JPS58147486A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:A guest-host type liquid crystal display element that is made by filling the space between a pair of transparent electrode base plates with a liquid crystal composition containing a yellow pigment represented by a specific formula, using dichromatic pigment with high dichromatic properties and high light fastness, thus showing high contrast and long life. CONSTITUTION:The objective liquid crystal display element is obtained by filling the space between a pair of transparent electrode base plates with a liquid crystal composition containing a yellow pigment of formulaI R is alkyl, aralkyl, cyclohexyl, -CO-R1 (R1 is alkyl, aralkyl, aryl, cyclohexyl) such as a positively anisotropic nematic liquid crystal of formula II (one of R3 and R4 is cyano and the other is alkyl, alkoxy). The yellow pigment is obtained, e.g., by adding 1,2,5,6-tetrahydroxyanthraquinone, potassium carbonate, n-butyl iodide to N,N- dimethylformamide, stirring them at a certain temperature, pouring the reaction mixture into water and recrystallizing the precipitated crystals from acetone.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display element characterized by using a liquid crystal composition containing a dichroic dye.

Currently, there are many products such as calculators and watches that use twisted nematic liquid crystal display elements. However, color displays using color polarizing plates have the disadvantages of dark displays and narrow viewing angles.

In addition, display confectionery that utilizes the guest-host effect by adding dichroic color chips to the liquid crystal ■Does not necessarily require a polarizing plate, so bright reflective color display is possible;■Display color can be changed by selecting the pigment added. It has the characteristics of a wide range of viewing angles and wide viewing angles, and if it is internally illuminated (transmissive type) using a polarizing plate, even higher brightness and higher contrast display is possible. It is a display element that can be adapted to diversity. However, conventional guest-host type liquid crystal display elements
It is impossible to fully satisfy both contrast and luxury.

The reason for this is that conventional dichroic dyes have excellent dichroism and light resistance and do not have these characteristics. As conventional dichroic dyes, azo and anthraquinone dyes are mainly known. Azo type materials generally have a dichroic ratio of 8 to 10 and a light emitting life of several thousand hours, which is generally a high dichroic ratio, but a short emitting life.

-10,000 Anthraquinones generally have a dichroic ratio of 6 to 9 and a photon life of several tens of thousands of hours, but have only a low dichroic ratio.

The Ministry of the Invention and others investigated dyes for display devices that utilize the above-mentioned guest-host effect, and as a result, they discovered a dye with excellent dichroic ratio and light resistance, and completed the present invention.

That is, an object of the present invention is to provide a high-contrast, long-life guest-host type liquid crystal display element using a dichroic dye having excellent dichroism and light resistance.

That is, the present invention provides a liquid crystal display element in which a liquid crystal composition is filled between a pair of transparent electrode substrates at least 10,000 times, wherein the liquid crystal composition is represented by the following general formula (1). , aralkyl 1, cyclohexyl group, -co-R1 group;

In the substituents of R1 and Rg, the alkyl chain and aryl ring may be substituted. ] This is a liquid crystal display element characterized by using a liquid crystal composition containing one or more kinds of yellow pigments.

The dye used in the present invention is generally synthesized as described below. That is, as shown in the reaction formula below, the general formula (I
When the compound represented by I) is treated with an alkylating agent or an acylating agent represented by the general formula (2) in the presence of a deoxidizing agent, a yellow dye represented by the general formula (I) is obtained.

ml) [In the formula, B has the above meaning. X is a halogen atom,
Aryl sulfonic acid ester residue, sulfuric acid ester residue,
Represents an acid anhydride residue. ] Here, the pores of general formula (1) include linear or branched alkyl groups such as methyl group, ethyl group, propyl group, butyl group, amyl group, hexyl group, octyl group, nonyl group, and dodecyl group. , straight chain or branched alkoxyalkyl groups such as methoxypropyl group, ethoxypropyl group, propoxyethyl group, butoxyethyl group, octoxyethyl group, ethoxyethoxyethyl group, p-methoxybenzyl group, P-butylbenzyl group, p-hexylphenethyl group, p-butoxybenzyl &
, P-chlorobenzyl group, aralkyl group such as benzyl group, cyclohexyl group, acetyl group, ethylcarbonyl group, propylcarbonyl group, butylcarbonyl group, pentylcarbonyl group, hexylcarbonyl group, octylcarbonyl group, dodecylcarbonyl group, ethoxymethyl Straight chain or branched alkylcarbonyl M such as carbonyl group, propoxymethylcarbonyl group, aralkylcarbonyl group such as P-methoxybenzylcarbonyl group, p-butylbenzylcarbonyl group, benzylcarbonyl group, p-methylbenzoyl group, p- ethylbenzoyl group,
p-methoxybenzoyl group, p-methylthiobenzoyl group, p-ethoxybenzoyl group, benzoyl group, p-propylbenzoyl group, p-butylbenzoyl group, p-hexylbenzoyl group, p-butoxybenzoyl group, p-
Typical substituents include arylcarbonyl groups such as hexyloxybenzoyl group, p-chlorobenzoyl group, p-phenylbenzoyl group, and cyclohexylcarbonyl group.

Next, the present invention will be explained in more detail using the drawings. @1
The figure is a schematic cross-sectional view showing an example of a transmissive type product display device containing a liquid crystal display element of the present invention, and FIG. 2 is a schematic cross-sectional view of a reflective liquid crystal display element according to another embodiment of the present invention. Section 1.2
In the figure, l is a transparent glass substrate, 2 is a transparent electrode such as indium dioxide provided inside the transparent glass substrate,
8 is a spacer made of Teflon film, for example;
As a result, the cell thickness is set to 10 to 20 μm, 4 is a nematic liquid crystal composition containing a dichroic dye, and 5 is ionization applied to this element, and direct current or alternating current is used. 6 is incident light, 7 is the viewer's eyes, 8 is a polarizing plate, and 9 is a light scattering plate.

In this device, the surface of the transparent electrode is rubbed in one direction with cotton cloth, etc., and the surface is prepared by obliquely vapor-depositing silicon oxide, etc. so that the liquid crystal and dichroic dye are oriented parallel to the surface of the transparent electrode. It is being processed.

The nematic liquid crystal exhibiting positive dielectric anisotropy used in the present invention has the general formula r, where one of Rs and R4 is a cyano group, and the other is an alkyl group, an alkoxy group, or an alkylphenyl group. Represents a phenyl group. ] or a mixture thereof.

Although a transmissive display device is shown in FIG. 1, a reflective display device as shown in FIG. 2 may be used. In this case, a light scattering plate 9 is provided behind the panel.

Although a display device in which color disappears when a voltage is applied has been described above, a display device that exhibits a color when a voltage is applied can be constructed.

That is, a nematic liquid crystal exhibiting negative dielectric anisotropy is used as the liquid crystal, and the surface of the transparent electrode is coated with a surface active material such as N,N-dimethyl-N-octadecyl-8-aminopropyltrimethoxysilyl chloride, dimethyldichlorosilane, or methyltrichlorosilane. A display device can be constructed by aligning the liquid crystal and dichroic dye perpendicularly to the surface of the transparent electrode by treating the liquid crystal with a dichroic dye or by mixing an alignment agent such as cetyltrimethylammonium fluoride into the liquid crystal. .

In addition, if a small amount of cholesteric liquid crystal or chiral nematic liquid crystal is mixed with nematic liquid crystal,
It becomes a display element based on the so-called phase transition type (also called White Tiller type) guest-host effect,
There is no need for a polarizing plate and high contrast can be obtained even with a reflective type.

Next, examples of synthesis of typical dyes used in the present invention will be shown.

Synthesis Example 1 (Compound Todoroki I) 1.2.5.6-thitrahydroxyanthraquinone 2.
7 parts of potassium carbonate, 1.4 parts of potassium carbonate, and 8.7 parts of n-butyl iodide were placed in 20 parts of N,N-dimethylformamide, stirred at 50 to 60°C for 4 hours, and then poured into 200 parts of water. The precipitated crystals are separated from P, washed with water, and dried.

This crude product was recrystallized from amethane to obtain 1.4 parts of a yellow dye having the structural formula F.

m, P, 197-198°C Synthesis Example 2 (Compound 42) 1.2,5.6-tetrahydroxyanthoquinone 2.
In the fu part, 1.4 parts of potassium carbonate was put into 20 parts of N,N-dimethylformamide, and 8.1 parts of P-methylbenzoyl chloride was added at 10 to 20°C, and after stirring at the same temperature for 5 hours, It is poured into 200 parts of water, and the precipitated crystals are separated from P, washed with water, and dried. This crude product was recrystallized from acetone to obtain 1 g (0.9 parts) of a yellow color having the following structural formula.

m-P-286-288°C Synthesis Example 8 In Synthesis Example 1, butyl iodide 8. Flubromide 3.7 parts P-chlorobenzyl bromide 4.
Using 5 parts, the other steps were the same as in Synthesis Example 1 to prepare lower compound 58.
I got ~6.

M8 m, p, 227-282℃ m, 9. 149-158℃ m, p, 245-247u m-P, 264-267℃ The dyes synthesized in this manner are shown below.

ll Mu12 Mu19 Next, the present invention will be explained in more detail with reference to Examples.

Example 1 A liquid crystal cell was treated so that the liquid crystal and the dichroic dye were parallel to the transparent electrode. 17%, 4-cyano-4'-n-pentoxybiphenyl 18%, 4-cyano-4'-n-octoxybiphenyl 17%, 4-cyano-4'-n-pentylterphenyl 10% liquid crystal m 1tla (Es, BDtl C
A liquid crystal composition in which 1% of the above AI dye was dissolved was placed in a container (chemicals).

When a voltage of about 6 volts is applied to the liquid crystal display element, the yellow liquid crystal display changes to almost colorless.

The maximum value of Todoroki's pigment in this liquid crystal display element is 4671
1 m, and the light resistance of this liquid crystal display element was very good.

Example 1 Example 2 A liquid crystal cell treated with vertical alignment or parallel alignment was prepared by adding the cholesteric liquid crystal material cholesteryl chloride 10 A liquid crystal composition in which 1% of the dye was dissolved was injected. In the configuration shown in Figure 2, this liquid crystal display element is colored yellow when no voltage is applied, and becomes colorless when a voltage of 16V or more is applied, producing a bright, high-contrast reflective display even without the use of a polarizing plate. was gotten. In addition to the above-mentioned cholesteryl chloride, the cholesteric liquid crystal material used for the mixed liquid crystal may also be a cholesteryl chloride conductor or a chiral nematic material such as biphenyl or ester.

[Brief explanation of drawings]

Figure 111 is a schematic cross-sectional view of a T-type transmission type liquid crystal display device using a liquid crystal display element according to an embodiment of the present invention, and Figures 11 and 2 are:
FIG. 3 is a schematic cross-sectional view of a reflective liquid crystal display device according to another embodiment of the present invention. In Fig. 1.2, l...glass plate, 2...transparent electrode, 8...spacer, 4...liquid crystal composition, 5...power supply, 6...incident light, 7... - Viewer, 8... polarizing plate, 9... light scattering plate. Figure 1 Figure 2

Claims (1)

[Scope of Claims] A liquid crystal display element comprising a liquid crystal composition filled between a pair of transparent electrode substrates, wherein the liquid crystal composition contains one yellow dye represented by the following general formula (I). Or a liquid crystal display element characterized by using a liquid crystal composition containing two or more types. [In the formula, R represents an alkyl group, an aralkyl group, a cyclohexyl group, or a -CO-R1 group, and the group represents an alkyl group, an aralkyl group, an aryl group, or a cyclohexyl group. t'1. In the substituents of kL2, the alkyl chain and aryl ring are II! It may be converted to f. ]