JPS6160113B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to new nematic liquid crystal materials. They can be used in electro-optical devices for the modulation of transmitted or incident light or for the display of numbers, symbols, images, and also as alignment media in spectrometry, gas chromatography. It is already known in the prior art that nematic liquid crystals change their orientation in an electric field and that this change can be applied to the fabrication of electro-optical devices (M. Tobias, “International
``Handbook of Liquid Crystal Displays'', published by Ovum Publishing, London, 1976).Furthermore, liquid crystals can be used for spectroscopic measurements in the visible and near ultraviolet regions,
It is advantageously used as an orientation medium in nuclear magnetic resonance and gas chromatography (G., Meyer,
(Applications of Liquid Crystals by E. Szatzkman, J. E., and G. Grapmeier, published by Springer Verlag, Berlin-Heidelberg-New York, 1975). To date, substituents of benzoic acid phenyl ester have often been used for the above-mentioned purposes (East German Patent Application WP 86269, R. Schütteinschütresser, Zeitschrift Führer Natsühlforschung). Magazine 27b, 774
(1972). These esters have a relatively high viscosity, which causes long rise and fall times that are undesirable as components of electro-optic devices at low temperatures. Some of these esters have undesirably low clearing temperatures or have too high melting points. The object of the present invention is to have a powder that is chemically or thermally stable, has no inherent color in the visible spectrum, has a sufficiently high clearing temperature, a sufficiently low melting point, and a low viscosity, and that Suitable for use in electro-optical devices for the modulation of light or for the reproduction of numbers, symbols, images, as well as spectroscopic measurements,
The object of the present invention is to develop new liquid crystal materials that are also suitable as alignment media for gas chromatography. The inventor has determined that the general formula

[Formula] or [In the formula, R ¹ is n (normal)- where n is 1 to 8
C _o H _2o+1 −, R ² is n where n is 1 to 8
-C _o H _2o+1 -, n-C _o H _2o+1 O- or -CN only in the former formula, and X is

[expression] or

[Formula], R ³ means -H, -CH ₃ , -C ₂ H ₅ or -CI, R ⁴ is n-C _o H _2o+1 -, n where n is 1 to 8; −
C _o H _2o-1 O-. ] It has been discovered that a new nematic liquid crystal material represented by the following formula satisfies this problem. This liquid-crystalline material has high chemical and thermal stability, has no substance-specific color in the visible spectral region, has a sufficiently high transparency temperature, a sufficiently low melting point and a low value of viscosity. It can be used in electro-optical devices for modulating transmitted light or incident light or for reproducing numbers, symbols, and images, and can also be effectively used as an alignment medium for spectroscopic measurements and gas chromatography. By creating mixtures, especially eutectic mixtures,
It is possible to further significantly lower the melting point and substantially widen the operating temperature range even further with little change in the clearing temperature. The transition points of representative examples of the liquid crystal materials of the present invention are shown in Tables 1 to 3 below. The melting points, liquid crystal transition points, and clearing temperatures in Tables 1 to 3 were measured at elevated temperatures using a polarizing microscope equipped with a heated stage.

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[Table] Production example 1 General formula In

The compound corresponding to [Formula] is a 4-linear alkylcyclohexanoyl chloride in which the R ¹ group has the meanings listed in numbers 1 to 70 in Table 1, and the R ² and R ³ groups correspond to those in Table 1. It was prepared by the following reaction from the substituted product of 4-hydroxybenzoic acid phenyl ester having the meaning indicated in the place of the number. The reaction was carried out in pyridine at room temperature and the product was purified by repeated recrystallization from methanol. The physical properties of the products Nos. 1 to 70 obtained are as listed in Table 1. Manufacturing example 2 General formula In

The compound corresponding to [Formula] is a 4-linear alkylcyclohexanoyl chloride in which the R ¹ group has the meanings listed in Nos. 71 to 91 in Table 2, and the R ² and R ³ groups have the corresponding numbers. (wherein R ² means the same group as R ¹ ) and 2-substituted hydroquinone having the meaning described in (herein, R 2 means the same group as R 1 ) by the following reaction. The reaction was carried out in pyridine at room temperature and the product was purified by repeated recrystallization from methanol. The physical properties of the products Nos. 71 to 91 obtained are as listed in Table 2. Usage Example 1 The substance No. 77 in Table 2 exhibits dynamic scattering in a normal electro-optical device. Threshold voltage U ₀ at 50Hz alternating voltage
is 7.5V, and the threshold voltage U ₀ at DC voltage is 5.5V (The temperature used when measuring the threshold voltage is 20°C. The same applies hereinafter.) When the voltage is increased to 2.5 times U ₀ , the contrast ratio is An excellent value of 20:1 or more was obtained. However, no decomposition phenomenon was observed even when voltages up to 60V were applied. Usage example 2 The material No. 93 in Table 3 has positive dielectric anisotropy and has a field effect (Fresdericksz dislocation, Schadt-
It is suitable for use in electro-optical devices based on the Helfrich effect, Guest-Host effect). For one Schadt-Helfrich cell (torsion cell) the threshold voltage is 4V/50Hz and a complete reversal of the configuration is 8V/50Hz.
achieved in Hz. Usage Example 3 1% methyl red was added to the substance No. 93 in Table 3 to create an oriented preparation with layers parallel to the plate. When transmitting polarized light whose plane of polarization is parallel to the preferred direction of the nematic layer, an absorption band typical of methyl red was found. In contrast, no absorption was detected when light with a plane of polarization perpendicular to the preferred direction of the nematic layer was transmitted. The appearance of dichroism in the dye methyl red is due to the dye molecules being oriented and encapsulated in accordance with the orientation of the nematic matrix. Since the liquid crystal material of the present invention exhibits no absorption in the visible spectrum region, it is suitable for use in spectroscopic measurements in the visible region. When used as a component of an electro-optical device, the layer that is initially parallel to the plate can be made vertical with the help of an electric field (5V/50Hz), resulting in a color change from red to pale rose. It will be done.

Claims (1)

[Claims] 1 General formula [formula] or [In the formula, R ¹ means n-C _o H _2o+1 - where n is 1 to 8, and R ² means n-C _o H _2o+1 where n is 1 to 8
-, n-C _o H _2o+1 O- or -CN only in the former formula, X means [formula] or [formula], R ³ means -H, -CH ₃ , - C ₂ H ₅ or -Cl, R ⁴ is n-C _o H _2o+1 -, n- where n is 1 to 8;
C _o H _2o+1 means O-. ] A liquid crystal material represented by .