Liquid crystal medium

Abstract

The invention relates to a liquid-crystalline medium (LC-medium), its use for electro-optical purposes and an LC display containing such a medium.

Description

Technical Field

[0001] The invention relates to a liquid-crystalline medium (LC medium), to its use for electro-optical purposes and to LC displays containing such a medium. Background Art

[0002] Liquid crystals are mainly used as dielectrics in displays, since an applied voltage can affect the optical properties of such materials. Electro-optical devices based on liquid crystals are well known to those skilled in the art and can be based on various effects. Examples of such devices are liquid crystal cells with dynamic scattering, DAP (alignment phase deformation) liquid crystal cells, guest / host liquid crystal cells, TN liquid crystal cells with a "twisted nematic" structure, STN ("super twisted nematic") liquid crystal cells, SBE ("super birefringence effect") liquid crystal cells and OMI (optical mode interference) liquid crystal cells. The most common displays are based on the Schadt-Helfrich effect and have a twisted nematic structure.

[0003] Liquid crystal materials must have good chemical and thermal stability and good stability to electric fields and electromagnetic radiation. In addition, liquid crystal materials should have low viscosity and produce short addressing time, low threshold voltage and high contrast in the liquid crystal cell.

[0004] They should also have a suitable mesophase at normal operating temperatures, i.e. in the widest possible range above and below room temperature, for example a nematic or cholesteric mesophase for the liquid crystal cells mentioned above. Since liquid crystals are usually used as mixtures of several components, it is important that these components are easily miscible with one another. Other properties, such as electrical conductivity, dielectric anisotropy and optical anisotropy must meet different requirements depending on the type of liquid crystal cell and the field of application. For example, the material of a liquid crystal cell with a twisted nematic structure should have positive dielectric anisotropy and low electrical conductivity.

[0005] For example, for matrix liquid crystal displays (MLC displays) with integrated non-linear elements for switching individual pixels, liquid crystal media with a large positive dielectric anisotropy, a broad nematic phase, a relatively low birefringence, a very high specific resistance, good UV and temperature stability and a low vapor pressure are required.

[0006] Matrix liquid crystal displays of this type are known. Examples of non-linear elements which can be used to switch individual pixels are active elements (ie transistors). The term "active matrix" is used hereafter, where two categories can be distinguished:

[0007] 1. MOS (Metal Oxide Semiconductor) or other diodes on a silicon wafer as a substrate.

[0008] 2. Thin film transistors (TFTs) on a glass plate as a substrate.

[0009] The use of single-crystal silicon as substrate material limits the display size, since modular assembly of the various sub-displays creates problems at the joints.

[0010] 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 two technologies: TFTs comprising compound semiconductors, such as CdSe, or TFTs based on polycrystalline or amorphous silicon. The latter technology is being intensively researched worldwide.

[0011] 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. This technology can also be extended to full-color image displays, where a mosaic of red, green and blue filters is arranged in such a way that each filter element is opposite a switchable pixel.

[0012] TFT displays are usually operated in transmissive mode as TN cells with crossed polarizers and are backlit.

[0013] The term "MLC display" encompasses here any matrix display with integrated non-linear elements, ie displays which, in addition to the active matrix, also have passive elements such as varistors or diodes (MIM=metal-insulator-metal).

[0014] MLC displays of this type are particularly suitable for TV applications (e.g. portable televisions) or for high-information displays for computers (notebook computers), and for 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, September 1984: ein 210-288 Matrix LCD Controlled by Double Stage Diode Rings, p. 141 et seq., Paris; STROMER, M., Proc. Eurodisplay 84, September 1984: Design der Thin Film Transistors for Matrix Adressing of Television Liquid Crystal Displays, p. 145 et seq., Paris]. As the resistance decreases, the contrast of MLC displays deteriorates and "afterimage elimination" problems may occur. Since the specific resistance of the liquid crystal mixture usually decreases during the life of the MLC display due to interactions with the inner surfaces of the display, a high (initial) resistance is very important for obtaining an acceptable life. Especially in the case of low-voltage mixtures, it has not been possible to achieve very high specific resistances so far. It is also important that the specific resistance shows as little increase as possible with increasing temperature and after heating and / or UV irradiation. The low-temperature properties of the mixtures of the prior art are also particularly unfavorable. It is required that no crystallization and / or smectic phases appear even at low temperatures and that the temperature dependence of the viscosity is as low as possible. The MLC displays of the prior art therefore do not meet today's requirements.

[0015] In addition to liquid crystal displays that use backlights and therefore operate in a transmissive manner and, if necessary, in a transflective manner, reflective liquid crystal displays are also particularly interesting. These reflective liquid crystal displays use ambient light for information display. They therefore consume significantly less energy than liquid crystal displays with backlight illumination of corresponding size and resolution. Since the TN effect is characterized by very good contrast, this type of reflective display can be viewed well even in bright ambient conditions. Simple reflective TN displays are known, such as those used in watches and portable calculators. However, this principle can also be used for high-quality, relatively high-resolution active matrix addressing displays, such as TFT displays. Here, as is known in the case of ordinary transmissive TFT-TN displays, liquid crystals with low birefringence (Δn) must be used to achieve low optical delay (d·Δn). This low optical delay leads to a generally acceptable low viewing angle dependence of contrast (see DE 30 22 818). In the case of reflective displays, the use of liquid crystals with low birefringence is more important than in the case of transmissive displays, because the effective layer thickness through which light passes is almost twice as large in reflective displays as in transmissive displays with the same layer thickness.

[0016] In order to realize the 3D effect by means of shutter glasses, fast-switching mixtures with low rotational viscosity and correspondingly high optical anisotropy (Δn) are used in particular. Mixtures with high optical anisotropy (Δn) can be used to realize electro-optical lens systems which can be used to convert a two-dimensional presentation of a display into a three-dimensional autostereoscopic presentation.

[0017] There is therefore still a great need for MLC displays having a very high specific resistance which do not exhibit these disadvantages or exhibit them only to a lower extent and which simultaneously have a large operating temperature range, short response times (even at low temperatures) and a low threshold voltage.

[0018] In the case of a TN (Schadt-Helfrich) liquid crystal cell, a liquid crystal medium is required that can achieve the following advantages in the liquid crystal cell:

[0019] - Extended nematic phase range (especially down to low temperatures)

[0020] -Switching capability at extremely low temperatures (outdoor applications, automotive, avionics)

[0021] - Improved resistance to UV radiation (longer life)

[0022] -Low threshold voltage.

[0023] The liquid crystal media available in the prior art do not make it possible to achieve these advantages while maintaining the other parameters at the same time. Modern LCD flat-panel image screens always require faster response times in order to be able to reproduce multimedia contents such as movies and video games realistically. This in turn requires nematic liquid crystal mixtures with very low rotational viscosities γ1 and high optical anisotropies Δn. In order to obtain the required rotational viscosities, substances are sought which have a particularly favorable γ1 / clearing point ratio in combination with a high Δn and a high polarity.

[0024] In the case of super-twisted (STN) liquid crystal cells, liquid crystal media are required which allow greater multiplexing and / or lower threshold voltages and / or a wider nematic phase range, in particular at low temperatures. For this purpose, there is an urgent need to further broaden the usable parameter range (clearing point, smectic-nematic transition or melting point, viscosity, dielectric parameters, elastic parameters).

[0025] Particularly in the case of LC displays for TV and video applications (e.g. LCD TVs, monitors, PDAs, notebook computers, game consoles), the response times need to be significantly reduced. This requires LC mixtures with low rotational viscosity and high dielectric anisotropy. At the same time, the liquid-crystalline media should have high-definition highlights. Summary of the invention

[0026] It was an object of the present invention to provide liquid-crystalline media, in particular for MLC, TN, PS-TN, STN, ECB, OCB, IPS, PS-IPS, FFS, PS-FFS or positive VA displays of this type, which do not have the disadvantages mentioned above or have them only to a lesser extent and which preferably have fast response times and low rotational viscosities and at the same time high bright spots, as well as high dielectric anisotropy and low threshold voltages.

[0027] It has now been found that this object can be achieved if liquid-crystalline media as described below are used.

[0028] The invention provides a liquid crystal (LC) medium, characterised in that it has a positive dielectric anisotropy and comprises one or more compounds of the formula IA and one or more compounds of the formula IB

[0029]

[0030] Where R 1 and R 2 in each case independently of one another means alkyl, alkoxy, oxaalkyl or fluoroalkyl, in each case having 1 to 8 C atoms,

[0031] and wherein the liquid crystal medium does not contain a group R selected from 1 and R 2 has the above meanings and wherein in addition one or two radicals R 1or R 2 Compounds of formula IA and IB containing a C=C double bond.

[0032] The liquid-crystalline media according to the invention preferably comprise no compounds containing C═C double bonds, with the exception of C═C double bonds as constituent parts of polymerizable groups or of aromatic or unsaturated rings.

[0033] The invention also provides for the use of the liquid-crystal mixtures according to the invention as described above and below in electro-optical displays, in particular liquid-crystal displays, preferably in TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS, positive-VA and PS-positive-VA displays and in liquid-crystal windows and shutter glasses, in particular for 3D applications.

[0034] The invention also provides an electro-optical display, in particular a liquid-crystal display, preferably of the TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS, positive-VA or positive-PS-VA type, a liquid-crystal window or shutter glasses for 3D applications, which contains a liquid-crystal medium according to the invention.

[0035] Surprisingly, it has been found that the liquid crystal media according to the invention have a high dielectric anisotropy Δε, a high birefringence Δn, a low rotational viscosity γ1 and simultaneously high VHR values ​​and good low temperature stability. They are therefore particularly suitable for use in monitors, notebook computers and multimedia devices.

[0036] The following meanings apply above and below:

[0037] The term "mesogenic group" is known to the person skilled in the art and is described in the literature and refers to a group which, due to the anisotropy of its attractive and repulsive interactions, makes a major contribution to the realization of liquid crystal (LC) phases in low molecular weight or polymeric substances. Compounds containing mesogenic groups (mesogenic compounds) do not necessarily have to have LC phases themselves. It is also possible that mesogenic compounds only exhibit LC phase behavior after mixing with other compounds and / or after polymerization. Typical mesogenic groups are, for example, rigid small rod-shaped or small disk-shaped units. An overview of the terms and definitions used in connection with mesogenic or LC compounds can be found in Pure Appl. Chem. 2001, 73 (5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368.

[0038] The term "spacer" ("spacer group"), also referred to above and below as "Sp", is known to the person skilled in the art and is described in the literature, see for example Pure Appl. Chem. 2001, 73 (5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368. Unless otherwise indicated, the term "spacer group" or "spacer" refers above and below to a flexible group which connects the mesogenic group and the polymerizable group in the polymerizable mesogenic compound to each other.

[0039] The term "reactive mesogen" or "RM" refers to a compound containing a mesogenic group and one or more functional groups suitable for polymerization (also called polymerizable group or group P).

[0040] The terms "low molecular weight compounds" and "non-polymerizable compounds" refer to compounds, generally monomeric, which do not contain functional groups suitable for polymerization under the usual conditions known to those skilled in the art, in particular under the conditions for the polymerization of RMs.

[0041] Unless otherwise specified, the term "polymerizable compound" refers to a monomeric polymerizable compound.

[0042] In the above and below, in each case refers to the trans-1,4-cyclohexylene ring, and It refers to a 1,4-phenylene ring.

[0043] In the formulae above and below, alkyl or alkoxy may be straight-chain or branched. It is preferably straight-chain, has 2, 3, 4, 5, 6 or 7 C atoms and accordingly preferably refers to ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy, furthermore methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy or tetradecyloxy.

[0044] Oxaalkyl preferably denotes straight-chain 2-oxapropyl (=methoxymethyl), 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-oxanononyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl.

[0045] If the alkyl group is at least monosubstituted by halogen, this group is preferably straight-chain and the halogen is preferably F or Cl. In the case of polysubstitution, the halogen is preferably F. The resulting groups also include perfluorinated groups. In the case of monosubstitution, the fluorine or chlorine substituent can be in any desired position, but is preferably in the ω-position.

[0046] In the above and below formulae, X 0 Preferably it is F, Cl or a mono- or polyfluorinated alkyl or alkoxy radical having 1, 2 or 3 C atoms, or a mono- or polyfluorinated alkenyl radical having 2 or 3 C atoms. 0 Particularly preferred are F, Cl, CF3, CHF2, OCF3, OCHF2, OCFHCF3, OCFHCHF2, OCFHCHF2, OCF2CH3, OCF2CHF2, OCF2CHF2, OCF2CF2CHF2, OCF2CF2CHF2, OCFHCF2CF3, OCFHCF2CHF2, OCF2CF2CF3, OCF2CF2CClF2, OCC1FCF2CF3, OCH═CF2 or CH═CF2, very particularly preferably F or OCF3, furthermore CF3, OCF═CF2, OCHF2 and OCH═CF2.

[0047] The term "Alkyl" or "Alkyl*" in the present application preferably includes straight-chain and branched alkyl radicals having 1 to 6 carbon atoms, in particular the straight-chain radicals methyl, ethyl, propyl, butyl, pentyl and hexyl. Radicals having 2 to 5 carbon atoms are generally preferred.

[0048] The term "fluoroalkyl" preferably includes straight-chain groups with terminal fluorine, i.e. fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl and 7-fluoroheptyl. However, other positions of fluorine are not excluded.

[0049] The term "oxaalkyl" or "alkoxy" preferably includes groups of formula C n H 2n+1 -O-(CH2) m wherein n and m in each case independently of one another represent an integer from 1 to 6. m may also represent 0. Preferably, n=1 and m is 1-6 or m=0 and n=1 to 3.

[0050] The compound of formula IA is preferably selected from the following sub-formulae:

[0051]

[0052] where the individual radicals, in each case independently of one another and identically or differently on each occurrence, have the following meanings

[0053] alkyl, alkyl* straight-chain alkyl having 1 to 6 C atoms, in particular ethyl, propyl, butyl or pentyl,

[0054] Alkoxy is a straight-chain alkoxy group having 1 to 6 C atoms, in particular methoxy, ethoxy or propoxy.

[0055] Particularly preferred compounds of formula IA and its subformulae are selected from the following

[0056]

[0057] In a preferred embodiment, the liquid crystal medium according to the invention comprises one or more compounds of the formula IA, preferably selected from the formulae IA1 and IA2, particularly preferably selected from the formulae IA1a, IA1b and IA2a, very particularly preferably the formulae IA1a and / or IA1b. The individual concentration of each of these compounds is preferably in each case 3 to 25% by weight, particularly preferably 5 to 20% by weight. The total concentration of these compounds is preferably 10 to 50% by weight, particularly preferably 15 to 40% by weight.

[0058] The compound of formula IB is preferably selected from the following sub-formulae:

[0059]

[0060] wherein "alkyl" and "alkoxy" have the meanings given in formula IA2.

[0061] Particularly preferred compounds of formula IB and IB1 are selected from the following

[0062]

[0063] In a preferred embodiment, the liquid-crystalline medium according to the invention comprises one or more compounds of the formula IB, preferably selected from the formula IB1, particularly preferably selected from the formula IB1a and IB1b, very particularly preferably the formula IB1a. The individual concentration of each of these compounds is preferably in each case 3 to 25% by weight, particularly preferably 8 to 20% by weight. The total concentration of these compounds is preferably 5 to 30% by weight, particularly preferably 8 to 25% by weight.

[0064] In a preferred embodiment, the liquid-crystalline media according to the invention comprise one or more compounds of the formula IA, preferably of the formula IA1, very particularly preferably of the formula IA1a and / or of the formula IA1b, and one or more compounds of the formula IB, preferably of the formula IB1, very particularly preferably of the formula IB1a.

[0065] In a further preferred embodiment, the liquid-crystalline media according to the invention comprise one or more stabilizers.

[0066] Preferably the stabilizer is selected from the following formula

[0067]

[0068]

[0069] where the individual radicals, in each case independently of one another and identically or differently on each occurrence, have the following meanings

[0070] R a-d straight-chain or branched alkyl radical having 1 to 10 C atoms, preferably having 1 to 6 C atoms, particularly preferably having 1 to 4 C atoms, very particularly preferably methyl,

[0071] X S H, CH3, OH or O ● ,

[0072] A S linear, branched or cyclic alkylene having 1 to 20 C atoms, which is optionally substituted,

[0073] n is an integer from 1 to 6, preferably 3.

[0074] Particularly preferred stabilizers of formula S3 are selected from the group consisting of formula S3A

[0075]

[0076] wherein n2 is an integer from 1 to 12, and wherein the group (CH2) n2 One or more H atoms in the group are optionally replaced by methyl, ethyl, propyl, butyl, pentyl or hexyl.

[0077] Very particularly preferred stabilizers are selected from the group consisting of

[0078]

[0079]

[0080]

[0081] In a particularly preferred embodiment, the liquid-crystalline media according to the invention comprise one or more stabilizers selected from the group consisting of formulae S1-1, S2-1, S3-1, S3-1, S3-3 and S4-1.

[0082] In a further preferred embodiment, the liquid-crystalline media according to the invention comprise one or more stabilizers selected from Table D below.

[0083] The concentration of the stabilizers, in particular those of the formulae S1 to S3 and subformulae thereof and those from Table D, in the liquid-crystalline media according to the invention is preferably from 10 to 500 ppm, particularly preferably from 20 to 100 ppm.

[0084] Further preferred embodiments of the liquid crystal medium according to the present invention are given below:

[0085] - the liquid-crystalline medium further comprises one or more compounds selected from the following formulae:

[0086]

[0087] where the individual radicals, in each case independently of one another and identically or differently on each occurrence, have the following meanings

[0088]

[0089] R 0 unsubstituted or halogenated alkyl or alkoxy radicals having 1 to 15 C atoms, wherein, in addition, one or more CH2 radicals in these radicals may in each case independently of one another be replaced by -CF2O-, -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly attached to each other,

[0090] X 0 F, Cl, haloalkyl, haloalkoxy or haloalkenyloxy, each having up to 6 C atoms,

[0091] Y 1-6 H or F,

[0092] Y 0 H or CH3.

[0093] Preferred compounds of formula II and III are those wherein Y 0 Those that refer to H.

[0094] Further preferred compounds of formula II and III are those wherein R 0 refers to an alkyl group having 1 to 6 C atoms, preferably ethyl or propyl, and X 0 Those referring to F or OCF3, preferably F.

[0095] - the liquid-crystalline medium further comprises one or more compounds selected from the following formulae:

[0096]

[0097]

[0098] Where R 0 and X 0 has the meaning given in formula II or one of the preferred meanings given above and below.

[0099] Preferred compounds are those of the formulae III, II2 and II3, particular preference being given to those of the formulae III and II2.

[0100] In the compounds of formulae II1 to II7, R 0 Preferably, X is an alkyl radical having 1 to 6 C atoms, particularly preferably an ethyl radical or a propyl radical. 0 Preferably, it refers to F or OCF3, and F is particularly preferred.

[0101] The liquid crystal medium comprises one or more compounds of formula II or a subformula thereof, in which Y 0 The liquid-crystalline medium preferably comprises one or more compounds of the formula II selected from the following subformulae:

[0102]

[0103]

[0104] Where R 0 and X 0 has the meaning given in formula II or one of the preferred meanings given above and below.

[0105] Preferred compounds are those of the formulae IIA1, IIA2 and IIA3, those of the formulae IIA1 and IIA2 being particularly preferred.

[0106] In the compounds of Formulae IIA1 to IIA7, R 0 Preferably, X is an alkyl radical having 1 to 6 C atoms, particularly preferably an ethyl radical or a propyl radical. 0 Preferably, it refers to F or OCF3, and F is particularly preferred.

[0107] The liquid-crystalline medium comprises one or more compounds of formula III selected from the following subformulae:

[0108]

[0109]

[0110]

[0111]

[0112] Where R 0 and X 0 has the meaning given in formula II or one of the preferred meanings given above and below.

[0113] Preferred compounds are those of formula III1, III4, III6, III16, III19 and III20.

[0114] In the compounds of formula III1 to III21, R 0 X is preferably an alkyl radical having 1 to 6 C atoms, particularly preferably an ethyl radical or a propyl radical. 0 Preferably, it refers to F or OCF3, particularly preferably F, and Y 2 Preferably it refers to F.

[0115] The liquid-crystalline medium comprises one or more compounds of the formula III or its subformulae as described above and below, in which Y 0 =CH3. The liquid-crystalline medium preferably comprises one or more compounds of the formula III selected from the following subformulae:

[0116]

[0117]

[0118]

[0119]

[0120]

[0121] Where R 0 and X 0 has the meaning given in formula III or one of the meanings given above and below.

[0122] Preferred compounds are those of formula IIIA1, IIIA4, IIIA6, IIIA16, IIIA19 and IIIA20.

[0123] In the compounds of formulae IIIA1 to IIIA21, R 0 X is preferably an alkyl radical having 1 to 6 C atoms, particularly preferably an ethyl radical or a propyl radical. 0 Preferably, it refers to F or OCF3, particularly preferably F, and Y 2 Preferably it refers to F.

[0124] - the liquid-crystalline medium further comprises one or more compounds selected from the following formulae:

[0125]

[0126] Where R 0 , X 0 and Y 1-4 has the meaning given above, and

[0127] Z 0refers to -C2H4-, -(CH2)4-, -CH=CH-, -CF=CF-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH2O-, -OCH2-, -COO- or -OCF2-, and also refers to a single bond in formulas V and VI, and also refers to -CF2O- in formulas V and VIII,

[0128] r is 0 or 1, and

[0129] s refers to 0 or 1;

[0130] - The compound of formula IV is preferably selected from the following formulae:

[0131]

[0132] Where R 0 and X 0 has the meaning given above.

[0133] R 0 Preferably, X is an alkyl radical having 1 to 6 C atoms. 0 Preferably it means F or OCF3, furthermore OCF=CF2 or Cl;

[0134] - The compound of formula IVa is preferably selected from the following sub-formulae:

[0135]

[0136] Where R 0 has the meaning given above and preferably refers to propyl or pentyl.

[0137] - The compound of formula IVc is preferably selected from the following sub-formulae:

[0138]

[0139] Where R 0 has the meaning given above and preferably refers to pentyl or amyl.

[0140] The compound of the formula IVc, in particular of the formula IVc1, is preferably present in the liquid-crystalline media according to the invention in a concentration of 1 to 20% by weight, particularly preferably 2 to 15% by weight.

[0141] - The compounds of formula V are preferably selected from the following sub-formulae:

[0142]

[0143]

[0144] Where R 0 and X 0 has the meaning given above.

[0145] R 0 Preferably, X is an alkyl radical having 1 to 6 C atoms. 0 Preference is given to F and OCF3, furthermore OCHF2, CF3, OCF=CF2 and OCH=CF2.

[0146] The liquid-crystalline media according to the invention particularly preferably comprise one or more compounds of the formula Va1,

[0147]

[0148] Here, "alkyl" has the meaning given for formula IA1 and preferably denotes ethyl, propyl or pentyl, very particularly preferably propyl.

[0149] - The compound of formula VI is preferably selected from the following sub-formulae:

[0150]

[0151]

[0152] Where R 0 and X 0 has the meaning given above.

[0153] R 0 Preferably, X is an alkyl radical having 1 to 6 C atoms. 0 Preference is given to F, and furthermore to OCF3, CF3, CF=CF2, OCHF2 and OCH=CF2.

[0154] The liquid-crystalline media according to the invention particularly preferably comprise one or more compounds of the formula VIb1 and / or VIe1,

[0155]

[0156] Here, "alkyl" has the meaning given for formula IA1 and preferably denotes ethyl, propyl or pentyl, very particularly preferably propyl.

[0157] - The compound of formula VII is preferably selected from the following sub-formulae:

[0158]

[0159] Where R 0 and X 0 has the meaning given above.

[0160] R 0 Preferably, X is an alkyl radical having 1 to 6 C atoms. 0 Preference is given to F, and furthermore to OCF3, OCHF2 and OCH═CF2.

[0161] - the liquid-crystalline medium further comprises one or more compounds of the following formulae:

[0162]

[0163] Where R 0 , X 0 and Y 1-4 has in each case, independently of one another, one of the meanings given above. 0 Preferably, it is F, Cl, CF3, OCF3 or OCHF2. 0 Preference is given to alkyl, alkoxy, oxaalkyl or fluoroalkyl, in each case having 1 to 6 C atoms.

[0164] The liquid-crystalline media according to the invention particularly preferably comprise one or more compounds of the formula IXa,

[0165]

[0166] Where R 0 has the meaning given above. 0 Preferably it is straight-chain alkyl, in particular ethyl, n-propyl, n-butyl or n-pentyl, particularly preferably n-propyl.

[0167] The compound of the formula IX, in particular of the formula IXa, is preferably present in the liquid-crystalline media according to the invention in a concentration of 1 to 15% by weight, particularly preferably 2 to 10% by weight.

[0168] - the liquid-crystalline medium additionally comprises one or more compounds of the formula X:

[0169]

[0170] Where R 0 , X 0 , Y 1 and Y 2 has the meaning given above, and R 0 Preference is given to alkyl radicals having 1 to 6 C atoms.

[0171] The liquid-crystalline media according to the invention particularly preferably comprise one or more compounds of the formula Xa,

[0172]

[0173] Here, "alkyl" has the meaning given for formula IA1 and preferably denotes ethyl, propyl or pentyl, very particularly preferably propyl.

[0174] The compound of the formula X, in particular of the formula Xa, is preferably present in the liquid-crystalline media according to the invention in a concentration of 0.5 to 10% by weight, particularly preferably 1 to 5% by weight.

[0175] - the liquid-crystalline medium further comprises one or more compounds of the following formulae:

[0176]

[0177] Where R 0 and Y 2-4 has in each case, independently of one another, one of the meanings given above. 0 Preference is given to alkyl, alkoxy, oxaalkyl or fluoroalkyl, in each case with a maximum of 6 C atoms.

[0178] The liquid-crystalline media according to the invention particularly preferably comprise one or more compounds of the formula XIa,

[0179]

[0180] Where R 0 has the meaning given above. 0 Preferably it is straight-chain alkyl, in particular ethyl, n-propyl, n-butyl or n-pentyl, particularly preferably n-propyl.

[0181] The compound of the formula XI, in particular of the formula XIa, is preferably present in the liquid-crystalline media according to the invention in a concentration of 1 to 30% by weight, particularly preferably 2 to 25% by weight and very particularly preferably 2 to 15% by weight.

[0182] - the liquid-crystalline medium further comprises one or more compounds of the formula XII:

[0183]

[0184] Where R 1 and R 2 has the meanings given in the formula IA and preferably refers to alkyl having 1 to 6 C atoms.

[0185] - the liquid-crystalline medium further comprises one or more compounds selected from the following formulae:

[0186]

[0187]

[0188] Where R 1 and R 2 has the meaning given in formula IA, and L is H or F. R 1 and R 2 Preferably, these are in each case independently of one another, alkyl or alkoxy radicals having 1 to 6 C atoms.

[0189] The liquid-crystalline media according to the invention particularly preferably comprise one or more compounds of the formula XIVa

[0190]

[0191] Therein, "alkyl" and "alkyl*" have in each case, independently of one another, the meanings given for formula IA1 and preferably denote ethyl, propyl or pentyl, very particularly preferably ethyl or propyl.

[0192] - the liquid-crystalline medium additionally comprises one or more compounds of the formula XVI,

[0193]

[0194] where Y 1 , Y 2 , R 1 and R 2 has the meaning given above.

[0195] Particularly preferred compounds of formula XVI are those selected from the following sub-formulae:

[0196]

[0197] Here, "alkyl" and "alkyl*" have the meanings given in formula IA1 and preferably denote ethyl, propyl or pentyl.

[0198] Preferred are compounds of formula XVIb. Particularly preferred are compounds selected from the group consisting of

[0199]

[0200] Particularly preferred are compounds of the formulae XVIb1, XVIb2 and XVIb3.

[0201] The compound of the formula XVI, in particular of the formula XVIb, is preferably present in the liquid-crystalline media according to the invention in a concentration of 2 to 30% by weight, particularly preferably 2 to 25% by weight.

[0202] - the liquid-crystalline medium comprises one or more compounds selected from the following formulae:

[0203]

[0204]

[0205] Among them, L, R 1 and R 2 has the meaning given above and R 1 and R 2Preferably, independently of one another, it is in each case an alkyl radical having 1 to 6 C atoms. Particular preference is given to compounds of the formula XVII1 in which L is F. Particular preference is given to compounds of the formula XVII2 in which L is F.

[0206] - the liquid-crystalline medium further comprises one or more compounds selected from the following formulae:

[0207]

[0208]

[0209] Where R 0 and X 0 has in each case independently of one another one of the meanings given above and Y 1-4 In each case, independently of one another, X refers to H or F. 0 Preferably, it is F, Cl, CF3, OCF3 or OCHF2. 0 Preference is given to alkyl, alkoxy, oxaalkyl or fluoroalkyl, in each case having 1 to 6 C atoms.

[0210] The liquid-crystalline medium particularly preferably comprises one or more compounds of the formula XXa,

[0211]

[0212] Where R 0 has the meaning given above. 0 Preferably it is straight-chain alkyl, in particular ethyl, n-propyl, n-butyl or n-pentyl, particularly preferably n-propyl.

[0213] The compound of the formula XX, in particular of the formula XXa, is preferably present in the liquid-crystalline media according to the invention in a concentration of 1 to 15% by weight, particularly preferably 2 to 10% by weight.

[0214] The liquid-crystalline media according to the invention particularly preferably comprise one or more compounds of the formula XXIa,

[0215]

[0216] Where R 0 has the meaning given above. 0 Preferably it is straight-chain alkyl, in particular ethyl, n-propyl, n-butyl or n-pentyl, particularly preferably n-propyl.

[0217] The compound of the formula XXI, in particular of the formula XXIa, is preferably present in the medium according to the invention in a concentration of 1 to 15% by weight, particularly preferably 2 to 10% by weight.

[0218] The liquid-crystalline media according to the invention particularly preferably comprise one or more compounds of the formula XXIIIa,

[0219]

[0220] Where R 0 has the meaning given above. 0 Preferably it is straight-chain alkyl, in particular ethyl, n-propyl, n-butyl or n-pentyl, particularly preferably n-propyl.

[0221] The compound of the formula XXIII, in particular of the formula XXIIIa, is preferably present in the liquid-crystalline media according to the invention in a concentration of 0.5 to 5% by weight, particularly preferably 0.5 to 2% by weight.

[0222] - the liquid-crystalline medium additionally comprises one or more compounds of the formula XXIV,

[0223]

[0224] Where R 0 and Y 1-6 has the meaning given above, s means 0 or 1, X 0 has the meaning given above or refers to an alkyl or alkoxy radical having 1 to 6 C atoms, preferably straight-chain, and

[0225] means

[0226] R 0 Preferably, X is an alkyl radical having 1 to 6 C atoms. 0 Preferably refers to F;

[0227] - The compound of formula XXIV is preferably selected from the following sub-formulae:

[0228]

[0229]

[0230] Where R 0 , X 0 and Y 1 has the meaning given above. 0 Preferably, X is an alkyl radical having 1 to 6 C atoms. 0 Preferably, F is 1 Preferably refers to F;

[0231] Preferably

[0232]

[0233] -R 0 is a straight-chain alkyl or alkenyl group having 2 to 6 C atoms;

[0234] - the liquid-crystalline medium further comprises one or more compounds selected from the following formulae:

[0235]

[0236] Where R 1 and X 0 has the meaning given above. 1 Preferably, X is an alkyl radical having 1 to 6 C atoms. 0 Preferably, it is F or Cl. In formula XXIV, X 0 Preferably it refers to Cl.

[0237] - the liquid-crystalline medium further comprises one or more compounds selected from the following formulae:

[0238]

[0239]

[0240] Where R 1 and X 0 has the meaning given above. 1 Preferably, X is an alkyl radical having 1 to 6 C atoms. 0 Preferably it refers to F.

[0241] The liquid-crystalline medium preferably comprises one or more compounds of the formula XXIX, in which X 0 It means F.

[0242] The compounds of the formulae XXVI to XXIX are preferably present in the liquid-crystalline media according to the invention in a concentration of 1 to 20% by weight, particularly preferably 1 to 15% by weight.

[0243] The liquid-crystalline medium preferably comprises at least one compound of the formula XXIX.

[0244] The liquid-crystalline media according to the invention particularly preferably comprise one or more compounds of the formula XXIXa,

[0245]

[0246] Where R 1 has the meaning given above. 1 Preferably it is straight-chain alkyl, in particular ethyl, n-propyl, n-butyl or n-pentyl, particularly preferably n-propyl.

[0247] The compound of the formula XXIX, in particular of the formula XXIXa, is preferably present in the liquid-crystalline media according to the invention in a concentration of 1 to 15% by weight, particularly preferably 2 to 10% by weight.

[0248] - the liquid-crystalline medium further comprises one or more compounds selected from the following formulae

[0249]

[0250]

[0251] Where R 1 and X 0 has the meaning given above. 1 Preferably, X is an alkyl radical having 1 to 6 C atoms. 0 Preferably it refers to F.

[0252] The liquid-crystalline medium preferably comprises one or more compounds of the formula XXX1, in which X 0 It means F.

[0253] The compounds of the formulae XXX1 to XXX3 are preferably present in the liquid-crystalline media according to the invention in a concentration of 1 to 20% by weight, particularly preferably 1 to 15% by weight.

[0254] The liquid-crystalline media according to the invention do not contain any 1 and / or R 2 refers to a compound of the formula IA or IB having an alkenyl, alkenyloxy, oxaalkenyl or fluoroalkenyl group with 1 to 8 C atoms. The liquid-crystalline media according to the invention preferably do not contain 1 and / or R 2 refers to a compound of formula IA or IB containing an optionally fluorinated alkyl, alkoxy or oxaalkyl group containing a C=C double bond.

[0255] In a particularly preferred embodiment, the liquid-crystalline media according to the invention do not contain any compounds selected from the following formulae, in which L, R 1 and R 2 has the meaning given above and in which the radical R 1 and R 2 At least one of the

[0256]

[0257]

[0258] Further preferred media are selected from the following preferred embodiments, including all subcombinations thereof:

[0259] - The liquid crystal medium contains one or more compounds of formula II, preferably selected from formula III, II2 and II3, particularly preferably selected from formula III and II2. The individual concentration of each of these compounds is preferably 2 to 15% by weight. The total concentration of these compounds is preferably 5 to 45% by weight.

[0260] - The liquid crystal medium contains one or more compounds of formula III, preferably selected from formula III1, III4, III6, III16, III19 and III20, particularly preferably selected from formula III1, III6, III16 and III20. The individual concentration of each of these compounds is preferably 2 to 15% by weight. The total concentration of these compounds is preferably 5 to 30% by weight.

[0261] The liquid crystal medium comprises one or more compounds of the formula IV, preferably selected from the formula IVa or IVc, particularly preferably selected from the formula IVa1 or IVc1, very particularly preferably the formula IVc1. The individual concentration of each of these compounds is preferably 2 to 15% by weight. The total concentration of these compounds is preferably 5 to 20% by weight.

[0262] The liquid crystal medium comprises one or more compounds of the formula V, particularly preferably compounds of the formula Va, very particularly preferably compounds of the formula Va1. The individual concentration of each of these compounds is preferably 1 to 20% by weight. The total concentration of these compounds is preferably 5 to 20% by weight.

[0263] The liquid crystal medium comprises one or more compounds of the formula VI, particularly preferably selected from the formulae VIb and VIe, very particularly preferably selected from the formulae VIb1 and VIe1. The individual concentration of each of these compounds is preferably 1 to 20% by weight. The total concentration of these compounds is preferably 5 to 20% by weight.

[0264] The liquid-crystalline medium comprises one or more compounds of the formula XIII, particularly preferably compounds of the formula XIIIa. The total concentration of these compounds is preferably from 1 to 20% by weight.

[0265] The liquid crystal medium comprises one or more compounds of the formula XIV, particularly preferably compounds of the formula XIVa. The individual concentration of each of these compounds is preferably 2 to 15% by weight. The total concentration of these compounds is preferably 5 to 20% by weight.

[0266] The liquid crystal medium comprises one or more compounds of the formula X, particularly preferably compounds of the formula Xa. The individual concentration of each of these compounds is preferably 1 to 10% by weight. The total concentration of these compounds is preferably 2 to 15% by weight.

[0267] - The liquid crystal medium comprises one or more compounds of the formula XI, particularly preferably compounds of the formula XIa. The individual concentration of each of these compounds is preferably 5 to 25% by weight. The total concentration of these compounds is preferably 10 to 35% by weight.

[0268] The liquid crystal medium comprises one or more compounds of the formula XVIb, particularly preferably selected from the formulae XVIb1, XVIb2 and XVIb3. The individual concentration of each of these compounds is preferably 2 to 15% by weight. The total concentration of these compounds is preferably 10 to 35% by weight.

[0269] The liquid crystal medium comprises one or more compounds of the formula XVIc, particularly preferably selected from the formulae XVIc1, XVIc2 and XVIc3. The individual concentration of each of these compounds is preferably 2 to 10% by weight. The total concentration of these compounds is preferably 5 to 20% by weight.

[0270] The liquid crystal medium comprises one or more compounds selected from the formulae XVII1, XVII2 and XVII3, particularly preferably compounds of the formula XVII1 in which L is F and / or compounds of the formula XVII2 in which L is F. The individual concentration of each of these compounds is preferably 1 to 8% by weight. The total concentration of these compounds is preferably 2 to 10% by weight.

[0271] The liquid crystal medium comprises one or more compounds of the formula XX, particularly preferably compounds of the formula XXa. The individual concentration of each of these compounds is preferably 2 to 10% by weight. The total concentration of these compounds is preferably 2 to 20% by weight.

[0272] The liquid crystal medium comprises one or more compounds of the formula XXI, particularly preferably compounds of the formula XXIa. The individual concentration of each of these compounds is preferably 2 to 10% by weight. The total concentration of these compounds is preferably 3 to 15% by weight.

[0273] The liquid-crystalline medium comprises one or more compounds of the formula XXIII, particularly preferably compounds of the formula XXIIIa. The concentration of these compounds is preferably from 0.5 to 5% by weight.

[0274] The liquid-crystalline medium comprises one or more compounds of the formula XXIX, particularly preferably compounds of the formula XXIXa. The concentration of these compounds is preferably from 2 to 10% by weight.

[0275] - the liquid-crystalline medium comprises one or more compounds of the formula IA, one or more compounds of the formula IB, one or more compounds selected from the formulae II and III or subformulae thereof, preferably selected from the formulae III, II, II, III, III, III, III, III, III, III and ...

[0276] The concentration of the compounds of the formulae II-XI and XVIII-XXX3 in the liquid-crystalline media according to the invention is from 30 to 60% by weight.

[0277] The concentration of the compound of the formulae XII to XVII3 in the liquid-crystalline media according to the invention is from 2 to 30% by weight.

[0278] It has been found that the use of liquid-crystalline media according to the invention comprising one or more compounds of the formulae IA and IB mixed with conventional liquid-crystalline materials, in particular with one or more compounds of the formulae II to XXX3, and free of alkenyl compounds, leads to a significant increase in the photostability and relatively high values ​​of the birefringence, while a broad nematic phase with a low smectic-nematic transition temperature is observed, thereby improving the storage stability. At the same time, the mixture exhibits very low threshold voltages and very good VHR values ​​on UV irradiation, and very high clearing points.

[0279] The compounds of formulae IA to XXX3 have a wide range of applications. Depending on the choice of substituents, they can serve as base materials for forming the main part of liquid-crystalline media; however, it is also possible to add additional liquid-crystalline base materials from other compound classes to the compounds of formulae IA to XXX3, for example, in order to influence the dielectric anisotropy and / or optical anisotropy of this type of dielectric and / or to optimize its threshold voltage and / or its viscosity.

[0280] By properly choosing R 0 and X 0 In the sense of , it is possible to vary the addressing time, the threshold voltage, the steepness of the transmission characteristic line, etc. in a desired manner. The mixtures according to the invention are characterized in particular by high Δε values ​​and therefore have significantly faster response times compared to the mixtures of the prior art.

[0281] In a particularly preferred embodiment, the media according to the invention comprise compounds of the formulae II to VIII (preferably II, III, V and VI), in which X 0 It refers to F, OCF3, OCHF2, OCH=CF2, OCF=CF2 or OCF2-CF2H, and F or OCF3 is particularly preferred.

[0282] The compounds of the formulae IA to XXX3 have relatively low melting points, exhibit good phase behavior, are colorless in the pure state and form liquid-crystalline mesophases in a temperature range advantageously defined for electro-optical applications. They are chemically stable, thermally stable and photostable.

[0283] The optimum quantitative ratio of the compounds of the abovementioned formulae depends essentially on the desired properties, on the choice of the components of the abovementioned formulae and on the choice of any further components that may be present.

[0284] Suitable usage ratios within the range given above can be easily determined according to circumstances.

[0285] The total amount of the compound of the formula mentioned above in the mixture according to the present invention is not critical. The mixture may therefore comprise one or more additional components to optimize various properties. However, the higher the total concentration of the compound of the formula mentioned above, the greater the effect observed on the desired improvement of the properties of the mixture.

[0286] The individual compounds of the formulae and subformulae mentioned above which can be used in the media according to the invention are known, or they can be prepared analogously to the known compounds by methods known per se, as described in the literature (for example in standard works such as Houben-Weyl, Methoden der Organischen Chemie [Organic Chemistry Methods], Georg-Thieme-Verlag, Stuttgart), more precisely under reaction conditions known and suitable for the reactions described. It is also possible to use variants known per se which are not mentioned in greater detail in this context.

[0287] Furthermore, polymerizable compounds, so-called reactive mesogens (RM), as disclosed, for example, in US Pat. No. 6,861,107, can be added to the mixtures according to the invention in a concentration of preferably 0.12 to 5% by weight, particularly preferably 0.2 to 2%, based on the mixture. These mixtures can optionally also contain polymerization initiators, as described, for example, in US Pat. No. 6,781,665. Polymerization initiators, for example (BASF), preferably added in an amount of 0 to 1% to a mixture comprising a polymerizable compound. Mixtures of this type can be used for so-called polymer stabilization ( P olymer S The (PS) mode, in which the polymerization of the reactive mesogens is intended to take place in the liquid crystal mixture, is used, for example, for PS-IPS, PS-FFS, PS-TN, PS-VA-IPS. The prerequisite for this is that the liquid crystal mixture itself does not contain polymerizable components.

[0288] In a preferred embodiment of the present invention, the polymerizable compound is selected from compounds of formula M

[0289] R a -B 1 -(Z b -B 2 ) m -R b M

[0290] where the individual radicals, independently of one another in each case and identically or differently on each occurrence, have the following meanings:

[0291] R a and R b P, P-Sp-, H, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, SF5 or straight-chain or branched alkyl having 1 to 25 C atoms, wherein, in addition, one or more non-adjacent CH2 groups may in each case 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 one another, and wherein, in addition, one or more H atoms may be replaced by F, Cl, Br, I, CN, P or P-Sp-, and wherein, if B 1 and / or B 2 Contains saturated C atoms, then R a and / or R b It may also represent a group which may be linked to such a saturated C atom via a spiro bond,

[0292] The group R a and R b at least one of means or contains a group P or P-Sp-,

[0293] P polymerizable group,

[0294] Sp spacer group or single bond,

[0295] B 1 and B 2 an aromatic, heteroaromatic, alicyclic or heterocyclic radical, preferably having 4 to 25 ring atoms, preferably C atoms, which may also contain or comprise fused rings, and which may optionally be mono- or polysubstituted by L,

[0296] LP, 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, or alkenyl or alkynyl having 2 to 25 C atoms, wherein, in addition, one or more H atoms may be replaced by F, Cl, P or P-Sp-, preferably P, P-Sp-, H, OH, CH2OH, halogen, SF5, NO2, alkyl, alkenyl or alkynyl,

[0297] Y 1 Halogen, preferably F,

[0298] Z b -O-, -S-, -CO-, -CO-O-, -OCO-, -O-CO-O-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -(CH2) n1 -, -CF2CH2-, -CH2CF2-, -(CF2) n1 -, -CH=CH-, -CF=CF-, -C≡C-, -CH=CH-, -COO-, -OCO-CH=CH-, CR 0 R 00 or single key,

[0299] R 0 and R 00 in each case independently of one another is H or alkyl having 1 to 12 C atoms,

[0300] R x 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 may 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 may 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,

[0301] m 0, 1, 2, 3 or 4,

[0302] n1 1, 2, 3, or 4.

[0303] Preferred compounds of formula M are those wherein B 1 and B 2Those which are in each case independently of one another selected from the group consisting of 1,4-phenylene, naphthalene-1,4-diyl, naphthalene-2,6-diyl, phenanthrene-2,7-diyl, anthracene-2,7-diyl, fluorene-2,7-diyl, coumarin, brass (where, in addition, one or more CH groups in these radicals may be replaced by N), cyclohexane-1,4-diyl (where, in addition, one or more non-adjacent CH2 groups may be replaced by O and / or S), 1,4-cyclohexane-1,4-diyl (where, in addition, one or more non-adjacent CH2 groups may be replaced by O and / or S), hexenyl, 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.

[0304] Particularly preferred compounds of formula M are those wherein B 1 and B 2 These are in each case independently of one another those which are 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl.

[0305] Further particularly preferred compounds of the formula M are those in which the radical R a and R b The one or two refer to those of P or P-Sp-.

[0306] Particularly preferred compounds of formula M are selected from the following formulae:

[0307]

[0308]

[0309]

[0310]

[0311]

[0312] The various groups have the following meanings:

[0313] P 1 To P 3 is in each case independently of one another a polymerizable group, preferably having one of the meanings given above and below for P, particularly preferably acrylate, methacrylate, fluoroacrylate, oxetane, vinyloxy or epoxy,

[0314] Sp 1 To Sp 3is in each case independently of one another a single bond or a spacer group, preferably has one of the meanings given above and below for Sp, particularly preferably means -(CH2) p1 -、-(CH2) p1 -O-, -(CH2) p1 -CO-O- or -(CH2) p1 -O-CO-O-, wherein p1 is an integer from 1 to 12 and wherein in the last-mentioned radicals, the connection to the adjacent ring occurs via an O atom, wherein the radical P 1 -Sp 1 -、P 2 -Sp 2 - and P 3 -Sp 3 -One of them can also refer to R aa ,

[0315] 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 in each case be replaced independently of one another 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 one another, and wherein, in addition, one or more H atoms may be replaced by F, Cl, CN or P 1 -Sp 1 - alternatively, particularly preferably linear or branched, optionally monofluorinated or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl or alkylcarbonyloxy having 1 to 12 C atoms, where alkenyl and alkynyl have at least 2 C atoms and branched radicals have at least 3 C atoms,

[0316] R 0 and R 00 in each case independently of one another and identically or differently on each occurrence means H or alkyl having 1 to 12 C atoms,

[0317] R y and R z is, in each case independently of one another, H, F, CH3 or CF3,

[0318] Z 1 Refers to -O-, -CO-, -C(R y R z )- or -CF2CF2-,

[0319] Z 2 and Z3 is, in each case independently of one another, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -(CH2) n -, where n is 2, 3, or 4,

[0320] L is identical or different on each occurrence and has the meaning given above under formula M and preferably denotes F, Cl, CN or linear or branched, optionally monofluorinated or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl or alkylcarbonyloxy having 1 to 12 C atoms, preferably F,

[0321] L' and L" are each independently H, F or Cl,

[0322] X 1 To X 3 is, in each case independently of one another, -CO-O-, -O-CO- or a single bond,

[0323] r is 0, 1, 2, 3, or 4,

[0324] s is 0, 1, 2, or 3,

[0325] t is 0, 1, or 2, and

[0326] x is either 0 or 1.

[0327] Preferred are polymerizable compounds of the formulae M2, M13, M17, M22, M23, M24 and M30. Particularly preferred are compounds of the formulae M2 and M13.

[0328] Preference is also given to trireactive compounds of the formulae M15 to M31, in particular M17, M18, M19, M22, M23, M24, M25, M30 and M31.

[0329] Further suitable and preferred polymerizable compounds are listed in Table E, for example.

[0330] In the compounds of formulae M1 to M31, the group

[0331] Preferred means

[0332]

[0333] in which L has, identically or differently on each occurrence, one of the meanings given above and below and preferably denotes 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-, particularly preferably F, Cl, CN, CH3, C2H5, OCH3, COCH3, OCF3 or P-Sp-, very particularly preferably F, Cl, CH3, OCH3, COCH3 or OCF3, in particular F or CH3.

[0334] Preferred compounds of formula M1 to M31 are those wherein P 1 , P 2 and P 3 These are acrylate, methacrylate, oxetane or epoxy groups, with particular preference given to those of acrylate or methacrylate groups.

[0335] Further preferred compounds of formula M1 to M31 are those wherein Sp 1 、Sp 2 and Sp 3 refers to those with single bonds.

[0336] Further preferred compounds of the formulae M1 to M31 are those in which the group Sp 1 、Sp 2 and Sp 3 At least one of the groups Sp 1 、Sp 2 and Sp 3 At least one of the bonds is different from those of the single bonds.

[0337] Further preferred compounds of the formulae M1 to M31 are those in which the radical Sp which is different from a single bond is 1 、Sp 2 and Sp 3 refers to -(CH2) s1 -X"-, wherein s1 refers to an integer from 1 to 6, preferably 2, 3, 4 or 5 and X" represents a connection to an adjacent benzene ring and refers to -O-, -O-CO-, -CO-O-, -O-CO-O- or a single bond.

[0338] The liquid-crystalline medium preferably comprises one, two or three polymerizable compounds of the formula M, preferably selected from the formulae M1 to M31, particularly preferably from Table E.

[0339] The liquid-crystalline media according to the present application preferably comprise in total 0.01 to 3%, preferably 0.1 to 1.0%, particularly preferably 0.1 to 0.5%, of polymerizable compounds.

[0340] It has been observed that the addition of one or more polymerizable compounds, such as selected, for example, from formula M or table E, to the liquid-crystalline media according to the invention brings about advantageous properties, such as, for example, faster response times. The liquid-crystalline media according to the invention comprising one or more polymerizable compounds of this type are particularly suitable for use in PSA displays, where they bring about advantageous properties, such as reduced image sticking, faster and more complete polymerization, faster tilt angle generation, improved tilt stability after UV irradiation, high reliability, high VHR values ​​after UV irradiation and high birefringence. Furthermore, by appropriate selection of the polymerizable compounds, the UV absorption can be shifted to longer wavelengths, so that polymerization at longer UV wavelengths can be achieved, which is advantageous for the production method of the display according to the invention.

[0341] The polymerizable group P is a group suitable for polymerization, for example free radical or ionic chain polymerization, polyaddition or polycondensation or for polymer-analogous conversion reactions, for example addition or condensation to the polymer backbone. Particularly preferred are groups for chain polymerization, in particular those containing a C=C double bond or a -C≡C- triple bond, and groups suitable for ring-opening polymerization, for example oxetane or epoxy groups.

[0342] 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 is 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 in each case independently of one another is H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 in each case independently of one another, Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W 7 and W 8 In each case, independently of one another, it is H, Cl or an alkyl radical having 1 to 5 C atoms, Phe is 1,4-phenylene which may optionally be substituted by one or more radicals L as defined above which are different from P-Sp-, k1, k2 and k3 are in each case independently of one another 0 or 1, k3 preferably being 1, and k4 being an integer from 1 to 10.

[0343] A particularly preferred group P is CH2=CW 1 -COO-, in particular CH2=CH-COO-, CH2=C(CH3)-COO- and CH2=CF-COO-, in addition CH2=CH-O-, (CH2=CH)2CH-OCO-, (CH2=CH)2CH-O-,

[0344] Very particularly preferred radicals P are vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy, in particular acrylate and methacrylate.

[0345] If Sp is different from a single bond, it is preferably selected from the formula Sp'-X', so that the group P-Sp- corresponds to the formula P-Sp'-X'-, in which

[0346] Sp' is 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 in each case independently of one another be replaced by -O-, -S-, -NH-, -NR 0 -、-SiR 00 R 000 -, -CO-, -COO-, -OCO-, -OCO-O-, -S-CO-, -CO-S-, -NR00 -CO-O-, -O-CO-NR 00 -、-NR 00 -CO-NR 00 -, -CH=CH- or -C≡C- are replaced in such a way that O and / or S atoms are not directly connected to each other,

[0347] X' refers to -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 00 -、-NR 00 -CO-、-NR 00 -CO-NR 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-COO-, -OCO-CH=CH- or a single bond,

[0348] R 00 and R 000 in each case independently of one another means H or alkyl having 1 to 12 C atoms, and

[0349] Y 2 and Y 3 In each case, independently of one another, it refers to H, F, Cl or CN.

[0350] X' is preferably -O-, -S-CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -、-NR 0 -CO-、-NR 0 -CO-NR 0 - or single key.

[0351] A typical spacer group Sp' is, for example, -(CH2) p1 -、-(CH2CH2O) q1 -CH2CH2-, -CH2CH2-S-CH2CH2-, -CH2CH2-NH-CH2CH2- or -(SiR 00 R 000 -O) p1 -, wherein p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R 00 and R 000 has the meaning given above.

[0352] 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 given above.

[0353] Particularly preferred radicals Sp′ are, for example, in each case straight-chain ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethylene-N-methyl-iminoethylene, 1-methylalkylene, vinylene, propenylene and butenylene.

[0354] In a further preferred embodiment of the present invention, P-Sp- refers to a group having two or more polymerizable groups (multifunctional polymerizable groups). Suitable groups of this type and polymerizable compounds containing them and their preparation are described, for example, in US 7,060,200 B1 or US 2006 / 0172090 A1. Particularly preferred are multifunctional polymerizable groups P-Sp- selected from the following formula

[0355] -X-Alkyl-CHP 1 -CH2-CH2P 2 I*a

[0356] -X-alkyl-C(CH2P 1 )(CH2P 2 )-CH2P 3 I*b

[0357] -X-Alkyl-CHP 1 CHP 2 -CH2P 3 I*c

[0358] -X-alkyl-C(CH2P 1 )(CH2P 2 )-C aa H 2aa+1 I*d

[0359] -X-Alkyl-CHP 1 -CH2P 2 I*e

[0360] -X-Alkyl-CHP 1 P2 I*f

[0361] -X-Alkyl-CP 1 P 2 -C aa H 2aa+1 I*g

[0362] -X-alkyl-C(CH2P 1 )(CH2P 2 )-CH2OCH2-C(CH2P 3 )(CH2P 4 )CH2P 5 I*h

[0363] -X-alkyl-CH((CH2) aa P 1 )((CH2) bb P 2 ) I*i

[0364] -X-Alkyl-CHP 1 CHP 2 -C aa H 2aa+1 I*k

[0365] -X'-alkyl-C(CH3)(CH2P 1 )(CH2P 2 ) I*m

[0366] in

[0367] Alkyl is a single bond or a straight-chain or branched alkylene radical having 1 to 12 C atoms, wherein one or more non-adjacent CH2 groups may in each case be replaced independently of one another by -C(R 00 )=C(R 000 )-、-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 one another, and wherein, in addition, one or more H atoms may be replaced by F, Cl or CN, wherein R 00 and R 000 has the meanings given above,

[0368] aa and bb, independently of one another, mean in each case 0, 1, 2, 3, 4, 5 or 6, X has one of the meanings given for X', and

[0369] P 1-5 In each case, independently of one another, it has one of the meanings given for P.

[0370] The polymerizable compounds and RMs can be prepared analogously to the methods known to the person skilled in the art and described in standard works of organic chemistry, for example Houben-Weyl, Methoden der organischen Chemie [Methods in Organic Chemistry], Thieme-Verlag, Stuttgart. Further synthesis methods can be found in the literature cited above and below. In the simplest case, the synthesis of such RMs is carried out, for example, by esterification or etherification of 2,6-dihydroxynaphthalene or 4,4'-dihydroxybiphenyl using the corresponding acids, acid derivatives or halogenated compounds containing the group P, for example (meth)acryloyl chloride or (meth)acrylic acid, in the presence of a dehydrating agent, for example DCC (dicyclohexylcarbodiimide).

[0371] For the production of the PSA displays according to the invention, the polymerizable compounds present in the LC media according to the invention are polymerized or crosslinked, preferably in situ in the display, optionally with application of a voltage to the electrodes of the display.

[0372] The structure of the LC display according to the invention corresponds to the usual geometry of PSA displays as described in the prior art cited in the introduction. Geometries without protrusions are preferred, in particular those in which the electrode on the color filter side is otherwise unstructured and only the electrode on the TFT side has slots. A particularly suitable and preferred electrode structure for PS-VA displays is described, for example, in US 2006 / 0066793 A1.

[0373] The liquid-crystal mixtures and liquid-crystal media according to the invention are suitable in principle for use in any type of PS or PSA display, in particular those based on liquid-crystal media with negative dielectric anisotropy, particularly preferably in PSA-VA, PSA-IPS or PS-FFS displays. However, the person skilled in the art can also use suitable liquid-crystal mixtures and liquid-crystal media according to the invention without inventive aid in other displays of the PS or PSA type, for example in PS-TN or PS-OCB displays, which differ from the above-mentioned displays, for example by their basic construction or by the type, arrangement or structure of the individual components used, for example substrates, alignment layers, electrodes, drive elements, backlights, polarizers, color filters, any compensation films that may be present, etc.

[0374] In a further preferred embodiment, the liquid crystal media according to the invention contain one or more chiral dopants, preferably in a concentration of 0.01 to 1% by weight, particularly preferably 0.05 to 0.5% by weight. The chiral dopant is preferably selected from the compounds in Table B below, particularly preferably from R- or S-1011, R- or S-2011, R- or S-3011, R- or S-4011, and R- or S-5011.

[0375] In a further preferred embodiment, the liquid-crystalline media according to the invention comprise the racemates of one or more chiral dopants, preferably selected from the preferred chiral dopants mentioned above.

[0376] In a further preferred embodiment, the liquid-crystalline media according to the invention contain a "self-aligning" (SA) additive, preferably in a concentration of 0.1 to 2.5% by weight. Media of this type are particularly suitable for SA-FFS or SA-HB-FFS displays, which may also be polymer-stabilized.

[0377] In a preferred embodiment, the SA-FFS or SA-HB-FFS display contains no alignment layer, in particular a polyimide alignment layer.

[0378] Preferred SA additives are selected from compounds containing a mesogenic group and a linear or branched alkyl side chain containing a terminal polar anchoring group, which is preferably selected from hydroxyl, carboxyl, amino and thiol groups.

[0379] In addition to the polar anchoring group, further preferred SA additives also contain one or more polymerizable groups, which are optionally connected to the mesogenic group via a spacer group. These polymerizable SA additives can be polymerized in the liquid crystal medium under the same or similar conditions as the polymerizable compounds or RMs mentioned above.

[0380] Suitable and preferred SA additives are disclosed, for example, in US 2013 / 0182202 A1, US 2014 / 0838581 A1, US 2015 / 0166890 A1 and US 2015 / 0252265 A1.

[0381] Further suitable and preferred SA additives are selected from Table F below.

[0382] The invention also provides for the use of the mixtures according to the invention in electro-optical displays and for the use of the mixtures according to the invention in LC windows, in shutter glasses, in particular for 3D applications, and in TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS, positive VA and PS-positive-VA displays.

[0383] The invention also provides electro-optical displays, LC windows, shutter glasses for 3D applications and LC displays of the TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS, positive-VA or positive-PS-VA type which contain the liquid-crystalline media according to the invention.

[0384] The invention also provides electro-optical displays containing media of this type, such as STN or MLC displays, which have two plane-parallel carrier plates which together with a frame form a liquid crystal cell, an integrated non-linear element for switching the individual pixels on the carrier plates and a nematic liquid crystal mixture with positive dielectric anisotropy and high specific resistance located in the liquid crystal cell, and also relates to the use of these media for electro-optical purposes.

[0385] The liquid-crystal mixtures according to the invention make it possible to significantly broaden the usable parameter range. The achievable combination of clearing point, viscosity at low temperatures, thermal and UV stability and high optical anisotropy is far superior to the materials from the prior art to date.

[0386] The mixtures according to the invention are particularly suitable for mobile applications and TFT applications, such as mobile phones and PDAs. The mixtures according to the invention can also be used in FFS, IPS, OCB and IPS displays.

[0387] The liquid crystal mixture according to the present invention can achieve a rotational viscosity γ1 of ≤110 mPa·s, particularly preferably ≤100 mPa·s, while maintaining a nematic phase as low as -20°C, preferably as low as -30°C, particularly preferably as low as -40°C and a clearing point of ≥70°C, preferably ≥72°C, thereby enabling an excellent MLC display with a fast response time. The rotational viscosity is measured at 20°C.

[0388] The dielectric anisotropy Δε of the liquid crystal mixture according to the invention at 20°C is preferably ≥+7, particularly preferably ≥+8, and particularly preferably ≥10. In addition, the mixture is characterized by a low operating voltage. The threshold voltage of the liquid crystal mixture according to the invention is preferably ≤2.0 V. The birefringence Δn of the liquid crystal mixture according to the invention at 20°C is preferably ≥0.09, particularly preferably ≥0.10.

[0389] The nematic phase range of the liquid-crystal mixture according to the invention preferably has a width of at least 90°, in particular at least 100°. This range preferably extends at least from -25°C to +70°C.

[0390] It goes without saying that by suitable selection of the components of the mixture according to the invention, it is also possible to achieve higher clearing points (for example above 100° C.) at higher threshold voltages or lower clearing points at lower threshold voltages while maintaining other advantageous properties. At a correspondingly only slightly increased viscosity, it is likewise possible to obtain mixtures with a greater Δε and thus a low threshold. The MLC display according to the invention is preferably operated at the first Gooch and Tarry transmission minimum [CH Gooch and HATarry, Electron. Lett. 10, 2-4, 1974; CH Gooch and HATarry, Appl. Phys., Vol. 8, 1575-1584, 1975], wherein, in addition to particularly advantageous electro-optical properties, such as high steepness of characteristic lines and low angular dependence of contrast (German Patent 30 22 818), a lower dielectric anisotropy at the same threshold voltage as in similar displays is sufficient at the second minimum. Thus, using the mixture according to the invention enables significantly higher specific resistances to be achieved at the first minimum than in the case of mixtures comprising cyano compounds. By suitable selection of the individual components and their weight proportions, a person skilled in the art is able to adjust the birefringence necessary for a predetermined layer thickness for an MLC display using simple conventional methods.

[0391] Measurement of voltage holding ratio (HR) [S. Matsumoto et al., Liquid Crystals 5 , 1320 (1989); K. Niwa et al., Proc. SID Conference, San Francisco, June 1984, p. 304 (1984); G. Weber et al., Liquid Crystals 5 ,1381(1989)] have shown that Cyanophenylcyclohexane or The mixture according to the invention comprising one or more compounds of formula 1 and one or more compounds of formula 2 and one or more compounds of formulae 3 to 5 and one or more compounds of formulae 6 and / or 7 has a significantly smaller reduction in HR under UV irradiation compared to a similar mixture of esters of formulae.

[0392] The light and UV stability of the mixtures according to the invention are significantly better, ie they exhibit a significantly smaller decrease in HR under irradiation with light or UV.

[0393] The construction of the MLC display according to the invention consisting of polarizer, electrode substrate and electrodes with surface treatment corresponds to the conventional design of displays of this type. The term "conventional design" is to be understood in a broad sense and also encompasses all derivatives and variants of MLC displays, in particular also matrix display elements based on poly-Si TFTs or MIMs.

[0394] However, the display according to the invention differs substantially from hitherto conventional displays based on twisted nematic liquid crystal cells in the choice of the liquid crystal parameters in the liquid crystal layer.

[0395] The liquid crystal mixture that can be used according to the present invention is prepared in a conventional manner per se, for example by mixing one or more compounds of formula 1 and one or more compounds of formula 2 with one or more compounds of formula 3 to 5 and one or more compounds of formula 6 and / or 7 and optionally one or more compounds of formula II-XXIII or with other liquid crystal compounds and / or additives. In general, the required amount of the component used in a smaller amount is dissolved in the component constituting the main component, if necessary, at an elevated temperature. It is also possible to mix the components in an organic solvent, for example a solution in acetone, chloroform or methanol, and remove the solvent again after sufficient mixing, for example by distillation.

[0396] The dielectric may also contain other additives known to the person skilled in the art and described in the literature, for example, UV stabilizers such as TUNA® from Ciba Chemicals. For example 770, antioxidants, such as TEMPOL, microparticles, free radical scavengers, nanoparticles, etc. For example, 0 to 15% of pleochroic dyes or chiral dopants may be added. Suitable stabilizers and dopants are indicated in Tables C and D below.

[0397] In the present application and in the following examples, the structures of the liquid-crystal compounds are indicated by means of acronyms, with conversion into chemical formulae according to Table A. n H 2n+1 and C m H 2m+1 is a straight-chain alkyl radical having n and m C atoms, respectively; n, m and k are integers and preferably refer to 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, particularly preferably 1, 2, 3, 4, 5, 6 or 7. The coding according to Table B is self-explanatory. In Table A, only the acronym of the parent structure is shown. In individual cases, the substituent R is connected after the acronym of the parent structure separated by a dotted line. 1* , R 2* , L 1* and L 2* The code:

[0398]

[0399] Preferred mixture compositions are shown in Tables A and B.

[0400] Table A

[0401]

[0402]

[0403]

[0404] Table B

[0405] In the following formulae, n and m are in each case independently of one another 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, in particular 2, 3, 5, furthermore 0, 4, 6 and preferably not 0.

[0406]

[0407]

[0408]

[0409]

[0410]

[0411]

[0412]

[0413]

[0414]

[0415] Particular preference is given to liquid-crystal mixtures which, in addition to the compounds of the formulae 1 and 2 and (3 to 5) and 6 and / or 7, comprise at least one, two, three, four or more compounds from Table B.

[0416] Table C

[0417] Table C shows possible dopants which are usually added to the mixture according to the invention. The mixture preferably comprises 0 to 10% by weight, in particular 0.01 to 5% by weight, particularly preferably 0.01 to 3% by weight of dopant.

[0418]

[0419]

[0420] Table D

[0421] Indicated below are stabilizers which can be added to the mixture according to the invention, for example in amounts of 0 to 10% by weight.

[0422]

[0423]

[0424]

[0425]

[0426]

[0427]

[0428] Table E

[0429] Table E brings together exemplary compounds which can preferably be used as reactive mesogenic compounds in the liquid-crystalline media according to the invention. If the mixture according to the invention comprises one or more reactive compounds, they are preferably used in an amount of 0.01 to 5% by weight. If necessary, for the polymerization, it may also be necessary to add an initiator or a mixture of two or more initiators. The initiator or initiator mixture is preferably added in an amount of 0.001 to 2% by weight, based on the mixture. Suitable initiators are, for example, (BASF Corporation).

[0430]

[0431]

[0432]

[0433]

[0434]

[0435]

[0436]

[0437]

[0438]

[0439]

[0440]

[0441]

[0442]

[0443]

[0444]

[0445]

[0446]

[0447]

[0448]

[0449] In a preferred embodiment, the liquid-crystalline media according to the invention comprise one or more polymerizable compounds selected from Table E, preferably selected from the polymerizable compounds of formulae RM-1 to RM-144, particularly preferably selected from the formulae RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM-40, RM-41, RM-48, RM-52, RM-54, RM-57, RM-64, RM-74, RM-76, RM-88, RM-102, RM-103, RM-109, RM-117, RM-120, RM-121 and RM-122.

[0450] Table F

[0451] Table F shows the SA additives that can be preferably used in the media according to the invention:

[0452]

[0453]

[0454]

[0455]

[0456]

[0457]

[0458]

[0459]

[0460]

[0461]

[0462] In a preferred embodiment, the liquid-crystalline media according to the invention comprise one or more SA additives selected from the formulae SA-1 to SA-44, particularly preferably from the formulae SA-14 to SA-34 and SA-44, very particularly preferably from the formulae SA-20 to SA-34 and SA-44.

[0463] The following mixture examples are intended to illustrate the invention without limiting it.

[0464] In this context, percentage data refer to percentages by weight. All temperatures are given in ° C. mp = melting point, cl.p. = clearing point. In addition, C = crystalline, N = nematic, S = smectic, I = isotropic. The data between these symbols represent transition temperatures. In addition,

[0465] -Δn refers to the optical anisotropy at 589 nm and 20°C,

[0466] -γ1 refers to the rotational viscosity at 20°C (mPa·s),

[0467] - Δε refers to the dielectric anisotropy at 20°C and 1kHz (Δε = ε || -ε ⊥ , where ε || refers to the dielectric constant parallel to the long axis of the molecule, ε ⊥ refers to the dielectric constant perpendicular to it).

[0468] -V 10 It refers to the voltage (V) (threshold voltage) at 10% transmission (viewing angle perpendicular to the panel surface), measured at 20°C in a TN liquid crystal cell (90° twist) at the first minimum (i.e. at a d·Δn value of 0.5 μm),

[0469] -V0 refers to the Freedericks threshold voltage measured by capacitance method at 20°C in an antiparallel rubbed liquid crystal cell,

[0470] Unless expressly stated otherwise, LTS refers to the storage or low temperature stability measured in hours (h) at a temperature of -20°C in a test cell suitable for this purpose.

[0471] Unless explicitly stated otherwise, all physical properties are measured according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status, November 1997, Merck KGaA, Germany, and apply to a temperature of 20°C.

[0472] Comparative Example 1

[0473]

[0474] Example 1

[0475]

[0476]

[0477] Example 2

[0478]

[0479] Example 3

[0480]

[0481]

[0482] Example 4

[0483]

[0484] Comparative Example 2

[0485]

[0486] Example 5

[0487]

[0488] Example 6

[0489]

[0490] Example 7

[0491]

[0492] Example 8

[0493]

[0494] Example 9

[0495]

[0496] Example 10

[0497]

[0498] Comparative Example 3

[0499]

[0500]

[0501] Embodiment 11

[0502]

[0503] Example 12

[0504]

[0505]

[0506] Example 13

[0507] 0.04% of the following compound was added as stabilizer to the mixture from Example 1:

[0508]

[0509] Embodiment 14

[0510] 0.05% of the following compound was added as a stabilizer to the mixture from Example 5:

[0511]

[0512] Embodiment 15

[0513] 0.03% of the following compound was added as a stabilizer to the mixture from Example 11:

[0514]

[0515] Example 16

[0516] 0.04% of the following compound was added as stabilizer to the mixture from Example 2:

[0517]

[0518] Embodiment 17

[0519] 0.03% of the following compound was added as stabilizer to the mixture from Example 7:

[0520]

[0521] VHR measurement

[0522] To determine the voltage holding ratio (VHR) or its stability after BL stress (BL = backlight), the respective mixture was filled into a test cell with an alignment material for parallel alignment in a TN configuration and a flat ITO electrode. The VHR of the respective mixture was then measured (measuring instrument: Autronic VHRM 105, signal amplitude: 1 V, pulse width 60 μs, measuring frequency 60 Hz, temperature 100° C.).

[0523] The corresponding test cells were subsequently exposed to a cold cathode (CCFL) LCD backlight for a duration of up to 1000 hours. After certain time intervals, the VHR was measured in each case as described above.

[0524] For each individual mixture, a measurement series consisting of in each case 4 test cells was filled and investigated. The indicated values ​​are the average of the individual values ​​measured. The results are summarized in Table 1.

[0525] Table 1 - VHR values

[0526]

[0527] 1) After 500h

[0528] As can be seen from Table 1, the mixture according to the invention has a significantly smaller drop in VHR after BL stressing and thus a significantly higher VHR stability than the comparative mixture.

[0529] It can further be seen from the examples shown above that the mixtures according to the invention have LTS values ​​at least as good or higher than the comparative mixtures, in particular at low temperatures (-30° C.).

Claims

1. A liquid crystal medium, characterized in that It has positive dielectric anisotropy and comprises one or more compounds selected from the group consisting of compounds of formula IA1a and IA1b and one or more compounds of formula IB1a The liquid crystal medium does not contain a group R selected from 1 and R 2 has the following meanings and in addition one or two radicals R 1 or R 2 Compounds of formula IA and IB containing a C=C double bond Where R 1 and R 2 in each case independently of one another, alkyl, alkoxy, oxaalkyl or fluoroalkyl, in each case having 1 to 7 C atoms; The liquid-crystalline medium further comprises one or more compounds selected from the group consisting of the formulae XVIb1, XVIb2 and XVIb3 2. Liquid-crystalline medium according to claim 1, characterized in that It further comprises one or more compounds of formula IA selected from the following sub-formulae where the individual radicals, in each case independently of one another and identically or differently on each occurrence, have the following meanings Alkyl, alkyl*: straight-chain alkyl radicals with 1-6 C atoms, alkoxy: straight-chain alkoxy with 1-6 C atoms, Compounds of formula IA1 here exclude compounds of formula IA1a and IA1b.

3. Liquid-crystalline medium according to claim 1 or 2, characterized in that It further comprises one or more compounds of formula IB selected from the following sub-formulae in Alkyl: a straight chain alkyl group having 1-6 C atoms, Alkoxy: straight chain alkoxy with 1-6 C atoms Here, the compound of formula IB1 excludes the compound of formula IB1a.

4. Liquid-crystalline medium according to claim 1, characterized in that It further comprises one or more compounds selected from the following sub-formulae 5. Liquid-crystalline medium according to claim 1 or 2, characterized in that It further comprises one or more compounds selected from the following formula where the individual radicals, in each case independently of one another and identically or differently on each occurrence, have the following meanings R 0 unsubstituted or halogenated alkyl or alkoxy radicals having 1 to 15 C atoms, wherein, in addition, one or more CH2 radicals in these radicals may in each case independently of one another be replaced by -CF2O-, -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly attached to each other, X 0 F, Cl, haloalkyl, haloalkoxy or haloalkenyloxy, in each case with up to 6 C atoms, Y 1 、Y 2 、Y 5 、Y 6 H or F, Y 0 H or CH3.

6. Liquid-crystalline medium according to claim 1 or 2, characterized in that It further comprises one or more compounds selected from the following formula in R 0 unsubstituted or halogenated alkyl or alkoxy radicals having 1 to 15 C atoms, wherein, in addition, one or more CH2 radicals in these radicals may in each case independently of one another be replaced by -CF2O-, -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly attached to each other, X 0 F, Cl, haloalkyl, haloalkoxy or haloalkenyloxy, in each case with up to 6 C atoms, Y 1 , Y 2 , Y 3 , Y 4 denotes H or F in each case independently of one another, Z 0 It means -C2H4-, -(CH2)4-, -CH=CH-, -CF=CF-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH2O-, -OCH2-, -COO- or -OCF2- also refers to a single bond in formulas V and VI, and also refers to -CF2O- in formulas V and VIII, r is 0 or 1, and s refers to 0 or 1.

7. Liquid-crystalline medium according to claim 1 or 2, characterized in that It further comprises one or more compounds of the formula in R 0 unsubstituted or halogenated alkyl or alkoxy radicals having 1 to 15 C atoms, wherein, in addition, one or more CH2 radicals in these radicals may in each case independently of one another be replaced by -CF2O-, -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly attached to each other, X 0 F, Cl, haloalkyl, haloalkoxy or haloalkenyloxy, in each case with up to 6 C atoms, Y 1 、Y 2 H or F.

8. Liquid-crystalline medium according to claim 1 or 2, characterized in that It further comprises one or more compounds of the formula R 0 unsubstituted or halogenated alkyl or alkoxy radicals having 1 to 15 C atoms, wherein, in addition, one or more CH2 radicals in these radicals may in each case independently of one another be replaced by -CF2O-, -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly attached to each other, X 0 F, Cl, haloalkyl, haloalkoxy or haloalkenyloxy, in each case with up to 6 C atoms, Y 1 、Y 2 H or F.

9. Liquid-crystalline medium according to claim 1 or 2, characterized in that It further comprises one or more compounds of the formula in R 0 unsubstituted or halogenated alkyl or alkoxy radicals having 1 to 15 C atoms, wherein, in addition, one or more CH2 radicals in these radicals may in each case independently of one another be replaced by -CF2O-, -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly attached to each other, Y 2 , Y 3 , Y 4 In each case, independently of one another, it represents H or F.

10. Liquid-crystalline medium according to claim 1 or 2, characterized in that It further comprises one or more compounds selected from the following formula Where R 1 and R 2 have in each case independently of one another the meaning given in claim 1 and L means H or F.

11. Liquid-crystalline medium according to claim 1 or 2, characterized in that The liquid-crystalline medium comprises three compounds selected from the group consisting of formulae XVIb1, XVIb2 and XVIb3.

12. Liquid-crystalline medium according to claim 1 or 2, characterized in that It further comprises one or more compounds selected from the following formula in R 1 and R 2 have in each case independently of one another the meaning given in claim 1 and L means H or F.

13. Liquid-crystalline medium according to claim 1 or 2, characterized in that It further comprises one or more compounds selected from the following formula in R 0 unsubstituted or halogenated alkyl or alkoxy radicals having 1 to 15 C atoms, wherein, in addition, one or more CH2 radicals in these radicals may in each case independently of one another be replaced by -CF2O-, -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly attached to each other, X 0 F, Cl, haloalkyl, haloalkoxy or haloalkenyloxy, in each case with up to 6 C atoms, Y 1 、Y 2 、Y 3 、Y 4 H or F.

14. Liquid-crystalline medium according to claim 1 or 2, characterized in that It further comprises one or more stabilizers selected from the following formula where the individual radicals, in each case independently of one another and identically or differently on each occurrence, have the following meanings R a-d a straight-chain or branched alkyl radical having 1 to 10 C atoms, X S H, CH3, OH or O ● , A S linear, branched or cyclic alkylene having 1 to 20 C atoms, which is optionally substituted, n is an integer from 1 to 6.

15. Liquid-crystalline medium according to claim 1 or 2, characterized in that It does not comprise compounds containing a C═C double bond, except for a C═C double bond which is a component of a polymerizable group or an aromatic or unsaturated ring.

16. Process for preparing a liquid-crystalline medium according to any one of claims 1 to 15, characterized in that All compounds comprised by the liquid-crystalline medium are mixed.

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

18. The method according to claim 17, wherein the liquid-crystalline medium is used in TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS, positive-VA or PS-positive-VA displays, liquid-crystalline windows or shutter glasses for 3D applications.

19. Liquid-crystal display comprising a liquid-crystal medium according to any one of claims 1 to 15.

20. The liquid crystal display according to claim 19, characterized in that It is a TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS, Positive-VA or PS-Positive-VA display.

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