DE102015013980A1 - Heterocyclic compound, liquid-crystalline medium, method for its stabilization and liquid crystal display - Google Patents

Abstract

The invention relates to a liquid crystal (FK) display comprising an FK cell consisting of two substrates, wherein at least one substrate is translucent and at least one substrate has a planar orientation layer and control electrodes, and a layer of FK medium between the substrates with negative dielectric anisotropy, characterized in that the LC display contains a compound of the formula, and optionally a) one or more compounds of the formula II and / or b) one or more compounds selected from the group of the compounds of the formulas III and IV, wherein the Parameters having the respective meanings given in claim 1, as well as the use of the compounds of formula I, for stabilizing a liquid-crystalline medium containing one or more compounds of the formulas II and / or III and / or IV.

Description

The present invention relates, inter alia, to novel compounds, in particular for use in liquid-crystal media, but also to the use of these liquid-crystal media in liquid-crystal displays, and to these liquid-crystal displays, especially liquid crystal displays, which employ IPS (in-plane switching) or FFS (fringe field-switching) with dielectrically negative Use liquid crystals in a homogeneous (planar) orientation orientation. The liquid-crystal media according to the invention are comparatively stable against thermal and UV exposure and show reduced burn-in behavior (English "image stcking.") They are also distinguished by a particularly low switching time in the displays according to the invention with simultaneously high voltage holding capacity (English: "voltage holding ratio") VHR or even HR).

The IPS principle is z. In DE 40 00 451 for both liquid crystals with positive and liquid crystals with negative dielectric anisotropy. Here, the Umorioentierung the liquid crystals (in the plane: "in plan") is achieved by the application of an electric field having an essential component in the plane of the liquid crystal layer. In this case, the two structured electrodes of a single display element are typically arranged on the one side of the liquid crystal layer and interlocked with one another (for example, so-called interdigitated "interdigital electrodes"). For FFS ads, such as In Lee, SH, Lee, SL, and Kim, H.Y. Appl. Phys. Lett. 73 (20), pp. 2881-2883, 1998 ) is one of these electrodes, typically the one facing away from the liquid crystal layer, continuous while the other electrode is patterned.

For the technical application of this effect in electro-optical display elements FK phases are needed, which must meet a variety of requirements. Particularly important here are the chemical resistance to moisture, air and physical influences such as heat, radiation in the infrared, visible and ultraviolet range and electrical DC and AC fields.

Furthermore, technically usable LC phases require a liquid-crystalline mesophase in a suitable temperature range and a low viscosity.

In none of the previously known series of compounds with liquid-crystalline mesophase there is a single compound that meets all these requirements. As a rule, mixtures of two to 25, preferably three to 18, compounds are therefore prepared in order to obtain substances which can be used as LC phases.

Matrix liquid crystal displays (MFK displays) are known. For example, active elements (i.e., transistors) may be used as nonlinear elements for individual switching of the individual pixels. This is referred to as an "active matrix", generally using thin-film transistors (TFT), which are usually arranged on a glass plate as a substrate.

A distinction is made between two technologies: TFTs made of compound semiconductors such as. B. CdSe or TFT's based on polycrystalline and u. a. amorphous silicon. The latter technology currently has the greatest commercial significance worldwide.

The TFT matrix is applied on the inside of one glass plate of the display, while the other glass plate on the inside carries the transparent counter electrode. Compared to the size of the pixel electrode, the TFT is very small and practically does not disturb the image. This technology can also be extended to fully color-capable image representations, wherein a mosaic of red, green and blue filters is arranged such that each one filter element is opposite to a switchable image element.

The most commonly used TFT displays commonly use crossed polarizers in transmission and are backlit. For TV applications, IPS cells or ECB (or VAN) cells are used, whereas for monitors mostly IPS cells or TN (twisted nematic) cells and for note books, lap tops and mobile applications are used TN cells are used.

The term MFK displays here includes any matrix display with integrated non-linear elements, ie. H. in addition to the active matrix also displays with passive elements such as varistors or diodes (MIM = metal-insulator-metal).

Such MFK displays are particularly suitable for TV applications, monitors and "note books" or displays with high information density z. B. in automotive or aircraft. Besides problems With regard to the angular dependence of the contrast and the switching times, difficulties arise in the case of MFK displays due to the insufficiently high specific resistance of the liquid-crystal mixtures [ TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K., TAJIMA, E., WATANABE, H., SHIMIZU, H., Proc. Eurodisplay 84, Sept. 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, p. 141 ff, Paris ; STROMER, M., Proc. Eurodisplay 84, Sept. 1984: Design of Thin Film Transistors for Matrix Liquid Crystal Displays, p. 145 ff, Paris ]. As the resistance decreases, the contrast of a MFK display degrades. Since the resistivity of the liquid crystal mixture generally decreases over the life of a MFK display due to interaction with the internal surfaces of the display, high (initial) resistance is very important for displays that must have acceptable resistance values over a long period of operation.

Ads that use the IPS (for example: Yeo, SD, Lecture 15.3: "A LC Display for the TV Application," SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp. 758 and 759 ) and FFS effect have established themselves, besides ECB displays in their various embodiments and the long known TN displays, as one of the three most important recent types of liquid crystal displays, especially for television applications. This is especially true in portable devices, such as smartphones and tablet computers, which require the best possible (ie low) viewing angle dependency of the displays, in combination with the possibility of interaction via the touchscreen. Especially with regard to the input via the touch screen, IPS or FFS displays are clearly superior to the other types of display, since the electro-optical effect depends on the thickness of the equipment to a minimum.

IPS / FFS displays according to the present application, such as ECB, VA (such as MVA, PVA and PS-VA) and ASV displays use liquid-crystalline media with negative dielectric anisotropy (Δε), whereas TN- and previously popular IPS and FFS displays use liquid crystalline media with positive dielectric anisotropy.

In all such liquid crystal displays, the liquid crystals are used as dielectrics whose optical properties reversibly change upon application of an electrical voltage.

Since in displays in general, including ads for these effects mentioned, the operating voltage should be as low as possible, liquid crystal media are used, which are usually composed predominantly of liquid crystal compounds, all of which have the same sign of dielectric anisotropy and the largest possible amount have the dielectric anisotropy. As a rule, at most lower proportions of neutral compounds and as far as possible no compounds with a sign of the dielectric anisotropy, which is opposite to that of the medium, are used. In the case of liquid dielectric media with negative dielectric anisotropy for IPS or FFS displays, predominantly compounds with negative dielectric anisotropy are used. As a rule, the liquid-crystal media used predominantly and mostly even consist largely of liquid-crystal compounds with negative dielectric anisotropy.

In the media used according to the present application are typically at most significant amounts of dielectrically neutral liquid crystal compounds and usually only very small amounts of or no dielectrically positive compounds used, since generally the liquid crystal displays should have the lowest possible drive voltages.

bzw. der Formeln

enthalten. Diese Mischungen weisen jedoch Eigenschaften auf, die für viele anspruchsvolle Anwendungen keinesfalls ausreichen. Auch werden keine Stabilisatoren in diesen Mischungen verwendet.In DE 10 2008 006 875 A1 Liquid crystal mixtures are disclosed which contain the alkenyl compounds of the formulas

or the formulas

contain. However, these blends have properties that are by no means sufficient for many demanding applications. Also, no stabilizers are used in these mixtures.

zur Verwendung in Flüssigkristallmischungen. Die Flüssigkristallmischungen dieser Schrift sollen jedoch zur Verhinderung einer Verschlechterung der Eigenschaften durch die Bestrahlung mit einer Hintergrundbeleuchtung in einer Anzeige, mit einem Kantenfilter in der Hintergrundbeleuchtung betrieben werden. Für viele praktische Anwendungen in Flüssigkristallanzeigen sind die bekannten Flüssigkristallmedien jedoch nicht stabil genug. Insbesondere ihre Stabilität gegen die Bestrahlung mit UV, aber auch bereits mit den üblichen Hintergrundbeleuchtungen führt zu einer Verschlechterung insbesondere der elektrischen Eigenschaften. So nimmt z. B. die Leitfähigkeit signifikant zu. DE 10 2011 008 687 A1 mentions, among many other compounds, alkenyl compounds of the formulas

for use in liquid crystal mixtures. However, the liquid crystal mixtures of this document are intended to prevent deterioration of the properties by the irradiation with a Backlight in a display, operated with an edge filter in the backlight. However, for many practical applications in liquid crystal displays, the known liquid crystal media are not stable enough. In particular, their stability against the irradiation with UV, but also already with the usual backlighting leads to a deterioration in particular of the electrical properties. So z. As the conductivity significantly.

For the stabilization of liquid-crystal mixtures, the use of so-called "hindered amine light stabilizers", HALS for short, has already been proposed.

Similar liquid crystal mixtures are z. B. also off EP 2 182 046 A1 . WO 2008/009417 A1 . WO 2009/021671 A1 and WO 2009/115186 A1 known. However, there is no mention of the use of stabilizers.

These liquid crystal mixtures can optionally according to the disclosure there also stabilizers of various types, such as. As phenols and hindered amines (English: hindered amine light stabilizers, short: HALS) included. However, the above unstabilized liquid crystal mixtures are characterized by relatively high threshold voltages and, at best, moderate stabilities. In particular, their "Voltage Holding Ratio" decreases after exposure. In addition, often yellowish discoloration occurs.

The use of various stabilizers in liquid-crystalline media is z. In JP (S) 55-023169 (A) . JP (H) 05-117324 (A) . WO 02/18515 A1 and JP (H) 09-291282 (A) described.

Bis (2,2,6,6-tetraethyl-4-piperindinyl) sebacetate is made WO 94/07489 A1 known.

The liquid crystal media of the prior art with correspondingly low drive voltages have relatively low electrical resistances or a low HR and often result in undesirable "flicker" and / or unwanted image sticking effects in the displays. In addition, they are not sufficiently stable against temperature and / or UV exposure, at least when they have a correspondingly high polarity, as is necessary for low drive voltages.

On the other hand, the drive voltage of the prior art displays, which have a very high HR, often too large, especially for displays that are not connected directly or not continuously to the power supply network such. B. Ads for mobile applications such. B. mobile phones, smarphones, tablet PC u. s. w ..

In addition, the phase range of the liquid crystal mixture must be sufficiently wide for the intended application of the display.

The switching times of the liquid crystal media in the displays must be improved, ie reduced. This is especially important for ads for TV or multi-media applications. To improve the switching times, it has repeatedly been proposed in the past to optimize the rotational viscosity of the liquid-crystal media (γ ₁ ), ie to realize media with the lowest possible rotational viscosity. However, the results obtained are not sufficient for many applications and therefore make it desirable to find further optimization approaches.

Especially important is a sufficient stability of the media against extreme loads, especially against UV and temperature stress. Especially for applications in ads in mobile devices such. As mobile phones, this can be crucial.

The disadvantage of the previously known MFK displays is based on their comparatively low contrast, the relatively high viewing angle dependence and the difficulty in these displays gray levels, and their insufficient HR and their insufficient life.

Thus, there is still a great need for MFK displays with very high resistivity coupled with a large operating temperature range, short switching times and low threshold voltage, which can be used to produce different levels of gray and which also have relatively good and stable HR.

The invention is based on the object MFK displays, not only for monitor and TV applications, but also for mobile phones and navigation systems, which are based on the IPS or FFS effect, to provide that have the disadvantages mentioned above, or only to a lesser extent and at the same time very high resistivities. In particular, it must be ensured for mobile phones and navigation systems that they work even at extremely high and extremely low temperatures.

Surprisingly, it has been found that liquid crystal displays can be realized which, in particular in IPS or FFS displays which have at least one planar orientation layer, have a low threshold voltage with short switching times and at the same time have a sufficiently broad nematic phase, a favorable, relatively low birefringence (Δn ), good stability against decomposition by thermal and UV exposure and a stable high HR, if one uses in these display elements nematic liquid crystal mixtures with negative dielectric anisotropy, the compound of the formula I and a compound of formula II, and in each case at least one A compound of the formula III or IV, preferably selected from the group of compounds of the sub-formulas III-1 to III-7, and preferably selected from the group of the compounds of the formulas IV-1 to IV-4, and optionally, preferably compulsorily, at least selected a connection LDS from the group of compounds of formulas V and VI.

Such electro-optical displays with active matrix addressing based on the IPS and the FFS effect are particularly suitable for TV and monitor applications as well as for mobile phones and tablet computers.

The invention thus relates to a liquid crystal (FK) display comprising an FK cell consisting of two substrates, wherein at least one substrate is translucent and at least one substrate has a planar orientation layer and control electrodes, and a layer of an FK layer located between the substrates. Medium having negative dielectric anisotropy, characterized in that the LC display contains a compound of the formula I and preferably additionally contains one or more compounds selected from the group of the compounds of the formulas II, III and IV.

The FK medium in the displays according to the invention show very broad nematic phase ranges with clearing points ≥ 70 ° C., very favorable values for the capacitive 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. Furthermore, the FK medium is characterized by a good ratio of clearing point and rotational viscosity and by a high negative dielectric anisotropy.

Surprisingly, it has now been found that LC displays containing liquid-crystalline media having a suitably high Δε, a suitable phase range and Δn can be realized which do not have the disadvantages of the materials of the prior art or at least only to a considerably lesser extent.

It has surprisingly been found here that the use of the compounds of the formula I, even if used alone without additional temperature stabilizers in the LC displays according to the invention, leads to a considerable, in many cases sufficient, stabilization of liquid-crystal mixtures both against UV exposure and lead to temperature stress.

However, adequate stabilization of liquid-crystal mixtures both against UV exposure and against temperature stress can also be achieved in particular when, in addition to the compound of the formula I, one or more further compounds, preferably phenolic stabilizers, are used in the LC display. These further compounds are suitable as stabilizers against thermal stress.

worin
I eine ganze Zahl von 2 bis 26 ist.
in FK-Anzeigen des IPS-(in plane switching) oder FFS-(fringe field switching) oder Polymer Stabilized(PS)-IPS- oder PS-FFS Typs.The invention thus relates to the use of compounds of the formula I:

wherein
I is an integer from 2 to 26.
in FK displays of IPS (in-plane switching) or FFS (fringe field switching) or Polymer Stabilized (PS) -IPS or PS-FFS type.

• a) eine Verbindung der Formel II
  
  R²¹ einen unsubstituierten Alkylrest mit 1 bis 5 C-Atomen, oder einen unsubstituierten Alkenylrest mit 2 bis 5 C-Atomen, R²² einen unsubstituierten Alkenylrest mit 2 bis 5 C-Atomen, in einer Konzentration von ≥ 20%, bevorzugt ≥ 25%, besonders bevorzugt ≥ 30%,
• b) eine oder mehrere Verbindungen ausgewählt aus der Gruppe der Verbindungen der Formeln III und IV:
  
  worin unabhängig voneinander R³¹ einen unsubstituierten Alkylrest mit 1 bis 7 C-Atomen, einen unsubstituierten Alkyloxyrest mit 1 bis 7 C-Atomen oder einen unsubstituierten Alkenylrest mit 2 bis 7 C-Atomen, oder einen unsubstituierten Cycloalkylrest mit 3 bis 7 C-Atomen, R³² einen unsubstituierten Alkylrest mit 1 bis 7 C-Atomen, einen unsubstituierten Alkyloxyrest mit 1 bis 7 C-Atomen oder einen unsubstituierten Alkenylrest mit 2 bis 7 C-Atomen, R⁴¹ einen unsubstituierten Alkylrest mit 1 bis 7 C-Atomen oder einen unsubstituierten Alkenylrest mit 2 bis 7 C-Atomen, R⁴² einen unsubstituierten Alkylrest mit 1 bis 7 C-Atomen, einen unsubstituierten Alkyloxyrest mit 1 bis 7 C-Atomen oder einen unsubstituierten Alkenylrest mit 2 bis 7 C-Atomen,
  
  und
  
  bei jedem Auftreten unabhängig voneinander
  
  
  bei jedem Auftreten unabhängig voneinander
  
  
  einer von Z⁴¹ und Z⁴² -CH₂-CH₂-, -CH=CH-, -CH₂-O-, -O-CH₂-, -CF₂-O- oder -O-CF₂- und der andere -CH₂-CH₂-, -CH=CH-, -CH₂-O-, -O-CH₂-, -CF₂-O-, -O-CF₂- oder eine Einfachbindung, m und n jeweils unabhängig voneinander 0, 1 oder 2, (m + n) 0, 1, 2, oder 3, p und q jeweils unabhängig voneinander 0, 1 oder 2, und (p + q) 1, 2, oder 3, bedeuten,
• c) eine oder mehrere Verbindungen ausgewählt aus der Gruppe der Verbindungen der Formeln V oder der Formel VI,
  
  worin R⁵¹ und R⁵² unabhängig voneinander eine der für R³¹ und R³² gegebenen Bedeutung haben und bevorzugt Alkyl mit 1 bis 7 C-Atomen, bevorzugt n-Alkyl, besonders bevorzugt n-Alkyl mit 1 bis 5 C-Atomen, Alkoxy mit 1 bis 7 C-Atomen, bevorzugt n-Alkoxy, besonders bevorzugt n-Alkoxy mit 2 bis 5 C-Atomen, Alkoxyalkyl, Alkenyl oder Alkenyloxy mit 2 bis 7 C-Atomen, bevorzugt mit 2 bis 4 C-Atomen, bevorzugt Alkenyloxy,
  
  bis
  
  soweit vorhanden, jeweils unabhängig voneinander
  
  bevorzugt
  
  bevorzugt
  
  und, wenn vorhanden,
  
  Z⁵¹ bis Z⁵³ jeweils unabhängig voneinander -CH₂-CH₂-, -CH₂-O-, -CH=CH-, -C≡C-, -COO- oder eine Einfachbindung, bevorzugt -CH₂-CH₂-, -CH₂-O- oder eine Einfachbindung und besonders bevorzugt eine Einfachbindung, i und j jeweils unabhängig voneinander 0 oder 1, (i + j) bevorzugt 0 oder 1, R⁶¹ einen unsubstituierten Alkylrest mit 1 bis 7 C-Atomen oder bevorzugt einen n-Alkylrest, besonders bevorzugt mit 2, 3, 4 oder 5 C-Atomen, und R⁶² einen unsubstituierten Alkylrest mit 1 bis 7 C-Atomen oder einen unsubstituierten Alkoxyrest mit 1 bis 6 C-Atomen, beide bevorzugt mit 2 bis 5 C-Atomen bedeuten, enthält.

In particular, the use of compounds of the formula I in abovementioned FK displays comprising a liquid-crystalline medium having a nematic phase and a negative dielectric anisotropy of ≦ -3.5 to ≥ -6, which

• a) a compound of formula II
  
  R ^{21 is} an unsubstituted alkyl radical having 1 to 5 C atoms, or an unsubstituted alkenyl radical having 2 to 5 C atoms, R ^{22 is} an unsubstituted alkenyl radical having 2 to 5 C atoms, in a concentration of ≥ 20%, preferably ≥ 25% , particularly preferably ≥ 30%,
• b) one or more compounds selected from the group of the compounds of the formulas III and IV:
  
  in which independently of one another R ^{31 is} an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkyloxy radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, or an unsubstituted cycloalkyl radical having 3 to 7 C atoms, R ^{32 is} an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkyloxy radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, R ^{41 is} an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted Alkenyl radical having 2 to 7 C atoms, R ⁴² denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkyloxy radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms,
  
  and
  
  independent on each occurrence
  
  
  independent on each occurrence
  
  
  one of Z ⁴¹ and Z ^{42 is} -CH ₂ -CH ₂ -, -CH = CH-, -CH ₂ -O-, -O-CH ₂ -, -CF ₂ -O- or -O-CF ₂ - and the others -CH ₂ -CH ₂ -, -CH = CH-, -CH ₂ -O-, -O-CH ₂ -, -CF ₂ -O-, -O-CF ₂ - or a single bond, m and n each independently 0, 1 or 2, (m + n) 0, 1, 2, or 3, p and q are each independently 0, 1 or 2, and (p + q) 1, 2, or 3,
• c) one or more compounds selected from the group of the compounds of the formulas V or of the formula VI,
  
  wherein R ⁵¹ and R ⁵² independently of one another have the meaning given for R ³¹ and R ³² , and preferably alkyl having 1 to 7 C atoms, preferably n-alkyl, particularly preferably n-alkyl having 1 to 5 C atoms, alkoxy with 1 to 7 C atoms, preferably n-alkoxy, particularly preferably n-alkoxy having 2 to 5 C atoms, alkoxyalkyl, alkenyl or alkenyloxy having 2 to 7 C atoms, preferably having 2 to 4 C atoms, preferably alkenyloxy,
  
  to
  
  if available, each independently
  
  prefers
  
  prefers
  
  and, if available,
  
  Z ⁵¹ to Z ^{53 are} each independently of one another -CH ₂ -CH ₂ -, -CH ₂ -O-, -CH = CH-, -C≡C-, -COO- or a single bond, preferably -CH ₂ -CH ₂ - , -CH ₂ -O- or a single bond and particularly preferably a single bond, i and j are each independently 0 or 1, (i + j) preferably 0 or 1, R ^{61 is} an unsubstituted alkyl radical having 1 to 7 carbon atoms or preferred an n-alkyl radical, particularly preferably having 2, 3, 4 or 5 C atoms, and R ^{62 is} an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms, both preferably having 2 to 5 C atoms mean, contains.

The compound of the formula I are preferably used in a concentration in the range from 1 ppm to 2,000 ppm, preferably up to 1,000 ppm, more preferably in the range from 300 ppm to 1000 ppm.

Preferred compounds of the formula I have a parameter I which defines the length of the alkyl chain which is between 2 and 26 (I = 2-26), preferably between 6 and 22, particularly preferably between 8 and 20. Very particular preference is given to the compounds of the formula I which have an even number of CH ₂ groups in the chain. These preferred compounds have a CH ₂ chain length which ensures good solubility of the compounds of formula I in the LC mixtures of this invention. If the chain length is too short (I <6), the solubility may be limited depending on the LC mixture and result in insufficient stability at low temperatures (LTS). If the chain length is too long (I> 22), the coupling of the two end groups becomes weaker. This leads to a behavior similar to the stabilizers with only one HALS group (mono-HALS), which do not effectively stabilize liquid crystal mixtures.

In a preferred embodiment of the present invention displays, the present invention each contain one or more compounds of the formula I selected from the group of the following compounds of the formulas I-1 to I-8, of Which I-2 is therefore known as TINUVIN 770 ^® :

Preferably, the LC medium according to the present inventive LC display, in addition to the compounds of the formula I, or their preferred sub-formulas, contain one or more dielectrically neutral compounds of the formula II in a total concentration in the range of 15% or more to 70% or less, preferably from 20% or more to 60% or less, more preferably from 25% or more to 55% or less.

worin
R²¹ einen unsubstituierten Alkylrest mit 1 bis 7 C-Atomen oder einen unsubstituierten Alkenylrest mit 2 bis 7 C-Atomen, bevorzugt einen n-Alkylrest, besonders bevorzugt mit 2, 3, 4 oder 5 C-Atomen, und
R²² einen unsubstituierten Alkenylrest mit 2 bis 7 C-Atomen
bedeuten.In a further preferred embodiment, the medium contains one or more compounds of the formula II

wherein
R ^{21 is} 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, more preferably having 2, 3, 4 or 5 C atoms, and
R ^{22 is} an unsubstituted alkenyl radical having 2 to 7 carbon atoms
mean.

The medium according to the invention particularly preferably contains
one or more compounds of formula II in a total concentration in the range of 5% or more to 40% or less, preferably in the range of 10% or more to 25% or less, and / or
one or more compounds of formula II in a total concentration in the range of 10% or more to 60% or less, preferably in the range of 25% or more to 55% or less, more preferably in the range of 30% or more to 50% or less, most preferably in the range of 30% or more to 50% or less.

worin
Alkyl unabhängig voneinander Alkyl mit 1 bis 5 C-Atomen, bevorzugt mit 2 bis 5 C-Atomen,
Alkenyl einen Alkenylrest mit 2 bis 5 C-Atomen, bevorzugt mit 2 bis 4 C-Atomen, besonders bevorzugt 2 C-Atomen,
bedeuten.In a particularly preferred embodiment, the medium contains one or more compounds of the formula II selected from the group of the compounds of the formulas II-1 and II-2, preferably selected from the group of the compounds of the formulas II-1a to II-2b (see below),

wherein
Alkyl independently of one another alkyl having 1 to 5 C atoms, preferably having 2 to 5 C atoms,
Alkenyl is an alkenyl radical having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably 2 C atoms,
mean.

In a particularly preferred embodiment, the media according to the invention comprise one or more compounds of the formula II-1 and / or one or more compounds of the formula II-2, very particularly preferably one or more compounds of the formula II-1 and formula II-2 selected from the group of compounds of the following formulas

The media according to the invention preferably contain the following compounds in the indicated total concentrations
5-60% by weight of one or more compounds selected from the group of the compounds of the formula II and / or
10-60% by weight of one or more compounds selected from the group of the compounds of the formulas III-1 to III-8 and / or
10-60% by weight of one or more compounds of the formulas IV and / or V,
wherein the total content of all compounds in the medium is 100%.

Preferably, the FK medium according to the present inventive LC display, in addition to the compounds of the formula I, or their preferred sub-formulas, contain one or more dielectrically negative compounds of the formula III in a total concentration in the range of 5% or more to 90% or less, preferably from 10% or more to 80% or less, more preferably from 20% or more to 70% or less.

worin die Parameter die jeweiligen oben bei Formel III gegebenen Bedeutungen haben, und bevorzugt
R³¹ einen unsubstituierten Alkylrest mit 1 bis 7 C-Atomen, bevorzugt einen n-Alkylrest, besonders bevorzugt mit 2 bis 5 C-Atomen, oder
Alkyl oder Alkenyl, bevorzugt Ethyl, Propoyl, Butyl, Pentyl, Vinyl, 1-E-Propenyl, But-4-en-1-yl, Pent-1-en-1-yl oder Pent-3-en-1-yl und
R³² einen unsubstituierten Alkylrest mit 1 bis 7 C-Atomen, bevorzugt mit 2 bis 5 C-Atomen oder einen unsubstituierten Alkoxyrest mit 1 bis 6 C-Atomen, bevorzugt mit 2, 3 oder 4 C-Atomen, und
m, n und 0 jeweils unabhängig voneinander 0 oder 1,
bedeuten.In a preferred embodiment of the present invention, the media according to the invention each contain one or more compounds of the formula II selected from the group of the compounds of the formulas III-1 to III-7

wherein the parameters have the respective meanings given above for formula III, and preferred
R ^{31 is} an unsubstituted alkyl radical having 1 to 7 C atoms, preferably an n-alkyl radical, particularly preferably having 2 to 5 C atoms, or
Alkyl or alkenyl, preferably ethyl, propoyl, butyl, pentyl, vinyl, 1-E-propenyl, but-4-en-1-yl, pent-1-en-1-yl or pent-3-en-1-yl and
R ^{32 is} an unsubstituted alkyl radical having 1 to 7 C atoms, preferably having 2 to 5 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms, preferably having 2, 3 or 4 C atoms, and
m, n and 0 are each independently 0 or 1,
mean.

In a preferred embodiment of the present invention, the media according to the invention each contain one or more compounds of the formula III-1 and III-2 selected from the group of the following compounds

In a preferred embodiment of the present invention, the media according to the invention each contain one or more compounds of the formula III-3 selected from the group of the following compounds

In a preferred embodiment of the present invention, the media according to the invention each contain one or more compounds of the formula III-4 selected from the group of the following compounds

In a preferred embodiment of the present invention, the media according to the invention each contain one or more compounds of the formula III-5 selected from the group of the following compounds

In a preferred embodiment of the present invention, the media according to the invention each contain one or more compounds of the formula III-6 selected from the group of the following compounds

In a preferred embodiment of the present invention, the media according to the invention each contain one or more compounds of the formula III-7 selected from the group of the following compounds

Preferably, the medium according to the invention contains one or more compounds selected from the group of the formulas III-1 to III-7 in a total concentration in the range from 5% or more to 80% or less, preferably from 15% or more to 70% or less, more preferably from 20% or more to 60% or less.

worin die Parameter die jeweiligen oben bei Formel IV gegebenen Bedeutungen haben, und bevorzugt
R⁴¹ Alkyl mit 1 bis 7 C-Atomen oder Alkenyl mit 2 bis 7 C-Atomen, bevorzugt Ethyl, Propoyl, Butyl, Pentyl, Vinyl, 1-E-Propenyl, But-4-en-1-yl, Pent-1-en-1-yl oder Pent-3-en-1-yl und
R⁴² einen unsubstituierten Alkylrest mit 1 bis 7 C-Atomen, bevorzugt mit 2 bis 5 C-Atomen oder, bevorzugt, einen unsubstituierten Alkoxyrest mit 1 bis 6 C-Atomen, besonders bevorzugt mit 2 oder 4 C-Atomen,
bedeuten. In a preferred embodiment of the present invention, the media according to the invention each contain one or more compounds of the formula IV selected from the group of the compounds of the formulas IV-1 to IV-4,

wherein the parameters have the respective meanings given above for formula IV, and preferred
R ^{41 is} alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms, preferably ethyl, propoyl, butyl, pentyl, vinyl, 1-E-propenyl, but-4-en-1-yl, pent-1 -en-1-yl or pent-3-en-1-yl and
R ^{42 is} 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,
mean.

In a preferred embodiment of the present invention, the media according to the invention each contain one or more compounds of formula IV-1 to IV-4 selected from the group of the following compounds

The medium according to the invention particularly preferably contains
one or more compounds of formula III in a total concentration in the range of 5% or more to 80% or less, preferably in the range of 10% or more to 70% or less, more preferably in the range of 20% or more to 60% or less, and / or
one or more compounds of formula III-1 in a total concentration in the range of 1% or more to 20% or less, preferably in the range of 5% or more to 10% or less and / or
one or more compounds of formula III-2 in a total concentration in the range of 1% or more to 30% or less, preferably in the range of 3% or more to 20% or less, and / or
one or more compounds of formula III-3 in a total concentration in the range of 1% or more to 30% or less, preferably in the range of 3% or more to 20% or less
one or more compounds of formula III-4 in a total concentration in the range of 1% or more to 25% or less, preferably in the range of 5% or more to 20% or less and / or
one or more compounds of formula III-5 in a total concentration in the range of 1% or more to 20% or less, preferably in the range of 5% or more to 10% or less and / or
one or more compounds of formula III-6 in a total concentration in the range of 1% or more to 30% or less, preferably in the range of 10% or more to 25% or less and / or
one or more compounds of formula III-7 in a total concentration in the range of 1% or more to 20% or less, preferably in the range of 5% or more to 15% or less.

The medium according to the invention particularly preferably contains
one or more compounds of formula IV in a total concentration in the range of 5% or more to 70% or less, preferably in the range of 10% or more to 60% or less, more preferably in the range of 20% or more to 55% or less, and / or
one or more compounds of formula IV-1 in a total concentration ranging from 2% or more to 15% or less and / or
one or more compounds of formula IV-2 in a total concentration ranging from 3% or more to 20% or less and / or
one or more compounds of formula IV-3 in a total concentration ranging from 2% or more to 20% or less and / or
one or more compounds of formula IV-4 in a total concentration ranging from 3% or more to 25% or less and / or

worin
R⁵¹ und R⁵² unabhängig voneinander eine der für R²¹ und R²² gegebenen Bedeutung haben und bevorzugt Alkyl mit 1 bis 7 C-Atomen, bevorzugt n-Alkyl, besonders bevorzugt n-Alkyl mit 1 bis 5 C-Atomen, Alkoxy mit 1 bis 7 C-Atomen, bevorzugt n-Alkoxy, besonders bevorzugt n-Alkoxy mit 2 bis 5 C-Atomen, Alkoxyalkyl, Alkenyl oder Alkenyloxy mit 2 bis 7 C-Atomen, bevorzugt mit 2 bis 4 C-Atomen, bevorzugt Alkenyloxy,

bis

soweit vorhanden, jeweils unabhängig voneinander

bevorzugt

bevorzugt

und, wenn vorhanden,

Z⁵¹ bis Z⁵³ jeweils unabhängig voneinander -CH₂-CH₂-, -CH₂-O-, -CH=CH-, -C≡C-, -COO- oder eine Einfachbindung, bevorzugt -CH₂-CH₂-, -CH₂-O- oder eine Einfachbindung und besonders bevorzugt eine Einfachbindung,
i und j jeweils unabhängig voneinander 0 oder 1,
(i + j) bevorzugt 0 oder 1,
bedeuten.In a further preferred embodiment, the medium contains one or more compounds of the formula V.

wherein
R ⁵¹ and R ⁵² independently of one another have the meaning given for R ²¹ and R ²² and are preferably alkyl having 1 to 7 C atoms, preferably n-alkyl, particularly preferably n-alkyl having 1 to 5 C atoms, alkoxy having 1 up to 7 C atoms, preferably n-alkoxy, particularly preferably n-alkoxy having 2 to 5 C atoms, alkoxyalkyl, alkenyl or alkenyloxy having 2 to 7 C atoms, preferably having 2 to 4 C atoms, preferably alkenyloxy,

to

if available, each independently

prefers

prefers

and, if available,

Z ⁵¹ to Z ^{53 are} each independently of one another -CH ₂ -CH ₂ -, -CH ₂ -O-, -CH = CH-, -C≡C-, -COO- or a single bond, preferably -CH ₂ -CH ₂ - , -CH ₂ -O- or a single bond and particularly preferably a single bond,
i and j are each independently 0 or 1,
(i + j) preferably 0 or 1,
mean.

worin die Parameter die oben unter Formel V gegebenen Bedeutungen haben und
Y⁵ H oder F bedeutet und bevorzugt
R⁵¹ Alkyl mit 1 bis 7 C-Atomen oder Alkenyl mit 2 bis 7 C-Atomen und
R⁵² Alkyl mit 1 bis 7 C-Atomen, Alkenyl mit 2 bis 7 C-Atomen oder Alkoxy mit 1 bis 6 C-Atomen, bevorzugt Alkyl oder Alkenyl, besonders bevorzugt Alkenyl,
bedeuten.In a further preferred embodiment, the medium comprises one or more compounds selected from the formula V selected from the group of the compounds of the formulas V-1 to V-10, preferably selected from the group of the compounds of the formulas V-1 to V-5,

wherein the parameters have the meanings given above under formula V, and
Y ^{5 is} H or F and preferably
R ^{51 is} alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms and
R ^{52 is} 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 alkenyl,
mean.

worin
Alkyl und Alkyl' unabhängig voneinander Alkyl mit 1 bis 7 C-Atomen, bevorzugt mit 2 bis 5 C-Atomen,
Alkoxy Alkoxy mit 1 bis 5 C-Atomen, bevorzugt mit 2 bis 4 C-Atomen.In a further preferred embodiment, the medium contains one or more compounds of the formula V-1 selected from the group of the compounds of the formulas V-1a and V-1b, preferably of the formula V-1b,

wherein
Alkyl and alkyl 'independently of one another alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms,
Alkoxy alkoxy having 1 to 5 carbon atoms, preferably having 2 to 4 carbon atoms.

worin
Alkyl und Alkyl' unabhängig voneinander Alkyl mit 1 bis 7 C-Atomen, bevorzugt mit 2 bis 5 C-Atomen und
Alkenyl Alkenyl mit 2 bis 7 C-Atomen, bevorzugt mit 2 bis 5 C-Atomen bedeuten.In a further preferred embodiment, the medium comprises one or more compounds of the formula V-3 selected from the group of the compounds of the formulas V-3a and V-3b,

wherein
Alkyl and alkyl 'independently of one another alkyl having 1 to 7 carbon atoms, preferably having 2 to 5 carbon atoms and
Alkenyl alkenyl having 2 to 7 carbon atoms, preferably having 2 to 5 carbon atoms.

worin
Alkyl und Alkyl' unabhängig voneinander Alkyl mit 1 bis 7 C-Atomen, bevorzugt mit 2 bis 5 C-Atomen.In a further preferred embodiment, the medium contains one or more compounds of the formula V-4 selected from the group of the compounds of the formulas V-4a and V-4b,

wherein
Alkyl and alkyl 'independently of one another alkyl having 1 to 7 carbon atoms, preferably having 2 to 5 carbon atoms.

worin
R⁶¹ einen unsubstituierten Alkylrest mit 1 bis 7 C-Atomen oder bevorzugt einen n-Alkylrest, besonders bevorzugt mit 2, 3, 4 oder 5 C-Atomen, und
R⁶² einen unsubstituierten Alkylrest mit 1 bis 7 C-Atomen oder einen unsubstituierten Alkoxyrest mit 1 bis 6 C-Atomen, beide bevorzugt mit 2 bis 5 C-Atomen,
bedeuten.In a further embodiment, the medium optionally contains one or more compounds of the formula VI

wherein
R ^{61 is} an unsubstituted alkyl radical having 1 to 7 C atoms or preferably an n-alkyl radical, more preferably having 2, 3, 4 or 5 C atoms, and
R ^{62 is} an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms, both preferably having 2 to 5 C atoms,
mean.

The medium according to the invention particularly preferably contains
one or more compounds of formula VI in a total concentration in the range of 1% or more to 30% or less, preferably in the range of 3% or more to 20% or less, more preferably in the range of 5% or more to 15% or fewer.

worin
Alkyl und Alkyl' unabhängig voneinander Alkyl mit 1 bis 5 C-Atomen, bevorzugt mit 2 bis 5 C-Atomen,
Alkoxy Alkoxy mit 1 bis 5 C-Atomen, bevorzugt mit 2 bis 4 C-Atomen,
bedeuten.In a particularly preferred embodiment, the medium contains one or more compounds of the formula VI selected from the group of the compounds of the formulas VI-1 to VI-2,

wherein
Alkyl and alkyl 'independently of one another alkyl having 1 to 5 C atoms, preferably having 2 to 5 C atoms,
Alkoxy alkoxy having 1 to 5 C atoms, preferably having 2 to 4 C atoms,
mean.

In a particularly preferred embodiment, the media according to the invention comprise one or more compounds of the formula VI-1a and VI-2a.

In a particularly preferred embodiment, the media according to the invention comprise one or more compounds selected from the group of the compounds of the formulas OH-1 to OH-6

These compounds are ideal for stabilizing the media against thermal stress.

The present invention also provides electro-optical displays or electro-optical components containing liquid-crystalline media according to the invention. Preference is given to electro-optical displays which are based on the IPS or the FFS effect and in particular those which are activated by means of an active matrix addressing device. Accordingly, the use of a liquid-crystalline medium according to the invention in an electro-optical display or in an electro-optical component is likewise an object of the present invention, as well as a process for the preparation of the liquid-crystalline media according to the invention, characterized in that the compound of the formula I with one or more compounds which one or more compounds of formula III, preferably with one or more compounds of the partial formula III-1 and / or III-2 and / or III-3 and / or III-4 and / or III-5 and / or III-6 and / or III-7, more preferably one or more compounds of two or more, preferably of three or more, different of these formulas, and most preferably of four or five of these III-1, III-2, III-3, III -4, III-5, III-6 and III-7, with one or more further compounds, preferably selected from the group of the compounds of the formulas IV-1 to IV-4 and d / or V and / or VI is mixed.

In addition, the present invention relates to a process for stabilizing a liquid-crystalline medium which contains one or more compounds of the formula II, if appropriate one or more compounds of the formula III and / or one or more compounds of the formula IV and / or one or more compounds of the formula V, characterized in that one or more compounds of the formula I will be added to the medium.

worin n 0, 1, 2, 3, 4, 5 oder 6, bevorzugt 2 oder 4, besonders bevorzugt 2, bedeutet, bevorzugt in einer Konzentration vom 0,1 bis 5% besonders bevorzugt vom 0,2 bis 1%. Besonders bevorzugte Ausführungsformen der vorliegenden Erfindung erfüllen eine oder mehrere der folgenden Bedingungen, wobei die Akronyme (Abkürzungen) in den Tabellen A bis C erläutert und in Tabelle D durch Beispiele illustriert sind.

• i. Das flüssigkristalline Medium hat eine Doppelbrechung von 0,090 oder mehr, besonders bevorzugt von 0,100 oder mehr und, ganz besonders besonders bevorzugt, von 0,110 oder mehr.
• ii. Das flüssigkristalline Medium hat eine Doppelbrechung von 0,150 oder weniger, besonders bevorzugt von 0,140 oder weniger und, ganz besonders besonders bevorzugt, von 0,120 oder weniger.
• iii. Das flüssigkristalline Medium hat eine Doppelbrechung im Bereich von 0,100 oder mehr bis 0,120 oder weniger, bevorzugt von 0,100 oder mehr bis 0,1150 oder weniger.
• iv. Das flüssigkristalline Medium hat eine negative dielektrische Anisotropie mit einem Betrag von 2,0 oder mehr, besonders bevorzugt von 2,5 oder mehr.
• v. Das flüssigkristalline Medium hat eine negative dielektrische Anisotropie mit einem Betrag von 6,0 oder weniger, besonders bevorzugt von 5,0 oder weniger und, ganz besonders bevorzugt, von 4,5 oder weniger.
• vi. Das flüssigkristalline Medium hat eine negative dielektrische Anisotropie mit einem Betrag im Bereich von 3,5 oder mehr bis 4,4 oder weniger.
• vii. Das flüssigkristalline Medium enthält eine oder mehrere besonders bevorzugte Verbindungen der Formeln II ausgewählt aus den nachfolgend genannten Teilformeln:
  
  worin Alkyl die oben gegebene Bedeutung besitzt und bevorzugt, jeweils unabhängig voneinander Alkyl mit 1 bis 6, bevorzugt mit 2 bis 5 C-Atomen und besonders bevorzugt n-Alkyl, bedeutet.
• viii. Die Gesamtkonzentration der Verbindungen der Formel II im Gesamtgemisch beträgt 20% oder mehr, bevorzugt 30% oder mehr und liegt bevorzugt im Bereich von 30% oder mehr bis 49% oder weniger, besonders bevorzugt im Bereich von 30% oder mehr bis 45% oder weniger, und ganz besonders bevorzugt im Bereich von 30% oder mehr bis 40% oder weniger.
• ix. Das flüssigkristalline Medium enthält eine oder mehrere Verbindungen der Formel II ausgewählt aus der Gruppe der Verbindungen folgenden Formeln: CC-n-V, insbesondere bevorzugt CC-3-V, bevorzugt in einer Konzentration von bis zu 45% oder weniger, besonders bevorzugt bis zu 40% oder weniger, und optional zusätzlich CC-3-V1, bevorzugt in einer Konzentration von bis zu 12% oder weniger, und/oder CC-4-V oder CC-5-V, bevorzugt in einer Konzentration von bis zu 20% oder weniger, besonders bevorzugt bis zu 10% oder weniger.
• x. Die Gesamtkonzentration der Verbindungen der Formel CC-3-V im Gesamtgemisch beträgt 25% oder mehr, bevorzugt 30% oder mehr.
• xi. Der Anteil an Verbindungen der Formeln III-1 bis III-7 im Gesamtgemisch beträgt 50% oder mehr und bevorzugt 85% oder weniger.
• xii. Das flüssigkristalline Medium besteht im Wesentlichen aus Verbindungen der Formeln I, II, III, IV, V und und VI, bevorzugt aus Verbindungen der Formeln I, II, III und IV.
• xiii. Das flüssigkristalline Medium enthält eine oder mehrere Verbindungen der Formel V, bevorzugt der Foremln V-1 und/oder V-2, vorzugsweise in einer Gesamtkonzentration von 20% oder mehr, insbesondere von 25% oder mehr, und ganz besonders bevorzugt von 30% oder mehr bis 50% oder weniger.

The liquid crystal media according to the present invention may contain one or more chiral compounds. In a particularly preferred embodiment of the present invention, the liquid-crystalline media contain one or more compounds of the formula

wherein n is 0, 1, 2, 3, 4, 5 or 6, preferably 2 or 4, particularly preferably 2, preferably in a concentration of 0.1 to 5%, particularly preferably from 0.2 to 1%. Particularly preferred embodiments of the present invention fulfill one or more of the following conditions, with the acronyms (abbreviations) illustrated in Tables A to C and illustrated in Table D by Examples.

• i. The liquid-crystalline medium has a birefringence of 0.090 or more, more preferably 0.100 or more, and most preferably 0.110 or more.
• II. The liquid-crystalline medium has a birefringence of 0.150 or less, more preferably 0.140 or less, and most preferably 0.120 or less.
• iii. The liquid-crystalline medium has a birefringence in the range of 0.100 or more to 0.120 or less, preferably 0.100 or more to 0.1150 or less.
• iv. The liquid-crystalline medium has a negative dielectric anisotropy of an amount of 2.0 or more, more preferably 2.5 or more.
• v. The liquid-crystalline medium has a negative dielectric anisotropy of 6.0 or less, more preferably 5.0 or less, and most preferably 4.5 or less.
• vi. The liquid-crystalline medium has a negative dielectric anisotropy in an amount ranging from 3.5 or more to 4.4 or less.
• vii. The liquid-crystalline medium contains one or more particularly preferred compounds of the formulas II selected from the sub-formulas mentioned below:
  
  wherein alkyl has the meaning given above and preferably, in each case independently of one another alkyl having 1 to 6, preferably having 2 to 5 carbon atoms and particularly preferably n-alkyl.
• viii. The total concentration of the compounds of the formula II in the total mixture is 20% or more, preferably 30% or more, and is preferably in the range of 30% or more to 49% or less, more preferably in the range of 30% or more to 45% or less , and most preferably in the range of 30% or more to 40% or less.
• ix. The liquid-crystalline medium contains one or more compounds of the formula II selected from the group of the compounds: CC-nV, more preferably CC-3-V, preferably in a concentration of up to 45% or less, more preferably up to 40% or less, and optionally additionally CC-3-V1, preferably in a concentration of up to 12% or less, and / or CC-4-V or CC-5-V, preferably in a concentration of up to 20% or less , more preferably up to 10% or less.
• x. The total concentration of the compounds of the formula CC-3-V in the total mixture is 25% or more, preferably 30% or more.
• xi. The proportion of compounds of the formulas III-1 to III-7 in the total mixture is 50% or more and preferably 85% or less.
• xii. The liquid-crystalline medium consists essentially of compounds of the formulas I, II, III, IV, V and VI, preferably of compounds of the formulas I, II, III and IV.
• xiii. The liquid-crystalline medium contains one or more compounds of the formula V, preferably the formula V-1 and / or V-2, preferably in a total concentration of 20% or more, in particular 25% or more, and most preferably 30% or more to 50% or less.

Another object of the invention is an electro-optical display with an active matrix addressing based on the IPS or the FFS effect, characterized in that it contains as a dielectric liquid-crystalline medium according to the present invention, which has a negative dielectric anisotropy and a Contains compound of formula I.

The liquid-crystal mixture preferably has a nematic phase range with a width of at least 80 degrees and a flow viscosity ν ₂₀ of at most 30 mm ² · s ^-1 at 20 ° C.

The liquid-crystal mixture according to the invention has a Δ∈ of from -0.5 to -6.0, in particular from -1.5 to -5.5, and very particularly preferably from -3.5 to -4.4, where Δ∈ the dielectric anisotropy means.

The rotational viscosity γ ₁ is preferably 180 mPa · s or less, preferably 150 mPa · s or less, more preferably 120 mPas, still more preferably 100 mPa · s or less, still more preferably 90 mPa · s or less. The mixtures of the invention are suitable for all IPS TFT applications, such. Conventional IPS, super IPS, and FFS and PALC applications, as well as polymer stabilized IPS or FFS applications with negative Δε.

The nematic liquid-crystal mixtures in the displays according to the invention generally contain two components A and B, which in turn consist of one or more individual compounds.

The liquid-crystalline media according to the invention preferably contain 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 formulas I, II and / or III and / or IV and / or V, and / or VI.

The liquid-crystalline media according to the invention may optionally also contain more than 18 compounds. In this case, they preferably contain 18 to 25 compounds.

In addition to compounds of formulas I to VI also other ingredients may be present, for. B. in an amount of up to 25%, but preferably up to 10%, in particular up to 10%, of the total mixture.

Optionally, the media of the invention may also contain a dielectrically positive component whose total concentration is preferably 10% or less based on the total medium.

In a preferred embodiment, the liquid-crystal media according to the invention contain 10 ppm or more to 2,000 ppm or less, preferably 100 ppm or more to 1,500 ppm or less, more preferably 200 ppm or more to 1,000 ppm or less of the compounds of the formula I and 20% or more to 80% or less, preferably 25% or more to 70% or less, more preferably 40% or more to 60% or less, of compounds of formula II and / or 5% or more to 70% or less to compounds of the formula III.

In a preferred embodiment, the liquid-crystal media according to the invention contain compounds selected from the group of the compounds of the formulas I, II, III, IV and V, preferably selected from the group of the compounds of the formulas I, II, III and IV, preferably they are predominantly, especially preferably substantially and very particularly preferably almost completely from the compounds of the formulas mentioned.

The liquid-crystal media of the invention preferably have a nematic phase of at least -20 ° C or less to 70 ° C or more, more preferably -30 ° C or less 80 ° C or more, more preferably from -40 ° C or less to 85 ° C or more, and most preferably from -40 ° C or less to 90 ° C or more.

In this case, the term "having a nematic phase" on the one hand means that no smectic phase and no crystallization is observed at low temperatures at the corresponding temperature and, on the other hand, that no clarification occurs during heating from the nematic phase. The investigation at low temperatures is carried out in a flow viscometer at the appropriate temperature and checked by storage in test cells of a corresponding electro-optical layer thickness for at least 100 hours. When the storage stability at a temperature of -20 ° C in a corresponding test cell is 1,000 hours or more, the medium is said to be stable at this temperature. At temperatures of -30 ° C or -40 ° C the corresponding times are 500 h or 250 h. 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 characterized by values of the optical anisotropies in the middle to low range. The values of the birefringence are preferably in the range of 0.065 or more to 0.140 or less, particularly preferably in the range of 0.090 or more to 0.130 or less, very particularly preferably in the range of 0.095 or more to 0.120 or less and in particular 0.111 +/- 0.002. In this embodiment, the liquid-crystal media according to the invention have a negative dielectric anisotropy and have relatively high values of the amount of the dielectric anisotropy (| Δε |), which is preferably in the range from 3.0 or more to 5.5 or less, more preferably to 5, 5 or less, more preferably from 3.3 or more to 5.0 or less, more preferably from 3.4 or more to 4.5 or less and most preferably from 3.5 or more to 4.4 or less, lie.

The liquid crystal media of the present invention have relatively small values for the threshold voltage (V ₀ ) ranging from 1.7 V or more to 2.5 V or less, preferably from 1.8 V or more to 2.4 V or less, more preferably from 1.9 V or more to 2.3 V or less, and more preferably from 1.95 V or more to 2.1 V or less.

In a further preferred embodiment, the liquid-crystal media according to the invention preferably have relatively low values of the average dielectric anisotropy (ε _av. ≡ (ε || + 2ε⊥ / 3), which is preferably in the range from 4.0 or more to 6.0 or less , preferably from 4.4 or more to 5.5 or less, even more preferably from 4.5 or more to 5.3 or less, more preferably from 4.6 or more to 5.1 or less, and most preferably from 4.7 or more to 4.9 or less.

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

As a rule, liquid-crystal media with a low drive voltage or threshold voltage have a lower HR than those with a larger drive voltage or threshold voltage and vice versa.

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

In the present application, the term "compounds", also written as "compound (s)", unless explicitly stated otherwise, means both one or more compounds.

The individual compounds are, unless stated otherwise, in the mixtures in concentrations generally from 1% or more to 30% or less, preferably from 2% or more to 30% or less, and more preferably from 3% or more to 16% or less used.

In a preferred embodiment, the liquid-crystalline media according to the invention contain
the compound of the formula I and
one or more compounds of the formula II, preferably selected from the group of the compounds of the formulas CC-nV preferably selected from the group of the compounds of the formulas CC-2-V, CC-3-V, CC-4-V and CC-5 -V, more preferably selected from the group of the compounds CC-2-V, CC-3-V and CC-4-V, very particularly preferably the compound CC-3-V and optionally additionally the compound CC-3-V1, and or
one or more compounds of the formula VI, preferably selected from the group of the compounds of the formulas CC-nm and CC-n-Om, preferably selected from the group of the compounds of the formulas CC-1-3, CC-2-3, CC- 3-3, CC-3-4, CC-3-5, CC-3-O1 and CC-3-O2, more preferably selected from the group of compounds CC-2-3, CC-3-4 and CC- 3-5 and / or
one or more compounds of the formula III-1, preferably of the formula Y-nO-Om, selected from the group of the compounds of the formulas Y-3O-O5, Y-3O-O3, Y-4O-O4 and Y-2O-O4 .
one or more compounds of the formula III-2, preferably of the formula CY-n-Om, selected from the group of the compounds of the formulas CY-3-O2, CY-3-O4, CY-5-O2 and CY-5-O4 .
one or more compounds of the formula III-3, preferably of the formula PY-n-Om, selected from the group of the compounds of the formulas PY-3-O2 and PY-3-O3,
one or more compounds of the formula III-4, preferably selected from the group of the compounds of the formula CCY-nm and CCY-n-Om, preferably of the formula CCY-n-Om, preferably selected from the group of the compounds of the formulas CCY-3 -O2, CCY-2-O2, CCY-3-O1, CCY-3-O3, CCY-4-O2, CCY-3-O2 and CCY-5-O2,
optionally, preferably compulsorily, one or more compounds of the formula III-5, preferably of the formula CLY-n-Om, preferably selected from the group of the compounds of the formulas CLY-2-O4, CLY-3-O2, CLY-3-O3 .
one or more compounds of the formula III-6, preferably of the formula CPY-n-Om, preferably selected from the group of the compounds of the formulas CPY-2-O2 and CPY-3-O2, CPY-4-O2 and CPY-5 O2,
one or more compounds of the formula III-7, preferably of the formula PYP-nm, preferably selected from the group of the compounds of the formulas PYP-2-3 and PYP-2-4.

• – „enthalten”: die Konzentration der betreffenden Bestandteile in der Zusammensetzung beträgt bevorzugt 5% oder mehr, besonders bevorzugt 10% oder mehr, ganz besonders bevorzugt 20% oder mehr,
• – „überwiegend bestehen aus”: die Konzentration der betreffenden Bestandteile in der Zusammensetzung beträgt bevorzugt 50% oder mehr, besonders bevorzugt 55% oder mehr und ganz besonders bevorzugt 60% oder mehr,
• – „im wesentlichen bestehen aus”: die Konzentration der betreffenden Bestandteile in der Zusammensetzung beträgt bevorzugt 80% oder mehr, besonders bevorzugt 90% oder mehr und ganz besonders bevorzugt 95% oder mehr und
• – „nahezu vollständig bestehen aus”: die Konzentration der betreffenden Bestandteile in der Zusammensetzung beträgt bevorzugt 98% oder mehr, besonders bevorzugt 99% oder mehr und ganz besonders bevorzugt 100,0%.

For the purposes of the present invention, in connection with the indication of the constituents of the compositions, if not stated otherwise in individual cases:

• "Contain": the concentration of the constituents in the composition is preferably 5% or more, more preferably 10% or more, most preferably 20% or more,
• "Predominantly consisting of": the concentration of the constituents in the composition is preferably 50% or more, more preferably 55% or more and most preferably 60% or more,
• "Essentially consist of": the concentration of the constituents in the composition is preferably 80% or more, more preferably 90% or more and most preferably 95% or more and
• "Almost completely composed": the concentration of the constituents in question in the composition is preferably 98% or more, more preferably 99% or more and most preferably 100.0%.

This applies both to the media as compositions with their constituents, which may be components and compounds, as well as to the components with their constituents, the compounds. Only in relation to the concentration of a single compound in relation to the total medium does the term contain: the concentration of the compound in question is preferably 1% or more, more preferably 2% or more, most preferably 4% or more.

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

trans-1,4-Cyclohexylen und

1,4-Phenylen.For the present invention

trans-1,4-cyclohexylene and

1,4-phenylene.

For the purposes of the present invention, the terms "dielectrically positive compounds" mean those compounds with a Δε> 1.5, "dielectrically neutral compounds" those with -1.5 ≦ Δε ≦ 1.5 and "dielectrically negative "compounds with Δε <-1.5. Here, the dielectric anisotropy of the compounds is determined by 10% of the compounds are dissolved in a liquid crystalline host and the capacity of the resulting mixture in at least one test cell with 20 micron layer thickness is determined with homeotropic and homogeneous surface orientation at 1 kHz. The measurement voltage is typically 0.5 V to 1.0 V, but it is always lower than the capacitive threshold of the liquid crystal mixture under investigation.

The host mixture used for dielectrically positive and dielectrically neutral compounds is ZLI-4792 and for dielectrically negative compounds ZLI-2857, both from Merck KGaA, Germany. From the change in the dielectric constant of the host mixture after addition of the test compound and extrapolation to 100% of the compound used, the values for the respective compounds to be investigated are obtained. The compound to be tested is dissolved to 10% in the host mixture. If the solubility of the substance is too low for this purpose, the concentration is gradually halved until the investigation can be carried out at the desired temperature.

If necessary, the liquid-crystal media according to the invention can also contain further additives, such as, for example, B. stabilizers and / or pleochroic dyes and / or chiral dopants in the usual amounts. The amount of these additives used is preferably 0% or more to 10% or less in total, based on the amount of the entire mixture, more preferably 0.1% or more to 6% or less. The concentration of the individual compounds used is preferably 0.1% or more to 3% or less. The concentration of these and similar additives is usually not taken into account in the indication of the concentrations and the concentration ranges of the liquid crystal compounds in the liquid-crystal media.

In a preferred embodiment, the liquid-crystal media according to the invention contain a polymer precursor which contains one or more reactive compounds, preferably reactive mesogens and, if required, further additives such as, for example, B. polymerization initiators and / or polymerization moderators in the usual amounts. The amount of these additives used is generally 0% or more to 10% or less based on the amount of the whole mixture, preferably 0.1% or more to 2% or less. The concentration of these and similar additives is not taken into account in the indication of the concentrations and the concentration ranges of the liquid crystal compounds in the liquid-crystal media.

The compositions consist of several compounds, preferably from 3 or more to 30 or less, more preferably from 6 or more to 20 or less and most preferably from 10 or more to 16 or fewer compounds that are mixed in a conventional manner. In general, the desired amount of the minor components is dissolved in the components that make up the main ingredient of the mixture. This is conveniently carried out at elevated temperature. If the selected temperature is above the clearing point of the main constituent, the completion of the dissolution process is particularly easy to observe. However, it is also possible, the liquid crystal mixtures in other conventional ways, for. B. using premixes or from a so-called "multi-bottle system" produce.

The mixtures according to the invention show very broad nematic phase ranges with clearing points of 65 ° C. or more, very favorable 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 γ ₁ .

The compounds of the formula I are according to methods known to the person skilled in the art (see B: Houben Weil "Methods of Organic Chemistry" ) accessible.

• 1) Synthese von Bis(2,2,6,6-tetramethyl-4-piperidinyl-1-oxyl)eicosandiat A
  
  5.00 g (14.6 mmol) Eicosandisäure, 6.50 g (37.7 mmol) 4-Hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (freies Radikal) und 0.30 g (2.46 mmol) 4-(Dimethylamino)-pyridin werden in 100 mL Dichlormethan (DCM) gelöst und auf 4°C gekühlt. Es wird nun portionsweise mit 7.00 g (36.5 mmol) N-(3-Dimethylaminopropyl)-N'-carbodiimid-hydrochlorid versetzt und für 16 h bei Raumtemperatur (RT) gerührt. Es entsteht eine klare rote Reaktionslösung, die mit gesättigter NaCl-Lösung gewaschen wird. Die Wasserphase wird mit DCM extrahiert und die vereinigten organischen Phasen werden über Natriumsulfat getrocknet, filtriert und eingeengt. Das Rohprodukt wird über 400 mL Kieselgel mit Dichlormethan/MTB-Ether (Gradient: 95:5 bis auf 9:1) chromatographiert und das erhaltene Produkt 2 X aus MTB-Ether bei 5°C kristallisiert. Man erhält das Produkt mit 5.7 g als orange Kristalle. MS (EI): 650 [M*]
• 2) Synthese von Eicosandisäure bis-(2,2,6,6-tetramethyl-piperidin-4-yl)ester 1 (CAS 156693-76-4)
  
  4.40 g (6.76 mmol) Verbindung A, 3.5 g Eisen (zur Analyse durch Reduktion hergestellt, Korngröße 10 μm) werden bei Raumtemperatur (RT) in 100 mL Eisessig suspendiert. Die Reaktionsmischung wird anschließend langsam auf 70°C Badtemperatur erhitzt (Innentemperatur 65°C). Es tritt eine Farbänderung von Rot-Grau zu Grau ein und es wird für 4 h bei dieser Temperatur und anschließend für 16 h bei 40°C gerührt. Das Reaktionsgemisch wird auf RT abgekühlt und unter Vakuum eingeengt. Der erhaltene Rückstand wird in Wasser gelöst und von unlöslichen Eisenbestandteilen abgetrennt. Die Wasserphase wird vorsichtig mit Natriumhydrogencarbonatlösung auf pH = 8 eingestellt und mit Dichlormethan (DCM) extrahiert und über Natriumsulfat getrocknet, filtriert und eingeengt. Das erhaltene Rohprodukt wird in siedenden MTB-Ether gelöst, von unlöslichen Bestandteilen filtriert und bei 5°C kristallisiert. Man erhält das Produkt als farblose Kristalle, die bei 120°C und 0.08 mbar durch Aufschmelzen getrocknet werden. Man erhält 2.48 g des Produktes. Phasen: K 92°C I MS (EI): 621 [M⁺] ¹H NMR (500 MHz, CDCl₃) δ = 1.18–1.08 ppm (m, 18H), 1.36–1.19 (m, 40H), 1.61 (quin, 7.35 Hz, 4H), 1.91 (dd, 12.49, 4.18 Hz, 4H, C(CH₃)₂CH₂CH-O), 2.27 (t, 7.51 Hz, 4H CH₂C(O)O), 5.19 (tt, 11.43, 4.19 Hz, 2H CHOC(O)).

The compounds of the formula I which have not been described so far were synthesized as follows.

• 1) Synthesis of bis (2,2,6,6-tetramethyl-4-piperidinyl-1-oxyl) eicosanediate A
  
  5.00 g (14.6 mmol) of eicosanedioic acid, 6.50 g (37.7 mmol) of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (free radical) and 0.30 g (2.46 mmol) of 4- (dimethylamino) -pyridine dissolved in 100 mL dichloromethane (DCM) and cooled to 4 ° C. 7.00 g (36.5 mmol) of N- (3-dimethylaminopropyl) -N'-carbodiimide hydrochloride are then added in portions and stirred for 16 h at room temperature (RT). The result is a clear red reaction solution, which is washed with saturated NaCl solution. The water phase is extracted with DCM and the combined organic phases are dried over sodium sulfate, filtered and concentrated. The crude product is chromatographed over 400 mL silica gel with dichloromethane / MTB ether (gradient: 95: 5 to 9: 1) and the product obtained 2 x crystallized from MTB ether at 5 ° C. The product is obtained with 5.7 g as orange crystals. MS (EI): 650 [M *]
• 2) Synthesis of bis (2,2,6,6-tetramethylpiperidin-4-yl) eicosanedioic acid 1 (CAS 156693-76-4)
  
  4.40 g (6.76 mmol) of compound A, 3.5 g of iron (prepared for analysis by reduction, particle size 10 μm) are suspended at room temperature (RT) in 100 mL glacial acetic acid. The reaction mixture is then slowly heated to 70 ° C bath temperature (internal temperature 65 ° C). There is a change in color from red-gray to gray and it is stirred for 4 h at this temperature and then for 16 h at 40 ° C. The reaction mixture is cooled to RT and concentrated in vacuo. The residue obtained is dissolved in water and separated from insoluble iron components. The aqueous phase is carefully adjusted to pH = 8 with sodium bicarbonate solution and extracted with dichloromethane (DCM) and dried over sodium sulfate, filtered and concentrated. The crude product obtained is dissolved in boiling MTB ether, filtered from insoluble constituents and crystallized at 5 ° C. The product is obtained as colorless crystals, which are dried by melting at 120 ° C and 0.08 mbar. This gives 2.48 g of the product. Phases: K 92 ° CI MS (EI): 621 [M ^{+] 1} H NMR (500 MHz, CDCl ₃₎ δ = 1:18 to 1:08 ppm (m, 18H), 1:36 to 1:19 (m, 40H), 1.61 (quin , 7.35 Hz, 4H), 1.91 (dd, 12.49, 4.18 Hz, 4H, C (CH ₃ ) ₂ CH ₂ CH-O), 2.27 (t, 7.51 Hz, 4H CH ₂ C (O) O), 5.19 ( t, 11.43, 4.19 Hz, 2H CHOC (O)).

It will be understood by those skilled in the art that the media of this invention for use in IPS and FFS displays may also include compounds wherein, for example, H, N, O, Cl, F are replaced by the corresponding isotopes. The liquid-crystal mixtures can also be stabilized by polymerization of corresponding polymer precursors, in particular by reactive mesogens.

The structure of the liquid crystal displays according to the invention corresponds to the usual geometry, as z. In EP-OS 0 240 379 , is described.

By means of suitable additives, the liquid crystal phases according to the invention can be modified such that they can be used in any type of z. B. IPS, FFS or ASM-VA LCD display can be used.

In the following Table E possible dopants are given, which can be added to the mixtures according to the invention. If the mixtures contain one or more dopants, it is used in amounts of 0.01% to 4%, preferably 0.1% to 1.0%.

Stabilizers which may be added, for example, to the mixtures according to the invention, preferably in amounts of from 0.01% to 6%, in particular from 0.1% to 3%, are mentioned below in Table F.

All concentrations are for the purposes of the present invention, unless explicitly stated otherwise, given in percent by weight and refer to the corresponding mixture or mixture component, unless explicitly stated otherwise.

All values given for temperatures in the present application, such. B. the melting point T (C, N), the transition from the smectic (S) to the nematic (N) phase T (S, N) and the clearing point T (N, I), are in degrees Celsius (° C) and all temperature differences are given in degrees of difference (° or degrees) unless explicitly stated otherwise.

The term "threshold voltage" for the present invention refers to the capacitive threshold (V ₀ ), also called Freedericksz threshold, unless explicitly stated otherwise.

All physical properties are and have been after "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status Nov. 1997, Merck KGaA, Germany are determined and are valid for a temperature of 20 ° C and Δn is determined at 589 nm and Δε at 1 kHz, unless explicitly stated otherwise.

The electro-optical properties, eg. As the threshold voltage (V ₀ ) (capacitive measurement), as well as the switching behavior, determined in test cells manufactured at Merck Japan. The measuring cells have substrates of sodium glass (sodalime glass) and are in an ECB or VA configuration with polyimide orientation layers (SE-1211 with thinner ** 26 (mixing ratio 1: 1) both from Nissan Chemicals, Japan) which are perpendicular to each other are rubbed and that cause a homeotropic orientation of the liquid crystals carried out. The area of the transparent, nearly square electrodes made of ITO is 1 cm ² .

The threshold voltage can be measured on the one hand electro-optically (transmission to voltage, often referred to as V _th ) on the other hand capacitive (capacitance to voltage, typically referred to as V ₀ ). Unless otherwise stated, the capacitive method uses sodium glass cells manufactured by Merck Japan. Unless stated otherwise, the polyimide used is JALS-2096-R1 and comes from JSR and leads to a homeotropic orientation. These cells are unstressed. The electrode surface is circular with an effective area of 1.13 cm ² . For the electro-optical measurements cells are used, as they are known for the FFS technology with Kammeletroden (so-called pixel electrodes) on a potential and a full-surface ITO layer (so-called common electrode) at the other potential separated by an insulating layer. The polyimide used is directed to the task and typically leads to a planar orientation. The polyimide can be rubbed. But it can also be oriented differently, for. B. by a photoprocess. The electrode is nearly square with an effective area of 1 cm ² .

The liquid crystal mixtures used are not mixed with a chiral dopant unless otherwise stated, but they are also particularly suitable for applications in which such a doping is required.

The HR is determined in test cells manufactured by Merck Japan. The measuring cells have substrates made of sodium glass (sodalime glass) and are designed with a planar polyimide orientation layer with a layer thickness of 50 nm to 150 nm. The layer thickness is uniformly 6.0 microns. The area of the transparent electrodes made of ITO is 1 cm ² .

The HR is determined at 20 ° C (HR ₂₀ ) and after 5 minutes in the oven at 100 ° C (HR ₁₀₀ ) in a commercially available device from the company Autronic Melchers, Germany. Alternatively, the HR is determined in the oven at 60 ° C (HR ₆₀ ). The voltage used has a frequency of 60 Hz or 10 Hz.

The accuracy of HR measurements depends on the HR value. The accuracy decreases with decreasing values. The deviations observed in values in the various size ranges are usually in their order of magnitude in the following table together. HR area Deviation (relative) HR values Δ _G HR / HR /% from to approximately 99.6% 100% +/- 0.1 99.0% 99.6% +/- 0.2 98% 99% +/- 0.3 95% 98% +/- 0.5 90% 95% +/- 1 80% 90% +/- 2 60% 80% +/- 4 40% 60% +/- 8 20% 40% +/- 10 10% 20% +/- 20

The stability against irradiation with UV is examined in a "Suntest CPS" a commercial device of the company Heraeus, Germany. The sealed test cells are irradiated for 30 minutes to 144 hours without additional thermal stress. The irradiation power in the wavelength range from 300 nm to 800 nm is 765 W / m ² V. In each test series at least four test cells are examined for each condition and the respective results are given as mean values of the corresponding individual measurements.

Another parameter that can characterize the conductivity of liquid crystal mixtures besides HR is the ion density. High levels of ion density often lead to display errors such as image stamping and flickering. The ion density is preferably determined in test cells available from Merck Japan ^Ltd. are produced. The test cells have substrates of sodium glass (sodalime glass) and are provided with a planar orientation polyimide orientation layer (12) with a polyimide layer thickness of 40 nm. The layer thickness of the liquid-crystal mixture is uniformly 5.8 μm. The area of the circular, transparent electrodes made of ITO, which are additionally equipped with a "guard-ring", is 1 cm ² . The accuracy of the measurement method is approx. ± 15%. The cells are dried overnight in an oven at 120 ° C before filling with the liquid crystal mixture in question.

The ion density is measured using a commercially available device from TOYO, Japan. The measurement method is essentially a measurement method analogous to cyclic voltammetry, as in M. Inoue, "Recent Measurement of Liquid Crystal Material Characterisites", Proceedings IDW 2006, LCT-7-1,647 described. In this case, an applied DC voltage is varied according to a predetermined triangular profile between a positive or negative maximum value. A complete passage through the profile thus forms a measuring cycle. If the applied voltage is large enough for the ions in the field to move to the respective electrode, an ion current is created by discharging the ions. The transferred charge amount is typically in the range of a few pC to a few nC. This requires a high sensitivity detection, which is ensured by the above-mentioned device. The results are displayed in a current / voltage curve. The ion current can be recognized by the appearance of a peak at voltages which are smaller than the threshold voltage of the liquid-crystal mixture. Integration of the peak area gives the value for the ion density of the mixture under investigation. Four test cells are measured per mixture. The repetition frequency of the triangular voltage is 0.033 Hz, the measuring temperature 60 ° C, the maximum voltage ± 3 V to ± 10 V depending on the size of the dielectric anisotropy of the mixture in question.

The rotational viscosity is determined by the method of the rotating permanent magnet and the flow viscosity in a modified Ubbelohde viscometer. For the liquid-crystal mixtures ZLI-2293, ZLI-4792 and MLC-6608, all products of Merck KGaA, Darmstadt, Germany, the values of the rotational viscosity determined at 20 ° C. are 161 mPa · s, 133 mPa · s and 186 mPa · s and the flow viscosity (ν) 21 mm ² · ^{s -1,} 14 mm ² · ^{s -1} and 27 mm ² · ^{s -1.}

V_o

Schwellenspannung, kapazitiv [V] bei 20°C,

n_e

außerordentlicher Brechungsindex gemessen bei 20°C und 589 nm,

n_o

ordentlicher Brechungsindex gemessen bei 20°C und 589 nm,

Δn

optische Anisotropie gemessen bei 20°C und 589 nm,

ε⊥

dielektrische Suszeptibilität senkrecht zum Direktor bei 20°C und 1 kHz,

ε||

dielektrische Suszeptibilität parallel zum Direktor bei 20°C und 1 kHz,

Δε

dielektrische Anisotropie bei 20°C und 1 kHz,

cp. bzw. T(N, I)

Klärpunkt [°C],

ν

Fließviskosität gemessen bei 20°C [mm²·s^–1],

γ₁

Rotationsviskosität gemessen bei 20°C [mPa·s],

K₁

elastische Konstante, ”splay”-Deformation bei 20°C [pN],

K₂

elastische Konstante, ”twist”-Deformation bei 20°C [pN],

K₃

elastische Konstante, ”bend”-Deformation bei 20°C [pN] und

LTS

Tieftemperaturstabilität der Phase („low temperature stability”), bestimmt in Testzellen,

HR

Spannungshaltevermögen („voltage holding ratio”),

Unless explicitly stated otherwise, the following symbols are used:

V _o

Threshold voltage, capacitive [V] at 20 ° C,

n _e

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

n _o

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

.DELTA.n

optical anisotropy measured at 20 ° C and 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,

cp. or T (N, I)

Clearing point [° C],

ν

Flow viscosity measured at 20 ° C [mm ² .s ^-1 ],

γ ₁

Rotational viscosity measured at 20 ° C [mPa · s],

K ₁

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

K ₂

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

K ₃

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

LTS

Low-temperature stability of the phase, determined in test cells,

MR

Voltage holding ratio ("voltage holding ratio"),

The following examples illustrate the present invention without limiting it. However, they show the skilled person preferred mixing concepts with preferably used compounds and their respective concentrations and their combinations with each other. In addition, the examples illustrate which properties and property combinations are accessible.

Tabelle B: Brückenglieder

Tabelle C: Endgruppen

worin n und m jeweils ganze Zahlen und die drei Punkte „...” Platzhalter für andere Abkürzungen aus dieser Tabelle sind.For the present invention and in the following examples, the structures of the liquid crystal compounds are indicated by acronyms, wherein the transformation into chemical formulas according to the following Tables A to C takes place. All radicals C _n H _{2n + 1} , C _m H _{2m + 1} and C _l H _{2l + 1} or C _n H _2n , C _m H _2m and C _l H _2l are straight-chain alkyl radicals or alkylene radicals in each case with n, m or 1 C atoms. Table A lists the ring elements of the cores of the compound, Table B lists the bridge members, and Table C lists the meanings of the symbols for the left and right end groups of the molecules, respectively. The acronyms are composed of the codes for the ring elements with optional join groups, followed by a first hyphen and the codes for the left end group, as well as a second hyphen and the codes for the right end group. Table D summarizes example structures of compounds with their respective abbreviations. Table A: Ring elements

Table B: Bridge links

Table C: end groups

where n and m are integers and the three dots "..." are placeholders for other abbreviations in this table.

The mixtures according to the invention preferably contain, in addition to the compounds of the formulas I, one or more compounds of the compounds mentioned below.

The following abbreviations are used (n, m and z independently of one another in each case an integer, preferably 1 to 6). Table D

Table E lists chiral dopants which are preferably used in the mixtures according to the invention. Table E

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

Table F lists stabilizers which can preferably be used in addition to the compounds of the formula I in the mixtures according to the invention. The parameter n here represents an integer in the range from 1 to 12. In particular, the phenol derivatives shown can be used as additional stabilizers, 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 of Table F, in particular one or more compounds selected from the group of the compounds of the two formulas

Examples

The following examples illustrate the present invention without limiting it in any way. From the physical properties, however, it will be apparent to those skilled in the art which properties can be achieved and in which areas they are modifiable. In particular, therefore, the combination of the various properties that can preferably be achieved, well defined for the expert.

Examples substance

The following substances are preferred substances of the formula I according to the present application, or according to the present application are preferably used substances of the formula I.

Liquid crystal mixtures having the compositions and properties as shown in the following tables are prepared and tested.

Examples:

Stabilizer:

The following stabilizers I-2 and I-6 are investigated by way of example in the mixtures according to the invention

The following host mixture H-1 is prepared and tested. Example 1:

• 1. P-1: Orientierungsschicht AL16301 (Fa. Japan Synthetic Rubber (JSR), Japan)
• 2. P-2: Orientierungsschicht SE6514 (Fa. Nissan Chemical Industries, Japan)
• 3. P-3: Orientierungsschicht SE2414 (Fa. Nissan Chemical Industries, Japan)

The mixture H-1 is divided into several parts and each stabilizers I-2 and I-6 added in different concentrations and then placed in test cells with different orientation layers P-1 to P-3. The resulting mixtures are tested as well as the host mixture as described below. For this purpose, the mixtures are filled in test cells which differ on the ITO electrodes have commercially available orienting agents from the class of polyimides for planar alignment. The following planar orientation layers P1 to P3 are used:

• 1. P-1: orientation layer AL16301 (Japan Synthetic Rubber (JSR), Japan)
• 2. P-2: orientation layer SE6514 (Nissan Chemical Industries, Japan)
• 3. P-3: orientation layer SE2414 (Nissan Chemical Industries, Japan)

The Voltage Holding Ratio (HR) of the mixtures are tested in a test cell with orientation material for planar alignment and flat ITO electrodes for stability in the sinus test. For this purpose, appropriate test cells are exposed to the illumination (so-called "sun test") for 30 to 60 minutes as indicated. Thereafter, the voltage holding ratio is determined after 5 minutes either at room temperature RT, or at a temperature of 60 ° C or 100 ° C, and a voltage of 1 V and a frequency of 60 Hz or 10 Hz. Here, as in the following, six test cells are filled and examined for each individual mixture. The values given are the average of the six individual values and their standard deviation (σ), even in the case that the standard deviation is smaller than the accuracy of the measured values given above.

In addition, the percentage change in HR (HR _SUN / HR _Initial ) after the Suntest is indicated. The most significant variable is the figure of merit (FOM) after the Suntest. It is a measure of the stabilization of the sample, based on the HR measurements, and always refers to the sample without stabilizer at the same PI. The FOM after the Suntest is calculated as: FoM (after Suntest) = [(HR (HALS to Suntest) / HR (no HALS to Suntest)) - 1] x 100 and indicates the percent stabilization in the media of the invention versus the reference (c (rod) = 0) without stabilizer. Table 1a Mixture H-1 Ex. stabilizer c (staff) PI MR (100 ° C / 60 Hz / 1 V) [Ppm] [%] initial value 30 min Suntest M-1-1 none 0 PI-1 65.8 54.5 M-1-2 I-2 100 PI-1 69.9 69.3 M-1-3 I-2 500 PI-1 69.5 70.6 M-1-4 I-2 1000 PI-1 72.2 70.6 M-1-5 I-6 100 PI-1 72.9 71.2 M-1-6 I-6 500 PI-1 71.7 70.9 M-1-7 I-6 1000 PI-1 69.8 70.3 M-1-8 none 0 PI-2 70.5 65.6 M-1-9 I-2 300 PI-2 64.9 74.6 M-1-10 none 0 PI-3 tbd 58.4 M-1-11 I-2 300 PI-3 tbd 75.3 Table 1b Mixture H-1 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM [Ppm] [%] M-1-1 none 0 PI-1 -17.1 - M-1-2 I-2 100 PI-1 -0.8 +27.1 M-1-3 I-2 500 PI-1 +1.5 +29.5 M-1-4 I-2 1000 PI-1 -2.2 +29.5 M-1-5 I-6 100 PI-1 -2.3 +30.6 M-1-6 I-6 500 PI-1 -1.1 +30.0 M-1-7 I-6 1000 PI-1 +0.7 +29.2 M-1-8 none 0 PI-2 -6.9 - M-1-9 I-2 300 PI-2 +14.9 +13.7 M-1-10 none 0 PI-3 tbd - M-1-11 I-2 300 PI-3 tbd -

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntest

Even at relatively low concentrations of compound I-2 and I-6, the HR of the pure M-1-1 mixture (initial HR value, Table 1) is increased, i. h that the compound I-2 and I-6 in a concentration of 100 ppm or from 500 ppm to 1000 ppm has a stabilizing activity in relation to the initial value.

Even more pronounced is the effect after the Suntest both for the compound I-2 and for the compound of formula I-6. As shown in Table 1, the HR of the unstabilized blend on the planar-oriented PI-1 drops significantly to 54%. By contrast, the decrease in HR in the mixtures stabilized with I-2 and I-6 is substantially less or not at all present. Considering the figure of merit after the sinus test, it is clear that the use of I-2 and I-6 stabilizes the mixtures according to the invention in the test cells with PI-1 and PI-3 by 30% and 28%, respectively, compared to the reference can. For PI-2 the effect is also clearly pronounced with + 13%.

This leads to a reduction in the occurrence of image sticking when loaded by the backlight. All stabilizers used here (and in particular the compounds of the formula I-2 and I-6), significantly improve the stability of the mixtures used. This applies in particular to the values after the stress tests. And the stabilization also occurs on other planar alignment layers, as exemplified by the use of PI-2 and PI-3.

Both stabilizer of the formula I-2 and I-6 in this case show a particularly good activity. Without the use of stabilizers, the mixture H-1 could only be used to a limited extent in an LCD. By using the described stabilizers, in particular the compounds of the formulas I-2 and I-6, it is possible to increase the HR to a value which enables use in most corresponding LCDs.

Example 2:

The mixture H-2 is examined as described in Example 1. It is divided into two parts. The first part M-2-1 is examined as such. The second part of the mixture is added to 250 ppm of compound I-2. The mixture "M-2-2" is obtained. All mixtures are investigated as described in Example 1.

Tabelle 2a Mischung H-2 Bsp. Stabilisator c (Stab) PI HR (100°C/60 Hz/1 V) [ppm] [%] Anfangswert 30 min Suntest M-2-1 Keiner 0 PI-2 59,0 56,1 M-2-2 I-2 250 PI-2 56,9 65,6 Tabelle 2b Mischung H-2 Bsp. Stabilisator c (Stab) PI (HR_Sn/HR_In) – 1 FoM [ppm] [%] M-2-1 Keiner 0 PI-2 –4,9 - M-2-2 I-2 250 PI-2 +15,2 +16,9 Also in this example similar results are achieved as in the previous example and the figure of Merit after Suntest has a significant stabilization by almost 17% compared to the reference.

Table 2a Mixture H-2 Ex. stabilizer c (staff) PI MR (100 ° C / 60 Hz / 1 V) [Ppm] [%] initial value 30 min Suntest M-2-1 none 0 PI-2 59.0 56.1 M-2-2 I-2 250 PI-2 56.9 65.6 Table 2b Mixture H-2 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM [Ppm] [%] M-2-1 none 0 PI-2 -4.9 - M-2-2 I-2 250 PI-2 +15.2 +16.9

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntest

Example 3:

Tabelle 3a Mischung H-3 Bsp. Stabilisator c (Stab) PI HR (100°C/60 Hz/1 V) [ppm] [%] Anfangswert 30 min Suntest M-3-1 Keiner 0 PI-2 71,8 64,8 M-3-2 I-2 250 PI-2 66,6 74,5 Tabelle 3b Mischung H-3 Bsp. Stabilisator c (Stab) PI (HR_Sn/HR_In) – 1 FoM [ppm] [%] M-3-1 Keiner 0 PI-2 –9,7 - M-3-2 I-2 250 PI-2 +11,8 +14,9 The mixture H-3 is examined as described in Examples 1 and 2. Also in this example similar results are achieved as in the previous example and the figure of merit has a significant stabilization of almost 15%, compared to the reference.

Table 3a Mixture H-3 Ex. stabilizer c (staff) PI MR (100 ° C / 60 Hz / 1 V) [Ppm] [%] initial value 30 min Suntest M-3-1 none 0 PI-2 71.8 64.8 M-3-2 I-2 250 PI-2 66.6 74.5 Table 3b Mixture H-3 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM [Ppm] [%] M-3-1 none 0 PI-2 -9.7 - M-3-2 I-2 250 PI-2 +11.8 +14.9

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntest

Example 4:

The mixture H-4 is examined as described in the previous examples.

Tabelle 4a Mischung H-4 Bsp. Stabilisator c (Stab) PI HR (100°C/60 Hz/1 V) [ppm] [%] Anfangswert 30 min Suntest M-4-1 Keiner 0 PI-2 64,5 61,7 M-4-2 I-2 250 PI-2 57,2 68,3 Tabelle 4b Mischung H-4 Bsp. Stabilisator c (Stab) PI (HR_Sn/HR_In) – 1 FoM % M-4-1 Keiner 0 PI-2 –4,3 - M-4-2 I-2 250 PI-2 +19,4 +10,6 Also in this example similar results are achieved as in the previous example and the figure of merit has a significant stabilization of over 10%, compared to the reference.

Table 4a Mix H-4 Ex. stabilizer c (staff) PI MR (100 ° C / 60 Hz / 1 V) [Ppm] [ %] initial value 30 min Suntest M-4-1 none 0 PI-2 64.5 61.7 M-4-2 I-2 250 PI-2 57.2 68.3 Table 4b Mix H-4 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM % M-4-1 none 0 PI-2 -4.3 - M-4-2 I-2 250 PI-2 +19.4 +10.6

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntest

Example 5:

The mixture H-5 is examined as described in the previous examples.

Tabelle 5a Mischung H-5 Bsp. Stabilisator c (Stab) PI HR (100°C/60 Hz/1 V) [ppm] [%] Anfangswert 30 min Suntest M-5-1 Keiner 0 PI-2 61,2 52,6 M-5-2 I-2 250 PI-2 58,3 65,0 Tabelle 5b Mischung H-5 Bsp. Stabilisator c (Stab) PI (HR_Sn/HR_In) – 1 FoM [ppm] [%] M-5-1 Keiner 0 PI-2 –14,0 - M-5-2 I-2 250 PI-2 +11,4 +11,4 Also in this example similar results are achieved as in the previous example and the figure of merit has a significant stabilization of over 11%, compared to the reference.

Table 5a Mixture H-5 Ex. stabilizer c (staff) PI MR (100 ° C / 60 Hz / 1 V) [Ppm] [%] initial value 30 min Suntest M-5-1 none 0 PI-2 61.2 52.6 M-5-2 I-2 250 PI-2 58.3 65.0 Table 5b Mixture H-5 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM [Ppm] [%] M-5-1 none 0 PI-2 -14.0 - M-5-2 I-2 250 PI-2 +11.4 +11.4

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntest

Example 6:

The mixture H-6 is assayed as described in the previous examples in test cells with PI-1 and PI-2. The HR measurements in the Tes cells with PI-2 were examined at RT, 10 Hz and 1 V as indicated in the table.

Tabelle 6a Mischung H-6 Bsp. Stabilisator c (Stab) PI HR (100°C/60 Hz/1 V) [ppm] [%] Anfangswert 30 min Suntest M-6-1 Keiner 0 PI-1 52,2 50,6 M-6-2 I-2 250 PI-1 63,2 64,7 M-6-3 I-2 500 PI-1 64,4 66,8 Tabelle 6b Mischung H-6 Bsp. Stabilisator c (Stab) PI (HR_Sn/HR_In) – 1 FoM [ppm] [%] M-6-1 Keiner 0 PI-1 –3,0 - M-6-2 I-2 250 PI-1 +2,3 +27,8 M-6-3 I-2 500 PI-1 +3,7 +32,0 Good results are also achieved in this example, and the Figure of Merit shows a clear stabilization over the reference for PI-1 at 32% as well as for PI-2 at over 11%.

Table 6a Mixture H-6 Ex. stabilizer c (staff) PI MR (100 ° C / 60 Hz / 1 V) [Ppm] [%] initial value 30 min Suntest M-6-1 none 0 PI-1 52.2 50.6 M-6-2 I-2 250 PI-1 63.2 64.7 M-6-3 I-2 500 PI-1 64.4 66.8 Table 6b Mixture H-6 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM [Ppm] [%] M-6-1 none 0 PI-1 -3.0 - M-6-2 I-2 250 PI-1 +2.3 +27.8 M-6-3 I-2 500 PI-1 +3.7 +32.0

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntest

Table 6c Mixture H-6 Ex. stabilizer c (staff) PI MR (RT / 10 Hz / 1 V) [Ppm] [%] initial value 30 min Suntest M-6-1 none 0 PI-1 n. z. b. 84.6 M-6-2 I-2 250 PI-1 n. z. b. 94.0 M-6-3 I-2 500 PI-1 n. z. b. 93.0 Table 6d Mixture H-6 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM [Ppm] [%] M-6-1 none 0 PI-1 n. z. b. - M-6-2 I-2 250 PI-1 n. z. b. +11.1 M-6-3 I-2 500 PI-1 n. z. b. +10.5

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntes, nzb: to be determined

Example 7:

The mixture H-7 is examined as described in the previous examples.

Tabelle 7a Mischung H-7 Bsp. Stabilisator c (Stab) PI HR (100°C/60 Hz/1 V) [ppm] [%] Anfangswert 30 min Suntest M-7-1 Keiner 0 PI-1 58,0 57,5 M-7-2 I-2 250 PI-1 67,1 70,1 Tabelle 7b Mischung H-7 Bsp. Stabilisator c (Stab) PI (HR_Sn/HR_In) – 1 FoM [ppm] [%] M-7-1 Keiner 0 PI-1 –0,8 - M-7-2 I-2 250 PI-1 +4,4 +21,9 Good results are also achieved with this example, and Suntest's Figure of Merit shows a clear stabilization of almost 22% compared to the reference.

Table 7a Mixture H-7 Ex. stabilizer c (staff) PI HR (100 ° C / 60 Hz / 1 V) [Ppm] [%] initial value 30 min Suntest M-7-1 none 0 PI-1 58.0 57.5 M-7-2 I-2 250 PI-1 67.1 70.1 Table 7b Mixture H-7 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM [Ppm] [%] M-7-1 none 0 PI-1 -0.8 - M-7-2 I-2 250 PI-1 +4.4 +21.9

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntest

Example 8:

The mixture H-8 is examined as described in the previous examples.

Tabelle 8a Mischung H-8 Bsp. Stabilisator c (Stab) PI HR (100°C/60 Hz/1 V) [ppm] [%] Anfangswert 30 min Suntest M-8-1 Keiner 0 PI-1 56,0 50,2 M-8-2 I-2 300 PI-1 70,4 69,3 Tabelle 8b Mischung H-8 Bsp. Stabilisator c (Stab) PI (HR_Sn/HR_In) – 1 FoM [ppm] [%] M-8-1 Keiner 0 PI-1 –10,3 - M-8-2 I-2 300 PI-1 –1,5 +38,0 Also in this example very good results are achieved and the figure of merit has a significant stabilization of 38%, compared to the reference.

Table 8a Mixture H-8 Ex. stabilizer c (staff) PI HR (100 ° C / 60 Hz / 1 V) [Ppm] [%] initial value 30 min Suntest M-8-1 none 0 PI-1 56.0 50.2 M-8-2 I-2 300 PI-1 70.4 69.3 Table 8b Mixture H-8 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM [Ppm] [%] M-8-1 none 0 PI-1 -10.3 - M-8-2 I-2 300 PI-1 -1.5 +38.0

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntest

Example 9:

The mixture H-9 is tested as described in the previous examples, in test cells with PI-1 and PI-3. The HR measurements in the Tes cells with PI-3 were examined at RT, 10 Hz and 1 V as indicated in the table.

Tabelle 9a Mischung H-9 Bsp. Stabilisator c (Stab) PI HR (100°C/60 Hz/1 V) [ppm] [%] Anfangswert 30 min Suntest M-9-1 Keiner 0 PI-1 56,1 43,7 M-9-2 I-2 300 PI-1 67,8 64,0 Tabelle 9b Mischung H-9 Bsp. Stabilisator c (Stab) PI (HR_Sn/HR_In) – 1 FoM [ppm] [%] M-9-1 Keiner 0 PI-1 –22,1 - M-9-2 I-2 300 PI-1 –5,6 +46,4 Very good results are also obtained in this example and the Figure of Merit shows a clear stabilization compared to the reference for PI-1 with 46% as well as for PI-2 with more than 11%.

Table 9a Mixture H-9 Ex. stabilizer c (staff) PI MR (100 ° C / 60 Hz / 1 V) [Ppm] [%] initial value 30 min Suntest M-9-1 none 0 PI-1 56.1 43.7 M-9-2 I-2 300 PI-1 67.8 64.0 Table 9b Mixture H-9 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM [Ppm] [%] M-9-1 none 0 PI-1 -22.1 - M-9-2 I-2 300 PI-1 -5.6 +46.4

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntest

Table 9c Mixture H-9 Ex. stabilizer c (staff) PI MR (RT / 10 Hz / 1 V) [Ppm] [%] initial value 30 min Suntest M-9-3 none 0 PI-3 n. z. b. 80.0 M-9-4 I-2 300 PI-3 n. z. b. 89.4 Table 9d Mixture H-9 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM [Ppm] [%] M-9-3 none 0 PI-3 n. z. b. - M-9-4 I-2 300 PI-3 n. z. b. -

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntest, nzb: to be determined

Example 10:

The mixture H-10 is tested as described in the previous examples, in test cells with PI-1 and PI-3. The HR measurements in the Tes cells with PI-3 were assayed at RT, 10 Hz and 1 V as indicated in the table.

Tabelle 10a Mischung H-10 Bsp. Stabilisator c (Stab) PI HR (100°C/60 Hz/1 V) [ppm] [%] Anfangswert 30 min Suntest M-10-1 Keiner 0 PI-1 57,2 44,4 M-10-2 I-2 300 PI-1 71,2 67,1 Tabelle 10b Mischung H-10 Bsp. Stabilisator c (Stab) PI (HR_Sn/HR_In) – 1 FoM [ppm] [%] M-10-1 Keiner 0 PI-1 –22,1 - M-10-2 I-2 300 PI-1 –5,6 +51,1 Good results are also obtained in this example and the Figure of Merit shows a clear stabilization over the reference for PI-1 with over 50% as well as for PI-3 with more than 12%.

Table 10a Mixture H-10 Ex. stabilizer c (staff) PI MR (100 ° C / 60 Hz / 1 V) [Ppm] [%] initial value 30 min Suntest M-10-1 none 0 PI-1 57.2 44.4 M-10-2 I-2 300 PI-1 71.2 67.1 Table 10b Mixture H-10 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM [Ppm] [%] M-10-1 none 0 PI-1 -22.1 - M-10-2 I-2 300 PI-1 -5.6 +51.1

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntest

Table 10c Mixture H-10 Ex. stabilizer c (staff) PI MR (RT / 10 Hz / 1 V) [Ppm] [%] initial value 30 min Suntest M-10-3 none 0 PI-3 n. z. b. 80.0 M-10-4 I-2 300 PI-3 n. z. b. 90.2 Table 10d Mixture H-10 Ex. stabilizer c (staff) PI (HR _Sn / HR _In ) - 1 FoM [Ppm] [%] M-10-3 none 0 PI-3 n. z. b. - M-10-4 I-2 300 PI-3 n. z. b. +12.7

Remarks:

• HR _Sn : HR _SUN , HR _In : HR _Initial and FoM: Figure of merit after Suntest, nzb: to be determined

Further examples:

In the further examples, the host mixtures H11-H19 are investigated analogously to the preceding examples. All mixtures show by the inventive use a significant stabilization on planar orientation layers relative to the reference.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

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• DE 102011008687 A1 [0018]
• EP 2182046 A1 [0020]
• WO 2008/009417 A1 [0020]
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• WO 2009/115186 A1 [0020]
• JP 55-023169A [0022]
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Claims (15)

Liquid crystal (FK) display comprising an FK cell consisting of two substrates, wherein at least one substrate is translucent and at least one substrate has a planar orientation layer and control electrodes, and a layer of FK medium with negative dielectric anisotropy located between the substrates, characterized in that the FK display is a compound of the formula I:

wherein I is an integer of 2 to 26 contains. FK display according to claim 1, characterized in that it is an IPS (in-plane switching) or FFS (fringe field switching) or Polymer Stabilized (PS) -IPS or PS-FFS display. Use of compounds of the formula

wherein I is an integer of 2 to 26, defined in FK displays as in one or more of claims 1-2. Use of compounds of the formula I according to claim 3, characterized in that the total concentration of the compounds of the formula I, in the total FK medium is between 1 ppm or more to 2,000 ppm or less, and I 8 to 20. Use of compounds of the formula I according to claim 4, characterized in that the FK medium has a dielectric anisotropy of ≤ -3.5. Use of compounds of the formula I according to claim 5, characterized in that the FK medium has a dielectric anisotropy of ≤ -4.4. Use of compounds of the formula I according to any one of claims 3-5, characterized in that the LC medium is a compound of the formula II

wherein R ^{21 is} an unsubstituted alkyl radical having 1 to 5 C atoms, or an unsubstituted alkenyl radical having 2 to 5 C atoms, R ^{22 is} an unsubstituted alkenyl radical having 2 to 5 carbon atoms, in a concentration of ≥ 20%, preferably ≥ 25%, more preferably ≥ 30%. Use of compounds of the formula I according to Claim 7, characterized in that the LC medium additionally comprises one or more compounds selected from the group of the compounds of the formulas III and IV

in which, independently of one another, R ^{31 is} an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkyloxy radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, or an unsubstituted cycloalkyl radical having 3 to 7 C atoms Atoms, R ^{32 is} an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkyloxy radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, R ^{41 is} an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, R ⁴² an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkyloxy radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms,

and

independent on each occurrence

independent on each occurrence

one of Z ⁴¹ and Z ^{42 is} -CH ₂ -CH ₂ -, -CH = CH-, -CH ₂ -O-, -O-CH ₂ -, -CF ₂ -O- or -O-CF ₂ - and the other -CH ₂ -CH ₂ -, -CH = CH-, -CH ₂ -O-, -O-CH ₂ -, -CF ₂ -O-, -O-CF ₂ - or a single bond, m and n each independently of one another 0, 1 or 2, (m + n) 0, 1, 2, or 3, p and q are each independently 0, 1 or 2, and (p + q) 1, 2, or 3. Use of compounds of the formula I according to Claim 8, characterized in that the LC medium comprises one or more compounds of the formula III or IV selected from the group of the compounds of the formulas III-1 to III-7 and IV-1 to IV-4 .

wherein the parameters have the respective meanings given in claim 7. Use of compounds of the formula I according to Claim 9, characterized in that the LC medium comprises one or more compounds of the formula V and / or of the formula VI,

wherein R ⁵¹ and R ⁵² independently of one another have the meaning given for R ³¹ and R ³² , and preferably alkyl having 1 to 7 C atoms, preferably n-alkyl, particularly preferably n-alkyl having 1 to 5 C atoms, alkoxy with 1 to 7 C atoms, preferably n-alkoxy, particularly preferably n-alkoxy having 2 to 5 C atoms, alkoxyalkyl, alkenyl or alkenyloxy having 2 to 7 C atoms, preferably having 2 to 4 C atoms, preferably alkenyloxy,

to

if available, each independently

Z ⁵¹ to Z ^{53 are} each independently of one another -CH ₂ -CH ₂ -, -CH ₂ -O-, -CH = CH-, -C≡C-, -COO- or a single bond, preferably -CH ₂ -CH ₂ - , -CH ₂ -O- or a single bond and particularly preferably a single bond, i and j are each independently 0 or 1, R ^{61 is} an unsubstituted alkyl radical having 1 to 7 C atoms or preferably an n-alkyl radical, particularly preferably 2, 3, 4 or 5 carbon atoms, and R ^{62 is} an unsubstituted alkyl radical having 1 to 7 carbon atoms or an unsubstituted alkoxy radical having 1 to 6 carbon atoms, both preferably having 2 to 5 carbon atoms. FK medium which has a dielectric anisotropy of ≦ -6.0 to ≦ -4.5, comprising, at least one compound of the formula I according to claim 1 and at least one further liquid-crystalline component. FK medium according to claim 11, characterized in that the LC medium contains a compound of the formula II according to claim 6 and a further compound of the formula III or formula IV according to claim 7. A process for the preparation of an LC medium according to claim 11 or 12, wherein one or more compounds of formula I with one or more liquid crystalline compounds II to IV as defined in one or more of claims 6 to 9, and optionally with one or more others liquid crystalline compounds and / or polymerizable compounds and / or additives. Method for stabilizing an LC medium according to claim 11 or 12, characterized in that one proceeds as described in claim 13. A method of stabilizing an LC display by using an LC medium according to any one of claims 11 or 12 in the LC display.