JP2008033083A - Display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the display element of an ED system having simple constitution structure, allowing low-voltage driving, having high display contrast and white display reflectance, and is superior in image resolution. <P>SOLUTION: In the display element, a nonconductive metal oxide layer 2 is formed on at least one of counter electrodes a substantially vertical porous structure in which an aspect ratio (D/L) of a depth D to an aperture width L is ≥2 and ≤1,500. The nonconductive metal oxide layer 2 is not directly brought into contact with at least one of the counter electrodes or a substrate holding the electrode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrochemical display element utilizing silver dissolution precipitation.

  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 increasing more and more.

  As a means for browsing such electronic information, a conventional liquid crystal display or CRT, and in recent years, a light emitting type such as an organic EL display is mainly used. In particular, when the electronic information is document information, it is relatively long time. It is necessary to pay close attention to this browsing means, and these actions are not necessarily human-friendly means. Generally, as a drawback of light-emitting displays, eyes flicker due to flickering, inconvenient to carry, reading posture is limited It is known that it is necessary to adjust the line of sight to a still screen, and that power consumption increases when read for a long time.

  As a display means that compensates for these drawbacks, a reflection type display that uses external light and does not consume power for image retention (memory type) is known, but has sufficient performance for the following reasons. It's hard to say.

  That is, the method using a polarizing plate such as a reflective liquid crystal has a low reflectance of about 40% and is difficult to display white, and many of the production methods used for producing the constituent members are not easy. In addition, the polymer dispersed liquid crystal requires a high voltage and utilizes the difference in refractive index between organic substances, so that the resulting image has insufficient contrast. In addition, the polymer network type liquid crystal has problems such as a high voltage and a complicated TFT circuit required to improve the memory performance. In addition, a display element based on electrophoresis requires a high voltage of 10 V or more, and there is a concern about durability due to electrophoretic particle aggregation. In addition, the electrochromic display element can be driven at a low voltage of 3 V or less, but the color quality of black or color (for example, yellow, magenta, cyan, blue, green, red, etc.) is not sufficient, and the memory There is a concern that a complicated film configuration such as a vapor deposition film is necessary for the display cell in order to ensure the property.

  As a display method that eliminates the drawbacks of each of the above-described methods, an electrodeposition (hereinafter abbreviated as ED) method that utilizes dissolution or precipitation of a metal or a metal salt is known. The ED method can be driven at a low voltage of 3 V or less, has advantages such as a simple cell configuration, excellent black-white contrast and black quality, and various methods have been disclosed (for example, Patent Document 1). -3)).

As a result of detailed examination of each technique disclosed in each of the above-mentioned patent documents, the present inventor has produced a lateral electric field along the electrode surface in addition to the electric field generated in the vertical direction between the electrodes in the conventional technique. It has been found that this has the disadvantage of reducing the image resolution. In particular, it has been found that repeated display driving causes a shift in gray scale chromaticity, which is a major obstacle to realizing a high-quality display element.
U.S. Pat. No. 4,240,716 Japanese Patent No. 3428603 JP 2003-241227 A

  The present invention has been made in view of the above problems, and an object thereof is an ED display element that has a simple member configuration, can be driven at a low voltage, has high display contrast, and high white display reflectance, and has an image resolution. An object of the present invention is to provide an excellent display element.

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

  1. Electrochemical display that has an electrolyte containing silver or a compound containing silver in the chemical structure between the counter electrodes, and generates a potential difference between the counter electrodes to cause dissolution and precipitation of silver and display an image. A non-conductive metal oxide having a substantially vertical porous structure, wherein the aspect ratio (D / L) of the depth D to the opening width L is 2 or more and 1500 or less on one electrode of the counter electrode A display element, wherein a layer is formed, and the nonconductive metal oxide layer is not in direct contact with at least one electrode of the counter electrode or a substrate holding the electrode.

  2. 2. The display element according to 1 above, wherein the opening width L is 10 nm or more and 300 nm or less.

  3. 3. The display element according to 1 or 2, wherein the apertures of the substantially vertical porous structure are an array having a two-dimensional periodicity.

  4). 4. The display element according to 3 above, wherein the aperture ratio of the aperture is 80% or more.

  5. 5. The display element according to any one of 1 to 4, wherein the nonconductive metal oxide layer is an alumina oxide layer.

  6). 6. The display element according to any one of 1 to 5, further comprising a porous white scattering layer between the nonconductive metal oxide layer and the counter electrode.

  7). 7. The display element according to 6 above, wherein the porous white scattering layer is a titanium oxide nanoporous layer.

  8). The electrolyte does not substantially contain iodine ions, and at least one of the compounds represented by the following general formula (1) or (2) and at least one of the compounds represented by the following general formula (3) or (4) The display element according to any one of 1 to 7 above, which contains one kind.

[Wherein, L represents an oxygen atom or CH ₂ , and R _{1 to} R ₄ each represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group, or an alkoxy group. ]

[Wherein, R ₅ and R ₆ each represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group or an alkoxy group. ]
General formula (3)
R ₇ -S-R ₈
[Wherein R ₇ and R ₈ each represents a substituted or unsubstituted hydrocarbon group. However, when a ring containing an S atom is formed, an aromatic group is not taken. ]

[Wherein, M represents a hydrogen atom, a metal atom or quaternary ammonium. Z represents a nitrogen-containing heterocyclic ring. n represents an integer of 0 to 5, and R ₉ represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkylcarbonamide group, an arylcarbonamide group, an alkylsulfonamide group, an arylsulfonamide group, an alkoxy group, an aryloxy group Group, alkylthio group, arylthio group, alkylcarbamoyl group, arylcarbamoyl group, carbamoyl group, alkylsulfamoyl group, arylsulfamoyl group, sulfamoyl group, cyano group, alkylsulfonyl group, arylsulfonyl group, alkoxycarbonyl group, aryl Represents an oxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group, an acyloxy group, a carboxyl group, a carbonyl group, a sulfonyl group, an amino group, a hydroxy group or a heterocyclic group, and when n is 2 or more, each R ₉ is They may be the same or different, and may be linked together to form a condensed ring. ]

  According to the present invention, it is possible to provide an ED display element that has a simple member configuration, can be driven at a low voltage, has a high display contrast, and a high white display reflectance, and has an excellent image resolution.

  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 has an electrolyte containing silver or a compound containing silver in a chemical structure between the counter electrodes, and generates a potential difference between the counter electrodes. An electrochemical display element that causes silver dissolution and precipitation to display an image, and has an aspect ratio (D / L) of a depth D to an opening width L of 2 or more on one electrode of the counter electrode A nonconductive metal oxide layer having a substantially vertical porous structure of 1500 or less is formed, and the nonconductive metal oxide layer is not in direct contact with at least one electrode of the counter electrode or a substrate holding the electrode It is possible to realize a display element with an excellent image resolution, which is an ED display element that can be driven with a simple member configuration, low voltage, high display contrast and white display reflectance. Heading It is up to, which led to the present invention.

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

[Non-conductive metal oxide layer]
In the display element of the present invention, a non-conductive material having a substantially vertical porous structure in which the aspect ratio (D / L) of the depth D to the opening width L is 2 or more and 1500 or less on one electrode of the counter electrode. It has a metal oxide layer.

  In the present invention, the substantially vertical porous structure means that the formation angle α of a porous structure having an aspect ratio (D / L) of 2 or more and 1500 or less with respect to the horizontal surface of the counter electrode is in the range of 90 ° ± 10 ° which is vertical. That is formed.

  FIG. 1 is a schematic cross-sectional view showing an example of a nonconductive metal oxide layer having a vertical porous structure according to the present invention.

  In FIG. 1, a vertical porous structure 3 is formed on one electrode 1 of a counter electrode in a state substantially perpendicular to the electrode plane. The vertical porous structure 3 is constituted by the aperture 4 having an aspect ratio (D / L) of the depth D to the aperture width L of 2 or more and 1500 or less. A metal oxide layer 2 is formed. At this time, the angle α formed by the plane of the electrode 1 and the vertical porous structure 3 is preferably 90 ° ± 10 °.

  The method for forming a substantially vertical porous structure having an aspect ratio (D / L) of the depth D with respect to the opening width L according to the present invention of 30 or more and 2000 or less is not particularly limited. After forming a dispersion in which metal oxide fine particles and a dispersion solvent, a polymer compound, etc., are mixed using a known coating method such as a wet coating method, an ink jet method, a printing method, etc., photoelectrochemical etching A vertical porous structure can be formed by the method.

In the present invention, the photoelectrochemical etching method (also referred to as photoetching method) is a method in which a porous white scattering layer provided on an electrode is immersed in a solution and irradiated with light energy while an etching current is applied. For example, Journal of Electrochemical Society 134, pages 1038 to 1039 (1987) [J. Electrochem. Soc. Vol. 134 1038-1039 (1987)], R.M. L. Smith et al. (J. Appl. Phys., 71, R1, 1992), A.M. Lagoubi et al. (11th Photo-voltaic Solar Energy Conference, Montreux, 1992), 18th Solid-Surface Photochemistry Conference (announced on November 29, 1999), “Microstructure Control of TiO ₂ Surface by Photoelectrochemical Etching”, etc. Can be mentioned.

  As the material for forming the vertical porous structure according to the present invention, non-conductive metal oxide fine particles are used. Examples of the non-conductive metal oxide fine particles include titanium oxide, tin oxide, aluminum oxide, silicon oxide, zinc oxide, and magnesium oxide. However, it is not limited to these.

  From the viewpoint of securing the denseness of the nonconductive metal oxide layer according to the present invention and the shielding property of the transverse electric field, the average particle diameter of the nonconductive metal oxide fine particles is preferably 5 nm or more and 500 nm or less. Solvents that can be used in preparing the non-conductive metal oxide fine particle dispersion include water, toluene, xylene, ethanol, propanol, butanol, acetonitrile, acetylacetone, terpineol, butyl carbitol, butyl carbitol acetate, etc. Can be used.

In preparing the non-conductive metal oxide fine particle dispersion, a polymer compound can be used as a binder. The polymer compound that can be used is preferably one that does not substantially dissolve in the solvent constituting the electrolyte solution. Examples of the polymer compound applicable to the present invention include proteins such as gelatin and gelatin derivatives, cellulose derivatives, natural compounds such as starch, gum arabic, dextran, pullulan and carrageenan, and other natural compounds, polyvinyl alcohol, Examples thereof include synthetic polymer compounds such as polyethylene glycol, polyvinyl pyrrolidone, acrylamide polymers and derivatives thereof. As gelatin derivatives, acetylated gelatin, phthalated gelatin, polyvinyl alcohol derivatives as terminal alkyl group-modified polyvinyl alcohol, terminal mercapto group-modified polyvinyl alcohol, and cellulose derivatives include hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose and the like. It is done. Furthermore, Research Disclosure and those described in pages (71) to (75) of JP-A No. 64-13546, US Pat. No. 4,960,681, JP-A No. 62-245260, etc. superabsorbent polymers described, namely -COOM or -SO ₃ M (M is a hydrogen atom or an alkali metal) homopolymer or a vinyl monomer together or with other vinyl monomers of the vinyl monomer having a (e.g., sodium methacrylate, Copolymers with ammonium acid, potassium acrylate, etc.) are also used. Two or more of these binders can be used in combination.

  The method for drying the solvent of the non-conductive metal oxide fine particle dispersion applied on the electrode may be any method as long as the solvent can be evaporated. For example, heating from a heat source, a heating method using infrared light, a heating method using electromagnetic induction, and the like can be given. The evaporation may be performed under reduced pressure.

  In the display element of the present invention, it is desirable to perform a curing reaction of the polymer compound with a curing agent during or after coating and drying the nonconductive metal oxide fine particle dispersion.

  Examples of the hardener used in the present invention include, for example, U.S. Pat. No. 4,678,739, column 41, 4,791,042, JP-A-59-116655, and 62-245261. No. 61-18942, 61-249054, 61-245153, JP-A-4-218044, and the like. More specifically, aldehyde hardeners (formaldehyde, etc.), aziridine hardeners, epoxy hardeners, vinyl sulfone hardeners (N, N'-ethylene-bis (vinylsulfonylacetamide) Ethane, etc.), N-methylol hardeners (dimethylolurea, etc.), boric acid, metaboric acid or polymer hardeners (compounds described in JP-A-62-234157). When gelatin is used as the polymer compound, it is preferable to use a vinyl sulfone type hardener or a chlorotriazine type hardener alone or in combination. Moreover, when using polyvinyl alcohol, it is preferable to use boron-containing compounds such as boric acid and metaboric acid.

  These hardeners are used in an amount of 0.001 to 1 g, preferably 0.005 to 0.5 g, per 1 g of the polymer compound. In addition, it is possible to perform heat treatment and humidity adjustment during the curing reaction in order to increase the film strength.

  Further, in the display element of the present invention, after forming the nonconductive metal oxide layer according to the present invention, a firing treatment at a temperature of 120 ° C. or higher can form a stronger porous white scattering layer. Is preferable. Although the upper limit temperature cannot be defined unconditionally depending on the type of non-conductive metal oxide used, it is generally 300 ° C. or lower.

  In the non-conductive metal oxide layer according to the present invention, the shape of the opening to be formed is not particularly defined, but a circle, a regular triangle, a regular hexagon, or the like is preferably used. The opening width L is preferably 10 nm or more and 500 nm or less for the purpose of improving the resolution.

  In addition, it is further desirable that the apertures are arranged with two-dimensional periodicity from the viewpoint of the uniformity of the lateral electric field control. Two-dimensional periodicity means having periodic continuity in the plane direction.

  FIG. 2 is a schematic perspective view showing an example of an array of apertures having a two-dimensional periodicity of a non-conductive metal oxide layer according to the present invention.

  A nonconductive metal oxide layer 2 is formed on one electrode 1 of the counter electrode, and this nonconductive metal oxide layer 2 has a depth D with respect to the opening width L in the configuration as shown in FIG. The aperture portions 4 having an aspect ratio (D / L) of 2 or more and 1500 or less are formed in a regular arrangement on the plane.

  In the present invention, the aperture ratio, which is the area ratio of the aperture to the total area, is preferably 80% or more as the aperture ratio from the viewpoint of not deteriorating the density of the formed image and the brightness of the white background. Further, the thickness of the vertical porous structure 3 between the apertures 4 is preferably thin. However, the thickness is required to maintain the strength for maintaining the vertical porous structure 3, and the upper limit is 95% or less. It is preferable that However, the required thickness of the vertical porous structure 3 is appropriately selected according to the material used for the nonconductive metal oxide layer 2.

  When alumina oxide is used as the nonconductive metal oxide constituting the nonconductive metal oxide layer, a vertical porous structure can be easily obtained by an anodic oxidation method. Particularly preferred is an alumina nanohole array from which a high aspect ratio and a periodic pore structure can be easily obtained. As specific examples of producing the alumina nanohole array, methods disclosed in JP-A Nos. 2004-285405 and 7-86202 can be used.

(Porous white scattering layer)
In the present invention, a porous white scattering layer can be provided from the viewpoint of further enhancing display contrast and white display reflectance. In the porous white scattering layer according to the present invention, it is preferable to use fine particles having a larger average particle diameter as fine particles constituting the porous non-conductive metal oxide layer described above.

  The porous white scattering layer according to the present invention is preferably formed by applying a dispersion containing a metal oxide, a dispersion solvent, a fluorescent brightening agent and a polymer compound as main component particles by a coating method, an ink jet method, a printing method, or the like. Among them, it is preferable to form by applying a screen printing method.

  Examples of the main component particles constituting the porous white scattering layer according to the present invention include titanium oxide (anatase type or rutile type), barium sulfate, calcium carbonate, aluminum oxide, zinc oxide, magnesium oxide and zinc hydroxide, water, and the like. Magnesium oxide, magnesium phosphate, magnesium hydrogen phosphate, alkaline earth metal salt, talc, kaolin, zeolite, acid clay, glass, organic compounds such as polyethylene, polystyrene, acrylic resin, ionomer, ethylene-vinyl acetate copolymer resin, benzoguanamine A resin, urea-formalin resin, melamine-formalin resin, polyamide resin, or the like may be used alone or in combination, or in a state having voids that change the refractive index in the particles.

  Examples of the solvent used in the dispersion forming the porous white scattering layer according to the present invention include water, toluene, xylene, ethanol, propanol, butanol, acetonitrile, acetylacetone, terpineol, butyl carbitol, and butyl carbitol acetate. Can be used.

  Examples of the polymer compound applicable to the present invention include proteins such as gelatin and gelatin derivatives, cellulose derivatives, natural compounds such as starch, gum arabic, dextran, pullulan and carrageenan, and other natural compounds, polyvinyl alcohol, Examples include synthetic polymer compounds such as polyethylene glycol, polyvinyl pyrrolidone, acrylamide polymers, and derivatives thereof. As gelatin derivatives, acetylated gelatin, phthalated gelatin, polyvinyl alcohol derivatives as terminal alkyl group-modified polyvinyl alcohol, terminal mercapto group-modified polyvinyl alcohol, and cellulose derivatives include hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose and the like. It is done. Furthermore, Research Disclosure and those described in pages (71) to (75) of JP-A No. 64-13546, US Pat. No. 4,960,681, JP-A No. 62-245260, etc. Homopolymers of vinyl monomers having the described superabsorbent polymers, i.e. -COOM or -SO3M (M is a hydrogen atom or an alkali metal), or between these vinyl monomers or other vinyl monomers (e.g. sodium methacrylate, ammonium methacrylate) Copolymers with potassium acrylate, etc.) are also used. Two or more of these binders can be used in combination.

  The term “porous” as used in the present invention means that after the dispersion is applied onto an electrode and dried to form a porous white scattering material, silver or a compound containing silver in the chemical structure is contained on the scattering material. It refers to a penetrating state in which an electrolytic solution is applied and then sandwiched between counter electrodes, and a potential difference is applied between the counter electrodes to cause a dissolution and precipitation reaction of silver, and the ionic species can move between the electrodes.

  In the display element of the present invention, it is desirable that the polymer compound is cured with a curing agent during or after the dispersion is applied and dried. Examples of the hardener used in the present invention include the same compounds as the hardener used for curing the polymer compound applied to the non-conductive metal oxide layer, and the addition to the polymer compound The amount is similar.

  The porous white scattering layer according to the present invention may be formed at any position between the counter electrodes of the display element. However, the porous white scattering layer may be provided on the counter electrode surface, or the non-conductive metal oxide layer according to the present invention. It is preferable to form.

  FIG. 3 is a schematic cross-sectional view showing an example of the formation position of the porous white scattering layer in the display element of the present invention.

  In FIG. 3A, a nonconductive metal oxide layer 2 having a vertical porous structure 3 according to the present invention is formed on one electrode 1A between opposed electrodes, and is adjacent to the other electrode 1B. It has a porous white scattering layer 6 made of metal oxide 7. Moreover, the electrolyte solution 5 exists between the opposing electrodes. FIG. 3B shows an example in which the porous white scattering layer 6 is formed on the nonconductive metal oxide layer 2.

  As a method for applying the porous white scattering layer on each medium according to the present invention, for example, a coating method, a liquid spraying method, or a spraying method via a gas phase is used to fly a droplet using vibration of a piezoelectric element. For example, a piezo-type inkjet head, a bubble jet (registered trademark) -type inkjet head that uses a thermal head that uses bumping, and a spray method that sprays liquid using air pressure or hydraulic pressure. Is mentioned.

  The coating method can be appropriately selected from known coating methods. For example, an air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnation coater, reverse roller coater, transfer roller coater, curtain coater, double coater Examples include roller coaters, slide hopper coaters, gravure coaters, kiss roll coaters, bead coaters, cast coaters, spray coaters, calendar coaters, and extrusion coaters.

(Electrolyte solution)
Hereinafter, a preferable electrolyte solution for the display element of the present invention will be described.

(Electrolyte material)
In the display element of the present invention, the electrolyte solution can contain the following compounds. For example, KCl, KI, KBr, etc. as potassium compounds, LiBF ₄ , LiClO ₄ , LiPF ₆ , LiCF ₃ SO ₃ etc. as lithium compounds, tetraethylammonium perchlorate, tetrabutylammonium perchlorate, borofluoride as tetraalkylammonium compounds Examples include tetraethylammonium, tetrabutylammonium borofluoride, and tetrabutylammonium halide. Moreover, the molten salt electrolyte composition described in JP-A-2003-187881 paragraphs [0062] to [0081] can also be preferably used. Furthermore, a compound that becomes a redox pair such as I ⁻ / I ₃ ⁻ , Br ⁻ / Br ₃ ⁻ , and quinone / hydroquinone can be used.

(Silver or silver compound)
The silver or silver compound according to the present invention is silver or a compound containing silver in the chemical structure, such as silver oxide, silver sulfide, metallic silver, silver colloidal particles, silver halide, silver complex compound, silver ion, etc. It is a general term for compounds, and there are no particular limitations on the state species of the phase such as the solid state, the solubilized state in liquid and the gas state, and the charged state species such as neutral, anionic and cationic.

  The silver ion concentration contained in the electrolyte solution according to the present invention is preferably 0.2 mol / kg ≦ [Ag] ≦ 2.0 mol / kg. If the silver ion concentration is less than 0.2 mol / kg, it becomes a dilute silver solution, and the driving speed is delayed. If it is greater than 2 mol / kg, the solubility deteriorates, and precipitation tends to occur during low-temperature storage, which is disadvantageous. It is.

(Electrolyte additive)
In the display element of the present invention, the electrolyte is composed of at least one compound represented by the following general formula (1) or (2) and a compound represented by the following general formula (3) or general formula (4). It is preferable to contain at least one kind.

In the general formula (1), L represents an oxygen atom or CH ₂ , and R _{1 to} R ₄ each represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group, or an alkoxy group.

In the general formula (2), R ₅ and R ₆ each represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group or an alkoxy group.

General formula (3)
R ₇ -S-R ₈
In the general formula (3), R ₇ and R ₈ each represent a substituted or unsubstituted hydrocarbon group. However, when a ring containing an S atom is formed, an aromatic group is not taken.

In the general formula (4), M represents a hydrogen atom, a metal atom or quaternary ammonium. Z represents a nitrogen-containing heterocyclic ring. n represents an integer of 0 to 5, and R ₉ represents a halogen atom, an alkyl group, an aryl group, an alkylcarbonamide group, an arylcarbonamide group, an alkylsulfonamide group, an arylsulfonamide group, an alkoxy group, an aryloxy group, an alkylthio group. Group, arylthio group, alkylcarbamoyl group, arylcarbamoyl group, carbamoyl group, alkylsulfamoyl group, arylsulfamoyl group, sulfamoyl group, cyano group, alkylsulfonyl group, arylsulfonyl group, alkoxycarbonyl group, aryloxycarbonyl group Represents an alkylcarbonyl group, an arylcarbonyl group, an acyloxy group, a carboxyl group, a carbonyl group, a sulfonyl group, an amino group, a hydroxy group or a heterocyclic group, and when n is 2 or more, each R ₉ is the same. They may be different from each other or may be linked to each other to form a condensed ring.

  First, the compound represented by the general formula (1) will be described.

In the general formula (1), L represents an oxygen atom or CH ₂ , and R _{1 to} R ₄ each represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group, or an alkoxy group.

  Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, hexyl, octyl, dodecyl, tridecyl, tetradecyl, pentadecyl, and the like as aryl groups. Examples of the cycloalkyl group such as phenyl group, naphthyl group and the like include, for example, a cyclopentyl group, cyclohexyl group and the like, an alkoxyalkyl group, for example, a β-methoxyethyl group, a γ-methoxypropyl group and the like, as an alkoxy group, Examples thereof include a methoxy group, an ethoxy group, a propyloxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, and a dodecyloxy group.

  Hereinafter, although the specific example of a compound represented by General formula (1) is shown, in this invention, it is not limited only to these illustrated compounds.

  Next, the compound represented by the general formula (2) will be described.

In the general formula (2), R ₅ and R ₆ each represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group or an alkoxy group.

  Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, hexyl, octyl, dodecyl, tridecyl, tetradecyl, pentadecyl, and the like as aryl groups. Examples of the cycloalkyl group such as phenyl group, naphthyl group and the like include, for example, a cyclopentyl group, cyclohexyl group and the like, an alkoxyalkyl group, for example, a β-methoxyethyl group, a γ-methoxypropyl group and the like, as an alkoxy group, Examples thereof include a methoxy group, an ethoxy group, a propyloxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, and a dodecyloxy group.

  Hereinafter, although the specific example of a compound represented by General formula (2) is shown, in this invention, it is not limited only to these illustrated compounds.

  Among the compounds represented by the general formula (1) and the general formula (2) exemplified above, the exemplary compounds (1-1), (1-2), and (2-3) are particularly preferable.

  The compounds represented by the general formulas (1) and (2) are one kind of electrolyte solvents. However, in the display element of the present invention, another solvent is used in combination as long as the object effects of the present invention are not impaired. be able to. Specifically, tetramethylurea, sulfolane, dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone, 2- (N-methyl) -2-pyrrolidinone, hexamethylphosphortriamide, N-methylpropionamide, N, N-dimethylacetamide, N-methylacetamide, N, N dimethylformamide, N-methylformamide, butyronitrile, propionitrile, acetonitrile, acetylacetone, 4-methyl-2-pentanone, 2-butanol, 1-butanol, 2 -Propanol, 1-propanol, ethanol, methanol, acetic anhydride, ethyl acetate, ethyl propionate, dimethoxyethane, diethoxyfuran, tetrahydrofuran, ethylene glycol, diethylene glycol, triethylene glycol monobuty Ether, water and the like. Among these solvents, it is preferable to include at least one solvent having a freezing point of −20 ° C. or lower and a boiling point of 120 ° C. or higher.

  Furthermore, as a solvent which can be used in the present invention, J.P. A. Riddick, W.M. B. Bunger, T.A. K. Sakano, “Organic Solvents”, 4th ed. , John Wiley & Sons (1986). Marcus, “Ion Solvation”, John Wiley & Sons (1985), C.I. Reichardt, “Solvents and Solvent Effects in Chemistry”, 2nd ed. VCH (1988), G .; J. et al. Janz, R.A. P. T.A. Tomkins, “Nonqueous Electronics Handbook”, Vol. 1, Academic Press (1972).

  In the present invention, the electrolyte solvent may be a single type or a mixture of solvents, but a mixed solvent containing ethylene carbonate is preferred. The addition amount of ethylene carbonate is preferably 10% by mass or more and 90% by mass or less of the total electrolyte solvent mass. A particularly preferable electrolyte solvent is a mixed solvent having a mass ratio of propylene carbonate / ethylene carbonate of 7/3 to 3/7. When the propylene carbonate ratio is larger than 7/3, the ionic conductivity is inferior and the response speed is lowered. When the propylene carbonate ratio is smaller than 3/7, the electrolyte tends to be deposited at a low temperature.

  In the display element of the present invention, it is preferable to use the compound represented by the general formula (3) or (4) together with the compound represented by the general formula (1) or (2).

In the general formula (3), R ₇ and R ₈ each represent a substituted or unsubstituted hydrocarbon group, and these include a linear group or a branched group. Further, these hydrocarbon groups may contain one or more nitrogen atoms, oxygen atoms, phosphorus atoms, sulfur atoms, and halogen atoms. However, when a ring containing an S atom is formed, an aromatic group is not taken.

  Examples of groups that can be substituted for the hydrocarbon group include amino groups, guanidino groups, quaternary ammonium groups, hydroxyl groups, halogen compounds, carboxylic acid groups, carboxylate groups, amide groups, sulfinic acid groups, sulfonic acid groups, and sulfates. Groups, phosphonic acid groups, phosphate groups, nitro groups, cyano groups and the like.

  Generally, in order to cause dissolution and precipitation of silver, it is necessary to solubilize silver in an electrolyte. For example, solubilize silver or a compound containing silver by coexisting with a compound containing a chemical structural species that interacts with silver, such as a coordinate bond with silver or a weak covalent bond with silver. It is common to use a means for converting to an object. As the chemical structural species, halogen atoms, mercapto groups, carboxyl groups, imino groups and the like are known, but in the present invention, the thioether group is also useful as a silver solvent and has little influence on the coexisting compound, It is characterized by high solubility in solvents.

  Hereinafter, although the specific example of a compound represented by General formula (3) is shown, in this invention, it is not limited only to these illustrated compounds.

3-1: CH ₃ SCH ₂ CH ₂ OH
3-2: HOCH ₂ CH ₂ SCH ₂ CH ₂ OH
3-3: HOCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OH
3-4: HOCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OH
3-5: HOCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ OH
3-6: HOCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OH
3-7: H ₃ CSCH ₂ CH ₂ COOH
3-8: HOOCCH ₂ SCH ₂ COOH
3-9: HOOCCH ₂ CH ₂ SCH ₂ CH ₂ COOH
3-10: HOOCCH ₂ SCH ₂ CH ₂ SCH ₂ COOH
3-11: HOOCCH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ COOH
3-12: HOOCCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH (OH) CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ COOH
_{3-13: HOOCCH 2 CH 2 SCH 2} CH 2 SCH 2 CH (OH) CH (OH) CH 2 SCH 2 CH 2 SCH 2 CH 2 COOH
3-14: H ₃ CSCH ₂ CH ₂ CH ₂ NH ₂
3-15: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ NH ₂
3-16: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NH ₂
3-17: H ₃ CSCH ₂ CH ₂ CH (NH ₂ ) COOH
3-18: H ₂ NCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂
NH ₂
3-19: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂
NH ₂
3-20: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂
NH ₂
3-21: HOOC (NH ₂ ) CHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ CH (NH ₂ ) COOH
3-22: HOOC (NH ₂ ) CHCH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH (NH ₂ ) COOH
3-23: HOOC (NH ₂ ) CHCH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH (NH ₂ ) COOH
3-24: H ₂ N (═O) CCH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ C (═O) NH ₂
3-25: H ₂ N (O =) CCH ₂ SCH ₂ CH ₂ SCH ₂ C (O =) NH _{2
3-26: H 2 NHN (O =} ) CCH 2 SCH 2 CH 2 SCH 2 C (= O) NHNH 2
3-27: H ₃ C (O =) NHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NHC (O =) CH ₃
3-28: H ₂ NO ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SO ₂ NH ₂
3-29: NaO ₃ SCH ₂ CH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ CH ₂ SO ₃ Na
3-30: H ₃ CSO ₂ NHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NHO ₂ SCH ₃
3-31: H ₂ N (NH) CSCH ₂ CH ₂ SC (NH) NH ₂ .2HBr
3-32: H ₂ N (NH) CSCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SC (NH) NH ₂ .2HCl
3-33: H ₂ N (NH) CNHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NHC (NH) NH ₂ .2HBr
3-34: [(CH ₃ ) ₃ NCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ N (CH ₃ ) ₃ ] 2 ⁺ · 2Cl ⁻

  Among the above-exemplified compounds, Exemplified Compound 3-2 is particularly preferable from the viewpoint that the object and effects of the present invention can be exhibited.

  Next, the compound represented by formula (4) will be described.

In the general formula (4), M represents a hydrogen atom, a metal atom, or quaternary ammonium. Z represents a nitrogen-containing heterocyclic ring. n represents an integer of 0 to 5, and R ₉ represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkylcarbonamide group, an arylcarbonamide group, an alkylsulfonamide group, an arylsulfonamide group, an alkoxy group, an aryloxy group Group, alkylthio group, arylthio group, alkylcarbamoyl group, arylcarbamoyl group, carbamoyl group, alkylsulfamoyl group, arylsulfamoyl group, sulfamoyl group, cyano group, alkylsulfonyl group, arylsulfonyl group, alkoxycarbonyl group, aryl Represents an oxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group, an acyloxy group, a carboxyl group, a carbonyl group, a sulfonyl group, an amino group, a hydroxy group or a heterocyclic group, and when n is 2 or more, each R ₉ is They may be the same or different, and may be linked together to form a condensed ring.

Examples of the metal atom represented by M in the general formula (4) include Li, Na, K, Mg, Ca, Zn, and Ag. Examples of the quaternary ammonium include NH ₄ , N (CH ₃ ) ₄ , N (C ₄ H ₉ ) ₄ , N (CH ₃ ) ₃ C ₁₂ H ₂₅ , N (CH ₃ ) ₃ C ₁₆ H ₃₃ , N (CH ₃ ) ₃ CH ₂ C ₆ H _{5 and the} like It is done.

  Examples of the nitrogen-containing heterocycle represented by Z in the general formula (4) include a tetrazole ring, a triazole ring, an imidazole ring, an oxadiazole ring, a thiadiazole ring, an indole ring, an oxazole ring, a benzoxazole ring, and a benzimidazole ring. Benzothiazole ring, benzoselenazole ring, naphthoxazole ring and the like.

Examples of the halogen atom represented by R ₉ in the general formula (4) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group include methyl, ethyl, propyl, i- Examples include propyl, butyl, t-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, octyl, dodecyl, hydroxyethyl, methoxyethyl, trifluoromethyl, benzyl, etc. Examples of the aryl group include phenyl, naphthyl and the like. Examples of the alkylcarbonamide group include acetylamino, propionylamino, butyroylamino and the like. Examples of the arylcarbonamide group include benzoylamino and the like. Examples of the sulfonamide group include methanesulfonyl. Minosulfonyl, ethanesulfonylamino group and the like, arylsulfonamide groups include, for example, benzenesulfonylamino group, toluenesulfonylamino group and the like, and aryloxy groups include, for example, phenoxy and the like, alkylthio Examples of the group include each group such as methylthio, ethylthio, and butylthio. Examples of the arylthio group include phenylthio group and tolylthio group. Examples of the alkylcarbamoyl group include methylcarbamoyl, dimethylcarbamoyl, Examples include ethyl carbamoyl, diethyl carbamoyl, dibutyl carbamoyl, piperidyl carbamoyl, morpholyl carbamoyl and the like, and aryl carbamoyl groups include, for example, phenyl carbamoyl, methyl phenyl carbamoyl Examples include groups such as vamoyl, ethylphenylcarbamoyl, and benzylphenylcarbamoyl. Examples of the alkylsulfamoyl group include methylsulfamoyl, dimethylsulfamoyl, ethylsulfamoyl, diethylsulfamoyl, and dibutylsulfamoyl. Examples of each group include moyl, piperidylsulfamoyl, morpholylsulfamoyl, and arylsulfamoyl groups include, for example, phenylsulfamoyl, methylphenylsulfamoyl, ethylphenylsulfamoyl, benzylphenylsulfamoyl. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group. Examples of the arylsulfonyl group include phenylsulfonyl and 4-chlorophenylsulfonyl. Examples of each group include p-toluenesulfonyl and the like. Examples of the alkoxycarbonyl group include groups such as methoxycarbonyl, ethoxycarbonyl and butoxycarbonyl. Examples of the aryloxycarbonyl group include phenoxycarbonyl and the like. Examples of the alkylcarbonyl group include acetyl, propionyl, butyroyl, and the like. Examples of the arylcarbonyl group include a benzoyl group and an alkylbenzoyl group. Examples of the acyloxy group include acetyloxy. , Propionyloxy, butyroyloxy and the like, and examples of the heterocyclic group include oxazole ring, thiazole ring, triazole ring, selenazole ring, tetrazole ring, oxadiazole ring, thiadiazole ring, thiazol ring, and the like. Down ring, a triazine ring, a benzoxazole ring, benzothiazole ring, an indolenine ring, benzimidazole benzoselenazole ring, naphthothiazole ring, triazaindolizine ring, diaza indolizine ring, tetraazacyclododecane indolizine ring group, and the like. These substituents further include those having a substituent.

  Next, although the preferable specific example of a compound represented by General formula (4) is shown, this invention is not limited to these compounds.

  Among the above-exemplified compounds, Exemplified Compounds 4-12 and 4-18 are particularly preferable from the viewpoint that the object and effects of the present invention can be exhibited.

(Halogen ion, silver ion concentration ratio)
In the display element of the present invention, the molar concentration of halogen ions or halogen atoms contained in the electrolyte is [X] (mol / kg), and silver contained in the electrolyte or the total silver of the compound containing silver in the chemical structure. When the molar concentration is [Ag] (mol / kg), it is preferable to satisfy the condition defined by the following formula (1).

Formula (1)
0 ≦ [X] / [Ag] ≦ 0.01
The halogen atom as used in the field of this invention means an iodine atom, a chlorine atom, a bromine atom, and a fluorine atom. When [X] / [Ag] is larger than 0.01, X ⁻ → X ₂ is generated during the redox reaction of silver, and X ₂ easily cross-oxidizes with blackened silver to dissolve blackened silver. Therefore, the molar concentration of halogen atoms is preferably as low as possible relative to the molar concentration of silver. In the present invention, 0 ≦ [X] / [Ag] ≦ 0.001 is more preferable. In the case of adding halogen ions, the halogen species preferably have a total molar concentration of [I] <[Br] <[Cl] <[F] from the viewpoint of improving memory properties.

(Other additives)
Examples of the constituent layers of the display element of the present invention include auxiliary layers such as a protective layer, a filter layer, an antihalation layer, a crossover light cut layer, and a backing layer. Sensitizer, noble metal sensitizer, photosensitive dye, supersensitizer, coupler, high boiling point solvent, antifoggant, stabilizer, development inhibitor, bleach accelerator, fixing accelerator, color mixing inhibitor, formalin scavenger, Toning agents, hardeners, surfactants, thickeners, plasticizers, slip agents, UV absorbers, anti-irradiation dyes, filter light absorbing dyes, anti-bacterial agents, polymer latex, heavy metals, antistatic agents, matting agents Etc. can be contained as required.

  More specifically, these additives described above are described in detail in Research Disclosure (hereinafter abbreviated as RD), Volume 176 Item / 17643 (December 1978), Volume 184, Item / 18431 (August 1979), Volume 187. Item / 18716 (November 1979) and Volume 308 Item / 308119 (December 1989).

  The types of compounds and their descriptions shown in these three research disclosures are listed below.

Additive RD17643 RD18716 RD308119
Page Classification Page Classification Page Classification Chemical sensitizer 23 III 648 Upper right 96 III
Sensitizing dye 23 IV 648-649 996-8 IV
Desensitizing dye 23 IV 998 IV
Dye 25-26 VIII 649-650 1003 VIII
Development accelerator 29 XXI 648 Upper right Anti-fogging agent / stabilizer
24 IV 649 Upper right 1006-7 VI
Brightener 24 V 998 V
Hardener 26 X 651 Left 1004-5 X
Surfactant 26-7 XI 650 Right 1005-6 XI
Antistatic agent 27 XII 650 Right 1006-7 XIII
Plasticizer 27 XII 650 Right 1006 XII
Slipper 27 XII
Matting agent 28 XVI 650 Right 1008-9 XVI
Binder 26 XXII 1003-4 IX
Support 28 XVII 1009 XVII
〔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. RDNo. 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.

〔electrode〕
In the display element of the present invention, it is preferable that at least one of the counter electrodes is a metal electrode. As the metal electrode, for example, known metal species such as platinum, gold, silver, copper, aluminum, zinc, nickel, titanium, bismuth, and alloys thereof can be used. The metal electrode is preferably a metal having a work function close to the redox potential of silver in the electrolyte. Above all, silver or a silver electrode having a silver content of 80% or more is advantageous for maintaining the reduced state of silver. Excellent in preventing dirt. As an electrode manufacturing method, an existing method such as an evaporation method, a printing method, an ink jet method, a spin coating method, or a CVD method can be used.

  In the display element of the present invention, it is preferable that at least one of the counter electrodes is a transparent electrode. The transparent electrode is not particularly limited as long as it is transparent and conducts electricity. For example, Indium Tin Oxide (ITO: Indium Tin Oxide), Indium Zinc Oxide (IZO: Indium Zinc Oxide), Fluorine Doped Tin Oxide (FTO), Indium Oxide, Zinc Oxide, Platinum, Gold, Silver, Rhodium, Copper, Examples thereof include chromium, carbon, aluminum, silicon, amorphous silicon, and BSO (Bismuth Silicon Oxide). In order to form the electrode in this manner, for example, an ITO film may be vapor-deposited on the substrate by a sputtering method or the like, or an ITO film may be formed on the entire surface and then patterned by a photolithography method. The surface resistance value is preferably 100Ω / □ or less, and more preferably 10Ω / □ or less. The thickness of the transparent electrode is not particularly limited, but is generally 0.1 to 20 μm.

〔Layer structure〕
The constituent layers between the counter electrodes of the display element of the present invention will be further described.

As a constituent layer according to the display element of the present invention, a constituent layer containing a hole transport material can be provided. Examples of hole transport materials include aromatic amines, triphenylene derivatives, oligothiophene compounds, polypyrroles, polyacetylene derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polythiophene derivatives, polyaniline derivatives, polytoluidine derivatives, CuI, CuSCN CuInSe ₂ , Cu (In, Ga) Se, CuGaSe ₂ , Cu ₂ O, CuS, CuGaS ₂ , CuInS ₂ , CuAlSe ₂ , GaP, NiO, CoO, FeO, Bi ₂ O ₃ , MoO ₂ , Cr ₂ O ₃ Etc.

[Other components of the display element]
In the display element of the present invention, a sealant, a columnar structure, and spacer particles can be used as necessary.

  Sealing agent is for sealing so that it does not leak out. It is also called sealing agent. Epoxy resin, urethane resin, acrylic resin, vinyl acetate resin, ene-thiol resin, silicone resin, modified resin A curing type such as a polymer resin, such as a thermosetting type, a photocurable type, a moisture curable type, and an anaerobic curable type can be used.

  The columnar structure provides strong self-holding (strength) between the substrates, for example, a columnar body, a quadrangular columnar body, an elliptical columnar body, a trapezoidal array arranged in a predetermined pattern such as a lattice arrangement. A columnar structure such as a columnar body can be given. Alternatively, stripes arranged at predetermined intervals may be used. This columnar structure is not a random array, but can be properly maintained at intervals of the substrate, such as an evenly spaced array, an array in which the interval gradually changes, and an array in which a predetermined arrangement pattern is repeated at a constant period. The arrangement is preferably considered so as not to disturb the display. If the ratio of the area occupied by the columnar structure in the display area of the display element is 1 to 40%, a practically sufficient strength as a display element can be obtained.

  A spacer may be provided between the pair of substrates for uniformly maintaining a gap between the substrates. Examples of the spacer include a sphere made of resin or inorganic oxide. Further, a fixed spacer having a surface coated with a thermoplastic resin is also preferably used. In order to hold the gap between the substrates uniformly, only the columnar structure may be provided, but both the spacer and the columnar structure may be provided, or instead of the columnar structure, only the spacer is used as the space holding member. May be used. The diameter of the spacer is equal to or less than the height of the columnar structure, preferably equal to the height. When the columnar structure is not formed, the diameter of the spacer corresponds to the thickness of the cell gap.

[Screen printing]
In the present invention, a sealant, a columnar structure, an electrode pattern, and the like can be formed by a screen printing method. In the screen printing method, a screen on which a predetermined pattern is formed is placed on an electrode surface of a substrate, and a printing material (a composition for forming a columnar structure, such as a photocurable resin) is placed on the screen. Then, the squeegee is moved at a predetermined pressure, angle, and speed. Thereby, the printing material is transferred onto the substrate through the pattern of the screen. Next, the transferred material is heat-cured and dried. When the columnar structure is formed by the screen printing method, the resin material is not limited to a photocurable resin, and for example, a thermosetting resin such as an epoxy resin or an acrylic resin or a thermoplastic resin can also be used. As thermoplastic resins, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl acetate resin, polymethacrylate resin, polyacrylate resin, polystyrene resin, polyamide resin, polyethylene resin, polypropylene resin, fluororesin, polyurethane resin , Polyacrylonitrile resin, polyvinyl ether resin, polyvinyl ketone resin, polyether resin, polyvinyl pyrrolidone resin, saturated polyester resin, polycarbonate resin, chlorinated polyether resin and the like. The resin material is preferably used in the form of a paste by dissolving the resin in an appropriate solvent.

  After the columnar structure or the like is formed on the substrate as described above, a spacer is provided on at least one of the substrates as desired, and the pair of substrates are overlapped with the electrode formation surfaces facing each other to form an empty cell. . A superposed pair of substrates is heated while being pressed from both sides, and bonded to obtain a display cell. If the electrolyte solution is vacuum-injected into the display cell, the display element of the present invention can be obtained.

[Driving method of display element]
In the display element of the present invention, it is preferable to perform a driving operation in which silver black is precipitated by applying a voltage equal to or higher than the precipitation overvoltage and silver black is continuously precipitated by applying a voltage lower than the precipitation overvoltage. By performing this driving operation, the writing energy can be reduced, the driving circuit load can be reduced, and the writing speed as a screen can be improved. It is generally known that overvoltage exists in electrode reactions in the electrochemical field. For example, overvoltage is described in detail on page 121 of “Introduction to Chemistry of Electron Transfer—Introduction to Electrochemistry” (published by Asakura Shoten in 1996). Since the display element of the present invention can also be regarded as an electrode reaction between the electrode and silver in the electrolyte, it can be easily understood that overvoltage exists even in silver dissolution precipitation. Since the magnitude of the overvoltage is governed by the exchange current density, it is possible to continue silver black precipitation by applying a voltage equal to or lower than the precipitation overvoltage after the formation of silver black as in the present invention. However, it is presumed that electron injection can be easily performed with little excess electric energy.

  The driving operation of the display element of the present invention may be simple matrix driving or active matrix driving. 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 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 merits such as gradation and memory function. For example, a circuit described in FIG. 5 of JP-A-2004-29327 can be used.

[Product application]
The display element of the present invention can be used in an electronic book field, an ID card field, a public field, a traffic field, a broadcast field, a payment field, a distribution logistics field, 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, Cash cards, credit cards, highway cards, driver's licenses, hospital examination cards, electronic medical records, health insurance cards, Basic Resident Registers, passports, electronic books, etc.

  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.

<< Production of each component material >>
[Production of electrodes]
(Production of electrode 1)
An ITO film having a pitch of 145 μm and an electrode width of 130 μm was formed on a glass substrate having a thickness of 1.5 mm and a size of 2 cm × 4 cm to obtain a transparent electrode (electrode 1).

(Preparation of electrode 2)
A silver-palladium electrode (electrode 2) having an electrode thickness of 0.8 μm, a pitch of 145 μm, and an electrode interval of 130 μm is formed on a glass substrate having a thickness of 1.5 mm and a size of 2 cm × 4 cm by using a known method. Got.

[Forming member of non-conductive metal oxide layer]
(Preparation of forming dispersion)
<Preparation of Dispersion 1>
Dispersion 1 was obtained by adding 20% by mass of titanium oxide particles having an average particle diameter of 20 nm to an aqueous solution containing 2% by mass of polyvinyl alcohol (average molecular weight 30000) and dispersing with an ultrasonic disperser.

<Preparation of Dispersion 2>
Dispersion 2 was obtained by adding 20% by mass of aluminum oxide particles having an average particle diameter of 30 nm to an aqueous solution containing 2% by mass of polyvinyl alcohol (average molecular weight 30000) and dispersing with an ultrasonic disperser.

<Preparation of Dispersion 3>
Dispersion 3 was obtained by adding 20% by mass of zinc oxide particles having an average particle diameter of 34 nm to an aqueous solution containing 2% by mass of polyvinyl alcohol (average molecular weight 30000) and dispersing with an ultrasonic disperser.

(Formation of non-conductive metal oxide layer)
<Formation of Nonconductive Metal Oxide Layer 1 Having Vertical Porous Structure>
Dispersion 1 was screen-printed on electrode 1 such that the average dry film thickness was 10 μm, and then dried at 50 ° C. for 30 minutes and then at 85 ° C. for 1 hour to obtain a titanium oxide film.

This titanium oxide film is subjected to an optical etching amount of 10 C / cm ² at an angle of 90 degrees with respect to the electrode 1 using an ultrahigh pressure mercury lamp at anodic polarization in an acidic aqueous solution +1.0 V (vs SCE). To form a nonconductive metal oxide layer 1 having a vertical porous structure with a vertical porous structure having an angle of 92 degrees, an opening width L of 102 nm, an aspect ratio (D / L) of 98, and an opening ratio of 82%. did.

<Formation of non-conductive metal oxide layer 2 having a vertical porous structure>
Dispersion 2 was screen-printed on electrode 1 such that the average dry film thickness was 20 μm, and then dried at 50 ° C. for 30 minutes and then at 85 ° C. for 1 hour to obtain an aluminum oxide film. Thereafter, the same processing as the formation of the nonconductive metal oxide layer 1 is performed, and the angle of the vertical porous structure is 89 degrees, the opening width L is 32 nm, the aspect ratio (D / L) is 625, and the opening ratio is 64%. A nonconductive metal oxide layer 2 having a vertical porous structure was formed.

<Formation of Nonconductive Metal Oxide Layer 3 Having Vertical Porous Structure>
Dispersion 3 was screen-printed on electrode 1 so that the average dry film thickness was 20 μm, and then dried at 50 ° C. for 30 minutes and then at 85 ° C. for 1 hour to obtain a zinc oxide film. Thereafter, the same process as the formation of the nonconductive metal oxide layer 1 is performed, and the angle of the vertical porous structure is 91 degrees, the opening width L is 150 nm, the aspect ratio (D / L) is 133, and the opening ratio is 82%. A nonconductive metal oxide layer 3 having a vertical porous structure was formed.

<Formation of Nonconductive Metal Oxide Layer 4 Having Vertical Porous Structure>
An aluminum film was deposited on the electrode 2 to a thickness of 500 nm. A fine concavo-convex pattern was transferred onto the surface of the aluminum plate using a SiC mold having a protrusion period of 100 nm. Subsequently, 0.05 mol / L oxalic acid was used, anodized in a warm bath of 16 ° C. and 50 V, washed with pure water and isopropyl alcohol, and a nonconductive metal oxide layer 4 made of porous alumina was formed. The nonconductive metal oxide layer 4 has a vertical porous structure angle of 90 degrees, an opening width L of 92 nm, an aspect ratio (D / L) of 5.4, and an opening ratio of 84%.

(Preparation of dispersion for forming porous white scattering layer)
(Preparation of porous white scattering layer dispersion 1)
In an aqueous solution containing 2% by mass of polyvinyl alcohol (average molecular weight 30000), 20% by mass of zinc oxide particles having an average particle size of 30 nm was added and dispersed with an ultrasonic disperser to obtain a porous white scattering layer dispersion 1.

(Preparation of porous white scattering layer dispersion 2)
In an aqueous solution containing 2% by mass of polyvinyl alcohol (average molecular weight 30000), 20% by mass of titanium oxide particles having an average particle diameter of 250 nm was added and dispersed with an ultrasonic disperser to obtain a porous white scattering layer dispersion 2.

(Preparation of electrolyte solution)
(Preparation of electrolyte 1)
In 2.5 g of dimethyl sulfoxide, 90 mg of sodium iodide and 75 mg of silver iodide were added and completely dissolved, and then 150 mg of polyvinylpyrrolidone (average molecular weight 15000) was added and stirred for 1 hour while heating to 120 ° C. Liquid 1 was obtained.

<< Production of display element >>
(Preparation of display element 1)
The porous white scattering layer dispersion 2 is applied on the electrode 2 by screen printing so that the film thickness after drying is 20 μm, dried at 50 ° C. for 30 minutes, and then dried at 250 ° C. for 1 hour to make porous. A white-white scattering layer 2 was formed.

  The electrode 2 and the electrode 1 were opposed to each other, adhered with an epoxy sealant, and an empty cell was produced by heating and pressing. The electrolyte solution was vacuum-injected into the empty cell, and the injection port was sealed with an epoxy-based ultraviolet curable resin to produce the display element 1.

(Preparation of display element 2)
A display element 2 having the configuration shown in FIG.

  On the electrode 2 (electrode 1B in FIG. 3), the porous white scattering layer dispersion 2 was applied by screen printing so that the film thickness after drying was 20 μm, dried at 50 ° C. for 30 minutes, and then 250 ° C. And dried for 1 hour to form a porous white scattering layer 2. Subsequently, it was made to oppose with the nonelectroconductive metal oxide layer 1 provided on the electrode 1 (electrode 1A of FIG. 3), it adhere | attached with the epoxy-type sealing agent, and the empty cell was produced by the heat press. The electrolyte solution was vacuum-injected into the empty cell, and the injection port was sealed with an epoxy-based ultraviolet curable resin to produce the display element 2.

(Production of display elements 3 to 5)
In the production of the display element 2, the display is performed in the same manner except that the nonconductive metal oxide layer 1 provided on the electrode 1 (electrode 1A in FIG. 3) is changed to the nonconductive metal oxide layers 2 to 4, respectively. Elements 3 to 5 were produced.

(Preparation of display element 6)
In the production of the display element 5, the display element 6 was produced in the same manner except that the porous white scattering layer dispersion 1 was used instead of the porous white scattering layer dispersion 2. did.

(Preparation of display element 7)
After the nonconductive metal oxide layer 4 is formed on the electrode 1 (electrode 1A in FIG. 3), the porous white scattering layer is dispersed on the nonconductive metal oxide layer 4 as shown in FIG. The product 1 was applied by screen printing so that the film thickness after drying was 20 μm, dried at 50 ° C. for 30 minutes, and then dried at 250 ° C. for 1 hour to form a porous white scattering layer 1.

  This was made to face the electrode 2 (electrode 1B in FIG. 3) so as to have the configuration shown in FIG. 3B, adhered with an epoxy-based sealant, and an empty cell was produced by heating and pressing. Next, an electrolyte solution was vacuum-injected into the empty cell, and the injection port was sealed with an epoxy-based ultraviolet curable resin, whereby a display element 7 was produced.

(Display element 8)
In the production of the display element 2, a dispersion 2 (a dispersion containing aluminum oxide particles having an average particle size of 30 nm) is screened on the electrode 1 (electrode 1A in FIG. 3) so that the average dry film thickness is 20 μm. It was printed and then dried at 50 ° C. for 30 minutes and subsequently at 85 ° C. for 1 hour to obtain an aluminum oxide layer. Thereafter, the aluminum oxide layer is photoetched under the conditions that the vertical porous structure has an angle of 89 degrees, the opening width L is 13 nm, the aspect ratio (D / L) is 1538, and the opening ratio is 42%. Layer 5 was formed.

  Subsequently, it was made to oppose with the nonelectroconductive metal oxide layer 1 provided on the electrode 1 (electrode 1A of FIG. 3), it adhere | attached with the epoxy-type sealing agent, and the empty cell was produced by the heat press. The electrolyte solution was vacuum-injected into the empty cell, and the injection port was sealed with an epoxy-based ultraviolet curable resin, whereby the display element 8 was produced.

(Display element 9)
A display element 9 having the configuration described in FIG. 4 was produced.

  20% by mass of titanium oxide particles having an average particle diameter of 30 nm was added to the electrolytic solution 1, and the mixture was stirred with an ultrasonic dispersing device to obtain an electrolytic solution 2. Next, a wall having the same height as the non-conductive metal oxide film was provided around the non-conductive metal oxide layer 4 provided on the electrode 1 with an epoxy sealant, and this was filled with the electrolytic solution 2. On top of this, the electrode 2 was placed so that the electrode surface was on the inside, adhered, and the sealant was cured, whereby the display element 9 was produced. The non-conductive metal oxide layer 4 has two electrodes facing each other with a vertical porous structure angle of 90 degrees, an aperture width L of 92 nm, an aspect ratio (D / L) of 5.4, and an aperture ratio of 84%. Each is in contact with each other.

<< Evaluation of display element >>
About each produced said display element, the measurement of the characteristic value and performance evaluation were performed in accordance with the following method.

(Measurement of aspect ratio of aperture, angle of porous structure, aperture ratio)
With an electron microscope VE-9800 manufactured by Keyence Co., Ltd., images of five arbitrary surfaces of the nonconductive metal oxide layer were taken, and the opening width L and the opening ratio were measured. In addition, the non-conductive metal oxide layer is ion-etched by a focused ion beam processing method, a cross-sectional image is taken, the angle between the center line of the aperture and the electrode surface is measured at 10 points, and the average is calculated. The angle of the porous structure was determined.

(Evaluation of display element: Evaluation of display speed)
A voltage of 1.5 V is applied to each of the display devices prepared above for 3 seconds to display white, then a voltage of −1.5 V is applied for 0.5 seconds to display gray, and a reflectance at 550 nm. Was measured with a spectrocolorimeter CM-3700d manufactured by Konica Minolta Sensing. The measured reflectance was _RGlay, and _RGlay was used as an indicator of display speed. Here, it is assumed that the display speed is higher as R _Glay is lower.

(Evaluation of display element: Evaluation of display unevenness resistance)
A voltage of 1.5 V is applied to each of the display devices prepared above for 3 seconds to display white, then a voltage of −1.5 V is applied for 0.5 seconds to display gray, and any display element can be displayed. The reflectance at 550 nm at two locations was measured with a spectrocolorimeter CM-3700d manufactured by Konica Minolta Sensing Co., and the difference in reflectance was calculated. The calculated difference in reflectance was _ΔRGlay, and _RGlay was used as an indicator of display unevenness resistance. Here, it is assumed that the smaller the ΔR _Glay is, the less display unevenness is.

  The results obtained as described above are shown in Table 1.

  As is apparent from the results shown in Table 1, the display element of the present invention provided with the nonconductive metal oxide layer having the vertical porous structure defined in the present invention has a higher display speed and display unevenness resistance than the comparative example. It turns out that it is excellent. This is because the electrolyte solution fills the pores of the non-conductive metal oxide layer having a vertical porous structure, and the ionic compound or additive is adsorbed on the wall of the metal oxide layer, thereby causing reaction rate and display unevenness. It is estimated that resistance has improved.

It is a schematic sectional drawing which shows an example of the nonelectroconductive metal oxide layer which has the vertical porous structure based on this invention. It is a schematic perspective view which shows an example of the opening part arrangement | sequence which has a two-dimensional periodicity of the nonelectroconductive metal oxide layer which concerns on this invention. It is a schematic sectional drawing which shows an example of the formation position of the porous white scattering layer in the display element of this invention. It is an example of the display element used as a comparison with the display element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A, 1B Electrode 2 Nonelectroconductive metal oxide layer 3 Vertical porous structure 4 Opening part 5 Electrolyte liquid 6 Porous white scattering layer 7 Metal oxide L Opening width of an opening part D Depth of an opening part

Claims (8)

Electrochemical display that has an electrolyte containing silver or a compound containing silver in the chemical structure between the counter electrodes, and generates a potential difference between the counter electrodes to cause dissolution and precipitation of silver and display an image. A non-conductive metal oxide having a substantially vertical porous structure, wherein the aspect ratio (D / L) of the depth D to the opening width L is 2 or more and 1500 or less on one electrode of the counter electrode A display element, wherein a layer is formed, and the nonconductive metal oxide layer is not in direct contact with at least one electrode of the counter electrode or a substrate holding the electrode. The display element according to claim 1, wherein the opening width L is 10 nm or more and 300 nm or less. The display element according to claim 1, wherein the apertures of the substantially vertical porous structure are an array having a two-dimensional periodicity. The display element according to claim 3, wherein the aperture ratio of the aperture is 80% or more. The display element according to claim 1, wherein the nonconductive metal oxide layer is an alumina oxide layer. The display element according to claim 1, further comprising a porous white scattering layer between the nonconductive metal oxide layer and the counter electrode. The display element according to claim 6, wherein the porous white scattering layer is a titanium oxide nanoporous layer. The electrolyte does not substantially contain iodine ions, and at least one of the compounds represented by the following general formula (1) or (2) and at least one of the compounds represented by the following general formula (3) or (4) The display element according to claim 1, comprising one kind.

[Wherein, L represents an oxygen atom or CH ₂ , and R _{1 to} R ₄ each represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group, or an alkoxy group. ]

[Wherein, R ₅ and R ₆ each represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group or an alkoxy group. ]
General formula (3)
R ₇ -S-R ₈
[Wherein R ₇ and R ₈ each represents a substituted or unsubstituted hydrocarbon group. However, when a ring containing an S atom is formed, an aromatic group is not taken. ]

[Wherein, M represents a hydrogen atom, a metal atom or quaternary ammonium. Z represents a nitrogen-containing heterocyclic ring. n represents an integer of 0 to 5, and R ₉ represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkylcarbonamide group, an arylcarbonamide group, an alkylsulfonamide group, an arylsulfonamide group, an alkoxy group, an aryloxy group Group, alkylthio group, arylthio group, alkylcarbamoyl group, arylcarbamoyl group, carbamoyl group, alkylsulfamoyl group, arylsulfamoyl group, sulfamoyl group, cyano group, alkylsulfonyl group, arylsulfonyl group, alkoxycarbonyl group, aryl Represents an oxycarbonyl group, an alkylcarbonyl group, an arylcarbonyl group, an acyloxy group, a carboxyl group, a carbonyl group, a sulfonyl group, an amino group, a hydroxy group or a heterocyclic group, and when n is 2 or more, each R ₉ is They may be the same or different, and may be linked together to form a condensed ring. ]

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