LIQUID CRYSTAL MIXTURE AND LIQUID CRYSTAL DISPLAY

Abstract

Liquid crystal mixtures containing a photoalignment component A) containing a photoreactive mesogen of formula I,

##STR00001## a liquid-crystalline component B) containing one or more nematogenic compounds, and a polymerizable component C) containing one or more polymerizable compounds of formula P,

P.sup.a-Sp.sup.a-(A.sup.p).sub.n2-Sp.sup.b-P.sup.b P and a method of producing such LC media, the use of such media in LC devices, and LC devices containing such a LC medium, and further a process for the fabrication of such liquid crystal displays and the use of the liquid crystal mixtures for the fabrication of such liquid crystal display.

Claims

1. Liquid crystal mixture, comprising a photoalignment component A) comprising one or more photoreactive mesogens of formula I, ##STR00437## wherein A.sup.11 denotes a radical selected from the following groups: a) a group consisting of 1,4-phenylene and 1,3-phenylene, wherein, in addition, one or two CH groups may be replaced by N and wherein, in addition, one or more H atoms may be replaced by L, b) a group selected from the group consisting of ##STR00438## where, in addition, one or more H atoms in these radicals may be replaced by L, and/or one or more double bonds may be replaced by single bonds, and/or one or more CH groups may be replaced by N, A have each, independently of one another, in each occurrence one of the meanings for A.sup.11 or a) group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, wherein, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by —O— and/or —S— and wherein, in addition, one or more H atoms may be replaced by F, or b) a group consisting of tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, L on each occurrence, identically or differently, denotes —OH, —F, —Cl, —Br, —I, —CN, —NO.sub.2, SF.sub.5, —NCO, —NCS, —OCN, —SCN, —C(═O)N(R.sup.z).sub.2, —C(═O)R.sup.z, —N(R.sup.z).sub.2, optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or straight-chain or branched or cyclic alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, or X.sup.21—Sp.sup.21-R.sup.21, M denotes —O—, —S—, —CH.sub.2—, —CHR.sup.z— or —CR.sup.yR.sup.z—, R.sup.y and R.sup.z each, independently of one another, denote H, CN, F or alkyl having 1-12 C atoms, wherein one or more H atoms may be replaced by F, Y.sup.11 and Y.sup.12 each, independently of one another, denote H, F, phenyl or optionally fluorinated alkyl having 1-12 C atoms, Z denotes, independently of each other, in each occurrence, a single bond, —COO—, —OCO—, —O—CO—O—, —OCH.sub.2—, —CH.sub.2O—, —OCF.sub.2—, —CF.sub.2O—, —(CH.sub.2).sub.n—, —CF.sub.2CF.sub.2—, —CH═CH—, —CF═CF—, —CH═CH—COO—, —OCO—CH═CH—, —CO—S—, —S—CO—, —CS—S—, —S—CS—, —S—CSS— or —C≡C—, n denotes an integer between 2 and 8, and p denote each and independently 0, 1 or 2, X.sup.11 and X.sup.21 denote independently from one another, in each occurrence a single bond, —CO—O—, —O—CO—, —O—COO—, —O—, —CH═CH—, —C≡C—, —CF.sub.2—O—, —CF.sub.2—, —CF.sub.2—CF.sub.2—, —CH.sub.2—O—, —O—CH.sub.2—, —CO—S—, —S—CO—, —CS—S—, —S—CS—, —S—CSS— or —S—, Sp.sup.11 and Sp.sup.21 denote each and independently, in each occurrence a single bond or a spacer group comprising 1 to 20 C atoms, wherein one or more non-adjacent and non-terminal CH.sub.2 groups may also be replaced by —O—, —S—, —NH—, —N(CH.sub.3)—, —CO—, —O—CO—, —S—CO—, —O—COO—, —CO—S—, —CO—O—, —CF.sub.2—, —CF.sub.2O—, —OCF.sub.2— —C(OH)—, —CH(alkyl)-, —CH(alkenyl)-, —CH(alkoxyl)-, —CH(oxaalkyl)-, —CH═CH— or —C≡C—, however in such a way that no two O-atoms are adjacent to one another and no two groups selected from —O—CO—, —S—CO—, —O—COO—, —CO—S—, —CO—O— and —CH═CH— are adjacent to each other, R.sup.11 denotes P, R.sup.21 denotes P, halogen, CN, optionally fluorinated alkyl or alkenyl with up to 15 C atoms in which one or more non-adjacent CH.sub.2-groups may be replaced by —O—, —S—, —CO—, —C(O)O—, —O—C(O)—, O—C(O)—O—, P each and independently from another in each occurrence a polymerizable group, a liquid-crystalline component B), comprising one or more nematogenic compounds, and a polymerizable component C) comprising one or more polymerizable compounds of formula P,
P.sup.a—Sp.sup.a-(A.sup.p).sub.n2-Sp.sup.b-P.sup.b P wherein the individual radicals have the following meanings: P.sup.a P.sup.b each, independently of one another, denote a polymerizable group, preferably each and independently selected from the group consisting of acrylate, methacrylate, ethacrylate, fluoroacrylate, vinyl¬oxy, chloro¬acry-late, oxetane, or epoxide groups Sp.sup.a, Sp.sup.b on each occurrence, identically or differently, denote a spacer group or a single bond, A.sup.p each and independently from another, in each occurrence, a group selected from 5, 6 or 7-membered alicyclic groups wherein, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by —NH—, —O— and/or —S—, wherein one or more non-adjacent —CH.sub.2—CH.sub.2— groups may be replaced by —CH═CH—, and wherein one or more H atoms may be replaced by F, n2 denotes 0, 1, 2 or 3.

2. Liquid crystal mixture according to claim 1 characterised in that the total concentration of compounds of formula I in the mixture is in the range of from 0.01 to 10% by weight.

3. Liquid crystal mixture according to claim 1, characterised in that the concentration of the polymerizable component C) is in the range of from 0.1 to 5% by weight.

4. Liquid crystal mixture according to claim 1, characterised in that it comprises one or more compounds of formulae P-1 to P-4 ##STR00439##

5. Liquid crystal mixture according to claim 1, characterized in that the LC host mixture has negative dielectric anisotropy.

6. Liquid crystal mixture according to claim 5, characterised in that the LC host mixture comprises one or more compounds selected from the following formulae: ##STR00440## wherein a is 1 or 2, b is 0 or 1, ##STR00441## denotes ##STR00442## R.sup.1 and R.sup.2 each, independently of one another, denote 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—, —O—CO— or —CO—O— in such a way that O atoms are not linked directly to one another, Z.sup.x denotes —CH═CH—, —CH.sub.2O—, —OCH.sub.2—, —CF.sub.2O—, —OCF.sub.2—, —O—, —CH.sub.2—, —CH.sub.2CH.sub.2— or a single bond, L.sup.1-4 each, independently of one another, denote F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F, CHF.sub.2.

7. Liquid crystal mixture according to claim 1, characterised in that the LC host mixture has positive dielectric anisotropy.

8. Liquid crystal mixture according to claim 7, characterised in that the LC host mixture comprises one or more compounds selected from the group consisting of the compounds of the formulae II and III, ##STR00443## wherein R.sup.20 each, identically or differently, denote a halogenated or unsubstituted 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—, ##STR00444## —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, X.sup.20 each, identically or differently, denote F, Cl, CN, SF.sub.5, SCN, NCS, a halogenated alkyl radical, a halogenated alkenyl radical, a halogenated alkoxy radical or a halogenated alkenyloxy radical, each having up to 6 C atoms, and Y.sup.20-24 each, identically or differently, denote H or F, W denotes H or methyl, ##STR00445## each, identically or differently, denote ##STR00446##

9. Liquid crystal mixture according to claim 8, characterised in that it comprises one or more compounds selected from the group consisting of compounds of formulae XI and XII ##STR00447## wherein R.sup.20, X.sup.20, W and Y.sup.20-23 have the meanings indicated in formula III in claim 8, and ##STR00448## each, independently of one another, denote ##STR00449## and ##STR00450## denotes ##STR00451##

10. Liquid crystal mixture according to claim 1, characterised in that the LC host mixture comprises one or more compounds of the following formula: ##STR00452## in which the individual radicals have the following meanings: ##STR00453## denotes ##STR00454## denotes ##STR00455## R.sup.3 and R.sup.4 each, independently of one another, denote alkyl having 1 to 12 C atoms, in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in such a way that O atoms are not linked directly to one another, Z.sup.y denotes —CH.sub.2CH.sub.2—, —CH═CH—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —CO—O—, —O—CO—, —C.sub.2F.sub.4—, —CF═CF—, —CH═CH—CH.sub.2O— or a single bond.

11. Liquid crystal mixture according to claim 1, characterised in that the LC host mixture comprises one or more compounds of the following formula ##STR00456## wherein the propyl, butyl and pentyl groups are straight-chain groups.

12. Liquid crystal mixture according to claim 1, characterised in that the LC host mixture comprises one or more compounds selected from the following formulae: ##STR00457## in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms.

13. Liquid crystal mixture according to claim 1, characterised in that the LC host mixture comprises one or more compounds selected from the following formulae: ##STR00458## in which alkyl* denotes an alkyl radical having 1-6 C atoms.

14. A liquid crystal display containing the liquid crystal mixture according to claim 1.

15. Process for the fabrication of a liquid crystal display, comprising at least the steps of: providing a first substrate which includes a pixel electrode and a common electrode for generating an electric field substantially parallel to a surface of the first substrate in the pixel region; providing a second substrate, the second substrate being disposed opposite to the first substrate; interposing a liquid crystal mixture according to claim 1; irradiating the liquid crystal mixture with linearly polarised light causing photoalignment of the liquid crystal; curing the polymerizable compounds of the liquid crystal mixture by irradiation with ultraviolet light or visible light having a wavelength of 450 nm or below.

16. Process according to claim 15, characterised in that the linearly polarised light is ultraviolet light or visible light having a wavelength of 450 nm or below.

17. Display, obtainable by a process according to claim 15.

18. Display according to claim 17, wherein the LC host mixture is homogeneously aligned without the application of an electric field.

19. Display according to claim 17, wherein the display is an IPS or FFS display.

Description

DETAILED DESCRIPTION

[0076] In detail, the present invention relates to compounds or photoreactive mesogens of formula I,

##STR00015##

wherein [0077] A.sup.11 denotes a radical selected from the following groups: [0078] a) a group consisting of 1,4-phenylene and 1,3-phenylene, wherein, in addition, one or two CH groups may be replaced by N and wherein, in addition, one or more H atoms may be replaced by L, [0079] b) a group selected from the group consisting of

##STR00016## ##STR00017## where, in addition, one or more H atoms in these radicals may be replaced by L, and/or one or more double bonds may be replaced by single bonds, and/or one or more CH groups may be replaced by N, [0080] A have each, independently of one another, in each occurrence one of the meanings for A.sup.11 or [0081] a) group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, wherein, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by —O— and/or —S— and wherein, in addition, one or more H atoms may be replaced by F, or [0082] b) a group consisting of tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, [0083] each of which may also be mono- or polysubstituted by L, [0084] L on each occurrence, identically or differently, denotes —OH, —F, —Cl, —Br, —I, —CN, —NO.sub.2, SF.sub.5, —NCO, —NCS, —OCN, [0085] —SCN, —C(═O)N(R.sup.z).sub.2, —C(═O)R.sup.z, —N(R.sup.z).sub.2, optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or straight-chain or branched or cyclic alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, preferably 1 to 12 C atoms, more preferably 1 to 6 C atoms, in which, in addition, one or more H atoms may be replaced by F or C, or X.sup.21-Sp.sup.21-R.sup.21, [0086] M denotes —O—, —S—, —CH.sub.2—, —CHR.sup.z— or —CR.sup.yR.sup.z—, and [0087] R.sup.y and R.sup.z each, independently of one another, denote H, CN, F or alkyl having 1-12 C atoms, wherein one or more H atoms may be replaced by F, [0088] preferably H, methyl, ethyl, propyl, butyl, [0089] more preferably H or methyl, [0090] in particular H, [0091] Y.sup.11 and Y.sup.12 each, independently of one another, denote H, F, phenyl or optionally fluorinated alkyl having 1-12 C atoms, preferably H, methyl, ethyl, propyl, butyl, more preferably H or methyl, [0092] in particular H, [0093] Z denotes, independently of each other, in each occurrence, a single bond, —COO—, —OCO—, —O—CO—O—, —OCH.sub.2—, —CH.sub.2O—, —OCF.sub.2—, —CF.sub.2O—, —(CH.sub.2).sub.n—, —CF.sub.2CF.sub.2—, —CH═CH—, —CF═CF—, —CH═CH—COO—, —OCOCH═CH—, —CO—S—, —S—CO—, —CS—S—, —S—CS—, —S—CSS— or —C≡C—, [0094] preferably a single bond, —COO—, —OCO—, —OCF.sub.2—, —CF.sub.2O—, or —(CH.sub.2).sub.n—, [0095] more preferably a single bond, —COO—, or —OCO—, [0096] n denotes an integer between 2 and 8, preferably 2, [0097] and p denote each and independently 0, 1 or 2, preferably 1, [0098] X.sup.11 and X.sup.21 denote independently from one another, in each occurrence a single bond, —CO—O—, —O—CO—, —O—COO—, —O—, —CH═CH—, —C≡C—, —CF.sub.2—O—, —O—CF.sub.2—, —CF.sub.2—CF.sub.2—, —CH.sub.2—O—, —O—CH.sub.2—, —CO—S—, —S—CO—, —CS—S—, —S—CS—, —S—CSS— or —S—, [0099] preferably, a single bond —CO—O—, —O—CO—, —O—COO—, or —O—, [0100] more preferably a single bond or —O—, [0101] Sp.sup.11 and Sp.sup.21 denote each and independently, in each occurrence a single bond or a spacer group comprising 1 to 20 C atoms, wherein one or more non-adjacent and non-terminal CH.sub.2 groups may also be replaced by —O—, —S—, —NH—, —N(CH.sub.3)—, —CO—, —O—CO—, —S—CO—, —O—COO—, —CO—S—, —CO—O—, —CF.sub.2—, —CF.sub.2O—, —OCF.sub.2— —C(OH)—, —CH(alkyl)-, —CH(alkenyl)-, —CH(alkoxyl)-, —CH(oxaalkyl)-, —CH═CH— or —C≡C—, however in such a way that no two O-atoms are adjacent to one another and no two groups selected from —O—CO—, —S—CO—, —O—COO—, —CO—S—, —CO—O— and —CH═CH— are adjacent to each other, [0102] preferably alkylene having 1 to 20, preferably 1 to 12, C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, [0103] more preferably straight-chain ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, [0104] R.sup.11 denotes P, [0105] R.sup.21 denotes P, halogen, CN, optionally fluorinated alkyl or alkenyl with up to 15 C atoms in which one or more non-adjacent CH.sub.2-groups may be replaced by —O—, —S—, —CO—, —C(O)O—, —O—C(O)—, O—C(O)—O—, preferably P, [0106] P each and independently from another in each occurrence a polymerizable group, [0107] q and r denotes each and independently an integer from 0 to 8, preferably q+r≥1 and ≤16, more preferably q and r each and independently denotes an integer from 1 to 8.

[0108] In the instant application, polymerizable groups (P) are groups that are suitable for a polymerisation reaction, such as, for example, free-radical or ionic chain polymerisation, polyaddition or polycondensation, or for a polymer-analogous reaction, for example addition or condensation onto a main polymer chain. Particular preference is given to groups for chain polymerisation, in particular those containing a C═C double bond or —C≡C— triple bond, and groups which are suitable for polymerisation with ring opening, such as, for example, oxetane or epoxide groups.

[0109] Preferred groups P are selected from the group consisting of CH.sub.2═CW.sup.1—CO—O—, CH.sub.2═CW.sup.1—CO—,

##STR00018##

CH.sub.2═CW.sup.2—(O).sub.k3—, CW.sup.1═CH—CO—(O).sub.k3—, CW.sup.1═CH—CO—NH—, CH.sub.2═CW.sup.1—CO—NH—, CH.sub.3—CH═CH—O—, (CH.sub.2═CH).sub.2CH—OCO—, (CH.sub.2═CH—CH.sub.2).sub.2CH—OCO—, (CH.sub.2═CH).sub.2CH—O—, (CH.sub.2═CH—CH.sub.2).sub.2N—, (CH.sub.2═CH—CH.sub.2).sub.2N—CO—, HO—CW.sup.2W.sup.3—, HS—CW.sup.2W.sup.3—, HW.sup.2N—, HO—CW.sup.2W.sup.3—NH—, CH.sub.2═CW.sup.1—CO—NH—, CH.sub.2═CH—(COO).sub.k1-Phe-(O).sub.k2—, CH.sub.2═CH—(CO).sub.k1-Phe-(O).sub.k2—, Phe-CH═CH—, HOOC—, OCN— and W.sup.4W.sup.5W.sup.6Si—, wherein W.sup.1 denotes H, F, Cl, CN, CF.sub.3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH.sub.3, W.sup.2 and W.sup.3 each, independently of one another, denote H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W.sup.4, W.sup.5 and W.sup.6 each, independently of one another, denote Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W.sup.7 and W.sup.8 each, independently of one another, denote H, Cl or alkyl having 1 to 5 C atoms, Phe denotes 1,4-phenylene, which is optionally substituted by one or more radicals L as defined above, k.sub.1, k.sub.2 and k.sub.3 each, independently of one another, denote 0 or 1, k.sub.3 preferably denotes 1, and k.sub.4 denotes an integer from 1 to 10.

[0110] Further preferred, P denotes a group

##STR00019## [0111] preferably a group

##STR00020## [0112] Y denotes H, F, phenyl or optionally fluorinated alkyl having 1-12 C atoms, preferably H, methyl, ethyl, propyl, butyl, [0113] more preferably H or methyl, in particular H.

[0114] Particularly preferred groups P are selected from the group consisting of CH.sub.2═CW.sup.1—CO—O—, in particular CH.sub.2═CH—CO—O—, CH.sub.2═C(CH.sub.3)—CO—O— and CH.sub.2═CF—CO—O—, furthermore CH.sub.2═CH—O—, (CH.sub.2═CH).sub.2CH—O—CO—, (CH.sub.2═CH).sub.2CH—O—,

##STR00021##

or a group

##STR00022## [0115] Y denotes H or methyl, in particular H.

[0116] Very particularly preferred groups P are selected from the group consisting of acrylate, methacrylate, fluoroacrylate, furthermore vinyloxy, chloroacrylate, oxetane, epoxide groups and a group,

##STR00023##

[0117] Y denotes H or methyl, in particular H, and of these preferably an acrylate or methacrylate group or a group,

##STR00024##

wherein Y denotes H or methyl.

[0118] The compounds of formula I are preferably selected from compounds of the sub-formulae I-1 to I-9,

##STR00025##

wherein R.sup.11, R.sup.21, A.sup.11, X.sup.11, X.sup.21, Y.sup.11, Y.sup.12, Sp.sup.11, and Sp.sup.21 have one of the meanings as given above in formula I, A.sup.12 to A.sup.23 have one of the meanings for A in formula I, A.sup.11 has one of the meanings as given above under formula I, and Z.sup.11 to Z.sup.22 have one of the meanings for Z as given above under formula I.

[0119] Further preferred compounds of formula I-1 are selected from the compounds of formulae I-1-1 to I-1-3,

##STR00026##

wherein R.sup.11, R.sup.21, A.sup.11, X.sup.11, X.sup.21, Sp.sup.11, and Sp.sup.21 have one of the meanings as given above in formula I, A.sup.21 has one of the meanings for A in formula I, preferably A.sup.21 denotes a group consisting of 1,4-phenylene, wherein, in addition, one or two CH groups may be replaced by N and wherein, in addition, one or more H atoms may be replaced by L as given above under formula I, or a group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, wherein, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by —O— and/or —S— and wherein, in addition, one or more H atoms may be replaced by F.

[0120] Preferred compounds of formula I-2 are selected from the following sub formula I-2-1 to I-2-3:

##STR00027##

wherein R.sup.11, R.sup.21, X.sup.11, X.sup.21, Sp.sup.11 and Sp.sup.21 have one of the meanings as given above in formula I, and Z.sup.11 has one of the meanings for Z as given above under formula I, A.sup.12, A.sup.21 have one of the meanings for A given above under formula I, preferably A.sup.12, A.sup.21 denote each and independently a group consisting of 1,4-phenylene, wherein, in addition, one or two CH groups may be replaced by N and wherein, in addition, one or more H atoms may be replaced by L as given above under formula I, or a group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, wherein, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by —O— and/or —S— and wherein, in addition, one or more H atoms may be replaced by F.

[0121] Preferred compounds of formula I-3 are selected from the following subformulae I-3-1 to I-3-3,

##STR00028##

wherein R.sup.11, R.sup.21, X.sup.11, X.sup.21, Sp.sup.11 and Sp.sup.21 have one of the meanings as given above in formula I, Z.sup.21 has one of the meanings for Z as given above under formula I, A.sup.21 and A.sup.22 have one of the meanings for A as given above under formula I. Preferably A.sup.21 and A.sup.22 denote each and independently a group consisting of 1,4-phenylene, wherein, in addition, one or two CH groups may be replaced by N and wherein, in addition, one or more H atoms may be replaced by L as given above under formula I, or a group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, wherein, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by —O— and/or —S— and wherein, in addition, one or more H atoms may be replaced by F.

[0122] Preferred compounds of formula I-4 are selected from the following subformulae,

##STR00029##

wherein R.sup.11, R.sup.21, X.sup.11, X.sup.21, Sp.sup.11 and Sp.sup.21 have one of the meanings as given above in formula I, A.sup.12, A.sup.21 and A.sup.22 have one of the meanings for A as given above under formula I, Z.sup.11, and Z.sup.21 have one of the meanings for Z as given above under formula I, r and q denote 1, 2 or 3, s denotes an integer from 1 to 6, and A.sup.12, A.sup.21 and A.sup.22 have one of the meanings for A s given above under formula I. Preferably A.sup.12, A.sup.21 and A.sup.22 denote each and independently a group consisting of 1,4-phenylene, wherein one or two CH groups may be replaced by N and wherein, in addition, one or more H atoms may be replaced by L as given above under formula I, or a group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, wherein, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by —O— and/or —S— and wherein, in addition, one or more H atoms may be replaced by F.

[0123] Preferred compounds of formula I-5 are selected from the following sub formula,

##STR00030##

wherein R.sup.11, R.sup.21, X.sup.11, X.sup.21, Sp.sup.11 and Sp.sup.21 have one of the meanings as given above in formula I, Z.sup.1, Z.sup.12 and Z.sup.21 have one of the meanings for Z as given above under formula I, and A.sup.12, A.sup.13, A.sup.21 and A.sup.22 have one of the meanings for A as given above under formula I. Preferably, A.sup.12, A.sup.13, A.sup.21 and A.sup.22 denote each and independently a group consisting of 1,4-phenylene, wherein one or two CH groups may be replaced by N and wherein, in addition, one or more H atoms may be replaced by L as given above under formula I, or a group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, wherein, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by —O— and/or —S— and wherein, in addition, one or more H atoms may be replaced by F.

[0124] Preferred compounds of formula I-2-1 are compounds of the following sub-formula,

##STR00031##

wherein R.sup.11, R.sup.21, X.sup.11, X.sup.21, Sp.sup.11 and Sp.sup.21 have one of the meanings as given above in formula I, Z.sup.11 has one of the meanings for Z as given above under formula I, and
the group

##STR00032##

is each and independently

##STR00033##

or denotes

##STR00034##

furthermore

##STR00035##

wherein L have one of the meanings as given above in formula I, and preferably denotes F, Cl, OCH.sub.3, COCH.sub.3 or alkyl having 1 to 6 C Atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or X.sup.21—Sp.sup.21-R.sup.21.

[0125] Preferred compounds of formulae I-3-1 to I-3-3 are compounds of the following sub-formulae:

##STR00036##

##STR00037##

is each and independently

##STR00038##

or denotes

##STR00039##

furthermore

##STR00040##

wherein L have one of the meanings as given above in formula I, and preferably is F, Cl, OCH.sub.3, COCH.sub.3 or alkyl having 1 to 6 C Atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or X.sup.21—Sp.sup.21-R.sup.21.

[0126] Preferred compounds of formulae I-4-1 are compounds of the following sub-formula:

##STR00041##

wherein R.sup.11, R.sup.21, X.sup.11, X.sup.21, Sp.sup.11 and Sp.sup.21 have one of the meanings as given above in formula I, Z.sup.11 and Z.sup.21 has one of the meanings for Z as given above under formula I, r and q denote 1, 2 or 3 and s denotes an integer from 1 to 6, and
the group

##STR00042##

is each and independently

##STR00043##

or denotes

##STR00044##

furthermore

##STR00045##

wherein L have one of the meanings as given above in formula I, and preferably F, Cl, OCH.sub.3, COCH.sub.3 or alkyl having 1 to 6 C Atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or X.sup.21—Sp.sup.21-R.sup.21.

[0127] Preferred compounds of formulae I-5-1 are compounds of the following sub-formula:

##STR00046##

wherein R.sup.11, R.sup.21, X.sup.11, X.sup.21, Sp.sup.11 and Sp.sup.21 have one of the meanings as given above in formula I, Z.sup.11, Z.sup.12 and Z.sup.21 has each and independently one of the meanings for Z as given above under formula I, r and q denote 1, 2 or 3 and s denotes an integer from 1 to 6, and
the group

##STR00047##

is each and independently

##STR00048##

or denotes

##STR00049##

furthermore

##STR00050##

wherein L have one of the meanings as given above in formula I, and preferably is F, Cl, OCH.sub.3, COCH.sub.3 or alkyl having 1 to 6 C Atoms, such as, methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or X.sup.21—Sp.sup.21-R.sup.21.

[0128] Further preferred compounds of formula I-2-1a are compounds of the following sub-formula:

##STR00051##

wherein R.sup.11, R.sup.21, X.sup.11, X.sup.21, Sp.sup.11 and Sp.sup.21 have one of the meanings as given above in formula I, and L denotes F, Cl, OCH.sub.3, COCH.sub.3 or alkyl having 1 to 6 C Atoms, such as, methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or X.sup.21—Sp.sup.21-R.sup.21.

[0129] Further preferred compounds of formulae I-3-1a to I-3-1c are compounds of the following sub-formulae:

##STR00052##

[0130] Further preferred compounds of formulae I-4-1 are compounds of the following sub-formulae:

##STR00053##

[0131] Further preferred compounds of formulae I-5-1 are compounds of the following sub-formulae:

##STR00054## ##STR00055##

[0132] Further preferred compounds of formula I-2-1a are compounds of the following sub-formula:

##STR00056## ##STR00057## ##STR00058## ##STR00059##

wherein [0133] X denotes each and independently methyl or H, preferably methyl [0134] Y denotes methyl or H, [0135] Sp.sup.11 and Sp.sup.21 have one of the meanings as given above in formula I, and preferably denote each and independently preferably alkylene having 1 to 20, preferably 1 to 12, C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, [0136] more preferably straight-chain ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, and [0137] L denotes F, Cl, OCH.sub.3 and COCH.sub.3 or alkylene having 1 to 6 C Atoms, preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl.

[0138] Further preferred compounds of formula I-3-1a to I-3-1c are compounds of the following sub-formula:

##STR00060## ##STR00061## ##STR00062## ##STR00063## ##STR00064## ##STR00065##

wherein [0139] X denotes each and independently methyl or H, preferably methyl [0140] Y denotes methyl or H, [0141] Sp.sup.11 and Sp.sup.21 have one of the meanings as given above in formula I, and preferably denote each and independently preferably alkylene having 1 to 20, preferably 1 to 12, C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, [0142] more preferably straight-chain ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, and [0143] L denotes F, Cl, OCH.sub.3 and COCH.sub.3 or alkylene having 1 to 6 C Atoms, preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl.

[0144] Further preferred compounds of formulae I-4-1 are compounds of the following sub-formulae:

##STR00066## ##STR00067## ##STR00068## ##STR00069## ##STR00070##

wherein [0145] X denotes each and independently methyl or H, preferably methyl [0146] Y denotes methyl or H, [0147] Sp.sup.11 and Sp.sup.21 have one of the meanings as given above in formula I, and preferably denote each and independently alkylene having 1 to 20, preferably 1 to 12, C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, [0148] more preferably straight-chain ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, and [0149] L denotes F, Cl, OCH.sub.3 and COCH.sub.3 or alkylene having 1 to 6 C Atoms, preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl.

[0150] Further preferred compounds of formulae I-5-1 are compounds of the following sub-formulae:

##STR00071## ##STR00072## ##STR00073## ##STR00074## ##STR00075## ##STR00076## ##STR00077##

wherein [0151] x denotes each and independently methyl or H, preferably methyl [0152] Y denotes methyl or H, [0153] Sp.sup.11 and Sp.sup.21 have one of the meanings as given above in formula I, and preferably denote each and independently, alkylene having 1 to 20, preferably 1 to 12, C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, [0154] more preferably straight-chain ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, and L denotes F, Cl, OCH.sub.3 and COCH.sub.3 or alkylene having 1 to 6 C Atoms, preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl.

[0155] The compounds of formula I and subformulae thereof are preferably synthesised according to or in analogy to the procedures described in WO 2017/102068 and JP 2006-6232809:

[0156] The media according to the invention preferably comprise from 0.01 to 10%, particularly preferably from 0.05 to 5% and most preferably from 0.1 to 3% of component A) comprising compounds of formula I according to the invention.

[0157] The media preferably comprise one, two or three, more preferably one or two and most preferably one compound of the formula I according to the invention.

[0158] In a preferred embodiment component A) consists of compounds of formula I.

[0159] In a preferred embodiment, the LC-host mixture (component B) according to the present invention comprises one or more, preferably two or more, low-molecular-weight (i.e. monomeric or unpolymerized) compounds. The latter are stable or unreactive with respect to a polymerisation reaction or photoalignment under the conditions used for the polymerisation of the polymerizable compounds or photoalignment of the photoreactive mesogen of formula I.

[0160] In principle, a suitable host mixture is any dielectrically negative or positive LC mixture which is suitable for use in conventional VA, IPS or FFS displays.

[0161] Suitable LC mixtures are known to the person skilled in the art and are described in the literature. LC media for VA displays having negative dielectric anisotropy are described in for example EP 1378557 A1.

[0162] Suitable LC mixtures having positive dielectric anisotropy which are suitable for LCDs and especially for IPS displays are known, for example, from JP 07-181439 (A), EP 0667555, EP 0673986, DE 19509410, DE 19528106, DE 19528107, WO 96/23851, WO 96/28521 and WO2012/079676.

[0163] Preferred embodiments of the liquid-crystalline medium having negative or positive dielectric anisotropy according to the invention are indicated below and explained in more detail by means of the working examples.

[0164] The LC host mixture is preferably a nematic LC mixture, and preferably does not have a chiral LC phase.

[0165] In a preferred embodiment of the present invention the LC medium contains an LC host mixture with negative dielectric anisotropy. Preferred embodiments of such an LC medium, and the corresponding LC host mixture, are those of sections a)-z) below: [0166] a) LC medium which comprises one or more compounds of the formulae CY and/or PY:

##STR00078## [0167] wherein [0168] a denotes 1 or 2, [0169] b denotes 0 or 1,

##STR00079##

denotes

##STR00080## [0170] R.sup.1 and R.sup.2 each, independently of one another, denote 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, preferably alkyl or alkoxy having 1 to 6 C atoms, [0171] Z.sup.x and Z.sup.y each, independently of one another, denote —CH.sub.2CH.sub.2—, —CH═CH—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —CO—O—, —O—CO—, —C.sub.2F.sub.4—, —CF═CF—, —CH═CH—CH.sub.2O— or a single bond, preferably a single bond, [0172] L.sup.1-4 each, independently of one another, denote F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F, CHF.sub.2. [0173] Preferably, both L.sup.1 and L.sup.2 denote F or one of L.sup.1 and L.sup.2 denotes F and the other denotes Cl, or both L.sup.3 and L.sup.4 denote F or one of L.sup.3 and L.sup.4 denotes F and the other denotes Cl. [0174] The compounds of the formula CY are preferably selected from the group consisting of the following sub-formulae:

##STR00081## ##STR00082## ##STR00083## ##STR00084## [0175] wherein a denotes 1 or 2, alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, and (O) denotes an oxygen atom or a single bond. Alkenyl preferably denotes CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. [0176] The compounds of the formula PY are preferably selected from the group consisting of the following sub-formulae:

##STR00085## ##STR00086## ##STR00087## [0177] wherein alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, and (0) denotes an oxygen atom or a single bond. Alkenyl preferably denotes CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. [0178] b) LC medium which additionally comprises one or more compounds of the following formula:

##STR00088## [0179] in which the individual radicals have the following meanings:

##STR00089## denotes

##STR00090## denotes

##STR00091## [0180] R.sup.3 and R.sup.4 each, independently of one another, denote alkyl having 1 to 12 C atoms, in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced [0181] by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in such a way that O atoms are not linked directly to one another, [0182] Z.sup.y [0183] denotes —CH.sub.2CH.sub.2—, —CH═CH—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —OCH.sub.2—, —CO—O—, —O—CO—, —C.sub.2F.sub.4—, —CF═CF—, —CH═CH—CH.sub.2O— or a single bond, preferably a single bond. [0184] The compounds of the formula ZK are preferably selected from the group consisting of the following sub-formulae:

##STR00092## [0185] in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms. Alkenyl preferably denotes CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. [0186] Especially preferred are compounds of formula ZK1 and ZK3. [0187] Particularly preferred compounds of formula ZK are selected from the following sub-formulae:

##STR00093## [0188] wherein the propyl, butyl and pentyl groups are straight-chain groups. [0189] Most preferred are compounds of formula ZK1a and ZK3a. [0190] c) LC medium which additionally comprises one or more compounds of the following formula:

##STR00094## [0191] in which the individual radicals on each occurrence, identically or differently, have the following meanings: [0192] R.sup.5 and R.sup.6 each, independently of one another, denote alkyl having 1 to 12 C atoms, where, in addition, one or two non-adjacent CH.sub.2 groups may be replaced [0193] by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, preferably alkyl or alkoxy having 1 to 6 C atoms, denotes or

##STR00095##

denotes

##STR00096##

denotes

##STR00097##

and [0194] e denotes 1 or 2. [0195] The compounds of the formula DK are preferably selected from the group consisting of the following sub-formulae:

##STR00098## ##STR00099## [0196] in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms. Alkenyl preferably denotes CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. [0197] d) LC medium which additionally comprises one or more compounds of the following formula:

##STR00100## [0198] in which the individual radicals have the following meanings:

##STR00101##

denotes

##STR00102## [0199] with at least one ring F being different from cyclohexylene, [0200] f denotes 1 or 2, [0201] R.sup.1 and R.sup.2 each, independently of one another, denote 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, [0202] Z.sup.x [0203] denotes —CH.sub.2CH.sub.2—, —CH═CH—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2O—, —O—CH.sub.2—, —CO—O—, —O—CO—, —C.sub.2F.sub.4—, —CF═CF—, —CH═CH—CH.sub.2O— or a single bond, preferably a single bond, [0204] L.sup.1 and L.sup.2 each, independently of one another, denote F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F, CHF.sub.2. [0205] Preferably, both radicals L.sup.1 and L.sup.2 denote F or one of the radicals L.sup.1 and L.sup.2 denotes F and the other denotes Cl. [0206] The compounds of the formula LY are preferably selected from the group consisting of the following sub-formulae:

##STR00103## ##STR00104## ##STR00105## [0207] in which R.sup.1 has the meaning indicated above, alkyl denotes a straight-chain alkyl radical having 1-6 C atoms, (O) denotes an oxygen atom or a single bond, and v denotes an integer from 1 to 6. R.sup.1 preferably denotes straight-chain alkyl having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms, in particular CH.sub.3, C.sub.2H.sub.5, n-C.sub.3H.sub.7, n-C.sub.4H.sub.9, n-C.sub.5H.sub.11, CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. [0208] e) LC medium which additionally comprises one or more compounds selected from the group consisting of the following formulae:

##STR00106## [0209] in which alkyl denotes C.sub.1-6-alkyl, L.sup.x denotes H or F, and X denotes F, Cl, OCF.sub.3, OCHF.sub.2 or OCH═CF.sub.2. Particular preference is given to compounds of the formula G1 in which X denotes F. [0210] f) LC medium which additionally comprises one or more compounds selected from the group consisting of the following formulae:

##STR00107## ##STR00108## [0211] in which R.sup.5 has one of the meanings indicated above for R.sup.1, alkyl denotes C.sub.1-6-alkyl, d denotes 0 or 1, and z and m each, independently of one another, denote an integer from 1 to 6. R.sup.5 in these compounds is particularly preferably C.sub.1-6-alkyl or -alkoxy or C.sub.2-6-alkenyl, d is preferably 1. The LC medium according to the invention preferably comprises one or more compounds of the above-mentioned formulae in amounts of ≥5% by weight. [0212] g) LC medium which additionally comprises one or more biphenyl compounds selected from the group consisting of the following formulae:

##STR00109## [0213] in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms. Alkenyl and alkenyl* preferably denote CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. [0214] The proportion of the biphenyls of the formulae B1 to B3 in the LC mixture is preferably at least 3% by weight, in particular ≥5% by weight. [0215] The compounds of the formula B2 are particularly preferred. [0216] The compounds of the formulae B1 to B3 are preferably selected from the group consisting of the following sub-formulae:

##STR00110## [0217] in which alkyl* denotes an alkyl radical having 1-6 C atoms. The medium according to the invention particularly preferably comprises one or more compounds of the formulae B1a and/or B2e. [0218] h) LC medium which additionally comprises one or more terphenyl compounds of the following formula:

##STR00111## [0219] in which R.sup.5 and R.sup.6 each, independently of one another, have one of the meanings indicated above, and

##STR00112## [0220] each, independently of one another, denote

##STR00113## [0221] in which L.sup.5 denotes F or Cl, preferably F, and L.sup.6 denotes F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F or CHF.sub.2, preferably F. [0222] The compounds of the formula T are preferably selected from the group consisting of the following sub-formulae:

##STR00114## ##STR00115## ##STR00116## ##STR00117## [0223] in which R denotes a straight-chain alkyl or alkoxy radical having 1-7 C atoms, R* denotes a straight-chain alkenyl radical having 2-7 C atoms, (O) denotes an oxygen atom or a single bond, and m denotes an integer from 1 to 6. R* preferably denotes CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. [0224] R preferably denotes methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentoxy. [0225] The LC medium according to the invention preferably comprises the terphenyls of the formula T and the preferred sub-formulae thereof in an amount of 0.5-30% by weight, in particular 1-20% by weight. [0226] Particular preference is given to compounds of the formulae T1, T2, T3 and T21. In these compounds, R preferably denotes alkyl, furthermore alkoxy, each having 1-5 C atoms. [0227] The terphenyls are preferably employed in mixtures according to the invention if the Δn value of the mixture is to be 0.1. Preferred mixtures comprise 2-20% by weight of one or more terphenyl compounds of the formula T, preferably selected from the group of compounds T1 to T22. [0228] i) LC medium which additionally comprises one or more compounds selected from the group consisting of the following formulae:

##STR00118## ##STR00119## [0229] in which R.sup.1 and R.sup.2 have the meanings indicated above and preferably each, independently of one another, denote straight-chain alkyl having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms. [0230] Preferred media comprise one or more compounds selected from the formulae O1, O3 and O4. [0231] k) LC medium which additionally comprises one or more compounds of the following formula:

##STR00120## [0232] in which [0233] denotes

##STR00121## [0234] R.sup.9 denotes H, CH.sub.3, C.sub.2H.sub.5 or n-C.sub.3H.sub.7, (F) denotes an optional fluorine substituent, and q denotes 1, 2 or 3, and R.sup.7 has one of the meanings indicated for R.sup.1, preferably in amounts of >3% by weight, in particular ≥5% by weight and very particularly preferably 5-30% by weight. [0235] Particularly preferred compounds of the formula FI are selected from the group consisting of the following sub-formulae:

##STR00122##

in which R.sup.7 preferably denotes straight-chain alkyl, and R.sup.9 denotes CH.sub.3, C.sub.2H.sub.5 or n-C.sub.3H.sub.7. Particular preference is given to the compounds of the formulae FI1, FI2 and FI3. [0236] l) LC medium which additionally comprises one or more compounds selected from the group consisting of the following formulae:

##STR00123## [0237] in which R.sup.8 has the meaning indicated for R.sup.1, and alkyl denotes a straight-chain alkyl radical having 1-6 C atoms. [0238] m) LC medium which additionally comprises one or more compounds which contain a tetrahydronaphthyl or naphthyl unit, such as, for example, the compounds selected from the group consisting of the following formulae:

##STR00124## ##STR00125## [0239] in which [0240] R.sup.10 and R.sup.11 each, independently of one another, denote 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, preferably alkyl or alkoxy having 1 to 6 C atoms, [0241] and R.sup.10 and R.sup.11 preferably denote straight-chain alkyl or alkoxy having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms, and [0242] Z.sup.1 and Z.sup.2 each, independently of one another, [0243] denote —C.sub.2H.sub.4—, —CH═CH—, —(CH.sub.2).sub.4—, —(CH.sub.2).sub.30—, —O(CH.sub.2).sub.3—, —CH═CH—CH.sub.2CH.sub.2—, —CH.sub.2CH.sub.2CH═CH—, —CH.sub.2O—, —OCH.sub.2—, —COO—, —O—CO—, —C.sub.2F.sub.4—, —CF═CF—, —CF═CH—, —CH═CF—, —CH.sub.2— or a single bond. [0244] n) LC medium which additionally comprises one or more difluorodibenzochromans and/or chromans of the following formulae:

##STR00126## [0245] in which [0246] R.sup.11 and R.sup.12 each, independently of one another, have one of the meanings indicated above for R.sup.11 under formula N1 [0247] ring M is trans-1,4-cyclohexylene or 1,4-phenylene, [0248] Z.sup.m —C.sub.2H.sub.4—, —CH.sub.2O—, —OCH.sub.2—, —CO—O— or —O—CO—, [0249] c is 0, 1 or 2, [0250] preferably in amounts of 3 to 20% by weight, in particular in amounts of 3 to 15% by weight. [0251] Particularly preferred compounds of the formulae BC, CR and RC are selected from the group consisting of the following sub-formulae:

##STR00127## ##STR00128## ##STR00129## [0252] in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, (O) denotes an oxygen atom or a single bond, c is 1 or 2, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms. Alkenyl and alkenyl* preferably denote CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. [0253] Very particular preference is given to mixtures comprising one, two or three compounds of the formula BC-2. [0254] o) LC medium which additionally comprises one or more fluorinated phenanthrenes and/or dibenzofurans of the following formulae:

##STR00130## [0255] in which R.sup.11 and R.sup.12 each, independently of one another, have one of the meanings indicated above for R.sup.11 under formula N1, b denotes 0 or 1, L denotes F, and r denotes 1, 2 or 3. [0256] Particularly preferred compounds of the formulae PH and BF are selected from the group consisting of the following sub-formulae:

##STR00131## [0257] in which R and R′ each, independently of one another, denote a straight-chain alkyl or alkoxy radical having 1-7 C atoms. [0258] p) LC medium which additionally comprises one or more monocyclic compounds of the following formula

##STR00132## [0259] wherein [0260] R.sup.1 and R.sup.2 each, independently of one another, denote alkyl having 1 to 12 C atoms, where, in addition, one or two non-adjacent CH.sub.2 groups may be replaced [0261] by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, preferably alkyl or alkoxy having 1 to 6 C atoms, [0262] L.sup.1 and L.sup.2 each, independently of one another, denote F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F, CHF.sub.2. [0263] Preferably, both L.sup.1 and L.sup.2 denote F or one of L.sup.1 and L.sup.2 denotes F and the other denotes Cl, [0264] The compounds of the formula Y are preferably selected from the group consisting of the following sub-formulae:

##STR00133## ##STR00134## [0265] in which, Alkyl and Alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, Alkoxy denotes a straight-chain alkoxy radical having 1-6 C atoms, Alkenyl and Alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms, and O denotes an oxygen atom or a single bond. Alkenyl and Alkenyl* preferably denote CH.sub.2═CH—, CH.sub.2═CHCH.sub.2CH.sub.2—, CH.sub.3—CH═CH—, CH.sub.3—CH.sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.2—CH═CH—, CH.sub.3—(CH.sub.2).sub.3—CH═CH— or CH.sub.3—CH═CH—(CH.sub.2).sub.2—. [0266] Particularly preferred compounds of the formula Y are selected from the group consisting of the following sub-formulae:

##STR00135## [0267] wherein Alkoxy preferably denotes straight-chain alkoxy with 3, 4, or 5 C atoms. [0268] q) LC medium which, apart from the stabilisers according to the invention, in particular of the formula I or sub-formulae thereof and the comonomers, comprises no compounds which contain a terminal vinyloxy group (—O—CH═CH.sub.2). [0269] r) LC medium which comprises 1 to 5, preferably 1, 2 or 3, stabilisers, preferably selected from stabilisers according to the invention, in particular of the formula I or sub-formulae thereof. [0270] s) LC medium in which the proportion of stabilisers, in particular of the formula I or sub-formulae thereof, in the mixture as a whole is 1 to 1500 ppm, preferably 100 to 1000 ppm. [0271] t) LC medium which comprises 1 to 8, preferably 1 to 5, compounds of the formulae CY1, CY2, PY1 and/or PY2. The proportion of these compounds in the mixture as a whole is preferably 5 to 60%, particularly preferably 10 to 35%. The content of these individual compounds is preferably in each case 2 to 20%. [0272] u) LC medium which comprises 1 to 8, preferably 1 to 5, compounds of the formulae CY9, CY10, PY9 and/or PY10. The proportion of these compounds in the mixture as a whole is preferably 5 to 60%, particularly preferably 10 to 35%. The content of these individual compounds is preferably in each case 2 to 20%. [0273] v) LC medium which comprises 1 to 10, preferably 1 to 8, compounds of the formula ZK, in particular compounds of the formulae ZK1, ZK2 and/or ZK6. The proportion of these compounds in the mixture as a whole is preferably 3 to 25%, particularly preferably 5 to 45%. The content of these individual compounds is preferably in each case 2 to 20%. [0274] w) LC medium in which the proportion of compounds of the formulae CY, PY and ZK in the mixture as a whole is greater than 70%, preferably greater than 80%. [0275] x) LC medium in which the LC host mixture contains one or more compounds containing an alkenyl group, preferably selected from the group consisting of formula CY, PY and LY, wherein one or both of R.sup.1 and R.sup.2 denote straight-chain alkenyl having 2-6 C atoms, formula ZK and DK, wherein one or both of R.sup.3 and R.sup.4 or one or both of R.sup.5 and R.sup.6 denote straight-chain alkenyl having 2-6 C atoms, and formula B2 and B3, very preferably selected from formulae CY15, CY16, CY24, CY32, PY15, PY16, ZK3, ZK4, DK3, DK6, B2 and B3, most preferably selected from formulae ZK3, ZK4, B2 and B3. The concentration of these compounds in the LC host mixture is preferably from 2 to 70%, very preferably from 3 to 55%. [0276] y) LC medium which contains one or more, preferably 1 to 5, compounds selected of formula PY1-PY8, very preferably of formula PY2. The proportion of these compounds in the mixture as a whole is preferably 1 to 30%, particularly preferably 2 to 20%. The content of these individual compounds is preferably in each case 1 to 20%. [0277] z) LC medium which contains one or more, preferably 1, 2 or 3, compounds of formula T2. The content of these compounds in the mixture as a whole is preferably 1 to 20%.

[0278] In another preferred embodiment of the present invention the LC medium contains an LC host mixture with positive dielectric anisotropy. Preferred embodiments of such an LC medium, and the corresponding LC host mixture, are those of sections aa)-mmm) below: [0279] aa) LC-medium, characterised in that it comprises one or more compounds selected from the group of compounds of the formulae II and III

##STR00136## [0280] wherein [0281] R.sup.20 each, identically or differently, denote a halogenated or unsubstituted 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—,

##STR00137## —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, [0282] X.sup.20 each, identically or differently, denote F, Cl, CN, SF.sub.5, SCN, NCS, a halogenated alkyl radical, a halogenated alkenyl radical, a halogenated alkoxy radical or a halogenated alkenyloxy radical, each having up to 6 C atoms, and [0283] Y.sup.20-24 each, identically or differently, denote H or F; [0284] W denotes H or methyl,

##STR00138## each, independently of one another, denote

##STR00139## [0285] The compounds of the formula II are preferably selected from the following formulae:

##STR00140## [0286] wherein R.sup.20 and X.sup.20 have the meanings indicated above. [0287] R.sup.20 preferably denotes alkyl having 1 to 6 C atoms. X.sup.20 preferably denotes F. Particular preference is given to compounds of the formulae IIa and IIb, in particular compounds of the formulae IIa and IIb wherein X denotes F. [0288] The compounds of the formula III are preferably selected from the following formulae:

##STR00141## [0289] wherein R.sup.20 and X.sup.20 have the meanings indicated above. [0290] R.sup.20 preferably denotes alkyl having 1 to 6 C atoms. X.sup.20 preferably denotes F. Particular preference is given to compounds of the formulae IIIa and IIIe, in particular compounds of the formula IIIa; [0291] bb) LC-medium additionally comprising one or more compounds selected from the following formulae:

##STR00142## [0292] wherein [0293] R.sup.20, X.sup.20, W and Y.sup.20-23 have the meanings indicated above under formula II, and [0294] Z.sup.20 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— or —OCF.sub.2—, in formulae V and VI also a single bond, in formulae V and VIII also —CF.sub.2O—, [0295] r denotes 0 or 1, and [0296] s denotes 0 or 1; [0297] The compounds of the formula IV are preferably selected from the following formulae:

##STR00143## [0298] wherein R.sup.20 and X.sup.20 have the meanings indicated above. [0299] R.sup.20 preferably denotes alkyl having 1 to 6 C atoms. X.sup.20 preferably denotes F or OCF.sub.3, furthermore OCF═CF.sub.2 or C.sub.1; [0300] The compounds of the formula V are preferably selected from the following formulae:

##STR00144## ##STR00145## [0301] wherein R.sup.20 and X.sup.20 have the meanings indicated above. [0302] R.sup.20 preferably denotes alkyl having 1 to 6 C atoms. X.sup.20 preferably denotes F and OCF.sub.3, furthermore OCHF.sub.2, CF.sub.3, OCF═CF.sub.2 and OCH═CF.sub.2; [0303] The compounds of the formula VI are preferably selected from the following formulae:

##STR00146## [0304] wherein R.sup.20 and X.sup.20 have the meanings indicated above. [0305] R.sup.20 preferably denotes alkyl having 1 to 6 C atoms. X.sup.20 preferably denotes F, furthermore OCF.sub.3, CF.sub.3, CF═CF.sub.2, OCHF.sub.2 and OCH═CF.sub.2; [0306] The compounds of the formula VII are preferably selected from the following formulae:

##STR00147## [0307] wherein R.sup.20 and X.sup.20 have the meanings indicated above. [0308] R.sup.20 preferably denotes alkyl having 1 to 6 C atoms. X.sup.20 preferably denotes F, furthermore OCF.sub.3, OCHF.sub.2 and OCH═CF.sub.2. [0309] cc) The medium additionally comprises one or more compounds selected from the formulae ZK1 to ZK10 given above. Especially preferred are compounds of formula ZK1 and ZK3. Particularly preferred compounds of formula ZK are selected from the subformulae ZK1a, ZK1b, ZK1c, ZK3a, ZK3b, ZK3c and ZK3d. [0310] dd) The medium additionally comprises one or more compounds selected from the formulae DK1 to DK12 given above. Especially preferred compounds are DK3. [0311] ee) The medium additionally comprises one or more compounds selected from the following formulae:

##STR00148## [0312] wherein X.sup.20 has the meanings indicated above, and

TABLE-US-00001 L denotes H or F, “alkenyl” denotes C.sub.2-6-alkenyl [0313] ff) The compounds of the formulae DK-3a and IX are preferably selected from the following formulae:

##STR00149## [0314] wherein “alkyl” denotes C.sub.1-6-alkyl, preferably n-C.sub.3H.sub.7, n-C.sub.4H.sub.9 or n-C.sub.5H.sub.11, in particular n-C.sub.3H.sub.7. [0315] gg) The medium additionally comprises one or more compounds selected from the formulae B1, B2 and B3 given above, preferably from the formula B2. The compounds of the formulae B1 to B3 are particularly preferably selected from the formulae B1a, B2a, B2b and B2c. [0316] hh) The medium additionally comprises one or more compounds selected from the following formula:

##STR00150## [0317] wherein L.sup.20 denotes H or F, and R.sup.21 and R.sup.22 each, identically or differently, denote n-alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms, and preferably each, identically or differently, denote alkyl having 1 to 6 C atoms. [0318] ii) The medium comprises one or more compounds of the following formulae:

##STR00151## [0319] Wherein W, R.sup.20, X.sup.20 and Y.sup.20-23 have the meanings indicated in formula III, and

##STR00152##

each, independently of one another, denote

##STR00153##

and

##STR00154##

denotes

##STR00155## [0320] The compounds of the formulae XI and XII are preferably selected from the following formulae:

##STR00156## ##STR00157## [0321] wherein R.sup.20 and X.sup.20 have the meaning indicated above and preferably R.sup.20 denotes alkyl having 1 to 6 C atoms and X.sup.20 denotes F. [0322] The mixture according to the invention particularly preferably comprises at least one compound of the formula XIIa and/or XIIe. [0323] jj) The medium comprises one or more compounds of formula T given above, preferably selected from the group of compounds of the formulae T21 to T23 and T25 to T27. [0324] Particular preference is given to the compounds of the formulae T21 to T23. Very particular preference is given to the compounds of the formulae

##STR00158## [0325] kk) The medium comprises one or more compounds selected from the group of formulae DK9, DK10 and DK11 given above. [0326] ll) The medium additionally comprises one or more compounds selected from the following formulae:

##STR00159## [0327] wherein R.sup.20 and X.sup.20 each, independently of one another, have one of the meanings indicated above, and Y.sup.20-23 each, independently of one another, denote H or F. X.sup.20 is preferably F, Cl, CF.sub.3, OCF.sub.3 or OCHF.sub.2. R.sup.20 preferably denotes alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms. [0328] The mixture according to the invention particularly preferably comprises one or more compounds of the formula XVIII-a,

##STR00160## [0329] wherein R.sup.20 has the meanings indicated above. R.sup.20 preferably denotes straight-chain alkyl, in particular ethyl, n-propyl, n-butyl and n-pentyl and very particularly preferably n-propyl. The compound(s) of the formula XVIII, in particular of the formula XVIII-a, is (are) preferably employed in the mixtures according to the invention in amounts of 0.5-20% by weight, particularly preferably 1-15% by weight. [0330] mm) The medium additionally comprises one or more compounds of the formula XIX,

##STR00161## [0331] wherein R.sup.20, X.sup.20 and Y.sup.20-25 have the meanings indicated in formula I, s denotes 0 or 1, and

##STR00162##

denotes

##STR00163## [0332] In the formula XIX, X.sup.20 may also denote an alkyl radical having 1-6 C atoms or an alkoxy radical having 1-6 C atoms. The alkyl or alkoxy radical is preferably straight-chain. [0333] R.sup.20 preferably denotes alkyl having 1 to 6 C atoms. X.sup.20 preferably denotes F; [0334] The compounds of the formula XIX are preferably selected from the following formulae:

##STR00164## ##STR00165## [0335] wherein R.sup.20, X.sup.20 and Y.sup.20 have the meanings indicated above. R.sup.20 preferably denotes alkyl having 1 to 6 C atoms. X.sup.20 preferably denotes F, and Y.sup.20 is preferably F;

##STR00166##

is preferably

##STR00167## ##STR00168## [0336] R.sup.20 is straight-chain alkyl or alkenyl having 2 to 6 C atoms; [0337] nn) The medium comprises one or more compounds of the formulae G1 to G4 given above, preferably selected from G1 and G2 wherein alkyl denotes C.sub.1-6-alkyl, L.sup.x denotes H and X denotes F or Cl. In G2, X particularly preferably denotes Cl. [0338] oo) The medium comprises one or more compounds of the following formulae:

##STR00169## [0339] wherein R.sup.20 and X.sup.20 have the meanings indicated above. R.sup.20 preferably denotes alkyl having 1 to 6 C atoms. X.sup.20 preferably denotes F. The medium according to the invention particularly preferably comprises one or more compounds of the formula XXII wherein X.sup.20 preferably denotes F. The compound(s) of the formulae XX-XXII is (are) preferably employed in the mixtures according to the invention in amounts of 1-20% by weight, particularly preferably 1-15% by weight. Particularly preferred mixtures comprise at least one compound of the formula XXII. [0340] pp) The medium comprises one or more compounds of the following pyrimidine or pyridine compounds of the formulae

##STR00170## [0341] wherein R.sup.20 and X.sup.20 have the meanings indicated above. R.sup.20 preferably denotes alkyl having 1 to 6 C atoms. X.sup.20 preferably denotes F. The medium according to the invention particularly preferably comprises one or more compounds of the formula M-1, wherein X.sup.20 preferably denotes F. The compound(s) of the formulae M-1-M-3 is (are) preferably employed in the mixtures according to the invention in amounts of 1-20% by weight, particularly preferably 1-15% by weight.

[0342] Further preferred embodiments are indicated below: [0343] qq) The medium comprises two or more compounds of the formula XII, in particular of the formula XIIe; [0344] rr) The medium comprises 2-30% by weight, preferably 3-20% by weight, particularly preferably 3-15% by weight, of compounds of the formula XII; [0345] ss) Besides the compounds of the formulae XII, the medium comprises further compounds selected from the group of the compounds of the formulae II, III, IX-XIII, XVII and XVIII; [0346] tt) The proportion of compounds of the formulae II, III, IX-XI, XIII, XVII and XVIII in the mixture as a whole is 40 to 95% by weight; [0347] uu) The medium comprises 10-50% by weight, particularly preferably 12-40% by weight, of compounds of the formulae and/or III; [0348] vv) The medium comprises 20-70% by weight, particularly preferably 25-65% by weight, of compounds of the formulae IX-XIII; [0349] ww) The medium comprises 4-30% by weight, particularly preferably 5-20% by weight, of compounds of the formula XVII; [0350] xx) The medium comprises 1-20% by weight, particularly preferably 2-15% by weight, of compounds of the formula XVIII; [0351] yy) The medium comprises at least two compounds of the formulae

##STR00171## [0352] zz) The medium comprises at least two compounds of the formulae

##STR00172## [0353] aaa) The medium comprises at least two compounds of the formula XIIa and at least two compounds of the formula XIIe. [0354] bbb) The medium comprises at least one compound of the formula XIIa and at least one compound of the formula XIe and at least one compound of the formula IIIa. [0355] ccc) The medium comprises at least two compounds of the formula XIIa and at least two compounds of the formula XIe and at least one compound of the formula IIIa. [0356] ddd) The medium comprises in total 25% by weight, preferably 30% by weight, of one or more compounds of the formula XII. [0357] eee) The medium comprises 20% by weight, preferably 24% by weight, preferably 25-60% by weight, of compounds of the formula ZK3, in particular the compound of the formula ZK3a,

##STR00173## [0358] fff) The medium comprises at least one compound selected from the group of compounds ZK3a, ZK3b and ZK3c, preferably ZK3a, in combination with compound ZK3d

##STR00174##

ggg) The medium comprises at least one compound of the formula DPGU-n-F. [0359] hhh) The medium comprises at least one compound of the formula CDUQU-n-F. [0360] iii) The medium comprises at least one compound of the formula CPU-n-OXF. [0361] jjj) The medium comprises at least one compound of the formula CPGU-3-OT. [0362] kkk) The medium comprises at least one compound of the formula PPGU-n-F. [0363] lll) The medium comprises at least one compound of the formula PGP-n-m, preferably two or three compounds. [0364] mmm) The medium comprises at least one compound of the formula PGP-2-2V having the structure

##STR00175##

[0365] In a preferred embodiment, the liquid crystal mixture according to the present invention further comprises a polymerizable component C) comprising one or more polymerizable compounds.

[0366] The polymerizable compounds can be selected from isotropic or mesogenic polymerizable compounds known to the skilled person in the art.

[0367] Preferably, the polymerizable component C) comprises one or more polymerizable compounds of formula P,

P.sup.a-Sp.sup.a-(A.sup.p).sub.n2-Sp.sup.b-P.sup.b P

wherein the individual radicals have the following meanings: [0368] P.sup.a, P.sup.b each, independently of one another, denote a polymerizable group, preferably each and independently selected from the group consisting of acrylate, methacrylate, ethacrylate, fluoroacrylate, vinyl¬oxy, chloro¬acry-late, oxetane, or epoxide groups [0369] Sp.sup.a, Sp.sup.b on each occurrence, identically or differently, denote a spacer group or a single bond, [0370] A.sup.p each and independently from another, in each occurrence, a group selected from 5, 6 or 7-membered alicyclic groups wherein, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by —NH—, —O— and/or —S—, wherein one or more non-adjacent —CH.sub.2—CH.sub.2— groups may be replaced by —CH═CH—, and wherein one or more H atoms may be replaced by F, [0371] preferably 5-membered groups such as cyclopentane, cyclopentane, tetrahydrofuran, tetrahydrothiofuran, pyrrolidine, or 6-membered groups, such as cyclohexane, silinane, cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dioxane, 1,3-dithiane, piperidine, or 7-membered groups, such as cycloheptane, trans-1,4-cyclohexylene, [0372] more preferably 1,4-cyclohexylene or 1,4-cyclohexenylene, [0373] n2 denotes 0, 1, 2 or 3, preferably 1 or 2.

[0374] Preferred spacer groups Sp.sup.a,b are selected from the formula Sp″-X″, so that the radicals P-Sp- and P.sup.a/b-Sp.sup.a/b- conforms to the formulae P-Sp″-X″— and P.sup.a/b-Sp″-X″—, respectively, wherein [0375] Sp″ denotes alkylene having 1 to 20, preferably 1 to 12, C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN and wherein, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced, independently of one another, by —O—, —S—, —NH—, —N(R.sup.0)—, —Si(R.sup.00R.sup.000)—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —S—CO—, —CO—S—, —N(R.sup.00)—CO—O—, —O—CO—N(R.sup.00)—, —N(R.sup.00)—CO—N(R.sup.00)—, —CH═CH— or —C≡C— in such a way that O and/or S atoms are not linked directly to one another, or a single bond, [0376] X″ denotes —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —CO—N(R.sup.00)—, —N(R.sup.00)—CO—, —N(R.sup.00)—CO—N(R.sup.00)—, —OCH.sub.2—, —CH.sub.2O—, —SCH.sub.2—, —CH.sub.2S—, —CF.sub.2O—, —OCF.sub.2—, —CF.sub.2S—, —SCF.sub.2—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —CF.sub.2CF.sub.2—, —CH═N—, —N═CH—, —N═N—, —CH═CR.sup.0—, —CY.sup.3═CY.sup.4—, —C≡C—, —CH═CH—CO—O—, —O—CO—CH═CH— or a single bond, preferably a singlebond [0377] R.sup.0, R.sup.00 [0378] and R.sup.000 each, independently of one another, denote H or alkyl having 1 to 12 C atoms, and [0379] Y.sup.3 and Y.sup.4 each, identically or differently, denote H, F, Cl or CN.

[0380] X″ is preferably —O—, —S—, —CO—, —C(O)O—, —OC(O)—, —O—C(O)O—, —CONR.sup.0—, —NR.sup.0—CO—, —NR.sup.0—CO—NR.sup.0— or a single bond.

[0381] Typical spacer groups Sp.sup.11 are, for example, a single bon, —(CH.sub.2).sub.p1—, —(CH.sub.2CH.sub.2O).sub.q1—CH.sub.2CH.sub.2—, —CH.sub.2CH.sub.2—S—CH.sub.2CH.sub.2—, —CH.sub.2CH.sub.2—NH—CH.sub.2CH.sub.2— or —(SiR.sup.00R.sup.000—O).sub.p1—, wherein p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R.sup.00 and R.sup.000 have the meanings indicated above.

[0382] Particularly preferred groups -Sp″-X″— are a single bond, —(CH.sub.2).sub.p1—, —(CH.sub.2).sub.p1—O—, —(CH.sub.2).sub.p1—O—CO—, —(CH.sub.2).sub.p1—O—CO—O—, wherein p1 and q1 have the meanings indicated above.

[0383] Particularly preferred groups Sp″ are, for example, in each case straight-chain methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethylene-N-methyliminoethylene, 1-methylalkylene, ethenylene, propenylene and butenylene.

[0384] Particularly preferred monomers of formula P are the following:

##STR00176##

[0385] If only a photoreactive component A) without any polymerizable component C) is utilized, a known issue with these materials is that they form layers that are very thin, in the region of 5-20 nm thickness. For some applications, such thin layers may not be sufficient to pass the stringent reliability tests required from display industry. Typically, these tests can include, but are not limited to, pressure or drop testing and/or heat stress. Such tests are regularly conducted for PI based alignment layers that in some cases have typically been subjected to a coating and two step heat curing process to give a thick (60-80 nm) layer with robust mechanical properties.

[0386] Another common test in the display industry is surface ‘hardness’. Whereby an abrasive object is moved across a surface in order to see if any deformation or visible damage is caused. Passing such a harness test is very difficult for thin layers since they are generally more susceptible to contact damage. In addition to hardness another consideration is long term reliability testing of parameters such as voltage holding ratio (VHR). Since surfactants and other chemicals are used in the glass cleaning process then there is a risk that these could ‘leak’ through the (photo)alignment layer during the lifetime of the product. This could result in a VHR drop and a visible reduction in display quality. In this regard, the utilization of a LC mixture comprising a photoreactive component A) comprising one or more compounds of formula I in combination with a polymerizable component C) comprising one or more compounds of formula P, exhibits significant advantages in terms of reliability issues than a LC mixture comprising a photoreactive component A) comprising one or more compounds of formula I taken alone, or even in combination with a polymerizable component C) comprising one or more polymerizable liquid crystalline compounds.

[0387] The amount of the polymerizable component C) in the LC mixture as a whole is preferably ranging from 0.1 to 5%, more preferably ranging from 0.3 to 3%, especially ranging from 0.5 to 2%.

[0388] The amount of one or more compounds of formula P in the polymerizable component C) as a whole is preferably ranging from 50 to 100%, more preferably ranging from 75 to 100%, especially ranging from 90 to 100%, in particular the polymerizable component C consists of one, two, three or more compounds of formula P.

[0389] The polymerizable compounds of formulae I and P are also suitable for polymerisation without an initiator, which is associated with considerable advantages, such as, for example, lower material costs and, in particular, reduced contamination of the LC medium by possible residual amounts of the initiator or degradation products thereof. The polymerisation can thus also be carried out without addition of an initiator. The LC medium thus, in a preferred embodiment, comprises no polymerisation initiator.

[0390] The polymerizable component C) or the LC medium as a whole may also comprise one or more stabilisers in order to prevent undesired spontaneous polymerisation of the RMs, for example during storage or transport. Suitable types and amounts of stabilisers are known to the person skilled in the art and are described in the literature. Particularly suitable are, for example, the commercially available stabilisers from the Irganox® series (BASF SE), such as, for example, Irganox® 1076. If stabilisers are employed, their proportion, based on the total amount of the RMs or the polymerizable component, is preferably 10-10,000 ppm, particularly preferably 50-1000 ppm.

[0391] The media according to the invention preferably comprise from 0.01 to 10%, particularly preferably from 0.05 to 7.5% and most preferably from 0.1 to 5% of the compounds of component C) comprising compounds of formula P according to the invention. The media preferably comprise one, two or three, more preferably one or two and most preferably one compound of the formula P according to the invention.

[0392] By means of suitable additives, the liquid-crystalline phases of the present invention can be modified in such a way that they can be used in all types of liquid-crystal display elements that have been disclosed hitherto. Additives of this type are known to the person skilled in the art and are described in detail in the literature (H. Kelker/R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980). For example, pleochroic dyes can be added for the production of coloured guest-host systems or substances can be added in order to modify the dielectric anisotropy, the viscosity and/or the alignment of the nematic phases.

[0393] The media according to the invention are prepared in a manner conventional per se. In general, the components are dissolved in one another, preferably at elevated temperature.

[0394] Accordingly the present invention relates further to methods for the production of an LC medium according to the present invention, comprising the step of mixing one or more compounds of formula I with a liquid-crystalline component B) comprising one or more mesogenic or liquid-crystalline compounds as described above.

[0395] The present invention further relates to a process for the fabrication of liquid crystal displays comprising at least the steps of: [0396] providing a first substrate which includes a pixel electrode and a common electrode for generating an electric field substantially parallel to a surface of the first substrate in the pixel region; [0397] providing a second substrate, the second substrate being disposed opposite to the first substrate; [0398] interposing a liquid crystal mixture between the first substrate and the second substrate, the liquid crystal mixture comprising one or more compounds of formula I, component B) and optionally component C); [0399] irradiating the liquid crystal mixture with linearly polarised light causing photoalignment of the liquid crystal; [0400] curing the polymerizable compounds of the liquid crystal mixture by irradiation with ultraviolet light or visible light having a wavelength of 450 nm or below.

[0401] The present invention further relates to the use of the liquid crystal mixtures according to the invention for the fabrication of a liquid crystal display.

[0402] The present invention further relates to liquid crystal displays fabricated by the process described above.

[0403] In the following, the production process according to the present invention is described in greater detail.

[0404] The first substrate includes a pixel electrode and a common electrode for generating an electric field substantially parallel to the surface of the first substrate in the pixel region. Various kinds of displays having at least two electrodes on one substrate are known to the skilled person wherein the most significant difference is that either both the pixel electrode and the common electrode are structured, as it is typical for IPS displays, or only the pixel electrode is structured and the common electrode is unstructured, which is the case for FFS displays.

[0405] It has to be understood that the present invention refers to any kind of electrode configurations suitable for generating an electric field substantially parallel to a surface of the first substrate in the pixel region; mentioned above, i.e. IPS as well as FFS displays.

[0406] The process according to the present invention is independent of the kind of substrate or material of the surface which is in contact with the liquid crystal mixture according to the invention, during and after this process. Examples of materials used for the substrates or surfaces are organic polymers including polyimide, indium tin oxide (ITO), indium zinc oxide (IZO), silicon nitride (SiN.sub.x) and silicon dioxide (SiO.sub.2). The process is especially suitable for the use in displays containing substrates that do not have a polyimide layer on one or more of the surfaces that are in contact with the liquid crystal.

[0407] In case one or more substrates contain a polyimide layer, the polyimide can be rubbed or not rubbed, preferably not rubbed.

[0408] Hence, the invention relates to a display produced by the process according to the invention in which the substrates contain a rubbed or unrubbed polyimide layer, preferably an unrubbed polyimide layer.

[0409] The invention further relates to a display produced by the process according to the invention in which none or only one of the top and bottom substrates contains a polyimide layer.

[0410] In one embodiment of the present invention the liquid crystal composition is injected between the first and second substrate r is filled into the cell by capillary force after combining the first and second substrate. In an alternative embodiment, the liquid crystal composition may be interposed between the first and second substrates by combining the second substrate to the first substrate after loading the liquid crystal composition on the first substrate. Preferably, the liquid crystal is dispensed dropwise onto a first substrate in a process known as “one drop filling” (ODF) process, as disclosed in for example JPS63-179323 and JPH10-239694, or using the Ink Jet Printing (IJP) method.

[0411] In a preferred embodiment, the process according to the invention contains a process step where the liquid crystal inside the display panel is allowed to rest for a period of time in order to evenly redistribute the liquid crystal medium inside the panel (herein referred to as “annealing”).

[0412] However it is likewise preferred that the annealing step is combined with a previous step, such as edge sealant pre-curing. In which case a ‘separate’ annealing step may not be necessary at all.

[0413] For the production of the displays according to the present invention, the photoreactive mesogen of formula I is preferably allowed to redistribute in the panel. After filling and assembly, the display panel is annealed for a time between 1 min and 3 h, preferably between 2 min and 1 h and most preferably between 5 min and 30 min. The annealing is preferably performed at room temperature.

[0414] In an alternative embodiment, the annealing is performed at elevated temperature, preferably at above 20° C. and below 140° C., more preferably above 40° C. and below 100° C. and most preferably above 50° C. and below 80° C.

[0415] In a preferred embodiment, one or more of the process steps of filling the display, annealing, photoalignment and curing of the polymerizable compound is performed at a temperature above the clearing point of the liquid crystal host mixture.

[0416] During the photoalignment of the liquid crystal inside the liquid crystal panel, anisotropy is induced by exposing the display or the liquid crystal layer to linearly polarised light.

[0417] In a preferred embodiment of the present invention the photoreactive component A) comprising one or more compounds of formula I, is photoaligned in a first step using linearly polarised light and in a second step further cured using linearly polarized or unpolarised UV light. In the second step the optional component C) is also further cured.

[0418] In another preferred embodiment, the linearly polarised light applied according to the inventive process is ultraviolet light which enables simultaneous photoalignment and photocuring of the photoreactive component A) comprising one or more compounds of formula I, and, if present, photocuring of the polymerizable component C).

[0419] Photoalignment of the photoreactive compounds of formula I and curing of the polymerizable groups of compounds of formula I and the curing of the optional polymerizable compounds of formula P can be performed simultaneously or stepwise. In case the process is split into different steps, the individual steps can be performed at the same temperature or at different temperatures.

[0420] After the photoalignment and curing step(s) a so-called “post-curing” step can optionally be performed by irradiation with UV-light and/or visible light (both either linearly or unpolarised) at reduced temperature in order to remove unreacted polymerizable compounds. The post-curing is preferably performed at above 0° C. and below the clearing point of the utilized LC mixture, preferably 20° C. and below 60° C.° C., and most preferably above 20° C. and below 40° C.

[0421] The polymerizable compounds are optionally polymerised or crosslinked (if a polymerizable compound contains two or more polymerizable groups) with the application of an electrical field. The polymerisation can be carried out in one or more steps.

[0422] Suitable and preferred polymerisation methods for component C) are, for example, thermal or photopolymerization, preferably photopolymerization, in particular UV photopolymerization. One or more initiators can optionally also be added here. Suitable conditions for the polymerisation and suitable types and amounts of initiators are known to the person skilled in the art and are described in the literature. Suitable for free-radical polymerisation are, for example, the commercially available photoinitiators Irgacure651®, Irgacure184®, Irgacure907®, Irgacure369® or Darocurel 173® (BASF SE). If an initiator is employed, its proportion is preferably 0.001 to 5% by weight, particularly preferably 0.001 to 1% by weight.

[0423] The present invention also relates to electro-optical liquid-crystal display elements containing a liquid-crystalline medium according to the invention, which is preferably homogeneously aligned. In a preferred embodiment the liquid crystal display is of the IPS or FFS mode.

[0424] Further combinations of the embodiments and variants of the invention in accordance with the description arise from the claims.

[0425] The invention is explained in greater detail below with reference to working examples, but without intending to be restricted thereby. The person skilled in the art will be able to glean from the examples working details that are not given in detail in the general description, generalise them in accordance with general expert knowledge and apply them to a specific problem.

[0426] Besides the usual and well-known abbreviations, the following abbreviations are used:

[0427] C: crystalline phase; N: nematic phase; Sm: smectic phase; I: isotropic phase. The numbers between these symbols show the transition temperatures of the substance concerned.

[0428] Temperature data are in ° C., unless indicated otherwise.

[0429] Physical, physicochemical or electro-optical parameters are determined by generally known methods, as described, inter alia, in the brochure “Merck Liquid Crystals—Licristal®—Physical Properties of Liquid Crystals—Description of the Measurement Methods”, 1998, Merck KGaA, Darmstadt.

[0430] Above and below, Δn denotes the optical anisotropy (589 nm, 20° C.) and Δε denotes the dielectric anisotropy (1 kHz, 20° C.). The dielectric anisotropy Δε is determined at 20° C. and 1 kHz. The optical anisotropy Δn is determined at 20° C. and a wavelength of 589.3 nm.

[0431] The Δε and Δn values and the rotational viscosity (γ.sub.1) of the compounds according to the invention are obtained by linear extrapolation from liquid-crystalline mixtures consisting of 5 to 10% of the respective compound according to the invention and 90-95% of the commercially available liquid-crystal mixture ZLI-2857 (for Δε) or ZLI-4792 (for Δn, γ.sub.1) (mixtures, Merck KGaA, Darmstadt).

[0432] The compounds used in the present invention are prepared by methods known per se, as described in the literature (for example in the standard works, such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), to be precise under reaction conditions which are known and suitable for the said reactions. Use can also be made here of variants known per se, which are not mentioned here in greater detail.

[0433] In the present invention and especially in the following examples, the structures of the mesogenic compounds are indicated by means of abbreviations, also called acronyms. In these acronyms, the chemical formulae are abbreviated as follows using Tables A to C below. All groups C.sub.nH.sub.2n+1, C.sub.mH.sub.2m+1 and C.sub.lH.sub.2l+1 or C.sub.nH.sub.2n−1, C.sub.mH.sub.2m−1 and C.sub.lH.sub.2l−1 denote straight-chain alkyl or alkenyl, preferably 1E-alkenyl, each having n, m and l C atoms respectively. Table A lists the codes used for the ring elements of the core structures of the compounds, while Table B shows the linking groups. Table C gives the meanings of the codes for the left-hand or right-hand end groups. The acronyms are composed of the codes for the ring elements with optional linking groups, followed by a first hyphen and the codes for the left-hand end group, and a second hyphen and the codes for the right-hand end group. Table D shows illustrative structures of compounds together with their respective abbreviations.

TABLE-US-00002 TABLE A Ring elements C [00177] embedded image P [00178] D [00179] DI [00180] A [00181] AI [00182] G [00183] GI [00184] U [00185] UI [00186] Y [00187] M [00188] MI [00189] N [00190] NI [00191] Np [00192] dH [00193] N3f [00194] N3fI [00195] tH [00196] tHI [00197] tH2f [00198] tH2fI [00199] K [00200] KI [00201] L [00202] LI [00203] F [00204] embedded image FI [00205] Nf [00206] NfI [00207]

TABLE-US-00003 TABLE B Linking groups E —CH.sub.2CH.sub.2— Z —CO—O— V —CH═CH— ZI —O—CO— X —CF═CH— O —CH.sub.2—O— XI —CH═CF— OI —O—CH.sub.2— B —CF═CF— Q —CF.sub.2—O— T —C≡C— QI —O—CF.sub.2— W —CF.sub.2CF.sub.2— T —C≡C—

TABLE-US-00004 TABLE C End groups Left-hand side Right-hand side Use alone -n- C.sub.nH.sub.2n+1— -n —C.sub.nH.sub.2n+1 -nO- C.sub.nH.sub.2n+1—O— -nO —O—C.sub.nH.sub.2n+1 -V- CH.sub.2═CH— -V —CH═CH.sub.2 -nV- CnH.sub.2n+1—CH═CH— -nV —C.sub.nH.sub.2n—CH═CH.sub.2 -Vn- CH.sub.2═CH— C.sub.nH.sub.2n+1— -Vn —CH═CH—C.sub.nH.sub.2n+1 -nVm- C.sub.nH.sub.2n+1—CH═CH—C.sub.mH.sub.2m— -nVm —C.sub.nH.sub.2n—CH═CH—C.sub.mH.sub.2m+1 -N- N≡C— -N —C═N -S- S═C═N— -S —N═C═S -F- F— -F —F -CL- Cl— -CL —Cl -M- CFH.sub.2— -M —CFH.sub.2 -D- CF.sub.2H— -D —CF.sub.2H -T- CF.sub.3— -T —CF.sub.3 -MO- CFH.sub.2O— -OM —OCFH.sub.2 -DO- CF.sub.2HO— -OD —OCF.sub.2H -TO- CF.sub.3O— -OT —OCF.sub.3 -FXO- CF.sub.2═CH—O— -OXF —O—CH═CF.sub.2 -A- H—C≡C— -A —C≡C—H -nA- C.sub.nH.sub.2n+1—C≡C— -An —C≡C—C.sub.nH.sub.2n+1 -NA- N≡O—O≡O— -AN —C≡C—C≡N

TABLE-US-00005 -. . . A . . .- —C≡— -. . . A . . . —C═— -. . . V . . .- CH═CH— -. . . V . . . —CH═CH— -. . . Z . . .- —CO—O— -. . . Z . . . —CO—O— -. . . ZI . . .- —O—CO— -. . . ZI . . . —O—CO— -. . . K . . .- —CO— -. . . K . . . —CO— -. . . W . . .- —CF═CF— -. . . W . . . —CF═CF—
wherein n and m each denote integers, and the three dots “ . . . ” are placeholders for other abbreviations from this table.

[0434] The following table shows illustrative structures together with their respective abbreviations. These are shown in order to illustrate the meaning of the rules for the abbreviations. They furthermore represent compounds which are preferably used.

TABLE-US-00006 TABLE D Illustrative structures [00208] embedded image [00209] [00210] [00211] [00212] [00213] [00214] [00215] [00216] [00217] [00218] [00219] [00220] [00221] [00222] [00223] [00224] [00225] [00226] [00227] [00228] [00229] [00230] [00231] [00232] [00233] [00234] [00235] [00236] [00237] [00238] [00239] [00240] [00241] [00242] [00243] [00244] embedded image [00245] [00246] [00247] [00248] [00249] [00250] [00251] [00252] [00253] [00254] [00255] [00256] [00257] [00258] [00259] [00260] [00261] [00262] [00263] [00264] [00265] [00266] [00267] [00268] [00269] [00270] [00271] [00272] [00273] [00274] [00275] [00276] [00277] [00278] [00279] [00280] embedded image [00281] [00282] [00283] [00284] [00285] [00286] [00287] [00288] [00289] [00290] [00291] [00292] [00293] [00294] [00295] [00296] [00297] [00298] [00299] [00300] [00301] [00302] [00303] [00304] [00305] [00306] [00307] [00308] [00309] [00310] [00311] [00312] [00313] [00314] [00315] [00316] embedded image [00317] [00318] [00319] [00320] [00321] [00322] [00323] [00324] [00325] [00326] [00327] [00328] [00329] [00330] [00331] [00332] [00333] [00334] [00335] [00336] [00337] [00338] [00339] [00340] [00341] [00342] [00343] [00344] [00345] [00346] [00347] [00348] [00349] [00350] [00351] [00352] embedded image [00353] [00354] [00355] [00356] [00357] [00358] [00359] [00360] [00361] [00362] [00363] [00364] [00365] [00366] [00367] [00368] [00369] [00370] [00371] [00372] [00373]
wherein n, m and l preferably, independently of one another, denote 1 to 7.

[0435] The following table, Table E, shows illustrative compounds which can be used as additional stabilisers in the mesogenic media according to the present invention.

TABLE-US-00007 TABLE E Table E shows possible stabilisers which can be added to the LC media according to the invention. (n here denotes an integer from 1 to 12, preferably 1,2, 3, 4, 5, 6, 7 or 8, terminal methyl groups are not shown). [00374] embedded image [00375] [00376] [00377] [00378] [00379] [00380] [00381] [00382] [00383] [00384] [00385] [00386] [00387] [00388] [00389] [00390] [00391] [00392] [00393] [00394] [00395] [00396] [00397] [00398] [00399] [00400] [00401] [00402] [00403] [00404] [00405] [00406] [00407] [00408] [00409] [00410] embedded image [00411] [00412] [00413] [00414] [00415] [00416] [00417] [00418] [00419]

[0436] The LC media preferably comprise 0 to 10% by weight, in particular 1 ppm to 5% by weight, particularly preferably 1 ppm to 1% by weight, of stabilisers.

[0437] Table F below shows illustrative compounds which can preferably be used as chiral dopants in the mesogenic media according to the present invention.

TABLE-US-00008 TABLE F [00420] embedded image [00421] [00422] [00423] [00424] [00425] [00426] [00427] [00428] [00429] [00430] [00431] [00432] [00433]

[0438] In a preferred embodiment of the present invention, the mesogenic media comprise one or more compounds selected from the group of the compounds from Table F.

[0439] The mesogenic media according to the present application preferably comprise two or more, preferably four or more, compounds selected from the group consisting of the compounds from the above tables.

[0440] The liquid-crystal media according to the present invention preferably comprise [0441] seven or more, preferably eight or more, individual compounds, preferably of three or more, particularly preferably of four or more, different formulae, selected from the group of the compounds from Table D.

[0442] Hereinafter, the present invention is described in more detail and specifically with reference to the Examples, which however are not intended to limit the present invention.

EXAMPLES

[0443] Utilized Photoreactive Compounds of Formula I:

##STR00434##

[0444] Utilized Polymerizable Compounds for Comparison

##STR00435##

[0445] Utilized Polymerizable Compounds of Formula P:

##STR00436##

[0446] Nematic Host Mixture

[0447] The nematic LC host mixture N-1 is prepared as indicated in the following table:

[0448] Mixture N-1:

TABLE-US-00009 Composition [%- w/w] Physical properties CC-3-V 36.00 CC-3-V1 5.00 cl.p. [° C.]: 78 CCP-V-1 8.00 n.sub.e [589 nm, 20° C.]: 1.5907 PGP-2-2V 3.00 Δn [589 nm, 20° C.]: 0.1095 CCQU-3-F 9.5 ε.sub.|| [1 kHz, 20° C.]: 16.6 PUQU-3-F 8.5 ε.sub.⊥ [1 kHz, 20° C.]: 3.7 APUQU-2-F 5.00 Δε [1 kHz, 20° C.]: 12.9 APUQU-3-F 8.00 K.sub.1 [pN, 20° C.]: 12.1 PGUQU-3-F 4.00 K.sub.3 [pN, 20° C.]: 13.4 PGUQU-4-F 8.00 K.sub.3/K.sub.1 [pN, 20° C.]: 1.11 PGUQU-5-F 5.00 V.sub.0 [V, 20° C.]: 1.01 Σ 100.0 LTS bulk [h, −20° C.]: 1000

[0449] Conditions

[0450] All the examples detailed in this working examples are subject to standard conditions for SA-IPS/FFS materials. In detail, an exposure power of 35 mWcm.sup.−2 after a wire grid polarizer is used with a UV source of an Omnicure S2000 mercury lamp. The photoreactive compound I-1 requires exposure with a 320 nm cutoff filter, all other additives require a 360 nm cutoff filter. The exposure time is typically in the range of 30 seconds to 180 seconds, as stated in the data tables. All samples are exposed with the same cell held at 100° C. Cells used are 6 um PI-free 1 cm×1 cm ITO electrode area, glass type is Eagle XG AF glass by Corning (0.7 mm thick).

MIXTURE EXAMPLES

[0451] Grey-Value Experiment

[0452] The following LC mixtures are prepared from the nematic host mixture N-1 listed above and the given amount of Photoreactive compound (1) and polymerisable compounds (p) was mixed, according to the compositions given in the following table.

TABLE-US-00010 Photo- Photo- reactive Poly- Poly- reactive compound merizable merizable Comparative compound concentration compound compound Examples (I) (%) (P) (%) CM 1 I-1 0.5 / / CM 2 I-1 0.5 RM-1 0.7 CM 3 I-2 0.5 / /

TABLE-US-00011 Photo- Photo- reactive Poly- Poly- reactive compound merizable merizable Mixture compound concentration compound compound Examples (I) (%) (P) (%) M 1 I-2 0.5 P-1 0.5 M 2 I-2 0.5 P-1 0.7

[0453] After processing, microscope pictures with a ×10 objective are taken of all cells between crossed polarisers under identical conditions and the sample is rotated to give the best dark state. Then the average grey-value of each picture is a measure of the dark state quality. The following table summarises the results of the measurements.

TABLE-US-00012 Mixture composition Grey-Value CM 1 20.9 +/− 1.1 CM 2 30.6 +/− 4.2 CM 3 21.4 +/− 2.2 M 1 20.4 +/− 1.2 M 2 23.4

[0454] From the table, it can be seen that the typical grey-value of a mixture without co-monomers is around 21. When using 0.7% of polymerizable mesogenic compound RM-1 as co-monomer the grey-value is significantly increased by 50%. In contrast when using 0.5% of P-1 as co-monomer, the dark state is beneficially comparable to that of the pure additive. When adding 0.7% P-1 the grey-value is only slightly increased.

[0455] Film Thickness

[0456] AFM thickness measurements were carried out for selected samples to document the expected layer increase. In case of addition of 0.5% P-1 to a mixture with 0.5% I-1 an increase of the average film thickness from 6 nm to 10 nm is observed. The experiment further shows clearly that there is an advantage of using compounds of formula P that do not absorb light at 365 nm. The increased layer thickness measured by AFM is expected to increase reliability parameters that are linked to permeability or mechanical stress.

[0457] Dark State Experiment

[0458] The following LC mixtures are prepared from the nematic host mixture N-1 listed above and the given amount of Photoreactive compound (I) and polymerisable compounds (p) was mixed, according to the compositions given in the following tables.

TABLE-US-00013 Photo- Photo- reactive Poly- Poly- reactive compound merizable merizable Comparative compound concentration compound compound Examples (I) (%) (P) (%) CM 4 I-2 0.5 / / CM 5 I-2 0.7 / / CM 6 I-2 0.7 RM-1 0.5 CM 7 I-2 0.7 RM-2 0.5 CM 8 I-2 0.7 RM-1 0.7 CM 9 I-2 0.7 RM-2 0.7

TABLE-US-00014 Photo- Photo- reactive Poly- Poly- reactive compound merizable merizable Mixture compound concentration compound compound Examples (I) (%) (P) (%) M 3 I-2 0.5 P-1 0.5 M 4 I-2 0.5 P-1 0.7 M 5 I-2 0.7 P-1 0.5 M 6 I-2 0.7 P-1 0.7 M 7 I-2 0.7 P-2 0.7 M 8 I-2 0.7 P-2 1.0 M 9 I-2 0.7 P-3 0.7 M 10 I-2 0.7 P-3 1.0 M 11 I-2 0.7 P-3 0.7 M 12 I-2 0.7 P-3 1.0

[0459] The mixture were investigated with respect to their dark state under different UV conditions. The number given for the dark state in the following table is the ratio of the dark state over the bright state corrected by the dark state of the empty cell.

TABLE-US-00015 Comparative Mixture Darkstate UV1 time CM 4 0.12 3 min CM 5 0.12 3 min CM 6 0.27 2 min CM 7 0.24 1 min CM 8 0.20 1 min CM 9 0.24 1 min M 3 0.14 2 min M 4 0.17 1 min M 5 0.19 1 min M 6 0.22 1 min M 7 0.19 2 min M 8 0.19 2 min M 9 0.18 1 min M 10 0.18 2 min M 11 0.17 2 min M 12 0.29 1 min

[0460] From the above given table can be seen that mixtures with RM-1 and RM-2 typically show significant decreased dark states above 0.2 in comparison to mixtures without co-monomers. In contrast to that the dark states of mixtures comprising one or more compounds of formula P are mostly below 0.2 and therefore comparable to mixtures without comonomers.

LIQUID CRYSTAL MIXTURE AND LIQUID CRYSTAL DISPLAY

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Abstract

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Description