JPS5842684A - Display element - Google Patents

Abstract

PURPOSE:A display element with good contrast and excellent light resistance, prepd. by enclosing a liquid crystal contg. a specified anthraquinone-base multi- color dyestuff in a cell formed by oppositely placing two transparent plate electrodes. CONSTITUTION:After 1-amino-4-nitroanthraquinone-2-carboxylic acid of formula Iis converted to the corresponding acid chloride by the action of phosphorus pentachloride, thionyl chloride, etc., the acid chloride is condensed with an aniline deriv. of formula II (wherein R is 1-8C straight or branched-chain alkyl; x is 1-5) followed by reducing a nitro group to obtain an anthraquinone- base multi-color dyestuff of formula III. Then a nematic or cholesteric liquid crystal with positive or negative dielectric anisotropy contg. said multi-color dyestuff is enclosed in a cell with an orientated inner surface formed by oppositely placing nearly in parallel two plate electrodes of which at least one is transparent across a periphery-sealing material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display element using a guest-host type liquid crystal7. The present invention relates to a display element containing an anthraquinone pleochroic dye represented by 1 to 8 linear or branched alkyl groups in a liquid crystal.

A method of displaying by sandwiching a nematic or cholesteric liquid crystal containing a pleochroic dye and having positive or negative anisotropy between two electrodes and applying a voltage is already known as a guest-host display element. It is being

The characteristics of this display element are that it has traditionally been used in calculators.

Compared to twisted nematic (TN) confectionery used in watches and the like, (1) the viewing range of the display is wider;

(2) The degree of freedom in selecting hue is large.

(8) The number of polarizing plates used is reduced.

Therefore, there are advantages such as cost reduction. - However, since this method displays by changing the molecular alignment direction of the pleochroic dye and changing the absorption of light in the liquid crystal layer, the following should be considered for the dye material used. Items are required to be met. That is, (1) it can be dissolved in the host liquid crystal to obtain a practical coloring density;

(20 Good dichroism that contributes to display contrast.

(8) Excellent in various durability including light resistance.

etc. can be opened.

As a result of various studies on display elements using pleochroic dyes that can be used in guest-host elements from this viewpoint, the present invention has been made based on the results of various studies on display elements using pleochroic dyes that can be used in guest-host elements.
The results showed that a device using a dye in which a group represented by general 2R (OC*HJn O+) was bonded to the 2-position of an anthraquinone compound via a carbamide bond was practically useful.

That is, in the present invention, two electrode substrates, at least one of which is transparent, are placed substantially parallel to each other to form a cell with a peripheral sealing material interposed therebetween, and a liquid crystal is sealed in the cell to form a display element. The present invention is a display element characterized by using a liquid crystal containing at least one polarity of an anthraquinone pleochroic dye represented by the general formula (1).

The device according to the present invention has a cell that is oriented on the surfaces of two electrode substrates so that the long axes of liquid crystal and dye molecules are approximately parallel to the substrate surfaces and aligned in a certain direction, and the dielectric anisotropy is positive. A display element containing a nematic liquid crystal and arranged so that the light transmission axis (polarization axis) of one polarizer provided outside coincides with the alignment direction of the surface of the adjacent electrode substrate; A display element in which a nematic liquid crystal with negative dielectric anisotropy is filled in a cell whose electrode substrate surface is aligned so that the long axes of liquid crystal and dye molecules are aligned almost perpendicularly, or a display element with positive dielectric anisotropy. A liquid crystal composition in which a cholesteric liquid crystal or an optically active substance is added to a nematic liquid crystal to give the liquid crystal an arm structure.Both electrode substrate surfaces are both horizontally aligned, both are vertically aligned, or one is horizontally aligned. , and display elements sealed in vertically oriented cells, etc., and their range of applications is extremely wide. In realizing these display elements, there are the following methods for imparting orientation to liquid crystals and dye molecules.

The vertical alignment treatment may be carried out by a known treatment method in which the surface of the electrode substrate is treated with a silane coupling agent containing a long-chain alkyl or fluoro group, quaternary η ammonium, pyridinium salt, lecithin, a surfactant, or the like. Further, as the horizontal alignment treatment method, a rubbing method in which the electrode substrate or its organic or inorganic overcoat material is rubbed in a certain direction with a cloth or the like, or a method such as oblique evaporation of silica or the like may be used.

The electrode substrate subjected to the orientation treatment in this way was #1i
are opposed to each other in parallel to form a cell through a peripheral sealing material such as epoxy resin or glass frit. At this time, a spacer, a transfer, etc. may be formed within the cell or within the surrounding sealing material.

After forming the cell in this manner, liquid crystal is injected through the injection port, and the injection port is sealed with epoxy resin, solder, or the like, thereby forming a liquid crystal display element.

In addition, during these manufacturing processes, the inside of the cell is divided into two parts, and different liquid crystals are injected into each part, and multilayer electrodes, barriers,
A reflective layer or the like may be formed.

1-Amino-4-nitroanthraquinone-
After converting 2-carboxylic acid into acid chloride by reacting with phosphorus pentachloride, thionyl chloride, etc., the following general 200 million) HIN-@)
-〇(C2H1o■R(3) [wherein n and R are formula (I)
It is synthesized by condensing an aniline derivative represented by the following formula and then reducing the nitro group. Further, if necessary, it can be purified by recrystallization or column chromatography.

[Synthesis Example 1] 15 L5 parts of amino-4-nitroanthraquinone-2-carboxylic acid, 2 parts of thionyl chloride, and 5 parts of pyridine α are added to 50 parts of nitrobenzene, and the temperature is raised to 90°C.

After raising the temperature and reacting at 90 to 95°C for 6 hours, the mixture is cooled to room temperature, filtered, and washed with a small amount of nitrobenzene. Obtained 1-
Amino-4-nitroanthraquinone-2-carboxylic acid chloride was mixed with monochlorobenzene 2 containing 6 parts of P-(2-(2-ethoxyethoxy)ethoxy)aniline 1a.
00 parts at room temperature.

After reacting at room temperature for 2 hours, filter and wash with methanol.

Wash with water. The obtained wet cake of carboxamide was added to 240 parts of water, 2 parts of n-butanol, 1 part and 4 parts of sodium sulfide (purity 467%) were added, and the temperature was raised to 90°C. After raising the temperature, the reaction was carried out at 90 to 95°C for 5 hours.
When heated at ℃ and washed with hot water, 185 parts of the target dye (melting point 164
-1645°C).

The acetate/dissolution color of this dye is blue.

λmax 605 nm (in acetone) [Synthesis Example 2
] Dye 2 In Synthesis Example 1, when 12.6 parts of P-(2-butoxyethoxy)aniline was used as a base for P-(2-(2-ethoxyethoxy)ethoxy)aniline, the target dye was 1:8 parts ( (melting point 161-162°C).

The acetate/dissolution color of this dye is blue.

λm, ax 605 nm (in acetone) Other pleochroic dyes used in the present invention can be similarly synthesized by using various aniline derivatives represented by the above general formula @). Table 1 lists the structures and acetone-soluble colors of typical pleochroic dyes.

The pleochroic dye used in the present invention has excellent solubility in liquid crystals, and when used in the liquid crystal display element of the present invention, deep coloring can be obtained and the dichroic ratio is large, so that it has good contrast. It is possible to do this.

Among them, n is 1 to 5. It is preferable that R is an alkyl group having 1 to 8 carbon atoms because the solubility of the pleochroic dye in the liquid crystal is high. Table 2 shows the properties of the dye compound obtained when it was dissolved in nematic liquid crystal E-8 manufactured by Merck & Co., Ltd.

<Table 2> (λmax indicates the maximum absorption peak wavelength in the visible light region) Next, examples of display elements according to the present invention will be shown.

A liquid crystal composition was prepared by adding 1 amount of a dye to a cholesteric liquid crystal with positive dielectric anisotropy, which was obtained by adding 28 weight: It% of cholesterol nonanoate to Merck's nematic liquid crystal.
The surfaces of the two electrodes were both aligned in a fixed direction and horizontally by a rubbing method, and when they were sealed in a cell arranged with a gap of about 8 μm and an AC voltage of 45 V was applied,
The maximum absorption wavelength in the visible light region was 585 to 600 nmK, and the color changed from dark blue to almost colorless, and a good display appearance was obtained. In this example, instead of 10 dyes, 2 to 10 dyes
When a display element was made in the same manner using , the display appearance changed from deep blue to almost colorless, resulting in a good display appearance.

Furthermore, an ultraviolet light cut filter of 880 nm or less was placed in front of this display element, and a white scattering plate was placed behind it, and the display remained colored even after being irradiated with light for more than 1,000 hours in an ultraviolet phatometer.

There was no change in display characteristics.

In the above embodiments, only cholesteric liquid crystals are shown, but it is clear that it is also useful when only nematic liquid crystals are used. Furthermore, it is also possible to perform black and white display by coexisting pleochroic dyes exhibiting yellow and reddish-purple colors.

Furthermore, in this example, as a nematic composition with positive dielectric anisotropy, E-
8 was used, but as can be seen from the above explanation, it is limited to a particular composition, and the effect will not change even if it is a ship type, phenylcyclohexane type, ester type, pyrimidine type, or a mixture of these. do not have.

The example shown here is the basic configuration of the present invention, including providing two liquid crystal layers, providing a light source, a filter, a reflective film,
A light guide, a scattering plate, etc. may be provided, and either analog display or digital display can be used.

As shown above, the element according to the present invention is a display element that has good contrast, can obtain sufficient coloring density, and has good light resistance, which is a display element that has excellent characteristics in terms of practical use.
It can be used alone or in combination with other materials for a variety of applications, and can be used in transmission type, 9 reflective type, calculators, 2 clocks, various measuring instruments, game machines, displays for vehicles, and cameras.

It can be applied as a display device for audio and other home FIL products.

Claims (1)

[Claims] Two electrode substrates, at least one of which is transparent, are placed parallel to each other by t' with a peripheral sealing material in between to form a cell, and liquid crystal is sealed to form a display element. , the following general formula (
1,) At least one anthraquinone pleochroic dye represented by [wherein n represents an integer of 1 to 5, and R represents a linear or branched alkyl group having 1 to 8 carbon atoms] A display element characterized by using a liquid crystal containing the above.