JPS60195183A - Liquid crystal composition - Google Patents

Abstract

PURPOSE:To provide a liquid crystal composition containing trans-4-n-alkyl-(4- cyanophenyl)cyclohexane, etc., and suitable for an active matrix-type TN-FEM integrated with a switching element. CONSTITUTION:The objective liquid crystal composition contains (A) one or more compounds of formula I (n is 3, 5 or 7), (B) one or more compounds of formula II (m is 2, 3, 4 or 7), (C) one or more compounds of formula III (p is 3 or 5; q is 2 or 4), (D) the compound of formula IV, (E) the compound of formula V, and (E) the compound of formula VI. EFFECT:It has low viscosity, low refractive index anisotropy, and high K33/K11 ratio of elastic moduli.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a liquid crystal composition for an electro-optical display device, and more particularly to a liquid crystal composition for an active matrix TN-FEM incorporating a switching element. The structure and its problems Traditionally, switching elements such as C-MOS or T
Active matrix type TN-FE incorporating PT
When an M liquid crystal display element is used as a TV image receiving device, the liquid crystal composition thereof is mainly required to meet the following requirements.

(1) High-speed response, (2) Wide field of view, and (3) Good gradation. In order to satisfy these four requirements, a liquid crystal composition is required to have the following physical properties.

(c) Low viscosity. ■) Low refractive index anisotropy. (q) Large ratio of 33/11 in the elastic constant. However, there is still no liquid crystal composition that fully satisfies these physical properties. Not proposed.

Attempts have been made to improve the shortcomings of TN-FEM liquid crystal display elements, such as high visibility and gradation, but the shortcomings in this case are poor responsiveness and increased power consumption, which are not fully satisfactory. At present, it is difficult to obtain the display characteristics of both TV images.

Conventionally, trans-4-n-alkyl- represented by the following formula (wherein n represents 3, 6 or 7) has been used as a liquid crystal compound constituting the liquid crystal composition of an active matrix type TN-FEM liquid crystal display element. (4-cyanophenyl)-cyclohexane.

There is a liquid crystal composition comprising a mixture of such liquid crystal compounds as a typical example of a liquid crystal composition. The physical properties of the above liquid crystal composition are TNI (nematic/isotropic liquid transition temperature) +60°C
TcN (crystallization temperature) -3℃ Δε (dielectric anisotropy) +10.3 Δn (refractive index anisotropy) +〇, 12 η (viscosity) 30cst (20℃).The features of this product are Δε Since Δn is large, the threshold voltage can be lowered, but on the other hand, because Δn is large, the viewing angle is narrow and the TCN is -3°C.
f H7) IA- Still other examples of liquid crystal compounds include a-n-alkyl- represented by the following formula (wherein m represents 2, 3, 4-4, or 7). Trans,trans-dicyclohexyl-4'-carbonitrile is known.

There is a liquid crystal composition comprising a mixture of such liquid crystal compounds as a typical example of a liquid crystal composition. The physical properties of the above liquid crystal composition are as follows: TNI +70°C TcN +14°C Δε +3°9 Δn -1-0,066 (164 cst (20°C)), and the small Δn provides a wide viewing angle. However, it has the drawbacks of high TCN and high η, and is not fully satisfactory.

Another example of a liquid crystal compound is n-alkoxyl 4-trans (4-
Alkylcyclohexyl)-benzene is known.

A liquid crystal composition consisting of a mixture is a typical example of such a liquid crystal composition. The physical property values of the above liquid crystal composition are as follows: TN 1 + 34°C TCN + 14°C Δε −0,3 Δn −1−Q , 09 η 11 cst (201C) This material has a low Δn and a low η. Therefore, the wide field of view and high-speed response are good, but TCN
It has the disadvantage of being as high as +14°C, which narrows the usable temperature range.

An example of another liquid crystal compound is the following formula 7.
Since the temperature range (from 54°C to 312°C) is wide, the addition of this compound has the advantage that the nematic range of the liquid crystal composition can be expanded.

As an example of another liquid crystal compound, 5-n-alkyl-2(4-anophenyl)-1
, 3 dioxane is known. These physical property values are TCN TN
I Δε Δn η20℃r=2 -2℃ -1-67
°C +32-1-0.13 33cstr =3-1
-42℃ +69℃ +32-1-0.13 33cs
tr=4 →-36℃ +43℃ +29 +0.13
35cstr = Ei -1-4s'c +57℃
+32 +0.14 47 cst, and Δε is very large, so the effect of lowering the threshold voltage is expected, but on the other hand, η is high, 33 cst to 47 cst, which is disadvantageous in terms of high-speed response.

As examples of liquid crystal compounds of different sizes, the following formula 7 is known. The physical property values are TNI +160°C TCN + 69°C Δε −1,2 Δn 10.08 η 129 cst (20°C), which indicates that Δn is small and the nematic range is wide. On the other hand, it has the disadvantage of high viscosity.

The above-mentioned known liquid crystal compounds or liquid crystal compositions d: Although each has its advantages, it also has disadvantages, and is not fully satisfactory.

OBJECTS OF THE INVENTION The object of the present invention is to provide a liquid crystal composition which compensates for the drawbacks of the conventionally known liquid crystal compositions as described above and which enables a 1V image with excellent visibility to be obtained in a matrix type TN-FEM liquid crystal display element. Our goal is to provide the following.

In particular, the liquid crystal composition according to the present invention has a low viscosity, low refractive index anisotropy, and a large ratio of 33/11 in the elastic constant. . 4-n-a/l/ki/lateranos, tran'
One type of trill to Sujicyclo to Kinoru four-carbosutrile.”
2. n-alkoxy-4-trans (4-
6- n-alkyl-2-(4-7 anophenyl)-1
, 3 dioxane and the formula 4-n-foHyl) lancecyclohexyl-4
It is characterized by containing -n-fluor-trans, trans-dicyclohexylcarboxylate.

According to the present invention, each of the compounds represented by the above general formulas (1) to (3) is selected, and at least 6 compounds of the above formulas (4), (6) and (6) are further mixed with the mixture thereof. It has been found that a liquid crystal composition comprising the above compounds has excellent properties as shown in the Examples below. That is, the object of the present invention is to provide a liquid crystal composition having even better characteristics by mixing the known liquid crystal compositions as described above.

Description of examples The present invention will be explained below with reference to Examples.

Example 1 A liquid crystal composition was prepared by mixing a liquid crystal composition having the following composition.

6% by weight All the alkyl groups in the above compound are straight chain alkyl groups.

The physical properties of the liquid crystal composition are as follows.

TN162.6°C T CN 20°C or less Δε +9.8 Jn -1-0,082 (T 23cst (20°C)) As can be seen from the physical property values, the liquid crystal composition of this example has T
Since cN is extremely low and both η and Δn are small, high-speed response is achieved at a wide viewing angle.

The figure shows applied voltage versus transmittance characteristics when the above liquid crystal composition is used in a TN-FEM panel, and the γ (v9o%-V10%) value determined from 1 in the figure was 1.24V.

For comparison, 2 in the figure shows Z, a liquid crystal composition manufactured by Merck & Co.
The C broken line which also shows the characteristics of LI-1a00) had a γ of 1.04v.

Effects of the Invention As is clear from the second example, the liquid crystal composition according to the present invention has the following excellent effects.

(1) Low viscosity, which is effective for achieving high-speed response, can be obtained.

(2) Broad perspective! l! A low Δn, which is effective for obtaining f-angle filtering, can be obtained.

(3) A wide threshold characteristic (γ) that is effective in obtaining sufficient gradation and contrast can be obtained.

As described above, the liquid crystal composition according to the present invention has very favorable characteristics for displaying TV images on a matrix type panel equipped with switching elements, and the composition of each substance constituting each liquid crystal composition is By freely changing the ratio, it is possible to further change various properties such as Δn, q, etc. Therefore, the liquid crystal composition of the present invention is very useful as a liquid crystal material for TVs, which is currently in demand.

[Brief explanation of drawings]

The figure is a graph showing applied voltage versus transmittance characteristics of a liquid crystal composition according to the present invention and a conventional liquid crystal composition. 1...Liquid crystal composition according to the present invention, 2...
Conventional liquid crystal composition.

Claims (1)

[Claims] Represented by the general formula (in the formula, n represents 3.cbJ or 7), lutrans-4-n-alkyl-(4-cyanophenyl)-
More than 1m of cyclohegizan, expressed by the general formula (in the formula, m is 2, 3.4 and 7 is represented).
14-n-Furkyl-trans, trans-synchronhexyl-4'-carbonitrile, represented by one or more general formulas (in the formula, p represents 3 or 6, and q represents 2f or 4); Alcoquine-4-trans(4-
one or more types of alkylcyclohexyl)-benzene, and 5-n-alkyl-2-( 4-cyanophenyl)-1,
3 dioxane and formula 4-n-furovirtranscyclohexyl-4-n
- A liquid crystal composition containing phthyl-trans, trans-dicyclohexyl carboxylate.