WO2005103809A1

WO2005103809A1 - Process for producing particle for display medium, particle for display medium produced by the process, and information display unit utilizing the same

Info

Publication number: WO2005103809A1
Application number: PCT/JP2005/007638
Authority: WO
Inventors: Kazuya Murata; Takao Ohuchi; Hajime Kitano
Original assignee: Bridgestone Corporation
Priority date: 2004-04-22
Filing date: 2005-04-21
Publication date: 2005-11-03

Abstract

Particles for display medium for use in an information display unit comprising two opposed substrates at least one of which is transparent and, sealed therebetween, one or more types of display mediums wherein the display mediums are moved by an electric field generated in the substrates to thereby display images and other information. There are provided particles for display medium wherein those constituting at least one type of display medium among one or more types of display mediums are produced by suspension polymerization of particle raw materials including a monomer, and wherein a hardly soluble charge control agent is dispersed in the monomer prior to polymerization and thereafter suspension is effected with the use of a surfactant having two functional groups of polyoxyalkylene chain and sulfonic salt in each molecule as a suspension stabilizer.

Description

Specification

Method for producing particles for display medium, particles for display medium produced by the production method, and information display device using the same

Technical field

[0001] The present invention relates to a method of encapsulating one or more types of display media between two opposing substrates, at least one of which is transparent, and moving the display media by an electric field generated in the substrates to transfer information such as images. Method for producing display medium particles for producing display medium particles (hereinafter, sometimes referred to as particles) used for an information display device to be displayed, display medium particles produced by the production method, and the display medium The present invention relates to an information display device using particles for use.

Background art

[0002] Hitherto, information display devices using technologies such as an electrophoresis system, an electrochromic system, a thermal system, and a two-color particle rotation system have been proposed as information display devices replacing liquid crystal (LCD). .

[0003] These conventional technologies have advantages such as a wide viewing angle close to ordinary printed matter, low power consumption, and a memory function as compared with LCDs. It is considered as a technology that can be used for various information display devices, and is expected to be applied to information display for mobile terminals and electronic paper. In particular, recently, an electrophoresis method in which a dispersion liquid composed of dispersed particles and a coloring solution is microencapsulated and disposed between opposed substrates has been proposed and expected.

[0004] However, in the electrophoresis method, there is a problem that the response speed is reduced due to the viscous resistance of the liquid because particles migrate in the liquid. In addition, since particles of high specific gravity such as titanium oxide are dispersed in a solution of low specific gravity, sedimentation is likely to occur, and the stability of the dispersed state is difficult to maintain. Have In addition, even in the case of a micro cub, the cell size is set to the microcapsule level, and the above-mentioned drawbacks appear in the visual sense. , Na,.

[0005] On the other hand, in contrast to the electrophoresis method using behavior in a solution, a conductive particle is used without using a solution. A method of incorporating a carrier and a charge transport layer into a part of a substrate has begun to be proposed (for example, Guo Lao Zhao and three others, "New Toner Display Device (1)", July 21, 1999, Japan Image Annual conference (83 times in total), "Japan Hardcopy '99", pp.249-252. However, the arrangement of the charge transport layer and the charge generation layer complicates the structure, and it is difficult to inject charges uniformly into the conductive particles, which causes a problem of lack of stability.

[0006] As one method for solving the above-mentioned various problems, one or more types of display media are sealed between two opposing substrates, at least one of which is transparent, and an electric field generated in the substrates is used. 2. Description of the Related Art An information display device for displaying information such as an image by moving a display medium is known. In such an information display device of the type in which the display medium is moved, since the positive and negative characteristics of the particles for the display medium constituting the display medium and the charge amount can be easily secured, the acrylic resin and the methacrylic For example, particles for display media having a particle diameter of about 50 to 50 m manufactured using a monomer such as resin or styrene resin as a material for display medium particles are used.

[0007] As a method for producing particles for display media as described above, there are a method using pulverization and a method using suspension polymerization. However, the process is simplified, energy consumption is reduced, and a display medium having a target particle diameter is obtained. When particles are obtained directly, a method using suspension polymerization is more effective than a method using pulverization in order to achieve the above object. At that time, it is common to include a charge control agent soluble in the monomer for the purpose of controlling the charge amount and uniformly dispersing the charge in the particles. In addition, a polymer suspension stabilizer such as polyvinyl alcohol is generally used as a stabilizer during suspension polymerization, because the polymer suspension stabilizer is generally a low molecular weight suspension stabilizer. This is because the suspension stability is higher than that of the surfactant. Generally, these suspension stabilizers are present at the interface between the suspension in which the oil-based material such as a monomer has been turned into droplets and a suspension medium such as water.

[0008] In the case of using a monomer-soluble charge control agent when producing particles for a display medium, there arises a problem that a driving voltage for moving the particles during information display increases. The reason is that the charge in the particles is averaged out, and the particles for the display medium that can be driven at a low voltage are eliminated, so that the particles are induced by the particles for the display medium that can be driven at a low voltage, and other particles are generated. This is because, as a result, the particles for the display medium are not driven, so that the effect of reducing the driving voltage does not work.

[0009] When a polymer suspension stabilizer is used as a stabilizer during suspension polymerization, the amount of charge required as particles for a display medium used in a particle flying type information display device cannot be secured. The problem arises. The reason for this is that in the suspension polymerization method, the polymer suspension stabilizer is taken into the reaction system during polymerization and copolymerizes with the monomer at the particle interface, and as a result, it remains on the particle surface. This is because the charge amount of the hydrophilic functional particles due to the suspension stabilizer such as a hydroxyl group is reduced.

Disclosure of the invention

[0010] The first object of the present invention is to provide a manufacturing method for manufacturing particles for display media in which the driving voltage is reduced and the required charge amount as particles for display media is ensured. It is a second object of the present invention to provide an information display device using particles for a display medium which can reduce a driving voltage and secure a required charge amount.

[0011] In order to achieve the first object, the method for producing particles for display media of the present invention comprises enclosing at least one type of particles for display media between two opposing transparent substrates. A method for producing particles for display media, wherein the particles for display media are moved by an electric field generated in a substrate to produce particles for display media used in an information display device that displays information such as an image. At least one kind of the particles for the display medium among the particles for the display medium is particles for the display medium produced by suspension polymerization of a particle material containing a monomer, and After incorporating a poorly soluble charge control agent by dispersion, suspending using a surfactant having both a polyoxyalkylene chain and a sulfonate functional group in one molecule as a suspension stabilizer. Features.

[0012] The particles for display media of the present invention are characterized by being produced by the method for producing particles for display media described above.

[0013] In the particles for display media of the present invention, the resin component constituting the particles for display media is selected from neutrality of a plurality of monomers including at least an acrylic monomer, a methacrylic monomer and a styrene monomer. Is obtained by polymerizing one or more monomers, The glass transition temperature Tg of the resin constituting the particles for the display medium is 60 ° C. or higher, the average particle diameter of the particles for the display medium is 1 to 50 μm, and blow-off using a ferrite carrier. the surface charge density of the particles for display media measured by law is 10~ lOO ^ C / m ² in absolute value, the particles for display media is, release corona arranged at a distance of the particle surface and lmm When a voltage of 8 KV is applied to the electric appliance to generate a corona discharge to charge the particle surface, the maximum value of the particle surface potential after 0.3 seconds is a particle larger than 300 V, and the indication It is preferable that the medium particles have a white color and the display medium particles have a black color!

[0014] In order to achieve the second object, the information display device of the present invention comprises a display medium according to any one of the second to eighth inventions, wherein at least one of the two substrates is transparent. It is characterized by enclosing one or more kinds of particles for display and moving the particles for display medium by an electric field generated in the substrate to display information such as images.

According to the method for producing particles for a display medium of the present invention having the above structure, at least one type of display medium is sealed between two opposing substrates which are transparent, and generated in the substrates. When manufacturing particles for a display medium used in an information display device that displays information such as an image by moving a display medium by an electric field, at least one or more of the particles for a display medium are used for the display medium. The particles are particles for a display medium produced by suspension polymerization of a particle material containing a monomer, and after a charge control agent that is hardly soluble in the monomer before polymerization is dispersed, the suspension is stabilized. As a suspending agent, a surfactant having both a polyoxyalkylene chain and a sulfonate functional group in one molecule is used as a suspending agent, so particles are transferred when a monomer-soluble charge control agent is used. Drive voltage increases Problems, and the charge amount required as the particles for display media that occurs when using a polymeric suspension stabilizer is never able not become problems ensured as stabilizers when suspension polymerization. Accordingly, it is possible to provide a manufacturing method for manufacturing particles for display media in which the driving voltage for moving the particles is reduced and the charge amount required for the particles for display media is secured.

According to the particles for a display medium of the present invention, since the particles are produced by the method for producing particles for a display medium of the present invention, the driving voltage for moving the particles is reduced. In both cases, it is possible to provide particles for display media in which the required charge amount as particles for display media is secured.

According to the information display device of the present invention, the particles for a display medium according to any one of claims 2 to 8 are used as a display medium between two opposed substrates at least one of which is transparent. One or more types are enclosed, and the particles for display media are moved to display information such as images by generating them in the substrate.Therefore, the driving voltage for moving the particles is reduced and the required charge amount is increased. An information display device using particles for a display medium that can ensure the above can be provided.

Brief Description of Drawings

[FIG. 1] (a) and (b) are diagrams showing an example of an information display panel used in the information display device of the present invention.

2] (a) and (b) are diagrams showing another example of an information display panel used in the information display device of the present invention.

3] (a) and (b) are diagrams showing still another example of the information display panel used in the information display device of the present invention. [FIG.

FIG. 4 is a diagram showing an example of a shape of a partition wall in an information display panel of the information display device of the present invention.

FIG. 5 is a diagram showing a procedure for measuring the surface potential of particles used in the information display device of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

First, the configuration of an information display panel using particles for a display medium used in the information display device of the present invention will be described. In the information display panel of the present invention, an electric field is applied to the information display panel in which a display medium is sealed between the opposing substrates by some means. A display medium charged to a low potential is attracted by Coulomb force or the like in a direction of a high potential electric field, and a display medium charged to a high potential is attracted by a Coulomb force or the like in a direction of a low potential electric field. Information is displayed by changing the moving direction of these display media along the direction of the electric field. Therefore, it is necessary to design an information display panel so that the display medium can move uniformly and maintain stability during repetition or storage. Here, the particles for the display medium constituting the display medium In addition to the force attracting each other due to the Coulomb force between the particles, the force may be an electric image force with an electrode, an intermolecular force, a liquid bridging force, gravity, or the like.

An example of an information display panel provided in the information display device of the present invention will be described with reference to FIGS. 1 (a) and 1 (b) to 3 (a) and 3 (b).

In the examples shown in FIGS. 1 (a) and 1 (b), at least two or more types of display media 3 (here, white) having different optical reflectivities and charging characteristics are also configured, each of which has at least one type of particle force. The color display medium 3W and the black display medium 3B are moved perpendicularly to the substrate 2 according to the electric field applied from an electrode (not shown) arranged outside the substrate 2, and the black display medium 3B is observed. Either a black display is made by the viewer or a white display is made by making the viewer visually recognize the white display medium 3W. In the example shown in FIG. 1 (b), in addition to the example shown in FIG. 1 (a), for example, a partition wall 4 is formed in a lattice shape between the substrate 2 and the cell to form a cell. In addition, in FIG. 1 (b), a partition in the foreground is omitted.

In the examples shown in FIGS. 2 (a) and 2 (b), at least two or more types of display media 3 having different optical reflectances and charging characteristics (here, white The color display medium 3W and the black display medium 3B) are perpendicular to the substrate 2 according to the electric field generated by applying a voltage between the electrode 5 provided on the substrate 1 and the electrode 6 provided on the substrate 2. , The black display medium 3B is visually recognized by the observer to perform black display, or the white display medium 3W is visually recognized by the observer to perform white display. In the example shown in FIG. 2 (b), in addition to the example shown in FIG. 2 (a), for example, partition walls 4 are formed in a lattice shape between the substrate 2 and the cells to form cells. Also, in FIG. 2 (b), a partition wall in the foreground is omitted.

In the examples shown in FIGS. 3 (a) and 3 (b), one type of display medium 3 (here, white display medium 3W, (Shown) is moved in a direction parallel to the substrate 2 in accordance with the electric field generated by applying a voltage between the electrodes 5 and 6 provided on the substrate 1 so that the white display medium 3W is visually recognized by an observer. The color of the electrode 6 or the substrate 1 is displayed by displaying the color of the electrode 6 or the substrate 1 visually by an observer. In the example shown in FIG. 3 (b), in addition to the example shown in FIG. 3 (a), for example, grid-like partition walls 4 are provided between the substrates 1 and 2 to form cells. Also In FIG. 3 (b), the partition in front is omitted.

Hereinafter, a method for producing particles for a display medium constituting a display medium, which is a feature of the present invention, will be described in detail. In the method for producing particles for display media of the present invention, one or more types of display media are sealed between two opposing substrates, at least one of which is transparent, and the display media is moved by an electric field generated in the substrates. 1 (a), (b) to 3 (a), 3 (b), which are used to display information such as images. In order to achieve the objectives of reducing energy consumption and directly obtaining particles for display media having a desired particle size, a suspension polymerization method is used!

[0025] At least one kind of display medium particles among the one or more kinds of display medium particles sealed between the two substrates is formed by suspension polymerization of a particle material containing a monomer. Although the particles for display media are used, the neutral component of at least a plurality of types of monomers including at least an acrylic monomer, a methacrylic monomer, and a styrene monomer is also selected as the resin component constituting the particles for display media. By using at least one kind of monomer, particles for a display medium having a particle diameter of ~ are produced. At that time, in order to control the amount of charge and the state of charge, a charge control agent, which is hardly soluble in the monomer before polymerization, is contained by dispersion, and then, as a stabilizer during suspension polymerization, polyoxygen is contained in one molecule. Suspension is performed using a surfactant having both alkylene chain and sulfonate functional groups.

Therefore, according to the method for producing particles for a display medium of the present invention, the drive voltage for moving the particles increases as in the case of the particles for a display medium using a monomer-soluble charge control agent. Or the amount of charge required as particles for display media cannot be secured unlike the case of particles for display media using a polymer suspension stabilizer as a stabilizer during suspension polymerization. The drive voltage for moving the particles is reduced, and the particles for the display medium, in which the charge amount required for the particles for the display medium is secured, can be manufactured.

Hereinafter, each member constituting the information display device according to the present invention will be described.

Regarding the substrate, at least one substrate is a transparent substrate in which the color of particles 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. is there. The substrate on the back side can be either transparent or opaque. As an example of the substrate material, Examples include polymer sheets such as polyethylene terephthalate, polyethersulfone, polyethylene, polycarbonate, polyimide, and acrylic; flexible sheets such as metal sheets; and non-flexible inorganic sheets such as glass and quartz. Can be The thickness of the substrate is preferably 2 to 5000 μm, more preferably 5 to 2000 μm.If it is too thin, it is difficult to maintain strength and uniformity between the substrates.If it is more than 5000 / zm, it is thin. This is inconvenient when used as an information display panel.

[0029] As for the electrodes 5 and 6 provided as needed, the electrode 6 provided on the front substrate 2 side which is on the viewing side and needs to be transparent is formed of a transparent and patternable conductive material, For example, metals such as aluminum, silver, nickel, copper, and gold; transparent conductive metal oxides such as ITO, indium oxide, conductive tin oxide, and conductive zinc oxide; polyaline, polypyrrole, and polythiophene; These conductive polymers are exemplified and appropriately selected for use. Examples of the method of forming an electrode include a method of forming the above-described materials into a thin film by a sputtering method, a vacuum deposition method, a CVD (chemical vapor deposition) method, a coating method, or the like, or a method in which a conductive agent is mixed with a solvent or a synthetic resin binder. Or a method of applying. The thickness of the electrode is preferably 3 to: LOOO nm, and more preferably 5 to 4 OO nm, as long as the conductivity can be ensured and the light transmittance is not hindered. The material and thickness of the electrode 5 provided on the rear substrate 1 side are the same as those of the electrode 6 described above, but need not be transparent. In this case, the external voltage input may be superimposed on direct current or alternating current.

[0030] The shape of the partition wall 4 provided as required is optimally set as appropriate according to the type of the particle group involved in the display, and is not particularly limited, but the width of the partition wall is 2 to: LOO / zm or preferably 3 The height of the partition is adjusted to 10 to 500 μm, preferably 10 to 200 μm. Further, in forming the partition, a two-rib method in which ribs are formed on each of both opposing substrates and then joined, or a one-rib method in which ribs are formed only on one side of the substrate can be considered. In the present invention, any of the methods is suitably used.

As shown in FIG. 4, the cells formed by the ribs having the rib force are exemplified by a square, a triangle, a line, a circle, and a hexagon when viewed from the substrate plane direction. Examples of the shape include a honeycomb shape and a mesh shape. Display side force It is better to minimize the visible area (area of the cell frame) corresponding to the partition wall cross section. Increase. Here, examples of the method for forming the partition include a mold transfer method, a screen printing method, a sand blast method, a photolithographic method, and an additive method. Of these, a photolithography method using a resist film and a mold transfer method are preferably used.

Hereinafter, particles for a display medium (hereinafter, referred to as particles) used in the information display device of the present invention will be described. In the present invention, the display medium particles are negatively charged or positively charged colored particles, and any particles may be used as long as they move due to Coulomb force or the like.Particularly, spherical particles having a small specific gravity! is there.

[0033] The method for negatively or positively charging the particles is not particularly limited, and a method for charging the particles such as a corona discharge method, an electrode injection method, and a friction method is used. The surface charge density of the particles measured by a blow-off method using a ferrite carrier is preferably 10 to LOO μC / m ² in absolute value. If the absolute value of the surface charge density is lower than this range, the response speed to a change in the electric field becomes slow, and the memory property also becomes low. If the absolute value of the surface charge density is higher than this range, the image force on the electrode or the substrate is too strong, and the memory property is good, but the follow-up performance when the electric field is reversed is poor.

The measurement of the amount of charge and the measurement of the specific gravity of the particles necessary for obtaining the surface charge density used in the present invention were performed as follows.

<Blow-off measurement principle and measurement method>

In the blow-off method, a mixture of powder and carrier is placed in a cylindrical container having meshes at both ends, and the powder and carrier are separated by blowing high-pressure gas at one end, and only the powder is separated from the mesh opening. Blow off. At this time, a charge amount equal to and opposite to the charge amount that the powder has taken out of the container remains on the carrier. All of the electric flux due to this charge is collected in a Faraday cage, and the capacitor is charged by that amount. Then, by measuring the potential at both ends of the capacitor, the charge amount Q of the powder is

Q = CV (C: capacitance of capacitor, V: voltage across capacitor)

Is required.

As a blow-off powder charge amount measuring device, TB-200 manufactured by Toshiba Chemical Corporation was used. In the present invention, a ferrite-based carrier is used to measure the charge amount of the particles to be measured. When used in combination, the same type of carrier is used when measuring the charge amount of each display medium particle. Specifically, Dowa Iron Powder Industry Co., Ltd.

The charge amount of the particles (μC / g) was measured using DFC100 wrinkle (Mn-Mg-containing ferrite), and was calculated as the surface charge density of the particles from the particle density determined separately.

The particle specific gravity was measured with a Shimadzu Corporation hydrometer and a multi-volume density meter H1305.

[0034] particles, the so charged is necessary to hold the charge, volume resistivity 1 X ¹⁰ 10 Ω -cm or more insulating particles is preferably tool particularly volume resistivity 1 X 10 ¹² Ω 'cm or more Insulating particles are preferred. Further, particles having a slow charge decay property evaluated by the method described below are more preferable.

That is, the particles 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 an interval of 1 mm from the surface of the arranged particles to perform corona discharge. The generated particles are charged on the surface, and the change in the surface potential is measured and determined. In this case, it is important to select and prepare the particle constituting material so that the maximum value of the surface potential after 0.3 seconds is higher than 300 V, preferably higher than 400 V.

The measurement of the surface potential can be performed by, for example, an apparatus (CRT2000 manufactured by QEA) shown in FIG. In the case of this device, both ends of the shaft of the above-described needle-shaped measuring jig having the particles to be measured disposed thereon are held by chucks 21, and a small scorotron discharger 22 and a surface electrometer 23 are provided. A measurement unit with a predetermined distance is placed opposite to the surface of the particle to be measured at a distance of lmm, and the measurement unit is placed on the surface of the jig for roll measurement while the jig for roll measurement is stationary. A method of measuring the surface potential while giving a surface charge by moving the particle at one end to the other end at a constant speed is preferably adopted. The measurement environment is temperature 25 ± 3 ° C and humidity 55 ± 5RH%.

[0037] The particles may be composed of any material as long as the charging performance and the like are satisfied. For example, a resin, a charge control agent, a coloring agent, an inorganic additive, and the like can be formed. As the particles, those having a glass transition temperature Tg of the resin constituting the particles of 60 ° C or more are preferably used. Good. The particles can contain a charge control agent, a coloring agent, an inorganic additive, and the like in the resin as a main component, as in the conventional case. Examples of resins, charge control agents, coloring agents, and other additives are described below.

[0038] Examples of the resin include urethane resin, urethane resin, acrylic resin, polyester resin, acrylic urethane resin, acrylic urethane silicone resin, acrylic urethane fluorine resin, acrylic fluorine resin, Silicone resin, acrylic silicone resin, epoxy resin, polystyrene resin, styrene acrylic resin, polyolefin resin, butyral resin, vinylidene chloride resin, melamine resin, phenol resin, fluorine resin, polycarbonate. Fat, polysulfone resin, polyether resin, polyamide resin, and the like, and two or more kinds can be mixed. In particular, from the viewpoint of controlling the adhesion to the substrate, acrylic urethane resin, acrylic silicone resin, acrylic fluorine resin, acrylic urethane silicone resin, acrylic urethane fluorine resin, fluorine resin, silicone resin. Is preferred.

[0039] In addition to the charge control agent used in the present invention, the charge control agent used as needed is not particularly limited. Examples of the negative charge control agent include a salicylic acid metal complex, a metal-containing azo dye, Oil-soluble dyes containing metals (including metal ions and metal atoms), quaternary ammomium-based compounds, Rick's allylene conjugates, boron-containing compounds (boron benzylate complex), nitroimidazole derivatives, etc. No. Examples of the positive charge control agent include a nig mouth dye, a triphenylmethane compound, a quaternary ammonium salt compound, a polyamine resin, and an imidazole derivative. In addition, metal oxides such as ultrafine silica, ultrafine titanium oxide and ultrafine alumina, nitrogen-containing cyclic compounds such as pyridine and derivatives and salts thereof, various organic pigments, and resins containing fluorine, chlorine, nitrogen, etc. Is also used as a charge control agent.

[0040] As the colorant, various kinds of organic or inorganic pigments and dyes as exemplified below can be used.

[0041] Examples of the black colorant include carbon black, copper oxide, dimanganese diacid, arin black, activated carbon and the like.

Blue colorants include CI Pigment Blue 15: 3, CI Pigment Blue 15, dark blue, cobalt blue, alkali blue lake, Victoria blue lake, and phthalocyanine. Blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, First Sky Blue, Indanthrene Blue BC and the like.

Red colorants include Bengala, Cadmium Red, Lead Tan, Mercury Sulfide, Cadmium, Permanent Red 4R, Linole Red, Pyrazolone Red, Watching Red, Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Aliza Lin Lake, Brilliant Carmine 3B, CI Pigment Red 2, etc.

[0042] Examples of the yellow colorant include graphite, zinc yellow, cadmium yellow, yellow iron oxide, mineral yellow, nickel yellow titanium yellow, nev no yellow, naphtho no yellow yellow S, nonzai yellow G, hanzi yellow 10G, benzidine Yellow G, Benzijin Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, CI Pigment Yellow 12 and others.

Examples of the green colorant include chrome green, oxidized chromium, pigment green B, CI pigment green 7, malachite green lake, and huainanorayello green G. Orange colorants include red lead, molybdenum orange, permanent orange GTR, pyrazolone age range, norecan age range, indanthrene brilliant age range RK :, benzidine age range G, indanthrene brilliant age range GK, CI Pigment Age Range 3 1 mag.

Purple colorants include manganese violet, first violet B, methyl violet lake, and the like.

Examples of white colorants include zinc white, titanium oxide, antimony white, zinc sulfate, and the like.

[0043] Examples of the extender include norite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white. Various dyes such as basic, acidic, disperse and direct dyes include Nigguchi Shin, 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, and cadmium. Orange, titanium yellow, navy blue, ultramarine, cobalt blue, cobalt green, cobalt violet, iron oxide, carbon black, manganese black Elite black, cobalt ferrite black, copper powder, aluminum powder, and the like. These pigments and inorganic additives can be used alone or in combination. Of these, carbon black is particularly preferred as the black pigment, and titanium oxide is preferred as the white pigment.

The particles used in the present invention preferably have an average particle diameter d (0.5) in the range of 1 to 50 μm, and are preferably uniform. If the average particle diameter d (0.5) is larger than this range, the display lacks sharpness. If the average particle diameter d (0.5) is smaller than this range, the cohesive force between the particles becomes too large, which hinders the movement of the particles.

Further, in the present invention, regarding the particle size distribution of each particle, the particle size distribution Span represented by the following formula is set to less than 5, preferably less than 3.

Span = (d (0.9) -d (0.1)) /d(0.5)

(However, d (0.5) is the numerical value of the particle diameter in which 50% of the particles are larger and 50% is smaller than this, expressed in m, and d (0.1) is the particle in which the ratio of particles smaller than 10% is 10%.) The particle diameter is expressed as / zm, and d (0.9) is the particle diameter at which 90% of the particles are 90% or less./zm.) By setting the Span within the range of 5 or less, The size is uniform and uniform particle movement is possible.

[0047] Further, regarding the correlation of each particle, of the particles used, the ratio of d (0.5) of the particle having the minimum diameter to d (0.5) of the particle having the maximum diameter is 50 or less, preferably 10 or less. It is important to do so. Even if the particle size distribution Span is reduced, particles with different charging characteristics move in opposite directions, so that particles with similar particle sizes can easily move in opposite directions by an equivalent amount. It is preferable that the force falls within this range.

[0048] The above-mentioned particle size distribution and particle size can be determined by a laser diffraction Z scattering method or the like. When laser light is applied to the particles to be measured, a spatial light intensity distribution pattern of the diffracted Z scattered light is generated, and since this light intensity pattern has a correspondence with the particle size, the particle size and the particle size distribution are measured. it can.

Here, the particle size and the particle size distribution in the present invention are obtained from a volume-based distribution. Specifically, using a Mastersizer2000 (Malvern Instruments Ltd.) measuring machine Then, the particles are put into a nitrogen stream, and the particle size and particle size distribution can be measured by the attached analysis software (software based on volume-based distribution using Mie theory).

Further, in the present invention, it is important to control the gas in the gap surrounding the display medium between the substrates, which contributes to the improvement of display stability. Specifically, it is important that the relative humidity at 25 ° C of the gas in the voids be 60% RH or less, preferably 50% RH or less, and more preferably 35% RH or less. .

In FIGS. L (a) and (b) to FIGS. 3 (a) and 3 (b), the gap portion is defined as a portion sandwiched between the opposing substrates 1 and 2, and the electrodes 5 and 6 (the electrodes are placed inside the substrate). Excluding display medium 3, occupied portion of display medium 3, occupied portion of partition 4 (when partition is provided), excluding information display panel seal portion V,,, V, refers to gas portion in contact with so-called display medium And

The type of gas in the void portion is not limited as long as it is in the humidity range described above, but dry air, dry nitrogen, dry argon, dry helium, dry carbon dioxide, dry methane and the like are preferable. This gas needs to be sealed in the information display panel so that its humidity is maintained.For example, filling of the display medium, assembling of the information display panel, etc. are performed in a predetermined humidity environment. It is important to provide a sealing material and a sealing method to prevent external moisture from entering the humidity.

[0050] The distance between the substrates in the information display panel of the information display device of the present invention is not particularly limited as long as the display medium can be moved and the contrast can be maintained, but is usually 10 to 500 m, preferably 10 to 500 m. Adjusted to 200 μm.

The volume occupancy 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%, movement of the display medium (particles for display medium) is hindered, and if it is less than 5%, the contrast tends to be unclear.

Example

Hereinafter, the present invention will be described more specifically with reference to Examples of the present invention. However, the present invention is not limited to the following. In the following examples, particles for a display medium which can be used for the information display panel shown in FIGS. 1 (a) and 1 (b) to 3 (a) and 3 (b) were manufactured.

Methyl methacrylate monomer (manufactured by Kanto Chemical Reagent) 95mol% And trimethylolpropane triatalylate (A-TMPT: Shin-Nakamura-Danigaku) 5 mol%, as a positively-charged monomer poorly-soluble charge control agent-Grosiny-Danied product (Bontron N07: Orient Chemical) 3 parts by weight Also, as a surfactant, a liquid in which 5 parts by weight of carbon black (special black 5: Degussa) as a black pigment is dispersed by a sand mill and 2 parts by weight of lauryl baroxide (Paryl L: manufactured by NOF Corporation) is dissolved is used as a surfactant. Sodium polyoxyethylene alkyl ether sulfate (Latemul E-118B: manufactured by Kao) is suspended and polymerized in purified water containing 0.5% carohydrate, filtered and dried, and then classified, (MD S-2: Japan -Umatic Industrial Co., Ltd.) to obtain particles having a particle size range of 5 to 20 μm. The charge amount of the obtained particles was +80 μC / r, and the maximum value of the surface potential 0.3 seconds after the surface potential measurement was 470 V. The T g (glass transition temperature) of the resin component of the particles was 102 ° C.

[0053] The negatively-chargeable particles include a styrene monomer (manufactured by Kanto Chemical Reagents) 95mol% and trimethylolpropane triatalylate (A-TMPT: Shin-Nakamura Idanagaku) 5mol%, and a negatively charged monomer-soluble charge. 5 parts by weight of an acrylic charge control agent (Ataribase FCA1001N S: manufactured by Fujikura Kasei) as a control agent and 20 parts by weight of titanium oxide (Taipeta CR-50: manufactured by Ishihara Sangyo) as a white pigment were dispersed by a sand mill. A liquid in which parts by weight of lauryl peroxide (Paryl L: manufactured by Nippon Oil & Fats) are dissolved is added to 0.5% of purified water containing 0.5% sodium polyoxyethylene alkyl ether sulfate (Latemul E-118B: manufactured by Kao) as a surfactant. After suspending and polymerizing, and further filtering and drying, the particles are classified using a classifier (MD S-2: manufactured by Japan-Umatic Co., Ltd.) to obtain a particle size range. Particles with a range of 5-20 m were obtained. The charge amount of the obtained particles was 70 CZm ² , and the maximum value of the surface potential was 0.3 V after 0.3 seconds from the surface potential measurement. The T g (glass transition temperature) of the resin component of the particles was 95 ° C.

[0054] The positively chargeable particles and the negatively chargeable particles were charged by frictionally charging the particles by mixing and stirring equivalent amounts of both particles.

The mixed particles of the positively chargeable particles and the negatively chargeable particles are placed on two substrates (one of which is a glass substrate on which an inner ITO treatment is performed, and the other of which is a copper substrate) arranged through a 100 m spacer. Is filled at a volume occupancy of 30% to form an information display panel. Configured. When each of the ITO glass substrate and the copper substrate is connected to a power source, and ΙΤΟ a DC voltage of 250 V is applied so that the glass substrate has a low potential and the copper substrate has a high potential, the positively-charged particles become low potential poles. The negatively-charged particles flew to the high-potential pole side, and the information display panel observed through the glass substrate was displayed in black. Next, ΙΤΟ When a DC voltage of 250 V, which is reversed so that the glass substrate becomes high potential and the copper substrate becomes low potential, is applied, the positively charged particles fly to the high potential pole side and the negatively charged particles The information display panel that flew to the low potential pole side and was observed through the glass substrate was displayed in white. The reflectances during white display and black display were measured, and the ratio of the reflectance during white display and black display was determined. Furthermore, the potential of the DC voltage to be applied is changed, black display and white display are performed in the same manner as described above, the reflectance at white display and black display is measured, and the reflectance at white display and the black display are measured. The ratio with respect to the reflectance was determined. Based on the above measurement results, the drive voltage in Example 1 was determined when “the voltage at which the ratio of the reflectance in white display to the reflectance in black display becomes eight times” is defined as “drive voltage”. As a result, the drive voltage was 120 V.

Positively-chargeable particles include a positively charged monomer-soluble monomer in 95 mol% of methyl methacrylate monomer (manufactured by Kanto Chemical Reagents) and 5 mol% of trimethylolpropane triatalylate (A-TMPT: manufactured by Shin-Nakamura Idani) After dissolving 5 parts by weight of an acrylic resin charge control agent (Ataribase FCA21PS: Fujikura Kasei) as a control agent, 5 parts by weight of a carbon black (Special Black 5: Degussa) as a black pigment is sand-milled. And a liquid in which 2 parts by weight of lauryl peroxide (Peryl L: manufactured by Nippon Oil & Fats) is dissolved. Sodium polyoxyethylene alkyl ether sulfate (Latemul E-118B: manufactured by Kao) is used as a surfactant. After suspending and polymerizing in purified water to which 5% has been added, further filtering and drying, the mixture is classified using a classifier (MDS-2: manufactured by Japan-Umatic Co., Ltd.). By and this range of particle diameter to obtain particles of 5 to 20 mu m. The charge amount of the obtained particles was +82 μθ / να, and the maximum value of the surface potential 0.3 seconds after the surface potential measurement was 470 V. The Tg (glass transition temperature) of the resin component of the particles was 100 ° C.

As the negatively chargeable particles, the same particles as those in Example 1 were used. The charging of the positively chargeable particles and the negatively chargeable particles was carried out by mixing and stirring equivalent amounts of both particles to frictionally charge the particles.

The mixed particles of the positively chargeable particles and the negatively chargeable particles are placed on two substrates (one of which is a glass substrate on which an inner ITO treatment is performed, and the other of which is a copper substrate) arranged through a 100 m spacer. Was filled at a volume occupancy of 30% to form an information display panel. When each of the ITO glass substrate and the copper substrate is connected to a power source and a DC voltage of 250 V is applied so that the ITO glass substrate has a low potential and the copper substrate has a high potential, the positively-charged particles become low potential poles. The negatively-charged particles flew to the high-potential pole side, and the information display panel observed through the glass substrate was displayed in black. Next, when a DC voltage of 250 V, which is reversed so that the ITO glass substrate has a high potential and the copper substrate has a low potential, is applied, the positively-charged particles fly to the high-potential electrode side and move to the negatively-charged particle side. Flew to the low potential electrode, and the information display panel observed through the glass substrate was displayed in white. The reflectance in white display and black display was measured, and the ratio of the reflectance in white display to the reflectance in black display was determined. Further, the potential of the DC voltage to be applied is changed, black display and white display are performed in the same manner as described above, the reflectance at white display and black display are measured, and the reflectance at white display and the black display are measured. The ratio with respect to the reflectance was determined. Based on the above measurement results, the drive voltage in Comparative Example 1 was determined when “the voltage at which the reflectance ratio between white display and black display becomes eight times” was defined as “drive voltage”. The working voltage was 230 V, which was a large driving voltage almost twice that of the first embodiment.

Positively-chargeable particles include a methylmetharylate monomer (manufactured by Kanto Chemical Reagents) 95 mol% and trimethylolpropane triatalylate (A-TMPT: Shin-Nakamura-Danigaku) 5 mol%. 3 parts by weight of -Grosiny conjugate (Bontron N07: manufactured by Orient Chemical) as a control agent and 5 parts by weight of carbon black (Special Black 5: manufactured by Degussa) as a black pigment are dispersed by a sand mill, and 2 parts by weight of lauryl vero is further dispersed. The liquid in which oxide (Paroil L: Nippon Oil & Fat) was dissolved was suspended and polymerized in purified water containing 0.5% sodium dodecyl sulfate (Kanto Chemical Reagents) as a surfactant. Lump formed when the monomer components However, it was difficult to obtain good particles.

Positively-chargeable particles include a methylmetharylate monomer (manufactured by Kanto Chemical Reagents) 95 mol% and trimethylolpropane triatalylate (A-TMPT: Shin-Nakamura-Danigaku) 5 mol%. 3 parts by weight of -Grosiny conjugate (Bontron N07: manufactured by Orient Chemical) as a control agent and 5 parts by weight of carbon black (Special Black 5: manufactured by Degussa) as a black pigment are dispersed by a sand mill, and 2 parts by weight of lauryl vero is further dispersed. A liquid in which quicide (Paroil L: manufactured by Nippon Oil & Fats) is dissolved is added to a purified water prepared by adding 0.5% of a polyvinyl alcohol suspension stabilizer (Bhopal PVA-420: manufactured by Kuraray) as a surfactant. After suspending and polymerizing, further filtering and drying, the particles are classified using a classifier (MDS-2: manufactured by Nippon Pneumatic Industries, Ltd.) to obtain a particle size range. Yielded particles of 5-20 m. The charge amount of the obtained particles was +2 CZm ² , and the maximum value of the surface potential 0.3 seconds after the measurement of the surface potential was 25 V. The Tg (glass transition temperature) of the resin component of the particles was 102 ° C.

As the negatively chargeable particles, the same particles as those in Example 1 were used.

[0059] The positively chargeable particles and the negatively chargeable particles were charged by frictionally charging the particles by mixing and stirring equivalent amounts of both particles.

The mixed particles of the positively chargeable particles and the negatively chargeable particles are placed on two substrates (one of which is a glass substrate on which an inner ITO treatment is performed, and the other of which is a copper substrate) arranged through a 100 m spacer. Was filled at a volume occupancy of 30% to form an information display panel. Each of the ITO glass substrate and the copper substrate is connected to a power source, and a DC voltage of 250 V is applied so that the ITO glass substrate has a low potential and the copper substrate has a high potential.White particles and black particles are not separated. And a good display state could not be obtained.

As is clear from the above, only the particles for the display medium of Example 1 became particles for the display medium in which the driving voltage was reduced and the charge amount required for the particles for the display medium was secured.

The reasons are as follows: (1) The raw material of the particles for display media produced by suspension polymerization contains a charge control agent that is hardly soluble in the above monomers, and the charge control agent that is hardly soluble remains solid. (2) Suspension using a surfactant having both polyoxyalkylene chain and sulfonate functional groups in one molecule as a stabilizer during suspension polymerization. , And the like. According to (1), the charge control agent in the particles for the display medium is microscopically localized, causing non-uniform charging. Therefore, particles for the display medium partially including components driven at a low voltage are manufactured. Will be done. In addition, according to (2), by having a polyoxyalkylene chain in the molecule, a suspension stabilizing effect similar to that of a polymer system can be obtained, and it is structurally inert to the reaction system during polymerization. After the polymerization, the particles are washed away by sufficient washing, and the chargeability of the particles as a product is not impaired. In addition, by having a sulfonate as a functional group in the molecule, a polarity difference occurs in the functional group in the molecule, a surfactant effect is obtained, and the suspension stability is further increased.

Industrial applicability

The information display panel and the information display device using the particles for the display medium manufactured by the manufacturing method of the present invention are used for display units of electronic devices such as notebook personal computers, PDAs, mobile phones, and handy terminals, electronic books, electronic newspapers, etc. Electronic paper, signboards, posters, blackboards and other bulletin boards, calculators, home appliances, display parts for automotive supplies, etc., card displays for point cards, IC cards, etc., electronic advertising, electronic POP, electronic price tags, electronic shelf labels, electronic It is suitably used for musical scores, display sections of RF-ID devices, etc.

Claims

The scope of the claims

[1] At least one type of display medium is sealed between two opposing substrates, at least one of which is transparent, and information such as images is displayed by moving the display medium by an electric field generated in the substrate. A method for producing particles for display media for producing particles for display media used in an apparatus, comprising:

At least one kind of the particles for the display medium among the particles for the display medium is a particle for the display medium produced by suspension polymerization of a particle material containing a monomer, and is hardly soluble in the monomer before polymerization. After the addition of a charge control agent by dispersion, it is suspended using a surfactant having both a polyoxyalkylene chain and a sulfonate functional group in one molecule as a suspension stabilizer. Of producing particles for display media.

[2] A particle for a display medium produced by the method for producing particles for a display medium according to claim 1.

[3] The resin component constituting the particles for the display medium is formed by polymerizing at least one monomer selected from the group consisting of at least neutral monomers including acrylic monomers, methacrylic monomers and styrene monomers. 3. The particles for a display medium according to claim 2, wherein the particles are formed.

4. The particles for display media according to claim 2, wherein the resin constituting the particles for display media has a glass transition temperature Tg of 60 ° C. or higher.

[5] The display medium according to claim 2, wherein the average particle diameter of the particles is 1 to 50 μm.

5. The particles for a display medium according to any one of items 4 to 4.

[6] The method according to any one of claims 2 to 5, wherein the surface charge density of the particles for a display medium measured by a blow-off method using a ferrite carrier is 10 to LOO μCZm ² in absolute value. Or particles for display media according to item 1.

[7] When the particles for the display medium are charged with a voltage of 8 KV to generate a corona discharge by applying a voltage of 8 KV to a corona discharger arranged at an interval of 1 mm from the particle surface, the particle surface is charged. The particles for a display medium according to any one of claims 2 to 6, wherein the particles have a maximum value of the particle surface potential after 3 seconds which is larger than 300V.

[8] The method according to any one of claims 2 to 7, wherein the color of the particles for a display medium is white. The particles for a display medium according to the above.

[9] The particles for a display medium according to any one of claims 2 to 7, wherein the color of the particles for a display medium is black.

[10] At least one type of display medium comprising the particles for display medium according to any one of claims 2 to 9 is sealed between two opposing substrates, at least one of which is transparent, and the substrate is enclosed in the substrate. An information display device characterized by displaying information such as an image by moving a display medium by the generated electric field.