Liquid-crystal medium

1 . A liquid-crystal medium having a positive dielectric anisotropy and comprising at least two or more compounds of formula I-2-a

in which

R 11 and R 12 identically or differently, denote an alkyl radical having 1 to 12 C atoms,

at least two stabilizers selected from the group consisting of compounds of the formulae ST-a to ST-r

in which

R ST denotes H, an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH 2 groups in these radicals may each be replaced, independently of one another, by —C≡C—, —CF 2 O—, —OCF 2 —, —CH═CH—, -⋄-, -⋄⋄-, —O—, —CO—O— or —O—CO— 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 each be replaced by halogen,

Z ST denotes —CO—O—, —O—CO—, —CF 2 O—, —OCF 2 —, —CH 2 O—, —OCH 2 —, —CH 2 —, —CH 2 CH 2 —, —(CH 2 ) 4 —, —CH═CH—CH 2 —, —C 2 F 4 —, —CH 2 CF 2 —, —CF 2 CH 2 —, —CF═CF—, —CH═CF—, —CF═CH—, —CH═CH—, —C═C— or a single bond,

L 1 and L 2 each, independently of one another, denote F, Cl, CF 3 or CHF 2 ,

p denotes 1 or 2, and

q denotes 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; and

wherein the medium comprises at least one compound of formula II-B, at least one compound of formula II-C, and at least one compound of formula II-D, the at least one compound of formula II-B, at least one compound of formula II-C, and at least one compound of formula II-D being collectively present in a total amount of at least 15% by weight; and

in which R 2 denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy with 1 to 7 C atoms, or alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl with 2 to 7 C atoms, in which optionally one or more CH 2 groups, independently of one another, may be replaced by

one or more compounds of formula VI-1 in a total amount of at least 10% by weight:

in which

R 61 and R 62 independently of each other, denote alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy with 1 to 7 C atoms, or alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl with 2 to 7 C atoms; and

wherein the medium comprises one or more compounds of formula III-1:

in which R 3 denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy with 1 to 7 C atoms, or alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl with 2 to 7 C atoms, in which optionally one or more CH 2 groups, independently of one another, may be replaced by

one or more compounds of Formula Y2-10 in a total amount of at least 1% by weight to 15% by weight:

in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms.

2 . The liquid-crystal medium according to claim 1 , further comprising one or more compounds selected from the group of compounds of formulae I-1 and I-3

in which

R 11 and R 12 identically or differently, denote H, an alkyl or alkoxy radical having 1 to 15 C atoms, in which one or more CH 2 groups in these radicals are optionally replaced, independently of one another, by —C≡C—, —CF 2 O—, —OCF 2 —, —CH═CH—,

 —O—, —CO—O— or —O—CO— 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.

3 . The liquid-crystal medium according to claim 1 , wherein R 11 and R 12 denote, identically or differently, a straight-chain alkoxy radical having 1 to 7 C atoms.

4 . The liquid-crystal medium according to claim 1 , wherein the medium comprises one or more compounds of formula IV

in which

R 41 and R 42 independently of each other, denote alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy with 1 to 7 C atoms, or alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl with 2 to 7 C atoms,

 on each occurrence, identically or differently, denote

Z 41 , Z 42 on each occurrence, identically or differently, denote —CH 2 CH 2 —, —COO—, trans-CH═CH—, trans-CF═CF—, —CH 2 O—, —CF 2 O—, —C≡C— or a single bond, preferably a single bond, and

p is 0, 1 or 2, preferably is 0.

5 . The liquid-crystal medium according to claim 1 , wherein the medium comprises one or more compounds of formula IV-1

in which

R 41 and R 42 independently of each other, denote alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy with 1 to 7 C atoms, or alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl with 2 to 7 C atoms.

6 . The liquid-crystal medium according to claim 1 , wherein the medium comprises one or more compounds selected from the group of compounds of formulae Y1 and LY

in which

R 1 , R 2 independently of each other, denote a straight-chain, branched or cyclic alkyl or alkoxy radical that is unsubstituted or halogenated and has 1 to 15 C atoms, where, in addition, one or more CH 2 groups in these radicals may each be replaced, independently of one another, by —C≡C—, —CFO—, —CH═CH—,

a and x identically or differently, are 1 or 2.

7 . The liquid-crystal medium according to claim 1 , wherein the medium comprises one or more compounds selected from the compounds ST-1, ST-2 and ST-3

8 . The liquid-crystal medium according to claim 1 ,

wherein the medium has a dielectric anisotropy in the range of from +5.0 to +8.0.

9 . TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, PS-HB-FFS, SA-HB-FFS, polymer stabilised SA-HB-FFS, positive VA and positive PS-VA displays, light shutters, switchable windows, or 3D applications comprising the liquid crystal medium of claim 1 .

10 . A liquid-crystal display comprising a liquid-crystal medium according to claim 1 .

11 . The liquid-crystal display according to claim 10 , wherein the display is a TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, PS-HB-FFS, SA-HB-FFS, polymer stabilised SA-HB-FFS, positive VA or positive PS-VA display.

12 . The liquid-crystal medium according to claim 7 , wherein the medium comprises at least two or more stabilizers selected from the compounds of formulae ST-1 and ST-3

13 . The liquid-crystal medium according to claim 12 , wherein the at least two or more stabilizers selected from the compounds of formulae ST-1 and ST-3 are present in the medium at 0.1% by weight to 0.2% by weight.

14 . The liquid-crystal medium according to claim 1 , wherein the at least two or more stabilizers are selected from the compounds of formulae: ST-h, ST-l and ST-r.