LIQUID CRYSTALLINE MEDIUM

Abstract

The present invention relates to liquid-crystalline media (LC media), characterised in that they comprise one or more compounds of the formula I,

##STR00001## and one or more compounds of the formula II,

##STR00002## where the parameters have the meaning indicated in claim 1, to the use thereof in electro-optical displays, and to LC displays which contain these LC media.

Claims

1. LC medium, characterised in that it comprises one or more compounds of the formula I, ##STR00200## in which the individual radicals have the following meanings: R.sup.1 and R.sup.2 denote H, F, Cl, Br, CN, SCN, NCS, SF.sub.5 or straight-chain or branched alkyl having 1 to 12 C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced, independently of one another, byCH?CH, C?C, O, CO, COO, OCO, OCOO 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 F, Cl or Br, A.sup.0, A.sup.1 and A.sup.2 each, independently of one another, denote phenylene-1,4-diyl, in which, in addition, one or two CH groups may be replaced by N and one or more H atoms may be replaced by halogen, CN, CH.sub.3, CHF.sub.2, CH.sub.2F, CF.sub.3, OCH.sub.3, OCHF.sub.2 or OCF.sub.3, cyclohexane-1,4-diyl, in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced, independently of one another, by O and/or S and one or more H atoms may be replaced by F, cyclohexene-1,4-diyl, bicyclo-[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]-heptane-2,6-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl, Z.sup.1 and Z.sup.2 each, independently of one another, denote CF.sub.2O, OCF.sub.2, CH.sub.2O, OCH.sub.2, COO, OCO, C.sub.2H.sub.4, C.sub.2F.sub.4, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, CFHCFH, CFHCH.sub.2, CH.sub.2CFH, CF.sub.2CFH, CFHCF.sub.2, CH?CH, CF?CH, CH?CF, CF?CF, C?C or a single bond, m and n each, independently of one another, denote 0, 1, 2 or 3, and one or more compounds selected from the group of the compounds of the formula II, ##STR00201## in which q denotes 1 or 2, p denotes (2-q), Z.sup.11 and Z.sup.12, independently of one another, denote O, (C?O) or a single bond, but do not both simultaneously denote O, r and s, independently of one another, denote 0 or 1, Y.sup.11 to Y.sup.14 each, independently of one another, denote alkyl having 1 to 4 C atoms and alternatively also, independently of one another, one or both of the pairs (Y.sup.11 and Y.sup.12) and (Y.sup.13 and Y.sup.14) together denote a divalent group having 3 to 6 C atoms, R.sup.11 on each occurrence, independently of one another, denotes H, alkyl, O-alkyl, O-cycloalkyl, O.sup.? or OH, Sp.sup.11 denotes a straight-chain or branched alkyl chain having 2-20 C atoms, in which one or more CH.sub.2 groups may be replaced by O, but two adjacent CH.sub.2 groups cannot be replaced by O, or denotes a hydrocarbon radical which contains a cycloalkyl or alkylcycloalkyl unit and in which one or more CH.sub.2 groups may be replaced by O, but two adjacent CH.sub.2 groups cannot be replaced by O.

2. LC medium according to claim 1, characterised in that it comprises one or more compounds of the formula I selected from the group of the compounds I1 to I16, ##STR00202## ##STR00203## ##STR00204## in which R.sup.1, R.sup.2 and L.sup.1 to L.sup.6 have the meanings indicated in claim 1.

3. LC medium according to claim 1, characterised in that, in formula I, m denotes 1, n denotes 0 and A.sup.0 denotes ##STR00205##

4. LC medium according to claim 1, characterised in that it additionally comprises one or more compounds of the formula III and/or IV: ##STR00206## in which A denotes 1,4-phenylene or trans-1,4-cyclohexylene, a is 0 or 1, R.sup.3 denotes alkyl or alkenyl having up to 9 C atoms, and R.sup.4 denotes alkyl having 1 to 12 C atoms, where, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by O, CH?CH, CO, OCO or COO in such a way that O atoms are not linked directly to one another.

5. LC medium according to claim 1, characterised in that it additionally comprises one or more compounds selected from the group consisting of the following formulae: ##STR00207## in which 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 C?C, CF.sub.2O, CH?CH, ##STR00208## 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, CN, SF.sub.5, SCN, NCS, a halogenated alkyl radical, halogenated alkenyl radical, halogenated alkoxy radical or halogenated alkenyloxy radical, each having up 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, 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, CF.sub.2O or OCF.sub.2, in the formulae V and VI also a single bond, and b and c each, independently of one another, denote 0 or 1.

6. LC medium according to claim 1, characterised in that it additionally comprises one or more compounds selected from the group consisting of the following formulae: ##STR00209## in which R.sup.0 , X.sup.0 and Y.sup.1-4 have the meanings indicated above, and ##STR00210## each, independently of one another, denote ##STR00211##

7. LC medium according to claim 1, characterised in that the total concentration of the compounds of the formula II in the LC medium is in the range from 10 ppm to 10,000 ppm.

8. LC medium according to claim 1, characterised in that the compounds of the formula II are selected from the group of the compounds of the formulae I11 to I15, ##STR00212##

9. LC medium according to claim 1, characterised in that the total concentration of the compounds of the formula I in the medium as a whole is 1% to 25%.

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

11. LC display containing an LC medium according to claim 1.

12. Display according to claim 11, characterised in that it is based on the IPS or FFS effect.

13. Display according to claim 11, characterised in that it has an active-matrix addressing device.

14. Process for the preparation of an LC medium according to claim 1, characterised in that one or more compounds of the formula I are mixed with one or more compounds of the formula II and with one or more further mesogenic compounds.

Description

EXAMPLES

Thiophene-Containing Base Mixture M1

[0238] A nematic LC mixture is formulated as follows:

TABLE-US-00007 APUQU-2-F 12.0% Cl.p. +80? C. APUQU-3-F 12.0% ?.sub.1 71 mPa s CC-3-V 36.0% ?n 0.111 CC-3-V1 4.0% ?? +10.6 CCP-V-1 12.0% HR.sub.100 (1 h UV) 44% CCQU-3-F 6.0% PUQU-3-F 9.0% PUS-3-2 9.0%

Mixture Example 1 (Mixture M1 Stabilised with Tinuvin? 770)

[0239] A nematic LC mixture according to the invention is formulated as follows:

TABLE-US-00008 Mixture M1 99.999% HR.sub.100 (1 h UV) 64% Tinuvin? 770 100 ppm

[0240] Addition of 100 ppm of Tinuvin? 770 significantly improves the HR.sub.100 after UV exposure compared with the unstabilised mixture Ml.

Mixture Example 2 (Mixture M1 Stabilised with Tinuvin? 770)

[0241] A nematic LC mixture according to the invention is formulated as follows:

TABLE-US-00009 Mixture M1 99.99% HR.sub.100 (1 h UV) 83% Tinuvin? 770 1000 ppm

[0242] Addition of 1000 ppm of Tinuvin? 770 significantly improves the HR.sub.100 after UV exposure compared with Mixture Example 1 comprising 100 ppm of stabiliser and very considerably compared with the unstabilised mixture M1.

Mixture Example 3 (Mixture M1 Stabilised with Tinuvin? 770 and Tinuvin? P)

[0243] A nematic LC mixture according to the invention is formulated as follows:

TABLE-US-00010 Mixture M1 99.699% HR.sub.100 (1 h UV) 74% Tinuvin? P 0.30% Tinuvin? 770 100 ppm

[0244] The HR.sub.100 can be improved further compared with Mixture Example 1 by additional use of Tinuvin? P, but this combination is, in spite of the significantly higher concentration of stabiliser overall, less effective than on use of 1000 ppm of Tinuvin? 770 alone (Mixture Example 2).

Thiophene-Containing Base Mixture M2

[0245] A nematic LC mixture is formulated as follows:

TABLE-US-00011 PUQU-3-F 5.0% Cl.p. +74.5? C. PGUQU-3-F 7.0% ?.sub.1 55 mPa .Math. s APUQU-2-F 8.0% ?n 0.1026 APUQU-3-F 8.0% ?? +7.6 CC-3-V 47.0% HR.sub.100 (1 h UV) 51% CC-3-V1 7.0% CCP-V-1 11.0% PUS-2-2 7.0%

Mixture Example 4 (Mixture M2 Stabilised with Tinuvin? 770)

[0246] A nematic LC mixture according to the invention is formulated as follows:

TABLE-US-00012 Mixture M2 99.99% HR.sub.100 (1 h UV) 79% Tinuvin? 770 1000 ppm

Thiophene-Containing Base Mixture M3

[0247] A nematic LC mixture is formulated as follows:

TABLE-US-00013 PUQU-3-F 9.0% Cl.p. +74.0? C. CPGU-3-OT 9.0% ?.sub.1 61 mPa s PUQU-2-F 14.0% ?n 0.132 CC-3-V 43.5% ?? +7.9 CCP-V-1 4.5% HR.sub.100 (1 h UV) 48% PP-1-2V1 3.0% PGP-2-2V 11.0% PUS-3-2 6.0%

Mixture Example 5 (Mixture M3 Stabilised with Tinuvin? 770) A nematic LC mixture according to the invention is formulated as follows:

[0248]

TABLE-US-00014 Mixture M3 99.99% HR.sub.100 (1 h UV) 81% Tinuvin? 770 1000 ppm

Thiophene-Containing Base Mixture M4

[0249] A nematic LC mixture is formulated as follows:

TABLE-US-00015 PUQU-3-F 8.0% Cl.p. +74.0? C. CPGU-3-OT 5.5% ?.sub.1 58 mPa .Math. s PUQU-2-F 15.0% ?n 0.132 CC-3-V 44.0% ?? +7.2 CCP-V-1 7.0% HR.sub.100 (1 h UV) 55% PGP-2-2V 3.0% CPGP-4-3 1.5% PUS-3-2 16.0%

Mixture Example 6 (Mixture M4 Stabilised with Tinuvin? 770)

[0250] A nematic LC mixture according to the invention is formulated as follows:

TABLE-US-00016 Mixture M4 99.99% HR.sub.100 (1 h UV) 79% Tinuvin? 770 1000 ppm

[0251] Mixture Examples 4 to 6 show a significant Improvement in the HR.sub.100 compared with the unstabilised base mixtures.