Liquid-crystal medium

Abstract

Disclosed are a liquid crystal (LC) medium containing a polymerisable compound, a process for its preparation, its use for optical, electro-optical and electronic purposes, in particular in LC displays, especially in an LC display of the polymer sustained alignment (PSA) type, and to an LC display, especially a PSA display.

Claims

1. A liquid crystal (LC) medium comprising one or more polymerisable compounds, one or more compounds of formula A, one or more compounds of formula B, and one or more compounds of formula T ##STR00360## in which R.sup.1, R.sup.2 are, each independently, an 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, and L.sup.1, L.sup.2, L.sup.3 are, each independently, F or Cl.

2. The LC medium of claim 1, wherein the one or more compounds of formula A are of the following formula: ##STR00361## wherein alkyl denotes a straight-chain alkyl radical having 1-6 C atoms, and (O) denotes an oxygen atom or a single bond.

3. The LC medium of claim 1, wherein the one or more compounds of formula B1 are of the following formula: ##STR00362## wherein alkyl denotes a straight-chain alkyl radical having 1-6 C atoms, and (O) denotes an oxygen atom or a single bond.

4. The LC medium according to claim 1, wherein the one or more compounds of formula T are of formula T1 ##STR00363## wherein alkyl denotes a straight-chain alkyl radical having 1-6 C atoms, and (O) denotes an oxygen atom or a single bond.

5. The LC medium according to claim 1, wherein the one or more polymerisable compounds are of formula I
R.sup.a—B.sup.1—(Z.sup.b—B.sup.2).sub.m—R.sup.b  I in which R.sup.a and R.sup.b are, each independently, P, P-Sp-, H, F, Cl, Br, I, —CN, —NO.sub.2, —NCO, —NCS, —OCN, —SCN, SF.sub.5 or a straight-chain or branched alkyl having 1 to 25 C atoms, in which one or more non-adjacent CH.sub.2 groups are each optionally replaced, independently of one another, by —C(R.sup.0)═C(R.sup.00)—, —C≡C—,—N(R.sup.00)—, —O—, —S—, —CO—, —CO—O—, —O—CO—, or —O—CO—O— in such a way that O and/or S atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by F, Cl, Br, I, CN, P or P-Sp-, wherein, if B.sup.1 and/or B.sup.2 contain a saturated C atom, R.sup.a and/or R.sup.b also denote a radical which is spiro-linked to said saturated C atom, wherein at least one of the radicals R.sup.a and R.sup.b denotes or contains a group P or P-Sp-, P is a polymerisable group, Sp is a spacer group or a single bond, B.sup.1 and B.sup.2 are, each independently, an aromatic, heteroaromatic, alicyclic or heterocyclic group, which optionally contains fused rings, and which is unsubstituted, or mono- or polysubstituted by L, Zb is —O—, —S—, —CO—, —CO—O—, —OCO—, —O—CO—O—, —OCH.sub.2—, —CH.sub.2O—, —SCH.sub.2—, —CH.sub.2S—, —CF.sub.2O—, —OCF.sub.2—, —CF.sub.2S—, —SCF.sub.2—, —(CH.sub.2).sub.n1—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —(CF.sub.2).sub.n1—, —CH═CH—, —CF═CF—, —C ≡C—, —CH═CH—COO—, —OCO—CH═CH—, CR.sup.0R.sup.00 or a single bond, R.sup.0 and R.sup.00 are, each independently, H or alkyl having 1 to 12 C atoms, m is 0, 1, 2, 3 or 4, n.sup.1 is 1, 2, 3 or 4, L is P, P-Sp-, OH, CH.sub.2OH, 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, optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, in which one or more H atoms are optionally replaced by F, CL, P or P-Sp-, Y.sup.1 is halogen, and R.sup.x is P, P-Sp-, H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, in which one or more non-adjacent CH.sub.2 groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, or —O—CO—O— in such a way that O and/or S atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by F, Cl, P or P-Sp-, an optionally substituted aryl or aryloxy group having 6 to 40 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 40 C atoms.

6. The LC medium according to claim 5, wherein B.sup.1 and B.sup.2 each, independently of one another, are 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl, naphthalene-2,6-diyl, phenanthrene-2,7-diyl, 9,10-dihydro -phenanthrene-2,7-diyl, anthracene-2,7-diyl, fluorene-2,7-diyl, coumarine, flavone, where one or more CH groups in these groups are optionally replaced by N, cyclohexane-1,4-diyl, in which one or more non-adjacent CH.sub.2 groups are optionally replaced by O and/or S, 1,4-cyclohexenylene, bicycle[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, piperidine—1,4-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4—tetrahydronaphthalene-2,6-diyl, indane-2,5-diyl or octahydro-4,7-methanoindane-2,5-diyl, where all these groups are optionally unsubstituted or mono- or polysubstituted by L.

7. The LC medium according to claim 1, wherein the one or more polymerisable compounds are of the following formulae: ##STR00364## ##STR00365## ##STR00366## ##STR00367## ##STR00368## in which P.sup.1, P.sup.2, P.sup.3 are, each independently, a vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane or epoxy group, Sp.sup.1, Sp.sup.2, Sp.sup.3 are, each independently, a single bond or a spacer group, where 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-optionally also 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 is H, F, Cl, CN or a straight-chain or branched alkyl having 1 to 25 C atoms, in which one or more non-adjacent CH.sub.2 groups are optionally each replaced, independently of one another, by —C(R )═C(R.sup.00)—, —C≡C—, —N(R.sup.0)—, —O—, —S—, —CO—, —CO—O—, —O—CO—, or —O—CO—O— in such a way that O and/or S atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by F, Cl, CN or P.sup.1-Sp.sup.1-, R.sub.0, R.sup.00 are, each independently, H or alkyl having 1 to 12 C atoms, R.sup.y and R.sup.z are, each independently, H, F, CH.sub.3 or CF.sub.3, X.sup.1, X.sup.2, X.sup.3 are, each independently, —CO—O—, —O—CO— or a single bond, Z.sup.1 are, each independently, —O—, —CO—, —C(R.sup.yR.sup.z)— or —CF.sub.2CF.sub.2—, Z.sup.2, Z.sup.3 are, each independently, —CO—O—, —O—CO—, —CH.sub.2O—, —OCH.sub.2—, —CF.sub.2O—, —OCF.sub.2— or (CH.sub.2).sub.n—, N is 2, 3 or 4, L is F, Cl, CN or a straight-chain or branched, optionally mono- or poly-fluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, L′, L″ are, each independently, H, F or Cl, r is 0, 1, 2, 3 or 4, s is 0, 1, 2 or 3, t is 0, 1 or 2, and x is 0 or 1.

8. The LC medium according to claim 7, wherein the one or more polymerisable compounds are of formulae M2 and M13.

9. The LC medium according to claim 1, comprising a polymerisable component A) comprising one or more polymerisable compounds, and an LC component B) comprising one or more compounds of formula A , one or more compounds of formula B, one or more compounds of formula T, and optionally one or more additional mesogenic or liquid-crystalline compounds.

10. The LC medium according to claim 1, comprising one or more compounds of formulae AN and AY: ##STR00369## in which ##STR00370## 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 one or two non-adjacent CH.sub.2 groups are optionally 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 are, each independently, H, F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F or CHF.sub.2H, x is 1 or 2, and z is 0 or 1.

11. The LC medium according to claim 1, comprising one or more compounds of formulae CY and PY: ##STR00371## in which a denotes 1 or 2, b denotes 0 or 1, ##STR00372## R.sup.1 and R.sup.2 each, independently of one another, denote alkyl having 1 to 12 C atoms, where one or two non-adjacent CH.sub.2 groups are optionally 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.xdenotes —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, and L.sup.1-4 each, independently of one another, denote F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F, or CHF.sub.2.

12. The LC medium according to claim 1, comprising one or more compounds of formulae ZK and DK: ##STR00373## in which ##STR00374## R.sup.3 and R.sup.4 each, independently of one another, denote alkyl having 1 to 12 C atoms, in which one or two non-adjacent CH.sub.2 groups are optionally 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.ydenotes —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, R.sup.5 and R.sup.6 each, independently of one another, denote alkyl having 1 to 12 C atoms, where one or two non-adjacent CH.sub.2 groups are optionally replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, and E denotes 1 or 2.

13. The LC medium according to claim 1, wherein the polymerisable compounds are polymerised.

14. An LC display comprising an LC medium according to claim 1.

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

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

17. The LC display of claim 15, 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 the LC medium, wherein the polymerisable compounds are polymerised between the substrates of the display.

18. A process for the production of an LC display according to claim 17, comprising providing the LC medium between the substrates of the display, and polymerising the polymerisable compounds.

19. A process of preparing an LC medium according to claim 1, comprising mixing together one or more compounds of formula A, one or more compounds of formula B, one or more compounds of formula T, with one or more polymerisable compounds, and optionally with further LC compounds and/or additives.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Unless stated otherwise, the polymerisable compounds are preferably selected from achiral compounds.

(2) 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.

(3) 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.

(4) 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”.

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

(6) 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”.

(7) 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.

(8) 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.

(9) 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.

(10) Above and below,

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

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

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

(14) “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.

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

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

(17) ##STR00004##

(18) 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.

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

(20) 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.

(21) 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.

(22) 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 alkyldienyl, 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.

(23) 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.

(24) 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,

(25) 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.

(26) 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—

(27) 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.

(28) Preferred alkyl groups are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, cyclo-pentyl, 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.

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

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

(31) Preferred alkoxy groups are, for example, methoxy, ethoxy, 2-methoxy-ethoxy, 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.

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

(33) 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.

(34) 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.

(35) 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.

(36) 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, benzo-pyridazine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, aza-carbazole, benzocarboline, phenanthridine, phenanthroline, thieno[2,3b]-thiophene, thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene, dibenzothiophene, benzothiadiazothiophene, or combinations of these groups.

(37) 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.

(38) 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.

(39) 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—.

(40) 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.

(41) 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.

(42) Preferred substituents, hereinafter also referred to as “L”, are 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,

(43) 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

(44) Y.sup.1 denotes halogen.

(45) “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.

(46) Particularly preferred substituents L 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.

(47) ##STR00005##
is preferably

(48) ##STR00006##
in which L has one of the meanings indicated above.

(49) 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.

(50) 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—,

(51) ##STR00007##
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.

(52) 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—,

(53) ##STR00008##
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 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, 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.

(54) 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—,

(55) ##STR00009##

(56) 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.

(57) If 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 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—CO—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—CO—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.

(58) 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.

(59) Typical spacer groups Sp and -Sp″-X″— are, for example, —(CH.sub.2).sub.p1—, —(CH.sub.2CH.sub.2O).sub.q1—CH.sub.2CH.sub.2—, —CH.sub.2CH.sub.2—S—CH.sub.2CH.sub.2—, —CH.sub.2CH.sub.2—NH—CH.sub.2CH.sub.2— or —(SiR.sup.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.

(60) 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—CO—O—, in which p1 and q1 have the meanings indicated above.

(61) 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-methylimino-ethylene, 1-methylalkylene, ethenylene, propenylene and butenylene.

(62) Preferred compounds of formula A are selected of formula A1:

(63) ##STR00010##
wherein alkyl denotes a straight-chain alkyl radical having 1-6 C atoms, and (O) denotes an oxygen atom or a single bond. Very preferred are compounds of formula A1 wherein (O) denotes an oxygen atom and alkyl is methyl, ethyl, propyl, butyl of pentyl or hexyl, which are preferably straight-chained.

(64) Preferably the proportion of compounds of formula A or A1 in the LC medium is from 2 to 35%, very preferably from 3 to 30%, most preferably from 5 to 25%.

(65) Preferably the LC medium contains 1 to 5, preferably 1, 2 or 3 compounds of formula A or A1.

(66) The compounds of formula B are preferably selected of formula B1

(67) ##STR00011##
wherein alkyl denotes a straight-chain alkyl radical having 1-6 C atoms, and (O) denotes an oxygen atom or a single bond. Very preferred are compounds of formula B1 wherein both groups (O) denote an oxygen atom and alkyl is methyl, ethyl, propyl, butyl of pentyl or hexyl, which are preferably straight-chained.

(68) Preferably the proportion of compounds of formula B or B1 in the LC medium is from 0.5 to 20%, very preferably from 1 to 15%, most preferably from 1 to 10%.

(69) Preferably the LC medium contains 1 to 5, preferably 1, 2 or 3 compounds of formula B or B1.

(70) The compounds of formula T are preferably selected of formula T1

(71) ##STR00012##
wherein alkyl denotes a straight-chain alkyl radical having 1-6 C atoms, and (O) denotes an oxygen atom or a single bond. Very preferred are compounds of formula T1 wherein (O) denotes an oxygen atom and alkyl is methyl, ethyl, propyl, butyl of pentyl or hexyl, which are preferably straight-chained.

(72) Preferably the LC medium contains not more than 5% of compounds of formula T or T1.

(73) Preferably the proportion of compounds of formula T or T1 in the LC medium is from 0.1 to 5%, very preferably from 0.5 to 4%.

(74) Preferably the LC medium contains 1 to 5, preferably 1 or 2 compounds of formula T or T1.

(75) In the LC medium according to the present invention, the use of an LC host mixture comprising compounds of formula A, B and T, but not containing any further terphenyl compounds, together with the use of a polymerisable component comprising preferably direactive and/or trireactive RMs, leads to advantageous properties in PSA displays. In particular, one or more of the following advantages could be achieved: good UV absorption also at longer wavelengths, quick and complete polymerisation of the RMs, quick generation of a low pretilt angle, especially already at low UV energy and/or at longer UV wavelengths, high pretilt angle stability after UV exposure, reduced image sticking, reduced ODF mura, high reliability and high VHR value after UV exposure and/or heat treatment, high birefringence, reduced viscosity faster response times.

(76) Since the LC medium according to the present invention shows high absorption at longer UV wavelengths, it is possible to use longer UV wavelengths for polymerisation, which is advantageous for the display manufacturing process.

(77) The polymerisable compounds are preferably selected from formula I
R.sup.a—B.sup.1—(Z.sup.b—B.sup.2).sub.m—R.sup.b  I
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: R.sup.a and R.sup.b P, P-Sp-, H, F, Cl, Br, I, —CN, —NO.sub.2, —NCO, —NCS, —OCN, —SCN, SF.sub.5 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.00)—, —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, Br, I, CN, P or P-Sp-, where, if B.sup.1 and/or B.sup.2 contain a saturated C atom, R.sup.a and/or R.sup.b may also denote a radical which is spiro-linked to this saturated C atom, wherein at least one of the radicals R.sup.a and R.sup.b denotes or contains a group P or P-Sp-, P a polymerisable group, Sp a spacer group or a single bond, B.sup.1 and B.sup.2 an aromatic, heteroaromatic, alicyclic or heterocyclic group, preferably having 4 to 25 ring atoms, which may also contain fused rings, and which is unsubstituted, or mono- or polysubstituted by L, Z.sup.b —O—, —S—, —CO—, —CO—O—, —OCO—, —O—CO—O—, —OCH.sub.2—, —CH.sub.2O—, —SCH.sub.2—, —CH.sub.2S—, —CF.sub.2O—, —OCF.sub.2—, —CF.sub.2S—, —SCF.sub.2—, —(CH.sub.2).sub.n1—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —(CF.sub.2).sub.n1—, —CH═CH—, —CF═CF—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH—, CR.sup.0R.sup.00 or a single bond, R.sup.0 and R.sup.00 each, independently of one another, denote H or alkyl having 1 to 12 C atoms, m denotes 0, 1, 2, 3 or 4, n1 denotes 1, 2, 3 or 4, L P, P-Sp-, OH, CH.sub.2OH, 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, optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, in which, in addition, one or more H atoms may be replaced by F, Cl, P or P-Sp-, P and Sp have the meanings indicated above, Y.sup.1 denotes halogen, R.sup.x denotes P, P-Sp-, H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 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, Cl, P or P-Sp-, an optionally substituted aryl or aryloxy group having 6 to 40 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 40 C atoms.

(78) Particularly preferred compounds of the formula I are those in which B.sup.1 and B.sup.2 each, independently of one another, denote 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl, naphthalene-2,6-diyl, phenanthrene-2,7-diyl, 9,10-dihydro-phenanthrene-2,7-diyl, anthracene-2,7-diyl, fluorene-2,7-diyl, coumarine, flavone, where, in addition, one or more CH groups in these groups may be replaced by N, cyclohexane-1,4-diyl, in which, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by 0 and/or S, 1,4-cyclohexenylene, bicycle[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane -1,4-diyl, spiro[3.3]heptane-2,6-diyl, piperidine-1,4-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, indane-2,5-diyl or octahydro-4,7-methanoindane-2,5-diyl, where all these groups may be unsubstituted or mono- or polysubstituted by L as defined above.

(79) Particularly preferred compounds of the formula I are those in which B.sup.1 and B.sup.2 each, independently of one another, denote 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl,

(80) Very preferred compounds of formula I are selected from the following formulae:

(81) ##STR00013## ##STR00014## ##STR00015## ##STR00016## ##STR00017##
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: P.sup.1, P.sup.2, P.sup.3 a vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane or epoxy group, Sp.sup.1, Sp.sup.2, Sp.sup.3 a single bond or a spacer group 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 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 H or alkyl having 1 to 12 C atoms, R.sup.y and R.sup.z H, F, CH.sub.3 or CF.sub.3, X.sup.1, X.sup.2, X.sup.3 —CO—O—, —O—CO— or a single bond, Z.sup.1 —O—, —CO—, —C(R.sup.yR.sup.z)— or —CF.sub.2CF.sub.2—, Z.sup.2, Z.sup.3 —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 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, L′, L″ H, F or Cl, r 0, 1, 2, 3 or 4, s 0, 1, 2 or 3, t 0, 1 or 2, x 0 or 1.

(82) Especially preferred are compounds of formulae M2 and M13.

(83) Further preferred are trireactive compounds M15 to M30, in particular M17, M18, M19, M22, M23, M24, M25, M29 and M30.

(84) In the compounds of formulae M1 to M30 the group

(85) ##STR00018##
is preferably

(86) ##STR00019##
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 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.

(87) Preferred compounds of formulae M1 to M30 are those wherein P.sup.1, P.sup.2 and P.sup.3 denote an acrylate, methacrylate, oxetane or epoxy group, very preferably an acrylate or methacrylate group.

(88) Further preferred compounds of formulae M1 to M30 are those wherein Sp.sup.1, Sp.sup.2 and Sp.sup.3 are a single bond.

(89) Further preferred compounds of formulae M1 to M30 are those wherein one of Sp.sup.1, Sp.sup.2 and Sp.sup.3 is a single bond and another one of Sp.sup.1, Sp.sup.2 and Sp.sup.3 is different from a single bond.

(90) Further preferred compounds of formulae M1 to M30 are those wherein those groups Sp.sup.1, Sp.sup.2 and Sp.sup.3 that are different from a single bond denote —(CH.sub.2).sub.s1—X″—, wherein s1 is an integer from 1 to 6, preferably 2, 3, 4 or 5, and X″ is X″ is the linkage to the benzene ring and is —O—, —O—CO—, —CO—O, —O—CO—O— or a single bond.

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

(92) Preferably the proportion of compounds of formula I in the LC medium is from 0.01 to 5%, very preferably from 0.05 to 1%, most preferably from 0.1 to 0.5%.

(93) It was observed that, the combination of polymerisable compounds of formulae M1 to M30 with the compounds of formula A, B and T leads to advantageous behaviour of the LC medium, where a quick and complete polymerisation, the quick generation of a low pretilt angle which is stable after UV exposure, at the same time a high reliability and high VHR value after UV exposure can be achieved together with a high birefringence.

(94) Besides, the LC medium shows high absorption at longer UV wavelengths, so that it is possible to use such longer UV wavelengths for polymerisation, which is advantageous for the display manufacturing process.

(95) 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.

(96) 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.

(97) 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.

(98) 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.

(99) 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.

(100) 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.

(101) 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.

(102) 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.

(103) 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”).

(104) 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.

(105) 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.

(106) 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.

(107) 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.

(108) 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.

(109) 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.

(110) 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.

(111) 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.

(112) “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.

(113) 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.

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

(115) Preferably the LC medium according to the present invention does essentially consist of a polymerisable component A) 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.

(116) Preference is given to LC media in which the polymerisable component A) consists exclusively of polymerisable compounds of formula I*.

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

(118) 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%.

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

(120) 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.

(121) Examples of these compounds are the aforementioned compounds of formulae A, B and T.

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

(123) 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.

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

(125) In a preferred embodiment of the present invention the LC component B), or LC host mixture, of the LC medium comprises, in addition to the compounds of formula A, one or more further mesogenic or LC compounds comprising a straight-chain, branched or cyclic 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.

(126) These further alkenyl compounds are preferably selected from formula AN and AY

(127) ##STR00020##
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning:

(128) ##STR00021## 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.1-4 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.

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

(130) Further preferred compounds of formula AN and AY are those wherein 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, and 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.

(131) The compounds of the formula AN are preferably selected from the following sub-formulae:

(132) ##STR00022## ##STR00023##
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—.

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

(134) ##STR00024##
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.

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

(136) ##STR00025##

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

(138) The compounds of the formula AY are preferably selected from the following sub-formulae:

(139) ##STR00026## ##STR00027## ##STR00028##
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—.

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

(141) ##STR00029##
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—.

(142) The LC medium preferably comprises no compounds containing a terminal vinyloxy group (—O—CH═CH.sub.2), in particular no compounds of the formula AN or AY in which R.sup.A1 or R.sup.A2 denotes or contains a terminal vinyloxy group (—O—CH═CH.sub.2).

(143) 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)-z) below: a) LC medium which comprises one or more compounds of the formulae CY and/or PY:

(144) ##STR00030## wherein a denotes 1 or 2, b denotes 0 or 1,

(145) ##STR00031## 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. 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. The compounds of the formula CY are preferably selected from the group consisting of the following sub-formulae:

(146) ##STR00032## ##STR00033## ##STR00034## ##STR00035## 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—. The compounds of the formula PY are preferably selected from the group consisting of the following sub-formulae:

(147) ##STR00036## ##STR00037## ##STR00038## 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 which additionally comprises one or more compounds of the following formula:

(148) ##STR00039## in which the individual radicals have the following meanings:

(149) ##STR00040## 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. The compounds of the formula ZK are preferably selected from the group consisting of the following sub-formulae:

(150) ##STR00041## 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—. Especially preferred are compounds of formula ZK1. Particularly preferred compounds of formula ZK are selected from the following sub-formulae:

(151) ##STR00042## wherein the propyl, butyl and pentyl groups are straight-chain groups. Most preferred are compounds of formula ZK1a. c) LC medium which additionally comprises one or more compounds of the following formula:

(152) ##STR00043## 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,

(153) ##STR00044##
and e denotes 1 or 2. The compounds of the formula DK are preferably selected from the group consisting of the following sub-formulae:

(154) ##STR00045## ##STR00046## 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—. d) LC medium which additionally comprises one or more compounds of the following formula:

(155) ##STR00047## in which the individual radicals have the following meanings:

(156) ##STR00048## 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. 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. The compounds of the formula LY are preferably selected from the group consisting of the following sub-formulae:

(157) ##STR00049## ##STR00050## ##STR00051## 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—. e) LC medium which additionally comprises one or more compounds selected from the group consisting of the following formulae:

(158) ##STR00052## 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. f) LC medium which additionally comprises one or more compounds selected from the group consisting of the following formulae:

(159) ##STR00053## ##STR00054## 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. g) LC medium which additionally comprises one or more biphenyl compounds selected from the group consisting of the following formulae:

(160) ##STR00055## 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—. The proportion of the biphenyls of the formulae B1 to B3 in the LC mixture is preferably at least 3% by weight, in particular ≧5% by weight. The compounds of the formula B2 are particularly preferred. The compounds of the formulae B1 to B3 are preferably selected from the group consisting of the following sub-formulae:

(161) ##STR00056## 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. h) LC medium which additionally comprises one or more compounds selected from the group consisting of the following formulae:

(162) ##STR00057## 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. Preferred media comprise one or more compounds selected from the formulae O1, O3 and O4. i) LC medium which additionally comprises one or more compounds of the following formula:

(163) ##STR00058## in which

(164) ##STR00059## 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. Particularly preferred compounds of the formula FI are selected from the group consisting of the following sub-formulae:

(165) ##STR00060## 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. k) LC medium which additionally comprises one or more compounds selected from the group consisting of the following formulae:

(166) ##STR00061## in which R.sup.8 has the meaning indicated for R.sup.1, and alkyl denotes a straight-chain alkyl radical having 1-6 C atoms. l) LC medium which additionally comprises one or more compounds which contain a tetrahydronaphthyl or naphthyl unit, such as, for example, the compounds selected from the group consisting of the following formulae:

(167) ##STR00062## ##STR00063## 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. m) LC medium which additionally comprises one or more difluorodibenzo-chromans and/or chromans of the following formulae:

(168) ##STR00064## 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. Particularly preferred compounds of the formulae BC, CR and RC are selected from the group consisting of the following sub-formulae:

(169) ##STR00065## ##STR00066## ##STR00067## 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—. Very particular preference is given to mixtures comprising one, two or three compounds of the formula BC-2. n) LC medium which additionally comprises one or more fluorinated phenanthrenes and/or dibenzofurans of the following formulae:

(170) ##STR00068## 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. Particularly preferred compounds of the formulae PH and BF are selected from the group consisting of the following sub-formulae:

(171) ##STR00069## in which R and R′ each, independently of one another, denote a straight-chain alkyl or alkoxy radical having 1-7 C atoms. o) LC medium which additionally comprises one or more monocyclic compounds of the following formula

(172) ##STR00070## 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. 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, The compounds of the formula Y are preferably selected from the group consisting of the following sub-formulae:

(173) ##STR00071## 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—. Particularly preferred compounds of the formula Y are selected from the group consisting of the following sub-formulae:

(174) ##STR00072## wherein Alkoxy preferably denotes straight-chain alkoxy with 3, 4, or 5 C atoms. p) LC medium which, apart from the polymerisable compounds according to the invention, in particular of the formula I or sub-formulae thereof and the comonomers, comprises no compounds which contain a terminal vinyloxy group (—O—CH═CH.sub.2). q) LC medium which comprises 1 to 5, preferably 1, 2 or 3, polymerisable compounds, preferably selected from polymerisable compounds according to the invention, in particular of the formula I or sub-formulae thereof. r) LC medium in which the proportion of polymerisable compounds, in particular of the formula I or sub-formulae thereof, in the mixture as a whole is 0.05 to 5%, preferably 0.1 to 1%. s) LC medium which comprises 1 to 8, preferably 1 to 5, compounds of the formulae CY1, CY2, PY1 and/or PY2. The proportion of these compounds in the mixture as a whole is preferably 5 to 60%, particularly preferably 10 to 35%. The content of these individual compounds is preferably in each case 2 to 20%. t) LC medium which comprises 1 to 8, preferably 1 to 5, compounds of the formulae CY9, CY10, PY9 and/or PY10. The proportion of these compounds in the mixture as a whole is preferably 5 to 60%, particularly preferably 10 to 35%. The content of these individual compounds is preferably in each case 2 to 20%. u) LC medium which comprises 1 to 10, preferably 1 to 8, compounds of the formula ZK, in particular compounds of the formulae ZK1, ZK2 and/or ZK6. The proportion of these compounds in the mixture as a whole is preferably 3 to 25%, particularly preferably 5 to 45%. The content of these individual compounds is preferably in each case 2 to 20%. v) LC medium in which the proportion of compounds of the formulae CY, PY and ZK in the mixture as a whole is greater than 70%, preferably greater than 80%. w) LC medium in which the LC host mixture contains one or more compounds containing an alkenyl group, preferably selected from the group consisting of formula CY, PY and LY, wherein one or both of R.sup.1 and R.sup.2 denote straight-chain alkenyl having 2-6 C atoms, formula ZK and DK, wherein one or both of R.sup.3 and R.sup.4 or one or both of R.sup.5 and R.sup.6 denote straight-chain alkenyl having 2-6 C atoms, and formula B2 and B3, very preferably selected from formulae CY15, CY16, CY24, CY32, PY15, PY16, ZK3, ZK4, DK3, DK6, B2 and B3. The concentration of these compounds in the LC host mixture is preferably from 2 to 70%, very preferably from 3 to 55%. x) LC medium which contains one or more, preferably 1 to 5, compounds selected of formula PY1-PY8, very preferably of formula PY2. The proportion of these compounds in the mixture as a whole is preferably 1 to 30%, particularly preferably 2 to 20%. The content of these individual compounds is preferably in each case 1 to 20%.

(175) 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.

(176) Particularly preferred is an LC medium of this second preferred embodiment, which contains one or more compounds selected from the group consisting of compounds of formula AA and BB

(177) ##STR00073##
and optionally contains, in addition to the compounds of formula AA and/or BB, one or more compounds of formula CC

(178) ##STR00074##
in which the individual radicals have the following meanings:

(179) ##STR00075##
each, independently of one another, and on each occurrence, identically or differently

(180) ##STR00076##
each, independently of one another, and on each occurrence, identically or differently

(181) ##STR00077## R.sup.21, R.sup.31, 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, 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, Z.sup.41, Z.sup.42 —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, L.sup.21, L.sup.22, L.sup.31, L.sup.32 H or F, g 0, 1, 2 or 3, h 0, 1, 2 or 3.

(182) 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

(183) The compounds of formula AA are preferably selected from the group consisting of the following formulae:

(184) ##STR00078##
in which A.sup.21, R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meanings given in formula AA, 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 AA1 and AA2.

(185) Particularly preferred compounds of formula AA1 are selected from the group consisting of the following subformulae:

(186) ##STR00079##
in which R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meaning given in formula AA1, 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.

(187) Very particularly preferred compounds of formula AA1 are selected from the group consisting of the following subformulae:

(188) ##STR00080##

(189) In which R.sup.21 is as defined in formula AA1.

(190) Very preferred compounds of formula AA2 are selected from the group consisting of the following subformulae:

(191) ##STR00081## ##STR00082##
in which R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meaning given in formula AA2, 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.

(192) Very particularly preferred compounds of formula AA2 are selected from the group consisting of the following subformulae:

(193) ##STR00083## ##STR00084##
in which R.sup.21 and X.sup.0 are as defined in formula AA2.

(194) Particularly preferred compounds of formula AA3 are selected from the group consisting of the following subformulae:

(195) ##STR00085##
in which R.sup.21, X.sup.0, L.sup.21 and L.sup.22 have the meaning given in formula AA3, and X.sup.0 is preferably F.

(196) Particularly preferred compounds of formula AA4 are selected from the group consisting of the following subformulae:

(197) ##STR00086##
in which R.sup.21 is as defined in formula AA4.

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

(199) ##STR00087##
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 BB, and X.sup.0 is preferably F. Particularly preferred are compounds of formulae BB1 and BB2.

(200) Particularly preferred compounds of formula BB1 are selected from the group consisting of the following subformulae:

(201) ##STR00088##
in which R.sup.31, X.sup.0, L.sup.31 and L.sup.32 have the meaning given in formula BB1, and X.sup.0 is preferably F.

(202) Very particularly preferred compounds of formula BB1a are selected from the group consisting of the following subformulae:

(203) ##STR00089##
in which R.sup.31 is as defined in formula BB1.

(204) Very particularly preferred compounds of formula BB1 b are selected from the group consisting of the following subformulae:

(205) ##STR00090##
in which R.sup.31 is as defined in formula BB1.

(206) Particularly preferred compounds of formula BB2 are selected from the group consisting of the following subformulae:

(207) ##STR00091## ##STR00092##
in which R.sup.31, X.sup.0, L.sup.31 and L.sup.32 have the meaning given in formula BB2, 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.

(208) Very particularly preferred compounds of formula BB2 are selected from the group consisting of the following subformulae:

(209) ##STR00093##
in which R.sup.31 is as defined in formula BB2.

(210) Very particularly preferred compounds of formula BB2b are selected from the group consisting of the following subformulae

(211) ##STR00094##
in which R.sup.31 is as defined in formula BB2.

(212) Very particularly preferred compounds of formula BB2c are selected from the group consisting of the following subformulae:

(213) ##STR00095##
in which R.sup.31 is as defined in formula BB2.

(214) Very particularly preferred compounds of formula BB2d and BB2e are selected from the group consisting of the following subformulae:

(215) ##STR00096##
in which R.sup.31 is as defined in formula BB2.

(216) Very particularly preferred compounds of formula BB2f are selected from the group consisting of the following subformulae:

(217) ##STR00097##
in which R.sup.31 is as defined in formula BB2.

(218) Very particularly preferred compounds of formula BB2g are selected from the group consisting of the following subformulae:

(219) ##STR00098##
in which R.sup.31 is as defined in formula BB2.

(220) Very particularly preferred compounds of formula BB2h are selected from the group consisting of the following subformulae:

(221) ##STR00099##
in which R.sup.31 and X.sup.0 are as defined in formula BB2.

(222) Very particularly preferred compounds of formula BB2i are selected from the group consisting of the following subformulae:

(223) ##STR00100##
in which R.sup.31 and X.sup.0 are as defined in formula BB2.

(224) Very particularly preferred compounds of formula BB2k are selected from the group consisting of the following subformulae:

(225) ##STR00101##
in which R.sup.31 and X.sup.0 are as defined in formula BB2.

(226) Alternatively to, or in addition to, the compounds of formula BB1 and/or BB2 the LC media may also comprise one or more compounds of formula BB3 as defined above.

(227) Particularly preferred compounds of formula BB3 are selected from the group consisting of the following subformulae:

(228) ##STR00102##
in which R.sup.31 is as defined in formula BB3.

(229) Preferably the LC media according to this second preferred embodiment comprise, in addition to the compounds of formula AA and/or BB, one or more dielectrically neutral compounds having a dielectric anisotropy in the range from −1.5 to +3, preferably selected from the group of compounds of formula CC as defined above.

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

(231) ##STR00103## ##STR00104##

(232) In which R.sup.41 and R.sup.42 have the meanings given in formula CC, 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, and L.sup.4 is H or F.

(233) Preferably the LC media according to this second preferred embodiment comprise, in addition or alternatively to the dielectrically neutral compounds of formula CC, one or more dielectrically neutral compounds having a dielectric anisotropy in the range from −1.5 to +3, selected from the group of compounds of formula DD.

(234) ##STR00105##

(235) 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 CC.

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

(237) ##STR00106##
in which R.sup.41 and R.sup.42 have the meanings given in formula DD and R.sup.41 preferably denotes alkyl bedeutet, and in formula DD1 R.sup.42 preferably denotes alkenyl, particularly preferably —(CH.sub.2).sub.2—CH═CH—CH.sub.3, and in formula DD2 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.

(238) The compounds of formula AA and BB are preferably used in the LC medium according to the invention in a concentration from 2% to 60%, more preferably from 3% to 35%, and very particularly preferably from 4% to 30% in the mixture as a whole.

(239) The compounds of formula CC and DD are preferably used in the LC medium according to the invention in a concentration from 2% to 70%, more preferably from 5% to 65%, even more preferably from 10% to 60%, and very particularly preferably from 10%, preferably 15%, to 55% in the mixture as a whole.

(240) 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.

(241) 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.

(242) 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 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.

(243) 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 and PS-UB-FFS type, have a negative dielectric anisotropy Δ∈, preferably from −0.5 to −10, in particular from −2.5 to −7.5, at 20° C. and 1 kHz.

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

(245) 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.

(246) LC media according to the invention for use in displays of the PS-OCB, PS-TN, PS-IPS, PS-posi-VA and PS-FFS type are preferably those based on compounds with positive dielectric anisotropy according to the second preferred embodiment, and preferably have a positive dielectric anisotropy Δ∈ from +4 to +17 at 20° C. and 1 kHz.

(247) 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.

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

(249) 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-oder PS-FFS-type, preferably have a positive dielectric anisotropy Δ∈ from +2 to +30, particularly preferably from +3 to +20, at 20° C. and 1 kHz.

(250) 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).

(251) 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.

(252) 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.

(253) 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, tetrabutyl-ammonium 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.

(254) 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.

(255) 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.

(256) 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.

(257) 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.

(258) The following abbreviations are used:

(259) (n, m, z: in each case, independently of one another, 1, 2, 3, 4, 5 or 6)

(260) TABLE-US-00001 TABLE A 07 08 09 0 0 0 0 0 0 0 0 0 00 01 02 03 04 05 06 07 08 09 0 0 0

(261) In a preferred embodiment of the present invention, the LC media according to the invention comprise one or more compounds selected from the group consisting of compounds from Table A.

(262) TABLE-US-00002 TABLE B C 15 CB 15 CM 21 R/S-811 0 CM 44 CM 45 CM 47 CN R/S-2011 R/S-3011 R/S-4011 R/S-5011 R/S-1011

(263) Table B shows possible chiral dopants which can be added to the LC media according to the invention.

(264) 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.

(265) TABLE-US-00003 TABLE C 0 0 0 0

(266) Table C shows possible stabilisers which can be added to the LC media according to the invention.

(267) (n here denotes an integer from 1 to 12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, terminal methyl groups are not shown).

(268) 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.

(269) TABLE-US-00004 TABLE D RM-1 RM-2 0 RM-3 RM-4 RM-5 RM-6 RM-7 RM-8 RM-9 RM-10 RM-11 RM-12 00 RM-13 01 RM-14 02 RM-15 03 RM-16 04 RM-17 05 RM-18 06 RM-19 07 RM-20 08 RM-21 09 RM-22 0 RM-23 RM-24 RM-25 RM-26 RM-27 RM-28 RM-29 RM-30 RM-31 RM-32 0 RM-33 RM-34 RM-35 RM-36 RM-37 RM-38 RM-39 RM-40 RM-41 RM-42 0 RM-43 RM-44 RM-45 RM-46 RM-47 RM-48 RM-49 RM-50 RM-51 RM-52 0 RM-53 RM-54 RM-55 RM-56 RM-57 RM-58 RM-59 RM-60 RM-61 RM-62 0 RM-63 RM-64 RM-65 RM-66 RM-67 RM-68 RM-69 RM-70 RM-71

(270) Table D shows illustrative compounds which can be used in the LC media in accordance with the present invention, preferably as reactive mesogenic compounds.

(271) In a preferred embodiment of the present invention, the mesogenic media comprise one or more compounds selected from the group of the compounds from Table D. Very preferably the LC medium comprises a compound selected from formulae RM-1 to RM-32, most preferably RM-1, RM-15 or RM-17, or a compound selected from formulae RM-41 to RM-48, most preferably RM-41.

(272) 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, ∈.sub.⊥ dielectric permittivity perpendicular to the director at 20° C. and 1 kHz, ∈.sub.∥ dielectric permittivity parallel to the director at 20° C. and 1 kHz, Δ∈ 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].

(273) 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.

(274) 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.

(275) 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 Δ∈ at 1 kHz, unless explicitly indicated otherwise in each case.

(276) 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).

(277) 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.

(278) 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.

(279) 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.

(280) 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.

(281) The polymerisable compounds are polymerised in the display or test cell by irradiation with UVA 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 50 mW/cm.sup.2 is used for polymerisation. The intensity is measured using a standard UVA meter (Hoenle UV-meter high end with UVA sensor).

(282) The tilt angle is determined by crystal rotation experiment (Autronic-Melchers TBA-105). A low value (i.e. a large deviation from the 90° angle) corresponds to a large tilt here.

(283) The VHR value is measured as follows: 0.3% of a polymerisable monomeric compound is added to the LC host mixture, and the resultant mixture is introduced into VA-VHR test cells which comprise an unrubbed VA-polyimide alignment layer. The LC-layer thickness d is approx. 6 μm, unless stated otherwise. The VHR value is determined before and after UV exposure at 1 V, 60 Hz, 64 μs pulse (measuring instrument: Autronic-Melchers VHRM-105).

(284) LC Host Mixtures

EXAMPLE 1

(285) The nematic LC host mixture N1 is formulated as follows.

(286) TABLE-US-00005 CC-3-V 35.50% cl.p. 74.7° C. CC-3-V1 10.00% Δn 0.1093 CCP-3-1 2.00% Δε −3.2 CCY-3-O1 2.00% ε.sub.∥ 3.5 CLY-3-O2 9.50% γ.sub.1 84 mPa s CPY-2-O2 10.00% CPY-3-O2 10.50% PY-3-O2 16.50% PGIY-3-O2 1.00% B-2O-O5 3.00%

(287) The mixture contains compound CLY-3-O2 of formula A1, compound B-2O -O5 of formula B1, and 1% of terphenyl compound PGIY-2-O4 of formula T1.

COMPARISON EXAMPLE 1

(288) The nematic LC host mixture C1 is formulated as follows.

(289) TABLE-US-00006 CC-3-V 37.00% cl.p. 75.0° C. CC-3-V1 7.00% Δn 0.1089 CCY-3-O1 5.50% Δε −3.2 CLY-3-O2 10.00% ε.sub.∥ 3.5 CPY-2-O2 9.50% γ.sub.1 87 mPa s CPY-3-O2 11 .00% PY-3-O2 19.00% PGIY-2-O4 1.00%

(290) The mixture contains compound CLY-3-O2 of formula A1 and 1% of terphenyl compound PGIY-2-04 of formula T1, but does not contain a compound of formula B.

EXAMPLE 2

(291) The nematic LC host mixture N2 is formulated as follows.

(292) TABLE-US-00007 CC-3-V 37.00% cl.p. 74.6° C. CC-3-V1 10.00% Δn 0.1094 CCY-3-O1 3.50% Δε −3.2 CLY-3-O2 10.00% ε.sub.∥ 3.6 CPY-2-O2 7.00% γ.sub.1 85 mPa s CPY-3-O2 11.00% PY-3-O2 16.50% PGIY-3-O2 3.00% B-2O-O5 3.00%

(293) The mixture contains compound CLY-3-O2 of formula A1, compound B-2O -O5 of formula B, and 3% of terphenyl compound PGIY-3-O2 of formula T1.

COMPARISON EXAMPLE 2

(294) The nematic LC host mixture C2 is formulated as follows.

(295) TABLE-US-00008 CC-3-V 37.00% cl.p. 74.8° C. CC-3-V1 7.00% Δn 0.1094 CCY-3-O1 5.50% Δε −3.2 CLY-3-O2 10.00% ε.sub.∥ 3.5 CPY-2-O2 8.00% γ.sub.1 88 mPa s CPY-3-O2 10.50% PY-3-O2 18.50% PGIY-3-O2 3.00%

(296) The mixture contains compound CLY-3-O2 of formula A1 and 3% of terphenyl compound PGIY-3-O2 of formula T1, but does not contain a compound of formula B.

COMPARISON EXAMPLE 3

(297) The nematic LC host mixture C3 is formulated as follows.

(298) TABLE-US-00009 CC-3-V 32.50% cl.p. 75.2° C. CC-3-V1 10.00% Δn 0.1087 CCP-3-1 4.50% Δε −3.2 CCY-3-O1 9.00% ε.sub.∥ 3.6 CCY-3-O2 3.00% γ.sub.1 90 mPa s CPY-2-O2 8.00% CPY-3-O2 11.00% PY-3-O2 18.00% PGIY-3-O2 1.00% B-2O-O5 3.00%

(299) The mixture contains compound B-2O-O5 of formula B1 and 1% of terphenyl compound PGIY-3-O2 of formula T1, but does not contain a compound of formula A.

COMPARISON EXAMPLE 4

(300) The nematic LC host mixture C4 is formulated as follows.

(301) TABLE-US-00010 CC-3-V 36.00% cl.p. 74.5° C. CC-3-V1 10.50% Δn 0.1094 CCY-3-O1 2.50% Δε −3.2 CLY-3-O2 10.00% ε.sub.∥ 3.5 CPY-2-O2 10.00% γ.sub.1 85 mPa s CPY-3-O2 11.00% PY-3-O2 16.00% PYP-2-3 1.00% B-2O-O5 3.00%

(302) The mixture contains compound CLY-3-O2 of formula A1 and compound B-2O-O5 of formula B1, but contains a terphenyl compound PYP-2-3 which is different from formula T.

COMPARISON EXAMPLE 5

(303) The nematic LC host mixture C5 is formulated as follows.

(304) TABLE-US-00011 CC-3-V 33.00% cl.p. 75.0° C. CC-3-V1 10.00% Δn 0.1084 CCY-3-O1 9.00% Δε −3.2 CCY-3-O2 7.50% ε.sub.∥ 3.6 CPY-2-O2 5.00% γ.sub.1 90 mPa s CPY-3-O2 10.50% PY-3-O2 18.00% PYP-2-3 1.00% B-2O-O5 3.00% BCH-32 3.00%

(305) The mixture contains compound B-2O-O5 of formula B1, but does not contain a compound of formula A, and contains a terphenyl compound PYP-2-3 which is different from formula T.

(306) Polymerisable Mixtures

(307) Polymerisable mixtures are prepared by adding either reactive mesogen M1 or M2 to each of nematic LC host mixtures N1, N2 and C1 to C5, respectively, at a concentration of 0.4% by weight.

(308) ##STR00359##

(309) The composition of the polymerisable mixtures is shown in Table 1 below.

(310) TABLE-US-00012 TABLE 1 Polymerisable Mixture Composition Mix. No. LC Host RM P11 N1 M1 P12 N1 M2 P21 N2 M1 C11 C1 M1 C12 C1 M2 C21 C2 M1 C31 C3 M1 C41 C4 M1 C51 C5 M1

(311) The viscosities of polymerisable mixtures with M1 are shown in Table 2.

(312) TABLE-US-00013 TABLE 2 Viscosities of Polymerisable Mixtures Mix. No. LC Host RM γ.sub.1 [mPa s] P11 N1 M1 84 P21 N2 M1 85 C11 C1 M1 87 C21 C2 M1 88 C31 C3 M1 90 C41 C4 M1 85 C51 C5 M1 90

(313) It can be seen that the polymerisable mixtures P11 and P21 based on nematic host mixtures N1 and N2 according to the present invention show the lowest viscosities.

(314) Mixture C41, which contains terphenyl compound PYP-2-3 that is different from formula T1, has similar viscosity as mixture P11, but shows inferior polymerisation property as will be shown below.

(315) Use Examples

(316) Each of the polymerisable mixtures according to the invention and the polymerisable comparison mixtures are each inserted into a VA e/o test cell. The test cells comprise a VA-polyimide alignment layer (JALS-2096-R1) which is rubbed antiparallel. The LC-layer thickness d is approx. 4 μm.

(317) For polymerisation of the RMs, unless stated otherwise the test cell is irradiated with UV light using a wide band pass filter (300 nm<λ<400 nm) at 10 J (50 mW/cm.sup.2.Math.240 s) with application of a voltage of 14 Vpp (alternating current).

(318) In order to determine the polymerisation rate, the residual content of unpolymerised RM (in % by weight) in the test cells is measured by HPLC after polymerisation. For this purpose the polymerisable mixture is polymerised in the test cell by exposure to UV light (wavelength >320 nm, energy 30 J, exposure time 600 sec). The mixture is then rinsed out of the test cell using MEK (methyl ethyl ketone) and measured.

(319) The residual concentrations of the RM in the mixture after different exposure times are shown in Tables 3-5.

(320) TABLE-US-00014 TABLE 3 Residual monomer content Residual RM [%] C11 P11 C21 P21 40 min 0.0659 0.0492 0.0338 0.0310 60 min 0.0366 0.0254 0.0161 0.0137 80 min 0.0260 0.0164 0.0078 0.0075

(321) From Table 3 it can be seen that the polymerisable mixtures P11 (with 1% terphenyl) and P12 (with 3% terphenyl) according to the present invention show faster polymerisation with lower amount of residual RM, compared to the corresponding polymerisable mixtures C11 (with 1% terphenyl) and C12 (with 3% terphenyl) which do not contain a compound of formula B.

(322) TABLE-US-00015 TABLE 4 Residual monomer content Residual RM [%] C11 P11 C31 C41 C51 80 min 0.0260 0.0164 0.0138 0.0333 0.0150

(323) From Table 4 it can be seen that polymerisable mixture P11 according to the present invention shows faster polymerisation with a significantly lower amount of residual RM, compared to polymerisable mixture C11 which does not contain a compound of formula B, and polymerisable mixture C41 which contains a terphenyl compound (PYP-2-3) different from formula T.

(324) Polymerisable mixture C31, which does not contain a compound of formula A, and polymerisable mixture C51, which does not contain a compound of formula A and contains a terphenyl compound (PYP-2-3) different from formula T, do both show a slightly lower amount of residual RM than polymerisable mixture P11, but do both have significantly higher viscosity than P11 as shown in Table 2 above.

(325) Overall polymerisable mixture P11 is therefore better suitable for PSA use than C11, C31, C41 and C51.

(326) TABLE-US-00016 TABLE 5 Residual monomer content Residual RM [%] C11 P11 C12 P12 80 min 0.0260 0.0164 0.0565 0.0477

(327) From Table 5 it can be seen that the polymerisable mixtures P11 (with M1) and P12 (with M2) according to the present invention show faster polymerisation with significantly lower amount of residual RM, compared to polymerisable mixtures C11 (with M1) and C12 (with M2), which do not contain a compound of formula B. This shows that the host mixture concept of the present invention can be used for different reactive mesogens.

(328) Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

(329) The entire disclosure[s] of all applications, patents and publications, cited herein and of corresponding EP application No. 15000176.6, filed Jan. 22, 2015, are incorporated by reference herein.

(330) The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

(331) From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.