JP2008139596A - Information display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information display panel having desired display quality by using particles for a display medium from which residual monomers are removed. <P>SOLUTION: The particles for a display medium, the particles constituting a display medium of an information display panel that displays information by applying an electric field to move the display medium sealed between substrates 1, 2, comprise polymer particles which are approximately spherical, obtained by a wet method and which contain a binder resin, an additive and a colorant. A part of or the whole monomers as a source material of the binder resin are crosslinking monomers. The additive comprises a copolymer of an acrylic resin and a hydrocarbon resin or a copolymer of acrylic resin and an acrylic resin having a hydrocarbon or a fluorinated hydrocarbon in a side chain. The polymer particle has a minute concavo-convex pattern uniformly distributed on the surface. The particles for a display medium show a heating loss of 1 wt.% or less by heating at 120°C for 4 hours. By using the above particles, an information display panel exhibiting desired display quality is obtained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention encloses a display medium having optical reflectivity and chargeability between two substrates, at least one of which is transparent, and applies an electric field to the display medium, thereby moving the display medium to obtain information such as an image. It is related with the information display panel which displays.

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

  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. In particular, recently, an electrophoretic method in which a dispersion liquid composed of dispersion particles and a colored solution is microencapsulated 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.

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

  As a method for solving the various problems described above, by encapsulating a display medium having optical reflectivity and chargeability between two substrates, at least one of which is transparent, and applying an electric field to the display medium, An information display panel that displays information such as an image by moving a display medium is known. In an information display panel of a type that displays information such as images by moving the display medium by such an electric field, the particle diameter of the display medium is about 1 to 50 μm in consideration of ease of movement. Since it becomes easy to secure the positive and negative chargeability and charge amount of the medium, acrylic resins, methacrylic resins, and styrene resins are used as the binder material for the display medium. As a method for producing such display medium particles (hereinafter, also referred to as particles), production using a pulverization method for simplifying the process, reducing energy consumption, or directly obtaining a target particle size. The production method using the wet method is more effective than the method, and the production method using suspension polymerization is more effective than the wet method.

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”, p.249-252

  When a wet method is used to obtain a binder resin by polymerizing monomers, the unreacted monomer remains at a certain rate, so these particles are used as display medium particles in information display panels. In this case, the residual monomer volatilized from the particles at a high temperature (for example, at 40 ° C.) may cause aggregation of the particles, which may deteriorate the display quality. In particular, in the case of particles having fine irregularities uniformly on the surface, the amount of monomer remaining in the gaps in the structure increases, and the amount of volatilization at high temperatures increases.

  An object of this invention is to provide the information display panel which has desired display quality by removing a residual monomer.

  In order to achieve the above object, the information display panel of the present invention encloses a display medium having optical reflectivity and chargeability between two substrates, at least one of which is transparent, and applies an electric field to the display medium. An information display panel that displays information such as an image by moving the display medium, and the display medium particles constituting the display medium are obtained by a wet method, are approximately spherical, binder resin, added A polymer particle containing an agent and a colorant, and a part or all of the monomer as a raw material of the binder resin is a crosslinkable monomer, and the additive is a copolymer of an acrylic resin and a hydrocarbon resin, Alternatively, it is a copolymer of an acrylic resin and an acrylic resin having a hydrocarbon or a fluorinated hydrocarbon in the side chain, and the polymer particles have uniform fine irregularities on the surface, and the display medium particles 20 ° C., heat loss in the heating for 4 hours to equal to or less than 1 wt%.

  As a preferred example of the information display panel of the present invention, the binder resin component constituting the polymer particles is selected from a plurality of types of monomers including at least an acrylic monomer and / or a styrene monomer. The polymerization of the above monomers, the glass transition temperature Tg of the resin constituting the display medium particles being 60 ° C. or higher, the average particle diameter of the display medium particles being 1 to 50 μm, the carrier The charge amount of the particles for display medium measured by the blow-off method using 10 may be 10 to 100 μC / g in absolute value, and the color of the particles for display medium may be white and / or black .

  According to the information display panel of the present invention, a display medium having optical reflectivity and chargeability is sealed between two substrates, at least one of which is transparent, and an electric field is applied to the display medium. The display medium particles constituting the display medium used in the information display panel for displaying information such as images by moving the image contains a substantially spherical binder resin, additive and colorant obtained by a wet method. A part or all of the monomer that is a raw material of the binder resin containing polymer particles is a crosslinkable monomer, and the additive is a copolymer of an acrylic resin and a hydrocarbon resin, or an acrylic resin and a side. It is a copolymer with an acrylic resin having a hydrocarbon or fluorinated hydrocarbon in the chain, and the polymer particles have uniform fine irregularities on the surface, and the display medium particles are 120 ° C. for 4 hours. Since heat loss in the heat is 1 wt% or less, the particles for display media becomes the residual monomer was removed. Therefore, it is possible to provide an information display panel that can express desired display quality.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  First, the configuration of the information display panel of the present invention using a display medium made of display medium particles will be described. In the information display panel of the present invention, an electric field is applied to a display medium sealed between two opposing substrates. Along with the applied electric field direction, the display medium is attracted by an electric field force or a Coulomb force, and the display medium is moved by a change in the electric field direction, whereby information such as an image is displayed. Therefore, it is necessary to design the information display panel so that the display medium can move uniformly and maintain the stability when the display information is rewritten or when the display information is continuously displayed. 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.

  Examples of the information display panel of the present invention will be described with reference to FIGS. 1 (a), 1 (b) to 4 (a), (b), and FIGS. 5 (a) to 5 (d).

  In the example shown in FIGS. 1A and 1B, at least two kinds of display media 3 (here, white particles 3Wa for display medium) having at least one kind of particles and having different optical reflectance and charging characteristics. The electrode 5 (individual electrode) provided on the substrate 1 in each cell formed by the partition walls 4 is provided with a white display medium 3W composed of a group of particles and a black display medium 3B composed of a group of black particles 3Ba for display medium. ) And an electrode 6 (individual electrode) provided on the substrate 2, the substrate 6 is moved perpendicularly to the substrates 1 and 2 according to an electric field generated by applying a voltage. Then, the white display medium 3W is visually recognized by the observer as shown in FIG. 1A, or white display is performed, or the black display medium 3B is visually recognized by the observer as shown in FIG. 1B. The display is black. In addition, in FIG. 1 (a), (b), the partition in front is abbreviate | omitted. The electrode may be provided outside the substrate, inside the substrate, or embedded in the substrate.

  In the example shown in FIGS. 2A and 2B, at least two or more kinds of display media 3 (here, white particles 3Wa for display medium) having different optical reflectance and charging characteristics composed of at least one kind of particles. The electrode 5 (line electrode) provided on the substrate 1 in each cell formed by the partition walls 4 is a white display medium 3W composed of a plurality of particles and a black display medium 3B composed of a black particle 3Ba for display medium. ) And an electrode 6 (line electrode) provided on the substrate 2, and is moved perpendicularly to the substrates 1 and 2 according to an electric field generated by applying a voltage. Then, the white display medium 3W is visually recognized by the observer as shown in FIG. 2A, or white display is performed, or the black display medium 3B is visually recognized by the observer as shown in FIG. 2B. The display is black. In addition, in FIG. 2 (a), (b), the partition in front is abbreviate | omitted. The electrode may be provided outside the substrate, inside the substrate, or embedded in the substrate.

  In the example shown in FIGS. 3 (a) and 3 (b), one type of display medium 3 (here, particles of white particles 3Wa for display medium) having optical reflectivity and chargeability composed of at least one type of particles. A white display medium 3W consisting of a group) in each cell formed by the partition walls 4, in accordance with the electric field generated by applying a voltage between the electrode 5 and the electrode 6 provided on the substrate 1, Move in the direction parallel to 1 and 2. Then, as shown in FIG. 3A, the white display medium 3W is visually recognized by the observer to display white, or the black plate 7 is visually recognized by the observer as shown in FIG. 3B. The display is black. In addition, in FIG. 3 (a), (b), the partition in front is abbreviate | omitted.

  In the example shown in FIGS. 4A and 4B, an example of color display in which a unit pixel is configured by three cells is shown. In the example shown in FIGS. 4A and 4B, as the display medium, the white display medium 3W and the black display medium 3B are enclosed in all of the cells 21-1 to 21-3, and the first cell 21-1. A red color filter 22R is provided on the viewer side, a green color filter 22G is provided on the viewer side of the second cell 21-2, a blue color filter 22B is provided on the viewer side of the third cell 21-3, A unit pixel is composed of three cells, the first cell 21-1, the second cell 21-2, and the third cell 21-3. In this example, when performing color display, as shown in FIG. 4A, the white display medium 3W is arranged in all of the first cell 21-1 to the third cell 21-3 on the viewer side. Thus, the white display is performed for the observer, or, as shown in FIG. 4B, the black display medium in all of the first cell 21-1 to the third cell 21-3 on the observer side. By arranging 3B, black display is performed for the observer. In addition, in FIG. 4 (a), (b), the partition in front is abbreviate | omitted. The electrode may be provided outside the substrate, inside the substrate, or embedded in the substrate.

  In the example shown in FIGS. 5A to 5D, first, as shown in FIGS. 5A and 5C, at least the optical reflectivity and charging characteristics of at least one kind of particles are different. Two or more types of display media 3 (here, a white display medium 3W composed of a group of white particles 3Wa for display medium and a black display medium 3B composed of a group of black particles 3Ba for display medium are shown) are formed by partition walls 4. In each of the formed cells, the substrate 1 corresponds to the electric field generated by applying a voltage between the external electric field forming means 11 provided outside the substrate 1 and the external electric field forming means 12 provided outside the substrate 2. 2 and move vertically. Then, the white display medium 3W is visually recognized by the observer as shown in FIG. 5B, or white display is performed, or the black display medium 3B is visually recognized by the observer as shown in FIG. 5D. The display is black. In addition, in FIG. 5 (a)-(d), the partition in front is abbreviate | omitted. A conductive member 13 is provided inside the substrate 1, and a conductive member 14 is provided inside the substrate 2.

  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.

  Hereinafter, the information display panel, which is a feature of the present invention, will be described in detail. In the information display panel of the present invention, a display medium is sealed between two substrates, at least one of which is transparent. The display medium particles constituting the display medium include a substantially spherical polymer particle containing a binder resin, an additive, and a colorant obtained by a wet method, and a monomer that is a raw material of the binder resin Is a crosslinkable monomer, and the additive is “a copolymer of an acrylic resin and a hydrocarbon resin” or “an acrylic resin having an acrylic resin and a hydrocarbon or a fluorinated hydrocarbon in a side chain” The polymer particles having fine irregularities uniformly on the surface thereof, and the weight loss of the display medium particles after heating at 120 ° C. for 4 hours is 1% by weight or less. ing. Here, as a method of setting the heating weight loss ratio indicating the decrease in weight after heating when heated at 120 ° C. for 4 hours to 1% or less of the weight before heating, for example, a display obtained by drying after suspension polymerization A method of removing residual monomers by further secondary drying the medium particles can be used. At that time, the resin component constituting the polymer particles is formed by polymerizing at least one monomer selected from a plurality of monomers including at least an acrylic monomer and / or a styrene monomer, the display The glass transition temperature Tg of the resin constituting the medium particles is 60 ° C. or higher, the average particle diameter of the display medium particles is 1 to 50 μm, and the display medium measured by a blow-off method using a carrier. It is preferable that the charge amount of the particles is 10 to 100 μC / g in absolute value, and that the color of the display medium particles is white and / or black.

  According to the information display panel of the present invention, for the display medium used in the information display panels of FIGS. 1 (a), 1 (b) to 4 (a), 4 (b) and 5 (a) to 5 (d). The particles include an approximately spherical polymer particle obtained by a wet method and containing a binder resin, an additive, and a colorant, and a part or all of a monomer that is a raw material of the binder resin is a crosslinkable monomer. The additive is “a copolymer of an acrylic resin and a hydrocarbon resin” or “a copolymer of an acrylic resin and an acrylic resin having a hydrocarbon or a fluorinated hydrocarbon in a side chain”, and the polymer The particles have fine irregularities uniformly on the surface, and the heat loss of the display medium particles after heating at 120 ° C. for 4 hours is 1% by weight or less. Will be properly removed and desired Information display panel capable of expressing a 示品 quality is obtained. In addition, the information display panels shown in FIGS. 1A, 1B, 4A, 4B, and 5A to 5D using the display medium particles are to be moved. Since there is no display medium remaining after the movement of the medium and there is no turbidity with another color, good display quality can be obtained.

  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 on which the color of the display medium can be confirmed from the outside of the panel, and a material having high visible light transmittance and good heat resistance is preferable. The back substrate as the other substrate may be transparent or opaque. Examples of substrate materials include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene (PE), polycarbonate (PC), polyimide (PI), polyethersulfone (PES), acrylic and other polymer sheets, metal Examples thereof include a flexible sheet such as a sheet and a non-flexible inorganic sheet such as glass and quartz. 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.

  Electrode forming materials for electrodes provided on the substrate as required include metals such as aluminum, silver, nickel, copper and gold, indium tin oxide (ITO), indium oxide, conductive tin oxide, antimony tin oxide (ATO). ), Conductive metal oxides such as conductive zinc oxide, and conductive polymers such as polyaniline, polypyrrole, and polythiophene are exemplified and used as appropriate. The electrode can be formed by patterning the above-described materials into a thin film by sputtering, vacuum deposition, CVD (chemical vapor deposition), coating, or the like, or by mixing a conductive agent with a solvent or synthetic resin binder. A method of applying and patterning 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 surface side substrate described above, but need not be transparent. In this case, the external voltage input may be superimposed with direct current or alternating current.

The shape of the partition provided on the substrate as required is appropriately set appropriately depending on the type of display medium involved in display, the shape of the electrode to be arranged, and the arrangement, and is not limited in general, but the width of the partition is 2 to 100 μm. The height of the partition wall is adjusted to 10 to 100 μm, preferably 10 to 50 μm.
In forming the partition wall, a both-rib method in which ribs are formed on each of the opposing substrates 1 and 2 and then bonded, and a single-rib method in which ribs are formed only on one substrate are conceivable. In the present invention, any method is preferably used.
As shown in FIG. 6, the cells formed by the partition walls made up of these ribs are exemplified by a square shape, a triangular shape, a line shape, a circular shape, and a hexagonal shape as viewed from the plane of the substrate. And a mesh shape. It is better to make the portion corresponding to the cross section of the partition wall visible from the display surface side (the area of the cell frame) as small as possible, and the display becomes clearer.
Examples of the method for forming the partition include a mold transfer method, a screen printing method, a sand blast method, a photolithography method, and an additive method. Any of these methods can be suitably used for an information display panel mounted on the information display device of the present invention, and among these, a photolithography method using a resist film and a mold transfer method are suitably used.

  Next, the powder fluid that is composed of particles for display medium and 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 used in the information display panel of the present invention, the present applicant has obtained the right of “Electronic Powder Fluid (registered trademark): Registration No. 4636931”.

  The “powder fluid” used as a display medium in the present invention is a substance in an intermediate state between fluid and particles 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 used as the display medium in the present invention is an intermediate state having both particle and liquid characteristics, similar to the definition of liquid crystal (intermediate phase between liquid and solid). It is a substance that is extremely resistant to the effects of gravity and that exhibits a unique state of 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 a solid substance is used as a dispersoid in an information display panel. is there.

The information display panel of the present invention encloses a powder fluid exhibiting high fluidity in an aerosol state in which solid particles are stably suspended as a dispersoid, for example, in a gas between opposing substrates, at least one of which is transparent. Yes, such powdery fluid is so fluid that it does not have an angle of repose, which is an index indicating the fluidity of the powder, and can be easily and stably moved by Coulomb force with a small electric field force. it can.
As described above, the powdered fluid is a substance in an intermediate state between the fluid and the particle, which exhibits fluidity by itself without borrowing the force of gas or liquid. This powder fluid can be in an aerosol state in particular, and in the information display panel of the present invention, it is used as a display medium in a state where a solid substance floats relatively stably as a dispersoid in the gas.

A method of charging the particles negatively or positively is not particularly limited, and a method of charging the particles such as a corona discharge method, an electrode injection method, and a friction method is used. It is preferable that the charge amount of particles measured by a blow-off method using a carrier is 10 to 100 μC / g in absolute value. When the absolute value of the charge amount is lower 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 is higher than this range, the mirror image force on the electrode and the substrate is too strong, and the memory property is good, but the follow-up movement of the display medium when the electric field is reversed becomes poor.
In the present invention, 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 is put into a cylindrical container with nets on both ends, and high-pressure gas is blown from one end to separate the display medium particles and carriers from the mesh opening. Only the particles for the 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 on the carrier. 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.
As a blow-off charge amount measuring device, TB-200 manufactured by Toshiba Chemical Corporation was used. In the present invention, a ferrite carrier is used for measuring the charge amount of the particles to be measured. The information display panel is composed of, for example, a display medium composed of positively chargeable display medium particles and a negatively chargeable display medium particle. When two types of display media are used in combination with the display media to be used, the same type of carrier is used when measuring the charge amount of the particles for the display media constituting each display medium. Specifically, the charge amount (μC / g) of the particles was measured using a DFC100 wrinkle (Mn—Mg-containing ferrite system) manufactured by Dowa Iron Powder Industry Co., Ltd. as a carrier.

Since the particles need to retain their charged charges, insulating particles having a volume resistivity of 1 × 10 ¹⁰ Ω · cm or more are preferable, and in particular, insulating particles having a volume resistivity of 1 × 10 ¹² Ω · cm or more. Is preferred. Further, particles having a slow charge decay property are more preferable.

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 display medium particles are composed of the display medium particles as they are to form a display medium, or are combined with other particles to form a display medium, or adjusted and configured to become a powder fluid to form a display medium. Or used.
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 addition, a resin polymerized in advance may be used, or a resin may be polymerized at the time of particle formation. Furthermore, it is good also as a copolymer using several types of resin raw materials at the time of superposition | polymerization. In particular, an acrylic resin, an acrylic fluororesin, a polystyrene resin, and a styrene acrylic resin are suitable from the viewpoint of controlling the adhesive force with the substrate and the ease of suspension polymerization.

  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 styrene acrylic resins having negatively charged functional groups. Examples of the positive charge control agent include nigrosine dyes, triphenylmethane compounds, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives, and styrene acrylic resins having positively charged functional groups. 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, resol 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. By blending the colorant, particles for a display medium having a desired color can be produced.

  The display medium particles (hereinafter also referred to as particles) used in the present invention have an average particle diameter d (0.5) in the range of 1 to 50 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 each particle, the particle size distribution Span represented by the following formula is less than 5, preferably less than 3.
Span = (d (0.9) −d (0.1)) / d (0.5)
(However, d (0.5) is a numerical value expressing the particle diameter in μm that 50% of the particles are larger than this and 50% is smaller than this, and d (0.1) is a particle in which the ratio of the smaller particles is 10%. (Numerical value expressed in μm, and d (0.9) is a numerical value expressed in μm for a particle diameter of 90% or less.)
By keeping Span within a range of 5 or less, the size of each particle is uniform, and movement as a uniform display medium becomes possible.

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

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

Furthermore, when a display medium composed of particles for a display medium is applied to an information display panel that is driven in an air space, it is important to manage the gas in the voids surrounding the display medium between the substrates, and display stability. Contributes to improved performance. 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.
This gap portion is a portion sandwiched between opposing substrates 1 and 2 in FIGS. 1A, 1B, 4A, 4B, and 5A to 5D. A so-called display medium excluding the electrodes 5 and 6 (when electrodes are provided inside the substrate), the occupied portion of the display medium 3, the occupied portion of the partition walls 4 (when provided with the partition walls), and the seal portion of the information display panel. It shall refer to the gas part in contact with.
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 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 specifically described with reference to examples and comparative examples of the present invention, but the present invention is not limited to the following. In addition, the information display panel of an Example and a comparative example evaluated the display panel for evaluation produced with the following method according to the following reference | standard.

<Comparative Example 1>
60 parts by weight of styrene monomer (Kanto Chemical Reagent) and 40 parts by weight of ethylene glycol dimethacrylate (Wako Pure Chemicals Reagent) as black positively charged particles, and nigrosine compound (Bontron N07: Orient as a positively charged monomer dispersion type charge control agent) (Chemical) 3 parts by weight and, as a black colorant, 5 parts by weight of carbon black (MA100: manufactured by Mitsubishi Chemical) were dispersed by a sand mill, and azobisisobutyronitrile (V- 60: manufactured by Wako Pure Chemical Industries, Ltd.) 2 parts by weight of the solution was suspended and polymerized in purified water to which 0.5% polyoxyethylene alkyl ether sodium sulfate (Latemul E-118B: manufactured by Kao Corporation) was added, polymerized, and filtered. Then, using a hot air oven, the dried powder dried at 100 ° C. for 2 hours is classified into a classifier (MDS-2: Nihon Nii Machikku Kogyo) were classified using to obtain particles 1 having an average particle diameter of 8.9 .mu.m. When the particles 1 were observed with a scanning microscope (SEM), it was confirmed that irregularities were formed on the surface. The resin component of Particle 1 had a Tg of 99 ° C. Moreover, the heating weight loss ratio which shows the reduction | decrease in the weight after a heating when this particle | grain 1 was heated at 120 degreeC for 4 hours was 1.3% of the weight before a heating.

  As white negatively charged particles, 60 parts by weight of styrene monomer (Kanto Chemical Reagent) and 40 parts by weight of ethylene glycol dimethacrylate (Wako Pure Chemicals Reagent) were added to a phenol-based condensate as a negatively charged monomer dispersion type charge control agent ( Bontron E89 (manufactured by Orient Chemical Co., Ltd.) 5 parts by weight and, as a white colorant, 80 parts by weight of titanium oxide (Taipaque CR-50: manufactured by Ishihara Sangyo) were dispersed by a sand mill, and further, polymerization initiator Azobis A solution in which 2 parts by weight of isobutyronitrile (V-60: manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved was added to purified water to which 0.5% sodium polyoxyethylene alkyl ether sulfate (Latemul E-118B: manufactured by Kao) was added. After suspending, polymerizing, and filtering, the dried powder dried at 100 ° C. for 2 hours using a hot air oven is classified into a classifier (MDS). 2: classified using the Nippon Pneumatic Mfg. Co.), to obtain particles 2 having an average particle diameter of 9.0μm. When the particles 2 were observed with a scanning microscope (SEM), it was confirmed that irregularities were formed on the surface. The Tg of the resin component of Particle 2 was 99 ° C. Moreover, the heating weight loss ratio indicating the decrease in the weight after heating when the particles 2 were heated at 120 ° C. for 4 hours was 1.2% of the weight before heating.

  A cell in which two kinds of display media composed of the above two kinds of particles are arranged via a spacer having a height of 50 μm, one of which is an inner ITO process and connected to a power source, and the other is a copper substrate. An information display panel was obtained by filling the inside with a volume ratio of 30% at the same ratio. When each of the ITO glass substrate and the copper substrate is connected to a power source, and a direct current voltage of 150 V is applied so that the ITO glass substrate is at a low potential and the copper substrate is at a high potential, the positively charged particles are at a low potential electrode. The negatively charged particles respectively moved to the high potential electrode, and a black solid display image could be observed through the glass substrate. Next, when the potential of the applied voltage was reversed, the display medium moved to the opposite polarity, and a white solid display image could be observed through the glass substrate. In any case, good display quality was obtained. However, when this information display panel was placed in a high temperature environment of 40 ° C. for 96 hours and subjected to a heat resistance test in which various evaluations were performed on the panel, particle aggregation was also observed by microscopic observation. For this reason, even if an evaluation similar to the above was performed, the particles did not move, and good display quality could not be obtained.

<Example 1>
As black positively charged particles, particles 3 of Comparative Example 1 were subjected to secondary drying at 100 ° C. for 1 hour to obtain particles 3. The average particle diameter of the particles 3 and the Tg of the resin component of the particles 3 were the same values as those of the particles 1. Further, the weight loss ratio indicating the decrease in weight after heating when the particles 3 were heated at 120 ° C. for 4 hours was 1.0% of the weight before heating.

  As white negatively charged particles, particles 4 of Comparative Example 1 were subjected to secondary drying at 100 ° C. for 1 hour to obtain particles 4. The average particle diameter of the particles 4 and the Tg of the resin component of the particles 4 were the same values as those of the particles 2. Moreover, the heating weight loss ratio indicating the decrease in the weight after heating when the particles 4 were heated at 120 ° C. for 4 hours was 0.8% of the weight before heating.

  A cell in which two kinds of display media composed of the above two kinds of particles are arranged via a spacer having a height of 50 μm, one of which is an inner ITO process and connected to a power source, and the other is a copper substrate. An information display panel was obtained by filling the inside with a volume ratio of 30% at the same ratio. When each of the ITO glass substrate and the copper substrate is connected to a power source, and a direct current voltage of 150 V is applied so that the ITO glass substrate is at a low potential and the copper substrate is at a high potential, the positively charged particles are at a low potential electrode. The negatively charged particles respectively moved to the high potential electrode, and a black solid display image could be observed through the glass substrate. Next, when the potential of the applied voltage was reversed, the display medium moved to the opposite polarity, and a white solid display image could be observed through the glass substrate. In any case, good display quality was obtained. Further, when the information display panel was placed in a high temperature environment of 40 ° C. for 96 hours and subjected to a heat resistance test for various evaluations, no aggregation of particles was observed. Also, when the same evaluation as described above was performed, the same good display quality was obtained.

<Example 2>
As black positively charged particles, particles 5 of Comparative Example 1 were subjected to secondary drying at 50 ° C. under reduced pressure for 12 hours to obtain particles 5. The average particle diameter of the particles 5 and the Tg of the resin component of the particles 5 were the same values as those of the particles 1. Moreover, the heating weight loss ratio which shows the reduction | decrease in the weight after a heating when this particle | grain 5 was heated at 120 degreeC for 4 hours was 0.3% of the weight before a heating.

  As white negatively charged particles, particles 6 of Comparative Example 1 were subjected to secondary drying at 50 ° C. under reduced pressure for 12 hours to obtain particles 6. The average particle diameter of the particles 6 and the Tg of the resin component of the particles 6 were the same as those of the particle 2. Moreover, the heating weight loss ratio indicating the decrease in the weight after heating when the particles 6 were heated at 120 ° C. for 4 hours was 0.3% of the weight before heating.

  A cell in which two kinds of display media composed of the above two kinds of particles are arranged via a spacer having a height of 50 μm, one of which is an inner ITO process and connected to a power source, and the other is a copper substrate. An information display panel was obtained by filling the inside with a volume ratio of 30% at the same ratio. When each of the ITO glass substrate and the copper substrate is connected to a power source, and a direct current voltage of 150 V is applied so that the ITO glass substrate is at a low potential and the copper substrate is at a high potential, the positively charged particles are at a low potential electrode. The negatively charged particles respectively moved to the high potential electrode, and a black solid display image could be observed through the glass substrate. Next, when the potential of the applied voltage was reversed, the display medium moved to the opposite polarity, and a white solid display image could be observed through the glass substrate. In any case, good display quality was obtained. Further, when the information display panel was placed in a high temperature environment of 40 ° C. for 96 hours and subjected to a heat resistance test for various evaluations, no aggregation of particles was observed. Also, when the same evaluation as described above was performed, the same good display quality was obtained.

The information display panel of the present invention includes a notebook computer, an electronic notebook, a portable information device called PDA (Personal Digital Assistants), a display unit of a mobile device such as a mobile phone, a handy terminal, an electronic book, an electronic newspaper, an electronic manual ( Electronic manuals), electronic paper such as signboards, posters, bulletin boards such as blackboards and whiteboards, electronic desk calculators, display units for home appliances, automobile supplies, card display units such as point cards and IC cards, electronic advertisements, In addition to information boards, electronic POPs (Point Of Presence, Point Of Purchase advertising), electronic price tags, electronic shelf labels, electronic musical scores, and display units for RF-ID devices, various electronic devices such as POS terminals, car navigation devices, watches, etc. It is suitably used for the display unit. In addition, it is also suitably used as rewritable paper (which can be rewritten using external electric field forming means).
The information display panel driving method according to the present invention includes a simple matrix driving method and a static driving method that do not use a switching element in the panel itself, and a three-terminal switching device or a thin film diode represented by a thin film transistor (TFT). Various types of driving methods such as an active matrix driving method using a two-terminal switching element represented by (TFD) and an external electric field driving method using an external electric field can be applied.

(A), (b) is a figure which shows the fundamental structure of the information display panel of this invention. (A), (b) is a figure which shows the fundamental structure of the information display panel of this invention. (A), (b) is a figure which shows the fundamental structure of the information display panel of this invention. (A), (b) is a figure which shows the fundamental structure of the information display panel of this invention. (A)-(d) is a figure which shows the principle structure 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.

Explanation of symbols

1, 2 Substrate 3 Display medium (particle group, powder fluid)
3W White display medium 3B Black display medium 3Wa White particles for display medium 3Ba Black particles for display medium 4 Bulkhead 5, 6 Electrode 7 Black plate 11, 12 External electric field forming means 13, 14 Conductive member 21-1 First cell 21- 2 Second cell 21-3 Third cell 22R Red color filter 22G Green color filter 22B Blue color filter

Claims (6)

Information for displaying information such as an image by moving a display medium by enclosing a display medium having optical reflectivity and chargeability between two substrates, at least one of which is transparent, and applying an electric field to the display medium A display panel,
The display medium particles constituting the display medium include polymer particles containing a substantially spherical binder resin, an additive, and a colorant, which are obtained by a wet method, and a monomer that is a raw material of the binder resin. A part or all of the monomer is a crosslinkable monomer, and the additive is a copolymer of an acrylic resin and a hydrocarbon resin, or an acrylic resin and an acrylic resin having a hydrocarbon or a fluorinated hydrocarbon in a side chain. It is a copolymer, and the polymer particles have fine irregularities uniformly on the surface, and the heating loss of the display medium particles at 120 ° C. for 4 hours is 1% by weight or less. Display panel.   The binder resin component constituting the polymer particles is formed by polymerizing at least one monomer selected from a plurality of types of monomers including at least an acrylic monomer and / or a styrene monomer. The information display panel according to claim 1.   3. The information display panel according to claim 1, wherein a glass transition temperature Tg of a resin constituting the display medium particles is 60 ° C. or higher.   4. The information display panel according to claim 1, wherein an average particle diameter of the display medium particles is 1 to 50 μm.   5. The information display panel according to claim 1, wherein a charge amount of the display medium particles measured by a blow-off method using a carrier is 10 to 100 μC / g in absolute value. .   The information display panel according to claim 1, wherein the color of the display medium particles is white and / or black.

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