JPH1053771A - Nematic liquid crystal composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nematic liq. crystal compsn. having a low driving voltage, a high contrast, an excellent light resistance, a high distinctness, and an esp. wide working temp. range by using a liq. crystal compd. having high birefringence and clear point (85-110 deg.C) in combination with a suitable resin. SOLUTION: This compsn. contains 5-20wt.% cyano compd. represented by formula I(wherein R<1> is 1-5C linear alokxy; and L is H or F), 25-50wt.% chlorine compd. reprinted by formula II(wherein R<2> is 1-5C linear alkyl), 5-20wt.% chlorine compd. represented by formula III(wherein R<3> is 1-5C linear alkyl; and L is H or F), 20-40wt.% fluorine compd. represented by formula IV(wherein R<4> is 1-5C linear alkyl; and each L is independently H or F), and 5-20wt.% fluorine compd. represented by formula V(wherein R<5> is 1-5C linear alkyl). The total amt. of these five compds. contained in 80wt.% or higher, pref. 95-100wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a nematic liquid crystal composition, and more particularly to a nematic liquid crystal composition for a polymer dispersed liquid crystal display device, and more particularly to an external voltage for controlling light scattering at an interface between a liquid crystal and a polymer. The present invention relates to a nematic liquid crystal composition for use as a liquid crystal display component applied to a display mode by changing the refractive index difference between a liquid crystal (or a continuous liquid crystal network) and a polymer by using a liquid crystal display component. It can be used for flat display devices, projection televisions or personal computers, laptops or palmtops, signboards, windows, doors or walls where shuttering effects are applied, in particular addressed by MIM diode arrays The present invention relates to a nematic liquid crystal composition applicable to a display device.

[0002]

2. Description of the Related Art Generally, a TN or STN type display device to be practically used requires polarization and orientation means. In order to avoid these defects, it has been suggested to use the refractive index of the liquid crystal material to electrically control the transmittance and the opacity state (for example, JP58-5).
01631-A, JP59-226322-A, JP6
1-502128-A). The liquid crystal material used for such a polymer dispersed display basically consists of a rod-shaped compound containing a terminal cyano group. Recently, in order to improve the performance of such polymer dispersed displays,
It has been proposed to combine certain chloro-compounds with 3-fluorobenzonitrile compounds of the formula:

[0003]

Embedded image Wherein ring A is 1,4-phenylene or trans-1,
4-cyclohexylene (JP7-238285-)
A). However, such compositions exhibit a clearing point below 85 ° C. Clearing points are very important in the production of polymer dispersed liquid crystal display devices.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to address the most important requirements for liquid crystal display devices of the polymer type, namely low drive voltage, high contrast, excellent lightfastness and high definition, especially at 85 ° C. or higher. It is an object of the present invention to provide a novel liquid crystal composition which meets all requirements such as a wide operating temperature range requiring a clearing point.

[0005]

SUMMARY OF THE INVENTION In combination with a suitable resin material, a large birefringence (Δn ≧ 0.200) and 85 ° C.
The object of the present invention can be solved by using a liquid crystal composition having a clearing point of ~ 110 ° C. Accordingly, the present invention relates to a nematic liquid crystal composition, wherein the composition comprises 5 to 20% by weight, preferably 7.5 to 15% by weight, of at least one cyano-compound from Group 1 below:

Embedded image Wherein R ¹ is a linear alkoxy group having 1 to 5 carbon atoms and L is H or F;

At least one chloro-compound from group 2 below is present in an amount of 25-50% by weight, preferably 30-4% by weight.
0% by weight:

Embedded image Wherein R ² is a linear alkyl group having 1 to 5 carbon atoms; and

5 to 20% by weight, preferably 7.5 to 1% by weight of at least one chloro-compound from group 3
5% by weight:

Embedded image Wherein L is H or F and R ³ is carbon atom 1
A nematic liquid crystal composition containing up to 5 linear alkyl groups;

The liquid crystal compounds of Groups 2 and 3 are particularly excellent in chemical stability. The higher the content of these compounds, the more stable the liquid crystal composition.
However, if the composition consists solely of Group 2 and Group 3 compounds, its dielectric anisotropy will be smaller and thus its threshold voltage will be higher. As a result, the resulting display device requires a higher drive voltage. In a preferred embodiment, the composition according to the present invention comprises at least one fluoro-
The compound contains 20 to 40% by weight, especially 25 to 35% by weight:

[0009]

Embedded image Wherein R ⁴ is a linear alkyl group having 1 to 5 carbon atoms, and L ¹ and L ² are each independently H 2
Or F. In another preferred embodiment, a composition according to the present invention comprises a compound of group 4 comprising at least one compound wherein L ¹ and L ² are H and at least one compound wherein L ¹ and L ² are F. It contains.
In another preferred embodiment, the composition according to the invention contains from 5 to 20% by weight, in particular from 7.5 to 15% by weight, of at least one fluoro-compound from group 5:

[0010]

Embedded image Wherein, R ⁵ is a straight-chain alkyl group having 1 to 5 carbon atoms.

The compounds of groups 1, 2, 3, 4 and 5 are present in an amount of at least up to 80% by weight, in particular from 95 to 10%.
It is added in an amount of 0% by weight. If the composition according to the invention contains other components in amounts of up to 20% by weight, these components are added for adjusting the birefringence or the dielectric anisotropy. These additional components are generally selected from the group of mesogenic compounds consisting of cyanobiphenyl compounds, cyanoterphenyl compounds, cyclohexylbenzonitrile compounds, dialkyltolan compounds, alkylalkoxytolan compounds and cyclohexyltolan compounds. When the nematic liquid crystal composition is used for a polymer-dispersed liquid crystal display device, there is no particular limitation on the method of using the compound and the method of manufacturing the device. Known techniques, for example, a method of introducing a liquid crystal composition into a polymer capsule, a method of mixing the composition and a photocurable or thermosetting material, and then phase-separating to form a droplet liquid crystal, or a polymer and composition A method of dissolving both of the compounds in a solvent and removing the solvent from the mixture of the polymer and the composition can be used.

[0012]

The present invention will be described with reference to the following specific examples. However, the scope of the present invention is not limited by this specific example. Example 1 A nematic liquid crystal composition as shown in Table 1 is produced. This composition has the following physical properties: Clearing point (° C.): +99 Birefringence: 0.2278 Dielectric anisotropy: 11.9 Threshold voltage (Vth): 2.13 V

This composition is added to a resin mixture of oligomers obtained from 2-ethylhexyl acrylate, neopentyl glycol diacrylate and urethane acrylate. Photoinitiator [Ciba Geig
Irgacure (Irg) from y, Basle, Switzerland
acure) 184], and then the composition is filled into a cell formed from two ITO plates and then irradiated with UV at 365 nm and an intensity of 30 mW / cm ² at room temperature for 5 minutes.

Table 1:

Embedded image

Continuation of front page (71) Applicant 591032596 Frankfurter Str. 250, D-64293 Darmstadt, Federal Republic of Germany (72) Inventor Shuhei Yamada Germany Day-64293 Darmstadt Frankfurter Strasse 250 (72) Inventor Hidekaz Kobayashi Germany-64293 Darm Stadt Frankfurter Straße 250 (72) Inventor Hiroshi Numata Germany D-64293 Darm Stadt Frankfurter Straße 250 (72) Inventor Yukiomi Tanaka Germany D-64293 Darm Stadt Frankfurter Straße 250

Claims (4)

[Claims] 1 to 5% by weight of at least one cyano compound from the following group 1: Wherein R ¹ is a linear alkoxy group having 1 to 5 carbon atoms, and L is H or F; at least one chloro-compound from group 2
% By weight: Wherein R ² is a linear alkyl group having 1 to 5 carbon atoms; and 5 to 20% by weight of at least one chloro-compound from group 3 below: Wherein L is H or F and R ³ is carbon atom 1
A nematic liquid crystal composition containing up to 5 linear alkyl groups; (2) at least one kind of a member from the following group 4:
20 to 40% by weight of the fluoro compound:Where R^Four Is a linear alkyl having 1 to 5 carbon atoms
And L¹And L^TwoAre each independently H
Or nematic, according to claim 1, containing
Liquid crystal composition. 3. Compounds from group 4 comprising at least one compound wherein L ¹ and L ² are H and at least one compound wherein L ¹ and L ² are F. 3. The nematic liquid crystal composition according to item 1. 4. An amount of at least one fluoro-compound from group 5 below of 5-20% by weight: Wherein, R ⁵ is a straight-chain alkyl group having 1 to 5 carbon atoms, containing a nematic liquid crystal composition according to any one of claims 1 to 3.