Liquid-crystal medium

Abstract

The present invention relates to a liquid-crystalline medium (LC medium), to the use thereof for electro-optical purposes, and to LC displays containing this medium.

Claims

1. An LC medium, having positive dielectric anisotropy and comprising one or more compounds of formula IA and one or more compounds of formula IB ##STR00425## in which R.sup.1 and R.sup.2 in each case, independently of one another, denote alkyl, alkoxy, oxaalkyl or fluoroalkyl, in each case having 1 to 7 C atoms, the LC medium comprises no compounds of the formulae IA and IB in which one or both radicals R.sup.1 or R.sup.2 contain a CC double bond, and wherein of the one or more compounds of formula IA at least one of formula IA1a and/or formula IA1b is present ##STR00426## and of the one or more compounds of formula IB at least a compound of formula IB1a is present ##STR00427## and wherein said medium further comprises one or more compounds selected from formulae XVIb1, XVIb2, and XVIb3 ##STR00428##

2. The LC medium according to claim 1, wherein the one or more compounds of the formula IA are of the following sub-formulae ##STR00429## in which the individual radicals, in each case independently of one another and identically or differently on each occurrence, have the following meaning alkyl, alkyl* straight-chain alkyl having 1-6 C atoms, and alkoxy straight-chain alkoxy having 1-6 C atoms.

3. The LC medium according to claim 2, wherein the one or more compounds of the formula IB are of the following sub-formula ##STR00430## in which alkyl is a straight-chain alkyl having 1-6 C atoms, and alkoxy is a straight-chain alkoxy having 1-6 C atoms.

4. The LC medium according to claim 1, further comprising one or more compounds of the following sub-formulae ##STR00431##

5. The LC medium according to claim 1, further comprising one or more compounds of formulae II and III ##STR00432## in which the individual radicals, in each case independently of one another and identically or differently on each occurrence, have the following meaning ##STR00433## R.sup.0 unsubstituted or halogenated alkyl or alkoxy having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may in each case be replaced, independently of one another, by CF.sub.2O, ##STR00434## O, COO, or OCO in such a way that O atoms are not linked directly to one another, X.sup.0 F, Cl, halogenated alkyl, halogenated alkoxy or halogenated alkenyloxy, in each case having up to 6 C atoms, Y.sup.1-6 H or F, and Y.sup.0 H or CH.sub.3.

6. The LC medium according to claim 1, additionally comprising one or more compounds of formulae IV, V, VI, VII, and VIII ##STR00435## in which R.sup.0 unsubstituted or halogenated alkyl or alkoxy having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may in each case be replaced, independently of one another, by CF.sub.2O, ##STR00436## O, COOor OCO in such a way that O atoms are not linked directly to one another, X.sup.0 F, Cl, halogenated alkyl, halogenated alkoxy or halogenated alkenyloxy, in each case having up to 6 C atoms, Y.sup.1-4 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 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.

7. The LC medium according to claim 5, further comprising one or more compounds of the following formula ##STR00437## in which R.sup.0 unsubstituted or halogenated alkyl or alkoxy having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may in each case be replaced, independently of one another, by CF.sub.2O, ##STR00438## O, COOor OCOin such a way that O atoms are not linked directly to one another, X.sup.0 F, Cl, halogenated alkyl, halogenated alkoxy or halogenated alkenyloxy, in each case having up to 6 C atoms, and Y.sup.1-4 H or F.

8. The LC medium according to claim 5, further comprising one or more compounds of the following formula ##STR00439## in which R.sup.0 unsubstituted or halogenated alkyl or alkoxy having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may in each case be replaced, independently of one another, by CF.sub.2O, ##STR00440## O, COOor OCOin such a way that O atoms are not linked directly to one another, X.sup.0 F, Cl, halogenated alkyl, halogenated alkoxy or halogenated alkenyloxy, in each case having up to 6 C atoms, and y.sup.1-2 H or F.

9. The LC medium according to claim 5, further comprising one or more compounds of the following formula ##STR00441## in which R.sup.0 unsubstituted or halogenated alkyl or alkoxy having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may in each case be replaced, independently of one another, by CF.sub.2O, ##STR00442## O, COOor OCOin such a way that O atoms are not linked directly to one another, and Y.sup.2-4 H or F.

10. The LC medium according to claim 1, further comprising one or more compounds of the following formulae ##STR00443## in which R.sup.1 and R.sup.2 in each case, independently of one another, denote alkyl, alkoxy, oxaalkyl or fluoroalkyl, in each case having 1 to 7 C atoms, and L denotes H or F.

11. The LC medium according to claim 10, further comprising one or more compounds of the following formulae ##STR00444## in which R.sup.1 and R.sup.2 n each case, independently of one another, denote alkyl, alkoxy, oxaalkyl or fluoroalkyl, in each case having 1 to 7 C atoms, and L denotes H or F.

12. The LC medium according to claim 5, further comprising one or more compounds of the following formulae ##STR00445## in which R.sup.0 unsubstituted or halogenated alkyl or alkoxy having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may in each case be replaced, independently of one another, by CF.sub.2O, ##STR00446## O, COOor OCO in such a way that O atoms are not linked directly to one another, X.sup.0 F, Cl, halogenated alkyl, halogenated alkoxy or halogenated alkenyloxy, in each case having up to 6 C atoms, and Y.sup.1-4 H or F.

13. The LC medium according to claim 1, further comprising one or more stabilizers of the following formulae ##STR00447## in which the individual radicals, in each case independently of one another and identically or differently on each occurrence, have the following meaning R.sup.a-d C.sub.1-20-straight-chain or C.sub.3-10-branched alkyl, X.sup.s H, CH.sub.3, OH or O*, A.sup.s C.sub.1-20-straight-chain, C.sub.3-20-branched or C.sub.3-20-cyclic alkylene, which is optionally substituted, and n an integer from 1 to 6.

14. The LC medium according to claim 1 having no compounds which contain a CC double bond, except for a CC double bond as constituent of a polymerizable group or of an aromatic or unsaturated ring.

15. A process for the preparation of an LC medium according to claim 1, comprising mixing together one or more compounds of the formula IA1a or IA1b and IB1a, and optionally one or more additional compounds of formula IA and one or more additional compounds of the formula IB.

16. An electro-optical device, comprising an LC medium according to claim 1.

17. A product, which is one of TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS, positive-VA or PS-positive-VA displays, or LC windows or shutter spectacles for 3D applications, comprising an LC medium according to claim 1.

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

19. An LC display according to claim 18, that is a TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS, positive-VA or PS-positive-VA display.

20. The LC medium according to claim 2, wherein alkyl and alkyl* are, each independently, ethyl, propyl, butyl or pentyl, and alkoxy is methoxy, ethoxy or propoxy.

21. The LC medium according to claim 3, wherein alkyl is ethyl, propyl, butyl or pentyl, and alkoxy is methoxy, ethoxy or propoxy.

22. The LC medium according to claim 1, wherein the LC medium contains 2-30% of one or more compounds selected from formulae XVIb1, XVIb2 and XVIb3.

23. The LC medium according to claim 1, wherein the LC medium contains two or more compounds selected from formulae XVIb1, XVIb2 and XVIb3.

24. An LC medium, having positive dielectric anisotropy and comprising: one or more compounds of formula IA and one or more compounds of formula IB ##STR00448## in which R.sup.1 and R.sup.2 n each case, independently of one another, denote alkyl, alkoxy, oxaalkyl or fluoroalkyl, in each case having 1 to 7 C atoms, wherein the LC medium comprises no compounds of the formulae IA and IB in which one or both radicals R.sup.1 or R.sup.2 contain a CC double bond and wherein of the one or more compounds of formula IA at least one of formula IA1a and/or formula IA1b is present ##STR00449## and of the one or more compounds of formula IB at least a compound of formula IB1a is present ##STR00450## one or more compounds of formulae II and III ##STR00451## in which the individual radicals, in each case independently of one another and identically or differently on each occurrence, have the following meaning ##STR00452## R.sup.0 unsubstituted or halogenated alkyl or alkoxy having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may in each case be replaced, independently of one another, by CF.sub.2O, ##STR00453## O, COOor OCO in such a way that O atoms are not linked directly to one another, X.sup.0 F, Cl, halogenated alkyl, halogenated alkoxy or halogenated alkenyloxy, in each case having up to 6 C atoms, Y.sup.1-6 H or F, and Y.sup.0 H or CH.sub.3; and one or more compounds of formula X ##STR00454## in which R.sup.0 unsubstituted or halogenated alkyl or alkoxy having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may in each case be replaced, independently of one another, by CF.sub.2O, ##STR00455## O, COOor OCO in such a way that O atoms are not linked directly to one another, X.sup.0 F, Cl, halogenated alkyl, halogenated alkoxy or halogenated alkenyloxy, in each case having up to 6 C atoms, and Y.sup.1-4 H or F.

25. An LC medium, having positive dielectric anisotropy and comprising: one or more compounds of formula IA and one or more compounds of formula IB ##STR00456## in which R.sup.1 and R.sup.2 n each case, independently of one another, denote alkyl, alkoxy, oxaalkyl or fluoroalkyl, in each case having 1 to 7 C atoms, wherein the LC medium comprises no compounds of the formulae IA and IB in which one or both radicals R.sup.1 or R.sup.2 contain a CC double bond and wherein of the one or more compounds of formula IA at least one of formula IA1a and/or formula IA1b is present ##STR00457## and of the one or more compounds of formula IB at least a compound of formula IB1a is present ##STR00458## one or more compounds of formulae II and III ##STR00459## in which the individual radicals, in each case independently of one another and identically or differently on each occurrence, have the following meaning ##STR00460## R.sup.0 unsubstituted or halogenated alkyl or alkoxy having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may in each case be replaced, independently of one another, by CF.sub.2O, ##STR00461## O, COOor OCO in such a way that O atoms are not linked directly to one another, X.sup.0 F, Cl, halogenated alkyl, halogenated alkoxy or halogenated alkenyloxy, in each case having up to 6 C atoms, Y.sup.1-6 H or F, and Y.sup.0 H or CH.sub.3; and one or more compounds of formula XI ##STR00462## in which R.sup.0 unsubstituted or halogenated alkyl or alkoxy having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may in each case be replaced, independently of one another, by CF.sub.2O, ##STR00463## O, COOor OCO in such a way that O atoms are not linked directly to one another, and Y.sup.2-4 H or F.

26. An LC medium, having positive dielectric anisotropy and comprising: one or more compounds of formula IA and one or more compounds of formula IB ##STR00464## in which R.sup.1 and R.sup.2 n each case, independently of one another, denote alkyl, alkoxy, oxaalkyl or fluoroalkyl, in each case having 1 to 7 C atoms, wherein the LC medium comprises no compounds of the formulae IA and IB in which one or both radicals R.sup.1 or R.sup.2 contain a CC double bond and wherein of the one or more compounds of formula IA at least one of formula IA1a and/or formula IA1b is present ##STR00465## and of the one or more compounds of formula IB at least a compound of formula IB1a is present ##STR00466## and one or more stabilizers of the following formulae ##STR00467## in which the individual radicals, in each case independently of one another and identically or differently on each occurrence, have the following meaning R.sup.a-d C.sub.1-10-straight-chain or C.sub.3-10-branched alkyl, X.sup.s H, CH.sub.3, OH or O*, A.sup.s C.sub.1-20-straight-chain, C.sub.3-20-branched or C.sub.3-20-cyclic alkylene, which is optionally substituted, and n an integer from 1 to 6.

Description

COMPARATIVE EXAMPLE 1

(1) TABLE-US-00008 CC-3-V 29.4% cl.p. 75.5 C. CCP-V-1 20.2% n 0.1035 CCP-V2-1 9.0% +7.1 CPP-2-F 4.1% .sub. 10.4 CPP-3-F 4.0% .sub. 4.3 BCH-3F.F.F 10.0% .sub.1 61 mPas PUQU-3-F 23.3% V.sub.10 1.53 V LTS 1000 h

EXAMPLE 1

(2) TABLE-US-00009 PUQU-3-F 8.5% cl.p. 72.5 C. CCQU-2-F 12.0% n 0.0985 CCQU-3-F 13.0% +7.2 CCQU-5-F 10.0% .sub. 10.6 CCGU-3-F 8.0% .sub. 3.4 PCH-301 10.5% .sub.1 84 mPas PCH-3CL 3.0% V.sub.10 1.50 V CCH-23 14.0% LTS 1000 h CCH-34 8.0% PGP-2-3 4.0% PGP-2-4 4.0% PGP-2-5 5.0%

EXAMPLE 2

(3) TABLE-US-00010 CCH-23 16.0% cl.p. 74.5 C. CCH-34 7.0% n 0.0989 PCH-301 17.0% +6.5 CCH-301 8.0% .sub.|| 9.9 PGP-2-3 2.0% .sub. 3.4 PGP-2-4 2.0% .sub.1 86 mPas PGP-2-5 2.0% V.sub.10 1.49 V PGUQU-3-F 8.0% LTS 1000 h

(4) TABLE-US-00011 CCGU-3-F 5.0% CCQU-2-F 7.0% CCQU-3-F 7.0% CCQU-5-F 6.0% CBC-33F 2.0% CPGU-3-OT 6.0% BCH-3F.F.F 5.0%

EXAMPLE 3

(5) TABLE-US-00012 CCH-23 17.0% cl.p. 74.5 C. CCH-34 6.5% n 0.0992 PCH-301 15.5% +7.1 CCH-301 8.5% .sub.|| 10.7 PGUQU-3-F 9.0% .sub. 3.6 CCGU-3-F 5.5% .sub.1 75 mPas CCQU-2-F 5.5% V.sub.10 1.43 V CCQU-3-F 4.0% LTS 1000 h CCQU-5-F 4.0% CBC-33F 2.0% CPGU-3-OT 3.5% CPU-3-OXF 19.0%

EXAMPLE 4

(6) TABLE-US-00013 CCH-23 17.5% cl.p. 74.5 C. CCH-34 11.5% n 0.1014 PCH-301 16.5% +6.2 CCH-301 9.5% .sub.|| 9.7 PGUQU-3-F 8.0% .sub. 3.5 CCGU-3-F 9.0% .sub.1 76 mPas CBC-33F 2.0% V.sub.10 1.55 V CPGU-3-OT 3.0% CPU-3-OXF 23.0%

COMPARATIVE EXAMPLE 2

(7) TABLE-US-00014 CC-3-V 52.0% cl.p. 75.5 C. APUQU-3-F 14.0% n 0.1187 BCH-32 7.0% +4.6 GGP-3-CL 2.0% .sub.|| 7.6 PGP-2-3 9.0% .sub. 3.0 PGP-2-4 10.0% .sub.1 54 mPas PGP-2-5 2.0% V.sub.10 1.96 V PUQU-3-F 4.0% LTS 20 C. 1000 h LTS 30 C. 168 h

EXAMPLE 5

(8) TABLE-US-00015 BCH-32 5.0% cl.p. 74.0 C. PUQU-3-F 6.5% n 0.1182 PGP-2-3 6.0% +4.1 PGP-2-4 6.0% .sub.|| 7.2 PGP-2-5 8.0% .sub. 3.2 CCQU-2-F 2.0% .sub.1 66 mPas CCQU-3-F 5.0% V.sub.10 1.92 V CCQU-5-F 2.5% LTS 20 C. 1000 h PCH-301 16.0% LTS 30 C. 1000 h CCH-301 5.0% CCH-23 15.5% CCH-34 11.0% CPGU-3-OT 4.5% CCGU-3-F 7.0%

EXAMPLE 6

(9) TABLE-US-00016 BCH-32 5.0% cl.p. 74.0 C. PUQU-3-F 5.0% n 0.1167 PGP-2-3 4.0% +4.3 PGP-2-4 3.5% .sub.|| 7.5 PGP-2-5 7.5% .sub. 3.2 PCH-301 16.0% .sub.1 67 mPas CCH-301 3.5% V.sub.10 1.91 V CCH-23 17.5% LTS 20 C. 1000 h CCH-34 11.5% LTS 30 C. 1000 h CCGU-3-F 9.0% CPU-3-OXF 17.5%

EXAMPLE 7

(10) TABLE-US-00017 PUQU-3-F 7.0% cl.p. 75.0 C. PGP-2-3 7.5% n 0.1170 PGP-2-4 7.0% +3.6 PGP-2-5 9.0% .sub.|| 6.8 CCQU-2-F 4.0% .sub. 3.2 CCQU-3-F 4.5% .sub.1 75 mPas CCQU-5-F 4.0% V.sub.10 1.97 V PCH-301 14.0% LTS 20 C. 1000 h CCH-301 8.0% LTS 30 C. 1000 h CCH-23 14.5% CCH-34 10.0% CCGU-3-F 6.5% CPGP-4-3 4.0%

EXAMPLE 8

(11) TABLE-US-00018 PGP-2-3 4.5% cl.p. 74.0 C. PGP-2-4 4.5% n 0.1173 PGP-2-5 7.5% +3.8 PCH-301 15.5% .sub.|| 7.1 CCH-301 9.0% .sub. 3.3 CCH-23 16.0% .sub.1 70 mPas CCH-34 9.0% V.sub.10 1.94 V CPGU-3-OT 3.5% LTS 20 C. 1000 h CPU-3-OXF 19.5% LTS 30 C. 1000 h CBC-33F 3.5% PGUQU-3-F 2.0% BCH-3F.F.F 5.5%

EXAMPLE 9

(12) TABLE-US-00019 PGP-2-3 5.0% cl.p. 75.0 C. PGP-2-4 4.5% n 0.1172 PGP-2-5 6.5% +3.7 PCH-301 16.0% .sub.|| 6.9 CCH-301 8.5% .sub. 3.3 CCH-23 17.0% .sub.1 68 mPas CCH-34 10.5% V.sub.10 1.99 V CCGU-3-F 5.5% LTS 20 C. 1000 h CPU-3-OXF 20.0% LTS 30 C. 1000 h CPGP-4-3 3.0% PGUQU-3-F 3.5%

EXAMPLE 10

(13) TABLE-US-00020 PGP-2-3 5.5% cl.p. 75.0 C. PGP-2-4 5.0% n 0.1167 PGP-2-5 8.0% +3.7 CCQU-2-F 4.5% .sub.|| 7.0 CCQU-3-F 4.5% .sub. 3.3 CCQU-5-F 4.0% .sub.1 70 mPas PCH-301 15.5% V.sub.10 1.95 V CCH-301 8.5% LTS 20 C. 1000 h CCH-23 15.5% LTS 30 C. 1000 h CCH-34 6.0% CPGU-3-OT 3.0% CPU-3-OXF 17.5% CPGP-4-3 2.5%

COMPARATIVE EXAMPLE 3

(14) TABLE-US-00021 CC-3-V 30.0% cl.p. 76.0 C. CCP-V-1 16.5% n 0.1321 GGP-3-CL 5.0% +6.0 BCH-3F.F.F 14.0% .sub.|| 9.3 PUQU-3-F 15.0% .sub. 3.3 PGP-2-3 5.5% .sub.1 69 mPas PGP-2-4 6.0% V.sub.10 1.68 V PGP-2-5 8.0%

EXAMPLE 11

(15) TABLE-US-00022 BCH-32 5.0% cl.p. 75.5 C. PUQU-3-F 7.5% n 0.1316 PGP-2-3 6.5% +6.2 PGP-2-4 6.5% .sub.|| 9.6 PGP-2-5 8.0% .sub. 3.4 CCQU-2-F 2.0% .sub.1 86 mPas CCQU-3-F 3.0% V.sub.10 1.66 V CCQU-5-F 2.5% PCH-301 17.5% PCH-3CL 4.5% CCH-23 13.5% CCH-34 7.0% CPGU-3-OT 5.5% CCGU-3-F 5.5% PGUQU-3-F 5.5%

EXAMPLE 12

(16) TABLE-US-00023 PGP-2-3 6.0% cl.p. 75.0 C. PGP-2-4 6.0% n 0.1317 PGP-2-5 8.5% +5.4 PCH-301 16.5% .sub.|| 8.8 CCH-301 7.5% .sub. 3.4 CCH-23 16.0% .sub.1 78 mPas CCH-34 6.5% V.sub.10 1.73 V CPGU-3-OT 3.5% CPU-3-OXF 18.0% CBC-33F 1.5% PGUQU-3-F 10.0%

EXAMPLE 13

(17) 0.04% of the following compound are added as stabiliser to the mixture from Example 1:

(18) ##STR00420##

EXAMPLE 14

(19) 0.05% of the following compound are added as stabiliser to the mixture from Example 5:

(20) ##STR00421##

EXAMPLE 15

(21) 0.03% of the following compound are added as stabiliser to the mixture from Example 11:

(22) ##STR00422##

EXAMPLE 16

(23) 0.04% of the following compound are added as stabiliser to the mixture from Example 2:

(24) ##STR00423##

EXAMPLE 17

(25) 0.03% of the following compound are added as stabiliser to the mixture from Example 7:

(26) ##STR00424##

(27) VHR Measurements

(28) In order to determine the voltage holding ratio (VHR) or its stability after BL stress (BL=backlight), the respective mixture is filled into a test cell having an orientation material for parallel alignment in the TN configuration and flat ITO electrodes. The VHR of the respective mixture is then measured (measuring instrument: Autronic VHRM 105, signal amplitude: 1 V, pulse width 60 s, measurement frequency 60 Hz, temperature 100 C.).

(29) The corresponding test cells are subsequently exposed to illumination with a cold-cathode (CCFL) LCD backlight for a duration of up to 1000 hours. The VHR is in each case measured as described above after certain time intervals.

(30) For each individual measurement, a measurement series of 4 test cells in each case is filled and investigated. The values indicated are the average of the individual values measured. The results are summarised in Table 1.

(31) TABLE-US-00024 TABLE 1 VHR values Mixture VHR (%) cf. Ex. 1 1 cf. Ex. 3 11 12 initial 98.8 98.8 98.3 97.1 96.9 BL 48 h 98.3 99.0 98.3 97.7 96.5 BL 96 h 97.6 98.9 96.6 97.3 96.0 BL 360 h 94.7 98.4 94.8 96.8 95.0 BL 550 h 93.4 98.3 93.8 .sup.1) 96.5 .sup.1) 94.1 .sup.1) BL 720 h 92.0 98.1 BL 1000 h 89.9 98.0 .sup.1) after 500 h

(32) It can be seen from Table 1 that the mixtures according to the invention have a significantly smaller reduction in the VHR after BL stress and consequently significantly higher VHR stability than the comparative mixtures.

(33) It can additionally be seen from the examples indicated above that the mixtures according to the invention have at least equally good or higher LTS values, in particular at low temperatures (30 C.), compared with the comparative mixtures.