromatic amine compounds, aromatic diamine compounds, oxadiazole compounds, oxazole compounds, pyrazoline compounds, aromatic methane compounds, hydrazone compounds, carbazole compounds, and these And the like. In addition, examples of the high molecular organic semiconductor include polyacetylene, poly (p-phenylene), polypyrrole, polythiophene, polyaniline, poly (p-phenylene vinylene), and derivatives thereof. Furthermore, the thing which doped the impurity to the said substance is also included.

  There are no particular restrictions on the selection of these materials, but the Fermi level should be in the above range, a stable material should be selected, the cost should be low, and there should be no impact on the global environment. It is preferable to select. In the Fermi level, more efficient charge injection can be achieved when the energy gap with the Fermi level of the electrode is larger.

  The layer thickness to be coated on the surface needs to be suppressed to such an extent that the film thickness increases so much that resistance rises and the charge injection efficiency does not decrease, and is usually 10 μm or less, preferably 1 μm or less.

  In addition, the ratio of particles having semiconductor electrical characteristics on the surface to the total weight of the external additive particles adhering to the surface of the display medium particle constituting the display medium is the ratio of the external additive such as a normal metal oxide. Is used in the range of about 0.5% to 5%. Further, regarding the relationship between the particle diameters, the relationship between the particle diameter d1 of the particles constituting the external additive and the particle diameter d2 of the particles for the display medium is preferably 1/1000 ≦ d1 / d2 ≦ 1/10. . When the ratio between d1 and d2 is larger than this, the external additive cannot uniformly adhere to the surface of the display medium particles, and good characteristics cannot be obtained due to dropping off. When the ratio between d1 and d2 is smaller than this, sufficient fluidity and the effect of reducing the contact area cannot be obtained, and good characteristics cannot be obtained.

  Hereinafter, each member which comprises the information display panel of this invention is demonstrated.

  As for the substrate, at least one substrate is the transparent substrate 2 from which the color of the display medium can be confirmed from the outside of the information 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, polyethylene naphthalate, polyethersulfone, polyethylene, polycarbonate, polyimide, and acrylic, flexible materials such as metal sheets, and glass and quartz. An inorganic sheet having no flexibility is mentioned. The thickness of the substrate is preferably from 2 to 5000 μm, more preferably from 5 to 2000 μm. If it is too thin, it will be difficult to maintain the strength and the spacing uniformity between the substrates, and if it is thicker than 5000 μm, it will be a thin information display panel. Is inconvenient.

  As an electrode forming material when an electrode is provided on an information display panel as required, metals such as aluminum, silver, nickel, copper, and gold, ITO, indium oxide, conductive tin oxide, conductive zinc oxide, etc. Conductive polymers such as conductive metal oxides, polyaniline, polypyrrole, and polythiophene are exemplified and appropriately selected and used. As a method for forming an electrode, a method of forming the above-described materials 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 display surface side substrate 2 which is on the viewing side and needs to be transparent needs to be transparent, but the electrode provided on the back side substrate 1 does not need to be transparent. In any case, the above-mentioned material that can be patterned and is electrically conductive 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 1 are the same as those of the electrode provided on the display surface 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 walls 4 provided on the substrate as required is appropriately set appropriately depending on the type of display medium involved in display, the shape and arrangement of electrodes to be arranged, and is not limited in general. The height of the partition is adjusted to 100 to 100 μm, preferably 3 to 50 μm, and the height of the partition wall to 10 to 100 μm, preferably 10 to 50 μm.
In forming the partition wall, a both-rib method in which ribs are formed on each of the opposing substrates 1 and 2 and then bonded, and a single-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. 5, the cells formed by the partition walls made up of these ribs are illustrated in a square shape, a triangular shape, a line shape, a circular shape, and a hexagonal shape as viewed from the substrate plane direction. And a mesh shape. It is better to make the portion corresponding to the cross section of the partition wall visible from the display surface side (the area of the cell frame) as small as possible, and the display becomes clearer.
Examples of the method for forming the partition include a mold transfer method, a screen printing method, a sand blast method, a photolithography method, and an additive method. Any of these methods can be suitably used for the information display panel of the present invention, and among these, a photolithography method using a resist film and a mold transfer method are suitably used.

  The display medium particles of the present invention have a structure in which external additive particles having semiconductor electrical characteristics are adhered to the surface thereof, and are composed of the display medium particles as they are to form a display medium. A display medium can be combined with additive particles, or a display medium can be combined with other particles. The display medium 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 chrome yellow, 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 for display media of the present invention (hereinafter also referred to as particles) preferably have an average particle diameter d (0.5) in the range of 0.1 to 20 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 display medium.

Furthermore, in the present invention, regarding the particle size distribution of each particle, the particle size distribution Span represented by the following formula is 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 expressing the particle diameter in μm that 50% of the particles are larger than this and 50% is smaller than this, and d (0.1) is a particle in which the ratio of the smaller particles is 10%. (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 movement as a uniform display medium becomes possible.

  Furthermore, regarding the correlation between the particles, the ratio of the d (0.5) of the particles having the minimum diameter to the 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.

  The charge amount of the display medium particles naturally depends on the measurement conditions, but the charge amount of the display medium particles in the information display panel is almost the same as the initial charge amount, the contact with the partition walls, the contact with the substrate, and the elapsed time. It was found that depending on the charge decay, the saturation value of the charging behavior of the particles for the display medium is a dominant factor.

  As a result of intensive studies, the present inventors have been able to evaluate the range of proper charging characteristics of display medium particles by measuring the charge amount of the particles used in the display medium using the same carrier particles in the blow-off method. I found.

Furthermore, in the information display panel of the present invention, it is important to manage the gas in the gap surrounding the 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, and preferably 50% RH or less for the humidity of the gas in the gap.
1A, 1B, 3B, 3B, and 3B, the gaps are defined as electrodes 5 and 6 (electrodes on the inner side of the substrate). 2), the occupied portion of the display medium 3, the occupied portion of the partition wall 4 (when the partition wall is provided), and the gas portion in contact with the so-called display medium, excluding the seal portion of the information display panel.
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 an information display panel so that the humidity is maintained, for example, filling a display medium, assembling an information display panel in a predetermined humidity environment, It is important to apply a sealing material and a sealing method that prevent moisture from entering from the outside.

The distance between the substrates in the information display panel that is the subject of the present invention is not limited as long as the 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 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 display medium is hindered, and if it is less than 5%, the contrast tends to be unclear.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples.

<Example 1>
As shown in Table 1 below, a display medium in which particles made of a predetermined semiconductor material as an external additive are fixed to a surface of a mother particle containing a predetermined charge control agent at a predetermined addition amount (weight ratio with respect to the mother particle). A display in which particles made of a predetermined semiconductor material as an external additive are fixed to a surface of a mother particle containing a black display medium consisting of particles A for use and a predetermined charge control agent at a predetermined addition amount (weight ratio with respect to the mother particles). A white display medium composed of the medium particles B was prepared.

  For each of the prepared display medium particles A and display medium particles B, the particle diameter (d1, d2), particle diameter span, chargeability, and particle diameter ratio of the mother particles and the particles constituting the external additive ( d1 / d2) was determined. The particle diameter and the particle diameter Span were measured according to the above-described example. The chargeability and the charge amount were measured using a suction Faraday cage for particles adhering to the panel substrate after the display was rewritten 100 times on the produced information display panel and the panel was opened. Further, the contact property of the semiconductor material with the substrate was determined according to the following method for confirming rectifying contact.

"Confirming rectifying contact"
Confirmation of rectification can be carried out by examining current-voltage characteristics. First, as shown in FIG. 6, a measurement sample is prepared by laminating a semiconductor film with an Al electrode and an Au electrode provided on one surface and an ITO electrode, an Al electrode, and an Au electrode provided on the other surface. did. The relationship of the work function of the electrode material is Al <ITO <Au. Regarding the preparation of the sample, the electrode was deposited by evaporation, the semiconductor film was deposited by evaporation, or a coating solution dissolved in an arbitrary solvent was formed by spin coating.

  When a voltage is applied between Al and Al, the current-voltage characteristic shows an ohmic contact as shown in FIG. 7, and when a voltage is applied between Al and ITO, the current-voltage characteristic is shown in FIG. As shown in an example, when the rectifying contact is shown and the polarity in which ITO becomes a positive electrode is a forward bias, this semiconductor film can be said to be an electron transporting semiconductor material that makes a rectifying contact with ITO. On the other hand, when a voltage is applied between Au and Au, the current-voltage characteristic shows ohmic contact as shown in FIG. 7, and when a voltage is applied between Au and ITO, the current-voltage characteristic is shown in FIG. As shown in an example, when the rectifying contact is shown and the polarity at which ITO becomes a negative electrode is a forward bias, this semiconductor film can be said to be a hole transporting semiconductor material that makes a rectifying contact with ITO.

  Next, using the prepared black display medium composed of the display medium particles A and the white display medium composed of the display medium particles B, the white display composed of the black display medium composed of the display medium particles A and the display medium particles B. The medium was sealed between two ITO substrates each having an electrode to produce an information display panel. The mixing ratio of the black display medium and the white display medium was set to the same weight, and the filling amount of the display medium between the substrates was adjusted to 30% by volume.

  With respect to the obtained information display panel, the contrast and display quality were obtained as the characteristics of the display panel. The contrast is obtained by measuring the initial display state and the display state after repeating display rewriting 5 million times by alternately applying a voltage of ± 150 V using a reflection image densitometer (RD918, manufactured by Macbeth). It was. As for the display quality, the initial display state and the display state after repeating display rewriting 5 million times by alternately applying a voltage of ± 150 V were visually confirmed. The results are shown in Table 1 below.

<Example 2>
As in Example 1, as shown in Table 2 below, a black display medium composed of display medium particles A and a white display medium composed of display medium particles B were prepared, and an information display panel was prepared using these. Was fabricated and the characteristics were examined. In Example 2, the external additive was pulverized to reduce the particle size. The results are shown in Table 2 below.

<Example 3>
As in Example 1, as shown in Table 3 below, a black display medium composed of display medium particles A and a white display medium composed of display medium particles B were prepared, and an information display panel was prepared using these. Was fabricated and the characteristics were examined. In Example 3, only one of the external additives was a semiconductor material, and the other was a normal external additive. The external additive was pulverized to reduce the particle size of the external additive. The results are shown in Table 3 below.

<Example 4>
As in Example 1, as shown in Table 4 below, a black display medium composed of display medium particles A and a white display medium composed of display medium particles B were prepared, and an information display panel was prepared using them. Was fabricated and the characteristics were examined. In Example 4, as external additives for particles A for display media, OSA1957: 10 g, polycarbonate resin: 10 g were dissolved in 380 g of dichloromethane. The obtained particles were lightly crushed and classified, and the obtained particles were used. The results are shown in Table 4 below.

<Comparative Example 1>
In the same manner as in Example 1, as shown in Table 5 below, a black display medium composed of display medium particles A and a white display medium composed of display medium particles B were prepared, and an information display panel was prepared. The characteristics were investigated. In Comparative Example 1, neither the display medium particle A nor the display medium particle B used an external additive made of a semiconductor material. The results are shown in Table 5 below.

<Comparative example 2>
As in Example 1, as shown in Table 6 below, a black display medium composed of display medium particles A and a white display medium composed of display medium particles B were prepared, and an information display panel was prepared using these. Was fabricated and the characteristics were examined. In Comparative Example 2, both the display medium particle A and the display medium particle B have a large particle diameter in which the ratio d1 / d2 between the particle diameter d2 and the particle diameter d1 of the external additive used exceeds 1/10. The external additive having was used. The results are shown in Table 6 below.

<Comparative Example 3>
In the same manner as in Example 1, as shown in Table 7 below, a black display medium composed of display medium particles A and a white display medium composed of display medium particles B were prepared, and an information display panel was prepared using them. Was fabricated and the characteristics were examined. In Comparative Example 3, both the display medium particle A and the display medium particle B have small particle diameters in which the ratio d1 / d2 between the particle diameter d2 and the particle diameter d1 of the external additive used is less than 1/1000. The external additive having was used. The results are shown in Table 7 below.

  The following can be understood from Examples 1-4 and Comparative Examples 1-3 described above. First, about the effect of including the particle | grains which have the electrical property of a semiconductor on the surface as an external additive, the necessity is understood by comparing Examples 1-4 and the comparative example 1. FIG. Moreover, about the relationship d1 / d2 of the particle diameter d1 of the external additive particle | grains which have the electrical characteristic of a semiconductor on the surface, and the particle diameter d2 of the particle | grains for display media, Example 1-4 is compared with Comparative Examples 2 and 3. Thus, it is understood that 1/1000 ≦ d1 / d2 ≦ 1/10 is preferable.

  The information display panel of the present invention can obtain a reflected image with a wide viewing angle by using a display medium composed of the particles for a display medium of the present invention, and has high visibility like a printed paper, Display units for mobile devices such as notebook PCs, PDAs, mobile phones, handy terminals, electronic papers such as electronic books and electronic newspapers, bulletin boards such as signboards, posters, and blackboards, display units for calculators, home appliances, automobile supplies, etc. Suitable for card displays such as cards and IC cards, electronic advertisements, information boards, electronic POPs (Point Of Presence, Point Of Purchase advertising), electronic price tags, electronic shelf labels, electronic musical scores, and display parts of RF-ID devices Used.

(A), (b) is a figure which shows an example of the information display panel of this invention, respectively. (A), (b) is a figure which shows the other example of the information display panel of this invention, respectively. (A), (b) is a figure which shows the further another example of the information display panel of this invention, respectively. It is a figure for demonstrating the particle for display media (composite particle | grains) in which the external additive particle | grains which comprise a display medium adhered to the surface in the information display panel of this invention. It is a figure which shows an example of the shape of the partition in the information display panel of this invention. It is a figure for demonstrating an example of the confirmation method of the rectifying contact of the semiconductor film in this invention. It is a figure for demonstrating an example of the current-voltage characteristic which shows the ohmic contact in the confirmation method of the rectifying contact shown in FIG. It is a figure for demonstrating an example of the electric current-voltage characteristic which shows the rectifying contact in the confirmation method of the rectifying contact shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Substrate 3 Display medium 3W White display medium 3Wa White display medium particle 3B Black display medium 3Ba Black display medium particle 4 Bulkhead 5, 6 Electrode 11 Particle 12 External additive particle

Claims (5)

  In an information display panel for enclosing at least one kind of display medium between two opposing substrates at least one of which is transparent and applying an electric field to the display medium to move the display medium and display information such as an image, The particles for display medium constituting at least one type of display medium are composite particles in which external additive particles are attached to the surface of the particles. The external additive particles attached to the surface of the particles have electrical characteristics of the semiconductor on the surface. An information display panel comprising particles having the following.   The relationship between the particle diameter d1 of particles having semiconductor electrical characteristics on the surface used for the external additive particles and the particle diameter d2 of the display medium particles is 1/1000 ≦ d1 / d2 ≦ 1/10. The information display panel according to claim 1, wherein the display panel is an information display panel.   The proportion of particles having electrical characteristics of semiconductor on the surface is 0.5% to 5% with respect to the total weight of the external additive particles adhering to the surface of the display medium particles constituting the display medium. The information display panel according to claim 1 or 2.   Of the external additive particles adhering to the surface of the display medium particles constituting the display medium, the semiconductor material on the surface of the particles having semiconductor electrical characteristics on the surface is a hole transporting material or an electron transporting material. The information display panel according to claim 1, wherein: 5. The information display panel according to claim 1, wherein the display medium particles constituting the display medium have at least optical reflectance and charging characteristics.

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