JP4569170B2 - Display element and method for forming composite electrode - Google Patents

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 display and browse electronic information are increasing more and more.

  As such electronic information display browsing means, a conventional liquid crystal display, a CRT, and a new light emitting type such as an organic EL display are mainly used. However, particularly when the electronic information is document information, the display is relatively long. It is necessary to watch the browsing means, and these actions are not necessarily human-friendly means. Known disadvantages of light-emitting displays include flickering eyes, inconvenient to carry, restricted reading posture, need to focus on a static screen, and increased power consumption when read for a long time. It has been.

  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 uses the difference in refractive index between organic substances, so that the contrast of the obtained image is not sufficient. In addition, the polymer network type liquid crystal has problems such as a high voltage and a need for a complicated TFT circuit 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 aggregation of electrophoretic particles. In addition, the electrochromic display element can be driven at a low voltage of 3V or less, but the color quality of black or color (yellow, magenta, cyan, blue, green, red, etc.) is not sufficient, and the memory property is ensured. Therefore, there is a concern that the display cell needs a complicated film configuration such as a vapor deposition film.

  An electrodeposition (hereinafter abbreviated as ED) method that utilizes dissolution or precipitation of a metal or a metal salt is known as a display method that eliminates the drawbacks of each of the above-described methods. 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 Documents 1 to 3). 3).

As a result of examining the techniques disclosed in each of the above-mentioned patent documents in detail, the present inventor, in the prior art, is an electrode derived from performing an oxidation-reduction reaction by directly contacting an electrolyte solution and an electrode material peculiar to the ED system. Durability, especially as the display area of the display element becomes larger, the degree of deterioration becomes remarkable, and when a plastic substrate is used, it has been found that there is a problem with the bending resistance of the transparent electrode. . In addition, there is no mention or suggestion regarding the durability problem with respect to the electrode and the configuration defined in the present invention.
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 its object is a display element that can be driven at a low voltage with a simple member configuration, has a high display contrast, and has durability and bending resistance of electrodes. An object of the present invention is to provide an excellent display element.

  The above problem could be solved by the following configuration.

(Claim 1)
A display element having an electrolyte layer containing silver or a compound containing silver in a chemical structure between counter electrodes, and driving the counter electrode so as to cause dissolution and precipitation of silver. display device at least one way of the electrodes of the electrode, Ri composite electrode der the metal auxiliary electrode was attached to the transparent electrode, where the metal auxiliary electrode, characterized in that it comprises silver or copper.

(Claim 2)
The display element according to claim 1, wherein the transparent electrode contains at least one kind of iridium or tin.

(Claim 3)
The display element according to claim 1, wherein the transparent electrode contains a conductive polymer.

(Claim 4 )
Display device according to any of claims 1-3, characterized in that the display unit area of the display device is 50 cm ² or more.

(Claim 5 )
When the electrolyte layer contains a compound containing a mercapto group, the total mole number of sulfur atoms of the mercapto group in the electrolyte layer is [-SH], and the total mole number of silver in the electrolyte layer is [Ag], display device according to any one of claim 1 to 4, characterized in that satisfies the following formula (1).

Formula (1)
2 ≦ [−SH] / [Ag] ≦ 10
(Claim 6 )
The method for forming a composite electrode of a display element according to any one of claims 1 to 5 , wherein at least one of the transparent electrode and the metal auxiliary electrode is formed by a printing method. Method.

(Claim 7 )
In the method for forming the composite electrode of the display element according to any one of claim 1 to 5, at least 1-way transparent electrode and a metal auxiliary electrode, the internal diameter for ejecting charged liquid has the following nozzle 30μm The liquid discharge apparatus includes a liquid discharge head, supply means for supplying a solution into the nozzle, and discharge voltage application means for applying a discharge voltage to the solution in the nozzle. A method for forming a composite electrode.

  According to the present invention, it is possible to provide a display element that can be driven at a low voltage with a simple member configuration, has a high display contrast, and has excellent durability and bending resistance of electrodes. It was.

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

  The present inventor has a display element that has an electrolyte layer containing silver or a compound containing silver in a chemical structure between the counter electrodes, and that drives the counter electrode so as to cause dissolution and precipitation of silver. By using a composite electrode in which a metal auxiliary electrode is attached to a transparent electrode as at least one electrode of the counter electrode, it can be driven at a low voltage with a simple member configuration, and has a high display contrast. In addition, the inventors have found that the electrode is excellent in durability and bending resistance, and have reached the present invention.

  In the conventional example of the display element by the ED method, there are many examples in which an ITO electrode formed by a physical method such as a sputtering method is used as the transparent electrode. The ITO electrode has an advantage of relatively low resistance and high light transmittance. However, when the electrode material is in direct contact with an electrolyte material such as an ED display element, structural defects such as a crystal grain boundary and a porous crystal structure are present. Liquid electrolyte soaks in and damages the substrate, reducing the durability. Especially when a flexible resin substrate is used as the substrate of the display element, the width of the decrease is amplified according to the bending of the display element. It turned out that there is a tendency.

  A method of coexisting a resin component such as a polymer in order to fill the structural defect of the ITO electrode is also known, but this method can certainly prevent the liquid electrolyte from penetrating into the substrate, but the resistance value of the electrode is high. Therefore, a higher voltage or a higher quantity of electricity is required for driving the ED method element. By using the metal auxiliary electrode having the configuration of the present invention, the conductivity of the entire electrode is increased, and a low voltage and a low electric quantity can be achieved. In addition, it is possible to add a resin or the like that increases the resistance to the transparent electrode portion of the composite electrode, preventing the penetration of the liquid electrolyte into the substrate, and further improving the flexibility of physical strength. I found that I was able to solve specific problems.

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

  The display element of the present invention has an electrolyte layer containing silver or a compound containing silver in the chemical structure between the counter electrodes, and performs a driving operation of the counter electrode so as to cause dissolution and precipitation of silver. It is.

[Silver or a compound containing silver in the chemical structure]
Silver or a compound containing silver in the chemical structure according to the present invention is a general term for compounds such as silver oxide, silver sulfide, metallic silver, silver colloidal particles, silver halide, silver complex compounds, and silver ions. Phase state species such as solid state, solubilized state in liquid, and gas state, and charged state species such as neutral, anionic, and cationic are not particularly limited.

[Basic cell structure]
FIG. 1 is a schematic cross-sectional view showing the basic configuration of the display element of the present invention.

  In FIG. 1, the display device of the present invention holds an electrolyte layer 2 between a pair of counter electrodes 1 and applies a voltage or a current from the power source 3 to the counter electrode 1, whereby silver contained in the electrolyte layer 2. The display element changes the display state by utilizing the difference in the optical properties of light transmission and absorption of the compound containing silver.

(Composite electrode)
The display element according to claim 1 of the present invention has an electrolyte layer containing silver or a compound containing silver in a chemical structure between the counter electrodes, and driving the counter electrode so as to cause dissolution and precipitation of silver. A display element for performing operation, wherein at least one of the counter electrodes is a composite electrode in which a metal auxiliary electrode is attached to a transparent electrode.

The transparent electrode of the present invention refers to an electrode having a light transmittance of 80% or more and a resistivity of 1 × 10 ⁻³ Ω · cm or less in a wavelength range of 380 nm to 780 nm.

  The composite electrode of the present invention includes a transparent electrode portion and a metal auxiliary electrode portion that are in electrical contact. Examples of the composite electrode in which the transparent electrode and the metal auxiliary electrode are in contact with each other include the forms shown in FIGS. The area coverage of the metal electrode viewed from the display element observation side is preferably 30% or less from the viewpoint of white display reflectance and black display reflectance due to a decrease in aperture ratio, and more preferably 10% or less.

  Hereinafter, the structural example of the composite electrode comprised from a transparent electrode part and a metal auxiliary electrode part is demonstrated using FIG.

  FIG. 2A is a perspective view showing an example of a composite electrode used in the present invention, and FIG. 2B is a cross-sectional view taken along the line AA ′ of FIG. As shown in FIGS. 2A and 2B, a plurality of transparent electrodes 11 are formed on the substrate 10, and one transparent electrode 11 is provided at one end along the longitudinal direction of the transparent electrode 11. A metal auxiliary electrode 12 is formed so as to cover the portion.

  FIG. 2C is a perspective view showing an example of the composite electrode used in the present invention, and FIG. 2D is a cross-sectional view taken along the line BB ′ of FIG. As shown in FIGS. 2C and 2D, a plurality of metal auxiliary electrodes 22 are formed on the substrate 20, and the transparent electrodes 21 are arranged in the longitudinal direction so as to cover the two metal auxiliary electrodes 22. Is formed. 2E, 2F, and 2G show other pattern examples of the composite electrode used in the present invention by cross-sectional views.

  FIG. 3 is a plan view of the composite electrode used in the present invention. In FIG. 3A, one metal auxiliary electrode 62 is disposed in the approximate center of the transparent electrode 61. In FIG. 3B, a total of two metal auxiliary electrodes 72 are disposed at both ends of the transparent electrode 71 in the longitudinal direction. FIG. 3C shows that metal auxiliary electrodes are formed at both ends of the transparent electrode 81, and these metal auxiliary electrodes are connected in a ladder shape. With the structure of FIGS. 3B and 3C, even if some of the electrodes are cut due to damage, the other electrode or other connection circuit can be used to reduce the resistance without disconnection. Can be achieved.

(Transparent electrode part)
The transparent electrode of the present invention 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 can be used.

  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.

  It is also possible to produce a transparent electrode by applying a liquid in which ITO fine powder baked at 350 ° C. to 800 ° C. is dispersed in a solution containing a solvent and a polymer to the substrate and volatilizing the solvent or curing the polymer. is there. 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 and so on to cause coprecipitation reaction while maintaining PH at 9, and separating and washing 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 solution in which about 10% of organic indium and organic tin are blended in a xylol at a mass ratio of 97: 3 is applied on a substrate, and the solvent is volatilized and baked at 100 ° C. to 150 ° C. to solidify. This 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 above 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.

(Metal auxiliary electrode)
The metal auxiliary electrode of the present invention refers to an electrode using a metal material such as platinum, gold, silver, copper, aluminum, zinc, nickel, titanium, bismuth, and alloys thereof. The surface resistance value of the metal electrode portion is preferably 10Ω / □ or less, and more preferably 1Ω / □ or less. The film thickness is preferably 0.2 μm or more and 50 μm or less.

(Electrode manufacturing method)
A known method can be used to form the transparent electrode and the metal auxiliary electrode. 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.

  Among the ink jet systems, the following electrostatic ink jet can print a highly viscous liquid continuously with high accuracy, and is preferably used for forming the transparent electrode and the metal auxiliary electrode of the present invention. The viscosity of the ink is preferably 30 mPa · s or more, and more preferably 100 mPa · s or more.

(Electrostatic inkjet)
In the display element of the present invention, at least one of the transparent electrode of the composite electrode and the metal auxiliary electrode has a liquid discharge head having a nozzle with an internal diameter of 30 μm or less for discharging a charged liquid, and supplies a solution into the nozzle. Preferably, it is formed using a liquid discharge apparatus including a supply unit that performs the discharge voltage application unit that applies a discharge voltage to the solution in the nozzle.

  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 includes a swell operation of the solution by the convex meniscus forming unit and application of the discharge voltage. And a second discharge control unit that performs the operation in synchronism with the liquid, and the operation control unit is configured to supply the liquid at the tip of the nozzle after the swell operation of the solution and application of the discharge voltage. It is also a preferred form to use a liquid discharge apparatus having a liquid level stabilization control unit that performs operation control for drawing the surface inward.

  By producing an electrode pattern using such an electrostatic inkjet, it is advantageous that an electrode having excellent on-demand characteristics, little waste material, and excellent dimensional accuracy can be obtained.

(Ratio of sulfur atom to silver atom in mercapto compounds)
In the display element of the present invention, the electrolyte layer contains a mercapto compound, the total mole number of sulfur atoms of the mercapto group in the electrolyte layer is [-SH], and the total mole number of silver in the electrolyte layer is [Ag]. ], 2 ≦ [−SH] / [Ag] ≦ 10 is satisfied. When [-SH] / [Ag] is less than 2, the silver block is not sufficient, and the blackening of the silver may occur when the basic compound is present in the coexisting substance at high temperature and high humidity. This leads to a decrease in reflectance when white and whiteness contamination. On the other hand, when [-SH] / [Ag] exceeds 10, the dissolution rate of silver black by the mercapto compound is increased, leading to deterioration of memory properties. In the present invention, a more preferable range is 2.5 ≦ [−SH] / [Ag] ≦ 5. In addition, the sulfur atom of the mercapto group of the mercapto compound in the electrolyte layer referred to in the present invention includes a sulfur atom existing in the form of S 2 ^- or silver sulfide in addition to the mercapto group.

  Further, the mercapto compound is preferably a compound having a molecular weight satisfying the condition of 50 ≦ molecular weight ≦ 149. When the molecular weight of the mercapto compound is less than 50, there is an odor and the workability is inferior, and when the molecular weight exceeds 150, the mass concentration increases and consequently the solubility of the compound necessary for electrical conductivity is lowered. As a result, the driving speed is slow, which is disadvantageous.

  The mercapto compound is preferably used in combination of a plurality of compound species. By containing a plurality of compound types, an improvement in the dissolution molar concentration of silver and an effect of preventing precipitation at a low temperature of the electrolyte solution can be obtained.

(Electrolyte solvent)
In the display element of the present invention, the electrolyte layer is composed of propylene carbonate, ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, butylene carbonate, γ-butyl lactone, tetramethyl urea, 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, diethoxy furan, tetrahydrofuran, ethylene glycol, diethylene glycol, preferably contains at least one solvent selected from triethylene glycol monobutyl ether and water.

  Among the solvents described above, 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. Examples of the solvent having a freezing point of −20 ° C. or lower and a boiling point of 120 ° C. or higher include propylene carbonate, ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, γ-butyl lactone, 2- (N-methyl) -2-pyrrolidinone. , N-methylpropionamide, N, N dimethylformamide, and acetylacetone.

  As other solvents that 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).

(Electrolyte material)
In the display element of the present invention, when the electrolyte is a liquid, the following compounds can be included in the electrolyte. 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, tetraethylammonium borofluoride as tetraalkylammonium compounds And 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.

  Further, when the supporting electrolyte is a solid, the following compounds exhibiting electron conductivity and ion conductivity can be contained in the electrolyte.

Vinyl fluoride polymer containing perfluorosulfonic acid, polythiophene, polyaniline, polypyrrole, triphenylamines, polyvinylcarbazoles, polymethylphenylsilanes, Cu ₂ S, Ag ₂ S, Cu ₂ Se, AgCrSe _2, etc. F-containing compounds such as chalcogenide, CaF ₂ , PbF ₂ , SrF ₂ , LaF ₃ , TlSn ₂ F ₅ , CeF ₃ , Li salts such as Li ₂ SO ₄ , Li ₄ SiO ₄ , Li ₃ PO ₄ , ZrO ₂ , CaO _{, Cd 2 O 3, HfO 2} , Y2O 3, Nb 2 O 5, WO 3, Bi 2 O 3, AgBr, AgI, CuCl, CuBr, CuBr, CuI, LiI, LiBr, LiCl, LiAlCl 4, LiAlF 4, AgSBr _{, C 5 H 5 NHAg 5 I} 6, Rb 4 Cu 16 I 7 Cl 13, Rb 3 Cu 7 Cl 10, LiN, Li 5 NI 2 Compounds such as li ₆ NBr _3, and the like.

  Moreover, a gel electrolyte can also be used as the supporting electrolyte. When the electrolyte is non-aqueous, the oil gelling agents described in paragraphs [0057] to [0059] of JP-A No. 11-185836 can be used.

(White particles with added electrolyte)
In the display element of the present invention, the electrolyte layer preferably includes white particles.

  Examples of the white particles according to the present invention include titanium dioxide (anatase type or rutile type), barium sulfate, calcium carbonate, aluminum oxide, zinc oxide, magnesium oxide and zinc hydroxide, magnesium hydroxide, magnesium phosphate, and phosphoric acid. Magnesium hydrogen, 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 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.

In the present invention, among the white particles, titanium dioxide, zinc oxide, and zinc hydroxide are preferably used. In addition, titanium dioxide surface-treated with inorganic oxides (Al ₂ O ₃ , AlO (OH), SiO _2, etc.), in addition to these surface treatments, trimethylolethane, triethanolamine acetate, trimethylcyclosilane, etc. Titanium dioxide subjected to organic treatment can be used.

  Of these white particles, it is more preferable to use titanium oxide or zinc oxide from the viewpoint of coloring prevention at high temperature and the reflectance of the element due to the refractive index.

(Thickener added with electrolyte)
In the display element of the present invention, a thickener can be used in the electrolyte layer. For example, gelatin, gum arabic, poly (vinyl alcohol), hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, poly ( Vinylpyrrolidone), poly (alkylene glycol), casein, starch, poly (acrylic acid), poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid), copoly (styrene-maleic anhydride), copoly ( Styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters), poly (urethanes), phenoxy resins, poly (PVC Redene), poly (epoxides), poly (carbonates), poly (vinyl acetate), cellulose esters, poly (amides), hydrophobic transparent binders such as polyvinyl butyral, cellulose acetate, cellulose acetate butyrate, polyester, Examples include polycarbonate, polyacrylic acid, polyurethane and the like.

  These thickeners may be used in combination of two or more. Moreover, the compound as described in pages 71-75 of Unexamined-Japanese-Patent No. 64-13546 can be mentioned. Among these, the compounds preferably used are polyvinyl alcohols, polyvinyl pyrrolidones, hydroxypropyl celluloses, and polyalkylene glycols from the viewpoint of compatibility with various additives and improvement in dispersion stability of white particles.

(Other additives for electrolyte layer)
In the display element of the present invention, the constituent layers that can be provided between the counter electrodes including the electrolyte layer include auxiliary layers such as a protective layer, a filter layer, an antihalation layer, a crossover light cut layer, and a backing layer. In these auxiliary layers, various chemical sensitizers, noble metal sensitizers, photosensitive dyes, supersensitizers, couplers, high boiling point solvents, antifoggants, stabilizers, development inhibitors, bleaches Accelerator, Fixing accelerator, Color mixing inhibitor, Formalin scavenger, Toning agent, Hardener, Surfactant, Thickener, Plasticizer, Slipper, UV absorber, Irradiation dye, Filter light absorber, A dusting agent, a polymer latex, a heavy metal, an antistatic agent, a matting agent and the like can be contained as necessary.

  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
(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.

(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.

(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 as not to leak outside, and is also called sealing agent, epoxy resin, urethane resin, acrylic resin, vinyl acetate resin, enthiol resin, silicone resin, modified polymer resin A curing type such as a thermosetting type, a photocuring type, a moisture curing type, an anaerobic curing type, or the like 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 region 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 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 pair of stacked substrates is heated while being pressed from both sides, whereby the display cells are obtained. In order to obtain a display element, an electrolyte composition may be injected between substrates by a vacuum injection method or the like. Alternatively, when the substrates are bonded together, the electrolyte composition may be dropped on one substrate, and the liquid crystal composition may be sealed simultaneously with the bonding of the substrates.

(Display element driving method)
In the display element of the present invention, it is preferable that the driving operation of the counter electrode described above is simple 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 display element 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.

(Application field of the display element of the present invention)
The display element 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 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, Cash card, credit card, highway card, driver's license, hospital examination card, health insurance card, basic resident register, passport, etc. It can also be used as an electronic book terminal, a display, and a document viewer.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to this.
Example 1
Production of display element 1 <comparative example>
(Preparation of electrolyte solution 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 0.5 g of titanium oxide was added and the titanium oxide was dispersed with an ultrasonic disperser. . 150 mg of polyvinyl alcohol (degree of saponification: about 87-89%, degree of polymerization: 4500) was added to this solution and stirred for 1 hour while heating at 120 ° C. to obtain an electrolyte solution 1.

(Preparation of transparent electrode 1)
An ITO film is formed on the entire surface by a known sputtering method on a 2 cm × 4 cm glass substrate having a thickness of 1.5 mm, and an electrode pattern having an electrode interval of 30 μm and an electrode width of 180 μm is formed on the glass substrate by using a photolithographic method. The transparent electrode 1 which has in a longitudinal direction was obtained.

(Production of metal electrodes)
After forming a Cu film on the entire surface by a known sputtering method on a 2 cm × 4 cm glass substrate having a thickness of 1.5 mm, a pattern with an electrode interval of 30 μm and an electrode width of 180 μm is formed in the longitudinal direction of the glass substrate using a photolithographic method. Then, 10 μm of silver was deposited on the Cu pole by electrolytic plating to obtain a silver electrode (electrode 2).

(Production of display element)
A solution prepared by adding polyacrylic spherical beads having an average particle diameter of 20 μm to the prepared electrolyte solution 1 so that the volume fraction is 4% by volume is applied onto the electrode 2, and Thus, the display element 1 was fabricated by sandwiching the electrodes 1 in a perpendicular direction and pressing them with a pressure of 9.8 kPa to seal the periphery. The overlapped portion of 2 cm × 2 cm is a display portion, and the remaining portion is used as a lead portion.

Production of Display Element 2 <Comparative Example>
A display element 2 was produced in the same manner except that the transparent electrode 1 was changed as follows and the transparent electrode 2 was used.

(Preparation of transparent electrode 2)
An aqueous solution containing 35% by mass of InCl ₃ and an aqueous solution containing 80% by mass of SnCl ₄ were mixed, and while maintaining the solution temperature at 27 ° C., 6.3% ammonia water was gradually added to adjust the pH of the aqueous solution to 9. It adjusted so that it might become. This solution was stirred at 27 ° C. for 50 minutes to obtain a coprecipitated hydroxide of In and Sn. The coprecipitate was separated by filtration, washed with ion exchange water, and then fired at 500 ° C. for 2.5 hours to obtain an aggregate of acicular ITO particles. The particles were mechanically pulverized to obtain ITO fine powder. 2 parts by mass of the obtained ITO fine powder, 1.8 parts by mass of a blocked isocyanate compound (methyl ethyl ketoxime block of hexamethylene diisocyanate boulet trimer), 12 parts by mass of ethyl carbitol acetate, terephthalic acid / isophthalic acid / sebacic acid A transparent electrode solution 1 was prepared by mixing 4 parts by mass of a polyester resin having a composition of / ethylene glycol / neopentyl glycol = 0.3 / 0.1 / 0.15 / 0.25 / 0.2 (molar ratio). . This solution is applied to a glass substrate with a film thickness of 60 μm by screen printing, heated at 150 ° C. for 2 minutes with IR light, and a transparent electrode 2 having an electrode pattern with an electrode interval of 30 μm and an electrode width of 180 μm in the longitudinal direction of the glass substrate Was made.

Production of Display Element 3 <Invention>
A display element 3 was produced in the same manner except that the transparent electrode 1 of the display element 1 was changed to the composite electrode 1 described below.

(Preparation of composite electrode 1)
On a 2 cm × 4 cm glass substrate having a thickness of 1.5 mm, Ni electrodes having a width of 20 μm were formed in the longitudinal direction of the glass substrate at a pitch of 210 μm by a printing method using a known Ni paste ink. Next, after an ITO film is formed on the entire surface by sputtering, an electrode pattern with an electrode interval of 30 μm and an electrode width of 180 μm is formed using a photolithographic method so that the center of the Ni electrode coincides with the center of the ITO electrode. As a result, a composite electrode 1 was obtained. Refer to FIG.

Production of Display Element 4 <Invention>
A display element 4 was produced in the same manner except that the transparent electrode 1 of the display element 1 was changed to the composite electrode 2 described below.

(Preparation of composite electrode 2)
On a glass substrate having a thickness of 1.5 mm and 2 cm × 4 cm, Cu electrodes having a width of 210 μm and a width of 20 μm were formed in the longitudinal direction of the glass substrate by a printing method using a known Cu paste ink. Next, after a ZnAlO film is formed on the entire surface by sputtering, an electrode pattern with an electrode interval of 30 μm and an electrode width of 180 μm is formed using a photolithographic method so that the center of the Cu electrode coincides with the center of the ZnAlO electrode. As a result, a composite electrode 2 was obtained. Refer to FIG.

Production of display element 5 <present invention>
A display element 5 was produced in the same manner except that the transparent electrode 1 of the display element 1 was changed to the composite electrode 3 described below.

(Preparation of composite electrode 3)
On a glass substrate having a thickness of 1.5 mm and a size of 2 cm × 4 cm, Ag electrodes having a width of 210 μm and a width of 20 μm were formed by a printing method using a known Ag paste ink. Next, after an ITO film is formed on the entire surface by sputtering, an electrode pattern with an electrode interval of 30 μm and an electrode width of 180 μm is used by a photolithographic method so that the center of the Ag electrode coincides with the center of the ITO electrode. The composite electrode 3 was obtained. Refer to FIG.

Production of display element 6 <present invention>
A display element 6 was produced in the same manner except that the transparent electrode 1 of the display element 1 was changed to the composite electrode 4 described below.

(Preparation of composite electrode 4)
On a 2 cm × 4 cm glass substrate having a thickness of 1.5 mm, Ni electrodes having a width of 20 μm were formed in the longitudinal direction of the glass substrate at a pitch of 210 μm by a printing method using a known Ni paste ink. Next, an electrode pattern with an electrode spacing of 30 μm and an electrode width of 180 μm is screened using conductive polymer poly (3,4-ethylenedioxythiophene) so that the center of the Ni pole coincides with the center of the pole. A composite electrode 4 was obtained by printing. Refer to FIG.

Production of display element 7 <present invention>
A display element 7 was produced in the same manner except that the transparent electrode 1 of the display element 1 was changed to the composite electrode 5 described below.

(Preparation of composite electrode 5)
On a glass substrate having a thickness of 1.5 mm and a size of 2 cm × 4 cm, an Ag electrode having a width of 20 μm was formed in the longitudinal direction of the glass substrate at a pitch of 210 μm by a printing method using a known Ag paste ink. Next, an electrode pattern having an electrode interval of 30 μm and an electrode width of 180 μm is screened using a conductive polymer poly (3,4-ethylenedioxythiophene) so that the center of the Ag pole coincides with the center of the pole. A composite electrode 5 was obtained by printing. Refer to FIG.

Production of display element 8 <present invention>
A display element 8 was produced in the same manner except that the transparent electrode 1 of the display element 1 was changed to the composite electrode 6 described below.

(Preparation of composite electrode 6)
On a glass substrate having a thickness of 1.5 mm and 2 cm × 4 cm, an Ag electrode having a pitch of 210 μm and a width of 20 μm was formed in the longitudinal direction of the glass substrate using a known Ag paste ink by a printing method. Next, an electrode pattern having an electrode interval of 30 μm and an electrode width of 180 μm is formed by a printing method using the transparent electrode solution 1 of the transparent electrode 2 so that the center of the Ag electrode coincides with the center of the electrode. 6 was obtained. Refer to FIG.

Production of display element 9 <Invention>
A display element 9 was produced in the same manner except that the transparent electrode 1 of the display element 1 was changed to the composite electrode 7 described below.

(Preparation of composite electrode 7)
Using a known electrostatic ink jet printer with a nozzle tip inner diameter of 10 μm on a 2 cm × 4 cm glass substrate with a thickness of 1.5 mm, Ag paste ink with a width of 10 μm and intervals of 160 μm and 30 μm alternately. A pattern was applied and an Ag electrode was formed in the longitudinal direction of the glass substrate. Next, a transparent electrode of 180 μm is formed by using the transparent electrode solution 1 of the transparent electrode 2 by an electrostatic ink jet printer so as to simultaneously cover the electrode interval of 160 μm and the two Ag electrodes (10 μm × 2). 7 was obtained. Refer to FIG.

Production of display element 10 <present invention>
A display element 10 was produced in the same manner except that the electrolyte solution 1 of the display element 1 was changed to the following electrolyte solution 2 and the transparent electrode 1 was changed to the composite electrode 7.

(Preparation of electrolyte solution 2)
After 20 mg of p-toluenesulfonate and 45 mg of 3-mercapto-1,2,4-triazole were added and completely dissolved in 2.5 g of propylene carbonate, 0.5 g of titanium oxide was added and ultrasonically dispersed. The titanium oxide was dispersed with a machine. 100 mg of polyethylene glycol (average molecular weight 500,000) was added to this solution and stirred for 1 hour while heating at 120 ° C. to obtain an electrolyte solution 2.

Evaluation method (Evaluation 1 Evaluation of durability under high temperature and high humidity ratio of reflectance)
Each manufactured display element was left in a constant temperature and humidity chamber at 80 ° C. and a relative humidity of 60% for 1 week to prepare a forced deterioration sample. Next, using an untreated sample that has not undergone forced deterioration, the amount of electricity for driving is adjusted as appropriate, and the reflectance is monitored by a spectrophotometer, while the reflectance at 450 nm when the display element is blackened is about 10%. The amount of electricity (amount of electricity 1) to be (reflectance 1) was determined. Next, this amount of electricity 1 was applied to the sample subjected to forced deterioration to blacken the display element, and the reflectance 2 at this time was obtained with a spectrophotometer. The ratio of reflectance ratio = reflectance 2 / reflectance 1 was determined, and the closer this ratio is to 1, the better the durability under high temperature and high humidity.

(Evaluation 2: Evaluation of durability under high temperature and high humidity ratio of electrode resistance)
Each manufactured display element was left in a constant temperature and humidity chamber at 80 ° C. and a relative humidity of 60% for 1 week to prepare a forced deterioration sample. Next, a resistance value R1 for 10 transparent electrodes was determined using an untreated sample that was not subjected to forced deterioration. Next, the resistance value 2 for 10 electrodes of the transparent electrode was similarly obtained for the sample subjected to forced deterioration. The ratio of resistance value = resistance value 2 / resistance value 1 is obtained. The closer this ratio is to 1, the better the durability of the electrode under high temperature and high humidity.

  Table 1 shows the results of Evaluation 1 and Evaluation 2 for each of the manufactured display elements.

  As shown in Table 1, in the durability evaluation under high temperature and high humidity, a clear correlation is seen between the reflectance ratio and the electrode resistance ratio, and the decrease in the degree of blackening after forced deterioration is caused by the disconnection of the electrode, etc. It became clear that it was caused by an increase in resistance value. It has been found that the electrode deterioration peculiar to the ED method is improved by using the configuration of the present invention. Table 1 also shows that the reflectance of the display element after the high temperature and high humidity treatment is lower than that before the treatment. In order to prevent this decrease in reflectivity, an apparent equivalent reflectivity can be obtained before and after the process by applying a voltage or an amount of electricity required before the process after the drive process. Since the voltage or the amount of electricity and the blackening amount of the display element have a positive correlation, the configuration of the present invention can be corrected with a smaller voltage or amount of electricity, which is advantageous compared to the comparative example. This shows the advantage of being able to drive with low voltage and low voltage.

Example 2
Display elements 11 to 20 were manufactured in exactly the same manner except that the glass substrates of display elements 1 to 10 manufactured in Example 1 were changed to a polyethylene terephthalate resin substrate having a thickness of 100 μm.

(Evaluation 3 Bending resistance Reflectance ratio)
While appropriately adjusting the amount of electricity for driving and monitoring the reflectance with a spectrophotometer, the blackening is stopped when the reflectance at 450 nm when the blackening of the display element is about 10% (reflectance 1). The amount of electricity required at times (= the amount of electricity 1) was determined. Next, after fixing the both ends of the display element and repeating the operation of changing the positions of the fixed ends so that the maximum curvature radius of the display element is 2 cm or less, the display element is similarly supplied with the amount of electricity 1 It was blackened and the reflectance at 450 nm (= reflectance 2) was measured. The ratio of reflectance ratio = reflectance 2 / reflectance 1 is obtained, and the closer this ratio is to 1, the better the bending resistance.

(Evaluation 4 Bending resistance Electrode resistance ratio)
The resistance value R1 for 10 transparent electrodes was determined. Next, the bending test described in Evaluation 3 was performed, and similarly, a resistance value 2 for 10 transparent electrodes after the bending test was obtained. The ratio of resistance value = resistance value 2 / resistance value 1 is obtained. The closer this ratio is to 1, the better the durability of the electrode under high temperature and high humidity. Table 2 shows the results of evaluations 3 and 4 for each of the manufactured display elements.

  As shown in Table 2, in the bending test evaluation, there is a clear correlation between the reflectance ratio and the electrode resistance ratio, and the decrease in the degree of blackening after the bending test is due to an increase in the resistance value due to electrode disconnection or the like. It became clear that it was caused. It has been found that the electrode deterioration peculiar to the ED method is improved by using the configuration of the present invention.

Example 3
As a result of performing the same evaluation by changing the display area of the display element manufactured in Example 1 and Example 2 to 8 cm × 8 cm, the comparative example was deteriorated by about 10% with respect to the results of Examples 1 and 2. Although the degree is large, the present invention has almost the same result as that of Examples 1 and 2, and it has been found that the effect of the present invention can be obtained more as the display screen becomes larger.

It is a schematic sectional drawing which shows the basic composition of the display element of this invention. It is a figure which shows the structural example of the composite electrode comprised from a transparent electrode part and a metal auxiliary electrode part. It is a top view of the composite electrode used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Counter electrode 2 Electrolyte layer 3 Power supply 4 Ground 10, 20, 30, 40, 50 Base material 11, 21, 31, 41, 51, 61, 71, 81 Transparent electrode 12, 22, 32, 42, 52, 62, 72,82 Metal auxiliary electrode

Claims (7)

A display element having an electrolyte layer containing silver or a compound containing silver in a chemical structure between counter electrodes, and driving the counter electrode so as to cause dissolution and precipitation of silver. display device at least one hand of the electrodes of the electrode, Ri composite electrode der the metal auxiliary electrode was attached to the transparent electrode, where the metal auxiliary electrode, characterized in that it comprises silver or copper. The display element according to claim 1, wherein the transparent electrode contains at least one kind of iridium or tin. The display element according to claim 1, wherein the transparent electrode contains a conductive polymer. The display element according to claim 1, wherein a display area of the display element is 50 cm ² or more . When the electrolyte layer contains a compound containing a mercapto group, the total mole number of sulfur atoms of the mercapto group in the electrolyte layer is [-SH], and the total mole number of silver in the electrolyte layer is [Ag], The display element according to claim 1, wherein the following expression (1) is satisfied .
Formula (1)
2 ≦ [−SH] / [Ag] ≦ 10 6. The method for forming a composite electrode of a display element according to claim 1, wherein at least one of the transparent electrode and the metal auxiliary electrode is formed by a printing method. Method. 6. The method for forming a composite electrode of a display element according to claim 1, wherein at least one of the transparent electrode and the metal auxiliary electrode has a nozzle having an internal diameter for discharging charged liquid of 30 [mu] m or less. The liquid discharge apparatus includes a liquid discharge head, supply means for supplying a solution into the nozzle, and discharge voltage application means for applying a discharge voltage to the solution in the nozzle. A method for forming a composite electrode.

Images