JPWO2007080960A1 - Information display panel - Google Patents

Abstract

The present invention uses a combination of white particles for white display medium (3Wa) using an appropriate amount of titanium oxide and black particles for black display medium (3Ba) using an appropriate amount of carbon black. An object of the present invention is to provide an information display panel excellent in display quality, which is composed of a display medium composed of particles for black and white two-color display medium ensuring desired whiteness, blackness and appropriate chargeability. The information display panel of the present application has a structure in which at least one substrate is transparent, and a black and white two-color display medium having different charging polarities is enclosed between two opposing substrates (1) and (2). In the information display panel, a black and white two-color display medium having different charge polarities includes a white display medium (3W) including white particles (3Wa) containing titanium oxide and a charge control agent imparting negative chargeability; And black display medium (3B) containing black particles (3Ba) containing carbon black and a charge control agent imparting positive chargeability. The information display panel of the present application is used for electronic paper.

Description

  In the present invention, a black and white two-color display medium having at least one kind of particles is enclosed between gas cavities between two transparent substrates, at least one of which is transparent, and is generated in the substrate. The present invention relates to an information display panel that displays information by moving a display medium by an applied electric field.

  2. Description of the Related Art In recent years, as an information display panel used for electronic paper applications, two color display media having at least one kind of particles and having different charging polarities are encapsulated between two opposing substrates, at least one of which is transparent. An information display panel that displays information by moving a display medium by an electric field generated in a substrate has been proposed (see, for example, a pamphlet of WO / 2003/050606). In such an electronic paper application, white and black are often selected as a combination of two colors in view of demands such as no fatigue when viewing and excellent visibility (for example, Japanese Patent Application Laid-Open No. 2004-2004). No. 287061).

  When obtaining white particles for a white display medium, titanium oxide is often used as a pigment, and when obtaining black particles for a black display medium, carbon black is often used as a colorant. . However, the particles for the display medium need to have not only whiteness and blackness but also appropriate chargeability in order to be driven by the force of the electric field generated in the substrate. Appropriate chargeability means that white particles for white display medium and black particles for black display medium have opposite charging polarities, and the amount of charge can be easily driven by the force of an electric field. Means.

  However, titanium oxide has the property of making the particles containing it negatively charged, while carbon black is electrically conductive, so that it is sufficient for a display medium composed of black and white two-color display medium particles. A display medium having whiteness, sufficient blackness and appropriate chargeability could not be obtained.

  The present invention uses a combination of white particles for a white display medium using an appropriate amount of titanium oxide and black particles for a black display medium using an appropriate amount of carbon black. It is an object of the present invention to provide an information display panel excellent in display quality, which is composed of a display medium composed of particles for black and white two-color display medium, which secures the property and proper chargeability.

  The first invention of the information display panel according to the present invention is information having a structure in which at least one substrate is transparent and a black and white two-color display medium having different charging polarities is enclosed between two opposing air gaps between the substrates. In a display panel, a black and white two-color display medium having different charge polarities, a white display medium containing at least white particles containing at least titanium oxide and a charge control agent imparting negative chargeability, at least carbon black and a plus And a black display medium including at least black particles containing a charge control agent imparting charging properties.

  A second invention of the information display panel of the present invention is an information having a structure in which at least one substrate is transparent and a black and white two-color display medium having different charging polarities is enclosed between two opposing air gaps between the substrates. A display panel that is provided with a partition wall that continuously or intermittently provides a partition wall that holds a gap between the two substrates and partitions the space between the substrates. In an information display panel having a structure in which a monochrome display medium is enclosed in a space cell, a unit pixel is constituted by three cells, and at least three substrates having transparent primary colors on the substrate side which is the display surface side. A white display medium comprising at least a white particle containing at least titanium oxide and a charge control agent imparting negative chargeability, and a black and white two-color display medium having different charge polarities and a color filter disposed therein When, it is characterized in that consisted of at least including black color display media black particles containing a charge control agent which imparts at least carbon black and the positive charging property.

  As a preferred example of the information display panel of the present invention, the titanium oxide contained in the white particles constituting the white display medium having a negative charge polarity is 10 parts by weight or more, and a black display medium having a positive charge polarity is used. The carbon black contained in the constituting black particles may be 0.1 to 10 parts by weight.

  According to the information display panel of the present invention, a white color constituting a white display medium having a sufficient white color and an appropriate negative charge polarity obtained by setting the titanium oxide content to preferably 10 parts by weight or more. Particles, and black particles constituting a black display medium having a sufficient black and appropriate positive charge polarity, obtained by setting the carbon black content preferably in the range of 0.1 to 10 parts by weight, Since the display medium of two colors having different charging polarities is constituted, the information display panel having excellent display quality, comprising the display medium of black and white two colors ensuring the desired whiteness, blackness and appropriate chargeability It becomes.

(A), (b) is a figure which shows an example of the information display panel of this invention. (A), (b) is a figure which shows the other example of the information display panel of this invention. It is a figure which shows the further another example of the information display panel of this invention. It is a figure which shows the further another example of 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 which shows the measuring point of the surface potential of the colored particle which comprises the particle | grains for display media used for the information display panel of this invention.

  First, the basic configuration of the information display panel of the present invention will be described. In the information display panel which is an object 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 display medium changes the moving direction by the electric field direction change due to the potential switching, thereby displaying information such as an image. Made. Therefore, it is necessary to design the information display panel so that the display medium can move uniformly and maintain stability when rewriting the display repeatedly or when displaying the display information continuously. 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. 2 (a) and 2 (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. A conductive member can also be provided in layers on the inner side (side in contact with the display medium) of each of the two substrates. As the conductive member, a conductive metal oxide such as tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), indium oxide, or tin-doped antimony oxide (ATO) is preferably used.

  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. The electrodes opposed to each other can be individual electrodes or line electrodes orthogonal to each other. The electrodes are preferably provided inside each of the two substrates (on the side in contact with the display medium). As electrode materials, tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), indium oxide and tin-doped oxide are used. A conductive metal oxide such as antimony (ATO) is preferably used.

  The above description is similarly applied to the case where the white display medium 3W including the particle group is replaced with the white display medium including the powder fluid and the black display medium 3B including the particle group is replaced with the black display medium including the powder fluid. I can do it. The powder fluid will be described later.

  The present invention is characterized in that, in the information display panel having the above-described configuration, at least white particles containing at least titanium oxide and a charge control agent imparting negative chargeability are displayed at least in a black and white display medium having different charging polarities. And a black display medium including at least black particles containing at least carbon black and a charge control agent imparting positive chargeability.

  Here, the white particles constituting the white display medium contain 10 parts by weight or more, preferably 20 parts by weight or more of titanium oxide, and the black particles constituting the black display medium contain 0.1% of carbon black. It is preferable to comprise so that it may contain in 10-10 weight part.

  In addition, it is desirable that the amount of titanium oxide contained in the white particles constituting the white display medium is as large as possible. However, when white particles are obtained by a polymerization method, it is difficult to produce a content exceeding 100 parts by weight. It is produced in the range of 10 to 100 parts by weight.

  When the white particles constituting the white display medium are obtained by the kneading / pulverization / classification method, a large amount of titanium oxide can be contained unlike the polymerization method, so when obtaining the white particles, the amount exceeds 100 parts by weight. Also, it can be produced in a range of 10 to 500 parts by weight, preferably 50 to 300 parts by weight, and more preferably 100 to 200 parts by weight. Here, even when white particles constituting the white display medium are obtained by a kneading / pulverization / classification method, a sufficient white color cannot be obtained if the titanium oxide is less than 10 parts by weight. Moreover, when it exceeds 500 weight part, there exists a problem which particle strength falls and it becomes easy to break, and a problem which becomes difficult to knead | mix.

  If the amount of carbon black contained in the black particles constituting the black display medium is 0.1 parts by weight or more, a sufficient black color is obtained, but if it is less than 0.1 parts by weight, a sufficient black color cannot be obtained. Further, when the amount exceeds 10 parts by weight, the conductivity becomes large and proper positive chargeability cannot be obtained and the particles do not function as display medium particles. Therefore, the black particles are produced with a carbon content in the range of 0.1 to 10 parts by weight. Is done.

  3 to 4 are diagrams for explaining other examples of the information display panel of the present invention. In the example shown in FIGS. 3 to 4, the same members as those shown in FIGS. 1A and 1B and FIGS. 2A and 2B are denoted by the same reference numerals, and the description thereof is omitted. . The example shown in FIGS. 3 to 4 shows an example in which color display is possible. In the transparent substrate 2 on the display surface side, the three primary colors correspond to the cells 11 consisting of the gas space divided by the partition walls 4. Color filters 12R (red), 12G (green), and 12B (blue purple) are provided separately, and one pixel is composed of three cells 11 each provided with color filters 12R, 12G, and 12B. It is possible. 3 to 4, the example illustrated in FIG. 3 illustrates an example in which the color filters 12 </ b> R, 12 </ b> G, and 12 </ b> B are provided on the outer surface of the transparent substrate 2. In the example shown in FIG. 4, the color filters 12R, 12G, and 12B are provided in contact with the different electrodes 6. In any example, the color display in the present invention can be suitably performed.

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

  Regarding the substrate, at least one of the substrates is a transparent substrate 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 other substrate 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 a material for forming electrodes and conductive members 5 and 6 when electrodes and conductive members are provided on the substrate of the information display panel, metals such as aluminum, silver, nickel, copper and gold, tin-doped indium oxide (ITO), Examples include conductive metal oxides such as zinc-doped indium oxide (IZO), tin-doped antimony oxide (ATO), indium oxide, conductive tin oxide, and conductive zinc oxide, and conductive polymers such as polyaniline, polypyrrole, and polythiophene. These are selected and used as appropriate. As a method for forming the electrode and the conductive member, the above-described materials are formed into a thin film by sputtering, vacuum vapor deposition, CVD (chemical vapor deposition), coating method, etc., or the conductive agent is used as a solvent or a synthetic resin binder. A method of mixing and applying is used. In many cases, the electrodes and conductive members provided on the display surface side substrate need to be transparent, but the electrodes and conductive members provided on the back surface side substrate do not need to be transparent. In any case, the above-mentioned material which can be patterned and is conductive can be preferably used. The thickness of the electrode and the conductive member 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 and conductive member provided on the back side substrate 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 electrode and the conductive member are preferably provided on the inner side (side in contact with the display medium) of the substrate.

  The partition 4 provided on the substrate as required is optimally set depending on the type of display medium involved in display, and is not limited in general. However, 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. In forming the partition walls, a both-rib method in which ribs are formed on each of the opposing substrates and then bonded, and a one-rib method in which ribs are formed only on one substrate are conceivable. In the present invention, any method is preferably used.

  As shown in FIG. 5, the cells formed by the partition walls made of these ribs are exemplified by a square shape, a triangular shape, a line shape, a circular shape, and a hexagonal shape as viewed from the plane of the substrate. And a mesh shape. It is better to make the portion corresponding to the partition wall cross-sectional portion visible from the display side (the area of the cell frame) as small as possible, and the clearness of the display state increases. Here, 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. Among these, a photolithography method using a resist film and a mold transfer method are preferably used.

  Next, the powder fluid used as a display medium in the information display panel of the present invention will be described. As for the name of the powder fluid as the display medium of the present invention, the present applicant has obtained the right of “Electronic Powder Fluid (registered trademark): Registration No. 4636931”.

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

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

The information display panel of the present invention encloses a powder fluid that exhibits high fluidity in an aerosol state in which solid particles are stably suspended as a dispersoid, for example, as a display medium, between opposing substrates, at least one of which is transparent. Such a powder fluid is so fluid that the angle of repose, which is an index indicating the fluidity of the powder, cannot be measured, and is easily stabilized by the Coulomb force with a small electric field force. Can be moved.
As described above, for example, the powder fluid used as the display medium in the present invention is a substance in the intermediate state between the fluid and particles that exhibits fluidity by itself without borrowing the force of gas or liquid. It is. This powder fluid can be in an aerosol state in particular, and in the information display panel of the present invention, a solid substance is used in a state of relatively stably floating as a dispersoid in the gas.

Next, display medium particles (hereinafter also referred to as particles) constituting the display medium in the information display panel of the present invention will be described. The colored particles for display medium may be composed of colored particles as they are to form a display medium, or may be combined with other particles to form a display medium, or may be adjusted and configured to become a powder fluid to form a display medium. Used.
The display medium particles of the present invention may be white particles having a negative charge polarity and black particles having a positive charge polarity. In particular, the display medium is preferably configured as particles having a spherical shape and a small specific gravity.

  A method for charging the display medium particles positively or negatively is not particularly limited, and a charging method such as a corona discharge method, an electrode injection method, or a friction method is used. In the charge amount of black and white display medium particles used in the information display panel of the present invention, the charge amount measured by the blow-off method using the same carrier is 5 to 150 μC / g in absolute value. The difference is preferably 5 to 150 μC / g in absolute value. When the absolute value of the charge amount and the absolute value of the charge amount difference are smaller than this range, the response speed with respect to the change in the electric field is slowed, and the memory property is also lowered. If the absolute value of the charge amount and the absolute value of the charge amount difference are larger than this range, the image force on the electrode and the substrate is too strong, and the memory property is good, but the reversibility of the display medium when the electric field direction is reversed is good. Deteriorate.

  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. The charge amount was measured as follows.

<Blow-off measurement principle and measurement method>
In the blow-off method, a mixture of display medium particles and carrier particles is placed in a cylindrical container with nets at both ends, and high-pressure gas is blown from one end to separate the display medium particles and carrier particles. From the opening, only the particles for display medium are blown off. At this time, the charge amount equivalent to the charge amount of the display medium particles taken away from the container remains in the carrier particles. All of the electric flux due to this charge is collected by the Faraday cage, and the capacitor is charged by this amount. Therefore, by measuring the potential across the capacitor, the charge amount Q of the display medium particles is
Q = CV (C: capacitor capacity, V: voltage across the capacitor)
As required.

  TB-200 manufactured by Toshiba Chemical Corporation was used as the blow-off charge measuring device. In the present invention, the ferrite carrier particles are used for measuring the charge amount of the particles for the display medium to be measured. However, the information display panel includes a display medium composed of positively charged particles and a display medium composed of negatively charged particles. When the two types of display media are used in combination, the carrier particles of the same type are used when measuring the charge amount of the display medium particles constituting each display medium. Specifically, the charge amount (μC / g) of the particles was measured using DFC100 wrinkle (Mn—Mg-containing ferrite system) manufactured by Dowa Iron Powder Industry Co., Ltd. as carrier particles.

Since the particles for display medium need to retain the charged charge, insulating particles having a volume resistivity of 1 × 10 ¹⁰ Ω · cm or more are preferable, and in particular, the volume resistivity is 1 × 10 ¹² Ω · cm or more. Insulating particles are preferred. Further, particles with slow charge decay evaluated by the method described below are more preferable.

  That is, particles for a display medium to be measured are arranged on the surface of a roll-shaped measuring jig, and a voltage of 8 KV is applied to a corona discharger arranged at a distance of 1 mm from the arranged particles for display medium. Electric discharge is generated to charge the surface of the display medium particle, and the change in the surface potential is measured and judged. In this case, it is important to select and produce the display medium particle constituent material so that the maximum value of the surface potential after 0.3 seconds is greater than 300V, and preferably greater than 400V.

  In addition, the measurement of the said surface potential can be performed, for example with the apparatus (CRT2000 by QEA) shown in FIG. In the case of this apparatus, both ends of the shaft of the roll-shaped measuring jig having the display medium particles to be measured arranged on the surface are held by the chuck 21, and a small scorotron discharger 22 and a surface potential meter 23 are used. Are arranged with a predetermined interval between them and the particle surface for the display medium to be measured with a spacing of 1 mm, and the measurement unit is used for roll measurement while the roll measurement jig is stationary. A method of measuring the surface potential of the display medium particles disposed on the surface of the jig by moving the display medium particles from one end to the other end at a constant speed while applying a surface charge is suitably employed. The measurement environment is a temperature of 25 ± 3 ° C. and a humidity of 55 ± 5 RH%.

  The display medium particles may be made of any material as long as whiteness, blackness, charging performance, and the like are satisfied. For example, it can be formed from a resin, a charge control agent, a colorant, an inorganic additive, and the like. As the particles for the display medium, it is preferable to use particles having a glass transition temperature Tg of 60 ° C. or higher of the resin constituting the particles. The particles for white display media contain other charge control agents, other colorants, inorganic additives, etc., in addition to titanium oxide and charge control agents that impart negative chargeability to the main resin. be able to. The particles for black display media contain carbon black, a charge control agent that imparts positive chargeability, and other charge control agents, other colorants, inorganic additives, etc., as the main resin. be able to. 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.

  Further, styrene derivatives such as styrene, α-methylstyrene, p-chlorostyrene, chloromethylstyrene; vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; unsaturated nitriles such as acrylonitrile; (meth) acrylic acid Methyl, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, ethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl Examples thereof include resins obtained by polymerizing polymerizable monomers such as (meth) acrylate derivatives such as (meth) acrylate and cyclohexyl (meth) acrylate. These polymerizable monomers may be used alone or in combination of two or more.

  Moreover, when synthesizing the resin, for example, a crosslinkable monomer may be added in order to improve the properties of the display medium particles. Examples of crosslinkable monomers include divinylbenzene, divinylbiphenyl, divinylnaphthalene, polyethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (Meth) acrylate, tetramethylol methane tri (meth) acrylate, tetramethylolpropane tetra (meth) acrylate, diallyl phthalate and its isomers, divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, diallyl phthalate, etc. Crosslinkable monomers such as triallyl isocyanurate and derivatives thereof having two or more unsaturated bonds may be added. These crosslinkable monomers may be used independently and may use 2 or more types together.

  Especially, it is preferable to consist of highly crosslinked resin formed by superposing | polymerizing the monomer mixture containing the said crosslinkable monomer. When such a highly crosslinkable resin is used, sufficient mechanical performance can be maintained even if a large amount of titanium oxide is contained as described above.

  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), nitroimidazole derivatives, and the like, which do not affect the whiteness of the white display medium particles. 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.

  Carbon black is used as the black colorant. Further, titanium oxide is used as the white colorant.

  In addition, the particles for display medium of the present invention have an average particle diameter d (0.5) in the range of 1 to 20 μm, and are preferably uniform and uniform. If the average particle diameter d (0.5) is larger than this range, the display is not clear. If the average particle diameter d (0.5) is smaller than this range, the cohesive force between the particles becomes too large, which hinders movement as a display medium.

Furthermore, in the present invention, regarding the particle size distribution of the particles for each display medium, 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 for display medium, the ratio of d (0.5) of the particles having the minimum diameter to d (0.5) of the particles having the maximum diameter among the particles for display medium used is preferably 50 or less, preferably It is important to set it to 10 or less. Even if the particle size distribution Span is reduced, particles for display media with different charging properties move in opposite directions, so that the particle sizes are close to each other, and each particle can be easily moved in the opposite direction by the equivalent amount. This is preferred and this is the range.

The particle size distribution and the particle size can be obtained from a laser diffraction / scattering method or the like. When the display medium particles to be measured are irradiated with laser light, a spatial light intensity distribution pattern of diffracted / scattered light is generated, and this light intensity pattern has a corresponding relationship with the particle diameter. 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, the particles are put 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 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.

Furthermore, in the dry information display panel that drives the display medium in the gas space as in 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, 2A, and 2B, the gaps are defined as electrodes 5 and 6 (electrodes on the inner side of the substrate). Gas) in contact with a so-called display medium excluding the occupied portion of the display medium (particle group or powdered fluid) 3, the occupied portion of the partition wall 4 (when the partition wall is provided), and the seal portion of the information display panel. It shall refer to the part.
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, etc. 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 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 gas 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.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples of the present invention, but the present invention is not limited to the following examples.

<Production Example 1 of White Particles for White Display Medium (Styrene: Polymerization Method)>
As white particles for a negatively charged white display medium, 10 parts by weight of titanium oxide (Taipek CR-50: manufactured by Ishihara Sangyo), 95 mol% of styrene monomer (Kanto Chemical Reagent) and 5 mol% of methacrylic acid (Kanto Chemical Reagent) As a negatively chargeable charge control agent, a surfactant is prepared by dissolving 5 parts by weight of a phenol-based condensate (Bontron E89: manufactured by Orient Chemical) and further 2 parts by weight of lauryl peroxide (Perroyl L: manufactured by Nippon Oil & Fats). After being suspended in purified water to which 0.5% latemul E-118B (manufactured by Kao) was added, polymerized, filtered and dried, the average particle size was determined using a classifier (MDS-2: Nippon Pneumatic Industry). 9.3 μm white particles were obtained. The charge amount of the obtained particles was −40 μC / g, and the maximum value of the surface potential after 430 seconds after the surface potential measurement was 430V. The Tg (glass transition temperature) of the resin component of the particles was 98 ° C. A white display medium was constituted by the group of white particles. In addition, Tg (glass transition temperature) of styrene resin is 92 degreeC, and Tg (glass transition temperature) of methacrylic acid resin is 130 degreeC. When the whiteness of the obtained particles was measured with an image densitometer (RD918: manufactured by Gretag Macbeth Co., Ltd.), the optical density was 0.08, which was sufficient as whiteness.

<Production Example 2 of White Particles for White Display Medium (Styrene / Divinylbenzene System: Polymerization Method)>
As white particles for negatively charged white display media, 30 parts by weight of titanium oxide, 50 mol% of styrene monomer (Kanto Chemical Reagent) and 50 mol% of divinylbenzene (Kanto Chemical Reagent), phenol-based condensation as a negatively charged charge control agent A product obtained by dissolving 5 parts by weight of a product (Bontron E89: manufactured by Orient Chemical Co., Ltd.) and 2 parts by weight of lauryl peroxide (Perroyl L: manufactured by Nippon Oil & Fats) was used as a surfactant with Latemulu E-118B (manufactured by Kao) as 0. After suspended in 0.5% purified water, polymerized, filtered, and dried, white particles having an average particle size of 9.0 μm were obtained using a classifier (MDS-2: Nippon Pneumatic Industry). The charge amount of the obtained particles was −90 μC / g, and the maximum value of the surface potential after 430 seconds after the surface potential measurement was 430V. A white display medium was constituted by the group of white particles. The whiteness of the obtained particles was measured with an image densitometer (RD918: manufactured by Gretag Macbeth Co., Ltd.). As a result, the optical density was 0.07, which was sufficient as whiteness.

<Production Example 3 of White Particles for White Display Medium (Cycloolefin: Kneading / Crushing / Classification Method)>
100 parts by weight of cycloolefin resin (manufactured by Nippon Zeon Co., Ltd., trade name: ZEONOR), 100 parts by weight of titanium oxide (trade name: CR90, manufactured by Ishihara Sangyo), phenol-based condensate (Bontron E89: (Orient Chemical) 5 parts by weight is mixed with a Henschel-type mixer (FM50 / 1, Mitsui Mining Co., Ltd.), and the resulting mixture is kneaded / manufactured with a twin screw extruder (KZW15-45MG (Technobel Co., Ltd.)). The particles were pelletized and further pulverized / classified using a jet mill (labor jet mill, Nippon Pneumatic Co., Ltd.) to obtain white particles having an average particle size of 9.0 μm. The charge amount of the obtained particles was −110 μC / g, and the maximum value of the surface potential after 420 seconds of the surface potential measurement was 420V. A white display medium was constituted by the group of white particles. When the whiteness of the obtained particles was measured with an image densitometer (RD918: manufactured by Gretag Macbeth Co., Ltd.), the optical density was 0.07, which was sufficient as whiteness.

<Production Example 4 of White Particles for White Display Medium (Methylpentene: Kneading / Crushing / Classification Method)>
100 parts by weight of a methylpentene resin (trade name: TPX, manufactured by Mitsui Chemicals), 220 parts by weight of titanium oxide (trade name: CR60-2, manufactured by Ishihara Sangyo), a phenol-based condensate (Bontron) as a negatively charged charge control agent E89: Orient Chemical Co., Ltd. (5 parts by weight) was mixed with a Henschel mixer (FM50 / 1, Mitsui Mining Co., Ltd.), and the resulting mixture was kneaded with a twin-screw extruder (KZW15-45MG, Technobel Co., Ltd.). / Granulated and pelletized, and further pulverized / classified using a jet mill (Lab Jet Mill, Nippon Pneumatic Co., Ltd.) to obtain white particles having an average particle size of 8.7 μm. The charge amount of the obtained particles was −93 μC / g, and the maximum value of the surface potential after 440 seconds of the surface potential measurement was 440V. A white display medium was constituted by the group of white particles. The whiteness of the obtained particles was measured with an image densitometer (RD918: manufactured by Gretag Macbeth Co., Ltd.). As a result, the optical density was 0.07, which was sufficient as whiteness.

<Production Example 5 of White Particles for White Display Medium (Styrene: Polymerization Method)>
As white particles for a negatively charged white display medium, titanium oxide 5 parts by weight (Taipeku CR-50: manufactured by Ishihara Sangyo), styrene monomer (Kanto Chemical Reagent) 95 mol% and methacrylic acid (Kanto Chemical Reagent) 5 mol%, As a negatively chargeable charge control agent, a surfactant is prepared by dissolving 5 parts by weight of a phenol-based condensate (Bontron E89: manufactured by Orient Chemical) and further 2 parts by weight of lauryl peroxide (Perroyl L: manufactured by Nippon Oil & Fats). After being suspended in purified water to which 0.5% latemul E-118B (manufactured by Kao) was added, polymerized, filtered and dried, the average particle size was determined using a classifier (MDS-2: Nippon Pneumatic Industry). 9.5 μm white particles were obtained. The charge amount of the obtained particles was −37 μC / g, and the maximum value of the surface potential after 420 seconds of the surface potential measurement was 420V. The Tg (glass transition temperature) of the resin component of the particles was 98 ° C. When the whiteness of the white particles was measured with an image densitometer (RD918: manufactured by Gretag Macbeth), the result was that the optical density was 0.1, which was insufficient as whiteness.

<Production Example 6 of White Particles for White Display Medium (Methylpentene: Kneading / Crushing / Classification Method)>
100 parts by weight of methylpentene resin (trade name: TPX, manufactured by Mitsui Chemicals), 600 parts by weight of titanium oxide (trade name: CR60-2, manufactured by Ishihara Sangyo Co., Ltd.), a phenol-based condensate (Bontron) as a negatively charged charge control agent E89: Orient Chemical Co., Ltd. (5 parts by weight) was mixed with a Henschel mixer (FM50 / 1, Mitsui Mining Co., Ltd.), and the resulting mixture was kneaded with a twin-screw extruder (KZW15-45MG, Technobel Co., Ltd.). / Pelletization was attempted by granulation, but extrusion was not possible and desired white particles could not be obtained.

<Example 7 of production of white particles for white display medium (methylpentene: kneading / pulverization / classification method)>
100 parts by weight of methylpentene resin (trade name: TPX, manufactured by Mitsui Chemicals), 400 parts by weight of titanium oxide (trade name: CR60-2, manufactured by Ishihara Sangyo Co., Ltd.), a phenol-based condensate (Bontron) as a negatively charged charge control agent E89: Orient Chemical Co., Ltd. (5 parts by weight) was mixed with a Henschel mixer (FM50 / 1, Mitsui Mining Co., Ltd.), and the resulting mixture was kneaded with a twin-screw extruder (KZW15-45MG, Technobel Co., Ltd.). / Granulated and pelletized, and further pulverized / classified using a jet mill (Lab Jet Mill, Nippon Pneumatic Co., Ltd.) to obtain white particles having an average particle size of 8.7 μm. The whiteness of the obtained particles was measured with an image densitometer (RD918: manufactured by Gretag Macbeth Co., Ltd.). As a result, the optical density was 0.07, which was sufficient as whiteness.

<Example 1 of production of black particles for black display medium (acrylic)>
As black particles for positively charged black display media, 98 parts by weight of methyl methacrylate monomer (Kanto Chemical Reagent) and acryloylmorpholine (ACMO: manufactured by Kojin) and nigrosine compound (Bontron NO7: Orient) as a positively charged charge control agent 3 parts by weight of chemical) and 10 parts by weight of carbon black (special black 5: manufactured by Tegussa) as a black pigment are dispersed by a sand mill, and further 2 parts by weight of lauryl peroxide (Perroyl L: manufactured by NOF Corporation) are dissolved. The solution was suspended and polymerized in purified water to which 0.5% of sodium polyoxyethylene alkyl ether sulfate (Latemul E-118B: manufactured by Kao) was added as a surfactant, polymerized, filtered and dried. MDS-2: Nippon Pneumatic Industry) with an average particle size of 8.8 μm To obtain the color particles. The charge amount of the obtained particles was +47 μC / g, and the maximum value of the surface potential after 450 seconds of the surface potential measurement was 450V. The Tg (glass transition temperature) of the resin component of the particles was 110 ° C. A black display medium was constituted by the particle group of the black particles. The Tg (glass transition temperature) of the methyl methacrylate resin is 105 ° C., and the Tg (glass transition temperature) of the acryloylmorpholine resin is 145 ° C. When the blackness of the black particles was measured with an image densitometer (RD918: manufactured by Gretag Macbeth), the optical density was 1.3, which was sufficient as blackness.

<Example 2 of production of black particles for black display medium (acrylic)>
As black particles for a positively charged black display medium, 98 parts by weight of methyl methacrylate monomer (Kanto Chemical Reagent) and acryloylmorpholine (ACMO: manufactured by Kojin) and a nigrosine compound (Bontron NO7: Orient) as a positively charged charge control agent 3 parts by weight of chemical) and 15 parts by weight of carbon black (special black 5: manufactured by Tegussa) as a black pigment are dispersed by a sand mill, and further 2 parts by weight of lauryl peroxide (Perroyl L: manufactured by NOF Corporation) are dissolved. The liquid was suspended in purified water to which 0.5% of sodium polyoxyethylene alkyl ether sulfate (Latemul E-118B: manufactured by Kao) was added as a surfactant, polymerized, filtered, dried, and then classified by a classifier ( MDS-2: Nippon Pneumatic Industry) with an average particle size of 8.5 μm To obtain the color particles. The charge amount of the obtained particles could not be measured. Also, the surface potential after 0.3 seconds of the surface potential measurement could not be measured. The Tg (glass transition temperature) of the resin component of the particles was 110 ° C. A black display medium was constituted by the particle group of the black particles. The Tg (glass transition temperature) of the methyl methacrylate resin is 105 ° C., and the Tg (glass transition temperature) of the acryloylmorpholine resin is 145 ° C. When the blackness of the black particles was measured with an image densitometer (RD918: manufactured by Gretag Macbeth), the optical density was 1.3, which was sufficient as blackness.

<Example 3 of production of black particles for black display medium (acrylic)>
As black particles for positively charged black display media, 98 parts by weight of methyl methacrylate monomer (Kanto Chemical Reagent) and acryloylmorpholine (ACMO: manufactured by Kojin) and nigrosine compound (Bontron NO7: Orient) as a positively charged charge control agent Chemical) 3 parts by weight and carbon black as a black pigment (Special Black 5: manufactured by Tegusa) 0.05 parts by weight are dispersed by a sand mill, and further 2 parts by weight of lauryl peroxide (Perroyl L: manufactured by NOF Corporation) The dissolved liquid is suspended in purified water to which 0.5% of sodium polyoxyethylene alkyl ether sulfate (Latemul E-118B: manufactured by Kao) is added as a surfactant, polymerized, filtered, dried, and classified. Machine (MDS-2: Nippon Pneumatic Industry) To obtain the black particles. The charge amount of the obtained particles was +40 μC / g, and the maximum value of the surface potential after 470 seconds after the surface potential measurement was 470V. The Tg (glass transition temperature) of the resin component of the particles was 110 ° C. When the blackness of the black particles was measured with an image densitometer (RD918: manufactured by Gretag Macbeth Co., Ltd.), the optical density was 1.2, and the blackness was insufficient.

  The display medium was charged by friction charging by mixing and stirring both display media in equivalent amounts.

"Production of information display panel"
A dry film photoresist NIT250 made by Nichigo Morton, which is a photosensitive film, is laminated on a glass transparent substrate (20 cm □) provided with a line electrode (width: 300 μm, line pitch: 340 μm) on which an ITO electrode portion is arranged. Then, by partitioning with exposure and development, a partition (width: 20 μm, height: 50 μm) having a shape and arrangement corresponding to the pixel size was formed to prepare a cell (square, grid-like arrangement) filled with a display medium. .
On the other substrate, a transparent glass substrate provided with a copper comb line electrode (width: 300 μm, line pitch: 340 μm) was prepared.

  Next, a white display medium and a black display medium having different charging characteristics were first filled with a white display medium in a cell on a display side substrate provided with a partition wall, and then filled with a black display medium. The filling arrangement amount of both display media was set to the same volume amount, and the volume occupation ratio of both display media with respect to the space between the substrates formed by bonding the two substrates was adjusted to 25 vol%.

  Next, the other substrate is overlaid on the substrate filled with the display medium in the cell so that the line-shaped electrodes are orthogonal to each other, and the outer periphery of the substrate is bonded and sealed with an epoxy adhesive. An information display panel was prepared by enclosing the display medium.

"Evaluation of information display panel"
10 pieces of information display panels described in Examples 1 and 2 and Comparative Example 1 were produced and incorporated in the information display device, and a voltage was applied to the electrodes so as to display a solid image and a staggered lattice image. Then, the quality of the displayed image was visually observed and evaluated.

<Example 1>
Information is displayed by combining the white display medium composed of the white particles produced in Production Example 1 of white particles for white display medium and the black display medium comprised of the black particles produced in Production Example 1 of black particles for black display medium. Panels were prepared and evaluated according to the above. The results are shown in Table 1.

<Example 2>
Information display by combining the white display medium composed of the white particles produced in Production Example 2 of white particles for white display medium and the black display medium comprised of the black particles produced in Production Example 1 of black particles for black display medium Panels were prepared and evaluated according to the above. The results are shown in Table 1.

<Example 3>
Information display by combining the white display medium composed of the white particles produced in Production Example 3 of white particles for white display medium and the black display medium comprised of the black particles produced in Production Example 1 of black particles for black display medium Panels were prepared and evaluated according to the above. The results are shown in Table 1.

<Example 4>
Information display by combining the white display medium composed of the white particles prepared in Production Example 4 of white particles for white display medium and the black display medium composed of the black particles produced in Production Example 1 of black particles for black display medium Panels were prepared and evaluated according to the above. The results are shown in Table 1.

<Comparative Example 1>
Information display by combining the white display medium composed of the white particles produced in Production Example 1 of white particles for white display medium and the black display medium comprised of the black particles produced in Production Example 2 of black particles for black display medium Panels were prepared and evaluated according to the above. The results are shown in Table 1.

<Comparative example 2>
Information display by combining the white display medium composed of the white particles produced in Production Example 3 of white particles for white display medium and the black display medium comprised of the black particles produced in Production Example 2 of black particles for black display medium Panels were prepared and evaluated according to the above. The results are shown in Table 1.

  An information display panel and an information display apparatus using the same according to the present invention include display units of mobile devices such as notebook computers, PDAs, mobile phones, handy terminals, electronic books, electronic newspapers, electronic manuals (instruction manuals), etc. Electronic paper, signboards, posters, bulletin boards such as blackboards, calculators, home appliances, display parts for automobiles, point displays, card displays such as IC cards, electronic advertisements, information boards, electronic POPs (Point Of Presence, Point Of Purchase advertising), electronic shelf label, electronic price tag, electronic score, display part of RF-ID equipment, etc., external electric field drive type display panel (so-called rewritable paper) that rewrites display by electric field drive by external electric field forming means, etc. Is preferably used.

Claims (4)

  In an information display panel having a structure in which a display medium of two colors of black and white having different charging polarities is enclosed between two opposing gas cavities in which at least one substrate is transparent, black and white two colors having different charging polarities A white display medium comprising at least white particles containing at least titanium oxide and a charge control agent imparting negative chargeability; and black containing at least carbon black and a charge control agent imparting positive chargeability. An information display panel comprising: a black display medium containing at least particles.   An information display panel having a structure in which black and white two-color display media having different charging polarities are sealed between two opposing gas cavities in which at least one substrate is transparent, and the two opposing substrates A partition wall that keeps the gap between the substrates and partitions the space between the substrates is provided continuously or intermittently, and a black and white display medium is enclosed in a cell consisting of the partitioned gas space. In the information display panel having the above structure, a unit pixel is composed of three cells, and three color filters having three transparent primary colors are arranged on at least the substrate side which is the display surface side, and charging polarities are mutually connected. A white and black two-color display medium having at least white particles containing at least titanium oxide and a charge control agent imparting negative chargeability; and at least carbon black; Information display panel, wherein the black color display media comprising at least a black particles containing a charge control agent which imparts Las chargeability, that was formed from.   3. The information display panel according to claim 1, wherein the titanium oxide contained in the white particles constituting the white display medium having a negatively charged polarity is 10 parts by weight or more.   The information display panel according to claim 1 or 2, wherein the carbon black contained in the black particles constituting the black display medium having a positive charge polarity is 0.1 to 10 parts by weight.

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