Liquid-crystal medium

Abstract

The invention relates to a liquid-crystalline medium which comprises at least one compound of the formula I, ##STR00001## in which R.sup.1 and R.sup.1* each, independently of one another, denote an 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 ##STR00002##
in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, A.sup.1 denotes ##STR00003## L.sup.1 denotes F, Cl, CF.sub.3, OCF.sub.3 or CHF.sub.2,
and to the use thereof for electro-optical purposes, in particular for shutter glasses, 3D applications, in TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS and PS-VA-IPS displays.

Claims

1. A liquid-crystalline medium, comprising at least one compound of formula I, ##STR00238## in which R.sup.1 and R.sup.1* each, independently of one another, denote an alkyl or alkoxy radical having 1 to 15 C atoms, in which one or more CH.sub.2 groups are optionally each replaced, independently of one another, by ##STR00239## in such a way that O atoms are not linked directly to one another, and in which optionally one or more H atoms are replaced by halogen, A.sup.1 denotes ##STR00240## L.sup.1 denotes F, Cl, CF.sub.3, OCF.sub.3 or CHF.sub.2.

2. A liquid-crystalline medium, comprising at least one compound of formulae I-1 to I-10, ##STR00241## in which A.sup.1 denotes ##STR00242## L.sup.1 denotes F, Cl, CF.sub.3, OCF.sub.3 or CHF.sub.2, alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms, and alkoxy and alkoxy* each, independently of one another, denote a straight-chain alkoxy radical having 1-6 C atoms.

3. The liquid-crystalline medium according to claim 1, which additionally comprises one or more compounds of formulae II and/or III, ##STR00243## in which R.sup.0 denotes a halogenated or unsubstituted alkyl or alkoxy radical having 1 to 15 C atoms, in which one or more CH.sub.2 groups are optionally each replaced, independently of one another, by ##STR00244## in such a way that O atoms are not linked directly to one another, X.sup.0 denotes 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, Y.sup.1-6 each, independently of one another, denote H, F or Cl, ##STR00245## each, independently of one another, denote ##STR00246##

4. The liquid-crystalline medium according to claim 1, which additionally comprises one or more compounds of formulae IX to XII, ##STR00247## in which X.sup.0 denotes 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, L denotes H or F, alkyl denotes C.sub.1-6-alkyl, R denotes C.sub.1-6-alkyl, C.sub.1-6-alkoxy or C.sub.2-6-alkenyl, and alkenyl and alkenyl* each, independently of one another, denote C.sub.2-6-alkenyl.

5. The liquid-crystalline medium according to claim 1, which additionally comprises one or more compounds of formula XIII, ##STR00248## in which R.sup.1 and R.sup.2 each, independently of one another, denote n-alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms.

6. The liquid-crystalline medium according to claim 1, which additionally comprises one or more compounds of formula XVII, ##STR00249## in which R.sup.1 and R.sup.2 each, independently of one another, denote n-alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 8 C atoms, and L denotes H or F.

7. The liquid-crystalline medium according to claim 1, which additionally comprises one or more compounds of formulae XXVII, XXVIII and/or XXIX, ##STR00250## in which R.sup.0 denotes a halogenated or unsubstituted alkyl or alkoxy radical having 1 to 15 C atoms, in which one or more CH.sub.2 groups are optionally each replaced, independently of one another, by ##STR00251## in such a way that O atoms are not linked directly to one another, and X.sup.0 denotes 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.

8. The liquid-crystalline medium according to claim 1, which additionally comprises one or more compounds of formulae XIX, XX, XXI, XXII, XXIII and/or XXIV, ##STR00252## in which R.sup.0 denotes a halogenated or unsubstituted alkyl or alkoxy radical having 1 to 15 C atoms, in which one or more CH.sub.2 groups are optionally each replaced, independently of one another, by ##STR00253## in such a way that O atoms are not linked directly to one another, X.sup.0 denotes 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.1-4 each, independently of one another, denote H or F.

9. The liquid-crystalline medium according to claim 1, which additionally comprises one or more additive(s) selected from the group consisting of UV stabilisers, dopants and antioxidants.

10. The liquid-crystalline medium according to claim 1, which additionally comprises one or more polymerisable compounds.

11. A process for preparing the liquid-crystalline medium according to claim 1, comprising mixing one or more compounds of formula I with further liquid-crystalline compounds and optionally also with one or more additives and/or at least one polymerisable compound.

12. An electro-optical device, comprising the liquid-crystalline medium according to claim 1.

13. The electro-optical device according to claim 12, which is selected from the group consisting of shutter glasses, 3D applications, TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS and PS-VA-IPS displays.

14. An electro-optical liquid-crystal display containing a liquid-crystalline medium according to claim 1.

15. The liquid-crystalline medium according to claim 1, wherein A.sup.1 denotes ##STR00254##

16. The liquid-crystalline medium according to claim 1, wherein A.sup.1 denotes ##STR00255##

17. The liquid-crystalline medium according to claim 1, wherein A.sup.1 denotes ##STR00256##

18. The liquid-crystalline medium according to claim 2, wherein A.sup.1 denotes ##STR00257##

19. The liquid-crystalline medium according to claim 2, wherein A.sup.1 denotes ##STR00258##

20. The liquid-crystalline medium according to claim 2, wherein A.sup.1 denotes ##STR00259##

Description

EXAMPLES

(1) Above and below, percentage data denote percent by weight. All temperatures are indicated in degrees Celsius. m.p. denotes melting point, cl.p.=clearing point. Furthermore, C=crystalline state, N=nematic phase, S=smectic phase and I=isotropic phase. The data between these symbols represent the transition temperatures.

(2) All physical properties are determined in accordance with Merck Liquid Crystals, Physical Properties of Liquid Crystals, status November 1997, Merck KGaA, Germany, and apply for a temperature of 20 C., unless explicitly indicated otherwise.

Comparative Example V1

(3) TABLE-US-00007 CC-3-V 8.0% Clearing point [ C.]: 102.0 CPGP-5-2 5.0% S>N transition [ C.]: 14.0 CPGP-4-3 5.0% n [589 nm, 20 C.]: 0.1959 CPGP-5-3 5.0% [1 kHz, 20 C.]: 4.8 CP-3-O1 15.0% .sub. [1 kHz, 20 C.]: 8.3 PGIGI-3-F 4.0% .sub. [1 kHz, 20 C.]: 3.5 PGP-2-2V 15.0% PGP-2-3 4.0% LTS bulk [10 C.]: >1000 h PGP-2-4 5.0% LTS bulk [25 C.]: PGP-2-5 10.0% LTS bulk [30 C.]: PGUQU-4-F 4.0% PGUQU-5-F 3.0% PP-1-2V1 7.0% PUQU-3-F 10.0% G-4O-O3

Example M1

(4) TABLE-US-00008 CC-3-V 8.0% Clearing point [ C.]: 105.5 CPGP-5-2 5.0% S>N transition [ C.]: 30.0 CPGP-4-3 6.0% n [589 nm, 20 C.]: 0.2006 CPGP-5-3 5.0% [1 kHz, 20 C.]: 5.3 CP-3-O1 10.0% .sub. [1 kHz, 20 C.]: 9.0 PGIGI-3-F 6.0% .sub. [1 kHz, 20 C.]: 3.7 PGP-2-2V 16.0% PGP-2-3 5.0% LTS bulk [10 C.]: PGP-2-4 5.0% LTS bulk [25 C.]: >1000 h PGP-2-5 10.0% LTS bulk [30 C.]: 888 h PGUQU-4-F 6.0% PGUQU-5-F 3.0% PP-1-2V1 3.0% PUQU-3-F 9.0% G-4O-O3 3.0%

(5) It immediately becomes evident from the comparison of mixtures V1 and M1 (according to the invention) that the addition of small amounts of compound G-4OO3 enables the nematic phase range to be shifted to significantly lower temperatures. At the same time, both the n is increased from 0.1959 to 0.2006 and also the low-temperature stability (LTS bulk) is significantly improved from 10 C. to 30 C.

Example M2

(6) TABLE-US-00009 CC-3-V 38.0% Clearing point [ C.]: 78.0 CCP-V-1 6.0% CCP-3-OT 9.0% n [589 nm, 20 C.]: 0.1066 CPGP-4-3 6.0% [1 kHz, 20 C.]: 9.4 APUQU-2-F 8.0% .sub. [1 kHz, 20 C.]: 13.4 APUQU-3-F 8.5% .sub. [1 kHz, 20 C.]: 4.0 PGUQU-3-F 3.0% PGUQU-4-F 7.0% LTS bulk [20 C.]: >1000 h DPGU-4-F 5.0% LTS bulk [25 C.]: >1000 h CPY-2-O2 1.5% LTS bulk [30 C.]: >1000 h G-4O-O3 8.0%

Example M3

(7) TABLE-US-00010 CC-3-V 44.0% Clearing point [ C.]: 79.0 APUQU-2-F 8.5% APUQU-3-F 8.0% n [589 nm, 20 C.]: 0.1084 CCP-3-OT 6.0% [1 kHz, 20 C.]: 9.6 CCP-V-1 8.0% .sub. [1 kHz, 20 C.]: 13.2 PGUQU-4-F 4.5% .sub. [1 kHz, 20 C.]: 3.5 PGP-2-2V 7.5% DPGU-4-F 5.5% LTS bulk [20 C.]: >1000 h PUQU-3-F 6.5% LTS bulk [25 C.]: >1000 h G-4O-O3 1.5% LTS bulk [30 C.]: 24 h

Example M4

(8) TABLE-US-00011 CC-3-V 25.0% Clearing point [ C.]: 80.0 CC-3-V1 6.0% CC-3-2V1 4.0% n [589 nm, 20 C.]: 0.1108 CCP-V-1 15.0% [1 kHz, 20 C.]: 10.9 CCP-30CF3 3.0% .sub. [1 kHz, 20 C.]: 14.9 APUQU-3-F 4.0% .sub. [1 kHz, 20 C.]: 4.0 CDUQU-3-F 7.0% DGUQU-4-F 5.0% LTS bulk [30 C.]: >744 h DPGU-4-F 5.5% PGP-2-2V 5.0% PGUQU-3-F 6.0% PGUQU-4-F 6.0% PPGU-3-F 0.5% G-4O-O3 8.0%