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, in particular to 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

Technical Field

[0001] The present invention relates to liquid crystal (LC) media having positive dielectric anisotropy and to liquid crystal displays (LCDs) containing these media, in particular to displays addressed by an active matrix and in particular to LC displays of the 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. Background Art

[0002] Liquid crystal displays (LCDs) are used in many fields for information display. LCDs are used for both direct view and projection displays. Electro-optical modes used are, for example, twisted nematic (TN), super twisted nematic (STN), optically compensated bend (OCB), and electrically controlled birefringence (ECB) modes and their various variations, as well as other modes. All of these modes employ 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, which employ an electric field substantially parallel to the substrate or liquid crystal layer. For example, WO 91 / 10936 discloses a liquid crystal display in which the electrical signal is generated in such a way that the electric field has a significant component parallel to the liquid crystal layer, and is therefore known as an in-plane switching (IPS) display. The principle of operating such a display is described, for example, by RA Soref in Journal of Applied Physics, Vol. 45, No. 12, pp. 5466-5468 (1974).

[0004] IPS displays contain an LC layer between two substrates with a planar orientation, wherein the two electrodes are arranged on only one of the two substrates and preferably have an interdigitated comb structure. When a voltage is applied to the electrodes, an electric field with a significant component parallel to the LC layer is generated between them. This leads to a realignment of the LC molecules in the layer plane.

[0005] For example, EP 0 588 568 discloses various possibilities for designing electrodes and for addressing IPS displays. DE 198 24 137 likewise describes various embodiments of such IPS displays.

[0006] Liquid-crystal materials for IPS displays of this type are described in DE 195 28 104, for example.

[0007] Furthermore, so-called "fringe field switching" (FFS) displays have been reported (see, inter alia, SH Jung et al., Jpn. J. Appl. Phys., Vol. 43, No. 3, 2004, 1028), which comprise two electrodes on the same substrate, one of which is structured in a comb-like manner and the other of which is unstructured. This results in a strong so-called "fringe field", i.e. a strong electric field close to the edges of the electrodes and an electric field with both a strong vertical component and a strong horizontal component throughout the liquid crystal cell. FFS displays have a low viewing angle dependence of the contrast. FFS displays typically comprise an LC medium with positive dielectric anisotropy and an alignment layer, typically of polyimide, which provides a planar alignment for the molecules of the LC medium.

[0008] Liquid crystal displays in the IPS and FFS electro-optical modes are particularly suitable for modern desktop monitors, televisions and multimedia applications, but are also used in mobile phones and tablet PCs etc. The liquid crystal media according to the invention are preferably used in displays of this type. Usually, dielectrically positive liquid crystal media with rather low dielectric anisotropy values ​​are used in FFS displays, but in some cases liquid crystal media with dielectric anisotropies of only about 3 or even lower are also used in IPS displays.

[0009] Further improvements have been achieved through the so-called HB-FFS mode. One of the unique features of the HB-FFS mode is its ability to allow higher transmittances compared to conventional FFS technology, which allows the panel to operate with less energy consumption.

[0010] Liquid crystal compositions suitable for LCDs and in particular for FFS and IPS displays are known from the prior art, for example from JP 07-181 439 (A), EP 0 667 555, EP 0 673 986, DE 195 09 410, DE 195 28106, DE 195 28 107, WO 96 / 23 851 and WO 96 / 28 521. However, these compositions have certain disadvantages. Among other disadvantages, most of them lead to disadvantageously long addressing times, have insufficient resistivity values ​​and / or require too high an operating voltage. Improvements in both operating properties and shelf life are necessary here.

[0011] FFS and IPS displays can be operated as active matrix displays (AMD) or passive matrix displays (PMD). In the case of active matrix displays, the individual pixels are typically addressed by integrated non-linear active elements such as thin film transistors (TFTs), while in the case of passive matrix displays, the individual pixels are typically addressed by multiplexing methods known in the art.

[0012] The display according to the invention is preferably addressed by an active matrix, preferably by a matrix of TFTs. However, the liquid crystals according to the invention can also be advantageously used in displays having other known addressing means.

[0013] Both IPS and FFS technologies have certain advantages over other LCD technologies, such as vertical alignment (VA) technology, such as a wide viewing angle dependency of the contrast ratio. Summary of the invention

[0014] The provision of further liquid crystal media and their use in displays with high transmittance, a good black state and a high contrast ratio are core challenges for modern FFS and IPS applications. In addition, modern applications also require good low temperature stability and fast addressing times. The contrast ratio can be improved by higher transmittance in the bright state and a better dark state. One solution to improve the dark state is to develop liquid crystal media with a higher K Avg . mixture to reduce the scattering parameters of the LC mixture, but this usually has the disadvantage of shortening the response time.

[0015] It is observed that by using a liquid crystal having positive dielectric anisotropy and having an increased dielectric constant ε perpendicular to the longitudinal axis of the liquid crystal molecules ⊥ Liquid crystal media with high brightness can achieve displays such as those in HB-FFS mode. This can be achieved by adding a limited amount of liquid crystal compounds with negative dielectric anisotropy (the compounds have high ε ⊥ properties) while maintaining a positive dielectric anisotropy throughout the medium. However, adding ⊥ There are some disadvantages of compounds with γ1. For example, this may lead to higher values ​​of the rotational viscosity γ1 and cause the rotational viscosity γ1 and the elastic constant K of the torsional deformation to 22 The ratio of γ1 / K 22 higher, which results in a higher response time. 22 The elastic constant K of the splay deformation 11 Approximately proportional to (K 22 The value is usually about K 11 half of its value), so by measuring γ1 and K 11 Easily determined.

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

[0017] The present invention has the object of providing liquid-crystalline media, preferably for FFS and IPS displays, in particular for HB-FFS displays, but also for TN, positive VA or STN displays, in particular for active-matrix displays (such as those addressed by means of TFTs), which do not exhibit the above-mentioned disadvantages or only to a lesser extent, and in particular to provide media which enable displays to have an improved contrast, preferably without deteriorating other display parameters.

[0018] In order to solve the above problems, the present invention provides a liquid crystal medium according to claim 1 .

[0019] Advantageous embodiments of the invention are the subject matter of the dependent claims or can also be taken from the description.

[0020] The present invention relates to a liquid crystal medium having positive dielectric anisotropy, comprising

[0021] a) one or more compounds of formula I

[0022]

[0023] in

[0024] R 11 , R 12 Identically or differently represent straight-chain alkyl radicals having 1 to 12 C atoms or branched alkyl radicals having 3 to 12 C atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly connected to one another, and wherein in addition one or more H atoms may be replaced by halogen, preferably alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms,

[0025] express

[0026]

[0027] Best

[0028] Y 1 represents H or CH3, preferably H,

[0029] n is 0 or 1, preferably 1,

[0030] v is 1, 2, 3, 4, 5, or 6;

[0031] and

[0032] b) one or more compounds selected from the group consisting of compounds of formula II and III

[0033]

[0034] in

[0035] R 2 and R 3 With the above R 11 The meanings given above preferably denote alkyl having 1 to 7 C atoms, or alkenyl having 2 to 7 C atoms,

[0036]

[0037] Independently express

[0038]

[0039] L 21 , L 22 , L 31 and L 32 independently of each other represent H or F,

[0040] Y 2 and Y 3 Identically or differently represent H or CH3, preferably H,

[0041] 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, preferably F, Cl, CF3, OCF3 or OCHF2, more preferably F or OCF3,

[0042] Z 3 represents -CH2CH2-, -CF2CF2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CH2O- or a single bond, preferably a single bond, and

[0043] l, m, n and o are independently 0 or 1.

[0044] The combination of the compound of formula I with the compound of formula II and / or III enables the liquid crystal medium to exhibit a moderately positive dielectric anisotropy while increasing the dielectric constant ε perpendicular to the longitudinal axis of the liquid crystal molecules. ⊥ , while maintaining low rotational viscosity and low γ1 / K 22 and γ1 / K 11This enables LCDs (especially HB-FFS, FFS, and IPS mode LCDs) to have high brightness, high transmittance, and fast response time. In addition, a higher average elastic constant (K Avg. ), which results in a lower scattering parameter, which improves the dark state of the display and therefore improves the contrast.

[0045] In particular, the low temperature stability (LTS) of the medium according to the invention is very high. The medium is sufficiently stable at temperatures down to -40°C, so that the medium is particularly suitable for mobile applications, for example automotive applications.

[0046] The liquid-crystalline media according to the invention are suitable for mobile applications and TFT applications, for example mobile phones and PDAs. Furthermore, the liquid-crystalline media according to the invention are particularly suitable for use in FFS, HB-FFS and IPS displays based on dielectrically positive liquid crystals.

[0047] The liquid-crystalline media according to the invention are likewise suitable for liquid-crystalline displays in the FFS, HB-FFS and IPS modes based on dielectrically positive liquid crystals and polymer-stabilized variants thereof for large-format TV applications.

[0048] The invention also relates to the use of the liquid-crystalline media as described above and below 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-FF, positive VA and positive PS-VA displays, very preferably for FFS, HB-FFS, IPS, PS-HB-FFS and PS-IPS displays.

[0049] The invention further relates to an electro-optical liquid-crystal display containing a liquid-crystal medium as described above and below, 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 and positive PS-VA displays, preferably FFS, HB-FFS, IPS, PS-HB-FFS or PS-IPS displays.

[0050] In this context, alkyl and / or alkoxy are straight-chain or branched or cyclic alkyl radicals. They are preferably straight-chain, have 2, 3, 4, 5, 6 or 7 C atoms, and thus preferably represent ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy, furthermore methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy or tetradecyloxy.

[0051] In this context, the branched alkyl group is preferably isopropyl, sec-butyl, isobutyl, isopentyl, 2-methylbutyl, 2-methylhexyl or 2-ethylhexyl.

[0052] As used herein, cycloalkyl refers to straight-chain or branched alkyl or alkenyl radicals having up to 12 C atoms, preferably alkyl radicals having 1 to 7 C atoms, wherein the radical CH2 is replaced by a carbocyclic ring having 3 to 5 C atoms, very preferably selected from cyclopropylalkyl, cyclobutylalkyl, cyclopentylalkyl and cyclopentenylalkyl, wherein alkyl radical is a straight-chain alkyl radical having 1 to 5 C atoms.

[0053] In the present context, oxaalkyl preferably denotes straight-chain 2-oxapropyl (=methoxymethyl), 2-oxabutyl (=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanononyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl.

[0054] In this context, alkenyl, ie an alkyl radical 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 particularly denotes vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-enyl, oct-1-, -2-, -3-, -4-, -5-, -6- or -7-enyl, non-1-, -2-, -3-, -4-, -5-, -6-, -7- or -8-enyl, dec-1-, -2-, -3-, -4-, -5-, -6-, -7-, -8- or -9-enyl.

[0055] In this context, alkyl or alkenyl radicals which are at least monosubstituted by halogen are preferably straight-chain, halogen being preferably F or Cl. In the case of polysubstitution, halogen is preferably F. The resulting radicals also include perfluorinated radicals. In the case of monosubstitution, the fluorine or chlorine substituents may be in any desired position, but are preferably in the ω-position.

[0056] In this context, mono- or polyfluoroalkyl or alkoxy groups having 1, 2 or 3 C atoms, or mono- 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, OCC1FCF2CF3, OCH═CF2 or CH═CF2, very particularly preferably F or OCF3, furthermore CF3, OCF═CF2, OCHF2 or OCH═CF2.

[0057] Preferred compounds of formula I are selected from the following sub-formulae:

[0058]

[0059]

[0060]

[0061]

[0062]

[0063] where v is 1, 2, 3, 4, 5, or 6.

[0064] Very preferred compounds of the formula I are compounds I-1 to I-14.

[0065] In a preferred embodiment, the medium comprises one or more compounds of formula IA

[0066]

[0067] in

[0068] R 12 express wherein r is 0, 1, 2, 3, 4, 5 or 6, s is 1, 2 or 3, preferably 1, and the other radicals and parameters occurring have the meanings given above under formula I.

[0069] Preferred compounds of formula IA are compounds IA-1 to IA-14.

[0070]

[0071]

[0072] Preferably, the medium comprises one or more compounds of formula II, preferably selected from the compounds of formulae II-1 to II-3, very preferably selected from the compounds of formulae II-1 and II-3

[0073]

[0074] The radicals occurring therein have the respective meanings given above under formula II and formula II-1, the radical L 23 and L 24 represents H or F independently of each other and independently of other parameters, and in formula II-2 preferably

[0075] Independently express

[0076]

[0077] In formula II-1, II-2 and II-3, L 21 and L 22 or L 23 and L 24 Preferably, both are F.

[0078] In another preferred embodiment of formula II-1 and II-2, L 21 , L 22 , L 23 and L 24 Both represent F.

[0079] The compound of formula II-1 is preferably selected from the compounds of formula II-1a to II-1h

[0080]

[0081]

[0082] The radicals occurring therein have the respective meanings given above.

[0083] In a preferred embodiment of the present invention, the medium comprises one or more compounds selected from the group consisting of compounds of formulae II-1a to II-1h, wherein L 21 and L 22 and / or L 23 and L 24 Both are F.

[0084] In another preferred embodiment, the medium comprises a compound selected from the group consisting of compounds of formulae II-1a to II-1h, wherein L 21 , L 22 , L 23 and L 24 All are F.

[0085] Particularly preferred compounds of formula II-1 are

[0086]

[0087] Where R 2 has the meaning given above.

[0088] Preferably, the compound of formula II-2 is selected from compounds of formula II-2a to II-2c

[0089]

[0090]

[0091] The groups appearing therein have the above respective meanings, preferably L 21 and L 22 All are F. Preferably, the compound of formula II-3 is selected from the compounds of formula II-3a to II-3e

[0092]

[0093] The radicals occurring therein have the respective meanings given above, preferably L 21 and L 22 All are F, L 23 and L 24 Both are H, or

[0094] L 21 , L 22 , L 23 and L 24 All are F.

[0095] Particularly preferred compounds of formula II-3 are

[0096]

[0097] Where R 2 has the meaning given above.

[0098] In addition to the above preferred compounds of formula II, the medium optionally comprises one or more compounds of formula II selected from compounds of formulae IIA1 to IIA7:

[0099]

[0100]

[0101] Where R 2 and X 2 has the meanings given for formula II or one of the preferred meanings given above and below.

[0102] Preferred compounds are those of the formulae IIA1, IIA2 and IIA3, very preferably those of the formulae IIA1 and IIA2.

[0103] In the compounds of Formulae IIA1 to IIA7, R 2 Preferably denotes alkyl having 1 to 6 C atoms, very preferably ethyl or n-propyl, X 2 Preferably it represents F or OCF3, very preferably F.

[0104] In another preferred embodiment of the present invention, the medium comprises one or more compounds of formula III, which are preferably selected from formula III-1 and III-2, preferably formula III-2:

[0105]

[0106] The radicals and parameters occurring therein have the respective meanings given above under formula III.

[0107] R 3 Preferably it represents alkyl having 1 to 7 C atoms, or alkenyl having 2 to 7 C atoms.

[0108] Preferably, the compound of formula III-1 is selected from the compounds of formula III-1a and III-1b

[0109]

[0110] The radicals appearing therein have the respective meanings given above, L 33 and L 34 represents H or F independently of each other.

[0111] The compound of formula III-1a is preferably selected from the compounds of formula III-1a-1 to III-1a-6

[0112]

[0113]

[0114] Where R 3 has the meaning given above.

[0115] Preferably, the compound of formula III-2 is selected from the compounds of formula III-2a to III-2m

[0116]

[0117]

[0118]

[0119] The groups appearing therein have the above-mentioned respective meanings, L 35 and L 36 represents H or F independently of each other.

[0120] Preferably, the compound of formula II-2a is selected from the compounds of formula III-2a-1 to III-2a-4

[0121]

[0122]

[0123] Where R 3 has the meaning given above.

[0124] The compound of formula III-2b is preferably selected from the compounds of formula III-2b-1 and III-2b-2, preferably III-2b-2

[0125]

[0126] Where R 3 has the meaning given above.

[0127] The compound of formula II-2c is preferably selected from the compounds of formula III-2c-1 to III-2c-5

[0128]

[0129]

[0130] Where R 3 has the meaning given above.

[0131] The compounds of formula III-2d and III-2e are preferably selected from the compounds of formula III-2d-1 and III-2e-1

[0132]

[0133] Where R 3 Has the meanings stated above.

[0134] The compound of formula III-2f is preferably selected from the compounds of formula III-2f-1 to III-2f-7

[0135]

[0136]

[0137] Where R 3 has the meaning given above.

[0138] The compound of formula III-2g is preferably selected from the compounds of formula III-2g-1 to III-2g-7

[0139]

[0140]

[0141] Where R 3 Has the meanings stated above.

[0142] The compound of formula III-2h is preferably selected from the compounds of formula III-2h-1 to III-2h-5

[0143]

[0144] Where R 3 has the meaning given above.

[0145] The compound of formula III-2i is preferably selected from the compounds of formula III-2i-1 to III-2i-3

[0146]

[0147] Where R 3 has the meaning given above.

[0148] The compound of formula III-2j is preferably selected from the compounds of formula III-2j-1 to III-2j-3

[0149]

[0150] Where R 3 has the meaning given above.

[0151] The compound of formula III-2k is preferably selected from the compounds of formula III-2k-1 to III-2k-6

[0152]

[0153] Where R 3 has the meaning given above.

[0154] The compound of formula III-21 is preferably selected from the compounds of formula III-21-1 to III-21-6

[0155]

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

[0157] The compound of formula III-2m is preferably selected from the compound of formula III-2m-1

[0158]

[0159] Alternatively or in addition to the compounds of formula III-1 and / or III-2, the medium according to the invention optionally also comprises one or more compounds of formula III-3,

[0160]

[0161] wherein the radicals and parameters have the respective meanings given above under formula III,

[0162] Preferred Formula III-3a

[0163]

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

[0165] In addition to the preferred compounds of formula III above, the medium optionally comprises one or more compounds selected from formulae IIIA-1 to IIIA-21:

[0166]

[0167]

[0168]

[0169]

[0170] Where R 3 and X 3 has the meaning given for formula III or one of the preferred meanings given above and below. Preferred compounds are those of the formulae IIIA1, IIIA4, IIIA6, IIIA16, IIIA19 and IIIA20.

[0171] In the compounds of formulae IIIA1 to IIIA21, R 3 Preferably denotes alkyl having 1 to 6 C atoms, very preferably ethyl or propyl, X 3 Preferably it represents F or OCF3, very preferably F.

[0172] Preferably, the medium according to the invention comprises one or more compounds of formula IV

[0173]

[0174] in

[0175] 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, preferably a straight-chain alkenyl group having 2 to 12 C atoms,

[0176] R 12 represents straight-chain alkyl or alkoxy having 1 to 12 C atoms, or branched or cyclic alkyl or alkoxy having 3 to 12 C atoms, or straight-chain alkenyl having 2 to 12 C atoms, or branched alkenyl having 3 to 12 C atoms, or cyclic alkenyl having 5 to 12 C atoms, wherein one or more H atoms are optionally replaced by fluorine, preferably represents straight-chain alkyl having 1 to 12 C atoms, very preferably having 1 to 7 C atoms.

[0177] The compound of formula IV is preferably selected from the group consisting of the compounds of formulae IV-1 to IV-4, very preferably the compound of formula IV-3:

[0178]

[0179] in

[0180] Alkyl and alkyl' independently of one another denote an alkyl group having 1 to 7 C atoms, preferably having 2 to 5 C atoms,

[0181] alkoxy denotes an alkoxy group having 1 to 5 C atoms, preferably having 2 to 4 C atoms,

[0182] alkenyl denotes alkenyl having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 C atoms, and

[0183] Alkenyl′ denotes alkenyl having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms.

[0184] Preferably, the medium comprises one or more compounds of formula IV-1, preferably selected from compounds of formula IV-1-1 to IV-1-6

[0185]

[0186] Preferably, the medium according to the invention comprises one or more compounds of the formula IV-2-1 and / or IV-2-2

[0187]

[0188] Preferably, the medium according to the invention comprises a compound of the formula IV-3, very preferably selected from the compounds of the formulae IV-3-1 to IV-3-6, in particular compounds of the formulae IV-3-2 and / or IV-3-6:

[0189]

[0190]

[0191] Preferably, the medium according to the invention comprises a compound of the formula IV-4, in particular a compound selected from the group consisting of the formulae IV-4-1 and IV-4-2:

[0192]

[0193] Preferably, the medium according to the invention comprises one or more compounds of the formula IVa and / or IVb, very preferably IVb

[0194]

[0195] in

[0196] R 41 and R 42 each independently of one another represents a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkenyloxy radical having up to 12 C atoms, and

[0197] express

[0198] Z 4 It represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -C4H8- or -CF=CF-.

[0199] Preferred compounds of formula IVa are selected from compounds of formula IVa-1 to IVa-4:

[0200]

[0201] in

[0202] Alkyl and alkyl* each independently of one another denote a straight-chain alkyl radical having 1 to 6 C atoms.

[0203] The medium according to the invention preferably comprises at least one compound of the formula IVa-2.

[0204] Preferably, the compound of formula IVb is selected from the compounds of formula IVb-1 to IVb-3:

[0205]

[0206] in

[0207] Alkyl and alkyl* each independently represent a straight-chain alkyl radical having 1 to 6 C atoms, and

[0208] Alkenyl and alkenyl* each independently of one another represent straight-chain alkenyl having 2 to 6 C atoms.

[0209] Among the compounds of formulae IVb-1 to IVb-3, the compound of formula IVb-2 is particularly preferred.

[0210] Very particularly preferred compounds of the formula IVb are selected from the following compounds:

[0211]

[0212] The medium according to the invention particularly preferably comprises the compound IVb-2-3.

[0213] Preferably, the medium according to the invention comprises one or more compounds of the formula V

[0214]

[0215] in

[0216] 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,

[0217] Same or different

[0218]

[0219]

[0220] Z 51 , Z 52 each independently represents -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, and

[0221] n is 1 or 2.

[0222] The compound of formula V is preferably selected from the compounds of formulae V-1 to V-18:

[0223]

[0224]

[0225] Where R 51 and R 52 has the meaning indicated above for formula V.

[0226] R 51 and R 52 Preferably each independently of one another represents straight-chain alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms.

[0227] In a preferred embodiment of the invention, the medium additionally comprises one or more compounds of the formulae VI-1 to VI-9

[0228]

[0229]

[0230] in

[0231] R 6 Each independently has the R in claim 1 1 One of the meanings indicated, and

[0232] w each independently represents an integer of 1 to 6.

[0233] In a preferred embodiment of the invention, the medium additionally comprises one or more compounds of the formula VII,

[0234]

[0235] in

[0236] R 71 and R 72 represents H, F, a straight-chain alkyl or alkoxy radical having 1 to 15 C atoms, a straight-chain alkenyl or alkenyloxy radical having 2 to 15 C atoms, or a branched alkyl, alkoxy, alkenyl, alkenyloxy radical each having 3 to 15 C atoms, wherein one or more CH2 radicals in these radicals may each independently be -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, wherein one or more H atoms may be replaced by halogen,

[0237] X 71 To X 76 Identically or differently represent H or F, preferably, X 71 To X 76At least one of them represents F, more preferably X 71 To X 76 At least two of them represent F;

[0238] Z 71 and Z 72 Identically or differently represent CH2CH2 or a single bond.

[0239] The compound of formula VII is preferably selected from formula VII-1 and VII-2:

[0240]

[0241] The radicals occurring therein have the meanings given for formula VII.

[0242] The compound of formula VII-1 is preferably selected from the formulae VII-1-1 to VII-1-21, very preferably the formula VII-1-4:

[0243]

[0244]

[0245]

[0246] Where R 7 represents a straight-chain alkyl or alkoxy group having 1 to 6 C atoms, (O) represents -O- or a single bond, m is 0, 1, 2, 3, 4, 5 or 6, and n is 0, 1, 2, 3 or 4.

[0247] R 7 Preferably, it represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentyloxy.

[0248] In the compounds of formula VII-1-4, (O) preferably represents -O-.

[0249] The compound of formula VII-2 is preferably selected from the group consisting of formulae VII-2-1 to VII-2-15, very preferably formula VII-2-1:

[0250]

[0251]

[0252]

[0253] Where R 7 represents a straight-chain alkyl or alkoxy group having 1 to 6 C atoms, (O) represents -O- or a single bond, m is 0, 1, 2, 3, 4, 5 or 6, and n is 0, 1, 2, 3 or 4.

[0254] R7 Preferably, it represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentyloxy.

[0255] Preferably, the medium according to the invention comprises one or more compounds of formula VIII:

[0256]

[0257] in

[0258] R 81 and R 82 represents, identically or differently, 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 may each independently of one another be replaced by -CF2O-, -OCF2-, -CH=CH-, replaced by -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, wherein one or more H atoms may be replaced by halogen,

[0259] 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;

[0260] 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;

[0261] n represents 0, 1, 2 or 3, preferably 0, 1 or 2, very preferably 0 or 1, particularly preferably 0; and

[0262] m represents 0, 1, 2 or 3, preferably 0, 1 or 2, very preferably 1 or 2 and in particular 1.

[0263] wherein compounds of formula I are excluded from formula VIII.

[0264] A in Formula I 81 and A 82 Preferably it is phenylene-1,4-diyl, which may also be mono- or polysubstituted by F, furthermore cyclohexane-1,4-diyl, cyclohexenylene-1,4-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl, very preferably phenylene-1,4-diyl (which may also be mono- or polysubstituted by F), or cyclohexane-1,4-diyl.

[0265] Z in Formula I 81 and Z 82 It preferably represents -CF2O-, -OCF2- or a single bond, very preferably a single bond.

[0266] A in Formula I 81 and A 82 Particularly preferably,

[0267] Wherein L represents halogen, CF3 or CN, preferably F.

[0268] Furthermore, preferred are compounds of formula VIII, wherein R 81 and R 82 Each independently of one another represents H, F or alkyl, alkoxy, alkenyl or alkynyl having 1 to 8, preferably 1 to 5, C atoms, each of which is optionally substituted by halogen, in particular F.

[0269] R 81 and R 82 Preferably it represents H, optionally fluorinated alkyl or alkoxy having 1 to 7 C atoms, optionally fluorinated alkenyl or alkynyl having 2 to 7 C atoms, optionally fluorinated cycloalkyl having 3 to 12 C atoms.

[0270] Preferably, R 81 and R 82 At least one of them is not H, and R is particularly preferred 81 and R 82 Neither is H. R 81 Very particular preference is given to alkyl. 82 Further preferably, R 81 is an alkyl group, R 82is H or alkyl. 81 , R 82 each independently of one another very particularly preferably represents an unbranched alkyl radical having 1 to 5 C atoms. 81 and R 82 represents a substituted alkyl, alkoxy, alkenyl or alkynyl group, then R 81 and R 82 The total number of C atoms in both radicals is preferably less than 10.

[0271] Preferred compounds of formula VIII are selected from the following sub-formulae, more preferably selected from compounds of formula VIII-3:

[0272]

[0273] Where R 81 and R 82 has the meaning indicated above, L represents F, and 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 In particular, independently, it represents n-alkyl having 1 to 5 C atoms.

[0274] In a first very preferred embodiment, the compound of formula VIII-1 to VIII-6 is selected from the compounds of formula VIII-1a to VIII-6a, in particular the compound of formula VIII-3a:

[0275]

[0276]

[0277] Where R 81 , R 82 , L, r and s have the meanings defined above.

[0278] In a second very preferred embodiment, the compound of formula VIII-1 to VIII-6 is selected from the compounds of formula VIII-1b to VIII-5b, in particular the compound of formula VIII-2b:

[0279]

[0280]

[0281] Where R 1 , R 2 , L, r and s have the meanings defined above.

[0282] In a third very preferred embodiment, the compound of formula VIII-1 to VIII-6 is selected from the compounds of formula VIII-1c to VIII-6c, in particular the compound of formula I3-c:

[0283]

[0284] Where R 1 , R 2 , L, r and s have the meanings defined above.

[0285] In a fourth very preferred embodiment, the compound of formula VIII-1 to VIII-6 is selected from the compounds of formula VIII-1d to VIII-6d, in particular the compound of formula VIII-3d:

[0286]

[0287]

[0288] Where R 1 , R 2 , L, r and s have the meanings defined above.

[0289] In a particularly preferred embodiment, the medium according to the invention comprises one or more compounds selected from the formulae VIII-1a to VIII-6a and one or more compounds selected from the formulae VIII-1b to VIII-6b.

[0290] Very particularly preferably, the medium comprises one or more compounds selected from the group consisting of compounds of the formulae VIII-3a, VIII-2b, VIII-3c and VIII-3d:

[0291]

[0292]

[0293] Where R 81 , R 82 , L and r have the meanings defined above, preferably r is 0. The most preferred compounds of formula VIII particularly comprise one or more of the following:

[0294]

[0295]

[0296] Alternatively or additionally, the following compounds of formula VIII may be used:

[0297]

[0298]

[0299]

[0300] Preferably, the medium according to the invention comprises, in addition to the compound of formula I, one or more compounds having negative dielectric anisotropy, selected from the following formulae YA, YB, YC and YD, B, BA-1 and BA-2:

[0301]

[0302] in

[0303] R 2A , R 2B , R 2C and R 2D each independently of one another represents H, alkyl or alkenyl having up to 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 radicals may be replaced by -O-, -S-,

[0304] -CF2O-, -OCF2-, -OC-O- or -O-CO- are substituted in such a way that the O atoms are not directly connected to each other,

[0305] L 1 To L 4 each independently represents F, Cl, CF3 or CHF2,

[0306] Y represents H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, very preferably H,

[0307] 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-,

[0308] (O) represents O or a single bond,

[0309] p represents 0, 1 or 2,

[0310] q represents 0 or 1, and

[0311] v means 1, 2, 3, 4, 5, or 6,

[0312] wherein compounds of formula I are excluded from formula YD.

[0313] Preferred compounds of formula YA, YB, YC and YD are indicated below:

[0314]

[0315]

[0316]

[0317]

[0318]

[0319]

[0320]

[0321]

[0322]

[0323]

[0324] wherein the parameter a represents 1 or 2, alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl represents a straight-chain alkenyl group having 2 to 6 C atoms, and (O) represents an oxygen atom or a single bond. 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-.

[0325] Particularly preferred mixtures according to the invention comprise one or more compounds of the formulae YA-2, YA-8, YA-10, YA-16, YA-18, YA-40, YA-41, YA-42, YA-43, YB-2, YB-10, YB-16, YC-1, YD-4 and YD-10.

[0326] The proportion of compounds of the formulae YA and / or YB in the mixture as a whole is preferably at least 20% by weight.

[0327] Preferred media according to the invention comprise at least one compound of formula YC-1,

[0328]

[0329] wherein alkyl and alkyl* have the meanings indicated above, preferably in amounts of <5% by weight, in particular >3% by weight.

[0330] The medium according to the invention optionally comprises one or more compounds of the formula B

[0331]

[0332] in

[0333] R 11 and R 12 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 be replaced independently of one another

[0334] -CF2O-, -OCF2-, -CH=CH-, replaced by -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen,

[0335] A 1 In each occurrence, they are expressed independently of each other

[0336] a) 1,4-cyclohexenyl or 1,4-cyclohexylene, in which one or two non-adjacent CH2 groups may be replaced by -O- or -S-,

[0337] b) 1,4-phenylene, in which one or both CH groups may be replaced by N, or

[0338] 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,

[0339] wherein the groups a), b) and c) may be mono- or poly-substituted by halogen atoms,

[0340] n represents 0, 1 or 2, preferably 0 or 1,

[0341] 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, and

[0342] L 11 and L 12 each independently of one another represents F, Cl, CF3 or CHF2, preferably H or F, most preferably F, and

[0343] W represents O or S.

[0344] The compound of formula B is preferably selected from the compounds of formula B-1 and / or B-2

[0345]

[0346] The radicals occurring therein have the same meanings as given above under formula B and are preferably

[0347] R 11 and R 12 each independently of one another is alkyl, alkenyl or alkoxy having up to 15 C atoms, more preferably one or two of them represent alkoxy, and

[0348] L 11 and L 12 Each preferably represents F.

[0349] Preferably, the compound of formula B-1 is selected from the compounds of formula B-1-1 to B-1-11, preferably the compound of formula B-1-6,

[0350]

[0351]

[0352] in

[0353] 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, L 11 and L 12 Each independently represents F or Cl, preferably both are F.

[0354] Preferably, the compound of formula B-2 is selected from the compounds of formula B-2-1 to B-2-10, preferably the compound of formula B-2-6,

[0355]

[0356]

[0357] in

[0358] 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, L 1 and L 2 Each independently represents F or Cl, preferably both are F.

[0359] Optionally, the medium comprises one or more compounds of formula BA-1 and / or BA-2

[0360]

[0361] Where L 11 and L 12 has the same meaning as given under formula B, (O) represents O or a single bond,

[0362] R IIIA represents an alkyl or alkenyl group having up to 7 C atoms, or a group Cy-C m H 2m -,

[0363] m and n, identically or differently, are 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1,

[0364] Cy denotes a cycloaliphatic radical having 3, 4 or 5 ring atoms, which is optionally substituted by alkyl or alkenyl having in each case up to 3 C atoms, or by halogen or CN, and preferably denotes cyclopropyl, cyclobutyl or cyclopentyl.

[0365] The compounds of the formula BA-1 and / or BA-2 are contained in the medium as an alternative to or in addition to the compound of the formula B, preferably in addition.

[0366] Very preferred compounds of formula BA-1 and BA-2 are as follows:

[0367]

[0368]

[0369] wherein alkoxy represents a straight-chain alkoxy group having 1 to 6 C atoms, or alternatively -(CH2) n F (wherein n is 2, 3, 4 or 5), preferably C2H4F.

[0370] Alternatively, the medium comprises one or more compounds of the formula

[0371]

[0372] Here, alkenyl is a straight-chain alkenyl radical having 2 to 6 C atoms, preferably 4 C atoms, very preferably CH3-CH=CH-CH2-.

[0373] In a preferred embodiment of the present invention, the medium comprises one or more compounds of formula B-3

[0374]

[0375] in

[0376] R 11 , R 12 Identically or differently represent H, alkyl or alkoxy having 1 to 15 C atoms, wherein one or more CH2 groups in these radicals are optionally independently of one another -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, wherein in addition, one or more H atoms may be replaced by halogen. The compound of formula B-3 is preferably selected from the compounds of formulae B-3-1 to B-3-10:

[0377]

[0378]

[0379] Where R 12 represents alkyl having 1 to 7 C atoms, preferably ethyl, n-propyl or n-butyl, or alternatively represents cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl, or alternatively represents -(CH2) n F (wherein n is 2, 3, 4 or 5), preferably C2H4F.

[0380] In a preferred embodiment of the invention, the medium comprises one or more compounds of formulae B-4 to B-6, preferably a compound of formula B-5,

[0381]

[0382] The radicals occurring therein have the meanings given above, R 11 Preferably, it represents a straight chain alkyl group, R 12 Preferably denotes alkoxy, each having 1 to 7 C atoms.

[0383] In a preferred embodiment, the medium comprises one or more compounds of formula I selected from the group consisting of compounds of formulae B-7 to B-9, preferably B-8,

[0384]

[0385] where the parameters have the meanings given above, R 11 Preferably, it represents a straight chain alkyl group, R 12 Preference is given to alkoxy radicals which in each case have 1 to 7 C atoms.

[0386] In a preferred embodiment, the medium according to the invention comprises one or more HALS stabilizers of the formula H:

[0387]

[0388] in

[0389] Ar represents a methylene group or 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;

[0390] Sp represents a spacer group;

[0391] R S represents H, an alkyl group having 1 to 12 C atoms, or an alkenyl group having 2 to 12 C atoms;

[0392] Z S Indicates -O-, -C(O)O-, -(CH2) z -or-(CH2) z O-, or single bond;

[0393] HA means

[0394] R H Indicates H, O · , CH3, OH or OR S ;

[0395] R S1 , R S2 , R S3 and R S4 represent, identically or differently, alkyl having 1 to 6 C atoms, preferably having 1 to 3 C atoms, very preferably CH3;

[0396] G stands for H or R S or group Z S -HA;

[0397] z is an integer from 1 to 6, and

[0398] q is 2, 3 or 4, preferably 3 or 4;

[0399] The compound of formula I is preferably selected from the compounds of formula H-1, H-2 and H-3:

[0400]

[0401] Where R H has the meanings given above, preferably denotes H or O.,

[0402] Sp represents, at each occurrence, identically or differently, a spacer group, and

[0403] W represents a straight-chain or branched, optionally unsaturated alkylene radical having 1 to 12 C atoms, in which one or more non-adjacent -CH2- groups may be replaced by -O-.

[0404] Preferred compounds of formula H-1 are selected from compounds of formula H-1-1:

[0405]

[0406] Where R H has the above meanings, preferably denotes H or O., n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0407] Preferred compounds of formula H-2 are selected from compounds of formula H-2-1:

[0408]

[0409] Where R H has the meanings given above, preferably denotes H or O., n2 is, on each occurrence, identically or differently, preferably identically, an integer from 1 to 12, preferably 2, 3, 4, 5 or 6, very preferably 3, R S On each occurrence, identically or differently, preferably identically, represents alkyl having 1 to 6 C atoms, preferably n-butyl.

[0410] Preferred compounds of formula H-3 are selected from compounds of formula H-3-1:

[0411]

[0412] Where R H has the meaning given above, preferably represents H or O . , n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0413] Preferably, the medium according to the invention comprises a stabilizer selected from the compounds of formulae ST-1 to ST-19.

[0414]

[0415]

[0416]

[0417]

[0418]

[0419]

[0420] in

[0421] R ST represents H, alkyl or alkoxy having 1 to 15 C atoms, wherein in addition, one or more CH2 groups in these radicals may each independently of one another be -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O-, -O-CO- are substituted in such a way that the O atoms are not directly connected to one another, wherein in addition one or more H atoms may be replaced by halogen,

[0422] express

[0423]

[0424]

[0425] Z ST each independently represents -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-, -CH2O-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond,

[0426] L 1 and L 2 each independently represents F, Cl, CF3 or CHF2,

[0427] n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7,

[0428] n2, identically or differently, preferably identically, on each occurrence is an integer from 1 to 12, preferably 2, 3, 4, 5 or 6, very preferably 3, and

[0429] R S represents, identically or differently, preferably identically on each occurrence, alkyl having 1 to 6 C atoms, preferably n-butyl,

[0430] p means 1 or 2,

[0431] q represents 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0432] Among the compounds of formula ST, the compounds of formula

[0433]

[0434] wherein n=1, 2, 3, 4, 5, 6 or 7, preferably n=1 or 7

[0435]

[0436] wherein n=1, 2, 3, 4, 5, 6 or 7, preferably n=3

[0437]

[0438] wherein n=1, 2, 3, 4, 5, 6 or 7, preferably n=3

[0439]

[0440]

[0441]

[0442] In the compounds of formulae ST-3a and ST-3b, n preferably represents 3. In the compounds of formula ST-2a, n preferably represents 7.

[0443] Very particularly preferred mixtures according to the invention comprise one or more stabilizers selected from the group consisting of compounds of the formulae ST-2a-1, ST-3a-1, ST-3b-1, ST-8-1, ST-9-1 and ST-12:

[0444]

[0445]

[0446] The compounds of the 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 to 0.5%, based on the mixture.

[0447] If the mixtures according to the invention comprise two or more compounds of the formulae ST-1 to ST-19, in the case of two compounds the concentration is increased accordingly to 0.01 to 1%, based on the mixture.

[0448] However, the total proportion of compounds of the formulae ST-1 to ST-19, based on the mixture according to the invention, should not exceed 2%.

[0449] In another preferred embodiment of the present invention, the liquid-crystalline medium additionally comprises one or more polymerizable compounds. The polymerizable compounds are preferably selected from the group consisting of:

[0450] R a -B 1 -(Z b -B 2 ) m -R b M

[0451] In this context, the individual radicals have the following meanings, identically or differently and independently of one another, on each occurrence:

[0452] 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 radical having 1 to 25 C atoms, wherein in addition, one or more non-adjacent CH2 groups may each be replaced independently of one another by -C(R 0 )=C(R 00 )-、-C≡C-、-N(R 00 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and / or S atoms are not directly connected to each other, wherein in addition, one or more H atoms may be replaced by F, Cl, Br, I, CN, P or P-Sp-, wherein if B 1 and / or B 2 Contains saturated C atoms, R a and / or R b It can also represent a group connected to this saturated C atom spiro,

[0453] The group R a and R b At least one of them represents or contains a group P or P-Sp-,

[0454] P is a polymerizable group,

[0455] Sp is a spacer group or a single bond,

[0456] B 1 and B 2 is an aromatic, heteroaromatic, alicyclic or heterocyclic radical, preferably having 4 to 25 ring atoms, which may also contain fused rings, and which is unsubstituted or mono- or polysubstituted by L,

[0457] Z bis -O-, -S-, -CO-, -CO-O-, -OCO-, -O-CO-O-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -(CH2) n1 -, -CF2CH2-, -CH2CF2-, -(CF2) n1 -, -CH=CH-, -CF=CF-, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, CR 0 R 00 or single key,

[0458] R 0 and R 00 each independently of one another represents H or an alkyl radical having 1 to 12 C atoms,

[0459] M represents 0, 1, 2, 3 or 4,

[0460] n1 means 1, 2, 3 or 4,

[0461] L is P, P-Sp-, OH, CH2OH, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x )2, -C(=O)Y 1 、-C(=O)R x 、-N(R x )2, optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, wherein, among other things, one or more H atoms may be replaced by F, Cl, P or P-Sp-,

[0462] P and Sp have the meanings indicated above,

[0463] Y 1 represents halogen,

[0464] R x represents P, P-Sp-, H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein, in addition, one or more non-adjacent CH2 groups can be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and / or S atoms are not directly connected to one another, wherein, in addition, one or more H atoms can be replaced by F, Cl, P or P-Sp-, optionally substituted aryl or aryloxy having 6 to 40 C atoms or optionally substituted heteroaryl or heteroaryloxy having 2 to 40 C atoms.

[0465] Particularly preferred compounds of formula I are those wherein B 1 and B 2 each independently of one another represents 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl, naphthalene-2,6-diyl, phenanthrene-2,7-diyl, 9,10-dihydro-phenanthrene-2,7-diyl, anthracene-2,7-diyl, fluorene-2,7-diyl, coumarin, flavonoids, wherein in addition one or more CH groups in these radicals 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, all of which may be unsubstituted or mono- or poly-substituted by the above-mentioned L.

[0466] Particularly preferred compounds of formula M are those wherein B 1 and B 2 those which each independently of one another represent 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl,

[0467] Very preferred compounds of formula M are selected from the following formulae:

[0468]

[0469]

[0470]

[0471]

[0472] In this context, the individual radicals have the following meanings, identically or differently and independently of one another, on each occurrence:

[0473] P 1 , P 2 , P 3 is a polymerizable group, preferably selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy groups,

[0474] Sp 1 、Sp 2 、Sp 3 is a single bond or a spacer group, wherein in addition, the group P1 -Sp 1 -、P 1 -Sp 2 - and P 3 -Sp 3 -One or more of them can represent R aa , provided that the group P 1 -Sp 1 -、P 2 -Sp 2 and P 3 -Sp 3 - at least one of them is different from R aa , preferably represents -(CH2) p1 -、-(CH2) p1 -O-, -(CH2) p1 -CO-O- or -(CH2) p1 -O-CO-O-, wherein p1 is an integer from 1 to 12,

[0475] R aa is H, F, Cl, CN or a straight-chain or branched alkyl radical having 1 to 25 C atoms, wherein in addition, one or more non-adjacent CH2 groups may each independently be replaced by -C(R 0 )=C(R 00 )-、 -N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and / or S atoms are not directly connected to each other, and wherein in addition, one or more H atoms may be replaced by F, Cl, CN or P 1 -Sp 1 - alternatively, particularly preferably a straight-chain or branched, optionally monofluorinated or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy radical having 1 to 12 C atoms, where alkenyl and alkynyl have at least two C atoms and branched radicals have at least three C atoms,

[0476] R 0 , R 00 is H or an alkyl radical having 1 to 12 C atoms,

[0477] R y and R z is H, F, CH3 or CF3,

[0478] X 1 , X 2 , X 3 is -CO-O-, -O-CO- or a single bond,

[0479] Z M1 -O-, -CO-, -C(R y R z )-or-CF2CF2-

[0480] Z M2 , Z M3 -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -(CH2) n -, where n is 2, 3 or 4,

[0481] L is F, Cl, CN or linear or branched, optionally monofluorinated or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms,

[0482] L', L" are H, F or Cl,

[0483] r is 0, 1, 2, 3, or 4,

[0484] s is 0, 1, 2, or 3,

[0485] t is 0, 1, or 2,

[0486] x is either 0 or 1.

[0487] Especially preferred are compounds of formulae M2 and M13.

[0488] Further preference is given to the trireactive compounds M15 to M31, in particular M17, M18, M19, M22, M23, M24, M25, M30 and M31.

[0489] In the compounds of formulae M1 to M31, the group wherein L has one of the meanings given above, r represents 0, 1, 2, 3 or 4 radicals,

[0490] In particular, it indicates

[0491]

[0492] wherein L, at each occurrence, identically or differently, has one of the meanings given above or below, 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, in particular F or CH3.

[0493] Preferred compounds of formula M1 to M31 are those wherein P 1 , P 2 and P 3 Those representing acrylate, methacrylate, oxetane or epoxy groups, very preferably acrylate or methacrylate groups.

[0494] Further preferred compounds of formula M1 to M31 are those wherein Sp 1 、Sp 2 and Sp 3 Those that are single bonds.

[0495] Further preferred compounds of formula M1 to M31 are those wherein Sp 1 、Sp 2 and Sp 3 One of them is a single bond, and Sp 1 、Sp 2 and Sp 3 The other one in is different from those of single bonds.

[0496] Further preferred compounds of the formulae M1 to M31 are those in which the radical Sp which is different from a single bond is 1 、Sp 2 and Sp 3 Represents -(CH2) s1 -X"- compound, wherein s1 is an integer from 1 to 6, preferably 2, 3, 4 or 5, and X" is a linker to the benzene ring and is -O-, -O-CO-, -CO-O-, -O-CO-O- or a single bond.

[0497] Particular preference is given to liquid-crystalline media which comprise one, two or three polymerizable compounds of the formula M, preferably selected from the formulae M1 to M31.

[0498] It is further preferred that the liquid-crystalline media according to the invention comprise one or more polymerizable compounds selected from Table E below.

[0499] Preferably, the proportion of polymerizable compounds (preferably selected from the group consisting of formula M and table E) in the liquid-crystalline medium is from 0.01 to 5%, very preferably from 0.05 to 1%, most preferably from 0.1 to 0.5%.

[0500] It was observed that the addition of one or more polymerizable compounds, such as those selected from Formula M and Table E, to the liquid crystal medium resulted in advantageous properties, such as fast response time. Such liquid crystal media are particularly suitable for use in PSA displays, where they exhibit low image sticking, fast and complete polymerization, rapid development of stable low pretilt angles after UV exposure, high reliability, high VHR values ​​after UV exposure, and high birefringence. By appropriate selection of the polymerizable compound, the absorption of the liquid crystal medium at longer UV wavelengths can be increased, so that polymerization can be performed using such longer UV wavelengths, which is advantageous for the display manufacturing process.

[0501] The polymerizable group P is a group suitable for polymerization, such as free radical or ionic chain polymerization, addition polymerization or condensation polymerization, or for polymer analogous reactions, such as addition or condensation to the polymer backbone. Particularly preferred are groups for chain polymerization, in particular those containing a C=C double bond or a -C≡C- triple bond and groups suitable for ring-opening polymerization (e.g. oxetane or epoxy).

[0502] Preferred groups P are selected from CH2=CW 1 -CO-O-, CH2=CW 1 -CO-,

[0503]

[0504] CH2=CW 2 -(O) k3 -、CW 1 =CH-CO-(O) k3 -、CW 1 =CH-CO-NH-,

[0505] CH2=CW 1 -CO-NH-, CH3-CH=CH-O-, (CH2=CH)2CH-OCO-,

[0506] (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, HO-CW 2 W 3 -、HS-CW 2 W 3 -、HW 2 N-、HO-CW 2 W 3-NH-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -、CH2=CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH-, HOOC-, OCN- and W 4 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH3, W 2 and W 3 each independently of one another represents H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently represents Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W 7 and W 8 Each independently represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, which is optionally substituted by one or more groups L as described above, wherein the group L is not P-Sp-, k1, k2 and k3 each independently represent 0 or 1, k3 preferably represents 1, and k4 represents an integer from 1 to 10.

[0507] Very preferably the group P is selected from CH2=CW 1 -CO-O-, CH2=CW 1 -CO-,

[0508]

[0509] 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 alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH3, W 2 and W 3 each independently of one another represents H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently represents Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W 7 and W 8 Each independently represents H, Cl or an alkyl group having 1 to 5 C atoms. Phe represents 1,4-phenylene, k1, k2 and k3 each independently represent 0 or 1. k3 preferably represents 1, and k4 represents an integer of 1 to 10.

[0510] Very particularly preferred groups P 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-, as well as CH2=CH-O-, (CH2=CH)2CH-O-CO-, (CH2=CH)2CH-O-,

[0511] Further preferred polymerizable groups P are selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy groups, most preferably from acrylate and methacrylate groups.

[0512] If Sp is different from a single bond, it preferably has the formula Sp"-X", so that the corresponding group P-Sp- conforms to the formula P-Sp"-X"-, where

[0513] Sp" denotes an alkylene radical having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, wherein in addition, one or more non-adjacent CH2 groups may each independently of one another be substituted 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 the O and / or S atoms are not directly connected to each other,

[0514] X" means -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CO-N(R 0 )-、-N(R 0 )-CO-、-N(R 0 )-CO-N(R 00 )-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CR 0 -、-CY 2 =CY 3 -, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH- or a single bond,

[0515] R 0 and R 00 each independently of one another represents H or an alkyl group having 1 to 20 C atoms, and

[0516] Y 2 and Y 3 Each independently of one another represents H, F, Cl or CN.

[0517] X" is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -、-NR 0 -CO-、-NR 0 -CO-NR 00 - or single key.

[0518] 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 -, wherein p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, R 0 and R 00 has the meaning indicated above.

[0519] 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-, wherein p1 and q1 have the meanings indicated above.

[0520] Particularly preferred radicals Sp" are in each case linear ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethylene-N-methyliminoethylene, 1-methylalkylene, vinylene, propenylene and butenylene.

[0521] For the production of PSA displays, the polymerizable compounds contained in the LC medium are polymerized or crosslinked (if a compound contains two or more polymerizable groups) by in situ polymerization in the LC medium between the LC display substrates, optionally while applying a voltage to the electrodes.

[0522] The structure of the PSA display according to the invention corresponds to the usual geometries of PSA displays, as described in the prior art cited at the outset. Preference is given to geometries without protrusions, in particular those in which the electrodes on the color filter side are unstructured and only the electrodes on the TFT side have grooves. For example, a particularly suitable and preferred electrode structure for PS-VA displays is described in US 2006 / 0066793 A1.

[0523] The combination of the compounds of the abovementioned preferred embodiments with the abovementioned polymeric compounds leads to low threshold voltages, low rotational viscosities and very good low-temperature stability in the liquid-crystalline media according to the invention, with constantly high bright spots and high VHR values.

[0524] The use of liquid-crystalline media containing polymerizable compounds allows particularly low pretilt angles to be established quickly in PSA displays. In particular, in PSA displays, the liquid-crystalline media exhibit significantly shortened response times, in particular grayscale response times, compared with media from the prior art.

[0525] In a further preferred embodiment, the medium according to the invention comprises the following compounds, wherein the acronyms are explained in the following Table D:

[0526] - one, two or more compounds of formula I in a total concentration in the range of 0.5% to 10%, preferably 1% to 8%, particularly preferably 2% to 6%;

[0527] - one or more compounds of formula II, preferably compounds of formula II-1, more preferably compounds of sub-formula II-1a and / or II-1f and / or II-1g and / or III-1h, in particular compounds of formula II-1a-1 and / or II-1g-1, preferably in a total concentration in the range of 3% to 20%, preferably 5% to 18%, particularly preferably 7% to 15%;

[0528] and / or

[0529] - one or more compounds of formula III, in a total concentration in the range of 0.5% to 10%, preferably 1% to 8%, more preferably 1.5% to 7%, preferably selected from compounds of formula III-2, more preferably compounds of formula III-2c and / or III-2i and / or II-2l and / or II-2m, very preferably compounds of formula III-2c-4 and / or III-2i-3 and / or III-2l-3 and / or III-2m-1, in particular compounds of formula III-2l-3 and III-2m-1 and optionally III-2c-4, wherein the concentration of the compound(s) of formula III-2m-1 is very preferably 1% or less;

[0530] and / or

[0531] - one or more compounds of the formula YA, preferably compounds of the formula YA-2 and / or YA-10, in a total concentration in the range of 0.5% to 10%, preferably 1% to 7%, particularly preferably 2% to 5%;

[0532] and / or

[0533] - one or more compounds of the formula YB, preferably compounds of the formula YB-2 and / or YB-10, in a total concentration in the range of 0.5% to 10%, preferably 1% to 7%, particularly preferably 2% to 5%;

[0534] and / or

[0535] - one or more compounds of formula I and YA and optionally YB, preferably selected from the compounds of formula YA-2, YA-10, YB-2 and YB-10, in a total concentration in the range of 1% to 20%, preferably 2% to 15%, particularly preferably 3% to 12%;

[0536] - one or more compounds of formula IV-3, in a total concentration ranging from 40% to 70%, more preferably from 45% to 60%, very preferably selected from compounds of formulae IV-3-1 to IV-3-6, in particular compounds of formulae IV-3-1 and / or IV-3-2;

[0537] and / or

[0538] - 2% to 7%, preferably 3% to 6% of compound CC-3-2V1 or CC-4-V1, preferably compound CC-4-V1;

[0539] and / or

[0540] - one or more compounds of the formula IVb, preferably compounds of the formula VIb-2, very preferably compounds of the formula IVb-2-3, preferably in a total concentration in the range of 0.5% to 8%, more preferably 1% to 4%, in particular 2% to 3%;

[0541] and / or

[0542] One or more compounds of formula V, preferably selected from compounds V-11, V-12, V-13, V-14 and V-15; most preferably compounds of formula V-11 and / or V-14 and / or V-15, preferably in a total concentration in the range of 5% to 25%, preferably 8% to 20%, in particular 10% to 18%;

[0543] and / or

[0544] One or more compounds of formula VII, preferably compounds of formula VII-20 and / or VII-21, preferably in a total concentration ranging from 2% to 18%, preferably from 4% to 14%, in particular from 6% to 12%;

[0545] - a total of 10% to 30%, preferably 18% to 30%, more preferably 20% to 27% of one or more compounds of formulae V and VII.

[0546] The liquid crystal medium according to the invention allows a rotational viscosity γ1 of ≤80 mPa·s, particularly preferably ≤70 mPa·s, to be achieved while maintaining the nematic phase at a temperature as low as -20°C, preferably as low as -30°C, particularly preferably as low as -40°C, and a clearing point ≥75°C, preferably ≥79°C, so as to enable excellent MLC displays with fast response times. The rotational viscosity is measured at 20°C.

[0547] The dielectric anisotropy Δε of the liquid-crystal media according to the invention at 20° C. and 1 kHz is preferably ≧+1.5, preferably in the range from 1.5 to 8, more preferably from 2.0 to 6.0, very preferably from 2.5 to 4.5 and particularly preferably from 2.6 to 3.2.

[0548] The birefringence Δn of the liquid-crystalline media according to the invention at 20° C. is preferably from 0.095 to 0.110, very preferably from 0.098 to 0.105 and in particular from 0.100 to 0.102.

[0549] The rotational viscosity γ1 of the liquid-crystal medium according to the invention is preferably ≤100 mPa·s, more preferably ≤80 mPa·s and very preferably ≤70 mPa·s.

[0550] The γ1 / K1 ratio of the liquid-crystal medium according to the invention is preferably ≦5.5 mPa.s / pN.

[0551] In the present text, the structures of mesogenic compounds are indicated by abbreviations (also called acronyms). In these acronyms, the chemical formula is abbreviated as follows using the following Tables A to C. 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 = represents a straight-chain alkyl or alkylene radical, respectively, having in each case n, m or 1 C atoms, wherein n and m are independently 1, 2, 3, 4, 5, 6 or 7, and 1 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 the terminal groups. Table D shows illustrative structures of the compounds and their corresponding abbreviations.

[0552] Table A: Ring elements

[0553]

[0554]

[0555] Table B: Linking Groups

[0556]

[0557] Table C: End Groups

[0558]

[0559]

[0560] Use in combination with other

[0561]

[0562] wherein n and m each represent an integer, and the three dots "..." are placeholders for other abbreviations obtained from this table.

[0563] Table D

[0564]

[0565]

[0566]

[0567]

[0568]

[0569]

[0570]

[0571]

[0572]

[0573]

[0574]

[0575]

[0576]

[0577]

[0578]

[0579]

[0580]

[0581]

[0582]

[0583]

[0584]

[0585]

[0586]

[0587]

[0588]

[0589]

[0590] In a preferred embodiment of the invention, the medium comprises one or more compounds selected from the group consisting of compounds of Table D.

[0591] Table E shows chiral dopants which are preferably used in the mixtures according to the invention.

[0592] Table E

[0593]

[0594]

[0595]

[0596] Preferably, the medium according to the invention comprises one or more compounds chosen from the compounds of Table E.

[0597] Table F

[0598] Table F shows exemplary reactive mesogenic compounds (RM) which can be used in the LC media according to the present invention.

[0599]

[0600]

[0601]

[0602]

[0603]

[0604]

[0605]

[0606]

[0607]

[0608]

[0609]

[0610]

[0611]

[0612]

[0613]

[0614]

[0615]

[0616]

[0617]

[0618]

[0619] In a preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds, preferably selected from the group consisting of formulae RM-1 to RM-182. Among these, 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

[0620] Working Example:

[0621] The following examples are intended to illustrate the present invention without limiting it. In the examples, mp means melting point and T (N,I) Indicates 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, T g Indicates the glass transition temperature. The number between the two symbols indicates the transition temperature in degrees Celsius.

[0622] The main mixture used for determining the optical anisotropy Δn of the single compounds was the commercial mixture ZLI-4792 (Merck KGaA). The dielectric anisotropy Δε was determined using the commercial mixture ZLI-2857. The physical data for the compounds to be investigated were obtained from the change in the dielectric constant of the main mixture after adding the compound to be investigated and extrapolated to 100% of the compound used. In general, depending on the solubility, 10% of the compound to be investigated was dissolved in the main mixture.

[0623] Unless indicated otherwise, parts or percentages are parts or percentages by weight.

[0624] In the above and below:

[0625] V o represents the threshold voltage at 20°C, capacitance [V],

[0626] n e represents the extraordinary refractive index at 20°C and 589nm,

[0627] n o represents the ordinary refractive index at 20°C and 589nm,

[0628] Δn represents the optical anisotropy at 20°C and 589 nm,

[0629] ε ⊥ represents the dielectric permittivity perpendicular to the director at 20°C and 1kHz,

[0630] ε || represents the dielectric permittivity parallel to the director at 20°C and 1kHz,

[0631] Δε represents the dielectric anisotropy at 20°C and 1kHz,

[0632] cl.p.,T(N,I) represents the clearing point [℃],

[0633] γ1 represents the rotational viscosity [mPa·s] measured at 20°C,

[0634] K1 is the elastic constant, the "bending" deformation at 20°C [pN],

[0635] K2 represents the elastic constant, the "twist" deformation at 20°C [pN],

[0636] K3 represents the elastic constant, the "bending" deformation at 20°C [pN], and

[0637] LTS stands for low temperature stability (nematic phase) determined in a test cell or bulk as required.

[0638] Unless expressly stated otherwise, all temperature values ​​indicated in this application, such as melting point T(C,N), transition from smectic phase (S) to nematic phase (N) T(S,N) and clearing point T(N,I) or cl.p., are indicated in degrees Celsius (°C).

[0639] Unless explicitly indicated otherwise, the term "threshold voltage" used in the present invention relates to the capacitive threshold (V0), also known as the Freedericksz threshold. In the embodiments, typically, the optical threshold (V 10 ).

[0640] The display used to measure the capacitance threshold voltage consisted of two plane-parallel glass outer plates with a spacing of 20 μm, each with an electrode layer on the inside and an unrubbed polyimide alignment layer on top, which induces vertical edge alignment of the liquid crystal molecules.

[0641] The display or test cell used to measure the tilt angle consists of two plane-parallel glass outer plates with a spacing of 4 μm, each with an electrode layer on the inside and a polyimide alignment layer on top, where the two polyimide layers are rubbed antiparallel to each other and induce vertical edge alignment of the liquid crystal molecules.

[0642] The polymerizable compound is polymerized in the display or test cell by irradiating with UV light of defined intensity for a predetermined time while applying a voltage (typically 10V to 30V AC, 1kHz) to the display. In the examples, unless otherwise stated, a metal halide lamp and 100mW / cm 2 The intensity was used for polymerization. The intensity was measured using a standard instrument (a high-end Hoenle UV meter with a UV sensor).

[0643] The tilt angle is determined using a Mueller Matrix Polarimeter "AxoScan" from Axometrics. Here, low values ​​(ie large deviations from an angle of 90°) correspond to large tilts.

[0644] Unless otherwise stated, the term "tilt angle" means the angle between the LC director and the substrate, and "LC director" means the preferred orientation direction of the optical principal axes of the LC molecules in a layer of LC molecules with uniform orientation, which in the case of rod-shaped, uniaxially positively birefringent LC molecules corresponds to their molecular long axis.

[0645] Unless otherwise indicated, at 20°C (VHR 20 ) and after 5 minutes in an oven at 100°C (VHR 100) VHR was determined in a commercially available instrument model LCM-1 (00004) from TOYO Corporation, Japan. Unless indicated more specifically, the frequency of the voltage used was in the range of 1 Hz to 60 Hz.

[0646] The stability to UV irradiation was investigated in the commercially available instrument "Suntest CPS+" from Heraeus, Germany using a xenon lamp NXE1500B. Unless expressly indicated otherwise, the sealed test box was irradiated for 2.0 hours without additional heating. The irradiation power in the wavelength range from 300 nm to 800 nm was 765 W / m 2 V. UV "dielectric" filters with an edge wavelength of 310 nm were used in order to simulate the so-called window glass mode. In each series of experiments, at least four test boxes were investigated for each condition and the respective results are indicated as the average of the corresponding individual measurements.

[0647] The reduction in voltage holding ratio (ΔVHR) typically caused by light exposure (e.g. by UV irradiation or by LCD backlight) is determined according to the following equation (1):

[0648] △VHR(t)=VHR(t)-VHR(t=0) (1).

[0649] To study the low temperature stability (also called "LTS", i.e. the stability of LC mixtures in bulk against spontaneous crystallization of the individual components or the appearance of a smectic phase at low temperatures), several sealed bottles, each containing about 1 g of material, are stored at one or more given temperatures, typically -10°C, -20°C, -30°C and / or -40°C, as appropriate, and are visually checked regularly to see whether a phase transition is observed. As soon as the first sample at a given temperature shows a change, the test is stopped and the time until the last check, when no change is observed, is recorded as the respective LTS. The test is carried out for 1000 h. If there is no change after 1000 h, the result is "LTS>1000 h"

[0650] The resistivity was calculated from the ion density measured using a commercially available LC material characterization measurement system model 6254 from Toyo Corporation, Japan, using a VHR test cell of AL16301 polyimide (JSR Corp., Japan) with a cell gap of 3.2 μm. The measurements were performed after storage in an oven at 60°C or 100°C for 5 minutes.

[0651] By "HTP" is meant the helical twisting power (in μm) of an optically active or chiral substance in a LC medium. Unless otherwise indicated, HTP is measured at a temperature of 20°C in the commercially available nematic LC host mixture MLD-6260 (Merck KGaA).

[0652] The clearing point was measured using a Mettler Thermosystem FP900. The optical anisotropy (Δn) was measured using an Abbe-Refraktometer H005 (sodium spectrum lamp Na10 at 589 nm, 20°C). The dielectric anisotropy (Δε) was measured using an LCR-Meter E4980A / Agilent (G005) (ε parallel box with JALS2096-R1) at 20°C. The on-voltage (V0) was measured using an LCR-Meter E4980A / Agilent (G005) (ε parallel box with JALS2096-R1) at 20°C. The rotational viscosity (γ1) was measured using a TOYO LCM-2 (0002) (γ1 negative box with JALS-2096-R1) at 20°C. Elastic constant (K1, splay) was measured at 20°C using LCR-Meter E4980A / Agilent (G005) (ε parallel cell with JALS2096-R1). K3: Elastic constant (K3, bending) was measured at 20°C using LCR-Meter E4980A / Agilent (G005) (ε parallel cell with JALS2096-R1).

[0653] Unless otherwise expressly indicated, all concentrations in the present application are indicated as weight percent and relate to the entire corresponding mixture (without solvent) including all solid or liquid crystal components. Unless otherwise expressly indicated, all physical properties are 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.

[0654] The following examples of mixtures with negative dielectric anisotropy are particularly suitable for liquid crystal displays having at least one planar alignment layer, such as IPS and FFS displays, in particular UB-FFS (=Ultra Bright FFS) and VA displays.

[0655] Example

[0656] Comparative mixture C-1 and nematic mixtures M-1 to M-27 were prepared as follows:

[0657] Comparative mixture C1

[0658]

[0659] Mixture M1

[0660]

[0661] Mixture M2

[0662]

[0663]

[0664] The mixture according to the invention is characterized by an advantageously high K Avg. value and low γ1 / K1 value.

[0665]

[0666] Mixture M3

[0667]

[0668] Mixture M4

[0669]

[0670]

[0671] Mixture M5

[0672]

[0673] Mixture M6

[0674]

[0675] Mixture M7

[0676]

[0677]

[0678] Mixture M8

[0679]

[0680] Mixture M9

[0681]

[0682]

[0683] Mixture M10

[0684]

[0685] Mixture M11

[0686]

[0687]

[0688] Mixture M12

[0689]

[0690] Mixture M13

[0691]

[0692]

[0693] Mixture M14

[0694]

[0695] Mixture M15

[0696]

[0697] Mixture M16

[0698]

[0699]

[0700] Mixture M17

[0701]

[0702] Mixture M18

[0703]

[0704]

[0705] Mixture M19

[0706]

[0707] Mixture M20

[0708]

[0709] Mixture M21

[0710]

[0711]

[0712] Mixture M22

[0713]

[0714] Mixture M23

[0715]

[0716]

[0717] Mixture M24

[0718]

[0719] Mixture M25

[0720]

[0721]

[0722] Mixture M26

[0723]

[0724] Mixture M27

[0725]

[0726]

[0727] Mixture M28

[0728] Mixture M28 consists of 99.975% of mixture M1 and 250 ppm of stabilizer ST-3c

[0729]

[0730] Mixture M29

[0731] Mixture M29 consists of 99.975% of mixture M2, 150 ppm of stabilizer ST-3d and 100 ppm of stabilizer ST-19a

[0732]

Claims

1. A liquid crystal medium comprising a) one or more compounds of formula I in R 11 , R 12 Identically or differently represent straight-chain alkyl radicals having 1 to 12 C atoms or branched alkyl radicals having 3 to 12 C atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly connected to one another, wherein in addition one or more H atoms may be replaced by halogen, express Y 1 Indicates H or CH3, n1 is 0 or 1, v is 1, 2, 3, 4, 5, or 6; 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 straight-chain or branched alkyl or alkoxy radicals, which are unsubstituted or halogenated and have 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 liquid-crystalline medium according to claim 1 , wherein n1 is 1. 3 .

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 compounds of the formulae II-1, II-2 and II-3 in L 23 and L 24 represents H or F, and the remaining radicals have the meanings given in claim 1 under formula II.

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 and B. in Independently express R 11 , R 12 represents, identically or differently, straight-chain or branched alkyl or alkoxy, which is unsubstituted or halogenated and has 1 to 15 C atoms, wherein one or more CH2 groups in these radicals may 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, and R 12 Alternatively, F is represented by 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 Indicates -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, W means O or S, L 1 , L 2 , L 11 , L 12 identically or differently represent F or Cl, L 3 and L 4 , identically or differently represent H, F, Cl or CH3, Y represents H, F, Cl, CF3, CHF2 and CH3, and 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 radical having 1 to 15 C atoms, a straight-chain alkenyl or alkenyloxy radical having 2 to 15 C atoms, or a branched alkyl, alkoxy, alkenyl, alkenyloxy radical each having 3 to 15 C atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be -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 a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkenyloxy radical having up to 12 C atoms, express Z 4 Indicates 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, a straight-chain alkyl or alkoxy radical having 1 to 15 carbon atoms, a straight-chain alkenyl or alkenyloxy radical having 2 to 15 carbon atoms, or a branched alkyl, alkoxy, alkenyl or alkenyloxy radical having 3 to 15 carbon atoms, wherein one or more CH2 radicals in these radicals may each independently be replaced by -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 connected to each other, 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 . Liquid-crystalline medium according to one or more of claims 1 to 10 , wherein the medium additionally comprises one or more stabilizers.

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

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

14. Use of the liquid-crystalline medium according to one or more of claims 1 to 11 in liquid-crystalline displays.

15. Process for producing a liquid-crystalline medium according to one or more of claims 1 to 11, characterized in that One or more compounds of the formula I are mixed with one or more compounds of the formula II and / or III and optionally with one or more compounds of the formula B and / or Y.

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