Liquid crystalline media comprising polymerizable compounds

Abstract

The present invention relates to an LC medium (as a sub-class of liquid crystal material) comprising two or more polymerizable compounds, the use thereof for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of PSA (polymer stabilized alignment) or SA (self-alignment) mode, to LC displays of PSA or SA mode comprising such an LC medium, especially in LC displays of PSA (polymer stabilized alignment) or SA (self-alignment) mode. The invention also relates to a method for manufacturing the LC display by using the LC medium, in particular an energy-saving LC display and a method for producing the energy-saving LC display.

Description

Technical Field

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

[0002] The popularity 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, small tilt angles are generated in the LC molecules of the LC medium, which are 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 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 considered 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] It has also been proposed to use UV-LED lamps in the PSA method because they exhibit less power consumption, longer lifetime, and more efficient light energy transfer to the LC medium due to their narrower emission peaks, which allows for reducing the UV intensity and / or the 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.

[0007] Therefore, there is also a need for polymerizable LC media that enable the RM to polymerize effectively at longer UV wavelengths.

[0008] Another problem in the production of PSA displays is the presence or removal of residual amounts of unpolymerized RM, especially after the polymerization step used to generate the tilt angle in the display. For example, such unreacted RM may detrimentally affect the properties of the display by polymerizing in an uncontrolled manner, for example, during operation after the display is made.

[0009] Therefore, in PSA displays of the prior art, additional image retention is typically observed, which is caused by the presence of unpolymerized RM. The uncontrolled polymerization of the residual RM is initiated herein by UV light from the environment or by the backlight. In the switched display regions, after a plurality of addressing cycles, this changes the tilt angle. As a result, transmittance variations may occur in the switched regions, while remaining unchanged in the non-switched regions.

[0010] Therefore, it is desirable that the polymerization of the RM proceeds as completely as possible during the production of the PSA display and that the presence of unpolymerized RM in the display is excluded as much as possible or reduced to a minimum. Therefore, there is a need for RM and LC mixtures that enable or support highly efficient and complete polymerization of the RM. In addition, a controlled reaction of the residual RM amount is desirable. This would be simpler if the RM polymerizes faster and more efficiently than hitherto known materials.

[0011] Another problem observed in the operation of PSA displays is the stability of the tilt angle. Thus, it has been observed that the tilt angle (which is generated during the manufacturing process of displays by polymerizing RM as described above) does not remain constant but deteriorates after the display is subjected to voltage stress during its operation. This can have a negative impact on the display performance, for example, by increasing the transmittance in the black state and thus reducing the contrast ratio.

[0012] Accordingly, an object of the present invention is to provide an improved LC medium containing RM for PSA or SA displays, and PSA or SA display screens containing them, which exhibit very high specific resistance values, high VHR values, high reliability, low threshold voltages, short response times, high birefringence, good UV absorption (especially at longer UV wavelengths, preferably in the range of 340 to 380 nm), rapid and complete polymerization of RM, controlled generation of low tilt angles, high tilt angle stability after UV exposure, reduced image retention and ODF non-uniformity, and wherein the RM exhibits high solubility in the LC host mixture.

[0013] It has been found that one or more of these objects can be achieved by providing an LC medium containing two or more polymerizable compounds as disclosed and claimed hereinafter.

[0014] The present invention relates to an LC medium having negative dielectric anisotropy and containing one or more compounds selected from the formulas L1 and L2, and further containing two or more polymerizable compounds, preferably compounds of the formula M:

[0015]

[0016] R a -B 1 -(Z m -B 2 ) m -R b M

[0017] wherein each group is independent of one another and, each time it occurs, has the following meaning, the same or different:

[0018] R L1 is a straight-chain, branched-chain or cyclic alkyl group having 1 to 15 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CR 0 =CR 00 -, -C≡C-,

[0019]

[0020] Substituted in such a way that the O- and / or S-atoms are not directly connected to one another, and in which one or more H atoms are each optionally substituted by F or Cl, preferably an alkyl or alkoxy group having 1-6 C atoms

[0021] R L2 is a straight-chain alkenyl group having 2-6 carbon atoms, preferably selected from CH2=CH-, CH2=CHCH2-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- and CH3-CH=CH-(CH2)2-

[0022] X L is F, Cl, CF3 or CHF2, preferably F or CF3, very preferably CF3

[0023] Y L is H, F, Cl or CH3, preferably H

[0024] Y is H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, very preferably H

[0025] P is a polymerizable group

[0026] Sp is a spacer group or a single bond, which is optionally substituted by L a substituted

[0027] R a R b is P, P-Sp-, H, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, SF5 or a straight-chain or branched alkyl group having 1 to 25 C atoms, wherein furthermore one or more non-adjacent CH2 groups may each independently of one another be replaced by -C(R 0 )=C(R 00 )-, -C≡C-, -N(R 00 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O- and / or S-atoms are not directly connected to one another, and wherein furthermore one or more H atoms may also 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 may also represent a group spiro-linked to this saturated C atom

[0028] wherein the groups R a and R bat least one of them represents or contains the group P or P-Sp-,

[0029] P is a polymerizable group,

[0030] Sp is a spacer group or a single bond,

[0031] B 1 , B 2 represents an aromatic, heteroaromatic, alicyclic or heterocyclic group, which preferably has 4 to 25 ring atoms, the group may also contain fused rings, and the group is unsubstituted or mono- or polysubstituted by L,

[0032] Z m is -O-, -S-, -CO-, -CO-O-, -OCO-, -O-CO-O-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -(CH2) n1 -, -CF2CH2-, -CH2CF2-, -(CF2) n1 -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, -CH2CH2-CO-O-, O-CO-CH2-CH2-, -CR 0 R 00 - or a single bond,

[0033] R 0 , R 00 is H or an alkyl group having 1 to 12 C atoms,

[0034] m is 0, 1, 2, 3 or 4,

[0035] n1 is 1, 2, 3 or 4,

[0036] L is P, P-Sp-, OH, CH2OH, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x )2, -C(=O)Y 1 , -C(=O)R x , -N(R x )2, an optionally substituted silyl group, an optionally substituted aryl group having 6 to 20 C atoms or a straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 25 C atoms, wherein one or more H atoms may additionally be replaced by F, Cl, P or P-Sp-,

[0037] Y 1is a halogen,

[0038] R x is P, P-Sp-, H, a halogen, a linear, branched or cyclic alkyl group having 1 to 25 C atoms, wherein one or more non-adjacent CH2 groups may additionally be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly linked to one another, and wherein one or more H atoms may additionally 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.

[0039] The invention further relates to an LC medium as described above and below, which additionally contains one or more additives selected from stabilizers, chiral dopants, polymerization initiators and self-aligning additives.

[0040] The invention further relates to the use of an LC medium as described above and below in an LC display in PSA or SA mode.

[0041] The invention further relates to a method for preparing an LC medium as described above and below, comprising the steps of mixing one or more polymerizable compounds of formula M with one or more compounds of formula L1 and / or L2, and optionally mixing with further LC compounds and / or additives.

[0042] The invention further relates to an LC display as described above and below, comprising an LC medium according to the invention, which is a PSA or SA display, preferably a PS-VA, PS-IPS, PS-FFS, PS-UB-FFS or SA-VA display.

[0043] The invention further relates to an LC display as described above and below, comprising an LC medium, 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, PS-UB-FFS or SA-VA display.

[0044] 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 one substrate, and a layer of an LC medium as described above and below located between the substrates, wherein the polymerizable compound is polymerized between the substrates of the display by UV light polymerization.

[0045] The present invention also relates to a method of manufacturing an LC display as described in the context, comprising the steps of filling or otherwise providing an LC medium as described in the context between the substrates of the display, and polymerizing a polymerizable compound, preferably by UV light irradiation, said UV light preferably having a wavelength of > 340 nm, preferably > 360 nm, preferably in the range of 340 - 400 nm, more preferably in the range of 350 - 390 nm, very preferably in the range of 360 to 380 nm, most preferably in the range of 360 - 368 nm, and preferably applying a voltage to the electrodes of the display simultaneously.

[0046] The present invention further relates to a method of manufacturing an LC display as described in the context, wherein the irradiation of the polymerizable compound is carried out using a UV-LED lamp.

[0047] When used in PSA displays, the LC media of the present invention exhibit the following advantageous properties:

[0048] - Appropriate tilt generation within a certain process window,

[0049] - Fast polymerization, minimizing the RM residue after UV treatment,

[0050] - High voltage holding ratio after UV treatment,

[0051] - Good tilt stability,

[0052] - Good VHR,

[0053] - Sufficient thermal stability,

[0054] - Sufficient solubility in organic solvents typically used in display manufacturing.

[0055] Additionally, the LC media of the present invention exhibit one or more of the following advantageous properties:

[0056] - They generate a tilt angle of the desired angle after exposure to UV,

[0057] - They provide high tilt stability,

[0058] - They exhibit good UV absorption, especially at longer UV wavelengths, preferably in the range of 340 - 400 nm, more preferably in the range of 350 - 390 nm, very preferably in the range of 360 to 380 nm, most preferably in the range of 360 - 368 nm, and can polymerize RM quickly and completely at these wavelengths,

[0059] - They are suitable for PSA displays prepared by a polymerization process using UV-LED lamps,

[0060] - They are capable of controlling the time range of the first UV step that generates the tilt angle during the UV treatment process.

[0061] - They minimize the time range of the second UV step as much as possible to minimize production costs.

[0062] - After the first and second UV exposure steps, they reduce or avoid any negative impact of the residual RM on the performance parameters of the LC mixture, such as VHR, tilt stability, etc.

[0063] As described below, the alkenyl groups in the compounds of Formula 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.

[0064] Unless otherwise specified, the polymerizable compounds and the compounds of Formula II are preferably selected from achiral compounds.

[0065] 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.

[0066] As used herein, the term "full width at half maximum" or "FWHM" represents the width of the spectral curve measured between those points on the y-axis that are half of the maximum amplitude.

[0067] 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" for a bandpass filter, for example, means a wavelength within (outside) a given range λ, and for a cut-off filter, means a wavelength above (below) a given λ value.

[0068] As used herein, the terms "active layer" and "switchable layer" denote 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 upon application of 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.

[0069] As used herein, the terms "tilt" and "tilt angle" are to be understood as denoting a tilted alignment of the LC molecules of the LC medium with respect to the cell surfaces in an LC display (preferably a PSA display herein), and are to be understood as including "pretilt" and "pretilt angle". The tilt angle herein denotes the average angle (<90°) between the longitudinal molecular axis (LC director) of the LC molecules and the surface of the planar outer plates forming the LC cell. A low absolute value of the 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 relate to such a measurement method.

[0070] As used herein, the terms "reactive mesogen" and "RM" are to be understood as denoting a compound containing a mesogenic or liquid crystalline backbone, and one or more polymerizable functional groups attached thereto, and said functional groups are also referred to as "polymerizable groups" or "P".

[0071] Unless otherwise stated, the term "polymerizable compound" as used herein is to be understood as denoting a polymerizable monomer compound.

[0072] The SA-VA displays of the present invention will be in the polymer-stabilized mode since they contain an LC medium containing RMs of formula I and II or are manufactured by using an LC medium containing RMs of formula I and II. Thus, as used herein, even if not explicitly mentioned, the term "SA-VA display" in relation to the displays of the present invention is to be understood as referring to a polymer-stabilized SA-VA display.

[0073] As used herein, the term "low molecular weight compound" is to be understood as denoting monomers and / or compounds not prepared by a polymerization reaction, as opposed to "polymeric compounds" or "polymers".

[0074] As used herein, the term "non-polymerizable compound" will be understood as denoting a compound which does not contain functional groups suitable for polymerization under the conditions normally applied to the polymerization of RMs.

[0075] As used herein, the term "mesogenic group" is known to those skilled in the art and has been described in the literature, and it refers to a group that substantially contributes to the generation of a liquid crystal (LC) phase in a low molecular weight or polymeric substance 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 being mixed 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.

[0076] 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 has been 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.

[0077] In the context, represents a trans-1,4-cyclohexylene ring, and represents a 1,4-phenylene ring.

[0078] In the group the single bond between the two ring atoms can be connected to any free position of the benzene ring.

[0079] If in the formulas shown above and below, such as R 1A,2A 、R 1 、R 2 、R 11,12,13 、R 21,22 、R 31,32 、R 41,42 、R 51 ,52 、R 61,62 、R 71,72 、R 81,82,83 、R Q 、R 0 、R、R M 、R S 、R S1,S2,S3,S4If the end group of L represents an alkyl group and / or an alkoxy group, it may be straight-chain or branched. It is preferably straight-chain and has 2, 3, 4, 5, 6 or 7 C atoms and thus preferably represents ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy, and also methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy or tetradecyloxy.

[0080] If one of the above-mentioned end groups represents an alkyl group in which one or more CH2 groups are replaced by S, it may be straight-chain or branched. It is preferably straight-chain and has 1, 2, 3, 4, 5, 6 or 7 C atoms and thus preferably represents thiomethyl, thioethyl, thiopropyl, thiobutyl, thiopentyl, thiohexyl or thioheptyl.

[0081] 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.

[0082] If one of the above-mentioned end groups represents an alkoxy or oxaalkyl group, it may also contain one or more additional oxygen atoms, provided that the oxygen atoms are not directly linked to each other.

[0083] If one of the above-mentioned end groups represents an alkyl group in which one CH2 group has been replaced by -CH=CH-, it may be straight-chain or branched. It is preferably straight-chain and has 2 to 10 C atoms. Thus, it particularly represents vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-enyl, oct-1-, -2-, -3-, -4-, -5-, -6- or -7-enyl, non-1-, -2-, -3-, -4-, -5-, -6-, -7- or -8-enyl, dec-1-, -2-, -3-, -4-, -5-, -6-, -7-, -8- or -9-enyl.

[0084] If one of the terminal groups mentioned above represents an alkyl or alkenyl group that is at least monosubstituted by a halogen, the group is preferably straight-chain and the halogen is preferably F or Cl. In the case of polysubstitution, the halogen is preferably F. The resulting group also includes perfluorinated groups. In the case of monosubstitution, the fluorine or chlorine substituent can be in any desired position, but is preferably in the ω-position.

[0085] In another preferred embodiment, one or more of the above terminal groups, such as R 1A,2A 、R 1 、R 2 、R 11 ,12,13 、R 31,32 、R 41,42 、R 51,52 、R 61,62 、R 71,72 、R 81,82,83 、R Q 、R 0 、R、R M 、R S 、R S1,S2,S3,S4 or L, are selected from the following:

[0086]

[0087] -S 1 -F, -O-S 1 -F, -O-S1-O-S2, where S 1 is C 1-12 -alkylene or C 2-12 -alkenylene and S 2 is H, C 1-12 -alkyl or C 2-12 -alkenyl, and is very preferably selected from the following:

[0088] -OCH2OCH3, -O(CH2)3OCH3, -O(CH2)4OCH3, -O(CH2)2F, -O(CH2)3F, -O(CH2)4F.

[0089] The halogen is preferably F or Cl, very preferably F.

[0090] The group -CR 0 =CR 00 - is preferably -CH=CH-.

[0091] -CO-, -C(=O)- and -C(O)- represent a carbonyl group, i.e.

[0092] Preferred substituent L is, for example, F, Cl, Br, I, -CN, -NO2, -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 alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group each having 1 - 25 C atoms, where one or more H atoms may optionally be replaced by F or Cl, an optionally substituted silyl group having 1 - 20 Si atoms, or an optionally substituted aryl group having 6 - 25, preferably 6 - 15 C atoms,

[0093] where R x represents H, F, Cl, CN, or a straight-chain, branched or cyclic alkyl group having 1 - 25 C atoms, where one or more non-adjacent CH2 - groups are optionally replaced, in a manner such that O - and / or S - atoms are not directly connected to each other, by -O-, -S-, -CO-, -CO - O-, -O - CO-, -O - CO - O-, and where one or more H atoms are each optionally replaced by F, Cl, P - or P - Sp, and

[0094] Y 1 represents a halogen.

[0095] Particularly preferred substituents L are, for example, F, Cl, CN, NO2, CH3, C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5, and phenyl.

[0096] Preferably

[0097] where L has one of the meanings indicated above.

[0098] In the compounds of formula L1 and its sub-formulas, R L1 preferably represents an alkyl group having 1, 2, 3, 4, 5 or 6 C atoms, where the CH2 group is optionally replaced by cyclopropane - 1,2 - diyl or cyclopentane - 1,2 - diyl, very preferably propyl, pentyl, cyclopropyl, cyclopentyl, cyclopropylmethyl or cyclopentylmethyl, most preferably propyl or pentyl.

[0099] In the compounds of formula L1 and its sub-formulas, X L preferably represents F or CF3, very preferably CF3.

[0100] In the compounds of formula L1 and its sub-formulas, Y LPreferably represents H or F, very preferably H.

[0101] In the compound of formula L1, Y preferably represents H or CH3, very preferably H.

[0102] Preferred compounds of formula L1 are selected from the following sub-formulas:

[0103]

[0104]

[0105] wherein R L1 has the meaning given in formula L1 above, preferably represents an alkyl group having 1 to 6 C atoms, wherein the CH2 group is optionally replaced by cyclopropane-1,2-diyl or cyclopentane-1,2-diyl, very preferably propyl, pentyl, cyclopropyl, cyclopentyl, cyclopropylmethyl or cyclopentylmethyl, most preferably propyl or pentyl.

[0106] Very preferably the compound of formula L1-2, especially wherein R L1 is n-propyl or n-pentyl.

[0107] In the compounds of formula L2 and its sub-formulas, R L1 preferably represents an alkyl group having 1, 2, 3, 4, 5 or 6 C atoms, very preferably methyl.

[0108] In the compounds of formula L2 and its sub-formulas, R L2 is preferably selected from CH2=CH-, CH2=CHCH2-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- and CH3-CH=CH-(CH2)2-, more preferably selected from CH2=CH-, CH2=CHCH2- and CH3-CH=CH-, very preferably selected from CH2=CH-.

[0109] In the compounds of formula L2 and its sub-formulas, Y L preferably represents H or F, very preferably H.

[0110] In the compounds of formula L2 and its sub-formulas, Y preferably represents H or CH3, very preferably H.

[0111] Preferred compounds of formula L2 are selected from the following sub-formulas:

[0112]

[0113] "alkyl" means a straight-chain alkyl group having 1 to 6 C atoms, wherein the CH2 group may be replaced by cyclopropane-1,2-diyl or cyclopentane-1,2-dialkyl, preferably represents methyl, ethyl or propyl.

[0114] Compound of formula L2-1 is highly preferred, especially where R L1 is methyl.

[0115] Preferably, the total proportion of the compound of formula L1 or its sub-formula in the LC medium is 0.1 to 10% by weight, very preferably 0.2 to 5% by weight, and most preferably 0.3 to 3% by weight.

[0116] Preferably, the total proportion of the compound of formula L2 or its sub-formula in the LC medium is 0.1 to 10% by weight, very preferably 0.2 to 5% by weight, and most preferably 0.3 to 3% by weight.

[0117] The following lists further preferred embodiments of the LC medium according to the present invention, including any combination thereof:

[0118] Preferably, the LC medium further comprises one or more compounds of formula II,

[0119]

[0120] wherein each group independently of one another and each occurrence is the same or different and has the following meanings

[0121] R 21 and R 22 are H, a straight-chain, branched-chain or cyclic alkyl or alkoxy group having 1-20 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CR 0 =CR 00 -, -C≡C-,

[0122]

[0123] such that the 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, CN or CF3, preferably an alkyl or alkoxy group having 1-6 C atoms,

[0124] R 0 ,R 00 are H or an alkyl group having 1-12 C atoms,

[0125] A 1 and A 2 are groups selected from the following formula

[0126]

[0127] are preferably selected from formulae A1, A2, A3, A4, A5, A6, A9 and A10, very preferably selected from formulae A1, A2, A3, A4, A5, A9 and A10,

[0128] Z 1 and Z 2 are -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, preferably a single bond,

[0129] L 1 , L 2 , L 3 and L 4 are F, Cl, OCF3, CF3, CH3, CH2F or CHF2, preferably F or Cl, very preferably F,

[0130] Y is H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, very preferably H,

[0131] L C is CH3 or OCH3, preferably CH3,

[0132] a1 is 0, 1 or 2,

[0133] a2 is 0 or 1.

[0134] Preferably, the LC medium comprises a compound of formula II selected from one or more of the compounds of formulae IIA, IIB, IIC and IID,

[0135]

[0136] wherein each group is the same or different at each occurrence and each independently of one another has the following meanings:

[0137] R 21 , R 22 is H, an alkyl, alkoxy or alkenyl group having at most 15 (preferably at most 6) C atoms, which is unsubstituted or mono-substituted by F, Cl, CN or CF3, and wherein furthermore one or more CH2 groups in these groups may be replaced by -O-, -S-, -C≡C-, -CF2O-, -OCF2-, -OC-O-, -O-CO- in such a way that O- and / or S-atoms are not directly linked to one another

[0138]

[0139] alternatively,

[0140] L 1 to L 4 is F, Cl, CF3 or CHF2,

[0141] Y is H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, particularly preferably H,

[0142] Z 1 , Z 2 is a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CH=CHCH2O,

[0143] p is 0, 1 or 2, or

[0144] q is 0 or 1.

[0145] Preferred compounds of formulae IIA, IIB, IIC and IID are those in which R 22 represents an alkyl or alkoxy group having at most 15 C atoms and very preferably represents (O)C v H 2v+1 where (O) is an oxygen atom or a single bond and v is 1, 2, 3, 4, 5 or 6.

[0146] Further preferred compounds of formulae IIA, IIB, IIC and IID are those in which R 21 or R 22 represents or contains a cycloalkyl or cycloalkoxy group, preferably selected from

[0147]

[0148] 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

[0149]

[0150] Further preferred compounds of formulae IIA, IIB, IIC and IID are indicated below.

[0151] In a preferred embodiment, the LC medium comprises one or more compounds of formula IIA selected from the following formulae:

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162]

[0163]

[0164] wherein the exponent a represents 1 or 2, alkyl and alkyl * each independently of one another represent straight-chain alkyls having 1 to 6 C atoms, alkenyl represents a straight-chain alkenyl having 2 to 6 C atoms, and (O) represents an oxygen atom or a single bond, and alkenyl preferably represents CH2═CH—, CH2═CHCH2CH2—, CH3—CH═CH—, CH3—CH2—CH═CH—, CH3—(CH2)2—CH═CH—, CH3—(CH2)3—CH═CH— or CH3—CH═CH—(CH2)2—.

[0165] Particularly preferred LC media according to the invention comprise one or more compounds selected from the group consisting of formulae IIA-2, IIA-8, IIA-10, IIA-16, II-18, IIA-40, IIA-41, IIA-42 and IA-43.

[0166] In another preferred embodiment, the LC medium comprises one or more compounds of formula IIB selected from the group consisting of formulae IIB-1 to IIB-26,

[0167]

[0168]

[0169]

[0170]

[0171] wherein alkyl and alkyl* each independently of the other represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl represents a straight-chain alkenyl group having 2 to 6 C atoms, and (O) represents an oxygen atom or a single bond, and alkenyl preferably represents CH2═CH—, CH2═CHCH2CH2—, CH3—CH═CH—, CH3—CH2—CH═CH—, CH3—(CH2)2—CH═CH—, CH3—(CH2)3—CH═CH— or CH3—CH═CH—(CH2)2—.

[0172] Particularly preferred LC media according to the invention comprise one or more compounds selected from those of formulae IIB-2, IIB-10 and IIB-16.

[0173] In another preferred embodiment, the LC medium comprises one or more compounds of formula IIC selected from those of formula IIC-1,

[0174]

[0175] wherein alkyl and alkyl* each independently of the other represent a straight-chain alkyl group having 1 to 6 C atoms, preferably in an amount of from 0.5 wt% to 5 wt%, in particular from 1 wt% to 3 wt%.

[0176] In another preferred embodiment, the LC medium comprises one or more compounds of formula IID selected from the following formulae

[0177]

[0178]

[0179]

[0180]

[0181]

[0182] wherein alkyl and alkyl* each independently of the other represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl represents a straight-chain alkenyl group having 2 to 6 C atoms, (O) represents an oxygen atom or a single bond, Y represents H or CH3, and alkenyl preferably represents CH2═CH—, CH2═CHCH2CH2—, CH3—CH═CH—, CH3—CH2—CH═CH—, CH3—(CH2)2—CH═CH—, CH3—(CH2)3—CH═CH— or CH3—CH═CH—(CH2)2—.

[0183] According to a further preferred embodiment of the invention, the LC medium comprises one or more compounds of formula IID-1 and / or IID-4.

[0184] According to a further preferred embodiment of the invention, the LC medium comprises one or more compounds of formula IID, where q is 0, Y is H, R 22 represents an alkyl or alkoxy group having 1 to 6 C atoms, where one CH2 group is optionally replaced by cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl, preferably selected from the group consisting of formulae IID-1, IID-15, IID-17, IID-18, IID-19, IID-20, IID-21, IID-22 and IID-23, very preferably selected from the group consisting of formulae IID-1, IID-21, IID-22 and IID-23.

[0185] Very preferably, the compounds of formula IID are compounds selected from the following sub-formulae,

[0186]

[0187]

[0188]

[0189]

[0190]

[0191]

[0192] where v is 1, 2, 3, 4, 5 or 6.

[0193] In a preferred embodiment, the LC medium comprises one or more compounds of formula IID-10a

[0194]

[0195] where R 21 , Y and q have the meanings given in formula IID, and R 23 is

[0196] , where r is 0, 1, 2, 3, 4, 5 or 6 and s

[0197] is 1, 2 or 3.

[0198] Preferred compounds of formula IID-10a are selected from the following sub-formulae:

[0199]

[0200]

[0201]

[0202]

[0203]

[0204] Particularly preferred LC media according to the invention comprise one or more compounds selected from 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 and IID-10 or sub-formulae thereof.

[0205] The proportion of the compound of formula IIA and / or IIB in the overall mixture is preferably at least 20 wt%.

[0206] Preferably, the LC medium comprises one or more compounds of formula IIA-2 selected from the following sub-formulae:

[0207]

[0208]

[0209] Alternatively, preferably in addition to the compounds of formulae IIA-2-1 to IIA-2-5, the LC medium further comprises one or more compounds of the following formulae:

[0210]

[0211]

[0212] More preferably, the LC medium comprises one or more compounds of formula IIA-10 selected from the following sub-formulae:

[0213]

[0214] Alternatively, preferably in addition to the compounds of formulae IIA-10-1 to IIA-10-5, the LC medium further comprises one or more compounds of the following formulae:

[0215]

[0216] Preferably, the LC medium comprises one or more compounds of formula IIB-10 selected from the following sub-formulae:

[0217]

[0218]

[0219] Alternatively, preferably in addition to the compounds of formulas IIB-10-1 to IIB-10-5, the LC medium further comprises one or more compounds of the following formula:

[0220]

[0221]

[0222] In another preferred embodiment, the LC medium comprises one or more compounds of formula III,

[0223]

[0224] wherein

[0225] R 31 and R 32 each independently of one another represent H, an alkyl, alkoxy or alkenyl group having at most 15 C atoms, which is unsubstituted, monosubstituted by F, Cl, CN or CF3 or at least monosubstituted by halogen, wherein furthermore one or more CH2 groups in these groups may be replaced by -O-, -S-,

[0226]

[0227] -C≡C-, -CF2O-, -OCF2-, -OC-O- or -O-CO- such that the O atoms are not directly linked to one another,

[0228] Y 1 and Y 2 is H, F, Cl, CF3, CHF2, CH3 or OCH3, preferably H, CH3 or OCH3, very preferably H,

[0229] A 3 each occurrence independently of one another represents

[0230] a) 1,4-cyclohexenyl or 1,4-cyclohexyl, wherein one or two non-adjacent CH2 groups may be replaced by -O- or -S-,

[0231] b) 1,4-phenylene, wherein one or two CH groups may be replaced by N, or

[0232] 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,

[0233] wherein the groups a), b) and c) may be mono- or polysubstituted by halogen atoms,

[0234] n represents 0, 1 or 2, preferably 0 or 1,

[0235] Z 1 each occurrence independently of one another represents -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-CH2O-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond, and

[0236] L 11 and L 12 each independently of one another represents F, Cl, CF3 or CHF2, preferably H or F, most preferably F, and

[0237] W represents O or S.

[0238] In the compound of formula III, R 31 and R 32 are preferably selected from straight-chain alkyl or alkoxy groups having 1-12, preferably 1-7 C atoms, straight-chain alkenyl groups having 2-12, preferably 2-7 C atoms, and cyclic alkyl or alkoxy groups having 3-12, preferably 3-8 C atoms.

[0239] In a preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III selected from formulae III-1 and III-2,

[0240]

[0241] wherein the groups occurring have the same meanings as given above under formula III, and preferably

[0242] R 31 and R 32 each independently of one another is an alkyl, alkenyl or alkoxy group having at most 15 C atoms, more preferably one or both of them represent an alkoxy group, and

[0243] L 11 and L 12 each preferably represents F.

[0244] In another preferred embodiment, the LC medium comprises one or more compounds of formula III-1 selected from formulae III-1-1 to III-1-10, preferably formula III-1-6,

[0245]

[0246]

[0247] wherein alkyl and alkyl * each independently represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl and alkenyl * each independently represent a straight-chain alkenyl group having 2 to 6 C atoms, alkoxy and alkoxy * each independently represent a straight-chain alkoxy group having 1 to 6 C atoms, and L 11 and L 12 each independently represent F or Cl, preferably both are F.

[0248] In another preferred embodiment, the LC medium comprises one or more compounds of formula III-2, which are selected from the compounds of sub-formulas III-2-1 to III-2-10, preferably the compound of sub-formula III-2-1,

[0249]

[0250]

[0251] wherein alkyl and alkyl * each independently represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl and alkenyl * each independently represent a straight-chain alkenyl group having 2 to 6 C atoms, alkoxy and alkoxy * each independently represent a straight-chain alkoxy group having 1 to 6 C atoms, and L 11 and L 12 each independently represent F or Cl, preferably both are F.

[0252] Highly preferred compounds of formula III-2 are selected from the following sub-formulas,

[0253]

[0254]

[0255] wherein alkoxy represents a straight-chain alkoxy group having 1 to 6 C atoms, preferably ethoxy, propoxy, butoxy or pentyloxy, very preferably ethoxy or propoxy.

[0256] Highly preferred are the compounds of formula III-2-1-3, III-2-1-4 and III-2-1-5.

[0257] In another preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III selected from formulae III-3-1 and III-3-2

[0258]

[0259] wherein L 11 and L 12 have the same meanings as given under formula III, (O) represents O or a single bond,

[0260] R 33 represents an alkyl or alkenyl group having at most 7 C atoms, or the group Cy-C m H 2m+1 -,

[0261] 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

[0262] 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.

[0263] The compounds of formula III-3-1 and / or III-3-2 can replace the compounds of formula III-1 and / or III-2 or be additionally contained in the LC medium, preferably additionally.

[0264] Very preferred compounds of formula III-3-1 are as follows,

[0265]

[0266]

[0267] wherein alkoxy represents a straight-chain alkoxy group having 1-6 C atoms.

[0268] Very preferred compounds of formula III-3-2 are as follows,

[0269]

[0270] wherein alkoxy represents a straight-chain alkoxy group having 1-6 C atoms, preferably ethoxy, propoxy, butoxy or pentyloxy, very preferably ethoxy or propoxy.

[0271] In another preferred embodiment of the present invention, the LC medium comprises one or more compounds of formulae III-4 to III-6, preferably a compound of formula III-5,

[0272]

[0273]

[0274] 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 - 7 C atoms.

[0275] In another preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III, which are selected from compounds of sub-formulas III-7 to III-9, preferably the compound of sub-formula III-8,

[0276]

[0277] 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 - 7 C atoms.

[0278] In another preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III, which are selected from sub-formula III-10,

[0279]

[0280] wherein R 31 and R 32 have the meanings given above.

[0281] Very preferably, the compound of formula III-10 is selected from the following formula,

[0282]

[0283]

[0284] wherein R 32 represents an alkyl group having 1 to 7 C atoms, preferably ethyl, n-propyl or n-butyl, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl, or alternatively -(CH2) n F, where n is 2, 3, 4 or 5, preferably C2H4F.

[0285] In another preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula III, which are selected from sub-formula III-11,

[0286]

[0287] wherein R 31 and R 32 have the meanings given above.

[0288] The highly preferred compounds of formula III-11 are selected from the following formulas,

[0289]

[0290]

[0291]

[0292] wherein R 32 represents an alkyl group having 1 to 7 carbon atoms, preferably ethyl, n-propyl or n-butyl, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl, or alternatively -(CH2) n F, where n is 2, 3, 4 or 5, preferably C2H4F.

[0293] In a preferred embodiment, the LC medium comprises one or more compounds of formula IV,

[0294]

[0295] wherein

[0296] R 41 represents an unsubstituted alkyl group having 1-7 carbon atoms, wherein in addition, one or more CH2 groups may be substituted, or an unsubstituted alkenyl group having 2-7 carbon atoms, preferably a normal alkyl group, particularly preferably having 2, 3, 4 or 5 carbon atoms, and

[0297] R 42 represents an unsubstituted alkyl group having 1-7 carbon atoms, or an unsubstituted alkoxy group having 1-6 carbon atoms (both preferably having 2-5 carbon atoms), an unsubstituted alkenyl group having 2-7 carbon atoms, preferably having 2, 3 or 4 carbon atoms, more preferably vinyl or 1-propenyl and especially vinyl.

[0298] The compounds of formula IV are preferably selected from the compounds of formula IV-1 to IV-4,

[0299]

[0300]

[0301] wherein

[0302] alkyl and alkyl’ independently of each other represent an alkyl group having 1-7 carbon atoms, preferably having 2-5 carbon atoms,

[0303] alkenyl represents an alkenyl group having 2-5 carbon atoms, preferably having 2-4 carbon atoms, particularly preferably 2 carbon atoms,

[0304] "alkenyl" means an alkenyl group having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms, and

[0305] "alkoxy" means an alkoxy group having 1 to 5 C atoms, preferably having 2 to 4 C atoms.

[0306] Preferably, the LC medium comprises one or more compounds selected from the compounds of formulae IV-1-1 to IV-1-6:

[0307]

[0308] Very preferably, the LC medium according to the invention comprises one or more compounds of formula IV-2-1 and / or IV-2-2

[0309]

[0310] Very preferably, the LC medium according to the invention comprises a compound of formula IV-3, in particular a compound selected from the following sub-formulae:

[0311]

[0312]

[0313] In another preferred embodiment, the LC medium according to the invention comprises a compound of formula IV-3 which is one or more compounds selected from the following sub-formulae:

[0314]

[0315]

[0316]

[0317] wherein alkyl represents methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or n-pentyl.

[0318] Very preferably, the LC medium according to the invention comprises a compound of formula IV-4, in particular a compound selected from the following formulae:

[0319]

[0320] In another preferred embodiment, the LC medium comprises one or more compounds of formula IV-4 and its sub-formulae, wherein

[0321] "alkenyl" and "alkenyl'" wherein

[0322] one or both of

[0323] m is 0, 1 or 2, and n is 0, 1 or 2, and very preferably a compound selected from formulas IV-4-3 to IV-4-6.

[0324] Very preferably, the LC medium according to the invention comprises one or more compounds of formula IV-1 or its sub-formulas and / or one or more compounds of formula IV-3 or its sub-formulas and / or one or more compounds of formula IV-4 or its sub-formulas, wherein the total concentration of these compounds of formula IV-1 is in the range of 1% to 30%.

[0325] The LC medium according to the invention preferably additionally comprises one or more compounds of formula IVa,

[0326]

[0327] wherein

[0328] R 41 and R 42 each independently of one another represents a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkoxy having at most 12 C atoms,

[0329] represents

[0330]

[0331] Z 4 represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -C4H8- or -CF=CF-.

[0332] Preferred compounds of formula IVa are indicated as follows:

[0333]

[0334] wherein alkyl and alkyl* each independently of one another represent a straight-chain alkyl having 1-6 C atoms.

[0335] The LC medium according to the invention preferably comprises at least one compound of formula IVa-1 and / or formula IVa-2.

[0336] The proportion of the compound of formula IVa in the overall mixture is preferably at least 5 wt%.

[0337] Preferably, the LC medium comprises one or more compounds of formulas IVb-1 to IVb-3

[0338]

[0339] wherein

[0340] alkyl and alkyl* each independently of the other represent a straight-chain alkyl group having 1 to 6 C atoms, and

[0341] alkenyl and alkenyl* each independently of the other represent a straight-chain alkenyl group having 2 to 6 C atoms.

[0342] The proportion of the compounds of formulae IV-1 to IV-3 in the overall mixture is preferably at least 3 wt%, in particular ≥ 5 wt%.

[0343] Among the compounds of formulae IVb-1 to IVb-3, the compound of formula IVb-2 is particularly preferred.

[0344] Particularly preferred compounds of formulae IV-1 to IV-3 are selected from the following formulae

[0345]

[0346]

[0347] wherein alkyl* represents an alkyl group having 1 to 6 C atoms, preferably n-propyl.

[0348] The LC medium according to the invention particularly preferably comprises one or more compounds of formulae IVb-1-1 and / or IVb-2-3.

[0349] In another preferred embodiment, the LC medium according to the invention comprises one or more compounds of formula V

[0350]

[0351] wherein

[0352] R 51 and R 52 each independently of the other represent H, an alkyl, alkoxy or alkenyl group having at most 15 C atoms, which is unsubstituted, monosubstituted by F, Cl, CN or CF3 or at least monosubstituted by halogen, where in addition one or more CH2 groups in these groups may be replaced by -O-, -S-, -C≡C-, -CF2O-, -OCF2-, -OC-O-, -O-CO- in such a way that the O atoms are not directly linked to each other,

[0353]

[0354] alternatively, and preferably represents an alkyl group having 1 - 7 C atoms, preferably a normal alkyl group, particularly preferably a normal alkyl group having 1 - 5 C atoms, an alkoxy group having 1 - 6 C atoms, preferably a normal alkoxy group, particularly preferably a normal alkoxy group having 2 - 5 C atoms, an alkoxyalkyl, alkenyl or alkenyloxy group having 2 - 7 C atoms, preferably an alkenyloxy group,

[0355] identically or differently, represents

[0356]

[0357]

[0358] wherein

[0359] preferably represents

[0360] Z 51 , Z 52 each independently of one another represents -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, preferably -CH2-CH2-, -CH2-O- or a single bond, and particularly preferably a single bond, and

[0361] n is 1 or 2.

[0362] The compound of formula V is preferably selected from the compounds of formula V-1 to V-17:

[0363]

[0364]

[0365] wherein R 1 and R 2 have the meanings indicated above for R 51 and R 52 .

[0366] R 1 and R 2 preferably each independently of one another represent a straight-chain alkyl or alkenyl group.

[0367] The preferred LC medium comprises one or more compounds of formula V-1, V-3, V-4, V-6, V-7, V-10, V-11, V-12, V-14, V-15 and / or V-16.

[0368] The LC medium according to the invention very particularly preferably comprises a compound of formula V-10 and / or IV-1, in particular in an amount of 5 - 30%.

[0369] Preferred compounds of formula V-10 are indicated below:

[0370]

[0371] The LC medium according to the invention very particularly preferably comprises a combination of a tricyclic compound of formula V-10a and / or V-10b with one or more bicyclic compounds of formula IV-1. The total proportion of the compound of formula V-10a and / or V-10b in combination with one or more compounds selected from the bicyclohexyl compounds of formula IV-1 is from 5 to 40%, very particularly preferably from 15 to 35%.

[0372] A particularly preferred LC medium comprises the compound V-10a and / or IV-1-1

[0373]

[0374] Based on the overall mixture, the compounds V-10a and IV-1-1 are preferably present in the mixture in a concentration of from 5 to 30%, very preferably from 10 to 25%.

[0375] A preferred LC medium comprises at least one compound selected from the following compounds

[0376]

[0377] wherein R 1 ,R 2 ,R 41 and R 42 have the meanings indicated above. Preferably in the compounds V-6, V-7 and IV, R 1 and R 41 each represent an alkyl or alkenyl group having 1 to 6 or 2 to 6 carbon atoms respectively, and R 2 and R 42 represent an alkenyl group having 2 to 6 carbon atoms. Preferably in the compound V-14, R 1 represents an alkyl or alkenyl group having 1 to 6 or 2 to 6 carbon atoms, and R 2 represents an alkyl group having 1 to 6 carbon atoms.

[0378] In another preferred embodiment, the LC medium according to the invention comprises one or more compounds of formula V-7, preferably selected from the compounds of formula V-7a to V-7e:

[0379]

[0380] wherein alkyl represents an alkyl group having 1 - 7 C atoms, alkenyl represents an alkenyl group having 2 - 7 C atoms, and cycloalkyl represents a cycloalkyl group having 3 - 12 C atoms, preferably cyclopropyl, cyclobutyl, cyclopentyl, cyclopropylalkyl, cyclobutylalkyl or cyclopentylalkyl.

[0381] The compounds of formulae V - 7a to V - 7e which are very preferably selected from the compounds of the following sub - formulae:

[0382]

[0383]

[0384]

[0385]

[0386] wherein alkyl represents ethyl, n - propyl, n - butyl or n - pentyl, preferably n - propyl.

[0387] Further preferred are the compounds of formula V, wherein R 51 and R 52 each independently represent a straight - chain alkyl group having 1 - 7 C atoms or an alkenyl group having 2 - 7 C atoms.

[0388] In a preferred embodiment of the present invention, the LC medium additionally comprises one or more compounds of formulae VI - 1 to VI - 25,

[0389]

[0390]

[0391]

[0392] wherein

[0393] 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, OCF3 or OCHF2, 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.

[0394] R preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy.

[0395] X preferably represents F or OCH3, very preferably F.

[0396] The LC media according to the invention preferably comprise the terphenyls of the formulae VI-1 to VI-25 in an amount of 2 to 30% by weight, in particular 5 to 20% by weight.

[0397] Particularly preferred are compounds of formulae VI-1, VI-2, VI-4, VI-20, VI-21 and VI-22, in which X represents F. In these compounds, R preferably represents alkyl and alkoxy, each having 1 to 5 C atoms. In the compound of formula VI-20, R preferably represents alkyl or alkenyl, in particular alkyl. In the compound of formula VI-21, R preferably represents alkyl. In the compounds of formulae VI-22 to VI-25, X preferably represents F.

[0398] Terphenyls of the formulae VI-1 to VI-25 are preferably used in the LC media according to the invention if the Δn value of the mixture is ≥ 0.1. Preferred LC media comprise 2 to 20 wt % of one or more terphenyl compounds selected from the compounds of the formulae VI-1 to VI-25.

[0399] In another preferred embodiment of the present invention, the LC medium additionally comprises one or more compounds of the formulae VII-1 to VII-9

[0400]

[0401]

[0402] in

[0403] R 1 Each independently has the formula IIA for R 21 One of the meanings of the indication, and

[0404] w and x each independently represent 1 to 6.

[0405] Particular preference is given to LC media which comprise at least one compound of the formula VII-9.

[0406] The LC medium comprises one or more substances containing tetrahydronaphthyl or naphthyl units, for example compounds of formulae N-1 to N-5,

[0407]

[0408]

[0409] Where R 61 and R 62 Each independently has a 21 The indicated meanings preferably represent straight-chain alkyl, straight-chain alkoxy or straight-chain alkenyl, and

[0410] Z 61 and Z62 Each independently represents -C2H4-, -CH=CH-, -(CH2)4-, -(CH2)3O-, -O(CH2)3-, -CH=CHCH2CH2-, -CH2CH2CH=CH-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CF=CH-, -CH=CF-, -CF2O-, -OCF2-, -CH2- or a single bond.

[0411] c) an LC medium comprising one or more compounds selected from the following: a difluorodibenzochroman compound of formula BC, a chroman compound of formula CR, and fluorinated phenanthrene compounds of formulas PH-1 and PH-2,

[0412]

[0413] wherein

[0414] R 71 and R 72 each independently has the meaning of R 21 and c is 0, 1 or 2. R 71 and R 72 preferably each independently represents an alkyl or alkoxy group having 1 - 6 C atoms.

[0415] The LC medium according to the invention preferably contains the compounds of formulas BC, CR, PH-1, PH-2 in an amount of 3 to 20 wt%, in particular 3 to 15 wt%.

[0416] Particularly preferred compounds of formulas BC and CR are compounds BC-1 to BC-7 and CR-1 to CR-5,

[0417]

[0418]

[0419] wherein

[0420] alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 - 6 C atoms, and

[0421] alkenyl and alkenyl* each independently represent a straight-chain alkenyl group having 2 - 6 C atoms.

[0422] A very particularly preferred LC medium contains one, two or three compounds of formulas BC-2, BF-1 and / or BF-2.

[0423] d) an LC medium comprising one or more indan compounds of formula In,

[0424]

[0425] wherein

[0426] R 81 , R 82 , R 83 each independently of the others represents a straight-chain alkyl, alkoxy, alkoxyalkyl or alkenyl having 1 to 6 C atoms.

[0427] R 82 and R 83 may also represent halogen, preferably F,

[0428] represents

[0429]

[0430] i represents 0, 1 or 2.

[0431] Preferred compounds of formula In are the compounds of formulae In-1 to In-16 indicated below:

[0432]

[0433]

[0434]

[0435] Particularly preferred are the compounds of formulae In-1, In-2, In-3 and In-4.

[0436] The compounds of formula In and sub-formulae In-1 to In-16 are preferably used in the LC medium according to the invention in a concentration of ≥ 5 wt%, in particular 5 - 30 wt% and very particularly preferably 5 - 25 wt%.

[0437] e) an LC medium comprising one or more compounds of formulae L-1 to L-8,

[0438]

[0439]

[0440] wherein

[0441] R L1 to R L2 each independently of the others have the meanings indicated above for R 21 in formula IIA, alkyl represents an alkyl having 1 to 6 C atoms, and s represents 1 or 2.

[0442] The compounds of formulae L-1 to L-8 are preferably used at a concentration of 5 to 15 wt%, in particular 5 to 12 wt%, very particularly preferably 8 to 10 wt%.

[0443] f) The preferred LC medium additionally contains one or more compounds of formula IIA-Y

[0444]

[0445] wherein R 11 and R 12 have one of the meanings given above for R 21 in formula IIA, L 1 and L 2 independently of one another represent F or Cl, identically or differently.

[0446] The preferred compounds of formula IIA-Y are selected from the following sub-formulae

[0447]

[0448]

[0449]

[0450] wherein, Alkyl and Alkyl * each independently of one another represent a straight-chain alkyl having 1-6 C atoms, Alkoxy represents a straight-chain alkoxy having 1-6 C atoms, Alkenyl and Alkenyl * each independently of one another represent a straight-chain alkenyl having 2-6 C atoms, and O represents an oxygen atom or a single bond. Alkenyl and Alkenyl * preferably represent CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0451] The particularly preferred compounds of formula IIA-Y are selected from the following sub-formulae:

[0452]

[0453] wherein Alkoxy and Alkoxy * have the meanings defined above and preferably represent methoxy, ethoxy, n-propoxy, n-butoxy or n-pentyloxy.

[0454] g) An LC medium comprising one or more terphenyl compounds selected from the following formulae:

[0455]

[0456] wherein

[0457] 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,

[0458] X Q is F, Cl, a haloalkyl or alkoxy having 1 - 6 C atoms, or a haloalkenyl or alkenyloxy having 2 - 6 C atoms,

[0459] L Q1 -L Q6 are each independently H or F, where at least one of the L Q1 -L Q6 is F.

[0460] Preferred compounds of formula Q are those in which R Q represents a straight-chain alkyl having 2 - 6 C atoms, very preferably those being ethyl, n-propyl or n-butyl.

[0461] Preferred compounds of formula Q are those in which L Q3 and L Q4 are F. Further preferred compounds of formula Q are those in which one or both of L Q1 and L Q2 and L Q3 、L Q4 are F.

[0462] Preferred compounds of formula Q are those in which X Q represents F or OCF3, very preferably those being F.

[0463] Compounds of formula Q are preferably selected from the following sub-formulas

[0464]

[0465] wherein R Q has one of the meanings of formula Q, or one of its preferred meanings given above and below, and is preferably ethyl, n-propyl or n-butyl.

[0466] Particularly preferred are compounds of formula Q1, especially those in which R Q is n-propyl.

[0467] Preferably, in the LC medium, the proportion of the compound of formula Q is >0 to ≤5 wt%, very preferably 0.05 to 2 wt%, more preferably 0.1 to 1 wt%, and most preferably 0.1 to 0.8 wt%.

[0468] Preferably, the LC medium contains 1 to 5, preferably 1 or 2 compounds of formula Q.

[0469] Adding a terphenyl compound of formula Q to the LC mixture of the polymerizable LC medium enables reduction of ODF non-uniformity while maintaining high UV absorption, which enables rapid and complete polymerization, enables strong and rapid tilt angle generation, and improves the UV stability of the LC medium.

[0470] Furthermore, adding a compound of formula Q having positive dielectric anisotropy to an LC medium having negative dielectric anisotropy allows better control of the dielectric constants ε || and ε ⊥ values, and particularly enables achieving a high dielectric constant ε || value while maintaining the dielectric anisotropy Δη constant, thereby reducing the kick-back voltage and reducing image retention.

[0471] The LC medium according to the invention preferably comprises

[0472] - one or more compounds of formula L1 or its sub-formulas, preferably selected from sub-formulas L1-1 to L1-3, very preferably selected from sub-formula L1-2, preferably in a proportion of 0.1 to 10%, very preferably 0.2 to 5%, most preferably 0.3 to 3%, by weight,

[0473] and / or

[0474] - one or more compounds of formula L2 or its sub-formulas, preferably selected from sub-formulas L2-1 to L2-3, very preferably selected from sub-formula L2-1, preferably in a total concentration range of 0.1 to 10%, very preferably 0.2 to 5%, most preferably 0.3 to 3%, by weight,

[0475] and / or

[0476] - one or more compounds of formula IV, preferably in a total concentration in the range of 10% to 60%, more preferably 15% to 55%, particularly preferably 20% to 40%;

[0477] and / or

[0478] - one or more compounds of formula III, preferably the compound of formula III-2, very preferably the compound of formula III-2-1, preferably in a total concentration in the range of 2% to 25%, very preferably 4% to 15%;

[0479] and / or

[0480] -One or more compounds of formula III-3-2, preferably formula III-3-2-3 or III-3-2-4, preferably in a total concentration in the range of 2% to 25%, very preferably 4% to 15%,

[0481] and / or

[0482] -One or more compounds of formula III-10, preferably selected from formulae III-10-1 to III-10-11, preferably in a total concentration in the range of 2% to 25%, very preferably 4% to 15%,

[0483] and / or

[0484] -One or more compounds of formula IID-1 and / or IID-4, preferably in a total concentration in the range of 0.5% to 15%, very preferably 0.5% to 8%,

[0485] and / or

[0486] -One or more compounds selected from formulae IID-1, IID-15, IID-17, IID-18, IID-19, IID-20, IID-21, IID-22 and IID-23, very preferably selected from formulae IID-1, IID-21, IID-22 and IID-23, preferably in a total concentration in the range of 0.5% to 15%, very preferably 0.5% to 8%.

[0487] In particular, the LC medium comprises

[0488] -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 in the range of 5% to 30%, preferably 10% to 20% based on the overall mixture,

[0489] -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 in the range of 5% to 40%, preferably 10% to 30% based on the overall mixture,

[0490] and / or

[0491] -One or more compounds CPY-n-Om, in particular CPY-2-O2, CPY-3-O2 and / or CPY-5-O2, preferably in a concentration of >5%, in particular 7% to 20% based on the overall mixture;

[0492] and / or

[0493] -One or more compounds CCY-n-Om, preferably CCY-4-O2, CCY-3-O2, CCY-3-O3, CCY-3-O1 and / or CCY-5-O2, preferably at a concentration of > 3%, in particular 5 to 15%, based on the total of the mixture,

[0494] and / or

[0495] -One or more compounds CPY-n-Om and CY-n-Om, preferably at a concentration of 10 to 80% based on the total of the mixture,

[0496] and / or

[0497] -One or more compounds CPY-n-Om and PY-n-Om, preferably CPY-2-O2 and / or CPY-3-O2 and PY-3-O2 or PY-1-O2, preferably at a concentration of 5 to 20%, more preferably 10 to 15%, based on the total of the mixture,

[0498] and / or

[0499] -One or more compounds selected from CCH-13, CCH-23, CCH-34, CCH-35, CCH-301 and CCH-303, preferably at a total concentration of 3 to 40%, preferably 3 to 25%, based on the total of the mixture,

[0500] and / or

[0501] -One or more compounds selected from CC-2-V1, CC-3-V1, CC-3-V2, CC-4-V1, CC-3-2V1, CC-3-V, CC-4-V, CC-5-V, CC-V-V, CC-V-V1, CC-1V-V1 and CC-2V-V2, preferably at a total concentration of 3 to 60%, more preferably 3 to 40%, very preferably 5% to 30%, based on the total of the mixture,

[0502] and / or

[0503] -One or more compounds CC-3-V, preferably at a total concentration of ≥ 10%, more preferably ≥ 15%, very preferably 20% to 60%, most preferably 20% to 40%, based on the total of the mixture,

[0504] and / or

[0505] -One or more compounds CCP-n-m and / or CCP-Vn-m and / or CPP-n-m, which are preferably selected from CCP-3-1, CCP-V-1, CCP-V2-1 and CPP-3-2, preferably at a total concentration of 4 to 35%, preferably 5 to 25%, based on the total of the mixture,

[0506] and / or

[0507] - one or more compounds CLP-n-m and / or CLP-Vn-m, preferably selected from CLP-3-1, CLP-3-2 and CLP-V-1, preferably with a total concentration of 1 to 25%, preferably 2 to 15%, based on the overall mixture,

[0508] and / or

[0509] - one or more compounds PGP-n-m, preferably selected from PGP-2-3, PGP-2-4, PGP-2-5, PGP-3-5, preferably with a total concentration of 2 to 20%, more preferably 2% to 15%, most preferably 2 to 10%, based on the overall mixture,

[0510] and / or

[0511] - one or more compounds selected from PYP-n-m, PGIY-n-Om and PGP-n-2V, preferably selected from PGP-1-2V, PGP-2-2V and PGP-3-2V, preferably with a total concentration of 2 to 20%, more preferably 2% to 15%, most preferably 2 to 10%, based on the overall mixture,

[0512] and / or

[0513] - one or more compounds PP-n-m and / or PP-n-nVm, preferably selected from PP-1-3, PP-1-4, PP-1-5, PP-1-2V and PP-1-2V1, preferably with a total concentration of 1 to 15%, preferably 2 to 10% based on the overall mixture

[0514] and / or

[0515] - compound CCG-V-F, preferably with a concentration of 0.5% to 10% based on the overall mixture,

[0516] and / or

[0517] - compound PPGU-3-F, preferably with a concentration of 0.1% to 3% based on the overall mixture.

[0518] Advantageously, the liquid crystal medium according to the invention preferably has a nematic phase from ≤ -20 °C to ≥ 70 °C, particularly preferably from ≤ -30 °C to ≥ 80 °C, very particularly preferably from ≤ -40 °C to ≥ 90 °C.

[0519] The LC medium according to the invention preferably has a clearing temperature of 70 °C or higher, preferably 74 °C or higher.

[0520] Here, the expression "having a nematic phase" means on the one hand that no smectic phase and no crystallization are observed at low temperatures at the corresponding temperature, and on the other hand that no clearing occurs when heating from said nematic phase. The studies at low temperatures were carried out in a flow viscometer at the corresponding temperature and checked by storing in a test cell having a layer thickness corresponding to electro-optical applications for at least 100 hours. If the storage stability at a temperature of -20 °C in the corresponding test cell is 1000 hours or higher, the LC medium is said to be stable at this temperature. At temperatures of -30 °C and -40 °C, the corresponding times are 500 hours and 250 hours, respectively. At high temperatures, the clearing point was measured in a capillary by a conventional method.

[0521] The liquid crystal mixture preferably has a nematic range of at least 60 K and a kinematic viscosity ν of at most 30 mm 2 ·s -1 at 20 °C. 20 .

[0522] The mixture is nematic at a temperature of -20 °C or lower, preferably at -30 °C or lower, and very preferably at -40 °C or lower.

[0523] The value of the birefringence Δn in the liquid crystal mixture is generally between 0.08 and 0.17, preferably between 0.09 and 0.165, and very preferably between 0.10 and 0.16. In a preferred embodiment of the present invention, the LC medium has a birefringence in the range of 0.11 to 0.155.

[0524] The liquid crystal mixture according to the present invention has a dielectric anisotropy Δε of -1.5 to -8.0, preferably -2.0 to -5.0, and especially -2.5 to -4.8.

[0525] The rotational viscosity γ1 at 20 °C is preferably ≤200 mPa·s, more preferably ≤180 mPa·s, very preferably ≤125 mPa·s, and most preferably ≤115 mPa·s. In another preferred embodiment, the rotational viscosity γ1 at 20 °C is ≤110 mPa·s, especially ≤105 mPa·s.

[0526] The liquid crystal medium according to the present invention has a relatively low threshold voltage (V0) value. They are preferably in the range of 1.7 V to 3.0 V, particularly preferably ≤2.7 V and very particularly preferably ≤2.5 V.

[0527] For the present invention, unless otherwise expressly stated, the term "threshold voltage" relates to the capacitive threshold (V0) also known as the Freedericks threshold.

[0528] Furthermore, the liquid crystal medium according to the invention has a high voltage holding ratio value in a liquid crystal cell.

[0529] Typically, liquid crystal media with low addressing voltages or threshold voltages exhibit lower voltage holding ratios than those with higher addressing voltages or threshold voltages, and vice versa.

[0530] For the present invention, the term "dielectrically positive compound" denotes a compound having Δε > 1.5, the term "dielectrically neutral compound" denotes those compounds having -1.5 ≤ Δε ≤ 1.5, and the term "dielectrically negative compound" denotes those compounds having Δε < -1.5. The dielectric anisotropy of the compounds is determined herein by dissolving 10% of the compound in the liquid crystal host and measuring the capacitance of the resulting mixture in at least one test cell at 1 kHz, in the case of using vertical alignment and in the case of using planar alignment, the cell having a layer thickness of 20 μm in each case. The measuring voltage is typically 0.5 V to 1.0 V, but always below the capacitance threshold of the respective liquid crystal mixture under investigation.

[0531] All temperature values indicated in the present invention are in °C.

[0532] The LC medium according to the invention is suitable for all VA-TFT (vertical alignment thin film transistor) applications, for example, VAN (vertical alignment nematic), MVA (multi-domain VA), (S)-PVA (super patterned VA), ASV (advanced super view, or axially symmetric VA), PSA (polymer sustained VA) and PS-VA (polymer stabilized VA). They are also suitable for IPS (in-plane switching) and FFS (fringe field switching) applications with negative Δε.

[0533] The nematic LC medium in a display according to the invention typically comprises two components A and B, which themselves consist of one or more individual compounds.

[0534] Component A has a significantly negative dielectric anisotropy and renders the dielectric anisotropy of the nematic phase ≤ -0.5. It preferably further comprises one or more of the compounds of formulae IIA, IIB, IIC and / or IID, and in addition one or more compounds of formula III.

[0535] The proportion of component A is preferably between 45 and 100%, in particular between 60 and 85%.

[0536] For component A, it is preferred to select one (or more) individual compounds having a Δε value of ≤ -1.5. The smaller the proportion A in the overall mixture, the more negative this value must be.

[0537] Component B has significant nematogeneity and a flow viscosity of not more than 30 mm 2 ·s -1 at 20 °C, preferably not more than 25 mm 2 ·s -1 .

[0538] A large number of suitable materials are known to those skilled in the art from the literature. Compounds of formula IV are particularly preferred.

[0539] Particularly preferred individual compounds in component B are very low viscosity nematic liquid crystals having a flow viscosity of not more than 18 mm 2 ·s -1 at 20 °C, preferably not more than 12 mm 2 ·s -1 .

[0540] Component B is monotropically or enantiotropically nematic, does not have a smectic phase, and is capable of preventing the appearance of a smectic phase in the LC medium at low to very low temperatures. For example, if various highly nematogenic materials are added to a smectic liquid crystal mixture, the nematogeneity of these materials can be compared by the degree of suppression of the smectic phase achieved.

[0541] The mixture may optionally further comprise 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% by weight based on the total of the mixture.

[0542] In addition to the polymerizable compounds and compounds of formula L1 and / or L2, the LC medium preferably comprises 4 to 15, especially 5 to 12, and particularly preferably < 10 compounds of formula IIA, IIB, IIC and / or IID, and one or more compounds of formula IV.

[0543] In addition to the polymerizable compounds and compounds of formula L1 and / or L2 and compounds of formula IIA, IIB, IIC and / or IID and IV, other components may be present, for example in an amount of at most 45%, but preferably at most 35%, especially at most 10% of the total mixture.

[0544] The other components are preferably selected from nematic or nematogenic substances, in particular from known substances of the following classes: azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, phenyl benzoates or cyclohexyl benzoates, phenyl cyclohexanecarboxylates or cyclohexyl cyclohexanecarboxylates, phenylcyclohexanes, cyclohexylbiphenyls, cyclohexylcyclohexanes, cyclohexylnaphthalenes, 1,4-biscyclohexylbiphenyls or cyclohexylpyrimidines, phenyl dioxanes or cyclohexyl dioxanes, optionally halogenated stilbenes, benzyl phenyl ethers, diphenylacetylenes and substituted cinnamic acid esters.

[0545] The most important compounds suitable as components of a liquid-crystalline phase of this type can be represented by the formula R

[0546] R R1 -L-G-E-R R2 R

[0547] wherein L and E each represent a carbocyclic or heterocyclic ring system which is a group formed from: 1,4-disubstituted benzene and cyclohexane rings, 4,4'-disubstituted biphenyls, phenylcyclohexane and cyclohexylcyclohexane systems, 2,5-disubstituted pyrimidines and 1,3- alkane rings, 2,6-disubstituted naphthalenes, dihydronaphthalenes and tetrahydronaphthalenes, quinazolines and tetrahydroquinazolines,

[0548] G represents -CH=CH--N(O)=N-

[0549] -CH=CQ--CH=N(O)-

[0550] -C≡C--CH2-CH2-

[0551] -CO-O--CH2-O-

[0552] -CO-S--CH2-S-

[0553] -CH=N--COO-Phe-COO-

[0554] -CF2O--CF=CF-

[0555] -OCF2--OCH2-

[0556] -(CH2)4--(CH2)3O-

[0557] or a C-C single bond,

[0558] Q represents a halogen, preferably chlorine, or -CN, and

[0559] R R1 and R R2Each represents an alkyl, alkenyl, alkoxy, alkoxyalkyl or alkoxycarbonyloxy group having at most 18, preferably at most 8 carbon atoms, or alternatively one of these groups represents CN, NC, NO2, NCS, CF3, SF5, OCF3, F, Cl or Br.

[0560] In most of these compounds, R R1 and R R2 are different from each other, and one of these groups is usually an alkyl or alkoxy group. Other variants of the proposed substituents are also common. Many such substances or their mixtures are commercially available. All of these substances can be prepared by methods known from the literature.

[0561] It is self-evident to those skilled in the art that the VA, IPS or FFS mixtures according to the invention may also contain compounds in which, for example, H, N, O, Cl and F have been replaced by the corresponding isotopes.

[0562] The LC medium preferably has a nematic LC phase.

[0563] The LC medium further contains two or more polymerizable compounds, which are preferably selected from polymerizable mesogenic compounds, which are also referred to as "reactive mesogens" or RMs, and very preferably selected from the formula M as described above.

[0564] Among the polymerizable compounds, the polymerizable group P is a group suitable for a polymerization reaction (such as free radical or ionic chain polymerization, addition polymerization or condensation polymerization) or suitable for a polymer-analogous transformation reaction (such as addition or condensation to the polymer backbone). Groups particularly preferred for chain polymerization are, in particular, those containing a C═C double bond or a -C≡C- triple bond, and groups suitable for polymerization in the case of ring opening, such as oxetane or epoxy groups.

[0565] Preferred groups P are selected from CH2═CW 1 -CO-O-, CH2═CW 1 -CO-,

[0566]

[0567] CH2═CW 2 -(O) k3 -, CW 1 ═CH-CO-(O) k3 -, CW 1 ═CH-CO-NH-,

[0568] CH2═CW 1 -CO-NH-, CH3-CH═CH-O-, (CH2═CH)2CH-OCO-,

[0569] (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, HO-CW 2 W 3 -, HS-CW 2 W 3 -, HW 2 N-, HO-CW 2 W 3 -NH-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -, CH2=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, CF3, phenyl or an alkyl group having 1 to 5 C atoms, especially H, F, Cl or CH3, W 2 and W 3 each independently of one another represents H or an alkyl group having 1 to 5 C atoms, especially H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently of one another represents Cl, an oxaalkyl group or an oxacarbonylalkyl group having 1 to 5 C atoms, W 7 and W 8 each independently of one another represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, which is optionally substituted by one or more groups L other than P-Sp- as defined above, k1, k2 and k3 each independently of one another represent 0 or 1, k3 preferably represents 1, and k4 represents an integer from 1 to 10.

[0570] Very preferred groups P are selected from CH2=CW 1 -CO-O-, CH2=CW 1 -CO-,

[0571]

[0572] CH2=CW 2 -O-, CH2=CW 2 -, CW 1 =CH-CO-(O) k3 -, CW1 =CH-CO-NH-, CH2=CW 1 -CO-NH-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -, CH2=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, CF3, phenyl or an alkyl group having 1 to 5 C atoms, in particular H, F, Cl or CH3, W 2 and W 3 each independently of one another represents H or an alkyl group having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently of one another represents Cl, an oxaalkyl group or an oxacarbonylalkyl group having 1 to 5 C atoms, W 7 and W 8 each independently of one another represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, k1, k2 and k3 each independently of one another represent 0 or 1, k3 preferably represents 1, and k4 represents an integer from 1 to 10.

[0573] Very particularly preferred groups P are selected from CH2=CW 1 -CO-O-, in particular CH2=CH-CO-O-, CH2=C(CH3)-CO-O- and CH2=CF-CO-O-, and also CH2=CH-O-, (CH2=CH)2CH-O-CO-, (CH2=CH)2CH-O-,

[0574] Further preferred polymerizable groups P are selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, most preferably from acrylate and methacrylate.

[0575] Very preferably, all polymerizable groups in the polymerizable compound have the same meaning.

[0576] If the spacer group Sp is not a single bond, it is preferably a spacer group of the formula Sp"-X", so that the corresponding group P-Sp- corresponds to the formula P-Sp"-X"-, where

[0577] Sp" represents a straight-chain or branched alkylene group having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, and in which furthermore one or more non-adjacent CH2 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,

[0578] 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 )-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -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,

[0579] R 0 and R 00 each independently of one another represent H or an alkyl group having 1 to 20 C atoms, and

[0580] Y 2 and Y 3 each independently of one another represent H, F, Cl or CN.

[0581] X" is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -, -NR0 -CO-, -NR 0 -CO-NR 00 - or a single bond.

[0582] Typical spacer groups Sp and -Sp"-X"- are, for example, -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -O-CO-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO-O-, -(CH2CH2O) q1 -CH2CH2-, -CH2CH2-S-CH2CH2-, -CH2CH2-NH-CH2CH2- 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 has the meaning indicated above.

[0583] Particularly preferred spacer groups Sp and -Sp"-X"- are -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -O-CO-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO-O-, where p1 and q1 have the meaning indicated above.

[0584] Particularly preferred groups Sp" are, in each case, straight-chain ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethyl-N-methyliminoethylene, 1-methylalkylene, vinyl, propenyl and butenyl.

[0585] In a preferred embodiment of the invention, the polymerizable compound contains a spacer group Sp which is substituted by one or more polymerizable groups P such that the group Sp-P corresponds to Sp(P) s , where s is ≥2 (branched polymerizable groups).

[0586] Preferred polymerizable compounds according to this preferred embodiment are those in which s is 2, i.e. compounds containing the group Sp(P)2. Highly preferred polymerizable compounds according to this preferred embodiment contain a group selected from the following formulae:

[0587]

[0588] wherein P is as defined in formula M,

[0589] alkyl represents a single bond or a straight-chain or branched alkylene group having 1 to 12 C atoms, which is unsubstituted or mono- or polysubstituted by F, Cl or CN, and wherein one or more non-adjacent CH2 groups may each independently of one another be replaced by -C(R 0 )=C(R 0 )-, -C≡C-, -N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly linked to one another, where R 0 has the meaning indicated above,

[0590] aa and bb each independently of one another represent 0, 1, 2, 3, 4, 5 or 6,

[0591] X has one of the meanings indicated for X", and is preferably O, CO, SO2, O-CO-, CO-O or a single bond.

[0592] Preferred spacer groups Sp(P)2 are selected from formulae S1, S2 and S3.

[0593] Very preferred spacer groups Sp(P)2 are selected from the following sub-formulae:

[0594]

[0595] P is preferably selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, very preferably from acrylate and methacrylate, and most preferably from methacrylate.

[0596] Further preferably, all polymerizable groups P present in the same compound have the same meaning, and very preferably represent acrylate or methacrylate, most preferably methacrylate.

[0597] Sp preferably represents a single bond or -(CH2) p1 -, -(CH2) p2 -CH=CH-(CH2) p3 -, -O-(CH2) p1 -, -O-CO-(CH2) p1 or -CO-O-(CH2) p1, where p1 is 2, 3, 4, 5 or 6, preferably 2 or 3, p2 and p3 are independently of each other 0, 1, 2 or 3, and if Sp is -O-(CH2) p1 -, -O-CO-(CH2) p1 or -CO-O-(CH2) p1 , then the O atom or the CO group is attached to the benzene ring respectively.

[0598] More preferably, at least one group Sp is a single bond.

[0599] More preferably, at least one group Sp is not a single bond and is preferably selected from -(CH2) p1 -, -(CH2) p2 -CH=CH-(CH2) p3 -, -O-(CH2) p1 -, -O-CO-(CH2) p1 or -CO-O-(CH2) p1 , where p1 is 2, 3, 4, 5 or 6, preferably 2 or 3, p2 and p3 are independently of each other 0, 1, 2 or 3, and if Sp is -O-(CH2) p1 -, -O-CO-(CH2) p1 or -CO-O-(CH2) p1 , then the O atom or the CO group is attached to the benzene ring respectively.

[0600] Very preferably, Sp is not a single bond and is selected from -(CH2)2-, -(CH2)3-, -(CH2)4-, -O-(CH2)2-, -O-(CH2)3-, -O-CO-(CH2)2 and -CO-O-(CH)2-, where the O atom or the CO group is attached to the benzene ring.

[0601] Particularly preferred compounds of formula M are those compounds in which B 1 and B 2Each independently represents 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl, naphthalene-2,6-diyl, phenanthrene-2,7-diyl, 9,10-dihydrophenanthrene-2,7-diyl, anthracene-2,7-diyl, fluorene-2,7-diyl, coumarin, flavone, wherein one or more CH groups in these groups may further be replaced by N, cyclohexane-1,4-diyl, wherein one or more non-adjacent CH₂ groups may further be replaced by O and / or S, 1,4-cyclohexenylene, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, piperidine-1,4-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, indane-2,5-diyl or octahydro-4,7-methanoindane-2,5-diyl, and all of these groups may be unsubstituted or mono- or polysubstituted by L as defined above.

[0602] Particularly preferred compounds of formula M are those compounds wherein B 1 and B 2 each independently represents 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl.

[0603] Further preferred compounds of formula M are those compounds wherein the group -B 1 -(Z m -B 2 ) m - is selected from the following formulae

[0604]

[0605]

[0606] wherein at least one benzene ring is substituted by at least one group L, and the benzene ring is optionally further substituted by one or more groups L or P-Sp-.

[0607] Preferred compounds of formula M and its sub-formulae are selected from the following preferred embodiments, including any combination thereof:

[0608] — All groups P in the compound have the same meaning,

[0609] — -B 1 -(Z m -B 2 ) m - is selected from formulae A1, A2 and A5,

[0610] — The compound exactly contains two polymerizable groups (represented by group P),

[0611] — The compound exactly contains three polymerizable groups (represented by group P),

[0612] — P is selected from acrylate, methacrylate and oxetane, very preferably acrylate or methacrylate,

[0613] — P is methacrylate,

[0614] — All groups Sp are single bonds,

[0615] — At least one of the groups Sp is a single bond and at least one of the groups Sp is not a single bond,

[0616] — Sp, when not a single bond, is -(CH2) p2 -, -(CH2) p2 -O-, -(CH2) p2 -CO-O-, -(CH2) p2 -O-CO-, where p2 is 2, 3, 4, 5 or 6, and the O atom or the CO group is respectively connected to the benzene ring,

[0617] — Sp is a single bond or represents -(CH2) p2 -, -(CH2) p2 -O-, -(CH2) p2 -CO-O-, -(CH2) p2 -O-CO-, where p2 is 2, 3, 4, 5 or 6, and the O atom or the CO group is respectively connected to the benzene ring,

[0618] — R represents P-Sp-,

[0619] — R does not represent or contain a polymerizable group,

[0620] — R does not represent or contain a polymerizable group and represents a straight-chain, branched-chain or cyclic alkyl group having 1 to 25 C atoms, where one or more non-adjacent CH2 groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and / or S atoms are not directly connected to each other, and where one or more H atoms are each optionally replaced by F, Cl or L a replace,

[0621] — L or L' represents F, Cl or CN,

[0622] — L is F.

[0623] The compounds of formula M that are very preferably selected from the following formulas:

[0624]

[0625]

[0626]

[0627]

[0628]

[0629] Each of the groups, each time it appears, is the same or different and each is independent of the others and has the following meanings:

[0630] P 1 、P 2 、P 3 represents a polymerizable group, which is preferably selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy group, very preferably acrylate or methacrylate,

[0631] Sp 1 、Sp 2 、Sp 3 represents a single bond or a spacer group, wherein one or more of the groups P 1 -Sp 1 -、P 2 -Sp 2 - and P 3 -Sp 3 - may also represent R M , provided that at least one of the groups P 1 -Sp 1 -、P 2 -Sp 2 and P 3 -Sp 3 - is not R M , which preferably has one of the preferred meanings of Sp given above, very preferably -(CH2) p1 -、-(CH2) p1 -O-、-(CH2) p1 -CO-O- or -(CH2) p1 -O-CO-O-, where p1 is an integer from 1 to 12,

[0632] R M represents H, F, Cl, CN or a straight-chain or branched alkyl group having 1 to 25 C atoms, wherein one or more non-adjacent CH2 groups may also each be independently of the others replaced by -C(R 0 )=C(R 00 )-、-C≡C-、-N(R 0)-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- are replaced in such a way that the O and / or S atoms are not directly connected to each other, and in which furthermore one or more H atoms can also be replaced by F, Cl, CN or P 1 -Sp 1 - are replaced, particularly preferably by straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy groups having 1 to 12 C atoms (wherein the alkenyl and alkynyl groups have at least two C atoms, and the branched groups have at least three C atoms), and in which R M does not represent or contain a group P 1 、P 2 or P 3 ,

[0633] R 0 、R 00 represents H or an alkyl group having 1 to 12 C atoms,

[0634] R y and R z represent H, F, CH3 or CF3,

[0635] X 1 、X 2 、X 3 represent -CO-O-, -O-CO- or a single bond,

[0636] Z M1 represents -O-, -CO-, -C(R y R z )- or -CF2CF2-,

[0637] Z M2 、Z M3 represent -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -(CH2) n - where n is 2, 3 or 4,

[0638] L represents F, Cl, CN or a straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, thioalkyl, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 12 C atoms,

[0639] L', L" represent H, F or Cl,

[0640] k represents 0 or 1,

[0641] r represents 0, 1, 2, 3 or 4,

[0642] s represents 0, 1, 2 or 3,

[0643] t represents 0, 1 or 2,

[0644] x represents 0 or 1.

[0645] Compounds of the formulae M2, M13 and M32 are very preferred, especially those which exactly contain two polymerizable groups P 1 and P 2 and are bireactive compounds.

[0646] Further preferred are compounds selected from the formulae M17 to M31, especially those selected from the formulae M20, M22, M26, M29 and M31, especially those which exactly contain three polymerizable groups P 1 、P 2 and P 3 and are trireactive compounds.

[0647] In the compounds of the formulae M1 to M32, the group

[0648] is preferably

[0649]

[0650] wherein L, each time it appears, is the same or different and has one of the meanings given above and below, and is preferably F, Cl, CN, NO2, CH3, C2H5, C(CH3)3, CH(CH3)2, CH2CH(CH3)C2H5, -CH=CH2, C(CH3)=CH2, SCH3, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5 or P-Sp-, very preferably F, Cl, CN, CH3, C2H5, -CH=CH2, C(CH3)=CH2, SCH3, OCH3, COCH3, OCF3 or P-Sp-, more preferably F, Cl, CH3, -CH=CH2, C(CH3)=CH2, SCH3, OCH3, COCH3 or OCF3, and most preferably F, SCH3 or OCH3.

[0651] Preferred compounds of the formulae M1 to M32 are those compounds wherein 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.

[0652] Further preferred compounds of formulas M1 to M32 are those compounds in which Sp 1 、Sp 2 and Sp 3 are single bonds.

[0653] Further preferred compounds of formulas M1 to M32 are those compounds in which one of Sp 1 、Sp 2 and Sp 3 is a single bond, while the other of Sp 1 、Sp 2 and Sp 3 is not a single bond.

[0654] Further preferred compounds of formulas M1 to M32 are those compounds in which the groups Sp that are not single bonds 1 、Sp 2 and Sp 3 represent -(CH2) s1 -X"-, where s1 is an integer from 1 to 6, preferably 2, 3, 4 or 5, and X" is a bond connected to the benzene ring and is -O-, -O-CO-, -CO-O-, -O-CO-O- or a single bond.

[0655] Further preferred polymerizable compounds are selected from Table E below, especially from formulas RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM-40, RM-41, RM-48, RM-52, RM-54, RM-57, RM-58, RM-64, RM-74, RM-76, RM-88, RM-91, RM-102, RM-103, RM-109, RM-116, RM-117, RM-120, RM-121, RM-122, RM-139, RM-140, RM-142, RM-143, RM-145, RM-146, RM-147, RM-149, RM-156 to RM-163, RM-169, RM-170 and RM-171 to RM-183.

[0656] Particularly preferred is an LC medium comprising two, three or more polymerizable compounds of formula M.

[0657] Further preferred is an LC medium comprising two or more di-reactive polymerizable compounds of formula M, which formula M is preferably selected from formulas M1 to M16 and M32, and very preferably selected from formulas M2, M13 and M32.

[0658] Further preferred is an LC medium comprising one or more di-reactive polymerizable compounds of formula M, said formula M being preferably selected from formulas M1 to M16 and M32, very preferably selected from formulas M2, M13 and M32, and one or more tri-reactive polymerizable compounds of formula M, said formula M being preferably selected from formulas M17 to M32, very preferably selected from formulas M20, M22, M26, M29 and M31.

[0659] Further preferred is an LC medium comprising one or more polymerizable compounds of formula M, wherein at least one of r is not 0, or at least one of s and t is not 0, said formula M being very preferably selected from formulas M2, M13, M22, M24, M27, M29, M31 and M32, and wherein L is selected from the preferred groups shown above, most preferably selected from F, OCH3 and SCH3.

[0660] Further preferred is an LC medium comprising one or more polymerizable compounds that exhibit absorption in the wavelength range of 320 to 380 nm, preferably selected from formula M, very preferably selected from formulas M1 to M32.

[0661] Particularly preferred is an LC medium comprising two or more, very preferably two or three, polymerizable compounds selected from formula M or formulas M1 to M32.

[0662] The combination of the compounds of the preferred embodiments mentioned above with the polymerizable compounds described above and below results in a low threshold voltage, low rotational viscosity and very good low-temperature stability in the LC medium according to the invention, while resulting in constant high-definition bright points and high HR values and allowing for a particularly low tilt angle (i.e., large tilt) to be quickly established in a PSA display. In particular, the LC medium exhibits a significantly shortened response time, especially the gray-scale response time, compared to LC media of the prior art in a PSA display.

[0663] For use in a PSA display, the total proportion of the polymerizable compounds (such as those of formula M or M1 to M32) in the LC medium is preferably from 0.01 to 2.0%, very preferably from 0.1 to 1.0%, and most preferably from 0.2 to 0.8%.

[0664] For use in an SA-VA display, the total proportion of the polymerizable compounds (such as those of formula M or M1 to M32) in the LC medium is preferably >0 to <3%, very preferably >0 to <2%, more preferably 0.05 to 2.0, and most preferably 0.05 to 1.0%.

[0665] In a preferred embodiment of the invention, the LC medium comprises two or more polymerizable compounds of formula M selected from formulas IA, IB and IC:

[0666] P-Sp-M 1 -Sp-P IA

[0667] P-Sp-M 2 -Sp-P IB

[0668] P-Sp-M 3 -Sp-P IC

[0669] Each group is the same or different each time it appears, and each independently of one another has the following meanings:

[0670] P is a polymerizable group,

[0671] Sp is a spacer group or a single bond, which is optionally substituted by L a substituted,

[0672] M 1 ,M 2 ,M 3 is a group independently selected from the following formulas:

[0673]

[0674] wherein the benzene ring is optionally substituted by one or more groups L or P-Sp-,

[0675] L is L a ,L b ,F, Cl, -CN, P-Sp-, or a straight-chain, branched-chain or cyclic alkyl group having 1 to 25 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a 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 replaced by P, F or Cl,

[0676] L a is -C(R aa )(R bb )OH,

[0677] R aa ,R bb is a straight-chain alkyl group having 1 to 6 C atoms, or optionally R aa and R bb together with the C atom to which they are attached form a cyclic alkyl group having 3 to 12 C atoms, very preferably cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl,

[0678] L b is a straight-chain or branched-chain alkenyl group having 2 to 7 C atoms, preferably 3 or 4 C atoms,

[0679] Among the compounds of formula IA, the group M 1 and / or at least one spacer group Sp is mono-substituted by L a at least monosubstituted,

[0680] and among the compounds of formula IC, the group M 3 is mono-substituted by L b at least monosubstituted.

[0681] In a preferred embodiment of the present invention, the compounds of formula IA and its sub-formulas contain a spacer group Sp substituted by one or more, preferably one group L a substituted spacer group Sp.

[0682] In the compounds of formula IA and its sub-formulas, R aa and R bb preferably represent a straight-chain alkyl group having 1 to 6 C atoms or a branched-chain alkyl group having 3 to 6 C atoms. More preferably, R aa and R bb independently of one another represent methyl, ethyl, propyl and butyl, very preferably methyl or ethyl, and most preferably methyl.

[0683] Further preferred are the compounds of formula IA and its sub-formulas as described above and below, wherein R aa and R bb together with the C atom to which they are attached form a cyclic alkyl group having 3 - 12 C atoms, very preferably cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

[0684] Very preferably, the compounds of formula IA contain a group L selected from the following formulas a

[0685]

[0686]

[0687] wherein the asterisk represents the connection to the adjacent group in the compound of formula I.

[0688] In another preferred embodiment of the present invention, the compounds of formula IA and its sub-formulas contain a spacer group Sp which is a straight-chain or branched-chain alkylene group having 1 to 12, preferably 1 to 7 C atoms, and the alkylene group is substituted by one or more groups L a substituted. Preferred compounds of formula IA according to this preferred embodiment contain a group P-Sp- selected from the following formulas

[0689] P-CHL a - SL1

[0690] P-(CH2) cc -O-CHL a - SL2

[0691] P-(CH2) cc -CO-O-CHL a - SL3

[0692] P-(CH2) cc -CHL a - SL4

[0693] wherein P and L a are as defined in formula I or have one of the meanings given in the context, and cc is 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3.

[0694] Preferred compounds of formula I contain one or more groups P-Sp-, which are selected from formulae SL1, SL2 and SL3, very preferably formula SL1.

[0695] Preferably, in the compounds of formula IA, M 1 is selected from formulae 1 or 2.

[0696] Preferred compounds of formula IA are selected from the following sub-formulae:

[0697]

[0698]

[0699]

[0700] wherein P, Sp and L have the meanings given in formula IA or one of the preferred meanings given in the context,

[0701] r1, r2, r3 are independently of one another 0, 1, 2, 3 or 4,

[0702] r4 is 0, 1, 2 or 3,

[0703] wherein the compound contains at least one group Sp which is at least monosubstituted by L a and / or at least one group L which represents L a of the group.

[0704] Very preferred compounds of sub-formulae IA-1 to IA-10 are those in which all groups P are the same and represent acrylate or methacrylate (preferably methacrylate).

[0705] Further preferred compounds of sub-formulae IA-1 to IA-10 are those in which at least one group Sp represents a single bond.

[0706] Further preferred compounds of sub-formulas IA-1 to IA-10 are those in which one group Sp is selected from formulas SL1 to SL4, very preferably from formula SL1, and the other group Sp represents a single bond, or, if different from a single bond, represents -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -O-CO- or -(CH2) p1 -CO-O-, where p1 is an integer from 1 to 12, preferably an integer from 1 to 6, and the O- or CO group is attached to the benzene ring, very preferably where the other group Sp represents a single bond.

[0707] Other preferred compounds of formula IA and its sub-formulas are selected from the following preferred embodiments, including any combination thereof:

[0708] -All groups P in the compound have the same meaning,

[0709] -M a having formula 1 or 2, very preferably formula 1,

[0710] -The compound contains exactly two polymerizable groups (represented by group P),

[0711] --The compound contains exactly three polymerizable groups (represented by group P),

[0712] -P is selected from acrylate, methacrylate and oxetane, very preferably acrylate or methacrylate,

[0713] -The compound contains at least one (preferably exactly one) group Sp, which is substituted by L a and is preferably selected from formulas SL1 - SL4, very preferably from formulas SL1, SL2 and SL3,

[0714] -Sp, when different from a single bond, is -(CH2) p2 -, -(CH2) p2 -O-, -(CH2) p2 -CO-O-, -(CH2) p2 -O-CO-, where p2 is 2, 3, 4, 5 or 6, and the O atom or CO group is attached to the benzene ring respectively,

[0715] -Sp' is selected from formula SL1,

[0716] -L represents F, Cl, CH3, C2H5, OCH3 or OC2H5, very preferably F,

[0717] -L’ represents F, Cl, CH3, C2H5, OCH3 or OC2H5, very preferably F,

[0718] -L a represents -C(CH3)2-OH, -C(C2H5)2-OH or -C(CH3)(C2H5)OH, very preferably -C(CH3)2-OH,

[0719] -r1, r2, r3 and r4 represent 0 or 1,

[0720] -r1 + r2 is 0,

[0721] -r1 + r2 is 1,

[0722] -r3 is 0,

[0723] -r4 is 0.

[0724] Compounds of formula IA and its sub-formulas that are very preferred are selected from the following list:

[0725]

[0726]

[0727]

[0728] wherein "Me" is methyl and "Et" is ethyl.

[0729] In a preferred embodiment, the LC medium comprises one or more compounds of formula IB having two polymerizable groups, which are preferably selected from formula IB-D

[0730]

[0731] wherein P and Sp have the meanings given in formula IB, L has one of the meanings given in formula IB, which is different from P-Sp-, r1, r2 and r3 are each independently 0, 1, 2, 3 or 4, preferably 0, 1 or 2, very preferably 0 or 1, and k is 0 or 1.

[0732] Preferred compounds of formula IB-D are selected from the following sub-formulas

[0733]

[0734] wherein P and Sp, L, r1, r2 and r3 each independently have one of the meanings given in formula IB-D or one of its preferred meanings given in the context.

[0735] Particularly preferred is the compound of formula IB-D-1.

[0736] In the compounds of formula IB-D, it is preferred that at least one of r1, r2 and r3 is not 0. P is preferably acrylate or methacrylate, very preferably methacrylate. It is preferred that all groups P in formulae IB-D, IB-D-1 and IB-D-2 have the same meaning, and very preferably represent methacrylate. Sp” is preferably selected from -(CH2)2-, -(CH2)3-, -(CH2)4-, -O-(CH2)2-, -O-(CH2)3-, -O-CO-(CH2)2 and -CO-O-(CH)2-, where the O atom or the CO group is attached to the benzene ring. L is preferably selected from F, CH3, OCH3, OC2H5 and C2H5, very preferably selected from F.

[0737] Very preferably, the compounds of formula IB-D are selected from the following sub-formulae:

[0738]

[0739]

[0740]

[0741]

[0742]

[0743]

[0744] Very preferably, the compounds of formula IBD1, IBD4, IBD6, IBD7, IBD19, IBD21 and IBD23.

[0745] Further preferably, the compounds of formulae IBD1 to IBD25, in which one or two methacrylate groups are replaced by acrylate groups.

[0746] Further preferably, the compounds of formula IB-D are selected from the following Table D, very preferably selected from RM-1, RM-2, RM-3, RM-7 to RM-49 and RM-58 to RM-77, very preferably selected from RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM-40, RM-41, RM-48, RM-58, RM-64, RM-72 and RM-74.

[0747] In another preferred embodiment, the LC medium comprises one or more polymerizable compounds of formula IB having three polymerizable groups, which are preferably selected from formula IB-T

[0748]

[0749] wherein P, Sp, L, r1, r2 and k independently of one another have one of the meanings given in formula IB-D or one of their preferred meanings given by the context, and r4 is 0, 1, 2 or 3, preferably 0, 1 or 2, very preferably 0 or 1.

[0750] Preferred compounds of formula IB-T are selected from the following sub-formulas

[0751]

[0752] wherein P, Sp, L, r1, r2 and r4 independently of one another have one of the meanings given in formula IB-T or one of their preferred meanings given by the context. Preferably at least one of r1, r2 and r4 is not 0. P is preferably acrylate or methacrylate, very preferably methacrylate. L is preferably selected from F, CH3, OCH3, OC2H5 and C2H5, very preferably selected from OCH3 or F. Preferably all groups P in formulas IB-T and IB-T-1 to IB-T-6 have the same meaning, and very preferably represent methacrylate.

[0753] Particularly preferred are the compounds of formula IB-T-1, IB-T-4 and IB-T-5. Very preferred compounds of formula IB-T are selected from the following sub-formulas:

[0754]

[0755]

[0756]

[0757]

[0758]

[0759]

[0760]

[0761]

[0762]

[0763]

[0764]

[0765]

[0766]

[0767]

[0768]

[0769]

[0770] Among the compounds of formulas IBT1 to IBT21 having two benzene rings, the compounds of formulas IBT1, IBT2, IBT3, IBT8, IBT9, IBT10, IBT15, IBT16, and IBT17 are highly preferred. The compounds of formulas IBT1, IBT2, IBT3, IBT8, IBT9, and IB10 are most preferred.

[0771] Among the compounds of formulas IBT22 to IBT53 having three benzene rings, the compounds of formulas IBT22 to IBT46 are highly preferred. The compounds of formulas IBT22, IBT28, IBT29, IBT35, and IBT36 are most preferred.

[0772] Further preferred are the compounds of formulas IBT1 to IBT53, in which one or two methacrylate groups are replaced by acrylate groups.

[0773] Further preferred are the compounds of formulas IBT1 to IBT53, in which all methacrylate groups are replaced by acrylate groups.

[0774] In another preferred embodiment, the LC medium comprises at least one compound of formula IC, which is at least monosubstituted by an alkenyl L b The preferred compounds of formula IC of this preferred embodiment are selected from the following sub-formulas:

[0775]

[0776]

[0777]

[0778] wherein P, Sp, L, r1, r2, r3, and r4 have the meanings given in formulas IB-D and IB-T or one of the preferred meanings given in the context, wherein r1 + r2 + r3 + r4 ≥ 1, and wherein the compound contains at least one group L b representing L.

[0779] Among the compounds of formulas IC-1 to IC-9, preferably L b represents -CH=CH2, -CH2-CH=CH2, -CH=CH-CH3, -CH=CH-CH=CH2, or -C(CH3)=CH2, and very preferably -CH=CH2 or -C(CH3)=CH2.

[0780] Among the compounds of formulas IC-1 to IC-9, P is preferably acrylate or methacrylate, and very preferably methacrylate. If Sp is different from a single bond, it is preferably selected from -(CH2)2-, -(CH2)3-, -(CH2)4-, -O-(CH2)2-, -O-(CH2)3-, -O-CO-(CH2)2 and -CO-O-(CH)2-, where the O atom or the CO group is connected to the benzene ring. L is preferably selected from F, CH3, OCH3, OC2H5 or C2H5, and very preferably selected from OCH3 or F. Preferably, all the groups P in formulas IC-1 to IC-9 have the same meaning, and very preferably represent methacrylate.

[0781] Very preferably, the compounds of formulas IC-1 to IC-9 are selected from the following sub-formulas:

[0782]

[0783]

[0784]

[0785]

[0786]

[0787]

[0788]

[0789] Further preferably, the compounds of formulas IC1 to IC46, in which one, two or all of the methacrylate groups are replaced by acrylate groups.

[0790] In a preferred embodiment, the LC medium comprises at least one polymerizable compound of formula IA and / or formula IB and / or formula IC having absorption in the range of 330 to 390 nm. Very preferably, these compounds have an extinction coefficient of at least 0.5 in the following wavelength ranges, in the range of 330 to 390 nm, more preferably in the range of 340 nm to 380 nm, very preferably in the range of 350 nm to 370 nm, and most preferably in the range of 355 to 365 nm. Unless otherwise specified, the extinction coefficient and absorption wavelength are measured in a solution of the compound in DCM at a concentration of 3 g / L.

[0791] According to the present invention, the total proportion of the polymerizable compounds of formula IA, IB, IC and their sub-formulas in the LC medium is preferably 0.05 to 3.0%, more preferably 0.1 to 1.5%, and very preferably 0.1 to 0.9%.

[0792] In a first preferred embodiment of the present invention, the LC medium contains one or more, preferably exactly one compound of formula IA or a sub-formula thereof and one or more, preferably exactly one compound of formula IB or IC or a sub-formula thereof, and preferably does not contain other polymerizable compounds.

[0793] Preferably, in the LC medium of this first preferred embodiment, the proportion of the compound of formula IA or a sub-formula thereof is 0.01 to 1.0%, more preferably 0.05 to 0.8%, very preferably 0.1 to 0.6%, and the proportion of the compound of formula IB or IC or a sub-formula thereof is 0.01 - 1.0%, more preferably 0.02 - 0.8%, very preferably 0.05 to 0.5%.

[0794] In a second preferred embodiment of the present invention, the LC medium contains one or more, preferably exactly one compound of formula IA or a sub-formula thereof, one or more, preferably exactly one compound of formula IB or a sub-formula thereof, and one or more, preferably exactly one compound of formula IC or a sub-formula thereof, and preferably does not contain other polymerizable compounds.

[0795] More preferably, the LC medium of this second preferred embodiment contains one or more, preferably exactly one compound of formula IA or a sub-formula thereof, one or more, preferably exactly one compound of formula IB-D or IB-T or a sub-formula thereof, and one or more, preferably exactly one compound selected from formula IC-1 to IC-9 or a sub-formula thereof, and preferably does not contain other polymerizable compounds.

[0796] Preferably, in the LC medium of this second preferred embodiment, the proportion of the compound of formula IA or a sub-formula thereof is 0.01 - 1.0%, more preferably 0.05 - 0.8%, very preferably 0.1 - 0.6%, the total proportion of the compounds of formula IB-D and IB-T or a sub-formula thereof is 0.01 - 1.0%, more preferably 0.05 - 0.8%, very preferably 0.1 - 0.6%, and the total proportion of the compounds of formula IC-1 to IC-9 or a sub-formula thereof is 0.01 to 1.0%, more preferably 0.02 to 0.8%, very preferably 0.05 to 0.5%.

[0797] In another preferred embodiment, in addition to the polymerizable compounds of formula IA, IB, IC and their sub-formulas, the LC medium further contains at least one other polymerizable compound.

[0798] The compounds of formula M and its sub-formulas can be prepared analogously to methods known to those skilled in the art and described in standard works of organic chemistry (for example in Houben-Weyl, Methoden der organischen Chemie (Methods of Organic Chemistry), Thieme-Verlag, Stuttgart).

[0799] For example, acrylates or methacrylates can be prepared by esterifying the corresponding alcohol with an acid derivative (such as (meth)acryloyl chloride or (meth)acrylic anhydride) in the presence of, for example, pyridine or triethylamine and 4-(N,N-dimethylamino)pyridine (DMAP). Alternatively, the ester can be prepared by esterifying the alcohol with (meth)acrylic acid in the presence of a dehydrating reagent, for example, by esterification according to Steglich with dicyclohexylcarbodiimide (DCC), N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) or N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and DMAP.

[0800] The invention also relates to an LC medium or an LC display as described above, in which polymerizable compounds, such as those of formula M and its sub-formulae, are present in polymerized form.

[0801] Optionally, one or more polymerization initiators are added to the LC medium. Suitable polymerization conditions as well as suitable types and amounts of initiators are known to those skilled in the art and are described in the literature. Suitable radical polymerizations are, for example, commercially available photoinitiators or (Ciba AG). If a polymerization initiator is used, its proportion is preferably from 0.001 to 5% by weight, particularly preferably from 0.001 to 1% by weight.

[0802] The polymerizable compounds according to the invention are also suitable for polymerization without an initiator, which has considerable advantages, such as lower material costs, and in particular less contamination of the LC medium by possible residual amounts of the initiator or its degradation products. Therefore, the polymerization can also be carried out without adding an initiator. In a preferred embodiment, the LC medium thus does not contain a polymerization initiator.

[0803] The LC medium may further comprise one or more stabilizers to prevent the RM from undergoing unwanted spontaneous polymerization, for example, during storage or transportation. Suitable types and amounts of stabilizers are known to those skilled in the art and are described in the literature. Particularly suitable are, for example, commercially available stabilizers from the series (Ciba AG), such as 1076. If stabilizers are used, their proportion based on the total amount of RM or polymerizable components (component A) is preferably from 10 - 50,000 ppm, particularly preferably from 50 - 5,000 ppm.

[0804] In a preferred embodiment, the LC medium contains one or more chiral dopants, preferably at a concentration of 0.01 to 1 wt%, very preferably 0.05 to 0.5 wt%. The chiral dopants are preferably selected from the compounds of Table C below, very preferably selected from R- or S-1011, R- or S-2011, R- or S-3011, R- or S-4011 and R- or S-5011.

[0805] In another preferred embodiment, the LC medium contains a racemate of one or more chiral dopants, the chiral dopants preferably being selected from the chiral dopants mentioned in the previous paragraph.

[0806] In another preferred embodiment of the present invention, the LC medium contains one or more additional stabilizers.

[0807] Preferred stabilizers are selected from the compounds of formula H

[0808]

[0809] wherein

[0810] Ar represents an aromatic or heteroaromatic hydrocarbon group having 4 to 40 C atoms, preferably 6 to 30 C atoms;

[0811] Sp represents a spacer group;

[0812] R S represents H, an alkyl group having 1 to 12 C atoms or an alkenyl group having 2 to 12 C atoms;

[0813] Z S represents -O-, -C(O)O-, -(CH2) z -, or -(CH2) z O-, or a single bond,

[0814] HA represents

[0815] R H represents H, O·, CH3, OH or OR S , preferably H or O·;

[0816] R S1 、R S2 、R S3 and R S4 are the same or different and represent an alkyl group having 1 to 6 C atoms, preferably having 1 to 3 C atoms, very preferably CH3;

[0817] G represents H or R S or the group Z S -HA;

[0818] z is an integer from 1 to 6; and

[0819] q is 3 or 4.

[0820] Compounds of formula H are described in EP3354710 A1 and EP3354709 A1.

[0821] Preferred compounds of formula H are selected from formulae H-1, H-2 and H-3:

[0822]

[0823] wherein R H has the meaning given above and preferably represents H or O·, and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7, and Sp represents a spacer group, preferably an alkylene group having 1 to 12 C atoms, wherein one or more non-adjacent -CH2- groups may be replaced by -O-.

[0824] Preferred compounds of formula H-1 are those of formula H-1-1:

[0825]

[0826] wherein R H has the meaning given above and preferably represents H or O·, and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0827] Very preferred compounds of formula H-1-1 are those of formula H-1-1-1:

[0828]

[0829] Preferred compounds of formula H-2 are those of formula H-2-1:

[0830]

[0831] wherein R H has the meaning given above and preferably represents H or O·, and n2 is, each time it occurs, the same or different, preferably the same, an integer from 1 to 12, preferably 2, 3, 4, 5 or 6, very preferably 3, and R S is, each time it occurs, the same or different, preferably the same, an alkyl group having 1 to 6 C atoms, preferably n-butyl.

[0832] Very preferred compounds of formula H-2-1 are those of formula H-2-1-1:

[0833]

[0834] The preferred compounds of formula H-3 are selected from formula H-3-1:

[0835]

[0836] where Sp and R H have the meanings given above, and R H preferably represents H or O·, and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0837] Further preferred stabilizers are selected from formulas ST-1 to ST-18:

[0838]

[0839]

[0840]

[0841] where

[0842] R ST represents H, an alkyl or alkoxy group having 1 to 15 C atoms, wherein furthermore one or more CH2 groups can each independently of one another be replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-,

[0843]

[0844] -O-, -CO-O-, -O-CO- in such a way that the O atoms are not directly linked to one another, and wherein furthermore one or more H atoms can be replaced by halogen,

[0845] represents, in each occurrence, the same or different

[0846]

[0847] Z ST each independently of one another represents -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-, -CH2O-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond,

[0848] L 1 and L 2 each independently of one another represents F, Cl, CH3, CF3 or CHF2,

[0849] p represents 0, 1 or 2,

[0850] q represents 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0851] Preferred compounds of formula ST are those selected from formula ST-3, and in particular:

[0852]

[0853] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3

[0854]

[0855] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3

[0856]

[0857] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 1 or 7

[0858]

[0859]

[0860] In the compounds of formula ST-3a and ST-3b, n preferably represents 3. In the compounds of formula ST-2a, n preferably represents 7.

[0861] Highly preferred stabilizers are selected from the compounds of formula ST-2a-1, ST-3a-1, ST-3b-1, ST-8-1, ST-9-1 and ST-12:

[0862]

[0863]

[0864] In another preferred embodiment, the LC medium comprises one or more stabilizers selected from Table D below.

[0865] Preferably, in the LC medium, the proportion of the stabilizer is 10 to 500 ppm, very preferably 20 to 100 ppm.

[0866] In another preferred embodiment, the LC medium according to the invention contains a self-aligning (SA) additive, preferably at a concentration of 0.1 to 2.5%.

[0867] In a preferred embodiment, the SA-VA display according to the present invention does not contain a polyimide alignment layer. In another preferred embodiment, the SA-VA display according to the preferred embodiment contains a polyimide alignment layer.

[0868] Preferred SA additives for use in this preferred embodiment are selected from compounds comprising a mesogenic group and a linear or branched alkyl side chain, said alkyl side chain being terminated with one or more polar anchoring groups selected from hydroxyl, carboxyl, amino or thiol groups.

[0869] Further preferred SA additives contain one or more polymerizable groups, which are optionally linked to the mesogenic group via a spacer group. These polymerizable SA additives can be polymerized in the LC medium under conditions similar to those applied to the RM during the PSA process.

[0870] Suitable SA additives for inducing vertical alignment, especially SA additives for use in SA-VA mode displays, are disclosed, for example, in US2013 / 0182202 A1, US 2014 / 0838581A1, US2015 / 0166890 A1 and US2015 / 0252265 A1.

[0871] In another preferred embodiment, the LC medium or polymer-stabilized SA-VA display according to the present invention contains one or more self-alignment additives selected from Table F below.

[0872] In another preferred embodiment, the LC medium according to the present invention contains one or more SA additives, which are preferably selected from formula II or its sub-formulas or from Table F below, in a concentration of 0.1 to 5%, very preferably 0.2 to 3%, and most preferably 0.2 to 1.5%.

[0873] The present invention further relates to an LC display comprising the LC medium according to the present invention as described above and below, which is preferably a PSA or SA display, very preferably a PS-VA, PS-IPS, PS-FFS or SA-VA display.

[0874] The present invention further relates to an LC display comprising the LC medium as described above and below, wherein the polymerizable compound is present in a polymerized form, and the LC display is preferably a PSA or SA display, very preferably a PS-VA, PS-IPS, PS-FFS or SA-VA display.

[0875] To prepare a PSA or polymer-stabilized SA display, the polymerizable compounds contained in the LC medium are polymerized in situ between the substrates of the LC display in the LC medium, preferably while applying a voltage to the electrodes.

[0876] The structure of the display according to the invention corresponds to the usual geometry of PSA displays, as described in the prior art cited at the beginning. A geometry without protrusions is preferred, in particular those shapes in which the electrodes on the color filter side are unstructured and only the electrodes on the TFT side have grooves. Particularly suitable and preferred electrode structures for PS-VA displays are described, for example, in US2006 / 0066793 A1.

[0877] The preferred PSA type LC display of the invention comprises:

[0878] - 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 micro-slit patterns, and optionally a first alignment layer provided on the pixel electrodes,

[0879] - A second substrate comprising a common electrode layer which can be provided on the entire part of the second substrate facing the first substrate and optionally a second alignment layer,

[0880] - An LC layer provided between the first and second substrates and comprising an LC medium as described above and below, wherein the polymerizable compounds can also be present in polymerized form.

[0881] The first and / or second alignment layer controls the alignment direction of the LC molecules of the LC layer. For example, in a PS-VA display, the alignment layer is selected such that it imparts a homeotropic (or perpendicular) alignment (i.e., perpendicular to the surface) or an inclined alignment to the LC molecules. Such an alignment layer can, for example, comprise polyimide, which can also be rubbed, or can be prepared by a photo-alignment method.

[0882] The LC layer with the LC medium can be deposited between the substrates of the display by methods commonly used by display manufacturers, such as the so-called drop-down filling (ODF) method. Then the polymerizable components of the LC medium are polymerized, for example, by UV photopolymerization. The polymerization can be carried out in one step or in two or more steps.

[0883] The PSA display can include additional elements, such as color filters, black matrices, passivation layers, optical retardation layers, transistor elements for addressing individual pixels, etc., all of which are well known to those skilled in the art and can be used without creative skills.

[0884] Those skilled in the art can design the electrode structure according to the individual display type. For example, for a PS-VA display, the multi-domain alignment of the LC molecules can be induced by providing electrodes having slits and / or bumps or protrusions to create two, four or more different tilt alignment directions.

[0885] When polymerized, the polymerizable compound forms a copolymer, which results in a specific tilt angle of the LC molecules in the LC medium. Without wishing to be bound by a particular theory, it is believed that at least a portion of the cross-linked polymer formed from the polymerizable compound will phase separate or precipitate from the LC medium and form a polymer layer on the substrate or electrode, or on the alignment layer provided thereon. Microscopic measurement data (such as SEM and AFM) have confirmed that at least a portion of the polymer formed accumulates at the LC / substrate interface.

[0886] The polymerization can be carried out in one step. It is also possible to first carry out the polymerization in a first step, optionally while applying a voltage, to generate a tilt angle, and subsequently, in a second polymerization step, polymerize or crosslink the compounds that have not reacted in the first step ("final curing") without applying a voltage.

[0887] Suitable and preferred polymerization methods are, for example, thermal polymerization or photopolymerization, preferably photopolymerization, especially UV-induced photopolymerization, which can be achieved by exposing the polymerizable compound to UV radiation.

[0888] The polymerizable compounds of formula M and its sub-formulas indeed show particularly good UV absorption in the method for preparing a PSA display, and are therefore particularly suitable for the method for preparing a PSA display, which method for preparing a PSA display comprises one or more of the following features or any combination thereof:

[0889] - The polymerizable medium is exposed to UV light in a two-step method in the display, which two-step method comprises a first UV exposure step ("UV1 step") with a voltage applied to the electrodes of the display to generate a tilt angle, and a second UV exposure step ("UV2 step") without applying a voltage to the electrodes of the display to complete the polymerization of the polymerizable compound,

[0890] - The polymerizable medium is exposed to UV light generated by a UV-LED lamp in the display, preferably at least in the UV2 step, more preferably in both the UV1 and UV2 steps,

[0891] - Exposing the polymerizable medium in the display to UV light generated by energy-saving UV lamps (also known as "green UV lamps"). These lamps are characterized by relatively low intensity in their absorption spectrum of 300 - 380 nm (1 / 100 - 1 / 10 of conventional UV1 lamps), and are preferably used in the UV2 step, but are also optionally used in the UV1 step when the method requires avoiding high intensity.

[0892] - Exposing the polymerizable medium in the display to UV light generated by a UV lamp, the radiation spectrum of which is shifted to longer wavelengths, preferably ≥ 340 nm, more preferably 350 to < 370 nm, very preferably 355 to 368 nm, to avoid short-term UV light exposure in the PS-VA method.

[0893] Using lower intensity and a UV shift to longer wavelengths can both protect the organic layer from damage that may be caused by UV light.

[0894] A preferred embodiment of the present invention relates to a method for preparing a PSA display as described above and below, the method comprising one or more of the following features or any combination thereof:

[0895] - Irradiating the polymerizable LC medium with UV light in a two-step method, the two-step method comprising a first UV exposure step ("UV1 step") with voltage applied to generate an inclination angle, and a second UV exposure step ("UV2 step") without voltage applied to complete the polymerization of the polymerizable compound.

[0896] - Irradiating the polymerizable LC medium with UV light generated by a UV lamp, the intensity of the UV light being 0.5 mW / cm 2 to 10 mW / cm 2 and the wavelength range being 300 - 380 nm, preferably in the UV2 step, and optionally also in the UV1 step.

[0897] - Irradiating the polymerizable LC medium with UV light having a wavelength of ≥ 340 nm, and preferably ≤ 420 nm, very preferably in the range of 340 to 380 nm, more preferably in the range of 350 to < 370 nm, and most preferably in the range of 355 to 368 nm.

[0898] - Irradiating the polymerizable LC medium with UV light while applying voltage to the electrodes of the display.

[0899] - Using UV-LED lamps for UV light irradiation.

[0900] For example, this preferred method can be implemented by using a desired UV lamp or by using a band-pass filter and / or a cut-off filter that are substantially transmissive to UV light having one or more corresponding desired wavelengths and substantially block light having corresponding unwanted wavelengths. For example, when irradiation with UV light having a wavelength λ of 300 - 400 nm is required, UV exposure can be implemented using a broadband-pass filter that is substantially transmissive to wavelengths of 300 nm < λ < 400 nm. When irradiation with UV light having a wavelength λ of more than 340 nm is required, UV irradiation can be implemented using a cut-off filter that is substantially transmissive to a wavelength λ of > 340 nm.

[0901] In a preferred embodiment of the present invention, UV irradiation is implemented using a UV-LED lamp.

[0902] In the PSA method, using a UV-LED lamp having only one narrow emission peak provides several advantages. For example, depending on the selection of a suitable polymerizable compound (which exhibits absorption at the emission wavelength of the LED lamp), light energy can be more effectively transferred to the polymerizable compound in the LC medium. This allows for a reduction in UV intensity and / or UV irradiation time, thus enabling a reduced operation time and savings in energy and production costs. Another advantage is that the narrow emission spectrum of the lamp allows for an easier selection of a suitable wavelength for photopolymerization.

[0903] Very preferably, the UV light source is a UV-LED lamp that emits wavelengths in the range of 340 to 400 nm, more preferably in the range of 340 to 380 nm. A UV-LED lamp that emits UV light having a wavelength of 365 nm is particularly preferred.

[0904] Preferably, the UV-LED lamp emits light having an emission peak with a full width at half maximum (FWHM) of 30 nm or less.

[0905] UV-LED lamps are commercially available from, for example, Dr. Hoenle AG in Germany or Primelite GmbH in Germany or IST Metz GmbH in Germany, which emit wavelengths such as 365, 385, 395, and 405 nm.

[0906] This preferred method enables the manufacture of displays by using longer UV wavelengths, thereby reducing or even avoiding the harmful and destructive effects of short UV light components.

[0907] The UV radiation energy is generally 6 to 100 J, depending on the preparation method conditions.

[0908] The LC medium according to the invention may additionally comprise one or more further components or additives, which are preferably selected from the substances listed below, including but not limited to: comonomers, chiral dopants, polymerization initiators, inhibitors, stabilizers, surfactants, wetting agents, lubricants, dispersants, water repellents, binders, flow improvers, defoamers, degassing agents, diluents, reactive diluents, auxiliaries, colorants, dyes, pigments and nanoparticles.

[0909] Furthermore, for example, 0 to 15% by weight of a dichroic dye can be added to the LC medium, and furthermore nanoparticles, a conductive salt, preferably a complex salt of ethyl dimethyldodecyl 4-hexyloxybenzoate, tetrabutyltetraphenylborate or a crown ether (see, for example, Haller et al., Mol. Cryst. Liq. Cryst. 24 , 249-258 (1973)) can be used to improve the 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 2209 127, 2240 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 2853 728.

[0910] The individual components of the above-listed preferred embodiments of the LC medium according to the invention are known, or the methods for preparing them can be obtained by the person skilled in the art from the prior art, since they are based on standard methods described in the literature. For example, the corresponding compounds of formula CY are described in EP-A-0 364538. The corresponding compounds of formula ZK are described, for example, in DE-A-26 36 684 and DE-A-3321 373.

[0911] The LC medium that can be used according to the invention is prepared in a conventional manner per se, for example by mixing one or more of the above-mentioned compounds with one or more polymerizable compounds as defined above, and optionally with other liquid crystal compounds and / or additives. Usually, the desired amounts of the components used in smaller amounts are dissolved in the components that make up the main components, which is advantageously carried out at an elevated temperature. The solutions of the components can also be mixed in an organic solvent such as acetone, chloroform or methanol, and the solvent is removed again, for example by distillation after thorough mixing. The invention also relates to a method for preparing the LC medium according to the invention.

[0912] It goes without saying for the person skilled in the art that the LC medium according to the invention can also comprise, for example, compounds in which H, N, O, Cl, F are replaced by the corresponding isotopes such as deuterium.

[0913] The following examples illustrate the present invention but do not limit the present invention. However, they show preferred mixture concepts to those skilled in the art, as well as the compounds preferably used and their respective concentrations, and their combinations with each other. In addition, the examples illustrate which properties and combinations of properties are obtainable.

[0914] For the present invention and in the following examples, the structures of the liquid-crystal compounds are indicated with the aid of acronyms. Unless otherwise indicated, the conversion into chemical formulae is carried out according to the following Tables A.1 to A.3. All radicals C n H 2n+1 , C m H 2m+1 and C l H 2l+1 or C n H 2n , C m H 2m and C l H 2l is a straight-chain alkyl group or alkylene group having n, m and 1 C atoms, respectively, in each case. Preferably, n, m and 1 are independently 1, 2, 3, 4, 5, 6 or 7. Table A.1 shows the ring element codes of the core structure of the compounds, Table A.2 lists the bridging units, and Table A.3 lists the meanings of the symbols of the left-hand and right-hand end groups of the molecules. The acronyms consist of the code for the ring element with the optional linking group, followed by a first hyphen, and the code for the left-hand end group, and a second hyphen and the code for the right-hand end group.

[0915] Table A.1: Ring elements

[0916]

[0917]

[0918]

[0919]

[0920] Table A.2: Bridging units

[0921]

[0922] Table A.3: End groups

[0923]

[0924]

[0925]

[0926]

[0927] Wherein n and m are each integers, and the three dots "…" are placeholders for other abbreviations from the table.

[0928] Table B shows the schematic structures of the compounds and their corresponding abbreviations.

[0929] Table B

[0930] In Table B, n, m, k, and l are each independently integers, preferably from 1 to 9, more preferably from 1 to 7, k and l can also be 0, preferably from 0 to 4, more preferably 0 or 2, most preferably 2, n is preferably 1, 2, 3, 4, or 5, in the combination "-nO-", n is preferably 1, 2, 3, or 4, very preferably 2 or 4, m is preferably 1, 2, 3, 4, or 5, in the combination "-Om", m is preferably 1, 2, 3, or 4, more preferably 2 or 4. The combination "-nVm" is preferably "2V1". (O)C m H 2m+1 means C m H 2m+1 or OC m H 2m+1 .

[0931]

[0932]

[0933]

[0934]

[0935]

[0936]

[0937]

[0938]

[0939]

[0940]

[0941]

[0942]

[0943]

[0944]

[0945]

[0946]

[0947]

[0948]

[0949]

[0950]

[0951]

[0952]

[0953]

[0954] In a preferred embodiment of the present invention, the LC medium according to the present invention comprises one or more compounds selected from the compounds of Table B.

[0955] Table C

[0956] Table C shows the possible chiral dopants that can be added to the LC medium according to the present invention.

[0957]

[0958]

[0959] The LC medium preferably comprises 0 to 10 wt%, particularly 0.01 to 5 wt%, and especially preferably 0.1 to 3 wt% of the dopant. The LC medium preferably comprises one or more dopants selected from the compounds of Table C.

[0960] Table D

[0961] Table D shows the possible stabilizers that can be added to the LC medium according to the present invention. Wherein n represents an integer from 1 to 12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, and the terminal methyl groups are not shown.

[0962]

[0963]

[0964]

[0965]

[0966]

[0967]

[0968] The LC medium preferably contains 0 to 10 wt%, especially 1 ppm to 5 wt%, and particularly preferably 1 ppm to 1 wt% of a stabilizer. The LC medium preferably contains one or more stabilizers selected from the compounds shown in Table D.

[0969] Table E

[0970] Table E shows exemplary reactive mesogenic compounds that can be used in the LC medium according to the present invention.

[0971]

[0972]

[0973]

[0974]

[0975]

[0976]

[0977]

[0978]

[0979]

[0980]

[0981]

[0982]

[0983]

[0984]

[0985]

[0986]

[0987]

[0988]

[0989]

[0990] In a preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds, preferably selected from the polymerizable compounds of the formulae RM-1 to RM-182. 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-58, RM-64, RM-74, RM-76, RM-88, RM-91, RM-102, RM-103, RM-109, RM-116, RM-117, RM-120, RM-121, RM-122, RM-139, RM-140, RM-142, RM-143, RM-145, RM-146, RM-147, RM-149, RM-156 to RM-163, RM-169, RM-170 and RM-171 to RM-183 are particularly preferred.

[0991] Table F

[0992] Table F shows the self-aligning compounds for vertical alignment, which can be used together with the polymerizable compounds in the LC medium for SA-VA and SA-FFS displays according to the invention:

[0993]

[0994]

[0995]

[0996]

[0997]

[0998]

[0999]

[1000]

[1001]

[1002]

[1003]

[1004] In a preferred embodiment, the LC media, SA-VA and SA-FFS displays according to the invention comprise a combination of one or more SA additives and one or more RMs, said SA additives being selected from formulas SA-1 to SA-48, preferably from formulas SA-14 to SA-48, very preferably from formulas SA-20 to SA-34 and SA-44. Detailed Description

[1005] Examples

[1006] The following examples illustrate the invention without limiting it. However, they show the skilled person the concept of the 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.

[1007] Additionally, the following abbreviations and symbols are used:

[1008] V0 represents the threshold voltage at 20 °C, capacitive [V],

[1009] n e represents the extraordinary refractive index at 20 °C and 589 nm,

[1010] n o represents the ordinary refractive index at 20 °C and 589 nm,

[1011] Δn represents the optical anisotropy at 20 °C and 589 nm,

[1012] ε ⊥ represents the dielectric constant perpendicular to the director at 20 °C and 1 kHz,

[1013] ε || represents the dielectric constant parallel to the director at 20 °C and 1 kHz,

[1014] Δε represents the dielectric anisotropy at 20 °C and 1 kHz,

[1015] cl.p., T(N,I) represents the clearing point [°C],

[1016] γ1 represents the rotational viscosity at 20 °C [mPa·s],

[1017] K1 represents the elastic constant at 20 °C, "splay" deformation [pN],

[1018] K2 represents the elastic constant at 20 °C, "twist" deformation [pN],

[1019] K3 represents the elastic constant at 20 °C, "bend" deformation [pN],

[1020] K平均 Denotes the average elastic constant [pN] at 20 °C, which is defined as K in this article 平均 ≡( 3 / 2K1 + K3) / 3 ≈ (K1 + K2 + K3) / 3,

[1021] LTS denotes the low-temperature stability of the phase, which is determined in a test cell

[1022] VHR denotes the voltage holding ratio

[1023] Unless otherwise expressly stated, all concentrations in this application are given as weight percentages and relate to the corresponding entire mixture, which includes all solid or liquid crystal components (without solvent).

[1024] Unless otherwise noted, 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, and cl.p. = the clearing point. In addition, C = liquid crystal phase, N = nematic phase, S = smectic phase, and I = isotropic phase. The data between these symbols represent the transition temperatures.

[1025] 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 expressly stated otherwise in each case.

[1026] The term "threshold voltage" used in the present invention relates to the capacitive threshold (V0), 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 )

[1027] Unless otherwise stated, the method of polymerizing the polymerizable compound in the 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.

[1028] Unless otherwise stated, the method of preparing the test cells and measuring their electro-optical and other properties is carried out by the method described below or a method similar thereto.

[1029] Unless otherwise stated, the PSVA display or PSVA test cell for photopolymerization and measurement of tilt angle, etc. consists of two plane-parallel glass outer plates spaced 3 - 4 μm apart, each of the glass outer plates having an electrode layer on the inner side and a polyimide alignment layer on the top, wherein the two polyimide layers are rubbed antiparallel to each other, resulting in a homeotropic edge alignment of liquid crystal molecules. The SAVA display or test cell has the same structure, but one or two polyimide layers are omitted therein.

[1030] The polymerizable compound is polymerized in the display or test cell by irradiating with UV light of a defined intensity for a predefined time while applying a voltage (usually 10V to 30V alternating current, 1kHz) to the display.

[1031] The tilt angle is measured using the Mueller Matrix Polarimeter “AxoScan” from Axometrics. Here, a low value (i.e., a large deviation from the 90° angle) corresponds to a large tilt.

[1032] Unless otherwise stated, 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 a uniform orientation, which corresponds to their molecular long axis in the case of rod-like (calamitic) uniaxial positive birefringent LC molecules.

[1033] Comparative Example 1

[1034] The nematic LC host mixture NC1 is formulated as follows:

[1035]

[1036] Mixture NC1 does not contain compounds of formula L1 or L2.

[1037] The chiral nematic LC host mixture CCh1 is formulated by adding 0.91% of the chiral dopant S - 4011 to 99.09% of the host mixture NC1.

[1038] The polymerizable LC mixture PC1 is formulated as follows:

[1039]

[1040]

[1041]

[1042] Comparative Example 2

[1043] The nematic LC host mixture NC2 is formulated as follows:

[1044]

[1045] The mixture NC2 does not contain compounds of formula L1 or L2.

[1046] The chiral nematic LC host mixture CCh2 is formulated by adding 0.89% of the chiral dopant S-4011 to 99.11% of the host mixture NC2.

[1047] The polymerizable LC mixture PC2 is formulated as follows:

[1048]

[1049]

[1050] Example 1

[1051] The nematic LC host mixture N1 is formulated as follows:

[1052]

[1053] The mixture N1 contains the compound CLP-3-T of formula L1.

[1054] The chiral nematic LC host mixture Ch1 is formulated by adding 0.9% of the chiral dopant S-4011 to 99.1% of the host mixture N1.

[1055] The polymerizable LC mixture P1 is formulated as follows:

[1056]

[1057]

[1058] Example 2

[1059] The nematic LC host mixture N2 is formulated as follows:

[1060]

[1061] The mixture N2 contains the compound CLP-V-1 of formula L2.

[1062] The chiral nematic LC host mixture Ch2 is formulated by adding 0.9% of the chiral dopant S-4011 to 99.1% of the host mixture N2.

[1063] The polymerizable LC mixture P2 is formulated as follows:

[1064]

[1065]

[1066] After the PSA process and after aging, the VHRs of the polymerizable mixtures of Examples 1 and 2 and of Examples 1 and 2 were measured and compared. The physical properties and VHRs of the polymerizable mixtures are summarized in Table 1 below.

[1067] Table 1 - Physical Properties and VHR

[1068]

[1069] It can be seen that the VHRs of the polymerizable mixtures P1 and P2 according to the invention containing the compounds of formula L1 or L2 are significantly better than those of the polymerizable mixtures PC1 and PC2 which do not contain these compounds, while maintaining the expected values of other key properties such as dielectric anisotropy, birefringence, low viscosity and low γ1 / K 11 value.

[1070] Example 3

[1071] The nematic LC host mixture N3 was prepared as follows:

[1072]

[1073]

[1074] Mixture N3 contains the compound CLP-V-1 of formula L2. The polymerizable LC mixture P3 was prepared as follows:

[1075]

[1076]

[1077] Example 4

[1078] The nematic LC host mixture N4 was prepared as follows:

[1079]

[1080] Mixture N4 contains the compound CLP-V-1 of formula L2.

[1081] The polymerizable LC mixture P4 was prepared as follows:

[1082]

[1083] Example 5

[1084] The nematic LC host mixture N5 is formulated as follows:

[1085]

[1086] Mixture N5 contains the compound CLP-V-1 of formula L2.

[1087] The polymerizable LC mixture P5 is formulated as follows:

[1088]

[1089] Example 6

[1090] The polymerizable LC mixture P6 is formulated as follows:

[1091]

[1092]

[1093] Example 7

[1094] The polymerizable LC mixture P7 is formulated as follows:

[1095]

[1096]

[1097] Example 8

[1098] The polymerizable LC mixture P8 is formulated as follows:

[1099]

[1100]

[1101] Example 9

[1102] The polymerizable LC mixture P9 is formulated as follows:

[1103]

[1104] Example 10

[1105] The polymerizable LC mixture P10 is formulated as follows:

[1106]

[1107] Example 11

[1108] The polymerizable LC mixture P11 is formulated as follows:

[1109]

[1110]

[1111] Example 12

[1112] The polymerizable LC mixture P12 is prepared as follows:

[1113]

[1114]

[1115] Example 13

[1116] The polymerizable LC mixture P13 is prepared as follows:

[1117]

[1118]

[1119] Example 14

[1120] The polymerizable LC mixture P14 is prepared as follows:

[1121]

[1122] Example 15

[1123] The polymerizable LC mixture P15 is prepared as follows:

[1124]

[1125] Example 16

[1126] The polymerizable LC mixture P15 is prepared as follows:

[1127]

[1128]

[1129] Example 17

[1130] The polymerizable LC mixture P17 is prepared as follows:

[1131]

[1132] Example 18

[1133] The polymerizable LC mixture P18 is prepared as follows:

[1134]

[1135] Example 19

[1136] The polymerizable LC mixture P19 is prepared as follows:

[1137]

[1138]

[1139] Example 20

[1140] The polymerizable LC mixture P20 is prepared as follows:

[1141]

[1142]

[1143] Example 21

[1144] The polymerizable LC mixture P21 is prepared as follows:

[1145]

[1146]

[1147]

[1148] Example 22

[1149] The polymerizable LC mixture P22 is prepared as follows:

[1150]

[1151] Example 23

[1152] The polymerizable LC mixture P23 is prepared as follows:

[1153]

[1154] Example 24

[1155] The polymerizable LC mixture P24 is prepared as follows:

[1156]

[1157] Example 25

[1158] The polymerizable LC mixture P25 is prepared as follows:

[1159]

[1160] Example 26

[1161] The polymerizable LC mixture P26 is prepared as follows:

[1162]

[1163] Example 27

[1164] The polymerizable LC mixture P27 is prepared as follows:

[1165]

[1166] Example 28

[1167] The polymerizable LC mixture P28 is prepared as follows:

[1168]

[1169] Example 29

[1170] The polymerizable LC mixture P29 is prepared as follows:

[1171]

[1172]

[1173] Example 30

[1174] The polymerizable LC mixture P30 is prepared as follows:

[1175]

[1176] Example 31

[1177] The polymerizable LC mixture P31 is prepared as follows:

[1178]

[1179] Example 32

[1180] The polymerizable LC mixture P32 is prepared as follows:

[1181]

[1182]

[1183] Example 33

[1184] The polymerizable LC mixture P33 is prepared as follows:

[1185]

[1186]

[1187] Example 34

[1188] The polymerizable LC mixture P34 is prepared as follows:

[1189]

[1190]

[1191] Example 35

[1192] The polymerizable LC mixture P35 is prepared as follows:

[1193]

[1194]

[1195] Example 36

[1196] The polymerizable LC mixture P36 is prepared as follows:

[1197]

[1198]

[1199] Example 37

[1200] The polymerizable LC mixture P37 is prepared as follows:

[1201]

[1202]

[1203] Example 38

[1204] The polymerizable LC mixture P38 is prepared as follows:

[1205]

[1206]

[1207] Example 39

[1208] The polymerizable LC mixture P39 is prepared as follows:

[1209]

[1210]

[1211] Example 40

[1212] The polymerizable LC mixture P40 is prepared as follows:

[1213]

[1214]

[1215] Example 41

[1216] The polymerizable LC mixture P41 is prepared as follows:

[1217]

[1218] Example 42

[1219] The polymerizable LC mixture P42 is prepared as follows:

[1220]

[1221]

[1222] Example 43

[1223] The nematic LC host mixture N6 is prepared as follows:

[1224]

[1225] Mixture N6 contains the compound CLG-3-F of formula L1.

[1226] The polymerizable LC mixture P43 is prepared as follows:

[1227]

[1228] Example 44

[1229] The polymerizable LC mixture P44 is prepared as follows:

[1230]

[1231] Example 45

[1232] The polymerizable LC mixture P45 is prepared as follows:

[1233]

[1234] Example 46

[1235] The polymerizable LC mixture P46 is formulated as follows:

[1236]

[1237] Example 47

[1238] The polymerizable LC mixture P47 is formulated as follows:

[1239]

[1240] Example 48

[1241] The polymerizable LC mixture P48 is formulated as follows:

[1242]

[1243] Example 49

[1244] The polymerizable LC mixture P49 is formulated as follows:

[1245]

Claims

1. LC medium having negative dielectric anisotropy and comprising one or more compounds selected from the group consisting of formulae L1 and L2 and further comprising two or more polymerizable compounds, preferably compounds of formula M: R a -B 1 -(Z m -B 2 ) m -R b M The individual radicals have the following meanings independently of one another and identically or differently on each occurrence: R L1 is a straight-chain, branched or cyclic alkyl radical having 1 to 15 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CR 0 =CR 00 -,-C≡C-, substituted in such a way that the O- and / or S-atoms are not directly connected to one another, and wherein one or more H atoms are each optionally replaced by F or Cl, preferably alkyl or alkoxy having 1 to 6 C atoms, R L2 is a straight chain alkenyl group having 2 to 6 carbon atoms, preferably selected from CH2=CH-, CH2=CHCH2-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- and CH3-CH=CH-(CH2)2-, X L is F, Cl, CF3 or CHF2, preferably F or CF3, very preferably CF3, Y L is H, F, Cl or CH3, preferably H, Y is H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, very preferably H, P is a polymerizable group, Sp is a spacer group or a single bond, which is optionally replaced by L a replace, R a , R b is P, P-Sp-, H, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, SF5 or a straight-chain or branched alkyl radical having 1 to 25 C atoms, wherein in addition one or more non-adjacent CH2 groups may also be each independently replaced by -C(R 0 )=C(R 00 )-,-C≡C-,-N(R 00 )-, -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 one another, and in which one or more H atoms may also be replaced by F, Cl, Br, I, CN, P or P-Sp-, in which case if B 1 and / or B 2 Contains saturated C atoms, then R a and / or R b It can also represent the group connected to this saturated C atom spiro, The group R a and R b At least one of them represents or contains a group P or P-Sp-, P is a polymerizable group, Sp is a spacer group or a single bond, B 1 , B 2 is an aromatic, heteroaromatic, alicyclic or heterocyclic radical, which preferably has 4 to 25 ring atoms, said radical may also contain fused rings, and said radical is unsubstituted or mono- or polysubstituted by L, Z m is -O-, -S-, -CO-, -CO-O-, -OCO-, -O-CO-O-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -(CH2) n1 -, -CF2CH2-, -CH2CF2-, -(CF2) n1 -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, -CH2CH2-CO-O-, O-CO-CH2-CH2-, -CR 0 R 00 - or a single bond R 0 , R 00 is H or an alkyl radical having 1 to 12 C atoms, m is 0, 1, 2, 3 or 4, n1 is 1, 2, 3 or 4, L is P, P-Sp-, OH, CH2OH, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x )2, -C(=O)Y 1 , -C(=O)R x , -N(R x )2, optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, wherein one or more H atoms may also be replaced by F, Cl, P or P-Sp-, Y 1 For halogen, R x is P, P-Sp-, H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein in addition one or more non-adjacent CH2 groups can also be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and / or S atoms are not directly connected to one another, and in which in addition one or more H atoms can also be replaced by F, Cl, P or P-Sp-, optionally substituted aryl or aryloxy groups having 6 to 40 C atoms, or optionally substituted heteroaryl or heteroaryloxy groups having 2 to 40 C atoms.

2. LC medium according to claim 1, characterized in that The compound of formula L1 is selected from the following sub-formulae: Where R L1 has the meaning given in claim 1, preferably denotes alkyl having 1 to 6 C atoms, wherein the CH2 group is optionally replaced by cyclopropane-1,2-diyl or cyclopentane-1,2-diyl, very preferably propyl, pentyl, cyclopropyl, cyclopentyl, cyclopropylmethyl or cyclopentylmethyl, most preferably propyl or pentyl.

3. LC medium according to claim 1 or 2, characterized in that The compound of formula L2 is selected from the following sub-formulae: Here, "alkyl" refers to straight-chain alkyl radicals having 1 to 6 C atoms, wherein the CH2 radical may be replaced by cyclopropane-1,2-diyl or cyclopentane-1,2-dialkyl, and preferably denotes methyl, ethyl or propyl.

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

5. LC medium according to any one of claims 1 to 4, characterized in that It additionally comprises one or more compounds of formula III in R 31 and R 32 each independently of one another represents H, alkyl, alkoxy or alkenyl having up to 15 C atoms, which is unsubstituted, monosubstituted by F, Cl, CN or CF3 or at least monosubstituted by halogen, wherein in addition one or more CH2 groups in these radicals may be replaced by -O-, -S-, -S-, -S- or -S- in such a way that the O atoms are not directly connected to one another. -C≡C-, -CF2O-, -OCF2-, -OC-O- or -O-CO-, Y 1 , Y 2 is H, F, Cl, CF3, CHF2, CH3 or OCH3, preferably H, CH3 or OCH3, very preferably H, A 3 Each occurrence represents independently of each other a) 1,4-cyclohexenyl or 1,4-cyclohexylene, in which one or two non-adjacent CH2 groups may be replaced by -O- or -S-, b) 1,4-phenylene, in which one or both CH groups may be replaced by N, or c) a radical selected from the group consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octane-2,6-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, wherein the groups a), b) and c) may be substituted singly or polysubstituted by halogen atoms, n represents 0, 1 or 2, preferably 0 or 1, Z 1 Each occurrence independently represents -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-CH2O-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond, and L 11 and L 12 each independently of one another represents F, Cl, CF3 or CHF2, preferably H or F, most preferably F, and W represents O or S.

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

7. LC medium according to one or more of claims 1 to 6, characterized in that It comprises two or more compounds of formula M selected from the following formulae: where the individual radicals, identically or differently on each occurrence and independently of one another, have the following meanings: P 1 , P 2 , P 3 is a polymerizable group which is preferably selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy, very preferably acrylate or methacrylate, Sp 1 、Sp 2 、Sp 3 is a single bond or a spacer group, wherein in addition one or more groups P 1 -Sp 1 -、P 2 -Sp 2 - and P 3 -Sp 3 - can also represent R M , with the additional condition that the group P 1 -Sp 1 -、P 2 -Sp 2 and P 3 -Sp 3 -At least one of them is not R M , which preferably has one of the preferred meanings of Sp as given above, very preferably -(CH2) p1 -、-(CH2) p1 -O-, -(CH2) p1 -CO-O- or -(CH2) p1 -O-CO-O-, wherein p1 is an integer from 1 to 12, R M is H, F, Cl, CN or a straight-chain or branched alkyl radical having 1 to 25 C atoms, wherein in addition one or more non-adjacent CH2 groups may also be each independently replaced by -C(R 0 )=C(R 00 )-、-C≡C-、-N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, with O and / or S atoms not being directly connected to one another, and wherein one or more H atoms may also be replaced by F, Cl, CN or P 1 -Sp 1 - is substituted, particularly preferably, by a linear or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy radical having 1 to 12 C atoms, wherein the alkenyl and alkynyl radicals have at least two C atoms and the branched radicals have at least three C atoms, and wherein R M Does not represent or contain group P 1 , P 2 or P 3 , R 0 , R 00 is H or an alkyl radical having 1 to 12 C atoms, R y , R z is H, F, CH3 or CF3, X 1 , X 2 , X 3 is -CO-O-, -O-CO- or a single bond, Z M1 -O-, -CO-, -C(R y R z )- or -CF2CF2-, Z M2 , Z M3 -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -(CH2) n -, where n is 2, 3, or 4, L is F, Cl, CN or linear or branched, optionally mono- or polyfluorinated, alkyl, alkoxy, thioalkyl, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, L', L" are H, F or Cl, k is 0 or 1, 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.

8. LC medium according to one or more of claims 1 to 7, characterized in that It comprises two or more polymerizable compounds of formula M selected from formulae IA, IB and IC: P-Sp-M 1 -Sp-P IA P-Sp-M 2 -Sp-P IB P-Sp-M 3 -Sp-P IC wherein the individual radicals are identical or different at each occurrence and each independently have the following meanings: M 1 , M 2 , M 3 are groups each independently selected from the following formulae: wherein the benzene ring is optionally substituted by one or more groups L or P-Sp-, L is L a , L b , F, Cl, -CN, P-Sp-, or a straight-chain, branched or cyclic alkyl group having 1 to 25 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O- and / or S-atoms are not directly connected to one another, and wherein one or more H atoms are each optionally replaced by P, F or Cl, L a -C(R aa )(R bb )OH, R aa , R bb is a straight chain alkyl group having 1 to 6 C atoms, or optionally R aa and R bb together with the C atoms to which they are attached, form a cyclic alkyl radical having 3 to 12 C atoms, very preferably cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl, L b is a straight-chain or branched alkenyl group having 2 to 7 C atoms, preferably 3 or 4 C atoms, Wherein in the compound of formula IA, the group M 1 and / or at least one spacer group Sp is replaced by L a At least single substitution, and wherein in the compound of formula IC, the group M 3 At least by L b Single substitution.

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

10. Process for the preparation of an LC medium according to one or more of claims 1 to 9, comprising the following steps: One or more compounds of the formula L1 and / or L2 as defined in one or more of claims 1, 2, 3, 7 and 8 and two or more polymerizable compounds of the formula M are mixed with one or more compounds of the formula II, III, IV and / or V as defined in one or more of claims 4, 5 and 6, and optionally with other liquid crystal compounds and / or additives, and the polymerizable compounds are optionally polymerized.

11. LC display comprising an LC medium as defined in one or more of claims 1 to 9.

12. LC display according to claim 11, which is a PS-VA, PS-IPS, PS-FFS, PS-UB-FFS or SA-VA display.

13. An LC display according to claim 11 or 12, characterised in that It comprises two substrates, at least one of which is transparent to light, one electrode arranged on each substrate, or two electrodes arranged on only one substrate, and a layer of an LC medium according to one or more of claims 1 to 9 located between the substrates, wherein the polymerizable compound is polymerized between the substrates of the display by UV light polymerization.

14. A method of manufacturing an LC display according to claim 13, comprising the steps of: An LC medium according to one or more of claims 1 to 9 is provided between substrates of a display and the polymerisable compounds are polymerised by irradiation with UV light, preferably while applying a voltage to electrodes of the display.

15. Use of an LC medium according to one or more of claims 1 to 9 or an LC display according to one or more of claims 11 to 13 or a method according to claim 14 for energy-saving LC displays or for a process for the production of energy-saving LC displays.

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