Liquid crystal medium

Abstract

The present invention relates to liquid crystal (LC) media and liquid crystal displays (LCD) comprising these media, and to AR / VR headphones or displays, in particular energy saving displays addressed by an active matrix, in particular LC displays of the type TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, SA-HB-FFS, SA-XB-FFS, polymer stabilized SA-HB-FFS, polymer stabilized SA-XB-FFS, positive VA or positive PS-VA. The media have improved long-term stability at lower temperatures and are well suited for automotive and outdoor applications.

Description

Technical Field

[0001] The present invention relates to liquid crystal (LC) media and energy-saving liquid crystal displays (LCDs) comprising these media, in particular high-contrast gaming displays and AR / VR headsets or displays addressed by active matrix, especially TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, SA-HB-FFS, SA-XB-FFS, polymer-stabilized SA-HB-FFS, polymer-stabilized SA-XB-FFS, positive VA or positive PS-VA type LC displays. In a preferred embodiment, the liquid crystal medium has a positive dielectric anisotropy. Background Art

[0002] In many fields, liquid crystal displays (LCDs) are used to display information. LCDs are used both for direct-view displays and for projection-type displays. The electro-optic modes used are, for example, the twisted nematic (TN), super-twisted nematic (STN), optically compensated bend (OCB) and electrically controlled birefringence (ECB) modes and their various variants, as well as other modes. All of these modes utilize an electric field generated substantially perpendicular to the substrate and the LC layer.

[0003] In addition to these modes, there are also electro-optic modes that utilize an electric field substantially parallel to the substrate or the LC layer. For example, WO91 / 10936 discloses an LC display in which an electrical signal is generated in such a way that the electric field has an effective component parallel to the LC layer, and which has since been known as an "in-plane switching" (IPS) display. The principle of operating such a display is described, for example, by R.A. Soref in the Journal of Applied Physics, Volume 45, Number 12, pages 5466-5468 (1974).

[0004] An IPS display comprises a liquid crystal layer between two substrates with planar alignment, where two electrodes are arranged only on one of the two substrates and preferably have an interdigital comb-like structure. When a voltage is applied to the electrodes, an electric field with an effective component parallel to the liquid crystal layer is generated between the electrodes. This causes the liquid crystal molecules to reorient in the layer plane.

[0005] For example, EP0588568 discloses various possible forms for electrode design and addressing of IPS displays. DE19824137 likewise describes various embodiments of such IPS displays.

[0006] Liquid crystal materials for this type of IPS display are described, for example, in DE19528104.

[0007] In addition, so-called "fringe field switching" (FFS) displays have been reported (see, in particular, S.H. Jung et al., Jpn. J. Appl. Phys., Vol. 43, No. 3, 2004, 1028), which include two electrodes on the same substrate, one of which is structured in a comb-like manner and the other is unstructured. Thereby, a strong so-called "fringe field", i.e., a strong electric field near the electrode edges, and an electric field with a strong vertical component and a strong horizontal component throughout the cell are generated. FFS displays have a low contrast viewing angle dependence. FFS displays typically include a liquid crystal medium having a positive dielectric anisotropy and an alignment layer, usually made of polyimide, which provides planar alignment for the molecules of the liquid crystal medium.

[0008] Liquid crystal displays with IPS and FFS electro-optical modes are particularly suitable for modern desktop monitors, televisions and multimedia applications. The liquid crystal medium according to the present invention is preferably used for this type of display. Generally, a dielectric positive liquid crystal medium with a rather low dielectric anisotropy value is used in FFS displays, but in some cases, a liquid crystal medium with a dielectric anisotropy of only about 3 or even less is also used in IPS displays.

[0009] Further improvements have been achieved by the HB-FFS mode. One of the unique features of the HB-FFS mode compared to traditional FFS technology is its ability to achieve higher transmittance, which allows the panel to be operated with less energy consumption.

[0010] Another recently developed mode is the XB-FFS mode, in which the liquid crystal medium additionally contains a polar liquid crystal compound with a low dielectric anisotropy.

[0011] Liquid crystal compositions suitable for LCDs, especially FFS and IPS displays, are known in the prior art, for example, can be learned from JP07-181 439(A), EP 0 667 555, EP 0 673986, DE 195 09 410, DE 195 28 106 and DE195 28 107. However, these compositions have certain disadvantages. Among other drawbacks, most of them result in an unfavorable long addressing time, have insufficient resistivity values and / or require an excessively high operating voltage. Herein, it is necessary to improve not only the operating performance but also the storage life.

[0012] FFS and IPS displays can be operated as active matrix displays (AMD) or passive matrix displays (PMD). In the case of an active matrix display, usually each pixel is addressed by an integrated, non-linear active element, such as a thin film transistor (TFT), while in the case of a passive matrix display, usually each pixel is addressed by a multiplexing method known in the prior art.

[0013] Preferably, the display according to the invention is addressed by active matrix, preferably by a TFT matrix. However, the liquid crystal medium according to the invention can also be advantageously used in displays with other known addressing methods.

[0014] Typical applications of IPS and FFS technologies are monitors, laptop computers, televisions, mobile phones, tablet PCs, etc. Both IPS and FFS technologies have certain advantages over other LCD technologies, such as, for example, the vertical alignment (VA) technology, for example, the wide viewing angle dependence of the contrast ratio.

[0015] The provision of other liquid crystal media and their use in displays with high transmittance, good black state and high contrast ratio are the core challenges of modern FFS and IPS applications. In addition, modern applications also require good low-temperature stability and fast addressing time.

[0016] So far, it has not been possible to design a suitable liquid crystal medium with high contrast ratio (such as high elastic constant K1 and K av ), low temperature stability and low response time. Therefore, the overall image quality of these devices still needs to be further improved. Especially in the field of gaming applications, in order to achieve fast switching speed, other parameters related to image quality are often sacrificed.

[0017] The object of the present invention is to provide a liquid crystal medium, especially for energy-saving gaming FFS and IPS displays and AR / VR headsets or displays, also for TN, positive VA or STN displays, and especially for active matrix displays, such as those addressed by TFTs, which have a high average elastic constant K av With low response time parameters (γ1 / K1) and low rotational viscosity and relatively low birefringence Δn. In addition, they need to have high resistivity, low threshold voltage, high dielectric anisotropy, good low-temperature stability (LTS), fast response time, and be able to achieve high brightness. For FFS displays, the response time, contrast ratio, brightness and reliability need to be further optimized. However, it has been found that the liquid crystal materials of the prior art often cannot meet all these requirements simultaneously.

[0018] Surprisingly, the above technical problems are solved by providing the liquid crystal medium described and claimed below.

[0019] The prior art, such as WO 2010 / 099853 A1 and DE 10 2010 027 099A1, discloses liquid crystal media containing thiophene. WO 2010 / 099853 A1 teaches compounds containing thiophene-2,5-diyl units directly linked to 2- and / or 6-substituted 1,4-phenylene units. WO 2010 / 099853 A1 describes the development of novel materials for LC displays. This object is achieved by providing compounds of the following general formula containing 2,6-difluoro-1,4-phenylene units adjacent to the thiophene moiety:

[0020]

[0021] wherein A 1 and A 2 among other meanings, also represent 1,4-phenylene or 1,4-cyclohexylene units, Z 1 and Z 2 represent a bridging element or a single bond.

[0022] WO 2009 / 129915 A1 describes compounds of the following general formula containing 2-fluoro-1,4-phenylene units adjacent to the thiophene moiety:

[0023]

[0024] and a nematic liquid crystal medium containing the compound.

[0025] WO 2014 / 053204 describes a mesogenic medium exhibiting a blue phase, which comprises a first component composed of one or more compounds of formula I-M

[0026]

[0027] and a second component composed of one or more compounds of formula I-U

[0028]

[0029] Now it has surprisingly been found that the liquid crystal media containing a combination of compounds of formula I and M according to the invention exhibit several significant improvements, especially when used in FFS mode displays, such as a high average elastic constant K av , a combination of a low response time parameter (γ1 / K1) with a low rotational viscosity and good solubility, and enable a fast response time,

[0030]

[0031] wherein the individual substituents are specified in claim 1.

[0032] In addition, the liquid crystal medium according to the invention has high-definition bright spots, excellent low-temperature stability (LTS) and provides optimal moving picture quality and improved overall image quality, especially high contrast. SUMMARY OF THE INVENTION

[0033] The present invention relates to a liquid crystal medium, characterized in that it comprises one or more compounds of formula I

[0034]

[0035] and one or more compounds of formula M

[0036]

[0037] wherein each substituent has the following meanings:

[0038] denotes

[0039] denotes

[0040] A 0 、A 1 and A 2 each independently of one another denote phenylene-1,4-diyl, wherein furthermore one or two CH groups may be replaced by N, and one or more H atoms may be replaced by halogen, CN, CH3, CHF2, CH2F, CF3, OCH3, OCHF2 or OCF3; cyclohexane-1,4-diyl, wherein furthermore one or two non-adjacent CH2 groups may independently of one another be replaced by O and / or S, and one or more H atoms may be replaced by F; cyclohexene-1,4-diyl; bicyclo[1.1.1]pentane-1,3-diyl; bicyclo[2.2.2]octane-1,4-diyl; spiro[3.3]heptane-2,6-diyl; tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl;

[0041] R 1 、R 2 and R 3 each independently of one another are an H atom, a halogen atom, an alkyl or alkoxy group having 1 - 12 C atoms or an alkenyl or alkenoxy group having 2 - 12 C atoms, wherein one or more non-adjacent CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- substituted in such a way that the O atoms are not directly connected to one another and in which one or more H atoms may be substituted by halogen atoms, or cycloalkyl or cycloalkoxy having 3 to 12 C atoms, in which one or more H atoms may be substituted by halogen atoms;

[0042] Y 0 is an H atom, an alkyl group having 1 to 3 C atoms or an alkenyl group having 2 to 3 C atoms, wherein one or more non-adjacent CH2 groups are optionally substituted by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other;

[0043] W represents =N-, =(CH)- or =(CF)-;

[0044] X 0 represents a halogen atom, CN, SCN, NCS, an alkyl or alkoxy group having 1 to 3 C atoms, or an alkenyl or alkenyloxy group having 2 or 3 C atoms, wherein one or more H atoms are replaced by a halogen atom;

[0045] Z 1 , Z 2 , Z 3 and Z 4 Each independently represents -CF2O-, -OCF2, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2H4-, -C2F4-, -CF2CH2-, -CH2CF2-, -CFHCFH-, -CFHCH2-, -CH2CFH-, -CF2CFH-, -CFHCF2-, -CH=CH-, -CF=CH-, -CH=CF-, -CF=CF-, -C≡C- or a single bond;

[0046] L 1-4 Each independently represents H or F;

[0047] Y 1 and Y 2 each independently of one another represents H or a straight-chain or branched alkyl or alkoxy group having 1 to 6 C atoms, or a cycloalkyl or cycloalkoxy group having 3 to 6 C atoms;

[0048] k and l each independently represent 0, 1, 2 or 3; and

[0049] m and n each independently represent 0, 1 or 2,

[0050] Where (m+n)≥1.

[0051] The liquid crystal medium according to the invention is particularly suitable for gaming AR / VR headsets or displays and energy-saving LC displays and their polymer-stabilized variants based on dielectrically positive liquid crystals in FFS, HB-FFS, XB-FFS, and IPS modes.

[0052] The invention also relates to the use of the liquid crystal medium as described in the context for electro-optical purposes, in particular for LC displays, shutter glasses, LC windows, 3D applications, preferably in TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-HB-FFS, PS-XB-FFS, SA-HB-FFS, SA-XB-FFS, polymer-stabilized SA-HB-FFS, polymer-stabilized SA-XB-FFS, positive VA, and positive PS-VA displays, very preferably in FFS, HB-FFS, IPS, PS-HB-FFS, and PS-IPS displays.

[0053] The invention also relates to an electro-optical LC display comprising the liquid crystal medium as described in the context, in particular a TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-HB-FFS, PS-XB-FFS, SA-HB-FFS, SA-XB-FFS, polymer-stabilized SA-HB-FFS, polymer-stabilized SA-XB-FFS, positive VA, or positive PS-VA display, preferably an FFS, HB-FFS, IPS, PS-HB-FFS, or PS-IPS display.

[0054] In this application, all atoms also include their isotopes. In some embodiments, one or more hydrogen atoms (H) may optionally be replaced by deuterium (D); a high degree of deuteration can enable or simplify the analytical determination of compounds, especially in the case of low concentrations.

[0055] In Formulas I and M, if R 1 、R 2 and R 3 represent an alkyl and / or an alkoxy group, it may be straight-chain or branched. It is preferably straight-chain, has 2, 3, 4, 5, or 6 C atoms and preferably represents ethyl, propyl, butyl, pentyl, hexyl, ethoxy, propoxy, butoxy, pentyloxy, or hexyloxy, as well as methyl, methoxy.

[0056] 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.

[0057] If R 1 、R 2 and R 3 represent an alkoxy or an oxaalkyl group, they may also contain one or more additional oxygen atoms, provided that the oxygen atoms are not directly connected to each other.

[0058] In another preferred embodiment, one or more of R 1 、R 2 and R 3 are selected from the following groups -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 one or more of R 1 、R 2 and R 3 are selected from the following groups -OCH2OCH3, -O(CH2)2OCH3, -O(CH2)3OCH3, -O(CH2)4OCH3, -O(CH2)2F, -O(CH2)3F, -O(CH2)4F.

[0059] If R 1 、R 2 and R 3 represent an alkenyl group, it may be straight-chain or branched-chain. It is preferably straight-chain and has 2 - 10 C atoms. Correspondingly, it represents, in particular, vinyl, prop-1- or -2-enyl, but-1-,-2- or -3-enyl, pent-1-,-2-,-3- or -4-enyl, hex-1-,-2-,-3-,-4- or -5-enyl, hept-1-,-2-,-3-,-4-,-5- or -6-enyl, oct-1-,-2-,-3-,-4-,-5-,-6- or -7-enyl, non-1-,-2-,-3-,-4-,-5-,-6-,-7- or -8-enyl, dec-1-,-2-,-3-,-4-,-5-,-6-,-7-,-8- or -9-enyl.

[0060] If R 1 、R 2 and R 3Represents an alkyl or alkenyl group that is at least monosubstituted by a halogen, which group is preferably straight-chain, and the halogen is preferably F or Cl. In the case of polysubstitution, the halogen is preferably F. The resulting group also includes perfluorinated groups. In the case of monosubstitution, the fluorine or chlorine substituent can be in any desired position, but is preferably in the ω-position.

[0061] A in formula I 0 、A 1 and A 2 Particularly preferably represents 1,4-phenylene-diyl, which can also be monosubstituted or polysubstituted by F, and also represents cyclohexane-1,4-diyl, cyclohexene-1,4-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl.

[0062] A in formula I 0 、A 1 and A 2 Particularly preferably represents

[0063]

[0064] Preferably unsubstituted 1,4-phenylene, where L 1 and L 2 Represents a halogen, CF3 or CN, preferably F.

[0065] Z in formula I 1 and Z 2 as well as Z in formula M 3 and Z 4 Particularly preferably represents -CF2O-, -OCF2- or a single bond, with a single bond being most preferred.

[0066] In addition, the groups R in formulas I and M are preferably 1 、R 2 and R 3 Represents H, a halogen atom or an alkyl, alkenyl, alkynyl or alkoxy group having at most 12, preferably at most 8, C atoms, each of which is optionally substituted by a halogen, especially by F, particularly preferably H, F, an alkyl, alkenyl or alkynyl group having at most 8 C atoms. Preferably, at least one of the groups R 1 、R 2 and R 3 is not H, particularly preferably the groups R 1 、R 2 and R 3 do not represent H atoms. R 1 、R 2 and R 3 Very particularly preferably equals an alkyl group. Very particularly preferably, R 1 and R 3 are alkyl groups. R 1 、R 2and R 3 each independently very particularly preferably denote unbranched alkyl groups having 1 - 5 C atoms. If R 1 , R 2 and R 3 denote substituted alkyl, alkoxy, alkenyl or alkynyl groups, then the total number of C atoms in two of the groups R 1 , R 2 and R 3 are each preferably less than 10 or the total number of C atoms in two of the groups R 1 , R 2 and R 3 is each preferably less than 10.

[0067] Preferred alkyl groups are, for example, methyl, ethyl, n - propyl, n - butyl, n - pentyl, n - hexyl, n - heptyl and n - octyl.

[0068] Preferred alkenyl groups are, for example, vinyl, propenyl, butenyl and pentenyl.

[0069] Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl and octynyl.

[0070] Preferred alkoxy groups are, for example, methoxy, ethoxy, n - propoxy, n - butoxy, n - pentoxy, n - hexoxy, n - heptoxy, n - octoxy.

[0071] Halogen preferably denotes F or Cl, most preferably F.

[0072] Compound of formula I

[0073] Preferably comprises a liquid - crystal medium of compounds of formula I, in which A 0 denotes phenylene - 1,4 - diyl, in which furthermore one or two CH groups may be replaced by N and one or more H atoms may be replaced by halogen, CN, CH3, CHF2, CH2F, OCH3, OCHF2, CF3 or OCF3. Particularly preferred are compounds in which A 0 denotes

[0074]

[0075] More preferably

[0076] And particularly preferably in which

[0077] A 0 denotes

[0078] Preferred compounds of formula I can endow the liquid - crystal medium with a particularly high clearing point, low rotational viscosity, wide nematic range, high birefringence and excellent thermal and UV stability.

[0079] Furthermore, preferred are compounds of formula I, wherein k and l represent 0, 1 or 2, particularly preferably 0 or 1. Particularly preferred are compounds of formula I, wherein l represents 0, i.e. the thiophene ring is the terminal ring. Furthermore, preferred are compounds of formula I, wherein k represents 0, 1 or 2, preferably 1 or 2, very particularly preferably 1.

[0080] A in formula I 0 , A 1 and A 2 Particularly preferably represent 1,4-phenylene-diyl, which may also be mono- or polysubstituted by F, and may furthermore represent cyclohexane-1,4-diyl, 1,4-cyclohexenylene-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl.

[0081] Z in formula I 1 and Z 2 Particularly preferably represent -CF2O-, -OCF2- or a single bond, with a single bond being particularly preferred.

[0082] A in formula I 1 and A 2 Particularly preferably represent

[0083]

[0084] Preferably unsubstituted 1,4-phenylene, wherein L represents halogen, CF3 or CN, preferably F.

[0085] Furthermore, preferred are compounds of formula I, wherein R 1 and R 2 each independently of one another represent H, F, Cl, Br, -CN, -SCN, -NCS, SF5, halogen or an alkyl, alkenyl or alkynyl having at most 8, preferably at most 5 C atoms, each of which is optionally substituted by halogen, in particular by F.

[0086] Particularly preferably, the groups R 1 and R 2 in formula I represent H, halogen or an alkyl, alkenyl, alkynyl or alkoxy having at most 12, preferably at most 8 C atoms, each of which is optionally substituted by halogen, in particular by F, with H, F, an alkyl, alkenyl or alkynyl having at most 8 C atoms being particularly preferred. Preferably, at least one group is not H, particularly preferably the groups R 1 and R 2 are both not H. R 1 Very particularly preferably equals alkyl. R 2 Furthermore, preferably H, alkyl or fluorine. Very particularly preferably, R 1 is alkyl and R 2 is H or alkyl. R1 , R 2 each independently very particularly preferably represents an unbranched alkyl group having 1 to 5 C atoms. If R 1 and R 2 represent a substituted alkyl, alkoxy, alkenyl or alkynyl group, the total number of C atoms in the two groups R 1 and R 2 is preferably less than 10.

[0087] Preferred alkyl groups are, for example, methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl and n-octyl.

[0088] Preferred alkenyl groups are, for example, vinyl, propenyl, butenyl and pentenyl.

[0089] Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl and octynyl.

[0090] Preferred alkoxy groups are, for example, methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy.

[0091] Halogen preferably represents F or Cl, most preferably F.

[0092] Particularly preferred compounds of formula I are compounds selected from the following sub-formulas:

[0093]

[0094] wherein Y 0 , R 1 and R 2 have the meanings shown in formula I, and L 1 to L 6 independently represent H or F. Y 0 represents an H atom, an alkyl group having 1 to 3 C atoms or an alkenyl group having 2 to 3 C atoms, wherein one or more non-adjacent CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other;

[0095] R 1 and R 2 preferably represent an optionally fluorinated alkyl or alkoxy group having 1 to 12 C atoms, an optionally fluorinated alkenyl or alkynyl group having 2 to 12 C atoms, an optionally fluorinated cycloalkyl group having 3 to 12 C atoms. Y 0 and Y 3 are preferably an H atom or a methyl group.

[0096] Particularly preferably, an optionally fluorinated alkyl, alkenyl or alkynyl group having at most 5 C atoms. L in Formulas I-1-1 to I-1-6 2 preferably represents F. In Formulas I-1-4 to I-1-6, L 3 and L 4 preferably represent H. In Formulas I-1-4 to I-1-6, L 3 and L 4 preferably represent F.

[0097] In a particularly preferred embodiment, the compound of Formula I is selected from the following structures:

[0098]

[0099] wherein R 1 has the same meaning as in General Formula I;

[0100] R 2 represents a straight-chain or branched-chain alkyl or alkoxy group having 1-7 C atoms, or an alkenyl, alkenyloxy, alkoxyalkyl group having 2-7 C atoms, or a cycloalkyl or cycloalkyloxy group having 3-12 C atoms, wherein one or more non-adjacent CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen atoms; and

[0101] Y 0 and Y 3 each independently of one another represent an H atom or a straight-chain or branched-chain alkyl group having 1-3 C atoms.

[0102] A liquid crystal medium according to the invention having a particularly high LTS, a wide nematic range and high long-term stability against UV radiation and high temperatures as well as low rotational viscosity can be obtained by means of compounds of the following General Formula I:

[0103]

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110] where Y 0 and Y 3 and R 1 and R 2 are as defined above.

[0111] Furthermore, a liquid crystal medium comprising a compound of the following formula I is particularly preferred:

[0112]

[0113]

[0114]

[0115]

[0116] where n and m each independently of one another represent 0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 11 or 12.

[0117] The most preferred compounds of formula I include, in particular, one or more of the following:

[0118]

[0119]

[0120]

[0121] As a further possibility, the following compounds of formula I can be used:

[0122]

[0123]

[0124]

[0125] As a further possibility, the following compounds of formula I can be used:

[0126]

[0127]

[0128]

[0129]

[0130] The compounds of formula I can be prepared in a manner analogous to methods known to those skilled in the art and described in standard works of organic chemistry, such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Thieme-Verlag, Stuttgart.

[0131] The compounds of formula M

[0132] Preferably, one or more compounds of formula M are selected from the compounds of the following formulae:

[0133]

[0134]

[0135]

[0136]

[0137] wherein

[0138] R 3 represents an alkyl or alkoxy group having 1 - 6 C atoms or an alkenyl group having 2 - 6 C atoms, wherein one or more CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen atoms

[0139] L 1-4 each independently of one another represents H or F;

[0140] Y 1 and Y 2 each independently of one another represents an H atom or a methyl group, preferably an H atom; and

[0141] X 0 represents CN, SCN, NCS or an alkyl group having 1 - 6 C atoms, wherein one or more H atoms are replaced by halogen atoms.

[0142] In a more preferred embodiment of the invention, one or more compounds of formula M are selected from the compounds of the following formulae:

[0143]

[0144]

[0145]

[0146]

[0147]

[0148] wherein

[0149] R 3 represents an alkyl or alkoxy group having 1 - 6 C atoms or an alkenyl group having 2 - 6 C atoms, wherein one or more CH₂ groups are optionally replaced by -C≡C-, -CF₂O-, -OCF₂-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen atoms, and

[0150] X 0 represents CN, SCN, NCS or an alkyl group having 1 - 6 C atoms, wherein one or more H atoms are replaced by halogen atoms.

[0151] The most preferred compounds of formula M include, in particular, one or more of the following:

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158]

[0159]

[0160]

[0161] The proportion of the compound of formula M in the liquid crystal medium is preferably 0.5 - 15% by weight, very preferably 1 - 10% by weight, and most preferably 2 - 8% by weight.

[0162] Other components

[0163] Advantageously, the liquid crystal medium of the present invention comprises one or more compounds of formula LP1 and LP2

[0164]

[0165] Each of the substituents has the following meanings:

[0166] R 0 has one of the meanings given for R in formula I; 1 one of;

[0167] R 2 represents an alkyl or alkoxy group having 1 - 12 C atoms or an alkenyl or alkenyloxy group having 2 - 12 C atoms, where one or more non-adjacent CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, and where one or more H atoms may be replaced by a cycloalkyl or cycloalkoxy group having 3 - 12 C atoms;

[0168] L 1 and L 2 each independently of one another represent H, F or Cl;

[0169] Y 0 represents H or CH3;

[0170] X 0 represents an F atom, CN, SCN, NCS or an alkyl or alkoxy group having 1 - 6 C atoms or an alkenyl or alkenyloxy group having 2 - 6 C atoms, where one or more H atoms are replaced by F atoms; and

[0171] m and n each independently of one another represent 0 or 1.

[0172] One or more compounds of formulae LP1 and LP2 can preferably be described by the following formulae LP1 - 1 to LP2 - 6:

[0173]

[0174]

[0175] where

[0176] R 0 is an alkyl or alkoxy group having 1 - 6 C atoms or an alkenyl group having 2 - 6 C atoms, where one or more CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, and where one or more H atoms may be replaced by a halogen atom;

[0177] R 2is an alkyl group having 1 to 6 carbon atoms, wherein one or more CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, and one or more H atoms may be replaced by halogen atoms;

[0178] X 0 is an F atom or an alkyl or alkoxy group having 1 to 3 carbon atoms or an alkenyl or alkenyloxy group having 2 or 3 carbon atoms, wherein one or more H atoms are replaced by F atoms, and

[0179] Y 0 is H or CH3.

[0180] The compounds of general formulas LP1 and LP2 can also be represented by one of the following:

[0181]

[0182]

[0183] wherein

[0184] R 0 is an alkyl or alkoxy group having 1 to 12 carbon atoms, wherein one or more CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, and one or more H atoms may be replaced by halogen atoms, preferably an alkyl group having 1 to 4 carbon atoms, an alkenyl or alkenyloxy group having 2 to 6 carbon atoms or a cycloalkyl or cycloalkoxy group having 3 to 6 carbon atoms, wherein vinyl, allyl or cyclopentyl is particularly preferred;

[0185] n represents 1, 2, 3, 4 or 5; and

[0186] m represents 1, 2, 3 or 4.

[0187] Particularly preferred compounds of formula LP1 are compounds selected from the following sub-formulas:

[0188]

[0189]

[0190]

[0191] wherein Y 0 is H or CH3, preferably H.

[0192] Very preferably, the compounds of formulae LP1-1a, LP1-1b and LP1-1c, and most preferably the compound of formula LP1-1a.

[0193] Particularly preferred compounds of formula LP2 are compounds selected from the following sub-formulae:

[0194]

[0195]

[0196]

[0197] wherein Y 0 is H or CH3, preferably H.

[0198] Very preferably, the compounds of formulae LP2-1a, LP2-1b, LP2-1c, LP2-1d and LP2-1i, LP2-2b, LP2-3a, LP2-3c, and most preferably the compound of formula LP2-1b.

[0199] The total proportion of the compounds of formula LP1 or LP2 or their sub-formulae in the liquid crystal medium is preferably 2-35% by weight, very preferably 3-30% by weight, and most preferably 4-20% by weight.

[0200] Preferably, the liquid crystal medium contains 1, 2 or 3 compounds of formula LP1 or LP2 or their sub-formulae. In a particularly preferred embodiment, the liquid crystal medium contains at least one compound of formula LP1 and at least one compound of formula LP2.

[0201] In a preferred embodiment, the liquid crystal medium may further contain one or more compounds selected from the following formulae II and III:

[0202]

[0203] wherein each substituent independently of one another and in each occurrence is the same or different and has the following meanings:

[0204]

[0205]

[0206] R 0 has one of the meanings given for R in formula I 1 given,

[0207] X 0 are independently of one another F, Cl, an alkyl, alkenyl, alkoxy or alkenyloxy having at most 6 C atoms, where one or more H atoms are replaced by halogen atoms,

[0208] L 1-6 are each independently H or F, and

[0209] Y 0 is H or CH3.

[0210] Preferred compounds of formulae II and III are those in which Y 0 is H.

[0211] Further preferred compounds of formulae II and III are those in which R 0 represents an alkyl group having 1 - 6 C atoms, very preferably ethyl or propyl, and X 0 represents F or OCF3, very preferably F.

[0212] In a preferred embodiment, the liquid crystal medium comprises one or more compounds of formula II selected from the following sub-formulae:

[0213]

[0214]

[0215] wherein R 0 and X 0 have the meanings given in formula II.

[0216] Preferred compounds are those of formulae II-1, II-2 and II-3, very preferably those of formulae II-1 and II-2.

[0217] In compounds of formulae II-1 to II-7, R 0 preferably represents an alkyl group having 1 - 6 C atoms, very preferably ethyl or propyl, and X 0 preferably represents F or OCF3, very preferably F.

[0218] In one embodiment, the liquid crystal medium comprises one or more compounds of formula II or its sub-formulae as described in the context, wherein Y 0 is CH3. Very preferably, the liquid crystal medium according to this preferred embodiment comprises one or more compounds of formula II selected from the following sub-formulae:

[0219]

[0220]

[0221] wherein R 0 and X 0 have the meanings given in formula II.

[0222] Preferred compounds are those of formulae IIA-1, IIA-2 and IIA-3, very preferably those of formulae IIA-1 and IIA-2.

[0223] Among the compounds of formulae IIA-1 to IIA-7, R 0 preferably represents an alkyl group having 1 to 6 C atoms, very preferably ethyl or propyl, and X 0 preferably represents F or OCF3, very preferably F.

[0224] The proportion of the compounds of formula II in the liquid crystal medium is generally 0 - 20% by weight, very preferably 1 - 15% by weight, and most preferably 2 - 10% by weight.

[0225] In a further preferred embodiment, the liquid crystal medium comprises one or more compounds of formula III selected from the following sub-formulae:

[0226]

[0227]

[0228]

[0229]

[0230]

[0231] wherein R 0 and X 0 have the meanings given in formula II.

[0232] Preferred compounds are those of formulae III-1, III-4, III-6, III-16, III-19 and III-20.

[0233] Among the compounds of formulae III-1 to III-21, R 0 preferably represents an alkyl group having 1 to 6 C atoms, very preferably ethyl or propyl, and X 0 preferably represents F or OCF3, very preferably F, and Y 0 preferably represents H.

[0234] The liquid crystal medium may contain one or more compounds of formula III or its sub-formulae as described in the context, wherein Y 0 is CH3. Very preferably, the medium according to this preferred embodiment comprises one or more compounds of formula III selected from the following sub-formulae:

[0235]

[0236]

[0237]

[0238]

[0239] wherein R 0 and X 0 have the meanings given in formula III.

[0240] Preferred compounds are those of formulae IIIA-1, IIIA-4, IIIA-6, IIIA-16, IIIA-19 and IIIA-20.

[0241] Among the compounds of formulae IIIA-1 to IIIA-21, R 0 preferably represents an alkyl group having 1 to 6 C atoms, very preferably ethyl or propyl, X 0 preferably represents F or OCF3, very preferably F, and Y 2 preferably represents F.

[0242] The proportion of the compounds of formula III in the liquid crystal medium is preferably 5 to 60% by weight, very preferably 10 to 50% by weight, and most preferably 20 to 40% by weight.

[0243] In a further preferred embodiment, the liquid crystal medium may further comprise one or more compounds selected from the following formulae:

[0244]

[0245]

[0246] wherein

[0247] R 0 、X 0 、L 1-4 and Y 0 have the meanings indicated in formulae II and III;

[0248] Z 0 represents -C2H4-, -(CH2)4-, -CH=CH-, -CF=CF-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH2O-, -OCH2-, -COO-, -CF2O- or -OCF2-, and is also a single bond in formulae V and VI; and

[0249] s represents 0 or 1.

[0250] The compounds of formula IV are preferably selected from the following formulae:

[0251]

[0252] wherein R 0and X 0 have the meanings shown in Formulas II and III.

[0253] R 0 preferably represents an alkyl group having 1 to 6 C atoms. X 0 preferably represents F or OCF3, and also represents OCF═CF2 or Cl.

[0254] The compounds of Formula IVa are preferably represented by the following sub-formulas:

[0255]

[0256] The compounds of Formula IVb are preferably represented by the following formula:

[0257]

[0258] The compounds of Formula IVc are preferably represented by the following sub-formulas:

[0259]

[0260] wherein R 0 has the meaning shown in Formula II and is preferably propyl or pentyl.

[0261] The compounds of Formula IVc, in particular the compounds of Formula IVc-1, are preferably used in the liquid crystal medium according to the invention in an amount of 1 to 20% by weight, particularly preferably 2 to 15% by weight.

[0262] The compounds of Formula V are preferably selected from the following sub-formulas:

[0263]

[0264]

[0265] wherein R 0 and X 0 have the meanings shown in Formula II.

[0266] R 0 preferably represents an alkyl group having 1 to 6 C atoms. X 0 preferably represents F or OCF3, and also represents OCHF2, CF3, OCF═CF2 and OCH═CF2.

[0267] The compounds of Formula VI are preferably selected from the following sub-formulas:

[0268]

[0269]

[0270] wherein R 0 and X 0has the meaning shown in formula II.

[0271] R 0 preferably represents an alkyl group having 1 - 6 C atoms. X 0 preferably represents F, and also represents OCF3, CF3, CF = CF2, OCHF2 and OCH = CF2;

[0272] The compounds of formula VII are preferably selected from the following sub - formulas:

[0273]

[0274]

[0275] wherein R 0 and X 0 have the meaning shown in formula II.

[0276] The compounds of formula VIII can be represented by the following sub - formulas:

[0277]

[0278] wherein R 0 and X 0 have the meaning shown in formula II.

[0279] R 0 preferably represents an alkyl group having 1 - 6 C atoms. X 0 preferably represents F, and also represents OCF3, OCHF2 and OCH = CF2.

[0280] In some embodiments, the liquid crystal medium further comprises one or more compounds selected from the following formulas:

[0281]

[0282]

[0283] wherein

[0284] R 0 and X 0 each independently of one another have one of the meanings shown in formula II,

[0285] L 1-4 each independently of one another represents H or F,

[0286] Y 0 represents H or CH3, preferably H,

[0287] X 0 is preferably F, Cl, CF3, OCF3 or OCHF2,

[0288] R0 Preferably represents an alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl group, each having up to 6 C atoms.

[0289] Very preferably, the liquid crystal medium according to the invention comprises one or more compounds of formula XXa:

[0290]

[0291] wherein R 0 has the meaning shown in LP1. R 0 Preferably represents a straight-chain alkyl or alkenyl group, especially ethyl, n-propyl, n-butyl or n-pentyl, and very particularly preferably n-propyl.

[0292] Compounds of formula XX, especially compounds of formula XXa, are preferably used in the liquid crystal medium according to the invention in an amount of 0 - 15% by weight, particularly preferably 1 - 10% by weight.

[0293] Very preferably, the liquid crystal medium according to the invention comprises one or more compounds of formula XXIa:

[0294]

[0295] wherein R 0 has the meaning shown in LP1. R 0 Preferably represents a straight-chain alkyl group, especially ethyl, n-propyl, n-butyl or n-pentyl, and very particularly preferably n-propyl.

[0296] Compounds of formula XXI, especially compounds of formula XXIa, are preferably used in the liquid crystal medium according to the invention in an amount of 1 - 15% by weight, particularly preferably 2 - 10% by weight.

[0297] Further preferably, the liquid crystal medium according to the invention comprises one or more compounds of formula XXIIIa:

[0298]

[0299] wherein R 0 has the meaning shown in LP1. R 0 Preferably represents a straight-chain alkyl group, especially ethyl, n-propyl, n-butyl or n-pentyl, and very particularly preferably n-propyl or a cycloalkyl group, especially cyclopentyl.

[0300] Preferred specific compounds of XXIIIa include, in particular

[0301]

[0302] Compounds of formula XXIII, in particular compounds of formula XXIIIa, are preferably used in the liquid crystal medium according to the invention in an amount of 0.5 to 5% by weight, particularly preferably 0.5 to 2% by weight.

[0303] The liquid crystal medium may also contain one or more compounds of formula XXIV:

[0304]

[0305] wherein R 0 、X 0 and L 1-6 have the meanings shown in formula III, s represents 0 or 1, and

[0306] represents

[0307] In formula XXIV, X 0 may also represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. The alkyl or alkoxy group is preferably straight-chain.

[0308] R 0 preferably represents an alkyl group having 1 to 6 carbon atoms. X 0 preferably represents F;

[0309] Compounds of formula XXIV are preferably selected from the following sub-formulas:

[0310]

[0311]

[0312]

[0313] wherein R 0 、X 0 and L 1 have the meanings shown in formula III. R 0 preferably represents an alkyl group having 1 to 6 carbon atoms. X 0 preferably represents F, and L 1 is preferably F;

[0314] is preferably

[0315]

[0316] R 0 is a straight-chain alkyl or alkenyl group having 2 to 6 carbon atoms;

[0317] The liquid crystal medium may also contain one or more of the following compounds of the following formula:

[0318]

[0319] wherein R 1 and X 0 each have the meanings shown for R 0 and X 0 in formula II. R 1 preferably represents an alkyl group having 1 - 6 C atoms. X 0 preferably represents F or Cl.

[0320] The liquid crystal medium may also optionally contain one or more compounds of the following formula:

[0321]

[0322] wherein R 1 and X 0 each have the meanings of R 0 and X 0 shown in formula II. R 1 preferably represents an alkyl group having 1 - 6 C atoms. X 0 preferably represents F. The liquid crystal medium according to the invention very particularly preferably contains one or more compounds of formula XXIX, wherein X 0 preferably represents F.

[0323] The compounds of formulas XXVI - XXIX are preferably used in the liquid crystal medium according to the invention in an amount of 1 - 20% by weight, particularly preferably 1 - 15% by weight. A particularly preferred liquid crystal medium contains at least one compound of formula XXIX and / or XXX.

[0324] Very preferably, the liquid crystal medium according to the invention contains one or more compounds of formula XXIXa:

[0325]

[0326] wherein R 1 has the meaning shown in formula II and preferably represents a straight-chain alkyl group, in particular ethyl, n-propyl, n-butyl or n-pentyl, and very particularly preferably n-propyl.

[0327] The compounds of formulas XXIX and XXX are preferably used in the liquid crystal medium of the present invention in an amount of 1 - 15% by weight, particularly preferably 2 - 10% by weight.

[0328] Preferably, in addition to the compounds of formula I and M and optionally LP1 and / or LP2, II and / or III, the liquid crystal medium further contains one or more compounds selected from the following formulas:

[0329]

[0330]

[0331] wherein

[0332] “alkyl” and “alkyl * ” each independently represent an alkyl group having 1 to 6 C atoms;

[0333] “alkenyl” and “alkenyl * ” each independently represent an alkenyl group having 2 to 6 C atoms.

[0334] Compounds of the formulas Z1 and Z2 are highly preferred.

[0335] Preferred compounds of the formulas Z1 to Z10 are those selected from the following sub-formulas:

[0336]

[0337]

[0338]

[0339] In another preferred embodiment, the liquid crystal medium contains one or more compounds of the formula Z1 or its preferred sub-formulas and / or one or more compounds selected from the formulas Z2, Z3, Z4, and Z5 or their preferred sub-formulas.

[0340] Preferably, in the liquid crystal medium, the total proportion of the compounds of the formulas Z1, Z2, Z3, Z4, Z5, and Z6 or their sub-formulas (e.g., CC-3-V) is 10 to 65% by weight, very preferably 20 to 60% by weight, and most preferably 25 to 55% by weight. In a more preferred embodiment, based on the total weight of the liquid crystal medium, the concentration range of the compound of the formula Z1-1 is 10 to 60% by weight, more preferably 25 to 50% by weight. In a further preferred embodiment, the liquid crystal medium in total contains 50 to 70% by weight of the compounds represented by the formulas Z1-1 and Z4-2.

[0341] Preferably, the medium contains 1, 2, or 3 compounds selected from the formulas Z1, Z2, Z3, and Z4 or their sub-formulas.

[0342] The liquid crystal medium may further contain one or more compounds of the following general formulas:

[0343]

[0344] wherein

[0345] R 1 and R 2 each independently represent C 1-6 alkyl, C 1-6 alkoxy, or C2-6 Alkenyl.

[0346] The compounds of formula XII are preferably selected from the following sub-formulas:

[0347]

[0348] wherein "alkyl" and "alkyl * " each independently represent methyl, ethyl, propyl, butyl, pentyl or hexyl.

[0349] Compounds of formula XIIa and XIIc are particularly preferred. In formula XIIb, "alkyl" preferably independently represents n-C3H7, n-C4H9 or n-C5H 11 , especially n-C3H7. In formula XIIc, "alkyl" preferably represents n-C3H7, and "alkyl * " is preferably CH3 or n-C3H7.

[0350] Particularly preferred compounds of formula XII are described by the following structures:

[0351]

[0352] The liquid crystal medium may also contain one or more compounds selected from the following formulas:

[0353]

[0354] wherein L 1 and L 2 have the meanings shown in formula III, and R 1 and R 2 each independently represent an n-alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl having at most 6 C atoms, and preferably each independently represent an alkyl having 1-6 C atoms; in the compounds of formula XIV, the substituents R 1 and R 2 at least one of which preferably represents an alkenyl having 2-6 C atoms.

[0355] The liquid crystal medium may also optionally contain one or more compounds of formula XIV, wherein at least one of the substituents R 1 and R 2 represents an alkenyl having 2 to 6 C atoms, preferably those selected from the following sub-formulas:

[0356]

[0357]

[0358] wherein "alkyl" and "alkyl* ” has the above meanings and each preferably independently represents methyl, ethyl or propyl.

[0359] The compounds of formula XIV are preferably selected from the following sub-formulas:

[0360]

[0361]

[0362] Very preferably, the compounds of formula XIVd-1, XIVe-1, XIVe-2 and XIVe-3.

[0363] The liquid crystal medium may also optionally contain one or more compounds of formula XV, wherein the substituents R 1 and R 2 at least one of which represents an alkyl or alkoxy group having 2-6 C atoms and is preferably selected from those of the following sub-formulas:

[0364]

[0365] wherein "alkyl" and "alkyl * " has the above meanings and each preferably independently represents methyl, ethyl or propyl.

[0366] In yet another embodiment, the liquid crystal medium contains one or more compounds of formula XVI:

[0367]

[0368] wherein R 1 and R 2 have the meanings shown in formula I and each preferably independently represents an alkyl group having 1-6 C atoms. L represents H or F.

[0369] Particularly preferred compounds of formula XVI are those of the following sub-formulas:

[0370]

[0371]

[0372] wherein

[0373] "alkyl" and "alkyl * " each independently represent a straight-chain alkyl group having 1-6 C atoms, especially ethyl, propyl or pentyl, and

[0374] "alkenyl" and "alkenyl *”Each independently represents a straight-chain alkenyl group having 2 to 6 carbon atoms, especially CH2=CHC2H4, CH3CH=CHC2H4, CH2=CH, and CH3CH=CH.

[0375] Compounds of formula XVIb and XVIc are particularly preferred. Compounds of the following sub-formulas are very particularly preferred:

[0376]

[0377]

[0378] Compound of formula XVIc-2 is very preferred.

[0379] The liquid crystal medium may optionally contain one or more compounds of the following formula:

[0380]

[0381]

[0382] where

[0383] R 1 and R 2 have the meanings shown in formula I respectively, and preferably each independently represents an alkyl group having 1 to 6 carbon atoms. L represents H or F.

[0384] Compound of formula XVIIa where L is H is very preferred. Compound of formula XVIIb where L is F is very preferred.

[0385] The liquid crystal medium may also contain one or more compounds of the following formula:

[0386]

[0387] where L, R 1 and R 2 have the meanings shown by L in formula M 1 and the meanings shown by R 1 and R 2 in formula I respectively. R 1 and R 2 preferably represent an alkyl group, an alkoxy group, an oxaalkyl group, a fluoroalkyl group or an alkenyl group, each having at most 6 carbon atoms.

[0388] Particularly preferred compounds of formula XXXII are those of the following sub-formulas:

[0389]

[0390]

[0391] wherein

[0392] “alkyl” and “alkyl * ” each independently represent a straight-chain alkyl group having 1 to 6 C atoms, especially ethyl, propyl or pentyl, and

[0393] “alkenyl” represents a straight-chain alkenyl group having 2 to 6 C atoms, especially CH2=CHC2H4, CH3CH=CHC2H4, CH2=CH and CH3CH=CH.

[0394] Compounds of the following sub-formulae are very particularly preferred:

[0395]

[0396] In some other embodiments, the liquid crystal medium comprises one or more compounds of the following formula:

[0397]

[0398] wherein R 1 and R 2 each have the meanings shown in formula I and preferably each independently represent an alkyl group having 1 to 6 C atoms.

[0399] Compound of formula ST

[0400] In some preferred embodiments of the present invention, the liquid crystal medium may further comprise one or more compounds of general formula ST:

[0401]

[0402] wherein each substituent has the following meanings:

[0403] represents

[0404] X 21 、X 22 each independently represent -O-, -CH2-, -CHR 23 -, or -N-R 23 -,

[0405] R 21 and R 22 each independently represent an H atom or an alkyl or alkoxy group having 1 to 12 C atoms, an alkenyl group having 2 to 12 C atoms, an alkynyl group, an alkenyloxy group or an alkoxyalkyl group or a cycloalkyl group having 3 to 12 C atoms, wherein one or more non-adjacent CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- are substituted in such a way that the O atoms are not directly connected to each other, and one or more H atoms may be substituted by a halogen atom or a cycloalkyl or cycloalkyloxy group having 3 to 12 C atoms, and one or more H atoms may be substituted by a halogen atom,

[0406] R 23 represents an H atom, an alkyl or alkoxy group having 1 to 10 C atoms,

[0407] r represents 0 or 1.

[0408] Liquid crystal media containing compounds of the following sub-formulae ST-1, ST-2 and ST-3 exhibit particularly high long-term thermal and UV stability:

[0409]

[0410] wherein each substituent has the following meaning:

[0411] represents

[0412] R 21 and R 22 each independently of one another represent an H atom or an alkyl or alkoxy group having 1 to 7 C atoms, and

[0413] r represents 0 or 1.

[0414] In a particularly preferred embodiment, the compounds of the general formula ST can be selected from the following specific structures:

[0415]

[0416]

[0417]

[0418]

[0419] In other preferred embodiments, the liquid crystal medium according to the invention may comprise at least one other sterically hindered phenol mentioned in Table B below.

[0420] Compound of formula H

[0421] The liquid crystal medium may optionally comprise one or more compounds of formula H

[0422]

[0423] wherein

[0424] R 11each independently represents an H atom, F, an alkyl group having 1 to 20 C atoms, wherein one —CH2— group or, if present, a plurality of —CH2— groups may be replaced by —O— or —C(═O)—, provided that two adjacent —CH2— groups cannot be replaced by —O—, and one or, if present, a plurality of —CH2— groups may be replaced by —CH═CH— or —C≡C—, and wherein one H atom or a plurality of H atoms may be replaced by F, OR 13 , N(R 13 )(R 14 ) or R 15 substitution,

[0425] R 12 each independently represents an H atom, an alkyl group having 1 to 20 C atoms, wherein one —CH2— group or a plurality of —CH2— groups may be replaced by —O— or —C(═O)—, provided that two adjacent —CH2— groups cannot be replaced by —O—, a hydrocarbon group containing a cycloalkyl or alkylcycloalkyl unit, and wherein one —CH2— group or a plurality of —CH2— groups may be replaced by —O— or —C(═O)—, provided that two adjacent —CH2— groups cannot be replaced by —O—, and wherein one H atom or a plurality of H atoms may be replaced by F, OR 13 , N(R 13 )(R 14 ) or R 15 substitution, or an aromatic or heteroaromatic hydrocarbon group, wherein one H atom or a plurality of H atoms may be replaced by OR 13 , N(R 13 )(R 14 ) or R 15 substitution,

[0426] R 13 and R 14 each independently represents an alkyl or acyl group having 1 to 10 C atoms, or an aromatic hydrocarbon or carboxylic acid group having 6 to 12 C atoms,

[0427] R 15 each independently represents an alkyl group having 1 to 10 C atoms, wherein one —CH2— group or a plurality of —CH2— groups may be replaced by —O— or —C(═O)—, provided that two adjacent —CH2— groups cannot be replaced by —O—,

[0428] R 16 each independently represents an H atom, an alkyl or alkoxy group having 1 to 10 C atoms, an O-cycloalkyl having 3 to 12 C atoms, O· or OH,

[0429] S 11 and S 12Each independently represents an alkylene group having 1 to 20 carbon atoms, wherein one -CH2- group or, if present, a plurality of -CH2- groups may be replaced by -O- or -C(=O)-, provided that two adjacent -CH2- groups cannot be replaced by -O-, and wherein one hydrogen atom or a plurality of hydrogen atoms may be replaced by F, OR 13 , N(R 13 )(R 14 ) or R 15 substitution, or represents a single bond,

[0430] Y 11 to Y 14 Each independently represents methyl or ethyl,

[0431] X 11 represents C,

[0432] Z 11 to Z 14 Each independently represents -O-,-(C=O)-,-O-(C=O)-,-(C=O)-O-,-O-(C=O)-O-,-(N-R 13 )-,-N-R 13 -(C=O)- or a single bond; if S 11 is a single bond, then Z 11 and Z 12 do not both represent -O-; if S 12 is a single bond, then Z 13 and Z 14 do not both represent -O-; and if q represents 0, then Z 12 and Z 13 do not both represent -O-,

[0433] p represents 1 or 2,

[0434] q represents 0 or 1,

[0435] o represents (3 - p),

[0436] n represents an integer from 1 to 10,

[0437] m represents an integer from 0 to 8, wherein

[0438] n * p represents an integer from 1 to 10, preferably from 3 to 8, and

[0439] represents an organic moiety having (m + n) bonding sites

[0440] In some preferred embodiments of the present invention, in the compounds of formula H,

[0441] means

[0442]

[0443] (biphenyl-1,1′,3,3′-tetrayl) or

[0444] (benzene-1,2,4,5-tetrayl)

[0445] means

[0446] (benzene-1,3,5-tritrayl) or

[0447] (benzene-1,2,4-tritrayl),

[0448] means -(CH2-)2, -(CH2-)3, -(CH2-)4, -(CH2-)5, -(CH2-)6, -(CH2-)7, -(CH2-)8, i.e. ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl,

[0449] (1,4-phenylene).

[0450] (1,3-phenylene),

[0451] (1,2-phenylene) or

[0452] (trans-1,4-cyclohexylene) and / or

[0453] wherein

[0454] -Z 12 -S 11 -Z 11 - each occurrence independently represents -O-, S 11 -O-,-O-S 11 -O-,-(C=O)-O-S 11 -O-, -O-(C=O)-S 11 -O-,-O-(C=O)-S 11 -(C=O)-O-,-O-S 11 -(C=O)-O-,-(C=O)-O-S 11 -C,-(C=O)-O-S 11-O-(C=O)- or -(N-R 13 )-S 11 -O-,-(N-R 13 -C(=O)-S 11 -(C=O)-O or a single bond, preferably -O-,-S 11 -O-,-O-S 11 -O-,-(C=O)-O-S 11 -O,-O-(C=O)-S 11 -O- or -O-S 11 -(C=O)-O-, and / or

[0455] S 11 preferably represents an alkylene group having 1 to 20 C atoms, and / or

[0456] R 11 if present, represents alkyl, alkoxy or H, preferably H or alkyl, and / or

[0457] R 12 represents H, methyl, ethyl, propyl, isopropyl or 3-heptyl, or cyclohexyl.

[0458] In a preferred embodiment of the present application, in the compound of formula H,

[0459]

[0460] represents a group selected from the following formula

[0461]

[0462] In a further preferred embodiment of the present application, in the compound of formula H,

[0463]

[0464] represents a group selected from the following formula

[0465]

[0466]

[0467] In yet another further preferred embodiment of the invention, in the compound of formula H, where p preferably represents 1,

[0468]

[0469] represents preferably -O-S 11 -O-,-S 11 -O- or -O-S 11 -, particularly preferably -O-S11 -O- or -S 11 -O-.

[0470] In a further preferred embodiment of the present invention, in the compound of formula H, the group

[0471]

[0472] represents a group selected from the following formulas

[0473]

[0474]

[0475] In a further preferred embodiment of the present invention, where p is 2, which may be the same as or different from those described above, in the compound of formula H,

[0476]

[0477] represents a group selected from the following formulas

[0478]

[0479]

[0480] In yet another further preferred embodiment of the present invention, which may be the same as or different from those described above, in the compound of formula H, the group

[0481]

[0482] each independently represents, each time it appears

[0483]

[0484]

[0485] Preferably

[0486]

[0487] The following compounds of general formulas H-1-1, H-1-2 and H-1-3 show to be particularly effective UV stabilizers in the LC mixture, especially with respect to VHR stability:

[0488]

[0489] wherein ZG, R 16 and n are as defined above, and n represents an integer from 1 to 8. These compounds are very suitable for use as stabilizers in the LC mixture and stabilize the VHR of the mixture upon UV exposure.

[0490] In a particularly preferred embodiment, one or more compounds of formula H may be selected from compounds of formulae H-2-1 to H-2-6:

[0491]

[0492]

[0493] wherein

[0494] R 11 each independently of the others represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, in which one —CH₂— group or, if present, more than one —CH₂— group may be replaced by —O— or —C(═O)—, provided that two adjacent —CH₂— groups may not be replaced by —O—, and in which one hydrogen atom or more than one hydrogen atom may be replaced by F, OR 13 , N(R 13 )(R 14 ) or R 15 substitution,

[0495] R 16 represents a hydrogen atom or O·,

[0496] n represents an integer from 0 to 12, and

[0497] S 11 and S 12 each independently of the others represents an alkylene group having 1 to 20 carbon atoms, in which one —CH₂— group or, if present, more than one —CH₂— group may be replaced by —O— or —C(═O)—, provided that two adjacent —CH₂— groups may not be replaced by —O—, and in which one hydrogen atom or more than one hydrogen atom may be replaced by F, OR 13 , N(R 13 )(R 14 ) or R 15 substitution, or represents a single bond.

[0498] In a preferred embodiment of the invention, the liquid crystal medium according to the invention in each case comprises one or more compounds of formula H selected from the compounds of the following formulae:

[0499]

[0500]

[0501]

[0502]

[0503]

[0504]

[0505]

[0506]

[0507] The preferred content of one or more compounds of formula H in the liquid crystal medium depends in particular on the inherent chemical stability of the liquid crystal medium and the nature of the compound of formula H. R 16 Compounds of formula H representing O·, i.e., so-called NO radical type HALS, are preferably used in a proportion of 50 ppm - 1000 ppm based on the weight of the liquid crystal medium. R 16 Compounds of formula H representing H atoms, i.e., so-called NH radical type HALS, are advantageously used in a proportion of 50 ppm - 2000 ppm based on the weight of the liquid crystal medium.

[0508] Further preferred liquid crystal media are selected from the following preferred embodiments, including any combination thereof:

[0509] · Combinations of compounds of formula I and M with compounds of formula LP1, Z1 to Z11 and II and / or III

[0510] · Combinations of compounds of formula I and M with compounds of formula LP2, Z1 to Z11 and II and / or III

[0511] · Combinations of compounds of formula I and M with compounds of formula LP1, LP2, II and / or III and compounds of formula Z1 and Z4

[0512] - The liquid crystal medium contains one or more compounds of formula I and M or their sub-formulas, and LP1 and / or LP2, II and / or III compounds, and one or more compounds selected from the group consisting of formulas Z1, Z2, Z3, Z4, Z5, V, VI, VII, VIII, XIV, XV, XVI, XVIIa, XVIIb, XVIIc, XVIII, XIX, XX, XXI, XXIII, XXIV, XXV, XXVI, XXVII, XXVIII, XXIX, XXX, XXXII, XXXIII and S and their sub-formulas.

[0513] - The liquid crystal medium contains one or more compounds of formula I and M or their sub-formulas, and LP1 and / or LP2, II and / or III compounds, and one or more compounds selected from the group consisting of formulas Z1, Z2, Z3, Z4, Z5, IV, VI, XII, XIV, XVI, XVIIa, XVIIb, XVIIc, XX, LP1-1, XXIII, XXIX and S and their sub-formulas.

[0514] - The liquid crystal medium contains one or more compounds selected from the formulas II-1, II-2 and II-3, very preferably the compounds selected from the formulas II-1 and II-2. The individual concentration of each of these compounds is preferably 2-15% by weight. The total concentration of these compounds is preferably 5-25% by weight.

[0515] - The liquid crystal medium contains one or more compounds selected from the formulas III-1, III-4, III-6, III-16, III-19 and III-20, very preferably the compounds selected from the formulas III-1, III-6, III-16 and III-20. The individual concentration of each of these compounds is preferably 2-15% by weight. The total concentration of these compounds is preferably 5-30% by weight.

[0516] - The liquid crystal medium contains one or more compounds of formula IV, preferably selected from formula IVa or IVc, very preferably selected from formula IVa-1 or IVc-1, and most preferably formula IVc-1. The individual concentration of each of these compounds is preferably 2-15% by weight. The total concentration of these compounds is preferably 5-20% by weight.

[0517] - The liquid crystal medium contains one or more compounds of formula VI, preferably selected from formula VIb. The individual concentration of each of these compounds is preferably 1-20% by weight. The total concentration of these compounds is preferably 5-20% by weight.

[0518] - The liquid crystal medium contains one or more compounds of formula Z1, preferably selected from formula Z1-1. The total concentration of these compounds is preferably 1-60% by weight, more preferably 5-50% by weight.

[0519] - The liquid crystal medium contains one or more compounds of formula Z2, preferably selected from formula Z2-1 and Z2-2. The total concentration of these compounds is preferably 2-35%, very preferably 3-25% by weight.

[0520] - The liquid crystal medium contains 5-20% by weight of a compound of formula Z3, preferably the compound of formula Z3-1.

[0521] - The liquid crystal medium contains 5-20% by weight of a compound of formula Z4, preferably the compound of formula Z4-1.

[0522] - The liquid crystal medium contains 10-65% by weight, very preferably 20-60% by weight, of a compound of formula Z5.

[0523] - The liquid crystal medium contains one or more compounds of formula LP1-1, preferably the compounds of formula LP1-1a or LP2-1b, very preferably the compound of formula LP1-1a. The concentration of these compounds is preferably 2-15% by weight.

[0524] - The liquid crystal medium contains 1-15% by weight of a compound of formula LP2-1b.

[0525] - The liquid crystal medium contains one or more compounds of formula XII, preferably a compound of formula XIIa or XIIb, very preferably a compound of formula XIIa, and most preferably a compound of formula XIIa-1. The concentration of these compounds is preferably 2-15% by weight.

[0526] - The liquid crystal medium contains 1-15% by weight of a compound of formula XIIb.

[0527] - The liquid crystal medium contains one or more compounds of formula XIV, preferably a compound of formula XIVd, very preferably a compound of formula XIVd-1. The concentration of these compounds is preferably 2-10% by weight.

[0528] - The liquid crystal medium contains one or more compounds of formula XVIb, preferably a compound of formula XVIb-1, XVIb-2 and / or XVIb-3. The concentration of these compounds is preferably 2-15% by weight.

[0529] - The liquid crystal medium contains one or more compounds of formula XVIc, preferably a compound of formula XVIc-1, XVIc-2 and / or XVIc-3. The concentration of these compounds is preferably 2-20% by weight.

[0530] - The liquid crystal medium contains one or more compounds selected from the group consisting of formula XVIIa, XVIIb and XVIIc, very preferably a compound of formula XVIIa where L is H and a compound of formula XVIIb where L is F. The total concentration of these compounds is preferably 0.5-5% by weight.

[0531] - The liquid crystal medium contains one or more compounds of formula XX, preferably a compound of formula XXa. The concentration of these compounds is preferably 2-10% by weight.

[0532] - The liquid crystal medium contains one or more compounds of formula XXI, preferably a compound of formula XXIa. The concentration of these compounds is preferably 2-10% by weight.

[0533] - The liquid crystal medium contains one or more compounds of formula XXIII, preferably a compound of formula XXIIIa. The concentration of these compounds is preferably 0.5-5% by weight.

[0534] - The liquid crystal medium contains one or more compounds of formula XXIX, preferably a compound of formula XXIXa. The concentration of these compounds is preferably 2-10% by weight.

[0535] - The liquid crystal medium contains one or more compounds of formula XXX. The concentration of these compounds is preferably 2-10% by weight.

[0536] - The liquid crystal medium contains one or more compounds of formula XII. The concentration of these compounds is preferably 2-10% by weight.

[0537] - The liquid crystal medium contains one or more compounds of formula I and M (preferably formulae I-1-4-1 and M-2), and LP1 and / or LP2, II and / or III compounds, one or more compounds selected from formulae Z1, Z2 and Z3 or their sub-formulae, one or more compounds selected from formula XIV, one or more compounds selected from formulae IV, VI, XX, XXIII and XXIX or their sub-formulae, and one or more compounds selected from formulae LP2-1, XVI, XVIIa, XVIIb, XVIIc or their sub-formulae.

[0538] - The liquid crystal medium contains one or more compounds of formula I and M (preferably formulae I-1-4-1 and M-2), LP1 and / or LP2, II and / or III compounds, one or more compounds selected from formulae Z1, Z2, Z3, Z4 and Z5 or their sub-formulae, one or more compounds selected from formula XIVd or its sub-formulae, one or more compounds selected from formulae IVc, VIb, XXa, XXIIIa and XXIXa or their sub-formulae, and one or more compounds selected from formulae LP1-1b, XVIb, XVIc, XVIIa, XVIIb, XVIIc or their sub-formulae.

[0539] - The liquid crystal medium contains one or more compounds of formula I and M (preferably formulae I-1-4-1 and M-2), LP1 and / or LP2, II and / or III compounds, one or more compounds selected from formulae Z1, Z2 and Z3 or their sub-formulae, one or more compounds of formula Y, preferably selected from formulae Y1 and Y2, one or more compounds selected from formula XIV, one or more compounds selected from formulae II, III, IV, VI, XX, XXIII and XXIX or their sub-formulae, and one or more compounds selected from formulae LP2-1, XVI, XVIIa, XVIIb, XVIIc or their sub-formulae.

[0540] - The liquid crystal medium contains one or more compounds of formula I and M (preferably formulae I-1-4-1 and M-2), LP1 and / or LP2 compounds, one or more compounds selected from formulae Z1, Z2, Z3, Z4 and Z5 or their sub-formulae, one or more compounds of formula B, preferably selected from formulae B1, B2 and B3, one or more compounds selected from formula XIVd or its sub-formulae, one or more compounds selected from formulae II, III, IVc, VIb, XXa, XXIIIa and XXIXa or their sub-formulae, and one or more compounds selected from formulae LP1-1b, XVIb, XVIc, XVIIa, XVIIb, XVIIc or their sub-formulae.

[0541] - In addition to compounds of formula I and M, LP1 and / or LP2, the liquid crystal medium further comprises other compounds selected from formulae Z1, Z2, Z3, IV, LP1-1, XIV, XVI, XVIIa, XVIIb, XVIIc, XXI, XXIII, XXIX, XXX and XXIV or their sub-formulae.

[0542] - In addition to compounds of formula I and M, LP1 and / or LP2, the liquid crystal medium further comprises other compounds selected from formulae Z1, Z2, Z3, IV, LP2-1, XIV, XVI, XVIIa, XVIIb, XVIIc, XXI, XXIII, XXIX, XXX and XXIV or their sub-formulae.

[0543] - The proportion of compounds of formula I and M or their sub-formulae in the liquid crystal medium is 1-30% by weight, very preferably 2-25% by weight, and most preferably 2-20% by weight.

[0544] - The proportion of compounds of formulae Z1, Z2, Z3, Z4 and Z5 or their sub-formulae in the entire liquid crystal medium is 10-65% by weight, very preferably 20-60% by weight.

[0545] - The proportion of compounds of formula Y or its sub-formulae in the entire liquid crystal medium is 0-15% by weight, very preferably 2-10% by weight.

[0546] - The proportion of compounds of formula B or its sub-formulae in the entire liquid crystal medium is 0-15% by weight, very preferably 2-10% by weight.

[0547] - The proportion of compounds of formulae II, III, IV-VIII, XVIII-XXIII and XXVII-XXX in the entire liquid crystal medium is 30-60% by weight.

[0548] - The proportion of compounds of formulae XIV and XV in the entire liquid crystal medium is 40-70% by weight.

[0549] - The proportion of compounds of formulae XIV, XVIIa-c and XXXII in the entire liquid crystal medium is 0.5-15% by weight.

[0550] In this application, the term "alkyl" or "alkyl * " encompasses straight-chain and branched-chain alkyl groups having 1-6 carbon atoms, especially the straight-chain groups methyl, ethyl, propyl, butyl, pentyl and hexyl. Groups having 2-5 carbon atoms are generally preferred.

[0551] The term "alkenyl" or "alkenyl *”covers straight-chain and branched alkenyl groups having 2 to 6 carbon atoms, especially straight-chain groups. Preferred alkenyl groups are C2-C7-1E-alkenyl, C4-C6-3E-alkenyl, especially C2-C6-1E-alkenyl. Examples of particularly preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl and 5-hexenyl. Groups having at most 5 carbon atoms are generally preferred, especially CH2=CH, CH3CH=CH.

[0552] The term "fluoroalkyl" preferably covers straight-chain groups having a terminal fluorine, i.e., fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl and 7-fluoroheptyl. However, other positions of fluorine are not excluded.

[0553] The term "oxaalkyl" or "alkoxy" preferably covers the formula C n H 2n+1 -O(CH2) m wherein n and m each independently of one another represent 1-6. m can also represent 0. Preferably, n = 1 and m = 1-6 or m = 0 and n = 1-3. Further preferably, the alkoxy or oxaalkyl can also contain one or more other O atoms such that the oxygen atoms are not directly connected to one another.

[0554] The optimal mixing ratio of the compounds of the above formula mainly depends on the desired properties, the selection of the components of the above formula, and the selection of any other components that may be present.

[0555] The appropriate mixing ratio within the above range can be easily determined according to the specific situation.

[0556] The total amount of the compounds of the above formula in the liquid crystal medium according to the invention is not critical. Thus, the liquid crystal medium can contain one or more other components to optimize various properties. However, the higher the total concentration of the compounds of the above formula, the greater the effect generally observed on the desired improvement of the properties of the medium.

[0557] In a particularly preferred embodiment, the liquid crystal medium according to the invention contains compounds of formulas IV to VIII (preferably IV and V), wherein X 0 represents F, OCF3, OCHF2, OCH=CF2, OCF=CF2 or OCF2-CF2H. The favorable synergistic effect with the compounds of formulas I and M, LP1 and / or LP2, II and III results in particularly favorable properties. In particular, the liquid crystal medium containing the compounds of formulas I and M, LP1 and / or LP2, II and III is characterized by its low threshold voltage.

[0558] The individual compounds of the above formula and its sub-formulas which can be used in the liquid crystal medium according to the invention are either known or can be prepared analogously to known compounds.

[0559] The invention also relates to a method for preparing a liquid crystal medium as described above in the context, which method is carried out by mixing one or more compounds of formula I and M with one or more compounds of formula LP1 and / or LP2 and one or more compounds selected from formula II, III, Z1, Z2, Z3, Z4, IV, VI, XIV, LP2-1, XVI, XVIIa, XVIIb, XVIIc, XX, XXIII, XXIX.

[0560] The liquid crystal medium of the invention may optionally contain one or more polymerizable compounds. The polymerizable compounds are preferably selected from formula RM

[0561] R a -B 1 -(Z b -B 2 ) m -R b RM

[0562] wherein each substituent is the same or different at each occurrence and each independently of one another has the following meanings:

[0563] R a and R b are P, P-Sp-, H, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, SF5 or a straight-chain or branched-chain alkyl having 1-25 C atoms, wherein in addition, one or more non-adjacent CH2 groups may each independently of one another be replaced by -C(R 0 )=C(R 00 )-, -C≡C-, -N(R 00 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly connected to each other, and wherein in addition, one or more H atoms may be replaced by F, Cl, Br, I, CN, P or P-Sp-, where, if B 1 and / or B 2 contains saturated C atoms, then R a and / or R b may also represent a group spiro-linked to this saturated C atom,

[0564] wherein at least one of the substituents R a and R b represents or contains the group P or P-Sp-,

[0565] P is a polymerizable group,

[0566] Sp is a spacer group or a single bond,

[0567] B 1 and B 2 is an aromatic, heteroaromatic, alicyclic or heterocyclic group, preferably having 4 - 25 ring atoms, which may also contain fused rings, and which is unsubstituted or mono- or polysubstituted by L,

[0568] Z b is -O-, -S-, -CO-, -CO-O-, -OCO-, -O-CO-O-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -(CH2) n1 -, -CF2CH2-, -CH2CF2-, -(CF2) n1 -, -CH=CH-, -CF=CF-, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, CR 0 R 00 or a single bond,

[0569] R 0 and R 00 each independently of one another represent H or an alkyl group having 1 - 12 C atoms,

[0570] m represents 0, 1, 2, 3 or 4,

[0571] n1 represents 1, 2, 3 or 4,

[0572] L is P, P-Sp-, OH, CH2OH, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x )2, -C(=O)Y 1 , -C(=O)R x , -N(R x )2, an optionally substituted silyl group, an optionally substituted aryl group having 6 - 20 C atoms, or a straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 - 25 C atoms, where in addition one or more H atoms may be substituted by F, Cl, P or P-Sp-,

[0573] P and Sp have the meanings shown in formula RM above,

[0574] Y 1 represents a halogen,

[0575] R xdenote P, P-Sp-, H, halogen, a straight-chain, branched or cyclic alkyl group having 1-25 C atoms, wherein furthermore, one or more non-adjacent CH2 groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly connected to each other, and furthermore, one or more H atoms may be replaced by F, Cl, P or P-Sp-, an optionally substituted aryl or aryloxy group having 6-40 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2-40 C atoms.

[0576] Further preferably, the liquid crystal medium according to the invention comprises one or more polymerizable compounds selected from Table H below.

[0577] Preferably, the proportion of the polymerizable compound in the liquid crystal medium is 0.01-5%, very preferably 0.05-1%, and most preferably 0.1-0.5%. The polymerizable compound is preferably selected from formula RM and Table H.

[0578] It has been observed that adding one or more polymerizable compounds, such as those selected from formula RM and Table H, to the liquid crystal medium results in advantageous properties such as fast response times. Such liquid crystal media are particularly suitable for PSA displays, where they exhibit low image sticking, fast and complete polymerization, rapid generation of a low pretilt angle that is stable after UV exposure, high reliability, high VHR values after UV exposure, and high birefringence. By appropriately selecting the polymerizable compound, the absorption of the liquid crystal medium at longer UV wavelengths can be increased, such that this longer UV wavelength can be used for polymerization, which is advantageous for display manufacturing methods.

[0579] The polymerizable group P is suitable for polymerization reactions, such as free radical or ionic chain polymerization, addition polymerization or condensation polymerization, or is suitable for reactions similar to polymers, such as addition or condensation on the polymer backbone. Particularly preferred are groups for chain polymerization, especially those containing a C═C double bond or a -C≡C- triple bond, and groups suitable for ring-opening polymerization, such as oxetanyl or epoxy groups.

[0580] Preferred P groups are selected from the group: CH2═CW 1 -CO-O-, CH2═CW 1 -CO-, CH2═CW 2 -(O) k3 -, CW 1 ═CH-CO-(O) k3 -, CW 1 ═CH-CO-NH-, CH2═CW 1-CO-NH-, CH3-CH=CH-O-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, HO-CW 2 W 3 -, HS-CW 2 W 3 -, HW 2 N-, HO-CW 2 W 3 -NH-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -, CH2=CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH-, HOOC-, OCN- and W 4 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF3, phenyl or an alkyl group having 1 to 5 C atoms, especially H, F, Cl or CH3, W 2 and W 3 each independently of one another represents H or an alkyl group having 1 - 5 carbon atoms, especially H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently of one another represents Cl, an oxaalkyl or an oxacarbonylalkyl group having 1 to 5 C atoms, W 7 and W 8 each independently of one another represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, which is optionally substituted by one or more substituents L as defined above for the formula RM, the group L not being P-Sp-, k1, k2 and k3 each independently of one another represent 0 or 1, k3 preferably represents 1, and k4 represents an integer from 1 - 10.

[0581] Very preferably, the P groups are selected from the group consisting of: CH2=CW 1 -CO-O-, CH2=CW 1 -CO-, CH2=CW 2 -O-, CH2=CW 2 -, CW 1 =CH-CO-(O) k3 -, CW 1 =CH-CO-NH-, CH2=CW1 -CO-NH-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -, CH2=CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH- and W 4 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF3, phenyl or an alkyl group having 1 to 5 C atoms, especially H, F, Cl or CH3, W 2 and W 3 each independently of one another represents H or an alkyl group having 1 to 5 C atoms, especially H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently of one another represents Cl, an oxaalkyl group or an oxacarbonylalkyl group having 1 to 5 C atoms, W 7 and W 8 each independently of one another represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, k1, k2 and k3 each independently of one another represent 0 or 1, k3 preferably represents 1, and k4 represents an integer from 1 to 10.

[0582] Very particularly preferred P groups are selected from the group: CH2=CW 1 -CO-O-, especially CH2=CH-CO-O-, CH2=C(CH3)-CO-O- and CH2=CF-CO-O-, and CH2=CH-O-, (CH2=CH)2CH-O-CO-, (CH2=CH)2CH-O-, and

[0583] Further preferred polymerizable groups P are selected from the group: vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetanyl and epoxy, most preferably selected from acrylate and methacrylate.

[0584] If Sp is different from a single bond, it is preferably of the formula Sp"-X", so that the corresponding substituent P-Sp- conforms to the formula P-Sp"-X", where,

[0585] "Sp" represents an alkylene group having 1 to 20 C atoms, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, and in which furthermore, one or more non-adjacent CH2 groups may each independently of one another be replaced by -O-, -S-, -NH-, -N(R 0 )-, -Si(R 0 R 00 )-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -S-CO-, -CO-S-, -N(R 00 )-CO-O-, -O-CO-N(R 0 )-, -N(R 0 )-CO-N(R 00 )-, -CH=CH- or -C≡C- in such a way that O and / or S atoms are not directly connected to each other,

[0586] "X" represents -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CO-N(R 0 )-, N(R 0 )-CO-, -N(R 0 )-CO-N(R 00 )-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, CF2O-, -OCF2-, -CF2S-, -SCF2-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CR 0 -, -CY 2 =CY 3 -, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH- or a single bond,

[0587] R 0 and R 00 each independently of one another represent H or an alkyl group having 1 to 20 C atoms, and

[0588] Y 2 and Y 3 each independently of one another represent H, F, Cl or CN.

[0589] X" is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -, -NR 0 -CO-, -NR 0 -CO-NR 00 - or a single bond.

[0590] Typical spacer groups Sp and -Sp"-X" are, for example, -(CH2) p1 -, -(CH2CH2O) q1 -CH2CH2-, -CH2CH2-S-CH2CH2-, -CH2CH2-NH-CH2CH2- or -(SiR 0 R 00 -O) p1 -, where p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R 0 and R 00 have the meanings shown in formula RM above.

[0591] Particularly preferred groups Sp and -Sp"-X" are -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -O-CO-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO-O-, where p1 and q1 have the above meanings.

[0592] Particularly preferred groups Sp" are, in each case, straight-chain ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethyl-N-methylimino-ethylene, 1-methylalkylene, vinylidene, propenylene, and butenylene.

[0593] For the production of PSA displays, the polymerizable compounds contained in the liquid-crystalline medium are polymerized or crosslinked (if a compound contains two or more polymerizable groups) in the liquid-crystalline medium between the substrates of the LC display by in-situ polymerization, optionally while applying a voltage to the electrodes.

[0594] The structure of the PSA display according to the invention corresponds to the usual geometry of PSA displays, as described in the prior art cited at the beginning. A geometry without protrusions is preferred, especially those in which the electrodes on the color filter side are additionally unstructured and only the electrodes on the TFT side have grooves. Particularly suitable and preferred electrode structures for PS-VA displays are described, for example, in US2006 / 0066793 A1.

[0595] The combination of the compounds of the above preferred embodiments with the above polymerized compounds results in a low threshold voltage, low rotational viscosity, and very good low-temperature stability in the liquid-crystalline medium according to the invention, while producing constant high-definition bright dots and high VHR values.

[0596] A liquid crystal medium containing a polymerizable compound is used to rapidly establish a particularly low pretilt angle in a PSA display. In particular, compared with the media of the prior art, in a PSA display, the liquid crystal medium exhibits a significantly shortened response time, especially for the gray-scale response time.

[0597] A liquid crystal medium having a nematic LC phase is generally preferred, and a chiral liquid crystal phase is preferably not present.

[0598] The invention also relates to the use of a liquid crystal medium according to the invention as described in the context for electro-optical purposes, in particular for shutter glasses, for 3D applications, in TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, positive VA and positive PS-VA displays, and to an electro-optical display, in particular a display of the aforementioned types, which contains a liquid crystal medium according to the invention as described in the context, in particular a TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, positive VA (vertical alignment) or positive PS-VA display.

[0599] The invention also relates to an electro-optical display, such as an STN or matrix LC (MLC) display, which has two plane-parallel outer plates that together with a frame form a cell, an integrated non-linear element for switching individual pixels on the outer plates, and a nematic liquid crystal medium having a positive dielectric anisotropy and a high resistivity located in the cell, wherein the nematic liquid crystal medium is a liquid crystal medium according to the invention as described in the context.

[0600] The liquid crystal medium according to the invention enables a significant broadening of the available parameter range. The achievable combination of clearing point, low-temperature viscosity, thermal and UV stability and high optical anisotropy is far superior to the prior materials of the prior art.

[0601] In particular, the combination of compounds of formula I and M with compounds of formula LP1 and / or LP2 and optionally with compounds selected from formulae II-XXXII or their sub-formulae results in a liquid crystal medium that exhibits a medium positive dielectric anisotropy while increasing the dielectric constant ε⊥ perpendicular to the longitudinal axis of the LC molecules, while maintaining a low rotational viscosity and a low value of the ratio γ1 / K1. This enables the realization of energy-saving LC displays, in particular FFS, HB-FFS, XB-FFS and IPS modes, energy-saving LC displays with high brightness and transmittance and low response time.

[0602] The liquid crystal medium according to the invention is suitable for fast-switching gaming mixtures, such as televisions and monitors. In addition, the liquid crystal medium according to the invention is particularly suitable for FFS, HB-FFS, XB-FFS and IPS displays based on dielectrically positive liquid crystals.

[0603] The liquid crystal medium according to the invention allows to obtain a rotational viscosity γ1 ≤ 100 mPa·s, particularly preferably ≤ 80 mPa·s, while maintaining a nematic phase down to -20 °C, preferably down to -30 °C, particularly preferably down to -40 °C, and a clearing point ≥ 70 °C, preferably ≥ 75 °C, enabling the obtaining of an excellent MLC display with a fast response time. The rotational viscosity is measured at 20 °C.

[0604] The dielectric anisotropy Δε of the liquid crystal medium according to the invention at 20 °C and 1 kHz is preferably ≥ +1.5, more preferably from +3 to +18, and most preferably from +5 to +15.

[0605] The birefringence Δn of the liquid crystal medium according to the invention at 20 °C is preferably from 0.08 to 0.2, very preferably from 0.09 to 0.15.

[0606] The rotational viscosity γ1 of the liquid crystal medium according to the invention is preferably ≤ 120 mPa·s, more preferably ≤ 110 mPa·s, and very preferably ≤ 90 mPa·s.

[0607] The ratio γ1 / K1 of the liquid crystal medium according to the invention (where γ1 is the rotational viscosity and K1 is the elastic constant of splay deformation) is preferably ≤ 7 mPa·s / pN, very preferably ≤ 6 mPa·s / pN, and most preferably ≤ 5.5 mPa·s / pN.

[0608] The average elastic constant ratio K of the liquid crystal medium according to the invention av is preferably at least 14.0 pN, very preferably at least 15.0 pN, and most preferably at least 16.0 pN. K av can be calculated according to the following formula: K av = (K1 + K2 + K3) / 3 ≈ (K1 + 1 / 2*K1 + K3) / 3.

[0609] The nematic phase range of the liquid crystal medium according to the invention preferably has a width of at least 90 °C, more preferably at least 100 °C, especially at least 110 °C. This range preferably extends from -25 °C to +90 °C.

[0610] It goes without saying that by appropriately selecting the components of the liquid crystal medium according to the present invention, it is also possible to achieve a higher clearing point (e.g., above 100 °C) at a higher threshold voltage, or a lower clearing point at a lower threshold voltage, while maintaining other advantageous properties. A liquid crystal medium having a higher Δε and thus a low threshold can also be obtained when the viscosity is increased only slightly accordingly. The MLC display according to the present invention preferably operates at the first Gooch and Tarry transmission minimum, [C.H. Gooch and H.A. Tarry, Electron. Lett. 10, 24, 1974; C.H. Gooch and H.A. Tarry, Appl. Phys., Vol. 8, 1575 - 1584, 1975], where, in addition to particularly advantageous electro-optical properties, such as the high steepness of the characteristic line and the low angular dependence of the contrast (German Patent 30 22 818), a lower dielectric anisotropy is sufficient at the same threshold voltage as in a similar display at the second minimum. This enables a significantly higher resistivity value to be achieved at the first minimum when using the liquid crystal medium according to the present invention compared to the case of a liquid crystal medium containing a cyanide compound. By appropriately selecting the individual components and their weight ratios, a person skilled in the art can set the birefringence required for a predetermined layer thickness of the MLC display using simple conventional methods.

[0611] Measurements of the voltage holding ratio (HR) [S. Matsumoto et al., Liquid Crystals 5, 1320 (1989); K. Niwa et al., Proc. SID Conference, San Francisco, June 1984, p. 304 (1984); G. Weber et al., Liquid Crystals 5, 1381 (1989)] have shown that the liquid crystal medium according to the present invention containing compounds of formula ST-1, ST-2, RV, IA and IB shows a significantly smaller reduction in HR upon UV exposure compared to a similar liquid crystal medium containing a cyanophenylcyclohexane of formula or an ester of formula .

[0612] The light stability and UV stability of the liquid crystal medium according to the present invention are significantly better, i.e., the reduction in HR upon exposure to light, heat or UV is significantly smaller.

[0613] The construction of the MLC display according to the present invention consists of a polarizer, an electrode substrate and a surface-treated electrode, which corresponds to the usual design of this type of display. The term usual design is broadly depicted herein and also includes all derivative forms and modified forms of the MLC display, particularly including matrix display elements based on polysilicon TFTs or MIMs.

[0614] However, a significant difference between the display according to the present invention and the conventional displays based on twisted nematic cells to date lies in the selection of the LC parameters of the LC layer.

[0615] The liquid crystal medium useful according to the present invention can be prepared in a conventional manner per se, for example, by mixing one or more compounds of claim 1 with one or more compounds of formulae II - XXXII or with other LC compounds and / or additives. Generally, advantageously at an elevated temperature, the required amounts of the components used in smaller amounts are dissolved in the components constituting the main ingredient. The solutions of the components can also be mixed in an organic solvent such as acetone, chloroform or methanol, and after thorough mixing, the solvent is removed again, for example, by distillation.

[0616] The liquid crystal medium can also contain other additives known to those skilled in the art and described in the literature, such as polymerization initiators, inhibitors, surface active substances, light stabilizers, antioxidants such as BHT, TEMPOL, microparticles, radical scavengers, nanoparticles, etc. For example, 0 - 15 wt% of a dichroic dye or a chiral dopant or an initiator (such as 651 or 907) can be added. Suitable stabilizers and dopants are mentioned in Tables F and G below. In a preferred embodiment, the liquid crystal medium contains one or more stabilizers selected from Table G. Preferably, the proportion of the stabilizer (such as the formulae ST and H as described above or the stabilizers listed in Table G) in the liquid crystal medium is 10 - 2000 ppm, very preferably 30 - 1000 ppm.

[0617] In addition, for example, 0 - 15 wt% of a dichroic dye, as well as nanoparticles and conductive salts, preferably ethyl dimethyldodecylammonium 4 - hexoxybenzoate, tetrabutylammonium tetraphenylborate or complex salts of crown ethers (for example, see Haller et al., Mol. Cryst. Liq. Cryst. 24 , 249 - 258 (1973)) can be added to the liquid crystal medium for changing the conductivity or substances for changing the dielectric anisotropy, viscosity and / or the alignment of the nematic phase. Substances of this type are described, for example, in DE - A22 09 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 28 53 728.

[0618] For the present invention and in the following examples, the structures of the LC compounds are represented by acronyms and converted into chemical formulae according to Tables A to C below. All substituents C m H 2m+1 C n H 2n+1 and Cl H 2l+1 or C m H 2m-1 、C n H 2n-1 and C l H 2l-1 are straight-chain alkyl or alkylene groups, each having n, m, and l C atoms in each case. Preferably, n, m, and l independently of one another represent 1, 2, 3, 4, 5, 6, or 7. Table A shows the codes for the ring elements of the compound nucleus, Table B lists the bridging units, and Table C lists the symbolic meanings of the molecular left- and right-hand end groups. The acronyms consist of the code for the ring element with an optional linking group, followed by a first hyphen and the left-hand end group code, and a second hyphen and the right-hand end group code. Table D shows the exemplary structures of the compounds and their respective abbreviations.

[0619] Table A: Ring elements

[0620]

[0621]

[0622]

[0623]

[0624] Table B: Bridging units

[0625]

[0626] Table C: End groups

[0627]

[0628]

[0629] wherein n and m are each integers, and the three dots "..." are placeholders for other abbreviations from the table.

[0630] The following abbreviations are used:

[0631] (n, m, k, and l are each independently of one another integers, preferably 1 - 12, preferably 1 - 6, k and l can also be 0, preferably 0 - 4, more preferably 0 or 2, most preferably 2, n is preferably 1, 2, 3, 4, or 5, and in the combination "-nO-", it is preferably 1, 2, 3, or 4, very preferably 2 or 4, m is preferably 1, 2, 3, 4, or 5, and in the combination "-Om", it is preferably 1, 2, 3, or 4, more preferably 2 or 4. The combination "-lVm" is preferably "2V1".)

[0632] Preferred components of the liquid crystal medium are shown in Tables D and E.

[0633] Table D

[0634]

[0635]

[0636]

[0637]

[0638]

[0639] Table E

[0640] In the following formula, n and m each independently of one another represent 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, in particular 2, 3, 5, and also 0, 4, 6.

[0641]

[0642]

[0643]

[0644]

[0645]

[0646]

[0647]

[0648]

[0649]

[0650]

[0651]

[0652]

[0653]

[0654]

[0655]

[0656]

[0657]

[0658]

[0659] Particularly preferred liquid crystal media contain, in addition to compounds of formula I, M, LP1 and / or LP2, at least one, two, three, four or more compounds from Table E.

[0660] Table F

[0661] Table F lists possible dopants which are customarily added to liquid crystal media according to the invention. The liquid crystal media preferably contain 0 - 10% by weight, in particular 0.01 - 5% by weight, particularly preferably 0.01 - 3% by weight, of dopant.

[0662]

[0663]

[0664] Table G

[0665] The following stabilizers which can additionally be added to the liquid crystal media according to the invention are mentioned, for example in an amount of 0 - 10% by weight.

[0666]

[0667] n = 1, 2, 3, 4, 5, 6 or 7

[0668]

[0669] n = 1, 2, 3, 4, 5, 6 or 7

[0670]

[0671] n = 1, 2, 3, 4, 5, 6 or 7 q = 1, 2, 3, 4, 5, 6 or 7

[0672]

[0673]

[0674]

[0675]

[0676]

[0677] Table H

[0678] Table H shows exemplary reactive mesogenic compounds (RMs) that can be used in the liquid crystal medium according to the present invention.

[0679]

[0680]

[0681]

[0682]

[0683]

[0684]

[0685]

[0686]

[0687]

[0688]

[0689]

[0690]

[0691]

[0692]

[0693]

[0694]

[0695]

[0696]

[0697]

[0698]

[0699]

[0700]

[0701]

[0702]

[0703]

[0704] The liquid crystal medium according to the invention may optionally contain one or more polymerizable compounds, preferably selected from the polymerizable compounds of formulae RM-1 to RM-184. Among these compounds, 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-184 are particularly preferred.

[0705] Table I

[0706] Table I shows the self-aligning additives for vertical alignment, which can be used in the liquid crystal medium for SA-FFS, SA-HB-FFS and SA-XB-FFS displays according to the invention:

[0707]

[0708]

[0709]

[0710]

[0711]

[0712]

[0713]

[0714]

[0715]

[0716]

[0717]

[0718]

[0719]

[0720] In a preferred embodiment, the liquid crystal medium, SA-VA and SA-FFS displays according to the invention comprise one or more SA additives selected from formulas SA-1 to SA-49, preferably from formulas SA-14 to SA-49, very preferably from formulas SA-20 to SA-34 and SA-44, in combination with one or more RMs.

[0721] The following examples are intended to illustrate the invention and not to limit it.

[0722] The percentage data above and below represent weight percentages. All temperatures are in degrees Celsius. m.p. represents melting point, cl.p. = clearing point. Furthermore, C = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The data between these symbols represent transition temperatures. Furthermore, the following symbols are used,

[0723] V0 Fredericks threshold voltage at 20 °C, capacitive [V],

[0724] V 10 Voltage for 10% transmittance [V],

[0725] n e Represents the extraordinary refractive index at 20 °C and 589 nm,

[0726] n o Represents the ordinary refractive index at 20 °C and 589 nm,

[0727] Δn represents the optical anisotropy at 20 °C and 589 nm,

[0728] ε ⊥ Dielectric polarizability (or "dielectric constant") perpendicular to the longitudinal molecular axis at 20 °C and 1 kHz,

[0729] ε || Dielectric polarizability (or "dielectric constant") parallel to the longitudinal molecular axis at 20 °C and 1 kHz,

[0730] Δε Dielectric anisotropy at 20 °C and 1 kHz,

[0731] cl.p. or T(N,I) Clearing point [°C],

[0732] ν Flow viscosity measured at 20 °C [mm 2 ·s -1 ,

[0733] γ1 Rotational viscosity measured at 20 °C [mPa×s],

[0734] K1 Elastic constant, "splay" deformation at 20 °C [pN],

[0735] K2 Elastic constant, "twist" deformation at 20 °C [pN],

[0736] K3 Elastic constant, "bend" deformation at 20 °C [pN], and

[0737] VHR Voltage holding ratio.

[0738] Unless otherwise explicitly stated, all physical properties are determined according to "Merck Liquids Crystal, Physical Properties of Liquid Crystals", Status Nov. 1997, Merck KGaA, Germany and apply to a temperature of 20 °C. Detailed implementation mode

[0739] Examples

[0740] Example M1

[0741] Prepare a nematic liquid crystal medium as follows:

[0742]

[0743]

[0744] K of the LC mixture av is 13.95 pN and γ1 / K1 is 3.22 mPa·s / pN.

[0745] Mixture Example S1 (stabilized with compound of formula H-3-3)

[0746] Prepare a nematic LC mixture according to the present invention as follows:

[0747] Mixture M1 99.9 wt.-% Compound of formula H-3-3 1000 ppm

[0748] Compared with the unstabilized mixture M1, adding 1000 ppm of the compound of formula H-3-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M1.

[0749]

[0750] Example M2

[0751] Prepare a nematic liquid crystal medium as follows:

[0752]

[0753]

[0754] The K of the LC mixture av is 14.57 pN and γ1 / K1 is 3.21 mPa·s / pN.

[0755] Mixture Example S2 (stabilized with compound of formula H-3-5)

[0756] A nematic LC mixture according to the present invention is formulated as follows:

[0757] Mixture M2 99.995 wt.-% Compound of formula H-3-5 50 ppm

[0758] Compared with the unstabilized mixture M2, the addition of 50 ppm of the compound of formula H-3-5 significantly improves the VHR after UV exposure 100 without affecting the remaining physical properties of the mixture M2.

[0759]

[0760] Example M3

[0761] A nematic liquid crystal medium is formulated as follows:

[0762]

[0763] The K of the LC mixture av is 14.22 pN and γ1 / K1 is 3.06 mPa·s / pN.

[0764] Mixture Example S3 (stabilized with compound of formula ST-1-3)

[0765] A nematic LC mixture according to the present invention is formulated as follows:

[0766] Mixture M3 99.95 wt.-% Compound of formula ST-1-3 500 ppm

[0767] Compared with the unstabilized mixture M3, the addition of 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 without affecting the remaining physical properties of the mixture M3.

[0768]

[0769] Mixture Example S3a (stabilized with compound of formula ST-1-8)

[0770] A nematic LC mixture according to the present invention is formulated as follows:

[0771] Mixture M3 99.96 wt.-% Compound of formula ST-1-8 400 ppm

[0772] Compared with the non-stabilized mixture M3, the addition of 400 ppm of the compound of formula ST-1-8 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M3.

[0773]

[0774] Example M4

[0775] A nematic liquid crystal medium is formulated as follows:

[0776]

[0777]

[0778] The K of the LC mixture av is 13.97 pN and γ1 / K1 is 3.15 mPa·s / pN.

[0779] Mixture Example S4 (stabilized with compound of formula H-3-1)

[0780] A nematic LC mixture according to the present invention is formulated as follows:

[0781] Mixture M4 99.9 wt.-% Compound of formula H-3-1 1000 ppm

[0782] Compared with the non-stabilized mixture M4, the addition of 1000 ppm of the compound of formula H-3-1 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M4.

[0783]

[0784] Example M5

[0785] A nematic liquid crystal medium is formulated as follows:

[0786]

[0787]

[0788] The K of the LC mixture av is 14.85 pN and γ1 / K1 is 3.37 mPa·s / pN.

[0789] Mixture Example S5 (stabilized with compound of formula ST-2-3)

[0790] A nematic LC mixture according to the present invention is formulated as follows:

[0791] Mixture M5 99.95 wt.-% Compound of formula ST-2-3 500 ppm

[0792] Compared with the unstabilized mixture M5, adding 500 ppm of the compound of formula ST-2-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M5.

[0793]

[0794] Mixture Example S5a (stabilized with compound of formula ST-2-8)

[0795] The nematic LC mixture according to the present invention is formulated as follows:

[0796] Mixture M5 99.95 wt.-% Compound of formula ST-2-8 500 ppm

[0797] Compared with the unstabilized mixture M5, adding 500 ppm of the compound of formula ST-2-8 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M5.

[0798]

[0799] Example M6

[0800] The nematic liquid crystal medium is formulated as follows:

[0801]

[0802]

[0803] The K of the LC mixture av is 14.30 pN and γ1 / K1 is 3.02 mPa·s / pN.

[0804] Mixture Example S6 (stabilized with compound of formula H-3-1)

[0805] The nematic LC mixture according to the present invention is formulated as follows:

[0806] Mixture M6 99.9 wt.-% Compound of formula H-3-1 1000 ppm

[0807] Compared with the unstabilized mixture M6, adding 1000 ppm of the compound of formula H-3-1 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M6.

[0808] Example M7

[0809] The nematic liquid crystal medium is formulated as follows:

[0810]

[0811]

[0812] The K of the LC mixture av is 14.30 pN and γ1 / K1 is 3.10 mPa·s / pN.

[0813] Mixture Example S7 (stabilized with compound of formula ST-2-3)

[0814] A nematic LC mixture according to the present invention is formulated as follows:

[0815] Mixture M7 99.95 wt.-% Compound of formula ST-2-3 500 ppm

[0816] Compared with the non-stabilized mixture M7, adding 500 ppm of the compound of formula ST-2-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M7.

[0817] Example M8

[0818] A nematic liquid crystal medium is formulated as follows:

[0819]

[0820]

[0821] The K of the LC mixture av is 14.00 pN and γ1 / K1 is 3.20 mPa·s / pN.

[0822] Mixture Example S8 (stabilized with compound of formula ST-1-3)

[0823] A nematic LC mixture according to the present invention is formulated as follows:

[0824] Mixture M8 99.95 wt.-% Compound of formula ST-1-3 500 ppm

[0825] Compared with the non-stabilized mixture M8, adding 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M8.

[0826] Example M9

[0827] A nematic liquid crystal medium is formulated as follows:

[0828]

[0829] The K of the LC mixture av is 14.17 pN and γ1 / K1 is 3.43 mPa·s / pN.

[0830] Mixture Example S9 (stabilized with compound of formula H-3-1)

[0831] A nematic LC mixture according to the present invention is formulated as follows:

[0832] Mixture M9 99.9 wt.-% Compound of formula H-3-1 1000 ppm

[0833] Compared with the unstabilized mixture M9, the addition of 1000 ppm of the compound of formula H-3-1 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M9.

[0834] Example M10

[0835] A nematic liquid crystal medium is formulated as follows:

[0836]

[0837] Mixture Example S10 (stabilized with compound of formula H-3-2)

[0838] A nematic LC mixture according to the present invention is formulated as follows:

[0839] Mixture M10 99.995 wt.-% Compound of formula H-3-2 50 ppm

[0840] Compared with the unstabilized mixture M10, the addition of 50 ppm of the compound of formula H-3-2 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M10.

[0841]

[0842] Example M11

[0843] A nematic liquid crystal medium is formulated as follows:

[0844]

[0845] Mixture Example S11 (stabilized with compound of formula H-3-4). The nematic LC mixture according to the invention is prepared as follows: Mixture:

[0846]

[0847]

[0848] Compared with the unstabilized mixture M11, the addition of 100 ppm of the compound of formula H-3-4 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M11.

[0849]

[0850] Example M12

[0851] A nematic liquid crystal medium is formulated as follows:

[0852]

[0853] Mixture Example S12 (stabilized with compound of formula H-3-6)

[0854] A nematic LC mixture according to the present invention is formulated as follows:

[0855] Mixture M12 99.995 wt.-% Compound of formula H-3-6 50 ppm

[0856] Compared with the unstabilized mixture M12, the addition of 50 ppm of the compound of formula H-3-6 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M12.

[0857]

[0858] Example M13

[0859] A nematic liquid crystal medium is formulated as follows:

[0860]

[0861]

[0862] Mixture Example S13 (stabilized with compound of formula H-3-7)

[0863] A nematic LC mixture according to the present invention is formulated as follows:

[0864] Mixture M13 99.95 wt.-% Compound of formula H-3-7 500 ppm

[0865] Compared with the unstabilized mixture M13, the addition of 500 ppm of the compound of formula H-3-7 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M13.

[0866]

[0867] Example M14

[0868] A nematic liquid crystal medium is formulated as follows:

[0869]

[0870]

[0871] The K of the LC mixture av is 14.6 pN and γ1 / K1 is 3.21 mPa·s / pN.

[0872] Mixture Example S14 (stabilized with compound of formula H-3-8)

[0873] A nematic LC mixture according to the invention is formulated as follows:

[0874] Mixture M14 99.95 wt.-% Compound of formula H-3-8 500 ppm

[0875] Compared with the non-stabilized mixture M14, the addition of 500 ppm of the compound of formula H-3-8 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M14.

[0876]

[0877] Example M15

[0878] A nematic liquid crystal medium is formulated as follows:

[0879]

[0880] Mixture Example S15 (stabilized with compound of formula H-3-9)

[0881] A nematic LC mixture according to the invention is formulated as follows:

[0882] Mixture M15 99.995 wt.-% Compound of formula H-3-9 50 ppm

[0883] Compared with the non-stabilized mixture M15, the addition of 50 ppm of the compound of formula H-3-9 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M15.

[0884]

[0885] Example M16

[0886] A nematic liquid crystal medium is formulated as follows:

[0887]

[0888]

[0889] Mixture Example S16 (stabilized with compound of formula H-3-10)

[0890] A nematic LC mixture according to the invention is formulated as follows:

[0891] Mixture M16 99.995 wt.-% Compound of formula H-3-10 50 ppm

[0892] Compared with the non-stabilized mixture M16, the addition of 50 ppm of the compound of formula H-3-10 significantly improves the VHR after UV exposure 100, without affecting the remaining physical properties of the mixture M16.

[0893]

[0894] Example M17

[0895] A nematic liquid crystal medium is prepared as follows:

[0896]

[0897]

[0898] Mixture Example S17 (stabilized with compound of formula H-3-11)

[0899] A nematic LC mixture according to the present invention is prepared as follows:

[0900] Mixture M17 99.995 wt.-% Compound of formula H-3-11 50 ppm

[0901] Compared with the non-stabilized mixture M17, the addition of 50 ppm of the compound of formula H-3-11 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M17.

[0902]

[0903] Example M18

[0904] A nematic liquid crystal medium is prepared as follows:

[0905]

[0906]

[0907] Mixture Example S18 (stabilized with compound of formula H-3-12)

[0908] A nematic LC mixture according to the present invention is prepared as follows:

[0909] Mixture M18 99.995 wt.-% Compound of formula H-3-12 50 ppm

[0910] Compared with the non-stabilized mixture M18, the addition of 50 ppm of the compound of formula H-3-12 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M18.

[0911]

[0912] Example M19

[0913] A nematic liquid crystal medium is prepared as follows:

[0914]

[0915]

[0916] Mixture Example S19 (stabilized with compound of formula H-3-13)

[0917] A nematic LC mixture according to the invention is formulated as follows:

[0918] Mixture M19 99.995 wt.-% Compound of formula H-3-13 50 ppm

[0919] Compared with the unstabilized mixture M19, the addition of 50 ppm of the compound of formula H-3-13 significantly improves the VHR after UV exposure 100 without affecting the remaining physical properties of the mixture M19.

[0920]

[0921] Example M20

[0922] A nematic liquid crystal medium is formulated as follows:

[0923]

[0924]

[0925] Mixture Example S20 (stabilized with compound of formula H-3-14)

[0926] A nematic LC mixture according to the invention is formulated as follows:

[0927] Mixture M20 99.995 wt.-% Compound of formula H-3-14 50 ppm

[0928] Compared with the unstabilized mixture M20, the addition of 50 ppm of the compound of formula H-3-14 significantly improves the VHR after UV exposure 100 without affecting the remaining physical properties of the mixture M20.

[0929]

[0930] Example M21

[0931] A nematic liquid crystal medium is formulated as follows:

[0932]

[0933]

[0934] Mixture Example S21 (stabilized with compound of formula ST-4-1)

[0935] A nematic LC mixture according to the invention is formulated as follows:

[0936] Mixture M21 99.96 wt.-% Compound of formula ST-4-1 400 ppm

[0937] Compared with the non-stabilized mixture M21, adding 400 ppm of the compound of formula ST-4-1 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M21.

[0938]

[0939] Example M22

[0940] A nematic liquid crystal medium is formulated as follows:

[0941]

[0942]

[0943] Mixture Example S22 (stabilized with compound of formula ST-4-2)

[0944] A nematic LC mixture according to the present invention is formulated as follows:

[0945] Mixture M22 99.96 wt.-% Compound of formula ST-4-2 400 ppm

[0946] Compared with the non-stabilized mixture M22, adding 400 ppm of the compound of formula ST-4-2 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M22

[0947]

[0948] Example M23

[0949] A nematic liquid crystal medium is formulated as follows:

[0950]

[0951]

[0952] Mixture Example S23 (stabilized with compound of formula ST-1-3)

[0953] A nematic LC mixture according to the present invention is formulated as follows:

[0954] Mixture M23 99.95 wt.-% Compound of formula ST-1-3 500 ppm

[0955] Compared with the non-stabilized mixture M23, adding 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M23.

[0956] Example M24

[0957] A nematic liquid crystal medium is prepared as follows:

[0958]

[0959]

[0960] Mixture Example S24 (stabilized with compound of formula ST-1-3)

[0961] A nematic LC mixture according to the present invention is prepared as follows:

[0962] Mixture M24 99.95 wt.-% Compound of formula ST-1-3 500 ppm

[0963] Compared with the unstabilized mixture M24, adding 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M24.

[0964] Example M25

[0965] A nematic liquid crystal medium is prepared as follows:

[0966]

[0967]

[0968] Mixture Example S25 (stabilized with compound of formula ST-1-3)

[0969] A nematic LC mixture according to the present invention is prepared as follows:

[0970] Mixture M25 99.95 wt.-% Compound of formula ST-1-3 500 ppm

[0971] Compared with the unstabilized mixture M25, adding 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M25.

[0972] Example M26

[0973] A nematic liquid crystal medium is prepared as follows:

[0974]

[0975]

[0976] Mixture Example S26 (stabilized with compound of formula ST-1-3)

[0977] A nematic LC mixture according to the present invention is formulated as follows:

[0978] Mixture M26 99.95 wt.-% Compound of formula ST-1-3 500 ppm

[0979] Compared with the non-stabilized mixture M26, the addition of 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M26.

[0980] Example M27

[0981] A nematic liquid crystal medium is formulated as follows:

[0982]

[0983]

[0984] Mixture Example S27 (stabilized with compound of formula ST-1-3)

[0985] A nematic LC mixture according to the present invention is formulated as follows:

[0986] Mixture M27 99.95 wt.-% Compound of formula ST-1-3 500 ppm

[0987] Compared with the non-stabilized mixture M27, the addition of 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M27.

[0988] Example M28

[0989] A nematic liquid crystal medium is formulated as follows:

[0990]

[0991]

[0992]

[0993] Mixture Example S28 (stabilized with compound of formula ST-1-3)

[0994] A nematic LC mixture according to the present invention is formulated as follows:

[0995] Mixture M28 99.95 wt.-% Compound of formula ST-1-3 500 ppm

[0996] Compared with the non-stabilized mixture M28, the addition of 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M28.

[0997] Example M29

[0998] The nematic liquid crystal medium is formulated as follows:

[0999]

[1000]

[1001]

[1002] Mixture Example S29 (stabilized with compound of formula ST-1-3)

[1003] The nematic LC mixture according to the present invention is formulated as follows:

[1004] Mixture M29 99.95 wt.-% Compound of formula ST-1-3 500 ppm

[1005] Compared with the non-stabilized mixture M29, the addition of 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 without affecting the remaining physical properties of the mixture M29.

[1006] Example M30

[1007] The nematic liquid crystal medium is formulated as follows:

[1008]

[1009]

[1010] Mixture Example S30 (stabilized with compound of formula ST-1-3)

[1011] The nematic LC mixture according to the present invention is formulated as follows:

[1012]

[1013] Compared with the non-stabilized mixture M30, the addition of 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 without affecting the remaining physical properties of the mixture M30.

[1014] Example M31

[1015] The nematic liquid crystal medium is formulated as follows:

[1016]

[1017]

[1018] Mixture Example S31 (stabilized with compound of formula ST-1-3)

[1019] A nematic LC mixture according to the present invention is formulated as follows:

[1020] Mixture M31 99.95 wt.-% Compound of formula ST-1-3 500 ppm

[1021] Compared with the non-stabilized mixture M31, adding 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M31.

[1022] Example M32

[1023] A nematic liquid crystal medium is formulated as follows:

[1024]

[1025]

[1026]

[1027] Mixture Example S32 (stabilized with the compound of formula ST-1-3)

[1028] A nematic LC mixture according to the present invention is formulated as follows:

[1029] Mixture M32 99.95 wt.-% Compound of formula ST-1-3 500 ppm

[1030] Compared with the non-stabilized mixture M32, adding 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M32.

[1031] Example M33

[1032] A nematic liquid crystal medium is formulated as follows:

[1033]

[1034]

[1035]

[1036] Mixture Example S33 (stabilized with the compound of formula ST-1-3)

[1037] A nematic LC mixture according to the present invention is formulated as follows:

[1038] Mixture M33 99.95 wt.-% Formula ST-1-3 500 ppm

[1039] Compared with the non-stabilized mixture M33, adding 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100, without affecting the remaining physical properties of the mixture M33.

[1040] Example M34

[1041] A nematic liquid crystal medium is formulated as follows:

[1042]

[1043]

[1044]

[1045] Mixture Example S34 (stabilized with the compound of formula ST-1-3)

[1046] A nematic LC mixture according to the present invention is formulated as follows:

[1047] Mixture M34 99.95 wt.-% Compound of formula ST-1-3 500 ppm

[1048] Compared with the non-stabilized mixture M34, the addition of 500 ppm of the compound of formula ST-1-3 significantly improves the VHR after UV exposure 100 , without affecting the remaining physical properties of the mixture M34.

Claims

1. A liquid crystal medium, characterized in that It comprises one or more compounds of formula I and one or more compounds of formula M The substituents have the following meanings: express express A 0 , A 1 and A 2 each independently of one another represents phenylene-1,4-diyl, wherein in addition, one or two CH groups may be replaced by N and one or more H atoms may be substituted by halogen, CN, CH3, CHF2, CH2F, CF3, OCH3, OCHF2 or OCF3; cyclohexane-1,4-diyl, wherein in addition, one or two non-adjacent CH2 groups may be substituted independently of one another by O and / or S and one or more H atoms may be substituted by F; cyclohexene-1,4-diyl; bicyclo[1.1.1]pentane-1,3-diyl; bicyclo[2.2.2]octane-1,4-diyl; spiro[3.3]heptane-2,6-diyl; tetrahydropyran-2,5-diyl; 1,3-dioxane-2,5-diyl; R 1 , R 2 and R 3 Each independently of one another is an H atom, a halogen atom, an alkyl or alkoxy group having 1 to 12 C atoms, or an alkenyl or alkenyloxy group having 2 to 12 C atoms, wherein one or more non-adjacent CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- substituted in such a way that the O atoms are not directly connected to one another and in which one or more H atoms may be substituted by halogen atoms, or cycloalkyl or cycloalkoxy having 3 to 12 C atoms, in which one or more H atoms may be substituted by halogen atoms; Y 0 is an H atom, an alkyl group having 1 to 3 C atoms or an alkenyl group having 2 to 3 C atoms, wherein one or more non-adjacent CH2 groups are optionally substituted by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other; W represents =N-, =(CH)- or =(CF)-; X 0 represents a halogen atom, CN, SCN, NCS, an alkyl or alkoxy group having 1 to 3 C atoms, in which one or more H atoms are substituted by halogen atoms, or an alkenyl or alkenyloxy group having 2 or 3 C atoms, in which one or more H atoms are substituted by halogen atoms; Z 1 , Z 2 , Z 3 and Z 4 Each independently represents -CF2O-, -OCF2, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2H4-, -C2F4-, -CF2CH2-, -CH2CF2-, -CFHCFH-, -CFHCH2-, -CH2CFH-, -CF2CFH-, -CFHCF2-, -CH=CH-, -CF=CH-, -CH=CF-, -CF=CF-, -C≡C- or a single bond; L 1-4 Each independently represents H or F; Y 1 and Y 2 each independently of one another represents H or a straight-chain or branched alkyl or alkoxy group having 1 to 6 C atoms, or a cycloalkyl or cycloalkoxy group having 3 to 6 C atoms; k and l each independently represent 0, 1, 2 or 3; and m and n each independently represent 0, 1 or 2, wherein (m+n)≧1.

2. The medium according to claim 1, characterized in that The compound of formula I is selected from the following compounds: in R 1 and R 2 As defined in claim 1; Y 0 and Y 3 each independently represents an H atom or a methyl group, preferably an H atom; and L 1 To L 6 Each independently of one another represents an H atom, F, Cl or an alkyl group having 1 to 4 C atoms.

3. The medium according to claim 1 or 2, characterized in that The one or more compounds of formula M are selected from the following compounds: in R 3 represents an alkyl or alkoxy group having 1 to 6 C atoms or an alkenyl group having 2 to 6 C atoms, wherein one or more CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- is substituted in such a way that the O atoms are not directly bonded to each other, and wherein one or more H atoms may be substituted by a halogen atom; L 1-4 Each independently represents H or F; Y 1 and Y 2 each independently of one another represents an H atom or a methyl group, preferably an H atom; and X 0 represents CN, SCN, NCS or an alkyl group having 1 to 6 C atoms, in which one or more H atoms are substituted by halogen atoms.

4. A medium according to one or more of claims 1 to 3, characterized in that The one or more compounds of formula M are selected from the following compounds: in R 3 represents an alkyl or alkoxy group having 1 to 6 C atoms or an alkenyl group having 2 to 6 C atoms, wherein one or more CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- is substituted in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be substituted by a halogen atom, and X 0 represents CN, SCN, NCS or an alkyl group having 1 to 6 C atoms, in which one or more H atoms are substituted by halogen atoms.

5. A medium according to one or more of claims 1 to 4, characterised in that It further comprises one or more compounds selected from the group consisting of formula LP1 and LP2 The substituents have the following meanings: R 0 The invention has the following characteristics: 1 One of the meanings given; R 2 represents an alkyl or alkoxy group having 1 to 12 C atoms or an alkenyl or alkenyloxy group having 2 to 12 C atoms, wherein one or more non-adjacent CH2 groups are optionally replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- is substituted in such a way that the O atoms are not directly connected to one another, and wherein one or more H atoms may be substituted by a cycloalkyl or cycloalkoxy group having 3 to 12 C atoms; X 0 represents a halogen atom, CN, SCN, NCS or an alkyl or alkoxy group having 1 to 6 C atoms, or an alkenyl or alkenyloxy group having 2 to 6 C atoms, wherein one or more H atoms are replaced by a halogen atom; L 1 and L 2 each independently represents H, F or Cl; and Y 0 represents H or CH3; and m and n each independently represent 0 or 1.

6. A medium according to one or more of claims 1 to 5, characterized in that It comprises one or more compounds selected from the following formula The substituents have the following meanings: R 0 The invention has the following characteristics: 1 One of the meanings given; X 0 With respect to X in claim 1 0 One of the meanings given; L 1 To L 6 Each independently represents H, F or Cl; Y 0 Each independently represents H or CH3.

7. The medium according to claim 6, wherein the one or more compounds of formula II are selected from the following subformulae: Where R 0 and X 0 has the meaning given in formula II.

8. The medium according to claim 6, wherein the one or more compounds of formula III are selected from the following subformulae: Where R 0 and X 0 has the meaning given in formula III.

9. A medium according to one or more of claims 1 to 8, characterized in that It additionally comprises one or more compounds selected from the following formulae Where R 0 , X 0 , L 1 , L 2 and Y 0 has the meaning given in claim 5; L 3 and L 4 Each independently has a 1 the meaning given; Z 0 represents -C2H4-, -(CH2)4-, -CH=CH-, -CF=CF-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH2O-, -OCH2-, -COO-, -CF2O- or -OCF2-, in Formulas V and VI, is also a single bond; and s represents 0 or 1.

10. The medium according to one or more of claims 1 to 9, characterized in that It contains one or more compounds selected from the following formulae: The substituents have the following meanings: "alkyl" and "alkyl" * " each independently of one another represents an alkyl group having 1 to 6 C atoms; "alkenyl" and "alkenyl * " each independently of one another represents an alkenyl group having 2 to 6 C atoms.

11. The medium according to one or more of claims 1 to 10, characterized in that It contains one or more compounds selected from the following formulae: in R 1 and R 2 each independently of one another represents an alkyl, alkoxy, oxaalkyl or fluoroalkyl group each having 1 to 6 C atoms, or an alkenyl group having 2 to 6 C atoms; and L 1 Has the meaning indicated in claim 1.

12. The medium according to one or more of claims 1 to 11, characterized in that It contains one or more compounds selected from the following formulae: Where R 0 , X 0 , Y 0 and L 1-4 Each has, independently of one another, one of the meanings indicated in claim 6.

13. The medium according to one or more of claims 1 to 12, characterized in that It contains one or more compounds selected from the following formulae: in R 1 and X 0 The invention has the following characteristics: 0 and X 0 The meaning shown.

14. A medium according to one or more of claims 1 to 13, characterized in that It comprises a compound of formula I, M and one or more compounds selected from formula L1, L2, Z1, Z2, Z3, Z4, Z5, II, III, IV, V, VI, VII, VIII, XIV, XVI, XX, XXIII, XXIX, XVIIa, XVIIb, XVIIc, XXXII and XXXIV.

15. The medium according to one or more of claims 1 to 14, characterized in that It additionally comprises one or more additives selected from dyes, antioxidants, stabilizers, dopants, SA-VA additives and polymerizable compounds.

16. Process for preparing a liquid-crystalline medium according to one or more of claims 1 to 14, characterized in that One or more compounds of the formula I and one or more compounds of the formula M are mixed with one or more mesogenic compounds and optionally one or more additives.

17. Use of a liquid-crystalline medium according to one or more of claims 1 to 15 for electro-optical purposes.

18. Electro-optical liquid crystal display or AR / VR headset or display comprising a liquid crystal medium according to one or more of claims 1 to 15.

19. The electro-optical liquid crystal display according to claim 18, characterized in that: It is a TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-HB-FFS, PS-XB-FFS, SA-HB-FFS, SA-XB-FS, polymer-stabilized SA-HB-FFS, polymer-stabilized SA-XB-FFS, positive VA or positive PS-VA display.

20. The electro-optical liquid crystal display according to claim 18, characterized in that: It is a FFS, HB-FFS, XB-FFS, PS-HB-FFS, PS-XB-FFS, IPS or PS-IPS display.

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