JPS5936639A - Liquid crystal compound - Google Patents

Abstract

NEW MATERIAL:The liquid crystal compound of formula (R1 and R2 are 1-8C straight-chain alkyl). EXAMPLE:4-n-Pentylcyclohexanecarboxylic acid (4'-n-pentanoyloxyphenyl) ester. USE:Useful as a component of a liquid crystal composition. It has broad liquid crystal temperature range, low melting point and viscosity, and high responce. Especially, a liquid crystal composition containing 5-40wt% of one or more titled compounds is suitable for multiplex driving. PROCESS:The compound of formula can be prepared by reacting a cyclohexanecarboxylic acid having the objective substituent group at the p-position with thionyl chloride, etc., and reacting the resultant chloride with a phenolic compound having a substituent group at the p-position. The esterification reaction is carried out in the presence of a tertiary amine such as triethylamine, or pyridine, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to liquid crystal compounds. More specifically, the general formula R
t-@-coo-@-ocoR1 (However, L, Rlp R2
represents a straight-chain alkyl group having 1 to 8 carbon atoms. ) The present invention relates to a cyclohexanecarboxylic acid ester liquid crystal compound represented by:

Display is achieved by applying an electric field to a thin layer of nematic liquid crystal with a twisted orientation. Display is performed by adding a dichroic dye to a so-called twisted nematic liquid crystal display element, or a nematic or chi-cinematic liquid crystal matrix, and applying an electric field to the thin layer. Liquid crystal compositions used in display devices that use the so-called guest-host effect must be stable against external factors such as moisture, oxygen, light, and heat, and must be stable against external factors such as moisture, oxygen, light, and heat. It is required to have a wide temperature range and excellent multiplex drive characteristics.

Such liquid crystal compositions are generally obtained by combining and mixing several types of compounds having appropriate chemical structures. Compounds and compositions that form a nematic liquid crystal layer include types that have a larger dielectric constant (ε) in the major axis direction than in the minor axis direction of the molecule, that is, have positive dielectric anisotropy (Δε〉0); There is also a type with opposite negative dielectric anisotropy (Δ×0). Compounds of the Δε〉00 type have two i at the end of the long axis of the molecule.
Those having a J group (-CM) are common, △ε
A composition consisting only of the type 〉0 has difficulty in controlling the driving voltage, and also does not have sufficient multiplex driving characteristics. The above-mentioned drawbacks are improved by the addition of compounds of the type ΔSockO. In addition to the above properties, the Δε<0 type requires a wide liquid crystal temperature range, a low melting point, and a low viscosity.

The fi if td general formula R1-■-C(I[], -o-[JR4,
There are mainly nine compounds having an ester bond represented by R2-o-C0O-o-QR6 (Rs-Ratj: I chain alkyl group). In particular, the former is widely used because it has a wide liquid crystal temperature range, relatively low melting point, and low viscosity.

However, when performing multiplex drive, there is a drawback that a large duty ratio cannot be obtained using only the above type.

An object of the present invention is to provide a liquid crystal compound particularly suitable for multiplex driving as a material for such a liquid crystal composition.

Another object of the present invention is to provide a liquid crystal compound having a wide temperature range.

Still another object of the present invention is to provide a liquid crystal compound with a fast response speed.

The present invention is based on the general formula % (11), where RIRl is a linear alkyl 3 having 1 to 8 carbon atoms
− group) is provided as such a liquid crystal compound. The above compound of the present invention is used as a liquid crystal compound,
By composing a liquid crystal composition containing 5% to 40% by weight of one or more of the above compounds, a liquid crystal composition excellent in multi-multiplex driving can be provided.

First, to briefly describe the method for producing the compound of the present invention, a compound obtained by making a chloride of cyclohexanecarboxylic acid having a desired substituent at the para position using thionyl chloride, etc., is reacted with a phenol having a substituent group at the para position. cyclohexanecarboxylic acid phenyl ester. It is well known that during the esterification reaction, the reaction proceeds easily in the presence of a tertiary amine such as triethylamine or pyridine.

Next, the present invention will be explained in detail with reference to Examples.

(Example 1) 4-n-pentylcyclohexanecarboxylic acid (41-
Production of n-pentanoyloxyphenyl) ester.

4- Hyde-quinone IBtf Benzene 501 mA, and Pyridine 20 mA! It was dissolved in While stirring, 14 m of valeric acid chloride (#) was further added dropwise.

After heating under reflux for 1 hour, the mixture was cooled and washed with sodium bicarbonate and dilute hydrochloric acid. Furthermore, wash with water until the liquid becomes neutral, and add anhydrous sulfuric acid)
The benzene layer was dried with IJum.

After distilling off benzene, the temperature was reduced to 165-170°C (
2゜5NjI? ) was collected. The yield was 162.

On the other hand, 4-n-pentylcyclohexanecarboxylic acid 9f
and thionyl chloride at 10 mA were continued to be heated at 40° C. until gas generation stopped. After gas generation has stopped and excess thionyl chloride is distilled off, 110 to 112
C. (1,5-1) range was collected. The collection was 7.5f.

Next, 1.2 t of synthesized 4-valeryloxyphenol
and 4-n-pentylcyclohexanecarboxylic acid chloride dissolved in 1.5f benzene and 20rnJ were mixed, and 20mJ of pyridine was further added and the mixture was heated under reflux for 1.5 hours. After cooling, it was washed with water, diluted caustic 5-soda aqueous solution, diluted hydrochloric acid in this order, and finally washed with water until the liquid became neutral. The benzene solution was dried with anhydrous sodium sulfate, and then the benzene was distilled off. Recrystallize twice each from ethanol and hexane to obtain 4-n
-Pentylcyclohexanecarboxylic M(4'-?L-pentanoyloxyphenyl) ester 0.82 was obtained.

The above compound has a C-S transition point of 54°C and an 8N transition point of 5.
The temperature was 8°C, and the N-■ transition point was 86°C.

1. The infrared spectrum chart of the above compound is shown in FIG. In addition, the above C indicates solid, S indicates smectic, N indicates nematic, and ■ indicates an isotropic liquid phase.

(Examples 2 to 3) In the same manner as in Example 1, 4-n-propyl Schiff true hexanecarboxylic acid (41n-pentanoyloxyphenyl)
Ester, 4-n-propylcyclohexanecarboxylic acid, (4'-n-hexanoyloxyphenyl) ester bond.

*4-n-propylcyclohexanecarboxylic acid chloride L167-69℃ (1,51IJHf
), and 4-n-hexanoyloxyphenol was collected in the range of 175 to 180°C (4wjly). Infrared spectrum charts of each compound are shown in FIGS. 2 and 3, and characteristic values are shown in Table 1 together with the compound of Example 1.

Table 1 Compounds according to the present invention can be combined with other liquid crystal compounds of type △6ku0, such as general formula R5-6-Coo-@-0R4 (Rs
tR4 is a straight-chain alkyl group], and 6g) a liquid crystal compound of the type U, for example, a compound represented by the general formula R
, -o-000-@)-ON, R, (o)@-CN
, R,-@-@-CN.

By mixing with one or more of the compounds represented by Duty can be increased.

(Example 4) A liquid crystal composition using the liquid crystal compound according to the present invention is shown in Table 2 as Example 4. Table 2 also lists the driving characteristics of the liquid crystal composition of Example 4.

The liquid crystal composition shown in Example 4 is Compounds A and B.

It was constructed by mixing and stirring C and D.

Liquid crystal compound A is a liquid crystal serving as a pace. Compound A has a low melting point and heat of fusion, and high transparency. Δε is negative.

Liquid crystal compound B is a liquid crystal compound of the present invention.

By adding Compound B, the liquid crystal composition of Example 4 has a wide temperature range and low viscosity, so the response speed is fast and the driving margin is wide. Δε is negative.

Liquid crystal compound C is added in order to make the current visit anisotropy of the liquid crystal composition of Example 4 positive.

8-A liquid crystal compound is added to increase the clearing point of the liquid crystal composition. While the melting point of general liquid crystal compounds is 60 to 70°C, the melting point of the compound is 100°C or higher, which is a significantly higher property.

In Table 2, the response speed of Example 4 is 9110 m5ec at startup.
, the fall was 89 m, 11 g, and 6. The clearing point of the composition was 74°C, and it remained in a nematic state without crystallization even after being left at -20°C for 96 hours.

The liquid crystal composition according to Example 4 using the compound according to the present invention has a voltage margin of 6e16 or more even in the +duty+bias waveform, and can be effectively used in multi-branch driving when used in combination with a temperature compensation circuit.

The compound according to the present invention tends to be more likely to undergo a smectic phase as the number of carbon atoms in the alkyl group increases, so the length of the alkyl group is preferably 1 to 8 carbon atoms.

[Brief explanation of the drawing]

1 to 3 show Examples 1 to 3 according to the present invention, respectively.
Infrared absorption spectrum agent for compounds corresponding to Patent Attorney Mogami 11-

Claims (1)

[Claims] General formula Rs -@-coo-o-ocou, (R1s
A liquid crystal compound represented by Rsh (straight chain alkyl group having 1 to 8 carbon atoms).