JPH0115852B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention comprises a reversibly oxidizable electrode that assists electrochemically reversible color development as a counter electrode (anode) constituting a solid-state electrochromic display that does not use an electrolyte. Specifically, carbon powder is used as a conductive filler, a synthetic resin binder, a reversible oxidizing substance, and a volatile solvent are added to this, and the mixture is kneaded into an ink, which is then applied and formed to form a counter electrode layer. This invention relates to a chromic display with improved reversible coloring and fading characteristics.

As electrochromic display materials, there are those using the electrochemical coloring phenomenon of thin film tungsten oxide, as disclosed in U.S. Patent No. 3,521,941 and Japanese Unexamined Patent Publication No. 13891/1982, and those using viologen derivatives as disclosed in Japanese Unexamined Patent Publication No. 1562/1982. What was used is shown.

For example, as shown in FIG. 1, a thin layer of transparent electrodes 2 is provided on a transparent substrate 1 such as glass so as to match the desired pattern, and an electrode made of the above-mentioned tungsten oxide or viologen derivative is placed on a transparent substrate 1 such as glass. Chromic body layers 3 are laminated, a counter electrode 6 is disposed via a light scattering plate 5, etc., and a sealing cover 11 is formed so that necessary parts are contained in the electrolyte 4, that is, the electrolytic solution.

Various materials such as reduced tungsten oxide, platinum, and carbon have been disclosed as counter electrode materials for these electrochromic displays.
However, there are problems such as insufficient stability of the material, instability of the applied voltage, and electrochemical dissolution in the electrolyte solution, which may deposit on the display electrode. In addition, JP-A-49-30519 and JP-A-50-136000 disclose the presence of an auxiliary redox in the form of Fe ⁺² Fe ⁺³ to facilitate electrochemical color development; The presence of a complexing agent is disclosed. The above conventional invention facilitates electrochemical color development by using an auxiliary redox system in the electrolyte, but
JP-A-55-17115 and JP-A-55-69127 also disclose the use of an auxiliary redox system as a counter electrode instead of in the electrolyte.

This Japanese Patent Application Publication No. 55-17115 and Japanese Patent Application Publication No. 55-69127
In the publication, hydroquinone derivatives and iron berlinate derivatives are used as reversible oxidizing substances, and electrolytes in contact with these, such as potassium bromide dissolved in water or lithium perchlorate dissolved in propylene carbonate, are used as reversible oxidizing substances. It is made by heat and pressure molding with thermoplastic resin, carbon, and a reversible oxidizer conductor so that it is inert, i.e., does not dissolve.

However, in an electrochromic display as shown in Fig. 1, an electrolyte solution such as 0.1N sulfuric acid or lithium perchlorate dissolved in propylene carbonate is used as the electrolyte 4 as a proton or cation donor. Therefore, it is preferable to use a material that is inert to this electrolytic solution.If the counter electrode that can be reversibly oxidized is dissolved in this electrolytic solution, the display will become unclear due to coloring of the electrolytic solution. As a result, the reversibly oxidizable substance and binder are limited to those insoluble in the electrolyte, and the structure of the counter electrode has become complex, requiring pressure molding on the current collector.

The present invention relates to a system in which this auxiliary redox is used as a counter electrode, and it is possible to fabricate this auxiliary redox-based electrode easily and by a simple method, and to simplify the cell structure. Furthermore, it is possible to select materials without being limited to conditions such as insolubility in aqueous solvents and non-aqueous solvents (electrolyte solutions).

The present invention is based on a patent application previously proposed by the present inventors in 1982.
Based on the fact that the solid electrolyte shown in No. 26358 shows good proton conductivity and can be easily laminated on an electrochromic layer by printing methods such as screen printing, we also developed a counter electrode that can be reversibly oxidized. By laminating the solid electrolyte layer on a solid electrolyte layer using a printing method such as screen printing, it is possible to easily manufacture a cell with a simple structure. The following will explain the embodiment of the present invention shown in FIG.

The transition metal oxides constituting the electrochromic layer 3 of the present invention include TiO ₂ , NiO, Ni ₂ O ₃ ,
_CeO2 , _{V2O5 , Ir2O3 , Rh2O3 , Nb2O5 , Ta2O5 ,
Cr2O3 , MoO3} , _WO3 , _MnO2 , _Re2O7 , _{OsO4 ,}
Co ₂ O ₃ etc., preferably WO ₃ , MoO ₃ ,
These include TiO ₂ , Ir ₂ O ₃ , Rh ₂ O ₃ , NiO, V ₂ O ₅ and the like.

These transition metal oxides are laminated on a transparent electrode 2 made of tin oxide or indium oxide containing tin oxide, which is patterned on a transparent substrate 1 such as glass, to form an electrochromic layer 3.

The solid electrolyte layer 7 laminated thereon includes salts such as urea-P toluenesulfonic acid and hexamethylenetetramine-sulfuric acid, proton conductive solids such as phosphotungstic acid, titanic acid, stannic acid antimonic acid, and zirconic acid. , niobic acid, tantalic acid and silicic acid or a mixture of two or more selected from titanic acid, stannic acid, antimonic acid, zirconic acid, niobic acid, tantalic acid and silicic acid as a proton conductive solid. One selected type or a mixture of two or more types can be used. These can constitute a solid electrolyte layer by themselves, or may be constituted as a printed layer by adding a small amount (30% by weight or less) of polyhydric alcohol, synthetic resin emulsion, or the like.

Further, a cationically conductive solid such as a Na-β-alumina substrate can also be used.

The composition of the ink for producing the reversibly oxidizable counter electrode layer 9 of the present invention, which is laminated on the solid electrolyte layer 7, includes carbon powder, a synthetic resin binder, a reversible oxidizing substance, a volatile solvent, and, if necessary, improved printability. There are more additives to make it stronger. Examples of the carbon powder include carbon blacks such as butcher black, acetylene black, and conductive furnace black, as well as carbon fibers.

Examples of binders used as binders include acrylic resins, vinyl chloride resins, epoxy resins, melamine resins, guanamine resins, alkyd resins, and methacrylic resins. Examples of reversible oxidizing substances include titanium dioxide, nickel oxide, and oxidized Cobalt, iron oxide, silicon dioxide, lead oxide, copper oxide (CuO), iron sulfide (FeS, FeS ₂ ), bismuth oxide (Bi ₂ O ₃ ), niobium sulfide, and other metal oxides and sulfides Pyrophosphate No. 1 Tin, Japanese Unexamined Patent Publication No. 55-17115,
Examples include hydroquinone derivatives and iron berric acid derivatives disclosed in JP-A-55-69127.

Preferably, the volatile solvent has a high boiling point, so that it will not evaporate during printing processes such as screen printing and change the ink composition, and that dries quickly after printing.
150℃ or higher, 270℃ or lower, preferably 200℃ or higher250
℃ or below, and must be a true solvent for the binder.Diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, 2-phenoxyethanol, 2-
Examples include hexyloxyethanol, N-methylpyrrolidone, and 2-pyrrolidone.

Furthermore, a surfactant may be used as an additive in order to improve the suitability for printing and coating.

The counter electrode layer 9 of the present invention can be laminated by simply printing and has a simple structure.

Further, on this reversibly oxidizable counter electrode layer 9,
The color responsiveness is improved by using metal powder as a conductive filler, adding a synthetic resin binder and a volatile solvent to the ink, kneading it, applying it, drying and laminating it. This is because the reversibly oxidizable substance has no conductivity, and adding it causes a voltage drop at the counter electrode. By stacking the above-mentioned conductive layer 10 on the counter electrode layer 9, the voltage drop disappears and responsiveness increases. It is thought that this will improve. Ag, Pd, Ni, Cu, etc. can be used as the metal powder.

The present invention is as described above, and according to the present invention, compared to the conventional display body as shown in FIG. In addition, there is no risk that the material constituting the counter electrode, particularly the reversible oxidizing substance, will dissolve during energization, resulting in stable display and improved lifespan.
In particular, the counter electrode of the present invention can be formed by simply using an ink as a coating layer, and its ease of manufacture is superior to conventional counter electrodes that use electrolytes.

Furthermore, in the case of a solid electrolyte layer display that does not use an electrolytic solution as shown in Fig. 2, those in which the counter electrode can be reversibly oxidized as in the present invention have a longer time required for color development and fading than those in which the counter electrode is not oxidized. However, it will be shortened to about 1/3 to 1/5. (Assuming the applied voltage is the same, of course) Also, uneven coloring is less likely to occur,
The number of repetitions of color development and fading (life span of the display) is also extended by about 10 times, and the present invention is extremely excellent in that it has both ease of manufacture and excellent performance.

The invention will be explained in more detail in the following examples.

Example 1 As shown in FIG. 2, a transparent electrode 2 made of indium oxide is provided in a pattern on a transparent substrate 1 made of glass, and an electrochromic layer 3 made of tungsten oxide is further formed thereon by electron beam heating. Vacuum deposition was performed to a film thickness of approximately 0.5 μm.

Next, the non-display area is printed using an epoxy synthetic resin enamel with the product name of Toyo Ink Mfg. Co., Ltd.
An insulating layer 8 of SS-25000 was provided.

Next, metastannic acid (Mitsuwa Chemicals, scorching heat loss 15
%), glycerin, binder (styrene acrylic copolymer emulsion trade name Torcryl K-70)
[Toyo Ink Manufacturing Co., Ltd.]) and water in a weight ratio of 6:1:
After printing the ink mixed at a ratio of 0.2:1 on the entire surface by screen printing method, it was heated at 60℃30
The solid electrolyte layer 7 is formed as a printed layer by drying for several minutes, and the counter electrode layer 9, which can be reversibly oxidized, is made of powder, phenol-modified xylene resin, triiron tetroxide, acetylene black, and diethylene glycol monoethyl ether. Acetate was kneaded into an ink at a weight ratio of 0.3:1:3 and applied by screen printing, dried at 60°C for 30 minutes, and then used as a conductive layer under the trade name Dotact XA-167 (Fujikura Kasei Co., Ltd.). is applied in a layered manner on top to form an electrochromic display, and ±
Even though 1.3V was applied for 1 second, a good reversible color development/discoloration phenomenon was obtained, and compared to conventional products, the applied voltage was lower and the time required for color change was also shortened.

Example 2 As the ink for forming a reversibly oxidizable counter electrode in Example 1, Prussian blue (trade name: Konsei AF [Dainippon Seika Co., Ltd.]), phenol-modified xylene resin, Ketsutien black, and diethylene glycol monobutyl ether were used at a weight ratio of 0.6. : Kneaded ink at a ratio of 1:1:4, used in Example 1
Similar good results were obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a conventional electrochromic display, and FIG. 2 is a schematic sectional view showing an embodiment of the electrochromic display of the present invention. DESCRIPTION OF SYMBOLS 1... Transparent substrate, 2... Transparent electrode, 3... Electrochromic body layer, 4... Electrolyte, 5... Light scattering plate, 6... Counter electrode, 7... Solid electrolyte layer,
8... Insulating layer, 9... Reversible oxidizable counter electrode layer, 10... Conductive layer, 11... Sealing cover.

Claims (1)

[Claims] 1. An electrochromic material layer comprising at least an electrochromic material layer made of a transition metal oxide and a solid electrolyte layer between a transparent patterned electrode and a counter electrode to cause electrochemically reversible coloring. In the solid electrolyte layer, the solid electrolyte layer is a printed layer containing at least one selected from titanic acid, stannic acid, antimonic acid, zirconic acid, niobic acid, tantalic acid, or silicic acid as a main component; The electrode is a reversibly oxidizable counter electrode layer that assists color development, and carbon powder is used as a conductive filler, and a synthetic resin binder, a reversible oxidizing substance, and a volatile solvent are added to this and kneaded to form an ink, which is coated on a solid electrolyte. An electrochromic display body characterized in that it is provided as a coating layer on. 2. On the reversibly oxidizable counter electrode layer, metal powder is used as a conductive filler, a synthetic resin binder, and a volatile solvent are added to form an ink, which is then kneaded, coated, dried, and further laminated to form a conductive layer. An electrochromic display according to claim 1.