JP2006163076A - Manufacturing method for particle for display medium, particle for display medium, and panel for information display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for particles for a display medium with which a panel for information display panel free of degradation in display contrast and response speed, excellent in durability of repetitive displaying and rewriting of information, is obtained, and also to provide the particles for the display medium, and the panel for information display. <P>SOLUTION: In the manufacturing method for the particles for the display medium that constitute the display medium used for the panel for information display which displays information of an image etc., by moving the display medium by charging the display medium between two opposite substrates at least one of which is transparent and applying an electric field to the display medium, a metal compound is formed on particle surfaces by a sputtering method. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information display panel for displaying information such as an image by moving a display medium by enclosing a display medium between two opposing substrates, at least one of which is transparent, and applying an electric field to the display medium. The present invention relates to a method for producing particles constituting a display medium used in the above, a display medium particle obtained by the production method, and an information display panel using the display medium particle.

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

  Compared to LCDs, these conventional technologies have advantages such as a wide viewing angle close to that of ordinary printed materials, low power consumption, and a memory function. It is considered as a technology that can be used for mobile phones, and is expected to expand to information display for mobile terminals, electronic paper, and the like. Particularly recently, an electrophoretic method in which a dispersion liquid composed of dispersed particles and a colored solution is encapsulated and disposed between opposing substrates has been proposed and is expected.

  However, the electrophoresis method has a problem that the response speed becomes slow due to the viscous resistance of the liquid because the particles migrate in the liquid. In addition, since particles with high specific gravity such as titanium oxide are dispersed in a solution with low specific gravity, it is easy to settle, and it is difficult to maintain the stability of the dispersed state, and there is a problem that the stability of repeated information display is lacking. ing. Even when microencapsulation is performed, the cell size is set to the microcapsule level, and the above-described drawbacks are hardly made to appear, and the essential problems are not solved at all.

  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, the structure is complicated because the charge transport layer and further the charge generation layer are arranged, and it is difficult to uniformly inject the charge into the conductive particles.

As a method for solving the various problems described above, after encapsulating a display medium between two opposing substrates, at least one of which is transparent, an electric field is applied to the display medium, and the display medium is moved to generate an image, etc. There is known an information display panel for displaying the above information.
趙 Kuniori and three others, “New Toner Display Device (I)”, July 21, 1999, Annual Meeting of the Imaging Society of Japan (83 times in total) “Japan Hardcopy'99” Proceedings, p.249-252

  In the information display panel described above, conventionally, particles produced by pulverizing and classifying resin have been used as a display medium as a particle group in a state as they are. In recent years, a fine particle group having a fluidity-modifying effect is mixed with the above particle group, and a fine particle adhered around the particle has been used as a display medium. Although this display medium can obtain a certain degree of fluidity modification effect, the fluidity modification effect is manifested only in the initial stage, and is repeatedly used as a display medium (rewrite for information display is repeated). In other words, when the display medium is driven), there is a problem that the driving cannot be performed gradually. Further, when the display medium is repeatedly driven, there is a problem that the fine particles adhering to the particles are detached and the display contrast is lowered and the response speed is lowered.

  The present invention eliminates the above-mentioned problems, does not cause a decrease in display contrast or response speed, and can provide a display medium particle having good durability, a display medium particle manufacturing method, and display medium particle and information. It is intended to provide a display panel.

  The present invention relates to an information display panel for displaying information such as an image by moving a display medium by enclosing a display medium between two opposing substrates, at least one of which is transparent, and applying an electric field to the display medium. In the method for producing a display medium particle constituting the display medium used in the above, a metal compound is formed on the particle surface by a sputtering method.

  In addition, as a suitable example of the method for producing display medium particles of the present invention, a plurality of types of display media may be used when producing a plurality of types of display medium particles constituting a plurality of types of display media enclosed in the same information display panel. A metal compound is simultaneously formed on the surface of a plurality of types of display medium particles constituting the medium by a sputtering method, the metal compound is a metal oxide, a metal nitride, or a metal oxynitride, a metal oxide Has a main composition of silicon oxide or titanium oxide, and a metal oxynitride has a main composition of silicon oxynitride or titanium oxynitride. Here, the main composition of silicon oxide or titanium oxide means that not only silicon oxide or titanium oxide, but also doping of some other elements and deficiency in the degree of oxidation are included. Similarly, the main composition of silicon oxynitride or titanium oxynitride means that not only silicon oxynitride or titanium oxynitride but also doping of some other elements and lack of oxidation degree are included.

  The display medium particles of the present invention are characterized by being produced according to the production method described above. Furthermore, the information display panel of the present invention is characterized by using the above-mentioned display medium particles as a particle group or a powder fluid.

  According to the present invention, particles for a display medium can be obtained by forming a metal compound on the particle surface by a sputtering method so that an information display panel having good durability can be obtained without a decrease in display contrast and response speed. Can be manufactured.

  First, the basic configuration of the information display panel of the present invention will be described. In the information display panel of the present invention, an electric field is applied to a display medium sealed between two opposing substrates. Along with the applied electric field direction, the charged display medium is attracted by the electric field force or Coulomb force, etc., and the display medium reciprocates due to the change of electric field direction due to the potential change, thereby displaying information such as an image. Made. Therefore, it is necessary to design the information display panel so that the display medium moves uniformly and can maintain stability when repeatedly displaying or storing display information. Here, as the force applied to the particles constituting the display medium, in addition to the force attracted by the Coulomb force between the particles, an electric image force with the electrode and the substrate, an intermolecular force, a liquid cross-linking force, gravity and the like can be considered.

  An example of an information display panel using display medium particles manufactured according to the manufacturing method of the present invention will be described based on FIGS. 1 (a), (b) to 3 (a), (b).

  In the example shown in FIGS. 1 (a) and 1 (b), at least two or more types of display media 3 (here, white display consisting of a group of particles) having at least two or more types of optical reflectance and charging characteristics composed of at least one type of particles. The black display medium 3B including the medium 3W and the particle group is moved vertically to the substrates 1 and 2 according to the electric field applied from the outside of the substrates 1 and 2, and the black display medium 3B is visually recognized by the observer. The white display is performed, or the white display medium 3W is visually recognized by the observer. In the example shown in FIG. 1B, in addition to the example shown in FIG. 1A, for example, a partition 4 is provided between the substrates 1 and 2 to form a display cell. In addition, in FIG. 1B, the partition in front is omitted.

  In the example shown in FIGS. 2 (a) and 2 (b), at least two or more kinds of display media 3 (here, a white display made of particles) composed of at least one kind of particles and having different optical reflectance and charging characteristics. The substrate 1 corresponds to an 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. 2, the black display medium 3 </ b> B is visually recognized by the observer and black display is performed, or the white display medium 3 </ b> W is visually recognized by the observer and white display is performed. In the example shown in FIG. 2B, in addition to the example shown in FIG. 2A, partition walls 4 are provided, for example, in a lattice shape between the substrates 1 and 2 to form display cells. Further, in FIG. 2 (b), the front partition is omitted.

  In the example shown in FIGS. 3A and 3B, a display medium 3 (here, a white display made up of a group of particles) having at least one type of optical reflectance and charging characteristics composed of at least one type of particles. The medium 3W) is moved in a direction parallel to the substrates 1 and 2 in accordance with the electric field generated by applying a voltage between the electrode 5 and the electrode 6 provided on the substrate 1, and the white display medium 3W is moved. The observer visually recognizes the white display, or the observer visually recognizes the color of the electrode 6 or the substrate 1 to display the color of the electrode 6 or the substrate 1. In the example shown in FIG. 3B, in addition to the example shown in FIG. 3A, for example, a grid-like partition wall 4 is provided between the substrates 1 and 2 to form a display cell. Moreover, in FIG.3 (b), the partition in front is abbreviate | omitted.

  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.

  As a method for producing the display medium particles constituting the display medium used in the information display panel described above, the present invention is directed to directly forming a metal compound on the particle surface by sputtering, which can improve the fluidity of the display medium 3. There are features. Sputtering can obtain a very good adhesive force due to the high energy of the flying particles, and as a result, the durability which is a problem in the prior art can be improved.

  Examples of the metal compound include a metal oxide, a metal nitride, or a metal oxynitride. Examples of the metal oxide body surface include silicon oxide and titanium oxide. Also, the body surface of the metal oxynitride. Specific examples include silicon oxynitride and titanium oxynitride, but the present invention is not limited to this as long as the fluidity of the display medium 3 can be improved.

The form of sputtering on the particles is not particularly limited. For example, when a movable drum unit in which particles enter inside is installed between two facing sputtering targets and the drum unit is rotated, the particles fall from the upper part to the lower part of the drum unit. The method of carrying out sputtering processing from both sides can be taken. When forming a silicon compound, as the sputtering target _SiO 2, Si (boron or phosphorus-doped), such as SiC (nitrogen-doped) can be used. In order to form a titanium compound, TiO ₂ , Ti, TiO _x and the like can be targeted, but this is not the only case. The sputtering method is not particularly limited, and DC (direct current) sputtering, RF (high frequency) sputtering, AC (alternating current) sputtering, or the like can be used.

  FIG. 4 is a diagram showing a configuration of an example of a sputtering apparatus used in the present invention. In the example shown in FIG. 4, 11 is a movable drum unit that internally stores a particle group to be processed, 12 is a sputtering target, 13 is a driving device for rotating the movable drum unit 11, and 14 is a drum opening. The target is sputtered by the plasma generated on the entire surface of the target 12 (plasma is similarly generated from the other sputtering target not shown), and this is irradiated to the particle group set on the movable drum unit 11 to thereby form the present invention. Can be achieved.

  FIGS. 5A and 5B are partial cross-sectional views each showing an example of a movable drum unit. As shown in FIGS. 5A and 5B, the white particle group 15W and / or the black particle group 15B are set inside the movable drum unit 11, and the movable drum unit 11 is rotated (excited while rotating). The particle group moves from the upper part of the drum to the lower part. At that time, sputtering is performed from both sides while the particle group passes through the drum opening 14. Here, FIG. 5A shows an example in which one color particle group (here, black particle group 15B) is sputtered, and FIG. 5B shows two color particle groups (here, black particle group 15B and white particle group 15B). An example in which the particle group 15W) is sputtered simultaneously is shown. In any case, the display medium of the present invention can be suitably obtained as will be apparent from the examples described later.

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

  As for the substrate, at least one substrate is the transparent substrate 2 from which the color of the display medium 3 can be confirmed from the outside of the panel, and a material having high visible light transmittance and good heat resistance is preferable. The substrate 1 may be transparent or opaque. Examples of substrate materials include polymer sheets such as polyethylene terephthalate, polyethersulfone, polyethylene, polycarbonate, polyimide, and acrylic, flexible materials such as metal sheets, and flexible materials such as glass and quartz. There are no inorganic sheets. The thickness of the substrate is preferably 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 providing electrodes on information display panels include metals such as aluminum, silver, nickel, copper, and gold, and conductive metal oxides such as ITO, indium oxide, conductive tin oxide, and conductive zinc oxide. , Conductive polymers such as polyaniline, polypyrrole, polythiophene, etc. are exemplified and used as appropriate. As a method for forming an electrode, a method of forming the above-described materials into a thin film by sputtering, vacuum deposition, CVD (chemical vapor deposition), coating, or the like, or mixing a conductive agent with a solvent or a synthetic resin binder. The method of apply | coating is used. The electrode provided on the viewing side (display side) substrate needs to be transparent, but the electrode provided on the back side substrate does not need to be transparent. In any case, the above-mentioned material that is conductive and capable of pattern formation can be suitably used. Note that the electrode thickness is not particularly limited as long as the conductivity can be secured and the light transmittance is not hindered, and is preferably 3 to 1000 nm, preferably 5 to 400 nm. The material and thickness of the electrode provided on the back side substrate are the same as those of the electrode provided on the display side substrate described above, but need not be transparent. In this case, the external voltage input may be superimposed with direct current or alternating current.

  The partition 4 provided on the substrate as needed is optimally set according to the type of display medium involved in the display and is not limited in general, but the width of the partition is 2 to 100 μm, preferably 3 to 50 μm. The height of the partition wall is adjusted to 10 to 500 μm, preferably 10 to 200 μm. As shown in FIG. 6, the display cell formed by the partition walls made of these ribs is 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. The shape and the mesh shape are exemplified. It is better to make the portion corresponding to the cross section of the partition wall visible from the display side (the area of the frame portion of the display cell) as small as possible, and the display becomes clearer.

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

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

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

In the information display panel of the present invention, a powder fluid that exhibits high fluidity in an aerosol state in which solid particles are stably suspended as a dispersoid in a gas, for example, as a display medium between transparent substrates at least one of which is transparent. Such powder fluid can be easily and stably moved by a Coulomb force by applying a low voltage.
As described above, for example, the powder fluid used as the display medium in the present invention is a substance in the intermediate state between the fluid and particles that exhibits fluidity by itself without borrowing the force of gas or liquid. It is. This powder fluid can be in an aerosol state in particular, and in the information display panel of the present invention, a solid substance is used in a state of relatively stably floating as a dispersoid in the gas.

Next, the display medium particles (hereinafter also referred to as particles) of the present invention constituting the display medium in the information display panel 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 particular, acrylic urethane resin, acrylic silicone resin, acrylic fluororesin, acrylic urethane silicone resin, acrylic urethane fluororesin, fluororesin, and silicone resin are suitable from the viewpoint of controlling the adhesive force with the substrate.

  The charge control agent is not particularly limited. Examples of the negative charge control agent include salicylic acid metal complexes, metal-containing azo dyes, metal-containing oil-soluble dyes (including metal ions and metal atoms), and quaternary ammonium salt systems. Examples thereof include compounds, calixarene compounds, boron-containing compounds (benzyl acid boron complexes), and nitroimidazole derivatives. Examples of the positive charge control agent include nigrosine dyes, triphenylmethane compounds, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives, and the like. In addition, metal oxides such as ultrafine silica, ultrafine titanium oxide, ultrafine alumina, nitrogen-containing cyclic compounds such as pyridine and derivatives and salts thereof, various organic pigments, resins containing fluorine, chlorine, nitrogen, etc. are also charged. It can also be used as a control agent.

  As the colorant, various organic or inorganic pigments and dyes as exemplified below can be used.

Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon and the like.
Examples of blue colorants include C.I. I. Pigment blue 15: 3, C.I. I. Pigment Blue 15, Bituminous Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Metal-free Phthalocyanine Blue, Phthalocyanine Blue Partial Chlorides, Fast Sky Blue, Indanthrene Blue BC, and the like.
Examples of red colorants include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, risor red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, Alizarin Lake, Brilliant Carmine 3B, C.I. I. Pigment Red 2 etc.

Yellow colorants include chrome yellow, zinc yellow, cadmium yellow, yellow iron oxide, mineral first yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, C.I. I. Pigment Yellow 12 etc.
Examples of green colorants include chrome green, chromium oxide, pigment green B, C.I. I. Pigment Green 7, Malachite Green Lake, Final Yellow Green G, etc.
Examples of the orange colorant include red chrome yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. I. Pigment Orange 31 etc.
Examples of purple colorants include manganese purple, first violet B, and methyl violet lake.
Examples of white colorants include zinc white, titanium oxide, antimony white, and zinc sulfide.

  Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white. Examples of various dyes such as basic, acidic, disperse, and direct dyes include nigrosine, methylene blue, rose bengal, quinoline yellow, and ultramarine blue.

Examples of inorganic additives include titanium oxide, zinc white, zinc sulfide, antimony oxide, calcium carbonate, lead white, talc, silica, calcium silicate, alumina white, cadmium yellow, cadmium red, cadmium orange, titanium yellow, Examples include bitumen, ultramarine blue, cobalt blue, cobalt green, cobalt violet, iron oxide, carbon black, manganese ferrite black, cobalt ferrite black, copper powder, and aluminum powder.
These pigments and inorganic additives can be used alone or in combination. Of these, carbon black is particularly preferable as the black pigment, and titanium oxide is preferable as the white pigment.

  Further, the particles of the present invention preferably have an average particle diameter d (0.5) in the range of 0.1 to 20 μm, and are uniform and uniform. If the average particle diameter d (0.5) is larger than this range, the display is not clear, and if it is smaller than this range, the cohesive force between the particles becomes too large, which hinders the movement of the particles.

Furthermore, in the present invention, regarding the particle size distribution of each particle, the particle size distribution Span represented by the following formula is set to less than 5, preferably less than 3.
Span = (d (0.9) −d (0.1)) / d (0.5)
(However, d (0.5) is a numerical value indicating the particle diameter in μm that 50% of the particles are larger than this, and 50% is smaller than this, and d (0.1) is a particle in which the ratio of the smaller particles is 10%. (Numerical value expressed in μm, and d (0.9) is a numerical value expressed in μm for a particle size of 90% or less.)
By keeping Span within a range of 5 or less, the size of each particle is uniform and uniform particle movement is possible.

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

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

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

  As a result of intensive studies, the present inventors evaluated the range of the appropriate charging characteristic value of the particles used in the display medium by measuring the charge amount of the particles used in the display medium using the same carrier particles in the blow-off method. I found out that I can do it.

Furthermore, when applying a display medium such as a particle group or powdered fluid composed of the display medium particles of the present invention to a dry information display panel, it is important to manage the gas in the voids surrounding the display medium between the substrates. Yes, contributing to improved display stability. Specifically, it is important that the relative humidity at 25 ° C. is 60% RH or less, preferably 50% RH or less, more preferably 35% RH or less with respect to the humidity of the gas in the gap.
1A, 1B, 3A, and 3B, the gap portion is defined by the electrodes 5 and 6 and the display medium (particle group) from the portion sandwiched between the opposing substrate 1 and substrate 2. Alternatively, a gas portion in contact with a so-called display medium excluding an occupied portion of powder fluid 3, an occupied portion of partition 4 (when a partition is provided), and a seal portion of an information display panel is meant.
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.
When a particle group or powder fluid is used for the display medium, the volume occupation ratio of the display medium in the space between the opposing substrates is preferably 5 to 70%, more preferably 5 to 60%. When it exceeds 70%, the movement of the display medium is hindered, and when it is less than 5%, the contrast tends to be unclear.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples of the present invention and comparative examples, but the present invention is not limited to the following. In addition, the information display panel of an Example and a comparative example evaluated what produced by the following method according to the following reference | standard.

"Preparation of particles"
In Examples and Comparative Examples, black and white two-color particle groups (particle group A and particle group B) having different charging characteristics were used as particles.
Particle group A consists of acrylic urethane resin EAU53B (manufactured by Asia Industry Co., Ltd.) / IPDI crosslinking agent Excel Hardener HX (manufactured by Asia Industry Co., Ltd.), 4 parts by weight of carbon black (MA100 Mitsubishi Chemical Corporation), charge control. 2 parts by weight of the agent Bontron N07 (Orient Chemical Co., Ltd.) was added, kneaded, pulverized with a jet mill, and mechanical impact force was applied using a hybridizer device (Nara Machinery Co., Ltd.). In addition, classification was made after making it approximately spherical. The produced particle group A was an approximately spherical and negatively charged black particle group having an average particle diameter of 9.1 μm.
Particle group B was prepared by dissolving 0.5 parts by weight of AIBN (azobisisobutyronitrile) in 80 parts by weight of tertiary butyl methacrylate monomer and 20 parts by weight of 2- (diethylamino) ethyl methacrylate. A solution obtained by dispersing 20 parts by weight of titanium oxide, which has been made lipophilic by treatment with an agent, is suspended and polymerized in a 10-fold amount of a 0.5% aqueous surfactant (sodium lauryl sulfate) solution, filtered and dried. Then, it was prepared using a classifier (MDS-2: Nippon Numatic Industries). The produced particle group B was a positively charged spherical white particle having an average particle diameter of 8.5 μm.

“Preparation of particles for display media as display media of Examples and Comparative Examples”
<Example 1>
SiC was set as a target in a magnetron DC sputtering apparatus having two facing cathodes, a movable drum unit was installed between the two targets, and the prepared white particle group was set inside thereof. After exhausting to 5 × 10 ⁻⁴ Pa with a turbo molecular pump, Ar gas was introduced as a mixed gas at a flow rate of 30 sccm and O ₂ gas was adjusted to 0.5 Pa. While rotating the drum unit, power of 200 W was applied to each SiC target, and silicon oxide was formed on the white particle group by sputtering for 5 minutes. The black particles were also treated in the same manner as the white particles, and silicon oxide was formed on the black particles by sputtering.
<Example 2>
In the same manner as in Example 1, except that the white particle group and the black particle group were simultaneously set on the movable drum unit, and silicon oxide was simultaneously formed on the white particle group and the black particle group by sputtering. Obtained.

<Comparative Example 1>
Using a Henschel mixer, the fluidity modifier A (silica H2000 / 4, manufactured by Wacker) and the fluidity modifier B (silica SS20, manufactured by Nippon Silica) are added to the prepared white particle group and stirred and mixed. The fluidity modifier was adhered to the particle surface. The black particle group was treated in the same manner as the white particle group, and a fluidity modifier was adhered to the particle surface.
<Comparative example 2>
A display medium particle is prepared in the same manner as in Comparative Example 1 except that the white particle group and the black particle group are simultaneously charged into a Henschel mixer and two types of fluidity modifiers A and B are adhered simultaneously. However, the white particle group and the black particle group having different charging characteristics are aggregated, and the fluidity modifier cannot be applied to each particle.

<Durability test>
An information display panel is prepared by encapsulating a white display medium composed of a particle group and a black display medium composed of a particle group prepared in Example 1, Example 2, and Comparative Example 1 between two glass substrates each having an ITO electrode. Was made. The mixing ratio of the white display medium and the black display medium was set to the same volume amount, and the filling amount of the display medium between the substrates was adjusted to 60% by volume. Table 1 below shows the contrast measurement results and pass / fail results based on the produced information display panel. The pass / fail judgment was performed by applying a voltage of ± 150 V between the ITO electrodes provided on the two glass substrates to repeat display rewriting by reversing the black and white display medium and obtaining the contrast. And the thing with the ratio with respect to the initial contrast after 1 million times rewriting of 50% or more was set as the pass ((circle)), and the thing below 50% was set as the disqualification (x). The results are shown in Table 1 below. The contrast was measured using a reflection image densitometer (manufactured by Douglas Macbeth Co., Ltd.) for the optical density after initial and black and white rewrite display was repeated 1 million times. Here, the contrast is a reflection density during black display with respect to white display (contrast = reflection density during black display / reflection density during white display).

  From the results shown in Table 1, Examples 1 and 2 of the present invention can maintain good contrast even after the black and white display rewrite is repeated 1 million times as compared with Comparative Example 1, and are obtained according to the manufacturing method of the present invention. It can be seen that the information display panel using the display medium composed of the display medium particles has good repeated display rewriting durability.

  The information display panel using the particles for display media of the present invention includes display units of mobile devices such as notebook computers, PDAs, mobile phones, handy terminals, electronic papers such as electronic books and electronic newspapers, signboards, posters, and blackboards. Billboards, calculators, home appliances, car supplies, card displays such as point cards, IC cards, electronic advertisements, electronic POPs, electronic price tags, electronic shelf labels, electronic musical scores, RF-ID device displays, etc. Is preferably used.

(A), (b) is a figure which shows an example of the information display panel of this invention, respectively. (A), (b) is a figure which shows the other example of the information display panel of this invention, respectively. (A), (b) is a figure which shows the further another example of the information display panel of this invention, respectively. It is a figure which shows the structure of an example of the sputtering device used by this invention. (A), (b) is a figure which shows the structure of an example of a movable drum unit in a partial cross section, respectively. 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

DESCRIPTION OF SYMBOLS 1, 2 Substrate 3 Display medium 3W White display medium 3B Black display medium 4 Bulkhead 5, 6 Electrode 11 Movable drum unit 12 Sputtering target 13 Drive device 14 Drum opening 15W White particle group 15B Black particle group

Claims (7)

  A display medium used for an information display panel that displays information such as an image by moving the display medium by enclosing the display medium between two opposing substrates at least one of which is transparent and applying an electric field to the display medium A method for producing particles for a display medium, wherein a metal compound is formed on a particle surface by a sputtering method.   When producing a plurality of types of display medium particles constituting a plurality of types of display media enclosed in the same information display panel, a metal compound is simultaneously applied to the surfaces of the plurality of types of display medium particles constituting the plurality of types of display media. It forms by sputtering method, The manufacturing method of the particle | grains for display media of Claim 1 characterized by the above-mentioned.   The method for producing particles for a display medium according to claim 1 or 2, wherein the metal compound is a metal oxide, a metal nitride, or a metal oxynitride.   4. The method for producing particles for a display medium according to claim 3, wherein the metal oxide is mainly composed of silicon oxide or titanium oxide.   4. The method for producing particles for a display medium according to claim 3, wherein the metal oxynitride mainly comprises silicon oxynitride or titanium oxynitride.   A particle for a display medium, which is obtained by producing according to the production method according to claim 1.   An information display panel, wherein the display medium particles according to claim 6 are used as a particle group or a powder fluid.

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