WO2019076899A1

WO2019076899A1 - Liquid-crystalline medium and liquid-crystal display comprising the same

Info

Publication number: WO2019076899A1
Application number: PCT/EP2018/078252
Authority: WO
Inventors: Atsutaka Manabe; Constanze Brocke
Original assignee: Merck Patent Gmbh
Priority date: 2017-10-18
Filing date: 2018-10-16
Publication date: 2019-04-25
Also published as: EP3697868A1; CN111315847A; TW201928024A

Abstract

The invention relates to a liquid-crystalline medium having a nematic phase comprising one or more compounds of formula (B) wherein the parameters have the meaning given in the text, to the use thereof in an electro-optical display,particularly in an active-matrix display based on the IPS or FFS effect,to displays of this type which contain a liquid-crystalline medium of this type and to the use of the compounds of formula B for improvement of the transmission and/or response times of a liquid-crystalline medium which comprises one or more additional mesogenic compounds.

Description

 Liquid-crystalline medium and liquid-crystal display comprising the same

The present invention relates to novel liquid crystalline media, in particular for use in liquid-crystal displays, and to these liquid-crystal displays, particularly to liquid-crystal displays which use the IPS (in-Djane switching) or, preferably, the FFS (fringe field switching) effect using dielectncally positive liquid crystals. The last one is also called SG-FFS (super grip FFS) effect occasionally. For this effect dielectncally positive liquid crystals are used, which comprise one or more compounds having at the same time a high dielectric constant parallel to the molecular director and perpendicular to the molecular director, leading to a large average dielectric constant and a high dielectric ratio. The liquid crystalline media optionally additionally comprise dielectncally negative, dielectncally neutral compounds or both. The liquid crystalline media are used in a

homogeneous (i.e. planar) initial alignment. The liquid-crystal media according to the invention have a positive dielectric anisotropy and comprise compounds having at the same time large dielectric constants parallel and perpendicular to the molecular director.

The media are distinguished by a particularly high transmission and reduced response time in respective displays, which is brought about by their unique combination of physical properties, especially by their dielectric properties and in particular by their high ratio of (ε± / s_av.) respectively of the high values of their dielectric ratio (ε± / Δε). This also leads to their excellent performance in the displays according to the invention.

IPS and FFS displays using dielectncally positive liquid crystals are well known in the field and have been widely adopted for various types of displays like e.g. desk top monitors and TV sets, but also for mobile applications.

However, recently, IPS and in particular FFS displays using dielectncally negative liquid crystals are widely adopted. The latter ones are sometimes also called or UB-FFS (ultra bright FFS). Such displays are disclosed e.g. in US 2013/0207038 A1 . These displays are characterized by a markedly increased transmission compared to the previously used IPS- and FFS displays, which have been dielectrically positive liquid crystals. These displays using conventional, dielectrically negative liquid crystals, however, have the severe disadvantage of requiring a higher operation voltage than the respective displays using dielectrically positive liquid crystals. Liquid crystalline media used for UB-FFS have a dielectric anisotropy of -0.5 or less and preferably of -1 .5 or less. Liquid crystalline media used for HB-FFS (high brightness FFS) have a dielectric anisotropy of 0.5 or more and preferably of 1 .5 or more. Liquid crystalline media used for HB-FFS comprising both dielectrically negative and dielectrically positive liquid crystalline compounds, respectively mesogenic compounds are disclosed e.g. in US 2013/0207038 A1 . These media feature rather large values of ε± and of s_av. already, however, their ratio of (ε± / Δε) is relatively small.

According to the present application, however, the IPS or the FFS effect with dielectrically positive liquid crystalline media in a homogeneous alignment are preferred.

Industrial application of this effect in electro-optical display elements requires LC phases which have to meet a multiplicity of requirements. Particularly important here are chemical resistance to moisture, air and physi- cal influences, such as heat, radiation in the infrared, visible and ultraviolet regions, and direct (DC) and alternating (AC) electric fields.

Furthermore, LC phases which can be used industrially are required to have a liquid-crystalline mesophase in a suitable temperature range and low viscosity.

None of the series of compounds having a liquid-crystalline mesophase that have been disclosed hitherto includes a single compound which meets all these requirements. Mixtures of two to 25, preferably three to 18, compounds are therefore generally prepared in order to obtain substances which can be used as LC phases. Matrix liquid-crystal displays (MLC displays) are known. Non-linear elements which can be used for individual switching of the individual pixels are, for example, active elements (i.e. transistors). The term "active matrix" is then used, where in general use is made of thin-film transistors (TFTs), which are generally arranged on a glass plate as substrate.

A distinction is made between two technologies: TFTs comprising compound semiconductors, such as, for example, CdSe, or metal oxides like ZnO or TFTs based on polycrystalline and, inter alia, amorphous silicon. The latter technology currently has the greatest commercial importance worldwide.

The TFT matrix is applied to the inside of one glass plate of the display, while the other glass plate carries the transparent counter electrode on its inside. Compared with the size of the pixel electrode, the TFT is very small and has virtually no adverse effect on the image. This technology can also be extended to fully colour-capable displays, in which a mosaic of red, green and blue filters is arranged in such a way that a filter element is located opposite each switchable pixel.

The TFT displays most used hitherto usually operate with crossed polaris- ers in transmission and are backlit. For TV applications, ECB (or VAN) cells or FFS cells are used, whereas monitors usually use IPS cells or TN (twisted nematic) cells, and notebooks, laptops and mobile applications usually use TN, VA or FFS cells.

The term MLC displays here encompasses any matrix display having integrated non-linear elements, i.e., besides the active matrix, also displays with passive elements, such as varistors or diodes (MIM = metal-insulator- metal).

MLC displays of this type are particularly suitable for TV applications, monitors and notebooks or for displays with a high information density, for example in automobile manufacture or aircraft construction. Besides problems regarding the angle dependence of the contrast and the response times, difficulties also arise in MLC displays due to insufficiently high specific resistance of the liquid-crystal mixtures [TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K., TAJIMA, E., WATA- NABE, H., SHIMIZU, H., Proc. Eurodisplay 84, Sept. 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, pp. 141 ff., Paris; STROMER, M., Proc. Eurodisplay 84, Sept. 1984: Design of Thin Film Transistors for Matrix Addressing of Television Liquid Crystal Displays, pp. 145 ff., Paris]. With decreasing resistance, the contrast of an MLC display deteriorates. Since the specific resistance of the liquid-crystal mixture gen- erally drops over the life of an MLC display owing to interaction with the inside surfaces of the display, a high (initial) resistance is very important for displays that have to have acceptable resistance values over a long operating period. Displays which use the ECB effect have become established as so-called VAN (vertically aligned nematic) displays, besides IPS displays (for example: Yeo, S.D., Paper 15.3: "An LC Display for the TV Application", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp. 758 and 759) and the long-known TN displays, as one of the three more recent types of liquid-crystal display that are currently the most important, in particular for television applications.

The most important designs may be mentioned here: MVA (multi-domain vertical alignment, for example: Yoshide, H. et al., Paper 3.1 : "MVA LCD for Notebook or Mobile PCs SID 2004 International Symposium,

Digest of Technical Papers, XXXV, Book I, pp. 6 to 9, and Liu, C.T. et al., Paper 15.1 : "A 46-inch TFT-LCD HDTV Technology SID 2004

International Symposium, Digest of Technical Papers, XXXV, Book II, pp. 750 to 753), PVA (patterned vertical alignment, for example: Kim, Sang Soo, Paper 15.4: "Super PVA Sets New State-of-the-Art for LCD-TV", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp. 760 to 763) and ASV (advanced super view, for example: Shigeta, Mitzuhiro and Fukuoka, Hirofumi, Paper 15.2: "Development of High Quality LCDTV", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp. 754 to 757). More modern versions of the VA effect, are the so called PAVA (photo-alignment VA) and PSVA (polymer- stabilized VA).

In general form, the technologies are compared, for example, in Souk, Jun, SID Seminar 2004, Seminar M-6: "Recent Advances in LCD

Technology", Seminar Lecture Notes, M-6/1 to M-6/26, and Miller, Ian, SID Seminar 2004, Seminar M-7: "LCD-Television", Seminar Lecture Notes, M-7/1 to M-7/32. Although the response times of modern ECB displays have already been significantly improved by addressing methods with overdrive, for example: Kim, Hyeon Kyeong et al., Paper 9.1 : "A 57-in. Wide UXGA TFT-LCD for HDTV Application", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book I, pp. 106 to 109, the achievement of video-compatible response times, in particular in the switching of grey shades, is still a problem which has not yet been solved to a satisfactory extent.

ECB displays, like ASV displays, use liquid-crystalline media having negative dielectric anisotropy (Δε), whereas TN and to date all conventional IPS displays use liquid-crystalline media having positive dielectric anisotropy. However, presently there is an increasing demand for IPS and FFS displays utilizing dielectrically negative liquid crystalline media.

In liquid-crystal displays of this type, the liquid crystals are used as dielectrics, whose optical properties change reversibly on application of an elec- trical voltage.

Since in displays in general, i.e. also in displays in accordance with these mentioned effects, the operating voltage should be as low as possible, use is made of liquid-crystal media which are generally predominantly com- posed of liquid-crystal compounds, all of which have the same sign of the dielectric anisotropy and have the highest possible value of the dielectric anisotropy. In general, at most relatively small proportions of neutral compounds and if possible no compounds having a sign of the dielectric anisotropy which is opposite to that of the medium are employed. In the case of liquid-crystal media having negative dielectric anisotropy e.g. for ECB or UB-FFS displays, predominantly compounds having negative dielectric anisotropy are thus employed. The respective liquid-crystalline media employed generally consist predominantly and usually even essentially of liquid-crystal compounds having negative dielectric anisotropy.

In the media used in accordance with the present application, significant amounts of dielectncally positive liquid-crystal compounds and generally only very small amounts of dielectncally compounds or even none at all are typically employed, since in general the liquid-crystal displays are intended to have the lowest possible addressing voltages. At the same time small amounts of dielectncally neutral compounds may be beneficially used in some cases.

US 2013/0207038 A1 discloses liquid crystalline media for HB-FFS displays proposing to improve the performance of the FFS displays using liquid crystals having a positive dielectric anisotropy by the additional incorporation of dielectncally negative liquid crystals. This, however, leads to the necessity of a compensation of the negative contribution of these compounds to the overall dielectric anisotropy of the resultant media. To this end, either the concentration of the dielectncally positive materials has to be increased, which, in turn, leaves less room for the use of

dielectncally neutral compounds as diluters in the mixtures, or,

alternatively, compounds with a stronger positive dielectric anisotropy have to be used. Both of these alternatives have the strong drawback of increasing the response time of the liquid crystals in the displays. Liquid crystalline media having a positive dielectric anisotropy for IPS and FFS displays have already been disclosed. In the following some examples will be given.

CN 104232105 A, WO 2014/192390 and WO 2015/007131 disclose liquid crystalline media with a positive dielectric anisotropy, some of which have a rather high dielectric constant perpendicular to the director.

Obviously, the phase range of the liquid-crystal mixture must be sufficiently broad for the intended application of the display. The response times of the liquid-crystal media in the displays also have to be improved, i.e. reduced. This is particularly important for displays for television or multimedia applications. In order to improve the response times, it has repeatedly been proposed in the past to optimise the rota- tional viscosity of the liquid-crystal media (γι), i.e. to achieve media having the lowest possible rotational viscosity. However, the results achieved here are inadequate for many applications and therefore make it appear desirable to find further optimisation approaches. US 2016-0298033 (A) discloses, amongst others, the following

compounds

for use in LCDs, whereas US 2016-0298034 (A) discloses, amongst others, compounds of the following formulae

and proposes the respective compounds for the same use.

Adequate stability of the media to extreme loads, in particular to UV exposure and heating, is very particularly important. In particular in the case of applications in displays in mobile equipment, such as, for example, mobile telephones, this may be crucial.

Besides their relatively poor transmission and their relatively long response times, the MLC displays disclosed hitherto, they have further disadvantages. These are e.g. their comparatively low contrast, their relatively high viewing-angle dependence and the difficulty in the reproduction of grey scales in these displays, especially when observed from an oblique viewing angle, as well as their inadequate VHR and their inadequate lifetime. The desired improvements of the transmission of the displays and of their response times are required in order to improve their energy efficiency, respectively their capacity to render rapidly moving pictures. There thus continues to be a great demand for MLC displays having very high specific resistance at the same time as a large working-temperature range, short response times and a low threshold voltage, with the aid of which various grey shades can be produced and which have, in particular, a good and stable VHR.

The invention has the object of providing MLC displays, not only for monitor and TV applications, but also for mobile applications such as e.g.

telephones and navigation systems, which are based on the ECB, IPS or FFS effect, do not have the disadvantages indicated above, or only do so to a lesser extent, and at the same time have very high specific resistance values. In particular, it must be ensured for mobile telephones and navigation systems that they also work at extremely high and extremely low temperatures. Surprisingly, it has been found that it is possible to achieve liquid-crystal displays which have, in particular in IPS and FFS displays, a low threshold voltage with short response times, a sufficiently broad nematic phase, favourable birefringence (Δη) and, at the same time, a high transmission, good stability to decomposition by heating and by UV exposure, and a stable, high VHR if use is made in these display elements of nematic liquid-crystal mixtures which comprise at least one compound, preferably two or more compounds of formula B, preferably selected from the group of the compounds of the sub-formulae B-1 and B-2, particularly preferably the sub-formula B-1 and/or B-2, more preferably both of formula B-1 and of formula B-2, and preferably additionally one or more compounds of formula I, preferably selected from the group of the compounds of the sub- formulae 1-1 and I-2, particularly preferably the sub-formula 1-1 and/or I-2, most preferably of formula I-2 and most preferably both of formula 1-1 and of formula I-2, and preferably additionally at least one compound, preferably two or more compounds, selected from the group of the compounds of the formulae II and III, the former preferably of formula 11-1 and/or II-2, and/or at least one compound, preferably two or more compounds selected from the group of formulae IV and/or V and, preferably, one or more compounds selected from the group of formulae VII to IX (all formulae as defined herein below).

Media of this type can be used, in particular, for electro-optical displays having active-matrix addressing for IPS - or FFS displays.

The invention thus relates to a liquid-crystalline medium on a mixture of polar compounds comprising one or more compounds having

a dielectric ratio of the dielectric constant perpendicular to the director to the dielectric anisotropy (ε± / Δε) of 2.0 or less and a high dielectric constant perpendicular to the director (ε±) preferably of 3.8 or more, preferably of 4.5 or more, and, most preferably of 6.0 or more.

The ratio of the dielectric constant perpendicular to the director to the dielectric anisotropy (ε± / Δε) of 1 .0 or more corresponds to the ratio of the dielectric constant parallel (ε ) to the director to dielectric constant perpendicular (ε±) to the director, i.e. to the ratio of (ε / ε± ) of 2.0 or less.

The media according to the present invention preferably additionally comprise a one or more compounds selected from the group of compounds of formulae II and III, preferably one or more compounds of formula II, more preferably in addition one or more compounds of formula III and, most preferably, additionally one or more compounds selected from the group of the compounds of formulae IV and V and, again preferably, one or more compounds selected from the group of compounds of formulae VI to IX (all formulae as defined below). The mixtures according to the invention exhibit very broad nematic phase ranges with clearing points > 70°C, very favourable values for the capaci- tive threshold, relatively high values for the holding ratio and at the same time good low-temperature stabilities at -20°C and -30°C, as well as very low rotational viscosities. The mixtures according to the invention are fur- thermore distinguished by a good ratio of clearing point and rotational viscosity and by a relatively high positive dielectric anisotropy. Now, it has been found surprisingly that LCs of the FFS type using liquid crystals with positive dielectric anisotropy may be realised using specially selected liquid crystalline media. These media are characterised by a particular combination of physical properties. Most decisive amongst these are their dielectric properties and here a high average dielectric constant (ε_av ), a high dielectric constant perpendicular to the director of the liquid crystal molecules (ε±) and, in particular, the relatively high ratio of these latter two values: (ε± / Δε).

Preferably the liquid-crystalline media according to the present invention, on the one hand, have a value of the dielectric anisotropy of 1 .5 or more, preferably of 3.5 or more preferably of 4.5 or more. At the other hand, they preferably have a dielectric anisotropy of 26 or less.

Preferably the liquid-crystalline media according to the present invention, on the one hand, have a value of the dielectric constant perpendicular to the director of 2 or more, more preferably of 6 or more and, on the other hand preferably of 20 or less.

Preferably the liquid crystalline media according to the present invention preferably have a dielectric ratio (ε± / Δε) of 2.0 or less, more preferably of 1 .5 or less and, most preferably, of 1 .0 or less.

The liquid crystalline media according to the present invention in a preferred embodiment have a positive dielectric anisotropy, preferably in the range from 1 .5 or more to 20.0 or less, more preferably in the range from 3.0 or more to 8.0 or less and, most preferably in the range from 4.0 or more to 7.0. or less.

The liquid crystalline media according to the present invention in a preferred embodiment, which may be the same as the preferred embodiment mentioned above, have a dielectric constant perpendicular to the director of the liquid crystal molecules (ε±) of 5.0 or more, more preferably of 6.0 or more, more preferably of 7.0 or more, more preferably of 8.0 or more, more preferably of 9 or more and, most preferably, of 10.0 or more.

The liquid crystalline medium of the present invention has a dielectric anisotropy of 0.5 or more preferably of 1 .5 or more and a dielectric ratio (ε± / Δε) of 2.0 or less and comprises a) one or more compounds of formula B, preferably selected from the group of compounds of formulae B-1 and B-2, preferably in a concentration in the range from 1 % to 60 %, more preferably in the range from 5 % to 40 %, particularly preferably in the range from 8 % to 35 %,

another,

preferably

denotes 1 or 2, preferably 1 , denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyi or fluorinated alkenyl having 2 to 7 C atoms, preferably alkyl, alkoxy, alkenyl or alkenyloxy, more preferably alkyl, alkenyl, alkoxy or alkenyloxy, and, most preferably alkyl, and denotes F, CI, fluorinated alkyl, fluorinated alkenyl, fluorinated alkoxy or fluorinated alkenlyoxy, the latter four groups preferably having 1 to 4 C atoms, more preferably F, CI, CF3 or OCF3, and one or more dielectrically positive compounds selected from the group of compounds of formulae II and III, preferably of compounds having a dielectric anisotropy of greater than 3 each:

denotes alkyi, alkoxy, fluorinated alkyi or fluonnated

alkoxy having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyi or fluorinated alkenyl having 2 to 7 C atoms and preferably alkyi or alkenyl,

on each appearance, independently of one another, denote

L²¹ and L²² denote H or F, preferably L²¹ denotes F,

X² denotes halogen, halogenated alkyl or alkoxy having 1 to 3 C atoms or halogenated alkenyl or alkenyloxy having 2 or 3 C atoms, preferably F, CI, -OCF₃, -O-CH₂CF₃, -O-CH=CH₂, -O-CH=CF₂ or -CF₃, very preferably F, CI, -O-CH=CF₂ or -OCF₃, m denotes 0, 1 , 2 or 3, preferably 1 or 2 and particularly preferably 1 , R³ denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyi or fluorinated alkenyl having 2 to 7 C atoms and preferably alkyl or alkenyl,

on each a earance, independently of one another, are

independently of one another, denote H or F, preferably L³¹ denotes F, denotes halogen, halogenated alkyl or alkoxy having 1 to 3 C atoms or halogenated alkenyl or alkenyloxy having 2 or 3 C atoms, F, CI, -OCF₃, -OCHF₂,

-O-CH2CF3, -O-CH=CF₂, -O-CH=CH₂ or -CF₃, very preferably F, CI, -O-CH=CF₂, -OCHF2 or -OCF3, denotes -CH2CH2-, -CF2CF2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CH2O- or a single bond,

preferably -CH2CH2-, -COO-, trans -CH=CH- or a single

bond and very preferably -COO-, trans-CH=CH- or a single bond, and denotes 0, 1 , 2 or 3, preferably 1 ,2 or 3 and particularly preferably 1 , and optionally one or more dielectrically neutral compounds selected from the group of formulae IV and V:

in which R⁴¹ and R⁴², independently of one another, have the meaning indicated above for R² under formula II, preferably R⁴¹ denotes alkyl and R⁴² denotes alkyl or alkoxy or R⁴¹ denotes alkenyl and R⁴² denotes alkyl,

independently of one another and, if

. 41

— occurs twice, also these independently of one another, denote

preferably one or more of

denotes or denote,

Z⁴¹ and Z⁴², independently of one another and, if Z⁴¹ occurs twice, also these independently of one another,

denote -CH₂CH₂-, -COO-, trans-CH=CH-, trans- CF=CF-, -CH2O-, -CF2O-, -C≡C- or a single bond, preferably one or more thereof denotes/denote a single bond, and P denotes 0, 1 or 2, preferably 0 or 1 , and

R⁵¹ and R⁵², independently of one another, have one of the meanings given for R⁴¹ and R⁴² and preferably denote alkyl having 1 to 7 C atoms, preferably n-alkyl, particularly preferably n- alkyl having 1 to 5 C atoms, alkoxy having 1 to 7 C atoms, preferably n-alkoxy, particularly preferably n-alkoxy having 2 to 5 C atoms, alkoxyalkyi, alkenyl or alkenyloxy having 2 to 7 C atoms, preferably having 2 to 4 C atoms, preferably alkenyloxy,

if resent each inde endentl of one another, denote

preferably

preferably

denotes and, if present,

preferably denotes

Z⁵¹ to Z⁵³ each, independently of one another, denote -CH2-CH2-

, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, preferably -CH2-CH2-, -CH2-O- or a single bond and particu- larly preferably a single bond, i and j each, independently of one another, denote 0 or 1 ,

(i + j) preferably denotes 0, 1 or 2, more preferably 0 or 1 and, most preferably, 1 . again optionally, either alternatively or additionally, one or more dielectrically negative compounds selected from the group of formulae VI to IX:

denotes an unsubstituted alkyl radical having 1 to 7 C atoms, preferably a straight-chain alkyl radical, more preferably an n-alkyl radical, most preferably propyl or pentyl, an unsubstituted alkenyl radical having 2 to 7 C atoms, preferably a straight-chain alkenyl radical, particularly preferably having 2 to 5 C atoms, an unsubstituted alkoxy radical having 1 to 6 C atoms or an unsubstituted alkenyloxy radical having 2 to 6 C atoms, denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkoxy radical having 1 to 6 C atoms or an unsubstituted alkenyloxy radical having 2 to 6 C atoms, and denotes 0 or 1 , denotes an unsubstituted alkyl radical having 1 to 7 C atoms, preferably a straight-chain alkyl radical, more preferably an n-alkyl radical, most preferably propyl or pentyl, or an unsubstituted alkenyl radical having 2 to 7 C atoms, preferably a straight-chain alkenyl radical, particularly preferably having 2 to 5 C atoms, denotes an unsubstituted alkyl radical having 1 to 7 C atoms, preferably having 2 to 5 C atoms, an unsubstituted alkoxy radical having 1 to 6 C atoms, preferably having 1 , 2, 3 or 4 C atoms, or an unsubstituted alkenyloxy radical having 2 to 6 C atoms, preferably having 2, 3 or 4 C atoms, and

denotes an unsubstituted alkyl radical having 1 to 7 C atoms, preferably a straight-chain alkyl radical, more preferably an n-alkyl radical, most preferably propyl or pentyl, or an unsubstituted alkenyl radical having 2 to 7 C atoms, preferably a straight-chain alkenyl radical, particularly preferably having 2 to 5 C atoms, denotes an unsubstituted alkyl radical having 1 to 7 C atoms, preferably having 2 to 5 C atoms, an unsubstituted alkoxy radical having 1 to 6 C atoms, preferably having 1 ,

2, 3 or 4 C atoms, or an unsubstituted alkenyloxy radical having 2 to 6 C atoms, preferably having 2, 3 or 4 C atoms,

preferably

more preferably

Z⁸ denotes -(C=O)-O-, -CH2-O-, -CF2-O- or -CH2-CH2-, preferably

-(C=O)-O- or -CH2-O-, and o denotes 0 or 1 ,

R⁹¹ and R⁹² independently of one another have the meaning given for R⁷² above,

R⁹¹ preferably denotes an alkyl radical having 2 to 5 C atoms, preferably having 3 to 5 C atoms,

_R92 preferably denotes an alkyl or alkoxy radical having 2 to 5 C atoms, more preferably an alkoxy radical having 2 to 4 C atoms, or an alkenyloxy radical having 2 to 4 C atoms.

p and q independently of each other denote 0 or 1 , and (p + q) preferably denotes 0 or 1 , in case

alternatively, preferably p = q = 1 d) again optionally, either alternatively or additionally,

compounds of formula I:

denotes 0 or 1 , independently of each other denote alkyi, alkoxy, fluorinated alkyi or fluorinated alkoxy, preferably having

1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl or

fluorinated alkenyl having 2 to 7 C atoms and preferably alkyi, alkoxy, alkenyl or alkenyloxy, most preferably alkyl, alkoxy or alkenyloxy, and R¹¹ alternatively

denotes R¹ and R¹² alternatively denotes X¹,

R¹ denotes alkyl, alkoxy, fluorinated alkyl or fluorinated

alkoxy, preferably having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl, preferably having 2 to 7 C atoms and preferably alkyl or alkenyl, and

X¹ denotes F, CI, fluorinated alkyl, fluorinated alkenyl,

fluorinated alkoxy or fluorinated alkenyoxy, the latter four groups preferably having 1 to 4 C atoms, more preferably F, CI, CF₃ or OCF₃, from which the compounds of formula B are excluded.

The liquid-crystalline media in accordance with the present application preferably have a nematic phase. Throughout this application and especially for the definition of R¹ alkyl means an alkyl group, which may be straight-chain or branched. Each of these radicals is preferably straight-chain and preferably has 1 , 2, 3, 4, 5, 6, 7 or 8 C atoms and is accordingly preferably methyl, ethyl, n-propyl, n- butyl, n-pentyl, n-hexyl or n-heptyl.

In case alkyl means a branched alkyl group it preferably means 2-alkyl, 2- methylalkyl or 2-(2-ethyl)-alkyl, preferably 2-butyl (=1 -methylpropyl), 2- methylbutyl, 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2-propylpentyl, in particular 2-methylbutyl, 2-methylbutoxy 4-methylhexyl, 2-hexyl, 2-octyl, 2-nonyl, 2-decyl and 2-dodecyl. Most preferred of these groups are 2- hexyl and 2-octyl.

Respective branched groups, especially for R¹, which lead to chiral compounds are also called chiral groups in this application. Particularly preferred chiral groups are 2-alkyl, 2-alkoxy, 2-methylalkyl, 2-methylalkoxy, 2- fluoroalkyi, 2-fluoroalkoxy, 2-(2-ethin)-alkyl, 2-(2-ethin)-alkoxy, 1 ,1 ,1 -trifluoro-2- alkyl and 1 ,1 ,1 -trifluoro-2-alkoxy.

Particularly preferred chiral groups are 2-butyl (=1 -methylpropyl), 2- methylbutyl, 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2-propylpentyl, in particular 2-methylbutyl, 2-methylbutoxy, 2-methylpentoxy, 3- methylpentoxy, 2-ethylhexoxy, 1 -methylhexoxy, 2-octyloxy, 2-oxa-3- methylbutyl, 3-oxa-4-methylpentyl, 4-methylhexyl, 2-hexyl, 2-octyl, 2-nonyl 2-decyl, 2-dodecyl, 6-methoxyoctoxy, 6-methyloctoxy, 6- methyloctanoyloxy, 5-methylheptyloxycarbonyl, 2-methylbutyryloxy, 3- methylvaleroyloxy, 4-methylhexanoyloxy, 2-chlorpropionyloxy, 2-chloro-3- methylbutyryloxy, 2-chloro-4-methylvaleryloxy, 2-chloro-3- methylvaleryloxy, 2-methyl-3-oxapentyl, 2-methyl-3-oxahexyl, 1 - methoxypropyl-2-oxy, 1 -ethoxypropyl-2-oxy, 1 -propoxypropyl-2-oxy, 1 - butoxypropyl-2-oxy, 2-fluorooctyloxy, 2-fluorodecyloxy, 1 ,1 ,1 -trifluoro-2- octyloxy, 1 ,1 ,1 -trifluoro-2-octyl, 2-fluoromethyloctyloxy for example. Very preferred are 2-hexyl, 2-octyl, 2-octyloxy, 1 ,1 ,1 -trifluoro-2-hexyl, 1 ,1 ,1 - trifluoro-2-octyl and 1 ,1 ,1 -trifluoro-2-octyloxy.

Preferably the compounds of formula B are selected from the group of compounds of formulae B-1 and B-2:

in which denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyi or fluorinated alkenyl having 2 to 7 C atoms and preferably alkyl or alkenyl, and denotes F, CI, CN, NCS, fluorinated alkyl, fluorinated alkenyl, fluorinated alkoxy or fluorinated alkenlyoxy, the latter four groups preferably having 1 to 4 C atoms, preferably F, CI, CF3 or OCF3, more preferably F, CF3, or OCF3 and, most preferably, OCF3 or CF3. Preferably the compounds of formula I are selected from the group of compounds of formulae 1-1 and I-2:

in which independently of each other denote alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyi or fluorinated alkenyl having 2 to 7 C atoms and preferably alkyl, alkoxy, alkenyl or alkenyloxy, most preferably alkoxy or alkenyloxy, denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyi or fluorinated alkenyl having 2 to 7 C atoms and preferably alkyl or alkenyl, and X¹ denotes F, CI, CN, NCS, fluohnated alkyl, fluorinated alkenyl, fluorinated alkoxy or fluorinated alkenlyoxy, the latter four groups preferably having 1 to 4 C atoms, preferably F, CI, CF3 or OCF3, more preferably F, CF3 or OCF3 and, most preferably, CF3 or OCF3.

The compounds of formula B are prepared according to the following scheme (Scheme 1 ).

B-1 wherein the parameters have the respective meanings given under formula B above.

The stereomers of B-1 , if any, are separated by usual means, such as flash chromatography and or re-recystallization, either with or without use of seed crystals, which may be applied as single, sole steps or repeatedly and/or in combination with each other. The process and the subsequent work-up of the reaction mixture can basically be carried out as batch reaction or in a continuous reaction manner. The continuous reaction manner comprises, for example, the reaction in a continuous stirred-tank reactor, a stirred-reactor cascade, a loop or cross-flow reactor, a flow tube or in a micro-reactor. The reaction mixtures are optionally worked up, as required, by filtration via solid phases, chromatography, separation between immiscible phases (for example extraction), adsorption on solid supports, distilling-off of solvents and/or azeotropic mixtures, selective distillation, sublimation, crystallization, co-crystallization or by nanofiltration on membranes.

The compounds of formula I are prepared according to WO 02/055463 and compounds of the formula 1-1 , containing two alkoxy groups (R¹¹ =>

R¹-O; R¹² => R²-O) are preferably prepared starting from the basic compound dibenzofuran according to the following scheme: (Scheme 2).

- Continuation of Scheme 2 -

- Continuation of Scheme 2 -

Scheme 2. Synthesis of the compounds of the formula 1-1 with two alkoxy end groups

The compounds of formula 1-1 containing one alkoxy group (R¹-O)and one alkyl group (R²), (R¹¹ => R¹-O; R¹² => R²) are preferably prepared starting from the basic compound dibenzofuran according to the following scheme: (Scheme 3).

Scheme 3. Synthesis of the compounds of the formula 1-1 with one alkyl and one alkoy end group. The radical R corresponds to a radical such as R² correspondingly shortened by one carbon atom.

The compounds of formula 1-1 , containing two alkyl groups (R¹¹ => R¹; R¹² => R²), are preferably prepared starting from the basic compound dibenzo- furan according to the following scheme: (Scheme 4).

Scheme 4. Synthesis of the compounds of the formula 1-1 . The radical R of the aldehyde employed corresponds to a radical such as R² correspondingly shortened by one carbon atom.

The compounds of formula I-2 are preferably prepared e.g. according to the following scheme.

The invention furthermore relates to the use of liquid-crystal mixtures and liquid-crystalline media according to the invention in IPS and FFS displays, in particular the use in SG-FFS displays containing a liquid-crystalline medium, for improving the response times and/or the transmission.

The invention furthermore relates to a liquid-crystal display containing a liquid-crystalline medium according to the invention, in particular an IPS or FFS display, particularly preferably a FFS or SG-FFS display.

The invention furthermore relates to a liquid-crystal display of the IPS or FFS type comprising a liquid-crystal cell consisting of two substrates, where at least one substrate is transparent to light and at least one substrate has an electrode layer, and a layer, located between the substrates, of a liquid-crystalline medium comprising a polymerised component and a low-molecular-weight component, where the polymerised component is obtainable by polymerisation of one or more polymerisable compounds in the liquid-crystalline medium between the substrates of the liquid-crystal cell, preferably with application of an electrical voltage and where the low- molecular-weight component is a liquid-crystal mixture according to the invention as described above and below.

The displays in accordance with the present invention are preferably addressed by an active matrix (active matrix LCDs, AMDs for short), preferably by a matrix of thin-film transistors (TFTs). However, the liquid crystals according to the invention can also be used in an advantageous manner in displays having other known addressing means. The invention furthermore relates to a process for the preparation of a liquid-crystalline medium according to the invention by mixing one or more compounds of formula B, preferably selected from the group of

compounds of formulae B-1 and B-2, with one or more low-molecular- weight liquid-crystalline compounds, or a liquid-crystal mixture and optionally with further liquid-crystalline compounds and/or additives.

The following meanings apply above and below:

The term "FFS" is, unless indicated otherwise, used to represent FFS and SG-FFS displays.

The term "mesogenic group" is known to the person skilled in the art and is described in the literature, and denotes a group which, due to the ani- sotropy of its attracting and repelling interactions, essentially contributes to causing a liquid-crystalline (LC) phase in low-molecular-weight or polymeric substances. Compounds containing mesogenic groups (mesogenic compounds) do not necessarily have to have a liquid-crystalline phase themselves. It is also possible for mesogenic compounds to exhibit liquid- crystalline phase behaviour only after mixing with other compounds and/or after polymerisation. Typical mesogenic groups are, for example, rigid rod- or disc-shaped units. An overview of the terms and definitions used in connection with mesogenic or liquid-crystalline compounds is given in Pure Appl. Chem. 73(5), 888 (2001 ) and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 1 16, 6340-6368. The term "spacer group" or "spacer" for short, also referred to as "Sp" above and below, is known to the person skilled in the art and is described in the literature, see, for example, Pure Appl. Chem. 73(5), 888 (2001 ) and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 1 16, 6340-6368. Unless indicated otherwise, the term "spacer group" or "spacer" above and below denotes a flexible group which connects the mesogenic group and the polymerisable group(s) to one another in a polymerisable mesogenic compound. For the purposes of this invention, the term "liquid-crystalline medium" is intended to denote a medium which comprises a liquid-crystal mixture and one or more polymerisable compounds (such as, for example, reactive mesogens). The term "liquid-crystal mixture" (or "host mixture") is intended to denote a liquid-crystalline mixture which consists exclusively of unpoly- merisable, low-molecular-weight compounds, preferably of two or more liquid-crystalline compounds and optionally further additives, such as, for example, chiral dopants or stabilisers.

Particular preference is given to liquid-crystal mixtures and liquid-crystal- line media which have a nematic phase, in particular at room temperature.

In a preferred embodiment of the present invention, the liquid-crystal medium comprises one or more dielectrically positive compounds having a dielectric anisotropy of greater than 3, selected from the group of the com- pounds of the formulae 11-1 and II-2:

n which the parameters have the respective meanings indicated above under formula II, and L²³ and L²⁴, independently of one another, denote H or F, preferably L²³ denotes F, and

and, in the case of formulae 11-1 and II-2, X² preferably denotes F or OCF3, particularly preferably F, and, in the case of formula II-2,

independently of one another, preferably denote

and/or selected from the group of the compounds of the formulae III-1 and III-2:

in which the parameters have the meanings given under formula III, and the media in accordance with the present invention may comprise, alternatively or in addition to the compounds of the formulae 111-1 and/or III-2, one or more compounds of the formula III-3

in which the parameters have the respective meanings indicated above, and the parameters L³¹ and L³², independently of one another and of the other parameters, denote H or F.

The liquid-crystal medium preferably comprises compounds selected from the group of the compounds of the formulae 11-1 and II-2 in which L²¹ and L²² and/or L²³ and L²⁴ both denote F. In a preferred embodiment, the liquid-crystal medium comprises compounds selected from the group of the compounds of the formulae 11-1 and II-2 in which L²¹, L²², L²³ and L²⁴ all denote F.

The liquid-crystal medium preferably comprises one or more compounds of the formula 11-1 . The compounds of the formula 11-1 are preferably selected from the group of the compounds of the formulae 11-1 a to 11-1 e, preferably one or more compounds of formulaell-1 a and/or 11-1 b and/or II- 1 d, preferably of formula 11-1 a and/or 11-1 d or 11-1 b and/or 11-1 d, most preferably of formula ll-1d:

in which the parameters have the respective meanings indicated above, and L²⁵ and L²⁶, independently of one another and of the other parameters, denote H or F, and preferably

in the formulae 11-1 a and 11-1 b,

L²¹ and L²² both denote F,

in the formulae 11-1 c and 11-1 cJ ,

L²¹ and L²² both denote F and/or L²³ and L²⁴ both denote F, and in formula 11-1 e,

L²¹, L²² and L²³ denote F.

The liquid-crystal medium preferably comprises one or more compounds of the formula II-2, which are preferably selected from the group of the compounds of the formulae ll-2a to ll-2k, preferably one or more compounds each of formulae ll-2a and/or ll-2h and/or ll-2j:

in which the parameters have the respective meanings indicated above, and L²⁵ to L²⁸, independently of one another, denote H or F, preferably L²⁷ and L²⁸ both denote H, particularly preferably L²⁶ denotes H. The liquid-crystal medium preferably comprises compounds selected from the group of the compounds of the formulae ll-2a to ll-2k in which L²¹ and L²² both denote F and/or L²³ and L²⁴ both denote F. In a preferred embodiment, the liquid-crystal medium comprises compounds selected from the group of the compounds of the formulae ll-2a to ll-2k in which L²¹, L²², L²³ and L²⁴ all denote F.

Especially preferred compounds of the formula II-2 are the compounds of the following formulae, particularly preferred of formulae ll-2a-1 and/or II- 2h-1 and/or ll-2k-2:

in which R² and X² have the meanings indicated above, and X² preferably denotes F. The liquid-crystal medium preferably comprises one or more compounds of the formula 111-1 . The compounds of the formula 111-1 are preferably selected from the group of the compounds of the formulae lll-1 a to lll-1j, preferably from formulae lll-1 c, lll-1f, lll-1 g and lll-1j:

in which the parameters have the meanings given above and preferably in which the parameters have the respective meanings indicated above, the parameters L³³ and L³⁴, independently of one another and of the other parameters, denote H or F and the parameters L³⁵ and L³⁶, independently of one another and of the other parameters, denote H or F.

The liquid-crystal medium preferably comprises one or more compounds of the formula lll-1 c, which are preferably selected from the group of the compounds of the formulae lll-1 c-1 to lll-1 c-5, preferably of formulae III- 1 c-1 and/or lll-1 c-2, most preferably of formula 111 - 1 c- 1 :

in which R³ has the meaning indicated above. The liquid-crystal medium preferably comprises one or more compounds of the formula lll-1f, which are preferably selected from the group of the compounds of the formulae lll-1f-1 to lll-1f-6, preferably of formulae III-1M and/or lll-1f-2 and/or lll-1f-3 and /or IIMf-6, more preferably of formula lll-1f-3 and/or lll-1f-6, more preferably of formula lll-1f-6:

in which R³ has the meaning indicated above. The liquid-crystal medium preferably comprises one or more compounds of the formula lll-1g, which are preferably selected from the group of the compounds of the formulae lll-1 g-1 to lll-1g-5, preferably of formula lll-1 g-3:

in which R³ has the meaning indicated above.

The liquid-crystal medium preferably comprises one or more compounds of the formula lll-1 h, which are preferably selected from the group of the compounds of the formulae lll-1 h-1 to lll-1 h-3, preferably of the formula lll-1 h-3:

in which the parameters have the meanings given above, and X³ preferably denotes F.

The liquid-crystal medium preferably comprises one or more compounds of the formula lll-1 i, which are preferably selected from the group of the compounds of the formulae lll-1 i-1 and lll-1 i-2, preferably of the formula ΙΙΙ-1 i-2:

in which the parameters have the meanings given above, and X³ preferably denotes F. The liquid-crystal medium preferably comprises one or more compounds of the formula lll-1j, which are preferably selected from the group of the compounds of the formulae lll-1j-1 and lll-1j-2, preferably of the formula lll-1j-1 :

in which the parameters have the meanings given above.

The liquid-crystal medium preferably comprises one or more compounds of the formula III-2. The compounds of the formula III-2 are preferably selected from the group of the compounds of the formulae lll-2a and lll-2b, preferably of formula lll-2b:

in which the parameters have the respective meanings indicated above, and the parameters L³³ and L³⁴, independently of one another and of the other parameters, denote H or F.

The liquid-crystal medium preferably comprises one or more compounds of the formula lll-2a, which are preferably selected from the group of the compounds of the formulae lll-2a-1 to lll-2a-6:

in which R³ has the meaning indicated above.

The liquid-crystal medium preferably comprises one or more compounds of the formula lll-2b, which are preferably selected from the group of the compounds of the formulae lll-2b-1 to lll-2b-4, preferably lll-2b-4:

in which R³ has the meaning indicated above. Alternatively or in addition to the compounds of the formulae 111-1 and/or III-2, the media in accordance with the present invention may comprise one or more compounds of the formula III-3

in which the parameters have the respective meanings indicated above under formula III.

These compounds are preferably selected from the group of the formulae lll-3a and lll-3b:

in which R³ has the meaning indicated above.

The liquid-crystalline media in accordance with the present invention preferably comprise one or more dielectrically neutral compounds having a dielectric anisotropy in the range from -1 .5 to 3, preferably selected from the group of the compounds of the formulae VI, VII, VIII and IX.

In the present application, the elements all include their respective isotopes. In particular, one or more H in the compounds may be replaced by D, and this is also particularly preferred in some embodiments. A correspondingly high degree of deuteration of the corresponding compounds enables, for example, detection and recognition of the compounds. This is very helpful in some cases, in particular in the case of the compounds of formula I.

In the present application, particularly preferably denotes straight-chain alkyl, in particular CH3-, C2H5-, n -C3H7-, n-C₄H₉- or n-C5H11-, and particularly preferably denotes CH₂=CH-, E-CH₃-CH=CH- CH₂=CH-CH₂-CH₂-, E-CH₃-CH=CH-CH₂-CH₂- or

E-(n-C₃H₇)-CH=CH-. In a preferred embodiment of the present invention, the media according to the invention in each case comprise one or more compounds of formula VI selected from the group of the compounds of the formulae VI-1 and VI- 2, preferably one or more compounds each of formulae VI-1 and one or more compounds of formula VI-2,

in which the parameters have the respective meanings given above under formula VI, and preferably

in formula VI-1

R⁶¹ and R⁶² independently of each other denote methoxy, ethoxy, propoxy, butoxy (also or pentoxy, preferably ethoxy, butoxy or pentoxy, more preferably ethoxy or butoxy and, most preferably butoxy. in formula VI-2

R⁶¹ preferably denotes vinyl, 1 -E-propenyl, but-4-en-1 -yl, pent-

1 -en-1 -yl or pent-3-en-1 -yl and n-propyl or n-pentyl and

R⁶² denotes an unsubstituted alkyl radical having 1 to 7 C

atoms, preferably having 2 to 5 C atoms, or, preferably, an unsubstituted alkoxy radical having 1 to 6 C atoms, particularly preferably having 2 or 4 C atoms and, most preferably, ethoxy, and

In a preferred embodiment of the present invention, the media according to the invention in each case comprise one or more compounds of formula VII selected from the group of the compounds of the formulae VII-1 to VII- 3, preferably one or more compounds each of the formulae VII-1 and one or more compounds of formula VII-2,

in which the parameters have the respective meanings given above under formula VII, and preferably R⁷¹ denotes vinyl, 1 -E-propenyl, but-4-en-1 -yl, pent-1 -en-1 -yl or pent-3-en-1 -yl, n-propyl or n-pentyl and

R⁷² denotes an unsubstituted alkyl radical having 1 to 7 C atoms, preferably having 2 to 5 C atoms, or, preferably, an unsubstituted alkoxy radical having 1 to 6 C atoms, particularly preferably having 2 or 4 C atoms and, most preferably, ethoxy.

In a preferred embodiment of the present invention, the media according to the invention in each case comprise one or more compounds of formula VI-1 selected from the group of the following compounds:

In a preferred embodiment of the present invention, the media according to the invention in each case comprise one or more compounds of formula VI-2 selected from the group of the following compounds:

In a preferred embodiment of the present invention, the media according to the invention in each case comprise one or more compounds of formula V II-1 selected from the group of the following compounds:

In a preferred embodiment of the present invention, the media according to the invention in each case comprise one or more compounds of formula VII-2 selected from the group of the following compounds:

In addition to the compounds of formula B or the preferred sub-formulae thereof, the media in accordance with the present invention preferably comprise one or more dielectrically negative compounds selected from the group of compounds of the formulae VI and VII preferably in a total concentration in the range from 5% or more to 90% or less, preferably from 10% or more to 80% or less, particularly preferably from 20% or more to 70% or less.

In a preferred embodiment of the present invention, the media according to the invention in each case comprise one or more compounds of formula VIII selected from the group of the compounds of the formulae VIII-1 to VIII-3, preferably one or more compounds each of the formulae VIII-1 and/or one or more compounds of formula VIII-3,

in which the parameters have the respective meanings given above under formula VIII, and preferably R⁸¹ denotes vinyl, 1 -E-propenyl, but-4-en-1 -yl, pent-1 -en-1 -yl or pent-3-en-1 -yl, ethyl, n-propyl or n-pentyl, alkyl, preferably ethyl, n-propyl or n-pentyl and

R⁸² denotes an unsubstituted alkyl radical having 1 to 7 C atoms, preferably having 1 to 5 C atoms or an

unsubstituted alkoxy radical having 1 to 6 C atoms.

In formulae VI 11-1 and VIII-2 R⁸² denotes preferably akioxy having 2 or 4 C atoms and, most preferably, ethoxy and in formula VIII-3 it denotes preferably alky, preferably methyl, ethyl or n-propyl, most preferably methyl.

In a further preferred embodiment, the medium comprises one or more compounds of formula IV, preferably of formula IVa

in which

_R41 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, preferably an n-alkyl radical, particularly preferably having 2, 3, 4 or 5 C atoms, and denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkenyl radical having 2 to 7 C atoms, or an unsubstituted alkoxy radical having 1 to 6 C atoms, both preferably having 2 to 5 C atoms, an unsubstituted alkenyl radical preferably having 2, 3 or 4 C atoms, more preferably a vinyl radical or 1 -propenyl radical and in particular a vinyl radical. In a particularly preferred embodiment, the medium comprises one or more compounds of formula IV selected from the group of the compounds of the formulae IV-1 to IV-4, preferably of formula IV-1 ,

in which alkyl and alkyl', independently of one another, denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms, alkenyl and alkenyl', independently of one another, denote alkenyl having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably 2 C atoms, alkenyl' preferably denotes alkenyl having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms, and alkoxy denotes alkoxy having 1 to 5 C atoms, preferably having 2 to 4 C atoms. In a particularly preferred embodiment, the media according to the invention comprise one or more compounds of formula IV-1 and/or one or more compounds of formula IV-2. In a further preferred embodiment, the medium comprises one or more compounds of formula V.

The media according to the invention preferably comprise the following compounds in the total concentrations indicated:

1 - 60 % by weight of one or more compounds selected from the group of the compounds of formula B and

60 % by weight of one or more compounds of formula I,

preferably selected from the group of the compounds of the formulae 1-1 and I-2, most preferably of formula I-2 and/or

60 % by weight of one or more compounds of formula II,

preferably selected from the group of the compounds of the formulae 11-1 and II-2 and/or

5 - 25 % by weight of one or more compounds of formula III, and/or 5 - 45 % by weight of one or more compounds of formula IV, and/or 5 - 25 % by weight of one or more compounds of formula V, and/or 5 - 25 % by weight of one or more compounds of formula VI, and/or 5 - 20 % by weight of one or more compounds of formula VII,

and/or

30 % by weight of one or more compounds of formula VIII,

preferably selected from the group of the compounds of the formulae VI 11-1 and VIII-2 and/or 0 - 60 % by weight of one or more compounds of formula IX where the total content of all compounds of formula B and of formulae I to IX, which are present in the medium, preferably is 95 % or more, more preferably 97 % or more and, most preferably, 100 %.

The latter condition holds for all media according to the present

application. In a further preferred embodiment, the media in accordance with the present invention in addition to the compounds of formula B or the preferred sub-formulae thereof, and to the compounds of formulae VI and/or VII and/or VIII and/or IX and/or I, preferably comprise one or more dielectrically neutral compounds selected from the group of compounds of formulae IV and V preferably in a total concentration in the range from 5 % or more to 90 % or less, preferably from 10 % or more to 80 % or less, particularly preferably from 20 % or more to 70 % or less.

The medium according to the invention in a particularly preferred embodiment comprises one or more compounds of formula B in a total concentration in the range from 3 % or more to 50 % or less, preferably in the range from 5 % or more to 30 % or less, and one or more compounds of formula I in a total concentration in the range from 3 % or more to 50 % or less, preferably in the range from 5 % or more to 30 % or less, and/or one or more compounds of formula II in a total concentration in the range from 5 % or more to 50 % or less, preferably in the range from 10 % or more to 40 % or less, and/or one or more compounds of formula VII-1 in a total concentration in the range from 5 % or more to 30 % or less, and/or one or more compounds of formula VII-2 in a total concentration in the range from 3 % or more to 30 % or less.

Preferably the concentration of the compounds of formula B in the media according to the invention is in the range from 1 % or more to 60 % or less, more preferably from 5 % or more to 40 % or less, most preferably from 8 % or more to 35 % or less.

In a preferred embodiment of the present invention the concentration of the compounds of formula I in the media according to the invention is in the range from 1 % or more to 60 % or less, more preferably from 5 % or more to 40 % or less, most preferably from 8 % or more to 35 % or less

In a preferred embodiment of the present invention the concentration of the compounds of formula II in the media is in the range from 3 % or more to 60 % or less, more preferably from 5 % or more to 55 % or less, more preferably from 10 % or more to 50 % or less and, most preferably, from 15 % or more to 45 % or less. In a preferred embodiment of the present invention the concentration of the compounds of formula VII in the media is in the range from 2 % or more to 50 % or less, more preferably from 5 % or more to 40 % or less, more preferably from 10 % or more to 35 % or less and, most preferably, from 15 % or more to 30 % or less.

In a preferred embodiment of the present invention the concentration of the compounds of formula VII-1 in the media is in the range from 1 % or more to 40 % or less, more preferably either from 2 % or more to 35 % or less, or, alternatively, from 15 % or more to 25 % or less.

In a preferred embodiment of the present invention the concentration of the compounds of formula VII-2 in the media, if present, is in the range from 1 % or more to 40 % or less, more preferably from 5 % or more to 35 % or less and, most preferably, from 10 % or more to 30 % or less. The present invention also relates to electro-optical displays or electro- optical components which contain liquid-crystalline media according to the invention. Preference is given to electro-optical displays which are based on the VA, ECB, IPS or FFS effect, preferably on the VA, IPS or FFS effect, and in particular those which are addressed by means of an active- matrix addressing device.

Accordingly, the present invention likewise relates to the use of a liquid- crystalline medium according to the invention in an electro-optical display or in an electro-optical component, and to a process for the preparation of the liquid-crystalline media according to the invention, characterised in that one or more compounds of formula B are mixed with one or more compounds of formula I, preferably with one or more compounds of the sub- formulae 1-1 and/or I-2, preferably of formula I-2 and/or one or more com- pounds of formula II, preferably with one or more compounds of the sub- formulae 11-1 and/or II-2 with one or more compounds of formula VII, preferably with one or more compounds of the sub-formulae VII-1 and/or VII-2, particularly preferably one or more compounds from two or more, preferably from three or more, different formulae thereof and very particularly preferably from all four of these formulae 11-1 , II-2, VII-1 and VII-2 and one or more further compounds, preferably selected from the group of the compounds of the formulae IV and V, more preferably with one or more compounds both of formula IV and of formula V. In a further preferred embodiment, the medium comprises one or more compounds of formula IV, selected from the group of the compounds of the formulae IV-2 and IV-3,

in which alkyl and alkyi, independently of one another, denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms, alkoxy denotes alkoxy having 1 to 5 C atoms, preferably having 2 to 4 C atoms.

In a further preferred embodiment, the medium comprises one or more compounds of formula V selected from the group of the compounds of the formulae V-1 and V-2, preferably of formulae V-1 ,

in which the parameters have the meanings given above under formula V, and preferably

R⁵¹ denotes alkyl having 1 to 7 C atoms or alkenyl having 2 to

7 C atoms, and R⁵² denotes alkyl having 1 to 7 C atoms, alkenyl having 2 to 7

C atoms or alkoxy having 1 to 6 C atoms, preferably alkyl or alkenyl, particularly preferably alkyl.

In a further preferred embodiment, the medium comprises one or more compounds of formula V-1 selected from the group of the compounds of the formulae V-1 a and V-1 b,

in which alkyl and alkyl', independently of one another, denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms, and alkenyl denotes alkenyl having 2 to 7 C atoms, preferably having

2 to 5 C atoms.

In addition, the present invention relates to a method for the reduction of the wavelength dispersion of the birefringence of a liquid-crystalline medium which comprises one or more compounds of formula II, optionally one or more compounds selected from the group of the compounds of the formulae VII-1 and VII-2 and/or one or more compounds of formula IV and/or one or more compounds of formula V, characterised in that one or more compounds of formula B are used in the medium.

Besides compounds of the formulae I to V, other constituents may also be present, for example in an amount of up to 45 %, but preferably up to 35 %, in particular up to 10 %, of the mixture as a whole.

The media according to the invention may optionally also comprise a di- electrically positive component, whose total concentration is preferably 20 % or less, more preferably 10 % or less, based on the entire medium.

In a preferred embodiment, the liquid-crystal media according to the invention comprise in total, based on the mixture as a whole,

1 % or more to 20 % or less, preferably 2 % or more to 15 % or less, particularly preferably 3 % or more to 12 % or less, of the compound of formula B, 1 % or more to 20 % or less, preferably 2 % or more to 15 % or less, particularly preferably 3 % or more to 12 % or less, of the compound of formula I, 20 % or more to 50 % or less, preferably 25 % or more to 45 % or less, particularly preferably 30 % or more to 40 % or less, of compounds of formulae II and/or III, and

0 % or more to 35 % or less, preferably 2 % or more to 30 % or less, par- ticularly preferably 3 % or more to 25 % or less, of compounds of formulae IV and/ or V, and

5 % or more to 50 % or less 10 % or more to 45 % or less, preferably 15 % or more to 40 % or less of compounds of the formulae VI and/or VII and/or VIII and/or IX.

The liquid-crystal media in accordance with the present invention may comprise one or more chiral compounds. Particularly preferred embodiments of the present invention meet one or more of the following conditions, where the acronyms (abbreviations) are explained in Tables A to C and illustrated by examples in Table D.

Preferably the media according to the present invention fulfil one or more of the following conditions. i. The liquid-crystalline medium has a birefringence of 0.060 or more, particularly preferably 0.070 or more. ii. The liquid-crystalline medium has a birefringence of 0.200 or less, particularly preferably 0.180 or less. iii. The liquid-crystalline medium has a birefringence in the range from 0.090 or more to 0.160 or less. The liquid-crystalline medium comprises one or more particularly preferred compounds of formula Bl, preferably selected from the (sub-) formulae B-1 and B-2, most preferably of (sub-)formula B-2.

The liquid-crystalline medium comprises one or more particularly preferred compounds of formula I, preferably selected from the (sub-) formulae 1-1 and I-2, most preferably of (sub-)formula I-2.

The total concentration of the compounds of formula II in the mixture as a whole is 25 % or more, preferably 30 % or more, and is preferably in the range from 25 % or more to 49 % or less, particularly preferably in the range from 29 % or more to 47 % or less, and very particularly preferably in the range from 37 % or more to 44 % or less. vii. The liquid-crystalline medium comprises one or more compounds of formula IV selected from the group of the compounds of the following formulae: CC-n-V and/or CC-n-Vm and/or CC-V-V and/or CC-V-Vn and/or CC-nV-Vn, particularly preferably CC-3-V, preferably in a concentration of up to 60 % or less, particularly preferably up to 50 % or less, and optionally additionally CC-3-V1 , preferably in a

concentration of up to 15 % or less, and/or CC-4-V, preferably in a concentration of up to 40 % or less, particularly preferably up to 30% or less. viii. The media comprise the compound of formula CC-n-V, preferably CC-3-V, preferably in a concentration of 1 % or more to 60 % or less, more preferably in a concentration of 3 % or more to 35 % or less. ix. The total concentration of the compounds of formula CC-3-V in the mixture as a whole preferably either is 15 % or less, preferably 10 % or less or 20 % or more, preferably 25 % or more. x. The total concentration of the compounds of formula Y-nO-Om in the mixture as a whole is 2 % or more to 30 % or less, preferably 5 % or more to 15 % or less. xi. The total concentration of the compounds of formula CY-n-Om in the mixture as a whole is 5 % or more to 60 % or less, preferably 15% or more to 45 % or less. xii. The total concentration of the compounds of formula CCY-n-Om and/ or CCY-n-m, preferably of CCY-n-Om, in the mixture as a whole is 5 % or more to 40 % or less, preferably 1 % or more to 25 % or less.

The total concentration of the compounds of formula CLY-n-Om in the mixture as a whole is 5 % or more to 40 % or less, preferably 10 % or more to 30 % or less. xiv. The liquid-crystalline medium comprises one or more compounds of formula IV, preferably of the formulae IV-1 and/or IV-2, preferably in a total concentration of 1 % or more, in particular 2 % or more, and very particularly preferably 3 % or more to 50 % or less, preferably

35 % or less. xv. The liquid-crystalline medium comprises one or more compounds of formula V, preferably of the formulae V-1 and/or V-2, preferably in a total concentration of 1 % or more, in particular 2 % or more, and very particularly preferably 15 % or more to 35 %or less, preferably to 30 % or less. xvi. The total concentration of the compounds of formula CCP-V-n,

preferably CCP-V-1 , in the mixture as a whole preferably is 5 % or more to 30 % or less, preferably 15 % or more to 25 % or less. xvii. The total concentration of the compounds of formula CCP-V2-n, preferably CCP-V2-1 , in the mixture as a whole preferably is 1 % or more to 15 % or less, preferably 2 % or more to 10 % or less. The invention furthermore relates to an electro-optical display having active-matrix addressing based on the VA, ECB, IPS, FFS or UB-FFS effect, characterised in that it contains, as dielectric, a liquid-crystalline medium in accordance with the present invention.

The liquid-crystal mixture preferably has a nematic phase range having a width of at least 70 degrees.

The rotational viscosity γ₁ is preferably 350 mPa s or less, preferably 250 mPa s or less and, in particular, 150 mPa s or less.

The mixtures according to the invention are suitable for all IPS and FFS- TFT applications using dielectrically positive liquid crystalline media, such as, e.g. SG-FFS.

The liquid-crystalline media according to the invention preferably virtually completely consist of 4 to 15, in particular 5 to 12, and particularly

preferably 10 or less, compounds. These are preferably selected from the group of the compounds of the formulae B, I, II, III, IV, V, VI, VII, VIII and IX.

The liquid-crystalline media according to the invention may optionally also comprise more than 18 compounds. In this case, they preferably comprise 18 to 25 compounds. In a preferred embodiment, the liquid-crystal media according to the invention predominantly comprise, preferably essentially consist of and, most preferably, virtually completely consist of compounds, which do not comprise a cyano group. In a preferred embodiment, the liquid-crystal media according to the invention comprise compounds selected from the group of the compounds of the formulae I, II, and II, IV and V and VI to IX, preferably selected from the group of the compounds of the formulae 1-1 , I-2, 11-1 , II-2, 111-1 , III-2, IV, V, VII-1 , VII-2, VIII and IX; they preferably consist predominantly,

particularly preferably essentially and very particularly preferably virtually completely of the compounds of the said formulae. The liquid-crystal media according to the invention preferably have a nematic phase from in each case at least -10°C or less to 70°C or more, particularly preferably from -20°C or less to 80°C or more, very particularly preferably from -30°C or less to 85°C or more and most preferably from -40°C or less to 90°C or more.

The expression "have a nematic phase" here means on the one hand that no smectic phase and no crystallisation are observed at low temperatures at the corresponding temperature and on the other hand that no clearing occurs on heating out of the nematic phase. The investigation at low temperatures is carried out in a flow viscometer at the corresponding temperature and checked by storage in test cells having a cell thickness corresponding to the electro-optical application for at least 100 hours. If the storage stability at a temperature of -20°C in a corresponding test cell is 1000 h or more, the medium is regarded as stable at this temperature. At temperatures of -30°C and -40°C, the corresponding times are 500 h and 250 h respectively. At high temperatures, the clearing point is measured in capillaries by conventional methods.

In a preferred embodiment, the liquid-crystal media according to the invention are characterised by optical anisotropy values in the moderate to low range. The birefringence values are preferably in the range from 0.075 or more to 0.130 or less, particularly preferably in the range from 0.085 or more to 0.120 or less and very particularly preferably in the range from 0.090 or more to 0.1 15 or less.

In this embodiment, the liquid-crystal media according to the invention have a positive dielectric anisotropy and relatively high absolute values of the dielectric anisotropy Δε, which preferably is in the range from 2.0 or more to 20 or less, more preferably to 15 or less, more preferably from 3.0 or more to 10 or less, particularly preferably from 4.0 or more to 9.0 or less and very particularly preferably from 4.5 or more to 8.0 or less. The liquid-crystal media according to the invention preferably have relatively low values for the threshold voltage (Vo) in the range from 1 .0 V or more to 5.0 V or less, preferably to 2.5 V or less, preferably from 1 .2 V or more to 2.2 V or less, particularly preferably from 1 .3 V or more to 2.0 V or less. In a further preferred embodiment, the liquid-crystal media according to the invention preferably have relatively high values of the average dielectric constant (ε_av.≡ (ε| | + 2ε±)/3) which are preferably in the range from 8.0 or more to 25.0 or less, preferably from 8.5 or more to 20.0 or less, still more preferably from 9.0 or more to 19.0 or less, particularly preferably from 10.0 or more to 18.0 or less and very particularly

preferably from 1 1 .0 or more to 16.5 or less.

In addition, the liquid-crystal media according to the invention have high values for the VHR in liquid-crystal cells.

In freshly filled cells at 20°C in the cells, the values of the VHR of these media are greater than or equal to 95 %, preferably greater than or equal to 97%, particularly preferably greater than or equal to 98 % and very particularly preferably greater than or equal to 99 %, and after 5 minutes in the oven at 100°C in the cells, these are greater than or equal to 90 %, preferably greater than or equal to 93 %, particularly preferably greater than or equal to 96 % and very particularly preferably greater than or equal to 98 %. In general, liquid-crystal media having a low addressing voltage or threshold voltage here have a lower VHR than those having a higher addressing voltage or threshold voltage, and vice versa.

These preferred values for the individual physical properties are preferably also in each case maintained by the media according to the invention in combination with one another.

In the present application, the term "compounds", also written as "com- pound(s)", means both one and also a plurality of compounds, unless explicitly indicated otherwise. In a preferred embodiment, the liquid-crystalline media according to the invention comprise one or more compounds of formula B, preferably selected from the group of formulae CB-n-F, CB-n-OT, CB-n-T, LB-n-F, LB-n-OT and LB-n-T, more preferably selected from the group of formulae CB-n-OT, CB-n-T, LB-n-OT and LB-n-T, preferably selected from the group of formulae CB-n-OT, CB- n-T, and one or more compounds of formula I, preferably selected from the group of the formulae B-nO-Om, B(S)-nO-Om, B-nO-OT, B-nO-T, B-n-OT and B-n- F, more preferably selected from the group of formulae B-nO-OT, B-nO-T, B-n-OT and B-n-F, and/or one or more compounds of formula II, preferably selected from the group of formulae PUQU-n-F, CDUQU-n-F, APUQU-n-F and PGUQU-n-F, and/or one or more compounds of formula III, preferably selected from the group of formulae CCP-n-OT, CGG-n-F, and CGG-n-OD, and/or one or more compounds of formulae IV and/or V, preferably selected from the group of formulae CC-n-V, CCP-n-m, CCP-V-n, CCP-V2-n and CGP- n-n and/or one or more compounds of formula VI, preferably selected from the group of formulae Y-n-Om, Y-nO-Om and/or CY-n-Om, preferably selected from the group of the compounds of the formulae Y-3-O1 , Y-4O-O4, CY-3-O2, CY-3-O4, CY-5-O2 and CY-5-O4, and/or optionally, preferably obligatorily, one or more compounds of formula VII- 1 , preferably selected from the group of compounds of the formulae CCY- n-m and CCY-n-Om, preferably of formula CCY-n-Om, preferably selected from the group of the compounds of the formulae CCY-3-O2, CCY-2-O2, CCY-3-O1 , CCY-3-O3, CCY-4-O2, CCY-3-O2 and CCY-5-O2, and/or optionally, preferably obligatorily, one or more compounds of formula VII- 2, preferably of formula CLY-n-Om, preferably selected from the group of the compounds of the formulae CLY-2-O4, CLY-3-O2, CLY-3-O3, and/or one or more compounds of formula VIII, preferably selected from the group of formulae CZY-n-On and CCOY-n-m and/or one or more compounds of formula IX, preferably selected from the group of formulae PYP-n-m, PYP-n-mVI and PYP-n-mVI, preferably selected from the group of formulae PYP-2-3, PYP-2-4, PYP-2-5, PYP-2-V and PYP-2-2V1 , and/or one or more compounds selected from the group of formulae PGP-n-m, PGP-n-V, PGP-n-Vm, PGP-n-mV and PGP-n-mVI, preferably selected from the group of formulae PGP-2-3, PGP-2-4, PGP-2-5, PGP-1 -V, PGP- 2-V and PGP-2-2V1 , and/or optionally, preferably obligatorily, one or more compounds of formula IV, preferably selected from the group of the compounds of the formulae CC- n-V, CC-n-Vm, CC-n-mVI and CC-nV-Vm, preferably CC-3-V, CC-3-V1 , CC-4-V, CC-5-V, CC-3-2V1 and CC-V-V, particularly preferably selected from the group of the compounds CC-3-V, CC-3-V1 , CC-4-V, CC-3-2V1 and CC-V-V, very particularly preferably the compound CC-3-V, and optionally additionally the compound(s) CC-4-V and/or CC-3-V1 and/or CC-3-2V1 and/or CC-V-V, and/or optionally, preferably obligatorily, one or more compounds of formula V, preferably selected from the group of formulae CCP-V-1 and/or CCP-V2-1 . In a specific preferred embodiment of the present invention, the media according to the invention comprise one or more compounds of formula IX,

The compounds of formula IX, are also highly suitable as stabilisers in liquid-crystal mixtures, especially in case p = q = 1 and ring A⁹ = 1 ,4- phenylene. In particular, they stabilise the VHR of the mixtures against UV exposure.

In a preferred embodiment the media according to the invention comprise one or more compounds of formula IX selected from one or more formulae of the group of the compounds of the formulae IX-1 to IX-4, very particularly preferably of the formulae IX-1 to IX-3,

in which the parameters have the meanings given under formula IX.

In a further preferred embodiment, the medium comprises one or more compounds of formula IX-3, preferably of formula IX-3-a,

in which alkyl and alkyl', independently of one another, denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms.

In case the compounds of formula IX are used in the liquid crystalline media according to the present application, they are preferably present in a concentration of 20 % or less, more preferably of 10 % or less and, most preferably, of 5 % or less and for the individual i.e. (homologous) compounds preferably in a concentration of 10 % or less and, more preferably, of 5 % or less.

For the present invention, the following definitions apply in connection with the specification of the constituents of the compositions, unless indicated otherwise in individual cases:

- "comprise": the concentration of the constituents in question in the composition is preferably 5% or more, particularly preferably 10% or more, very particularly preferably 20% or more,

- "predominantly consist of: the concentration of the constituents in question in the composition is preferably 50% or more, particularly preferably 55% or more and very particularly preferably 60% or more,

- "essentially consist of: the concentration of the constituents in

question in the composition is preferably 80% or more, particularly preferably 90% or more and very particularly preferably 95% or more, and

"virtually completely consist of: the concentration of the constituents in question in the composition is preferably 98% or more, particularly preferably 99% or more and very particularly preferably 100.0%.

This applies both to the media as compositions with their constituents, which can be components and compounds, and also to the components with their constituents, the compounds. Only in relation to the concentration of an individual compound relative to the medium as a whole does the term comprise mean: the concentration of the compound in question is preferably 1 % or more, particularly preferably 2% or more, very particularly preferably 4% or more.

For the present invention, "<" means less than or equal to, preferably less than, and ">" means greater than or equal to, preferably greater than.

For the present invention

denote trans-1,4-cyclohexylene,

denotes a mixture of both cis- and trans-1 , 4-cyclohexylene, and

denote 1 ,4-phenylene.

For the present invention, the expression "dielectrically positive compounds" means compounds having a Δε of > 1 .5, the expression "dielectrically neutral compounds" means those where -1 .5≤ Δε≤ 1 .5 and the expression "dielectrically negative compounds" means those where

Δε < -1 .5. The dielectric anisotropy of the compounds is determined here by dissolving 10% of the compounds in a liquid-crystalline host and determining the capacitance of the resultant mixture in each case in at least one test cell having a cell thickness of 20 μιτι with homeotropic and with homogeneous surface alignment at 1 kHz. The measurement voltage is typically 0.5 V to 1 .0 V, but is always lower than the capacitive threshold of the respective liquid-crystal mixture investigated. The host mixture used for dielectrically positive and dielectrically neutral compounds is ZLI-4792 and that used for dielectrically negative compounds is ZLI-2857, both from Merck KGaA, Germany. The values for the respective compounds to be investigated are obtained from the change in the dielectric constant of the host mixture after addition of the compound to be investigated and extrapolation to 100% of the compound employed. The compound to be investigated is dissolved in the host mixture in an amount of 10%. If the solubility of the substance is too low for this purpose, the concentration is halved in steps until the investigation can be carried out at the desired temperature.

The liquid-crystal media according to the invention may, if necessary, also comprise further additives, such as, for example, stabilisers and/or pleo- chroitic, e.g. dichroitic, dyes and/or chiral dopants in the usual amounts. The amount of these additives employed is preferably in total 0 % or more to 10 % or less, based on the amount of the entire mixture, particularly preferably 0.1 % or more to 6 % or less. The concentration of the individual compounds employed is preferably 0.1 % or more to 3 % or less. The concentration of these and similar additives is generally not taken into account when specifying the concentrations and concentration ranges of the liquid-crystal compounds in the liquid-crystal media.

In a preferred embodiment, the liquid-crystal media according to the invention comprise a polymer precursor which comprises one or more reactive compounds, preferably reactive mesogens, and, if necessary, also further additives, such as, for example, polymerisation initiators and/or polymerisation moderators, in the usual amounts. The amount of these additives employed is in total 0 % or more to 10 % or less, based on the amount of the entire mixture, preferably 0.1 % or more to 2 % or less. The concentration of these and similar additives is not taken into account when specify- ing the concentrations and concentration ranges of the liquid-crystal compounds in the liquid-crystal media. The compositions consist of a plurality of compounds, preferably 3 or more to 30 or fewer, particularly preferably 6 or more to 20 or fewer and very particularly preferably 10 or more to 16 or fewer compounds, which are mixed in a conventional manner. In general, the desired amount of the components used in lesser amount is dissolved in the components making up the principal constituent of the mixture. This is advantageously carried out at elevated temperature. If the selected temperature is above the clearing point of the principal constituent, completion of the dissolution operation is particularly easy to observe. However, it is also possible to prepare the liquid-crystal mixtures in other conventional ways, for example using pre-mixes or from a so-called "multi-bottle system".

The mixtures according to the invention exhibit very broad nematic phase ranges having clearing points of 65°C or more, very favourable values for the capacitive threshold, relatively high values for the holding ratio and at the same time very good low-temperature stabilities at -30°C and -40°C. Furthermore, the mixtures according to the invention are distinguished by low rotational viscosities γι .

It goes without saying to the person skilled in the art that the media according to the invention for use in VA, IPS, FFS or PALC displays may also comprise compounds in which, for example, H, N, O, CI, F have been replaced by the corresponding isotopes.

The structure of the liquid-crystal displays according to the invention corresponds to the usual geometry, as described, for example, in

EP-A 0 240 379. The liquid-crystal phases according to the invention can be modified by means of suitable additives in such a way that they can be employed in any type of, for example, IPS and FFS LCD display that has been disclosed to date. Table E below indicates possible dopants which can be added to the mixtures according to the invention. If the mixtures comprise one or more dopants, it is (they are) employed in amounts of 0.01 % to 4 %, preferably 0.1 % to 1 .0 %.

Stabilisers which can be added, for example, to the mixtures according to the invention, preferably in amounts of 0.01 % to 6 %, in particular 0.1 % to 3 %, are shown below in Table F.

For the purposes of the present invention, all concentrations are, unless explicitly noted otherwise, indicated in per cent by weight and relate to the corresponding mixture as a whole or mixture component, again a whole, unless explicitly indicated otherwise. In this context the term "the mixture" describes the liquid crystalline medium.

All temperature values indicated in the present application, such as, for example, the melting point T(C,N), the smectic (S) to nematic (N) phase transition T(S,N) and the clearing point T(N,I), are indicated in degrees Celsius (°C) and all temperature differences are correspondingly indicated in differential degrees (° or degrees), unless explicitly indicated otherwise. For the present invention, the term "threshold voltage" relates to the capa- citive threshold (Vo), also known as the Freedericks threshold, unless explicitly indicated otherwise.

All physical properties are and have been determined in accordance with "Merck Liquid Crystals, Physical Properties of Liquid Crystals", status Nov. 1997, Merck KGaA, Germany, and apply for a temperature of 20°C, and Δη is determined at 436 nm, 589 nm and at 633 nm, and Δε at 1 kHz, unless explicitly indicated otherwise in each case. The electro-optical properties, for example the threshold voltage (Vo)

(capacitive measurement), are, as is the switching behaviour, determined in test cells produced at Merck Japan. The measurement cells have soda- lime glass substrates and are constructed in an ECB or VA configuration with polyimide alignment layers (SE-121 1 with diluent ^**26 (mixing ratio 1 :1 ), both from Nissan Chemicals, Japan), which have been rubbed perpendicularly to one another and effect homeotropic alignment of the liquid crystals. The surface area of the transparent, virtually square ITO electrodes is 1 cm².

Unless indicated otherwise, a chiral dopant is not added to the liquid- crystal mixtures used, but the latter are also particularly suitable for applications in which doping of this type is necessary.

The rotational viscosity is determined using the rotating permanent magnet method and the flow viscosity in a modified Ubbelohde

viscometer. For liquid-crystal mixtures ZLI-2293, ZLI-4792 and MLC-6608, all products from Merck KGaA, Darmstadt, Germany, the rotational viscosity values determined at 20°C are 161 mPa s, 133 mPa s and 186 mPa-s respectively, and the flow viscosity values (v) are 21 mm²-s^"1, 14 mm²-s^"1 and 27 mm²-s^"1, respectively.

The dispersion of the materials may for practical purposes be conveniently characterized in the following way, which is used throughout this

application unless explicitly stated otherwise. The values of the

birefringence are determined at a temperature of 20°C at several fixed wavelengths using a modified Abbe refractometer with homeotropically aligning surfaces on the sides of the prisms in contact with the material. The birefringence values are determined at the specific wavelength values of 436 nm (respective selected spectral line of a low pressure mercury lamp), 589 nm (sodium "D" line) and 633 nm (wavelength of a HE-Ne laser (used in combination with an attenuator/diffusor in order to prevent damage to the eyes of the observers. In the following table Δη is given at 589 nm and Δ(Δη) is given as Δ(Δη) = Δη(436 nm) - Δη(633 nm).

The following symbols are used, unless explicitly indicated otherwise:

Vo threshold voltage, capacitive [V] at 20°C,

n_e extraordinary refractive index measured at 20°C and 589 nm, n₀ ordinary refractive index measured at 20°C and 589 nm,

Δη optical anisotropy measured at 20°C and 589 nm,

λ wavelength λ [nm],

Δη(λ) optical anisotropy measured at 20°C and wavelength λ, Δ(Δη) change in optical anisotropy defined as:

An(20°C, 436 nm) - An(20°C, 633 nm),

Δ(Δη^*) "relative change in optical anisotropy" defined as:

Δ(Δη)/Δη(20°Ο,589 nm),

ε± dielectric susceptibility perpendicular to the director at 20°C and 1 kHz,

ε | | dielectric susceptibility parallel to the director at 20°C and

1 kHz,

Δε dielectric anisotropy at 20°C and 1 kHz,

T(N,I) or dp. clearing point [°C],

v flow viscosity measured at 20°C [mm²-s^"1],

γι rotational viscosity measured at 20°C [mPa s],

kn elastic constant, "splay" deformation at 20°C [pN],

k22 elastic constant, "twist" deformation at 20°C [pN],

k₃3 elastic constant, "bend" deformation at 20°C [pN],

LTS low-temperature stability of the phase, determined in test cells,

VHR voltage holding ratio,

AVHR decrease in the voltage holding ratio, and

S_rel relative stability of the VHR,

The following examples explain the present invention without limiting it. However, they show the person skilled in the art preferred mixture concepts with compounds preferably to be employed and the respective con- centrations thereof and combinations thereof with one another. In addition, the examples illustrate the properties and property combinations that are accessible.

For the present invention and in the following examples, the structures of the liquid-crystal compounds are indicated by means of acronyms, with the transformation into chemical formulae taking place in accordance with Tables A to C below. All radicals Ο_ηΗ_2η+ι, C_mH_2m+i and QH21+1 or C_nH_2r„ C_mH_2m and QH2i are straight-chain alkyl radicals or alkylene radicals, in each case having n, m and I C atoms respectively. Preferably n, m and I are independently of each other 1 , 2, 3, 4, 5, 6, or 7. Table A shows the codes for the ring elements of the nuclei of the compound, Table B lists the bridging units, and Table C lists the meanings of the symbols for the left- and right-hand end groups of the molecules. The acronyms are composed of the codes for the ring elements with optional linking groups, followed by a first hyphen and the codes for the left-hand end group, and a second hyphen and the codes for the right-hand end group. Table D shows illustrative structures of compounds together with their respective abbreviations.

5

10

15

25 ou

35

in which n and m are each integers, and the three dots

holders for other abbreviations from this table.

Besides the compounds of formula B, the mixtures according to the invention preferably comprise one or more compounds of the compounds mentioned below.

The following abbreviations are used:

(n, m, k and I are, independently of one another, each an integer, preferably 1 to 9 preferably 1 to 7, k and I possibly may be also 0 and preferably are 0 to 4, more preferably 0 or 2 and most preferably 2, n preferably is 1 , 2, 3, 4 or 5, in the combination "-nO-" it preferably is 1 , 2, 3 or 4, preferably 2 or 4, m preferably is 1 , 2, 3, 4 or 5, in the combination "- Om" it preferably is 1 , 2, 3 or 4, more preferably 2 or 4. The combination "- IVm" preferably is "2V1 ".)

Table D

Exemplary, preferred compounds of formula B having a high ε±:

Exemplary, preferred compounds of formula I having a high ε±:

Exemplary, preferred dielectrically positive compounds

Table E shows chiral dopants which are preferably employed in the mixtures according to the invention.

Table E

In a preferred embodiment of the present invention, the media according to the invention comprise one or more compounds selected from the group of the compounds from Table E.

Table F shows stabilisers which can preferably be employed in the mixtures according to the invention in addition to the compounds of formula B. The parameter n here denotes an integer in the range from 1 to 12. In particular, the phenol derivatives shown can be employed as additional stabilisers since they act as antioxidants.

Table F

In a preferred embodiment of the present invention, the media according to the invention comprise one or more compounds selected from the group of the compounds from Table F, in particular one or more compounds selected from the group of the compounds of the following two formulae

Examples

The following examples explain the present invention without restricting it in any way. However, the physical properties make it clear to the person skilled in the art what properties can be achieved and in what ranges they can be modified. In particular, the combination of the various properties which can preferably be achieved is thus well defined for the person skilled in the art.

Synthesis examples

Exemplary compounds of formula B (having a high dielectric constant perpendicular to the director (s±))are synthesized.

Synthesis Example 1

Synthesis of 4,6-Difluoro-3-(4-propyl-cyclohex-1 -enyl)-7-trifluoromethoxy- dibenzofuran:

Step 1 .1 : 3,2',3'-Trifluoro-4-trifluoromethoxy-biphenyl-2-ol

A mixture of 6-bromo-2-fluoro-3-trifluoromethoxyphenol (2) (100 g, 0.36 mol), potassium carbonate (75 g, 0.54 mol), tris(dibenzylideneacetone)- dipalladium(O) (1 .6 g, 1 .7 mmol) and CataCXium A (2.0 g, 5.3 mmol) in THF (500 ml_) and distilled water (250 ml_) is heated to reflux under nitrogen atmosphere, followed by dropwise addition of a solution of 2,3- difluoro-4-phenylboronic acid (1 ) (63 g, 0.38 mol) in THF (250 ml_). The reaction mixture is heated at reflux temperature overnight. Then it is cooled to room temperature and diluted with MTB ether and distilled water. Throughout this application, unless explicitly stated otherwise, room temperature and ambient temperature are used synonymously and signify a temperature of about 20°C, typically (20 ± 1 )°C. The aqueous phase is separated and extracted with MTB ether. The combined organic phases are washed with distilled water and brine, dried (sodium sulphate) and concentrated in vacuo. The residue is purified by silica gel

chromatography (solvent dichloromethane followed by 1 -chlorobutane). 3,2\3'-Trifluoro-4-trifluoromethoxy-biphenyl-2-ol (3) is isolated as a brown solid.

Step 1 .2: 4,6-Difluoro-3-trifluoromethoxy-dibenzofuran

A mixture of 3,2',3'-trifluoro-4-trifluoromethoxy-biphenyl-2-ol (3) (1 1 .0 g, 35 mmol) and potassium phosphate monohydrate (10.0 g, 44 mmol) in DMPU (300 mL) is stirred at 1 10°C for 16 h. Then it is cooled to room

temperature and diluted with MTB ether and distilled water. The aqueous phase is separated and extracted with MTB ether. The combined organic phases are washed with distilled water and brine, dried (sodium sulphate) and concentrated in vacuo. The residue is purified by silica gel

chromatography (solvent 1 -chlorobutane) to give 4,6-difluoro-3- trifluoromethoxy-dibenzofuran (4) as yellowish crystals.

Step 1 .3: 1 -(4,6-Difluoro-7-trifluoromethoxy-dibenzofuran-3-yl)-4-propyl- cyclohexanol

n-Butyllithium (27 mL, 15% in hexane, 43 mmol) is added to a solution of 4,6-difluoro-3-trifluoromethoxy-dibenzofuran (4) (10.3 g, 34 mmol) in THF (100 mL) at -70°C under nitrogen atmosphere. A solution of 4- propylcyclohexanone (6.0 g, 43 mmol) in THF (100 mL) is added after 1 h, and the reaction mixture is stirred for 2 h at -70°C. Then it is allowed to warm to room temperature and is stirred for additional 72 h. The reaction is quenched with distilled water and hydrochloric acid (2 N) at 0°C and diluted with MTB ether. The aqueous phase is separated and extracted with MTB ether. The combined organic phases are washed with distilled water and brine, dried (sodium sulphate) and concentrated in vacuo. The residue is purified by silica gel chromatography (solvent 1 -chlorobutane) to give 1 -(4,6-difluoro-7-trifluoromethoxy-dibenzofuran-3-yl)-4-propyl- cyclohexanol (5) as yellow crystals.

Step 1 .4: 4,6-Difluoro-3-(4-propyl-cyclohex-1 -enyl)-7-trifluoromethoxy- dibenzofuran

A mixture of 1 -(4,6-difluoro-7-trifluoromethoxy-dibenzofuran-3-yl)-4-propyl- cyclohexanol (5) (7.9 g, 1 5 mmol) and toluene-4-sulfonic acid

monohydrate (300 mg, 1 .7 mmol) in toluene (1 00 mL) is heated in a Dean Stark trap at reflux temperature overnight. Then it is cooled to room temperature and diluted with MTB ether and distilled water. The aqueous phase is separated and extracted with MTB ether. The combined organic phases are washed with distilled water and brine, dried (sodium sulphate) and concentrated in vacuo. The residue is purified by silica gel

chromatography (solvent 1 -chlorobutane). Subsequent recrystallization of the crude product from methanol/heptane and ethanol results in colorless crystals of 4,6-difluoro-3-(4-propyl-cyclohex-1 -enyl)-7-trifluoromethoxy- dibenzofuran (B-2-A). This compounds has the following phase

characteristics:

K 62°C SA 1 21 °C I .

Synthesis Example 2

Synthesis of 4,6-Difluoro-3-(4-propyl-cyclohexyl)-7-trifluoromethoxy- dibenzofuran:

Step 2.1 : 4,6-Difluoro-3-(4-propyl-cyclohexyl)-7-trifluoromethoxy- dibenzofuran

4,6-Difluoro-3-(4-propyl-cyclohex-1 -enyl)-7-trifluoronnethoxy-dibenzofuran (B-2-A) (2.4 g, 6 mmol) in toluene (30 mL) is reacted with hydrogen in the presence of a catalytic amount of Palladium on activated charcoal for 24 h. The reaction mixture is concentrated in vacuo, and the residue is purified by silica gel chromatography (solvent 1 -chlorobutane) to give the transformer of the desired product. 4,6-Difluoro-3-(4-propyl-cyclohexyl)-7- trifluoromethoxy-dibenzofuran (B-1 -A) is isolated as colorless crystals after subsequent recrystallization from ethanol and heptane.

This compound has the following phase characteristics:

T_g -49°C K 69°C S_A 86°C N 98°C I.

Synthesis Example 3

Synthesis of 4,6-Difluoro-3-(4-propyl-cyclohex-1 -enyl)-7-trifluoromethyl- dibenzofuran:

4,6-Difluoro-3-(4-propyl-cyclohex-1 -enyl)-7-trifluoromethyl-dibenzofuran (B-2-B) is synthesized in analogy to 4,6-Difluoro-3-(4-propyl-cyclohex-1 - enyl)-7-trifluoronnethoxy-dibenzofuran (B-2-A), starting from 6-bromo-2- fluoro-3-trifluoromethylphenol and 2,3-difluoro-4-phenylboronic acid (1 ). Recrystallization of the crude product from heptane gives colorless crystals of 4,6-difluoro-3-(4-propyl-cyclohex-1 -enyl)-7-trifluoromethyl- dibenzofuran (B-2-B). This compounds has the following phase characteristics:

K 89°C S_A 108°C I.

Synthesis Example 4

Synthesis of 4,6-Difluoro-3-(4-propyl-cyclohexyl)-7-trifluoromethyl- dibenzofuran:

This compounds is prepared analogously to the compound of synthesi example 2. It has the following phase characteristics:

K 1 16°C S_A (64°C) N (84.4°C) I.

Synthesis Example 5

Synthesis of 4,6,7-Trfluoro-3-(4-propyl-cyclohex-1 -enyl)dibenzofuran:

This compounds is prepared analogously to the compounds of synthesis examples 1 and 3. It has the following phase characteristics:

K 103°C N (93.0°C) I.

Synthesis Example 6

Synthesis of 4,6,7-Trifluoro-3-(4-propyl-cyclohexyl)dibenzofuran:

This compounds is prepared analogously to the compounds of synthesis examples 2 and 4. It has the following phase characteristics:

K 123°C N (106.4°C) I.

Analogously are prepared compounds of the formula B-1

wherein

Analogously are prepared compounds of the formula B-2

wherein

Compound examples

Exemplary compounds having a high dielectric constant perpendicular to the director (ε±) and a high average dielectric constant (s_av.) are

exemplified in the following compound examples.

Compound examples B1 .1 to B1 .3 Compounds of formula B-1 are e.g.

This compound (CB-3-OT) has a glass transition temperature (T_g) of -49°C, a melting point of 69°C, an extrapolated clearing point (5 % in ZLI- 4792 ) of 102°C, a phase sequence of T_g -49°C K 69°C S_A 86°C N 98 C I, a Δε of 1 .7 and an ε± of 10.5.

Compound examples B1 .4 to B1 .6

This compound (LB-3-OT) has a melting point of 62°C, an extrapolated clearing point (5 % in ZLI-4792) of 97°C, a phase sequence of K 62°C S_A 121 °C I, a Δε of 2.5 and an ε± of 10.5.

This compound (LB-3-T) has a melting point of 89°C, a phase sequence of K 89°C S_A 108°C I, an extrapolated clearing point (10 % in ZLI-4792) of 83°C, a Δε of 3.5 and an ε± of 12.5.

Examples of additional compounds 1 .1 and 1 .2

Compounds of formula 1-1 are e.g.

This compound (B-2O-O5) has a melting point of 57°C, a Δε of -13.7 and an ε_av. of even 17.9.

This compound (B-4O-O5) has similar preferably properties.

Examples of additional compounds 2.1 and 2.2

Two compounds of formula I-2 are e.g.

This compound (B-5O-OT) has a melting point of 68°C, a Δε of only -3.7 and an ε_av. of even 18.6.

This compound (B-6O-OT) has a melting point of 72°C.

Examples of additional compounds 3.1 to 3.6

Further compounds of formula 1-1 are e.g.

This compound (B-4-4) has a melting point of 38°C.

This compound (B-5-2V) has a melting point of 35°C.

This compound (B-V2-2V) has a melting point of 60°C

This compound (B-2-O2) has a melting point of 60°C.

This compound (B-3-O3) has a melting point of 54°C.

This compound (B-3-O2V) has a melting point of 50°C.

Examples of additional compounds 4.1 to 4.1 1

Further compounds of formula I-2 are e.g

This compound (B-3-F) has a melting point of 76°C.

This compound (B-5-F) has a melting point of 42°C.

This compound (B-5-T) has a melting point of 46°C.

This compound (B-5-OT) has a melting point of 46°C.

This compound (B-2O-F) has a melting point of 1 14°C.

This compound (B-5O-F) has a melting point of 65°C.

This compound (B-5O-CI) has a melting point of 51 °C.

This compound (B-4O-T) has a melting point of 81 °C

This compound (B-5O-T) has a melting point of 74°C.

This compound (B-6O-T) has a melting point of 76°C.

This compound (B-V2O-OT) has a melting point of 87°C.

Examples of additional compounds 5.1 to 5.3

Compounds of formula I, wherein n is 1 are e.g.

This compound (CB-3-O4) has a phase range of K 76°C N 145.6°C I.

This compound (PB-3-O4) has a phase range of K 122°C N (121 .6°C) I.

This compound (GB-4-O2) has a phase range of K 69°C N (34.5°C) I. Mixture Examples

In the following exemplary mixtures are disclosed.

Comparative Example A

The following mixture (CE-A) is prepared and investigated.

Remark: t.b.d.: to be determined Table 1

Remarks: all extrapolated values at 20°C,

*: [mPa s/pN] and t.b.d.: to be determined Table 1 (continued)

These mixtures, mixtures A-1 to A-6, have good dielectric ratios (ε±/Δε), good ratios of (γι/kn) and are characterized by very good transmissions in an FFS display and show very short response time. Moreover, they show excellent deep temperature stability at least up to a temperature of -20°C. Table 1 (continued)

Table 1 (continued)

Table 1 (continued)

Remarks: all extrapolated values at 20°C,

Pa s/pN] and t.b.d.: to be determined Table 1 (continued)

Remarks: all extrapolated values at 20°C,

Pa s/pN] and t.b.d.: to be determined Comparative Example B

The following mixture (CE-B) is prepared and investigated.

Remark: t.b.d.: to be determined Table 2

Remarks: all extrapolated values at 20°C,

*: [mPa s/pN] and t.b.d.: to be determined. Table 2 (continued)

Remarks: all extrapolated values at 20°C,

^*: [mPa s/pN] and t.b.d.: to be determined

These mixtures, mixtures B-1 to B-6, have good dielectric ratios (ε±/Δε), good ratios of (γι/kn) and are characterized by very good transmissions in an FFS display and show very short response time. Moreover, they show excellent deep temperature stability at least up to a temperature of -20°C. Comparative Example C

The following mixture (CE-C) is prepared and investigated.

Remark: t.b.d.: to be determined

Table 3

Remarks: all extrapolated values at 20°C,

*: [mPa s/pN] and t.b.d.: to be determined Example 3

The following mixture (M-3) is prepared and investigated.

This mixture, mixture M-3, has a dielectric ratio (ε±/Δε) of 0.87, a ratio of (y₁/k₁₁) of 4.28 mPa s / pN and is characterized by a very good transmission in an FFS display, shows a very short response time, and has a very good low temperature stability. Example 4

The following mixture (M-4) is prepared and investigated.

This mixture, mixture M-4, has a dielectric ratio (ε±/Δε) of 1 .02, a ratio of (yi/kn) of 4.48 mPa s / pN and is characterized by a very good transmission in an FFS display, shows a very short response time, and has a very good low temperature stability. Example 5

The following mixture (M-5) is prepared and investigated.

This mixture, mixture M-5, has a dielectric ratio (ε±/Δε) of 0.73, a ratio of (yi/kn) of 4.44 mPa s / pN and is characterized by a very good transmission in an FFS display, shows a very short response time, and has a very good low temperature stability. Example 6

The following mixture (M-6) is prepared and investigated.

Example 7

The following mixture (M-7) is prepared and investigated.

This mixture, mixture M-7, has a dielectric ratio (ε±/Δε) of 0.80, a ratio of (yi/kn) of 4.32 mPa s / pN and is characterized by a very good transmission in an FFS display, shows a very short response time, and has a very good low temperature stability. Example 8

The following mixture (M-8) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]This mixture, mixture M-8, is characterized by a good transmission in an FFS display, shows a short response time, and has a very good low temperature stability. Example 9

The following mixture (M-9) is prepared and investigated.

This mixture, mixture M-9, has is characterized by a very good transmission in an FFS display, shows a very short response time, and has a very good low temperature stability. Example 10

The following mixture (M-10) is prepared and investigated.

This mixture, mixture M-10, has a dielectric ratio (ε±/Δε) of 0.86, a ratio of (yi/kn) of 4.1 1 mPa s / pN and is characterized by a very good

transmission in an FFS display, shows a very short response time, and has a very good low temperature stability. Example 1 1

The following mixture (M-1 1 ) is prepared and investigated.

This mixture, mixture M-1 1 , has a dielectric ratio (ε±/Δε) of 0.77, a ratio of (yi/kn) of 4.17 mPa-s / pN and is characterized by a very good

transmission in an FFS display, shows a very short response time, and has a very good low temperature stability. Example 12

The following mixture (M-12 is prepared and investigated.

This mixture, mixture M-12, has a dielectric ratio (ε±/Δε) of 1 .26, a ratio of (yi/kn) of 4.97 mPa-s / pN and is characterized by a very good

transmission in an FFS display, shows a very short response time, and has a very good low temperature stability. Example 13

The following mixture (M-13) is prepared and investigated.

This mixture, mixture M-13, has a dielectric ratio (ε±/Δε) of 1 .09, a ratio of (yi/kn) of 5.0 mPa s / pN and is characterized by a very good transmission in an FFS display, shows a very short response time, and has a very good low temperature stability. Example 14

The following mixture (M-14) is prepared and investigated.

This mixture, mixture M-16, has a good dielectric ratio (ε±/Δε), a good ratio of (yi/kn) and is characterized by a very good transmission in an FFS display, shows a very short response time, and has a very good low temperature stability. Example 15

The following mixture (M-15) is prepared and investigated.

This mixture, mixture M-15, has a dielectric ratio (ε±/Δε) of 0.89, a ratio of (yi/kn) of 4.31 mPa s / pN and is characterized by a very good

transmission in an FFS display, shows a very short response time, and has a very good low temperature stability. Example 16

The following mixture (M-16) is prepared and investigated.

This mixture, mixture M-16, has has a dielectric ratio (ε±/Δε) of 0.93, a ratio of (yi/kn) of 4.36 mPa s / pN and is characterized by a very good transmission in an FFS display, shows a very short response time, and has a very good low temperature stability. Example 17

The following mixture (M-17) is prepared and investigated.

This mixture, mixture M-17, is characterized by a very good transmission in an FFS display, shows a very short response time, and has a good low temperature stability. Example 18

The following mixture (M-18) is prepared and investigated.

This mixture, mixture M-18, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 19

The following mixture (M-19) is prepared and investigated.

This mixture, mixture M-19, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 20

The following mixture (M-20) is prepared and investigated.

This mixture, mixture M-20, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 21

The following mixture (M-21 ) is prepared and investigated.

This mixture, mixture M-21 , is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 22

The following mixture (M-22) is prepared and investigated.

This mixture, mixture M-22, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 23

The following mixture (M-23) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-23, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 24

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN] This mixture, mixture M-24, is characterized by a very good transm in an FFS display and has a good low temperature stability.

Example 25

The following mixture (M-25) is prepared and investigated.

This mixture, mixture M-25, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 26

The following mixture (M-26) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-26, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 27

The following mixture (M-27) is prepared and investigated.

This mixture, mixture M-27, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 28

The following mixture (M-28) is prepared and investigated.

This mixture, mixture M-28, is characterized by a very good transm in an FFS display and has a good low temperature stability.

Example 29

The following mixture (M-29) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-29, is characterized by a very good transm in an FFS display and has a good low temperature stability.

Example 30

The following mixture (M-30) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN] This mixture, mixture M-30, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 31

(M-31 ) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN] This mixture, mixture M-31 , is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 32

The following mixture (M-32) is prepared and investigated.

This mixture, mixture M-32, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 33

The following mixture (M-33) is prepared and investigated.

This mixture, mixture M-33, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 34

The following mixture (M-34) is prepared and investigated.

This mixture, mixture M-34, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 35

The following mixture (M-35) is prepared and investigated.

This mixture, mixture M-35, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 36

The following mixture (M-36) is prepared and investigated.

This mixture, mixture M-36, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 37

The following mixture (M-37) is prepared and investigated.

This mixture, mixture M-37, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 38

The following mixture (M-38) is prepared and investigated.

This mixture, mixture M-38, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 39

The following mixture (M-39) is prepared and investigated.

This mixture, mixture M-39, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 40

The following mixture (M-40) is prepared and investigated.

This mixture, mixture M-40, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 41

The following mixture (M-41 ) is prepared and investigated.

This mixture, mixture M-41 , is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 42

The following mixture (M-42) is prepared and investigated.

This mixture, mixture M-42, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 43

The following mixture (M-43) is prepared and investigated.

This mixture, mixture M-43, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 44

The following mixture (M-44) is prepared and investigated.

This mixture, mixture M-44, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 45

The following mixture (M-45) is prepared and investigated.

This mixture, mixture M-45, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 46

The following mixture (M-46) is prepared and investigated.

This mixture, mixture M-46, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 47 -

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-47, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 48

The following mixture (M-48) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-48, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 49

The following mixture (M-49) is prepared and investigated.

This mixture, mixture M-49, is characterized by a very good transm in an FFS display and has a good low temperature stability.

Example 50

The following mixture (M-50) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-50, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 51 (MDA-17-2436)

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN] This mixture, mixture M-51 , is characterized by a very good transm in an FFS display and has a good low temperature stability.

Example 52

The following mixture (M-52) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-52, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 53

The following mixture (M-53) is prepared and investigated.

This mixture, mixture M-53, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 54

The following mixture (M-54) is prepared and investigated.

This mixture, mixture M-54, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 55

The following mixture (M-55) is prepared and investigated.

This mixture, mixture M-55, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 56

The following mixture (M-56) is prepared and investigated.

This mixture, mixture M-56, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 57

The following mixture (M-57) is prepared and investigated.

This mixture, mixture M-57, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 58

The following mixture (M-58) is prepared and investigated.

This mixture, mixture M-58, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 59

The following mixture (M-59) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-59, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 60

The following mixture (M-60) is prepared and investigated.

This mixture, mixture M-60, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 61

The following mixture (M-61 ) is prepared and investigated.

This mixture, mixture M-61 , is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 62

The following mixture (M-62) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-62, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 63

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-63, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 64

This mixture, mixture M-64, is characterized by a very good transm in an FFS display and has a good low temperature stability.

Example 65

The following mixture (M-65) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-65, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 66

The following mixture (M-66) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-66, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 67

The following mixture (M-67) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-67, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 68

The following mixture (M-68) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-68, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 69

The following mixture (M-69) is prepared and investigated.

This mixture, mixture M-69, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 70

The following mixture (M-70) is prepared and investigated.

This mixture, mixture M-70, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 71

The following mixture (M-71 ) is prepared and investigated.

This mixture, mixture M-71 , is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 72

The following mixture (M-72) is prepared and investigated.

This mixture, mixture M-72, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 73

The following mixture (M-73) is prepared and investigated.

This mixture, mixture M-73, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 74

The following mixture (M-74) is prepared and investigated.

This mixture, mixture M-74, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 75

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-75, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 76

The following mixture (M-76) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-76, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 77

This mixture, mixture M-77, is characterized by a very good transm in an FFS display and has a good low temperature stability.

Example 78

The following mixture (M-78) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-78, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 79

The following mixture (M-79) is prepared and investigated.

Remarks: t.b.d.: to be determined and ^*: [mPa s/pN]

This mixture, mixture M-79, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 80

The following mixture (M-80) is prepared and investigated.

This mixture, mixture M-80, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 81

The following mixture (M-81 ) is prepared and investigated.

This mixture, mixture M-81 , is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 82

The following mixture (M-82) is prepared and investigated.

This mixture, mixture M-82, is characterized by a very good transmission in an FFS display and has a good low temperature stability. Example 83

The following mixture (M-83) is prepared and investigated.

This mixture, mixture M-83, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 84

The following mixture (M-84) is prepared and investigated.

This mixture, mixture M-84, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 85

The following mixture (M-85) is prepared and investigated.

This mixture, mixture M-85, is characterized by a very good transm in an FFS display and has a good low temperature stability. Example 86

The following mixture (M-86) is prepared and investigated.

This mixture, mixture M-86, is characterized by a very good transm in an FFS display and has a good low temperature stability.

Claims

Patent Claims Liquid-crystalline medium having a nematic phase and a dielectric anisotropy (Δε) of 0.5 or more characterized in that it comprises one or more compounds of formula B

n denotes 1 or 2,

R¹ denotes alkyl, alkoxy, fluorinated alkyl, fluorinated alkoxy, alkenyl, alkenyloxy, alkoxyalkyi or fluorinated alkenyl and X¹ denotes F. CI. fluorinated alkyl. fluorinated alkenyl. fluohnated alkoxy or fluorinated alkenlyoxy.

Medium according to Claim 1 , characterized in that it comprises one or more compounds of formula B, which are selected from the group of compounds of formulae B-1 and B-2

which the parameters have the respective meanings given in claim 1

Medium according to Claim 1 or 2, characterized in that it additionally comprises one or more compounds of formula I:

in which

independently of each other denote alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, alkenyl, alkenyloxy, alkoxyalkyi or fluorinated alkenyl having 2 to 7 C atoms and R¹¹ alternatively denotes R¹ and R¹² alternatively denotes X¹,

R¹ denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyi or fluorinated alkenyl having 2 to 7 C atoms and preferably alkyl or alkenyl, and

X¹ denotes F, CI, fluorinated alkyl, fluorinated alkenyl, fluorinated alkoxy or fluorinated alkenyloxy, from which the compounds of formula B are excluded.

4. Medium according to at least one of Claims 1 to 3, characterized in that it comprises one or more compounds selected from the group of compounds of formulae II and III.

in which

R² denotes alkyi, alkoxy, fluorinated alkyi or fluorinated alkoxy having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyi or fluorinated alkenyl having 2 to 7 C atoms,

on each appearance, independently of one another, denote

denote H or F, denotes halogen, halogenated alkyl or alkoxy having 1 to 3 C atoms or halogenated alkenyl or alkenyloxy having 2 or 3 C atoms, denotes 0, 1 , 2 or 3, denotes alkyl, alkoxy, fluorinated alkyl or fluorinated

alkoxy having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyi or fluorinated alkenyl having 2 to 7 C atoms

on each a earance, independently of one another, are

L³¹ and L³², independently of one another, denote H or F, X³ denotes halogen, halogenated alkyl or alkoxy having 1 to 3 C atoms or halogenated alkenyl or alkenyloxy having 2 or 3 C atoms, F, CI, -OCF₃, -OCHF₂,

-O-CH2CF3, -O-CH=CF₂, -O-CH=CH₂ or -CF₃, denotes -CH2CH2-, -CF2CF2-, -COO-, tran-sCH=CH-, trans -CF=CF-, -CH2O- or a single bond, and denotes 0, 1 , 2 or 3.

5. Liquid-crystalline medium according to at least one of Claims 1 to 4, characterized in that it comprises one or more dielectrically neutral compounds selected from the group of formulae IV and V:

in which R⁴¹ and R⁴², independently of one another, have the meaning indicated in claim 4 for R² under formula II,

independently of one another and, if occurs twice,

also these independently of one another, denote

denote -CH₂CH₂-, -COO-, trans-CH=CH-, trans- CF=CF-, -CH2O-, -CF2O-, -C≡C- or a single bond, p denotes 0, 1 or 2,

R⁵¹ and R⁵², independently of one another, have one of the meanings given for R⁴¹ and R⁴²

if resent, each, inde endentl of one another, denote

_Z51 _{t0 Z}53 each, independently of one another, denote

-CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, and each, independently of one another, denote 0 or 1 .

6. Liquid-crystalline medium according to Claim 5, characterized in that it comprises one or more compounds selected from the group of formulae VI to IX:

denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkenyl radical having 2 to 7 C atoms, an unsubstituted alkoxy radical having 1 to 6 C atoms or an unsubstituted alkenyloxy radical having 2 to 6 C atoms, denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkoxy radical having 1 to 6 C atoms or an unsubstituted alkenyloxy radical having 2 to 6 C atoms, and denotes 0 or 1 , denotes an unsubstituted alkyl radical having 1 to 7 C atoms, or an unsubstituted alkenyl radical having 2 to 7 C atoms, denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkoxy radical having 1 to 6 C atoms or an unsubstituted alkenyloxy radical having 2 to 6 C atoms,

denotes an unsubstituted alkyl radical having 1 to 7 C atoms, or an unsubstituted alkenyl radical having 2 to 7 C atoms, denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkoxy radical having 1 to 6 C atoms or an unsubstituted alkenyloxy radical having 2 to 6 C atoms, preferably having 2, 3 or 4 C atoms,

Z⁸ denotes -(C=O)-O-, -CH₂-O-, -CF₂-O- or -CH₂-CH₂-, o denotes 0 or 1 ,

p and q independently of each other denote 0 or 1 , and

7. Medium according to at least one of Claims 1 to 6, characterized in that the total concentration of the compounds of formula B in the medium as a whole is 1 % or more to 60 % or less.

Medium according to at least one of Claims 1 to 7, characterized in that it additionally comprises one or more chiral compounds and/or stabilizers.

9. Electro-optical display or electro-optical component, characterized in that it comprises a liquid-crystalline medium according to at least one of Claims 1 to 8.

10. Display according to Clainn 9, characterized in that it is based on the IPS- or FFS mode.

1 1 Display according to Claim 9 or 10, characterized in that it contains an active-matrix addressing device.

12. Use of a medium according to at least one of Claims 1 to 8 in an electro-optical display or in an electro-optical component.

13. Process for the preparation of a liquid-crystalline medium according to one or more of Claims 1 to 8, characterized in that one or more compounds of formula B are mixed with one or more additional mesogenic compounds and optionally one or more additives.

14. Compound of formula B

in which the other parameters have the respective meanings given under formula B in claim 1 .

15. Process for the preparation of a compound of formula B as given in claim 14, characterized in that it comprises a step in which a fluorinated biphenol compound (compound 3 according to synthesis scheme 1 ) is converted into a fluorinated dibenzofuran compound (compound 4 according to synthesis scheme 1 ).