JP2006169463A - Display medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display medium with a memory property which has improved optical characteristics, especially a contrast ratio. <P>SOLUTION: The display medium comprises at least one base material and constituting layers including a liquid crystal layer comprising a binder and a liquid crystal composition dispersed in the binder, wherein at least one layer of the constituting layers comprises a plate crystal having an average aspect ratio of 10-500. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a display medium having a binder and a liquid crystal layer containing a liquid crystal composition dispersed in the binder.

  In recent years, with the increase in the operating speed of personal computers, the spread of network infrastructure, the increase in capacity and price of data storage, information such as documents and images provided on printed paper on paper has become easier to use electronic information. Opportunities to obtain and browse electronic information are increasingly increasing.

  As a means for browsing such electronic information, a light emitting type such as a conventional liquid crystal display, a CRT, or a new organic EL display is mainly used. However, particularly when the electronic information is document information, it is used for a relatively long time. It is necessary to watch the browsing means, and these actions are not necessarily human-friendly means. In general, light-emitting displays have the disadvantages of flickering eyes, inconvenient to carry, limited reading posture, need to focus on a static screen, and increased power consumption when viewed over a long period of time. ing.

As a display means that compensates for these disadvantages, a reflection type display that uses external light and does not consume power for image retention (memory type) is known. Among reflection type displays, a method in which a liquid crystal composition is made into oil droplets and dispersed and held in a binder is called a polymer dispersion type liquid crystal or a scattering type liquid crystal, and various methods are known. (For example, see Patent Documents 1 to 4.)
As a result of examining the techniques disclosed in each of the above-mentioned patent documents in detail, the present inventor can certainly perform image display using the light scattering state and the light transmission state of the liquid crystal. It was found that there was a problem in the optical characteristics.
JP 2003-302625 A JP 7-287214 A JP-A-9-218421 JP 2000-98326 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a display medium with improved optical characteristics, particularly a contrast ratio, in a display medium having a memory property.

  The above object of the present invention is achieved by the following configurations.

(Claim 1)
A display medium having at least one substrate and a constituent layer including a binder and a liquid crystal layer containing a liquid crystal composition dispersed in the binder, wherein at least one of the constituent layers has an average aspect ratio of 10 or more , 500 or less flat crystal.

(Claim 2)
The display medium according to claim 1, wherein the flat crystal is a guanine crystal.

(Claim 3)
The display medium according to claim 1, wherein the liquid crystal composition is a chiral nematic liquid crystal composition having a cholesteric phase.

(Claim 4)
The display according to claim 3, wherein the chiral nematic liquid crystal composition includes a plurality of liquid crystal compositions that selectively reflect at least one kind of light selected from blue light, green light, red light, and yellow light. Medium.

(Claim 5)
5. The display medium according to claim 3, wherein the chiral nematic liquid crystal composition includes a liquid crystal composition that provides dextrorotatory or levorotatory selective reflection. 6.

(Claim 6)
The display medium according to claim 1, wherein a plurality of types of liquid crystal compositions are included in the same liquid crystal layer.

(Claim 7)
The display medium according to claim 1, comprising a plurality of liquid crystal layers containing the dispersed liquid crystal composition.

(Claim 8)
The display medium according to claim 1, wherein the dispersed liquid crystal composition is covered with a microcapsule wall.

(Claim 9)
The display medium according to any one of claims 1 to 8, wherein the binder and a liquid crystal composition dispersed in the binder are disposed between a pair of electrodes.

(Claim 10)
The display medium according to claim 1, further comprising a light shielding layer.

(Claim 11)
The display medium according to claim 10, wherein the light shielding layer is provided between a pair of electrodes.

(Claim 12)
The display medium according to claim 1, wherein at least one electrode is formed by an electrostatic induction type ink jet method having a nozzle diameter of 30 μm or less.

  ADVANTAGE OF THE INVENTION According to this invention, the display medium which improved the optical characteristic, especially contrast ratio can be provided in the display medium with memory property.

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

  As a result of intensive studies in view of the above problems, the present inventor is a display medium having at least one substrate and a constituent layer including a binder and a liquid crystal layer containing a liquid crystal composition dispersed in the binder. A display medium in which a contrast ratio is improved in a display medium having a memory property by using a display medium in which at least one of the constituent layers contains a flat crystal having an average aspect ratio of 10 or more and 500 or less As a result, the present invention has been found.

  That is, in the present invention, in the liquid crystal layer, by allowing the flat crystal to be present in a dispersed state in the binder, the reflectance can be efficiently compensated by orienting the flat surface of the flat crystal parallel to the substrate. In addition, when the flat crystal is dispersed in the liquid crystal composition, the flat structure of the flat crystal is oriented along the liquid crystal molecules. Therefore, when the liquid crystal is in the P state, the flat crystal also reflects and reflects the reflectance. In the Fc state, the flat crystals are also arranged in a direction substantially perpendicular to the substrate surface, and the incident light is transmitted without being reflected, thereby maintaining the black display in the Fc state and, as a result, obtaining a high contrast ratio. I was able to.

  Details of the display medium of the present invention will be described below.

  The display medium of the present invention is formed of at least one substrate and a constituent layer including a binder and a liquid crystal layer containing a liquid crystal composition dispersed in the binder.

  Examples of the constituent layer include a liquid crystal layer containing a dispersed liquid crystal composition, an intermediate layer containing only a binder, a protective layer, a filter layer containing a dye and a pigment, a light shielding layer, and other layers.

〔binder〕
The binder that can be used in the display medium of the present invention is not particularly limited, but a hydrophilic binder is preferably used. Examples thereof include binders described in Research Disclosure (hereinafter abbreviated as RD), Volume 176 Item / 17643 (December 1978), Volume 308 Item / 308119 (December 1989), and JP-A-64. Examples described in pages (71) to (75) of No. 13546.

  Also suitable binders for the present invention are transparent or translucent and generally colorless, natural polymer synthetic resins, polymers and copolymers, and other media forming films such as gelatin, gum arabic, poly (vinyl alcohol), hydroxy Ethyl cellulose, cellulose acetate, cellulose acetate butyrate, poly (vinyl pyrrolidone), casein, starch, poly (acrylic acid), poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid), copoly (styrene-anhydrous Maleic acid), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters), poly (urethane) Kind, fenoki Resins, poly (vinylidene chloride), poly (epoxides), poly (carbonates), poly (vinyl acetate), cellulose esters, and polyamides.

  The binder according to the present invention may be hydrophilic or hydrophobic, but in the present invention, a hydrophobic transparent binder can be used as long as it is incompatible with the liquid crystal composition. Examples of the hydrophobic transparent binder include polyvinyl butyral, cellulose acetate, cellulose acetate butyrate, polyester, polycarbonate, polyacrylic acid, and polyurethane. Among the hydrophobic binders, polyvinyl butyral, cellulose acetate, cellulose acetate butyrate, and polyester are particularly preferably used.

Two or more of these binders may be used in combination, and the coating amount of the binder is preferably 100 g or less per m ² , and particularly preferably 20 g or less.

  In the binder according to the present invention, particularly when a counter electrode is used, it is important to ensure the film strength of the dispersion type liquid crystal-containing layer. However, it is preferable not to use them because of simplification of the process. Gelatin is a preferred binder that can provide a constituent layer having a uniform film thickness in each step of heating, dissolution, coating, cooling setting, and drying. Other examples of gelatin include, for example, polyvinyl alcohols. By using a thickening polysaccharide such as carrageenan or gellan gum in combination, it is possible to take steps similar to those of gelatin, and in this case, a constituent layer having a uniform film thickness can be obtained.

  In addition, examples of the binder used in the present invention include aqueous solvent dispersions such as polyurethane resins, polyacrylic resins, and silicone resins, photo-curing resins, thermosetting resins, and thermoplastic resins.

  The binder may be hardened. When the binder is hardened, the mechanical strength of the binder can be improved without chemically interacting with the liquid crystal composition dispersed in the binder, so that the toughness of the display medium can be further improved.

  When gelatin is used as the binder, examples of preferable hardeners include US Pat. No. 4,678,739, column 41, 4,791,042, JP-A-59-116,655, and 62-. No. 245,261, 61-18,942, 61-249,054, 61-245,153, JP-A-4-218044, and the like. More specifically, aldehyde hardeners (eg, formaldehyde), aziridine hardeners, epoxy hardeners, vinyl sulfone hardeners (eg, N, N′-ethylene-bis (vinylsulfonyl) Acetamide) ethane), N-methylol hardeners (for example, dimethylolurea, etc.), boric acid, metaboric acid, or polymer hardeners (for example, compounds described in JP-A-62-2234157). Can be mentioned. Among these hardeners, it is preferable to use a vinyl sulfone type hardener or a chlorotriazine type hardener alone or in combination. These hardeners are used in an amount of 0.001 to 1 g, preferably 0.005 to 0.5 g, per 1 g of binder.

[Microcapsule]
The liquid crystal composition according to the present invention can be used in a state of being encapsulated in microcapsules.

  As a method for producing a microcapsule that can be used in the present invention, a known method such as a coacervation method, an interfacial polymerization method, or an in-situ method can be used. Among these, the production method by the coacervation method can be preferably used with little chemical influence on the liquid crystal composition which is an oil phase.

  When gelatin is used as one of the binders, coacervates can be produced by hydrophobic interaction with gum arabic, sodium alginate, carrageenan, carboxymethylcellulose, agar, polyvinylbenzenesulfonic acid, maleic anhydride copolymer, and other surfactants. Thereafter, by performing a gelatin hardening reaction using formaldehyde or the above-described gelatin hardener, the coacervated gelatin composite film can be hardened, and the strength of the microcapsule wall can be improved.

  In addition, the interfacial polymerization method can form a microcapsule wall by polymerizing polyamine, polyhydric phenol and the like with a polybasic acid halide, polyisocyanate and the like at the interface between the aqueous phase and the oil phase.

  As an in-situ polymerization method, microcapsules can be formed by crosslinking amide resin, phenol resin alone or a copolymer thereof used for urea-melamine or the like with formaldehyde or glutaraldehyde.

  For the microcapsule wall, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyvinyl alcohol, polyethylene oxide, polypropylene oxide, ethylene-vinyl alcohol copolymer, polyacetal , Acrylic resin, methylcellulose, ethylcellulose, phenolic resin, fluororesin, silicone resin, diene resin, polystyrene-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, polyurethane-based thermoplastic elastomer, polyester-based thermoplastic elastomer, polyphenylene ether, polyphenylene sulfide, Polyethersulfone, polyetherketone, polyarylate, aramid, polyimide, poly- -Microcapsule wall strength is improved by coexisting -phenylene, poly-p-xylene, poly-p-phenylene vinylene, polyhydantoin, polyparabanic acid, polybenzimidazole, polybenzothiazole, polybenzoxadiazole, polyquinoxaline, etc. Can be improved.

  The microcapsules according to the present invention can be dried and classified after being prepared in a solution system. Examples of the classification method include a spray dryer, a rotary dryer, and a band dryer.

[Plate crystal]
The flat crystal according to the present invention has an average aspect ratio of 10 or more and 500 or less, preferably 50 or more and 100 or less. The preferable size of the flat crystal according to the present invention is an average particle diameter of 0.1 to 20 μm and an average thickness of 1 to 50 nm. The average aspect ratio is preferably 50 or more and 100 or less.

  The aspect ratio referred to in the present invention is obtained by the following formula by obtaining the crystal grain size and crystal thickness for each flat crystal by the following method.

Aspect ratio = crystal grain size / crystal thickness In the present invention, the average crystal grain size is the arithmetic average of the grain size ri. However, 3 significant digits and the least significant digits are rounded off, and the number of measured particles is 1,000 or more indiscriminately. The grain size ri here is a diameter when a projected image when viewed from a direction perpendicular to the main plane of the plate crystal is converted into a circular image of the same area. The grain size ri can be obtained by photographing a flat crystal with an electron microscope at a magnification of 10,000 to 70,000 and measuring the crystal diameter on the print or the projected area.

  In the present invention, the projected area and thickness of each tabular crystal for calculating the grain size and aspect ratio of the tabular crystal can be determined by the following method. A sample is prepared by applying a latex ball with a known particle size as an internal standard on a support and a plate crystal so that the main plane is oriented parallel to the substrate, and shadowing the plate crystal by carbon deposition from a certain angle. Then, a replica sample is prepared by a normal replica method. An electron micrograph of the sample is taken, and the projected area and thickness of each plate crystal are obtained using an image processing apparatus or the like. In this case, the projected area of the tabular crystal can be calculated from the projected area of the internal standard, and the thickness of the tabular crystal can be calculated from the internal standard and the shadow length of the tabular crystal.

  The flat crystal used in the present invention may be either organic or inorganic. Specifically, silver halide, silver flake, silica, calcium carbonate, indium tin composite oxide, pearly luster, synthetic or natural mica with titanium dioxide coated on the surface, hexagonal plate basicity Examples thereof include lead carbonate and plate-like fish scale foil. The plate-like fish scale foil is possessed by silver-white fish such as sword fish and carp, and the inside of the rainbow pigment vesicle present in the fish scale foil consists of extremely thin plate-like guanine crystals. This plate-like guanine crystal has very excellent optical characteristics. For example, the crystal itself is colorless, has high reflectivity, and is preferable from the viewpoint of excellent heat resistance, sulfidation resistance, and solvent resistance. This plate-like guanine crystal can increase the reflectivity of the liquid crystal in the planar state, and can greatly improve the contrast.

[Substrate]
Examples of the substrate that can be used in the present invention include polyolefins such as polyethylene and polypropylene, polycarbonates, cellulose acetate, polyethylene terephthalate, polyethylene dinaphthalene dicarboxylate, polyethylene naphthalates, polyvinyl chloride, polyimide, and polyvinyl acetal. Synthetic plastic films such as polystyrene can also be preferably used. Syndiotactic polystyrenes are also preferred. These can be obtained, for example, by the methods described in JP-A Nos. 62-117708, 1-46912 and 1-178505. Further, a metal substrate such as stainless steel, a paper support such as baryta paper and resin coated paper, and a support provided with a reflective layer on the plastic film, supported by JP-A-62-253195 (pages 29-31) The thing described as a body is mentioned. Research Disclosure (hereinafter abbreviated as RD) No. 17643, page 28, ibid. No. 18716, page 647, right column to page 648, left column, and No. 307105, page 879 can also be preferably used. As these supports, those having resistance to curling due to heat treatment of Tg or less as in US Pat. No. 4,141,735 can be used. Further, the surface of these supports may be subjected to surface treatment for the purpose of improving the adhesion between the support and other constituent layers. In the present invention, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, and flame treatment can be used as the surface treatment. Furthermore, the support body described in pages 44 to 149 of publicly known technology No. 5 (issued by Aztec Co., Ltd. on March 22, 1991) can also be used. Furthermore, RDNo. 308119, page 1009, Product Licensing Index, Volume 92, P108, “Supports”, and the like. In addition, a glass substrate or an epoxy resin kneaded with glass can be used.

[Liquid crystal composition]
The liquid crystal composition according to the present invention is preferably a chiral nematic liquid crystal composition having a cholesteric phase.

  A chiral nematic liquid crystal is a typical liquid crystal exhibiting a cholesteric phase, and can be obtained by adding a predetermined amount of a chiral material to a nematic liquid crystal. This chiral nematic liquid crystal generally has a twisted arrangement of rod-like liquid crystal molecules and exhibits a cholesteric phase. When light is incident on this liquid crystal, when light is incident from a direction parallel to the helical axis, light having a wavelength represented by λ = np is selectively reflected (planar state). Here, λ is the wavelength, n is the average refractive index of the liquid crystal molecules, and p is the distance at which the liquid crystal molecules are twisted 360 °. On the other hand, when light is incident from a direction perpendicular to the helical axis, the light is transmitted without being reflected (focal conic state). Display is performed using this selective reflection and transmission.

  The operation mode of the reflective liquid crystal display having a memory property is disclosed in Technical Paper SID International Symposium Technical Paper Vol. 29, page 897. This operation mode is a method of performing display by switching the alignment state of the chiral nematic liquid crystal to either a planar state (light selective reflection state) or a focal conic state (light transmission state). Since the planar state and the focal conic state are stable states, once the liquid crystal is set to any state, the state is maintained semipermanently unless an external force is applied. In other words, it is useful as a reflective liquid crystal display medium having a memory property that once displayed, the displayed image is maintained as it is even when the power is turned off.

  The reflective liquid crystal display medium described in the above document has a structure in which a chiral nematic liquid crystal is sandwiched between a pair of substrates each provided with an electrode. The liquid crystal is changed to a predetermined state (planar state and focal conic state) by controlling the intensity of the electric field and / or the application time.

  When a voltage equal to or higher than a threshold voltage for untwisting the liquid crystal is applied to the liquid crystal for a sufficient time, the liquid crystal is all in a homeotropic state (the long axis direction of the liquid crystal molecules is perpendicular to the substrate). In this state, since there is no memory property, when the electric field is erased, the liquid crystal is twisted. From the homeotropic state, when the electric field is suddenly erased, it becomes a planar state, and when the electric field is gradually erased, it becomes a focal conic state.

  In addition, when a pulse voltage higher than the threshold voltage for solving the twist is applied to the liquid crystal in the focal conic state (a voltage having a pulse width at which some liquid crystals are in a homeotropic state), the liquid crystal in the homeotropic state is The planar state is established after the application of the pulse voltage. By controlling the width of the pulse voltage and / or the height of the voltage, it is possible to adjust the ratio of the liquid crystal in the planar state (display halftone).

  In a liquid crystal-polymer composite film using chiral nematic liquid crystal, the amount of chiral dopant added to the nematic liquid crystal is adjusted, and the helical pitch of the chiral nematic liquid crystal is selected, and the selective reflection wavelengths are, for example, blue light, green light, red, respectively. By adjusting to light and yellow light, the liquid crystal is in a selective reflection state colored in red, green, blue and yellow in the case of the planar arrangement, and a colorless and transparent light transmission state in the case of the focal conic arrangement. -A polymer composite membrane is obtained. A color liquid crystal display device is obtained by sandwiching the liquid crystal-polymer composite film thus obtained between transparent electrodes. In the display medium of the present invention, the chiral nematic liquid crystal composition is composed of a plurality of liquid crystal compositions that selectively reflect at least one kind of light selected from blue light, green light, red light, and yellow light. preferable.

  In addition, by adjusting the amount of chiral dopant added and adjusting the helical pitch of the chiral nematic liquid crystal so that the selective reflection wavelength is infrared light, it is colorless and transparent in the planar arrangement, in the focal conic arrangement, etc. A liquid crystal-binder composite film showing a light scattering state that appears white due to side scattering is obtained. A white display device is obtained by sandwiching the liquid crystal-binder composite film thus obtained between the transparent electrodes.

  The relationship between the helical pitch p (nm) and the selective reflection wavelength λ (nm) is expressed by the following formula (1).

Formula (1)
λ = n × p
In the formula, n represents an average refractive index, and n ² = (n1 ² + n2 ² ) ^1/2 . n1 represents a refractive index when light is incident in the major axis direction of the liquid crystal molecule, and n2 represents a refractive index when light is incident in a direction perpendicular to the major axis direction of the liquid crystal molecule.

  In order to produce a white display device or a color display device of each color, for example, a method of phase-separating the liquid crystal and the binder by sandwiching a mixture of liquid crystal and a binder on a substrate and curing it with a hardener or the like. can do. At this time, if the spacer is sandwiched between the transparent electrodes together with the mixture, the thickness of the liquid crystal-binder composite film can be easily controlled.

  As a chiral dopant to be added to the nematic liquid crystal, a mixture of plural kinds of chiral dopants may be used. The use of multiple types of chiral dopants increases the phase transition temperature of liquid crystals, improves the transparency of the composite film in the transparent state, and particularly speeds up the display switching between the transparent state and the selective reflection state of the color display device. It is effective to do.

  A first display device having a composite film using a left-handed chiral nematic liquid crystal as a color display device of a specific color, and a right-handed chiral hand that selectively reflects light having the same wavelength as that of the left-handed chiral nematic liquid crystal It is also one of preferred embodiments of the present invention to use a laminate of a second display device having a composite film using a nematic liquid crystal. By doing so, the reflectance can be increased and a better color display can be performed. In particular, when blue and red, whose relative visibility is lower than that of green, are strongly displayed, the overall color balance is improved. Therefore, such a multilayer structure is effective in a blue display device or a red display device.

  A smectic liquid crystal may be added to the liquid crystal-binder composite film used in the white display device. By adding the smectic liquid crystal, the transparency of the liquid crystal-binder composite film is improved, and the contrast between the colorless and transparent state and the white state can be increased.

  The film thickness of the liquid crystal-binder composite film used for each color display device is not particularly limited, but the film thickness of the liquid crystal-binder composite film used for the white display device is the film of the liquid crystal-binder composite film used for the color display device. It is desirable to make it larger than the thickness.

  Specific examples of the liquid crystal composition exhibiting a cholesteric phase include compounds described in US Pat. No. 5,695,682.

  Other scattering-type liquid crystal compositions used in the present invention include 4-substituted benzoic acid 4'-substituted phenyl esters, 2- (4-substituted phenyl) -5-substituted pyrimidines, 4-substituted cyclohexanecarboxylic acid 4'-substituted. Biphenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4'-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4'-substituted phenyl ester, 4-substituted biphenyl 4'-substituted cyclohexane, 4- (4-substituted cyclohexane) Carbonyloxy) benzoic acid 4'-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4'-substituted cyclohexyl ester, 4-substituted 4 "-substituted terphenyl, 4-substituted 4'-substituted biphenyl, 4- Substituted phenyl-4'-substituted cyclohexane and the like, and further JP-A-2001-51260 JP-A-8-43846, JP-A-7-4950, JP-A-2000-147476, JP-A-8-160470, JP-A-10-54996, JP-A-2002-221709, JP-A-2001-92383, JP-A-2003-131234, JP-A-2004-77754, JP-A-2004-2771, etc., polymer network liquid crystal (PNLC), polymer-dispersed liquid crystal A liquid crystal composition called (PDLC) can be given.

  In the display medium of the present invention, the liquid crystal composition according to the present invention is present in a state dispersed in a binder. For example, after mixing the liquid crystal and the chiral agent according to the present invention, the mixture can be prepared by adding the mixture to a gelatin solution containing a surfactant and dispersing the mixture using a known disperser.

  Examples of the surfactant used for the dispersion include ionic surfactants such as aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts, and the like. Can be mentioned.

  Examples of the anionic surfactant include fatty acid soap, N-acyl-N-methylglycine salt, N-acyl-N-methyl-β-alanine salt, N-acyl glutamate, acylated peptide, alkyl sulfonic acid Salt, alkylbenzene sulfonate, alkyl naphthalene sulfonate, dialkyl sulfosuccinate, alkyl sulfoacetate, α-olefin sulfonate, N-acylmethyl taurine, sulfated oil, higher alcohol sulfate, secondary Higher alcohol sulfate, alkyl ether sulfate, secondary higher alcohol ethoxy sulfate, polyoxyethylene alkylphenyl ether sulfate, monoglyculate, fatty acid alkylolamide sulfate, alkyl ether phosphate, alkyl phosphate D Stealth salt, lignin sulfonate, formalin condensate of naphthalene sulfonate, formalin condensate of alkyl naphthalene sulfonate, formalin condensate of special aromatic sulfonate (eg Mohr C) creosote oil sulfonate Formalin condensate and the like can be mentioned.

  Examples of amphoteric surfactants include carboxybetaine type, sulfobetaine type, aminocarboxylate, imidazolinium betaine and the like.

  Nonionic activators include, for example, polyoxyethylene secondary alcohol ether, polyoxyethylene alkylphenyl ether, polyoxyethylene sterol ether, polyoxyethylene lanolin derivative polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene glycerin fatty acid ester , Polyoxyethylene castor oil, hydrogenated castor oil, polyoxyethylene sorbitol fatty acid ester, polyethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, sucrose fatty acid ester, fatty acid alkanolamide, poly Oxyethylene fatty acid amide, polyoxyethylene alkylamine, alkylamine oxide Acetylene glycol, block copolymers with acetylene alcohol, ethylene oxide and propylene oxide, and ethylene oxide adduct of alkylphenol.

  For the dispersion, for example, a shearing stirrer, ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, paint shaker, or the like can be used.

  Next, the configuration of the display medium of the present invention will be described.

[Transparent electrode]
In the present invention, a transparent electrode can be used for at least a part of the counter electrode. The transparent electrode is not particularly limited as long as it is transparent and can conduct electricity. For example, Indium Tin Oxide (ITO: Indium Tin Oxide), Indium Zinc Oxide (IZO: Indium Zinc Oxide), Tin Oxide (FTO) ), Indium oxide, zinc oxide, platinum, gold, silver, rhodium, copper, chromium, carbon, aluminum, silicon, amorphous silicon, magnesium, BSO (Bismuth Silicon Oxide), or a mixture thereof. In the mixture, for example, an ITO layer having a thickness of about 50 nm and a silver layer having a thickness of about 50 nm may have a laminated structure.

  Further, a conductive polymer such as a polythiophene-based, polypyrrole-based, polyaniline-based, polyacetylene-based, polyparaphenylene-based, polyselenophenylene-based polymer, or a mixture thereof can be used as the transparent electrode.

  Further, a transparent electrode is produced by applying a liquid in which ITO fine powder fired at 350 ° C. to 800 ° C. is dispersed in a solution containing a solvent or a polymer material to a substrate and volatilizing the solvent or curing the polymer. It is also possible. In this case, the solidification temperature after coating is preferably 40 ° C. or higher and 200 ° C. or lower. ITO fine powder, for example, by mixing tin chloride aqueous solution and indium chloride aqueous solution, adding ammonia etc. to cause coprecipitation reaction while keeping pH at 9, fractionate and wash the resulting hydroxide precipitate Thus, it can be produced by baking at 500 ° C. for 2 hours. By changing the mixing ratio of tin chloride and indium chloride, a fine powder having an arbitrary mixing ratio can be formed. The shape of the fine powder may be any of a granular shape, a needle shape, a plate shape, and a flake shape, and a mixture of a needle shape and a granular shape may be used.

  In addition, a coating liquid in which about 10% of organic indium and organic tin are mixed in a xylol at a mass ratio of 97: 3 is applied on the substrate, and the solvent is volatilized and baked at 100 ° C. or higher and 150 ° C. or lower. A solidifying method can also be preferably used.

  For the purpose of improving the mechanical strength of the electrode, a polymer compound such as a compound species capable of forming a polyurethane resin containing blocked isocyanate or a compound species capable of forming an epoxy resin may be mixed in the coating solution.

  The surface resistance value of the transparent electrode is preferably 500Ω / □ or less, particularly preferably 300Ω / □ or less. The film thickness is preferably 0.2 μm or more and 50 μm or less.

[Production method of electrode]
In order to form a transparent electrode and a metal electrode, a known method can be used. For example, mask deposition may be performed on the substrate by sputtering or the like, or patterning may be performed by photolithography after the entire surface is formed. Electrodes can also be formed by electrolytic plating, electroless plating, printing methods, and ink jet methods.

  After forming an electrode pattern including a catalyst layer having a monomer polymerization ability on a substrate using an inkjet method, a monomer component that is polymerized by the catalyst and becomes a conductive polymer layer after polymerization is added, It is also possible to form a metal electrode pattern by polymerizing and further performing metal plating such as silver on the conductive polymer layer, and the process is greatly reduced because no photoresist or mask pattern is used. It can be simplified.

  When the electrode material is formed by coating, known methods such as a dipping method, a spinner method, a spray method, a roll coater method, a flexographic printing method, and a screen printing method can be used.

[Electrostatic inkjet method]
In the display medium of the present invention, at least one electrode has a liquid discharge head having a nozzle with an internal diameter of 30 μm or less for discharging a charged liquid, supply means for supplying a solution into the nozzle, Preferably, it is formed using a liquid discharge apparatus provided with discharge voltage applying means for applying a discharge voltage to the solution.

  Furthermore, it is preferable that the solution in the nozzle is formed using a discharge device provided with a convex meniscus forming means for forming a state where the solution rises in a convex shape from the nozzle tip.

  In addition, an operation control unit that controls application of a drive voltage for driving the convex meniscus forming unit and application of a discharge voltage by the discharge voltage application unit is provided, and the operation control unit applies the discharge voltage by the discharge voltage application unit. It is also preferable to use a liquid ejection apparatus having a first ejection control unit that applies a driving voltage to the convex meniscus forming means when ejecting liquid droplets while performing the above.

  In addition, an operation control unit that controls driving of the convex meniscus forming unit and voltage application by the discharge voltage applying unit is provided, and the operation control unit is configured to swell the solution by the convex meniscus forming unit and apply the discharge voltage. And a second discharge control unit that performs the operation in synchronization with the liquid discharge device. It is also a preferred form to use a liquid ejection apparatus having a liquid level stabilization control unit that performs operation control for drawing the liquid level inward.

  By producing an electrode pattern using such an electrostatic ink jet, an electrode excellent in on-demand production, having little waste material and excellent in dimensional accuracy can be advantageously obtained.

[Light shielding layer]
The display medium of the present invention can be provided with a light shielding layer. The light shielding may be performed by any method, for example, by applying a metal reflector, a scattering plate, a colored paint on the substrate, or providing a binder constituting layer containing a colored material such as a pigment or a dye. In the present invention, it is preferable to provide this light-shielding layer between a pair of opposing electrodes. In this case, for example, a layer in which carbon black or the like is dispersed is provided in an adjacent layer close to the liquid crystal layer, thereby further absorbing light. Good black display with improved efficiency can be achieved. Moreover, when using the resin substrate with a transparent electrode for a counter electrode, a colored body can be provided on the surface opposite to the liquid crystal layer of the substrate. The color of the light to be blocked may be black for black display, or may be a filter color that compensates for the reflected color of the liquid crystal.

[Display medium drive method]
In the display medium of the present invention, it is preferable that the driving operation of the counter electrode described above is simple matrix driving. In order to drive the display medium of the present invention, for example, Japanese Patent Application Laid-Open Nos. 2003-5222, 2003-228045, 2003-228045, 2002-14323, 2003-29301, 2002-287135. The drive circuit and the drive waveform described in each publication of No. can be applied.

  The simple matrix driving in the present invention is a driving method in which a current is sequentially applied to a circuit in which a positive line including a plurality of positive electrodes and a negative electrode line including a plurality of negative electrodes are opposed to each other in a vertical direction. Say that. By using simple matrix driving, there is an advantage that the circuit configuration and driving IC can be simplified and manufactured at low cost.

  The display medium of the present invention may use active matrix driving. The active matrix drive is a system in which scanning lines, data lines, and current supply lines are formed in a grid pattern, and are driven by TFT circuits provided in each grid pattern. Since switching can be performed for each pixel, there are advantages such as gradation and memory function.

  Next, specific configuration examples of the display medium of the present invention will be described with reference to the drawings. However, the present invention is not limited to the exemplified configurations.

  The display medium of the present invention preferably has a configuration in which a liquid crystal layer including a binder and a liquid crystal composition dispersed in the binder is disposed between a pair of electrodes.

  FIG. 1 is a cross-sectional view showing an example of the structure of a color display medium having a plurality of liquid crystal layers containing dispersed liquid crystal compounds.

  FIG. 1a shows a substrate A having a first electrode 1 and a second electrode 6 as a pair of electrodes, and the second electrode 6 located in the lower observation direction is transparent. An electrode is preferred.

  Between the first electrode 1 and the second electrode 6 at the opposite positions, there are three liquid crystal layers 5, and each of the liquid crystal layers independently has red light dispersed in a binder. A reflective liquid crystal composition 2, a green light reflective liquid crystal composition 3, and a blue light reflective liquid crystal composition 4 are contained. Each of these color light reflection liquid crystal compositions can perform color display by appropriately adjusting the amount of chiral dopant added to the nematic liquid crystal and the threshold voltage applied between the first electrode 1 and the second electrode 6. . Further, in order to remove illegal absorption of each color light reflecting liquid crystal composition and realize optimum color reproduction, a filter layer 7 for color correction may be provided between each liquid crystal layer as shown in FIG. preferable. The arrangement of the green, blue, and red liquid crystal layers 5 can be appropriately selected depending on the spectral characteristics of each liquid crystal composition.

  In the display medium of the present invention, it is one of preferred embodiments that a plurality of liquid crystal compositions are contained in the same liquid crystal layer.

  FIG. 2 is a cross-sectional view illustrating an example of a configuration of a display medium including a light-reflecting liquid crystal composition of three colors in a single liquid crystal layer.

  In FIG. 2 a), a single liquid crystal layer 5 is provided between the first electrode 1 and the second electrode 6, which are one electrode, and the red color dispersed in the binder in the liquid crystal layer 5. The light reflection liquid crystal composition 2, the green light reflection liquid crystal composition 3, and the blue light reflection liquid crystal composition 4 are included.

  FIG. 2 b) shows a mode in which a black light-shielding layer 8 is provided between the liquid crystal layer 5 containing each color light reflecting liquid crystal composition and the first electrode 1. Good black display with improved absorption efficiency. FIG. 2 c) shows a mode in which the base A is arranged on both surfaces, and the black light-shielding layer 8 is provided between the second electrode 6 and the base A at a position away from the observation surface.

  FIG. 3 is a cross-sectional view illustrating an example of the configuration of a color display medium that includes two or more pairs of electrodes and includes a plurality of liquid crystal layers containing a liquid crystal compound.

  3A is an example in which a new electrode is provided between the liquid crystal layer including the green light reflecting liquid crystal composition 3 and the liquid crystal layer including the blue light reflecting liquid crystal composition 2 in the configuration of FIG. 1A. FIG. 3B shows an example of a display medium having a configuration in which each liquid crystal layer is sandwiched between a pair of electrodes. At this time, the electrodes 6, 9, and 10 are all transparent electrodes.

  Although the structure of the display medium shown in FIGS. 1 to 3 described above can be displayed in black and white, it is preferably applied mainly for color display.

  FIG. 4 is a configuration diagram illustrating an example of a configuration of a display medium for monochrome display.

  4A, two liquid crystal layers 5 are provided between the first electrode 1 and the second electrode 6 which are one electrode, and the blue light reflecting liquid crystal composition 4 is included in one layer. The other liquid crystal layer 5 includes a yellow light reflection liquid crystal composition 11 having a complementary color relationship with the blue light reflection liquid crystal composition 4 and displays white and black. In addition, a black light-shielding layer 8 is provided between the first electrode 1 and the liquid crystal layer 5, and by adopting this configuration, a good black display with higher light absorption efficiency can be performed. In FIG. 4 a), an example of black display by the blue light reflective liquid crystal composition 4 and the yellow light reflective liquid crystal composition 11 is shown. For example, a combination of a green light reflective liquid crystal composition and a magenta light reflective liquid crystal composition, Alternatively, a combination of a red light reflection liquid crystal composition and a cyan light reflection liquid crystal composition may be used.

  FIG. 4B shows a form in which the blue light reflection liquid crystal composition 4 and the yellow light reflection liquid crystal composition 11 are simultaneously present in a single layer.

  In the display medium of the present invention, the chiral nematic liquid crystal composition preferably includes a liquid crystal composition that provides dextrorotatory or levorotatory selective reflection.

  FIG. 5 is a cross-sectional view showing an example of the configuration of a black-and-white display medium including a liquid crystal composition providing dextrorotatory or levorotatory selective reflection.

  FIG. 5 a) is an example in which the left-handed liquid crystal composition 12 or the right-handed liquid crystal composition 13 is included in each independent liquid crystal layer, and FIG. Are one example that includes a left-handed liquid crystal composition 12 and a right-handed liquid crystal composition 13, both of which can be applied for monochrome display.

  FIG. 6 is a cross-sectional view showing an example of the configuration of a color display medium including a liquid crystal composition that provides dextrorotatory or levorotatory selective reflection.

  In a) of FIG. 6, a first electrode 1 and a second electrode 6 are provided as a pair of electrodes on the base A, and the first electrode 1 and the second electrode 6 located at the opposed positions are provided. The liquid crystal layer 5 has three layers, and each of the liquid crystal layers independently includes a levorotatory red light reflective liquid crystal composition 14 dispersed in a binder and a dextrorotatory red light reflective liquid crystal. A red reflective layer 16 containing the composition 15, a green reflective layer 19 composed of a levorotatory green light reflective liquid crystal composition 17 and a dextrorotatory green light reflective liquid crystal composition 18 dispersed in a binder, And a blue reflective layer 22 composed of a levorotatory blue light reflective liquid crystal composition 20 and a dextrorotatory blue light reflective liquid crystal composition 21 dispersed in a binder. FIG. 6 b) shows an example in which each left-handed liquid crystal composition and each right-handed liquid crystal composition dispersed in a binder are contained in independent liquid crystal layers.

[Application field of display medium of the present invention]
The display medium of the present invention can be used in ID card related fields, public related fields, transportation related fields, broadcast related fields, payment related fields, distribution and logistics related fields, and the like. Specifically, keys for doors, student ID cards, employee ID cards, various membership cards, convenience store cards, department store cards, vending machine cards, gas station cards, subway and railway cards, bus cards, Examples include cash cards, credit cards, highway cards, driver's licenses, hospital examination cards, health insurance cards, Basic Resident Registers, passports, electronic book terminals, document viewers, signboards and bulletin boards.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
[Preparation of Display Medium 1: Comparative Example]
(Preparation of transparent electrode 1)
An ITO (indium tin oxide) film is formed on the entire surface of polyethylene terephthalate having a thickness of 100 μm by a known sputtering method, and then has an electrode pattern with an electrode interval of 50 μm and an electrode width of 2 mm using a photolithographic method. A transparent electrode 1 was produced.

(Preparation of liquid crystal layer coating solution 1)
Nematic liquid crystal BL012 (manufactured by Merck) exhibiting positive dielectric anisotropy of 60.0% by mass, 20.0% by mass of dextrorotatory chiral agent CB15 (manufactured by Merck), and 20.0% by mass Was mixed well with dextrorotatory chiral agent CE2 (manufactured by Merck & Co., Inc.) to prepare dextrorotatory green reflective liquid crystal composition 1. Next, 8% by mass of photographic gelatin was added to ion-exchanged water, stirred at room temperature, and allowed to stand for 30 minutes to fully swell the gelatin, and then the temperature was raised to 42 ° C. to dissolve the gelatin. It was. To this solution, 12% by mass of isopropyl alcohol containing 10% by mass of alkanol XC (alkyl phthalene sulfonic acid) as a surfactant is added to water, and then the dextrorotatory green reflective liquid crystal composition 1 is added to water. 12 mass% was added with respect to this. While this mixed solution was kept at 42 ° C., it was stirred with a comb-type disperser to obtain a liquid crystal layer coating solution 1 having an average dispersed particle size of 5 μm.

(Preparation of display medium)
The liquid crystal layer coating liquid 1 heated to 42 ° C. is applied on the transparent electrode 1 so as to have a film thickness of 35 μm, and immediately after the coating, the sample is left in an environment of 10 ° C. to form the liquid crystal layer coating liquid in a jelly form. After solidifying, water was dried while maintaining the jelly-like shape. Similarly, an aqueous solution containing 5% by weight of gelatin is applied onto the sample and water is dried, and further, an aqueous solution containing 20% by weight of carbon black and containing 5% by weight of gelatin is applied to remove water. Dried. Using silver paste ink (DW-250H-5 manufactured by Toyobo Co., Ltd.) on the sample, an electrode pattern perpendicular to the electrode pattern of the transparent electrode 1 is formed by screen printing at an electrode interval of 50 μm and an electrode width of 2 mm. A display medium 1 was obtained.

[Preparation of Display Medium 2-6: Present Invention]
In the production of the display medium 1, in place of the liquid crystal layer coating liquid 1, liquid crystal layer coating liquids 2 to 6 in which 5% by mass of each flat crystal having the crystal characteristics shown in Table 1 is added to the liquid crystal layer coating liquid 1 with respect to gelatin. Display media 2 to 6 were produced in the same manner except that was used.

<< Evaluation of display medium >>
(Evaluation of reflectance)
An AC voltage of 50 Hz, 250 msec period was applied to both electrodes of each obtained display medium while changing the voltage value, and the reflectance was measured with a spectrophotometer CM-3700d manufactured by Konica Minolta Sensing Co., Ltd. Values (voltage 1, voltage 2) were determined. Voltage 1 = phase transition voltage from the planar phase to the focal conic phase, and voltage 2 = phase transition voltage from the focal conic phase to the homeotropic phase or the planar phase. Next, the spectral reflection spectrum at voltage 2 was measured, and the reflectance at a wavelength giving the maximum reflectance was obtained. The relative reflectance of each sample when the reflectance of the display medium 1 is 1.00 was determined, and the obtained results are shown in Table 1. Note that the higher the relative reflectance, the brighter the high reflectance.

  As is apparent from the results shown in Table 1, it can be seen that the display medium satisfying the configuration of the present invention has a high reflectance.

Example 2
<< Preparation of Display Medium 7: Comparative Example >>
[Preparation of liquid crystal layer coating solution 7A]
In the preparation of the liquid crystal layer coating liquid 1 described in Example 1, instead of the dextrorotatory green reflective liquid crystal composition 1, nematic liquid crystal E44 (manufactured by Merck) having positive dielectric anisotropy and BL011 (Merck) 7A, respectively) and 44.05 mass%, 19.05 mass%, and dextrorotatory chiral light agent CB15 (manufactured by Merck & Co., Inc.) 36.5 mass%. A liquid crystal layer coating solution 7A was prepared in the same manner except that it was changed to

[Preparation of liquid crystal layer coating solution 7B]
In the preparation of the liquid crystal layer coating liquid 1 described in Example 1, instead of the dextrorotatory green reflective liquid crystal composition 1, nematic liquid crystal E44 (manufactured by Merck) having positive dielectric anisotropy and BL011 (Merck) 7) are respectively 35.35% by mass and 15.15% by mass, and dextrorotatory chiral light agent CB15 (manufactured by Merck) is 49.5% by mass. A liquid crystal coating liquid 7B was prepared in the same manner except that it was changed to

[Preparation of Liquid Crystal Layer Coating Liquid 7]
Liquid crystal layer coating liquid 7 was prepared by mixing liquid crystal layer coating liquid 7A and liquid crystal layer coating liquid 7B prepared above in a mass ratio of 1: 1.3.

[Production of display medium]
In the production of the display medium 1 described in Example 1, the display medium 7 was produced in the same manner except that the liquid crystal layer coating solution 7 prepared above was used instead of the liquid crystal layer coating solution 1.

<< Preparation of display media 8-12 >>
In the production of the display medium 7, in place of the liquid crystal layer coating liquid 7, liquid crystal layer coating liquids 8 to 8 in which 5% by mass of each plate crystal having the crystal characteristics shown in Table 2 is added to the liquid crystal layer coating liquid 7 with respect to gelatin. Display media 8 to 12 were produced in the same manner except that No. 12 was used.

<< Production and Evaluation of Display Medium >>
With respect to the produced display media 7 to 12, the reflectance was evaluated in the same manner as in the method described in Example 1, and when the blue reflectance of the blue reflected light was 1.00, the reflectance of the display medium 7 was 1.00. The relative reflectance of blue of each sample was determined, and the results obtained are shown in Table 2. Note that the higher the relative reflectance, the brighter the high reflectance.

  As is apparent from the results shown in Table 2, it can be seen that the display medium satisfying the configuration of the present invention has a high reflectance.

Example 3
<< Preparation of Display Medium 13: Comparative Example >>
[Preparation of liquid crystal layer coating solution 13A]
69.0% by mass of nematic liquid crystal BL012 (manufactured by Merck) showing positive dielectric anisotropy, 15.5% by mass of right-handed chiral agent CB15 (manufactured by Merck), and right-handed chiral agent CE2 A liquid crystal composition 13 was prepared by mixing 15.5% by mass of liquid crystal (Merck), and then photographic gelatin was 4% by mass with respect to ion-exchanged water, and arabic gum was 1% with respect to water. %, And the mixture was stirred at room temperature and allowed to stand for 30 minutes to sufficiently swell gelatin and arabic gum, and then the temperature was raised to 42 ° C. and dissolved. To this solution, 12% isopropyl alcohol containing 10% by mass of alkanol XC (triisopropylnaphthalenesulfonic acid) as a surfactant was added to water, and then 10% by mass of liquid crystal composition 13 was added to water. . While this mixed solution was kept at 42 ° C., it was stirred with a comb-type disperser to obtain a liquid crystal dispersion solution having an average dispersed particle size of 5 μm. The pH of the liquid crystal dispersion solution was adjusted to 4.05 and stirred for 30 minutes, and then the liquid temperature was lowered to 8 ° C. and further stirred for 30 minutes. To this solution, 15 mg of a hardener (H ₂ C═CHSO ₂ CH ₂ CH (OH) CH ₂ SO ₂ CH═CH ₂ ) was added to 1 g of gelatin, and the mixture was stirred for 5 minutes. The mixture was raised to 0 and stirred for another 30 minutes. Next, the temperature of this solution was raised to 30 ° C. and stirred for 20 minutes to obtain a microcapsule solution containing the liquid crystal composition 13. A gelatin solution was added to the microcapsule solution to adjust the gelatin concentration to 8% by mass with respect to water, thereby obtaining a liquid crystal layer coating solution 13A containing microcapsules enclosing a red light-reflecting liquid crystal composition. .

[Preparation of liquid crystal layer coating solution 13B]
In the preparation of the liquid crystal layer coating liquid 13A, a liquid crystal layer in which a green light reflective liquid crystal composition is encapsulated in microcapsules is the same except that the liquid crystal composition 13 is changed to the liquid crystal composition 1 prepared in Example 1. A coating solution 13B was prepared.

[Preparation of liquid crystal layer coating solution 13C]
In the preparation of the liquid crystal layer coating liquid 13A, the liquid crystal layer containing the blue light-reflecting liquid crystal composition in the microcapsules was similarly used except that the liquid crystal composition 13 was changed to the liquid crystal composition 7B prepared in Example 2. A coating solution 13C was prepared.

[Preparation of liquid crystal layer coating solution 13]
Liquid crystal layer coating liquid 13 was prepared by mixing liquid crystal layer coating liquids 13A, 13B, and 13C prepared above at a mass ratio of 1: 1: 1.

[Production of display medium]
In the production of the display medium 1 described in Example 1, a display medium 13 was produced in the same manner except that the liquid crystal layer coating solution 13 prepared above was used instead of the liquid crystal layer coating solution 1.

<< Preparation of display media 14-18 >>
In the production of the display medium 13, instead of the liquid crystal layer coating solution 13, liquid crystal layer coating solutions 14 to 14 in which 5% by mass of each flat crystal having the crystal characteristics shown in Table 3 is added to gelatin are added to the liquid crystal layer coating solution 13. Display media 14 to 18 were produced in the same manner except that 18 was used.

<< Production and Evaluation of Display Medium >>
When the produced display media 13 to 18 were evaluated for reflectance in the same manner as described in Example 1, the blue reflectance of the display medium 13 was set to 1.00 for blue reflected light. The blue relative reflectance of each sample was determined, and the results obtained are shown in Table 3. Note that the higher the relative reflectance, the brighter the high reflectance.

  As is apparent from the results shown in Table 3, it can be seen that the display medium satisfying the configuration of the present invention has a high reflectance.

  Further, instead of applying the liquid crystal layer coating liquids 13A to 13C, 14A to 14C, 15A to 15C, 16A to 16C, 17A to 17C, and 18A to 18C as a single liquid crystal layer, the liquid crystal layer coating liquids 13A to 13C and 14A, respectively. -14C, 15A to 15C, 16A to 16C, 17A to 17C, 18A to 18C are confirmed to have the same effects as in Table 3 even in each of the display media produced by laminating them as independent liquid crystal layers. I was able to.

Example 4
<< Preparation of Display Medium 19: Comparative Example >>
[Preparation of liquid crystal layer coating solution 19]
In the preparation of the liquid crystal layer coating liquid 7A described in Example 2, the liquid crystal composition was 77.0% by mass of nematic liquid crystal BL012 (manufactured by Merck) showing positive dielectric anisotropy and a dextrorotatory chiral agent CNL. A liquid crystal layer coating liquid 19A having a right-handed green light reflectivity was prepared in exactly the same manner except that it was changed to 23.0% by mass of -611R (manufactured by Asahi Denka Kogyo).

  Next, in the preparation of the liquid crystal layer coating solution 7B described in Example 2, the liquid crystal composition was 77.0% by mass of a nematic liquid crystal BL012 (manufactured by Merck) having a positive dielectric anisotropy, and a left-handed chiral agent. Except for changing to 23.0% by mass of CNL-617L (Asahi Denka Kogyo Co., Ltd.), a left-rotating green light-reflecting liquid crystal layer coating solution 19B was prepared in exactly the same manner.

  The liquid crystal layer coating liquid 19 was prepared by mixing the liquid crystal layer coating liquids 19A and 19B at a mass ratio of 1: 1.

<< Preparation of display media 20-24 >>
In the production of the display medium 19, instead of the liquid crystal layer coating solution 19, a liquid crystal layer coating solution in which 5% by mass of each plate crystal having crystal characteristics was added to the liquid crystal layer coating solution 19 in the same manner as in Examples 1-3. Display media 20 to 24 were produced in the same manner except that the liquid was used.

<< Production and Evaluation of Display Medium >>
As a result of evaluating the reflectance of the produced display media 19 to 24 in the same manner as in the method described in Example 1, the display medium satisfying the configuration of the present invention has a higher reflectance than the comparative example. I was able to confirm.

Example 5
In the production of the display media 1 to 6 described in Example 1, in place of the dextrorotatory green reflective liquid crystal composition 1, it is described in paragraphs [0081] to [0082] of JP-A-5-273576. Display media 25 to 30 were produced in the same manner except that the liquid crystal composition was used, and the reflectance was evaluated in the same manner as in the method described in Example 1. As a result, a display medium satisfying the configuration of the present invention was obtained. Thus, it was confirmed that the reflectance was higher than that of the comparative example, and it was confirmed that the effect of the present invention could be obtained with other than the cholesteric liquid crystal.

Example 6
In the production of the display media 1 to 6 described in Example 1, instead of screen-printing the silver paste, an ink liquid containing silver colloid particles having an average particle diameter of 20 nm is used as an electrostatic ink jet apparatus having a discharge tip nozzle diameter of 15 μm. As a result of producing display media 31 to 36 having the same electrode pattern as in Example 1 and evaluating the reflectance in the same manner as in the method described in Example 1, the display medium satisfying the configuration of the present invention It was confirmed that the reflectance was higher than that of the comparative example.

It is sectional drawing which shows an example of a structure of the color display medium which has multiple structure layers containing the liquid crystal compound disperse | distributed. It is sectional drawing which shows an example of a structure of the display medium containing the light reflection liquid crystal composition of 3 colors in a single structure layer. It is sectional drawing which shows an example of a structure of the color display medium comprised from two or more pairs of electrodes, and having two or more the structural layers containing a liquid crystal compound. It is a block diagram which shows an example of a structure of the display medium for a monochrome display. It is sectional drawing which shows an example of a structure of the black-and-white display medium containing the liquid crystal composition which gives dextrorotatory or levorotatory selective reflection. It is sectional drawing which shows an example of a structure of the color display medium containing the liquid crystal composition which gives dextrorotatory or levorotatory selective reflection.

Explanation of symbols

A substrate 1 first electrode 2 red light reflective liquid crystal composition 3 green light reflective liquid crystal composition 4 blue light reflective liquid crystal composition 5 component layer 6 second electrode (transparent electrode)
7 Filter layer 8 Black light shielding layer 9, 10 Transparent electrode 11 Yellow light reflecting liquid crystal composition 12 Left-handed liquid crystal composition 13 Right-handed liquid crystal composition 14 Left-handed red light-reflecting liquid crystal composition 15 Right handed 16 red reflective liquid crystal composition 16 red reflective layer 17 levorotatory green light reflective liquid crystal composition 18 dextrorotatory green light reflective liquid crystal composition 19 green reflective layer 20 levorotatory blue light reflective liquid crystal composition 21 right-handed blue light reflective liquid crystal composition 22 blue reflective layer

Claims (12)

A display medium having at least one substrate and a constituent layer including a binder and a liquid crystal layer containing a liquid crystal composition dispersed in the binder, wherein at least one of the constituent layers has an average aspect ratio of 10 or more , 500 or less flat crystal. The display medium according to claim 1, wherein the flat crystal is a guanine crystal. The display medium according to claim 1, wherein the liquid crystal composition is a chiral nematic liquid crystal composition having a cholesteric phase. The display according to claim 3, wherein the chiral nematic liquid crystal composition includes a plurality of liquid crystal compositions that selectively reflect at least one kind of light selected from blue light, green light, red light, and yellow light. Medium. 5. The display medium according to claim 3, wherein the chiral nematic liquid crystal composition includes a liquid crystal composition that provides dextrorotatory or levorotatory selective reflection. 6. The display medium according to claim 1, wherein a plurality of types of liquid crystal compositions are included in the same liquid crystal layer. The display medium according to claim 1, comprising a plurality of liquid crystal layers containing the dispersed liquid crystal composition. The display medium according to claim 1, wherein the dispersed liquid crystal composition is covered with a microcapsule wall. The display medium according to any one of claims 1 to 8, wherein the binder and a liquid crystal composition dispersed in the binder are disposed between a pair of electrodes. The display medium according to claim 1, further comprising a light shielding layer. The display medium according to claim 10, wherein the light shielding layer is provided between a pair of electrodes. The display medium according to claim 1, wherein at least one electrode is formed by an electrostatic induction type ink jet method having a nozzle diameter of 30 μm or less.

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