Liquid crystal medium

Abstract

The present invention relates to liquid crystal dielectrics, in particular to compounds of formula I where R 1 and X 1 have the meanings specified in claim 1, and to liquid crystal dielectrics comprising at least one compound of formula I, and also to the use of compounds of formula I 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 No. 201610841375.X, and the invention title of "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 this 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 the 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 fields for the media according to the present invention.

[0004] Liquid crystal materials must have good chemical and thermal stability as well as good stability against 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 in the cell.

[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 well with each other. Depending on the type of cell and the application field, 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 nonlinear 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 a single pixel 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 the 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 usually 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. 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, semi-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 already known simple reflective TN display, 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 in the usually conventional transmissive TFT-TN displays, in order to achieve a low optical retardation (d·Δn), a liquid crystal 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 a liquid crystal 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, a display with a fast response time is required. If a liquid crystal medium with a low viscosity value (especially the rotational viscosity γ 1 ) and a high optical anisotropy (Δn) is used, such a short response time can be achieved in particular.

[0018] To achieve a 3D effect via shutter glasses, a fast-switching mixture with a low rotational viscosity and a correspondingly high optical anisotropy (Δn) is particularly used. The use of a mixture 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] - Extended nematic range (especially down to low temperatures)

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

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

[0023] - Low threshold voltage.

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

[0025] In the case of a supertwisted (STN) panel, it is desirable for the medium to promote greater multiplexability and / or a lower threshold voltage and / or a 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 performances 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 γ 1 and the elastic constants. 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 an increase in the elastic constants, 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 results in 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 from the prior art usually also have a high rotational viscosity, 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 performances (such as a high VHR (voltage holding ratio)) without exhibiting these performances or only exhibiting these performances to a lesser extent. Summary of the Invention

[0028] The object of the present invention is to provide a medium having the above-mentioned desired performances and not exhibiting the above-mentioned disadvantages or only exhibiting the above-mentioned disadvantages 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. Additionally, 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, furthermore, one or more CH 2 groups in these groups can each independently of one another be replaced by -C≡C-, -CF 2 O-, -CH=CH-, -◇-,-◇◇-,-O-, -CO-O- or -O-CO- in such a way that O atoms are not directly linked to one another, and where, furthermore, one or more H atoms can be replaced by halogen, and

[0034] X 1 represents an alkyl group having 1 - 5 C atoms, OCF 3 、CF 3 、CHF 2 、OCHF 2 、OCF 2 CF 3 、CCF 2 CHFCF 3 、OCF=CF 2 、OCH=CF 2 or F.

[0035] The compounds of formula I lead to 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 down to -20 °C and do not exhibit a tendency to crystallize. The rotational viscosity γ 1 is generally < 120 mPa·s. Furthermore, the mixtures according to the invention are characterized by a very good ratio of rotational viscosity γ 1 to the clearing point, a low γ 1 / K 11 value, which results in a faster response time as well as a high clearing point and a wide nematic 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 liquid crystal dielectrics; 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 mixture according to the invention supports a good black state of the display due to the high elastic constant, which is crucial for the contrast of the display, and at the same time promotes a very good response time.

[0037] In the compounds of formula I and the sub-formulae, R 1 preferably represents a straight-chain alkyl group, in particular having 3 to 5 C atoms. In a further preferred embodiment, one or more CH 2 groups in the alkyl group can also be replaced by -CH=CH-.

[0038] The following show 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 to 5 C atoms.

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

[0043] The following show 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 CH 3 or C 2 H 5 , in particular CH3 。

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

[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 that are known and suitable for the said reaction. Variants that 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 the compounds of formula I, R 1 denotes an alkyl and / or an alkoxy group, which can 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 1 denotes one of the CH 2An alkyl group in which the group 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 mono-substituted by a halogen, the group is preferably straight-chain and the halogen is preferably F or Cl. In the case of multi-substitution, the halogen is preferably F. The resulting groups also include perfluorinated groups. In the case of mono-substitution, the fluorine or chlorine substituent may be at any desired position, but is preferably at the ω-position.

[0061] X 1 preferably represents an alkyl group, particularly CH 3 and CF 3 , and OCF 3 .

[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] R3 represents an alkenyl group having 2 to 9 carbon atoms,

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

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

[0073]

[0074] wherein R 3a and R 4a each independently of one another represent H, CH 3 , C 2 H 5 or C 3 H 7 , and "alkyl" represents a straight-chain alkyl group having 1 to 8 carbon atoms. Compounds of formula IIa and formula IIf are particularly preferred, especially those wherein R 3a represents H or CH 3 , and the compound of formula IIc, especially those wherein R 3a and R 4a represent H, CH 3 or C 2 H 5 .

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

[0076]

[0077] A very particularly preferred compound of formula IIa is the compound of the following formula

[0078]

[0079]

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

[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] The preferred concentration is 5 - 70% by weight, in particular 10 - 65% by weight and very particularly preferably 20 - 55% by weight, based on the mixture.

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

[0085]

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

[0087]

[0088] - 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 CH 3 . 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 CH 3 and C 2 H 5 or n - C 3 H 7 .

[0095] - The medium preferably additionally contains one or more compounds selected from compounds of 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 - fluorinated or poly - fluorinated alkyl or alkoxy group, in each case having 1 - 6 C atoms, a mono - fluorinated or poly - fluorinated alkenyl or alkenyloxy group, in each case having 2 - 6 C atoms,

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

[0101] Z 0 represents -C 2 H 4 -, -(CH 2 ) 4 -, -CH=CH-, -CF=CF-, -C 2 F 4 -, -CH 2 CF 2 -, -CF 2 CH 2 -, -CH 2 O-, -OCH 2 -, -COO-, -CF 2 O- or -OCF 2 -, also represents a single bond in Formulas V and VI, and

[0102] r represents 0 or 1.

[0103] In the above formulas, X 0 is preferably F, Cl or a mono-fluorinated or poly-fluorinated alkyl or alkoxy group having 1, 2 or 3 C atoms or a mono-fluorinated or poly-fluorinated alkenyl or alkenyloxy group having 2 or 3 C atoms. X 0 is particularly preferably F, Cl, CF 3 , CHF 2 , OCF 3 , OCHF 2 , OCHFCF 3 , OCHFCHF 2 , OCHFCH 2 F, OCF 2 CH 3 , OCF 2 CHF 2 , OCF 2 CH 2 F, OCF 2 CF 2 CHF 2 , OCF 2 CF 2 CH 2 F, OCFHCF 2 CF 3 , OCFHCF 2 CHF 2 , OCH=CF 2 , OCF=CF 2 , OCF 2 CHFCF 3 , OCF 2 CF 2 CF 3 , OCF2 CF 2 CClF 2 、OCClFCF 2 CF 3 、CF=CF 2 、CF=CHF、OCH=CF 2 、OCF=CF 2 or CH=CF 2 。

[0104] In the compounds of Formulas IV to VIII, X 0 preferably represents F or OCF 3 , and OCHF 2 、CF 3 、CF 2 H、Cl、OCH=CF 2 。R 0 is preferably a straight-chain alkyl or alkenyl having up to 6 carbon 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 having 1 - 8 carbon atoms and X 0 preferably represents F, Cl, OCHF 2 or OCF 3 , and OCH=CF 2 。In the compounds of Formula IVb, R 0 preferably represents an alkyl or alkenyl. In the compounds of Formula IVd, X 0 preferably represents Cl, and 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 having 1 - 8 carbon atoms and X 0 represents F, OCF 3 or OCH=CF 2 。

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

[0114]

[0115] 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, and CF 3 and OCF 3 .

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

[0120]

[0121] 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 comprises one or more compounds of formula VII, wherein Z 0 represents -CF 2 O-, -CH 2 CH 2 -, or -COO-, 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, and OCF3 and CF 3 .

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

[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 each independently represents wherein rings A and B do not simultaneously represent 1,4-cyclohexylene;

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

[0135]

[0136]

[0137] 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;

[0138] - The medium additionally contains one or more compounds selected from the following formulae:

[0139]

[0140] wherein R 0 , X 0 and Y 1-4 have the meanings specified in claim 6, and

[0141] each independently represents

[0142] - The compounds of formula X and formula XI are preferably selected from the following formulae:

[0143]

[0144]

[0145] 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.

[0146] - The medium additionally contains one or more compounds of formula XII:

[0147]

[0148] 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.

[0149] Preferred compounds of formula XII are the compounds of the following formula

[0150]

[0151] wherein

[0152] alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1 - 8 C atoms, and

[0153] alkenyl and alkenyl* each independently of one another represent a straight-chain alkenyl group having 2 - 8 C atoms.

[0154] Particularly preferred are compounds of formula XII-2 and XII-4.

[0155] Particularly preferred compounds of formula XII-2 are compounds of formula XII-2a, formula XII-2b and formula XII-2c:

[0156]

[0157]

[0158] Particularly preferred compounds of formula XII-4 are compounds of formula XII-4a, formula XII-4b and formula XII-4c:

[0159]

[0160] Compounds of formula XII are preferably used in an amount of 3-40% by weight.

[0161] - The medium additionally contains one or more compounds selected from the following formulas:

[0162]

[0163] 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;

[0164] - Compounds of formula XIII and formula XIV are preferably selected from the compounds of the following formulas

[0165]

[0166] 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.

[0167] - The medium additionally contains one or more compounds of formula D1, formula D2, formula D3, formula D4 and / or formula D5,

[0168]

[0169]

[0170] 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.

[0171] Particularly preferred are the compounds of the following formula

[0172]

[0173]

[0174] wherein R 0 has the meaning specified above and preferably represents a straight-chain alkyl group having 1 to 6 C atoms, especially C 2 H 5 -, n-C 3 H 7 or n-C 5 H 11 .

[0175] - The medium additionally contains one or more compounds of formula XVII:

[0176]

[0177] 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 - 30% by weight.

[0178] - The medium additionally contains one or more compounds of the following formula:

[0179]

[0180] wherein X 0 , Y 1 and Y 2 have the meaning specified in claim 6, and "alkenyl" represents C 2-7 -alkenyl. Particularly preferred are compounds of the following formula:

[0181]

[0182] wherein R 3a has the meaning specified above and preferably represents H;

[0183] - The medium additionally contains one or more tetracyclic compounds selected from formula XIX to formula XXVIII,

[0184]

[0185]

[0186] wherein Y 1-4 , R 0 and X 0Each independently has one of the meanings specified above. X 0 is preferably F, Cl, CF 3 , OCF 3 or OCHF 2 . R 0 preferably represents an alkyl, alkoxy, oxaalkyl, fluoroalkyl, cycloalkyl or alkenyl group, each having up to 8 C atoms.

[0187] In the compounds of formula XIX to formula XXVIII, R 0 preferably represents a straight-chain alkyl group. X 0 is preferably F or OCF 3 , and CF 3 . Y 1 and Y 2 preferably represents Y 1 =F and Y 2 =H or Y 1 =Y 2 =F.

[0188] Particularly preferred compounds of formula XIX to formula XXVIII are the compounds of formula XXV, wherein X 0 preferably represents F, and OCF 3 .

[0189] The preferred mixture comprises at least one compound selected from S-1, S-2, S-3 and S-4,

[0190]

[0191] since these compounds are particularly useful for suppressing the smectic phase of the mixture.

[0192] The medium preferably comprises one or more neutral compounds of general formula N,

[0193]

[0194] wherein

[0195] R N1 and R N2 each independently represent an alkyl or alkoxy group having 1-15 C atoms, wherein, additionally, one or more CH 2 groups in these groups can each independently be replaced by -C≡C-, -CF 2 O-, -◇-, -◇◇-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, and wherein, additionally, one or more H atoms can be replaced by halogen,

[0196] ring A N1 , A N2 and AN3 each independently represents 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, trans-1,4-cyclohexylene, where, additionally, one or two CH 2 groups may be replaced by -O-, or 1,4-cyclohexenylene,

[0197] Z N1 and Z N2 each independently represents a single bond, -CH 2 CH 2 -, -COO-, -OCO-, -C≡C-, -CH 2 O-, -OCH 2 -, -CF 2 O-, -OCF 2 -, or -CH=CH-,

[0198] n represents 0, 1 or 2,

[0199] wherein the compound of formula N is different from the compound of formula I,

[0200] The following shows preferred compounds of formula N:

[0201]

[0202]

[0203]

[0204]

[0205] where

[0206] alkyl and alkyl* each independently represent a straight-chain alkyl having 1-9 C atoms, preferably 2-6 C atoms, and alkenyl and alkenyl* each independently represent a straight-chain alkenyl having 2-6 C atoms

[0207] 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.

[0208] - the medium additionally contains one or more compounds of formula St-1 to formula St-3,

[0209]

[0210] where R0 , Y 1 , Y 2 and X 0 has the meaning specified in claim 6. R 0 Preferably represents a straight-chain alkyl group, preferably having 1 to 6 C atoms. X 0 Preferably is F, CF 3 or OCF 3 . Y 1 Preferably represents F. Y 2 Preferably represents F. In addition, preferably where Y 1 = F and Y 2 = H compounds. The compounds of formulae St-1 to St-3 are preferably used in the mixture according to the invention at a concentration of 3 to 30% by weight, in particular 5 to 25% by weight.

[0211] - The medium additionally contains one or more pyrimidine or pyridine compounds of formulae Py-1 to Py-5,

[0212]

[0213]

[0214] where R 0 Preferably is a straight-chain alkyl group having 2 to 5 C atoms. x represents 0 or 1, preferably x = 1. The preferred mixture contains 3 to 30% by weight, in particular 5 to 20% by weight, of such pyridine (pyrimidine) compound(s).

[0215] - The medium additionally contains one or more compounds selected from the compounds of formulae Y-1, Y-2, Y-3 and Y-4,

[0216]

[0217] where

[0218] R 2A represents H, an alkyl or alkoxy group having 1 to 15 C atoms, where, additionally, one or more CH 2 groups in these groups can each independently of one another be replaced by -CH=CH-, -C≡C-, -CF 2 O-, -CH=CH-, -◇-, -◇◇-, -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 can be replaced by halogen,

[0219] L 1-4 and L 2 each independently of one another represent F, Cl, CF 3 or CHF 2, preferably each represents F,

[0220] Z 2 and Z 2’ each independently represents a single bond, -CH 2 CH 2 -, -CH=CH-, -CF 2 O-, -OCF 2 -, -CH 2 O-, -OCH 2 -, -COO-, -OCO-, -C 2 F 4 -, -CF=CF- or -CH=CHCH 2 O-,

[0221] p represents 0, 1 or 2,

[0222] q represents 0 or 1,

[0223] (O)C v H 2v+1 represents OC v H 2v+1 or C v H 2v+1 , and v represents 1 - 6.

[0224] The following shows particularly preferred compounds of formula Y - 1 to formula Y - 4:

[0225]

[0226]

[0227]

[0228]

[0229] wherein

[0230] alkyl and alkyl* each independently of one another represent a straight - chain alkyl having 1 - 6 C atoms, and

[0231] alkenyl and alkenyl* each independently of one another represent a straight - chain alkenyl having 2 - 6 C atoms.

[0232] 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.

[0233] The proportion of the compounds of formula Y - 1 to formula Y - 3 in the mixture according to the invention is preferably 0 - 30% by weight.

[0234] - The medium additionally contains one or more compounds selected from the group consisting of compounds of the formulas BC, CR, PH-1, PH-2, BF, and BS,

[0235]

[0236] wherein

[0237] 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.

[0238] The mixture according to the invention preferably contains compounds of the formulas BC, CR, PH-1, PH-2, and / or BF in an amount of 0.5 - 20% by weight, in particular 1 - 15% by weight.

[0239] Particularly preferred compounds of the formulas BC, CR, BF, and BS are compounds BC-1 to BC-7, CR-1 to CR-5, BF-1 to BF-3, and BS-1 to BS-3,

[0240]

[0241]

[0242]

[0243]

[0244] wherein

[0245] alkyl and alkyl* each independently of one another denote a straight-chain alkyl having 1 - 6 C atoms,

[0246] alkenyl and alkenyl* each independently of one another denote a straight-chain alkenyl having 2 - 6 C atoms, and

[0247] alkoxy and alkoxy* each independently of one another denote a straight-chain alkoxy having 2 - 6 C atoms.

[0248] A mixture containing one, two, or three compounds of the formula BF-3 and / or the formula BS-3 is very particularly preferred.

[0249] In the formulas given in the context,

[0250] - preferably denotes

[0251]

[0252] -R 0 Preferably a straight-chain alkyl or alkenyl group having 2 to 7 carbon atoms;

[0253] - In formula I, X 1 Preferably CF 3 , and OCF 3 ;

[0254] - The medium preferably contains one, two or three compounds of formula I;

[0255] - The medium contains CLP-n-T and / or CLP-n-OT, where n represents 2, 3, 4 or 5;

[0256] - 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;

[0257] - The medium contains CLP-V-T, CLP-nV-T or CLP-Vn-T, where n represents 1 or 2;

[0258] - The medium contains CLP-V-OT, CLP-nV-OT or CLP-Vn-OT, where n represents 1 or 2;

[0259] - The medium contains CLP-nV-m or CLP-Vn-m, where m represents 1 or 2 and n represents 1 or 2;

[0260] - 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;

[0261] - 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;

[0262] - The medium preferably contains one or more compounds of formula VI-1;

[0263] - The medium preferably contains one or more compounds of formula VI-2;

[0264] - The medium preferably contains 1 to 30% by weight, preferably 2 to 20% by weight, particularly preferably 2 to 15% by weight of the compound of formula I;

[0265] - The proportion of the compounds of formula II-XXVII in the mixture as a whole is preferably 20 to 99% by weight;

[0266] - The medium preferably contains 25 - 80% by weight, particularly preferably 30 - 70% by weight, of the compound of formula II and / or formula III;

[0267] - The medium preferably contains 0 - 70% by weight, particularly preferably 20 - 60% by weight, of the compound of formula IIa-1;

[0268] - The medium preferably contains 0 - 25% by weight, particularly preferably 5 - 25% by weight, of the compound of formula IIa-2;

[0269] - The medium preferably contains 0 - 30% by weight, particularly preferably 5 - 25% by weight, of the compound of formula IIa-3;

[0270] - The medium preferably contains 0 - 25% by weight, particularly preferably 5 - 25% by weight, of the compound of formula IIa-5;

[0271] - The medium preferably contains 5 - 40% by weight, particularly preferably 10 - 30% by weight, of the compound of formula V;

[0272] - The medium preferably contains 3 - 30% by weight, particularly preferably 6 - 25% by weight, of the compound of formula VI-1;

[0273] - The medium preferably contains 2 - 30% by weight, particularly preferably 4 - 25% by weight, of the compound of formula VI-2;

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

[0275] - The medium preferably contains 1 - 25% by weight, particularly preferably 2 - 15% by weight, of the compound of formula XIII;

[0276] - The medium preferably contains 5 - 45% by weight, particularly preferably 10 - 35% by weight, of the compound of formula XIV;

[0277] - The medium preferably contains 1 - 20% by weight, particularly preferably 2 - 15% by weight, of the compound of formula XVI;

[0278] - The medium preferably contains 5 - 30% by weight, particularly preferably 8 - 22% by weight, of the compound of formula Va, where X 0 = OCH = CF 2 ;

[0279] - The medium preferably contains the compound of formula CC-3-2V and the compound of formula CC-3-V and / or CC-3-V1;

[0280] - The medium preferably contains the compound of formula CC-3-2V and the compound of formula APUQU-2-F and / or APUQU-3-F;

[0281] - The medium preferably contains compound CC-3-2V and a compound of formula CC-3-2V1;

[0282] - The medium preferably contains compound CC-3-2V and a compound of formula PP-1-2V1;

[0283] - The medium preferably contains compound CC-3-2V and at least one compound of formula PGUQU-n-F, where n = 3, 4 or 5;

[0284] - The medium preferably contains compound CC-3-2V and at least one compound of formula DPGU-n-F, where n = 2, 3, 4 or 5.

[0285] It has been found that even a relatively small proportion of the compound of formula I mixed with a conventional liquid crystal material, but in particular with one or more compounds of formulae II to XXVIII, results in a significant reduction in the switching time parameter γ 1 / K 1 In addition, the liquid crystal medium according to the invention is characterized by its relatively high birefringence value and its light stability. At the same time, the mixture exhibits a very good VHR value after exposure to UV.

[0286] In this application, the expression "alkyl" or "alkyl*" includes straight-chain and branched alkyl groups having 1-7 C atoms, in particular the straight-chain groups methyl, ethyl, propyl, butyl, pentyl, hexyl and heptyl. Groups having 1-6 carbon atoms are generally preferred.

[0287] In this application, the expression "O-alkyl" includes straight-chain and branched alkoxy groups.

[0288] In this application, the expression "alkenyl" or "alkenyl*" includes straight-chain and branched alkenyl groups having 2-7 carbon atoms, in particular straight-chain groups. Preferred alkenyl groups are C 2 -C 7 -1E-alkenyl, C 4 -C 7 -3E-alkenyl, C 5 -C 7 -4-alkenyl, C 6 -C 7 -5-alkenyl and C 7 -6-alkenyl, in particular C 2 -C 7 -1E-alkenyl, C 4 -C 7 -3E-alkenyl and C 5 -C 7-4-enyl. 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 up to 5 carbon atoms are generally preferred.

[0289] In the present application, the expression "fluoroalkyl" includes straight-chain groups having at least one fluorine atom (preferably a 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.

[0290] In the present application, the expression "oxaalkyl" or "alkoxy" includes the formula C n H 2n+1 -O-(CH 2 ) m of straight-chain groups, where 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.

[0291] By appropriate selection of the meanings of R 1 and R 2 in formula I, 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 give lower threshold voltages and lower k 33 / k 11 values. The mixtures according to the invention are characterized in particular by high K 1 values and thus have a significantly faster response time than mixtures of the prior art.

[0292] The optimal mixing ratios of the compounds of the above-mentioned formulas mainly depend on the desired properties, the selection of the components of the above-mentioned formulas, and the selection of any other components that may be present.

[0293] Suitable mixing ratios within the ranges indicated above can be easily determined according to the specific circumstances.

[0294] The total amount of the compounds of the above-mentioned formulae in the mixture according to the invention is not critical. Thus, for the purpose of optimizing various properties, the mixture may 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 above-mentioned compounds.

[0295] In a particularly preferred embodiment, the medium according to the invention comprises compounds of formulae IV to VIII, wherein X 0 represents F, OCF 3 , OCHF 2 , OCH═CF 2 , OCF═CF 2 or OCF 2 -CF 2 H. The favorable synergistic effect with the compounds of formula I results in particularly favorable properties. In particular, mixtures comprising a compound of formula I and a compound of formula VI, or a compound of formula I and a compound of formula XI, or a compound of formula I and a compound of formula VI and a compound of formula XI are characterized by their low threshold voltage.

[0296] The individual compounds of the above-mentioned formulae and their sub-formulae that can be used in the medium according to the invention are known or can be prepared analogously to known compounds.

[0297] 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 plane-parallel outer plates (forming a panel together with the border), integrated non-linear elements on the outer plates for switching individual pixels, and a nematic liquid crystal mixture having positive dielectric anisotropy and high specific resistance located in the panel, which contains a medium of this type, and to the use of these media for electro-optical purposes.

[0298] Furthermore, the mixture according to the invention is 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 mixture according to the invention is particularly preferably suitable for TN-TFT display applications with a low operating voltage, i.e. particularly preferably for notebook applications.

[0299] The liquid crystal mixture according to the invention enables a significant broadening of the achievable 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.

[0300] The mixture according to the invention is particularly suitable for automotive applications and high-Δn TFT applications, such as PDAs, notebooks, LCD TVs and monitors.

[0301] The liquid crystal mixture according to the invention remains nematic at temperatures as low as -20 °C, preferably as low as -30 °C, particularly preferably as low as -40 °C, and has a clearing point ≥ 70 °C, preferably ≥ 74 °C, while allowing a rotational viscosity γ of ≤ 120 mPa·s, particularly preferably 60 mPa·s. 1 , enabling excellent MLC displays with fast response times to be achieved.

[0302] The dielectric anisotropy Δε of the liquid crystal mixture according to the invention is preferably ≥ +2, particularly preferably ≥ +4.

[0303] The birefringence Δn of the liquid crystal mixture according to the invention is preferably ≥ 0.08, particularly ≥ 0.10.

[0304] The nematic range of the liquid crystal mixture 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.

[0305] If the mixture according to the invention is used for IPS or FFS applications, the mixture preferably has a dielectric anisotropy value of 2 - 30 and an optical anisotropy value of 0.07 - 0.13.

[0306] It goes without saying that by appropriately selecting the components of the mixture according to the invention, higher clearing points (e.g., above 100 °C) can also be achieved at higher threshold voltages or lower clearing points at lower threshold voltages, while maintaining other favorable properties. Mixtures with higher Δε and thus low thresholds can also be obtained when the viscosity only increases slightly accordingly. The MLC displays according to the invention preferably operate 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 favorable electro - optical properties (e.g., high slope of the characteristic line and low - angle dependence of the contrast) (German Patent 30 22 818), a lower dielectric anisotropy is sufficient at the same threshold voltage as in similar displays at the second minimum. This enables significantly higher specific resistance values to be achieved when using the mixture according to the invention at the first minimum compared to the case of mixtures containing cyano compounds. 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.

[0307] The structure of the polarizer, electrode substrate, and surface-treated electrode of the MLC display according to the present invention corresponds to the usual design of this type of display. Here, the term "usual design" is broadly depicted and also includes all derivatives and improvements of the MLC display, particularly including matrix display elements based on polysilicon TFTs or MIMs.

[0308] However, a significant difference between the display according to the present 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.

[0309] The liquid crystal mixtures that can be used according to the present invention are prepared in a conventional manner per se, for example, by mixing one or more compounds of formula I with one or more compounds of formulas 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 ingredient, preferably at an elevated temperature. It is also possible to mix solutions of the components 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.

[0310] The dielectric may also include other additives known to those skilled in the art and described in the literature, such as UV stabilizers, such as 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.

[0311] To increase the anchoring force, a polymerizable compound, so-called "reactive liquid crystal", can also be additionally added to the mixture according to the present invention. Preferred polymerizable compounds are listed in Table E.

[0312] The following examples are intended to explain the present invention and not to limit it. In the context, percentage data represent weight percentages, and all temperatures are in degrees Celsius.

[0313] Throughout this application, the 1,4 - cyclohexylene ring and the 1,4 - phenylene ring are represented as follows:

[0314]

[0315] The cyclohexylene ring is a trans - 1,4 - cyclohexylene ring.

[0316] Throughout this application and the working examples, the structures of the liquid crystal compounds are indicated by abbreviations. Unless otherwise specified, they are converted to chemical formulas according to Tables 1 - 3. All groups C n H 2n+1 C m H2m+1 and C m’ H 2m’+1 or C n H 2n and C m H 2m are each a straight-chain alkyl or alkenyl group having n, m, m', or z carbon atoms, where n, m, m', and z each independently represent 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, preferably 1, 2, 3, 4, 5, or 6. The symbols for the ring units encoding the compounds in Table 1, the bridging units in Table 2, and the left- and right-hand side chains of the compounds in Table 3 are elucidated.

[0317] Table 1: Ring units

[0318]

[0319]

[0320]

[0321] Table 2: Bridging units

[0322]

[0323] Table 3: Side chains

[0324]

[0325]

[0326] Preferred mixture components are shown in Tables A and B.

[0327] Table A

[0328]

[0329]

[0330] Table B

[0331] (n = 1 - 15; (O)C n H 2n+1 refers to C n H 2n+1 or OC n H 2n+1 )

[0332]

[0333]

[0334]

[0335]

[0336]

[0337]

[0338]

[0339]

[0340]

[0341]

[0342] Particularly preferred is a liquid crystal mixture which, in addition to the compound of formula I, contains at least one, two, three, four or more compounds from Table B.

[0343] Table C illustrates the 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 dopants.

[0344] Table C

[0345]

[0346]

[0347] Table D

[0348] The following mentions stabilizers which can be added to the mixtures according to the invention, for example, in an amount of 0 - 10% by weight.

[0349]

[0350]

[0351]

[0352]

[0353]

[0354]

[0355] Table E

[0356] Table E shows example compounds that can be used in the LC medium according to the present invention, preferably as reactive liquid crystal compounds. If the mixture according to the present invention contains one or more reactive compounds, they are preferably used in an amount of 0.01 - 5 wt%. 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 wt% based on the mixture. Suitable initiators are, for example, Irgacure (BASF) or Irganox (BASF).

[0357]

[0358]

[0359]

[0360]

[0361]

[0362]

[0363]

[0364]

[0365]

[0366]

[0367]

[0368]

[0369]

[0370]

[0371] In a preferred embodiment, the mixture according to the present invention contains one or more polymerizable compounds, preferably selected from the polymerizable compounds of formula RM-1 to formula 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

[0372] The following working examples are intended to explain the present invention and not to limit it.

[0373] In the context, percentage data represents weight percentage. All temperatures are specified in degrees Celsius. m.p. represents melting point, cl.p. = clearing point. Further, C = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The data between these symbols represent the transition temperatures. Further,

[0374] V o represents the threshold voltage, capacitive [V], at 20 °C,

[0375] Δn represents the optical anisotropy measured at 20 °C and 589 nm,

[0376] Δε represents the dielectric anisotropy at 20 °C and 1 kHz,

[0377] cp. represents the clearing point [°C]

[0378] K 1 represents the elastic constant, "splay" deformation at 20 °C, [pN],

[0379] K 3 represents the elastic constant, "bend" deformation at 20 °C, [pN],

[0380] γ 1 represents the rotational viscosity at 20 °C [mPa·s], measured by the transient current method in a magnetic field

[0381] LTS represents the low temperature stability (nematic phase), measured in a glass bottle.

[0382] Mixture examples

[0383] Unless otherwise explicitly stated, the electro-optical data are measured at 20 °C in a TN panel at the first minimum (i.e., at a d·Δn value of 0.5 μm). Unless otherwise explicitly specified, the optical data are measured at 20 °C. 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 °C.

[0384] Example M1

[0385]

[0386] Example M2

[0387]

[0388] Example M3

[0389]

[0390] Example M4

[0391]

[0392] Example M5

[0393]

[0394]

[0395] Example M6

[0396]

[0397] Example M7

[0398]

[0399] Example M8

[0400]

[0401]

[0402] Example M9

[0403]

[0404] Example M10

[0405]

[0406] Example M11

[0407]

[0408] Example M12

[0409]

[0410] Example M13

[0411]

[0412] Example M14

[0413]

[0414] Example M15

[0415]

[0416]

[0417] Example M16

[0418]

[0419] Example M17

[0420]

[0421] Example M18

[0422]

[0423]

[0424] Example M19

[0425]

[0426] Example M20

[0427]

[0428] Example M21

[0429]

[0430] Example M22

[0431]

[0432]

[0433] Example M23

[0434]

[0435] Example M24

[0436]

[0437] Example M25

[0438]

[0439]

[0440] Example M26

[0441]

[0442] Example M26a

[0443] The liquid crystal mixture M26 is additionally stabilized with 300 ppm of the compound of formula ST-2

[0444] 300 ppm of ST-2

[0445] Example M27

[0446]

[0447] Example M27a

[0448] The liquid crystal mixture M27 is additionally stabilized with 300 ppm of the compound of formula ST-2

[0449] 300 ppm of ST-2

[0450] Example M28

[0451]

[0452] Example M28a

[0453] 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

[0454] 400 ppm of ST-1

[0455] and

[0456] 1000 ppm of ST-2

[0457] Example M29

[0458]

[0459]

[0460] Example M29a

[0461] 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

[0462] 400 ppm of ST-1

[0463] and

[0464] 1000 ppm of ST-2.

[0465] Example M30

[0466]

[0467] Example M30a

[0468] 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

[0469] 400 ppm of ST-1

[0470] and

[0471] 1000 ppm of ST-2.

[0472] Example M31

[0473]

[0474] Example M31a

[0475] 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

[0476] 400 ppm of ST-1

[0477] and

[0478] 1000 ppm of ST-2.

[0479] Example M32

[0480]

[0481] Example M33

[0482]

[0483] Example M34

[0484]

[0485]

[0486] Example M35

[0487]

[0488] Example M36

[0489]

[0490]

[0491] Example M37

[0492]

[0493] Example M38

[0494]

[0495] Example M39

[0496]

[0497]

[0498] Example M40

[0499]

[0500] 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:

[0501]

[0502]

[0503] 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

[0504] Example M41

[0505]

[0506] Example M42

[0507]

[0508]

[0509] Example M43

[0510]

[0511] Example M44

[0512]

[0513] Example M45

[0514]

[0515] Example M46

[0516]

[0517] Example M47

[0518]

[0519]

[0520] Example M48

[0521]

[0522] Example M49

[0523]

[0524] Example M50

[0525]

[0526]

[0527] 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:

[0528] 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

[0529] Example M51

[0530]

[0531] 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:

[0532] 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

[0533] Example M52

[0534]

[0535]

[0536] Example M53

[0537]

[0538] Example M54

[0539]

[0540] Example M55

[0541]

[0542]

[0543] The liquid crystal mixture M55 is additionally stabilized with 0.05% of the compound of formula ST-1

[0544]

[0545] Example M56

[0546]

[0547] The liquid crystal mixture M56 is additionally stabilized with 0.05% of the compound of formula ST-1

[0548]

[0549] Example M57

[0550]

[0551]

[0552] Example M58

[0553]

[0554] Example M59

[0555]

[0556] The liquid crystal mixture M59 is additionally stabilized with 0.04% of the compound of formula ST-1

[0557]

[0558] Example M60

[0559]

[0560]

[0561] The liquid crystal mixture M60 is additionally stabilized with 0.04% of the compound of formula ST-1

[0562]

[0563] Example M61

[0564]

[0565] The liquid crystal mixture M61 is additionally stabilized with 0.04% of the compound of formula ST-1

[0566]

[0567] Example M62

[0568]

[0569]

[0570] The liquid crystal mixture M62 is additionally stabilized with 0.04% of the compound of formula ST-1

[0571]

[0572] Example M63

[0573]

[0574] The liquid crystal mixture M63 is additionally stabilized with 0.04% of the compound of formula ST-1

[0575]

[0576] Example M64

[0577]

[0578]

[0579] Example M65

[0580]

[0581] Example M66

[0582]

[0583] Example M67

[0584]

[0585] Example M68

[0586]

[0587]

[0588] Example M69

[0589]

[0590] Example M70

[0591]

[0592] Example M71

[0593]

[0594]

[0595] Example M72

[0596]

[0597] Example M73

[0598]

[0599] Example M74

[0600]

[0601]

[0602] Example M75

[0603]

[0604] Example M76

[0605]

[0606] Example M77

[0607]

[0608]

[0609] Example M78

[0610]

[0611] Example M79

[0612]

[0613] Example M80

[0614]

[0615]

[0616] Example M81

[0617]

[0618] Example M82

[0619]

[0620] Example M83

[0621]

[0622]

[0623] Example M84

[0624]

[0625] Example M85

[0626]

[0627] Example M86

[0628]

[0629] Example M87

[0630]

[0631]

[0632] Example M88

[0633]

[0634] Example M89

[0635]

[0636] Example M90

[0637]

[0638]

[0639] Example M91

[0640]

[0641] Example M92

[0642]

[0643] Example M93

[0644]

[0645] Example M94

[0646]

[0647]

[0648] Example M95

[0649]

[0650] Example M96

[0651]

[0652] Example M97

[0653]

[0654] Example M98

[0655]

[0656] Example M99

[0657]

[0658] Example M100

[0659]

[0660] Example M101

[0661]

[0662]

[0663] Example M102

[0664]

[0665] Example M103

[0666]

[0667] Example M104

[0668]

[0669] Example M105

[0670]

[0671]

[0672] Example M106

[0673]

[0674] Example M107

[0675]

[0676] Example M108

[0677]

[0678]

[0679] Example M109

[0680]

[0681] Example M110

[0682]

[0683] Example M111

[0684]

[0685] Example M112

[0686]

[0687] Example M113

[0688]

[0689] Example M114

[0690]

[0691] Example M115

[0692]

[0693]

[0694] Example M116

[0695]

[0696] Example M117

[0697]

[0698] The liquid crystal mixture M117 is additionally stabilized with 0.05% of the compound of formula ST-1

[0699]

[0700] Example M118

[0701]

[0702] The liquid crystal mixture M118 is additionally stabilized with 0.05% of the compound of formula ST-1

[0703]

[0704] Example M119

[0705]

[0706] 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

[0707]

Claims

1. A liquid crystal medium having positive dielectric anisotropy, characterized in that it contains 1-30% by weight of the following compounds: - CLP-n-T and CLP-n-OT, where n represents 2, 3 or 4; - CLP-n-T, where n represents 2, 3 or 4, and CLP-V-n, where n represents 1, 2 or 3; - CLP-V-T, CLP-nV-T or CLP-Vn-T, where n represents 1 or 2; - CLP-V-OT, CLP-nV-OT or CLP-Vn-OT, where n represents 1 or 2; - CLP-nV-m or CLP-Vn-m, where m represents 1 or 2 and n represents 1 or 2; or - CLP-nV2-m, CLP-nV2-T or CLP-nV2-OT, where m represents 1 or 2 and n represents 1 or 2; wherein, 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; The liquid crystal medium additionally contains one or more compounds selected from the compounds of formula Y-1, formula Y-2, formula Y-3, formula Y-4, formula BC, formula CR, formula PH-1, formula PH-2 and formula BS, where R 2A represents H, an alkyl or alkoxy group having 1 to 15 C atoms, wherein, additionally, one or more CH 2 groups may each independently of one another be replaced by -CH=CH-, -C≡C-, -CF 2 O-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not directly linked to one another, and wherein, additionally, one or more H atoms may be replaced by halogen, L 1 and L 2 each independently represents F, Cl, CF 3 or CHF 2 , Z 2 and Z 2’ each independently represents a single bond, -CH 2 CH 2 -, -CH=CH-, -CF 2 O-, -OCF 2 -, -CH 2 O-, -OCH 2 -, -COO-, -OCO-, -C 2 F 4 -, -CF=CF- or -CH=CHCH 2 O-, p represents 0, 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; where R B1 、R B2 、R CR1 、R CR2 、R 1 and R 2 each independently has the meaning of R 2A and c represents 0, 1 or 2; wherein the liquid crystal medium additionally contains one or more compounds of formula II and / or formula III, 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, additionally, one or more CH 2 groups may each independently of one another be replaced by -C≡C-, -CF 2 O-, -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; wherein the liquid crystal medium additionally contains one or more compounds selected from the compounds of formula VI-2, formula X and / or formula XI, where R 0 represents an alkyl or alkoxy group having 1 to 15 carbon atoms, wherein one or more CH 2 groups may each independently of one another be replaced by -C≡C-, -CF 2 O-, -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, 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 1-6 each independently represents H or F, and Each independently represents 2. The liquid crystal medium according to claim 1, characterized in that the compounds of formula II and / or formula III are selected from the following compounds: wherein R 3a and R 4a each independently represent H, CH 3 、C 2 H 5 or C 3 H 7 , and "alkyl" represents a straight-chain alkyl group having 1 to 8 C atoms.

3. The liquid crystal medium according to claim 1 or 2, characterized in that it additionally contains one or more compounds selected from the compounds of formula IV to formula V and formula VII to formula VIII, where R 0 represents an alkyl or alkoxy group having 1 to 15 carbon atoms, wherein, In addition, one or more CH in these groups 2 groups may each independently of one another be replaced by -C≡C-, -CF 2 O-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly linked to one another, and wherein, in addition, one or more H atoms may be replaced by halogen, a cycloalkyl having 3 to 6 C atoms X 0 represents F, Cl, a mono-fluorinated or poly-fluorinated alkyl or alkoxy group having 1 to 6 C atoms, or 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, Z 0 represents -C 2 H 4 -,-(CH 2 ) 4 -,-CH=CH-,-CF=CF-,-C 2 F 4 -,-CH 2 CF 2 -,-CF 2 CH 2 -,-CH 2 O-,-OCH 2 -,- COO−, −CF 2 O− or −OCF 2 −, which also represents a single bond in Formulas V and VI, and r represents 0 or 1.

4. The liquid crystal medium according to claim 1 or 2, characterized in that it additionally contains one or more compounds selected from the compounds of formula Va to formula Vj, wherein R 0 and X 0 have the meanings specified in claim 3.

5. The liquid crystal medium according to claim 1 or 2, characterized in that it additionally contains one or more compounds selected from the compounds of formula VI-1a to formula VI-1d, wherein R 0 and X 0 have the meanings specified in claim 3.

6. The liquid crystal medium according to claim 1 or 2, characterized in that the compound of formula VI-2 is selected from one or more compounds of formula VI-2a to formula VI-2f, wherein R 0 and X 0 have the meanings specified in claim 3.

7. The liquid crystal medium according to claim 1 or 2, 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 C atoms, and Y 1 represents H or F.

8. The liquid crystal medium according to claim 1 or 2, characterized in that it additionally contains one or more compounds selected from the compounds of formula XIII to formula XVI, wherein R 0 , X 0 , Y 1 and Y 2 have the meanings specified in claim 3.

9. The liquid crystal medium according to claim 1 or 2, characterized in that the compound of formula II is selected from the following compounds:

10. The liquid crystal medium according to claim 1 or 2, characterized in that it additionally contains one or more compounds selected from the compounds of formula D1, formula D2, formula D3, formula D4 and formula D5, where Y 1 、Y 2 、R 0 and X 0 have the meanings specified in claim 3.

11. The liquid crystal medium according to claim 1 or 2, characterized in that it additionally contains one or more UV stabilizers and / or antioxidants.

12. The liquid crystal medium according to claim 1 or 2, characterized in that it additionally contains one or more polymerizable compounds.

13. A method for preparing a liquid crystal medium according to any one of claims 1 - 12, 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.

14. Use of the liquid crystal medium according to any one of claims 1 - 12 for electro - optical purposes.

15. Use of the liquid crystal medium according to claim 14 in 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.

16. An electro - optical liquid crystal display containing the liquid crystal medium according to any one of claims 1 - 12.

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