Liquid crystal medium

Abstract

The present invention relates to a liquid crystal (LC) medium as defined in claim 1 and to a liquid crystal material and to the use thereof for optical, electro-optical and electronic purposes, in particular in energy saving LC displays, especially in IPS, FFS, VA or PS-VA displays.

Description

[0001] Liquid Crystal Medium

[0002] The present invention relates to a liquid crystal (LC) medium and to the use thereof for optical, electro-optical and electronic purposes, in particular in LC displays, especially in IPS, FFS, VA or PS-VA displays.

[0003] Liquid crystals (LCs) have found widespread use since the first commercially usable liquid-crystalline compounds were found. Liquid crystal displays (LCDs) are used in many areas for the display of information. LCDs are used both for direct-view displays and for projection-type displays.

[0004] One of the liquid crystal display modes used at present is the TN (“twisted nematic”) mode. However, TN LCDs have the disadvantage of a strong viewing-angle dependence of the contrast.

[0005] In addition, so-called VA (“vertically aligned”) displays are known which have a broader viewing angle. The LC cell of a VA display contains a layer of an LC medium between two transparent electrodes, where the LC medium usually has a negative dielectric anisotropy. In the switched-off state, the molecules of the LC layer are aligned perpendicular to the electrode surfaces (homeotropically) or have a tilted homeotropic alignment. On application of an electrical voltage to the two electrodes, a realignment of the LC molecules parallel to the electrode surfaces takes place.

[0006] Also known are so-called IPS (“in-plane switching”) displays, which contain an LC layer between two substrates, where the two electrodes are arranged on only one of the two substrates and preferably have intermeshed, comb-shaped structures. On application of a voltage to the electrodes, an electric field which has a significant component parallel to the LC layer is thereby generated between them. This causes realignment of the LC molecules in the layer plane.

[0007] Furthermore, so-called FFS (“fringe-field switching”) displays have been reported, see inter alia S. H. Jung et al., Jpn. J. Appl. Phys., Volume 43, No. 3, 2004, 1028, which contain two electrodes on the same substrate, one of which is structured in a combshaped manner and the other is unstructured. A strong, so-called "fringe field" is thereby generated, i.e. a strong electric field close to the edge of the electrodes, and, throughout the cell, an electric field which has both a strong vertical component and also a strong horizontal component. FFS displays have a low viewing-angle dependence of the contrast. FFS displays usually contain an LC medium with positive dielectric anisotropy, and an alignment layer, usually of polyimide, which provides planar alignment to the molecules of the LC medium.

[0008] FFS displays can be operated as active-matrix or passive-matrix displays. In the case of active-matrix displays, individual pixels are usually addressed by integrated, non-linear active elements, such as for example transistors, for example thin-film transistors ("TFTs"), while in the case of passive-matrix displays individual pixels are usually addressed by the multiplex method.

[0009] Typical applications of the in-plane switching (IPS) and fringe-field switching (FFS) electro-optical modes are desktop monitors, notebooks, TVs, mobile telephones, tablet PCs, etc. and multimedia applications. In general, dielectrically positive liquid-crystalline media having rather lower values of the dielectric anisotropy are used in FFS displays, but in some cases liquid-crystalline media having a dielectric anisotropy of only about 3 or even less are also used in IPS displays.

[0010] A further improvement has been achieved by the so-called “High Brightness FFS” (HB-FFS) mode. One of the favourable features of the HB-FFS mode in contrast to the traditional FFS technology is that it enables higher transmittance which allows operation of the panel with lower energy consumption.

[0011] Furthermore, FFS displays have been described in S. H. Lee et al., Appl. Phys. Lett.

[0012] 73(20), 1998, 2882-2883 and S. H. Lee et al., Liquid Crystals 39(9), 2012, 1141-1148, which have similar electrode design and layer thickness as FFS displays but comprise a layer of an LC medium with negative dielectric anisotropy instead of an LC medium with positive dielectric anisotropy. The LC medium with negative dielectric anisotropy can show a more favourable director orientation that has less tilt and more twist orientation compared to the LC medium with positive dielectric anisotropy, as a result of which these displays may have a higher transmission. The displays further comprise an alignment layer, preferably of polyimide provided on at least one of the substrates that is in contact with the LC medium and induces planar alignment of the LC molecules of the LC medium. These displays are also known as "Ultra Brightness FFS” (UB-FFS) mode displays. These displays require an LC medium with high reliability. Especially for monitor, mobile, video gaming and TV applications it is desirable to obtain favourably short response times, a wide viewing angle, low power consumption, a high transmittance and a suitably high contrast ratio of the LC displays.

[0013] It is inter alia desirable to provide displays with high brightness which at the same time can give favourable contrast, also under ambient light conditions. In this respect, it may in principle be considered to improve the image quality of the dark state in order to contribute to increasing the contrast ratio. For example, in general the retardation may be lowered by reducing the cell gap and / or by decreasing the optical anisotropy of the LC medium to improve the dark state quality. However, such a provision may negatively impact the device transmittance or brightness. It is in principle also possible to adjust the elastic constants of the LC medium to improve the dark state quality. Such an adjustment may however affect the operating voltage and the response time of the device.

[0014] There is still a need in the art for LC displays with a favourable electro-optical performance and reliability which offer broad applicability under various conditions, for example at different temperatures or different ambient light conditions or with reduced power consumption, and for liquid-crystalline media which can be suitably used in such LC displays.

[0015] It has presently been recognized that light leakage, in particular due to scattering, may detract from the dark or black state image quality and thus may also affect the obtainable contrast ratio.

[0016] An object of the present invention is therefore to provide improved liquid crystalline media for use in electro-optical devices and in particular displays with a favourable electro-optical performance, in particular with a high contrast ratio and a good black state while at the same time enabling high brightness or a high transmittance in one optical state, a low threshold voltage, fast addressing times and a favourable reliability in particular under light stress such as UV light and display backlight, and stability, in particular at low temperatures and at high temperatures. Further objects of the present invention are immediately evident to the person skilled in the art from the following detailed description.

[0017] Further, it is an object of the present invention to provide alternative media in addition to existing media known to the skilled person in order to broaden the range of available materials what allows for a more specific optimisation of a particular display. The objects are solved by the subject-matter defined in the independent claims, while preferred embodiments are set forth in the respective dependent claims and are further described below.

[0018] The present invention in particular provides the following items including main aspects, preferred embodiments and particular features, which respectively alone and in combination contribute to solving the above objects and eventually provide additional advantages.

[0019] The present invention relates to a liquid crystal medium comprising

[0020] a) a dichroic dye, and

[0021] b) one or more compounds of the formula I

[0022]

[0023] in which

[0024] W denotes CH4. Sor an aromatic hydrocarbon group having 6 to 40 C atoms or a heteroaromatic hydrocarbon group having 4 to 40 C atoms;

[0025] A on each occurrence, identically or differently, denotes a single bond or a straight chain alkylene radical having 1 to 20 C atoms or a straight chain alkenylene radical having 2 to 20 C atoms or a branched alkylene or alkenylene radical each having 3 to 12 C atoms, where one or more CH2groups in these radicals may each be replaced, independently of one another, by -C≡C-,-CH=CH-, -C(O)-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen and in which one or two H atoms may be replaced by a group -ZS-HA;

[0026] Rsdenotes H, alkyl having 1 to 12 C atoms or alkenyl having 2 to 12 C atoms;

[0027] Zsdenotes -O-, -C(O)O-, -(CH2)z- or -(CH2)2O-, or a single bond;

[0028] HA denotes

[0029]

[0030] RS1, RS2, RS3and RS4, identically or differently, denote alkyl having 1 to 6 C atoms, preferably having 1 to 3 C atoms, very preferably CH3;

[0031] G on each occurrence, identically or differently, denotes H or Rsor a group ZS-HA; z is an integer from 1 to 6;

[0032] t is 0 or 1, and

[0033] s is 2, 3 or 4;

[0034] with the proviso that if s is 2, t is 1 and at least one of the groups G denotes ZS-HA.

[0035] It has surprisingly been found that the use of a medium according to the invention in a display can favourably enhance the obtainable contrast ratio of an electro-optical devices, while it has been further found that at the same time a suitably high transmittance or brightness, fast response times, a low operating voltage and low power consumption and a wide viewing angle of the devices may be maintained, where the medium exhibits an unexpectedly high stability against heat and light stress, in particular against UV or display backlight irradiation.

[0036] According to the invention the one or more dichroic dyes are provided in relatively small and limited yet effective amounts in the liquid-crystalline media to efficiently improve the dark state and the overall contrast of the devices and in particular displays, e.g., FFS, HB-FFS and especially UB-FFS displays, without however affecting the desired device transmittance or brightness or only reducing the device transmittance or brightness to a minimal or even negligible extent.

[0037] According to the invention the liquid-crystalline medium comprises one or more dichroic dyes, preferably in a total amount of 2.0% by weight or less. In a preferred embodiment the total amount of the one or more dichroic dyes in the liquid-crystalline medium is 1.0% by weight or less. It is further preferred that the total amount of the one or more dichroic dyes in the liquid-crystalline medium is 0.5% by weight or less, more preferably 0.2% by weight or less.

[0038] Herein, a dichroic dye is taken to mean a light-absorbing compound in which the absorption properties are dependent on the orientation of the compound relative to the direction of polarization of the light. A dichroic dye compound in accordance with the present invention typically has an elongated shape, i.e., the compound is significantly longer in one spatial direction, i.e., along the longitudinal axis, than in the other two spatial directions. The dichroic dye absorbs, or respectively preferentially absorbs, light in one orientation so that light transmission may be modulated by changing the orientation of the dichroic dye. According to the invention a so-called liquid crystal host is doped with dichroic dye molecules in relatively small, limited amounts. These dye-doped LC media are used particularly preferably for FFS and UB-FFS modes, however also other display modes as described above and below can be employed.

[0039] The liquid crystal medium according to the invention comprises a liquid crystal host which consists of a multitude of mesogenic compounds and is preferably nematic.

[0040] 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.

[0041] The liquid crystal medium according to the invention has positive or negative dielectric anisotropy.

[0042] In formula I, W may denote an aromatic or heteroaromatic hydrocarbon group having 4 to 40 C atoms. The aromatic or heteroaromatic hydrocarbon group may comprise one, two, three or four aromatic or heteroaromatic rings including condensed rings that may be linked directly or via an alkylene linking group having 1 to 12 C atoms, in which one or more H atoms are optionally replaced with alkyl or alkoxy having 1 to 6 C atoms or alkenyl having 2 to 6 C atoms, or with CN, CF3 or halogen, and in which one or more CH2 groups may each, independently of one another, be replaced by -O-, -S-, -NH-, -N(Ci-C4-alkyl)-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH- or -C≡C- in such a way that O or S atoms are not linked directly to one another. Preferred are benzene, naphthalene, anthracene, biphenyl, m-terphenyl, p-terphenyl, and (phenylalkyl)benzene in which alkyl is straight chain alkyl having 1 to 12 C atoms.

[0043] The medium according to the invention preferably comprises the one or more compounds of the formula I in a total concentration in the range of from 1 ppm to 2000 ppm, more preferably from 250 ppm to 1500 ppm, still more preferably from 500 ppm to 1300 ppm, very preferably from 750 ppm to 1200 ppm and in particular from 900 ppm to 1100 ppm.

[0044] The compounds of formula I are preferably selected from the compounds of the formulae 1-1, I-2 and I-3:

[0045]

[0046]

[0047] in which

[0048] n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7, and

[0049] Sp denotes a spacer group, preferably alkylene having 1 to 12 C atoms in which one or more non-adjacent -CH2- groups may be replaced with -O-.

[0050] Very preferred are the compounds of the formula 1-1.

[0051] Preferred compounds of formula 1-1 are selected from the compounds of the formula

[0052]

[0053] in which n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0054] Preferred compounds of formula I-2 are selected from the compounds of the formula 1-2-1:

[0055]

[0056] in which n2, on each occurrence identically or differently, preferably identically, is an integer from 1 to 12, preferably 2, 3, 4, 5, or 6, very preferably 3, and Rson each occurrence identically or differently, preferably identically, denotes alkyl having 1 to 6 C atoms, preferably n-butyl.

[0057] Preferred compounds of formula I-3 are selected from the compounds of the formula 1-3-1:

[0058]

[0059] in which n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7. Preferably, the medium according to the invention comprises a compound selected from the group of compounds of the formulae ST-1 to ST-21:

[0060]

[0061]

[0062]

[0063]

[0064] in which

[0065] RSTdenotes H, an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH2groups in these radicals may each be replaced,

[0066]

[0067] -O-CO- in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen,

[0068] each occurrence, identically or differently, denotes

[0069]

[0070]

[0071] ZSTeach, independently of one another, denote -CO-O-, -O-CO-, -CF₂O-, -OCF₂-, -CH₂O-, -OCH₂-, -CH₂-, -CH₂CH₂-, -(CH₂)₄-, -CH=CH-, -CH₂O-, -C₂F₄-, -CH₂CF₂-, -CF₂CH₂-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond,

[0072] L1and L2each, independently of one another, denote F, Cl, CH₃, CF₃ or CHF₂, p denotes 0, 1 or 2,

[0073] q denotes 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10,

[0074] n2 on each occurrence identically or differently, preferably identically, is an integer from 1 to 12, preferably 2, 3, 4, 5, or 6, very preferably 3,

[0075] Rson each occurrence identically or differently, preferably identically, denotes alkyl having 1 to 6 C atoms, preferably n-butyl.

[0076] Of the compounds of the formula ST, special preference is given to the following compounds:

[0077]

[0078]

[0079] in which n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 1 or 7

[0080]

[0081]

[0082]

[0083] In the compounds of the formulae ST-3a and ST-3b, n preferably denotes 3. In the compounds of the formula ST-2a, n preferably denotes 7.

[0084] Very particularly preferred mixtures according to the invention comprise one or more stabilizers from the group of the compounds of the formulae ST-2a-1, ST-3a-1, ST- 3b- 1, ST-8-1, ST-9-1 and ST-12:

[0085]

[0086]

[0087] The compounds of the formulae ST-1 to ST-21 are preferably each present in the liquid-crystal mixtures according to the invention in amounts of 0.005 – 0.5%, based on the mixture.

[0088] Preferably, the dichroic dye compounds are present in the liquid-crystalline medium in solution. The dichroic dye molecules as used according to the invention therefore preferably exhibit suitable and sufficient solubility in the liquid crystal host. In addition, the dye compounds preferably also favourably contribute to the stability and reliability of the media.

[0089] Each of the one or more dichroic dyes is preferably present in the liquid-crystalline medium in a proportion of 0.002% by weight to 2.0% by weight, more preferably 0.003% by weight to 1.0% by weight, still more preferably 0.005% by weight to 0.5% by weight, even more preferably 0.01% by weight to 0.3% by weight, and particularly preferably 0.02% by weight to 0.2% by weight, based on the overall weight of the entire medium.

[0090] Preferably, the one or more dichroic dyes are present in the liquid-crystalline medium overall in a total concentration which is in the range of from 0.003% by weight to 2.0% by weight, more preferably 0.004% by weight to 1.5% by weight, still more preferably 0.005% by weight to 1.0% by weight, yet more preferably 0.01% by weight to 0.5% by weight, even more preferably 0.02% by weight to 0.3% by weight, and particularly preferably 0.05% by weight to 0.2% by weight.

[0091] The concentration of the dye(s) is favourably chosen such that the proper performance of the obtained liquid-crystalline material is ensured, in particular in terms of the desired reduction of the light leakage in the dark state and the improved black image quality and overall contrast, while suitably maintaining other device properties such as response times, operating voltage and brightness. The upper limit of the dye concentration is provided in particular in view of maintaining the bright state performance of the device such that transmittance is not affected or only to a minimal extent.

[0092] Dichroic dyes may preferably be selected from for example azo dyes, anthraquinones, thiophenolanthraquinones, methine compounds, azomethine compounds, merocyanine compounds, naphthoquinones, tetrazines, pyrromethene dyes, malononitrile dyes, nickel dithiolenes, (metal) phthalocyanines, (metal) naphthalocyanines and (metal) porphyrins, rylenes, in particular perylenes and terylenes, thiadiazole dyes, thienothiadiazole dyes, benzothiadiazoles, thiadiazoloquinoxalines, and diketopyrrolopyrroles. Particular preference is given to azo compounds, anthraquinones, thiophenolanthraquinones, benzothiadiazoles, in particular as described in WO 2014 / 187529 and in WO 2020 / 104563 A1, diketopyrrolopyrroles, in particular as described in WO 2015 / 090497, thiadiazoloquinoxalines, in particular as described in WO 2016 / 177449 and in WO 2020 / 104563 A1, and rylenes, in particular as described in WO 2014 / 090373.

[0093] In a preferred embodiment the one or more dichroic dyes are selected from azo compounds, benzothiadiazoles and thiadiazoloquinoxalines.

[0094] The liquid-crystalline medium preferably comprises one, two, three, four, five, six, seven, eight, nine or ten different dichroic dyes, particularly preferably two, three, four, five or six dichroic dyes. In a preferred embodiment the medium contains at least three different dichroic dyes.

[0095] In an embodiment the absorption spectra of the dichroic dyes contained in the medium or respectively the switchable layer preferably complement one another in such a way that the impression of a black colour, or respectively a colour-neutral appearance, arises for the eye. Preferably two or more, more preferably three or more dichroic dyes are used in the liquid-crystalline medium to preferably cover a large part of the visible spectrum. The precise way in which a mixture of dyes which appears black or grey to the eye can be prepared is known in the art and is described, for example, in M. Richter, Einführung in die Farbmetrik [Introduction to Colorimetry], 2nd Edition, 1981, ISBN 311-008209-8, Walter de Gruyter & Co.

[0096] The setting of the colour location of a mixture of dyes is described in the area of colorimetry. To this end, the spectra of the individual dyes are calculated taking into account the Lambert-Beer law to give an overall spectrum and converted into the corresponding colour locations and luminance values under the associated illumination, for example illuminant D65 for daylight, in accordance with the rules of colorimetry. The position of the white point is fixed by the respective illuminant, for example D65, and is quoted in tables, for example in the reference above. Different colour locations can be set by changing the proportions of the various dyes.

[0097] According to a preferred embodiment, the medium and the switchable layer comprise one or more dichroic dyes which absorb light in the visible spectrum, which herein is defined as light having a wavelength of from 380 nm to 780 nm. In an embodiment the dichroic dyes provided in the medium and the switchable layer are preferably selected from the dye classes indicated in B. Bahadur, Liquid Crystals -Applications and Uses, Vol. 3, 1992, World Scientific Publishing, Section 11.2.1, and particularly preferably from the explicit compounds given in the table present therein.

[0098] Said dyes belong to the classes of dichroic dyes which are known in the art and have been described in the literature. Thus, for example, anthraquinone dyes are described in EP 34832, EP 44893, EP 48583, EP 54217, EP 56492, EP 59036, GB 2065158, GB 2065695, GB 2081736, GB 2082196, GB 2094822, GB 2094825, JP A 55-123673, DE 3017877, DE 3040102, DE 3115147, DE 3115762, DE 3150803 and DE 3201120, naphthoquinone dyes are described in DE 3126108 and DE 3202761, azo dyes in EP 43904, DE 3123519, WO 82 / 2054, GB 2079770, JP-A 56-57850, JP-A 56-104984, US 4308161, US 4308162, US 4340973, T. Uchida, C. Shishido, H. Seki and M. Wada: Mol. Cryst. Liq. Cryst. 39, 39-52 (1977), and H. Seki, C. Shishido, S. Yasui and T. Uchida: Jpn. J. Appl. Phys. 21, 191-192 (1982), and perylenes are described in EP 60895, EP 68427 and WO 82 / 1191. Rylene dyes as described, for example, in EP 2166040, US 2011 / 0042651, EP 68427, EP 47027, EP 60895, DE 3110960 and EP 698649.

[0099] Very preferred dyes are selected from the compounds of the formulae Dye-1 to Dye-10:

[0100]

[0101]

[0102]

[0103] in which R independently denotes straight chain alkyl having 1 to 20 C atoms, or branched alkyl having 3 to 20 C atoms, or straight chain alkenyl having 2 to 20 C atoms, or branched alkenyl having 3 to 20 C atoms, and (O) denotes O or a single bond.

[0104] In an embodiment the medium according to the present disclosure has positive dielectric anisotropy and preferably comprises one or more compounds selected from the group of compounds of the formulae II and III

[0105]

[0106] in which

[0107] R2and R3have the meanings given above for R11, preferably denote alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms,

[0108]

[0109] L21, L22, L31and L32independently of each other, denote H or F,

[0110] Y2and Y3identically or differently, denote H or CH3, preferably H,

[0111] X2and X3independently of each other, denote halogen, halogenated alkyl or halogenated alkoxy with 1 to 3 C-atoms or halogenated alkenyl or halogenated alkenyloxy with 2 or 3 C-atoms, preferably F, Cl, CF3, OCF3or OCHF2, more preferably F or OCF3,

[0112] Z3denotes -CH2CH2-, -CF2CF2-, -COO-, trans- -CH=CH-, trans-CF=CF-,

[0113] -CH2O- or a single bond, preferably a single bond, and I, m, n and o are, independently of each other, 0 or 1,

[0114] and where the compounds of the formula CL are excluded from formula III and its sub-formulae.

[0115] The one or more compounds selected from the group of compounds of the formulae II and III are preferably contained in the medium in a total concentration in the range of from 2% to 50%.

[0116] Preferably, the medium comprises one or more compounds of formula II, more preferably selected from the group of compounds of formulae 11-1 to II-3, very preferably from the group of compounds of the formulae 11-1 and 11-3

[0117]

[0118] in which the occurring groups have the respective meanings given under formula II above and in formula 11-1 the radicals L23and L24denote, independently of each other, H or F and in formula II-2 preferably

[0119]

[0120] In formulae 11-1, II-2 and II-3, L21and L22or L23and L24are preferably both F.

[0121] In another preferred embodiment in formulae 11-1 and II-2, all of L21, L22, L23and L24denote F.

[0122] The compounds of formula 11-1 are preferably selected from the group of compounds of the formulae 11-1 a to 11-1 h

[0123]

[0124]

[0125] in which the occurring groups have the respective meanings given above.

[0126] In a preferred embodiment of the present invention the medium comprises one or more compounds selected from the group of compounds of the formulae 11-1 a to 11-1 h wherein L21and L22, and / or L23and L24are both F, respectively.

[0127] In another preferred embodiment the medium comprises compounds selected from the group of compounds of formulae 11-1 a to 11-1 h, wherein L21, L22, L23and L24all are F.

[0128] Especially preferred compounds of formula 11-1 are

[0129]

[0130] in which R2has the meaning given above.

[0131] Preferably the compounds of formula II-2 are selected from the group of compounds of formulae I l-2a to I l-2c

[0132]

[0133] in which the occurring groups have the respective meanings given above and preferably L21and L22are both F.

[0134] Preferably the compounds of formula II-3 are selected from the group of compounds of formulae I l-3a to I l-3e

[0135]

[0136]

[0137] in which the occurring groups have the respective meanings given above and preferably

[0138] L21and L22are both F and L23and L24are both H or

[0139] L21, L22, L23and L24are all F.

[0140] Especially preferred compounds of formula II-3 are

[0141]

[0142]

[0143] in which R2has the meaning given above.

[0144] In addition to the preferred compounds of formula II above the medium optionally comprises one or more compounds of formula II selected from the compounds of

[0145]

[0146]

[0147]

[0148]

[0149]

[0150] in which R2and X2have the meanings given in formula II or one of the preferred meanings given above and below.

[0151] In the compounds of formulae I IA1 to IIA28, R2preferably denotes alkyl having 1 to 6 C atoms, very preferably ethyl or propyl, X2 preferably denotes F or OCF3, very preferably F.

[0152] In another preferred embodiment of the present invention the medium comprises one or more compounds of formula III preferably selected from the group of formulae III-1 and III-2, preferably of formula III-2:

[0153]

[0154] in which the occurring groups and parameters have the respective meanings given under formula III above.

[0155] R3preferably denotes alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms.

[0156] Preferably the compounds of formula III-1 are selected from the group of compounds of formulae II 1-1 a and 111-1 b:

[0157]

[0158] in which the occurring groups have the respective meanings given above and L33and L34, independently of each other, denote H or F.

[0159] The compounds of formula 111-1 a are preferably selected from the group of compounds of formulae lll-1a-1 to lll-1a-6

[0160]

[0161]

[0162] in which R3has the meaning given above.

[0163] Preferably the compounds of formula III-2 are selected from the group of compounds of formulae lll-2a to lll-2n

[0164]

[0165]

[0166]

[0167] in which the occurring groups have the respective meanings given above and L35and L36, independently of one another, denote H or F.

[0168] Preferably, the compounds of formula III-2a are selected from the group of compounds of formulae III-2a-1 to III-2a-4

[0169]

[0170] in which R3has the meaning given above.

[0171] The compounds of formula III-2b are preferably selected from the group of compounds of formulae III-2b-1 and III-2b-2, preferably III-2b-2

[0172]

[0173]

[0174] in which R3has the meaning given above.

[0175] The compounds of formula III-2c, are preferably selected from the group of compounds of formulae III-2c-1 to III-2c-5

[0176]

[0177] in which R3has the meaning given above.

[0178] The compounds of formulae III-2d and III-2e are preferably selected from the group of compounds of formulae III-2d-1 and III-2e-1

[0179] lll-2d-1

[0180]

[0181]

[0182] in which R3has the meaning given above.

[0183] The compounds of formula III-2f are preferably selected from the compounds of the formula III-2f-1

[0184]

[0185] in which R3has the meaning given above.

[0186] The compounds of formula III-2g are preferably selected from the group of compounds of formulae III-2g-1 to III-2g-7

[0187]

[0188]

[0189] in which R3has the meaning given above.

[0190] The compounds of formula III-2h are preferably selected from the group of compounds of formulae III-2h-1 to III-2h-5

[0191]

[0192]

[0193] lll-2h-5 in which R3has the meaning given above.

[0194] The compounds of formula III-2i are preferably selected from the group of compounds of formulae III-2i-1 to III-2i-3

[0195]

[0196] in which R3has the meaning given above.

[0197] The compounds of formula III-2j are preferably selected from the group of compounds of formulae III-2j-1 to III-2j-3

[0198]

[0199]

[0200] in which R3has the meaning given above.

[0201] The compounds of formula III-2k are preferably selected from the group of compounds of formulae III-2k-1 to III-2k-6

[0202]

[0203] in which R3has the meaning given above.

[0204] The compounds of formula III-2I are preferably selected from the group of compounds of formulae III-2I- 1 to III-2I-6

[0205]

[0206] The compounds of formula III-2m are preferably selected from the compounds of formula III-2m-1

[0207]

[0208] in which R3has the meaning given above.

[0209] The compounds of formula III-2n are preferably selected from the compounds of formula III-2n-1

[0210]

[0211] in which R3has the meaning given above.

[0212] Alternatively, or in addition to the compounds of the formulae III-1 and / or III-2 the media according to the present invention optionally comprise one or more compounds of formula III-3,

[0213]

[0214] in which the groups and parameters have the respective meanings given under formula III above,

[0215]

[0216] in which the R3has the meaning given above.

[0217] In another embodiment, the medium according to the invention has negative dielectric anisotropy and preferably comprises one or more compounds selected from the group of compounds of the formulae NIIA, NIIB, NIIC and NIID

[0218]

[0219] in which

[0220] R2A, R2B, R2Cand R2Didentically or differently, denote H, straight chain alkyl or alkoxy having 1 to 15 C atoms, straight chain alkenyl or alkenyloxy having 2 to 15 C atoms or branched alkyl, alkoxy, alkenyl, alkenyloxy each having 3 to 15 C atoms, where one or more CH2groups in these radicals may each be replaced, independently of one another,

[0221]

[0222] that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen,

[0223] L1and L2, each, independently of one another, denote F, Cl, CF3 or CHF2,

[0224] Y denotes H, F, Cl, CF3, CHF2or CH3, preferably H or CH3, more preferably H, Z2, Z2Band Z2Deach, independently of one another, denote a single

[0225] bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF- or -CH=CHCH2O-,

[0226] p denotes 0, 1 or 2, q denotes 0 or 1, and

[0227] v denotes an integer from 1 to 6.

[0228] The one or more compounds selected from the group of compounds of the formulae NIIA, NIIB, and NIID are preferably contained in the medium according to the invention in a total concentration in the range of from 5% to 60%, preferably at least 20% by weight.

[0229] The one or more compounds selected from the group of compounds of the formulae NIIA, NIIB, and NIID are preferably contained in the medium according to the invention in a total concentration of at least 20% by weight.

[0230] The one or more compounds of the formula NIIC are preferably contained in the medium according to the invention in an amount of > 3% by weight, in particular > 5% by weight and particularly preferably in an amount of 5-25% by weight.

[0231] Preferred compounds of the formulae NIIA, NIIB, NIIC and NIID are indicated below:

[0232]

[0233]

[0234]

[0235]

[0236]

[0237]

[0238]

[0239]

[0240]

[0241]

[0242]

[0243]

[0244]

[0245] in which the parameter 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 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 denotes CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0246] The compounds of the formulae NIID-4 and NIID-10 are very preferred, where (O) in particular denotes O.

[0247] Very preferred compounds of the formula N 11 D are selected from the following subformulae:

[0248]

[0249]

[0250]

[0251]

[0252]

[0253] In a preferred embodiment, the medium comprises one or more compounds of formula NIID-10a

[0254]

[0255] in which the occurring groups and parameters have the meanings given above under formula NIID, and

[0256] — (CH2)r— <1

[0257] R2denotes (CH2)s, in which r is 0, 1, 2, 3, 4, 5 or 6 and s is 1, 2 or 3.

[0258] Preferred compounds of formula NIID-10a are the compounds NIID-10a-1 to NIID-10a-14.

[0259]

[0260]

[0261]

[0262]

[0263]

[0264]

[0265]

[0266]

[0267]

[0268] Particularly preferred mixtures according to the invention comprise one or more compounds of the formulae NIIA-2, NIIA-8, NIIA-10, NIIA-16, NIIA-18, NIIA-40, NIIA-41, NIIA-42, NIIA-43, NIIB-2, NIIB-10, NIIB-16, NIIC-1, NIID-4, and NIID-10.

[0269] Preferred media according to the invention comprise at least one compound of the formula NIIC-1,

[0270]

[0271] NIIC-1

[0272] in which alkyl and alkyl* have the meanings indicated above.

[0273] In particular, the medium comprises one or more compounds of the formula NIIA-2 selected from the following sub-formulae:

[0274]

[0275] NIIA-2-5

[0276]

[0277] Alternatively, preferably in addition to the compounds of the formulae NIIA-2-1 to NIIA-2-5, the medium comprises one or more compounds of the formulae NIIA-2a-1 to NIIA-2a-5:

[0278]

[0279] In particular, the medium comprises one or more compounds of the formula NIIA-10 selected from the following sub-formulae:

[0280] NIIA-10-1

[0281]

[0282]

[0283] Alternatively, preferably in addition to the compounds of the formulae NIIA-10-1 to NIIA- 10-5, the medium comprises one or more compounds of the formulae NIIA-10a-1 to NIIA- 10a-5:

[0284]

[0285] NIIA-

[0286]

[0287] 10a-5

[0288] In particular, the medium comprises one or more compounds of the formula NIIB-10 selected from the following sub-formulae:

[0289]

[0290] Alternatively, preferably in addition to the compounds of the formulae NIIB-10-1 to NIIB-10-5, the medium comprises one or more compounds of the formulae NIIB-10a-1 to NIIB- 10a-5:

[0291] NIIB-10a-1

[0292]

[0293]

[0294] Alternatively, preferably in addition to the compounds of the formulae NIIC-1, the medium comprises one or more compounds of the formulae NIIC-1a-1 and NIIC-1a-2

[0295]

[0296] in which alkyl denotes straight chain alkyl having 1 to 7 C atoms, preferably 2 to 5 C atoms, very preferably denotes ethyl.

[0297] The medium according to the invention preferably comprises one or more compounds of formula NIII

[0298]

[0299] in which

[0300] R31and R32each, independently of one another, denote H, an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more CH2 groups in these radicals may each be

[0301]

[0302] -OCF2-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen,

[0303] A31on each occurrence, independently of one another, denotes

[0304] a) 1,4-cyclohexenylene or 1,4-cyclohexylene radical, in which one or two non-adjacent CH2 groups may be replaced by -O- or -S-,

[0305] b) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N, or c) a radical from the group spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl,

[0306] where the radicals a), b) and c) may be mono- or polysubstituted by halogen atoms, n is 0, 1 or 2, preferably 0 or 1,

[0307] Z31on each occurrence independently of one another denotes -CO-O-,

[0308] -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-,

[0309] -CH=CH-CH2O-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-,

[0310] -CF=CH-, -CH=CH-, -C≡C- or a single bond, and

[0311] L31and L32each, independently of one another, denote F, Cl, CF3 or CHF2, preferably H or F, most preferably F, and

[0312] W denotes O or S.

[0313] The one or more compounds of the formula NIII is preferably contained in the medium according to the invention in a total concentration in the range of from 1% to 20%.

[0314] The compounds of formula NIII are preferably selected from the compounds of the formula NIII-1 and / or NIII-2

[0315]

[0316] in which the occurring groups have the same meanings as given under formula NIII above and preferably

[0317] R31and R32each, independently of one another, an alkyl, alkenyl or alkoxy radical having up to 15 C atoms, more preferably one or both of them denote an alkoxy radical and L31and L32each preferably denote F.

[0318] Preferably, the compounds of the formula NIII-1 are selected from the group of compounds of the formulae NIII-1-1 to NIII-1-11, preferably of formula NIII-1-6,

[0319]

[0320]

[0321] alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl 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, alkoxy and alkoxy* each, independently of one another, denote a straight-chain alkoxy radical having 1-6 C atoms, and L31and L32each, independently of one another, denote F or Cl, preferably both F.

[0322] Preferably, the compounds of the formula NIII-2 are selected from the group of compounds of the formulae NIII-2-1 to NIII-2-10, preferably of formula NIII-2-6,

[0323]

[0324]

[0325] alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl 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, alkoxy and alkoxy* each, independently of one another, denote a straight-chain alkoxy radical having 1-6 C atoms, and L31and L32each, independently of one another, denote F or Cl, preferably both F.

[0326] Optionally the medium comprises one or more compounds of the formula NIIIA-1 and / or NIIIA-2

[0327]

[0328] in which L31and L32have the same meanings as given under formula NIII, (O) denotes O or a single bond,

[0329] RNIIIAdenotes alkyl or alkenyl having up to 7 C atoms or a group Cy-CmH2m+1-,

[0330] m and n are, identically or differently, 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1,

[0331] Cy denotes a cycloaliphatic group having 3, 4 or 5 ring atoms, which is optionally substituted with alkyl or alkenyl each having up to 3 C atoms, or with halogen or CN, and preferably denotes cyclopropyl, cyclobutyl, cyclopentyl, cyclopent- 1-enyl, cyclopent-2-enyl and cyclopent-3-enyl. The compounds of formula NIIIA-1 and / or NIIIA-2 are contained in the medium either alternatively or in addition to the compounds of formula NIII, preferably additionally.

[0332] Very preferred compounds of the formulae NIIIA-1 and NIIIA-2 are the following:

[0333]

[0334] NIIIA-2-2 alkoxy

[0335]

[0336] NIIIA-2-3 alkoxy

[0337]

[0338] NIIIA-2-4 alkoxy

[0339]

[0340] NIIIA-2-5 alkoxy

[0341]

[0342] NIIIA-2-6 alkoxy

[0343]

[0344] in which alkoxy denotes a straight-chain alkoxy radical having 1-6 C atoms or alternatively -(CH2)nF in which n is 2,3,4, or 5, preferably C2H4F.

[0345] In a preferred embodiment of the present invention, the medium comprises one or more compounds of formula NIII-3

[0346] NIII-3

[0347]

[0348] in which

[0349] R31, R32identically or differently, denote H, an alkyl or alkoxy radical having 1 to 15 C atoms, in which one or more CH2groups in these radicals are optionally replaced,

[0350] independently of one another, by -C≡C-, -CF2O-, -OCF2-, -CH=CH-,

[0351]

[0352]

[0353] ed directly to one another, and in which one or more H atoms may be replaced by halogen. The compounds of formula NIII-3 are preferably selected from the group of compounds of the formulae NIII-3-1 to NIII-3-10:

[0354]

[0355]

[0356] in which R32denotes alkyl having 1 to 7 C-atoms, preferably ethyl, n-propyl or n-butyl, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl or alternatively -(CH2)nF in which n is 2,3,4, or 5, preferably C2H4F.

[0357] In a preferred embodiment of the present invention, the medium comprises one or more compounds of the formulae NIII-4 to NIII-6, preferably of formula NIII-5,

[0358]

[0359] in which the parameters have the meanings given above, R31preferably denotes straightchain alkyl and R32preferably denotes alkoxy, each having 1 to 7 C atoms.

[0360] In a preferred embodiment the medium comprises one or more compounds of the formula NIII selected from the group of compounds of formulae NIII-7 to NIII-9, preferably of formula

[0361]

[0362]

[0363] in which the parameters have the meanings given above, R31preferably denotes straightchain alkyl and R32preferably denotes alkoxy each having 1 to 7 C atoms.

[0364] Preferably, the medium comprises one or more compounds of the formula IV,

[0365]

[0366] in which

[0367] R41denotes an alkyl radical having 1 to 7 C atoms or an alkenyl radical having 2 to 7 C atoms, preferably an n-alkyl radical, particularly preferably having 2, 3, 4 or 5 C atoms, and

[0368] R42denotes an alkyl radical having 1 to 7 C atoms or an alkoxy radical having 1 to 6 C atoms, both preferably having 2 to 5 C atoms, an alkenyl radical having 2 to 7 C atoms, preferably having 2, 3 or 4 C atoms, more preferably a vinyl radical or a 1 -propenyl radical and in particular a vinyl radical.

[0369] The total concentration of the one or more compounds of the formula IV in the medium is preferably in the range of from 5% to 70%, more preferably 20% to 65%, still more preferably 30% to 60% and very preferably 40% to 55%.

[0370] The compounds of the formula IV are preferably selected from the group of the compounds of the formulae IV-1 to IV-4,

[0371]

[0372]

[0373] in which

[0374] alkyl and alkyl’, independently of one another, denote alkyl having 1 to 7 C atoms, preferably having 1 to 5 C atoms,

[0375] alkenyl denotes an alkenyl radical having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably 2 C atoms,

[0376] alkenyl’ denotes an alkenyl radical having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms, and

[0377] alkoxy denotes alkoxy having 1 to 5 C atoms, preferably having 2 to 4 C atoms.

[0378] The compounds of the formula IV- 1 are preferably selected from the group of compounds of the formulae IV-1-1 to IV-1-6

[0379]

[0380] The compounds of the formula IV-2 are preferably selected from the compounds of the formulae IV-2-1 and IV-2-2

[0381]

[0382] The compounds of the formula IV-3 are preferably selected from the group of the compounds of the formulae IV-3-1, IV-3-2 and IV-3-3:

[0383]

[0384] in which alkyl has the meanings defined above and where the compound of the formula I is excluded from formula IV-3-2.

[0385] The compounds of the formula IV-3-1, IV-3-2 and IV-3-3 are preferably selected from the following compounds:

[0386]

[0387]

[0388] Very preferably, the medium according to the invention comprises a compound of formula IV-4, in particular selected from the compounds of the formulae IV-4-1 to IV-4-3

[0389]

[0390] The liquid-crystalline medium preferably additionally comprises one or more compounds of the formula IVa,

[0391]

[0392] in which

[0393] R41and R42each, independently of one another, denote a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkoxy radical having up to 12 C atoms, and

[0394]

[0395] in which

[0396] alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1 to 6 C atoms.

[0397] The medium according to the invention preferably comprises at least one compound of the formula IVa-1 and / or formula IVa-2.

[0398] The proportion of compounds of the formula IVa in the mixture as a whole is preferably less than 5 % by weight, very preferably less than 2% by weight. Preferably, the medium comprises one or more compounds of formula IVb-1 to IVb-4, more preferably of the compounds of the formulae IVb-1 to IVb-3

[0399]

[0400] in which

[0401] alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1 to 6 C atoms, and

[0402] alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2 to 6 C atoms.

[0403] Of the compounds of the formulae IVb-1 to IVb-3, the compounds of the formula IVb-2 are particularly preferred.

[0404] Particularly preferred biphenyls are

[0405]

[0406]

[0407] in which alkyl* denotes an alkyl radical having 1 to 6 C atoms and preferably denotes n-propyl. The medium according to the invention particularly preferably comprises one or more compounds of the formulae IVb-1-1 and / or IVb-2-3.

[0408] In a preferred embodiment, the medium according to the invention comprises one or more compounds of formula V

[0409]

[0410] in which

[0411] R51, R52denote alkyl having 1 to 7 C atoms, alkoxy having 1 to 7 C atoms, or alkoxyalkyl, alkenyl or alkenyloxy having 2 to 7 C atoms,

[0412]

[0413] Z51, Z52each, independently of one another, denote -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, and

[0414] n is 1 or 2,

[0415] where the compounds of the formula CL are excluded.

[0416] The compounds of the formula V are preferably contained in the medium in a total concentration in the range of from 5% to 50%. The compounds of formula V are preferably selected from the compounds of the formulae

[0417]

[0418] in which the groups occurring have the meanings given above for formula V.

[0419] The compounds of formula V-1 are preferably selected from the compounds of the formulae V-1-1 to V-1-8;

[0420] the compounds of formula V-2 are preferably selected from the compounds of the formulae V-2-1 to V-2-4; and

[0421] the compounds of formula V-3 are preferably selected from the compounds of the formulae V-3-1 to V-3-7:

[0422]

[0423]

[0424]

[0425] in which R51and R52have the meanings indicated for formula V above.

[0426] R51and R52preferably each, independently of one another, denote straight-chain alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms.

[0427] Very preferred compounds of the formula V-2-1 are selected from the compounds of the formulae V-2-1 a to V-2-1 g

[0428]

[0429]

[0430] Very preferred compounds of the formula V-2-2 are selected from the compounds of the formulae V-2-2a to V-2-2i

[0431]

[0432]

[0433] Preferably, the medium according to the invention comprises one or more compounds of the formula CL

[0434]

[0435] RLdenotes H, a straight chain or branched alkyl or alkoxy radical having 1 to 15 C atoms, or a straight chain or branched alkenyl radical having 2 to 15 C atoms, where one or more CH2groups in these radicals may each be replaced, independently of one

[0436] another,

[0437]

[0438] -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen,

[0439] XLdenotes F, Cl, CN, CHF2, CF3, OCF3, or, identically or differently, has one of the meanings of RL,

[0440] YLdenotes H, F, Cl or CH3. The one or more compounds of the formula CL are preferably contained in the medium in a total concentration in the range of from 0.5% to 20%.

[0441] The compounds of formula CL are preferably selected form the group of compounds of the formulae CL-1, CL-2 and CL-3:

[0442]

[0443] in which

[0444] RL1and RL2, identically or differently, have the meanings given above for formula I and, preferably denote alkyl or alkenyl having 1 to 7 C atoms or 2 to 7 C atoms, respectively, in which a CH2group may be replaced by cyclopropane-1,2-diyl, and RL2alternatively denotes alkoxy having 1 to 5 C atoms.

[0445] Very preferred compounds of the formula CL-3 are selected from the compounds of the formulae CL-3-1 to CL-3-12:

[0446]

[0447]

[0448] CL-3-15

[0449]

[0450] In a particularly preferred embodiment, the medium according to the invention comprises the compound CL-3-1 or CLP-3-3.

[0451] In a preferred embodiment of the present invention the medium additionally comprises one or more compounds of the formula VI,

[0452]

[0453] in which

[0454] R61and R62denote H, F, straight chain alkyl or alkoxy having 1 to 15 C atoms, straight chain alkenyl or alkenyloxy having 2 to 15 C atoms or branched alkyl, alkoxy, alkenyl, alkenyloxy each having 3 to 15 C atoms, where one or more CH2groups in

[0455] these radicals may each be replaced, independently of one another, by

[0456]

[0457]

[0458] -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen,

[0459] X61, X62, X63, X64, X65, and X66, identically or differently, denote H or F, preferably at least one of X61, X62, X63, X64, X65, and X66denotes F, more preferably at least two of X61, X62, X63, X64, X65, and X66denote F;

[0460] Z61and Z62, identically or differently, denote CH2CH2or a single bond

[0461] n6 is 0 or 1, preferably 1,

[0462] wherein the compounds of the formula NIIB are excluded.

[0463] The one or more compounds of the formula VI are preferably contained in the medium in a total concentration in the range of from 1% to 30%.

[0464] The compounds of the formula VI are preferably selected from the formulae VI-1 and VI-2:

[0465]

[0466] in which the occurring groups have the meanings given for formula VI.

[0467] The compounds of the formula VI-1 are preferably selected from the formulae VI-1-1 to VI-1-21, very preferably of the formula VI-1-4:

[0468]

[0469]

[0470]

[0471] in which R6denotes a straight-chain alkyl or alkoxy radical having 1 to 6 C atoms, (O) denotes -O- or a single bond, and m is 0, 1, 2, 3, 4, 5 or 6 and n is 0, 1, 2, 3 or 4.

[0472] R6preferably denotes methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentoxy.

[0473] In formula VI-1-22, R6preferably denotes n-propyl.

[0474] In the compounds of the formula VI-1-4, (O) preferably denotes -O-. The compounds of the formula VI-2 are preferably selected from the formulae VI-2-1 to VI-2-15, very preferably of the formula VI-2-1:

[0475]

[0476]

[0477]

[0478] in which R6denotes a straight-chain alkyl or alkoxy radical having 1 to 6 C atoms, (O) denotes -O- or a single bond, and m is 0, 1, 2, 3, 4, 5 or 6.

[0479] R6preferably denotes methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentoxy.

[0480] Preferred examples of compounds of the formula VI in which n6 is 0 are the following:

[0481]

[0482] in which in which R6denotes a straight-chain alkyl or alkoxy radical having 1 to 6 C atoms, (O) denotes -O- or a single bond, and m is 0, 1, 2, 3, 4, 5 or 6.

[0483] R6preferably denotes methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentoxy.

[0484] In a preferred embodiment of the present invention the medium additionally comprises one or more compounds of the formulae VII-1 to VII-9

[0485]

[0486]

[0487] in which

[0488] R7denotes a straight-chain alkyl or alkoxy radical having 1 to 6 C atoms, or a straight chain alkenyl radical having 2 to 6 C atoms, and

[0489] w is an integer from 1 to 6.

[0490] Preferably, the medium according to the invention comprises one or more compounds of the formula VIII:

[0491]

[0492] in which

[0493] R81and R82, identically or differently, denote H, halogen, CN, SCN, straight chain alkyl or alkoxy having 1 to 15 C atoms, straight chain alkenyl or alkenyloxy having 2 to 15 C atoms or branched alkyl, alkoxy, alkenyl or alkenyloxy having 3 to 15 C atoms, where one or more CH2groups in these radicals may each be replaced, independently of one

[0494]

[0495] -OCF2-, -CH=CH-, by -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen,

[0496] A°, A81, and A82, each, independently of one another, denote phenylene-1,4-diyl, in which one or two CH groups may be replaced by N and one or more H atoms may be replaced by halogen, CN, CH3, CHF2, CH2F, CF3, OCH3, OCHF2or OCF3, cyclohexane-1,4-diyl, in which one or two non-adjacent CH2groups may be replaced, independently of one another, by O and / or S and one or more H atoms may be replaced by F, cyclohexene- 1,4-diyl, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl;

[0497] Z81and Z82, each, independently of one another, denote -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2H4-, -C2F4, -CF2CH2-, -CH2CF2-, -CFHCFH-, -CFHCH2-, -CH2CFH-, -CF2CFH-, -CFHCF2-, -CH=CH-, -CF=CH-, -CH=CF-,

[0498] -CF=CF-, -C≡C- or a single bond;

[0499] n denotes 0, 1, 2 or 3, preferably 0, 1 or 2, very preferably 0 or 1, particularly preferably 0; and

[0500] m denotes 0, 1, 2 or 3, preferably 0, 1 or 2, very preferably 1 or 2, in particular 1.

[0501] A81and A82in formula I preferably denote phenylene-1,4-diyl, which may also be mono- or polysubstituted by F, furthermore cyclohexane-1,4-diyl, cyclohexenylene-1,4-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl, very preferably phenylene-1,4-diyl which may also be mono- or polysubstituted by F, or cyclohexane-1,4-diyl.

[0502] The one or more compounds of the formula VIII are preferably contained in the medium in a total concentration in the range of from 3% to 30%. Z81and Z82in formula VIII preferably denote -CF2O-, -OCF2- or a single bond, very preferably a single bond.

[0503] A81and A82in formula VIII particularly preferably denote

[0504]

[0505]

[0506] in which L denotes halogen, CF3or CN, preferably F.

[0507] Preference is furthermore given to compounds of the formula VIII in which R81and R82each, independently of one another, denote H, F, or alkyl, alkoxy, alkenyl or alkynyl having 1 to 8, preferably 1 to 5, C atoms, each of which is optionally substituted by halogen, in particular by F.

[0508] R81and R82preferably denote H, optionally fluorinated alkyl or alkoxy having 1 to 7 C atoms, optionally fluorinated alkenyl or alkynyl having 2 to 7 C atoms, optionally fluorinated cycloalkyl having 3 to 12 C atoms.

[0509] Preferably, at least one of R81and R82is not H, particularly preferably both of R81and R82are not H. R81is very particularly preferably alkyl. R82is furthermore preferably H, alkyl or fluorine. Very particularly preferably, R81is alkyl and R82is H or alkyl. R81, R82each, independently of one another, very particularly preferably denote unbranched alkyl having 1 to 5 C atoms. If R81and R82denote substituted alkyl, alkoxy, alkenyl or alkynyl, the total number of C atoms in the two groups R81and R82is preferably less than 10.

[0510] Preferred compounds of the formula VIII are selected from the compounds of the formula Villa

[0511]

[0512] Villa

[0513] in which R1and R2, identically or differently, denote straight chain alkyl having 1 to 15 C atoms, straight chain alkenyl having 2 to 15 C atoms or branched alkyl, or alkenyl having 3 to 15 C atoms, where one or more CH2groups in these radicals may each be replaced,

[0514] independently of one another,

[0515]

[0516] ,

[0517]

[0518] ,, and in which one or more H atoms may be replaced by fluorine, preferably both of R1and R2denote straight chain alkyl having 1 to 6 C atoms.

[0519] Very preferred compounds of the formula Villa are selected from the compounds of the formulae VIIIa-1 to VIIIa-35:

[0520]

[0521]

[0522]

[0523]

[0524]

[0525] in which v is an integer from 1 to 6.

[0526] Further preferred compounds of the formula VIII are selected from the following subformulae:

[0527]

[0528]

[0529] in which R81, R82and L have the meanings indicated above, L preferably denotes F, and r, s and t independently are 0, 1, 2, 3, or 4. r preferably is 1 or 2, very preferably 2 and s and t independently are preferably 0 or 1, very preferably 0. R81and R82in particular independently denote n-alkyl having 1 to 5 C atoms.

[0530] In a first very preferred embodiment, the compounds of the formulae VIII-1 to VIII-6 are selected from the compounds of the formula VIII-1a to VIII-6a, in particular of the formula VIII-3a:

[0531]

[0532]

[0533] in which R81, R82, r and s have the meanings defined above.

[0534] In a second very preferred embodiment, the compounds of the formulae VIII-1 to VIII-6 are selected from the compounds of the formula VIII-1b to VIII-6b, in particular of the formula I3-b:

[0535]

[0536]

[0537] in which R81, R82, L, r and s have the meanings defined above.

[0538] In a third very preferred embodiment, the compounds of the formulae VIII-1 to VIII-6 are selected from the compounds of the formula VIII-1c to VIII-6c, in particular of the formula I3-c:

[0539]

[0540] in which R81, R82, L, r and s have the meanings defined above. In a fourth very preferred embodiment, the compounds of the formulae VIII-1 to VIII-6 are selected from the compounds of the formula VIII-1d to VIII-6d, in particular of the formula VIII-3d:

[0541]

[0542] in which R81, R82, L, r and s have the meanings defined above.

[0543] In a particularly preferred embodiment, the medium according to the invention comprises one or more compounds selected from the group of the formulae VIII-1 a to Vlll-6a and one or more compounds selected from the group of the formulae VIII-1 b to Vlll-6b.

[0544] Very particularly preferably the medium comprises one or more compounds selected from the group of compounds of the formulae VI I l-3a, VI I l-3b, VI I l-3c and VI I l-3d:

[0545]

[0546] in which R81, R82, L and r have the meanings defined above and preferably r is 0.

[0547] Most preferred compounds of formula VIII-3a to VIII-3c include, in particular, one or more of the following:

[0548]

[0549]

[0550]

[0551] - iz U -

[0552]

[0553] Alternatively, or additionally, the following compounds of formula VI I l-3a to VI I l-3c can be used:

[0554]

[0555]

[0556]

[0557] VIII-3C-14

[0558]

[0559] In a preferred embodiment, the medium comprises one or more compounds of the formula IX

[0560]

[0561] in which

[0562] R1and R2, identically or differently, denote H, halogen, straight chain alkyl or alkoxy having 1 to 15 C atoms, straight chain alkenyl or alkenyloxy having 2 to 15 C atoms or branched alkyl, alkoxy, alkenyl or alkenyloxy each having 3 to 15 C atoms, where one or more CH2groups in these radicals may each be replaced, independently of one another,

[0563]

[0564] -OCF2-, -CH=CH-, by -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, L11and L12, each, independently of one another, denote F, Cl, CF3 or CHF2,

[0565] L13and L14, each, independently of one another, denote H, F, Cl, CF3 or CHF2,

[0566] Y1denotes H, F, Cl, CF3, CHF2or CH3, preferably H or CH3, and

[0567] n is 0 or 1.

[0568] The one or more compounds of the formula IX are preferably contained in the medium in a total concentration in the range of from 1% to 20%.

[0569] Preference is given to LC media comprising the compounds of formula IX in which n is 0, Y denotes H or CH3, more preferably H, and L11and L12denote F.

[0570] Very preferred compounds of the formula IX are selected from the compounds of the formulae IX- 1 to IX-35

[0571]

[0572]

[0573]

[0574]

[0575]

[0576] Further preferred embodiments are listed below: a) Liquid-crystalline medium comprising at least one compound of the formulae Z-1 to Z-8, preferably of the formulae Z-2, Z-4 and Z-6, very preferably Z-4

[0577]

[0578] in which Rzhas the meaning of R2Aindicated above and preferably denotes alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms,

[0579] (O) denotes O or a single bond and alkyl denotes alkyl having 1 to 7 C atoms.

[0580] The least one compound of the formulae Z-1 to Z-8 are preferably contained in the medium in a total concentration in the range of from 2% to 20%.

[0581] b) Preferred liquid-crystalline media according to the invention comprise one or more compounds which contain a tetrahydronaphthyl or naphthyl unit, such as, for example, selected from the compounds of the formulae N-1 to N-5,

[0582]

[0583] in which R1Nand R2Neach, independently of one another, have the meanings indicated for R2A, preferably denote straight-chain alkyl, straight-chain alkoxy or straight-chain alkenyl, and Z1and Z2each, independently of one another,

[0584] denote -C2H4-, -CH=CH-, -(CH2)4-, -(CH2)3O-, -O(CH2)3-, -CH=CHCH2CH2-, -CH2CH2CH= CH-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CF=CH-, -CH=CF-, -CF2O-, -OCF2-, -CH2- or a single bond.

[0585] The one or more compounds of the formulae N-1 to N-5 are preferably contained in the medium in a total concentration in the range of from 2% to 20%.

[0586] c) Preferred mixtures comprise one or more compounds selected from the group of the difluorodibenzochroman compounds of the formula BC, chromans of the formula CR, and fluorinated phenanthrenes of the formulae PH-1 and PH-2,

[0587]

[0588] in which RB1, RB2, RCR1, RCR2, RP1, RP2each, independently of one another, have the meaning of R31of formula III, preferably alkyl or alkoxy having 1 to 6 C atoms, and c is 0, 1 or 2.

[0589] The one or more compounds selected from the group of the compounds of the formula BC, CR, PH-1 and PH-2, are preferably contained in the medium in a total concentration in the range of from 2% to 20%. Particularly preferred compounds of the formulae BC, CR and PH-1 are the compounds BC-1 to BC-7, CR-1 to CR-5, and BP-1 to BP-7

[0590]

[0591]

[0592]

[0593] in which

[0594] alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1 to 6 C atoms, and

[0595] alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2 to 6 C atoms.

[0596] More preference is given to mixtures comprising one, two or three compounds of the formula BC-2, BC-3, BP-2 and / or BP-3, very preferably BP-2 and / or BP-3, in particular BP-3.

[0597] d) Preferred mixtures comprise one or more indane compounds of the formula In,

[0598]

[0599] in which

[0600] R11, R12, and R13each, independently of one another, denote a straight-chain alkyl, alkoxy, alkoxyalkyl or alkenyl radical having 1 to 6 C atoms,

[0601] R12and R13alternatively denote halogen, preferably F,

[0602] denotes

[0603]

[0604]

[0605] i denotes 0, 1 or 2.

[0606] The one or more compounds of the formula In are preferably contained in the medium in a total concentration in the range of from 2% to 20%.

[0607] Preferred compounds of the formula In are the compounds of the formulae In-1 to In-16 indicated below:

[0608]

[0609]

[0610]

[0611] Particular preference is given to the compounds of the formulae ln-1, ln-2, ln-3 and ln-4.

[0612]

[0613]

[0614] in which

[0615] R, R1and R2each, independently of one another, have the meanings indicated for R2Ain formula IIA above, and alkyl denotes an alkyl radical having 1 to 6 C atoms. The parameter s denotes 1 or 2.

[0616] The compounds of the formulae L-1 to L-9 are preferably employed in concentrations of 5 to 15 % by weight, in particular 5 to 12 % by weight and very particularly preferably 8 to 10 % by weight.

[0617] The one or more compounds of the formula L1- to L-11 are preferably contained in the medium in a total concentration in the range of from 2% to 20%.

[0618] f) Preferred mixtures additionally comprise one or more compounds of formula IIA-Y

[0619]

[0620] in which R11and R12have one of the meanings given for R2Ain formula IIA above, and L1and L2, identically or differently, denote F or Cl.

[0621] The one or more compounds of the formula IIA-Y are preferably contained in the medium in a total concentration in the range of from 0.5% to 10%.

[0622] Preferred compounds of the formula IIA-Y are selected from the group consisting of the following sub-formulae

[0623]

[0624]

[0625] Alkenyl- IIA-Y10

[0626]

[0627] 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 straightchain alkenyl radical having 2-6 C atoms, and O denotes an oxygen atom or a single bond. Alkenyl and Alkenyl* preferably denote CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0628] Particularly preferred compounds of the formula IIA-Y are selected from the group consisting of following sub-formulae:

[0629] Alkoxy IIA-Y6a

[0630]

[0631] Alkoxy IIA-Y6b

[0632]

[0633] in which Alkoxy and Alkoxy* have the meanings defined above and preferably denote methoxy, ethoxy, n-propyloxy, n-butyloxy or n-pentyloxy, very preferably both butoxy. in which

[0634] RSTdenotes H, an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH2groups in these radicals may each be replaced, independently of one

[0635]

[0636] -O-CO- in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, , on each occurrence, identically or differently, denotes

[0637]

[0638]

[0639] p denotes 0, 1 or 2,

[0640] q denotes 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0641] The compounds of the formulae S-1 to S-15 are preferably each present in the liquid-crystal mixtures according to the invention in amounts of 0.005 – 0.5%, based on the mixture.

[0642] If the mixtures according to the invention comprise two or more compounds from the group of the compounds of the formulae S-1 to S-15, the concentration correspondingly increases to 0.01 - 1% in the case of two compounds, based on the mixtures.

[0643] However, the total proportion of the compounds of the formulae ST and S-1 to S-15, based on the mixture according to the invention, should not exceed 2%.

[0644] The liquid crystal medium according to the invention, herein also referred to as liquid crystal host mixture, is suitable for the use in polymer stabilised displays. To this end, the medium according to the invention optionally comprises one or more polymerisable compounds of formula P

[0645] P-Sp-A1-(Z1-A2)z-R P

[0646] in which independently of each other and on each occurrence identically or differently, P denotes a polymerisable group,

[0647] Sp denotes a spacer group or a single bond,

[0648] A1, A2denote 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,

[0649] Z1denotes -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -OCH2-, -CH2O-, -SCH2-, - CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -(CH2)ni-, -CF2CH2-, -CH2CF2-,

[0650] -(CF2)ni-, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-CO-O-,

[0651] -O-CO-CH=CH-, -CH2-CH2-CO-O-, -O-CO-CH2-CH2-, -CR°R00-, or a single bond, R°, R00denote H or alkyl having 1 to 12 C atoms,

[0652] R denotes H, L, or P-Sp-,

[0653] L denotes F, Cl, -CN, P-Sp- or straight chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a manner that O- and / or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by P-Sp-, F or Cl,

[0654] z is 0, 1, 2 or 3, and

[0655] n1 is 1, 2, 3 or 4.

[0656] The term "reliability" as used herein means the quality of the performance of the display during time and with different stress loads, such as light load, temperature, humidity, voltage, and comprises display effects such as image sticking (area and line image sticking), mura, yogore etc. which are known to the skilled person in the field of LC displays. As a standard parameter for categorising the reliability usually the voltage holding ration (VHR) value is used, which is a measure for maintaining a constant electrical voltage in a test display. Among other factors, a high VHR is a prerequisite for a high reliability of the LC medium.

[0657] Unless indicated otherwise, the term "PSA" is used hereinafter when referring to displays of the polymer sustained alignment type in general, and the term "PS" is used when referring to specific display modes, like PS-VA, PS-TN and the like.

[0658] 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.

[0659] 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.

[0660] 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".

[0661] Unless stated otherwise, the term "polymerisable compound" as used herein will be understood to mean a polymerisable monomeric compound.

[0662] 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".

[0663] 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.

[0664] 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.

[0665] As used herein, the terms “optically active” and “chiral” are synonyms for materials that are able to induce a helical pitch in a nematic host material, also referred to as “chiral dopants”.

[0666] The term "spacer group", above and below 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.

[0667] 2004, 116, 6340-6368. As used herein, the terms "spacer group" or "spacer" mean a flexible group, for example an alkylene group, which connects a mesogenic group and a polymerisable group(s) in a polymerisable mesogenic compound.

[0668] Likewise, in the compounds of formula la and lb, a spacer group connects a central hydrocarbon group with a photoactive, stabilising hindered amine functional group.

[0669] Above and below,

[0670]

[0671] denotes a trans- 1,4-cyclohexylene ring.

[0672] In a group

[0673]

[0674] the single bond shown between the two ring atoms can be attached to any free position of the benzene ring.

[0675] Above and below "organic group" denotes a carbon or hydrocarbon group.

[0676] "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.

[0677] "Halogen" denotes F, Cl, Br or I, preferably F or Cl.

[0678] -CO-, -C(=O)- and -C(O)- denote a carbonyl group, i.e

[0679]

[0680] 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.

[0681] The terms "alkyl", "aryl", "heteroaryl", etc., also encompass polyvalent groups, for example alkylene, arylene, heteroarylene, etc.

[0682] 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. 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.

[0683] Further preferred carbon and hydrocarbon groups are C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C3-C20 allyl, C4-C20 alkyldienyl, C4-C20 polyenyl, C6-C20 cycloalkyl, C4-C15 cycloalkenyl, C6-C30 aryl, C6-C30 alkylaryl, C6-C30 arylalkyl, C6-C30 alkylaryloxy, C6-C30 arylalkyloxy, C2-C30 heteroaryl, C2-C30 heteroaryloxy.

[0684] Particular preference is given to C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C6-C25 aryl and C2-C25 heteroaryl.

[0685] 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 CH2 groups may each be replaced, independently of one another, by -C(RX)=C(RX)-, -C≡-, -N(RX)-, -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.

[0686] Rxpreferably denotes H, F, Cl, CN, a straight-chain, branched or cyclic alkyl chain having 1 to 25 C atoms, in which, in addition, one or more non-adjacent C atoms may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- and in which one or more H atoms may be replaced by F or Cl, or denotes an optionally substituted aryl or aryloxy group with 6 to 30 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group with 2 to 30 C atoms.

[0687] Preferred alkyl groups are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, cyclopentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, dodecanyl, trifluoromethyl, perfluoro-n-butyl, 2,2,2-trifluoroethyl, perfluorooctyl, perfluorohexyl, etc.

[0688] Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl, etc.

[0689] Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, octynyl, etc.

[0690] Preferred alkoxy groups are, for example, methoxy, ethoxy, 2-methoxyethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, 2-methylbutoxy, n-pentoxy, n-hexoxy, n-heptoxy, n-octoxy, n-nonoxy, n-decoxy, n-undecoxy, n-dodecoxy, etc.

[0691] Preferred amino groups are, for example, dimethylamino, methylamino, methylphenylamino, phenylamino, etc.

[0692] 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.

[0693] 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.

[0694] 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.

[0695] 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,

[0696] 1.2.4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1.2.5-thiadiazole, 1,3,4-thiadiazole, 6-membered rings, such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1, 2,3,4-tetrazine, 1,2,3,5-tetrazine, or condensed groups, such as indole, isoindole, indolizine, indazole, benzimidazole, benzotriazole, purine, naphthimidazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole, quinoxalinimidazole, benzoxazole, naphthoxazole, anthroxazole, phenanthroxazole, isoxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, benzoisoquinoline, acridine, phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline, phenanthridine, phenanthroline, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene, dibenzothiophene, benzothiophene, benzothiadiazothiophene, or combinations of these groups.

[0697] 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.

[0698] 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.

[0699] 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 CH2 groups may be replaced by -O- and / or -S-.

[0700] Preferred alicyclic and heterocyclic groups are, for example, 5-membered groups, such as cyclopentane, tetrahydrofuran, tetrahydrothiophene, 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.

[0701] 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.

[0702] Preferred substituents, hereinafter also referred to as "Ls", are, for example, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(RX)2, -C(=O)Y1,

[0703] -C(=O)RX, -N(RX)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,

[0704] wherein Rxdenotes H, F, Cl, CN, or straight chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacent CH2-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

[0705] Y1denotes halogen.

[0706] "Substituted silyl or aryl" preferably means substituted by halogen, -CN, R°, -OR0, -CO-R°, -CO-O-R0, -O-CO-R0or -O-CO-O-R0, wherein R° denotes H or alkyl with 1 to 20 C atoms.

[0707] Particularly preferred substituents L are, for example, F, Cl, CN, NO2, CH3, C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5, furthermore phenyl.

[0708] (L)r

[0709] A1and A2very preferably denote

[0710]

[0711] jn which L has one of the meanings indicated above and r denotes 0, 1, 2, 3 or 4, in particular

[0712]

[0713] 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.

[0714] Preferred groups P are selected from the group consisting of

[0715]

[0716] CO-NH-, CH2=CH-(COO)ki-Phe-(O)k2-, CH2=CH-(CO)ki-Phe-(O)k2-,

[0717] Phe-CH=CH-, HOOC-, OCN- and WWSi- in which W1denotes H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH3, W2and W3each, independently of one another, denote H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W4, W5and W6each, independently of one another, denote Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W7and W8each, 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-, ki, k2 and k3each, independently of one another, denote 0 or 1, ka preferably denotes 1, and k4 denotes an integer from 1 to 10.

[0718] Very preferred groups P are selected from the group consisting of

[0719]

[0720] CH2=CH-(COO)ki-Phe-(O)k2-, CH2=CH-(CO)ki-Phe-(O)k2-, Phe-CH=CH- and WWSi-, in which W1denotes H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH3, W2and W3each, independently of one another, denote H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W4, W5and W6each, independently of one another, denote Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W7and W8each, independently of one another, denote H, Cl or alkyl having 1 to 5 C atoms, Phe denotes 1,4-phenylene, ki, k2and k3each, independently of one another, denote 0 or 1, k3preferably denotes 1, and k4denotes an integer from 1 to 10.

[0721] Very particularly preferred groups P are selected from the group consisting of CH2=CW1- CO-O-, in particular CH2=CH-CO-O-, CH2=C(CH3)-CO-O- and CH2=CF-CO-O-,

[0722] O

[0723] 2 ' ' furthermore CH2=CH-O-, (CH2=CH)2CH-O-CO-, (CH2=CH)2CH-O-, W HC — CH- and

[0724]

[0725] 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. If the spacer group Sp is different from a single bond, it is preferably of the formula Sp"-X", so that the respective radical P-Sp- conforms to the formula R-Sp"-X"-, wherein

[0726] Sp" denotes linear or branched alkylene having 1 to 20, preferably 1 to 12, C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN and in which, in addition, one or more non-adjacent CH2groups may each be replaced, independently of one another, by -O-, -S-,

[0727] -NH-, -N(R°)-, -Si(R°R00)-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -S-CO-,

[0728] -CO-S-, -N(R°°)-CO-O-, -O-CO-N(R°)-, -N(R°)-CO-N(R00)-, -CH=CH- or -C≡C- in such a way that O and / or S atoms are not linked directly to one another,

[0729] X" denotes -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CO-N(R0)-, -N(R°)-CO-, -N(R°)-CO-N(R00)-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-,

[0730] -SCF2-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CR0-, -CY2=CY3-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH- or a single bond,

[0731] R° and R°°, each, independently of one another, denote H or alkyl having 1 to 20 C atoms, and

[0732] Y2and Y3each, independently of one another, denote H, F, Cl or CN.

[0733] X" is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR0-,

[0734] -NR°-CO-, -NR°-CO-NR°°- or a single bond.

[0735] Typical spacer groups Sp and -Sp"-X"- are, for example, -(CH2)PI-, -(CH2)PI-O-, -(CH2)pi-O-CO-, -(CH2)p1-CO-O-, -(CH2)p1-O-CO-O-, -(CH2CH2O)qi-CH2CH2-, -CH2CH2-S-CH2CH2-, -CH2CH2-NH-CH2CH2- or -(SiR°R°°-O)pi-, in which p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R° and R°° have the meanings indicated above.

[0736] Particularly preferred groups Sp and -Sp"-X"- are -(CH2)PI-, -(CH2)PI-O-, -(CH2)PI-O-CO-, -(CH2)PI-CO-O-, -(CH2)PI-O-CO-O-, in which p1 and q1 have the meanings indicated above.

[0737] Particularly preferred groups Sp" are, in each case straight-chain, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethylene-N-methyliminoethylene, 1 -methylalkylene, ethenylene, propenylene and butenylene.

[0738] In a preferred embodiment of the invention the compounds of formula P and its subformulae contain a spacer group Sp that is substituted by one or more polymerisable groups P, so that the group Sp-P corresponds to Sp(P)s, with s being >2 (branched polymerisable groups).

[0739] Preferred compounds of formula P according to this preferred embodiment are those wherein s is 2, i.e., compounds which contain a group Sp(P)2. Very preferred compounds of formula P according to this preferred embodiment contain a group selected from the following formulae:

[0740] -X-alkyl-CHPP S1

[0741] -X-alkyl-CH((CH2)aaP)((CH2)bbP) S2

[0742] -X-N((CH2)aaP)((CH2)bbP) S3

[0743] -X-alkyl-CHP-CH2-CH2P S4

[0744] -X-alkyl-C(CH2P)(CH2P)-C aaH2aa+1 S5

[0745] -X-alkyl-CHP-CH2P S6

[0746] -X-alkyl-CPP-C aaH2aa+1 S7

[0747] -X-alkyl-CHPCHP-CaaH2aa+1S8

[0748] in which P is as defined in formula P,

[0749] alkyl denotes a single bond or straight-chain or branched alkylene having 1 to 12 C atoms which is unsubstituted or mono- or polysubstituted by F, Cl or CN and in which one or more non-adjacent CH2groups may each, independently of one another, be replaced by -C(R°)=C(R0)-, -C≡C-, -N(R0)-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not linked directly to one another, where R° has the meaning indicated above,

[0750] aa and bb each, independently of one another, denote 0, 1, 2, 3, 4, 5 or 6,

[0751] X has one of the meanings indicated forX", and is preferably O, CO, SO2, O-CO-, CO-O or a single bond.

[0752] Preferred spacer groups Sp(P)2are selected from formulae S1, S2 and S3. Very preferred spacer groups Sp(P)2 are selected from the following sub-formulae:

[0753] -CHPP S1a

[0754] -O-CHPP S1b

[0755] -CH2-CHPP S1c

[0756] -OCH2-CHPP S1d

[0757] -CH(CH2-P)(CH2-P) S2a

[0758] -OCH(CH2-P)(CH2-P) S2b

[0759] -CH2-CH(CH2-P)(CH2-P) S2C

[0760] -OCH2-CH(CH2-P)(CH2-P) S2d

[0761] -CO-NH((CH2)2P)((CH2)2P) S3a

[0762] In the compounds of formula P and its sub-formulae as described above and below, P is preferably selected from the group consisting of vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, most preferably from acrylate and methacrylate.

[0763] Further preferred are compounds of formula P and its sub-formulae as described above and below, wherein all polymerisable groups P that are present in the compound have the same meaning, and very preferably denote acrylate or methacrylate, most preferably methacrylate.

[0764] In the compounds of formula P and its sub-formulae as described above and below, R preferably denotes P-Sp-.

[0765] Further preferred are compounds of formula P and its sub-formulae as described above and below, wherein Sp denotes a single bond or-(CH2)Pi-, -O-(CH2)PI-, -O-CO-(CH2)PI, or -CO-O-(CH2)PI, wherein p1 is 2, 3, 4, 5 or 6, and, if Sp is -O-(CH2)PI-, -O-CO-(CH2)PI or-CO-O-(CH2)PI the O-atom or CO-group, respectively, is linked to the benzene ring.

[0766] Further preferred are compounds of formula P and its sub-formulae as described above and below, wherein at least one group Sp is a single bond.

[0767] Further preferred are compounds of formula P and its sub-formulae as described above and below, wherein at least one group Sp is different from a single bond, and is preferably selected from -(CH2)PI-, -O-(CH2)PI-, -O-CO-(CH2)PI, or -CO-O-(CH2)PI, wherein p1 is 2, 3, 4, 5 or 6, and, if Sp is -O-(CH2)PI-, -O-CO-(CH2)PI or -CO-O-(CH2)PI the O-atom or CO-group, respectively, is linked to the benzene ring.

[0768] Very preferred groups -A1-(Z-A2)z- in formula P are selected from the following formulae

[0769]

[0770] wherein at least one benzene ring is substituted by at last one group L and the benzene rings are optionally further substituted by one or more groups L or P-Sp-.

[0771] Preferred compounds of formula P and their sub-formulae are selected from the following preferred embodiments, including any combination thereof:

[0772] All groups P in the compound have the same meaning,

[0773] -A1-(Z-A2)z- is selected from formulae A1, A2 and A5,

[0774] the compounds contain exactly two polymerizable groups (represented by the groups P), the compounds contain exactly three polymerizable groups (represented by the groups P),

[0775] P is selected from the group consisting of acrylate, methacrylate and oxetane, very preferably acrylate or methacrylate,

[0776] P is methacrylate,

[0777] all groups Sp are a single bond,

[0778] at least one of the groups Sp is a single bond and at least one of the groups Sp is different from a single bond,

[0779] Sp, when being different from a single bond, is -(CH2)P2-, -(CH2)P2-O-,

[0780] -(CH2)P2-CO-O-, -(CH2)P2-O-CO-, wherein p2 is 2, 3, 4, 5 or 6, and the O-atom or the CO-group, respectively, is connected to the benzene ring,

[0781] Sp is a single bond or denotes -(CH2)P2-, -(CH2)P2-O-, -(CH2)P2-CO-O-, -(CH2)P2-O-CO-, wherein p2 is 2, 3, 4, 5 or 6, and the O-atom or the CO-group, respectively, is connected to the benzene ring,

[0782] R denotes P-Sp-,

[0783] R does not denote or contain a polymerizable group,

[0784] R does not denote or contain a polymerizable group and denotes straight chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacent degroups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a manner that O- and / or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F, Cl or La,

[0785] L or L’ denote F, Cl or CN,

[0786] L is F.

[0787] Suitable and preferred compounds of formula P are selected from the following formulae:

[0788]

[0789] H-d

[0790]

[0791]

[0792]

[0793]

[0794]

[0795]

[0796]

[0797] in which the individual radicals have the following meanings:

[0798] P1, P2and P3each, independently of one another, denote an acrylate or methacrylate group,

[0799] Sp1, Sp2and Sp3each, independently of one another, denote a single bond or a spacer group having one of the meanings indicated above and below for Sp, and particularly preferably denote -(CH2)p1-, -(CH2)p1-O-, -(CH2)p1-CO-O-,

[0800] -(CH2)p1-O-CO- or -(CH2)p1-O-CO-O-, in which p1 is an integer from 1 to 12, where, in addition, one or more of the radicals P1-Sp1-, P2-Sp2- and P3-Sp3- may denote Raa, with the proviso that at least one of the radicals P1-Sp1-, P2-Sp2- and P3-Sp3- present is different from Raa,

[0801] Raadenotes 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 CH2groups may each be replaced, independently of one another, by -C(R°)=C(R00)-, -C≡C-, -N(R°)-,

[0802] -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 P1-Sp1-, 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),

[0803] R°, R°° each, independently of one another and identically or differently on each occurrence, denote H or alkyl having 1 to 12 C atoms,

[0804] Ryand Rzeach, independently of one another, denote H, F, CH3or CF3,

[0805] X1, X2and X3each, independently of one another, denote -CO-O-, -O-CO- or a single bond,

[0806] Z1denotes -O-, -CO-, -C(RyRz)- or -CF2CF2-,

[0807] Z2and Z3each, independently of one another, denote -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -(CH2)n-, where n is 2, 3 or 4,

[0808] L on each occurrence, identically or differently, denotes F, Cl, CN or straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, preferably F,

[0809] L' and L" each, independently of one another, denote H, F or Cl,

[0810] k denotes 0 or 1,

[0811] r denotes 0, 1, 2, 3 or 4,

[0812] s denotes 0, 1, 2 or 3,

[0813] t denotes 0, 1 or 2,

[0814] x denotes 0 or 1.

[0815] Especially preferred are compounds of the formulae P2, P13, P17, P22, P23, P24, P30, P31 and P32.

[0816] Further preferred are trireaktive compounds P15 to P30, in particular P17, P18, P19, P22, P23, P24, P25, P26, P30, P31 and P32.

[0817] In the compounds of formulae P1 to P32 the group

[0818]

[0819]

[0820] wherein L on each occurrence, identically or differently, has one of the meanings given above or below, and is preferably F, Cl, CN, NO2, CH3, C2H5, C(CH3)3, CH(CH3)2, CH2CH(CH3)C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5 or P-Sp-, very preferably F, Cl, CN, CH3, C2H5, OCH3, COCH3, OCF3or P-Sp-, more preferably F, Cl, CH3, OCH3, COCH3Oder OCF3, especially F or CH3.

[0821] Very particularly preferred compounds of the formula P are selected from Table E below.

[0822] 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.

[0823] 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.

[0824] A preferred PSA type LC display of the present invention comprises:

[0825] 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,

[0826] 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,

[0827] an LC layer disposed between the first and second substrates and including an LC medium comprising a polymerisable component comprising one or more compounds of formula R and a liquid crystal host including as described above and below, wherein the polymerisable component may also be polymerised.

[0828] 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.

[0829] 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.

[0830] 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.

[0831] 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.

[0832] 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.

[0833] 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").

[0834] 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.

[0835] 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.

[0836] 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.

[0837] 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 P), is preferably 10-500,000 ppm, particularly preferably 50-50,000 ppm.

[0838] The polymerisable compounds of formula P 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,

[0839] - the polymerisable medium is exposed to UV light in the display generated by an energysaving 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 300-380nm, 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.

[0840] - 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 340nm or more, to avoid short UV light exposure in the PS-VA process.

[0841] 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.

[0842] 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,

[0843] - the polymerisable LC medium is exposed to UV light generated by a UV lamp having an intensity of from 0.5 mW / cm2to 10 mW / cm2in the wavelength range from 300-380nm, preferably used in the UV2 step, and optionally also in the UV1 step,

[0844] - the polymerisable LC medium is exposed to UV light having a wavelength of 340 nm or more, and preferably 400 nm or less.

[0845] 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 300-400nm is desired, UV exposure can be carried out using a wide band pass filter being substantially transmissive for wavelengths 300nm < λ < 400nm. 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. "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.

[0846] 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.

[0847] UV radiation energy is in general from 6 to 100 J, depending on the production process conditions.

[0848] Preferably the LC medium according to the present invention essentially consist of a polymerisable component P) comprising or one or more polymerisable compounds of formula P, and an LC host mixture, and an optically active component comprising one or more chiral dopants, 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, 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.

[0849] Particular preference is given to LC media comprising one, two or three polymerisable compounds of formula P.

[0850] Preferably the proportion of compounds of formula P in the LC medium is from >0 to < 5%, very preferably from >0 to < 1%, most preferably from 0.01 to 0.5%.

[0851] In a preferred embodiment, the medium according to the invention preferably comprises one or more compounds of formula S in a total concentration in the range of from 10 ppm to 2000 ppm, more preferably from 100 ppm to 1000 ppm, still more preferably from 150 ppm to 500 ppm, very preferably from 200 ppm to 400 ppm and in particular from 250 to 300 ppm. The medium according to the invention preferably has negative dielectric anisotropy.

[0852] The liquid crystal mixture according to the invention is nematic, preferably at a temperature of -20°C or less, preferably at -30°C or less, very preferably at -40°C or less.

[0853] It is advantageous for the liquid-crystalline medium according to the invention to preferably have a nematic phase from < -20°C to > 74°C, particularly preferably from < -30°C to > 80°C, very particularly preferably from < -40°C to > 90°C.

[0854] The expression "have a nematic phase" herein means on the one hand that no smectic phase and no crystallisation are observed at low temperatures at the corresponding temperature and on the other hand that clearing (phase transition to the isotropic phase) still does not occur on heating from the nematic phase. The investigation at low temperatures is carried out in a flow viscometer at the corresponding temperature and checked by storage in test cells having a layer thickness corresponding to the electro-optical use for at least 100 hours. If the storage stability at a temperature of -20°C in a corresponding test cell is 1000 h or more, the medium is referred to as stable at this temperature. At temperatures of -30°C and -40°C, the corresponding times are 500 h and 250 h respectively. At high temperatures, the clearing point is measured by conventional methods in capillaries.

[0855] In a preferred embodiment, the medium according to the invention has a clearing temperature of 74°C or more, preferably of 80°C or more, more preferably of 82°C or more and in particular of 83°C or more.

[0856] In an embodiment, the liquid-crystal mixture according to the invention has a dielectric anisotropy Δε of 2.0 to 15.0, more preferably of 3 to 12.0, very preferably 3.5 to 10 and in particular 4.0 to 8.0.

[0857] In an embodiment, the liquid-crystal mixture according to the invention has a dielectric anisotropy Δε of -2.0 to -6.0, more preferably of -2.2 to -5.0, very preferably -2.4 to -4.3 and in particular -3.0 to -4.0.

[0858] The birefringence Δn of the liquid-crystalline media according to the invention is preferably from 0.080 to 0.140, very preferably from 0.090 to 0.135, in particular from 0.091 to 0.132. In a preferred embodiment of the present invention the medium has a birefringence of from 0.090 to 0.115, very preferably from 0.095 to 0.110, in particular from 0.100 to 0.113.

[0859] In a preferred embodiment of the present invention the medium has a birefringence of from 0.110 to 0.130, very preferably from 0.119 to 0.128, in particular from 0.120 to 0.123.

[0860] In a preferred embodiment of the present invention the medium has a birefringence of from 0.120 to 0.140, very preferably from 0.125 to 0.135, in particular from 0.129 to 0.132.

[0861] In a preferred embodiment of the present invention, the medium has a birefringence in the range of from 0.080 to 0.110, more preferably from 0.085 to 0.105, very preferably from 0.087 to 0.100 and in particular from 0.089 to 0.095.

[0862] The rotational viscosity γ1 at 20°C is preferably in the range of from 50 to 250 mPas, more preferably from 70 to 140 mPa s.

[0863] Further preferred embodiments, taken alone or in combination with one another are the following.

[0864] In an embodiment the medium has positive dielectric anisotropy and preferably comprises - one or more compounds of formula II, preferably of formula 11-1 and optionally 11-3, more preferably of the sub-formulae 11-1 a and / or ll-1f and / or ll-1g and / or 11-1 h and / or ll-3a and / or I l-3d, in a total concentration in the range of from 5 % to 35 %, preferably from 6 % to 32 %, particularly preferably from 8 % to 28 %;

[0865] and / or

[0866] - one or more compounds of formula 11-1, more preferably of the sub-formulae 11-1 a and / or ll-1f and / or ll-1g and / or ll-1h, in particular of formula ll-1a-1 and ll-1f-1, or of formula ll-1a-1 and ll-1f-1 and ll-1h-1, or of formula ll-1f-1 and ll-1g-1 and ll-1h-1, preferably in a total concentration in the range of from 2 % to 22 %, preferably from 3 % to 19 %, particularly preferably from 4 % to 17 %;

[0867] and / or

[0868] one or more compounds of formula of 11-1 f- 1, in a total concentration in the range of from 0.3 % to 8 %, preferably 0.5% to 6%, particularly preferably 1% to 5%; and / or

[0869] one or more compounds of formula of 11-1 g-1, in a total concentration in the range of from 1 % to 15 %, preferably 2% to 12%, particularly preferably 3% to 10%;

[0870] and / or

[0871] one or more compounds of formula of 11-1 a-1, in a total concentration in the range of from 0.5 % to 15 %, preferably 1% to 10%;

[0872] and / or

[0873] - one or more compounds of formula III in a total concentration in the range of from 1% to 25%, preferably from 2% to 20%, more preferably from 5% to 15%, preferably selected from the group of compounds of formula HI-2, more preferably of the formulae II l-2c and / or 11 l-2d, and / or I ll-2g and / or I ll-2h and / or I ll-2i and / or 11 l-2k and / or III-2I and / or 11 l-2m, very preferably of the formulae lll-2c-3 and / or lll-2d-1, and / or lll-2g-2 and / or lll-2h-3, in particular 11 l-2k-6 and / or 11 l-2h-3;

[0874] and / or

[0875] one or more compounds of formula of 11 l-2k-6 in a total concentration in the range of from 0.5 % to 5 %, preferably 1% to 4%;

[0876] and / or

[0877] one or more compounds of formula of 11 l-2h-3 in a total concentration in the range of from 0.5 % to 5 %, preferably 1% to 4%;

[0878] and / or

[0879] one or more compounds of the formula CL, more preferably of the formula CL-2 and / or CL-3, very preferably selected form the compounds CLP-n-T, CLP-V-m, CLP-V-Om, CLP-n-m, and CLP-n-Om, in which n and m independently are 1, 2, 3, 4 or 5, in particular CLP-n-T, preferably in a total concentration in the range of from 1% to 12%, more preferably from 2% to 10% and very preferably from 5% to 9%,

[0880] and / or

[0881] one or more compounds of formula VI, preferably of the formula VI-1-20 and / or VI- 1-21, preferably in a total concentration in the range of from 1% to 15%, preferably from 2% to 13%, in particular from 3% to 11%; and / or

[0882] - one or more compounds of formula IV, preferably of the formula I V-3, in a total concentration in the range of from 20 % to 70%, more preferably 30% to 65%, very preferably 40% to 60%, preferably selected from the compounds of the formulae IV-3-1 to IV-3-6, in particular selected from the compounds of formula IV-3-1, IV-3-2, IV-3-4 and IV-3-6;

[0883] and / or

[0884] - 0.5% to 8%, preferably 1% to 6% of the compound IV-3-6 (CC-3-2V1) or IV-3-4 (CC-4-V1);

[0885] and / or

[0886] - one or more compounds of formula IVa, preferably of formula IVa-2, preferably in a total concentration in the range of from 0.1% to 3%, more preferably from 0.2% to 2%;

[0887] and / or

[0888] - one or more compounds of formula IVb, preferably of formula IVb-2, very preferably of formula IVb-2-3, preferably in a total concentration in the range of from 0.2% to 8%, more preferably from 0.5% to 6%, in particular from 1% to 5%;

[0889] and / or

[0890] one or more compounds of formula V, preferably selected from the group consisting of the compounds V-1-1, V-1-6, V-2-1, V-2-2, V-2-3, V-2-4, V-3-5 and V-4-1, preferably in a total concentration in the range of from 5% to 50%, preferably from 10% to 40%, in particular from 15% to 33%;

[0891] and / or

[0892] one or more compounds of formula V-1-1 or V-1-6, preferably selected from the compounds CCC-n-V, CCC-V-V and CVCC-n-m, preferably in a total concentration in the range of from 0.5% to 15%, preferably from 1% to 12%, in particular from 2% to 10%;

[0893] and / or

[0894] one or more compounds of formula V-2-1 and / or V-2-2, preferably CCP-n-m and / or CCP-Vn-m and / or CPP-n-m, very particularly selected from the group consisting of CCP-3-1, CCP-V-1, and CCP-V2-1, preferably in a total concentration in the range of from 8% to 35%, more preferably from 10% to 30%, very preferably from 12% to 28%; In another embodiment the medium has negative dielectric anisotropy and preferably comprises

[0895] - one or more compounds of formula NIIA, preferably NIIA-10 and optionally NIIA-2, more preferably one or more compounds CCY-n-Om and optionally CY-n-Om, in particular selected from CY-3-02, CY-4-02, CY-3-03, CCY-4-02, CCY-3-02, CCY-3-03, CCY-3-01 and CCY-5-02, preferably in a total concentration in the range of from 2% to 35%, more preferably from 5% to 30%, particularly preferably from 7% to 28%;

[0896] - one or more compounds of formula NIIA-10, more preferably one or more compounds CCY-n-Om, in particular CCY-4-02, CCY-3-02, CCY-3-03, CCY-3-O1 and / or CCY-5-02, preferably in a total concentration in the range of from 2% to 25%, more preferably from 5% to 20%, particularly preferably from 7% to 18%;

[0897] - one or more compounds of formula NIIB, preferably NIIB-10, in particular CPY-n-Om, preferably in a total concentration in the range of from 1% to 20%, more preferably from 3 % to 18%, particularly preferably from 5% to 15%,

[0898] - one or more compounds of the formula NIIA-Y, preferably in a total concentration in the range of from 1% to 15%, more preferably from 2% to 12%, very preferably from 3% to 10%;

[0899] - one or more compounds of formula N 11 D, preferably selected from the compounds of the formulae NIID-4 and NIID-10, more preferably NIID-4, very preferably CLY-n-Om, in particular CLY-2-04, CLY-3-02 and / or CLY-3-03, preferably in a total concentration in the range of from 1% to 20%, more preferably from 3 % to 18%,

[0900] and / or

[0901] - one or more compounds of formula NIID-10, preferably CLOY-n-Om, in particular CLOY-3-02, preferably in a total concentration in the range of from 2% to 35%, more preferably, from 4 % to 30%, particularly preferably from 6% to 26%;

[0902] and / or

[0903] - one or more compounds of the formula NIII, preferably of the formula NIII-2 and / or NIII-3, more preferably of the formula NIII-2-6 and / or NIII-3, in particular one or more compounds B(S)-nO-Om and / or COB(S)-n-Om, very particularly B(S)-2O-O4, B(S)-2O-O5, B(S)-2O- 06, B(S)-2O-O1(c5), B(S)-4O-O1(c5), and / or COB(S)-2-O4, preferably in a total concentration in the range of from 1% to 15%, more preferably from 2% to 12% and very preferably from 3% to 10%;

[0904] and / or

[0905] - one or more compounds of the formula NIII and / or PH-1, preferably of the formula NIII-2 and / or BP-3, more preferably of the formula NIII-2-6, in particular selected from B(S)-2O-04, B(S)-2O-O5 and B(S)-2O-O6, preferably in a total concentration in the range of from 1% to 15%, more preferably from 2% to 12% and very preferably from 3% to 10%;

[0906] VI

[0907] and / or

[0908] - one or more compounds of formula IV, preferably in a total concentration in the range of from 25% to 70%, more preferably from 30 % to 60%, particularly preferably from 40% to 55%;

[0909] and / or

[0910] - one or more compounds of the formula IV-1, preferably IV-1-6, preferably in a total concentration in the range of from 1% to 20%, more preferably from 1% to 10% and very preferably from 1% to 8%;

[0911] and / or

[0912] - the compound(s) of the formula CC-3-V1 and / or CC-4-V1, in a total concentration in the range of from 2 to 20%, more preferably from 3% to 15%, particularly preferably from 5% to 10%,

[0913] and / or

[0914] - one or more compounds of the formula IV-3-1, preferably CC-3-V and / or CC-4-V, preferably in a total concentration in the range of from 20% to 60%, more preferably from 25% to 52% and very preferably from 28% to 48%;

[0915] and / or

[0916] - one or more compounds of the formula IVa, more preferably of the formula IVa-2, in particular CP-3-02, in a total concentration in the range of from 0.5% to 8%, more preferably from 1% to 6%, very preferably from 2% to 5%; and / or

[0917] - one or more compounds of the formula V, more preferably selected from the compounds of the formulae V-2-1 and V-2-2, in particular CCP-n-m and / or CCP-Vn-m and / or CPP-n-m, very particularly selected from the group consisting of CCP-3-1, CCP-V-1, CCP-V2-1 and CPP-3-2, preferably in a total concentration in the range of from 1% to 20%, more preferably from 2% to 17%, very preferably from 3% to 14%;

[0918] and / or

[0919] - one or more compounds selected from the compounds of the formulae V-1-1 and V-1-6, in particular CCC-n-m and / or CCC-n-V, very particularly CCC-3-V and / or CCC-V-V, preferably in a total concentration in the range of from 1% to 20%, more preferably from 2% to 17%, very preferably from 3% to 14%;

[0920] and / or

[0921] one or more compounds of the formula CL, more preferably of the formula CL-3, very preferably selected form the compounds CLP-V-m, CLP-V-Om, CLP-n-m, and CLP-n-Om, in which n and m independently are 1, 2, 3, 4 or 5, preferably in a total concentration in the range of from 1% to 12%, more preferably from 2% to 10% and very preferably from 3% to 7%,

[0922] and / or

[0923] less than 10% in total of one or more compounds of the formula V, more preferably less than 5%, very preferably less than 2%, in particular 0%;

[0924] and / or

[0925] one or more compounds of the formula COYOIC-n-m

[0926] and / or

[0927] one or more compounds of the formula COY-n-Om and / or CCOY-n-Om

[0928] and / or

[0929] 0.1% to 3% of the compound PPGU-3-F and / or PPGU-(c5)-F,

[0930] and / or

[0931] 0.1% to 3% of a compound 3-fluoro-4'-alkyl-4-[4-(naphthalen-2-yl)phenyl]-1,1'-biphenyl (PGPNp-n-H:

[0932]

[0933] in which alkyl is methyl, ethyl, n-propyl, n-butyl, n-pentyl or n-hexyl, preferably n- propyl,

[0934] and / or

[0935] 0.1 to 3% of 2-(4-methylphenyl)-6-propylnaphthalene

[0936]

[0937] The liquid-crystal media according to the invention have high values for the voltage holding ratio in liquid-crystal cells.

[0938] In general, liquid-crystal media having a low addressing voltage or threshold voltage exhibit a lower voltage holding ratio than those having a higher addressing voltage or threshold voltage and vice versa.

[0939] As used herein, the term "dielectrically positive compounds" denotes compounds having a Ac > 1.5, the term "dielectrically neutral compounds" denotes those having -1.5 < Ac < 1.5 and the term "dielectrically negative compounds” denotes those having Ac < -1.5. The dielectric anisotropy of the compounds is determined here by dissolving 10 % of the compounds in a liquid-crystalline host and determining the capacitance of the resultant mixture in at least one test cell in each case having a layer thickness of 20 pm with homeotropic and with homogeneous surface alignment at 1 kHz. The measurement voltage is typically 0.5 V to 1.0 V but is always lower than the capacitive threshold of the respective liquid-crystal mixture investigated.

[0940] All temperature values indicated for the present invention are in °C. The mixtures according to the invention are suitable for all VA-TFT applications, such as, for example, VAN, MVA, (S)-PVA, ASV, PSA (polymer sustained VA) and PS-VA (polymer stabilized VA). They are furthermore suitable for IPS (in-plane switching) and FFS (fringe field switching) applications having negative Ac, in particular LIB-FFS.

[0941] It goes without saying for the person skilled in the art that the VA, IPS or FFS mixture according to the invention may also comprise compounds in which, for example, H, N, O, Cl and F have been replaced by the corresponding isotopes.

[0942] The compounds according to the present invention can be synthesized by or in analogy to known methods described in the literature (for example in the standard works such as Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), under reaction conditions which are known and suitable for said reactions. Use may also be made here of variants which are known per se but are not mentioned here. In particular, they can be prepared as described in or in analogy to the following reaction schemes. Further methods for preparing the inventive compounds can be taken from the examples.

[0943] Other mesogenic compounds which are not explicitly mentioned above can optionally and advantageously also be used in the media in accordance with the present invention. Such compounds are known to the person skilled in the art.

[0944] For the present invention and in the following examples, the structures of the liquid-crystal compounds are indicated by means of acronyms, with the transformation into chemical formulae taking place in accordance with Tables A to C below. All radicals CmH2m+1, CnH2n+1, and ClH2l+1or CmH2m-1, CnH2n-1and ClH2l-1are straight-chain alkyl radicals or alkylene radicals, in each case having n, m and I C atoms respectively. Preferably n, m and I are independently of each other 1, 2, 3, 4, 5, 6, or 7. Table A shows the codes for the ring elements of the nuclei of the compound, Table B lists the bridging units, and Table C lists the meanings of the symbols for the left- and right-hand end groups of the molecules. The acronyms are composed of the codes for the ring elements with optional linking groups, followed by a first hyphen and the codes for the left-hand end group, and a second hyphen and the codes for the right-hand end group. Table D shows illustrative structures of compounds together with their respective abbreviations. Table A: Ring elements

[0945]

[0946]

[0947]

[0948]

[0949]

[0950] On the left only in combination On the right only in combination

[0951]

[0952]

[0953] in which n and m are each integers, and the three dots are placeholders for other abbreviations from this table.

[0954] The medium according to the invention preferably comprises one or more compounds of the compounds mentioned in Table D below.

[0955] The following abbreviations are used:

[0956] (n, m, k and I are, independently of one another, each an integer, preferably 1 to 9 preferably 1 to 7, k and I possibly may be also 0 and preferably are 0 to 4, more preferably 0 or 2 and most preferably 2, n preferably is 1, 2, 3, 4 or 5, in the combination “-nO-” it preferably is 1, 2, 3 or 4, preferably 2 or 4, m preferably is 1, 2, 3, 4 or 5, in the combination “-Om” it preferably is 1, 2, 3 or 4, more preferably 2 or 4. The combination IVm” preferably is “2V1”.)

[0957] Table D

[0958]

[0959] CP-n-F

[0960]

[0961] CCG-n-F

[0962]

[0963] CCEP-n-OT

[0964]

[0965] CGG-n-OD

[0966]

[0967] CCPU-n-F

[0968]

[0969] DPGU-n-F

[0970]

[0971] ACQU-n-F

[0972]

[0973] PGUQU(c5)-F

[0974]

[0975] DGUQU-n-F

[0976]

[0977] CC-n-m

[0978]

[0979] CC-V-Vm

[0980]

[0981] CVC-n-Vm

[0982]

[0983] CCP-n-Om

[0984]

[0985] CCVC-n-V

[0986]

[0987] PGP-n-m

[0988]

[0989] CPGP-n-m

[0990]

[0991] CLPC-n-m

[0992] - 6 -

[0993]

[0994] PPGU-n-F

[0995]

[0996] COY-n-Om

[0997]

[0998] CCY-n-m

[0999]

[1000] CPY-n-m

[1001]

[1002] PYP-n-Vm

[1003]

[1004] CY-V-n

[1005]

[1006] CY-nVI-Om

[1007]

[1008] PY-nVI-m

[1009]

[1010] CCY-VI-Om

[1011]

[1012] CPY-VI-Om

[1013]

[1014] B-Vn-IV

[1015]

[1016]

[1017] B(P)-n-Om

[1018]

[1019] Table E

[1020] Table E shows illustrative reactive mesogenic compounds which can be used in the LC media in accordance with the present invention.

[1021]

[1022] RM-5 RM-6

[1023]

[1024] RM-17 RM-18

[1025]

[1026]

[1027] RM-42

[1028]

[1029] RM-51

[1030]

[1031] RM-62 RM-63

[1032]

[1033] RM-74 RM-75

[1034]

[1035] RM-86 RM-87

[1036]

[1037]

[1038] RM-103

[1039]

[1040] RM-109 RM-110

[1041]

[1042]

[1043] RM-125 RM-126

[1044]

[1045]

[1046]

[1047] RM-151 RM-152

[1048]

[1049]

[1050] RM-171 RM-172

[1051]

[1052] RM-181 RM-182

[1053]

[1054] In a preferred embodiment, the mixtures according to the invention comprise one or more polymerizable compounds, preferably selected from the polymerizable compounds of the formulae RM-1 to RM-182. Of these, compounds RM-1, RM-4, RM-8, RM-17, RM-19, RM- 35, RM-37, RM-39, RM-40, RM-41, RM-48, RM-52, RM-54, RM-57, RM-58, RM-64, RM- 74, RM-76, RM-88, RM-91, RM-102, RM-103, RM-109, RM-116, RM-117, RM-120, RM- 121, RM-122, RM-139, RM-140, RM-142, RM-143, RM-145, RM-146, RM-147, RM-149, RM-156 to RM-163, RM-169, RM-170 and RM-171 to RM-183 are particularly preferred.

[1055] Examples

[1056] The present invention is illustrated in detail by the following non-restrictive working examples.

[1057] The following abbreviations and symbols are used:

[1058] V0threshold voltage, capacitive [V] at 20°C,

[1059] neextraordinary refractive index at 20°C and 589 nm,

[1060] n0ordinary refractive index at 20°C and 589 nm,

[1061] Δn optical anisotropy at 20°C and 589 nm,

[1062] ε⊥dielectric permittivity perpendicular to the director at 20°C and 1 kHz,

[1063] ε||dielectric permittivity parallel to the director at 20°C and 1 kHz,

[1064] Δε dielectric anisotropy at 20°C and 1 kHz,

[1065] cl.p., T(N, I) clearing point [°C],

[1066] γ1rotational viscosity at 20°C [mPa·s],

[1067] K1elastic constant, "splay" deformation at 20°C [pN],

[1068] K2 elastic constant, "twist" deformation at 20°C [pN],

[1069] K3 elastic constant, "bend" deformation at 20°C [pN].

[1070] Unless explicitly noted otherwise, all concentrations in the present application are quoted in per cent by weight and relate to the corresponding mixture as a whole, comprising all solid or liquid-crystalline components, without solvents. 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.

[1071] All physical properties are and have been determined in accordance with "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status Nov. 1997, Merck KGaA, Germany, and apply for a temperature of 20°C, and An is determined at 589 nm and Δε at 1 kHz, unless explicitly indicated otherwise in each case.

[1072] The term "threshold voltage" for the present invention relates to the capacitive threshold (Vo), 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 (V10).

[1073] 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.

[1074] 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.

[1075] The display used for measurement of the capacitive threshold voltage consists of two plane-parallel glass outer plates with a distance of 25 pm, each of which has on the inside an electrode layer and an unrubbed polyimide alignment layer on top, which effect homeotropic alignment of the liquid-crystal molecules.

[1076] 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 pm, 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 liquidcrystal molecules.

[1077] The polymerisable compounds are polymerised in the display or test cell by irradiation with UV light of defined intensity for a prespecified time, with a voltage simultaneously being applied to the display (usually 10 V to 30 V alternating current, 1 kHz). In the examples, unless indicated otherwise, a fluorescent lamp and an intensity of 0 to 20 mW / cm2is used for polymerisation. The intensity is measured using a standard meter (Ushio Accumulate UV meter with central wavelength of 313nm).

[1078] The transmission measurements are performed in test cells with fishbone electrode layout (from Merck Ltd., Japan; 1 pixel fishbone electrode (ITO, 10x10 mm, 47.7° angle of fishbone with 3pm line / 3pm space), 3.2 pm cell gap, AF-glass, tilt angle 1°).

[1079] The storage stability in the bulk (LTSbuik) of the media according to the invention at a given temperature T is determined by visual inspection. 2 g of the media of interest are filled into a closed glass vessel (bottle) of appropriate size placed in a refrigerator at a predetermined temperature. The bottles are checked at defined time intervals for the occurrence of smectic phases or crystallisation. For every material and at each temperature two bottles are stored. If crystallisation or the appearance of a smectic phase is observed in at least one of the two correspondent bottles the test is terminated and the time of the last inspection before the one at which the occurrence of a higher ordered phase is observed is recorded as the respective storage stability.

[1080] Mixture Examples

[1081] The following stabilisers are used:

[1082]

[1083]

[1084]

[1085] The following dyes are used:

[1086]

[1087]

[1088] The nematic LC host mixtures H1 to H6, dye doped host mixtures D1 and D2, comparative Examples, and mixture examples M1 to M3 have the compositions and the properties given in the following tables. Host Mixture H1

[1089] CC-3-V 47.5 % T(N,I)[°C]: 74.8 CC-3-V1 7.5 % Δn (589 nm, 20°C): 0.1220 CLP-3-T 7.0 % ne(20°C, 589.3 nm]: 1.6125 CPGU-3-OT 2.0 % n0(20°C, 589.3 nm]: 1.4905 PGP-2-2V 16.0 % Δε (1 kHz, 20°C): 4.9 PGU-2-F 11.0 % ε||(1 kHz, 20°C): 7.9 PGUQU-3-F 6.0 % ε⊥(1 kHz, 20°C): 2.9 PP-1-2V1 2.0 % K1[pN], (20°C): 14.3 PPGU-3-F 1.0 % K3 [pN], (20°C): 12.9 X 100.0 % γ1[mPa·s], (20°C): 53

[1090] V0[V], (20°C): 1.80

[1091] Host Mixture H2

[1092] B(S)-2O-O4 4.0 % T(N,I)[°C]: 93.1 B(S)-2O-O5 4.0 % Δn (589 nm, 20°C): 0.0902 CC-3-V 41.0 % ne(20°C, 589.3 nm]: 1.5682 CC-3-V1 3.5 % n0(20°C, 589.3 nm]: 1.4780 CCP-3-1 4.5 % Δε (1 kHz, 20°C): -3.5 CCY-3-01 5.0 % ε||(1 kHz, 20°C): 3.5 CCY-3-02 7.0 % ε⊥(1 kHz, 20°C): 7.1 CLY-3-02 6.5 % Ki [pN], (20°C): 16.3 CLY-3-03 6.0 % K3 [pN], (20°C): 17.8 CPY-3-02 10.0 % γ1[mPa·s], (20°C): 91 CY-3-02 7.0 % V0[V], (20°C): 2.38 PGIY-2-04 1.5 %

[1093] X 100.0 %

[1094] Host Mixture H3

[1095] CC-3-V 47.5 % T(N,I)[°C]: 74.6 CC-3-V1 7.5 % Δn (589 nm, 20°C): 0.1223 CLP-3-T 7.0 % Δε (1 kHz, 20°C): 4.9 CPGU-3-OT 2.0 %

[1096] PGP-2-2V 16.5 %

[1097] PGU-2-F 11.0 % PGUQU-3-F 6.0 %

[1098] PP-1-2V1 2.0 %

[1099] PGPNp-5-H 0.5 %

[1100] E 100.0 %

[1101] Host Mixture H4

[1102] CC-3-V 47.5 % T(N,I) [°C]: 74.2 CC-3-V1 7.5 % An (589 nm, 20°C): 0.1213 CLP-3-T 7.0 % Δε (1 kHz, 20°C): 4.9 CPGU-3-OT 2.0 % yi [mPa s], (20°C): 53 PGP-2-2V 16.0 %

[1103] PGU-2-F 11.0 %

[1104] PGUQU(1)-3-F 4.0 %

[1105] PGUQU-(c3)-F 2.0 %

[1106] PP-1-2V1 2.0 %

[1107] PPGU-3-F 1.0 %

[1108] S 100.0 %

[1109] Host Mixture H5

[1110] B(S)-2O-O4 4.0 % T(N, I) [°C]: 94.7 B(S)-(c5) 10-02 4.0 % An (589 nm, 20°C): 0.0900 CC-3-V 41.0 % As (1 kHz, 20°C): -3.4 CC-3-V1 3.5 % yi [mPa s], (20°C): 90 CCP-V-1 2.5 %

[1111] CCP-3-2V1 2.0 %

[1112] CCY-3-01 5.0 %

[1113] CCY-3-02 7.0 %

[1114] CLY-3-02 6.5 %

[1115] CLY-3-03 6.0 %

[1116] CPY-3-02 10.0 %

[1117] CY-3-02 7.0 %

[1118] PGIY-2-04 1.5 %

[1119] 100.0 % Host Mixture H6

[1120] B(S)-2O-O4 3.0 % T(N, I) [°C]: 93 B(S)-2O-O5 2.0 % An (589 nm, 20°C) 0.0865 CC-3-V 41.0 % Δε (1 kHz, 20°C): -3.5 CC-3-V1 3.5 % Yi [mPas], (20°C): 93 CCP-3-1 4.5 %

[1121] CCY-3-01 5.0 %

[1122] CCY-3-02 7.0 %

[1123] CLY-3-02 5.5 %

[1124] CLY-3-03 5.0 %

[1125] CCOY-3-O2 4.0 %

[1126] CPY-3-02 10.0 %

[1127] CY-3-02 7.0 %

[1128] PGIY-2-04 1.5 %

[1129] 100.0 %

[1130] Host Mixture H7

[1131] CC-3-V 34.0 % T(N, I) [°C]: 83 CC-3-V1 6.0 % An (589 nm, 20°C) 0.1048 PP-1-2V1 3.0 % As (1 kHz, 20°C): -4.0 CY-3-02 15.0 %

[1132] CLY-3-02 8.0 %

[1133] CLY-4-02 11.0 %

[1134] CPY-1V-O2 8.0 %

[1135] PPY-3-02 2.5 %

[1136] B(S)-(c5-3en) 10-02 6.0 %

[1137] B(S)-(c5-3en) 10-04 6.0 %

[1138] PGPNp-3-H 0.5%

[1139] 100.0 %

[1140] Host Mixture H8

[1141] CC-3-V 50.0 % T(N,I) [°C]: 79 DUQU-3-F 3.0 % An (589 nm, 20°C) 0.1144 CCP-V-1 7.0 % As (1 kHz, 20°C): 5.5 CPP-3-2 6.0 % PGP-1-2V 7.0 %

[1142] PGP-2-2V 10.0 %

[1143] PUQU-3-F 3.0 %

[1144] CDUQU-3-F 3.0 %

[1145] PGUQU-3-F 4.0 %

[1146] PGUQU-4-F 2.0 %

[1147] DGUQU-3-F 2.5 %

[1148] DGUQU-4-F 2.0 %

[1149] PPGU-(c5)-F 0.5%

[1150] 100.0 %

[1151] Host Mixture H9

[1152] CC-3-V 9.0 % T(N, I) [°C]: 145 CC-3-V1 11.0 % An (589 nm, 20°C) 0.0946 CC-3-2V1 10.0 % Δε (1 kHz, 20°C): -3.5 CC-5-V1 10.0 %

[1153] CCP-3-1 7.0 %

[1154] CCY-3-02 9.0 %

[1155] CCY-5-02 7.0 %

[1156] CLY-3-02 8.0 %

[1157] CLY-1V-O2 7.0 %

[1158] CCEY-3-02 14.0 %

[1159] CCOY-3-O2 7.0 %

[1160] CCZPC-3-3 5.0 %

[1161] 100.0 %

[1162] Host Mixture H10

[1163] CC-2-3 23.0 % T(N, I) [°C]: 73 CC-3-4 7.0 % An (589 nm, 20°C) 0.0972 PP-1-3 12.0 % As (1 kHz, 20°C): -3.8 CCP-3-1 8.0 %

[1164] COY-3-O1 3.0 %

[1165] COY-3-O2 11.0 %

[1166] CPY-2-02 8.0 %

[1167] CPY-3-02 9.0 % CPY-4-02 4.0 %

[1168] CCOY-2-O2 3.0 %

[1169] COY-3-O2 12.0 %

[1170] 100.0 %

[1171] The medium H10 contains 0.3% of RM-19, 200 ppm of the compound ST-3a-1 and 200 ppm of ST-1.

[1172] Host Mixture H11

[1173] CC-3-V 31.0 % T(N, I) [°C]: 82 CC-3-V1 12.0 % An (589 nm, 20°C): 0.1054 CC-3-5 2.0 % Δε (1 kHz, 20°C): -4.0 PY-3-02 8.0 %

[1174] COY-3-O2 6.0 %

[1175] CCY-3-02 2.0 %

[1176] CLY-3-02 7.0 %

[1177] CLY-4-02 4.0 %

[1178] CPY-2-02 10.0 %

[1179] CPY-3-02 11.0 %

[1180] B(S)-(c5) 1O-O4 7.0 %

[1181] 100.0 %

[1182] Host Mixture H12

[1183] CY-3-02 8.0 % T(N,I) [°C]: 74.9 PY-3-02 8.0 % An (589 nm, 20°C): 0.1204 CLY-3-02 5.0 % Δε (1 kHz, 20°C): -4.0 CLY-3-03 5.0 % γ1 [mPa·s], (20°C): 98 CPY-2-02 9.0 %

[1184] CPY-3-02 9.0 %

[1185] B(S)-2O-O4 4.0 %

[1186] B(S)-2O-O5 4.0 %

[1187] PGIY-2-04 3.0 %

[1188] PYP-2-3 6.0 %

[1189] CC-3-V 35.0 %

[1190] CC-3-V1 3.0 % PP-3-2 1.0 %

[1191] 100.0 %

[1192] Host Mixture H13

[1193] B(S)-2O-O4 4.0 cl.p. [°C]: 110.1 B(S)-2O-O5 3.0 ne[589 nm, 20°CJ: 1.5865 B(S)-2O-O6 4.0 n0[589 nm, 20°CJ: 1.4840 CC-3-V 10.5 An [589 nm, 20°C] 0.1025 CC-3-V1 11.0 ε‖ [1 kHz, 20°C]: 3.2 CC-4-V1 15.0 ε⊥ [1 kHz, 20°C]: 7.0 CCH-35 12.0 AE [1 kHz, 20°CJ: -3.8 CCP-3-1 5.0 Ki [pN, 20°CJ: 24.7 CCP-3-3 1.0 K3[pN, 20°CJ: 22.6 CCY-3-02 9.0 K3 / K1 [pN, 20°CJ: 0.91 CLOY-3-O2 3.5 Vo[V, 20°CJ: 2.57 CLY-3-02 7.0

[1194] CLY-5-02 5.0

[1195] COB(S)-2-O4 10.0

[1196] X 100.0

[1197] The Host Mixture H13 contains 350 ppm of the compound ST-3a-1.

[1198] Host Mixture H14

[1199] CC-3-V 18.0 cl.p. [°C]: 95.7 PCH-302 3.5 ne[589 nm, 20°CJ:

[1200] CC-3-V1 10.0 n0[589 nm, 20°CJ:

[1201] CC-3-2V1 5.0 An [589 nm, 20°CJ:

[1202] PP-1-2V1 8.0 e|| [1 kHz, 20°CJ: 11.2 CLU-3-F 8.0 E± [1 kHz, 20°CJ: 3.0 CCP-30CF3 6.0 AE [1 kHz, 20°CJ: 8.2 CLP-3-T 6.0 Ki [pN, 20°CJ: 18.8 CLP-V-1 5.0 K3[pN, 20°CJ: 20.4 CCP-V-1 5.0 K3 / K1 [pN, 20°CJ: 1.08 CCP-3-1 5.0 V0[V, 20°CJ: 1.64 DGUQU-4-F 3.0

[1203] PGUQU-3-F 4.0

[1204] PGUQU-5-F 5.0

[1205] CDUQU-3-F 8.0

[1206] PPGU-3-F 0.5

[1207] X 100.0

[1208] The Host Mixture H14 contains 500 ppm of the compound ST-3b-1.

[1209] Host Mixture H15

[1210] DGUQU-4-F 1.5 cl.p. [°C]: 75 PGUQU-3-F 2.0 ne[589 nm, 20°C]: 1.6304 DPGU-4-F 4.0 n0[589 nm, 20°C]: 1.4968 PPGU-3-F 0.5 An [589 nm, 20°C]: 0.1336 PGU-3-F 6.0 £|| [1 kHz, 20°C]: 6.1 PGP-2-2V 16.0 E± [1 kHz, 20°C]: 2.8 PGP-1-2V 5.0 Ac [1 kHz, 20°C]: 3.3 CC-3-V 45.0 Ki [pN, 20°C]: 14.5 CC-3-V1 5.0 K3[pN, 20°CJ: 13.6 CCP-V-1 3.5 K3 / KI [pN, 20°CJ: 0.94 PP-1-2V1 10.0 V0[V, 20°CJ: 2.22 PGP-2-3 1.5

[1211] X 100.0

[1212] The Host Mixture H15 contains 300 ppm of the compound ST-3a-1 and 75 ppm of the compound ST-12. Host Mixture H16

[1213] DGUQU-4-F 3.0 cl.p. [°C]: 75.3 PGUQU-3-F 3.0 ne[589 nm, 20°C]: 1.6270 DPGU-4-F 4.0 n0[589 nm, 20°C]: 1.4955 PPGU-3-F 0.5 An [589 nm, 20°C]: 0.1315 PGU-3-F 9.0 ε‖ [1 kHz, 20°C]: 7.6 PGP-2-2V 17.0 ε⊥ [1 kHz, 20°C]: 3.0 PGP-1-2V 3.0 Δε [1 kHz, 20°C]: 4.7 CC-3-V 47.0 Ki [pN, 20°CJ: 14.0 CC-3-V1 2.5 K3[pN, 20°CJ: 13.0 CCP-V-1 4.0 K3 / K1 [pN, 20°CJ: 0.93 PP-1-2V1 7.0 V0[V, 20°CJ: 1.83 X 100.0

[1214] The Host Mixture H16 contains 300 ppm of the compound ST-3a-1 and 500 ppm of the compound ST-16.

[1215] Host Mixture H17

[1216] CC-3-V 50.0 cl.p. [°C]: 79.4 CC-3-V1 4.5 ne[589 nm, 20°CJ: 1.5981 CCP-V-1 13.5 n0[589 nm, 20°CJ: 1.4887 CPGU-3-OT 6.0 An [589 nm, 20°CJ: 0.1094 PGP-2-2 6.5 E|| [1 kHz, 20°CJ: 8.1 PGU-2-F 10.0 Ei [1 kHz, 20°CJ: 2.9 PGUQU-3-F 7.0 As [1 kHz, 20°CJ: 5.2 PPGU-3-F 1.0 Ki [pN, 20°CJ: 12.6 PUQU-2-F 1.5 K3[pN, 20°CJ: 14.2 E 100.0 K3 / KI [pN, 20°CJ: 1.13

[1217] V0[V, 20°CJ: 1.64 The Host Mixture H17 contains 300 ppm of the compound ST-3a-1.

[1218] Host Mixture H18

[1219] CC-3-V 33.5 cl.p. [°C]: 94 CC-3-V1 9.0 ne[589 nm, 20°C]: 1.5865 CCP-V-1 6.0 n0[589 nm, 20°C]: 1.4853 CLP-3-T 8.0 An [589 nm, 20°C]: 0.1012 CLP-V-1 4.0 ε‖ [1 kHz, 20°C]: 8.4 CLU-3-F 11.0

[1220]

[1221] 2.7 PGUQU-3-F 5.5 Δε [1 kHz, 20°C]: 5.7 PGUQU-4-F 4.0 Ki [pN, 20°CJ: 18.0 PP-1-2V1 3.0 K3[pN, 20°C]: 19.1 PPGU-3-F 0.5 K3 / K1 [pN, 20°CJ: 1.06 CCP-3-1 7.0 V0[V, 20°CJ: 1.87 CC-3-2V1 4.5

[1222] DPGU-4-F 4.0

[1223] X 100.0

[1224] The Host Mixture H18 contains 500 ppm of the compound ST-3b-1.

[1225] Dye doped host mixture D1

[1226] H1 99.900 %

[1227] Dye-4-1 0.009 %

[1228] Dye-5-1 0.020 %

[1229] Dye-6-1 0.017 %

[1230] Dye-7-1 0.026 %

[1231] Dye-8-1 _ 0.028 %

[1232] S 100.0 %

[1233] Dye doped host mixture D2

[1234] H2 99.900 %

[1235] Dye-4-1 0.009 % Dye-5-1 0.020 % Dye-6-1 0.017 % Dye-7-1 0.026 % Dye-8-1 0.028 % S 100.0 %

[1236] Comparative Example C1.1

[1237] D1 99.960 % ST-3b-1 0.040 %

[1238] X 100.0 %

[1239] Comparative Example C1.2

[1240] D1 99.970 % ST-3a-1 0.030 %

[1241] X 100.0 %

[1242] Comparative Example C1.3

[1243] D1 99.995 % ST-9-1 0.005 %

[1244] S 100.0 %

[1245] Comparative Example C1.4

[1246] D1 99.560 % ST-16 0.440 %

[1247] X 100.0 %

[1248] Comparative Example C1.5

[1249] D1 99.985 % ST-12 0.015 %

[1250]

[1251] Comparative Example C1.7 D1 99.980 % ST-19-1 0.005 % ST- 12 0.015 % S 100.0 %

[1252] Comparative Example C2.1 D2 99.960 % ST-3b-1 0.040 % X 100.0 %

[1253] Comparative Example C2.2 D2 99.970 % ST-3a-1 0.030 % X 100.0 %

[1254] Comparative Example C2.3 D2 99.995 % ST-9-1 0.005 % S 100.0 %

[1255] Comparative Example C2.4 D2 99.560 % ST-16 0.440 % Σ 100.0 % Comparative Example C2.5 D2 99.985 % ST-12 0.015 % Σ 100.0 % Comparative Example C2.6 D2 99.995 % ST-19-1 0.005 % Σ 100.0 % Comparative Example C2.7

[1256] D2 99.980 %

[1257] ST-19-1 0.005 %

[1258] ST-12 0.015 %

[1259] Σ 100.0 %

[1260] Mixture Example M1

[1261] D1 99.900 %

[1262] I-1-1-1 0.100 %

[1263] Σ 100.0 %

[1264] Mixture Example M2

[1265] D2 99.900 %

[1266] I-1-1-1 0.100 %

[1267] Σ 100.0 %

[1268] Stress tests

[1269] UV and backlight stress tests were performed with the above mixtures as follows. Test cells (AF glass, 1cm x 1cm ITO electrodes, cell gap 3.5 pm) with a polyimide alignment layer (SE6514, Nissan Chemical Industries, Japan), layer thickness 65 nm, rubbed) were filled with the corresponding mixtures, and their voltage holding ratio is measured before and after irradiation using the measurement system Model 6254 from Toyo Corporation, Japan.

[1270] UV: The test cells were irradiated with UV light by exposure to a Fe-I lamp with 340nm filter, with a dose of 8J.

[1271] Backlight (BL): The test cells were irradiated by exposure to commercial LCD TV white backlight (CCFL) without filter. The temperature of the test cells during the irradiation was about 50°C due to the heat evolution of the backlight.

[1272] Voltage Holding Ratio (VHR): The VHR was determined at 60°C and after 30 minutes storage, at a voltage of 1V at a frequency of 0.6Hz. The results are summarised in the following table 1 and table 2.

[1273]

[1274] Addition of dyes to the host mixture H1 or H2 causes a drop of the VHR (mixtures D1 and D2), which is not or only moderately improved by stabilisers known from prior art in the comparative mixtures C1.1 to C2.7. Surprisingly, the use of a stabiliser of the formula I in the medium according to the invention achieves a VHR that is significantly improved and even higher than the VHR of the host H1 or H2 alone, despite the presence of the dyes.

[1275] Mixture Example M3

[1276] D2 99.900 %

[1277] I-1-1-1 0.080 %

[1278] ST-3b-1 0.020 %

[1279] X 100.0 %

[1280] Dye-doped host mixtures D3 to D18 each contain 99.9% of their corresponding host mixtures H3 to H18. Additionally, they include the following percentages of dyes: 0.009% of Dye-4-1, 0.020% of Dye-5-1, 0.017% of Dye-6-1, 0.026% of Dye-7-1, and 0.028% of Dye-8-1.

[1281] Mixture Examples M4 to M19 each contain 99.900 % of their corresponding host mixtures H3 to H18, and additionally 0.100 % of the compound of formula I-1-1-1.

Claims

Patent Claims1. A liquid crystal medium comprisinga) a dichroic dye, andb) one or more compounds of the formula Iin whichW denotes CH4-sor an aromatic hydrocarbon group having 6 to 40 C atoms or a heteroaromatic hydrocarbon group having 4 to 40 C atoms;A on each occurrence, identically or differently, denotes a single bond or a straight chain alkylene radical having 1 to 20 C atoms or a straight chain alkenylene radical having 2 to 20 C atoms or a branched alkylene or alkenylene radical each having 3 to 12 C atoms, where one or more CH2groups in these radicals may each be replaced, independently of one another, by -C≡C-,-CH=CH-, -C(O)-, -O-, -CO-O- or-O-CO- in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen and in which one or two H atoms may be replaced by a group -ZS-HA;Rsdenotes H, alkyl having 1 to 12 C atoms or alkenyl having 2 to 12 C atoms;ZSdenotes -O-, -C(O)O-, -(CH2)z- or -(CH2)zO-, or a single bond;HA denotesRS1, RS2, RS3and RS4, identically or differently, denote alkyl having 1 to 6 C atoms;G on each occurrence, identically or differently, denotes H or Rsor a group ZS-HA;z is an integer from 1 to 6;t is 0 or 1, ands is 2, 3 or 4;with the proviso that if s is 2, t is 1 and at least one of the groups G denotes ZS-HA.

2. The liquid crystal medium according to claim 1, wherein the one or more dichroic dyes are selected from azo compounds, anthraquinones, thiophenolanthraquinones, methine compounds, azomethine compounds, merocyanine compounds, naphthoquinones, tetrazines, pyrromethene dyes, malononitrile dyes, nickel dithiolenes, phthalocyanines, naphthalocyanines, porphyrins, rylenes, thiadiazole dyes, thienothiadiazole dyes, benzothiadiazoles, thiadiazoloquinoxalines and diketopyrrolopyrroles.

3. The liquid crystal medium according to claim 1, wherein the one or more compounds of the formula I are selected from the compounds of the formulae 1-1, I-2 and I-3:in whichA and Rshave the meanings defined in claim 1, andW1denotes linear or branched, optionally unsaturated alkylene having 1 to 12 C atoms, in which one or more non-adjacent -CH2- groups may be replaced with -O-.

4. The liquid crystal medium according to one or more of claims 1 to 3, wherein the liquid crystal medium has positive dielectric anisotropy and comprises one or more compounds selected from the group of compounds of the formulae II and IIIin whichR2and R3, independently of one another, denote H, straight chain alkyl or alkoxy each having 1 to 15 C atoms, straight chain alkenyl or alkenyloxy each having 2 to 15 C atoms or branched alkyl, alkoxy, alkenyl,alkenyloxy each having 3 to 15 C atoms, where one or more CH2groups in these radicals may each be replaced, independently of one another,-O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen;L31and L32independently of each other, denote H or F,Y2and Y3identically or differently, denote H or CH3,X2and X3independently of each other, denote halogen, halogenated alkyl or halogenated alkoxy with 1 to 3 C-atoms or halogenated alkenyl or halogenated alkenyloxy with 2 or 3 C-atoms,Z3denotes -CH2CH2-, -CF2CF2-, -COO-, trans- -CH=CH-, trans-CF=CF-, -CH2O- or a single bond, andI, m, n and o are, independently of each other, 0 or 1.

5. The liquid crystal medium according to claim 4, wherein the medium comprises one or more compounds of formula II selected from the compounds of the formulaein whichL23and L24denote H or F,and L21, L22, R2, X2and the ring elements A22and A23have the meanings given in claim 4.

6. The liquid crystal medium according to claim 4, wherein the medium comprises one or more compounds of formula III selected from the compounds of the formulaein which R3, X3, L31, L32, the ring elements A31, A32and A33, and n and o have the meanings defined in claim 4.

7. The liquid crystal medium according to one or more of claims 1 to 3, wherein the liquid crystal medium has negative dielectric anisotropy and comprises one or more compounds selected from the group of compounds of the formulae NIIA, NIIB, NIIC,in whichR2A, R2B, R2C, R2D, R31and R32identically or differently, denote H, straight chain alkyl or alkoxy having 1 to 15 C atoms, straight chain alkenyl or alkenyloxy having 2 to 15 C atoms or branched alkyl, alkoxy, alkenyl, alkenyloxy each having 3 to 15 C atoms, where one or more CH2 groups in these radicals may each bereplaced, independently of one another, by-CH=CH-, -C≡C-, -CF2O-, -OCF2-, -0-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen,L1, L2, L31and L32, each, independently of one another, denote F, Cl, CF3or CHF2, Y denotes H, F, Cl, CF3, CHF2or CH3,Z2, Z2Band Z2Deach, independently of one another, denote a singlebond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF- or -CH=CHCH2O-,A31on each occurrence, independently of one another, denotesa) 1,4-cyclohexenylene or 1,4-cyclohexylene radical, in which one or two non- adjacent CH2 groups may be replaced by -O- or -S-,b) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N, orc) a radical from the group spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]- octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1, 2,3,4- tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, where the radicals a), b) and c) may be mono- or polysubstituted by halogen atoms,Z31on each occurrence independently of one another denotes -CO-O-,-O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-CH2O-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond, andW denotes O or S,n is 0, 1, or 2,p is 0, 1 or 2,q is 0 or 1, andv is an integer from 1 to 6.

8. The liquid crystal medium according to claim 4, wherein the medium additionally comprises one or more compounds selected from the compounds of the formulae NIIA, NIIB, NIIC, NIID, and NIII defined in claim 7.

9. The liquid crystal medium according to one or more of claims 1 to 8, wherein the medium comprises one or more compounds of the formula IVin whichR41denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, andR42denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms, or an unsubstituted alkenyl radical having 2 to 7 C atoms.

10. The liquid crystal medium according to one or more of claims 1 to 9, wherein the medium comprises one or more compounds of the VVin whichR51and R52, identically or differently, denote alkyl having 1 to 7 C atoms, alkoxy having 1 to 7 C atoms, or alkoxyalkyl, alkenyl or alkenyloxy each having 2 to 7 CZ51, Z52each, independently of one another, denote -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, andn is 1 or 2.

11. The liquid crystal medium according to one or more of claims 1 to 10, wherein the medium comprises one or more compounds of the formula CLin whichRLdenotes H, a straight chain or branched alkyl or alkoxy radical having 1 to 15 C atoms, or a straight chain or branched alkenyl radical having 2 to 15 C atoms, where one or more CH2groups in these radicals may each be replaced,independently of one another, by,or -O-CO- in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen,XLdenotes F, Cl, CN, CHF2, CF3, OCF3, or, identically or differently, has one of the meanings of RL,YLdenotes H, F, Cl or CH3.

12. The liquid crystal medium according to one or more of claims 1 to 11, wherein the medium comprises one or more compounds of the formula VIin whichR61and R62denote H, F, straight chain alkyl or alkoxy having 1 to 15 C atoms, straight chain alkenyl or alkenyloxy having 2 to 15 C atoms or branched alkyl, alkoxy, alkenyl, alkenyloxy each having 3 to 15 C atoms, where one or more CH2groups in these radicals may each be replaced, independently of one another, bysuch a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen,X61, X62, X63, X64, X65, and X66, identically or differently, denote H or F,Z61and Z62, identically or differently, denote CH2CH2or a single bondn6 is 0 or 1,wherein the compounds of the formula NIIB are excluded.

13. A liquid crystal display comprising the liquid crystal medium according to any one of claims 1 to 12.

14. The liquid crystal display of claim 13, wherein the display is a VA, IPS, FFS, PS- VA, PS-IPS or PS-FFS type display.

15. Use of the liquid crystal medium according to any one of claims 1 to 12 in a VA, IPS, FFS, PS-VA, PS-IPS or PS-FFS display.

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