JP2008122829A - Display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display element having a fast display speed and improved durability of electrodes. <P>SOLUTION: The display element has an electrolyte containing silver or a compound containing silver in a chemical structure between counter electrodes and drives to operate the counter electrodes to produce dissolution deposition of silver, wherein at least one of the counter electrodes comprises an electrode having nitrogen-containing carbon electrode layer. <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 system can be driven at a low voltage of 3 V or less, and has advantages such as a simple cell configuration, excellent black-to-white contrast and black quality. US Pat. No. 4,240,716, Patent No. Various methods are disclosed in Japanese Patent No. 3428603, Japanese Patent Application Laid-Open No. 2003-241227, and the like.

  As a result of a detailed examination of the techniques disclosed in the above-mentioned patent documents, the inventor of the present invention has a configuration of an electrolyte containing silver halide and alkali halide, and repeatedly drives with this configuration. In low voltage driving where halogen compounds are not oxidized / reduced, the driving speed is not sufficient. When the driving voltage is increased to increase the apparent oxidation / reduction rate of silver oxidation / reduction, the electrolyte may be colored or the halogen oxide However, it has been found that there is a problem that the electrode durability is not sufficient due to a local battery reaction that corrodes the metal electrode of the counter electrode.

  When writing and erasing are repeated in an ED method display element using silver field deposition, the counter electrode (non-display side) component and silver are exchanged, leading to deterioration of the counter electrode. As the counter electrode deteriorates, the image display speed and the erasing speed are lowered, and there is a problem that writing becomes impossible.

  On the other hand, in the electrodeposition method, as one method for improving the resistance of the counter electrode, an electrode forming method using carbon is known in patent documents and the like.

  For example, as an optical device that reduces the material cost of the counter electrode of the optical filter that controls the light transmittance using silver deposition from the silver salt solution on the ITO transparent electrode, at least one surface of the counter electrode is An optical device containing one type of conductive particles and at least one type of binder and using a carbon material as the conductive particles is disclosed (for example, see Patent Document 1). Further, in an optical device that has a working electrode, a counter electrode, and an electrolytic solution disposed in contact with these electrodes and is electrochemically dimmed by an electric field applied to the electrolytic solution, a conductive material is used in the specification. It describes that a carbon material that is a conductive particle is mixed with a binder to form a counter electrode (for example, see Patent Document 2). In addition, in an optical device used for an optical filter or the like capable of controlling light transmittance or light reflectance in a visible light region, a counter electrode having a laminated structure and including a carbon material at the top is disclosed. (For example, refer to Patent Documents 3 and 4).

  Generally, by using a carbon electrode as a counter electrode, it is said that a display element that can withstand repeated rewriting can be formed without deterioration of the counter electrode. However, the carbon electrode has a problem in that the display speed is slow because it lacks the power supply capability compared to the commonly used ITO (Sn-doped indium oxide) electrode and metal electrode.

However, none of the above-mentioned patent documents discloses any means for improving electrode resistance while ensuring a sufficient display speed, and there is no suggestion about the nitrogen-containing carbon electrode layer of the present invention. .
JP-A-10-274790 JP 2001-59980 A JP 2001-51307 A JP 2001-51308 A

  The present invention has been made in view of the above problems, and an object thereof is to provide a display element having a high display speed and improved electrode resistance.

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

  1. A display element having an electrolyte 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. At least one is an electrode having a nitrogen-containing carbon electrode layer.

  2. 2. The display element according to 1 above, wherein the nitrogen-containing carbon electrode layer has a porous structure.

  3. 3. The nitrogen atom contained in the nitrogen-containing carbon electrode layer is contained in at least one bonding form selected from the following structural formulas [1], [2] and [3]. Display element.

  4). The nitrogen-containing carbon material for forming the nitrogen-containing carbon electrode layer is formed from a carbon compound having a nitrogen-containing five-membered ring structure or a nitrogen-containing six-membered ring structure. The display element as described in.

  5. 5. The display element according to 4 above, wherein the carbon compound having the nitrogen-containing five-membered ring structure or the nitrogen-containing six-membered ring structure is a compound represented by the following general formula (1) or (2).

[Wherein R ^{1 to} R ⁷ are each a cyano group, an amino group, an imino group, an N-oxide, a hydroxyamino group, a nitro group, a nitroso group, an azo group, a diazo group, an azide group, an alkyl group, and At least one selected from the induced bonds, and each may be the same or different. ]
6). 6. The non-carbon-type electrode exists in the state which contact | connected the said nitrogen-containing carbon electrode between the said nitrogen-containing carbon electrode layer and a board | substrate, The said any one of 1-5 characterized by the above-mentioned. Display element.

  7. 7. The display element according to 6, wherein the non-carbon electrode has a conductive layer, and the conductive layer contains silver.

  8). 8. The display element according to any one of 1 to 7, wherein the electrolyte does not substantially contain an alkali metal.

  9. 9. The display element according to any one of 1 to 8, wherein the electrolyte contains an organic solvent.

  10. The electrolyte contains at least one compound represented by the following general formula (3) or (4) and at least one compound represented by the following general formula (5) or (6). 10. The display element according to any one of 1 to 9 above.

[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 (5)
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. ]
11. The molar concentration of halogen ions or halogen atoms contained in the electrolyte is [X] (mol / kg), and the total molar concentration of silver contained in the electrolyte or the compound containing silver in the chemical structure is [Ag] ( The display element according to any one of 1 to 10 above, wherein the condition defined by the following formula (1) is satisfied:

Formula (1)
0 ≦ [X] / [Ag] ≦ 0.01

  According to the present invention, a display element having a high display speed and improved electrode resistance can be provided.

  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 the chemical structure between the counter electrodes, and the counter electrode so as to cause dissolution and precipitation of silver. A display element that performs an electrode driving operation, wherein at least one of the counter electrodes is an electrode having a nitrogen-containing carbon electrode layer, display speed is high, and electrode resistance is improved. It has been found that a display element can be realized and has reached the present invention.

  Hereafter, each element which comprises the display element of this invention is demonstrated.

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

[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.

[Electrode having a nitrogen-containing carbon electrode layer]
In the display element of the present invention, at least one of the counter electrodes is an electrode having a nitrogen-containing carbon electrode layer.

  In the field of electrochemistry, carbon electrodes are well known as one of the common electrodes. For example, carbon materials used in “Electronic Carbon Technology Complete Works” (edited by the Technical Information Association), etc. Etc. are introduced.

  The nitrogen-containing carbon electrode layer used in the display element of the present invention is a special carbon electrode containing nitrogen that does not exist in a general carbon electrode. As for the carbon electrode containing nitrogen in the inside, there is a report for an electric double layer capacitor, but none has been considered in regard to the effect relating to the electrochemical reaction as in the present invention.

  In the display element of the present invention, by using a nitrogen-containing carbon electrode as at least one of the counter electrodes, the resistance of the electrode itself is improved, and an improvement in display speed that cannot be achieved by a general carbon electrode is seen. I was able to.

  Although all of the reasons for achieving the above characteristics are not clear, it is presumed as follows.

  FIG. 1 is a conceptual diagram illustrating the principle of the display element of the present invention.

FIG. 1A shows a reaction that occurs when visualization is performed in the display element 1 of the present invention. When visualization is performed, in the transparent electrode 2 on the viewing side, electrons (e ⁻ ) are given from the transparent electrode 2 to silver ions (Ag ⁺ ) dissolved in the electrolyte 5, and silver (Ag) is converted into silver (Ag). It deposits on the transparent electrode 2 and usually produces a black image 4. At this time, on the counter electrode 3, electrons move from the silver (this silver does not exist at the beginning of the display element creation, but occurs at least once visualization → colorization) to the counter electrode 3. Then, silver ions (Ag ⁺ ) are released into the electrolyte 5.

  FIG. 1B shows a colorless reaction. In the transparent electrode 2 on the viewing side, electrons are received from silver, and silver is released into the electrolyte 5 as silver ions. On the counter electrode 3, electrons are given to the silver ions and precipitate as silver. For this reason, the slow reaction rate of the electron exchange on the counter electrode 3 is the limiting rate of the display speed. This is because when the carbon electrode is used as the counter electrode 3 for the purpose of durability of the electrode, the reaction rate of this electron exchange with respect to the transparent electrode 2 becomes slow. Display speed decreases.

  In the display element of the present invention, the reason why the display speed is improved by using a nitrogen-containing carbon electrode is that the exchange of electrons between silver or silver ions and the electrode is caused by the exchange of silver (Ag) with nitrogen ( It is presumed that Ag can rapidly undergo an oxidation-reduction reaction by binding to N) and forming an N-Ag bond.

  In a corresponding electrode having a nitrogen-containing carbon electrode layer that exhibits such an effect, nitrogen atoms are present in the electrode in at least one bonding form selected from the structural formulas [1] to [3]. Among these, the pyridine type represented by the structural formula [1] is particularly preferable. Nitrogen bonds can be analyzed by chemical bond state evaluation by XPS or the like. Below, an example of the chemical bond state calculated | required by XPS is shown.

(Porous structure)
In the display element of the present invention, it is preferable that nitrogen atoms are exposed on the surface of the nitrogen-containing carbon electrode layer from the viewpoint of further exerting the object effect of the present invention. A structure is preferred.

  The term “porous” as used in the present invention means that the nitrogen-containing carbon electrode layer has a large number of minute holes, and the surface area of the electrode is larger than the area where the electrode is provided. State. In order to make the effect of the present invention appear, it is not necessary that the hole penetrates to the substrate or the non-carbon-based electrode described later existing between the substrate and the nitrogen-containing carbon electrode layer.

(Method for producing electrode having nitrogen-containing carbon electrode layer and its raw material)
As a method for producing a nitrogen-containing carbon electrode layer according to the present invention, several methods can be mentioned as a method for incorporating nitrogen into the carbon electrode. For example, an electrode in which polyaminoquinoxaline particles are supported on carbon felt is disclosed in 1L30 of the 73rd Annual Meeting of the Electrochemical Society of Japan. Further, nitrogen can be doped into a general carbon electrode by a CVD method or a plasma method. In addition, a method of forming a complex of a nitrogen-containing heterocyclic hydrocarbon such as quinoline or pyridine with a template using mica as a template, treating it at a high temperature, and further removing the template is, for example, It is announced by the Technical Research Institute. A method for forming a crosslinked polymer gel from melamine and formaldehyde is disclosed in G. C. Rubin, R.A. W. Published by Pekara (J. Non-Cryst. Solids 186 (1995) 219), a carbon electrode having a porous structure can be obtained by firing this crosslinked polymer gel in a nitrogen atmosphere.

  Among the above-described methods for producing a nitrogen-containing carbon electrode layer, it is particularly preferable to prepare a nitrogen-containing carbon material, mix this with a conductive material and a binder, add a small amount of alcohol to form a paste, It is a method of applying on a carbon-based conductive layer and drying in a desiccator. Alternatively, when mixing a nitrogen-containing carbon material, a conductive material, and a binder, an appropriate amount of alcohol is added and strongly kneaded to obtain a sheet shape, which is obtained by a method of drying and then drying to obtain an appropriate thickness. Can do.

  The nitrogen-containing carbon material applicable by these methods is not particularly limited, but a carbon compound having a nitrogen-containing five-membered ring structure or a nitrogen-containing six-membered ring structure is preferable from the viewpoint that it can be efficiently formed. A compound represented by formula (1) or (2) is preferred.

  A nitrogen-containing carbon material can be easily obtained by heat-treating the compound represented by the general formula (1) or (2) at a high temperature of about 400 ° C. to 800 ° C. Note that the heat treatment is preferably performed in a nitrogen atmosphere in order to avoid bonding with oxygen.

  The conductive material can be selected from fine particles of metal or alloy, conductive carbon fine particles such as carbon black, graphite, graphitizable carbon, and non-graphitizable carbon.

  The conductive material is preferably used in the range of 0% by mass to 50% by mass of the nitrogen-containing carbon material. The conductivity increases as the amount of the conductive material increases, but in the display element of the present invention, the improvement in conductivity and the improvement in display speed do not necessarily correlate.

  Moreover, as a method of forming the nitrogen-containing carbon electrode layer having a porous structure according to the present invention, for example, the binder is 5% by mass to the total of the nitrogen-containing carbon material and the conductive material (total solid content). It is preferable to add in the range of 300% by mass. More preferably, it is the range of 5 mass%-100 mass%, More preferably, it is the range of 5 mass%-40 mass%. When the binder is added in an amount exceeding 300% by mass of the total solid content, the nitrogen-containing carbon material is buried in the binder, so that sufficient nitrogen is not exposed, and the object and effects of the present invention are sufficiently brought out. Hinder.

  As a binder applicable to the nitrogen-containing carbon electrode layer according to the present invention, natural rubber-based, cellulose-based, phenol-based, urethane-based, epoxy-based, fluorine-based resins, and the like can be used. Particularly preferred is polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / ethylene copolymer. Fluorine resins such as (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and chlorotrifluoroethylene-ethylene copolymer (ECTFE). These fluorine-based resins are preferable because they have a high effect of keeping the particles in a fibrous form and can be improved with a small amount of addition. In addition, it has excellent performance such as solvent resistance, chemical resistance and heat resistance.

  Among the methods for forming a nitrogen-containing carbon electrode layer having a porous structure according to the present invention described above, a nitrogen-containing carbon material, a binder, and a conductive material are mixed to form a paste and applied onto a desired substrate. This method is particularly preferable from the viewpoints of thickness control of the nitrogen-containing carbon electrode layer and ease of processing.

  The preferred thickness of the nitrogen-containing carbon electrode layer varies depending on the cell structure. When a non-carbon electrode is present between the nitrogen-containing carbon electrode layer and the substrate in contact with the nitrogen-containing carbon electrode, it is preferably about 5 to 100 nanometers (nm).

[Non-carbon electrode]
The display element of the present invention preferably has a configuration in which a non-carbon electrode is present in contact with the nitrogen-containing carbon electrode between the nitrogen-containing carbon electrode layer according to the present invention and the substrate. That is, since it is preferable that the nitrogen-containing carbon electrode is in contact with an electrolyte that dissolves silver, the non-carbon-based electrode is located on the substrate side from the nitrogen-containing carbon electrode layer, and further, the electron transfer efficiency between the electrodes is not hindered. The nitrogen-containing carbon electrode layer and the non-carbon electrode are preferably in contact with each other.

  Non-carbon electrode materials include, for example, metals such as platinum, gold, silver, rhodium, copper, chromium, and aluminum, semiconductors such as silicon and amorphous silicon, bismuth-silicon oxide, titanium oxide, and zinc oxide. , Metal oxides such as indium-tin-oxide, indium-zinc-oxide, and fluorine-doped tin oxide can be used. These may be used in combination.

  As a method for forming such an electrode, in addition to a plating method, a sputtering method, and the like, a method in which fine particles of these electrode forming materials are mixed with a binder and applied in a paste form is also possible. In particular, it is preferable that the non-carbon electrode has a conductive layer, and that the conductive layer contains silver from the viewpoint of efficient supply of silver to the electrolytic solution.

[Alkali metal ions]
In the display element of the present invention, a system in which the electrolyte does not substantially contain an alkali metal (ion) such as Li is preferable. If an alkali metal is present in the electrolyte, the alkali metal causes an electron exchange on the electrode instead of silver, thereby inhibiting image formation.

[Organic solvent]
In the display element of the present invention, the electrolyte preferably contains an organic solvent. An organic solvent is preferable because it can effectively dissolve a preferable electrolyte and has little risk of electrolysis or the like.

  As an organic solvent applicable to the present invention, various kinds of organic solvents can be used as long as the electrolyte can be dissolved, but a compound represented by the general formula (3) or (4) is more preferable.

  First, the compound represented by the general formula (3) according to the present invention will be described.

In the general formula (3), 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 (3) which concerns on this invention is shown, in this invention, it is not limited only to these illustrated compounds.

  Next, the compound represented by formula (4) according to the present invention will be described.

In the general formula (4), 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 (4) which concerns on this invention is shown, in this invention, it is not limited only to these illustrated compounds.

  Among the compounds represented by the general formulas (3) and (4) exemplified above, the exemplary compounds (3-1), (3-2), and (4-3) are particularly preferable.

  The compounds represented by the general formulas (3) and (4) according to the present invention are one kind of electrolyte solvents. However, in the display element of the present invention, another solvent is used as long as the object effects of the present invention are not impaired. Can be used together. 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.

  Furthermore, the display element of the present invention preferably contains at least one compound represented by the general formula (5) or (6).

In the general formula (5), R ₇ and R ₈ each represent a substituted or unsubstituted hydrocarbon group, which includes an aromatic straight chain 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 (5) which concerns on this invention is shown, in this invention, it is not limited only to these illustrated compounds.

5-1: CH ₃ SCH ₂ CH ₂ OH
5-2: HOCH ₂ CH ₂ SCH ₂ CH ₂ OH
5-3: HOCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OH
5-4: HOCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OH
5-5: HOCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ OH
5-6: HOCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OH
5-7: H ₃ CSCH ₂ CH ₂ COOH
5-8: HOOCCH ₂ SCH ₂ COOH
5-9: HOOCCH ₂ CH ₂ SCH ₂ CH ₂ COOH
5-10: HOOCCH ₂ SCH ₂ CH ₂ SCH ₂ COOH
5-11: HOOCCH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ COOH
_{5-12: HOOCCH 2 CH 2 SCH 2} CH 2 SCH 2 CH (OH) CH 2 SCH 2 CH 2 SCH 2 CH 2 COOH
5-13: 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
5-14: H ₃ CSCH ₂ CH ₂ CH ₂ NH ₂
5-15: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ NH ₂
5-16: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NH ₂
5-17: H ₃ CSCH ₂ CH ₂ CH (NH ₂ ) COOH
5-18: H ₂ NCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ NH ₂
5-19: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ NH ₂
5-20: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NH ₂
5-21: HOOC (NH ₂ ) CHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ CH (NH ₂ ) COOH
5-22: HOOC (NH ₂ ) CHCH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH (NH ₂ ) COOH
5-23: HOOC (NH ₂ ) CHCH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH (NH ₂ ) COOH
_{5-24: H 2 N (O =} ) CCH 2 SCH 2 CH 2 OCH 2 CH 2 OCH 2 CH 2 SCH 2 C (= O) NH 2
5-25: H ₂ N (O =) CCH ₂ SCH ₂ CH ₂ SCH ₂ C (O =) NH _{2
5-26: H 2 NHN (O =} ) CCH 2 SCH 2 CH 2 SCH 2 C (= O) NHNH 2
5-27: H ₃ C (O =) NHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NHC (O =) CH ₃
5-28: H ₂ NO ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SO ₂ NH ₂
5-29: NaO ₃ SCH ₂ CH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ CH ₂ SO ₃ Na
5-30: H ₃ CSO ₂ NHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NHO ₂ SCH ₃
5-31: H ₂ N (NH =) CSCH ₂ CH ₂ SC (NH) NH ₂ .2HBr
5-32: H ₂ N (NH =) CSCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SC (= NH) NH ₂ .2HCl
5-33: H ₂ N (NH═) CNHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NHC (═NH) NH ₂ .2HBr
5-34: [(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 5-2 is particularly preferable from the viewpoint that the object and effects of the present invention can be exhibited.

  Next, the compound represented by formula (6) according to the present invention will be described.

In the general formula (6), M represents a hydrogen atom, a metal atom, or quaternary ammonium. Z represents a nitrogen-containing heterocyclic ring excluding imidazole rings. n represents an integer of 0 to 5, and R ₄ 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 ₄ 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 (6) 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 (6) 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 ₄ in the general formula (6) 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 (6) is shown, this invention is not limited to these compounds.

  Among the above-exemplified compounds, Exemplified Compounds 6-12 and 6-18 are particularly preferable from the viewpoint that the object and effects of the present invention can be exhibited.

[Halogen ion or halogen atom concentration]
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.

[Electrolyte-silver salt]
In the display element of the present invention, silver iodide, silver chloride, silver bromide, silver oxide, silver sulfide, silver citrate, silver acetate, silver behenate, silver p-toluenesulfonate, silver salt with mercapto, iminodi A known silver salt compound such as a silver complex with acetic acid can be used. Among these, it is preferable to use, as a silver salt, a compound that does not have a nitrogen atom having coordination properties with halogen, carboxylic acid, or silver, and for example, silver p-toluenesulfonate is preferable.

  The silver ion concentration contained in the electrolyte layer 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 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 paragraph numbers [0062] to [0081] of JP-A-2003-187881 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 , Y ₂ O 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.

  Furthermore, it is preferable that the electrolyte contains a compound represented by the following general formula (A) from the viewpoint of further achieving the object effect of the present invention.

  In the general formula (A), X and Y each represent an alkyl group having 1 to 4 carbon atoms, and may be the same or different. k and i each represents 0 or a positive integer of 1 to 4, n and m each represents a positive integer of 3 to 7, and A represents an acid component.

  In general formula (A), when X and Y have 5 or more carbon atoms, k and i are 5 or more, or n and m are 8 or more, the ionic conductivity of the spiroammonium compound salt decreases, which is not preferable. .

  In the general formula (A), examples of the cation of the spiro ammonium compound salt include spiro- (1,1 ′)-biazacyclobutyl ion, azacyclopentane-1-spiro-1′-azacyclobutyl ion, and aza. Cyclohexane-1-spiro-1′-azacyclobutyl ion, azacycloheptane-1-spiro-1′-azacyclobutyl ion, azacyclooctane-1-spiro-1′-azacyclobutyl ion, spiro- (1 , 1 ')-biazacyclopentyl ion, azacyclohexane-1-spiro-1'-azacyclopentyl ion, azacycloheptane-1-spiro-1'-azacyclopentyl ion, azacyclooctane-1-spiro-1'- Azacyclopentyl ion, spiro- (1,1 ′)-biazacyclohexyl ion, a Cycloheptane-1-spiro-1′-azacyclohexyl ion, azacyclooctane-1-spiro-1′-azacyclohexyl ion, spiro- (1,1 ′)-biazacycloheptyl ion, azacyclooctane-1- Examples include spiro-1'-azacycloheptyl ion and spiro- (1,1 ')-biazacyclooctyl ion.

In the general formula (A), A represents an acid component. For example, perchlorate ion (ClO ₄ ⁻ ), fluorine ion (F ⁻ ), chlorine ion (Cl ⁻ ), bromine ion (Br ⁻ ), iodine ion ( I ⁻ ), hexafluorophosphate ion (PF ₆ ⁻ ), hexafluoroantimonate ion (SbF ₆ ⁻ ), tetrafluoroborate ion (BF ₄ ⁻ ), trifluoromethanesulfonate ion (CF ₃ SO ₃ ⁻ ), Trifluoroacetate ion (CF ₃ CO ₂ ⁻ ), bistrifluoromethanesulfonylimide ion ((CF ₃ SO ₂ ) ₂ N ⁻ ), perfluorobutane sulfonate ion (C ₄ F ₉ SO ₃ ⁻ ), tristrifluoromethanesulfonylmethy Doion ((CF ₃ SO ₂ ) ₃ C ⁻ ), dicyanamide ion ((CN) ₂ N ⁻ ) and the like.

  In the present invention, the spiro ammonium compound salt represented by the general formula (A) is obtained by the following production method.

  First, a dibromoalkane brominated at both ends is allowed to act on an azacycloalkane in the presence of potassium carbonate in an isopropyl alcohol solvent to obtain spiroammonium bromide, and then the bromide is desalted by electrodialysis in water or alcohol. To obtain a spiro ammonium hydroxide solution. Next, an equimolar amount of an acid component corresponding to A in the general formula (A) is added to the obtained spiroammonium hydroxide solution for neutralization reaction, followed by dehydration under reduced pressure. Spiroammonium compound salts can be obtained.

  A preferable addition amount of the compound represented by the general formula (A) to the electrolytic solution is 0.1% by mass or more and 10% by mass or less. If it is 0.1% by mass or more, the improvement effect of the present invention will be exhibited, and if it is 10% by mass or less, low-temperature precipitation in the electrolytic solution will not occur, and it should be present in the electrolyte in a stable state. Can do.

[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.

(White scattering layer)
In the display element of the present invention, since the non-browsing side electrode is a carbon electrode, when the electrolyte solution is transparent, the color of the carbon electrode itself is visible, which affects visibility. Therefore, it is necessary to mix in the electrolyte a white scattering material that does not substantially dissolve in the electrolyte solvent, or to form a porous white scattering layer containing the white scattering material on the viewing side from the carbon electrode.

  Examples of such white scattering materials 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 hydrogen phosphate. Magnesium, alkaline earth metal salts, talc, kaolin, zeolite, acidic clay, glass, etc., 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.

  Moreover, when forming a porous white scattering layer, it can be formed by applying and drying a water mixture of a water-soluble polymer that does not substantially dissolve in the electrolyte and the white scattering material.

Examples of water-soluble polymers that are substantially insoluble in the electrolyte solvent according to the present invention include proteins such as gelatin and gelatin derivatives or cellulose derivatives, natural compounds such as polysaccharides such as starch, gum arabic, dextran, pullulan and carrageenan, , Synthetic polymer compounds such as polyvinyl alcohol, polyvinyl pyrrolidone, acrylamide polymers and derivatives thereof. Examples of gelatin derivatives include acetylated gelatin, phthalated gelatin, polyvinyl alcohol derivatives include terminal alkyl-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 (e.g., sodium methacrylate in the vinyl monomer having a methacrylic acid Copolymers with ammonium, potassium acrylate, etc.) are also used. Two or more of these binders can be used in combination.

  In the present invention, gelatin and gelatin derivatives, or polyvinyl alcohol or derivatives thereof can be preferably used.

  In the present invention, “substantially insoluble in an electrolyte solvent” is defined as a state in which the dissolved amount per kg of electrolyte solvent is 0 g or more and 10 g or less at a temperature of −20 ° C. to 120 ° C. The amount of dissolution can be determined by a known method such as a component determination method using a chromatogram or a gas chromatogram.

  The water mixture of the water-soluble polymer and the white pigment according to the present invention preferably has a form in which the white pigment is dispersed in water according to a known dispersion method. The volume ratio of the water-soluble polymer / white pigment mixing ratio is preferably 1 to 0.01, and more preferably 0.3 to 0.05.

  The medium for applying the water mixture of the water-soluble polymer and the white pigment according to the present invention may be at any position as long as it is on the component between the counter electrodes of the display element, but at least one of the counter electrodes. It is preferable to apply on the surface. As a method for applying to a medium, for example, a coating method, a liquid spraying method, a spraying method via a gas phase, a method of flying droplets using vibration of a piezoelectric element, for example, a piezoelectric inkjet head, Examples thereof include a bubble jet (registered trademark) type ink jet head that causes droplets to fly using a thermal head that uses bumping, and a spray type that sprays liquid by air pressure or liquid pressure.

  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.

  The water mixture of the water-soluble polymer and the white pigment applied on the medium according to the present invention may be dried by any method as long as water 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. Further, water evaporation may be performed under reduced pressure.

  In the display element of the present invention, it is preferable that a curing reaction of the water-soluble polymer is performed with a curing agent during or after coating and drying the water admixture described above.

  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 water-soluble polymer, 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 water-soluble polymer.

[Other additives for electrolyte layer]
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
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. Also preferred are syndiotactic polystyrenes. 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.

[Transparent electrode]
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, and the like can be given.

  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.

[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.

  The sealing agent is used to seal the electrolyte so that it does not leak out. It is also called a sealing agent. Epoxy resin, urethane resin, acrylic resin, vinyl acetate resin, ene-thiol resin, silicone resin A curing type such as a thermosetting type, a photo-curing type, a moisture-curing type, or an anaerobic curing type such as a modified polymer resin 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 maintain an appropriate interval between substrates, 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 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 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 estimated 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 advantages such as gradation and a 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 electrode>
(Production of electrode 1: comparative example)
A silver-palladium electrode having an electrode thickness of 0.8 μm, a pitch of 145 μm, and an electrode width of 130 μm was produced on a glass substrate using a known method.

(Production of electrode 2: comparative example)
Activated carbon, ketjen black, and polytetrafluoroethylene (PTFE) were mixed at a mass ratio of 8: 1: 1 while dropwise in ethanol. When the whole is well mixed and pasty, it is coated on a glass substrate with a thickness of 75 nm, an electrode pitch of 145 μm, and an electrode width of 130 μm, and dried in a desiccator. An electrode 2 was produced.

(Preparation of electrode 3: the present invention)
The electrode 2 produced above was immersed in a polyaminoquinoxaline solution, which was pulled up and dried to produce an electrode 3 that is a nitrogen-containing carbon electrode with polyaminoquinoxaline added to the electrode surface.

(Preparation of electrode 4: the present invention)
The above-prepared electrode 2 is mounted on a sample portion 101 in a plasma container 100 as shown in FIG. 2 and a high-frequency antenna 104 is formed by a heating body 103 connected to a temperature controller 102 under a nitrogen atmosphere and a pressure of 133 Pa. The electrode 4 which is a nitrogen-containing carbon electrode was produced by performing a plasma treatment for 30 minutes in a state heated to 150 ° C.

(Preparation of electrode 5: the present invention)
G. C. Melamine-formamide aerogels were prepared according to the literature of Rubin et al. (J. Non-Cryst. Solids 186 (1995) 219). This airgel was baked at 900 ° C. for 1 hour under a nitrogen atmosphere to form a melamine-formaldehyde carbon aerogel, and an electrode 5 which is a nitrogen-containing carbon electrode was produced. (Example)
(Preparation of electrode 6: the present invention)
By treating 2,3,6,7-tetracyano-1,4,5,8-tetraazonaphthalene in a nitrogen atmosphere at 800 ° C. for 1 hour, a nitrogen-containing carbon material was obtained. This nitrogen-containing carbon material and ketjen black, which is conductive carbon, and PTFE resin were mixed and processed in the same manner as in the electrode 2 at a mass ratio of 8: 1: 1 to produce an electrode 6 that is a nitrogen-containing carbon electrode.

(Production of electrode 7: comparative example)
The paste used in the production of the electrode 2 was applied on the silver-palladium electrode as the electrode 1 by masking so that the electrode positions were aligned to a thickness of 75 nm, an electrode pitch of 150 μm, and an electrode width of 125 μm, and in a desiccator The electrode 7 which made it dry and formed the porous carbon electrode on the silver electrode was produced.

(Preparation of electrode 8: the present invention)
In the production of the electrode 7, a porous carbon electrode portion was dipped in a polyaminoquinoxaline solution, pulled up and dried, and similarly, a nitrogen-containing carbon electrode provided with polyaminoquinoxaline on the electrode surface. An electrode 8 was produced.

(Preparation of electrode 9: the present invention)
The nitrogen-containing carbon electrode paste used for the production of the electrode 6 was applied and processed on the electrode 1 in the same manner as the electrode 3 to produce an electrode 8 which is a nitrogen-containing carbon electrode.

(Electrode 10: Production of transparent electrode)
An ITO film having a thickness of 1.5 mm and a 2 cm × 4 cm glass substrate with a pitch of 145 μm and an electrode width of 130 μm was formed according to a known method to obtain a transparent electrode (electrode 1).

<< Preparation of electrolyte solution >>
(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 300 mg of titanium oxide (average primary particle size 0.37 μm) was added and the oxidation was performed using an ultrasonic disperser. Titanium was dispersed, 150 mg of polyvinyl pyrrolidone (average molecular weight 15000) was further added, and the mixture was stirred for 1 hour while heating at 120 ° C. to obtain an electrolyte solution 1.

<< Production of display element >>
Electrolyte solution 1 is dropped on electrodes 1 to 9 that are edged with an olefin-based sealant containing 10% by volume of glass spherical beads having an average particle diameter of 70 μm at the periphery, and electrodes 10 are connected to each other from above. Were arranged so as to face each other and pressed with a pressure of 9.8 kPa to produce display elements 1 to 9. However, the display element 5 has a glass substrate attached to the back surface of the electrode 7.

<< Evaluation of display element >>
The following evaluation was performed about each produced said 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 repeated durability)
About the produced said display elements 1, 3-6, 8, and 9, repeated durability evaluation was performed in accordance with the following method.

  For each display element, after obtaining a driving condition such that the reflectance at 550 nm of a spectrophotometer CM-3700d manufactured by Konica Minolta Sensing Co., Ltd. is 10%, whitening and blackening are driven 1000 times under the driving condition. I let you.

  Thereafter, the blackening was performed again, and a blackened image of 300 pixels squared was picked up with a CCD camera, and the number of stripe electrodes having an electrode width of 3/4 or less (including disconnection) was counted. The evaluation value and the number of deterioration are: 10 is no deterioration, 9 is 1 to 5, 8 is 6 to 10, 7 is 11 to 15, 6 is 16 to 20, 5 is 21 to 25, 4 is 26 -30, 3 is 31 to 35, 2 is 36 to 40, 1 is 41 or more, and the higher the evaluation value, the better the electrode durability.

(Measurement of electrode nitrogen content)
About the produced electrodes 3-6, the composition analysis by a combustion method was performed and nitrogen content was computed.

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

  As is apparent from the results shown in Table 1, it can be seen that the display element of the present invention having a nitrogen-containing carbon electrode has a higher display speed and superior electrode repetition durability than the comparative example.

  Moreover, as a result of measuring the nitrogen-carbon chemical bond state by XPS N1s spectrum analysis about the electrodes 3-6, the peak of quaternary nitrogen and the pyridine type nitrogen was recognized by each electrode. The obtained spectrum is shown in FIG.

  Note that the order of the spectral intensity on the vertical axis of each electrode in FIG. 3 is not particularly significant, and the spectra of four electrodes are arranged vertically for convenience.

It is a conceptual diagram explaining the principle of the display element of this invention. It is the schematic of the plasma processing apparatus used in the Example. It is the spectrum which measured the chemical bond state of nitrogen-carbon by XPS N1s spectrum analysis.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display element 2 Transparent electrode 3 Counter electrode 4 Black image (silver image)
DESCRIPTION OF SYMBOLS 5 Electrolyte 100 Plasma processing container 101 Sample part 102 Temperature controller 103 Heating body 104 High frequency antenna

Claims (11)

A display element having an electrolyte 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, At least one is an electrode having a nitrogen-containing carbon electrode layer. The display element according to claim 1, wherein the nitrogen-containing carbon electrode layer has a porous structure. The nitrogen atom contained in the nitrogen-containing carbon electrode layer is contained in at least one bonding form selected from the following structural formulas [1], [2] and [3]. The display element as described.

The nitrogen-containing carbon material forming the nitrogen-containing carbon electrode layer is formed from a carbon compound having a nitrogen-containing five-membered ring structure or a nitrogen-containing six-membered ring structure. The display element according to item. The display device according to claim 4, wherein the carbon compound having the nitrogen-containing five-membered ring structure or the nitrogen-containing six-membered ring structure is a compound represented by the following general formula (1) or (2). .

[Wherein R ^{1 to} R ⁷ are each a cyano group, an amino group, an imino group, an N-oxide, a hydroxyamino group, a nitro group, a nitroso group, an azo group, a diazo group, an azide group, an alkyl group, and At least one selected from the induced bonds, and each may be the same or different. ] 6. The non-carbon-based electrode is present in contact with the nitrogen-containing carbon electrode between the nitrogen-containing carbon electrode layer and the substrate. Display element. The display element according to claim 6, wherein the non-carbon electrode has a conductive layer, and the conductive layer contains silver. The display element according to claim 1, wherein the electrolyte contains substantially no alkali metal. The display element according to claim 1, wherein the electrolyte contains an organic solvent. The electrolyte contains at least one compound represented by the following general formula (3) or (4) and at least one compound represented by the following general formula (5) or (6). The display element according to claim 1, wherein the display element is a display element.

[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 (5)
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. ] The molar concentration of halogen ions or halogen atoms contained in the electrolyte is [X] (mol / kg), and the total molar concentration of silver contained in the electrolyte or the compound containing silver in the chemical structure is [Ag] ( The display element according to any one of claims 1 to 10, wherein a condition defined by the following formula (1) is satisfied:
Formula (1)
0 ≦ [X] / [Ag] ≦ 0.01

Images