Liquid crystal medium

Abstract

The present invention relates to a liquid crystal medium which comprises a compound of formula I and a neutral compound of formula N, wherein R 1 and X 1 and R N1 , R N2 , A N1 , A N2 , A N3 , Z N1 and Z N2 have the meanings specified in claim 1, and also relates to the use of said liquid crystal matrix in electro-optical liquid crystal displays, in particular in TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS or PS-FFS-, positive VA displays and in shutter glasses and LC lenses for 3D effects.

Description

[0001] This application is a divisional application of the application with the filing date of August 5, 2016, Chinese application number 201610841375.X, and invention title "Liquid Crystal Medium". Technical Field

[0002] The present invention relates to a liquid crystal medium (LC medium), its use for electro-optical purposes, and an LC display containing such a medium. Background Art

[0003] Liquid crystals are in principle used as dielectrics in display devices because the optical properties of such substances can be changed by an applied voltage. Electro-optical devices based on liquid crystals are well known to those skilled in the art and can be based on a variety of effects. Examples of such devices are cells with dynamic scattering, DAP (distorted alignment phase) cells, host / guest cells, TN (twisted nematic) cells with a "twisted nematic" structure, STN ("super twisted nematic") cells, SBE ("super birefringence effect") cells, and OMI ("optical mode interference") cells. The most common display devices are based on the Schadt-Helfrich effect and have a twisted nematic structure. Additionally, there are cells that operate with an electric field parallel to the substrate and the liquid crystal plane, for example, IPS ("in-plane switching") cells. In particular, TN, STN, FFS (fringe field switching), and IPS cells are currently commercially interesting application areas for the medium according to the present invention.

[0004] Liquid crystal materials must have good chemical and thermal stability as well as good stability towards electric fields and electromagnetic radiation. In addition, the liquid crystal materials should have low viscosity and produce short addressing times, low threshold voltages, and high contrast ratios in the cells.

[0005] Furthermore, at normal operating temperatures, i.e., in the widest possible range around room temperature, they should have a suitable mesophase, such as the nematic or cholesteric mesophase of the above-mentioned cells. Since liquid crystals are usually used as mixtures of multiple components, it is important that the individual components mix easily with each other. Depending on the type of cell and the application area, other properties such as conductivity, dielectric anisotropy, and optical anisotropy must meet various requirements. For example, materials for cells with a twisted nematic structure should have positive dielectric anisotropy and low conductivity.

[0006] For example, for matrix liquid crystal displays (MLC displays) with integrated non-linear elements for switching individual pixels, a medium with large positive dielectric anisotropy, a wide nematic phase, relatively low birefringence, very high specific resistance, good UV and temperature stability, and low vapor pressure is ideal.

[0007] This type of matrix liquid crystal display is known. Examples of non-linear elements that can be used to individually switch single pixels are active elements (i.e., transistors). Subsequently, the term "active matrix" is used, where a distinction is made between the following two types:

[0008] 1. MOS (metal oxide semiconductor) or other diodes located on a silicon wafer serving as a substrate.

[0009] 2. Thin film transistors (TFTs) located on a glass plate serving as a substrate.

[0010] Using single-crystalline silicon as a substrate material limits the display size because there are problems at the joints even with the modular assembly of multiple partial displays.

[0011] In the case of the more promising type 2 (which is preferred), the electro-optical effect used is usually the TN effect. There is a distinction between two technologies: TFTs containing compound semiconductors, e.g., CdSe, or TFTs based on polycrystalline or amorphous silicon. The latter technology is being intensively developed worldwide.

[0012] The TFT matrix is applied to the inner side of one glass plate of the display, while the other glass plate carries a transparent counter electrode on its inner side. Compared to the size of the pixel electrodes, the TFTs are very small and have no substantial adverse effect on the image. This technology can also be extended to displays capable of full color, where mosaics of red, green, and blue filters are arranged in such a way that the filter elements are relative to each switchable pixel.

[0013] TFT displays typically operate as TN panels with crossed polarizers in transmission and are backlit.

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

[0015] This type of MLC display is particularly suitable for TV applications (such as pocket TVs) or computer applications (notebooks) and high-information displays in automotive or aircraft construction. In addition to problems regarding the angular dependence of contrast and response time, MLC displays also have problems due to the not high enough specific resistance of the liquid crystal mixture [TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K., TAJIMA, E., WATANABE, H., SHIMIZU, H., Proc. Eurodisplay 84, Sept. 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, pp. 141ff., Paris; STROMER, M., Proc. Eurodisplay 84, Sept. 1984: Design of Thin Film Transistors for Matrix Addressing of Television Liquid Crystal Displays, pp. 145ff., Paris]. As the resistance decreases, the contrast of the MLC display deteriorates, and problems of after-image elimination may occur. Due to the interaction of the inner surfaces of the display, the specific resistance of the liquid crystal mixture usually decreases with the lifetime of the MLC display, and in order to obtain an acceptable lifetime, a high (initial) resistance is very important. Especially in the case of low-voltage mixtures, it has not been possible so far to achieve very high specific resistance values. In addition, it is important that the specific resistance shows the smallest possible increase with increasing temperature and after heating and / or UV exposure. The low-temperature performance of mixtures from the prior art is also particularly disadvantageous. Crystallization and / or smectic phases should not occur, even at low temperatures, and the temperature dependence of the viscosity should be as low as possible. Therefore, MLC displays from the prior art do not meet current requirements.

[0016] In addition to liquid crystal displays that use backlighting (i.e., operate transmissively and, if desired, transflectively), reflective liquid crystal displays are also of particular interest. These reflective liquid crystal displays use ambient light for information display. They thus consume significantly less energy compared to backlit liquid crystal displays of corresponding size and resolution. Due to the TN effect being characterized by very good contrast, this type of reflective display can even be read well under bright ambient conditions. This is the simple reflective TN display that has been known, such as, for example, those used in watches and pocket calculators. However, this principle can also be applied to high-quality, higher-resolution active matrix addressed displays, such as TFT displays. Here, as already in conventional transmissive TFT-TN displays, in order to achieve a low optical retardation (d·Δn), liquid crystals with a low birefringence (Δn) must be used. This low optical retardation results in a generally acceptable low viewing angle dependence of the contrast (see DE30 22 818). In reflective displays, the use of liquid crystals with low birefringence is even more important than in transmissive displays because the effective layer thickness through which the light passes in a reflective display is approximately twice that in a transmissive display with the same layer thickness.

[0017] For TV and video applications, in order to be able to reproduce multimedia content, such as movies and video games, with near-realistic quality, displays with fast response times are required. Such short response times can be achieved particularly if a liquid crystal medium with a low viscosity value (especially the rotational viscosity γ1) and a high optical anisotropy (Δn) is used.

[0018] For achieving a 3D effect with shutter glasses, fast-switching mixtures with a low rotational viscosity and a correspondingly high optical anisotropy (Δn) are particularly used. The use of mixtures with a high optical anisotropy (Δn) enables an electro-optical lens system through which the two-dimensional representation of the display can be converted into a three-dimensional autostereoscopic representation.

[0019] In the case of TN (Schadt-Helfrich) panels, it is desirable for the medium to promote the following advantages in the panel:

[0020] - An extended nematic phase range (especially down to low temperatures)

[0021] - The ability to switch at very low temperatures (outdoor use, automotive, avionics)

[0022] - Increased UV radiation resistance (longer lifetime)

[0023] - A low threshold voltage.

[0024] Media available from the prior art cannot enable these advantages while maintaining other parameters.

[0025] In the case of a super-twisted (STN) panel, it is desirable for the medium to promote greater multiplexability and / or lower threshold voltage and / or wider nematic range (especially at low temperatures). To this end, there is an urgent desire to further widen the available parameter dimensions (clear point, smectic-nematic transition or melting point, viscosity, dielectric parameters, elastic parameters).

[0026] One of the most important properties of modern LCDs is the correct reproduction of moving images. If the response speed of the liquid crystal medium used is too slow, this causes unwanted artefacts in the display of such content. The physical parameters that basically determine the response time of a liquid crystal mixture are the rotational viscosity γ1 and the elastic constant. The latter is also particularly important for ensuring a good black state of the LCD. However, generally, it is observed that the clear point of the mixture and thus the rotational viscosity of the mixture also increase with increasing elastic constant, which means that an improvement in the response time is not possible. Especially in the case of LC displays for TV and video applications (such as LCD TVs, monitors, PDAs, notebooks, game consoles), a significant reduction in the response time is desired. A reduction in the layer thickness d ("panel gap") of the LC medium in the LC panel theoretically leads to a faster response time, but an LC medium with a higher birefringence Δn is required to ensure an appropriate optical delay (d·Δn). However, LC materials with a high birefringence known in the prior art usually also have a high rotational viscosity at the same time, which in turn has a negative impact on the response time.

[0027] Therefore, there is still a great demand for liquid crystal media that have good reliability properties (such as high VHR (voltage holding ratio)) and do not exhibit these properties or only exhibit these properties to a lesser extent. Summary of the Invention

[0028] It is an object of the present invention to provide a medium having the desired properties mentioned above and not exhibiting the disadvantages mentioned above or only exhibiting the disadvantages mentioned above to a reduced extent, especially for these types of displays of MLC, TN, STN, OCB, positive VA, FFS, HB(= high brightness)-FFS, PS(= Polymer stabilization )-FFS, IPS, PS-IPS. In particular, the LC medium should simultaneously have a fast response time and a low rotational viscosity and a relatively high birefringence. In addition, the LC medium should have a high clear point and very good low-temperature stability (LTS).

[0029] It has now been found that this object can be achieved if an LC medium containing one or more compounds of formula I is used.

[0030] The present invention relates to a liquid crystal medium, characterized in that it contains one or more compounds of formula I,

[0031]

[0032] wherein

[0033] R 1 represents an alkyl or alkoxy group having 1 - 15 C atoms, where, additionally, one or more CH2 groups in these groups may each independently of one another be replaced by -C≡C-, -CF2O-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not directly linked to one another, and where, additionally, one or more H atoms may be replaced by halogen, and

[0034] X 1 represents an alkyl group having 1 - 5 C atoms, OCF3, CF3, CHF2, OCHF2, OCF2CF3, CCF2CHFCF3, OCF=CF2, OCH=CF2 or F.

[0035] The compounds of formula I result in LC mixtures having the desired properties indicated above, in particular LC mixtures having a very low rotational viscosity. The mixtures according to the invention have very large elastic constants and thus promote a very good response time. Furthermore, the mixtures according to the invention are stable at least at -20 °C and do not exhibit a tendency to crystallize. The rotational viscosity γ1 is generally < 120 mPa·s. Furthermore, the mixtures according to the invention are characterized by a very good ratio of rotational viscosity γ1 to the clearing point, a low γ1 / K 11 value, which results in a faster response time as well as a high clearing point and a wide nematic phase range. Furthermore, the compounds of formula I are readily soluble in the liquid crystal medium.

[0036] The compounds of formula I have a wide range of applications and are in particular characterized by very large elastic constants. Depending on the choice of substituents, they can be used as base materials mainly comprising a liquid crystal medium; however, in order to influence, for example, the dielectric anisotropy and / or the optical anisotropy of dielectrics of this type and / or to optimize their threshold voltage and / or their rotational viscosity, liquid crystal base materials from other classes of compounds can also be added to the compounds of formula I. The resulting LC mixtures according to the invention support a good black state of the display due to their high elastic constants, which is crucial for the contrast of the display, and at the same time promote a very good response time.

[0037] In the compounds of formula I and the sub-formulas, R 1Preferably represents a straight-chain alkyl group, especially having 3 - 5 C atoms. In a further preferred embodiment, one or more CH2 groups in the alkyl group can also be replaced by -CH=CH-.

[0038] The following shows particularly preferred compounds of formula I:

[0039]

[0040]

[0041] wherein R 1 has the meaning indicated in claim 1, preferably a straight-chain alkyl or alkenyl group having at most 5 C atoms, and "alkyl" represents a straight-chain alkyl group having 1 - 5 C atoms.

[0042] Compounds of formula I-1, formula I-2 and formula I-5 are very particularly preferred.

[0043] The following shows very particularly preferred compounds:

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050] In the compounds of formula I-5a to formula I-5k, alkyl particularly preferably represents CH3 or C2H5, especially CH3.

[0051] In the pure state, the compounds of formula I are colorless and form a liquid-crystalline mesophase in a temperature range advantageously suitable for electro-optical applications. They are chemically stable, thermally stable and light-stable.

[0052] The compounds of formula I are prepared by methods known per se as described in the literature (for example in standard works such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), precisely under reaction conditions known and suitable for the said reaction. Variants which are not mentioned in more detail here but are known per se can also be used here. The compounds of formula I can be prepared, for example, as follows:

[0053] Scheme 1

[0054]

[0055] Scheme 2

[0056]

[0057] If in the context of formula I, R 1 denotes an alkyl and / or an alkoxy group, which may be straight-chain or branched. It is preferably straight-chain and has 2, 3, 4, 5, 6 or 7 C atoms and accordingly preferably denotes ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy. In addition, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy or tetradecyloxy.

[0058] Oxaalkyl preferably denotes straight-chain 2-oxapropyl (=methoxymethyl), 2-(=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3- or 4-oxaheptyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl.

[0059] If R 1An alkyl group in which one of the CH2 groups has been replaced by -CH=CH-, which may be straight-chain or branched. It is preferably straight-chain and has 2-10 C atoms. Accordingly, it particularly represents vinyl, prop-1-enyl, prop-2-enyl, but-1-enyl, but-2-enyl, but-3-enyl, pent-1-enyl, pent-2-enyl, pent-3-enyl, pent-4-enyl, hex-1-enyl, hex-2-enyl, hex-3-enyl, hex-4-enyl, hex-5-enyl, hept-1-enyl, hept-2-enyl, hept-3-enyl, hept-4-enyl, hept-5-enyl, hept-6-enyl, oct-1-enyl, oct-2-enyl, oct-3-enyl, oct-4-enyl, oct-5-enyl, oct-6-enyl, oct-7-enyl, non-1-enyl, non-2-enyl, non-3-enyl, non-4-enyl, non-5-enyl, non-6-enyl, non-7-enyl, non-8-enyl, dec-1-enyl, dec-2-enyl, dec-3-enyl, dec-4-enyl, dec-5-enyl, dec-6-enyl, dec-7-enyl, non-8-enyl or non-9-enyl. These groups may also be mono-halogenated or poly-halogenated.

[0060] If R 1 Represents an alkyl or alkenyl group that is at least monosubstituted by a halogen, the 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 at any desired position, but is preferably at the ω-position.

[0061] X 1 Preferably represents an alkyl group, especially CH3 and CF3, and OCF3.

[0062] The present invention also relates to compounds of formula I and its sub-formulas.

[0063] The following gives preferred embodiments of the liquid crystal mixture according to the present invention:

[0064] - The medium additionally contains one or more neutral compounds of formula II and / or formula III,

[0065]

[0066]

[0067] Wherein

[0068] A represents 1,4-phenylene or trans-1,4-cyclohexylene,

[0069] a is 0 or 1,

[0070] R 3 Represents an alkenyl group having 2-9 C atoms,

[0071] and R 4 has the meaning indicated for R in formula I and preferably represents an alkyl group having 1 - 12 C atoms or an alkenyl group having 2 - 9 C atoms. 1

[0072] - The compounds of formula II are preferably selected from the compounds of the following formula:

[0073]

[0074] wherein R 3a and R 4a each independently of one another represent H, CH3, C2H5 or C3H7, and "alkyl" represents a straight-chain alkyl group having 1 - 8 C atoms. Compounds of formula IIa and formula IIf are particularly preferred, especially those wherein R 3a represents H or CH3, and compounds of formula IIc, especially those wherein R 3a and R 4a represent H, CH3 or C2H5.

[0075] Furthermore, compounds of formula II having a non-terminal double bond in the alkenyl side chain are preferred

[0076]

[0077] Very particularly preferred compounds of formula IIa are the compounds of the following formula

[0078]

[0079]

[0080] Among the compounds of formula IIa-1 to formula IIa-19, particularly preferred are the compounds of formula IIa-1, formula IIa-2, formula IIa-3, formula IIa-5 and formula IIc-1.

[0081] In addition to one or more compounds of formula I, the liquid crystal medium according to the invention particularly preferably additionally comprises a compound of the following formula (CC-3-V),

[0082]

[0083] in a concentration of preferably 5 - 70% by weight, especially 10 - 65% by weight and very particularly preferably 20 - 55% by weight, based on the mixture.

[0084] Preferred compounds of formula IIb are the compounds of the following formula

[0085]

[0086] ​Preferred compounds of formula IIc are compounds of the following formula

[0087]

[0088] - The compounds of formula III are preferably selected from the following formulas:

[0089]

[0090]

[0091] wherein "alkyl" and R 3a have the meanings indicated above, and R 3a preferably represents H or CH3. Particularly preferred are compounds of formula IIIb;

[0092] Very particularly preferred are compounds of formula IIIb-1,

[0093]

[0094] wherein "alkyl" has the meaning indicated above and preferably represents CH3 as well as C2H5 or n-C3H7.

[0095] - The medium preferably additionally contains one or more compounds selected from compounds of the following formulas IV to VIII:

[0096]

[0097] wherein

[0098] R 0 has the meaning indicated in claim 6,

[0099] X 0 represents F, Cl, a mono- or poly-fluorinated alkyl or alkoxy group, having in each case 1 - 6 C atoms, a mono- or poly-fluorinated alkenyl or alkenyloxy group, having in each case 2 - 6 C atoms,

[0100] Y 1-6 each independently of one another represents H or F,

[0101] Z 0 represents -C2H4-, -(CH2)4-, -CH=CH-, -CF=CF-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH2O-, -OCH2-, -COO-, -CF2O- or -OCF2-, and also represents a single bond in formulas V and VI, and

[0102] r represents 0 or 1.

[0103] In the above formulas, X 0Preferably F, Cl or a mono- or poly-fluorinated alkyl or alkoxy group having 1, 2 or 3 C atoms or a mono- or poly-fluorinated alkenyl or alkenyloxy group having 2 or 3 C atoms. X 0 Particularly preferably F, Cl, CF3, CHF2, OCF3, OCHF2, OCHFCF3, OCHFCHF2, OCHFCH2F, OCF2CH3, OCF2CHF2, OCF2CH2F, OCF2CF2CHF2, OCF2CF2CH2F, OCFHCF2CF3, OCFHCF2CHF2, OCH=CF2, OCF=CF2, OCF2CHFCF3, OCF2CF2CF3, OCF2CF2CClF2, OCClFCF2CF3, CF=CF2, CF=CHF, OCH=CF2, OCF=CF2 or CH=CF2.

[0104] In the compounds of formulas IV to VIII, X 0 Preferably represents F or OCF3, and also OCHF2, CF3, CF2H, Cl, OCH=CF2. R 0 Preferably a straight-chain alkyl or alkenyl group having at most 6 C atoms.

[0105] - The compounds of formula IV are preferably selected from the following formulas:

[0106]

[0107] wherein R 0 and X 0 Have the meanings indicated in claim 6.

[0108] In formula IV, R 0 Preferably represents an alkyl group having 1 - 8 C atoms and X 0 Preferably represents F, Cl, OCHF2 or OCF3, and also OCH=CF2. In the compounds of formula IVb, R 0 Preferably represents an alkyl or alkenyl group. In the compounds of formula IVd, X 0 Preferably represents Cl, and also F.

[0109] - The compounds of formula V are preferably selected from formulas Va to Vj,

[0110]

[0111]

[0112] wherein R 0 and X 0 Have the meanings specified in claim 6. Preferably, in formula V, R 0 Represents an alkyl group having 1 - 8 C atoms and X 0represents F, OCF3 or OCH=CF2.

[0113] - The medium contains one or more compounds of formula VI-1,

[0114]

[0115] particularly preferably those selected from the following formulas:

[0116]

[0117]

[0118] wherein R 0 and X 0 have the meanings specified in claim 6. Preferably, R in formula VI 0 represents an alkyl group having 1-8 C atoms and X 0 represents F, as well as CF3 and OCF3.

[0119] - The medium contains one or more compounds of formula VI-2,

[0120]

[0121] particularly preferably those selected from the following formulas:

[0122]

[0123]

[0124] wherein R 0 and X 0 have the meanings specified in claim 6. Preferably, in formula VI, R 0 represents an alkyl group having 1-8 C atoms and X 0 represents F;

[0125] - The medium preferably contains one or more compounds of formula VII, wherein Z 0 represents -CF2O-, -CH2CH2- or -COO-, particularly preferably those selected from the following formulas:

[0126]

[0127] wherein R 0 and X 0 have the meanings specified in claim 6. Preferably, in formula VII, R 0 represents an alkyl group having 1-8 C atoms and X 0 represents F, as well as OCF3 and CF3.

[0128] The compound of formula VIII is preferably selected from the following formulas:

[0129]

[0130] wherein R 0 and X 0 have the meanings specified above. In formula VIII, R 0 preferably represents a straight-chain alkyl group having 1-8 C atoms. X 0 preferably represents F.

[0131] - The medium additionally contains one or more compounds of the following formula:

[0132]

[0133] wherein R 0 、X 0 、Y 1 and Y 2 have the meanings specified above, and

[0134] each independently of one another represents

[0135] wherein rings A and B do not simultaneously represent 1,4-cyclohexylene;

[0136] - The compound of formula IX is preferably selected from the following formulas:

[0137]

[0138]

[0139] wherein R 0 and X 0 have the meanings specified in claim 6. Preferably, in formula IX, R 0 represents an alkyl group having 1-8 C atoms and X 0 represents F. The compound of formula IXa is particularly preferred;

[0140] - The medium additionally contains one or more compounds selected from the following formulas:

[0141]

[0142] wherein R 0 、X 0 and Y 1-4 have the meanings specified in claim 6, and

[0143] each independently of one another represents

[0144] - The compounds of formula X and formula XI are preferably selected from the following formulae:

[0145]

[0146]

[0147] wherein R 0 and X 0 have the meanings specified in claim 6. Preferably, R 0 represents an alkyl group having 1 - 8 C atoms and X 0 represents F. Particularly preferred compounds are those in which Y 1 represents F and Y 2 represents H or F, preferably F.

[0148] - The medium additionally contains one or more compounds of formula XII:

[0149]

[0150] wherein R 1 and R 2 each independently of one another represent an alkyl group, alkenyl group, alkoxy group, oxaalkyl group, fluoroalkyl group or alkenyloxy group, each having at most 9 C atoms, and preferably each independently of one another represent an alkyl group having 1 - 8 C atoms or an alkenyl group having 2 - 8 C atoms.

[0151] Preferred compounds of formula XII are the compounds of the following formula

[0152]

[0153] where

[0154] alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1 - 8 C atoms, and

[0155] alkenyl and alkenyl* each independently of one another represent a straight-chain alkenyl group having 2 - 8 C atoms.

[0156] Particularly preferred are compounds of formula XII-2 and XII-4.

[0157] Particularly preferred compounds of formula XII-2 are compounds of formula XII-2a, formula XII-2b and formula XII-2c:

[0158]

[0159]

[0160] Particularly preferred compounds of formula XII-4 are compounds of formula XII-4a, formula XII-4b and formula XII-4c:

[0161]

[0162] Compounds of formula XII are preferably used in an amount of 3-40% by weight.

[0163] - The medium additionally contains one or more compounds selected from the following formulas:

[0164]

[0165] wherein R 0 , X 0 , Y 1 and Y 2 have the meanings specified in claim 6. Preferably, R 0 represents an alkyl group having 1-8 C atoms and X 0 represents F or Cl;

[0166] - Compounds of formula XIII and formula XIV are preferably selected from the compounds of the following formulas

[0167]

[0168] wherein R 0 and X 0 have the meanings specified in claim 6. R 0 preferably represents an alkyl group having 1-8 C atoms. In the compounds of formula XIII, X 0 preferably represents F or Cl.

[0169] - The medium additionally contains one or more compounds of formula D1, formula D2, formula D3, formula D4 and / or formula D5,

[0170]

[0171]

[0172] wherein Y 1 , Y 2 , R 0 and X 0 have the meanings specified in claim 6. Preferably, R 0 represents an alkyl group having 1-8 C atoms and X 0 represents F.

[0173] Particularly preferred are the compounds of the following formula

[0174]

[0175]

[0176] wherein R 0 has the meaning specified above and preferably represents a straight-chain alkyl group having 1 to 6 C atoms, in particular C2H5, n-C3H7 or n-C5H 11 .

[0177] - The medium additionally contains one or more compounds of formula XVII:

[0178]

[0179] wherein Y 1 , R 1 and R 2 have the meaning specified above. R 1 and R 2 preferably each independently of one another represent an alkyl or alkenyl group having 1 or 2 to 8 C atoms; Y 1 and Y 2 preferably both represent F. Based on the medium, the compound of formula XVII is preferably used in an amount of 3 to 30% by weight.

[0180] - The medium additionally contains one or more compounds of the following formula:

[0181]

[0182] wherein X 0 , Y 1 and Y 2 have the meaning specified in claim 6, and "alkenyl" represents C 2-7 -alkenyl. Particularly preferred is a compound of the following formula:

[0183]

[0184] wherein R 3a has the meaning specified above and preferably represents H;

[0185] - The medium additionally contains one or more tetracyclic compounds selected from formula XIX to formula XXVIII,

[0186]

[0187]

[0188] wherein Y 1-4 , R 0 and X 0 each independently of one another have one of the meanings specified above. X 0 is preferably F, Cl, CF3, OCF3 or OCHF2. R0 Preferably represents an alkyl, alkoxy, oxaalkyl, fluoroalkyl, cycloalkyl or alkenyl group, each having up to 8 C atoms.

[0189] In the compounds of formula XIX to formula XXVIII, R 0 Preferably represents a straight-chain alkyl group. X 0 Is preferably F or OCF3, and CF3. Y 1 And Y 2 Preferably represents Y 1 = F and Y 2 = H or Y 1 = Y 2 = F.

[0190] Particularly preferred compounds of formula XIX to formula XXVIII are the compounds of formula XXV, wherein X 0 Preferably represents F, and OCF3.

[0191] The preferred mixture comprises at least one compound selected from S-1, S-2, S-3 and S-4,

[0192]

[0193] Since these compounds are particularly useful for suppressing the smectic phase of the mixture.

[0194] The medium preferably comprises one or more neutral compounds of the general formula N,

[0195]

[0196] wherein

[0197] R N1 and R N2 Each independently of one another represents an alkyl or alkoxy group having 1 - 15 C atoms, where, additionally, one or more CH2 groups in these groups may each independently of one another be replaced by -C≡C-, -CF2O-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not directly connected to one another, and where, additionally, one or more H atoms may be replaced by halogen,

[0198] Ring A N1 、A N2 and A N3 Each independently of one another represents 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, trans-1,4-cyclohexylene, where, additionally, one or two CH2 groups may be replaced by -O-, or 1,4-cyclohexenylene,

[0199] Z N1 and ZN2 each independently represents a single bond, -CH2CH2-, -COO-, -OCO-, -C≡C-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -CH=CH-

[0200] n represents 0, 1 or 2

[0201] wherein the compound of formula N is different from the compound of formula I

[0202] The following shows preferred compounds of formula N:

[0203]

[0204]

[0205]

[0206]

[0207] wherein

[0208] alkyl and alkyl* each independently represent a straight-chain alkyl group having 1-9 C atoms, preferably 2-6 C atoms, and alkenyl and alkenyl* each independently represent a straight-chain alkenyl group having 2-6 C atoms

[0209] Among the compounds of formula N, compounds of formula N-1, N-2, N-3, N-4, N-8, N-9, N-14, N-15, N-17, N-18, N-19, N-20, N-21, N-22, N-23, N-24, N-25, N-31, N-33 and N-36 are particularly preferred.

[0210] - The medium additionally contains one or more compounds of formula St-1 to formula St-3

[0211]

[0212] wherein R 0 、Y 1 、Y 2 and X 0 have the meanings specified in claim 6. R 0 preferably represents a straight-chain alkyl group, preferably having 1-6 C atoms. X 0 is preferably F, CF3 or OCF3. Y 1 preferably represents F. Y 2 preferably represents F. In addition, it is preferred that Y 1 = F and Y 2Compounds of =H. The compounds of formulae St-1 to St-3 are preferably used in the mixtures according to the invention at a concentration of 3-30% by weight, in particular 5-25% by weight.

[0213] - The medium additionally contains one or more pyrimidine or pyridine compounds of formulae Py-1 to Py-5,

[0214]

[0215]

[0216] where R 0 is preferably a straight-chain alkyl having 2-5 C atoms. x represents 0 or 1, preferably x = 1. Preferred mixtures contain 3-30% by weight, in particular 5-20% by weight, of such pyridine (pyrimidine) compounds.

[0217] - The medium additionally contains one or more compounds selected from the compounds of formulae Y-1, Y-2, Y-3 and Y-4,

[0218]

[0219] where

[0220] R 2A represents H, an alkyl or alkoxy group having 1-15 C atoms, where, additionally, one or more CH2 groups in these groups may each independently of one another be replaced by -CH=CH-, -C≡C-, -CF2O-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not directly linked to one another, and where, additionally, one or more H atoms may be replaced by halogen,

[0221] L 1-4 and L 2 each independently of one another represent F, Cl, CF3 or CHF2, preferably each represents F,

[0222] Z 2 and Z 2’ each independently represent a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF- or -CH=CHCH2O-,

[0223] p represents 0, 1 or 2,

[0224] q represents 0 or 1,

[0225] (O)C v H2v+1 Represents OC v H 2v+1 or C v H 2v+1 , and

[0226] v represents 1 - 6.

[0227] The following shows particularly preferred compounds of formula Y - 1 to formula Y - 4:

[0228]

[0229]

[0230]

[0231]

[0232] wherein

[0233] alkyl and alkyl* each independently of one another represent straight - chain alkyls having 1 - 6 C atoms, and

[0234] alkenyl and alkenyl* each independently of one another represent straight - chain alkenyls having 2 - 6 C atoms.

[0235] Among the compounds shown, compounds of formula Y - 1a, Y - 1c, Y - 1e, Y - 1g, Y - 1j, Y - 1r, Y - 1t, Y - 2b, Y - 2h, Y - 2j and Y - 3a are particularly preferred.

[0236] In the mixture according to the invention, the proportion of compounds of formula Y - 1 to formula Y - 3 is preferably 0 - 30% by weight.

[0237] - The medium additionally contains one or more compounds selected from compounds of formula BC, CR, PH - 1, PH - 2, BF and BS,

[0238]

[0239] wherein

[0240] R B1 , R B2 , R CR1 , R CR2 , R 1 and R 2 each independently of one another have the meaning of R 2A . c is 0, 1 or 2.

[0241] The mixture according to the invention preferably contains compounds of the formula BC, formula CR, formula PH-1, formula PH-2 and / or formula BF in an amount of 0.5 - 20% by weight, in particular 1 - 15% by weight.

[0242] Particularly preferred compounds of the formula BC, formula CR, formula BF and formula BS are compounds BC-1 to BC-7, CR-1 to CR-5, BF-1 to BF-3 and BS-1 to BS-3,

[0243]

[0244]

[0245]

[0246]

[0247] where

[0248] alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1 - 6 C atoms,

[0249] alkenyl and alkenyl* each independently of one another represent a straight-chain alkenyl group having 2 - 6 C atoms, and

[0250] alkoxy and alkoxy* each independently of one another represent a straight-chain alkoxy group having 2 - 6 C atoms.

[0251] A mixture very particularly preferably containing one, two or three compounds of the formula BF-3 and / or formula BS-3 is preferred.

[0252] In the formulae given in the context,

[0253] - preferably represents

[0254]

[0255] -R 0 is preferably a straight-chain alkyl or alkenyl group having 2 - 7 C atoms;

[0256] - In formula I, X 1 is preferably CF3, as well as OCF3;

[0257] - The medium preferably contains one, two or three compounds of formula I;

[0258] - The medium contains CLP-n-T and / or CLP-n-OT, where n represents 2, 3, 4 or 5;

[0259] - The medium contains CLP-n-T, where n represents 2, 3, 4 or 5, and / or CLP-V-n, where n represents 1, 2 or 3, preferably 1;

[0260] - The medium contains CLP-V-T, CLP-nV-T or CLP-Vn-T, where n represents 1 or 2;

[0261] - The medium contains CLP-V-OT, CLP-nV-OT or CLP-Vn-OT, where n represents 1 or 2;

[0262] - The medium contains CLP-nV-m or CLP-Vn-m, where m represents 1 or 2 and n represents 1 or 2;

[0263] - The medium contains CLP-nV2-m, CLP-nV2-T or CLP-nV2-OT, where m represents 1 or 2 and n represents 1 or 2;

[0264] - The medium preferably contains one or more compounds selected from the compounds of formula I, II, III, V, VI-1, VI-2, XII, XIII, XIV, XVII, XXIII, XXV;

[0265] - The medium preferably contains one or more compounds of formula VI-1;

[0266] - The medium preferably contains one or more compounds of formula VI-2;

[0267] - The medium preferably contains 1-30% by weight, preferably 2-20% by weight, particularly preferably 2-15% by weight of the compound of formula I;

[0268] - The proportion of the compounds of formula II-XXVII in the mixture as a whole is preferably 20-99% by weight;

[0269] - The medium preferably contains 25-80% by weight, particularly preferably 30-70% by weight of the compound of formula II and / or formula III;

[0270] - The medium preferably contains 0-70% by weight, particularly preferably 20-60% by weight of the compound of formula IIa-1;

[0271] - The medium preferably contains 0-25% by weight, particularly preferably 5-25% by weight of the compound of formula IIa-2;

[0272] - The medium preferably contains 0-30% by weight, particularly preferably 5-25% by weight of the compound of formula IIa-3;

[0273] - The medium preferably contains 0-25% by weight, particularly preferably 5-25% by weight of the compound of formula IIa-5;

[0274] - The medium preferably contains 5 - 40% by weight, particularly preferably 10 - 30% by weight of the compound of formula V;

[0275] - The medium preferably contains 3 - 30% by weight, particularly preferably 6 - 25% by weight of the compound of formula VI-1;

[0276] - The medium preferably contains 2 - 30% by weight, particularly preferably 4 - 25% by weight of the compound of formula VI-2;

[0277] - The medium preferably contains 5 - 40% by weight, particularly preferably 10 - 30% by weight of the compound of formula XII;

[0278] - The medium preferably contains 1 - 25% by weight, particularly preferably 2 - 15% by weight of the compound of formula XIII;

[0279] - The medium preferably contains 5 - 45% by weight, particularly preferably 10 - 35% by weight of the compound of formula XIV;

[0280] - The medium preferably contains 1 - 20% by weight, particularly preferably 2 - 15% by weight of the compound of formula XVI;

[0281] - The medium preferably contains 5 - 30% by weight, particularly preferably 8 - 22% by weight of the compound of formula Va, wherein X 0 = OCH = CF2;

[0282] - The medium preferably contains the compound of formula CC-3-2V and the compound of formula CC-3-V and / or CC-3-V1;

[0283] - The medium preferably contains the compound of formula CC-3-2V and the compound of formula APUQU-2-F and / or APUQU-3-F;

[0284] - The medium preferably contains the compound CC-3-2V and the compound of formula CC-3-2V1;

[0285] - The medium preferably contains the compound CC-3-2V and the compound of formula PP-1-2V1;

[0286] - The medium preferably contains the compound CC-3-2V and at least one compound of formula PGUQU-n-F, wherein n = 3, 4 or 5;

[0287] - The medium preferably contains the compound CC-3-2V and at least one compound of formula DPGU-n-F, wherein n = 2, 3, 4 or 5.

[0288] It has been found that even a relatively small proportion of the compounds of formula I, but especially when mixed with one or more compounds of formula II to formula XXVIII, leads to a significant reduction in the switching time parameter γ1 / K1. In addition, the liquid crystal media according to the invention are characterized by their relatively high birefringence value and their light stability. At the same time, the mixtures exhibit very good VHR values after exposure to UV.

[0289] In the present application, the expression "alkyl" or "alkyl*" includes straight-chain and branched alkyl groups having 1 - 7 C atoms, especially the straight-chain groups methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl. Groups having 1 - 6 carbon atoms are generally preferred.

[0290] In the present application, the expression "O-alkyl" includes straight-chain and branched alkoxy groups.

[0291] In the present application, the expression "alkenyl" or "alkenyl*" includes straight-chain and branched alkenyl groups having 2 - 7 carbon atoms, especially straight-chain groups. Preferred alkenyl groups are C2-C7-1E-alkenyl, C4-C7-3E-alkenyl, C5-C7-4-alkenyl, C6-C7-5-alkenyl, and C7-6-alkenyl, especially C2-C7-1E-alkenyl, C4-C7-3E-alkenyl, and C5-C7-4-alkenyl. Particularly preferred examples of alkenyl are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl, etc. Groups having at most 5 carbon atoms are generally preferred.

[0292] In the present application, the expression "fluoroalkyl" includes straight-chain groups having at least one fluorine atom (preferably terminal fluorine), i.e., fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl, and 7-fluoroheptyl. However, other positions of fluorine are not excluded.

[0293] In the present application, the expression "oxaalkyl" or "alkoxy" includes groups of the formula C n H 2n+1 -O-(CH2) m wherein n and m each independently of one another represent 1 - 6. m can also represent 0. Preferably, n = 1 and m = 1 - 6 or m = 0 and n = 1 - 3.

[0294] By R in formula I 1 and R 2By appropriate selection of the meaning, the addressing time, threshold voltage, steepness of the transmission characteristic lines, etc. can be changed in the desired manner. For example, compared with alkyl and alkoxy groups, 1E-alkenyl, 3E-alkenyl, 2E-alkenyloxy, etc. generally result in shorter addressing times, improved nematic tendency, and higher elastic constant k 33 (bending) to k 11 (stretching) ratio. Compared with alkyl and alkoxy groups, 4-alkenyl, 3-alkenyl, etc. generally result in lower threshold voltages and lower k 33 / k 11 values. The mixtures according to the invention are characterized in particular by high K1 values and thus significantly faster response times compared to mixtures of the prior art.

[0295] The optimal mixing ratios of the compounds of the above-mentioned formula mainly depend on the desired properties, the choice of the components of the above-mentioned formula, and the choice of any other components that may be present.

[0296] Suitable mixing ratios within the ranges indicated above can be readily determined depending on the circumstances.

[0297] The total amount of the compounds of the above-mentioned formula in the mixtures according to the invention is not critical. Thus, for the purpose of optimizing various properties, the mixtures can contain one or more other components. However, generally, the greater the observed effect on the desired improvement of the mixture properties, the higher the total concentration of the compounds of the above-mentioned formula.

[0298] In a particularly preferred embodiment, the medium according to the invention comprises compounds of formula IV to formula VIII, wherein X 0 represents F, OCF3, OCHF2, OCH═CF2, OCF═CF2 or OCF2-CF2H. The favorable synergistic effect with the compounds of formula I results in particularly favorable properties. In particular, mixtures comprising compounds of formula I and formula VI, or compounds of formula I and formula XI, or compounds of formula I, formula VI and formula XI are characterized by their low threshold voltages.

[0299] The individual compounds of the above-mentioned formula and its sub-formulas that can be used in the media according to the invention are known or can be prepared analogously to known compounds.

[0300] The invention also relates to electro-optical displays, such as TN, STN, TFT, OCB, IPS, PS-IPS, FFS, PS-FFS, positive VA or MLC displays, which have two externally parallel plates (forming a panel together with the frame), integrated non-linear elements on the external plates for switching individual pixels, and a nematic liquid crystal mixture having positive dielectric anisotropy and high specific resistance, which contains a medium of this type, and to the use of these media for electro-optical purposes.

[0301] Furthermore, the mixtures according to the invention are also suitable for positive VA applications, also known as HT-VA applications. These refer to electro-optical displays with an in-plane drive electrode arrangement and a vertically aligned liquid crystal medium having positive dielectric anisotropy. The mixtures according to the invention are particularly preferably suitable for TN-TFT display applications with low operating voltages, i.e., particularly preferably for notebook applications.

[0302] The liquid crystal mixtures according to the invention enable a significant broadening of the accessible parameter range. The achievable combination of clearing point, rotational viscosity and elastic constants, thermal stability and UV stability, and high optical anisotropy far exceeds the previous materials from the prior art.

[0303] The mixtures according to the invention are particularly suitable for automotive applications and high-Δn TFT applications, such as PDAs, notebooks, LCD TVs, and monitors.

[0304] The liquid crystal mixtures according to the invention maintain the nematic phase at temperatures as low as -20 °C and preferably as low as -30 °C, particularly preferably as low as -40 °C, and have a clearing point ≥ 70 °C, preferably ≥ 74 °C, while allowing a rotational viscosity γ1 of ≤ 120 mPa·s, particularly preferably 60 mPa·s, enabling the realization of excellent MLC displays with fast response times.

[0305] The dielectric anisotropy Δε of the liquid crystal mixtures according to the invention is preferably ≥ +2, particularly preferably ≥ +4.

[0306] The birefringence Δn of the liquid crystal mixtures according to the invention is preferably ≥ 0.08, particularly ≥ 0.10.

[0307] The nematic phase range of the liquid crystal mixtures according to the invention preferably has a width of at least 90 °, particularly at least 100 °. This range preferably extends at least from -20 °C to +70 °C.

[0308] If the mixtures according to the invention are used for IPS or FFS applications, the mixtures preferably have a dielectric anisotropy value of 2 - 30 and an optical anisotropy value of 0.07 - 0.13.

[0309] It goes without saying that by appropriately selecting the components of the mixture according to the invention, it is also possible to achieve a higher clearing point (e.g., above 100 °C) at a higher threshold voltage or a lower clearing point at a lower threshold voltage, while maintaining other advantageous properties. When the viscosity is increased only slightly accordingly, it is also possible to obtain a mixture with a higher Δε and thus a low threshold. The MLC display according to the invention is preferably operated at the first Gooch and Tarry transmission minimum [C.H. Gooch and H.A. Tarry, Electron. Lett. 10, 2-4, 1974; C.H. Gooch and H.A. Tarry, Appl. Phys., Vol. 8, 1575-1584, 1975], where, in addition to particularly advantageous electro-optical properties (such as a high slope of the characteristic line and a low angular dependence of the contrast) (German Patent 30 22 818), a lower dielectric anisotropy is sufficient at the same threshold voltage as in a similar display at the second minimum. This enables a significantly higher specific resistance value to be achieved when using the mixture according to the invention at the first minimum compared to the case of a mixture containing a cyanide compound. By appropriately selecting the individual components and their weight ratios, a person skilled in the art can set the birefringence required for a pre-specified layer thickness of the MLC display using simple conventional methods.

[0310] The structure of the polarizer, electrode substrate, and surface-treated electrode of the MLC display according to the invention corresponds to the usual design of displays of this type. Here, the term "usual design" is broadly depicted and also includes all derivatives and improvements of MLC displays, particularly including matrix display elements based on polysilicon TFTs or MIMs.

[0311] However, a significant difference between the display according to the invention and conventional displays based on twisted nematic panels to date lies in the selection of the liquid crystal parameters of the liquid crystal layer.

[0312] The liquid crystal mixture that can be used according to the invention is prepared in a manner conventional per se, for example, by mixing one or more compounds of formula I with one or more compounds of formula II to XXVII or with other liquid crystal compounds and / or additives. Generally, the required amounts of the components to be used in smaller amounts are advantageously dissolved in the components constituting the main component, preferably at an elevated temperature. It is also possible to mix solutions of the components dissolved in an organic solvent (e.g., dissolved in acetone, chloroform, or methanol), and after thorough mixing, the solvent is removed again, for example, by distillation.

[0313] The dielectric can also include other additives known to a person skilled in the art and described in the literature, such as UV stabilizers, for example, those of Ciba Chemicals In particular 770, antioxidants, radical scavengers, nanoparticles, etc. For example, 0-15% of a dichroic dye or a chiral dopant can be added. Suitable stabilizers and dopants are mentioned in Tables C and D below.

[0314] To increase the anchoring force, a polymerizable compound, so-called "reactive liquid crystal", can also be additionally added to the mixture according to the invention. Preferred polymerizable compounds are listed in Table E.

[0315] The following examples are intended to explain the invention and not to limit it. In the context, percentage data represent weight percentages and all temperatures are in degrees Celsius.

[0316] Throughout this application, the 1,4-cyclohexylene ring and the 1,4-phenylene ring are represented as follows:

[0317]

[0318] The cyclohexylene ring is a trans-1,4-cyclohexylene ring.

[0319] Throughout this application and the working examples, the structures of the liquid crystal compounds are indicated by abbreviations. Unless otherwise stated, they are converted to chemical formulas according to Tables 1-3. All groups C n H 2n+1 C m H 2m+1 C m’ H 2m’+1 C n H 2n C m H 2m are straight-chain alkyl or alkenyl groups, each having n, m, m' or z carbon atoms in each case, where n, m, m' and z each independently of one another represent 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, preferably 1, 2, 3, 4, 5 or 6. The ring units of the compounds are encoded in Table 1, the bridging units are listed in Table 2 and the symbols of the left- and right-hand side chains of the compounds are explained in Table 3.

[0320] Table 1: Ring units

[0321]

[0322]

[0323]

[0324] Table 2: Bridging units

[0325]

[0326] Table 3: Side chains

[0327]

[0328]

[0329] Preferred mixture components are shown in Tables A and B.

[0330] Table A

[0331]

[0332]

[0333] Table B

[0334] (n = 1 - 15; (O)C n H 2n+1 refers to C n H 2n+1 or OC n H 2n+1 )

[0335]

[0336]

[0337]

[0338]

[0339]

[0340]

[0341]

[0342]

[0343]

[0344]

[0345] Particularly preferred are liquid crystal mixtures which, in addition to the compound of formula I, contain at least one, two, three, four or more compounds from Table B.

[0346] Table C illustrates possible dopants which are usually added to the mixtures according to the invention. The mixtures preferably contain 0 - 10% by weight, in particular 0.001 - 5% by weight and particularly preferably 0.001 - 3% by weight of dopant.

[0347] Table C

[0348]

[0349]

[0350] Table D

[0351] The stabilizers that can be added to the mixture according to the invention are mentioned below, for example, in an amount of 0-10% by weight.

[0352]

[0353] n = 1, 2, 3, 4, 5, 6 or 7

[0354]

[0355] n = 1, 2, 3, 4, 5, 6 or 7

[0356]

[0357] n = 1, 2, 3, 4, 5, 6 or 7

[0358]

[0359]

[0360]

[0361]

[0362]

[0363] Table E

[0364] Table E shows example compounds that can be used in the LC medium according to the invention, preferably as reactive liquid crystal compounds. If the mixture according to the invention contains one or more reactive compounds, they are preferably used in an amount of 0.01-5% by weight. It may also be necessary to add an initiator or a mixture of two or more initiators for polymerization. The initiator or initiator mixture is preferably added in an amount of 0.001-2% by weight based on the mixture. Suitable initiators are, for example, Irgacure (BASF) or Irganox (BASF).

[0365]

[0366]

[0367]

[0368]

[0369]

[0370]

[0371]

[0372]

[0373]

[0374]

[0375]

[0376]

[0377]

[0378]

[0379] In a preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds, preferably selected from the polymerizable compounds of formulae RM-1 to RM-94. This type of medium is particularly suitable for PS-FFS and PS-IPS applications. Among the reactive liquid crystals mentioned in Table E, compounds RM-1, RM-2, RM-3, RM-4, RM-5, RM-11, RM-17, RM-35, RM-41, RM-44, RM-62, RM-81 and RM-99 are particularly preferred. Examples

[0380] The following working examples are intended to illustrate the invention and not to limit it.

[0381] In the context, percentage data represent weight percentages. All temperatures are indicated in degrees Celsius. m.p. represents the melting point, cl.p. = the clearing point. Furthermore, C = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The data between these symbols represent the transition temperatures. Furthermore,

[0382] V o represents the threshold voltage, capacitive [V], at 20 °C,

[0383] Δn represents the optical anisotropy measured at 20 °C and 589 nm,

[0384] Δε represents the dielectric anisotropy at 20 °C and 1 kHz,

[0385] cp. represents the clearing point [℃]

[0386] K1 represents the elastic constant, "splay" deformation at 20℃, [pN],

[0387] K3 represents the elastic constant, "bend" deformation at 20℃, [pN],

[0388] γ1 represents the rotational viscosity at 20℃ [mPa·s], measured by the transient current method in a magnetic field

[0389] LTS represents the low temperature stability (nematic phase), measured in a glass bottle.

[0390] Mixture examples

[0391] Unless otherwise explicitly stated, the electro-optical data are measured at 20℃ in a TN panel at the first minimum (i.e., at a d·Δn value of 0.5μm). Unless otherwise explicitly specified, the optical data are measured at 20℃. Unless otherwise explicitly stated, all physical properties are determined in accordance with "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status November 1997, Merck KGaA, Germany and carried out at 20℃.

[0392] Example M1

[0393]

[0394] Example M2

[0395]

[0396] Example M3

[0397]

[0398] Example M4

[0399]

[0400] Example M5

[0401]

[0402]

[0403] Example M6

[0404]

[0405] Example M7

[0406]

[0407] Example M8

[0408]

[0409]

[0410] Example M9

[0411]

[0412] Example M10

[0413]

[0414] Example M11

[0415]

[0416] Example M12

[0417]

[0418] Example M13

[0419]

[0420] Example M14

[0421]

[0422] Example M15

[0423]

[0424]

[0425] Example M16

[0426]

[0427] Example M17

[0428]

[0429] Example M18

[0430]

[0431]

[0432] Example M19

[0433]

[0434] Example M20

[0435]

[0436] Example M21

[0437]

[0438] Example M22

[0439]

[0440]

[0441] Example M23

[0442]

[0443] Example M24

[0444]

[0445] Example M25

[0446]

[0447]

[0448] Example M26

[0449]

[0450] Example M26a

[0451] The liquid crystal mixture M26 is additionally stabilized with 300 ppm of the compound of formula ST-2

[0452] 300 ppm of

[0453] Example M27

[0454]

[0455] Example M27a

[0456] The liquid crystal mixture M27 is additionally stabilized with 300 ppm of the compound of formula ST-2

[0457] 300 ppm of

[0458] Example M28

[0459]

[0460] Example M28a

[0461] The liquid crystal mixture M28 is additionally stabilized with 400 ppm of the compound of formula ST-1 and 1000 ppm of the compound of formula ST-2

[0462] 400 ppm of

[0463] and

[0464] 1000 ppm of

[0465] Example M29

[0466]

[0467]

[0468] Example M29a

[0469] The liquid crystal mixture M29 is additionally stabilized with 400 ppm of the compound of formula ST-1 and 1000 ppm of the compound of formula ST-2

[0470] 400 ppm of

[0471] and

[0472] 1000 ppm of

[0473] Example M30

[0474]

[0475] Example M30a

[0476] The liquid crystal mixture M30 is additionally stabilized with 400 ppm of the compound of formula ST-1 and 1000 ppm of the compound of formula ST-2

[0477] 400 ppm of

[0478] and

[0479] of 1000 ppm

[0480] Example M31

[0481]

[0482] Example M31a

[0483] The liquid crystal mixture M31 is additionally stabilized with 400 ppm of the compound of formula ST-1 and 1000 ppm of the compound of formula ST-2

[0484] of 400 ppm

[0485] and

[0486] of 1000 ppm

[0487] Example M32

[0488]

[0489] Example M33

[0490]

[0491] Example M34

[0492]

[0493]

[0494] Example M35

[0495]

[0496] Example M36

[0497]

[0498]

[0499] Example M37

[0500]

[0501] Example M38

[0502]

[0503] Example M39

[0504]

[0505]

[0506] Example M40

[0507]

[0508] The liquid crystal mixture M40 is additionally stabilized with 400 ppm of the compound of formula ST-1 and various concentrations of the compound of formula ST-2 or formula ST-3:

[0509]

[0510]

[0511] Mixture ST-1 ST-2 ST-3 Example M40a 400 ppm - - Example M40b 400 ppm 100 ppm - Example M40c 400 ppm 500 ppm - Example M40d 400 ppm 1000 ppm - Example M40e 400 ppm - 100 ppm Example M40f 400 ppm - 500 ppm Example M40g 400 ppm - 1000 ppm

[0512] Example M41

[0513]

[0514] Example M42

[0515]

[0516]

[0517] Example M43

[0518]

[0519] Example M44

[0520]

[0521] Example M45

[0522]

[0523] Example M46

[0524]

[0525] Example M47

[0526]

[0527]

[0528] Example M48

[0529]

[0530] Example M49

[0531]

[0532] Example M50

[0533]

[0534]

[0535] The liquid crystal mixture M50 is additionally stabilized with 400 ppm of the compound of formula ST-1 and various concentrations of the compound of formula ST-2 or formula ST-3:

[0536] Mixture ST-1 ST-2 ST-3 Example M50a 400 ppm - - Example M50b 400 ppm 100 ppm - Example M50c 400 ppm 500 ppm - Example M50d 400 ppm 1000 ppm - Example M50e 400 ppm - 100 ppm Example M50f 400 ppm - 500 ppm Example M50g 400 ppm - 1000 ppm

[0537] Example M51

[0538]

[0539] The liquid crystal mixture M51 is additionally stabilized with 400 ppm of the compound of formula ST-1 and various concentrations of the compound of formula ST-2 or formula ST-3:

[0540] Mixture ST-1 ST-2 ST-3 Example M51a 400 ppm - - Example M51b 400 ppm 100 ppm - Example M51c 400 ppm 500 ppm - Example M51d 400 ppm 1000 ppm - Example M51e 400 ppm - 100 ppm Example M51f 400 ppm - 500 ppm Example M51g 400 ppm - 1000 ppm

[0541] Example M52

[0542]

[0543]

[0544] Example M53

[0545]

[0546] Example M54

[0547]

[0548] Example M55

[0549]

[0550]

[0551] The liquid crystal mixture M55 is additionally stabilized with 0.05% of the compound of formula ST-1

[0552]

[0553] Example M56

[0554]

[0555] The liquid crystal mixture M56 is additionally stabilized with 0.05% of the compound of formula ST-1

[0556]

[0557] Example M57

[0558]

[0559]

[0560] Example M58

[0561]

[0562] Example M59

[0563]

[0564] The liquid crystal mixture M59 is additionally stabilized with 0.04% of the compound of formula ST-1

[0565]

[0566] Example M60

[0567]

[0568]

[0569] The liquid crystal mixture M60 is additionally stabilized with 0.04% of the compound of formula ST-1

[0570]

[0571] Example M61

[0572]

[0573] The liquid crystal mixture M61 is additionally stabilized with 0.04% of the compound of formula ST-1

[0574]

[0575] Example M62

[0576]

[0577]

[0578] The liquid crystal mixture M62 is additionally stabilized with 0.04% of the compound of formula ST-1

[0579]

[0580] Example M63

[0581]

[0582] The liquid crystal mixture M63 is additionally stabilized with 0.04% of the compound of formula ST-1

[0583]

[0584] Example M64

[0585]

[0586]

[0587] Example M65

[0588]

[0589] Example M66

[0590]

[0591] Example M67

[0592]

[0593] Example M68

[0594]

[0595]

[0596] Example M69

[0597]

[0598] Example M70

[0599]

[0600] Example M71

[0601]

[0602]

[0603] Example M72

[0604]

[0605] Example M73

[0606]

[0607] Example M74

[0608]

[0609]

[0610] Example M75

[0611]

[0612] Example M76

[0613]

[0614] Example M77

[0615]

[0616]

[0617] Example M78

[0618]

[0619] Example M79

[0620]

[0621] Example M80

[0622]

[0623]

[0624] Example M81

[0625]

[0626] Example M82

[0627]

[0628] Example M83

[0629]

[0630]

[0631] Example M84

[0632]

[0633] Example M85

[0634]

[0635] Example M86

[0636]

[0637] Example M87

[0638]

[0639]

[0640] Example M88

[0641]

[0642] Example M89

[0643]

[0644] Example M90

[0645]

[0646]

[0647] Example M91

[0648]

[0649] Example M92

[0650]

[0651] Example M93

[0652]

[0653] Example M94

[0654]

[0655]

[0656] Example M95

[0657]

[0658] Example M96

[0659]

[0660] Example M97

[0661]

[0662] Example M98

[0663]

[0664] Example M99

[0665]

[0666] Example M100

[0667]

[0668] Example M101

[0669]

[0670]

[0671] Example M102

[0672]

[0673] Example M103

[0674]

[0675] Example M104

[0676]

[0677] Example M105

[0678]

[0679]

[0680] Example M106

[0681]

[0682] Example M107

[0683]

[0684] Example M108

[0685]

[0686]

[0687] Example M109

[0688]

[0689] Example M110

[0690]

[0691] Example M111

[0692]

[0693] Example M112

[0694]

[0695] Example M113

[0696]

[0697] Example M114

[0698]

[0699] Example M115

[0700]

[0701]

[0702] Example M116

[0703]

[0704] Example M117

[0705]

[0706] The liquid crystal mixture M117 is additionally stabilized with 0.05% of the compound of formula ST-1

[0707]

[0708] Example M118

[0709]

[0710] The liquid crystal mixture M118 is additionally stabilized with 0.05% of the compound of formula ST-1

[0711]

[0712] Example M119

[0713]

[0714] The liquid crystal mixture M119 is additionally stabilized with 0.04% of the compound of formula ST-1 and 0.02% of the compound of formula ST-3

[0715]

Claims

1. A liquid crystal medium having positive dielectric anisotropy, characterized in that it contains 1 to 30% by weight of one or more compounds of formula I, One or more compounds of formula I are selected from the following groups 1) to 6): Group 1): CLP-n-T and CLP-n-OT, where n represents 2, 3 or 4; Group 2): CLP-n-T, where n represents 2, 3 or 4, and CLP-V-n, where n represents 1, 2 or 3; Group 3): CLP-V-T, CLP-nV-T or CLP-Vn-T, where n represents 1 or 2; Group 4): CLP-V-OT, CLP-nV-OT or CLP-Vn-OT, where n represents 1 or 2; Group 5): CLP-nV-m or CLP-Vn-m, where m represents 1 or 2 and n represents 1 or 2; or Group 6): CLP-nV2-m, CLP-nV2-T or CLP-nV2-OT, where m represents 1 or 2 and n represents 1 or 2; Among them, The structure of CLP-n-T is: The structure of CLP-n-OT is: The structure of CLP-V-n is: The structure of CLP-V-T is: The structure of CLP-nV-T is: The structure of CLP-Vn-T is: The structure of CLP-V-OT is: The structure of CLP-nV-OT is: The structure of CLP-Vn-OT is: The structure of CLP-nV-m is: The structure of CLP-Vn-m is: The structure of CLP-nV2-m is: The structure of CLP-nV2-T is: The structure of CLP-nV2-OT is: wherein the liquid crystal medium does not contain a cyano compound; wherein the liquid crystal medium further contains one or more neutral compounds selected from formula N-1 to formula N-36, where alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1-9 C atoms, and alkenyl and alkenyl* each independently of one another represent a straight-chain alkenyl group having 2-6 C atoms; wherein the liquid crystal medium further contains one or more tetracyclic compounds selected from formula X, formula XI, formula XIX to formula XXVIII, where R 0 represents an alkyl or alkoxy group having 1 to 15 carbon atoms, wherein one or more CH2 groups in these groups may each be independently replaced by -C≡C-, -CF2O-, -CH=CH-, -◇-,-◇◇-,-O-,-CO-O- or -O-CO- in such a way that O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen, a cycloalkyl group having 3 to 6 carbon atoms, X 0 represents F, Cl, a mono-fluorinated or poly-fluorinated alkyl or alkoxy group having 1 to 6 C atoms, a mono-fluorinated or poly-fluorinated alkenyl or alkenyloxy group having 2 to 6 C atoms, Y 1-4 each independently represents H or F, and Each independently represents The liquid crystal medium additionally contains 30-80% by weight of one or more compounds of formula II, wherein the liquid crystal medium contains 20-60% by weight of a compound of formula IIa-1 and 0-25% by weight of a compound of formula IIa-2; where A represents 1,4-phenylene or trans-1,4-cyclohexylene, a represents 0 or 1, R 3 represents an alkenyl group having 2 to 9 carbon atoms, and R 4 represents an alkyl or alkoxy group having 1 to 15 C atoms, wherein one or more CH2 groups in these groups may each independently of one another be replaced by -C≡C-, -CF2O-, -CH=CH-, -◇-,-◇◇-,-O-, -CO-O- or -O-CO- in such a way that O atoms are not directly linked to one another, and wherein one or more H atoms may be replaced by halogen.

2. The liquid crystal medium according to claim 1, characterized in that the liquid crystal medium additionally contains one or more compounds of formula III, where R 3 represents an alkenyl group having 2 to 9 C atoms, and R 4 represents an alkyl or alkoxy group having 1 to 15 carbon atoms, wherein One or more CH2 groups in these groups can each independently of one another be replaced by -C≡C-, -CF2O-, -CH=CH-, -◇-,-◇◇-,-O-, -CO-O- or -O-CO- in such a way that O atoms are not directly connected to one another, and where one or more H atoms can be replaced by a halogen.

3. The liquid crystal medium according to claim 1, characterized in that the compound of formula II is selected from the following compounds, wherein R 3a and R 4a each independently of the other represents H, CH3, C2H5 or C3H7, and "alkyl" represents a straight-chain alkyl group having 1 to 8 C atoms.

4. The liquid crystal medium according to claim 1, characterized in that it additionally contains one or more compounds selected from compounds of formula IV to formula VIII, where R 0 represents an alkyl or alkoxy group having 1 to 15 carbon atoms, wherein One or more CH2 groups in these groups may each independently of one another be replaced by -C≡C-, -CF2O-, -CH=CH-, -◇-,-◇◇-,-O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to one another, and wherein, one or more H atoms may be replaced by halogen, cycloalkyl having 3 - 6 C atoms, X 0 represents F, Cl, a mono-fluorinated or poly-fluorinated alkyl or alkoxy group having 1 to 6 C atoms, a mono-fluorinated or poly-fluorinated alkenyl or alkenyloxy group having 2 to 6 C atoms Y 1-6 Each independently represents H or F, Z 0 represents -C2H4-, -(CH2)4-, -CH=CH-, -CF=CF-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH2O-, -OCH2-, -COO-, -CF2O- or -OCF2-, also represents a single bond in Formulas V and VI, and r represents 0 or 1.

5. The liquid crystal medium according to claim 1, characterized in that it additionally contains one or more compounds selected from the compounds of formulae Va to Vj, wherein R 0 and X 0 have the meanings specified in claim 4.

6. The liquid crystal medium according to claim 1, characterized in that it additionally contains one or more compounds selected from the compounds of formulae VI-1a to VI-1d, wherein R 0 and X 0 have the meanings specified in claim 4.

7. The liquid crystal medium according to claim 1, characterized in that it additionally contains one or more compounds selected from the compounds of formulae VI-2a to VI-2f, wherein R 0 and X 0 have the meanings specified in claim 4.

8. The liquid crystal medium according to claim 1, characterized in that it additionally contains one or more compounds selected from the compounds of formula XII, wherein R 1 and R 2 each independently represents an alkyl, alkenyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyloxy group each having at most 9 carbon atoms.

9. The liquid crystal medium according to claim 1, characterized in that it additionally contains one or more compounds selected from the compounds of formulae XIII to XVI, wherein R 0 , X 0 , Y 1 and Z 2 have the meanings specified in claim 4.

10. The liquid crystal medium according to claim 1, characterized in that the compound of formula II is selected from the following compounds, 11. The liquid crystal medium according to claim 1, characterized in that it additionally contains one or more compounds selected from the compounds of formulae D1, D2, D3, D4 and D5, where Y 1 、Y 2 、R 0 and X 0 have the meanings specified in claim 4.

12. The liquid crystal medium according to claim 1, characterized in that it additionally contains one or more compounds selected from the compounds of formulae Y-1, Y-2, Y-3 and Y-4, wherein R 2A represents H, an alkyl or alkoxy group having 1 to 15 C atoms, wherein One or more CH2 groups in these groups may each independently of one another be replaced by -CH=CH-, -C≡C-, -CF2O-, -CH=CH-, -◇-,-◇◇-,-O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to one another, and wherein, one or more H atoms may be replaced by halogen, and L 1 and L 2 each independently represents F, Cl, CF3 or CHF2, Z 2 and Z 2’ each independently represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF- or -CH=CHCH2O- p represents 0, 1 or 2, q represents 0 or 1, (O)C v H 2v+1 Represents OC v H 2v+1 or C v H 2v+1 and v represents 1 - 6.

13. The liquid crystal medium according to claim 12, characterized in that L 1 and L 2 each represent F.

14. The liquid crystal medium according to claim 1, characterized in that it additionally contains one or more compounds selected from the compounds of formulae BC, CR, PH-1, PH-2, BF and BS, wherein R B1 、R B2 、R CR1 、R CR2 、R 1 and R 2 each independently of one another represent H, an alkyl or alkoxy group having 1 - 15 C atoms, where One or more CH2 groups in these groups may each independently of one another be replaced by -CH=CH-, -C≡C-, -CF2O-, -CH=CH-, -◇-,-◇◇-,-O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to one another, and wherein one or more H atoms may be replaced by halogen, and c represents 0, 1 or 2.

15. The liquid crystal medium according to claim 1, characterized in that it additionally contains one or more UV stabilizers and / or antioxidants.

16. The liquid crystal medium according to claim 1, characterized in that it additionally contains one or more polymerizable compounds.

17. The liquid crystal medium according to claim 1, characterized in that alkyl and alkyl* each independently of one another represent straight-chain alkyl groups having 2 to 6 C atoms.

18. The liquid crystal medium according to claim 1, characterized in that the liquid crystal medium additionally comprises one or more compounds of the following formula XVII: wherein R 1 and R 2 have the meanings specified in claim 8, Y 1 and Y 2 have the meanings specified in claim 4.

19. The liquid crystal medium according to claim 1, characterized in that the liquid crystal medium additionally comprises a stabilizer selected from the following:

20. The liquid crystal medium according to claim 11, characterized in that formula D3 is DPGU-4-F:

21. The liquid crystal medium according to claim 1, characterized in that The liquid crystal medium comprises at least one compound selected from the following:

22. A process for preparing a liquid crystal medium according to any one of claims 1 to 21, characterized in that one or more compounds of formula I are mixed with at least one other liquid crystal compound and optionally with one or more additives and / or one or more polymerizable compounds.

23. Use of a liquid crystal medium according to any one of claims 1 to 21 for electro-optical purposes.

24. Use of the liquid crystal medium according to claim 23, for TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS and PS-FFS displays, shutter glasses for 3D effects, LC lenses and positive VA displays.

25. An electro-optical liquid crystal display containing a liquid crystal medium according to any one of claims 1 to 21.

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