Liquid crystal medium

Abstract

The present invention relates to a liquid crystal (LC) medium comprising a polymerizable compound, its use for optical, electro-optical and electronic purposes, in particular in LC displays, especially in PSA (polymer stabilized alignment) or SA (self-alignment) type LC displays, an LC display in PSA or SA mode comprising such an LC medium, and a method for manufacturing such an LC display.

Description

Field of the Invention

[0001] The present invention relates to a liquid crystal (LC) medium comprising polymerizable compounds, for use in optical, electro-optical and electronic purposes, in particular for use in LC displays, especially in PSA (polymer stabilized alignment) or SA (self-alignment) type LC displays, an LC display in PSA or SA mode comprising such an LC medium, and a method of manufacturing such an LC display. Background Art

[0002] The spread of 8K and gaming monitors has led to an increased demand for LC display (LCD) panels with higher refresh rates, and thus also an increased demand for LC media with faster response times. Many of these LCD panels use polymer stabilized (PS) or polymer stabilized alignment (PSA) modes, such as PS-VA (vertically aligned), PS-IPS (in-plane switching) or PS-FFS (fringe field switching) modes or derivatives thereof, or self-alignment (SA) modes such as SA-VA, which are polymer stabilized.

[0003] In the PS or PSA mode, a small amount, typically 0.1 - 1%, of one or more polymerizable mesogenic compounds (also called RM (reactive mesogen)) is added to the LC medium. After filling the LC medium into the display, the RM is then polymerized in situ by UV light polymerization while applying a voltage to the electrodes of the display. Thereby, a small tilt angle is generated in the LC molecules of the LC medium, which is stabilized by the polymerized RM. The UV polymerization method (also called "PSA method") is typically carried out in two steps: a first UV exposure step ("UV1 step"), applying a voltage to generate the tilt angle, and a second UV exposure step ("UV2 step"), without applying a voltage, to complete the RM polymerization.

[0004] In the SA-VA mode, the alignment layer is omitted in the display. Instead, a small amount, typically 0.1 - 2.5%, of a self-alignment (SA) additive is added to the LC medium, which in situ initiates the desired alignment, such as vertical or planar alignment, by a self-assembly mechanism. The SA additive typically contains an organic mesogenic core group and one or more polar anchoring groups, such as hydroxyl, carboxyl, amino or thiol groups, which are capable of interacting with the substrate surface, causing the additive to align on the substrate surface and inducing the desired alignment in the LC molecules. The SA additive may also contain one or more polymerizable groups, which can be polymerized under conditions similar to those used for the RM in the PSA method. In addition to the SA additive, the LC medium also contains one or more RM.

[0005] One way to reduce the response time of the LC medium to the PSA mode is, for example, by using a compound having an alkenyl group as a component of the LC host mixture. However, this may lead to a reduction in the reliability of the mixture when exposed to the UV light required for polymerizing the RM additive, which is thought to be caused by the reaction of the alkenyl compound with the polyimide of the alignment layer, and is particularly problematic when using shorter UV wavelengths of less than 320 nm. Therefore, there is a trend to use longer UV wavelengths for the PSA method.

[0006] Another way to reduce the response time in the LC medium for the PSA mode is by adjusting the cell gap towards a higher / lower cell gap.

[0007] It is also proposed to use UV-LED lamps in the PSA method, as they exhibit less power consumption, longer lifetime and more efficient light energy transfer to the LC medium due to their narrower emission peaks, which enables reducing the UV intensity and / or UV irradiation time. This can shorten the cycle time and save energy and production costs. Currently available UV lamps have higher wavelength emissions, for example at 365 nm.

[0008] Therefore, there is a need for polymerizable LC media for PSA or SA displays that can have a high resistivity, while having a large operating temperature range, short response time, even at low temperatures, and low threshold voltage, low tilt angle, high tilt stability, multiple gray levels, high contrast and wide viewing angle, high reliability and high VHR value after UV exposure, and in the case of polymerizable compounds, low melting point and high solubility in the LC host mixture, and enabling polymerization even at longer UV wavelengths. In displays for mobile applications, it is particularly desirable to have available LC media that exhibit low threshold voltage and high birefringence. Summary of the Invention

[0009] The present invention is based on the following object: to provide novel suitable materials, in particular RM and LC media containing RM, for use in PSA or SA displays that do not have the above disadvantages or have the above disadvantages to a reduced extent.

[0010] In particular, the present invention is based on the following objectives: an LC medium containing RM for PSA or SA displays, which can have a very high specific resistance value, a high VHR value, high reliability, a low threshold voltage, a short response time, a high birefringence, also show good UV absorption at longer UV wavelengths, preferably 340 - 380 nm, can polymerize RM quickly and completely, can produce a low tilt angle, preferably as quickly as possible, can have high tilt stability, even after a longer time and / or after UV exposure, reduce or prevent "image sticking" and "ODF non-uniformity (mura)" in the display, and show high solubility in the LC medium when RM polymerizes as quickly and completely as possible, and the LC medium is generally used as the host mixture of PSA or SA displays.

[0011] Another object of the present invention is to provide an LC medium for PSA displays, in which RM shows both a fast polymerization rate and good reliability parameters, such as high VHR or tilt stability.

[0012] Another object of the present invention is to provide a novel RM-containing LC medium, especially for optical, electro-optical and electronic applications, as well as suitable methods and intermediates for preparing the same.

[0013] It has been found that one or more of these objects can be achieved by providing the LC medium as described and claimed herein.

[0014] The present invention also relates to an LC medium comprising

[0015] - polymerizable component A), comprising, preferably consisting of: one or more polymerizable compounds, and

[0016] - liquid crystal component B), also referred to hereinafter as "LC host mixture", comprising, preferably consisting of: one or more mesogenic or liquid crystal compounds,

[0017] wherein component B) comprises one or more compounds of formula IA, one or more compounds of formula IB and one or more compounds of formula IC

[0018]

[0019]

[0020] where each group is the same or different each time it appears, and each is independently of the others as follows:

[0021] R 1 ,R 2 is a straight-chain, branched-chain or cyclic alkyl group having 1 - 25 C atoms, where one or more non-adjacent CH 2- The group is optionally substituted by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CR 0 =CR 00 -, -C≡C-, in such a way that the O- and / or S-atoms are not directly connected to each other, and wherein one or more H atoms are each optionally substituted by F or Cl, preferably an alkyl or alkoxy group having 1 - 6 C atoms,

[0022] R 0 , R 00 is H or an alkyl group having 1 to 12 C atoms,

[0023] L 1 , L 2 is F or Cl, preferably F,

[0024] alkyl is an alkyl group having 1 to 7 carbon atoms, preferably having 2 to 5 C atoms, particularly preferably n-propyl,

[0025] alkenyl is an alkenyl group having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably vinyl or 1-propenyl,

[0026] wherein the proportion of the compound of formula IA in component B) of the LC medium is > 5% by weight, preferably > 8% by weight.

[0027] The liquid crystal component B) of the LC medium according to the invention is also referred to hereinafter as "LC host mixture", and preferably contains only LC compounds selected from non-polymerizable low molecular weight compounds, such as compounds of formula IA, IB or IC, and optionally contains additives such as polymerization initiators, inhibitors, etc.

[0028] The invention also relates to an LC medium or an LC display as described above and below, wherein the polymerizable compound of component A) is polymerized.

[0029] The invention also relates to a method for preparing an LC medium as described above and below, the method comprising the steps of: mixing one or more compounds of formula IA, IB and IC or an LC host mixture or LC component B) as described above and below with one or more polymerizable compounds and optionally other LC compounds and / or additives.

[0030] The invention also relates to the use of the LC medium in an LC display, particularly in an LC display in PSA or SA mode.

[0031] The invention also relates to the use of the LC medium according to the invention in a PSA display, in particular in a PSA display comprising an LC medium, for generating a tilt angle in the LC medium by in-situ polymerization of the polymerizable compound of component B in the PSA display, preferably in an electric or magnetic field.

[0032] The invention also relates to an LC display comprising one or more compounds of formula I or an LC medium according to the invention, which is preferably a PSA display, very preferably a PS-VA, PS-IPS or PS-UB-FFS display.

[0033] The invention further relates to an LC display comprising an LC medium as described above, wherein the polymerizable compound is present in polymerized form, which is preferably a PSA or SA display, very preferably a PS-VA, PS-IPS, PS-FFS or SA-VA display.

[0034] The invention further relates to a PSA type LC display comprising two substrates, at least one of which is transparent to light, an electrode provided on each substrate, or two electrodes provided on only one substrate, and a layer of the LC medium as described above located between the substrates, wherein the polymerizable compound is polymerized by UV light polymerization between the substrates of the display.

[0035] The invention also relates to a method of manufacturing an LC display as described above, comprising the steps of filling or otherwise providing the LC medium as described above between the substrates of the display, and polymerizing the polymerizable compound, preferably while applying a voltage to the electrodes of the display.

[0036] The invention further relates to a method of manufacturing an LC display as described above, wherein the irradiation of the polymerizable compound is carried out using a UV-LED lamp.

[0037] When used in a PSA display, the LC medium according to the invention exhibits one or more of the following advantageous properties:

[0038] - High transmittance,

[0039] - High contrast,

[0040] - Reduced image sticking,

[0041] - Reduced ODF non-uniformity,

[0042] - Reduced rotational viscosity,

[0043] - High reliability and high VHR value after UV exposure and / or heat treatment,

[0044] - Fast response time,

[0045] - Strong tilt generation within a certain process window

[0046] - Fast polymerization, resulting in the lowest residual amount of RM after UV treatment

[0047] - Good tilt stability.

[0048] As described below, the alkenyl groups in the compounds of formula IA, IB, II or other components of the LC medium are not considered to be within the meaning of the term "polymerizable group" as used herein. The polymerization conditions of the polymerizable compounds of the LC medium are preferably selected 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.

[0049] Unless otherwise specified, the polymerizable compounds and the compounds of formula II are preferably selected from achiral compounds.

[0050] As used herein, the expression "UV light having a wavelength of..." followed by a given range of wavelengths (in nm), or a given lower or upper wavelength limit (in nm), means that the UV emission spectrum of the corresponding irradiation source has an emission peak, which is preferably the highest peak in the corresponding spectrum within the given wavelength range or above the given lower wavelength limit or below the given upper wavelength limit, and / or the UV absorption spectrum of the corresponding chemical compound has a long-wavelength tail or a short-wavelength tail extending into the given wavelength range or above the given lower wavelength limit or below the given upper wavelength limit.

[0051] As used herein, the term "substantially transmits" means that the filter transmits a substantial portion of the incident light of the desired wavelength, preferably at least 50% intensity. As used herein, the term "substantially blocks" means that the filter does not transmit a substantial portion of the incident light of the undesired wavelength, preferably at least 50% intensity. As used herein, the term "desired (undesired) wavelength" means, for example, for a bandpass filter, a wavelength within (outside) a given range λ, and for a cut-off filter, a wavelength above (below) a given λ value.

[0052] As used herein, the terms "active layer" and "switchable layer" refer to layers in an electro-optical display, such as an LC display, which contain 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 transmittance of the layer for polarized or non-polarized light.

[0053] As used herein, the terms "tilt" and "tilt angle" shall be understood to denote the tilted alignment of the LC molecules of the LC medium relative to the cell surface in an LC display (preferably a PSA display herein), and shall be understood to include "pretilt" and "pretilt angle". The tilt angle herein represents the average angle (<90°) between the longitudinal molecular axis (LC director) of the LC molecules and the surface of the planar outer plate forming the LC cell. A low absolute value tilt angle herein (i.e., a large deviation from the 90° angle) corresponds to a large tilt. Suitable methods for measuring the tilt angle are given in the examples. Unless otherwise stated, the tilt angle values disclosed in the context are related to such measuring methods.

[0054] As used herein, the terms "reactive mesogen" and "RM" shall be understood to denote a compound containing a mesogenic or liquid crystal backbone and one or more polymerizable functional groups attached thereto, and said functional groups are also referred to as "polymerizable groups" or "P".

[0055] Unless otherwise stated, the term "polymerizable compound" as used herein shall be understood to denote a polymerizable monomer compound.

[0056] The SA-VA display of the present invention will be in a polymer-stabilized mode since it contains an LC medium containing RMs of Formulas I and II or is manufactured by using an LC medium containing RMs of Formulas I and II. Thus, as used herein, even if not explicitly mentioned, the term "SA-VA display" shall be understood to refer to a polymer-stabilized SA-VA display when referring to the display of the present invention.

[0057] As used herein, the term "low molecular weight compound" shall be understood to denote monomers and / or compounds not prepared by a polymerization reaction, as opposed to "polymeric compounds" or "polymers".

[0058] As used herein, the term "non-polymerizable compound" will be understood to denote a compound that does not contain functional groups suitable for polymerization under the conditions normally applied for the polymerization of RMs.

[0059] As used herein, the term "mesogenic group" is known to those skilled in the art and is described in the literature, and it refers to a group that substantially contributes to the formation of a liquid crystal (LC) phase in low molecular weight or polymeric substances due to the anisotropy of its attractive and repulsive interactions. A compound containing a mesogenic group (mesogenic compound) does not necessarily have an LC phase per se. A mesogenic compound can exhibit LC phase behavior only after mixing with other compounds and / or after polymerization. Typical mesogenic groups are, for example, rigid rod-like or disc-like units. Terms and definitions related to mesogenic or LC compounds are given in Pure Appl. Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340 - 6368.

[0060] As used herein, the term "spacer group" (also referred to hereinafter as "Sp") is known to those skilled in the art in the prior 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" refers to a flexible group, for example, an alkylene group, which is connected to a mesogenic group or a polymerizable group in a polymerizable mesogenic compound. In the context, represents a trans - 1,4 - cyclohexylene ring, and represents a 1,4 - phenylene ring.

[0061] In the group the single bond between the two ring atoms can be connected to any free position of the benzene ring.

[0062] If in the formula shown in the context the group R 1-12 , R Q , R or L represents an alkyl and / or alkoxy group, it can be straight-chain or branched-chain. It is preferably straight-chain, having 2, 3, 4, 5, 6 or 7 C atoms and correspondingly, 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.

[0063] If in the formula shown in the context the group R 1-12 , R Q , R or L represents one or more CH 2An alkyl group in which the group is replaced by S, which may be straight-chain or branched-chain. It is preferably straight-chain, having 1, 2, 3, 4, 5, 6 or 7 C atoms and correspondingly preferably represents methylthio, ethylthio, propylthio, butylthio, pentylthio, hexylthio or heptylthio.

[0064] The oxaalkyl group 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.

[0065] If in the formula shown by the context the group R 1-12 , R or L represents an alkoxy group or an oxaalkyl group, it may also contain one or more additional oxygen atoms, provided that the oxygen atoms are not directly connected to each other.

[0066] In another preferred embodiment, one or more of R 1-12 , R Q , R or L are selected from -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 very preferably selected from the following groups: -OCH 2 OCH 3 , -O(CH 2 ) 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.

[0067] If, in the formulae as shown in the context, the group R 1-12 , R Q , R or L represents an alkyl group in which one of the CH 2 groups has been replaced by -CH=CH-, then it can be straight-chain or branched. It is preferably straight-chain and has 2 - 10 C atoms. Correspondingly, it represents, in particular, 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, in the formulae as shown in the context, the group R 1-12 , R Q , R or L represents an alkyl or alkenyl group mono-substituted at least by a halogen, the group is preferably straight-chain, and the halogen is preferably F or Cl. In the case of multi-substitution, the halogen is preferably F. The resulting group also includes perfluorinated groups. In the case of mono-substitution, the fluorine or chlorine substituent can be at any desired position, but is preferably at the ω-position.

[0069] The halogen is preferably F or Cl, very preferably F.

[0070] The group -CR 0 =CR 00 - is preferably -CH=CH-.

[0071] -CO-, -C(=O)- and -C(O)- represent a carbonyl group, i.e.

[0072] 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 to 25 C atoms, wherein one or more H atoms may optionally be replaced by F or Cl, an optionally substituted silyl group having 1 to 20 Si atoms, or an optionally substituted aryl group having 6 to 25, preferably 6 to 15 C atoms,

[0073] wherein R x represents H, F, Cl, CN, or a straight-chain, branched-chain or cyclic alkyl group having 1 to 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

[0074] Y 1 represents a halogen.

[0075] 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.

[0076] Preferably

[0077] wherein L has one of the meanings described above.

[0078] 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 a group suitable for polymer-analogous reactions, such as addition or condensation on the polymer backbone. Particularly preferred are groups for chain polymerization, especially those containing C═C double bonds or -C≡C- triple bonds, and groups suitable for ring-opening polymerization, such as oxetane or epoxy groups.

[0079] Preferred groups P are selected from the following groups

[0080] 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 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF 3 , phenyl or an alkyl group having 1 - 5 C atoms, especially H, F, Cl or CH 3 , W 2 and W3 Each independently 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 represents Cl, an oxaalkyl group or an oxacarbonylalkyl group having 1 to 5 C atoms, W 7 and W 8 Each independently 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 different from P-Sp- as defined above, k 1 ,k 2 and k 3 Each independently represents 0 or 1, k 3 preferably represents 1, and k 4 represents an integer from 1 to 10.

[0081] Very preferably, the group P is selected from the following groups:

[0082] 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 ) 2 N-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 - 5 C atoms, especially H, F, Cl or CH 3 , W 2 and W 3 each independently of one another represent H or an alkyl group having 1 - 5 C atoms, especially H, methyl, ethyl or n - propyl, W 4 , W 5 and W 6 each independently of one another represent Cl, an oxaalkyl group or an oxacarbonylalkyl group having 1 - 5 C atoms, W 7 and W 8 each independently of one another represent H, Cl or an alkyl group having 1 - 5 C atoms, Phe represents 1,4 - phenylene, k 1 , k 2 and k 3 each independently of one another represent 0 or 1, k 3 preferably represents 1, and k 4 represents an integer from 1 - 10.

[0083] A very particularly preferred group P is selected from the groups 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 CH 2 =CH - O -, (CH 2 =CH) 2 CH - O - CO -, (CH 2 =CH) 2 CH - O -, and

[0084] A further preferably polymerizable group P is selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy groups, most preferably acrylate and methacrylate groups.

[0085] It is very preferred that all polymerizable groups in the polymerizable compound have the same meaning.

[0086] If the spacer group Sp is different from a single bond, it is preferably of the formula Sp"-X" such that each group P-Sp- conforms to the formula P-Sp"-X"-, where

[0087] Sp" represents a linear or branched alkylene having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN and in which, furthermore, one or more non-adjacent CH 2 groups may 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,

[0088] 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,

[0089] R 0 and R00 each independently represents H or an alkyl group having 1 to 20 C atoms, and

[0090] Y 2 and Y 3 each independently represents H, F, Cl or CN.

[0091] X" is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -, -NR 0 -, -CO-, -NR 0 -, -CO-NR 00 - or a single bond.

[0092] 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 as described above.

[0093] 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 as described above.

[0094] 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, vinylidene, propenylene and butenylene.

[0095] In a preferred embodiment of the present invention, the compounds of formula I and its sub-formulae contain a spacer group Sp 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 group).

[0096] Preferred compounds of formula I according to this preferred embodiment are those in which s is 2, i.e., containing the group Sp(P) 2 Compounds. Very preferred compounds of formula I according to this preferred embodiment contain a group selected from the following formulae:

[0097] -X-alkyl-CHPP S1

[0098] -X-alkyl-CH((CH 2 ) aa P)((CH 2 ) bb P) S2

[0099] -X-N((CH 2 ) aa P)((CH 2 ) bb P) S3

[0100] -X-alkyl-CHP-CH 2 -CH 2 P S4

[0101] -X-alkyl-C(CH 2 P)(CH 2 P)-C aa H 2aa+1 S5

[0102] -X-alkyl-CHP-CH 2 P S6

[0103] -X-alkyl-CPP-C aa H2aa+1 S7

[0104] -X-alkyl-CHPCHP-C aa H 2aa+1 S8

[0105] wherein P is as defined in formula I,

[0106] alkyl represents a single bond or a straight-chain or branched alkylene having 1 to 12 C atoms, which is unsubstituted or mono- or polysubstituted by F, Cl or CN and in which one or more non-adjacent CH 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-, where R 0 has the meaning as described above,

[0107] aa and bb each independently of one another represent 0, 1, 2, 3, 4, 5 or 6,

[0108] X has one of the meanings as described for X", and is preferably O, CO, SO 2 , O-CO-, CO-O or a single bond.

[0109] Preferred spacer group Sp(P) 2 is selected from formulae S1, S2 and S3.

[0110] Very preferred spacer group Sp(P) 2 is selected from the following sub-formulae:

[0111] -CHPP S1a

[0112] -O-CHPP S1b

[0113] -CH 2 -CHPP S1c

[0114] -OCH 2 -CHPP S1d

[0115] -CH(CH 2 -P)(CH 2 -P) S2a

[0116] -OCH(CH 2 -P)(CH 2 -P) S2b

[0117] -CH 2-CH(CH 2 -P)(CH 2 -P) S2c

[0118] -OCH 2 -CH(CH 2 -P)(CH 2 -P) S2d

[0119] -CO-NH((CH 2 ) 2 P)((CH 2 ) 2 P) S3a

[0120] P is preferably selected from ethenyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy groups, very preferably acrylate and methacrylate groups, and most preferably methacrylate groups.

[0121] It is further preferred that all polymerizable groups P present in the same compound have the same meaning, and very preferably represent acrylate or methacrylate groups, and most preferably methacrylate groups.

[0122] 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 0, 1, 2 or 3 and, if Sp is -O-(CH 2 ) p1 -, -O-CO-(CH 2 ) p1 or -CO-O-(CH 2 ) p1 , then the O-atom or the CO-group is attached to the benzene ring, respectively.

[0123] It is further preferred that at least one group Sp is a single bond.

[0124] It is further preferred that at least one group Sp is different from 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 each independently 0, 1, 2 or 3 and, if Sp is -O-(CH 2 ) p1 -, -O-CO-(CH 2 ) p1 or -CO-O-(CH 2 ) p1 , then the O-atom or the CO-group is attached to the benzene ring respectively.

[0125] Very preferably, Sp is different from 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 attached to the benzene ring.

[0126] Preferred compounds of formula IA are selected from the group consisting of formulas IA-1 to IA-10:

[0127]

[0128]

[0129] where alkyl and alkyl* each independently represent a straight-chain alkyl group having 1-6 C atoms, alkenyl and alkenyl* each independently represent a straight-chain alkenyl group having 2-6 C atoms, alkoxy and alkoxy* each independently represent a straight-chain alkoxy group having 1-6 C atoms, and L 1 and L 2 each independently represent F or Cl, preferably both are F.

[0130] Very preferably, it is the compound of formula IA-6.

[0131] Preferably, the LC medium contains 1, 2 or 3 compounds of formula IA or its sub-formulas.

[0132] Preferably, the total proportion of the compound of formula IA and its sub-formulas in the LC medium is > 5 - 25%, very preferably 7 - 20%, and most preferably 8 - 15% by weight.

[0133] The preferred compounds of formula IB are selected from the following sub-formulas:

[0134]

[0135]

[0136] wherein alkyl and alkyl* independently of one another represent a straight-chain alkyl group having 1 - 6 C atoms, preferably ethyl, n-propyl or n-butyl, and (O) represents an oxygen atom or a single bond, preferably an oxygen atom.

[0137] Very preferably, the compounds of formula IB-1 and IB-2, and most preferably the compound of formula IB-1, especially those wherein alkyl represents ethyl, n-propyl or n-butyl, preferably n-propyl, (O) represents an oxygen atom, and alkyl* represents ethyl, n-propyl or n-butyl, preferably ethyl.

[0138] Preferably, the LC medium contains 1, 2 or 3, very preferably 1 compound of formula IB or its sub-formulas.

[0139] Preferably, the total proportion of the compound of formula IB and its sub-formulas in the LC medium is 0.5 - 10% by weight, very preferably 1 - 10% by weight. In another preferred embodiment, the total proportion of the compound of formula IB and its sub-formulas in the LC medium is 2 - 8%, very preferably 2.5 - 7%.

[0140] The preferred compounds of formula IC are selected from the following sub-formulas:

[0141]

[0142]

[0143] Very preferably, the compounds of formula IC-1, IC-2, IC-3, IC-4, IC-5 and IC-6, and most preferably the compounds of formula IC-1 and IC-4.

[0144] Preferably, the LC medium contains 1, 2 or 3 compounds of formula IC or its sub-formulas.

[0145] Preferably, the total proportion of the compound of formula IC and its sub-formulas in the LC medium is 10 to 65% by weight, very preferably 15 to 55%, and most preferably 20 to 45% by weight.

[0146] The following lists further preferred embodiments of the LC medium according to the present invention, including any combination thereof:

[0147] The LC medium contains one or more compounds of formula II

[0148]

[0149] where each group, independently of one another and each time it occurs, is the same or different and has the following meanings

[0150] R 1 and R 2 is 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-, CR 0 =CR 00 -, -C≡C-, 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 or Cl, preferably an alkyl or alkoxy group having 1 to 6 C atoms,

[0151] R 0 , R 00 is H or an alkyl group having 1 to 12 C atoms,

[0152] A 1 and A 2 are groups selected from the following formulae

[0153]

[0154]

[0155] preferably formulae A1, A2, A3, A4, A5, A6, A9 and A10, very preferably formulae A1, A2, A3, A4, A5, A9 and A10,

[0156] 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,

[0157] L 1 , L 2 , L 3 and L 4 are F, Cl, OCF 3 , CF 3 , CH 3 , CH 2 F or CHF 2 , preferably F or Cl, very preferably F,

[0158] Y is H, F, Cl, CF 3 , CHF 2 or CH 3 , preferably H or CH 3 , very preferably H,

[0159] L C is CH 3 or OCH 3 , preferably CH 3 ,

[0160] a1 is 1 or 2,

[0161] a2 is 0 or 1.

[0162] Preferably, the LC medium contains one or more compounds of formula II, which are selected from compounds of formulae IIA, IIB, IIC and IID

[0163] Preferably, the LC medium contains one or more compounds of formula II, which are selected from compounds of formulae IIA, IIB, IIC and IID

[0164]

[0165] wherein

[0166] R 2A and R 2B each independently of one another represent H, an alkyl or alkenyl group having at most 15 C atoms, which is unsubstituted, monosubstituted by CN or CF 3 monosubstituted or at least monosubstituted by halogen, wherein additionally one or more CH 2 groups of 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 connected to one another,

[0167] L1 -L 4 each independently represents F, Cl, CF 3 or CHF 2 ,

[0168] Y represents H, F, Cl, CF 3 , CHF 2 or CH 3 , preferably H or CH 3 , particularly preferably H,

[0169] Z 2 , Z 2B and Z 2D each independently 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 -, -CF=CF-, -CH=CHCH 2 O-,

[0170] p represents 0, 1 or 2, and

[0171] q represents 0 or 1, the same or different each time it appears.

[0172] Preferred compounds of formulae IIA, IIB, IIC and IID are those in which R 2B 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.

[0173] Further preferred compounds of formulae IIA, IIB, IIC and IID are those in which R 2A or R 2B represents or contains a cycloalkyl or cycloalkoxy group, preferably selected from where S 1 is C 1-5 -alkylene or C 2-5 -alkenylene and S 2 is H, C 1-7 -alkyl or C 2-7 -alkenyl, and very preferably selected from

[0174] Further preferred compounds of formulae IIA, IIB, IIC and IID are as follows:

[0175] Further preferred compounds of formulae IIA, IIB, IIC and IID are as follows:

[0176]

[0177]

[0178]

[0179]

[0180]

[0181]

[0182]

[0183]

[0184]

[0185]

[0186] wherein the parameter a represents 1 or 2, alkyl and alkyl* each independently of one another represent straight-chain alkyl having 1-6 C atoms, and alkenyl represents straight-chain alkenyl having 2-6 C atoms, and (O) represents an oxygen atom or a single bond. 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 -.

[0187] Particularly preferred LC media according to the invention comprise one or more compounds of the formulae 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.

[0188] The proportion of the compounds of the formula IIA and / or IIB in the mixture is preferably at least 20 wt% as a whole.

[0189] In another preferred embodiment, the LC medium comprises one or more compounds of the formula III

[0190]

[0191] wherein

[0192] R 11 and R 12 each independently of one another represent H, an alkyl or alkoxy group having 1-15 C atoms, where one or more CH 2 groups may each independently of one another be replaced in such a way that O atoms are not directly connected to one another by -C≡C-, -CF 2 O-, -OCF 2 -, -CH=CH-, and are replaced by -O-, -CO-O- or -O-CO-, and wherein, furthermore, one or more H atoms may be replaced by halogen,

[0193] A 3 each occurrence independently of one another represents

[0194] a) 1,4-cyclohexenylene or 1,4-cyclohexylene, where one or two non-adjacent CH 2 groups may be replaced by -O- or -S-,

[0195] b) 1,4-phenylene, where one or two CH groups may be replaced by N, or

[0196] 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,

[0197] where the groups a), b) and c) may be mono- or polysubstituted by halogen atoms,

[0198] n represents 0, 1 or 2, preferably 0 or 1,

[0199] Z 1 each independently represents, each time it appears, -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

[0200] L 11 and L 12 each independently represents F, Cl, CF 3 or CHF 2 , preferably H or F, most preferably F, and

[0201] W represents O or S, and if n is 0, then W is not S.

[0202] In a preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III-1

[0203]

[0204] wherein the groups appearing have the same meanings as given under formula III above and preferably

[0205] R 11 and R 12 each independently has an alkyl, alkenyl or alkoxy group having at most 15 C atoms, more preferably one or both of them represent alkoxy and

[0206] L 11 and L 12 each preferably represents F.

[0207] In another preferred embodiment, the LC medium comprises one or more compounds of formula III-1 selected from compounds of formulae III-1-1 to III-1-11, preferably formula III-1-6

[0208]

[0209]

[0210] 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.

[0211] In another preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III2-1 and / or III2-2

[0212]

[0213] wherein L 11 and L 12 have the same meanings as given under formula III, (O) represents O or a single bond,

[0214] R IIIA represents an alkyl or alkenyl group having at most 7 C atoms, or the group Cy-C m H 2m+1 -,

[0215] 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

[0216] 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.

[0217] The compounds of formula III2-1 and / or III2-2 replace the compounds of formula III or are additionally contained in the LC medium, preferably additionally.

[0218] Very preferred compounds of formula III2-1 and III2-2 are as follows:

[0219]

[0220] wherein alkoxy represents a straight-chain alkoxy group having 1 to 6 C atoms.

[0221] In another preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III-3 to III-5, preferably formula III-4,

[0222]

[0223] wherein 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 to 7 C atoms.

[0224] In another preferred embodiment, the LC medium comprises one or more compounds of formula I, selected from the compounds of formulae III-6 to III-8, preferably formula III-7,

[0225]

[0226] wherein 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 to 7 C atoms.

[0227] In another preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III-9,

[0228]

[0229] wherein 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 to 7 C atoms.

[0230] Preferred compounds of formula III-9 are selected from formulae III-9-1 to III-9-10:

[0231]

[0232]

[0233] wherein R 12 represents an alkyl group having 1 to 7 C atoms, preferably ethyl, n-propyl or n-butyl, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl.

[0234] Preferred compounds of formula III-9 are selected from formulae III-9-1, III-9-2, III-9-3, III-9-4 and III-9-5, very preferably formulae III-9-2 and III-9-3, most preferably formula III-9-2, and in which all of the foregoing formulae R 12 is preferably ethyl, n-propyl or n-butyl, very preferably n-butyl.

[0235] In a preferred embodiment, the medium comprises one or more compounds of formula IV,

[0236]

[0237] wherein

[0238] R 41 represents an unsubstituted alkyl having 1 - 7 C atoms or an unsubstituted alkenyl having 2 - 7 C atoms, preferably an n-alkyl, particularly preferably having 2, 3, 4 or 5 C atoms, and

[0239] R 42 represents an unsubstituted alkyl having 1 - 7 C atoms or an unsubstituted alkoxy having 1 - 6 C atoms (both preferably having 2 - 5 C atoms), an unsubstituted alkenyl having 2 - 7 C atoms, preferably having 2, 3 or 4 C atoms, more preferably vinyl or 1-propenyl and especially vinyl.

[0240] wherein these compounds are different from formula IC.

[0241] The compounds of formula IV are preferably selected from the compounds of formulae IV-1 to IV-4,

[0242]

[0243] wherein

[0244] alkyl and alkyl’, independently of one another, represent an alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms,

[0245] alkenyl represents an alkenyl having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably 2 C atoms,

[0246] alkenyl’ represents an alkenyl having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms, and

[0247] alkoxy represents an alkoxy having 1 to 5 C atoms, preferably having 2 to 4 C atoms.

[0248] Preferably, the LC medium comprises one or more compounds selected from the compounds of formulae IV-1-1 to IV-1-4

[0249]

[0250] Very preferably, the LC medium according to the invention comprises one or more compounds of formula IV-2-1 and / or IV-2-2

[0251]

[0252] Very preferably, the LC medium according to the invention comprises a compound of formula IV-3, in particular selected from the compounds of formulae IV-3-1 and IV-3-2

[0253]

[0254] The LC medium preferably additionally contains one or more compounds of formula IVa,

[0255]

[0256] wherein

[0257] R 41 and R 42 each independently of one another represent a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkoxy group having at most 12 C atoms, and

[0258] represents

[0259] 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-.

[0260] Preferred compounds of formula IVa are as follows:

[0261]

[0262] wherein alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1 - 6 C atoms.

[0263] The LC medium according to the invention preferably contains at least one compound of formula IVa-1 and / or of formula IVa-2.

[0264] The proportion of the compound of formula IVa in the mixture as a whole is preferably at least 5 wt%.

[0265] Preferably, the LC medium contains one or more compounds of formulae IVb-1 to IVb-3

[0266]

[0267] wherein

[0268] alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1 - 6 C atoms, and

[0269] Alkenyl and alkenyl* each independently of one another represent a straight-chain alkenyl group having 2 to 6 C atoms.

[0270] The proportion of the biphenyls of the formulae IV-1 to IV-3 in the mixture is preferably at least 3 wt%, in particular ≥ 5 wt%, as a whole.

[0271] Among the compounds of the formulae IVb-1 to IVb-3, the compound of the formula IVb-2 is particularly preferred.

[0272] Particularly preferred biphenyls are

[0273]

[0274] wherein alkyl* represents an alkyl group having 1 to 6 C atoms and preferably represents n-propyl.

[0275] The LC medium according to the invention particularly preferably comprises one or more compounds of the formulae IVb-1-1 and / or IVb-2-3.

[0276] In a preferred embodiment, the LC medium comprises one or more compounds of the formula V

[0277]

[0278] wherein

[0279] R 51 and R 52 each independently of one another have one of the meanings given for R 41 and R 42 and preferably represent an alkyl group having 1 to 7 C atoms, preferably an n-alkyl group, particularly preferably an n-alkyl group having 1 to 5 C atoms, an alkoxy group having 1 to 7 C atoms, preferably an n-alkoxy group, particularly preferably an n-alkoxy group having 2 to 5 C atoms, an alkoxyalkyl, alkenyl or alkenyloxy group having 2 to 7 C atoms, preferably having 2 to 4 C atoms, preferably an alkenyloxy group,

[0280] identically or differently represent

[0281]

[0282] wherein

[0283] preferably represents

[0284] Z 51 ,Z 52 each independently of one another represent -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

[0285] n is 1 or 2.

[0286] The compound of formula V is preferably selected from the compounds of formulae V-1 to V-16:

[0287]

[0288]

[0289] wherein R 1 and R 2 have the meanings as defined above for R 51 described.

[0290] R 1 and R 2 each preferably independently of one another represent a straight-chain alkyl group having 1 to 6 C atoms or a straight-chain alkenyl group having 2 to 7 C atoms.

[0291] 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

[0292] The LC medium according to the invention very particularly preferably comprises compounds of formulae V-10, V-12, V-16 and / or IV-1, especially in an amount of 5-30%.

[0293] The preferred compound of formula V-10 is as follows:

[0294]

[0295]

[0296] The LC medium according to the invention particularly preferably comprises a combination of a tricyclic compound of formula V-10a and / or formula 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 and one or more compounds selected from the bicyclohexyl compounds of formula IV-1 is 5-40%, very particularly preferably 15-35%.

[0297] The very particularly preferred LC medium comprises compound V-10a and CC-2-3

[0298]

[0299] Compound V-10a and IV-1-1 are preferably present in the mixture at a concentration of 15-35%, particularly preferably 15-25% and most preferably 18-22%, based on the mixture as a whole.

[0300] A highly preferred LC medium contains compound V-10b and IV-1-1:

[0301]

[0302] Compound V-10b and IV-1-1 are preferably present in the mixture at a concentration of 15-35%, particularly preferably 15-25% and most preferably 18-22%, based on the mixture as a whole.

[0303] A highly preferred LC medium contains the following three compounds

[0304]

[0305] Compound V-10a, V-10b and IV-1-1 are preferably present in the mixture at a concentration of 15-35%, particularly preferably 15-25% and most preferably 18-22%, based on the mixture as a whole.

[0306] A preferred LC medium contains at least one compound selected from the following compounds

[0307]

[0308] wherein R 41 and R 42 , and R 51 and R 52 have the meanings as described above. Preferably in compounds V-6, V-7 and IV-1, R 41 and R 51 represent an alkyl or alkenyl having 1-6 or 2-6 carbon atoms respectively, and R 42 and R 52 represent an alkenyl having 2-6 carbon atoms.

[0309] A preferred LC medium contains at least one compound of formula V-6a, V-6b, V-7a, V-7b, IV-4-1, IV-4-2, IV-3a and IV-3b:

[0310]

[0311]

[0312] wherein alkyl represents an alkyl having 1-6 carbon atoms and alkenyl represents an alkenyl having 2-6 carbon atoms.

[0313] Compounds of formulae V-6a, V-6b, V-7a, V-7b, IV-4-1 and IV-4-2 are preferably present in the LC medium of the present invention in an amount of 1-40 wt%, preferably 5-35 wt% and very particularly preferably 10-30 wt%.

[0314] In a preferred embodiment of the present invention, the LC medium additionally comprises one or more compounds of formulae VI-1 to VI-9

[0315]

[0316]

[0317] wherein

[0318] R 7 each independently of one another has one of the meanings as defined for R in formula IIA, and 2A w and x each independently of one another represent 1-6.

[0319] Particularly preferred is an LC medium comprising at least one compound of formula V-9.

[0320] In a preferred embodiment of the present invention, the LC medium additionally comprises one or more compounds of formulae VII-1 to VII-25

[0321]

[0322]

[0323]

[0324]

[0325]

[0326]

[0327] wherein

[0328] R represents a straight-chain alkyl or alkoxy group having 1-6 C atoms, (O) represents -O- or a single bond, X represents F, Cl, OCF 3 or OCHF 2 x 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.

[0329] R preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy.

[0330] X preferably represents F or OCH 3 , very preferably F.

[0331] The LC medium of the present invention preferably contains terphenyls of formulae VII-1 to VII-25 in an amount of 2-30 wt%, especially 5-20 wt%.

[0332] Particularly preferred are compounds of formulae VII-1, VII-2, VII-4, VII-20, VII-21, and VII-22, wherein X represents F. In these compounds, R preferably represents an alkyl group and an alkoxy group, each having 1-5 C atoms. In the compound of formula VII-20, R preferably represents an alkyl group or an alkenyl group, especially an alkyl group. In the compound of formula VII-21, R preferably represents an alkyl group. In the compounds of formulae VII-22 to VII-25, X preferably represents F.

[0333] If the Δn value of the mixture ≥ 0.1, the terphenyls of formulae VII-1 to VII-25 are preferably used in the LC medium of the present invention. The preferred LC medium contains 2-20 wt% of one or more terphenyl compounds selected from the compounds of formulae VII-1 to VII-25.

[0334] Further preferred embodiments are listed below:

[0335] a) An LC medium containing at least one compound of formulae Z-1 to Z-7,

[0336]

[0337] wherein R, (O) and alkyl have the meanings as described above for formula III.

[0338] b) The preferred LC medium of the present invention contains one or more substances containing a tetrahydronaphthyl or naphthyl unit, such as compounds of formulae N-1 to N-5,

[0339]

[0340] wherein R 1N and R 2N each independently of one another have the meanings as described above for R 2A preferably represents a straight-chain alkyl group, a straight-chain alkoxy group or a straight-chain alkenyl group, and

[0341] Z 1 and Z 2 each independently of one another represent -C 2 H 4 -, -CH=CH-, -(CH 2 ) 4 -, -(CH 2 ) 3 O-, -O(CH2 ) 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.

[0342] c) The preferred LC medium contains one or more compounds selected from the group consisting of formula BC difluorodibenzochroman, formula CR chroman, and formula PH-1 and PH-2 fluorophenanthrene compounds,

[0343]

[0344]

[0345] wherein

[0346] R B1 , R B2 , R CR1 , R CR2 , R 1 , R 2 each independently of one another has the meaning of R 2A meaning. c is 0, 1 or 2. R 1 and R 2 preferably independently of one another represent an alkyl or alkoxy group having 1-6 C atoms.

[0347] The LC medium of the present invention preferably contains the compounds of formula BC, CR, PH-1, PH-2 in an amount of 3-20 wt%, especially in an amount of 3-15 wt%.

[0348] Particularly preferred compounds of formula BC and CR are compounds BC-1 to BC-7 and CR-1 to CR-5,

[0349]

[0350]

[0351] wherein

[0352] alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1-6 C atoms, and

[0353] alkenyl and

[0354] alkenyl* each independently of the other represents a straight-chain alkenyl having 2 to 6 C atoms.

[0355] Very particularly preferably, the LC medium comprises one, two or three compounds of the formulae BC-2, BF-1 and / or BF-2.

[0356] d) The preferred LC medium comprises one or more compounds of the formula In indane compounds,

[0357]

[0358] where

[0359] R 11 , R 12 ,

[0360] R 13 each independently of the other represents a straight-chain alkyl, alkoxy, alkoxyalkyl or alkenyl having 1 to 6 C atoms.

[0361] R 12 and R 13 additionally represent halogen, preferably F,

[0362] represents

[0363]

[0364] i represents 0, 1 or 2.

[0365] The preferred compounds of the formula In are the compounds of the formulae In-1 to In-16 described below:

[0366]

[0367]

[0368]

[0369] Particularly preferred are the compounds of the formulae In-1, In-2, In-3 and In-4.

[0370] The compounds of the formula In and the sub-formulae In-1 to In-16 are preferably used in the LC medium of the present invention at a concentration of ≥ 5 wt%, in particular 5 - 30 wt% and very particularly preferably 5 - 25 wt%.

[0371] e) The preferred LC medium additionally comprises one or more compounds of the formulae L-1 to L-5,

[0372]

[0373] wherein

[0374] R and R 1 each independently of one another have the meanings given above for R in formula IIA 2A and alkyl represents an alkyl group having 1 - 6 C atoms. The parameter s represents 1 or 2.

[0375] The compounds of formulae L - 1 to L - 5 are preferably used at a concentration of 5 - 50 wt%, in particular 5 - 40 wt% and very particularly preferably 10 - 40 wt%.

[0376] f) The preferred LC medium additionally comprises one or more compounds of formula IIA - Y

[0377]

[0378] wherein R 11 and R 12 have one of the meanings given above for R in formula IIA 2A and L 1 and L 2 identically or differently represent F or Cl.

[0379] The preferred compounds of formula IIA - Y are selected from the following sub - formulae

[0380]

[0381]

[0382] 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 -.

[0383] Particularly preferred compounds of formula IIA-Y are selected from the following sub-formulas:

[0384]

[0385] wherein Alkoxy and Alkoxy* have the meanings defined above and preferably represent methoxy, ethoxy, n-propoxy, n-butoxy or n-pentyloxy.

[0386] g) an LC medium additionally comprising one or more terphenyl compounds selected from the following formulas:

[0387]

[0388] wherein

[0389] 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 optionally fluorinated,

[0390] X Q is F, Cl, a haloalkyl or alkoxy having 1-6 C atoms or a haloalkenyl or alkenyloxy having 2-6 C atoms,

[0391] L Q1 -L Q6 are each independently H or F, where at least one of L Q1 -L Q6 is F.

[0392] 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.

[0393] 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 two of L Q3 , L Q4 and L Q1 and L Q2 are F.

[0394] Preferred compounds of formula Q are those in which X Q represents F or OCF 3 and are very preferably F.

[0395] Compounds of formula Q are preferably selected from the following sub-formulas

[0396]

[0397] wherein R Q has one of the meanings of formula Q or one of its preferred meanings given in the context, and is preferably ethyl, n-propyl or n-butyl.

[0398] Particularly preferred are compounds of formula Q1, especially those wherein R Q is n-propyl.

[0399] Preferably, the proportion of the compound of formula Q in the LC host mixture is >0 to ≤5 wt%, very preferably 0.05 - 2 wt%, more preferably 0.1 - 1 wt%, and most preferably 0.1 - 0.8 wt%.

[0400] Preferably, the LC medium contains 1 - 5, preferably 1 or 2 compounds of formula Q.

[0401] Adding the terphenyl compound of formula Q to the LC host mixture can reduce ODF non-uniformity, while maintaining high UV absorption, achieving fast and complete polymerization, generating a strong and fast tilt angle, and improving the UV stability of the LC medium.

[0402] In addition, adding a compound of formula Q having positive dielectric anisotropy to an LC medium having negative dielectric anisotropy can better control the dielectric constants ε || and ε ⊥ values, especially can achieve a high dielectric constant ε || value, and keep the dielectric anisotropy Δη constant, thereby reducing the recoil voltage and reducing image sticking.

[0403] The LC medium according to the present invention preferably comprises

[0404] - one or more compounds of formula IA or its sub-formulas, preferably formula IA-6, preferably in a concentration range of >5 to 25%, very preferably 6 to 20%, most preferably 7 to 15%;

[0405] - one or more compounds of formula IB or its sub-formulas, preferably formula IB-1 or IB-2, most preferably formula IB-1, preferably in a concentration range of 0.5 to 5%, very preferably 0.5 to 2%;

[0406] - one or more compounds of formula IC or its sub-formulas, preferably formula IC-1, IC-2, IC-3, IC-4, IC-5 or IC-6, very preferably formula IC-1 and / or IC-4, preferably in a concentration range of 10 to 70%, very preferably 15 to 55%, most preferably 20 to 45%;

[0407] - one or more compounds of formula IC-1, in a concentration range of 20 to 70%, very preferably 25 to 65%, most preferably 27 to 60%;

[0408] and / or

[0409] - one or more compounds of formulae IIA and IIB, preferably in a total concentration range of 30% to 45%;

[0410] and / or

[0411] - one or more compounds of formula IV, preferably in a total concentration range of 2% to 30%, more preferably 5% to 25%, particularly preferably 5% to 15%;

[0412] and / or

[0413] - one or more compounds of formula V-16, wherein preferably R 1 and R 2 are selected from ethyl and propyl, preferably in a total concentration range of 2% to 30%, more preferably 5% to 25%, particularly preferably 5% to 15%.

[0414] In particular, the medium comprises

[0415] - one or more compounds CY-n-Om, in particular CY-3-O4, CY-5-O4 and / or CY-3-O2, preferably in a total concentration range of 5% to 30%, preferably 10% to 20%;

[0416] - one or more compounds PY-n-Om, in particular PY-1-O2, PY-2-O2 and / or PY-3-O2, preferably in a total concentration range of 5% to 40%, preferably 10% to 30%;

[0417] and / or

[0418] - CPY-n-Om, in particular CPY-2-O2, CPY-3-O2 and / or CPY-5-O2, preferably at a concentration > 5%, in particular 7% to 20%, based on the entire mixture,

[0419] and / or

[0420] - 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 > 3%, in particular 5 to 15%, based on the entire mixture;

[0421] and / or

[0422] - CPY-n-Om and CY-n-Om, preferably at a concentration of 10 to 80%, based on the entire mixture,

[0423] and / or

[0424] -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 entire mixture.

[0425] The invention further relates to an active matrix addressed electro-optical display, characterized in that it contains a liquid crystal medium according to claim 1 as dielectric, and wherein the display is a VA, SA-VA, IPS, U-IPS, FFS, UB-FFS, SA-FFS, PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS, PS-positive-VA, PS-TN, polymer-stabilized SA-VA or polymer-stabilized SA-FFS display.

[0426] It is advantageous for the liquid crystal medium of the invention to preferably have a nematic phase of ≤ -20 °C to ≥ 70 °C, particularly preferably ≤ -30 °C to ≥ 80 °C, very particularly preferably ≤ -40 °C to ≥ 90 °C.

[0427] The medium of the invention has a clearing temperature of 70 °C or higher, preferably 74 °C or higher.

[0428] The expression "having a nematic phase" here means on the one hand that no smectic phase and no crystallization are observed at the corresponding temperature at low temperature and on the other hand that it does not become clear when heated from the nematic phase. The low-temperature studies are carried out in a flow viscosimeter at the corresponding temperature and are checked by storing in a test cell with a layer thickness corresponding to electro-optical use for at least 100 hours. If the storage stability in the corresponding test cell at a temperature of -20 °C is 1000 hours or more, the medium is called stable at this temperature. At temperatures of -30 °C and -40 °C, the response times are 500 hours and 250 hours respectively. At high temperature, the clearing point is measured in a capillary by conventional methods.

[0429] The liquid crystal mixture preferably has a nematic phase range of at least 60 K and a flow viscosity ν of at most 30 mm 2 ·s -1 at 20 °C. 20 .

[0430] 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.

[0431] The value of the birefringence Δn in the liquid crystal mixture is generally 0.07 - 0.16, preferably 0.08 - 0.15, very preferably 0.09 - 0.14.

[0432] In a preferred embodiment of the present invention, the birefringence of the medium is 0.090 - 0.110, preferably 0.095 - 0.105, particularly 0.100 - 0.105.

[0433] In another preferred embodiment, the medium of the present invention has a birefringence of 0.120 or higher, preferably 0.125 - 0.145, more preferably 0.130 - 0.140.

[0434] The liquid crystal mixture of the present invention has a dielectric anisotropy Δε of -1.5 to -8.0, preferably -2.0 to –4.0, particularly -2.5 to -3.5,

[0435] The rotational viscosity γ at 20 °C 1 is preferably ≤120 mPa·s, particularly ≤100 mPa·s.

[0436] In a preferred embodiment, the rotational viscosity γ at 20 °C 1 is ≤100 mPa·s, particularly ≤95 mPa·s.

[0437] The liquid crystal medium of the present invention has a relatively low value of the threshold voltage (V 0 ). They are preferably 1.7 V - 3.0 V, particularly preferably ≤2.7 V and very particularly preferably ≤2.5 V.

[0438] For the present invention, unless otherwise expressly stated, the term "threshold voltage" refers to the capacitive threshold (V 0 ), also known as the Freedericks threshold.

[0439] Furthermore, the liquid crystal medium according to the present invention has a high value of the voltage holding ratio in a liquid crystal cell.

[0440] Generally, liquid crystal media with a low addressing voltage or threshold voltage show a lower voltage holding ratio than those LC media with a higher addressing voltage or threshold voltage, and vice versa.

[0441] For the present invention, the term "dielectric positive compound" means a compound having Δε > 1.5, the term "dielectric neutral compound" means those having -1.5 ≤ Δε ≤ 1.5 and the term "dielectric negative compound" means those having Δε < -1.5. Here, the dielectric anisotropy of the compound is determined by dissolving 10% of the compound in the liquid crystal host in at least one test cell and measuring the capacitance of the resulting mixture. In each case, the test cell has a layer thickness of 20 μm and has vertical and planar surface alignments at 1 kHz. The measurement voltage is generally 0.5 V - 1.0 V, but is always lower than the capacitance threshold of the respective liquid crystal mixture under investigation.

[0442] All temperature values described in the present invention are in °C.

[0443] The LC media of the present invention are suitable for all VA-TFT (Vertical Alignment Thin Film Transistor) applications, such as VAN (Vertical Alignment Nematic), MVA (Multi-Domain VA), (S)-PVA (Super Patterned VA), ASV (Advanced Super View or Axially Symmetric VA), PSA (Polymer Stabilized VA), and PS-VA (Polymer Stabilized VA). In addition, they are also suitable for IPS (In-Plane Switching) and FFS (Fringe Field Switching) applications with negative Δε.

[0444] The nematic LC media in the displays of the present invention generally comprise two components A and B, which are themselves composed of one or more individual compounds.

[0445] Component A has a significant negative dielectric anisotropy and gives a dielectric anisotropy of the nematic phase of ≤ -0.5. In addition to one or more compounds of formula I, it preferably comprises compounds of formula IIA, IIB, and / or IIC, and one or more compounds of formula IV-1.

[0446] The proportion of component A is preferably 45 - 100%, especially 60 - 85%.

[0447] For component A, one or more individual compounds with a Δε value of ≤ -0.8 are preferably selected. The smaller the proportion of A in the overall mixture, the more negative this value will necessarily be.

[0448] Component B has distinct nematogeneity and a kinematic viscosity at 20 °C of not more than 30 mm 2 ·s -1 and preferably not more than 25 mm 2 ·s -1 .

[0449] Many suitable materials are known to those skilled in the art from the literature. Particularly preferred is the compound of formula O-17.

[0450] Particularly preferred individual compounds in component B are nematic liquid crystals with extremely low viscosity, having a kinematic viscosity at 20 °C of not more than 18 mm 2 ·s -1 and preferably not more than 12 mm 2 ·s -1 .

[0451] Component B is monotropically or enantiotropically nematic, has no smectic phase, and is capable of preventing the occurrence of a smectic phase in the LC medium at very low temperatures. For example, if various highly nematic materials are added to a smectic liquid crystal mixture, the nematic states of these materials can be compared by suppressing the degree of reaching the smectic phase.

[0452] The mixture may also optionally contain Component C, which comprises a compound having a dielectric anisotropy of Δε ≥ 1.5. These so-called positive compounds are usually present in a negative dielectric anisotropy mixture in an amount of ≤ 20 wt%, based on the mixture as a whole.

[0453] In addition to one or more compounds of formulae IA, IB, and IC, the medium preferably comprises 4 - 15, in particular 5 - 12, and particularly preferably < 10 compounds of formulae IIA, IIB, and / or IIC and optionally one or more compounds of formula IV-1.

[0454] In addition to the compounds of formulae IA, IB, and IC and the compounds of formulae IIA, IIB, and / or IIC and optionally IV-1 compounds, other components may also be present in an amount of up to 45%, but preferably up to 35%, in particular up to 10% of the mixture as a whole.

[0455] The other components are preferably selected from nematic or nematogenic substances, particularly from known substances of the following classes: azoxybenzene, benzylideneaniline, biphenyl, terphenyl, phenyl benzoate or cyclohexyl benzoate, phenyl cyclohexanecarboxylate or cyclohexyl cyclohexanecarboxylate, phenylcyclohexane, cyclohexylbiphenyl, cyclohexylcyclohexane, cyclohexylnaphthalene, 1,4-biscyclohexylbiphenyl or cyclohexylpyrimidine, phenyl dioxane or cyclohexyl dioxane, optionally halogenated stilbene, benzyl phenyl ether, diphenylacetylene, and substituted cinnamic acid esters.

[0456] The most important compounds suitable as components of a liquid crystal phase of this type can be characterized by the following formula IV

[0457] R 20 -L-G-E-R 21 IV

[0458] wherein L and E each independently represent a carbocyclic or heterocyclic system selected from the group consisting of: 1,4-disubstituted benzene rings and cyclohexane rings, 4,4'-disubstituted biphenyls, phenylcyclohexanes and cyclohexylcyclohexane systems, 2,5-disubstituted pyrimidines and 1,3-dioxane rings, 2,6-disubstituted naphthalenes, dihydronaphthalenes and tetrahydronaphthalenes, quinazolines and tetrahydroquinazolines,

[0459] G represents -CH=CH--N(O)=N-

[0460] -CH=CQ- -CH=N(O)-

[0461] -C≡C- -CH 2 -CH 2 -

[0462] -CO-O- -CH 2 -O-

[0463] -CO-S- -CH 2 -S-

[0464] -CH=N- -COO-Phe-COO-

[0465] -CF 2 O- -CF=CF-

[0466] -OCF 2 - -OCH 2 -

[0467] -(CH 2 ) 4 - -(CH 2 ) 3 O-

[0468] or a C-C single bond, Q represents a halogen, preferably chlorine or -CN, and R 20 and R 21 each represent an alkyl, alkenyl, alkoxy, alkoxyalkyl or alkoxycarbonyloxy group having at most 18, preferably at most 8 carbon atoms, or one of these groups represents CN, NC, NO 2 , NCS, CF 3 , SF 5 , OCF 3 , F, Cl or Br.

[0469] In most of these compounds, R 20 and R 21 are different from each other, and one of these groups is usually an alkyl or alkoxy group. Other variations of the proposed substituents are also common. Many such substances or their mixtures are also commercially available. All these substances can be prepared by methods known from the literature.

[0470] 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 are replaced by corresponding isotopes.

[0471] The combination of the compounds of the above-mentioned preferred embodiments with the above-mentioned polymeric compounds results in a low threshold voltage, low rotational viscosity and very good low-temperature stability in the LC medium of the present invention, while maintaining high-definition bright spots and high HR values, and allowing for the rapid establishment of a particularly low tilt angle (i.e., large tilt) in PSA displays. In particular, compared to LC media from the prior art, this LC medium exhibits a significantly shortened response time, especially the gray-scale response time, in PSA displays.

[0472] Preferably, the proportion of the polymerizable component A) in the LC medium is >0 to <5%, very preferably >0 to ≤1%, and most preferably 0.01 to 0.5%.

[0473] Preferably, the proportion of the LC component B) in the LC medium is 95 to <100%, very preferably 99 to <100%.

[0474] For use in PSA displays, the total proportion of the polymerizable compounds is preferably 0.01 to 2.0%, very preferably 0.1 to 1.0%, and most preferably 0.2 to 0.8%.

[0475] For use in SA-VA displays, the total proportion of the polymerizable compounds 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%.

[0476] The polymerizable compounds can be prepared analogously to methods known to those skilled in the art and described in standard works of organic chemistry, for example, in the methods described in Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], Thieme-Verlag, Stuttgart.

[0477] For example, acrylates or methacrylates can be prepared by the esterification of the corresponding alcohols with acid derivatives, such as (meth)acryloyl chloride or (meth)acrylic anhydride, in the presence of a base such as pyridine or triethylamine, and 4-(N,N-dimethylamino)pyridine (DMAP). Alternatively, the esters can be prepared by the esterification of the alcohols with (meth)acrylic acid in the presence of a dehydrating agent, such as dicyclohexylcarbodiimide (DCC) according to Steglich, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) or N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and DMAP.

[0478] The present invention also relates to an LC medium or an LC display as described above, wherein the polymerizable compounds of formulae I1, I2 and optionally I3 are present in a polymerized form.

[0479] The LC display is preferably a PS-VA, PS-IPS, PS-FFS or SA-VA display.

[0480] To produce a PSA or polymer-stabilized SA display, the polymerizable compounds contained in the LC medium are polymerized by in-situ polymerization in the LC medium between the LC display substrates, preferably while applying a voltage to the electrodes.

[0481] As described in the prior art cited at the beginning, the structure of the display according to the invention corresponds to the usual geometry of a PSA display. Geometries without protrusions are preferred, in particular those in which the electrodes on the color filter side are unstructured and only the electrodes on the TFT side have slots. Particularly suitable and preferred electrode structures for PS-VA displays are described, for example, in US 2006 / 0066793 A1.

[0482] The preferred PSA-type LC display according to the invention comprises:

[0483] - A first substrate comprising pixel electrodes defining pixel regions, the pixel electrodes being connected to switching elements provided in each pixel region and optionally including a micro-slit pattern, and optionally a first alignment layer provided on the pixel electrodes,

[0484] - 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,

[0485] - An LC layer provided between the first and second substrates and comprising an LC medium as described in the context, wherein the polymerizable compounds may also be present in polymerized form.

[0486] 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 vertical (or perpendicular) 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.

[0487] The LC layer having the LC medium can be deposited between the display substrates by methods conventionally used by display manufacturers, such as the so-called one-drop-filling (ODF) method. Then, the polymerizable components of the LC medium are polymerized, for example, by UV light polymerization. The polymerization can be carried out in one step, or in two or more steps.

[0488] The PSA display may include other elements such as color filters, black matrices, passivation layers, optical retardation layers, transistor elements for addressing individual pixels, etc., which are well known to those skilled in the art and can be used without creative skills.

[0489] The electrode structure can be designed by those skilled in the art according to each display type. For example, for a PS-VA display, the multi-domain alignment of LC molecules can be induced by providing electrodes with slits and / or protrusions or projections to produce two, four or more different tilt alignment directions.

[0490] After polymerization, the polymerizable compound forms a copolymer, resulting in a certain tilt angle of the LC molecules in the LC medium. Without being limited to a particular theory, it is believed that at least a part of the cross-linked polymer formed by the polymerizable compound will phase separate or precipitate from the LC medium and form a polymer layer on the substrate or electrode, or an alignment layer is provided thereon. Microscopic measurement data (such as SEM and AFM) have confirmed that at least a part of the formed polymer accumulates at the LC / substrate interface.

[0491] The polymerization can be carried out in one step. It is also possible to first carry out polymerization in a first step to produce a tilt angle, optionally while applying a voltage, and then polymerize or crosslink the unreacted compounds in a second polymerization step without applying a voltage ("final curing").

[0492] 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 irradiation.

[0493] The polymerizable compound is preferably selected from formula M

[0494] R a -B 1 -(Z b -B 2 ) m -R b M

[0495] wherein each group, each time it appears, is the same or different and each independently of one another has the following meanings:

[0496] R a and R b are P, P-Sp-, H, F, Cl, Br, I, -CN, -NO 2 、-NCO、-NCS、-OCN、-SCN、SF 5 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 each independently of one another be replaced by -C(R0 ) = C(R 00 )-, -C≡C-, -N(R 00 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- are replaced in such a way that O and / or S atoms are not directly connected to each other, and in addition, one or more H atoms can be replaced by F, Cl, Br, I, CN, P or P-Sp-, where, if B 1 and / or B 2 contains saturated C atoms, then R a and / or R b can also represent a group spiro-linked to the saturated C atom,

[0497] wherein at least one of the groups R a and R b represents or contains the group P or P-Sp-,

[0498] P is a polymerizable group,

[0499] Sp is a spacer group or a single bond,

[0500] B 1 and B 2 are aromatic, heteroaromatic, cycloaliphatic or heterocyclic groups having 4 to 25 ring atoms, which may also contain fused rings, and which are unsubstituted or mono- or polysubstituted by L,

[0501] Z b is -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-, -C≡C-, -CH = CH-COO-, -OCO-CH = CH-, CR 0 R 00 or a single bond,

[0502] R 0 and R 00each independently represents H or an alkyl group having 1 to 12 C atoms,

[0503] m represents 0, 1, 2, 3 or 4,

[0504] n1 represents 1, 2, 3 or 4,

[0505] L is 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 group, alkoxy group, alkylcarbonyl group, alkoxycarbonyl group, alkylcarbonyloxy group or alkoxycarbonyloxy group having 1 to 25 C atoms, where in addition, one or more H atoms may be replaced by F, Cl, P or P-Sp-,

[0506] P and Sp have the meanings indicated above,

[0507] Y 1 represents a halogen,

[0508] 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 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 each other, and where in addition, one or more H atoms may be replaced by F, Cl, P or P-Sp-, an optionally substituted aryl or aryloxy group having 6 to 40 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 40 C atoms.

[0509] Particularly preferred compounds of formula M are those in which B 1 and B 2 each independently represent 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, where in addition, one or more CH groups in these groups may be replaced by N, cyclohexane-1,4-diyl, where in addition, one or more non-adjacent CH 2The group may 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, where all of these groups may be unsubstituted or mono- or polysubstituted by L as described above.

[0510] Particularly preferred compounds of formula M are those in which B 1 and B 2 each independently of one another represent 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl.

[0511] Further preferred are polymerizable compounds selected from the following formulas:

[0512]

[0513]

[0514]

[0515]

[0516]

[0517] where each occurrence of each group is the same or different and each independently of one another has the following meanings:

[0518] P 1 ,P 2 ,P 3 is a polymerizable group, preferably selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy.

[0519] Sp 1 ,Sp 2 ,Sp 3 is a single bond or a spacer group, where additionally, one or more of the groups P 1 -Sp 1 -, P 1 -Sp 2 - and P 3 -Sp 3 - may represent R aa , provided that the groups P 1 -Sp 1 -, P 2 -Sp 2 and P3 -Sp 3 At least one of them is different from R aa , 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,

[0520] R aa is H, F, Cl, CN or a straight-chain or branched alkyl group having 1 to 25 C atoms, where additionally, one or more non-adjacent CH 2 groups can each be independently 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 connected to each other, and where additionally, one or more H atoms can be replaced by F, Cl, CN or P 1 -Sp 1 - substituted, 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 (where alkenyl and alkynyl groups have at least two C atoms and branched groups have at least three C atoms), and where R aa does not represent or contain the group P 1 , P 2 or P 3 ,

[0521] R 0 ,R 00 is H or an alkyl group having 1 to 12 C atoms,

[0522] R y and R z are H, F, CH 3 or CF 3 ,

[0523] X 1 ,X 2 ,X 3 is -CO-O-, -O-CO- or a single bond,

[0524] Z M1 is -O-, -CO-, -C(R y Rz ) - or - CF 2 CF 2 -,

[0525] Z M2 , Z M3 is - 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,

[0526] L is F, Cl, CN or a straight - chain or branched - chain, optionally mono - or poly - fluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 - 12 C atoms,

[0527] L', L" are H, F or Cl,

[0528] k is 0 or 1,

[0529] r is 0, 1, 2, 3 or 4,

[0530] s is 0, 1, 2 or 3,

[0531] t is 0, 1 or 2,

[0532] x is 0 or 1.

[0533] Compounds of formula M2 and M13 are very preferably, especially those exactly containing two polymerizable groups P 1 and P 2 of the bireactive compounds.

[0534] Compounds selected from formulae M17 - M32 are further preferably, especially formulae M20, M22, M24, M27, M30 and M32, especially those exactly containing three polymerizable groups P 1 , P 2 and P 3 of the tri - reactive compounds.

[0535] Among the compounds of formula M1 - M31

[0536] preferably

[0537]

[0538] where L, each time it appears, is the same or different and has one of the meanings given in the context, and is preferably F, Cl, CN, NO 2 , CH3 , C 2 H 5 , C(CH 3 ) 3 , CH(CH 3 ) 2 , CH 2 CH(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 or P-Sp-, very preferably F, Cl, CN, CH 3 , C 2 H 5 , OCH 3 , COCH 3 , OCF 3 or P-Sp-, more preferably F, Cl, CH 3 , OCH 3 , COCH 3 or OCF 3 , most preferably F or OCH 3 .

[0539] Preferred compounds of formulas M1 - M32 are those 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.

[0540] Further preferred compounds of formulas M1 - M32 are those in which Sp 1 , Sp 2 and Sp 3 are single bonds.

[0541] Further preferred compounds of formulas M1 - M32 are those in which one of Sp 1 , Sp 2 and Sp 3 is a single bond and Sp 1 , Sp 2 and Sp3 and those different from single bonds among them.

[0542] Further preferred compounds of formula M1-M32 are those in which the group Sp different from single bonds 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 connected to the benzene ring and is -O-, -O-CO-, -CO-O, -O-CO-O- or a single bond.

[0543] Further preferred compounds of formula M are those selected from Table D below, especially those selected from formula 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-64, RM-74, RM-76, RM-88, RM-92, RM-102, RM-103, RM-109, RM-116, RM-117, RM-120, RM-121, RM-122, RM-139, RM-142, RM-153, RM-155, RM-158 and RM-159.

[0544] Particularly preferred LC media contain one, two or three polymerizable compounds of formula M.

[0545] Further preferred LC media contain two or more bis-reactive polymerizable compounds of formula M, preferably selected from formula M1-M16, very preferably selected from formula M2 and M13.

[0546] Further preferred LC media contain one or more bis-reactive polymerizable compounds of formula M, preferably selected from formula M1-M16, very preferably formula M2 and M13, and one or more tri-reactive polymerizable compounds of formula M, preferably selected from M17-M32, very preferably formula M20, M22, M24, M27, M30 and M32.

[0547] Further preferred LC media contain 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, very preferably selected from formula M2, M13, M22, M24, M27, M30 and M32, and where L is selected from the preferred groups shown above, most preferably F and OCH 3 .

[0548] Further preferred are polymerizable compounds which show absorption at wavelengths of 340 - 380 nm, preferably selected from formula M, very preferably from formulas M1 - M32, and most preferably selected from the group consisting of the above formulas of Table D.

[0549] 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 the person skilled in the art and are described in the literature. Suitable for free radical polymerization are, for example, commercially available photoinitiators or (Ciba AG). If a polymerization initiator is used, its proportion is preferably 0.001 - 5 wt%, particularly preferably 0.001 - 1 wt%.

[0550] The polymerizable compounds of the invention are also suitable for polymerization without an initiator, which has considerable advantages, such as lower material costs, in particular the LC medium is less contaminated by possible residual amounts of initiator or its degradation products. Therefore, polymerization can also be carried out without adding an initiator. Thus, in a preferred embodiment, the LC medium does not contain a polymerization initiator.

[0551] The LC medium may also contain one or more stabilizers to prevent, for example, undesired spontaneous polymerization of the RM during storage or transport. Suitable types and amounts of stabilizers are known to the person skilled in the art and are described in the literature. Particularly suitable are, for example, commercially available stabilizers of 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 10 - 50,000 ppm, particularly preferably 50 - 5,000 ppm.

[0552] In a preferred embodiment, the LC medium contains one or more chiral dopants, preferably at a concentration of 0.01 - 1 wt%, very preferably 0.05 - 0.5 wt%. The chiral dopants are preferably selected from the compounds of Table B below, very preferably R - or S - 1011, R - or S - 2011, R - or S - 3011, R - or S - 4011, and R - or S - 5011.

[0553] In another preferred embodiment, the LC medium contains a racemate of one or more chiral dopants, which are preferably selected from the chiral dopants mentioned in the previous paragraph.

[0554] In another preferred embodiment of the invention, the LC medium contains one or more other stabilizers, preferably selected from the following formula

[0555]

[0556] Each group is independent of one another and, each time it appears, has the following meaning, being the same or different

[0557] R a-d is a straight-chain or branched alkyl group having 1 to 10, preferably 1 to 6, very preferably 1 to 4 C atoms, most preferably methyl

[0558] X S is H, CH 3 , OH or O ● ,

[0559] A S is a straight-chain, branched or cycloalkylidene group having 1 to 20 C atoms, which is optionally substituted

[0560] n is an integer from 1 to 6, preferably 3

[0561] Preferred stabilizers of formula S3 are selected from formula S3A

[0562]

[0563] wherein n2 is an integer from 1 to 12, and wherein one or more H atoms in the group (CH 2 ) n2 are optionally replaced by methyl, ethyl, propyl, butyl, pentyl or hexyl

[0564] Very preferred stabilizers are selected from the following formula

[0565]

[0566]

[0567]

[0568] In a preferred embodiment, the liquid crystal medium comprises one or more stabilizers selected from formulas S1-1, S2-1, S3-1, S3-1 and S3-3

[0569] In a preferred embodiment, the liquid crystal medium comprises one or more stabilizers selected from Table C below

[0570] Preferably, the proportion of stabilizers in the liquid crystal medium, such as those of formulas S1-S3, is 10-500 ppm, very preferably 20-100 ppm

[0571] In another preferred embodiment, the LC medium of the present invention contains a self-aligning (SA) additive, preferably at a concentration of 0.1-2.5%

[0572] In another preferred embodiment, the LC medium of the present invention contains a self-aligning (SA) additive, preferably at a concentration of 0.1 - 2.5%.

[0573] In a preferred embodiment, the SA-VA display of 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.

[0574] Preferred SA additives for this preferred embodiment are selected from compounds comprising a mesogenic group and a linear or branched alkyl side chain terminated with one or more polar anchoring groups selected from hydroxy, carboxy, amino or thiol groups.

[0575] 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 similar conditions to those used for RM in the PSA process.

[0576] Suitable SA additives for inducing vertical alignment, especially for SA-VA mode displays, are disclosed in, for example, US 2013 / 0182202 A1, US 2014 / 0838581 A1, US 2015 / 0166890 A1 and US 2015 / 0252265 A1.

[0577] In another preferred embodiment, the LC medium or polymer-stabilized SA-VA display of the present invention contains one or more self-aligning additives selected from Table E below.

[0578] In another preferred embodiment, the LC medium of the present invention contains one or more SA additives, preferably selected from Formula II or its sub-formulas or from Table E, at a concentration of 0.1 - 5%, very preferably 0.2 - 3%, and most preferably 0.2 - 1.5%.

[0579] In another preferred embodiment, the LC medium and display according to the present invention do not contain self-aligning additives, especially they do not contain compounds selected from Table E below.

[0580] A preferred embodiment of the present invention relates to a method for preparing a PSA display as described in the context, the method comprising one or more of the following features:

[0581] - In a two-step process, irradiating a polymerizable LC medium with UV light, including a first UV exposure step ("UV1 step"), applying a voltage to generate an inclination angle, and a second UV exposure step ("UV2 step"), without applying a voltage to complete the polymerization,

[0582] - With an intensity of 0.5 mW / cm2 -10 mW / cm 2 The UV light irradiation generated by a UV lamp with a wavelength of 300 - 380 nm irradiates the polymerizable LC medium, preferably in the UV2 step, and optionally also in the UV1 step.

[0583] - Irradiating the polymerizable LC medium with UV light having a wavelength ≥ 340 nm, and preferably ≤ 420 nm, very preferably 340 - 380 nm, more preferably 350 to < 370 nm, and most preferably 355 - 368 nm.

[0584] - While applying a voltage to the electrodes of the display, irradiating the polymerizable LC medium with UV light.

[0585] - Using a UV - LED lamp for UV light irradiation.

[0586] For example, this preferred method can be carried out by using the required UV lamp or by using a band - pass filter and / or a cut - off filter, which are substantially transmissive for UV light having each required wavelength and substantially light - blocking for each undesired wavelength. For example, when UV light with a wavelength λ of 300 - 400 nm is required for irradiation, a broadband filter that is substantially transmissive for wavelengths 300 nm < λ < 400 nm can be used for UV exposure. When UV light with a wavelength λ greater than 340 nm is required for irradiation, a cut - off filter that is substantially transmissive for wavelengths λ > 340 nm can be used for UV irradiation.

[0587] Preferably, a UV - LED lamp is used for UV irradiation.

[0588] In the PSA method, using a UV - LED lamp with only one narrow emission peak offers multiple advantages. For example, it can more effectively transfer light energy to the polymerizable compounds in the LC medium, depending on the selection of suitable polymerizable compounds that show absorption at the LED lamp emission wavelength. This allows for a reduction in UV intensity and / or UV irradiation time, thus enabling a shorter cycle time and saving energy and production costs. Another advantage is that the emission spectrum of the lamp is narrow, making it easier to select a suitable wavelength for photopolymerization.

[0589] Very preferably, the UV light source is a UV - LED lamp with an emission wavelength of 340 - 400 nm, more preferably 340 - 380 nm. Particularly preferably, a UV - LED lamp that emits UV light with a wavelength of 365 nm.

[0590] This preferred method enables the manufacture of a display by using a longer UV wavelength, thereby reducing or even avoiding the harmful and destructive effects of short UV components.

[0591] The UV irradiation energy is generally 6 - 100 J, depending on the production process conditions.

[0592] The LC medium of the present invention may additionally contain one or more other components or additives, preferably selected from the following list, 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.

[0593] Further additives may be polymerizable or non-polymerizable. Polymerizable additives are accordingly assigned to the polymerizable components or component A). Accordingly, non-polymerizable additives are assigned to the non-polymerizable components or component B).

[0594] The LC medium preferably has a nematic LC phase.

[0595] In addition, for example, 0 to 15% by weight of a dichroic dye can be added to the LC medium, and in addition, nanoparticles, a conductive salt, preferably ammonium ethyl dimethyl dodecyl 4-hexyloxybenzoate, ammonium tetrabutyltetraphenylborate, or a complex salt of a crown ether (see, for example, Haller et al., Mol. Cryst. Liq. Cryst. 24 , 249 - 258 (1973)) can be added 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.

[0596] The individual components of the above-listed preferred embodiments of the LC medium according to the present invention are known, or the methods for preparing them can be obtained by those skilled in the relevant art from the prior art, because 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 in DE-A-26 36 684 and DE-A-33 21 373.

[0597] The LC medium that can be used according to the present invention can be prepared by a method conventional 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. Generally, the desired amounts of the components used in smaller amounts are dissolved in the components constituting 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 present invention also relates to a method for preparing the LC medium according to the present invention.

[0598] It is self - evident to those skilled in the art that the LC medium according to the present invention may also contain, for example, compounds in which H, N, O, Cl, F are replaced by the corresponding isotopes such as deuterium.

[0599] The following examples illustrate the present invention but do not limit it. However, they show those skilled in the art the preferred mixture concepts, 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 achievable. The preferred mixture components are shown in Table A below.

[0600] Table A

[0601] In Table A, m and n are independently integers from 1 to 12, preferably 1, 2, 3, 4, 5 or 6, k is 0, 1, 2, 3, 4, 5 or 6, and (O)C m H 2m+1 represents C m H 2m+1 or OC m H 2m+1 .

[0602]

[0603]

[0604]

[0605]

[0606]

[0607]

[0608]

[0609]

[0610]

[0611]

[0612]

[0613]

[0614]

[0615]

[0616]

[0617]

[0618]

[0619]

[0620]

[0621]

[0622]

[0623] In a first preferred embodiment of the present invention, the LC medium of the present invention, in particular those having positive dielectric anisotropy, comprises one or more compounds selected from the compounds of Table A1.

[0624] In a second preferred embodiment of the present invention, the LC medium according to the present invention, in particular those having negative dielectric anisotropy, comprises one or more compounds selected from the compounds of Table A2.

[0625] Table B

[0626] Table B shows the chiral dopants that can be added to the LC medium of the present invention.

[0627]

[0628]

[0629] The LC medium preferably comprises 0 - 10 wt%, in particular 0.01 - 5 wt%, particularly preferably 0.1 - 3 wt% of the dopant. The LC medium preferably comprises one or more dopants selected from the compounds of Table B.

[0630] Table C

[0631] Table C shows the possible stabilizers that can be added to the LC medium of the present invention. Here 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.

[0632]

[0633]

[0634]

[0635]

[0636]

[0637]

[0638]

[0639] The LC medium preferably contains 0 - 10 wt%, especially 1 ppm - 5 wt%, and particularly preferably 1 ppm - 1 wt% of a stabilizer. The LC medium preferably contains one or more stabilizers selected from the compounds in Table C.

[0640] Table D

[0641] Table D shows exemplary reactive mesogenic compounds that can be used in the LC medium of the present invention.

[0642]

[0643]

[0644]

[0645]

[0646]

[0647]

[0648]

[0649]

[0650]

[0651]

[0652]

[0653]

[0654]

[0655]

[0656]

[0657]

[0658]

[0659]

[0660]

[0661]

[0662]

[0663] In a preferred embodiment, the mixture of the present invention comprises one or more polymerizable compounds, preferably selected from the polymerizable compounds of formulae RM-1 to RM-144. Among these, the 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-64, RM-74, RM-76, RM-88, RM-102, RM-103, RM-109, RM-117, RM-120, RM-121, RM-122 and RM-145 to RM-152 are particularly preferred.

[0664] In another preferred embodiment, the mixture of the present invention comprises one or more polymerizable compounds selected from the polymerizable compounds of formulae RM-145 to RM-152, very preferably of formulae RM-147 to RM-152.

[0665] Table E

[0666] Table E shows the self-aligning additives for vertical alignment, which can be used together with the polymerizable compound of formula I in the LC medium of the SA-VA and SA-FFS displays of the present invention:

[0667]

[0668]

[0669]

[0670]

[0671]

[0672]

[0673]

[0674]

[0675]

[0676]

[0677]

[0678] In a preferred embodiment, the LC medium of the SA-VA and SA-FFS displays of the present invention comprises one or more SA additives selected from SA-1 to SA-48 of the formula (preferably selected from SA-14 to SA-48, very preferably SA-20 to SA-34 and SA-44) and one or more RMs of the formula I. Detailed Description of the Invention

[0679] Example

[0680] The following examples illustrate the invention without limiting it. However, they show to those skilled in the art the concept of preferred mixtures and the compounds preferably used and their respective concentrations and their combinations with each other. Additionally, the examples illustrate the properties and combinations of properties that can be obtained.

[0681] Additionally, the following abbreviations and symbols are used:

[0682] V 0 represents the threshold voltage at 20 °C, capacitive [V],

[0683] n e represents the extraordinary refractive index at 20 °C and 589 nm,

[0684] n o represents the ordinary refractive index at 20 °C and 589 nm,

[0685] Δn represents the optical anisotropy at 20 °C and 589 nm,

[0686] ε ⊥ represents the dielectric constant perpendicular to the director at 20 °C and 1 kHz,

[0687] ε || represents the dielectric constant parallel to the director at 20 °C and 1 kHz,

[0688] Δε represents the dielectric anisotropy at 20 °C and 1 kHz,

[0689] cl.p., T(N,I) represents the clearing point [°C],

[0690] γ 1 represents the rotational viscosity at 20 °C [mPa·s],

[0691] K 1 represents the elastic constant at 20 °C, "tilt" deformation [pN],

[0692] K 2Denotes the elastic constant at 20 °C, "twist" deformation [pN],

[0693] K 3 Denotes the elastic constant at 20 °C, "bend" deformation [pN].

[0694] Unless otherwise explicitly stated, all concentrations in this application are given as weight percentages and relate to the corresponding entire mixture, which contains all solid or liquid crystal components (without solvent).

[0695] Unless otherwise stated, 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. denotes the melting point, cl.p. = clearing point. Furthermore, C = liquid crystal phase, N = nematic phase, S = smectic phase, and I = isotropic phase. The data between these symbols represent the transition temperatures.

[0696] 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.

[0697] 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 stated. In the examples, the optical threshold is also given as usual for a relative contrast of 10% (V 10 ).

[0698] Unless otherwise stated, 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.

[0699] Unless otherwise stated, the method of preparing test cells and measuring their electro-optical and other properties is carried out by the method described below or a similar method.

[0700] The display for measuring the capacitive threshold voltage consists of two planar parallel glass outer plates spaced 25 μm apart, each outer plate having an electrode layer on the inside and an unrubbed polyimide alignment layer on the top, which results in a vertical edge alignment of the liquid crystal molecules.

[0701] The PSVA display or PSVA test cell for measuring the tilt angle consists of two planar parallel glass outer plates spaced 4 μm apart. Unless otherwise specified, each of the outer plates has an electrode layer on the inner side and a polyimide alignment layer on top, where the two polyimide layers are rubbed antiparallel to each other and result in a vertical edge alignment of the liquid crystal molecules. The SAVA display or test cell has the same structure, but one or two polyimide layers are omitted therein.

[0702] The polymerizable compound is polymerized in the display or test cell by irradiating with UV light of a defined intensity for a predetermined time while applying a voltage (usually 10V - 30V alternating current, 1kHz) to the display. In the examples, unless otherwise specified, a metal halide or high-pressure Hg lamp and an intensity of 50 to 100 mW / cm 2 are used for polymerization. The intensity is measured using a standard meter (Hoenle UV-meter high end with a UV sensor).

[0703] The tilt angle is measured using the Mueller Matrix Polarimeter “AxoScan” from Axometrics. A small value (i.e., a large deviation from the 90° angle) corresponds to a large tilt here.

[0704] 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 major axis of the LC molecules in a layer of LC molecules with uniform orientation, which corresponds to the molecular long axis in the case of rod-shaped, uniaxial positive birefringent LC molecules.

[0705] Comparative Example 1

[0706] The nematic LC host mixture C1 is formulated as follows

[0707]

[0708]

[0709] This mixture contains the compounds B(S)-2O-O4 and B(S)-2O-O5 of formula IA and the compounds CC-3-V and CC-3-V1 of formula IC, but does not contain the compounds of formula IB.

[0710] Example 1

[0711] The nematic LC host mixture N1 is formulated as follows

[0712]

[0713] The mixture contains the compounds of formula IA, B(S)-2O-O4 and B(S)-2O-O5, the compound of formula IB, CLY-3-O2 and the compounds of formula IC, CC-3-V and CC-3-V1.

[0714] Comparative Example 2

[0715] The nematic LC host mixture C2 is formulated as follows

[0716]

[0717]

[0718] The mixture contains the compounds of formula IA, B(S)-2O-O4, B(S)-2O-O5 and B(S)-2O-O6 and the compounds of formula IC, CC-3-V and CC-3-V1, but does not contain the compound of formula IB.

[0719] Example 2

[0720] The nematic LC host mixture N2 is formulated as follows

[0721]

[0722] The mixture contains the compounds of formula IA, B(S)-2O-O4, B(S)-2O-O5 and B(S)-2O-O6, the compound of formula IB, CLY-3-O2 and the compounds of formula IC, CC-3-V and CC-3-V1.

[0723] Polymerizable mixture

[0724] The polymerizable mixture is prepared by adding the polymerizable compound M1 and the stabilizer S1 to the nematic LC host mixture as described above. The polymerizable mixture composition is shown in Table 1 below.

[0725] Table 1 - Polymerizable mixture composition

[0726] Mixture PC1 P1 PC2 P2 Main body C1 N1 C2 N2 ％M1 0.4 0.4 0.4 0.4 ％S1 0.005 0.005 0.005 0.005

[0727]

[0728] VHR

[0729] The VHR of the polymerizable mixture is measured as follows: at 60 °C with a voltage of 1 V / 60 Hz, before and after UV irradiation for a certain period of time, and after a certain period of time with a backlight load (BL).

[0730] Optical stress usually leads to a decrease in VHR in the LC mixture. Therefore, the smaller the absolute decrease in the VHR value after stress, the better the performance of the display application. The results are shown in Table 2.

[0731] Table 2 – VHR

[0732]

[0733]

[0734] As can be seen from Table 2, the VHR values of the polymerizable mixtures P1 and 2 according to the present invention are significantly higher compared to the polymerizable reference mixtures PC1 and PC2.

[0735] Tilt stability

[0736] Tilt stability, i.e., the change in the tilt angle after repeated electrical stress, is a criterion for evaluating the risk of image sticking. A low value of the change in the tilt angle indicates high tilt stability and a low potential risk of image sticking.

[0737] To determine the tilt stability, the polymerizable mixture is polymerized in a VA-tilt test cell having a cell thickness of approximately 4 μm and two substrates having antiparallel rubbed polyimide layers (JALS-2096-R1), by using a high-pressure Hg lamp at room temperature with 50 mW / cm 2 and 14 V PP and 60 Hz of applied square-wave voltage for 6 J of UV exposure. Initially, after electrical stress with a square-wave voltage of 60 V PP and 60 Hz for 72 hours and 24 hours after releasing the electrical stress, the tilt angle is measured using Axometrics The change in the tilt angle Δtilt is determined according to the following equation.

[0738] Tilt 在应力后 – Tilt 在倾斜角生成后 = Δtilt

[0739] And is shown in Table 3 below. The lower the value of Δtilt, the higher the tilt stability.

[0740] Table 3 - Tilt stability

[0741]

[0742] 1) After electrical stress

[0743] 2) After release (24 h after electrical stress)

[0744] As can be seen from Table 3, the polymerizable mixtures P1 and P2 according to the invention show good tilt stability similar to or even better than that of the polymerizable reference mixtures PC1 and PC2.

Claims

1. An LC medium, comprising a polymerizable component A), which comprises one or more polymerizable compounds, wherein the polymerizable compound comprises a compound of formula M2 or formula M13: wherein each group, each time it appears, is the same or different and each independently of one another has the following meanings: P 1 ,P 2 is ethenyloxy group, acrylate group, methacrylate group, fluoroacrylate group, chloroacrylate group, oxetanyl group or epoxy group, Sp 1 ,Sp 2 is a single bond or a spacer group, wherein additionally, the group P 1 -Sp 1 - and P 1 -Sp 2 - one or more of which may also represent R aa , provided that the group P 1 -Sp 1 - and P 2 -Sp 2 at least one of which is different from R aa , R aa is H, F, Cl, CN or a straight-chain or branched alkyl group having 1 to 25 C atoms, where additionally, one or more non-adjacent CH 2 groups may 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-, and where additionally, one or more H atoms may be replaced by F, Cl, CN or P 1 -Sp 1 - R 0 ,R 00 is H or an alkyl group having 1 to 12 C atoms, L is F, Cl, CN or a straight-chain or branched-chain, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 12 C atoms, r is 0, 1, 2, 3 or 4, and a liquid crystal component B), hereinafter also referred to as "LC host mixture", comprising one or more mesogenic or liquid crystal compounds, wherein component B) comprises one or more compounds of formula IA as defined below, one or more compounds of formula IB and one or more compounds of formula IC wherein each group, each time it appears, is the same or different and each independently of one another has the following meanings: R 1 , R 2 is a straight-chain, branched-chain or cyclic alkyl group having 1 to 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-, CR 0 =CR 00 -, -C≡C-, substituted 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 or Cl, R 0 ,R 00 is H or an alkyl group having 1 to 12 carbon atoms, L 1 where L 2 is F or Cl, alkyl is an alkyl group having 1 to 7 carbon atoms, alkenyl is an alkenyl group having 2 to 5 C atoms, wherein, the proportion of the compound of formula IA in component B) of the LC medium is 7-20% by weight, wherein the LC medium has a negative dielectric anisotropy, and the proportion of the compound of formula IB is 0.5-10%.

2. The LC medium according to claim 1, characterized in that the LC medium has a negative dielectric anisotropy of -1.5 to -8.

0.

3. The LC medium according to claim 1 or 2, characterized in that the compound of formula IA is selected from formulae IA-1 to IA-10: 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 1 and L 2 each independently of one another represent F or Cl.

4. The LC medium according to claim 1 or 2, characterized in that the compound of formula IB is selected from the following sub-formulae: wherein alkyl and alkyl* independently of one another represent a straight-chain alkyl group having 1-6 C atoms and (O) represents an oxygen atom or a single bond.

5. The LC medium according to claim 1 or 2, characterized in that the compound of formula IC is selected from formulae IC-1 to IC-12:

6. The LC medium according to claim 1 or 2, characterized in that it additionally contains one or more compounds of formula II wherein each group, independently of one another and each time it appears, is the same or different and has the following meanings R 1 and R 2 is 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-, CR 0 =CR 00 -, -C≡C-, substituted 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 or Cl, R 0 ,R 00 is H or an alkyl group having 1 to 12 C atoms A 1 and A 2 is a group selected from the following formula 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 L 1 ,L 2 ,L 3 and L 4 are F, Cl, OCF 3 ,CF 3 ,CH 3 ,CH 2 F or CHF 2 , Y is H, F, Cl, CF 3 , CHF 2 or CH 3 , L C is CH 3 or OCH 3 , a1 is 1 or 2, a2 is 0 or 1.

7. The LC medium according to claim 1 or 2, characterized in that it contains one or more compounds of formula II selected from formulae IIA, IIB, IIC and IID wherein R 2A and R 2B each independently of one another represent H, an alkyl or alkenyl group having at most 15 C atoms, which is unsubstituted, substituted by CN or CF 3 monosubstituted or at least monosubstituted by halogen, where additionally one or more CH 2 groups may 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 connected to one another L 1 to L 4 each independently represents F, Cl, CF 3 or CHF 2 , Y represents H, F, Cl, CF 3 , CHF 2 or CH 3 , Z 2 , Z 2B and Z 2D each independently 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 -, -CF=CF-, -CH=CHCH 2 O- p represents 0, 1 or 2, and q, each time it appears, is the same or different and represents 0 or 1.

8. The LC medium according to claim 1 or 2, characterized in that it additionally comprises one or more compounds of formula IV wherein R 41 represents an unsubstituted alkyl group having 1 to 7 carbon atoms or an unsubstituted alkenyl group having 2 to 7 carbon atoms, and R 42 represents an unsubstituted alkyl group having 1 - 7 C atoms or an unsubstituted alkoxy group having 1 - 6 C atoms, or an unsubstituted alkenyl group having 2 - 7 C atoms.

9. The LC medium according to claim 1 or 2, characterized in that it additionally comprises one or more compounds of formula V wherein R 51 and R 52 each independently represents an unsubstituted alkyl group having 1 to 7 carbon atoms or an unsubstituted alkoxy group having 1 to 6 carbon atoms, or an unsubstituted alkenyl group having 2 to 7 carbon atoms, Represented identically or differently Z 51 , Z 52 each independently represents -CH 2 -CH 2 -, -CH 2 -O-, -CH=CH-, -C≡C-, -COO- or a single bond, and n is 1 or 2.

10. The LC medium according to claim 1 or 2, characterized in that it additionally comprises one or more compounds of formula IV-16 wherein R 1 and R 2 each independently of the other represents a straight-chain alkyl group having from 1 to 6 C atoms.

11. The LC medium according to claim 1 or 2, characterized in that the polymerizable compound further comprises one or more compounds selected from the following formulae: wherein each group, each time it appears, is the same or different and each independently of one another has the following meanings: P 1 ,P 2 ,P 3 is an ethenyloxy group, acrylate group, methacrylate group, fluoroacrylate group, chloroacrylate group, oxetanyl group or epoxy group, Sp 1 ,Sp 2 ,Sp 3 is a single bond or a spacer group, wherein additionally, the group P 1 -Sp 1 -, P 1 -Sp 2 - and P 3 -Sp 3 - may also represent one or more of R aa , provided that at least one of the groups P 1 -Sp 1 -, P 2 -Sp 2 - and P 3 -Sp 3 - is different from R aa , R aa is H, F, Cl, CN or a straight-chain or branched alkyl group having 1 to 25 C atoms, where additionally, one or more non-adjacent CH 2 groups may 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-, and where additionally, one or more H atoms may be replaced by F, Cl, CN or P 1 -Sp 1 - R 0 ,R 00 is H or an alkyl group having 1 to 12 C atoms R y and R z is H, F, CH 3 or CF 3 , X 1 , X 2 , X 3 is -CO-O-, -O-CO- or a single bond Z 1 is -O-, -CO-, -C(R y R z )- or -CF 2 CF 2 -, Z 2 , Z 3 is -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 L is F, Cl, CN or a straight-chain or branched-chain, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 12 C atoms, L', L" are H, F or Cl, r is 0, 1, 2, 3 or 4, s is 0, 1, 2 or 3, t is 0, 1 or 2, x is 0 or 1.

12. The LC medium according to claim 1 or 2, characterized in that it additionally contains one or more additives selected from stabilizers, chiral dopants, polymerization initiators and self-aligning additives.

13. A method for preparing an LC medium according to any one of claims 1 to 12, comprising the following steps: mixing one or more polymerizable compounds as defined in any one of claims 1 and 11 to 12 with one or more compounds of the formulas IA, IB and IC as defined in any one of claims 1 to 10 and optionally one or more compounds of the formulas II, III, IV and / or V, and optionally mixing with further liquid crystal compounds and / or additives, and optionally polymerizing the polymerizable compounds.

14. An LC display comprising an LC medium as defined in any one of claims 1 - 12.

15. The LC display according to claim 14, which is a PSA or SA display.

16. The LC display according to claim 15, which is a PS-VA, PS-IPS, PS-FFS or SA-VA display.

17. The LC display according to claim 15 or 16, characterized in that it comprises two substrates, at least one of the substrates being transparent to light, an electrode provided on each substrate, or two electrodes provided on only one substrate, and a layer of an LC medium according to any one of claims 1 - 12 located between the substrates, wherein the polymerizable compounds are polymerized between the substrates of the display by UV light polymerization.

18. A method for preparing an LC display according to claim 17, comprising the steps of providing an LC medium according to any one of claims 1 to 12 between the substrates of the display and polymerizing the polymerizable compounds by irradiating with UV light.

19. A method for preparing an LC display according to claim 17, comprising the steps of providing an LC medium according to any one of claims 1 to 12 between the substrates of the display and polymerizing the polymerizable compounds by irradiating with UV light while applying a voltage to the electrodes of the display.

20. The method according to claim 18 or 19, characterized in that the wavelength range of the UV light is from 340 to 380 nm.

21. The method according to claim 18 or 19, characterized in that UV-LED lamps are used for irradiating with UV light.

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