JPH11172252A - Dichroic colorant, liquid composition containing same, and liquid crystal element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dichroic colorant having high dichroism and high tinting power and suited for guest-host liquid crystals. SOLUTION: There is provided an azoic dichroic colorant having a pyrrolidinylnaphthalene as the coupler component. In the formula, X is a hydrogen atom, an alkyl, a cyclohexyl, or the like; Z1 to Z6 are each a hydrogen atom, a halogen atom, methoxyl, or the like, provided that Z1 and Z2 , or Z4 and Z5 may be combined with each other to form an alicyclic ring, an aromatic ring, or the like; n is 0 or 1; and p is a number of 0-2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel red to blue azo dichroic dye, a liquid crystal composition containing the same, and a liquid crystal device.

[0002]

2. Description of the Related Art At present, as a liquid crystal display, a twist nematic (TN) type display mode, a super twist (ST)
Various display modes have been proposed in addition to the N) mode. Among them, a guest-host (GH) type display system using a dye dissolved in a liquid crystal is widely used as a display panel of an automobile or the like because of a feature such as a wide viewing angle. The properties of the dichroic dye used in the GH mode are required to be excellent in the following items: 1) dichroism 2) solubility 3) light resistance 4) coloring power. In forming a black liquid crystal composition, which has a great need in the market, it is usually adjusted by mixing three primary colors of yellow, red and blue dichroic dyes in the liquid crystal.

Azo dyes, which are the mainstream of dichroic dyes, are particularly excellent in 1) dichroism, 2) solubility, and 4) coloring power, and are widely used as yellow to red dyes. Few are practical. A typical azo dye is a so-called intramolecular CT type (Charge Transfer) in which a donor and an acceptor are bound by a conjugated linking group.
Transition), and the tendency is particularly strong for deep-colored azo dyes. It is known that a deeper dye can be obtained by introducing a group having a large electron donating property into a coupler as a donor and a large electron withdrawing group into a diazo component serving as an acceptor. . In other words, to deepen the hue of the dye, it is effective to introduce a nitro group or a cyano group into the diazo component or to use a heteroaromatic ring such as thiazole. And a great difficulty in solubility. In the case of ordinary azo dyes for fibers and the like, introduction of an electron-donating group at the 2, 4, 5-position, etc. of the benzene ring serving as a coupler is effective for deepening the color. In the case of a chromatic dye, introduction of a substituent on the side of the benzene ring tends to cause a great decrease in dichroism. Further, although deepening can be achieved by polyazotization, there is a limitation in deepening, and there is a problem that it is difficult to become a blue dye.

[0004] For this reason, anthraquinone dyes have become the mainstream blue dye. However, anthraquinone dyes have a lower dichroic ratio than azo dyes, have lower solubility, and have lower absorbance than azo dyes, so a large amount of dye is required to obtain the same concentration. It has disadvantages such as an increase in viscosity and a greater dependence on dichroic host liquid crystals than azo dyes. Further, there is a problem that conventional dyes have insufficient affinity such as solubility with respect to fluorine-based liquid crystal used in recent TFT liquid crystal devices and the like.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a red-blue type dichroic dye having less of the above-mentioned difficulties of the dye, a liquid crystal composition containing the same, and a liquid crystal element.

[0006]

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive studies, and as a result, as a coupler component of an azo dye, the following compound

[0007]

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It has been found that the deepening of the color of the dye can be easily achieved by using the compound, and the present invention has been achieved. That is, the gist of the present invention is represented by the following general formula [I]

[0009]

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(Wherein X is a hydrogen atom, an alkyl group, an alkoxy group, an alkoxyalkyl group, an alkylsulfonyl group, a halogen atom, a trifluoromethoxy group, R-OC
O-, R-COO-, Rf-, Rf-S-, Rf-SO
2-, a group represented by Rf-OCO-, wherein R is an alkyl group; a phenyl group optionally substituted with an alkyl group, an alkoxy group, a cyclohexyl group, or an alkylcyclohexyl group;
An alkyl group, an alkoxy group, a cyclohexyl group, a cyclohexyl group optionally substituted with an alkylcyclohexyl group, Rf represents an alkyl group substituted with three or more fluorine atoms, W represents a lower alkyl group, Z ₁
To Z ₃ each represent a hydrogen atom, a halogen atom, a methyl group, a methoxy group or a trifluoromethyl group, and Z ₁ and Z ₂ , Z ₄ and Z ₅ are connected to each other to form an aliphatic ring,
An aromatic ring or a nitrogen-containing aromatic ring may be formed.
-1 and p represent the numbers of 0-2. ), A liquid crystal composition containing the same, and a liquid crystal device.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The azo dichroic dye of the present invention has the following formula [II]

[0012]

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A compound represented by the following formula [III]:

[0014]

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(Wherein X, n, Z _{1 to} Z ₆ , W and p have the same meanings as in the above-mentioned general formula [I]), and a known diazotization coupling reaction is applied. Can be synthesized.

Specific examples of X in the general formula [I] include a hydrogen atom; a methyl group, an ethyl group, a linear or branched propyl group, a butyl group, a heptyl group, an octyl group,
Alkyl groups such as dodecyl group and octadecyl group; alkoxy groups such as ethoxy group and butoxy group; alkoxyalkyl groups such as ethoxymethyl group, butoxymethyl group, ethoxyethyl group and butoxyethyl group; alkylsulfonyl groups such as butylsulfonyl group; Examples of R include a halogen atom such as a fluorine atom and a chlorine atom, and specific examples of R include an ethyl group, a linear or branched propyl group, a butyl group,
Alkyl group such as heptyl group and octyl group; phenyl group substituted by alkyl group such as propyl group, butyl group, heptyl group and octyl group; phenyl group substituted by alkoxy group such as ethoxy group and butoxy group; cyclohexyl group A phenyl group substituted by a cyclohexyl group which may be substituted by an alkyl group such as propylcyclohexyl group or butylcyclohexyl group; an alkylcyclohexyl group substituted by an alkyl group such as propyl group, butyl group, heptyl group and octyl group A cyclohexyl group substituted with an alkoxy group such as an ethoxy group or a butoxy group: a cyclohexyl group substituted with a cyclohexyl group which may be substituted with an alkyl group such as a cyclohexyl group, a propylcyclohexyl group or a butylcyclohexyl group; Concrete Trifluoromethyl groups as, perfluorobutyl group, perfluorohexyl group,
An alkyl group substituted by three or more fluorine atoms such as a 2- (perfluorobutyl) ethyl group;
Specific examples include lower alkyl groups such as a methyl group, an ethyl group and a propyl group, and Z ₁ and Z ₂ , Z ₄ and Z ₅
Are 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 may be formed.

The liquid crystal composition of the present invention comprises an azo dichroic dye represented by the general formula [I] described above, [Liquid Crystal Device Handbook, edited by the 142nd Committee of the Japan Society for the Promotion of Science (1989);
p154 to p192, p715 to p722] and can be easily mixed with various liquid crystal compounds or liquid crystal compositions such as biphenyl, phenylcyclohexane, phenylpyrimidine, and cyclohexylcyclohexane exhibiting a nematic or smectic phase by a known method. Can be prepared.

The host liquid crystal material used in the present invention includes:
A fluorine-based liquid crystal material containing a liquid crystal compound represented by the following general formula [IV] as a main component,

[0019]

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(Wherein ring B is a cyclohexane ring,
Zen ring, silacyclohexane ring, dioxane ring, pirimi
And a q represents an integer of 1 to 3. -Z- is simply connected
In the case, -COO-, -CH_TwoCH_Two-, -CH = CH- or
Represents -C≡C-. Further Y ¹~ Y^ThreeIs a hydrogen atom; charcoal
An alkyl group, an alkoxy group, or an alkoxy group having a prime number of 1 to 7
Alkyl and alkenyl; halogen such as fluorine and chlorine
Atom; these alkyl groups, alkoxy groups, alkoxy
Alkyl, alkenyl and halogen atoms as substituents
A substituted alkyl group having 1 to 7 carbon atoms, a substituted alcohol
Xyl group, substituted alkoxyalkyl group, substituted alkenyl
Group; represents a substituted cyclohexyl group or a substituted phenyl group
Then Y^FourIs an alkyl group having 1 to 10 carbon atoms, alkoxy
Group, alkoxyalkyl group and alkenyl group. )
Or a liquid crystal represented by the following general formulas [V] and [VI]
An Nn-type liquid crystal material containing a compound as a main component,

[0021]

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[0022]

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Wherein ring B is a cyclohexane ring,
Zen ring, silacyclohexane ring, dioxane ring, pirimi
And a q represents an integer of 1 to 3. -Z- is simply connected
In the case, -COO-, -CH_TwoCH_Two-, -CH = CH- or
Represents -C≡C-. Further Y ^FiveAnd Y⁶Is a hydrogen atom;
C1-C10 alkyl group, alkoxy group, alkoxy
Sialkyl group, alkenyl group or their alkyl
Group, alkoxy group, alkoxyalkyl group, alkenyl
Cyclohexyl group having a halogen group or a halogen atom as a substituent
Represents a sil group or a substituted phenyl group. Further Y⁷as well as
Y⁸Represents a hydrogen atom; a halogen atom such as a fluorine group and a chlorine group
Show, Y⁹And Y^TenIs an alkyl group having 1 to 10 carbon atoms,
Alkoxy group, alkoxyalkyl group, alkenyl group
Or an alkyl group, an alkoxy group, an alkoxy
Alkyl, alkenyl, or halogen atoms as substituents
Is a substituted cyclohexyl group. ) Or represented by the following general formulas [VII] and [VIII]
Cyano-based liquid crystal materials containing liquid crystal compounds as main components
Can be

[0024]

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[0025]

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(Wherein ring B is a cyclohexane ring,
Zen ring, silacyclohexane ring, dioxane ring, pirimi
And a q represents an integer of 1 to 3. -Z- is simply connected
In the case, -COO-, -CH_TwoCH_Two-, -CH = CH- or
Represents -C≡C-. Further Y ¹¹And Y¹³Has 1 to 1 carbon atoms
10 alkyl groups, alkoxy groups, alkoxyalkyl
A alkenyl group; a cyano group;¹², Y¹⁴Is carbon
Alkyl groups, alkoxy groups, and alkoxy groups of Formulas 1 to 10
It represents an alkyl group or an alkenyl group. )

The liquid crystal composition of the present invention may contain an optically active compound which may or may not show a liquid crystal phase, such as cholesteryl nonanoate, or various kinds of compounds such as an ultraviolet absorber and an antioxidant. An additive may be contained.
An element utilizing the guest-host effect by sandwiching the liquid crystal composition thus obtained between substrates with at least one transparent electrode [Shoichi Matsumoto, Ichiyo Tsunoda, “Latest Technology of Liquid Crystals”, Industrial Survey Association, 34 (1983); JLFergason, SID85D
igest, 68 (1985), etc.].

[0028]

The present invention will be described more specifically with reference to the following examples. Example 1 An azo compound represented by the following structural formula

[0029]

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0.46 g was dissolved in 15 ml of N-methyl-2-pyrrolidone, and 0.3 ml of 35% hydrochloric acid was added.
After cooling to 5 ° C., an aqueous solution containing 0.08 g of sodium nitrite was added, and the mixture was stirred at the same temperature for 2 hours for diazotization. On the other hand, the following coupler

[0031]

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0.20 g was mixed with a small amount of N-methyl-2-pyrrolidone, added to the above diazo solution, and reacted for about 2 hours. After the reaction, the precipitate was diluted with methanol at room temperature, and the precipitate was filtered, washed with water and dried, and the obtained crystals were purified by column chromatography to give the following structural formula

[0033]

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0.17 g of the above dye was obtained. This azo dye was dissolved at a concentration of 1 wt% in a phenylcyclohexane-based liquid crystal mixture commercially available as ZLI-1565 (trade name, manufactured by E. MERCK) to prepare a blue guest-host liquid crystal composition. A glass substrate with a transparent electrode, which was coated with a polyimide resin, cured and rubbed, faced, and was sealed in a cell having a gap of 9 μm so that the liquid crystal was aligned in parallel. The absorbance (A _// ) of this blue-colored cell for linearly polarized light parallel to the orientation direction and the absorbance (A に 対 す る) for linearly polarized light perpendicular to the orientation direction were measured, and the absorption peak (λma
x: 607 nm) is expressed by the following formula:

[0035]

[Equation 1] S = (A _// −A⊥) / (A _// + 2A⊥)

As a result, S = 0.74.
Trade name ZLI-4792 (E.MERCK) instead of ZLI-1565 above
The order parameters were determined in the same manner using a fluorine-based liquid crystal mixture commercially available as
= 0.75 (λmax 600 nm).

Reference Example In the method of Example 1, the coupler was a dialkyl type coupling component.

[0038]

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Obtained in place of

[0040]

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Phenylcyclohexane liquid crystal mixture of
The hue in the trade name ZLI-1565 (manufactured by E. MERCK) is dark purple, λmax 547 nm.
max was a short wavelength of 60 nm. The order parameter (S) was 0.76. The hue of the dye in a fluorine-based liquid crystal mixture: trade name ZLI-4792 (manufactured by E. MERCK) was dark purple, λmax of 543 nm, and λmax was 57 nm shorter than that of the above Examples. The order parameter (S) was 0.76.

Example 2 Fluorine-based liquid crystal mixture of various azo compounds obtained by a method according to the above-mentioned Example: Order parameter (trade name: ZLI-4792 (manufactured by E. MERCK)) Table 1 shows S) and the hue.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

[Table 4]

[0047]

According to the present invention, a liquid crystal element such as a display element excellent in contrast and durability can be obtained by using the red-blue type dichroic dye having high dichroism and high coloring power and a liquid crystal composition containing the same. Can be configured.

Claims (4)

[Claims] 1. A compound of the general formula [I] (Where X is a hydrogen atom, an alkyl group, an alkoxy group, an alkoxyalkyl group, an alkylsulfonyl group, a halogen atom, a trifluoromethoxy group, R—OCO—, R—C
OO-, Rf-, Rf-S-, Rf-SO2-, Rf-
R represents an alkyl group; an alkyl group, an alkoxy group, a cyclohexyl group, a phenyl group which may be substituted with an alkylcyclohexyl group;
An alkoxy group, a cyclohexyl group, a cyclohexyl group which may be substituted with an alkylcyclohexyl group, Rf represents an alkyl group substituted by three or more fluorine atoms, W represents a lower alkyl group, Z _{1 to} Z ₆ is
Each represents a hydrogen atom, a halogen atom, a methyl group, a methoxy group or a trifluoromethyl group, and Z ₁ and Z ₂ , Z ₄ and Z ₅ are connected to each other to form an aliphatic ring, an aromatic ring or a nitrogen-containing aromatic ring. N may be 0 to 1, p
Represents a number from 0 to 2. An azo dichroic dye represented by). 2. The dye according to claim 1, wherein n is 1
Is a trisazo dichroic dye. 3. A liquid crystal composition comprising the azo dichroic dye according to claim 1. 4. A liquid crystal device using the liquid crystal composition according to claim 3.