Polymerisable compounds and the use thereof in liquid-crystal displays

Abstract

The present invention relates to polymerisable compounds, to processes and intermediates for the preparation thereof, to liquid-crystal (LC) media comprising them, and to the use of the polymerisable compounds and LC media for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of the polymer sustained alignment type.

Claims

1. A compound of formula I
P-Sp-A.sup.1-(Z.sup.1-A.sup.2).sub.z-R  I wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings P is a polymerisable group, Sp is a spacer group or a single bond, A.sup.1-(Z-A.sup.2).sub.z- is selected from the following formulae ##STR00625## wherein at least one benzene ring is substituted by exactly one group L.sup.11 and the benzene rings are optionally further substituted by one or more groups L or P-Sp- L.sup.11 is —CH.sub.2—O—CH.sub.3, R is P-Sp-, L is F, Cl, —CN, P-Sp- or straight chain alkyl having 1 to 25 C atoms, branched alkyl having 3 to 25 C atoms, or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups of the straight, branched or cyclic alkyl groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by P-Sp-, F or Cl, z is 0, 1, 2 or 3, with the proviso that at least one group Sp is a single bond.

2. A compound selected from the following formulae: ##STR00626## wherein R is H, L is F, Cl, —CN, P-Sp- or straight chain alkyl having 1 to 25 C atoms, branched alkyl having 3 to 25 C atoms, or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH2-groups of the straight, branched or cyclic alkyl groups are optionally replaced by —O—, —S—, —CO—, —OO—O—, —O—CO—, —O—CO—O— in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by P-Sp-, F or Cl, r1, r3, r6 are independently of each other 0, 1, 2 or 3, r1, r3, r6 are independently of each other 0, 1, 2 or 3, r2 is 0, 1, 2, 3 or 4, r4 and r5 are independently of each other 0, 1 or 2, wherein r1+r6≥1, r1+r2+r3≥1, r4+r5≥1, r1+r3+r4≥1 and at least one group L denotes —CH.sub.2—O—CH.sub.3, and wherein at least one benzene ring is substituted by exactly one-CH.sub.2—O—CH.sub.3 group and wherein at least one of the groups Sp is a single bond.

3. The compound according to claim 1, which is selected from the following subformulae: ##STR00627## ##STR00628## ##STR00629## wherein P, Sp, P(Sp).sub.2, L, have the meanings given in claim 1 and r1, r3, r6 are independently of each other 0, 1, 2 or 3, r2 is 0, 1, 2, 3 or 4, r4, r5, r6 are independently of each other 0, 1 or 2, wherein r1+r6≥1, r1+r2+r3≥1, r4+r5≥1, r1+r3+r4≥1, and at least one group L denotes —CH.sub.2—O—CH.sub.3, and wherein at least one of the groups Sp is a single bond.

4. The compound according to claim 1, wherein P denotes acrylate or methacrylate.

5. The compound according to claim 1, wherein Sp is a single bond or denotes —(CH.sub.2).sub.p2—, —(CH.sub.2).sub.p2—O—, —(CH.sub.2).sub.p2—CO—O—, —(CH.sub.2).sub.p2—O—CO—, wherein p2 is 2, 3, 4, 5 or 6, and the O-atom or the CO-group, respectively, is connected to the benzene ring.

6. A liquid crystal (LC) medium comprising one or more polymerisable compounds of formula I as defined in claim 1.

7. The LC medium, characterized in that it comprises a polymerisable component A) comprising one or more polymerisable compounds of formula I as defined in claim 1, and a liquid-crystalline LC component B) comprising one or more mesogenic or liquid-crystalline compounds.

8. The LC medium of claim 6, characterized in that it additionally comprises one or more compounds of the formulae CY and/or PY: ##STR00630## in which the individual radicals have the following meanings: a denotes 1 or 2, b denotes 0 or 1, ##STR00631## denotes ##STR00632## 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.

9. The LC medium according to claim 6, characterized in that it additionally comprises one or more compounds selected from the following formulae: ##STR00633## in which the individual radicals, on each occurrence identically or differently, each, independently of one another, have the following meaning: ##STR00634## R.sup.A1 is alkenyl having 2 to 9 C atoms or, if at least one of the rings X, Y and Z denotes cyclohexenyl, also one of the meanings of R.sup.A2, R.sup.A2 is 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—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, Z.sup.x is —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, L.sup.1-4 each, independently of one another, is H, F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F or CHF.sub.2H, x is 1 or 2, z is 0 or 1.

10. The LC medium according to claim 6, characterized in that it additionally comprises one or more compounds of the following formula: ##STR00635## in which the individual radicals have the following meanings: ##STR00636## denotes ##STR00637## denotes ##STR00638## 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—, —COO—, —OCO—, —C.sub.2F.sub.4—, —CF═CF— or a single bond.

11. The LC medium according to claim 6, characterized in that the polymerisable compounds of formula I are polymerised.

12. A process of preparing an LC medium of claim 7, comprising the steps of mixing one or more mesogenic or liquid-crystalline compounds with one or more compounds of formula I, and optionally with further liquid-crystalline compounds and/or additives.

13. An LC display comprising one or more compounds of formula I as defined in claim 1.

14. The LC display of claim 13, which is a PSA display.

15. The LC display of claim 14, which is a PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS, PS-posi-VA, PS-TN, polymer stabilised SA-VA or polymer stabilised SA-FFS display.

16. A LC display comprising two substrates, at least one which is transparent to light, an electrode provided on each substrate or two electrodes provided on only one of the substrates, and located between the substrates a layer of an LC medium, comprising one or more polymerisable compounds, as defined in claim 6, wherein the polymerisable compounds are polymerised between the substrates of the display.

17. A process for the production of an LC display comprising the steps of providing an LC medium comprising one or more polymerisable compounds, as defined in claim 6, between the substrates of the display, and polymerising the polymerisable compounds.

18. A compound of formula II
Pg-Sp-A.sup.1-(Z.sup.1-A.sup.2).sub.z-R*  II wherein Pg denotes OH, a protected hydroxyl group or a masked hydroxyl group, R* denotes R or Pg-Sp-, and Sp, A.sup.1-(Z-A.sup.2).sub.z- and R have the meanings given in claim 1.

19. A process for preparing a compound of formula I according to claim 1, by esterification of a compound of formula II,
Pg-Sp-A.sup.1-(Z.sup.1-A.sup.2).sub.z-R*  II, wherein Pg denotes OH, R* denotes R or Pg-Sp- and Sp, A.sup.1-(Z-A.sup.2).sub.z- and R have the meanings given in claim 1, using corresponding acids, acid derivatives, or halogenated compounds containing a group P, as defined in claim 1, in the presence of a dehydrating reagent.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The compounds of formula I show the following advantageous properties when used in PSA displays: a suitable tilt generation which is inside a certain process window, fast polymerization leading to minimal residues of RM after the UV-process, a high voltage-holding-ratio after the UV-process, good tilt stability, sufficient stability against heat, sufficient solubility in organic solvents typically used in display manufacture.

(2) In particular the compounds of formula I combine a fast polymerisation speed which is similar to terphenyl RMs with good reliability parameters similar to biphenyl RMs. This results in a superior overall performance of the compounds compared to RMs of the state of the art when used in PSA displays.

(3) In the compounds of formula I the presence of one or more methoxymethylene substituents L.sup.11 on the benzene or naphthylene rings were found to enhance superior properties of the compounds, like fast polymerisation speed and good reliability. However, the substituents L.sup.11 are not designated as a polymerisable or crosslinkable group that should participate in the polymerisation reaction of the compound.

(4) A preferred embodiment of the present invention thus relates to the use of the compounds of formula I in a polymerisation reaction where the conditions for polymerisation of the groups P are selected such that the methoxymethylene substituents, or groups L.sup.11, do not participate in the polymerisation reaction.

(5) Unless stated otherwise, the compounds of formula I are preferably selected from achiral compounds.

(6) As used herein, the terms “active layer” and “switchable layer” mean a layer in an electrooptical display, for example an LC display, that comprises one or more molecules having structural and optical anisotropy, like for example LC molecules, which change their orientation upon an external stimulus like an electric or magnetic field, resulting in a change of the transmission of the layer for polarized or unpolarized light.

(7) As used herein, the terms “tilt” and “tilt angle” will be understood to mean a tilted alignment of the LC molecules of an LC medium relative to the surfaces of the cell in an LC display (here preferably a PSA display). The tilt angle here denotes the average angle (<90°) between the longitudinal molecular axes of the LC molecules (LC director) and the surface of the plane-parallel outer plates which form the LC cell. A low value for the tilt angle (i.e. a large deviation from the 90° angle) corresponds to a large tilt here. A suitable method for measurement of the tilt angle is given in the examples. Unless indicated otherwise, tilt angle values disclosed above and below relate to this measurement method.

(8) As used herein, the terms “reactive mesogen” and “RM” will be understood to mean a compound containing a mesogenic or liquid crystalline skeleton, and one or more functional groups attached thereto which are suitable for polymerisation and are also referred to as “polymerisable group” or “P”.

(9) Unless stated otherwise, the term “polymerisable compound” as used herein will be understood to mean a polymerisable monomeric compound.

(10) An SA-VA or SA-FFS according to the present invention will be of the polymer stabilised mode as it contains, or is manufactured by use of, an LC medium containing an RM of formula I. Consequently as used herein, the terms “SA-VA display” and “SA-FFS display”, when referring to a display according to the present invention, will be understood to refer to a polymer stabilised SA-VA or SA-FFS display even if not explicitly mentioned.

(11) As used herein, the term “low-molecular-weight compound” will be understood to mean to a compound that is monomeric and/or is not prepared by a polymerisation reaction, as opposed to a “polymeric compound” or a “polymer”.

(12) As used herein, the term “unpolymerisable compound” will be understood to mean a compound that does not contain a functional group that is suitable for polymerisation under the conditions usually applied for the polymerisation of the RMs.

(13) The term “mesogenic group” as used herein is known to the person skilled in the art and described in the literature, and means a group which, due to the anisotropy of its attracting and repelling interactions, essentially contributes to causing a liquid-crystal (LC) phase in low-molecular-weight or polymeric substances. Compounds containing mesogenic groups (mesogenic compounds) do not necessarily have to have an LC phase themselves. It is also possible for mesogenic compounds to exhibit LC phase behaviour only after mixing with other compounds and/or after polymerisation. Typical mesogenic groups are, for example, rigid rod- or disc-shaped units. An overview of the terms and definitions used in connection with mesogenic or LC compounds is given in Pure Appl. Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368.

(14) The term “spacer group”, hereinafter also referred to as “Sp”, as used herein is known to the person skilled in the art and is described in the literature, see, for example, Pure Appl. Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368. As used herein, the terms “spacer group” or “spacer” mean a flexible group, for example an alkylene group, which connects the mesogenic group and the polymerisable group(s) in a polymerisable mesogenic compound.

(15) Above and below,

(16) ##STR00002##
denotes a trans-1,4-cyclohexylene ring, and

(17) ##STR00003##
denotes a 1,4-phenylene ring.

(18) In a group

(19) ##STR00004##
the single bond shown between the two ring atoms can be attached to any free position of the benzene ring.

(20) Above and below “organic group” denotes a carbon or hydrocarbon group.

(21) “Carbon group” denotes a mono- or polyvalent organic group containing at least one carbon atom, where this either contains no further atoms (such as, for example, —C≡C—) or optionally contains one or more further atoms, such as, for example, N, O, S, B, P, Si, Se, As, Te or Ge (for example carbonyl, etc.). The term “hydrocarbon group” denotes a carbon group which additionally contains one or more H atoms and optionally one or more heteroatoms, such as, for example, N, O, S, B, P, Si, Se, As, Te or Ge.

(22) “Halogen” denotes F, Cl, Br or I, preferably F or Cl.

(23) —CO—, —C(═O)— and —C(O)— denote a carbonyl group, i.e.

(24) ##STR00005##

(25) A carbon or hydrocarbon group can be a saturated or unsaturated group. Unsaturated groups are, for example, aryl, alkenyl or alkynyl groups. A carbon or hydrocarbon radical having more than 3 C atoms can be straight-chain, branched and/or cyclic and may also contain spiro links or condensed rings.

(26) The terms “alkyl”, “aryl”, “heteroaryl”, etc., also encompass polyvalent groups, for example alkylene, arylene, heteroarylene, etc.

(27) The term “aryl” denotes an aromatic carbon group or a group derived therefrom. The term “heteroaryl” denotes “aryl” as defined above, containing one or more heteroatoms, preferably selected from N, O, S, Se, Te, Si and Ge.

(28) Preferred carbon and hydrocarbon groups are optionally substituted, straight-chain, branched or cyclic, alkyl, alkenyl, alkynyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy having 1 to 40, preferably 1 to 20, very preferably 1 to 12, C atoms, optionally substituted aryl or aryloxy having 5 to 30, preferably 6 to 25, C atoms, or optionally substituted alkylaryl, arylalkyl, alkylaryloxy, arylalkyloxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy and aryloxycarbonyloxy having 5 to 30, preferably 6 to 25, C atoms, wherein one or more C atoms may also be replaced by hetero atoms, preferably selected from N, O, S, Se, Te, Si and Ge.

(29) Further preferred carbon and hydrocarbon groups are C.sub.1-C.sub.20 alkyl, C.sub.2-C.sub.20 alkenyl, C.sub.2-C.sub.20 alkynyl, C.sub.3-C.sub.20 allyl, C.sub.4-C.sub.20 alkylidenyl, C.sub.4-C.sub.20 polyenyl, C.sub.6-C.sub.20 cycloalkyl, C.sub.4-C.sub.15 cycloalkenyl, C.sub.6-C.sub.30 aryl, C.sub.6-C.sub.30 alkylaryl, C.sub.6-C.sub.30 arylalkyl, C.sub.6-C.sub.30 alkylaryloxy, C.sub.6-C.sub.30 arylalkyloxy, C.sub.2-C.sub.30 heteroaryl, C.sub.2-C.sub.30 heteroaryloxy.

(30) Particular preference is given to C.sub.1-C.sub.12 alkyl, C.sub.2-C.sub.12 alkenyl, C.sub.2-C.sub.12 alkynyl, C.sub.6-C.sub.25 aryl and C.sub.2-C.sub.25 heteroaryl.

(31) Further preferred carbon and hydrocarbon groups are straight-chain, branched or cyclic alkyl having 1 to 20, preferably 1 to 12, C atoms, which are unsubstituted or mono- or polysubstituted by F, Cl, Br, I or CN and in which one or more non-adjacent CH.sub.2 groups may each be replaced, independently of one another, by —C(R.sup.x)═C(R.sup.x)—, —C≡C—, —N(R.sup.x)—, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that O and/or S atoms are not linked directly to one another.

(32) R.sup.x preferably denotes H, F, Cl, CN, a straight-chain, branched or cyclic alkyl chain having 1 to 25 C atoms, in which, in addition, one or more non-adjacent C atoms may be replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— and in which one or more H atoms may be replaced by F or Cl, or denotes an optionally substituted aryl or aryloxy group with 6 to 30 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group with 2 to 30 C atoms.

(33) Preferred alkyl groups are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, cyclopentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, dodecanyl, trifluoromethyl, perfluoro-n-butyl, 2,2,2-trifluoroethyl, perfluorooctyl, perfluorohexyl, etc.

(34) Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl, etc.

(35) Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, octynyl, etc.

(36) Preferred alkoxy groups are, for example, methoxy, ethoxy, 2-methoxyethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, 2-methylbutoxy, n-pentoxy, n-hexoxy, n-heptoxy, n-octoxy, n-nonoxy, n-decoxy, n-undecoxy, n-dodecoxy, etc.

(37) Preferred amino groups are, for example, dimethylamino, methylamino, methylphenylamino, phenylamino, etc.

(38) Aryl and heteroaryl groups can be monocyclic or polycyclic, i.e. they can contain one ring (such as, for example, phenyl) or two or more rings, which may also be fused (such as, for example, naphthyl) or covalently bonded (such as, for example, biphenyl), or contain a combination of fused and linked rings. Heteroaryl groups contain one or more heteroatoms, preferably selected from O, N, S and Se.

(39) Particular preference is given to mono-, bi- or tricyclic aryl groups having 6 to 25 C atoms and mono-, bi- or tricyclic heteroaryl groups having 5 to 25 ring atoms, which optionally contain fused rings and are optionally substituted. Preference is furthermore given to 5-, 6- or 7-membered aryl and heteroaryl groups, in which, in addition, one or more CH groups may be replaced by N, S or O in such a way that O atoms and/or S atoms are not linked directly to one another.

(40) Preferred aryl groups are, for example, phenyl, biphenyl, terphenyl, [1,1′:3′,1″]terphenyl-2′-yl, naphthyl, anthracene, binaphthyl, phenanthrene, 9,10-dihydro-phenanthrene, pyrene, dihydropyrene, chrysene, perylene, tetracene, pentacene, benzopyrene, fluorene, indene, indenofluorene, spirobifluorene, etc.

(41) Preferred heteroaryl groups are, for example, 5-membered rings, such as pyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole, furan, thiophene, selenophene, oxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 6-membered rings, such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine, or condensed groups, such as indole, isoindole, indolizine, indazole, benzimidazole, benzotriazole, purine, naphthimidazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole, quinoxalinimidazole, benzoxazole, naphthoxazole, anthroxazole, phenanthroxazole, isoxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, benzoisoquinoline, acridine, phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline, phenanthridine, phenanthroline, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene, dibenzothiophene, benzothiophene, benzothiadiazothiophene, or combinations of these groups.

(42) The aryl and heteroaryl groups mentioned above and below may also be substituted by alkyl, alkoxy, thioalkyl, fluorine, fluoroalkyl or further aryl or heteroaryl groups.

(43) The (non-aromatic) alicyclic and heterocyclic groups encompass both saturated rings, i.e. those containing exclusively single bonds, and also partially unsaturated rings, i.e. those which may also contain multiple bonds. Heterocyclic rings contain one or more heteroatoms, preferably selected from Si, O, N, S and Se.

(44) The (non-aromatic) alicyclic and heterocyclic groups can be monocyclic, i.e. contain only one ring (such as, for example, cyclohexane), or polycyclic, i.e. contain a plurality of rings (such as, for example, decahydronaphthalene or bicyclooctane). Particular preference is given to saturated groups. Preference is furthermore given to mono-, bi- or tricyclic groups having 5 to 25 ring atoms, which optionally contain fused rings and are optionally substituted. Preference is furthermore given to 5-, 6-, 7- or 8-membered carbocyclic groups, in which, in addition, one or more C atoms may be replaced by Si and/or one or more CH groups may be replaced by N and/or one or more non-adjacent CH.sub.2 groups may be replaced by —O— and/or —S—.

(45) Preferred alicyclic and heterocyclic groups are, for example, 5-membered groups, such as cyclopentane, tetrahydrofuran, tetrahydrothiofuran, pyrrolidine, 6-membered groups, such as cyclohexane, silinane, cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dioxane, 1,3-dithiane, piperidine, 7-membered groups, such as cycloheptane, and fused groups, such as tetrahydronaphthalene, decahydronaphthalene, indane, bicyclo[1.1.1]-pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, octahydro-4,7-methanoindane-2,5-diyl.

(46) Preferred substituents are, for example, solubility-promoting groups, such as alkyl or alkoxy, electron-withdrawing groups, such as fluorine, nitro or nitrile, or substituents for increasing the glass transition temperature (Tg) in the polymer, in particular bulky groups, such as, for example, t-butyl or optionally substituted aryl groups.

(47) Preferred substituents, hereinafter also referred to as “L.sup.S”, are, for example, F, Cl, Br, I, —CN, —NO.sub.2, —NCO, —NCS, —OCN, —SCN, —C(═O)N(R.sup.x).sub.2, —C(═O)Y.sup.1, —C(═O)R.sup.x, —N(R.sup.x).sub.2, straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy each having 1 to 25 C atoms, in which one or more H atoms may optionally be replaced by F or Cl, optionally substituted silyl having 1 to 20 Si atoms, or optionally substituted aryl having 6 to 25, preferably 6 to 15, C atoms,

(48) wherein R.sup.x denotes H, F, Cl, CN, or straight chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F, Cl, P— or P-Sp-, and
Y.sup.1 denotes halogen.

(49) “Substituted silyl or aryl” preferably means substituted by halogen, —CN, R.sup.0, —OR.sup.0, —CO—R.sup.0, —CO—O—R.sup.0, —O—CO—R.sup.0 or —O—CO—O—R.sup.0, wherein R.sup.0 denotes H or alkyl with 1 to 20 C atoms.

(50) Particularly preferred substituents L.sup.S are, for example, F, Cl, CN, NO.sub.2, CH.sub.3, C.sub.2H.sub.5, OCH.sub.3, OC.sub.2H.sub.5, COCH.sub.3, COC.sub.2H.sub.5, COOCH.sub.3, COOC.sub.2H.sub.5, CF.sub.3, OCF.sub.3, OCHF.sub.2, OC.sub.2F.sub.5, furthermore phenyl.

(51) ##STR00006##
is preferably

(52) ##STR00007##
in which L has one of the meanings indicated above.

(53) The polymerisable group P is a group which is 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.

(54) 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—,

(55) ##STR00008##
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—, in which 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 which are other than P-Sp-, 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.

(56) Very 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—,

(57) ##STR00009##
CH.sub.2═CW.sup.2—O—, CH.sub.2═CW.sup.2—, CW.sup.1═CH—CO—(O).sub.k3—, CW.sup.1═CH—CO—NH—, CH.sub.2═CW.sup.1—CO—NH—, (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—, 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— and W.sup.4W.sup.5W.sup.6Si—, in which 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 CI, 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, 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.

(58) Very 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—,

(59) ##STR00010##

(60) Further preferred polymerisable groups P are selected from the group consisting of vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, most preferably from acrylate and methacrylate.

(61) If the spacer group Sp is different from a single bond, it is preferably of the formula Sp″—X″, so that the respective radical P-Sp- conforms to the formula P-Sp″—X″-, wherein Sp″ denotes linear or branched 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 in which, 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.0R.sup.00—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —S—CO—, —CO—S—, —N(R.sup.00)—CO—O—, —O—CO—N(R.sup.0)—, —N(R.sup.0)—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, X″ denotes —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—OC—O—, —CO—N(R.sup.0)—, —N(R.sup.0)—CO—, —N(R.sup.0)—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.2═CY.sup.3—, —C≡C—, —CH═CH—CO—O—, —O—OC—CH═CH— or a single bond, R.sup.0 and R.sup.00 each, independently of one another, denote H or alkyl having 1 to 20 C atoms, and Y.sup.2 and Y.sup.3 each, independently of one another, denote H, F, Cl or CN.

(62) X″ is preferably —O—, —S—, —CO—, —COO—, —OCO—, —O—COO—, —CO—NR.sup.0—, —NR.sup.0—CO—, —NR.sup.0—CO—NR.sup.00— or a single bond.

(63) Typical spacer groups Sp and -Sp″—X″— are, for example, —(CH.sub.2).sub.p1—, —(CH.sub.2).sub.p1—O—, —(CH.sub.2).sub.p1—O—CO—, —(CH.sub.2).sub.p1—CO—O—, —(CH.sub.2).sub.p1—O—OC—O—, —(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.0R.sup.00—O).sub.p1—, in which p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R.sup.0 and R.sup.00 have the meanings indicated above.

(64) Particularly preferred groups Sp and -Sp″—X″— are —(CH.sub.2).sub.p1—, —(CH.sub.2).sub.p1—O—, —(CH.sub.2).sub.p1—O—CO—, —(CH.sub.2).sub.p1—CO—O—, —(CH.sub.2).sub.p1—O—OC—O—, in which p1 and q1 have the meanings indicated above.

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

(66) In a preferred embodiment of the invention the compounds of formula I and its subformulae contain a spacer group Sp that is substituted by one or more polymerisable groups P, so that the group Sp-P corresponds to Sp(P).sub.s, with s being (branched polymerisable groups).

(67) Preferred compounds of formula I according to this preferred embodiment are those wherein s is 2, i.e. compounds which contain a group Sp(P).sub.2. Very preferred compounds of formula I according to this preferred embodiment contain a group selected from the following formulae:
—X-alkyl-CHPP  S1
—X-alkyl-CH((CH.sub.2).sub.aaP)((CH.sub.2).sub.bbP)  S2
—X—N((CH.sub.2).sub.aaP)((CH.sub.2).sub.bbP)  S3
—X-alkyl-CHP—CH.sub.2—CH.sub.2P  S4
—X-alkyl-C(CH.sub.2P)(CH.sub.2P)—C.sub.aaH.sub.2aa+1  S5
—X-alkyl-CHP—CH.sub.2P  S6
—X-alkyl-CPP-C.sub.aaH.sub.2aa+1  S7
—X-alkyl-CHPCHP-C.sub.aaH.sub.2aa+1  S8 in which P is as defined in formula I, alkyl denotes a single bond or straight-chain or branched alkylene having 1 to 12 C atoms which is unsubstituted or mono- or polysubstituted by F, Cl or CN and in which one or more non-adjacent CH.sub.2 groups may each, independently of one another, be replaced by —C(R.sup.0)═C(R.sup.0)—, —C≡C—, —N(R.sup.0)—, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that O and/or S atoms are not linked directly to one another, where R.sup.0 has the meaning indicated above, aa and bb each, independently of one another, denote 0, 1, 2, 3, 4, 5 or 6, X has one of the meanings indicated for X″, and is preferably O, CO, SO.sub.2, O—CO—, CO—O or a single bond.

(68) Preferred spacer groups Sp(P).sub.2 are selected from formulae S1, S2 and S3.

(69) Very preferred spacer groups Sp(P).sub.2 are selected from the following subformulae:
—CHPP  S1a
—O—CHPP  S1b
—CH.sub.2—CHPP  S1c
—OCH.sub.2—CHPP  S1d
—CH(CH.sub.2—P)(CH.sub.2—P)  S2a
—OCH(CH.sub.2—P)(CH.sub.2—P)  S2b
—CH.sub.2—CH(CH.sub.2—P)(CH.sub.2—P)  S2c
—OCH.sub.2—CH(CH.sub.2—P)(CH.sub.2—P)  S2d
—CO—NH((CH.sub.2).sub.2P)((CH.sub.2).sub.2P)  S3a

(70) In the compounds of formula I and its subformulae as described above and below, P is preferably selected from the group consisting of vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, most preferably from acrylate and methacrylate.

(71) Further preferred are compounds of formula I and its subformulae as described above and below, wherein all polymerisable groups P that are present in the compound have the same meaning, and very preferably denote acrylate or methacrylate, most preferably methacrylate.

(72) In the compounds of formula I and its subformulae as described above and below, R preferably denotes P-Sp-.

(73) Further preferred are compounds of formula I and its subformulae as described above and below, wherein Sp denotes a single bond or —(CH.sub.2).sub.p1—, —O—(CH.sub.2).sub.p1—, —O—CO—(CH.sub.2).sub.p1, or —CO—O—(CH.sub.2).sub.p1, wherein p1 is 2, 3, 4, 5 or 6, and, if Sp is —O—(CH.sub.2).sub.p1—, —O—CO—(CH.sub.2).sub.p1 or —CO—O—(CH.sub.2).sub.p1 the O-atom or CO-group, respectively, is linked to the benzene ring.

(74) Further preferred are compounds of formula I and its subformulae as described above and below, wherein at least one group Sp is a single bond.

(75) Further preferred are compounds of formula I and its subformulae as described above and below, wherein at least one group Sp is different from a single bond, and is preferably selected from —(CH.sub.2).sub.p1—, —O—(CH.sub.2).sub.p1—, —O—CO—(CH.sub.2).sub.p1, or —CO—O—(CH.sub.2).sub.p1, wherein p1 is 2, 3, 4, 5 or 6, and, if Sp is —O(CH.sub.2).sub.p1—, —O—CO—(CH.sub.2).sub.p1 or —CO—O—(CH.sub.2).sub.p1 the O-atom or CO-group, respectively, is linked to the benzene ring.

(76) Very preferred groups -A.sup.1-(Z-A.sup.2).sub.z- in formula I are selected from the following formulae

(77) ##STR00011##
wherein at least one benzene ring is are substituted by at last one group L.sup.11 and the benzene rings are optionally further substituted by one or more groups L or P-Sp-.

(78) Preferred compounds of formula I are selected from the following subformulae

(79) ##STR00012##
wherein P, Sp, R and L have the meanings given in formula I,
r1, r3 are independently of each other 0, 1, 2 or 3,
r2 is 0, 1, 2, 3 or 4,
r4, r5, r6 are independently of each other 0, 1 or 2,
wherein r1+r6≥1, r1+r2+r3≥1, r4+r5≥1, r1+r3+r4≥1, and at least one group L denotes —CH.sub.2—O—CH.sub.3, and
wherein in formula I1 at least one of the groups Sp is a single bond.

(80) Preferred are compounds of formula I1-I5 wherein one of the two groups R is H and the other is P-Sp.

(81) Further preferred are compounds of formula I1-I5 wherein both groups R denote H.

(82) Further preferred are compounds of formula I1-I5 wherein both groups R denote P-Sp.

(83) Very preferred are compounds of formula I1, I2 and I5.

(84) Very preferred compounds of formula I and I1-I5 are selected from the following subformulae:

(85) ##STR00013## ##STR00014## ##STR00015##
wherein P, Sp, P(Sp).sub.2, L, r1-r6 have the meanings given in formula I and I1-I5, and at least one group L denotes —CH.sub.2—O—CHs, and wherein in formulae I1-1 to I1-4 at least one of the groups Sp is a single bond.

(86) Very preferred compounds of formula I are selected from the following subformulae:

(87) ##STR00016## ##STR00017## ##STR00018## ##STR00019## ##STR00020## ##STR00021## ##STR00022## ##STR00023## ##STR00024## ##STR00025## ##STR00026## ##STR00027## ##STR00028## ##STR00029## ##STR00030## ##STR00031## ##STR00032##

(88) Wherein L.sup.a is —CH.sub.2—O—CHs, P, Sp and Sp(P).sub.2 have the meanings given above or below, with Sp preferably being different from a single bond, and L′ has one of the meanings given for L above or below that is preferably different from L.sup.a.

(89) Preferred compounds of formula I1 to I5, I1-1 to I5-5 and I1-1-1 to I5-5-7 are those wherein all groups Sp denote a single bond.

(90) Further preferred compounds of formula I1 to I5, I1-1 to I5-5 and I1-1-1 to I5-5-7 are those wherein at least one of the groups Sp is a single bond and at least one of the groups Sp is different from a single bond.

(91) Preferred compounds of formula I and II and their subformulae are selected from the following preferred embodiments, including any combination thereof: All groups P in the compound have the same meaning, A.sup.1-(Z-A.sup.2).sub.z- is selected from formulae A1, A2 and A5, the compounds contain exactly two polymerizable groups (represented by the groups P), the compounds contain exactly three polymerizable groups (represented by the groups P), P is selected from the group consisting of acrylate, methacrylate and oxetane, very preferably acrylate or methacrylate, P is methacrylate, all groups Sp are a single bond, at least one of the groups Sp is a single bond and at least one of the groups Sp is different from a single bond, Sp, when being different from a single bond, is —(CH.sub.2).sub.p2—, —(CH.sub.2).sub.p2—O—, —(CH.sub.2).sub.p2—CO—O—, —(CH.sub.2).sub.p2—O—CO—, wherein p2 is 2, 3, 4, 5 or 6, and the O-atom or the CO-group, respectively, is connected to the benzene ring, Sp is a single bond or denotes —(CH.sub.2).sub.p2—, —(CH.sub.2).sub.p2—O—, —(CH.sub.2).sub.p2—CO—O—, —(CH.sub.2).sub.p2—O—CO—, wherein p2 is 2, 3, 4, 5 or 6, and the O-atom or the CO-group, respectively, is connected to the benzene ring, Sp(P).sub.2 is selected from subformulae S11-S31, R denotes P-Sp-, R does not denote or contain a polymerizable group, R does not denote or contain a polymerizable group and denotes straight chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F, Cl or L.sup.a, L or L′, when being different from L.sup.11, denote F, Cl or CN, L′ is F, r1, r2 and r3 denote 0 or 1, r1, r2, r3, r4, r5 and r6 denote 0 or 1, one of r1 and r6 is 0 and the other is 1, r1 is 1, and r2 and r3 are 0, r3 is 1 and r1 and r2 are 0, one of r4 and r5 is 0 and the other is 1, r1 and r4 are 0 and r3 is 1, r1 and r3 are 0 and r4 is 1, r3 and r4 are 0 and r1 is 1,

(92) Preferred compounds of formula II are those selected from the above preferred subformulae I1 to I5, I1-1 to I5-5 and I1-1-1 to I5-5-7, wherein P is replaced by Pg as defined in formula II.

(93) Suitable protected hydroxyl groups Pg for use in compounds of formula II and its subformulae are known to the person skilled in the art. Preferred protecting groups for hydroxyl groups are alkyl, alkoxyalkyl, acyl, alkylsilyl, arylsilyl and arylmethyl groups, especially 2-tetrahydropyranyl, methoxymethyl, methoxyethoxymethyl, acetyl, triisopropylsilyl, tert-butyldimethylsilyl or benzyl.

(94) The term “masked hydroxyl group” is understood to mean any functional group that can be chemically converted into a hydroxyl group. Suitable masked hydroxyl groups Pg are known to the person skilled in the art.

(95) The compounds of formula II are suitable as intermediates for the preparation of compounds of the formula I and its subformulae.

(96) The invention further relates to the use of the compounds of formula II as intermediates for the preparation of compounds of the formula I and its subformulae.

(97) The compounds and intermediates of the formulae I and II and sub-formulae thereof can be prepared analogously to processes known to the person skilled in the art and described in standard works of organic chemistry, such as, for example, in Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Thieme-Verlag, Stuttgart.

(98) For example, compounds of formula I can be synthesised by esterification or etherification of the intermediates of formula II, wherein Pg denotes OH, using corresponding acids, acid derivatives, or halogenated compounds containing a polymerisable group P.

(99) For example, acrylic or methacrylic esters can be prepared by esterification of the corresponding alcohols with acid derivatives like, for example, (meth)acryloyl chloride or (meth)acrylic anhydride in the presence of a base like pyridine or triethyl amine, and 4-(N,N-dimethylamino)pyridine (DMAP). Alternatively the esters can be prepared by esterification of the alcohols with (meth)acrylic acid in the presence of a dehydrating reagent, for example according to Steglich with dicyclohexylcarbodiimide (DCC), N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) or N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride and DMAP.

(100) Further suitable methods are shown in the examples.

(101) For the production of PSA displays, the polymerisable compounds contained in the LC medium are polymerised or crosslinked (if one compound contains two or more polymerisable groups) by in-situ polymerisation in the LC medium between the substrates of the LC display, optionally while a voltage is applied to the electrodes.

(102) The structure of the PSA displays according to the invention corresponds to the usual geometry for PSA displays, as described in the prior art cited at the outset. Geometries without protrusions are preferred, in particular those in which, in addition, the electrode on the colour filter side is unstructured and only the electrode on the TFT side has slots. Particularly suitable and preferred electrode structures for PS-VA displays are described, for example, in US 2006/0066793 A1.

(103) A preferred PSA type LC display of the present invention comprises: a first substrate including a pixel electrode defining pixel areas, the pixel electrode being connected to a switching element disposed in each pixel area and optionally including a micro-slit pattern, and optionally a first alignment layer disposed on the pixel electrode, a second substrate including a common electrode layer, which may be disposed on the entire portion of the second substrate facing the first substrate, and optionally a second alignment layer, an LC layer disposed between the first and second substrates and including an LC medium comprising a polymerisable component A and a liquid crystal component B as described above and below, wherein the polymerisable component A may also be polymerised.

(104) The first and/or second alignment layer controls the alignment direction of the LC molecules of the LC layer. For example, in PS-VA displays the alignment layer is selected such that it imparts to the LC molecules homeotropic (or vertical) alignment (i.e. perpendicular to the surface) or tilted alignment. Such an alignment layer may for example comprise a polyimide, which may also be rubbed, or may be prepared by a photoalignment method.

(105) The LC layer with the LC medium can be deposited between the substrates of the display by methods that are conventionally used by display manufacturers, for example the so-called one-drop-filling (ODF) method. The polymerisable component of the LC medium is then polymerised for example by UV photopolymerisation. The polymerisation can be carried out in one step or in two or more steps.

(106) The PSA display may comprise further elements, like a colour filter, a black matrix, a passivation layer, optical retardation layers, transistor elements for addressing the individual pixels, etc., all of which are well known to the person skilled in the art and can be employed without inventive skill.

(107) The electrode structure can be designed by the skilled person depending on the individual display type. For example for PS-VA displays a multi-domain orientation of the LC molecules can be induced by providing electrodes having slits and/or bumps or protrusions in order to create two, four or more different tilt alignment directions.

(108) Upon polymerisation the polymerisable compounds form a crosslinked polymer, which causes a certain pretilt of the LC molecules in the LC medium. Without wishing to be bound to a specific theory, it is believed that at least a part of the crosslinked polymer, which is formed by the polymerisable compounds, will phase-separate or precipitate from the LC medium and form a polymer layer on the substrates or electrodes, or the alignment layer provided thereon. Microscopic measurement data (like SEM and AFM) have confirmed that at least a part of the formed polymer accumulates at the LC/substrate interface.

(109) The polymerisation can be carried out in one step. It is also possible firstly to carry out the polymerisation, optionally while applying a voltage, in a first step in order to produce a pretilt angle, and subsequently, in a second polymerisation step without an applied voltage, to polymerise or crosslink the compounds which have not reacted in the first step (“end curing”).

(110) Suitable and preferred polymerisation methods are, for example, thermal or photopolymerisation, preferably photopolymerisation, in particular UV induced photopolymerisation, which can be achieved by exposure of the polymerisable compounds to UV radiation.

(111) Optionally one or more polymerisation initiators are added to the LC medium. 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 Darocure1173® (Ciba AG). If a polymerisation initiator is employed, its proportion is preferably 0.001 to 5% by weight, particularly preferably 0.001 to 1% by weight.

(112) The polymerisable compounds according to the invention are also suitable for polymerisation without an initiator, which is accompanied by considerable advantages, such, for example, lower material costs and in particular less 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 the addition of an initiator. In a preferred embodiment, the LC medium thus does not contain a polymerisation initiator.

(113) The the LC medium 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 (Ciba AG), such as, for example, Irganox® 1076. If stabilisers are employed, their proportion, based on the total amount of RMs or the polymerisable component (component A), is preferably 10-500,000 ppm, particularly preferably 50-50,000 ppm.

(114) The polymerisable compounds of formula I do in particular show good UV absorption in, and are therefore especially suitable for, a process of preparing a PSA display including one or more of the following features: the polymerisable medium is exposed to UV light in the display in a 2-step process, including a first UV exposure step (“UV-1 step”) to generate the tilt angle, and a second UV exposure step (“UV-2 step”) to finish polymerization, the polymerisable medium is exposed to UV light in the display generated by an energy-saving UV lamp (also known as “green UV lamps”). These lamps are characterized by a relative low intensity ( 1/100- 1/10 of a conventional UV1 lamp) in their absorption spectra from 300-380 nm, and are preferably used in the UV2 step, but are optionally also used in the UV1 step when avoiding high intensity is necessary for the process. the polymerisable medium is exposed to UV light in the display generated by a UV lamp with a radiation spectrum that is shifted to longer wavelengths, preferably 340 nm or more, to avoid short UV light exposure in the PS-VA process.

(115) Both using lower intensity and a UV shift to longer wavelengths protect the organic layer against damage that may be caused by the UV light.

(116) A preferred embodiment of the present invention relates to a process for preparing a PSA display as described above and below, comprising one or more of the following features: the polymerisable LC medium is exposed to UV light in a 2-step process, including a first UV exposure step (“UV-1 step”) to generate the tilt angle, and a second UV exposure step (“UV-2 step”) to finish polymerization, the polymerisable LC medium is exposed to UV light generated by a UV lamp having an intensity of from 0.5 mW/cm.sup.2 to 10 mW/cm.sup.2 in the wavelength range from 300-380 nm, preferably used in the UV2 step, and optionally also in the UV1 step, the polymerisable LC medium is exposed to UV light having a wavelength of 340 nm or more, and preferably 400 nm or less.

(117) This preferred process can be carried out for example by using the desired UV lamps or by using a band pass filter and/or a cut-off filter, which are substantially transmissive for UV light with the respective desired wavelength(s) and are substantially blocking light with the respective undesired wavelengths. For example, when irradiation with UV light of wavelengths λ of 300-400 nm is desired, UV exposure can be carried out using a wide band pass filter being substantially transmissive for wavelengths 300 nm<λ<400 nm. When irradiation with UV light of wavelength λ of more than 340 nm is desired, UV exposure can be carried out using a cut-off filter being substantially transmissive for wavelengths λ>340 nm.

(118) “Substantially transmissive” means that the filter transmits a substantial part, preferably at least 50% of the intensity, of incident light of the desired wavelength(s). “Substantially blocking” means that the filter does not transmit a substantial part, preferably at least 50% of the intensity, of incident light of the undesired wavelengths. “Desired (undesired) wavelength” e.g. in case of a band pass filter means the wavelengths inside (outside) the given range of λ, and in case of a cut-off filter means the wavelengths above (below) the given value of λ.

(119) This preferred process enables the manufacture of displays by using longer UV wavelengths, thereby reducing or even avoiding the hazardous and damaging effects of short UV light components.

(120) UV radiation energy is in general from 6 to 100 J, depending on the production process conditions.

(121) Preferably the LC medium according to the present invention does essentially consist of a polymerisable component A), or one or more polymerisable compounds of formula I, and an LC component B), or LC host mixture, as described above and below. However, the LC medium may additionally comprise one or more further components or additives, preferably selected from the list including but not limited to co-monomers, chiral dopants, polymerisation initiators, inhibitors, stabilizers, surfactants, wetting agents, lubricating agents, dispersing agents, hydrophobing agents, adhesive agents, flow improvers, defoaming agents, deaerators, diluents, reactive diluents, auxiliaries, colourants, dyes, pigments and nanoparticles.

(122) Particular preference is given to LC media comprising one, two or three polymerisable compounds of formula I.

(123) Preference is furthermore given to LC media in which the polymerisable component A) comprises exclusively polymerisable compounds of formula I.

(124) Preference is furthermore given to LC media in which the liquid-crystalline component B) or the LC host mixture has a nematic LC phase, and preferably has no chiral liquid crystal phase.

(125) The LC component B), or LC host mixture, is preferably a nematic LC mixture.

(126) Preference is furthermore given to achiral compounds of formula I, and to LC media in which the compounds of component A and/or B are selected exclusively from the group consisting of achiral compounds.

(127) Preferably the proportion of the polymerisable component A) in the LC medium is from >0 to <5%, very preferably from >0 to <1%, most preferably from 0.01 to 0.5%.

(128) Preferably the proportion of compounds of formula I in the LC medium is from >0 to <5%, very preferably from >0 to <1%, most preferably from 0.01 to 0.5%.

(129) Preferably the proportion of the LC component B) in the LC medium is from 95 to <100%, very preferably from 99 to <100%.

(130) In a preferred embodiment the polymerisable compounds of the polymerisable component B) are exclusively selected from formula I.

(131) In another preferred embodiment the polymerisable component B) comprises, in addition to the compounds of formula I, one or more further polymerisable compounds (“co-monomers”), preferably selected from RMs.

(132) Suitable and preferred mesogenic comonomers are selected from the following formulae:

(133) ##STR00033## ##STR00034## ##STR00035## ##STR00036## ##STR00037##
in which the individual radicals have the following meanings: P.sup.1, P.sup.2 and P.sup.3 each, independently of one another, denote an acrylate or methacrylate group, Sp.sup.1, Sp.sup.2 and Sp.sup.3 each, independently of one another, denote a single bond or a spacer group having one of the meanings indicated above and below for Sp, and particularly preferably denote —(CH.sub.2).sub.p1—, —(CH.sub.2).sub.p1—O—, —(CH.sub.2).sub.p1—CO—O—, —(CH.sub.2).sub.p1—O—CO— or —(CH.sub.2).sub.p1—O—CO—O—, in which p1 is an integer from 1 to 12, where, in addition, one or more of the radicals P.sup.1-Sp.sup.1-, P.sup.1-Sp.sup.2- and P.sup.3-Sp.sup.3- may denote R.sup.aa, with the proviso that at least one of the radicals P.sup.1-Sp.sup.1-, P.sup.2-Sp.sup.2 and P.sup.3-Sp.sup.3- present is different from R.sup.aa, R.sup.aa denotes H, F, Cl, CN or straight-chain or branched alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced, independently of one another, by C(R.sup.0)═C(R.sup.00)—, —C≡C—, —N(R.sup.0)—, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that O and/or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F, Cl, CN or P.sup.1-Sp.sup.1-, particularly preferably straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms (where the alkenyl and alkynyl radicals have at least two C atoms and the branched radicals have at least three C atoms), R.sup.0, R.sup.00 each, independently of one another and identically or differently on each occurrence, denote H or alkyl having 1 to 12 C atoms, R.sup.y and R.sup.z each, independently of one another, denote H, F, CH.sub.3 or CF.sub.3, X.sup.1, X.sup.2 and X.sup.3 each, independently of one another, denote —CO—O—, —O—CO— or a single bond, Z.sup.1 denotes —O—, —CO—, —C(R.sup.yR.sup.z)— or —CF.sub.2CF.sub.2—, Z.sup.2 and Z.sup.3 each, independently of one another, denote —CO—O—, —O—CO—, —CH.sub.2O—, —OCH.sub.2—, —CF.sub.2O—, —OCF.sub.2— or —(CH.sub.2).sub.n−, where n is 2, 3 or 4, L on each occurrence, identically or differently, denotes F, Cl, CN or straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, preferably F, L′ and L″ each, independently of one another, denote H, F or Cl, r denotes 0, 1, 2, 3 or 4, s denotes 0, 1, 2 or 3, t denotes 0, 1 or 2, x denotes 0 or 1.

(134) Especially preferred are compounds of formulae M2, M13, M17, M22, M23, M24 and M30.

(135) Further preferred are trireactive compounds M15 to M30, in particular M17, M18, M19, M22, M23, M24, M25, M26, M30 and M31.

(136) In the compounds of formulae M1 to M31 the group

(137) ##STR00038##
is preferably

(138) ##STR00039##
wherein L on each occurrence, identically or differently, has one of the meanings given above or below, and is preferably F, Cl, CN, NO.sub.2, CH.sub.3, C.sub.2H.sub.5, C(CH.sub.3).sub.3, CH(CH.sub.3).sub.2, CH.sub.2CH(CH.sub.3)C.sub.2H.sub.5, OCH.sub.3, OC.sub.2H.sub.5, COCH.sub.3, COC.sub.2H.sub.5, COOCH.sub.3, COOC.sub.2H.sub.5, CF.sub.3, OCF.sub.3, OCHF.sub.2, OC.sub.2F.sub.5 or P-Sp-, very preferably F, Cl, CN, CH.sub.3, C.sub.2H.sub.5, OCH.sub.3, COCH.sub.3, OCF.sub.3 or P-Sp-, more preferably F, Cl, CH.sub.3, OCH.sub.3, COCH.sub.3 oder OCF.sub.3, especially F or CH.sub.3.

(139) Besides the polymerisable compounds described above, the LC media for use in the LC displays according to the invention comprise an LC mixture (“host mixture”) comprising one or more, preferably two or more LC compounds which are selected from low-molecular-weight compounds that are unpolymerisable. These LC compounds are selected such that they stable and/or unreactive to a polymerisation reaction under the conditions applied to the polymerisation of the polymerisable compounds.

(140) In principle, any LC mixture which is suitable for use in conventional displays is suitable as host mixture. Suitable LC mixtures are known to the person skilled in the art and are described in the literature, for example mixtures in VA displays in EP 1 378 557 A1 and mixtures for OCB displays in EP 1 306 418 A1 and DE 102 24 046 A1.

(141) The polymerisable compounds of formula I are especially suitable for use in an LC host mixture that comprises one or more mesogenic or LC compounds comprising an alkenyl group (hereinafter also referred to as “alkenyl compounds”), wherein said alkenyl group is stable to a polymerisation reaction under the conditions used for polymerisation of the compounds of formula I and of the other polymerisable compounds contained in the LC medium. Compared to RMs known from prior art the compounds of formula I do in such an LC host mixture exhibit improved properties, like solubility, reactivity or capability of generating a tilt angle.

(142) Thus, in addition to the polymerisable compounds of formula I, the LC medium according to the present invention comprises one or more mesogenic or liquid crystalline compounds comprising an alkenyl group, (“alkenyl compound”), where this alkenyl group is preferably stable to a polymerisation reaction under the conditions used for the polymerisation of the polymerisable compounds of formula I or of the other polymerisable compounds contained in the LC medium.

(143) The alkenyl groups in the alkenyl compounds are preferably selected from straight-chain, branched or cyclic alkenyl, in particular having 2 to 25 C atoms, particularly preferably having 2 to 12 C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that O and/or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F and/or C.sub.1.

(144) Preferred alkenyl groups are straight-chain alkenyl having 2 to 7 C atoms and cyclohexenyl, in particular ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, 1,4-cyclohexen-1-yl and 1,4-cyclohexen-3-yl.

(145) The concentration of compounds containing an alkenyl group in the LC host mixture (i.e. without any polymerisable compounds) is preferably from 5% to 100%, very preferably from 20% to 60%.

(146) Especially preferred are LC mixtures containing 1 to 5, preferably 1, 2 or 3 compounds having an alkenyl group.

(147) The mesogenic and LC compounds containing an alkenyl group are preferably selected from formulae AN and AY as defined below.

(148) Besides the polymerisable component A) as described above, the LC media according to the present invention comprise an LC component B), or LC host mixture, comprising one or more, preferably two or more LC compounds which are selected from low-molecular-weight compounds that are unpolymerisable. These LC compounds are selected such that they stable and/or unreactive to a polymerisation reaction under the conditions applied to the polymerisation of the polymerisable compounds.

(149) In a first preferred embodiment the LC medium contains an LC component B), or LC host mixture, based on compounds with negative dielectric anisotropy. Such LC media are especially suitable for use in PS-VA and PS-UB-FFS displays. Particularly preferred embodiments of such an LC medium are those of sections a)-z3) below: a) LC medium wherein the component B) or LC host mixture comprises one or more compounds selected from formulae CY and PY:

(150) ##STR00040## wherein a denotes 1 or 2, b denotes 0 or 1,

(151) ##STR00041##
denotes

(152) ##STR00042## 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, 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, 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.

(153) 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.

(154) The compounds of the formula CY are preferably selected from the group consisting of the following sub-formulae:

(155) ##STR00043## ##STR00044## ##STR00045## ##STR00046##
in which 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—.

(156) The compounds of the formula PY are preferably selected from the group consisting of the following sub-formulae:

(157) ##STR00047## ##STR00048## ##STR00049##
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, 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—. b) LC medium wherein the component B) or LC host mixture comprises one or more mesogenic or LC compounds comprising an alkenyl group (hereinafter also referred to as “alkenyl compounds”), wherein said alkenyl group is stable to a polymerisation reaction under the conditions used for polymerisation of the polymerisable compounds contained in the LC medium.

(158) Preferably the component B) or LC host mixture comprises one or more alkenyl compounds selected from formulae AN and AY

(159) ##STR00050##
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning:

(160) ##STR00051## R.sup.A1 alkenyl having 2 to 9 C atoms or, if at least one of the rings X, Y and Z denotes cyclohexenyl, also one of the meanings of R.sup.A2, R.sup.A2 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—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, Z.sup.x —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, L.sup.1,2 H, F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F or CHF.sub.2H, preferably H, F or Cl, x 1 or 2, z 0 or 1.

(161) Preferred compounds of formula AN and AY are those wherein R.sup.A2 is selected from ethenyl, propenyl, butenyl, pentenyl, hexenyl and heptenyl.

(162) In a preferred embodiment the component B) or LC host mixture comprises one or more compounds of formula AN selected from the following sub-formulae:

(163) ##STR00052##
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 2-7 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—.

(164) Preferably the the component B) or LC host mixture comprises one or more compounds selected from formulae AN1, AN2, AN3 and AN6, very preferably one or more compounds of formula AN1.

(165) In another preferred embodiment the component B) or LC host mixture comprises one or more compounds of formula AN selected from the following sub-formulae:

(166) ##STR00053##
in which m denotes 1, 2, 3, 4, 5 or 6, i denotes 0, 1, 2 or 3, and R.sup.b1 denotes H, CH.sub.3 or C.sub.2H.sub.5.

(167) In another preferred embodiment the component B) or LC host mixture comprises one or more compounds selected from the following subformulae:

(168) ##STR00054##

(169) Most preferred are compounds of formula AN1a2 and AN1a5.

(170) In another preferred embodiment the component B) or LC host mixture comprises one or more compounds of formula AY selected from the following sub-formulae:

(171) ##STR00055## ##STR00056##
in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, “(O)” denotes an O-atom or a single bond, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-7 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.2—CH═CH—(CH.sub.2).sub.2.

(172) In another preferred embodiment the component B) or LC host mixture comprises one or more compounds of formula AY selected from the following sub-formulae:

(173) ##STR00057##
in which m and n each, independently of one another, denote 1, 2, 3, 4, 5 or 6, and alkenyl 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—.

(174) Preferably the proportion of compounds of formula AN and AY in the LC medium is from 2 to 70% by weight, very preferably from 5 to 60% by weight, most preferably from 10 to 50% by weight.

(175) Preferably the LC medium or LC host mixture contains 1 to 5, preferably 1, 2 or 3 compounds selected from formulae AN and AY.

(176) In another preferred embodiment of the present invention the LC medium comprises one or more compounds of formula AY14, very preferably of AY14a. The proportion of compounds of formula AY14 or AY14a in the LC medium is preferably 3 to 20% by weight.

(177) The addition of alkenyl compounds of formula AN and/or AY enables a reduction of the viscosity and response time of the LC medium. c) LC medium wherein the component B) or LC host mixture comprises one or more compounds of the following formula:

(178) ##STR00058##
in which the individual radicals have the following meanings:

(179) ##STR00059##
denotes

(180) ##STR00060##
denotes

(181) ##STR00061## 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, preferably a single bond.

(182) The compounds of the formula ZK are preferably selected from the group consisting of the following sub-formulae:

(183) ##STR00062##
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—.

(184) Especially preferred are compounds of formula ZK1.

(185) Particularly preferred compounds of formula ZK are selected from the following sub-formulae:

(186) ##STR00063##
wherein the propyl, butyl and pentyl groups are straight-chain groups.

(187) Most preferred are compounds of formula ZK1a. d) LC medium wherein component B) or the LC host mixture additionally comprises one or more compounds of the following formula:

(188) ##STR00064##
in which the individual radicals on each occurrence, identically or differently, have the following meanings: 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 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,

(189) ##STR00065##
denotes

(190) ##STR00066##
denotes

(191) ##STR00067##
and e denotes 1 or 2.

(192) The compounds of the formula DK are preferably selected from the group consisting of the following sub-formulae:

(193) ##STR00068##
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—. e) LC medium wherein component B) or the LC host mixture additionally comprises one or more compounds of the following formula:

(194) ##STR00069##
in which the individual radicals have the following meanings:

(195) ##STR00070##
denotes

(196) ##STR00071##
with at least one ring F being different from cyclohexylene, f denotes 1 or 2, 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, Z.sup.x 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, 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.

(197) 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.

(198) The compounds of the formula LY are preferably selected from the group consisting of the following sub-formulae:

(199) ##STR00072## ##STR00073## ##STR00074##
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—. f) LC medium wherein component B) or the LC host mixture additionally comprises one or more compounds selected from the group consisting of the following formulae:

(200) ##STR00075##
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. g) LC medium wherein component B) or the LC host mixture additionally comprises one or more compounds selected from the group consisting of the following formulae:

(201) ##STR00076## ##STR00077##
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. h) LC medium wherein component B) or the LC host mixture additionally comprises one or more biphenyl compounds selected from the group consisting of the following formulae:

(202) ##STR00078##
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—.

(203) The proportion of the biphenyls of the formulae B1 to B3 in the LC host mixture is preferably at least 3% by weight, in particular 5% by weight.

(204) The compounds of the formula B2 are particularly preferred.

(205) The compounds of the formulae B1 to B3 are preferably selected from the group consisting of the following sub-formulae:

(206) ##STR00079##
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 B2c. i) LC medium wherein component B) or the LC host mixture additionally comprises one or more terphenyl compounds of the following formula:

(207) ##STR00080##
in which R.sup.5 and R.sup.6 each, independently of one another, have one of the meanings indicated above, and

(208) ##STR00081##
each, independently of one another, denote

(209) ##STR00082##
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.

(210) The compounds of the formula T are preferably selected from the group consisting of the following sub-formulae:

(211) ##STR00083## ##STR00084## ##STR00085## ##STR00086##
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—.

(212) R preferably denotes methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentoxy.

(213) The LC host mixture 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.

(214) 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.

(215) The terphenyls are preferably employed in LC media according to the invention if the Δn value of the mixture is to be 0.1. Preferred LC media 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. k) LC medium wherein component B) or the LC host mixture additionally comprises one or more quaterphenyl compounds selected from the group consisting of the following formulae:

(216) ##STR00087##
wherein R.sup.Q is alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated, X.sup.Q is F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, L.sup.Q1 to L.sup.Q6 independently of each other are H or F, with at least one of L.sup.Q1 to L.sup.Q6 being F.

(217) Preferred compounds of formula Q are those wherein R.sup.Q denotes straight-chain alkyl with 2 to 6 C-atoms, very preferably ethyl, n-propyl or n-butyl.

(218) Preferred compounds of formula Q are those wherein L.sup.Q3 and L.sup.Q4 are F. Further preferred compounds of formula Q are those wherein L.sup.Q3, L.sup.Q4 and one or two of L.sup.Q1 and L.sup.Q2 are F.

(219) Preferred compounds of formula Q are those wherein X.sup.Q denotes F or OCF.sub.3, very preferably F.

(220) The compounds of formula Q are preferably selected from the following subformulae

(221) ##STR00088##
wherein R.sup.Q has one of the meanings of formula Q or one of its preferred meanings given above and below, and is preferably ethyl, n-propyl or n-butyl.

(222) Especially preferred are compounds of formula Q1, in particular those wherein R.sup.Q is n-propyl.

(223) Preferably the proportion of compounds of formula Q in the LC host mixture is from >0 to ≤5% by weight, very preferably from 0.1 to 2% by weight, most preferably from 0.2 to 1.5% by weight.

(224) Preferably the LC host mixture contains 1 to 5, preferably 1 or 2 compounds of formula Q.

(225) The addition of quaterphenyl compounds of formula Q to the LC host mixture enables to reduce ODF mura, whilst maintaining high UV absorption, enabling quick and complete polymerisation, enabling strong and quick tilt angle generation, and increasing the UV stability of the LC medium.

(226) Besides, the addition of compounds of formula Q, which have positive dielectric anisotropy, to the LC medium with negative dielectric anisotropy allows a better control of the values of the dielectric constants ε.sub.∥ and ε.sub.⊥, and in particular enables to achieve a high value of the dielectric constant ε.sub.∥ while keeping the dielectric anisotropy Δε constant, thereby reducing the kick-back voltage and reducing image sticking. l) LC medium wherein component B) or the LC host mixture additionally comprises one or more compounds of formula C:

(227) ##STR00089##
wherein R.sup.C denotes alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated, X.sup.C denotes F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, L.sup.C1, L.sup.C2 independently of each other denote H or F, with at least one of L.sup.C1 and L.sup.C2 being F.

(228) Preferred compounds of formula C are those wherein R.sup.C denotes straight-chain alkyl with 2 to 6 C-atoms, very preferably ethyl, n-propyl or n-butyl.

(229) Preferred compounds of formula C are those wherein L.sup.C1 and L.sup.C2 are F.

(230) Preferred compounds of formula C are those wherein X.sup.C denotes F or OCF.sub.3, very preferably F.

(231) Preferred compounds of formula C are selected from the following formula

(232) ##STR00090##
wherein R.sup.C has one of the meanings of formula C or one of its preferred meanings given above and below, and is preferably ethyl, n-propyl or n-butyl, very preferably n-propyl.

(233) Preferably the proportion of compounds of formula C in the LC host mixture is from >0 to ≤10% by weight, very preferably from 0.1 to 8% by weight, most preferably from 0.2 to 5% by weight.

(234) Preferably the LC host mixture contains 1 to 5, preferably 1, 2 or 3 compounds of formula C.

(235) The addition of compounds of formula C, which have positive dielectric anisotropy, to the LC medium with negative dielectric anisotropy allows a better control of the values of the dielectric constants ε.sub.∥ and ε.sub.⊥, and in particular enables to achieve a high value of the dielectric constant ε.sub.∥ while keeping the dielectric anisotropy Δε constant, thereby reducing the kick-back voltage and reducing image sticking. Besides, the addition of compounds of formula C enables to reduce the viscosity and the response time of the LC medium. m) LC medium wherein component B) or the LC host mixture additionally comprises one or more compounds selected from the group consisting of the following formulae:

(236) ##STR00091##
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.

(237) Preferred media comprise one or more compounds selected from the formulae O1, O3 and O4. n) LC medium wherein component B) or the LC host mixture additionally comprises one or more compounds of the following formula:

(238) ##STR00092##
in which

(239) ##STR00093##
denotes

(240) ##STR00094##
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.

(241) Particularly preferred compounds of the formula FI are selected from the group consisting of the following sub-formulae:

(242) ##STR00095##
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. o) LC medium wherein component B) or the LC host mixture additionally comprises one or more compounds selected from the group consisting of the following formulae:

(243) ##STR00096##
in which R.sup.9 has the meaning indicated for R.sup.1, and alkyl denotes a straight-chain alkyl radical having 1-6 C atoms. p) LC medium wherein component B) or the LC host mixture 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:

(244) ##STR00097## ##STR00098## in which 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, 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 Z.sup.1 and Z.sup.2 each, independently of one another, denote —C.sub.2H.sub.4—, —CH═CH—, —(CH.sub.2).sub.4—, —(CH.sub.2).sub.3O—, —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—, —CO—O—, —O—CO—, —C.sub.2F.sub.4—, —CF═CF—, —CF═CH—, —CH═CF—, —CH.sub.2— or a single bond. q) LC medium wherein component B) or the LC host mixture additionally comprises one or more difluorodibenzochromans and/or chromans of the following formulae:

(245) ##STR00099##
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, ring M is trans-1,4-cyclohexylene or 1,4-phenylene, Z.sup.m —C.sub.2H.sub.4—, —CH.sub.2O—, —OCH.sub.2—, —CO—O— or —O—CO—, c is 0, 1 or 2, preferably in amounts of 3 to 20% by weight, in particular in amounts of 3 to 15% by weight.

(246) Particularly preferred compounds of the formulae BC, CR and RC are selected from the group consisting of the following sub-formulae:

(247) ##STR00100## ##STR00101## ##STR00102##
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—.

(248) Very particular preference is given to LC host mixtures comprising one, two or three compounds of the formula BC-2. r) LC medium wherein component B) or the LC host mixture additionally comprises one or more fluorinated phenanthrenes and/or dibenzofurans of the following formulae:

(249) ##STR00103##
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, b denotes 0 or 1, L denotes F, and r denotes 1, 2 or 3.

(250) Particularly preferred compounds of the formulae PH and BF are selected from the group consisting of the following sub-formulae:

(251) ##STR00104##
in which R and R′ each, independently of one another, denote a straight-chain alkyl or alkoxy radical having 1-7 C atoms. s) LC medium wherein component B) or the LC host mixture additionally comprises one or more monocyclic compounds of the following formula

(252) ##STR00105##
wherein 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, 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.

(253) 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,

(254) The compounds of the formula Y are preferably selected from the group consisting of the following sub-formulae:

(255) ##STR00106##
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—.

(256) Particularly preferred compounds of the formula Y are selected from the group consisting of the following sub-formulae:

(257) ##STR00107##
wherein Alkoxy preferably denotes straight-chain alkoxy with 3, 4, or 5 C atoms. t) LC medium which, apart from the polymerisable compounds as described above and below, does not contain a compound which contains a terminal vinyloxy group (—O—CH═CH.sub.2). u) LC medium wherein component B) or the LC host mixture 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 LC host 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%. v) LC medium wherein component B) or the LC host mixture 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 LC host 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%. w) LC medium wherein component B) or the LC host mixture 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 LC host 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%. x) LC medium in which the proportion of compounds of the formulae CY, PY and ZK in the LC host mixture as a whole is greater than 70%, preferably greater than 80%. y) LC medium in which the LC host mixture contains one or more compounds containing an alkenyl group, preferably selected from formulae AN and AY, very preferably selected from formulae AN1, AN3, AN6 and AY14, most preferably from formulae AN1a, AN3a, AN6a and AY14. The concentration of these compounds in the LC host mixture is preferably from 2 to 70%, very preferably from 3 to 55%. z) LC medium wherein component B) or the LC host mixture 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 LC host 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%. z1) LC medium wherein component B) or the LC host mixture contains one or more, preferably 1, 2 or 3, compounds selected from formulae T1, T2 and T5, very preferably from formula T2. The content of these compounds in the LC host mixture as a whole is preferably 1 to 20%. z2) LC medium in which the LC host mixture contains one or more compounds selected from formulae CY and PY, one or more compounds selected from formulae AN and AY, and one or more compounds selected from formulae T and Q. z3) LC medium in which the LC host mixture contains one or more, preferably 1, 2 or 3, compounds of formula BF1, and one or more, preferably 1, 2 or 3, compounds selected from formulae AY14, AY15 and AY16, very preferably of formula AY14. The proportion of the compounds of formula AY14-AY16 in the LC host mixture is preferably from 2 to 35%, very preferably from 3 to 30%. The proportion of the compounds of formula BF1 in the LC host mixture is preferably from 0.5 to 20%, very preferably from 1 to 15%. Further preferably the LC host mixture according to this preferred embodiment contains one or more, preferably 1, 2 or 3 compounds of formula T, preferably selected from formula T1, T2 and T5, very preferably from formula T2 or T5. The proportion of the compounds of formula T in the LC host mixture medium is preferably from 0.5 to 15%, very preferably from 1 to 10%.

(258) In a second preferred embodiment the LC medium contains an LC host mixture based on compounds with positive dielectric anisotropy. Such LC media are especially suitable for use in PS-OCB-, PS-TN-, PS-Posi-VA-, PS-IPS- or PS-FFS-displays.

(259) ##STR00108##
in which the individual radicals have, independently of each other and on each occurrence identically or differently, the following meanings:

(260) ##STR00109##
each, independently of one another, and on each occurrence, identically or differently

(261) ##STR00110## R.sup.21, R.sup.31 each, independently of one another, alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated, X.sup.0 F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, Z.sup.31 —CH.sub.2CH.sub.2—, —CF.sub.2CF.sub.2—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH.sub.2O— or a single bond, preferably —CH.sub.2CH.sub.2—, —COO—, trans-CH═CH— or a single bond, particularly preferably —COO—, trans-CH═CH— or a single bond, L.sup.21, L.sup.22, L.sup.31, L.sup.32 each, independently of one another, H or F, g 0, 1, 2 or 3.

(262) In the compounds of formula A and B, X.sup.0 is preferably F, Cl, CF.sub.3, CHF.sub.2, OCF.sub.3, OCHF.sub.2, OCFHCF.sub.3, OCFHCHF.sub.2, OCFHCHF.sub.2, OCF.sub.2CH.sub.3, OCF.sub.2CHF.sub.2, OCF.sub.2CHF.sub.2, OCF.sub.2CF.sub.2CHF.sub.2, OCF.sub.2CF.sub.2CHF.sub.2, OCFHCF.sub.2CF.sub.3, OCFHCF.sub.2CHF.sub.2, OCF.sub.2CF.sub.2CF.sub.3, OCF.sub.2CF.sub.2CClF.sub.2, OCClFCF.sub.2CF.sub.3 or CH═CF.sub.2, very preferably F or OCF.sub.3, most preferably F.

(263) In the compounds of formula A and B, R.sup.21 and R.sup.31 are preferably selected from straight-chain alkyl or alkoxy with 1, 2, 3, 4, 5 or 6 C atoms, and straight-chain alkenyl with 2, 3, 4, 5, 6 or 7 C atoms.

(264) In the compounds of formula A and B, g is preferably 1 or 2.

(265) In the compounds of formula B, Z.sup.31 is preferably COO, trans-CH═CH or a single bond, very preferably COO or a single bond.

(266) Preferably component B) of the LC medium comprises one or more compounds of formula A selected from the group consisting of the following formulae:

(267) ##STR00111##
in which A.sup.21, R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meanings given in formula A, L.sup.23 and L.sup.24 each, independently of one another, are H or F, and X.sup.0 is preferably F. Particularly preferred are compounds of formulae A1 and A2.

(268) Particularly preferred compounds of formula A1 are selected from the group consisting of the following subformulae:

(269) ##STR00112##
in which R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meaning given in formula A1, L.sup.23, L.sup.24, L.sup.25 and L.sup.26 are each, independently of one another, H or F, and X.sup.0 is preferably F.

(270) Very particularly preferred compounds of formula A1 are selected from the group consisting of the following subformulae:

(271) ##STR00113##

(272) In which R.sup.21 is as defined in formula A1.

(273) Particularly preferred compounds of formula A2 are selected from the group consisting of the following subformulae:

(274) ##STR00114## ##STR00115##
in which R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meaning given in formula A2, L.sup.23, L.sup.24, L.sup.25 and L.sup.26 each, independently of one another, are H or F, and X.sup.0 is preferably F.

(275) Very particularly preferred compounds of formula A2 are selected from the group consisting of the following subformulae:

(276) ##STR00116## ##STR00117##
in which R.sup.21 and X.sup.0 are as defined in formula A2.

(277) Particularly preferred compounds of formula A3 are selected from the group consisting of the following subformulae:

(278) ##STR00118##
in which R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meaning given in formula A3, and X.sup.0 is preferably F.

(279) Particularly preferred compounds of formula A4 are selected from the group consisting of the following subformulae:

(280) ##STR00119##
in which R.sup.21 is as defined in formula A4.

(281) Preferably component B) of the LC medium comprises one or more compounds of formula B selected from the group consisting of the following formulae:

(282) ##STR00120##

(283) in which g, A.sup.31, A.sup.32, R.sup.31, X.sup.0, L.sup.31 and L.sup.32 have the meanings given in formula B, and X.sup.0 is preferably F. Particularly preferred are compounds of formulae B1 and B2.

(284) Particularly preferred compounds of formula B1 are selected from the group consisting of the following subformulae:

(285) ##STR00121##
in which R.sup.31, X.sup.0, L.sup.31 and L.sup.32 have the meaning given in formula B1, and X.sup.0 is preferably F.

(286) Very particularly preferred compounds of formula B1a are selected from the group consisting of the following subformulae:

(287) ##STR00122##
in which R.sup.31 is as defined in formula B1.

(288) Very particularly preferred compounds of formula B1b are selected from the group consisting of the following subformulae:

(289) ##STR00123##
in which R.sup.31 is as defined in formula B1.

(290) Particularly preferred compounds of formula B2 are selected from the group consisting of the following subformulae:

(291) ##STR00124## ##STR00125##
in which R.sup.31, X.sup.0, L.sup.31 and L.sup.32 have the meaning given in formula B2, L.sup.33, L.sup.34, L.sup.35 and L.sup.36 are each, independently of one another, H or F, and X.sup.0 is preferably F.

(292) Very particularly preferred compounds of formula B2 are selected from the group consisting of the following subformulae:

(293) ##STR00126##
in which R.sup.31 is as defined in formula B2.

(294) Very particularly preferred compounds of formula B2b are selected from the group consisting of the following subformulae

(295) ##STR00127##
in which R.sup.31 is as defined in formula B2.

(296) Very particularly preferred compounds of formula B2c are selected from the group consisting of the following subformulae:

(297) ##STR00128##
in which R.sup.31 is as defined in formula B2.

(298) Very particularly preferred compounds of formula B2d and B2e are selected from the group consisting of the following subformulae:

(299) ##STR00129##
in which R.sup.31 is as defined in formula B2.

(300) Very particularly preferred compounds of formula B2f are selected from the group consisting of the following subformulae:

(301) ##STR00130##
in which R.sup.31 is as defined in formula B2.
Very particularly preferred compounds of formula B2g are selected from the group consisting of the following subformulae:

(302) ##STR00131##

(303) in which R.sup.31 is as defined in formula B2.

(304) Very particularly preferred compounds of formula B2h are selected from the group consisting of the following subformulae:

(305) ##STR00132##
in which R.sup.31 is as defined in formula B2.

(306) Very particularly preferred compounds of formula B2i are selected from the group consisting of the following subformulae:

(307) ##STR00133##
in which R.sup.31 is as defined in formula B2.

(308) Very particularly preferred compounds of formula B2k are selected from the group consisting of the following subformulae:

(309) ##STR00134##
in which R.sup.31 is as defined in formula B2.

(310) Very particularly preferred compounds of formula B21 are selected from the group consisting of the following subformulae:

(311) ##STR00135##
in which R.sup.31 is as defined in formula B2.

(312) Alternatively to, or in addition to, the compounds of formula B1 and/or B2 component B) of the LC medium may also comprise one or more compounds of formula B3 as defined above.

(313) Particularly preferred compounds of formula B3 are selected from the group consisting of the following subformulae:

(314) ##STR00136##
in which R.sup.31 is as defined in formula B3.

(315) Preferably component B) of the LC medium comprises, in addition to the compounds of formula A and/or B, one or more compounds of formula C

(316) ##STR00137##
in which the individual radicals have the following meanings:

(317) ##STR00138##
each, independently of one another, and on each occurrence, identically or differently

(318) ##STR00139## R.sup.41, R.sup.42 each, independently of one another, alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated, Z.sup.41, Z.sup.42 each, independently of one another, —CH.sub.2CH.sub.2—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH.sub.2O—, —CF.sub.2O—, —C═C— or a single bond, preferably a single bond, h 0, 1, 2 or 3.

(319) In the compounds of formula C, R.sup.41 and R.sup.42 are preferably selected from straight-chain alkyl or alkoxy with 1, 2, 3, 4, 5 or 6 C atoms, and straight-chain alkenyl with 2, 3, 4, 5, 6 or 7 C atoms.

(320) In the compounds of formula C, h is preferably 0, 1 or 2.

(321) In the compounds of formula C, Z.sup.41 and Z.sup.42 are preferably selected from COO, trans-CH═CH and a single bond, very preferably from COO and a single bond.

(322) Preferred compounds of formula C are selected from the group consisting of the following subformulae:

(323) ##STR00140## ##STR00141##
wherein R.sup.41 and R.sup.42 have the meanings given in formula C, and preferably denote each, independently of one another, alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy with 1 to 7 C atoms, or alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl with 2 to 7 C atoms.

(324) Further preferably component B) of the LC medium comprises, in addition to the compounds of formula A and/or B, one or more compounds of formula D

(325) ##STR00142##
in which A.sup.41, A.sup.42, Z.sup.41, Z.sup.42, R.sup.41, R.sup.42 and h have the meanings given in formula C or one of the preferred meanings given above.

(326) Preferred compounds of formula D are selected from the group consisting of the following subformulae:

(327) ##STR00143##
in which R.sup.41 and R.sup.42 have the meanings given in formula D and R.sup.41 preferably denotes alkyl bedeutet, and in formula D1 R.sup.42 preferably denotes alkenyl, particularly preferably —(CH.sub.2).sub.2—CH═CH—CH.sub.3, and in formula D2 R.sup.42 preferably denotes alkyl, —(CH.sub.2).sub.2—CH═CH.sub.2 or —(CH.sub.2).sub.2—CH═CH—CH.sub.3.

(328) Further preferably component B) of the LC medium comprises, in addition to the compounds of formula A and/or B, one or more compounds of formula E containing an alkenyl group

(329) ##STR00144##
in which the individual radicals, on each occurrence identically or differently, each, independently of one another, have the following meaning:

(330) ##STR00145## R.sup.A1 alkenyl having 2 to 9 C atoms or, if at least one of the rings X, Y and Z denotes cyclohexenyl, also one of the meanings of R.sup.A2, R.sup.A2 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—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, x 1 ort.

(331) R.sup.A2 is preferably straight-chain alkyl or alkoxy having 1 to 8 C atoms or straight-chain alkenyl having 2 to 7 C atoms.

(332) Preferred compounds of formula E are selected from the following subformulae:

(333) ##STR00146##
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 2-7 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—.

(334) Very preferred compounds of the formula E are selected from the following sub-formulae:

(335) ##STR00147##
in which m denotes 1, 2, 3, 4, 5 or 6, i denotes 0, 1, 2 or 3, and R.sup.b1 denotes H, CH.sub.3 or C.sub.2H.sub.5.

(336) Very particularly preferred compounds of the formula E are selected from the following sub-formulae:

(337) ##STR00148##

(338) Most preferred are compounds of formula E1a2, E1a5, E3a1 and E6a1.

(339) Further preferably component B) of the LC medium comprises, in addition to the compounds of formula A and/or B, one or more compounds of formula F

(340) ##STR00149##
in which the individual radicals have, independently of each other and on each occurrence identically or differently, the following meanings:

(341) ##STR00150##
denote

(342) ##STR00151## R.sup.21, R.sup.31 each, independently of one another, alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated, X.sup.0 F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, Z.sup.21 —CH.sub.2CH.sub.2—, —CF.sub.2CF.sub.2—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH.sub.2O— or a single bond, preferably —CH.sub.2CH.sub.2—, —COO—, trans-CH═CH— or a single bond, particularly preferably —COO—, trans-CH═CH— or a single bond, L.sup.21, L.sup.22, L.sup.23, L.sup.24 each, independently of one another, H or F, g 0, 1, 2 or 3.

(343) Particularly preferred compounds of formula F are selected from the group consisting of the following formulae:

(344) ##STR00152##
in which R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meaning given in formula F, L.sup.25 and L.sup.26 are each, independently of one another, H or F, and X.sup.0 is preferably F.

(345) Very particularly preferred compounds of formula F1-F3 are selected from the group consisting of the following subformulae:

(346) ##STR00153##

(347) In which R.sup.21 is as defined in formula F1.

(348) The concentration of the compounds of formula A and B in the LC host mixture is preferably from 2 to 60%, very preferably from 3 to 45%, most preferably from 4 to 35%.

(349) The concentration of the compounds of formula C and D in the LC host mixture is preferably from 2 to 70%, very preferably from 5 to 65%, most preferably from 10 to 60%.

(350) The concentration of the compounds of formula E in the LC host mixture is preferably from 5 to 50%, very preferably from 5 to 35%.

(351) The concentration of the compounds of formula F in the LC host mixture is preferably from 2 to 30%, very preferably from 5 to 20%.

(352) Further preferred embodiments of this second preferred embodiment of the present invention are listed below, including any combination thereof. 2a) The LC host mixture comprises one or more compounds of formula A and/or B with high positive dielectric anisotropy, preferably with Δε>15. 2b) The LC host mixture comprises one or more compounds selected from the group consisting of formulae A1a2, A1b1, A1d1, A1f1, A2a1, A2h1, A2l2, A2k1, B2h3, B2l1, F1a. The proportion of these compounds in the LC host mixture is preferably from 4 to 40%, very preferably from 5 to 35%. 2c) The LC host mixture comprises one or more compounds selected from the group consisting of formulae B2c1, B2c4, B2f4, C14. The proportion of these compounds in the LC host mixture is preferably from 4 to 40%, very preferably from 5 to 35%. 2d) The LC host mixture comprises one or more compounds selected from the group consisting of formulae C3, C4, C5, C9 and D2. The proportion of these compounds in the LC host mixture is preferably from 8 to 70%, very preferably from 10 to 60%. 2e) The LC host mixture comprises one or more compounds selected from the group consisting of formulae G1, G2 and G5, preferably G1a, G2a and G5a. The proportion of these compounds in the LC host mixture is preferably from 4 to 40%, very preferably from 5 to 35%. 2f) The LC host mixture comprises one or more compounds selected from the group consisting of formulae E1, E3 and E6, preferably E1a, E3a and E6a, very preferably E1a2, E1a5, E3a1 and E6a1. The proportion of these compounds in the LC host mixture is preferably from 5 to 60%, very preferably from 10 to 50%.

(353) The combination of compounds of the preferred embodiments mentioned above with the polymerised compounds described above causes low threshold voltages, low rotational viscosities and very good low-temperature stabilities in the LC media according to the invention at the same time as constantly high clearing points and high HR values, and allows the rapid establishment of a particularly low pretilt angle in PSA displays. In particular, the LC media exhibit significantly shortened response times, in particular also the grey-shade response times, in PSA displays compared with the media from the prior art.

(354) The LC media and LC host mixtures of the present invention preferably have a nematic phase range of at least 80 K, particularly preferably at least 100 K, and a rotational viscosity ≤250 mPa.Math.s, preferably ≤200 mPa.Math.s, at 20° C.

(355) In the VA-type displays according to the invention, the molecules in the layer of the LC medium in the switched-off state are aligned perpendicular to the electrode surfaces (homeotropically) or have a a tilted homeotropic alignment. On application of an electrical voltage to the electrodes, a realignment of the LC molecules takes place with the longitudinal molecular axes parallel to the electrode surfaces.

(356) LC media according to the invention based on compounds with negative dielectric anisotropy according to the first preferred embodiment, in particular for use in displays of the PS-VA, PS-UB-FFS and SA-VA type, have a negative dielectric anisotropy Δε, preferably from −0.5 to −10, in particular from −2.5 to −7.5, at 20° C. and 1 kHz.

(357) The birefringence Δn in LC media according to the invention for use in displays of the PS-VA, PS-UB-FFS and SA-VA type is preferably below 0.16, particularly preferably from 0.06 to 0.14, very particularly preferably from 0.07 to 0.12.

(358) In the OCB-type displays according to the invention, the molecules in the layer of the LC medium have a “bend” alignment. On application of an electrical voltage, a realignment of the LC molecules takes place with the longitudinal molecular axes perpendicular to the electrode surfaces.

(359) LC media according to the invention, based on compounds with positive dielectric anisotropy according to the second preferred embodiment, for use in displays of the PS-TN-, PS-posi-VA-, PS-IPS-, PS-FFS and SA-FFS type, preferably have a positive dielectric anisotropy Δε from +2 to +30, particularly preferably from +3 to +20, at 20° C. and 1 kHz.

(360) The birefringence Δn in LC media according to the invention for use in displays of the PS-OCB type is preferably from 0.14 to 0.22, particularly preferably from 0.16 to 0.22.

(361) The birefringence Δn in LC media according to the invention for use in displays of the PS-TN-, PS-posi-VA-, PS-IPS-, PS-FFS and SA-FFS type is preferably from 0.07 to 0.15, particularly preferably from 0.08 to 0.13.

(362) The LC media according to the invention may also comprise further additives which are known to the person skilled in the art and are described in the literature, such as, for example, polymerisation initiators, inhibitors, stabilisers, surface-active substances or chiral dopants. These may be polymerisable or non-polymerisable. Polymerisable additives are accordingly ascribed to the polymerisable component or component A). Non-polymerisable additives are accordingly ascribed to the non-polymerisable component or component B).

(363) In a preferred embodiment the LC media contain one or more chiral dopants, preferably in a concentration from 0.01 to 1%, very preferably from 0.05 to 0.5%. The chiral dopants are preferably selected from the group consisting of compounds from Table B below, very preferably from the group consisting of R- or S-1011, R- or S-2011, R- or S-3011, R- or S-4011, and R- or S-5011.

(364) In another preferred embodiment the LC media contain a racemate of one or more chiral dopants, which are preferably selected from the chiral dopants mentioned in the previous paragraph.

(365) In another preferred embodiment the LC medium according to the present invention contains a self-aligning (SA) additive, preferably in a concentration of 0.1 to 2.5%. An LC medium according to this preferred embodiment is especially suitable for use in polymer stabilised SA-VA and SA-FFS displays.

(366) In a preferred embodiment the SA-VA or SA-FFS display according to the present invention does not contain a polyimide alignment layer. In another preferred embodiment the SA-VA or SA-FFS display according to preferred embodiment contains a polyimide alignment layer.

(367) Preferred SA additives for use in this preferred embodiment are selected from compounds comprising a mesogenic group and a straight-chain or branched alkyl side chain that is terminated with one or more polar anchor groups selected from hydroxy, carboxy, amino or thiol groups.

(368) Further preferred SA additives contain one or more polymerisable groups which are attached, optionally via spacer groups, to the mesogenic group. These polymerisable SA additives can be polymerised in the LC medium under similar conditions as applied for the RMs in the PSA process.

(369) Suitable SA additives to induce homeotropic alignment, especially for use in SA-VA mode displays, are disclosed for example in US 2013/0182202 A1, US 2014/0838581 A1, US 2015/0166890 A1 and US 2015/0252265 A1.

(370) In another preferred embodiment an LC medium or a polymer stabilised SA-VA or SA-FFS display according to the present invention contains one or more self-aligning additives selected from Table E below.

(371) Furthermore, it is possible to add to the LC media, for example, 0 to 15% by weight of pleochroic dyes, furthermore nanoparticles, conductive salts, preferably ethyldimethyldodecylammonium 4-hexoxybenzoate, tetrabutylammonium tetraphenylborate or complex salts of crown ethers (cf., for example, Haller et al., Mol. Cryst. Liq. Cryst. 24, 249-258 (1973)), for improving the conductivity, or substances for modifying the dielectric anisotropy, the viscosity and/or the alignment of the nematic phases. Substances of this type are described, for example, in DE-A 22 09 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 28 53 728.

(372) The individual components of the preferred embodiments a)-z) of the LC media according to the invention are either known or methods for the preparation thereof can readily be derived from the prior art by the person skilled in the relevant art, since they are based on standard methods described in the literature. Corresponding compounds of the formula CY are described, for example, in EP-A-0 364 538. Corresponding compounds of the formula ZK are described, for example, in DE-A-26 36 684 and DE-A-33 21 373.

(373) The LC media which can be used in accordance with the invention are prepared in a manner conventional per se, for example by mixing one or more of the above-mentioned compounds with one or more polymerisable compounds as defined above, and optionally with further liquid-crystalline compounds and/or additives. In general, the desired amount of the components used in lesser amount is dissolved in the components making up the principal constituent, advantageously at elevated temperature. It is also possible to mix solutions of the components in an organic solvent, for example in acetone, chloroform or methanol, and to remove the solvent again, for example by distillation, after thorough mixing. The invention furthermore relates to the process for the preparation of the LC media according to the invention.

(374) It goes without saying to the person skilled in the art that the LC media according to the invention may also comprise compounds in which, for example, H, N, O, Cl, F have been replaced by the corresponding isotopes like deuterium etc.

(375) The following examples explain the present invention without restricting it. However, they show the person skilled in the art preferred mixture concepts with compounds preferably to be employed and the respective concentrations thereof and combinations thereof with one another. In addition, the examples illustrate which properties and property combinations are accessible.

(376) Preferred mixture components are shown in Tables A1 and A2 below. The compounds shown in Table A1 are especially suitable for use in LC mixtures with positive dielectric anisotropy. The compounds shown in Table A2 are especially suitable for use in LC mixtures with negative dielectric anisotropy.

(377) TABLE-US-00001 TABLE A1 In Table A1, m and n are independently of each other an integer from 1 to 12, preferably 1, 2, 3, 4, 5 or 6, k is 0, 1, 2, 3, 4, 5 or 6, and (O)C.sub.mH.sub.2m+1 means C.sub.mH.sub.2m+1 or OC.sub.mH.sub.2m+1. APU-n-OXF ACQU-n-F APUQU-n-F BCH-nF.F BCH-nF.F.F BCH-n.Fm 0 CFU-n-F CBC-nm CBC-nmF CCOC-n-m C-n-V C-n-XF C-n-m CC-n-V CC-n-Vm CC-n-kVm 0 CC-nV-Vm CCP-nV-m CCP-Vn-m CCG-V-F CCVC-n-V CCP-n-m CP-nV-m CP-Vn-m CPPC-nV-Vm CVCP-1V-OT 0 CLP-n-T CLP-n-OT CLP-nV-T CLP-nV-OT CLP-Vn-T CLP-Vn-OT CLP-nVm-T CLP-nVm-OT CLP-nVk-m CPGP-n-m 0 CCP-nOCF.sub.3 CCP-nF.F.F CGG-n-F CGU-n-F CDU-n-F DCU-n-F CCGU-n-F CPGU-n-F CCPU-n-F CPGU-n-OT 00 CCQU-n-F 01 CCQG-n-F 02 CUQU-n-F 03 CQU-n-F 04 CCCQU-n-F 05 CDUQU-n-F 06 CLUQU-n-F 07 CPPQU-n-F 08 CGUQU-n-F 09 CCZU-n-F 0 CGZP-n-OT CPTU-n-F GPTU-n-F CPU-n-VT CPU-n-AT CPU-n-OXF CWCG-n-F CWCU-n-F CWCQU-n-F Dec-U-n-F 0 LPP-n-m DPGU-n-F DPGU-n-OT DGUQU-n-F DUUQU-n-F ECCP-nm ECCP-nOCF.sub.3 GP-n-Cl GGP-n-Cl GGP-n-F 0 PGIGI-n-F GPQU-n-F GUQGU-n-F PGU-n-OXF MPP-n-F MUQU-n-F NUQU-n-F PGU-n-F PPGU-n-F PQU-n-F 0 PUQU-n-F PGUQU-n-F PGP-n-m PGP-n-kVm PP-nV-Vm PP-n-kVm PCH-nOm PCH-nCl PYP-nF

(378) TABLE-US-00002 TABLE A2 In Table A2, m and n are independently of each other an integer from 1 to 12, preferably 1, 2, 3, 4, 5 or 6, k is 0, 1, 2, 3, 4, 5 or 6, and (O)C.sub.mH.sub.2m+1 means C.sub.mH.sub.2m+1 or OC.sub.mH.sub.2m+1. 0 0 0 0 0 00 01 02 03 04 05 06 07 08 09 0 0 0 0 0 0 0

(379) In a first preferred embodiment of the present invention, the LC media according to the invention, especially those with positive dielectric anisotropy, comprise one or more compounds selected from the group consisting of compounds from Table A1.

(380) In a second preferred embodiment of the present invention, the LC media according to the invention, especially those with negative dielectric anisotropy, comprise one or more compounds selected from the group consisting of compounds from Table A2.

(381) TABLE-US-00003 TABLE B Table B shows possible chiral dopants which can be added to the LC media according to the invention. 0 0

(382) The LC media preferably comprise 0 to 10% by weight, in particular 0.01 to 5% by weight, particularly preferably 0.1 to 3% by weight, of dopants. The LC media preferably comprise one or more dopants selected from the group consisting of compounds from Table B.

(383) TABLE-US-00004 TABLE C Table C shows possible stabilisers which can be added to the LC media according to the invention. Therein n denotes an integer from 1 to 12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, and terminal methyl groups are not shown. 00 01 02 03 04 05 06 07 08 09 0 0 0 0

(384) 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. The LC media preferably comprise one or more stabilisers selected from the group consisting of compounds from Table C.

(385) TABLE-US-00005 TABLE D Table D shows illustrative reactive mesogenic compounds which can be used in the LC media in accordance with the present invention. RM-1 RM-2 RM-3 RM-4 RM-5 RM-6 RM-7 RM-8 RM-9 0 RM-10 RM-11 RM-12 RM-13 RM-14 RM-15 RM-16 RM-17 RM-18 RM-19 0 RM-20 RM-21 RM-22 RM-23 RM-24 RM-25 RM-26 RM-27 RM-28 RM-29 0 RM-30 RM-31 RM-32 RM-33 RM-34 RM-35 RM-36 RM-37 RM-38 RM-39 0 RM-40 RM-41 RM-42 RM-43 RM-44 RM-45 RM-46 RM-47 RM-48 RM-49 0 RM-50 RM-51 RM-52 RM-53 RM-54 RM-55 RM-56 RM-57 RM-58 RM-59 00 RM-60 01 RM-61 02 RM 62 03 RM-63 04 RM-64 05 RM-65 06 RM-66 07 RM-67 08 RM-68 09 RM-69 0 RM-70 RM-71 RM-72 RM-73 RM-74 RM-75 RM-76 RM-77 RM-78 RM-79 0 RM-80 RM-81 RM-82 RM-83 RM-84 RM-85 RM-86 RM-87 RM-88 RM-89 0 RM-90 RM-91 RM-92 RM-93 RM-94 RM-95 RM-96 RM-97 RM-98 RM-99 0 RM-100 RM-101 RM-102 RM-103 RM-104 RM-105 RM-106 RM-107 RM-108 RM-109 0 RM-110 RM-111 RM-112 RM-113 RM-114 RM-115 RM-116 RM-117 RM-118 RM-119 0 RM-120 RM-121 RM-122 RM-123 RM-124 RM-125 RM-126 RM-127 RM-128 RM-129 0 RM-130 RM-131 RM-132 RM-133 RM-134 RM-135 RM-136 RM-137 RM-138 RM-139 0 RM-140 RM-141 RM-142 RM-143

(386) In a preferred embodiment, the mixtures according to the invention comprise one or more polymerisable compounds, preferably selected from the polymerisable compounds of the formulae RM-1 to RM-140. Of these, compounds RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM40, RM-41, RM-48, RM-52, RM-54, RM-57, RM-64, RM-74, RM-76, RM-88, RM-102, RM-103, RM-109, RM-117, RM-120, RM-121 and RM-122 are particularly preferred.

(387) TABLE-US-00006 TABLE E Table E shows self-alignment additives for vertical alignment which can be used in LC media for SA-VA and SA-FFS displays according to the present invention together with the polymerizable compounds of formula I: SA-1 SA-2 SA-3 SA-4 SA-5 SA-6 0 SA-7 SA-8 SA-9 SA-10 SA-11 SA-12 SA-13 SA-14 SA-15 SA-16 00 SA-17 01 SA-18 02 SA-19 03 SA-20 04 SA-21 05 SA-22 06 SA-23 07 SA-24 08 SA-25 09 SA-26 0 SA-27 SA-28 SA-29 SA-30 SA-31 SA-32 SA-33 SA-34

(388) In a preferred embodiment, the LC media, SA-VA and SA-FFS displays according to the present invention comprise one or more SA additives selected from formulae SA-1 to SA-34, preferably from formulae SA-14 to SA-34, very preferably from formulae SA-20 to SA-28, most preferably of formula SA-20, in combination with one or more RMs of formula I. Very preferred is a combination of polymerizable compound 1, 2 or 3 of Example 1 below, very preferably of polymerizable compound 3 of Example 1, with an SA additive of formula SA-20 to SA-28, very preferably of formula SA-20.

EXAMPLES

(389) The following examples explain the present invention without restricting it. However, they show the person skilled in the art preferred mixture concepts with compounds preferably to be employed and the respective concentrations thereof and combinations thereof with one another. In addition, the examples illustrate which properties and property combinations are accessible.

(390) In addition, the following abbreviations and symbols are used: V.sub.0 threshold voltage, capacitive [V] at 20° C., n.sub.e extraordinary refractive index at 20° C. and 589 nm, n.sub.o ordinary refractive index at 20° C. and 589 nm, Δn optical anisotropy at 20° C. and 589 nm, ε.sub.⊥ dielectric permittivity perpendicular to the director at 20° C. and 1 kHz, ε.sub.∥ dielectric permittivity parallel to the director at 20° C. and 1 kHz, Δε dielectric anisotropy at 20° C. and 1 kHz, cl.p., T(N,I) clearing point [° C.], γ.sub.1 rotational viscosity at 20° C. [mPa.Math.s], K.sub.1 elastic constant, “splay” deformation at 20° C. [pN], K.sub.2 elastic constant, “twist” deformation at 20° C. [pN], K.sub.3 elastic constant, “bend” deformation at 20° C. [pN].

(391) Unless explicitly noted otherwise, all concentrations in the present application are quoted in percent by weight and relate to the corresponding mixture as a whole, comprising all solid or liquid-crystalline components, without solvents.

(392) Unless explicitly noted otherwise, all temperature values indicated in the present application, such as, for example, for the melting point T(C,N), the transition from the smectic (S) to the nematic (N) phase T(S,N) and the clearing point T(N,I), are quoted in degrees Celsius (° C.). M.p. denotes melting point, cl.p.=clearing point. Furthermore, C=crystalline state, N=nematic phase, S=smectic phase and I=isotropic phase. The data between these symbols represent the transition temperatures.

(393) All physical properties are and have been determined in accordance with “Merck Liquid Crystals, Physical Properties of Liquid Crystals”, Status November 1997, Merck KGaA, Germany, and apply for a temperature of 20° C., and Δn is determined at 589 nm and Δε at 1 kHz, unless explicitly indicated otherwise in each case.

(394) The term “threshold voltage” for the present invention relates to the capacitive threshold (V.sub.0), also known as the Freedericks threshold, unless explicitly indicated otherwise. In the examples, the optical threshold may also, as generally usual, be quoted for 10% relative contrast (V.sub.10).

(395) Unless stated otherwise, the process of polymerising the polymerisable compounds in the PSA displays as described above and below is carried out at a temperature where the LC medium exhibits a liquid crystal phase, preferably a nematic phase, and most preferably is carried out at room temperature.

(396) Unless stated otherwise, methods of preparing test cells and measuring their electrooptical and other properties are carried out by the methods as described hereinafter or in analogy thereto.

(397) The display used for measurement of the capacitive threshold voltage consists of two plane-parallel glass outer plates at a separation of 25 μm, each of which has on the inside an electrode layer and an unrubbed polyimide alignment layer on top, which effect a homeotropic edge alignment of the liquid-crystal molecules.

(398) The display or test cell used for measurement of the tilt angles consists of two plane-parallel glass outer plates at a separation of 4 μm, each of which has on the inside an electrode layer and a polyimide alignment layer on top, where the two polyimide layers are rubbed antiparallel to one another and effect a homeotropic edge alignment of the liquid-crystal molecules.

(399) The polymerisable compounds are polymerised in the display or test cell by irradiation with UV light of defined intensity for a prespecified time, with a voltage simultaneously being applied to the display (usually 10 V to 30 V alternating current, 1 kHz). In the examples, unless indicated otherwise, a metal halide lamp and an intensity of 100 mW/cm.sup.2 is used for polymerisation.

(400) The intensity is measured using a standard meter (Hoenle UV-meter high end with UV sensor).

(401) The tilt angle is determined using the Mueller Matrix Polarimeter “AxoScan” from Axometrics. A low value (i.e. a large deviation from the 90° angle) corresponds to a large tilt here.

(402) Unless stated otherwise, the term “tilt angle” means the angle between the LC director and the substrate, and “LC director” means in a layer of LC molecules with uniform orientation the preferred orientation direction of the optical main axis of the LC molecules, which corresponds, in case of calamitic, uniaxially positive birefringent LC molecules, to their molecular long axis.

Example 1: Polymerisable Compounds

(403) Polymerisable compound (or “RM”) 1 is prepared as follows

(404) ##STR00618##

(405) 1.4: A suspension of sodium hydride (5.4 g, 60% in mineral oil, 135.6 mmol) was added to a stirred solution of benzyl alcohol 1.3 (20.0 g, 113.0 mmol) in THF (20 mL) at 0° C. The resulting mixture was stirred for 10 min at the same temperature before it was treated with methyl iodide (8.7 mL, 135.6 mmol). The reaction mixture was stirred for 4 hours at ambient temperature, carefully quenched with water and extracted with ethyl acetate. Aqueous phase was separated and extracted with ethyl acetate (2 times). The combined organic phase was washed with sat. NaCl solution, dried over Na.sub.2SO.sub.4, filtered and concentrated in vacuo. The residue was purified with flash chromatography (heptane) to give 1.4 as a colorless oil. (21.0 g, 97%; GC: 99.9%).

(406) ##STR00619##

(407) 1.6: Hydrazine hydrate (0.2 mL, 80%, 0.004 mol) was added to a stirred solution of sodium metaborate tetrahydrate (43.3 g, 0.314 mol) and PdCl.sub.2[P(cy).sub.3].sub.2 (3.1 g, 0.004 mol) in THF (5 mL)/water (60 mL) at room temperature. The resulting mixture was stirred for 5 min at ambient temperature before it was treated with a solution of 1.4 (20.0 g, 0.105 mol) and 1.5 (74.9 g, 0.199 mol) in THF (520 mL). The reaction mixture was stirred overnight at 70° C., phases separated and the aqueous phase was extracted with methyl tert-butyl ether (2 times). The combined organics were washed with water, dried over Na.sub.2SO.sub.4, filtered and concentrated in vacuo. The residue (67.0 g, 103%) was used in the next step without further purification.

(408) ##STR00620##

(409) 1.7: A solution of TBAF (in THF, 1.0 M, 158 mL, 158 mmol) was added dropwise to a stirred solution of 1.6 (42.0 g, 67.8 mmol) in THF (500 mL) at 5° C. The resulting mixture was stirred 30 min at 3° C., followed by 1 h at ambient temperature, before it was poured on 40 mL ice, acidified with HCl (2.0 M) until pH=6 and extracted with ethyl acetate (3 times). The combined organic phase was washed with sat. NaCl solution, dried over Na.sub.2SO.sub.4, filtered and concentrated in vacuo. The residue was purified with flash chromatography (dichloromethane/methanol) to give 1.7 as white crystals (9.6 g, 46%).

(410) ##STR00621##

(411) 1: Methacrylic acid (6.7 g, 78.3 mmol) and 4-dimethylaminopyridine (DMAP, 0.38 g, 3.1 mmol) were added to a stirred solution of biphenol 1.7 (9.6 g, 31.1 mmol) in dichloromethane (150 mL) at room temperature. The resulting mixture was cooled to 3° C. followed by dropwise addition 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (12.2 g, 78.3 mmol) in dichloromethane (20 mL). The reaction mixture was allowed to warm to room temperature and stirred overnight, before it was concentrated in vacuo. The residue was purified by flash chromatography (heptane/ethyl acetate) and recrystallized from heptane/ethanol (2:1) to give 1 as white crystals (10.2 g, 74%; HPLC: 99.7%). .sup.1H NMR (CDCl.sub.3): 2.12-2.13 (m, 6H), 3.41 (s, 3H), 4.43 (s, 2H), 5.80-5.82 (m, 2H), 6.41-6.42 (m, 2H), 7.27-7.21 (m, 4H), 7.40 (d, J=7.9 Hz, 1H), 7.45-7.49 (m, 2H), 7.60 (dd, J=7.9, 2.0 Hz, 1H), 7.74-7.65 (m, 2H), 7.78 (d, J=1.9 Hz, 1H); EI-MS: 442.0.

(412) DSC: Tg 0 K 117 I.

(413) In analogy to polymerizable compound 1, the following compounds have been synthesized:

(414) ##STR00622##

(415) 2: Melting Point: 117° C. .sup.1H NMR (CDCl.sub.3): δ 7.76 (d, J=2.3 Hz, 1H), 7.72-7.66 (m, 6H), 7.62 (dd, J=8.3, 2.4 Hz, 1H), 7.27-7.22 (m, 3H), 6.42 (dt, J=8.0, 1.2 Hz, 2H), 5.82 (dp, J=7.9, 1.6 Hz, 2H), 4.51 (s, 2H), 3.43 (s, 3H), 2.13 (t, J=1.2 Hz, 3H), 2.12 (t, J=1.3 Hz, 3H). EI-MS: 442.2

(416) ##STR00623##

(417) 3: Melting Point: 74° C. .sup.1H NMR (CDCl.sub.3): δ 7.69 (d, J=2.3 Hz, 1H), 7.65-7.61 (m, 2H), 7.55 (dd, J=8.3, 2.4 Hz, 1H), 7.26-7.19 (m, 3H), 6.41 (dt, J=8.3, 1.2 Hz, 2H), 5.81 (dt, J=8.3, 1.6 Hz, 2H), 4.49 (s, 2H), 3.42 (s, 3H), 2.12 (t, J=1.3 Hz, 3H), 2.11 (t, J=1.2 Hz, 3H). EI-MS: 366.0

Example 2: Polymerisable Mixtures

(418) The nematic LC host mixture N1 is formulated as follows:

(419) TABLE-US-00007 CCH-501  9.00% cl.p. 70.0° C. CCH-35 14.00% Δn   0.0825 PCH-53  8.00% Δε −3.5 CY-3-O4 14.00% ε.sub.∥   3.5 CY-5-O4 13.00% K.sub.3/K.sub.1   1.00 CCY-2-1  9.00% γ.sub.1 .sup.  141 mPa s CCY-3-1  9.00% V.sub.0 .sup. 2.10 V CCY-3-O2  8.00% CCY-5-O2  8.00% CPY-2-O2  8.00%

(420) The nematic LC host mixture N2 is formulated as follows:

(421) TABLE-US-00008 CY-3-O2 18.00% cl.p. +74.5° C. CPY-2-O2 10.00% Δn   0.1021 CPY-3-O2 10.00% Δε −3.1 CCY-3-O2  9.00% ε.sub.∥   3.5 CCY-4-O2  4.00% K.sub.3/K.sub.1   1.16 PYP-2-3  9.00% γ.sub.1 .sup.     86 m Pa s CC-3-V 40.00% V.sub.0   .sup. 2.29 V

(422) The nematic LC host mixture N3 is formulated as follows:

(423) TABLE-US-00009 CC-3-V1  9.00% cl.p. CCH-23 14.00% Δn CCH-34  6.00% Δε CCH-35  6.00% ε.sub.∥ CCP-3-1  7.00% K.sub.3/K.sub.1 CCY-3-O1  5.00% γ.sub.1 CCY-3-O2 10.00% V.sub.0 CPY-3-O2 12.00% CY-3-O2  9.50% PP-1-2V1  8.50% PY-3-O2 12.00% PY-4-O2  1.00%

(424) Polymerisable mixtures P11, P21 and P31 according to the present invention are prepared by adding polymerisable compound RM1 of Example 1 to nematic LC host mixture N1, N2 or N3, respectively.

(425) For comparison purpose, polymerisable mixtures C11, C12, C21, C22, C31 and C32 are prepared by adding RM C1 which has a biphenyl core and no substituent, or RM C2 which has a terphenyl core and a fluorine substituent, to nematic LC host mixture N1, N2 or N3, respectively.

(426) ##STR00624##

(427) The concentrations of the RMs in the polymerisable mixtures are selected such that the molar amount is in each case 0.093 mmol per 10 g mixture. The compositions of the individual polymerisable mixtures are shown in Table 1.

(428) TABLE-US-00010 TABLE 1 Polymerisable mixture composition Mix. No. C11 C12 P11 C21 C22 P21 LC Host N1 N1 N1 N2 N2 N2 RM C1 C2 1 C1 C2 1 wt. % RM 0.300 0.427 0.412 0.300 0.427 0.412 Mix. No. C31 C32 P31 LC Host N3 N3 N3 RM C1 C2 1 wt. % RM 0.300 0.427 0.412 wt. % RM — 0.400 0.386 (tilt stability)

Example 3: Use Examples

(429) The individual polymerisable mixtures are filled into PSA test cells, the RM is polymerised under application of a voltage, and several properties like residual RM content, VHR under UV stress, tilt angle generation and tilt angle stability are measured.

(430) Residual RM Measurement

(431) The polymerisation speed is measured by determining the residual content of residual, unpolymerised RM (in % by weight) in the mixture after UV exposure with a given intensity and lamp spectrum after a given UV exposure time. The smaller the residual RM content after a given time interval, the faster the polymerization,

(432) For this purpose the polymerisable mixtures are filled into electrooptic test cells made of soda lime glass coated with an approximately 200 nm thick layer of ITO and a 30 nm layer of VA-polyimide from Varitronix with a cell gap of 6-7 μm

(433) The test cells are illuminated by a MH-lamp (UV-Cube 2000) using a 320 nm long pass filter (N-WG320) and a light intensity of 100 mW/cm.sup.2, causing polymerisation of the RM. Illumination times are given in the tables below.

(434) After polymerization the test cells are opened, and the mixture is dissolved and rinsed out of the test cell with 2 ml ethyl methyl ketone and analyzed by High Performance Liquid Chromatography (HPLC). For better comparison, the results are given by % relative to the initial RM amount. Thus, at 0 min illumination time 100% of RM are still present, while after x min illumination time y % of the RM are still present. The results are shown in Table 2.

(435) TABLE-US-00011 TABLE 2 Residual RM content Mixture UV Time/min 0 2 4 6 C11 residual RM/%.sub.rel 100 80 63 53 C12 100 41 19 10 P11 100 67 42 22 Mixture UV Time/min 0 2 6 C21 residual RM/%.sub.rel 100 49 19 C22 100 24 2 P21 100 40 8

(436) From Table 2 it can be seen that, for polymerisable mixtures with RM1 according to the invention, the residual RM amount is significantly lower and polymerisation is significantly faster compared to polymerisable mixtures with biphenyl RM C.sub.1, whereas residual RM amount is only slightly higher and polymerisation slightly slower compared to polymerisable mixtures with fluorinated terphenyl RM C.sub.2.

(437) Voltage Holding Ratio (VHR)

(438) For measuring the VHR the polymerisable mixtures are filled into electrooptic test cells which consist of two AF glass substrates with an approximately 20 nm thick ITO layer and a 100 nm thick polyimide layer.

(439) The VHR is measured at 100° C. with application of a voltage of 1 V/60 Hz before and after illumination. The sun-test consists of 2 h illumination by a Xenon lamp type Atlas Suntest CPS+ with a light intensity of 765 W/m.sup.2 at 20° C. The UV test consists of 10 min illumination by a metal halide lamp (UV cube 2000) using a 320 nm long pass filter (N-WG320) and a light intensity of 100 mW/cm.sup.2 at 20° C.

(440) The difference in VHR between the different RMs, based on RM 01 is expressed according to:
ΔVHR=VHR.sub.RM−VHR.sub.RM-C1

(441) A positive value corresponds to an improvement in VHR with respect to the reference RM C1, a negative value represents a decrease in VHR with respect to the reference.

(442) The results are shown in Table 3.

(443) TABLE-US-00012 TABLE 3 VHR values Δ VHR (%) Mixture no illumination 2 h Suntest C11 0 0 C12 0 −2 P11 0 0 Δ VHR (%) Mixture no illumination 2 h Suntest 10 min UV C21 0 0 0 C22 0 −4 −2 P21 0 0 0

(444) From Table 3 it can be seen that RM1 according to the invention is able to maintain the VHR level of the reference RM C1, and is able to provide higher VHR stability than fluorinated terphenyl RM C2.

(445) Tilt Angle Generation

(446) For measuring the tilt angle generation the polymerisable mixtures are filled into electrooptic test cells made of two soda-lime glass substrates coated with an ITO electrode layer of approx. 200 nm thickness and a VA-polyimide alignment layer (JALS-2096-R1) of approx. 30 nm thickness which is rubbed antiparallel. The cell gap is approx. 4 μm.

(447) The test cells are illuminated by a MH-lamp (UV-Cube 2000) using a 320 nm long pass filter (N-WG320) and a light intensity of 100 mW/cm.sup.2 at 20° C. with an applied square voltage of 24 V.sub.RMS (alternating current, 1 khz), causing polymerisation of the RM and a generation of a tilt angle. Illumination times are given in the respective tables. The generated tilt was measured after a period of time of 12 hours using the Mueller Matrix Polarimeter “AxoScan” from Axometrics. The results are shown in Table 4.

(448) TABLE-US-00013 TABLE 4 Tilt angle Mixture UV Time/min  0  2  6 C11 Tilt/° 90 85 78 C12 88 76 71 P11 88 79 71 Mixture UV Time/min  0  2  6 C21 Tilt/° 89 77 70 C22 89 82 79 P21 90 77 73

(449) From Table 4 it can be seen that, in LC host N1 with RM1 according to the invention, the tilt angle generation does initially proceed faster but remains at a higher angle compared to LC host N1 with biphenyl RM C1, but is similar to LC host N1 with fluorinated terphenyl RM C2.

(450) In LC host N2 with RM1 according to the invention, the tilt angle generation does initially proceed faster but remains at a higher angle compared to LC host N1 with fluorinated terphenyl RM C2, but is similar to LC host N1 with biphenyl RM C1.

(451) Tilt Stability

(452) For the tilt stability measurements the RMs C2 and RM1 are used in concentrations corresponding to 0.087 mmol per 10 g of host mixture N3, as shown in Table 1 above.

(453) The mixtures are filled into test cells made of soda lime glass coated with a 200 nm layer of ITO and a 30 nm layer of poly imide (JALS-2096-R1) were used. The polyimide layers are rubbed anti parallel to each other. Cellgap is approx. 4 μm.

(454) The tilt is generated via illumination by a metal halide lamp (UV-Cube 2000) using a 320 nm long pass filter (N-WG320) and a light intensity of 100 mW/cm.sup.2 at 20° C. with an applied square voltage of 10 V.sub.RMS (1 khz). The generated tilt is measured after a period of time of 12 hours using the Mueller Matrix Polarimeter “AxoScan” from Axometrics.

(455) For RM C2 a pre-tilt of 84.8° was generated in N3 and for RM1 a tilt angle of 87.5° was generated in N3. Then the cells were electrically stressed with a square wave of 10 V.sub.RMS at 1 khz frequency for 168 h at 40° C. After a relaxation time of 10-20 min the tilt angles were measured again. The results are shown below in Table 5 according to the following equation:
tilt.sub.after stress−tilt.sub.after tilt generation=Δ−tilt

(456) The closer this value gets to 0, the more stable is the generated tilt. A high tilt stability is also an indicator for reduced image sticking in the display.

(457) TABLE-US-00014 TABLE 5 Tilt Stability Mixture Δ Tilt/° P31 0.3 C32 0.5

(458) From Table 5 it can be seen that the generated tilt is more stable in case of RM1 compared to fluorinated terphenyl RM C2.

(459) Overall the above results demonstrate that the RMs according to the present invention enable a fast UV-curing with complete polymerisation while maintaining a low ion content and high VHR in the mixture after UV-processing, and enable fast and strong tilt angle generation with high tilt stability after electrical stress.

(460) Thus, the RMs according to the present invention combines very fast polymerisation speed similar to that terphenyl RMs with reliability parameters similar to biphenyl RMs, and thus show a superior overall performance compared to RMs of prior art.