JPS58209721A - Electrochromic display material - Google Patents

Abstract

PURPOSE:To provide a plate-like body having flexibility and elasticity and to reduce impurities by adding an active material contg. W18O49 or W20O55 or the like, carbon and further a fibrillated fluororesin under stirring and making polytetrafluoroethylene thoroughly fibrous. CONSTITUTION:Metallic tungsten powder and tungsten trioxide powder are mixed in a ratio of WO2.9 and the mixture is vacuum sealed in a quartz tube, whereafter the tube is heat treated for 10hr at 800 deg.C, whereby the crystal of W20O58 is obtd. The material is ground and is mixed as an electrode active material at 1:1wt. ratio with acetylene black. A dispersed soln. of fibrillated polytetrafluoroethylene is further added at 20% based on weight to said mixture and a small amt. of ethanol is added thereto under mixing and stirring. The mixture is molded with rolls to a sheet of 200mum thickness. When the specimen of the counter electrode material prepd. in such a way is used as a counter electrode 7 in an EC display, there is virtually no potential drift and the potential drift is within + or -100mV even after 1,000hr at 80 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is based on an electrochromic film that exhibits a coloring/decoloring phenomenon when pressure is applied. (hereinafter abbreviated as Tj2G) relates to a display body that utilizes material knowledge, and more specifically relates to the 7" direction used in the display body.

P2C display H, Th'1 The structure shown in Figure 1 is broken, and a transparent conductive film (2) whose main component is indium oxide or tin tyride is formed on one surface of a transparent substrate (1) that is the display side substrate. is formed into a predetermined pattern, and an EC layer (8
) is formed. Furthermore, if necessary, the gc of the display side board
An insulating film (4) of silica, alumina, etc. is formed on a part of the surface not covered by the layer. A conductor (6) is formed on the inner wall of a counter substrate (6), which is another substrate disposed opposite to the transparent substrate, and a counter electrode (?) is arranged on the conductor (6). The pair of substrates (1) and.

Conventionally, the same gem as that used for the display electrode was used as this counter electrode, and it was known that the structure was symmetrical on the front and back, so it was called a symmetric element.
In this case, the EC/Zeng to be used as the counter electrode is placed in advance with a shield 9.

When a voltage is applied between the display electrode and the display electrode, it is necessary to make sure that the frost and the load are easily moved and the display is colored smoothly. Moreover, when used for a long period of time, the mold has been designed to keep this coloring state constant so that the display is always performed according to the movement conditions of one pair, but this is technically quite difficult, and the drive The circuit had to become complicated.

Another conventionally known pairing rod is carbon, which is a material that is vapor chemically stable and has a large specific surface area. In this case, in order to increase the stability of one position as a counter electrode, the force.

It is common to add 4i + i active substances, and for this reason W
Os powder is used.

In yet another example, the following 'Yamamoto-ku' active material is used instead of WOa powder.

Manganese dioxide, Prussian blue, Fed.

Fe20a, NbaOi, 1ib
20s, TiO2, Tiz03.

Mo5s, MO82, Li2WO4, Sr+0
2, PbO, rzOx.

IrO2, Cu2O, CuO, Bit's, B
i2's, V2O3.

V20a, '1-time phthalonanine, cobalt complex,
Iron complex, 5nSe, Ti5z.

Although the properties of WOa powder as an active material are improved compared to the case of using carbon alone, the fluctuation of the electrode box and position when voltage is applied is large (11: position fluctuation), and it is still not sufficient. I could not say it. In this respect, most of the above-mentioned compounds are not much different from Wow powder and cannot be said to be particularly effective. Another problem is heat resistance. For example, iron complexes such as Prussian blue do not exhibit sufficient stability at temperatures above 150°C;
This was a problem because it was commonly used as the curing temperature for thermosetting sole materials used in the production of 1dEC displays.

Still other problems occur when a counter electrode made of carbon and an active material is used in an EC display. That is, when the display is stored at a high temperature (about 80° C.), a drift phenomenon (potential drift) of the electrode potential over time may occur, which may change the response performance of the EC display.

For example, manganese dioxide, especially electrolytic manganese dioxide, which is usually classified as r-manganese dioxide, has little potential fluctuation and is a very good active material, and has been reported in many cases. However, P2C displays equipped with counter electrodes made of carbon and manganese dioxide tend to generate potential drift and generally slow coloring response during storage at 80"C. These changes occur in relatively low Y crystals. Therefore, it must be considered that the change in the speed m is occurring gradually.

When using the EC display body for a long time, γ-MnOz
This potential instability, which can be seen in , poses a practical problem. Although the cause of this potential drift is not clear, it is thought to be due to a reaction between toI* and a component in the mask, and is irreversible. In this way, potential change 1! The search for active materials with low ν1 and low drift at the 'j41 position is extremely important for the practical application of EC displays. The present invention was made against this background, and is concerned with an attachment that exhibits excellent stability in terms of the active material value of the counter electrode. Again. ζAnother object of the present invention is to satisfy the above condition (1) and at the same time,
By setting the electric potential that the counter electrode shows at the top of the EC display to a desired value, the relationship between the coloring/decoloring speed of the BGO display and the voltage applied from /'j'fb is optimized. This simplifies the external 1/1 route and reduces power consumption. The goal is to make it possible.

The counter electrode used in the present invention is mainly composed of a conductive powder represented by carbon and a non-chemical tungsten compound having semiconducting properties, and if necessary, a fluororesin is used as a binder. added.

The non-chemical and theoretical tungsten/1#'' compound mentioned here is
Totomi, W. Tungsten oxide having the compositions ofofi8 and wL804+1 is a cheap material that can be easily combined with W and WO3.

This material has a lower Wm than WO3 powder, almost no potential drift It even inside the EC coating water, and exhibits extremely good performance. It's a trench, W1
In order to adjust the polar potential shown by 804° or W2° OH to the desired value, it is usually better to add paulownia wood, which exhibits a positive or negative polar potential, rather than this phase material. In this case as well, of course, a phase material must be selected that exhibits small 1-position fluctuations and little potential drift. As a result of examining the benefit t1 of this tank, it was found that the vanadium oxide powder represented by V2O5 is wu o4o or W. It is suitable for changing the potential of OI+8 by about 100 to 500 mV, and powder of PANADIUM MBRO/Z, which is Li x V z Os (0≦x<1), is
About 100-500mv, with a weight of 2005g.
It was found to be suitable for oxidation.

The addition of γ-MnOz also causes W Hg 04' in this case.
The mixture of @/MnO2 had a thick potential drift, which was a practical problem. Addition of V2O5, LixVzOs (jj &; l: , 7 each, 5 to 50 mol
2 (d) in section e (for omniscience).

Method 1 is to create a counter electrode using these active materials, but practical soil is extremely necessary. It is necessary that the KC display body does not deteriorate even if the coloring/decoloring reaction is repeated at least 106 times or more.For this purpose, unnecessary side reactions occur in the counter electrode t and the parts used, and the EC There are known negative effects that may cause discoloration of the film, foaming, etc.
However, care must be taken to control its purity.While keeping these points in mind, we have determined the temperature, air resistance, and mechanical strength necessary for the counter electrode, as well as the degree of frost, temperature fluctuation, and It is not necessarily possible to keep the degree of positional drift within a predetermined range using conventional techniques, and in fact, five unique efforts have been made.

As for the method known so far, JP-A +1i44
7-1.3891, a bead-like short aggregate of polymethyl methacrylate, a synchrohexyl phthalate plasticizer, Kuroyu'2, and PTF colloidally dispersed in water.
Fi 1 Add tungsten oxide or molybdenum oxide as an additive to finely powdered polyhexafluoropropylene/tetrafluoroethylene copolymer, and add these to 100~
After mixing on a rubber mixer preheated to 110°C and forming a thin plate, two small plates of this plate were placed between both sides of the tantalum metal mesh to press IJV.

A method is disclosed.

In this method, after molding, it is necessary to extract the polymethyl methacrylate plasticized with acetone in a tank, and it is also necessary to wash it afterwards, making it a rather complicated process in practice.

In the present invention, in view of these points, in addition to the active material containing W, 8O4°, or WtoOss, and carbon, a fibrillating fluororesin, specifically, a fibrillating fluororesin! j; By adding polytetrafluoroethylene and stirring the mixture to sufficiently fiberize the polytetrafluoroethylene, it is possible to form a plate-like body having flexibility and elasticity in the subsequent process. This is a method for producing a counter electrode that can extremely reduce impurities 9//1 and exhibit stable characteristics over a long period of time without causing side reactions in the VC display body. It provides:

The amount of polytetrafluoroethylene added affects the properties and characteristics of the final plate, but usually
w,,o4゜or W2゜0118 and carbon mixture e/
It is considered to be about 01 to 5 for J1 weight, especially 0.2 to 2
It is preferably used in a range of about 0.05 to 1.0. If the addition amount of polytetrafluoroethylene is too small, the strength as a counter electrode cannot be obtained, and if it is too large, the wettability with respect to the electrolytic solution decreases, making it difficult to withstand practical use. In order to increase the strength when used as a layer, fibers made of phase materials such as silica and alumina, which have almost no effect on the short-temperature chemical properties of the opposite electrode, are used on the receiving side. It is also effective to add it. As another method, as in the case of 911 VC mentioned above, it is also possible to use a method in which the opposite electrode is crimped from both sides to a gold iy+ mesh or an organic material mesh.

In this case as well, the molded product is easily layered by pressure, and no smoldering occurs during the primary process of glumes and pieces.

Examples of the present invention are shown below.

Example I Metal tungsten powder and tungsten dioxide powder were combined with W
After mixing the O and O in a very high ratio and vacuum-sealing them in a quartz tube, heat treatment was performed at 800°C for 10 hours...1.
Attached 0!8 crystals. This old material was pulverized to obtain 11.polar active material, which was mixed with acetylene black in a ratio of 21 g JΔ, and a dispersion solution of fibrillating polytetrafluoroethylene. 1. i ratio f 20% (p
Add 1 L of ethanol, mix and stir (-shi), then roll this, 2
The thickness of the sheet was 0.00 μm.

In this way, a specimen of the opposite 't11 pole material was served] Cm
It was cut into a size of 1x1 scale, and its natural position and position vibration were measured while it was being used for an EC display. Nature.

The position is at -400 mV with respect to Ag/Ag"",
However, when applying a current pulse of 11 nA, IIIE, the potential fluctuation was only a maximum of 10 mV. Moreover, even if it was left in this state for a day and night, the electrode potential of the counter electrode did not change and remained constant. Furthermore, when used as the opposite pole in the EC display body shown in Fig. 1, almost no potential drift was observed, and the 80°
Even after juJ at C11000, it was within ±100 mV.

On the other hand, in the case of using WOI powder as the active material, the potential drift was good, but the potential fluctuation was large and was around 300 mV under the same conditions. Also, γ-Mn
When Oz was used as the active substance, the potential fluctuation was 10 mV or less, but after 240 hours at 80°C, it changed to 1 to 200 mV.

Thus, wzooag was found to be an active material that can exhibit excellent properties as a counter electrode.

Example 2 Gold maple tungsten powder and tungsten dioxide powder were
The mixture was adjusted to a ratio of O and □2, vacuum sealed in a quartz tube, heated at 800°C for 10 hours, and heated to 04
11 crystals were obtained. When this material was used as a powder active material and the same rows as in Example 1 were carried out, the same results were obtained.

Example 3 20 mole% of v205 was added to Wll104Q to prepare active material 1'J↓. . The test specimen was obtained in the same manner as the experiment f/+, +1.
, Ag/Ag”), and other properties are WI
It was almost the same root In as in the case of 8049 alone.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the FXC display. ■・−・Transparent substrate 2...Transparent conductive film 3...EC layer 4...Insulating layer 5... Opposite board 6... old guide board 7...Counter electrode 8... Electrolyte 9...Background material 10... Sealing material

Claims (3)

[Claims] (1) In an electrochromic display using a mixture of conductor powder and electrode active material for the counter electrode, ↑
An electrochromic display characterized by an electrode active material containing w18049 or W2O0418. (2) Lightning, extremely active 9 shoes quality is W18049 or WtoO5
81/'-LixVzOs (0≦x<1). (3) The electrochromic display according to claim &LI or item 8142, wherein the opposing η·, $1i are a mixture of fibrillating fluorinated carbon and an electrode active material.