JPS6355047B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses titanic acid, stannic acid,
Either one or a mixture of two or more selected from antimonic acid, zirconic acid, and silicic acid is used, or a proton conductive solid and the aforementioned titanic acid, stannic acid, zirconic acid, antimonic acid, niobic acid, tantalic acid, and silicic acid are used. It relates to a product that uses one or a mixture of two or more selected from acids and further contains a polyhydric alcohol if necessary. Since these compounds are easily available as white powders, their use as electrolytes reduces costs and provides clear, high-contrast displays on white substrates.

Furthermore, since these compounds themselves are proton conductors, the color density and response speed are also improved. Moreover, these compounds are obtained as powders,
Since it can be made into an ink, it can be easily formed into a layer by applying it, for example, by screen printing, and an electrochromic display with a simple cell structure and easy to produce can be obtained.

Traditionally, transition metal oxides that form electrochromic bodies include titanium oxide (TiO ₂ ), nickel oxide (NiO or Ni ₂ O ₃ ), cerium oxide (CeO ₂ ), and vanadium pentoxide (V ₂ O ₅ ). , iridium oxide (Ir ₂ O ₃ ), rhodium oxide (Rh ₂ O ₃ ), niobium oxide (Nb ₂ O ₅ ), tantalum oxide (Ta ₂ O ₅ ), chromium oxide (Cr ₂ O ₃ ), molybdenum oxide (MoO ₃ ), tungsten oxide (WO ₃ ), manganese dioxide (MnO ₂ ), rhenium oxide (Re ₂ O ₇ ), osmium oxide (OsO ₄ ), and cobalt oxide (Co ₂ O ₃ ), among others. _WO3 , _MoO3 , _TiO2 , _{Ir2O3 ,}
Rh ₂ O ₃ , NiO, V ₂ O ₅ and the like are used. When a display element made of a transition metal oxide such as tungsten oxide is used as an electrochromic material, when combined with an electrolyte such as sulfuric acid with a concentration of 0.1, it can turn blue by applying a voltage. Electrochromic displays in which a tungsten oxide layer develops color are known. However, when using an electrolyte, it is necessary to prevent leakage, which complicates the structure of the cell.Furthermore, there are disadvantages such as dissolution of the electrochromic layer such as tungsten oxide, so it is difficult to solidify the electrolyte. It is desired to do so. From this standpoint, for example, JP-A-53-
As seen in Japanese Patent No. 12348, it has been proposed to use an acid addition salt of hexamethylenetetramine and sulfuric acid in a known proton-conductive solid electrolyte layer. Since this proton conductive solid is a white crystal, when used in an electrochromic display, a vivid blue display can be obtained on a white background.
However, since its proton conductivity is low, when trying to make the electrolyte layer thinner to increase responsiveness,
The color of the anode electrode becomes fainter and the color density of the base increases, making it necessary to increase the whiteness. The use of white pigments has long been considered in order to make displays appear more vivid;
There is one in which titanium oxide (TiO ₂ ) is added to the electrolyte, as seen in Japanese Patent No. 99057. However, TiO ₂ is an insulator and its specific resistance is 1×10 ⁸
The resistance is quite high (Ω/cm), and when the resistance is low like an electrolytic solution, adding TiO ₂ does not have a large effect on the response, but it is difficult to add TiO 2 to a proton-conducting solid electrolyte made of hexamethylenetetramine and sulfuric acid. Since its proton conductivity is low, adding TiO ₂ increases the brightness of the display but reduces the responsiveness.

In view of the above circumstances, the present invention has been developed based on various studies aimed at increasing whiteness without reducing proton conductivity. Acid and silicic acid are white powders that are effective in increasing the whiteness of the base, and they themselves exhibit proton conductivity and have a low resistance value of 1 x 10 ⁴ to 1 x 10 ⁵ Ω/cm. It has been found that the addition of these additives does not impair color development response and improves both reaction response speed and color development density.
In addition, a small amount of a binder used in printing ink is added to each of titanic acid, stannic acid, zirconic acid, antimonic acid, niobic acid, tantalic acid, and titanic acid to form a layer adjacent to a transition metal oxide layer represented by tungsten oxide. Even when a voltage was applied to the laminated material printed and coated with the material, a blue color was obtained, and it was also found that the material itself is effective as an electrolyte for electrochromic displays.

Although detailed studies have been reported regarding these compounds used in the present invention, the results are not yet certain. Titanic acid is represented by H ₄ TiO ₄ and has an indeterminate amount of water attached to it. TiO(OH) ₂・nH ₂ O
There is also a report that TiO(2-x)(OH) _2x・yH ₂ O (x>1). There is also a report that there are 3 protons per 10 titanium atoms.

Stannic acid is orthostannic acid H ₄ SO ₄ , metastannic acid
H ₂ SnO ₃ Hexahydroxostannic acid H ₂ [Sn
(OH) ₆ ], but recently SnO ₂ and
Also written as xH ₂ O, the water is (1) Adhering water: 200℃
It is desorbed below, but it connects to the surface and pores, and its amount varies depending on the preparation method. (2) Bound water: It binds to the parent body through hydrogen bonds and desorbs at 200 to 400°C. (3) Structured water: 400
It has also become clear that the strength of water's bond changes continuously, such as desorption at temperatures above ℃.

Antimonic acid is orthoantimonic acid
H ₃ SbO ₄ , metaantimonic acid HSbO ₃ , pyroantimonic acid (diantimonic acid) H ₄ Sb ₂ O ₇ ), triantimonic acid H ₅ Sb ₃ O ₁₀ , etc., but Sb ₂ O ₃ xH ₂ O
It is sometimes written as Sb ₂ O ₅ xH ₂ O. 1
It has been found that there is one hydroxyl group and one free water in the antimony atom, and according to X-ray diffraction, the crystalline one is {[H ₃ Sb ₃ O ₅ (OH) ₈ ]} ₃
It has the composition [H ₅ Sb ₅ O ₆ (OH) ₁₈ ], and is known to have a unit cell containing 14 exchangeable hydrogen atoms.

Zirconic acid is written as Zr(OH) ₄ xH ₂ O, and according to the facultative properties of hydroxides of other group elements,
Although this can be considered an acid, it has few acidic properties. Tantalum acid is given the form HTaO ₃ , but an indeterminate amount of water is added to it to form Ta ₂ O ₅・nH ₂ O
is written. Niobic acid is written as Nb ₂ O ₅ xH ₂ O.

Silicic acid includes orthosilicic acid H ₄ SiO ₄ and metasilicic acid.
There are H ₂ SiO ₃ , meso disilicic acid, H ₂ Si ₂ O ₅ , meso trisilicate H ₄ Si ₃ O ₈ , meso tetrasilicate H ₆ Si ₄ O _4, etc., but you can obtain one with exactly this composition. It is difficult to obtain as a white powder. All of the above compounds are readily available as white powders.

Titanic acid, stannic acid, antimonic acid, zirconic acid, tantalic acid, niobic acid, and silicic acid are in the state of hydrated substances, but the water is chemically bonded and the surface is covered with water and is a proton conductive solid. Although it has properties as an acid, it is also effective as an electrolyte for electrochromic displays without leaving transition metal oxides; , which is different from niobium oxide mixed with water.

In addition, solid electrolytes for electrolyte layers such as titanic acid, stannic acid, antimonic acid, zirconic acid, tantalic acid, niobic acid, and silicic acid have a vapor pressure of 0.1 mmHg or less at 20°C, especially 0.05 mmHg or less, and are normally liquid. Since polyhydric alcohols can be contained, the conductivity under low humidity conditions can be further significantly improved. The reason for this appears to be that these polyhydric alcohols act to reduce the dissociation energy of protons. There is a certain suitable range for the amount of polyhydric alcohol used, and it is 0.5 to 30% based on the solid content, which is the main component of the electrolyte layer.
In particular, it is preferable to use the amount in the range of 5 to 20%; outside this range, the conductivity tends to decrease, and the film strength also decreases.

The polyhydric alcohol has the formula HO-(R-O)- _o H (wherein, R is an alkylene group having 2 to 10 carbon atoms, n is a number of 1 or more, and n is a polyhydric alcohol. Glycols, glycerin, diglycerin, and the like represented by (selected as follows) are preferably used.

Examples of suitable glycols are:
Ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol with n = 5 or more (molecular weight 400 or less), propylene glycol, dipropylene glycol, polypropylene glycol with n = 3 or more (molecular weight 40 or less), butylene-1.4 - Glycol, hexylene glycol, octylene glycol, etc. can be used. Note that normally solid polyhydric alcohols such as pentaerythritol, mannitol, sorbitol, and glycose do not have the effect of improving conductivity under low humidity.

An example of the structure of the electrochromic display body of the present invention is shown in FIG. An example of a patterned transition metal oxide layer is a tungsten oxide layer. In order to prevent electrical leakage, an insulating layer 4 is provided in a non-displayed area, and an electrolyte layer 5 is formed on the insulating layer 4 using titanic acid, stannic acid, antimonic acid, zirconic acid, niobic acid, tantalic acid, silicic acid, or a mixture thereof. Further, a mixture of proton-conductive solid is coated, and a counter electrode 6 is provided on top of the coating.

By applying a voltage between the two electrodes, the water chemically bonded to the metal oxide easily releases protons, causing the tungsten oxide layer to undergo reduction and color development. The present invention has higher proton dissociation and higher mobility than conventional solid electrolyte type electrochromic displays, so it is possible to obtain extremely high response speed and high color density. Then, when a reverse voltage is applied, the coloring layer is quickly decolored.

Although the explanation has been mixed, titanic acid, stannic acid, antimonic acid, zirconic acid,
Examples of proton conductive solids that can coexist with niobic acid, tantalic acid, silicic acid, etc. and serve as the main component of the electrolyte layer are acid addition salts in which the acid component is sulfonic acid and the base component is urea. Proton conductive solids can be mentioned, and specific examples thereof are as follows.

(1) Urea to P-toluenesulfonic acid mixed molar ratio (1:1.2) (2) Urea to benzenesulfonic acid mixed molar ratio (1:1.2) (3) Urea to phenolsulfonic acid mixed molar ratio (1:1.2) The invention will be explained in more detail in the following examples.

Example 1 A transparent electrode of indium oxide was provided in a pattern on a glass substrate, and tungsten oxide was vacuum-deposited thereon to a thickness of about 0.5 μm by electron beam heating. Next, an insulating layer made by Toyo Ink Mfg. Co., Ltd. under the trade name SS-2500 was provided on the non-display area by screen printing.

Next, as an electrolyte, metastannic acid (Mitsuwa Chemicals 15% loss on ignition) and glycerin were used in a weight ratio of 4:1.
When the mixture was mixed and sandwiched between opposing electrodes made of molybdenum and a voltage of 1 to 2 V was applied between both electrodes, a blue color was obtained on the white background.

Example 2 A transparent electrode and a tungsten oxide layer were provided on a glass substrate, and an insulating layer of Toyo Ink Mfg. Co., Ltd. trade name SS-2500 was provided on the non-display area by screen printing, and a counter electrode made of molybdenum. The molar ratio of urea/P-toluenesulfonic acid between 1:
1.2 solid electrolyte mixed with metastannic acid, glycerin, and a binder (styrene-acrylic copolymer emulsion trade name Torcryl K-70 [Toyo Ink Manufacturing Co., Ltd.]) in a weight ratio of 1.6:0.4:0.3:0.3. A voltage of 1.3V was applied to this. The color density at this time is 5 seconds after energizing.
It became 0.4. On the other hand, in the case of a cell prepared without adding metastannic acid, it took 15 seconds to obtain a color density of 0.4 when 1.3V was applied, resulting in a three-fold increase in response speed. In addition, the whiteness of the base was improved, and the brightness of the display was greatly increased, making it easier to see.

[Brief explanation of drawings]

FIG. 1 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... Insulating layer, 5... Electrolyte layer, 6... Counter electrode.

Claims (1)

[Scope of Claims] 1. In an electrochromic display body comprising at least an electrochromic body layer made of a transition metal oxide and an electrolyte layer between a transparent patterned electrode and a counter electrode, as a main component of the electrolyte layer. An electrochromic display characterized by using one or a mixture of two or more selected from titanic acid, stannic acid, antimonic acid, zirconic acid, niobic acid, tantalic acid, and silicic acid. 2. In an electrochromic display comprising at least an electrochromic body layer made of a transition metal oxide and an electrolyte layer between a transparent patterned electrode and a counter electrode, titanic acid or stannic acid is used as the main component of the electrolyte layer. , antimonic acid, zirconic acid, niobic acid, tantalic acid, and a mixture of two or more selected from silicic acid and a proton conductive solid. . 3. The electrochromic display according to claim 1, in which 0.5 to 30 weight percent of polyhydric alcohol, which has a vapor pressure at 20°C of 0.1 mmHg or less and is normally liquid, is added to the main component of the electrolyte layer. . 4. The electrochromic display according to claim 2, in which 0.5 to 30 weight percent of polyhydric alcohol, which has a vapor pressure at 20°C of 0.1 mmHg or less and is normally liquid, is added to the main component of the electrolyte layer. .