LC MEDIUM

Abstract

The present invention relates to liquid-crystalline (LC) media and to LC displays (LCDs) containing these media, in particular to LCDs of the twisted nematic (TN) mode, preferably to displays of the LCOS (LC on silicon) mode.

Claims

1. An LC medium with positive dielectric anisotropy, characterised in that it contains one or more compounds of formula I, one or more compounds selected from formulae II and III, and one or more chiral dopants ##STR00381## wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings “alkyl” C.sub.1-6-alkyl, R.sup.a1 H, CH.sub.3 or C.sub.2H.sub.5, i, k 0, 1, 2 or 3, ##STR00382## R.sup.0 an unsubstituted or halogenated alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by —C≡C—, —CF.sub.2O—, —CH═CH—, ##STR00383## —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, or denotes, ##STR00384## X.sup.0 F, Cl, CN, SF.sub.5, SCN, NCS, a halogenated alkyl radical, a halogenated alkenyl radical, a halogenated alkoxy radical or a halogenated alkenyloxy radical having up to 6 C atoms, and Y.sup.0 H or CH.sub.3, Y.sup.1-6 H or F.

2. The LC medium according to claim 1, characterized in that it contains one or more chiral dopants selected from the group consisting of R- or S-1011, R- or S-2011, R- or S-3011, R- or S-4011, and R- or S-5011 ##STR00385##

3. The LC medium according to claim 1, characterized in that it comprises one or more compounds of the formula I selected from the following subformulae ##STR00386## wherein “alkyl” has the meaning given in claim 1.

4. The LC medium according to claim 1, characterized in that it comprises one or more compounds of formula I selected from the group consisting of the following subformulae: ##STR00387##

5. The LC medium according to claim 1, characterized in that it comprises one or more compounds selected from the group consisting of the following subformulae ##STR00388## ##STR00389## in which R.sup.0 and X.sup.0 have the meanings given in claim 1.

6. The LC medium according to claim 1, characterized in that it comprises one or more compounds selected from the group consisting of the following subformulae ##STR00390## ##STR00391## ##STR00392##

7. The LC medium according to claim 1, a characterized in that it additionally comprises one or more compounds selected from the group consisting of the following formulae ##STR00393## in which R.sup.0, X.sup.0 and Y.sup.1-4 have the meanings given in claim 1, Z.sup.0 denotes —C.sub.2H.sub.4—, —(CH.sub.2).sub.4—, —CH═CH—, —CF═CF—, —C.sub.2F.sub.4—, —CH.sub.2CF.sub.2—, —CF.sub.2CH.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —COO— or —OCF.sub.2—, in formulae V and VI also a single bond, in formulae V and VIII also —CF.sub.2O—, r denotes 0 or 1, and s denotes 0 or 1.

8. The LC medium according to claim 1, characterised in that it comprises one or more compounds selected from group consisting of the following formulae ##STR00394## in which R.sup.0 has the meanings given in claim 1.

9. The LC medium according to claim 1, characterised in that it additionally comprises one or more compounds selected from the following formulae: ##STR00395## in which X.sup.0 has the meanings given in claim 1, and “alkyl” denotes C.sub.1-6-alkyl, “alkenyl” and “alkenyl*” denote independently of each other C.sub.2-6-alkenyl, L denotes H or F, R″ denotes C.sub.1-6-alkyl, C.sub.1-6-alkoxy or C.sub.2-6-alkenyl.

10. The LC medium according to claim 1, characterised in that it comprises one or more compounds selected from the following subformulae: ##STR00396## wherein “alkyl” denotes C.sub.1-6-alkyl.

11. The LC medium according to claim 1, characterised in that it comprises one or more compounds of the following formula: ##STR00397## in which R.sup.1 and R.sup.2 independently of each other denote alkyl having 1 to 6 C atoms.

12. The LC medium according to claim 1, characterised in that it additionally comprises one or more compounds selected from the following formulae: ##STR00398## in which R.sup.3 and R.sup.4 each, independently of one another, denote n-alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms, and preferably each, independently of one another, denote alkyl having 1 to 6 C atoms or alkenyl having 2 to 6 C atoms.

13. The LC medium according to claim 1, characterised in that it additionally comprises one or more compounds selected from the following subformulae: ##STR00399## in which “alkyl” denotes C.sub.1-6-alkyl.

14. The LC medium according to claim 1, characterised in that it comprises one or more compounds of the formula XVI ##STR00400## in which R.sup.3 and R.sup.4, each independently of one another, denote n-alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms and L denotes H or F.

15. The LC medium according to claim 1, characterised in that it comprises a compound of formula XVIc2 ##STR00401##

16. The LC medium according to claim 1, characterised in that it comprises one or more compounds of formula IA1 ##STR00402## in which R.sup.0 is ethyl or propyl and X.sup.0 is F.

17. The LC medium according to claim 1, characterised in that it comprises one or more compounds selected from the group consisting of the compounds of the following formulae ##STR00403## in which R.sup.0, X.sup.0 and Y.sup.1-4 each, independently of one another, have one of the meanings given in claim 1.

18. The LC medium according to claim 1, characterised in that it comprises one or more compounds of the formula XXIa ##STR00404## in which R.sup.0 denotes ethyl, n-propyl, n-butyl or n-pentyl.

19. The LC medium according to claim 1, characterised in that it comprises one or more compounds selected from the group of the compounds of the following formulae ##STR00405## in which R.sup.3 denotes n-alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms, and X.sup.0 has the meaning indicated in claim 1.

20. The LC medium according to claim 1, characterised in that it comprises one or more compounds of the formula XXIXa ##STR00406## in which R.sup.3 denotes ethyl, n-propyl, n-butyl or n-pentyl.

21. The LC medium according to claim 1, characterised in that it comprises one or more stabilisers.

22. The LC medium according to claim 1, characterised in that it comprises one or more stabilisers selected from the group consisting of the following formulae ##STR00407## wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings R.sup.a-d straight-chain or branched alkyl with 1 to 10, preferably 1 to 6, very preferably 1 to 4 C atoms, most preferably methyl, X.sup.S H, CH.sub.3, OH or O*, A.sup.S straight-chain, branched or cyclic alkylene with 1 to 20 C atoms which is optionally substituted, n an integer from 1 to 6, preferably 3.

23. The LC medium according to claim 1, characterised in that it comprises one or more stabilisers selected from the group consisting of the following formulae ##STR00408## ##STR00409##

24. A process for the preparation of an LC medium according to claim 4, characterised in that one or more compounds of the formula I or its subformulae are mixed with one or more compounds according to claim 4.

25. (canceled)

26. An LC display containing an LC medium according to claim 1.

27. The LC display according to claim 26, characterized in that it is a TN or TN-TFT display.

28. The LC display according to claim 26, characterized in that it is an LCOS display.

29. The LC display according to claim 26, characterized in that it comprises a silicon-containing backplane (1), a reflective coating (2) in the shape of a pixel array, first (3) and second (4) alignment layers providing planar alignment, a layer (5) of the LC medium, a transparent electrode layer (6), and a transparent substrate (7).

30. The LC display according to claim 26, characterized in that the helical twisting power and amount of the chiral dopant in the LC medium are selected such that the ratio d/p in the display is from 0.015 to 0.2.

Description

EXAMPLE 1

[0290] The LC mixture N1 is formulated as follows:

TABLE-US-00007 APUQU-3-F 9.0% cl.p. 92.6° C. CC-3-V 15.0% Δn 0.1454 CC-3-V1 8.0% Δε + 11.3 CCH-35 7.5% ε.sub.|| 14.8 CPGP-5-2 6.0% γ.sub.1 119 mPa.Math.s CPGP-5-3 5.0% K.sub.1 15.3 CPP-3-F 8.0% K.sub.3 14.9 PCH-301 4.5% V.sub.0 1.23 V PGP-2-3 8.0% PGUQU-3-F 9.5% PP-1-2V1 2.5% PPGU-3-F 0.5% PUQU-3-F 16.5%

[0291] To 99.28% of the mixture N1 are added 0.72% of the chiral dopant S-4011.

EXAMPLE 2

[0292] The LC mixture N2 is formulated as follows:

TABLE-US-00008 APUQU-2-F 6.0% cl.p. 92.8° C. APUQU-3-F 6.0% Δn 0.1119 BCH-32 4.5% Δε 11.5 CC-3-V 33.5% ε.sub.|| 15.0 CC-3-V1 1.0% γ.sub.1 96 mPa.Math.s CCP-V-1 10.0% K.sub.1 13.4 CCP-V2-1 10.0% K.sub.3 16.5 CDUQU-3-F 6.0% V.sub.0 1.14V CPGP-5-2 2.5% PGUQU-3-F 4.0% PGUQU-4-F 4.0% PPGU-3-F 0.5% PUQU-3-F 12.0%

[0293] To 99.75% of the mixture N2 are added 0.22% of the chiral dopant S-4011 and 0.03% of the stabiliser S1-1.

##STR00379##

EXAMPLE 3

[0294] The LC mixture N3 is formulated as follows:

TABLE-US-00009 APUQU-2-F 6.0% cl.p. 92.8° C. APUQU-3-F 6.0% Δn 0.1119 BCH-32 4.5% Δε 11.5 CC-3-V 33.5% ε.sub.|| 15.0 CC-3-V1 1.0% γ.sub.1 96 mPa.Math.s CCP-V-1 10.0% K.sub.1 13.4 CCP-V2-1 10.0% K.sub.3 16.5 CDUQU-3-F 6.0% V.sub.0 1.14 V CPGP-5-2 2.5% PGUQU-3-F 4.0% PGUQU-4-F 4.0% PPGU-3-F 0.5% PUQU-3-F 12.0%

[0295] To 99.888% of the mixture N3 are added 0.04% of the stabiliser S2-1 and 0.108% of the chiral dopant S-4011.

##STR00380##