JP2006313337A - Particle for black display medium and information display panel using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide particles for a black display medium having a high blackness degree and irregularity firmly fixed to particle surfaces, and to provide an information display panel that can eliminate display failure or decrease in contrast by using the particles. <P>SOLUTION: The particles for a display medium for displaying information by moving a display medium sealed between two substrates under an electric field are approximately spherical particles produced by polymerizing a source material of particles containing monomers, and characterized in that: the source material of particles contains an acrylic and methacrylic resin-hydrocarbon resin copolymer or a copolymer of an acrylic and methacrylic resin and an acrylic and methacrylic resin having a hydrocarbon group or a fluorohydrocarbon group in a side chain; a part of the monomers or the entire monomers are polyfunctional monomers having a plurality of polymerization reactive groups in one molecule; the particle has minute irregularity uniformly distributed on the particle surface; the particles contain carbon black having a primary particle diameter of 30 nm or less and a DBP absorption of 120 cm<SP>3</SP>/100 g or less, by 4 parts by weight or more with respect to the resin constituting the particles and contain a charge controlling agent by 60% or less of the amount of the carbon black. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a display medium used for an information display panel for displaying information by moving a display medium by enclosing the display medium between two substrates transparent at least one and applying an electric field to the display medium. The present invention relates to a black display medium particle and an information display panel using the same.

  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, a display medium is sealed between two substrates, at least one of which is transparent, and an electric field is applied to the display medium, thereby moving the display medium to display information. An information display panel is known.
趙 Kuniori and three others, “New Toner Display Device (I)”, July 21, 1999, Annual Meeting of the Imaging Society of Japan (83 times in total) “Japan Hardcopy'99” Proceedings, p.249-252

  In the information display panel of the type that moves the display medium described above, the particle diameter of the display medium particles (hereinafter also referred to as particles) constituting the display medium by an electric field is 0.5. About 50 μm is preferable. If it is too small, the physical adhesion between the particles and between the particles and the substrate will increase, and a large electric field will be required for movement. If it is too large, the distance between the substrates will have to be large. Is required. However, even if the particle diameter is within the above range, when the surface smooth particle is used in the above-described information display panel, it is applied to the substrate to generate an electric field necessary for moving (driving) the particle. There was a problem that the voltage increased. If this is a smooth surface, the physical adhesion between the particles and between the particles and the substrate will increase, and the energy required to move them through the space between the substrates will be increased. It is because it ends up.

  As a method for solving this problem, the most easily performed method is a method in which metal oxide fine particles or the like (external additive) are attached to the particle surface to make the particle surface uneven, thereby reducing the adhesion force. When this method is used for the display medium particles used in the information display panel described above, the transition of the external additive generated between the particles and between the particles and the substrate, and the external additive added to the particle surface and the substrate surface. There has been a problem that display defects occur due to the influence of fixing or the like. In addition, there is a method in which a reaction-inactive solvent or the like is added to the particle raw material to be polymerized to polymerize, and then the solvent is removed by heating or extraction to produce porous particles, thereby making the surface uneven. In addition, a process and equipment for removing the solvent and the like are required, which is not efficient.

  In addition, when producing the black display medium particles as the above-described surface uneven particles, it is not possible to obtain black display medium particles having high blackness depending on the configuration of the carbon black and the amount of the charge control agent added. It was.

  The object of the present invention is to eliminate the above-mentioned problems, and to obtain high blackness black display medium particles capable of obtaining irregularities firmly fixed on the particle surface, and to reduce display defects and contrast ratios using the particles. An information display panel that can be solved is to be provided.

The black display medium particle of the present invention is for information display in which a display medium is sealed between two substrates, at least one of which is transparent, and an electric field is applied to the display medium to move the display medium to display information. In the display medium particles constituting the display medium used for the panel, (1) the particles are roughly spherical particles obtained by polymerizing a particle raw material containing a monomer, and (acrylic and methacrylic) resin-carbonized in the particle raw material A copolymer of a hydrogen-based resin copolymer or (acrylic and methacrylic) resin- (acrylic and methacrylic resin having a hydrocarbon or fluorinated hydrocarbon in the side chain), and a part or all of the monomer is 1 It is a polyfunctional monomer having a plurality of polymerization reactive groups in the molecule, and has uniform unevenness on the particle surface, and (2) The configuration resins, with the primary particle diameter contains 30 (nm) DBP absorption amount of less ¹²⁰ (cm 3 / 100g) the at which carbon black than 4 parts by weight or more, the amount of carbon black a charge control agent It is characterized by containing 60% or less.

  In addition, as a suitable example of the particle | grains for black display media of this invention, it contains 10 weight part or less of the said carbon black with respect to particle | grain constituent resin, and contains 0.1% or more of the amount of carbon black of a charge control agent. The minute unevenness is a convex or concave portion having an equivalent diameter of 0.01 to 0.5 μm, and the (resin and methacrylic) resin-hydrocarbon resin copolymer hydrocarbon resin is a styrene resin. And the particle diameter of the particles is 0.5 to 50 μm. A more preferable range of minute irregularities is a diameter equivalent diameter of 0.05 to 0.35 μm.

  The information display panel of the present invention is an information display for displaying information by moving a display medium by enclosing the display medium between two substrates, at least one of which is transparent, and applying an electric field to the display medium. The display panel is characterized in that the black display medium particles having the above-described configuration are used alone or together with display medium particles of other colors.

According to the particles for display media of the present invention, (1) (acrylic and methacrylic) resin-hydrocarbon resin copolymer or (acrylic and methacrylic) resin- (hydrocarbon or fluorocarbon in the side chain) is contained in the particle raw material. Acrylic and methacrylic (having hydrocarbons) resins are included, and some or all of these monomers are polyfunctional monomers with multiple polymerization reactive groups in one molecule, so they are firmly attached to the particle surface. Fixed irregularities can be obtained. Further, (2) in the component ratio of particles, with respect to particle configuration resins, primary particle size of 30 (nm) DBP absorption amount of less ¹²⁰ (cm 3 / 100g) 4 parts by weight or more in a carbon black or less In addition, since the charge control agent is contained in an amount of 60% or less of the amount of carbon black, particles for black display media with high blackness can be obtained. Therefore, according to the information display panel using the black display medium particles of the present invention as a display medium, there is no decrease in display contrast and response speed even when rewriting display information repeatedly, and durability in display performance is improved. A good information display panel can be obtained.

  First, a basic configuration of an information display panel using the black display medium particles (hereinafter, also referred to as particles) of the present invention as a display medium will be described. In the information display panel which is an object of the present invention, an electric field is applied to a display medium sealed between two opposing substrates. In accordance with the applied electric field direction, the charged display medium is attracted by the force of the electric field or Coulomb force, and the moving direction of the display medium is switched by the change in the electric field direction, whereby information such as an image is displayed. Therefore, it is necessary to design the information display panel so that the display medium can move uniformly and maintain stability when the displayed information is rewritten or when the displayed information is continuously displayed. Here, as the force applied to the particles constituting the display medium, in addition to the force attracting each other by the Coulomb force between the particles, the electric mirror image force between the electrode and the substrate, the intermolecular force, the liquid cross-linking force, gravity and the like can be considered.

  An example of an information display panel that is an object of the present invention will be described with reference to FIGS. 1 (a) and (b) to FIGS. 3 (a) and 3 (b). In the following example, a black display medium using the particles for black display medium of the present invention is used as the black display medium, and the same white display medium can be used.

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

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

In the example shown in FIGS. 3A and 3B, at least one type of display medium 3 (here, black display medium particles) having at least an optical reflectance and a charging property composed of at least one type of particles. In the direction parallel to the substrates 1 and 2 depending on the electric field generated by applying a voltage between the electrode 5 and the electrode 6 provided on the substrate 1. The black display medium 3W is visually recognized by the observer and black display is performed, or the color of the electrode 6 or the substrate 1 is visually recognized by the observer and the color of the electrode 6 or the substrate 1 is displayed. Yes. 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 cell. Moreover, in FIG.3 (b), the partition in front is abbreviate | omitted.
The electrode may be provided outside the substrate or may be provided so as to be embedded inside the substrate.

The features of the present invention are (1) roughly spherical particles obtained by polymerizing a particle raw material containing a monomer as a display medium particle, and (acrylic and methacrylic) resin-hydrocarbon type in the particle raw material. Resin copolymer or (acrylic and methacrylic) resin- (copolymer of (acrylic and methacrylic) having a hydrocarbon or fluorinated hydrocarbon in the side chain) resin and a part or all of the monomer in one molecule A polyfunctional monomer having a plurality of polymerization reactive groups, and using particles having uniformly fine irregularities on the particle surface, and (2) in the composition ratio of the particles, with the following particle size containing 30 (nm) DBP absorption amount of less ¹²⁰ (cm 3 / 100g) the at which carbon black than 4 parts by weight or more, the carbon a charge control agent That it contains less than 60% of the amount of the rack, in.

  By configuring as in the above (1), fixed irregularities without dropping off are formed at the time of polymerization without steps such as volatilization or extraction of solvents, etc., so that the electric field necessary for driving the display medium is reduced. Particles that are low and hardly cause display defects can be stably produced. Regarding the size of the surface irregularities, the convex portion or the concave portion is preferably in the range of 0.01 to 0.5 μm in diameter equivalent diameter. A more preferable range is 0.05 to 0.35 μm. If the surface unevenness is too small, a sufficient adhesion reducing effect cannot be obtained, and if the surface unevenness is too large, the surface of the uneven portion itself adheres and the effect of unevenness is lost.

  Here, when the amount of the polyfunctional monomer having a plurality of polymerization reactive groups in one molecule is less than 15 mol%, the particle surface unevenness does not appear, or the unevenness becomes small and the effect is small. . Further, when the total amount is a polyfunctional monomer, the structure of the resin constituting the particles is strengthened, particles having excellent heat resistance and excellent display durability for rewriting repeated display can be obtained. In addition, it is more preferable that the polyfunctional monomer having a plurality of polymerization reactive groups in one molecule is an acrylic or methacrylic monomer because irregularities on the particle surface are easily produced.

  As the polymerization method, a suspension polymerization method is preferably used, and a nonionic surfactant having a polyoxyethylene chain is preferable as a material used as a suspension stabilizer in the suspension polymerization. It has a relatively good suspension stability and has little residue on the particle surface, and has little influence on the charging performance of the produced particles. Furthermore, it is more desirable to use a surfactant having a surfactant effect of both the polyoxyethylene chain and the sulfonate nonion and anion as the suspension stabilizer. Suspension stability is higher than in the case of only polyoxyethylene chains. Moreover, the method of using water-soluble resins, such as PVA and a cellulose resin, can also be taken as a suspension stabilizer. In this case, the suspension stability is very high, but there is also a problem that the suspension stabilizer remains on the particle surface and affects the chargeability of the particle.

  There is also a method of using a powder composed of inorganic fine particles of 10 to 1000 nm as a suspension stabilizer. This method is a method in which an inorganic oxide dissolved under acidity is returned to neutrality and precipitated as fine particles and used as a stabilizer. After the polymerization is completed, the inorganic oxide is dissolved again and removed from the particle surface. This method also exhibits very good suspension stability. However, there is a drawback that a system such as treatment of acidic waste liquid is required. As the polymerization initiator, it is optimal to use a substance having a 10-hour half-life temperature of 40 to 75 ° C. If the temperature is too low, polymerization proceeds even at room temperature, making it difficult to produce a good suspension. Further, when the viscosity of the particle raw material is excessively increased by polymerization, the droplets due to the surface tension are not spheroidized, and almost spherical particles cannot be obtained. On the other hand, if the temperature is too high, the polymerization takes too much time and is not efficient. As a polymerization initiator, when it dissolves in a suspension such as water, emulsion polymerization proceeds, and a large amount of fine particles that are not colored are produced. If this is used as a particle for a display medium, the display quality is lowered. In order to prevent this problem, it is desirable to use an oil-soluble substance. Among the initiators, acyl peroxides may be mentioned, or azo initiators having 10 or more carbon atoms in the molecule are applicable.

  The (acrylic and methacrylic) resin-hydrocarbon resin copolymer is more preferably an (acrylic and methacrylic) resin-hydrocarbon resin block copolymer. This is because each resin is in the form of a block, which makes it easier to express the characteristics than the random structure, and the particle surface can be efficiently roughened. In addition, since the hydrocarbon resin of the (acrylic and methacrylic) resin-hydrocarbon resin copolymer is a styrene resin, a difference in compatibility with the (acrylic and methacrylic) resin is likely to occur, and the particle surface Can be efficiently formed. About a coloring agent, in order to prevent that the efficiency of coloring by transfer to the suspension medium at the time of suspension deteriorates, it is necessary to hydrophobize by surface treatment. Moreover, the resin coating of the colorant by masterbatch production is also effective.

  When the display medium particles contain a charge control agent in order to obtain chargeability, a clear charge performance can be obtained and the desired performance can be easily obtained. The target charging performance includes charge amount, charging uniformity, reverse charging prevention, and the like. As a charge control agent, there is a method in which a poorly soluble substance is dispersed and contained in a monomer as a particle raw material. This method actively creates a non-uniform charge distribution, and simultaneously generates trigger particles that are easy to drive even with a small electric field. This is an effective method for manufacturing. There is also a method using a monomer-soluble charge control agent. This method is advantageous in terms of uniform dispersion of the charge control agent, enables particles to move at the same potential with uniform chargeability, and facilitates obtaining good display quality.

  There is also a method in which a copolymerizable monomer having a chargeable functional group in the molecule is blended in the particle raw material and used as a charge control agent that is copolymerized during polymerization and chemically immobilized in the resin. This method can localize the chargeable site by orienting the chargeable functional group on the particle surface, and has the advantage that the effect can be obtained with a small amount, and the charge control agent bleed-out and dropping off. This is effective in ensuring the durability of the chargeability of the particles in that it hardly occurs.

  The black display medium particles preferably have a heat resistance of 60 ° C. or higher in terms of the usage environment in the information display panel. However, the heat resistance necessary for ensuring the physical heat resistance and sufficient charge amount is provided. In consideration, the Tg of the resin is preferably 60 ° C. or higher. In addition, when particles are obtained by polymerizing a particle raw material having a larger proportion of monomers having a plurality of polymerizable functional groups in the molecule, good heat resistance can be obtained, but in this case, Tg is not observed.

  FIG. 4 shows an example in which the black display medium particles of the present invention are imaged with a scanning electron microscope (SEM). The example of FIG. 4 shows a state where the particle surface is enlarged at an enlargement rate of 3000 times on the left side and an enlargement rate of 15000 times on the right side, and fine irregularities on the order of several tens of nanometers are formed on the particle surface. I can see the situation.

In the present invention, the above (2) as shown in, the component ratio of particles, with respect to particle configuration resins, primary particle size of 30 (nm) DBP absorption amount of less ¹²⁰ (cm 3/100 g) In addition to containing 4 parts by weight or more of the following carbon black, the charge control agent is configured to contain 60% or less of the amount of carbon black. By configuring in this way, it is possible to obtain black display medium particles having high black that can solve the problem of insufficient blackness, and by configuring an information display panel using the display medium particles, Contrast display can be obtained.

Here, the reason why the primary particle diameter of carbon black is limited to 30 nm or less is that when it exceeds 30 nm, the blackness (colorability) becomes small. To limit the DBP absorption of carbon black and ¹²⁰ (cm 3 / 100g) or less, exceeds ¹²⁰ (cm 3 / 100g), an insulating property is insufficient, because the part charge leak. Furthermore, the reason why the amount of carbon black added is limited to 4 parts by weight or more with respect to the particle-constituting resin is that if it is less than 4 parts by weight, the colorability is insufficient. Furthermore, the content of the charge control agent with respect to the amount of carbon black is limited to 60% or less. If the content exceeds 60%, poor polymerization occurs and particles cannot be produced, or even if possible, this black display medium. This is because, in an information display panel using the particles for black as a black display medium, a drive failure occurs, resulting in a low contrast display.

  In the present invention, the DBP absorption amount is a measurement method generally used for grasping the carbon structure. From the amount of DBP (Dibutyl phthalate) required to fill the voids of the deposited carbon black, The unit is expressed in ml / 100 g. The higher this value, the higher the carbon structure, and the lower the carbon structure.

  Moreover, it is preferable to contain 10 parts by weight or less of carbon black with respect to the particle constituent resin. The reason is that when the carbon black with respect to the particle-constituting resin exceeds 10 parts by weight, polymerization failure occurs. Furthermore, it is preferable to contain a charge control agent in an amount of 0.1% or more of the amount of carbon black. The reason is that when the content of the charge control agent is less than 0.1% of the amount of carbon black, in the information display panel using the black display medium particles as a black display medium, a drive failure occurs, This is because the display becomes low contrast.

  Hereinafter, the basic structure of particles having irregularities on the surface thereof in the particles for black display medium (also simply referred to as particles) used in the information display panel of the present invention will be described.

  The particles are preferably spherical. The particles can contain a charge control agent, a colorant, an inorganic additive, and the like, if necessary, in the resin as the main component, as in the conventional case. Examples of resins, charge control agents, colorants, and other additives will be given below.

  The main component of the particle raw material of the present invention is (acrylic and methacrylic) resin-hydrocarbon resin copolymer or (acrylic and methacrylic) resin- (acrylic having side chain hydrocarbon or fluorohydrocarbon and Copolymers with (methacrylic) resins, but in addition, urethane resins, urea resins, acrylic resins, polyester resins, acrylic urethane resins, acrylic urethane silicone resins, acrylic urethane fluororesins, acrylic fluororesins, silicone resins, acrylic silicone resins , Epoxy resin, polystyrene resin, styrene acrylic resin, polyolefin resin, butyral resin, vinylidene chloride resin, melamine resin, phenol resin, fluorine resin, polycarbonate resin, polysulfone resin, polyether resin, polyamide resin And the like. In particular, a resin component such as an acrylic resin, an acrylic fluororesin, a polystyrene resin, or a styrene acrylic resin may be included from the viewpoint of controlling the adhesive force with the substrate and the ease of suspension polymerization.

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

  In the black display medium particles of the present invention, carbon black is used as the colorant.

  The particles used in the present invention have a particle size in the range of 0.5 to 50 μm, and the particle size is preferably uniform and uniform. If the particle diameter is larger than this range, the display is not clear. If the particle diameter is smaller than this range, the cohesive force between the particles becomes too large, which hinders movement as a display medium.

Furthermore, in the present invention, regarding the particle size distribution of the particles for each display medium, the particle size distribution Span represented by the following formula is less than 5, preferably less than 3.
Span = (d (0.9) −d (0.1)) / d (0.5)
(However, d (0.5) is a numerical value 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 movement as a uniform display medium becomes possible.

  Furthermore, regarding the correlation between the particles for each display medium, the ratio of d (0.5) of the particles having the minimum diameter to d (0.5) of the particles having the maximum diameter among the used particles is 50 or less, preferably 10 or less. It is important to do.

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

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

  As a result of intensive studies, the present inventors have been able to evaluate the range of proper charging characteristics of display medium particles by measuring the charge amount of the particles used in the display medium using the same carrier particles in the blow-off method. I found.

Furthermore, when a display medium composed of display medium particles is applied to a dry information display panel that is driven in an air space, it is important to manage the gas in the void surrounding the display medium between the substrates. Contributes to improved stability. Specifically, it is important that the relative humidity at 25 ° C. is 60% RH or less, preferably 50% RH or less, with respect to the gas humidity in the void portion.
1A, 1B, 3A, and 3B, the gaps are defined as electrodes 5 and 6 (electrodes on the inner side of the substrate). ), An occupied portion of the display medium 3, an occupied portion of the partition wall 4 (when a partition wall is provided), and a gas portion in contact with a so-called display medium, excluding a seal portion of the information display panel.
The gas in the gap is not limited as long as it is in the humidity region described above, but dry air, dry nitrogen, dry argon, dry helium, dry carbon dioxide, dry methane, and the like are preferable. This gas needs to be sealed in 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 that is the subject of the present invention is not limited as long as the display medium can be moved and the contrast can be maintained, but is usually adjusted to 10 to 500 μm, preferably 10 to 200 μm.
The volume occupation ratio of the display medium in the space between the opposing substrates is preferably 5 to 70%, more preferably 5 to 60%. If it exceeds 70%, the movement of the display medium is hindered, and if it is less than 5%, the contrast tends to be unclear.

  Hereinafter, each member which comprises the information display panel used as the object 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, polyethylene naphthalate, polyethersulfone, polyethylene, polycarbonate, polyimide, and acrylic, flexible materials such as metal sheets, and glass and quartz. An inorganic sheet having no flexibility is mentioned. The thickness of the substrate is preferably from 2 to 5000 μm, more preferably from 5 to 2000 μm. If it is too thin, it will be difficult to maintain the strength and the spacing uniformity between the substrates, and if it is thicker than 5000 μm, it will be a thin information display panel. Is inconvenient.

  As an electrode forming material for providing an electrode on an information display panel, metals such as aluminum, silver, nickel, copper, gold, indium tin oxide (ITO), indium oxide, conductive tin oxide, antimony tin oxide ( ATO), conductive metal oxides such as conductive zinc oxide, and conductive polymers such as polyaniline, polypyrrole, and polythiophene are exemplified and appropriately selected and used. As a method for forming an electrode, a method of forming the above-described materials into a thin film by sputtering, vacuum deposition, CVD (chemical vapor deposition), coating, or the like, or mixing a conductive agent with a solvent or a synthetic resin binder. The method of apply | coating is used. The electrode provided on the viewing side (display surface side) substrate needs to be transparent, but the electrode provided on the back side substrate does not need to be transparent. In any case, the above-mentioned material that is conductive and capable of pattern formation can be suitably used. Note that the electrode thickness is not particularly limited as long as the conductivity can be secured and the light transmittance is not hindered, and is preferably 3 to 1000 nm, preferably 5 to 400 nm. The material and thickness of the electrode provided on the back side substrate are the same as those of the electrode provided on the display side substrate described above, but need not be transparent. In this case, the external voltage input may be superimposed with direct current or alternating current.

  The partition 4 provided on the substrate as needed is optimally set according to the type of display medium involved in the display and is not limited in general, but the width of the partition is 2 to 100 μm, preferably 3 to 50 μm. The height of the partition wall is adjusted to 10 to 500 μm, preferably 10 to 200 μm. As shown in FIG. 5, the cells formed by the partition walls made of these ribs are exemplified by a square shape, a triangular shape, a line shape, a circular shape, and a hexagonal shape as viewed from the plane of the substrate. And a mesh shape. It is better to make the portion corresponding to the cross section of the partition wall visible from the display surface side (the area of the cell frame) as small as possible, and the display becomes clearer.

  EXAMPLES 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 the particle | grains produced with the following method in the space between panel substrates with the dry air of humidity 50% RH or less according to the following reference | standard. did.

<Example 1>
40 parts by weight of methyl methacrylate monomer (Kanto Chemical Reagent) as positively charged particles and 60 parts by weight of ethylene glycol dimethacrylate (Wako Pure Chemical Reagent) as a polyfunctional monomer having a plurality of polymerization reactive groups in one molecule are positively charged. As a monomer poorly soluble charge control agent, 1 part by weight of a nigrosine compound (Bontron N07: manufactured by Orient Chemical Co.) and as a black inorganic pigment-based colorant, carbon black having a primary particle diameter of 24 nm and a DBP absorption of 100 ml / g (MA100) ： Mitsubishi Chemical Co., Ltd.) 40 parts by weight of acrylic resin (Delpet 80NH: Asahi Kasei Chemicals Co., Ltd.) dispersed in 60 parts by weight in a master batch was dispersed by treating with a sand mill for 1 hour. And methacrylic resins)-(hydrocarbons or fluorocarbons in the side chain) Copolymers of acrylic and methacrylic) resin with (Modiper F600: NOF, fluorocarbon _component: C _{8 F} 17) were dissolved in 10 wt.

  Next, 2 parts by weight of azobisdimethylvaleronitrile (V-65: Wako Pure Chemical Industries, Ltd./10-hour half-life temperature 51 ° C.), which is an azo-based substance having 10 or more carbon atoms in one molecule, is dissolved in this mixed solution. The suspension was suspended in purified water to which 0.5 wt% of polyoxyethylene alkyl ether sodium sulfate (Latemul E-118B: manufactured by Kao) was added as a surfactant containing a polyoxyalkylene chain and a sulfonate in the molecule, After polymerization, filtration, and drying, black particles having an average particle size of 9.3 μm were obtained in a particle size range of 0.5 to 50 μm using a classifier (MDS-2: Nippon Pneumatic Industry). When the surface of the particles was observed with an SEM, irregularities having a diameter equivalent to 90 nm were confirmed.

Negatively charged particles include 60 parts by weight of styrene monomer (Kanto Chemical Reagent) and 40 parts by weight of divinylbenzene (DVB-960: manufactured by Nippon Steel Chemical Co., Ltd.) as a multifunctional monomer having a plurality of polymerization reactive groups in one molecule. In addition, 5 parts by weight of a phenol-based condensate (Bontron E89: manufactured by Orient Chemical Co., Ltd.) as a negatively charged monomer poorly soluble charge control agent, and 40% by weight of titanium oxide (Taipaque CR-50: manufactured by Ishihara Sangyo) as a white inorganic pigment-based colorant. Parts are dispersed by treating with a sand mill for 4 hours, and a copolymer of (acrylic and methacrylic) resin- (acrylic and methacrylic having a hydrocarbon or fluorinated hydrocarbon in the side chain) resin (Modiper F600: Japan) Fat and oil, carbon fluoride component: C ₈ F ₁₇ ) 8 weight was dissolved.

  Next, a solution obtained by dissolving 2 parts by weight of lauryl peroxide (Perroyl L: manufactured by NOF / 10-hour half-life temperature 61.6 ° C.) as an acyl peroxide in this solution is used as a surfactant as a polyoxy Suspended, polymerized, filtered, and dried in purified water to which 0.5 wt% of sodium ethylene alkyl ether sulfate (Latemul E-118B: manufactured by Kao) was added, a classifier (MDS-2: Nippon Pneumatic Industry) Used to obtain white particles having an average particle size of 10.1 μm in a particle size range of 0.5 to 50 μm. When the surface of the particles was observed with an SEM, irregularities having an equivalent diameter of 140 nm were confirmed.

  The mixed particles are filled in a cell having a glass substrate disposed on a side of 100 μm, one of which is treated with ITO on the inside and a copper substrate on the other side, so that the volume occupancy of the particles is 11%, An information display panel was obtained. When a power supply is connected to each of the ITO glass substrate and the copper substrate, and a direct current voltage of 250 V is applied so that the ITO glass substrate is at a low potential and the copper substrate is at a high potential, the positively charged particles are negatively charged on the low potential electrode side. The particles move to the high potential electrode side, the information display panel that is observed through the glass substrate is displayed in black, and then when the potential of the applied voltage is reversed, the particles move in the opposite direction and are observed. The information display panel was displayed in white. In any case, there was no mixture of particles desired to be displayed on the ITO glass substrate and different color particles, and good display quality was obtained. The contrast ratio (ratio of reflectance during white display and reflectance during black display) was measured with a Macbeth densitometer D19, and the contrast ratio was 9.5.

<Example 2>
In Example 1, two types of particles were prepared in the same procedure as in Example 1 except that carbon black (MA77: manufactured by Mitsubishi Chemical) having a primary particle diameter of 23 nm and a DBP absorption of 68 ml / g was used. A display panel was prepared and evaluated. At this time, the contrast ratio at a voltage of 250 V was 10.2.

<Example 3>
40 parts by weight of methyl methacrylate monomer (Kanto Chemical Reagent) as positively charged particles and 60 parts by weight of ethylene glycol dimethacrylate (Wako Pure Chemical Reagent) as a polyfunctional monomer having a plurality of polymerization reactive groups in one molecule are positively charged. Carbon black having a primary particle diameter of 24 nm and a DBP absorption of 100 ml / g as a black inorganic pigment-based colorant and 2.4 parts by weight of a nigrosine compound (Bontron N07: manufactured by Orient Chemical Co.) 10 parts by weight of a masterbatch in which 40 parts by weight (MA100: manufactured by Mitsubishi Chemical) was previously dispersed in 60 parts by weight of an acrylic resin (Delpet 80NH: manufactured by Asahi Kasei Chemicals) was dispersed by treating with a sand mill for 1 hour. Acrylic and methacrylic resins-(hydrocarbons or fluorocarbons in the side chain) Copolymers of acrylic and methacrylic) resin with hydrogen (Modiper F600: NOF, fluorocarbon _component: C _{8 F} 17) were dissolved in 10 wt.

  Next, 2 parts by weight of azobisdimethylvaleronitrile (V-65: Wako Pure Chemical Industries, Ltd./10-hour half-life temperature 51 ° C.), which is an azo-based substance having 10 or more carbon atoms in one molecule, is dissolved in this mixed solution. The suspension was suspended in purified water to which 0.5 wt% of polyoxyethylene alkyl ether sodium sulfate (Latemul E-118B: manufactured by Kao) was added as a surfactant containing a polyoxyalkylene chain and a sulfonate in the molecule, After polymerizing, filtering and drying, black particles having an average particle size of 9.3 μm were obtained in a particle size range of 0.5 to 50 μm using a classifier (MDS-2: Nippon Pneumatic Industry). When the surface of the particles was observed with an SEM, irregularities having a diameter equivalent to 90 nm were confirmed.

  As the negatively charged particles, the white particles of Example 1 were used.

  The above mixed particles are filled through a cell having a glass substrate disposed with a spacer of 100 μm, one with an inner ITO treatment and the other with a copper substrate, so that the volume occupancy of the particles is 11%. An information display panel was obtained. When a power supply is connected to each of the ITO glass substrate and the copper substrate, and a direct current voltage of 250 V is applied so that the ITO glass substrate is at a low potential and the copper substrate is at a high potential, the positively charged particles are negatively charged on the low potential electrode side. The particles move to the high potential electrode side, the information display panel that is observed through the glass substrate is displayed in black, and then when the potential of the applied voltage is reversed, the particles move in the opposite direction and are observed. The information display panel was displayed in white. In any case, there was no mixture of particles desired to be displayed on the ITO glass substrate and different color particles, and good display quality was obtained. The contrast ratio (ratio of reflectance during white display and reflectance during black display) was measured with a Macbeth densitometer D19, and the contrast ratio was 9.5.

<Example 4>
From the positively charged particles of Example 3, black particles having an average particle size of 9.5 μm were obtained using the same method as Example 3 except that 10 parts by weight of the master batch was changed to 25 parts by weight. When the surface of the particles was observed with an SEM, irregularities with an equivalent diameter of 150 nm were observed. Using the white particles of Example 1, the information display panel was similarly evaluated, and the contrast ratio was 8.9, which was good.

<Example 5>
From the positively charged particles of Example 3, 2.4 parts by weight of a nigrosine compound (Bontron N07: manufactured by Orient Chemical Co., Ltd.) was changed to 0.004 parts by weight of a monomer-soluble charge control agent (Acrybase FCA-201PS: manufactured by Fujikura Kasei). Using the same method as in Example 3, black particles having an average particle diameter of 9.8 μm were obtained. When the surface of this particle was observed with an SEM, irregularities with an equivalent diameter of 90 nm were observed. Using the white particles of Example 1, the information display panel was similarly evaluated. The contrast ratio was 9.0, which was good.

<Comparative Example 1>
In Example 1, two types of particles were prepared in the same manner as in Example 1 except that carbon black (# 20: manufactured by Mitsubishi Chemical) having a primary particle diameter of 50 nm and a DBP absorption amount of 121 ml / g was used. An information display panel was prepared and evaluated. At this time, the contrast ratio at a voltage of 250 V was 5.8.

<Comparative Example 2>
In Comparative Example 1, two types of particles were prepared by the same procedure as in Comparative Example 1 except that no charge control agent was added to the positively chargeable particles, and an information display panel was prepared and evaluated. At this time, the contrast ratio at a voltage of 250 V was 1.3.

<Comparative Example 3>
In Example 1, two types of particles were prepared in the same procedure as in Example 1 except that carbon black (# 3050B: manufactured by Mitsubishi Chemical) having a primary particle diameter of 50 nm and a DBP absorption of 175 ml / g was used. An information display panel was prepared and evaluated. At this time, the contrast ratio at a voltage of 250 V was 4.6.

<Comparative example 4>
From the positively charged particles of Example 3, black particles having an average particle diameter of 9.4 μm were obtained using the same method as Example 3 except that 10 parts by weight of the master batch was changed to 8 parts by weight. When the surface of the particles was observed with an SEM, irregularities having an equivalent diameter of 100 nm were observed. When the white display particles of Example 1 were similarly used to evaluate the information display panel, the contrast ratio was 4.5, which was insufficient.

<Comparative Example 5>
From the positively charged particles of Example 3, the same method as in Example 3 was used except that 10 parts by weight of the master batch was changed to 30 parts by weight. However, the particles were agglomerated at the stage of polymerization, and good particles were obtained. There wasn't.

<Comparative Example 6>
A black particle having an average particle diameter of 9.5 μm was used in the same manner as in Example 3 except that 2.4 parts by weight of the nigrosine compound (Bontron N07: manufactured by Orient Chemical Co., Ltd.) was changed to 3 parts by weight from the positively charged particles of Example 3. Particles were obtained. When the surface of the particles was observed with an SEM, irregularities having an equivalent diameter of 110 nm were confirmed. When the white display particles of Example 1 were similarly used to evaluate the information display panel, the contrast ratio was 4.0, which was insufficient.

<Comparative Example 7>
From the positively charged particles of Example 3, 2.4 parts by weight of a nigrosine compound (Bontron N07: manufactured by Orient Chemical Co., Ltd.) was changed to 0.002 parts by weight of a monomer-soluble charge control agent (Acrybase FCA-201PS: manufactured by Fujikura Kasei). Using the same method as in Example 3, black particles having an average particle diameter of 9.7 μm were obtained. When the surface of this particle was observed with an SEM, irregularities with an equivalent diameter of 90 nm were observed. When the white display particles of Example 1 were similarly used to evaluate the information display panel, the contrast ratio was 3.2, which was insufficient.

<Comparative Example 8>
The same method as in Example 1 except that carbon black (MA100: manufactured by Mitsubishi Chemical) was changed to carbon black (Printex35: manufactured by Degussa) having a primary particle diameter of 31 nm and a DBP adsorption amount of 42 ml / 100 g. Using, black particles having an average particle size of 9.2 μm were obtained. When the surface of the particles was observed with an SEM, irregularities having a diameter equivalent to 100 nm were observed.

  When the white display particles of Example 1 were similarly used to evaluate the information display panel, the contrast ratio was 5.8, which was insufficient.

  The same method as in Example 1 except that carbon black (MA100: manufactured by Mitsubishi Chemical) was changed to carbon black (Printex L6: manufactured by Degussa) having a primary particle diameter of 18 nm and a DBP adsorption amount of 123 ml / 100 g. The black particles having an average particle diameter of 9.2 μm were obtained. When the surface of the particles was observed with an SEM, irregularities having a diameter equivalent to 100 nm were observed.

  When the white display particles of Example 1 were similarly used to evaluate the information display panel, leakage occurred between the substrates, and display was not possible.

  Particles for black display medium and information display panel of the present invention include display units of mobile devices such as notebook computers, PDAs, mobile phones, handy terminals, electronic papers such as electronic books and electronic newspapers, signs, posters, blackboards, etc. Bulletin boards, calculators, home appliances, automobile supplies, etc., point cards, card displays such as IC cards, electronic advertisements, information boards, electronic POPs (Point Of Presence, Point Of Purchase advertising), electronic price tags, electronic shelf labels It is suitably used for electronic musical scores, display units of RF-ID devices, and the like.

(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 an example which imaged the particle | grains for display media of this invention with the scanning electron microscope (SEM). It is a figure which shows an example of the shape of the partition in the information display panel of this invention.

Explanation of symbols

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

Claims (7)

A display medium constituting a display medium used for an information display panel that displays information by moving the display medium by enclosing the display medium between two substrates transparent at least one and applying an electric field to the display medium (1) The particle is a substantially spherical particle obtained by polymerizing a particle raw material containing a monomer, and (acrylic and methacrylic) resin-hydrocarbon resin copolymer or (acrylic and methacrylic) is contained in the particle raw material. System) resin- (acrylic and methacrylic type having hydrocarbon or fluorohydrocarbon in the side chain) resin, and some or all of the monomers have a plurality of polymerization reactive groups in one molecule. It is a functional monomer and has fine irregularities uniformly on the particle surface, and (2) the primary particle diameter relative to the particle constituent resin in the constituent ratio of the particles Together contain 30 (nm) DBP absorption amount of less ¹²⁰ (cm 3 / 100g) the at which carbon black than 4 parts by weight or more, characterized in that it contains a charge control agent less than 60% of the amount of carbon black Particles for black display media.   2. The black display medium particle according to claim 1, wherein the carbon black is contained in an amount of 10 parts by weight or less with respect to a particle constituent resin.   3. The black display medium particle according to claim 1, wherein the charge control agent contains 0.1% or more of the amount of carbon black.   The black display medium particles according to any one of claims 1 to 3, wherein the minute irregularities are convex portions or concave portions having an equivalent diameter of 0.01 to 0.5 µm.   The black display medium particle according to any one of claims 1 to 4, wherein the hydrocarbon resin of the (acrylic and methacrylic) resin-hydrocarbon resin copolymer is a styrene resin.   The particles for black display medium according to any one of claims 1 to 5, wherein the particle diameter of the particles is 0.5 to 50 µm.   An information display panel for displaying information by moving a display medium by enclosing the display medium between two substrates, at least one of which is transparent, and applying an electric field to the display medium. An information display panel, wherein the particles for black display medium according to any one of the above are used alone or together with particles for display media of other colors.