Liquid crystal medium

Abstract

The present invention relates to a liquid crystal (LC) medium or LC material based on a mixture of polar compounds, the use thereof for optical, electro-optical and electronic purposes, in particular in LC displays, in particular in vertical alignment mode and / or fringing field switching mode, LC displays comprising vertical alignment mode and / or fringing field switching mode of said LC medium, in particular in LC displays in vertical alignment mode and / or fringing field switching mode of said LC medium, in particular in LC displays in vertical alignment mode and / or fringing field switching mode of said LC medium, in particular in LC displays in vertical alignment mode and / or fringing field switching mode of said LC medium. Especially an energy-saving LC display, and a method of manufacturing the LC display.

Description

Technical Field

[0001] The present invention relates to a liquid crystal (LC) medium or LC material based on a mixture of polar compounds, which is used for optical, electro-optical and electronic purposes, in particular for use in LC displays, especially in LC displays in vertical alignment mode and / or fringe field switching mode, an LC display in vertical alignment mode and / or fringe field switching mode comprising said LC medium, especially an energy-saving LC display, a method for preparing said LC medium, and a method for manufacturing said LC display. Background Art

[0002] So-called VA ("Vertical Alignment") displays are known, which have a wide viewing angle and a fast response time. The LC cell of a VA display contains an LC medium layer between two transparent electrodes, wherein the LC medium generally has a negative dielectric anisotropy value (Δε). In the off state, the molecules of the LC layer are vertically aligned with the electrode surface (homeotropic) or have an inclined homeotropic alignment. When a voltage is applied to the two electrodes, reorientation of the LC molecules parallel to the electrode surface occurs.

[0003] In addition, VA displays using an alignment layer prepared by photo-alignment, also called UV 2 A mode (see, for example, Q. Tang et al., SID Symposium Digest of Technical Papers 2018, 414 - 417) have been disclosed. These displays utilize an alignment layer prepared by obliquely irradiating a crosslinkable and photo-orientable monomer or prepolymer, such as a cinnamate chromophore, with linearly polarized UV light. As a result, a crosslinked alignment layer is formed, which induces a uniaxial alignment with a pretilt angle in the LC molecules near its surface. By changing the irradiation direction, a multi-domain structure with different pretilt directions can be obtained.

[0004] Through a specific polymer stabilization process step, the PS-VA ("Polymer Stabilized-Vertical Alignment") technology ensures that the liquid crystal in its black state is not completely vertical, but has a slight inclination. This is called "tilt" and ensures that the direction of LC molecule switching is locally defined.

[0005] In addition, so-called FFS ("fringe field switching") displays have been reported (see in particular S.H. Jung et al., Jpn. J. Appl. Phys., Vol. 43, No. 3, 2004, 1028), which contain two electrodes on the same substrate, one of the two electrodes being structured in a comb-like manner and the other being unstructured. This results in a strong so-called "fringe field", i.e., a strong electric field near the electrode edges, and an electric field having both a strong vertical component and a strong horizontal component throughout the cell. FFS displays have a low viewing angle dependence of the contrast. FFS displays typically contain an LC medium having a positive dielectric anisotropy and an alignment layer, typically of polyimide, which provides planar alignment for the molecules of the LC medium.

[0006] FFS displays can operate as active matrix or passive matrix displays. In the case of an active matrix display, individual pixels are typically addressed by integrated non-linear active elements, such as transistors (e.g., thin film transistors ("TFTs")), while in the case of a passive matrix display, individual pixels are typically addressed by multiplexing methods, as known in the prior art.

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

[0008] The UB-FFS ("ultrabright fringe field switching") technology or UBplus technology is based on FFS technology, which uses a negative dielectric single crystal to increase the total transmittance of the panel. UB-FFS is mainly used for smaller devices, and UBplus is mainly used for large screen displays. Specifically, a specific arrangement of liquid crystals allows the backlight illuminating the UB-FFS display to have a brighter transmittance, and the optimized use of light reduces the energy requirement of the UB-FFS display by at least one-third while improving the image quality. This results in a longer runtime and / or a brighter display.

[0009] Also known are so-called IPS (“in-plane switching”) displays, which include an LC layer with planar alignment between two substrates, where two electrodes are arranged only on one of the two substrates and preferably have a crossed comb structure. When a voltage is applied to the electrodes, an electric field with a significant component parallel to the LC layer is generated between them. This results in the reorientation of the LC molecules in the layer plane.

[0010] However, there are also several disadvantages to using an LC medium with negative dielectric anisotropy in VA or FFS displays. For example, they have significantly lower reliability compared to LC media with positive dielectric anisotropy.

[0011] The term “reliability” as used hereinafter refers to the performance quality of a display over a period of time and under different stress loads (such as light load, temperature, humidity, or voltage) that cause display defects such as image sticking (area and line image sticking), display unevenness (mura), dirt (yogore), etc., and which is known to those skilled in the art of LC displays. As a standard parameter for classifying reliability, the voltage holding ratio (VHR) value is usually used, which is a measure of the ability to maintain a constant voltage in a test display. The higher the VHR value, the better the reliability of the LC medium.

[0012] The reduced reliability of an LC medium with negative dielectric anisotropy in VA or FFS displays can be explained by the interaction of the LC molecules with the polyimide of the alignment layer, as a result of which ions are extracted from the polyimide alignment layer, and the LC molecules with negative dielectric anisotropy extract this ion more effectively.

[0013] This has led to new requirements for LC media used in VA or FFS displays. In particular, the LC medium must exhibit high reliability and a high VHR value after UV exposure. Further requirements are high resistivity, a large operating temperature range, short response times even at low temperatures, low threshold voltage, multiple gray levels, high contrast, wide viewing angles, and reduced image sticking.

[0014] Thus, in displays known in the prior art, the undesirable effects of so-called “image sticking” or “image burning” are often observed, where the image generated in an LC display by the temporary addressing of a single pixel remains visible even after the electric field in these pixels has been cut off, or after other pixels have been addressed.

[0015] On the one hand, this "image sticking" occurs if an LC medium with a low VHR is used. The UV component of sunlight or backlight can cause an unwanted decomposition reaction of the LC molecules therein and thus trigger the generation of ionic or radical impurities. These can accumulate particularly at the electrodes or the alignment layer, where they can reduce the effectively applied voltage.

[0016] Another problem observed in the prior art is that LC media for displays (including but not limited to VA and FFS displays) often do exhibit high viscosities and thus high switching times. To reduce the viscosity and switching time of the LC medium, it has been proposed in the prior art to add LC compounds with alkenyl groups. However, it has been observed that LC media containing alkenyl compounds often exhibit a reduction in reliability and stability, as well as a reduction in VHR, especially after exposure to UV radiation and visible light from the backlight of displays that normally do not emit UV light.

[0017] Accordingly, an object of the present invention is to provide an improved LC medium for VA-, PS-VA-, FFS-, polymer-stabilized PS-FFS-, UB-FFS-, UBplus and / or IPS displays, which does not exhibit the above-mentioned disadvantages or exhibits these disadvantages only to a small extent and has improved performance. Another object of the present invention is to provide VA-, PS-VA-, FFS-, UB-FFS-, UBplus and / or IPS displays having good transmittance, high reliability, especially VHR values after backlight exposure, high resistivity, a large operating temperature range, short response times even at low temperatures, low threshold voltages, multiple gray levels, high contrast and wide viewing angles, as well as reduced image sticking.

[0018] For VA-, PS-VA-, FFS-, UB-FFS-, UBplus and / or IPS displays, fast-switching mixtures that exhibit excellent reliability are required. To achieve fast-switching performance, low cell gaps are considered, for example cell gaps between 2.2 - 3.3 μm. At the same time, highly polar single crystals with dielectric anisotropy values Δε in the range of -15 to -10 are used to achieve fast-switching performance. However, the inherent solubility limitations of these highly polar single crystals can affect the achievable switching times. This can be solved by combining the highly polar single crystals with highly birefringent single crystals, which are characterized by birefringence values Δn in the range of 0.22 - 0.30, independent of polarity. Accordingly, another object of the present invention is to provide an improved LC mixture containing highly polar single crystals and highly birefringent single crystals, wherein the highly birefringent single crystals exhibit a favorable low ratio of rotational viscosity to clearing point γ1 / cl.p. and exhibit excellent solubility in the LC mixture, enabling the mixture to maintain excellent low-temperature stability.

[0019] It has been found that one or more of these objects can be achieved by providing an LC medium as disclosed and claimed hereinafter. SUMMARY OF THE INVENTION

[0020] Accordingly, the present invention relates to a liquid crystal medium comprising one or more compounds selected from compounds of formula III and / or formula IIIA and / or formula BC and / or formula PH-1

[0021]

[0022] and

[0023] one or more compounds of formula I

[0024]

[0025] wherein

[0026] R 11 、R 31 、R 32 、R 81 and R 82 each independently of one another represent H, an alkyl or alkoxy group having 1-15 C atoms, preferably having 1-7 C atoms, where one or more of these -CH2- groups may each independently of one another be replaced in such a way that O atoms are not directly connected to one another by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, replaced by -O-, -CO-O- or -O-CO-, and where one or more H atoms may be replaced by halogen,

[0027] X represents F, Cl, OCF3 or OCHF2, preferably represents F or OCF3, very preferably F, A 3 each occurrence independently of one another represents

[0028] a) 1,4-cyclohexylene or 1,4-cyclohexenylene, where one or two non-adjacent CH2 groups may be replaced by -O- or -S-,

[0029] b) 1,4-phenylene, where one or two CH groups may be replaced by N, or

[0030] c) a group selected from spiro[3.3]heptane-2,6-diyl, piperidine-1,4-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,

[0031] where the groups a), b) and c) are optionally mono- or polysubstituted by halogen atoms,

[0032] n represents 0, 1 or 2,

[0033] Z 3 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

[0034] L 11 、L 12 、L 31 and L 32 each independently of one another represents F, Cl, CF3 or CHF2, and

[0035] Y 1 、Y 2 、Y 3 、Y 4 each independently of one another represents H, F, Cl, CF3, CHF2, CH3 or OCH3, preferably H, CH3 or OCH3, very preferably H,

[0036] wherein H may be replaced by deuterium.

[0037] The present invention also relates to an LC display comprising a liquid crystal medium as described in the context, in particular a VA, PS-VA, FFS, PS-FFS, UB-FFS, UBplus, IPS, PS-IPS or UV 2 A display.

[0038] The present invention also relates to the use of a liquid crystal medium as described in the context in a VA, PS-VA, FFS, PS-FFS, UB-FFS, UBplus, IPS, PS-IPS or UV 2 A display.

[0039] The inventive concept is also applicable to high Δ-n applications, such as augmented reality and virtual reality (AR / VR) displays and / or lenses. For lenses, the Δ-n value is even higher than 0.1, up to 0.22.

[0040] The present invention also relates to a method for preparing an LC medium as described in the context, which comprises the step of mixing one or more compounds of formula I with one or more compounds of formula III and / or one or more compounds of formula IIIA and / or one or more compounds of formula BC and / or one or more compounds of formula PH-1, and optionally mixing with other LC compounds and / or additives.

[0041] The present invention also relates to a method of manufacturing an LC display as described in the context, which includes the step of filling or otherwise providing an LC medium as described in the context between the substrates of the display.

[0042] The LC medium according to the present invention allows for the achievement of one or more of the following advantageous effects, especially when used in an LC display having a small cell gap, for example, a cell gap between 2.2 and 3.3 μm:

[0043] - A reduced viscosity enabling a fast response time,

[0044] - A high birefringence,

[0045] - A favorable ratio of low rotational viscosity to clearing point γ1 / cl.p.,

[0046] - Excellent low-temperature stability,

[0047] - Reduced ODF display non-uniformity,

[0048] - High reliability and high VHR value after UV exposure and / or heat treatment,

[0049] - A low threshold voltage contributing to a reduction in driving voltage and enabling energy-saving display,

[0050] - Achieved a time- and cost-effective and energy-saving LC panel production process.

[0051] Surprisingly, it has been found that the LC medium according to the present invention exhibits a favorable combination of a reduced low rotational viscosity and a high birefringence. The relatively low rotational viscosity and high birefringence enable a fast LC medium mixture suitable for very small cell gaps. Furthermore, in terms of reliability, the LC medium according to the present invention exhibits a high VHR value and little or no undesired display non-uniformity effects, such as edge display non-uniformity.

[0052] As described below, alkenyl groups in the compounds of the LC medium are not considered 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 medium disclosed and claimed in the present application does not contain additives that initiate or enhance the participation of alkenyl groups in the polymerization reaction.

[0053] Unless otherwise specified, except for chiral dopants, the compounds disclosed in the context are preferably selected from non-chiral compounds.

[0054] 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.

[0055] As used herein, the term "substantially transmits" means that the filter transmits a substantial portion of the incident light of the desired wavelength(s), preferably at least 50% intensity. As used herein, the term "substantially blocks" means that the filter does not transmit a substantial portion of the incident light of the undesired wavelength, preferably at least 50% intensity. As used herein, the term "desired (undesired) wavelength" means, for example, for a bandpass filter, a wavelength within (outside) a given range λ, and for a cut-off filter, a wavelength above (below) a given λ value.

[0056] As used herein, the terms "active layer" and "switchable layer" mean layers in an electro-optical display, such as an LC display, that contain one or more molecules having structural and optical anisotropy, such as LC molecules, which change their orientation when subjected to an external stimulus such as an electric or magnetic field, resulting in a change in the transmittance of the layer for polarized or non-polarized light.

[0057] As used herein, the terms "tilt" and "tilt angle" should be understood to mean the tilt alignment of the LC molecules of the LC medium with respect to the cell surface in an LC display (preferably a PSA display in this document), and should be understood to include "pre-tilt" and "pre-tilt angle". The tilt angle in this document represents the average angle (<90°) between the longitudinal molecular axis of the LC molecules (LC director) and the surface of the planar outer plate forming the LC cell. A low absolute value of the tilt angle (i.e., a large deviation from the 90° angle) in this document corresponds to a large tilt. A suitable method for measuring the tilt angle is given in the examples. Unless otherwise specified, the tilt angle values disclosed in the context are related to this measurement method.

[0058] As used herein, the terms "reactive mesogen" and "RM" should be understood to mean compounds 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".

[0059] Unless otherwise specified, the term "polymerizable compound" as used herein should be understood to mean a polymerizable monomer compound.

[0060] The SA-VA display according to the present invention will be in a polymer-stabilized mode since it comprises an LC medium containing an RM (such as those described below) or is manufactured by using an LC medium containing an RM (such as those described below). Thus, as used herein, even if not explicitly mentioned, the term "SA-VA display" when referring to a display according to the present invention should be understood to mean a polymer-stabilized SA-VA display.

[0061] As used herein, the term "low molecular weight compound" should be understood to denote a monomer and / or a compound not prepared by a polymerization reaction, as opposed to a "polymeric compound" or "polymer".

[0062] As used herein, the term "non-polymerizable compound" will be understood to denote a compound that does not contain functional groups suitable for polymerization under the conditions normally applied to the polymerization of an RM.

[0063] As used herein, the term "mesogenic group" is known to those skilled in the art and is described in the literature, and it denotes 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. An overview of the terms and definitions used in connection with mesogenic or LC compounds is given in Pure Appl.Chem.2001,73(5),888 and C.Tschierske,G.Pelzl,S.Diele,Angew.Chem.2004,116,6340-6368.

[0064] As used herein, the term "spacer group" (also referred to hereinafter as "Sp") is known to those skilled in the art in the prior art and is described in the literature, see, for example, Pure Appl.Chem.2001,73(5),888 and C.Tschierske,G.Pelzl,S.Diele,Angew.Chem.2004,116,6340-6368. As used herein, the term "spacer group" or "spacer" denotes a flexible group, for example an alkylene group, which is connected to a mesogenic group and a polymerizable group(s) in a polymerizable mesogenic compound.

[0065] In the context, represents a trans-1,4-cyclohexylene ring, and represents a 1,4-phenylene ring.

[0066] In the group In it, the single bond between two ring atoms can be connected to any free position of the benzene ring.

[0067] If the terminal groups such as R shown in the formula according to the context 11 、R 21,22 、R 31,32,33 、R 41,42 、R 51,52 、R 61 、R 71 、R N1 ,N2 、R 81,82 、R 91,92,93 、R L1,L2 、R Q 、R R1,R2 or L represent an alkyl and / or an alkoxy group, then it can be straight-chain or branched-chain. It is preferably straight-chain, having 2, 3, 4, 5, 6 or 7 C atoms and correspondingly preferably represents ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy, as well as methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy or tetradecyloxy.

[0068] If one of the above terminal groups represents an alkyl group in which one or more CH2 groups are replaced by S, then it can be straight-chain or branched-chain. It is preferably straight-chain, having 1, 2, 3, 4, 5, 6 or 7 C atoms and correspondingly preferably represents thiomethyl, thioethyl, thiopropyl, thiobutyl, thiopentyl, thiohexyl or thioheptyl.

[0069] 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.

[0070] If one of the above terminal groups represents an alkoxy group or an oxaalkyl group, it can also contain one or more additional oxygen atoms, provided that the oxygen atoms are not directly connected to each other.

[0071] If one of the above terminal groups represents an alkyl group in which one of the CH2 groups has been replaced by -CH=CH-, it can be straight-chain or branched. It is preferably straight-chain and has 2 to 10 C atoms. Correspondingly, it represents, in particular, vinyl, prop-1- or -2-enyl, but-1-,-2- or -3-enyl, pent-1-,-2-,-3- or -4-enyl, hex-1-,-2-,-3-,-4- or -5-enyl, hept-1-,-2-,-3-,-4-,-5- or -6-enyl, oct-1-,-2-,-3-,-4-,-5-,-6- or -7-enyl, non-1-,-2-,-3-,-4-,-5-,-6-,-7- or -8-enyl, dec-1-,-2-,-3-,-4-,-5-,-6-,-7-,-8- or -9-enyl.

[0072] If one of the above terminal groups represents an alkyl or alkenyl group that is at least monosubstituted by a halogen, the group is preferably straight-chain and the halogen is preferably F or Cl. In the case of polysubstitution, the halogen is preferably F. The resulting groups also include 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.

[0073] In another preferred embodiment, one or more of the above terminal groups, such as R 11 、R 21,22 、R 31 ,32,33 、R 41,42 、R 51,52 、R 61 、R 71 、R N1,N2 、R 81,82 、R 91,92,93 、R L1,L2 、R Q 、R R1,R2 or L is selected from the following groups

[0074]

[0075] -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 very preferably selected from the following groups

[0076]

[0077] -OCH2OCH3,

[0078] -O(CH2)2OCH3, -O(CH2)3OCH3, -O(CH2)4OCH3, -O(CH2)2F, -O(CH2)3F, -O(CH2)4F.

[0079] The halogen is preferably F or Cl, very preferably F.

[0080] The group -CR 0 =CR 00 - is preferably -CH=CH-.

[0081] -CO-, -C(=O)- and -C(O)- represent a carbonyl group, that is

[0082] Preferred substituents L are, 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-chain alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group each having 1 - 25 C atoms, wherein one or more H atoms may optionally be replaced by F or Cl, an optionally substituted silyl group having 1 - 20 Si atoms, or an optionally substituted aryl group having 6 - 25, preferably 6 - 15 C atoms,

[0083] wherein R x represents H, F, Cl, CN, or a straight-chain, branched-chain or cyclic alkyl group having 1 - 25 C atoms, wherein one or more non-adjacent CH2 groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O- and / or S-atoms are not directly connected to each other, and wherein one or more H atoms are each optionally replaced by F, Cl, P- or P-Sp-, and Y 1 represents a halogen.

[0084] 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.

[0085] Preferably

[0086] wherein L has one of the meanings as described above.

[0087] In a preferred embodiment, the LC medium according to the invention comprises one or more compounds of formula I, wherein R 11 represents a straight-chain alkyl having 1 - 7 C atoms or an alkenyl having 2 - 7 carbon atoms.

[0088] In a preferred embodiment, the LC medium according to the invention comprises one or more compounds of formula I, preferably selected from the compounds of formulae Ia to Ic:

[0089]

[0090]

[0091] wherein X represents F, Cl, CF3, OCF3 or OCHF2, preferably represents F or OCF3, very preferably F, alkyl represents an alkyl having 1 - 7 C atoms, alkenyl represents an alkenyl having 2 - 7 carbon atoms, cycloalkyl represents a cycloalkyl having 3 - 12 C atoms, preferably cyclopropyl, cyclobutyl, cyclopentyl, cyclopropylalkyl, cyclobutylalkyl or cyclopentylalkyl.

[0092] Very preferred compounds of formulae Ia to Ic are selected from the compounds of formulae Ia - 1 to Ia - 2, Ib - 1 to Ib - 8 and Ic - 1 to Ic - 14.

[0093]

[0094]

[0095]

[0096]

[0097] wherein alkyl represents ethyl, n - propyl, n - butyl or n - pentyl, preferably n - propyl.

[0098] A preferred compound of formula I is Ia - 1, and the most preferred is the compound PGIGI - m - F, wherein m is preferably 1, 2, 3, 4, 5 or 6.

[0099] Preferred compounds of formula III are the compounds of formulae III - 1 to III - 6:

[0100]

[0101]

[0102] wherein the groups occurring have the same meanings as given under formula III above, and preferably

[0103] R 31 and R 32 each independently represents an alkyl, alkenyl or alkoxy group having at most 15 C atoms, preferably 1 - 7 C atoms, more preferably one or both of them represent alkoxy groups; or a cycloalkyl group having 3 - 6 C atoms,

[0104] R 33 represents an alkyl or alkenyl group having at most 7 C atoms or the group Cy - C n H 2n+1 -,

[0105] 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,

[0106] 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, preferably represents cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl,

[0107] (O) represents O or a single bond,

[0108] L 31 and L 32 each independently represents F or Cl, preferably both represent F, and

[0109] Y 3 represents H, F, Cl, CF3, CHF2, CH3 or OCH3, preferably H or CH3.

[0110] In another preferred embodiment, the LC medium comprises one or more compounds of formula III - 1 selected from formulas III - 1 - 1 to III - 1 - 20, preferably the compounds of formulas III - 1 - 1 and III - 1 - 11,

[0111]

[0112]

[0113]

[0114] wherein alkyl and alkyl * each independently represents a straight - chain alkyl group having 1 - 6 C atoms, alkenyl and alkenyl * each independently represents a straight - chain alkenyl group having 2 - 6 carbon atoms, alkoxy and alkoxy * each independently represents a straight - chain alkoxy group having 1 - 6 C atoms, L 31 and L 32Each independently represents F or Cl, preferably both are F.

[0115] Highly preferred compounds of formula III-1-1 are selected from the following sub-formulas,

[0116]

[0117]

[0118] Highly preferred compounds of formula III-1-11 are selected from the following sub-formulas,

[0119]

[0120]

[0121] Highly preferred compounds of formula III-2 are as follows,

[0122]

[0123]

[0124] where alkoxy represents a straight-chain alkoxy group having 1-6 C atoms, preferably ethoxy, propoxy, butoxy or pentyloxy, very preferably ethoxy or propoxy, and alkenyl represents a straight-chain alkenyl group having 2-6 C atoms.

[0125] Highly preferred compounds of formula III-6 are selected from the following formulas,

[0126]

[0127]

[0128]

[0129] where R 32 represents an alkyl group having 1-7 C atoms, preferably ethyl, n-propyl or n-butyl, or alternatively represents cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl, or alternatively represents -(CH2) n F, where n is 2, 3, 4 or 5, preferably C2H4F.

[0130] Preferred compounds of formula III are III-1-1-3, III-1-1-4, III-1-1-5, III-2-7 and III-6-2, and the most preferred are compounds B(S)-2O-O4, B(S)-2O-O5, B(S)-2O-O6, B(S)-1V1O-O1(c5) and COB(S)-2-O4.

[0131] Preferably, the LC medium further comprises one or more compounds of formula IIIA:

[0132]

[0133] wherein R 31 、R 32 、A 3 、Z 3 、L 31 、L 32 、Y 1 、Y 2 、Y 3 、Y 4 and n have the meanings given above for formula III.

[0134] In a preferred embodiment of the present invention, the LC medium comprises one or more compounds of formula IIIA-1:

[0135]

[0136] wherein the groups occurring therein have the same meanings as those given under formula IIIA above, and preferably

[0137] R 31 and R 32 each independently of one another represent an alkyl, alkenyl or alkoxy group having at most 15 C atoms, preferably 1-7 C atoms, more preferably one or both of them represent an alkoxy group; or a cycloalkyl group having 3-6 C atoms,

[0138] L 31 and L 32 each independently of one another represent F or Cl, preferably both are F.

[0139] In another preferred embodiment, the LC medium comprises one or more compounds of formula IIIA-1 selected from formula IIIA-1-1 to IIIA-1-20, preferably formula IIIA-1-8 and IIIA-1-18,

[0140]

[0141]

[0142]

[0143] wherein alkyl and alkyl * each independently of one another represent a straight-chain alkyl group having 1-6 C atoms or a cycloalkyl group having 3-6 C atoms, alkenyl and alkenyl * each independently of one another represent a straight-chain alkenyl group having 2-6 carbon atoms, alkoxy and alkoxy* each independently represents a straight-chain alkoxy group having 1 to 6 carbon atoms, L 31 and L 32 each independently represents F or Cl, preferably both are F.

[0144] Preferably, the LC medium contains one or more compounds of formula IIIA-1-8 selected from the following sub-formulas:

[0145]

[0146] Preferably, the LC medium contains one or more compounds of formula IIIA-1-18 selected from the following sub-formulas:

[0147]

[0148] In another preferred embodiment of the present invention, the LC medium contains one or more compounds of formula IIIA-2

[0149]

[0150] wherein L 31 and L 32 have the same meaning as given under formula IIIA, (O) represents oxygen or a single bond,

[0151] R 33 represents an alkyl or alkenyl group having at most 7 carbon atoms or the group Cy-C n H 2n+1 -,

[0152] 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

[0153] 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 carbon atoms, or by a halogen or CN, preferably represents cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl.

[0154] The compound of formula IIIA-2 replaces the compound of formula III or is additionally contained in the LC medium, preferably additionally contained.

[0155] Highly preferred compounds of formula IIIA-2 are as follows,

[0156]

[0157]

[0158] where alkoxy represents a straight-chain alkoxy group having 1 to 6 carbon atoms.

[0159] In another preferred embodiment, the LC medium comprises one or more type IIIA compounds selected from the compounds of formulae IIIA-3 to IIIA-5,

[0160]

[0161] wherein the groups occurring have the same meanings as given in formula III, and R 31 preferably represents a straight-chain alkyl or cycloalkyl group, and R 32 preferably represents an alkoxy group each having 1-7 C atoms.

[0162] In a preferred embodiment of the present invention, the LC medium comprises one or more type IIIA-6 compounds:

[0163]

[0164] wherein the groups occurring have the same meanings as given in formula III, and preferably R 31 and R 32 each independently of one another represent an alkyl, alkenyl or alkoxy group having at most 15 C atoms, preferably having 1-7 C atoms, more preferably one or both of them represent an alkoxy group.

[0165] Highly preferred type IIIA-6 compounds are selected from the following formulae:

[0166]

[0167]

[0168] where R 32 represents an alkyl group having 1-7 C atoms, preferably ethyl, n-propyl or n-butyl, or alternatively represents cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl, or alternatively represents -(CH2) n F, where n is 2, 3, 4 or 5, preferably C2H4F.

[0169] In a preferred embodiment of the present invention, the LC medium comprises at least one type I compound, at least one type III compound and at least one type IIIA compound.

[0170] The LC medium of the present invention comprises one or more compounds selected from formula BC difluorodibenzochroman, formula CR chroman, and formula PH-1 and PH-2 fluorinated phenanthrenes,

[0171]

[0172] wherein

[0173] R 81 and R 82Each independently represents H, an alkyl or alkoxy group having 1 to 15 C atoms, preferably 1 to 7 C atoms, where one or more -CH2- groups in these groups can each independently be -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- substituted in such a way that O atoms are not directly connected to each other, and one or more H atoms can be replaced by halogen, R 81 and R 82 preferably each independently represents an alkyl or alkoxy group having 1 to 6 C atoms, or a cycloalkyl group having 3 to 6 C atoms,

[0174] c is 0, 1 or 2, and

[0175] Y 1 、Y 2 、Y 3 、Y 4 each independently represents H, F, Cl, CF3, CHF2, CH3 or OCH3.

[0176] The LC medium according to the invention preferably contains compounds of formula BC, CR, PH-1, PH-2 in an amount of 3 to 20% by weight, in particular 3 to 15% by weight.

[0177] Particularly preferred compounds of formula BC and CR are compounds BC-1 to BC-7 and CR-1 to CR-5,

[0178]

[0179]

[0180] where

[0181] alkyl and alkyl * each independently represents a straight-chain alkyl group having 1 to 6 C atoms or a cycloalkyl group having 3 to 6 C atoms, and

[0182] alkenyl and alkenyl * each independently represents a straight-chain alkenyl group having 2 to 6 C atoms.

[0183] A particularly preferred compound of formula BC is compound B(A)-2O-O2,

[0184]

[0185] Particularly preferred compounds of formula PH-1 are compounds B(P)-2O-O3 and B(P)-2O-O4,

[0186]

[0187] The following lists other preferred embodiments of the LC medium according to the present invention, including any combination thereof:

[0188] Preferably, the LC medium further comprises one or more compounds of formula II,

[0189]

[0190] wherein each group is independent of one another and, each time it occurs, has the following meanings, the same or different:

[0191] R 21 and R 22 are a straight-chain, branched-chain or cyclic alkyl or alkoxy group having 1 to 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-, 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 to 6 C atoms,

[0192] R 0 ,R 00 is H or an alkyl group having 1 to 12 C atoms,

[0193] A 1 and A 2 are groups selected from the following formulae

[0194]

[0195] preferably formulae A1, A2, A3, A4, A5, A6, A9 and A10, very preferably formulae A1, A2, A3, A4, A5, A9 and A10,

[0196] 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,

[0197] L 1 ,L 2 ,L 3 and L 4is F, Cl, OCF3, CF3, CH3, CH2F or CHF2, preferably F or Cl, very preferably F,

[0198] Y is H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, very preferably H,

[0199] L C is CH3 or OCH3, preferably CH3,

[0200] a1 is 0, 1 or 2,

[0201] a2 is 0 or 1.

[0202] Preferably, the LC medium comprises one or more compounds of formula II selected from compounds of formulae IIA, IIB, IIC, IID, IIE and IIF

[0203]

[0204] where each group is the same or different at each occurrence and each independently of one another has the following meanings:

[0205] R 21 、R 22 are H, alkyl, alkoxy or alkenyl having up to 15 C atoms, which are unsubstituted or mono-substituted by F, Cl, CN or CF3, and wherein additionally 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 connected to one another,

[0206] substituted,

[0207] L 1 to L 4 are F, Cl, CF3 or CHF2,

[0208] Y is H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, particularly preferably H,

[0209] Z 1 、Z 2 are a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CH=CHCH2O,

[0210] p is 0, 1 or 2, and

[0211] q is 0 or 1.

[0212] Preferred compounds of formulae IIA, IIB, IIC, IID and IIE are those in which R 22 represents alkyl or alkoxy having up to 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.

[0213] Further preferred compounds of formulae IIA, IIB, IIC, IID and IIE are those in which R 21 or R 22 represents or contains a cycloalkyl or cycloalkoxy group, preferably selected from

[0214]

[0215] 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

[0216]

[0217]

[0218] Further preferred compounds of formulae IIA, IIB, IIC, IID and IIE are as follows.

[0219]

[0220]

[0221]

[0222]

[0223]

[0224]

[0225]

[0226]

[0227]

[0228]

[0229]

[0230] wherein the parameter a represents 1 or 2, alkyl and alkyl * each independently of one another represents a straight-chain or branched alkyl having 1 - 6 C atoms, alkenyl represents a straight-chain or branched alkenyl having 2 - 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-.

[0231] 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, IIA-18, IIA-40, IIA-41, IIA-42, IIA-43, IIA-67, IIA-69 and IIA-81.

[0232] Preferably, the LC medium comprises one or more compounds of formula IIA-2 selected from the following sub-formulae:

[0233]

[0234]

[0235] 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:

[0236]

[0237]

[0238] Further preferably, the LC medium comprises one or more compounds of formula IIA-10 selected from the following sub-formulae:

[0239]

[0240] Alternatively, preferably in addition to the compounds of formulae IIA-10-1 to IIA-10-6, the LC medium further comprises one or more compounds of the following formulae:

[0241]

[0242]

[0243] Further preferably, the LC medium comprises one or more compounds of formula IIA-16 selected from the following sub-formulae:

[0244]

[0245] Further preferably, the LC medium comprises one or more compounds of formula IIA-40 selected from the following sub-formulas:

[0246]

[0247] Alternatively, preferably in addition to the compounds of formulas IIA-40-1 to IIA-40-5, the LC medium further comprises one or more compounds of the following formula:

[0248]

[0249]

[0250] Further preferably, the LC medium comprises one or more compounds of formula IIA-42 selected from the following sub-formulas:

[0251]

[0252]

[0253] Further preferably, the LC medium comprises one or more compounds of formula IIA-67 selected from the following sub-formulas:

[0254]

[0255] Further preferably, the LC medium comprises one or more compounds of formula IIA-69 selected from the following sub-formulas:

[0256]

[0257] Further preferably, the LC medium comprises one or more compounds of formula IIA-81 selected from the following sub-formulas:

[0258]

[0259]

[0260] The preferred LC medium additionally comprises one or more compounds of formula IIA-Y

[0261]

[0262] wherein R 21 and R 22 have one of the meanings given in formula IIA above, and L 1 and L 2 independently represent F or Cl.

[0263] Preferred compounds of formula IIA-Y are selected from the following sub-formulas

[0264]

[0265]

[0266]

[0267] wherein, Alkyl and Alkyl * each independently represent a straight-chain or branched alkyl group having 1-6 C atoms, Alkoxy represents a straight-chain or branched alkoxy group having 1-6 C atoms, Alkenyl and Alkenyl * each independently represent a straight-chain or branched alkenyl group 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-.

[0268] Particularly preferred compounds of formula IIA-Y are selected from the following sub-formulas:

[0269]

[0270] wherein Alkoxy and Alkoxy * have the meanings defined above and preferably represent methoxy, ethoxy, n-propoxy, n-butoxy or n-pentyloxy.

[0271] In another preferred embodiment, the LC medium comprises one or more compounds of formula IIB selected from formulas IIB-1 to IIB-32,

[0272]

[0273]

[0274]

[0275]

[0276]

[0277] wherein alkyl and alkyl *Each independently represents a straight-chain or branched alkyl group having 1 to 6 carbon atoms, alkenyl represents a straight-chain or branched alkenyl group having 2 to 6 carbon 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-.

[0278] Particularly preferred LC media according to the invention comprise one or more compounds selected from the group consisting of formulae IIB-2, IIB-11 and IIB-17.

[0279] Preferably, the LC medium comprises one or more compounds of formula IIB-11 selected from the following sub-formulae:

[0280]

[0281]

[0282] Alternatively, preferably in addition to the compounds of formulae IIB-11-1 to IIB-11-5, the LC medium further comprises one or more compounds of formulae IIB-11a-1 to IIB-11a-6:

[0283]

[0284]

[0285] Preferably, the LC medium comprises one or more compounds of formula IIB-17 selected from the following sub-formulae:

[0286]

[0287] In another preferred embodiment, the LC medium comprises one or more compounds of formula IIC selected from formula IIC-1

[0288]

[0289] wherein alkyl and alkyl * Each independently represents a straight-chain alkyl group having 1 to 6 carbon atoms, preferably contained in an amount of 0.5 to 5% by weight, in particular 1 to 3% by weight.

[0290] In another preferred embodiment, the LC medium comprises one or more compounds of formula IID selected from the following formulae:

[0291]

[0292]

[0293]

[0294] wherein alkyl and alkyl * each independently of one another represent a straight-chain or branched alkyl group having 1 to 6 C atoms, alkenyl represents a straight-chain or branched 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-.

[0295] Particularly preferred LC media according to the invention comprise one or more compounds of the formulae IID-1, IID-4, IID-12 and / or IID-19.

[0296] Very preferably, the compounds of the formula IID are selected from the following sub-formulae of IID-1,

[0297]

[0298]

[0299]

[0300]

[0301] wherein v is 1, 2, 3, 4, 5 or 6.

[0302] Very preferably, the compounds of the formula IID are selected from the following sub-formulae of IID-4,

[0303]

[0304]

[0305]

[0306]

[0307]

[0308] wherein v is 1, 2, 3, 4, 5 or 6.

[0309] Very preferably, the compounds of the formula IID are selected from the following sub-formulae of IID-12,

[0310]

[0311]

[0312]

[0313] wherein v is 1, 2, 3, 4, 5 or 6.

[0314] In a preferred embodiment, the LC medium comprises one or more compounds of formula IID-12a

[0315]

[0316] wherein R 21 , Y and q have the meanings given in formula IID, and R 23 is wherein r is 0, 1, 2, 3, 4, 5 or 6 and s is 1, 2 or 3.

[0317] Preferred compounds of formula IID-10a are compounds IID-12a-1 to IID-12a-14:

[0318]

[0319]

[0320]

[0321] Very preferred compounds of formula IID are selected from the following sub-formulae of IID-19,

[0322]

[0323]

[0324]

[0325]

[0326] wherein v is 1, 2, 3, 4, 5 or 6.

[0327] In a preferred embodiment, the LC medium comprises one or more compounds of formula IIE selected from the following formulae:

[0328]

[0329]

[0330]

[0331]

[0332]

[0333]

[0334]

[0335]

[0336]

[0337]

[0338]

[0339] wherein the parameter 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—.

[0340] Particularly preferred LC media according to the invention comprise one or more compounds selected from the group consisting of formulae IIE-2, IIE-8, IIE-10, IIE-16, IIE-18, IIE-37, IIE-38, IIE-39 and IIE-40.

[0341] Preferably, the LC medium comprises one or more compounds of formula IIE-2 selected from the following sub-formulae:

[0342]

[0343] Preferably, the LC medium comprises one or more compounds of formula IIE-10 selected from the following sub-formulae:

[0344]

[0345]

[0346] In another preferred embodiment, the LC medium comprises one or more compounds of formula IIF selected from the following formulae:

[0347]

[0348] wherein alkyl and alkyl *Each independently of one another represents a straight-chain or branched alkyl group having 1 to 6 carbon atoms.

[0349] Preferably, the LC medium comprises one or more compounds of formula IIF-2 selected from the following sub-formulas:

[0350]

[0351]

[0352] Particularly preferably, the LC medium according to the invention comprises one or more compounds selected from formula IIA-2, IIA-8, IIA-10, IIA-16, II-18, IIA-40, IIA-41, IIA-42, IIA-43, IIA-67, IIA-69, IIA-81, IIB-2, IIB-10, IIB-16, IIC-1 and IID-1, IID-4, IID-12, IID-19, IIE-2, IIE-8, IIE-10, IIE-16, IIE-18, IIE-37, IIE-38, IIE-39, IIE-40 and IIF-2 or their sub-formulas.

[0353] The proportion of the formula IIA and / or IIB compounds in the entire mixture is preferably at least 20% by weight.

[0354] In a preferred embodiment, the LC medium comprises one or more compounds of formula IV,

[0355]

[0356] wherein

[0357] R 41 represents an unsubstituted alkyl group having 1 to 7 carbon atoms, wherein additionally, one or more CH2 groups can be

[0358]

[0359] replaced, or an unsubstituted alkenyl group having 2 to 7 carbon atoms, preferably an n-alkyl group, particularly preferably having 2, 3, 4 or 5 carbon atoms, and

[0360] R 42 represents an unsubstituted alkyl group having 1 to 7 carbon atoms, or a cycloalkyl group having 3 to 6 carbon atoms or an unsubstituted alkoxy group having 1 to 6 carbon atoms (all preferably having 2 to 5 carbon atoms), an unsubstituted alkenyl group having 2 to 7 carbon atoms, preferably having 2, 3 or 4 carbon atoms, more preferably vinyl or 1-propenyl and especially vinyl.

[0361] The compounds of formula IV are preferably selected from the compounds of formula IV-1 to IV-4,

[0362]

[0363] wherein

[0364] alkyl and alkyl * each independently represents an alkyl group having 1 - 7 C atoms, preferably having 2 - 5 C atoms,

[0365] alkenyl represents an alkenyl group having 2 - 5 C atoms, preferably having 2 - 4 C atoms, particularly preferably 2 C atoms,

[0366] alkenyl * represents an alkenyl group having 2 - 5 C atoms, preferably having 2 - 4 C atoms, particularly preferably having 2 - 3 C atoms, and

[0367] alkoxy represents an alkoxy group having 1 - 5 C atoms, preferably having 2 - 4 C atoms.

[0368] Preferably, the LC medium comprises one or more compounds selected from the compounds of formulae IV - 1 - 1 to IV - 1 - 14

[0369]

[0370]

[0371]

[0372] wherein alkyl represents methyl, ethyl, n - propyl, isopropyl, n - butyl, isobutyl or n - pentyl.

[0373] Very preferably, the LC medium according to the invention comprises one or more compounds of formula IV - 2 - 1 and / or IV - 2 - 2

[0374]

[0375] Very preferably, the LC medium according to the invention comprises a compound of formula IV - 3, in particular a compound selected from formulae IV - 3 - 1 to IV - 3 - 9

[0376]

[0377]

[0378] The LC medium according to the invention preferably comprises one or more compounds CC-n-V and / or CC-n-Vm, in particular CC-3-V, CC-4-V, CC-3-V1 and / or CC-4-V1, preferably in a total concentration in the range of 15 - 70%, preferably 25 - 55%, very preferably 30 - 50%. CC-3-V is preferably used at a concentration of 5 - 60%, in particular 10 - 55%.

[0379] In another preferred embodiment, the LC medium according to the invention comprises one or more compounds of formula IV-3 selected from the compounds of formulae IV-3-10 to IV-3-25:

[0380]

[0381]

[0382]

[0383] 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:

[0384]

[0385] In another preferred embodiment, the LC medium comprises one or more compounds of formula IV-4 and its sub-formulae, wherein one or both of "alkenyl" and "alkenyl * " represent wherein

[0386] m is 0, 1 or 2, n is 0, 1 or 2, very preferably a compound selected from formulae IV-4-3 to IV-4-6.

[0387] Very preferably, the LC medium according to the invention comprises one or more compounds of formula IV-1 and its sub-formulae and / or one or more compounds of formula IV-3 and its sub-formulae and / or one or more compounds of formula IV-4 and its sub-formulae, wherein the total concentration of these compounds of formula IV-1 is in the range of 1 - 30%.

[0388] The LC medium according to the invention preferably additionally comprises one or more compounds of formula IVa,

[0389]

[0390] wherein

[0391] R 41 and R 42 each independently of one another represent a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkoxy having at most 12 C atoms, or a cycloalkyl having 3 - 6 C atoms,

[0392] represents

[0393] Z 4 represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -C4H8- or -CF=CF-.

[0394] Preferred compounds of formula IVa are shown below:

[0395]

[0396]

[0397] wherein alkyl and alkyl * each independently represent a straight-chain alkyl group having 1-6 C atoms.

[0398] The LC medium according to the invention preferably comprises at least one compound of formula IVa-1 and / or formula IVa-2.

[0399] The proportion of the compound of formula IVa in the whole mixture is preferably at least 5 wt%.

[0400] Preferably, the LC medium comprises one or more compounds of formula IVb-1 to IVb-3

[0401]

[0402] wherein

[0403] alkyl and alkyl * each independently represent a straight-chain alkyl group having 1-6 C atoms, or a cycloalkyl group having 3-6 C atoms, preferably alkyl represents methyl, and

[0404] alkenyl and alkenyl * each independently represent a straight-chain alkenyl group having 2-6 C atoms.

[0405] The proportion of the compounds of formula IV-1 to IV-3 in the whole mixture is preferably at least 3 wt%, especially ≥5 wt%.

[0406] Among the compounds of formula IVa-1 to IVa-4, the compound of formula IVa-2 is particularly preferred.

[0407] Among the compounds of formula IVb-1 to IVb-3, the compound of formula IVb-2 is particularly preferred.

[0408] Particularly preferred compounds of formulas IV-1 to IV-3 are selected from the following formulas

[0409]

[0410]

[0411] where alkyl * denotes an alkyl group having 1 to 6 C atoms and preferably denotes n-propyl.

[0412] The LC medium of the present invention particularly preferably contains one or more compounds of formulas IVb-1-1, IVb-2-3 and / or IVb-2-4.

[0413] In another preferred embodiment, the LC medium according to the invention contains one or more compounds of formula V

[0414]

[0415] wherein

[0416] R 51 and R 52 each independently represent H, an alkyl group having at most 15 C atoms, an alkoxy group or an alkenyl group, 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 groups can be replaced by -O-, -S-, -C≡C-, -CF2O-, -OCF2-, -OC-O-, -O-CO-

[0417] in such a way that O atoms are not directly connected to each other, and preferably represent an alkyl group having 1 to 7 C atoms, preferably an n-alkyl group, particularly preferably an n-alkyl group having 1 to 5 C atoms, an alkoxy group having 1 to 6 C atoms, preferably an n-alkoxy group, particularly preferably an n-alkoxy group having 2 to 5 C atoms, an alkoxyalkyl group, an alkenyl group or an alkenyloxy group having 2 to 7 C atoms, preferably having 2 to 4 C atoms, preferably an alkenyloxy group,

[0418] are the same or different and represent

[0419]

[0420] wherein

[0421] preferably represent

[0422] Z 51 , Z 52each independently 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

[0423] n is 1 or 2,

[0424] wherein one or more compounds of formula V are different from those of formula I.

[0425] Compounds of formula V are preferably selected from compounds of formulae V-1 to V-17:

[0426]

[0427]

[0428]

[0429] wherein R 51 and R 52 have the meanings described above.

[0430] R 51 and R 52 preferably each independently represents a straight-chain alkyl or alkenyl group.

[0431] Preferred LC media comprise one or more compounds of formulae V-1, V-3, V-4, V-6, V-7, V-10, V-11, V-12, V-14, V-15 and / or V-16.

[0432] The LC media according to the invention very particularly preferably comprise compounds of formula V-10 and / or IV-1, especially in an amount of 5 - 30%.

[0433] A preferred compound of formula V-10 is shown below:

[0434]

[0435] The LC media according to the invention particularly preferably comprise a combination of a tricyclic compound of formula V-10a and / or formula V-10b with one or more bicyclic compounds of formula IV-1. The total proportion of the compound of formula V-10a and / or V-10b in combination with one or more compounds selected from compounds of formula IV-1 dicyclohexyl compounds is 5 - 40%, very particularly preferably 15 - 35%.

[0436] Particularly preferred LC media comprise compounds V-10a and IV-1-1

[0437]

[0438]

[0439] Compound V-10a and IV-1-1 are preferably present in the mixture at a concentration of 5-30%, very preferably 10-25%, based on the entire mixture.

[0440] The preferred LC medium comprises at least one compound selected from the following compounds:

[0441]

[0442] wherein R 41 , R 42 , R 51 and R 52 have the meanings as described above. Preferably, in compounds V-6, I and IV, R 41 and R 51 represent an alkyl or alkenyl having 1-6 or 2-6 C atoms respectively, and R 42 and R 52 represent an alkenyl having 2-6 C atoms. Preferably, in compound V-14, R 51 represents an alkyl or alkenyl having 1-6 or 2-6 C atoms, and R 52 represents an alkyl having 1-6 C atoms.

[0443] In another preferred embodiment, the LC medium according to the invention comprises one or more compounds of formula V-7, preferably selected from compounds of formulae V-7a to V-7e:

[0444]

[0445]

[0446] wherein alkyl represents an alkyl having 1-7 C atoms, alkenyl represents an alkenyl having 2-7 C atoms, cycloalkyl represents a cycloalkyl having 3-12 C atoms, preferably cyclopropyl, cyclobutyl, cyclopentyl, cyclopropylalkyl, cyclobutylalkyl or cyclopentylalkyl.

[0447] Very preferably, the compounds of formulae V-7a to V-7e are selected from the compounds of the following sub-formulae:

[0448]

[0449]

[0450]

[0451]

[0452] wherein alkyl represents ethyl, n-propyl, n-butyl or n-pentyl, preferably n-propyl.

[0453] Further preferably, the compound of formula V, wherein R 51 and R 52 each independently represent a straight-chain alkyl having 1-7 C atoms or an alkenyl having 2-7 C atoms.

[0454] In a preferred embodiment of the present invention, the LC medium further comprises one or more compounds of formulae VI-1 to VI-22,

[0455]

[0456]

[0457]

[0458]

[0459] wherein

[0460] R 61 represents a straight-chain alkyl or alkoxy having 1-6 C atoms, or a cycloalkyl having 3-6 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.

[0461] R 61 preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy.

[0462] X preferably represents F or OCH3, very preferably F.

[0463] The LC medium according to the present invention preferably comprises the terphenyls of formulae VI-1 to VI-22 in an amount of 2-30 wt%, especially 5-20 wt%.

[0464] Particularly preferred are the compounds of formulae VI-2, VI-18 and VI-20, wherein X represents F. Among these compounds, R 61 preferably represents an alkyl and an alkoxy, each having 1-5 C atoms. In the compound of formula VI-18, R 61 preferably represents an alkyl or an alkenyl, especially an alkyl. In the compound of formula VI-19, R 61 preferably represents an alkyl. In the compounds of formulae VI-20 to VI-22, X preferably represents F.

[0465] If the Δn value of the mixture ≥ 0.1, the terphenyls of formulas VI-1 to VI-22 are preferably used in the LC medium according to the present invention. The preferred LC medium contains 2-20 wt% of one or more terphenyl compounds selected from the compounds of formulas VI-1 to VI-22.

[0466] In another preferred embodiment of the present invention, the LC medium additionally contains one or more compounds of formulas VII-1 to VII-9

[0467]

[0468] wherein

[0469] R 71 each independently of one another has one of the meanings of R in formula IIA 21 as shown, and

[0470] w and x each independently of one another represent 1-6.

[0471] Particularly preferred is an LC medium containing at least one compound of formula VII-9.

[0472] An LC medium which contains one or more substances containing a tetrahydronaphthyl or naphthyl unit, such as the compounds of formulas N-1 to N-5,

[0473]

[0474] wherein R N1 and R N2 each independently of one another have the meanings described for R 21 preferably represent a straight-chain alkyl, straight-chain alkoxy or straight-chain alkenyl, and

[0475] Z N1 and Z N2 each independently of one another represent -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.

[0476] An LC medium which contains one or more indane compounds of formula In

[0477]

[0478] wherein

[0479] R 91 ,R 92 ,

[0480] R 93 each independently of one another represents a straight-chain alkyl, alkoxy, alkoxyalkyl or alkenyl having 1 to 6 C atoms, or a cycloalkyl having 3 to 6 C atoms,

[0481] R 92 and R 93 may also represent a halogen, preferably F,

[0482] represents

[0483]

[0484] i represents 0, 1 or 2.

[0485] Preferred compounds of formula In are the compounds of formulae In-1 to In-16 described below:

[0486]

[0487]

[0488]

[0489] Particularly preferred are the compounds of formulae In-1, In-2, In-3 and In-4.

[0490] The compounds of formula In and sub-formulae In-1 to In-16 are preferably used in the LC medium according to the invention at a concentration of ≥ 5 wt%, in particular 5 - 30 wt% and very particularly preferably 5 - 25 wt%.

[0491] An LC medium which comprises one or more compounds of formulae L-1 to L-8,

[0492]

[0493]

[0494] wherein

[0495] R L1 and R L2 each independently of one another have the meanings described above for R in formula IIA, and alkyl represents an alkyl having 1 to 6 C atoms. The parameter s represents 1 or 2. 21 The compounds of formulae L-1 to L-8 are preferably used at a concentration of 5 - 15 wt%, in particular 5 - 12 wt% and very particularly preferably 8 - 10 wt%.

[0496]

[0497] ​An LC medium comprising one or more terphenyl compounds selected from the following formulas:

[0498]

[0499] wherein

[0500] R Q is an alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 - 9 C atoms or an alkenyl or alkenoxy having 2 - 9 C atoms, all optionally fluorinated,

[0501] X Q is F, Cl, a haloalkyl or alkoxy having 1 - 6 C atoms or a haloalkenyl or alkenoxy having 2 - 6 C atoms,

[0502] L Q1 -L Q6 are independently of one another H or F, where at least one of the L Q1 -L Q6 is F.

[0503] Preferred compounds of formula Q are those in which R Q represents a straight-chain alkyl having 2 - 6 C atoms, very preferably ethyl, n-propyl or n-butyl.

[0504] Preferred compounds of formula Q are those in which L Q3 and L Q4 are F. Further preferred compounds of formula Q are those in which one or two of the L Q3 、L Q4 and L Q1 and L Q2 are F.

[0505] Preferred compounds of formula Q are those in which X Q represents F or OCF3, very preferably F.

[0506] Compounds of formula Q are preferably selected from the following sub-formulas

[0507]

[0508] wherein R Q has one of the meanings of formula Q or one of its preferred meanings given in the context, and is preferably ethyl, n-propyl or n-butyl.

[0509] Particularly preferred are compounds of formula Q1, especially those in which R Q is n-propyl or cyclopentyl.

[0510] Preferably, the proportion of the formula Q compound in the LC medium is >0 to ≤5 wt%, very preferably 0.05 - 2 wt%, more preferably 0.1 - 1 wt%, and most preferably 0.1 - 0.8 wt%.

[0511] Preferably, the LC medium contains 1 - 5 kinds, preferably 1 or 2 kinds of the formula Q compound.

[0512] Adding the formula Q terphenyl compound to the LC mixture of the polymerizable LC medium can reduce ODF non-uniformity, while maintaining high UV absorption, achieving fast and complete polymerization, generating a strong and fast tilt angle, and improving the UV stability of the LC medium.

[0513] In addition, adding the formula Q compound with positive dielectric anisotropy to the LC medium with negative dielectric anisotropy can better control the dielectric constant ε || and ε ⊥ values, especially can achieve a high dielectric constant ε || value, and keep the dielectric anisotropy Δη constant, thereby reducing the kickback voltage and reducing image sticking.

[0514] The LC medium contains one or more diphenylacetylene compounds, such as PTP, CPTP, PTY, CPTY, PPTUI.

[0515] The LC medium additionally contains PUS.

[0516] The LC medium according to the present invention preferably contains

[0517] - one or more compounds of formula I or its sub-formulas, preferably the compound of formula Ia-1, preferably in a proportion of 2 - 30 wt%, very preferably 5 - 20 wt%, and most preferably 8 - 12 wt%, based on the whole mixture;

[0518] and / or

[0519] - one or more compounds of formula III, preferably the compounds of formula III-1 and / or III-6, very preferably the compounds of formula III-1-1 and / or III-6-2, wherein the total concentration of formula III-1 is preferably in the range of 2 - 20 wt%, very preferably 7 - 14 wt%, based on the whole mixture; wherein the total concentration of formula III-6 is preferably in the range of 2 - 20 wt%, very preferably 8 - 12 wt%, based on the whole mixture;

[0520] and / or

[0521] - one or more compounds of formula IIIA, preferably the compound of formula IIIA-1, very preferably the compound of formula IIIA-1-6, preferably with a total concentration in the range of 2 - 8 wt%, very preferably 3 - 5 wt%, based on the whole mixture;

[0522] and / or

[0523] -One or more compounds of formula BC or its sub-formulas, preferably with a total concentration in the range of 0.1-10% by weight, more preferably 1-7% by weight, very preferably 1-4% by weight, based on the entire mixture;

[0524] and / or

[0525] -One or more compounds of formula PH-1 or its sub-formulas, preferably with a total concentration in the range of 0.1-10% by weight, more preferably 1-7% by weight, very preferably 1-4% by weight, based on the entire mixture;

[0526] and / or

[0527] -One or more compounds of formula II or its sub-formulas, preferably compounds of formula IIA, IIB, IIC, IID, IIE and / or IIF, preferably with a total concentration in the range of 20-70%, more preferably 25-65%, particularly preferably 30-65%, based on the entire mixture;

[0528] and / or

[0529] -One or more compounds of formula IV or its sub-formulas, preferably compounds of formula IV-1, IV-3 and IVa-2, preferably with a total concentration in the range of 10-60% by weight, more preferably 13-55% by weight, particularly preferably 15-50% by weight, based on the entire mixture;

[0530] and / or

[0531] -One or more compounds of formula V or its sub-formulas, preferably compound of formula V-10, preferably with a total concentration in the range of 0.1-30% by weight, more preferably 0.5-25% by weight, particularly preferably 1-15% by weight, based on the entire mixture;

[0532] and / or

[0533] -One or more compounds of formula VI or its sub-formulas, preferably compound of formula VI-1, preferably with a total concentration in the range of 0.5-20% by weight, more preferably 0.75-15% by weight, particularly preferably 1-10% by weight, based on the entire mixture;

[0534] The following further preferred embodiments are listed, where the acronyms used are explained in Table B, where n and m are each independently integers from 1 to 7:

[0535] -One or more PGIGI-n-F compounds, especially PGIGI-3-F, the proportion of which is preferably 2-30% by weight, very preferably 5-20% by weight, most preferably 8-12% by weight, based on the entire mixture;

[0536] and / or

[0537] - one or more B(S)-nO-Om compounds, especially B(S)-2O-O4, B(S)-2O-O5, B(S)-2O-O6, preferably with a total concentration in the range of 2 - 20 wt%, more preferably 7 - 14 wt%, based on the entire mixture;

[0538] and / or

[0539] - one or more COB(S)-n-Om compounds, especially COB(S)-2-O4, preferably with a total concentration in the range of 2 - 20 wt%, more preferably 8 - 12 wt%, based on the entire mixture;

[0540] and / or

[0541] - one or more B-nO-Om compounds, especially B-2O-O5, preferably with a total concentration in the range of 2 - 8 wt%, very preferably 3 - 5 wt%, based on the entire mixture;

[0542] and / or

[0543] - one or more B(P)-nO-Om compounds, especially B(P)-2O-O3 and / or B(P)-2O-O4, preferably with a total concentration in the range of 0.1 - 10 wt%, more preferably 1 - 7 wt%, very preferably 1 - 4 wt%, based on the entire mixture;

[0544] and / or

[0545] - one or more B(A)-nO-Om compounds, especially B(A)-2O-O2, preferably with a total concentration in the range of 0.1 - 10 wt%, more preferably 1 - 7 wt%, very preferably 1 - 4 wt%, based on the entire mixture;

[0546] and / or

[0547] - One or more compounds Y-nO-Om, CY-n-Om, CPY-n-Om, CCY-n-Om, CCY-Vn-Om, CLY-n-Om, CLOY-n-Om, COY-n-Om, CCOY-n-Om, CCEY-n-Om, PY-n-Om, PYP-n-m and / or CAIY-n-Om, in particular Y-4O-O4, CY-3-O2, CPY-3-O2, CCY-3-O2, CCY-5-O2, CLY-3-O2, CLY-3-O3, CLY-4-O2, CLY-5-O2, CLOY-3-O2, PYP-2-3, PYP-2-4 and / or CAIY-3-O2, preferably in a total concentration in the range of 20 - 70% by weight, more preferably 25 - 65% by weight, based on the entire mixture;

[0548] and / or

[0549] - One or more compounds CC-n-m, CC-n-V, CC-n-Vm and / or CP-n-Om, preferably CC-3-4, CC-3-5, CC-3-V, CC-3-V1, CC-4-V1 and / or CP-3-O2, preferably in a total concentration in the range of 10 - 60%, more preferably 13 - 55%, particularly preferably 15 - 50%, based on the entire mixture;

[0550] and / or

[0551] - 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 - 30%, preferably 10 - 20%, based on the entire mixture;

[0552] and / or

[0553] - One or more compounds PY-n-Om and / or PY-nO-Om, in particular PY-1-O2, PY-2-O2 and / or PY-3-O2, preferably in a total concentration in the range of 5 - 40%, preferably 10 - 30%, based on the entire mixture;

[0554] and / or

[0555] - One or more compounds CPY-n-Om and / or CPY-Vn-m, in particular CPY-2-O2, CPY-3-O2 and / or CPY-5-O2, preferably at a concentration > 5%, in particular 7 - 20%, based on the entire mixture,

[0556] and / or

[0557] -One or more compounds CCY-n-Om, preferably CCY-4-O2, CCY-3-O2, CCY-3-O3, CCY-3-O1 and / or CCY-5-O2, preferably at a concentration > 3%, especially 5 - 15%, based on the entire mixture;

[0558] and / or

[0559] -One or more compounds CPY-n-Om and CY-n-Om, preferably at a concentration of 10 - 80%, based on the entire mixture,

[0560] and / or

[0561] -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 - 20%, more preferably 10 - 15%, based on the entire mixture,

[0562] and / or

[0563] -One or more compounds selected from CCH-13, CCH-23, CCH-24, CCH-25, CCH-34, CCH-35, CCH-301 and CCH-303, preferably at a total concentration of 3 - 40%, preferably 3 - 25%, based on the entire mixture,

[0564] and / or

[0565] -One or more compounds selected from CC-2-V1, CC-3-V1, CC-3-V2, CC-4-V1, CC-3-V, CC-4-V and CC-5-V, preferably at a total concentration of 3 - 40%, more preferably 5% - 30%, based on the entire mixture,

[0566] and / or

[0567] -One or more compounds CCP-n-m and / or CCP-Vn-m and / or CPP-n-m, preferably selected from CCP-3-1, CCP-V-1, CCP-V2-1 and CPP-3-2, preferably at a total concentration of 4 - 35%, preferably 5 - 25%, based on the entire mixture,

[0568] and / or

[0569] -One or more compounds CLP-n-m, CLP-n-Om and / or CLP-Vn-m, preferably selected from CLP-3-1, CLP-3-2, CLP-3-O1, CLP-3-O2 and CLP-V-1, preferably at a total concentration of 1 - 25%, preferably 2 - 15%, based on the entire mixture,

[0570] and / or

[0571] - One or more compounds selected from PYP-n-m, PGIY-n-Om and PGP-n-2V, preferably at a total concentration of 2-20%, more preferably 2-15%, most preferably 2-10%, based on the entire mixture,

[0572] and / or

[0573] - One or more compounds P P-n-m and / or P P-n-nVm, preferably selected from P P-1-3, P P-1-4, P P-1-5, P P-1-2V and P P-1-2V1, preferably at a total concentration of 1-15%, more preferably 2-10%, based on the entire mixture,

[0574] and / or

[0575] - Compound PPGU-3-F, preferably at a concentration of 0.1-3%, based on the entire mixture,

[0576] and / or

[0577] - One or more diphenylacetylene compounds, preferably at a total concentration of 1-20%, more preferably 2-12%, based on the entire mixture.

[0578] It is advantageous for the liquid crystal medium according to the invention to preferably have a nematic phase of ≤ -20 °C to ≥ 70 °C, particularly preferably ≤ -30 °C to ≥ 80 °C, very particularly preferably ≤ -40 °C to ≥ 90 °C.

[0579] The LC medium according to the invention has a clearing temperature of 70 °C or higher, preferably 95 °C or higher, for example 95-125 °C.

[0580] The expression "having a nematic phase" here means on the one hand that no smectic phase and no crystallization are observed at the corresponding temperature at low temperature and on the other hand that it does not become clear when heated from the nematic phase. The low-temperature studies are carried out in a flow viscometer at the corresponding temperature and are checked by storing in a test cell having a layer thickness corresponding to electro-optical use for at least 100 hours. If the storage stability in the corresponding test cell at -20 °C is 1000 hours or more, the LC medium is called stable at this temperature. At the temperatures of -30 °C and -40 °C, the corresponding times are 500 hours and 250 hours respectively. At high temperature, the clearing point is measured in a capillary by a conventional method.

[0581] The liquid crystal mixture preferably has a nematic phase range of at least 60 K and a flow viscosity ν of at most 30 mm 2 ·s -1 at 20 °C 20 .

[0582] 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.

[0583] The value of the birefringence Δn in the liquid crystal mixture is generally 0.07 - 0.16, preferably 0.08 - 0.15, and very preferably 0.09 - 0.14. In a preferred embodiment of the present invention, the birefringence of the LC medium is 0.075 - 0.140, preferably 0.090 - 0.138, especially 0.100 - 0.137.

[0584] The liquid crystal mixture according to the present invention has a dielectric anisotropy Δε of -1.5 to -8.0, preferably -3.0 to -6.9.

[0585] The rotational viscosity γ1 at 20 °C is preferably ≤245 mPa·s, especially ≤240 mPa·s. In a preferred embodiment, the rotational viscosity γ1 at 20 °C is ≤235 mPa·s, especially ≤230 mPa·s.

[0586] The liquid crystal medium according to the present invention has a relatively low value of the threshold voltage (V0). They are preferably 1.7 V to 3.0 V, particularly preferably ≤2.7 V and very particularly preferably ≤2.5 V.

[0587] For the present invention, unless otherwise expressly stated, the term "threshold voltage" relates to the capacitive threshold (V0), also known as the Freedericks threshold.

[0588] Furthermore, the liquid crystal medium according to the present invention has a high value of the voltage holding ratio in the liquid crystal cell.

[0589] Generally, a liquid crystal medium with a low addressing voltage or threshold voltage shows a lower voltage holding ratio than those LC media with a higher addressing voltage or threshold voltage, and vice versa.

[0590] For the present invention, the term "dielectric positive compound" means a compound having Δε > 1.5, the term "dielectric neutral compound" means those having -1.5 ≤ Δε ≤ 1.5 and the term "dielectric negative compound" means those having Δε < -1.5. Here, the dielectric anisotropy of the compound is determined by dissolving 10% of the compound in the liquid crystal host in at least one test cell and measuring the capacitance of the resulting mixture. In each case, the test cell has a layer thickness of 20 μm and has vertical and planar surface alignments at 1 kHz. The measurement voltage is generally 0.5 V - 1.0 V, but is always lower than the capacitance threshold of the respective liquid crystal mixture under investigation.

[0591] All temperature values described in the present invention are in °C.

[0592] The LC medium according to the present invention is suitable for all FFS (fringe field switching) and UB-FFS (ultra bright FFS) applications with negative Δε. The LC medium according to the present invention is also suitable for all VA-TFT (vertical alignment thin film transistor) applications, such as VAN (vertical alignment nematic), MVA (multi-domain VA), (S)-PVA (super patterned VA), ASV (advanced super view or axially symmetric VA), PSA (polymer stabilized VA) and PS-VA (polymer stabilized VA). In addition, they are also suitable for IPS (in-plane switching) applications with negative Δε.

[0593] The nematic LC medium in the display according to the present invention generally comprises two components A and B, which are themselves composed of one or more individual compounds.

[0594] Component A has a significant negative dielectric anisotropy and gives a dielectric anisotropy of the nematic phase of ≤ -0.5.

[0595] The proportion of component A is preferably 45 - 100%, especially 60 - 85%.

[0596] For component A, one or more individual compounds with a Δε value of ≤ -1.5 are preferably selected. The smaller the proportion of A in the whole mixture, the more negative this value will be.

[0597] Component B is a dielectrically neutral compound with -1.5 ≤ Δε ≤ 1.5. In addition, component B has a distinct nematogeneity and a flow viscosity at 20 °C of not more than 30 mm 2 ·s -1 and preferably not more than 25 mm 2 ·s -1 .

[0598] Those skilled in the art know a variety of suitable materials from the literature.

[0599] Particularly preferred individual compounds in component B are nematic liquid crystals with extremely low viscosity, having a flow viscosity at 20 °C of not more than 18 mm 2 ·s -1 and preferably not more than 12 mm 2 ·s -1 .

[0600] Component B is monotropically or enantiotropically nematic, without a smectic phase, and is capable of preventing the occurrence of a smectic phase in the LC medium at low to very low temperatures. For example, if various highly nematic materials are added to a smectic liquid crystal mixture, then the nematic states of these materials can be compared by suppressing the degree of reaching the smectic phase.

[0601] The mixture may also optionally contain component C, which comprises a compound having a dielectric anisotropy of Δε ≥ 1.5. These so-called positive compounds are usually present in a negative dielectric anisotropy mixture in an amount of ≤ 20 wt%, based on the entire mixture.

[0602] In addition to the compound of formula I, the compound of formula III, the compound of formula IIIA, the compound of formula BC, the compound of formula PH-1, and the compound of formula IIA, IIB, IIC, IID, and / or IIE, other components may also be present, for example, in an amount of up to 45% of the entire mixture, but preferably up to 35%, especially up to 10%.

[0603] Other components are preferably selected from nematic or nematogenic substances, particularly from known substances of the following categories: azoxybenzene, benzylideneaniline, biphenyl, terphenyl, phenyl benzoate or cyclohexyl benzoate, phenyl cyclohexanecarboxylate or cyclohexyl cyclohexanecarboxylate, phenylcyclohexane, cyclohexylbiphenyl, cyclohexylcyclohexane, cyclohexylnaphthalene, 1,4-biscyclohexylbiphenyl or cyclohexylpyrimidine, phenyl dioxane or cyclohexyl dioxane, optionally halogenated stilbene, benzyl phenyl ether, diphenylacetylene, and substituted cinnamic acid esters.

[0604] The most important compounds suitable as components of a liquid crystal phase of this type can be represented by formula R

[0605] R R1 -L-G-E-R R2 R

[0606] wherein L and E each represent a carbocyclic or heterocyclic system selected from the group consisting of: 1,4-disubstituted benzene rings and cyclohexane rings, 4,4'-disubstituted biphenyls, phenylcyclohexane and cyclohexylcyclohexane systems, 2,5-disubstituted pyrimidines and 1,3-dioxane rings, 2,6-disubstituted naphthalenes, dihydronaphthalenes and tetrahydronaphthalenes, quinazolines and tetrahydroquinazolines,

[0607] G represents -CH=CH- -N(O)=N-

[0608] -CH=CQ- -CH=N(O)-

[0609] -C≡C- -CH2-CH2-

[0610] -CO-O- -CH2-O-

[0611] -CO-S- -CH2-S-

[0612] -CH=N- -COO-Phe-COO-

[0613] -CF2O- -CF=CF-

[0614] -OCF2- -OCH2-

[0615] -(CH2)4- -(CH2)3O-

[0616] or a C-C single bond, Q represents a halogen, preferably chlorine or -CN, and R R1 and R R2 each represents an alkyl, alkenyl, alkoxy, alkoxyalkyl or alkoxycarbonyloxy group having at most 18 carbon atoms, preferably at most 8 carbon atoms, or alternatively one of these groups represents CN, NC, NO2, NCS, CF3, SF5, OCF3, F, Cl or Br.

[0617] 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 variations of the proposed substituents are also common. Many such substances or their mixtures are also commercially available. All these substances can be prepared by methods known from the literature.

[0618] It goes without saying for a person skilled in the art that the VA, IPS or FFS mixtures according to the invention may also contain compounds in which, for example, H, N, O, Cl and F are replaced by corresponding isotopes.

[0619] The LC medium preferably has a nematic LC phase.

[0620] The LC medium may also contain one or more stabilizers to prevent, for example, the undesired spontaneous polymerization of RM during storage or transport. Suitable types and amounts of stabilizers are known to a person skilled in the art and are described in the literature. Particularly suitable are, for example, the commercially available stabilizers of the series (Ciba AG), such as 1076. If stabilizers are used, their proportion, based on the total amount of RM or the polymerizable components (component A), is preferably 10 - 50,000 ppm, particularly preferably 50 - 5,000 ppm.

[0621] In a preferred embodiment, the LC medium contains one or more chiral dopants, preferably at a concentration of 0.01 - 1 wt%, very preferably 0.05 - 0.5 wt%. The chiral dopants are preferably selected from the compounds of Table C below, very preferably R- or S-1011, R- or S-2011, R- or S-3011, R- or S-4011 and R- or S-5011.

[0622] In another preferred embodiment, the LC medium contains a racemate of one or more chiral dopants, which is preferably selected from the chiral dopants mentioned in the previous paragraph.

[0623] In another preferred embodiment of the present invention, the LC medium contains one or more other stabilizers.

[0624] The preferred stabilizers are selected from compounds of formula H

[0625]

[0626] wherein

[0627] Ar represents an aromatic or heteroaromatic hydrocarbon group having 4 - 40 C atoms, preferably 6 - 30 C atoms;

[0628] Sp represents a spacer group;

[0629] R S represents H, an alkyl group having 1 - 12 C atoms or an alkenyl group having 2 - 12 C atoms;

[0630] Z S represents -O-, -C(O)O-, -(CH2) z - or -(CH2) z O- or a single bond;

[0631] HA represents

[0632] R H represents H, O · , CH3, OH or OR S , preferably H or O · ;

[0633] R S1 , R S2 , R S3 and R S4 are the same or different and represent an alkyl group having 1 - 6 C atoms, preferably having 1 - 3 C atoms, very preferably CH3;

[0634] G represents H or R S or the group Z S -HA;

[0635] z is an integer from 1 - 6; and

[0636] q is 3 or 4.

[0637] Compounds of formula H are described in EP 3354710 A1 and EP 3354709 A1.

[0638] Preferred compounds of formula H are selected from formula H-1, H-2 and H-3:

[0639]

[0640]

[0641] 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, where one or more non-adjacent -CH2- groups may be replaced by -O-.

[0642] Preferred compounds of formula H-1 are those of formula H-1-1:

[0643]

[0644] 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.

[0645] Very preferred compounds of formula H-1-1 are those of formula H-1-1-1:

[0646]

[0647] Preferred compounds of formula H-2 are those of formula H-2-1:

[0648]

[0649] wherein R H has the meaning given above and preferably represents H or O · , and

[0650] n2 is the same or different, preferably the same, each time it appears and is an integer from 1 to 12, preferably 2, 3, 4, 5 or 6, very preferably 3, and R S is the same or different, preferably the same, each time it appears and represents an alkyl group having 1 to 6 C atoms, preferably n-butyl.

[0651] Very preferred compounds of formula H-2-1 are those of formula H-2-1-1:

[0652]

[0653] Preferred compounds of formula H-3 are selected from formula H-3-1:

[0654]

[0655] wherein Sp and R H have the meaning 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.

[0656] Further preferred stabilizers are selected from the formulas ST-1 to ST-18:

[0657]

[0658]

[0659]

[0660]

[0661]

[0662] wherein

[0663] R ST represents H, an alkyl or alkoxy group having 1 to 15 C atoms, wherein in addition, one or more CH2 groups may each independently of one another be replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-,

[0664]

[0665] -O-, -CO-O-, -O-CO- in such a way that the O atoms are not directly connected to each other, and wherein furthermore, one or more H atoms may be replaced by halogen,

[0666] in each occurrence, represents the same or differently

[0667] 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,

[0668] L 1 and L 2 each independently of one another represents F, Cl, CH3, CF3 or CHF2,

[0669] p represents 0, 1 or 2,

[0670] q represents 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0671] Preferred compounds of formula ST are those selected from formulae ST-1, ST-3, ST-8, ST-9, ST-12, ST-16, ST-17 and ST-18, and in particular:

[0672]

[0673] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3

[0674]

[0675] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3

[0676]

[0677] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 1 or 7

[0678]

[0679]

[0680] where q = 8.

[0681]

[0682]

[0683] In the compound of formula ST-2a, n preferably represents 7.

[0684] Very preferred stabilizers are compounds selected from formulae ST-2a-1, ST-3a-1, ST-3a-2, ST-3b-1, ST-3b-2, ST-3c-1, ST-7, ST-8-1, ST-9-1 and ST-12:

[0685]

[0686]

[0687] In another preferred embodiment, the LC medium comprises one or more stabilizers selected from Table D below.

[0688] The proportion of stabilizer in the LC medium is preferably 10 - 500 ppm, very preferably 20 - 100 ppm.

[0689] The LC medium according to the present invention may additionally contain one or more other components or additives, preferably selected from the following list, including but not limited to comonomers, chiral dopants, polymerization initiators, inhibitors, stabilizers, surfactants, wetting agents, lubricants, dispersants, water repellents, binders, flow improvers, defoamers, degassing agents, diluents, reactive diluents, auxiliaries, colorants, dyes, pigments, and nanoparticles.

[0690] In addition, for example, 0 to 15% by weight of a dichroic dye can be added to the LC medium, and in addition, nanoparticles, conductive salts, preferably complex salts of ethyl dimethyldodecyl 4 - hexyloxybenzoate, tetrabutyltetraphenylborate ammonium, or crown ethers (see, for example, Haller et al., Mol. Cryst. Liq. Cryst. 24 , 249 - 258 (1973)) can be used to improve conductivity, or substances can be added to modify the dielectric anisotropy, viscosity, and / or alignment of the nematic phase. Substances of this type are described, for example, in DE - A22 09 127, 2240 864, 23 21 632, 23 38 281, 24 50 088, 26 37430, and 28 53 728.

[0691] The individual components of the above - listed preferred embodiments of the LC medium according to the present invention are known, or the methods for preparing them can be readily obtained by those skilled in the relevant art from the prior art, since they are based on standard methods described in the literature. For example, the corresponding compounds of formula CY are described in EP - A - 0 364 538. The corresponding compounds of formula IV are described in DE - A - 26 36684 and DE - A - 33 21 373, for example.

[0692] The LC medium that can be used according to the present invention is prepared by a conventional method per se, for example, by mixing one or more of the above - mentioned compounds with one or more polymerizable compounds as defined above, and optionally with other liquid crystal compounds and / or additives. Generally, the desired amounts of 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 present invention also relates to a method for preparing the LC medium according to the present invention.

[0693] It goes without saying for those skilled in the art that the LC medium according to the present invention can also contain, for example, compounds in which H, N, O, Cl, F are replaced by the corresponding isotopes such as deuterium.

[0694] 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.

[0695] For the present invention and in the following examples, the structures of the liquid-crystal compounds are indicated with the aid of abbreviations which, unless otherwise indicated, are converted into chemical formulae according to the following Tables A.1 to A.3. 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 an alkylene group, each having n, m and 1 C atoms in each case. Preferably, n, m and 1 are independently 1, 2, 3, 4, 5, 6 or 7. Table A.1 shows the codes for the ring elements of the compound core, Table A.2 lists the bridging units, and Table A.3 lists the symbolic meanings of the left-hand and right-hand end groups of the molecule. The abbreviations consist of the code for the ring element with the optional linking group, followed by the first hyphen and the left-hand end group code, and the second hyphen and the right-hand end group code.

[0696] Table A.1 Ring Elements

[0697]

[0698]

[0699]

[0700]

[0701] Table A.2 Bridging Units

[0702]

[0703] Table A.3 End Groups

[0704]

[0705]

[0706] Where n and m are each integers, and the three dots "..." are placeholders for other abbreviations from the table.

[0707] Table B shows illustrative structures of compounds and their corresponding abbreviations, which compounds are preferred co-compounds of the mixture concept claimed in the present invention.

[0708] Table B

[0709] In Table B, n, m, k and l are each independently of one another integers, preferably 1 - 9, more preferably 1 - 7, k and l can also be 0, preferably 0 - 4, more preferably 0 - 2 or 0 or 2, most preferably 2, n is preferably 1, 2, 3, 4 or 5, or 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, or 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 .

[0710]

[0711]

[0712]

[0713]

[0714]

[0715]

[0716]

[0717]

[0718]

[0719]

[0720]

[0721]

[0722]

[0723]

[0724]

[0725]

[0726]

[0727]

[0728]

[0729]

[0730]

[0731]

[0732] In a preferred embodiment of the present invention, the LC medium according to the present invention comprises one or more compounds selected from Table B.

[0733] Table C

[0734] Table C shows the possible chiral dopants that can be added to the LC medium of the present invention.

[0735]

[0736]

[0737] The LC medium preferably comprises 0 - 10% by weight, in particular 0.01 - 5% by weight, and particularly preferably 0.1 - 3% by weight of the dopant. The LC medium preferably comprises one or more dopants selected from the compounds of Table C.

[0738] Table D

[0739] Table D shows the possible stabilizers that can be added to the LC medium of the present invention. Where 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.

[0740]

[0741]

[0742]

[0743]

[0744]

[0745]

[0746]

[0747] The LC medium preferably contains 0 - 10 wt%, especially 1 ppm - 5 wt%, and particularly preferably 1 ppm - 1 wt% of a stabilizer. The LC medium preferably contains one or more stabilizers selected from the compounds in Table D.

[0748] Table E

[0749] Table E shows exemplary reactive mesogenic compounds that can be used in the LC medium of the present invention.

[0750]

[0751]

[0752]

[0753]

[0754]

[0755]

[0756]

[0757]

[0758]

[0759]

[0760]

[0761]

[0762]

[0763]

[0764]

[0765]

[0766]

[0767]

[0768]

[0769] In a preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds, preferably selected from the polymerizable compounds of the formulas RM-1 to RM-182. Among these compounds, 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. Detailed Description of the Invention

[0770] Examples

[0771] The following examples illustrate the invention without limiting it. However, they show the person skilled in the art the concept of the preferred mixtures and the preferred compounds used and their respective concentrations and their combinations with one another. In addition, the examples illustrate the properties and combinations of properties that can be obtained.

[0772] In addition, the following abbreviations and symbols are used:

[0773] V0 denotes the threshold voltage at 20 °C, capacitive [V],

[0774] n e denotes the extraordinary refractive index at 20 °C and 589 nm,

[0775] n o denotes the ordinary refractive index at 20 °C and 589 nm,

[0776] Δn denotes the optical anisotropy at 20 °C and 589 nm,

[0777] ε ⊥ denotes the dielectric constant perpendicular to the director at 20 °C and 1 kHz,

[0778] ε || denotes the dielectric constant parallel to the director at 20 °C and 1 kHz,

[0779] Δε denotes the dielectric anisotropy at 20 °C and 1 kHz,

[0780] cl.p., T(N,I) denotes the clearing point [°C],

[0781] γ1 represents the rotational viscosity [mPa·s] at 20°C,

[0782] K1 represents the elastic constant at 20°C, "tilt" deformation [pN],

[0783] K2 represents the elastic constant at 20°C, "twist" deformation [pN],

[0784] K3 represents the elastic constant at 20°C, "bend" deformation [pN].

[0785] K avg represents the average elastic constant [pN] at 20°C, which is defined herein as K avg ≡( 3 / 2K1 + K3) / 3 ≈ (K1 + K2 + K3) / 3,

[0786] LTS represents the low-temperature stability of the phase, determined in a test cell,

[0787] VHR represents the voltage holding ratio.

[0788] Unless otherwise expressly indicated, all concentrations in this application are given as weight percentages and are relative to the respective total mixture, which includes all solid or liquid crystal components (without solvent).

[0789] Unless otherwise specified, all temperature values indicated in this application, such as the melting point T(C,N), the transition from the smectic phase (S) to the nematic phase (N) T(S,N), and the clearing point T(N,I), are expressed in degrees Celsius (°C). M.p. represents the melting point, and cl.p. = clearing point. In addition, C = crystalline state, N = nematic phase, S = smectic phase, and I = isotropic phase. The data between these symbols represent the transition temperatures.

[0790] 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.

[0791] The term "threshold voltage" used in this invention refers to the capacitive threshold (V0), which is also referred to as the Freedericks threshold, unless otherwise specified. In the examples, the optical threshold is also given as usual for a relative contrast of 10% (V 10 ).

[0792] Unless otherwise specified, the method of polymerizing polymerizable compounds in a PSA display as described in the context is carried out at a temperature at which the LC medium exhibits a liquid crystal phase, preferably a nematic phase, and most preferably at room temperature.

[0793] Unless otherwise specified, the method of preparing test cells and measuring their electro-optical and other properties is carried out by the methods described below or similar methods.

[0794] The PSVA display or PSVA test cell for photopolymerization and measuring tilt angles etc. consists of two planar parallel glass outer plates spaced 3 - 4 μm apart. Unless otherwise specified, each of the outer plates has an electrode layer on the inner side and a polyimide alignment layer on top, where the two polyimide layers are rubbed antiparallel to each other and result in homeotropic alignment of liquid crystal molecules. The SAVA display or test cell has the same structure, but one or both of the polyimide layers are omitted.

[0795] The polymerizable compounds are polymerized in the display or test cell by irradiating with UV light of a defined intensity for a predetermined time while applying a voltage (usually 10V - 30V alternating current, 1kHz) to the display.

[0796] The tilt angle is measured using Axometrics' Mueller Matrix Polarimeter “AxoScan”. Small values (i.e., large deviations from the 90° angle) correspond to large tilts here.

[0797] 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 uniform orientation, which corresponds to the molecular long axis in the case of rod-shaped, uniaxial positive birefringent LC molecules.

[0798] Example 1

[0799] The nematic LC mixture N1 is formulated as follows.

[0800]

[0801]

[0802] 150 ppm of stabilizer ST-3a-1 is added to the mixture N1.

[0803]

[0804] Example 2

[0805] The nematic LC mixture N2 is formulated as follows.

[0806]

[0807] Add 100 ppm of stabilizer H-1-1-1 to mixture N2.

[0808]

[0809] Example 3

[0810] Prepare the nematic LC mixture N3 as follows.

[0811]

[0812] Add 100 ppm of stabilizer ST-3b-1 and 50 ppm of stabilizer ST-3a-1 to mixture N3.

[0813]

[0814] Example 4

[0815] Prepare the nematic LC mixture N4 as follows.

[0816]

[0817] Add 50 ppm of stabilizer H-2-1-1 and 50 ppm of stabilizer ST-3a-1 to mixture N4.

[0818]

[0819] Example 5

[0820] Prepare the nematic LC mixture N5 as follows.

[0821]

[0822]

[0823] Add 100 ppm of stabilizer ST-8-1 and 50 ppm of stabilizer ST-3a-1 to mixture N5.

[0824]

[0825] Example 6

[0826] Prepare the nematic LC mixture N6 as follows.

[0827]

[0828]

[0829] Add 50 ppm of stabilizer ST-9-1 and 50 ppm of stabilizer ST-3a-1 to mixture N6.

[0830]

[0831] Example 7

[0832] Prepare nematic LC mixture N7 as follows.

[0833]

[0834] Add 50 ppm of stabilizer ST-12 and 50 ppm of stabilizer ST-3a-1 to mixture N7.

[0835]

[0836] Example 8

[0837] Prepare nematic LC mixture N8 as follows.

[0838]

[0839] Add 150 ppm of stabilizer ST-3a-2 to mixture N8.

[0840]

[0841] Example 9

[0842] Prepare nematic LC mixture N9 as follows.

[0843]

[0844]

[0845] Add 100 ppm of stabilizer ST-3b-2 and 50 ppm of stabilizer ST-3a-1 to mixture N9.

[0846]

[0847] Example 10

[0848] Prepare nematic LC mixture N10 as follows.

[0849]

[0850] Add 100 ppm of stabilizer ST-7 and 50 ppm of stabilizer ST-3a-2 to mixture N10.

[0851]

[0852] Example 11

[0853] Prepare the nematic LC mixture N11 as follows.

[0854]

[0855] Add 100 ppm of stabilizer H-1-1-1 and 50 ppm of stabilizer ST-3a-2 to the mixture N11.

[0856] Example 12

[0857] Prepare the nematic LC mixture N12 as follows.

[0858]

[0859]

[0860] Add 150 ppm of stabilizer ST-3a-1 to the mixture N12.

[0861] Example 13

[0862] Prepare the nematic LC mixture N13 as follows.

[0863]

[0864] Add 100 ppm of stabilizer ST-3b-1 and 50 ppm of stabilizer ST-3a-2 to the mixture N13.

[0865] Example 14

[0866] Prepare the nematic LC mixture N14 as follows.

[0867]

[0868] Add 50 ppm of stabilizer H-2-1-1 and 50 ppm of stabilizer ST-3a-1 to the mixture N14.

[0869] Example 15

[0870] Prepare the nematic LC mixture N15 as follows.

[0871]

[0872]

[0873] Add 100 ppm of stabilizer ST-8-1 and 50 ppm of stabilizer ST-3a-2 to mixture N15.

[0874] Example 16

[0875] Prepare nematic LC mixture N16 as follows.

[0876]

[0877] Add 50 ppm of stabilizer ST-9-1 and 50 ppm of stabilizer ST-3a-1 to mixture N16.

[0878] Example 17

[0879] Prepare nematic LC mixture N17 as follows.

[0880]

[0881] Add 50 ppm of stabilizer ST-12 to mixture N17.

[0882] Example 18

[0883] Prepare nematic LC mixture N18 as follows.

[0884]

[0885] Add 150 ppm of stabilizer ST-3a-2 to mixture N18.

[0886] Example 19

[0887] Prepare nematic LC mixture N19 as follows.

[0888]

[0889]

[0890] Add 150 ppm of stabilizer ST-3b-2 to mixture N19.

[0891] Example 20

[0892] Prepare nematic LC mixture N20 as follows.

[0893]

[0894] Add 50 ppm of stabilizer ST-7 to mixture N20.

[0895] Example 21

[0896] Prepare the nematic LC mixture N21 as follows.

[0897]

[0898]

[0899] Add 100 ppm of the stabilizer H-1-1-1 to the mixture N21.

[0900] Example 22

[0901] Prepare the nematic LC mixture N22 as follows.

[0902]

[0903] Add 150 ppm of the stabilizer ST-3a-1 to the mixture N22.

[0904] Example 23

[0905] Prepare the nematic LC mixture N23 as follows.

[0906]

[0907]

[0908] where B(S)-4O-O1(c5) is

[0909]

[0910] Add 150 ppm of the stabilizer ST-3b-1 to the mixture N23.

[0911] Example 24

[0912] Prepare the nematic LC mixture N24 as follows.

[0913]

[0914] where B(S)-1V1O-O1(c5) is

[0915]

[0916] Add 50 ppm of the stabilizer H-2-1-1 to the mixture N24.

[0917] Example 25

[0918] Prepare the nematic LC mixture N25 as follows.

[0919]

[0920]

[0921] Add 100 ppm of stabilizer ST-8-1 to mixture N25.

[0922] Example 26

[0923] Prepare nematic LC mixture N26 as follows.

[0924]

[0925] Add 50 ppm of stabilizer ST-9-1 to mixture N26.

[0926] Example 27

[0927] Prepare nematic LC mixture N27 as follows.

[0928]

[0929]

[0930] Add 50 ppm of stabilizer ST-12 to mixture N27.

[0931] Example 28

[0932] Prepare nematic LC mixture N28 as follows.

[0933]

[0934] where PYP-2-(c5) is

[0935]

[0936] Add 150 ppm of stabilizer ST-3a-2 to mixture N28.

[0937] Example 29

[0938] Prepare nematic LC mixture N29 as follows.

[0939]

[0940]

[0941] where PYP-2-1(c3) is

[0942]

[0943] Add 150 ppm of stabilizer ST-3b-2 to mixture N29.

[0944] Example 30

[0945] Prepare nematic LC mixture N30 as follows.

[0946]

[0947] where CCP-1V2-1 is

[0948]

[0949] Add 100 ppm of stabilizer ST-7 to mixture N30.

[0950] Example 31

[0951] Prepare nematic LC mixture N31 as follows.

[0952]

[0953]

[0954] Add 100 ppm of stabilizer H-1-1-1 to mixture N31.

[0955] Example 32

[0956] Prepare nematic LC mixture N32 as follows.

[0957]

[0958] Add 150 ppm of stabilizer ST-3a-1 to mixture N32.

[0959] Example 33

[0960] Prepare nematic LC mixture N33 as follows.

[0961]

[0962]

[0963] Add 150 ppm of stabilizer ST-3b-1 to mixture N33.

[0964] Example 34

[0965] Prepare nematic LC mixture N34 as follows.

[0966]

[0967] Add 50 ppm of stabilizer H-2-1-1 to mixture N34.

[0968] Example 35

[0969] Prepare nematic LC mixture N35 as follows.

[0970]

[0971] Add 100 ppm of stabilizer ST-8-1 and 50 ppm of stabilizer ST-3a-1 to mixture N35.

[0972] Example 36

[0973] Prepare nematic LC mixture N36 as follows.

[0974]

[0975] Add 50 ppm of stabilizer ST-9-1 and 50 ppm of stabilizer ST-3a-2 to mixture N36.

[0976] Example 37

[0977] Prepare nematic LC mixture N37 as follows.

[0978]

[0979] Add 50 ppm of stabilizer ST-12 and 50 ppm of stabilizer ST-3a-1 to mixture N37.

[0980] Example 38

[0981] Prepare nematic LC mixture N38 as follows.

[0982]

[0983]

[0984] Add 150 ppm of stabilizer ST-3a-2 to mixture N38.

[0985] Example 39

[0986] Prepare nematic LC mixture N39 as follows.

[0987]

[0988] Add 150 ppm of stabilizer ST-3b-2 and 50 ppm of stabilizer ST-3a-2 to mixture N39.

[0989] Example 40

[0990] Prepare the nematic LC mixture N40 as follows.

[0991]

[0992] Add 100 ppm of stabilizer ST-7 and 50 ppm of stabilizer ST-3a-1 to mixture N40.

[0993] Example 41

[0994] Prepare the nematic LC mixture N41 as follows.

[0995]

[0996] Add 100 ppm of stabilizer H-1-1-1 and 50 ppm of stabilizer ST-3a-2 to mixture N41.

[0997] Example 42

[0998] Prepare the nematic LC mixture N42 as follows.

[0999]

[1000] Add 150 ppm of stabilizer ST-3a-1 to mixture N42.

[1001] Example 43

[1002] Prepare the nematic LC mixture N43 as follows.

[1003]

[1004]

[1005] Add 100 ppm of stabilizer ST-3b-1 and 50 ppm of stabilizer ST-3a-1 to mixture N43.

[1006] Example 44

[1007] Prepare the nematic LC mixture N44 as follows.

[1008]

[1009] Add 50 ppm of stabilizer H-2-1-1 and 50 ppm of stabilizer ST-3a-2 to mixture N44.

[1010] Example 45

[1011] Prepare the nematic LC mixture N45 as follows.

[1012]

[1013] Add 100 ppm of stabilizer ST-8-1 and 50 ppm of stabilizer ST-3a-1 to mixture N45.

[1014] Example 46

[1015] Prepare a polymerizable mixture by adding 0.3% of the polymerizable compound RM-171 to the mixture of Example 1.

[1016]

[1017] Example 47

[1018] Prepare a polymerizable mixture by adding 0.3% of the polymerizable compound RM-1 to the mixture of Example 2.

[1019]

[1020] Example 48

[1021] Prepare a polymerizable mixture by adding 0.3% of the polymerizable compound RM-35 to the mixture of Example 3.

[1022]

[1023] Example 49

[1024] Prepare a polymerizable mixture by adding 0.3% of the polymerizable compound RM-172 to the mixture of Example 4.

[1025]

[1026] Example 50

[1027] Prepare a polymerizable mixture by adding 0.4% of the polymerizable compound RM-64 to the mixture of Example 5.

[1028]

[1029] Example 51

[1030] The nematic LC mixture N51 was prepared as follows.

[1031]

[1032] 100 ppm of stabilizer ST-8-1 and 50 ppm of stabilizer ST-3a-1 were added to the mixture N51.

[1033] Example 52

[1034] The nematic LC mixture N52 was prepared as follows.

[1035]

[1036] 50 ppm of stabilizer H-2-1-1 and 50 ppm of stabilizer ST-3a-2 were added to the mixture N52.

[1037] Example 53

[1038] The nematic LC mixture N53 was prepared as follows.

[1039]

[1040] 100 ppm of stabilizer ST-3b-1 and 50 ppm of stabilizer ST-3a-1 were added to the mixture N53.

[1041] Example 54

[1042] The nematic LC mixture N54 was prepared as follows.

[1043]

[1044] 300 ppm of stabilizer ST-3a were added to the mixture N54.

[1045] Example 55

[1046] The nematic LC mixture N55 was prepared as follows.

[1047]

[1048]

[1049] 300 ppm of stabilizer ST-3a were added to the mixture N55.

[1050] Example 56

[1051] The nematic LC mixture N56 was prepared as follows.

[1052]

[1053] 100 ppm of stabilizer H-1-1-1 and 50 ppm of stabilizer ST-3a-2 were added to mixture N56.

[1054] Example 57

[1055] The nematic LC mixture N57 was prepared as follows.

[1056]

[1057]

[1058] 50 ppm of stabilizer ST-12 and 50 ppm of stabilizer ST-3a-1 were added to mixture N57.

[1059] Example 58

[1060] The nematic LC mixture N58 was prepared as follows.

[1061]

[1062] 150 ppm of stabilizer ST-3a-2 was added to mixture N58.

[1063] Example 59

[1064] The nematic LC mixture N59 was prepared as follows.

[1065]

[1066]

[1067] 150 ppm of stabilizer ST-3b-2 and 50 ppm of stabilizer ST-3a-2 were added to mixture N59.

[1068] Example 60

[1069] The nematic LC mixture N60 was prepared as follows.

[1070]

[1071] 100 ppm of stabilizer ST-7 and 50 ppm of stabilizer ST-3a-1 were added to mixture N60.

[1072] Example 61

[1073] The nematic LC mixture N61 was prepared as follows.

[1074]

[1075] 50 ppm of stabilizer ST-7 and 100 ppm of stabilizer ST-3a-1 were added to the mixture N61.

[1076] Example 62

[1077] The nematic LC mixture N62 was prepared as follows.

[1078]

[1079] 4000 ppm of stabilizer ST-16 were added to the mixture N62.

[1080] Example 63

[1081] The nematic LC mixture N63 was prepared as follows.

[1082]

[1083] 100 ppm of stabilizer ST-3b-1 and 50 ppm of stabilizer ST-3a-1 were added to the mixture N63.

[1084] Example 64

[1085] The nematic LC mixture N64 was prepared as follows.

[1086]

[1087] 50 ppm of stabilizer H-2-1-1 and 50 ppm of stabilizer ST-3a-2 were added to the mixture N64.

[1088] Example 65

[1089] The nematic LC mixture N65 was prepared as follows.

[1090]

[1091] 100 ppm of stabilizer ST-8-1 and 50 ppm of stabilizer ST-3a-1 were added to the mixture N65.

[1092] Example 66

[1093] The nematic LC mixture N66 was prepared as follows.

[1094]

[1095] Add 50 ppm of stabilizer ST-9-1 and 50 ppm of stabilizer ST-3a-2 to mixture N66.

[1096] Example 67

[1097] Prepare nematic LC mixture N67 as follows.

[1098]

[1099] Add 300 ppm of stabilizer ST-3a to mixture N67.

[1100] Example 68

[1101] Prepare nematic LC mixture N68 as follows.

[1102]

[1103]

[1104] Add 150 ppm of stabilizer ST-3a-2 to mixture N68.

[1105] Example 69

[1106] Prepare nematic LC mixture N69 as follows.

[1107]

[1108] Add 300 ppm of stabilizer ST-3a to mixture N69.

Claims

1. A liquid crystal medium comprising one or more compounds selected from the group consisting of formula III and / or formula IIIA and / or formula BC and / or formula PH-1 and One or more compounds of formula I in R 11 , R 31 , R 32 , R 81 and R 82 each independently of one another represents H, alkyl or alkoxy having 1 to 15 C atoms, wherein one or more -CH2- groups in these radicals may each independently of one another be abbreviated in such a way that the O atoms are not directly connected to one another -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO-, and wherein one or more H atoms may be replaced by halogen, X represents F, Cl, OCF3 or OCHF2, A 3 Each occurrence represents independently of each other a) 1,4-cyclohexylene or 1,4-cyclohexenylene, 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, piperidine-1,4-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, wherein the radicals a), b) and c) are optionally mono- or polysubstituted by halogen atoms, n represents 0, 1 or 2, Z 3 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, L 11 , L 12 , L 31 and L 32 each independently represents F, Cl, CF3 or CHF2, and Y 1 , Y 2 , Y 3 , Y 4 Each independently of one another represents H, F, Cl, CF3, CHF2, CH3 or OCH3.

2. A liquid crystal medium according to claim 1, wherein the medium comprises one or more compounds selected from the group consisting of compounds of formula III-1, III-6 and / or IIIA-1 The radicals occurring therein have the same meanings as given under formulae III and IIIA.

3. A liquid-crystalline medium according to any one of claims 1 or 2, wherein the medium comprises one or more compounds selected from the group consisting of formulae IIA, IIB, IIC, IID, IIE and IIF, where the radicals, identical or different on each occurrence and independently of one another, have the following meanings: R 21 , R 22 is H, alkyl, alkoxy or alkenyl with 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 groups can be replaced by -O-, -S-, -C≡C-, -CF2O-, -OCF2-, -OC-O-, -O-CO ... Instead, 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.

4. A liquid-crystalline medium according to any one of claims 1 to 3, wherein the medium comprises one or more compounds of the formula IV in R 41 represents an unsubstituted alkyl group having 1 to 7 C atoms, or a cycloalkyl group having 3 to 6 C atoms or an unsubstituted alkenyl group having 2 to 7 C atoms, and R 42 It represents an unsubstituted alkyl group having 1 to 7 C atoms, a cycloalkyl group having 3 to 6 C atoms, an unsubstituted alkoxy group having 1 to 6 C atoms, or an unsubstituted alkenyl group having 2 to 7 C atoms.

5. Liquid-crystalline medium according to claim 4, wherein the medium comprises one or more compounds of the formula IV-1 and IV-3, in alkyl and alkyl * independently of one another represent an alkyl group having 1 to 7 C atoms or a cycloalkyl group having 3 to 6 C atoms, and Alkenyl represents alkenyl having 2-7 C atoms.

6. Liquid-crystalline medium according to claim 4, wherein the medium comprises one or more compounds of the formula IVa-2, in alkyl and alkyl * Independently of one another represent straight-chain alkyl having 1 to 6 C atoms or cycloalkyl having 3 to 6 C atoms.

7. A liquid-crystalline medium according to any one of claims 1 to 6, wherein the medium comprises one or more compounds of the formula V in R 51 and R 52 represents an alkyl group having 1 to 7 C atoms, or a cycloalkyl group having 3 to 6 C atoms, an alkoxy group having 1 to 7 C atoms, or an alkoxyalkyl group, an alkenyl group or an alkenyloxy group having 2 to 7 C atoms, Same or different Z 51 ,Z 52 each independently represents -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, and n is 1 or 2; wherein one or more compounds of formula V are different from compounds of formula I. 8 . The liquid-crystalline medium according to claim 1 , wherein the medium comprises one or more compounds of the formulae VI-1 to VI-22. 9 . The liquid-crystalline medium according to claim 1 , wherein the medium comprises one or more compounds of the formulae VII-1 to VII-9.

10. Liquid-crystalline medium according to any one of claims 1 to 9, wherein the medium comprises one or more compounds of the formulae CR and PH-2. 11 . The liquid-crystalline medium according to claim 1 , wherein the medium additionally comprises one or more additives selected from stabilizers, chiral dopants, polymerization initiators and self-aligning additives. 12 . A liquid crystal display comprising a liquid crystal medium according to claim 1 .

13. The display according to claim 12, wherein: The display is VA, PS-VA, FFS, PS-FFS, UB-FFS, UBplus, IPS, PS-IPS or UV 2 A display.

14. Use of a liquid-crystalline medium according to any one of claims 1 to 11 in energy-saving LC displays.

15. A process for preparing a liquid-crystalline medium according to any one of claims 1 to 11, comprising the step of mixing one or more compounds of the formulae I and III and / or IIIA with one or more compounds selected from the group consisting of formulae II and / or IV, optionally with other LC compounds and / or additives. 16 . The liquid-crystalline medium according to claim 1 , wherein the medium comprises one or more tolan compounds.

Images