JP2006285008A - Information display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information display panel capable of stably holding surface charges at low cost and stabilizing an information display state of an image etc., for a long period. <P>SOLUTION: The information display panel is constituted by charging at least two or more kinds of display media 3 consisting of at least one or more kinds of particles and differing in optical reflection factor and charging characteristic between two substrates 5 and 6 at least one of which is transparent, and displays information of an image etc., by applying an electric field to the display media and moving the display media. Materials having electric characteristics of a semiconductor are arranged on surfaces of particles for display medium constituting at least one kind of display medium, and particles for display medium which constitute other display media are insulating particles. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention encloses at least two kinds of display media having at least one kind of particles and having different optical reflectance and charging characteristics between two opposing substrates at least one of which is transparent, The present invention relates to an information display panel that displays an information such as an image by applying an electric field to the display medium to move the display medium.

  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 problem, after enclosing a display medium between two opposing substrates, at least one of which is transparent, or forming a cell isolated from each other by a partition, An information display panel that displays information such as an image by applying an electric field to the display medium after the display medium is sealed and moving the display medium 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

  The basis of these display mechanisms is the surface charge of the particles, and in order to obtain a stable high-definition display state, it is necessary to keep the particle surface charges stable. However, the surface charge is very unstable and easily attenuates due to, for example, an environment such as humidity, and easily changes due to contact with or friction with other substances. Also, if some mass transfer or deformation occurs in the particles, the surface charge changes. As is apparent from the display mechanism described above, these changes in surface charge lead to changes in the display state, and there is a problem that the display state becomes unstable due to long-term storage and long-term use of the information display panel. It was.

  An object of the present invention is to solve the above-described problems, and to provide an information display panel that can stably maintain surface charges at low cost and can stabilize an information display state of an image or the like for a long period of time. is there.

  The information display panel according to the present invention comprises at least two kinds of display media having at least one kind of particles between two opposing substrates, at least one of which is transparent, and having different optical reflectivity and charging characteristics. Is an information display panel that displays information such as images by moving the display medium by applying an electric field to the display medium, and the electrical characteristics of the semiconductor on the surface of the particles for the display medium constituting at least one type of display medium In addition, the display medium particles constituting another display medium are made of insulating particles.

  In addition, as a suitable example of the information display panel of the present invention, as a particle for a display medium in which a material having semiconductor electrical characteristics is arranged on a surface constituting at least one type of display medium, a material having semiconductor electrical characteristics is used. Being an electron transporting material, particles having an electron transporting material disposed on the surface thereof are relatively positively charged, a material having semiconductor electrical characteristics is a hole transporting material, hole transporting In some cases, particles having a conductive material disposed on the surface exhibit relatively negative chargeability.

  In addition, as a preferred example of the information display panel of the present invention, as a display medium particle constituting another display medium, a display medium particle in which fine particles subjected to hydrophobic treatment are attached to the surface of an insulating particle is used. Sometimes.

  According to the present invention, a material having electrical characteristics of a semiconductor is disposed on the surface of a display medium particle constituting at least one type of display medium, and the display medium particle constituting another display medium is an insulating particle. Thus, the surface charge of the display medium particles can be stably held, and an information display panel in which an information display state of an image or the like is stable can be obtained. Further, since only one display medium particle is a particle having a particle surface having semiconductor electrical characteristics, the above-described effects can be obtained at low cost.

  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 the 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 the information display panel so that the display medium moves uniformly and can 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 attracted by the Coulomb force between the particles, an electric image force with the electrode and the substrate, an intermolecular force, a liquid cross-linking force, gravity and the like can be considered.

  An example of the information display panel of the present invention will be described based on FIGS. 1 (a), 1 (b), 2 (a) and 2 (b).

  In the example shown in FIGS. 1A and 1B, at least two or more types of display media 3 (here, white display) each having at least one or more types of particles, each having different optical reflectance and charging characteristics. White display medium 3W composed of particles composed of particles for medium and black display medium 3B composed of particles composed of particles for black display medium) to the electric field applied from the outside of the substrates 1 and 2 Accordingly, the black display medium 3B is moved vertically to the substrates 1 and 2 and the black display medium 3B is visually recognized by the observer, or black display is performed, or the white display medium 3W is visually recognized by the observer and white display is performed. Yes. 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) each having at least one or more types of particles, each having different optical reflectance and charging characteristics. A white display medium 3W composed of a particle group composed of particles for the medium and a black display medium 3B composed of a particle group composed of particles for a black display medium) are provided on the electrode 5 and the substrate 2 provided on the substrate 1 Depending on the electric field generated by applying a voltage between the electrodes 6 provided, the substrate 6 is moved perpendicularly to the substrates 1 and 2 so that the black display medium 3B is visually recognized by the observer, or black display is performed. The white display medium 3 </ b> W is visually recognized by the observer to display white. In the example shown in FIG. 2B, in addition to the example shown in FIG. 2A, for example, a partition 4 is provided between the substrates 1 and 2 to form a cell. Further, in FIG. 2 (b), the front partition is omitted.

  A feature of the present invention is that a material having semiconductor electrical characteristics is disposed on the surface of particles for display medium constituting at least one type of display medium, and the particles for display medium constituting another display medium are insulating particles. As a result, the surface charge is stably held at a low cost, and an information display state such as a stable image with high contrast is obtained. Here, as a preferable example of the display medium particle in which a material having semiconductor electrical characteristics is arranged on the surface constituting at least one type of display medium, the material having semiconductor electrical characteristics is an electron transporting material. In addition, particles with an electron transporting material on the surface are relatively positively charged, the material having semiconductor electrical properties is a hole transporting material, and the hole transporting material is on the surface. The present invention can be achieved more effectively by the particles having a relatively negative chargeability.

  In the present invention, as the particles constituting all display media, it is possible to use particles having a surface having a material having semiconductor electrical characteristics, so that the surface charge is stably maintained and information such as an image having a high contrast is stably displayed. On the premise that a state can be obtained, it was considered here that the production of particles with a semiconductor material arranged on the surface is complicated in operation and expensive. In order to achieve this, a material having electrical characteristics of a semiconductor is disposed on the surface of the display medium particles constituting one type of display medium, and the other display medium particles constituting the display medium are insulating particles. By configuring, it is possible to achieve both good display characteristics and low cost.

  Since particles having a semiconductor material arranged on the surface can stably hold electric charge by contact with the substrate, display characteristics can be maintained well even in long-term use. When the particles move, they can come into contact with other particles and apply mechanical stress to the other particles. As a result, the other particles are triboelectrically charged, and the surface charge can be maintained. In addition, collision of particles having a semiconductor material on the surface with other particles held on the substrate weakens the mirror image force with the substrate because the other particles move or rotate, thereby promoting movement. it can. Therefore, good display characteristics can be obtained by enclosing only one type of display medium composed of particles having a semiconductor material arranged on the surface in the panel.

  The method for producing the particles is not particularly limited as long as the above-described electric properties of the electron transport property or the hole transport property can be expressed, but the following method is preferably used as an example. 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.

  In the surface-coated particles, the thickness of the semiconductor material to be surface-covered (or partially arranged on the surface) is not particularly limited, but it is preferably a thin layer in consideration of charge injection efficiency, and is 100 μm or less. Preferably, it is 50 μm or less, more preferably 1 μm or less. When encapsulating in the panel, an appropriate amount of fine particles such as silica or titanium oxide having a particle size considerably smaller than the particles may be imparted for the purpose of improving fluidity.

  Among these, when the surface of the base particles is coated with a semiconductor material, it is preferable to use a surface of the base particles coated with a metal or the like. There is no restriction | limiting in particular as particle material based, A normal general purpose resin, an inorganic material, a metal material, etc. are used suitably. In this case, it is preferable to display the display color as the base particle, and it is necessary to make the color tone particles with good visibility.

  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). Further, nitride semiconductors, sulfide semiconductors, and the like are included, and those doped into these 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.

The layer thickness to be coated on the surface needs to be suppressed to such a level that it does not increase so much that resistance increases and the charge injection efficiency decreases, and it is usually 10 μm or less, preferably 1 μm or less.
The insulating particles to be used are not particularly limited, but particles made of a resin containing a charge control agent and the like are used. Here, the insulation level should be higher than that of the electrode substrate so that charge injection does not easily occur. Usually, the volume resistivity is 1 × 10 ¹⁰ Ωcm or more, preferably 1 × 10 ¹² Ωcm or more. Used. In addition, fine particles formed of metal oxides, inorganic substances, resins, and the like can be added as external additives for the purpose of improving fluidity and ensuring uniformity of charging.

The basic configuration of the display medium particles (also simply referred to as particles) used in the information display panel of the present invention will be described below.
The particles are preferably spherical. 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 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 used in the present invention 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 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 indicating 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 size 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 is 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 particles of the present invention are obtained from a volume-based distribution. Specifically, using a Mastersizer2000 (Malvern Instruments Ltd.) measuring instrument, particles are introduced into a nitrogen stream, and 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 initial charge amount, the contact with the partition wall, the contact with the substrate, the charge associated with the elapsed time. It was found that depending on the attenuation, 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, when a display medium composed of particles for display medium is applied to a dry information display panel, it is important to manage the gas in the void 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, preferably 50% RH or less, more preferably 35% RH or less with respect to the humidity of the gas in the gap.
1A, 1B, 2A, and 2B, the gaps are defined by the electrodes 5 and 6 (electrodes provided from the portion sandwiched between the opposing substrates 1 and 2). ), An occupied portion of the display medium 3, an occupied portion of the partition 4 (when a partition is provided), and a gas portion in contact with a so-called display medium excluding a 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 the information display panel so that the humidity is maintained. For example, filling of the display medium, assembly of the information display panel, etc. are performed in a predetermined humidity environment. It is important to apply a sealing material and a sealing method that prevent moisture from entering.

  There are several possible mechanisms for hydrophobizing the surface of the fine particles. 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). Although the expression mechanism is not particularly limited, it has been found that it is important that the hydrophilic group on the surface of the fine particle and the hydrophobic structure form a chemically strong bond with a reactive treatment agent. This is because if the interaction between the hydrophobic substance and the particle surface is close to or less than the interaction between the particle surface and the hydrophobic substance, or between the substrate and the hydrophobic substance, -It is presumed that the substance is detached from the surface of the fine particles due to the collision between the particles and between the particles and the substrate, and as a result, a strong cohesive force is generated by exposing the hydrophilic surface.

  Examples of the reactive treatment agent used for the hydrophobic treatment of the fine 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-dimethyl) Pentyl) (dichloro / dimethoxy / diethoxy) silane, tri (isopropyl / hexyl / octyl / decyl / methyl /) (chloro / methoxy / ethoxy) silane, (dioctylmethyl / octyldimethyl / (4-isopropylphenyl) diethyl) (chloro / Methoxy / ethoxy) silane, methylhydrogen (poly) siloxane, methylhydrogen (poly) siloxane and dimethyl (poly) siloxa (Random / co) (polymer / oligomer), trimethylsiloxysilicate, 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 is dropped while stirring the fine particles to be treated with a high-speed rotary blade stirrer such as a Henschel mixer. A technique of heating and drying, and a technique of mixing and dispersing the target fine particles in a solution in which the treatment agent is dispersed in a suitable solvent, and then heating and drying the obtained solvent while stirring with a mixer.

In order to determine whether or not the degree of hydrophobicity finally imparted to the surface of the fine particles has reached a level capable of realizing the present invention, the following method can be used. In the present invention, the contact angle CA obtained by this evaluation method satisfies the condition of CA ≧ 90 °, preferably satisfies the condition of CA ≧ 105 °, and more preferably satisfies the condition of CA ≧ 120 °. Is particularly preferably used.
a) A 32G needle for super water repellency is installed in the contact angle meter CA-X manufactured by Kyowa Interface Science Co., Ltd., and distilled water is used as the contact angle measurement liquid.
b) Place the above measuring device in an environment of 25 ° C and 50% RH so that the evaluation stage is horizontal.
c) Prepare a glass preparation, immerse it in the order of a distilled water tank and an ethanol tank, wash it with an ultrasonic cleaner, and dry it thoroughly.
d) The hydrophobized microparticles are arranged so as to be densely packed onto the preparation surface.
e) Using the contact angle meter, measure the contact angle with 4.9 μl (7 scales of the apparatus) of water on the measurement sample surface.

  In addition, the sample in which the fine particles in the above method are densely arranged on the preparation surface can be easily obtained by preparing a dispersion of the fine particles in a suitable solvent, and dropping it on the preparation and drying it. The method is not particularly limited to this method. However, if the density of the fine particle arrangement is insufficient, water droplets leak from the gap and cannot be measured, so care must be taken. In addition, when drying, if agglomerates of fine particles grow too much and the smoothness of the measurement surface is remarkably impaired, measurement variation becomes large and accurate measurement becomes difficult.

  It is presumed that the material of the fine particles is required to have hardness and strength that can withstand collision and shearing with the particles and the substrate. Materials satisfying these conditions 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 crosslinked resin fine particles. For example, silica, titania, and crosslinked resin fine particles are particularly preferably used for this purpose.

  There is a suitable correlation between the insulating particles, which are the display medium particles constituting one display medium, and the particle diameters of the fine particles adhering to the surface. If the particle size of the fine particles is significantly smaller than the particle size of the insulating particles, this means that there are virtually no micro unevenness due to the fine particles formed on the surface of the insulating particles, and between the particles and between the particles and the substrate. The anti-adhesion effect cannot be expected. On the other hand, if the particle diameter of the fine particles becomes excessively large, it becomes necessary to consider the fine particles themselves as one particle, and thus the cohesive force of the fine particles themselves needs to be considered. At this time, the agglomeration force between the fine particles is generally large, and as a result, it is presumed that the agglomeration force works adversely. These particle groups are expected to have a wide distribution of cohesion and adhesion, and when particles are actually allowed to fly in an information display panel, particles that move at a low voltage and particles that move for the first time after applying a high voltage are mixed. As a result, a high voltage is required to make the particles fly uniformly over the entire surface. Alternatively, when driven at a low voltage, the drive failure area appears as a reverse spot. In the present invention, the ratio of the particle diameter D1 of the insulating particles and the average primary particle diameter D2 of the fine particles satisfies the relationship of 0.0001 ≦ D2 / D1 ≦ 0.3, preferably satisfies the relationship of 0.0003 ≦ D2 / D1 ≦ 0.1. More preferably, those satisfying the relationship of 0.0005 ≦ D2 / D1 ≦ 0.05 are particularly preferably used. In addition, particles having an average primary particle diameter D2 of 1 to 1000 nm, preferably 2 to 700 nm, more preferably 3 to 500 nm are particularly preferably used.

  The method for attaching the fine particles to the surface of the insulating particles is not particularly limited, and examples thereof include a method of stirring with a high-speed rotating blade type stirrer such as a Henschel mixer. At this time, the insulating particles and the fine particles may be mixed and stirred after being crushed in advance, or may be continuously pulverized and stirred after mixing both in advance. Further, this treatment may be performed at once or may be performed stepwise by adding the fine particles in several degrees. At this time, it is preferable to appropriately control the temperature and humidity of the processing container so that crushing / dispersing / coating proceeds appropriately.

  Further, in order to adhere the insulating particles and the fine particles more firmly and integrate them, the above-mentioned treatment may be continued and the fine particles may be buried in the surface of the insulating particles to some extent, and between the insulating particles and the fine particles. A third substance that functions as an adhesive layer may be interposed. The method for applying the adhesive layer is not particularly limited. For example, for the insulating particles, a core-shell structure in which a material having an adhesive function on the surface is previously coated thinly, and fine particles are adhered (fixed) to the core-shell structure. The method of doing is mentioned.

The distance between the substrates in the information display panel 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%. When it exceeds 70%, the movement of the display medium is hindered, and when it is less than 5%, the contrast tends to be unclear.

  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 3 can be confirmed from the outside of the 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 uniformity of the distance between the substrates, and if it is thicker than 5000 μm, it will be a thin information display panel. There is an inconvenience.

  Electrode forming materials for providing electrodes on information display panels include metals such as aluminum, silver, nickel, copper, and gold, and conductive metal oxides such as ITO, indium oxide, conductive tin oxide, and conductive zinc oxide. , Conductive polymers such as polyaniline, polypyrrole, polythiophene and the like are exemplified, and are 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 viewing side (display surface 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 display 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 partition 4 provided on the substrate as needed is optimally set according to the type of 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. The height of the partition wall is adjusted to 10 to 500 μm, preferably 10 to 200 μm. As shown in FIG. 3, 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.

  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.

  The information display panels of Examples 1 to 5 and Comparative Example 1 were produced as follows, and various characteristics of the produced information display panels were obtained and compared. First, in each of the following examples, the confirmation method of the rectifying contact used and the measurement method of various measurements of the information display panel will be described, and then each example will be described.

"Confirming rectifying contact"
Confirmation of rectification can be carried out by examining current-voltage characteristics. First, as shown in FIG. 4, a measurement sample is prepared by laminating a semiconductor film with an Al electrode and an Au electrode provided on one side and an ITO electrode, an Al electrode, and an Au electrode provided on the other side. 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 ohmic contact as shown in FIG. 5, and when a voltage is applied between Al and ITO, the current-voltage characteristic is shown in FIG. As 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. 5, 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 in 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.

"Measuring method of various characteristics"
About average particle diameter d (0.5) and particle diameter Span, it measured according to the example mentioned above. After the particles were cut, the coating thickness of the surface layer was measured by observing and measuring Example 1, 2, 3, and 5 using SEM and Example 4 using TEM. The chargeability and the charge amount were measured by using a suction type Faraday cage to open the panel after repeating display rewriting 100 times on the information display panel and to adsorb particles adhering to the panel substrate. Contrast was visually confirmed between the initial display state and the display state after display rewriting was repeated 5 million times by applying a voltage of ± 150V. Regarding the display quality, the initial display state and the display state after the display rewriting was repeated 5 million times by applying a voltage of ± 150 V were visually confirmed.

<Example 1>
According to the following Table 1, the particle | grains 1 which consisted of the particle | grains 1 which coated the resin particle surface with the organic semiconductor, and the insulating particle | grains were prepared. Using the prepared particles 1 and 2, the particles were sealed between two ITO substrates each having an electrode to produce an information display panel. The mixing ratio of the particles 1 and the particles 2 was set to be equal to each other, and the filling amount of the particles between the substrates was adjusted to 30% by volume. The results are shown in Table 1 below.

<Example 2>
According to the following Table 2, the particle | grains 1 which coated the particle | grains 1 which consist of insulating particles, and the resin particle surface with the organic semiconductor were prepared. The prepared particle 1 and particle 2 were used to enclose between two ITO substrates each having an electrode to produce an information display panel. The mixing ratio of the particles 1 and the particles 2 was set to the same weight, and the filling amount of the particles between the substrates was adjusted to 30% by volume. The results are shown in Table 2 below.

<Example 3>
In accordance with Table 3 below, particles 1 composed of insulating particles and particles 1 having a resin surface treated with a metal oxide and then coated with an organic semiconductor were prepared. In addition, the resin particle surface treatment which becomes the particle | grains which become the group | base of the particle | grains for display media is uniformly disperse | distributing the particle | grains which are based on the table | surface shown in Table 3 on a flat plate, and after the surface treatment by laser vapor deposition from the upper part, the resin of the middle process The surface of the particles was uniformly deposited by repeating the process of moving the particles minutely to expose the untreated surface to the surface and similarly performing the surface treatment. Thereafter, the prepared particles 1 and particles 2 were encapsulated between ITO substrates in the same manner as in Example 1 to produce an information display panel. The results are shown in Table 3 below.

<Example 4>
In accordance with Table 4 below, particles 1 made of a metal oxide sputter-treated with a metal oxide and particles 2 made of insulating particles were prepared. The prepared particle 1 and particle 2 were encapsulated between ITO substrates in the same manner as in Example 1 to produce an information display panel. The results are shown in Table 4 below.

<Example 5>
According to Table 5 below, the particle 1 of this example is prepared by keeping the particle 1 described in Example 1 as it is, and the particle 2 of this example is prepared by adding the hydrophobized fine particles to the particle 2 described in Example 1. did. The addition of the hydrophobized microparticles was performed by adding the hydrophobized microparticles shown in Table 5, uniformly dispersing with a Henschel mixer, and attaching the hydrophobized microparticles to the particle surface. The obtained particles 1 and particles 2 were encapsulated between ITO substrates in the same manner as in Example 1 to produce an information display panel. The results are shown in Table 5 below.

<Comparative Example 1>
According to the following Table 6, the semiconductor treatment was eliminated from Example 1, and particles 1 and particles 2 were prepared. The prepared particle 1 and particle 2 were encapsulated between ITO substrates in the same manner as in Example 1 to produce an information display panel. The results are shown in Table 6 below.

  From the above results, Examples 1 to 5 according to the present invention are good in charge amount, contrast, and display quality at the initial stage and after 5 million display rewrites, as compared with Comparative Example 1 outside the scope of the present invention. I know that there is. Further, it has been found that, among the examples, the example 5 can operate with a low driving voltage.

  The information display panel of the present invention includes a display unit of a mobile device such as a notebook computer, a PDA, a mobile phone, and a handy terminal, an electronic paper such as an electronic book and an electronic newspaper, a signboard, a poster, a bulletin board such as a blackboard, a calculator, a household appliance, It is suitably used for display parts for automobile supplies, card display parts such as point cards and IC cards, electronic advertisements, electronic POPs, electronic price tags, electronic shelf labels, electronic musical scores, and display parts for RF-ID devices.

(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. It is a figure which shows an example of the shape of the partition in the information display panel using the particle | grains for display media of this invention as a display medium. 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 current-voltage characteristic which shows the rectifying contact in the confirmation method of the rectifying contact shown in FIG.

Explanation of symbols

1, 2 Substrate 3 Display medium 3W White display medium 3B Black display medium 4 Bulkhead 5, 6 Electrode

Claims (6)

  At least one display medium having at least one kind of particles and having different optical reflectivity and charging characteristics is sealed between two opposing substrates, at least one of which is transparent, and an electric field is enclosed in the display medium. An information display panel that displays information such as an image by moving the display medium by providing a material having a semiconductor electrical property on the surface of particles for display medium constituting at least one type of display medium, An information display panel, wherein particles for a display medium constituting another display medium are insulating particles.   The information display panel according to claim 1, wherein the material having electrical characteristics of a semiconductor is an electron transporting material.   3. The information display panel according to claim 2, wherein the particles having the electron transporting material disposed on the surface thereof are relatively positively charged.   The information display panel according to claim 1, wherein the material having electrical characteristics of a semiconductor is a hole transporting material.   The information display panel according to claim 4, wherein particles having a hole transporting material disposed on a surface thereof exhibit relatively negative chargeability.   6. The display medium particle according to any one of claims 1 to 5, wherein a particle for display medium constituting another display medium is a particle for display medium in which fine particles subjected to hydrophobic treatment are attached to the surface of insulating particles. Information display panel described in the section.

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