JPH03179427A - Electrochromic display element - Google Patents

Abstract

PURPOSE:To obtain an electrochromic display element having a clear display color and a long service life by incorporating a specified polyimide deriv. CONSTITUTION:A polyimide deriv. based on repeating units represented by formula I (where R is an organosilicon compd.) is incorporated. The repeating units of polyimide represented by the formula I are obtd. by imidating a tetracarboxylic acid component with a diamine component represented by a formula NH2-R-NH3. An electrochromic display element having a clear display color and a long service life is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrochromic display element (hereinafter referred to as ECD) using a polyimide derivative.

(Prior art) Conventionally, electrochromic substances (hereinafter referred to as E
Examples of the C substance include inorganic transition metal oxides such as tungsten oxide, and organic compounds such as viologen derivatives and quinone compounds. Although ECDs using inorganic EC materials generally have an excellent driving life, they have the drawbacks of a limited number of display colors and dark color tones.

On the other hand, organic ECDs generally display a wide variety of colors, are clear, and have a large extinction coefficient. Furthermore, compared to metal oxides, it has the advantage of being easier to produce large-area ECDs at a lower cost, having good processability, and being able to be coated. However, since organic EC substances are colored by radicals, side reactions are likely to occur and reversibility may be poor. In order to overcome this drawback, several methods such as polymerization have recently been investigated.

(Problems to be Solved by the Invention) Among EC materials for ECD, a compound that exhibits stable reversibility, provides clear display colors, and has an excellent driving life has not yet been found. Therefore, it is desired to develop an ECD using an EC material with clear display colors and an excellent driving life.

(Means for Solving the Problems) The present invention provides an ECD using an EC material that displays clear colors and has an excellent driving life.

That is, the present invention relates to the general formula (I) [wherein R represents an organosilicon compound]. ] This is an ECD characterized by containing a polyimide derivative whose main component is a repeating unit represented by the following.

Next, the polyimide derivative used in the present invention will be explained in detail. The repeating unit of the polyimide represented by general formula (1) consists of a tetracarboxylic acid component and NH, -R-NH
, (R is the same as above). Examples of this diamine include those shown below.

In addition, Compound No. is the same in Examples as well. used for.

Compound no.

Structural formula % Formula % ) The raw material tetracarboxylic acid compound constituting the repeating unit represented by the general formula (J) includes, for example, pyromellitic dianhydride, 3,3'', 4,4'-biphenyltetracarboxylic acid dianhydride, 2,3.3',4'biphenyltetracarboxylic dianhydride, 3.3',4゜4'-benzophenonetetracarboxylic dianhydride, 4.4'-oxycyphthalic dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylsulfone dianhydride,
2.2'-bis(3,4-dicarboxyphenyl)
Hexafluorobrobannihydride, cyclopentanetetracarboxylic dianhydride, 2.3.5-1-lycarboxycyclopentyl acetic dianhydride, 5-(2,,5-dioxotetrahydro-3-furanyl)- Examples include 3-cyclohexene-1,2-dicarboxylic anhydride.

A polyimide containing a repeating unit represented by the general formula (1) is dehydrated and ring-closed to form a polyamic acid containing a repeating unit represented by a tetracarboxylic acid component and a diamine component (in the formula, R represents an organosilicon compound). . Generally, polymerization is carried out in an organic polar solvent under anhydrous conditions at a temperature of 80° C. or lower, preferably 50° C. or lower, to form a polyamic acid solution. Examples of organic polar solvents include N, N
-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, diglyme, cresol, halogenated phenol,
N-butyl cellosolve and the like are preferred. Particularly preferred is N,N-dimethylacetamide. These organic polar solvents may be used alone or in combination of two or more without any problem.

The polyamic acid solution obtained as described above was
Polyimide is obtained by dehydrating and ring-closing at a temperature of 0°C, preferably 150 to 250°C, and simultaneously volatilizing the organic solvent.

The ECD in the present invention will be explained below based on the drawings. A typical ECD is one in which an EC substance and a supporting electrolyte are dissolved in a solvent to form a solution, which is sealed in an ECD cell as shown in FIGS. 1 and 2, for example. In Figures 1 and 2, (1) is a transparent substrate and (2) is a transparent electrode. Usually, transparent conductive glass or the like is used in which the transparent substrate (1) and the transparent electrode (2) are integrated. . (3) is a spacer, which is usually made of polyester, polyimide, Teflon, etc. The electrode spacing is 0. The size is 01 x 1 mm, and a background body may be inserted between the electrodes. The background body uses a porous white plate made of ceramics or the like.

A solution (4) containing an EC substance and a supporting electrolyte is sealed in the ECD cell configured as described above to obtain an ECD. Since it is easy to form a film with polyimide, as shown in Figure 2, a polyimide film is coated on a transparent electrode (2) to provide a polyimide film, and a solution containing a supporting electrolyte (6) is applied.
may be included.

The method for forming the polyimide film will be explained below.

The polyamic acid is prepared as a 0.1 to 50% by weight solution, preferably a 1 to 20% by weight solution, in an organic solvent and applied onto a transparent electrode by a dip method, a spinner method, a spray method, a printing method, or the like. After coating, heat treatment is performed at 100 to 400°C, preferably 150 to 250°C to dehydrate and ring-close the polyamic acid to obtain a polyimide coating. At this time, a supporting electrolyte may be mixed into the polyamic acid solution.

Next, the supporting electrolyte used in the ECD of the present invention will be explained. As the supporting electrolyte, one or more salts soluble in the solvent used, such as tetraethylammonium bromide, tetrabutylammonium iodide, tetrabutylammonium perchlorate, and tetrafluoroborate, are used. In addition, as a solvent, an aprotic polar solvent such as N,N-dimethylformamide,
One or more types of N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, acetonitrile, propylene carbonate, γ-butyrolactone, 1,2-dichloroethane, dichloronaphthalene, etc. are used. The concentration of the supporting electrolyte ranges from 0.01 to 1 mol/mole/mole depending on the solvent used, the characteristics of the supporting electrolyte, and the required display characteristics.
It can be selected within a range of about L. This solution is sealed in a cell as shown in FIG. 1 or 2 to form the ECD of the present invention.

When a lead wire is taken out from the electrode of this ECD, connected to a power source or a circuit, and a voltage is applied, coloring can be obtained.

The ECD of the present invention is characterized by clear display colors and excellent driving life.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these, but
The parts shown in the examples are parts by weight.

Example I To 100 parts of N,N-dimethylacetamide, compound No.
12.4 parts of diamine of 1 was dissolved, and in a nitrogen atmosphere, 1,
4,5.8-Naphthalenetetracarboxylic dianhydride 13
．． Add 4 parts (almost equimolar to the diamine) and heat at 20-30°C.
The mixture was allowed to react for 24 hours. The resulting polyamic acid solution was coated on ITO transparent glass mI! using a spin coater. j!
applied on top. After coating, it was heated at 200° C. for 1 hour to cause dehydration and ring closure, thereby forming a polyimide film. This film was used to encapsulate a 0.05 mol/flood propylene carbonate solution of tetrabutylammonium iodide to obtain an ECD.

Next fl! Approximately 1 when voltage is applied between the poles from a DC power supply
．． A bright brown coloring was obtained at 8V. When the voltage application was stopped, the color disappeared and returned to colorless. This was repeated to measure the driving life. The driving life was 10' or more.

Examples 2 to 3 A polyamic acid solution was obtained in the same manner as in Example 1 using cyan □ shown in Table 1 instead of the diamine of Compound No. 1, and then an ECD was prepared.

Next, coloring and fading and driving life were measured, and the results shown in Table 1 were obtained. Note that the shear n of compound No. 8 used in Example 3 is 4.

Table 1 Example 4 In Example 1, 20% of the tetracarboxylic acid component was added to 3.
A polyamic acid solution was obtained in the same manner as in Example 1 except that 3',4,4'-biphenyltetracarboxylic dianhydride was used, and then ECD was prepared. Next, coloring and fading and driving life were measured, and the results shown in Table 1 were obtained.

Comparative Example 1 1,1'-diheptyl-4,4°-bipyridinium tribromide was dissolved in water at a concentration of 0.01 mol/Q, and potassium bromide was dissolved as a supporting electrolyte at a concentration of 0.2 mol/Q. ECD was obtained for the obtained solution in the same manner as in Example 1, and voltage was applied. Color it purple at about 2V, reverse the polarity and add about -1.5V.
The color was quickly erased with V and became colorless. When this was repeated and the driving life was measured, the driving life was about 101 times.

As is clear from the comparative examples, the ECD of the present invention containing the polyimide derivative represented by the general formula (I) has a longer driving life than the ECD using a known viologen compound.

(Effects of the Invention) The present invention provides an EC with clear display colors and excellent drive life.
D was obtained.

[Brief explanation of drawings]

1 and 2 are schematic cross-sectional views of the ECD. Transparent substrate 2...Transparent electrode spacer Solution containing EC substance and supporting electrolyte polyimide coating Solutions containing supporting electrolytes

Claims (1)

[Claims] 1. The following general formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) [In the formula, R represents an organosilicon compound. ] An electrochromic display element characterized by containing a polyimide derivative whose main component is a repeating unit represented by the following.