JPS59170141A - Liquid crystal of coloring matter - Google Patents

Abstract

NEW MATERIAL:A 4-(trans-4-alkyl cyclohexanoyloxy)3' or 4'-fluoro-azobenzene of formula I (R is 1-15C alkyl; X and Y are such that either of them is F and the other is H). EXAMPLE:4-(trans-4-ethyl cyclohexanoyloxy)-4'-fluoroazobenzene. USE:Orange liquid crystal matter with positive dielectric anisotropy. PREPARATION:For example, 4-hydroxy-3' or 4'-fluoroazobenzene of formula IIis made to react with a trans-4-alkyl cyclohexane carboxylic acid chloride of formula III in the presence of pyridine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel orange liquid crystal material having dielectric anisotropy and a liquid crystal composition containing the same.

Display elements using liquid crystals have come to be widely used in watches, calculators, etc. This liquid crystal display element takes advantage of the properties of optical anisotropy and alielectronic anisotropy of liquid crystal materials, and the liquid crystal phases include nematic liquid crystal phase, smectic liquid crystal phase, and cholesteric liquid crystal phase, among which nematic liquid crystal phase The one that utilizes this is the most widely put into practical use. That is, they include TN (twisted nematic) type, DB type (dynamic scattering type), guest-host type, DAB type, dual-frequency method type, etc., and the properties required of the liquid crystal materials used for each type are different. .

However, in any case, it is desirable that the liquid crystal materials used in these display elements exhibit a liquid crystal phase over as wide a range as possible in nature, but at present there is no single material that satisfies such conditions, and there are only a few. Currently, materials that can be put to practical use are obtained by mixing liquid crystal materials or non-liquid crystal materials.

In addition, these materials must of course be stable against moisture, light, heat, air, etc., and also have a threshold voltage required to drive the display element.

It is desirable that the saturation voltage be as low as possible, and that the viscosity be as low as possible in order to increase the response speed. By the way, in order to widen the liquid crystal temperature range toward high temperatures, it is necessary to use a liquid crystal substance with a high melting point as a component of K, but liquid crystal substances with a high melting point generally have a high viscosity, so the liquid crystal composition containing it also has a high viscosity. As a result, the response speed of liquid crystal display devices that can be used at high temperatures, for example, up to about 80° C., especially at low temperatures, tends to become significantly slower. However, the present inventors have discovered a liquid crystal material that exhibits a liquid crystal phase over a wide temperature range, has a high clearing point, has a low viscosity, and is orange in color, leading to the present invention.

That is, the present invention provides a 4-(trans-4-alkylcyclohexyl group) represented by the general formula (in the above formula, R represents an alkyl group having 1 to 15 carbon atoms, and one of X and Y is F). 3' or 4/-fluoroazobenzene and a liquid crystal composition containing the same.

Most liquid crystal substances conventionally used are colorless or light-colored, but the compound of the present invention is orange and exhibits a liquid crystal phase up to high temperatures, so adding it as a component to a liquid crystal composition can give it color. did. It is possible to create a composition that exhibits a liquid crystal phase up to high temperatures, and it is possible to create a display device with a different appearance than conventional ones. Furthermore, since the compound of the present invention has a low viscosity, it hardly increases the viscosity of the liquid crystal composition.

Next, a method for producing the compound of the present invention will be described. Manufactured by known methods. 4-Hydroquine-3' or 4'-fluoroazobenzene is reacted with trans-4-alkylcyclohexanecarboxylic acid chloride in the presence of pyridine to obtain the desired 4-(trans-4-alkylcyclohexanoyloxy)-3.
'Also, 4'-fluorobenzene was produced. The above is represented by a chemical formula: (In the above formula, R, X, and Y are the same as above.) Hereinafter, the compound of the present invention will be explained in more detail with reference to Examples.

Example 1 (Production of 4-(,) lance-4-ethylcyclohexanoyloxy) 4/-fluoroazobenzene 4-hydroxy-4'-fluoroazobenzene 2.21
Dissolve pyridine 1cldK. This solution K) 7 tons 4-ethylcyclohexanecarboxylic acid chloride l・7t
Add and incubate overnight.

200 ml of toluene is added and the toluene layer is washed in a separatory funnel first with 6N hydrochloric acid, then with 2N sodium hydroxide solution and finally with water until neutral. After drying it over anhydrous sodium sulfate, the toluene layer is removed under reduced pressure. The precipitated crystals are recrystallized with ethanol to obtain the desired 4-(trans-
4-ethylcyclohexyloxy) 4t-fluoroazobenzene was obtained. Yield 2.5F, yield 71%. or,
The C-N point of this product was 97.3 to 98.0°C, and the N-1 point was 1903°C.

Examples 2 to 6 In the same manner as in Example 1, lance-
Using trans-4-alkylcyclohexanecarboxylic acid chloride having another alkyl group in place of 4-ethylcyclohexanecarboxylic acid chloride, other 4-()trans-
(4-alkylcyclohexanoyloxy)-47-fluoroazobenzene t-, or 4-()-lanth-4-alkylcyclohexane using 4-hydroxy-3'-fluoroazobenzene instead of 4-hydroxy-4'-fluoroazobenzene. Sanoyloxy)-3'-7A oroazobenzene was produced. The above physical property values are shown in Table 1 together with the results of Example 1.

Example 7 (Usage example) Trans-4-globyl-(4/-cyano7enyl)cyclohexane 28 thitrans-4-benzyl(4'-cyanophenyl)cyclohexane 42% trans-4-heptyl(4 The nematic clearing point of the liquid crystal composition is 52°C. When this liquid crystal composition was sealed in a TN cell (twisted nematic cell) with a cell thickness of 10 μm, the operating threshold voltage was 1.53 V.

The saturation voltage was 2.12V. Also, the viscosity is 1i at 20℃
It was 3 cp.

To 95 parts of this liquid crystal composition was prepared in Example 1 &4-()lance-4-probylcyclohexanoyl okino) 4
/- The liquid crystal composition to which 5 parts of fluoroazobenzene was added was colored orange, its nematic clearing point rose to 58°C, the threshold voltage was 1.56V, and the saturation voltage was 2. L 6
It was V. The viscosity was 26 cp at 20°C.

Claims (2)

[Claims] (1) 4-(trans-4-alkylcyclohexanoyloxy) represented by the general formula (in the above formula, R represents an alkyl group having 1 to 15 carbon atoms, and either X or Y is F) 3/C4'-Fluoroazobenzene. (2) 4-(trans-4-alkylcyclohexanoyloxy ) A liquid crystal composition characterized in that it contains at least one type of 3/4'-fluoroazobenzene.