JPS61148291A - Compositoin for liquid crystal color display - Google Patents

Abstract

PURPOSE:To obtain the titled composition having high coloring power, dichroic ratio, contrast and compatibility, and excellent stability and durability, by dissolving a specific anthraquinone-type dichroic blue dye in a nematic liquid crystal having positive dielectric anisotropy. CONSTITUTION:The objective composition can be prodoced by dissolving one or more anthraquinone dye of formula [R is (cyclo)alkyl or phenyl; X is -O- or -NH-] (e.g. 1,4-diamino-N-methyl-2-anthraquinonylcarboxamide) in a nematic liquid crystal having positive dielectric anisotropy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition for liquid crystal color display that utilizes electro-optic effects, which comprises a liquid crystal composition and a dichroic dye.

More specifically, the formula (I) (in formula (I), R is an alkyl group or a phenyl group which may be cyclic, X
The present invention relates to a liquid crystal color display composition in which at least one anthraquinone dye represented by 10-group or -NH- group is dissolved and included in a nematic liquid crystal having positive dielectric anisotropy.

It is well known that liquid crystal compositions containing dichroic dyes are used for "guest-host" display devices in the field of liquid crystal technology, and are attracting attention as display devices for watches, calculators, televisions, etc. There is.

These display devices utilize the fact that the absorption spectrum of dichroic dyes strongly depends on the angle between the long axis of the dye molecule and the vibration direction of incident polarized light. In other words, by dissolving a dichroic guest dye into a host liquid crystal with a fixed alignment, and controlling the alignment of the liquid crystal with an electric field, the alignment of the dye can also be controlled at the same time.
This method utilizes the change in color density at this time.

In order to create and operate electro-optical devices using nematic liquid crystals, the liquid crystals must have a molecular orientation structure that is controlled in the direction of the applied electric field. In general, liquid crystal molecules tend to have rod-like molecules, and the orientation structure of the molecules is as follows.

If the long molecular axis of the liquid crystal is perpendicular to the container wall, this structure is called homeotropic.

Furthermore, when the long axis of the liquid crystal molecules is square to the container wall, it is called homogeneous. Also 2
If the alignment lines of the two homogeneous alignment walls are at right angles, a twisted nematic liquid crystal structure is obtained.

Many nematic liquid crystals can be converted to a cholesteric phase by adding certain optically active substances or cholesteric liquid crystal compounds. In this case it is the helical axis of the cholesteric phase that is homeotropically or homogeneously oriented. The thus converted cholesteric liquid crystal material undergoes a phase change upon application of an electric field and becomes a nematic state.

In this way, the guest-host system currently has two methods: using nematic liquid crystals with positive or negative dielectric anisotropy, and adding optically active substances to these liquid crystals to change them from a cholesteric phase to a nematic phase by applying an electric field. There is a method of using a phase-transition type liquid crystal that undergoes a phase transition.

Among these methods, the composition of the present invention can be used in a method that uses a nematic liquid crystal with positive dielectric anisotropy or a nematic liquid crystal that has been converted into a phase transition type by adding an optically active substance or the like to the nematic liquid crystal. This is a composition for liquid crystal color display.

In general, dichroic dyes used in liquid crystal color display devices that apply this principle have 1°, sufficient coloring ability in a small amount, 2°, large dichroic ratio, and voltage application. - Kokichi, which shows a large contrast when no voltage is applied, 3°, has sufficient compatibility with liquid crystal, 4°
The basic requirements are that the device has excellent durability, is stable, and does not deteriorate the performance of the device even after long periods of use.

The present invention is based on the result of extensive research into dyes that meet these requirements and the discovery that the dye of formula (r) is a blue dye with extremely excellent properties as a dichroic dye.

The anthraquinone dye represented by 2 (T) is a compound that completely satisfies the requirements for a dichroic dye applied to the above-mentioned liquid crystal color display device. Examples of the compound represented by formula (I) include 1,4-diamino-N-methyl-2-anthraquinonylcarboxamide, 1,4-diamino-N-ethyl-2-anthraquinonylcarboxamide, 1, 4-Diamino-N-n-propyl-2-anthraquinonylcarboxamide, 1,4-diamino-N
-isopropyl-2-anthraquinonylcarboxamide, 1,4-diamino-N-butyl-2-anthraquinonylcarboxamide, 1,4-diamino-N-t-butyl-2-anthraquinonylcarboxamide, 1,4- Diamino-N-n-hexyl-2-anthraquinonylcarboxamide, 1,4-diamino-N-n-hebutyl-2-anthraquinonylcarboxamide, 1,4-diamino-N-n-octyl-2-anthra Quinonylcarboxamide, 1,4-diamino-N-cyclohexyl-
2-anthraquinonylcarboxamide, 1,4-diamino-N (4/-pentyl-cyclohexyl)-2-
anthraquinonylcarboxamide, 1,4-diamino-
2-anthraquinonycarboxamide, 1,4-diamino-2-methoxycarbonyl-anthraquinone, 1.4
-Diamino-2-ethoxycarbonyl-anthraquinone, 1,4-diamino-2-n-propoxycarbonyl-
Anthraquinone, 1,4-diamino-2-isopropoxycarbonyl-anthraquinone, 1,4-diamino-2
-n-butoxycarbonyl-anthraquinone, 1,4-
Diamino-2-1-butoxycarbonyl-anthraquinone, 1,4-diamino-2-hexyloxycarbonyl-
Anthraquinone, 1,4-diamino-2-n-hebutoxycarbonyl-anthraquinone, 1,4-diamino-2
-n-octoxycarbonyl-anthraquinone, 1,4
-diamino-2-cyclohexyloxyluponyl-anthraquinone, 1,4-diamino-2-(4'-n-pentylcyclohexyloxycarbonyl)-anthraquinone,
Examples include 1,4-diamino-2-phenoxycarbonyl-anthraquinone.

These compounds can be synthesized according to known methods. For example, 1,4-diamino-2-ane I-laquinone carboxylic acid chloride amines or alcohols or phenols are combined with an inert solvent such as benzene, toluene, xylene, chlorobenzene, orthodichlorohenine or nitrobenzene. It can be synthesized by reacting in the presence or absence of a basic catalyst such as sodium carbonate, potassium carbonate, sodium acetate, or pyridine. In addition, after reacting 1-amino-4-ditro-2-anthraquinonecarboxylic acid chloride with amines or alcohols or phenols in the same manner as above, the remaining nitro group is reduced or substituted to convert it into an amino group. It can also be synthesized by The crude dye thus obtained is purified and used by conventional methods such as recrystallization with an organic solvent or column chromatography.

Nematic liquid crystals with positive dielectric anisotropy used in the present invention include, for example, 4-cyano-4'-n-pentylbiphenyl, 4-cyano-4'-n-flopoxybiphenyl, 4-cyano-4'- n-pentoxybiphenyl, 4
-Cyano-biphenyl liquid crystal mixtures such as cyano-47-n-octoxybiphenyl and 4-cyano-4'-n-pentylterphenyl (for example, Merck & Co., Ltd. product code E-8)
), or trans-4-n-propyl-(4-cyanophenyl)-cyclohexane, trans-4-n-
pentyl-(4-cyanophenyl)-cyclohexane,
trans-4-n-hebutyl-(4-cyanophenyl)
-cyclohexane, trans-4-n-pentyl-(4
'-cyanobiphenyl)-cyclohexane and other cyclohexane-based liquid crystal mixtures (for example, Merck & Co., Ltd. product symbol ZLI)
-1132, ZL knee 1840), etc.

Furthermore, when an optically active substance such as cholesteryl nonanoate or optically active 4-cyano-4'-inpentylbiphenyl is added to the liquid crystal mixture, it is in a cholesteric phase state when no electric field is applied, and changes to a nematic phase state when an electric field is applied. It is also possible to use so-called chiral nematic liquid crystal mixtures which undergo phase transformation. The liquid crystal is not limited to the above examples, but other biphenyl liquid crystals, phenylcyclohexane liquid crystals, Schiff base liquid crystals, ester liquid crystals, pyrimidine liquid crystals, tetrazine liquid crystals, and other liquid crystals can be used alone or in mixtures. I can do it.

The dyes according to the present invention may be used alone or in combination of two or more. The concentration of the dye to be used may be within the range in which the dye is dissolved in the liquid crystal and in which the dye molecules can be sufficiently controlled by the alignment of the liquid crystal molecules, but is generally 0.01 to 0.01 to It is preferred to use a concentration of 5% by weight, preferably 0.01-3% by weight. It is also possible to mix the dichroic dye according to the present invention with another dichroic dye or with a non-dichroic dye and use the mixture to obtain a desired hue, and is not limited in this respect.

Furthermore, in producing a liquid crystal display device using the composition of the present invention, liquid crystal molecules and dichroic dye molecules are treated in advance so that they are aligned parallel to the surface of the transparent electrode. Examples of the treatment method include simply rubbing the surface of the transparent electrode in a certain direction with a cotton cloth, etc., applying a silane compound or polyamide compound and then rubbing it with a cotton cloth, etc., vapor depositing silicon oxide, etc. If a solution consisting of a nematic liquid crystal with positive dielectric anisotropy and a dichroic dye of the present invention is used in a liquid crystal color display device which has been treated so that the liquid crystal and dye molecules are parallel to the surface of the transparent electrode as described above, ,
The display device is of a type in which the blue color of the electrode portion disappears when an electric field is applied.

As described above, there are a wide variety of liquid crystals and methods used in implementing a liquid crystal color display device using the composition according to the present invention, but essentially all of them are based on electro-optical methods of nematic liquid crystals or chiral nematic liquid crystals. This can be seen as a display method using the guest-host method using effects. Although typical examples will be specifically described below, the present invention is not limited to these examples in any way.

Example 1 In a small beaker, 68% of 4-cyano-47-n-pentylbiphenyl, 8 parts of 4-cyano-4'-n-pentoxybiphenyl, 23% of 4-cyano-47-n-hebutylbiphenyl, 4 parts -cyano-4'-n-hebutoxybiphenyl 8%, 4-cyano-4/n-octoxybiphenyl 10%, 4-cyano-4'-n-pentylterphenyl 10% and optically active 4-cyano-4 '-Isopentylbiphenyl 5=Lt.

0.1 part of 1,4-diamino-2-anthraquinonylcarboxanilide, which had been sufficiently purified by recrystallization, was added to 99 parts of the liquid crystal mixture, and the mixture was heated to about 80°C to form a completely clear solution. shall be. The contents are then introduced into the liquid crystal cell by known methods such as, for example, capillary action.

1 and 2 are schematic diagrams of a liquid crystal display device having a cell structure. The display device has a layer 1 partially filled with a liquid crystal material colored with a dye. The layer 1 is sandwiched between two parallel rectangular glass slides 2.3. The slides 2.3 are separated from each other by ring-shaped spacers 4 (not shown in FIG. 1) which define the lateral edges of the layer 1.

The slides 2.3 have electrodes 5.6 on their respective inner surfaces. Electrode 5 is connected to external conductor 11 through strip 7 and contact 8 . Similarly, the electrode 6 is connected to an external conductor 12 through a strip 9 and a contact 10. The electrodes 5 and 6 have the same M-shape and are arranged facing each other.

A voltage source 14 and a switch 16 connected in series with the voltage source are connected between external conductors 11 and 12. Voltage source 14 supplies a voltage, either direct current or low frequency alternating current, sufficient to reorient the liquid crystal and dye molecules in layer 1 and place them in the plane of slide 2.3. Typically 1
A voltage of 0 to 20 pols is required.

In the display device shown in FIGS. 1 and 2 as described above, silicon KF-99 (
After coating a silicon-based compound (manufactured by Shin-Etsu Chemical Co., Ltd.), a colored liquid crystal solution, which is the liquid crystal composition according to the present invention, was sealed in the layer 1 portion of the display element, which had been treated to make the liquid crystal alignment as homogeneous as possible.

This display device appeared to be colored bright blue when the switch 16 was open. Close switch 13, 32Hz
When an alternating current voltage of , I DV was applied, the portion of the letter M where the transparent electrodes 5 and 6 faced each other became colorless. When the switch 16 was opened, the blue colored state was shown again. When the display device is placed in the optical path of a spectrophotometer, the maximum absorption wavelength is 614
nm, and at this wavelength, when the switch 13 was opened and closed, the absorbance ratio of the electrodes 5 and 6 was 1:6.9, indicating good dichroism.

Further, the dichroic ratio of this dye in liquid crystal E-8 (trade name of nematic liquid crystal manufactured by Merck & Co., Ltd.) was 10.0. The dichroic ratio is calculated by filling a 10 μm thick glass cell with a nematic liquid crystal solution containing dye at a concentration of 1% in a glass cell whose inner surface has been treated to make the liquid crystal alignment as homogeneous as possible, and using a spectrophotometer to measure polarized light parallel to the liquid crystal alignment. Absorbance measured by directing the liquid crystal (α8.) and absorbance measured by applying polarized light perpendicular to the liquid crystal alignment (α8.)
It is calculated by the following formula from the soil), and is a value that serves as an indicator of the magnitude of dichroism of a dichroic dye.

αU Example 2 The same liquid crystal mixture as in Example 1 was mixed with 1,4-diamino-2-n- which had been thoroughly purified by column chromadog and roughy.
01 parts of propoxycarbonyl-anthraquinone was dissolved and sealed in the same cell as in Example 1. When the switch 13 was opened and closed, the absorbance ratio at the maximum absorption wavelength of 640 nm at the opposing portions of the electrode 5 and B was 4.0, indicating good dichroism.

Moreover, the dichroic ratio of this dye in liquid crystal E-8 is 10.
5 (640 nm), which was an extremely high value.

4. Brief explanation of planes Figure 1 is a front view of the liquid crystal display device, and Figure 2 is a line a-a in Figure 1.
FIG. 2 is a cross-sectional view of the device along , with portions cut away for illustrative purposes.

i ---------------1 liquid crystal and dye layer 2, 3------1-----Glass slide 4
−−−−−−−−−−−−−Spacer 5, 6−−
----------------Electrode 7, 9-----
-m-electrode strip 8, 10---------
One contact 11, 12--1--------Conductor 1ro--11--------Switch 14--
−−1−−−−−−Power supply patent applicant Mitsui Toatsu Chemical Co., Ltd. Figure 1

Claims (1)

[Claims] 1. Nematic liquid crystal with positive dielectric anisotropy has formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (I) (In formula (I), R may be cyclic 1. A composition for a liquid crystal color display, characterized in that it contains dissolved at least one anthraquinone dye represented by an alkyl group or a phenyl group, and X represents an -O- group or an -NH- group.