JP3139636B2 - Perfluoroalkyl group-containing azo compound, liquid crystal composition containing the same, and liquid crystal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel red or 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.
On the other hand, as a red-based dichroic dye necessary for forming a black liquid crystal composition, which has great market needs, anthraquinone-based dyes are conventionally known in addition to azo-based dyes.

[0003]

By the way, the guest host (GH) type display system is a twist nematic (TN) type.
There is a problem in that the threshold voltage is generally higher than other methods such as pattern display. This problem is reduced by increasing the dielectric anisotropy of the guest-host liquid crystal composition used. Therefore, a highly practical red dichroic dye having a substituent having a large dielectric anisotropy is desired. However, known dichroic dyes having a nitro group or a cyano group have great difficulties in light resistance and solubility, and have high practical red or blue dichroism having a substituent having a large dielectric anisotropy. Little dye was known. Also, regarding the black liquid crystal composition, azo dyes generally have a problem with light fastness, and anthraquinone dyes with good light fastness have low coloring power, and both are dichroic dyes having the above characteristics. Was not enough. That is, since there are few dyes having particularly high dichroism, high coloring power, and light resistance of a practical level, it has been a great limitation in constituting a black liquid crystal composition. Accordingly, an object of the present invention is to provide a red or blue dichroic dye having less of the above problems, high dichroism, high tinting strength, good solubility and light resistance, a liquid crystal composition containing the same, and a liquid crystal element. Is to provide.

[0004]

Means for Solving the Problems The present inventors have synthesized a novel azo compound having a perfluoroalkyl group having a large dielectric anisotropy at the terminal in the direction of the molecular axis, and used it for a liquid crystal composition and a liquid crystal device. It has been found that the above objects can be achieved by using the compound of the present invention, and the present invention has been completed. The perfluoroalkyl group-containing azo compound of the present invention is a red or blue dichroic dye, and is characterized by being represented by the following general formula (I).

Embedded image (Wherein, R represents an alkyl group, an alkoxyalkyl group, an alkoxy group, a phenyl group substituted with an alkyl, an alkoxyalkyl or an alkoxy, or a cyclohexyl group substituted with an alkyl, an alkoxyalkyl or an alkoxy, and X represents p-phenylene Or 1,4-
Represents a cyclohexylene group, Z ^{1 to} Z ¹² each represent a hydrogen atom, a halogen atom, a methyl group or a methoxy group; and Z ¹ and Z ² , Z ⁴ and Z ⁵ , Z ⁷ and Z ⁸ , and Z ¹⁰ And Z ¹¹ may be linked to each other to form an aliphatic ring, an aromatic ring or a nitrogen-containing aromatic ring, and m is 3
Represents an integer of ~ 18, and n represents 0 or 1. The liquid crystal composition of the present invention includes the above-mentioned perfluoroalkyl group-containing azo compound, and the liquid crystal element of the present invention uses the liquid crystal composition containing the above-mentioned perfluoroalkyl group-containing azo compound. Formed.

Hereinafter, the present invention will be described in detail. In the general formula (I) of the present invention, R represents methyl, ethyl, linear or branched propyl, butyl,
C ₁ -C ₁₈ alkyl groups such as hexyl and octyl; alkoxyalkyl groups such as ethoxymethyl, butoxymethyl, ethoxyethyl and butoxyethyl; methoxy, ethoxy, linear or branched propoxy, butoxy, heptyloxy and the like. A C ₁ -C ₁₈ alkoxy group; an alkyl-substituted phenyl group such as butylphenyl and hexylphenyl;
Alkoxyalkyl-substituted phenyl groups such as ethoxymethylphenyl and butoxyethylphenyl; alkyl-substituted cyclohexyl groups such as propylcyclohexyl, butylcyclohexyl and octylcyclohexyl; alkoxyalkyl-substituted cyclohexyl groups such as butoxyethylcyclohexyl; alkoxy-substituted cyclohexyl groups such as pentoxycyclohexyl Is raised. Z ¹ and Z ² , Z
⁴ and Z ⁵ , Z ⁷ and Z ⁸ , and Z ¹⁰ and Z ¹¹ are each linked to each other to form an aliphatic ring moiety such as a tetralin ring;
An aromatic ring moiety such as a naphthalene ring or a nitrogen-containing heterocyclic moiety such as a quinoline ring may be formed.

The perfluoroalkyl-containing azo compound represented by the above general formula (I) of the present invention is a novel dichroic azo dye and can be synthesized by a known method for synthesizing a known azo compound. That is, a known diazotized coupling is performed using a perfluoroalkyl-substituted aromatic amine obtained by reacting an iodine-substituted aromatic amine such as iodoaniline with an iodoperfluoroalkane in the presence of copper powder. The reaction can be performed by synthesizing perfluoroalkyl-substituted monoazoamines and further performing a diazotization coupling reaction.

The perfluoroalkyl-containing azo compound represented by the above general formula (I) of the present invention has a high affinity for a new fluorine-based liquid crystal, which has attracted attention due to its excellent properties with respect to the TFT system, and has a higher affinity than known dyes. Also have excellent suitability in terms of solubility and the like. Further, when the perfluoroalkyl-containing azo compound of the present invention is used for a fluorine-based liquid crystal, its solubility and two-color are higher than when a known dye having a trifluoromethyl group is used. This has the advantage that the properties are excellent.

The liquid crystal composition of the present invention has the general formula (I)
Are described in, for example, "Liquid Crystal Device Handbook" (edited by the 142nd Committee of the Japan Society for the Promotion of Science (1989); p154-p192).
p715-p722), various liquid crystal compounds or liquid crystal compositions such as biphenyl, phenylcyclohexane, phenylpyrimidine, cyclohexylcyclohexane and the like exhibiting a nematic or smectic phase, or “Naemura;
-116 "or the like, and can be easily prepared by mixing with a known method.

Examples of the liquid crystal used in the present invention include the following.

Embedded image (Wherein R ′ and X ′ are an alkyl group, an alkoxy group, an alkylphenyl group, an alkoxyalkylphenyl group, an alkoxyphenyl group, an alkylcyclohexyl group, an alkoxyalkylcyclohexyl group, an alkylcyclohexylphenyl group, a cyanophenyl group, respectively. A cyano group, a halogen atom, a fluoromethyl group, a fluoromethoxy group, an alkylphenylalkyl group, an alkoxyalkylphenylalkyl group, an alkylcyclohexylalkyl group, an alkoxyalkoxycyclohexylalkyl group, an alkoxyphenylalkyl group or an alkylcyclohexylphenylalkyl group, Represents a hydrogen atom or a halogen atom, and may have an optically active center in these alkyl chains and alkoxy chains;
The phenyl or phenoxy group in R 'and X' is
It may be substituted by a halogen atom such as a fluorine atom and a chlorine atom. Further, the phenyl group in each of the above structural formulas may be substituted with one or two halogen atoms such as a fluorine atom and a chlorine atom.

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 may contain an ultraviolet absorber,
Various additives such as an antioxidant may be contained.

The liquid crystal composition obtained in this manner is sandwiched between at least one of the substrates with transparent electrodes, whereby an element utilizing the guest-host effect (Shoichi Matsumoto, Ichiyo Tsunoda, "Latest Techniques for Liquid Crystals" Industrial Research Council, 34 (198
3); L. Fergason, SID85 Di
guest, 68 (1985), etc.).

1 and 2 show an example of a liquid crystal element to which the present invention can be applied. FIG. 1 is a schematic cross-sectional view in a state where no voltage is applied, and FIG. It is a schematic sectional drawing. In the figure, reference numerals 2 and 2 denote a pair of transparent substrates, on the opposite surfaces of which are provided transparent electrodes 3 each having been subjected to a parallel alignment treatment. This pair of transparent substrates 2
Between them, a liquid crystal composition comprising nematic liquid crystal molecules 4 having positive dielectric anisotropy 4 and dichroic dye molecules 5 is sandwiched to form a liquid crystal element. A voltage from a power supply 10 can be applied to the transparent electrodes 3 and 3 via a switch 11. When the liquid crystal element is irradiated with light through the polarizing plate 8, the incident light 9 is polarized by the polarizing plate 8 in the direction of the arrow 7 and becomes incident polarized light 6 to enter the liquid crystal element. When an appropriate voltage is applied between the transparent electrodes 3 and 3 in this state, the nematic liquid crystal molecules 4 and the dichroic dye molecules are aligned with their long axes perpendicular to the transparent electrode surface. Then, the polarization condition changes, and the liquid crystal element changes from the colored opaque state to the transparent state, and is observed by the observer 1.

[0013]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. Example 1 The following structural formula

Embedded image A perfluoroalkyl group-containing azo compound represented by the formula:
57 g was dissolved in a mixture of 10 ml of acetic acid, 0.53 ml of 35% hydrochloric acid and 10 ml of water, cooled to 0-5 ° C, and 0.15 g of sodium nitrite was added thereto with stirring. After stirring at the same temperature for 2 hours, 0.03 g of sulfamic acid was added to prepare a diazo solution.

On the other hand, the following structural formula

Embedded image Was dissolved in a mixture of 2 ml of N-methylpyrrolidone and 50 ml of methanol to prepare a coupler solution. 0-5 of the above coupler liquid
After cooling to ℃, the above diazo solution was gradually added with stirring, and reacted at the same temperature for 2 hours. After completion of the reaction, cool to room temperature,
After diluting with methanol, the precipitate was filtered, washed with water and dried. The obtained crude crystals were purified by column chromatography,
The following structural formula

Embedded image The azo compound shown by was obtained.

The azo compound obtained as described above is dissolved at a concentration of 1% by weight in a fluorine-based liquid crystal mixture commercially available under the trade name of ZLI-4792 (manufactured by E. Merck) to obtain a red guest host. A liquid crystal composition was prepared. The above-prepared guest-host liquid crystal composition was sealed in a cell having a gap of 9 μm in which a glass substrate with a transparent electrode coated with a polyimide resin, cured, and rubbed was opposed to each other, and the liquid crystal was arranged in parallel. With respect to the obtained cells colored in red, the absorbance for linearly polarized light parallel to the cell orientation direction and the absorbance for linearly polarized light perpendicular to the cell orientation direction were measured, and the order parameter at the absorption peak (λmax 474 nm) was calculated from the following equation. I asked.

(Equation 1) As a result, S = 0.77.

Example 2 Instead of the coupler used in Example 1, the following structural formula

Embedded image Using the coupler indicated by

Embedded image The azo compound shown by was obtained. Using this azo compound,
A liquid crystal cell colored red was produced in the same manner as in Example 1, and the order parameter (S) was measured in the same manner. As a result, S = 0.78 (λmax 470 nm).

Example 3 A diazo solution prepared in the same manner as in Example 1 was added with the following structural formula

Embedded image Is reacted and treated in the same manner as in Example 1 to give a quinoline-based coupler represented by the following structural formula

Embedded image The azo compound shown by was obtained. Using this azo compound,
A liquid crystal cell colored red was produced in the same manner as in Example 1, and the order parameter (S) was measured in the same manner. As a result, S = 0.77 (λmax: 526 nm).

Example 4 The azo compounds shown in the following Tables 1 to 4 were synthesized by the method according to the above example. Fluorine-based liquid crystal mixture of the obtained azo compound: trade name ZLI-4792 (E. Me
Table 1 to Table 5 show the order parameter (S) and the hue in Rck).

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

[0022]

[Table 4]

[0023]

[Table 5]

[0024]

The perfluoroalkyl group-containing azo compound represented by the above general formula (I) of the present invention is a red-blue type dichroic dye having high dichroism and high coloring power. It is useful as a material for a liquid crystal element such as an element. A liquid crystal composition containing the perfluoroalkyl group-containing azo compound, particularly a liquid crystal composition using a fluorine-based liquid crystal, is useful for producing a liquid crystal element such as a display element, and is capable of producing a liquid crystal element having good contrast and the like. Is possible.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a liquid crystal element of the present invention in a state where no voltage is applied.

FIG. 2 is a schematic cross-sectional view of the liquid crystal element of the present invention in a state where a voltage is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Observer 2 ... Transparent substrate 3 ... Transparent electrode 4 ... Nematic liquid crystal molecule 5 ... Dichroic dye molecule 6 ... Incident polarization 7 ... Polarization direction of incident polarization 8 ... Polarizing plate 9 ... Incident light 10 ... Power supply 11 ... Switch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C09B 31/28 C09B 31/28 C09K 19/60 C09K 19/60 A G02F 1/13 500 G02F 1/13 500 G09F 9/35 303 G09F 9/35 303 (56) References JP-A-59-74162 (JP, A) JP-A-63-120761 (JP, A) JP-A-5-230385 (JP, A) JP-A-5-25399 ( JP, A) JP-A-5-51536 (JP, A) JP-A-5-132628 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09B 31/043 C09B 31/053 C09B 31/08 C09B 31/157 C09B 31/18 C09B 31/28 C09K 19/60 G02F 1/13 500 G09F 9/35 303 CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. A compound of the general formula (I) (Wherein, R represents an alkyl group, an alkoxyalkyl group, an alkoxy group, a phenyl group substituted with an alkyl, an alkoxyalkyl or an alkoxy, or a cyclohexyl group substituted with an alkyl, an alkoxyalkyl or an alkoxy, and X represents p-phenylene Or 1,4-
Represents a cyclohexylene group, Z ^{1 to} Z ¹² each represent a hydrogen atom, a halogen atom, a methyl group or a methoxy group; and Z ¹ and Z ² , Z ⁴ and Z ⁵ , Z ⁷ and Z ⁸ , and Z ¹⁰ And Z ¹¹ may be linked to each other to form an aliphatic ring, an aromatic ring or a nitrogen-containing aromatic ring, and m is 3
Represents an integer of ~ 18, and n represents 0 or 1. The azo compound containing a perfluoroalkyl group represented by). 2. A liquid crystal composition comprising the perfluoroalkyl group-containing azo compound according to claim 1. 3. A liquid crystal device using the liquid crystal composition according to claim 2.