Liquid crystal medium

Abstract

The present invention relates to a liquid crystal (LC) medium based on a mixture of polar compounds as a sub-class of liquid crystal materials, to the use thereof for optical, electro-optical and electrical purposes, in particular in LC displays, in particular in vertically aligned LC displays, to vertically aligned LC displays, in particular energy-saving LC displays, comprising such an LC medium, and to the use thereof for optical, electro-optical and electrical purposes, in particular in vertically aligned LC displays, in particular in vertically aligned LC displays, in particular in vertically aligned LC displays, in particular in vertically aligned LC displays, in particular in vertically aligned LC displays, in particular in vertically aligned LC displays, in particular in vertically aligned LC displays. The invention also relates to a method for manufacturing the LC display.

Description

Field of the Invention

[0001] The present invention relates to liquid crystal (LC) media (as a subcategory of liquid crystal materials) based on mixtures of polar compounds, to their use for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays in the vertical alignment mode, to vertical alignment mode LC displays comprising said LC media, especially energy-saving LC displays, and to a method of manufacturing said LC displays. Background Art

[0002] The spread of 8K and gaming monitors has led to an increased demand for LC display (LCD) panels with a higher refresh rate, and thus an increased demand for LC media with a faster response time. Many of these LCD panels use a display mode in which the LC molecules are aligned substantially perpendicular or slightly tilted with respect to the electrode surface in the off state.

[0003] Thus, so-called VA ("vertical alignment") displays are known, which have a wide viewing angle and a fast response time. The LC cell of a VA display contains an LC medium layer between two transparent electrodes, where the LC medium typically has a negative dielectric anisotropy (Δε) value. In the off state, the molecules of the LC layer are aligned perpendicular to the electrode surface (vertical alignment) or have an inclined vertical alignment. When a voltage is applied to the two electrodes, reorientation of the LC molecules parallel to the electrode surface occurs.

[0004] Furthermore, so-called FFS ("fringe field switching") displays have been reported (see in particular S.H. Jung et al., Jpn. J. Appl. Phys., Vol. 43, No. 3, 2004, 1028), which contain two electrodes on the same substrate, one of the two electrodes being structured in a comb-like manner and the other being unstructured. This results in a strong so-called "fringe field", i.e. a strong electric field near the electrode edges, and an electric field having both a strong vertical component and a strong horizontal component throughout the cell. FFS displays have a low viewing angle dependence of the contrast. FFS displays usually contain an LC medium with a positive dielectric anisotropy and an alignment layer, usually made of polyimide, which provides planar alignment for the molecules of the LC medium.

[0005] FFS displays can operate as active matrix or passive matrix displays. In the case of an active matrix display, individual pixels are usually addressed by integrated non-linear active elements (such as transistors (such as thin film transistors ("TFT"))), while in the case of a passive matrix display, individual pixels are usually addressed by multiplexing methods, as known from the prior art.

[0006] It is also known for the so-called IPS (“in-plane switching”) display, which includes an LC layer with planar alignment between two substrates, where two electrodes are arranged only on one of the two substrates and preferably have an intersecting comb structure. When a voltage is applied to the electrodes, an electric field with a significant component parallel to the LC layer is generated between them. This causes the reorientation of the LC molecules in the layer plane.

[0007] In addition, FFS displays have been disclosed (see S.H. Lee et al., Appl. Phys. Lett. 73(20), 1998, 2882-2883 and S.H. Lee et al., Liquid Crystals 39(9), 2012, 1141-1148), which have a similar electrode design and layer thickness as the FFS display, but include a layer with an LC medium having negative dielectric anisotropy instead of an LC medium having positive dielectric anisotropy. Compared with an LC medium having positive dielectric anisotropy, an LC medium having negative dielectric anisotropy shows a more favorable director orientation with less tilt and more twist orientation. As a result, these displays have a higher transmittance.

[0008] In addition, VA displays using an alignment layer prepared by photo-alignment have been disclosed, also known as UV 2 A mode (see, for example, Q. Tang et al., SID Symposium Digest of Technical Papers 2018, 414-417). These displays utilize an alignment layer prepared by obliquely irradiating a crosslinkable and photo-alignable monomer or prepolymer, such as a cinnamate chromophore, with linearly polarized UV light. Thus, a crosslinked alignment layer is formed, which induces a uniaxial alignment with a pretilt angle in the LC molecules near its surface. By changing the irradiation direction, a multi-domain structure with different pretilt directions can be obtained.

[0009] However, there are also several disadvantages in using an LC medium with negative dielectric anisotropy in VA or FFS displays. For example, compared with an LC medium having positive dielectric anisotropy, they have significantly lower reliability.

[0010] The term “reliability” used hereinafter refers to the performance quality of a display over a period of time and under different stress loads (such as light load, temperature, humidity, or voltage) that cause defects in the display (such as image retention (surface and line image retention), non-uniformity (mura), stain (yogore), etc.) and are known to those skilled in the art of LC displays. As a standard parameter for classifying reliability, the voltage holding ratio (VHR) value is usually used, which is a measure of maintaining a constant voltage in the test display. The higher the VHR value, the better the reliability of the LC medium.

[0011] The reduced reliability of LC media with negative dielectric anisotropy in VA or FFS displays can be explained by the interaction of LC molecules with the polyimide of the alignment layer. As a result, ions are extracted from the polyimide alignment layer, and LC molecules with negative dielectric anisotropy are indeed more effective in extracting such ions.

[0012] This leads to new requirements for the LC media used in VA or FFS displays. In particular, the LC media must exhibit high reliability and high VHR values after UV exposure. Further requirements are high specific resistance, a large operating temperature range, short response times even at low temperatures, low threshold voltages, multiple gray levels, high contrast, wide viewing angles, and reduced image retention.

[0013] Thus, in displays known in the prior art, the undesirable effect of so-called "image retention" or "image burn-in" is often observed, where the image generated in the LC display by the temporary addressing of individual pixels remains visible even after the electric field in these pixels has been switched off, or after other pixels have been addressed.

[0014] On the one hand, this "image retention" can occur if an LC medium with low VHR is used. The UV component of sunlight or backlight can cause undesirable decomposition reactions of the LC molecules therein and thus trigger the generation of ionic or radical impurities. These can accumulate particularly at the electrodes or the alignment layer, where they can reduce the effectively applied voltage.

[0015] Another problem observed in the prior art is that LC media for displays (including but not limited to VA and FFS displays) often exhibit high viscosities and thus high switching times. To reduce the viscosity and switching time of the LC media, it has been proposed in the prior art to add LC compounds with alkenyl groups. However, it has been observed that LC media containing alkenyl compounds often exhibit a reduction in reliability and stability, as well as a reduction in VHR, especially after exposure to UV radiation and visible light from the backlight of displays that typically do not emit UV light.

[0016] Especially for certain FFS display modes, such as UB-FFS ("Ultra Bright FFS") and UBplus modes, in addition to fast switching times, there is a strong market expectation to obtain high contrast to achieve an excellent black state. A possible way to generate high contrast is to provide the LC material with elastic constants K 11 (splay), K 22 (twist), and K 33(Bent) high average value. However, it is difficult to find an LC single compound with the potential to increase the average value of the elastic constant without having a negative impact on other physical parameters. Another approach is to increase the average value of the elastic constant by increasing the clearing point of the LC mixture. However, this also results in an increase in the rotational viscosity of the LC mixture, leading to slower switching times, which is undesirable. Summary of the Invention

[0017] Accordingly, an object of the present invention is to provide a method for an improved LC medium in VA-, IPS-, or FFS displays, which does not exhibit the above-mentioned drawbacks or exhibits them only to a small extent and has improved performance. Another object of the present invention is to provide VA-, IPS-, or FFS displays having good transmittance, high reliability, especially VHR values after backlight exposure, high specific resistance, a large operating temperature range, short response times even at low temperatures, low threshold voltages, multiple gray levels, high contrast, excellent black states, wide viewing angles, and reduced image sticking.

[0018] It has been found that one or more of these objects can be achieved by providing an LC medium as disclosed and claimed below.

[0019] Accordingly, the present invention relates to an LC medium having negative dielectric anisotropy and comprising one or more compounds of formula IA

[0020]

[0021] wherein each group is the same or different each time it appears and each independently has the following meanings:

[0022] R 1A is a straight-chain, branched-chain or cyclic alkyl group having 1 to 15 C atoms, where one or more non-adjacent CH 2 - groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CR 0 =CR 00 -, -C≡C-,

[0023]

[0024] substituted, and where one or more H atoms are each optionally replaced by F or Cl, preferably an alkyl or alkoxy group having 1 to 6 C atoms,

[0025] R 2A is an alkyl or alkoxy group having 1 to 12, preferably 1 to 6 C atoms, where one or more non-adjacent CH 2The group is replaced by cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl (preferably cyclopentyl or cyclopentenyl),

[0026] L 1A , L 2A is F, Cl, CF 3 or CHF 2 ,

[0027] Y is H, F, Cl, CF 3 , CHF 2 or CH 3 , preferably H or CH 3 , particularly preferably H,

[0028] n is 0 or 1, preferably 1.

[0029] The present invention also relates to the use of the LC medium as described above in a LC display, preferably in a LC display of VA, IPS, FFS, UB-FFS or UV 2 A mode.

[0030] The present invention also relates to a method for preparing the LC medium as described above, which comprises the step of mixing one or more compounds of formula IA with one or more compounds of formula II or other compounds as described below and optionally mixing with other LC compounds and / or additives.

[0031] The present invention also relates to a LC display, which comprises the LC medium according to the present invention as described above, preferably a LC display of VA, IPS, FFS, UB-FFS or UV 2 A mode.

[0032] The present invention also relates to a method for manufacturing the LC display as described above, which comprises the step of filling or otherwise providing the LC medium as described above between the substrates of the display.

[0033] When used in a LC display, the LC medium according to the present invention exhibits one or more of the following advantageous properties:

[0034] - High transmittance,

[0035] - High contrast

[0036] - Low birefringence,

[0037] - Reduced image retention,

[0038] - Reduced ODF non-uniformity,

[0039] - Reduced rotational viscosity,

[0040] - High reliability and high VHR value after UV exposure and / or heat treatment,

[0041] - Fast response time,

[0042] - Favorable low ratio γ of rotational viscosity to splay elastic constant 1 / K 1 , which helps to improve the switching behavior, especially at low driving voltages, and is useful for achieving energy-saving displays,

[0043] - Low threshold voltage, which is useful for achieving energy-saving displays.

[0044] Surprisingly, it has been found that by adding one or more compounds of formula IA to the LC medium according to the present invention, the birefringence of the LC medium can be reduced without affecting or with little effect on its other physical parameters. Since the contrast is inversely proportional to the square of the birefringence of the LC medium, the contrast can be increased and a high contrast and excellent black state can be achieved, especially in UB-FFS mode displays, without negatively affecting other parameters of the LC medium.

[0045] Furthermore, surprisingly, the LC medium according to the present invention exhibits a favorable combination of low rotational viscosity and high average elastic constant K avg . This also enables the achievement of a low scattering parameter, thereby achieving a high contrast.

[0046] Furthermore, in terms of reliability, the LC medium according to the present invention exhibits a high VHR value and little or no unwanted inhomogeneity effects, such as edge inhomogeneity.

[0047] The alkenyl groups in the compounds of the LC medium disclosed below are not considered to be included within the meaning of the term "polymerizable group" as used herein. The conditions for the selection of the polymerizable compounds for polymerizing the LC medium are preferably such that the alkenyl substituents do not participate in the polymerization reaction. Preferably, the LC media disclosed and claimed in the present application do not contain additives that initiate or enhance the participation of alkenyl groups in the polymerization reaction.

[0048] Unless otherwise specified, the compounds disclosed in the context are preferably selected from achiral compounds, except for chiral dopants.

[0049] As used herein, the expression "UV light having... wavelength" followed by the given wavelength range (in nm) or the given wavelength lower or upper limit (in nm) means that the UV emission spectrum of the corresponding radiation source has such an emission peak, which is preferably the highest peak in the corresponding spectrum, within the given wavelength range or above the given wavelength lower limit or below the given wavelength upper limit, and / or means that the UV absorption spectrum of the corresponding compound has a long or short wavelength tail that extends into the given wavelength range or above the given wavelength lower limit or below the given wavelength upper limit.

[0050] As used herein, the term "substantially transmissive" means that the filter transmits a majority, preferably at least 50% of the intensity, of the incident light at one or more desired wavelengths. As used herein, the term "substantially blocking" means that the filter does not transmit a majority, preferably at least 50% of the intensity, of the incident light at undesired wavelengths. As used herein, the term "desired (undesired) wavelength" means, for example in the case of a bandpass filter, a wavelength within (outside) a given range of λ, and in the case of a cut-off filter, a wavelength above (below) a given value of λ.

[0051] As used herein, the terms "active layer" and "switchable layer" mean a layer in an electro-optical display (such as an LC display) that contains one or more molecules having structural and optical anisotropy, such as LC molecules, which change their orientation when subjected to an external stimulus such as an electric or magnetic field, resulting in a change in the transmissivity of the layer to polarized or unpolarized light.

[0052] As used herein, the terms "tilt" and "tilt angle" will be understood to mean the tilted alignment of the LC molecules of the LC medium with respect to the cell surface in an LC display (preferably a PSA display herein), and will be understood to include "pretilt" and "pretilt angle". Herein, the tilt angle represents the average angle (<90°) between the longitudinal molecular axis (LC director) of the LC molecules and the surface of the outer plate parallel to the plane forming the LC cell. Herein, a low absolute value of the tilt angle (i.e., a large deviation from the 90° angle) corresponds to a large tilt. A suitable method for measuring the tilt angle is given in the examples. Unless otherwise indicated, the tilt angle values disclosed above and below relate to this measurement method.

[0053] As used herein, the terms "reactive mesogen" and "RM" will be understood to mean a compound containing a mesogenic or liquid crystalline backbone and one or more functional groups attached thereto, which functional groups are suitable for polymerization and are also referred to as "polymerizable groups" or "P".

[0054] Unless otherwise specified, the term "polymerizable compound" as used herein will be understood to mean a polymerizable monomeric compound.

[0055] The SA-VA display according to the present invention will be of the polymer-stabilized mode since it includes an LC medium containing RM (such as those described below) or is manufactured by using an LC medium containing RM (such as those described below). Thus, as used herein, the term "SA-VA display", when referring to the display according to the present invention, will be understood to refer to a polymer-stabilized SA-VA display even if not explicitly mentioned.

[0056] As used herein, the term "low molecular weight compound" is understood to mean monomeric compounds and / or compounds not prepared by a polymerization reaction as opposed to "polymeric compounds" or "polymers".

[0057] As used herein, the term "non-polymerizable compound" is understood to mean a compound that does not contain a functional group that is suitable for polymerization under conditions typically applied to polymerize RM.

[0058] The term "mesogenic group" as used herein is known to those skilled in the art and is described in the literature, and means a group that substantially contributes to the formation of a liquid crystal (LC) phase in low molecular weight or polymeric materials due to the anisotropy of its attractive and repulsive interactions. Compounds containing a mesogenic group (mesogenic compounds) do not necessarily have to exhibit an LC phase themselves. Mesogenic compounds may also only exhibit LC phase properties after mixing with other compounds and / or after polymerization. Typical mesogenic groups are, for example, rigid rod or disc-shaped units. A review of the terms and definitions used in connection with mesogenic or LC compounds is given in the following literature: Pure Appl. Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340 - 6368.

[0059] As used herein, the term "spacer group", also hereinafter referred to as "Sp", is known to those skilled in the art and is described in the literature, see, for example, Pure Appl. Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340 - 6368. As used herein, the term "spacer group" or "spacer" means a flexible group that connects a mesogenic group and one or more polymerizable groups in a polymerizable mesogenic compound, such as an alkylene group.

[0060] Above and below, represents a trans - 1,4 - cyclohexylene ring,

[0061] and represents a 1,4 - phenylene ring.

[0062] In the group the single bond shown between two ring atoms can be attached to any free position of the benzene ring.

[0063] If in the formulas shown above and below, such as R 1A,2A 、R 1 、R 2 、R11,12,13 , R 21,22 , R 31,32 , R 41,42 , R 51 ,52 , R 61,62 , R 71,72 , R 81,82,83 , R Q , R 0 , R, R M , R S , R S1,S2,S3,S4 If one of the terminal groups mentioned above represents an alkyl group and / or an alkoxy group, it can be straight-chain or branched. It is preferably straight-chain, having 2, 3, 4, 5, 6 or 7 C atoms and thus preferably represents ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy, as well as methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy or tetradecyloxy.

[0064] If one of the terminal groups mentioned above represents an alkyl group in which one or more CH 2 groups are replaced by S, it can be straight-chain or branched. It is preferably straight-chain, having 1, 2, 3, 4, 5, 6 or 7 C atoms and thus preferably represents thiomethyl, thioethyl, thiopropyl, thiobutyl, thiopentyl, thiohexyl or thioheptyl.

[0065] Oxalkyl preferably represents straight-chain 2-oxapropyl (=methoxymethyl), 2-oxabutyl (=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl.

[0066] If one of the terminal groups mentioned above represents an alkoxy or oxalkyl group, it can also contain one or more additional oxygen atoms, provided that the oxygen atoms are not directly connected to each other.

[0067] If one of the terminal groups mentioned above represents an alkyl group in which one of the CH 2An alkyl group in which the group has been replaced by -CH=CH- can be straight-chain or branched. It is preferably straight-chain and has 2 to 10 C atoms. Thus, it particularly represents vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-enyl, oct-1-, -2-, -3-, -4-, -5-, -6- or -7-enyl, non-1-, -2-, -3-, -4-, -5-, -6-, -7- or -8-enyl, dec-1-, -2-, -3-, -4-, -5-, -6-, -7-, -8- or -9-enyl.

[0068] If one of the above-mentioned end groups represents an alkyl or alkenyl group that is at least monosubstituted by a halogen, the group is preferably straight-chain and the halogen is preferably F or Cl. In the case of polysubstitution, the halogen is preferably F. The resulting group also includes fully fluorinated groups. In the case of monosubstitution, the fluorine or chlorine substituent can be at any desired position, but is preferably at the ω-position.

[0069] In another preferred embodiment, one or more of the above-mentioned end groups, such as R 1A,2A 、R 1 、R 2 、R 11 ,12,13 、R 31,32 、R 41,42 、R 51,52 、R 61,62 、R 71,72 、R 81,82,83 、R Q 、R 0 、R、R M 、R S 、R S1,S2,S3,S4 or L, are selected from the following:

[0070]

[0071] -S 1 -F, -O-S 1 -F, -O-S 1 -O-S 2 , where S 1 is C 1-12 -alkylene or C 2-12 -alkenylene and S 2 is H, C 1-12 -alkyl or C 2-12 -alkenyl, and is very preferably selected from the following:

[0072] - OCH 2 OCH 3 、 -O(CH 2 ) 3 OCH 3 、 -O(CH 2 ) 4 OCH 3 、 -O(CH 2 ) 2 F、 -O(CH 2 ) 3 F、 -O(CH 2 ) 4 F。

[0073] The halogen is preferably F or Cl, very preferably F.

[0074] The group -CR 0 =CR 00 - is preferably -CH=CH-.

[0075] -CO-, -C(=O)- and -C(O)- represent a carbonyl group, i.e.

[0076] Preferred substituents L are, for example, F, Cl, Br, I, -CN, -NO 2 、 -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x ) 2 、 -C(=O)Y 1 、 -C(=O)R x 、 -N(R x ) 2 、 a straight-chain or branched-chain alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group each having 1 - 25 C atoms, wherein one or more H atoms may optionally be replaced by F or Cl, an optionally substituted silyl group having 1 - 20 Si atoms, or an optionally substituted aryl group having 6 - 25, preferably 6 - 15 C atoms,

[0077] wherein R x represents H, F, Cl, CN, or a straight-chain, branched-chain or cyclic alkyl group having 1 - 25 C atoms, wherein one or more non-adjacent CH 2 - groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O- and / or S- atoms are not directly connected to each other, and wherein one or more H atoms are each optionally replaced by F, Cl, P- or P-Sp-, and

[0078] Y 1 represents a halogen.

[0079] Particularly preferred substituents L are, for example, F, Cl, CN, NO 2 , CH 3 , C 2 H 5 , OCH 3 , OC 2 H 5 , COCH 3 , COC 2 H 5 , COOCH 3 , COOC 2 H 5 , CF 3 , OCF 3 , OCHF 2 , OC 2 F 5 and phenyl.

[0080] Preferably

[0081] wherein L has one of the meanings indicated above.

[0082] In the compounds of formula IA and its sub-formulas, R 1A preferably represents an alkyl group having 1, 2, 3, 4, 5 or 6 C atoms, very preferably propyl.

[0083] In the compounds of formula IA, L 1A and L 2A preferably represent F or Cl, very preferably F.

[0084] In the compounds of formula IA, Y preferably represents H or CH 3 , very preferably H.

[0085] In the compounds of formula IA, R 2A is preferably selected from the following groups:

[0086]

[0087] Very preferably selected from the following groups:

[0088]

[0089] Most preferably selected from the following groups:

[0090]

[0091] In another preferred embodiment, R in formula I A2represents an alkyl or alkoxy group having 1 to 6 carbon atoms, preferably an alkoxy group, wherein one or more non-adjacent CH 2 - groups are replaced by a cyclopentyl group, and very preferably represents

[0092]

[0093] In another preferred embodiment, R in formula I A2 represents an alkyl or alkoxy group having 1 to 6 carbon atoms, preferably an alkoxy group, wherein one or more non-adjacent CH 2 - groups are replaced by a cyclopentenyl group, and very preferably represents

[0094]

[0095] Preferred compounds of formula IA are those selected from the following sub-formulas:

[0096]

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103] Very preferably, the compounds of formula IA11 to IA20 and IA31 to IA40, especially those of formula IA13, IA18, IA33 and IA38.

[0104] Preferably, the total proportion of the compound of formula IA or its sub-formula in the LC medium is 1 to 40% by weight, very preferably 2 to 30% by weight, and most preferably 3 to 20% by weight.

[0105] In another preferred embodiment, the total proportion of the compound of formula IA or its sub-formula in the LC medium is 6 to 40% by weight, very preferably 6 to 30% by weight, and most preferably 8 to 25% by weight.

[0106] The following lists further preferred embodiments of the LC medium according to the present invention, including any combination thereof:

[0107] Preferably, the LC medium further comprises one or more compounds of formula II,

[0108]

[0109] Each of the groups, independently of one another and each time it appears, is the same or different and has the following meanings

[0110] R 21 and R 22 is H, a straight-chain, branched-chain or cyclic alkyl or alkoxy group having 1 to 20 C atoms, in which one or more non-adjacent CH 2 - groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CR 0 =CR 00 -, -C≡C-,

[0111]

[0112] and one or more H atoms are each optionally replaced by F, Cl, CN or CF 3 and is preferably an alkyl or alkoxy group having 1 to 6 C atoms,

[0113] R 0 ,R 00 is H or an alkyl group having 1 to 12 C atoms,

[0114] A 1 and A 2 are groups selected from the following formulae

[0115]

[0116] preferably selected from formulae A1, A2, A3, A4, A5, A6, A9 and A10, very preferably selected from formulae A1, A2, A3, A4, A5, A9 and A10,

[0117] Z 1 and Z 2 is -CH 2 CH 2 -, -CH=CH-, -CF 2 O-, -OCF 2 -, -CH 2 O-, -OCH 2 -, -CO-O-, -O-CO-, -C 2 F 4 -, -CF=CF-, -CH=CH-CH 2 O- or a single bond, preferably a single bond,

[0118] L 1 ,L 2 ,L 3 and L 4is F, Cl, OCF 3 , CF 3 , CH 3 , CH 2 F or CHF 2 , preferably F or Cl, very preferably F,

[0119] Y is H, F, Cl, CF 3 , CHF 2 or CH 3 , preferably H or CH 3 , very preferably H,

[0120] L C is CH 3 or OCH 3 , preferably CH 3 ,

[0121] a1 is 0, 1 or 2,

[0122] a2 is 0 or 1.

[0123] Preferably, the LC medium comprises a compound of formula II selected from one or more of the compounds of formulae IIA, IIB, IIC and IID,

[0124]

[0125] where each group is the same or different at each occurrence and each independently of one another has the following meanings:

[0126] R 21 , R 22 is H, an alkyl, alkoxy or alkenyl having at most 15 (preferably at most 6) C atoms, which is unsubstituted or mono-substituted by F, Cl, CN or CF 3 , and wherein furthermore one or more CH 2 groups may be replaced by -O-, -S-, -C≡C-, -CF 2 O-, -OCF 2 -, -OC-O-, -O-CO-

[0127]

[0128] such that the O- and / or S-atoms are not directly linked to one another,

[0129] L 1 to L 4 is F, Cl, CF 3 or CHF 2 ,

[0130] Y is H, F, Cl, CF 3, CHF 2 or CH 3 , preferably H or CH 3 , particularly preferably H,

[0131] Z 1 , Z 2 is a single bond, -CH 2 CH 2 -, -CH=CH-, -CF 2 O-, -OCF 2 -, -CH 2 O-, -OCH 2 -, -COO-, -OCO-, -C 2 F 4 -, -CF=CF-, -CH=CHCH 2 O,

[0132] p is 0, 1 or 2, or

[0133] q is 0 or 1.

[0134] Preferred compounds of formulae IIA, IIB, IIC and IID are those in which R 22 represents an alkyl or alkoxy group having at most 15 C atoms and very preferably represents (O)C v H 2v+1 where (O) is an oxygen atom or a single bond and v is 1, 2, 3, 4, 5 or 6.

[0135] Further preferred compounds of formulae IIA, IIB, IIC and IID are those in which R 21 or R 22 represents or contains a cycloalkyl or cycloalkoxy group, preferably selected from

[0136]

[0137] where S 1 is C 1-12 -alkylene or C 2-12 -alkenylene, and S 2 is H, C 1-12 -alkyl or C 2-12 -alkenyl, and very preferably selected from

[0138]

[0139]

[0140] Further preferred compounds of formulae IIA, IIB, IIC and IID are indicated below.

[0141] In a preferred embodiment, the LC medium comprises one or more compounds of formula IIA selected from the following formula:

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151]

[0152] wherein the exponent a represents 1 or 2, alkyl and alkyl * each independently of one another represents a straight-chain alkyl group having 1-6 C atoms, alkenyl represents a straight-chain alkenyl group having 2-6 C atoms, and (O) represents an oxygen atom or a single bond, and alkenyl preferably represents CH 2 =CH-, CH 2 =CHCH 2 CH 2 -, CH 3 -CH=CH-, CH 3 -CH 2 -CH=CH-, CH 3 -(CH 2 ) 2 -CH=CH-, CH 3 -(CH 2 ) 3 -CH=CH- or CH 3 -CH=CH-(CH 2 ) 2 -.

[0153] A particularly preferred LC medium according to the invention comprises one or more compounds selected from formulae IIA-2, IIA-8, IIA-10, IIA-16, II-18, IIA-40, IIA-41, IIA-42 and IA-43.

[0154] In another preferred embodiment, the LC medium comprises one or more compounds of formula IIB selected from formulae IIB-1 to IIB-26,

[0155]

[0156]

[0157]

[0158]

[0159] wherein alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl represents a straight-chain alkenyl group having 2 to 6 C atoms, and (O) represents an oxygen atom or a single bond, and alkenyl preferably represents CH 2 =CH-, CH 2 =CHCH 2 CH 2 -, CH 3 -CH=CH-, CH 3 -CH 2 -CH=CH-, CH 3 -(CH 2 ) 2 -CH=CH-, CH 3 -(CH 2 ) 3 -CH=CH- or CH 3 -CH=CH-(CH 2 ) 2 -.

[0160] A particularly preferred LC medium according to the invention comprises one or more compounds selected from formulae IIB-2, IIB-10 and IIB-16.

[0161] In another preferred embodiment, the LC medium comprises one or more compounds of formula IIC selected from formula IIC-1,

[0162]

[0163] wherein alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1 to 6 C atoms, preferably in an amount of from 0.5 wt% to 5 wt%, in particular from 1 wt% to 3 wt%.

[0164] In another preferred embodiment, the LC medium comprises one or more compounds of formula IID selected from the following formulae,

[0165]

[0166]

[0167]

[0168]

[0169]

[0170] wherein alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl represents a straight-chain alkenyl group having 2 to 6 C atoms, (O) represents an oxygen atom or a single bond, and Y represents H or CH 3 and alkenyl preferably represents CH 2 =CH-, CH 2 =CHCH 2 CH 2 -, CH 3 -CH=CH-, CH 3 -CH 2 -CH=CH-, CH 3 -(CH 2 ) 2 -CH=CH-, CH 3 -(CH 2 ) 3 -CH=CH- or CH 3 -CH=CH-(CH 2 ) 2 -.

[0171] A further preferred LC medium according to the invention comprises one or more compounds of the formula IID-1 and / or IID-4.

[0172] A further preferred LC medium according to the invention comprises one or more compounds of the formula IID, where q is 0, Y is H, and R 22 represents an alkyl or alkoxy group having 1 to 6 C atoms, where one CH 2 group is optionally replaced by cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl, preferably selected from the formulas IID-1, IID-15, IID-17, IID-18, IID-19, IID-20, IID-21, IID-22 and IID-23, very preferably selected from the formulas IID-1, IID-21, IID-22 and IID-23.

[0173] Very preferred compounds of the formula IID are compounds selected from the following sub-formulas

[0174]

[0175]

[0176]

[0177]

[0178]

[0179] wherein v is 1, 2, 3, 4, 5 or 6.

[0180] In a preferred embodiment, the LC medium comprises one or more compounds of formula IID-10a

[0181]

[0182] wherein R 21 , Y and q have the meanings given in formula IID, and R 23 is wherein r is 0, 1, 2, 3, 4, 5 or 6, and s is 1, 2 or 3

[0183] Preferred compounds of formula IID-10a are selected from the following sub-formulas:

[0184]

[0185]

[0186]

[0187]

[0188] A particularly preferred LC medium according to the invention comprises one or more compounds selected from formula IIA-2, IIA-8, IIA-10, IIA-16, II-18, IIA-40, IIA-41, IIA-42, IIA-43, IIB-2, IIB-10, IIB-16, IIC-1 and IID-4 and IID-10 or their sub-formulas.

[0189] The proportion of the compounds of formula IIA and / or IIB in the overall mixture is preferably at least 20 wt%.

[0190] Preferably, the LC medium comprises one or more compounds of formula IIA-2 selected from the following sub-formulas:

[0191]

[0192] Alternatively, preferably in addition to the compounds of formula IIA-2-1 to IIA-2-5, the LC medium further comprises one or more compounds of the following formula:

[0193]

[0194]

[0195] More preferably, the LC medium comprises one or more compounds of formula IIA-10 selected from the following sub-formulas:

[0196]

[0197]

[0198] Alternatively, preferably in addition to the compounds of formulas IIA-10-1 to IIA-10-5, the LC medium further comprises one or more compounds of the following formula:

[0199]

[0200] Preferably, the LC medium comprises one or more compounds of formula IIB-10 selected from the following sub-formulas:

[0201]

[0202] Alternatively, preferably in addition to the compounds of formulas IIB-10-1 to IIB-10-5, the LC medium further comprises one or more compounds of the following formula:

[0203]

[0204]

[0205] In another preferred embodiment, the LC medium comprises one or more compounds of formula III,

[0206]

[0207] wherein

[0208] R 31 and R 32 each independently of one another represent H, an alkyl, alkoxy or alkenyl group having at most 15 C atoms, which is unsubstituted, monosubstituted by F, Cl, CN or CF 3 or at least monosubstituted by halogen, wherein furthermore one or more CH 2 groups in these groups can be replaced by -O-, -S-, -C≡C-, -CF 2 O-, -OCF 2 -, -OC-O- or -O-CO- in such a way that the O atoms are not directly linked to one another,

[0209] Y1 , Y 2 is H, F, Cl, CF 3 , CHF 2 , CH 3 or OCH 3 , preferably H, CH 3 or OCH 3 , very preferably H,

[0210] A 3 each occurrence independently represents

[0211] a) 1,4 - cyclohexenylene or 1,4 - cyclohexylene, where one or two non - adjacent CH 2 groups may be replaced by - O - or - S -,

[0212] b) 1,4 - phenylene, where one or two CH groups may be replaced by N, or

[0213] c) a group selected from 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,

[0214] where the groups a), b) and c) may be mono - or poly - substituted by halogen atoms,

[0215] n represents 0, 1 or 2, preferably 0 or 1,

[0216] Z 1 each occurrence independently represents - CO - O -, - O - CO -, - CF 2 O -, - OCF 2 -, - CH 2 O -, - OCH 2 -, - CH 2 -, - CH 2 CH 2 -, -(CH 2 ) 4 -, - CH=CH - CH 2 O -, - C 2 F 4 -, - CH 2 CF 2 -, - CF 2 CH 2 -, - CF=CF -, - CH=CF -, - CF=CH -, - CH=CH -, - C≡C - or a single bond, and

[0217] L 11 and L 12each independently represents F, Cl, CF 3 or CHF 2 , preferably H or F, most preferably F, and

[0218] W represents O or S.

[0219] In the compounds of formula III, R 31 and R 32 are preferably selected from straight-chain alkyl or alkoxy groups having 1-12, preferably 1-7, C atoms, straight-chain alkenyl groups having 2-12, preferably 2-7, C atoms, and cyclic alkyl or alkoxy groups having 3-12, preferably 3-8, C atoms.

[0220] In a preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III selected from sub-formulas III-1 and III-2,

[0221]

[0222] wherein the groups occurring have the same meanings as given above under formula III, and preferably

[0223] R 31 and R 32 are each independently an alkyl, alkenyl or alkoxy group having at most 15 C atoms, more preferably one or both of them represent an alkoxy group, and

[0224] L 11 and L 12 each preferably represents F.

[0225] In another preferred embodiment, the LC medium comprises one or more compounds of formula III-1 selected from sub-formulas III-1-1 to III-1-10, preferably formula III-1-6,

[0226]

[0227]

[0228] where alkyl and alkyl * each independently represents a straight-chain alkyl group having 1-6 C atoms, alkenyl and alkenyl * each independently represents a straight-chain alkenyl group having 2-6 C atoms, alkoxy and alkoxy * each independently represents a straight-chain alkoxy group having 1-6 C atoms, and L 11 and L 12 each independently represents F or Cl, preferably both are F.

[0229] In another preferred embodiment, the LC medium comprises one or more compounds of formula III-2, selected from compounds of sub-formulae III-2-1 to III-2-10, preferably the compound of sub-formula III-2-1,

[0230]

[0231]

[0232] wherein alkyl and alkyl * each independently of one another represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl and alkenyl * each independently of one another represent a straight-chain alkenyl group having 2 to 6 C atoms, alkoxy and alkoxy * each independently of one another represent a straight-chain alkoxy group having 1 to 6 C atoms, and L 11 and L 12 each independently of one another represent F or Cl, preferably both are F.

[0233] Highly preferred compounds of formula III-2 are selected from the following sub-formulae,

[0234]

[0235]

[0236] wherein alkoxy represents a straight-chain alkoxy group having 1 to 6 C atoms, preferably ethoxy, propoxy, butoxy or pentyloxy, very preferably ethoxy or propoxy.

[0237] Highly preferred are the compounds of formula III-2-1-3, III-2-1-4 and III-2-1-5.

[0238] In another preferred embodiment of the invention, the LC medium comprises one or more compounds of formula III selected from formulae III-3-1 and III-3-2

[0239]

[0240] wherein L 11 and L 12 have the same meaning as given under formula III, (O) represents O or a single bond,

[0241] R 33 represents an alkyl or alkenyl group having at most 7 C atoms, or the group Cy-C m H 2m+1 -,

[0242] m and n are the same or different and are 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1, and

[0243] Cy represents an alicyclic group having 3, 4 or 5 ring atoms, which is optionally substituted by an alkyl or alkenyl group each having at most 3 C atoms, or by a halogen or CN, and preferably represents cyclopropyl, cyclobutyl or cyclopentyl.

[0244] The compounds of formula III-3-1 and / or III-3-2 can replace the compounds of formula III-1 and / or III-2 or be additionally contained in the LC medium, preferably additionally.

[0245] Very preferred compounds of formula III-3-1 are as follows,

[0246]

[0247] where alkoxy represents a straight-chain alkoxy group having 1-6 C atoms.

[0248] Very preferred compounds of formula III-3-2 are as follows

[0249]

[0250] where alkoxy represents a straight-chain alkoxy group having 1-6 C atoms, preferably ethoxy, propoxy, butoxy or pentyloxy, very preferably ethoxy or propoxy.

[0251] In another preferred embodiment of the present invention, the LC medium comprises one or more compounds of formulae III-4 to III-6, preferably a compound of formula III-5,

[0252]

[0253] where the parameters have the meanings given above, R 11 preferably represents a straight-chain alkyl group and R 12 preferably represents an alkoxy group, each having 1-7 C atoms.

[0254] In another preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III, which are selected from the compounds of sub-formulae III-7 to III-9, preferably a compound of sub-formula III-8,

[0255]

[0256]

[0257] where the parameters have the meanings given above, R 11 preferably represents a straight-chain alkyl group and R 12Preferably represents an alkoxy group, each having 1 - 7 C atoms.

[0258] In another preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III, which are selected from sub-formula III-10,

[0259]

[0260] wherein R 31 and R 32 have the meanings given above.

[0261] Very preferably, the compounds of formula III-10 are selected from the following formulae,

[0262]

[0263]

[0264] wherein R 32 represents an alkyl group having 1 to 7 C atoms, preferably ethyl, n-propyl or n-butyl, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl, or alternatively -(CH 2 ) n F, where n is 2, 3, 4 or 5, preferably C 2 H 4 F.

[0265] In another preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III, which are selected from sub-formula III-11,

[0266]

[0267] wherein R 31 and R 32 have the meanings given above.

[0268] Very preferably, the compounds of formula III-11 are selected from the following formulae,

[0269]

[0270]

[0271] wherein R 32 represents an alkyl group having 1 to 7 C atoms, preferably ethyl, n-propyl or n-butyl, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl, or alternatively -(CH 2 ) n F, where n is 2, 3, 4 or 5, preferably C 2 H 4 F.

[0272] In a preferred embodiment, the LC medium comprises one or more compounds of formula IV,

[0273]

[0274] wherein

[0275] R 41 represents an unsubstituted alkyl group having 1 to 7 C atoms, wherein in addition, one or more CH 2 groups may be replaced by or an unsubstituted alkenyl group having 2 to 7 C atoms, preferably a normal alkyl group, particularly preferably having 2, 3, 4 or 5 C atoms, and

[0276] R 42 represents an unsubstituted alkyl group having 1 to 7 C atoms, or an unsubstituted alkoxy group having 1 to 6 C atoms (both preferably having 2 to 5 C atoms), an unsubstituted alkenyl group having 2 to 7 C atoms, preferably having 2, 3 or 4 C atoms, more preferably vinyl or 1-propenyl and particularly preferably vinyl.

[0277] The compounds of formula IV are preferably selected from the compounds of formulae IV-1 to IV-4,

[0278]

[0279] wherein

[0280] alkyl and alkyl’ independently of one another represent an alkyl group having 1 to 7 C atoms, preferably having 2 to 5 C atoms,

[0281] alkenyl represents an alkenyl group having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably 2 C atoms,

[0282] alkenyl ’ represents an alkenyl group having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms, and

[0283] alkoxy represents an alkoxy group having 1 to 5 C atoms, preferably having 2 to 4 C atoms.

[0284] Preferably, the LC medium comprises one or more compounds selected from the compounds of formulae IV-1-1 to IV-1-6

[0285]

[0286] Very preferably, the LC medium according to the invention comprises one or more compounds of formula IV-2-1 and / or IV-2-2

[0287]

[0288]

[0289] Very preferably, the LC medium according to the invention comprises a compound of formula IV-3, in particular a compound selected from the following sub-formulas:

[0290]

[0291]

[0292] In another preferred embodiment, the LC medium according to the invention comprises a compound of formula IV-3 which is one or more compounds selected from the following sub-formulas:

[0293]

[0294]

[0295]

[0296] wherein alkyl represents methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or n-pentyl.

[0297] Very preferably, the LC medium according to the invention comprises a compound of formula IV-4, in particular a compound selected from the following formulas:

[0298]

[0299]

[0300] In another preferred embodiment, the LC medium comprises one or more compounds of formula IV-4 and its sub-formulas, wherein

[0301] "alkenyl" and "alkenyl'" wherein

[0302] one or both of

[0303] m is 0, 1 or 2, and n is 0, 1 or 2, very preferably a compound selected from formulas IV-4-3 to IV-4-6.

[0304] Very preferably, the LC medium according to the invention comprises one or more compounds of formula IV-1 and its sub-formulas and / or one or more compounds of formula IV-3 and its sub-formulas and / or one or more compounds of formula IV-4 and its sub-formulas, wherein the total concentration of these compounds of formula IV-1 is in the range of 1% to 30%.

[0305] The LC medium according to the invention preferably additionally comprises one or more compounds of formula IVa,

[0306]

[0307] wherein

[0308] R 41 and R 42 each independently of one another represent a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkoxy having at most 12 C atoms,

[0309] represents

[0310]

[0311] Z 4 represents a single bond, -CH 2 CH 2 -, -CH=CH-, -CF 2 O-, -OCF 2 -, -CH 2 O-, -OCH 2 -, -COO-, -OCO-, -C 2 F 4 -, -C 4 H 8 - or -CF=CF-.

[0312] Preferred compounds of formula IVa are indicated below:

[0313]

[0314] where alkyl and alkyl* each independently of one another represent a straight-chain alkyl having 1-6 C atoms.

[0315] The LC medium according to the invention preferably comprises at least one compound of formula IVa-1 and / or of formula IVa-2.

[0316] The proportion of the compound of formula IVa in the overall mixture is preferably at least 5 wt%.

[0317] Preferably, the LC medium comprises one or more compounds of formulae IVb-1 to IVb-3

[0318]

[0319]

[0320] wherein

[0321] alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1 to 6 C atoms, and

[0322] alkenyl and alkenyl* each independently of one another represent a straight-chain alkenyl group having 2 to 6 C atoms.

[0323] The proportion of the compounds of formulae IV-1 to IV-3 in the overall mixture is preferably at least 3 wt%, in particular ≥ 5 wt%.

[0324] Among the compounds of formulae IVb-1 to IVb-3, the compound of formula IVb-2 is particularly preferred.

[0325] Particularly preferred compounds of formulae IV-1 to IV-3 are selected from the following formulae

[0326]

[0327] wherein alkyl* represents an alkyl group having 1 to 6 C atoms, preferably n-propyl.

[0328] The LC medium according to the invention particularly preferably comprises one or more compounds of formulae IVb-1-1 and / or IVb-2-3.

[0329] In another preferred embodiment, the LC medium according to the invention comprises one or more compounds of formula V

[0330]

[0331] wherein

[0332] R 51 and R 52 each independently of one another represent H, an alkyl, alkoxy or alkenyl group having at most 15 C atoms, which is unsubstituted, monosubstituted by F, Cl, CN or CF 3 or at least monosubstituted by halogen, wherein furthermore one or more CH 2 groups in these groups can be replaced by -O-, -S-, -C≡C-, -CF 2 O-, -OCF 2 -, -OC-O-, -O-CO-, and preferably represent an alkyl group having 1 to 7 C atoms, preferably a normal alkyl group, particularly preferably a normal alkyl group having 1 to 5 C atoms, an alkoxy group having 1 to 6 C atoms, preferably a normal alkoxy group, particularly preferably a normal alkoxy group having 2 to 5 C atoms, an alkoxyalkyl, alkenyl or alkenyloxy group having 2 to 7 C atoms, preferably an alkenyloxy group, identically or differently, represent

[0333]

[0334] wherein

[0335] preferably represents

[0336] Z 51 , Z 52 each independently of one another represents -CH 2 -CH 2 -, -CH 2 -O-, -CH=CH-, -C≡C-, -COO- or a single bond, preferably -CH 2 -CH 2 -, -CH 2 -O- or a single bond, and particularly preferably a single bond, and

[0337] n is 1 or 2.

[0338] The compound of formula V is preferably selected from the compounds of formulae V-1 to V-17:

[0339]

[0340]

[0341] wherein R 1 and R 2 have the meanings indicated above for R 51 and R 52 indicated.

[0342] R 1 and R 2 preferably each independently of one another represent a straight-chain alkyl or alkenyl group.

[0343] The preferred LC medium comprises one or more compounds of formulae V-1, V-3, V-4, V-6, V-7, V-10, V-11, V-12, V-14, V-15 and / or V-16.

[0344] The LC medium according to the invention very particularly preferably comprises a compound of formula V-10 and / or IV-1, in particular in an amount of 5-30%.

[0345] The preferred compound of formula V-10 is indicated below:

[0346]

[0347] The LC medium according to the invention particularly preferably comprises a combination of a tricyclic compound of formula V-10a and / or V-10b with one or more bicyclic compounds of formula IV-1. The total proportion of the compound of formula V-10a and / or V-10b in combination with one or more compounds selected from the bicyclohexyl compounds of formula IV-1 is 5-40%, very particularly preferably 15-35%.

[0348] A particularly preferred LC medium comprises the compound V-10a and / or IV-1-1

[0349]

[0350] Based on the overall mixture, the compounds V-10a and IV-1-1 are preferably present in the mixture at a concentration of 5 to 30%, very preferably 10 to 25%.

[0351] The preferred LC medium comprises at least one compound selected from the following compounds

[0352]

[0353] wherein R 1 , R 2 , R 41 and R 42 have the meanings indicated above. Preferably in the compounds V-6, V-7 and IV, R 1 and R 41 respectively represent an alkyl or alkenyl group having 1-6 or 2-6 C atoms, and R 2 and R 42 represent an alkenyl group having 2-6 C atoms. Preferably in the compound V-14, R 1 represents an alkyl or alkenyl group having 1-6 or 2-6 C atoms, and R 2 represents an alkyl group having 1-6 C atoms.

[0354] In another preferred embodiment, the LC medium according to the invention comprises one or more compounds of formula V-7, preferably selected from the compounds of formula V-7a to V-7e:

[0355]

[0356]

[0357] wherein alkyl represents an alkyl group having 1-7 C atoms, alkenyl represents an alkenyl group having 2-7 C atoms, and cycloalkyl represents a cyclic alkyl group having 3-12 C atoms, preferably cyclopropyl, cyclobutyl, cyclopentyl, cyclopropylalkyl, cyclobutylalkyl or cyclopentylalkyl.

[0358] The very preferred compounds of formulas V-7a to V-7e are selected from the compounds of the following sub-formulas:

[0359]

[0360]

[0361]

[0362]

[0363] wherein alkyl represents ethyl, n-propyl, n-butyl or n-pentyl, preferably n-propyl.

[0364] Further preferred are the compounds of formula V, wherein R 51 and R 52 each independently represent a straight-chain alkyl having 1-7 C atoms or an alkenyl having 2-7 C atoms.

[0365] In a preferred embodiment of the present invention, the LC medium additionally comprises one or more compounds of formulas VI-1 to VI-25,

[0366]

[0367]

[0368]

[0369]

[0370] wherein

[0371] R represents a straight-chain alkyl or alkoxy having 1-6 C atoms, (O) represents -O- or a single bond, X represents F, Cl, OCF 3 or OCHF 2 , L x represents H or F, m is 0, 1, 2, 3, 4, 5 or 6 and n is 0, 1, 2, 3 or 4.

[0372] R preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy.

[0373] X preferably represents F or OCH 3 , very preferably F.

[0374] The LC medium according to the present invention preferably comprises the terphenyls of formulas VI-1 to VI-25 in an amount of 2-30 wt%, in particular 5-20 wt%.

[0375] Particularly preferred are the compounds of formulae VI-1, VI-2, VI-4, VI-20, VI-21 and VI-22, where X represents F. Among these compounds, R preferably represents alkyl and alkoxy, each having 1 to 5 C atoms. In the compounds of formula VI-20, R preferably represents alkyl or alkenyl, especially alkyl. In the compounds of formula VI-21, R preferably represents alkyl. In the compounds of formulae VI-22 to VI-25, X preferably represents F.

[0376] If the Δn value of the mixture ≥ 0.1, the terphenyls of formulae VI-1 to VI-25 are preferably used in the LC medium according to the invention. The preferred LC medium contains 2 - 20 wt% of one or more terphenyl compounds selected from the compounds of formulae VI-1 to VI-25.

[0377] In another preferred embodiment of the invention, the LC medium additionally contains one or more compounds of formulae VII-1 to VII-9

[0378]

[0379] where

[0380] R 1 each independently of one another has one of the meanings indicated for R in formula IIA, and 21 w and x each independently of one another represent 1 to 6.

[0381] Particularly preferred is an LC medium containing at least one compound of formula VII-9.

[0382] The LC medium contains one or more substances containing a tetrahydronaphthyl or naphthyl unit, such as the compounds of formulae N-1 to N-5,

[0383] where R

[0384]

[0385] where R 61 and R 62 each independently of one another have the meaning indicated for R 21 and preferably represent straight-chain alkyl, straight-chain alkoxy or straight-chain alkenyl, and

[0386] Z 61 and Z 62 each independently of one another represent -C 2 H 4 -, -CH=CH-, -(CH 2 ) 4 -, -(CH 2 ) 3 O-, -O(CH 2 )3 -, -CH=CHCH 2 CH 2 -, -CH 2 CH 2 CH=CH-, -CH 2 O-, -OCH 2 -, -COO-, -OCO-, -C 2 F 4 -, -CF=CF-, -CF=CH-, -CH=CF-, -CF 2 O-, -OCF 2 -, -CH 2 - or a single bond.

[0387] c) an LC medium comprising one or more compounds selected from: a difluorodibenzochroman compound of formula BC, a chroman compound of formula CR, and fluorinated phenanthrene compounds of formulas PH-1 and PH-2,

[0388]

[0389] wherein

[0390] R 71 and R 72 each independently of one another have the meaning of R 21 and c is 0, 1 or 2. R 71 and R 72 preferably each independently of one another represent an alkyl or alkoxy group having 1-6 C atoms.

[0391] The LC medium according to the invention preferably comprises the compounds of formulas BC, CR, PH-1, PH-2 in an amount of from 3 to 20 wt%, in particular from 3 to 15 wt%.

[0392] Particularly preferred compounds of formulas BC and CR are compounds BC-1 to BC-7 and CR-1 to CR-5,

[0393]

[0394]

[0395]

[0396] wherein

[0397] alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1-6 C atoms, and

[0398] alkenyl and alkenyl* each independently of one another represent a straight-chain alkenyl group having 2-6 C atoms.

[0399] An LC medium very particularly preferably contains one, two or three compounds of formula BC-2, BF-1 and / or BF-2.

[0400] d) An LC medium containing one or more indane compounds of formula In,

[0401]

[0402] wherein

[0403] R 81 , R 82 , R 83 each independently of one another represents a straight-chain alkyl, alkoxy, alkoxyalkyl or alkenyl having 1 to 6 C atoms.

[0404] R 82 and R 83 may also represent halogen, preferably F,

[0405] represents

[0406]

[0407] i represents 0, 1 or 2.

[0408] Preferred compounds of formula In are the compounds of formulae In-1 to In-16 indicated below:

[0409]

[0410]

[0411] Particularly preferred are the compounds of formulae In-1, In-2, In-3 and In-4.

[0412] The compounds of formula In and sub-formulae In-1 to In-16 are preferably used in the LC media according to the invention in a concentration of ≥ 5 wt%, in particular 5 - 30 wt% and very particularly preferably 5 - 25 wt%.

[0413] e) An LC medium containing one or more compounds of formulae L-1 to L-8,

[0414]

[0415] wherein

[0416] R L1 to R L2 each independently of one another have the meanings indicated above for R 21 in formula IIA, alkyl represents an alkyl having 1 to 6 C atoms, and s represents 1 or 2.

[0417] The compounds of formulas L-1 to L-8 are preferably used at a concentration of 5 to 15 wt%, in particular 5 to 12 wt%, very particularly preferably 8 to 10 wt%.

[0418] f) The preferred LC medium additionally contains one or more compounds of formula IIA-Y

[0419]

[0420] wherein R 11 and R 12 have one of the meanings given above for R in formula IIA, L 21 and L 1 are the same or different and represent F or Cl. 2 The preferred compounds of formula IIA-Y are selected from the following sub-formulas

[0421] The preferred compounds of formula IIA-Y are selected from the following sub-formulas

[0422]

[0423]

[0424] wherein, Alkyl and Alkyl * each independently of one another represent a straight-chain alkyl group having 1-6 C atoms, Alkoxy represents a straight-chain alkoxy group having 1-6 C atoms, Alkenyl and Alkenyl * each independently of one another represent a straight-chain alkenyl group having 2-6 C atoms, and O represents an oxygen atom or a single bond. Alkenyl and Alkenyl * preferably represent CH 2 =CH-, CH 2 =CHCH 2 CH 2 -, CH 3 -CH=CH-, CH 3 -CH 2 -CH=CH-, CH 3 -(CH 2 ) 2 -CH=CH-, CH 3 -(CH 2 ) 3 -CH=CH- or CH 3 -CH=CH-(CH 2 ) 2 -.

[0425] The particularly preferred compounds of formula IIA-Y are selected from the following sub-formulas:

[0426]

[0427] wherein Alkoxy and Alkoxy * have the meanings defined above and preferably represent methoxy, ethoxy, n-propoxy, n-butoxy or n-pentyloxy.

[0428] g) an LC medium comprising one or more terphenyl compounds selected from the following formulas:

[0429]

[0430] wherein

[0431] R Q is an alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1-9 C atoms, or an alkenyl or alkenyloxy having 2-9 C atoms, all of which are optionally fluorinated,

[0432] X Q is F, Cl, a haloalkyl or alkoxy having 1-6 C atoms, or a haloalkenyl or alkenyloxy having 2-6 C atoms,

[0433] L Q1 -L Q6 are each independently H or F, where at least one of L Q1 -L Q6 is F.

[0434] Preferred compounds of formula Q are those in which R Q represents a straight-chain alkyl having 2-6 C atoms, very preferably ethyl, n-propyl or n-butyl.

[0435] Preferred compounds of formula Q are those in which L Q3 and L Q4 are F. Further preferred compounds of formula Q are those in which one or both of L Q1 and L Q2 and L Q3 , L Q4 are F.

[0436] Preferred compounds of formula Q are those in which X Q represents F or OCF 3 and is very preferably F.

[0437] Compounds of formula Q are preferably selected from the following sub-formulas

[0438]

[0439] wherein R Q has one of the meanings of formula Q, or one of its preferred meanings given above and below, and is preferably ethyl, n-propyl or n-butyl.

[0440] Particularly preferred are the compounds of formula Q1, especially those in which R Q is n-propyl.

[0441] Preferably, in the LC medium, the proportion of the compound of formula Q is >0 to ≤5% by weight, very preferably 0.05 to 2% by weight, more preferably 0.1 to 1% by weight, and most preferably 0.1 to 0.8% by weight.

[0442] Preferably, the LC medium contains 1 to 5, preferably 1 or 2 compounds of formula Q.

[0443] Adding the terphenyl compound of formula Q to the LC mixture of the polymerizable LC medium enables reduction of ODF non-uniformity while maintaining high UV absorption, which enables rapid and complete polymerization, enables strong and rapid tilt angle generation, and improves the UV stability of the LC medium.

[0444] Furthermore, adding a compound of formula Q having positive dielectric anisotropy to an LC medium having negative dielectric anisotropy allows better control of the dielectric constants ε || and ε ⊥ values, and particularly enables achieving a high dielectric constant ε || value while maintaining the dielectric anisotropy Δη constant, thereby reducing the kick-back voltage and reducing image retention.

[0445] The LC medium according to the invention preferably comprises

[0446] - one or more compounds of formula IA or its sub-formulas, preferably selected from sub-formulas IA1 to IA20, very preferably selected from sub-formulas IA3, IA8, IA13 and IA18, preferably at a concentration of 1 to 40%, very preferably 2 to 30%, most preferably 3 to 30% by weight,

[0447] and / or

[0448] - one or more compounds of formula IIA and / or IIB, preferably with a total concentration in the range of 30% to 65%, more preferably 35% to 60%, particularly preferably 40 to 55%;

[0449] and / or

[0450] - one or more compounds of formula IV, preferably with a total concentration in the range of 35% to 60%, more preferably 40% to 55%, particularly preferably 45% to 50%;

[0451] and / or

[0452] -One or more compounds of formula III, preferably a compound of formula III-2, very preferably a compound of formula III-2-1, preferably with a total concentration in the range of 2% to 25%, very preferably 4% to 15%;

[0453] and / or

[0454] -One or more compounds of formula III-3-2, preferably formula III-3-2-3 or III-3-2-4, preferably with a total concentration in the range of 2% to 25%, very preferably 4% to 15%,

[0455] and / or

[0456] -One or more compounds of formula III-10, preferably selected from formula III-10-1 to III-10-11, preferably with a total concentration in the range of 2% to 25%, very preferably 4% to 15%,

[0457] and / or

[0458] -One or more compounds of formula IID-1 and / or IID-4, preferably with a total concentration in the range of 0.5% to 15%, very preferably 0.5% to 8%,

[0459] and / or

[0460] -One or more compounds selected from formula IID-1, IID-15, IID-17, IID-18, IID-19, IID-20, IID-21, IID-22 and IID-23, very preferably selected from formula IID-1, IID-21, IID-22 and IID-23, preferably with a total concentration in the range of 0.5% to 15%, very preferably 0.5% to 8%.

[0461] In particular, the LC medium comprises

[0462] -One or more compounds CY-n-Om, in particular CY-3-O4, CY-5-O4 and / or CY-3-O2, preferably with a total concentration in the range of 5% to 30%, preferably 10% to 20% based on the total of the mixture,

[0463] -One or more compounds PY-n-Om, in particular PY-1-O2, PY-2-O2 and / or PY-3-O2, preferably with a total concentration in the range of 5% to 40%, preferably 10% to 30% based on the total of the mixture,

[0464] and / or

[0465] -One or more compounds CPY-n-Om, especially CPY-2-O2, CPY-3-O2 and / or CPY-5-O2, preferably at a concentration of >5%, especially 7% to 20% based on the total of the mixture;

[0466] and / or

[0467] -One or more compounds CCY-n-Om, preferably CCY-4-O2, CCY-3-O2, CCY-3-O3, CCY-3-O1 and / or CCY-5-O2, preferably at a concentration of >3%, especially 5 to 15% based on the total of the mixture,

[0468] and / or

[0469] -One or more compounds CPY-n-Om and CY-n-Om, preferably at a concentration of 10 to 80% based on the total of the mixture,

[0470] and / or

[0471] -One or more compounds CPY-n-Om and PY-n-Om, preferably CPY-2-O2 and / or CPY-3-O2 and PY-3-O2 or PY-1-O2, preferably at a concentration of 5 to 20%, more preferably 10 to 15% based on the total of the mixture,

[0472] and / or

[0473] -One or more compounds selected from CCH-13, CCH-23, CCH-34, CCH-35, CCH-301 and CCH-303, preferably with a total concentration of 3 to 40%, preferably 3 to 25% based on the total of the mixture,

[0474] and / or

[0475] -One or more compounds selected from CC-2-V1, CC-3-V1, CC-3-V2, CC-4-V1, CC-3-2V1, CC-3-V, CC-4-V, CC-5-V, CC-V-V, CC-V-V1, CC-1V-V1 and CC-2V-V2, preferably with a total concentration of 3 to 40%, more preferably 5% to 30% based on the total of the mixture,

[0476] and / or

[0477] -One or more compounds CCP-n-m and / or CCP-Vn-m and / or CPP-n-m, which are preferably selected from CCP-3-1, CCP-V-1, CCP-V2-1 and CPP-3-2, preferably with a total concentration of 4 to 35%, preferably 5 to 25% based on the total of the mixture,

[0478] and / or

[0479] - one or more compounds CLP-n-m and / or CLP-Vn-m, preferably selected from CLP-3-1, CLP-3-2 and CLP-V-1, preferably with a total concentration of 1 to 25%, preferably 2 to 15%, based on the overall mixture,

[0480] and / or

[0481] - one or more compounds PGP-n-m, preferably selected from PGP-2-3, PGP-2-4, PGP-2-5, PGP-3-5, preferably with a total concentration of 2 to 20%, more preferably 2% to 15%, most preferably 2 to 10%, based on the overall mixture,

[0482] and / or

[0483] - one or more compounds selected from PYP-n-m, PGIY-n-Om and PGP-n-2V, preferably selected from PGP-1-2V, PGP-2-2V and PGP-3-2V, preferably with a total concentration of 2 to 20%, more preferably 2% to 15%, most preferably 2 to 10%, based on the overall mixture,

[0484] and / or

[0485] - one or more compounds PP-n-m and / or PP-n-nVm, preferably selected from PP-1-3, PP-1-4, PP-1-5, PP-1-2V and PP-1-2V1, preferably with a total concentration of 1 to 15%, preferably 2 to 10% based on the overall mixture

[0486] and / or

[0487] - compound CCG-V-F, preferably with a concentration of 0.5% to 10% based on the overall mixture,

[0488] and / or

[0489] - compound PPGU-3-F, preferably with a concentration of 0.1% to 3% based on the overall mixture.

[0490] Advantageously, the liquid crystal medium according to the invention preferably has a nematic phase from ≤ -20 °C to ≥ 70 °C, particularly preferably from ≤ -30 °C to ≥ 80 °C, very particularly preferably from ≤ -40 °C to ≥ 90 °C.

[0491] The LC medium according to the invention preferably has a clearing temperature of 70 °C or higher, preferably 74 °C or higher.

[0492] Here, the expression "having a nematic phase" means on the one hand that no smectic phase and no crystallization are observed at low temperatures at the corresponding temperature, and on the other hand that no clearing occurs when heating from the nematic phase. The studies at low temperatures were carried out in a flow viscometer at the corresponding temperature and checked by storing in a test cell with a layer thickness corresponding to electro-optical applications for at least 100 hours. If the storage stability at a temperature of -20 °C in the corresponding test cell is 1000 hours or higher, the LC medium is said to be stable at this temperature. At temperatures of -30 °C and -40 °C, the corresponding times are 500 hours and 250 hours, respectively. At high temperatures, the clearing point was measured in a capillary by a conventional method.

[0493] The liquid crystal mixture preferably has a nematic range of at least 60 K and a flow viscosity ν of at most 30 mm 2 ·s -1 at 20 °C. 20 .

[0494] The mixture is nematic at a temperature of -20 °C or lower, preferably at -30 °C or lower, very preferably at -40 °C or lower.

[0495] The value of the birefringence Δn in the liquid crystal mixture is generally between 0.07 and 0.16, preferably between 0.075 and 0.14, very preferably between 0.075 and 0.12. In a preferred embodiment of the present invention, the LC medium has a birefringence in the range of 0.075 to 0.105.

[0496] The liquid crystal mixture according to the present invention has a dielectric anisotropy Δε of -1.5 to -8.0, in particular -2.0 to -5.0, in particular -2.5 to -4.8.

[0497] The rotational viscosity γ at 20 °C 1 is preferably ≤200 mPa·s, more preferably ≤180 mPa·s, very preferably ≤120 mPa·s, and most preferably ≤105 mPa·s. In another preferred embodiment, the rotational viscosity γ at 20 °C 1 is ≤100 mPa·s, in particular ≤95 mPa·s.

[0498] The liquid crystal medium according to the present invention has a relatively low threshold voltage (V 0 ). Their values are preferably in the range of 1.7 V to 3.0 V, particularly preferably ≤2.7 V and very particularly preferably ≤2.5 V.

[0499] For the present invention, unless otherwise explicitly stated, the term "threshold voltage" relates to the capacitive threshold also known as the Freedericks threshold (V 0 ).

[0500] Furthermore, the liquid crystal medium according to the present invention has a high voltage holding ratio value in a liquid crystal cell.

[0501] Typically, liquid crystal media with a low addressing voltage or threshold voltage exhibit a lower voltage holding ratio than those with a higher addressing voltage or threshold voltage, and vice versa.

[0502] For the present invention, the term "dielectrically positive compound" denotes a compound having Δε > 1.5, the term "dielectrically neutral compound" denotes those compounds having -1.5 ≤ Δε ≤ 1.5, and the term "dielectrically negative compound" denotes those compounds having Δε < -1.5. The dielectric anisotropy of the compounds is determined herein by dissolving 10% of the compound in a liquid crystal host and measuring the capacitance of the resulting mixture in at least one test cell having a layer thickness of 20 μm in each case, with homeotropic surface alignment and with planar surface alignment, at 1 kHz. The measuring voltage is typically 0.5 V to 1.0 V, but always below the capacitive threshold of the respective liquid crystal mixture under investigation.

[0503] All temperature values indicated in the present invention are in °C.

[0504] The LC media according to the present invention are suitable for all VA-TFT (vertical alignment thin film transistor) applications, for example, VAN (vertical alignment nematic), MVA (multi-domain VA), (S)-PVA (super patterned VA), ASV (advanced super view, or axially symmetric VA), PSA (polymer sustained VA) and PS-VA (polymer stabilized VA). They are also suitable for IPS (in-plane switching) and FFS (fringe field switching) applications with negative Δε.

[0505] The nematic LC media in the displays according to the present invention typically comprise two components A and B, which in turn consist of one or more individual compounds.

[0506] Component A has a significantly negative dielectric anisotropy and renders the dielectric anisotropy of the nematic phase ≤ -0.5. It preferably further comprises one or more of the compounds of formulae IIA, IIB, IIC and / or IID and, in addition, one or more compounds of formula III.

[0507] The proportion of component A is preferably between 45 and 100%, particularly between 60 and 85%.

[0508] For component A, it is preferred to select one (or more) single compounds having a Δε value of ≤ -1.5. The smaller the proportion A in the overall mixture, the more negative this value must be.

[0509] Component B has significant nematogeneity and a kinematic viscosity at 20 °C of not more than 30 mm 2 ·s -1 , preferably not more than 25 mm 2 ·s -1 .

[0510] A large number of suitable materials are known to the person skilled in the art from the literature. Compounds of formula IV are particularly preferred.

[0511] Particularly preferred single compounds in component B are very low viscosity nematic liquid crystals having a kinematic viscosity at 20 °C of not more than 18 mm 2 ·s -1 , preferably not more than 12 mm 2 ·s -1 .

[0512] Component B is monotropically or enantiotropically nematic, does not have a smectic phase, and is capable of preventing the appearance of a smectic phase in the LC medium at low to very low temperatures. For example, if various highly nematogenic materials are added to a smectic liquid crystal mixture, the nematogeneity of these materials can be compared by the degree of suppression of the smectic phase achieved.

[0513] The mixture may optionally further comprise component C, which comprises compounds having a dielectric anisotropy with Δε ≥ 1.5. These so-called positive compounds are generally present in the negative dielectric anisotropy mixture in an amount of ≤ 20% by weight based on the overall mixture.

[0514] In addition to one or more compounds of formula IA, the LC medium preferably comprises 4 to 15, in particular 5 to 12, and particularly preferably < 10 compounds of formula IIA, IIB, IIC and / or IID, and one or more compounds of formula IV.

[0515] In addition to the compounds of formula IA and the compounds of formula IIA, IIB, IIC and / or IID and / or IV, other components may also be present, in an amount of, for example, at most 45%, but preferably at most 35%, in particular at most 10% of the overall mixture.

[0516] The other components are preferably selected from nematic or nematogenic substances, in particular from known substances of the following categories: azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, phenyl benzoates or cyclohexyl benzoates, phenyl cyclohexanecarboxylates or cyclohexyl cyclohexanecarboxylates, phenylcyclohexanes, cyclohexylbiphenyls, cyclohexylcyclohexanes, cyclohexylnaphthalenes, 1,4-biscyclohexylbiphenyls or cyclohexylpyrimidines, phenyl dioxanes or cyclohexyl dioxanes, optionally halogenated benzyl phenyl ether, diphenylacetylene and substituted cinnamic acid esters.

[0517] The most important compounds suitable as components of a liquid crystal phase of this type can be represented by the formula R

[0518] R R1 -L-G-E-R R2 R

[0519] wherein L and E each represent a carbocyclic or heterocyclic ring system, the system being a group formed from: 1,4-disubstituted benzene and cyclohexane rings, 4,4'-disubstituted biphenyls, phenylcyclohexanes and cyclohexylcyclohexane systems, 2,5-disubstituted pyrimidines and 1,3-disubstituted alkane rings, 2,6-disubstituted naphthalenes, dihydronaphthalenes and tetrahydronaphthalenes, quinazolines and tetrahydroquinazolines,

[0520] G represents -CH=CH- -N(O)=N-

[0521] -CH=CQ- -CH=N(O)-

[0522] -C≡C- -CH 2 -CH 2 -

[0523] -CO-O- -CH 2 -O-

[0524] -CO-S- -CH 2 -S-

[0525] -CH=N- -COO-Phe-COO-

[0526] -CF 2 O- -CF=CF-

[0527] -OCF 2 - -OCH 2 -

[0528] -(CH 2 ) 4 - -(CH 2 ) 3 O-

[0529] or a C-C single bond,

[0530] Q represents a halogen, preferably chlorine, or -CN, and

[0531] R R1 and R R2 each represent an alkyl, alkenyl, alkoxy, alkoxyalkyl or alkoxycarbonyloxy group having at most 18, preferably at most 8 carbon atoms, or alternatively one of these groups represents CN, NC, NO 2 、NCS、CF 3 、SF 5 、OCF 3 、F、Cl or Br.

[0532] In most of these compounds, R R1 and R R2 are different from each other, and one of these groups is usually an alkyl or alkoxy group. Other variants of the proposed substituents are also common. Many such substances or their mixtures are commercially available. All these substances can be prepared by methods known from the literature.

[0533] It is self - evident to those skilled in the art that the VA, IPS or FFS mixtures according to the invention may also contain compounds in which, for example, H, N, O, Cl and F have been replaced by the corresponding isotopes.

[0534] The LC medium preferably has a nematic LC phase.

[0535] Preferably, the LC medium contains one or more polymerizable compounds, which are preferably selected from polymerizable mesogenic compounds, which are also referred to as "reactive mesogens" or RMs, and very preferably selected from formula M

[0536] R a -B 1 -(Z m -B 2 ) m -R b M

[0537] wherein each group, each time it occurs, is the same or different, and each is independent of one another, has the following meanings:

[0538] R a and R b represent P, P - Sp -, H, F, Cl, Br, I, -CN, -NO 2 、-NCO、-NCS、-OCN、-SCN、SF 5 or a straight - chain or branched - chain alkyl group having 1 to 25 C atoms, wherein in addition one or more non - adjacent CH 2The groups may also each independently of one another be replaced in such a way that O and / or S atoms are not directly linked to one another by -C(R 0 )=C(R 00 )-, -C≡C-, -N(R 00 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, and one or more H atoms may furthermore be replaced by F, Cl, Br, I, CN, P or P-Sp-, where if B 1 and / or B 2 contains saturated C atoms, R a and / or R b may also represent a group which is spiro-linked to this saturated C atom,

[0539] where at least one of the groups R a and R b represents or contains the group P or P-Sp-,

[0540] P represents a polymerizable group,

[0541] Sp represents a spacer group or a single bond,

[0542] B 1 and B 2 represent aromatic, heteroaromatic, cycloaliphatic or heterocyclic groups which preferably have 4 to 25 ring atoms, which groups may also contain fused rings and which are unsubstituted or mono- or polysubstituted by L,

[0543] Z m represents -O-, -S-, -CO-, -CO-O-, -OCO-, -O-CO-O-, -OCH 2 -, -CH 2 O-, -SCH 2 -, -CH 2 S-, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -, -(CH 2 ) n1 -, -CF 2 CH 2 -, -CH 2 CF 2 -, -(CF 2 ) n1 -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, -CH 2 CH 2-CO-O-, -O-CO-CH 2 -CH 2 -, -CR 0 R 00 - or a single bond,

[0544] R 0 and R 00 represent H or an alkyl group having 1 to 12 C atoms,

[0545] m represents 0, 1, 2, 3 or 4,

[0546] n1 represents 1, 2, 3 or 4,

[0547] L represents P, P-Sp-, OH, CH 2 OH, F, Cl, Br, I, -CN, -NO 2 , -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x ) 2 , -C(=O)Y 1 , -C(=O)R x , -N(R x ) 2 , an optionally substituted silyl group, an optionally substituted aryl group having 6 to 20 C atoms or a straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 25 C atoms, where one or more H atoms may also be replaced by F, Cl, P or P-Sp-,

[0548] Y 1 represents a halogen,

[0549] R x represents P, P-Sp-, H, a halogen, a straight-chain, branched or cyclic alkyl group having 1 to 25 C atoms, where in addition one or more non-adjacent CH 2 groups may also be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly linked to one another, and where in addition one or more H atoms may also be replaced by F, Cl, P or P-Sp-, an optionally substituted aryl or aryloxy group having 6 to 40 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 40 C atoms.

[0550] The polymerizable group P is a group suitable for polymerization reactions (such as free radical or ionic chain polymerization, addition polymerization or condensation polymerization) or for polymer-analogous transformation reactions (such as addition or condensation to the polymer backbone). Groups particularly preferred for chain polymerization are, in particular, those containing a C═C double bond or a -C≡C- triple bond, and groups suitable for polymerization in the case of ring opening, such as oxetane or epoxy groups.

[0551] Preferred groups P are selected from CH 2 =CW 1 -CO-O-, CH 2 =CW 1 -CO-, CH 2 =CW 2 -(O) k3 -, CW 1 =CH-CO-(O) k3 -, CW 1 =CH-CO-NH-, CH 2 =CW 1 -CO-NH-, CH 3 -CH═CH-O-, (CH 2 =CH) 2 CH-OCO-, (CH 2 =CH-CH 2 ) 2 CH-OCO-, (CH 2 =CH) 2 CH-O-, (CH 2 =CH-CH 2 ) 2 N-, (CH 2 =CH-CH 2 ) 2 N-CO-, HO-CW 2 W 3 -, HS-CW 2 W 3 -, HW 2 N-, HO-CW 2 W 3 -NH-, CH 2 =CW 1 -CO-NH-, CH 2 =CH-(COO) k1 -Phe-(O) k2 -, CH 2 =CH-(CO) k1 -Phe-(O) k2 -, Phe-CH═CH-, HOOC-, OCN- and W 4 W5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF 3 , phenyl or an alkyl group having 1 to 5 C atoms, especially H, F, Cl or CH 3 , W 2 and W 3 each independently of one another represents H or an alkyl group having 1 to 5 C atoms, especially H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently of one another represents Cl, an oxaalkyl group or an oxacarbonylalkyl group having 1 to 5 C atoms, W 7 and W 8 each independently of one another represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, which is optionally substituted by one or more groups L other than P-Sp- as defined above, k 1 , k 2 and k 3 each independently of one another represents 0 or 1, k 3 preferably represents 1, and k 4 represents an integer from 1 to 10.

[0552] The very preferred group P is selected from CH 2 =CW 1 -CO-O-, CH 2 =CW 1 -CO-, CH 2 =CW 2 -O-, CH 2 =CW 2 -, CW 1 =CH-CO-(O) k3 -, CW 1 =CH-CO-NH-, CH 2 =CW 1 -CO-NH-, (CH 2 =CH) 2 CH-OCO-, (CH 2 =CH-CH 2 ) 2 CH-OCO-, (CH 2 =CH) 2 CH-O-, (CH 2 =CH-CH 2 ) 2 N-, (CH 2 =CH-CH 2 ) 2N-CO-, CH 2 =CW 1 -CO-NH-, CH 2 =CH-(COO) k1 -Phe-(O) k2 -, CH 2 =CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH- and W 4 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF 3 , phenyl or an alkyl group having 1 to 5 C atoms, especially H, F, Cl or CH 3 , W 2 and W 3 each independently of one another represents H or an alkyl group having 1 to 5 C atoms, especially H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently of one another represents Cl, an oxaalkyl group or an oxacarbonylalkyl group having 1 to 5 C atoms, W 7 and W 8 each independently of one another represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, k 1 , k 2 and k 3 each independently of one another represents 0 or 1, k 3 preferably represents 1, and k 4 represents an integer from 1 to 10.

[0553] A very particularly preferred group P is selected from CH 2 =CW 1 -CO-O-, especially CH 2 =CH-CO-O-, CH 2 =C(CH 3 )-CO-O- and CH 2 =CF-CO-O-, and also CH 2 =CH-O-, (CH 2 =CH) 2 CH-O-CO-, (CH 2 =CH) 2 CH-O-,

[0554] Further preferably, the polymerizable group P is selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, and most preferably from acrylate and methacrylate.

[0555] Very preferably, all polymerizable groups in the polymerizable compound have the same meaning.

[0556] If the spacer group Sp is not a single bond, it is preferably a spacer group of the formula Sp"-X", so that the corresponding group P-Sp- conforms to the formula P-Sp"-X"-, where

[0557] Sp" represents a straight-chain or branched alkylene group 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 furthermore one or more non-adjacent CH 2 groups can also each independently of one another be replaced by -O-, -S-, -NH-, -N(R 0 )-, -Si(R 0 R 00 )-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -S-CO-, -CO-S-, -N(R 00 )-CO-O-, -O-CO-N(R 0 )-, -N(R 0 )-CO-N(R 00 )-, -CH=CH- or -C≡C- in such a way that O and / or S atoms are not directly linked to one another,

[0558] X" represents -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CO-N(R 0 )-, -N(R 0 )-CO-, -N(R 0 )-CO-N(R 00 )-, -OCH 2 -, -CH 2 O-, -SCH 2 -, -CH 2 S-, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -, -CF 2 CH 2 -, -CH 2 CF 2 -, -CF 2 CF 2-, -CH=N-, -N=CH-, -N=N-, -CH=CR 0 -, -CY 2 =CY 3 -, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH- or a single bond,

[0559] R 0 and R 00 each independently of one another represent H or an alkyl group having 1 to 20 C atoms, and

[0560] Y 2 and Y 3 each independently of one another represent H, F, Cl or CN.

[0561] X" is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -, -NR 0 -, -CO- 0 -, -CO-NR 00 - or a single bond.

[0562] Typical spacer groups Sp and -Sp"-X"- are for example -(CH 2 ) p1 -, -(CH 2 ) p1 -O-, -(CH 2 ) p1 -O-CO-, -(CH 2 ) p1 -CO-O-, -(CH 2 ) p1 -O-CO-O-, -(CH 2 CH 2 O) q1 -CH 2 CH 2 -, -CH 2 CH 2 -S-CH 2 CH 2 -, -CH 2 CH 2 -NH-CH 2 CH 2 - or -(SiR 0 R 00 -O) p1 -, where p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R 0 and R 00 have the meanings indicated above.

[0563] Particularly preferred groups Sp and -Sp"-X"- are -(CH 2 ) p1 -, -(CH 2 ) p1 -O-, -(CH 2 ) p1 -O-CO-, -(CH 2 ) p1 -CO-O-, -(CH 2 ) p1 -O-CO-O-, where p1 and q1 have the meanings indicated above.

[0564] 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, ethyl-N-methyliminoethylene, 1-methylalkylene, vinyl, propenyl and butenyl.

[0565] In a preferred embodiment of the invention, the polymerizable compound contains a spacer group Sp which is substituted by one or more polymerizable groups P such that the group Sp-P corresponds to Sp(P) s , where s is ≥ 2 (branched polymerizable groups).

[0566] Preferred polymerizable compounds according to this preferred embodiment are those in which s is 2, i.e. compounds containing the group Sp(P) 2 . Very preferred polymerizable compounds according to this preferred embodiment contain a group selected from the following formulae:

[0567] -X-alkyl-CHPP S1

[0568] -X-alkyl-CH((CH 2 ) aa P)((CH 2 ) bb P) S2

[0569] -X-N((CH 2 ) aa P)((CH 2 ) bb P) S3

[0570] -X-alkyl-CHP-CH 2 -CH 2 P S4

[0571] -X-alkyl-C(CH2 P)(CH 2 P)-C aa H 2aa+1 S5

[0572] -X-alkyl-CHP-CH 2 P S6

[0573] -X-alkyl-CPP-C aa H 2aa+1 S7

[0574] -X-alkyl-CHPCHP-C aa H 2aa+1 S8

[0575] wherein P is as defined in formula M,

[0576] alkyl represents a single bond or a straight-chain or branched alkylene group having 1 to 12 C atoms, which is unsubstituted or mono- or polysubstituted by F, Cl or CN, and wherein one or more non-adjacent CH 2 groups may each independently of one another be replaced by -C(R 0 )=C(R 0 )-, -C≡C-, -N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly linked to one another, where R 0 has the meaning indicated above,

[0577] aa and bb each independently of one another represent 0, 1, 2, 3, 4, 5 or 6,

[0578] X has one of the meanings indicated for X", and is preferably O, CO, SO 2 , O-CO-, CO-O or a single bond.

[0579] Preferred spacer group Sp(P) 2 is selected from formulae S1, S2 and S3.

[0580] Very preferred spacer group Sp(P) 2 is selected from the following sub-formulae:

[0581] -CHPP S1a

[0582] -O-CHPP S1b

[0583] -CH 2 -CHPP S1c

[0584] -OCH 2 -CHPP S1d

[0585] -CH(CH 2 -P)(CH 2 -P) S2a

[0586] -OCH(CH 2 -P)(CH 2 -P) S2b

[0587] -CH 2 -CH(CH 2 -P)(CH 2 -P) S2c

[0588] -OCH 2 -CH(CH 2 -P)(CH 2 -P) S2d

[0589] -CO-NH((CH 2 ) 2 P)((CH 2 ) 2 P) S3a

[0590] P is preferably selected from ethenyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, very preferably from acrylate and methacrylate, and most preferably from methacrylate.

[0591] Further preferably, all polymerizable groups P present in the same compound have the same meaning, and very preferably represent acrylate or methacrylate, and most preferably methacrylate.

[0592] Sp preferably represents a single bond or -(CH 2 ) p1 -, -(CH 2 ) p2 -CH=CH-(CH 2 ) p3 -, -O-(CH 2 ) p1 -, -O-CO-(CH 2 ) p1 or -CO-O-(CH 2 ) p1 , where p1 is 2, 3, 4, 5 or 6, preferably 2 or 3, p2 and p3 are independently of each other 0, 1, 2 or 3, and if Sp is -O-(CH 2 ) p1 -, -O-CO-(CH 2 ) p1 or -CO-O-(CH 2 )p1 , the O atom or the CO group is respectively connected to the benzene ring.

[0593] More preferably, at least one group Sp is a single bond.

[0594] More preferably, at least one group Sp is not a single bond and is preferably selected from -(CH 2 ) p1 -, -(CH 2 ) p2 -CH=CH-(CH 2 ) p3 -, -O-(CH 2 ) p1 -, -O-CO-(CH 2 ) p1 or -CO-O-(CH 2 ) p1 , where p1 is 2, 3, 4, 5 or 6, preferably 2 or 3, p2 and p3 are independently of each other 0, 1, 2 or 3, and if Sp is -O-(CH 2 ) p1 -, -O-CO-(CH 2 ) p1 or -CO-O-(CH 2 ) p1 , the O atom or the CO group is respectively connected to the benzene ring.

[0595] Very preferably, Sp is not a single bond and is selected from -(CH 2 ) 2 -, -(CH 2 ) 3 -, -(CH 2 ) 4 -, -O-(CH 2 ) 2 -, -O-(CH 2 ) 3 -, -O-CO-(CH 2 ) 2 and -CO-O-(CH) 2 (-), where the O atom or the CO group is connected to the benzene ring.

[0596] Particularly preferred compounds of formula M are those compounds in which B 1 and B 2Each independently represents 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl, naphthalene-2,6-diyl, phenanthrene-2,7-diyl, 9,10-dihydrophenanthrene-2,7-diyl, anthracene-2,7-diyl, fluorene-2,7-diyl, coumarin, flavone, wherein one or more CH groups in these groups may further be replaced by N, cyclohexane-1,4-diyl, wherein one or more non-adjacent CH 2 groups may further be replaced by O and / or S, 1,4-cyclohexenylene, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, piperidine-1,4-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, indane-2,5-diyl or octahydro-4,7-methanoindane-2,5-diyl, and all of these groups may be unsubstituted or mono- or polysubstituted by L as defined above.

[0597] Particularly preferred compounds of formula M are those compounds in which B 1 and B 2 each independently represent 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl.

[0598] Further preferred compounds of formula M are those compounds in which the group -B 1 -(Z m -B 2 ) m - is selected from the following formulas

[0599]

[0600] wherein at least one benzene ring is substituted by at least one group L, and the benzene ring is optionally further substituted by one or more groups L or P-Sp-.

[0601] Preferred compounds of formula M and its sub-formulas are selected from the following preferred embodiments, including any combination thereof:

[0602] — All groups P in the compound have the same meaning,

[0603] — -B 1 -(Z m -B 2 ) m - is selected from formulas A1, A2 and A5,

[0604] — The compound exactly contains two polymerizable groups (represented by group P),

[0605] — The compound exactly contains three polymerizable groups (represented by group P),

[0606] — P is selected from acrylate, methacrylate and oxetane, very preferably acrylate or methacrylate,

[0607] — P is methacrylate,

[0608] — All groups Sp are single bonds,

[0609] — At least one of the groups Sp is a single bond and at least one of the groups Sp is not a single bond,

[0610] — Sp, when not a single bond, is -(CH 2 ) p2 -, -(CH 2 ) p2 -O-, -(CH 2 ) p2 -CO-O-, -(CH 2 ) p2 -O-CO-, where p2 is 2, 3, 4, 5 or 6, and the O atom or the CO group is respectively connected to the benzene ring,

[0611] — Sp is a single bond or represents -(CH 2 ) p2 -, -(CH 2 ) p2 -O-, -(CH 2 ) p2 -CO-O-, -(CH 2 ) p2 -O-CO-, where p2 is 2, 3, 4, 5 or 6, and the O atom or the CO group is respectively connected to the benzene ring,

[0612] — R represents P-Sp-,

[0613] — R does not represent or contain a polymerizable group,

[0614] — R does not represent or contain a polymerizable group, and represents a straight-chain, branched-chain or cyclic alkyl group having 1 to 25 C atoms, where one or more non-adjacent CH 2 groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and / or S atoms are not directly connected to each other, and where one or more H atoms are each optionally replaced by F, Cl or L a replacement,

[0615] — L or L' represents F, Cl or CN,

[0616] — L is F.

[0617] The very preferred compounds of formula M are selected from the following formulas:

[0618]

[0619]

[0620]

[0621]

[0622]

[0623] wherein each group, each time it appears, is the same or different and each is independent of the others and has the following meanings:

[0624] P 1 、P 2 、P 3 represents a polymerizable group which is preferably selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy group, very preferably acrylate or methacrylate,

[0625] Sp 1 、Sp 2 、Sp 3 represents a single bond or a spacer group, wherein in addition one or more groups P 1 -Sp 1 -、P 2 -Sp 2 - and P 3 -Sp 3 - may also represent R M provided that at least one of the groups P 1 -Sp 1 -、P 2 -Sp 2 and P 3 -Sp 3 - is not R M which preferably has one of the preferred meanings of Sp given above, very preferably -(CH 2 ) p1 -、-(CH 2 ) p1 -O-、-(CH 2 ) p1 -CO-O- or -(CH 2 ) p1 -O-CO-O-, where p1 is an integer from 1 to 12,

[0626] R Mrepresents H, F, Cl, CN or a straight-chain or branched alkyl group having 1 to 25 C atoms, wherein in addition one or more non-adjacent CH 2 groups may also each independently of one another be replaced by -C(R 0 )=C(R 00 )-, -C≡C-, -N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly linked to one another, and wherein in addition one or more H atoms may also be replaced by F, Cl, CN or P 1 -Sp 1 -, particularly preferably a straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 12 C atoms (wherein the alkenyl and alkynyl groups have at least two C atoms and the branched groups have at least three C atoms), and wherein R aa does not represent or contain the group P 1 , P 2 or P 3 ,

[0627] R 0 , R 00 represents H or an alkyl group having 1 to 12 C atoms,

[0628] R y and R z represent H, F, CH 3 or CF 3 ,

[0629] X 1 , X 2 , X 3 represent -CO-O-, -O-CO- or a single bond,

[0630] Z M1 represents -O-, -CO-, -C(R y R z )- or -CF 2 CF 2 -,

[0631] Z M2 , Z M3 represent -CO-O-, -O-CO-, -CH 2 O-, -OCH 2 -, -CF 2 O-, -OCF 2 -, or -(CH 2 ) n -, where n is 2, 3 or 4,

[0632] L represents F, Cl, CN or a linear or branched, optionally mono- or polyfluorinated, alkyl, alkoxy, thioalkyl, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 12 C atoms,

[0633] L', L" represent H, F or Cl,

[0634] k represents 0 or 1,

[0635] r represents 0, 1, 2, 3 or 4,

[0636] s represents 0, 1, 2 or 3,

[0637] t represents 0, 1 or 2,

[0638] x represents 0 or 1.

[0639] Compounds of the formulae M2, M13 and M32 are very preferably used, in particular those which exactly contain two polymerizable groups P 1 and P 2 and are di-reactive compounds.

[0640] Compounds selected from the formulae M17 to M31 are further preferably used, in particular those selected from the formulae M20, M22, M26, M29 and M31, in particular those which exactly contain three polymerizable groups P 1 , P 2 and P 3 and are tri-reactive compounds.

[0641] In the compounds of the formulae M1 to M32, the group

[0642] is preferably

[0643]

[0644] wherein L, each time it occurs, is the same or different and has one of the meanings given above and below, and is preferably F, Cl, CN, NO 2 , CH 3 , C 2 H 5 , C(CH 3 ) 3 , CH(CH 3 ) 2 , CH 2 CH(CH 3 )C 2 H 5 , -CH=CH 2 , C(CH 3)=CH 2 、SCH 3 、OCH 3 、OC 2 H 5 、COCH 3 、COC 2 H 5 、COOCH 3 、COOC 2 H 5 、CF 3 、OCF 3 、OCHF 2 、OC 2 F 5 or P-Sp-, very preferably F, Cl, CN, CH 3 、C 2 H 5 、-CH=CH 2 、C(CH 3 )=CH 2 、SCH 3 、OCH 3 、COCH 3 、OCF 3 or P-Sp-, more preferably F, Cl, CH 3 、-CH=CH 2 、C(CH 3 )=CH 2 、SCH 3 、OCH 3 、COCH 3 or OCF 3 , most preferably F, SCH 3 or OCH 3 。

[0645] Preferred compounds of formulas M1 to M32 are those compounds in which P 1 、P 2 and P 3 represent acrylate, methacrylate, oxetane or epoxy groups, very preferably acrylate or methacrylate groups, and most preferably methacrylate groups.

[0646] Further preferred compounds of formulas M1 to M32 are those compounds in which Sp 1 、Sp 2 and Sp 3 is a single bond.

[0647] Further preferred compounds of formulas M1 to M32 are those compounds in which Sp 1 、Sp 2 and Sp 3One of them is a single bond, while Sp 1 、Sp 2 and Sp 3 the other one is not a single bond.

[0648] Further preferred compounds of formulas M1 to M32 are those compounds in which the groups Sp 1 、Sp 2 and Sp 3 represent -(CH 2 ) s1 -X"-, where s1 is an integer from 1 to 6, preferably 2, 3, 4 or 5, and X" is a bond connecting to the benzene ring and is -O-, -O-CO-, -CO-O-, -O-CO-O- or a single bond.

[0649] Further preferred polymerizable compounds are selected from Table E below, especially selected from formulas 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.

[0650] Particularly preferred is an LC medium containing one, two or three polymerizable compounds of formula M.

[0651] Further preferred is an LC medium containing two or more di-reactive polymerizable compounds of formula M, the formula M is preferably selected from formulas M1 to M16 and M32, very preferably selected from formulas M2, M13 and M32.

[0652] Further preferred is an LC medium containing one or more di-reactive polymerizable compounds of formula M, the formula M is preferably selected from formulas M1 to M16 and M32, very preferably selected from formulas M2, M13 and M32, and one or more tri-reactive polymerizable compounds of formula M, the formula M is preferably selected from formulas M17 to M32, very preferably selected from formulas M20, M22, M26, M29 and M31.

[0653] Further preferred is an LC medium comprising one or more polymerizable compounds of formula M, where at least one r is not 0, or at least one of s and t is not 0, said formula M being very preferably selected from formulae M2, M13, M22, M24, M27, M29, M31 and M32, and where L is selected from the preferred groups shown above, most preferably selected from F, OCH 3 and SCH 3 .

[0654] Further preferred is an LC medium comprising one or more polymerizable compounds which exhibit absorption in the wavelength range from 320 to 380 nm, preferably selected from formula M, very preferably selected from formulae M1 to M32.

[0655] Particularly preferred is an LC medium comprising one, two or three polymerizable compounds selected from formula M or formulae M1 to M32.

[0656] The compounds of the preferred embodiments mentioned above in combination with the polymeric compounds described above and below result in a low threshold voltage, a low rotational viscosity and very good low-temperature stability in the LC media according to the invention, while resulting in a constant high clearing point and a high HR value and allowing a particularly low tilt angle (i.e., large tilt) to be established quickly in PSA displays. In particular, the LC media, compared to LC media of the prior art, exhibit a significantly shortened response time, especially also the gray-scale response time, in PSA displays.

[0657] For use in PSA displays, the total proportion of the polymerizable compounds (such as those of formula M or M1 to M32) in the LC medium is preferably from 0.01 to 2.0%, very preferably from 0.1 to 1.0%, and most preferably from 0.2 to 0.8%.

[0658] For use in SA-VA displays, the total proportion of the polymerizable compounds (such as those of formula M or M1 to M32) in the LC medium is preferably >0 to <3%, very preferably >0 to <2%, more preferably 0.05 to 2.0, and most preferably 0.05 to 1.0%.

[0659] The compounds of formula M and its sub-formulae can be prepared analogously to methods known to those skilled in the art and described in standard works of organic chemistry (for example in Houben-Weyl, Methoden der organischen Chemie (Methods of Organic Chemistry), Thieme-Verlag, Stuttgart).

[0660] For example, acrylates or methacrylates can be prepared by esterifying the corresponding alcohols with acid derivatives such as (meth)acryloyl chloride or (meth)acrylic anhydride in the presence of, for example, pyridine or triethylamine and 4-(N,N-dimethylamino)pyridine (DMAP). Alternatively, the esters can be prepared by esterifying the alcohols with (meth)acrylic acid in the presence of a dehydrating reagent, for example, by esterification according to Steglich with dicyclohexylcarbodiimide (DCC), N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) or N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and DMAP.

[0661] The invention also relates to an LC medium or an LC display as described above, in which polymerizable compounds such as those of formula M and its sub-formulae are present in polymerized form.

[0662] Optionally, one or more polymerization initiators are added to the LC medium. Suitable polymerization conditions as well as suitable types and amounts of initiators are known to those skilled in the art and are described in the literature. Suitable radical polymerizations are, for example, commercially available photoinitiators or (Ciba AG). If a polymerization initiator is used, its proportion is preferably from 0.001 to 5% by weight, particularly preferably from 0.001 to 1% by weight.

[0663] The polymerizable compounds according to the invention are also suitable for polymerization without an initiator, which has considerable advantages such as, for example, lower material costs and, in particular, less contamination of the LC medium by possible residual amounts of the initiator or its degradation products. Thus, the polymerization can also be carried out without the addition of an initiator. In a preferred embodiment, the LC medium is thus free of polymerization initiators.

[0664] The LC medium may further comprise one or more stabilizers to prevent the RM from undergoing unwanted spontaneous polymerization, for example, during storage or transportation. Suitable types and amounts of stabilizers are known to those skilled in the art and are described in the literature. Particularly suitable are, for example, commercially available stabilizers from the series (Ciba AG), such as 1076. If stabilizers are used, their proportion based on the total amount of RM or polymerizable components (component A) is preferably from 10 - 50,000 ppm, particularly preferably from 50 - 5,000 ppm.

[0665] In a preferred embodiment, the LC medium contains one or more chiral dopants, preferably at a concentration of 0.01 to 1 wt%, very preferably 0.05 to 0.5 wt%. The chiral dopant is preferably selected from the compounds of Table C below, very preferably selected from R- or S-1011, R- or S-2011, R- or S-3011, R- or S-4011, and R- or S-5011.

[0666] In another preferred embodiment, the LC medium contains a racemate of one or more chiral dopants, the chiral dopant preferably being selected from the chiral dopants mentioned in the previous paragraph.

[0667] In another preferred embodiment of the present invention, the LC medium contains one or more additional stabilizers.

[0668] Preferred stabilizers are selected from the compounds of formula H

[0669]

[0670] where

[0671] Ar represents an aromatic or heteroaromatic hydrocarbon group having 4 to 40 C atoms, preferably 6 to 30 C atoms;

[0672] Sp represents a spacer group;

[0673] R S represents H, an alkyl group having 1 to 12 C atoms, or an alkenyl group having 2 to 12 C atoms;

[0674] Z S represents -O-, -C(O)O-, -(CH 2 ) z -, or -(CH 2 ) z O-, or a single bond,

[0675] HA represents

[0676] R H represents H, O·, CH 3 , OH, or OR S , preferably H or O·;

[0677] R S1 , R S2 , R S3 and R S4 are the same or different and represent an alkyl group having 1 to 6 C atoms, preferably having 1 to 3 C atoms, very preferably CH 3 ;

[0678] G represents H or RS or group Z S -HA;

[0679] z is an integer from 1 to 6; and

[0680] q is 3 or 4.

[0681] Compounds of formula H are described in EP3354710 A1 and EP3354709 A1.

[0682] Preferred compounds of formula H are selected from formulae H-1, H-2 and H-3:

[0683]

[0684]

[0685] wherein R H has the meaning given above and preferably represents H or O·, and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7, and Sp represents a spacer group, preferably an alkylene group having 1 to 12 C atoms, wherein one or more non-adjacent -CH 2 - groups may be replaced by -O-.

[0686] Preferred compounds of formula H-1 are those compounds of formula H-1-1:

[0687]

[0688] wherein R H has the meaning given above and preferably represents H or O·, and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0689] Very preferred compounds of formula H-1-1 are those compounds of formula H-1-1-1:

[0690]

[0691] Preferred compounds of formula H-2 are those compounds of formula H-2-1:

[0692]

[0693] wherein R H has the meaning given above and preferably represents H or O·, and n2, each occurrence being the same or different, preferably the same, is an integer from 1 to 12, preferably 2, 3, 4, 5 or 6, very preferably 3, and R S each occurrence being the same or different, preferably the same, represents an alkyl group having 1 to 6 C atoms, preferably n-butyl.

[0694] Highly preferred compounds of formula H-2-1 are those of formula H-2-1-1:

[0695]

[0696] Preferred compounds of formula H-3 are selected from formula H-3-1:

[0697]

[0698] wherein Sp and R H have the meanings given above, and R H preferably represents H or O·, and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, and very preferably 7.

[0699] Also preferred stabilizers are selected from formulas ST-1 to ST-18:

[0700]

[0701]

[0702]

[0703] wherein

[0704] R ST represents H, an alkyl or alkoxy group having 1 to 15 C atoms, wherein in addition one or more CH 2 groups can also each independently of one another be replaced by -C≡C-, -CF 2 O-, -OCF 2 -, -CH=CH-,

[0705] -O-, -CO-O-, -O-CO- in such a way that the O atoms are not directly linked to one another, and wherein one or more H atoms can also be replaced by halogen,

[0706] represents the same or different in each occurrence

[0707]

[0708] Z ST each independently of one another represents -CO-O-, -O-CO-, -CF 2 O-, -OCF 2 -, -CH 2 O-, -OCH 2 -, -CH 2 -, -CH 2 CH 2 -,-(CH2 ) 4 -, -CH=CH-, -CH 2 O-, -C 2 F 4 -, -CH 2 CF 2 -, -CF 2 CH 2 -, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond,

[0709] L 1 and L 2 each independently of one another represents F, Cl, CH 3 , CF 3 or CHF 2 ,

[0710] p represents 0, 1 or 2,

[0711] q represents 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0712] Preferred compounds of formula ST are those compounds selected from formula ST-3, and in particular:

[0713]

[0714] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3

[0715]

[0716] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3

[0717]

[0718] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 1

[0719] or 7

[0720]

[0721]

[0722] In the compounds of formula ST-3a and ST-3b, n preferably represents 3. In the compounds of formula ST-2a, n preferably represents 7.

[0723] Very preferred stabilizers are selected from the compounds of formula ST-2a-1, ST-3a-1, ST-3b-1, ST-8-1, ST-9-1 and ST-12:

[0724]

[0725]

[0726] In another preferred embodiment, the LC medium comprises one or more stabilizers selected from Table D below.

[0727] Preferably, in the LC medium, the proportion of the stabilizer is 10 to 500 ppm, very preferably 20 to 100 ppm.

[0728] In another preferred embodiment, the LC medium according to the present invention contains a self-alignment (SA) additive, preferably at a concentration of 0.1 to 2.5%.

[0729] In a preferred embodiment, the SA-VA display according to the present invention does not contain a polyimide alignment layer. In another preferred embodiment, the SA-VA display according to the preferred embodiment contains a polyimide alignment layer.

[0730] The preferred SA additives for use in this preferred embodiment are selected from compounds comprising a mesogenic group and a linear or branched alkyl side chain, the alkyl side chain being terminated by one or more polar anchoring groups selected from hydroxyl, carboxyl, amino or thiol groups.

[0731] More preferably, the SA additive contains one or more polymerizable groups, which are optionally linked to the mesogenic group via a spacer group. These polymerizable SA additives can be polymerized in the LC medium under conditions similar to those applied to the RM in the PSA process.

[0732] Suitable SA additives for inducing vertical alignment, especially those used in SA-VA mode displays, are disclosed, for example, in US 2013 / 0182202 A1, US 2014 / 0838581 A1, US 2015 / 0166890 A1 and US2015 / 0252265 A1.

[0733] In another preferred embodiment, the LC medium or polymer-stabilized SA-VA display according to the present invention contains one or more self-alignment additives selected from Table F below.

[0734] In another preferred embodiment, the LC medium according to the present invention contains one or more SA additives, preferably selected from Formula II or its sub-formulas or from Table F below, at a concentration of 0.1 to 5%, very preferably 0.2 to 3%, and most preferably 0.2 to 1.5%.

[0735] The invention further relates to an LC display comprising an LC medium according to the invention as described above and below, which is preferably a PSA or SA display, very preferably a PS-VA, PS-IPS, PS-FFS or SA-VA display.

[0736] The invention further relates to an LC display comprising an LC medium as described above and below, wherein the polymerizable compound is present in polymerized form, and the LC display is preferably a PSA or SA display, very preferably a PS-VA, PS-IPS, PS-FFS or SA-VA display.

[0737] To prepare a PSA or polymer-stabilized SA display, the polymerizable compound comprised in the LC medium is polymerized in situ in the LC medium between the substrates of the LC display, preferably while applying a voltage to the electrodes.

[0738] The structure of the display according to the invention corresponds to the usual geometry of a PSA display, as described in the prior art cited at the beginning. A geometry without protrusions is preferred, in particular those shapes in which the electrode on the color filter side is unstructured and only the electrode on the TFT side has grooves. A particularly suitable and preferred electrode structure for a PS-VA display is described, for example, in US2006 / 0066793 A1.

[0739] The preferred PSA-type LC display of the invention comprises:

[0740] - a first substrate comprising pixel electrodes defining pixel regions, the pixel electrodes being connected to switching elements provided in each pixel region and optionally comprising a micro-slit pattern, and optionally a first alignment layer provided on the pixel electrodes,

[0741] - a second substrate comprising a common electrode layer which may be provided over the entire portion of the second substrate facing the first substrate and optionally a second alignment layer,

[0742] - an LC layer provided between the first and second substrates and comprising an LC medium as described above and below, wherein the polymerizable compound may also be present in polymerized form.

[0743] The first and / or second alignment layer controls the alignment direction of the LC molecules of the LC layer. For example, in a PS-VA display, the alignment layer is selected such that it imparts a homeotropic (or vertical) alignment (i.e., perpendicular to the surface) or an inclined alignment to the LC molecules. Such an alignment layer may, for example, comprise polyimide, which may also be rubbed, or may be prepared by a photo-alignment method.

[0744] The LC layer with the LC medium can be deposited between the substrates of the display by methods commonly used by display manufacturers, such as the so-called drop-down injection (ODF) method. Then the polymerizable components of the LC medium are polymerized, for example, by UV photopolymerization. The polymerization can be carried out in one step or in two or more steps.

[0745] The PSA display may include additional elements, such as color filters, black matrices, passivation layers, optical retardation layers, transistor elements for addressing individual pixels, etc., all of which are well known to those skilled in the art and can be used without creative skills.

[0746] Those skilled in the art can design the electrode structure according to the individual display type. For example, for a PS-VA display, the multi-domain orientation of the LC molecules can be induced by providing electrodes having slits and / or bumps or protrusions to create two, four or more different tilt alignment directions.

[0747] When polymerized, the polymerizable compound forms a copolymer, which results in a specific tilt angle of the LC molecules in the LC medium. Without wishing to be bound by a particular theory, it is believed that at least a portion of the crosslinked polymer formed from the polymerizable compound will phase separate or precipitate from the LC medium and form a polymer layer on the substrate or electrode, or on the alignment layer provided thereon. Microscopic measurement data (such as SEM and AFM) have confirmed that at least a portion of the polymer formed accumulates at the LC / substrate interface.

[0748] The polymerization can be carried out in one step. It is also possible to first carry out the polymerization in a first step, optionally while applying a voltage, to generate a tilt angle, and subsequently, in a second polymerization step, polymerize or crosslink the compounds that have not reacted in the first step ("final curing") without applying a voltage.

[0749] Suitable and preferred polymerization methods are, for example, thermal polymerization or photopolymerization, preferably photopolymerization, especially UV-induced photopolymerization, which can be achieved by exposing the polymerizable compound to UV radiation.

[0750] The polymerizable compounds of formula M and its sub-formulas do indeed particularly exhibit good UV absorption in the method for preparing a PSA display, and are therefore particularly suitable for the method for preparing a PSA display, which method for preparing a PSA display includes one or more of the following features or any combination thereof:

[0751] - The polymerizable medium is exposed to UV light in a two-step process in the display, the two-step process including a first UV exposure step ("UV1 step") with voltage applied to the electrodes of the display to generate an inclination angle, and a second UV exposure step ("UV2 step") without voltage applied to the electrodes of the display to complete the polymerization of the polymerizable compound.

[0752] - The polymerizable medium is exposed to UV light generated by a UV-LED lamp in the display, preferably at least in the UV2 step, more preferably in both the UV1 and UV2 steps.

[0753] - The polymerizable medium is exposed to UV light generated by energy-saving UV lamps (also known as "green UV lamps") in the display. These lamps are characterized by relatively low intensity in their absorption spectrum of 300 - 380 nm (1 / 100 - 1 / 10 of a conventional UV1 lamp), and are preferably used in the UV2 step, but are also optionally used in the UV1 step when the method requires avoiding high intensity.

[0754] - The polymerizable medium is exposed to UV light generated by a UV lamp having a radiation spectrum shifted to longer wavelengths, preferably ≥340 nm, more preferably 350 to <370 nm, very preferably 355 to 368 nm, to avoid short-term UV light exposure in the PS-VA method.

[0755] Both using lower intensity and shifting the UV to longer wavelengths can protect the organic layer from damage that may be caused by UV light.

[0756] A preferred embodiment of the present invention relates to a method for preparing a PSA display as described above and below, the method including one or more of the following features or any combination thereof:

[0757] - Irradiating the polymerizable LC medium with UV light in a two-step process, the two-step process including a first UV exposure step ("UV1 step") with voltage applied to generate an inclination angle, and a second UV exposure step ("UV2 step") without voltage applied to complete the polymerization of the polymerizable compound.

[0758] - Irradiating the polymerizable LC medium with UV light generated by a UV lamp, the intensity of the UV light being 0.5 mW / cm 2 to 10 mW / cm 2 , and the wavelength range being 300 - 380 nm, preferably in the UV2 step, and optionally also in the UV1 step.

[0759] - irradiating the polymerizable LC medium with UV light having a wavelength of ≥340 nm, preferably ≤420 nm, very preferably in the range of 340 to 380 nm, more preferably in the range of 350 to <370 nm, and most preferably in the range of 355 to 368 nm,

[0760] - irradiating the polymerizable LC medium with UV light while applying a voltage to the electrodes of the display,

[0761] - performing UV light irradiation using a UV-LED lamp.

[0762] For example, this preferred method can be implemented by using the required UV lamp or by using band-pass filters and / or cut-off filters that are substantially transmissive to UV light having one or more corresponding required wavelengths and substantially block light having corresponding unwanted wavelengths. For example, when irradiation with UV light having a wavelength λ in the range of 300 - 400 nm is required, UV exposure can be implemented using a broadband-pass filter that is substantially transmissive to wavelengths of 300 nm < λ < 400 nm. When irradiation with UV light having a wavelength λ greater than 340 nm is required, UV irradiation can be implemented using a cut-off filter that is substantially transmissive to wavelengths λ > 340 nm.

[0763] In a preferred embodiment of the present invention, UV irradiation is performed using a UV-LED lamp.

[0764] In the PSA method, using a UV-LED lamp having only one narrow emission peak provides several advantages. For example, depending on the selection of a suitable polymerizable compound (which exhibits absorption at the emission wavelength of the LED lamp), more efficient transfer of light energy to the polymerizable compound in the LC medium is achieved. This allows for a reduction in UV intensity and / or UV irradiation time, thus enabling a reduced operation time and savings in energy and production costs. Another advantage is that the narrow emission spectrum of the lamp allows for easier selection of a suitable wavelength for photopolymerization.

[0765] Very preferably, the UV light source is a UV-LED lamp that emits wavelengths in the range of 340 to 400 nm, more preferably in the range of 340 to 380 nm. A UV-LED lamp that emits UV light with a wavelength of 365 nm is particularly preferred.

[0766] This preferred method enables the manufacture of displays by using longer UV wavelengths, thereby reducing or even avoiding the harmful and destructive effects of short UV light components.

[0767] The UV radiation energy is generally 6 to 100 J, depending on the conditions of the preparation method.

[0768] The LC medium according to the invention may additionally further comprise one or more further components or additives, which are preferably selected from the substances listed below, including but not limited to: comonomers, chiral dopants, polymerization initiators, inhibitors, stabilizers, surfactants, wetting agents, lubricants, dispersants, water repellents, binders, flow improvers, defoamers, degassing agents, diluents, reactive diluents, auxiliaries, colorants, dyes, pigments and nanoparticles.

[0769] Furthermore, for example, 0 to 15% by weight of a dichroic dye, and in addition nanoparticles, a conductive salt, preferably ammonium ethyl dimethyl dodecyl 4 - hexyloxybenzoate, a complex salt of tetrabutyltetraphenylborate or a crown ether (see, for example, Haller et al., Mol. Cryst. Liq. Cryst. 24 , 249 - 258 (1973)) can be added to the LC medium to improve conductivity, or substances can be added to modify the dielectric anisotropy, viscosity and / or alignment of the nematic phase. Substances of this type are described, for example, in DE - A 22 09 127, 2240 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 28 53 728.

[0770] The individual components of the above - listed preferred embodiments of the LC medium according to the invention are known, or the methods for preparing them can be obtained by a person skilled in the relevant art from the prior art, since they are based on standard methods described in the literature. For example, the corresponding compounds of formula CY are described in EP - A - 0 364 538. The corresponding compounds of formula ZK are described, for example, in DE - A - 26 36 684 and DE - A - 33 21 373.

[0771] The LC medium that can be used according to the invention is prepared in a conventional manner per se, for example by mixing one or more of the above - mentioned compounds with one or more polymerizable compounds as defined above, and optionally with other liquid crystal compounds and / or additives. Usually, the desired amounts of the components used in smaller amounts are dissolved in the components that make up the main components, which is advantageously carried out at an elevated temperature. The solutions of the components can also be mixed in an organic solvent such as acetone, chloroform or methanol, and the solvent is removed again, for example by distillation after thorough mixing. The invention also relates to a method for preparing the LC medium according to the invention.

[0772] It goes without saying for a person skilled in the art that the LC medium according to the invention can also contain, for example, compounds in which H, N, O, Cl, F are replaced by the corresponding isotopes such as deuterium.

[0773] The following examples illustrate the present invention but do not limit the present invention. However, they show preferred mixture concepts to those skilled in the art, as well as the compounds preferably used and their respective concentrations, and their combinations with each other. In addition, the examples illustrate which properties and combinations of properties are obtainable.

[0774] For the present invention and in the following examples, the structures of the liquid-crystal compounds are indicated with the aid of acronyms. Unless otherwise indicated, the conversion into chemical formulae is carried out according to the following Tables A.1 to A.3. All radicals C n H 2n+1 , C m H 2m+1 and C l H 2l+1 or C n H 2n , C m H 2m and C l H 2l is a straight-chain alkyl group or alkylene group having n, m and 1 C atoms, respectively, in each case. Preferably, n, m and 1 are independently 1, 2, 3, 4, 5, 6 or 7. Table A.1 shows the ring element codes of the core structure of the compounds, Table A.2 lists the bridging units, and Table A.3 lists the meanings of the symbols of the left-hand and right-hand end groups of the molecules. The acronyms consist of the code for the ring element with the optional linking group, followed by a first hyphen, and the code for the left-hand end group, and a second hyphen and the code for the right-hand end group.

[0775] Table A.1: Ring Elements

[0776]

[0777]

[0778]

[0779]

[0780] Table A.2: Bridging Units

[0781]

[0782] Table A.3: End Groups

[0783]

[0784]

[0785]

[0786]

[0787] Wherein n and m are each integers, and the three dots "…" are placeholders for other abbreviations from the table.

[0788] Table B shows the schematic structures of the compounds and their corresponding abbreviations.

[0789] Table B

[0790] In Table B, n, m, k, and l are each independently integers, preferably from 1 to 9, more preferably from 1 to 7, k and l can also be 0, preferably from 0 to 4, more preferably 0 or 2, most preferably 2, n is preferably 1, 2, 3, 4, or 5, in the combination "-nO-", n is preferably 1, 2, 3, or 4, very preferably 2 or 4, m is preferably 1, 2, 3, 4, or 5, in the combination "-Om", m is preferably 1, 2, 3, or 4, more preferably 2 or 4. The combination "-nVm" is preferably "2V1". (O)C m H 2m+1 means C m H 2m+1 or OC m H 2m+1 .

[0791]

[0792]

[0793]

[0794]

[0795]

[0796]

[0797]

[0798]

[0799]

[0800]

[0801]

[0802]

[0803]

[0804]

[0805]

[0806]

[0807]

[0808]

[0809]

[0810]

[0811]

[0812]

[0813]

[0814] In a preferred embodiment of the present invention, the LC medium according to the present invention comprises one or more compounds selected from the compounds of Table B.

[0815] Table C

[0816] Table C shows the possible chiral dopants that can be added to the LC medium according to the present invention.

[0817]

[0818]

[0819]

[0820] The LC medium preferably comprises 0 to 10 wt%, especially 0.01 to 5 wt%, particularly preferably 0.1 to 3 wt% of the dopant. The LC medium preferably comprises a dopant selected from one or more compounds of Table C.

[0821] Table D

[0822] Table D shows the possible stabilizers that can be added to the LC medium according to the present invention. Wherein n represents an integer from 1 to 12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, and the terminal methyl groups are not shown.

[0823]

[0824]

[0825]

[0826]

[0827]

[0828]

[0829]

[0830] The LC medium preferably contains 0 to 10 wt%, especially 1 ppm to 5 wt%, and particularly preferably 1 ppm to 1 wt% of a stabilizer. The LC medium preferably contains one or more stabilizers selected from the compounds in Table D.

[0831] Table E

[0832] Table E shows exemplary reactive mesogenic compounds that can be used in the LC medium according to the present invention.

[0833]

[0834]

[0835]

[0836]

[0837]

[0838]

[0839]

[0840]

[0841]

[0842]

[0843]

[0844]

[0845]

[0846]

[0847]

[0848]

[0849]

[0850]

[0851]

[0852] In a preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds, preferably selected from the polymerizable compounds of formulae RM-1 to RM-182. Among 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.

[0853] Table F

[0854] Table F shows the self-aligning compounds for vertical alignment, which can be used together with the polymerizable compounds in the LC medium for SA-VA and SA-FFS displays according to the invention:

[0855]

[0856]

[0857]

[0858]

[0859]

[0860]

[0861]

[0862]

[0863]

[0864]

[0865]

[0866] In a preferred embodiment, the LC media, SA-VA, and SA-FFS displays according to the present invention comprise a combination of one or more SA additives and one or more RMs, said SA additives being selected from the formulas SA-1 to SA-48, preferably from the formulas SA-14 to SA-48, and very preferably from the formulas SA-20 to SA-34 and SA-44. Detailed Description

[0867] Examples

[0868] The following examples illustrate the invention without limiting it. However, they show the skilled person the concept of preferred mixtures and the compounds preferably used, their respective concentrations, and their combinations with each other. Additionally, the examples illustrate the properties and combinations of properties that can be obtained.

[0869] Additionally, the following abbreviations and symbols are used:

[0870] V 0 represents the threshold voltage at 20 °C, capacitive [V],

[0871] n e represents the extraordinary refractive index at 20 °C and 589 nm,

[0872] n o represents the ordinary refractive index at 20 °C and 589 nm,

[0873] Δn represents the optical anisotropy at 20 °C and 589 nm,

[0874] ε ⊥ represents the dielectric constant perpendicular to the director at 20 °C and 1 kHz,

[0875] ε || represents the dielectric constant parallel to the director at 20 °C and 1 kHz,

[0876] Δε represents the dielectric anisotropy at 20 °C and 1 kHz,

[0877] cl.p., T(N,I) represents the clearing point [°C],

[0878] γ 1 represents the rotational viscosity at 20 °C [mPa·s],

[0879] K 1 represents the elastic constant at 20 °C, "splay" deformation [pN],

[0880] K 2 represents the elastic constant at 20 °C, "twist" deformation [pN],

[0881] K 3 represents the elastic constant at 20 °C, "bending" deformation [pN],

[0882] K 平均 represents the average elastic constant at 20 °C [pN], which is defined in this text as K 平均 ≡( 3 / 2 K 1 + K 3 ) / 3 ≈ (K 1 + K 2 + K 3 ) / 3,

[0883] LTS represents the low-temperature stability of the phase, which is measured in a test cell,

[0884] VHR represents the voltage holding ratio

[0885] Unless otherwise explicitly stated, all concentrations in this application are given in weight percentages and refer to the corresponding entire mixture, which includes all solid or liquid crystal components (without solvent).

[0886] Unless otherwise specified, all temperature values indicated in this application, such as the melting point T(C,N), the transition from the smectic phase (S) to the nematic phase (N) T(S,N), and the clearing point T(N,I), are expressed in degrees Celsius (°C). M.p. represents the melting point, cl.p. = clearing point. In addition, C = liquid crystal phase, N = nematic phase, S = smectic phase, and I = isotropic phase. The data between these symbols represent the transition temperatures.

[0887] All physical properties are and have been determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals" Status November 1997, Merck KGaA, Germany, and apply to a temperature of 20 °C, and Δn is measured at 589 nm and Δε is measured at 1 kHz, unless otherwise explicitly stated in each case.

[0888] The term "threshold voltage" used in the present invention relates to the capacitive threshold (V 0 ), which is also referred to as the Freedericks threshold, unless otherwise specified. In the examples, the optical threshold is also given as usual for a relative contrast of 10% (V 10 ).

[0889] Unless otherwise specified, the method of polymerizing polymerizable compounds in a PSA display as described in the context is carried out at a temperature at which the LC medium exhibits a liquid crystal phase, preferably a nematic phase, and most preferably at room temperature.

[0890] Unless otherwise specified, the method of preparing test cells and measuring their electro-optical and other properties is carried out by the method described below or a method similar thereto.

[0891] Unless otherwise stated, the PSVA display or PSVA test cell for photopolymerization and measuring the tilt angle, etc. consists of two planar parallel glass outer plates spaced 3 - 4 μm apart, each of which has an electrode layer on the inner side and a polyimide alignment layer on the top, where the two polyimide layers are rubbed antiparallel to each other, resulting in a homeotropic edge alignment of liquid crystal molecules. The SAVA display or test cell has the same structure, but one or two polyimide layers are omitted therein.

[0892] The polymerizable compound is polymerized in the display or test cell by irradiating with UV light of a defined intensity for a pre-specified time while applying a voltage (usually 10V to 30V alternating current, 1kHz) to the display.

[0893] The tilt angle is measured using the Mueller Matrix Polarimeter “AxoScan” from Axometrics. Here, a low value (i.e., a large deviation from the 90° angle) corresponds to a large tilt.

[0894] Unless otherwise specified, the term “tilt angle” means the angle between the LC director and the substrate, and “LC director” means the preferred orientation direction of the optical axes of the LC molecules in a layer of LC molecules with a uniform orientation, which corresponds to their molecular long axes in the case of calamitic uniaxial positive birefringent LC molecules.

[0895] Comparative Example 1

[0896] The nematic LC mixture C1 is formulated as follows.

[0897]

[0898] Mixture C1 does not contain a compound of formula IA.

[0899] 150 ppm of stabilizer ST-3a-1 is added to mixture C1.

[0900]

[0901] Example 1

[0902] The nematic LC mixture N1 is prepared as follows.

[0903]

[0904] The mixture N1 contains the compound CCOY-3-O1(c5) of formula IA and exhibits a reduced birefringence with little effect on other parameters.

[0905] 150 ppm of the stabilizer ST-3a-1 is added to the mixture N1.

[0906] Example 2

[0907] The nematic LC mixture N2 is prepared as follows.

[0908]

[0909]

[0910] 150 ppm of the stabilizer ST-3b-1 is added to the mixture N2.

[0911]

[0912] Example 3

[0913] The nematic LC mixture N3 is prepared as follows.

[0914]

[0915] 100 ppm of the stabilizer H-1-1-1 is added to the mixture N3.

[0916]

[0917] Example 4

[0918] The nematic LC mixture N4 is prepared as follows.

[0919]

[0920] 50 ppm of the stabilizer H-2-1-1 is added to the mixture N4.

[0921]

[0922] Comparative Example 2

[0923] The nematic LC mixture C2 is prepared as follows.

[0924]

[0925] Mixture C2 does not contain a compound of formula IA.

[0926] Add 150 ppm of stabilizer ST-3a-1 to mixture C2.

[0927] Example 5

[0928] The nematic LC mixture N5 is prepared as follows.

[0929]

[0930]

[0931] Mixture N5 contains the compound CCOY-3-O1(c5) of formula IA and exhibits a reduced birefringence with little effect on other parameters.

[0932] Add 150 ppm of stabilizer ST-3a-1 to mixture N5.

[0933] Example 6

[0934] The nematic LC mixture N6 is prepared as follows.

[0935]

[0936] Add 100 ppm of stabilizer ST-8-1 to mixture N6.

[0937]

[0938] Example 7

[0939] The nematic LC mixture N7 is prepared as follows.

[0940]

[0941] Add 50 ppm of stabilizer ST-9-1 to mixture N6.

[0942]

[0943] Example 8

[0944] The nematic LC mixture N8 is prepared as follows.

[0945]

[0946] Add 50 ppm of stabilizer ST-9-1 to mixture N8.

[0947] Comparative Example 3

[0948] The nematic LC mixture C3 is prepared as follows.

[0949]

[0950]

[0951] Mixture C3 does not contain a compound of formula IA.

[0952] 150 ppm of stabilizer ST-3a-1 is added to mixture C3.

[0953] Example 9

[0954] The nematic LC mixture N9 is prepared as follows.

[0955]

[0956] Mixture N9 contains the compound CCOY-3-O1(c5) of formula IA and exhibits a reduced birefringence with little effect on other parameters.

[0957] 150 ppm of stabilizer ST-3a-1 is added to mixture N9.

[0958] Example 10

[0959] The nematic LC mixture N10 is prepared as follows.

[0960]

[0961]

[0962] 150 ppm of stabilizer ST-3b-1 is added to mixture N10.

[0963] Example 11

[0964] The nematic LC mixture N11 is prepared as follows.

[0965]

[0966] 100 ppm of stabilizer H-1-1-1 is added to mixture N11.

[0967] Example 12

[0968] The nematic LC mixture N12 is prepared as follows.

[0969]

[0970] Add 50 ppm of stabilizer H-2-1-1 to mixture N12.

[0971] Comparative Example 4

[0972] The nematic LC mixture C4 is prepared as follows.

[0973]

[0974] Mixture C4 does not contain a compound of formula IA.

[0975] Add 150 ppm of stabilizer ST-3b-1 to mixture C4.

[0976] Example 13

[0977] The nematic LC mixture N13 is prepared as follows.

[0978]

[0979] Mixture N13 contains the compound CCOY-3-O1(c5) of formula IA and exhibits a reduced birefringence with little effect on other parameters.

[0980] Add 150 ppm of stabilizer ST-3b-1 to mixture N13.

[0981] Example 14

[0982] The nematic LC mixture N14 is prepared as follows.

[0983]

[0984]

[0985] Add 150 ppm of stabilizer ST-8-1 to mixture N14.

[0986] Example 15

[0987] The nematic LC mixture N15 is prepared as follows.

[0988]

[0989] Add 100 ppm of stabilizer ST-9-1 to mixture N15.

[0990] Example 16

[0991] The nematic LC mixture N16 is prepared as follows.

[0992]

[0993] Add 100 ppm of stabilizer H-1-1-1 to mixture N16.

[0994] Example 17

[0995] The nematic LC mixture N17 is prepared as follows.

[0996]

[0997] Add 150 ppm of stabilizer ST-3a-1 to mixture N17.

[0998] Example 18

[0999] The nematic LC mixture N18 is prepared as follows.

[1000]

[1001]

[1002] Add 100 ppm of stabilizer ST-3b-1 to mixture N18.

[1003] Example 19

[1004] The nematic LC mixture N19 is prepared as follows.

[1005]

[1006] Add 100 ppm of stabilizer ST-3b-1 to mixture N19.

[1007] Example 20

[1008] The nematic LC mixture N20 is prepared as follows.

[1009]

[1010]

[1011] Add 100 ppm of stabilizer ST-8-1 to mixture N20.

[1012] Example 21

[1013] The nematic LC mixture N21 is prepared as follows.

[1014]

[1015] Add 100 ppm of stabilizer ST-9-1 to mixture N21.

[1016] Example 22

[1017] The nematic LC mixture N22 is prepared as follows.

[1018]

[1019]

[1020] Add 100 ppm of stabilizer ST-3a-1 to mixture N22.

[1021] Example 23

[1022] The nematic LC mixture N23 is prepared as follows.

[1023]

[1024] Add 100 ppm of stabilizer H-1-1-1 to mixture N23.

[1025] Example 24

[1026] The nematic LC mixture N24 is prepared as follows.

[1027]

[1028]

[1029] Add 100 ppm of stabilizer H-2-1-1 to mixture N24.

[1030] Example 25

[1031] The nematic LC mixture N25 is prepared as follows.

[1032]

[1033] Add 100 ppm of stabilizer ST-3a-1 to mixture N25.

[1034] Example 26

[1035] The nematic LC mixture N26 is prepared as follows.

[1036]

[1037]

[1038] Add 100 ppm of stabilizer ST-3b-1 to mixture N26.

[1039] Example 27

[1040] The nematic LC mixture N27 is formulated as follows.

[1041]

[1042] Add 100 ppm of stabilizer ST-3a-1 to mixture N27.

[1043] Example 28

[1044] The nematic LC mixture N28 is formulated as follows.

[1045]

[1046]

[1047] Add 100 ppm of stabilizer ST-9-1 to mixture N28.

[1048] Example 29

[1049] The nematic LC mixture N29 is formulated as follows.

[1050]

[1051] Add 100 ppm of stabilizer ST-3a-1 to mixture N29.

[1052] Example 30

[1053] The nematic LC mixture N30 is formulated as follows.

[1054]

[1055]

[1056] Add 100 ppm of stabilizer ST-3b-1 to mixture N30.

[1057] Example 31

[1058] The nematic LC mixture N31 is formulated as follows.

[1059]

[1060] Add 100 ppm of stabilizer ST-8-1 to mixture N31.

[1061] Example 32

[1062] The nematic LC mixture N32 was formulated as follows.

[1063]

[1064]

[1065] 100 ppm of the stabilizer ST-9-1 was added to the mixture N32.

[1066] Example 33

[1067] The polymerizable mixture was prepared as follows: by adding 0.3% of the polymerizable compound RM-171 and 100 ppm of the stabilizer ST-3a-1 to the mixture N1 of Example 1.

[1068]

[1069] Example 34

[1070] The polymerizable mixture was prepared as follows: by adding 0.2% of the polymerizable compound RM-171 and 100 ppm of the stabilizer ST-3a-1 to the mixture N2 of Example 2.

[1071] Example 35

[1072] The polymerizable mixture was prepared as follows: by adding 0.25% of the polymerizable compound RM-1 and 150 ppm of the stabilizer ST-8-1 to the mixture N1 of Example 1.

[1073]

[1074] Example 36

[1075] The polymerizable mixture was prepared as follows: by adding 0.3% of the polymerizable compound RM-35 and 50 ppm of the stabilizer H-1-1-1 to the mixture N1 of Example 1.

[1076]

[1077] Example 37

[1078] The polymerizable mixture was prepared as follows: by adding 0.3% of the polymerizable compound RM-120 and 150 ppm of the stabilizer ST-9-1 to the mixture N2 of Example 2.

[1079]

[1080] Example 38

[1081] A polymerizable mixture is prepared as follows: 0.3% of polymerizable compound RM-142 and 50 ppm of stabilizer H-2-1-1 are added to mixture N3 of Example 3.

[1082]

[1083] Example 39

[1084] A polymerizable mixture is prepared as follows: 0.3% of polymerizable compound RM-143 and 100 ppm of stabilizer ST-8-1 are added to mixture N4 of Example 4.

[1085]

[1086] Example 40

[1087] A polymerizable mixture is prepared as follows: 0.3% of polymerizable compound RM-172 and 100 ppm of stabilizer H-2-1-1 are added to mixture N6 of Example 6.

[1088]

[1089] Example 41

[1090] A polymerizable mixture is prepared as follows: 0.3% of polymerizable compound RM-159 and 50 ppm of stabilizer H-1-1-1 are added to mixture N5 of Example 5.

[1091]

[1092] Example 42

[1093] A polymerizable mixture is prepared as follows: 0.3% of polymerizable compound RM-145 is added to mixture N1 of Example 1.

[1094]

[1095] Example 43

[1096] A polymerizable mixture is prepared as follows: 0.3% of polymerizable compound RM-156 and 150 ppm of stabilizer ST-3a-1 are added to mixture N8 of Example 8.

[1097]

[1098] Example 44

[1099] Prepare a polymerizable mixture as follows: by adding 0.35% of polymerizable compound RM-162 and 50 ppm of stabilizer H-2-1-1 to mixture N9 of Example 9.

[1100]

[1101] Example 45

[1102] Prepare a polymerizable mixture as follows: by adding 0.4% of polymerizable compound RM-58 and 150 ppm of stabilizer ST-3a-1 to mixture N11 of Example 11.

[1103]

[1104] Example 46

[1105] Prepare a polymerizable mixture as follows: by adding 0.25% of polymerizable compound RM-160 and 100 ppm of stabilizer ST-8-1 to mixture N10 of Example 10.

[1106]

[1107] Example 47

[1108] Prepare a polymerizable mixture as follows: by adding 0.3% of polymerizable compound RM-163 and 150 ppm of stabilizer ST-9-1 to mixture N12 of Example 12.

[1109]

[1110] Example 48

[1111] Prepare a polymerizable mixture as follows: by adding 0.35% of polymerizable compound RM-64 and 150 ppm of stabilizer ST-3a-1 to mixture N13 of Example 13.

[1112]

[1113] Example 49

[1114] Prepare a polymerizable mixture as follows: by adding 0.25% of polymerizable compound RM-169 and 150 ppm of stabilizer ST-3b-1 to mixture N15 of Example 15.

[1115]

[1116] Example 50

[1117] The polymerizable mixture is prepared as follows: By adding 0.25% of the polymerizable compound RM-157 and 100 ppm of the stabilizer H-1-1-1 to the mixture N14 of Example 14.

[1118]

[1119] Example 51

[1120] The polymerizable mixture is prepared as follows: By adding 0.3% of the polymerizable compound RM-171, 0.1% of the polymerizable compound RM-1 and 100 ppm of the stabilizer ST-3a-1 to the mixture N16 of Example 16.

[1121] Example 52

[1122] The polymerizable mixture is prepared as follows: By adding 0.25% of the polymerizable compound RM-35, 0.2% of the polymerizable compound RM-1 and 150 ppm of the stabilizer ST-8-1 to the mixture N17 of Example 17.

[1123] Example 53

[1124] The polymerizable mixture is prepared as follows: By adding 0.35% of the polymerizable compound RM-171, 0.1% of the polymerizable compound RM-64 and 50 ppm of the stabilizer H-2-1-1 to the mixture N22 of Example 22.

[1125] Example 54

[1126] The polymerizable mixture is prepared as follows: By adding 0.1% of the polymerizable compound RM-120, 0.3% of the polymerizable compound RM-1 and 100 ppm of the stabilizer H-1-1-1 to the mixture N23 of Example 23.

[1127] Example 55

[1128] The polymerizable mixture is prepared as follows: By adding 0.1% of the polymerizable compound RM-143, 0.25% of the polymerizable compound RM-1 and 150 ppm of the stabilizer ST-3b-1 to the mixture N26 of Example 26.

[1129] Example 56

[1130] The polymerizable mixture was prepared as follows: 0.25% of polymerizable compound RM-171, 0.2% of polymerizable compound RM-120, and 150 ppm of stabilizer ST-9-1 were added to mixture N31 of Example 31.

[1131] Example 56

[1132] The polymerizable mixture was prepared as follows: 0.3% of polymerizable compound RM-1, 0.2% of polymerizable compound RM-145, 0.05% of polymerizable compound RM-163, and 150 ppm of stabilizer ST-3a-1 were added to mixture N1 of Example 1.

[1133] Example 57

[1134] The polymerizable mixture was prepared as follows: 0.3% of polymerizable compound RM-171, 0.2% of polymerizable compound RM-145, 0.05% of polymerizable compound RM-163, and 150 ppm of stabilizer ST-3b-1 were added to mixture N12 of Example 12.

[1135] Example 58

[1136] The polymerizable mixture was prepared as follows: 0.3% of polymerizable compound RM-19, 0.2% of polymerizable compound RM-145, 0.05% of polymerizable compound RM-163, and 150 ppm of stabilizer ST-8-1 were added to mixture N21 of Example 21.

[1137]

[1138] Example 59

[1139] The polymerizable mixture was prepared as follows: 0.3% of polymerizable compound RM-171, 0.2% of polymerizable compound RM-145, and 150 ppm of stabilizer ST-3a-1 were added to mixture N18 of Example 18.

[1140] Example 60

[1141] The polymerizable mixture was prepared as follows: 0.3% of polymerizable compound RM-1, 0.2% of polymerizable compound RM-171, 0.05% of polymerizable compound RM-163, and 150 ppm of stabilizer ST-3a-1 were added to mixture N27 of Example 31.

[1142] Example 61

[1143] A polymerizable mixture is prepared as follows: By adding 0.3% of polymerizable compound RM-1, 0.2% of polymerizable compound RM-35, 0.05% of polymerizable compound RM-163, and 150 ppm of stabilizer ST-3b-1 to mixture N32 of Example 32.

[1144] Example 62

[1145] A polymerizable mixture is prepared as follows: By adding 0.3% of polymerizable compound RM-171, 0.2% of polymerizable compound RM-120, and 150 ppm of stabilizer ST-3a-1 to mixture N30 of Example 30.

[1146] Example 63

[1147] A polymerizable mixture is prepared as follows: By adding 0.3% of polymerizable compound RM-35, 0.2% of polymerizable compound RM-143, 0.05% of polymerizable compound RM-163, and 150 ppm of stabilizer ST-3a-1 to mixture N19 of Example 19.

[1148] Example 64

[1149] A polymerizable mixture is prepared as follows: By adding 0.3% of polymerizable compound RM-1, 0.2% of polymerizable compound RM-171, 0.05% of polymerizable compound RM-163, and 150 ppm of stabilizer ST-3a-1 to mixture N24 of Example 24.

[1150] Example 65

[1151] A polymerizable mixture is prepared as follows: By adding 0.3% of polymerizable compound RM-171, 0.2% of polymerizable compound RM-64, and 150 ppm of stabilizer ST-3b-1 to mixture N29 of Example 29.

[1152] Example 66

[1153] A polymerizable mixture is prepared as follows: By adding 0.3% of polymerizable compound RM-76 and 150 ppm of stabilizer ST-3a-1 to mixture N1 of Example 1.

[1154]

[1155] Example 67

[1156] The polymerizable mixture is prepared as follows: By adding 0.3% of the polymerizable compound RM-76 and 150 ppm of the stabilizer ST-3a-1 to the mixture N3 of Example 3.

[1157] Example 68

[1158] The polymerizable mixture is prepared as follows: By adding 0.3% of the polymerizable compound RM-76 and 150 ppm of the stabilizer ST-3a-1 to the mixture N11 of Example 11.

Claims

1. LC medium having negative dielectric anisotropy and comprising one or more compounds of formula IA where the individual radicals have the following meanings, identically or differently on each occurrence and independently of one another: R 1A is a straight-chain, branched or cyclic alkyl radical having 1 to 15 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CR- 0 =CR 00 -、-C≡C-、 substituted, and wherein one or more H atoms are each optionally replaced by F or Cl, preferably alkyl or alkoxy with 1 to 6 C atoms, R 2A is alkyl or alkoxy having 1 to 12 C atoms, wherein one or more non-adjacent CH2 groups are replaced by cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl, L 1A , L 2A is F, Cl, CF3 or CHF2, Y is H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, particularly preferably H, n is 0 or 1.

2. LC medium according to claim 1, characterized in that In the compound of formula IA, R 2A Selected from the following groups:

3. LC medium according to claim 1 or 2, characterized in that The compound of formula IA is selected from the following sub-formulae:

4. LC medium according to any one of claims 1 to 3, characterized in that It also comprises one or more compounds selected from the group consisting of compounds of formula IIA, IIB, IIC and IID where the individual radicals have the following meanings, identically or differently on each occurrence and independently of one another: R 21 , R 22 is H, an alkyl, alkoxy or alkenyl radical having up to 15 C atoms, which is unsubstituted or monosubstituted by F, Cl, CN or CF3, and wherein in addition, one or more CH2 groups in these radicals may be replaced by -O-, -S-, -C≡C-, -CF2O-, -OCF2-, -OC-O-, -O-CO ... Substitution, where R in Formula IID 21 Unlike cyclic alkyl or alkoxy groups, L 1 To L 4 is F, Cl, CF3 or CHF2, Y is H, F, Cl, CF3, CHF2 or CH3, Z 1 , Z 2 For single bonds, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CH=CHCH2O, p is 0, 1, or 2, and q is 0 or 1.

5. LC medium according to any one of claims 1 to 4, characterized in that It additionally comprises one or more compounds of formula III in R 31 and R 32 each independently of one another represents H, alkyl, alkoxy or alkenyl having up to 15 C atoms, which is unsubstituted, monosubstituted by F, Cl, CN or CF3 or at least monosubstituted by halogen, wherein in addition one or more CH2 groups in these radicals may be replaced by -O-, -S-, -S-, -S- or -S- in such a way that the O atoms are not directly connected to one another. -C≡C-, -CF2O-, -OCF2-, -OC-O- or -O-CO-, Y 1 ,Y 2 is H, F, Cl, CF3, CHF2, CH3 or OCH3, preferably H, CH3 or OCH3, very preferably H, A 3 Each occurrence represents independently of each other a) 1,4-cyclohexenyl or 1,4-cyclohexylene, in which one or two non-adjacent CH2 groups may be replaced by -O- or -S-, b) 1,4-phenylene, in which one or both CH groups may be replaced by N, or c) a radical selected from the group consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octane-2,6-diyl, 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, wherein the groups a), b) and c) may be substituted singly or polysubstituted by halogen atoms, n represents 0, 1 or 2, preferably 0 or 1, Z 1 Each occurrence independently represents -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, and L 11 and L 12 each independently of one another represents F, Cl, CF3 or CHF2, preferably H or F, most preferably F, and W represents O or S.

6. LC medium according to one or more of claims 1 to 5, characterized in that It additionally comprises one or more compounds selected from the following formulae: wherein alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1 to 6 C atoms, and (O) represents an oxygen atom or a single bond.

7. LC medium according to one or more of claims 1 to 6, characterized in that It additionally comprises one or more compounds of the formulae IV-1 to IV-4: in Alkyl and alkyl' independently represent an alkyl radical having 1 to 7 C atoms, Alkenyl represents an alkenyl group having 2 to 5 C atoms, alkenyl ’ represents an alkenyl group having 2 to 5 C atoms, and Alkoxy represents an alkoxy group having 1 to 5 C atoms.

8. LC medium according to one or more of claims 1 to 7, characterized in that It additionally comprises one or more additives selected from polymerizable compounds, stabilizers, chiral dopants, polymerization initiators and self-aligning additives.

9. Process for the preparation of an LC medium according to one or more of claims 1 to 8, comprising the following steps: One or more compounds of the formula IA as defined in any one of claims 1 to 3 are mixed with one or more further LC compounds and optionally with one or more additives.

10. LC display comprising an LC medium as defined in one or more of claims 1 to 8.

11. The LC display according to claim 10, characterized in that It is VA, IPS, FFS, UB-FFS or UV 2 A-mode LC display.

12. Use of an LC medium according to one or more of claims 1 to 8 or an LC display according to claim 10 or 11 for energy-saving LC displays.

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