JPH1095980A - Liquid crystal composition and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a guest-host type liquid crystal composition exhibiting good order parameter over whole light absorption area, capable of exhibiting stability of excellent light resistance, etc., and useful for liquid crystal display elements by combining specific plural dichroic dyes. SOLUTION: This liquid crystal composition contains (A) a compound of formula I [X<1> and X<2> are each OCO, OCH2 , etc.; R<1> and R<2> are each H, a 1-10C alkyl(oxy), a halogen, etc.; R<3> to R<8> are each H, (fluoro)methyl, etc.; ring A is 1,4-cyclohexylene, 1,4-phenylene, etc.], (B) a compound of formula II (R<9> and R<10> are each R<1> , etc.; R<11> to R<16> are each R<3> to R<8> ) and (C) a compound of formula III [X<3> is a single bond, OCO or S; R<17> is H, a 1-10C alkyl(oxy), a 2-10C alkoxyalkyl, etc.; R<18> is R<9> ; R<19> to R<21> is each R<3> , etc.] as dichroic dyes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal composition used for a display device and the like, and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art A guest-host type liquid crystal display device using a guest-host type liquid crystal composition in which a dichroic dye is mixed with a host liquid crystal composition is excellent in a viewing angle or brightness, and is therefore suitable for portable information devices. Attention has been paid to the reflective display used. Since the display quality such as the contrast of the guest-host type liquid crystal display element directly correlates with the dichroism or order parameter of the guest-host type liquid crystal composition to be used, the guest-host type liquid crystal composition showing a high order parameter Has conventionally been required. In particular, recently, there has been a demand for a guest-host type liquid crystal composition that exhibits a high order parameter and that uses a new host liquid crystal composition such as a fluorine-based liquid crystal that can be used for an active driving LCD or the like.

[0003]

However, in a guest-host type liquid crystal composition in which a single dichroic dye is mixed with a host liquid crystal, the order parameter in the entire light absorption region depends on the structure of the dichroic dye used. Is not constant, and there is a problem that the order parameter often decreases in a light absorption wavelength region apart from the main absorption wavelength (λmax). Such a problem is caused by mixing dichroic dyes of various structures and preparing a composition having a hue such as black, brown and dark blue in a wavelength region where the light absorption spectra of the respective dichroic dyes overlap. The order parameter has been reduced, which has been a cause of insufficient contrast of the entire guest-host type liquid crystal composition. Such a phenomenon is remarkable when an azo dichroic dye having a wide light absorption wavelength range is used, and it has been difficult to realize a guest-host type liquid crystal composition exhibiting a high order parameter due to the above reasons.

The present invention relates to a guest having a hue such as black, brown, or dark blue for the purpose of displaying a monocolor display with good visibility, or a multicolor display such as a multicolor display or a full color display by using a micro color filter or the like. An object of the present invention is to provide a guest-host type liquid crystal composition exhibiting high order parameters when a host-type liquid crystal composition is prepared.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problem of the decrease in contrast in a guest-host liquid crystal composition obtained by blending a plurality of dichroic dyes. The present inventors have found that a guest-host type liquid crystal composition obtained by a combination of dichroic dyes has good order parameters over the entire light absorption region, and has excellent stability such as light resistance, and has completed the present invention. Things.

That is, the present invention relates to a guest-host type liquid crystal containing a dichroic dye, wherein a dichroic dye selected from the following groups (A), (B) and (C) is added to each group. And a liquid crystal display device using the liquid crystal composition. (A) Group An azo dichroic dye represented by the following general formula [I].

[0007]

Embedded image

Wherein -X ¹ -and -X ² -are each-
OCO -, - COO -, - OCH 2 -, or, -CH ₂ O
Indicates-. R ¹ and R ² are each a hydrogen atom; an alkyl group or an alkoxy group having 1 to 10 carbon atoms;
12 alkoxyalkyl groups; a halogen atom, or a cyclohexyl group or a phenyl group which may have an alkyl group, an alkoxy group, an alkoxyalkyl group, or a halogen atom as a substituent, and each of R ^{3 to} R ⁸ is a hydrogen atom Or a fluoromethyl group such as a methyl group, a methoxy group, a halogen atom, or a trifluoromethyl group, or the substituents adjacent to R ³ and R ⁴ and R ⁶ and R ⁷ are linked to each other to form a tetralin ring. And an aromatic ring such as a part of a naphthalene ring. (B) Group An azo dichroic dye represented by the following general formula [II].

[0009]

Embedded image

(Wherein R ⁹ and R ¹⁰ are each a hydrogen atom; an alkyl group or an alkoxy group having 1 to 10 carbon atoms; an alkoxyalkyl group having 2 to 12 carbon atoms; a halogen atom or an alkyl or alkoxy group thereof; An alkoxyalkyl group, a cyclohexyl group which may have a halogen atom as a substituent, a phenyl group, a benzyl group or a cyclohexylmethyl group, wherein R ^{11 to} R ¹⁶ are each a hydrogen atom, a methyl group, a methoxy group, a halogen atom, or An aromatic ring such as a part of a tetralin ring or an aromatic ring such as a part of a naphthalene ring, which represents a fluoromethyl group, or a group in which adjacent substituents of R ¹³ and R ¹⁴ and R ¹⁵ and R ¹⁶ are connected to each other; Or a nitrogen-containing aromatic ring such as a part of a quinoline ring.) (C) Group Azo series represented by the following general formula [III] Sex dye.

[0011]

Embedded image

(Wherein, -X ³ -represents a single bond, -OCO-, or -S-; R ¹⁷ represents a hydrogen atom; an alkyl group or an alkoxy group having 1-10 carbon atoms; Alkoxyalkyl group; halogen atom, halogenated alkyl group,
R ¹⁸ represents a halogenated alkoxy group, a halogenated alkoxyalkyl group, or a phenyl group, a cyclohexylphenyl group, or a benzyl group which may have an alkyl group, an alkoxy group, an alkoxyalkyl group, or a halogen atom as a substituent; Is a hydrogen atom;
An alkyl group or an alkoxy group of 2 to 12 carbon atoms; an alkoxyalkyl group having 2 to 12 carbon atoms; a halogen atom, or a cyclohexyl group which may have these alkyl groups, alkoxy groups, alkoxyalkyl groups, and halogen atoms as substituents;
It represents a phenyl group, a benzyl group or a cyclohexylmethyl group. R ^{19 to} R ²¹ each represent a hydrogen atom, a methyl group,
It may represent a methoxy group, a halogen atom or a fluoromethyl group, or adjacent substituents of R ²⁰ and R ²¹ may be linked to each other to form an aromatic ring such as a part of a naphthalene ring. )

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in more detail. The general formula [I] and the general formula [I] used in the present invention.
R ¹ and R ² in the dichroic dyes represented by I] and the general formula [III] are each a hydrogen atom; methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl and octyl A linear or branched alkyl group having 1 to 10 carbon atoms such as a group or a nonyl group; a linear or branched alkoxy group having 1 to 10 carbon atoms corresponding to these alkyl groups; a methoxymethyl group ,
A C2-C12, preferably C2-C10 alkoxyalkyl group such as a methoxyethyl group, a methoxybutyl group, an ethoxymethyl group, an ethoxyethyl group, or an ethoxybutyl group; a halogen atom such as a fluorine atom, a chlorine atom, and a bromine atom A cyclohexyl group; a phenyl group, or a substituted cyclohexyl group having an alkyl group, an alkoxy group, an alkoxyalkyl group, or a halogen atom as a substituent;
Or a substituted phenyl group is mentioned. In addition, as R ¹⁷ , in addition to the groups shown as R ¹ and R ² , a halogenated alkyl group, a halogenated alkoxy group, or a halogenated alkoxyalkyl group, a cyclohexylphenyl group, a benzyl group, and the above alkyl group, An alkoxy group,
Examples thereof include an alkoxyalkyl group, a substituted cyclohexylphenyl group having a halogen atom as a substituent, and a substituted benzyl group.

R ⁹ , R ¹⁰ and R ¹⁸ are each a hydrogen atom; methyl, ethyl, propyl, butyl,
A linear or branched alkyl group having 1 to 10 carbon atoms such as a pentyl group, a hexyl group, a heptyl group, an octyl group, and a nonyl group;
A straight-chain or branched alkoxy group having 2 to 12 carbon atoms, preferably 2 to 10 carbon atoms, such as a methoxymethyl group, a methoxyethyl group, a methoxybutyl group, an ethoxymethyl group, an ethoxyethyl group, and an ethoxybutyl group. Alkyl group; halogen atom such as fluorine atom, chlorine atom, bromine atom, etc .; cyclohexyl group; phenyl group; benzyl group; cyclohexylmethyl group or a substituted cyclohexyl group having any of these alkyl groups, alkoxy groups, alkoxyalkyl groups or halogen atoms as substituents. , A substituted phenyl group, a substituted benzyl group or a substituted cyclohexylmethyl group.

R ^{3 to} R ⁸ and R ^{11 to} R ¹⁶ each represent a hydrogen atom; a methyl group; a methoxy group; a halogen atom such as a fluorine atom, a chlorine atom, and a bromine atom; a monofluoromethyl group, a difluoromethyl group; A fluoromethyl group such as a trifluoromethyl group; further, adjacent substituents R ³ and R ⁴ and R ⁶ and R ⁷ are linked to each other to form a fatty acid such as a tetralin ring as a whole together with the phenylene group to which they are bonded; An aromatic ring such as an aromatic ring or a naphthalene ring, R
¹³ and R ¹⁴ and R ¹⁵ and R ¹⁶ are connected to each other, and together with the phenylene group to which they are bonded, an aliphatic ring such as a tetralin ring, an aromatic ring such as a naphthalene ring or a nitrogen-containing ring such as a quinoline ring. Form an aromatic ring.

In the general formula [I], -X ¹ -and -X ²
-Represents -OCO-, -COO-, -OC
H _2- or -CH ₂ O-, but -X ^1- and-
X ^2-

[0017]

Embedded image

It is preferable that -X ¹ -is -OCO-, -X ² -is -COO-, or -X ¹ -is -OCH _2-. ² - is -CH ₂ O
-Is more preferable. In the general formula [III], examples of —X ³ — include a single bond, —OCO—, and —S—.

Specific examples of each group of dichroic dyes used in the present invention include those shown in Table 1 below.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

In the liquid crystal composition of the present invention, the amount of the dichroic dye is 0.5 to 15% by weight, preferably 0.5 to 5% by weight, based on the liquid crystal composition. As the host liquid crystal material used in the present invention, a fluorine-based Np-type liquid crystal material represented by the following general formula [IV] and containing a liquid crystal compound as a main component,

[0025]

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A cyclohexane ring, a benzene ring, a silacyclohexane ring, a dioxane ring, or a pyrimidine ring;
Represents an integer of 1 to 3. -Z- is a single bond, -COO
—, —CH ₂ CH ₂ —, —CH ＝ CH—, or —C≡C—. Further, at least one of Y ^{1 to} Y ³ is a group selected from a fluorine atom, a fluoromethyl group or a fluoromethoxy group, and the other is a hydrogen atom; an alkyl group having 1 to 7 carbon atoms, an alkoxy group; To 7 alkoxyalkyl groups and alkenyl groups; halogen atoms such as chlorine atoms; substituted alkyl groups having 1 to 7 carbon atoms and substituted alkoxy groups having these alkyl groups, alkoxy groups, alkoxyalkyl groups, alkenyl groups and halogen atoms as substituents. A substituted cycloalkyl group or a substituted alkenyl group having 2 to 8 carbon atoms; a substituted cyclohexyl group or a substituted phenyl group; and Y ⁴ represents an alkyl group having 1 to 10 carbon atoms, an alkoxy group, an alkoxyalkyl group or an alkenyl group. . Or an Nn-type liquid crystal material containing a liquid crystal compound represented by the following general formulas [V] and [VI] as a main component,

[0027]

Embedded image

A cyclohexane ring, a benzene ring, a silacyclohexane ring, a dioxane ring, or a pyrimidine ring;
Represents an integer of 1 to 3. -Z- is a single bond, -COO
—, —CH ₂ CH ₂ —, —CH ＝ CH— or —C≡C—, wherein Y ⁵ and Y ⁶ are a hydrogen atom; an alkyl group having 1 to 10 carbon atoms, an alkoxy group; An alkoxyalkyl group, an alkenyl group, or an alkyl group, an alkoxy group, an alkoxyalkyl group, an alkenyl group, a substituted cyclohexyl group or a substituted phenyl group having a halogen atom as a substituent. Furthermore the Y ⁷ and Y ^8,
At least one of them is a fluorine atom, and the other is a hydrogen atom; a halogen atom such as a fluorine group and a chlorine group;
⁹ and Y ¹⁰ represent an alkyl group having 1 to ¹⁰ carbon atoms, an alkoxy group, an alkoxyalkyl group, an alkenyl group or a substituted cyclohexyl group having these alkyl groups, alkoxy groups, alkoxyalkyl groups, alkenyl groups and halogen atoms as substituents. . Or the following general formulas [VII] and [VIII]
And a cyano-based Np-type liquid crystal material containing a liquid crystal compound represented by the following formula as a main component.

[0029]

Embedded image

A cyclohexane ring, a benzene ring, a silacyclohexane ring, a dioxane ring or a pyrimidine ring;
Represents an integer of 1 to 3. -Z- is a single bond, -COO
—, —CH ₂ CH ₂ —, —CH ＝ CH—, or —C≡C—. Y ¹¹ and Y ^{13 each} represent an alkyl group, an alkoxy group, an alkoxyalkyl group, or an alkenyl group having 1 to 10 carbon atoms; a cyano group; and Y ¹² and Y ¹⁴ represent an alkyl group having 1 to 10 carbon atoms, an alkoxy group, or an alkoxy group. It represents an alkyl group or an alkenyl group. The guest-host type liquid crystal composition of the present invention includes various ultraviolet absorbers and antioxidants, and a steroidal liquid crystal such as cholesteric nonanoate as a chiral dopant and an optically active alkyl group at the terminal substituent of the aforementioned liquid crystal compound. A chiral nematic liquid crystal having a group or an optically active alkoxy group introduced therein may be added up to about 0.1 to 10% by weight based on the liquid crystal composition.

The guest-host type liquid crystal composition of the present invention can be easily obtained by mixing and dissolving the liquid crystal composition with a dichroic dye and various additives by an operation such as shaking. The guest-host type liquid crystal composition prepared in this manner can be used in a TN mode or STN mode, and further edited by the 142nd Committee of the Japan Society for the Promotion of Science;
Nippon Kogyo Shimbun (1989), pages 315 to 329, pages 367 to 370, etc., at least one of which is processed so as to obtain an electro-optical effect such as various guest host modes such as a Heilmeier type guest host and a phase transition type guest host. Are sandwiched between transparent electrode substrates, and various direct drive methods, thin film transistors, and MIMs described in Japanese Society for the Promotion of Science, 142nd Committee, edited by Liquid Crystal Device Handbook, Nihon Kogyo Shimbun (1989), pp. 387-434, etc. Various display elements can be obtained by combining active driving methods using active elements such as the above.

[0032]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. [Example 1] A dichroic dye having the following structural formula shown in Table 1 was mixed with 100 g of a liquid crystal mixture containing a fluorine-based compound as a main component and commercially available under the trade name of ZLI-4792 (manufactured by E. MERCK). By dissolving, a liquid crystal composition-I was prepared.

[0033]

[I-1] 0.65 g [II-1] 0.13 g [II-2] 0.12 g [III-1] 0.21 g [III-2] 0.37 g [III-4] 0 0.22 g [III-5] 0.21 g [III-8] 0.37 g After applying and curing a liquid crystal composition-I with a polyimide resin,
A liquid crystal display device was prepared by injecting into a cell made of a glass plate with a transparent electrode that had been rubbed and subjected to a homogeneous alignment treatment, and the alignment treatment surface of which was made to face the liquid crystal display device.

The absorbance for linearly polarized light parallel to the orientation direction of the colored cell (A parallel) and the absorbance for linearly polarized light perpendicular to the orientation direction of the cell (A vertical) were measured, and the order parameter (S value) in the absorption was measured. Was obtained from the following formula, and as shown in Table 2, good values were obtained over a wide wavelength range. S value = (A parallel-A vertical) / (A parallel + 2A vertical)

[0035]

[Table 6] Further, a light fastness test was performed on the prepared cell using a carbon arc fade meter in accordance with JIS Z8730, and the difference between the light fastness test before and after the light fastness test (ΔE ), The hue change after 100 hours: ΔE (L * a * b * method) is 1.91, and the current value increase rate: I / I0 (applied voltage: 5 V, 32)
Hz) was 1.01 times. [Example 2] A dichroic dye having the following structural formula shown in Table 1 was mixed with 100 g of a liquid crystal mixture containing a Nn-type liquid crystal compound as a main component and sold under the trade name ZLI-2806 (manufactured by E. MERCK). And dissolved to prepare a liquid crystal composition-II.

[0036]

[I-1] 0.45 g [II-1] 0.25 g [III-4] 0.66 g [III-8] 0.77 g This liquid crystal composition-II was treated in the same manner as in Example 1. Thus, a liquid crystal display device was prepared.

Further, as a result of obtaining the order parameter (S value) by the same method as in Example 1, as shown in Table 3, good values were obtained over a wide wavelength range.

[0038]

[Table 8] Further, a light fastness test was performed on the prepared cell in the same manner as in Example 1. As a result, the hue change after 100 hours: Δ
E (L * a * b * method) is 1.66, and the current value increase rate: I / I0 (applied voltage: 5 V, 32 Hz) is 1.41.
It was twice. [Example 3] A dichroic dye having the following structural formula shown in Table 1 was mixed and dissolved in 100 g of a liquid crystal mixture commercially available under the trade name of ZLI-4792 (manufactured by E. MERCK) to obtain a liquid crystal composition-III. Was prepared.

[0039]

Table 9 [I-1] 0.84 g [II-1] 0.12 g [III-4] 0.55 g [III-13] 0.30 g [III-14] 0.30 g [III-20] 0 .55 g A liquid crystal display device was prepared from this liquid crystal composition-III in the same manner as in Example 1.

Further, the order parameter (S value) was determined in the same manner as in Example 1, and as a result, good values were obtained over a wide wavelength range as shown in Table 4.

[0041]

[Table 10] Further, the charge retention characteristics at 25 ° C. and 70 ° C. of the prepared cell were measured as a voltage holding ratio (%) under the following conditions. As a result, good values were obtained as shown in Table-5.

<Voltage holding ratio measurement condition> Applied voltage (pulse amplitude): 5 V Pulse width: 60 μsec Pulse frequency: 3 Hz and 30 Hz

[0043]

[Table 11]

[0044]

As described above, according to the present invention, a guest-host type liquid crystal composition having high dichroism or high order parameter over the entire light absorption wavelength can be obtained, and a guest-host type liquid crystal display device having excellent contrast characteristics. Can be realized.

Claims (2)

[Claims] 1. A guest-host liquid crystal composition containing a dichroic dye, wherein at least one or more dichroic dyes represented by the following groups (A), (B) and (C) are included from each group: A guest-host liquid crystal composition, comprising: (A) Group An azo dichroic dye represented by the following general formula [I]. Embedded image And -X ¹ -and -X ² -are -OCO-,-
COO -, - OCH ₂ -, or shows a -CH ₂ O-. R ¹ and R ² are each a hydrogen atom;
An alkyl group, an alkoxy group; an alkoxyalkyl group having 2 to 12 carbon atoms; a halogen atom, or a cyclohexyl group or a phenyl group which may have an alkyl group, an alkoxy group, an alkoxyalkyl group, or a halogen atom as a substituent. R ^{3 to} R ⁸ each represent a hydrogen atom,
Represents a fluoromethyl group such as a methyl group, a methoxy group, a halogen atom, or a trifluoromethyl group;
Adjacent substituents of ³ and R ⁴ and R ⁶ and R ⁷ may be linked to each other to form an aliphatic ring such as a part of a tetralin ring or an aromatic ring such as a part of a naphthalene ring. (B) Group An azo dichroic dye represented by the following general formula [II]. Embedded image (Wherein, R ⁹ and R ¹⁰ are each a hydrogen atom;
Alkyl group, alkoxy group having 10 to 10 carbon atoms; alkoxyalkyl group having 2 to 12 carbon atoms; halogen atom or any of these alkyl groups, alkoxy groups, alkoxyalkyl groups, cyclohexyl group optionally having a halogen atom as a substituent, phenyl group represents benzyl group or a cyclohexylmethyl group, each R ¹¹ to R ¹⁶ hydrogen atom, a methyl group, a methoxy group, or a halogen atom or a trifluoromethyl group, or of R ¹³ and R ¹⁴ and R ¹⁵ and R ¹⁶ Adjacent substituents may be connected to each other to form an aliphatic ring such as a part of a tetralin ring, an aromatic ring such as a part of a naphthalene ring, or a nitrogen-containing aromatic ring such as a part of a quinoline ring. . (C) Group An azo dichroic dye represented by the following general formula [III]. Embedded image (Wherein -X ³ -represents a single bond, -OCO- or -S-, R ¹⁷ is a hydrogen atom; an alkyl group having 1 to 10 carbon atoms,
An alkoxy group; an alkoxyalkyl group having 2 to 10 carbon atoms; a halogen atom, a halogenated alkyl group, a halogenated alkoxy group, a halogenated alkoxyalkyl group, or a substituent of these alkyl groups, alkoxy groups, alkoxyalkyl groups, and halogen atoms Represents a phenyl group, a cyclohexylphenyl group, or a benzyl group, which may have R ¹⁸ is a hydrogen atom; an alkyl group having 1 to 10 carbon atoms, an alkoxy group; an alkoxyalkyl group having 2 to 12 carbon atoms; Or a cyclohexyl group, a phenyl group, a benzyl group, or a cyclohexylmethyl group which may have an alkyl group, an alkoxy group, an alkoxyalkyl group, and a halogen atom as a substituent. R ^{19 to} R ²¹ each represent a hydrogen atom, a methyl group, a methoxy group, a halogen atom or a fluoromethyl group;
^{Alternatively} , adjacent substituents of R ²⁰ and R ²¹ may be linked to each other to form an aromatic ring such as a part of a naphthalene ring. ) 2. A liquid crystal display device wherein at least one of the guest-host liquid crystal compositions according to claim 1 is sandwiched between transparent substrates with electrodes.