Liquid crystal medium

Abstract

The invention relates to liquid-crystalline media, in particular based on mixtures of polar compounds, and to the use thereof for active matrix displays, in particular based on VA, SA-VA, IPS, PS-IPS, FFS, PS-FFS, UB-FFS or PS-UB-FFS effects.

Description

[0001] This application is a divisional application of the Chinese patent application with the application date of January 7, 2021, application number 202110016064.0, and invention name “Liquid Crystal Medium”. Technical Field

[0002] The present invention relates to liquid-crystalline media, in particular based on mixtures of polar compounds, and to their use in active-matrix displays, in particular based on the VA, SA-VA, IPS, PS-IPS, FFS, PS-FFS, UB-FFS or PS-UB-FFS effect. Background Art

[0003] Media of this type can be used in particular in electro-optical displays with active-matrix addressing based on the ECB effect and in IPS (in-plane switching) displays or FFS (fringe field switching) displays.

[0004] The principle of electrically controlled birefringence, the ECB effect or DAP (distortion of orientation phase) effect, was first described in 1971 (MF Schieckel and K. Fahrenschon, "Deformation of nematic liquid crystals with vertical orientation in electrical fields", Appl. Phys. Lett. 19 (1971), 3912). This was subsequently described in papers by JF Kahn (Appl. Phys. Lett. 20 (1972), 1193) and G. Labrunie and J. Robert (J. Appl. Phys. 44 (1973), 4869).

[0005] J. Robert and F. Clerc (SID 80 Digest Techn. Papers (1980), 30), J. Duchene (Displays 7 (1986), 3) and H. Schad (SID 82 Digest Techn. Papers (1982), 244) papers show that liquid crystal phases must have a high value of elastic constant ratio K3 / K1, a high value of optical anisotropy Δn and a dielectric anisotropy value of Δε≤-0.5 to be suitable for high information display elements based on the ECB effect. Electro-optical display elements based on the ECB effect have homeotropic edge alignment (VA technology = vertical alignment ). Dielectrically negative liquid-crystalline media can also be used in displays which use the so-called IPS or FFS effect.

[0006] In addition to IPS ( In-plane switching) displays (e.g., Yeo, SD, Paper 15.3: "An LC Display for the TV Application", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp. 758 & 759) and the long-known TN ( Twisted Nematic ) displays, displays using the ECB effect, such as in MVA ( Multi-domain vertical alignment , for example: Yoshide, H. et al., Paper 3.1: "MVA LCD for Notebook or Mobile PCs...", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book I, pp.6 to 9, and Liu, CT et al., Paper 15.1: "A 46-inch TFT-LCD HDTV Technology...", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp.750 to 753), PVA ( Patterned vertical alignment , for example: Kim, Sang Soo, paper 15.4: "Super PVA Sets New State-of-the-Art for LCD-TV", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp.760 to 763), ASV ( Advanced Super Vision horn , for example: Shigeta, Mitzuhiro and Fukuoka, Hirofumi, paper 15.2: "Development of HighQuality LCDTV", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp.754 to 757) mode in the so-called VAN ( Vertically aligned nematicThe display has established itself as one of the three newer types of liquid crystal displays that are most important today, especially for television applications. The technology is compared in general form, for example, in Souk, Jun, SID Seminar 2004, seminar M-6: "Recent Advances in LCD Technology", Seminar Lecture Notes, M-6 / 1 to M-6 / 26, and Miller, Ian, SID Seminar 2004, seminar M-7: "LCD-Television", Seminar Lecture Notes, M-7 / 1 to M-7 / 32. Although the response time of modern ECB displays has been significantly improved by addressing methods under overdrive, for example: Kim, Hyeon Kyeong et al., Paper 9.1: "A 57-in. Wide UXGA TFT-LCD for HDTV Application", SID2004 International Symposium, Digest of Technical Papers, XXXV, Book I, pp.106 to 109, obtaining video-compatible response times, especially grayscale switching, remains a problem that has not been satisfactorily resolved.

[0007] Industrial application of this effect in electro-optical display elements requires LC phases which must meet a variety of requirements. Of particular importance here is the chemical resistance to moisture, air and physical influences such as heat, infrared, visible and ultraviolet radiation as well as direct and alternating electric fields.

[0008] Furthermore, industrially useful LC phases need to have a liquid-crystalline mesophase in a suitable temperature range and with low viscosity.

[0009] None of the series of compounds disclosed so far having a liquid-crystalline mesophase comprises a single compound that meets all of these requirements. Therefore, mixtures of 2 to 25, preferably 3 to 18 compounds are usually prepared to obtain substances that can be used as LC phases. However, it has not been possible to easily prepare the optimal phase in this way, because there are currently no available liquid-crystalline materials with a significant negative dielectric anisotropy and suitable long-term stability.

[0010] Matrix liquid crystal displays (MLC displays) are known. Non-linear elements that can be used for single switching of individual pixels are, for example, active elements (ie transistors). Hence the term "active matrix" is used, wherein the following two types can be distinguished:

[0011] 1. MOS (metal oxide semiconductor) transistors located on a silicon wafer (as a substrate)

[0012] 2. Thin-film transistors (TFTs) located on a glass plate (as a substrate).

[0013] In the case of type 1, the electro-optical effect used is usually dynamic scattering or the guest-host effect. The use of single-crystal silicon as substrate material limits the display size, since even modular assembly of various component displays can create problems at the joints.

[0014] In the case of the preferred more promising type 2, the electro-optical effect used is generally the TN effect.

[0015] A distinction is made between two technologies: TFTs comprising compound semiconductors (eg CdSe), or TFTs based on polycrystalline or amorphous silicon. The latter technology is being intensively developed worldwide.

[0016] The TFT matrix is ​​applied to the inside of one glass plate of the display, while the other glass plate carries a transparent counter electrode on its inside. The TFTs are very small compared to the size of the pixel electrodes and have almost no adverse effect on the image. The technology can also be extended to full-color functional displays, where a mosaic of red, green and blue filters is arranged in such a way that a filter element is opposite each switchable pixel.

[0017] The term MLC display here covers any matrix display with integrated nonlinear elements, ie in addition to the active matrix, also displays with passive elements such as varistors or diodes (MIM=metal-insulator-metal).

[0018] MLC displays of this type are particularly suitable for TV applications (e.g. pocket TVs) or for high-information displays in automobile or aircraft construction. In addition to the problems with the angular dependence of the contrast and the response time, difficulties also arise in MLC displays due to the insufficiently high specific resistance of the liquid crystal mixture [TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K., TAJIMA, E., WATANABE, H., SHIMIZU, H., Proc. Eurodisplay 84, Sept. 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, pp. 141 ff., Paris; STROMER, M., Proc. Eurodisplay 84, Sept. 1984: Design of Thin Film Transistors for Matrix Addressing of Televis ion Liquid Crystal Displays, pp. 145 ff., Paris]. As the resistance decreases, the contrast of the MLC display deteriorates. The specific resistance of the liquid crystal mixture generally decreases over the lifetime of an MLC display due to interactions with the inner surfaces of the display, so a high (initial) resistance is very important for displays that must have acceptable resistance values ​​after long-term operation.

[0019] Therefore, there continues to be a great demand for MLC displays which have a very high specific resistance and at the same time a large operating temperature range, short response times and low threshold voltages, by means of which different gray scales can be produced.

[0020] Disadvantages of the frequently used MLC-TN displays are due to their relatively low contrast, the relatively high viewing angle dependence and the difficulty in producing grey scales in these displays.

[0021] VA displays have significantly better viewing angle dependence and are therefore mainly used in televisions and monitors. However, there is still a need to improve the response time, especially for use in televisions with frame rates (image change frequency / repetition rate) greater than 60 Hz. At the same time, however, properties such as low-temperature stability must not be impaired.

[0022] Mobile applications with high transmittance often use the UB-FFS mode. For additional power savings, low-frequency addressing is effectively used. However, this can lead to an undesirable effect known as flicker, which is a time-dependent brightness variation, i.e. the brightness fluctuates during the charging and holding period of the display operation. More precisely, flicker is defined as the difference in transmittance between positive and negative frames divided by the average transmittance. The lower the addressing frequency, the more noticeable it becomes.

[0023] The main causes of flicker include residual DC charge due to, for example, impurities, asymmetric voltage between electrodes or flexoelectric contribution in the FFS electrode structure layout. The flicker caused by the flexoelectric effect can be evaluated by the so-called white flicker method described in the Examples section.

[0024] Another problem is the occurrence of image sticking (or image burn-in), where the image produced by temporary addressing of individual pixels in an LC display remains visible even after the electric field in these pixels has been turned off or after other pixels have been addressed. This can be assessed by measuring the easy axis shift, which indicates the difference between the initial off-state orientation direction of the LC molecules relative to the substrate and their off-state orientation after several addressing cycles. Summary of the invention

[0025] The object of the present invention is to provide liquid-crystal mixtures, in particular for monitor and TV applications, which are based on the ECB effect or on the IPS effect or the FFS effect and which do not have the above-mentioned disadvantages or have them only to a reduced extent. In particular, for monitors and televisions it must be ensured that they operate at very high and very low temperatures and at the same time have short response times and at the same time have improved reliability behavior, in particular no or significantly reduced image sticking after long operating times and with reduced flicker.

[0026] This object is achieved by providing an LC medium as described and claimed below, wherein one or more compounds of formula B and / or C having negative dielectric anisotropy are used in combination with one or more compounds of formula G having terminal 3,4-difluorophenyl groups (hereinafter also referred to as "positive polarity compounds") having positive dielectric anisotropy. It has surprisingly been found that the LC medium according to the invention shows reduced flicker compared to LC media not comprising any positive polarity compounds or comprising different positive polarity compounds, while maintaining other desired properties, such as short response time, high transmittance and low threshold voltage.

[0027] The use of the LC mixtures disclosed and claimed below with negative dielectric anisotropy surprisingly leads to very low rotational viscosities and to a reduction in the ratio of rotational viscosity to elastic constants, while also maintaining high reliability and high VHR values ​​after UV exposure, and at the same time showing reduced flicker. It is thus possible to prepare liquid crystal mixtures, preferably VA, PS (= Polymer Stabilizer Stable )-VA, SA(= self-alignment )-VA, IPS, PS-IPS, PS-FFS, FFS mixture, especially UB-FFS (ultra-brightness fringe field switching) or PS-UB-FFS mixture. SUMMARY OF THE INVENTION

[0029] The present invention relates to liquid crystal (LC) media having negative dielectric anisotropy and comprising one or more compounds selected from the group consisting of formulae B and C and one or more compounds of formula G.

[0030]

[0031] where the individual radicals have the following meanings on each occurrence, identically or differently and independently of one another:

[0032] express

[0033] R 0 ,R 1 ,R 2 represents a straight-chain or branched alkyl or alkoxy radical having 1 to 15 carbon atoms, wherein in these radicals one or more CH2 groups 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, and wherein in addition one or more H atoms may be replaced by halogen, preferably by F,

[0034] L 1 , L 2 represents F or Cl, preferably F,

[0035] X 0 represents F, Cl, CN, SF5, SCN, NCS, a haloalkyl, haloalkenyl, haloalkoxy or haloalkenyloxy radical having up to 6 C atoms,

[0036] Y 1 Indicates O, S or CH2O,

[0037] Z0 It represents -C2H4-, -CH2O-, CF2O, -CH=CH- or a single bond.

[0038] The invention furthermore relates to the use of an LC medium as described above and below for electro-optical purposes, in particular in shutter glasses, for 3D applications or in VA, PS-VA, SA-VA, IPS, PS-IPS, FFS, PS-FFS, UB-FFS or PS-UB-FFS displays.

[0039] The invention furthermore relates to an electro-optical LC display, in particular a VA, PS-VA, SA-VA, IPS, PS-IPS, FFS, PS-FFS, UB-FFS or PS-UB-FFS display, comprising an LC medium as described above and below.

[0040] The invention furthermore relates to a process for preparing an LC medium as described above and below, which comprises the step of mixing one or more compounds selected from the formula B and / or formula C with one or more compounds of the formula G and optionally further LC compounds, and optionally one or more additives.

[0041] The LC media according to the invention preferably exhibit a very broad nematic phase range with a clearing point ≥70° C., preferably ≥74° C., very favorable values ​​for the capacitive threshold, relatively high retention values ​​and very good low-temperature stability at both −20° C. and −30° C., as well as very low rotational viscosities and short response times.

[0042] Furthermore, the LC media according to the invention are distinguished by the fact that, in addition to an improvement in the rotational viscosity γ1, high reliability and high VHR values ​​can be achieved even after UV exposure.

[0043] Furthermore, the LC media according to the invention are characterized by the fact that, in addition to an improvement in the rotational viscosity γ1, relatively high values ​​of the elastic constant K3 for an improved response time can also be observed. In particular, the mixtures according to the invention have particularly low values ​​of the ratio γ1 / K3 of the rotational viscosity γ1 and the elastic constant K3, which is an indication of a fast response time.

[0044] In the compounds of formula B, C and G, R 0 , R 1 and R 2 Preferably represents alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9, preferably 1 to 6, carbon atoms or alkenyl or alkenyloxy having 2 to 9, preferably 2 to 6, carbon atoms, all of which are optionally fluorinated, or a cycloalkyl ring having 3, 4 or 5 carbon atoms.

[0045] In the compounds of formula B and C, R 1 and R 2 Preferably it denotes an alkyl or alkoxy radical having 1 to 6 C atoms, which is preferably straight-chain.

[0046] Preferred compounds of formula B are selected from the following sub-formulae:

[0047]

[0048] Where R 1 and R 2 R has one of the meanings given in formula B and preferably represents straight-chain alkoxy having 1 to 6 carbon atoms, very preferably ethoxy, propoxy, butoxy, pentyloxy or hexyloxy. 1 Very preferably it represents ethoxy or propoxy, most preferably it represents propoxy. 2 Very preferably it represents ethoxy, propoxy, butoxy, pentyloxy or hexyloxy, most preferably butoxy, pentyloxy or hexyloxy.

[0049] Compounds of formula B2 are very preferred.

[0050] Very preferred compounds of formula B are selected from the following sub-formulae:

[0051]

[0052]

[0053] Preferred compounds of formula C are selected from the following sub-formulae:

[0054]

[0055] Where R 1 and R 2 has one of the meanings given in formula B. R 1 Preferably represents a straight-chain alkyl group having 1 to 6 carbon atoms, a cyclopentyl ring, a cyclopropyl ring, very preferably ethyl, propyl, butyl, pentyl or hexyl, most preferably ethyl, and R 2 Preferably it denotes straight-chain alkoxy having 1 to 6 carbon atoms, very preferably ethoxy, propoxy, butoxy, pentyloxy or hexyloxy, most preferably butoxy, pentyloxy or hexyloxy.

[0056] Compounds of formula C2 are very preferred.

[0057] Very preferred compounds of formula C are selected from the following sub-formulae:

[0058]

[0059]

[0060]

[0061] Preferably, the LC medium comprises one or more compounds selected from the group consisting of formulae B1, B2 and C2.

[0062] Preferably, the LC medium comprises 1, 2 or 3 compounds of the formulae B and / or C or subformulae thereof.

[0063] Very preferably, the LC medium comprises one or more compounds of the formula B2 and / or one or more compounds of the formula C2.

[0064] The total proportion of compounds of the formula B and its subformulae in the LC medium is preferably from 2 to 20% by weight, very preferably from 7 to 14% by weight.

[0065] The total proportion of compounds of the formula B1 and its subformulae in the LC medium is preferably from 2 to 8% by weight, very preferably from 3 to 5% by weight.

[0066] The total proportion of compounds of the formula B2 and its subformulae in the LC medium is preferably from 2 to 20% by weight, very preferably from 7 to 14% by weight.

[0067] The total proportion of compounds of the formula C and its subformulae in the LC medium is preferably from 2 to 20% by weight, very preferably from 8 to 12% by weight.

[0068] In the compound of formula G, R 0 Preferably it denotes alkyl having 1 to 6 C atoms or alkenyl having 2 to 6 C atoms, which is preferably straight-chain.

[0069] In the compound of formula G, X 0 Preferably it is F, Cl or a mono- or polyfluorinated alkyl or alkoxy radical having 1, 2 or 3 carbon atoms or a mono- or polyfluorinated alkenyl radical having 2 or 3 carbon atoms. 0 More preferably F, Cl, CF3, CHF2, OCF3, OCHF2, OCFHCF3, OCFHCHF2, OCFHCHF2, OCF2CH3, OCF2CHF2, OCF2CHF2, OCF2CF2CHF2, OCF2CF2CHF2, OCFHCF2CF3, OCFHCF2CHF2, OCF2CF2CF3, OCF2CF2CClF2, OCC1FCF2CF2CF3, OCH═CF2 or CH═CF2, very preferably F or OCF3, and CF3, OCF═CF2, OCHF2 or OCH═CF2, very particularly preferably F, OCF3 or CF3, most preferably F.

[0070] Preferred compounds of formula G are selected from the following sub-formulae:

[0071]

[0072] Where R 0 has one of the meanings given in formula G and preferably denotes straight-chain alkyl having 1 to 6 C atoms, very preferably ethyl, propyl or butyl, or straight-chain alkenyl having 2 to 6 C atoms, very preferably vinyl or 1-propenyl, most preferably vinyl, and X 0 has one of the meanings given in formula G and preferably denotes F, CF3 or OCF3, very preferably F.

[0073] Very preferred compounds of formula G are selected from the following sub-formulae:

[0074]

[0075]

[0076]

[0077]

[0078]

[0079] Preferably, the LC medium comprises one or more compounds selected from the group consisting of formulae G1-1, G1-3, G2-1 and G2-3.

[0080] Preferably, the LC medium comprises 1, 2 or 3 compounds of formula G or subformulae thereof.

[0081] The total proportion of compounds of the formula G and its subformulae in the LC medium is preferably from 2 to 20% by weight, very preferably from 4 to 10% by weight.

[0082] By using compounds of the formula B and / or C in combination with compounds of the formula G in the LC media according to the invention, one or more of the following advantages can be achieved:

[0083] -High transmittance,

[0084] - High contrast,

[0085] - Reduced image stickiness,

[0086] - Reduced ODF (one drop fill) non-uniformity (mura),

[0087] - High reliability and high VHR values ​​after UV exposure and / or heat treatment,

[0088] - high birefringence,

[0089] - reduced rotational viscosity,

[0090] - Faster response time,

[0091] - Reduced white flicker,

[0092] - Lower easy axis offset ΔΦ.

[0093] Further preferred embodiments of the LC media according to the invention, including any combinations thereof, are listed below:

[0094] a) The LC medium comprises one or more compounds of the formula CY and / or PY:

[0095]

[0096] in

[0097] a means 1 or 2,

[0098] b represents 0 or 1,

[0099] express

[0100] R 1 and R 2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein in addition, one or two non-adjacent CH2 groups may be independently of one another replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- 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 by F,

[0101] Preferred R 1 and R 2 represents an alkyl or alkoxy group having 1 to 6 C atoms,

[0102] Z x and Z y each independently represents -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,

[0103] L 1-4 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2, and

[0104] L 5 It represents H or CH3.

[0105] Preferably, L 1 and L 2 Both represent F or L 1 and L2 One of them represents F and the other represents Cl, or L 3 and L 4 Both represent F or L 3 and L 4 One of them represents F and the other represents Cl. 5 Preferably it represents H.

[0106] The compound of formula CY is preferably selected from the following sub-formulae:

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113]

[0114]

[0115]

[0116]

[0117] wherein a represents 1 or 2, alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, (O) represents an oxygen atom or a single bond, and alkenyl represents a straight-chain alkenyl group having 2 to 7 C atoms, and 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-.

[0118] The compound of formula PY is preferably selected from the following sub-formulae:

[0119]

[0120]

[0121]

[0122]

[0123]

[0124] wherein alkyl and alkyl* each independently of one another denote a straight-chain alkyl radical having 1 to 6 C atoms, (O) denotes an oxygen atom or a single bond, and alkenyl denotes a straight-chain alkenyl radical having 2 to 7 C atoms, and preferably denotes 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-. b) The LC medium comprises one or more compounds of the formula:

[0125]

[0126] Wherein, each group has the following meaning:

[0127] d means en means ot

[0128] express

[0129]

[0130] R 3 and R 4 Each independently has the same 1 the meanings given, and preferably denotes alkyl radicals having 1 to 12 C atoms, wherein, in addition, one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -O-CO- or -CO-O- in such a way that the O atoms are not directly connected to one another,

[0131] Z y It represents -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.

[0132] The compound of formula ZK is preferably selected from the following sub-formulae:

[0133]

[0134]

[0135] wherein alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl and alkenyl* each independently represent a straight-chain alkenyl group having 2 to 7 carbon atoms, and preferably represent CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0136] Compounds of the formulae ZK1, ZK2 and ZK3 are particularly preferred.

[0137] Very preferred compounds of formula ZK are selected from the following sub-formulae:

[0138]

[0139]

[0140] wherein m and n independently represent 1, 2, 3, 4, 5 or 6, i represents 0, 1, 2 or 3, and R b1 and R b2 Independently of each other, it represents H, CH3 or C2H5.

[0141] Particularly preferred compounds of formula ZK are selected from the following sub-formulae:

[0142]

[0143]

[0144] Among them, propyl, butyl and pentyl are straight chain groups.

[0145] Most preferred are compounds of formula ZK1a1, ZK2a1 and ZK2a6.

[0146] Preferably, the LC medium or LC host mixture comprises 1 to 5, preferably 1, 2 or 3 compounds selected from formula ZK or subformulae thereof.

[0147] The proportion of the compound of the formula ZK in the LC medium is preferably from 5 to 70%, more preferably from 10 to 60%, most preferably from 20 to 60%.

[0148] c) the LC medium comprises one or more compounds of the formula:

[0149]

[0150] Wherein, each radical has the following meanings identically or differently at each occurrence:

[0151] R5 and R 6 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein in addition, one or two non-adjacent CH2 groups may be independently of one another replaced by -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, preferably alkyl or alkoxy having 1 to 6 C atoms,

[0152] express

[0153]

[0154] d means en means ot

[0155] e represents 1 or 2.

[0156] The compound of formula DK is preferably selected from the following subformulae:

[0157]

[0158]

[0159] wherein alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl group having 2 to 7 C atoms, and 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-.

[0160] Compounds of formulae DK1 and DK3 are particularly preferred.

[0161] Very preferred compounds of formula DK are selected from the following sub-formulae:

[0162]

[0163] wherein m represents 1, 2, 3, 4, 5 or 6, i represents 0, 1, 2 or 3, and n represents 1, 2, 3, 4, 5 or 6.

[0164] Very particularly preferred compounds of the formula DK are selected from the following sub-formulae:

[0165]

[0166] d) the LC medium comprises one or more biphenyl compounds selected from the following formulae:

[0167]

[0168] wherein alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl and alkenyl* each independently represent a straight-chain alkenyl group having 2 to 6 C atoms. Alkenyl and alkenyl* preferably represent CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0169] The proportion of biphenyls of the formulae B-1 to B-3 in the LC mixture is preferably at least 3% by weight, in particular ≥5% by weight.

[0170] Compounds of formula B-2 are particularly preferred.

[0171] The compounds of formulae B-1 to B-3 are preferably selected from the following sub-formulae

[0172]

[0173]

[0174] Therein alkyl* denotes an alkyl radical having 1 to 6 carbon atoms. The medium according to the invention particularly preferably comprises one or more compounds of the formula B-1a and / or B-2c.

[0175] e) The LC medium comprises one or more compounds of the following formula DY:

[0176]

[0177] Wherein, each group has the following meaning:

[0178] express

[0179]

[0180] wherein at least one ring F is not cyclohexylene,

[0181] f means 1 or 2,

[0182] R 1 and R 2each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein, in addition, one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another,

[0183] Z x It represents -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.

[0184] L 1 and L 2 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2, and

[0185] L 3 It represents H or CH3.

[0186] Preferably, the group L 1 and L 2 Both represent F or group L 1 and L 2 One of them represents F and the other represents Cl. 3 Preferably it represents H.

[0187] The compound of formula DY is preferably selected from the following sub-formulae:

[0188]

[0189]

[0190]

[0191]

[0192] Among them, R 1 having the meanings indicated above, alkyl represents a straight-chain alkyl group having 1-6 C atoms, (O) represents an oxygen atom or a single bond, and v represents an integer from 1 to 6. 1 Preferably represents a straight-chain alkyl radical having 1 to 6 C atoms or a straight-chain alkenyl radical having 2 to 6 C atoms, in particular CH3, C2H5, n-C3H7, n-C4H9, n-C5H 11 , 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- or a cyclopentyl ring.

[0193] f) the LC medium comprises one or more compounds of the formula:

[0194]

[0195] where the individual radicals have the following meanings on each occurrence, identically or differently and independently of one another:

[0196] R 1 , R 2 As mentioned above for R 1 The meanings given here preferably denote alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms, or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated,

[0197] L T1 -L T6 represents H, F or Cl, where L T1 To L T6 At least one of is F or Cl,

[0198] The compound of formula T is preferably selected from the following sub-formulae:

[0199]

[0200]

[0201]

[0202] wherein R preferably represents a straight-chain alkyl or alkoxy group or a cyclopentyl ring having 1 to 7 C atoms, R* preferably represents a straight-chain alkenyl group having 2 to 7 C atoms, (O) represents an oxygen atom or a single bond, and m represents an integer from 1 to 6. R* 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-.

[0203] R and R* preferably represent methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentoxy.

[0204] Alkyl and alkyl* independently represent methyl, ethyl, propyl, butyl, pentyl and hexyl.

[0205] Alkenyl and alkenyl* independently represent CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0206] Very preferred are compounds of the formulae T1, T2, T21, T22 and T25.

[0207] Very preferred are compounds of the formula T1 in which (O) represents an oxygen atom, m is 1, 2, 3, 4 or 5, and R is methyl, ethyl, propyl, butyl, pentyl or hexyl, which is preferably linear.

[0208] Further preferred are compounds of the formula T2, in which (O) represents a single bond, m is 1, 2, 3, 4 or 5, and R is methyl, ethyl, propyl, butyl or pentyl or hexyl, which is preferably linear.

[0209] Preferably, the LC medium does not contain more than 15% of a compound of formula T or T1 to T25 or any other compound having a terphenyl group.

[0210] Preferably, the proportion of the compound of the formula T or T1 to T25 or any other compound having a terphenyl group in the LC medium is at least 5%, very preferably from 5 to 15%, most preferably from 5 to 10%.

[0211] Preferably, the LC medium contains 1 to 5, very preferably 1 or 2, compounds of the formula T or T1-T25.

[0212] g) the LC medium comprises one or more compounds selected from the following formulae:

[0213]

[0214]

[0215] Where alkyl represents C 1-6 -alkyl, L x represents H or F, and X represents F, Cl, OCF3, OCHF2 or OCH=CF2. Particularly preferred are compounds of formula G-1, wherein X represents F.

[0216] h) the LC medium comprises one or more compounds selected from the following formulae:

[0217]

[0218]

[0219] Among them, R5 With the above for R 1 One of the meanings indicated, alkyl means C 1-6 -alkyl, d represents 0 or 1, and z and m each independently represent an integer of 1 to 6. 5 C is particularly preferred 1-6 -alkyl or -alkoxy or C 2-6 -alkenyl, d is preferably 1. The LC media according to the invention preferably comprise one or more compounds of the abovementioned formulae in an amount of ≥5% by weight.

[0220] i) the LC medium comprises one or more compounds selected from the following formulae:

[0221]

[0222]

[0223] Among them, R 1 and R 2 has the meanings indicated above and preferably each independently of one another denotes straight-chain alkyl having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms.

[0224] Preferred media comprise one or more compounds selected from the group consisting of formula O1, O3, O4 and O-6.

[0225] Very particularly preferred embodiments are indicated below.

[0226] The medium according to the invention comprises at least three compounds selected from the group consisting of compounds of the following formulae:

[0227]

[0228]

[0229] The preferred amount is 8-50%.

[0230] The medium according to the invention comprises two compounds of the formula

[0231] The medium according to the invention comprises two compounds of the formula

[0232] Combined with one or more compounds of the formula

[0233] and / or

[0234]

[0235] and / or

[0236]

[0237] and / or

[0238]

[0239] Here, m represents an integer from 1 to 6.

[0240] k) The LC medium comprises one or more compounds of the formula:

[0241]

[0242] in

[0243] express

[0244]

[0245] R 9 represents H, CH3, C2H5 or n-C3H7, (F) represents an optional fluorine substituent, and q represents 1, 2 or 3, and R 7 With the above for R 1 Within the meaning indicated, preferably the amount is >3% by weight, in particular ≥5% by weight and very particularly preferably 5 to 30% by weight.

[0246] Particularly preferred compounds of formula FI are selected from the following sub-formulae:

[0247]

[0248]

[0249] Among them, R 7 Preferably represents a straight chain alkyl group, and R 9 represents CH3, C2H5 or n-C3H7. Particularly preferred are compounds of formula FI1, FI2 and FI3.

[0250] 1) The LC medium comprises one or more compounds selected from the following formulae:

[0251]

[0252] Among them, R 8 With respect to R 1 The meanings indicated, and alkyl denotes a straight-chain alkyl radical having 1 to 6 C atoms.

[0253] m) The LC medium comprises one or more compounds containing tetrahydronaphthyl or naphthyl units, for example compounds selected from the following formulae:

[0254]

[0255]

[0256]

[0257] in,

[0258] R 10 and R 11 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0259] and R 10 and R 11 preferably represents a straight-chain alkyl or alkoxy radical having 1 to 6 C atoms or a straight-chain alkenyl radical having 2 to 6 C atoms, and

[0260] Z 1 and Z 2 Each independently represents -C2H4-, -CH=CH-, -(CH2)4-, -(CH2)3O-, -O(CH2)3-, -CH=CH-CH2CH2-, -CH2CH2CH=CH-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CF=CH-, -CH=CF-, -CH2- or a single bond.

[0261] n) the LC medium comprises one or more difluorodibenzochromans and / or chromans of the formula:

[0262]

[0263] in,

[0264] R 11 and R 12 Each independently has the above for R 11 One of the meanings indicated, ring M is trans-1,4-cyclohexylene or 1,4-phenylene,

[0265] Z m is -C2H4-, -CH2O-, -OCH2-, -CO-O- or -O-CO-,

[0266] c is 0, 1 or 2, preferably in an amount of 3 to 20% by weight, especially in an amount of 3 to 15% by weight. Particularly preferred compounds of the formulae BC, CR and RC are selected from the following subformulae:

[0267]

[0268]

[0269]

[0270] wherein alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, (O) represents an oxygen atom or a single bond, c is 1 or 2, and alkenyl and alkenyl* each independently represent a straight-chain alkenyl group having 2 to 6 C atoms. Alkenyl and alkenyl* preferably represent CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0271] Very particular preference is given to mixtures comprising one, two or three compounds of the formula BC-2.

[0272] o) the LC medium comprises one or more fluorinated phenanthrenes of the formula:

[0273]

[0274] Among them, R 11 and R 12 Each independently has the above for R 11 means one of the indicated meanings, L means F, and r means 1, 2 or 3.

[0275] Particularly preferred compounds of formula PH are selected from the following sub-formulae:

[0276]

[0277] Here, R and R' each independently represent a straight-chain alkyl or alkoxy group having 1 to 7 C atoms.

[0278] p) the LC medium comprises one or more fluorinated dibenzofurans and / or dibenzothiophenes of the following formula:

[0279]

[0280] Wherein, each group has the following meaning:

[0281] express

[0282] R 11 and R 12 Each independently has the above for R 11One of the meanings pointed out is

[0283] Y 1 Indicates O or S,

[0284] L represents F, and

[0285] r represents 1, 2 or 3.

[0286] Particularly preferred compounds of formula BF are selected from the following sub-formulae:

[0287]

[0288] Wherein R and R' are each independently of each other and have the formula B R 1 The meaning of alkyl is preferably a straight-chain alkyl or alkoxy group having 1 to 7 carbon atoms.

[0289] q) The LC medium comprises one or more monocyclic compounds of the formula

[0290]

[0291] in,

[0292] R 1 and R 2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0293] L 1 and L 2 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2.

[0294] Preferably, L 1 and L 2 Both represent F or L 1 With L 2 One of them represents F and the other represents Cl,

[0295] The compound of formula Y is preferably selected from the following sub-formulae:

[0296]

[0297]

[0298] Wherein, Alkyl and Alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, Alkoxy represents a straight-chain alkoxy group having 1 to 6 C atoms, and Alkenyl and Alkenyl* each independently represent a straight-chain alkenyl group having 2 to 6 C atoms. Alkenyl and Alkenyl* preferably represent CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0299] Particularly preferred compounds of formula Y are selected from the following sub-formulae:

[0300]

[0301]

[0302] Here, Alkoxy preferably represents a straight-chain alkoxy group having 3, 4 or 5 C atoms, very preferably a butoxy group. Most preferred are compounds of the formula Y6A.

[0303] r) The LC medium contains 1 to 8, preferably 1 to 5, compounds of the formula CY and / or PY, preferably selected from the formulae CY1, CY2, CY9, CY10, CY41, CY43, CY45, PY1, PY2, PY9, PY10 and DY10, very preferably selected from the formulae CY1, CY2, CY9, CY10, PY9 and PY10. The proportion of these compounds in the overall mixture is preferably 5 to 60%, very preferably 10 to 50%. In a further preferred embodiment, the proportion of these compounds in the overall mixture is preferably 3 to 20%, very preferably 5 to 15%. The content of each individual compound is preferably 2 to 20%.

[0304] s) The LC medium contains 1 to 10, preferably 1 to 5, compounds of the formula ZK, preferably selected from the formulae ZK1, ZK2 and ZK3, very preferably selected from the formulae ZK1a1, ZK2a1, ZK2a2 and ZK3a1, most preferably selected from the formulae ZK1a1 to ZK1a6 and ZK2a1 to ZK2a7. The proportion of these compounds in the overall mixture is preferably 5 to 70%, more preferably 10 to 65%, most preferably 20 to 60%. The content of each individual compound is preferably 2 to 20%.

[0305] t) The LC medium contains 1 to 10, preferably 1 to 5, compounds of the formula DK, preferably selected from the formulae DK1 and DK3, more preferably from the formulae DK1a and DK3a, most preferably from the formulae DK3a1 and DK3a2. The proportion of these compounds in the overall mixture is preferably 1 to 20%, very preferably 2 to 15%. The content of each individual compound is preferably 1 to 5%.

[0306] u) The LC medium contains 1 to 5, preferably 1 or 2, compounds selected from the formulae B-1, B-2 and B-3, preferably selected from the formulae B-1 and B-2, more preferably selected from the formulae B-1a, B-2a, B-2c and B-2d. The proportion of these compounds in the overall mixture is preferably 1 to 10%, very preferably 1 to 5%. The content of each individual compound is preferably 1 to 5%.

[0307] v) The LC medium contains 1 to 5, preferably 1, 2 or 3, compounds of the formula T, preferably selected from the formulae T1, T2 and T23. The proportion of these compounds in the mixture as a whole is preferably 2 to 30%, very preferably 2 to 25. The content of each individual compound is preferably 2 to 15%.

[0308] w) The LC medium contains 1 to 3, preferably 1, compounds of the formula Y, preferably selected from the group consisting of the formula Y6, very preferably the formula Y6A. The proportion of these compounds in the mixture as a whole is preferably 2 to 20%, particularly preferably 3 to 15%.

[0309] x) the LC medium contains one or more compounds containing alkenyl groups, preferably selected from the formula CY, PY, DY and T, wherein R 1 and R 2 One or both represent a straight chain alkenyl group having 2 to 6 C atoms, formula ZK and DK, wherein R 3 and R 4 One or both or R 5 and R 6 One or both represent a straight-chain alkenyl group having 2 to 6 C atoms and the formulae B2 and B3, very preferably selected from the formulae CY3, CY4, CY15, CY24, CY32, PY7, PY8, PY15, PY16, DY13, ZK1, ZK2, ZK3, DK1, DK3, B2 and T23, most preferably selected from the formulae ZK1, ZK2, ZK3, DK1, DK3, B2 and T23. The concentration of these compounds in the LC host mixture is preferably 2 to 70%, very preferably 3 to 55%.

[0310] Particularly preferred mixture concepts are indicated below: (the abbreviations used are indicated in Table A. n and m here each independently of one another represent 1 to 6).

[0311] The mixture according to the invention preferably comprises

[0312] - CPY-n-Om, in particular CPY-2-O2, CPY-3-O2 and / or CPY-5-O2, preferably in a concentration of >5%, in particular 10-30%, based on the entire mixture,

[0313] and / or

[0314] -CY-n-Om, preferably CY-3-O2, CY-3-O4, CY-5-O2 and / or CY-5-O4, preferably in a concentration of >5%, in particular 15-50%, based on the entire mixture,

[0315] and / or

[0316] -CCY-n-Om, preferably CCY-4-O2, CCY-3-O2, CCY-3-O3 and / or CCY-5-O2, preferably in a concentration of >5%, in particular 10-30%, based on the entire mixture,

[0317] and / or

[0318] - CLY-n-Om, preferably CLY-2-O4, CLY-3-O2 and / or CLY-3-O3, preferably in a concentration of >5%, in particular 10-30%, based on the entire mixture,

[0319] and / or

[0320] - CK-nF, preferably CK-3-F, CK-4-F and / or CK-5-F, preferably in a concentration of > 5%, in particular 5-25%, based on the entire mixture,

[0321] The proportion of all mesogenic compounds in the liquid-crystal mixture according to the invention is ≤100%.

[0322] Furthermore, preference is given to mixtures according to the invention which comprise the following mixture concepts:

[0323] (n and m each independently represent 1 to 6.)

[0324] - CPY-n-Om and CY-n-Om, preferably in a concentration of 10-80%, based on the entire mixture, and / or

[0325] - CPY-n-Om and CK-nF, preferably in a concentration of 10-70%, based on the entire mixture, and / or

[0326] - CPY-n-Om and CK-nF and CLY-n-Om, preferably in a concentration of 10 to 80%, based on the entire mixture, wherein the proportion of all mesogenic compounds in the liquid-crystal mixture according to the invention is ≤100%.

[0327] The combination of the compounds of the abovementioned preferred embodiments with the abovementioned polymeric compounds leads in the LC media according to the invention to low threshold voltages, low rotational viscosities and very good low-temperature stability with simultaneously constantly high clearing points and high VHR values.

[0328] The use of LC media containing polymerizable compounds allows particularly low pretilt angles to be quickly established in PSA displays. In particular, the LC media exhibit significantly shortened response times in PSA displays, in particular also gray-to-gray response times, compared with media from the prior art.

[0329] The LC media and LC host mixtures according to the invention preferably have a nematic phase range of at least 80 K, particularly preferably at least 100 K, and a rotational viscosity at 20° C. of ≤150 mPa·s, preferably ≤100 mPa·s.

[0330] In a VA type display according to the invention, the molecules in the layer of the LC medium in the off state are aligned perpendicular to the electrode surface (homeotropically) or have a tilted homeotropic alignment. When a voltage is applied to the electrodes, a realignment of the LC molecules occurs with the longitudinal molecular axes parallel to the electrode surface.

[0331] The LC media according to the invention are preferably based on compounds having negative dielectric anisotropy and are particularly suitable for use in displays of the VA, UB-FFS, PS-VA and PS-UB-FFS type and preferably have a negative dielectric anisotropy Δε at 20° C. and 1 kHz, very preferably from −0.5 to −10 and most preferably from −2.0 to −7.5.

[0332] The birefringence Δn in the LC media according to the invention, in particular for use in displays of the VA, UB-FFS, PS-VA and PS-UB-FFS type, is preferably below 0.16, particularly preferably from 0.06 to 0.14, very particularly preferably from 0.07 to 0.13.

[0333] The LC media according to the invention may also comprise further additives known to the person skilled in the art and described in the literature, such as polymerization initiators, inhibitors, stabilizers, surface-active substances or chiral dopants. These may be polymerizable or non-polymerizable.

[0334] In a preferred embodiment of the present invention, the LC medium additionally comprises one or more polymerisable compounds.

[0335] The polymerizable compound is preferably selected from the group consisting of formula M

[0336] R a -B 1 -(Z b -B 2 ) m -Rb M

[0337] In this context, the individual radicals have the following meanings, identically or differently on each occurrence and independently of one another:

[0338] 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, and 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, then R a and / or R b It can also represent a group connected to the saturated C atom in a spirocyclic manner,

[0339] Among them, the group R a and R b at least one of which represents or contains a group P or P-Sp-,

[0340] P is a polymerizable group,

[0341] Sp is a spacer group or a single bond,

[0342] 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,

[0343] 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 single key,

[0344] R 0 and R 00 each independently of one another represents H or an alkyl radical having 1 to 12 C atoms,

[0345] m represents 0, 1, 2, 3 or 4,

[0346] n1 means 1, 2, 3 or 4,

[0347] L represents 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 in addition one or more H atoms may be replaced by F, Cl, P or P-Sp-,

[0348] P and Sp have the meanings indicated above,

[0349] Y 1 represents halogen,

[0350] 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, and 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.

[0351] Particularly preferred compounds of formula I are those wherein B 1 and B 2each 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 polysubstituted by L as defined above.

[0352] 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.

[0353] Very preferred compounds of formula M are selected from the following formulae:

[0354]

[0355]

[0356]

[0357]

[0358] In this context, the individual radicals have the following meanings, identically or differently on each occurrence and independently of one another:

[0359] P 1 , P 2 , P 3 is a polymerizable group, preferably selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy,

[0360] Sp 1 、Sp 2 、Sp 3 is a single bond or a spacer group, wherein in addition, the group P 1 -Sp 1 -、P 1 -Sp 2 - and P 3 -Sp3 -One or more of R aa , provided that the group P 1 -Sp 1 -、P 2 -Sp 2 and P 3 -Sp 3 - at least one of which 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,

[0361] 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 )-、-C≡C-、-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 linear 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,

[0362] R 0 , R 00 is H or an alkyl radical having 1 to 12 C atoms,

[0363] R y and R z is H, F, CH3 or CF3,

[0364] Z M1 -O-, -CO-, -C(R y R z )- or -CF2CF2-,

[0365] Z M2 , Z M3 -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -(CH2)n -, where n is 2, 3 or 4,

[0366] L is F, Cl, CN or a linear or branched, optionally monofluorinated or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy radical having 1 to 12 C atoms,

[0367] L', L" are H, F or Cl,

[0368] k is 0 or 1,

[0369] r is 0, 1, 2, 3, or 4,

[0370] s is 0, 1, 2, or 3,

[0371] t is 0, 1, or 2,

[0372] x is 0 or 1.

[0373] Particularly preferred are compounds of the formulae M2 and M13.

[0374] Additionally preferred are the trireactive compounds M15 to M31, in particular M17, M18, M19, M22, M23, M24, M25, M30, M31 and M32.

[0375] In the compounds of formulae M1 to M32, the group

[0376] Preferably

[0377]

[0378] In this case, L has, identically or differently on each occurrence, 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 and in particular F or CH3.

[0379] Preferred compounds of formula M1 to M32 are those wherein P 1 , P 2 and P 3 Those representing acrylate, methacrylate, oxetane or epoxy groups, very preferably acrylate or methacrylate groups.

[0380] Further preferred compounds of formulae M1 to M32 are those wherein Sp 1 、Sp 2 and Sp 3 Those that are single bonds.

[0381] Further preferred compounds of formulae M1 to M32 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 ones are not single bond ones.

[0382] Further preferred compounds of the formulae M1 to M32 are those in which the radical Sp is not a single bond 1 、Sp 2 and Sp 3 Represents -(CH2) s1 -X"-, 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.

[0383] Particularly preferred are LC media comprising one, two or three polymerisable compounds of the formula M, preferably selected from the formulae M1 to M32.

[0384] Additional preferred polymerizable compounds are listed in Table D below.

[0385] Preferably, the proportion of polymerizable compounds in the LC medium is from 0.01 to 5%, very preferably from 0.05 to 1%, most preferably from 0.1 to 0.5%.

[0386] The polymerizable group P is a group suitable for polymerization, such as free radical or ionic chain polymerization, addition polymerization or polycondensation or for analogous polymer reactions, such as addition or condensation to the main polymer chain. Particularly preferred are groups for chain polymerization, especially those containing a C=C double bond or a -C≡C- triple bond, and groups suitable for ring-opening polymerization, such as oxetane or epoxide groups.

[0387] Preferred groups P are selected from CH2=CW 1 -CO-O-, CH2=CW 1 -CO-, CH2=CW 2 -(O) k3 -、CW 1 =CH-CO-(O) k3 -、CW 1=CH-CO-NH-, CH2=CW 1 -CO-NH-, CH3-CH=CH-O-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, HO-CW 2 W 3 -、HS-CW 2 W 3 -、HW 2 N-、HO-CW 2 W 3 -NH-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -、CH2=CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH-, HOOC-, OCN- and W 4 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF3, phenyl or 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, oxacarbonylalkyl or oxaalkyl having 1 to 5 C atoms, W 7 and W 8 Each independently of one another represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene which is optionally substituted by one or more groups L as defined above which are not 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 to 10.

[0388] Very preferably the group P is selected from CH2=CW 1 -CO-O-, CH2=CW 1 -CO-, CH2=CW 2 -O-, CH2=CW 2 -、CW 1 =CH-CO-(O) k3 -、CW1 =CH-CO-NH-, CH2=CW 1 -CO-NH-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -、CH2=CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH- and W 4 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF3, phenyl or 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, oxacarbonylalkyl or oxaalkyl 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.

[0389] Very particularly preferred groups P are selected from the group consisting of CH2=CW 1 -CO-O-, especially CH2=CH-CO-O-, CH2=C(CH3)-CO-O- and CH2=CF-CO-O-, in addition CH2=CH-O-, (CH2=CH)2CH-O-CO-, (CH2=CH)2CH-O-,

[0390] Further preferred polymerizable groups P are selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, most preferably acrylate and methacrylate.

[0391] If Sp is not a single bond, it preferably has the formula Sp"-X", so that each group P-Sp- conforms to the formula P-Sp"-X"-, where

[0392] 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, and 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,

[0393] 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,

[0394] R 0 and R 00 each independently of one another represents H or an alkyl group having 1 to 20 C atoms, and

[0395] Y 2 and Y 3 each independently represents H, F, Cl or CN,

[0396] X" is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -、-NR 0 -CO-、-NR 0 -CO-NR 00 - or single key.

[0397] 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, and R 0 and R 00 has the meaning indicated above.

[0398] 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.

[0399] 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.

[0400] To produce a PSA or PS-VA display, the polymerisable compounds contained in the LC medium are polymerised or crosslinked (if one compound contains two or more polymerisable groups) in the LC medium between the substrates of the LC display by in situ polymerisation, optionally while applying a voltage to the electrodes.

[0401] The structure of the PSA display according to the invention corresponds to the usual geometrical construction of PSA displays, as described in the prior art cited at the outset. Geometrical constructions without protrusions are preferred, in particular those in which the electrodes on the color filter side are also unstructured and only the electrodes on the TFT side have grooves. Particularly suitable and preferred electrode structures for PS-VA displays are described, for example, in US 2006 / 0066793 A1.

[0402] Preferably, the proportion of polymerizable compounds in the LC medium is >0 to <5%, very preferably >0 to <1%, most preferably 0.01 to 0.5%.

[0403] Optionally, one or more polymerization initiators are added to the LC medium. Suitable polymerization conditions and suitable initiator types and amounts are known to the person skilled in the art and are described in the literature. Suitable for free-radical polymerization are, for example, commercially available photoinitiators or (Ciba AG). If a polymerization initiator is used, its proportion is preferably from 0.001 to 5% by weight, particularly preferably from 0.001 to 1% by weight.

[0404] In a further preferred embodiment, the LC medium contains no polymerisation initiator.

[0405] The LC medium may also contain one or more stabilizers. Suitable stabilizer types and amounts are known to the person skilled in the art and are described in the literature. Particularly suitable are, for example, Commercially available stabilizers of the TUNA series (Ciba AG), for example 1076. If stabilizers are used, their proportion is preferably 10-500,000 ppm, more preferably 50-5,000 ppm, very preferably 50-1,000 ppm.

[0406] In another preferred embodiment of the present invention, the LC medium contains one or more stabilizers selected from Table C below.

[0407] In another preferred embodiment of the present invention, the LC medium contains one or more stabilizers selected from the following formulae

[0408]

[0409] In this context, the individual radicals independently of one another and identically or differently on each occurrence have the following meanings

[0410] R a-d is a straight-chain or branched alkyl radical having 1 to 10, preferably 1 to 6, very preferably 1 to 4 C atoms, most preferably methyl,

[0411] X S H, CH3, OH or O ● ,

[0412] A S is a linear, branched or cyclic alkylene radical having 1 to 20 C atoms, which is optionally substituted,

[0413] n is an integer of 1 to 6, preferably 3.

[0414] Preferred stabilizers of formula S3 are selected from formula S3A

[0415]

[0416] wherein n2 is an integer from 1 to 12, and wherein the group (CH2) n2 One or more H atoms in are optionally replaced by methyl, ethyl, propyl, butyl, pentyl or hexyl.

[0417] Very preferred stabilizers are selected from the following formula

[0418]

[0419]

[0420]

[0421] In a preferred embodiment, the liquid-crystalline medium comprises one or more stabilizers selected from the group consisting of formulae S1-1, S2-1, S3-1, S3-1 and S3-3.

[0422] In a preferred embodiment, the liquid-crystalline medium comprises one or more stabilizers selected from Table C below.

[0423] Preferably, the proportion of stabilizers, such as those of the formulae S1 to S3, in the liquid-crystalline medium is from 10 to 500 ppm, very preferably from 20 to 100 ppm.

[0424] In another preferred embodiment, the LC media according to the invention contain one or more SA additives selected from formula II or its subformulae. The concentration of the SA additive in the LC medium is preferably from 0.1 to 5%, very preferably from 0.2 to 3%, most preferably from 0.2 to 1.5%.

[0425] In a preferred embodiment, the LC media or displays according to the invention contain one or more SA additives selected from Table F below.

[0426] In a further preferred embodiment, the SA-VA or SA-FFS display according to the invention contains no polyamide alignment layer.

[0427] Preference is given to LC media which have a nematic LC phase and preferably no chiral liquid crystal phase.

[0428] In another preferred embodiment, the LC medium contains one or more chiral dopants, preferably in a concentration of 0.01 to 1%, very preferably 0.05 to 0.5%. The chiral dopant is preferably selected from the compounds from Table B below, very preferably selected from R- or S-1011, R- or S-2011, R- or S-3011, R- or S-4011 and R- or S-5011.

[0429] In a further preferred embodiment, the LC medium contains the racemate of one or more chiral dopants, which are preferably selected from the chiral dopants mentioned in the previous paragraph.

[0430] Furthermore, it is possible to add, for example, 0 to 15% by weight of pleochroic dyes to the LC medium, and also nanoparticles, conductive salts, preferably ethyldimethyldodecylammonium 4-hexyloxybenzoate, tetrabutylammonium tetraphenylborate or complex salts of crown ethers (see, for example, Haller et al., Mol. Cryst. Liq. Cryst. 24 , 249-258 (1973)), to improve the conductivity, or to add substances for changing the dielectric anisotropy, viscosity and / or orientation of the nematic phase. Substances of this type are described, for example, in DE-A 2209 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 28 53 728.

[0431] The individual components of the preferred embodiments a) to z) of the LC media according to the invention are known or their preparation can be easily derived from the prior art by a person skilled in the art, since they are based on standard methods described in the literature. The corresponding compounds of the formula CY are described, for example, in EP-A-0 364 538. The corresponding compounds of the formula ZK are described, for example, in DE-A-26 36684 and DE-A-33 21 373.

[0432] The LC media which can be used according to the invention are prepared in a manner conventional per se, for example by mixing one or more of the abovementioned compounds with one or more polymerizable compounds as defined above and optionally with further liquid-crystalline compounds and / or additives. Usually, the required amount of the component used in smaller amounts is dissolved in the component constituting the main constituents, advantageously at elevated temperature. It is also possible to mix the solutions of the components in an organic solvent, for example acetone, chloroform or methanol, and to remove the solvent again after thorough mixing, for example by distillation. The invention furthermore relates to a process for preparing the LC media according to the invention.

[0433] It goes without saying to the person skilled in the art that the LC media according to the invention may also comprise compounds in which, for example, H, N, O, Cl, F have been replaced by corresponding isotopes, such as deuterium or the like.

[0434] The construction of the LC display according to the invention consisting of polarizer, electrode substrate and surface-treated electrodes corresponds to the usual design of displays of this type. The term "usual design" is hereby broadly generalized and also includes all derivatives and variants of LC displays, in particular including matrix display elements based on polysilicon TFTs or MIMs.

[0435] The following examples explain the present invention without limiting the present invention. However, they show preferred mixture concepts and preferably used compounds for those skilled in the art, as well as their respective concentrations and their combinations with each other. In addition, this example illustrates obtainable properties and property combinations.

[0436] Above and below, percentage data refer to percentages by weight; all temperatures are expressed in degrees Celsius.

[0437] Throughout this patent application, 1,4-cyclohexylene rings and 1,4-phenylene rings are depicted as follows:

[0438]

[0439] The cyclohexylene ring is a trans-1,4-cyclohexylene ring.

[0440] Throughout the present patent application and in the working examples, the structures of the liquid-crystalline compounds are indicated with the aid of acronyms. Unless otherwise indicated, the conversion into the chemical formulae is carried out according to Tables I to III. All groups CnH2n+1, CmH2m+1, CnH2n, CmH2m and CkH2k are respectively straight-chain alkyl or alkenyl groups, in each case with n, m or k C atoms; n and m each independently of one another represent 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, preferably 1, 2, 3, 4, 5 or 6, and k is 0, 1, 2, 3, 4, 5 or 6. The meaning of the symbols for the coding of the ring elements of the individual compounds in Table I, the listing of the bridging members in Table II and the indication of the left-hand and right-hand side chains of the compounds in Table III.

[0441] Table I: Ring elements

[0442]

[0443]

[0444]

[0445] Table II: Bridge Members

[0446]

[0447] Table III: Side Chains

[0448]

[0449]

[0450] Preferred mixture components are shown in Table A. In a preferred embodiment, the mixtures according to the invention comprise one or more compounds selected from Table A.

[0451] Table A

[0452] In the following formula, m and n are independently an integer from 1 to 12, preferably 1, 2, 3, 4, 5 or 6, k is 0, 1, 2, 3, 4, 5 or 6, and (O)C m H 2m+1 Meaning C m H 2m+1 or OC m H 2m+1 .

[0453]

[0454]

[0455]

[0456]

[0457]

[0458]

[0459]

[0460]

[0461]

[0462]

[0463]

[0464]

[0465]

[0466]

[0467]

[0468]

[0469]

[0470]

[0471]

[0472]

[0473]

[0474]

[0475]

[0476]

[0477]

[0478] Particularly preferred are liquid-crystalline mixtures which comprise at least one, two, three, four or more compounds from Table A.

[0479] Table B indicates possible dopants which are usually added to the mixtures according to the invention. The mixtures preferably comprise 0 to 10% by weight, in particular 0.001 to 5% by weight and particularly preferably 0.001 to 3% by weight of dopant.

[0480] Table B

[0481]

[0482]

[0483] Table C

[0484] Mention is made below of stabilizers which can be added to the mixture according to the invention, for example in an amount of 0 to 10% by weight.

[0485]

[0486]

[0487]

[0488]

[0489]

[0490]

[0491] Table D

[0492] Table D shows illustrative reactive mesogenic compounds which can be used in the LC media according to the invention. In a preferred embodiment, the mixture according to the invention comprises one or more reactive mesogens of the following table:

[0493]

[0494]

[0495]

[0496]

[0497]

[0498]

[0499]

[0500]

[0501]

[0502]

[0503]

[0504]

[0505]

[0506]

[0507]

[0508]

[0509]

[0510]

[0511]

[0512]

[0513]

[0514]

[0515]

[0516]

[0517]

[0518] In a preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds, preferably selected from the group consisting of polymerizable compounds of formulae RM-1 to RM-140. Among these, compounds RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM-40, RM-41, RM-42, RM-50, RM-53, RM-54, RM-56, RM-59, RM-66, RM-76, RM-78, RM-90, RM-93, RM-104, RM-105, RM-111, RM-119, RM-122, RM-123 and RM-124 are particularly preferred.

[0519] Table E

[0520] Table E shows self-aligning additives for vertical alignment which can be used in the LC media of SA-VA and SA-FFS displays according to the invention. In a preferred embodiment, the mixture according to the invention comprises at least one additive selected from the following compounds:

[0521]

[0522]

[0523]

[0524]

[0525]

[0526]

[0527]

[0528]

[0529]

[0530]

[0531]

[0532] In a preferred embodiment, the LC media and displays according to the invention comprise one or more SA additives selected from the group consisting of formulae SA-1 to SA-48, preferably formulae SA-14 to SA-48, very preferably formulae SA-20 to SA-34 and SA-48, preferably in combination with one or more RMs of formula M. DETAILED DESCRIPTION

[0533] The following examples are intended to illustrate the present invention rather than to limit it.

[0534] Above and below, unless expressly stated otherwise, all percentage data denote percentages by weight and relate to the entire corresponding mixture, including all solid or liquid-crystalline components, without solvent. Furthermore, unless expressly stated otherwise, all temperatures are expressed in degrees Celsius (° C.). mp = melting point, cl.p. = clearing point. Furthermore, C = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The data between these symbols denote transition temperatures.

[0535] In addition, the following abbreviations and symbols are used:

[0536] V0 Threshold voltage at 20°C, capacitive [V],

[0537] n e The extraordinary refractive index at 20°C and 589nm,

[0538] n o Ordinary refractive index at 20°C and 589nm,

[0539] △n Optical anisotropy at 20℃ and 589nm,

[0540] ε ⊥ The dielectric constant perpendicular to the director at 20°C and 1kHz,

[0541] ε || The dielectric constant parallel to the director at 20°C and 1kHz,

[0542] △ε Dielectric anisotropy at 20℃ and 1kHz,

[0543] cl.p., T ni Clearing point [℃],

[0544] γ1 Rotational viscosity at 20°C [mPa·s],

[0545] K1 elastic constant, "bending" deformation at 20°C [pN],

[0546] K2 elastic constant, "twist" deformation at 20°C [pN],

[0547] K3 Elastic constant, "bending" deformation at 20°C [pN].

[0548] Unless expressly stated otherwise in each case, all physical properties are and have been determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status, November 1997, Merck KGaA, Germany and apply to a temperature of 20°C.

[0549] Unless explicitly stated otherwise, the term "threshold voltage" used in the present invention relates to the capacitive threshold (V0), which is also called the Freedericks threshold. In an embodiment, as usual, the optical threshold may also be the relative contrast ratio (V 10 ) indicated.

[0550] Unless otherwise indicated, methods of preparing the test cells and measuring their electro-optical and other properties were performed by methods described below or analogous thereto.

[0551] The display used to measure the capacitive threshold voltage consisted of two plane-parallel glass outer plates separated by 25 μm, each with an electrode layer on the inside and an unrubbed polyimide alignment layer on top, which produced a homeotropic edge alignment of the liquid crystal molecules.

[0552] Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent.Therefore, the foregoing preferred specific embodiments should be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

[0553] In the foregoing and examples, unless otherwise indicated, all temperatures are set forth in degrees Celsius (uncorrected) and all parts and percentages are by weight.

[0554] The entire disclosure of all applications, patents and publications cited herein and the corresponding European application No. 20150435.4 filed on January 7, 2020 is incorporated herein by reference.

[0555] Comparative Example 1.1

[0556] The nematic LC host mixture C11 was prepared as follows.

[0557]

[0558]

[0559] Comparative Example 1.2

[0560] Nematic LC host mixture C12 was prepared as follows.

[0561]

[0562] Comparative Example 1.3

[0563] Nematic LC host mixture C13 was prepared as follows.

[0564]

[0565]

[0566] Comparative Example 1.4

[0567] Nematic LC host mixture C14 was prepared as follows.

[0568]

[0569] Example 1.1

[0570] Nematic LC host mixture N11 was prepared as follows.

[0571]

[0572] The mixture contains the compound of formula G CCG-VF.

[0573] Example 1.2

[0574] Nematic LC host mixture N12 was prepared as follows.

[0575]

[0576] The mixture contains compound CCG-3-F of formula G.

[0577] Example 1.3

[0578] Nematic LC host mixture N13 was prepared as follows.

[0579]

[0580] The mixture contains compound CCQG-3-F of formula G.

[0581] Comparative Example 2.1

[0582] Nematic LC host mixture C21 was prepared as follows.

[0583]

[0584] Example 2.1

[0585] Nematic LC host mixture N21 was prepared as follows.

[0586]

[0587] The mixture contains the compound of formula G CCG-VF.

[0588] The mixtures N11 to N13 and N21 according to the invention contain a positive compound of formula G with a terminal 3,4-difluorophenyl group. In contrast, the reference mixtures C11 to C14 and C21 do not contain a compound of formula G. Instead, these reference mixtures do not contain any positive compounds at all (C11, C21), or contain positive compounds CCP-3F.FF or DLGU-3-F with a terminal 3,4,5-trifluorophenyl group (C12, C14) or a positive compound CCP-3OCF3 with a terminal 4-trifluoromethoxyphenyl group (C13).

[0589] White flashing

[0590] The white flicker values ​​of the above mixtures were measured at 25° C. and 10 Hz in a UB-FFS test box. The flicker levels were determined for the voltages at gray levels 64, 127 and in the fully switched state V100 (corresponding to gray level 255).

[0591] Table 1 shows the results for mixtures C11 to C14 and N11 to N13, which were formulated to achieve the physical parameter target values ​​cl.p.

[0592] Table 1

[0593]

[0594] As can be seen from Table 1, the mixtures N11 to N13 according to the invention comprising the compound of formula G show significantly reduced scintillation at V100 compared to the reference mixtures C11 to C14 which do not comprise the compound of formula G.

[0595] Table 2 shows the results for mixtures C21 and N21, which were formulated to achieve the physical parameter target values ​​cl.p.

[0596] Table 2

[0597]

[0598] As can be seen from Table 2, the mixture N21 according to the invention comprising the compound of formula G shows significantly reduced flicker compared to the reference mixture C21 not comprising the compound of formula G at all grey levels.

[0599] The results show that the use of compounds of formula B and / or C in combination with compounds of formula G in dielectrically negative LC mixtures allows to reduce the flickering level while maintaining low viscosity and thus shortening the response time.

[0600] Example 3

[0601]

[0602] Example 4

[0603]

[0604] Example 5

[0605]

[0606] Example 6

[0607]

[0608] Example 7

[0609]

[0610] Example 8

[0611]

[0612]

[0613] Example 9

[0614]

[0615]

[0616] Example 10

[0617]

[0618] Embodiment 11

[0619]

[0620]

[0621] Example 12

[0622]

[0623] Embodiment 13

[0624]

[0625] Embodiment 14

[0626]

[0627]

[0628] Embodiment 15

[0629]

[0630] Example 16

[0631]

[0632]

[0633] Embodiment 17

[0634]

[0635] Embodiment 18

[0636]

[0637]

[0638] Embodiment 19

[0639]

[0640] Embodiment 20

[0641]

[0642]

[0643] Embodiment 21

[0644]

[0645] Embodiment 22

[0646]

[0647] Embodiment 23

[0648]

[0649]

[0650] Embodiment 24

[0651]

[0652] Embodiment 25

[0653]

[0654]

[0655] Embodiment 26

[0656]

[0657] Embodiment 27

[0658]

[0659] Embodiment 28

[0660]

[0661] Embodiment 29

[0662]

[0663] Embodiment 30

[0664]

[0665] Embodiment 31

[0666]

[0667]

[0668] Embodiment 32

[0669]

[0670] Embodiment 33

[0671]

[0672]

[0673] Embodiment 34

[0674]

[0675] Embodiment 35

[0676]

[0677]

[0678] Embodiment 36

[0679]

[0680] Embodiment 37

[0681]

[0682]

[0683] Embodiment 38

[0684]

[0685] Embodiment 39

[0686]

[0687]

[0688] Embodiment 40

[0689]

[0690] Embodiment 41

[0691]

[0692]

[0693] Embodiment 42

[0694]

[0695] Embodiment 43

[0696]

[0697]

[0698] Embodiment 44

[0699]

[0700] Embodiment 45

[0701] The mixture according to Example 44 was stabilized with 0.04% of the compound of the formula

[0702]

[0703] Embodiment 46

[0704]

[0705] Embodiment 47

[0706] The mixture according to Example 48 was stabilized with 0.04% of the compound of the formula

[0707] Embodiment 48

[0708]

[0709]

[0710] Embodiment 49

[0711] The mixture according to Example 48 was stabilized with 0.04% of the compound of the formula

[0712] Embodiment 50

[0713]

[0714]

[0715] Embodiment 51

[0716]

[0717] Embodiment 52

[0718]

[0719]

[0720] Embodiment 53

[0721]

[0722] Embodiment 54

[0723]

[0724]

[0725] Embodiment 55

[0726]

[0727] Embodiment 56

[0728]

[0729]

[0730] Embodiment 57

[0731]

[0732] Embodiment 58

[0733]

[0734]

[0735] Embodiment 59

[0736]

[0737] Embodiment 60

[0738]

[0739]

[0740] Embodiment 61

[0741]

[0742] Embodiment 62

[0743] The mixture according to Example 61 was stabilized with 0.04% of the compound of the formula

[0744] Embodiment 63

[0745] The mixture according to Example 61 was stabilized with 0.04% of the compound of the formula

[0746] Embodiment 64

[0747]

[0748] Embodiment 65

[0749] The mixture according to Example 64 was stabilized with 0.04% of the compound of the formula

[0750] Embodiment 66

[0751] The mixture according to Example 64 was stabilized with 0.04% of the compound of the formula

[0752] Embodiment 67

[0753]

[0754]

[0755] Embodiment 68

[0756] The mixture according to Example 67 was stabilized with 0.04% of the compound of the formula

[0757] Embodiment 69

[0758] The mixture according to Example 67 was stabilized with 0.04% of the compound of the formula

[0759] Embodiment 70

[0760] The mixture according to Example 67 was stabilized with 0.04% of the compound of the formula

[0761] Embodiment 71

[0762]

[0763]

[0764] Embodiment 72

[0765] The mixture according to Example 71 was stabilized with 0.04% of the compound of the formula

[0766] Embodiment 73

[0767] The mixture according to Example 71 was stabilized with 0.04% of the compound of the formula

[0768] Embodiment 74

[0769] The mixture according to Example 71 was stabilized with 0.04% of the compound of the formula

[0770] Embodiment 75

[0771]

[0772]

[0773] Embodiment 76

[0774] The mixture according to Example 75 was stabilized with 0.04% of the compound of the formula

[0775] Embodiment 77

[0776] The mixture according to Example 75 was stabilized with 0.04% of the compound of the formula

[0777] Embodiment 78

[0778] The mixture according to Example 75 was stabilized with 0.04% of the compound of the formula

[0779] Embodiment 79

[0780]

[0781] Embodiment 80

[0782] The mixture according to Example 79 was stabilized with 0.04% of the compound of the formula

[0783] Embodiment 81

[0784] The mixture according to Example 79 was stabilized with 0.04% of the compound of the formula

[0785] Embodiment 82

[0786] The mixture according to Example 79 was stabilized with 0.04% of the compound of the formula

[0787] Embodiment 83

[0788]

[0789] Embodiment 84

[0790] The mixture according to Example 83 was stabilized with 0.04% of the compound of the formula

[0791] Embodiment 85

[0792] The mixture according to Example 83 was stabilized with 0.04% of the compound of the formula

[0793]

[0794] Mixture Examples 3 to 85 show reduced or even no flicker while maintaining a relatively high clearing point, a high contrast ratio and a low rotational viscosity.

[0795] The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and / or operating conditions of this invention for those used in the preceding examples.

[0796] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope of the invention, can make various changes and modifications of the invention to adapt it to various usages and conditions.

Claims

1. A liquid crystal (LC) medium having a negative dielectric anisotropy and comprising one or more compounds selected from the group consisting of formulae B and C and one or more compounds of formula G The individual radicals, which are identical or different on each occurrence and independently of one another, have the following meanings: express R 0 , R 1 , R 2 is a straight-chain or branched alkyl or alkoxy group having 1 to 15 carbon atoms, wherein one or more CH2 in these groups may be each independently -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, and wherein in addition one or more H atoms may be replaced by halogen, preferably by F, L 1 , L 2 is F or Cl, X 0 is F, Cl, CN, SF5, SCN, NCS, a haloalkyl, haloalkenyl, haloalkoxy or haloalkenyloxy radical having up to 6 C atoms, Y 1 O, S or CH2O, Z 0 It is -C2H4-, -CH2O-, -CF2O-, -CH=CH- or a single bond.

2. LC medium according to claim 1, characterized in that The compound of formula B is selected from the following sub-formulas Where R 1 and R 2 has one of the meanings given in claim 1.

3. LC medium according to claim 1 or 2, characterized in that The compound of formula C is selected from the following sub-formula Where R 1 and R 2 has one of the meanings given in claim 1.

4. LC medium according to one or more of claims 1 to 3, characterized in that The compound of formula G is selected from the following sub-formula Where R 0 has one of the meanings given for the formula G in claim 1 .

5. LC medium according to one or more of claims 1 to 4, characterized in that It further comprises one or more compounds selected from the group consisting of formula CY and PY Wherein, each group has the following meaning: a means 1 or 2, b represents 0 or 1, express R 1 and R 2 each independently of one another represents an alkyl group having 1 to 12 C atoms, wherein, in addition, one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -O-CO- or -CO-O- in such a way that the O atoms are not directly connected to one another, Z x Indicates -CH=CH-, -CH2O-, -OCH2-, -CF2O-, -OCF2-, -O-, - CH2-, -CH2CH2- or a single bond, L 1-4 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2, and L 5 It is H or CH3.

6. LC medium according to one or more of claims 1 to 5, characterized in that It further comprises one or more compounds selected from the group consisting of formulae ZK and DK: Wherein, each radical has the following meanings identically or differently at each occurrence: Display express express and R 3 and R 4 Each independently has the 1 The meaning given, Z y represents -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF- or a single bond, R 5 and R 6 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms, e represents 1 or 2.

7. LC medium according to one or more of claims 1 to 6, characterized in that It further comprises one or more compounds selected from the following formulae: Therein, alkyl and alkyl* each independently of one another represent a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl and alkenyl* each independently of one another represent a straight-chain alkenyl radical having 2 to 6 C atoms.

8. LC medium according to one or more of claims 1 to 7, characterized in that It also contains one or more compounds of the formula where the individual radicals are identical or different on each occurrence and independently have the following meanings R 1 , R 2 Each independently has the 1 The meaning given, L T1 -L T6 is H, F or Cl, where L T1 To L T6 At least one of is F or Cl.

9. LC display comprising an LC medium as defined in one or more of claims 1 to 8.

10. The LC display according to claim 9, which is a VA, SA-VA, IPS, PS-IPS, FFS, PS-FFS, UB-FFS or PS-UB-FFS display.

11. Process for the preparation of an LC medium according to one or more of claims 1 to 8, comprising the step of mixing one or more compounds of the formula B and / or C or subformulae thereof as defined in any of claims 1 to 3 with one or more compounds of the formula G as defined in claim 1 or 4, and optionally with further LC compounds and / or additives.

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