CN112218933A

CN112218933A - Compound and liquid-crystalline medium

Info

Publication number: CN112218933A
Application number: CN201980036225.3A
Authority: CN
Inventors: A·格特兹; S·玛格; R·弗尔特
Original assignee: Merck Patent GmbH
Current assignee: Merck Patent GmbH
Priority date: 2018-05-30
Filing date: 2019-05-27
Publication date: 2021-01-12
Also published as: TW202006121A; TWI833759B; WO2019228939A1; EP3802732A1; KR20210015933A

Abstract

The invention relates to compounds of formula (I), and preferably liquid-crystalline media having a nematic phase and a negative dielectric anisotropy, comprising a) one or more compounds of formula (I)

And b) one or more compounds selected from the group consisting of compounds of the formulae (II) and (III)

Description

Compound and liquid-crystalline medium

The present invention relates to novel compounds, in particular for liquid-crystalline media, but also to the use of these liquid-crystalline media in liquid-crystal displays, and to these liquid-crystal displays, in particular liquid-crystal displays using the ECB (electrically controlled birefringence) effect with dielectrically negative liquid crystals in the homeotropic initial alignment. The liquid-crystalline media according to the invention are distinguished by particularly short response times in the displays according to the invention, at the same time by a high voltage holding ratio (VHR or also just HR for short).

The principle of electrically controlled birefringence, the ECB effect or the DAP (aligned phase distortion) effect was first described in 1971 (m.f. schieckel and k.fahrenschon, "Deformation of biological liquid crystals with vertical orientation in electrical fields", appl.phys.lett.19(1971), 3912). Followed by papers from j.f. kahn (appl.phys.lett.20(1972),1193) and g.labrunie and j.robert (j.appl.phys.44(1973), 4869).

The papers of J.Robert and F.Clerc (SID 80Digest techn. papers (1980),30), J.Duchene (Displays 7(1986),3) and H.Schad (SID 82Digest techn. papers (1982),244) have shown that the liquid crystal phase must have a high value of the ratio of the elastic constants, K₃/K₁High values of optical anisotropy Deltan and dielectric anisotropy values of Deltaepsilon ≦ -0.5 for high information display elements based on the ECB effect. Electro-optical display elements based on the ECB effect have a homeotropic edge alignment (VA technique, also referred to as vertical alignment, or VAN, vertical alignment nematic). Dielectrically negative liquid-crystalline media can also be used in displays using the so-called IPS (in-plane switching) effect.

Industrial application of this effect in electro-optical display elements requires LC phases which have to meet a wide variety of requirements. Of particular importance here are chemical resistance to moisture, air and physical influences such as radiation in the thermal, infrared, visible and ultraviolet regions and also direct and alternating electrical fields.

Furthermore, it is desirable that the industrially usable LC phase has a liquid crystalline mesophase in a suitable temperature range and a low viscosity.

None of the series of compounds having a liquid crystalline mesophase disclosed so far includes a single compound that satisfies all of these requirements. Thus, in general, mixtures of 2 to 25, preferably 3 to 18, compounds are prepared in order to obtain substances which can be used as LC phases.

Matrix liquid crystal displays (MLC displays) are known. Non-linear elements that can be used for independent switching of individual pixels are, for example, active elements (i.e., transistors). The term "active matrix" is then used, wherein in general Thin Film Transistors (TFTs) are used, which are usually arranged on a glass plate as substrate.

A distinction is made between two techniques: TFTs comprising compound semiconductors (e.g. CdSe) or TFTs based on polycrystalline and especially amorphous silicon. The latter technology is currently of greatest commercial importance worldwide.

The TFT matrix is disposed on the inside of one glass plate of the display, while the other glass plate carries a transparent counter electrode on its inside. The TFT is very small compared to the size of the pixel electrode and has almost no adverse effect on the image. The technique can also be extended to full colour displays where mosaic (mosaic) of red, green and blue filters are arranged in such a way that the filter elements are located with respect to each switchable pixel.

TFT displays most used so far are typically operated with crossed polarizers in transmission and are backlit. For TV applications, IPS cells or ECB (or VAN) cells are used, whereas monitors typically use IPS cells or TN (twisted nematic) cells, and notebook, laptop and mobile applications typically use TN cells.

The term MLC display here covers any matrix display with integrated non-linear elements, i.e. in addition to an active matrix also displays with passive elements, for example varistors or diodes (MIM ═ metal-insulator-metal).

MLC displays of this type are suitable in particular for TV applications, monitors and notebooks, or for displays with a high information density, for example in automobile construction or aircraft construction. In addition to problems with respect to the angle dependence of the contrast and the response time, MLC displays also suffer from problems due to an insufficiently high specific resistance of the liquid-crystal mixture [ TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K., TAJIMA, E., WATANABE, H., SHIMIZU, H., Proc. Eurodisplay 84, Sept.1984: A210-one 288Matrix LCD Controlled by Double Stauble Stadiode Rings, pp.141ff., Paris; STROMER, M., Proc. Eurodisplay 84, Sept.1984: Design of Thin Film Transistors for Matrix Addressing of Television Liquid Crystal Displays, pp.145ff., Paris ]. As the resistance decreases, the contrast of the MLC display deteriorates. The specific resistance of the liquid crystal mixture generally decreases over the life of an MLC display due to interaction with the inner surfaces of the display, and a high (initial) resistance is therefore very important for displays which must have an acceptable resistance value over long periods of operation.

In addition to IPS displays (e.g. Yeo, S.D., paper 15.3: "An LC Display for the TV Application", SID 2004International Symposium, Digest of Technical Papers, XXXV, volume II, pages 758 and 759) and the long-known TN displays, displays using the ECB effect, so-called VAN (vertically aligned nematic) displays, have been recognized as one of the three newer types of liquid crystal displays which are currently most important, in particular for television applications.

The most important designs that can be mentioned here are: MVA (multi-domain vertical alignment type, e.g., Yoshide, H.et al, paper 3.1: "MVA LCD for Notebook or Mobile PCs.", SID 2004International Symposium, Digest of Technical Papers, XXXV, volume I, pages 6 to 9, and Liu, C.T. et al, paper 15.1: "A46-inch TFT-LCD HDTV Technology …", SID 2004International Symposium, Digest of Technical Papers, XXXV, volume II, pages 750 to 753), PVA (patterned vertical alignment type), e.g.: kim, Sang Soo, article 15.4: "Super PVA Sets New State-of-the-Art for LCD-TV", SID 2004International Symposium, Digest of Technical Papers, XXXV, volume II, pages 760 to 763) and ASV (advanced Super View, e.g.: shigeta, Mitzuhiro and Fukuoka, Hirofumi, paper 15.2 "Development of High Quality LCDTV", SID 2004International Symposium, Digest of Technical Papers, XXXV, volume II, pages 754 to 757).

In general form, this technique is compared in, for example, Souk, Jun, SID Seminar 2004, Seminar M-6, "Recent Advances in LCD Technology", Seminar features Notes, M-6/1 to M-6/26, and Miller, Ian, SID Seminar 2004, Seminar M-7, "LCD-tension", Seminar features Notes, M-7/1 to M-7/32. Although the response time of modern ECB displays has been significantly improved by overdrive (over drive) addressing methods, for example: kim, Hyeon Kyeong et al, article 9.1, "A57-in. wide UXGA TFT-LCD for HDTV Application", SID 2004International Symposium, digest t of Technical Papers, XXXV, volume I, pages 106 to 109, but the realization of video compatibility response times, especially in greyscale switching, is still a problem that has not been solved to a satisfactory extent.

ECB displays, like ASV displays, use liquid-crystalline media with a negative dielectric anisotropy (Δ ∈), whereas TN and up to now all conventional IPS displays use liquid-crystalline media with a positive dielectric anisotropy.

In this type of liquid crystal display, liquid crystals are used as dielectrics, the optical properties of which change reversibly upon application of a voltage.

Since in displays in general, i.e. also in displays according to these mentioned effects, the operating voltage should be as low as possible, liquid-crystalline media are used which are usually composed mainly of liquid-crystalline compounds which all have the same sign of the dielectric anisotropy and have the highest possible value of the dielectric anisotropy. In general, at most a relatively small proportion of neutral compounds is used, and if possible no compounds having the opposite sign of the dielectric anisotropy to the medium are used. In the case of liquid-crystalline media with negative dielectric anisotropy for ECB displays, compounds with negative dielectric anisotropy are therefore predominantly used. The liquid-crystalline medium used generally consists predominantly and usually even essentially of liquid-crystalline compounds having a negative dielectric anisotropy.

In the media used according to the application, usually at most significant amounts of dielectrically neutral liquid-crystalline compounds are used and usually only very small amounts of dielectrically positive compounds or even no dielectrically positive compounds are used, since in general liquid-crystal displays are intended to have the lowest possible addressing voltage.

The known liquid-crystalline media are not sufficiently stable for many practical applications in liquid-crystal displays. In particular, their stability to irradiation with UV and even with conventional backlighting leads to impairment, in particular of the electrical properties. Thus, for example, the conductivity is significantly increased.

The use of so-called "hindered amine light stabilizers", abbreviated to HALS, has been proposed for the stabilization of liquid crystal mixtures.

For example, it is proposed in WO 2009/129911A 1 and WO 2012/076105A 1 to include small amounts

770 nematic liquid crystal mixtures having negative dielectric anisotropy and using as stabilizers compounds of the formula

However, the corresponding liquid-crystal mixtures do not have sufficient properties for some practical applications. In particular, they are not sufficiently stable for irradiation using typical CCFL (cold cathode fluorescent lamp) and especially typical modern LED (light emitting diode) backlights.

Similar liquid crystal mixtures are also known, for example, from EP 2182046 a1, WO 2008/009417 a1, WO 2009/021671 a1 and WO 2009/115186 a 1. However, the use of stabilizers is not indicated in these documents.

According to the disclosure of these documents, these liquid-crystal mixtures may optionally also comprise various stabilizers, for example phenols and sterically hindered amines (hindered amine light stabilizers, HALS for short). However, these liquid-crystal mixtures are characterized by a relatively high threshold voltage and at best by mediocre stability. In particular, their voltage holding ratio decreases after exposure. Furthermore, the discoloration of the yellowish color is generally increased.

The use of various stabilizers in liquid-crystalline media is described, for example, in JP (S)55-023169(A), JP (H)05-117324(A), WO 02/18515A 1 and JP (H)09-291282 (A).

In particular, EP 2993216A 1 proposes stable compounds of the formula

In addition to other various as secondary stabilizers and in addition to nitrogen heterocyclic substances, WO 2009/129911A 1 also suggests stabilized compounds of the formula

EP 2514800A 2 proposes the use of compounds of the formula for the stabilization of liquid-crystalline media

Wherein R is¹¹Among other meanings, o or OH may be substituted instead of H. However, the chemical stability of these compounds with respect to hydrolysis and in particular their solubility in liquid-crystalline media is in most cases inadequate for practical applications.

WO 2016/146245A 1 proposes compounds of the formula for stabilization purposes in liquid-crystalline media.

DE 2016005083A 1 also proposes the use of the above-mentioned compounds and compounds of the formula

However, the chemical stability, in particular with regard to hydrolysis, and especially the solubility in liquid-crystalline media, is in most cases inadequate for practical use.

The unpublished application DE 102016009485.0, on the other hand, proposes ether-linked compounds of the formula as stabilizers for liquid-crystal mixtures.

The prior art liquid-crystalline media with correspondingly low addressing voltages have relatively low resistance values or low VHR and often lead to undesirable flicker and/or insufficient transmission in the display. Furthermore, they are not sufficiently stable to thermal/UV exposure, which is necessary for low addressing voltages, at least if they have a correspondingly high polarity.

On the other hand, the addressing voltage of prior art displays with high VHR is often too high, especially for displays that are not directly or continuously connected to the power supply network, for example for displays for mobile applications.

Furthermore, the phase range of the liquid crystal mixture must be sufficiently wide for the intended application of the display. Therefore, the low temperature storage at-30 ℃ in the box and preferably in bulk (in bulk) should be 240 hours or more.

The response time of the liquid-crystalline medium in the display must be improved, i.e. reduced. This is especially important for displays used for television or multimedia applications. In order to improve the response time, it has been repeatedly proposed in the past to optimize the rotational viscosity (γ) of the liquid-crystalline medium₁) I.e. to achieve a medium with the lowest possible rotational viscosity. However, the results achieved here are not sufficient for many applications and, therefore, make it desirable to find additional optimization methods.

Sufficient stability of the medium to extreme loads, especially to UV exposure and heat, is of particular importance. This is particularly difficult for simultaneously optimizing the rotational viscosity. This may be important especially in the case of applications in mobile devices, such as displays in mobile phones, since in particular in these devices it is preferred to use a relatively low addressing frequency.

The disadvantages of the MLC displays disclosed to date are due to their comparatively low contrast, the relatively high viewing-angle dependence and the difficulty of grey scale generation in these displays, as well as their inadequate VHRs and their inadequate lifetimes.

Therefore, there is still a great need for MLC displays having very high specific resistance, at the same time having a large operating temperature range, short response times and low threshold voltages, by means of which various gray levels can be generated, in particular having good and stable VHRs.

It is an object of the present invention to provide MLC displays not only for monitor and TV applications, but also for mobile telephones and navigation systems, which are based on the ECB, IPS or FFS (edge field effect) effect, as described in Lee, s.h., Lee, s.l.and Kim, h.y. "Electro-optical characteristics and switching principle of a novel liquid crystal controlled by way of field switching", appl.phys.letters, vol.73, No.20, pp.2881-2883(1998), do not have the disadvantages indicated above, or only to a lesser extent do so, and at the same time have very high specific resistance values. In particular, for mobile phones and navigation systems it must be ensured that they also operate at extremely high and low temperatures.

Surprisingly, it has been found that liquid-crystal displays, in particular FFS displays, which have a low threshold voltage and short response times and at the same time a sufficiently broad nematic phase, advantageously a relatively low birefringence (. DELTA.n), good stability to decomposition by heat and by UV exposure, good solubility and a stable and high VHR can be achieved when nematic liquid-crystal mixtures comprising at least one compound of the formula I and in each case at least one compound of the formula II, preferably of the sub-formula II-1, and/or at least one compound selected from the group consisting of the compounds of the formulae III-1 to III-4, preferably of the formula III-2 and/or B are used in these display elements.

This type of medium can be used for electro-optical displays with active matrix addressing, in particular based on the ECB effect, and for IPS displays and for FFS displays.

The present invention therefore relates to liquid-crystalline media based on mixtures of polar compounds, comprising at least one compound of the formula I and at least one compound comprising one or more compounds of the formula II and preferably additionally one or more compounds selected from the group consisting of the compounds of the formulae III-1 to III-4 and/or the compounds of the formula B.

The mixtures according to the invention exhibit a very broad nematic phase range with a clearing point of > 70 ℃, very favourable values for the capacitance threshold, relatively high values for the retention and at the same time good low-temperature stability at-20 ℃ and-30 ℃ and very low rotational viscosity. The mixtures according to the invention are further characterized by a very good ratio of clearing point to rotational viscosity and by a high negative dielectric anisotropy.

It has surprisingly been found that liquid-crystalline media with a suitably high Δ ∈, a suitable phase range and Δ n can be achieved which do not have the disadvantages of the prior art materials or at least do so to a significantly reduced extent.

It has now surprisingly been found that the compounds of the formula I even when used alone without further heat stabilizers lead to notable, in many cases sufficient, liquid-crystalline mixtures being exposed to UV lightAnd stabilization against heat. This is the case in particular in most cases where the parameter p in the compounds of the formula I used represents 2 and n × p represents 4 or 6. In one embodiment of the present invention, compounds of the formula I in which p denotes 2 and n denotes 3 or 4 are therefore particularly preferred, and the use of these compounds in the liquid-crystal mixtures according to the invention is also particularly preferred. Preference is likewise given to the radical-Z therein¹¹-S¹¹-Z¹²-represents an omega-dioxyalkylene group, i.e. -O-S¹¹-O-of the formula I.

However, sufficient stabilization of the liquid-crystal mixtures with respect to UV exposure and with respect to heat can also be achieved, in particular in the case that one or more further compounds, preferably phenolic stabilizers, are present in the liquid-crystal mixture in addition to one or more compounds of the formula I. These other compounds are suitable as heat stabilizers.

The present invention therefore relates to compounds of the formula I and to liquid-crystalline media having a nematic phase and a negative dielectric anisotropy, comprising

a) One or more compounds of the formula I, preferably in a concentration of from 1ppm to 2500ppm, preferably to 2000ppm, preferably to 1500ppm, particularly preferably to 1000ppm, preferably in the range from 1ppm to 500ppm, particularly preferably in the range from 1ppm to 250ppm,

wherein

R¹¹Each occurrence independently of the others represents H, F, a linear or branched alkyl chain having 1 to 20C atoms, one of which is-CH₂-a group or, if present, a plurality of-CHs₂The radical-may be replaced by-O-or-C (═ O) -but no two adjacent-CH groups₂The radical being replaced by-O-, and one or, if present, more than one-CH₂The radicals-CH-OR-C.ident.C-may be replaced by-CH-OR-C.ident.C-and one OR more H atoms may be replaced by F, OR¹³,N(R¹³)(R¹⁴) Or R¹⁵Instead of this, the user can,

R¹¹preferred expression(s)H or alkyl, particularly preferably n-alkyl and very particularly preferably n-butyl,

R¹²each occurrence independently of the others represents a straight or branched alkyl chain having 1 to 20C atoms, one of which is-CH₂A group or a plurality of-CH₂The radical-may be replaced by-O-or-C (═ O) -but no two adjacent-CH groups₂The radical being replaced by-O-, a hydrocarbon radical comprising cycloalkyl or alkylcycloalkyl units, and in which one-CH₂A group or a plurality of-CH₂The radicals-may be replaced by-O-or-C (═ O) -without two adjacent-CH groups₂The radical being replaced by-O-, and one OR more H atoms being able to be replaced by F, OR¹³,N(R¹³)(R¹⁴) Or R¹⁵Instead of, OR in addition to, aromatic OR heteroaromatic hydrocarbon radicals in which one OR more H atoms may be replaced by F, OR¹³,N(R¹³)(R¹⁴) Or R¹⁵Instead of this, the user can,

R¹²preferably represents H, unbranched alkyl or branched alkyl, particularly preferably H or unbranched alkyl,

R¹³each occurrence independently of the others represents a straight-chain or branched alkyl or acyl radical having 1 to 10C atoms, preferably an n-alkyl radical, or an aromatic hydrocarbon radical having 6 to 12C atoms or a carboxylic acid radical,

R¹⁴each occurrence independently of the others represents a straight-chain or branched alkyl or acyl radical having 1 to 10C atoms, preferably an n-alkyl radical, or an aromatic hydrocarbon radical having 6 to 12C atoms or a carboxylic acid radical,

R¹⁵each occurrence independently of the other represents a linear or branched alkyl group having 1 to 10C atoms, one of which is-CH₂A group or a plurality of-CH₂The radicals-may be replaced by-O-or-C (═ O) -without two adjacent-CH groups₂The radical-is replaced by-O-,

S¹¹and S¹²Each occurrence independently of the other denotes an alkylene radical having 1 to 20C atoms, which is branched or, preferably, straight-chain, - (CH) having preferably 1 to 20C atoms, preferably 1 to 10C atoms, particularly preferably 1 to 8C atoms₂-)_nOne of them is-CH₂-a group or, if present, a plurality of-CHs₂The radicals-may be replaced by-O-or-C (═ O) -without two adjacent-CH groups₂The radical being replaced by-O-, and one or, if present, more than one-CH₂The radicals-CH-OR-C.ident.C-may be replaced by-CH-OR-C.ident.C-and one OR more H atoms may be replaced by F, OR¹³,N(R¹³)(R¹⁴) Or R¹⁵Instead of, or in addition to, a single bond, X¹¹The expression C is shown in the specification,

Y¹¹to Y¹⁴Independently of one another, each represents methyl or ethyl, particularly preferably both represent methyl or ethyl and very particularly preferably methyl,

Z¹¹to Z¹⁴Independently of one another, each occurrence represents-O-, -C-O-O-, -C-O-, -O- (C-O) -O-, -N-R¹³)-,-N-R¹³- (C ═ O) -or if S¹¹Is a single bond, but Z represents a single bond¹¹And Z¹²Both do not represent-O-simultaneously, and, however, if S is¹²Is a single bond, Z¹³And Z¹⁴Both are not simultaneously-O-, and, however, if-X¹¹[-R¹¹]_o-is a single bond, Z¹²And Z¹³The two are not simultaneously-O-,

Z¹¹preferably represents-O-,

Z¹³preferably represents a single bond, and preferably represents,

n p represents an integer from 3 to 10, preferably to 8,

p represents a number of 1 or 2,

o represents (3-p),

in the case where p is 1,

n represents 3,4,5, 6 or 8, particularly preferably 4,6 or 8, very particularly preferably 4 or 6, and,

m represents (10-n), and,

in the case where p is 2,

n represents an integer from 2 to 4, preferably 2 or 3, particularly preferably 3, and

m represents (4-n), and

denotes an organic radical having (m + n) binding sites, preferably an alkanediyl, alkanetriyl or alkanetetrayl unit having 4 binding sites, preferably having 1 to 30C atoms, where in addition to m radicals R present in the molecule¹²Furthermore, but independently thereof, one other H atom may be replaced by R¹²Instead of or in addition to one or more other H atoms, may be replaced by R¹²Instead, preference is given to having a mono-or bivalent alkanetetrayl unit on each terminal C atom, in which one-CH₂A group or a plurality of-CH₂The radicals-may be replaced by-O-or- (C ═ O) -in such a way that the two-O-atoms are not bonded directly to one another, or substituted or unsubstituted aromatic or heteroaromatic hydrocarbon radicals having a valency of up to 10, where the radicals R are present in the molecule in addition to m radicals R¹²Furthermore, but independently thereof, one other H atom may be replaced by R¹²Instead of or in addition to one or more other H atoms, may be replaced by R¹²Instead of this, the user can,

and-X in case p ═ 1¹¹[-R¹¹]_o-alternatively may also represent a single bond, and

b) one or more compounds selected from the group consisting of compounds of formulae II and III, preferably being dielectrically positive, preferably having a dielectric anisotropy of each 3 or more:

wherein

R²Represents H, a non-fluorinated or fluorinated alkyl group or a non-fluorinated or fluorinated alkoxy group having 1 to 17C atoms, or a non-fluorinated or fluorinated alkenyl group having 2 to 15C atoms, a non-fluorinated or fluorinated alkenyloxy group or a non-fluorinated or fluorinated alkoxyalkyl group, wherein one or more CH are₂The radicals may be

Instead, preference is given to alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 carbon atoms, alkenyl having 2 to 7 carbon atoms, alkenyloxy,alkoxyalkyl groups or fluorinated alkenyl groups, and preferably alkyl or alkenyl groups,

represent independently of each other at each occurrence

Wherein R is^LRepresent, identically or differently on each occurrence, H or an alkyl radical having 1 to 6C atoms, or

Preferably

More preferably

L²¹And L²²Independently of one another, H or F, preferably L²¹The expression "F" is used to indicate that,

X²represents halogen, haloalkyl having 1 to 3C atoms, or alkoxy or has 2 or 3Halogenoalkenyl or alkenyloxy having a C atom, preferably F, Cl, -OCF₃，-O-CH₂CF₃，-O-CH＝CH₂，-O-CH＝CF₂or-CF₃Very particular preference is given to F, Cl, -O-CH ═ CF₂or-OCF₃M represents 0,1,2 or 3, preferably 1 or 2, and particularly preferably 1,

R³has the pair R²One or more of the meanings given for H, an unfluorinated or fluorinated alkyl or unfluorinated or fluorinated alkoxy group having 1 to 17 carbon atoms or an unfluorinated or fluorinated alkenyl group having 2 to 15C atoms, an unfluorinated or fluorinated alkenyloxy group or an unfluorinated or fluorinated alkoxyalkyl group wherein one or more CH's are present₂The radicals may be

Instead, an alkyl group, an alkoxy group, a fluorinated alkyl group or a fluorinated alkoxy group having 1 to 7 carbon atoms, an alkenyl group, an alkenyloxy group, an alkoxyalkyl group or a fluorinated alkenyl group having 2 to 7 carbon atoms is preferred, and an alkyl group or an alkenyl group is preferred,

independently of one another at each occurrence the above

One of the meanings given and preferably

More preferably

L³¹And L³²Independently of one another, H or F, preferably L³¹The expression "F" is used to indicate that,

X³represents halogen, haloalkyl or alkoxy having 1 to 3C atoms or haloalkenyl or alkenyloxy having 2 or 3C atoms, preferably F, Cl, -OCF₃，-OCHF₂，-O-CH₂CF₃，-O-CH＝CF₂，-O-CH＝CH₂or-CF₃Very particular preference is given to F, Cl, -O-CH ═ CF₂，-OCHF₂or-OCF₃，

Z³represents-CH₂CH₂-，-CF₂CF₂-, -COO-, trans-CH-, trans-CF-, -CH₂O-or a single bond, preferably-CH₂CH₂-, -COO-, trans-CH-or a single bond and very preferably-COO-, trans-CH-or a single bond, and

n represents 0,1,2 or 3, preferably 1,2 or 3 and particularly preferably 1, and

c) optionally one or more compounds selected from compounds of formulae IV and V, preferably dielectrically neutral:

wherein

R⁴¹And R⁴²Independently of one another, have the above for R under formula II²Given meanings, preferably R⁴¹Represents alkyl and R⁴²Represents alkyl or alkoxy or R⁴¹Represents alkenyl and R⁴²Represents an alkyl group, and is represented by,

independently of each other and if

Two occurrences, then these are also independent of each otherThe ground has the above

One of the meanings given and preferably denotes

Preference is given to

Is represented by one or more of

Z⁴¹And Z⁴²Independently of each other and if Z⁴¹Two occurrences, then these also represent independently of one another-CH₂CH₂-, -COO-, trans-CH-, trans-CF-, -CH₂O-，-CF₂O-, -C.ident.C-or a single bond, preferably one or more thereof represents a single bond, and

p represents 0,1 or 2, preferably 0 or 1,

R⁵¹and R⁵²Independently of one another have the formula for R⁴¹And R⁴²One of the meanings given and preferably denotes alkyl having 1 to 7 carbon atoms, preferably n-alkyl, particularly preferably n-alkyl having 1 to 5 carbon atoms, alkoxy having 1 to 7 carbon atoms, preferably n-alkoxy, particularly preferably n-alkoxy having 2 to 5 carbon atoms, alkoxyalkyl having 2 to 7C atoms, preferably having 2 to 4C atoms, alkenyl or alkenyloxy, preferably alkenyloxy,

to

If present, each independently of the other, have the above pairs

One of the meanings given and preferably denotes

Preference is given to

Preference is given to

To represent

And, if present

Preferred expression(s)

Z⁵¹To Z⁵³Each independently of the other represents-CH₂-CH₂-，CH₂-O-, -CH ≡ CH-, -C ≡ C-, -COO-or a single bond, preferably-CH-, -C ≡ C-, -COO-or a single bond₂-CH₂-，-CH₂-O-or a single bond, and particularly preferably a single bond,

i and j each independently of the other represent 0 or 1,

(i + j) preferably represents 0,1 or 2, more preferably 0 or 1, and most preferably 1,

d) again optionally, alternatively or additionally, one or more compounds selected from compounds of formulae VI to IX, preferably dielectrically negative:

wherein

R⁶¹，R⁶²，R⁷¹，R⁷²，R⁸¹And R⁸²Independently of one another, have the above for R⁴¹And R⁴²One of the meanings given, preferably

R⁶¹Represents an unsubstituted alkyl group having 1 to 7C atoms, preferably a straight-chain alkyl group, more preferably an n-alkyl group, most preferably a propyl or pentyl group, an unsubstituted alkenyl group having 2 to 7C atoms, preferably a straight-chain alkenyl group, particularly preferably having 2 to 5C atoms, an unsubstituted alkoxy group having 1 to 6C atoms, or an unsubstituted alkenyloxy group having 2 to 6C atoms,

R⁶²represents an unsubstituted alkyl group having 1 to 7C atoms, an unsubstituted alkoxy group having 1 to 6C atoms or an unsubstituted alkenyloxy group having 2 to 6C atoms, and

l represents a number of 0 or 1,

R⁷¹denotes unsubstituted alkyl having 1 to 7 carbon atoms, preferably straight-chain alkyl, more preferably n-alkyl, most preferably propyl or pentyl, or unsubstituted alkenyl having 2 to 7C atoms, preferably straight-chain alkenyl, particularly preferably having 2 to 5C atoms,

R⁷²represents an unsubstituted alkyl group having from 1 to 7 carbon atoms, preferably having from 2 to 5 carbon atoms, an unsubstituted alkoxy group having from 1 to 6 carbon atoms, preferably having 1,2,3 or 4C atoms, or an unsubstituted alkenyloxy group having from 2 to 6C atoms, preferably having 2,3 or 4C atoms,

R⁸¹denotes unsubstituted alkyl having 1 to 7 carbon atoms, preferably straight-chain alkyl, more preferably n-alkylAlkyl, most preferably propyl or pentyl, or unsubstituted alkenyl having 2 to 7C atoms, preferably straight-chain alkenyl, particularly preferably having 2 to 5C atoms,

R⁸²represents an unsubstituted alkyl group having from 1 to 7 carbon atoms, preferably having from 2 to 5 carbon atoms, an unsubstituted alkoxy group having from 1 to 6 carbon atoms, preferably having 1,2,3 or 4C atoms, or an unsubstituted alkenyloxy group having from 2 to 6C atoms, preferably having 2,3 or 4C atoms, and

to represent

To represent

Preference is given to

More preferably

Z⁸Represents- (C ═ O) -O-, -CH₂-O-，-CF₂-O-or-CH₂-CH₂-, preferably- (C ═ O) -O-or-CH₂-O-, and

o represents a number of 0 or 1,

R⁹¹and R⁹²Independently of one another have the above for R⁷²The meaning given is that of the compounds,

R⁹¹preferably represents an alkyl group having 2 to 5 carbon atoms, preferably having 3 to 5 carbon atoms,

R⁹²preferably represents an alkyl group or an alkoxy group having 2 to 5 carbon atoms, more preferably an alkoxy group having 2 to 4 carbon atoms, or an alkenyloxy group having 2 to 4 carbon atoms.

To represent

p and q independently of one another denote 0 or 1, and

(p + q) preferably represents 0 or 1, and

to represent

In the case of (1), alternatively, it is preferable that p ═ q ═ 1,

e) optionally again, one or more compounds of the formula IN having a high dielectric constant perpendicular to the director and parallel to the director, preferably IN a concentration IN the range from 1% to 60%, more preferably IN the range from 5% to 40%, particularly preferably IN the range from 8% to 35%,

wherein

To represent

To represent

n represents a number of 0 or 1,

R¹¹and R¹²Independently of one another, represents alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably alkenyl having 1 to 7 carbon atoms, having 2 to 7 carbon atoms, alkenyloxy, alkoxyalkyl or fluorinated alkenyl, and preferably alkyl, alkoxy, alkenyl or alkenyloxy, most preferably alkyl, alkoxy or alkenyloxy, and R¹¹May alternatively represent R¹And R is¹²May alternatively represent X¹，

R¹Denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7C atoms, one of which is-CH₂The radical-may be replaced by cyclopropylene, 1, 3-cyclobutylene, 1, 3-cyclopentylene, 1, 3-cyclopentenylene, preferably cyclopropylene or 1, 3-cyclopentylene, alkenyl having from 2 to 7 carbon atoms, alkenyloxy, alkoxyalkyl or fluorinated alkenyl, in which one-CH-group₂The radical may be replaced by cyclopropylene, 1, 3-cyclobutylene, 1, 3-cyclopentylene, 1, 3-cyclopentenylene, preferably cyclopropylene or 1, 3-cyclopentylene, and preferably alkyl or alkenyl,

1, 3-cyclopentenylene is a moiety selected from the group of the formula:

preference is given to

More preferably

And

X¹denotes F, Cl, fluorinated alkyl, fluorinated alkenyl, fluorinated alkoxy or fluorinated alkenyloxy, the latter four radicals preferably having 1 to 4C atoms, preferably F, Cl, CF₃Or OCF₃In particular F is preferred for formulae I-1 and I-2 and OCF is preferred for formula I-4₃And

f) optionally again, one or more compounds of the formula B having a high dielectric constant perpendicular to the director and parallel to the director, preferably in a concentration in the range from 1% to 60%, more preferably in the range from 5% to 40%, particularly preferably in the range from 8% to 35%,

wherein

To represent

To represent

R^B1And R^B2Independently of one another, represents alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7C atoms, one of which is-CH₂The radical-may be replaced by cyclopropylene, 1, 3-cyclobutylene, 1, 3-cyclopentylene, 1, 3-cyclopentenylene, preferably cyclopropylene or 1, 3-cyclopentylene, alkenyl having from 2 to 7 carbon atoms, alkenyloxy, alkoxyalkyl or fluorinated alkenyl, in which one-CH-group₂The radical may be replaced by cyclopropylene, 1, 3-cyclobutylene, 1, 3-cyclopentylene, 1, 3-cyclopentenylene, preferably cyclopropylene or 1, 3-cyclopentylene, and is preferably alkyl, alkoxy, alkenyl or alkenyloxy, most preferably alkyl, alkoxy or alkenyloxy, and

n represents 0 or 1, preferably 0.

g) Optionally again, one or more compounds of the formula S having a high dielectric constant perpendicular to the director and parallel to the director, preferably in a concentration in the range from 1% to 60%, more preferably in the range from 5% to 40%, particularly preferably in the range from 8% to 35%,

wherein

To represent

To represent

R^S1And R^S2Independently of one another, represents alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7C atoms, one of which is-CH₂The radicals may beCyclopropylene, 1, 3-cyclobutylene, 1, 3-cyclopentylene, 1, 3-cyclopentenylene, preferably replaced by cyclopropylene or 1, 3-cyclopentylene, alkenyl having 2 to 7 carbon atoms, alkenyloxy, alkoxyalkyl or fluorinated alkenyl, one of which-CH₂The radical may be replaced by cyclopropylene, 1, 3-cyclobutylene, 1, 3-cyclopentylene, 1, 3-cyclopentenylene, preferably cyclopropylene or 1, 3-cyclopentylene, and is preferably alkyl, alkoxy, alkenyl or alkenyloxy, most preferably alkyl, alkoxy or alkenyloxy, and

n represents 0 or 1, preferably 1.

The liquid-crystalline medium according to the present application preferably has a nematic phase.

In the compounds of the formula I, the radical N (R)¹³)(R¹⁴) Amines may also be preferred.

Preferred are the following embodiments:

p is a number of 2 and,

is an organic radical having 4 binding sites, preferably an alkanetetrayl unit having 1 to 30C atoms, where the radicals R are present in addition to m radicals R in the molecule¹²Besides, but independently thereof, one other H atom may also be replaced by R¹²Instead of or in addition to one or more other H atoms, may also be substituted by R¹²Instead, preference is given to having a mono-or divalent alkanetetrayl unit on each of the two terminal C atoms, one of which is-CH₂A group or a plurality of-CH₂The radicals-may be replaced by-O-or- (C ═ O) -in such a way that the two O atoms are not bonded directly to one another, or substituted or unsubstituted aromatic or heteroaromatic hydrocarbon radicals having a valency of up to 8, where R is present in the molecule in addition to the m radicals present in the molecule¹²Furthermore, but independently thereof, one other H atom may be replaced by R¹²Instead of or in addition to one or more other H atoms, may be replaced by R¹²Instead of this, the user can,

to represent

(biphenyl-1, 1 ', 3, 3' -diyl),

(benzene-1, 2,4, 5-diyl),>CH-[CH₂]_r-CH<(where r ∈ {0,1,2,3,4,5 to 18}, -CH₂-(CH-)-[CH₂]_q-(CH-)-CH₂-<(where q ∈ {0,1,2,3,4,5 to 16},

to represent

(benzene-1, 3, 5-triyl),

(benzene-1, 2, 4-triyl) or>CH-[CH₂]_r-CH₂- (where r ∈ {0,1,2,3,4,5 to 18}) or

represents-CH₂-[CH₂]_r-CH₂- (where r. epsilon. {0,1,2,3,4,5 to 18}), octane-1, 8-diyl, heptane-1, 7-diyl, hexane-1, 6-diyl, pentane-1, 5-diyl, butane-1, 4-diyl, propane-1, 3-diyl, ethane-1, 2-diyl, or

(1, 4-phenylene group),

(1, 3-phenylene group),

(1, 2-phenylene) or

(1, 4-Cyclohexylidene)

In an alternative preferred embodiment of the process according to the invention,

p represents 1.

In the present application, all elements contain their corresponding isotopes. In particular, one or more H in the compound may be replaced by D, and this is also particularly preferred in some embodiments. The corresponding highly deuteration of the corresponding compound enables, for example, monitoring and identification of the compound. This can be very helpful in some cases, especially in the case of compounds of formula I.

In the context of the present application, it is,

alkyl particularly preferably denotes straight-chain alkyl, in particular CH₃-,C₂H₅-,n-C₃H₇-,n-C₄H₉-or n-C₅H₁₁-, and

alkenyl particularly preferably represents CH₂＝CH-，E-CH₃-CH＝CH-，CH₂＝CH-CH₂-CH₂-，E-CH₃-CH＝CH-CH₂-CH₂-，E-(n-C₃H₇)-CH＝CH-。

The liquid-crystalline media according to the application preferably comprise a total of from 1ppm to 2500ppm, preferably from 1ppm to 1500ppm, preferably from 1 to 600ppm, even more preferably from 1 to 250ppm, preferably to 200ppm, and very particularly preferably from 1ppm to 100ppm, of compounds of the formula I.

In a preferred embodiment of the present invention, in the compounds of formula I,

to represent

(biphenyl-1, 1 ', 3, 3' -diyl) or

(benzene-1, 2,4, 5-diyl)

To represent

(benzene-1, 3, 5-triyl) or

(benzene-1, 2, 4-triyl),

is represented by- (CH)₂-)₂，-(CH₂-)₃，-(CH₂-)₄，-(CH₂-)₅，-(CH₂-)₆，-(CH₂-)₇，-(CH₂-)₈I.e. ethane-1, 2-diyl, propane-1, 3-diyl, butane-1, 4-diyl, pentane-1, 5-diyl, hexane-1, 6-diyl, heptane-1, 7-diyl, octane-1, 8-diyl,

(1, 4-phenylene group),

(1, 3-phenylene group),

(1, 2-phenylene) or

(trans-1, 4-cyclohexylidene) and/or

-Z¹²-S¹¹-Z¹¹-represents, independently of one another at each occurrence, -O-, S¹¹-O-,-O-S¹¹-O-,-(C＝O)-O-S¹¹-O-，-O-(C＝O)-S¹¹-O-,-O-(C＝O)-S¹¹-(C＝O)-O-,-O-S¹¹-(C＝O)-O-,-(C＝O)-O-S¹¹-C,-(C＝O)-O-S¹¹-O- (C ═ O) -or- (N-R)¹³)-S¹¹-O-,-(N-R¹³-C(＝O)-S¹¹- (C ═ O) -O or a single bond, preferably-O-, -S¹¹-O-,-O-S¹¹-O-,-(C＝O)-O-S¹¹-O,-O-(C＝O)-S¹¹-O-or-O-S¹¹- (C ═ O) -O-, and/or

S¹¹Preference tableAn alkylene group having 1 to 20C atoms, and/or

R¹¹If present, represents alkyl, alkoxy or H, preferably H or alkyl, and/or

R¹²Represents H, methyl, ethyl, propyl, isopropyl or 3-heptyl, or cyclohexyl.

In a preferred embodiment of the present application, in the compounds of the formula I,

represents a group selected from the following formulae

represents a group selected from the following formulae

In a preferred embodiment of the application, in the compounds of formula I, wherein p preferably represents 1,

to represent

preferably-O-S¹¹-O-,-S¹¹-O-or-O-S¹¹-O-S is particularly preferred¹¹-O-or-S¹¹-O-。

In a further preferred embodiment of the application, in the compounds of the formula I,

preferably represents a group selected from the following formulae

In a further preferred embodiment of the application, where p is 2, which may be the same or different from those described above, in the compounds of the formula I,

preferably represents a group selected from the following formulae

In a further preferred embodiment of the application, which may be identical to or different from those described above, in the compounds of the formula I the radicals

Represent independently of each other at each occurrence

Preference is given to

In a particularly preferred embodiment of the present application, in the compounds of the formula I, all radicals present are

Have the same meaning.

These compounds are very suitable as stabilizers in liquid-crystal mixtures. In particular, they stabilized the VHR of the mixture against UV exposure.

In a preferred embodiment of the present invention, the media according to the invention comprise in each case one or more compounds of the formula I selected from the following group of compounds of the formulae I-1 to I-11: preferably from the group of compounds of the formulae I-1 to I-10, particularly preferably from the group of compounds of the formulae I-2 to I-10 and very particularly preferably from the group of compounds of the formulae I-2 and/or I-3 and/or I-4,

in an even more preferred embodiment of the present invention, the media according to the invention comprise in each case one or more compounds of the formula I selected from the compounds of the formulae I-1 and/or I-3 to I-7 and/or I-8 and/or I-9 and/or I-10 below.

In an even more preferred embodiment of the present invention, the media according to the invention comprise in each case one or more compounds of the formula I selected from the compounds of the formulae I-2 and/or I-7 and/or I-9 and/or I-10 below.

In addition to the compounds of the formula I or preferred subformulae thereof, the media according to the invention preferably comprise one or more compounds of the formula II in a total concentration of from 1% or more to 90% or less, preferably from 10% or more to 80% or less, particularly preferably from 20% or more to 70% or less.

In a preferred embodiment of the present invention, the liquid-crystalline medium comprises one or more compounds selected from the group consisting of formula II-1 and formula II-2, preferably dielectrically positive, preferably having a dielectric anisotropy of 3 or more:

wherein the parameters have the respective meanings indicated above under formula II, and L²³And L²⁴Independently of one another, H or F, preferably L²³Represents F, and

has the advantages of

One of the meanings given and, in the case of the formulae II-1 and II-2, X²Preferably represents F or OCF₃F is particularly preferred, and in the case of formula II-2,

independently of one another, preferably represent

In addition to the compounds of the formula I or preferred subformulae thereof, the media according to the invention preferably comprise one or more compounds of the formula III in a total concentration of from 1% or more to 40% or less, preferably from 3% or more to 20% or less, particularly preferably from 4% or more to 10% or less.

The compound of formula III is preferably selected from compounds of formulae III-1 and III-2:

wherein the parameters have the meanings given under formula III and the media according to the invention can comprise one or more compounds of the formula III-3 in place of or in addition to the compounds of the formula III-1 and/or III-2

Wherein the parameters have the respective meanings indicated above, and the parameter L³¹And L³²Independently of each other and independently of the other parameters, H or F.

The liquid-crystalline medium preferably comprises a compound selected from the group consisting of the formulae II-1 and II-2, where L²¹And L²²And/or L²³And L²⁴Both represent F.

In a preferred embodiment, the liquid-crystalline medium comprises a compound selected from the group consisting of the formulae II-1 and II-2, where L²¹,L²²,L²³And L²⁴Both represent F.

The liquid-crystalline medium preferably comprises one or more compounds of the formula II-1. The compound of formula II-1 is preferably selected from compounds of formulae II-1a to II-1e, preferably one or more compounds of formulae II-1a and/or II-1b and/or II-1d, preferably of formulae II-1a and/or II-1d or II-1b and/or II-1d, most preferably of formulae II-1 d:

wherein the parameters have the respective meanings indicated above, and L²⁵And L²⁶Independently of one another and of other parameters, H or F, and preferably, in the formulae II-1a and II-1b, L²¹And L²²Both represent F, in the formulae II-1c and II-1d, L²¹And L²²All represent F and/or L²³And L²⁴Both represent F, and in the formula II-1e, L²¹，L²²And L²³Represents F.

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

wherein the parameters have the respective meanings indicated above, and L²⁵To L²⁸Independently of one another, H or F, preferably L²⁷And L²⁸All represent H, particularly preferably L²⁶Represents H.

The liquid-crystalline medium preferably comprises a compound selected from the group consisting of the formulae II-1a to II-1e, where L²¹And L²²All represent F and/or L²³And L²⁴Both represent F.

In a preferred embodiment, the liquid-crystalline medium comprises a compound selected from the group consisting of the formulae II-2a to II-2k, where L²¹，L²²，L²³And L²⁴Both represent F.

Particularly preferred compounds of the formula II-2 are those of the formula II-2a-1 and/or II-2h-1 and/or II-2 k-2:

wherein R is²And X²Has the meaning indicated above, and X²Preferably represents F.

The liquid-crystalline medium preferably comprises one or more compounds of the formula III-1. The compound of formula III-1 is preferably selected from compounds of formulae III-1a to III-1j, preferably from formulae III-1c, III-1f, III-1g and III-1 j:

wherein the parameters have the meanings given above, and preferably wherein the parameters have the corresponding meanings indicated above, the parameter L³⁵And L³⁶H or F, independently of one another and of the other, and a parameter L³⁵And L³⁶Independently of each other and of the other parameters, H or F.

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

wherein R is³Have the meaning indicated above.

The liquid-crystalline medium preferably comprises one or more compounds of the formula III-1f, which are preferably selected from the group consisting of compounds of the formulae III-1f-1 to III-1f-6, preferably of the formulae III-1f-1 and/or III-1f-2 and/or III-1f-3 and/or III-1f-6, more preferably of the formulae III-1 f-6:

wherein R is³Have the meaning indicated above.

The liquid-crystalline medium preferably comprises one or more compounds of the formula III-1g, which are preferably selected from compounds of the formulae III-1g-1 to III-1g-5, preferably of the formula III-1 g-3:

wherein R is³Have the meaning indicated above.

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

wherein the parameters have the meanings given above, and X³Preferably represents F.

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

The liquid-crystalline medium preferably comprises one or more compounds of the formula III-1j, which are preferably selected from the group consisting of compounds of the formulae III-1j-1 and III-1j-2, preferably of the formula III-1 j-1:

wherein the parameters have the meanings given above.

The liquid-crystalline medium preferably comprises one or more compounds of the formula III-2. The compound of formula III-2 is preferably selected from compounds of formulae III-2a and III-2b, preferably formula III-2 b:

wherein the parameters have the respective meanings indicated above, and the parameter L³³And L³⁴Independently of each other and of the other parameters, H or F.

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

wherein R is³Have the meaning indicated above.

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

wherein R is³Have the meaning indicated above.

The media according to the invention may also comprise, instead of or in addition to the compounds of the formulae III-1 and/or III-2, one or more compounds of the formula III-3

Wherein the parameters have the respective meanings indicated above in formula III.

These compounds are preferably selected from the formulae III-3a and III-3 b:

wherein R is³Have the meaning indicated above.

The liquid-crystalline medium according to the invention preferably comprises one or more dielectrically neutral compounds whose dielectric anisotropy is preferably from-1.5 to 3, preferably selected from the compounds of the formulae VI, VII, VIII and IX.

In the present application, all elements include their respective isotopes. In particular, one or more H in the compound may be replaced by D, and this is also particularly preferred in some embodiments. The corresponding highly deuterated formation of the corresponding compound enables, for example, the detection and identification of the compound. This may be very helpful in certain cases, especially in the case of the compounds of the formula I.

In the context of the present application, it is,

alkenyl particularly preferably represents CH₂＝CH-,E-CH₃-CH＝CH-，CH₂＝CH-CH₂-CH₂-，E-CH₃-CH＝CH-CH₂-CH₂-or E- (n-C)₃H₇)-CH＝CH-。

In a preferred embodiment of the present invention, the medium according to the invention comprises one or more compounds of the formula B, preferably of the formula B-1, preferably in a concentration of from 1% to 20%, particularly preferably from 2% to 15% and very particularly preferably from 3% to 9%,

wherein the parameters have the respective meanings given above under formula B, and preferably

R^B1And R^B2In each case independently of one another represent unsubstituted alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 7C atoms or alkenyl or alkenyloxy having 2 to 7C atoms, preferably both represent alkoxy, and

L^B1and L^B2In each case independently of one another denote F or Cl, preferablyAnd F, selecting.

In a particularly preferred embodiment, the medium according to the invention comprises one or more compounds selected from the group consisting of the compounds of the formulae OH-1 to OH-6,

these compounds are very suitable for stabilizing media against thermal loads.

In a further preferred embodiment of the present invention, in which the media according to the invention comprise in particular one or more compounds of the formula I in which p represents 2 and n represents 2,3 or 4, preferably 2 or 3, particularly preferably 3, these media have excellent stability.

In a further preferred embodiment of the present invention, the media according to the invention comprise at least one or more compounds of the formula I in each case, in which p represents 1 and n represents 3,4,5 or 6, preferably 4, and the radical-Z¹¹-S¹¹-Z¹²-represents an omega-dioxyalkylene group, i.e. -O-S¹¹O-these media have excellent stability.

The invention also relates to an electro-optical display or an electro-optical component comprising a liquid-crystalline medium according to the invention. Preferably electro-optical displays based on the IPS, FFS, VA or ECB effect, preferably based on the IPS or FFS effect, and in particular those addressed by active matrix addressing means.

The invention therefore likewise relates to the use of the liquid-crystalline media according to the invention IN electro-optical displays or electro-optical components, and to a process for the preparation of the liquid-crystalline media according to the invention, which is characterized IN that one or more compounds of the formula I are mixed with one or more compounds of the formula II, preferably with one or more compounds of the sub-formula II-1, and with one or more further compounds, preferably selected from the compounds of the formulae III and IV and/or V and/or VI to IX and/or IN and/or B and/or S.

Furthermore, the present invention relates to a method for stabilizing a liquid-crystalline medium comprising one or more compounds of the formula II and one or more compounds selected from the group consisting of the compounds of the formulae III to IX, B, S and IN, characterized IN that one or more compounds of the formula I are added to the medium.

In a particularly preferred embodiment, the medium comprises one or more compounds of the formula IV selected from the group consisting of the compounds of the formulae IV-1 to IV-4, preferably of the formulae IV-1 and/or IV-2,

wherein

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

alkinyl and alkinyl', independently of one another, denote alkenyl having 2 to 5C atoms, preferably having 2 to 4C atoms, particularly preferably 2C atoms.

alkenyl' denotes alkenyl having 2 to 5C atoms, preferably having 2 to 4C atoms, particularly preferably having 2 to 3C atoms, and

alkoxy denotes alkoxy having 1 to 5C atoms, preferably having 2 to 4C atoms.

In a particularly preferred embodiment, the medium according to the invention comprises one or more compounds of the formula IV-1 and/or one or more compounds of the formula IV-2.

Particularly preferred compounds of formula IV-1 are compounds selected from the group consisting of

Wherein alkyl has the meaning given above, and preferably represents in each case independently of one another an alkyl group having 1 to 6, preferably having 2 to 5, C atoms, and particularly preferably an n-alkyl group.

Particularly preferred compounds of the formula IV are those selected from the group consisting of

In another preferred embodiment, the medium comprises one or more compounds of formula V, which are selected from the group consisting of compounds of formulae V-1 to V-11, preferably from the group consisting of compounds of formulae V-1 to V-5,

wherein the parameters have the meanings given above under formula V, and

Y⁵represents H or F, and preferably

R⁵¹Represents an alkyl group having 1 to 7C atoms or an alkenyl group having 2 to 7C atoms, and

R⁵²denotes alkyl having 1 to 7C atoms, alkenyl having 2 to 7C atoms or alkoxy having 1 to 6C atoms, preferably alkyl or alkenyl, particularly preferably alkenyl.

In another preferred embodiment, the medium comprises one or more compounds of formula V-1, which are selected from the group consisting of compounds of formulae V-1a and V-1b, preferably of formula V-1b,

wherein

alkoxy denotes alkoxy having 1 to 5C atoms, preferably having 2 to 4C atoms.

In another preferred embodiment, the medium comprises one or more compounds of formula V-3, which are selected from the group consisting of compounds of formulae V-3a and V-3b,

wherein

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

alkenyl denotes alkenyl having 2 to 7C atoms, preferably having 2 to 5C atoms.

In another preferred embodiment, the medium comprises one or more compounds of formula V-4, which are selected from the group consisting of compounds of formulae V-4a and V-4b,

wherein

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

In another preferred embodiment, the medium comprises one or more compounds of formula V-5, which are selected from compounds of formulae V-5a to V5d, preferably of formulae V-5a and/or V-5b,

wherein

alkinyl and alkinyl', independently of one another, denote alkenyl having 2 to 5C atoms, preferably having 2 to 4C atoms, particularly preferably 4C atoms.

The liquid-crystalline medium according to the invention may comprise one or more chiral compounds.

Particularly preferred embodiments of the present invention satisfy one or more of the following conditions, wherein acronyms (abbreviations) are explained in tables a to C and are illustrated by way of example in table D.

i. The birefringence of the liquid-crystalline medium is 0.060 or more, particularly preferably 0.070 or more.

The birefringence of the liquid-crystalline medium is 0.130 or less, particularly preferably 0.120 or less.

The birefringence of the liquid-crystalline medium is in the range of 0.090 or higher to 0.120 or lower.

The liquid-crystalline medium has a negative dielectric anisotropy having a value of 2.0 or more, particularly preferably 3.0 or more.

v. the liquid-crystalline medium has a negative dielectric anisotropy which has a value of 5.5 or less, particularly preferably 5.0 or less.

The liquid crystal medium has a negative dielectric anisotropy having a value in the range of 3.6 or more to 5.2 or less.

The total concentration of compounds of formula II in the entire mixture is 25% or more, preferably 30% or more, and preferably in the range of 25% or more to 49% or less, particularly preferably in the range of 29% or more to 47% or less, and very particularly preferably in the range of 37% or more to 44% or less.

The liquid-crystalline medium comprises one or more compounds of formula IV, which are selected from the compounds of the following formulae: CC-n-V and/or CC-n-Vm, particularly preferably CC-3-V, preferably in a concentration of at most 50% or less, particularly preferably at most 42% or less, and optionally additionally CC-3-V1, preferably in a concentration of at most 15% or less, and/or CC-4-V, preferably in a concentration of at most 20% or less, particularly preferably at most 10% or less.

The total concentration of compounds of formula CC-3-V throughout the mixture is 20% or higher, preferably 25% or higher.

The proportion of the compounds of the formulae II and III in the entire mixture is 10% or more, and preferably 75% or less.

Liquid-crystalline media consist essentially of, preferably consist of, compounds of the formulae I, II, III, IV, V and B and/or S.

The invention furthermore relates to an electro-optical display with active matrix addressing based on the VA or ECB effect, which is characterized in that it contains a liquid-crystalline medium according to the invention as a dielectric.

The liquid-crystal mixture preferably has a nematic phase range having a width of at least 80 degrees and at most 30mm at 20 DEG C²·s^-1Flow viscosity v of₂₀。

The liquid-crystal mixtures according to the invention have a Δ ∈ of from-0.5 to-8.0, in particular from-1.5 to-6.0, and very particularly preferably from-2.0 to-5.0, where Δ ∈ denotes the dielectric anisotropy.

Rotational viscosity gamma₁Preferably 150 mPas or less, in particular 120 mPas or less and very particularly preferably 120 mPas or less.

The mixtures according to the invention are suitable for all IPS and FFS-TFT applications. They are also suitable for all VA applications, for example, VAN, MVA, (S) -PVA and ASV applications, and PALC applications with negative Δ ∈.

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

The liquid-crystalline media according to the invention preferably comprise from 4 to 15, in particular from 5 to 12 and particularly preferably 10 or fewer compounds. These are preferably selected from compounds of formulae I, II and III-1 to III-4, and/or IV and/or V.

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

In addition to the compounds of the formulae I to V, further constituents may also be present, for example in an amount of up to 45%, but preferably up to 35%, in particular up to 10%, of the entire mixture.

The media according to the invention may optionally also comprise a dielectrically positive component, preferably in a total concentration of 10% or less, based on the entire medium.

In a preferred embodiment, the liquid-crystalline medium according to the invention comprises, based on the entire mixture, in total,

from 100ppm or more to 2500ppm or less, preferably from 300ppm or more to 2000ppm or less, particularly preferably from 500ppm or more to 1500ppm or less, and very particularly preferably from 700ppm or more to 1200ppm or less, of a compound of the formula I,

20% or more to 60% or less, preferably 25% or more to 50% or less, particularly preferably 30% or more to 45% or less of the compound of the formula II, and

50% or more to 70% or less of a compound of formulae I to IX and/or IN and/or B and/or S.

In a preferred embodiment, the liquid-crystalline medium according to the invention comprises one or more compounds selected from the group consisting of the compounds of the formulae II, III, IV, V, VI, VII, VIII and IX, preferably from the compounds of the formulae II and/or III and/or IV and/or V, which, independently of one another, comprise one or more rings selected from the group consisting of the substituted 1, 4-phenylenes

In a particularly preferred embodiment of the above preferred embodiments, the liquid-crystalline medium according to the invention comprises one or more compounds selected from the group consisting of

In a preferred embodiment, the liquid-crystalline medium according to the invention comprises one or more compounds selected from the group consisting of the compounds of the formulae II, III, IV, V, VI, VII, VIII and IX, preferably from the compounds of the formulae II and/or III and/or IV and/or V, which comprise one end group or, if present, two end groups, preferably one end group, which is selected from the group consisting of the following end groups

3-fluoropropyl, cyclopropyl, cyclopropylmethyl, 2-cyclopropylethyl, cyclobutyl, cyclobutylmethyl, cyclopentyl and cyclopentylmethyl,

preferably selected from the group consisting of 3-fluoropropyl, cyclopropyl, cyclopropylmethyl, 2-cyclopropylethyl, cyclobutylmethyl and cyclopentylmethyl.

In a preferred embodiment, the liquid-crystalline medium according to the invention comprises a compound selected from the group consisting of the compounds of the formulae I, II, III, IV, V, In, B and S, preferably from the compounds of the formulae I, II and/or III and/or B and/or S; they preferably consist predominantly, particularly preferably essentially and very particularly preferably virtually completely, of the compounds of the formula.

The liquid-crystalline media according to the invention preferably have a nematic phase which is in each case at least-20 ℃ or less to 70 ℃ or more, particularly preferably-30 ℃ or less to 80 ℃ or more, very particularly preferably-40 ℃ or less to 85 ℃ or more and most preferably-40 ℃ or less to 90 ℃ or more.

The expression "having a nematic phase" here means on the one hand that no smectic phases and no crystallization are observed at low temperatures at the corresponding temperatures and on the other hand that no clearing occurs on heating of the nematic phase. The studies at low temperature were carried out in a flow viscometer at the corresponding temperature and checked by storage in a test cell having a cell thickness corresponding to the electro-optical application for at least 100 hours. If the storage stability at a temperature of-20 ℃ in the corresponding test cartridge is 1000 hours or more, the medium is considered to be stable at that temperature. The corresponding times were 500 hours and 250 hours at-30 ℃ and-40 ℃ respectively. The clearing point is measured in the capillary by conventional methods at elevated temperature. In addition, the shelf life of bulk (inbulk) (1mL sample) at low temperature was determined in glass bottles at temperatures of-20 ℃ or-30 ℃. At these temperatures, preferably at-30 ℃, the stable shelf life is preferably 120 hours or more, particularly preferably 240 hours or more.

In a preferred embodiment, the liquid-crystalline medium according to the invention is characterized by an optical anisotropy in the moderate to low range. The birefringence value is preferably in the range of 0.065 or more to 0.130 or less, particularly preferably in the range of 0.080 or more to 0.120 or less, and very particularly preferably in the range of 0.085 or more to 0.110 or less.

In this embodiment, the liquid-crystalline medium according to the invention has a negative dielectric anisotropy and a relatively high absolute value of the dielectric anisotropy (| Δ ∈ |), which is preferably in the range from 2.7 or more to 5.3 or less, preferably to 4.5 or less, preferably from 2.9 or more to 4.5 or less, particularly preferably from 3.0 or more to 4.0 or less and very particularly preferably from 3.5 or more to 3.9 or less.

The liquid-crystalline medium according to the invention has a relatively low threshold voltage (V)₀) A value in the range of 1.7V or more to 2.5V or less, preferably 1.8V or more to 2.4V or less, particularly preferably 1.9V or more to 2.3V or less and very particularly preferably 1.95V or more to 2.1V or less.

In a further preferred embodiment, the liquid-crystalline media according to the invention preferably have a relatively low mean dielectric anisotropy value (. epsilon.)_av.≡(ε_||+2ε_⊥) /3), which is preferably in the range from 5.0 or more to 7.0 or less, preferably from 5.5 or more to 6.5 or less, still more preferably from 5.7 or more to 6.4 or less, particularly preferably from 5.8 or more to 6.2 or less and very particularly preferably from 5.9 or more to 6.1 or less.

Furthermore, the liquid-crystalline media according to the invention have a high VHR value in the liquid-crystal cell.

In the case, these are preferably greater than or equal to 95%, preferably greater than or equal to 97%, particularly preferably greater than or equal to 98% and very particularly preferably greater than or equal to 99% in the case freshly filled at 20 ℃ and these are greater than or equal to 90%, preferably greater than or equal to 93%, particularly preferably greater than or equal to 96% and very particularly preferably greater than or equal to 98% after 5 minutes in the oven at 100 ℃ in the case.

Generally, here liquid-crystalline media with a low addressing voltage or threshold voltage have a lower VHR than those with a higher addressing voltage or threshold voltage, and vice versa.

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

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

Unless otherwise indicated, the individual compounds are generally used in the mixture in concentrations of from 1% or more to 30% or less, preferably from 2% or more to 30% or less and particularly preferably from 3% or more to 16% or less.

In a preferred embodiment, the liquid-crystalline medium according to the invention comprises

One or more compounds of formula I and

one or more compounds of the formula IV, preferably selected from the group consisting of the compounds of the formulae CC-n-V and CC-n-Vm, preferably CC-3-V, CC-3-V1, CC-4-V and CC-5-V, particularly preferably from the compounds CC-3-V, CC-3-V1 and CC-4-V, very particularly preferably the compound CC-3-V, and optionally additionally one or more compounds CC-4-V and/or CC-3-V1.

In a preferred embodiment, the liquid-crystalline medium according to the invention comprises:

one or more compounds of formula I and/or

One or more compounds of formula II, preferably of formula PUQU-n-F, CDUQU-n-F, APUQU-n-F, DPUQU-n-F and PGUQU-n-F and/or

One or more compounds of formula III, preferably of formula CCG-n-FCCP-n-OT, CLP-n-T, CGG-n-F, CGG-n-OD and PPGU-n-F and/or

One or more compounds of formula IV, preferably of formula CC-n-V, CC-n-Vm, CC-n-m, CC-V-V, CCVC-n-V and/or

One or more compounds of formula V, preferably of formula CP-n-Om, CCP-n-m, CCP-V-n, CCP-V2-n, CLP-V-n, CCVC-n-V, CGP-n-m, PGP-n-m, PGP-n-mV and CPGP-n-m and/or

Optionally, preferably essentially, one or more compounds of the formula VI, preferably of the formula Y-n-Om, Y-nO-Om and/or CY-n-Om, selected from the group consisting of the formulae Y-3-O1, Y-4O-O4, CY-3-O2, CY-3-O4, CY-5-O2 and CY-5-O4 and/or

Optionally, preferably essentially, one or more compounds of formula VII-1, preferably selected from the group consisting of compounds of formula CCY-n-m and CCY-n-Om, preferably of formula CCY-n-Om, preferably selected from the group consisting of compounds of formula CCY-3-O2, CCY-2-O2, CCY-3-O1, CCY-3-O3, CCY-4-O2, CCY-3-O2 and CCY-5-O2, and/or

Optionally, preferably essentially, one or more compounds of formula VII-2, preferably of formula CLY-n-Om, preferably selected from the group consisting of formula CLY-2-O4, CLY-3-O2, CLY-3-O3 and/or

One or more compounds of formula VIII, preferably of formula CZY-n-On and CCOY-n-m and/or

One or more compounds of formula IX, preferably selected from compounds of formula PYP-n-m and PGIY.n-Om and/or

One or more compounds of formula B and/or

One or more compounds of formula S and/or

Optionally, preferably essentially, one or more compounds of the formula IV, preferably selected from the group consisting of the compounds of the formulae CC-n-V, CC-n-Vm and CC-nV-Vm, preferably CC-3-V, CC-3-V1, CC-4-V, CC-5-V and CC-V-V, particularly preferably from the compounds CC-3-V, CC-3-V1, CC-4-V and CC-V-V, very particularly preferably the compound CC-3-V, and optionally additionally one or more compounds CC-4-V and/or CC-3-V1 and/or CC-V-V.

In a particularly preferred embodiment of the invention, the medium according to the invention comprises one or more compounds of the formula PPGU-n-F. The compounds of the formula PPGU-n-F are also very suitable as stabilizers in liquid-crystal mixtures.

In a particularly preferred embodiment of the present invention, the medium according to the invention comprises one or more compounds of the formula IX.

The compounds of the formula IX are also very suitable as stabilizers in liquid-crystal mixtures, in particular when p ═ q ═ 1 and ring A⁹In the case of 1, 4-phenylene. In particular, they stabilized the VHR of the mixture for UV exposure.

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

wherein the parameters have the meanings given under formula IX and F/H denotes F or H.

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

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

For the purposes of the present invention, in each case, the following definitions relate to the description of the constituents of the composition, unless otherwise stated:

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

- "consists essentially of …": the concentration of the component in question in the composition is preferably 50% or more, particularly preferably 55% or more and very particularly preferably 60% or more,

- "consists essentially of …": the concentration of the component in question in the composition is preferably 80% or more, particularly preferably 90% or more and very particularly preferably 95% or more, and

- "consists practically completely of …": the concentration of the component in question in the composition is preferably 98% or more, particularly preferably 99% or more and very particularly preferably 100.0%.

This applies to the medium as a composition with its ingredients (which may be both components and compounds), and also to the components with their ingredients (compounds). The term "comprising" only when referring to the concentration of the individual compounds relative to the entire medium means that the concentration of the compound in question is preferably 1% or more, particularly preferably 2% or more, very particularly preferably 4% or more.

For the purposes of this invention, "≦" means less than or equal to, preferably less than, and "≧" means greater than or equal to, preferably greater than.

With respect to the present invention, it is,

represents a trans-1, 4-cyclohexylene group,

represents 1, 4-cyclohexylene, preferably trans-1, 4-cyclohexylene, and

represents a1, 4-phenylene group.

For the purposes of the present invention, the expression "dielectrically positive compounds" means compounds having a. DELTA.. epsilon.of >1.5, the expression "dielectrically neutral compounds" generally means those in which-1.5. ltoreq. DELTA.. epsilon.ltoreq.1.5 and the expression "dielectrically negative compounds" means those in which. DELTA.. epsilon. -1.5. The dielectric anisotropy of the compounds here was determined in each case by dissolving 10% of the compound in a liquid-crystalline host and measuring the capacitance of the resulting mixture at 20 ℃ at a frequency of 1kHz in at least one test cell with homeotropic alignment and with a cell thickness of 20 μm with homeotropic alignment. The measurement voltage is usually 1.0V, but always below the capacitance threshold of the respective liquid-crystal mixture under study.

The host mixture for dielectrically positive and dielectrically neutral compounds was ZLI-4792 and the host mixture for dielectrically negative compounds was ZLI-2857, both from Merck KGaA, Germany. The values of the respective compounds to be investigated are obtained from the change in the dielectric constant of the host mixture after addition of the compound to be investigated and extrapolation to 100% of the compound employed. The compound to be investigated is dissolved in the host mixture in an amount of 10%. If the solubility of the substance is too low for this purpose, the concentration is reduced by half step by step until the study can be carried out at the desired temperature.

The compounds of the formula I according to the invention or the compounds of the formula I used according to the invention can advantageously be prepared according to the following reaction schemes.

Synthesis scheme 1

Wherein n preferably represents 2,3 or 4, particularly preferably 3 or 4.

Synthesis scheme 2

Wherein n preferably represents 2,3 or 4, particularly preferably 3 or 4.

Synthesis scheme 3

Wherein m represents an integer of 3 to 6, particularly preferably 4 or 6.

In the above reaction schemes, Pg represents a protecting group and Rg represents a leaving group, and the parameter n has the meaning given in the case of formula I, furthermore, R¹With respect to R in the case of formula I¹¹The ring structures have the meanings given for ZG in the case of formula I, Sp¹And Sp²Respectively having the pair S in the case of formula I¹And S²The meanings given, and preferably n represents 3 or 4, the ring structure represents an aromatic or aliphatic group, Sp¹And Sp²Represents a single bond or an alkylene group having 1 to 8C atoms, and R¹Represents an alkyl group having 1 to 8C atoms.

With respect to the present invention, it is,

represents trans-1, 4-cyclohexylene, and

represents a1, 4-phenylene group.

For the purposes of the present invention, the expression "dielectrically positive compounds" means compounds having a. DELTA.. epsilon.of >1.5, the expression "dielectrically neutral compounds" means those in which-1.5. ltoreq. DELTA.. epsilon.ltoreq.1.5 and the expression "dielectrically negative compounds" means those in which. DELTA.. epsilon. -1.5. The dielectric anisotropy of the compounds here was determined in each case by dissolving 10% of the compound in a liquid-crystalline host and measuring the capacitance of the resulting mixture at 1kHz in at least one test cell with homeotropic alignment and with a cell thickness of 20 μm with homeotropic alignment. The measurement voltage is usually 0.5V to 1.0V, but always below the capacitance threshold of the respective liquid-crystal mixture under investigation.

The liquid-crystalline media according to the invention may also comprise further additives, such as stabilizers and/or pleochroic dyes and/or chiral dopants, if necessary in the usual amounts. The amount of these additives used is preferably from 0% or more to 10% or less in total, particularly preferably from 0.1% or more to 6% or less, based on the amount of the entire mixture. The concentration of the individual compounds employed is preferably from 0.1% or more to 3% or less. The concentration of these and similar additives is generally not considered when specifying the concentration and concentration range of the liquid-crystalline compound in the liquid-crystalline medium.

In a preferred embodiment, the liquid-crystalline medium according to the invention comprises a polymer precursor comprising one or more reactive compounds, preferably reactive mesogens, and, if necessary, further additives, such as a polymerization initiator and/or a polymerization moderator, in the usual amounts. The amount of these additives employed is in total 0% or more to 10% or less, preferably 0.1% or more to 2% or less, based on the amount of the whole mixture. The concentrations of these and similar additives are not taken into account when specifying the concentration and concentration range of the liquid-crystalline compound in the liquid-crystalline medium.

The compositions consist of a plurality of compounds, preferably 3 or more to 30 or less, particularly preferably 6 or more to 20 or less and very particularly preferably 10 or more to 16 or less compounds, which are mixed in a conventional manner. Generally, the desired amount of the component used in lesser amounts is dissolved in the component making up the major component of the mixture. This is advantageously carried out at elevated temperatures. Completion of the dissolution operation is particularly easily observed if the temperature chosen is above the clearing point of the main component. However, it is also possible to prepare the liquid-crystal mixtures in other conventional ways, for example using premixing or from so-called "multi-bottle systems".

The mixtures according to the invention exhibit a very broad nematic phase range of clearing points at 65 ℃ or more, a very favorable capacitance threshold, relatively high retention values and at the same time very good low-temperature stability at-30 ℃ and-40 ℃. Furthermore, the mixtures according to the invention are characterized by a low rotational viscosity γ 1.

It is obvious to the person skilled in the art that the media according to the invention for VA, IPS, FFS or PALC displays may also comprise compounds in which, for example, H, N, O, Cl, F have been replaced by the corresponding isotopes.

The structure of the liquid crystal display according to the invention corresponds to a general geometry, as described for example in EP-a 0240379.

The liquid-crystalline phases according to the invention can be modified by suitable additives in such a way that they can be used in any type of LCD displays disclosed hitherto, such as ECB, VAN, IPS, GH or ASM-VA.

Table E below shows possible dopants that can be added to the mixtures according to the invention. If the mixture contains one or more dopants, it (they) are used in amounts of from 0.01% to 4%, preferably from 0.1% to 1.0%.

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

For the purposes of the present invention, all concentrations are indicated in weight percent unless explicitly stated otherwise, and reference is made to the corresponding mixtures or mixture components unless explicitly stated otherwise.

Unless explicitly stated otherwise, all temperature values indicated in the present application, such as melting point T (C, N), transition T (S, N) from smectic (S) to nematic (N) phase and clearing point T (N, I), are expressed in degrees celsius (° C), and all temperature differences are correspondingly expressed in degrees difference (° or degrees).

For the purposes of the present invention, the term "threshold voltage" refers to the capacitive threshold (V), unless explicitly stated otherwise₀) Also known as Freedericks threshold.

In each case, unless explicitly stated otherwise, all Physical Properties are and have been determined in accordance with "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status 1997, 11 months, Merck KGaA, Germany and with a temperature of 20 ℃ applicable, and Δ n at 589nm and Δ ε at 1 kHz.

As switching behaviour, electro-optical properties, e.g. threshold voltage (V)₀) (capacitive measurement) was measured in a test cartridge prepared by Merck Japan. The measurement cell has a soda lime glass substrate and is constructed in an ECB or VA configuration (SE-1211 (mixing ratio 1:1) using diluent x 26, both from Nissan Chemicals, japan) with polyimide alignment layers that have rubbed perpendicular to each other and affected the homeotropic alignment of the liquid crystals. The surface area of the transparent, almost square ITO electrode was 1cm²。

Unless otherwise stated, no chiral dopant is added to the liquid-crystal mixture used, but the latter is also particularly suitable for applications in which this type of doping is necessary.

VHR was determined in a test cassette produced by Merck Japan. The measuring cell has a soda-lime glass substrate and is made of a polyimide with a layer thickness of 50nm which has been rubbed perpendicularly against one anotherA alignment layer (e.g. AL-3046 from Japan Synthetic Rubber, Japan, unless otherwise noted) or an alignment layer that has been rubbed perpendicular to each other as described in the examples. The layer thickness was uniform 6.0 μm. The surface area of the transparent ITO electrode was 1cm²。

VHR at 20 ℃ (VHR)₂₀) And at 100 ℃ (VHR)₁₀₀) After 5 minutes in an oven as determined in an instrument commercially available from Autronic Melchers, Germany. The voltage used has a frequency of 60Hz, or the conditions shown in the examples.

The accuracy of the VHR measurements depends on the corresponding values of VHR. The accuracy decreases with decreasing value. The deviations usually observed in the case of values in various order of magnitude ranges are compiled in the table below in terms of their order of magnitude.

The stability to UV radiation was investigated in a commercial instrument "Suntest CPS" from Heraeus, Germany. The sealed test box was irradiated for 2.0 hours without additional heating. The irradiation power in the wavelength range of 300nm to 800nm was 765W/m²V, or the conditions indicated in the examples. To simulate the so-called window glass mode, a UV "cut" filter with an edge wavelength of 310nm was used. In each series of experiments, at least four test cartridges were studied for each condition and the corresponding results were expressed as the average of the corresponding individual measurements. The reduction in voltage holding ratio (Δ VHR), which is typically caused by exposure to light, for example by UV irradiation of an LCD backlight, can be determined according to the following equation (1):

ΔVHR(t)＝VHR(t)-VHR(t＝0) (1).

the relative stability (S) of the LC mixture to the load at time t is determined according to equation (2) below_rel)：

Where "ref" represents the corresponding unstable mixture.

Another characteristic quantity which can characterize the conductivity of a liquid-crystal mixture in addition to VHR is the ion density. High values of ion density often result in display failures such as image sticking and flicker. The ion density is preferably determined in a test cartridge produced by Merck Japan ltd. The test cartridge has a substrate made of soda lime glass and is designed as a polyimide alignment layer with a polyimide layer thickness of 40nm (e.g. AL-3046 from Japan Synthetic Rubber, Japan, unless otherwise specified). The thickness of the liquid-crystal mixture layer was 6.0. mu.m. The area of the round transparent ITO electrode equipped with a protective ring is 1cm². The accuracy of the measurement method is about ± 15%. The cells were dried overnight in an oven at 120 ℃ and then filled with the relevant liquid crystal mixture.

Ion density was measured using an instrument commercially available from TOYO, Japan. The Measurement method is essentially a cyclic voltammetry-like Measurement method, as described in M.Inoue, "Recent Measurement of Liquid Crystal Material Characteristics", Proceedings IDW 2006, LCT-7-1, 647. In this method, the applied direct voltage is varied between a positive and a negative maximum value according to a pre-specified triangular curve. Thus, a complete run through the curve forms one measurement cycle. If the applied voltage is large enough to enable ions in the field to move to the corresponding electrode, an ion current is formed due to the discharge of the ions. The amount of charge transferred here is generally in the range of a few pC to a few nC. This necessitates a highly sensitive detection ensured by the above-mentioned instruments. The results are shown as current/voltage curves. The ion current here is evident by the appearance of a peak at a voltage which is less than the threshold voltage of the liquid-crystal mixture. Integration of the peak areas gives the value of the ion density of the mixture studied. Four cartridges were measured for each mixture. The triangular voltage has a repetition frequency of 0.033Hz, a measurement temperature of 60 ℃ and a maximum voltage of + -3V to + -10V, depending on the order of magnitude of the dielectric anisotropy of the relevant mixture.

Rotational viscosity was measured using a rotating permanent magnet method and flow viscosity was measured in a modified ubbelohde viscometer. For liquid crystal mixturesZLI-2293, ZLI-4792 and MLC-6608 (all from Merck KGaA, Darmstadt, Germany), rotational viscosity values of 161 mPas, 133 mPas and 186 mPas, respectively, measured at 20 ℃ and flow viscosity values (v) of 21mm, respectively²·s^-1、14mm²·s^-1And 27mm²·s^-1。

Unless explicitly stated otherwise, the following notations are used:

V₀represents the capacitance [ V ] at 20 DEG C]A threshold voltage;

n_erepresents the extraordinary refractive index measured at 20 ℃ and 589nm,

n_orepresents the ordinary refractive index measured at 20 ℃ and 589nm,

Δ n represents the optical anisotropy measured at 20 ℃ and 589nm,

ε_⊥representing the dielectric polarizability perpendicular to the director at 20 c and 1kHz,

ε_||representing the dielectric polarizability parallel to the director at 20 c and 1kHz,

deltaε represents the dielectric anisotropy at 20 ℃ and 1kHz,

cl.p. or

T (N, I) represents clearing point [ ° C ],

v represents the flow viscosity [ mm ] measured at 20 ℃²·s^-1],

γ 1 represents a rotational viscosity [ mPas ] measured at 20 ℃,

K₁the elastic constant [ pN ] representing the deformation "stretched" at 20 ℃],

K₂The elastic constant [ pN ] representing the "distortion" at 20 ℃ of the strain],

K₃The elastic constant [ pN ] representing the "bending" deformation at 20 ℃]And are and

LTS denotes the low temperature stability of the phase measured in the test cell,

VHR represents the voltage holding ratio of the voltage holding ratio,

Δ VHR represents a decrease in the voltage holding ratio, an

S_relIndicating the relative stability of VHR.

The following examples illustrate the invention without limiting it. However, they show the person skilled in the art the concept of using preferred mixtures of the compounds to be employed preferably and their respective concentrations and also their combinations with one another. Furthermore, the examples illustrate the properties and combinations of properties that can be obtained.

For the purposes of the present invention and in the examples which follow, the structures of the liquid-crystalline compounds are indicated by means of acronyms and are converted into chemical formulae in accordance with the following tables A to C. All radicals C_nH_2n+1，C_mH_2m+1And C_lH_2l+1Or C_nH_2n，C_mH2_mAnd C_lH_2lAre straight-chain alkyl or alkylene radicals, in each case having n, m and l C atoms. Table a shows the code for the ring elements of the compound core, table B lists the bridging units, and table C lists the symbolic meanings of the left and right hand end groups of the molecule. The acronym consists of a code for a ring element with an optional linking group, followed by a first hyphen and left-hand end group code, and a second hyphen and right-hand end group code. Table D shows exemplary structures of the compounds and their respective abbreviations.

Table a: ring element

Table B: bridging unit

TABLE C end groups

Where n and m are each integers and the three points are placeholders for other abbreviations from the table.

In addition to the compounds of the formula I, the mixtures according to the invention preferably also comprise one or more of the compounds mentioned below.

The following abbreviations are used:

(n, m and z are each, independently of one another, an integer, preferably from 1 to 6)

Table D

Table E shows the chiral dopants preferably used in the mixtures according to the invention.

TABLE E

In a preferred embodiment of the present invention, the medium according to the present invention comprises one or more compounds selected from the compounds of table E.

Table F shows that, in addition to the compounds of the formula I, stabilizers which can preferably also be used in the mixtures according to the invention are indicated. Where the parameter n represents an integer ranging from 1 to 12. In particular, the phenolic derivatives shown can be used as additional stabilizers, since they act as antioxidants.

TABLE F

In a preferred embodiment of the present invention, the medium according to the invention comprises one or more compounds selected from the compounds of table F, in particular one or more compounds selected from the following two formulae.

Examples

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

Examples of materials

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

1

2

3

4

5

6

7

And

8

9

and

10

11

the following examples illustrate the invention without limiting it in any way. However, the physical properties will make it clear to the skilled person what properties are to be achieved and within what ranges they may be varied. In particular, the combination of the various properties which can be preferably achieved is thus well defined for the person skilled in the art.

Synthesis example 1:bis (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) 2- {3- [2, 5-bis ({ 4-butyl-5- [ (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) oxy ] methyl ] oxy]-4- { [ (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) oxy]Carbonyl } -5-oxopentyl }) phenyl]Propyl } -2-butyl malonate1 Synthesis of

(substance example 1)

Step 1.1: synthesis of 3- [3, 4-bis (3-hydroxypropyl) phenyl ] propan-1-ol A

51.34g (484.0mmol) of anhydrous sodium carbonate were dissolved in 171.7ml of water. A solution of 25.0g (79.0mmol) of 1,2, 4-tribromobenzene and 67.7g (476mmol) of 2-butoxy-1, 2-oxacyclopentane-ane in 965.2ml of Tetrahydrofuran (THF) was added, 1.65ml (11.9mmol) of triethylamine were added and the mixture was stirred and degassed with a stream of argon for 30 min. 1.40g (7.49mmol) of palladium (II) chloride (59% palladium, anhydrous) and 1.85g (3.97mmol) of 2-dicyclohexylphosphino-2 ', 6 ' -diisopropoxy-1, 1 ' -biphenyl were added and the reaction mixture was stirred under reflux for 18 hours. The reaction mixture was cooled to Room Temperature (RT), water and methyl tert-butyl ether (MTBE) were added and the phases separated. The aqueous phase was extracted with MTBE and the combined organic phases were washed with saturated NaCl solution, dried over sodium sulfate, filtered and evaporated in vacuo. The product was obtained as a light yellow oil and filtered through silica gel with a mixture of Ethyl Acetate (EA) and methanol (9: 1). The product fractions were combined and evaporated in vacuo to give the reaction product as a pale yellow oil. The product was characterized by NMR spectroscopy.

¹H NMR(500MHz,DMSO-d6)

δ＝1.66(m_c,6H,CH₂),2.42–2.69(m_{(superposition with DMSO)},6H,CH₂,),3.36–3.49(m,6H,CH₂),4.44(t,J＝5.15Hz,1H),4.48(m_c,2H),6.92(dd,J＝1.7,7.72Hz,1H),6.95(d,J＝1.53Hz,1H),7.03(d,J＝7.7Hz,1H)。

Step 1.2: synthesis of 1,2, 4-tri (3-iodopropyl) benzene B

30.2ml (138mmol) of triphenylphosphine were dissolved in 513ml of acetonitrile and a solution of 34.92g (138.0mmol) of iodine in 513ml of acetonitrile was added dropwise with gentle cooling. An orange suspension formed during this addition. When the addition was complete, the mixture was stirred for a further 10 min. 13.3g (197mmol) of imidazole are added and subsequently a solution of 10.0g (39.3mmol) of triol A in 100ml of acetonitrile is added dropwise (a clear yellow solution forms during this addition). The reaction solution was stirred at RT for 3 hours (h) and carefully poured into cold sodium thiosulfate solution (discoloration occurred) and heptane was added. After washing by stirring, the phases were separated, the aqueous phase was extracted with heptane and the combined organic phases were washed with water, dried over sodium sulfate, filtered and evaporated in vacuo. The crude product was filtered through silica gel with heptane (H) and ethyl acetate (8:2) and the product fractions were evaporated to give the product as a colorless oil. The product was characterized by mass spectrometry.

MS(EI)＝582.0

Step 1.3: synthesis of 2-butylmalonyl dichloride C

76.00g (474.5mmol) of 2-butylmalonic acid are initially introduced into the reaction apparatus and warmed to 40 ℃. Then 90.00ml (1.240mol) of thionyl chloride (cautiously, releasing the gas) was added dropwise over the course of about 30 minutes and the mixture was stirred at Room Temperature (RT) for a further 5 hours (h). During this time period, the release of gas is significantly reduced. The reaction solution was then stirred at 50 ℃ for 18 hours and subsequently at 70 ℃ for 5 hours. At each temperature rise, a slight gas evolution occurs again. The reaction mixture was then cooled to room temperature and dissolved in 300ml of anhydrous toluene and the excess thionyl chloride was separated off together with toluene by distillation (8mBar, RT to maximum bath temperature 80 ℃) to give the crude product as a brownish liquid which was used directly in the next synthesis step.

Step 1.4: synthesis of bis (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) 2-butylmalonate D

45.3g (262.9mmol) 4-hydroxy-2, 2,6, 6-tetramethylpiperidine 1-oxyl (radical) and 40.1ml (289.15mmol) triethylamine are dissolved in 419ml Dichloromethane (DCM) and cooled to-11 ℃. A solution of 25.9g (131.4mmol) of acid chloride C in 252ml DCM was then added dropwise over the course of 1.5 hours (h) at-11 deg.C to-6 deg.C. The reaction mixture was stirred at maximum 0 ℃ for about 3h, thawed slowly and stirred at Room Temperature (RT) for 18 h. Adding saturated NaHCO at 3-6 deg.C under cooling₃The solution, the mixture was stirred briefly and the phases separated. The aqueous phase was extracted with DCM and the organic phases were combined, washed with saturated NaCl solution, dried over sodium sulfate, filtered and evaporated in vacuo. The resulting crude product (orange solid) was filtered through silica gel with DCM/MTBE (9:1) and the product fractions were evaporated in vacuo to give the product as orange crystals.

Step 1.5: synthesis of bis (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) 2- {3- [2, 5-bis ({ 4-butyl-5- [ (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) oxy ] -4- { [ (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) oxy ] carbonyl } -5-oxopentyl }) phenyl ] propyl } -2-butylmalonate 1

0.31g (7.80mmol) of sodium hydride (60% suspension in paraffin oil) was suspended in 9.7ml of N, N-Dimethylformamide (DMF). A solution of 3.75g (7.87mmol) of diradical D in 29.0ml DMF (releasing gas) is added dropwise with gentle cooling and the mixture is stirred at RT for 1 hour. To the reaction solution, 1.40g (2.39mmol) of triiodide B was added dropwise (5 minutes exotherm 5 ℃ C.), and the mixture was stirred at room temperature for 3 hours. The reaction mixture was carefully added to the ammonium chloride solution and extracted with MTBE. The phases were separated, the aqueous phase was extracted with MTBE, washed with saturated NaCl solution, dried over sodium sulfate, filtered and evaporated in vacuo. The resulting orange crude product was filtered through silica gel with ethyl acetate/heptane (1:1) and the product fractions were evaporated in vacuo to give the product as an orange solid, which bubbled in a glassy manner. The product had the following properties.

Phase (1): glass transition Temperature (TG) 23.5 deg.C, decomposition starting from 150 deg.C

MS(APCI)＝1605.1[M+H⁺]。

Synthesis example 2:bis (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) 2- (3- {3, 5-bis [ ({ 4-butyl-5- [ (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) oxy ] oxy]-4- { [ (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) oxy]Carbonyl } -5-oxopentyl } oxy) carbonyl]Synthesis of benzoyloxy } propyl) -2-butylmalonate 2

(substance example 2)

Step 2.1: bis (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) 2-butyl-2- [3-, (

Alk-2-yloxy) propyl]Synthesis of malonate E

3.20g (80.4mmol) of sodium hydride (60% suspension in paraffin oil) are suspended in 30ml of DMF. A solution of 32.40g (69.14mmol) of diradical D (from the synthesis of compound 1) in 300ml of DMF was added dropwise to the reaction solution (evolution of gas) under gentle cooling and the mixture was stirred at room temperature for 1 hour. A solution of 19.0g (85.16mmol) of 2- (3-bromopropoxy) tetrahydropyran in 200ml of DMF (exotherm 0.5 ℃ C.) is then added dropwise at RT. To degas the reaction mixture before the temperature was increased, a gentle stream of argon was passed through the reaction mixture for 30 minutes by means of a submerged pasteur pipette and the mixture was subsequently stirred at 35 ℃ for 18 hours. The reaction solution was cooled to RT, added to saturated NaCl solution, extracted with MTBE and the phases separated. The aqueous phase was extracted with MTBE and the organic phases were combined, washed with saturated NaCl solution, dried over sodium sulfate, filtered and evaporated in vacuo to give the crude product as a red oil which was filtered through silica gel with DCM/MTBE (9:1) for purification to give the product as a red oil.

Step 2.2: synthesis of bis (1-hydroxy-2, 2,6, 6-tetramethylpiperidin-4-yl) 2-butyl-2- (3-hydroxypropyl) malonate F

36.5g (56.1mmol) of the diradical E and 9.50g (55.2mmol) of toluene-4-sulfonic acid monohydrate are dissolved in a mixture of 500ml of methanol and 50ml of water and the mixture is stirred at 40 ℃ for 5 hours. The reaction solution was cooled to RT and NaHCO was used with cooling₃The solution was adjusted to pH 9 and evaporated in vacuo. The aqueous residue was extracted with MTBE and the combined organic phases were washed with saturated NaCl solution, dried over sodium sulphate, filtered and evaporated in vacuo to give a red oil which was dissolved in 250ml DCM and 6.00g (55.6mmol) MnO was added₂And the mixture was stirred at RT for 1 hour. (in the case of removal of the THP protecting group, the free radical is in some cases also converted into an OH compound, MnO being used₂Reversing it). The reaction mixture was filtered through silica gel with DCM and evaporated in vacuo. The crude product obtained was filtered through silica gel with DCM/MTBE (7:3) and the product fractions were evaporated in vacuo to give a red oil.

Step 2.3: synthesis of bis (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) 2- (3- {3, 5-bis [ ({ 4-butyl-5- [ (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) oxy ] -4- { [ (1-oxy-2, 2,6, 6-tetramethylpiperidin-4-yl) oxy ] carbonyl } -5-oxopentyl } oxy) carbonyl ] -benzoyloxy } propyl) -2-butylmalonate 2

6.70g (11.7mmol F and 50.0mg (0.41mmol)4- (dimethylamino) pyridine are dissolved in 100ml dichloromethane at RT and the mixture is cooled to 4 ℃ then 5.00ml (36.1mmol) triethylamine is added and then a solution of 1.00g (3.77mmol)1,3, 5-benzenetricarbonyl chloride in 10ml DCM is added dropwise at 3-4 ℃ when the exotherm is complete the mixture is warmed to RT and then stirred at RT for 18h then ammonium chloride solution is added under cooling, the mixture is stirred briefly, the phases are separated and the aqueous phase is extracted with DCM, the combined organic phases are washed with dilute NaCl solution (better phase separation), dried over sodium sulfate, filtered and evaporated in vacuo to give the reaction product as a foam of red coagulability (solvadifying), for further purification the product is filtered through silica gel with DCM/MTBE (9:1 to 85:15), and the product fractions were evaporated in vacuo. The reaction product obtained was a red, solidifying foam. It has the following properties.

Phase (1): tg (glass transition temperature) 52 ℃, C (melting point) 57 ℃ I, decomposition >175 ℃.

MS(APCI)＝1734。

The following compounds were prepared analogously to the one or more synthetic sequences described.

Substance/synthesis example 3:

phase (1): tg (glass transition temperature) -3 ℃ I (isotropic), decomposition >100 ℃.

Substance/synthesis example 4:

phase (1): tg (glass transition temperature) 5 ℃ I (isotropic), decomposition >180 ℃.

Substance/synthesis example 5:

phase (1): tg (glass transition temperature) 5 ℃ I (isotropic), decomposition >170 ℃.

Substance/synthesis example 6:

phase (1): tg (glass transition temperature) 27 ℃ I (Isotropic)

Substance/synthesis example 7:

substance/synthesis example 8:

phase (1): tg (glass transition temperature) -3 ℃ I (Isotropic)

Substance/synthesis example 9:

phase (1): tg 22K 112I

Substance/synthesis example 10:

phase (1): Tg-2I.

Substance/synthesis example 11:

examples of mixtures

Example 1 and corresponding comparative example

Liquid crystal mixtures having the compositions and properties shown in the following table were prepared and investigated. The improved stability of the mixtures comprising the compounds of formula I is shown by comparison with an unstabilized base mixture as reference.

The following mixture (M-1) was prepared and studied

First, the stability of the voltage holding ratio of the mixture (M-1) itself was determined. The stability of the mixture M-1 to backlight irradiation was investigated in a test cell with an alignment material for planar alignment having a layer thickness of 6.0 μ M and a flat ITO electrode. To this end, the one or more mixtures are tested for exposure to a backlight. For this reason, the stability of the respective test cell to LED (light emitting diode) backlighting for LCDs was investigated. For this purpose, the respective test cartridge is filled and sealed. The cells were then exposed to commercial LCD backlighting multiple times. No additional heat is applied other than that generated by the backlight. The "voltage holding ratio" was then determined in each case after 5 minutes at a temperature of 100 ℃. The results are summarized in the following table, table 1 a.

Here, six test cartridges were filled and studied for each individual mixture, as shown below. The indicated value is the average of six individual values.

The relative deviation of the "voltage holding ratio" values in the various measurement series is typically in the range of about 3% to 4%.

100ppm, 500ppm or 1000ppm of the reference compound R-1 are added to the other three mixtures M-1,

and correspondingly 100ppm, 500ppm or 1000ppm of compound I-2 are added to the other three mixtures M-1,

as described above, the stability of the resulting mixtures (C-1.1, C-1.2 and C-1.3 and M-1.1, M-1.2 and M-1.3) was investigated. The results are shown in the following table, tables 1a to 1 c.

In addition to the compounds of formula I, reference compound R-1 and a further reference compound R-3 have also been used herein.

TABLE 6a

Example 2 and corresponding comparative example

The following mixture (M-2) was prepared and studied.

First, the stability of the mixture (M-2) itself was determined. For this reason, the stability of the mixture M-2 to backlight irradiation was investigated in a test cell with an alignment material for planar alignment having a layer thickness of 6.0 μ M and a flat ITO electrode. To this end, the one or more mixtures are tested for exposure to a backlight. For this reason, the stability of the respective test boxes for LED (light emitting diode) backlighting for LCDs was investigated. For this purpose, the respective test cartridge is filled and sealed. These test cartridges were then exposed to commercial LCD backlighting multiple times. No additional heat is applied other than that generated by the backlight. The "voltage holding ratio" was then determined in each case after 5 minutes at a temperature of 100 ℃.

Example 3 and corresponding comparative example

The following mixture (M-3) was prepared and studied.

The stability of the mixture M-3 with respect to UV radiation is investigated with respect to its voltage holding ratio. For this purpose, the mixture is also divided into several portions.

First, the stability of the mixture (M-3) itself was determined. For this reason, the stability of the mixture M-3 to UV exposure was investigated in a test cell with a suitable polyimide as alignment material for planar alignment and a flat ITO electrode with a layer thickness of 6.0 μ M. For this, the respective test cassettes were irradiated in Suntest for 30 minutes. The voltage holding ratio was then determined in each case after 5 minutes at a temperature of 100 ℃. The addressing frequency (or measurement frequency) here is 60Hz, unless specified otherwise.

Example 4

The following mixture (M-4) was prepared and studied.

As described in examples 1 to 3, the mixture M-4 was also divided into several parts, and such studies as well as studies with various added compounds were carried out in a test cell with a planar aligned alignment material and a planar ITO electrode for its exposure stability to LCD backlight and UV source.

Example 5

The following mixture (M-5) was prepared and studied.

As described in examples 1 to 4, the mixture M-5 was also divided into several parts, and such studies as well as studies with various added compounds were performed in a test cell with a planar aligned alignment material and a planar ITO electrode for its exposure stability to LCD backlight and UV source.

Example 6

The following mixture (M-6) was prepared and studied.

As described in examples 1 to 6, the mixture M-6 was also divided into several parts, and such studies as well as studies with various added compounds were performed in a test cell with a planar aligned alignment material and a planar ITO electrode for its exposure stability to LCD backlight and UV source.

Claims

1. Liquid-crystalline medium, characterised in that it comprises

a) One or more compounds of formula I

Wherein

R¹¹Each occurrence independently of the other being H, F, orHaving 1-20C atoms, straight or branched alkyl chain, one of which is-CH₂-a group or, if present, a plurality of-CHs₂The radical-may be replaced by-O-or-C (═ O) -but no two adjacent-CH groups₂The radical being replaced by-O-, and one or, if present, more than one-CH₂The radicals-CH-OR-C.ident.C-may be replaced by-CH-OR-C.ident.C-and one OR more H atoms may be replaced by F, OR¹³,N(R¹³)(R¹⁴) Or R¹⁵Instead of this, the user can,

R¹³each occurrence independently of the others represents a straight-chain or branched alkyl or acyl radical having 1 to 10C atoms, or an aromatic hydrocarbon radical having 6 to 12C atoms or a carboxylic acid radical,

R¹⁴each occurrence independently of the others represents a straight-chain or branched alkyl or acyl radical having 1 to 10C atoms, or an aromatic hydrocarbon radical having 6 to 12C atoms or a carboxylic acid radical,

S¹¹and S¹²Each occurrence independently of the others represents from 1 to 20Alkylene of C atoms, one of which being-CH₂-a group or, if present, a plurality of-CHs₂The radicals-may be replaced by-O-or-C (═ O) -without two adjacent-CH groups₂The radical being replaced by-O-, and one OR more H atoms being able to be replaced by F, OR¹³,N(R¹³)(R¹⁴) Or R¹⁵Instead of, or in addition to, a single bond,

Y¹¹to Y¹⁴Each independently of the others represents a methyl or ethyl group,

Z¹¹to Z¹⁴Independently of one another, each occurrence represents-O-, -C-O-O-, -C-O-, -O- (C-O) -O-, -N-R¹³)-,-N-R¹³- (C ═ O) -or if S¹¹Is a single bond, but Z represents a single bond¹¹And Z¹²Both do not represent-O-simultaneously, and, however, if S is¹²Is a single bond, Z¹³And Z¹⁴Both do not simultaneously represent-O-, and if-X¹¹[-R¹¹]_o-is a single bond, Z¹²And Z¹³Does not simultaneously represent-O-,

X¹¹the expression C is shown in the specification,

p represents a number of 1 or 2,

o represents (3-p),

n p represents an integer from 3 to 10, preferably to 8,

in the case where p is 1,

n represents 3,4,5, 6 or 8, particularly preferably 4,6 or 8, very particularly preferably 4 or 6, and

m represents (10-n), and,

in the case where p is 2,

m represents (4-n), and

represents an organic group having (m + n) binding sites,

and wherein, in the case where p ═ 1, -X¹¹[-R¹¹]_o-alternatively may also represent a single bond, and

b) one or more compounds selected from the group consisting of formula II and III,

wherein

Instead of this, the user can,

represent independently of each other at each occurrence

L²¹And L²²Independently of one another, represent H or F,

X²represents halogen, haloalkyl or alkoxy having 1 to 3C atoms or haloalkenyl or alkenyloxy having 2 or 3C atoms,

m represents 0,1,2 or 3,

R³represents H, a non-fluorinated or fluorinated alkyl group or a non-fluorinated or fluorinated alkoxy group having 1 to 17 carbon atoms,or a non-fluorinated or fluorinated alkenyl group having 2 to 15C atoms, a non-fluorinated or fluorinated alkenyloxy group or a non-fluorinated or fluorinated alkoxyalkyl group, wherein one or more CH groups₂The radicals may be

Instead of this, the user can,

represent independently of each other at each occurrence

Wherein R is^LRepresents, identically or differently on each occurrence, H or an alkyl group having 1 to 6C atoms; or

L³¹And L³²Independently of one another, represent H or F,

X³represents halogen, haloalkyl or alkoxy having 1 to 3C atoms or haloalkenyl or alkenyloxy having 2 or 3C atoms, F, Cl, -OCF₃，-OCHF₂，-O-CH₂CF₃，-O-CH＝CF₂，-O-CH＝CH₂or-CF₃，

Z³represents-CH₂CH₂-，-CF₂CF₂-, -COO-, trans-CH-, trans-CF-, -CH₂O-or a single bond, and

n represents 0,1,2 or 3.

2. The medium according to claim 1, characterized in that the total concentration of the compound of the formula I in the entire medium is from 1ppm or more to 2000ppm or less.

3. A medium according to claim 1 or 2, characterized in that it comprises one or more compounds of formula II.

4. The medium according to one or more of claims 1 to 3, characterized in that it comprises one or more compounds of the formula III.

5. Medium according to one or more of claims 1 to 4, characterized in that it comprises one or more compounds selected from the group consisting of the compounds of formulae B and S

Wherein

To represent

To represent

R^B1And R^B2Independently of one another, alkyl, alkoxy, fluoroAlkyl or fluorinated alkoxy, one of which is-CH₂The radical-may be replaced by cyclopropylene, 1, 3-cyclobutylene, 1, 3-cyclopentylene, 1, 3-cyclopentenylene, alkenyl having 2 to 7 carbon atoms, alkenyloxy, alkoxyalkyl or fluorinated alkenyl, one of which is-CH₂The group-may be replaced by cyclopropylene, 1, 3-cyclobutylene, 1, 3-cyclopentylene, 1, 3-cyclopentenylene,

n represents a number of 0 or 1,

to represent

To represent

R^S1And R^S2Independently of one another, represents alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, one of which is-CH₂The radical-may be replaced by cyclopropylene, 1, 3-cyclobutylene, 1, 3-cyclopentylene, 1, 3-cyclopentenylene, alkenyl having 2 to 7 carbon atoms, alkenyloxy, alkoxyalkyl or fluorinated alkenyl, one of which is-CH₂The group-may be replaced by cyclopropylene, 1, 3-cyclobutylene, 1, 3-cyclopentylene, 1, 3-cyclopentenylene, and

n represents 0 or 1, preferably 1.

6. Medium according to one or more of claims 1 to 5, characterized in that it comprises one or more compounds selected from the group consisting of formulae IV and V

Wherein

R⁴¹And R⁴²Independently of one another, have the above meanings for R in claim 1²The meaning given is that of the compounds,

independently of each other and if

These also occur twice, independently of one another, if present each having the meanings stated in claim 1 for

One of the meanings given is as follows,

Z⁴¹and Z⁴²Independently of each other and if Z⁴¹Two occurrences, these also independently of one another represent-CH₂CH₂-, -COO-, trans-CH-, trans-CF-, -CH₂O-，-CF₂O-, -C.ident.C-or a single bond, preferably one or more thereof represents a single bond, and

p represents a number of atoms of 0,1 or 2,

R⁵¹and R⁵²Independently of one another, have the meanings given for R⁴¹And R⁴²The meaning given is that of the compounds,

to

If present, each independently of the other, have the above pairs

One of the meanings given is as follows,

Z⁵¹to Z⁵³Each independently of the other represents-CH₂-CH₂-，-CH₂-O-, -CH ═ CH-, -C ≡ C-, -COO-or a single bond, and

i and j each independently of the other represent 0 or 1.

7. The medium according to one or more of claims 1 to 6, characterized in that it additionally comprises one or more chiral compounds.

8. A compound of formula I

Wherein the parameters have the meanings given for formula I in claim 1.

9. A compound of formula I according to claim 8, wherein p represents 2.

10. Compounds of formula I according to claim 9, selected from the compounds of formulae I-1 to I-13

11. Electro-optical display or electro-optical component, characterized in that it contains a liquid-crystalline medium according to one or more of claims 1 to 7.

12. A display according to claim 11, characterized in that it is based on IPS, FFS, VA or ECB effects.

13. A display as claimed in claim 11 or 12, characterised in that it comprises an active matrix addressing device.

14. Use of compounds of the formula I according to one or more of claims 8 to 10 in liquid-crystalline media.

15. Use of a liquid-crystalline medium according to one or more of claims 1 to 7 in electro-optical displays or electro-optical components.

16. Process for the preparation of a liquid-crystalline medium according to one or more of claims 1 to 7, characterized in that one or more compounds of the formula I according to one or more of claims 1 to 10 are mixed with one or more compounds of the formula II according to claim 1 and/or one or more compounds selected from the group of compounds of the formulae III-1 to III-4 according to claim 1.

17. Method for stabilizing a liquid-crystalline medium, characterized in that one or more compounds of the formula I as given in claim 1, and optionally one or more compounds selected from the group consisting of the compounds of the formulae OH-1 to OH-6, are added to the medium

18. Process for the preparation of compounds of the formula I according to one or more of claims 8 to 10, characterized in that alcohols containing two 1-oxo-2, 2,6, 6-tetramethylpiperidin-4-yl groups are reacted with a suitable derivatized ring structure, such as dicarboxylic acid dihalides or tetracarboxylic acid tetrahalides.