JP2009098518A - Particle for display medium, and panel for information displays using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a particle for a display medium of stable quality, consisting of a composite structure particle in a desired embedded state by quantitatively grasping an appropriate processing temperature range on the basis of a particle diameter of child particles and a deflection temperature under load of a mother particle. <P>SOLUTION: The panel for information display displays information, such as an image, by sealing the display medium constituted to include particles for the display medium having optical reflectivity, and electrostatic chargeability into the space between two sheets of substrates 1, 2, and by applying an electric field to the display medium. In order to achieve the composite structure particle embedded with child particles having a prescribed particle diameter in a surface layer of a mother particle, an appropriate processing temperature range is regulated on the basis of the deflection temperature under the load of the mother particle in the particle for display medium used for the panel for information display. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention encloses a display medium comprising particles for display medium having optical reflectivity and chargeability in a space between two substrates, at least one of which is transparent, and applies an electric field to the display medium. The present invention relates to particles for a display medium constituting a display medium used for an information display panel that displays information such as an image by moving the display medium, and an information display panel using the display medium.

  As an information display device that replaces a liquid crystal display device (LCD), an information display device using a charged particle movement method, a charged particle electrophoresis method, an electrochromic method, a thermal method, a two-color particle rotation method, or the like has been proposed. .

  Among these, the method of moving the charged particles in the gas or moving the charged particles in the liquid can obtain a wide viewing angle close to that of a normal printed material, and consumes less power, compared to the LCD. It is considered as a technology that can be used for next-generation inexpensive information display devices because of its merit such as having a memory function, and is expected to be used for information display for mobile terminals, electronic paper, etc. Yes.

In particular, by enclosing a display medium comprising particles for display medium having optical reflectivity and chargeability in a gas space between two substrates, at least one of which is transparent, and applying an electric field to the display medium, 2. Description of the Related Art An information display panel that displays information such as images by moving a display medium is known as having excellent display memory characteristics and excellent display rewriting response speed. The display medium particles constituting the display medium used in such an information display panel include display medium particles having a composite structure in which child particles having a particle diameter in a predetermined range are embedded in a surface layer of a mother particle. In advance of a person, “particles constituting a display medium used for an information display panel for enclosing a display medium between two opposing substrates, at least one of which is transparent, and moving the display medium to display information such as an image” And a child particle having a particle diameter d ₁ in the range of 0.03 μm <d ₁ <1.00 μm is applied to the surface layer of the mother particle having a particle diameter d ₀ in the range of 1.0 μm <d ₀ <50 μm. _A display medium particle composed of composite particles obtained by adhering or adhering in a state satisfying the condition of ₁ / d ₀ <0.33 ”(see Patent Document 1) has been proposed.

Japanese Patent Application No. 2004-304177

  In the particles for display medium described in Patent Document 1, since the production conditions (processing temperature conditions) for embedding the child particles in the mother particle surface layer have not been quantitatively grasped, the child particles are embedded in the mother particle surface layer under a certain production condition. In such a case, if different child particles (for example, child particles having different particle diameters) are embedded in the surface layer of the mother particle using the same production conditions, the embedded state after processing will be different. Therefore, every time the child particle changes, it is necessary to obtain a production condition (processing temperature condition) that makes a desired embedded state, and the production process becomes complicated.

  The present invention provides a stable quality display medium composed of composite structure particles in a desired embedded state by quantitatively grasping an appropriate processing temperature range based on the particle diameter of the child particles and the deflection temperature under load of the mother particles. The object is to provide particles for use.

  In order to achieve the above object, the display medium particle of the present invention comprises a display medium particle having optical reflectivity and chargeability between gas cavities between two transparent substrates, at least one of which is transparent. A particle for a display medium that constitutes a display medium used for an information display panel that displays information such as an image by moving the display medium by enclosing the medium and applying an electric field to the display medium. In order to realize a composite structure particle in which a child particle having a predetermined particle size smaller than the particle size of the mother particle is embedded in the surface layer of the mother particle as a component, the particle size of the child particle, the deflection temperature under load of the mother particle, A proper processing temperature range is defined based on the above.

As a suitable example of the particles for display medium of the present invention, the appropriate processing temperature range includes a first temperature element based on the square of the particle diameter of the child particles, a second temperature element based on the particle diameter of the child particles, and a lower limit. The lower limit temperature determined by the third temperature element based on the temperature difference between the temperature constant and the deflection temperature under load of the mother particle, the first temperature element based on the square of the particle diameter of the child particle, and the first temperature element based on the particle diameter of the child particle Two temperature elements and an upper limit temperature determined by a fourth temperature element based on a temperature difference between the upper limit temperature constant and the deflection temperature under load of the mother particles, and the appropriate processing temperature range is defined as a processing temperature of t When the particle diameter of the child particles is d and the deflection temperature under load of the mother particles is T, the following formula: −0.002d ² + 1.686d− (140−T) <t <−0.002d ² + 1.686d -(180-T)
There are,

  The information display panel of this invention comprises a display medium using the particles for a display medium according to any one of claims 1 to 3.

  According to the particles for display medium of the present invention, a display medium comprising particles for display medium having optical reflectivity and chargeability is sealed between the gas cavities between two substrates, at least one of which is transparent. In the display medium particles constituting the display medium used for the information display panel that displays information such as images by moving the display medium by applying an electric field to the display medium, the mother particle mainly composed of a resin Appropriate treatment based on the particle size of the child particle and the deflection temperature under load of the mother particle in order to realize the composite structure particle in which the child particle having a predetermined particle size smaller than the particle size of the mother particle is embedded in the surface layer Since the temperature range is defined, even when child particles having different particle diameters are used as child particles embedded in the surface layer of the mother particle, the proper processing temperature range of the child particles can be quantitatively grasped. Accordingly, it is possible to provide particles for a display medium having a stable quality composed of composite structure particles in a desired embedded state.

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

  First, a basic configuration of an information display panel using a display medium including the display medium particles 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 display medium is attracted by an electric field force or a Coulomb force, and the display medium is moved by a change in the electric field direction, whereby information such as an image is displayed. Therefore, it is necessary to design the information display panel so that the display medium can move uniformly and maintain the stability when the display information is rewritten or when the display information is continuously displayed. Here, as the force applied to the particles constituting the display medium, in addition to the force attracting each other by the Coulomb force between the particles, an electric mirror image force between the electrode and the substrate, an intermolecular force, a liquid cross-linking force, gravity and the like can be considered.

  Examples of information display panels using the display medium particles of the present invention as display media are shown in FIGS. 1 (a), 1 (b) to 4 (a), 4 (b), and 5 (a) to 5 (d). This will be explained based on.

  In the examples shown in FIGS. 1A and 1B, display media having at least one kind of particles including charged particles having optical reflectivity and chargeability, and having different optical reflectivity and charging characteristics. 3 is enclosed between substrates (in this case, a white display medium 3W composed of particles of white display medium particles 3Wa and a black display medium 3B composed of particles of black display medium particles 3Ba) are enclosed between substrates. 4 in each cell formed according to the electric field generated by applying a voltage between the electrode 5 (individual electrode) provided on the substrate 1 and the electrode 6 (individual electrode) provided on the substrate 2. Move vertically to 1 and 2. Then, the white display medium 3W is visually recognized by the observer as shown in FIG. 1A, or white display is performed, or the black display medium 3B is visually recognized by the observer as shown in FIG. 1B. The display is black. In addition, in FIG. 1 (a), (b), the partition in front is abbreviate | omitted. The electrode may be provided outside the substrate, inside the substrate, or embedded in the substrate.

  In the example shown in FIGS. 2A and 2B, display media having at least one kind of particles including charged particles having optical reflectivity and chargeability and having different optical reflectivity and charge characteristics from each other. 3 is enclosed between substrates (in this case, a white display medium 3W composed of particles of white display medium particles 3Wa and a black display medium 3B composed of particles of black display medium particles 3Ba) are enclosed between substrates. 4 in each cell formed according to the electric field generated by applying a voltage between the electrode 5 (line electrode) provided on the substrate 1 and the electrode 6 (line electrode) provided on the substrate 2. Move vertically to 1 and 2. Then, the white display medium 3W is visually recognized by the observer as shown in FIG. 2A, or white display is performed, or the black display medium 3B is visually recognized by the observer as shown in FIG. 2B. The display is black. In addition, in FIG. 2 (a), (b), the partition in front is abbreviate | omitted. The electrode may be provided outside the substrate, inside the substrate, or embedded in the substrate.

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

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

  In the example shown in FIGS. 5A to 5D, first, as shown in FIGS. 5A and 5C, from at least one kind of particles including charged particles having optical reflectivity and chargeability. At least two or more types of display mediums 3 having different optical reflectivities and charging characteristics (here, white display medium 3W composed of particles of white display medium particles 3Wa and black display medium particles 3Ba) (Showing a black display medium 3B) between the substrates and in each cell formed by the partition walls 4, external electric field forming means 11 provided outside the substrate 1 and external electric field forming means 12 provided outside the substrate 2 The substrate is moved perpendicularly to the substrates 1 and 2 in accordance with an electric field generated by applying a voltage between them. Then, the white display medium 3W is visually recognized by the observer as shown in FIG. 5B, or white display is performed, or the black display medium 3B is visually recognized by the observer as shown in FIG. 5D. The display is black. In addition, in FIG. 5 (a)-(d), the partition in front is abbreviate | omitted. In addition, a conductive member 13 is provided inside the substrate 1, and a conductive member 14 is provided inside the substrate 2. These conductive members may not be provided.

  Hereinafter, the particles for a display medium, which is a feature of the present invention, will be described in detail. The particles for display medium of the present invention can be applied to the information display panels of FIGS. 1 (a), (b) to 4 (a), (b), and FIGS. 5 (a) to (d), At least one of the information display panels constitutes a display medium in a space between two transparent substrates and is sealed. As the display medium, in the present invention, a display medium including a display medium particle having a composite structure in which a child particle having a predetermined particle diameter is embedded in a surface layer of a mother particle is used. In order to realize the particles, in the present invention, an appropriate processing temperature range is defined as follows based on the particle diameter d of the child particles and the deflection temperature T under load of the mother particles. The deflection temperature under load is a kind of softening temperature of plastic and is a temperature applied to a hard plastic with a relatively high softening temperature. The test method is “JIS K7207-1983: Deflection temperature under load of hard plastic”. It is defined in “Test method”. In the present invention, the temperature when a load of 180 MPa is used is used as the deflection temperature under load.

That is, the appropriate processing temperature range includes the first temperature element based on the square of the particle diameter of the child particle, the second temperature element based on the particle diameter of the child particle, the lower limit temperature constant, and the deflection temperature under load of the mother particle. A lower limit temperature determined by the third temperature element based on the temperature difference, a first temperature element based on the square of the particle diameter of the child particle, a second temperature element based on the particle diameter of the child particle, an upper limit temperature constant, and the mother particle The upper limit temperature determined by the fourth temperature element based on the temperature difference from the deflection temperature under load. Specifically, the appropriate processing temperature range is as follows: when the processing temperature is t, the particle diameter of the child particles is d, and the deflection temperature under load of the mother particles is T, the following formula −0.002d ² +1. (140−T) <t <−0.002d ² + 1.686d− (180−T) − (1)
It is prescribed by.

According to the particles for display medium of the present invention, in order to realize a composite structure particle in which a child particle having a predetermined particle diameter is embedded in the surface layer of the mother particle, the particle diameter of the child particle, the deflection temperature under load of the mother particle, Since the appropriate processing temperature range is defined by the above formula (1) based on the above, the appropriate processing temperature range of the child particles is quantitatively determined for each of the case where the child particles having different particle diameters are used as the child particles embedded in the surface layer of the mother particle. Can grasp. Therefore, as will be demonstrated in the examples described later, the particles for a display medium having a stable quality composed of composite structure particles in a desired embedded state are obtained.
In addition, the information display panel of the present invention is configured by sealing the display medium particles as a display medium in a space between two substrates, at least one of which is transparent. In addition, the information display panel has a stable display quality.

  Hereinafter, each member which comprises the information display panel of this invention using the display medium comprised including the particle | grains for display media of this invention is demonstrated.

  Regarding the substrate, at least one of the substrates is a transparent substrate from which the color of the display medium can be confirmed from the outside of the information display panel, and a material having high visible light transmittance and good heat resistance is preferable. The back substrate as the other substrate may be transparent or opaque. Examples of substrate materials include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfin (PES), polyethylene (PE), polycarbonate (PC), polyimide (PI), acrylic and other polymer sheets, metals Examples thereof include a flexible sheet such as a sheet and a non-flexible inorganic sheet such as glass and quartz. A transparent one is used for the display surface side. 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 when an electrode is provided on an information display panel as required, metals such as aluminum, silver, nickel, copper, and gold, indium tin oxide (ITO), indium oxide, antimony tin oxide (ATO) ), Conductive metal oxides such as zinc-doped indium oxide (IZO), aluminum-doped zinc oxide (AZO), conductive tin oxide, and conductive zinc oxide, and conductive polymers such as polyaniline, polypyrrole, and polythiophene. Are appropriately selected and used. As an electrode forming method, the above-exemplified materials are patterned into a thin film by sputtering, vacuum deposition, CVD (chemical vapor deposition), coating, or the like, or a metal foil (for example, rolled copper foil) is laminated. The method and the method of mixing and apply | coating a electrically conductive agent with a solvent or a synthetic resin binder are used. The electrode provided on the display surface side substrate which is on the viewing side and needs to be transparent 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 can be patterned and is electrically conductive can be suitably used. Note that the electrode thickness may be 0.01 to 10 [mu] m, preferably 0.05 to 5 [mu] m, as long as conductivity can be ensured and light transmittance is not hindered. The material and thickness of the electrode provided on the back side substrate are the same as those of the electrode provided on the display surface side substrate described above, but need not be transparent. In this case, the external voltage input may be superimposed with direct current or alternating current.

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

Next, the display medium particles of the present invention will be described. The display medium particles are used as they are as they are, which are composed of the display medium particles alone or in combination with other particles as a display medium.
The base particles of the display medium particles can contain a charge control agent, a colorant, an inorganic additive, and the like, if necessary, in the resin as the main component. Examples of the resin, the charge control agent, the colorant, and other additives that constitute the display medium particles will be described below.

  Examples of the resin (corresponding to the mother particle resin in the present invention) include urethane resin, urea resin, acrylic resin, polyester resin, acrylic urethane resin, acrylic urethane silicone resin, acrylic urethane fluororesin, acrylic fluororesin, and silicone resin. , Acrylic silicone resin, epoxy resin, polystyrene resin, styrene acrylic resin, polyolefin resin, butyral resin, vinylidene chloride resin, melamine resin, phenol resin, fluorine resin, polycarbonate resin, polysulfone resin, polyether resin, polyamide resin, etc. 2 or more types can also be mixed. In particular, a styrene acrylic resin, an acrylic resin, an acrylic fluororesin, and a polystyrene resin are preferable from the viewpoint of controlling the adhesive force with the substrate.

Examples of positively chargeable charge control agents include polyamine resins, tertiary amino group-containing copolymers, and charge control resins such as quaternary ammonium salt-based copolymers, imidazole compounds, nigrosine dyes, quaternary ammonium salts, and A triaminotriphenylmethane-based compound or the like can be used.
Examples of negatively chargeable charge control agents include sulfonic acid group-containing copolymers, sulfonate group-containing copolymers, carboxylic acid group-containing copolymers, and charge control resins such as carboxylic acid group-containing copolymers, and alkyls. Examples include salicylic acid metal oxides.
Among the above charge control agents, it is preferable to use a charge control resin, and the charge control resin preferably has a content of a functional group imparting chargeability of 0.5 to 15% by weight, and preferably 1 to 10%. More preferably, it is% by weight.
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 salts. System compounds, calixarene compounds, boron-containing compounds (benzyl acid boron complexes), nitroimidazole derivatives, and the like. 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 and 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. The colorant can be blended to produce mother particles of a desired color.

  In addition, it is preferable that the mother particles and the display medium particles of the present invention have an average particle diameter d (0.5) in the range of 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. If the average particle diameter d (0.5) is smaller than this range, the cohesive force between the particles becomes too large, which hinders movement as a display medium.

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

  Furthermore, when using a plurality of display media, among the display medium particles constituting the used display medium, d (0.5) of the display medium particles showing the maximum average particle diameter d (0.5), It is important that the ratio of d (0.5) of the particles for display medium showing the minimum average particle diameter d (0.5) is 10 or less. Even if the particle size distribution Span is reduced, the display medium particles having different charging characteristics move in opposite directions, so that the display medium particles are close in size, and the display medium particles are equivalent in opposite directions. It is preferable that it can be easily moved, and this is the range.

The particle size distribution and the particle size can be obtained from a laser diffraction / scattering method or the like. When 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 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 equal to 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 accompanying charge decay, the saturation amount of the charging behavior of the particles for the display medium is a dominant factor.
As a result of intensive studies, the inventors of the present invention have been able to evaluate the range of proper charging characteristics of display medium particles by measuring the charge amount of display medium particles using the same carrier particles in the blow-off method. I found it.

Furthermore, when applied to an information display panel in which a display medium composed of particles for a display medium is driven in a gas 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, and preferably 50% RH or less for the humidity of the gas in the gap.
For example, in FIG. 1 (a), (b) to FIG. 3 (a), (b), the void portion refers to electrodes 5 and 6 (electrodes of the substrate) from portions sandwiched between the opposing substrate 1 and substrate 2. It refers to the gas portion in contact with the so-called display medium, excluding the occupied portion of the display medium 3, the occupied portion of the partition wall 4 (when the partition wall is provided), and the 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 may be adjusted to 10 to 500 μm, preferably 10 to 200 μm, as long as the display medium can move and maintain the contrast.
The volume occupation ratio of the display medium in the gas space between the opposing substrates is preferably 5 to 70%, more preferably 5 to 60%. When it exceeds 70%, the movement as a display medium is hindered, and when it is less than 5%, the contrast tends to be unclear.

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

[Control of processing temperature when producing particles for display media]
As control factors for controlling the processing temperature at the time of producing the display medium particles, as shown in FIG. 7, for the child particles, there are “particle diameter”, “particle diameter distribution”, “material”, and the like. Examples of the particles include “particle diameter”, “particle diameter distribution”, “material”, and “sphericity”. The operating conditions of the particle production apparatus include “processing time (operating time)”, “number of rotations”, “heat medium temperature (set temperature of temperature control unit)”, and “processing amount (input amount)”. .

[Preparation of particles for display medium (Example, Comparative example)]
“Hosokawa Micron, Mechano-Fusion Mini” is used as a particle production apparatus, and operating conditions are as follows: input amount: 70 (g), volume: 100 (ml), rotation speed: 3500-4000 (rpm), operation time: 60 (min) In addition to using a particle diameter of 8 μm as a mother particle and using silica, crosslinked polystyrene (PS) or the like as a child particle, “from a composite structure particle in which a child particle having a particle diameter d is embedded in the surface layer of the mother particle The display medium particles of Examples 1 to 5 and Comparative Examples 1 and 2 were prepared. The composite structured particles 1, composite structured particles 2, composite structured particles 3 and composite structured particles 4 used in that case are shown in the drawing substitute photos of FIGS. 8 (a) to 8 (d), respectively.

Table 1 shows the particle diameter of the child particles, the deflection temperature under load of the mother particles, and the proper processing temperature range in Examples 1 to 5 and Comparative Examples 1 and 2 of the particles for display media of the present invention.
The particles for display medium of Example 1 are configured as composite structured particles 1, the particle diameter of the child particles is 110 (nm), the deflection temperature under load of the mother particles is 120 (° C.), and the proper processing temperature range is 64 ±. The temperature was 20 (° C.), and the treatment was actually performed at 65 ° C. within the above range.
The particles for display medium of Example 2 are configured as composite structured particles 2, the particle diameter of the child particles is 240 (nm), the deflection temperature under load of the mother particles is 120 (° C.), and the proper processing temperature range is 125 ±. The temperature was 20 (° C.), and the treatment was actually performed at 120 ° C. within the above range.
The particles for display medium of Example 3 are configured as composite structured particles 3, the particle diameter of the child particles is 300 (nm), the deflection temperature under load of the mother particles is 120 (° C.), and the proper processing temperature range is 131 ±. The temperature was 20 (° C.), and the treatment was actually performed at 125 ° C. within the above range.
The particles for display medium of Example 4 are configured as composite structured particles 4, the particle diameter of the child particles is 110 (nm), the deflection temperature under load of the mother particles is 100 (° C.), and the proper processing temperature range is 44 ±. The temperature was 20 (° C.), and the treatment was actually performed at 45 ° C. within the above range.
The particles for display medium of Example 5 are configured as composite structured particles 5, the particle diameter of the child particles is 240 (nm), the deflection temperature under load of the mother particles is 100 (° C.), and the proper processing temperature range is 105 ±. The temperature was 20 (° C.), and the treatment was actually performed at 105 ° C. within the above range.
The display medium particles of Comparative Example 1 are configured as composite structure particles 6, the particle diameter of the child particles is 300 (nm), the deflection temperature under load of the mother particles is 120 (° C.), and the proper processing temperature range is 125 ±. 20 (° C.). However, since the treatment was actually performed at 148 ° C. outside the above range, as shown in the drawing substitute photo in FIG. It became.
The display medium particles of Comparative Example 2 are configured as composite structure particles 7, the particle diameter of the child particles is 300 (nm), the deflection temperature under load of the mother particles is 120 (° C.), and the proper processing temperature range is 125 ±. 20 (° C.). However, since the treatment was actually performed at 100 ° C. outside the above range, embedding did not proceed as shown in the drawing substitute photo of FIG.
The display medium particles of Comparative Example 3 are configured as composite structure particles 8, the particle diameter of the child particles is 110 (nm), the deflection temperature under load of the mother particles is 120 (° C.), and the proper processing temperature range is 64 ±. 20 (° C.). However, since the treatment was actually performed at 85 ° C. outside the above range, as shown in the drawing substitute photograph of FIG. It became.
The particles for display medium of Comparative Example 4 are configured as composite structure particles 9, the particle size of the child particles is 110 (nm), the deflection temperature under load of the mother particles is 120 (° C.), and the proper processing temperature range is 64 ±. 20 (° C.). However, since the treatment was actually performed at 40 ° C. outside the above range, embedding did not proceed as shown in the drawing substitute photo of FIG.
To summarize the above, when the actual processing temperature exceeds the upper limit temperature of the appropriate processing temperature range, “the embedding rate of the child particles on the surface increases and it becomes impossible to control”, “resin alteration and discoloration of resin” Occurs when the actual processing temperature falls below the lower limit temperature of the appropriate processing temperature range. "The embedding of the child particles into the mother particles does not proceed." Problems such as “Even if the embedding progresses, the process takes too much time” occur.

FIG. 9 is a graph showing the relationship between the particle diameter of the child particles and the temperature in the treatment tank in the display medium particles successfully embedded according to the present invention. When the x-axis is the particle diameter (nm) of the child particles and the y-axis is the temperature in the processing tank (° C.), the particle size of each display medium on the graph (particle diameter of the child particles, temperature in the processing tank) is Y = −0.002x ² + 1.686x−43.811 − (2)
Is plotted on the curve represented by

FIGS. 10A and 10B are cross-sectional views and poor embeddings in the case of good embedment of child particles (OK) in the composite structure particles constituting the display medium particles of the examples and comparative examples of the present invention, respectively. It is a schematic diagram which shows the cross section in the case of NG). In the case of good embedding (OK) shown in FIG. 10 (a), it becomes a composite structure particle in which the child particles are completely embedded in the surface layer of the mother particle, but the embedding failure (NG) shown in FIG. In such a case, the child particles are only attached to the surface layer of the mother particle, resulting in a very unstable embedded state.
The particles for display medium of the successful embedding example have the following formula when the particle diameter of the child particle is d (nm) and the deflection temperature under load of the mother particle is T, for example: Treatment temperature = −0.002d ² + 1.686d -(163.8-T)-(3)
It can produce by processing at the processing temperature calculated | required by.
The display medium particles of Example 1 to Example 5 became the display medium particles of the successful embedding example, but the display medium particles of Comparative Example 1 and Comparative Example 2 were the display medium particles of the embedding failure example. became.

  According to this example, regardless of the numerical values of the particle diameter of the child particles and the base particle resin deflection temperature, the appropriate processing temperature range during the production of the display medium particles can be quantitatively grasped by the above equation (1). Therefore, the processing temperature at the time of producing the particles for display medium can be numerically controlled as desired, and the particles for display medium of a successful embedding example can be easily produced. Therefore, stable quality display medium particles composed of composite structure particles in a desired embedded state were obtained.

An information display panel using a display medium composed of particles for a display medium of the present invention is a display for mobile devices such as notebook computers, electronic notebooks, portable information devices called PDA (Personal Digital Assistants), mobile phones, and handy terminals. Departments, electronic books, electronic newspapers, electronic papers such as electronic manuals (electronic instruction manuals), signboards, posters, bulletin boards such as blackboards and whiteboards, electronic desk calculators, display units for home appliances, automobile supplies, point cards, In addition to a card display unit such as an IC card, an electronic advertisement, an information board, an electronic POP (Point Of Presence, Point Of Purchase advertising), an electronic price tag, an electronic shelf label, an electronic score, an RF-ID device display unit, a POS terminal, It is suitably used for display units of various electronic devices such as car navigation devices and watches.
The information display panel using the display medium composed of the display medium particles of the present invention is a simple matrix drive type display panel or static drive type display panel that does not use a switching element in the panel itself, and a thin film transistor (TFT). ) Between electrodes provided corresponding to cells of an information display panel, such as an active matrix drive type display panel using a three-terminal switching element represented by) or a two-terminal switching element represented by a thin film diode (TFD). It is possible to obtain an information display panel of various types of driving methods performed by applying a voltage.

(A), (b) is a figure which shows the fundamental structure of the information display panel of this invention. (A), (b) is a figure which shows the fundamental structure of the information display panel of this invention. (A), (b) is a figure which shows the fundamental structure of the information display panel of this invention. (A), (b) is a figure which shows the fundamental structure of the information display panel of this invention. (A)-(d) is a figure which shows the fundamental structure of the information display panel of this invention. It is a figure which shows an example of the shape of the partition in the information display panel of this invention. It is a figure for demonstrating the control factor for carrying out numerical control of the process temperature at the time of preparation of the particle | grains for display media of this invention. (A)-(d) is the drawing substitute photograph which shows the composite structure particle 1, the composite structure particle 2, the composite structure particle 3, and the composite structure particle 4 used when producing the particle | grains for display media of this invention, respectively. . It is a graph which shows the relationship between the particle diameter of the child particle in the particle | grains for display media with the favorable embedding state produced in this invention, and the temperature in a processing tank. (A), (b) is a case where the cross-section when the embedded state of the child particles is good and the embedded state are poor in the composite structure particles constituting the display medium particles of the examples and comparative examples of the present invention, respectively. It is a schematic diagram which shows the cross section. (A) is a drawing-substituting photograph showing an embedded state of child particles of display medium particles of Comparative Example 1 of the present invention, and (b) is a child image embedded of display medium particles of Comparative Example 2 of the present invention. It is a drawing substitute photograph which shows a loading state. (A) is a drawing-substituting photograph showing an embedded state of child particles of display medium particles of Comparative Example 3 of the present invention, and (b) is a child image embedded of display medium particles of Comparative Example 4 of the present invention. It is a drawing substitute photograph which shows a loading state.

Explanation of symbols

1, 2 Substrate 3 Display medium (particle group)
3W White display medium 3B Black display medium 3Wa White display medium particles 3Ba Black display medium particles 4 Partitions 5, 6 Electrodes 11, 12 External electric field forming means 13, 14 Conductive member 21-1 First cell 21-2 Second Cell 21-3 third cell 22R red color filter 22G green color filter 22B blue color filter

Claims (4)

A display medium comprising particles for display medium having optical reflectivity and chargeability is sealed between gas cavities between two transparent substrates, and display is performed by applying an electric field to the display medium. Display medium particles constituting a display medium used in an information display panel that displays information such as images by moving the medium,
In order to realize a composite structure particle in which a child particle having a predetermined particle size smaller than the particle size of the mother particle is embedded in the surface layer of the mother particle mainly composed of resin, the particle size of the child particle and the load of the mother particle A particle for a display medium, characterized in that an appropriate processing temperature range is defined based on a deflection temperature.   The appropriate processing temperature range includes a first temperature element based on the square of the particle diameter of the child particles, a second temperature element based on the particle diameter of the child particles, and a temperature difference between the lower limit temperature constant and the deflection temperature under load of the mother particles. The lower limit temperature determined by the third temperature element based on the above, the first temperature element based on the square of the particle diameter of the child particle, the second temperature element based on the particle diameter of the child particle, the upper limit temperature constant and the load of the mother particle The display medium particle according to claim 1, wherein the display medium particle is defined by an upper limit temperature determined by a fourth temperature element based on a temperature difference from the deflection temperature. The appropriate processing temperature range is represented by the following formula: −0.002d ² + 1.686d− (140−T), where t is the processing temperature, d is the particle diameter of the child particles, and T is the deflection temperature under load of the mother particles. <T <−0.002d ² + 1.686d− (180−T)
The display medium particle according to claim 1, wherein the display medium particle is defined by:   An information display panel comprising a display medium using the display medium particles according to claim 1.