Liquid-crystalline medium

Abstract

The present invention relates to liquid-crystalline media comprising at least one compound of formula I: wherein R 1 have the meaning of claim 1 ; and also to the use thereof in liquid-crystalline media and optoelectronic liquid-crystalline displays.

Description

[0001] This application is a divisional application of the application with the application date of August 15, 2014, the application number of 201410401181.9, and the invention title of "Liquid-crystalline medium". TECHNICAL FIELD

[0002] The present application relates to a liquid-crystalline medium (LC medium), to the use thereof for electro-optical purposes, and to a liquid-crystalline display comprising the medium. BACKGROUND

[0003] Liquid crystals are used primarily as dielectrics in display devices, since the optical properties of such substances can be changed by an applied voltage. Electro-optical devices based on liquid crystals are extremely well known to the person skilled in the art and can be based on various effects. Examples of such devices are cells with dynamic scattering, DAP (deformation of aligned phase) cells, guest / host cells, TN cells with twisted nematic structure, STN (super twisted nematic) cells, SBE (super birefringence effect) cells and OMI (optical mode interference) cells. The most common display devices are based on the Schadt-Helfrich effect and have a twisted nematic structure. Furthermore, there are cells which work with an electric field parallel to the substrate and the liquid-crystalline layer, for example IPS (in-plane switching) cells. In particular, TN, STN, FFS (fringe field switching) and IPS cells are currently commercially interesting fields of application for the media according to the application.

[0004] The liquid-crystalline material must have good chemical and thermal stability and good stability to electric fields and electromagnetic radiation. Furthermore, the liquid-crystalline material should have a low viscosity and lead to short addressing times, low threshold voltages and high contrast ratios in the cell.

[0005] Furthermore, they should have suitable mesophases in the widest possible range of the usual operating temperatures, i.e. above and below room temperature, for example nematic mesophases or cholesteric mesophases for the above-mentioned cells. Since liquid crystals are usually used as mixtures of a plurality of components, it is important that the components are readily miscible with one another. Further properties such as electrical conductivity, dielectric anisotropy and optical anisotropy must meet various requirements depending on the cell type and the field of application. For example, materials for cells with twisted nematic structure should have a positive dielectric anisotropy and a low electrical conductivity.

[0006] For example, for matrix liquid-crystal displays (MLC displays) with integrated non-linear elements to switch individual pixels, media with a large positive dielectric anisotropy, a wide nematic phase, a relatively low birefringence, a very high resistivity, good UV and temperature stability and a low vapour pressure are desirable.

[0007] Matrix liquid crystal displays of this type are known. An example of a non-linear element that can be used to independently switch individual pixels is an active element (i.e. a transistor). The term "active matrix" is then used, which can be distinguished in two types:

[0008] 1. MOS (Metal Oxide Semiconductor) or other diodes on silicon wafers as substrate.

[0009] 2. Thin Film Transistors (TFT) on glass plates as substrate.

[0010] The use of single crystal silicon as a substrate material limits the display size, because even the assembly of modules of different displays causes problems at the joints.

[0011] In the case of the preferred more promising type 2, the electro-optical effect used is usually the TN effect. A distinction is made between TFTs containing compound semiconductors such as CdSe, or TFTs based on polycrystalline or amorphous silicon. For the latter technique, intensive work is being carried out worldwide.

[0012] The TFT matrix is applied to the inside of one glass plate of the display, while the other glass plate has a transparent counter electrode on its inside. The TFTs are very small compared to the size of the pixel electrodes and have hardly any adverse effect on the image. The technique can also be extended to full colour functional displays, in which a mosaic of red, green and blue filters is arranged in such a way that the filter elements are opposite each switchable pixel.

[0013] TFT displays usually operate as TN cells with crossed polarisers in transmission and are backlit.

[0014] The term MLC display includes here any matrix display with integrated non-linear elements, i.e. in addition to active matrices, also displays with passive elements, such as variable resistors or diodes (MIM = Metal-Insulator-Metal).

[0015] Such MLC displays are particularly suitable for TV applications (e.g. pocket TV) or for high information displays in computer applications (laptop) and in car or aircraft construction. In addition to the problems with the angle dependence of contrast and response time, some difficulties also arise in MLC displays due to the insufficiently high resistivity of the liquid crystal mixtures [TOGASHI, S., SEKI-GUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K., TAJIMA, E., WATANABE, H., SHIMIZU, H., Proc. Eurodisplay 84, September 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, pp. 141 ff., Paris; STROMER, M., Proc. Eurodisplay 84, September 1984: Design of Thin Film Transistors for Matrix Addressing of Television Liquid Crystal Displays, pp. 145 ff., Paris]. With decreasing resistance, the contrast of the MLC display deteriorates and problems with the elimination of residual images can occur. Since the resistivity of the liquid crystal mixture generally decreases with the lifetime of the MLC display due to interactions with the internal surfaces of the display, a high (initial) resistance is very important in order to achieve an acceptable service life. It has not been possible to achieve very high resistivity values to date, particularly with low-voltage mixtures. It is also important that the resistivity shows a minimum possible increase with increasing temperature and after heating and / or UV exposure. The low-temperature behaviour of the mixtures from the prior art is also particularly disadvantageous. Crystallisation and / or smectic phase should not occur even at low temperatures, and the temperature dependence of the viscosity should be as low as possible. MLC displays from the prior art therefore do not meet today's requirements.

[0016] Besides liquid-crystalline displays which work with backlighting, i.e. transmissive and, if desired, transflectively, reflective liquid-crystalline displays are of particular interest. These reflective liquid-crystalline displays use ambient light for the information display. They therefore consume significantly less energy than backlit liquid-crystalline displays of corresponding size and resolution. Since the TN effect is characterized by very good contrast, such reflective displays can even be read well in bright ambient conditions. This has already been known with simple reflective TN displays, such as those used, for example, in watches and pocket calculators. However, the principle can also be used for high-quality, higher-resolution, actively matrix-addressed displays, for example TFT displays. Here, as already in the generally customary transmissive TFT-TN displays, the use of liquid crystals of low birefringence (Δn) is necessary in order to achieve a low optical retardation (d-Δn). This low optical retardation leads to a low viewing-angle dependence of the generally acceptable contrast (cf. DE 30 22 818). In reflective displays, the application of low-birefringence liquid crystals is even more important than in transmissive displays, since the effective layer thickness through which the light passes in a reflective display is approximately twice as great as in a transmissive display with the same layer thickness.

[0017] For TV and video applications, displays with fast response times are required in order to be able to reproduce multimedia contents, such as films and video games, in near-realistic quality. In particular, such short response times can be achieved if liquid-crystalline media with low values of the rotational viscosity γ1 and with high optical anisotropy (Δn) are used.

[0018] For the 3D effect by shutter glasses, in particular fast-switching mixtures with low rotational viscosity and correspondingly high optical anisotropy (Δn) are used. The use of mixtures with high optical anisotropy (Δn) makes it possible to use electro-optical lens systems by means of which a 2-dimensional presentation of a display can be converted into a 3-dimensional autostereoscopic presentation.

[0019] There is therefore a great demand for MLC displays which have a very high specific resistance at the same time as a large operating temperature range, short response times (even at low temperatures) and low threshold voltages, which do not exhibit or only to a small extent exhibit these disadvantages.

[0020] In the case of a TN (Schadt-Helfrich) cell, media are desired which contribute to the following advantages in the cell:

[0021] - broadened nematic phase range (down to low temperatures)

[0022] - ability to switch at very low temperatures (outdoor applications, automotive, avionics)

[0023] - improved resistance to UV radiation (longer storage life)

[0024] - low threshold voltage.

[0025] The media available from the prior art cannot achieve these advantages while at the same time maintaining the other parameters.

[0026] In the case of super twisted (STN) cells, media which contribute to greater multiplexability and / or lower threshold voltage and / or a wider nematic phase range, in particular at low temperatures, are desirable. For this reason, there is an urgent need to further expand the range of parameters (clearing point, smectic-nematic phase transition point or melting point, viscosity, dielectric parameters, elastic parameters) which can be utilized.

[0027] One of the most important properties of modern LCDs is the correct representation of moving images. If the response speed of the liquid-crystalline medium used is too slow, this leads to undesirable artefacts in the display in this case. The physical parameters which essentially determine the response time of a liquid-crystalline mixture are the rotational viscosity γ1and the elastic constants. The latter are also of particular importance for ensuring a good black state of the LCD. However, it is generally observed that the clearing point of the mixture and thus the rotational viscosity of the mixture also increase with increasing elastic constants, which means that an improvement in the response time is not possible. In particular in the case of liquid-crystalline displays for TV and video applications (e.g. LCD TVs, monitors, PDAs, notebooks, game consoles), it is desirable for the response time to be significantly shortened. Reducing the layer thickness d ("cell gap") of the liquid-crystalline medium in the liquid-crystalline cell theoretically leads to faster response times, but requires the liquid-crystalline medium to have a higher birefringence Δn in order to ensure sufficient optical retardation (d Δn). However, the liquid-crystalline materials of high birefringence known from the prior art generally also have a high rotational viscosity, which in turn has a disadvantageous effect on the response time.

[0028] There is therefore a need for liquid-crystalline media which simultaneously have a fast response time, a low rotational viscosity and a high birefringence. SUMMARY

[0029] It is an object of the present application to provide media, in particular for MLC, TN, STN, OCB, positive VA, FFS, PS (= polymer stabilized)-FFS, IPS, PS-IPS displays of this type, which have the desired properties explained above and do not exhibit or only exhibit the disadvantages explained above to a reduced extent. In particular, the LC media should have a fast response time and a low rotational viscosity at a relatively high birefringence at the same time. Furthermore, the LC media should have a high clearing point, a high dielectric anisotropy, a low threshold voltage and a very good low-temperature stability (LTS).

[0030] It has now been found that this object is achieved if an LC medium comprising one or more compounds of formula I is used.

[0031] The present application relates to a liquid-crystalline medium, characterized in that it comprises one or more compounds of formula I

[0032]

[0033] wherein

[0034] R 1 represents an alkyl or alkoxy group having 1 to 15 C atoms, where, in addition, one or more CH2 groups in these radicals can each be replaced, independently of one another, by -C≡C-, -CF2O-, -CH=CH-, -O-, -CO-O-, -O-CO-, where, in addition, one or more H atoms can be replaced by halogen.

[0035] The compounds of formula I lead to LC mixtures having the above-mentioned desired properties, in particular to LC mixtures having a very low rotational viscosity. The mixtures according to the application have a very large elastic constant and thus contribute to very good response times. In addition, the mixtures according to the application are stable at least at -20°C and do not exhibit a tendency to crystallize. The rotational viscosity γ1 is usually < 120 mPa-s. In addition, the mixtures according to the application are characterized by a very good ratio of rotational viscosity γ1 and clearing point, a high value of the optical anisotropy Δε and a high birefringence Δn, as well as fast response times, low threshold voltage, high clearing point, high positive dielectric anisotropy and broad nematic phase range. In addition, the compounds of formula I are also very easy to dissolve in liquid-crystalline media.

[0036] The compounds of formula I have a wide range of applications and are in particular characterized by their very large elastic constant. Depending on the choice of substituents, they can be used as basic material for the predominant composition in liquid-crystalline media; however, liquid-crystalline basic materials from other classes of compounds can also be added to the compounds of formula I in order to influence, for example, the dielectric and / or optical anisotropy of this type of dielectric and / or to optimize its threshold voltage and / or its rotational viscosity. As a result, the LC mixtures according to the application support a good display black state, which is crucial for the contrast of the display, due to the high elastic constant and at the same time this also contributes to very good response times.

[0037] R in the compounds of formula I and subformulae 1Preferably, it denotes a straight-chain alkyl group, in particular having 3 to 5 C atoms. In other preferred embodiments, one or more CH2groups in the alkyl group can also be replaced by -CH=CH-.

[0038] Particularly preferred compounds of the formula I are shown below:

[0039]

[0040]

[0041] Very particularly preferred are compounds of the formula I-2.

[0042] In pure form, the compounds of the formula I are colourless and form liquid-crystalline mesophases in the temperature range which is advantageous for electrooptical use. They are chemically, thermally and also photostable.

[0043] The compounds of the formula I are prepared by methods known per se, such as those described in the literature (for example in the standard works such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), under reaction conditions which are known and suitable for the said reactions. Here, it is also possible to carry out the methods in a manner known per se, but not very close to the application. The compounds of the formula I can be prepared, for example, according to the following methods:

[0044] Scheme 1

[0045]

[0046] Scheme 2

[0047]

[0048] If R in the context of the formulae 1 denotes alkyl and / or alkoxy, it can be straight-chain or branched. It is preferably straight-chain, has 2, 3, 4, 5, 6 or 7 C atoms and thus preferably denotes ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy, furthermore nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy or tetradecyloxy.

[0049] Oxaalkyl preferably denotes a straight-chain 2-oxapropyl (= methoxy-methyl), 2- (= ethoxymethyl) or 3-oxabutyl (= 2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4-, or 5-oxahexyl, 2-, 3-, 4-, 5-, or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl.

[0050] R 1 denotes alkyl in which one CH2group has been replaced by -CH=CH-, which can be straight-chain or branched. It is preferably straight-chain and has 2 to 10 C atoms. Accordingly, it particularly denotes vinyl, 1- or 2-propenyl, 1-, 2- or 3-butenyl, 1-, 2-, 3- or 4-pentenyl, 1-, 2-, 3-, 4- or 5-hexenyl, 1-, 2-, 3-, 4-, 5- or 6-heptenyl, 1-, 2-, 3-, 4-, 5-, 6- or 7-octenyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- or 8-non enyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-decenyl. These radicals can also be mono- or polyhalogenated. Preferred fluorinated radicals are CH=CF2, CF=CF2, CF=CHF, CH=CHF.

[0051] R 1 denotes alkyl or alkenyl which is at least monosubstituted by halogen, this radical is preferably straight-chain and the halogen is preferably F or CI. In the case of multiple substitution, the halogen is preferably F. The resulting radicals also include perfluorinated radicals. In the case of monosubstitution, the fluorine or chlorine substituent can be in any desired position, but it is preferably in the omega position.

[0052] Further preferred embodiments are shown below:

[0053] - the medium also comprises one or more neutral compounds of the formulae II and / or III,

[0054]

[0055] wherein

[0056] A denotes 1,4-phenylene or trans-1,4-cyclohexylene,

[0057] a is 0 or 1,

[0058] R 3 denotes alkenyl having 2 to 9 C atoms,

[0059] and R 4 has the meaning of R 1The meaning shown is, and it preferably represents, an alkyl group having 1 to 12 carbon atoms or an alkenyl group having 2 to 9 carbon atoms.

[0060] - The compounds of formula II are preferably selected from compounds of the following formula:

[0061]

[0062] Where R 3a and R 4a Each of these can be independently represented by H, CH3, C2H5, or C3H7, and "alkyl" indicates a straight-chain alkyl group having 1 to 8 carbon atoms. Compounds of formulas IIa and IIf are particularly preferred, especially those in which R... 3a Compounds representing H or CH3, and compounds of formula IIc, especially those containing R 3a and R 4a It represents H, CH3, or C2H5.

[0063] Furthermore, compounds of formula II with non-terminal double bonds on the alkenyl side chain are preferred:

[0064]

[0065] The most particularly preferred compounds of Formula II are those of the following formula:

[0066]

[0067]

[0068]

[0069] Among the compounds of formulas IIa-1 to IIa-19, compounds of formulas IIa-1, IIa-2, IIa-3 and IIa-5 are particularly preferred.

[0070] In addition to one or more compounds of formula I, the liquid crystal medium according to the present invention particularly preferably contains compounds of formula (CC-3-V):

[0071]

[0072] Based on the mixture, its concentration is preferably 5-70% by weight, particularly 10-50% by weight, and very particularly preferably 20-45% by weight.

[0073] The preferred compound of formula IIb is the compound of the following formula:

[0074]

[0075]

[0076] Preferred compounds of the formula lie are compounds of the following formula:

[0077]

[0078] The compounds of the formula III are preferably selected from the following formulae:

[0079]

[0080] in which "alkyl" and R 3a have the meanings indicated above and R 3a Preferably, R represents H or CH3. Particularly preferred are compounds of the formula IlIb;

[0081] Very particularly preferred are compounds of the formula IIIb-1 :

[0082]

[0083] in which "alkyl" has the meanings indicated above and preferably represents CH3, also C2H5 or n-C3H7.

[0084] The medium preferably also comprises one or more compounds selected from the following formulae IV to VIII:

[0085]

[0086] in which

[0087] R 0 have the meanings indicated in claim 6,

[0088] X 0 represents F, Cl, mono- or polyfluorinated alkyl or alkoxy, in each case having 1 to 6 C atoms, mono- or polyfluorinated alkenyl or alkenyloxy, in each case having 2 to 6 C atoms.

[0089] Y 1-6 each, independently of one another, represents H or F,

[0090] Z 0 represents -C2H4-, -(CH2)4-, -CH=CH-, -CF=CF-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH2O-, -OCH2-, -COO-, -CF2O- or -OCF2-, in formulae V and VI also a single bond, and

[0091] -CF2CH2-, -CH2O-, -OCH2-, -COO-, -CF2O- or -OCF2-, in formulae V and VI also a single bond, and

[0092] r represents 0 or 1.

[0093] In the above formulae, X 0F, CI or a mono- or polyfluorinated alkyl or alkoxy group having 1, 2 or 3 C atoms or a mono- or polyfluorinated alkenyl or alkenyloxy group having 2 or 3 C atoms. X 0 F, CI, CF3, CHF2, OCF3, OCHF2, OCHFCF3, OCHFCHF2, OCHFCH2F, OCF2CH3, OCF2CHF2, OCF2CH2F, OCF2CF2CHF2, OCF2CF2CH2F, OCFHCF2CF3, OCFHCF2CHF2, OCH=CF2, OCF=CF2, OCF2CHFCF3, OCF2CF2CF3, OCF2CF2CCIF2, OCCIFCF2CF3, CF=CF2, CF=CHF, OCH=CF2, OCF=CF2 or CH=CF2.

[0094] In the compounds of the formulae IV to VIII, X 0 preferably denotes F or OCF3, furthermore OCHF2, CF3, CF2H, CI, OCH=CF2. R 0 preferably denotes a linear alkyl or alkenyl group having up to 6 C atoms.

[0095] The compounds of the formula IV are preferably selected from the following formulae:

[0096]

[0097]

[0098] wherein R 0 and X 0 have the meanings indicated in claim 6.

[0099] In the compounds of the formula IV, R 0 preferably denotes an alkyl group having 1 to 8 C atoms and X 0 preferably denotes F, CI, OCHF2 or OCF3, furthermore OCH=CF2. In the compounds of the formula IVb, R 0 preferably denotes an alkyl or alkenyl group. In the compounds of the formula IVd, X 0 preferably denotes CI, furthermore F.

[0100] The compounds of the formula V are preferably selected from the following formulae Va to Vj:

[0101]

[0102]

[0103] wherein R 0 and X 0 have the meanings indicated in claim 6. In the compounds of the formula V, R0 Indicates an alkyl group having 1 to 8 carbon atoms and X 0 This indicates F, OCF3, or OCH=CF2.

[0104] -The medium contains one or more compounds of formula VI-1:

[0105]

[0106] Those selected from the following formulas are particularly preferred:

[0107]

[0108] Where R 0 and X 0 It has the meaning described in claim 6. Preferably, R in formula VI 0 Indicates an alkyl group having 1 to 8 carbon atoms and X 0 It represents F, and there are also CF3 and OCF3.

[0109] -The medium contains one or more compounds of formula VI-2:

[0110]

[0111] Those selected from the following formulas are particularly preferred:

[0112]

[0113]

[0114] Where R 0 and X 0 It has the meaning described in claim 6. Preferably, R in formula VI 0 Indicates an alkyl group having 1 to 8 carbon atoms and X 0 Indicate F;

[0115] -The medium preferably comprises one or more compounds of formula VII, wherein Z 0 The expression is -CF2O-, -CH2CH2-, or -COO-, with particular preference given to those selected from the following formulas:

[0116]

[0117] Where R 0 and X 0 It has the meaning described in claim 6. Preferably, R in formula VII 0 Indicates an alkyl group having 1 to 8 carbon atoms and X 0 It represents F, as well as OCF3 and CF3.

[0118] Compounds of formula VIII are preferably selected from those of the following formulas:

[0119]

[0120]

[0121] wherein R 0 and X 0 have the meanings indicated above. R 0 preferably denotes a straight-chain alkyl group having 1 to 8 C atoms. X 0 preferably denotes F.

[0122] - the medium further comprises one or more compounds of the following formula:

[0123]

[0124] wherein R 0 , X 0 , Y 1 and Y 2 have the meanings indicated above, and each, independently of the others, denotes wherein ring A and B do not simultaneously denote 1,4-cyclohexylene;

[0125] - the compounds of the formula IX are preferably selected from those of the following formulae:

[0126]

[0127]

[0128] wherein R 0 and X 0 have the meanings indicated in claim 6. Preferably, R 0 in the formula IX denotes an alkyl group having 1 to 8 C atoms and X 0 denotes F. Particularly preferred are compounds of the formula IXa.

[0129] - the medium further comprises one or more compounds selected from the following formulae:

[0130]

[0131] wherein R 0 , X 0 and Y 1-4 have the meanings indicated in claim 6, and each, independently of the others, denotes

[0132] - the compounds of the formulae X and XI are preferably selected from those of the following formulae:

[0133]

[0134]

[0135] wherein R 0 and X 0 have the meaning described in claim 6. Preferably, R 0 denotes alkyl having 1 to 8 C atoms and X 0 denotes F. Particularly preferred compounds are those wherein Y 1 denotes F and Y 2 denotes H or F, preferably F.

[0136] - the medium further comprises one or more compounds of the following formula XII:

[0137]

[0138] wherein R 1 and R 2 each, independently of the other, denote alkyl, alkenyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyloxy, each having up to 9 C atoms, and preferably each, independently of the other, denote alkyl or alkenyl having 1 to 8 C atoms or 2 to 8 C atoms.

[0139] Preferred compounds of the formula XII are compounds of the following formula:

[0140]

[0141] wherein alkyl and alkyl* each, independently of the other, denote linear alkyl having 1 to 8 C atoms, and

[0142] alkenyl and alkenyl* each, independently of the other, denote linear alkenyl having 2 to 8 C atoms.

[0143] Particularly preferred are compounds of the formulae XII-2 and XII-4.

[0144] Particularly preferred compounds of the formula XII-2 are compounds of the formulae XII-2a, XII-2b and XII-2c.

[0145]

[0146] Particularly preferred compounds of the formula XII-4 are compounds of the formulae XII-4a, XII-4b and XII-4c.

[0147]

[0148] The compounds of the formula XII are preferably used in an amount of 3 to 40 % by weight.

[0149] The medium further comprises one or more compounds selected from the group consisting of the following formulae:

[0150]

[0151] wherein R 0 , X 0 , Y 1 and Y 2 have the meaning given in claim 6. Preferably, R 0 represents an alkyl group having 1 to 8 C atoms and X 0 represents F or CI;

[0152] The compounds of the formulae XIII and XIV are preferably selected from the group consisting of the following formulae:

[0153]

[0154] wherein R 0 and X 0 have the meaning given in claim 6. R 0 preferably represents an alkyl group having 1 to 8 C atoms. In the compounds of the formula XIII, X 0 preferably represents F or CI.

[0155] The medium further comprises one or more compounds of the formulae D1, D2, D3, D4 and / or D5:

[0156]

[0157] wherein Y 1 , Y 2 , R 0 and X 0 have the meaning given in claim 6. Preferably, R 0 represents an alkyl group having 1 to 8 C atoms and X 0 represents F.

[0158] Particularly preferred are the compounds of the following formula:

[0159]

[0160] wherein R 0 has the meaning given above and preferably it represents a linear alkyl group having 1 to 6 C atoms, in particular C2H5, n-C3H7 or n-C5H 11 .

[0161] The medium further comprises one or more compounds of the following formula XVII:

[0162]

[0163] wherein Y 1R 1 and R 2 have the meanings indicated above. R 1 and R 2 each, independently of one another, preferably denote alkyl or alkenyl having 1 or 2 to 8 C atoms; Y 1 and Y 2 each preferably denote F. The compounds of the formula XVII are preferably used in an amount of 3 to 30 % by weight, based on the medium.

[0164] The medium furthermore comprises one or more compounds of the formulae

[0165]

[0166] where X 0 , Y 1 and Y 2 have the meanings indicated in claim 6, and "alkenyl" denotes C 2-7 -alkenyl. Particularly preferred are compounds of the formula

[0167]

[0168] where R 3a has the meanings indicated above and preferably denotes H;

[0169] The medium furthermore comprises one or more tetra- cyclic compounds selected from XIX to XXVII:

[0170]

[0171]

[0172]

[0173] where Y 1-4 , R 0 and X 0 each, independently of one another, have one of the meanings indicated above. X 0 is preferably F, CI, CF3, OCF3 or OCHF2. R 0 preferably denotes alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl each having up to 8 C atoms.

[0174] In the compounds of the formulae XIX to XXVIII, R 0 preferably denotes linear alkyl. X 0 preferably denotes F or OCF3, furthermore CF3. Y 1 and Y 2 preferably denote Y 1 = F and Y 2 = H or Y 1= Y 2 = F.

[0175] Particularly preferred compounds of the formulae XIX to XXVIII are those in which X 0 Preferred compounds of the formula XXV are those in which Y represents F, furthermore OCF3.

[0176] Preferred mixtures comprise at least one compound selected from S-1, S-2, S-3 and S-4:

[0177]

[0178]

[0179] Since these compounds in particular contribute to the inhibition of the smectic phase of the mixture.

[0180] The medium preferably comprises one or more neutral compounds of the general formula N:

[0181]

[0182] in which

[0183] R N1 and R N2 each, independently of the other, denotes an alkyl or alkoxy radical having 1 to 15 C atoms, in which, furthermore, one or more CH2groups in these radicals can each be replaced, independently of the others, by -C≡C-, -CF2O-, -OCF2-, -CH2O-, -O-, -CO-O-, -O-CO-, and in which, furthermore, one or more H atoms can be replaced by halogen,

[0184] Ring A N1 , A N2 and A N3 each, independently of the others, denotes 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, trans-1,4-cyclohexylene, in which, furthermore, one or two CH2groups can be replaced by -O-, or 1,4-cyclohexenylene,

[0185] Z N1 and Z N2 each, independently of the others, denotes a single bond, -CH2CH2-, -COO-, -OCO-, -C≡C-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -CH=CH-,

[0186] n denotes 0, 1 or 2.

[0187] Preferred compounds of the formula N are shown below:

[0188]

[0189]

[0190]

[0191]

[0192]

[0193] wherein

[0194] alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1 to 9 C atoms, preferably having 2 to 6 C atoms, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms.

[0195] Among the compounds of the formula N, particular preference is given to the compounds of the formulae N-1, N-2, N-3, N-4, N-8, N-9, N-14, N-15, N-17, N-18, N-19, N-20, N-21, N-22, N-23, N-24, N-25, N-31, N-33 and N-36.

[0196] The medium furthermore comprises one or more compounds of the formulae St-1 to St-3:

[0197]

[0198]

[0199] wherein R 0 , Y 1 , Y 2 and X 0 have the meanings indicated in claim 6. R 0 preferably denotes a straight-chain alkyl radical, which preferably has 1 -6 C atoms. X 0 is preferably F, CF3 or OCF3. Y 1 preferably denotes F. Y 2 preferably denotes F. Furthermore, preference is given to compounds in which Y 1 = F and Y 2 = H. The compounds of the formulae St-1 to St-3 are preferably used in the mixtures according to the application at a concentration of 3-30% by weight, in particular 5-25% by weight.

[0200] The medium furthermore comprises one or more pyrimidine or pyridine compounds of the formulae Py-1 to Py-5:

[0201]

[0202]

[0203] wherein R 0 is preferably linear alkyl having 2 to 5 C atoms. x denotes 0 or 1, preferably x = 1. Preferred mixtures comprise 3 to 30 % by weight, in particular 5 to 20 % by weight, of this / these pyrimidine compound(s).

[0204] - the medium further comprises one or more compounds selected from the group consisting of formulae Y-1, Y-2, Y-3 and Y-4:

[0205]

[0206] wherein

[0207] R 2A denotes H, alkyl or alkoxy having 1 to 15 C atoms, in which, furthermore, one or more CH2groups in these radicals can each be replaced, independently of one another, by -C≡C-, -CF2O-, -CH=CH-, -O-, -CO-O-, -O-CO-, and furthermore in which one or more H atoms can be replaced by halogen,

[0208] L 1-4 and L 2 each, independently of one another, denote F, Cl, CF3or CHF2, preferably each denote F,

[0209] Z 2 and Z 2’ each, independently of one another, denote a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CH=CHCH2O-,

[0210] p denotes 0, 1 or 2,

[0211] q denotes 0 or 1,

[0212] (O)C v H 2v+1 denotes OC v H 2v+1 or C v H 2v+1 and

[0213] v denotes 1 to 6.

[0214] Particularly preferred compounds of formulae Y-1 to Y-4 are shown below:

[0215]

[0216]

[0217]

[0218]

[0219]

[0220] Among the compounds shown, particular preference is given to compounds of the formulae Y-1 a, Y-1 c, Y-1 e, Y-1 g, Y-1 j, Y-1 r, Y-1 t, Y-2b, Y-2h, Y-2j and Y-3a.

[0221] The proportion of compounds of the formulae Y-1 to Y-3 in the mixtures according to the application is preferably 0 to 30% by weight.

[0222] In the formulae given above and below, fe optimally represents

[0223]

[0224]

[0225] -R 0 preferably a straight-chain alkyl or alkenyl group having 2 to 7 C atoms;

[0226] -X 0 preferably F, furthermore OCF3, OCH=CF2, CI or CF3;

[0227] - the medium preferably comprises one, two or three compounds of the formula I;

[0228] - the medium preferably comprises one or more compounds selected from the group of compounds of the formulae I, II, III, V, VI-1, VI-2, XII, XIII, XIV, XVII, XXIII, XXV;

[0229] - the medium preferably comprises one or more compounds of the formula VI-1 ;

[0230] - the medium preferably comprises one or more compounds of the formula VI-2;

[0231] - the medium preferably comprises 1 to 30% by weight, preferably 2 to 20% by weight, particularly preferably 2 to 15% by weight, of compounds of the formula I;

[0232] - the proportion of compounds of the formulae II to XXVII in the overall mixture is preferably 20 to 99% by weight;

[0233] - the medium preferably comprises 25 to 80 % by weight, particularly preferably 30 to 70 % by weight, of compounds of the formulae II and / or III;

[0234] - the medium preferably comprises 0 to 70 % by weight, particularly preferably 20 to 60 % by weight, of compounds of the formula Ila-1 ;

[0235] - the medium preferably comprises 0 to 25 % by weight, particularly preferably 5 to 25 % by weight, of compounds of the formula Ila-2;

[0236] - the medium preferably comprises 0 to 30 % by weight, particularly preferably 5 to 25 % by weight, of compounds of the formula Ila-3;

[0237] - the medium preferably comprises 0 to 25 % by weight, particularly preferably 5 to 25 % by weight, of compounds of the formula Ila-5;

[0238] - the medium preferably comprises 5 to 40 % by weight, particularly preferably 10 to 30 % by weight, of compounds of the formula V;

[0239] - the medium preferably comprises 3 to 30 % by weight, particularly preferably 6 to 25 % by weight, of compounds of the formula VI-1 ;

[0240] - the medium preferably comprises 2 to 30 % by weight, particularly preferably 4 to 25 % by weight, of compounds of the formula VI-2;

[0241] - the medium preferably comprises 5 to 40 % by weight, particularly preferably 10 to 30 % by weight, of compounds of the formula XII;

[0242] - the medium preferably comprises 1 to 25 % by weight, particularly preferably 2 to 15 % by weight, of compounds of the formula XIII;

[0243] - the medium preferably comprises 5 to 45 % by weight, particularly preferably 10 to 35 % by weight, of compounds of the formula XIV;

[0244] - the medium preferably comprises 1 to 20 % by weight, particularly preferably 2 to 15 % by weight, of compounds of the formula XVI;

[0245] - the medium preferably comprises 5 to 30 % by weight, particularly preferably 8 to 22 % by weight, of compounds of the formula Va, in which X 0 = OCH=CF2;

[0246] - the medium preferably comprises compounds of the formula CC-3-2V and compounds of the formulae CC-3-V and / or CC-3-V1 ;

[0247] - the medium preferably comprises compounds of the formula CC-3-2V and compounds of the formulae APUQU-2-F and / or APUQU-3-F;

[0248] - the medium preferably comprises a compound of formula CC-3-2V and a compound of formula CC-3-2V1 ;

[0249] - the medium preferably comprises a compound of formula CC-3-2V and a compound of formula PP-1-2V1 ;

[0250] - the medium preferably comprises a compound of formula CC-3-2V and at least one compound of formula PGUQU-n-F, wherein n = 3, 4 or 5;

[0251] - the medium preferably comprises a compound of formula CC-3-2V and at least one compound of formula DPGU-n-F, wherein n = 2, 3, 4 or 5;

[0252] It has been found that even a relatively small proportion of compounds of the formula I, but in particular of one or more compounds of the formulae II to XXVIII, mixed with conventional liquid-crystalline materials, leads to a significant improvement in the low-temperature stability without affecting or only slightly affecting the rotational viscosity γ1. The liquid-crystalline media according to the application are also characterised by their relatively high birefringence and their optical stability, and at the same time a broad nematic phase with a low smectic-nematic transition temperature is observed, which increases the storage life. At the same time, the mixtures also exhibit a very low threshold voltage and very good VHR values on exposure to UV.

[0253] The expression "alkyl" or "alkyl*" in the present application includes straight-chain and branched-chain alkyl groups having 1 to 7 carbon atoms, in particular straight-chain groups methyl, ethyl, propyl, butyl, pentyl, hexyl and heptyl. Preference is generally given to groups having 1 to 6 carbon atoms.

[0254] The expression "O-alkyl" in the present application includes straight-chain and branched-chain alkoxy groups.

[0255] The expression "alkenyl" or "alkenyl*" in the present application includes straight-chain and branched-chain alkenyl groups having 2 to 7 carbon atoms, in particular straight-chain groups. Preferred alkenyl groups are C2-C7-1E-alkenyl, C4-C7-3E-alkenyl, C5-C7-4-alkenyl, C6-C7-5-alkenyl and C7-6-alkenyl, in particular C2-C7-1E-alkenyl, C4-C7-3E-alkenyl and C5-C7-4-alkenyl. Examples of particularly preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like. Preference is generally given to groups having up to 5 carbon atoms.

[0256] The expression "fluoroalkyl" in the present application includes straight-chain radicals having at least one fluorine atom, preferably terminal fluorine, i.e. fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl and 7-fluoroheptyl. However, other positions of the fluorine are not excluded.

[0257] The expression "oxaalkyl" or "alkoxy" in the present application includes straight-chain radicals of the formula n H 2n+1 -O-(CH2) m where n and m each, independently of one another, denote 1 to 6. m can also denote 0. Preferably, n = 1 and m = 1 to 6 or m = 0 and n = 1 to 3.

[0258] By suitable selection of the meanings of R 1 and R 2 in formula I, the addressing times, threshold voltages, steepness of the transmission characteristic, etc. can be changed in the desired manner. For example, 1 E-alkenyl, 3 E-alkenyl, 2 E-alkenyloxy, etc. generally lead to shorter addressing times, improved nematic phase tendency and a higher ratio between the elastic constants k 33 (bending) and k 11 (splay) compared with alkyl and alkoxy. 4-alkenyl, 3-alkenyl, etc. generally give lower threshold voltages and lower k 33 / k 11 values compared with alkyl and alkoxy. The mixtures according to the application are distinguished in particular by high K1 values and, as a result, significantly faster response times compared with the mixtures of the prior art.

[0259] The optimum mixing ratio of the compounds of the above-mentioned formulae essentially depends on the desired properties, the selection of the components of the above-mentioned formulae and the selection of any further components which can be present.

[0260] The mixing ratios which are suitable within the ranges mentioned above can easily be determined depending on the case.

[0261] The total amount of the compounds of the above-mentioned formulae in the mixtures according to the application is not critical. Thus, the mixtures can comprise one or more further components in order to optimize various properties. However, the greater the influence observed generally on the desired improvement of the properties of the mixtures, the higher the total concentration of the compounds of the above-mentioned formulae.

[0262] In a particularly preferred embodiment, the medium according to the application comprises compounds of the formulae IV to VIII, wherein X 0represents F, OCF3, OCHF2, OCH=CF2, OCF=CF2, or OCF2-CF2H. The advantageous synergistic effect with the compounds of formula I leads to particularly advantageous properties. In particular, mixtures comprising compounds of formula I and VI, or I and XI, or I and VI and XI are characterized by their low threshold voltage.

[0263] The individual compounds of the above formulae and their subformulae which can be used in the media according to the application are known or can be prepared analogously to known compounds.

[0264] The present application also relates to electro-optical displays, such as TN, STN, TFT, OCB, IPS, PS-IPS, FFS, PS-FFS, positive VA or MLC displays, having two plane-parallel outer plates and said outer plates together with the frame forming a cell, integrated non-linear elements for switching individual pixels on the outer plates, and a nematic liquid-crystal mixture having positive dielectric anisotropy and high resistivity, which is located in the cell, comprising the media of this type, and to the use of these media for electro-optical purposes.

[0265] Furthermore, the mixtures according to the application are also suitable for use in positive VA applications, which also means HT-VA applications. These mean electro-optical displays with in-plane electrode configuration and with positive dielectric anisotropy, which are aligned homeotropically. The mixtures according to the application are particularly preferably suitable for use in TN-TFT display applications with low operating voltage, i.e. particularly preferably for notebook applications.

[0266] The liquid-crystal mixtures according to the application make it possible to achieve a considerable enlargement of the range of parameters obtainable. The combination of the clear points, the viscosities at low temperatures, the stabilities to heat and UV and the high optical anisotropies obtainable are considerably superior to the materials hitherto known in the art.

[0267] The mixtures according to the application are particularly suitable for use in mobile applications and high-Δn TFT applications, such as PDA, notebook, LCD TV and monitors.

[0268] The liquid-crystal mixtures according to the application allow the achievement of rotational viscosities γ1 of ≤ 120 mPa-s, particularly preferably 60 mPa-s, while maintaining a nematic phase down to -20°C and preferably down to -30°C, particularly preferably down to -40°C, and a clear point of ≥ 70°C, preferably ≥ 74°C, thus enabling the achievement of excellent MLC displays with fast response times.

[0269] The dielectric anisotropy Δε of the liquid-crystal mixtures according to the application is preferably ≥ +3, particularly preferably ≥ +4. In addition, the mixtures are characterized by a low operating voltage. The threshold voltage of the liquid-crystal mixtures according to the application is preferably ≤ 2.5 V, particularly ≤ 2.2 V.

[0270] The birefringence Δn of the liquid-crystalline mixture according to the application is preferably > 0.08, particularly preferably > 0.10.

[0271] The nematic phase range of the liquid-crystalline mixture according to the application preferably has a width of at least 90°, in particular at least 100°. The range is preferably at least from -20°C to +70°C.

[0272] If the mixture according to the application is used for IPS or FFS applications, the mixture preferably has a dielectric anisotropy value of 3 to 20 and an optical anisotropy value of 0.07 to 0.13.

[0273] It goes without saying that, by suitable selection of the components of the mixture according to the application, it is also possible to achieve a higher clearing point (for example above 100°C) at a higher threshold voltage or a lower clearing point at a lower threshold voltage and to retain the other advantageous properties. At only slightly increased viscosity accordingly, it is also possible to obtain mixtures with a higher Δε and thus a low threshold. The MLC display according to the application preferably operates at the first Gooch and Tarry transmission minimum [C. H. Gooch and H. A. Tarry, Electron. Lett. 10, 2-4, 1974; C. H. Gooch and H. A. Tarry, Appl. Phys., Vol. 8, 1575-1584, 1975], in which, in addition to particularly advantageous electro-optical properties, for example high steepness of the characteristic line and low angle dependence of the contrast (German patent 30 22 818), a lower dielectric anisotropy is sufficient at the same threshold voltage as in similar displays at the second minimum. This makes it possible to achieve significantly higher resistivity values at the first minimum using the mixtures of the application than in the case of mixtures containing cyano compounds. By suitable selection of the individual components and their weight ratios, the person skilled in the art is able to set the birefringence required for a predetermined layer thickness of the MLC display using simple routine methods.

[0274] The construction of the MLC display according to the application from polariser, electrode substrate and surface-treated electrodes corresponds to the conventional design of such displays. The term "conventional design" is understood here in a broad sense and also includes all derivatives and improved versions of MLC displays, in particular including matrix display elements based on poly-Si TFT or MIM.

[0275] However, a significant difference between the display according to the application and the conventional displays based on twisted nematic cells hitherto consists in the selection of the liquid-crystalline parameters of the liquid-crystalline layer.

[0276] The liquid crystal mixtures which can be used in accordance with the application are prepared in a manner known per se, for example by mixing one or more compounds of the formula I with one or more compounds of the formulae II to XXVII or with other liquid crystal compounds and / or additives. As a rule, the desired number of components which are to be used in smaller amounts is advantageously dissolved in the components which constitute the main constituents at elevated temperature. It is also possible to mix solutions of the components in organic solvents, for example in acetone, chloroform or methanol, and to remove the solvent again, for example by distillation, after thorough mixing.

[0277] The dielectric can also contain other additives known to the person skilled in the art and described in the literature, for example UV stabilizers such as In particular 770, antioxidants, radical scavengers, nanoparticles etc. For example, 0 to 15% of a pleochroic dye or chiral dopant can be added. Suitable stabilizers and dopants are mentioned in Tables C and D below.

[0278] In order to set the desired tilt angle, polymerizable compounds, also called "reactive mesogens", can also be added to the mixtures according to the application. Preferred polymerizable compounds are listed in Table E.

[0279] In the present application and in the examples below, the structures of the liquid crystal compounds are indicated by acronyms and are converted into chemical formulae according to Table A below. All groups C n H 2n+1 and C m H 2m+1 are straight-chain alkyl groups having n and m C atoms, respectively; n, m and k are integers and preferably denote 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 or 12. The coding in Table B is obvious. In Table A, only the acronyms of the parent structures are indicated. In individual cases, the acronyms of the parent structures are followed by the coding of the substituents R 1* , R 2* , L 1* and L 2* separated by a dash.

[0280]

[0281]

[0282] Preferred mixture components are shown in Tables A and B.

[0283] Table A

[0284]

[0285]

[0286]

[0287] Table B

[0288] (n = 1-15; (O)C n H 2n+1 represents C n H 2n+1 or OC n H 2n+1 )

[0289]

[0290]

[0291]

[0292]

[0293]

[0294]

[0295]

[0296]

[0297]

[0298]

[0299] It is particularly preferred that the liquid-crystalline mixture comprises, in addition to the compounds of the formula I, at least one, two, three, four or more compounds from Table B.

[0300] Table C

[0301] Table C shows possible dopants which are usually added to the mixtures according to the application. The mixtures preferably comprise 0 to 10 % by weight, particularly 0.01 to 5 % by weight and particularly preferably 0.01 to 3 % by weight of dopants.

[0302]

[0303]

[0304]

[0305] Table D

[0306] Stabilizers which can be added to the mixtures according to the application, for example, in amounts of 0-10% by weight, are those mentioned below.

[0307]

[0308]

[0309]

[0310]

[0311]

[0312] Table E

[0313] Table E shows exemplary compounds which can be used in LC media according to the application, preferably as reactive mesogenic compounds. If the mixtures according to the application comprise one or more reactive compounds, they are preferably used in amounts of 0.01-5% by weight. It is also possible to add an initiator or a mixture of two or more initiators for the polymerization, if necessary. The initiator or initiator mixture is preferably added in amounts of 0.001-2% by weight, based on the mixture. Suitable initiators are, for example, Irgacure (BASF) or Irganox (BASF).

[0314]

[0315]

[0316]

[0317]

[0318]

[0319]

[0320]

[0321]

[0322]

[0323]

[0324]

[0325] In a preferred embodiment, the mixture according to the present application comprises one or more polymerisable compounds, preferably selected from the group consisting of polymerisable compounds of formulae RM-1 to RM-83. This type of medium is particularly suitable for PS-FFS and PS-IPS applications. Among the reactive mesogens mentioned in Table E, compounds RM-1, RM-2, RM-3, RM-4, RM-5, RM-1 1, RM-17, RM-35, RM-41, RM-61 and RM-80 are particularly preferred. DETAILED DESCRIPTION

[0326] Example

[0327] The following working examples are intended to explain the present application and not to limit the present application.

[0328] In the present context, percentage data represent percent by weight. All temperatures are indicated in degrees Celsius. m.p. means melting point, cl.p. = clearing point. Furthermore, C = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. Data between these symbols indicate the transition temperature, furthermore:

[0329]

[0330] Synthesis Example

[0331] "Conventional work-up" means: if necessary, addition of water, extraction of the mixture with dichloromethane, diethylether, methyl-tert-butylether or toluene, separation of the phases, drying and evaporation of the organic phase, and purification of the product by distillation under reduced pressure, or crystallization, and / or chromatography.

[0332] Example 1:

[0333] The compounds of formula were prepared according to the following schemes:

[0334]

[0335] C 20S B 74N 78I; Δn = 0.057; Δε = -0.82; γ1= 28 mPa-s;

[0336] Analogously the following compounds were prepared:

[0337]

[0338] Mixture Example

[0339] Optical data were measured at the 1st minimum (i.e. at d- An of 0.5 pm) in a TN cell at 20 °C, unless otherwise stated. Optical data were measured at 20 °C, unless otherwise stated. All physical properties were determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals" Status Nov. 1997, Merck KGaA, Germany and were carried out at a temperature of 20 °C, unless otherwise stated.

[0340] Example M1

[0341]

[0342]

[0343] Example M2

[0344]

[0345] Example M3

[0346] To prepare a PS-IPS mixture, 0.25% of compound RM-1

[0347]

[0348] was added to mixture M2.

[0349] Example M4

[0350]

[0351]

[0352] Example M5

[0353] To prepare a PS-FFS mixture, 0.25% of compound RM-1

[0354]

[0355] was added to mixture M4.

[0356] Example M6

[0357]

[0358] Example M7

[0359]

[0360]

[0361] Example M8

[0362] To prepare a PS-FFS mixture, 0.3% of compound RM-41

[0363]

[0364] was added to mixture M7.

[0365] Example M9

[0366]

[0367] Example M10

[0368]

[0369] Example M11

[0370] To prepare a PS-FFS mixture, 0.2% of compound RM-61

[0371]

[0372] was added to mixture M10.

[0373] Example M12

[0374]

[0375]

[0376] Example M13

[0377] To prepare a PS-IPS mixture, 0.25% of compound RM-17

[0378]

[0379] was added to mixture M12.

[0380] Example M14

[0381] To prepare a PS-FFS mixture, 0.2% of compound RM-61

[0382]

[0383] was added to mixture M12.

[0384] Example M15

[0385] To prepare the PS-FFS mixture, 0.3% of compound RM-80

[0386]

[0387] was added to mixture M12.

Claims

1. A liquid-crystalline medium, characterised in that which comprises 2 to 20 % by weight of one or more compounds of the formulae 1-1 to 1-5: which further comprises one or more compounds selected from the group of compounds of the formulae X and / or XI: wherein R 0 represents alkyl or alkoxy having 1 to 6 C atoms, X 0 represents F, mono- or polyfluorinated alkyl or alkoxy having 1 to 6 C atoms, Y 1-4 each, independently from one another, represents H or F, and in formula X and in formula X each, independently of one another, denotes in the formula XI denotes which also comprises one or more compounds selected from the group of compounds of the following formulae: wherein R 3a and R 4a each, independently of one another, denote H, CH3, C2H5or C3H7, and "alkyl" denotes a straight-chain alkyl radical having 1 to 5 C atoms, which comprises one or more compounds of the formulae Ha-1 to Ha-19: wherein the medium comprises 25 to 80 % by weight of compounds of the formulae Ha to Ip and / or Ilia and Illb; wherein the medium comprises CC-3-V in a range of 10 to 50 % 2. Liquid-crystalline medium according to claim 1, characterised in that which further comprises one or more compounds of the formula III: wherein R 3 represents alkenyl having 2 to 9 C atoms, and R 4 This indicates an alkyl or alkoxy group having 1 to 15 carbon atoms. Furthermore, one or more CH2 groups among these groups may be independently linked to each other by -C≡C-, -CF2O-, etc., without direct O atom connections. -O-, -CO-O-, or -O-CO- can be used instead, and one or more H atoms can be replaced by halogens.

3. Liquid-crystalline medium according to any of claims 1 to 2, characterised in that which further comprises one or more compounds selected from the group of compounds of the formulae IV to VIII: wherein R 0 alkyl or alkoxy having 1 to 15 C atoms, in which, in addition, one or more CH2 groups can be replaced, independently of one another, by -C≡C-, -CF2O-, -CH=CH-, -O-, -CO-O-, or -O-CO-, in which, in addition, one or more H atoms can be replaced by halogen, -O-, -CO-O- or -O-CO-, in which, in addition, one or more H atoms can be replaced by halogen, X 0 F, CI, mono- or polyfluorinated alkyl or alkoxy having 1 to 6 C atoms, mono- or polyfluorinated alkenyl or alkenyloxy having 2 to 6 C atoms, Y 1-6 each independently of one another denotes H or F, Z 0 represents -C2H4-, -(CH2)4-, -CH=CH-, -CF=CF-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH2O-, -OCH2-, -COO-, -CF2O- or -OCF2-, in formulae V and VI also a single bond, and r denotes 0 or 1.

4. Liquid-crystalline medium according to any of claims 1 to 2, characterised in that which further comprises one or more compounds selected from the group of compounds of the formulae Va to Vj: wherein R 0 and X 0 have the meaning of claim 3.

5. Liquid-crystalline medium according to any of claims 1 to 2, characterised in that which further comprises one or more compounds selected from the group of compounds of the formulae VI-1a to VI-1d: wherein R 0 and X 0 have the meaning of claim 3.

6. Liquid-crystalline medium according to any of claims 1 to 2, characterised in that which further comprises one or more compounds selected from the group of compounds of the formulae VI-2a to VI-2f: wherein R 0 and X 0 have the meaning of claim 3.

7. Liquid-crystalline medium according to any of claims 1 to 2, characterised in that which further comprises one or more compounds selected from the group of compounds of the formula XII: wherein R 1 and R 2 each independently of one another denotes alkyl, alkenyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyloxy each having up to 9 C atoms.

8. Liquid-crystalline medium according to any of claims 1 to 2, characterised in that which further comprises one or more compounds selected from the group of compounds of the formulae XIII to XVI: wherein R 0 , X 0 , Y 1 and Y 2 have the meaning given in claim 3.

9. Liquid-crystalline medium according to any of claims 1 to 2, characterised in that which further comprises one or more compounds selected from the group of compounds of the following formulae:

10. Liquid-crystalline medium according to any of claims 1 to 2, characterised in that which further comprises one or more compounds selected from the group of compounds of the formulae D1, D2, D3, D4 and D5: wherein Y 1 , Y 2 , R 0 and X 0 have the meaning given in claim 3.

11. Liquid-crystalline medium according to any of claims 1 to 2, characterised in that which further comprises one or more UV stabilizers and / or antioxidants.

12. Liquid-crystalline medium according to any of claims 1 to 2, characterised in that which further comprises one or more polymerizable compounds.

13. Liquid-crystalline medium according to claim 12, characterised in that The polymerizable compounds are selected from the group of RM-1 to RM-83:

14. Process for the preparation of a liquid-crystalline medium according to any of claims 1 to 13, characterised in that one or more compounds of the formulae 1-1 to 1-5 are mixed with at least one further mesogenic compound and, optionally, with one or more additives and / or one or more polymerizable compounds.

15. Use of a liquid-crystalline medium according to any of claims 1 to 13 for optoelectronic purposes.

16. Use of a liquid-crystalline medium according to any of claims 1 to 13 in TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS displays, shutter glasses for 3D effects, LC lenses and positive VA displays.

17. Optoelectronic liquid-crystalline display comprising a liquid-crystalline medium according to any of claims 1 to 13.

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