Liquid crystal medium

Abstract

The present invention relates to liquid crystal (LC) media with positive dielectric anisotropy and liquid crystal displays (LCDs) comprising these media, in particular to displays addressed by an active matrix, and in particular LC displays of the 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.

Description

Field of the Invention

[0001] The present invention relates to liquid crystal (LC) dielectrics having positive dielectric anisotropy and liquid crystal displays (LCDs) comprising these dielectrics, in particular to displays addressed by active matrix, and in particular to TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, PS-HB-FFS, SA-HB-FFS, polymer-stabilized SA-HB-FFS, positive VA or positive PS-VA type LC displays. Background of the Invention

[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-optical 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 liquid crystal layer.

[0003] In addition to these modes, there are also electro-optical modes that utilize an electric field substantially parallel to the substrate or the liquid crystal layer. For example, WO91 / 10936 discloses a liquid crystal display in which an electrical signal is generated in such a way that the electric field has an effective component parallel to the liquid crystal layer, and which has since become 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, Vol. 45, No. 12, pp. 5466-5468 (1974).

[0004] An IPS display comprises a liquid crystal layer between two substrates having a planar alignment, where two electrodes are arranged on only one of the two substrates and preferably have an interdigital comb structure. When a voltage is applied to the electrodes, an electric field having 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. This results in a strong so-called "fringe field", i.e., a strong electric field near the electrode edges, and an electric field having both a strong vertical component and a strong horizontal component throughout the cell. FFS displays have a low contrast viewing angle dependence. FFS displays typically include a liquid crystal medium having a positive dielectric anisotropy and an alignment layer, typically 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, and also for mobile phones, notebook PCs, etc. The liquid crystal medium according to the present invention is preferably used for this type of display. Generally, dielectric positive liquid crystal media having a rather low dielectric anisotropy value are used in FFS displays, but in some cases, liquid crystal media having a dielectric anisotropy of only about 3 or even less are also used in IPS displays.

[0009] Further improvements have been achieved by the so-called 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] Liquid crystal compositions suitable for LCDs, especially FFS and IPS displays, are known in the prior art, for example, they can be learned from JP07-181 439(A), EP 0 667 555, EP 0 673986, DE 195 09 410, DE 195 28 106, DE 19528 107, WO 96 / 23 851, and WO 96 / 28 521. 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. Here, it is necessary to improve not only the operating performance but also the storage life.

[0011] 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, individual pixels are typically addressed by integrated, non-linear active elements, such as thin film transistors (TFTs), while in the case of a passive matrix display, individual pixels are typically addressed by multiplexing methods known in the prior art.

[0012] Preferably, the display according to the invention is addressed by active matrix, preferably by a TFT matrix. However, the liquid crystals according to the invention can also be advantageously used in displays with other known addressing methods.

[0013] 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.

[0014] 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. The contrast ratio can be improved by higher transmittance in the bright state and better dark state. One solution to improve the dark state is to reduce the scattering parameter of the LC mixture by developing a mixture with a higher average elastic constant (K av ), but this usually has the disadvantage of reduced response time.

[0015] It has been observed that high brightness in displays such as those in the HB-FFS mode can be achieved by using a liquid crystal medium having positive dielectric anisotropy and also having an increased dielectric constant ε ⊥ perpendicular to the longitudinal axis of the liquid crystal molecules. This can be achieved by adding a limited amount of a liquid crystal compound having negative dielectric anisotropy and high ε ⊥ performance to the liquid crystal medium while maintaining the positive dielectric anisotropy of the entire medium. However, adding a compound with high ε ⊥ has some disadvantages. For example, this can result in higher values of the rotational viscosity γ1 and thus lead to a higher value of the ratio γ1 / K 22 for the rotational viscosity and the elastic constant K 22 for the twist deformation, which results in a higher response time. Since K 22 is approximately proportional to the elastic constant K 11 for the splay deformation (the value of K 22 is usually about half of the value of K 11 ), this can be easily determined by measuring γ1 and K 11 .

[0016] Another disadvantage is that the reliability (VHR) of the HB-FFS mixture may be worse compared to the conventional FFS mixture.

[0017] Maintaining good low-temperature stability (LTS) of the medium is also important. Especially for automotive navigation systems, good LTS is required, even at -40 °C. Due to this requirement, further improving the optical performance is challenging.

[0018] The object of the present invention is to provide a liquid crystal medium, preferably for FFS and IPS displays, in particular for HB-FFS displays, but also for TN, positive VA or STN displays, and in particular for active matrix displays, such as those addressed by TFTs, which do not exhibit the above-mentioned disadvantages or only exhibit them to a lesser extent, and in particular to provide a medium which enables the display to have an improved contrast and preferably does not deteriorate other display parameters.

[0019] To solve this problem, the present invention provides a liquid crystal medium according to claim 1.

[0020] Advantageous embodiments of the invention are the subject of the dependent claims or can also be obtained from the description. Summary of the Invention

[0021] The present invention relates to a liquid crystal medium preferably having a positive dielectric anisotropy, which comprises

[0022] a) one or more compounds of formula I

[0023]

[0024] wherein

[0025] R 11 and R 12 independently of one another represent H, a straight-chain alkyl or alkoxy group having 1-15 C atoms, a straight-chain alkenyl or alkenoxy group having 2-15 C atoms or a branched alkyl, alkoxy, alkenyl or alkenoxy group each having 3-15 C atoms, where one or more CH2 groups in these groups can each be independently replaced by -CH=CH-, -C≡C-, -CF2O-, -OCF2-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to one another, and where one or more H atoms can be replaced by halogen, L 11 and L 12 independently represent H, F, Cl, CH3, CF3 or CHF2;

[0026] preferably H or F, very preferably H;

[0027] and

[0028] b) one or more compounds selected from the compounds of formulae II and III

[0029]

[0030]

[0031] wherein

[0032] R 2 and R 3 has the meaning given above for R 11 and preferably represents an alkyl group having 1 - 7 C atoms or an alkenyl group having 2 - 7 C atoms,

[0033] each independently represents

[0034] L 21 、L 22 、L 31 and L 32 each independently represents H or F,

[0035] Y 2 and Y 3 are the same or different and represent H or CH3, preferably H,

[0036] X 2 and X 3 each independently represents a halogen, a haloalkyl or haloalkoxy group having 1 - 3 C atoms, or a haloalkenyl or haloalkenyloxy group having 2 or 3 C atoms, preferably F, Cl, CF3, OCF3 or OCHF2, more preferably F or OCF3,

[0037] Z 3 represents -CH2CH2-, -CF2CF2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CH2O- or a single bond, preferably a single bond, and

[0038] l, m, n and o are each independently 0 or 1.

[0039] The combination of the compound of formula I with the compound of formula II and / or III causes the liquid crystal medium to exhibit low rotational viscosity and low γ1 / K 22 and γ1 / K 11 ratio. This enables liquid crystal displays, in particular those of the HB-FFS, FFS and IPS modes, to have high brightness, high transmittance and fast response times. Furthermore, a higher average elastic constant (K av ) can be achieved while maintaining all other relevant physical properties, which results in a lower scattering parameter for the improved dark state of the display, thus improving the contrast.

[0040] In particular, the low temperature stability (LTS) of the medium according to the invention is very high. The medium is stable enough at temperatures as low as -40 °C, which is why the medium is particularly suitable for mobile applications, such as automotive applications.

[0041] The liquid crystal medium according to the invention is suitable for mobile applications and TFT applications, such as mobile phones and PDAs. In addition, the liquid crystal medium according to the invention is particularly suitable for FFS, HB-FFS and IPS displays based on dielectrically positive liquid crystals.

[0042] The liquid crystal medium according to the invention is also suitable for liquid crystal displays in FFS, HB-FFS and IPS modes based on dielectrically positive liquid crystals and their polymer-stabilized variants for large-size TV applications.

[0043] The invention also relates to the use of the liquid crystal medium as described in the context for electro-optical purposes, in particular for liquid crystal displays, shutter glasses, LC windows, 3D applications, preferably for TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, PS-HB-FFS, SA-HB-FFS, polymer-stabilized SA-HB-FFS, positive VA and positive PS-VA displays, very preferably for FFS, HB-FFS, IPS, PS-HB-FFS and PS-IPS displays.

[0044] The invention also relates to electro-optical liquid crystal displays comprising the liquid crystal medium as described in the context, in particular TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, PS-HB-FFS, SA-HB-FFS, polymer-stabilized SA-HB-FFS, positive VA or positive PS-VA displays, preferably FFS, HB-FFS, IPS, PS-HB-FFS or PS-IPS displays.

[0045] The invention also relates to compounds of formula I

[0046]

[0047] wherein

[0048] R 11 and R 12 independently of one another represent H, a straight-chain alkyl or alkoxy group having 1-15 C atoms, a straight-chain alkenyl or alkenoxy group having 2-15 C atoms or a branched alkyl, alkoxy, alkenyl, alkenoxy group each having 3-15 C atoms, where one or more CH2 groups in these groups may each independently of one another be -CH=CH-, -C≡C-, -CF2O-, -OCF2-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to one another, and where one or more H atoms may be replaced by halogen,

[0049] L11 and L 12 represents H, F, Cl, CH3, CF3 or CHF2, where L 11 and L 12 do not both represent H, and if L 11 and L 12 one of them represents F then L 11 and L 12 the other one is not Cl.

[0050] According to another aspect of the present invention, there is provided a compound of formula (3) as defined in Scheme 1 below.

[0051] The compound of formula I can be synthesized analogously to the synthesis of structurally related chlorofluoro derivatives shown in EP 1 897 928 A1.

[0052] The preferred synthetic route of the compound of formula I is shown in Scheme 1.

[0053] Scheme 1:

[0054]

[0055] where X represents Br or I, and the other groups shown have the above meanings.

[0056] As used herein, alkyl and / or alkoxy refer to straight-chain, branched-chain or cyclic alkyl. It is preferably straight-chain, having 2, 3, 4, 5, 6 or 7 C atoms, and thus preferably represents ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy. In addition, methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy or tetradecyloxy are also preferred.

[0057] As used herein, branched-chain alkyl is preferably isopropyl, s-butyl, isobutyl, isopentyl, 2-methylbutyl, 2-methylhexyl or 2-ethylhexyl.

[0058] As used herein, cycloalkyl refers to straight-chain or branched-chain alkyl or alkenyl having up to 12 C atoms, preferably alkyl having 1-7 C atoms, where the group CH2 is replaced by a carbocyclic ring having 3-5 C atoms, and is very preferably selected from cyclopropylalkyl, cyclobutylalkyl, cyclopentylalkyl and cyclopentenylalkyl, where the alkyl is a straight-chain alkyl having 1-5 C atoms.

[0059] In the present context, the oxaalkyl group preferably represents a straight-chain 2-oxapropyl ( = methoxymethyl), 2-oxabutyl ( = ethoxymethyl) or 3-oxabutyl ( = 2-methoxyethyl), 2-oxapentyl, 3-oxapentyl or 4-oxapentyl, 2-oxahexyl, 3-oxahexyl, 4-oxahexyl or 5-oxahexyl, 2-oxaheptyl, 3-oxaheptyl, 4-oxaheptyl, 5-oxaheptyl or 6-oxaheptyl, 2-oxaoctyl, 3-oxaoctyl, 4-oxaoctyl, 5-oxaoctyl, 6-oxaoctyl or 7-oxaoctyl, 2-oxanonyl, 3-oxanonyl, 4-oxanonyl, 5-oxanonyl, 6-oxanonyl, 7-oxanonyl or 8-oxanonyl, 2-oxadecyl, 3-oxadecyl, 4-oxadecyl, 5-oxadecyl, 6-oxadecyl, 7-oxadecyl, 8-oxadecyl or 9-oxadecyl.

[0060] In the present context, the alkenyl group, i.e. the alkyl group in which one CH2 group has been replaced by -CH = CH-, can be straight-chain or branched. It is preferably straight-chain and has 2 to 10 C atoms. Thus, it especially represents vinyl, prop-1-enyl or prop-2-enyl, but-1-enyl, but-2-enyl or but-3-enyl, pent-1-enyl, pent-2-enyl, pent-3-enyl or pent-4-enyl, hex-1-enyl, hex-2-enyl, hex-3-enyl, hex-4-enyl or hex-5-enyl, hept-1-enyl, hept-2-enyl, hept-3-enyl, hept-4-enyl, hept-5-enyl or hept-6-enyl, oct-1-enyl, oct-2-enyl, oct-3-enyl, oct-4-enyl, oct-5-enyl, oct-6-enyl or oct-7-enyl, non-1-enyl, non-2-enyl, non-3-enyl, non-4-enyl, non-5-enyl, non-6-enyl, non-7-enyl or non-8-enyl, dec-1-enyl, dec-2-enyl, dec-3-enyl, dec-4-enyl, dec-5-enyl, dec-6-enyl, dec-7-enyl, dec-8-enyl or dec-9-enyl.

[0061] In the present context, the alkyl or alkenyl group monosubstituted at least by a halogen 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 at any desired position, but preferably at the ω-position.

[0062] In the present text, monofluoro- or polyfluoroalkyl or alkoxy groups having 1, 2 or 3 C atoms, or monofluoro- or polyfluoroalkenyl groups having 2 or 3 C atoms, are particularly preferably F, Cl, CF3, CHF2, OCF3, OCHF2, OCFHCF3, OCFHCHF2, OCFHCHF2, OCF2CH3, OCF2CHF2, OCF2CHF2, OCF2CF2CHF2, OCF2CF2CHF2, OCFHCF2CF3, OCFHCF2CHF2, OCF2CF2CF3, OCF2CF2CClF2, OCClFCF2CF3, OCH=CF2 or CH=CF2, very particularly preferably F or OCF3, and CF3, OCF=CF2, OCHF2 or OCH=CF2.

[0063] The compounds of formula I are preferably selected from the compounds of formulae I-1 to I-4

[0064]

[0065] wherein R 11 and R 12 have the meanings defined above for formula I and preferably represent straight-chain alkyl or alkoxy groups each having 1 - 7 C atoms, or straight-chain alkenyl groups having 2 - 15 C atoms, where one or more CH2 groups in these groups may each independently of one another be replaced, and very preferably represent straight-chain alkyl groups having 1 - 7 C atoms or straight-chain alkenyl groups having 1 - 7 C atoms.

[0066] More preferably, the medium according to the invention comprises one or more compounds of formula I-1, very preferably selected from the compounds of formulae I-1-1 to I-1-32

[0067]

[0068]

[0069]

[0070]

[0071]

[0072] wherein R 11 and R 12 represent straight-chain alkyl groups having 1 - 7 C atoms or straight-chain alkenyl groups having 2 - 7 C atoms.

[0073] The compounds of formula I-2 are preferably selected from the compounds of formulae I-2-1 to I-2-32:

[0074]

[0075]

[0076]

[0077]

[0078]

[0079] The compound of formula I-3 is preferably selected from the compounds of formula I-3-1 to I-3-32:

[0080]

[0081]

[0082]

[0083]

[0084]

[0085] The compound of formula I-4 is preferably selected from the compounds of formula I-4-1 to I-4-32:

[0086]

[0087]

[0088]

[0089]

[0090]

[0091] Preferably, the medium comprises one or more compounds of formula II, preferably selected from the compounds of formula II-1 to II-3, and very preferably selected from the compounds of formula II-1 and II-3

[0092]

[0093] wherein the groups occurring have the corresponding meanings given under formula II above, and in formula II-1, the group L 23 and L 24 each independently represent H or F, and in formula II-2 preferably each independently represent

[0094]

[0095] In Formulas II-1, II-2 and II-3, L 21 and L 22 or L 23 and L 24 are preferably all F.

[0096] In another preferred embodiment, in Formulas II-1 and II-2, L 21 , L 22 , L 23 and L 24 all represent F.

[0097] The compound of Formula II-1 is preferably selected from the compounds of Formula II-1a to II-1h

[0098]

[0099]

[0100] wherein the groups appearing have the corresponding meanings given above.

[0101] In a preferred embodiment of the present invention, the medium comprises one or more compounds selected from the compounds of Formula II-1a to II-1h, wherein L 21 and L 22 , and / or L 23 and L 24 are each F.

[0102] In another preferred embodiment, the medium comprises a compound selected from the compounds of Formula II-1a to II-1h, wherein L 21 , L 22 , L 23 and L 24 are all F.

[0103] Particularly preferred compounds of Formula II-1 are

[0104]

[0105] wherein R 2 has the meaning given above.

[0106] Preferably, the compound of Formula II-2 is selected from the compounds of Formula II-2a to II-2c

[0107]

[0108]

[0109] wherein the groups appearing have the corresponding meanings given above, and preferably L 21 and L 22 are both F.

[0110] Preferably, the compound of formula II-3 is selected from the compounds of formula II-3a to II-3e

[0111]

[0112]

[0113] wherein the groups appearing have the corresponding meanings given above, and preferably L 21 and L 22 are both F and L 23 and L 24 are both H, or

[0114] L 21 、L 22 、L 23 and L 24 are all F.

[0115] Particularly preferred compounds of formula II-3 are

[0116]

[0117] wherein R 2 has the meaning given above.

[0118] In addition to the above preferred compounds of formula II, the medium optionally further comprises one or more compounds of formula II selected from the compounds of formula IIA1 to IIA7:

[0119]

[0120]

[0121] wherein R 2 and X 2 have the meanings given in formula II or one of the preferred meanings given in the context.

[0122] Preferred compounds are the compounds of formula IIA1, IIA2 and IIA3, and very preferably the compounds of formula IIA1 and IIA2.

[0123] In the compounds of formula IIA1 to IIA7, R 2 preferably represents an alkyl group having 1 to 6 C atoms, very preferably ethyl or n-propyl, and X 2 preferably represents F or OCF3, very preferably F.

[0124] In another preferred embodiment of the present invention, the medium comprises one or more compounds of formula III preferably selected from formula III-1 and III-2, preferably formula III-2:

[0125]

[0126] The groups and parameters appearing therein have the corresponding meanings given above under formula III.

[0127] R 3 Preferably represents an alkyl group having 1 - 7 C atoms or an alkenyl group having 2 - 7 C atoms.

[0128] Preferably, the compounds of formula III - 1 are selected from the compounds of formula III - 1a and III - 1b

[0129]

[0130]

[0131] The groups appearing therein have the corresponding meanings given above, and L 33 and L 34 each independently represents H or F.

[0132] The compounds of formula III - 1a are preferably selected from the compounds of formula III - 1a - 1 to III - 1a - 6

[0133]

[0134] wherein R 3 has the meaning given above.

[0135] Preferably, the compounds of formula III - 2 are selected from the compounds of formula III - 2a to III - 2m

[0136]

[0137]

[0138] wherein the groups appearing therein have the corresponding meanings given above, and L 35 and L 36 each independently represents H or F.

[0139] Preferably, the compounds of formula II - 2a are selected from the compounds of formula III - 2a - 1 to III - 2a - 4

[0140]

[0141]

[0142] wherein R 3 has the meaning given above.

[0143] The compounds of formula III - 2b are preferably selected from the compounds of formula III - 2b - 1 and III - 2b - 2, preferably III - 2b - 2

[0144]

[0145] wherein R 3 has the meaning given above.

[0146] The compounds of formula III-2c are preferably selected from the compounds of formula III-2c-1 to III-2c-5

[0147]

[0148]

[0149] wherein R 3 has the meaning given above.

[0150] The compounds of formula III-2d and III-2e are preferably selected from the compounds of formula III-2d-1 and III-2e-1

[0151]

[0152] wherein R 3 has the meaning given above.

[0153] The compounds of formula III-2f are preferably selected from the compounds of formula III-2f-1 to III-2f-7

[0154]

[0155]

[0156] wherein R 3 has the meaning given above.

[0157] The compounds of formula III-2g are preferably selected from the compounds of formula III-2g-1 to III-2g-7

[0158]

[0159]

[0160] wherein R 3 has the meaning given above.

[0161] The compounds of formula III-2h are preferably selected from the compounds of formula III-2h-1 to III-2h-5

[0162]

[0163]

[0164] wherein R 3has the meaning given above.

[0165] The compound of formula III-2i is preferably selected from the compounds of formulae III-2i-1 to III-2i-3

[0166]

[0167] wherein R 3 has the meaning given above.

[0168] The compound of formula III-2j is preferably selected from the compounds of formulae III-2j-1 to III-2j-3

[0169]

[0170]

[0171] wherein R 3 has the meaning given above.

[0172] The compound of formula III-2k is preferably selected from the compounds of formulae III-2k-1 to III-2k-6

[0173]

[0174]

[0175] wherein R 3 has the meaning given above.

[0176] The compound of formula III-2l is preferably selected from the compounds of formulae III-2l-1 to III-2l-6

[0177]

[0178]

[0179] wherein R 3 has the meaning given above.

[0180] The compound of formula III-2m is preferably selected from the compound of formula III-2m-1

[0181]

[0182] Alternatively, or in addition to the compounds of formulae III-1 and / or III-2, the medium according to the invention optionally further comprises one or more compounds of formula III-3,

[0183]

[0184] wherein the groups and parameters have the respective meanings given above under formula III,

[0185] Preferred formula III-3a

[0186]

[0187] wherein R 3 has the meaning given above.

[0188] In addition to the above preferred formula III compounds, the medium optionally further comprises one or more compounds selected from formulae IIIA-1 to IIIA-21:

[0189]

[0190]

[0191]

[0192]

[0193] wherein R 3 and X 3 have the meanings given in formula III or one of the preferred meanings given in the context. Preferred compounds are formula IIIA1, IIIA4, IIIA6, IIIA16, IIIA19 and IIIA20 compounds.

[0194] In the compounds of formulae IIIA-1 to IIIA-21, R 3 preferably represents an alkyl group having 1-6 C atoms, very preferably ethyl or propyl, and X 3 preferably represents F or OCF3, very preferably F.

[0195] Preferably, the medium according to the present invention comprises one or more compounds of formula IV

[0196]

[0197] wherein

[0198] R 11 represents a straight-chain alkyl group having 1-12 C atoms or a branched or cyclic alkyl group having 3-12 C atoms, or a straight-chain alkenyl group having 2-12 C atoms or a branched alkenyl group having 3-12 C atoms or a cyclic alkenyl group having 5-12 C atoms, wherein one or more H atoms are optionally replaced by fluorine, preferably a straight-chain alkyl group having 1-12 C atoms, very preferably a straight-chain alkyl group having 1-7 C atoms,

[0199] R 12represents a straight-chain alkyl or alkoxy group having 1 to 12 carbon atoms or a branched or cyclic alkyl or alkoxy group having 3 to 12 carbon atoms, or a straight-chain alkenyl group having 2 to 12 carbon atoms or a branched alkenyl group having 3 to 12 carbon atoms or a cyclic alkenyl group having 5 to 12 carbon atoms, wherein one or more H atoms are optionally replaced by fluorine, preferably a straight-chain alkenyl group having 2 to 12 carbon atoms, very preferably a straight-chain alkenyl group having 2 to 7 carbon atoms.

[0200] The compound of formula IV is preferably selected from the compounds of formulae IV-1 to IV-4, very preferably formula IV-3

[0201]

[0202] wherein

[0203] alkyl and alkyl’ each independently represent an alkyl group having 1 to 7 carbon atoms, preferably having 2 to 5 carbon atoms,

[0204] alkoxy represents an alkoxy group having 1 to 5 carbon atoms, preferably having 2 to 4 carbon atoms,

[0205] alkenyl represents an alkenyl group having 2 to 5 carbon atoms, preferably having 2 to 4 carbon atoms, particularly preferably 2 carbon atoms, and

[0206] alkenyl’ represents an alkenyl group having 2 to 5 carbon atoms, preferably having 2 to 4 carbon atoms, particularly preferably having 2 to 3 carbon atoms.

[0207] Preferably, the medium comprises one or more compounds of formula IV-1, preferably selected from the compounds of formulae IV-1-1 to IV-1-6

[0208]

[0209] Preferably, the medium according to the invention comprises one or more compounds of formula IV-2-1 and / or IV-2-2

[0210]

[0211] Preferably, the medium according to the invention comprises a compound of formula IV-3, very preferably selected from the compounds of formulae IV-3-1 to IV-3-6, especially the compounds of formula IV-3-2 and / or IV-3-6:

[0212]

[0213] Preferably, the medium according to the invention comprises a compound of formula IV-4, especially selected from the compounds of formulae IV-4-1 and IV-4-2:

[0214]

[0215] Preferably, the medium according to the invention comprises one or more compounds of formula IVa and / or IVb, very preferably IVb

[0216]

[0217]

[0218] wherein

[0219] R 41 and R 42 each independently of one another represent a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkenyloxy having up to 12 C atoms, and

[0220] represents

[0221] Z 4 represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -C4H8- or -CF=CF-.

[0222] Preferred compounds of formula IVa are selected from compounds of formulae IVa-1 to IVa-4:

[0223]

[0224] wherein

[0225] alkyl and alkyl * each independently of one another represent a straight-chain alkyl having 1-6 C atoms.

[0226] The medium according to the invention preferably comprises at least one compound of formula IVa-2.

[0227] Preferred compounds of formula IVb are selected from compounds of formulae IVb-1 to IVb-3:

[0228]

[0229]

[0230] wherein

[0231] alkyl and alkyl * each independently of one another represent a straight-chain alkyl having 1-6 C atoms, and

[0232] alkenyl and alkenyl* Each independently represents a linear alkenyl group having 2 to 6 carbon atoms.

[0233] Among the compounds of Formulae IVb-1 to IVb-3, the compound of Formula IVb-2 is particularly preferred.

[0234] Highly particularly preferred compounds of Formula IVb are selected from the following compounds:

[0235]

[0236] The medium according to the invention particularly preferably comprises the compound IVb-2-3.

[0237] In a preferred embodiment, the medium according to the invention comprises one or more compounds of Formula V

[0238]

[0239] wherein

[0240] R 51 、R 52 represent an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms or an alkoxyalkyl, alkenyl or alkenyloxy group having 2 to 7 carbon atoms,

[0241] are the same or different and represent

[0242] Z 51 、Z 52 each independently represent -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, and

[0243] n is 1 or 2.

[0244] Excluded are compounds of Formula I and CL compounds.

[0245] Compounds of Formula V are preferably selected from compounds of Formulae V-1, V-2, V-3 and V-4:

[0246]

[0247] wherein the groups occurring have the meanings given above for Formula V.

[0248] Compounds of Formula V-1 are preferably selected from compounds of Formulae V-1-1 to V-1-8;

[0249] Compounds of Formula V-2 are preferably selected from compounds of Formulae V-2-1 to V-2-4; and

[0250] The compound of formula V-3 is preferably selected from the compounds of formula V-3-1 to V-3-4:

[0251]

[0252]

[0253]

[0254] wherein R 51 and R 52 have the meanings as defined above for formula V.

[0255] R 51 and R 52 each preferably independently of one another represent a straight-chain alkyl group having 1-7 C atoms or an alkenyl group having 2-7 C atoms.

[0256] The very preferred compound of formula V-2-1 is selected from the compounds of formula V-2-1a to V-2-1g

[0257]

[0258]

[0259] The very preferred compound of formula V-2-2 is selected from the compounds of formula V-2-2a to V-2-2i

[0260]

[0261]

[0262] Preferably, the medium according to the invention comprises one or more compounds of formula CL

[0263]

[0264] wherein

[0265] R L represents H, a straight-chain or branched-chain alkyl or alkoxy group having 1-15 C atoms, or a straight-chain or branched-chain alkenyl group having 2-15 C atoms, where one or more CH2 groups in these groups may each independently of one another be -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- substituted in such a way that the O atoms are not directly linked to one another, and wherein furthermore, one or more H atoms may be replaced by halogen,

[0266] X Lrepresents F, Cl, CN, CHF2, CF3, OCF3, or, identically or differently, has R L One of the meanings of

[0267] Y L represents H, F, Cl or CH3.

[0268] The CL compounds of the formula are preferably selected from the compounds of the formulae CL-1, CL-2 and CL-3:

[0269]

[0270] wherein

[0271] R L1 and R L2 , identically or differently, have the meanings given above for formula I, preferably represent alkyl or alkenyl having 1-7 C atoms or 2-7 C atoms respectively, where CH2 groups may be replaced by cyclopropane-1,2-diyl, and R L2 alternatively represents an alkoxy group having 1-5 C atoms.

[0272] The very preferred CL compounds of the formula are selected from the compounds of the formulae CL-3-1 to CL-3-12:

[0273]

[0274]

[0275] In a particularly preferred embodiment, the medium according to the invention comprises the compound CL-3-1 or CLP-3-3.

[0276] In a preferred embodiment of the invention, the medium additionally comprises one or more compounds of the formulae VI-1 to VI-9

[0277]

[0278]

[0279] wherein

[0280] R 6 each independently of one another has one of the meanings of R 1 shown in claim 1, and

[0281] w each independently of one another represents an integer from 1 to 6.

[0282] In a preferred embodiment of the invention, the medium additionally comprises one or more compounds of the formula VII,

[0283]

[0284] wherein

[0285] R 71 and R 72 represent H, F, a straight-chain alkyl or alkoxy group having 1 to 15 C atoms, a straight-chain alkenyl or alkenyloxy group having 2 to 15 C atoms, or a branched alkyl, alkoxy, alkenyl, or alkenyloxy group each having 3 to 15 C atoms, where one or more CH2 groups in these groups may each independently of one another be 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 halogen,

[0286] X 71 to X 76 are the same or different and represent H or F, preferably at least one of X 71 to X 76 represents F, more preferably at least two of X 71 to X 76 represent F;

[0287] Z 71 and Z 72 are the same or different and represent CH2CH2 or a single bond.

[0288] The compounds of formula VII are preferably selected from formulae VII-1 and VII-2:

[0289]

[0290] wherein the groups occurring therein have the meanings given for formula VII.

[0291] The compounds of formula VII-1 are preferably selected from the compounds of formulae VII-1-1 to VII-1-21, very preferably formula VII-1-4:

[0292]

[0293]

[0294]

[0295]

[0296] wherein R 7 represents a straight-chain alkyl or alkoxy group having 1 to 6 C atoms, (O) represents -O- or a single bond, and m is 0, 1, 2, 3, 4, 5, or 6, and n is 0, 1, 2, 3, or 4.

[0297] R 7 Preferably represent methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy.

[0298] In the compound of formula VII-1-4, (O) preferably represents -O-.

[0299] The compound of formula VII-2 is preferably selected from formula VII-2-1 to VII-2-15, and very preferably formula VII-2-1:

[0300]

[0301]

[0302]

[0303] wherein R 7 represents a straight-chain alkyl or alkoxy group having 1-6 C atoms, (O) represents -O- or a single bond, and m is 0, 1, 2, 3, 4, 5 or 6, and n is 0, 1, 2, 3 or 4.

[0304] R 7 Preferably represent methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy.

[0305] Preferably, the medium according to the present invention comprises one or more compounds of formula VIII:

[0306]

[0307] wherein

[0308] R 81 and R 82 independently of one another represent H, halogen, CN, SCN, a straight-chain alkyl or alkoxy group having 1-15 C atoms, a straight-chain alkenyl or alkenyloxy group having 2-15 C atoms or a branched-chain alkyl, alkoxy, alkenyl or alkenyloxy group having 3-15 C atoms, where one or more CH2 groups in these groups may each independently of one another be -C≡C-, -CF2O-, -OCF2-, -CH=CH-, replaced by -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly linked to one another, and where one or more H atoms may be replaced by halogen,

[0309] A 0 、A 81 and A 82Each independently of one another represents 1,4-phenylene in which 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 in which 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;

[0310] Z 81 and Z 82 Each independently of one another 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;

[0311] n represents 0, 1, 2 or 3, preferably 0, 1 or 2, very preferably 0 or 1, particularly preferably 0; and

[0312] m represents 0, 1, 2 or 3, preferably 0, 1 or 2, very preferably 1 or 2, especially 1.

[0313] wherein the compound of formula I is excluded from formula VIII.

[0314] A in formula I 81 and A 82 preferably represents 1,4-phenylene which may also be mono- or polysubstituted by F and may furthermore represent cyclohexane-1,4-diyl, 1,4-cyclohexenylene, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl, very preferably 1,4-phenylene which may also be mono- or polysubstituted by F, or cyclohexane-1,4-diyl.

[0315] Z in formula VIII 81 and Z 82 preferably represents -CF2O-, -OCF2- or a single bond, very preferably a single bond.

[0316] A in formula VIII 81 and A 82 particularly preferably represents

[0317] wherein L represents halogen, CF3 or CN, preferably F.

[0318] In addition, compounds of formula VIII are preferred, wherein R 81 and R 82 each independently of one another represent H, F, or an alkyl, alkoxy, alkenyl or alkynyl group having 1 - 8, preferably 1 - 5 C atoms, each of which is optionally substituted by halogen, in particular F.

[0319] R 81 and R 82 preferably represent H, an optionally fluorinated alkyl or alkoxy group having 1 - 7 C atoms, an optionally fluorinated alkenyl or alkynyl group having 2 - 7 C atoms, an optionally fluorinated cycloalkyl group having 3 - 12 C atoms.

[0320] Preferably, at least one of R 81 and R 82 is not H, particularly preferably neither R 81 nor R 82 is H. R 81 is very particularly preferably an alkyl group. R 82 is also preferably H, an alkyl group or fluorine. Very particularly preferably, R 81 is an alkyl group and R 82 is H or an alkyl group. R 81 and R 82 each independently of one another very particularly preferably represent an unbranched alkyl group having 1 - 5 C atoms. If R 81 and R 82 represent a substituted alkyl, alkoxy, alkenyl or alkynyl group, then the total number of C atoms in the two groups of R 81 and R 82 is preferably less than 10.

[0321] Preferred compounds of formula VIII are selected from the following sub - formulas, more preferably from compounds of formula VIII - 3:

[0322]

[0323] wherein R 81 and R 82 have the above meanings, L represents F, r, s and t are independently 0, 1, 2, 3 or 4. r is preferably 1 or 2, very preferably 2, s and t are independently preferably 0 or 1, very preferably 0. R 81 and R 82 each particularly independently represent an n - alkyl group having 1 - 5 C atoms.

[0324] In a first highly preferred embodiment, the compounds of formulae VIII-1 to VIII-6 are selected from the compounds of formulae VIII-1a to VIII-6a, especially the compound of formula VIII-3a:

[0325]

[0326] wherein R 81 、R 82 、L, r and s have the meanings defined above.

[0327] In a second highly preferred embodiment, the compounds of formulae VIII-1 to VIII-6 are selected from the compounds of formulae VIII-1b to VIII-5b, especially the compound of formula VIII-2b:

[0328]

[0329]

[0330] wherein R 1 、R 2 、R 81 、R 82 、L, r and s have the meanings defined above.

[0331] In a third highly preferred embodiment, the compounds of formulae VIII-1 to VIII-6 are selected from the compounds of formulae VIII-1c to VIII-6c, especially the compound of formula VIII-3c:

[0332]

[0333] wherein R 1 、R 2 、R 81 、R 82 、L, r and s have the meanings defined above.

[0334] In a fourth highly preferred embodiment, the compounds of formulae VIII-1 to VIII-6 are selected from the compounds of formulae VIII-1d to VIII-6d, especially the compound of formula VIII-3d:

[0335]

[0336] wherein R 1 、R 2 、R 81 、R 82 、L, r and s have the meanings defined above.

[0337] In a particularly preferred embodiment, the medium according to the invention comprises one or more compounds selected from compounds of formulae VIII-1a to VIII-6a and one or more compounds selected from compounds of formulae VIII-1b to VIII-6b.

[0338] Very particularly preferably, the medium comprises one or more compounds selected from compounds of formulae VIII-3a, VIII-2b, VIII-3c and VIII-3d:

[0339]

[0340]

[0341] wherein R 81 、R 82 、L and r have the meanings defined above, and preferably r is 0.

[0342] The most preferred compounds of formula VIII particularly include one or more of the following:

[0343]

[0344]

[0345]

[0346] Alternatively or additionally, the following compounds of formula VIII can be used:

[0347]

[0348]

[0349]

[0350] The medium according to the invention optionally comprises one or more compounds having negative dielectric anisotropy, preferably selected from formulae Y, B, BC, CR, PH-1 and PH-2:

[0351]

[0352]

[0353] wherein

[0354] R Y1 、R Y2 、R B1 、R B2 、R CR1 、R CR2 、R P1 and R P2each independently represents H, an alkyl or alkoxy group having 1 to 15 C atoms, where one or more CH2 groups in these groups may each independently be replaced by -CH=CH-, -C≡C-, -CF2O-, -OCF2-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not directly connected to each other, and where one or more H atoms may be replaced by halogen,

[0355] each independently represents, each time it appears,

[0356] a) 1,4 - cyclohexenylene or 1,4 - cyclohexylene, where one or two non - adjacent CH2 groups may be replaced by -O- or -S-,

[0357] b) 1,4 - phenylene, where one or two CH groups may be replaced by N, or

[0358] c) a group selected from spiro[3.3]heptane - 2,6 - diyl, 1,4 - bicyclo[2.2.2]octylene, naphthalene - 2,6 - diyl, decahydronaphthalene - 2,6 - diyl, 1,2,3,4 - tetrahydronaphthalene - 2,6 - diyl, phenanthrene - 2,7 - diyl and fluorene - 2,7 - diyl,

[0359] where the groups a), b) and c) may be mono - or polysubstituted by halogen atoms,

[0360] preferably

[0361] Z x 、Z y are the same or different and represent -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH - CH2O- or a single bond, preferably a single bond,

[0362] Z 1 each independently represents, each time it appears, -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH - CH2O-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond, preferably CH2O or a single bond, and

[0363] L 11 and L 12Each independently represents F, Cl, CF3 or CHF2, preferably H or F, most preferably F, and

[0364] W represents O or S,

[0365] n is 0, 1 or 2, preferably 0 or 1,

[0366] c is 0, 1 or 2, preferably 1 or 2,

[0367] x and y are independently 0, 1 or 2, where x + y ≤ 3.

[0368] The compound of formula Y is preferably selected from compounds of formula YA, YB, YC and YD:

[0369]

[0370]

[0371] wherein

[0372] R 2A 、R 2B 、R 2C and R 2D each independently represents H, an alkyl or alkenyl group having at most 15 C atoms, which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, wherein in addition, one or more CH2 groups in these groups may be replaced by -O-, -S-, -C≡C-, -CF2O-, -OCF2-, -OC-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, L 1 to L 4 each independently represents F, Cl, CF3 or CHF2,

[0373] Y represents H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, very preferably H,

[0374] Z 2 、Z 2B and Z 2D each independently represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF- or -CH=CHCH2O-,

[0375] (O) represents O or a single bond,

[0376] p is 0, 1 or 2,

[0377] q is 0 or 1, and

[0378] v represents 1, 2, 3, 4, 5 or 6.

[0379] The preferred compounds of formulae YA, YB, YC and YD are shown below:

[0380]

[0381]

[0382]

[0383]

[0384]

[0385]

[0386]

[0387]

[0388]

[0389]

[0390]

[0391]

[0392] wherein the parameter a represents 1 or 2, alkyl and alkyl * each independently of one another represent straight-chain alkyls having 1-6 C atoms, and alkenyl represents a straight-chain alkenyl having 2-6 C atoms, and (O) represents an oxygen atom or a single bond. Alkenyl preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0393] Particularly preferred mixtures according to the invention comprise one or more compounds of formulae YA-2, YA-8, YA-10, YA-16, YA18, YA-40, YA-41, YA-42, YA-43, YB-2, YB-10, YB-16, YC-1, YD-4 and YD-10.

[0394] The proportion of the compounds of formula YA and / or YB in the overall mixture is preferably at least 20% by weight.

[0395] The medium according to the invention preferably comprises at least one compound of formula YC-1,

[0396]

[0397] wherein alkyl and alkyl * have the above meanings and are preferably present in an amount of < 5% by weight, in particular > 3% by weight.

[0398] The compounds of formula B are preferably selected from the compounds of formula B-1 and / or B-2

[0399]

[0400] wherein the groups occurring have the same meanings as given under formula B above, and preferably

[0401] R 11 and R 12 are each independently of the other an alkyl, alkenyl or alkoxy group having at most 15 C atoms, more preferably one or both of them represent an alkoxy group, and

[0402] L 11 and L 12 each preferably represent F.

[0403] Preferably, the compounds of formula B-1 are selected from the compounds of formula B-1-1 to B-1-10, preferably the compound of formula B-1-6,

[0404]

[0405]

[0406] wherein

[0407] alkyl and alkyl * each independently of the other represent a straight-chain alkyl group having 1-6 C atoms, alkenyl and alkenyl * each independently of the other represent a straight-chain alkenyl group having 2-6 C atoms, alkoxy and alkoxy * each independently of the other represent a straight-chain alkoxy group having 1-6 C atoms, and L 11 and L 12 each independently of the other represent F or Cl, preferably both are F.

[0408] Preferably, the compounds of formula B-2 are selected from the compounds of formula B-2-1 to B-2-10, preferably the compound of formula B-2-6,

[0409]

[0410]

[0411]

[0412] wherein

[0413] alkyl and alkyl * each independently represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl and alkenyl * each independently represent a straight-chain alkenyl group having 2 to 6 C atoms, alkoxy and alkoxy * each independently represent a straight-chain alkoxy group having 1 to 6 C atoms, and L 11 and L 12 each independently represent F or Cl, preferably both are F.

[0414] Optionally, the medium contains one or more compounds of formula BA-1 and / or BA-2

[0415]

[0416] wherein L 11 and L 12 have the same meaning as given under formula B, (O) represents O or a single bond,

[0417] R IIIA represents an alkyl or alkenyl group having at most 7 C atoms, or the group Cy-C m H 2m -,

[0418] m and n are the same or different and are 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1,

[0419] Cy represents an alicyclic group having 3, 4 or 5 ring atoms, which is optionally substituted with an alkyl or alkenyl group each having at most 3 C atoms, or with a halogen or CN, and preferably represents cyclopropyl, cyclobutyl or cyclopentyl.

[0420] The compounds of formula BA-1 and / or BA-2 can be contained in the medium in place of or additionally to the compounds of formula B, preferably additionally.

[0421] Very preferred compounds of formula BA-1 and BA-2 are as follows:

[0422]

[0423]

[0424] wherein alkoxy represents a straight-chain alkoxy group having 1 to 6 C atoms, or alternatively represents –(CH2)n F, where n is 2, 3, 4 or 5, preferably C2H4F.

[0425] Alternatively, the medium comprises one or more compounds of formula BAa-1-3

[0426]

[0427] where alkenyl represents a straight-chain alkenyl having 2-6 C atoms, preferably 4 C atoms, very preferably CH3-CH=CH-CH2-.

[0428] In a preferred embodiment of the present invention, the medium comprises one or more compounds of formula B-3

[0429]

[0430] where

[0431] R 11 、R 12 are the same or different and represent H, an alkyl or alkoxy group having 1-15 C atoms, where one or more CH2 groups in these groups are optionally independently 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, additionally, one or more H atoms may be replaced by halogen.

[0432] The compounds of formula B-3 are preferably selected from the compounds of formula B-3-1 to B-3-10:

[0433]

[0434]

[0435] where R 12 represents an alkyl group having 1-7 C atoms, preferably ethyl, n-propyl or n-butyl, or alternatively represents cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl, or alternatively represents –(CH2) n F, where n is 2, 3, 4 or 5, preferably C2H4F.

[0436] In a preferred embodiment of the present invention, the medium comprises one or more compounds of formula B-4 to B-6, preferably formula B-5,

[0437]

[0438]

[0439] The groups occurring therein have the meanings given above, R 11 preferably represents a straight-chain alkyl group, R 12 preferably represents an optionally fluorinated alkoxy group, each having 1 - 7 C atoms.

[0440] In a preferred embodiment, the medium comprises one or more compounds of formula I selected from formulas B-7 to B-9, preferably a compound of formula B-8

[0441]

[0442] wherein the parameters have the meanings given above, R 11 preferably represents a straight-chain alkyl group, R 12 preferably represents F or an optionally fluorinated alkoxy group, each having 1 - 7 C atoms.

[0443] Particularly preferred compounds of formula BC, CR and PH-1 are compounds BC-1 to BC-7, CR-1 to CR-5 and BP-1 to BP-7

[0444]

[0445]

[0446]

[0447]

[0448] wherein

[0449] alkyl and alkyl * each independently of one another represents a straight-chain alkyl group having 1 - 6 C atoms, and

[0450] alkenyl and alkenyl * each independently of one another represents a straight-chain alkenyl group having 2 - 6 C atoms.

[0451] More preferably, it comprises a mixture of one, two or three of BC-2, BC-3, BP-2 and / or BP-3, very preferably BP-2 and / or BP-3, especially a compound of BP-3.

[0452] In a preferred embodiment, the medium according to the invention comprises one or more HALS stabilizers of formula H:

[0453]

[0454] wherein

[0455] Ar represents a methylene group, an aromatic hydrocarbon group having 6 to 40 C atoms, or a heteroaromatic hydrocarbon group having 4 to 40 C atoms; preferably an aromatic hydrocarbon group having 6 to 40 C atoms;

[0456] Sp represents a spacer group;

[0457] R S represents H, an alkyl group having 1 to 12 C atoms, or an alkenyl group having 2 to 12 C atoms;

[0458] Z S represents -O-, -C(O)O-, -(CH2) z -, or -(CH2) z O- or a single bond;

[0459] HA represents

[0460] R H represents H, O · , CH3, OH or OR S ;

[0461] R S1 , R S2 , R S3 and R S4 are the same or different and represent an alkyl group having 1 to 6 C atoms, preferably having 1 to 3 C atoms, very preferably CH3;

[0462] G represents H or R S or the group Z S -HA;

[0463] z is an integer from 1 to 6; and

[0464] q is 2, 3 or 4, preferably 3 or 4;

[0465] The compound of formula I is preferably selected from the compounds of formula H-1, H-2 and H-3:

[0466]

[0467]

[0468] wherein R H has the above meanings and preferably represents H or O · ,

[0469] Sp is the same or different each time it appears and represents a spacer group, and

[0470] W represents a straight-chain or branched-chain optionally unsaturated alkylene group having 1 to 12 C atoms, wherein one or more non-adjacent -CH2- groups may be replaced by -O-.

[0471] The preferred compound of formula H-1 is selected from the compounds of formula H-1-1:

[0472]

[0473] wherein R H has the meanings given above and preferably represents H or O · , and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0474] The preferred compound of formula H-2 is selected from the compounds of formula H-2-1:

[0475]

[0476] wherein R H has the meanings given above and preferably represents H or O · , and n2 is the same or different, preferably the same, an integer from 1 to 12, preferably 2, 3, 4, 5 or 6, very preferably 3, and R S is the same or different, preferably the same, represents an alkyl group having 1 to 6 carbon atoms, preferably n-butyl, each time it appears.

[0477] The preferred compound of formula H-3 is selected from the compounds of formula H-3-1:

[0478]

[0479] wherein R H has the meanings given above and preferably represents H or O · , and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0480] Preferably, the medium according to the invention comprises a stabilizer selected from the compounds of formula ST-1 to ST-19.

[0481]

[0482]

[0483]

[0484]

[0485]

[0486] wherein

[0487] R STrepresents H, an alkyl or alkoxy group having 1 to 15 C atoms, wherein additionally, one or more CH2 groups in these groups may each independently of one another be replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O-, -O-CO- in such a way that the O atoms are not directly linked to one another, and wherein additionally, one or more H atoms may be replaced by halogen,

[0488] represents

[0489]

[0490]

[0491] Z ST each independently of one another represents -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-, -CH2O-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond,

[0492] L 1 and L 2 each independently of one another represents F, Cl, CF3 or CHF2,

[0493] n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7,

[0494] n2, each time it occurs, is the same or different, preferably the same, and is an integer from 1 to 12, preferably 2, 3, 4, 5 or 6, very preferably 3, and

[0495] R S each time it occurs, is the same or different, preferably the same, and represents an alkyl group having 1 to 6 C atoms, preferably n-butyl,

[0496] p represents 1 or 2,

[0497] q represents 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0498] In the compounds of the formula ST, compounds of the following formula are particularly preferred

[0499]

[0500]

[0501] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 1 or 7

[0502]

[0503] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3

[0504]

[0505] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3

[0506]

[0507]

[0508]

[0509] In the compounds of formulae ST-3a and ST-3b, n preferably represents 3. In the compound of formula ST-2a, n preferably represents 7.

[0510] A very particularly preferred mixture according to the invention comprises a stabilizer selected from one or more compounds of formulae ST-2a-1, ST-3a-1, ST-3b-1, ST-8-1, ST-9-1 and ST-12:

[0511]

[0512]

[0513] The compounds of formulae ST-1 to ST-19 are preferably each present in the liquid crystal mixture according to the invention in an amount of 0.005 - 0.5% based on the mixture.

[0514] If the mixture according to the invention comprises two or more compounds selected from the compounds of formulae ST-1 to ST-19, then in the case of two compounds, the concentration is increased accordingly to 0.01 - 1% based on the mixture.

[0515] However, based on the mixture according to the invention, the total proportion of the compounds of formulae ST-1 to ST-19 should not exceed 2%.

[0516] In another preferred embodiment of the invention, the liquid crystal medium additionally comprises one or more polymerizable compounds. The polymerizable compounds are preferably selected from formula M

[0517] R a -B 1 -(Z b -B 2 ) m -Rb M

[0518] where each group, each time it occurs, is the same or different and each independently of the others has the following meanings:

[0519] R a and R b is P, P-Sp-, H, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, SF5 or a straight-chain or branched alkyl group having 1 to 25 C atoms, where, furthermore, one or more non-adjacent CH2 groups can each independently of the others 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 linked to one another, and where, furthermore, one or more H atoms can be replaced by F, Cl, Br, I, CN, P or P-Sp-, where, if B 1 and / or B 2 contains saturated C atoms, R a and / or R b can also represent a group spiro-linked to this saturated C atom,

[0520] where at least one of the groups R a and R b represents or contains the group P or P-Sp-,

[0521] P is a polymerizable group,

[0522] Sp is a spacer group or a single bond,

[0523] B 1 and B 2 are preferably aromatic, heteroaromatic, cycloaliphatic or heterocyclic groups having 4 to 25 ring atoms, which can also contain fused rings and which are unsubstituted or mono- or polysubstituted by L,

[0524] 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-, CR0 R 00 or a single bond,

[0525] R 0 and R 00 each independently of one another represent H or an alkyl group having 1 to 12 C atoms,

[0526] m represents 0, 1, 2, 3 or 4,

[0527] n1 represents 1, 2, 3 or 4,

[0528] L is P, P-Sp-, OH, CH2OH, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x )2, -C(=O)Y 1 , -C(=O)R x , -N(R x )2, an optionally substituted silyl group, an optionally substituted aryl group having 6 to 20 C atoms, or a straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 25 C atoms, where, furthermore, one or more H atoms may be replaced by F, Cl, P or P-Sp-,

[0529] P and Sp have the meanings given above,

[0530] Y 1 represents a halogen,

[0531] R x represents P, P-Sp-, H, a halogen, a straight-chain, branched or cyclic alkyl group having 1 to 25 C atoms, where 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 linked to one another, where 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 to 40 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 40 C atoms.

[0532] Particularly preferred compounds of the formula I are those in which B 1 and B 2Each independently represents 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl, naphthalene-2,6-diyl, phenanthrene-2,7-diyl, 9,10-dihydrophenanthrene-2,7-diyl, anthracene-2,7-diyl, fluorene-2,7-diyl, coumarin, flavone, wherein, in addition, one or more CH groups in these groups may be replaced by N, cyclohexane-1,4-diyl, wherein, in addition, one or more non-adjacent CH₂ groups may be replaced by O and / or S, 1,4-cyclohexenylene, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, piperidine-1,4-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, indane-2,5-diyl or octahydro-4,7-methanoindane-2,5-diyl, and all of these groups may be unsubstituted or mono- or poly-substituted by L as defined above.

[0533] Particularly preferred compounds of formula M are those in which B 1 and B 2 each independently represent 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl.

[0534] Very preferred compounds of formula M are selected from the following formulas:

[0535]

[0536]

[0537]

[0538]

[0539]

[0540] wherein each group is the same or different each time it appears, and each independently has the following meanings:

[0541] P 1 、P 2 、P 3 are polymerizable groups, preferably selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloropropionate, oxetanyl or epoxy group,

[0542] Sp 1 、Sp 2 and Sp 3 are single bonds or spacer groups, wherein, in addition, the group P 1 -Sp 1 -、P2 -Sp 2 - and P 3 -Sp 3 - one or more of which may also represent R aa provided that the group P present 1 -Sp 1 -, P 2 -Sp 2 and P 3 -Sp 3 - at least one of which is different from R aa and preferably represents -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -CO-O- or -(CH2) p1 -O-CO-O-, where p1 is an integer from 1 to 12.

[0543] R aa represents H, F, Cl, CN or a straight-chain or branched alkyl group having 1 to 25 C atoms, where, furthermore, one or more non-adjacent CH2 groups may independently of one another be replaced by -C(R 0 )=C(R 00 )-, -C≡C-, -N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly connected to each other, and where, furthermore, one or more H atoms may be replaced by F, Cl, CN or P 1 -Sp 1 -, especially preferably a straight-chain or branched optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 12 C atoms (where the alkenyl and alkynyl groups have at least two C atoms and the branched groups have at least three C atoms),

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

[0545] R y and R z are H, F, CH3 or CF3,

[0546] X 1 、X 2 、X 3 are -CO-O-, -O-CO- or a single bond,

[0547] Z M1 is -O-, -CO-, -C(Ry R z )- or -CF2CF2-,

[0548] Z M2 、Z M3 is -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -(CH2) n -, where n is 2, 3 or 4,

[0549] L is F, Cl, CN or a straight-chain or branched-chain, optionally mono- or poly-fluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms,

[0550] L’, L” are H, F or Cl,

[0551] r is 0, 1, 2, 3 or 4,

[0552] s is 0, 1, 2 or 3,

[0553] t is 0, 1 or 2,

[0554] x is 0 or 1.

[0555] Particularly preferred are the compounds of formula M2 and M13.

[0556] Further preferred are the tri-reactive compounds M15 to M31, especially M17, M18, M19, M22, M23, M24, M25, M30 and M31.

[0557] In the compounds of formulae M1 to M31, the group where L has one of the above meanings and r represents 0, 1, 2, 3 or 4 Specifically represents

[0558]

[0559]

[0560] where L is the same or different in each occurrence and has one of the meanings given in the context, and is preferably F, Cl, CN, NO2, CH3, C2H5, C(CH3)3, CH(CH3)2, CH2CH(CH3)C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5 or P-Sp-, very preferably F, Cl, CN, CH3, C2H5, OCH3, COCH3, OCF3 or P-Sp-, more preferably F, Cl, CH3, OCH3, COCH3 or OCF3, especially F or CH3.

[0561] Preferred compounds of formulas M1 to M31 are those in which P 1 , P 2 and P 3 represent acrylate, methacrylate, oxetanyl or epoxy groups, very preferably acrylate or methacrylate groups.

[0562] Further preferred compounds of formulas M1 to M31 are those in which Sp 1 , Sp 2 and Sp 3 are single bonds.

[0563] Further preferred compounds of formulas M1 to M31 are those in which one of Sp 1 , Sp 2 and Sp 3 is a single bond and the other of Sp 1 , Sp 2 and Sp 3 is different from a single bond.

[0564] Further preferred compounds of formulas M1 to M31 are those in which the groups Sp 1 , Sp 2 and Sp 3 different from single bonds represent -(CH2) s1 -X"- where s1 is an integer from 1 to 6, preferably 2, 3, 4 or 5, and X" is a linking group to the benzene ring and is -O-, -O-CO-, -CO-O, -O-CO-O- or a single bond.

[0565] Particularly preferred is a liquid crystal medium comprising one, two or three polymerizable compounds of formula M, preferably selected from formulas M1 to M31.

[0566] Further preferably, the liquid crystal medium according to the invention comprises one or more polymerizable compounds selected from the following Table E.

[0567] Preferably, the proportion of the polymerizable compound in the liquid crystal medium is 0.01 - 5%, very preferably 0.05 - 1%, most preferably 0.1 - 0.5%, and the polymerizable compound is preferably selected from formula M and Table E.

[0568] It has been observed that the addition of one or more polymerizable compounds, such as those selected from formula M and Table E, to a liquid crystal medium results in advantageous properties such as fast response times. Such liquid crystal media are particularly suitable for PSA displays, in which they exhibit low image sticking, fast and complete polymerization, rapid generation of a low pretilt angle that is stable after UV exposure, high reliability, a high VHR value after UV exposure, and a high birefringence. By appropriately selecting the polymerizable compounds, the absorption of the liquid crystal medium at longer UV wavelengths can be increased, such that such longer UV wavelengths can be used for polymerization, which is advantageous for display manufacturing methods.

[0569] 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, for example, groups that add or condense 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, for example, oxetanyl or epoxy groups.

[0570] Preferred P groups are selected from the group consisting of: 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 6Si-, 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 represent H or an alkyl group having 1 - 5 C atoms, especially H, methyl, ethyl or n-propyl, W 4 、W 5 and W 6 each independently of one another represent Cl, an oxaalkyl group or an oxacarbonylalkyl group having 1 to 5 C atoms, W 7 and W 8 each independently of one another represent H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, which is optionally substituted by one or more groups L as defined above, said 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.

[0571] Very preferably, the P group is 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 = CW 1 -CO-NH-, (CH2 = CH)2CH-OCO-, (CH2 = CH-CH2)2CH-OCO-, (CH2 = CH)2CH-O-, (CH2 = CH-CH2)2N-, (CH2 = CH-CH2)2N-CO-, CH2 = CW 1 -CO-NH-, CH2 = CH-(COO) k1 -Phe-(O) k2 -, CH2 = CH-(CO) k1 -Phe-(O) k2 -, Phe-CH = CH- and W 4 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF3, phenyl or an alkyl group having 1 to 5 C atoms, especially H, F, Cl or CH3, W 2 and W 3 each independently of one another represent H or an alkyl group having 1 to 5 C atoms, especially H, methyl, ethyl or n-propyl, W4 , W 5 and W 6 each independently of one another represents Cl, an oxaalkyl or an oxacarbonylalkyl having 1 to 5 C atoms, W 7 and W 8 each independently of one another represents H, Cl or an alkyl 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.

[0572] Very particularly preferred P groups are selected from the group consisting of: CH2 = CW 1 -CO-O-, in particular 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-,

[0573] Further preferred polymerizable groups P are selected from the group consisting of: vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetanyl and epoxy, most preferably selected from acrylate and methacrylate.

[0574] If Sp is different from a single bond, it is preferably of the formula Sp"-X", so that the corresponding group P-Sp- conforms to the formula P-Sp"-X", where,

[0575] Sp" represents an alkylene 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 wherein, furthermore, one or more non-adjacent CH2 groups can 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,

[0576] X" represents -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CO-N(R 0 ), N(R0 )-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,

[0577] R 0 and R 00 each independently of one another represent H or an alkyl group having 1 to 20 C atoms, and

[0578] Y 2 and Y 3 each independently of one another represent H, F, Cl or CN.

[0579] 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.

[0580] 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, R 0 and R 00 have the above meanings.

[0581] 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.

[0582] 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, ethylene-N-methylimino-ethylene, 1-methylalkylene, vinylidene, propenylene and butenylene.

[0583] For the production of PSA displays, the polymerizable compounds comprised in the liquid-crystalline medium are polymerized or crosslinked (if a compound comprises 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.

[0584] The construction of the PSA displays according to the invention corresponds to the usual geometry of PSA displays, as described in the prior art cited at the beginning. Geometries without protrusions are preferred, in particular those in which additionally the electrodes on the color filter side are unstructured and only the electrodes on the TFT side have grooves. Particularly suitable and preferred electrode structures of PS-VA displays are described, for example, in US2006 / 0066793 A1.

[0585] The combination of the compounds of the above-described preferred embodiments with the above-described polymerized compounds gives in the liquid-crystalline medium according to the invention a low threshold voltage, a low rotational viscosity and very good low-temperature stability, while giving constant high-definition bright dots and a high VHR value.

[0586] The use of a liquid-crystalline medium containing polymerizable compounds allows a particularly low pretilt angle to be established rapidly in PSA displays. In particular, compared with the media of the prior art, in PSA displays the liquid-crystalline medium exhibits a significantly shortened response time, in particular also the gray-scale response time.

[0587] In a further preferred embodiment, the medium according to the invention comprises, individually or in combination with one another, the following compounds, where the acronyms are explained in Table D below:

[0588] - one, two or more compounds of formula I, in a total concentration in the range from 0.5 to 10%, preferably from 1 to 7%, particularly preferably from 2 to 5%;

[0589] - one or more compounds of formula II, preferably a compound of formula II-1, more preferably a sub-formula II-1a and / or II-1f and / or II-1g and / or II-1h compound, in particular a compound of formula II-1a-1 and II-1f-1 and II-1h-1, or a compound of formula II-1f-1 and II-1g-1 and II-1h-1, preferably in a total concentration in the range from 3 to 20%, preferably from 5 to 18%, particularly preferably from 7 to 15%;

[0590] and / or

[0591] - one or more compounds of formula III, with a total concentration in the range of 0.1 - 10%, preferably 0.2 - 7%, more preferably 0.3 - 2%, preferably selected from compounds of formula III-2, more preferably compounds of formula III-2c and / or III-2i and / or III-2l and / or III-2m, very preferably compounds of formula III-2c-4 and / or III-2i-3 and / or III-2l-3 and / or III-2m-1, especially compounds of formula III-2i-3 and III-2m-1, wherein the concentration of the compound(s) of formula III-2m-1 is very preferably 1% or less;

[0592] and / or

[0593] - one or more compounds of formula YA, preferably compounds of formula YA-2 and / or YA-10, with a total concentration in the range of 1 - 10%, preferably 2 - 8%, particularly preferably 3 - 7%;

[0594] and / or

[0595] - one or more compounds of formula YD, preferably compounds of formula YD-7 and / or YD-10, with a total concentration in the range of 1 - 10%, preferably 2 - 8%, particularly preferably 3 - 7%;

[0596] and / or

[0597] - one or more compounds of formula YB, preferably compounds of formula YB-2 and / or YB-10, with a total concentration in the range of 0.5 - 10%, preferably 1 - 7%, particularly preferably 2 - 5%;

[0598] and / or

[0599] - one or more compounds of formula I and YD and optionally YA, preferably compounds selected from formula YA-2, YA-10, YD-7 and YD-10, with a total concentration in the range of 1 - 20%, preferably 3 - 17%, particularly preferably 4 - 14%;

[0600] and / or

[0601] - one or more compounds of formula B, preferably B-8, very preferably formula LB(S)-n-OT, especially LB(S)-3-OT, with a total concentration in the range of 0.1 - 10%, preferably 0.5 - 5%, particularly preferably 1 - 4%;

[0602] and / or

[0603] - one or more compounds of formula IV-1 less than 5%, preferably less than 3%, very preferably less than 1%;

[0604] and / or

[0605] -One or more compounds of Formula IV, preferably a compound of Formula IV-3, with a total concentration in the range of 20 - 70%, more preferably 30 - 60%, most preferably 33 - 50%, preferably selected from compounds of Formula IV-3-1 to IV-3-6, especially selected from compounds of Formula IV-3-1, IV-3-2, IV-3-4 and IV-3-6;

[0606] and / or

[0607] -0.5 - 8%, preferably 1 - 6% of compound IV-3-6 (CC-3-2V1) or IV-3-4 (CC-4-V1);

[0608] and / or

[0609] -One or more compounds of Formula IVa, preferably a compound of Formula IVa-2, preferably with a total concentration in the range of 0.1 - 3%, more preferably 0.2 - 2%;

[0610] and / or

[0611] -One or more compounds of Formula IVb, preferably a compound of Formula IVb-2, most preferably a compound of Formula IVb-2-3, preferably with a total concentration in the range of 0.2 - 8%, more preferably 0.5 - 7%, especially 1 - 6%;

[0612] and / or

[0613] One or more compounds of Formula V, preferably selected from compounds V-1-1, V-1-6, V-2-1, V-2-2, V-2-3, V-2-4, V-3-4 and V-4-1, preferably with a total concentration in the range of 5 - 50%, preferably 10 - 40%, especially 15 - 33%;

[0614] and / or

[0615] One or more compounds of Formula CL, preferably selected from compounds of Formula CL-3, preferably with a total concentration in the range of 1 - 15%, preferably 2 - 12%, especially 3 - 10%;

[0616] and / or

[0617] One or more compounds of Formula V and one or more compounds of Formula CL, preferably with a total concentration in the range of 5 - 50%, preferably 10 - 40%, especially 15 - 33%;

[0618] and / or

[0619] One or more compounds of formula V-1-1 or IV-1-6, preferably selected from compounds CCC-n-V, CCC-V-V and CVCC-n-m, preferably in a total concentration in the range of 0.5 - 10%, preferably 0.75 - 7%, especially 1 - 5%;

[0620] and / or

[0621] One or more compounds of formula V-2-1 and / or V-2-2, preferably CCP-n-m and / or CCP-Vn-m and / or CPP-n-m, very particularly selected from CCP-3-1, CCP-V-1 and CCP-V2-1, preferably in a total concentration in the range of 8 - 20%, more preferably 12 - 17%, very preferably 15 - 27%;

[0622] and / or

[0623] One or more compounds of formula VII, preferably compounds of formula VII-1-20 and / or VII-1-21, preferably in a total concentration in the range of 1 - 15%, preferably 2 - 10%, especially 3 - 7%;

[0624] and / or

[0625] One or more compounds of formula VIII, preferably compounds selected from formula VIII-3, more preferably VIII-3a, preferably in a total concentration in the range of 2 - 20%, preferably 5 - 17%, especially 8 - 14%;

[0626] The liquid crystal medium according to the invention, while maintaining a nematic phase down to -20 °C, preferably down to -30 °C, particularly preferably down to -40 °C, and a clearing point ≥ 75 °C, preferably ≥ 79 °C, allows a rotational viscosity γ1 ≤ 80 mPa·s to be obtained, particularly preferably ≤ 70 mPa·s, such that an excellent MLC display with a fast response time can be obtained. The rotational viscosity is measured at 20 °C.

[0627] The dielectric anisotropy Δε of the liquid crystal medium according to the invention at 20 °C and 1 kHz is preferably ≥ +1.5, preferably in the range of 1.5 to 8, more preferably in the range of 2.0 to 6.0, very preferably 2.5 to 4.6, particularly preferably 3.0 to 4.4.

[0628] The birefringence Δn of the liquid crystal medium according to the invention is preferably 0.080 to 0.140, very preferably 0.090 to 0.135, especially 0.091 to 0.132.

[0629] In a preferred embodiment of the invention, the birefringence of the medium is 0.080 to 0.100, very preferably 0.085 to 0.098, especially 0.090 to 0.094.

[0630] In a preferred embodiment of the present invention, the birefringence of the medium is from 0.110 to 0.130, very preferably from 0.119 to 0.128, especially from 0.120 to 0.123.

[0631] In a preferred embodiment of the present invention, the birefringence of the medium is from 0.120 to 0.140, very preferably from 0.125 to 0.135, especially from 0.129 to 0.132.

[0632] The rotational viscosity γ1 of the liquid crystal medium according to the present invention is preferably ≤120 mPa·s, more preferably ≤110 mPa·s, very preferably ≤105 mPa·s.

[0633] The ratio γ1 / K1 of the liquid crystal medium according to the present invention is preferably ≤5.5 mPa·s / pN, more preferably ≤5.3 mPa·s / pN, very preferably ≤5.0 mPa·s / pN.

[0634] In the present text, the structures of mesogenic compounds are represented by abbreviations, which are also called acronyms. In these abbreviations, chemical formulas are abbreviated using Tables A to C below. All groups C n H 2n+1 、C m H 2m+1 and C l H 2l+1 and C n H 2n-1 、C m H 2m-1 and C l H 2l-1 represent straight-chain alkyl or alkylene groups having n, m, and l carbon atoms, respectively, in each case, where n and m are independently 1, 2, 3, 4, 5, 6, or 7, and l is 1, 2, or 3. Table A lists the codes for the ring elements of the core structures of the compounds, while Tables B and C show the linking groups and end groups. Table D shows exemplary structures of the compounds and their corresponding abbreviations.

[0635] Table A: Ring elements

[0636]

[0637]

[0638]

[0639] Table B: Linking groups

[0640]

[0641]

[0642] Table C: End groups

[0643]

[0644]

[0645] Used in combination with others

[0646]

[0647] where n and m each represent an integer, and the three dots "…" are placeholders for other abbreviations from the table.

[0648] Table D

[0649]

[0650]

[0651]

[0652]

[0653]

[0654]

[0655]

[0656]

[0657]

[0658]

[0659]

[0660]

[0661]

[0662]

[0663]

[0664]

[0665]

[0666]

[0667]

[0668]

[0669]

[0670]

[0671]

[0672]

[0673]

[0674]

[0675]

[0676]

[0677]

[0678]

[0679]

[0680] In a preferred embodiment of the present invention, the medium comprises one or more compounds selected from the compounds of Table D.

[0681] Table E shows the chiral dopants preferably used in the mixtures according to the present invention.

[0682] Table E

[0683]

[0684]

[0685]

[0686] Preferably, the medium according to the present invention comprises one or more compounds selected from the compounds of Table E.

[0687] Table F

[0688] Table F shows exemplary reactive mesogenic compounds (RM) that can be used in the LC media according to the present invention.

[0689]

[0690]

[0691]

[0692]

[0693]

[0694]

[0695]

[0696]

[0697]

[0698]

[0699]

[0700]

[0701]

[0702]

[0703]

[0704]

[0705]

[0706]

[0707]

[0708] In a preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds, preferably selected from the polymerizable compounds of formulas RM-1 to RM-182. Among them, the compounds RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM-40, RM-41, RM-48, RM-52, RM-54, RM-57, RM-58, RM-64, RM-74, RM-76, RM-88, RM-91, RM-102, RM-103, RM-109, RM-116, RM-117, RM-120, RM-121, RM-122, RM-139, RM-140, RM-142, RM-143, RM-145, RM-146, RM-147, RM-149, RM-156 to RM-163, RM-169, RM-170 and RM-171 to RM-183 are particularly preferred. Detailed Description of the Invention

[0709] Working examples:

[0710] The following examples are intended to illustrate the invention and not to limit it. In the examples, m.p. represents the melting point of the liquid crystal substance in degrees Celsius, and T (N,I) represents the clearing point of the liquid crystal substance in degrees Celsius; in addition, C represents the crystalline solid state, S represents the smectic phase (the index represents the phase type), N represents the nematic state, Ch represents the cholesteric phase, I represents the isotropic phase, Tg represents the glass transition temperature. The number between two symbols represents the transition temperature in degrees Celsius.

[0711] The host mixture for determining the optical anisotropy Δn of a single compound is the commercial mixture ZLI-4792 (Merck KGaA). The dielectric anisotropy Δε is determined using the commercial mixture ZLI-2857. The physical data of the compound to be studied are obtained by changing the dielectric constant of the host mixture after adding the compound to be studied and extrapolating to 100% of the compound used. Usually, 10% of the compound to be studied is dissolved in the host mixture, depending on solubility.

[0712] Unless otherwise specified, parts or percentage data represent parts by weight or percentages by weight.

[0713] In the context:

[0714] V0 represents the threshold voltage at 20 °C, capacitive [V],

[0715] n e represents the extraordinary refractive index at 20 °C and 589 nm,

[0716] no represents the ordinary refractive index at 20 °C and 589 nm,

[0717] Δn represents the optical anisotropy (birefringence) at 20 °C and 589 nm,

[0718] ε ⊥ represents the dielectric constant perpendicular to the director at 20 °C and 1 kHz,

[0719] ε|| represents the dielectric constant parallel to the director at 20 °C and 1 kHz

[0720] Δε represents the dielectric anisotropy at 20 °C and 1 kHz,

[0721] cl.p., T(N,I) represents the clearing point [°C],

[0722] γ1 represents the rotational viscosity measured at 20 °C [mPa·s],

[0723] K1 represents the elastic constant, the "splay" deformation at 20 °C [pN],

[0724] K2 represents the elastic constant, the "twist" deformation at 20 °C [pN],

[0725] K3 represents the elastic constant, the "bend" deformation at 20 °C [pN],

[0726] K av represents the average elastic constant at 20 °C, defined as and

[0727] LTS represents the low temperature stability (nematic phase), determined in a test cell or bulk as specified.

[0728] Unless otherwise explicitly stated, all temperature values indicated in this application, such as the melting point T(C,N), the transition point T(S,N) from the smectic phase (S) to the nematic phase (N), and the clearing point T(N,I) or cl.p. are expressed in degrees Celsius (°C).

[0729] The term "threshold voltage" used in this invention refers to the capacitive threshold (V0), which is also referred to as the Freedericksz threshold, unless otherwise specified. In the examples, the optical threshold is also given as usual for a 10% relative contrast (V 10 ).

[0730] The display for measuring the capacitive threshold voltage consists of two parallel planar glass outer plates spaced 20 μm apart, each having an electrode layer on the inside and an unrubbed polyimide alignment layer on the top, which results in a homeotropic edge alignment of the liquid crystal molecules.

[0731] The display or test cell for measuring the tilt angle consists of two plane-parallel glass outer plates spaced 4 μm apart, each having an electrode layer on the inner side and a polyimide alignment layer on the top, where the two polyimide layers are rubbed antiparallel to each other and cause homeotropic edge alignment of liquid crystal molecules.

[0732] The polymerizable compound is polymerized in the display or test cell by irradiating with UV light of a specified intensity for a predetermined time while applying a voltage (usually 10 V to 30 V alternating current, 1 kHz) to the display. In the examples, unless otherwise stated, a metal halide lamp with an intensity of 100 mW / cm 2 is used for polymerization. The intensity is measured using a standard measuring instrument (a high-end Hoenle UV-meter with a UV sensor).

[0733] The tilt angle is determined using the Mueller matrix polarimeter "AxoScan" from Axometrics. Here, a low value (i.e., a large deviation from the 90° angle) corresponds to a large tilt.

[0734] Unless otherwise stated, the term "tilt angle" refers to the angle between the LC director and the substrate, and "LC director" refers to the preferred orientation direction of the optical axes of LC molecules in a layer of LC molecules with a uniform orientation, which corresponds to their molecular long axes in the case of rod-shaped, uniaxial positive birefringent LC molecules.

[0735] Unless otherwise stated, VHR is measured in a commercially available instrument Model LCM-1 (O0004) from TOYO Corporation, Japan, at 20 °C (VHR 20 ) and after being placed in an oven at 100 °C for 5 minutes (VHR 100 ). Unless otherwise specified more precisely, the frequency range of the voltage used is 1 Hz to 60 Hz.

[0736] The stability against UV irradiation is studied using a xenon lamp NXE1500B in a commercially available instrument "Suntest CPS+" from Heraeus, Germany. Unless otherwise explicitly stated, the sealed test cells are irradiated for 2.0 hours without additional heating. The radiant power in the wavelength range 300 nm to 800 nm is 765 W / m 2 V. A UV "cut-off" filter with a 310 nm edge wavelength is used to simulate the so-called window glass mode. In each series of experiments, at least four test cells are studied for each condition, and the corresponding results are expressed as the average of the corresponding individual measurements.

[0737] The reduction in the voltage holding ratio (ΔVHR) usually caused by exposure (e.g., by UV irradiation or through LCD backlighting) is determined according to the following equation (1):

[0738] ΔVHR(t) = VHR(t) - VHR(t = 0) (1)

[0739] To study the low temperature stability (also referred to as "LTS"), i.e., the stability of the liquid crystal mixture in the bulk against the spontaneous crystallization of individual components or the appearance of a smectic phase (as the case may be) at low temperatures, several sealed vials (each containing approximately 1 g of material) are stored at one or more given temperatures, typically -10°C, -20°C, -30°C, and / or -40°C, and visually inspected regularly for the observation of a phase change. Once a change occurs in the first sample at a given temperature, the test is not continued. And the time until no change is observed at the last inspection is recorded as the corresponding LTS. The test run lasts for 1000 hours. If no change occurs after 1000 hours, the result is "LTS > 1000 hours"

[0740] The ion density required for calculating the resistivity is measured using a commercially available LC Material Characteristics Measurement System Model 6254 from Toyo Corporation, Japan, with a cell gap of 3.2 μm and a VHR test cell with AL16301 Polyimide (JSR Corp., Japan). The measurement is carried out after storing in an oven at 60°C or 100°C for 5 minutes.

[0741] The so-called "HTP" represents the helical twisting power (in μm) of the optically active or chiral substance in the LC medium. Unless otherwise specified, the HTP is measured in a commercially available nematic LC host mixture MLD - 6260 (Merck KGaA) at a temperature of 20°C.

[0742] The clearing point was measured using a Mettler Thermosystem FP900. The optical anisotropy (Δn) was measured using an Abbe Refractometer H005 (Natrium-spectral lamp Na10, 589 nm, 20 °C). The dielectric anisotropy (Δε) was measured using an LCR-Meter E4980A / Agilent (G005) at 20 °C (ε-parallel cell with JALS2096-R1). The threshold voltage (V0) was measured using an LCR-Meter E4980A / Agilent (G005) at 20 °C (ε-parallel cell with JALS2096-R1). The rotational viscosity (γ1) was measured using a TOYO LCM-2 (0002) at 20 °C (γ1 negative cell with JALS2096-R1). The elastic constant (K1, splay) was measured using an LCR-Meter E4980A / Agilent (G005) at 20 °C (ε-parallel cell with JALS2096-R1). K3: The elastic constant (K3, bend) was measured using an LCR-Meter E4980A / Agilent (G005) at 20 °C (ε-parallel cell with JALS2096-R1).

[0743] Unless otherwise explicitly stated, all concentrations in this application are given as weight percentages and relate to the respective overall mixture, which contains all solid or liquid crystal components and no solvent. Unless otherwise explicitly stated, all physical properties were determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status November 1997, Merck KGaA, Germany and apply to a temperature of 20 °C.

[0744] The following mixture examples with positive dielectric anisotropy are particularly suitable for liquid crystal displays with at least one planar alignment layer, such as IPS and FFS displays, especially UB-FFS (= ultra-bright FFS), and VA displays.

[0745] Examples

[0746] The compositions and physical properties of comparative mixture C-1 and nematic mixtures M-1 to M-12 are given in the table below. The compositions are given as weight percentages.

[0747] Comparative Example C1

[0748]

[0749]

[0750] Mixture example M1

[0751]

[0752] The key parameters of mixtures C1 and M1 are summarized in the following table.

[0753] Δε Δn <![CDATA[K av [pN]]]> <![CDATA[γ1[mPas]]]> <![CDATA[γ1 / K1[mPas / pN]]]> C1 3.1 0.0920 16.0 89 5.0 M1 3.2 0.0925 16.0 87 4.8

[0754] Surprisingly, it has been found that replacing the compound CCPC-3-3 of comparative mixture C1 with the compound CLPC-2-3 of formula I in mixture Example 1 enables a favorable lower rotational viscosity (γ1), while achieving a lower ratio γ1 / K1, which improves the response time of the display.

[0755] Mixture example M2

[0756]

[0757]

[0758] Mixture example M3

[0759]

[0760]

[0761] Mixture example M4

[0762]

[0763] Mixture example M5

[0764]

[0765]

[0766] Mixture example M6

[0767]

[0768] Mixture M7

[0769] Mixture M7 consists of 99.975% of mixture M1 and 250 ppm of stabilizer ST-3c

[0770]

[0771] Mixture M8

[0772] Mixture M8 consists of 99.975% of mixture M2, 150 ppm of stabilizer ST-3d, and 100 ppm of stabilizer ST-19a

[0773]

[0774] Mixture example M9

[0775]

[0776]

[0777] Mixture example M10

[0778]

[0779] Mixture example M11

[0780]

[0781]

[0782] Mixture example M12

[0783]

Claims

1. A liquid crystal medium comprising a) one or more compounds of formula I in R 11 and R 12 Identically or differently represent H, straight-chain alkyl or alkoxy groups having 1 to 15 C atoms, straight-chain alkenyl or alkenyloxy groups having 2 to 15 C atoms, or branched alkyl, alkoxy, alkenyl, alkenyloxy groups each having 3 to 15 C atoms, wherein one or more CH2 groups in these groups can each be independently replaced by -CH=CH-, -C≡C-, -CF2O-, -OCF2-, -O-, -CO-O- or -O-CO- are 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 replaced by halogen, L 11 and L 12 independently represent H, F, Cl, CH3, CF3 or CHF2; and b) one or more compounds selected from the group consisting of compounds of formula II and III in R 2 and R 3 independently of one another represent unsubstituted or halogenated straight-chain or branched alkyl or alkoxy radicals having 1 to 15 C atoms, wherein one or more CH2 radicals in these radicals can each independently of one another be -C≡C-, -CF2O-, -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, Independently express L 21 , L 22 , L 31 and L 32 independently of each other represent H or F, Y 2 and Y 3 Identically or differently represent H or CH3, X 2 and X 3 independently of one another represent halogen, haloalkyl or haloalkoxy having 1 to 3 C atoms, or haloalkenyl or haloalkenyloxy having 2 or 3 C atoms, Z 3 represents -CH2CH2-, -CF2CF2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CH2O-, or a single bond, and l, m, n and o are independently 0 or 1.

2. The medium according to claim 1, wherein L 11 and L 12 independently represents H or F.

3. A liquid crystal medium according to claim 1 or 2, wherein the medium comprises one or more compounds of the formula II selected from the group consisting of compounds of the formulae II-1, II-2 and II-3 in L 23 and L 24 Indicates H or F, and the remaining radicals have the meanings given under formula II in claim 1.

4. Liquid-crystalline medium according to one or more of claims 1 to 3, wherein the medium comprises one or more compounds of the formula III selected from the compounds of the formulae III-1 and III-2 Where R 3 , X 3 , L 31 , L 32 、Ring element A 31 , A 32 and A 33 and n and o have the meanings defined in claim 1 for formula III.

5. Liquid-crystalline medium according to one or more of claims 1 to 4, wherein the medium comprises one or more compounds selected from the group consisting of compounds of the formulae Y, B, BC, CR, PH-1 and PH-2: in R Y1 , R Y2 , R B1 , R B2 , R CR1 , R CR2 , R P1 and R P2 each independently of one another represents H, alkyl or alkoxy having 1 to 15 C atoms, wherein one or more CH2 groups in these radicals can each independently of one another be -CH=CH-, -C≡C-, -CF2O-, -OCF2-, -O-, -CO-O- or -O-CO- are 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 replaced by halogen, In each occurrence, they are expressed independently of each other a) 1,4-cyclohexenyl or 1,4-cyclohexylene, in which one or two non-adjacent CH2 groups may be replaced by -O- or -S-, b) 1,4-phenylene, in which one or both CH groups may be replaced by N, or c) a radical selected from the group consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octane-2,6-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, wherein the groups a), b) and c) may be mono- or poly-substituted by halogen atoms, Z x , Z y represent, identically or differently, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, Z 1 represents, independently of one another at each occurrence, -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-CH2O-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond, L 11 and L 12 each independently represents F, Cl, CF3 or CHF2, W means O or S, n is 0, 1, or 2, c is 0, 1, or 2, x and y are independently 0, 1 or 2, wherein x+y≤3.

6. Liquid-crystalline medium according to one or more of claims 1 to 5, wherein the medium comprises one or more compounds of the formula VII, in R 71 and R 72 represents H, F, a straight-chain alkyl or alkoxy group having 1 to 15 C atoms, a straight-chain alkenyl or alkenyloxy group having 2 to 15 C atoms, or a branched alkyl, alkoxy, alkenyl, alkenyloxy group each having 3 to 15 C atoms, wherein one or more CH2 groups in these groups may each be independently 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 wherein one or more H atoms may be replaced by halogen, X 71 , X 72 , X 73 , X 74 , X 75 and X 76 Identically or differently represent H or F, Z 71 and Z 72 Identically or differently represent CH2CH2 or a single bond.

7. Liquid-crystalline medium according to one or more of claims 1 to 6, wherein the medium comprises one or more compounds of the formula IV in R 11 represents a straight-chain alkyl group having 1 to 12 C atoms or a branched or cyclic alkyl group having 3 to 12 C atoms, or a straight-chain alkenyl group having 2 to 12 C atoms or a branched alkenyl group having 3 to 12 C atoms or a cyclic alkenyl group having 5 to 12 C atoms, wherein one or more H atoms are optionally replaced by fluorine, R 12 represents a straight-chain alkyl or alkoxy group having 1 to 12 C atoms or a branched or cyclic alkyl or alkoxy group having 3 to 12 C atoms, or a straight-chain alkenyl group having 2 to 12 C atoms or a branched alkenyl group having 3 to 12 C atoms or a cyclic alkenyl group having 5 to 12 C atoms, wherein one or more H atoms are optionally replaced by fluorine.

8. Liquid-crystalline medium according to one or more of claims 1 to 7, wherein the medium comprises one or more compounds of the formula IVa and / or IVb, in R 41 and R 42 each independently of one another represents straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkenyloxy having up to 12 C atoms, express Z 4 Represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -C4H8- or -CF=CF-.

9. Liquid-crystalline medium according to one or more of claims 1 to 8, wherein the medium comprises one or more compounds of the formula V in R 51 , R 52 represents an alkyl group having 1 to 7 C atoms, an alkoxy group having 1 to 7 C atoms or an alkoxyalkyl group, an alkenyl group or an alkenyloxy group having 2 to 7 C atoms, Same or different Z 51 , Z 52 Each independently represents -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, and n is 1 or 2.

10. Liquid-crystalline medium according to one or more of claims 1 to 9, wherein the medium comprises one or more compounds of the formula VIII in R 81 and R 82 Identically or differently represent H, halogen, CN, SCN, straight-chain alkyl or alkoxy radicals having 1 to 15 C atoms, straight-chain alkenyl or alkenyloxy radicals having 2 to 15 C atoms, or branched alkyl, alkoxy, alkenyl or alkenyloxy radicals having 3 to 15 C atoms, wherein one or more CH2 radicals in these radicals can each be independently 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 wherein one or more H atoms may be replaced by halogen, A 0 , A 81 and A 82 each independently of one another represents phenylene-1,4-diyl, in which 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, in which one or two non-adjacent CH2 groups may be replaced independently of one another 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; Z 81 and Z 82 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; n represents 0, 1, 2, or 3, and m represents 0, 1, 2 or 3.

11. A liquid crystal display, characterized in that: It comprises a liquid-crystalline medium according to one or more of claims 1 to 10 .

12. The liquid crystal display of claim 11, wherein the display is configured to operate in IPS or FFS mode.

13. Compounds of formula I in R 11 and R 12 Identically or differently represent H, straight-chain alkyl or alkoxy groups having 1 to 15 C atoms, straight-chain alkenyl or alkenyloxy groups having 2 to 15 C atoms, or branched alkyl, alkoxy, alkenyl, alkenyloxy groups each having 3 to 15 C atoms, wherein one or more CH2 groups in these groups can each be independently replaced by -CH=CH-, -C≡C-, -CF2O-, -OCF2-, -O-, -CO-O- or -O-CO- are 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 replaced by halogen, L 11 and L 12 represents H, F, Cl, CH3, CF3 or CHF2; where L 11 and L 12 Not all mean H, and if L 11 and L 12 One of the represents F, then L 11 and L 12 The other one is not Cl.

14. A method for preparing a compound of formula (I) according to claim 13, comprising at least the step of removing water from the compound of formula (3) Where R 11 , R 12 , L 11 and L 12 has the meaning given for formula I in claim 13.

15. A compound of formula (3) as defined in claim 14.

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