JP2006313325A - Method of manufacturing particle for display medium, particle for display medium and information display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of stably manufacturing particles for a display medium having low driving voltage and hardly incurring display defect. <P>SOLUTION: With the use of a suspension polymerization method in which a particle raw material containing a copolymer of an (acrylic and methacrylic) resin-a hydrocarbon based resin or a copolymer of an (acrylic and methacrylic) resin-an (acrylic and methacrylic) resin having a hydrocarbon or a fluoro hydrocarbon in their side chains, in the particle raw material containing a multifunctional monomer having a plurality of polymerization reaction groups in one molecule, is suspended in a suspension medium containing one or more surfactants, and then the particle raw material is polymerized to obtain generally spherical particles, the particle raw material is suspended in the suspension medium into an oil drop diameter equal to or greater than a prescribed oil drop diameter, then a substance being decomposed at ≤75°C 10-h half-life temperature and having an effect for initiating or promoting polymerization is added to the suspension medium, then suspension of the particle raw material into the prescribed oil drop diameter and dispersion of the substance are simultaneously performed and then polymerization is performed to obtain the particles for the display medium uniformly having minute uneveness on the surfaces of the particles. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display medium particle manufacturing method, a display medium particle, and an information display device, and in particular, information display such as an image is repeatedly performed by moving the display medium by a force due to an electric field or a Coulomb force. The present invention relates to a method for producing display medium particles constituting a display medium used in a reversible information display device, display medium particles produced by the production method, and an information display device using the display medium particles. is there.

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

  Compared to LCDs, these conventional technologies have advantages such as a wide viewing angle close to that of ordinary printed materials, low power consumption, and a memory function. It is considered as a technology that can be used for mobile phones, and is expected to expand to information display for mobile terminals, electronic paper, and the like. In particular, recently, an electrophoretic method (for example, see Non-Patent Document 1) in which a dispersion liquid composed of dispersion particles and a colored solution is microencapsulated and disposed between opposing substrates has been proposed and expected. It has been.

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

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

In order to solve the various problems described above, an information display device for displaying information by enclosing a display medium between two substrates, at least one of which is transparent, and applying an electric field to the display medium to move the display medium It has been known. As a method for producing particles for a display medium that constitutes a display medium used in an information display device of a type that displays information by moving the display medium by such an electric field, in order to simplify the process and reduce energy consumption, Alternatively, a method using a suspension polymerization method is more effective than a pulverization method in order to directly obtain a target particle size.
In the suspension polymerization method, a particle raw material containing a monomer, a colorant and the like is mechanically suspended in a suspension medium such as water containing 10 wt% or less of a suspension stabilizer such as a surfactant, and then heated. , UV, electron beam, etc., and particles can be obtained by curing in a suspended state under the control of polymerization and taking it out as a solid. In the polymerization, a polymerization initiator is generally used for efficient polymerization. In general, particles produced by suspension polymerization are true spherical particles with a smooth surface.

  In the information display device of the type that displays information by moving the display medium by the electric field as described above, the display medium is set as a particle diameter range in which the display medium (in other words, particles constituting the display medium) can be moved. The particle diameter of the display medium particles to be configured is preferably about 0.5 to 50 μm. When particles with a particle size of less than 0.5 μm are used in the above information display device, the physical adhesion between the particles and between the particles and the substrate increases, and these are separated and moved in the substrate space. Therefore, the energy required to increase the voltage increases the voltage applied to obtain the electric field required to move (drive) the particles. Further, when particles having a particle diameter exceeding 50 μm are used in the information display device, the distance between the substrates must be increased, and a large electric field (in other words, applied voltage) is required to move (drive) the particles. Will be needed. Furthermore, even if the particle diameter is in the range of 0.5 to 50 μm, if the surface smooth particle is used in the information display device, the physical adhesion between the particles and between the particles and the substrate increases. As a result, the energy required to move them apart and move through the substrate space increases, and the voltage applied to obtain the electric field necessary to move (drive) the particles increases. End up.

趙 Kuniori and three others, “New Toner Display Device (I)”, July 21, 1999, Annual Meeting of the Imaging Society of Japan (83 times in total) “Japan Hardcopy’99”, p.249-252

  As a method for solving the above problem, the method that is most simply performed 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 and reduce the adhesion force. When particles for display media used in the above information display device are prepared using this method, transfer of external additives between particles and between particles and substrates, and adhesion of external additives to particle surfaces and substrate surfaces There is a possibility that display defects may occur due to the influence of the above. There is also a method in which a reaction-inert solvent or the like is added to the particle raw material to be subjected to suspension polymerization and then polymerized, and then the solvent is removed by heating or extraction to produce porous particles to make the surface uneven. However, it is not efficient because it requires a process and equipment for removing the solvent and the like.

  Therefore, (acrylic and methacrylic) resin-hydrocarbon resin copolymer or (acrylic and methacrylic) resin- (acrylic and methacrylic having hydrocarbon or fluorohydrocarbon in the side chain) in the particle raw material Resin copolymerization of particles, which is a polyfunctional monomer with some or all of the monomers having multiple polymerization reactive groups in one molecule, makes minute irregularities uniform on the particle surface. The manufacturing method which obtains the particle | grains for display media formed in this was discovered.

  However, when suspension polymerization is performed in the above production method, a substance having an effect of decomposing at a 10-hour half-life temperature of 40 to 75 ° C. in a particle raw material to initiate or accelerate polymerization (polymerization initiator) A particle raw material containing the substance is suspended in a suspension medium and then polymerized to obtain particles. When such a method is used, a polymerization initiator is used. If the particle raw material containing is left untreated, the polymerization proceeds gradually, and there arises a problem that particles having different performances are produced depending on the degree of the progress of the polymerization.

  In the present invention, by forming minute irregularities uniformly on the particle surface during suspension polymerization, it is possible to stably obtain particles for a display medium having a low voltage required for driving and hardly causing display defects. It aims at providing the manufacturing method of the particle | grains for display media.

  In order to achieve the above object, the method for manufacturing an information display panel according to the present invention includes 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. In the method for producing particles for a display medium constituting a display medium used for an information display device for displaying information, the production method includes a monomer, and a part or all of the monomer includes a plurality of polymerization reactive groups in one molecule. A particle raw material which is a multifunctional monomer having, and (acrylic and methacrylic) resin-hydrocarbon resin copolymer or (acrylic and methacrylic) resin in the particle raw material (hydrocarbon in the side chain or Particle raw materials containing copolymers with fluorinated hydrocarbon acrylic and methacrylic resins, containing at least one surfactant. It is a suspension polymerization method in which the particle raw material is polymerized by suspending in a suspension medium to obtain roughly spherical particles, and the particle raw material is suspended in a suspension medium to an oil droplet diameter greater than a predetermined oil droplet diameter. After that, a substance having the effect of decomposing at a 10-hour half-life temperature of 75 ° C. or less to start or accelerate polymerization is added to the suspension medium, and then the suspension of the particle raw material to a predetermined oil droplet diameter and the substance are added. Are dispersed at the same time and then polymerized to obtain particles for a display medium having uniform fine irregularities on the surface of the particles.

  As a preferred example of the method for producing particles for display medium of the present invention, the temperature of the suspension medium when the substance is introduced into the suspension medium is 10 hours half-life temperature or less, and the predetermined oil droplet diameter. Is 0.5 to 50 μm, and the oil droplets may be polymerized to obtain particles having a particle size in the range of 0.5 to 50 μm.

The display medium particles of the present invention are produced by any one of the manufacturing methods of the display medium particles of the present invention and its preferred examples.
As a suitable example of the particles for display medium of the present invention, the minute unevenness is a protrusion or recess having an equivalent diameter of 0.01 to 0.5 μm, and the (acrylic and methacrylic) resin-hydrocarbon. The hydrocarbon resin of the olefin resin copolymer is a styrene resin, the substance having an effect of initiating or promoting the polymerization is an acyl peroxide, and the substance having an effect of initiating or accelerating the polymerization is 1 There may be an azo-based substance having 10 or more carbon atoms in the molecule, and the color of the particles may be one selected from white, red and black.
The information display device of the present invention is configured by using the display medium particles according to any of the above-described display medium particles of the present invention.

  According to the method for producing particles for display medium of the present invention, information is displayed by moving the 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. A method for producing particles for a display medium constituting a display medium used for an information display device, comprising: a monomer, wherein a part or all of the monomer is a polyfunctional monomer having a plurality of polymerization reactive groups in one molecule And (acrylic and methacrylic) resin-hydrocarbon resin copolymer or (acrylic and methacrylic) resin- (acrylic having hydrocarbon or fluorohydrocarbon in the side chain) and After suspending a particle raw material containing a copolymer with a (methacrylic) resin in a suspension medium containing at least one surfactant, the particle raw material is polymerized. In this suspension polymerization method, roughly spherical particles are obtained, and the particle raw material is suspended in an oil droplet diameter larger than a predetermined oil droplet diameter in a suspension medium, and then decomposed at a 10-hour half-life temperature of 75 ° C. or lower. Then, a substance having an effect of initiating or promoting polymerization is added to the suspension medium, and then the suspension of the particle raw material to a predetermined oil droplet diameter and the dispersion of the substance are performed at the same time, and then the polymerization is performed to form a particle surface. In order to obtain particles for a display medium having uniformly fine irregularities on the surface, polymerization does not start until a predetermined temperature is applied. Therefore, as in the case where the particle raw material containing the polymerization initiator is left as it is. There is no change in the performance of the particles due to the degree of polymerization, and stable performance particles can be obtained. Therefore, when the above manufacturing method is used, fixed irregularities that do not drop off are formed during suspension polymerization without steps such as volatilization or extraction of solvents, etc., so that the voltage required for driving the display medium is low. And the particle | grains for display media which are hard to raise | generate a display defect can be produced stably.

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

  First, the configuration of the information display panel of the present invention 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 the applied electric field direction, the charged display medium is attracted by the force of the electric field or the Coulomb force, and the display medium changes the moving direction according to the change of the electric field direction, thereby displaying information such as an image. 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, 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 applicable to the information display device of the present invention will be described with reference to FIGS. 1 (a) and (b) to FIGS. 3 (a) and 3 (b).
In the example shown in FIGS. 1A and 1B, at least two kinds of display media 3 (here, white display medium particles 3Wa) having at least one kind of particles and having different optical reflectance and charging characteristics. A white display medium 3W composed of a group of particles and a black display medium 3B composed of a group of particles 3Ba for black display medium) are perpendicular to the substrates 1 and 2 according to the electric field applied from the outside of the substrates 1 and 2. The black display medium 3B is visually recognized by the observer and black display is performed, or the white display medium 3W is visually recognized by the observer and white display is performed. 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 to form a cell, for example. In addition, in FIG. 1B, the partition in front is omitted.
In the example shown in FIGS. 2A and 2B, at least two kinds of display media 3 (here, white display medium particles 3Wa) having at least one kind of particles and having different optical reflectance and charging characteristics. Between the electrode 5 provided on the substrate 1 and the electrode 6 provided on the substrate 2 is a voltage between the electrode 5 provided on the substrate 1 and the electrode 6 provided on the substrate 2. In accordance with the electric field generated by applying, the substrate is moved perpendicularly to the substrates 1 and 2 so that the black display medium 3B is visually recognized by the observer and black display is performed, or the white display medium 3W is provided to the observer. The white display is made visible. In the example shown in FIG. 2 (b), in addition to the example shown in FIG. 2 (a), a partition 4 is provided between the substrates 1 and 2 to form cells, for example. Further, in FIG. 2 (b), the front partition is omitted.
In the example shown in FIGS. 3A and 3B, one type of display medium 3 (here, particles of white display medium particles 3Wa) having optical reflectivity and chargeability composed of at least one type of particles. A white display medium 3 </ b> W consisting of a group) is parallel to the substrates 1 and 2 according to an electric field generated by applying a voltage between the electrode 5 provided on the substrate 1 and the electrode 6 provided on the substrate 2. The white display medium 3W is visually recognized by the observer and white 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. ing. In the example shown in FIG. 3B, in addition to the example shown in FIG. 3A, for example, a lattice-shaped 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.

  Hereinafter, the manufacturing method of the particle | grains for display media of this invention is demonstrated. The display medium particle manufacturing method of the present invention is an information display in which a display medium is sealed between two substrates, at least one of which is transparent, and information is displayed by moving the display medium by applying an electric field to the display medium. A method for producing particles for a display medium constituting a display medium for use in an apparatus, wherein the production method comprises a polyfunctional monomer containing a monomer, wherein a part or all of the monomer has a plurality of polymerization reactive groups in one molecule. It is a particle raw material, and (acrylic and methacrylic) resin-hydrocarbon resin copolymer or (acrylic and methacrylic) resin- (having hydrocarbon or fluorohydrocarbon in the side chain) After suspending a particle raw material containing a copolymer with an acrylic and methacrylic resin in a suspension medium containing at least one surfactant, Is a suspension polymerization method in which approximately spherical particles are obtained by polymerizing and after suspending the particle raw material in an oil droplet diameter equal to or larger than a predetermined oil droplet diameter in a suspension medium, the 10-hour half-life temperature is 40 to 75. A substance (polymerization initiator) having the effect of decomposing at 0 ° C. to start or accelerate polymerization (polymerization initiator) is added to the suspension medium, and then suspension of the particle raw material to a predetermined oil droplet diameter and dispersion of the substance are performed simultaneously. Further, after that, polymerization is performed to obtain particles for a display medium having uniform fine irregularities on the particle surface.

In the above, it is preferable that the temperature of the suspension medium when the polymerization initiator is added to the suspension medium is equal to or lower than the 10-hour half-life temperature in order not to start the polymerization until a predetermined temperature is applied.
Preferably, the predetermined oil droplet diameter is 0.5 to 50 μm, and the oil droplets are polymerized to obtain particles having a particle diameter in the range of 0.5 to 50 μm.
The display medium particles produced by the above production method are preferably convex portions or concave portions having a diameter equivalent to the diameter of minute irregularities on the particle surface of 0.01 to 0.5 μm. If the size of the projections or recesses on the particle surface is too small, a sufficient adhesion reduction effect cannot be obtained, and if it is too large, the surface of the projections or recesses will adhere and the effect of unevenness will be lost. End up.
The hydrocarbon resin of the above (acrylic and methacrylic) resin-hydrocarbon resin copolymer is preferably a styrene resin in order to make it easy to produce convex portions or concave portions on the particle surface.
As the polymerization initiator, when it dissolves in a suspension medium such as water, emulsion polymerization proceeds, and a large amount of uncolored particles are produced. If this is used for a display medium, the display quality may be deteriorated. Therefore, it is desirable to use an oil-soluble substance in order to prevent this. Therefore, as the polymerization initiator, an acyl peroxide or an azo polymerization initiator having 10 or more carbon atoms in one molecule is suitable.
As the color of the particles, it is preferable to select and use at least one of white, red and black.

  According to the method for producing particles for a display medium of the present invention, since the polymerization is not started until a predetermined temperature is applied by using the polymerization initiator, the particle raw material containing the polymerization initiator described above is used. The performance of the particles does not change due to the degree of progress of the polymerization as in the case of leaving the polymer, and stable performance particles can be obtained. Therefore, when the above manufacturing method is used, fixed irregularities that do not drop off are formed during suspension polymerization without steps such as volatilization or extraction of solvents, etc., so that the voltage required for driving the display medium is low. In addition, it is possible to stably produce display medium particles that are less likely to cause display defects.

  FIG. 4 shows an example in which particles for a display medium used in an information display panel serving as a display unit of the information display device 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.

  Hereinafter, a basic configuration of display medium particles (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 hydrocarbon or fluorohydrocarbon in the side chain 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, fluororesin, polycarbonate resin, polysulfone resin, polyether resin, polyamid Resins. In particular, an acrylic resin, an acrylic fluororesin, a polystyrene resin, and a styrene acrylic resin are suitable from the viewpoint of controlling the adhesive force with the substrate and the ease of suspension polymerization.

  The charge control agent is not particularly limited. Examples of the negative charge control agent include salicylic acid metal complexes, metal-containing azo dyes, metal-containing oil-soluble dyes (including metal ions and metal atoms), and quaternary ammonium salt systems. Examples thereof include compounds, calixarene compounds, boron-containing compounds (benzyl acid boron complexes), nitroimidazole derivatives, and styrene acrylic resins having negatively 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.

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

The particle size distribution and the particle size can be obtained from a laser diffraction / scattering method or the like. When laser light is irradiated onto particles to be measured, a light intensity distribution pattern of diffracted / scattered light is spatially generated, and this light intensity pattern has a corresponding relationship with the particle diameter, so that the particle diameter and particle diameter distribution can be measured. .
Here, the particle size and particle size distribution in the particles of 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 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.
When the display medium is used, the volume occupation ratio of the display medium in the space between the opposing substrates is preferably 5 to 70%, more preferably 5 to 60%. When it exceeds 70%, the movement of the display medium is hindered, and when it is less than 5%, the contrast tends to be unclear.

  Hereinafter, each member which comprises the information display panel used as the object 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 other substrate 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 state becomes clearer.

  EXAMPLES Hereinafter, although Examples 1-4 of this invention and Comparative Examples 1-5 are shown and this invention is demonstrated further more concretely, this invention is not limited to the following Example. In the present invention, an information display panel having a structure in which particles produced by the following method are sealed in a space between panel substrates together with dry air having a humidity of 50% RH or less is used as an information display device. ,evaluated.

<Example 1>
60 parts by weight of methyl methacrylate monomer (Kanto Chemical Reagent) as positively charged particles, and 40 parts by weight (about 25 mol%) of ethylene glycol dimethacrylate (Wako Pure Chemical Reagent) as a multifunctional monomer having a plurality of polymerization reactive groups in one molecule ) 3 parts by weight of a nigrosine compound (Bontron N07: manufactured by Orient Chemical Co., Ltd.) as a positively charged monomer poorly soluble charge control agent is dispersed by a sand mill, and carbon black (MA100: manufactured by Mitsubishi Chemical Co.) 40 is used as a black inorganic pigment-based colorant. 12.5 parts by weight of a master batch in which parts by weight are previously dispersed in 60 parts by weight of methacrylic resin (Delpet 560F: manufactured by Asahi Kasei) and (acrylic and methacrylic) resin- (hydrocarbon or fluorohydrocarbon in the side chain) Copolymers with acrylic and methacrylic resins (Modiper) 600: NOF, hydrogen fluoride component: C 8 _{F 17) 5} was dissolved by weight liquid, polyoxyethylene alkyl ether sulfate as a surfactant comprising a polyoxyalkylene chain and sulfonate in the molecule ( Latemul E-118B (manufactured by Kao) was suspended in purified water at 40 ° C. to which 0.5 wt% was added to obtain a suspension having an oil droplet diameter of about 80 μm. In this suspension, a dispersion obtained by previously dispersing lauryl peroxide (Perroyl L: manufactured by NOF / 10-hour half-life temperature 61.6 ° C.), which is an acyl peroxide, in water is used as the peroxide. After adding so as to be part by weight, the suspension is again suspended so that the oil droplet diameter is about 10 μm, heated and polymerized, filtered and dried, and then used with a classifier (MDS-2: Nippon Pneumatic Industry). Thus, particles 1 having an average particle size of 9.8 μm were obtained in the range of 0.5 to 50 μm. Tg of the resin component of particle 1 was 100 ° C. Moreover, when the surface of the particle | grain 1 was observed by SEM, the unevenness | corrugation with a diameter equivalent diameter of about 100 nm was 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. (About 35 mol%), 5 parts by weight of a phenol-based condensate (Bontron E89: manufactured by Orient Chemical Co., Ltd.) as a negatively charged monomer hardly soluble charge control agent is dispersed by a sand mill, and a white inorganic pigment-based colorant is titanium oxide (type CR-50: made by Ishihara Sangyo Co., Ltd.) 80 parts by weight of methacrylic resin (Delpet 560F: made by Asahi Kasei Co., Ltd.) previously dispersed in 20 parts by weight of masterbatch 25 parts by weight, (acrylic and methacrylic) resin-(in the side chain) Copolymers (Modifier F600) with acrylic or methacrylic resins having hydrocarbons or fluorinated hydrocarbons NOF Corporation, hydrogen fluoride component: C 8 _{F 17) 5} was dissolved by weight liquid, polyoxyethylene alkyl ether sulfate as a surfactant comprising a polyoxyalkylene chain and sulfonate in the molecule (Latemul E -118B: manufactured by Kao) was suspended in purified water at 40 ° C. to which 0.5 wt% had been added to obtain a suspension having an oil droplet diameter of about 80 μm. In this suspension, a dispersion obtained by previously dispersing lauryl peroxide (Perroyl L: manufactured by NOF / 10-hour half-life temperature 61.6 ° C.), which is an acyl peroxide, in water is used as the peroxide. After adding so as to be part by weight, the suspension is again suspended so that the oil droplet diameter is about 10 μm, heated and polymerized, filtered and dried, and then used with a classifier (MDS-2: Nippon Pneumatic Industry). Thus, particles 2 having an average particle size of 9.5 μm were obtained in a particle size range of 0.5 to 50 μm. The Tg of the resin component of Particle 2 was 95 ° C. Moreover, when the surface of the particle | grain 2 was observed by SEM, the unevenness | corrugation whose diameter equivalent diameter is about 150 nm was confirmed.

The particles were charged by friction charging by mixing and stirring the same amount of both particles.
The mixed particles are filled in a cell having a volume content of 30% in a cell which is disposed through a spacer of 100 μm, one is an inner ITO-treated glass substrate and the other is a copper substrate. Obtained. When a power supply is connected to each of the ITO glass substrate and the copper substrate, and a DC 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 moved to the high potential electrode side, and the information display panel observed through the glass substrate was displayed in black. Next, when the potential of the applied voltage was reversed, the particles moved in the opposite directions, and the information display panel was displayed in white. In any case, there was no mixture of particles to be displayed on the ITO glass substrate and particles of different colors, and good display quality was obtained. Further, the voltage was gradually increased, the reflectivity in each display state was measured, and the voltage at which the ratio of the reflectivity during white display and the reflectivity during black display was 8 times was determined as the drive voltage. The voltage was 115V.

<Comparative Example 1>
Do not dissolve (acrylic and methacrylic) resin (acrylic and methacrylic having a hydrocarbon or fluorinated hydrocarbon in the side chain) resin (Modiper F600: manufactured by NOF Corporation) as positively charged particles Except for this, particles 3 having an average particle size of 9.2 μm were obtained in the range of 0.5 to 50 μm in the same manner as the particles 1 described in Example 1. The Tg of the resin component of Particle 3 was 102 ° C. Moreover, when the surface of the particle | grain 3 was observed by SEM, the unevenness | corrugation was not confirmed.

  Do not dissolve (acrylic and methacrylic) resin- (acrylic and methacrylic having a hydrocarbon or fluorinated hydrocarbon in the side chain) resin (Modiper F600: manufactured by NOF Corporation) in particle 2 as negatively charged particles Except for this, particles 4 having an average particle size of 8.9 μm were obtained in the range of 0.5 to 50 μm in the same manner as the particles 2 described in Example 1. The resin component of the particles 4 had a Tg of 96 ° C. Moreover, when the surface of the particle | grain 4 was observed by SEM, the unevenness | corrugation was not confirmed.

The particles were charged by friction charging by mixing and stirring the same amount of both particles.
The mixed particles are filled in a cell having a volume content of 30% in a cell which is disposed through a spacer of 100 μm, one is an inner ITO-treated glass substrate and the other is a copper substrate. 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, positively charged particles are negatively connected to the low potential electrode side. The charged particles moved to the high potential electrode side, and the panel observed through the glass substrate was displayed in black. Next, when the potential of the applied voltage was reversed, the particles moved in the opposite directions and the panel was displayed in white, but the display rewriting was incomplete and good display quality could not be obtained. The voltage was gradually increased, the reflectivity in each display state was measured, and the voltage at which the ratio of the reflectivity during white display to the reflectivity during black display was 8 times as the drive voltage. Was 280V.

<Comparative Example 2>
As positively charged particles, an average of particles having a particle diameter of 0.5 to 50 μm was obtained in exactly the same manner as in Example 1 except that purified water added with the surfactant as a suspension medium for particles 1 was used at 65 ° C. Particles 5 having a particle diameter of 9.5 μm were obtained. Tg of the resin component of the particles 5 was 100 ° C. Further, when the surface of the particle 5 was observed with an SEM, irregularities having an equivalent diameter of about 100 nm were confirmed. However, since the reaction rate of the polymerization initiator was too fast, the polymerization started before suspension to the predetermined oil droplet size, the monomer increased in viscosity, and as a result, the particles did not become nearly spherical, It was confirmed that it had become irregular.

  As negatively charged particles, the average particle size in the range of 0.5 to 50 μm was the same as in Example 1 except that purified water added with the surfactant as a suspension medium for particles 2 was used at 65 ° C. Particles 6 having a particle diameter of 9.1 μm were obtained. The Tg of the resin component of the particles 6 was 95 ° C. Further, when the surface of the particle 6 was observed with an SEM, irregularities having an equivalent diameter of about 150 nm were confirmed. However, since the reaction rate of the polymerization initiator was too fast, the polymerization started before suspension to the predetermined oil droplet size, the monomer increased in viscosity, and as a result, the particles did not become nearly spherical, It was confirmed that it had become irregular.

The particles were charged by friction charging by mixing and stirring the same amount of both particles.
The mixed particles are filled in a cell having a volume content of 30% in a cell which is disposed through a spacer of 100 μm, one is an inner ITO-treated glass substrate and the other is a copper substrate. Obtained. When a power supply is connected to each of the ITO glass substrate and the copper substrate, and a DC 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 moved to the high potential electrode side, and the information display panel observed through the glass substrate was displayed in black. Next, when the potential of the applied voltage was reversed, the particles moved in the opposite directions, and the information display panel was displayed in white. In any case, there was no mixture of particles to be displayed on the ITO glass substrate and particles of different colors, and good display quality was obtained. Further, the voltage was gradually increased, the reflectivity in each display state was measured, and the voltage at which the ratio of the reflectivity during white display and the reflectivity during black display was 8 times was determined as the drive voltage. The voltage was 180V.

<Comparative Example 3>
60 parts by weight of methyl methacrylate monomer (Kanto Chemical Reagent) as positively charged particles, and 40 parts by weight (about 25 mol%) of ethylene glycol dimethacrylate (Wako Pure Chemical Reagent) as a multifunctional monomer having a plurality of polymerization reactive groups in one molecule ) 3 parts by weight of a nigrosine compound (Bontron N07: manufactured by Orient Chemical Co., Ltd.) as a positively charged monomer poorly soluble charge control agent is dispersed by a sand mill, and carbon black (MA100: manufactured by Mitsubishi Chemical Co.) 40 is used as a black inorganic pigment-based colorant. 12.5 parts by weight of a master batch in which parts by weight are previously dispersed in 60 parts by weight of methacrylic resin (Delpet 560F: manufactured by Asahi Kasei) and (acrylic and methacrylic) resin- (hydrocarbon or fluorohydrocarbon in the side chain) Copolymers with acrylic and methacrylic resins (Modiper) 600: NOF, hydrogen fluoride _component: C _{8 F 17)} was dissolved 5 weight, more acyl peroxides in which lauryl peroxide (PEROYL L: product of NOF / 10 hour half-life temperature 61. 6 ° C.) A solution obtained by dissolving 2 parts by weight over 30 minutes was used as a surfactant containing a polyoxyalkylene chain and a sulfonate in the molecule, sodium polyoxyethylene alkyl ether sulfate (Latemul E-118B: manufactured by Kao) Is suspended in 40 ° C. purified water to which 0.5 wt% is added, polymerized, filtered and dried, and then the particle size is in the range of 0.5 to 50 μm using a classifier (MDS-2: Nippon Pneumatic Industry). Thus, particles 7 having an average particle diameter of 9.8 μm were obtained. Tg of the resin component of particle 1 was 100 ° C. Further, when the surface of the particle 7 was observed with an SEM, irregularities having an equivalent diameter of about 100 nm were confirmed, but the surface was not an approximate sphere but an indefinite shape.

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. (About 35 mol%), 5 parts by weight of a phenol-based condensate (Bontron E89: manufactured by Orient Chemical Co., Ltd.) as a negatively charged monomer hardly soluble charge control agent is dispersed by a sand mill, and a white inorganic pigment-based colorant is titanium oxide (type CR-50: made by Ishihara Sangyo Co., Ltd.) 80 parts by weight of methacrylic resin (Delpet 560F: made by Asahi Kasei Co., Ltd.) previously dispersed in 20 parts by weight of masterbatch 25 parts by weight, (acrylic and methacrylic) resin-(in the side chain) Copolymers (Modifier F600) with acrylic or methacrylic resins having hydrocarbons or fluorinated hydrocarbons NOF Corporation, hydrogen fluoride component: After C 8 _{F 17)} is dissolved ₅ weight, more acyl system lauryl peroxide peroxides (PEROYL L: product of NOF / 10 hour half-life temperature of 61.6 ° C. ) 0% of sodium polyoxyethylene alkyl ether sulfate (Latemul E-118B: manufactured by Kao) was used as a surfactant containing 2 parts by weight of the polymer over 30 minutes and containing a polyoxyalkylene chain and a sulfonate in the molecule. After suspending, polymerizing, filtering and drying in purified water at 40 ° C. added with 5 wt%, the average particle size in the range of 0.5 to 50 μm using a classifier (MDS-2: Nippon Pneumatic Industry) Particles 8 having a particle diameter of 9.5 μm were obtained. The Tg of the resin component of the particles 8 was 95 ° C. Further, when the surface of the particle 8 was observed with an SEM, irregularities having an equivalent diameter of about 150 nm were confirmed, but they were not substantially spherical but irregular.

The particles were charged by friction charging by mixing and stirring the same amount of both particles.
The mixed particles are filled in a cell having a volume content of 30% in a cell which is disposed through a spacer of 100 μm, one is an inner ITO-treated glass substrate and the other is a copper substrate. Obtained. When a power supply is connected to each of the ITO glass substrate and the copper substrate, and a DC 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 moved to the high potential electrode side, and the information display panel observed through the glass substrate was displayed in black. Next, when the potential of the applied voltage was reversed, the particles moved in the opposite directions, and the information display panel was displayed in white. In any case, there was no mixture of particles to be displayed on the ITO glass substrate and particles of different colors, and good display quality was obtained. Further, the voltage was gradually increased, the reflectivity in each display state was measured, and the voltage at which the ratio of the reflectivity during white display and the reflectivity during black display was 8 times was determined as the drive voltage. The voltage was 170V.

<Comparative example 4>
As the positively charged particles, lauryl peroxide (Perroyl L: manufactured by NOF Corporation / 10 hours half-life temperature 61.6 ° C.), which is an acyl peroxide, is not used for the particles 1, but t-butyl peroxyisobutylate is used instead. Except for using the rate (Perbutyl IB: manufactured by NOF Corporation / 10-hour half-life temperature 77.3 ° C.), production of particles was attempted in exactly the same manner as in Example 1, but the reactivity of the polymerization initiator was slow. As a result, the monomer was not cured and particles were not formed.

  As a negatively charged particle, lauryl peroxide (Perroyl L: manufactured by NOF Corporation / 10-hour half-life temperature 61.6 ° C.), which is an acyl peroxide, is not used for the particle 2, but t-butyl peroxyisobutylate is used instead. Except for using the rate (Perbutyl IB: manufactured by NOF Corporation / 10-hour half-life temperature 77.3 ° C.), production of particles was attempted in exactly the same manner as in Example 1, but the reactivity of the polymerization initiator was slow. As a result, the monomer was not cured and particles were not formed.

<Example 2>
As the positively charged particles, the lauryl peroxide (Perroyl L: manufactured by NOF / 10-hour half-life temperature 61.6 ° C.), which is an acyl peroxide, is not used for the particles 1, but the number of carbon atoms in one molecule is used instead. Except for using azobisdimethylvaleronitrile (V-65: manufactured by Wako Pure Chemical Industries, Ltd./10-hour half-life temperature 51 ° C.), which is 10 or more azo substances, the particle size of 0. Particles 9 having an average particle diameter of 9.0 μm were obtained in the range of 5 to 50 μm. Tg of the resin component of the particles 9 was 100 ° C. Further, when the surface of the particle 9 was observed with an SEM, irregularities having an equivalent diameter of about 200 nm were confirmed.

  As the negatively charged particles, lauryl peroxide (Perroyl L: manufactured by NOF / 10/10 half-life temperature 61.6 ° C.), which is an acyl peroxide, is not used for the particles 2, but the number of carbon atoms in one molecule is used instead. Except for using azobisdimethylvaleronitrile (V-65: manufactured by Wako Pure Chemical Industries, Ltd./10-hour half-life temperature 51 ° C.), which is 10 or more azo substances, the particle size of 0. Particles 10 having an average particle diameter of 9.6 μm were obtained in the range of 5 to 50 μm. The Tg of the resin component of the particles 10 was 95 ° C. Further, when the surface of the particle 10 was observed with an SEM, irregularities having an equivalent diameter of about 200 nm were confirmed.

The particles were charged by friction charging by mixing and stirring the same amount of both particles.
The mixed particles are filled in a cell having a volume content of 30% in a cell which is disposed through a spacer of 100 μm, one is an inner ITO-treated glass substrate and the other is a copper substrate. Obtained. When a power supply is connected to each of the ITO glass substrate and the copper substrate, and a DC 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 moved to the high potential electrode side, and the information display panel observed through the glass substrate was displayed in black. Next, when the potential of the applied voltage was reversed, the particles moved in the opposite directions, and the information display panel was displayed in white. In any case, there was no mixture of particles to be displayed on the ITO glass substrate and particles of different colors, and good display quality was obtained. Further, the voltage was gradually increased, the reflectivity in each display state was measured, and the voltage at which the ratio of the reflectivity during white display and the reflectivity during black display was 8 times was determined as the drive voltage. The voltage was 110V.

<Comparative Example 5>
As the positively charged particles, the lauryl peroxide (Perroyl L: manufactured by NOF / 10-hour half-life temperature 61.6 ° C.), which is an acyl peroxide, is not used for the particles 1, but the number of carbon atoms in one molecule is used instead. A particle size of 0 in the same manner as in Example 1 except that azobisisobutyronitrile (V-60: manufactured by Wako Pure Chemical Industries, Ltd./10 hour half-life temperature 65 ° C.), which is an azo-based material of 10 or less, was used. Particles 11 having an average particle diameter of 9.9 μm were obtained in the range of 0.5 to 50 μm. The Tg of the resin component of the particles 11 was 100 ° C. Moreover, when the surface of the particle | grains 11 was observed by SEM, the unevenness | corrugation whose diameter equivalent diameter is about 200 nm was confirmed. Moreover, since the polymerization initiator was insufficient in hydrophobicity, it was confirmed that fine particles produced as a by-product by emulsion polymerization could not be separated by classification.

  As the negatively charged particles, lauryl peroxide (Perroyl L: manufactured by NOF / 10/10 half-life temperature 61.6 ° C.), which is an acyl peroxide, is not used for the particles 2, but the number of carbon atoms in one molecule is used instead. A particle size of 0 in the same manner as in Example 1 except that azobisisobutyronitrile (V-60: manufactured by Wako Pure Chemical Industries, Ltd./10 hour half-life temperature 65 ° C.), which is an azo-based material of 10 or less, was used. Particles 12 having an average particle size of 9.6 μm were obtained in a range of 0.5 to 50 μm. The Tg of the resin component of the particles 12 was 95 ° C. Moreover, when the surface of the particle | grains 12 was observed by SEM, the unevenness | corrugation with a diameter equivalent diameter of about 200 nm was confirmed. Moreover, since the polymerization initiator was insufficient in hydrophobicity, it was confirmed that fine particles produced as a by-product by emulsion polymerization could not be separated by classification.

The particles were charged by friction charging by mixing and stirring the same amount of both particles.
The mixed particles are filled in a cell having a volume content of 30% in a cell which is disposed through a spacer of 100 μm, one is an inner ITO-treated glass substrate and the other is a copper substrate. Obtained. When a power supply is connected to each of the ITO glass substrate and the copper substrate, and a DC 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 moved to the high potential electrode side, and the information display panel observed through the glass substrate was displayed in black. Next, when the potential of the applied voltage was reversed, the particles moved in the opposite directions, and the information display panel was displayed in white. In any case, there was no mixture of particles to be displayed on the ITO glass substrate and particles of different colors, and good display quality was obtained. In addition, the reflectance was observed by gradually increasing the voltage. At a voltage of 500 V or less, the voltage at which the ratio of the reflectance during white display to the reflectance during black display is 8 times due to a decrease in contrast due to fine particles. Could not be found.

<Example 3>
As the positively charged particles, a copolymer of (acrylic and methacrylic) resin- (acrylic and methacrylic having a hydrocarbon or fluorinated hydrocarbon in the side chain) resin (Modiper F600: manufactured by NOF Corporation) is used as the positively charged particle In the same manner as in Example 1 except that an acrylic styrene resin (Stylac AS-767: manufactured by Asahi Kasei) was used instead as the (acrylic and methacrylic) resin-hydrocarbon resin copolymer. Particles 13 having an average particle diameter of 9.8 μm were obtained in the range of 0.5 to 50 μm. The Tg of the resin component of the particles 13 was 100 ° C. Further, when the surface of the particle 13 was observed with an SEM, irregularities having an equivalent diameter of about 150 nm were confirmed.

  As the negatively charged particles, a copolymer (Modiper F600: manufactured by NOF Corporation) of (acrylic and methacrylic) resin- (acrylic and methacrylic resin having a hydrocarbon or fluorinated hydrocarbon in the side chain) is used as the particle 2 In the same manner as in Example 1 except that an acrylic styrene resin (Stylac AS-767: manufactured by Asahi Kasei) was used instead as the (acrylic and methacrylic) resin-hydrocarbon resin copolymer. Particles 14 having an average particle diameter of 9.2 μm were obtained in the range of 0.5 to 50 μm. The Tg of the resin component of the particles 14 was 95 ° C. Further, when the surface of the particle 14 was observed with an SEM, irregularities having an equivalent diameter of about 150 nm were confirmed.

The particles were charged by friction charging by mixing and stirring the same amount of both particles.
The mixed particles are filled in a cell having a volume content of 30% in a cell which is disposed through a spacer of 100 μm, one is an inner ITO-treated glass substrate and the other is a copper substrate. Obtained. When a power supply is connected to each of the ITO glass substrate and the copper substrate, and a DC 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 moved to the high potential electrode side, and the information display panel observed through the glass substrate was displayed in black. Next, when the potential of the applied voltage was reversed, the particles moved in the opposite directions, and the information display panel was displayed in white. In any case, there was no mixture of particles to be displayed on the ITO glass substrate and particles of different colors, and good display quality was obtained. Further, the voltage was gradually increased, the reflectivity in each display state was measured, and the voltage at which the ratio of the reflectivity during white display and the reflectivity during black display was 8 times was determined as the drive voltage. The voltage was 110V.

<Example 4>
As positively charged particles, instead of using carbon black (MA100: manufactured by Mitsubishi Chemical), which is a black inorganic pigment-based colorant for particles 1, iron oxide (TAROX R-516-L: manufactured by Titanium Industry) is used as a red colorant. Except for this point, particles 15 were obtained in exactly the same manner as in Example 1. Particles of 500 nm or less were not confirmed. Further, when the surface of the particle 15 was observed with an SEM, irregularities having an equivalent diameter of about 100 nm were confirmed.
As the negatively charged particles, the particles 2 described in Example 1 were used.

The particles were charged by friction charging by mixing and stirring the same amount of both particles.
The mixed particles are filled in a cell having a volume content of 30% in a cell which is disposed through a spacer of 100 μm, one is an inner ITO-treated glass substrate and the other is a copper substrate. Obtained. When a power supply is connected to each of the ITO glass substrate and the copper substrate, and a DC 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 moved to the high potential electrode side, and the information display panel observed through the glass substrate was displayed in red. Next, when the potential of the applied voltage was reversed, the particles moved in the opposite directions, and the information display panel was displayed in white. In any case, there was no mixture of particles to be displayed on the ITO glass substrate and particles of different colors, and good display quality was obtained. Further, the voltage was gradually increased, the reflectance in each display state was measured, and the voltage at which the ratio of the reflectance during white display and the reflectance during red display was 8 times was determined as the drive voltage. The voltage was 125V.

In summary, the particles for display media of Example 1, Example 2, Example 3, and Example 4 were uniformly formed with minute irregularities on the particle surface, and the driving voltage was low. As a result, it was found that the particles for display media hardly cause display defects.
On the other hand, the particles for display medium of Comparative Example 1 have no minute irregularities on the particle surface, and since this was used as a display medium, the drive voltage was high. In the display medium particles of Comparative Example 2 and Comparative Example 3, fine irregularities were formed on the particle surface, but the particles were not substantially spherical. Since it was high, it was a display medium particle that hardly caused a display defect, and Comparative Example 4 could not form a particle itself, and the display medium particle of Comparative Example 5 was very small on the particle surface. It was found that fine irregularities were formed but the fine particles remained without being separated and the drive voltage could not be found due to the decrease in contrast due to the fine particles, resulting in display medium particles that hardly caused display defects.

  Particles for display medium produced by the production method of the present invention, and an information display panel and information display device using the same are provided for display devices of mobile devices such as notebook computers, PDAs, mobile phones, handy terminals, electronic books, and electronic newspapers. Electronic paper, signboards, posters, bulletin boards such as blackboards, calculators, home appliances, display parts for automobiles, card displays such as point cards, IC cards, electronic advertisements, electronic POPs (Point Of Presence, Point Of Purchase) advertising), an electronic shelf label, an information board, an electronic price tag, an electronic score, and a display unit of an RF-ID device.

(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 manufactured with the manufacturing method 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 Substrate 2 Substrate 3 Display medium (particle group)
3W White display medium 3B Black display medium 3Wa White display medium particle 3Ba Black display medium particle 4 Partition 5 Electrode 6 Electrode

Claims (12)

Particles for display medium constituting a display medium used for an information display device that displays information by enclosing a display medium between two transparent substrates and applying an electric field to the display medium In the manufacturing method of
The production method includes a particle raw material containing a monomer, and a part or all of the monomer is a polyfunctional monomer having a plurality of polymerization reactive groups in one molecule, and the particle raw material includes (acrylic and methacrylic). System) -resin-hydrocarbon resin copolymer or (acrylic and methacrylic) resin- (acrylic and methacrylic resin having a hydrocarbon or fluorohydrocarbon in the side chain) This is a suspension polymerization method in which after suspending in a suspension medium containing one or more surfactants, the particle raw material is polymerized to obtain roughly spherical particles, and the particle raw material is added to the suspension medium in predetermined oil droplets. After suspending in an oil droplet diameter larger than the diameter, a substance having an effect of decomposing at 10 hours half-life temperature of 75 ° C. or less and initiating or accelerating polymerization is added to the suspension medium. A particle for a display medium, characterized in that the suspension to a constant oil droplet size and the dispersion of the substance are simultaneously performed and then polymerized to obtain particles for a display medium having uniform fine irregularities on the particle surface. Production method.   The method for producing particles for a display medium according to claim 1, wherein the temperature of the suspension medium when the substance is charged into the suspension medium is 10 hours half-life temperature or less.   2. The display medium particle according to claim 1, wherein the predetermined oil droplet diameter is 0.5 to 50 [mu] m, and the oil droplet is polymerized to obtain particles having a particle diameter in the range of 0.5 to 50 [mu] m. Manufacturing method.   A particle for a display medium, which is produced by the production method according to claim 1.   The display medium particle according to claim 4, wherein the minute unevenness is a protrusion or a recess having an equivalent diameter of 0.01 to 0.5 μm.   6. The display medium particle according to claim 4, wherein the hydrocarbon resin of the (acrylic and methacrylic) resin-hydrocarbon resin copolymer is a styrene resin.   The display medium particle according to claim 4, wherein the substance having an effect of initiating or promoting the polymerization is an acyl peroxide.   The display medium particle according to any one of claims 4 to 6, wherein the substance having an effect of initiating or promoting the polymerization is an azo substance having 10 or more carbon atoms in one molecule.   The particle for display medium according to any one of claims 4 to 8, wherein the color of the particle is white.   The particle for display medium according to any one of claims 4 to 8, wherein the color of the particle is black.   The particle for display medium according to any one of claims 4 to 8, wherein the color of the particle is red.   An information display device using the display medium particle according to any one of claims 4 to 11.