JP5347516B2 - Method for manufacturing electrochemical display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display element which has a simple member constitution, can be driven by a low voltage and has a small change in characteristics during repeated driving. <P>SOLUTION: A method for producing the electrochemical display element, which has an electrolytic solution containing at least a silver salt compound between a pair of counter electrodes disposed respectively on an observation side and on a non-observation side, has the steps of: depositing a silver thin film 5 on at least one of the pair of counter electrodes; and applying an electric field between the pair of counter electrodes to form deposited silver 7, 8 on the electrode opposed to the silver thin film-deposited electrode while dissolving the silver thin film. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a novel electrochemical display element.

  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 to compensate for these drawbacks, a reflection type display using so-called "memory" that uses external light and does not consume power for image retention is known. However, it has sufficient performance for the following reasons. It is hard to say that it has.

  That is, the method using a polarizing plate such as a reflective liquid crystal has a low reflectance of about 40%, which makes it difficult to display white, and it is difficult to say that many of the manufacturing methods used to manufacture the constituent members are simple. 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 driving 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.

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

  As a result of examining the techniques disclosed in each of the above patent documents in detail, the present inventor has found that there is a problem in the stability of the reflectance when it is repeatedly driven, and solves this problem. As a means for improving the electrolysis driving stability of the metal dissolution precipitation type electrochemical display element, there is a technique of adding a redox buffer such as ferrocene to the electrolytic solution as in Patent Document 4. Although this technology is intended to improve driving stability by redox buffer oxidation / reduction at the non-observation side electrode, it is necessary to increase the amount of redox buffer sufficiently to improve driving stability. In this case, it was found that there was a decrease in memory performance and a decrease in rewriting speed.

  Further, in Patent Document 5 and Patent Document 6, the use of a silver electrode or an electrode containing silver particles as the non-observation side electrode suppresses fluctuations in overvoltage of silver dissolution and precipitation reaction at the observation side electrode, thereby stabilizing the drive. Although it is effective when the number of repeated driving is small, the dissolution reaction of the silver electrode on the non-observation side itself is displayed when displaying black when the number of repeated driving is increased. As a result, it has been found that there is a problem that the driving stability is lowered.

  In addition, as another technique, Patent Document 7 includes a technique in which an electrolyte is sealed between counter electrodes and then the electrode on the non-observation side is silver-plated in advance using the electrolyte as a silver plating solution. As a result of undesirable oxidation reaction of the electrolyte on the observation side electrode in the step of silver plating on the side electrode, it was found that the driving stability becomes unstable due to the change in the composition of the electrolyte.

U.S. Pat. No. 4,240,716 Japanese Patent No. 3428603 JP 2003-241227 A JP 2007-508587 A JP-A-2005-283986 JP-A-10-274790 International Publication No. 07/058063 Pamphlet

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a display element that has a simple member configuration, can be driven at a low voltage, and has few characteristic changes in repeated driving.

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

  1. In an electrochemical display element having an electrolytic solution containing at least a silver salt compound between a pair of counter electrodes configured on the observation side and the non-observation side, a silver thin film is formed in advance on at least one of the pair of counter electrodes An electrochemical display element comprising: a step of forming precipitated silver on an electrode opposite to an electrode on which the silver thin film is formed while applying an electric field between the counter electrodes to dissolve the silver thin film Production method.

  2. A method for producing the electrochemical display device according to 1 above, wherein a step of forming a silver thin film on the observation side electrode in advance, a step of making the observation side electrode and the non-observation side electrode face each other, and between the facing electrodes A step of filling the electrode with an electrolyte solution, applying a voltage between the electrodes so that the observation side electrode becomes noble, reducing the silver compound in the electrolyte solution while dissolving the silver thin film on the observation side, and the non-observation side electrode 2. The method for producing an electrochemical display element as described in 1 above, further comprising a step of forming precipitated silver on the top.

  3. 2. A method for producing the electrochemical display device according to 1 above, wherein a step of forming a silver thin film in advance on the non-observation side electrode, a step of facing the non-observation side electrode and the observation side electrode, and between the facing electrodes A step of filling the electrolyte solution with a silver compound in the electrolyte solution on the observation side electrode while applying a voltage between the counter electrodes so that the observation side electrode becomes base and dissolving the silver thin film on the non-observation side Step of reducing and forming precipitated silver, reducing the silver compound in the electrolytic solution while applying a voltage between a pair of electrodes so that the observation side electrode becomes noble and dissolving the precipitation silver on the observation side 2. The method for producing an electrochemical display element as described in 1 above, further comprising a step of forming precipitated silver on the non-observation side electrode.

  4). 4. The method for producing an electrochemical display element according to any one of 1 to 3, wherein the silver purity in the silver thin film is 99% or more and 100% or less.

  5. 5. The method for producing an electrochemical display element according to any one of 1 to 4, wherein the silver thin film is formed by a sputtering method.

  6). 6. The method for producing an electrochemical display element according to any one of 1 to 5, wherein the silver thin film has a thickness of 5 nm to 50 nm.

  7). The method for producing an electrochemical display element according to any one of 1 to 6, wherein a voltage applied between the counter electrodes is 0.5 V or more and 1.2 V or less.

  According to the present invention, it is possible to provide a display element that can be driven with a simple member configuration, a low voltage, and has little characteristic change in repeated driving.

A method for forming an electrochemical display element by forming a silver thin film on an observation side electrode will be described. A method for forming an electrochemical display element by forming a silver thin film on a non-observation side electrode will be described.

  The present inventor has found that the drive stability of the display element can be improved by forming a deposited silver layer on the non-observation side electrode before forming an image on the display element. Further, the deposited silver layer is deposited from an electrolytic solution, and in order to stabilize the concentration of the silver salt compound in the electrolytic solution, a silver thin film is formed in advance on at least one of the counter electrodes. It is effective to apply a voltage between the electrodes to oxidize and dissolve the silver thin film, and at the same time, the silver salt compound in the electrolytic solution is reduced to form precipitated silver on the electrode opposite to the electrode having the silver thin film. I found out.

  Details of the present invention will be described below.

[Basic structure of display element]
In the display element of the present invention, the display portion is provided with a corresponding pair of counter electrodes.

  A transparent electrode such as an ITO electrode is provided on the observation side electrode which is one of the counter electrodes.

  The precipitated silver in the present invention refers to the silver deposited by reducing the silver salt compound contained in the electrolytic solution, and the silver film formed by screen printing application of silver paste, ink jet of silver ink or the like. Different.

  An example of the method for forming precipitated silver according to the present invention will be described below.

  The silver thin film of the present invention may be provided on the observation-side electrode or on the non-observation-side electrode. The silver thin film is dissolved while the silver thin film is dissolved by applying a voltage between the counter electrodes so that the potential on the electrode side provided with the silver thin film becomes noble after filling the electrolyte containing the silver salt compound between the counter electrodes Deposited silver can be formed by reducing the silver salt compound in the electrolytic solution on the electrode side opposite to the electrode provided with. When the electrode on the side on which the deposited silver is formed is the electrode on the observation side, by further applying a voltage between the counter electrodes so that the electrode on the observation side becomes noble, while dissolving the deposited silver on the electrode on the observation side Precipitated silver can be formed by reducing the silver salt compound in the electrolyte on the non-observed electrode side. In any case, it is possible to provide a display element in which a sufficient amount of precipitated silver is formed on the non-observation side electrode without changing the composition of the electrolytic solution before shipment.

[Silver thin film]
The silver thin film of the present invention can be formed by sputtering, vapor deposition, printing, ink jet, or the like. However, the silver thin film of the present invention excludes precipitated silver using an electrolytic solution. In the present invention, a preferred forming method is a sputtering method. The silver thin film of the present invention may be provided on the observation side electrode or on the non-observation side electrode. However, before shipping, the silver thin film is substantially completely dissolved and deposited on the non-observation side electrode. It is characterized by forming. The state of the display element at the time of shipment is characterized in that there is no silver thin film or precipitated silver on the observation side electrode, and precipitated silver is formed on the non-observation side electrode.

  The purity of silver in the silver thin film is preferably 99% or more and 100% or less. This is to avoid performance fluctuations due to impurities in the silver thin film remaining on the electrode or eluting into the electrolyte.

  Since the amount of precipitated silver on the non-observation side electrode depends on the film thickness of the silver thin film, the film thickness of the silver thin film is preferably 5 nm or more and 50 nm or less. The applied voltage when the silver thin film is melted by applying a voltage between the counter electrodes is preferably 0.6 V or more and 1.2 V or less. This is because if the applied voltage is too low, the time required to dissolve the silver thin film becomes long, and if the applied voltage is too high, an undesirable decomposition reaction of the components of the electrolytic solution may occur.

  The manufacturing method of the electrochemical display element of this invention is demonstrated using figures.

  FIG. 1 shows a method of forming an electrochemical display element by forming a silver thin film on an observation side electrode.

  In FIG. 1A, a silver thin film 5 is formed on the observation side electrode 2 by sputtering. In FIG. 1B, the observation side electrode 2 and the non-observation side electrode 4 on which the silver thin film 5 is formed are opposed to each other. In FIG. 1 (c), an electrolytic solution 6 containing a silver salt compound is filled between the opposing electrodes, and in FIG. 1 (d), a voltage is applied so that the observation side electrode 2 becomes +1.2 V, and observation is performed. The silver thin film 5 formed on the side is completely dissolved, and precipitated silver 7 is formed on the non-observation side electrode 4, and is shipped as a final product in FIG. 1 (e).

  On the other hand, FIG. 2 shows a method of forming an electrochemical display element by forming a silver thin film on the non-observation side electrode.

  2A, a silver thin film 5 is formed on the non-observation side electrode 4 by sputtering. In FIG. 2B, the non-observation side electrode 4 and the observation side electrode 2 on which the silver thin film 5 is formed are opposed to each other. 2 (c), an electrolyte solution 6 containing a silver salt compound is filled between the opposing electrodes, and in FIG. 2 (d), a voltage is applied so that the observation side electrode 2 is −1.2V. The silver thin film 5 formed on the non-observation side is completely dissolved to form precipitated silver 7 on the observation-side electrode 2, and the observation-side electrode 2 becomes +1.2 V in FIG. 2 (e). As shown in FIG. 2F, the deposited silver 7 formed on the observation side is completely dissolved, and the precipitated silver 8 is formed on the non-observation side electrode 4, and is shipped as a final product. .

  Hereinafter, other configurations that can be used in the electrochemical display element of the present invention will be described.

[Silver salt compound]
The silver salt compound according to the present invention is silver or a compound containing silver in the chemical structure, such as silver oxide, silver sulfide, metallic silver, silver colloidal particles, silver halide, silver complex compound, silver ion and the like. There are no particular restrictions on the phase state species such as the solid state, the solubilized state in liquid, and the gas state, and the charged state species such as neutral, anionic, and cationic.

  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 trifluoromethanesulfonate, mercapto A known silver salt compound such as a silver salt with an acid or a silver complex with iminodiacetic 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 metal ion concentration contained in the electrolyte according to the present invention is preferably 0.2 mol / kg ≦ [Metal] ≦ 2.0 mol / kg. If the metal ion concentration is 0.2 mol / kg or more, a silver solution with a sufficient concentration can be obtained, and a desired driving speed can be obtained. If the metal ion concentration is 2 mol / kg or less, precipitation is prevented, The stability of the electrolyte solution is improved.

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

Formula (1): 0 ≦ [X] / [Metal] ≦ 0.1
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] / [Metal] is greater than 0.1, X ⁻ → X ₂ is generated during the oxidation-reduction reaction of the metal, and X ₂ easily cross-oxidizes with the deposited metal to dissolve the deposited metal. Therefore, the molar concentration of halogen atoms is preferably as low as possible relative to the molar concentration of metallic silver. In the present invention, 0 ≦ [X] / [Metal] ≦ 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.

[Compound represented by General Formula (G1) or (G2)]
In the present invention, a silver salt solvent can be used to promote dissolution and precipitation of metal salts (particularly silver salts). The silver salt solvent may be any compound that can solubilize silver in the 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 supply bond with silver. It is common to use a means for converting to an object. As the chemical species, halogen atoms, mercapto groups, carboxyl groups, imino groups and the like are known, but in the present invention, compounds containing thioether groups and mercaptoazoles are useful as silver solvents, and It is characterized by low influence on coexisting compounds and high solubility in solvents.

  In particular, it is preferable to contain at least one compound represented by the following general formula (G1) or general formula (G2).

[Compound represented by General Formula (G1) or General Formula (G2)]
General Formula _{(G1) Rg 11 -S-Rg} 12
[Wherein, Rg ₁₁ and Rg ₁₂ each represent a substituted or unsubstituted hydrocarbon group. These hydrocarbon groups may contain one or more nitrogen atoms, oxygen atoms, phosphorus atoms, sulfur atoms, and halogen atoms, and Rg ₁₁ and Rg ₁₂ may be linked to each other to form a cyclic structure. ]

[Wherein, M represents a hydrogen atom, a metal atom or quaternary ammonium. Z represents an atomic group necessary for constituting a nitrogen-containing heterocyclic ring. n represents an integer of 0 to 5, Rg ₂₁ represents a substituent, and when n is 2 or more, each Rg ₂₁ may be the same or different, and may be connected to each other to form a condensed ring. It may be formed. ]
In the general formula (G1), Rg ₁₁ and Rg ₁₂ 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, and sulfur atoms, and Rg ₁₁ and Rg ₁₂ may be connected to each other to take a cyclic structure. 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.

  Hereinafter, specific examples of the compound represented by the general formula (G1) according to the present invention will be shown, but the present invention is not limited only to these exemplified compounds.

G1-1: CH ₃ SCH ₂ CH ₂ OH
G1-2: HOCH ₂ CH ₂ SCH ₂ CH ₂ OH
G1-3: HOCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OH
G1-4: HOCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OH
G1-5: HOCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ OH
_{G1-6: HOCH 2 CH 2 OCH 2} CH 2 SCH 2 CH 2S CH 2 CH 2 OCH 2 CH 2 OH
G1-7: H ₃ CSCH ₂ CH ₂ COOH
G1-8: HOOCCH ₂ SCH ₂ COOH
G1-9: HOOCCH ₂ CH ₂ SCH ₂ CH ₂ COOH
G1-10: HOOCCH ₂ SCH ₂ CH ₂ SCH ₂ COOH
G1-11: HOOCCH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ COOH
G1-12: HOOCCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH (OH) CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ COOH
G1-13: 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
G1-14: H ₃ CSCH ₂ CH ₂ CH ₂ NH ₂
G1-15: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ NH ₂
G1-16: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NH ₂
G1-17: H ₃ CSCH ₂ CH ₂ CH (NH ₂ ) COOH
G1-18: H ₂ NCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ NH _{2
G1-19: H 2 NCH 2 CH 2} SCH 2 CH 2 OCH 2 CH 2 OCH 2 CH 2 SCH 2 CH 2 NH 2
G1-20: H ₂ NCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NH ₂
G1-21: HOOC (NH ₂ ) CHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ CH (NH ₂ ) COOH
G1-22: HOOC (NH ₂ ) CHCH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ SCH ₂ CH (NH ₂ ) COOH
G1-23: HOOC (NH ₂ ) CHCH ₂ OCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH (NH ₂ ) COOH
_{G1-24: H 2 N (O =} ) CCH 2 SCH 2 CH 2 OCH 2 CH 2 OCH 2 CH 2 SCH 2 C (= O) NH 2
_{G1-25: H 2 N (O =} ) CCH 2 SCH 2 CH 2 SCH 2 C (= O) NH 2
_{G1-26: H 2 NHN (O =} ) CCH 2 SCH 2 CH 2 SCH 2 C (= O) NHNH 2
_{G1-27: H 3 C (O =} ) CNHCH 2 CH 2 SCH 2 CH 2 SCH 2 CH 2 NHC (= O) CH 3
_{G1-28: H 2 NO 2 SCH 2} CH 2 SCH 2 CH 2 SCH 2 CH 2 SO 2 NH 2
_{G1-29: NaO 3 SCH 2 CH 2} CH 2 SCH 2 CH 2 SCH 2 CH 2 CH 2 SO 3 Na
G1-30: H ₃ CSO ₂ NHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NHO ₂ SCH ₃
G1-31: H ₂ N (NH) CSCH ₂ CH ₂ SC (NH) NH ₂ .2HBr
_{G1-32: H 2 N (NH)} CSCH 2 CH 2 OCH 2 CH 2 OCH 2 CH 2 SC (NH) NH 2 · 2HCl
G1-33: H ₂ N (NH) CNHCH ₂ CH ₂ SCH ₂ CH ₂ SCH ₂ CH ₂ NHC (NH) NH ₂ .2HBr
G1-34: [(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 G1-2 is particularly preferable from the viewpoint that the object and effects of the present invention can be exhibited.

  Next, the compound represented by formula (G2) according to the present invention will be described.

In the general formula (G2), 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, Rg ₂₁ represents a substituent, and when n is 2 or more, each Rg ₂₁ may be the same or different, and may be connected to each other to form a condensed ring. It may be formed.

Examples of the metal atom represented by M in the general formula (G2) 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 having Z as a constituent in the general formula (G2) include, for example, 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.

The substituents represented by Rg ₂₁ of the general formula (G2), not particularly limited, but include for example substituents such as the following.

  Hydrogen atom, halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom), alkyl group (eg, methyl, ethyl, propyl, i-propyl, butyl, t-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl) Octyl, dodecyl, hydroxyethyl, methoxyethyl, trifluoromethyl, benzyl, etc.), aryl groups (eg, phenyl, naphthyl, etc.), alkylcarbonamide groups (eg, acetylamino, propionylamino, butyroylamino, etc.), aryl Carboxamide groups (eg, benzoylamino), alkylsulfonamide groups (eg, methanesulfonylamino group, ethanesulfonylamino group, etc.), arylsulfonamide groups (eg, benzenesulfonylamino group, toluenesulfonylamino) Group), alkoxy group, aryloxy group (for example, phenoxy), alkylthio group (for example, methylthio, ethylthio, butylthio, etc.), arylthio group (for example, phenylthio group, tolylthio group, etc.), alkylcarbamoyl group (for example, methylcarbamoyl group) Dimethylcarbamoyl, ethylcarbamoyl, diethylcarbamoyl, dibutylcarbamoyl, piperidylcarbamoyl, morpholylcarbamoyl, etc.), arylcarbamoyl groups (eg, phenylcarbamoyl, methylphenylcarbamoyl, ethylphenylcarbamoyl, benzylphenylcarbamoyl, etc.), carbamoyl groups, alkylsulfurates Famoyl groups (eg methylsulfamoyl, dimethylsulfamoyl, ethylsulfamoyl, diethylsulfamoyl, dibu Sulfamoyl, piperidylsulfamoyl, morpholylsulfamoyl, etc.), arylsulfamoyl groups (eg, phenylsulfamoyl, methylphenylsulfamoyl, ethylphenylsulfamoyl, benzylphenylsulfamoyl, etc.), sulfamoyl groups , Cyano group, alkylsulfonyl group (for example, methanesulfonyl group, ethanesulfonyl group, etc.), arylsulfonyl group (for example, phenylsulfonyl, 4-chlorophenylsulfonyl, p-toluenesulfonyl, etc.), alkoxycarbonyl group (for example, methoxycarbonyl, Ethoxycarbonyl, butoxycarbonyl etc.), aryloxycarbonyl group (eg phenoxycarbonyl etc.), alkylcarbonyl group (eg acetyl, propionyl, butyroyl etc.), a A reelcarbonyl group (for example, benzoyl group, alkylbenzoyl group, etc.), an acyloxy group (for example, acetyloxy, propionyloxy, butyroyloxy, etc.), a carboxyl group, a carbonyl group, a sulfonyl group, an amino group, a hydroxy group, or a heterocyclic group (for example, , Oxazole ring, thiazole ring, triazole ring, selenazole ring, tetrazole ring, oxadiazole ring, thiadiazole ring, thiazine ring, triazine ring, benzoxazole ring, benzthiazole ring, indolenine ring, benzselenazole ring, naphthothiazole ring , Triazaindolizine ring, diazaindolizine ring, tetraazaindolizine ring group, etc.). These substituents further include those having a substituent.

  Next, although the preferable specific example of a compound represented by general formula (G2) is shown, this invention is not limited to these compounds.

  Among the above-exemplified compounds, Exemplified Compounds G2-12 and G2-18 are particularly preferable from the viewpoint that the object and effects of the present invention can be exhibited.

〔solvent〕
Solvents are generally used in electrochemical cells and batteries, and dissolve various additives such as electrochromic compounds used in the present invention, metal salt compounds that are reversibly dissolved and precipitated by electrochemical redox reactions, and promoters. Any solvent can be used.

  Specifically, acetic anhydride, methanol, ethanol, tetrahydrofuran, ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, butylene carbonate, propylene carbonate, nitromethane, acetonitrile, acetylacetone, N-methylformamide, N, N-dimethylformamide , Dimethyl sulfoxide, hexamethylphosphoamide, dimethoxyethane, diethoxyfuran, γ-butyrolactone, γ-valerolactone, sulfolane, propionitrile, butyronitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, N-methylacetamide, N, N -Dimethylacetamide, N-methylpropionamide, methylpyrrolidinone, 2- (N-methyl) -2-pyrrolidi Non, dimethyl sulfoxide, dioxolane, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, ethyl dimethyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, tris ( Trifluoromethyl) phosphate, tris (pentafluoroethyl) phosphate, triphenyl phosphate, tricresyl phosphate, 2-ethylhexyl phosphate, tetramethylurea, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphotriamide, 4-methyl-2-pentanone, dioctyl phthalate, dioctyl sebacate, and ethylene glycol Lumpur, diethylene glycol, polyethylene glycols such as triethylene glycol monobutyl ether and the like can be used.

  Furthermore, room temperature molten salts can also be used as solvents. The room temperature molten salt is a salt composed of ion pairs that are melted at room temperature (that is, in a liquid state) consisting only of ion pairs that do not contain a solvent component, and usually has a melting point of 20 ° C. or lower, A salt consisting of an ion pair that is liquid at a temperature above. The room temperature molten salt can be used alone or in combination of two or more.

  The solvent used in the present invention is preferably an aprotic polar solvent, particularly propylene carbonate, ethylene carbonate, dimethyl sulfoxide, dimethoxyethane, acetonitrile, γ-butyrolactone, sulfolane, dioxolane, dimethylformamide, dimethoxyethane, tetrahydrofuran, adiponitrile, methoxy. Acetonitrile, dimethylacetamide, methyl pyrrolidinone, dimethyl sulfoxide, dioxolane, sulfolane, trimethyl phosphate and triethyl phosphate are preferred. The solvent may be used alone or in combination of two or more.

  In the present invention, particularly preferably used solvents are compounds represented by the following general formulas (S1) and (S2).

[Compounds Represented by General Formulas (S1) and (S2)]
In the display element of the present invention, the electrolyte preferably contains a compound represented by the following general formula (S1) or (S2).

In the formula, L represents an oxygen atom or an alkylene group, and Rs ₁₁ to Rs ₁₄ each represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group, or an alkoxy group.

In the formula, Rs ₂₁ and Rs ₂₂ each represents an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group, or an alkoxy group.

  First, the detail of the compound represented by general formula (S1) is demonstrated.

In the general formula (S1), L represents an oxygen atom or CH ₂ , and Rs ₁₁ to Rs ₁₄ each represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group, or an alkoxy group, These substituents may be further substituted with an arbitrary substituent.

  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 (S1) is shown, in this invention, it is not limited only to these illustrated compounds.

  Next, details of the compound represented by formula (S2) according to the present invention will be described.

In the general formula (S2), Rs ₂₁ and Rs ₂₂ 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 (S2) is shown, in this invention, it is not limited only to these illustrated compounds.

  Of the compounds represented by the general formulas (S1) and (S2) exemplified above, the exemplary compounds (S1-1), (S1-2), and (S2-3) are particularly preferable.

  The compounds represented by the general formulas (S1) and (S2) according to the present invention are one type of electrolyte solvent. 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.

(Porous white scattering layer)
In the present invention, a porous white scattering layer can be provided from the viewpoint of further enhancing display contrast and white display reflectance.

  The porous white scattering layer applicable to the present invention can be formed by applying and drying an aqueous mixture of an aqueous polymer and a white pigment that is substantially insoluble in the electrolyte solvent.

  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.

  In the present invention, examples of the water-based polymer that does not substantially dissolve in the electrolyte solvent include a water-soluble polymer and a polymer dispersed in the water-based solvent.

Examples of water-soluble polymer compounds include proteins such as gelatin and gelatin derivatives or cellulose derivatives, natural compounds such as starch, gum arabic, dextran, pullulan, and carrageenan polysaccharides, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, and acrylamide. Examples thereof include synthetic polymer compounds such as polymers and derivatives thereof. Examples of gelatin derivatives include acetylated gelatin, phthalated gelatin, polyvinyl alcohol derivatives include terminal alkyl group-modified polyvinyl alcohol, terminal mercapto group-modified polyvinyl alcohol, and cellulose derivatives include hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, and the like. It is done. Furthermore, Research Disclosure and those described in pages (71) to (75) of JP-A No. 64-13546, US Pat. No. 4,960,681, JP-A No. 62-245260, etc. superabsorbent polymers described, namely -COOM or -SO 3 M _(M is a hydrogen atom or an alkali metal) homopolymer or a vinyl monomer together or with other vinyl monomers (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, polyvinyl alcohol, polyethylene glycol, and polyvinylpyrrolidone compounds can be preferably used.

  Polymers dispersed in an aqueous solvent include natural rubber latex, styrene butadiene rubber, butadiene rubber, nitrile rubber, chloroprene rubber, isoprene rubber and other latexes, polyisocyanate, epoxy, acrylic, silicone, polyurethane, Examples thereof include a thermosetting resin in which urea, phenol, formaldehyde, epoxy-polyamide, melamine, alkyd resin, vinyl resin and the like are dispersed in an aqueous solvent. Of these polymers, it is preferable to use an aqueous polyurethane resin described in JP-A-10-76621.

  The average molecular weight of the water-based polymer of the present invention is preferably in the range of 10,000 to 2,000,000, more preferably in the range of 30,000 to 500,000 on a weight average basis.

  Examples of the white pigment applicable in 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, Magnesium hydrogen phosphate, alkaline earth metal salt, talc, kaolin, zeolite, acidic clay, glass, organic compounds such as polyethylene, polystyrene, acrylic resin, ionomer, ethylene-vinyl acetate copolymer resin, benzoguanamine resin, urea-formalin resin, A melamine-formalin resin, a 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 is preferably used. In particular, titanium dioxide surface-treated with an inorganic oxide (Al ₂ O ₃ , AlO (OH), SiO _2, etc.), in addition to these surface treatments. Titanium dioxide that has been treated with an organic substance such as trimethylolethane, triethanolamine acetate, or trimethylcyclosilane is more preferably 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.

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

  The thickness of the porous white scattering layer is preferably in the range of 5 to 50 μm, more preferably in the range of 10 to 30 μm.

  As the alcohol solvent, a compound having high solubility in water such as methanol, ethanol, isopropanol is preferably used, and the mixing ratio with the water / alcohol solvent is preferably in the range of 0.5 to 20 by mass ratio, More preferably, it is the range of 2-10.

  In the present invention, the medium for applying the water mixture of the water-based compound and the white pigment may be at any position as long as it is on the component between the counter electrodes of the display element, but on the electrode surface of at least one of the counter electrodes. It is preferable to give to.

  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.

  As a coating method, it can select suitably from a well-known coating method. For example, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnation coater, reverse roller coater, transfer roller coater, curtain coater, double roller coater, slide hopper coater, gravure coater, kiss roll coater, bead coater, Examples include cast coaters, spray coaters, calendar coaters, and extrusion coaters.

  Drying of the water mixture of the aqueous compound and the white pigment applied on the medium may be performed 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.

  Porous as used in the present invention refers to the formation of a porous white scattering material by applying a water admixture of the water-based compound and the white pigment onto the electrode and drying it, and then the silver or silver is chemically treated on the scattering material. After supplying an electrolyte solution containing the compound contained in the structure, it can be sandwiched between opposing electrodes, giving a potential difference between the opposing electrodes, causing a silver dissolution precipitation reaction, and penetrating ions that can move between the electrodes Tell the state.

  In the display element of the present invention, it is desirable to carry out a curing reaction of the water-based compound with a curing agent during or after applying and drying the water mixture 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 aqueous compound, it is preferable to use a vinyl sulfone type hardener or a chlorotriazine type hardener alone or in combination. Moreover, when using polyvinyl alcohol, it is preferable to use boron-containing compounds such as boric acid and metaboric acid.

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

〔Electrolytes〕
The “electrolyte” as used in the present invention generally refers to a substance that dissolves in a solvent such as water and exhibits a ionic conductivity in a solution (hereinafter referred to as “narrowly defined electrolyte”). A mixture containing other metals, compounds, or the like, regardless of whether it is an electrolyte or a non-electrolyte, is called an electrolyte (“broadly defined electrolyte”).

  As the electrolyte used in the present invention, salts, acids, and alkalis that are usually used in the field of electrochemistry or the field of batteries can be used.

  There are no particular limitations on the salts, and for example, inorganic ion salts such as alkali metal salts and alkaline earth metal salts; quaternary ammonium salts; cyclic quaternary ammonium salts; quaternary phosphonium salts and the like can be used.

Specific examples of the salts include halogen ions, SCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , PF _{^{6 -, AsF 6 -, CH}} 3 COO -, CH 3 (C 6 H 4) SO 3 -, and _{(C 2 F 5 SO 2)} 3 C - Li salt having a counter anion selected from, Na salt or K salt is mentioned.

Also, halogen ions, SCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ A quaternary ammonium salt having a counter anion selected from CH ₃ COO ⁻ , CH ₃ (C ₆ H ₄ ) SO ₃ ⁻ , and (C ₂ F ₅ SO ₂ ) ₃ C ⁻ , specifically, (CH ₃ ) ₄ NBF ₄ , (C ₂ H ₅ ) ₄ NBF ₄ , (n-C ₄ H ₉ ) ₄ NBF ₄ , (C ₂ H ₅ ) ₄ NBr, (C ₂ H ₅ ) ₄ NClO ₄ , (n-C) ₄ H ₉ ) ₄ NClO ₄ , CH ₃ (C ₂ H ₅ ) ₃ NBF ₄ , (CH ₃ ) ₂ (C ₂ H ₅ ) ₂ NBF ₄ , (CH ₃ ) ₄ NSO ₃ CF ₃ , (C ₂ H _{5 ) 4 NSO 3 CF 3, (} n-C 4 H 9) ₄ NSO ₃ CF ₃ , and a compound represented by the following formula can be given.

[Ionic liquid]
An ionic liquid can be applied to the display element of the present invention. The ionic liquid referred to in the present invention is also called a room temperature molten salt, and is a salt having a melting point of 100 ° C. or lower. This salt is composed of the same number of cations and anions, and there are many substances having a melting point below room temperature depending on the molecular structure, and these are in a liquid state at room temperature without adding any solvent. An ionic liquid has a strong characteristic that it has a strong electrostatic interaction and thus has almost no vapor pressure, and does not evaporate even at high temperatures.

  The ionic liquid used in the present invention may be any substance that is generally studied and reported. In particular, an organic ionic liquid has a molecular structure that exhibits a liquid in a wide temperature range including room temperature.

The ionic liquid that can be suitably used in the present invention is represented by the formula Q ⁺ A ⁻ and is 20 to 100 ° C., preferably 20 to 80 ° C., more preferably 20 to 60 ° C., and still more preferably 20 to 40 ° C. In particular, it refers to a salt that exists as a liquid at 20 ° C., and the viscosity (25 ° C.) is not particularly limited as long as it is a melt at normal temperature, but it is preferably 1 to 200 mPa · s. Further, the cation component represented by Q + in the formula is preferably an onium cation, and more preferably an ammonium cation, an imidazolium cation, a pyridinium cation, a sulfonium cation, and a phosphonium cation.

The above ionic liquid will be specifically described in detail. As Q ⁺ in the above formula, R ₁ R ₂ R ₃ R ₄ N ⁺ , R ₁ R ₂ R ₃ S ⁺ , R ₁ R ₂ R ₃ R ₄ P ⁺ , R ₁ R ₂ N ⁺ = CR ₃ R ₄ , R ₁ R ₂ P ⁺ = CR ₃ R ₄ [where R ₁ to R ₄ are, independently of one another, hydrogen, saturated or unsaturated carbon C 1 -C 12 alkyl group, a cycloalkyl group having 3 to 8 carbon atoms, an aryl group or an aralkyl group having a carbon number of 7-11 having 6 to 10 carbon _{atoms, R 5 -X- (R 6 -Y-} ) n - (Wherein R ₅ represents an alkyl group having 4 or less carbon atoms, R ₆ represents an alkylene group having 4 or less carbon atoms, X and Y represent an oxygen atom or a sulfur atom, and n represents an integer of 0 to 10). And the group may be substituted] ammonium selected from the group consisting of Phosphonium _{^{ion, R 1 R 2 N + =}} CR 3 -R 7 -R 3 C = N + R 1 R 2, R 1 R 2 S + -R 7 -S + R 1 R 2, R 1 R 2 P + ^{_{= CR 3 -R 7 -R 3 C}} = P + R 1 R 2 ( _wherein, R 1, _{R 2} and _{R 3} are the same as defined above, and _{R 7} is 1 to carbon atoms A quaternary ammonium and / or phosphonium ion selected from the group consisting of 6 alkylene or phenylene groups, which may have a substituent, and nitrogen represented by the following general formula: Examples thereof include nitrogen ions containing 1, 2 or 3 atoms selected from sulfur and phosphorus atoms, ammonium ions derived from sulfur and phosphorus atom-containing heterocycles, sulfonium ions, phosphonium ions, and the like.

Wherein R ₁ and R ₂ are as defined above, and Z is an atom capable of constituting a 4-10 membered ring containing N ⁺ , N ⁺ = C, S ⁺ , P ⁺ or P ⁺ = C And the constituent atoms may have a substituent.

Specific examples of R ₁ to R _{4 in} the above are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, A linear or branched alkyl group such as nonyl and decyl; a cycloalkyl group such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl; unsubstituted or halogen atoms (eg, F, Cl, Br, I ), Hydroxyl group, lower alkoxy group (eg, methoxy, ethoxy, propoxy, butoxy, etc.), carboxyl group, acetyl group, propanoyl group, thiol group, lower alkylthio group (eg, methylthio, ethylthio, propylthio, butylthio, etc.) Each group), amino group, lower alkyl Amino group include phenyl having one to three substituents, such as di-lower alkyl amino group, naphthyl, tolyl, aryl group xylyl, and the like aralkyl groups such as benzyl. Further, specific examples of _{R 5} include methyl, ethyl, n- propyl, isopropyl, n- butyl, isobutyl, sec- butyl, and alkyl group such as tert- butyl group, methylene as _{R 6} And alkylene groups such as ethylene, propylene and butylene groups. Furthermore, specific examples of R ₇ include alkylene groups such as methylene, ethylene, propylene, and butylene, and phenylene groups such as phenylene.

Further, A in the formula ^- Examples of the counter anion represented by, hexafluorophosphate, hexafluoroantimonate, hexafluoroarsenate, fluorosulfonate salts, tetrafluoroborate, nitrate, alkyl sulfonate Represents a fluorinated alkyl sulfonate or a hydrogen sulfate.

  Furthermore, WO95 / 18456, JP-A-8-259543, JP-A-2001-243959, Electrochemistry 65, 11, 923 (1997), EP-716288, J. Org. Electrochem. Soc. , Vol. 143, no. 10, 3099 (1996), Inorg. Chem. The pyridinium salts, imidazolium salts, triazolium salts and the like described in 1996, 35, 1168 to 1178 can be selected and used in a timely manner according to the present invention.

[Solid electrolyte, gel electrolyte]
The electrolyte according to the present invention is not only a solution electrolyte composed of a solvent or an ionic liquid, but also a high-viscosity electrolyte or a gel electrolyte (hereinafter, referred to as a solid electrolyte or a polymer compound containing substantially no solvent). Gel electrolyte) can be used.

  Examples of the solid electrolyte and gel electrolyte applicable to the present invention include a solid electrolyte described in JP-A No. 2002-341387, a polymer solid electrolyte described in JP-A No. 2002-341387, and JP-A No. 2004-20928. A solid polymer electrolyte described in JP-A No. 2004-191945, a solid polymer electrolyte described in JP-A No. 2005-338204, and a polymer described in JP-A No. 2006-323022 Examples thereof include solid electrolytes, solid electrolytes described in JP-A No. 2007-141658, solid electrolytes described in JP-A No. 2007-163865, and gel electrolytes.

(Electronic insulation layer)
In the display element of the present invention, an electronic insulating layer can be provided.

  The electronic insulating layer applicable to the present invention may be a layer having both ionic conductivity and electronic insulating properties. For example, a solid electrolyte membrane in which a polymer or salt having a polar group is formed into a film, electronic insulating properties And a porous solid body having a low relative dielectric constant, such as a silicon-containing compound, and the like.

  As a method for forming a porous film, a sintering method (fusing method) (using fine pores formed between particles by partially fusing polymer fine particles or inorganic particles by adding a binder, etc.), extraction method ( After forming a constituent layer with a solvent-soluble organic substance or inorganic substance and a binder that does not dissolve in the solvent, the organic substance or inorganic substance is dissolved with the solvent to obtain pores), and the polymer is heated or degassed Known forming methods such as a foaming method in which foaming is performed, a phase change method in which a mixture of polymers is phase-separated by operating a good solvent and a poor solvent, and a radiation irradiation method in which pores are formed by radiating various types of radiation Can be used. Specifically, JP-A-10-30181, JP-A-2003-107626, JP-B-7-95403, JP-A-2635715, JP-A-2894523, JP-A-2987474, JP-A-3066426, and JP-A-3464513. No. 3,483,464, No. 3535942, No. 30622203, and the like.

[Thickener added with electrolyte]
In the display element of the present invention, a thickener can be used for the electrolyte. 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 (epoxide) s, 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]
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.

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

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

Additive RD17643 RD18716 RD308119
Page Classification Page Classification Page Classification Chemical sensitizer 23 III 648 Upper right 96 III
Sensitizing dye 23 IV 648-649 996-8 IV
Desensitizing dye 23 IV 998 IV
Dye 25-26 VIII 649-650 1003 VIII
Development accelerator 29 XXI 648 Upper right Anti-fogging agent / stabilizer
24 IV 649 Upper right 1006-7 VI
Brightener 24 V 998 V
Hardener 26 X 651 Left 1004-5 X
Surfactant 26-7 XI 650 Right 1005-6 XI
Antistatic agent 27 XII 650 Right 1006-7 XIII
Plasticizer 27 XII 650 Right 1006 XII
Slipper 27 XII
Matting agent 28 XVI 650 Right 1008-9 XVI
Binder 26 XXII 1003-4 IX
Support 28 XVII 1009 XVII
〔substrate〕
The substrate that can be used in the present invention is preferably a transparent substrate. Examples of such a transparent substrate include polyester (for example, polyethylene terephthalate), polyimide, polymethyl methacrylate, polystyrene, polypropylene, polyethylene, and polyamide. Nylon, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyether sulfone, silicon resin, polyacetal resin, fluororesin, cellulose derivative, polyolefin and other polymer films, plate substrates, glass substrates, and the like are preferably used. The transparent substrate used in the present invention refers to a substrate having a transmittance for visible light of at least 50%.

  Further, as the counter substrate, for example, an opaque substrate such as an inorganic substrate such as a metal substrate or a ceramic substrate can be used.

〔electrode〕
In the display element of the present invention, the following various electrodes can be used as the counter electrode.

(Display side transparent electrode)
Of the counter electrodes, the electrode positioned on the display side is preferably a transparent electrode.

  The transparent electrode is not particularly limited as long as it is transparent and conducts electricity. For example, Indium Tin Oxide (ITO: Indium Tin Oxide), Indium Zinc Oxide (IZO: Indium Zinc Oxide), Fluorine Doped Tin Oxide (FTO), Indium Oxide, Zinc Oxide, Platinum, Gold, Silver, Rhodium, Copper, Examples thereof include chromium, carbon, aluminum, silicon, amorphous silicon, and BSO (Bismuth Silicon Oxide).

  In addition, polythiophene, polypyrrole, polyaniline, polyacetylene, polyparaphenylene, polyselenophenylene, etc., and their modifying compounds can be used alone or in combination.

  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.

(Transparent porous electrode)
As one embodiment of the transparent electrode, a nanoporous electrode having a nanoporous structure can be provided on the transparent electrode. This nanoporous electrode is substantially transparent when a display element is formed, and can carry an electroactive substance such as an electrochromic dye.

  The nanoporous structure as used in the present invention refers to a state in which an infinite number of nanometer-sized pores exist in a layer and ionic species contained in the electrolyte can move within the nanoporous structure.

  As a method for forming such a nanoporous electrode, a dispersion containing fine particles constituting the nanoporous electrode is formed in layers by an ink jet method, a screen printing method, a blade coating method, etc., and then heated at a predetermined temperature. A method of making porous by drying, baking, a method of making nanoporous by anodizing or photoelectrochemical etching after forming an electrode layer by sputtering, CVD, atmospheric pressure plasma, etc. Is mentioned. Also, the sol-gel method, Adv. Mater. It can also be formed by the method described in 2006, 18, 2980-2983.

The main components of the fine particles constituting the nanoporous electrode are metals such as Cu, Al, Pt, Ag, Pd and Au, metal oxides such as ITO, SnO ₂ , TiO ₂ and ZnO, carbon nanotubes, glassy carbon, and diamond. It can be selected from carbon electrodes such as like carbon and nitrogen-containing carbon, and is preferably selected from metal oxides such as ITO, SnO ₂ , TiO ₂ , and ZnO.

  In order for the nanoporous electrode to have transparency, it is preferable to use fine particles having an average particle diameter of about 5 nm to 10 μm. As the shape of the fine particles, those having an arbitrary shape such as an indefinite shape, a needle shape, and a spherical shape can be used.

  The film thickness of the nanoporous electrode is preferably in the range of 0.1 to 10 μm, more preferably in the range of 0.25 to 5 μm.

(Grid electrode: auxiliary electrode)
An auxiliary electrode can be attached to at least one of the counter electrodes according to the present invention.

  The auxiliary electrode is preferably made of a material having a lower electrical resistance than the main electrode portion. For example, metals such as platinum, gold, silver, copper, aluminum, zinc, nickel, titanium, and bismuth and alloys thereof can be preferably used.

  The auxiliary electrode can be installed either between the main electrode portion and the substrate, or on the surface of the main electrode portion opposite to the substrate. In any case, it is only necessary that the auxiliary electrode is electrically connected to the main electrode portion.

  There are no particular restrictions on the arrangement pattern of the auxiliary electrodes. It can be appropriately formed according to the required performance, such as linear, mesh, or circular. When the main electrode part is divided into a plurality of parts, the divided electrode parts may be connected to each other. However, in the case where the main electrode portion is a transparent electrode provided on the substrate on the display side, the auxiliary electrode is required to be provided with a shape and frequency that do not impair the visibility of the display element.

  As a method of forming the auxiliary electrode, a known method can be used. For example, patterning may be performed by photolithography, printing, ink-jet printing, electrolytic plating, electroless plating, or exposure and development using a silver salt photosensitive material to form a pattern.

  The line width and line spacing of the auxiliary electrode pattern may be arbitrary values, but the line width needs to be increased in order to increase the conductivity. On the other hand, when an auxiliary electrode is attached to the transparent electrode, from the viewpoint of visibility, the area coverage of the auxiliary electrode viewed from the display element observation side is preferably 30% or less, and more preferably 10% or less.

  Thus, from the viewpoint of transmittance and conductivity, the line width of the auxiliary electrode is preferably 1 μm or more and 100 μm or less, and the line interval is preferably 50 μm to 1000 μm.

(Method of forming electrode)
A known method can be used to form the transparent electrode and the metal auxiliary electrode. For example, a method of depositing a mask on a substrate by a sputtering method or the like, a method of patterning by a photolithography method after forming the entire surface, and the like can be given.

  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 a coating method, for example, a known method such as a dipping method, a spinner method, a spray method, a roll coater method, a flexographic printing method, a screen printing method, or the like can be used.

  Among the ink jet methods, the following electrostatic ink jet method is capable of continuously printing a highly viscous liquid 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 method>
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. It is one of the preferable embodiments that the liquid discharge device is provided with a supply unit that performs the discharge and a discharge voltage application unit that applies a discharge voltage to the solution in the nozzle. Further, it is preferable that the solution in the nozzle is formed by using a discharge device provided with a convex meniscus forming means for forming a state where the solution rises from the nozzle tip.

  In addition, it comprises operation control means for controlling application of drive voltage for driving the convex meniscus forming means and application of discharge voltage by the discharge voltage application means, and this operation control means applies application of the discharge voltage by the discharge voltage application means. 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.

  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 an operation for raising the solution by the convex meniscus forming unit, and application of the discharge voltage. A liquid discharge device having a second discharge control unit that synchronizes the liquid, and the operation control means includes a liquid level at the tip of the nozzle after the swell operation of the solution and the application of the discharge voltage. It is also a preferred form to use a liquid ejection apparatus having a liquid level stabilization control unit that performs operation control for drawing in the inside.

  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.

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

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

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

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

[Display element driving method]
The driving operation of the display element of the present invention may be simple matrix driving or active matrix driving. The simple matrix driving in the present invention is a driving method in which a current is sequentially applied to a circuit in which a positive line including a plurality of positive electrodes and a negative electrode line including a plurality of negative electrodes are opposed to each other in a vertical direction. Say that. By using simple matrix driving, there is an advantage that the circuit configuration and driving IC can be simplified and manufactured at low cost. The active matrix drive is a system in which scanning lines, data lines, and current supply lines are formed in a grid pattern, and are driven by TFT circuits provided in each grid pattern. Since switching can be performed for each pixel, there are merits such as gradation and memory function. For example, a circuit described in FIG. 5 of JP-A-2004-29327 can be used.

[Product application]
The display element of the present invention can be used in an electronic book field, an ID card field, a public field, a traffic field, a broadcast field, a payment field, a distribution logistics field, and the like. Specifically, keys for doors, student ID cards, employee ID cards, various membership cards, convenience store cards, department store cards, vending machine cards, gas station cards, subway and railway cards, bus cards, Cash cards, credit cards, highway cards, driver's licenses, hospital examination cards, electronic medical records, health insurance cards, Basic Resident Registers, passports, electronic books, etc.

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

Example 1
<< Production of display element >>
(Preparation of electrolyte)
(Preparation of electrolyte 1-1)
In 2.5 g of the compound (S1-4), 0.1 g of silver p-toluenesulfonate, 0.2 g of the compound (G2-12) and 0.025 g of bis (trifluoromethylsulfonyl) imide lithium are dissolved. Thus, an electrolytic solution 1-1 was obtained.

[Production of electrodes]
(Preparation of electrode 1-1)
An ITO (Indium Tin Oxide, Indium Tin Oxide) film was formed on a glass substrate having a thickness of 1.5 mm and 2 cm × 4 cm according to a known method to obtain a transparent electrode (electrode 1-1).

(Preparation of electrode 1-2)
A gold thin film was formed on a 2 cm × 4 cm glass / chromium electrode having a thickness of 1.5 mm according to a known method to obtain an electrode 1-2.

(Preparation of electrode 1-3)
A silver thin film was formed on electrode 1-1 so as to have a silver purity of 99.5% and a film thickness of 20 nm by sputtering to produce electrode 1-3.

(Preparation of electrode 1-4)
A silver thin film was formed on the electrode 1-1 so as to have a silver purity of 99.5% and a film thickness of 5 nm by sputtering to produce an electrode 1-4.

(Preparation of electrode 1-5)
A silver thin film was formed on the electrode 1-1 so as to have a silver purity of 99.5% and a film thickness of 3 nm by sputtering to produce an electrode 1-5.

(Preparation of electrode 1-6)
A silver thin film was formed on the electrode 1-1 so as to have a silver purity of 99.5% and a film thickness of 50 nm by a sputtering method to prepare an electrode 1-6.

(Preparation of electrode 1-7)
A silver thin film was formed on the electrode 1-1 so as to have a silver purity of 99.5% and a film thickness of 60 nm by sputtering to produce an electrode 1-7.

(Preparation of electrode 1-8)
A silver thin film was formed on the electrode 1-1 so as to have a silver purity of 99.0% and a film thickness of 20 nm by sputtering to produce an electrode 1-8.

(Preparation of electrode 1-9)
A silver thin film was formed on the electrode 1-1 so as to have a silver purity of 98.0% and a film thickness of 20 nm by sputtering to produce an electrode 1-9.

(Preparation of titanium dioxide dispersion)
Kuraray Poval PVA235 (manufactured by Kuraray Co., Ltd., polyvinyl alcohol resin) was added to the water / ethanol mixed solution so as to have a solid content concentration of 2% by mass, dissolved by heating, and then titanium dioxide CR-90 made by Ishihara Sangyo Co., Ltd. Was dispersed with an ultrasonic disperser so as to be 20% by mass to obtain a titanium dioxide dispersion.

[Production of display element]
(Preparation of display element 1-1)
On the electrode 1-2, the above-mentioned titanium dioxide dispersion was screen-printed so that the average film thickness after drying was 20 μm, then dried at 50 ° C. for 30 minutes to evaporate the solvent, and then in an atmosphere at 85 ° C. The electrode 1-2a which dried for 1 hour and formed the porous white scattering layer was produced. After the 2 cm × 2 cm portion in the vicinity of the center of the electrode 1-2a is trimmed with an olefin-based sealant containing 10% glass spherical beads having an average particle diameter of 40 μm as a volume fraction, the electrode 1-2a and the electrode 1- 1 were bonded so as to be orthogonal to 1 and further heated and pressed to prepare an empty cell having a notch portion of the inlet. The electrolytic solution 1-1 was vacuum-injected into the empty cell, and the injection port was sealed with an epoxy-based ultraviolet curable resin to produce a display element 1-1.

(Preparation of display element 1-2)
A display element 1-2 was produced in the same manner as the display element 1-1 except that the electrode 1-2 was changed to the electrode 1-1.

(Preparation of display element 1-3)
A voltage is applied for 5 seconds between the counter electrodes so that the observation side electrode (the electrode on which the porous white scattering layer is not formed) of the display element 1-1 is +1.2 V, and the non-observation side electrode Precipitated silver was formed on (the electrode on which the porous white scattering layer was formed) to produce a display element 1-3.

(Preparation of display element 1-4)
A display element 1-4 was produced in the same manner as the display element 1-1 except that the electrode 1-2 was changed to the electrode 1-3.

(Preparation of display element 1-5)
Display element 1-5 was produced in the same manner as display element 1-1 except that electrode 1-1 was changed to electrode 1-3 and electrode 1-2 was changed to electrode 1-1.

(Preparation of display element 1-6)
The voltage between the counter electrodes is set so that the observation side electrode (the electrode on which the porous white scattering layer is not formed) of the display element 1-5 becomes +1.2 V, and the observation-side silver thin film is visually observed. The application was continued until completely dissolved. At this time, it was confirmed that precipitated silver was formed on the non-observation side electrode (the electrode on which the porous white scattering layer was formed), and the obtained display element was designated 1-6.

(Preparation of display elements 1-7 to 1-15)
Display elements 1-7 to 1-15 are the same as display element 1-6 except that the voltage at the time of melting the observation side electrode, the non-observation side electrode, and the silver thin film is changed to the combination shown in Table 1. Produced.

<< Evaluation of display element >>
[Evaluation of reflectance stability when driven repeatedly]
When both electrodes of the display element are connected to both terminals of the constant voltage power source, a voltage of +1.5 V is applied for 1 second, and then a voltage of -1.5 V is applied for 0.5 second to display gray The reflectance at a wavelength of 550 nm was measured with a spectrocolorimeter CM-3700d manufactured by Konica Minolta Sensing. Under the same driving conditions, driving was performed 10 times in total, and the average value of the obtained reflectances was defined as R _ave1 . Further, after driving repeatedly 10,000 times, R _ave2 was obtained by the same method. ΔR _BK1 = | R _ave1 −R _ave2 | was used as an index of stability of reflectance when ΔR _BK1 was repeatedly driven. Here, the smaller the value of ΔR _BK1, the better the stability of the reflectance when driven repeatedly.

  As is apparent from the results shown in Table 1, it can be seen that the display element satisfying the configuration of the present invention has improved reflectance stability when it is repeatedly driven as compared with the comparative example.

Example 2
<< Production of display element >>
(Preparation of electrolyte)
(Preparation of electrolyte 2-1)
In 2.5 g of the compound (S1-4), 0.1 g of silver p-toluenesulfonate, 0.2 g of the compound (G2-12) and 0.025 g of bis (trifluoromethylsulfonyl) imide lithium are dissolved. Thus, an electrolytic solution 2-1 was obtained.

[Production of electrodes]
(Preparation of electrode 2-1)
An ITO (Indium Tin Oxide) film was formed on a 2 cm × 4 cm glass substrate having a thickness of 1.5 mm according to a known method to obtain a transparent electrode (electrode 2-1).

(Preparation of electrode 2-2)
A gold thin film was formed on a 2 cm × 4 cm glass / chromium electrode having a thickness of 1.5 mm according to a known method to obtain an electrode 2-2.

(Preparation of electrode 2-3)
A silver thin film was formed on the electrode 2-1 by sputtering so as to have a silver purity of 99.5% and a film thickness of 20 nm to prepare an electrode 2-3.

(Preparation of electrode 2-4)
A silver thin film was formed on the electrode 2-1 by sputtering to form a silver thin film having a silver purity of 99.5% and a film thickness of 5 nm to produce an electrode 2-4.

(Preparation of electrode 2-5)
A silver thin film was formed on the electrode 2-1 by sputtering so that the silver purity was 99.5% and the film thickness was 3 nm, and an electrode 2-5 was produced.

(Preparation of electrode 2-6)
A silver thin film was formed on the electrode 2-1 by sputtering so that the silver purity was 99.5% and the film thickness was 50 nm, and an electrode 2-6 was produced.

(Preparation of electrode 2-7)
A silver thin film was formed on the electrode 2-1 by sputtering so that the silver purity was 99.5% and the film thickness was 60 nm, whereby an electrode 2-7 was produced.

(Preparation of electrode 2-8)
A silver thin film was formed on the electrode 2-1 by sputtering so that the silver purity was 99.0% and the film thickness was 20 nm, and an electrode 2-8 was produced.

(Preparation of electrode 2-9)
A silver thin film was formed on the electrode 2-1 by sputtering so that the silver purity was 98.0% and the film thickness was 20 nm, and an electrode 2-9 was produced.

(Preparation of titanium dioxide dispersion)
Kuraray Poval PVA235 (manufactured by Kuraray Co., Ltd., polyvinyl alcohol resin) was added to the water / ethanol mixed solution so as to have a solid content concentration of 2% by mass, dissolved by heating, and then titanium dioxide CR-90 made by Ishihara Sangyo Co., Ltd. Was dispersed with an ultrasonic disperser so as to be 20% by mass to obtain a titanium dioxide dispersion.

[Production of display element]
(Preparation of display element 2-1)
On the electrode 2-2, the above titanium dioxide dispersion was screen-printed so that the average film thickness after drying was 20 μm, then dried at 50 ° C. for 30 minutes to evaporate the solvent, and then in an atmosphere at 85 ° C. The electrode 2-2a was dried for 1 hour to form a porous white scattering layer. After rimming the periphery of the electrode 2-2a with an olefin-based sealant containing glass spherical beads having an average particle diameter of 40 μm as a volume fraction of 10%, the electrode 2-2a and the electrode 2-1 are orthogonal to each other. And then heated and pressed to produce an empty cell. The electrolytic solution 2-1 was vacuum-injected into the empty cell, and the injection port was sealed with an epoxy-based ultraviolet curable resin to produce a display element 2-1.

(Preparation of display element 2-2)
A display element 2-2 was produced in the same manner as the display element 2-1, except that the electrode 2-2 was changed to the electrode 2-1.

(Preparation of display element 2-3)
A voltage is applied for 5 seconds between the counter electrodes so that the observation side electrode of the display element 2-1 (the electrode on which the porous white scattering layer is not formed) is +1.2 V, and the non-observation side electrode Precipitated silver was formed on (the electrode on which the porous white scattering layer was formed) to produce a display element 2-3.

(Preparation of display element 2-4)
A display element 2-4 was produced in the same manner as the display element 2-1, except that the electrode 2-2 was changed to the electrode 2-3.

(Preparation of display element 2-5)
A display element 2-5 was produced in the same manner as the display element 2-1, except that the electrode 2-1 was changed to the electrode 2-3 and the electrode 2-2 was changed to the electrode 2-1.

(Preparation of display element 2-6)
The non-observation side silver thin film is set by setting the voltage between the counter electrodes so that the observation side electrode (the electrode on which the porous white scattering layer is not formed) of the display element 2-4 is -1.2V. The application was continued until it was completely dissolved visually. At this time, it was confirmed that precipitated silver was formed on the observation-side electrode (the electrode on which the porous white scattering layer was formed). Next, the voltage between the counter electrodes was set so that the observation side electrode was +1.2 V, and the application was continued until the observation-side precipitated silver was completely dissolved visually. At this time, it was confirmed that deposited silver was formed on the non-observation side electrode, and the obtained display element was designated 2-6.

(Preparation of display elements 2-7 to 2-15)
The display elements 2-7 to 2-15 are the same as the display element 2-6 except that the voltage at the time of melting the observation side electrode, the non-observation side electrode, and the silver thin film is changed to the combination shown in Table 2. Produced.

<< Evaluation of display element >>
[Evaluation of reflectance stability when driven repeatedly]
When both electrodes of the display element are connected to both terminals of the constant voltage power source, a voltage of +1.5 V is applied for 1 second, and then a voltage of -1.5 V is applied for 0.5 second to display gray The reflectance at a wavelength of 550 nm was measured with a spectrocolorimeter CM-3700d manufactured by Konica Minolta Sensing. Under the same driving conditions, driving was performed 10 times in total, and the average value of the obtained reflectances was defined as R _ave1 . Further, after driving repeatedly 10,000 times, R _ave2 was obtained by the same method. ΔR _BK1 = | R _ave1 −R _ave2 | was used as an index of stability of reflectance when ΔR _BK1 was repeatedly driven. Here, the smaller the value of ΔR _BK1, the better the stability of the reflectance when driven repeatedly.

  As is apparent from the results shown in Table 2, it can be seen that the display element satisfying the configuration of the present invention has improved reflectance stability when it is repeatedly driven as compared with the comparative example.

DESCRIPTION OF SYMBOLS 1 Observation side glass substrate 2 Observation side electrode 3 Non-observation side glass substrate 4 Non-observation side electrode 5 Silver thin film 6 Electrolyte solution 7,8 Deposited silver

Claims (7)

  In an electrochemical display element having an electrolytic solution containing at least a silver salt compound between a pair of counter electrodes configured on the observation side and the non-observation side, a silver thin film is formed in advance on at least one of the pair of counter electrodes An electrochemical display element comprising: a step of forming precipitated silver on an electrode opposite to an electrode on which the silver thin film is formed while applying an electric field between the counter electrodes to dissolve the silver thin film Production method.   A method for producing the electrochemical display device according to claim 1, wherein a step of forming a silver thin film in advance on the observation side electrode, a step of making the observation side electrode and the non-observation side electrode face each other, and the opposite electrode A step of filling the electrolyte solution in between, reducing the silver compound in the electrolyte solution while applying a voltage between the electrodes so that the observation side electrode becomes noble and dissolving the silver thin film on the observation side The method for producing an electrochemical display element according to claim 1, further comprising a step of forming precipitated silver on the electrode.   A method for producing an electrochemical display device according to claim 1, wherein a step of forming a silver thin film in advance on the non-observation side electrode, a step of facing the non-observation side electrode and the observation side electrode, and an opposing electrode A step of filling the electrolyte solution in between, a silver compound in the electrolyte solution on the observation side electrode while applying a voltage between the counter electrodes so that the observation side electrode becomes base and dissolving the silver thin film on the non-observation side Reducing the silver compound in the electrolyte while applying a voltage between the pair of electrodes so that the observation side electrode becomes noble and dissolving the precipitation silver on the observation side The method for producing an electrochemical display element according to claim 1, further comprising a step of forming precipitated silver on the non-observation side electrode.   The method for producing an electrochemical display element according to any one of claims 1 to 3, wherein a purity of silver in the silver thin film is 99% or more and 100% or less.   The method for manufacturing an electrochemical display element according to any one of claims 1 to 4, wherein the silver thin film is formed by a sputtering method.   6. The method for producing an electrochemical display element according to claim 1, wherein the silver thin film has a thickness of 5 nm to 50 nm.   The method for producing an electrochemical display element according to claim 1, wherein a voltage applied between the counter electrodes is 0.5 V or more and 1.2 V or less.

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