JPS5945430A - Electrochromic display element - Google Patents

Abstract

PURPOSE:To form an element having excellent responsiveness and is free from deterioration with age in an electrochromic (EC) display element using a liquid electrolyte, by using the liquid electrolyte in the solidified state in which the electrolyte is absorbed in a specific cross-linked type polymer. CONSTITUTION:A solidified electrolyte obtd. by adsorbing a liquid electrolyte on a cross-linked polymer obtd. by cross-linking PVA with a dicarboxylic acid (anhydride) (preferably the polymer crosslinked by using about >=2wt% pyromellitic anhydride) is used. The above-mentioned solidified electrolyte 4 is sandwiched between an upper glass substrate 1 provided with a transparent conductive film 2 of tin oxide, etc. and EC electrodes 3 consisting of a thin film of Prussian blue, etc., and a lower glass substrate 7 provided with a counter electrode 6 of Cr-Au, etc., whereby the EC display element is formed (a symbol 5 is a spacer).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrolyte for an electrochromic display element, and more specifically, it solidifies the electrolyte,
It is concerned with improving the overall performance of the device.

In engineering comic book display elements, an electrolyte and in many cases an electrolyte solution was used. However, when a solution is used, there are problems with air bubbles when the solution is injected and the panel breaking at high temperatures due to the difference in expansion coefficient between the display cell and the solution.

Therefore, it has been considered to use a solid material as an electrolyte, and oxide thin films such as quartz dioxide thin films and mental oxide thin films have been used as ion conductors for protons. However, Toran et al.'s solid-state electrical material had the drawback of high resistance. At 7''C, the response of the element becomes slow and the voltage increases (t%).Furthermore, with the solid electrolyte of Kosai et al.
The question arose as to whether there was sufficient contact between the tilectrochromic electrode and the electrolyte, or between the counter electrode and the electrolyte. That is, when contacting with a liquid, a satisfactory contact can be expected due to the fluidity of the liquid, but when solids come into contact with each other, a phenomenon of peeling may occur. In particular, mark the voltage 7JOL
, r: If the driving state continues for a long time, it may become a major instability factor.

In order to eliminate these drawbacks of solid 731M quality, electric
r, JR solution A method of solidifying the gold by including it in the gold polymer was considered. In Jin's method, the contact with the electrode is close to the liquid and the Tl! It is believed that if the amount of electrolyte solution is sufficiently large, the conductivity will be close to that of a liquid, so it is thought that the above-mentioned drawbacks of the solid electrolyte can be eliminated and the electrolyte can be solidified. The present invention provides a specific structure for an electrolyte having a structure in which an electrolytic solution is supported on a polymer, and is particularly applicable to a solution using water as a solvent.
The aim is to find a polymer that has 411.

To do this, we will first find a water-soluble 1″ TI molecule and then crosslink it to make it insolubilized.

When considering polyvinyl alcohol, polyvinyl alcohol is a typical water-soluble polymer.However, this 1. alone is water-soluble and cannot make liquids compatible.It is not possible to crosslink this. I can do it
If it is, it is possible to support it without dissolving it in a liquid. Therefore, in order to crosslink this, the esterification reaction is applied as follows: ○II OH OOH --O ■ C=0 -aH, -0IT-OH! -0H- fJII, the OH group of the alcohol moiety undergoes a total esterification reaction of the carboxylic acid group to form a bond. If this operation sound spans two polymer chains, it should be possible to crosslink the polymers. Therefore, the crosslinking agent is a dicarboxylic acid. However, in this case, it is clear that an acid anhydride may be used instead of the dicarboxylic acid.

Additionally, crosslinked polymers generally do not dissolve in solvents due to their polymer structure, and are therefore difficult to mold. Therefore, it would be desirable if n1■ to be crosslinked could be dissolved in a liquid, formed into a film, and then crosslinked into a polymer. For this purpose, a desirable method is to first mix the polymer and crosslinking agent and dissolve them in a working solution, then pour the mixture onto a glass substrate or the like and dry it to form a film and then crosslink it.

The present invention will now be described in detail with reference to Examples.

Example 1 Pyromellitic anhydride is used as a crosslinking agent. Polyvinyl alcohol was dissolved in water at a concentration of 10% (by weight), and pyromellitic anhydride was added at concentrations of 2%, 4%, 6'A, 8%, and 10% based on the total polyvinyl alcohol. Since pyromellitic anhydride does not dissolve in water at room temperature, it will dissolve when the solution is heated to about 80℃. In this way, pour the CC adjustment solution onto a glass plate and heat it on a hot plate at about 80℃. The film is then evaporated and dried.Then, a bright film is formed, and there is no crystallization of the non-fobilometic acid, and the nI7 is formed. Allow the crosslinking reaction to occur.Then, the reaction time was increased to 1 hour, 20S, 3 hours, 4 hours, and 5 hours, and the resulting coating and film absorbed water. The results are shown in Figure 1 and are 7. It can be seen that more than 1% of the crosslinking agent is required to make the material insolubilized. Agent 'M' 4th, reaction time 4 hours, before absorption by water-absorbing polymer σ) about 3.5 times I
ll;) It can be seen that it has heavy M. This is I and 11y
This shows that the amount of water contained in the material is approximately 2.5 times that of the polymer.

The electrolyte is absorbed into the polymer obtained as described above, and the solidified electrolyte is formed. The above-mentioned crosslinking issue is about the crosslinking polymer with 4 parts of crosslinking agent and 4 hours of reaction time.
Soak it in f-IM potassium chloride solution! A solidified electrolyte was made by completely absorbing it.

Component f: It was incorporated into a display panel with a structure as shown in Figure 2. Here, 1 is an upper substrate glass, and 2 is a transparent conductive film made of tin oxide. 3 is Electrochromic'FJjL l
In this case, Prussian blue was used. This Prussian Blue Thin BCA contains Felicyan Potassium Ka
[F(B (aN)a ] and ferric chloride FeO
By electrolytic reduction over tin oxide in a mixed solution of '? I! A film was formed by depositing it on top.

4 is the above-mentioned solidified electrolyte, 5 is a glass substrate, 6 is
is the lower glass plate. The display 1 pole of this display cell has a metal engraving I~ as shown in FIG. 3, and can be switched by moving the display from right to left or from left to right. Still 7&J, Cr-A? The vaporized shoulder membrane of No. 4 is used as a counter electrode.

In such a display device, first, the newly formed Prussian blue film is colored in the evening, so it is connected to the gold of one of the two display films on the opposite electrode, and the color disappears.The display electrode is The area is←
Since only 6 mc/tm'' is added as the display charge amount, the charge m required for erasing the color is 2.40 pc.
/cm'. Therefore, the gold electrode-display wheel (IQ in the amount of electricity)
A constant current of pA was applied for 24 seconds to decolorize the sample. Next, between the film that remains mottled and this colorless film (1,
7V electric power, 7 colors 1 voltage becomes low voltage t4]1. Then, the blue display shifted from right to left. The response at this time was 58ec. There was a liquid on the moon. 9: Considering that 1 cup takes 2 seconds, it can be seen that the time is considerably slowed down due to gelation.

Example 2 Implementation (!□Same display device as in 111: ('i ri z) The same crosslinking conditions were used, but this time, film forming and I
"I added an electrolyte to the solution, i.e. 1M
Polyvinyl alcohol was dissolved in an aqueous solution of potassium chloride at a ratio of 10 parts by weight, and 11 parts of anhydrous pyromellit was mixed into this solution at a ratio of 4 parts by weight to polyvinyl alcohol. Kotff: 120℃
A film of 41J vinyl alcohol was made by crosslinking for 4 hours.Water was absorbed into this film and used as an electrolyte.This was incorporated into a display device of the same type as in Example 1. Coloring/decoloring was switched.As a result, the response time for coloring/decoloring was 4 seconds, which was faster than in Example 1.

Example 3 A display device was fabricated in which a Prussian blue electrode was electrolytically deposited on the gold electrode 7 in FIG. 2 of Example 1, so that it could be driven between the gold electrode 7 and the display electrode. In this case,
Since the counter electrode is blue, it is difficult to see the display switching clearly. Therefore, when crosslinking polyvinyl alcohol with gold, we decided to disperse titanium oxide for crosslinking. In other words, after dissolving in polyvinyl alcohol fl M potassium chloride solution at a ratio of IDwt%, titanium oxide powder is ground into fine particles with a milk pestle.
Make it 'r'. Add anhydrous pyromellit Q3 t to this liquid,
Rinse the polyvinyl alcohol so that it becomes 4Wf and φ. After that, it was cross-linked at 120°C for 4 hours. σ) Water is absorbed into cross-linked polyvinyl alcohol to form an electrolyte, and this is incorporated into a display device.A7.

The pressure between the display electrode and the counter electrode of this display device is 097v
When voltage was applied to the display electrode at a low voltage (11+1), the color of the display electrode disappeared and a white background appeared due to the titanium oxide in the electrolyte.The response at this time was the same as that of the liquid. 2 sec.The response was slower than in Example 1.2 because the distance 1tlff through which the current flowed was shorter.In other words, in Tacho Example 1.2, the current was However, in Example 3, there is a flow between the display electrode and the counter electrode, and the cell thickness is thinner.
The thinner the electric MJPt, the lower the resistance and the faster the response.

As can be seen from Examples 1 and 2.3, although the conductivity of crosslinked polyvinyl alcohol is lower than that of an aqueous solution, it is sufficiently conductive to a cell of 11%, and a response comparable to that of an aqueous solution can be obtained. This is because in addition to the resistance of the electrolyte, there is the interfacial resistance of the membrane, and this interfacial resistance is the cell's 11. The electrolyte resistance is constant regardless of J, but the thinner the electrolyte is, the lower it is, and if the cell is sufficiently thin, it will hardly affect the response.

Example 4 As the dicarboxylic acid to be cross-linked, we will try to use malignant acid. 1 of polyvinyl alcohol as in Example 1. 11) An aqueous solution of kfF was added to this so that maleic acid was at a ratio of tOWC to polyvinyl alcohol, and a crosslinking reaction was carried out at a temperature of 130° C. for 1 hour. When the resulting crosslinked polyvinyl alcohol film was allowed to absorb the electrolyte liquid, the 1a3 molecule film did not maintain its original shape and became thin, resembling Jn agar. That is, it absorbed water in a solidified state but without a clear shape. This water-absorbing polymer was also used in Example 1.
It was incorporated into a similar display device. Even with this, the bubble problem could be resolved. Also regarding this display device, Example 1
Using the same driving method as above, it was possible to move the entire color charge to the right and left, and the response at that time was 288C, the same as the liquid.

Example 5 Maleic acid was used in the same manner, but the crosslinking conditions were changed to a temperature of 130°C.
After 4 hours, the maleic acid was added to the polyvinyl alcohol by 1'CjW t %. As a result, a semi-solid substance was obtained in the same state as in Example 4, and when the electrolyte was absorbed into this substance, C1: The same substance as in Example 4 was obtained.

From Examples 4 and 5, it can be seen that when maleic acid is used, it cannot be formed into a film. The reason for this is the reaction (lt 0
) I think this is due to the difference. This is because acid anhydrides are more reactive and react under milder conditions.

Example 6 Crosslinking was carried out in the same manner as in Example 6 using adipic acid. Even in this case, no film was formed under the conditions of 4Wtq4 at 130°C for 4 hours. However, the bubble problem could be solved.

Example 7 Crosslinking was carried out in the same manner and under the same conditions as in Example 2, this time using maleic anhydride. In this case, crosslinking could be achieved in the form of a film. This film was incorporated into the same display device as shown in FIG. 2, and colored charges were transferred to the right and left sides in the same manner as in Example 2, and a burnout response of 1.4 and q e c was obtained.

Example 8 The same crosslinking agent as in example j was used, but this time polyvinyl alcohol f 177 instead of 1 p
Dissolved in an aqueous solution of lithium perchlorate. Then, an electrolyte was prepared by absorbing water into cross-linked polyvinyl alcohol made from this solution (cross-linking conditions were the same as in Example 2).This electrolysis 'R was then placed in a display device similar to that shown in Fig. 2. In this example, tungsten oxide (not Prussian blue) was used as the electrochromic material.Tungsten oxide was used and one was machined into a vacuum steamed eyebrow.

In the case of tungsten oxide, Q1 is
It is colorless. 240 at Ln7 current between this pole and all counter electrodes.
A charge of pc was injected to transfer the colored charge between the two membranes. However, the voltage was 1.5V. As a result, the response was 2 seconds, which was slower than the response Q when using a liquid, which was 5 seconds.

Example 9 Similar to Example 3, butane oxide powder was mixed during film forming in all Examples 8 as well. Then, as in Example 3, it was driven with a counter electrode. This time, all striped counter electrodes were left as they were, and the voltage was set at ±1°2■. As a result, the response was 0.5 sec, which was the same value as the liquid.

2. As explained and clarified with reference to Examples, the present invention has 1
It is clear that 2T can be used for any electrochromic display using an aqueous solution, and if the cell is made sufficiently thin, the response can be made comparable to that of a liquid. It is also clear that the present invention can solve all problems in one bubble.

[Brief explanation of the drawing]

a'51 Figure Q311, tsu, 111; When water pyromellitic acid is used as a crosslinking agent σ) Change in water absorption of crosslinked polymer depending on reaction time and type of crosslinking agent. Figure 2 shows the structure of the electronic display device used in the examples.
l+glass, 2 (rj: Imiaki7.F7den11';
's 3 is an electrochromic membrane, 4 is a solidified electrolyte according to the present invention, 5 is a space →], 6 is a lower Ill glass, and 7 is an ar-A thin film. 3rd i! 2Ir15 is the display pattern of the display device. μ-hi Applicant Daini 1I9 Co., Ltd. Joint Agent Patent Attorney Tsutomu Mogami

Claims (1)

[Claims] (1) At least two electrodes and 't'f Il'/g
In the electrolyte, polyvinyl alcohol is cross-linked with dicarboxylic acid or carboxylic acid anhydride, and the electrolyte is formed into a water bath and absorbed by a polymer having a risk of fr: characterized by an electrochromic coating. Selected from acid, maleic anhydride
An electrochromic display element whose characteristic is '1'. <3) An electrochromic display element characterized in that L1 pyromellitic anhydride is contained in a ratio of -1r to polyvinyl alcohol at a ratio of 21 or more. .