JPS58167671A - Liquid crystal composition for cryogenic purpose - Google Patents

Abstract

PURPOSE:A nematic liquid crystal composition that is obtained by mixing compounds represented by specific formula respectively, thus being suitable for use in liquid crystal displays for cryogenic purpose, e.g., displays for cars, because of its stable liquid crystal phases in cryogenic temperature range. CONSTITUTION:The objective composition is obtained by mixing (A) a compound of formulaI(R, R' is alkyl; n is 1-3 integer) such as 1-n-hexyl-4-(4'-methoxymethylphenyl)cyclohexane, (B) a compound of formula II such as (4'-methoxymethylphenyl)-4-propyl-cyclohexanecarboxylate and preferably (C) a compound of formula III such as 1-(4'-n-propylphenyl)-4-benzylcyclohexane. It is preferred that the amount of component B is 30-70wt% based on the total composition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nematic liquid crystal composition for use at extremely low temperatures, which is suitable for liquid crystal display devices that are not sensitive to low temperatures.

Generally, a TN type liquid crystal display device is often used as a liquid crystal display device using nematic liquid crystal.

Until now, liquid crystal display devices have rapidly developed mainly in calculators and wristwatches, and at present, their application to various types of displays mounted on automobiles is progressing as the range of application continues to expand further.

However, in order to be used in such liquid crystal display devices, in addition to the high-speed response and excellent viewing angle characteristics, the most basic drawback of liquid crystal materials, the width of the operating temperature range of liquid crystals, must be met. It is necessary to achieve a narrow solution, that is, as a liquid crystal material, it can be used in extremely cold regions.
It is impossible to withstand use in a temperature range of 0°C to 80°C in extremely hot regions. However, it is almost impossible to achieve both the cryogenic temperature range and the high temperature range at the same time, so we found a liquid crystal composition for cryogenic temperatures and a liquid crystal composition for high temperature use, and then mixed the two to achieve the objective. It is desirable to obtain liquid crystal compositions that are transparent.

So far, in the high temperature range, various types of polycyclic liquid crystal substances having 3 and 4 rings have been discovered, and it is relatively easy to achieve a high temperature of 80°C. For example, there are compounds having three rings. On the other hand, known liquid crystal substances include compounds represented by the following formulas (indicating an alkyl group) and compounds represented by (indicating an -alkyl group). However, such conventional liquid crystal materials have the drawback of crystallization due to insufficient liquid crystallinity in the extremely low temperature region.

The present invention was made in view of the current situation, and
The purpose is to solve the above-mentioned drawbacks, to provide a nematic liquid crystal composition that exhibits a stable liquid crystal phase even in the low temperature range, and is suitable for liquid crystal display devices in which stability in the extremely low temperature range is important.

In order to achieve the above object, the present invention has the following configuration. That is, the cryogenic liquid crystal composition of the present invention (
(a) general formula () (in the formula, R and R' are an alkyl group, n is 1 to 3) (in the formula, R and R' are an alkyl group, n is 1 to 3 )
The cryogenic liquid crystal composition (second invention) of the present invention is characterized by containing a compound represented by the general formula CI)=(wherein R and R' is an alkyl group, n is an integer of 1 to 3.
It is characterized by containing a compound represented by (wherein R and R' represent an alkyl group).

As a result of various studies on the chemical structure of liquid crystal materials for cryogenic use, the present inventors synthesized a liquid crystal compound having a methylene group as a terminal substituent, and a mixed composition of two types (direct bond and ester bond) was obtained. The present invention was achieved by discovering a liquid crystal compound represented by the above general formula and (2) which is effective, that is, exhibits a liquid phase crystal at extremely low temperatures. Furthermore, by using a mixture of these liquid crystal compounds or a compound represented by the general formula [phase] conventionally used therein, a liquid crystal composition that can be used at extremely low temperatures can be obtained. This discovery led to the completion of the present invention.

In the present invention, the alkyl groups of R and R' in the compound represented by the above general formula (I), ' is 1~
5 is preferable.

Examples of liquid crystal compounds corresponding to the above general formula in the present invention include 1-n-pentyl-4-(4'-methoxymethylphenyl)cyclohexa" (PMMC)
, I n-hexyA/-4-(4'-methoxymethylphenyl)cyclohexane, 1-n-hebutyl-4-
(4'-methoxymethylphenyl)cyclohexa7 (
HPMC), 1 n-heptyl-4-(4'-ethoxymethylphenyl)cyclohexane, 1-n-pentyl-4-(4'-7' roboxymethylphenyl)cyclohexane, 1-n-hebutyl-4 -(4'-propoxymethylphenyl)cyclohexane, 1-n-/C-antyl-4-(4'-(β-methoxyethyl)phenylcocyclohexane (PMEC), 1-n-pentyl-4
-(4'-(β-ethoxyethyl)phenyl]cyclohexane, 1-n-pentyl-4-(:4'-(γ-methoxypropyl)phenylcocyclohexane) (PMPC
), I n-heptyl-4-[4'-(γ-methoxypropyl)phenyl]cyclohexane and 1-n-propyl-4-(4'-(γ-ethoxypropyl)phenyl)cyclohexane, or their Mixtures and the like can be mentioned.

In addition, examples of liquid crystal compounds corresponding to the above general formula (1) are -thi
d', Rikoba, (4'-methoxymethylphenyl)-4
-pentylcyclohexanecarboxylate, (4/-
Methoxymethylphenyl'1-4-hebutylcyclohexanecarboxylate, (4'-ethoxymethylphenyl)-4-propylcyclohexanecarboxylate)
(MMCC), (4'-ethoxymethylphenyl)-
4-heptylcyclohexanecarboxylate) (EM
HC), C4'-(β-methoxyethyl)phenyl]
-4-pentylcyclohexane carboxyl/2) (
MEPC), (4'-(β-methoxyethyl)phenyl)-4-hebutylcyclohexanecarboxylate, [
4'-(β-ethoxyethyl)phenyl] -4=pentylcyclohexanecarboxylate, C4'-(γ-
ethoxypropyl)phenyl]-4-hebutylcyclohexanecarboxylate (EPHC) and [4'-(γ
-methoxypropyl)phenyl] -4-hentylcyclohexanecarboxylate or a mixture thereof.

Examples of liquid crystal compounds corresponding to the above general formula [phase] include 1-(4'-n-ethylphenyl) -4
-hentylcyclohexane, 1-(4'-n -7'ropylphenyl'I -4-hentylcyclohexane (P
PTC), 1-(4'-n-)f-enyl)-
4-pentylcyclohexane, 1-(4'-n-pentylphenyl)-4-pentylcyclohexane (PPPC
), 1 (4'-n-hexylphenyl+ -4
-”C-pentylcyclohexane, 1-(4'-n-hebutylphenyl)-4-pentylcyclohexane and t-(
Examples include 4'-1-octylphenyl)-4-pentylcyclohexane and mixtures thereof.

In the present invention, compounds constituting the liquid crystal composition can be used without any limitations as long as they exhibit a nematic phase. Although one type of these compounds may be used, in general, it is advantageous to use two or more types in combination in order to expand the liquid crystal temperature range.

The mixing ratio of the compound represented by the above general formula and the compound represented by the general formula can be selected depending on the purpose, but considering the mutual role of both, the compound represented by the general formula 75
It is desirable to mix it in an amount of 30 to 70 parts by weight based on the total amount of the liquid crystal composition. Further, the combination of the compound represented by the general formula is not particularly limited and can be in any amount.

In Kamoai, the compound of general formula (■) is 30% of the total amount.
It is desirable that the weight is ~70 weights.

The nematic liquid crystal composition of the present invention can be prepared by taking a predetermined amount of each component depending on the purpose, mixing them, and heating and stirring the mixture to make them compatible.

(9) Next, the present invention and its effects will be explained by examples.
The present invention is not limited to these in any way.

Examples 1 to 11 Each component (abbreviated as shown above) was mixed in the composition ratio shown in the table below, and the liquid crystal lower limit temperature and liquid crystal upper limit temperature were measured for each liquid crystal composition. The results are shown in the table below. In addition, regarding the lower limit and upper limit temperature of the liquid crystal, after once crystallizing it using liquid nitrogen using D8C-1500 manufactured by Shinku Riko Co., Ltd., it was gradually heated and the phase transition temperature was measured.

Comparative Examples 1 to 3 Liquid crystal compositions consisting of compounds represented by conventional general formulas and conventionally known compounds without using the components of the general formula ((a) and 0 represented by D and ■) The same measurements as in the above example were carried out using the following. The results are also listed in the table below.

(10) As is clear from the table, the liquid crystal composition of the present invention (Execution 1)
] 1 to 11), it has been confirmed that the lower limit temperature of liquid crystal is much lower than that of conventional ones (Comparative Examples 1 to 3), and the temperature range of usable liquid crystal compositions is also wider. As described above, the liquid crystal composition of the present invention is useful as a nematic liquid crystal composition suitable for TN-type liquid crystal display elements that are unreliable up to extremely low temperatures, and can also be applied to various types of phase change type and guest-host type displays. (12) 451-

Claims (1)

[Claims] 1. (a') General formula (T): (wherein R and R' are alkyl groups, n is 1 to 3 (wherein R and R' are alkyl groups, n is (indicates an integer from 1 to 3)
A liquid crystal composition for cryogenic temperatures characterized by containing a compound represented by: 2, (a) General formula (1); In formula 1, R and R' are alkyl groups, and n is an integer of 1 to 3); (b) General formula ■: (In formula,
R and R' are an alkyl group, n is an integer of 1 to 3) and Cc> General formula [phase]: (wherein R and R' are an alkyl group) A liquid crystal composition for cryogenic temperatures characterized by containing a compound.