JPS59182878A - Liquid crystal composition - Google Patents

Abstract

PURPOSE:To prepare a liquid crystal composition having remarkably improved order-parameter value and excellent display contrast, by adding a polychromatic dye composition containing a polychromatic dye having a group of a specific formula to a liquid crystal compound used as a host substance. CONSTITUTION:The objective liquid crystal composition is prepared by adding (A) a polychromatic dye composition containing a polychromatic dye having the group of formula I [A<0> and A<2> are group of formula II (Z<1>-Z<3> are H, halogen, alkyl, alkoxy, hydroxy, acylamino or cyano; Z<1> and Z<2> may together form an aromatic ring); A<1> is -NH-CH2- or -CH2-NH-; X<0> is H, (substituted) alkyl, (substituted) alkoxy, aryl or halogen] to (B) a liquid crystal compound used as the host substance. The dye having the group of formula I is preferably the one represented by formula III [W is group of formula I ; B is -COZ<4> (Z<4> is O, S, -CH2-, etc.), etc; Y<1>-Y<4> are H, amino, etc.; Y<5> is H, halogen, etc.; X<1> is H, cyano, etc.; lis 0 or 1].

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of [Example 19]] The present invention relates to a guest-host type liquid crystal composition used in a liquid crystal display element capable of color display.

[Background of the invention]

A guest-host type liquid crystal composition is a liquid crystal composition in which a pleochroic dye as a guest substance is dissolved in a host liquid crystal as a matrix. This pleochroic dye requires high order parameters in the host liquid crystal.

The order parameter (hereinafter referred to as S) is expressed by formula (I)
It is experimentally determined using equation (H). In the formula, the CO32θ term is statistically averaged, θ is the angle between the absorption axis of the guest dye molecule and the alignment direction of the host liquid crystal molecules, and A/ + A□ is the angle between the absorption axis of the guest dye molecule and the alignment direction of the host liquid crystal molecules, respectively. It is the absorbance of a dye molecule for light polarized parallel and perpendicular to the opposite direction.

5=(3(AS2θ-1)/2 -...
(1) S = (A, -A) / (2A + A,)...
(II) S represents the degree of parallelism of the dye molecule absorption axis with respect to the alignment direction of the host liquid crystal molecules, and is an amount that controls the display contrast in a guest-host type liquid crystal display element. In the case of pleochroic dyes with parallel dichroism, as the value approaches the theoretical maximum value of 1, the degree of residual color in the white areas decreases, making it possible to display brightly and clearly with high contrast. Become.

The relationship between the molecular structure of pleochroic pigments and their properties has not yet been fully clarified. Selecting a pleochroic dye having a high S value in a desired hue is a difficult task, and making an analogy from known materials is also a difficult task.

[Purpose of the invention]

The main object of the present invention is to develop a liquid crystal composition for a guest-host liquid crystal display using a novel pleochroic dye with a large S candy, making full use of the known pleochroic dye structure and the various hues associated therewith. It is about providing.

[Summary of the invention]

As a result of extensive studies, the present inventors have found that the S value, which characterizes pleochroic dyes, can be significantly improved by introducing a benzene ring or cyclohegizane M into the dye matrix through an NII CH2- bond, and the present invention has been completed.

The above-mentioned knowledge of molecular borrowing for improving the S value disclosed in the present invention was completely unknown in the field of pleochroic dyes, and we will continue to make use of this knowledge. It is expected that the economic benefits that will be obtained will be extremely large.

As is clear from the following comparative example, the fact that the dye of the present invention containing an -NHCH2- group exhibits a high S value cannot be expected from the prior art.

Ugly 6th army
The hue and tone of the two dyes compared in each row of 7 rows of 4 to 5 colors were almost the same in all cases.

In addition, the value of the order parameter of each dye in the above seven examples is based on the commercially available phenylcyclohexane-based ZLI described below.
This value is measured at room temperature (25C) using a mixed liquid crystal called -1132 (manufactured by Merck & Co.) as the host a-crystal.

The benzene ring and cyclohexane component of the dye molecule -N H-
It has been found that the phenomenon that the order parameter improves when bonded through a CH*-bond is not limited to the above example, but is observed in almost all pleochroic dye systems known to date.

Prior to the present invention, the 4f effect as discovered in the present invention had not been demonstrated in the field of guest-host type liquid crystal displays.

The host component that can be used in the present invention is characterized in that it contains at least a dye having a group represented by the following formula [I]. That is, -AO-A'-A2-XO[I]Z3, AI represents -NHCH2- or -CH2NH-, and Xo represents a hydrogen atom, an alkyl group (including a cycloalkyl group), or an alkyl group having a substituent. (1 refers to an alkoxyalkyl group, an aryloxyalkyl group, a dialkylaminoalkyl group, an arylaminoalkyl group), an alkoxy group, an alkoxy group having a substituent (e.g. an alkoxyalkyl group), an aryl group, a halogen atom,
Z1 to Z3 are hydrogen atoms, halogen atoms, alkylno, 1
(a) represents an alkoxy group, a hydroxy group, an acylamino group, or a cyano group, and zl and A2 may be linked to each other to form an aromatic ring. )! Dyes represented by the following general formulas [■] to [M] are recommended for I\.

[■]

o7　　　　　　　　　(IX)]1 (21) (The symbols in each formula are as follows.

W: NoiL represented by the general formula [■].

B i COZ', Z5CO, 'CH2Z'
, Z5C) 12~.

A group selected from A4, A5, oxygen atom, sulfur atom, CH
2-no, ) 2 and lj- to I is also one group, 1 mo 1: hydrogen atom or lower alkyl group, "; ]: +2
i is 3, l; 0 or 1, y I , y 2 , y 3 , y 4 , hydrogen atom, amino group or hydroxy group, any one of which is an amino group or hydroxy group, ￥ 5; Hydrogen atom, halogen atom, alkoxy group or -(-H+W group, y6, y7, amino group - or hydroxy group,
y8, ylo, hydrogen atom, amino group or hydroxyl J, i;, *J1 X'HX' i Hydrogen atom, Rogen atom or alkoxy group, X5; r"il elementary atom (or -sulfur atom,
Hydrogen atom or hydroxy group; The nematic liquid crystal (alkoxy group or 1B+W group) used in the present invention can be selected from a fairly wide range as long as it exhibits a nematic state within the operating temperature range. Furthermore, by adding an optically active substance, which will be described later, 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 and these inscriptions.

Table 1 In the above table, t' represents an alkyl group or an alkoxy group,
X represents a nitro J11, cyano, or nitrogen 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,
Liquid crystals based on polyurethane, pyrimidine, diester, or biphenyl ester can also be used by mixing them 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 induced anisotropy can be used as is if an appropriate element configuration and driving method are used.

The host liquid crystal substance used in the present invention may be any of the liquid crystal compounds shown in Table 1 or a mixture thereof, but the following four
As a mixture of liquid crystal compounds of ridges, there is a liquid crystal substance sold by Merck & Co. under the trade name ZLI-1132, and as a mixture of the following four types of liquid crystal compounds, 13ritish, [)rug)
(A liquid crystal material sold under the trade name E-7 by Ouse Corporation has been found to be particularly useful in the present invention.

Examples of the optically active substance used in the present invention include chiral nematic compounds such as 2-methylbutyl group, 3-methylbutoxy group, 3-methylpentyl group, 3-methylpentoxy group, 4-methylhexyl group, 4-methylhexyl group, and 4-methylhexyl group. There are compounds in which optically active groups such as groups are introduced into nematic liquid crystal compounds. Also, alcohol derivatives such as menthol and d-borneol shown in JP-A No. 51-45546, d-
- Ketone derivatives such as camphor, 3-methylchlorohexane, (lubobon-resistant inducers such as 1-citronellaic acid and t-camphoric acid, aldehyde derivatives such as d-citronellal, alkene derivatives such as d-linonene, etc.) Of course, 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, in general, transparent electrodes in an arbitrary pattern are formed on two glass substrates, at least one of which is transparent: Nj+:
Then, place the device so that the two glass substrates are parallel to each other with a suitable spacer in between so that the electrode surfaces face each other.
The one made by ¥ is used.

In this case, the spacer defines the gap between the elements. The element gap is 3 to 100μm1!1.1
5 to 5071 m is preferred from a practical standpoint.

[Embodiments of the invention]

Examples of dyes used in the present invention and liquid crystal compositions using these dyes will be specifically explained below using Examples.

First, Table 2 shows examples of pleochroic dyes used in the present invention, along with their hues and order parameters.

The th properties of each dye listed in Table 2 were investigated as follows. That is, any of the dyes shown in Table 2 was added as a pleochroic dye to the above-mentioned phenylcyclohexane mixed liquid crystal Z, LI-1132, and the dyes were dissolved by stirring well at room temperature.

The liquid crystal composition thus prepared has a transparent electrode, and a polyamide resin is coated on the surface in contact with the liquid crystal, cured, and rubbed to homogeneously align the substrate. It was encapsulated in an element of 10 to 100 μm. When no voltage is applied in the element subjected to the alignment treatment, the liquid crystal composition maintains a homogeneous alignment state in which the liquid crystal molecules and dye molecules are aligned parallel to the electrode surface and in a fixed direction, and the dye molecules also follow the host liquid crystal. take the orientation.

The absorption spectrum of the guest-host device thus prepared was measured using light polarized parallel to and perpendicular to the alignment direction of the liquid crystal molecules, and the dyes for each of these polarized lights were measured. The maximum absorption wavelength was determined based on the absorbance of A7 and A.

When determining the absorbance of the dye, 1#-I is taken into account the absorption by the post liquid crystal and glass substrate and the reflection loss of the element.
I made a correction. The value of the order parameter S was calculated from the above-mentioned formula by subtracting @A7 and A□ of the absorbance of the dye for each polarized light thus obtained by /l'l.

[Effect of I and Akira 1 hair]

Claims (1)

[Claims] 1. A liquid crystal compound is used as a host substance, and a guest substance J (
In the liquid crystal composition in which a pleochroic dye is added as 7j, the pleochroic dye has at least the following general formula % [1] CH2N l-1-, and Xo is a hydrogen atom, an alkyl
group, @ substitution a alkyl group, alkoxy group, '5,
Indicates an alkoxy group, an aryl group, or a halogen atom having a substituent, Z1 to Z3 are hydrogen atoms, and Halokene JJ7<
child, alkyl J, f, , alkoxy group, hydroxyno dj, acylamino group, cyano group
l may be linked to each other to form aroma 11j, M. ) A liquid crystal composition comprising a pleochroic dye having one group represented by the following. 2. In claim 1, the general formula [
■] In the formula, XO is an alkoxyalkyl group, an aryloxyalkyl group, a dialkylaminoalkyl group, an arylaminoalkyl group, a cycloalkyl group, or an alkoxyalkyl group. 1, the judgment against Toshōkoku. 3. In claim 1, the general formula [
The dye having the group represented by I] has the following general formula [■] ~
[XI) Y'0Y1 0 Y' li (the symbols in each formula are as follows. W: a group represented by the general formula Ell, T3; COZ', Z5CO, C) hZ',
Z5CII2゜-Q, S, CH2
, N.H. A group selected from -0COO-, Z' I Z'; oxygen atom, sulfur atom, CH
2- group or -NH,- group, R+'; lower alkyl group, m; 1
, 2'j Puma: N2 3, t; o-i/ζ is 1, Y', Y2. Y3. Y', a hydrogen atom, an amino group or a hydroxy group, any one of which is an amino group or a hydroxy group, Y5; a hydrogen atom, a halogen atom, an alkoxy group or a husband of +413-)-W, y6, y7, amino 7 groups or hydroxy group, y
8, ylo, hydrogen atom, amine group, hydroxy group, Y9; hydrogen atom, amine group, hydroxy group, or X5; hydrogen atom, hydrogen atom, or cyano group, X2
;Hydrogen atom, hydrogen atom, alkoxy group or 1,000 B
Group of W, x3. x', hydrogen atom, norogen atom or a
alkoxy group, X5; oxygen atom or sulfur atom, X6; hydrogen atom or hydroxy group,
Alkyl group, alkoxy group, or other than 10. X13; hydrogen atom, argyl group, alkoxy group or R,
3. Hydrogen atom, halogen atom, alkoxy group or +B
-)--W group) A liquid crystal composition characterized in that it is selected from those represented by the following.