JPS59182880A - liquid crystal composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a liquid crystal composition containing an anthraquinone pleochroic dye.

[Background of the invention]

Pleochroic dyes are dyes that exhibit properties that differ in light absorption intensity depending on the direction of the dye molecule. In other words, this dye has the strongest absorption intensity when the direction of the absorption transition moment is parallel to the electric vector of light, and the smallest absorption intensity when the direction is perpendicular to the electric vector of light.

In the liquid crystal display element described above, the orientation of the dye molecules can be changed by utilizing the fact that the alignment direction of the liquid crystal molecules changes when an electric field is applied. Thereby, the color of the liquid crystal display element can be changed by applying dl and pressure. Considering the liquid crystal compound as the host and the dye as the guest, this color change is called the guest-host effect.

Among pleochroic dyes, especially dye C, which has parallel dichroism, the direction of the fall transition moment of visible light is almost parallel to the long axis direction of the molecule, and it dissolves in the host liquid crystal as a guest molecule. When the liquid crystal molecules 11111 are aligned, the long axes of the dye molecules are aligned in the same direction as the alignment direction of the liquid crystal molecules 11111.

Lelye is a liquid crystal composition consisting of parallel dichroic pleochroic dye and N
'Ill In a liquid crystal display element made of a nematic liquid crystal compound with positive anisotropy and subjected to homogeneous alignment treatment, the long axis of the dye molecules forms a homogeneous alignment in which the long axes of the dye molecules are aligned parallel to the electrode plane and in a fixed direction, just like the liquid crystal molecules. do. When white light propagates in a direction perpendicular to the electrode plane and polarized in the same direction as the alignment direction of the liquid crystal molecules through the liquid crystal layer in such an aligned state, its electric vector becomes parallel to the dye molecules. , a specific wavelength range is particularly strongly absorbed, and as a result, the liquid crystal layer takes on a strongly colored state. Next, when an electric field is applied to the liquid crystal layer, the long axes of the dye molecules form a homeotropic alignment because the dielectric anisotropy of the host liquid crystal is positive.

Then, the long axis of the dye molecule is perpendicular to the electric vector of the incident white light, so that the incident light is hardly absorbed by the dye molecule, resulting in the liquid crystal layer being in a weakly colored state.

The guest-host effect is naturally obtained not only by using a nematic liquid crystal compound as described above, but also by using, for example, a smectic liquid crystal compound or a cholesteric-nematic phase transition. In the case of utilizing the phase transition, each molecule of the cholesteritic liquid crystal assumes a helical molecular arrangement in an element subjected to homogeneous alignment treatment. When white light propagates through the liquid crystal layer perpendicular to the IL polar plane, the dye molecules are oriented in various directions, so that the specific wavelength range of all polarized light components is particularly strongly captured by the dye molecules. As a result, the liquid crystal layer becomes strongly colored. Next, when a voltage is applied to the liquid crystal layer, if the dielectric anisotropy of the cholesteric liquid crystal is positive, the helical molecular alignment is dissolved and the long axes of the dye molecules form a homeotropic alignment like the liquid crystal molecules. As a result, the liquid crystal Jψ is in a weakly colored state.

The above pleochroic dyes have (1) high order parameters in the host liquid crystal (represented by the symbol S), (2) sufficient solubility in the host liquid crystal, and (3) high stability against light, heat, and electricity. (4) Two rows of hues are required depending on the purpose. In particular, in order to improve the contrast of the element, at least the above fl) and (2) are required.

The order parameter S is defined by equation (1) and experimentally determined by equation (11). In the formula, the term CO8 is time averaged, θ is the angle between the absorption axis of the dye molecule and the alignment direction of the liquid crystal molecules, and 3p, A/, and A are parallel to the alignment direction of the liquid crystal molecules, respectively. and the absorbance of the dye molecule for vertically polarized light.

5=(3cos2θ-1)/2...
...(I)8=(A/-A soil)/(2A soil+A/)
(In ID parallel dichroic pleochroic dyes, the closer the S value is to the theoretical maximum value l, the less residual color in the weakly colored state, and the brighter the contrast becomes. It is possible to display large and clear images.

[Purpose of the invention]

The object of the present invention is to provide a novel parallel dichroic pleochroic dye that satisfies the requirements (1), f21, and (3) above, a liquid crystal composition that can provide clear display with high contrast, and a display body. There is something to do.

[Summary of the invention]

The relationship between the molecular structure and the properties of pleochroic dyes has not yet been fully clarified, and it is a difficult task to select a pleochroic dye that satisfies all of the above-mentioned performance requirements for a desired hue. By analogy, it is not easy to select from known materials.

As a result of extensive investigation, the present inventors have determined that a saturated or unsaturated ring, i.e., a benzene ring or a cyclohexane ring, is attached to the 2nd or 3rd position of an anthraquinone color image matrix as a linking group -CH2X
(X represents a -CH2- group, an oxygen atom, or a sulfur atom.

), it was discovered that a pleochroic dye with excellent order parameters and solubility, especially excellent order parameters, could be obtained, and the present invention was completed.

That is, the liquid crystal composition of the present invention contains any one of the following: an atom of the general formula 111), an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, and a cyclohexyl group which may be optionally substituted with an alkyl group. An alkyl group having 1 to 18 carbon atoms which may be substituted with an alkoxy group, an alkyl group having 1 to 18 carbon atoms which may be substituted with an alkoxy group, (where R4 is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms which may be substituted with an alkoxy group) group, or an alkoxy group having 1 to 18 carbon atoms.)
, represents a halogen atom, a cyano group or a dialkylamino group. ] and y4 is a hydrogen atom, an amine group, a hydroxyl group, and -0-R5, respectively.
group, Katsutake-NHR' group (where BS is an alkyl group that may be substituted with any one of an alkoxy group, an allyl group, a cycloalkyl group, or a furfuryl group)
- Indicates an aryl group that may be substituted with any one of a rogene atom, an alkyl group, or an alkoxy group, or a cyclohexyl group that may be substituted with an aralkyl group, an alkyl group, or an alkoxy group. ), yl, Y2
, yl, y4 is an amino group, a hydroxy group, a -0-R,5 group, or -N)-IR'
is a group of , Z is a hydrogen atom, a halogen atom, an alkyl group which may be substituted with an alkoxy group, a group of -〇-R', -
8-R1 group, -COOR'-CH2- group, oxygen atom, or sulfur atom. ) is characterized by containing at least one type of anthraquinone thread color system.

More preferably, in the general formula CI) R, 11-
18 alkyl group, an alkoxy group having 1 to 18 carbon atoms, or a cyclohexyl group which may be substituted with an alkyl group. ), 18 alkyl groups, and alkoxy groups having 1 to 18 carbon atoms. )
, a norogen atom, or a dialkylamino group.

], and yl', Yl, y3, and y4 each represent a hydrogen atom, an amino group, and a hydroxy group. Yl, Yl,
Y3.

-CH2X represents any group of R1, and X is -
Represents any one of a CH2- group, an oxygen atom, and a sulfur atom. ) Contains at least one type of anthraquinone dye represented by:

Specific examples of R2 in general formula [I] include a hydrogen atom,
Carbon number 1, such as methyl group, ethyl group, linear or branched propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, dodecyl group, octadecyl group, etc.
~18 alkyl group; cyclohexyl group; methyl group, ethyl M, W-shaped parent is a branched propyl group, butyl group,
Examples of R3 and R4 include alkyl groups having 1 to 18 carbon atoms such as pentyl groups, octyl groups, and octadecyl groups, or cyclohexyl groups substituted with alkoxy groups. Specific examples of R3 and R4 include hydrogen atoms, methyl groups, ethyl groups, and A methyl group, an ethyl group, a linear or branched propyl group, a butyl group, which may be substituted with an alkoxy group such as a linear or branched propyl group, a butyl group, a hexyl group, an octyl group, 1 to 1 carbon atoms such as pentyl group, octyl group, octadecyl group, etc.
8 alkyl group or alkoxy group; halogen atom such as fluorine atom, chlorine atom, bromine atom; cyano group; dimethylamino group, diethylamine group, dibutylamino group, diacylamino group, N-methylethylamino group, Icoumethylbutylamino group and dialkylamino groups such as N-ethylhexylamino groups. Specific examples of R5 include alkoxy groups having 1 to 18 carbon atoms, allyl groups, cyclohexyl groups, 4-n-70 cyclohexyl M, 4
-Cycloalkyl group such as n-hexylcyclohexyl group, alkyl group having 1 to 18 carbon atoms which may be substituted with furfuryl group; halogen atom such as fluorine atom, chlorine atom, bromine atom, alkyl having 1 to 18 carbon atoms an aryl group such as a phenyl group or naphthyl group that may be substituted with a phenyl group or a naphthyl group; or an aralkyl group such as a benzyl group or a phenethyl group; Can be mentioned.

The dye of the general formula [■] is, for example, a dye of the general formula [II] (wherein W represents a halogen atom or a hydroxy group, Yl~4,
Z has the same meaning as in the general formula [I].

) is reacted with a compound represented by the general formula [1% formula% (wherein, Xl has the same meaning as X in the above general formula [1], except for the -CF12- group). Or, the compound represented by the general formula [IV]
] Of(CX2R,” −・・−・−
...-[V] (wherein Xl represents -C)-12-, and R1 has the same meaning as in the general formula [11]. ) under reducing conditions, or by reacting the compound represented by the general formula [VI] 02N OY' Y2ON02 (wherein, Ill, X, Y', Y3.Z have the same meanings as in the above general formula 11). have ) can be produced by reducing the compound represented by

The nematic liquid crystal used in the present invention can be selected from a wide range as long as it exhibits a nematic state within the operating temperature range. Furthermore, by adding an optically active substance to such a nematic liquid crystal, it can be made to take a cholesteric state. Examples of nematic liquid crystals include the substances shown in Table 1 or derivatives thereof.

Table 1 In the above formula, R1 represents alkyl 4 or alkoxy group,
represents a nitro group, a cyan group, or a halogen atom.

All of the liquid crystals in Table 1 have positive dielectric anisotropy, but the known ester-based, azoxy-based, azo-based liquid crystals, which have negative dielectric anisotropy,
Thick yarn, pyrimidine-based, diester-based, or biphenyl ester-based liquid crystals can also be mixed with liquid crystals having positive dielectric anisotropy to form positive liquid crystals as a whole.

Furthermore, it goes without saying that even a liquid crystal with negative diagonal anisotropy can be used as is if an appropriate element configuration and driving method are used.

Host liquid crystal substance U used in the present invention may be any of the liquid crystal compounds shown in Table 1 or a mixture thereof, but the following 4
The liquid crystal substance sold by Merck & Co. under the name ZLI-1132 as a mixture of 196 types of liquid crystal compounds, and the following 44 types:
Br1tish Drug I (o
A liquid crystal material sold under the trade name E-7 by USE Inc. has been found to be particularly useful in the present invention.

Examples of the optically active substance added to the liquid crystal composition of the present invention include chiral nematic compounds such as 2-methyl Δbutyl group,
There are compounds in which optically active groups such as 3-methylbutoxy, 3-methylpentyl, 3-methylpentoxy, 4-methylbutoxy, and 4-methylhectoxy groups are introduced into nematic liquid crystal compounds. Also, alcohol derivatives such as t-menthol and d-borneol, ketone derivatives such as d-camphor and 3-methylcyclohexane, and carboxyl acids such as d-citronellaic acid and di-camphoric acid, as shown in JP-A-51-45546, Acid derivatives, aldehyde derivatives such as d-ciloneral, alkene derivatives such as d-linoneno,
Of course, other optically active substances such as amines, amides, and nitrile derivatives can be used.

As the element used in the present invention, a known liquid crystal display element can be used. That is, generally, transparent electrodes in an arbitrary pattern are provided on two glass substrates, at least one of which is transparent, and a suitable spacer is interposed so that the electrode surfaces face each other.
An element is used in which two glass substrates are arranged in parallel. In this case, the gap between the elements is determined by the spacer. The element gap is 3 to 100
μ is particularly preferably 5 to 50 μIη from Tenkawa's point of view.

Examples of the invention] Below, examples of parallel dichroic and pleochroic dyes used in the liquid crystal composition of the invention and liquid crystal compositions using these dyes will be explained in detail in accordance with the examples. explain.

Example 1 Examples of pleochroic dyes used in the microcrystalline compositions of the present invention are shown in Table 2 along with their hue and order parameters (8).

The characteristics of each dye listed in the 1t2 table are determined by 1i as follows.
It! I'm tired. That is, in the above-mentioned phenylcyclohexane mixed liquid crystal ZLI-1132, as a pleochroic dye,
One of the dyes shown in Table 2 was added, heated to 7° C. or above, stirred well in a state where the liquid crystal became an isotropic liquid, and then left to cool. This process was repeated to dissolve the dye.

The above-mentioned liquid crystal composition prepared in this manner was applied to an inter-substrate gap 10 consisting of three glass substrates, each having a transparent electrode and a homogeneous alignment treatment performed by coating and curing a polyamide resin on the surface in contact with the liquid crystal and then rubbing the same. It was encapsulated in an element of ~100 μm. In the device subjected to the alignment treatment 5Jj, when voltage is applied, the liquid crystal composition assumes a homogeneous alignment jj<4 as shown in FIG. 1, and the dye molecules also assume a similar alignment according to the host liquid crystal.

The groove structure of the liquid crystal display element shown in FIG. 1 is a common one except that the liquid crystal composition of this example is sealed. That is, the device consists of upper and lower transparent glass substrates 1, transparent electrodes 2 formed on each of the substrates, and liquid crystal molecules 3 and pleochroic dye molecules 4 sandwiched between the substrates. and the liquid crystal composition of the example. Incident natural light 5 passes through a polarizing plate 6 and is polarized in an incident light polarization direction 7, reaching the element as incident white polarized light 8. In addition, 9 is an observer.

The absorption spectrum of the liquid crystal composition of this example was measured using light polarized parallel to and perpendicular to the alignment direction of the liquid crystal molecules, and the absorbance A/ of the dye for each of these polarized lights was A and the maximum absorption wavelength were determined. In determining the absorbance of the dye, corrections were made for absorption by the host liquid crystal and glass substrate and reflection loss of the element. Using the absorbance value A/ of the dye for each of the polarized lights and the value on A obtained in this way, the above formula (II) is calculated.
The S value was calculated from

Example 2 A liquid crystal composition obtained by adding 0.8% by weight of the A160 dye shown in Table 2 to the same liquid crystal as that used in Example 1 was sealed in the element used in Example 1, and the same <Same as Example 1> The absorption spectrum was measured. The maximum absorption wavelength in the visible region is 6
36 nm, and the S value of this color system at the maximum absorption wavelength was 0.78.

〔Effect of the invention〕

As described above, the present invention has the advantage that a liquid crystal composition with poor contrast can be obtained.

1 and 2 are schematic cross-sectional views of an example device of the present invention in a state where no voltage is applied, and FIG. l 11 Figure 27 rf f + 2-5-2 Marunouchi, Chiyoda-ku, Tokyo

Claims (1)

[Scope of Claims] 1. General formula [I] Base 1, an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, or an alkyl group having 18 carbon atoms substituted with an alkyl group, and an alkyl group having 1 to 18 carbon atoms; Alkoxy (however, R4 is a hydrogen atom, or has 1 to 1 carbon atoms, which may be substituted with an alkoxy group)
18 alkyl group or an alkoxy group having 1 to 18 carbon atoms. ), halogen atom, cyano group or dialkylamino group. ), and Yl, Y2゜Yl, Y4 are each a hydrogen atom, an amino group, a hydroxyl group, a -0-R5 group, or a -NHFL' group (however,
H, 6 is an alkyl group that may be substituted with any one of an alkoxy group, an allyl group, a cycloalkyl group, or a clylyl group, an aryl group that may be substituted with any one of a halogen atom, an alkyl group, and an alkoxy group; or a cyclohexyl group which may be substituted with an aralkyl group, an alkyl group, or an alkoxy group. ), ¥1
Any one of ゜'y2, Yll, Y4 is an amine group, a hydroxy group, a -0-R' group, or -NH
In the group R,', s, b, z are hydrogen atoms, halogen atoms,
-〇-C of an alkyl group which may be substituted with an alkoxy group
Indicates either a H2- group, an oxygen atom, or a sulfur atom. ) A liquid crystal composition comprising at least one anthraquinone dye represented by: R,2 (However, R,"I'i hydrogen atom, carbon number 1-18
an alkyl group, an alkoxy group having 1 to 18 carbon atoms, or a cyclohexyl group optionally substituted with an alkyl group. , an alkoxy group having 1 to 18 carbon atoms), a halogen atom, or a dialkylamino group. ), Yl,
Y2, Y3, and Y4 each represent a hydrogen atom, an amine group, and a hydroxy group, and Yl, y2, y3, y
Any one of 4 is an amine group or a hydroxy groupD
, z indicates any hydrogen atom, X is -CH, - group,
Indicates either an oxygen atom or a sulfur atom. The liquid crystal composition according to claim 1, characterized in that it contains at least one of the anthraquinone dyes represented by the following.