Liquid crystal medium

1. A liquid-crystalline medium comprising a mixture of polar compounds having positive dielectric anisotropy, comprising at least one compound of the formula I in a total concentration of ≥40%,

from 6% to 13% of at least one compound of formula IV-8 or IV-11

and

at least one compound of formula IB

in which

R 1 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more H atoms in these radicals may be replaced by F and, in addition, one or more CH 2 groups may each be replaced, independently of one another, by

—C≡C—, —CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another,

on each occurrence, identically or differently, denote

L 11 and L 12 , independently of one another, denote H or F,

X 1 denotes F, Cl, CN, a halogenated alkyl radical, a halogenated alkenyl radical, a halogenated alkoxy radical or a halogenated alkenyloxy radical having up to 6 C atoms

R 41 and R 42 , independently of one another, denote n-alkyl having 1 to 7 C atoms,

wherein the clearing temperature of said liquid-crystalline medium is at least 120° C.

2. The liquid-crystalline medium according to claim 1 , comprising at least one compound of formulae I-1 to I-5,

in the parameters have the meanings indicated in claim 1 and L 13 and L 14 , independently of one another, denote H or F.

3. The liquid-crystalline medium according to claim 1 , additionally comprising at least one compound of the formula II

in which

R 2 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more H atoms in these radicals may be replaced by F and, in addition, one or more CH 2 groups may each be replaced, independently of one another, by

—C≡C—, —CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another,

on each occurrence, identically or differently, denote

L 21 and L 22 , independently of one another, denote H or F,

X 2 denotes F, Cl, CN, a halogenated alkyl radical, a halogenated alkenyl radical, a halogenated alkoxy radical or a halogenated alkenyloxy radical having up to 6 C atoms,

Z 2 denotes —CH 2 CH 2 —, —CF 2 CF 2 —, —COO—, trans —CH═CH—, trans —CF═CF—, —CH 2 O— or a single bond.

4. The liquid-crystalline medium according to claim 3 , wherein the at least one compound of the formula II are of the formulae II-1 to II-14,

in which

R 2 denotes n-alkyl having up to 7 C atoms,

L 21 and L 22 , independently of one another, denote H or F and

X 2 denotes F, Cl, halogenated alkyl or halogenated alkoxy having up to 6 C atoms.

5. The liquid-crystalline medium according to claim 3 , wherein the total concentration of the compounds of the formula II is 18% to 50%.

6. The liquid-crystalline medium according to claim 1 , wherein said liquid-crystalline medium additionally comprises at least one compound of the formulae IA or IB-1,

wherein in formula IA

R 1 , A 11 , A 12 , L 11 , L 12 and X 1 have the meanings indicated in claim 1 and L 13 and L 14 have the meaning indicated for L 11 and

in formula IB-1 at least one of L 11 and L 12 denotes F and one of L 11 and L 12 has the meaning indicated in claim 1 and X 1 denotes F, Cl, CF 3 or OCF 3 and R 1 has the meanings indicated in claim 1 .

7. The liquid-crystalline medium according to claim 1 , wherein said liquid-crystalline medium additionally comprises at least one compound of the formula III,

in which

R 3 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more H atoms in these radicals may be replaced by F and, in addition, one or more CH 2 groups may each be replaced, independently of one another, by

—CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another,

on each occurrence, independently of one another, denote

and

Z 3 on each occurrence, independently of one another, denotes —CH 2 CH 2 —, —COO—, trans —CH═CH—, trans —CF═CF—, —CH 2 O—, —C≡C—or a single bond,

L 31 , L 32 denote H or F,

X 3 denotes F, Cl, CN, 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 7 , wherein the at least one compound of the formula III is of the formulae III-1 to III-9,

in which

R 3 , L 31 and L 32 have the meanings indicated in claim 7 and

X 3 denotes F, Cl, halogenated alkyl or halogenated alkoxy having to 6 C atoms.

9. A method which comprises including a liquid-crystalline medium according to claim 1 in an electro-optical component.

10. A method according to claim 9 wherein the electro-optical component is a liquid-crystal light valve for lighting devices for motor vehicles or a liquid-crystal display.

11. An electro-optical component comprising a liquid-crystalline medium according to claim 1 .

12. The electro-optical component according to claim 11 , where the component is a liquid-crystal light valve.

13. A lighting device for motor vehicles containing a liquid-crystal light valve according to claim 12 .

14. A liquid-crystal display containing a liquid-crystal light valve according to claim 12 .

15. The liquid crystalline medium of claim 1 , wherein the clearing temperature of said liquid-crystalline medium is at least 130° C.

16. The liquid crystalline medium of claim 1 , wherein the clearing temperature of said liquid-crystalline medium is at least 140° C.

17. The liquid crystalline medium of claim 1 , wherein the medium retain the nematic phase down to −30° C. and the nematic phase range is at least 140 K.

18. The liquid crystalline medium of claim 1 , wherein the medium retain an optical anisotropy (Δn) from 0.060 to 0.100, have a clearing point of at least 130° C. and the nematic phase range is at least 180 K.

19. The liquid crystalline medium of claim 1 , wherein the medium has a TN threshold below 2.0 V.

20. The liquid crystalline medium of claim 3 , wherein the tota concentration of compounds of the formula II in the medium is from 23% to 45%.