Liquid-crystalline medium

Abstract

The invention relates to a liquid-crystalline medium comprising at least one compound of the formula I, ##STR00001## in which R.sup.1 and R.sup.2 have the meanings indicated in Claim 1, and to the use thereof in electro-optical liquid-crystal displays.

Claims

1. A liquid-crystalline medium, comprising: at least one compound of the formula I, ##STR00295## in which R denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by CF.sub.2O, ##STR00296## O, COO or OCO in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, R.sup.2 denotes H, an alkyl, or alkoxy radical having 1 to 15 C atoms, where one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by CF.sub.2O, CHCH, ##STR00297## O, COO or OCO in such a way that 0 atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen; and at least two compounds of the formula ##STR00298## wherein R.sup.0 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by CC, CF.sub.2O, CHCH, ##STR00299## O, COO or OCO in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, X.sup.0 denotes F, Cl, a mono- or polyhalogenated alkyl or alkoxy radical having 1 to 6 C atoms, a mono- or polyhalogenated alkenyl or alkenyloxy radical having 2 to 6 C atoms, Y.sup.1-6 each, independently of one another, denote H or F, Z.sup.0 denotes C.sub.2H.sub.4, (CH.sub.2).sub.4, CHCH, CFCF, C.sub.2F.sub.4, CH.sub.2CF.sub.2, CF.sub.2CH.sub.2, CH.sub.2O, OCH.sub.2, COO, CF.sub.2O, OCF.sub.2, or a single bond, and r denotes 0 or 1, and ##STR00300## denotes ##STR00301## or at least one compound of formula I and at least one compound selected from the group consisting of compounds of formulas XIIa, XIIb, XIIc, IIIa, and IIIb, ##STR00302## or at least one compound of formula I and at least one compound of the formula XI and at least one compound selected from the group consisting of compounds of formulas XIIa, XIIb, XIIc, IIIa, and IIIb, wherein R.sup.1 and R.sup.2 each, independently of one another, denote alkyl, alkenyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyloxy, each having up to 9 C atoms, and preferably each, independently of one another, denote alkyl having 1 to 8 C atoms, and wherein R.sup.3a and R.sup.4a each, independently of one another, denote H, CH.sub.3, C.sub.2H.sub.5 or C.sub.3H.sub.7, and alkyl denotes a straight-chain alkyl group having 1 to 8 C atoms.

2. The liquid-crystalline medium of claim 1, comprising at least one compound selected from the group consisting of the compounds of the formulae I-1 to I-12 ##STR00303## ##STR00304##

3. The liquid-crystalline medium of claim 1, additionally comprising one or more compounds of the formulae II and/or III, ##STR00305## in which ring A denotes 1,4-phenylene or trans-1,4-cyclohexylene, a denotes 0 or 1, R.sup.3 denotes alkenyl having 2 to 9 C atoms, and R.sup.4 denotes 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 CC, CF.sub.2O, ##STR00306## O, COO or OCO 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.

4. The liquid-crystalline medium of claim 1, additionally comprising one or more compounds selected from the group consisting of, ##STR00307## ##STR00308## wherein R.sup.3a and R.sup.4a each, independently of one another, denote H, CH.sub.3, C.sub.2H.sub.5 or C.sub.3H.sub.7, and alkyl denotes a straight-chain alkyl group having 1 to 8 C atoms.

5. The liquid-crystalline medium of claim 1, additionally comprising one or more compounds selected from the group consisting of compounds of the following formulas, ##STR00309## wherein R.sup.0 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by CC, CF.sub.2O, CHCH, ##STR00310## O, COO or OCO in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, X.sup.0 denotes F, Cl, a mono- or polyhalogenated alkyl or alkoxy radical having 1 to 6 C atoms, a mono- or polyhalogenated alkenyl or alkenyloxy radical having 2 to 6 C atoms, Y.sup.1-6 each, independently of one another, denote H or F, Z.sup.0 denotes C.sub.2H.sub.4, (CH.sub.2).sub.4, CHCH, CFCF, C.sub.2F.sub.4, CH.sub.2CF.sub.2, CF.sub.2CH.sub.2, CH.sub.2O, OCH.sub.2, COO, CF.sub.2O, or OCF.sub.2, or in the formulae V also a single bond, and r denotes 0 or 1.

6. The liquid-crystalline medium of claim 5, comprising one or more compounds selected from the group consisting of compounds of the following formulae, ##STR00311## wherein R.sup.0 denotes 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 CC, CF.sub.2O, CHCH, ##STR00312## O, COO or OCO 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, X.sup.0 denotes F, Cl, a mono- or polyhalogenated alkyl or alkoxy radical having 1 to 6 C atoms, a mono- or polyhalogenated alkenyl or alkenyloxy radical having 2 to 6 C atoms.

7. The liquid-crystalline medium of claim 1, additionally comprising one or more compounds selected from the compounds of the formula X, ##STR00313## wherein R.sup.0 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by CC, CF.sub.2O, CHCH, ##STR00314## O, COO or OCO in such a way that 0 atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, X.sup.0 denotes F, Cl, a mono- or polyfluorinated alkyl or alkoxy radical having 1 to 6 C atoms, a mono- or polyfluorinated alkenyl or alkenyloxy radical having 2 to 6 C atoms, Y.sup.1-2 each, independently of one another, denote H or F, and ##STR00315## each, independently of one another, denote ##STR00316##

8. The liquid-crystalline medium of claim 1, additionally comprising one or more compounds selected from the group consisting of, ##STR00317## wherein R.sup.1 and R.sup.2 each, independently of one another, denote alkyl, alkenyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyloxy, each having up to 9 C atoms.

9. The liquid-crystalline medium of claim 1, additionally comprising one or more compounds selected from the group consisting of compounds of the following formulae, ##STR00318## wherein R.sup.0 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by CC, CF.sub.2O, CHCH, ##STR00319## O, COO or OCO in such a way that 0 atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, X.sup.0 denotes F, Cl, a mono- or polyfluorinated alkyl or alkoxy radical having 1 to 6 C atoms, a mono- or polyfluorinated alkenyl or alkenyloxy radical having 2 to 6 C atoms, Y.sup.1-2 each, independently of one another, denote H or F.

10. The liquid-crystalline medium of claim 1, additionally comprising one or more compounds selected from the group consisting of compounds of the following formulae, ##STR00320## wherein R.sup.0 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by CC, CF.sub.2O, CHCH, ##STR00321## O, COO or OCO in such a way that O atoms are not linked directly to one another, and in which, one or more H atoms may be replaced by halogen, X.sup.0 denotes F, Cl, a mono- or polyfluorinated alkyl or alkoxy radical having 1 to 6 C atoms, a mono- or polyfluorinated alkenyl or alkenyloxy radical having 2 to 6 C atoms, Y.sup.1-2 each, independently of one another, denote H or F.

11. The liquid-crystalline medium of claim 1, wherein the liquid-crystalline medium comprises 1-30% by weight of one or more compounds of the formula I.

12. The liquid-crystalline medium of claim 1, additionally comprising one or more UV stabilisers and/or antioxidants.

13. The liquid-crystalline medium of claim 1, additionally comprising one or more reactive mesogens (RMs).

14. A process for the preparation of a liquid-crystalline medium according to claim 1, comprising mixing one or more compounds of the formula I and at least two compounds of the formula XI, or at least one compound of formula I and at least one compound selected from the group consisting of compounds of formulas XIIa, XIIb, XIIc, IIIa, and IIIb, or at least one compound of formula I and at least one compound of the formula XI and at least one compound selected from the group consisting of compounds of formulas XIIa, XIIb, XIIc, IIIa, and IIIb with at least one further mesogenic compound and optionally with at least one RM and/or one or more additive(s).

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

16. A TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, or PS-FFS display, shutter spectacle for 3D effect, an LC lense or a positive VA display, containing a liquid-crystalline medium according to claim 1.

17. The liquid-crystalline medium according to claim 1 additionally comprising at least one stabilizer selected from the group consisting of the following compounds: ##STR00322## ##STR00323## ##STR00324## ##STR00325## ##STR00326##

18. The liquid-crystalline medium claim 1 additionally comprising at least one reactive mesogen selected from the group consisting of the following compounds: ##STR00327## ##STR00328## ##STR00329## ##STR00330## ##STR00331## ##STR00332## ##STR00333## ##STR00334## ##STR00335## ##STR00336##

Description

EXAMPLES

(1) The following working examples are intended to explain the invention without restricting it.

(2) 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. Furthermore,

(3) TABLE-US-00007 V.sub.o denotes threshold Voltage, capacitive [V] at 20 C. n denotes the optical anisotropy measured at 20 C. and 589 nm denotes the dielectric anisotropy at 20 C. and 1 kHz cp. denotes clearing point [ C.] K.sub.1 denotes elastic constant, splay deformation at 20 C., [pN] K.sub.3 denotes elastic constant, bend deformation at 20 C., [pN] .sub.1 denotes rotational viscosity measured at 20 C. [mPa .Math. s], determined by the rotation method in a magnetic field LTS denotes low-temperature stability (nematic phase), determined in test cells.

(4) The compounds mentioned below are prepared as described in WO95/30723:

(5) ##STR00294##

Mixture Examples

(6) The electro-optical data are measured in a TN cell at the 1st minimum (i.e. at a d.Math.n value of 0.5 m) at 20 C., unless expressly indicated otherwise. The optical data are measured at 20 C., unless expressly indicated otherwise. All physical properties are determined in accordance with Merck Liquid Crystals, Physical Properties of Liquid Crystals Status November 1997, Merck KGaA, Germany, and apply to a temperature of 20 C., unless explicitly indicated otherwise.

Example M1

(7) TABLE-US-00008 APUQU-2-F 4.00% Clearing point [ C.]: 80 APUQU-3-F 4.00% n [589 nm, 20 C.] 0.1107 CC-3-V 46.00% [kHz, 20 C.]: +10.4 CCP-V-1 4.00% .sub.1 [mPa .Math. s, 20 C.]: 69 PGP-2-2V 5.00% K.sub.1 [20 C.]: 12.0 PGUQU-3-F 6.00% K.sub.3 [20 C.]: 14.1 PGUQU-4-F 8.00% V.sub.0 [V]: 1.13 PGUQU-5-F 6.00% LTS bulk 25 C.: >1000 h PUQU-3-F 8.00% CCP-3OCF.sub.3 4.00% CCVC-3-V 5.00%

Example M2

(8) TABLE-US-00009 APUQU-3-F 4.50% Clearing point [ C.]: 79.5 CC-3-V 46.00% n [589 nm, 20 C.] 0.1101 CCP-V-1 4.00% [kHz, 20 C.]: +10.2 PGP-2-2V 5.00% .sub.1 [mPa .Math. s, 20 C.]: 67 PGUQU-3-F 5.00% K.sub.1 [20 C.]: 12.2 PGUQU-4-F 6.00% K.sub.3 [20 C.]: 13.5 PGUQU-5-F 5.00% V.sub.0 [V]: 1.15 PUQU-3-F 11.50% LTS bulk 25 C.: >1000 h CCP-3OCF.sub.3 4.00% CCVC-3-V 5.00% DPGU-4-F 4.00%

Example M3

(9) TABLE-US-00010 CC-3-V 44.00% Clearing point [ C.]: 79 PGP-2-2V 13.00% n [589 nm, 20 C.] 0.1158 CCP-V-1 6.00% [kHz, 20 C.]: +7.6 CCP-3OCF.sub.3 3.00% .sub.1 [mPa .Math. s, 20 C.]: 62 PUQU-3-F 13.00% K.sub.1 [pN, 20 C.]: 12.3 APUQU-3-F 6.00% K.sub.3 [pN, 20 C.]: 13.8 PGUQU-4-F 5.00% V.sub.0 [V]: 1.32 PGUQU-3-F 5.00% CCVC-3-V 5.00%

Example M4

(10) TABLE-US-00011 CC-3-V 46.00% Clearing point [ C.]: 79 PGP-2-2V 6.00% n [589 nm, 20 C.] 0.1021 CCP-V-1 6.00% [kHz, 20 C.]: +7.8 CCP-3OCF.sub.3 8.00% .sub.1 [mPa .Math. s, 20 C.]: 58 PUQU-3-F 15.00% K.sub.1 [pN, 20 C.]: 12.2 APUQU-3-F 4.00% K.sub.3 [pN, 20 C.]: 13.8 PGUQU-4-F 2.00% V.sub.0 [V]: 1.32 PGUQU-3-F 3.00% CCVC-3-V 5.00% DPGU-4-F 5.00%

Example M5

(11) TABLE-US-00012 CC-3-V 30.00% Clearing point [ C.]: 91.5 CC-3-V1 8.00% n [589 nm, 20 C.] 0.1088 CC-3-2V1 10.00% [kHz, 20 C.]: +15.9 CCP-3OCF.sub.3 4.00% .sub.1 [mPa .Math. s, 20 C.]: 95 CCVC-3-V 5.00% K.sub.1 [pN, 20 C.]: 14.9 PUQU-3-F 5.50% K.sub.3 [pN, 20 C.]: 15.9 APUQU-2-F 4.50% V.sub.0 [V]: 1.02 APUQU-3-F 6.00% LTS bulk 20 C.: >1000 h PGUQU-3-F 7.00% PGUQU-4-F 5.00% DPGU-4-F 7.00% DGUQU-4-F 8.00%

Example M6

(12) TABLE-US-00013 CC-3-V 28.50% Clearing point [ C.]: 91.5 CC-3-V1 10.00% n [589 nm, 20 C.] 0.1192 CC-3-2V1 11.00% [kHz, 20 C.]: +4.4 CCP-V-1 4.50% .sub.1 [mPa .Math. s, 20 C.]: 69 PP-1-2V1 6.00% K.sub.1 [pN, 20 C.]: 17.0 PGP-2-2V 16.00% K.sub.3 [pN, 20 C.]: 16.9 CCP-3OCF.sub.3 5.00% V.sub.0 [V]: 2.08 DGUQU-4-F 5.00% PGUQU-4-F 5.00% PGUQU-5-F 4.00% CCVC-3-V 5.00%

Example M7

(13) TABLE-US-00014 CC-3-V 30.00% Clearing point [ C.]: 104 CC-3-V1 8.00% n [589 nm, 20 C.] 0.1196 PCH-301 3.00% [kHz, 20 C.]: +3.4 CCP-3OCF.sub.3 6.00% .sub.1 [mPa .Math. s, 20 C.]: 78 CCP-5OCF.sub.3 5.00% K.sub.1 [pN, 20 C.]: 16.9 CCP-V-1 4.00% K.sub.3 [pN, 20 C.]: 17.5 CCP-V2-1 8.00% V.sub.0 [V]: 2.38 PGP-1-2V 6.00% LTS bulk 30 C.: >1000 h PGP-2-2V 8.00% PGP-3-2V 3.00% PUQU-3-F 8.00% CPGP-4-3 3.00% DPGU-4-F 3.00% CCVC-3-V 5.00%