JP2008224717A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device which suppresses the occurrence of display unevenness by preventing electrophoresis of developed silver without reducing a display speed. <P>SOLUTION: The display device has an electrolyte containing at least silver or a compound including silver in its chemical structure, between electrodes facing each other and has the electrodes driven so as to cause precipitation and dissolution of silver and contains a compound having a group which interacts with silver precipitated between the electrodes. <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.

  As a display method for solving the disadvantages of each of the above-mentioned methods, there are an electrochromic display element (hereinafter abbreviated as EC method) and an electrodeposition method (hereinafter abbreviated as ED method) using dissolution precipitation of metal or metal salt. Are known. The EC method has the advantage of being capable of full-color display at a low voltage of 3V or less, a simple cell configuration, and excellent white quality. The ED method can also be driven at a low voltage of 3V or less and is a simple cell. There are advantages such as excellent configuration, black-to-white contrast and black quality, and various methods have been disclosed (see, for example, Patent Documents 1 to 5).

  However, when the viscosity of the electrolyte solution included in the display device of the above method is low, for example, in the ED method, silver black migrates during black display, and display unevenness and a decrease in contrast are likely to occur. In addition to this, the blackened silver tends to disappear during whitening. In order to prevent this, there is a method of increasing the viscosity of the electrolytic solution.

Patent Document 6 discloses a gel composition, a gel ion conductive composition based on the gel composition, and a compound having three or more organosilicon compounds and ethylenic double bonds in a battery and an electrochemical device using the gel composition. There is a description that the electrolyte layer contains a gel-like ion conductive composition comprising a compound obtained by addition polymerization of a polymer, a solvent, and an ion conductive material. Patent Document 7 discloses a display element containing a colored substance and a polymer electrolyte in which the electrolytic solution changes color by electrochemical reduction or oxidation, and the polymer electrolyte is a starting material made of an uncrosslinked polymer or monomer. Is formed by cross-linking polymerization. All of these methods are gel electrolytes, and increase the viscosity of the electrolyte to stabilize the characteristics. However, although only a method of increasing the viscosity can prevent the migration of silver black to a certain extent, the present situation is that it has a big problem that the display speed is lowered accordingly.
WO2004 / 068231 Specification WO 2004/066773 specification U.S. Pat. No. 4,240,716 Japanese Patent No. 3428603 JP 2003-241227 A W02001 / 090249 specification JP 2003-5224 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a display element that prevents migration of silver black and suppresses display unevenness without reducing display speed. is there.

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

  1. A display element having an electrolyte containing at least 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, the counter electrode A display element comprising a compound having a group that interacts with silver deposited therebetween.

  2. 2. The display element according to 1 above, wherein the compound having a group that interacts with the precipitated silver is a compound represented by the following general formula (1).

[Wherein, X _{1 to} X ₄ each represent —NR ₁ , —S— or —O—. R ₁ represents a bond for forming a double bond with a hydrogen atom or an adjacent atom. Y _{1 to} Y ₄ each represent CR ₂ or a nitrogen atom. R ₂ represents a bond for forming a double bond with a hydrogen atom or an adjacent atom. Z _{1 to} Z ₄ each represents an atomic group for forming a heterocyclic ring together with X _{1 to} X ₄ and Y _{1 to} Y ₄ . Heterocycle formed by Z ₁ , X ₁ and Y ₁ , Heterocycle formed by Z ₂ , X ₂ and Y ₂ , Heterocycle formed by Z ₃ , X ₃ and Y ₃ and Z ₄ , X ₄ And the heterocycle formed by Y ₄ may have a substituent, and may form a condensed ring. L represents a linking group or a simple bond between the heterocyclic ring formed of Z ₂ , X ₂ and Y ₂ and the heterocyclic ring formed of Z ₄ , X ₄ and Y ₄ . ]
3. 3. The display device according to 2 above, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2).

[Wherein, R _{3 to} R ₆ each represent a substituent. Moreover, R < ₃ > -R < ₆ > may have another substituent, respectively. L represents a linking group or a simple bond between two bipyridine groups. ]
4). 2. The display element according to 1 above, wherein the compound having a group that interacts with the precipitated silver is a compound represented by the following general formula (3).

[In the formula, A is

(Wherein x represents an integer of 1 to 20, and y represents an integer of 1 to 60)
B represents an oxygen atom, a methylene group, an alkylene group, an alkyleneoxy group, a phenyleneoxy group or a simple bond. ]
5. 5. The display element according to any one of 1 to 4, wherein the electrolyte has a viscosity at 25 ° C. of 0.01 Pa · s or more and 5.0 Pa · s or less.

  6). 6. The display element according to any one of 1 to 5 above, wherein the compound having a group that interacts with the precipitated silver has a weight average molecular weight of 2,000 or more and 10,000 or less.

  7). 7. The display element according to any one of 1 to 6, wherein the compound having a group that interacts with the precipitated silver is adsorbed on titanium oxide.

  8). 8. The display element according to any one of 1 to 7, wherein the electrolyte contains a compound represented by the following general formula (4) or general formula (5).

General formula (4)
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. ]
9. 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 8 above, wherein a condition defined by the following formula (1) is satisfied when the mole / kg) is satisfied.

Formula (1)
0 ≦ [X] / [Ag] ≦ 0.01

  According to the present invention, it has been possible to provide a display element that prevents the migration of silver black and suppresses the occurrence of display unevenness without reducing the display speed.

  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 at least silver or a compound containing silver in a chemical structure between opposing electrodes, and causes dissolution and precipitation of silver. A display element that performs a driving operation of the counter electrode, wherein the display element includes a compound having a group that interacts with silver deposited between the counter electrodes, without reducing the display speed, As soon as the present invention has been found, it has been found that a display element can be realized in which the occurrence of display unevenness is prevented by preventing migration of silver black.

  That is, the display element having an electrolyte having the above-described configuration defined in the present invention can prevent the migration of silver black in the counter electrode without excessively increasing the viscosity of the electrolyte and without reducing the display speed. The occurrence of unevenness could be suppressed.

  In particular, by using the compound represented by the general formula (1), the general formula (2), or the general formula (3) according to the present invention as a compound having a group that interacts with precipitated silver according to the present invention. Further, migration of blackened silver (precipitated silver) can be prevented, and as a result, occurrence of display unevenness can be suppressed.

Therefore, from the viewpoint of preventing migration of blackened silver (precipitated silver) by constituting an electrolyte containing a compound having a group that interacts with precipitated silver according to the present invention, it is excessive as in the prior art. In the present invention, it is not necessary to have a high viscosity.
The viscosity of the electrolyte solution of the display elements of claims (1) to (4) can be in the range of 0.01 Pa · s to 5.0 Pa · s. If the viscosity of the electrolyte is 0.01 Pa · s or more, an electrolyte having a desired viscosity can be easily adjusted, and if it is 5.0 Pa · s or less, the display speed does not decrease. , Display unevenness can be effectively prevented.

  The compound having a group that interacts with precipitated silver according to the present invention preferably has a weight average molecular weight of 2,000 or more and 10,000 or less. If the weight average molecular weight is 2000 or more, sufficient interaction with the precipitated silver can be exhibited, and if it is 10000 or less, the viscosity can be prevented from becoming excessively high. Can be obtained.

  The compound having a group that interacts with precipitated silver according to the present invention may be included in the electrolyte between the counter electrodes, or may be included in the white scattering layer between the counter electrodes. When it is contained in the electrolyte or white scattering layer between the counter electrodes, the electrolyte or white scattering layer preferably contains at least titanium oxide, and the compound having a group that interacts with silver is adsorbed on titanium oxide.

  Details of the present invention will be described below.

〔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”).

  In addition to the compounds represented by the general formulas (1) to (3) according to the present invention, the electrolyte formed between the counter electrodes according to the present invention includes an organic solvent, an ionic liquid, a redox active substance, a supporting electrolyte, A complexing agent, a polymer binder, and the like are selected as necessary.

  Hereinafter, each component of the electrolyte according to the present invention will be further described.

[Compound represented by the general formula (1)]
In the display element of the present invention, the compound having a group that interacts with silver deposited between the counter electrodes is preferably a compound represented by the general formula (1).

In the general formula (1), X _{1 to} X ₄ each represent —NR ₁ , —S— or —O—. R ₁ represents a bond for forming a double bond with a hydrogen atom or an adjacent atom. Y _{1 to} Y ₄ each represent CR ₂ or a nitrogen atom. R ₂ represents a bond for forming a double bond with a hydrogen atom or an adjacent atom. Z _{1 to} Z ₄ each represents an atomic group for forming a heterocyclic ring together with X _{1 to} X ₄ and Y _{1 to} Y ₄ . A heterocycle formed by Z ₁ , X ₁ and Y ₁ , a heterocycle formed by Z ₂ , X ₂ and Y ₂ , a heterocycle formed by Z ₃ , X ₃ and Y ₁ , and Z ₄ , X ₄ And the heterocycle formed by Y ₄ may have a substituent, and may form a condensed ring. L represents a linking group or a simple bond between the heterocyclic ring formed by Z ₂ , X ₂ and Y ₂ and the heterocyclic ring formed by Z ₄ , X ₄ and Y _4. , Methylene group, alkylene group, phenylene group and the like.

  Among the nitrogen-containing heterocycles, preferred are pyridine ring, pyrazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, pyrrole ring, imidazole ring, pyrazole ring, triazole ring, indole ring, tetrazole ring, thiazole ring, An oxazole ring, a purine ring, etc. are mentioned.

  Hereinafter, typical specific examples of the heterocyclic group constituting the compound represented by the general formula (1) according to the present invention will be given.

  Next, typical specific examples of the compound represented by the general formula (1) are listed below.

  Among the compounds represented by the general formula (1) according to the present invention, particularly preferred compounds are (A-5), (A-20), and (A-23).

[Compound represented by formula (2)]
In the present invention, the compound represented by the general formula (1) is preferably a compound represented by the general formula (2).

In the general formula (2), R _{3 to} R ₆ each represent a substituent, and examples of the substituent include a hydrogen atom, a halogen atom, a heterocyclic ring, an alkyl group, a cycloalkyl group, an aryl group, an alkenyl group, and a hydroxyl group. Group, alkoxy group, aryloxy group, carboxyl group, carbonyl group, amino group, and thiol group, and a hydrogen atom, a halogen atom, a heterocyclic ring, an alkyl group, an aryl group, an alkenyl group, and an alkoxy group are preferable. R _{3 to} R ₆ may each have other substituents. L represents a linking group or a simple bond between two bipyridine groups. Examples of the linking group include a methylene group, an alkylene group, and a phenylene group.

  Next, typical specific examples of the compound represented by the general formula (2) are listed below.

  Among the compounds represented by the general formula (2) according to the present invention, particularly preferred compounds are (B-7), (B-9), (B-11), (B-47), (B-49). ), (B-51).

[Compound represented by formula (3)]
In the display element of the present invention, the compound having a group that interacts with silver deposited between the counter electrodes is preferably a compound represented by the general formula (3).

  In the said General formula (3), A represents the said substituent, x represents the integer of 1-20, y represents the integer of 1-60, Preferably x is an integer of 2-10, y Is an integer from 3 to 40. B represents an oxygen atom, a methylene group, an alkylene group, an alkyleneoxy group, a phenyleneoxy group or a simple bond.

  Examples of the alkylene group include ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, undecamethylene, dodecamethylene, and the like. Chain alkylene group, 1-methylethylene group, 1-methyl-trimethylene group, 2-methyl-trimethylene group, 1-methyl-tetramethylene group, 2-methyl-tetramethylene group, 1-methyl-pentamethylene group, 2 An alkylene group having a branched alkyl group such as -methyl-pentamethylene group, 3-methyl-pentamethylene group, or neopentyl group can be exemplified. The alkyleneoxy group includes methyleneoxy, ethyleneoxy, trimethyleneoxy, tetramethyleneoxy, pentamethyleneoxy, hexamethyleneoxy, heptamethyleneoxy, octamethyleneoxy, nonamethyleneoxy, Methyleneoxy group, undecamethyleneoxy group, dodecamethyleneoxy group, 1-methylethyleneoxy group, 1-methyl-trimethyleneoxy group, 2-methyl-trimethyleneoxy group, 1-methyl-tetramethyleneoxy group, 2 -Methyl-tetramethyleneoxy group, 1-methyl-pentamethyleneoxy group, 2-methyl-pentamethyleneoxy group, 3-methyl-pentamethyleneoxy group, neopentyloxy group and the like can be mentioned.

  Next, typical specific examples of the compound represented by the general formula (3) are listed below.

  Among the compounds represented by the general formula (3) according to the present invention, particularly preferred compounds are (C-1) to (C-14).

[Method of adding a compound having a group interacting with silver to an electrolyte]
The compound having a group that interacts with silver represented by the compounds represented by the general formulas (1) to (3) according to the present invention dissolves each constituent material forming an electrolyte using an appropriate organic solvent. Then, it may be added and dissolved last, or the compound according to the present invention may be dissolved in advance in a solvent that can be dissolved and mixed with each constituent material that forms the electrolyte. When a white scattering layer containing titanium oxide is provided between the counter electrodes, a white scattering layer containing titanium oxide or the like is formed, and then immersed in a solution of the above compound according to the present invention so that the compound is titanium oxide. May be adsorbed and dried to be present in the white scattering layer.

[Organic solvent]
The organic solvent that can be used for the preparation of the electrolyte according to the present invention is not particularly limited as long as the organic solvent has a boiling point in the range of 120 to 300 ° C. that can remain in the electrolyte without causing volatilization after the electrolyte is formed. For example, propylene carbonate, ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, butylene carbonate, γ-butyl lactone, tetramethyl urea, sulfolane, dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone, 2- (N-methyl) -2-pyrrolidinone, hexamethylphosphortriamide, N-methylpropionamide, N, N-dimethylacetamide, N-methylacetamide, N, N dimethylformamide, N-methylformamide, butyronitrile, Lopionitrile, acetonitrile, acetylacetone, 4-methyl-2-pentanone, 2-butanol, 1-butanol, 2-propanol, 1-propanol, acetic anhydride, ethyl acetate, ethyl propionate, dimethoxyethane, diethoxyfuran, tetrahydrofuran, ethylene Examples include glycol, diethylene glycol, triethylene glycol monobutyl ether, tricresyl phosphate, 2-ethylhexyl phosphate, dioctyl phthalate, and dioctyl sebacate.

  Among the organic solvents, it is preferable to use cyclic carboxylic acid ester compounds such as propylene carbonate, ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, butylene carbonate, and γ-butyl lactone.

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

[Ionic liquid]
The electrolyte according to the present invention preferably contains an ionic liquid. The ionic liquid referred to in the present invention refers to a salt that exists even at room temperature, and can be selected from a combination of a cation such as imidazolium or pyridinium and an anion such as fluoride ion or triflate.

  In the present invention, the ionic liquid used for the electrolyte is preferably a compound represented by the following general formula (A).

  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 the 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 spiro ammonium compound salt is lowered. It 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.

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

  First, dibromoalkane brominated at both ends is allowed to act on 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, the resulting spiroammonium hydroxide solution was added with an equimolar amount of the acid component corresponding to A in the general formula [1], neutralized, and then dehydrated 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 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 (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, polyalkylene glycols, polyvinyl butyrals from the viewpoint of compatibility with various additives and improvement in dispersion stability of white particles. It is.

(White scattering layer)
In the display element of the present invention, a white scattering material that does not substantially dissolve in the electrolyte solvent can be mixed in the electrolyte, or a porous white scattering layer containing a white scattering material can be formed between the electrodes.

  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 from the viewpoint of preventing coloring at high temperatures 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.

In the electrolyte according to the present invention, the water-soluble polymer that does not substantially dissolve in the solvent includes proteins such as gelatin and gelatin derivatives, or cellulose derivatives, natural substances such as starch, gum arabic, dextran, pullulan, carrageenan and other polysaccharides. And synthetic polymer compounds such as compounds, polyvinyl alcohol, polyvinyl pyrrolidone, acrylamide 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, 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.

  In the display element of the present invention, the water mixture of the water-soluble polymer and the white pigment 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.

  In the display element of the present invention, the medium on which the water mixture of the water-soluble polymer and the white pigment is applied 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 one electrode 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.

  In the present invention, the water mixture of the water-soluble polymer and the white pigment applied on the medium may be dried by any method as long as it is a method capable of evaporating water. 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.

  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.

  Porous as used in the present invention means that after forming a porous white scatterer, an electrolyte solution containing silver or a compound containing silver in the chemical structure is provided on the scatterer, and then sandwiched between counter electrodes. This refers to a penetrating state in which a potential difference can be applied between opposing electrodes to cause a dissolution and precipitation reaction of silver, and ion species can move between the electrodes.

  When a compound having a group that interacts with silver deposited between the opposing electrodes is included in a white scattering layer between the opposing electrodes, the compound having a group that interacts with silver is adsorbed on titanium oxide. It is preferable.

[Basic structure of display element]
In the display element of the present invention, the display portion is provided with one corresponding counter electrode. A transparent electrode such as an ITO electrode is provided on the electrode 1 which is one of the counter electrodes close to the display portion, and a metal electrode such as a silver electrode is provided on the other electrode 2. An electrolyte layer having silver or a compound containing silver in the chemical structure is supported between the electrode 1 and the electrode 2, and by applying positive and negative voltages between the counter electrodes, the electrode 1 and the electrode 2 are supported. A silver oxidation-reduction reaction is performed on the top, so that a black silver image in a reduced state and a transparent silver state in an oxidized state can be switched reversibly.

[Sulfur atom-containing compound]
In the electrolyte which concerns on this invention, it is preferable to contain the sulfur-containing compound represented by the said General formula (4) or General formula (5) with each structural material demonstrated above.

In the general formula (4), R ₇ and R ₈ each represent a substituted or unsubstituted hydrocarbon group, and these include a linear group or a branched group. Further, these hydrocarbon groups may contain one or more nitrogen atoms, oxygen atoms, phosphorus atoms, sulfur atoms, and halogen atoms. However, when a ring containing an S atom is formed, an aromatic group is not taken. Each element adjacent to the S atom is preferably a carbon atom.

  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, silver or a compound containing silver is solubilized by coexisting with a compound containing a chemical structural species that interacts with silver that causes a coordinate bond with silver or a weak covalent bond with silver. It is common to use a means for converting to. As the chemical structural species, a halogen atom, a mercapto group, a carboxyl group, an imino group, and the like are known. However, in the present invention, a thioether group is also useful as a silver solvent, has little influence on coexisting compounds, and is a solvent. It is characterized by high solubility in water.

  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.

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

  Next, the compound represented by the general formula (5) according to the present invention will be described.

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

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

  Examples of the nitrogen-containing heterocycle represented by Z in the general formula (5) 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. , A benzothiazole ring, a benzoselenazole ring, a naphthoxazole ring, etc., among which a triazole ring is preferable.

Examples of the halogen atom represented by R ₉ in the general formula (5) 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, and butyroyl groups. Examples of the arylcarbonyl group include a benzoyl group and an alkylbenzoyl group. Examples of the acyloxy group include acetyl group. Examples of the heterocyclic group include oxazole ring, thiazole ring, triazole ring, selenazole ring, tetrazole ring, oxadiazole ring, thiadiazole ring, thiazole group, and the like. Jin 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 include those having further substituents.

  Next, although the preferable specific example of a compound represented by General formula (5) is shown, this invention is not limited to these compounds.

  Among the above-exemplified compounds, Exemplified Compounds 5-12 and 5-18 are particularly preferable from the viewpoint that the object and effects of the present invention can be exhibited.

[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.

  In the present invention, silver or a compound containing silver in the chemical structure is preferably a compound represented by the following general formula (6) or (7).

General formula (6)
R ¹ —SO ₃ —Ag
General formula (7)
R ² —CO ₂ —Ag
In the formula, each of R ¹ and R ² represents an electron-withdrawing group, and represents a substituent having Hammett's substituent constant σ _m of +0.2 or more. More preferred is a substituent having a Hammett's substituent constant σ _m of +0.3 or more.

The Hammett substituent constant σ _m in the present invention refers to a numerical value representing the effect of the substituent on the acid dissociation equilibrium constant of the substituted benzoic acid.

Examples of the substituent represented by R ¹ and R ² that satisfy the conditions of the present invention include CBr ₃ , CCl ₃ , CF ₃ , CN, CHO, CONH ₂ , C═CH, CH ₂ SO ₂ CF ₃ , COCH. ₃ , CO ₂ CH ₃ , C═O (NHCH ₃ ), C═S (NHCH ₃ ), CF (CF ₃ ) ₂ , C (OH) (CF ₃ ) ₂ , CH═CHCN, CH═CHCHO, CO ₂ C ₂ H ₅ , CF ₂ CF ₂ CF ₂ CF ₃ , CH═CHCOCH ₃ , C ₆ Cl ₅ , C ₆ CF ₅ , OCF ₃ , OCHF ₂ , OSO ₂ CH ₃ , OCF ₂ CHFCl, OCOCH ₃ , OC ₆ H ₅ , OSO ₂ C ₆ H ₅ , POCl ₂ , PCl ₂ , POF ₂ , PF ₂ , PSCl ₂ , P (Cl) N (CH ₃ ) ₂ , PO (CH ₃ ) ₂ , PO (OCH ₃ ) ₂ , PO (C ₂ H ₅ ) ₂ , OCF ₂ CF ₂ H, 2-C ₅ H ₄ N, OSO ₂ CF ₃ , C (CF ₃ ) ₃ , pyrrole, CH═C (CN) ₂ , COOC ₆ H ₅ , C (OC) (CF ₃ ) _{2 and the} like.

  Typical specific examples of the compound represented by the general formula (6) are shown below.

  Of the compounds represented by the general formula (6) exemplified above, a particularly preferred compound is the exemplified compound (6-1).

  Next, typical specific examples of the compound represented by the general formula (7) are shown below.

  Of the compounds represented by the general formula (7) exemplified above, a particularly preferred compound is the exemplified compound (7-1).

In the general formula (6), the substituent R ¹ is preferably represented by the following general formula (8) or (9). In the general formula (7), the substituent R ² is represented by the following general formula (8). ) Or (9).

In the general formulas (8) and (9), n represents an integer of 0 or more, and R ^{3 to} R ¹⁰ satisfy the conditions as R ¹ and R ² in the general formulas (6) and (7), respectively. It is a substituent. Note that * indicates a binding position.

  Typical specific examples of the compound represented by the general formula (8) are shown below.

  Among the compounds represented by the general formula (8) exemplified above, particularly preferred compounds are the exemplified compounds (8-1), (8-2), (8-5) and (8-6).

  Next, typical specific examples of the compound represented by the general formula (9) are shown below.

  Of the compounds represented by the general formula (9) exemplified above, particularly preferred compounds are the exemplified compounds (9-1), (9-2), (9-5) and (9-6).

  The silver ion concentration contained in the electrolyte 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.

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

Formula (1)
0 ≦ [X] / [Ag] ≦ 0.01
The halogen atom as used in the field of this invention means an iodine atom, a chlorine atom, a bromine atom, and a fluorine atom. When [X] / [Ag] is larger than 0.01, X− → X ₂ is generated during the oxidation-reduction reaction of silver, and X ₂ easily cross-oxidizes with blackened silver to dissolve the 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.

  In the display element of the present invention, in addition to the above-described constituent elements, various constituent layers can be provided as necessary. For example, a layer containing a compound exhibiting electrochromic properties may be formed on the counter electrode, so that an element structure capable of color display can be taken.

(Electronic insulation layer)
In the display element of the present invention, an electrical 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 (fusion method) (particulate fusion of polymer fine particles or inorganic particles by using a binder, etc., and utilizing pores formed between particles), extraction method ( After forming a constituent layer with a solvent-soluble organic or inorganic substance and a binder that does not dissolve in the solvent, the organic 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.

[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 1006-7XIII
Plasticizer 27 XII 650 Right 1006 XII
Slipper 27 XII
Matting agent 28 XVI 650 Right 1008-9 XVI
Binder 26 XXII 1003-4 IX
Support 28 XVII 1009 XVII
〔substrate〕
Examples of the substrate that can be used in the display element of the present invention include polyolefins such as polyethylene and polypropylene, polycarbonates, cellulose acetate, polyethylene terephthalate, polyethylene dinaphthalene dicarboxylate, polyethylene naphthalates, polyvinyl chloride, and polyimide. Synthetic plastic films such as polyvinyl acetals and polystyrene can also be preferably used. Syndiotactic polystyrenes are also preferred. These can be obtained, for example, by the methods described in JP-A Nos. 62-117708, 1-46912 and 1-178505. Further, a metal substrate such as stainless steel, a paper support such as baryta paper and resin coated paper, and a support provided with a reflective layer on the plastic film, supported by JP-A-62-253195 (pages 29-31) The thing described as a body is mentioned. RDNo. 17643, page 28, ibid. No. 18716, page 647, right column to page 648, left column, and No. 307105, page 879 can also be preferably used. As these supports, those having resistance to curling due to heat treatment of Tg or less as in US Pat. No. 4,141,735 can be used. Further, the surface of these supports may be subjected to surface treatment for the purpose of improving the adhesion between the support and other constituent layers. In the present invention, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, and flame treatment can be used as the surface treatment. Furthermore, the support body described in pages 44 to 149 of publicly known technology No. 5 (issued by Aztec Co., Ltd. on March 22, 1991) can also be used. Furthermore, RDNo. 308119, page 1009, Product Licensing Index, Volume 92, P108, “Supports”, and the like. In addition, a glass substrate or an epoxy resin kneaded with glass can be used.

〔electrode〕
In the display element of the present invention, it is preferable that at least one of the counter electrodes is a metal electrode. As the metal electrode, for example, known metal species such as platinum, gold, palladium, silver, copper, aluminum, zinc, nickel, titanium, bismuth, and alloys thereof can be used.

  In the present invention, the metal electrode may take a configuration composed of two or more layers as required. The outermost surface of the metal electrode is preferably formed of a metal having a smaller ionization tendency than the metal contained in the polymer film from the viewpoint of electrode durability.

  As an electrode manufacturing method, an existing method such as an electrolytic plating method, an electroless plating method, a displacement plating method, a vapor deposition method, a printing method, an ink jet method, a spin coating method, or a CVD method can be used.

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

[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. The spacer in the present invention is a fine particle for controlling the gap between the counter electrodes, and for example, a microsphere made of glass, acrylic resin or silica used in a liquid crystal display or the like is used. Can do. Further, a fixed spacer having a surface coated with a thermoplastic resin is also preferably used. The average particle size of these microspheres is preferably in the range of 10 μm or more and 50 μm or less from the viewpoint of dispersion stability in the electrolyte, screen printing suitability, or display element characteristics.

  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 stage 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.

[Driving method of display element]
In the display element of the present invention, it is preferable to perform a driving operation in which silver black is precipitated by applying a voltage equal to or higher than the precipitation overvoltage, and silver black is continuously precipitated by applying a voltage lower than the precipitation overvoltage. By performing this driving operation, the writing energy can be reduced, the driving circuit load can be reduced, and the writing speed as a screen can be improved. It is generally known that overvoltage exists in electrode reactions in the electrochemical field. For example, overvoltage is described in detail on page 121 of “Introduction to Chemistry of Electron Transfer—Introduction to Electrochemistry” (published by Asakura Shoten in 1996). Since the display element of the present invention can also be regarded as an electrode reaction between the electrode and silver in the electrolyte, it can be easily understood that overvoltage exists even in silver dissolution precipitation. Since the magnitude of the overvoltage is governed by the exchange current density, it is possible to continue silver black precipitation by applying a voltage equal to or lower than the precipitation overvoltage after the formation of silver black as in the present invention. However, it is estimated that electron injection can be easily performed with little extra 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 memory function. For example, a circuit described in FIG. 5 of Japanese Patent Application Laid-Open No. 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, for example, door keys, 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, buses Card, cash card, credit card, highway card, driver's license, hospital examination card, electronic medical record, health insurance card, basic resident register, passport, electronic book, etc.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

<< Preparation of electrolyte solution >>
(Preparation of electrolyte solution 1)
Obtained by adding 100 mg of silver salt compound (Exemplary Compound 8-2) and 200 mg of Exemplified Compound 5-12 to a mixed liquid of 1.0 g of dimethyl sulfoxide and 1.5 g of Compound 1 below, and heating and dissolving. The electrolyte solution 1 was obtained by mixing 200 mg of a compound (Exemplary Compound A-5) having a group that interacts with precipitated silver.

  In addition, the ratio [Cl] of the molar concentration [X] (mol / kg) of chloride ions in the electrolyte solution 1 and the total molar concentration [Ag] (mol / kg) of silver of silver or a compound containing silver in the chemical structure ] / [Ag] was 0.02. The molar concentration of this chlorine atom and the total molar concentration of silver in the chemical structure containing silver or silver were measured by ion chromatography and inductively coupled plasma atomic emission spectrometry.

(Preparation of electrolyte solution 2)
In the preparation of the electrolyte solution 1, an electrolyte solution 2 was prepared in the same manner except that 0.01 g of polyvinyl butyral (BL-S manufactured by Sekisui Chemical Co., Ltd.) was added.

(Preparation of electrolyte solution 3)
In the preparation of the electrolyte solution 1, an electrolyte solution 3 was prepared in the same manner except that 0.1 g of polyvinyl butyral (BL-S manufactured by Sekisui Chemical Co., Ltd.) was added.

(Preparation of electrolyte solution 4)
In the preparation of the electrolyte solution 1, an electrolyte solution 4 was prepared in the same manner except that the example compound A-20 was used in place of the example compound A-5 as a compound having a group that interacts with precipitated silver.

(Preparation of electrolyte solutions 5-7)
In the preparation of the electrolyte solutions 1 to 3, the electrolyte solutions 5 to 7 were similarly used except that the exemplified compound B-9 was used instead of the exemplified compound A-5 as a compound having a group that interacts with precipitated silver. Was prepared.

(Preparation of electrolyte solution 8)
In the preparation of the electrolyte solution 3, an electrolyte solution 8 was prepared in the same manner except that the example compound C-1 was used in place of the example compound A-5 as a compound having a group that interacts with precipitated silver.

(Preparation of electrolyte solutions 9-11)
In the preparation of the electrolyte solutions 1 to 3, the electrolyte solutions 9 to 11 were the same except that the example compound C-26 was used instead of the example compound A-5 as a compound having a group that interacts with precipitated silver. Was prepared.

(Preparation of electrolyte solution 12)
In the preparation of the electrolyte solution 1, an electrolyte solution 12 was prepared in the same manner except that the example compound C-38 was used in place of the example compound A-5 as a compound having a group that interacts with precipitated silver.

(Preparation of electrolyte solution 13)
In the preparation of the electrolyte solution 12, an electrolyte solution 13 was prepared in the same manner except that the addition amount of the exemplified compound 5-12 was changed to 100 mg and 50 mg of the exemplified compound 4-2 was further added as a sulfur-containing compound.

(Preparation of electrolyte solution 14)
In the preparation of the electrolyte solution 12, the electrolyte 14 was prepared in the same manner except that the molar concentration of chlorine ions contained in the electrolyte was adjusted and [Cl] / [Ag] was changed to 2.60 × 10 ^−6. did.

(Preparation of electrolyte solution 15)
An electrolyte solution 15 was prepared in the same manner as in the preparation of the electrolyte solution 1 except that the compound having a group that interacts with precipitated silver (Exemplary Compound A-5) was removed.

(Preparation of electrolyte solution 16)
An electrolyte solution 16 was prepared in the same manner as the electrolyte solution 15 except that 0.1 g of polyvinylidene fluoride was added.

(Measurement of electrolyte viscosity)
About each prepared electrolyte solution, the viscosity (Pa * s) in 25 degreeC was measured using the vibration viscometer (FVM-80A by Yamaichi Electronics Co., Ltd.), and the obtained result is shown in Table 1.

<< Preparation of titanium oxide dispersion >>
(Preparation of titanium oxide dispersion 1)
In an aqueous solution containing 2% of polyvinyl alcohol (weight average molecular weight 3,000), 20% of titanium oxide (titanium dioxide CR-93 manufactured by Ishihara Sangyo Co., Ltd.) is dispersed with an ultrasonic disperser, and titanium oxide dispersion 1 is obtained. Prepared.

(Preparation of titanium oxide dispersion 2)
In N-methylpyrrolidone containing 3% polyvinylidene fluoride, 2.5% of a compound having a group that interacts with precipitated silver (Exemplary Compound B-9), titanium oxide (titanium dioxide CR- manufactured by Ishihara Sangyo Co., Ltd.) 93) 20% was dispersed with an ultrasonic disperser to prepare titanium oxide dispersion 2.

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

(Preparation of electrode 2)
A silver-palladium electrode (electrode 2) having an electrode thickness of 0.8 μm, a pitch of 145 μm, and an electrode interval of 130 μm is formed on a glass substrate having a thickness of 1.5 mm and a size of 10 cm × 10 cm by using a known method. Got.

<< Production of display element >>
(Preparation of display elements 1-14, 16, 17)
The above was applied by a blade coater on the electrode 2 bordered with an olefin-based sealant containing 10% glass spherical bead-shaped spacer having an average particle size of 40 μm as a volume fraction, and 3 ° C. at 80 ° C. Drying was performed for 30 minutes to form a white scattering layer having a thickness of 30 μm.

  Next, after spraying glass spherical bead-shaped spacers having an average particle diameter of 40 μm, the electrode 2 and the electrode 1 were bonded together and heated and pressed to produce an empty cell. The electrolytes 1 to 14, 15, and 16 were vacuum-injected into the empty cells, respectively, and the injection ports were sealed with an epoxy-based ultraviolet curable resin, and display elements 1 to 14, 16, and 17 were produced.

(Preparation of display element 15)
A display element 15 was produced in the same manner as in the production of the display element 16 except that the titanium oxide dispersion liquid 2 was used instead of the titanium oxide dispersion liquid 1.

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

(Evaluation of display unevenness resistance)
Each display element manufactured above is applied with a voltage of 1.5 V for 1.5 seconds to display white, and a voltage of -1.5 V is applied to display gray until the reflectance at 550 nm is about 30%. Then, the reflectance at 550 nm at any five locations of the display element was measured with a spectrocolorimeter CM-3700d manufactured by Konica Minolta Sensing Co., and the difference between the maximum value and the minimum value of the reflectance was calculated. The calculated difference in reflectance was ΔR _Glay, and ΔR _Glay was used as an indicator of display unevenness. Here, the smaller ΔR _Glay is, the better the display unevenness resistance is.

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

  As is clear from the results shown in Table 1, the presence of a compound having a group that interacts with the precipitated silver in the electrolyte or the white scattering layer can prevent migration of the precipitated silver and suppress the occurrence of display unevenness. Became possible. Also, the display speed was fast and good.

Claims (9)

A display element having an electrolyte containing at least 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, the counter electrode A display element comprising a compound having a group that interacts with silver deposited therebetween. The display element according to claim 1, wherein the compound having a group that interacts with the precipitated silver is a compound represented by the following general formula (1).

[Wherein, X _{1 to} X ₄ each represent —NR ₁ , —S— or —O—. R ₁ represents a bond for forming a double bond with a hydrogen atom or an adjacent atom. Y _{1 to} Y ₄ each represent CR ₂ or a nitrogen atom. R ₂ represents a bond for forming a double bond with a hydrogen atom or an adjacent atom. Z _{1 to} Z ₄ each represents an atomic group for forming a heterocyclic ring together with X _{1 to} X ₄ and Y _{1 to} Y ₄ . Heterocycle formed by Z ₁ , X ₁ and Y ₁ , Heterocycle formed by Z ₂ , X ₂ and Y ₂ , Heterocycle formed by Z ₃ , X ₃ and Y ₃ and Z ₄ , X ₄ And the heterocycle formed by Y ₄ may have a substituent, and may form a condensed ring. L represents a linking group or a simple bond between the heterocyclic ring formed of Z ₂ , X ₂ and Y ₂ and the heterocyclic ring formed of Z ₄ , X ₄ and Y ₄ . ] The display device according to claim 2, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2).

[Wherein, R _{3 to} R ₆ each represent a substituent. Moreover, R < ₃ > -R < ₆ > may have another substituent, respectively. L represents a linking group or a simple bond between two bipyridine groups. ] The display element according to claim 1, wherein the compound having a group that interacts with the precipitated silver is a compound represented by the following general formula (3).

[In the formula, A is

(Wherein x represents an integer of 1 to 20, and y represents an integer of 1 to 60)
B represents an oxygen atom, a methylene group, an alkylene group, an alkyleneoxy group, a phenyleneoxy group or a simple bond. ] 5. The display element according to claim 1, wherein the electrolyte has a viscosity at 25 ° C. of 0.01 Pa · s or more and 5.0 Pa · s or less. 6. The display element according to claim 1, wherein the compound having a group that interacts with the precipitated silver has a weight average molecular weight of 2,000 or more and 10,000 or less. The display element according to claim 1, wherein the compound having a group that interacts with the precipitated silver is adsorbed on titanium oxide. The display element according to any one of claims 1 to 7, wherein the electrolyte contains a compound represented by the following general formula (4) or general formula (5).
General formula (4)
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 8, wherein a condition defined by the following formula (1) is satisfied when the mole / kg) is satisfied.
Formula (1)
0 ≦ [X] / [Ag] ≦ 0.01